237 research outputs found

    (Total) Vector Domination for Graphs with Bounded Branchwidth

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    Given a graph G=(V,E)G=(V,E) of order nn and an nn-dimensional non-negative vector d=(d(1),d(2),,d(n))d=(d(1),d(2),\ldots,d(n)), called demand vector, the vector domination (resp., total vector domination) is the problem of finding a minimum SVS\subseteq V such that every vertex vv in VSV\setminus S (resp., in VV) has at least d(v)d(v) neighbors in SS. The (total) vector domination is a generalization of many dominating set type problems, e.g., the dominating set problem, the kk-tuple dominating set problem (this kk is different from the solution size), and so on, and its approximability and inapproximability have been studied under this general framework. In this paper, we show that a (total) vector domination of graphs with bounded branchwidth can be solved in polynomial time. This implies that the problem is polynomially solvable also for graphs with bounded treewidth. Consequently, the (total) vector domination problem for a planar graph is subexponential fixed-parameter tractable with respectto kk, where kk is the size of solution.Comment: 16 page

    Renewable Energy

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    This chapter presents an in-depth examination of major renewable energy technologies, including their installed capacity and energy supply in 2009 , the current state of market and technology development, their economic and financial feasibility in 2009 and in the near future, as well as major issues they may face relative to their sustainability or implementation. Renewable energy sources have been important for humankind since the beginning of civilization. For centuries, biomass has been used for heating, cooking, steam generation, and power production; solar energy has been used for heating and drying; geothermal energy has been used for hot water supplies; hydropower, for movement; and wind energy, for pumping and irrigation. For many decades renewable energy sources have also been used to produce electricity or other modern energy carriers

    Trends in the use of disease-modifying therapies among reproductive-aged women with multiple sclerosis in the United States from 2010 to 2019

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    Purpose: Multiple sclerosis (MS) is a chronic disease of the central nervous system that disproportionately affects women, with typical onset during reproductive age. Several disease-modifying therapies (DMTs) are FDA-approved to slow disease progression, but are not indicated for use during pregnancy. Our objective was to describe trends over time (2010–2019) in monthly point prevalence of DMT use among reproductive-age women, overall and by generic name. Methods: This study used administrative claims data from the US during 2009–2019 to identify women age 15–44 with MS and continuous insurance coverage for ≥12 months. DMTs were identified using prescription fills and procedural claims for alemtuzumab, daclizumab, dimethyl fumarate, fingolimod, glatiramer acetate, interferon beta, mitoxantrone, natalizumab, ocrelizumab, and teriflunomide. Monthly prevalent use was defined as ≥1 days' supply of a DMT in the month. Age- and region-standardized monthly prevalence was estimated nonparametrically. Results: Among 42 281 reproductive-aged women over 818 179 person-months, DMT use increased from a minimum monthly prevalence of 49.3% (February, 2011) to a maximum of 58.7% (April, 2019). In 2010, prevalence of injectable DMTs was 43.1% compared to 2.5% for oral DMTs; by 2014, however, oral DMTs (26.5%) surpassed injectable DMTs (23.7%) as the most common route of administration. In the most recent data available (December, 2019), the most common DMTs were dimethyl fumarate, glatiramer acetate, and fingolimod. Conclusions: DMT use among reproductive-aged women has rapidly evolved during the past decade. Collaborative treatment decision making between women with MS and clinicians may help optimize MS care and improve DMT uptake during reproductive years

    The Timing, the Treatment, the Question: Comparison of Epidemiologic Approaches to Minimize Immortal Time Bias in Real-World Data Using a Surgical Oncology Example

