6,375 research outputs found

    Progress with the Upgrade of the SPS for the HL-LHC Era

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    The demanding beam performance requirements of the High Luminosity (HL-) LHC project translate into a set of requirements and upgrade paths for the LHC injector complex. In this paper the performance requirements for the SPS and the known limitations are reviewed in the light of the 2012 operational experience. The various SPS upgrades in progress and still under consideration are described, in addition to the machine studies and simulations performed in 2012. The expected machine performance reach is estimated on the basis of the present knowledge, and the remaining decisions that still need to be made concerning upgrade options are detailed.Comment: 3 p. Presented at 4th International Particle Accelerator Conference (IPAC 2013

    Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

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    The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest gamma-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the nonthermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock

    The Olive Mills Waste Water (OMW) as an Organic Amendment for Controlling Wind Erosion in Southern Tunisia by Improving the Soil Surface Structure

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    Abstract: Spraying OMW on poor sandy soils in the olive orchards induces increasing of the organic matter content, the formation of aggregates and improving the soil structure stability. Hence, OMW can be an alternative and effective way to control this polluting sewage. Since 1995 a field experiment is running in an olive plot in chammakh-Zarzis, south Tunisia, where rates of 50, 100 and 200 m 3 of OMW were sprayed yearly on 1 ha fields with 16 olives trees per ha. Data collected in 2006 showed an increase in organic matter content from originally 0.06 to 1.27 %, an increase in the amount of aggregates > 2 mm to 34%, and an increase in the threshold friction velocity for deflation to 12 m sec -1 for the 200 m 3 ha -1 application

    Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and Monte Carlo radiative transfer modeling

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    We present 5.2-37.2 micron spectroscopy of the edge-on circumstellar disk CRBR 2422.8-3423 obtained using the InfraRed Spectrograph (IRS) of the Spitzer Space Telescope. The IRS spectrum is combined with ground-based 3-5 micron spectroscopy to obtain a complete inventory of solid state material present along the line of sight toward the source. We model the object with a 2D axisymmetric (effectively 3D) Monte Carlo radiative transfer code. It is found that the model disk, assuming a standard flaring structure, is too warm to contain the very large observed column density of pure CO ice, but is possibly responsible for up to 50% of the water, CO2 and minor ice species. In particular the 6.85 micron band, tentatively due to NH4+, exhibits a prominent red wing, indicating a significant contribution from warm ice in the disk. It is argued that the pure CO ice is located in the dense core Oph-F in front of the source seen in the submillimeter imaging, with the CO gas in the core highly depleted. The model is used to predict which circumstances are most favourable for direct observations of ices in edge-on circumstellar disks. Ice bands will in general be deepest for inclinations similar to the disk opening angle, i.e. ~70 degrees. Due to the high optical depths of typical disk mid-planes, ice absorption bands will often probe warmer ice located in the upper layers of nearly edge-on disks. The ratios between different ice bands are found to vary by up to an order of magnitude depending on disk inclination due to radiative transfer effects caused by the 2D structure of the disk. Ratios between ice bands of the same species can therefore be used to constrain the location of the ices in a circumstellar disk. [Abstract abridged]Comment: 49 pages, accepted for publication in Ap

    A unified approach to Darboux transformations

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    We analyze a certain class of integral equations related to Marchenko equations and Gel'fand-Levitan equations associated with various systems of ordinary differential operators. When the integral operator is perturbed by a finite-rank perturbation, we explicitly evaluate the change in the solution. We show how this result provides a unified approach to Darboux transformations associated with various systems of ordinary differential operators. We illustrate our theory by deriving the Darboux transformation for the Zakharov-Shabat system and show how the potential and wave function change when a discrete eigenvalue is added to the spectrum.Comment: final version that will appear in Inverse Problem

    C2D Spitzer-IRS spectra of disks around T Tauri stars: I. Silicate emission and grain growth

