370 research outputs found
Fraction auctions: the tradeoff between effciency and running time
Get PDFThis paper studies the sales of a single indivisible object where bidders have continuous valuations. In Grigorieva et al. [13] it was shown that, in this setting, query auctions necessarily allocate inefficiently in equilibrium. In this paper we propose a new sequential auction, called the c-fraction auction. We show c-fraction auctions guarantee approximate efficiency at any desired level of accuracy, independent of the number of bidders. We discuss the running time and the efficiency in the ex-post equilibrium of the auction. We show that by changing the parameter c of the auction we can trade off efficiency against running time.operations research and management science;
Bidding behavior in the bisection auction – an experimental investigation
Get PDFWe present a laboratory experiment in which we investigate bidding behavior with independent private values in the recently proposed bisection auction, and compare it with two classical auction formats - the Vickrey auction and the English auction. We test whether subjects behave strategically equivalent, following the dominant truth-telling strategy, as predicted by theory. Furthermore, we provide some insights concerning the learning process, the efficiency of allocation, and the revenue to the auctioneer. Data show that the bisection auction performs better than the Vickrey auction and only in some terms worse than the English auction.Economics ;
Using data mining techniques to identify “the best” operational patterns for enrollment modeling
No full textFor any Educational Institution it is very important to know the number of new students and the number of returning students. Based on these numbers, there could be conducted predictions of the budget that the institution will have for the next year.
This research will utilize pre-existing historical data from Texas Woman's University containing readily available and easily measured factors, which most institutions of higher learning will have available, and will split the existing data in all the sub sets possible. Running a chi square analysis on each set obtained, the program will be able to show us which splitting way is better for obtaining the most consistent patterns, using the provided data. The results will be compared with the results obtained running a linear regression analysis on the same data sets.
The study will introduce an extraneous hidden-time variable related to partitioning ways possible.
The program can be used in the future on any University data sets, providing the most holding combination of variables that will hold over the years
Self-perceived health in Belarus: Evidence from the income and expenditures of households survey
Get PDFBased on data from five cross-sectional household surveys conducted during 1996-2007, this study provides initial results of an analysis of self-perceived health in Belarus. The findings suggest that there has been a compression of morbidity. Self-perceived health has been improving steadily for both sexes and at all ages. Despite this notable improvement, Belarus still remains far behind Western Europe in terms of healthy life expectancy. This disadvantage is mainly due to higher mortality among the working-age population, but health at older ages also plays an important role. Education appears to be the most important factor associated with self-rated health.Belarus, healthy life expectancy, self-perceived health
Inefficiency of equilibria in query auctions with continuous valuations
Get PDFQuery auctions are iterative auctions in which bidders have to select in each round an action from a finite set. We show that, when bidders have continuous valuations, any ex post equilibrium in an ex post individually rational query auction can only be ex post efficient when the running time of the auction is infinite for almost all realizations of valuations of thebidders. Thus, when valuations are drawn from a continuous probability distribution, efficiency can only be bought at the expense of a running time that is infinite with probability one. For two bidders we even show this to be true when we only require efficiency with probability one.mathematical economics;
Resonant Terahertz Detection Using Graphene Plasmons
Get PDFPlasmons, collective oscillations of electron systems, can efficiently couple light and electric current, and thus can be used to create sub-wavelength photodetectors, radiation mixers, and on-chip spectrometers. Despite considerable effort, it has proven challenging to implement plasmonic devices operating at terahertz frequencies. The material capable to meet this challenge is graphene as it supports long-lived electrically tunable plasmons. Here we demonstrate plasmon-assisted resonant detection of terahertz radiation by antenna-coupled graphene transistors that act as both plasmonic Fabry-Perot cavities and rectifying elements. By varying the plasmon velocity using gate voltage, we tune our detectors between multiple resonant modes and exploit this functionality to measure plasmon wavelength and lifetime in bilayer graphene as well as to probe collective modes in its moiré minibands. Our devices offer a convenient tool for further plasmonic research that is often exceedingly difficult under non-ambient conditions (e.g. cryogenic temperatures) and promise a viable route for various photonic applications
Macrophage activation syndrome in COVID-19
Get PDFThe novel coronavirus epidemic is characterized by high rates of morbidity and relatively high mortality. Laboratory test results in patients include leukopenia, an increase in liver function tests and ferritin levels reaching hundreds, and sometimes thousands of units. These data remind us about the macrophage activation syndrome (MAC). Secondary hemophagocytic lymphohistiocytosis syndrome, MAC, which pathogenesis is based on a defect in the mechanisms of T-cell cytotoxicity and decreased level of natural killer cells associated with the defect in the perforin-encoding gene as well as hyperproduction of a number of cytokines – interleukin (IL)-1â, tumor necrosis factor-á, etc. by T-lymphocytes and histiocytes, indirectly leading to the activation of macrophages and production of proinflammatory cytokines, in particular IL-6 hyperproduction. MAC is one of "hyperferritinemic syndromes". These disorders have similar clinical and laboratory manifestations, and they also respond to similar treatments, suggesting that hyperferritinemia may be involved in the overall pathogenesis and is characterized by elevated ferritin level and cytokine storm. Despite the fact that data on the immune and inflammatory status in patients with COVID-19 have only started to appear, it is already clear that hyperinflammation and coagulopathy affect the disease severity and increase the risk of death in patients infected with SARS-CoV-2. Hence, understanding the pathogenesis of the novel coronavirus infection can help in its early diagnostics and treatment
Na-based crystal scintillators for next-generation rare event searches
No full textThe growing interest in clarifying the controversial situation in the Dark Matter sector has driven the experimental efforts towards new ways to investigate the long-standing DAMA/LIBRA result. Among them, low-temperature calorimeters based on Na-containing scintillating crystals offer the possibility to clarify the nature of the measured signal via particle identification. Here we report the first preliminary measurement of Na-containing crystals, based on a material different from NaI, i.e. Na2Mo2O7 and Na2W2O7, pointing out their performance in terms of energy resolution, light yield, and particle identification
Inefficiency of equilibria in query auctions with continuous valuations
Get PDFWe show that, when bidders have continuous valuations, any ex post equilibrium in an ex post individually rational query auction can only be ex post efficient when the running timeof the auction is infinite for almost all realizations of valuations of the bidders. We also show that this result applies to the general class of bisection auctions. In contrast we show that, when we allow for inefficient allocations with arbitrarily small probability, there is a query auction (to be more specific, a bisection auction) that attains this level of approximate efficiency in equilibrium, while additionally the running time of the auction in equilibrium is finite for all realizations of valuations.mathematical economics;
Negative local resistance caused by viscous electron backflow in graphene
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