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    Background: Studies evaluating the effects of cancer treatments are prone to immortal time bias that, if unaddressed, can lead to treatments appearing more beneficial than they are. Methods: To demonstrate the impact of immortal time bias, we compared results across several analytic approaches (dichotomous exposure, dichotomous exposure excluding immortal time, time-varying exposure, landmark analysis, clone-censor-weight method), using surgical resection among women with metastatic breast cancer as an example. All adult women diagnosed with incident metastatic breast cancer from 2013–2016 in the National Cancer Database were included. To quantify immortal time bias, we also conducted a simulation study where the “true” relationship between surgical resection and mortality was known. Results: 24,329 women (median age 61, IQR 51–71) were included, and 24% underwent surgical resection. The largest association between resection and mortality was observed when using a dichotomized exposure [HR, 0.54; 95% confidence interval (CI), 0.51–0.57], followed by dichotomous with exclusion of immortal time (HR, 0.62; 95% CI, 0.59–0.65). Results from the time-varying exposure, landmark, and clone-censor-weight method analyses were closer to the null (HR, 0.67–0.84). Results from the plasmode simulation found that the time-varying exposure, landmark, and clone-censor-weight method models all produced unbiased HRs (bias -0.003 to 0.016). Both standard dichotomous exposure (HR, 0.84; bias, -0.177) and dichotomous with exclusion of immortal time (HR, 0.93; bias, -0.074) produced meaningfully biased estimates. Conclusions: Researchers should use time-varying exposures with a treatment assessment window or the clone-censor-weight method when immortal time is present. Impact: Using methods that appropriately account for immortal time will improve evidence and decision-making from research using real-world data

    Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

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    The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

    Missing data approaches in longitudinal studies of aging: A case example using the National Health and Aging Trends Study

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    Purpose Missing data is a key methodological consideration in longitudinal studies of aging. We described missing data challenges and potential methodological solutions using a case example describing five-year frailty state transitions in a cohort of older adults. Methods We used longitudinal data from the National Health and Aging Trends Study, a nationally-representative cohort of Medicare beneficiaries. We assessed the five components of the Fried frailty phenotype and classified frailty based on their number of components (robust: 0, prefrail: 1–2, frail: 3–5). One-, two-, and five-year frailty state transitions were defined as movements between frailty states or death. Missing frailty components were imputed using hot deck imputation. Inverse probability weights were used to account for potentially informative loss-to-follow-up. We conducted scenario analyses to test a range of assumptions related to missing data. Results Missing data were common for frailty components measured using physical assessments (walking speed, grip strength). At five years, 36% of individuals were lost-to-follow-up, differentially with respect to baseline frailty status. Assumptions for missing data mechanisms impacted inference regarding individuals improving or worsening in frailty. Conclusions Missing data and loss-to-follow-up are common in longitudinal studies of aging. Robust epidemiologic methods can improve the rigor and interpretability of aging-related research

    A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector

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    A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance

    Search for invisible Higgs boson decays in vector boson fusion at √s = 13 TeV with the ATLAS detector

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    We report a search for Higgs bosons that are produced via vector boson fusion and subsequently decay into invisible particles. The experimental signature is an energetic jet pair with invariant mass of O(1) TeV and O(100) GeV missing transverse momentum. The analysis uses 36.1 fb−1 of pp collision data at √s=13 TeV recorded by the ATLAS detector at the LHC. In the signal region the 2252 observed events are consistent with the background estimation. Assuming a 125 GeV scalar particle with Standard Model cross sections, the upper limit on the branching fraction of the Higgs boson decay into invisible particles is 0.37 at 95% confidence level where 0.28 was expected. This limit is interpreted in Higgs portal models to set bounds on the wimp–nucleon scattering cross section. We also consider invisible decays of additional scalar bosons with masses up to 3 TeV for which the upper limits on the cross section times branching fraction are in the range of 0.3–1.7 pb

    Observation of photon-induced W<sup>+</sup>W<sup>−</sup> production in pp collisions at √s=13 TeV using the ATLAS detector

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    This letter reports the observation of photon-induced production of W-boson pairs, γγ→ WW. The analysis uses 139 fb-1 of LHC proton-proton collision data taken at √s=13 TeV recorded by the ATLAS experiment during the years 2015-2018. The measurement is performed selecting one electron and one muon, corresponding to the decay of the diboson system as WW→e±νμ∓ν final state. The background-only hypothesis is rejected with a significance of well above 5 standard deviations consistent with the expectation from Monte Carlo simulation. A cross section for the γγ→ WW process of 3.13±0.31(stat.)±0.28(syst.) fb is measured in a fiducial volume close to the acceptance of the detector, by requiring an electron and a muon of opposite signs with large dilepton transverse momentum and exactly zero additional charged particles. This is found to be in agreement with the Standard Model prediction
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