17,531 research outputs found
Solar Irradiance Observed from PVO and Inferred Solar Rotation
Solar irradiance in the extreme ultraviolet flux (EUV) has been monitored for 11 years by the Pioneer Venus Orbiter (PVO). Since the experiment moves around the Sun with the orbital rate of Venus rather than that of Earth, the measurement gives us a second viewing location from which to begin unravelling which irradiance variations are intrinsic to the Sun, and which are merely rotational modulations whose periods depend on the motion of the observer. Researchers confirm an earlier detection, made with only 8.6 years of data, that the EUV irradiance is modulated by rotation rates of two families of global oscillation modes. One family is assumed to be r-modes occupying the convective envelope and sharing its rotation, while the other family (g-modes) lies in the radiative interior which as a slower rotation. Measured power in r-modes of low angular harmonic number indicates that the Sun's envelope rotated about 0.7 percent faster near the last solar maximum (1979 thru 1982) than it did during the next rise to maximum (1986 to 1989). No change was seen in the g-mode family of lines, as would be expected from the much greater rotational inertia of the radiative interior
Diffusion and Home Range Parameters for Rodents: Peromyscus maniculatus in New Mexico
We analyze data from a long term field project in New Mexico, consisting of
repeated sessions of mark-recaptures of Peromyscus maniculatus (Rodentia:
Muridae), the host and reservoir of Sin Nombre Virus (Bunyaviridae:
Hantavirus). The displacements of the recaptured animals provide a means to
study their movement from a statistical point of view. We extract two
parameters from the data with the help of a simple model: the diffusion
constant of the rodents, and the size of their home range. The short time
behavior shows the motion to be approximately diffusive and the diffusion
constant to be 470+/-50m^2/day. The long time behavior provides an estimation
of the diameter of the rodent home ranges, with an average value of 100+/-25m.
As in previous investigations directed at Zygodontomys brevicauda observations
in Panama, we use a box model for home range estimation. We also use a harmonic
model in the present investigation to study the sensitivity of the conclusions
to the model used and find that both models lead to similar estimates.Comment: The published paper in Ecol. Complexity has an old version of Figure
6. Here we have put the correct version of Figure
Finite Size Analysis of the U(1) Background Field Effective Action
We apply the finite size scaling analysis to the derivative of the density of
the effective action for the lattice U(1) pure gauge theory in an external
constant magnetic field. We found the presence of a continuous phase
transition. Moreover, our extimate of of the critical parameters gives values
consistent with those extracted from the analysis of the specific heat.Comment: LaTeX2e, 12 pages (5 figures
Eclipse Timings of the Transient Low Mass X-ray Binary EXO0748-676. IV. The Rossi X-Ray Timing Explorer Eclipses
We report our complete database of X-ray eclipse timings of the low mass
X-ray binary EXO0748-676 observed by the Rossi X-Ray Timing Explorer (RXTE)
satellite. As of this writing we have accumulated 443 full X-ray eclipses, 392
of which have been observed with the Proportional Counter Array on RXTE. These
include both observations where an eclipse was specifically targeted and those
eclipses found in the RXTE data archive. Eclipse cycle count has been
maintained since the discovery of the EXO0748-676 system in February 1985. We
describe our observing and analysis techniques for each eclipse and describe
improvements we have made since the last compilation by Wolff et al. (2002).
The principal result of this paper is the database containing the timing
results from a seven-parameter fit to the X-ray light curve for each observed
eclipse along with the associated errors in the fitted parameters. Based on the
standard O-C analysis, EXO0748-676 has undergone four distinct orbital period
epochs since its discovery. In addition, EXO0748-676 shows small-scale events
in the O-C curve that are likely due to short-lived changes in the secondary
star.Comment: Accepted for publication in The Astrophysical Journal Supplement
Series, 5 figures. Analysis revised. Tables 1 & 3 update
Phase randomisation: a convergence diagnostic test for MCMC
Most MCMC users address the convergence problem by applying diagnostic tools to the output produced by running their samplers. Potentially useful diagnostics may be borrowed from diverse areas such as time series. One such method is phase randomisation. The aim of this paper is to describe this method in the context of MCMC, summarise its characteristics, and contrast its performance with those of the more common diagnostic tests for MCMC. It is observed that the new tool contributes information about third and higher order cumulant behaviour which is important in characterising certain forms of nonlinearity and nonstationarity.Convergence diagnostics; higher cumulants; Markov Chain Monte Carlo; non-linear time series; stationarity; surrogate series
Apicultura sustentável na propriedade familiar de base ecológica.
bitstream/item/30823/1/Circular-64.pdfMerta: 2008
Alimentação artificial estimulante em apicultura sustentável.
bitstream/item/44096/1/folder-alimentacao-artificial.pd
Captura de enxames em vôo ou recém-pousados para apicultura sustentável.
bitstream/item/44187/1/CAPTURA-DE-ENXAME.pd
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