383 research outputs found

    Prediction and observation of tin and silver plasmas with index of refraction greater than one in the soft x-ray range

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    Includes bibliographical references (pages 016404-6-016404-7).We present the calculated prediction and the experimental confirmation that doubly ionized Ag and Sn plasmas can have an index of refraction greater than one for soft x-ray wavelengths. Interferometry experiments conducted using a capillary discharge soft x-ray laser operating at a wavelength of 46.9 nm (26.44 eV) confirm that in few times ionized laser-created plasmas of these elements the anomalous dispersion from bound electrons can dominate the free electron contribution, making the index of refraction greater than one. The results confirm that bound electrons can strongly influence the index of refraction of numerous plasmas over abroad range of soft x-ray wavelengths confirming recent observations. The understanding of index of refraction at short wavelengths will become even more essential during the next decade as x-ray free electron lasers will become available to probe a wider variety of plasmas at higher densities and shorter wavelengths

    Case ascertainment uncertainties in prevalence surveys of Parkinson's disease

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    Using unpublished data from five completed prevalence surveys of Parkinson's disease (PD), we investigated case ascertainment uncertainties that potentially have a direct effect on prevalence. These uncertainties arise from the choice of diagnostic criteria, the choice of screening method, and the amount of information lost because of nonresponse. The surveys were conducted in Argentina, India, China, Italy, and the Netherlands. Our analyses consisted of simple comparisons of prevalence results, positive predictive values (a screening measure), and nonresponse percentages. We found that (a) prevalence comparisons between surveys have diminished value if the surveys used different diagnostic criteria for PD; (b) screening performance may be affected adversely if symptom questions are answered by one family member for the entire family living together rather than by each family member individually; and (c) nonresponse from refusal or unavailability does not necessarily lead to bias, but special caution may be appropriate with prevalence results pertaining to elderly women

    Minimally invasive laparoscopic and robot-assisted emergency treatment of strangulated giant hiatal hernias: report of five cases and literature review

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    Background Giant hiatal hernia (GHH) is a condition where one-third of the stomach migrates into the thorax. Nowadays, laparoscopic treatment gives excellent postoperative outcomes. Strangulated GHH is rare, and its emergent repair is associated with significant morbidity and mortality rates. We report a series of five cases of strangulated GHH treated by a minimally invasive laparoscopic and robot-assisted approach, together with a systematic review of the literature. Methods During 10 years (December 2009–December 2019), 31 patients affected by GHH were treated by robot-assisted or conventional laparoscopic surgical approach. Among them, five cases were treated in an emergency setting. We performed a PubMed MEDLINE search about the minimally invasive emergent treatment of GHH, selecting 18 articles for review. Results The five cases were male patients with a mean age of 70 ± 18 years. All patients referred to the emergency service complaining of severe abdominal and thoracic pain, nausea and vomiting. CT scan and endoscopy were the main diagnostic tools. All patients showed stable hemodynamic conditions so that they could undergo a minimally invasive attempt. The surgical approach was robotic-assisted in three patients (60%) and laparoscopic in two (40%). Patients reported no complications or recurrences. Conclusion Reviewing current literature, no general recommendations are available about the emergent treatment of strangulated hiatal hernia. Acute mechanical outlet obstruction, ischemia of gastric wall or perforation and severe bleeding are the reasons for an emergent surgical indication. In stable conditions, a minimally invasive approach is often feasible. Moreover, the robot-assisted approach, allowing a stable 3D view and using articulated instruments, represents a reasonable option in challenging situations

    A Genomic Pathway Approach to a Complex Disease: Axon Guidance and Parkinson Disease

