5,332 research outputs found
Data-Driven Prediction of Thresholded Time Series of Rainfall and SOC models
We study the occurrence of events, subject to threshold, in a representative
SOC sandpile model and in high-resolution rainfall data. The predictability in
both systems is analyzed by means of a decision variable sensitive to event
clustering, and the quality of the predictions is evaluated by the receiver
operating characteristics (ROC) method. In the case of the SOC sandpile model,
the scaling of quiet-time distributions with increasing threshold leads to
increased predictability of extreme events. A scaling theory allows us to
understand all the details of the prediction procedure and to extrapolate the
shape of the ROC curves for the most extreme events. For rainfall data, the
quiet-time distributions do not scale for high thresholds, which means that the
corresponding ROC curves cannot be straightforwardly related to those for lower
thresholds.Comment: 19 pages, 10 figure
GALEX measurements of the Big Blue Bump as a tool to study bolometric corrections in AGNs
Active Galactic Nuclei emit over the entire electromagnetic spectrum with the
peak of the accretion disk emission in the far-UV, a wavelength range
historically difficult to investigate. We use here the GALEX (Galaxy Evolution
Explorer) Near-UV and Far-UV measurements (complemented with optical data from
Sloan Digital Sky Survey (SDSS) and XMM-Newton X-ray spectra) of a sample of 83
X-ray selected type 1 AGN extracted from the XMM-Newton Bright Serendipitous
Survey to study their spectral energy distribution (SED) in the optical, Near
and Far-UV and X-ray energy bands. We have constrained the luminosity of the
accretion disk emission component and calculated the hard X-ray bolometric
corrections for a significant sample of AGN spanning a large range in
properties (z, L(x)).Comment: 2 pages, 2 figures, To appear in refereed Proceedings of "X-ray
Astronomy 2009: Present Status, Multi-Wavelength Approach and Future
Perspectives", Bologna, Italy, September 7-11, 2009, AIP, eds. A. Comastri,
M. Cappi, and L. Angelin
Anomalous Transport in Conical Granular Piles
Experiments on 2+1-dimensional piles of elongated particles are performed.
Comparison with previous experiments in 1+1 dimensions shows that the addition
of one extra dimension to the dynamics changes completely the avalanche
properties, appearing a characteristic avalanche size. Nevertheless, the time
single grains need to cross the whole pile varies smoothly between several
orders of magnitude, from a few seconds to more than 100 hours. This behavior
is described by a power-law distribution, signaling the existence of scale
invariance in the transport process.Comment: Accepted in PR
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PPAR gamma pro12Ala polymorphism and type 2 diabetes: a study in a spanish cohort
Type 2 diabetes (T2D) is a disease whose occurrence is increasing prevalent in westernized civilizations and is responsible for the proliferation in the morbidity and total mortality of patients with cardiovascular diseases, worldwide. However, the complexity in the treatment and prevention of T2D arises from the intricacy of the many physical and biological factors involved in its etiology. Impaired pathways for insulin signaling have been implicated as one the many factors in the development of T2D Individual peroxisome proliferator-activated receptors (PPARs) have previously exhibited associations with alterations of lipid profiles, fat tissue and T2D and displayed complications derived from high levels of glucose. However, PPARgamma has not yet been associated with the development or developmental pathways of T2D. We performed an observational study a Spanish cohort in order to better understand the association between the SNP PPARgamma polymorphism Pro12Ala in our patients and the incidence of T2D and other cardiovascular complications. We study did not find a statistically significant relationship between the Pro12Ala and T2D development in our cohort, future observations will help us to know the association with vascular disease in patients with T2D
Las mineralizaciones de Sn-Ti del borde occidental de la Cuenca de Ciudad Rodrigo
[Resumen] El borde Occidental de la Cuenca Terciaria de Ciudad Rodrigo presenta una serie de mineralizaciones de Sn y Ti, que han sido objeto de laboreo en varias ocasiones durante el presente siglo existiendo en la actualidad dos explotaciones de cierta importancia; una en Puebla de Azaba (Salamanca) y otra en Nave de Haver (Portugal). Los materiales detríticos en los que se encuentran la casiterita y la ilmenita proceden de la denudación del batolito de Guarda, que presenta facies leucograníticas con contenidos de estaño superiores a 500 ppm, y del desmantelamiento de su cortejo filoniano. Estas formaciones con contenidos de Sn muy irregulares, pero con valores generalmente inferiores a 200 ppm, son considerados como dep6sitos Deluviales. Las minas activas benefician fundamentalmente los aluviones recientes, que alcanzan contenidos de hasta 800 ppm de estaño[Abstract] Western borderland of the Ciudad Rodrigo Tertiary Basin bears a suite of Sn-Ti deposits that were mined for several times in this century. Nowadays, two relatively important mines occur in that zone: Puebla de Azaba (Salamanca) and Nave de Haver (Portugal) . -Detrital sediments with casiterite and ilmenite como from denudation of Guarda batholith, which present leuco granite facies with Sn contents up to 500 ppm. The detrital formatión, with variable Sn contents, generally less than 200 ppm, is considered as a "Deluvial" facies. Active mining focusses on recent alluvials whose Sn contents reach up 5OO ppm
Network of Earthquakes and Recurrences Therein
We quantify the correlation between earthquakes and use the same to
distinguish between relevant causally connected earthquakes. Our correlation
metric is a variation on the one introduced by Baiesi and Paczuski (2004). A
network of earthquakes is constructed, which is time ordered and with links
between the more correlated ones. Data pertaining to the California region has
been used in the study. Recurrences to earthquakes are identified employing
correlation thresholds to demarcate the most meaningful ones in each cluster.
The distribution of recurrence lengths and recurrence times are analyzed
subsequently to extract information about the complex dynamics. We find that
the unimodal feature of recurrence lengths helps to associate typical rupture
lengths with different magnitude earthquakes. The out-degree of the network
shows a hub structure rooted on the large magnitude earthquakes. In-degree
distribution is seen to be dependent on the density of events in the
neighborhood. Power laws are also obtained with recurrence time distribution
agreeing with the Omori law.Comment: 17 pages, 5 figure
Higgs Boson Phenomenology in a Simple Model with Vector Resonances
In this paper we consider a simple scenario where the Higgs boson and two
vector resonances are supposed to arise from a new strong interacting sector.
We use the ATLAS measurements of the dijet spectrum to set limits on the masses
of the resonances. Additionally we compute the Higgs boson decay to two photons
and found, when compare to the Standard Model prediction, a small excess which
is compatible with ATLAS measurements. Finally we make prediction for
Higgs-strahlung processes for the LHC running at 14 TeV
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