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    Infrared ~5--35 um spectra for 40 solar-mass T Tauri stars and 7 intermediate-mass Herbig Ae stars with circumstellar disks were obtained using the Spitzer Space Telescope as part of the c2d IRS survey. This work complements prior spectroscopic studies of silicate infrared emission from disks, which were focused on intermediate-mass stars, with observations of solar-mass stars limited primarily to the 10 um region. The observed 10 and 20 um silicate feature strengths/shapes are consistent with source-to-source variations in grain size. A large fraction of the features are weak and flat, consistent with um-sized grains indicating fast grain growth (from 0.1--1.0 um in radius). In addition, approximately half of the T Tauri star spectra show crystalline silicate features near 28 and 33 um indicating significant processing when compared to interstellar grains. A few sources show large 10-to-20 um ratios and require even larger grains emitting at 20 um than at 10 um. This size difference may arise from the difference in the depth into the disk probed by the two silicate emission bands in disks where dust settling has occurred. The 10 um feature strength vs. shape trend is not correlated with age or Halpha equivalent width, suggesting that some amount of turbulent mixing and regeneration of small grains is occurring. The strength vs. shape trend is related to spectral type, however, with M stars showing significantly flatter 10 um features (larger grain sizes) than A/B stars. The connection between spectral type and grain size is interpreted in terms of the variation in the silicate emission radius as a function of stellar luminosity, but could also be indicative of other spectral-type dependent factors (e.g, X-rays, UV radiation, stellar/disk winds, etc.).Comment: 17 pages, 13 figures, accepted for publication by ApJ, formatted with emulateapj using revtex4 v4.

    Representative Set of Objects in Rough Sets Based on Galois Connections

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    This paper introduces a novel definition, called representative set of objects of a decision class, in the framework of decision systems based on rough sets. The idea behind such a notion is to consider subsets of objects that characterize the different classes given by a decision system. Besides the formal definition of representative set of objects of a decision class, we present different mathematical properties of such sets and a relationship with classification tasks based on rough sets. © 2020, Springer Nature Switzerland AG

    Uterine bathing with sonography gel prior to IVF/ICSI-treatment in patients with endometriosis, a multicentre randomised controlled trial

