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Water SA
On-line version ISSN 1816-7950
Print version ISSN 0378-4738
Water SA vol.40 n.2 Pretoria Apr. 2014
Finite difference simulation of biological chromium (VI) reduction in aquifer media columns
Phalazane J Mtimunye; Evans MN Chirwa
Water Utilisation Division, Department of Chemical Engineering, University of Pretoria, Pretoria 0002, South Africa
A mechanistic mathematical model was developed that successfully traced the Cr(VI) concentration profiles inside porous aquifer media columns. The model was thereafter used to calculate Cr(VI) removal rate for a range of Cr(VI) loadings. Internal concentration profiles were modelled against data collected from intermediate sample ports along the length of the test columns. For the first time, the performance of a simulated barrier was evaluated internally in porous media using a finite difference approach. Parameters in the model were optimised at transient-state and under near steady-state conditions with respect to biomass and effluent Cr(VI) concentration respectively. The best fitting model from this study followed non-competitive inhibition kinetics for Cr(VI) removal with the best fitting steady-state parameters: Cr(VI) reduction rate coefficient, k = 5.2x108 l-mg"1-h"1; Cr(VI) threshold inhibition concentration, C = 50 mg-l-1; and a semi-empirical reaction order, n = 2. The model results showed that post-barrier infusion of biomass into the clean aquifer downstream of the barrier could be limited by depletion of the substrates within the barrier. The model when fully developed will be used in desktop evaluation of proposed in situ biological barrier systems before implementation in actual aquifer systems.
Keywords: in situ bioremediation, porous media reactors, Cr(VI) reduction, finite difference model
C Cr(VI) concentration (ML-3)
Cr Cr(VI) toxicity threshold coefficient (ML-3)
Fc molar flow rate of Cr(VI) (MT-1)
k reaction rate coefficient (L3M-1T-1)
Q inflow rate (L3T-1)
Δc rate of change of Cr(VI) (ML-3T-1)
W mass of the aquifer soil particles (M)
ρ density of aquifer soil particles (ML-3)
Industrial activities such as leather tanning, electroplating, wood preservation/processing, and alloy preparation have led to widespread chromium contamination of soils and ground-water resources around the world (Allen et al., 1998; Shi et al., 2009). The improper disposal of Cr(VI)-containing waste from these industries and its subsequent mobility in ground-water aquifers is a subject of paramount concern (Chirwa and Molokwane, 2011; Blowes, 2002). Aquifer systems below and around industrial and mining sites are especially vulnerable to contamination. Contamination of aquifers has resulted in elevated Cr(VI) levels, sometimes rendering the groundwater unsuitable as a potable water supply source (Egwuonwu et al., 2011; DWAF, 2005; Francisco et al., 2002).
Cr(VI) has been classified by the USEPA since 1978 as a Class A human carcinogen based on its acute toxicity at high concentration and chronic and subchronic toxicity under low exposure conditions (Federal Register, 2004). Deleterious effects resulting from exposure to Cr(VI) include skin dermatitis, irritation of the mucous membrane, and DNA damage or mutations (Cheung and Gu, 2007; Caglieri et al., 2006). Cr(VI) has also been known to hinder seed germination and cause morphological changes in plants (James et al., 1984; Towill, 1978). So far, contamination of groundwater resources around mining areas has been shown to exceed the internationally acceptable exposure limit of 0.05 mg-£-1 in a significant number of groundwater resources (Molokwane et al., 2008; Kobya, 2004; Baral and Engelken, 2002).
Reduction of Cr(VI) to C(III) is favoured since Cr(III) is 1 000 times less toxic and more stable than Cr(VI) in aquatic environments under natural conditions (pH 7, 15-25°C temperature) (Boni and Sbaffoni, 2009). Currently, Cr(VI) contamination in groundwater systems is conventionally treated using the pump-and-treat method which involves the extraction of contaminated water from the aquifer, treatment above ground, and injection of the treated water back into the aquifer (Kurniawan et al., 2006; Watts, 1998). Experience at sites where pump-and-treat remediation of Cr-contaminated groundwater is underway suggests that, although it is feasible to remove high levels of Cr from the subsurface, it becomes more difficult to remove the remaining Cr as concentration decreases (Wittbrodt and Palmer, 1992). Additionally, the method is environmental intrusive in that chemical agents used in the reduction process and hydroxide precipitates of reduced chromium produce toxic sludge that may be difficult to remediate (Gonzalez et al., 2003; Blowes, 2002).
Recent studies have shown the possibility of using locally isolated organisms to treat Cr(VI) contaminated groundwater and/or soil. The treatment can be implemented ex situ utilising a pump-and-treat approach or in situ as a permeable reactive barrier (Molokwane and Chirwa, 2009; Tseng and Bielefeldt, 2002; Turick et al., 1998). In the study by Molokwane and co-workers (2008, 2009), microorganisms isolated from dried digested sludge (from sand drying beds) successfully reduced and immobilised Cr(VI) in extracted aquifer columns in the absence of any added external carbon sources. This demonstrated that a remediation strategy could be implemented using microorganisms without the risk of contaminating the aquifers with external carbon sources and nutrients. The study also demonstrated that locally isolated microorganisms could be adapted to operate at higher Cr(VI) loading conditions thereby eliminating the need for using foreign isolates of bacteria. However, in spite of these new findings, the activity of the organisms inside the columns was not evaluated.
In this study, the model of Cr(VI) removal along the reactor columns is evaluated in detail using intermediate sampling ports installed along the reactor columns. This enabled us to plot the Cr(VI) concentration profiles along the length of the reactor at any given time. The simulation of internal concentration profiles enabled us to evaluate the fundamental physical processes within the soil columns. Without the internal analysis, only a black-box approach may be employed allowing prediction only in a narrow range of operating conditions (Zabiri and Mazuki, 2010; Gomm et al., 1996).
Culture and media
Cr(VI) reducing organisms were collected from sand drying beds of sludge digester effluent at Brits Wastewater Treatment Works (Brits, North West Province, South Africa). The wastewater treatment plant has received periodic loadings of Cr(VI)-contaminated effluent since 1996, thus some of the microorganisms in the sludge were expected to be Cr(VI) tolerant and candidates for Cr(VI) reduction. Isolates capable of reducing Cr(VI) were purified and sub-cultured under micro-aerobic conditions. All the culturable Cr(VI)-reducing species from the original sludge samples were represented as shown in Table 1.
Bacteria was sub-cultured directly from single species culture slants into sterile Luria-Bettani or nutrient broth amended with 75 mg-£-1 Cr(VI) and then incubated at 30±2°C for approximately 24 h. The overnight-grown mixed culture of bacteria was then harvested by centrifugation and washed twice with 0.85% sterile NaCl. Finally, the cells were suspended in sterilised modified basal mineral medium (BMM) prepared according to Roslev et al. (1998) and the suspension was used to inoculate the columns.
Reactor system
Aquifer columns extracted from the actual contaminated site (Brits, North West Province, South Africa) were installed in the laboratory as continuous-flow columns (Fig. 1). The extracted columns were encased in tight fitting Plexiglas cylinders (60 cm long, 5 cm internal diameter). Five equally spaced longitudinal sampling ports were drilled along each column. The columns were capped on both ends with PVC caps with a provision for influent and effluent sampling ports. Before closing the columns on both ends, one of the columns (R3) was sterilised by autoclaving for 20 min at 121°C to serve as an abiotic control. The operational conditions of the experimental columns are shown in Fig. 1.
The aquifer soil columns were then installed vertically on a mounting board. Reservoirs feeding the reactors were interconnected with an overflow to maintain a constant hydraulic head of 76 cm in all columns. The applied hydraulic head corresponded to the average summer water table above the sample collection depth at the target test site. The reactors (R2) and (R4) were each seeded with 100 m£ suspension containing 8 χ 1010 cells of mixed-culture at a very slow rate of 0.28 m£-min-1 for 48 h, enough time to allow uniform distribution and adhesion of cells to soil particles. Cr(VI) loading in the reactor columns was simulated by gravity feeding as in the case of open aquifers at the actual contaminated site. Microcosm reactors were operated as packed-bed reactors at different influent Cr(VI) concentrations (20-50 mg-£-1) corresponding to the seasonal change in concentration at the site. Samples withdrawn from the equally-spaced sampling ports and from the effluent port at the bottom were centrifuged at 6 000 r-min-1 (2 820 χ g) for 10 min to remove cells and soil particles before analysis.
Since the system is being developed for application in a nutrient-deficient groundwater environment, some reactors were operated without added organic carbon source to test performance under autotrophic conditions and some were operated with carbon sources from decaying roots and leachate from decaying vegetation on the surface. Organic sources were simulated by a layer of sawdust (2 cm) to continuously leach organics into the soil column. The leachate was characterised by GC/MS and quantified by TOC Analyser to check for biodegradable organic content from the feed stream.
Analytical methods
Sample pre-concentration and loading
Volatile organics were mobilised from soil and water samples using a Turbo Matrix 40 Headspace (Perkin-Elmer, Connecticut, USA) equipped with a trap. The organics were extracted by boiling at the headspace oven temperature of 80°C for 40 min at a vial pressure of 206.84 kPa (30 psi) and desorbed onto the GC column at 103.42 kPa (15 psi).
Characterisation of organics
Organics extracted in the headspace unit above were desorbed from the trap into the PerkinElmer GC/MS system comprising of a Clarus 600 GC, and a Clarus 600T Mass Spectrometer (MS) (Perkin Elmer, Connecticut, USA) using helium as carrier gas. The GC was equipped with a Perkin Elmer Elite - 5MS capillary column (30 m χ 0.25 mm ID χ 0.5 µηι fixed phase). Injection port temperature was set at 250°C. The column oven program was initiated at 40°C and ramped at 5°C per minute to 150°C and at 15°C per minute to 250°C with a carrier gas split flow of 3 m£-min-1 and a flow rate of 1 m£-min-1. The GC detectors were bypassed in this method. The MS method was operated using electron ionisation (EI+) mode, centroid data setting, with scan duration of 0.3 s and inter-scan delay of 0.2 s. Degradation intermediates were identified by searching for closest matches in the Wiley Mass Spectral Libraries.
Quantification of organics
The total carbon content in the organic leachate from natural organic carbon sources was analysed using the Total Organic Carbon (TOC) Analyser (Model TOC-VWP, Shimadzu Corporation, Kyoto, Japan). The TOC analyser was calibrated by dissolving different proportions of a 1 000 mg-£-1 potassium hydrogen phthalate stock solution in concentrations ranging from 0-5 mg-£-1 in a 100 m£ volumetric flask prior analysing for total carbon.
Cr(VI) and total Cr
Cr(VI) was measured using a UV/Vis spectrophotometer (WPA, Light Wave II, Labotech, South Africa) at a wavelength of 540 nm (10 mm light path) after acidification and reaction with 1,5-diphenyl carbazide to produce a purple-pink colour (APHA, 2005). Total Cr was measured at a wavelength of 359.9 nm using a Varian AA-1275 Series Atomic Adsorption Spectrophotometer (AAS) (Varian, Palo Alto, CA (USA)) equipped with a 3 mA chromium hollow cathode lamp. Cr(III) was determined as the difference between total Cr and Cr(VI) concentration.
Total and viable biomass
Total biomass was measured as a function of volatile solids (VS) in the reactor. Volatile solids were determined as the loss in dry weight of samples of the known volume after igniting the thoroughly dried sample at 600°C in furnace. A conversion factor f = 0.8 was used to convert VS to total biomass (Reynolds and Richards, 1996). Viable cells were determined using the heterotrophic (pour) plate method and colony counts as described in the Standard Methods for the Examination of Water and Wastewater (APHA, 2005), with the colonies grown on Luria-Bettani (LB) and Plate Count (PC) agar. Samples of known mass collected from the sample ports were suspended in 5 m£ sterile BMM and subjected to serial dilution. CFU counts from the top three plates were averaged and the CFU count was converted to mass concentration using a calibration conversion factor of 1.833 χ 10-10 mg-cell-1 (with R2 = 0.997).
Model development
Diffusion process
The diffusivity of Cr(VI) in water was estimated using the Nernst-Haskell equation (Longsworth, 1972):
Dc = diffusion coefficient of Cr(VI) in water (cm2-s-1)
T = absolute temperature (K)
R = universal gas constant (J-mol-1-K)
F = Faraday's constant (C-g-1-mol)
γi = ionic valence (charge) of Cr(VI) (as CrO42-)
λ = electrolytic conductance (cm2-ohm-1-C-1)
The conductance was computed from an equivalent conductance Λ = 1 000 K7C., where K = specific conductance (1 ohm-1-cm-1) estimated from tables of physical properties (Perry, 1997), and Cc = electrolyte charge concentration (equivalent charge-cm-3). A value of Dc = 1.05 χ 10-5 cm2-s-1 was found using a K value of 4.5 χ 10-6 ohm-cm-1 determined from standard 1 molar Cr(VI) solutions in water at 25oC (Garrels and Christ, 1965).
Mass transport of all dissolved species u in water follows Fick's second law of molecular diffusion:
ui = concentration of dissolved species (ML3)
Diw = diffusivity of dissolved species in water (L2Tl)
t = time (T)
z is the spatial coordinate (L) for a 1-dimensional diffusion model in the direction of z
Hydraulic characteristics
The void volume available for free flow of water in the soil column decreased as cells grew around the soil particles. This resulted in a decrease in the effective cross-sectional area [A(t)] and constrained flow with increasing time. The initial value of A(t) before biomass attachment is computed as:
V = π(ID)2. h/4, the empty-column volume (L3)
Vs = volume occupied by impermeable solids (L3)
ID = internal diameter of the reactor column (L)
h = height of the packed-bed (L)
The available cross-sectional area A(t) affects the interstitial fluid velocity u (LT1) and the stagnant liquid layer around the soil particles Lw. The thickness of the stagnant liquid layer is estimated using the Frossling's correlation (Frossling, 1938):
Diw = diffusion coefficient of dissolved species in water (L2T-1)
u = Qc/A(t), the interfacial discharge rate (LT -1)
Qc = Q in+ QR, the combined flow across the bulk liquid zone
(L3T-1), where Qin = feed flow rate (L3T-1) and QR = recycle flow rate (L3T-1)'"
dp = average particle size (L)
ν = kinematic viscosity (LT-1)
A(t) = effective cross-sectional area of the reactor (L2)
Reactor mass balance and kinetics
Removal of dissolved species over time across the bulk liquid of the soil column is represented by a set of ordinary differential equations consisting of the following aspects in its mass balance equation:
• Advection
C = effluent Cr(VI) concentration (ML-3)
V = volume of the reactor (L3)
Cin = influent Cr(VI) concentration (ML-3)
Q (Au) = influent flow rate (L3T-1)
A = cross sectional area of reactor (L2)
u = velocity of the flow (LT-1)
t = time (T)
• Reduction by microbial kinetics (reaction process)
The associated rate kinetics, which were based on non-competitively inhibited rate kinetics, were proposed by Molokwane (2010). In Molokwane's work, a finite Cr(VI) reduction capacity was assumed in immobilised cells. The acclimated cells demonstrated the capability to function normally until a toxicity threshold concentration of approximately 100 mg.ℓ-1 Cr(VI).
K = dimensionless Cr(VI) inhibition factor (MM-1)
Kc = half-velocity coefficient (ML-3)
Xa = concentration of Cr(VI) reducing cells (ML -3)
Cr= inhibition threshold concentration (ML -3)
Cin = influent Cr(VI) concentration (ML-3)
Rc = Cr(VI) reduction capacity of cells [g Cr(VI) reduced/g immobilised cells] (MM-1)
Y = cell yield coefficient (MM-1)
kms = maximum specific substrate utilisation rate coefficient (T--1)
kmc = maximum specific Cr(VI) reduction rate (T-1)
kd = cell death rate coefficient (T-1)
X = viable cell concentration (ML-3)
Due to space limitations in the reactor, cells may only grow to a certain maximum concentration [Xmax ]. The time at which the cells reach the maximum allowable concentration is dependent on initial cells, Cr(VI) toxicity and hydraulic loading rate. These conditions allow us to simplify the cell growth term (Eq. 7) to the following logistic function:
X = viable cell concentration (ML-3) at any time t (T)
Xmax = maximum attainable viable cell concentration (ML-3) in the microcosm
Xo = initial viable cell concentration (ML 3), t0 = logistic interval (T)
b = pitch (dimensionless).
• Diffusion process
Mass transfer within the attached cell layer is described by Fick's law for dispersion as presented in (Eq.(2)). The contaminant flux across the stagnant layer to the biofilm is a function of the contaminant dispersion coefficient and concentration and is represented as:
Diw = dispersion coefficient of Cr(VI) in water (L2T-l)
dC/dz = Cr(VI) concentration gradient (ML-3L-1)
LW = thickness of stagnant layer (L)
CB= bulk liquid Cr(VI) concentration (ML-3)
jC = flux of dissolved species into the biofilm (ML-2T-1)
CS = Cr(VI) surface concentration (ML-3)
NB: In most mass transfer-limited reactions CB >> Cs, therefore Cs is negligible.
• Adsorption process
kad = adsorption rate coefficient (T--1)
Ceq = equilibrium concentration at surface area (ML-3)
C = Cr(VI) concentration at any time (ML-3)
qc = rate of Cr(VI) removal by adsorption (T-1)
The adsorption and diffusion processes are facilitated by the terms (q) and (j), respectively, and the reaction process is represented by the term (r) which represents reaction by biomass (X). The term (q) can approach equilibrium easily whereas the terms (r) and (j) depend on the active biomass. The overall mass balance for dissolved species (Eqs (5) to (10)) and biomass is given by the equation below:
jc = flux of dissolved species into the biofilm (ML-2T-1)
rc = rate of removal of dissolved species by suspended cells in the bulk liquid (ML-3T-1)
λ = cell detachment rate coefficient (T-1) - a function of the interfacial velocity u (LT-1)
kd = cell death rate coefficient (T-1)
Af = available surface area (L2)
V = the bulk liquid volume (L3)
XB = biomass density in the bulk liquid (ML-3)
Xf = biomass density in the biofilm zone (ML-3)
Lf = thickness of biofilm layer (L).
Quasi-steady state kinetics
Steady-state conditions were evaluated with the soil column as a plug flow system with incremental loading per mass of reactor:
Fc = molar loading rate of Cr(VI) (MT-1)
W = mass of aquifer soil particles (M)
yc = reaction rate (ML-3T-1)
Under quasi-steady-state conditions biomass, adsorption and diffusion process in Eqs( 9) and (10) reached equilibrium. Therefore, the local reaction rate at a particular point can be simplified in terms of the Cr(VI) reduction capacity of individual cells. The reaction was originally first order but was slowed down by the toxicity of the reactant; a mixed kinetic may be represented as follows:
(Levenspiel, 1999)
C = Cr(VI) concentration along the reactor column (ML-3)
Cr = Cr(VI) toxicity threshold coefficient (ML-3)
k = reaction rate coefficient (L3M-lT-l)
n = semi-empirical dimensionless variable (MM-1)
The mass (W) and loading rate (Fc) are defined as ρAƒL and QinC, respectively, so that the differential term can be expressed in terms of dC/dL and the whole reaction term can be simplified by rearranging terms:
C = Cr(VI) concentration (ML-3) at any point (L) along the reactor column
k = reaction rate coefficient (L3M-lTl)
Qin = hydraulic loading rate (L3T1)
ρ = density of aquifer soil particles (ML-3)
Af = available surface area (L2)
L = length of the reactor (L)
The parameters ρ, Qin, and Cr are constant whereas the surface area Af varies with time as described in Eq. (3).
Assumptions governing the model in Eq.(15) are as follows:
• There is no mixing in the axial direction, this implies that molecular and/or turbulent mass dispersion is negligible in flow direction
• Uniform properties in the direction perpendicular to the flow (flow is 1-dimensional)
• The net growth of bacteria is zero near steady-state, i.e., Cr(VI) reduction is by resting cells
• The system is a homogenous catalytic system
Cr(VI) reduction kinetics in columns
Spatial and temporal variation of Cr(VI) in the columns inoculated with mixed-culture of bacteria from the dried sludge samples collected within the vicinity of the contaminated site was evaluated under both carbon source and non-carbon source conditions. Complete Cr(VI) reduction was observed in the inoculated carbon source reactor after 102 h of operation while a Cr(VI) removal efficiency of 69.5% was observed in the inoculated non-carbon source reactor at the same time of operation (Fig. 2A-B). These results suggest that the presence of the carbon source greatly enhances or stimulates the performance of Cr(VI) reduction in a biological system.
Additionally, data collected from equally-spaced longitudinal sampling ports of columns inoculated with a mixed-culture of bacteria demonstrated significant Cr(VI) reduction with maximum observable rate of approximately 2 mg-ℓ-1.h-1 between 50 and 75 h, with a removal efficiency of about 70% (Fig. 2A-B). These results demonstrate that the effluent Cr(VI) concentration in the columns inoculated with mixed-culture of bacteria did not stabilise until a quasi-steady state was achieved. The insignificant Cr(VI) reduction (< 5%) along the column at quasi-steady state, i.e. between 75 and 102 h may be associated with Cr(VI) inhibitory effects on Cr(VI)-reducing bacteria, loss of Cr(VI) reduction capacity due to blockage of pores with Cr(III) precipitate, and/or the saturation of physical chemical process-adsorption and biosorption over time.
The performance of Cr(VI) reduction between the native soil culture column amended with sawdust and the sterile-control column was also evaluated. Insignificant Cr(VI) reduction was observed in both columns with a removal efficiency of about 10% for the native soil culture column and only 2% for the sterile-control column after 102 h of operation (Fig. 3A-B). Pronounced Cr(VI) reduction observed in columns inoculated with a mixed-culture of bacteria, as compared to the native soil culture column, indicated the prominence of in situ bioremediation using target Cr(VI)-reducing species. The insignificant Cr(VI) reduction observed in the native soil culture column amended with sawdust as carbon source indicates that the native species present in the soil samples may not be Cr(VI) reducers but rather Cr(VI) resistors, as they remained persistent in the column even after long periods of exposure to Cr(VI) loadings. Additionally, insignificant Cr(VI) reduction in a sterile-control (heat-killed cells) reactor over time indicated that the abiotic processes are negligible.
Evaluation of internal processes
Parameter optimisation and model evaluation
The effluent Cr(VI) concentration across the reactor at transient-state was evaluated using the model defined in Eq. (11). The kinetic parameters were obtained by performing a nonlinear regression analysis using AQUASIM 2.0 (a computer program for identification and simulation of aquatic systems). The reliability of the model was demonstrated by near-constant optimisable parameters under different loading conditions, as shown in Table 2A. Conversely, spatial modelling of Cr(VI) concentration profile across the reactor was evaluated using the model developed under near steady-state conditions (Eq. 15).
The model was initially tested with data from the experimental run of 50 mg-£-1 Cr(VI) in the inoculated columns. The experimental run at this concentration was treated as a control due to insignificant Cr(VI) reduction (<10%) observed under these loading conditions after operation. The kinetic parameters for the model developed under near steady-state conditions were obtained using a computer program for solving numerical problems (Octave 3.0). Trial values of the optimisable kinetic parameters were initially adapted from the transient-state kinetic parameters and then adjusted as a result of low levels of biomass under near steady-state conditions. The optimum kinetic parameters (k and n) obtained from the initially tested Cr(VI) concentration under quasi-steady-state conditions were then used to simulate the experimental data under different loading conditions in both carbon source and non-carbon source columns. The model successfully captured the trends of Cr(VI) response profiles under quasi-steady-state conditions for different loading conditions. The reliability of the model was demonstrated by near-constant optimisable parameters under different loading conditions, as shown in Table 2B.
Performance evaluation under near steady-state conditions
The quasi-steady-state model was evaluated in the column inoculated with mixed-culture of bacteria under both carbon and non-carbon source conditions (Fig. 4A-C). Cr(VI) toxicity threshold; Cr in the model was assumed to be 50 mg-£-1 based on the experimental data obtained at this concentration. Fig. 4A demonstrates that the inhibitory effects of Cr(VI) removal in a non-carbon source column occurs at a faster rate than in the carbon source reactor. This indicates that the presence of organic compounds in the carbon source reactor enhances Cr(VI) reduction activity by stimulating microbial cell activity. It is also shown in Table 2A and Table 2B that minor adjustments of the kinetic parameter, k, were achieved under non-carbon source conditions as a result of slower reaction rate in the absence of carbon source. The toxicity term in the model, suggests that:
The above term implies that the greater the value of (n) in the biological system, the slower the rate at which Cr(VI) toxicity in the cells is approached. As a result of slower Cr(VI) toxic-ity rates achieved in cells at higher (n) values, the subsequent inhibitory effects of Cr(VI) reduction by Cr(VI)-reducing culture in the system are also approached at a slower rate.
Evaluation of organics in the sawdust
In order to increase the rate of Cr(VI) reduction in the inoculated column, sawdust which simulated the carbon source from decaying vegetation within the contaminated site was introduced in the column. The results from TOC analyser showed that at the initial time of incubation (tg), the total amount of organic carbon in the leachate sample was 268.7 mg-£-1and then decreased to 198.3 mg-£-1 after 12 days of incubation, suggesting that sawdust contain certain organic compounds which may be biodegradable. Additionally, GC/MS also confirmed that certain organic compounds in the sawdust leachate, such as 1-ethyl-3-vinyl, mercaptoacetic acid, Frenchol, and Bicyclo 2.2.1 heptane of molecular weight 161 g-mol-1, 73 g-mol-1, 81 g-mol-1, and 95 g-mol-1 may be partially degradable, as they were observed to be slowly disappearing in a sawdust leachate over time (Fig. 5A-B).
Microbial culture dynamics
Characterisation of initially inoculated microcosm bacteria
The mixed-culture of bacteria used for column inoculation was isolated under micro-aerobic conditions from the dried sludge. The predominant species under these conditions were the Gram-positive Bacilli. A partial sequence of 16S rRNA matched the Bacillus groups - Bacillus cereus ATCC 10987, Bacillus cereus 213 16S, Bacillus thuringiensis, Bacillus mycoides, and 2 Microbacterium groups - Microbacterium foliorum and Microbacterium sp. S15-M4.
Characterisation of microcosm bacteria after of operation
After 7 weeks of microcosm operation under oxygen-stressed conditions, a microbial community shift was expected in the non-sterile soil reactors inoculated with mixed-culture of bacteria from the dried sludge (R2 and R4), as the soil samples themselves contain a wide range of soil-dwelling species of bacteria (native soil culture). The direct measurement of viable cell concentration was challenging in the reactor since the majority of microbial species were not culturable using the conventional methods. The microbial dynamics monitored by the 16S rRNA fingerprinting method showed a decrease in culturable species. After exposure to Cr(VI) for 7 weeks the only serotypes which persisted, either through resilience against toxicity or through adaptation to changing conditions in the soil columns inoculated with mixed-culture of bacteria, were Enterobacter sp., B. cereus, and B. thuringiensis (Fig. 6). Both these Bacilli species are well known Cr(VI)-reducing species (Faisal and Hasnain, 2010; Francisco et al., 2002).
Microcosm experiments show that it is possible to introduce microbial cultures, both pure and mixed-cultures of bacteria, into the environment in a controlled manner to successfully achieve Cr(VI) reduction in flowing water. Compared to the indigenous soil culture which insignificantly removed Cr(VI) in the system, even in the presence of the added carbon source, the mixed-culture of bacteria from the dried sludge samples collected within the vicinity of a contaminated site was able to sustain high Cr(VI) removal at 40 mg.ℓ-1, which is the highest groundwater Cr(VI) concentration at the study site. Although the microbial culture showed good Cr(VI) reduction capacity, the application of a biological barrier system for in situ biore-mediation of Cr(VI) remained a challenge due to foreseeable blockage by Cr(OH)4 species in the barrier zone. The model developed in this study under quasi-steady-state conditions, which is incorporated with flow characteristics and inactivation term (C), successfully predicted the effluent Cr(VI) concentration profiles in the column inoculated with a mixed-culture of bacteria for different loading conditions, with a R2 value of 95%. Kinetic parameters obtained in the finite difference model showed highest removal rate in the column inoculated with a mixed-culture of bacteria in the presence of non-toxic carbon source, sawdust, than in the inoculated column without carbon source. These results indicate that the rate of Cr(VI) reduction in the column inoculated with target Cr(VI)-reducing species from the dried sludge samples may be limited by the substrate concentration in the system, which stimulates or encourages microbial activity. Modification of the model for application in engineering biological systems will facilitate final scale-up and operation of microbial barriers in the field.
The research was funded partially through the National Research Foundation (NRF) Incentive Funding for Rated Researchers, Grant No. IFR2010042900080 awarded to Evans MN Chirwa of the University of Pretoria.
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FEDERAL REGISTER (2004) Occupational Safety and Health Administration. Occupational Exposure to Hexavalent Chromium. 69 Federal Register 59404, 4 October 2004. [ Links ]
FRANCISCO R, ALPOIM MC and MORAIS PV (2002) Diversity of chromium-resistant and chromium-reducing bacteria in a chromium-contaminated activated sludge. J. Appl. Microbiol. 92 (5) 837-843. [ Links ]
FROSSLING N (1938) Of [Over] the volatilization of falling drops. Gerlands Beitreage Geophys. 52 170-216 (in German). [ Links ]
GARRELS RM and CHRIST CL (1965) Solutions, Minerals and Equilibria. Harper and Row Publishers, New York. 403-435. [ Links ]
GONZALEZ CF, ACKERLEY DF, PARK CH and MATIN A (2003) A soluble flavoprotein contributes to chromate reduction and tolerance by Pseudomonas putida. Acta Biotechnol. 23 (2-3) 233-239. [ Links ]
GOMM JBD and WILLIAMS JTE (1996) Development of a Neural-Network Predictive Controller. Liverpool John Moores University, Liverpool. [ Links ]
JAMES BR and BARTLETT RJ (1984) Plant-soil interaction of chromium. J. Environ. Qual. 13 (1) 67-70. [ Links ]
KOBYA M (2004) Removal of Cr(VI) from the aqueous solutions by adsorption onto hazelnut shell activated carbon: Kinetic and equilibrium studies. Bioresour. Technol. 91 (3) 317-321. [ Links ]
KURNIAWA TA, CHAN GYS, LO WH and BABEL S (2006) Physico-chemical treatment technique for wastewater laden with heavy metals. Chem. Eng. J. 118 (1-2) 83-98. [ Links ]
LEVENSPIEL O (1999) Chemical Reaction Engineering (3rd edn.). John Wiley & Sons, New York. 668 pp. [ Links ]
LONGSWORTH LG (1972) Diffusion in liquids. In: Gray DW (ed.) American Institute of Physics Handbook. McGraw-Hill Book Company, New York. [ Links ]
MOLOKWANE PE (2010) Simulation of In Situ Bioremediation of Cr(VI) in Groundwater. PhD thesis, University of Pretoria, Pretoria, South Africa. URL: http://upetd.up.ac.za/thesis/available/etd-09252010-154146/unrestricted/00front.pdf. [ Links ]
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MOLOKWANE PE, NKALAMBAYAUSI-CHIRWA EM and MELI KC (2008) Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading: Brits culture (South Africa). Water Res. 42 (17) 4538-4548. [ Links ]
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ROSLEV P, MADSEN PL, THYME JB and HENRIKSEN K (1998) Degradation of phthalate and di-(2-ethylhexyl) phthalate by indigenous and inoculated microorganisms in sludge-amended soil. Appl. Environ. Microbiol. 64 (12) 4711-4719. [ Links ]
SHI WY, SHAO HB, LI H, SHAO M and DU S (2009) Progress in the remediation of hazardous heavy metal-polluted soils by natural zeolite. J. Hazardous Mater. 170 (1) 1-6. [ Links ]
TEKERLEKOPOULOU AG, TSIAMIS G, DERMOU E, SIOZIOUS S, BOURTZIS K and VAYENAS DV (2010) The effect of carbon source on microbial community structure and Cr(VI) reduction rate. Biotechnol. Bioeng. 107 (3) 478-487. [ Links ]
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Phalazane J Mtimunye
+27 (12) 420-5894; fax: +27 (12) 362-5089
e-mail: firstname.lastname@example.com
Received 8 May 2013
Accepted in revised form 3 March 2014


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What we're about
The Indianapolis Hiking Meetup Group was formed in October 2006 by Christine B. and has grown rapidly. We're a group who enjoys the outdoors, meeting new people, and just having fun.
Our aim is to explore the great hiking spots Indiana has to offer and provide an opportunity to socialize with others who have a passion for hiking. Hikers of all levels are welcome to join. With us, you'll burn a few calories and see some great sights to boot.
I also post the events as early as I can, so that people can determine if a particular weekend will work for them.
The hikes we do are usually either moderate or rugged, depending on the park. The group is mainly for people who exercise on a regular basis or can handle the demands of the day's hike. It's important that people realize what their limits are and not attend a challenging hike they may not be ready for. Please be sure to note the hike descriptions and determine whether or not you'll be able to enjoy the event. None of us want anyone to end up injured or unable to finish a hike.
We also hike all year-round, so weather conditions can also be a factor, and although we avoid hiking in extreme temperatures (in the teens or in the nineties), please be aware of any weather conditions that may have an effect on your ability to hike.
Rugged hikes consist of lengthy events across challenging terrain, which can mean rocky streambeds and steep hills. These hikes wouldn't be recommended for beginners or those who are still getting into shape. Our rugged events are often our best hikes but are definitely a workout. Examples of these would be Clifty Falls, Turkey Run, and Shades State Parks.
Moderate hikes are not as physically challenging as the rugged ones and take place on less hilly terrain. These hikes contain a few hills that will get your heart rate up or else the length of the hike will be the real challenge. These would require a decent level of fitness and examples of moderate hikes would be Eagle Creek or Fort Harrison.
Easy hikes aren't frequently on our schedules, but that may be a matter of opinion. Any hike in this category would consist of a flat terrain and nothing strenuous.
$3 per year
The dues go toward maintaining the fee for the Meetup site and dues are paid through the site.
You are always welcome to bring a guest or guests with you, but we ask that they join if they are your guest more than a couple times. We limit the number of guests to 2 people.
We're not strictly an all-adult group, but young children may not be up for the hikes we do, so please take that into consideration. Any young people willing and able to come out are welcome.
Dogs are welcome on our hikes, as long as he or she gets along with other pooches and a large group of people. In some cases, dogs can be let off leashes while we're out on the trails, but on days when we're at a popular park, dogs will be need to be kept on leashes.
If a hike is called off due to inclement weather or some other problem, an e-mail will be sent out as early as possible letting everyone know and an update will be made to the site. Hikes are usually postponed to another weekend to avoid bad weather or any other setback.
As you can be seen from the Photos section of the site, we have some great photographers in the group and taking pictures is a big part of our events. Everyone is welcome to upload their photos to the site.
Polls are available, so feel free to post ideas.
If you have any questions at all, please feel free to contact me.
Take care,

subset: commoncrawl


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PHILADELPHIA -- The Philadelphia Eagles have signed defensive end/linebacker Chris McCoy to a three-year contract and released tackle Demetress Bell.
McCoy had five sacks in two seasons in the CFL with Calgary. McCoy was originally drafted by Miami in the seventh round in 2010. He spent his rookie season on the practice squads of the Dolphins, Seahawks and Texans. McCoy signed with Pittsburgh during the 2011 offseason, but was released before the season opener.
Bell was signed away from Buffalo last year to replace injured left tackle Jason Peters, but he lost his starting job in training camp.


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Some people are fans of the Baltimore Ravens. But many, many more people are NOT fans of the Baltimore Ravens. This 2012 Deadspin NFL team preview is for those in the latter group. Read the other Why Your Team Sucks 2012 previews here.
1. There's no white trash like Baltimore white trash. I've lived in Maryland for eight years and I can tell you that northern Maryland white trash occupies its own distinct niche of the white-trash market. It's as if the suburban Baltimore area were populated exclusively by fifth-grade gym teachers. These are the kind of people who wear camouflage Zubaz without a hint of irony. Every baby born in Baltimore County is born with a goatee, even the girls. If you could form a Jim Rome listener in a lab (and why wouldn't you? THEY'RE CLONES), the resulting 250-pound dumbfuck would look an awful lot like a white-trash Ravens fan.
These people have NO sense of humor, nor any sense of self-deprecation. That's how you end up with a fanbase that engages in a comical level of collective paranoia. Ravens fans like to pretend that they're the U. Miami of the NFL. THEY'RE OUTLAWS! EVERYBODY'S OUT TO GET THEM! The refs have it in for the Ravens. The NFL has it in for the Ravens. Dan Rooney and his owner friends have it in for the Ravens. This pre-supposes that people actually give a shit about the Ravens. They don't. The Ravens are a nothing franchise. They're the Team That Shouldn't Be. Baltimoreans have willed themselves to like this team even though they know, deep in their heart, it isn't theirs. In a perfect NFL world, the Colts are still in Baltimore, the Browns are still the Browns, and Indianapolis remains a raging tire fire in the center of flyover country. These replacement Colts will never be as lovable to the rest of the NFL as the Baltimore Colts were. They're the unwanted replacements. They're the Sammy Hagar of NFL teams. Whoa hey, did someone say Sammy Hagar? BOBBY FROM TOWSON SAYS TURN THAT SHIT UP.
2. Pussymouth isn't here to save you now. Terrell Suggs ruptured his Achilles in May, which all but ensures that the Ravens defense will be without one of its finest players for the entire season. Worst of all, that means I'm gonna have to look at sideline shots of Suggs and his terrifying gums all season long. To any network producer who plans on cutting to Suggs mid-smile, I'd like to issue a preventive PLEASE DO NOT DO THAT order. Suggs's pussymouth has been known to blind schoolchildren. I would humbly request that the Ravens not let Suggs on road trips and instead encourage him to return to his home on the set of Prometheus.
Drew Magary writes for Deadspin and Gawker. He's also a correspondent for GQ. Follow him on Twitter @drewmagary and email him at email@example.com.
3. There's no guaranteeing that John Harbaugh will know that he has a timeout left. Seriously, man. Use a fucking timeout. Get your affairs in order.
4. Ray Lewis is a phony. At some point, Ray Lewis's career will sputter to an end. More than any DPOY or MVP award, Lewis will best be remembered for his shocking ability to get the NFL establishment to turn a blind eye to the fact that he watched two friends stab people and then fled the scene in a goddamn limo. Ray Lewis is the ultimate phony, someone who will always find time to lecture teammates if there's an NFL Films camera hanging around. One day, he'll retire along with Ed Reed and this defense will finally cease to be the annual paper juggernaut it always has been. I'm quite excited for that day.
5. Hear it from Ravens fans!
Because I've convinced myself Joe Flacco is a good quarterback.
Ravens fans insist on standing to the song "Proud to be an American." I love America and all, but that song is not our National Anthem, please stop treating it as such.
Ray Rice dips his hands in butter before every carry in the playoffs, and the receivers continue to struggle catching the ball. Our defensive scheme is "let Haloti Ngata handle it," which frees up Ed Reed to wander around and double-cover the other team's third tight-end so that he can feel fast agin. Ray Lewis can cover about a yard of ground on either side and is most valuable to the team during his pre-game speeches, where he repeats his own material more than Rick Reilly.
Billy Cundiff is still on the roster. Fuck that guy. He could try and hang himself and miss kicking the stool over.
This is the Ring of Honor inside the team's stadium:
Earnest Byner
Johnny Unitas and the Baltimore Colts
Michael McCrary
Peter Boulware
Jonathan Ogden
Matt Stover
Does any team have a crappier Ring of Honor?
Also, their uniforms look like BRUISES. And they stole their logo from a security guard. Fred Bouchat had to sue. He won, and was awarded ... three dollars? I'm no economist, but I'm reasonably sure the team made more than $3 off merchandise with Bouchat's logo. Fred didn't want to sue. He took the team to court because they wouldn't honor his initial offer. He didn't care about the money, even though he was making jack squat as a security guard. He said he would be thrilled if they used his design. All he wanted in return was a helmet signed by the team. And the team said NO. So wrong on so many levels.
The reason we suck is because we cannot find a wide receiver who will not shit the bed so badly he might as well have Oregon Trail dysentery whenever a football is thrown his way in a big moment. I cannot tell you the number of times that a Ravens season has ended or been adversely affected by a DROPPED PASS. This dropped pass always occurs after we have managed to move into a tantalizingly victorious position against a good or great team. Trust me, the famous grab Torrey Smith made against the Steelers on Sunday Night Football last season was an aberration. The drops that he and Anquan Boldin both made on that very same drive-which almost KILLED the drive-show the true nature of the Baltimore Ravens.
The drops started when Flacco and Harbaugh came, since before them our "offense" was Ed Reed and Matt Stover. The first big choke-job came during a 2009 regular season game against the Patriots, whom we can never seem to beat despite always outplaying. Mark Clayton dropped a perfectly thrown pass from Flacco that would have converted a fourth down at the Patriots' 10, killing what had looked like an awesome game-winning drive and robbing us of the chance to beat the Fucktard Bradies by one point with mere seconds left in their own stadium. In 2010 we added Boldin and T.J. Houshmandzadeh to shore up the offense, but since any wide receiver who puts on a Ravens jersey is cursed to suck ass, both Boldin AND Houshmandzadeh dropped critical passes in our biggest game of the season: a playoff loss to the Steelers. In that game Boldin dropped a ball in the endzone that hit him in the numbers, and Housh dropped a fourth-down conversion.
And, of course, I am now obligated to mention Lee Evans. FUCK LEE EVANS.
Fresh off the most painful loss in franchise history, the Ravens suck because our solution to the problem was to sign Jacoby Jones this offseason. Jacoby Jones will probably now be the Ravens' #3 WR. This is the same Jacoby Jones who made millions of Texans fans facepalm themselves unconscious for five years FROM HOW MUCH HE DROPPED PASSES. It is also the same Jacoby Jones WHO MUFFED A PUNT AGAINST THE RAVENS AND HELPED THE RAVENS BEAT HIS OWN TEAM IN THE PLAYOFFS SEVEN MONTHS AGO.
I cannot tell you how un-shocked I will be when Jacoby Jones drops a pass that ends our season.
The only thrilling thing with the Ravens is to see how many times Joe Flacco can overthrow Torrey Smith before they connect on one.
Three words: Cam Fucking Cameron. This tool owes Drew Brees a lifetime of hand jobs for having a job right now. Anyone who comes from the Norv Turner coaching tree is already working on a curve, and Cam Cameron is just as bad as he is. You think Brian Billick's play calling was bad? Watch any Ravens offensive third down play and see Cam Cameron blow that shit right out of the water. 3rd and 10? Let's just run that shit up the middle. 3rd and 1? Buckle up baby, we're sending this one deep. Oh, and Billy Cundiff. Fuck Billy Cundiff.
Baltimore has the most insufferable fans on the fucking planet. Granted, losing our beloved Colts to those mouth breathing, inbred hicks in Indy sucked...but it's fucking annoying hearing a 14-year-old kid bring it up who can't spell "Atlas," let alone use one to find Indianapolis. The refs, the league, the media, the beer guy who cut you off during the second quarter because they vomited on a child...they are all out to screw the poor Ravens fan. I also love the older fans who remembers the Colts leaving, still hold a huge grudge about it, but gets annoyed about Browns fans bringing up Baltimore's actions in getting the team.
The lack of self-awareness among the fan base is fucking breathtaking. Apparently that God awful purple camo shit is considered now to be formal attire in many circles. I shit you not...I have been to weddings, funerals, and business meetings where mouth breathers have shown up in jerseys and camo pants. And the local celebrated accent isn't a fucking accent. It's a symptom of rampant inbreeding and lead poisoning. I never realized it until I did a six-year stint away from Baltimore while in the military. The average Ravens fan can't tell the difference between On Sides or vehicular manslaughter but no matter what...it's a bullshit call unless it goes the Ravens way. Watching a football with a Ravens fan is an insufferable experience. No matter what the team is doing, the fans are clamoring for them to do the opposite. Dominate running game to match the tight defense...WHY AREN'T WE THROWING IT 60 TIMES A GAME!?!
To a Ravens fan, Hines Ward and Ben Roethlisberger are/were overrated, cheap shot artists who are scum...but every single Ravens fan would gladly have them on the team in a heartbeat. Ray Lewis' involvement in the Atlanta murders...complete misunderstanding and the media targeting a big name athlete for no reason. Big Ben...SERIAL RAPIST! It is so hilarious how Steeler and Ravens fans hate each other because they are mirror images. It's like watching two retards dry hump the opposite end of a couch, shouting insults to each other.
Oh and the local hate on Flacco is insane. He is Dan fucking Marino compared to some of the clowns we have suffered through.
Wanna be part of the Deadspin NFL previews? It's simple. Just email me and give me ample evidence of why your team sucks. I'll throw any good material into the post and give you proper credit. Next team up: THE BROWNS. Oh, man. The Browns. We're gonna need a bigger Internet.


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Previous installment: Hiring Linux to Run Your Small Business
The pulling points for migrating either to the Linux desktop (to replace Microsoft Windows) or the Linux server (to replace other server environments) often are reduced to two things. One is the cost of not migrating. The other is a decision to deploy Linux gradually — or entirely — throughout the office infrastructure.
Individuals and businesses migrate to Linux for a variety of reasons. Some do it for cost efficiency. Others make the computing change for the greater flexibility open source software provides.
Either way, leaving behind an existing computing system is not impossible. Deploying Linux desktop or server takes planning and resources, but that is what any business implementation takes.
The reasons for pushing users away from Microsoft in both desktop and server deployments are different for each customer. One of the recurring migration drivers is constant threat of Microsoft license fee increases. Another is the demand for community-sponsored support in lieu of corporate proprietary solutions, according to Tomas Zubov, CEO of IceWarp.
"Stumbling blocks from Windows and Exchange involve a desire to leave Microsoft infrastructure beyond and move into a more economical system. Linux is often seen as being more stable. For instance, Linux servers have a much better uptime performance. For desktop systems as well as server systems on Linux, you do not have to do massive restarts each time an update is applied," Zubov told LinuxInsider.
Linux as an Alternative
Deploying a Linux server is usually a back-end venture that requires little or no interfacing with company workers beyond the doors of the IT office. Tackling a Linux desktop deployment is where the fear and hands-on retraining are most evident.
Making the transition to Linux is softened by the flexibility and the many desktop options Linux provides. For most computer tasks in a work environment, users are mostly concerned with the look and feel of the OS. The more it resembles Windows, the easier the transition is.
Perhaps the biggest concern for hands-on comfort with Linux at work is the software employees will use. Some people see the benefits gained by switching to Linux as being eroded by variables such as retraining staff or migration overhead to Linux from a different platform, said Shaun Sellers, senior product manager at Vision Solutions.
"Linux offers choice and freedom. While most common commercial applications are now available for Linux, there is usually an open source equivalent you can also choose from. Open source in general helps avoid vendor lock-in," Sellers told LinuxInsider.
Virtual Option
Any concerns about leaving behind a must-have software application can be removed by running the virtual machine option. Once the desired Windows business program is set up in a virtual machine window within the Linux OS, workers will not miss the Windows OS one bit.
For example, Walker White, CTO of BDNA, discovered Linux years ago, when he was planning development of an e-commerce infrastructure to support a company he started with some associates.
"I needed something that worked but was cheap to use. It got the job done. When I needed to run something in Windows, I would just spin it up in a virtual machine," White told LinuxInsider.
Know Your Options
One of the biggest concerns in retooling office computers for the Linux desktop is the software you run on them. Applying due diligence to that planning stage will ensure that no surprises happen.
"Support has been getting better on the office side of the house. There are numerous options for word processing and such — and the online migration of these software titles has helped," Mike Vitale, chief technology officer for TalkPoint, told LinuxInsider.
For example, all the software you used on Windows or the Mac you have to make sure is available on the Linux desktop, he cautioned. Are you going to be able to use Salesforce with your Linux environment? In a word, yes. Linux supports that and a whole lot more.
Look to the Clouds
What the open source distro communities might lack, cloud platform vendors can provide. One growing solution to fill in the gap of enterprise-class applications that might not be readily available on the Linux Desktop is cloud-based software.
Business products such as Intuit or any type of Software as a Service, or SaaS, products will be available as Web-based products. Some of the downloadable tools may be a bit more limited, noted Vitale.
Applications are still driving the choice of desktop, but that no longer gives Microsoft's OS a clear edge. The ability now to replace nearly every application with a Web app theoretically makes Windows or any other platform's software portable to the Linux desktop, added Rick Sizemore, director of technology transformation practice at Alsbridge.
"The big game changer today is becoming the cloud. Linux is powering most of those deployments. Even if on the user end the desktop platform is not Linux, the user will not see any difference in using the software," Sizemore told LinuxInsider.
Making the Move
Workers in many industries feel comfortable working with Windows because it is what they know. There is always a slower migration path from what you know and what is supported. That can be a barrier to entry. However, Linux communities work with enterprise clients in the SMB space.
"There is a disproportionate number of Windows users still in the workplace. Open source support is outstanding, and the communities are really robust. The crowd really does police itself," Vitale said.
As with any change, adjustments need time. Computer users need hands-on familiarity. That can happen all at once or in a trickle. That is where the planning and the staff training come into play.
"There will always be a pushback. I have people who get upset when I tell them that they won't be able to use Photoshop anymore. Instead, they have to use Gimp. People want to use what they are comfortable with," Vitale emphasized.
What It Takes
Without worries about replacing specialized software, migrating to the Linux desktop should be a no-brainer for most SMBs and bigger corporations. The Linux environment has many distros that are very similar to Windows. Some Linux distros particularly cater to the enterprise. Users have little difficulty making the switch, maintained IceWarp's Zubov.
SMB and enterprise adoption is always going to be a little bit slower, noted TalkPoint's Vitale, "but I see a lot of progress. Linux desktop options that resemble the look and feel of Windows are always an option, but it is often a better strategy to get familiar with the more standard Linux desktop interfaces."
Still, the final analysis for Linux migration has to be done on a case-by-case basis. For a larger enterprise going from a Windows environment to a Linux environment, it is a pretty big leap all at once. SMB and SOHO work places have a much less complicated process.
"You have to think about all the different software packages that have to follow along with that migration. What is your HR department using? What is your accounting department using? So many different factors are involved. So it can be difficult to switch over," said Vitale.
A lot of desktop users will focus on the little things, like how do I set my clock? Still the movement is on to get workers to use more of the newer tools. Every platform has new technology, he added.
Migration to Linux desktop will continue. There is new-found interest focusing around the bigger-known Linux options like Ubuntu, Vitale said. "More and more places are running Linux via a virtual box without removing the Windows hardware and environment."


