5,225 research outputs found

    Fine particulate matter pollution and risk of community-acquired sepsis

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    While air pollution has been associated with health complications, its effect on sepsis risk is unknown. We examined the association between fine particulate matter (PM2.5) air pollution and risk of sepsis hospitalization. We analyzed data from the 30,239 community-dwelling adults in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort linked with satellite-derived measures of PM2.5 data. We defined sepsis as a hospital admission for a serious infection with ≥2 systemic inflammatory response (SIRS) criteria. We performed incidence density sampling to match sepsis cases with 4 controls by age (±5 years), sex, and race. For each matched group we calculated mean daily PM2.5 exposures for short-term (30-day) and long-term (one-year) periods preceding the sepsis event. We used conditional logistic regression to evaluate the association between PM2.5 exposure and sepsis, adjusting for education, income, region, temperature, urbanicity, tobacco and alcohol use, and medical conditions. We matched 1386 sepsis cases with 5544 non-sepsis controls. Mean 30-day PM2.5 exposure levels (Cases 12.44 vs. Controls 12.34 µg/m3; p = 0.28) and mean one-year PM2.5 exposure levels (Cases 12.53 vs. Controls 12.50 µg/m3; p = 0.66) were similar between cases and controls. In adjusted models, there were no associations between 30-day PM2.5 exposure levels and sepsis (4th vs. 1st quartiles OR: 1.06, 95% CI: 0.85–1.32). Similarly, there were no associations between one-year PM2.5 exposure levels and sepsis risk (4th vs. 1st quartiles OR: 0.96, 95% CI: 0.78–1.18). In the REGARDS cohort, PM2.5 air pollution exposure was not associated with risk of sepsis

    Strategic Choice of Channel Structure in an Oligopoly

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    The traditional wisdom holds that the benefits of a decentralized channel structure arise from downstream competitive relationships. In contrast, Arya and Mittendorf (2007) showed that the value of decentralization can also arise from upstream interaction when the downstream firm conveys internal strife (decentralization) to an upstream external supplier. This paper extends the single firm centralization-decentralization choice model of Arya and Mittendorf (2007) to a strategic choice model in which all downstream competitors play a strategic centralization-decentralization game. We demonstrate that whether the main conclusions in the context of non-strategic choice of channel structure continue to hold when all firms play a centralization-decentralization game depends critically on the market structure of the upstream input market. Specifically, the conclusions are valid if all firms have exclusive upstream input suppliers but not so if the upstream input market is monopolized. Thus, whether the value of decentralization can arise from upstream interaction depends critically on the market structure of the upstream market

    The random case of Conley's theorem: III. Random semiflow case and Morse decomposition

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    In the first part of this paper, we generalize the results of the author \cite{Liu,Liu2} from the random flow case to the random semiflow case, i.e. we obtain Conley decomposition theorem for infinite dimensional random dynamical systems. In the second part, by introducing the backward orbit for random semiflow, we are able to decompose invariant random compact set (e.g. global random attractor) into random Morse sets and connecting orbits between them, which generalizes the Morse decomposition of invariant sets originated from Conley \cite{Con} to the random semiflow setting and gives the positive answer to an open problem put forward by Caraballo and Langa \cite{CL}.Comment: 21 pages, no figur

    Polarization Dependence of Born Effective Charge and Dielectric Constant in KNbO3_3

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    The Born effective charge Z^{*} and dielectric tensor \epsilon_{\infty} of KNbO_3 are found to be very sensitive to the atomic geometry, changing by as much as 27% between the paraelectric cubic and ferroelectric tetragonal and rhombohedral phases. Subtracting the bare ionic contribution reveals changes of the dynamic component of Z^{*} as large as 50%, for atomic displacements that are typically only a few percent of the lattice constant. Z^{*}, \epsilon_{\infty} and all phonon frequencies at the Brillouin zone center were calculated using the {\it ab initio} linearized augmented plane-wave linear response method with respect to the reference cubic, experimental tetragonal, and theoretically determined rhombohedral ground state structures. The ground state rhombohedral structure of KNbO_3 was determined by minimizing the forces on the relaxed atoms. By contrast with the cubic structure, all zone center phonon modes of the rhombohedral structure are stable and their frequencies are in good agreement with experiment. In the tetragonal phase, one of the soft zone center modes in the cubic phase is stablized. In view of the small atomic displacements involved in the ferroelectric transitions, it is evident that not only the soft mode frequencies but also the Born effective charge and dielectric constants are very sensitive to the atomic geometry.Comment: 26 pages, revtex, no figures; to appear in Phys. Rev. B15 (Oct.), 199

    Cluster Masses Accounting for Structure along the Line of Sight

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    Weak gravitational lensing of background galaxies by foreground clusters offers an excellent opportunity to measure cluster masses directly without using gas as a probe. One source of noise which seems difficult to avoid is large scale structure along the line of sight. Here I show that, by using standard map-making techniques, one can minimize the deleterious effects of this noise. The resulting uncertainties on cluster masses are significantly smaller than when large scale structure is not properly accounted for, although still larger than if it was absent altogether.Comment: 5 pages, 5 figure

    Pressure Dependence of Born Effective Charges, Dielectric Constant and Lattice Dynamics in SiC

