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

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

Fanconi anemia cells with unrepaired DNA damage activate components of the checkpoint recovery process

International audienceBACKGROUND:The FA/BRCA pathway repairs DNA interstrand crosslinks. Mutations in this pathway cause Fanconi anemia (FA), a chromosome instability syndrome with bone marrow failure and cancer predisposition. Upon DNA damage, normal and FA cells inhibit the cell cycle progression, until the G2/M checkpoint is turned off by the checkpoint recovery, which becomes activated when the DNA damage has been repaired. Interestingly, highly damaged FA cells seem to override the G2/M checkpoint. In this study we explored with a Boolean network model and key experiments whether checkpoint recovery activation occurs in FA cells with extensive unrepaired DNA damage.METHODS:We performed synchronous/asynchronous simulations of the FA/BRCA pathway Boolean network model. FA-A and normal lymphoblastoid cell lines were used to study checkpoint and checkpoint recovery activation after DNA damage induction. The experimental approach included flow cytometry cell cycle analysis, cell division tracking, chromosome aberration analysis and gene expression analysis through qRT-PCR and western blot.RESULTS:Computational simulations suggested that in FA mutants checkpoint recovery activity inhibits the checkpoint components despite unrepaired DNA damage, a behavior that we did not observed in wild-type simulations. This result implies that FA cells would eventually reenter the cell cycle after a DNA damage induced G2/M checkpoint arrest, but before the damage has been fixed. We observed that FA-A cells activate the G2/M checkpoint and arrest in G2 phase, but eventually reach mitosis and divide with unrepaired DNA damage, thus resolving the initial checkpoint arrest. Based on our model result we look for ectopic activity of checkpoint recovery components. We found that checkpoint recovery components, such as PLK1, are expressed to a similar extent as normal undamaged cells do, even though FA-A cells harbor highly damaged DNA.CONCLUSIONS:Our results show that FA cells, despite extensive DNA damage, do not loss the capacity to express the transcriptional and protein components of checkpoint recovery that might eventually allow their division with unrepaired DNA damage. This might allow cell survival but increases the genomic instability inherent to FA individuals and promotes cancer

Response to comment on 'Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity'

Lambert et al. question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 amphibian species

Highlights from the Pierre Auger Observatory

The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a number of major breakthroughs. Among these we discuss the energy spectrum and the searches for large-scale anisotropies. We present analyses of our X$_{max}$ data and show how it can be interpreted in terms of mass composition. We also describe some new analyses that extract mass sensitive parameters from the 100% duty cycle SD data. A coherent interpretation of all these recent results opens new directions. The consequences regarding the cosmic ray composition and the properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray Conference, Rio de Janeiro 201

Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{$6\times 10^{19}$eV}. The anisotropy was measured by the fraction of arrival directions that are less than $3.1^\circ$ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron $12^{\rm th}$ catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is $(38^{+7}_{-6})$, compared with $21$ expected for isotropic cosmic rays. This is down from the early estimate of $(69^{+11}_{-13})$. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 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