Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 152
Filtrar
1.
Phys Rev Lett ; 132(4): 041001, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38335333

RESUMO

With excellent energy resolution and ultralow-level radiogenic backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter (DM) models. In this work, we report new experimental limits on keV-scale sterile neutrino DM via the transition magnetic moment from conversion to active neutrinos ν_{s}→ν_{a}. We report new limits on fermionic dark matter absorption (χ+A→ν+A) and sub-GeV DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), and new exclusion limits for bosonic dark matter (axionlike particles and dark photons). These searches utilize the (1-100)-keV low-energy region of a 37.5-kg y exposure collected by the Demonstrator between May 2016 and November 2019 using a set of ^{76}Ge-enriched detectors whose surface exposure time was carefully controlled, resulting in extremely low levels of cosmogenic activation.

2.
Phys Rev Lett ; 131(15): 152501, 2023 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-37897780

RESUMO

^{180m}Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known ß and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower-energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter, and K-spin violation. For this study, we repurposed the Majorana Demonstrator, an experimental search for the neutrinoless double-beta decay of ^{76}Ge using an array of high-purity germanium detectors, to search for the decay of ^{180m}Ta. More than 17 kg, the largest amount of tantalum metal ever used for such a search, was installed within the ultralow-background detector array. In this Letter, we present results from the first year of Ta data taking and provide an updated limit for the ^{180m}Ta half-life on the different decay channels. With new limits up to 1.5×10^{19} yr, we improved existing limits by 1-2 orders of magnitude which are the most sensitive searches for a single ß and electron capture decay ever achieved. Over all channels, the decay can be excluded for T_{1/2}<0.29×10^{18} yr.

3.
Appl Radiat Isot ; 200: 110913, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37442027

RESUMO

This paper describes a procedure for the validation of alpha-particle sources (exempt unsealed sources) to be used in experimental setups with liquefied gases at cryogenic temperatures (down to -196 °C) and high vacuum. These setups are of interest for the development and characterization of neutrino and dark matter detectors based on liquid argon, among others. Due to the high purity requirements, the sources have to withstand high vacuum and cryogenic temperatures for extended periods. The validation procedure has been applied to 241Am sources produced by electrodeposition.

5.
Phys Rev Lett ; 130(6): 062501, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36827565

RESUMO

The Majorana Demonstrator searched for neutrinoless double-ß decay (0νßß) of ^{76}Ge using modular arrays of high-purity Ge detectors operated in vacuum cryostats in a low-background shield. The arrays operated with up to 40.4 kg of detectors (27.2 kg enriched to ∼88% in ^{76}Ge). From these measurements, the Demonstrator has accumulated 64.5 kg yr of enriched active exposure. With a world-leading energy resolution of 2.52 keV FWHM at the 2039 keV Q_{ßß} (0.12%), we set a half-life limit of 0νßß in ^{76}Ge at T_{1/2}>8.3×10^{25} yr (90% C.L.). This provides a range of upper limits on m_{ßß} of (113-269) meV (90% C.L.), depending on the choice of nuclear matrix elements.

6.
Crit Rev Food Sci Nutr ; : 1-16, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36382631

RESUMO

SARS-CoV-2 mainly affects the respiratory system, but the gastrointestinal tract is also a target. Prolonged gut disorders, in COVID-19 patients, were correlated with decreased richness and diversity of the gut microbiota, immune deregulation and delayed viral clearance. Although there are no definitive conclusions, ample evidence would suggest that the gut microbiome composition and function play a role in COVID-19 progression. Microbiome modulation strategies for population stratification and management of COVID-19 infection are under investigation, representing an area of interest in the ongoing pandemic. In this review, we present the existing data related to the interaction between gut microbes and the host's immune response to SARS-CoV-2 and discuss the implications for current disease management and readiness to face future pandemics.

