Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 165
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Phys Rev Lett ; 132(2): 021001, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38277596

RESUMO

We show, for the first time, radio measurements of the depth of shower maximum (X_{max}) of air showers induced by cosmic rays that are compared to measurements of the established fluorescence method at the same location. Using measurements at the Pierre Auger Observatory we show full compatibility between our radio and the previously published fluorescence dataset, and between a subset of air showers observed simultaneously with both radio and fluorescence techniques, a measurement setup unique to the Pierre Auger Observatory. Furthermore, we show radio X_{max} resolution as a function of energy and demonstrate the ability to make competitive high-resolution X_{max} measurements with even a sparse radio array. With this, we show that the radio technique is capable of cosmic-ray mass composition studies, both at Auger and at other experiments.

2.
Phys Rev Lett ; 130(6): 061001, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36827568

RESUMO

Instantons, which are nonperturbative solutions to Yang-Mills equations, provide a signal for the occurrence of quantum tunneling between distinct classes of vacua. They can give rise to decays of particles otherwise forbidden. Using data collected at the Pierre Auger Observatory, we search for signatures of such instanton-induced processes that would be suggestive of super-heavy particles decaying in the Galactic halo. These particles could have been produced during the post-inflationary epoch and match the relic abundance of dark matter inferred today. The nonobservation of the signatures searched for allows us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: α_{X}≲0.09, for 10^{9}≲M_{X}/GeV<10^{19}. Conversely, we obtain that, for instance, a reduced coupling constant α_{X}=0.09 excludes masses M_{X}≳3×10^{13} GeV. In the context of dark matter production from gravitational interactions alone, we illustrate how these bounds are complementary to those obtained on the Hubble rate at the end of inflation from the nonobservation of tensor modes in the cosmological microwave background.

3.
Phys Rev Lett ; 126(15): 152002, 2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33929235

RESUMO

We present the first measurement of the fluctuations in the number of muons in extensive air showers produced by ultrahigh energy cosmic rays. We find that the measured fluctuations are in good agreement with predictions from air shower simulations. This observation provides new insights into the origin of the previously reported deficit of muons in air shower simulations and constrains models of hadronic interactions at ultrahigh energies. Our measurement is compatible with the muon deficit originating from small deviations in the predictions from hadronic interaction models of particle production that accumulate as the showers develop.

4.
Phys Rev Lett ; 126(9): 091101, 2021 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-33750144

RESUMO

We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties of dark matter (DM). This analysis fully incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and marginalizes over uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk. Our results are consistent with the cold, collisionless DM paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. At 95% confidence, we report limits on (i) the mass of thermal relic warm DM, m_{WDM}>6.5 keV (free-streaming length, λ_{fs}≲10h^{-1} kpc), (ii) the velocity-independent DM-proton scattering cross section, σ_{0}<8.8×10^{-29} cm^{2} for a 100 MeV DM particle mass [DM-proton coupling, c_{p}≲(0.3 GeV)^{-2}], and (iii) the mass of fuzzy DM, m_{ϕ}>2.9×10^{-21} eV (de Broglie wavelength, λ_{dB}≲0.5 kpc). These constraints are complementary to other observational and laboratory constraints on DM properties.

5.
Phys Rev Lett ; 125(12): 121106, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-33016715

RESUMO

We report a measurement of the energy spectrum of cosmic rays above 2.5×10^{18} eV based on 215 030 events. New results are presented: at about 1.3×10^{19} eV, the spectral index changes from 2.51±0.03(stat)±0.05(syst) to 3.05±0.05(stat)±0.10(syst), evolving to 5.1±0.3(stat)±0.1(syst) beyond 5×10^{19} eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5×10^{18} eV is [5.66±0.03(stat)±1.40(syst)]×10^{53} erg Mpc^{-3}.

