An analysis of the C-PODA protocol for a satellite data communication channel

The Contention-Based Priority Oriented Demand Assignment (C-PODA) protocol is analyzed in this paper. The average waiting time of a message is derived by applying results from bulk service queueing systems. Analytical results are validated by simulation and experimentation. The fairness problem associated with the C-PODA protocol is also studied and a fairness control algorithm is proposed.     

Effluent quality variation from multicomponent substrates in the activated sludge process

The objectives of this investigation were: (1) to examine the overall substrate removal of a three component mixture by an acclimated seed using total organic carbon measurements, (2) to observe the rates of removal of each of the three components in the mixture at four different food-to-microorganism ratios (F/M), (3) to show the effects of the composition of the substrate with varying degradability on effluent quality, and (4) to observe the effects of sludge age on total substrate removal.To accomplish these objectives, sludge from a municipal sewage treatment plant was acclimated as seed in a continuous flow, completely mixed laboratory reactor. A multicomponent substrate consisting of a mixture of glucose, phenol and sulfanilic acid, was fed at different F/M ratios. The removal rate was determined as total organic carbon and specific analytical measurements for each substrate in the influent and effluent samples were also made. Various combinations of glucose, phenol and sulfanilic acid were used as a substrate in three runs. This made it possible to observe the removal rate of each substrate in the mixture as related to their individual biodegradability as well as their influent concentrations.The results showed that for the three substrates employed in this study, the overall removal rate, in terms of total organic carbon in a mixed acclimated culture, is the sum of the individual specific removal rates. The effluent quality in terms of soluble TOC was related to the F/M or to the sludge age using Eckenfelder's kinetic model.     

Subgroups among opiate addicts: A typological investigation.

Applied a multivariate correlational clustering technique to the MMPI profiles of 1,500 addicts, subdivided into 10 subsamples (5 for each sex) representing 4 different categories of admission into treatment (civilly committed, volunteers, probationers, prisoners). Within each subsample, 2 homogeneous and replicable profile types were isolated. Type I (33% of all Ss) showed elevations on Scales 2, 4, and 8, suggesting marked subjective distress, nonconformity, and disturbed thinking. The much smaller Type II (about 7% of Ss) showed a single peak on Scale 4. 60% of Ss thus were unclustered. The 2 basic types, however, were effectively discriminated on a variety of other psychometric indices and were consistent with the 2 major profile types found among alcoholics in prior research. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contact-dependent protein secretion in Porphyromonas gingivalis

Porphyromonas gingivalis can induce its uptake by host epithelial cells; however, the nature and role of the P. gingivalis molecules involved in this invasion process have yet to be determined. In this study, modulation of secreted P. gingivalis proteins following association with gingival epithelial cells was investigated. Western immunoblot analysis showed that contact with epithelial cells or epithelial cell growth media induces P. gingivalis 33277 to secrete several proteins with molecular masses between 35 and 95 kDa. Secretion of the Arg-gingipain and Lys-gingipain proteases was repressed under these conditions. The contact-induced secreted protein profile was altered in Arg-gingipain-deficient and Lys-gingipain-deficient mutants, indicating a possible role for these proteases in the secretion pathway. The P. gingivalis contact-dependent protein secretion pathway differs to some extent from type III protein secretion pathways in enteric pathogens, as a gene homologous to the invA family genes was not detected in P. gingivalis. The secreted proteins of P. gingivalis may play a role in the interactions of the organism with host cells.     

Phosphites in polyolefin process stabilization

The use of stabilizer systems containing phosphites in polyolefins is well-established in the technical and patent literature. In addition to the known effects of improved heat and color stability for polyolfins, we have recently found that phosphite-containing stabilizer systems impart a process stabilizing effect as evidenced by melt flow analysis. By monitoring the poly-olefin melt flow after multiple extrusions with increasing temperature, it was found that the combination of phenolics and phosphites has a marked influence on the control of melt flow of polyolefins and the effect appears to be synergistic in operation.     