7.
Phys Rev Lett ; 129(8): 080401, 2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36053678

RESUMO

The Majorana Demonstrator neutrinoless double-beta decay experiment comprises a 44 kg (30 kg enriched in ^{76}Ge) array of p-type, point-contact germanium detectors. With its unprecedented energy resolution and ultralow backgrounds, Majorana also searches for rare event signatures from beyond standard model physics in the low energy region below 100 keV. In this Letter, we test the continuous spontaneous localization (CSL) model, one of the mathematically well-motivated wave function collapse models aimed at solving the long-standing unresolved quantum mechanical measurement problem. While the CSL predicts the existence of a detectable radiation signature in the x-ray domain, we find no evidence of such radiation in the 19-100 keV range in a 37.5 kg-y enriched germanium exposure collected between December 31, 2015, and November 27, 2019, with the Demonstrator. We explored both the non-mass-proportional (n-m-p) and the mass-proportional (m-p) versions of the CSL with two different assumptions: that only the quasifree electrons can emit the x-ray radiation and that the nucleus can coherently emit an amplified radiation. In all cases, we set the most stringent upper limit to date for the white CSL model on the collapse rate, λ, providing a factor of 40-100 improvement in sensitivity over comparable searches. Our limit is the most stringent for large parts of the allowed parameter space. If the result is interpreted in terms of the Diòsi-Penrose gravitational wave function collapse model, the lower bound with a 95% confidence level is almost an order of magnitude improvement over the previous best limit.

8.
Phys Rev Lett ; 129(8): 081803, 2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36053699

RESUMO

Axions were originally proposed to explain the strong-CP problem in QCD. Through axion-photon coupling, the Sun could be a major source of axions, which could be measured in solid state detection experiments with enhancements due to coherent Primakoff-Bragg scattering. The Majorana Demonstrator experiment has searched for solar axions with a set of ^{76}Ge-enriched high purity germanium detectors using a 33 kg-yr exposure collected between January, 2017 and November, 2019. A temporal-energy analysis gives a new limit on the axion-photon coupling as g_{aγ}<1.45×10^{-9} GeV^{-1} (95% confidence level) for axions with mass up to 100 eV/c^{2}. This improves laboratory-based limits between about 1 eV/c^{2} and 100 eV/c^{2}.

10.
Ann Hematol ; 101(7): 1465-1471, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35467101

RESUMO

Most ß-thalassemias are caused by mutations involving one or a limited number of nucleotides within the gene or its adjacent regions. They can be substitutions or deletions; in these cases, the loss ranges from a single nucleotide to even the entire HBB gene, so we wonder if the phenotype is due to the size of the deletion or the location of the mutation. To clarify this, we present two new deletions in the ß-globin gene that cause ß0-thalassemia. The hematological parameters were determined with an automated cell counter; the Hb A2 and Hb F levels were measured by performance liquid chromatography. Hemoglobins were analyzed by capillary zone electrophoresis (Sebia Capillarys Flex system) and ion-exchange HPLC (BioRad Variant II ß-thalassemia Short Program). Molecular characterization was performed by automatic Sanger sequencing. The screening of common α-thalassemia point mutations and deletions in the world (21 in total) were carried out using multiplex PCR followed by reverse-hybridization with a commercial Alpha-Globin StripAssay kit. We have characterized two new mutations-(1) 1-bp deletion [CD61/62(-G)] [HBB:c.186_187delG], (2) 105-bp deletion [IVS-2-nt767-CD111] [HBB:c.316-84_333del]-and we have described, for first time in Spain, the 25-bp deletion [ß nts 252 - 276 deleted] [HBB:c.93-22_95del] mutation. These mutations were classified as pathogenic by UniProt Variants confirmed according to the American College of Medical Genetics and Genomics guidelines. These mutations present a phenotype compatible with ß0-thalassemia, supported by hematological parameters that correlate the degree of reduction in the synthesis of the ß-globin chain. Identification of this type of mutation is important for genetic counselling of partners where both are carriers, so that they are aware of the genetic risk of having affected children, allowing them to take an informed decision about their reproductive choices.


Assuntos
Talassemia alfa , Talassemia beta , Genótipo , Hemoglobina A2/genética , Hemoglobinas/genética , Humanos , Mutação , alfa-Globinas/genética , Talassemia alfa/genética , Globinas beta/genética , Talassemia beta/diagnóstico , Talassemia beta/genética
11.
Eur Phys J C Part Fields ; 82(3): 226, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35310515

RESUMO

P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We have characterized a PPC detector's response to α particles incident on the sensitive passivated and p + surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the Majorana Demonstrator experiment, a search for neutrinoless double-beta decay ( 0 ν ß ß ) in 76 Ge. α decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of α identification, reliably identifying α background events on the passivated surface of the detector. We demonstrate effective rejection of all surface α events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the 0 ν ß ß region of interest window by an order of magnitude in the Majorana Demonstrator  and will be used in the upcoming LEGEND-200 experiment.

13.
Med Intensiva ; 46(2): 81-89, 2022 Feb.
Artigo em Espanhol | MEDLINE | ID: mdl-34545260

RESUMO

The COVID-19 pandemic has led to the admission of a high number of patients to the ICU, generally due to severe respiratory failure. Since the appearance of the first cases of SARS-CoV-2 infection, at the end of 2019, in China, a huge number of treatment recommendations for this entity have been published, not always supported by sufficient scientific evidence or with methodological rigor necessary. Thanks to the efforts of different groups of researchers, we currently have the results of clinical trials, and other types of studies, of higher quality. We consider it necessary to create a document that includes recommendations that collect this evidence regarding the diagnosis and treatment of COVID-19, but also aspects that other guidelines have not considered and that we consider essential in the management of critical patients with COVID-19. For this, a drafting committee has been created, made up of members of the SEMICYUC Working Groups more directly related to different specific aspects of the management of these patients.

14.
Med Intensiva (Engl Ed) ; 46(2): 81-89, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34903475

RESUMO

The COVID-19 pandemic has led to the admission of a high number of patients to the ICU, generally due to severe respiratory failure. Since the appearance of the first cases of SARS-CoV-2 infection, at the end of 2019, in China, a huge number of treatment recommendations for this entity have been published, not always supported by sufficient scientific evidence or with methodological rigor necessary. Thanks to the efforts of different groups of researchers, we currently have the results of clinical trials, and other types of studies, of higher quality. We consider it necessary to create a document that includes recommendations that collect this evidence regarding the diagnosis and treatment of COVID-19, but also aspects that other guidelines have not considered and that we consider essential in the management of critical patients with COVID-19. For this, a drafting committee has been created, made up of members of the SEMICYUC Working Groups more directly related to different specific aspects of the management of these patients.


Assuntos
COVID-19 , Estado Terminal/terapia , Humanos , Unidades de Terapia Intensiva , Pandemias , SARS-CoV-2
15.
Front Artif Intell ; 4: 649917, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34505055

RESUMO

In liquid argon time projection chambers exposed to neutrino beams and running on or near surface levels, cosmic muons, and other cosmic particles are incident on the detectors while a single neutrino-induced event is being recorded. In practice, this means that data from surface liquid argon time projection chambers will be dominated by cosmic particles, both as a source of event triggers and as the majority of the particle count in true neutrino-triggered events. In this work, we demonstrate a novel application of deep learning techniques to remove these background particles by applying deep learning on full detector images from the SBND detector, the near detector in the Fermilab Short-Baseline Neutrino Program. We use this technique to identify, on a pixel-by-pixel level, whether recorded activity originated from cosmic particles or neutrino interactions.