6.
Phys Rev Lett ; 124(10): 101102, 2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32216401

RESUMO

In recent years, many γ-ray sources have been identified, yet the unresolved component hosts valuable information on the faintest emission. In order to extract it, a cross-correlation with gravitational tracers of matter in the Universe has been shown to be a promising tool. We report here the first identification of a cross-correlation signal between γ rays and the distribution of mass in the Universe probed by weak gravitational lensing. We use data from the Dark Energy Survey Y1 weak lensing data and the Fermi Large Area Telescope 9-yr γ-ray data, obtaining a signal-to-noise ratio of 5.3. The signal is mostly localized at small angular scales and high γ-ray energies, with a hint of correlation at extended separation. Blazar emission is likely the origin of the small-scale effect. We investigate implications of the large-scale component in terms of astrophysical sources and particle dark matter emission.

7.
Phys Rev Lett ; 123(18): 181301, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31763885

RESUMO

We report the first detection of gravitational lensing due to galaxy clusters using only the polarization of the cosmic microwave background (CMB). The lensing signal is obtained using a new estimator that extracts the lensing dipole signature from stacked images formed by rotating the cluster-centered Stokes QU map cutouts along the direction of the locally measured background CMB polarization gradient. Using data from the SPTpol 500 deg^{2} survey at the locations of roughly 18 000 clusters with richness λ≥10 from the Dark Energy Survey (DES) Year-3 full galaxy cluster catalog, we detect lensing at 4.8σ. The mean stacked mass of the selected sample is found to be (1.43±0.40)×10^{14}M_{⊙} which is in good agreement with optical weak lensing based estimates using DES data and CMB-lensing based estimates using SPTpol temperature data. This measurement is a key first step for cluster cosmology with future low-noise CMB surveys, like CMB-S4, for which CMB polarization will be the primary channel for cluster lensing measurements.

8.
Phys Rev Lett ; 116(24): 241101, 2016 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-27367377

RESUMO

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8±0.7(stat)±6.7(syst) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.

9.
Phys Rev Lett ; 117(19): 192001, 2016 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-27858429

RESUMO

Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_{CM}=110-170 TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33±0.16 (1.61±0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.

10.
J Clin Microbiol ; 52(1): 335-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24226916

RESUMO

We pretreated with SDS 71 urine samples with bacterial counts of >10(5) CFU/ml and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) identification scores of <2, in order to minimize failure rates. Identification improved in 46.5% of samples, remained unchanged in 49.3%, and worsened in 4.2%. The improvement was more evident for Gram-negative (54.3%) than for Gram-positive (32%) bacteria.


Assuntos
Bactérias/isolamento & purificação , Infecções Bacterianas/diagnóstico , Técnicas Microbiológicas/métodos , Manejo de Espécimes/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Infecções Urinárias/diagnóstico , Urina/microbiologia , Bactérias/classificação , Detergentes/farmacologia , Humanos , Dodecilsulfato de Sódio/farmacologia
11.
Phys Rev Lett ; 109(6): 062002, 2012 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-23006259

RESUMO

We report a measurement of the proton-air cross section for particle production at the center-of-mass energy per nucleon of 57 TeV. This is derived from the distribution of the depths of shower maxima observed with the Pierre Auger Observatory: systematic uncertainties are studied in detail. Analyzing the tail of the distribution of the shower maxima, a proton-air cross section of [505±22(stat)(-36)(+28)(syst)] mb is found.

