420 research outputs found

    In vitro evaluation of electrospun blends of gelatin and PCL for application as a partial thickness corneal graft

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    The advent of innovative surgical procedures utilizing partial thickness corneal grafts has created a need for the development of synthetic implants to recreate corneal stromal tissue. This work evaluates electrospun gelatin and polycaprolactone (PCL) scaffolds as a potential biomaterial suitable for use in regeneration of corneal stromal tissue. Electrospun gelatin has been used for many years in tissue engineering, however, post‐production modification, such as crosslinking, is usually required to mechanically strengthen such scaffolds. This paper aims therefore to compare glutaraldehyde (GA) cross‐linked electrospun gelatin scaffolds with electrospun blends of gelatin and PCL at different ratios. Scaffolds were fabricated using electrospinning and characterized by scanning electron microscopy, Attenuated Total Reflectance‐Fourier Transform Infrared Spectroscopy (ATR‐FTIR), and tensile testing. To evaluate biocompatibility, primary human corneal stromal cells (hCSC) were seeded upon the scaffolds to assess adherence, proliferation and phenotype. Results demonstrated that scaffolds fabricated from mixtures of gelatin and PCL showed increased mechanical strength and plasticity compared to scaffolds fabricated from GA cross‐linked gelatin alone. In addition, scaffolds fabricated from PCL and gelatin showed comparable support of hCSC adhesion and proliferation. In conclusion, blended mixtures of gelatin and PCL can be considered as an option in the selection of corneal repair materials in the future

    A cohort study of post-weaning multisystemic wasting syndrome and PCV2 in 178 pigs from birth to 14 weeks on a single farm in England

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    Our hypothesis was that pigs that develop post-weaning multisystemic wasting syndrome (PMWS) are detectable from an early age with signs of weight loss and other clinical and serological abnormalities. Therefore, the objective of this study was to investigate the temporally varying and fixed events linked with the clinical incidence of PMWS by comparing affected and unaffected pigs in a cohort of 178 male piglets. Piglets were enrolled at birth and examined each week. Samples of blood were collected at regular intervals. The exposures measured were porcine circovirus type 2 (PCV2) antibody titres in all 178 and PCV2 antigen in a subset of 75 piglets. We also observed piglet health and measured their weight, and a post-mortem examination was performed by an external laboratory on all pigs between 6 and 14 weeks of age that died. From the cohort, 14 (8%) pigs died from PMWS and 4% from other causes. A further 37 pigs between 6 and 14 weeks of age died from PMWS (30) and ileitis and other causes (7). PMWS was only apparent in pigs from 1 to 2 weeks before death when they wasted rapidly. There were no other characteristic clinical signs and no obvious gross clinical lesions post-mortem. There was no strong link with PCV2 antibody throughout life but PCV2 antigen level was higher from 4 to 6 weeks of age in pigs that died from PMWS compared with pigs that died from other causes

    Fusion of secretory vesicles isolated from rat liver

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    Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells. Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system. The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences

    Have we seen the geneticisation of society? Expectations and evidence

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    Abby Lippman’s geneticization thesis, of the early 1990s, argued and anticipated that with the rise of genetics, increasing areas of social and health related activities would come to be understood and defined in genetic terms leading to major changes in society, medicine and health care. We review the considerable literature on geneticization and consider how the concept stands both theoretically and empirically across scientific, clinical, popular and lay discourse and practice. Social science scholarship indicates that relatively little of the original claim of the geneticization thesis has been realised, highlighting the development of more complex and dynamic accounts of disease in scientific discourse and the complexity of relationships between bioscientific, clinical and lay understandings. This scholarship represents a shift in social science understandings of the processes of sociotechnical change, which have moved from rather simplistic linear models to an appreciation of disease categories as multiply understood. Despite these shifts, we argue that a genetic imaginary persists, which plays a performative role in driving investments in new gene-based developments. Understanding the enduring power of this genetic imaginary and its consequences remains a key task for the social sciences, one which treats ongoing genetic expectations and predictions in a sceptical yet open way

    The legacy of Corrado Gini in population studies

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    This volume contains 12 papers that range over many different research subjects, taking in many of the population questions that, directly or indirectly, absorbed Corrado Gini as demographer and social scientist over several decades. They vary from the analysis of the living conditions and behaviours of the growing foreign population (measurements and methods of analysis, socio-economic conditions and health, ethnic residential segregation, sex-ratio at birth), to studies on the homogamy of couples; from population theories (with reference to the cyclical theory of populations) to the modelling approach to estimating mortality in adult ages or estimating time transfers, by age and sex, related to informal child care and adult care; from historical studies that take up themes dear to Gini (such as the estimates of Italian military deaths in WWI), to the application of Gini’s classical measurements to studying significant phenomena today (transition to adulthood and leaving the parental home, health care, disabled persons and social integration). The subjects and measurements that appear here are not intended to exhaust the broad spectrum of Gini’s research work in the demographic and social field (nor could they), but they can make up a part of the intersection between his vast legacy and some interesting topics in current research, some of which were not even imaginable in the mid twentieth century. Looking at the many contributions that celebrated Gini in Treviso and thinking about his legacy, it seems possible to identify at least two typologies of approach, to be found in this issue of the journal, too. On the one hand, there are contributions that aim to retrieve and discuss themes, methodologies and measurements dealt with or used by Gini so as to evaluate their present relevance and importance in the current scholarly debate. On the other, there are contributions that deal with topics that are far from Gini’s work, as they study very recent phenomena, but actually, among other things, make use of methods and indicators devised by Gini that are now so much part of the common currency of methodology, so they don’t require explicit reference to their Author

    Fitting the integrated Spectral Energy Distributions of Galaxies

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    Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

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    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Is American Public Administration Detached From Historical Context?: On the Nature of Time and the Need to Understand It in Government and Its Study

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    The study of public administration pays little attention to history. Most publications are focused on current problems (the present) and desired solutions (the future) and are concerned mainly with organizational structure (a substantive issue) and output targets (an aggregative issue that involves measures of both individual performance and organizational productivity/services). There is much less consideration of how public administration (i.e., organization, policy, the study, etc.) unfolds over time. History, and so administrative history, is regarded as a “past” that can be recorded for its own sake but has little relevance to contemporary challenges. This view of history is the product of a diminished and anemic sense of time, resulting from organizing the past as a series of events that inexorably lead up to the present in a linear fashion. To improve the understanding of government’s role and position in society, public administration scholarship needs to reacquaint itself with the nature of time.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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