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A cornerstone of Einstein's special relativity is Lorentz invariance-the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l(Planck) approximately 1.62 x 10(-33) cm or E(Planck) = M(Planck)c(2) approximately 1.22 x 10(19) GeV), at which quantum effects are expected to strongly affect the nature of space-time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in gamma-ray burst (GRB) light-curves. Here we report the detection of emission up to approximately 31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E(Planck) on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l(Planck)/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories in which the quantum nature of space-time on a very small scale linearly alters the speed of light.
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Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range â¼90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above â¼200 GeV, respectively.
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We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 GeV. We confirm that the fraction rises with energy in the 20-100 GeV range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.
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Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10(-26) cm3 s(-1) at 5 GeV to about 5×10(-23) cm3 s(-1) at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (â¼3×10(-26) cm3 s(-1) for a purely s-wave cross section), without assuming additional boost factors.
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OBJECTIVE: Upper gastrointestinal bleeding (UGIB) is a cause of Emergency Department (ED) visits. Peptic ulcer secondary to H. pylori (HP) infection and/or to the use of NSAIDs is the most frequent cause. The aim of the study is to evaluate directly in the ED the prevalence of HP infection through Urea Breath test (UBT) in patients admitted to the ED for UGIB. PATIENTS AND METHODS: We enrolled 87 patients (58M/29F) with a mean age of 63.8 + 11.7 yrs with an active UGIB who performed EGDS and UBT. RESULTS: 34.4% of patients performing EGDS and UBT resulted positive to HP. Peptic ulcer was present in 20/30 (66.7%) of HP+ compared to 20/57 (35.1%) of HP- (p<0.001), and also gastritis and/or duodenitis were mostly present in HP+ (23.3% vs. 15.8%) (p<0.05). A biopsy was performed in only 31% of patients with a positive rate of 33.3%. In 78% we obtained a correspondence between UBT and biopsy results. Compared to biopsy result, we obtained for UBT a positive predictive value (PPV) of 71% and a negative predictive value (NPV) of 80%. Taking the UBT as a gold standard, we obtained for biopsies a PPV of 69% and a NPV of 85%. CONCLUSIONS: Our study confirms that the use of UBT directly in ED in patients with UGIB allows for a rapid, reliable and non-invasive diagnosis of HP infection as a causative agent for bleeding, thus permitting a right etiological treatment.
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Testes Respiratórios , Serviço Hospitalar de Emergência , Hemorragia Gastrointestinal/diagnóstico , Infecções por Helicobacter/diagnóstico , Ureia/química , Isótopos de Carbono , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extragalactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic gamma-ray emission, the detected LAT sources, and the solar gamma-ray emission. We find the spectrum of the EGB is consistent with a power law with a differential spectral index gamma = 2.41 +/- 0.05 and intensity I(>100 MeV) = (1.03 +/- 0.17) x 10(-5) cm(-2) s(-1) sr(-1), where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.
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Dark matter (DM) particle annihilation or decay can produce monochromatic gamma rays readily distinguishable from astrophysical sources. gamma-ray line limits from 30 to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20-300 GeV are presented using a selection based on requirements for a gamma-ray line analysis, and integrated over most of the sky. We obtain gamma-ray line flux upper limits in the range 0.6-4.5x10{-9} cm{-2} s{-1}, and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.
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Acute SARS-CoV-2 respiratory disease is an infectious respiratory disease caused by the virus SARS-CoV-2 belonging to the coronaviridae family. A pandemic is still present as of May 2020. In addition to causing pneumonia, SARS-CoV-2 may induce a direct damage to the heart, causing myocarditis, with significant impairment of cardiac contractility, and/or pericarditis. Elderly patients and those with cardiovascular risk factors, such as hypertension and diabetes mellitus, are at increased risk of heart complications from COVID-19. In this review, we focused on the correlation between COVID-19 infection and the high sensitivity troponin T and I, and their significance in the development of myocarditis. Data emerging from the studies so far conducted indicate that a high value of high-sensitivity troponin represents a negative prognostic indicator when associated with heart damage on an infectious-inflammatory basis (i.e. myopericarditis). We should identify a safe and clear diagnostic algorithm, possibly combining patient clinical history, troponin levels and cardiac ultrasound findings that could help us in the prediction of myopericarditis.