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    STUDY QUESTION What is the effect of uterine bathing with sonography gel prior to IVF/ICSI-treatment on live birth rates after fresh embryo transfer in patients with endometriosis? SUMMARY ANSWER After formal interim analysis and premature ending of the trial, no significant difference between uterine bathing using a pharmacologically neutral sonography gel compared to a sham procedure on live birth rate after fresh embryo transfer in endometriosis patients (26.7% vs. 15.4%, relative risk (RR) 1.73, 95% confidence interval (CI) 0.81–3.72; P-value 0.147) could be found, although the trial was underpowered to draw definite conclusions. WHAT IS KNOWN ALREADY Impaired implantation receptivity contributes to reduced clinical pregnancy rates after IVF/ICSI-treatment in endometriosis patients. Previous studies have suggested a favourable effect of tubal flushing with Lipiodol® on natural conceptions. This benefit might also be explained by enhancing implantation through endometrial immunomodulation. Although recent studies showed no beneficial effect of endometrial scratching, the effect of mechanical stress by intrauterine infusion on the endometrium in endometriosis patients undergoing IVF/ICSI-treatment has not been investigated yet. STUDY DESIGN, SIZE, DURATION We performed a multicentre, patient-blinded, randomised controlled trial in which women were randomly allocated to either a Gel Infusion Sonography (GIS, intervention group) or a sham procedure (control group) prior to IVF/ICSI-treatment. Since recruitment was slow and completion of the study was considered unfeasible, the study was halted after inclusion of 112 of the planned 184 women. PARTICIPANTS/MATERIALS, SETTING, METHODS We included infertile women with surgically confirmed endometriosis ASRM stage I–IV undergoing IVF/ICSI-treatment. After informed consent, women were randomised to GIS with intrauterine instillation of ExEm-gel® or sonography with gel into the vagina (sham). This was performed in the cycle preceding the embryo transfer, on the day GnRH analogue treatment was started. The primary endpoint was live birth rate after fresh embryo transfer. Analysis was performed by both intention-to-treat and per-protocol. MAIN RESULTS AND THE ROLE OF CHANCE Between July 2014 to September 2018, we randomly allocated 112 women to GIS (n = 60) or sham procedure (n = 52). The live birth rate after fresh embryo transfer was 16/60 (26.7%) after GIS versus 8/52 (15.4%) after the sham (RR 1.73, 95% CI 0.81–3.72; P-value 0.147). Ongoing pregnancy rate was 16/60 (26.7%) after GIS versus 9/52 (17.3%) in the controls (RR 1.54, 95% CI 0.74–3.18). Miscarriage occurred in 1/60 (1.7%) after GIS versus 5/52 (9.6%) in the controls (RR 0.17, 95% CI 0.02–1.44) women. Uterine bathing resulted in a higher pain score compared with a sham procedure (visual analogue scale score 2.7 [1.3–3.5] vs. 1.0 [0.0–2.0], P < 0.001). There were two adverse events after GIS compared with none after sham procedures. LIMITATIONS, REASONS FOR CAUTION The study was terminated prematurely due to slow recruitment and trial fatigue. Therefore, the trial is underpowered to draw definite conclusions regarding the effect of uterine bathing with sonography gel on live birth rate after fresh embryo transfer in endometriosis patients undergoing IVF/ICSI-treatment. WIDER IMPLICATIONS OF THE FINDINGS We could not demonstrate a favourable effect of uterine bathing procedures with sonography gel prior to IVF/ICSI-treatment in patients with endometriosis. STUDY FUNDING/COMPETING INTEREST(S) Investigator initiated study. IQ Medical Ventures provided the ExEm FOAM® kits free of charge, they were not involved in the study design, data management, statistical analyses and/or manuscript preparation, etc. C.B.L. reports receiving grants from Ferring, Merck and Guerbet, outside the submitted work. C.B.L. is Editor-in-Chief of Human Reproduction. V.M. reports grants and other from Guerbet, outside the submitted work. B.W.M. reports grants from NHMRC (GNT1176437), personal fees from ObsEva, Merck and Merck KGaA, Guerbet and iGenomix, outside the submitted work. N.P.J. reports research funding from Abb-Vie and Myovant Sciences and consultancy for Vifor Pharma, Guerbet, Myovant Sciences and Roche Diagnostics, outside the submitted work. K.D. reports personal fees from Guerbet, outside the submitted work. The other authors do not report any conflicts of interest. No financial support was provided. TRIAL REGISTRATION NUMBER NL4025 (NTR4198) TRIAL REGISTRATION DATE 7 October 2013 DATE OF FIRST PATIENT’S ENROLMENT 22 July 201

    Cancer risk in children, adolescents, and young adults conceived by ART in 1983-2011

