75 research outputs found

    Physics of forebody flow control

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    Performance in the high angle of attack regime is required by many different types of aircraft. Military aircraft, such as fighters, utilize flight in this regime to improve maneuverability. Civilian aircraft, such as supersonic or hypersonic transports, will also need to operate in this regime during take off and landing, due to their small highly swept wings. Flight at high angles of attack is problematic due to the vortices being created on the nose of the aircraft. The vortices tend to become asymmetric and produce side forces. At the same time, the rudders are less effective because they are becoming immersed in the flow separating from the wings and fuselage. Consequently, the side force produced by the vortices on the nose tend to destabilize the aircraft. This situation may be corrected through the use of a forebody flow control system such as tangential slot blowing. In this concept, a jet is blown from the nose in an effort to alter the flow field around the nose and diminish the destabilizing side force. Alternately, the jet may be used to create a side force which could be used to augment the rudders. This would allow the size of the rudders to be decreased which would, in turn, diminish the cruise drag. Therefore, the use of a tangential slot blowing system has the potential for improving both the maneuver performance and the cruise performance of an aircraft. The present study was conducted to explore the physics of forebody flow control. The study consisted of two major thrusts: (1) exploration of forebody flow control with tangential slot blowing; (2) investigation of flow and field response to a general perturbation

    HIV-positive women have higher prevalence of comorbidites and anticholinergic burden. Assessment of the HIV positive population from Menorca (Balearic Islands)

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    Currently, the management of comorbidities and polypharmacy in HIV-infected patients requires a coordinated action, with special focus on gender differences. Observational, cross-sectional study was conducted to study the HIV population from Menorca (Illes Balears). Adult HIV-positive individuals on antiretroviral treatment attending the pharmacy service from Hospital Mateu Orfila (Menorca) were included. In a single visit, demographical and clinical characteristics, comorbidities and cotreatments were collected. Anticholinergic burden (Drug Burden Index, DBI), drug-to-drug interactions (BOT PLUS database) and symptoms associated with HIV treatment (HIV-SI index) were assessed. A total of 223 patients were included, 68.2% men, with a median age of 53.00 (44.50-58.00) years, median BMI of 24.07, 47.73% smokers and 9.90% drug consumers. Women had more advanced stages of the disease and significantly more symptoms (cough and anxiety) versus men (p = .033 and p = .048, respectively). Moreover higher exposures to anticholinergic drugs (DBI 0.51 vs. 0.27) were reported, together with more frequency of drug-to-drug interactions (57.7% vs. 37.5%; p = .005) that increased with age. Red interactions were more frequently reported in PI (2.69%), NNRTIs (1.92%) and booster drugs (1.92%). These results support the need to implement specific measures for the management of HIV-infected women and tools to assess polypharmacy and risk of drug-to-drug interactions. Keywords: HIV infection; anticholinergic burden; anxiety; comorbidities; drug-to-drug interactions; women

    Magnetic behavior of heterometallic wheels having a [MnIV6M2O9]10+ core with M = Ca2+ and Sr2+

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    Two new heterometallic MnIV−M2+ compounds with formula [Mn6M2O9(4-tBuC6H4COO)10(4-tBuC6H4COOH)5] (M = Ca2+ (1), Sr2+ (2)) have been crystallized. The core of both compounds consists of a planar Mn6 ring, where the MnIV ions are alternatively bridged by (μ3-O)2(μ-RCOO) and (μ4-O)(μ-RCOO)2 ligands, and the two alkaline earth ions are located to both sides of the wheel, linked to the oxo bridges, generating three fused [Mn2M2O4]4+ cuboids. These compounds show a net antiferromagnetic behavior, more important for 2 (Sr2+) than for 1 (Ca2+). The fitting of the experimental data was performed with the support of DFT calculations, considering four different exchange pathways: two between adjacent MnIV ions (J1 and J2) and two between nonadjacent MnIV ions (J3 and J4). The results of the analysis show that J1 and J2 are of the opposite sign, the ferromagnetic contribution corresponding to the [Mn2(μ4- O)(μ-RCOO)2]4+ unit (J2). The influence of the M2+ ions in the magnetic behavior is analyzed for 1 and 2 and for three hypothetical models with the structural parameters of 1 containing Mg2+, Sr2+ or without the M2+ ions. In spite of the diamagnetic character of the alkaline earth ions, their influence on the magnetic behavior has been evidenced and correlated with their polarizing effect. Moreover, the magnetic interactions between nonadjacent ions are non-negligible

    Azimuthal distinguishability of entangled photons generated in spontaneous parametric down-conversion

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    We experimentally demonstrate that paired photons generated in different sections of a down-conversion cone, when some of the interacting waves show Poynting vector walk-off, carry different spatial correlations, and therefore a different degree of spatial entanglement. This is shown to be in agreement with theoretical results. We also discuss how this azimuthal distinguishing information of the down-conversion cone is relevant for the implementation of quantum sources aimed at the generation of entanglement in other degrees of freedom, such as polarization.Comment: 7 pages, 5 figures, submitted to Opt. Expres

