Inverse Compton X-rays from relativistic flare electrons and positrons

<p><b>Context:</b> In solar flares, inverse Compton scattering (ICS) of photospheric photons might give rise to detectable hard X-ray photon fluxes from the corona where ambient densities are too low for significant bremsstrahlung or recombination. γ-ray lines and continuum in some large flares imply the presence of the necessary ~100 MeV electrons and positrons, the latter as by-products of GeV energy ions. Recent observations of coronal hard X-ray sources in particular prompt us to reconsider here the possible contribution of ICS.</p> <p><b>Aims:</b> We aim to evaluate the ICS X-ray fluxes to be expected from prescribed populations of relativistic electrons and positrons in the solar corona. The ultimate aim is to determine if ICS coronal X-ray sources might offer a new diagnostic window on relativistic electrons and ions in flares.</p> <p><b>Methods:</b> We use the complete formalism of ICS to calculate X-ray fluxes from possible populations of flare primary electrons and secondary positrons, paying attention to the incident photon angular distribution near the solar surface and thus improving on the assumption of isotropy made in previous solar discussions.</p> <p><b>Results:</b> Both primary electrons and secondary positrons produce very hard ICS X-ray spectra. The anisotropic primary radiation field results in pronounced centre-to-limb variation in predicted fluxes and spectra, with the most intense spectra, extending to the highest photon energies, expected from limb flares. Acceptable numbers of electrons or positrons could account for RHESSI coronal X/γ-ray sources.</p> <p><b>Conclusions:</b> Some coronal X-ray sources at least might be interpreted in terms of ICS by relativistic electrons or positrons, particularly when sources appear at such low ambient densities that bremsstrahlung appears implausible.</p&gt

Imanes & armadilhas: envolvimento de munícipes açorianos no controlo de uma praga urbana

Fórum Internacional de Pedagogia II (FIPED) - "Investigar é conhecer". Universidade dos Açores, Angra do Heroísmo, Portugal, 13 e 14 de Abril de 2012.A Cryptotermes brevis é das pragas de insetos que maiores danos causam ao ser capaz de consumir toda a infraestrutura em madeira de uma habitação. $120 milhões são gastos anualmente nos EUA para o seu controlo e inumeráveis somas no resto do globo. Nos Açores, 17 freguesias de 6 ilhas estão delimitadas como áreas de risco de infestação e desconhece-se a situação em muitos locais de várias ilhas

Deficiência de glicose-6-fosfato desidrogenase eritrocitária em recém-nascidos do sexo masculino e sua relação com a icterícia neonatal

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the commonest red cell enzymopathy in humans, has an X-linked inheritance. The major clinical manifestations are drug induced hemolytic anemia, neonatal jaundice and chronic nonspherocytic hemolytic anemia. The incidence of neonatal hyperbilirubinemia is much greater in G6PD-deficient neonates than babies without this deficiency. The aim of this study was to ascertain the presence of neonatal jaundice in erythrocyte G6PD-deficient male newborns. Samples of umbilical cord blood from a total of 204 male newborns of the Januário Cicco School Maternity located in Natal, Rio Grande do Norte, Brazil were analyzed. The G6PD deficiency was identified by the methemoglobin reduction test (Brewer's test). The deficiency was confirmed by quantitative spectrophotometric assay for enzyme activity and cellulose acetate electrophoresis was used to identify the G6PD variant. Eight newborns were found to be G6PD deficient with four of them exhibiting jaundice during the first 48 hours after birth with bilirubin levels higher than 10 mg/dL. All deficient individuals presented the G6PD A- variant at electrophoresis. Our findings confirmed the association between G6PD deficiency and neonatal jaundice. Hence, early diagnosis of the deficiency at birth is essential to control the appearance of jaundice and to prevent the exposure of these newborns to known hemolytic agents.A deficiência de glicose-6-fosfato desidrogenase (G6PD) é a anormalidade enzimática hereditária mais frequente. É transmitida como caráter recessivo ligado ao cromossomo X e as principais manifestações clínicas são hemólise induzida por fármacos, icterícia neonatal e anemia hemolítica não esferocítica. O objetivo do estudo foi determinar a presença de icterícia neonatal em recém-nascidos do sexo masculino deficientes de glicose-6-fosfato desidrogenase. Foram analisadas 204 amostras de sangue umbilical de recém-nascidos do sexo masculino provenientes da Maternidade Escola Januário Cicco em Natal, Rio Grande do Norte. A deficiência da glicose-6-fosfato desidrogenase foi determinada através do método qualitativo da redução da metahemoglobina (teste de Brewer) e confirmada mediante determinação espectrofotométrica quantitativa da atividade da G6PD e pela eletroforese da enzima em acetato de celulose. Oito recém-nascidos apresentaram deficiência da G6PD, e quatro deles exibiram icterícia nas primeiras 48 horas depois do nascimento, com valores de bilirrubina maiores de 10 mg/dL. Todos os deficientes apresentaram a variante A-. Os dados encontrados confirmam a associação da deficiência da G6PD e a icterícia neonatal. Assim sendo, o diagnóstico precoce da deficiência logo após o nascimento é essencial ao controle do aparecimento da icterícia e para evitar o contato destes recém-nascidos com conhecidos agentes hemolíticos

Rapid Submillimeter Brightenings Associated with a Large Solar Flare

We present high time resolution observations of Active Region 8910 obtained simultaneously at 212 and 405 GHz during a large Hα flare, which produced a soft X-ray class X1.1 event. Data were obtained with the new solar submillimeter telescope recently installed at the El Leoncito Observatory to explore this poorly known part of the solar emission spectrum. A small slow submillimeter enhancement (≤300 sfu) was associated to bulk emissions at X-rays, Hα, and microwaves. The event exhibited numerous submillimeter-wave 100-300 ms duration spikes, the larger ones with fluxes on the order of 220 and 500 sfu (±20%) at 212 and 405 GHz, respectively. A dramatic increase in the incidence rate of submillimeter spikes sets in as a new large loop system appears in AR 8910, and X-ray emission increases nearly 1 hr before the large flare. The brightening incidence rate (~20 per minute) correlates well with the large flare light curves at X-rays and Hα. The submillimeter spikes may be associated to microflares, waves, or quakes in flaring active regions.Facultad de Ciencias Astronómicas y Geofísica

Rapid Submillimeter Brightenings Associated with a Large Solar Flare

We present high time resolution observations of Active Region 8910 obtained simultaneously at 212 and 405 GHz during a large Hα flare, which produced a soft X-ray class X1.1 event. Data were obtained with the new solar submillimeter telescope recently installed at the El Leoncito Observatory to explore this poorly known part of the solar emission spectrum. A small slow submillimeter enhancement (≤300 sfu) was associated to bulk emissions at X-rays, Hα, and microwaves. The event exhibited numerous submillimeter-wave 100-300 ms duration spikes, the larger ones with fluxes on the order of 220 and 500 sfu (±20%) at 212 and 405 GHz, respectively. A dramatic increase in the incidence rate of submillimeter spikes sets in as a new large loop system appears in AR 8910, and X-ray emission increases nearly 1 hr before the large flare. The brightening incidence rate (~20 per minute) correlates well with the large flare light curves at X-rays and Hα. The submillimeter spikes may be associated to microflares, waves, or quakes in flaring active regions.Fil: Kaufmann, Pierre. Universidade Presbiteriana Mackenzie; BrasilFil: Raulin, J. P. Universidade Presbiteriana Mackenzie; BrasilFil: Correia, E.. Universidade Presbiteriana Mackenzie; BrasilFil: Costa, J. E. R.. Universidade Presbiteriana Mackenzie; BrasilFil: Giménez de Castro, C. G.. Universidade Presbiteriana Mackenzie; BrasilFil: Silva, A. V. R.. Universidade Presbiteriana Mackenzie; BrasilFil: Levato, Orlando Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "el Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "el Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "el Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "el Leoncito"; ArgentinaFil: Rovira, Marta Graciela. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Fernández Borda, R.. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Bauer, O. H.. Max PlanckInstitut fur extraterrestrische Physik,; Alemani

Randomised controlled trial comparing efficacy and safety of high versus low Low-Molecular Weight Heparin dosages in hospitalized patients with severe COVID-19 pneumonia and coagulopathy not requiring invasive mechanical ventilation (COVID-19 HD): a structured summary of a study protocol.

To assess whether high doses of Low Molecular Weight Heparin (LMWH) (i.e. Enoxaparin 70 IU/kg twice daily) compared to standard prophylactic dose (i.e., Enoxaparin 4000 IU once day), in hospitalized patients with COVID19 not requiring Invasive Mechanical Ventilation [IMV], are: a)more effective in preventing clinical worsening, defined as the occurrence of at least one of the following events, whichever comes first: 1.Death2.Acute Myocardial Infarction [AMI]3.Objectively confirmed, symptomatic arterial or venous thromboembolism [TE]4.Need of either: a.Continuous Positive Airway Pressure (Cpap) or Non-Invasive Ventilation (NIV) orb.IMV in patients who at randomisation were receiving standard oxygen therapy5.IMV in patients who at randomisation were receiving non-invasive mechanical ventilationb)Similar in terms of major bleeding risk TRIAL DESIGN: Multicentre, randomised controlled, superiority, open label, parallel group, two arms (1:1 ratio), in-hospital study

Fermi observations of high-energy gamma-ray emission from GRB 090217A

The Fermi observatory is advancing our knowledge of Gamma-Ray Bursts (GRBs) through pioneering observations at high energies, covering more than 7 decades in energy with the two on-board detectors, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). Here we report on the observation of the long GRB 090217A which triggered the GBM and has been detected by the LAT with a significance greater than 9 sigma. We present the GBM and LAT observations and on-ground analyses, including the time-resolved spectra and the study of the temporal profile from 8 keV up to 1 GeV. All spectra are well reproduced by a Band model. We compare these observations to the first two LAT-detected, long bursts GRB 080825C and GRB 080916C. These bursts were found to have time-dependent spectra and exhibited a delayed onset of the high-energy emission, which are not observed in the case of GRB 090217A. We discuss some theoretical implications for the high-energy emission of GRBs.Comment: 17 pages, 4 figures. Contact Authors: Fred, Piron; Sara, Cutini; Andreas, von Kienli