674 research outputs found
Comparison of Fermi-LAT and CTA in the region between 10-100 GeV
The past decade has seen a dramatic improvement in the quality of data
available at both high (HE: 100 MeV to 100 GeV) and very high (VHE: 100 GeV to
100 TeV) gamma-ray energies. With three years of data from the Fermi Large Area
Telescope (LAT) and deep pointed observations with arrays of Cherenkov
telescope, continuous spectral coverage from 100 MeV to TeV exists for
the first time for the brightest gamma-ray sources. The Fermi-LAT is likely to
continue for several years, resulting in significant improvements in high
energy sensitivity. On the same timescale, the Cherenkov Telescope Array (CTA)
will be constructed providing unprecedented VHE capabilities. The optimisation
of CTA must take into account competition and complementarity with Fermi, in
particularly in the overlapping energy range 10100 GeV. Here we compare the
performance of Fermi-LAT and the current baseline CTA design for steady and
transient, point-like and extended sources.Comment: Accepted for Publication in Astroparticle Physic
A Development Environment for Visual Physics Analysis
The Visual Physics Analysis (VISPA) project integrates different aspects of
physics analyses into a graphical development environment. It addresses the
typical development cycle of (re-)designing, executing and verifying an
analysis. The project provides an extendable plug-in mechanism and includes
plug-ins for designing the analysis flow, for running the analysis on batch
systems, and for browsing the data content. The corresponding plug-ins are
based on an object-oriented toolkit for modular data analysis. We introduce the
main concepts of the project, describe the technical realization and
demonstrate the functionality in example applications
Ampliación del primer catálogo Astrolabio de San Juan, programa catálogo
In order to enlarge the First Catalogue of the San Juan Astrolabe a special program, called "Catalogue Program" has been made. It will permit to compute corrections Δα and Δδ for 180 stars from the FK4 and FK4 supplement.Asociación Argentina de Astronomí
Assessment of the Fitbit Charge 2 for monitoring heart rate
Fitness trackers are devices or applications for monitoring and tracking fitness-related metrics such as distance walked or run, calorie consumption, quality of sleep and heart rate. Since accurate heart rate monitoring is essential in fitness training, the objective of this study was to assess the accuracy and precision of the Fitbit Charge 2 for measuring heart rate with respect to a gold standard electrocardiograph. Fifteen healthy participants were asked to ride a stationary bike for 10 minutes and their heart rate was simultaneously recorded from each device. Results showed that the Fitbit Charge 2 underestimates the heart rate. Although the mean bias in measuring heart rate was a modest -5.9 bpm (95% CI: -6.1 to -5.6 bpm), the limits of agreement, which indicate the precision of individual measurements, between the Fitbit Charge 2 and criterion measure were wide (+16.8 to -28.5 bpm) indicating that an individual heart rate measure could plausibly be underestimated by almost 30 bpm
Resultados provisorios de las correcciones Δα y Δδ de 100 estrellas del programa de catálogo observadas con astrolabio del O.A.F.A.
Se presentan resultados provisorios en la determinación de correcciones Δα y Δδ de 100 estrellas del FK4 y FK4 Suplementario, observadas con astrolabio en los años 1975/6 por medio de los grupos Especiales del Catálogo. Se comparan los resultados con los obtenidos en Sgo. de Chile con instrumento similar.Asociación Argentina de Astronomí
Gamma-ray signatures of cosmic ray acceleration, propagation, and confinement in the era of CTA
Galactic cosmic rays are commonly believed to be accelerated at supernova
remnants via diffusive shock acceleration. Despite the popularity of this idea,
a conclusive proof for its validity is still missing. Gamma-ray astronomy
provides us with a powerful tool to tackle this problem, because gamma rays are
produced during cosmic ray interactions with the ambient gas. The detection of
gamma rays from several supernova remnants is encouraging, but still does not
constitute a proof of the scenario, the main problem being the difficulty in
disentangling the hadronic and leptonic contributions to the emission. Once
released by their sources, cosmic rays diffuse in the interstellar medium, and
finally escape from the Galaxy. The diffuse gamma-ray emission from the
Galactic disk, as well as the gamma-ray emission detected from a few galaxies
is largely due to the interactions of cosmic rays in the interstellar medium.
On much larger scales, cosmic rays are also expected to permeate the
intracluster medium, since they can be confined and accumulated within clusters
of galaxies for cosmological times. Thus, the detection of gamma rays from
clusters of galaxies, or even upper limits on their emission, will allow us to
constrain the cosmic ray output of the sources they contain, such as normal
galaxies, AGNs, and cosmological shocks. In this paper, we describe the impact
that the Cherenkov Telescope Array, a future ground-based facility for
very-high energy gamma-ray astronomy, is expected to have in this field of
research.Comment: accepted to Astroparticle Physics, special issue on Physics with the
Cherenkov Telescope Arra
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Acute study of dose-dependent effects of (-)-epicatechin on vascular function in healthy male volunteers: a randomized controlled trial
BACKGROUND & AIMS
There is convincing clinical evidence to suggest that flavanol-containing foods/beverages are capable of inducing improvements in human vascular function. However, whilst (-)-epicatechin has been tested for efficacy, a full dose-dependency has yet to be established, particularly at doses below 1 mg/kg BW. The current study examined the dose-dependent effects of (-)-epicatechin on human vascular function with concurrent measurement of plasma (-)-epicatechin metabolites and levels of circulating nitrite and nitrate species, NOx.
METHODS
An acute, double-blind, placebo-controlled, crossover intervention trial was conducted in 20 healthy males with 4 treatment arms: water-based (-)-epicatechin (0.1, 0.5 and 1.0 mg/kg BW) and a water only as control. Vascular function was assessed by flow-mediated dilatation (FMD) measured at the brachial artery, laser Doppler imaging with iontophoresis (LDI) at the subcutaneous capillaries of the forearm (response to Ach and SNP) and peripheral blood pressure (BP) at baseline, 1, 2, 4 and 6 h post-intervention. Plasma analysis of epicatechin metabolites was conducted by LC-MS and circulating plasma of nitrite and nitrate species were performed using an HPLC-based system (ENO-30).
RESULTS
Significant increases in % FMD were found to occur at 1 and 2 h following intake of 1 mg/kg BW, and at 2 h for the 0.5 mg/kg BW intake. There were no significant changes in LDI or BP at any time-points or intake levels. Increases in FMD over the 6 h timeframe were closely paralleled by the appearance of total plasma (-)-epicatechin metabolites. Non-significant changes in circulating NOx was observed.
CONCLUSIONS
Our data add further evidence that (-)-epicatechin is a causal vasoactive molecule within flavanol-containing foods/beverages. In addition, we show for the first time that intake levels as low as 0.5 mg/kg BW are capable of inducing acute improvements in vascular function (FMD) in healthy volunteers
Observaciones de Urano con el astrolabio de San Juan
Se dan los resultados provisorios de las correcciones Δα y Δδ a las coordenadas ecuatoriales del planeta Urano, basadas en las observaciones realizadas en tres campañas sucesivas, (1979, 1980 y 1981). Estos resultados fueron derivados de 77 pasajes del planeta al Este y Oeste de las cuales 22 son dobles.Asociación Argentina de Astronomí
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