7,386 research outputs found

    On the origin of the various types of radio emission in GRS 1915+105

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    We investigate the association between the radio ``plateau'' states and the large superluminal flares in GRS 1915+105 and propose a qualitative scenario to explain this association. We identify several candidate superluminal flare events from available monitoring data on this source and analyze the contemporaneous RXTE pointed observations. We detect a strong correlation between the average X-ray flux during the ``plateau'' state and the total energy emitted in radio during the subsequent radio flare. We find that the sequence of events is similar for all large radio flares with a fast rise and exponential decay morphology. Based on these results, we propose a qualitative scenario in which the separating ejecta during the superluminal flares are observed due to the interaction of the matter blob ejected during the X-ray soft dips, with the steady jet already established during the ``plateau'' state. This picture can explain all types of radio emission observed from this source in terms of its X-ray emission characteristics.Comment: Corrected typo in the author names, contents unchanged, accepted in Ap

    Noise thermometry and electron thermometry of a sample-on-cantilever system below 1 Kelvin

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    We have used two types of thermometry to study thermal fluctuations in a microcantilever-based system below 1 K. We measured the temperature of a cantilever's macroscopic degree-of-freedom (via the Brownian motion of its lowest flexural mode) and its microscopic degrees-of-freedom (via the electron temperature of a metal sample mounted on the cantilever). We also measured both temperatures' response to a localized heat source. We find it possible to maintain thermal equilibrium between these two temperatures and a refrigerator down to at least 300 mK. These results are promising for ongoing experiments to probe quantum effects using micromechanical devices

    First determination of the CPCP content of Dπ+ππ+πD \to \pi^+\pi^-\pi^+\pi^- and updated determination of the CPCP contents of Dπ+ππ0D \to \pi^+\pi^-\pi^0 and DK+Kπ0D \to K^+K^-\pi^0

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    Quantum-correlated ψ(3770)DDˉ\psi(3770) \to D\bar{D} decays collected by the CLEO-c experiment are used to perform a first measurement of F+4πF_+^{4\pi}, the fractional CPCP-even content of the self-conjugate decay Dπ+ππ+πD \to \pi^+\pi^-\pi^+\pi^-, obtaining a value of 0.737±0.0280.737 \pm 0.028. An important input to the measurement comes from the use of DKS0π+πD \to K^0_{\rm S}\pi^+\pi^- and DKL0π+πD \to K^0_{\rm L}\pi^+\pi^- decays to tag the signal mode. This same technique is applied to the channels Dπ+ππ0D \to\pi^+\pi^-\pi^0 and DK+Kπ0D \to K^+K^-\pi^0, yielding F+πππ0=1.014±0.045±0.022F_+^{\pi\pi\pi^0} = 1.014 \pm 0.045 \pm 0.022 and F+KKπ0=0.734±0.106±0.054F_+^{KK\pi^0} = 0.734 \pm 0.106 \pm 0.054, where the first uncertainty is statistical and the second systematic. These measurements are consistent with those of an earlier analysis, based on CPCP-eigenstate tags, and can be combined to give values of F+πππ0=0.973±0.017F_+^{\pi\pi\pi^0} = 0.973 \pm 0.017 and F+KKπ0=0.732±0.055F_+^{KK\pi^0} = 0.732 \pm 0.055. The results will enable the three modes to be included in a model-independent manner in measurements of the unitarity triangle angle γ\gamma using BDKB^\mp \to DK^\mp decays, and in time-dependent studies of CPCP violation and mixing in the DDˉD\bar{D} system.Comment: Minor revisions following journal acceptanc

    Timing and spectral studies of the transient X-ray pulsar EXO 053109-6609.2 with ASCA and Beppo-SAX