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COVID-19/diagnóstico , Miocardite/diagnóstico , Troponina I/sangue , Troponina T/sangue , COVID-19/sangue , COVID-19/complicações , Humanos , Miocardite/sangue , Miocardite/complicações , Pandemias , Prognóstico , SARS-CoV-2RESUMO
OBJECTIVE: Acute alcohol intoxication is actually a common admission cause in the Emergency Department and represents an increasing public health burden, in particular among adolescents. It involves possible and significant illness and injury, which can quickly get worse and may need to be managed in the emergency room. MATERIALS AND METHODS: We conducted a narrative review of the literature regarding the effectiveness of first aid role of the Emergency Department setting. RESULTS: This review included eighteen studies about alcohol intoxication management in the Emergency Department; most of all highlights the emerging phenomenon in Europe and around the world of acute alcohol intoxication management in first aid. The treatment of acute alcohol intoxication depends on general clinical conditions of the patient, vital signs, hemodynamic stability, cognitive state, alcohol-related complications, which are closely related to the blood alcohol concentration. At the same time, symptoms could be extremely variable due to individual differences in alcohol metabolism. In case of mild-moderate intoxication (blood alcohol concentration < 1 g/L), no drugs are necessary. In case of severe intoxication (blood alcohol concentration > 1 g/L), it is necessary to support with intravenous fluids, treat hypoglycemia, hypotension, hypothermia and electrolyte imbalance, administer complex B and C vitamins and accelerate alcohol elimination from blood with metadoxine. Unlike adults, adolescents are more exposed to the toxic effect of alcohol (because of their immature hepatic alcohol dehydrogenase activity), and then, acute alcohol-related complications are more frequent and dangerous in young people than in adult population. In many cases, patients affected by acute alcohol intoxication referring to an Emergency Department have mild-moderate transitory symptoms that do not require the use of drugs; they can benefit from a clinical observation, with a clinical course often completed within 24 hours with a favorable outcome. Clinical observation with vital signs control is necessary also to evaluate the possible development of the alcohol withdrawal syndrome (that involves a specific treatment) and to evaluate also possible pathological complications of the organism, above all acute liver damage. CONCLUSIONS: Patients affected by acute alcohol intoxication are the best candidates to apply the rules of the Temporary Observation Unit in the Emergency Department, because of a clinical course often completed within 24 hours, a favorable outcome and without the need for hospitalization. In many cases, hospitalization could be not necessary, but the patient affected by Alcohol Use Disorder must be referred to an Alcohol Addiction Unit for the follow-up, to reduce the risk of alcohol relapse and complications related to alcohol abuse, and financial costs of hospitalization.
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Intoxicação Alcoólica , Primeiros Socorros , Intoxicação Alcoólica/complicações , Intoxicação Alcoólica/diagnóstico , Intoxicação Alcoólica/terapia , Concentração Alcoólica no Sangue , Serviço Hospitalar de Emergência/estatística & dados numéricos , Hospitalização/estatística & dados numéricos , HumanosRESUMO
The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.
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OBJECTIVE: Acute Uncomplicated Diverticulitis (AUD) is defined as the inflammation of a colon diverticulum, often involving colic wall and pericolic fat. Conventional treatment of AUD includes antibiotics, usually ciprofloxacin and metronidazole, fasting, and fluid therapy. The aim of this study was to test the efficacy of a mix of three probiotic strains (Bifidobacterium lactis LA 304, Lactobacillus salivarius LA 302, Lactobacillus acidophilus LA 201; Lactibiane Iki®, Biocure [PiLeJe Groupe], Italy/PiLeJe Laboratoire, France) in association with conventional antibiotics in treating AUD compared to conventional antibiotics used alone. PATIENTS AND METHODS: We enrolled 84 (25M/59F mean age 61.5 ± 11.5 years) consecutive patients who came to the Emergency Department of the Fondazione Policlinico Universitario A. Gemelli - IRCCS, Rome, Italy, with a diagnosis of AUD confirmed by CT scan. After routine blood test and dosage of C-reactive protein (C-RP), patients were randomly divided into two groups: Probiotic group (42 patients, 10M/32F mean age 32.23 ± 10.3 years) was treated with ciprofloxacin 400 mg twice a day and metronidazole 500 mg three times a day for one week and simultaneously supplemented with the probiotic mix, 1 sachet twice a day for 10 days. Control group (42 patients, 15M/27F mean age 59.01 ± 11.3 years) received the same antibiotic treatment without the probiotic mix. All patients filled a daily Visual Analog Scale (VAS) for assessment of abdominal pain, with a range value from 0 (asymptomatic) to 10, and CRP value was determined on admission and at discharge. RESULTS: As regards abdominal pain, on Day 3, Group A showed a significant decrease of 4.06 points (51.4%) in VAS score compared to a decrease of 2.79 points (34.9%) in Group B. On Day 5 the decrease was of 6.3 points (80%) in Group A and of 4.85 points (61%) in Group B. VAS score was reduced by 7.59 points (96%) in Group A and 6.1 points (76%) in Group B on Day 7 +, and by 7.8 points (99%) in Group A and 7.2 points (90%) in Group B on Day 10. About inflammation, Group A showed a decrease in C-RP value of 64%, compared to a decrease of only 35% in Group B. We also observed that the duration of hospitalization was significantly shorter for patients in Group A: 89 h (3.7 days) in Group A vs. 101 h (4.2 days) in Group B (p=0.03). CONCLUSIONS: Our results indicated showed that the supplement with the probiotic mix of Bifidobacterium lactis LA 304, Lactobacillus salivarius LA 302, and Lactobacillus acidophilus LA 201 in combination with the standard antibiotic therapy for AUD reduced abdominal pain and inflammation significantly more than antibiotic treatment used alone. These findings could be due to the anti-inflammatory activity of the probiotic mix. Larger studies are needed to validate its use in the clinical practice.
