191 research outputs found

    Single Particle Operators and their Correlators in Free N=4 SYM

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    We consider a set of half-BPS operators in N = 4 super Yang-Mills theory which are appropriate for describing single-particle states of superstring theory on AdS5 Ă— S5. These single-particle operators are defined to have vanishing two-point functions with all multi-trace operators and therefore correspond to admixtures of single- and multi-traces. We find explicit formulae for all single-particle operators and for their two-point function normalisation. We show that single-particle U(N) operators belong to the SU(N) subspace, thus for length greater than one they are simply the SU(N) single-particle operators. Then, we point out that at large N, as the length of the operator increases, the single-particle operator naturally interpolates between the single-trace and the S3 giant graviton. At finite N, the multi-particle basis, obtained by taking products of the single-particle operators, gives a new basis for all half-BPS states, and this new basis naturally cuts off when the length of any of the single-particle operators exceeds the number of colours. From the two-point function orthogonality we prove a multipoint orthogonality theorem which implies vanishing of all near-extremal correlators. We then compute all maximally and next-to-maximally extremal free correlators, and we discuss features of the correlators when the extremality is lowered. Finally, we describe a half-BPS projection of the operator product expansion on the multi-particle basis which provides an alternative construction of four- and higher-point functions in the free theory

    Bilateral native nephrectomy improves renal isograft function in rats

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    Bilateral native nephrectomy improves renal isograft function in rats. Bilateral native nephrectomy has been suggested to improve renal allograft survival in man. This effect may be most prominent in patients experiencing acute tubular necrosis following transplantation. Thus, native kidneys may alter the course of ischemic acute tubular necrosis in the transplanted kidney. In the present studies, we utilized an experimental model of syngeneic transplantation in which rejection does not occur. We studied Lewis rat renal isografts transplanted into littermates following sham, unilateral or bilateral native nephrectomy. In a fourth group of rats, we evaluated the importance of native kidney excretory function by studying isografts transplanted into littermates with bilaterally obstructed native kidneys. Renal blood flow and excretory function were measured in vivo, eight days following transplantation. Renal excretory function of isografts transplanted into animals following bilateral native nephrectomy was similar to normal nontrans-planted Lewis kidneys. The presence of either one or both functioning native kidneys significantly reduced isograft inulin clearance, PAH clearance, and blood flow. However, when isografts were transplanted into Lewis rats with bilaterally obstructed native kidneys, renal isograft inulin clearance and blood flow were not significantly impaired Non-transplanted kidneys demonstrated “functional hypertrophy” following contralateral nephrectomy, with glomerular filtration rate and renal blood flow increasing by approximately 50%. In contrast, isograft glomerular filtration rate in animals following bilateral native nephrectomy was equivalent to that of single kidneys from normal animals with both kidneys in situ. However, renal blood flow of isografts from these animals increased to the same level as nontransplanted Lewis kidneys following contralateral nephrectomy. Histological examination of isografts from animals with functioning native kidneys in situ demonstrated extensive disruption of normal renal architecture with tubular and interstitial injury. This was in marked contrast to the appearance of Lewis–Brown Norway allografts, to isografts from animals following bilateral native nephrectomy, and to isografts from animals with bilaterally obstructed native kidneys. In Lewis–Brown Norway allografts, there was evidence of rejection with active inflammatory cell infiltration, arteriolitis and venulitis. In isografts from animals following bilateral native nephrectomy or with bilaterally obstructed native kidneys, renal architecture was normal. Thus, the detrimental effect of native kidneys on isograft function may be related to impaired recovery from ischemia or potentiation of ischemic injury which occurs during the transplantation procedure

    Plurality in multi-disciplinary research: multiple institutional affiliations are associated with increased citations

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    Background The institutional affiliations and associated collaborative networks that scientists foster during their research careers are salient in the production of high-quality science. The phenomenon of multiple institutional affiliations and its relationship to research output remains relatively unexplored in the literature. Methods We examined 27,612 scientific articles, modelling the normalized citation counts received against the number of authors and affiliations held. Results In agreement with previous research, we found that teamwork is an important factor in high impact papers, with average citations received increasing concordant with the number of co-authors listed. For articles with more than five co-authors, we noted an increase in average citations received when authors with more than one institutional affiliation contributed to the research. Discussion Multiple author affiliations may play a positive role in the production of high-impact science. This increased researcher mobility should be viewed by institutional boards as meritorious in the pursuit of scientific discovery

    The effect of transverse ocular magnification adjustment on macular thickness profile in different refractive errors in community-based adults