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    STUDY QUESTION: Do children, adolescents, and young adults born after ART, including IVF, ICSI and frozen-thawed embryo transfer (FET), have an increased risk of cancer compared with children born to subfertile couples not conceived by ART and children from the general population? SUMMARY ANSWER: After a median follow-up of 18 years, the overall cancer risk was not increased in children conceived by ART, but a slight risk increase was observed in children conceived after ICSI. WHAT IS KNOWN ALREADY: There is growing evidence that ART procedures could perturb epigenetic processes during the pre-implantation period and influence long-term health. Recent studies showed (non-)significantly increased cancer risks after ICSI and FET, but not after IVF. STUDY DESIGN, SIZE, DURATION: A nationwide historical cohort study with prospective follow-up was carried out, including all live-born offspring from women treated with ART between 1983 and 2011 and subfertile women not treated with ART in one of the 13 Dutch IVF clinics and two fertility centers. PARTICIPANTS/MATERIALS, SETTING, METHODS: Children were identified through the mothers' records in the Personal Records Database. Information on the conception method of each child was collected through the mother's medical record. In total, the cohort comprises 89 249 live-born children of subfertile couples, of whom 51 417 were conceived using ART and 37 832 were not (i.e. conceived naturally, through ovulation induction, or after IUI). Cancer incidence was ascertained through linkage with the Netherlands Cancer Registry for the period 1989-2019. Cancer risk in children conceived using ART was compared with risk in children born to subfertile couples but not conceived by ART (hazard ratio (HR)) and children from the general population (standardized incidence ratios (SIRs)). MAIN RESULTS AND THE ROLE OF CHANCE: In total, 358 cancers were observed after a median follow-up of 18 years. Overall cancer risk was not increased in children conceived using ART, when compared with the general population (SIR = 0.96, 95% CI = 0.81-1.12) or with children from subfertile couples not conceived by ART (HR = 1.06, 95% CI = 0.84-1.33). Compared with children from subfertile couples not conceived by ART, the use of IVF or FET was not associated with increased cancer risk, but ICSI was associated with a slight risk increase (HR = 1.58, 95% CI = 1.08-2.31). Risk of cancer after ART did not increase at older ages (≥18 years, HR = 1.26, 95% CI = 0.88-1.81) compared to cancer risk in children not conceived by ART. LIMITATIONS, REASONS FOR CAUTION: The observed increased risk among children conceived using ICSI must be interpreted with caution owing to the small number of cases. WIDER IMPLICATIONS OF THE FINDINGS: After a median follow-up of 18 years, children conceived using ART do not have an increased overall cancer risk. Many large studies with prolonged follow-up are needed to investigate cancer risk in (young) adults conceived by different types of ART. In addition, international pooling of studies is recommended to provide sufficient power to study risk of specific cancer sites after ART. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by The Dutch Cancer Society (NKI 2006-3631) that funded the OMEGA-women's cohort, Children Cancer Free (KIKA; 147) that funded the OMEGA-I-II offspring cohort. The OMEGA-III offspring cohort was supported by a Postdoc Stipend of Amsterdam Reproduction &amp; Development, and the Eunice Kennedy Shriver National Institute of Child Health &amp; Human Development of the National Institutes of Health under Award Number R01HD088393. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The authors declare no competing interests. TRIAL REGISTRATION NUMBER:N/A.</p

    Outcomes of open repair of postdissection abdominal aortic aneurysms

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    Background: Evidence to guide management of postdissection abdominal aortic aneurysms (PDAAA) is lacking. This study describes the outcomes of open repair of PDAAA. Methods: A retrospective cohort study was conducted of all consecutive patients treated with open repair for PDAAA after a Stanford type A or type B thoracic aortic dissection between January 2006 and December 2017 in two vascular referral centers. Preceding type B dissection treatment could include conservative or surgical management. Primary outcomes were 30-day mortality, complication rates, survival, and reintervention-free survival. Survival and reintervention-free survival were analyzed using the Kaplan-Meier method. Reintervention was defined as any endovascular or surgical intervention after the index procedure. Results: Included were 36 patients (27 men [75%]) with a median age of 64 years (range, 35-81 years). The 30-day mortality was 2.7%. The median follow-up was 16 months (range, 0-88 months). The postoperative course was uneventful in 21 patients (58%). The most frequent complications were postoperative bleeding requiring repeat laparotomy (n = 4), pneumonia (n = 3), congestive heart failure (n = 2), new-onset atrial fibrillation (n = 2), mesenteric ischemia requiring left hemicolectomy (n=1), and ischemic cerebrovascular accident (n = 1). Renal failure requiring hemodialysis developed in one patient. The overall survival at 1 year was 88.8%. Reintervention-free survival was 95.5% after 1 year and 88.6% after 2 years. Conclusions: Open repair of PDAAA can be performed with a low mortality rate and an acceptable complication rate, comparable with elective open repair of abdominal aortic aneurysms without dissection
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