28 research outputs found

    How does the electromagnetic field couple to gravity, in particular to metric, nonmetricity, torsion, and curvature?

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    The coupling of the electromagnetic field to gravity is an age-old problem. Presently, there is a resurgence of interest in it, mainly for two reasons: (i) Experimental investigations are under way with ever increasing precision, be it in the laboratory or by observing outer space. (ii) One desires to test out alternatives to Einstein's gravitational theory, in particular those of a gauge-theoretical nature, like Einstein-Cartan theory or metric-affine gravity. A clean discussion requires a reflection on the foundations of electrodynamics. If one bases electrodynamics on the conservation laws of electric charge and magnetic flux, one finds Maxwell's equations expressed in terms of the excitation H=(D,H) and the field strength F=(E,B) without any intervention of the metric or the linear connection of spacetime. In other words, there is still no coupling to gravity. Only the constitutive law H= functional(F) mediates such a coupling. We discuss the different ways of how metric, nonmetricity, torsion, and curvature can come into play here. Along the way, we touch on non-local laws (Mashhoon), non-linear ones (Born-Infeld, Heisenberg-Euler, Plebanski), linear ones, including the Abelian axion (Ni), and find a method for deriving the metric from linear electrodynamics (Toupin, Schoenberg). Finally, we discuss possible non-minimal coupling schemes.Comment: Latex2e, 26 pages. Contribution to "Testing Relativistic Gravity in Space: Gyroscopes, Clocks, Interferometers ...", Proceedings of the 220th Heraeus-Seminar, 22 - 27 August 1999 in Bad Honnef, C. Laemmerzahl et al. (eds.). Springer, Berlin (2000) to be published (Revised version uses Springer Latex macros; Sec. 6 substantially rewritten; appendices removed; the list of references updated

    Charm and hidden charm scalar mesons in the nuclear medium

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    We study the renormalization of the properties of low lying charm and hidden charm scalar mesons in a nuclear medium, concretely of the D_{s0}(2317) and the theoretical hidden charm state X(3700). We find that for the D_{s0}(2317), with negligible width at zero density, the width becomes about 100 MeV at normal nuclear matter density, while in the case of the X(3700) the width becomes as large as 200 MeV. We discuss the origin of this new width and trace it to reactions occurring in the nucleus, while offering a guideline for future experiments testing these changes. We also show how those medium modifications will bring valuable information on the nature of the scalar resonances and the mechanisms of the interaction of D mesons with nucleons and nuclei

    Vascular Remodeling in Health and Disease

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    The term vascular remodeling is commonly used to define the structural changes in blood vessel geometry that occur in response to long-term physiologic alterations in blood flow or in response to vessel wall injury brought about by trauma or underlying cardiovascular diseases.1, 2, 3, 4 The process of remodeling, which begins as an adaptive response to long-term hemodynamic alterations such as elevated shear stress or increased intravascular pressure, may eventually become maladaptive, leading to impaired vascular function. The vascular endothelium, owing to its location lining the lumen of blood vessels, plays a pivotal role in regulation of all aspects of vascular function and homeostasis.5 Thus, not surprisingly, endothelial dysfunction has been recognized as the harbinger of all major cardiovascular diseases such as hypertension, atherosclerosis, and diabetes.6, 7, 8 The endothelium elaborates a variety of substances that influence vascular tone and protect the vessel wall against inflammatory cell adhesion, thrombus formation, and vascular cell proliferation.8, 9, 10 Among the primary biologic mediators emanating from the endothelium is nitric oxide (NO) and the arachidonic acid metabolite prostacyclin [prostaglandin I2 (PGI2)], which exert powerful vasodilatory, antiadhesive, and antiproliferative effects in the vessel wall

    Utilizing Data Mining for Predictive Modeling of Colorectal Cancer using Electronic Medical Records

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    Colorectal cancer (CRC) is a relatively common cause of death around the globe. Predictive models for the development of CRC could be highly valuable and could facilitate an early diagnosis and increased survival rates. Currently available predictive models are improving, but do not fully utilize the wealth of data available about patients in routine care nor do they take advantage of the developments in the area of data mining. In this paper, a first attempt to generate a predictive model using the CHAID decision tree learner based on anonymously extracted Electronic Medical Records is reported, showing an area under the curve (AUC) of .839 for the adult population and .702 for the age group between 55 and 75. © 2014 Springer International Publishing

    Moving towards Hepatitis C microelimination among people living with Human Immunodeficiency Virus in Australia: the CEASE study

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    Background: Microelimination of hepatitis C virus (HCV) among people living with human immunodeficiency virus (HIV) may be feasible in Australia, given unrestricted access to direct-acting antiviral (DAA) therapy from 2016. Our aim was to evaluate progress towards elimination goals within HIV/HCV-coinfected adults in Australia following universal DAA access. Methods: The CEASE prospective cohort study enrolled adults with HIV/HCV, irrespective of viremic status, from 14 primary and tertiary clinics in Australia. Annual and cumulative HCV treatment uptake, outcome, and HCV RNA prevalence were evaluated, with follow-up through May 2018 (median follow-up, 2.63 years). Factors associated with DAA uptake were analyzed. Results: Between July 2014 and March 2017, 402 participants who were HIV/HCV antibody positive were enrolled (95% male [80% gay and bisexual men,], 13% cirrhosis, 80% history of injecting drug use [39% currently injecting]). Following universal DAA access, annual HCV treatment uptake in those eligible increased from 7% and 11% per year in 2014 and 2015, respectively, to 80% in 2016. By 2018, cumulative HCV treatment uptake in those ever eligible for treatment was 91% (336/371). HCV viremic prevalence declined from 82% (95% CI, 78–86%) in 2014 to 8% (95% CI, 6–12%) in 2018. Reinfection was reported in only 5 participants for a reinfection incidence of 0.81 per 100 person-years (95% CI, 0.34–1.94). Conclusions: High uptake and effectiveness of unrestricted DAA therapy in Australia have permitted rapid treatment scale-up, with a dramatic reduction in HCV infection burden and low reinfection rate among people living with HIV, suggesting that microelimination is feasible.Marianne Martinello, Jasmine Yee, Sofia R. Bartlett, Phillip Read, David Baker, Jeffrey J. Post, Robert Finlayson, Mark Bloch, Joseph Doyle, David Shaw, Margaret Hellard, Kathy Petoumenos, Lanni Lin, Philippa Marks, Tanya Applegate, Gregory J. Dore, and Gail V. Matthews (for the CEASE study team
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