12.
Rev Esp Quimioter ; 35(3): 273-278, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35441836

RESUMO

OBJECTIVE: Hepatitis C virus (HCV) infection is a major public health problem that causes multiple comorbidities. People in prisons who inject intravenous drugs are at increased risk of HCV infection, and HCV infection is 15-fold more prevalent among prisoners compared with the community. The objective of this study was to analyse the clinical and epidemiological characteristics of residents of a Spanish prison with HCV infection who received antiviral treatment. METHODS: An observational, descriptive and retrospective study was performed. All patients with HCV infection diagnosed or followed up in an Infectious Diseases attached to a penitentiary were included in this study. RESULTS: Of 81 patients analysed, sixty-nine (83.1%) patients were male. The mean age was 50.1 (SD8.8) years, and 70% of the inmates had a history of injection drug use. Coinfection with HIV was detected in 30%. In up to 25% of the sample, there were data on chronic liver disease in the degree of liver cirrhosis. The diagnosis of HCV infection had been made more than 15 years earlier in 28% of those studied. Decompensations from liver disease, hepatocellular carcinoma, or hospital admissions were exceptional. Most of the inmates with HCV accepted treatment, and approximately 94% of the patients who completed treatment achieved a sustained virological response without interactions or complications of interest. CONCLUSIONS: The availability of direct-acting antivirals and their exceptional side effects constitute an opportunity to reduce the burden of HCV infection in Spain, particularly in these high-risk populations.


Assuntos
Hepatite C Crônica , Hepatite C , Antivirais/uso terapêutico , Feminino , Hepacivirus , Hepatite C/complicações , Hepatite C/tratamento farmacológico , Hepatite C/epidemiologia , Hepatite C Crônica/tratamento farmacológico , Hepatite C Crônica/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Prisões , Estudos Retrospectivos
13.
Phys Rev Lett ; 104(9): 091101, 2010 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-20366976

RESUMO

We describe the measurement of the depth of maximum, X{max}, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10;{18} eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106{-21}{+35}) g/cm{2}/decade below 10{18.24+/-0.05} eV, and (24+/-3) g/cm{2}/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm{2}. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.

14.
Rev Esp Quimioter ; 21 Spec No 1: 2-6, 2008.
Artigo em Espanhol | MEDLINE | ID: mdl-18752073

RESUMO

INTRODUCTION: Because of the special characteristics of the critical patients, infections are one of the primary complications they suffer so that multiresistant microorganisms take on a special importance in this type of patient. SOURCES: Search in Medline using the words ICU (Intensive Care Unit), multidrug resistant, critical patient. DEVELOPMENT: Glycopeptide resistant enterococci show a reduced prevalence in our setting and the VISA and hVISA are isolated sporadically. MRSA is, on the other hand, a major problem. In 2003-2005, it was already accounting for 28 %-38 % of the S. aureus isolated in the ICU, with a high percentage of fluoroquinolone (>90 %) and macrolide (>65 %) co-resistance. The extended-spectrum beta-lactamase producing enterobacteria (BLEE) also are a growing problem, worsened by their frequent co-resistance with fluoroquinolones, about 30 % according to some studies. Carbapenem resistance in A. baumannii has doubled in recent years, with values greater than 50 %, almost always associated to enzymes of the OXA group. P. aeruginosa also maintains high resistance values (25 %-30 % of resistance to imipenem, ceftazidime or ciprofloxacin), but more stable. However, high rates of multi-resistance are also observed, now about 50 % of the isolations of imipenem resistant P. aeruginosa are also to fluoroquinolones. As a whole, recent studies show that the multiresistance has multiplied in recently years by 5 in P. aeruginosa and by 7 in A. baumannii. CONCLUSIONS: Multiresistant bacteria infections are one of the greatest problems to combat in critical patients and control of their spreading and the development of active antimicrobials against them is one of the principal challenges at present.


Assuntos
Infecções Bacterianas/tratamento farmacológico , Farmacorresistência Bacteriana Múltipla , Estado Terminal , Humanos
15.
J Chemother ; 19(3): 263-70, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17594920

