1,126 research outputs found

    Young neutron stars with soft gamma ray emission and anomalous X-ray pulsar

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    The observational properties of Soft Gamma Repeaters and Ano\-malous X-ray Pulsars (SGR/AXP) indicate to necessity of the energy source different from a rotational energy of a neutron star. The model, where the source of the energy is connected with a magnetic field dissipation in a highly magnetized neutron star (magnetar) is analyzed. Some observational inconsistencies are indicated for this interpretation. The alternative energy source, connected with the nuclear energy of superheavy nuclei stored in the nonequilibrium layer of low mass neutron star is discussed.Comment: 29 pages, 13 figures, Springer International Publishing Switzerland 2016 A.W. Alsabti, P. Murdin (eds.), Handbook of Supernova

    On the stability of high-speed milling with spindle speed variation

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    Spindle speed variation is a well-known technique to suppress regenerative machine tool vibrations, but it is usually considered to be effective only for low spindle speeds. In this paper, the effect of spindle speed variation is analyzed in the high-speed domain for spindle speeds corresponding to the first flip (period doubling) and to the first Hopf lobes. The optimal amplitudes and frequencies of the speed modulations are computed using the semidiscre- tization method. It is shown that period doubling chatter can effectively be suppressed by spindle speed variation, although, the technique is not effective for the quasiperiodic chatter above the Hopf lobe. The results are verified by cutting tests. Some special cases are also discussed where the practical behavior of the system differs from the predicted one in some ways. For these cases, it is pointed out that the concept of stability is understood on the scale of the principal period of the system—that is, the speed modulation period for variable spindle speed machining and the tooth passing period for constant spindle speed machining

    Voluntary exercise can strengthen the circadian system in aged mice

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    Consistent daily rhythms are important to healthy aging according to studies linking disrupted circadian rhythms with negative health impacts. We studied the effects of age and exercise on baseline circadian rhythms and on the circadian system's ability to respond to the perturbation induced by an 8 h advance of the light:dark (LD) cycle as a test of the system's robustness. Mice (male, mPer2luc/C57BL/6) were studied at one of two ages: 3.5 months (n = 39) and >18 months (n = 72). We examined activity records of these mice under entrained and shifted conditions as well as mPER2::LUC measures ex vivo to assess circadian function in the suprachiasmatic nuclei (SCN) and important target organs. Age was associated with reduced running wheel use, fragmentation of activity, and slowed resetting in both behavioral and molecular measures. Furthermore, we observed that for aged mice, the presence of a running wheel altered the amplitude of the spontaneous firing rate rhythm in the SCN in vitro. Following a shift of the LD cycle, both young and aged mice showed a change in rhythmicity properties of the mPER2::LUC oscillation of the SCN in vitro, and aged mice exhibited longer lasting internal desynchrony. Access to a running wheel alleviated some age-related changes in the circadian system. In an additional experiment, we replicated the effect of the running wheel, comparing behavioral and in vitro results from aged mice housed with or without a running wheel (>21 months, n = 8 per group, all examined 4 days after the shift). The impact of voluntary exercise on circadian rhythm properties in an aged animal is a novel finding and has implications for the health of older people living with environmentally induced circadian disruption

    International Veterinary Epilepsy Task Force recommendations for a veterinary epilepsy-specific MRI protocol

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    Epilepsy is one of the most common chronic neurological diseases in veterinary practice. Magnetic resonance imaging (MRI) is regarded as an important diagnostic test to reach the diagnosis of idiopathic epilepsy. However, given that the diagnosis requires the exclusion of other differentials for seizures, the parameters for MRI examination should allow the detection of subtle lesions which may not be obvious with existing techniques. In addition, there are several differentials for idiopathic epilepsy in humans, for example some focal cortical dysplasias, which may only apparent with special sequences, imaging planes and/or particular techniques used in performing the MRI scan. As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature. There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. A 6–7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed

    The use of biomedicine, complementary and alternative medicine, and ethno-medicine for the treatment of epilepsy among people of South Asian origin in the UK

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    Studies have shown that a significant proportion of people with epilepsy use complementary and alternative medicine (CAM). CAM use is known to vary between different ethnic groups and cultural contexts; however, little attention has been devoted to inter-ethnic differences within the UK population. We studied the use of biomedicine, complementary and alternative medicine, and ethnomedicine in a sample of people with epilepsy of South Asian origin living in the north of England

    Chiral perturbation theory in a magnetic background - finite-temperature effects

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    We consider chiral perturbation theory for SU(2) at finite temperature TT in a constant magnetic background BB. We compute the thermal mass of the pions and the pion decay constant to leading order in chiral perturbation theory in the presence of the magnetic field. The magnetic field gives rise to a splitting between Mπ0M_{\pi^0} and Mπ±M_{\pi^{\pm}} as well as between Fπ0F_{\pi^0} and Fπ±F_{\pi^{\pm}}. We also calculate the free energy and the quark condensate to next-to-leading order in chiral perturbation theory. Both the pion decay constants and the quark condensate are decreasing slower as a function of temperature as compared to the case with vanishing magnetic field. The latter result suggests that the critical temperature TcT_c for the chiral transition is larger in the presence of a constant magnetic field. The increase of TcT_c as a function of BB is in agreement with most model calculations but in disagreement with recent lattice calculations.Comment: 24 pages and 9 fig

    Exact Results and Holography of Wilson Loops in N=2 Superconformal (Quiver) Gauge Theories

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    Using localization, matrix model and saddle-point techniques, we determine exact behavior of circular Wilson loop in N=2 superconformal (quiver) gauge theories. Focusing at planar and large `t Hooft couling limits, we compare its asymptotic behavior with well-known exponential growth of Wilson loop in N=4 super Yang-Mills theory. For theory with gauge group SU(N) coupled to 2N fundamental hypermultiplets, we find that Wilson loop exhibits non-exponential growth -- at most, it can grow a power of `t Hooft coupling. For theory with gauge group SU(N) x SU(N) and bifundamental hypermultiplets, there are two Wilson loops associated with two gauge groups. We find Wilson loop in untwisted sector grows exponentially large as in N=4 super Yang-Mills theory. We then find Wilson loop in twisted sector exhibits non-analytic behavior with respect to difference of two `t Hooft coupling constants. By letting one gauge coupling constant hierarchically larger/smaller than the other, we show that Wilson loops in the second type theory interpolate to Wilson loop in the first type theory. We infer implications of these findings from holographic dual description in terms of minimal surface of dual string worldsheet. We suggest intuitive interpretation that in both type theories holographic dual background must involve string scale geometry even at planar and large `t Hooft coupling limit and that new results found in the gauge theory side are attributable to worldsheet instantons and infinite resummation therein. Our interpretation also indicate that holographic dual of these gauge theories is provided by certain non-critical string theories.Comment: 52 pages, 7 figures v2. more figures embedded v3. minor stylistic changes, v4. published versio

    Facilitative parenting and children's social, emotional and behavioural adjustment

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    Facilitative parenting (FP) supports the development of children’s social and emotional competence and effective peer relationships. Previous research has shown that FP discriminates between children bullied by peers from children who are not bullied, according to reports of teachers. This study investigates the association between FP and children’s social, emotional and behavioral problems, over and above the association with dysfunctional parenting (DP). 215 parents of children aged 5–11 years completed questionnaires about parenting and child behavior, and children and teachers completed measures of child bullying victimization. As predicted, FP accounted for variance in teacher reports of children’s bullying victimization as well as parent reports of children’s social and emotional problems and prosocial behavior better than that accounted for by DP. However for children’s reports of peer victimization the whole-scale DP was a better predictor than FP. Contrary to predictions, FP accounted for variance in conduct problems and hyperactivity better than DP. When analyses were replicated substituting subscales of dysfunctional and FP, a sub-set of FP subscales including Warmth, Supports Friendships, Not Conflicting, Child Communicates and Coaches were correlated with low levels of problems on a broad range of children’s adjustment problems. Parent–child conflict accounted for unique variance in children’s peer victimization (teacher report), peer problems, depression, emotional problems, conduct problems and hyperactivity. The potential relevance of FP as a protective factor for children against a wide range of adjustment problems is discussed

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Comparison of the efficacy of a neutral wrist splint and wrist splint with lumbrical unit for the treatment of patients with carpal tunnel syndrome

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    Purpose: The purpose of this study was to compare the effect of a neutral wrist splint or a wrist splint with an additional metacarpophalangeal (MCP) unit on pain, function, grip and pinch strength in patients with mild-to-moderate carpal tunnel syndrome (CTS). Methods: Twenty four patients received conservative treatment using either the neutral wrist splint or wrist splint with the MCP unit for a period of 6 weeks. Primary outcome measures were pain, function, grip and pinch strength. Data was collected immediately before and after using the two types of splints at baseline (0 weeks) and 6 weeks. Statistical analysis was performed using the paired t-test and independent T-test. Results: Compared to baseline, both the neutral wrist splint and the wrist splint with an MCP unit significantly decreased pain, increased function and pinch and grip strength. Comparisons of the two types of splints for grip (P =0.675) and pinch strength (P =0.650) revealed that there were no significant differences between the two after 6 weeks of wear. However, there were significant differences in pain levels (P =0.022) and the DASH score (P =0.027) between the two types of splints from baseline to 6 weeks. Conclusion: The wrist splint with an MCP unit was more effective than the neutral wrist splint in pain reduction and improvement of function
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