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    Purpose Changes in retinal thickness are common in various ocular diseases. Transverse magnification due to differing ocular biometrics, in particular axial length, affects measurement of retinal thickness in different regions. This study evaluated the effect of axial length and refractive error on measured macular thickness in two community-based cohorts of healthy young adults. Methods A total of 2160 eyes of 1247 community-based participants (18–30 years; 23.4% myopes, mean axial length = 23.6mm) were included in this analysis. Macular thickness measurements were obtained using a spectral-domain optical coherence tomography (which assumes an axial length of 24.385mm). Using a custom program, retinal thickness data were extracted at the 9 Early Treatment of Diabetic Retinopathy Study (ETDRS) regions with and without correction for transverse magnificent effects, with the corrected measurements adjusting according to the participant’s axial length. Linear mixed models were used to analyse the effect of correction and its interaction with axial length or refractive group on retinal thickness. Results The raw measures (uncorrected for axial length) underestimated the true retinal thickness at the central macula, while overestimating at most non-central macular regions. There was an axial length by correction interaction effect in all but the nasal regions (all p\u3c0.05). For each 1mm increase in axial length, the central macular thickness is overestimated by 2.7–2.9μm while thicknesses at other regions were underestimated by 0.2–4.1μm. Based on the raw thickness measurements, myopes have thinner retinas than non-myopes at most non-central macular. However, this difference was no longer significant when the corrected data was used. Conclusion In a community-based sample, the raw measurements underestimate the retinal thickness at the central macula and overestimate the retinal thickness at non-central regions of the ETDRS grid. The effect of axial length and refractive error on retinal thickness is reduced after correcting for transverse magnification effects resulting from axial length differences

    A study protocol for testing the feasibility of a randomised stepped wedge cluster design to investigate a Community Health Intervention through Musical Engagement (CHIME) for perinatal mental health in The Gambia

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    Abstract: Background: Perinatal mental health problems affect up to one in five women worldwide. Mental health problems in the perinatal period are a particular challenge in low- and middle-income countries (LMICs) where they can be at least twice as frequent as in higher-income countries. It is thus of high priority to develop new low-cost, low-resource, non-stigmatising and culturally appropriate approaches to reduce symptoms of anxiety and depression perinatally, for the benefit of both mother and child. Music-centred approaches may be particularly useful in The Gambia since a range of musical practices that specifically engage pregnant women and new mothers already exist. Methods: This protocol is for a study to examine the feasibility of undertaking a stepped wedge trial to test how a Community Health Intervention through Musical Engagement (CHIME) could be beneficial in alleviating perinatal mental distress in The Gambia. In this study, we plan to recruit 120 pregnant women (n = 60 intervention, n = 60 control) at four antenatal clinics over two 6-week stepped sequences. Women in the intervention will participate in weekly group-singing sessions, led by local Kanyeleng singing groups, for 6 weeks. The control group will receive standard care. We will assess symptoms of anxiety and depression using the Edinburgh Postnatal Depression Scale (EPDS) and the Self-Reporting Questionnaire (SRQ-20). The feasibility of the design will be assessed through recruitment, retention and attrition rates of participants, clinics' adherence to the schedule and completeness of data by site. Qualitative interviews and video and audio recordings will be used to evaluate the acceptability of the intervention. Discussion: This feasibility trial will allow us to determine whether a larger trial with the same intervention and target group is feasible and acceptable in The Gambia. Trial registration: Retrospectively registered (24/01/2019) with Pan African Clinical Trials Registry (PACTR): PACTR201901917619299

    Community psychosocial music intervention (CHIME) to reduce antenatal common mental disorder symptoms in The Gambia: a feasibility trial

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    Objectives: Examine the feasibility of a Community Health Intervention through Musical Engagement (CHIME) in The Gambia to reduce common mental disorder (CMD) symptoms in pregnant women. Design: Feasibility trial testing a randomised stepped-wedge cluster design. Setting: Four local antenatal clinics. Participants: Women who were 14–24 weeks pregnant and spoke Mandinka or Wolof were recruited into the intervention (n=50) or control group (n=74). Intervention: Music-based psychosocial support sessions designed and delivered by all-female fertility societies. Sessions lasted 1 hour and were held weekly for 6 weeks. Delivered to groups of women with no preselection. Sessions were designed to lift mood, build social connection and provide health messaging through participatory music making. The control group received standard antenatal care. Outcomes: Demographic, feasibility, acceptability outcomes and the appropriateness of the study design were assessed. Translated measurement tools (Self-Reporting Questionnaire (SRQ-20); Edinburgh Postnatal Depression Scale (EPDS)) were used to assess CMD symptoms at baseline, post-intervention and 4-week follow-up. Results: All clinics and 82% of women approached consented to take part. A 33% attrition rate across all time points was observed. 72% in the intervention group attended at least three sessions. Audio and video analysis confirmed fidelity of the intervention and a thematic analysis of participant interviews demonstrated acceptability and positive evaluation. Results showed a potential beneficial effect with a reduction of 2.13 points (95% CI (0.89 to 3.38), p<0.01, n=99) on the SRQ-20 and 1.98 points (95% CI (1.06 to 2.90), p<0.01, n=99) on the EPDS at the post-intervention time point for the intervention group compared with standard care. Conclusion: Results demonstrate that CHIME is acceptable and feasible in The Gambia. To our knowledge, CHIME is the first example of a music-based psychosocial intervention to be applied to perinatal mental health in a low- and middle-income country context