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Antibacterianos/administração & dosagem , Bifidobacterium animalis/fisiologia , Diverticulite/terapia , Lactobacillus acidophilus/fisiologia , Ligilactobacillus salivarius/fisiologia , Probióticos/administração & dosagem , Dor Abdominal/etiologia , Idoso , Antibacterianos/farmacologia , Proteína C-Reativa/metabolismo , Estudos de Casos e Controles , Ciprofloxacina/administração & dosagem , Ciprofloxacina/farmacologia , Terapia Combinada , Diverticulite/imunologia , Feminino , Humanos , Masculino , Metronidazol/administração & dosagem , Metronidazol/farmacologia , Pessoa de Meia-Idade , Projetos Piloto , Probióticos/farmacologia , Resultado do Tratamento , Escala Visual AnalógicaRESUMO
Gamma-ray burst (GRB) 130427A is one of the most energetic GRBs ever observed. The initial pulse up to 2.5 seconds is possibly the brightest well-isolated pulse observed to date. A fine time resolution spectral analysis shows power-law decays of the peak energy from the onset of the pulse, consistent with models of internal synchrotron shock pulses. However, a strongly correlated power-law behavior is observed between the luminosity and the spectral peak energy that is inconsistent with curvature effects arising in the relativistic outflow. It is difficult for any of the existing models to account for all of the observed spectral and temporal behaviors simultaneously.
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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 γ-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.
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Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement that supernova remnants (SNRs) are the sources of galactic cosmic rays, unequivocal evidence for the acceleration of protons in these objects is still lacking. When accelerated protons encounter interstellar material, they produce neutral pions, which in turn decay into gamma rays. This offers a compelling way to detect the acceleration sites of protons. The identification of pion-decay gamma rays has been difficult because high-energy electrons also produce gamma rays via bremsstrahlung and inverse Compton scattering. We detected the characteristic pion-decay feature in the gamma-ray spectra of two SNRs, IC 443 and W44, with the Fermi Large Area Telescope. This detection provides direct evidence that cosmic-ray protons are accelerated in SNRs.
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Millisecond pulsars, old neutron stars spun up by accreting matter from a companion star, can reach high rotation rates of hundreds of revolutions per second. Until now, all such "recycled" rotation-powered pulsars have been detected by their spin-modulated radio emission. In a computing-intensive blind search of gamma-ray data from the Fermi Large Area Telescope (with partial constraints from optical data), we detected a 2.5-millisecond pulsar, PSR J1311-3430. This unambiguously explains a formerly unidentified gamma-ray source that had been a decade-long enigma, confirming previous conjectures. The pulsar is in a circular orbit with an orbital period of only 93 minutes, the shortest of any spin-powered pulsar binary ever found.
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The light emitted by stars and accreting compact objects through the history of the universe is encoded in the intensity of the extragalactic background light (EBL). Knowledge of the EBL is important to understand the nature of star formation and galaxy evolution, but direct measurements of the EBL are limited by galactic and other foreground emissions. Here, we report an absorption feature seen in the combined spectra of a sample of gamma-ray blazars out to a redshift of z â¼ 1.6. This feature is caused by attenuation of gamma rays by the EBL at optical to ultraviolet frequencies and allowed us to measure the EBL flux density in this frequency band.
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Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.
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A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 × 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.
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The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little of their escape from the shock and their evolution through the turbulent medium surrounding massive stars. Gamma rays can probe their spreading through the ambient gas and radiation fields. The Fermi Large Area Telescope (LAT) has observed the star-forming region of Cygnus X. The 1- to 100-gigaelectronvolt images reveal a 50-parsec-wide cocoon of freshly accelerated cosmic rays that flood the cavities carved by the stellar winds and ionization fronts from young stellar clusters. It provides an example to study the youth of cosmic rays in a superbubble environment before they merge into the older Galactic population.
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Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.