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    While major inroads have been made in identifying the genetic causes of rare Mendelian disorders, little progress has been made in the discovery of common gene variations that predispose to complex diseases. The single gene variants that have been shown to associate reproducibly with complex diseases typically have small effect sizes or attributable risks. However, the joint actions of common gene variants within pathways may play a major role in predisposing to complex diseases (the paradigm of complex genetics). The goal of this study was to determine whether polymorphism in a candidate pathway (axon guidance) predisposed to a complex disease (Parkinson disease [PD]). We mined a whole-genome association dataset and identified single nucleotide polymorphisms (SNPs) that were within axon-guidance pathway genes. We then constructed models of axon-guidance pathway SNPs that predicted three outcomes: PD susceptibility (odds ratio = 90.8, p = 4.64 × 10−38), survival free of PD (hazards ratio = 19.0, p = 5.43 × 10−48), and PD age at onset (R2 = 0.68, p = 1.68 × 10−51). By contrast, models constructed from thousands of random selections of genomic SNPs predicted the three PD outcomes poorly. Mining of a second whole-genome association dataset and mining of an expression profiling dataset also supported a role for many axon-guidance pathway genes in PD. These findings could have important implications regarding the pathogenesis of PD. This genomic pathway approach may also offer insights into other complex diseases such as Alzheimer disease, diabetes mellitus, nicotine and alcohol dependence, and several cancers

    The host galaxies and black-hole:galaxy mass ratios of luminous quasars at z~4

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    We present and analyse the deepest, high-quality Ks-band images ever obtained of luminous quasars at z~4, in an attempt to determine the basic properties of their host galaxies less than 1 Gyr after the first recorded appearance of black holes with Mbh > 10^9 Msol. To maximise the robustness of our results we have carefully selected two SDSS quasars at z~4. These quasars are representative of the most luminous quasars known at this epoch but they also, crucially, lie within 40 arcsec of comparably-bright foreground stars (required for accurate PSF definition), and have redshifts which ensure line-free Ks-band imaging. The data were obtained in excellent seeing (<0.4-arcsec) at the ESO VLT with integration times of ~5.5 hours per source. Via carefully-controlled separation of host-galaxy and nuclear light, we estimate the luminosities and stellar masses of the host galaxies, and set constraints on their half-light radii. The quasar host galaxies have K-band luminosities similar to radio galaxies at comparable redshifts, suggesting that these quasar hosts are also among the most massive galaxies in existence at this epoch. However, the quasar hosts are a factor ~5 smaller than the host galaxies of luminous low-redshift quasars. We estimate the stellar masses of the z~4 host galaxies to lie in the range 2-10x10^11 Msol, and use the CIV emission line in the Sloan spectra to estimate the masses of their black holes. The results imply a black-hole:host-galaxy mass ratio Mbh:Mgal~0.01-0.05. This is an order of magnitude higher than typically seen in the low-redshift Universe, and is consistent with existing evidence for a systematic growth in this mass ratio with increasing redshift, at least for objects selected as powerful AGN.Comment: 10 pages, 6 figure

    Anti-HLA donor-specific antibodies in allogeneic stem cell transplantation: management and desensitization protocol

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    The role of antibodies directed against the human leukocyte antigen (HLA) system has been well analyzed in rejection of solid organ transplantations [1, 2] and in transfusion medicine [3]. In the setting of allogeneic hematopoietic stem cells transplantation (HSCT), only in the recent years their importance has been better defined, even though anti-HLA antibodies are frequently detectable in hematologic patients, due to sensitization from multiple transfusions, usually before the introduction of online universal leukoreduction, previous transplantations, and pregnancies in female patients

    Meeting Report: Consensus Statement—Parkinson’s Disease and the Environment: Collaborative on Health and the Environment and Parkinson’s Action Network (CHE PAN) Conference 26–28 June 2007

