Milky Way dwarf spheroidal galaxies (dSphs) are among the best candidates to search for signals of dark matter annihilation with Imaging Atmospheric Cherenkov Telescopes, given their high ...mass-to-light ratios and the fact that they are free of astrophysical gamma-ray emitting sources. Since 2011, MAGIC has performed a multi-year observation program in search for Weakly Interacting Massive Particles (WIMPs) in dSphs. Results on the observations of Segue 1 and Ursa Major II dSphs have already been published and include some of the most stringent upper limits (ULs) on the velocity-averaged cross-section 〈σannv〉 of WIMP annihilation from observations of dSphs. In this work, we report on the analyses of 52.1h of data of Draco dSph and 49.5h of Coma Berenices dSph observed with the MAGIC telescopes in 2018 and in 2019 respectively. No hint of a signal has been detected from either of these targets and new constraints on the 〈σannv〉 of WIMP candidates have been derived. In order to improve the sensitivity of the search and reduce the effect of the systematic uncertainties due to the J-factor estimates, we have combined the data of all dSphs observed with the MAGIC telescopes. Using 354.3h of dSphs good quality data, 95% CL ULs on 〈σannv〉 have been obtained for 9 annihilation channels. For most of the channels, these results reach values of the order of 10−24cm3/s at ∼1TeV and are the most stringent limits obtained with the MAGIC telescopes so far.
ABSTRACT
We investigate the physical nature and origin of the gamma-ray emission from the extended source HESS J1841−055 observed at TeV and GeV energies. We observed HESS J1841−055 at TeV energies ...for a total effective time of 43 h with the MAGIC telescopes, in 2012 and 2013. Additionally, we analysed the GeV counterpart making use of about 10 yr of Fermi-LAT data. Using both Fermi-LAT and MAGIC, we study both the spectral and energy-dependent morphology of the source for almost four decades of energy. The origin of the gamma-ray emission from this region is investigated using multiwaveband information on sources present in this region, suggested to be associated with this unidentified gamma-ray source. We find that the extended emission at GeV–TeV energies is best described by more than one source model. We also perform the first energy-dependent analysis of the HESS J1841−055 region at GeV–TeV. We find that the emission at lower energies comes from a diffuse or extended component, while the major contribution of gamma rays above 1 TeV arises from the southern part of the source. Moreover, we find that a significant curvature is present in the combined observed spectrum of MAGIC and Fermi-LAT. The first multiwavelength spectral energy distribution of this unidentified source shows that the emission at GeV–TeV energies can be well explained with both leptonic and hadronic models. For the leptonic scenario, bremsstrahlung is the dominant emission compared to inverse Compton. On the other hand, for the hadronic model, gamma-ray resulting from the decay of neutral pions (π0) can explain the observed spectrum. The presence of dense molecular clouds overlapping with HESS J1841−055 makes both bremsstrahlung and π0-decay processes the dominant emission mechanisms for the source.
We present the first results from very-high-energy observations of the dwarf spheroidal satellite candidate Triangulum II with the MAGIC telescopes from 62.4 h of good-quality data taken between ...August 2016 and August 2017. We find no gamma-ray excess in the direction of Triangulum II, and upper limits on both the differential and integral gamma-ray flux are presented. Currently, the kinematics of Triangulum II are affected by large uncertainties leading to a bias in the determination of the properties of its dark matter halo. Using a scaling relation between the annihilation J-factor and heliocentric distance of well-known dwarf spheroidal galaxies, we estimate an annihilation J-factor for Triangulum II for WIMP dark matter of logJann(0.5°)∕GeV2cm−5=19.35±0.37. We also derive a dark matter density profile for the object relying on results from resolved simulations of Milky Way sized dark matter halos. We obtain 95% confidence-level limits on the thermally averaged annihilation cross section for WIMP annihilation into various Standard Model channels. The most stringent limits are obtained in the τ−τ+ final state, where a cross section for annihilation down to 〈σannv〉=3.05×10−24 cm3 s−1 is excluded.
