196 research outputs found

    Strong Gravitational Lensing and Dark Energy Complementarity

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    In the search for the nature of dark energy most cosmological probes measure simple functions of the expansion rate. While powerful, these all involve roughly the same dependence on the dark energy equation of state parameters, with anticorrelation between its present value w_0 and time variation w_a. Quantities that have instead positive correlation and so a sensitivity direction largely orthogonal to, e.g., distance probes offer the hope of achieving tight constraints through complementarity. Such quantities are found in strong gravitational lensing observations of image separations and time delays. While degeneracy between cosmological parameters prevents full complementarity, strong lensing measurements to 1% accuracy can improve equation of state characterization by 15-50%. Next generation surveys should provide data on roughly 10^5 lens systems, though systematic errors will remain challenging.Comment: 7 pages, 5 figure

    Dynamics of Void and its Shape in Redshift Space

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    We investigate the dynamics of a single spherical void embedded in a Friedmann-Lema\^itre universe, and analyze the void shape in the redshift space. We find that the void in the redshift space appears as an ellipse shape elongated in the direction of the line of sight (i.e., an opposite deformation to the Kaiser effect). Applying this result to observed void candidates at the redshift z~1-2, it may provide us with a new method to evaluate the cosmological parameters, in particular the value of a cosmological constant.Comment: 19 pages, 11 figure

    Time-Varying Dark Energy Constraints From the Latest SN Ia, BAO and SGL

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    Based on the latest SNe Ia data provided by Hicken et al. (2009) with using MLCS17 light curve fitter, together with the Baryon Acoustic Oscillation(BAO) and strong gravitational lenses(SGL), we investigate the constraints on the dark energy equation-of-state parameter ww in the flat universe, especially for the time-varying case w(z)=w0+wzz/(1+z)w(z)=w_0+w_zz/(1+z). The constraints from SNe data alone are found to be: (a) (ΩM,w)=(0.358,1.09)(\Omega_M, w)=(0.358, -1.09) as the best-fit results; (b) (w0,wz)=(0.730.97+0.23,0.8410.34+1.66)(w_0, w_z)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34}) for the two parameters in the time-varying case after marginalizing the parameter ΩM\Omega_M; (c) the likelihood of parameter wzw_z has a high non-Gaussian distribution; (d) an extra restriction on ΩM\Omega_M is necessary to improve the constraint of the SNe Ia data on the parameters (w0w_0, wzw_z). A joint analysis of SNe Ia data and BAO is made to break the degeneracy between ww and ΩM\Omega_M, and leads to the interesting maximum likelihoods w0=0.94w_0 = -0.94 and wz=0w_z = 0. When marginalizing the parameter ΩM\Omega_M, the fitting results are found to be (w0,wz)=(0.950.18+0.45,0.410.96+0.79)(w_0, w_z)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96}). After adding the splitting angle statistic of SGL data, a consistent constraint is obtained (ΩM,w)=(0.298,0.907)(\Omega_M, w)=(0.298, -0.907) and the constraints on time-varying dark energy are further improved to be (w0,wz)=(0.920.10+0.14,0.350.54+0.47)(w_0, w_z) = (-0.92^{+0.14}_{-0.10}, 0.35^{+0.47}_{-0.54}), which indicates that the phantom type models are disfavored.Comment: 24 pages, 9 figures, to be published in JCA

    Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

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    Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

    Prospects for the Improvement of Energy Performance in Agroindustry Using Phase Change Materials

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    This work was partially supported by the Fundação para a Ciência e Tecnologia, UIDB/00066/2020 (CTS – Center of Technology and Systems).The use of Phase Change Materials (PCMs), able to store latent heat, represents an opportunity to improve energy efficiency in the agroindustry by means of thermal energy storage. PCMs provide higher energy density then sensible heat storage mediums, thus paving the way to multiple applications, like supporting the integration of renewables or allowing for new storage architectures, decentralized and directly installed in the chain production equipment, creating e.g. the opportunity to recover and value low-grade operational heat sub-products. Such new and decentralized architecture, not currently applied in agroindustry, is proposed in this work. A chocolate tempering machine using an organic PCM is conceived and analyzed using ANSYS Fluent software for computational fluid dynamics simulations, comparing the main aspects in the storage capacity and discharging process with a conventional sensitive heat storage solution that uses water. PCMs allows improving the stored energy, keeping the chocolate in the working temperature after being tempered for more than four times longer than using only hot water. If the PCMs are charged by renewables, the self-consumption ratio can be improved while providing energy flexibility to the user.authorsversionpublishe

    The amplitude of mass fluctuations and mass density of the Universe constrained by strong gravitational lensing

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    We investigate the linear amplitude of mass fluctuations in the universe, σ8\sigma_8, and the present mass density parameter of the Universe, Ωm\Omega_\mathrm{m}, from the statistical strong gravitational lensing. We use the two populations of lens halos model with fixed cooling mass scale M_\mathrm{c}=3\times 10^{13}h^{-1}M_{\sun} to match the observed lensing probabilities, and leave σ8\sigma_8 or Ωm\Omega_\mathrm{m} as a free parameter to be constrained by data. Another varying parameter is the equation of state of dark energy ω\omega, and its typical values of -1, -2/3, -1/2 and -1/3 are investigated. We find that σ8\sigma_8 is degenerate with Ωm\Omega_\mathrm{m} in a way similar to that suggested by present day cluster abundance as well as cosmic shear lensing measurements: σ8Ωm0.60.33\sigma_8\Omega_\mathrm{m}^{0.6}\approx 0.33 (Bahcall & Bode\cite{bahcall03a} and references therein). However, both σ80.7\sigma_8\leq 0.7 and Ωm0.2\Omega_\mathrm{m}\leq 0.2 can be safely ruled out, the best value is when σ8=1.0\sigma_8=1.0, Ωm=0.3\Omega_\mathrm{m}=0.3 and ω=1\omega=-1. This result is different from that obtained by Bahcall & Bode (\cite{bahcall03a}), who gives σ8=0.98±0.1\sigma_8 =0.98\pm 0.1 and Ωm=0.17±0.05\Omega_m =0.17\pm 0.05. For σ8=1.0\sigma_8=1.0, higher value of Ωm=0.35\Omega_\mathrm{m}=0.35 requires ω=2/3\omega=-2/3 and Ωm=0.40\Omega_\mathrm{m}=0.40 requires ω=1/2\omega=-1/2.Comment: 9 pages, 4 figures, references update

    Quintessence with a constant equation of state in hyperbolic universes

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    Quintessence models leading to a constant equation of state are studied in hyperbolic universes. General properties of the quintessence potentials V(phi) are discussed, and for some special cases also the exact analytic expressions for these potentials are derived. It is shown that the observed angular power spectrum of the cosmic microwave background (CMB) is in excellent agreement with some of the quintessence models even in cases with negative curvature. It is emphasized that due to a (w_phi, Omega_phi, Omega_c)-degeneracy a universe with negative spatial curvature cannot be excluded.Comment: 15 pages, a version with figures in color can be obtained at http://www.physik.uni-ulm.de/theo/qc/ulm-tp/tp02-13.ps.g
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