7,178 research outputs found
On the properties of the RHESSI intermediate-duration gamma-ray bursts
The intermediate-duration gamma-ray bursts (GRBs) identified in the data of
the RHESSI satellite are investigated with respect to their spectral lags, peak
count rates, redshifts, supernova observations, and star formation rates of
their host galaxies. Standard statistical tests like Kolmogorov-Smirnov and
Student t-test are used. It is discussed whether these bursts belong to the
group of so-called short or long GRBs, or if they significantly differ from
both groups.Comment: 4 pages, 4 figures, 2 table
Comparación de dos tablas demográficas: aproximación a su significación estadística
En este trabajo se analiza la significación estadística de la posible igualdad de dos tablas demográficas. Concretamente, se presenta la aplicabilidad de un clásico contraste de los métodos estadísticos -el de homogeneidad de dos distribuciones- para contrastar la hipótesis nula "H0 = las dos tablas demográficas son iguales, esto es, responden a una misma estructura del fenómeno demográfico estudiado", frente a la alternativa que niega la anterior. Ambas tablas se refieren a un único fenómeno demográfico para el mismo ámbito territorial y dos momentos diferentes de tiempo (contraste temporal), o para la misma referencia temporal en dos poblaciones de ámbito territorial distinto (contraste territorial). Se aplica la metodología descrita en dos situaciones: para la comparación de los niveles de mortalidad de dos provincias, y sobre dos tablas tipo correspondientes a sendos niveles de mortalidad
EL MODELO TABULAR EN DEMOGRAFÍA: UNA LECTURA INPUT-OUTPUT
The analytical model scheme known as "demographic table" permits to measure the influence that on an only demographic phenomenon has the time, understood this as "duration or age". The present work uses the analysis input-output technique to explain the existing relationships in a demographic table, enriching the conclusions that they can obtain of it and permitting to establish the relationship between the time-calendar and the time-duration. Also it is defined a measure to value the difference between two different demographic tables - referred to moments or to different populations - to the time of describing the incidence of the same demographic phenomenon. It is applied the I/O methodology exposed to a concrete table, corresponding to the marriage of the Spanish women in the period 1956-65, while model life tables are used to illustrate the measurement of the differences between them. El esquema del modelo analítico conocido como "tabla demográfica" permite medir la influencia que sobre un único fenómeno demográfico tiene el tiempo, entendido éste como "duración o edad". El presente trabajo utiliza la técnica del análisis input-output para explicar las relaciones existentes en una tabla demográfica, enriqueciendo las conclusiones que pueden extraerse de ella y permitiendo establecer la relación entre el tiempo-calendario y el tiempo-duración. También se define una medida para valorar la diferencia entre dos tablas demográficas diferentes - referidas a momentos o a poblaciones distintas - a la hora de describir la incidencia del mismo fenómeno demográfico. Se aplica la metodología I/O expuesta a una tabla concreta, correspondiente a la nupcialidad de las mujeres españolas en el período 1956-65, mientras que las tablas-tipo de mortalidad son utilizadas para ilustrar la medición de las diferencias entre ellas.calendario, coeficientes técnicos, demanda final, intensidad, matriz inversa, mortalidad, nupcialidad, output total, tabla demográfica, tabla input-output. calendar, technical coefficients, final demand, intensity, inverse matrix, mortality, marriage, total output, demographic table, input-output table.
Symbiotic relationship between robots - a ROS ARDrone/YouBot library
A Symbiotic relationship between robots is theoretically developed. It is characterised by sharing sensory information and tightly coordinating operational logic by taking care of each other’s needs during missions. The system is characterised by an intertwined reasoning system while having separate conditioning and execution of plans to achieve subgoals to support each other. The results are illustrated on strong operational inter-dependence of a rover and a drone through shared logical inference. The drone uses the rover as a landing pad and the rover uses the drone to complements its sensor system by information gathering. There is a GitHub library provided in association with the demonstration for generic use of adding cameras and cooperation logic to a AR.Drone 2.0 and a KUKA youBot system. The benefits of symbiotic relationship are quantitatively evaluated on the demonstration example
The compact radio structure of the high-redshift blazar J1430+4204 before and after a major outburst
The high-redshift (z=4.72) blazar J1430+4204 produced an exceptional radio
outburst in 2006. We analyzed 15-GHz radio interferometric images obtained with
the Very Long Baseline Array (VLBA) before and after the outburst, to search
for possible structural changes on milli-arcsecond angular scales and to
determine physical parameters of the source.Comment: Proceedings of the 5th Workshop of Young Researchers in Astronomy and
Astrophysics, Budapest, 2009; to be published in J. Phys.: Conf. Series
(JPCS); 4 pages, 3 figure
Characterization of biomass burning emissions from cooking fires, peat, crop residue, and other fuels with high-resolution proton-transfer-reaction time-of-flight mass spectrometry
We deployed a high-resolution proton-transferreaction time-of-flight mass spectrometer (PTR-TOF-MS) to measure biomass-burning emissions from peat, crop residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experiment (FLAME-4) laboratory campaign. A combination of gas standard calibrations and composition sensitive, mass-dependent calibration curves was applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign the best identities to most major “exact masses”, including many high molecular mass species. Using these methods, approximately 80–96% of the total NMOC mass detected by the PTR-TOFMS and Fourier transform infrared (FTIR) spectroscopy was positively or tentatively identified for major fuel types. We report data for many rarely measured or previously unmeasured emissions in several compound classes including aromatic hydrocarbons, phenolic compounds, and furans; many of these are suspected secondary organic aerosol precursors. A large set of new emission factors (EFs) for a range of globally significant biomass fuels is presented. Measurements show that oxygenated NMOCs accounted for the largest fraction of emissions of all compound classes. In a brief study of various traditional and advanced cooking methods, the EFs for these emissions groups were greatest for open threestone cooking in comparison to their more advanced counterparts. Several little-studied nitrogen-containing organic compounds were deteched from many fuel types, that together accounted for 0.1-8.7% of the fuel nitrogen, and some may play a role in new particle formation
Searching for galactic sources in the Swift GRB catalog
Since the early 1990s Gamma Ray Bursts have been accepted to be of
extra-galactic origin due to the isotropic distribution observed by BATSE and
the redshifts observed via absorption line spectroscopy. Nevertheless, upon
further examination at least one case turned out to be of galactic origin. This
particular event presented a Fast Rise, Exponential Decay (FRED) structure
which leads us to believe that other FRED sources might also be Galactic. This
study was set out to estimate the most probable degree of contamination by
galactic sources that certain samples of FREDs have. In order to quantify the
degree of anisotropy the average dipolar and quadripolar moments of each sample
of GRBs with respect to the galactic plane were calculated. This was then
compared to the probability distribution of simulated samples comprised of a
combination of isotropically generated sources and galactic sources. We observe
that the dipolar and quadripolar moments of the selected subsamples of FREDs
are found more than two standard deviations outside those of random
isotropically generated samples.The most probable degree of contamination by
galactic sources for the FRED GRBs of the Swift catalog detected until February
2011 that do not have a known redshift is about 21 out of 77 sources which is
roughly equal to 27%. Furthermore we observe, that by removing from this sample
those bursts that may have any type of indirect redshift indicator and multiple
peaks gives the most probable contamination increases up to 34% (17 out of 49
sources). It is probable that a high degree of contamination by galactic
sources occurs among the single peak FREDs observed by Swift.Comment: Published to A&A, 4 pages, 5 figures, this arXiv version includes
appended table with all the bursts considered in this stud
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