1,613 research outputs found

    The QCD equation of state at finite T and mu

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    We calculate the pressure (p), the energy density (epsilon) and the baryon density (n(B)) of QCD at finite temperatures (T) and chemical potentials (mu). The recently proposed overlap improving multi-parameter reweighting technique is used to determine observables at nonvanishing chemical potentials. Our results are obtained by studying n(f) =2+1 dynamical staggered quarks with semi-realistic masses on N-t = 4 lattices

    Association of statin use in older people primary prevention group with risk of cardiovascular events and mortality: a systematic review and meta-analysis of observational studies

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    Background: Current evidence from randomized controlled trials on statins for primary prevention of cardiovascular disease (CVD) in older people, especially those aged > 75 years, is still lacking. We conducted a systematic review and meta-analysis of observational studies to extend the current evidence about the association of statin use in older people primary prevention group with risk of CVD and mortality. Methods: PubMed, Scopus, and Embase were searched from inception until March 18, 2021. We included observational studies (cohort or nested case-control) that compared statin use vs non-use for primary prevention of CVD in older people aged ≥ 65 years; provided that each of them reported the risk estimate on at least one of the following primary outcomes: all cause-mortality, CVD death, myocardial infarction (MI), and stroke. Risk estimates of each relevant outcome were pooled as a hazard ratio (HR) with a 95% confidence interval (CI) using the random-effects meta-analysis model. The quality of the evidence was rated using the GRADE approach. Results: Ten observational studies (9 cohorts and one case-control study; n = 815,667) fulfilled our criteria. The overall combined estimate suggested that statin therapy was associated with a significantly lower risk of all-cause mortality (HR: 0.86 [95% CI 0.79 to 0.93]), CVD death (HR: 0.80 [95% CI 0.78 to 0.81]), and stroke (HR: 0.85 [95% CI 0.76 to 0.94]) and a non-significant association with risk of MI (HR 0.74 [95% CI 0.53 to 1.02]). The beneficial association of statins with the risk of all-cause mortality remained significant even at higher ages (> 75 years old; HR 0.88 [95% CI 0.81 to 0.96]) and in both men (HR: 0.75 [95% CI: 0.74 to 0.76]) and women (HR 0.85 [95% CI 0.72 to 0.99]). However, this association with the risk of all-cause mortality remained significant only in those with diabetes mellitus (DM) (HR 0.82 [95% CI 0.68 to 0.98]) but not in those without DM. The level of evidence of all the primary outcomes was rated as "very low." Conclusions: Statin therapy in older people (aged ≥ 65 years) without CVD was associated with a 14%, 20%, and 15% lower risk of all-cause mortality, CVD death, and stroke, respectively. The beneficial association with the risk of all-cause mortality remained significant even at higher ages (> 75 years old), in both men and women, and in individuals with DM, but not in those without DM. These observational findings support the need for trials to test the benefits of statins in those above 75 years of age

    The Pioneer Anomaly

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    Radio-metric Doppler tracking data received from the Pioneer 10 and 11 spacecraft from heliocentric distances of 20-70 AU has consistently indicated the presence of a small, anomalous, blue-shifted frequency drift uniformly changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was interpreted as a constant sunward deceleration of each particular spacecraft at the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of the Newton's gravitational inverse-square law has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. In this review, we summarize the current knowledge of the physical properties of the anomaly and the conditions that led to its detection and characterization. We review various mechanisms proposed to explain the anomaly and discuss the current state of efforts to determine its nature. A comprehensive new investigation of the anomalous behavior of the two Pioneers has begun recently. The new efforts rely on the much-extended set of radio-metric Doppler data for both spacecraft in conjunction with the newly available complete record of their telemetry files and a large archive of original project documentation. As the new study is yet to report its findings, this review provides the necessary background for the new results to appear in the near future. In particular, we provide a significant amount of information on the design, operations and behavior of the two Pioneers during their entire missions, including descriptions of various data formats and techniques used for their navigation and radio-science data analysis. As most of this information was recovered relatively recently, it was not used in the previous studies of the Pioneer anomaly, but it is critical for the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living Reviews in Relativit

