866 research outputs found

    A Smart Market Solution to a Class of Back-Haul Transportation Problems: Concept and Experimental Testbeds

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    Abstract: Back-haul problems occur in many areas of transportation. One way rental of equipment often takes it from an area of high demand to an area of low demand. Examples include container rentals, car rentals and other cases of mobile equipment. The problem is to return the equipment to the location of need. Typically this is viewed as an administrative and scheduling problem. The approach taken here is "decentralized" in which a specially designed market organizes competition and information to minimize the cost of back-hauls without the direct intervention of administrative negotiations or command-and-control types of scheduling. Laboratory experimental methods are employed to test the concept and explore its limitations

    On the Behavioral Foundations of the Law of Supply and Demand: Human Convergence and Robot Randomness

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    This research builds on the work of D.K. Gode and Shyam Sunder who demonstrated the existence of a strong relationship between market institutions and the ability of markets to seek equilibrium - even when the agents themselves have limited intelligence and behave with substantial randomness. The question posed is whether or not market institutions account for the operation of the law of supply and demand in markets population by humans and no role required of human rationality. Are institutions responsible for the operations of the law of supply and demand or are behavioral principles also at work? Experiments with humans and simulations with robots both conducted in conditions in which major institutional and structural aids to convergence were removed, produced clear answers. Human markets converge, while robot markets do not. The structural and institutional features certainly facilitated convergence under conditions of substantial irrationality, but they are not necessary for convergence in markets in which agents have the rationality of humans

    In-situ biaxial texture analysis of MgO films during growth on amorphous substrates by ion-beam-assisted deposition

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    We used a kinematical electron scattering model to develop a RHEED based method for performing quantitative analysis of mosaic polycrystalline thin film in-plane and out-of-plain grain orientation distributions. RHEED based biaxial texture measurements are compared to x-ray and transmission electron microscopy measurements to establish the validity of the RHEED analysis method. MgO was grown on amorphous Si3N4 by ion beam-assisted deposition (IBAD) using 750 eV Ar+ ions and MgO e-beam evaporation. The ion/MgO flux ratio was varied between 0.66 and 0.42. In situ RHEED analysis reveals that during nucleation the out-of-plane orientation distribution is very broad (almost random), but narrows very quickly once well-oriented grains reach a critical size. Under optimal conditions a competition between selective sputtering and surface roughening yields a minimum out-of-plane texture at about 100 angstrom, which degrades with increasing film thickness. The narrowest in- plane orientation distribution (5.4 degrees FWHM) was found to be at an ion/MgO flux ratio between 0.55 and 0.51, in good agreement with previous experiments. The systematic offsets between RHEED analysis and x-ray measurements of biaxial texture, coupled with evidence that biaxial texture improves with increasing film thickness, indicates that RHEED is a superior technique for probing surface biaxial texture

    Suppression of adaptive immunity to heterologous antigens during Plasmodium infection through hemozoin-induced failure of dendritic cell function

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    BACKGROUND: Dendritic cells (DCs) are central to the initiation and regulation of the adaptive immune response during infection. Modulation of DC function may therefore allow evasion of the immune system by pathogens. Significant depression of the host's systemic immune response to both concurrent infections and heterologous vaccines has been observed during malaria infection, but the mechanisms underlying this immune hyporesponsiveness are controversial. RESULTS: Here, we demonstrate that the blood stages of malaria infection induce a failure of DC function in vitro and in vivo, causing suboptimal activation of T cells involved in heterologous immune responses. This effect on T-cell activation can be transferred to uninfected recipients by DCs isolated from infected mice. Significantly, T cells activated by these DCs subsequently lack effector function, as demonstrated by a failure to migrate to lymphoid-organ follicles, resulting in an absence of B-cell responses to heterologous antigens. Fractionation studies show that hemozoin, rather than infected erythrocyte (red blood cell) membranes, reproduces the effect of intact infected red blood cells on DCs. Furthermore, hemozoin-containing DCs could be identified in T-cell areas of the spleen in vivo. CONCLUSION: Plasmodium infection inhibits the induction of adaptive immunity to heterologous antigens by modulating DC function, providing a potential explanation for epidemiological studies linking endemic malaria with secondary infections and reduced vaccine efficacy

    Premature ejaculation: therapist perspectives

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    Premature Ejaculation (PE) is a common sexual dysfunction affecting approximately 20-30% of men (Porst, et al., 2007). Despite important issues relating to PE definition, diagnosis, and therapy, there is a paucity of research investigating the experiences of practitioners delivering PE treatment. For the present study, interviews were conducted with eight Psychosexual Therapists and subjected to Interpretive Phenomenological Analysis. Four master themes emerged from the analysis. These were Romantic Relationships, Vulnerability, Culture, and Diagnosis and Assessment. The Romantic Relationships theme included three sub-themes: Intimacy; Involvement; and Distress. Two sub-themes formed the Vulnerability theme: Self-Esteem; and Anxiety. The Culture theme contained three sub-themes: Religion and Ethnicity; Pornography; and Masculinity. The Diagnosis and Assessment theme included two sub-themes: Referral and Definitions. Findings have important implications for the diagnosis and treatment of PE. Future research should investigate therapist perceptions further, including those factors which impact on engagement with clients and PE treatment success

    A novel cellular pathway of antigen presentation and CD4 T cell activation in vivo

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    Dendritic cell activation of CD4 T cells in the lymph node draining a site of infection or vaccination is widely considered the central event in initiating adaptive immunity. The accepted dogma is that this occurs by stimulating local activation and antigen acquisition by dendritic cells, with subsequent lymph node migration, however the generalizability of this mechanism is unclear. Here we show that in some circumstances antigen can bypass the injection site inflammatory response, draining freely and rapidly to the lymph nodes where it interacts with subcapsular sinus (SCS) macrophages resulting in their death. Debris from these dying SCS macrophages is internalized by monocytes recruited from the circulation. This coordinated response leads to antigen presentation by monocytes and interactions with naïve CD4 T cells that can drive the initiation of T cell and B cell responses. These studies demonstrate an entirely novel pathway leading to initiation of adaptive immune responses in vivo

    Market Microstructure Design and Flash Crashes: A Simulation Approach

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    We study consequences of regulatory interventions in limit order markets that aim at stabilizing the market after an occurrence of a “flash crash”. We use a simulation platform that creates random arrivals of trade orders, that allows us to analyze subtle theoretical features of liquidity and price variability under various market structures. The simulations are performed under continuous double-auction microstructure, and under alternatives, including imposing minimum resting times, shutting off trading for a period of time, and switching to call auction mechanisms. We find that the latter is the most effective in restoring the liquidity of the book and recovery of the price level. However, one has to be cautious about possible consequences of the intervention on the traders’ strategies, including an undesirable slowdown of a convergence to a new equilibrium after a change in fundamentals

    Malaria impairs T cell clustering and immune priming despite normal signal 1 from dendritic cells

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    Interactions between antigen-presenting dendritic cells (DCs) and T cells are essential for the induction of an immune response. However, during malaria infection, DC function is compromised and immune responses against parasite and heterologous antigens are reduced. Here, we demonstrate that malaria infection or the parasite pigment hemozoin inhibits T cell and DC interactions both in vitro and in vivo, while signal 1 intensity remains unaltered. This altered cellular behaviour is associated with the suppression of DC costimulatory activity and functional T cell responses, potentially explaining why immunity is reduced during malaria infection
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