677 research outputs found

    Strichartz estimates for the Schroedinger equation on non-rectangular two-dimensional tori

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    We propose a conjecture for long time Strichartz estimates on generic (non-rectangular) flat tori. We proceed to partially prove it in dimension 2. Our arguments involve on the one hand Weyl bounds; and on the other hands bounds on the number of solutions of Diophantine problems.Comment: 28 page

    Localism vs. Individualism for the Scientific Realism Debate

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    Localism is the view that the unit of evaluation in the scientific realism debate is a single scientific discipline, sub-discipline, or claim, whereas individualism is the view that the unit of evaluation is a single scientific theory. Localism is compatible, while individualism is not, with a local pessimistic induction and a local selective induction. Asay (2016) presents several arguments to support localism and undercut globalism, according to which the unit of evaluation is the set of all scientific disciplines. I argue that some of his arguments clash with localism as well as with globalism and support individualism, and that individualism goes hand in hand, while localism does not, with the basic rule of how to evaluate an argument

    Evolving localizations in reaction-diffusion cellular automata

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    We consider hexagonal cellular automata with immediate cell neighbourhood and three cell-states. Every cell calculates its next state depending on the integral representation of states in its neighbourhood, i.e. how many neighbours are in each one state. We employ evolutionary algorithms to breed local transition functions that support mobile localizations (gliders), and characterize sets of the functions selected in terms of quasi-chemical systems. Analysis of the set of functions evolved allows to speculate that mobile localizations are likely to emerge in the quasi-chemical systems with limited diffusion of one reagent, a small number of molecules is required for amplification of travelling localizations, and reactions leading to stationary localizations involve relatively equal amount of quasi-chemical species. Techniques developed can be applied in cascading signals in nature-inspired spatially extended computing devices, and phenomenological studies and classification of non-linear discrete systems.Comment: Accepted for publication in Int. J. Modern Physics

    Exo-zodiacal disk mapper: a space interferometer to detect and map zodiacal disks around nearby stars

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    We propose a concept for a space mission designed to make a survey of potential zodiacal dust disks around nearby stars in the mid-IR. We show that a 10-meter baseline nulling interferometer with two 0.6-meter apertures located in a 1 X 1 AU heliocentric orbit would allow for the survey of about 400 stars in the solar neighborhood and permit a first order determination of the disk inclination and of the dust density and temperature radius dependence. The high dynamic range of the instrument may also be used to study an additional astrophysical phenomena. Beyond its own scientific merit, such a mission would also serve as a technological precursor to a larger interferometer of the type being considered for the detection of earth-like planets

    Assessing Medication Adherence and Healthcare Utilization and Cost Patterns Among Hospital-Discharged Patients with Schizoaffective Disorder

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    BACKGROUND: Hospital-discharged patients with schizoaffective disorder have a high risk of re-hospitalization. However, limited data exist evaluating critical post-discharge periods during which the risk of re-hospitalization is significant. OBJECTIVE: Among hospital-discharged patients with schizoaffective disorder, we assessed pharmacotherapy adherence and healthcare utilization and costs during sequential 60-day clinical periods before schizoaffective disorder-related hospitalization and post-hospital discharge. METHODS: From the MarketScan(®) Medicaid database (2004–2008), we identified patients (≥18 years) with a schizoaffective disorder-related inpatient admission. Study measures including medication adherence and healthcare utilization and costs were assessed during sequential preadmission and post-discharge periods. We conducted univariate and multivariable regression analyses to compare schizoaffective disorder-related and all-cause healthcare utilization and costs (in 2010 US dollars) between each adjacent 60-day post-discharge periods. No adjustment was made for multiplicity. RESULTS: We identified 1,193 hospital-discharged patients with a mean age of 41 years. The mean medication adherence rate was 46 % during the 60-day period prior to index inpatient admission, which improved to 80 % during the 60-day post-discharge period. Following hospital discharge, schizoaffective disorder-related healthcare costs were significantly greater during the initial 60-day period compared with the 61- to 120-day post-discharge period (mean US2,370vsUS2,370 vs US1,765; p < 0.001), with rehospitalization (36 %) and pharmacy (40 %) accounting for over three-fourths of the initial 60-day period costs. Compared with the initial 60-day post-discharge period, both all-cause and schizoaffective disorder-related costs declined during the 61- to 120-day post-discharge period and remained stable for the remaining post-discharge periods (days 121–365). CONCLUSIONS: We observed considerably lower (46 %) adherence during 60 days prior to the inpatient admission; in comparison, adherence for the overall 6-month period was 8 % (54 %) higher. Our study findings suggest that both short-term (e.g., 60 days) and long-term (e.g., 6–12 months) medication adherence likely are important characteristics to examine among patients with schizoaffective disorder and help provide a more holistic view of patients’ adherence patterns. Furthermore, we observed a high rate of rehospitalization and greater healthcare costs during the initial 60-day period post-discharge among patients with schizoaffective disorder. Further research is required to better understand and manage transitional care after discharge (e.g., monitor adherence), which may help reduce the likelihood of rehospitalization and the associated downstream costs. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s40258-014-0095-8) contains supplementary material, which is available to authorized users

    Strichartz estimates for the Schroedinger equation on non-rectangular two-dimensional tori

    Get PDF
    We propose a conjecture for long time Strichartz estimates on generic (non-rectangular) at tori. We proceed to partially prove it in dimension 2. Our arguments involve on the one hand Weyl bounds; and on the other hands bounds on the number of solutions of Diophantine problems

    Scientific challenges and present capabilities in underwater robotic vehicle design and navigation for oceanographic exploration under-ice.

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    This paper reviews the scientific motivation and challenges, development, and use of underwater robotic vehicles designed for use in ice-covered waters, with special attention paid to the navigation systems employed for under-ice deployments. Scientific needs for routine access under fixed and moving ice by underwater robotic vehicles are reviewed in the contexts of geology and geophysics, biology, sea ice and climate, ice shelves, and seafloor mapping. The challenges of under-ice vehicle design and navigation are summarized. The paper reviews all known under-ice robotic vehicles and their associated navigation systems, categorizing them by vehicle type (tethered, untethered, hybrid, and glider) and by the type of ice they were designed for (fixed glacial or sea ice and moving sea ice). © 2020 by the authors

    Prediction of Graft-Versus-Host Disease in Humans by Donor Gene-Expression Profiling

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    BACKGROUND: Graft-versus-host disease (GVHD) results from recognition of host antigens by donor T cells following allogeneic hematopoietic cell transplantation (AHCT). Notably, histoincompatibility between donor and recipient is necessary but not sufficient to elicit GVHD. Therefore, we tested the hypothesis that some donors may be “stronger alloresponders” than others, and consequently more likely to elicit GVHD. METHODS AND FINDINGS: To this end, we measured the gene-expression profiles of CD4(+) and CD8(+) T cells from 50 AHCT donors with microarrays. We report that pre-AHCT gene-expression profiling segregates donors whose recipient suffered from GVHD or not. Using quantitative PCR, established statistical tests, and analysis of multiple independent training-test datasets, we found that for chronic GVHD the “dangerous donor” trait (occurrence of GVHD in the recipient) is under polygenic control and is shaped by the activity of genes that regulate transforming growth factor-β signaling and cell proliferation. CONCLUSIONS: These findings strongly suggest that the donor gene-expression profile has a dominant influence on the occurrence of GVHD in the recipient. The ability to discriminate strong and weak alloresponders using gene-expression profiling could pave the way to personalized transplantation medicine
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