17.
J Hosp Infect ; 108: 7-14, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33181279

RESUMO

BACKGROUND: Serratia marcescens frequently causes outbreaks in healthcare settings. There are few studies using high-throughput sequencing (HTS) that analyse S. marcescens outbreaks. We present the analysis of two outbreaks in neonatal intensive care units (NICUs) in hospitals from the Comunitat Valenciana (CV, Spain) and the impact of using different reference genomes. METHODS: DNA from cultured isolates was extracted and sequenced by HTS using Illumina NextSeq. Reads were mapped against two reference genomes, strains UMH9 and Db11, and the unmapped fraction of the genomes was assembled to fully genetically characterize the isolates. FINDINGS: Isolates from the first outbreak were identical to the UMH9 reference, an unrelated isolate obtained three years earlier in the USA. This did not occur when the Db11 strain, a standard reference for S. marcescens, was used as the reference for mapping. To check whether UMH9 was a widely distributed clone spreading in the CV, the second outbreak isolates were mapped against this reference. They were not closely related to this strain, and this outbreak could be defined as such regardless of the reference used for mapping the reads. CONCLUSIONS: The choice of the reference for genomic analysis of outbreaks is a critical decision. In the case of the first outbreak, this choice changed the interpretation of the results drastically, allowing or preventing the definition of the outbreak according to the reference used. Although HTS is a powerful tool for epidemiological analysis, it is still essential to collect microbiological and epidemiological data for the correct interpretation of the results.


Assuntos
Infecção Hospitalar , Surtos de Doenças , Infecções por Serratia , Serratia marcescens/classificação , Células Clonais , Infecção Hospitalar/epidemiologia , Humanos , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Testes de Sensibilidade Microbiana , Infecções por Serratia/epidemiologia , Espanha
18.
Clin Immunol ; 210: 108307, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31760095

RESUMO

An increasing healthcare challenge in the management of haematological malignancy (HM) is secondary immunodeficiency. From January 2019, the EMA included the evaluation of specific antibody (Ab) responses to better select patients for immunoglobulin replacement therapy (IgRT). We evaluated Ab responses to pneumococcal and Salmonella typhi pure polysaccharide immunization in a cohort of 42 HM patients and 24 healthy-controls. Pre-post specific Ab concentrations were measured by ELISA at 4 weeks. Globally, significantly lower Typhim Vi (TV) seroprevalence (9%) compared to 23-valent pneumococcal polysaccharide vaccine (PPV) (76%) (p <0.001) was observed. TV non responders (88%) were higher than PPV non responders (62%) (p <0.0001) and correlated better to infectious history. By ROC analysis, pre-post 5-fold TV increase was the best cut-off to discriminate HM with recurrent infections and controls (sensitivity 91%, specificity 100%). Despite the small sample cohort, our results suggest that specific anti-S typhi Ab response is a useful complementary assay in the diagnosis and management decision of SID to HM.


Assuntos
Neoplasias Hematológicas/diagnóstico , Síndromes de Imunodeficiência/diagnóstico , Polissacarídeos Bacterianos/imunologia , Salmonella typhi/fisiologia , Febre Tifoide/imunologia , Vacinas Tíficas-Paratíficas/imunologia , Adulto , Idoso , Anticorpos Antibacterianos/sangue , Formação de Anticorpos , Estudos de Coortes , Feminino , Neoplasias Hematológicas/epidemiologia , Neoplasias Hematológicas/imunologia , Humanos , Síndromes de Imunodeficiência/epidemiologia , Síndromes de Imunodeficiência/imunologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Estudos Soroepidemiológicos , Espanha/epidemiologia
19.
Rev Neurol ; 69(9): 363-369, 2019 Nov 01.
Artigo em Espanhol | MEDLINE | ID: mdl-31657448

