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This paper examines the bio-derived stabilization of sand-only or sand-plus-silt soils using an extracted bacterial enzyme application to achieve induced calcite precipitation (ICP). As compared to conventional microbial induced calcite precipitation (MICP) methods, which use intact bacterial cells, this strategy that uses free urease catalysts to secure bacterial enzyme-induced calcite precipitation (BEICP) appears to offer an improved means of bio-stabilizing silty-sand soils as compared to that of MICP processing. Several benefits may possibly be achieved with this BEICP approach, including bio-safety, environmental, and geotechnical improvements. Notably, the BEICP bio-stabilization results presented in this paper demonstrate (i) higher rates of catalytic urease activity, (ii) a wider range of application with sand-plus-silt soil applications bearing low-plasticity properties, and (iii) the ability to retain higher levels of soil permeability after BEICP processing. Comparative BEICP versus MICP results for sand-only systems are presented, along with BEICP-based results for stabilized soil mixtures at 90:10 and 80:20 percentile sand:silt ratios. This BEICP method's ability to obtain unconfined compressive strength results in excess of 1000 kPa with sand-plus-silt soil mixtures is particularly noteworthy. Key words: shear strength, bio-stabilization, enzyme, bacteria. Cet article examine la stabilisation bioderivee des sols de sable uniquement ou de sable-plus-limon en utilisant une application enzymatique bacterienne extraite pour obtenir une precipitation induite par la calcite (PIC). Comparee aux methodes classiques de precipitation de la calcite induite par des microbes (MICP), qui utilisent des cellules bacteriennes intactes, cette strategie qui utilise des catalyseurs a l'urease libre pour obtenir une precipitation calcique bacterienne induite par des enzymes (BEICP) semble offrir un moyen ameliore de biostabiliser les sols de sable limoneux par rapport a celle du traitement MICP. Plusieurs avantages pourraient etre obtenus grace a cette approche BEICP, notamment les ameliorations en matiere de biosecurite, d'environnement et de geotechnique. Notamment, les resultats de bio stabilisation de l'IPCEB presentes dans le present document le demontrent: (i) des taux plus eleves d'activite d'urease catalytique, (ii) une plus large gamme d'applications avec des applications de sol sablo-limoneux ayant de faibles proprietes de plasticite et (iii) la capacite de conserver des niveaux plus eleves de permeabilite du sol apres le traitement par BEICP. Les resultats comparatifs du BEICP et du MICP pour les systemes utilisant uniquement du sable sont presentes, ainsi que les resultats bases sur BEICP pour les melanges de sols stabilises a des rapports sable-limon de 90 : 10 et 80 : 20 pour cent. La capacite de cette methode BEICP a obtenir des resultats de resistance a la compression non confinee superieurs a 1000 kPa avec des melanges de sol sable-plus-limon est particulierement remarquable. [Traduit par la Redaction] Mots-cles: resistance au cisaillement, biostabilisation, enzyme, bacteries., Introduction This paper's presentation of a bacterial enzyme-induced calcite precipitation (BEICP) procedure represents yet another iterative refinement of the overall concept of bio-inspired soil stabilization, which has evolved over the [...]

The introduction of uncertainty can make a significant difference in the valuation of a project. This manifests itself, inter alia, in the regulatory constraints that can affect the valuations of the firm's investment which, in turn has an adverse impact on consumers' welfare. In particular, the inability to exercise any or all of the delay, abandon, start/stop, and time-to-build options has an economic and social cost. With this view in mind, we specify and estimate a model where regulatory constraints impact on the firm's cash flow and on investment valuation with real options methods. This paper uses real options analysis to address issues of regulation that have not been previously quantified. We show that regulatory constraints on cash flow have an impact on investment valuations in the telecommunications industry. Specifically, a model is developed to estimate the cost of regulation for broadband services. We show that the cash flow constraints and the inability to delay and abandon has a significant cost. Because some costs are not recognized in a static view of the world, this failure to recognize the operation and implications of non-flexibility by regulators (which can be modeled by real options methods) will lead to a reduction in company valuations which in turn will lead to a reduction in economics welfare., INTRODUCTION As readers of this journal are aware, [(Park 1999), (Park 2000), (Nembhard 2000), (Herath 1999), and (Herath 1999),] the real option pricing approach utilizes financial option principles to value [...]

The role of real options theory in the telecommunication industry as well as other industries is discussed. Real options offer the possibility to integrate major analytical methods into a coherent framework that more closely approximates the dynamics of the firm's behaviour without heroic assumptions regarding the dynamics of the environment.

Research describes bacterial community structures of a industrial wastewater treatment facility, consisting of four thermophilically operating and three low temperature operating reactors, by denaturing gel electrophoresis combined with PCR and cloning techniques. Similar populations of bacterial species were observed under both conditions but relative species distribution was different.

Thermophilic aerobic biological wastewater treatment was investigated at 55 degrees C in continuous-flow bioreactors using a synthetic wastewater containing gelatin and (alpha)-lactose as principal organic constituents. By operating multiple continuous-flow bioreactors at different hydraulic residence times (HRTs), the maintenance constant (k(sub d)) was calculated to be 0.046 day-(super -1), a value approximately 10-fold lower than that previously reported for thermophilic processes but similar to that for mesophilic treatment. Investigation into the bacterial community structure by denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal RNA genes revealed that the dominant phylotypes in the bioreactors changed as a function of HRT. Cell reactivity, measured as the specific content of protein and RNA, declined as HRT increased. Catabolic enzyme activities specific to the principal organics in the synthetic wastewater, however, increased at higher HRTs. In conclusion, the performance of thermophilic aerobic biological wastewater treatment processes was similar to that of conventional mesophilic processes with respect to maintenance requirements (i.e., cell yields) as well as bacterial community shifts, cell reactivity, and cell activity.