Improving photon-hadron discrimination based on cosmic ray surface detector data

The search for photons at EeV energies and beyond has considerable astrophysical interest and will remain one of the key challenges for ultra-high energy cosmic ray (UHECR) observatories in the near future. Several upper limits to the photon flux have been established since no photon has been unambiguously observed up to now. An improvement in the reconstruction efficiency of the photon showers and/or better discrimination tools are needed to improve these limits apart from an increase in statistics. Following this direction, we analyze in this work the ability of the surface parameter Sb, originally proposed for hadron discrimination, for photon search. Semi-analytical and numerical studies are performed in order to optimize Sb for the discrimination of photons from a proton background in the energy range from 10^18.5 to 10^19.6 eV. Although not shown explicitly, the same analysis has been performed for Fe nuclei and the corresponding results are discussed when appropriate. The effects of different array geometries and the underestimation of the muon component in the shower simulations are analyzed, as well as the Sb dependence on primary energy and zenith angle.Comment: 9 pages, 19 Figures. Accepted in Astroparticle Physics on May 31th, 201

Microbiota intestinal e câncer

Microbiota is defined as the group of microorganisms present in several places in the body. Those found in the intestine play an essential role due to the close relationship they have with health and disease, and particularly with cancer. Knowing which microorganisms populate the gastrointestinal tract, their functions, the effects of altering their composition, as well as identifying the relationship between a healthy microbiota and the prevention of tumor development, or how its alteration is linked to tumor development, deserves special attention. The gut microbiota is perceived as a key element piece in the treatment of cancer.La microbiota es el conjunto de microorganismos localizado en diferentes sitios del cuerpo. Aquellos que se encuentran en el intestino tienen un rol esencial, debido a la estrecha relación que tienen con la salud y la enfermedad, en especial el cáncer. Conocer qué microorganismos pueblan el tracto gastrointestinal y sus funciones, qué ocurre cuando se altera su composición, así como identificar su relación con una microbiota saludable para la prevención del desarrollo de tumores, o cómo se vincula la alteración de la microbiota con el desarrollo de tumores merece especial atención.A microbiota é o conjunto de microrganismos localizados em diferentes partes do corpo. Aqueles que estão no intestino têm um papel essencial, devido à estreita relação que mantêm com a saúde e a doença, principalmente o câncer. Saber quais microrganismos habitam o trato gastrointestinal, suas funções, o que acontece quando sua composição é alterada, bem como identificar sua relação com uma microbiota saudável para a prevenção do desenvolvimento de tumores, ou como sua alteração está ligada ao desenvolvimento dos mesmos, merece atenção especial

Genetic diagnosis of α1-antitrypsin deficiency using DNA from buccal swab and serum samples

Background: α1-Antitrypsin deficiency (AATD) is associated with a high risk of developing lung and liver disease. Despite being one of the most common hereditary disorders worldwide, AATD remains under-diagnosed and prolonged delays in diagnosis are usual. The aim of this study was to validate the use of buccal swab samples and serum circulating DNA for the complete laboratory study of AATD. Methods: Sixteen buccal swab samples from previously characterized AATD patients were analyzed using an allele-specific genotyping assay and sequencing method. In addition, 19 patients were characterized by quantification, phenotyping and genotyping using only serum samples. Results: the 16 buccal swab samples were correctly characterized by genotyping. Definitive results were obtained in the 19 serum samples analyzed by quantification, phenotyping and genotyping, thereby performing the complete AATD diagnostic algorithm. Conclusions: Buccal swab samples may be useful to expand AATD screening programs and family studies. Genotyping using DNA from serum samples permits the application of the complete diagnostic algorithm without delay. These two methods will be useful for obtaining more in depth knowledge of the real prevalence of patients with AATD

A pandemia do COVID-19: fome, desnutrição e consequências sociais para a América Latina e o Caribe

El 11 de marzo de 2020, la Organización Mundial de la Salud anunció que la enfermedad conocida como COVID-19 reunía las condiciones para alcanzar el estatus de pandemia.  Muy distantes estábamos entonces de percibir, sin embargo, la gravedad de esta palabra, que se tradujo, rápidamente, en una terrible crisis sanitaria, causante del colapso de las redes de atención de salud, el fallecimiento masivo de personal médico de primera línea, y un aumento en la tasa de mortalidad de la población difícil de controlar