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    We report timing and spectral properties of the transient Be X-ray pulsar EXO 053109--6609.2 studied using observations made with the ASCA and BeppoSAX observatories. Though there must have been at least one spin-down episode of the pulsar since its discovery, the new pulse period measurements show a monotonic spin-up trend since 1996. The pulse profile is found to have marginal energy dependence. There is also evidence for strong luminosity dependence of the pulse profile, a single peaked profile at low luminosity that changes to a double peaked profile at high luminosity. This suggests a change in the accretion pattern at certain luminosity level. The X-ray spectrum is found to consist of a simple power-law with photon index in the range of 0.4--0.8. At high intensity level the spectrum also shows presence of weak iron emission line.Comment: 12 pages, 8 figures, Accepted for publication in Ap

    Feshbach resonances in the 6Li-40K Fermi-Fermi mixture: Elastic versus inelastic interactions

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    We present a detailed theoretical and experimental study of Feshbach resonances in the 6Li-40K mixture. Particular attention is given to the inelastic scattering properties, which have not been considered before. As an important example, we thoroughly investigate both elastic and inelastic scattering properties of a resonance that occurs near 155 G. Our theoretical predictions based on a coupled channels calculation are found in excellent agreement with the experimental results. We also present theoretical results on the molecular state that underlies the 155G resonance, in particular concerning its lifetime against spontaneous dissociation. We then present a survey of resonances in the system, fully characterizing the corresponding elastic and inelastic scattering properties. This provides the essential information to identify optimum resonances for applications relying on interaction control in this Fermi-Fermi mixture.Comment: Submitted to EPJD, EuroQUAM special issues "Cold Quantum Matter - Achievements and Prospects", v2 with updated calibration of magnetic field (+4mG correction) and updated figures 4 and

    Liquid-like behaviour of gold nanowire bridges

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    A combination of Focused Ion Beam (FIB) and Reactive Ion Etch (RIE) was used to fabricate free standing gold nanowire bridges with radii of 30 nm and below. These were subjected to point loading to failure at their mid-points using an Atomic Force Microscope (AFM), providing strength and deformation data. The results demonstrate a dimensionally dependent transition from conventional solid metallic properties to liquid-like behaviour including the unexpected reformation of a fractured bridge. The work reveals mechanical and materials properties of nanowires which could have significant impact on nanofabrication processes and nanotechnology devices such as Nano Electro Mechanical Systems (NEMS)

    Maternal morbidity associated with violence and maltreatment from husbands and in-laws: findings from Indian slum communities.

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    BackgroundIntimate partner violence (IPV) victimization is linked to a broad range of negative maternal health outcomes. However, it is unclear whether IPV is directly related to poor maternal outcomes or whether IPV is a marker for other forms of chronic, mundane maltreatment of women that stem from the culture of gender inequity that also gives rise to IPV. To determine the prevalence of non-violent forms of gender-based household maltreatment by husbands and in-laws (GBHM), and violence from in-laws (ILV) and husbands (IPV) against women during the peripregnancy period (during and in the year prior to pregnancy); to assess relative associations of GBHM, ILV and IPV with maternal health.MethodsCross-sectional data were collected from women <6 months postpartum (n = 1,039, ages 15-35 years) seeking child immunization in Mumbai, India. Associations of IPV, ILV and GBHM during the peripregnancy period with maternal health (prenatal care in first trimester, no weight gain, pain during intercourse, high blood pressure, vaginal bleeding, premature rupture of membranes, premature birth) were evaluated.ResultsOne in three women (34.0 %) reported IPV, 4.8 % reported ILV, and 48.5 % reported GBHM during the peripregnancy period. After adjusting for other forms of abuse, IPV related to pain during intercourse (AOR = 1.79); ILV related to not receiving first trimester antenatal care (AOR = 0.49), and GBHM remained associated with premature rupture of membranes (AOR = 2.28), pain during intercourse (AOR = 1.60), and vaginal bleeding (AOR = 1.80).ConclusionAfter adjusting for ILV and IPV, peripregnancy GBHM remained significantly associated with multiple forms of maternal morbidity, suggesting that GBHM is a prevalent and reliable indicator of maternal health risk
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