Coupling of Fluid Flow and Deformation in Underground Formations

The extraction of fluids from deformable underground formations has resulted in surface subsidence above the formation in several field cases. This paper demonstrates the necessity of using the coupled Biot’s equations for deformation-flow problems in deformable fluid-saturated porous media, particularly for problems involving fluid extraction or injection in underground formations. It is shown that it is not possible to decouple the fluid flow and deformation fields from Biot’s theory except for idealized one-dimensional cases where the total stresses are constant and the deformation mode can be assumed. The deficiencies of the uncoupled approach are also shown via an analysis of a case involving production-induced subsidence in a hydrocarbon field. An important prediction of the coupled analysis is the increase of pore pressure above the initial value during continuous withdrawal of fluids from deformable formations.     

BCS Superfluidity in Ultracold Li-6 Gas

Recent progress toward degeneracy in ultracold Fermi gases raise hope to reach the BCS superfluuid transition in fermionic systems, the case of ⁶ Li being very favorable in view of its expected large and negative scattering length. We discuss the physical situation in the high density regime where the critical temperature is expected to be large. Indirect interaction due to the exchange of density fluctuations should play an important role. We discuss the physical points involved in our approximate calculation of the critical temperature which retains the same set of diagrams as in the paramagnon model. Near the instability threshold, the attractive interaction due to density fluctuations gives rise to a strong increase in the critical temperature, providing a clear signature of the existence of fluctuation induced interactions.     

COMPARISON OF DIFFERENT MALT ANALYSES

The results of applying three types of analytical mashing procedure—Institute of Brewing, European Brewery Convention, and Tepral systems—to the same malts are examined. Statistical correlations of the results are made. It is concluded that the main difference between the results of the Tepral method and the other two procedures is that the first gives much lower extracts when applied to malts which would be likely to be troublesome in the brewery, and is thus more discriminatory for these. The advantages of including sparging in an analytical method are pointed out.     

A life cycle approach to modeling sea lamprey population dynamics in the Lake Champlain basin to evaluate alternative control strategies

Sea lamprey (Petromyzon marinus) is a nuisance species in the Laurentian Great Lakes and Lake Champlain that has devastated native fish populations and hampered sport fisheries development. We developed a modified stage-based life history matrix for sea lamprey to analyze the effects of various management efforts to suppress sea lamprey population growth in Lake Champlain. These efforts targeted different life stages of the sea lamprey life cycle. A beta distribution was used to distribute stochastic larval populations among twenty sea lamprey-bearing tributaries and five deltas to Lake Champlain, from which sea lamprey that survive through larval metamorphosis were then pooled into a lake-wide parasitic-phase population. Parasitic-phase survival to the spawning stage was evaluated based on proximity to the natal tributary and on the size of the resident larval population in each tributary. Potential control strategies were modeled at egg to emergence, larval, and spawning stages to reduce vital rates at each stage, with the goal of suppressing parasitic-phase production. Simulations indicate that control of the larval stage was essential to achieving this goal, and with supplemental effort to reduce the vital rates at early life stages and at the spawning stage, the parasitic-phase population can be further suppressed. Sensitivity simulations indicate that the life history model was sensitive to egg deposition rate, abundance of parasitic-phase sea lamprey from unknown, uncontrolled sources, and the method in which parasitic-phase sea lamprey select tributaries for spawning. Results from this model can guide management agencies to optimize future management programs.     

The muse approach to Or-parallel prolog

Muse (Multi-sequential Prolog engines) is a simple and efficient approach to Or-parallel execution of Prolog programs. It is based on having several sequential Prolog engines, each with its local address space, and some shared memory space. It is currently implemented on a 7-processors machine with local/shared memory constructed at SICS, a 16-processors Sequent Symmetry, a 96-processors BBN Butterfly I, and a 45-processors BBN Butterfly II. The sequential SICStus Prolog system has been adapted to Or-parallel implementation. Extra overhead associated with this adaptation is very low in comparison with the other approaches. The speed-up factor is very close to the number of processors in the system for a large class of problems.The goal of this paper is to present the Muse execution model, some of its implementation issues, a variant of Prolog suitable for multiprocessor implementations, and some experimental results obtained from two different multiprocessor systems.     

Influence of H2S addition during diamond deposition on hardmetal substrates

Diamond deposition on hardmetal substrates is an industrial process to increase the wear resistance of tools during machining operations, but till now an increase in diamond layer adhesion is desirable. The main problem during diamond deposition on hardmetal substrates is the Co content in the binder phase.H₂S was used for immobilizing the cobalt on the substrate surface. The H₂S should react with the metallic Co covering its surface with CoS. Because of this the diamond nucleation occurs easier and the Co vapour pressure is also reduced. Similar mechanisms were observed using silicon and boron vapour during substrate pre-treatment.Positive effects of H₂S addition were achieved if the H₂S is added only during the diamond nucleation period. The experiments with continuous H₂S addition were not successful.For comparison diamond deposition on Murakami/Carrot pre-treated substrates were carried out.     

Hypothesis validity of clinical research.

Hypothesis validity refers to the extent to which research results reflect theoretically derived predictions about the relations between or among constructs. The role of hypotheses in theory testing is discussed. Four threats to hypothesis validity are presented: (a) inconsequential research hypotheses, (b) ambiguous research hypotheses, (c) noncongruence of research hypotheses and statistical hypotheses, and (d) diffuse statistical hypotheses and tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)