Cloning and sequence analysis of a protective M-like protein gene from Streptococcus equi subsp. zooepidemicus

Streptococcus equi subsp. zooepidemicus, a Lancefield group C streptococcus, is a frequently isolated opportunist pathogen from a variety of animal hosts, including the horse. Previous studies have indicated that equine strains carry antigens with characteristics of the antiphagocytic M proteins on the Lancefield groups A and G streptococci. We have cloned a protective M-like protein gene (SzPW60) of an equine strain of S. equi subsp. zooepidemicus W60 and determined its sequence. This gene encodes a protein with a molecular weight of 40,123 which protects mice against subsp. zooepidemicus but not subsp. equi, stimulates antibodies which opsonize subsp. zooepidemicus but not equi, and reacts with antiserum to the protein of the parent strain. The predicted amino acid structure shows significant homology with the carboxy termini of groups A and G M proteins but no other homology. The M-like protein, although showing an extensive region of alpha helix, lacks the A, B, and C repeats found in group A M proteins and has a shorter signal sequence. A proline-rich region upstream from the LPSTGE motif contains 20 repeats of the tetrapeptide PEPK. The presence of this repeat region may account for the slow migration of the M-like protein in sodium dodecyl sulfate-polyacrylamide gel electrophoresis.     

Parallel computation of time-domain integral equation analyses ofelectromagnetic scattering and RCS

Electromagnetic scattering analyses for radar cross-section (RCS) prediction present very large computational demands. Processing on parallel machines will contribute to increasing the size of problem tractable. We present a parallel implementation of the time-domain integral equation method. The issues and options in its parallelization are identified, and domain decomposition strategies to suit these are implemented. Good parallelization is exhibited, with the most costly parts of the algorithm displaying essentially linear speedup. Demonstrations using the Cray T3D are given with, for example, results on the ~12 wavelength NASA almond obtained in ~30 min per illumination angle, using 256 processors     

Modulation of cell surface components of human breast cancer cells by retinoic acid: enhanced HLA-DR expression

A finite volume method in a boundary-fitted coordinate system together with a zonal grid method is employed to compute the flow fields and shear stresses in a two-dimensional aortic bifurcation. Eddy is found distal to plaques during pulsatile flow, whereas permanent eddies are observed only during steady flow. The computed flow fields are consistent with those visualized experimentally by other authors. It is also found that although the time averaged shear rates in a pulsatile flow are similar to those of a steady flow with mean Reynolds number in most regions, they are different in recirculation zones. This result implies that care should be taken if a steady flow shear rate were to be used in modeling shear-dependent physiological processes. The non-Newtonian viscosity has only a minor effect on the flows.     

Cancer patterns in three African populations compared with the United States black population

Cancer incidence rates and patterns in three African populations in the Gambia, Mali and South Africa, have been compared with corresponding data on the Black population in Connecticut, USA. In the African populations, total rates for cancer are much lower than that of US Blacks, even allowing for under-reporting. Chief cancers are those of the oesophagus, liver and cervix. In Mali, stomach cancer is very common. As to trends, among South African Blacks, a population in transition, rates are rising, albeit slowly, of cancers of prosperity--prostate, lung, breast and colon-rectum. Salient questions are: can the number of cancers of underprivilege be lessened, and can cancers linked with rising socioeconomic states be restrained? Discussions of common risk factors, including diet, reproduction, smoking and drinking practices, indicate that for Africans as a whole, continuing poverty will prevent major changes in cancer pattern and rises in occurrence of the disease. However, should prosperity increase for Africans in big cities, rates are ultimately likely to attain those prevailing in the US Black population. Significant avoiding action seems almost impossible.     

External optical feedback effects on intensity noise ofvertical-cavity surface-emitting lasers

The authors have experimentally evaluated the effect of external optical feedback on the relative intensity noise (RIN) of a vertical-cavity surface-emitting laser (VCSEL) diode. In the absence of optical feedback, the smallest RIN is found to be -135 dB/Hz. For optical feedback levels approaching -25 dB, the RIN is degraded by about 20 dB. The authors have measured feedback-induced power penalties in a 500-Mb/s intensity-modulation/direct-detection (IM/DD) link and determined that the penalty exceeds 1 dB if the optical feedback ratio is larger than -30 dB     

Applications of list decoding to tracing traitors

We apply results from algebraic coding theory to solve problems in cryptography, by using recent results on list decoding of error-correcting codes to efficiently find traitors who collude to create pirates. We produce schemes for which the traceability (TA) traitor tracing algorithm is very fast. We compare the TA and identifiable parent property (IPP) traitor tracing algorithms, and give evidence that when using an algebraic structure, the ability to trace traitors with the IPP algorithm implies the ability to trace with the TA algorithm. We also demonstrate that list decoding techniques can be used to find all possible pirate coalitions. Finally, we raise some related open questions about linear codes, and suggest uses for other decoding techniques in the presence of additional information about traitor behavior.     

Analysis of heat and mass transfer to determine heat loss and the rate of condensation of the MVSTs off-gas ducts

Reduction of the existing nuclear waste in the Melton Valley Storage Tanks (MVSTs) at the Oak Ridge National Laboratory (ORNL) is of utmost concern to the scientists at this facility. This paper provides proof that a combination of vault heating, sparged air heating, and prevention of condensation is the best alternative to achieve this goal. Therefore, in this study a general system of mathematical equations has been developed taking into account all of the parameters affecting evaporation and condensation. This evaporation process has been analyzed by the careful modeling of a bubble chain through the extremely viscous, radioactive liquid contained in the storage tanks. This paper discusses in detail the evaporation procedure using bubble formation, air velocity, and determining the rate at which this liquid waste can be removed from the MVSTs by evaporation under different conditions of the sparging air. An additional objective is to study the heating/cooling of the condensation process of the off-gas piping inside the vault. A laboratory scale model has also been assembled for this purpose at ORNL to verify the accuracy of the mathematical modeling. A comparison of the experimental findings with the mathematical modeling shows excellent agreement.