    Agronomic Management of Indigenous Mycorrhizas

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    Many of the advantages conferred to plants by arbuscular mycorrhiza (AM) are associated to the ability of AM plants to explore a greater volume of soil through the extraradical mycelium. Sieverding (1991) estimates that for each centimetre of colonized root there is an increase of 15 cm3 on the volume of soil explored, this value can increase to 200 cm3 depending on the circumstances. Due to the enhancement of the volume of soil explored and the ability of the extraradical mycelium to absorb and translocate nutrients to the plant, one of the most obvious and important advantages resulting from mycorrhization is the uptake of nutrients. Among of which the ones that have immobilized forms in soil, such as P, assume particular significance. Besides this, many other benefits are recognized for AM plants (Gupta et al, 2000): water stress alleviation (Augé, 2004; Cho et al, 2006), protection from root pathogens (Graham, 2001), tolerance to toxic heavy metals and phytoremediation (Audet and Charest, 2006; Göhre and Paszkowski, 2006), tolerance to adverse conditions such as very high or low temperature, high salinity (Sannazzaro et al, 2006), high or low pH (Yano and Takaki, 2005) or better performance during transplantation shock (Subhan et al, 1998). The extraradical hyphae also stabilize soil aggregates by both enmeshing soil particles (Miller e Jastrow, 1992) and producing a glycoprotein, golmalin, which may act as a glue-like substance to adhere soil particles together (Wright and Upadhyaya, 1998). Despite the ubiquous distribution of mycorrhizal fungi (Smith and Read, 2000) and only a relative specificity between host plants and fungal isolates (McGonigle and Fitter, 1990), the obligate nature of the symbiosis implies the establishment of a plant propagation system, either under greenhouse conditions or in vitro laboratory propagation. These techniques result in high inoculum production costs, which still remains a serious problem since they are not competitive with production costs of phosphorus fertilizer. Even if farmers understand the significance of sustainable agricultural systems, the reduction of phosphorus inputs by using AM fungal inocula alone cannot be justified except, perhaps, in the case of high value crops (Saioto and Marumoto, 2002). Nurseries, high income horticulture farmers and no-agricultural application such as rehabilitation of degraded or devegetated landscapes are examples of areas where the use of commercial inoculum is current. Another serious problem is quality of commercial available products concerning guarantee of phatogene free content, storage conditions, most effective application methods and what types to use. Besides the information provided by suppliers about its inoculum can be deceiving, as from the usually referred total counts, only a fraction may be effective for a particular plant or in specific soil conditions. Gianinazzi and Vosátka (2004) assume that progress should be made towards registration procedures that stimulate the development of the mycorrhizal industry. Some on-farm inoculum production and application methods have been studied, allowing farmers to produce locally adapted isolates and generate a taxonomically diverse inoculum (Mohandas et al, 2004; Douds et al, 2005). However the inocula produced this way are not readily processed for mechanical application to the fields, being an obstacle to the utilization in large scale agriculture, especially row crops, moreover it would represent an additional mechanical operation with the corresponding economic and soil compaction costs. It is well recognized that inoculation of AM fungi has a potential significance in not only sustainable crop production, but also environmental conservation. However, the status quo of inoculation is far from practical technology that can be widely used in the field. Together a further basic understanding of the biology and diversity of AM fungi is needed (Abbott at al, 1995; Saito and Marumoto, 2002). Advances in ecology during the past decade have led to a much more detailed understanding of the potential negative consequences of species introductions and the potential for negative ecological consequences of invasions by mycorrhizal fungi is poorly understood. Schwartz et al, (2006) recommend that a careful assessment documenting the need for inoculation, and the likelihood of success, should be conducted prior to inoculation because inoculations are not universally beneficial. Agricultural practices such as crop rotation, tillage, weed control and fertilizer apllication all produce changes in the chemical, physical and biological soil variables and affect the ecological niches available for occupancy by the soil biota, influencing in different ways the symbiosis performance and consequently the inoculum development, shaping changes and upset balance of native populations. The molecular biology tools developed in the latest years have been very important for our perception of these changes, ensuing awareness of management choice implications in AM development. In this context, for extensive farming systems and regarding environmental and economic costs, the identification of agronomic management practices that allow controlled manipulation of the fungal community and capitalization of AM mutualistic effect making use of local inoculum, seem to be a wise option for mycorrhiza promotion and development of sustainable crop production

    Search for C-parity violation in J/ψγγJ/ \psi \to \gamma\gamma and γϕ \gamma \phi

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    Using 1.06×1081.06\times10^8 ψ(3686)\psi(3686) events recorded in e+ee^{+}e^{-} collisions at s=\sqrt{s}= 3.686 GeV with the BESIII at the BEPCII collider, we present searches for C-parity violation in J/ψγγJ/\psi \to \gamma\gamma and γϕ \gamma \phi decays via ψ(3686)J/ψπ+π\psi(3686) \to J/\psi \pi^+\pi^-. No significant signals are observed in either channel. Upper limits on the branching fractions are set to be B(J/ψγγ)<2.7×107\mathcal{B}(J/\psi \to \gamma\gamma) < 2.7 \times 10^{-7} and B(J/ψγϕ)<1.4×106\mathcal{B}(J/\psi \to \gamma\phi) < 1.4 \times 10^{-6} at the 90\% confidence level. The former is one order of magnitude more stringent than the previous upper limit, and the latter represents the first limit on this decay channel.Comment: 7 pages, 2 figure