RESUMO

The susceptibility patterns of 2724 uropathogens isolated in 9 Spanish regions during 2002, and 3013 obtained in 2004 were determined. The antibiotics tested were fosfomycin trometamol, amoxicillin, co-amoxiclav, cefixime, cefuroxime-axetil, pipemidic, ceprofloxacin, trimethoprim plus sulphamethoxazole and nitrofurantoin. Escherichia coli was the main pathogen in both studies (73% vs. 68.3%) followed by Proteus mirabilis 7.2% vs. 6.4%) and Klebsiella pneumoniae (5.4% vs. 5.2%). Enteroccocus spp. (4.7% vs. 6.8%), Streptoccocus agalactiae (1.7% vs. 3.1%) and Staphyloccocus saprophyticus (0.7% vs. 1.3%)were the most frequent Gram-positive pathogens. 31.3% of E. coli in 2002 and 32% in 2004 were susceptible to all antibiotics tested. Around 40% of E. coli were resistant to a single agent. 21.6-24.1% were resistant to two antibiotics. 35.4% of first period isolates, and 37.6% of second period ones were resistant to two or more classes of antibiotics. Fosfomycin (2.1- 2.8%) and nitrofurantoin (3.5-5.7%) had the lowest resistance rates for E. coli. Amoxicillin (58.2-58.7%), co-trimoxazole (30.8-33.8%) and ciprofloxacin (22.6-22.7%) showed the highest resistance rates, and their suitability as empiric treatments for UTI should probably be re-evaluated.


Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Infecções Comunitárias Adquiridas/microbiologia , Farmacorresistência Bacteriana Múltipla , Infecções Urinárias/microbiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Infecções Comunitárias Adquiridas/epidemiologia , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Espanha/epidemiologia , Infecções Urinárias/epidemiologia
16.
Rev Esp Quimioter ; 30(6): 391-396, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29082727

RESUMO

Daptomycin is a cyclic lipopeptide active against multidrug-resistant Gram-positives, including methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus with reduced susceptibility to vancomycin. It is 4-8 fold as active as vancomycin against methicillin-susceptible S. aureus (MSSA) and MRSA, and retains most of this activity against S. aureus with reduced susceptibility to vancomycin. The mechanism of action of daptomycin is not fully understood. Daptomycin binds to the bacterial cytoplasmic membrane, leading to depolarization due to the loss of potassium ions from the cytoplasm. Daptomycin non-susceptibility is unusual in the clinical setting. Different mechanisms have been proposed to explain daptomycin-resistance, most of them associated to changes in composition, charge and fluidity of the cell wall. The mprF mutations, which lead to an increase in the lysyl-phosphatidyl glycerol production, and rpoB and rpoC mutations (rpo genes encode for bacterial RNA polymerase subunits) have been proposed as associated to daptomycin-resistance, but a number of mutations in other genes ( walK, cls, ggrA…) have been proposed.


Assuntos
Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Daptomicina/farmacologia , Daptomicina/uso terapêutico , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Humanos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética
17.
J Epidemiol Community Health ; 60(4): 328-36, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16537350

RESUMO

OBJECTIVE: To evaluate the short term effect of air pollution on cardiovascular admissions in 14 Spanish cities METHODS: The period under study was from 1995 to 1999. Daily emergency admissions for all cardiovascular diseases (CVD) and heart diseases (HD) were obtained from hospital records, and the corresponding daily levels of particulates, SO2, NO2, CO, and ozone were recorded. The magnitude of association was estimated using Poisson generalised additive models controlling for confounding and overdispersion. For each cause, lagged effects, up to three days, of each pollutant were examined and combined estimates were obtained. For ozone the analyses were restricted to the warm period. One and two pollutant models were performed. RESULTS: Associations were more consistent in lag 0 (concurrent day) and 1 (lag 0-1), except in the case of ozone where there was a more delayed relation (lag 2-3). For combined estimates an increase of 10 microg/m3 in the PM10 levels in lag 0-1 was associated with an increase of 0.9% (95% CI: 0.4 to 1.5%) in the number of hospital admissions for CVD, and 1.6% (0.8 to 2.3%) for HD. For ozone the corresponding estimates for lag 2-3 were 0.7% (0.3 to 1.0) for CVD, and 0.7% (0.1 to 1.2) for HD. An increase of 1 mg/m3 in CO levels was associated with an increase of 2.1% (0.7 to 3.5%) in CVD admissions, and 4.2% (1.3 to 7.1%) in HD admissions. SO2 and NO2 estimates were more sensitive in two pollutant models CONCLUSIONS: A short term association between increases in daily levels of air pollutants and the number of daily admissions for cardiovascular diseases, with specificity for heart diseases, has been described in Spanish cities.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Doenças Cardiovasculares/epidemiologia , Hospitalização/estatística & dados numéricos , Idoso , Monóxido de Carbono/efeitos adversos , Feminino , Humanos , Masculino , Dióxido de Nitrogênio/efeitos adversos , Ozônio/efeitos adversos , Fumaça/efeitos adversos , Espanha/epidemiologia , Dióxido de Enxofre/efeitos adversos
18.
Rev Esp Quimioter ; 19(2): 152-60, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16964333

RESUMO

One hundred and forty-seven Salmonella serotype Typhimurium strains isolated in three provinces in the midwest of Spain were studied. Of these, 93.6% were drug resistant. There were two predominant resistance phenotypes: 43 isolates (29.3%) were resistant to amoxicillin, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole and 27 isolates (18.4%) to amoxicillin, amoxicillin/clavulanic acid, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole. Randomly amplified polymorphic DNA (RAPD) analysis and pulsed field gel electrophoresis (PFGE) were performed for molecular typing. Thirty-six DNA band profiles were differentiated by RAPD, and 38 by PFGE. We found a high level of clonality; 27% of strains were identical by both methods. There were additional smaller clonal lines within every area. The highest discriminatory power was obtained with PFGE, but the greatest degree of genetic diversity was observed among Salmonella Typhimurium using both RAPD and PFGE.


Assuntos
Farmacorresistência Bacteriana , Infecções por Salmonella/epidemiologia , Salmonella typhimurium/genética , Humanos , Infecções por Salmonella/microbiologia , Salmonella typhimurium/efeitos dos fármacos , Espanha/epidemiologia
19.
New Microbes New Infect ; 9: 47-9, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26862434

RESUMO

Small colony variants (SCV) are slow-growing subpopulations of bacteria usually associated with auxotrophism, causing persistent or recurrent infections. Enterococcus faecalis SCV have been seldom described, and only one case of Enterococcus faecium SCV has been reported, associated with sepsis in a leukaemia patient. Here we report the first case described of bacteraemia and endocarditis by SCV E. faecium in an immunocompetent patient.

20.
J Virol Methods ; 230: 18-23, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26784284

RESUMO

Hepatitis E virus (HEV) genotype 3 produces zoonotic infection associated with the consumption of infected animals. HEV infections can become chronic in immunocompromised (IC) patients. The viral genome has three well defined open reading frames (ORF1, ORF2 and ORF3) within which various domains and functions have been described. This paper (i) describes a new method of complete sequencing of the HEV coding region through overlapping PCR systems, (ii) establishes a consensus sequence and polymorphic positions (PP) for each domain, and (iii) analyzes the complete coding sequence of an IC patient. With regard to the consensus, a high percentage of PP was observed in protease (PP=19%) and the X domain (PP=22%) within ORF1, the N-terminal region of the S domain (PP=22%) in ORF2, and the P1 (PP=35%) and P2 (PP=25%) domains in ORF3. In contrast, the ORF1 Y, ORF2 S, ORF2 M and ORF3 D1 domains were conserved in the reference sequences (0.40, 1, 0.70 and 0% of PP, respectively). The sequence from the IC patient had more mutations in the RpRp (D1235G, Q1242R, S1454T, V1480I, I1502 V, K1511R, G1373 V, E1442D, V1693 M), the terminal ORF2 S- domain (F10L, S26T, G36S, S70P, A105 V, I113 V), the X domain (T938 M, T856 V, S898A) and the helicase (S1014N, S975T, Q1133 K).


Assuntos
Genoma Viral , Genômica/métodos , Vírus da Hepatite E/genética , Hepatite E/virologia , Humanos , Mutação , Fases de Leitura Aberta
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA