Objective One of the main problems of lung transplantation is the shortage of organs as well as reduced survival rates. In the absence of an international standardized model for lung donor-recipient ...allocation, we set out to develop such a model based on the characteristics of past experiences with lung donors and recipients with the aim of improving the outcomes of the entire transplantation process. Methods This was a retrospective analysis of 404 lung transplants carried out at the Reina Sofía University Hospital (Córdoba, Spain) over 23 years. We analyzed various clinical variables obtained via our experience of clinical practice in the donation and transplantation process. These were used to create various classification models, including classical statistical methods and also incorporating newer machine-learning approaches. Results The proposed model represents a powerful tool for donor-recipient matching, which in this current work, exceeded the capacity of classical statistical methods. The variables that predicted an increase in the probability of survival were: higher pre-transplant and post-transplant functional vital capacity (FVC), lower pre-transplant carbon dioxide (PCO2) pressure, lower donor mechanical ventilation, and shorter ischemia time. The variables that negatively influenced transplant survival were low forced expiratory volume in the first second (FEV1) pre-transplant, lower arterial oxygen pressure (PaO2)/fraction of inspired oxygen (FiO2) ratio, bilobar transplant, elderly recipient and donor, donor-recipient graft disproportion requiring a surgical reduction (Tailor), type of combined transplant, need for cardiopulmonary bypass during the surgery, death of the donor due to head trauma, hospitalization status before surgery, and female and male recipient donor sex. Conclusions These results show the difficulty of the problem which required the introduction of other variables into the analysis. The combination of classical statistical methods and machine learning can support decision-making about the compatibility between donors and recipients. This helps to facilitate reliable prediction and to optimize the grafts for transplantation, thereby improving the transplanted patient survival rate.
The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report ...the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera–electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera–electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.
We present the first catalog of TeV gamma-ray sources realized with data from the newly completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV ...telescope currently in operation, with a one-year survey sensitivity of ∼5%-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma-ray energies between hundreds of GeV and tens of TeV. HAWC is located in Mexico, at a latitude of 19° N, and was completed in 2015 March. Here, we present the 2HWC catalog, which is the result of the first source search performed with the complete HAWC detector. Realized with 507 days of data, it represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected number of false detections of 0.5 due to background fluctuation. Out of these sources, 19 are new sources that are not associated with previously known TeV sources (association criteria: <0 5 away). The source list, including the position measurement, spectrum measurement, and uncertainties, is reported, then each source is briefly discussed. Of the 2HWC associated sources, 10 are reported in TeVCat as PWN or SNR: 2 as blazars and the remaining eight as unidentified.
The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV ...instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field of view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above ∼1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form . The data is well fitted with values of = 2.63 0.03, β = 0.15 0.03, and when E0 is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be 50% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC all-sky survey will be the deepest survey of the northern sky ever conducted in the multi-TeV band.
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•Vitamin D supplementation in asthmatic patients causes a decrease in colonization by pathogenic bacteria in airway.•Vitamin D supplementation is associated with a increase of seric ...levels of IL-10 and IFNγ.•Decrease of pathogenic bacteria in airway is associated with the expression of cathelicidin LL-37.
Vitamin D is a molecule that modulates the immune response and shows anti-inflammatory effects that are beneficial for the control of chronic diseases such as asthma. The trial aim was to explore the effect of vitamin D supplementation on the colonization of pathogenic bacteria in the upper respiratory tract of allergic asthmatic patients.
This study was conducted in 86 patients between 18 and 50 years of age who were randomly divided into two groups. Both groups received the treatment recommended by the Global Initiative for Asthma (GINA). One group also received calcitriol (1,25-(OH)2D3), and the other group received a placebo. At baseline and 6 months, skin prick tests were conducted, pharyngeal bacterial cultures were performed, and cathelicidin LL-37 was measured in sputum. Serum levels of IgE, eosinophils, IL-5, IL-9, IL-10, IL-13, and IFNγ were quantified at the beginning and the end of the study.
Serum levels of IL-10 and IFNγ increased significantly in the group of patients with vitamin D supplementation, while IL-5, IL-9, and IL-13 decreased significantly. At the end of the trial, IgE and eosinophil levels significantly decreased but allergen sensitivity did not show any changes from baseline. Respiratory infections were drastically reduced, and this decrease was related to the number of patients who had high serum levels of IL-10 and IFNγ and expressed LL-37 in their sputum.
Treatment of asthma patients with vitamin D reduced respiratory infections, and this effect was related to the increase of cathelicidin LL-37.
Deep neural networks are a powerful technique that have found ample applications in several branches of physics. In this work, we apply deep neural networks to a specific problem of cosmic ray ...physics: the estimation of the muon content of extensive air showers when measured at the ground. As a working case, we explore the performance of a deep neural network applied to large sets of simulated signals recorded for the water-Cherenkov detectors of the Surface Detector of the Pierre Auger Observatory. The inner structure of the neural network is optimized through the use of genetic algorithms. To obtain a prediction of the recorded muon signal in each individual detector, we train neural networks with a mixed sample of simulated events that contain light, intermediate and heavy nuclei. When true and predicted signals are compared at detector level, the primary values of the Pearson correlation coefficients are above 95%. The relative errors of the predicted muon signals are below 10% and do not depend on the event energy, zenith angle, total signal size, distance range or the hadronic model used to generate the events.
We report on anomalously long duration (2 ms) count rate bursts following the impact of cosmic ray showers near a 7.62 cm x⊘7.62 cm LaBr3 scintillation detector at the High Altitude Water Cherenkov ...array in Mexico, previously described by Stenkin et al. (2001), and termed “neutron bursts.” The largest burst produced 198 counts within 2 ms in our LaBr3 detector. We simulate the neutron burst albedo flux (that is, secondary emissions from an extensive air shower core impacting the ground), and show that (1) the characteristic spectra and count rates are well explained by neutron absorption in the ground and (2) any cosmic ray secondary that produces neutrons, either through hadron inelastic collisions, or photoneutron production by gamma‐rays, produces the same characteristic spectra. This implies that other natural phenomena that produce downward beams of gamma‐rays, like Terrestrial gamma ray flashes, should produce a similar “neutron burst” signature from the photoneutron reactions occurring in the soil.
Plain Language Summary
When very large cosmic ray showers (CRS) impact the ground, neutrons are produced in the soil that will rattle around until they become captured by soil particles and release energetic gamma‐rays. This produces a slow explosion of particles emanating from the ground following a CRS impact, and is termed a 'neutron burst'. We present recent observations of neutron bursts from a hand held sized gamma‐ray detector at the High Altitude Water Cherenkov (HAWC) array in Mexico, that exhibit interesting spectral features (the presence of positron annihilation), and an interesting time structure (hundreds of counts within a few ms). Our simulations indicate that Terrestrial gamma‐ray flashes (TGFs, bursts of gamma‐rays associated with lightning) should also produce these neutron bursts. An implication of this work is that existing deployments of ground based TGF instruments, comprised of small gamma‐ray detectors, can additionally be used to observe signatures of large cosmic ray showers on clear days.
Key Points
We report on fairweather count rate bursts with 2 ms duration following the impact of a large cosmic ray shower near a small scintillation detector at HAWC
Simulations show that the spectra and decay time can be produced by either hadronic interactions, or photoneutron reactions from gamma‐rays
These results imply that downward TGFs could produce a similar delayed neutron signature in the soil near ground based detectors
Abstract Galactic cosmic rays (GCRs) are charged particles that reach the heliosphere almost isotropically in a wide energy range. In the inner heliosphere, the GCR flux is modulated by solar ...activity so that only energetic GCRs reach the lower layers of the solar atmosphere. In this work, we propose that high-energy GCRs can be used to explore the solar magnetic fields at low coronal altitudes. We used GCR data collected by the High-Altitude Water Cherenkov observatory to construct maps of GCR flux coming from the Sun’s sky direction and studied the observed GCR deficit, known as Sun shadow (SS), over a 6 yr period (2016–2021) with a time cadence of 27.3 days. We confirm that the SS is correlated with sunspot number, but we focus on the relationship between the photospheric solar magnetic field measured at different heliolatitudes and the relative GCR deficit at different energies. We found a linear relationship between the relative deficit of GCRs represented by the depth of the SS and the solar magnetic field. This relationship is evident in the observed energy range of 2.5–226 TeV, but is strongest in the range of 12.4 33.4 TeV, which implies that this is the best energy range to study the evolution of magnetic fields in the low solar atmosphere.
We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov Observatory, a wide field-of-view observatory capable of detecting ...gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons.
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field of view observatory sensitive to 500 GeV-100 TeV gamma-rays and cosmic rays. It can also perform diverse indirect ...searches for dark matter annihilation and decay. Among the most promising targets for the indirect detection of dark matter are dwarf spheroidal galaxies. These objects are expected to have few astrophysical sources of gamma-rays but high dark matter content, making them ideal candidates for an indirect dark matter detection with gamma-rays. Here we present individual limits on the annihilation cross section and decay lifetime for 15 dwarf spheroidal galaxies within the field of view, as well as their combined limit. These are the first limits on the annihilation cross section and decay lifetime using data collected with HAWC. We also present the HAWC flux upper limits of the 15 dwarf spheroidal galaxies in half-decade energy bins.
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