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    The pressure dependence of the Born effective charge, dielectric constant and zone-center LO and TO phonons have been determined for 3C3C-SiC by a linear response method based on the linearized augmented plane wave calculations within the local density approximation. The Born effective charges are found to increase nearly linearly with decreasing volume down to the smallest volume studied, V/V0=0.78V/V_0=0.78, corresponding to a pressure of about 0.8 Mbar. This seems to be in contradiction with the conclusion of the turnover behavior recently reported by Liu and Vohra [Phys.\ Rev.\ Lett.\ {\bf 72}, 4105 (1994)] for 6H6H-SiC. Reanalyzing their procedure to extract the pressure dependence of the Born effective charges, we suggest that the turnover behavior they obtained is due to approximations in the assumed pressure dependence of the dielectric constant ε\varepsilon_\infty, the use of a singular set of experimental data for the equation of state, and the uncertainty in measured phonon frequencies, especially at high pressure.Comment: 25 pages, revtex, 5 postscript figures appended, to be published in Phys. Rev.

    CRLX101, a Nanoparticle–Drug Conjugate Containing Camptothecin, Improves Rectal Cancer Chemoradiotherapy by Inhibiting DNA Repair and HIF1α

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    Novel agents are needed to improve chemoradiotherapy for locally advanced rectal cancer. In this study, we assessed the ability of CRLX101, an investigational nanoparticle-drug conjugate containing the payload camptothecin (CPT), to improve therapeutic responses as compared to standard chemotherapy. CRLX101 was evaluated as a radiosensitizer in colorectal cancer cell lines and murine xenograft models. CRLX101 was as potent as CPT in vitro in its ability to radiosensitize cancer cells. Evaluations in vivo demonstrated that the addition of CRLX101 to standard chemoradiotherapy significantly increased therapeutic efficacy by inhibiting DNA repair and HIF-1α pathway activation in tumor cells. Notably, CRLX101 was more effective than oxaliplatin at enhancing the efficacy of chemoradiotherapy, with CRLX101 and 5-fluorouracil (5-FU) producing the highest therapeutic efficacy. Gastrointestinal toxicity was also significantly lower for CRLX101 compared to CPT when combined with radiotherapy. Our results offer a preclinical proof of concept for CRLX101 as a modality to improve the outcome of neoadjuvant chemoradiotherapy for rectal cancer treatment, in support of ongoing clinical evaluation of this agent (LCC1315 {"type":"clinical-trial","attrs":{"text":"NCT02010567","term_id":"NCT02010567"}}NCT02010567)

    Two-photon Lithography for 3D Magnetic Nanostructure Fabrication

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    Ferromagnetic materials have been utilised as recording media within data storage devices for many decades. Confinement of the material to a two dimensional plane is a significant bottleneck in achieving ultra-high recording densities and this has led to the proposition of three dimensional (3D) racetrack memories that utilise domain wall propagation along nanowires. However, the fabrication of 3D magnetic nanostructures of complex geometry is highly challenging and not easily achievable with standard lithography techniques. Here, by using a combination of two-photon lithography and electrochemical deposition, we show a new approach to construct 3D magnetic nanostructures of complex geometry. The magnetic properties are found to be intimately related to the 3D geometry of the structure and magnetic imaging experiments provide evidence of domain wall pinning at a 3D nanostructured junction

    Anomalous Heat Conduction and Anomalous Diffusion in Low Dimensional Nanoscale Systems

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    Thermal transport is an important energy transfer process in nature. Phonon is the major energy carrier for heat in semiconductor and dielectric materials. In analogy to Ohm's law for electrical conductivity, Fourier's law is a fundamental rule of heat transfer in solids. It states that the thermal conductivity is independent of sample scale and geometry. Although Fourier's law has received great success in describing macroscopic thermal transport in the past two hundreds years, its validity in low dimensional systems is still an open question. Here we give a brief review of the recent developments in experimental, theoretical and numerical studies of heat transport in low dimensional systems, include lattice models, nanowires, nanotubes and graphenes. We will demonstrate that the phonon transports in low dimensional systems super-diffusively, which leads to a size dependent thermal conductivity. In other words, Fourier's law is breakdown in low dimensional structures

    Aurora kinase A drives the evolution of resistance to third-generation EGFR inhibitors in lung cancer.

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    Although targeted therapies often elicit profound initial patient responses, these effects are transient due to residual disease leading to acquired resistance. How tumors transition between drug responsiveness, tolerance and resistance, especially in the absence of preexisting subclones, remains unclear. In epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma cells, we demonstrate that residual disease and acquired resistance in response to EGFR inhibitors requires Aurora kinase A (AURKA) activity. Nongenetic resistance through the activation of AURKA by its coactivator TPX2 emerges in response to chronic EGFR inhibition where it mitigates drug-induced apoptosis. Aurora kinase inhibitors suppress this adaptive survival program, increasing the magnitude and duration of EGFR inhibitor response in preclinical models. Treatment-induced activation of AURKA is associated with resistance to EGFR inhibitors in vitro, in vivo and in most individuals with EGFR-mutant lung adenocarcinoma. These findings delineate a molecular path whereby drug resistance emerges from drug-tolerant cells and unveils a synthetic lethal strategy for enhancing responses to EGFR inhibitors by suppressing AURKA-driven residual disease and acquired resistance
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