Imaging Atmospheric Cherenkov Telescopes pointing determination using the trajectories of the stars in the field of view

38th International Cosmic Ray Conference (ICRC2023), 26 July - 3 August, 2023, Nagoya, Japan.Mykhailo Dalchenko and Matthieu Heller on behalf of the CTA-LST Project. Luis del Peral Gochicoa, Jose Julio Lozano Bahilo and Maria Dolores Rodriguez Frias belong to the CTA-LST Project.We present a new approach to the pointing determination of Imaging Atmospheric Cherenkov Telescopes (IACTs). This method is universal and can be applied to any IACT with minor modifications. It uses the trajectories of the stars in the field of view of the IACT’s main camera and requires neither dedicated auxiliary hardware nor a specific data taking mode. The method consists of two parts: firstly, we reconstruct individual star positions as a function of time, taking into account the point spread function of the telescope; secondly, we perform a simultaneous fit of all reconstructed star trajectories using the orthogonal distance regression method. The method does not assume any particular star trajectories, does not require a long integration time, and can be applied to any IACT observation mode. The performance of the method is assessed with commissioning data of the Large-Sized Telescope prototype (LST-1), showing the method’s stability and remarkable pointing performance of the LST-1 telescope

Ultra-deep pyrosequencing analysis of the hepatitis B virus preCore region and main catalytic motif of the viral polymerase in the same viral genome

Hepatitis B virus (HBV) pregenomic RNA contains a hairpin structure (ϵ) located in the preCore region, essential for viral replication. ϵ stability is enhanced by the presence of preCore variants and ϵ is recognized by the HBV polymerase (Pol). Mutations in the retrotranscriptase domain (YMDD) of Pol are associated with treatment resistance. The aim of this study was to analyze the preCore region and YMDD motif by ultra-deep pyrosequencing (UDPS). To evaluate the UDPS error rate, an internal control sequence was inserted in the amplicon. A newly developed technique enabled simultaneous analysis of the preCore region and Pol in the same viral genome, as well as the conserved sequence of the internal control. Nucleotide errors in HindIII yielded a UDPS error rate <0.05%. UDPS study confirmed the possibility of simultaneous detection of preCore and YMDD mutations, and demonstrated the complexity of the HBV quasispecies and cooperation between viruses. Thermodynamic stability of the ϵ signal was found to be the main constraint for selecting main preCore mutations. Analysis of ϵ-signal variability suggested the essential nature of the ϵ structural motif and that certain nucleotides may be involved in ϵ signal functions

Application of a diagnostic algorithm for the rare deficient variant Mmalton of alpha-1-antitrypsin deficiency: a new approach

Background and objectives: alpha-1-antitrypsin deficiency (AATD) is associated with a high risk for the development of early-onset emphysema and liver disease. A large majority of subjects with severe AATD carry the ZZ genotype, which can be easily detected. Another rare pathologic variant, the Mmalton allele, causes a deficiency similar to that of the Z variant, but it is not easily recognizable and its detection seems to be underestimated. Therefore, we have included a rapid allele-specific genotyping assay for the detection of the Mmalton variant in the diagnostic algorithm of AATD used in our laboratory. The objective of this study was to test the usefulness of this new algorithm for Mmalton detection. Materials and methods: we performed a retrospective revision of all AATD determinations carried out in our laboratory over 2 years using the new diagnostic algorithm. Samples with a phenotype showing one or two M alleles and AAT levels discordant with that phenotype were analyzed using the Mmalton allele-specific genotyping assay. Results: we detected 49 samples with discordant AAT levels; 44 had the MM and five the MS phenotype. In nine of these samples, a single rare Mmalton variant was detected. During the study period, two family screenings were performed and four additional Mmalton variants were identified. Conclusion: the incorporation of the Mmalton allele-specific genotyping assay in the diagnostic algorithm of AATD resulted in a faster and cheaper method to detect this allele and avoided a significant delay in diagnosis when a sequencing assay was required. This methodology can be adapted to other rare variants. Standardized algorithms are required to obtain conclusive data of the real incidence of rare AAT alleles in each region