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    BackgroundParkinson's disease (PD) is the second most common neurodegenerative disorder. People with PD, their families, scientists, health care providers, and the general public are increasingly interested in identifying environmental contributors to PD risk.MethodsIn June 2007, a multidisciplinary group of experts gathered in Sunnyvale, California, USA, to assess what is known about the contribution of environmental factors to PD.ResultsWe describe the conclusions around which they came to consensus with respect to environmental contributors to PD risk. We conclude with a brief summary of research needs.ConclusionsPD is a complex disorder, and multiple different pathogenic pathways and mechanisms can ultimately lead to PD. Within the individual there are many determinants of PD risk, and within populations, the causes of PD are heterogeneous. Although rare recognized genetic mutations are sufficient to cause PD, these account for &lt; 10% of PD in the U.S. population, and incomplete penetrance suggests that environmental factors may be involved. Indeed, interplay among environmental factors and genetic makeup likely influences the risk of developing PD. There is a need for further understanding of how risk factors interact, and studying PD is likely to increase understanding of other neurodegenerative disorders

    A Trial of Wound Irrigation in the Initial Management of Open Fracture Wounds

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    Copyright © 2015 Massachusetts Medical Society. BACKGROUND The management of open fractures requires wound irrigation and dridement to remove contaminants, but the effectiveness of various pressures and solutions for irrigation remains controversial. We investigated the effects of castile soap versus normal saline irrigation delivered by means of high, low, or very low irrigation pressure. METHODS In this study with a 2-by-3 factorial design, conducted at 41 clinical centers, we randomly assigned patients who had an open fracture of an extremity to undergo irrigation with one of three irrigation pressures (high pressure [\u3e20 psi], low pressure [5 to 10 psi], or very low pressure [1 to 2 psi]) and one of two irrigation solutions (castile soap or normal saline). The primary end point was reoperation within 12 months after the index surgery for promotion of wound or bone healing or treatment of a wound infection. RESULTS A total of 2551 patients underwent randomization, of whom 2447 were deemed eligible and included in the final analyses. Reoperation occurred in 109 of 826 patients (13.2%) in the high-pressure group, 103 of 809 (12.7%) in the low-pressure group, and 111 of 812 (13.7%) in the very-low-pressure group. Hazard ratios for the three pairwise comparisons were as follows: for low versus high pressure, 0.92 (95% confidence interval [CI], 0.70 to 1.20; P = 0.53), for high versus very low pressure, 1.02 (95% CI, 0.78 to 1.33; P = 0.89), and for low versus very low pressure, 0.93 (95% CI, 0.71 to 1.23; P = 0.62). Reoperation occurred in 182 of 1229 patients (14.8%) in the soap group and in 141 of 1218 (11.6%) in the saline group (hazard ratio, 1.32, 95% CI, 1.06 to 1.66; P = 0.01). CONCLUSIONS The rates of reoperation were similar regardless of irrigation pressure, a finding that indicates that very low pressure is an acceptable, low-cost alternative for the irrigation of open fractures. The reoperation rate was higher in the soap group than in the saline group. (Funded by the Canadian Institutes of Health Research and others; FLOW ClinicalTrials.gov number, NCT00788398

    Understanding 6th-century barbarian social organization and migration through paleogenomics.

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    Despite centuries of research, much about the barbarian migrations that took place between the fourth and sixth centuries in Europe remains hotly debated. To better understand this key era that marks the dawn of modern European societies, we obtained ancient genomic DNA from 63 samples from two cemeteries (from Hungary and Northern Italy) that have been previously associated with the Longobards, a barbarian people that ruled large parts of Italy for over 200 years after invading from Pannonia in 568 CE. Our dense cemetery-based sampling revealed that each cemetery was primarily organized around one large pedigree, suggesting that biological relationships played an important role in these early medieval societies. Moreover, we identified genetic structure in each cemetery involving at least two groups with different ancestry that were very distinct in terms of their funerary customs. Finally, our data are consistent with the proposed long-distance migration from Pannonia to Northern Italy.This work was supported by National Science Foundation award #1450606, the Anneliese Maier Research Award of the Alexander von Humboldt Foundation, the Max Planck Society, the German Federal Ministry for Education and Research, the Swedish Riksbankens Jubieleumfond, the Gerard B. Lambert Foundation, the Institute for Advanced Study Director’s Office, and the Italian Ministry for University and Research Department of Excellence Program
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