6,217 research outputs found
Asymmetric Gaussian steering: when Alice and Bob disagree
Asymmetric steering is an effect whereby an inseparable bipartite system can
be found to be described by either quantum mechanics or local hidden variable
theories depending on which one of Alice or Bob makes the required
measurements. We show that, even with an inseparable bipartite system,
situations can arise where Gaussian measurements on one half are not sufficient
to answer the fundamental question of which theory gives an adequate
description and the whole system must be considered. This phenomenon is
possible because of an asymmetry in the definition of the original
Einstein-Podolsky-Rosen paradox and in this article we show theoretically that
it may be demonstrated, at least in the case where Alice and Bob can only make
Gaussian measurements, using the intracavity nonlinear coupler.Comment: 5 Pages, 4 Figure
The Age Context of Performance Evaluation Decisions
Organizational demography contends that demographic characteristics of individuals, examined at individual, dyadic, group, and organizational levels of analysis, exert significant effects on organizational processes. The purpose of this paper was to test the contextual effects created by the interaction of work group age composition and supervisor age on supervisor evaluations of subordinate performance. Two competing models of age demography were tested. The similarity model predicts that supervisors similar in age to the work group they supervise will issue generally higher performance ratings. The dissimilarity model developed in this paper predicts the opposite. Support was indicated for the dissimilarity model. Implications of the results are discussed
Limited memory solution of complementarity problems arising in video games
We describe the solution of a complementarity problem with limited memory resources. The problem arising from physical simulations occurring within video games. The motivating problem is outlined, along with a simple interior point approach for its solution. Various linear algebra issues arising in the implementation are explored, including preconditioning, ordering and various ways of solving an equivalent augmented system. Alternative approaches are briefly surveyed, and some recommendations for solving these types of problem are given.\ud
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This material is based on research partially supported by the Smith Institute, EPSRC Grant GR/M59044, the National Science Foundation Grant CCR-9972372, the Air Force Office of Scientific Research Grant F49620-01-1-0040, and the Guggenheim Foundation
Safer scoring? Cryptomarkets, social supply and drug market violence
Background: Cryptomarkets are digital platforms that use anonymising software (e.g. Tor) and cryptocurrencies (e.g. Bitcoin) to facilitate trade of goods and services, most notably illicit drugs. Cryptomarkets may reduce systemic violence compared with in-person drug trading because no face-to-face contact is required and disputes can be resolved through a neutral third party. In this paper, we describe the purchasing behaviour of cryptomarket users and then compare the self-reported experiences of threats, violence and other drug-market concerns when obtaining drugs from cryptomarkets with obtaining drugs through friends, known dealers and strangers. Methods: The Global Drug Survey was completed in late 2014 by a self-selected sample who reported accessing drugs through cryptomarkets in the last 12 months (N = 3794). Results: Their median age was 22 years and 82% were male. The drug types most commonly obtained through cryptomarkets were MDMA/Ecstasy (55%), cannabis (43%) and LSD (35%). Cryptomarket users reported using a median of 2 sources in addition to cryptomarkets to access drugs, the most common being in-person friendships (74%), in-person dealers (57%) and open markets/strangers (26%). When asked to nominate the main source they would use if cryptomarkets were unavailable, 49% nominated friends, 34% known dealers and 4% strangers. 'Threats to personal safety' (3%) and 'experiencing physical violence' (1%) were less often reported when using cryptomarkets compared with sourcing through friends (14%; 6%), known dealers (24%; 10%) or strangers (35%; 15%). Concerns about drug impurities and law enforcement were reported more often when using the alternative source, while loss of money, waiting too long and not receiving the product were more often reported when using cryptomarkets. Conclusion: Cryptomarkets are associated with substantially less threats and violence than alternative market types used by cryptomarket customers, even though a large majority of these alternatives were closed networks where violence should be relatively less common
Multi-frequency fine resolution imaging radar instrumentation and data acquisition
Development of a dual polarized L-band radar imaging system to be used in conjunction with the present dual polarized X-band radar is described. The technique used called for heterodyning the transmitted frequency from X-band to L-band and again heterodyning the received L-band signals back to X-band for amplification, detection, and recording
Surpassing the Standard Quantum Limit in an Atom Interferometer with Four-mode Entanglement Produced from Four-Wave Mixing
We theoretically investigate a scheme for atom interferometry that surpasses
the standard quantum limit. A four-wave mixing scheme similar to the recent
experiment performed by Pertot et al. \cite{pertot} is used to generate
sub-shot noise correlations between two modes. These two modes are then
interfered with the remaining two modes in such a way as to surpass the
standard quantum limit, whilst utilising all of the available atoms. Our scheme
