834 research outputs found

    Stochastic Variational Search for ΛΛ4^{4}_{\Lambda\Lambda}H

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    A four-body calculation of the pnΛΛpn\Lambda\Lambda bound state, $^{\ 4}_{\Lambda\Lambda}H,isperformedusingthestochasticvariationalmethodandphenomenologicalpotentials.TheH, is performed using the stochastic variational method and phenomenological potentials. The NN,, \Lambda N,and, and \Lambda\LambdapotentialsaretakenfromarecentLetterbyFilikhinandGal,PRL89,172502(2002).AlthoughtheirFaddeev−Yakubovskycalculationfoundnobound−statesolutionoverawiderangeof potentials are taken from a recent Letter by Filikhin and Gal, PRL{\bf 89}, 172502 (2002). Although their Faddeev-Yakubovsky calculation found no bound-state solution over a wide range of \Lambda\Lambdainteractionstrengths,thepresentvariationalcalculationgivesabound−stateenergy,whichisclearlylowerthanthe interaction strengths, the present variational calculation gives a bound-state energy, which is clearly lower than the _\Lambda^3{H}+\Lambdathreshold,evenforaweak threshold, even for a weak \Lambda\Lambdainteractionstrengthdeducedfromarecentexperimental interaction strength deduced from a recent experimental B_{\Lambda\Lambda}(^{6}_{\Lambda\Lambda}{He})value.Thebindingenergiesobtainedarecloseto,andslightlylargerthan,thevaluesobtainedfromthethree−body value. The binding energies obtained are close to, and slightly larger than, the values obtained from the three-body d\Lambda\Lambda$ model in the Letter.Comment: Corrected typos, added addtional calculations regarding a truncated to l=0 interaction model, 4 pages, 3 figure

    ΛΛ\Lambda\Lambda-ΞN\Xi N-ΣΣ\Sigma\Sigma coupling in ΛΛ 6^{~6}_{\Lambda\Lambda}He with the Nijmegen soft-core potentials

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    The ΛΛ\Lambda\Lambda-ΞN\Xi N-ÎŁÎŁ\Sigma\Sigma coupling in ΛΛ 6^{~6}_{\Lambda\Lambda}He is studied with the [α\alpha + Λ\Lambda + Λ\Lambda] + [α\alpha + Ξ\Xi + NN] + [α\alpha + ÎŁ\Sigma + ÎŁ\Sigma] model, where the α\alpha particle is assumed as a frozen core. We use the Nijmegen soft-core potentials, NSC97e and NSC97f, for the valence baryon-baryon part, and the phenomenological potentials for the α−B\alpha-B parts (BB=NN, Λ\Lambda, Ξ\Xi and ÎŁ\Sigma). We find that the calculated ΔBΛΛ\Delta B_{\Lambda\Lambda} of ΛΛ 6^{~6}_{\Lambda\Lambda}He for NSC97e and NSC97f are, respectively, 0.6 and 0.4 MeV in the full coupled-channel calculation, the results of which are about half in comparison with the experimental data, ΔBΛΛexp=1.01±0.20−0.11+0.18\Delta B^{exp}_{\Lambda\Lambda}=1.01\pm0.20^{+0.18}_{-0.11} MeV. Characteristics of the S=−2S=-2 sector in the NSC97 potentials are discussed in detail.Comment: 18 pages, 4 figure

    Does \Sigma -\Sigma -\alpha Form a Quasi-Bound State?

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    We have investigated the possible existence of a quasi-bound state for the \Sigma -\Sigma -\alpha system in the framework of Faddeev calculations. We are particularly interested in the state of total iso-spin T=2, since for an inert \alpha particle there is no strong conversion to \Xi -N-\alpha or \Lambda -\Lambda -\alpha possible. A \Sigma -\alpha optical potential based on Nijmegen model D and original \Sigma -\Sigma interactions of the series of Nijmegen potentials NSC97 as well a simulated Gaussian type versions thereof are used. Our investigation of the \Sigma -\Sigma -\alpha system leads to a quasi bound state where, depending on the potential parameters, the energy ranges between -1.4 and -2.4 MeV and the level width is about 0.2MeV.Comment: 13 pages, 4 figures, 5 table

    Vagus Nerve Stimulation in Refractory Epilepsy: Effects on Pro- and Anti-Inflammatory Cytokines in Peripheral Blood

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    Objective: The vagus nerve has important immunological functions that may be relevant for its anticonvulsive action. We postulate that this anticonvulsive action is activated by a shift in the immune system resulting in a reduction of neurotoxic and an increase of neuroprotective tryptophan metabolites. Methods: Eleven patients with refractory epilepsy and 11 controls matched for age and gender were included in this study. The primary outcome measure was a 50% seizure reduction. Other variables were pro-inflammatory cytokines IL-6 and TNF-alpha, anti-inflammatory cytokine IL-10, cortisol, and the tryptophan metabolites 3-hydroxykynurenine (3-OH-KYN), kynurenic acid (KYNA), kynurenine, serotonin (5-HT) and 5-hydroxyindol acetic acid (5-HIAA). Blood samples were scheduled during baseline, and in week 28 of add-on treatment. Results: IL-6 levels were higher in the responders than in the control group, and decreased after vagus nerve stimulation (VNS), whereas IL-10 was low and increased after VNS. In nonresponders, VNS resulted in an increase of IL-6 plasma levels and in a decrease of IL-10. Cortisol concentrations are higher in the epilepsy group than in the control group. After VNS, these concentrations decreased. The concentrations of the tryptophan metabolites were lower in the epilepsy group than in the control group. The KYNA ratios are defined as the ratio of neuroprotective KYNA versus neurotoxic 3-OH-KYN and KYNA versus neurotoxic kynurenine: these ratios were lower in epilepsy patients than in controls, and they both moderately increased after VNS. Conclusion: The outcome of this preliminary study indicates that VNS causes a rebalancing of the immune system. This results in: (1) a reduction of neurotoxic and an increase of neuroprotective kynurenine metabolites and (2) in the normalization of cortisol levels. Copyright (C) 2010 S. Karger AG, Base