RESUMO

INTRODUCTION: An alteration in the recognition of basic emotions is usually observed in Alzheimer's type dementia. Although there is some consensus that basic emotions are six, more recent studies conclude that there may be a combination between fear/ surprise and disgust/anger. This pattern has not yet been investigated in the Alzheimer's type dementia. AIMS: To evaluate if the main confusers are significant as to determine the amount of basic emotions, and to study which are the main confusers, between emotions, that are manifested in patients with Alzheimer's type dementia. PATIENTS AND METHODS: Twenty-eight patients were evaluated with the Battery of Facial Recognition of Basic Emotions. RESULTS: The highest percentages of choice for each emotion, proceeding those of correct answers, correspond to the main confusers (fear x surprise, surprise x fear, and disgust x anger). Significant differences were found between fear correct/surprise x fear, surprise correct/fear x surprise, anger correct/disgust x anger, and disgust correct/anger x disgust. CONCLUSIONS: These results support the classical theory raised on the existence of six basic emotions. As regard as emotional confusers, our results coincide partially with studies which found that the main errors are between anger/disgust and surprise/fear. As an exception, we found in our sample that when the correct answer is anger, the most common response by patients is fear.


TITLE: Reconocimiento de emociones básicas y sus principales confusores en la demencia tipo Alzheimer.Introducción. En la demencia tipo Alzheimer se suele observar alteración en el reconocimiento de las emociones básicas. Aunque existe cierto consenso en que las emociones básicas son seis, trabajos más recientes concluyen que puede haber una combinación entre miedo/sorpresa y asco/enojo. Este patrón no está investigado en la demencia tipo Alzheimer. Objetivos. Evaluar si los principales confusores son significativos para determinar la cantidad de emociones básicas y estudiar cuáles son los principales confusores entre emociones que se manifiestan en los pacientes con demencia tipo Alzheimer. Pacientes y métodos. Se evaluó a 28 pacientes con la batería de reconocimiento facial de emociones básicas. Resultados. Los porcentajes más elevados de elección para cada emoción, que proceden de las respuestas correctas, corresponden a los principales factores de confusión (miedo × sorpresa, sorpresa × miedo y asco × enojo). Se encontraron diferencias significativas entre miedo correcto/sorpresa × miedo, sorpresa correcta/miedo × sorpresa, enojo correcto/asco × enojo y asco correcto/enojo × asco. Conclusiones. Estos resultados estarían apoyando la teoría clásica planteada sobre la existencia de seis emociones básicas. Respecto a los confusores emocionales, nuestros resultados coinciden parcialmente con estudios que encontraron que los principales errores se presentan entre enojo/asco y sorpresa/miedo. Como excepción, en nuestra muestra encontramos que cuando la respuesta correcta es enojo, la respuesta más común de los pacientes es miedo.


Assuntos
Doença de Alzheimer/psicologia , Emoções , Reconhecimento Facial , Idoso , Idoso de 80 Anos ou mais , Humanos
20.
Phys Rev Lett ; 123(3): 031301, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31386454

RESUMO

ANAIS is a direct detection dark matter experiment aiming at the testing of the DAMA/LIBRA annual modulation result, which, for about two decades, has neither been confirmed nor ruled out by any other experiment in a model independent way. ANAIS-112, consisting of 112.5 kg of sodium iodide crystals, has been taking data at the Canfranc Underground Laboratory, Spain, since August 2017. This Letter presents the annual modulation analysis of 1.5 years of data, amounting to 157.55 kg yr. We focus on the model independent analysis searching for modulation and the validation of our sensitivity prospects. ANAIS-112 data are consistent with the null hypothesis (p values of 0.67 and 0.18 for [2-6] and [1-6] keV energy regions, respectively). The best fits for the modulation hypothesis are consistent with the absence of modulation (S_{m}=-0.0044±0.0058 cpd/kg/keV and -0.0015±0.0063 cpd/kg/keV, respectively). They are in agreement with our estimated sensitivity for the accumulated exposure, which supports our projected goal of reaching a 3σ sensitivity to the DAMA/LIBRA result in five years of data taking.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA