1,228 research outputs found

    Numerical loop quantum cosmology: an overview

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    A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key prediction of the bounce at the Planck scale in different models, and the numerical methods used to analyze the properties of the quantum difference operator and the von Neumann stability issues. Using the quantization of a massless scalar field in an isotropic spacetime as a template, an attempt is made to highlight the complementarity of different methods to gain understanding of the new physics emerging from the quantum theory. Open directions which need to be explored with more refined numerical methods are discussed.Comment: 33 Pages, 4 figures. Invited contribution to appear in Classical and Quantum Gravity special issue on Non-Astrophysical Numerical Relativit

    Loop Quantum Cosmology: A Status Report

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    The goal of this article is to provide an overview of the current state of the art in loop quantum cosmology for three sets of audiences: young researchers interested in entering this area; the quantum gravity community in general; and, cosmologists who wish to apply loop quantum cosmology to probe modifications in the standard paradigm of the early universe. An effort has been made to streamline the material so that, as described at the end of section I, each of these communities can read only the sections they are most interested in, without a loss of continuity.Comment: 138 pages, 15 figures. Invited Topical Review, To appear in Classical and Quantum Gravity. Typos corrected, clarifications and references adde

    Compulsory admission at first presentation to services for psychosis: does ethnicity still matter? Findings from two population-based studies of first episode psychosis

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    Objectives Compared with the majority population, those from minority ethnic groups in the UK are more likely to be admitted compulsorily during a first episode of psychosis (FEP). We investigated whether these disparities in pathways in to care continue. Methods We analysed data from two first episode psychosis studies, conducted in the same geographical area in south London 15 years apart: the Aetiology and Ethnicity in Schizophrenia and Other Psychosis (AESOP) and the Clinical Record Interactive Search-First Episode Psychosis (CRIS-FEP) studies. The inclusion/exclusion criteria for case ascertainment for first episode psychosis were identical across the two studies. We performed multivariable logistic regression to estimate odds of compulsory admission by ethnic group, controlling for confounders. Participants Two hundred sixty-six patients with first episode psychosis, aged 18–64 years, who presented to mental health services in south London in 1997–1999 and 446 with FEP who presented in 2010–2012. Results When the two samples were compared, ethnic differences in compulsory admission appear to have remained the same for black African patients, i.e. three times higher than white British in both samples: AESOP (adj. OR = 3.96; 95% CI = 1.80–8.71) vs. CRIS-FEP (adj. OR = 3.12; 95% CI = 1.52–6.35). Black Caribbean patients were three times more likely to be compulsorily admitted in AESOP (adj. OR = 3.20; 95% CI = 1.56–6.54). This was lower in the CRIS-FEP sample (adj. OR = 1.68; 95% CI = 0.71–3.98) and did not meet conventional levels for statistical significance. Conclusion Ethnicity is strongly associated with compulsory admissions at first presentation for psychosis with evidence of heterogeneity across groups, which deserves further research

    A frequentist framework of inductive reasoning

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    Reacting against the limitation of statistics to decision procedures, R. A. Fisher proposed for inductive reasoning the use of the fiducial distribution, a parameter-space distribution of epistemological probability transferred directly from limiting relative frequencies rather than computed according to the Bayes update rule. The proposal is developed as follows using the confidence measure of a scalar parameter of interest. (With the restriction to one-dimensional parameter space, a confidence measure is essentially a fiducial probability distribution free of complications involving ancillary statistics.) A betting game establishes a sense in which confidence measures are the only reliable inferential probability distributions. The equality between the probabilities encoded in a confidence measure and the coverage rates of the corresponding confidence intervals ensures that the measure's rule for assigning confidence levels to hypotheses is uniquely minimax in the game. Although a confidence measure can be computed without any prior distribution, previous knowledge can be incorporated into confidence-based reasoning. To adjust a p-value or confidence interval for prior information, the confidence measure from the observed data can be combined with one or more independent confidence measures representing previous agent opinion. (The former confidence measure may correspond to a posterior distribution with frequentist matching of coverage probabilities.) The representation of subjective knowledge in terms of confidence measures rather than prior probability distributions preserves approximate frequentist validity.Comment: major revisio

    Oral rehydration versus intravenous therapy for treating dehydration due to gastroenteritis in children: a meta-analysis of randomised controlled trials

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    BACKGROUND: Despite treatment recommendations from various organizations, oral rehydration therapy (ORT) continues to be underused, particularly by physicians in high-income countries. We conducted a systematic review of randomised controlled trials (RCTs) to compare ORT and intravenous therapy (IVT) for the treatment of dehydration secondary to acute gastroenteritis in children. METHODS: RCTs were identified through MEDLINE, EMBASE, CENTRAL, authors and references of included trials, pharmaceutical companies, and relevant organizations. Screening and inclusion were performed independently by two reviewers in order to identify randomised or quasi-randomised controlled trials comparing ORT and IVT in children with acute diarrhea and dehydration. Two reviewers independently assessed study quality using the Jadad scale and allocation concealment. Data were extracted by one reviewer and checked by a second. The primary outcome measure was failure of rehydration. We analyzed data using standard meta-analytic techniques. RESULTS: The quality of the 14 included trials ranged from 0 to 3 (Jadad score); allocation concealment was unclear in all but one study. Using a random effects model, there was no significant difference in treatment failures (risk difference [RD] 3%; 95% confidence intervals [CI]: 0, 6). The Mantel-Haenzsel fixed effects model gave a significant difference between treatment groups (RD 4%; 95% CI: 2, 5) favoring IVT. Based on the four studies that reported deaths, there were six in the IVT groups and two in ORT. There were no significant differences in total fluid intake at six and 24 hours, weight gain, duration of diarrhea, or hypo/hypernatremia. Length of stay was significantly shorter for the ORT group (weighted mean difference [WMD] -1.2 days; 95% CI: -2.4,-0.02). Phlebitis occurred significantly more often with IVT (number needed to treat [NNT] 33; 95% CI: 25,100); paralytic ileus occurred more often with ORT (NNT 33; 95% CI: 20,100). These results may not be generalizable to children with persistent vomiting. CONCLUSION: There were no clinically important differences between ORT and IVT in terms of efficacy and safety. For every 25 children (95% CI: 20, 50) treated with ORT, one would fail and require IVT. The results support existing practice guidelines recommending ORT as the first course of treatment in appropriate children with dehydration secondary to gastroenteritis

    Immunosuppressive treatment for proliferative lupus nephritis

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    Background Cyclophosphamide, in combination with corticosteroids, has been first-line treatment for inducing disease remission for proliferative lupus nephritis, reducing death at five years from over 50% in the 1950s and 1960s to less than 10% in recent years. Several treatment strategies designed to improve remission rates and minimise toxicity have become available. Treatments, including mycophenolate mofetil (MMF) and calcineurin inhibitors, alone and in combination, may have equivalent or improved rates of remission, lower toxicity (less alopecia and ovarian failure) and uncertain effects on death, end-stage kidney disease (ESKD) and infection. This is an update of a Cochrane review first published in 2004 and updated in 2012. Objectives Our objective was to assess the evidence and evaluate the benefits and harms of different immunosuppressive treatments in people with biopsy-proven lupus nephritis. The following questions relating to management of proliferative lupus nephritis were addressed: 1) Are new immunosuppressive agents superior to or as effective as cyclophosphamide plus corticosteroids? 2) Which agents, dosages, routes of administration and duration of therapy should be used? 3) Which toxicities occur with the different treatment regimens? Search methods We searched the Cochrane Kidney and Transplant Specialised Register up to 2 March 2018 with support from the Cochrane Information Specialist using search terms relevant to this review. Studies in the Specialised Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. Selection criteria Randomised controlled trials (RCTs) and quasi-RCTs comparing any immunosuppressive treatment for biopsy-proven class III, IV, V+III and V+VI lupus nephritis in adult or paediatric patients were included. Data collection and analysis Data were abstracted and the risks of bias were assessed independently by two authors. Dichotomous outcomes were calculated as risk ratio (RR) and measures on continuous scales calculated as mean differences (MD) with 95% confidence intervals (CI). The primary outcomes were death (all causes) and complete disease remission for induction therapy and disease relapse for maintenance therapy. Evidence certainty was determined using GRADE. Main results In this review update, 26 new studies were identified, to include 74 studies involving 5175 participants overall. Twenty-nine studies included children under the age of 18 years with lupus nephritis, however only two studies exclusively examined the treatment of lupus nephritis in patients less than 18 years of age. Induction therapy Sixty-seven studies (4791 participants; median 12 months duration (range 2.5 to 48 months)) reported induction therapy. The effects of all treatment strategies on death (all causes) and ESKD were uncertain (very low certainty evidence) as this outcome occurred very infrequently. Compared with intravenous (IV) cyclophosphamide, MMF may have increased complete disease remission (RR 1.17, 95% CI 0.97 to 1.42; low certainty evidence), although the range of effects includes the possibility of little or no difference. Compared to IV cyclophosphamide, MMF is probably associated with decreased alopecia (RR 0.29, 95% CI 0.19 to 0.46; 170 less (129 less to 194 less) per 1000 people) (moderate certainty evidence), increased diarrhoea (RR 2.42, 95% CI 1.64 to 3.58; 142 more (64 more to 257 more) per 1000 people) (moderate certainty evidence) and may have made little or no difference to major infection (RR 1.02, 95% CI 0.67 to 1.54; 2 less (38 less to 62 more) per 1000 people) (low certainty evidence). It is uncertain ifMMF decreased ovarian failure compared to IV cyclophosphamide because the certainty of the evidence was very low (RR 0.36, 95% CI 0.06 to 2.18; 26 less (39 less to 49 more) per 1000 people). Studies were not generally designed to measure ESKD. MMF combined with tacrolimus may have increased complete disease remission (RR 2.38, 95% CI 1.07 to 5.30; 336 more (17 to 1048 more) per 1000 people (low certainty evidence) compared with IV cyclophosphamide, however the effects on alopecia, diarrhoea, ovarian failure, and major infection remain uncertain. Compared to standard of care, the effects of biologics on most outcomes were uncertain because of low to very low certainty of evidence. Maintenance therapy Nine studies (767 participants; median 30 months duration (range 6 to 63 months)) reported maintenance therapy. In maintenance therapy, disease relapse is probably increased with azathioprine compared with MMF (RR 1.75, 95% CI 1.20 to 2.55; 114 more (30 to 236 more) per 1000 people (moderate certainty evidence).Multiple other interventions were compared as maintenance therapy, but patient-outcome data were sparse leading to imprecise estimates. Authors’ conclusions In this review update, studies assessing treatment for proliferative lupus nephritis were not designed to assess death (all causes) or ESKD. MMF may lead to increased complete disease remission compared with IV cyclophosphamide, with an acceptable adverse event profile, although evidence certainty was low and included the possibility of no difference. Calcineurin combined with lower dose MMF may improve induction of disease remission compared with IV cyclophosphamide, but the comparative safety profile of these therapies is uncertain. Azathioprine may increase disease relapse as maintenance therapy compared with MMF.Internal support - Cochrane Kidney and Transplant, Australia. External support - Cochrane Review Support Programme 2017, UK

    Improving the biopharmaceutical attributes of mangiferin using vitamin E-TPGS co-loaded self-assembled phosholipidic nano-mixed micellar systems

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    The current research work encompasses the development, characterization, and evaluation of self-assembled phospholipidic nano-mixed miceller system (SPNMS) of a poorly soluble BCS Class IV xanthone bioactive, mangiferin (Mgf) functionalized with co-delivery of vitamin E TPGS. Systematic optimization using I-optimal design yielded self-assembled phospholipidic nano-micelles with a particle size of  80% of drug release in 15 min. The cytotoxicity and cellular uptake studies performed using MCF-7 and MDA-MB-231 cell lines demonstrated greater kill and faster cellular uptake. The ex vivo intestinal permeability revealed higher lymphatic uptake, while in situ perfusion and in vivo pharmacokinetic studies indicated nearly 6.6- and 3.0-folds augmentation in permeability and bioavailability of Mgf. In a nutshell, vitamin E functionalized SPNMS of Mgf improved the biopharmaceutical performance of Mgf in rats for enhanced anticancer potency

    Impaired Mitochondrial Microbicidal Responses in Chronic Obstructive Pulmonary Disease Macrophages

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    RATIONALE: Chronic obstructive pulmonary disease (COPD) is characterized by impaired clearance of pulmonary bacteria. OBJECTIVES: The effect of COPD on alveolar macrophage (AM) microbicidal responses was investigated. METHODS: Alveolar macrophages (AMs) were obtained from bronchoalveolar lavage from healthy donors or COPD patients and challenged with opsonized serotype 14 Streptococcus pneumoniae. Cells were assessed for apoptosis, bactericidal activity and mitochondrial reactive oxygen species (mROS) production. A transgenic mouse line, in which the CD68 promoter ensures macrophage specific expression of human Mcl-1 (CD68.hMcl-1), was used to model the molecular aspects of COPD. MEASUREMENTS AND MAIN RESULTS: COPD AM had elevated levels of Mcl-1, an anti-apoptotic Bcl-2 family member, with selective reduction of delayed intracellular bacterial killing. CD68.hMcl-1 AM phenocopied the microbicidal defect since transgenic mice demonstrated impaired clearance of pulmonary bacteria and increased neutrophilic inflammation. Murine bone marrow-derived macrophages (BMDM) and human monocyte-derived macrophages (MDM) generated mitochondrial reactive oxygen species (mROS) in response to pneumococci, which co-localized with bacteria and phagolysosomes to enhance bacterial killing. The Mcl-1 transgene increased oxygen consumption rates and mROS expression in mock-infected BMDM but reduced caspase-dependent mROS production after pneumococcal challenge. COPD AM also increased basal mROS expression, but failed to increase production after pneumococcal challenge, in keeping with reduced intracellular bacterial killing. The defect in COPD AM intracellular killing was associated with a reduced ratio of mROS /superoxide dismutase 2. CONCLUSIONS: Upregulation of Mcl-1 and chronic adaption to oxidative stress alters mitochondrial metabolism and microbicidal function, reducing the delayed phase of intracellular bacterial clearance in COPD

    Hsp90 orchestrates transcriptional regulation by Hsf1 and cell wall remodelling by MAPK signalling during thermal adaptation in a pathogenic yeast

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    Acknowledgments We thank Rebecca Shapiro for creating CaLC1819, CaLC1855 and CaLC1875, Gillian Milne for help with EM, Aaron Mitchell for generously providing the transposon insertion mutant library, Jesus Pla for generously providing the hog1 hst7 mutant, and Cathy Collins for technical assistance.Peer reviewedPublisher PD
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