    Precision Measurement of the Mass of the τ\tau Lepton

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    An energy scan near the τ\tau pair production threshold has been performed using the BESIII detector. About 2424 pb1^{-1} of data, distributed over four scan points, was collected. This analysis is based on τ\tau pair decays to eeee, eμe\mu, eheh, μμ\mu\mu, μh\mu h, hhhh, eρe\rho, μρ\mu\rho and πρ\pi\rho final states, where hh denotes a charged π\pi or KK. The mass of the τ\tau lepton is measured from a maximum likelihood fit to the τ\tau pair production cross section data to be mτ=(1776.91±0.120.13+0.10m_{\tau} = (1776.91\pm0.12 ^{+0.10}_{-0.13}) MeV/c2c^2, which is currently the most precise value in a single measurement.Comment: 13 pages, 7 figure

    Search for the radiative transitions ψ(3770)γηc\psi(3770)\to\gamma\eta_c and γηc(2S)\gamma\eta_c(2S)

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    By using a 2.92 fb1^{-1} data sample taken at s=3.773\sqrt{s} = 3.773 GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions ψ(3770)γηc\psi(3770)\to\gamma\eta_c and γηc(2S)\gamma\eta_c(2S) through the hadronic decays ηc(ηc(2S))KS0K±π\eta_c(\eta_c(2S))\to K^0_SK^\pm\pi^\mp. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be B(ψ(3770)γηc)×B(ηcKS0K±π)<1.6×105\mathcal{B}(\psi(3770)\to\gamma\eta_c)\times \mathcal{B}(\eta_c\to K^0_SK^\pm\pi^\mp) < 1.6\times10^{-5} and B(ψ(3770)γηc(2S))×B(ηc(2S)KS0K±π)<5.6×106\mathcal{B}(\psi(3770)\to\gamma\eta_c(2S))\times \mathcal{B}(\eta_c(2S)\to K^0_SK^\pm\pi^\mp) < 5.6\times10^{-6}. Combining our result with world-average values of B(ηc(ηc(2S))KS0K±π)\mathcal{B}(\eta_c(\eta_c(2S))\to K^0_SK^\pm\pi^\mp), we find the branching fractions B(ψ(3770)γηc)<6.8×104\mathcal{B}(\psi(3770)\to\gamma\eta_c) < 6.8\times10^{-4} and B(ψ(3770)γηc(2S))<2.0×103\mathcal{B}(\psi(3770)\to\gamma\eta_c(2S)) < 2.0\times10^{-3} at a 90% confidence level.Comment: 10 pages, 4 figure

    Measurement of the proton form factor by studying e+eppˉe^{+} e^{-}\rightarrow p\bar{p}

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    Using data samples collected with the BESIII detector at the BEPCII collider, we measure the Born cross section of e+eppˉe^{+}e^{-}\rightarrow p\bar{p} at 12 center-of-mass energies from 2232.4 to 3671.0 MeV. The corresponding effective electromagnetic form factor of the proton is deduced under the assumption that the electric and magnetic form factors are equal (GE=GM)(|G_{E}|= |G_{M}|). In addition, the ratio of electric to magnetic form factors, GE/GM|G_{E}/G_{M}|, and GM|G_{M}| are extracted by fitting the polar angle distribution of the proton for the data samples with larger statistics, namely at s=\sqrt{s}= 2232.4 and 2400.0 MeV and a combined sample at s\sqrt{s} = 3050.0, 3060.0 and 3080.0 MeV, respectively. The measured cross sections are in agreement with recent results from BaBar, improving the overall uncertainty by about 30\%. The GE/GM|G_{E}/G_{M}| ratios are close to unity and consistent with BaBar results in the same q2q^{2} region, which indicates the data are consistent with the assumption that GE=GM|G_{E}|=|G_{M}| within uncertainties.Comment: 13 pages, 24 figure

    Observation of the ψ(13D2)\psi(1^3D_2) state in e+eπ+πγχc1e^+e^-\to\pi^+\pi^-\gamma\chi_{c1} at BESIII

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    We report the observation of the X(3823)X(3823) in the process e+eπ+πX(3823)π+πγχc1e^+e^-\to \pi^+\pi^-X(3823) \to \pi^+\pi^-\gamma\chi_{c1} with a statistical significance of 6.2σ6.2\sigma, in data samples at center-of-mass energies s=\sqrt{s}=4.230, 4.260, 4.360, 4.420 and 4.600~GeV collected with the BESIII detector at the BEPCII electron positron collider. The measured mass of the X(3823)X(3823) is (3821.7±1.3±0.7)(3821.7\pm 1.3\pm 0.7)~MeV/c2c^2, where the first error is statistical and the second systematic, and the width is less than 1616~MeV at the 90\% confidence level. The products of the Born cross sections for e+eπ+πX(3823)e^+e^-\to \pi^+\pi^-X(3823) and the branching ratio B[X(3823)γχc1,c2]\mathcal{B}[X(3823)\to \gamma\chi_{c1,c2}] are also measured. These measurements are in good agreement with the assignment of the X(3823)X(3823) as the ψ(13D2)\psi(1^3D_2) charmonium state.Comment: 7 pages, 3 figures, version to appear in Phys. Rev. Let
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