Shear failure behavior of granular-continuum interfaces

Particulate-continuum interfaces (e.g. soil-concrete, soil-steel, soil-geomembranes) determine the behavior of many geotechnical structures including deep foundations, synthetic impervious liners, trenchless technologies, and an assortment of earth retaining structures. Therefore, proper understanding of the localized shearing mechanisms that govern their behavior is essential if geotechnical design is to improve. This paper presents a summary of recent research on the coupled effect of surface roughness and hardness on interface shear behavior and strength. This was accomplished through performing a series of laboratory tests on a selection of sand-continuum material interfaces and through discrete element modeling of particulate-continuum interfaces.     

Dynamically selecting protocols for socket applications

An application enablement method that enables communications applications to run on protocols for which they were not written is discussed. The focus is on a subset of networks and communications application programming interfaces. The communications interface chosen is Berkeley sockets. The network protocols used are SNA (Systems Network Architecture) and TCP/IP (Transmission Control Protocol/Internet Protocol). The running of existing socket applications over SNA networks, which requires support for transparently masking the differences between TCP/IP and SNA from the applications, is described. Protocol selection, address mapping, and connection management are also described     

Quantifying the temporal characteristics of network congestion events for multimedia services

Effective quality-of-service (QoS) metrics must relate to end-user experience. For multimedia services these metrics should focus on phenomena that are observable by the end user. Once a congestion event occurs in the network it tends to persist, resulting in long bursts of consecutive packet loss. Such an event is observable to the network customer. There is a need to increase our understanding of the temporal characteristics of congestion. It has become increasingly apparent that the temporal characteristics of congestion events have the dominant effect on user-perceived QoS. A rigorous definition of the time between congestion events is given here, as well as an associated prediction methodology. The inter-congestion event time or the rate of congestion events per unit time provides a network quality metric that is easily understandable to network users and is conveniently predicted and measured. The contribution of this paper is the definition of a metric to characterize congestion events and development of an analytic methodology to predict the expected number of congestion events per unit time. The proposed methodology is evaluated for a variety of traffic models.     

High-speed characteristics of low-optical loss oxide-apertured vertical-cavity lasers

We characterize the high-speed modulation properties of thin-oxide-apertured vertical-cavity lasers. The modulation response scales with device diameter due to the negligible optical scattering loss present in these devices. A small diameter laser of 3.1 /spl mu/m has a maximum 3-dB bandwidth of 15.2 GHz at a bias of only 2.1 mA. Modeling indicates a no-parasitic bandwidth of 18.2 GHz at this current level, with an intrinsic 3-dB bandwidth limit of 45 GHz due to gain compression. The present devices are limited by parasitic capacitance across the thin oxide layer.     

Chemosensitization of human prostate carcinoma cell lines to anti-fas-mediated cytotoxicity and apoptosis

Androgen ablation has been an effective treatment in patients with advanced prostate cancer. However, most treated patients develop hormonally resistant disease and do not respond to conventional chemotherapy. Immunotherapy against prostate cancer is an alternative approach in overcoming hormonal/drug-resistant prostate cancer. Cytotoxic immune lymphocytes kill target cells via the perforin/granzyme and the Fas-ligand (Fas-L) pathways. We hypothesize that tumor cells respond poorly to immunotherapy by developing resistance to killing by the Fas-L mechanism. This study investigated whether prostate tumor cells are sensitive to Fas-mediated killing. The human prostate carcinoma cell lines DU145, PC-3, and LnCAP were examined for their sensitivity to killing and apoptosis by the Fas-L agonist anti-Fas antibody and CTLs. All three lines moderately expressed the Fas antigen on the cell surface; however, all three lines were relatively resistant to cytotoxicity mediated by anti-Fas (CH-11) antibody. Pretreatment of DU145 and PC-3 with subtoxic concentrations of drugs followed by anti-Fas antibody resulted in synergistic cytotoxicity and apoptosis, whereas only an additive effect was obtained with LnCAP. Chemosensitization with drugs and anti-Fas was completely blocked by the addition of neutralizing anti-Fas antibody. The murine CTL hybridoma, PMMI, which kills only via the Fas-L pathway, was able to kill chemosensitized PC-3 and DU145 but not LnCAP cells. Furthermore, this cytotoxicity was blocked by anti-Fas neutralizing antibody. Chemosensitization of PC-3 and DU145 prostate tumor cells was not due to up-regulation of Fas-receptor antigen expression. Treatment of tumor cells with cisplatin did not down-regulate the antiapoptotic genes bcl-2, FAP-1, and c-myc. Further, there was no induction by cisplatin of Fas-L on the tumor cells, thus ruling out Fas/Fas-L-mediated autologous killing. These findings demonstrate that pretreatment of drug-resistant/CTL-resistant prostate DU145 and PC-3 tumor cells with subtoxic concentrations of certain chemotherapeutic drugs sensitizes the tumor cells to Fas-mediated cytotoxicity. These findings suggest that chemosensitization of tumor cells should optimize the response to immunotherapeutic interventions in the treatment of hormone-resistant/drug-resistant prostate cancer.     

CdZnSe/ZnSe strained layer superlattices disordered by germanium diffusion

We have investigated the phenomenon of layer disordering in CdZnSe/ZnSe strained layer superlattices (SLSs) by Ge diffusion and have fabricated CdZnSe/ ZnSe optical waveguides using the Ge-induced disordering. Both the as-grown sample and the sample annealed without a Ge layer showed several orders of well-resolved double crystal x-ray satellite peaks due to SLS periodic structure. However, the satellite peaks completely disappeared in the Ge-diffused sample, indicating that the SLS structure was disordered by the Ge diffusion and not caused by the annealing process. Photoluminescence (PL) measurements at 1.4K of both the as-grown and the annealed samples without Ge diffusion show intense, sharp excitonic emission around 483 nm in CdZnSe/ZnSe SLS. After Ge diffusion, the PL peaks shift to higher energy confirming the layer disordering of the SLS. The blue shift due to disordering was also observed in the PL at room temperature (RT). The optical guided mode in the SLS guiding layer confined by the disordered alloy was confirmed. Lateral optical confinement in the stripe geometry laser was also confirmed by observing the RT stimulated emission produced by optical pumping. On leave from Matsushita Electric Industrial Co., Ltd., Osaka, Japan     

The effect of scope delimiters on program comprehension

Scope delimiters, such as BEGIN-END or DO-END, are used in many programming languages, but they can lengthen and clutter a program listing. This paper provides experimental evidence that ENDIF or ENDWHILE statement terminators make for easier to comprehend programs than BEGIN-END pairs surrounding compound statements.     

Observational biases in spouse observation: Toward a cognitive/behavioral model of marriage.

Examined the relationship between couples' (insiders') and observers' (outsiders') perspectives of marital interaction by having 10 nondistressed, and 6 distressed couples and 10 objective observers (undergraduates) evaluate the positiveness of the couples' interactional behaviors. Couples completed the Marital Adjustment Test and performed 2 conflict-resolution tasks. Results reveal that spouses' ratings of their partners' behavior were not consistent with observers' ratings of the partners' behaviors but were consistent with observers' ratings of spouses' own behaviors. Further, wives' scores are isolated as indicators of dysfunctional marital systems. Implications for the behavioral model of marital therapy and the importance of considering cognitive factors that may influence spouses' evaluations of their interactions are discussed. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)