96 research outputs found

    Levels of evidence in plastic surgery – Trends and comparison with five other surgical specialties

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    Background: Categorising research by level of evidence (LOE) is an important evidence-based medicine initiative. Our objective was to assess the change in LOEs in plastic surgery from 2003 to 2013 and compared this with five other surgical specialties. Methods: A search for all research articles published in the top three general plastic surgery journals (ranked by impact factor) was conducted for 2003 and 2013. Articles were then labelled as LOE 1–5 and compared to other specialties. Results: Mean LOE for plastic surgery improved by 4.1 % from 3.86 (95 % confidence interval 3.81–3.91) to 3.70 (95 % confidence interval 3.64–3.74) from 2003 to 2013 respectively. All six surgical specialties improved their mean LOE (range 3.7 to 10.9 %). By mean LOE, plastic surgery continues to rank five out of six. Conclusions: Plastic surgery is tending towards higher levels of evidence at a slow pace. The specialty must continue to drive towards higher levels of evidence. Level of Evidence: Not ratable

    Nanostructure and paramagnetic centres in diamond-like carbon: Effect of Ar dilution in PECVD process

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    Diamond-like carbon (DLC) films were deposited utilising plasma enhanced chemical vapour deposition (PECVD) with acetylene precursor, diluted with 0 – 45% argon. Electron paramagnetic resonance (EPR) measurements show the presence of one paramagnetic centre with no change in spin population over the range of film deposition conditions. However, the EPR linewidth decreases with increasing argon content of the precursor mix, suggesting an enhancement of motional narrowing due to an increase in electron delocalization, related to an increase in the sp2 cluster size. Atomic force microscopy (AFM) measurements indicate the surface of the DLC is formed of nanoscale asperities of material. With radii of tens of nanometres for films deposited with zero argon, the size of the features increases with the argon dilution of the acetylene. Energy dispersive x-ray analysis and electrical measurements further elucidate the changes in film structure

    Remote conditioning or erythropoietin before surgery primes kidneys to clear ischemia-reperfusion-damaged cells: a renoprotective mechanism?

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    Acute kidney injury is common, serious with no specific treatment. Ischemia-reperfusion is a common cause of acute kidney injury (AKI). Clinical trials suggest that preoperative erythropoietin (EPO) or remote ischemic preconditioning may have a renoprotective effect. Using a porcine model of warm ischemia-reperfusion-induced AKI (40-min bilateral cross-clamping of renal arteries, 48-h reperfusion), we examined the renoprotective efficacy of EPO (1,000 iu/kg iv.) or remote ischemic preconditioning (3 cycles, 5-min inflation/deflation to 200 mmHg of a hindlimb sphygmomanometer cuff). Ischemia-reperfusion induced significant kidney injury at 24 and 48 h (χ(2), 1 degree of freedom, >10 for 6/7 histopathological features). At 2 h, a panel of biomarkers including plasma creatinine, neutrophil gelatinase-associated lipocalin, and IL-1β, and urinary albumin:creatinine could be used to predict histopathological injury. Ischemia-reperfusion increased cell proliferation and apoptosis in the renal cortex but, for pretreated groups, the apoptotic cells were predominantly intratubular rather than interstitial. At 48-h reperfusion, plasma IL-1β and the number of subcapsular cells in G2-M arrest were reduced after preoperative EPO, but not after remote ischemic preconditioning. These data suggest an intrarenal mechanism acting within cortical cells that may underpin a renoprotective function for preoperative EPO and, to a limited extent, remote ischemic preconditioning. Despite equivocal longer-term outcomes in clinical studies investigating EPO as a renoprotective agent in AKI, optimal clinical dosing and administration have not been established. Our data suggest further clinical studies on the potential renoprotective effect of EPO and remote ischemic preconditioning are justified

    Chemostratigraphy of Neoproterozoic carbonates: implications for 'blind dating'

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    The delta C-13(carb) and Sr-87/Sr-86 secular variations in Neoproteozoic seawater have been used for the purpose of 'isotope stratigraphy' but there are a number of problems that can preclude its routine use. In particular, it cannot be used with confidence for 'blind dating'. The compilation of isotopic data on carbonate rocks reveals a high level of inconsistency between various carbon isotope age curves constructed for Neoproteozoic seawater, caused by a relatively high frequency of both global and local delta C-13(carb) fluctuations combined with few reliable age determinations. Further complication is caused by the unresolved problem as to whether two or four glaciations, and associated negative delta C-13(carb) excursions, can be reliably documented. Carbon isotope stratigraphy cannot be used alone for geological correlation and 'blind dating'. Strontium isotope stratigraphy is a more reliable and precise tool for stratigraphic correlations and indirect age determinations. Combining strontium and carbon isotope stratigraphy, several discrete ages within the 590-544 Myr interval, and two age-groups at 660-610 and 740-690 Myr can be resolved