The high affinity IgE Fc receptor (Fc epsilon RI), found on mast cells and basophils, is a tetrameric receptor complex. The
extracellular portion of the Fc epsilon RI alpha subunit consists of two ...immunoglobulin-like domains and binds IgE in the
absence of the other subunits. To localize the high affinity IgE binding site within the Fc epsilon RI alpha subunit, we generated
a series of chimeric receptor constructs where one of the two immunoglobulin-like domains was either deleted or substituted
with those from the human Fc gamma RIIIA alpha or the rat Fc epsilon RI alpha subunit. The chimeric receptors were monitored
for their capacity to bind human and rat IgE, and their reactivity with different antireceptor antibodies. Domain I substitutions
maintained high affinity human IgE binding. Domain II substitutions resulted in a total loss of both human and rat IgE binding.
Single-domain alpha subunits could not bind IgE, suggesting that both extracellular domains are required for proper protein
folding or IgE binding. To further localize the IgE binding sites, homolog-scanning mutagenesis was performed. At least three
independent regions of domain II encompassing residues 118-129, 136-150, and 148-162 were required for IgE binding. Our results
suggest that domain II of the human Fc epsilon RI alpha confers most of the important contributions to the binding of the
human IgE Fc molecule, whereas domain I of the rat Fc epsilon RI alpha makes important contributions to the binding of rat
IgE.
Summary Resistant hypertension is defined as blood pressure above goal despite adherence to a combination of at least three optimally dosed antihypertensive medications, one of which is a diuretic. ...Chronic kidney disease is the most frequent of several patient factors or comorbidities associated with resistant hypertension. The prevalence of resistant hypertension is increased in patients with chronic kidney disease, while chronic kidney disease is associated with an impaired prognosis in patients with resistant hypertension. Recommended low-salt diet and triple antihypertensive drug regimens that include a diuretic, should be complemented by the sequential addition of other antihypertensive drugs. New therapeutic innovations for resistant hypertension, such as renal denervation and carotid barostimulation, are under investigation especially in patients with advanced chronic kidney disease. We discuss resistant hypertension in chronic kidney disease stages 3–5 (ie, patients with an estimated glomerular filtration rate below 60 mL/min per 1·73 m2 and not on dialysis), in terms of worldwide epidemiology, outcomes, causes and pathophysiology, evidence-based treatment, and a call for action.
Objectives This study sought to investigate clinical and echocardiographic correlates of the lung comets score. Background Early detection of pulmonary congestion is a fundamental goal for the ...prevention of congestive heart failure in high-risk patients. Methods We undertook an inclusive survey by a validated ultrasound (US) technique in a hemodialysis center to estimate the prevalence of pulmonary congestion and its reversibility after dialysis in a population of 75 hemodialysis patients. Results Chest US examinations were successfully completed in all patients (N = 75). Before dialysis, 47 patients (63%) exhibited moderate to severe lung congestion. This alteration was commonly observed in patients with heart failure but also in the majority of asymptomatic (32 of 56, 57%) and normohydrated (19 of 38, 50%) patients. Lung water excess was unrelated with hydration status but it was strongly associated with New York Heart Association functional class (p < 0.0001), left ventricular ejection fraction (r = –0.55, p < 0.001), early filling to early diastolic mitral annular velocity (r = 0.48, p < 0.001), left atrial volume (r = 0.39, p = 0.001), and pulmonary pressure (r = 0.36, p = 0.002). Lung water reduced after dialysis, but 23 patients (31%) still had pulmonary congestion of moderate to severe degree. Lung water after dialysis maintained a strong association with left ventricular ejection fraction (r = –0.59, p < 0.001), left atrial volume (r = 0.30, p = 0.01), and pulmonary pressure (r = 0.32, p = 0.006) denoting the critical role of cardiac performance in the control of this water compartment in end-stage renal disease. In a multiple regression model including traditional and nontraditional risk factors only left ventricular ejection fraction maintained an independent link with lung water excess (beta = –0.61, p < 0.001). Repeatability studies of the chest US technique (Bland-Altman plots) showed good interobserver and inter-US probes reproducibility. Conclusions Pulmonary congestion is highly prevalent in symptomatic (New York Heart Association functional class III to IV) and asymptomatic dialysis patients. Chest ultrasound is a reliable technique that detects pulmonary congestion at a pre-clinical stage in end-stage renal disease.
