1,211 research outputs found
Assessing strength and power in resistance training
Maximal Dynamic Strength is usually assessed either by the one repetition maximum test (1-RM) or by a repetition maximum test with submaximal loads, which requires the application of a formula to estimate the value of 1-RM. This value is needed to establish the objective of resistance training: such as maximum strength, endurance strength, and/or explosive strength. However, both 1-RM and submaximal tests are unable to highlight the changes produced on power and velocity. This manuscript summarizes and reviews several common strength testing protocols and proposes a novel approach that may offer greater insight to hierarchical muscle functionalit
An equatorial ultra iron-poor star identified in BOSS
We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor red
giant star ([Fe/H] ~ -4.3) with a very high carbon abundance ([C/Fe]~ +2.5).
This object is the fifth star in this rare class, and the combination of a
fairly low effective temperature (Teff ~ 5300 K), which enhances line
absorption, with its brightness (g=16.9), makes it possible to measure the
abundances of calcium, carbon and iron using a low-resolution spectrum from the
Sloan Digital Sky Survey. We examine the carbon and iron abundance ratios in
this star and other similar objects in the light of predicted yields from
metal-free massive stars, and conclude that they are consistent. By way of
comparison, stars with similarly low iron abundances but lower carbon-to-iron
ratios deviate from the theoretical predictions.Comment: 6 pages, 4 figures, accepted for publication in A&
Natural history of a visceral leishmaniasis outbreak in highland Ethiopia
In May 2005, visceral leishmaniasis (VL) was recognized for the first time in Libo Kemken, Ethiopia, a highland region where only few cases had been reported before. We analyzed records of VL patients treated from May 25, 2005 to December 13, 2007 by the only VL treatment center in the area, maintained by Médecins Sans Frontières-Ethiopia, Operational Center Barcelona-Athens. The median age was 18 years; 77.6% were male. The overall case fatality rate was 4%, but adults 45 years or older were five times as likely to die as 5-29 year olds. Other factors associated with increased mortality included HIV infection, edema, severe malnutrition, pneumonia, tuberculosis, and vomiting. The VL epidemic expanded rapidly over a several-year period, culminating in an epidemic peak in the last third of 2005, spread over two districts, and transformed into a sustained endemic situation by 2007
Wood decay detection in Norway spruce forests based on airborne hyperspectral and ALS data
5openInternationalInternational coauthor/editorWood decay caused by pathogenic fungi in Norway spruce forests causes severe economic losses in the forestry sector, and currently no efficient methods exist to detect infected trees. The detection of wood decay could potentially lead to improvements in forest management and could help in reducing economic losses. In this study, airborne hyperspectral data were used to detect the presence of wood decay in the trees in two forest areas located in Etnedal (dataset I) and Gran (dataset II) municipalities, in southern Norway. The hyperspectral data used consisted of images acquired by two sensors operating in the VNIR and SWIR parts of the spectrum. Corresponding ground reference data were collected in Etnedal using a cut-to-length harvester while in Gran, field measurements were collected manually. Airborne laser scanning (ALS) data were used to detect the individual tree crowns (ITCs) in both sites. Different approaches to deal with pixels inside each ITC were considered: in particular, pixels were either aggregated to a unique value per ITC (i.e., mean, weighted mean, median, centermost pixel) or analyzed in an unaggregated way. Multiple classification methods were explored to predict rot presence: logistic regression, feed forward neural networks, and convolutional neural networks. The results showed that wood decay could be detected, even if with accuracy varying among the two datasets. The best results on the Etnedal dataset were obtained using a convolution neural network with the first five components of a principal component analysis as input (OA = 65.5%), while on the Gran dataset, the best result was obtained using LASSO with logistic regression and data aggregated using the weighted mean (OA = 61.4%). In general, the differences among aggregated and unaggregated data were smallopenDalponte, Michele; Kallio, Alvar J. I.; Ørka, Hans Ole; Næsset, Erik; Gobakken, TerjeDalponte, M.; Kallio, A.J.I.; Ørka, H.O.; Næsset, E.; Gobakken, T
Deep SDSS optical spectroscopy of distant halo stars I. Atmospheric parameters and stellar metallicity distribution
We analyze a sample of tens of thousands of spectra of halo turnoff stars,
obtained with the optical spectrographs of the Sloan Digital Sky Survey (SDSS),
to characterize the stellar halo population "in situ" out to a distance of a
few tens of kpc from the Sun. In this paper we describe the derivation of
atmospheric parameters. We also derive the overall stellar metallicity
distribution based on F-type stars observed as flux calibrators for the
Baryonic Oscillations Spectroscopic Survey (BOSS). Our analysis is based on an
automated method that determines the set of parameters of a model atmosphere
that reproduces each observed spectrum best. We used an optimization algorithm
and evaluate model fluxes by means of interpolation in a precomputed grid. In
our analysis, we account for the spectrograph's varying resolution as a
function of fiber and wavelength. Our results for early SDSS (pre-BOSS upgrade)
data compare well with those from the SEGUE Stellar Parameter Pipeline (SSPP),
except for stars with logg (cgs units) lower than 2.5. An analysis of stars in
the globular cluster M13 reveals a dependence of the inferred metallicity on
surface gravity for stars with logg < 2.5, confirming the systematics
identified in the comparison with the SSPP. We find that our metallicity
estimates are significantly more precise than the SSPP results. We obtain a
halo metallicity distribution that is narrower and more asymmetric than in
previous studies. The lowest gravity stars in our sample, at tens of kpc from
the Sun, indicate a shift of the metallicity distribution to lower abundances,
consistent with what is expected from a dual halo system in the Milky Way.Comment: 10 pages, 5 figures, Table 1 includes model ugriz magnitudes for
stars with different atmospheric parameters in electronic forma
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