    Long-term bio-cultural heritage: exploring the intermediate disturbance hypothesis in agro-ecological landscapes (Mallorca, c. 1850-2012)

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    We applied an intermediate disturbance-complexity approach to the land-use change of cultural landscapes in the island of Mallorca from c. 1850 to the present, which accounts for the joint behaviour of human appropriation of photosynthetic capacity used as a measure of disturbance, and a selection of land metrics at different spatial scales that account for ecological functionality as a proxy of biodiversity. We also delved deeper into local land-use changes in order to identify the main socioeconomic drivers and ruling agencies at stake. A second degree polynomial regression was obtained linking socio-metabolic disturbance and landscape ecological functioning (jointly assessing landscape patterns and processes). The results confirm our intermediate disturbance-complexity hypothesis by showing a hump-shaped relationship where the highest level of landscape complexity (heterogeneity connectivity) is attained when disturbance peaks at 50 60 %. The study proves the usefulness of transferring the concept of intermediate disturbance to Mediterranean cultural landscapes, and suggests that the conservation of heterogeneous and well connected land-use mosaics with a positive interplay between intermediate level of farming disturbances and land-cover complexity endowed with a rich bio-cultural heritage will preserve a wildlife-friendly agro-ecological matrix that is likely to house high biodiversity

    Highly sensitive MLH1 methylation analysis in blood identifies a cancer patient with low-level mosaic MLH1 epimutation

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    Constitutional MLH1 methylation (epimutation) is a rare cause of Lynch syndrome. Low-level methylation (<= 10%) has occasionally been described. This study aimed to identify low-level constitutional MLH1 epimutations and determine its causal role in patients with MLH1-hypermethylated colorectal cancer. Eighteen patients with MLH1-hypermethylated colorectal tumors in whom MLH1 methylation was previously undetected in blood by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) were screened for MLH1 methylation using highly sensitive MS-melting curve analysis (MS-MCA). Constitutional methylation was characterized by different approaches. MS-MCA identified one patient (5.6%) with low-level MLH1 methylation ( 1%) in blood and other normal tissues, which was confirmed by clonal bisulfite sequencing in blood. The patient had developed three clonally related gastrointestinal MLH1-methylated tumor lesions at 22, 24, and 25 years of age. The methylated region in normal tissues overlapped with that reported for other carriers of constitutional MLH1 epimutations. Low-level MLH1 methylation and reduced allelic expression were linked to the same genetic haplotype, whereas the opposite allele was lost in patient's tumors. Mutation screening of MLH1 and other hereditary cancer genes was negative. Herein, a highly sensitive MS-MCA-based approach has demonstrated its utility for the identification of low-level constitutional MLH1 epigenetic mosaicism. The eventual identification and characterization of additional cases will be critical to ascertain the cancer risks associated with constitutional MLH1 epigenetic mosaicism

    Joint Observation of the Galactic Center with MAGIC and CTA-LST-1

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    MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs), designed to detect very-high-energy gamma rays, and is operating in stereoscopic mode since 2009 at the Observatorio del Roque de Los Muchachos in La Palma, Spain. In 2018, the prototype IACT of the Large-Sized Telescope (LST-1) for the Cherenkov Telescope Array, a next-generation ground-based gamma-ray observatory, was inaugurated at the same site, at a distance of approximately 100 meters from the MAGIC telescopes. Using joint observations between MAGIC and LST-1, we developed a dedicated analysis pipeline and established the threefold telescope system via software, achieving the highest sensitivity in the northern hemisphere. Based on this enhanced performance, MAGIC and LST-1 have been jointly and regularly observing the Galactic Center, a region of paramount importance and complexity for IACTs. In particular, the gamma-ray emission from the dynamical center of the Milky Way is under debate. Although previous measurements suggested that a supermassive black hole Sagittarius A* plays a primary role, its radiation mechanism remains unclear, mainly due to limited angular resolution and sensitivity. The enhanced sensitivity in our novel approach is thus expected to provide new insights into the question. We here present the current status of the data analysis for the Galactic Center joint MAGIC and LST-1 observations

    Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

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    Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

    CALYPSO 2019 Cruise Report: field campaign in the Mediterranean

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    This cruise aimed to identify transport pathways from the surface into the interior ocean during the late winter in the Alborán sea between the Strait of Gibraltar (5°40’W) and the prime meridian. Theory and previous observations indicated that these pathways likely originated at strong fronts, such as the one that separates salty Mediterranean water and the fresher water in owing from the Atlantic. Our goal was to map such pathways and quantify their transport. Since the outcropping isopycnals at the front extend to the deepest depths during the late winter, we planned the cruise at the end of the Spring, prior to the onset of thermal stratification of the surface mixed layer.Funding was provided by the Office of Naval Research under Contract No. N000141613130
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