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- Download blank character sheets (you can get pregens in from the Quick Start Adventure, below)
- Download a new saveable, fillable character sheet by Sam Carter
- Download a new form-fillable Warp Play character sheet by Chris Sellers
- Download tables and charts
- Download Stowaway to get the pregen characters.
- Download the GM Investigator Matrix.
- Download GM Troubleshooting advice.
- Download Species Cheat Sheet.
- Download quick-reference Ability Tables.
- Download a printer-friendly character sheet designed and donated by Patrick Olsson.
GM Screen
Pistacchio has designed a lovely Ashen Stars GM screen – you can download it from here:
- GM Screen (zip file)
Quick Start Adventure
Download Stowaway – the Ashen Stars 30-minute demo. Includes pregenerated characters.
If you want to introduce your players to Ashen Stars, it's much easier to get them into it if it just takes up 20 minutes of their valuable time at the beginning or end of a session. It's also a great convention demo.
Listen to Kevin Kulp run the Stowaway quick start demo for Ashen Stars:
Download here.
Thanks to the players: Tim Crosby, Chris O'Gahan, Leah Shuldiner
- Download the character creation chapter and part of the GM's Advice for Ashen Stars.
- Read an excerpt of the introduction here.


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Question and Answer Guide
LibertyBank, Eugene, OR
The FDIC has put together some responses to frequent issues or questions bank customers may have following a bank failure. These should assist you in understanding what is happening at your bank.
On Friday, July 30, 2010, LibertyBank, Eugene, OR was closed by the Oregon Division of Finance & Corporate Securities. The Federal Deposit Insurance Corporation (FDIC) was then named Receiver. Subsequent to the closure, Home Federal Bank, Nampa, ID acquired all the deposits and most of the assets of LibertyBank from the FDIC as Receiver. Share price does not trigger a bank closing and was not the reason for LibertyBank's failure. All shares of stock were owned by LibertyBank's holding company, Liberty Financial Group, Inc., which was not involved in this transaction between Home Federal Bank, Nampa, ID and the FDIC as Receiver.
YOUR MONEY IS SAFE! No one lost any money on deposit as a result of the closure of this institution.
ACCESS TO YOUR MONEY: The total balance in your account(s), including checking, savings, money market, non-brokered Certificates of Deposit, and retirement accounts, has been transferred to the new bank and will be available for transactions during regular business hours at the former bank branches. You may continue to use your outstanding checks and they will clear up to the balance in your account. Your ATM/Debit card will continue to work as usual.
DIRECT DEPOSITS: All direct deposits, for example, social security checks, payroll, veteran's benefits, welfare and/or disability, unemployment or any payment you receive electronically will continue as usual.
AUTOPAYMENTS/BILLPAY: These services will continue as usual.
INTEREST RATES: Interest on deposits accrued through close of business the day the bank was closed will be paid at your same rate. Current rates will be reviewed by the acquiring institution and may be lowered; however, you may withdraw funds from any transferred account without early withdrawal penalty until you renew your Certificate of Deposit.
BROKERED DEPOSITS: As an All-Deposits Transfer transaction, the total of all deposit accounts, including brokered deposits, have been assumed by Home Federal Bank. If you are a customer who has a Liberty Bank deposit through a broker, you must contact your broker with any questions.
SAFE DEPOSIT BOXES: You may continue to access your safe deposit box during normal business hours. Any changes will be communicated by the new bank.
OVERDRAFT LINES OF CREDIT: These lines have been transferred to the assuming bank. Please contact the new bank if you have additional questions regarding your accounts.
LOAN PAYMENTS: You should continue to make your payments according to the terms of your written contract. You may continue to make your payments at the branch office or send it to the same payment address with checks made payable to the old institution.
ESCROW PAYMENTS: All services previously performed related to your loan will continue. Should you receive notification that any portion of your taxes or insurance were not paid, notify your loan officer immediately.
LOANS IN PROCESS: Please contact your current loan officer directly.
SHARES OF STOCK: All shares of stock were owned by the holding company, Liberty Financial Group, Inc., Eugene, OR. The holding company was not included in the closing of the bank or the resulting receivership. If you are a shareholder of the holding company, please do not contact or file a claim with the receiver. You must contact the holding company directly for more information:
Liberty Financial Group, Inc.
355 Goodpasture Island Road, Suite 200
Eugene, OR 97401
CLAIMS: Please send claims for unpaid bills to the following address:
FDIC as Receiver for LibertyBank
1601 N. Bryan Street
Dallas, TX 75201
Attention: Claims Agent
DEPOSIT INSURANCE INFORMATION: If you have accounts in both the failed and the assuming institution, they will be insured separately for at least six months following the merger of the institutions. This will allow you time to restructure your accounts if necessary.
ADDITIONAL QUESTIONS: You may contact the FDIC Call Center at the number provided below with any additional questions:
FDIC Call Center
Toll free number 1-800-523-8159
Hours of Operation – Pacific Time
Friday, July 30, 2010: Until 9:00 p.m.
Saturday, July 31, 2010: 9:00 a.m. – 6:00 p.m.
Sunday, August 01, 2010: Noon – 6:00 p.m.
Thereafter: 8:00 a.m. – 8:00 p.m.
SCAMS: Be watchful for and resistant to any scams to obtain information from you by individuals or entities stating that they are acting on behalf of either the failed bank, new bank, or the FDIC. Should you be contacted by anyone requesting private information from you related to this event, please contact the call center above and you will be directed to the appropriate person.
For more information: www.fdic.gov/bank/individual/failed/libertyor.html


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Says University of Virginia social psychologist Jonathan Haidt, quoted in this John Tierney piece in the NYT, which gets pretty good if you read past the first half. The first half invites mockery for being so head-slappingly obvious. Glenn Reynolds already wrote just about exactly the post I was about to write. I might have gone even shorter, though. "Duh" is shorter than "Indeed." So, yeah, conservatives are so radically underrepresented in academia that it can't be mere chance.
But let's skip into the middle of the piece and think about the mechanisms of exclusion, these "sacred values" that displace scientific thinking. Haidt notes the example of Daniel Patrick Moynihan, back in 1965, who "warned about the rise of unmarried parenthood and welfare dependency among blacks" and "was shunned by many of his colleagues at Harvard as racist."
Similarly, Larry Summers, then president of Harvard, was ostracized in 2005 for wondering publicly whether the preponderance of male professors in some top math and science departments might be due partly to the larger variance in I.Q. scores among men (meaning there are more men at the very high and very low ends). "This was not a permissible hypothesis," Dr. Haidt said. "It blamed the victims rather than the powerful. The outrage ultimately led to his resignation. We psychologists should have been outraged by the outrage. We should have defended his right to think freely."According to Tierney, Haidt's audience of social psychologists "seemed refreshingly receptive to his argument."
A few even endorsed his call for a new affirmative-action goal: a membership that's 10 percent conservative by 2020.Affirmative action? Why not just stop giving affirmative action to liberals? I think that would get you way above the 10% quota... if you could do it. Ironically, talking "affirmative action" is inherently off-putting to conservatives. It's more of those sacred values from the tribal-moral community that ward off outsiders.
Here's Haidt on Bloggingheads, back in 2008, talking about the social psychology of conservatives and liberals. And here's Haidt's "Your Morals" website project about morality and political ideology.


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Find a Park
View Statewide Map
2 Parks Found
Manatee Springs State Park
A sparkling spring run and boardwalk beneath a cypress forest make Manatee Springs State Park a breathtaking destination for visitors to this unique Florida gem. Visitors enjoy camping, hiking, swimming and canoeing, while keeping an eye out for the West Indian manatees that frequent this park.
11650 N.W. 115 St.
Chiefland FL 32626


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Grandmom Monday: 'Breaking Dawn' Trailer Reaction!Sep 12th, 2011 | By Stefanie | Category: Fandom, Featured Articles, Videos
This week is our last "Grandmom Monday" and we're ending on a high note with my grandmother's reaction to watching the first Breaking Dawn trailer. Also in this video: watch me try to explain the concept of a teaser trailer to my grandmother. (I think this is my favorite video of the bunch.) You can also watch
[continue reading…]


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Title games feature Ravens-Pats, 49ers-Falcons
One game is a rematch. The other might feel like one - at least to one of the teams.
For the second straight year in the AFC, the New England Patriots will host the Baltimore Ravens with a trip to the Super Bowl on the line.
In the NFC, it will be San Francisco traveling to Atlanta, with the Falcons defense trying to stop a versatile, running quarterback for the second straight week.
''Russell Wilson and Colin Kaepernick are mobile quarterbacks who throw the ball at extremely accurate levels,'' Falcons safety Thomas DeCoud said. ''We can use this game as a cheat sheet to prepare for next week.''
On Sunday, the Falcons barely got past Wilson and the Seattle Seahawks, who overcame a 20-point deficit to take a one-point lead, but gave it up after Matt Ryan drove Atlanta into field goal range and Matt Bryant made a 49-yard kick with 8 seconds left.
Atlanta is the only team not making a repeat appearance in the NFL's final four. Last year, it was the Giants playing, and beating, the 49ers for the NFC title.
On Saturday, Kaepernick passed for 263 yards and rushed for 181 - a playoff record for a quarterback - to defeat Green Bay 45-31.
''We're one step closer to where we want to be,'' said Kaepernick. San Francisco hasn't been to the Super Bowl since 1995, when Steve Young led the 49ers to their fifth Lombardi Trophy.
Though the Niners must travel cross country for the game, they opened as 3-point favorites in a meeting of teams that played twice a year until 2003, when Atlanta was moved from the NFC West to the NFC South. Their only previous playoff meeting was a 20-18 win for the Falcons in the 1998 divisional playoffs. Atlanta won at Minnesota the next week to make its only Super Bowl.
San Francisco's 20-17 overtime loss last year to the Giants was part of a tense day of football that began with New England's 23-20 victory over the Ravens in the AFC title game.
In that game, Billy Cundiff missed a 32-yard field goal that would have tied the game with 11 seconds left.
This season, Justin Tucker beat out Cundiff for the kicker's job. Tucker hit a 47-yarder against Denver on Saturday to lift the Ravens to a 38-35 win in double overtime, extending Ray Lewis' career for at least one more week and putting the 17-year veteran one win away from his second Super Bowl.
''We fought hard to get back to this point and we're definitely proud of being here,'' Ravens quarterback Joe Flacco said. ''We feel like it's going to take a lot for somebody to come and kick us off that field come the AFC championship game.''
Lewis and the Ravens will have to stop the NFL's most potent offense. The Patriots put up 457 yards in a 41-28 victory over Houston, which left them one win away from their sixth Super Bowl in the 2000s.
''I think the two best teams are in the final,'' Patriots quarterback Tom Brady said. ''Baltimore certainly deserve to be here and so do we.''
The Patriots were made early 9 1/2-point favorites against the Ravens.
These teams met in the regular season and that game was also decided by a kick - Tucker's 27-yard field goal that sneaked through the right upright for a 31-30 victory. Or did it?
While the Ravens were celebrating, Pats coach Bill Belichick ran to midfield and grabbed a replacement official's arm as he tried to exit the field. The NFL fined Belichick $50,000 for the gesture.
New England is the even-money favorite in Vegas to win the Super Bowl. San Francisco is next at 2-1, followed by Atlanta (5-1) and Baltimore (8-1).
Among the possible Super Bowl story lines:
-The Harbaugh Bowl. Jim Harbaugh coaches the 49ers and John Harbaugh coaches the Ravens.
-A rematch of San Francisco's 41-34 win at New England on Dec. 16 - one of the most entertaining games of the regular season.
Online: http://pro32.ap.org/poll and http://twitter.com/AP-NFL


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This is not an offer for credit and should be used for estimation purposes only based on the information you provided. You should not base your decision on this estimate alone. Title, registration, tax and other fees, and personal circumstances such as employment status and personal credit history, were not considered in the calculations.
Diameter - 7.2 in. (183 mm)
Number - 8
Recommended - Premium unleaded
Minimum octane - 91
REV® Gen4
Bodywork - Narrow design
Manta Green
Front and center - HPG™ Plus
Rear - KYB Pro 36 Easy-Adjust
Travel - 9.2 in. (233 mm)
rMotion™ with QAS
Travel - 10.6 in. (270 mm)


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Pedestrian Safety Tips
Safety tips:
The only safe place to cross is at a designated public crossing with either a crossbuck, flashing red lights or a gate. If you cross at any other place, you are trespassing and can be ticketed or fined.
Cross tracks ONLY at designated pedestrian or roadway crossings.
Railroad tracks, trestles, yards and equipment are private property and trespassers are subject to arrest and fine. If you are in a rail yard uninvited by a railroad official you are trespassing and subject to criminal prosecution; you could be injured or killed in a busy rail yard.
It can take a mile or more to stop a train, so a locomotive engineer who suddenly sees someone on the tracks will likely be unable to stop in time.
Railroad property is private property. For your safety, it is illegal to be there unless you are at a designated public crossing.
Trains overhang the tracks by at least three feet in both directions; loose straps hanging from rail cars may extend even further. If you are in the right-of-way next to the tracks, you can be hit by the train.
Do not cross the tracks immediately after a train passes. A second train might be blocked by the first. Trains can come from either direction. Wait until you can see clearly around the first train in both directions.
Flashing red lights indicate a train is approaching from either direction. You can be fined for failure to obey these signals.
Never walk around or behind lowered gates at a crossing, and DO NOT cross the tracks until the lights have stopped flashing and it's safe to do so.
Do not hunt, fish or bungee jump from railroad trestles. There is only enough clearance on the tracks for a train to pass. Trestles are not meant to be sidewalks or pedestrian bridges!
Never walk, run, cycle or operate all terrain vehicles (ATVs) on railroad tracks, rights-of-way or through tunnels.
Do not attempt to hop aboard railroad equipment at any time. A slip of the foot can cost you a limb or your life.Be aware trains do not follow set schedules.
Any Time is Train Time!


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Tuesday, October 16, 2012
Liam and Louie
30 comments:
As Dr. Crusher said, "Brothers forgive."ReplyDelete
- AnonymousOctober 16, 2012 at 9:34 AM
What cute hams!ReplyDelete
- AnonymousOctober 16, 2012 at 9:46 AM
That louie... wish i could get to know him!ReplyDelete
- AnonymousOctober 16, 2012 at 9:51 AM
I hope these two boys go to a home together!ReplyDelete
So cute and funny! Was there a winner in that match?!ReplyDelete
OMG! Love the 5th pic down where Shrimp Louie is holding up his paw! "Help!" (As if he weren't the instigator of it all, biting Liam's ear!)ReplyDeleteReplies
- Steph H.October 16, 2012 at 11:17 AM
I thought the same thing! Although I bet he was grabbing for Laurie's face/hair/camera. I have many shots like that where a second later my hair is being pulled!Delete
My thought too!Delete
Its the "Help Me, Momma Laurie!" paw.
I really hope the Smalls go home in pairs!ReplyDelete
Ooooh parallel upside down bellies and matching paw sets. To die for.ReplyDelete
- AnonymousOctober 16, 2012 at 10:14 AM
Oh, boys, stop it! Stop being so unbelievably adorable!!ReplyDelete
- WebbthistleOctober 16, 2012 at 10:42 AM
Beautiful, beautiful, beautiful baby boys!ReplyDelete
These two little brothers are too adorable. Too cute, and too sweet. That's the way we like them too!!ReplyDelete
I just love the atmosphere in your pictures... It makes me want to crawl in there and take a nap with all those soft kitties!ReplyDelete
Eeeeee! So cute!ReplyDelete
i love the next to the last picture with both of them looking up with their paws hanging in the air. so cute, i agree with G: i want to climb in with them and nap!ReplyDelete
That's almost TOO cute for one day, Laurie! Srsly! :)ReplyDelete
- Anne BoleynOctober 16, 2012 at 12:45 PM
Back for my umpteenth look at these boys and noticed in the first picture how Louie's belly belies his puny start in life!ReplyDelete
Awwwww , they are just tooo cute <3ReplyDelete
They're so velvety and soft and sweet. I love, love, love these little boys.ReplyDelete
Is Louie ever NOT sweet and adorable? And is Liam ever NOT silly and precious? What a pair!ReplyDelete
Och! Louie's round tubby kitten belly in the first pic!ReplyDelete
And Liam looks like he's made of velvet.
So pretty babies!ReplyDelete
Oh how cute! I love the one where he's reaching out his paw, looks like he's saying "Save me from this guy!" Or maybe "Take my hand if you want to live!" hee heeReplyDelete
Oh me oh my - the cuteness, the little faces, the bellies, the outstretched paw, the pink ears, noses - them Smalls are not short on Cute!ReplyDelete
Please tell us that these two will only be adopted together...ReplyDelete
I hope these guys get adopted together. That would be adorable.ReplyDelete


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Each year I offer a public lecture at Ashland Theological Seminary. This year I chose to present on the book of Revelation. Below is the video of that lecture.
Just by way of orientation, a majority of the audience is made up of people from the community, so this is not a "scholarly presentation." Rather, it is an attempt to put good biblical scholarship in the hands of people who are in the church.
Give the audio a chance. It's a bit muffled for the first few minutes, but clears up before I begin speaking.


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The Indian Hill Big Band, led by trumpeter, composer and educator Jerry Sabatini, will present a free jazz concert Friday, March 28 at Mount Wachusett Community College, 444 Green Street. The performance will begin at 8 p.m. in the theatre of the Raymond M. LaFontaine Fine Arts Center.
Founded in 1998 and based in Littleton, the Indian Hill Big Band performs America's greatest music at venues throughout Greater Boston and beyond. Several of the members are active professional musicians from the local area who perform regularly with orchestras, chorales, musical theater organizations, ethnic music ensembles and other jazz groups.
Sabatini is recognized in the Boston jazz scene as an adventurous, creative and diverse trumpet player, improviser, composer and educator. Known for his wide range of musical taste, he performs in projects ranging from traditional jazz and Balkan brass bands to the music of the Middle and Far East and the avant guard. As an instructor, he directs jazz ensembles at Indian Hill Music School, Joy of Music Program in Worcester, and Cushing Academy in Ashburnham, where he also teaches jazz history.
The concert will serve as a live training event for MWCC's media students, who are also involved with promotion and event management.
Audio Engineering students will record sound that night with nearly 40 microphones and later mix the raw recording in the college's audio production studios. The audio mix will be synchronized to a multi-camera video recording of the event produced by MWCC's Video/Film students, who will record the concert with six synchronized cameras.
Photography students will take photos at the event for imagery needed by Graphic Design students who will create DVD package designs. The end result will be a full concert DVD and cable television program.
"As the music and performing arts program continues to grow at Mount Wachusett, I met with Susan Randazzo, Executive Director at IHMS, to explore prospects for partnership between our two schools, said Dr. Stephen Grieco, Dean of MWCC's School of Liberal Arts, Education, Humanities and Communications. "This concert not only creates a collaborative partnership but allows for a unique learning experience for our students. As dean, I am excited to extend this opportunity to our community and am looking forward to this concert production led by Jerry Sabatini, his talented musicians, and our dedicated MWCC Media Arts & Technology faculty and students."
During this public event, concert attendees agree to be recorded in the audience in photos, video and/or audio for DVD, Internet, television and other promotional materials. Seating will be available on a first-come, first served basis. Doors will open at 7:30 p.m.
The Indian Hill Big Band is an ensemble at the Indian Hill Music School, which offers private lessons and group experiences for all ages, styles, and levels. For more information, call 978-486-9524 or visit www.indianhillmusic.org.
Mount Wachusett Community College's Broadcasting and Electronic Media program prepares students for careers in television, radio, cable TV, sound recording, photography and related electronic media programs. For more information, contact MWCC at 978-630-9110 or firstname.lastname@example.com, or visit https://mwcc.edu.