    A systematic review of tranexamic acid in hip fracture surgery

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    Aim: To systematically examine and quantify the efficacy and safety of Tranexamic acid in hip fracture surgery.  Methods: A systematic literature search was conducted using Medline, EMBASE, AMED, CiNAHL, and the Cochrane Central Registry of Controlled Trials. Two assessors independently screened search outputs for potentially relevant articles which met the eligibility criteria. The primary outcome measure was requirement of post-operative blood transfusion. Risk of bias assessment was performed using the Cochrane Collaboration’s risk of bias tool for RCT’s and the ROBINS-I tool for observational studies. Meta-analysis was performed to estimate risk ratio (RR), risk difference (RD) and mean difference (MD) values for dichotomous and continuous data outcomes respectively. The interpretation of each outcome was made using the GRADE approach.  Results: Of 102 studies identified, seven met the inclusion criteria including a total of 770 participants (TXA: 341; Control: 429). On meta-analysis, intra-venous TXA resulted in a 46% risk reduction in blood transfusion requirement compared to a placebo/control group (RR:0.54; 95% CI: 0.35 to 0.85; I2: 78%; Inconsistency (Chi2) p=<0.0001; N=750). There was also a significantly higher post-operative haemoglobin for TXA versus placebo/control (MD:0.81; 95% CI: 0.45 to 1.18; I2: 46%; Inconsistency (Chi2) p=0.10; N=638). There was no increased risk of thromboembolic events (RD:0.01; 95% CI: -0.03, 0.05; I2: 68%; Inconsistency (Chi2) p=0.007, N=683).  Conclusion: There is moderate quality evidence that TXA reduces blood transfusion in hip fracture surgery, with low quality evidence suggesting no increased risk of thrombotic events. These findings are consistent with TXA use in other orthopaedic procedures

    Hyperonic mixing in five-baryon double-strangeness hypernuclei in a two-channel treatment

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    Properties of hypernuclei ΛΛ5_{\Lambda \Lambda}^5H and ΛΛ5_{\Lambda \Lambda }^5He are studied in a two-channel approach with explicit treatment of coupling of channels ^3\text{Z}+\Lambda+\Lambda and \alpha+\Xi. Diagonal \Lambda\Lambda and coupling \Lambda\Lambda-\Xi N interactions are derived within G-matrix procedure from Nijmegen meson-exchange models. Bond energy \Delta B_{\Lambda\Lambda} in ΛΛ5_{\Lambda \Lambda}^5He exceeds significantly that in ΛΛ5_{\Lambda \Lambda}^5H due to the channel coupling. Diagonal \Xi\alpha attraction amplifies the effect, which is sensitive also to \Lambda-core interaction. The difference of the \Delta B_{\Lambda\Lambda} values can be an unambiguous signature of the \Lambda\Lambda-\Xi N coupling in \Lambda\Lambda hypernuclei. However, improved knowledge of the hyperon-nucleus potentials is needed for quantitative extraction of the coupling strength from future data on the \Lambda\Lambda hypernuclear binding energies.Comment: 11 pages with 3 figures; Phys. Rev. C, accepte

    Impact of HIV on inpatient mortality and complications in stroke in Thailand: a National Database Study.

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    The co-existence of stroke and HIV has increased in recent years, but the impact of HIV on post-stroke outcomes is poorly understood. We examined the impact of HIV on inpatient mortality, length of acute hospital stay and complications (pneumonia, respiratory failure, sepsis and convulsions), in hospitalized strokes in Thailand. All hospitalized strokes between 1 October 2004 and 31 January 2013 were included. Data were obtained from a National Insurance Database. Characteristics and outcomes for non-HIV and HIV patients were compared and multivariate logistic and linear regression models were constructed to assess the above outcomes. Of 610 688 patients (mean age 63·4 years, 45·4% female), 0·14% (866) had HIV infection. HIV patients were younger, a higher proportion were male and had higher prevalence of anaemia (P < 0·001) compared to non-HIV patients. Traditional cardiovascular risk factors, hypertension and diabetes, were more common in the non-HIV group (P < 0·001). After adjusting for age, sex, stroke type and co-morbidities, HIV infection was significantly associated with higher odds of sepsis [odds ratio (OR) 1·75, 95% confidence interval (CI) 1·29-2·4], and inpatient mortality (OR 2·15, 95% CI 1·8-2·56) compared to patients without HIV infection. The latter did not attenuate after controlling for complications (OR 2·20, 95% CI 1·83-2·64). HIV infection is associated with increased odds of sepsis and inpatient mortality after acute stroke
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