    Binding Energy of Charged Excitons in ZnSe-based Quantum Wells

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    Excitons and charged excitons (trions) are investigated in ZnSe-based quantum well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of magneto-optical spectroscopy. Binding energies of negatively () and positively (X+) charged excitons are measured as functions of quantum well width, free carrier density and in external magnetic fields up to 47 T. The binding energy of shows a strong increase from 1.4 to 8.9 meV with decreasing quantum well width from 190 to 29 A. The binding energies of X+ are about 25% smaller than the binding energy in the same structures. The magnetic field behavior of and X+ binding energies differ qualitatively. With growing magnetic field strength, increases its binding energy by 35-150%, while for X+ it decreases by 25%. Zeeman spin splittings and oscillator strengths of excitons and trions are measured and discussed

    Co-evolution of Structures and Controllers for Neubot Underwater Modular Robots

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    This article presents the first results of a project in underwater modular robotics, called Neubots. The goals of the projects are to explore, following Von Neumann’s ideas, potential mechanisms underlying self-organization and self-replication. We briefly explain the design features of the module units. We then present simulation results of the artificial co-evolution of body structures and neural controllers for locomotion. The neural controllers are inspired from the central pattern generators underlying locomotion in vertebrate animals. They are composed of multiple neural oscillators which are connected together by a specific type of coupling called synaptic spreading. The co-evolution of body and controller leads to interesting robots capable of efficient swimming. Interesting features of the neural controllers include the possibility to modulate the speed of locomotion by varying simple input signals, the robustness against perturbations, and the distributed nature of the controllers which makes them well suited for modular robotics

    The flyby anomaly: a multivariate analysis approach

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    [EN] The flyby anomaly is the unexpected variation of the asymptotic post-encounter velocity of a spacecraft with respect to the pre-encounter velocity as it performs a slingshot manoeuvre. This effect has been detected in, at least, six flybys of the Earth but it has not appeared in other recent flybys. In order to find a pattern in these, apparently contradictory, data several phenomenological formulas have been proposed but all have failed to predict a new result in agreement with the observations. In this paper we use a multivariate dimensional analysis approach to propose a fitting of the data in terms of the local parameters at perigee, as it would occur if this anomaly comes from an unknown fifth force with latitude dependence. Under this assumption, we estimate the range of this force around 300 km .Acedo Rodríguez, L. (2017). The flyby anomaly: a multivariate analysis approach. Astrophysics and Space Science. 362(2):1-7. doi:10.1007/s10509-017-3025-zS173622Acedo, L.: Adv. 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    The structure of PGC Morale Scale in American and Japanese aged: A further note

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    This study involves a further replication of cross-cultural comparison of the structure of the Philadelphia Geriatric Center Morale Scale (PGCMS). Using Japanese and American data sets, the present research replicates and extends the findings reported by Liang et al. (1987). In particular, the earlier findings that four PGCMS items behave differently in two cultures are replicated. The present study yields two additional observations. First, the invariance in the PGCMS can now be extended beyond the urban elderly residents studied by Liang et al. (1987) to the entire aged population in the U.S. and Japan. Second, this comparability is robust despite the elimination of correlated measurement errors from the earlier specifications and when several exogenous variables are controlled. Further, the impact of selected demographic variables on the PGCMS was evaluated. In addition, qualitative data from in-depth interviews provide further insights concerning the cultural differences in the expression of well-being.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42991/1/10823_2004_Article_BF00116576.pd

    Parental origin of sequence variants associated with complex diseases

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    To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldEffects of susceptibility variants may depend on from which parent they are inherited. Although many associations between sequence variants and human traits have been discovered through genome-wide associations, the impact of parental origin has largely been ignored. Here we show that for 38,167 Icelanders genotyped using single nucleotide polymorphism (SNP) chips, the parental origin of most alleles can be determined. For this we used a combination of genealogy and long-range phasing. We then focused on SNPs that associate with diseases and are within 500 kilobases of known imprinted genes. Seven independent SNP associations were examined. Five-one with breast cancer, one with basal-cell carcinoma and three with type 2 diabetes-have parental-origin-specific associations. These variants are located in two genomic regions, 11p15 and 7q32, each harbouring a cluster of imprinted genes. Furthermore, we observed a novel association between the SNP rs2334499 at 11p15 and type 2 diabetes. Here the allele that confers risk when paternally inherited is protective when maternally transmitted. We identified a differentially methylated CTCF-binding site at 11p15 and demonstrated correlation of rs2334499 with decreased methylation of that site.info:eu-repo/grantAgreement/EC/FP7/21807

    Meta-analysis of type 2 Diabetes in African Americans Consortium

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    Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe
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