961 research outputs found

    Nonlocality of the NN interaction in an effective field theory

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    We investigate low energy nucleon dynamics in the effective field theory (EFT) of nuclear forces. In leading order of the two-nucleon EFT we show that nucleon dynamics is governed by the generalized dynamical equation with a nonlocal-in-time interaction operator. This equation is shown to open new possibilities for applying the EFT approach to the description of low energy nucleon dynamics.Comment: 13 pages, 4 figures, REVTeX

    Progress in Absorber R&D for Muon Cooling

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    A stored-muon-beam neutrino factory may require transverse ionization cooling of the muon beam. We describe recent progress in research and development on energy absorbers for muon-beam cooling carried out by a collaboration of university and laboratory groups.Comment: 7 pages, 1 figure, presented at the 3rd International Workshop on Neutrino Factory Based on Muon Storage Rings (NuFACT'01), May 24-30, 2001, Tsukuba, Japa

    Depression and anxiety in sterilised women in Iran

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    Sterilisation is an effective and convenient means of contraception and has become increasingly popular as a birth control technique throughout the world during the past 40 years. However some women who choose sterilisation may suffer a neurotic syndrome, which is manifested in the form of pain, depression and loss of libido.1We undertook a study designed to investigate depression, anxiety and post-operation regret rate in sterilised women referred to health centres in Tabriz, Iran in 2006. The study design was descriptive-analytical. The study participants comprised 300 women in the age range 25–45 years, of whom 150 women were sterilized between 1 and 10 years ago and 150 were a control group of non-sterilised women who used condoms, withdrawal or safe period methods for contraception. The control group was selected by a cluster random sampling method. Fifteen health centres were selected as a cluster from 96 health centres located in Tabriz. Ten women were selected randomly from each health centre using health documents. Women were eligible for inclusion in the study if they were aged between 25 and 45 years at the time of sampling, and if they had no history of psychological disorders and no recent sorrowful events. There were no differences between the two groups as regards the number of children, income or demographic characteristics. The women were contacted by telephone at their last known address and were asked to complete questionnaires. Data collection was done using Zung’s self-rating depression and anxiety scale in addition to questions about post-sterilisation regret. Data were collected from the subjects anonymously and analysed using SPSS (v. 11.5) statistics software. Analysis employed t-test, Chi-square test and descriptive statistics. The comparison of the means for depression in the two groups was not significantly different (p = 0.96), however the mean of anxiety in the case group was remarkably greater than the control group (p = 0.03). Insufficient poststerilisation rest was a significant risk factor for depression and anxiety (p = 0.008 and p = 0.02, respectively). Requesting information about reversal after tubal sterilisation was 2.7% and the post-sterilisation regret rate was 6%, which was significantly related to women’s conflict with their husbands about the decision-making process prior to sterilisation (p<0.001). The study findings as regards psychological disorders of sterilisation suggested that women undergoing sterilisation should ensure that they have a good rest after their operation in order to reduce the extent of psychological disorders. Unlike studies undertaken in other countries,2–4 women’s age, parity, marriage duration and the timing of sterilisation was unrelated to the women’s regret in our study. The earlier the sterilisation is carried out, the longer the woman’s remaining period of fertile life and the greater the chances of changes in her marital status and/or the loss of a child, both circumstances that may lead to a change in the desired family size and expression of regret. In our study, probably one of the reasons why women’s regret did not appear to be significantly related to young age of sterilisation was the infrequency of divorce or remarriage in our study population. Consistent with our study, Jamieson et al. reported that women who had substantial conflict with their husbands or partners prior to sterilisation were more than three times as likely to regret their decision and more than five times more likely to request a reversal than women who did not report such conflict.5 In our study, pre-sterilisation counseling was reported by 29.3% of subjects. With respect to personality and adaptability differences in facing the changes, pre-sterilisation counseling and post-sterilisation follow-up systems have an important role to play in women’s psychological and psychosexual health promotion

    Studies of Neutron Stars at Optical/IR Wavelengths

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    In the last years, optical studies of Isolated Neutron Stars (INSs) have expanded from the more classical rotation-powered ones to other categories, like the Anomalous X-ray Pulsars (AXPs) and the Soft Gamma-ray Repeaters (SGRs), which make up the class of the magnetars, the radio-quiet INSs with X-ray thermal emission and, more recently, the enigmatic Compact Central Objects (CCOs) in supernova remnants. Apart from 10 rotation-powered pulsars, so far optical/IR counterparts have been found for 5 magnetars and for 4 INSs. In this work we present some of the latest observational results obtained from optical/IR observations of different types of INSs

    Lesbian and bisexual women's human rights, sexual rights and sexual citizenship: negotiating sexual health in England.

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    Lesbian and bisexual women's sexual health is neglected in much Government policy and practice in England and Wales. This paper examines lesbian and bisexual women's negotiation of sexual health, drawing on findings from a small research project. Themes explored include invisibility and lack of information, influences on decision-making and sexual activities and experiences of services and barriers to sexual healthcare. Key issues of importance in this respect are homophobic and heterosexist social contexts. Drawing on understandings of lesbian, gay and bisexual human rights, sexual rights and sexual citizenship, it is argued that these are useful lenses through which to examine and address lesbian and bisexual women's sexual health and related inequalities

    Clustering transitions in vibro-fluidized magnetized granular materials

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    We study the effects of long range interactions on the phases observed in cohesive granular materials. At high vibration amplitudes, a gas of magnetized particles is observed with velocity distributions similar to non-magnetized particles. Below a transition temperature compact clusters are observed to form and coexist with single particles. The cluster growth rate is consistent with a classical nucleation process. However, the temperature of the particles in the clusters is significantly lower than the surrounding gas, indicating a breakdown of equipartition. If the system is quenched to low temperatures, a meta-stable network of connected chains self-assemble due to the anisotropic nature of magnetic interactions between particles.Comment: 4 pages, 5 figure

    An observation of spin-valve effects in a semiconductor field effect transistor: a novel spintronic device

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    We present the first spintronic semiconductor field effect transistor. The injector and collector contacts of this device were made from magnetic permalloy thin films with different coercive fields so that they could be magnetized either parallel or antiparallel to each other in different applied magnetic fields. The conducting medium was a two dimensional electron gas (2DEG) formed in an AlSb/InAs quantum well. Data from this device suggest that its resistance is controlled by two different types of spin-valve effect: the first occurring at the ferromagnet-2DEG interfaces; and the second occuring in direct propagation between contacts.Comment: 4 pages, 2 figure

    Limitations of the heavy-baryon expansion as revealed by a pion-mass dispersion relation

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    The chiral expansion of nucleon properties such as mass, magnetic moment, and magnetic polarizability are investigated in the framework of chiral perturbation theory, with and without the heavy-baryon expansion. The analysis makes use of a pion-mass dispersion relation, which is shown to hold in both frameworks. The dispersion relation allows an ultraviolet cutoff to be implemented without compromising the symmetries. After renormalization, the leading-order heavy-baryon loops demonstrate a stronger dependence on the cutoff scale, which results in weakened convergence of the expansion. This conclusion is tested against the recent results of lattice quantum chromodynamics simulations for nucleon mass and isovector magnetic moment. In the case of the polarizability, the situation is even more dramatic as the heavy-baryon expansion is unable to reproduce large soft contributions to this quantity. Clearly, the heavy-baryon expansion is not suitable for every quantity.Comment: Accepted for publication in EPJ C. Made changes based on referee comments: clarifying sentences to conclusion 1. of Section IV, beginning of Section V, and new footnote in Section VI, page 8. Added more detailed explanation in paragraph 4 of Section III. Added citations of Phys.Rev. D60, 034014, and Phys.Lett. B716, 33

    Pulsar-wind nebulae and magnetar outflows: observations at radio, X-ray, and gamma-ray wavelengths

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    We review observations of several classes of neutron-star-powered outflows: pulsar-wind nebulae (PWNe) inside shell supernova remnants (SNRs), PWNe interacting directly with interstellar medium (ISM), and magnetar-powered outflows. We describe radio, X-ray, and gamma-ray observations of PWNe, focusing first on integrated spectral-energy distributions (SEDs) and global spectral properties. High-resolution X-ray imaging of PWNe shows a bewildering array of morphologies, with jets, trails, and other structures. Several of the 23 so far identified magnetars show evidence for continuous or sporadic emission of material, sometimes associated with giant flares, and a few possible "magnetar-wind nebulae" have been recently identified.Comment: 61 pages, 44 figures (reduced in quality for size reasons). Published in Space Science Reviews, "Jets and Winds in Pulsar Wind Nebulae, Gamma-ray Bursts and Blazars: Physics of Extreme Energy Release
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