    A study protocol for testing the feasibility of a randomised stepped wedge cluster design to investigate a Community Health Intervention through Musical Engagement (CHIME) for perinatal mental health in The Gambia

    Get PDF
    Background: Perinatal mental health problems affect up to one in five women worldwide. Mental health problems in the perinatal period are a particular challenge in low- and middle-income countries (LMICs) where they can be at least twice as frequent as in higher-income countries. It is thus of high priority to develop new low-cost, low-resource, non-stigmatising and culturally appropriate approaches to reduce symptoms of anxiety and depression perinatally, for the benefit of both mother and child. Music-centred approaches may be particularly useful in The Gambia since a range of musical practices that specifically engage pregnant women and new mothers already exist. Methods: This protocol is for a study to examine the feasibility of undertaking a stepped wedge trial to test how a Community Health Intervention through Musical Engagement (CHIME) could be beneficial in alleviating perinatal mental distress in The Gambia. In this study, we plan to recruit 120 pregnant women (n = 60 intervention, n = 60 control) at four antenatal clinics over two 6-week stepped sequences. Women in the intervention will participate in weekly group-singing sessions, led by local Kanyeleng singing groups, for 6 weeks. The control group will receive standard care. We will assess symptoms of anxiety and depression using the Edinburgh Postnatal Depression Scale (EPDS) and the Self-Reporting Questionnaire (SRQ-20). The feasibility of the design will be assessed through recruitment, retention and attrition rates of participants, clinics' adherence to the schedule and completeness of data by site. Qualitative interviews and video and audio recordings will be used to evaluate the acceptability of the intervention. Discussion: This feasibility trial will allow us to determine whether a larger trial with the same intervention and target group is feasible and acceptable in The Gambia

    Pre-transplant CDKN2A expression in kidney biopsies predicts renal function and is a future component of donor scoring criteria

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    CDKN2A is a proven and validated biomarker of ageing which acts as an off switch for cell proliferation. We have demonstrated previously that CDKN2A is the most robust and the strongest pre-transplant predictor of post- transplant serum creatinine when compared to “Gold Standard” clinical factors, such as cold ischaemic time and donor chronological age. This report shows that CDKN2A is better than telomere length, the most celebrated biomarker of ageing, as a predictor of post-transplant renal function. It also shows that CDKN2A is as strong a determinant of post-transplant organ function when compared to extended criteria (ECD) kidneys. A multivariate analysis model was able to predict up to 27.1% of eGFR at one year post-transplant (p = 0.008). Significantly, CDKN2A was also able to strongly predict delayed graft function. A pre-transplant donor risk classification system based on CDKN2A and ECD criteria is shown to be feasible and commendable for implementation in the near future

    HLA and cross-reactive antigen group matching for cadaver kidney allocation

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    Background. Allocation of cadaver kidneys by graded human leukocyte antigen (HLA) compatibility scoring arguably has had little effect on overall survival while prejudicing the transplant candidacy of African-American and other hard to match populations. Consequently, matching has been proposed of deduced amino acid residues of the individual HLA molecules shared by cross- reactive antigen groups (CREGs). We have examined the circumstances under which compatibility with either method impacted graft survival. Methods. Using Cox proportional hazards regression modeling, we studied the relationship between levels of conventional HLA mismatch and other donor and recipient factors on primary cadaver kidney survival between 1981 and 1995 at the University of Pittsburgh (n=1,780) and in the United Network for Organ Sharing (UNOS) Scientific Registry during 1991-1995 (n=31,291). The results were compared with those obtained by the matching of amino acid residues that identified CREG-compatible cases with as many as four (but not five and six) HLA mismatches. Results. With more than one HLA mismatch (>85% of patients in both series), most of the survival advantage of a zero mismatch was lost. None of the HLA loci were 'weak.' In the UNOS (but not Pittsburgh) category of one-HLA mismatch (n=1334), a subgroup of CREG-matched recipients (35.3%) had better graft survival than the remaining 64.7%, who were CREG-mismatched. There was no advantage of a CREG match in the two- to four-HLA incompatibility tiers. Better graft survival with tacrolimus was observed in both the Pittsburgh and UNOS series. Conclusions. Obligatory national sharing of cadaver kidneys is justifiable only for zero-HLA-mismatched kidneys. The potential value of CREG matching observed in the one-HLA-mismatched recipients of the UNOS (but not the Pittsburgh) experience deserves further study
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