can be viewed as using two correlated interferometers. That is, the signal from
each interferometer when looked at individually is classical, but there are
correlations between the two interferometers that allow for the standard
quantum limit to be surpassed.Comment: 7 pages, 5 figure
Cetuximab ameliorates suppressive phenotypes of myeloid antigen presenting cells in head and neck cancer patients
Background: Myeloid-derived suppressor cells (MDSC) and M2 monocytes/macrophages are two types of suppressive myeloid antigen presenting cells that have been shown to promote tumor progression and correlate with poor prognosis in cancer patients. Tumor antigen specific monoclonal antibodies (mAb) have emerged as important agents for cancer therapy. In addition to the direct inhibition of tumor growth, the Fc portions of the therapeutic mAbs, such as the IgG1 portion of the anti-epidermal growth factor receptor (EGFR) mAb cetuximab, might interact with the Fc-gamma receptors (FcγR) on myeloid cells and modulate their suppressive activity. Methods: Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) on the UPCI 08-013 NCT01218048 trial were treated with single-agent cetuximab before surgery. Blood were collected pre- and post-cetuximab treatment to analyze frequency of monocytic MDSC (CD11b+CD14+HLA-DRlo/-), granulocytic MDSC (LIN-CD11b+CD15+) and CD11b+CD14+HLA-DRhi monocytes by flow cytometry. Besides, CD11b+CD14+HLA-DRhi monocytes were sorted for qPCR analysis of IL-10 and IL-12B transcripts. MDSC were generated in vitro with or without coated hIgG1 and tested for suppressive activity in mixed leukocyte reaction (MLR). Naïve monocytes from HNSCC patients co-cultured with tumor cell lines in the presence of cetuximab or hIgG1 were analyzed for M1/2 surface markers and cytokines. Results: We observed significantly increased monocytic MDSC in non-responders and decreased granulocytic MDSC in responders after cetuximab treatment. In addition, circulating CD11b+CD14+HLA-DRhi monocytes of cetuximab responders displayed attenuated M2 polarization, with decreased CD163+ expression and IL-10 transcripts after cetuximab treatment. This beneficial effect appeared to be FcγR dependent, since CD16 ligation reproduced the reversal of suppressive activity of MDSC in vitro. CD14+ naïve monocytes from the co-cultures of tumor cells, cetuximab and HNSCC patient PBMC or purified monocytes were skewed to an M1-like phenotype, with increased expression of HLA-DR, CD86 and production of IL-12 p70. Likewise, reduced M2 features (expression of CD163 and production of IL-10) were found after crosslinking CD16 on the surface of monocytes to cetuximab-coated tumor cells. Conclusion: Our studies demonstrate a novel function of cetuximab in ameliorating suppressive phenotypes of FcγR bearing myeloid cells in cancer patients, which is associated with better clinical outcome of cetuximab-treated patients. Clinical trial registry: # NCT01218048. Registered 7 October 2010
A biophysical model of prokaryotic diversity in geothermal hot springs
Recent field investigations of photosynthetic bacteria living in geothermal
hot spring environments have revealed surprisingly complex ecosystems, with an
unexpected level of genetic diversity. One case of particular interest involves
the distribution along hot spring thermal gradients of genetically distinct
bacterial strains that differ in their preferred temperatures for reproduction
and photosynthesis. In such systems, a single variable, temperature, defines
the relevant environmental variation. In spite of this, each region along the
thermal gradient exhibits multiple strains of photosynthetic bacteria adapted
to several distinct thermal optima, rather than the expected single thermal
strain adapted to the local environmental temperature. Here we analyze
microbiology data from several ecological studies to show that the thermal
distribution field data exhibit several universal features independent of
location and specific bacterial strain. These include the distribution of
optimal temperatures of different thermal strains and the functional dependence
of the net population density on temperature. Further, we present a simple
population dynamics model of these systems that is highly constrained by
biophysical data and by physical features of the environment. This model can
explain in detail the observed diversity of different strains of the
photosynthetic bacteria. It also reproduces the observed thermal population
distributions, as well as certain features of population dynamics observed in
laboratory studies of the same organisms
Molecular and mass spectroscopic analysis of isotopically labeled organic residues
Experimental studies aimed at understanding the evolution of complex organic molecules on interstellar grains were performed. The photolysis of frozen gas mixtures of various compositions containing H2O, CO, NH3, and CH4 was studied. These species were chosen because of their astrophysical importance as deducted from observational as well as theoretical studies of ice mantles on interstellar grains. These ultraviolet photolyzed ices were warmed up in order to produce refractory organic molecules like the ones formed in molecular clouds when the icy mantles are being irradiated and warmed up either by a nearby stellar source or impulsive heating. The laboratory studies give estimates of the efficiency of production of such organic material under interstellar conditions. It is shown that the gradual carbonization of organic mantles in the diffuse cloud phase leads to higher and higher visual absorptivity - yellow residues become brown in the laboratory. The obtained results can be applied to explaining the organic components of comets and their relevance to the origin of life
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