The Cherenkov Telescope Array (CTA) will observe the very high energy gamma-ray sky (20 GeV - 300 TeV) with unprecedented performance in terms of sensitivity, angular and energy resolution. CTA will ...be deployed in two sites, one in each hemisphere for full-sky coverage. In each site four Large Size Telescopes (LSTs) of 23 m diameter dish will cover the lowest energy range (20 GeV - 200 GeV). In Autumn 2018 the first LST has been inaugurated in the Canary Island of La Palma and has entered the commissioning phase. Its focal plane is composed by 265 modules, each one hosting 7 photomultiplier tubes (PMTs) with 1.5 inches diameter pupil.Thanks to their features, in particular their high photon detection efficiency, tolerance to high illumination level and small pixel size, Silicon Photomultipliers (SiPMs) are already the baseline photosensors for the dual mirror telescopes and the single mirror small telescopes of CTA. On the other hand the application of such devices in focal planes with larger plate scales is still challenging, but could provide improvements in the performance of the telescopes.For this reason we are developing a module for the LST camera, with each PMT replaced by a SiPM array whose outputs are summed into a single signal, read by the standard LST electronics. We present here the status of the project and the preliminary measurements obtained with our prototype.
Anorthite‐glass films were grown on basal Al2O3 substrates using pulsed‐laser deposition. The substrates were cleaned and annealed in air at 1400°C to produce crystallographically flat (0001) ...terraces. The films were deposited in an oxidizing environment. X‐ray microanalysis confirmed the composition of the glass films to be close to that of anorthite (CaO·Al2O3·2SiO2). Although anorthite usually has triclinic symmetry, subsequent crystallization of these films in air at 1200°C resulted in the formation of pseudo‐orthorhombic CaAl2Si2O8 (o‐anorthite), a known metastable form of the mineral. Microstructural characterization was performed using visible‐light microscopy, scanning electron microscopy, and transmission electron microscopy. The films dewetted the substrate either before or after crystallization to form o‐anorthite islands which had strong orientation relationships to the Al2O3 substrate. The epitaxy of the o‐anorthite islands was accompanied by a small lattice mismatch parallel to the substrate plane. The formation of three orientational variants is consistent with the symmetry of the basal Al2O3 surface. The dislocation network observed at the o‐anorthite/Al2O3 interface indicates that nucleation and growth of the anorthite occurs directly on the substrate surface without an intervening interfacial amorphous layer. The study of anorthite‐glass films is important because they are present in liquid‐phase‐sintered Al2O3, and may be devitrified by postsintering heat treatments.
Silicate-glass films were grown by pulsed-laser deposition on single-crystal, basal-plane Al2O3 substrates which had been pre-thinned to electron transparency. Experiments were then performed at high ...temperature in the TEM, which allowed direct observation and video-recording of the crystallization process. The epitactic growth of pseudo-orthorhombic anorthite (CaAl2Si2O8) and grossular (Ca3Al2Si3O12) on the basal Al2O3 surface was observed, emphasizing the role of the substrate as a “seed” for glass devitrification. The grossular crystals nucleated and grew at random on the substrate surface. In contrast, the anorthite crystals showed preferential nucleation at defect sites in the as-deposited glass film. Nucleation was followed by lateral growth along the substrate surface radiating away from the defect sites. Rotational variants for the silicate crystals were found in both cases, owing to the three-fold symmetry of the substrate. The simultaneous growth of these rotational variants on the substrate surface caused the formation of high-symmetry grain boundaries within the silicate film. In the anorthite film, these grain boundaries were often faceted parallel to low-index planes in one or both grains.
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