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This entry was posted in Blog, Other Whisky News, Spirit of Speyside Whisky Festival and tagged bacon, BenRiach, dram18, Glen Moray, Glenrothes, Macallan on .
Spirit of Speyside Whisky Festival 2018 Wrap-up #2
Over a dozen festivals or more we at The Whisky Shop Dufftown, courtesy of our guests at Spirit of Speyside Whisky festival, have been trying to answer this question which is one of the greatest of all questions. Each year we pitch 3 new contenders against the reigning champion from the previous festival to see which one wins and goes forward to the next contest.
The winner is decided upon by guests attending our bacon roll and whisky tasting who vote for their favourite in a blind tasting. This is unsmoked bacon and no sauce. This is science!
We have collated the votes from all of the tastings we held. Counted them. Checked them again. And ensured there was no outside influence.
We can now formally announce the results:
Joint 3rd - Macallan 12 Years Old Fine Oak (1) & Glen Moray 15 Years Old (4)
Joint 1st - Benriach 10 Years Old Classic (2) & Glenrothes Vintage Reserve (3)
- The number in brackets denotes the place of the whisky in the order of the tasting.
There was just 3 votes separating the 4 whiskies involved! We will take that to mean we are getting better and better at choosing whiskies for the pairing.
As Glenrothes Vintage Reserve has been discontinued we are declaring the overall winner which will go forward to the next challenge to be Benriach 10 Years Old Classic.
Glenrothes Vintage Reserve and Glen Moray 15 Years Old were the joint winners from the last festival.
98 people took part this year and we thank them for their kind support.


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One of the curious constructions of the Internet is the term identity provider. You don't need anyone to provide you with an identity, of course. You have an innate one by virtue of being human. Rather, so-called identity providers, or IDPs, provide you with an identifier, a means of recording attributes important to that provider, and some method of proving it's you – usually a password.
This is not surprising since online identity has traditionally been viewed through the lens of an organization and its needs, not the individual and his or her needs. Identity systems are created to administer identifiers and attributes within a specific domain. The result: people end up with hundreds of online personas at hundreds of organizations. Each of these administrative identity systems is proprietary and owned by the organization that provides it; you really don't have an online identity that's independent of these many systems. Got a new address, or an updated credit card number? You'll have to deal with each of these systems one at a time in whatever manner they require.
But what if you could do that in one place at one time? Sure, Computerworld, Amazon, or whomever would still want to keep an account, and still need your updated address. But that account would be linked to an identity you provide. More importantly, it would be one you control.
Self-sovereign identiy explained
This concept is called self-sovereign identity. Self-sovereign identity starts with the notion that we all are the makers of our own identity, online and off. Because they do not rely on any centralized authority, self-sovereign identity systems are decentralized, mirroring the way identity works in real life.
Offline, our interactions flexibly support the use of attributes and credentials from numerous third parties, all presented by the very person they're about, typically by taking those credentials out of a wallet or purse and presenting them to someone else to verify. For example, take a driver's license. States issue it as a credential that you're authorized to drive. But, it's useful for a lot more. When you show up at a bar and the bartender wants proof you're over 21, you show them your driver's license.
Think about this for a minute and you'll realized that this is a minor miracle, at least compared to how online identity works. The bar has no legal contract, business relationship, or technical integration with the Department of Motor Vehicles (DMV). They didn't get anyone's permission. They just started asking people for their license. The person they're trying to verify gives them the credential. This works because the bar trusts the DMV to know your birthday. And the important information is packaged in a way that makes it easy to authenticate and difficult to forge.
The offline world makes use of decentralized credentials that are granted to and conveyed by the person they're about. Identirati call these kind of third-party credentials claims – claims that can be verified as authentic even when they're conveyed by the subject of the claim. These "verifiable claims" are the heart of self-sovereign identity.
Self-sovereignty doesn't mean that you're in complete control. But, it does define the borders within which you make decisions and outside of which you negotiate with others as peers. To continue the bar example, you get to decide what credential to present. The bar gets to decide what credentials it'll accept. It doesn't have to accept your driver's license. If the bartender thinks it's fake, he'll reject it along with you.
The problem with online identities
Self-sovereign identity works great in real life, where we carry paper or plastic credentials with us; it's been much harder to duplicate online. Online identity has suffered from five very real problems:
- The proximity problem: when you're dealing with people at a distance, opportunities for fraud abound.
- The scale problem: online identity systems are based on business relationships and technical integrations to root trust authorities. All this is expensive and only done for high-value use cases.
- The flexibility problem: current identity systems are rigid, with fixed schema and use cases.
- The privacy problem: shared identifiers, like browser cookies, allow personal information to be accumulated and correlated behind our backs. Ongoing hacks convincingly show that big centralized stores of personal information are not safe.
- The consent problem: identity systems rely on universal identifiers like email addresses, phone numbers and even Social Security Numbers that make it easy for third parties to correlate behavior and keep tabs on people without their permission.
Self-sovereign identity systems solve these problems using decentralization and cryptography. Decentralized identity has been difficult because one of the core requirements of functional identity is discovery: if you give me an identifier, I need to look it up. In the past, this has always led to centralized directories, which led to centralized identity systems.
But blockchain has changed all that.
How blockchain can solve the identity dilemma
Self-sovereign identity systems use blockchains – distributed ledgers – so that decentralized identifiers can be looked up without involving a central directory. Blockchains don't solve the identity problem by themselves, but they do provide a missing link that allows things we've known about cryptography for decades to suddenly be used. That allows people to prove things about themselves using decentralized, verifiable credentials just as they do offline.
To see how this works, consider our example of presenting your driver's license to the bar. The DMV is the claim issuer and gives you, the claim holder, a digital representation of your driver's license. The DMV uses keys linked to their decentralized identifier on the blockchain to sign the claim so that it is tamper-evident and anyone who gets it can validate that it was issued by the DMV. You have a wallet to hold your claims and can use keys linked to a decentralized identifier that you control on the blockchain to countersign the digital driver's license. When the bar needs to see that you're of legal age, you can present the digital driver's license and the bar can verify that it hasn't been changed, that the DMV issued it to you, and you're the one presenting it. Everyone can use the blockchain to lookup decentralized identifiers and retrieve any associated public keys.
Of course, any organization or person can issue whatever claims they want; you're free to store whatever claims you like in your wallet; and claim verifiers are able to choose what claims they trust. Decentralizing these choices ensures the flexibility necessary so that self-sovereign identity systems can be used for almost any purpose.
To be self-sovereign, an identity system must have certain key features:
- Persistent: An identity that can be taken away isn't self-sovereign. Identifiers in a self-sovereign identity system are long-lived, non-reusable and owned by the person who creates them. People aren't the only ones who need self-sovereign identities. Organizations and connected things also need them, and can use the same infrastructure as individuals.
- Peer-based: Sovereignty defines a border within which people have control and outside of which they interact with others as peers. People are in control of the relationships they form and the information they share, but others get to make the same choices. Self-sovereign identity systems aren't client-server, but rather peer-to-peer.
- Privacy protecting: Self-sovereignty puts the person in control of how information is shared. Consequently, any identity system that doesn't prevent correlation, minimize attribute disclosure, and provide for explicit consent puts people's information at risk and removes it from their control.
- Portable: Self-sovereignty implies choice and control. Vendor lock-in destroys both. Identifiers and associated credentials must be portable and self-sovereign identity systems must be interoperable to protect choice and control.
Several self-sovereign identity systems exist now in various stages of development, including Sovrin, uPort and Veres One. Each of these supports decentralized, self-sovereign identity but differ in how claims are issued and presented.
Self-sovereign identity is a relatively new concept and is undergoing rapid changes. Standards for decentralized identifiers and verifiable claims are being developed to provide interoperability. Ultimately, these systems should promote human dignity and protect the basic human desire for self-determination. As Joe Andrieu writes: "When we build interconnected systems without a core understanding of identity, we risk inadvertently compromising human dignity. We risk accidentally building systems that deny self-expression, place individuals in harm's way, and unintentionally oppress those most in need of self-determination."
Implemented correctly, self-sovereign identity systems provide scalable, flexible, private interactions with consent despite the issues that distance introduces. More importantly, they support natural human activities without threatening the privacy or liberty of people who use them. This is a development we can all support.


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If you're going to sacrifice your body to run 26.2 miles all at once, shouldn't you at least run them as best you can? Eric Allen (USC) and Patricia Dechow (Berkeley) took a look at finishing times for 300,000 Chicago Marathon runners from 2003 to 2011, concluding, in the style of all behavioral economics papers, that marathons are just another thing that human beings don't do optimally.
If everyone tried to run his or her best race, the researchers argue, you'd expect to see a relatively smooth distribution of finish times across the large population of marathon runners. As you can see in the chart above—which shows finish time by minute—this is not the case. Instead of running their best race, marathoners seem to care more about hitting key round number targets.
The real fun comes in the gender breakdown though. Below are charts showing finish times (now in five-minute increments) for men and women, statistically significant "bunching" times are shown in black.
The women aren't immune to bunching (there's clearly an impetus to finish in under five hours), but they can't touch the spikes that male finishers have around 3:30, 4:00, and 4:30. You can almost picture the thousands and thousands of sweaty, semi-fit dudes fighting their way across the finish line at 3:59, and then refusing to talk about anything else for the next year.


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We can all use a few tips when it comes to planning vacations at Disney. And of course, we think the food is just about the most important part of the trip!
Budgeting for all of the special meals that you'd like to enjoy is a big concern. And it may seem impossible to cut corners and save a little here and there while still enjoying yourself. But with a little creative planning, you can find some wonderful meals at some of the coolest places, all for less than you might think.
Previously, we shared our Top Picks at Walt Disney World for Meals Under $20. Today, we're back to celebrate some fantastic meals that you can enjoy at Disneyland for around $20 or less. This is by no means exhaustive — there are lots more where these came from. But for now, come with us and check out some of the great options we have to share! [Read more…]