Effect on non-linear soil-structure interaction due to base slab uplift on the seismic response of a high-temperature gas-cooled reactor (HTGR)

In high seismic regions it has often been the practice to use oversized base slabs for the major nuclear power plant structures in order to prevent, or at least minimize, the amount of dynamic base slab uplift which will result from the overturning moments developed during seismic ground motion. Two major reasons have been expressed as to why dynamic base slab uplift should be minimized: (1) As nuclear power plants are normally designed for seismic loadings based upon linear analysis, and since soil-structure interaction becomes nonlinear when only a portion of the base slab is in contact with the soil, linear elastic analysis may be unacceptable if base slab uplift occurs (as the resultant design loads may be incorrect), and (2) substantial uplift could cause excessive toe pressures in the supporting soil and significant impact forces when the slab recontacts the soil.The primary purpose of this paper is to evaluate the importance of the nonlinear soil-structure interaction effects resulting from substantial base slab uplift occurring during a seismic excitation. The structure considered for this investigation consisted of the containment building and prestressed concrete reactor vessel (PCRV) for a typical HTGR plant. A simplified dynamic mathematical model was utilized consisting of a conventional lumped mass structure with soil-structure interaction accounted for by translational and rotational springs whose properties are determined by elastic half space theory. Three different site soil conditions (a rock site, a moderately stiff soil, and a soft soil site) and two levels of horizontal ground motion (0.3 and 0.5 g earthquakes) were considered.Based upon the parametric cases analyzed in this investigation, it may be concluded that linear analysis (which ignores the nonlinear soil-structure interaction effects of base slab uplift) can be used to conservatively estimate the important behavior of the base slab even under conditions of substantial base slab uplift. For all cases investigated here, linear analysis resulted in higher base overturning moments, greater toe pressures, and greater heel uplift distances than nonlinear analyses. It may also be concluded that the nonlinear effect of uplift does not result in any significant lengthening of the fundamental period of the structure. Also, except in the short period region (period less than half of the fundamental period) only negligible differences exist between in-structure response spectra based on linear analysis and those based on nonlinear analysis.Finally, it may be concluded that for sites in which soil-structure interaction is not significant, as for the rock site, the peak structural response (shears and moments) at all locations above the base mat are not significantly influenced by the nonlinear effects of base slab uplift. However, for the two soil sites the peak shears and moments are, in a few instances, significantly different between linear and nonlinear analyses. As a result, linear analysis may be used to determine all structural response for rock sites even when there is substantial base slab uplift. However, for soil sites, nonlinear analyses are necessary if substantial base slab uplift occurs.     

A genetic approach to the interpretation and evaluation of the process-reactive distinction in schizophrenia.

The hypothesis tested was that schizophrenics manifesting the "process" syndrome show more regressive and immature thought processes than those showing the "reactive" syndrome. 24 male and 27 female hospitalized schizophrenics who were newly admitted served as Ss. Social history data were evaluated in terms of the process-reaction dimension and their psychological test results were evaluated for thought processes. Instruments used were the Elgin Prognostic Scale, Rorschach, and Benjamin Proverbs. A significant correlation was found between the Rorschach genetic level score and the Elgin Prognostic Scale for male and female Ss. Only for the male Ss was the hypothesis confirmed with the Proverbs test. 29 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Placing a 20 000-hp Motor in Service

Placing major pieces of electrical equipment in service is aided by a systematic approach to selection, specification, inspection, shipment, storage, check-out, and run-in. This paper describes the detailed planning that helped assure a successful start-up of a large electrical motor. Although a specific installation is described, it will be found that many of the procedures will be generally applicable.     

Iodine stability in iodized salt dual fortified with microencapsulated ferrous fumarate made by an extrusion-based encapsulation process

The development of a novel, extrusion-based process for making microencapsulated ferrous fumarate for salt double fortification has been reported earlier. This paper focuses on the results of a one-year storage test, specifically the stability of both iodine and ferrous iron in the double fortified salt (DFS) samples prepared using optimal formulations of the iron premix. The study was devised to test the effectiveness of the encapsulation system in the prevention of interaction between ferrous fumarate and iodine, and preservation of the iodine in iodized salt. The results confirmed that direct iodine–iron interaction occurred in the DFS samples when the iron compound was added without proper coating. However, when an appropriately encapsulated iron premix was used, the interaction could be completely prevented. The extrusion-based process has proven to be an effective approach to producing a stable, bioavailable iron premix, suitable for incorporation into iodized salt for combating iodine and iron deficiencies.