1,644 research outputs found
DISAGGREGATED ANALYSIS OF SHORT-RUN BEEF SUPPLY RESPONSE
Conceptual problems in model specification of beef supply response studies are investigated and a simultaneous equation model is formulated to estimate annual U.S. carcass supply, demand, and inventories of beef. Three basic issues are addressed: (a) disaggregation, (b) simultaneity, and (c) differentiation between current and expected price effects. Empirical results indicate positive supply response of each quality type of steers and heifers, and negative supply response of cows to current own-price changes. The derived aggregate supply elasticity is positive. The effects of grain price changes on beef price, supply and composition are also evaluated.Demand and Price Analysis, Livestock Production/Industries,
Visualization of Skewed Data: A Tool in R
In this work we present a visualization tool specifically tailored to deal
with skewed data. The technique is based upon the use of two types of notched
boxplots (the usual one, and one which is tuned for the skewness of the data),
the violin plot, the histogram and a nonparametric estimate of the density. The
data is assumed to lie on the same line, so the plots are compatible. We show
that a good deal of information can be extracted from the inspection of this
tool; in particular, we apply the technique to analyze data from synthetic
aperture radar images. We provide the implementation in R.Comment: Submitted to the Revista Colombiana de Estad\'istic
Classification and Verification of Online Handwritten Signatures with Time Causal Information Theory Quantifiers
We present a new approach for online handwritten signature classification and
verification based on descriptors stemming from Information Theory. The
proposal uses the Shannon Entropy, the Statistical Complexity, and the Fisher
Information evaluated over the Bandt and Pompe symbolization of the horizontal
and vertical coordinates of signatures. These six features are easy and fast to
compute, and they are the input to an One-Class Support Vector Machine
classifier. The results produced surpass state-of-the-art techniques that
employ higher-dimensional feature spaces which often require specialized
software and hardware. We assess the consistency of our proposal with respect
to the size of the training sample, and we also use it to classify the
signatures into meaningful groups.Comment: Submitted to PLOS On
Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters II. Berkeley 23, King 1, NGC 559, NGC 6603 and NGC 7245
Context: Open clusters are key to studying the formation and evolution of the
Galactic disc. However, there is a deficiency of radial velocity and chemical
abundance determinations for open clusters in the literature. Aims: We intend
to increase the number of determinations of radial velocities and metallicities
from spectroscopy for open clusters. Methods: We acquired medium-resolution
spectra (R~8000) in the infrared region Ca II triplet lines (~8500 AA) for
several stars in five open clusters with the long-slit IDS spectrograph on the
2.5~m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain).
Radial velocities were obtained by cross-correlation fitting techniques. The
relationships available in the literature between the strength of infrared Ca
II lines and metallicity were also used to derive the metallicity for each
cluster. Results: We obtain = 48.6+/-3.4, -58.4+/-6.8, 26.0+/-4.3 and
-65.3+/-3.2 km s-1 for Berkeley 23, NGC 559, NGC 6603 and NGC 7245,
respectively. We found [Fe/H] =-0.25+/-0.14 and -0.15+/-0.18 for NGC 559 and
NGC 7245, respectively. Berkeley 23 has a low metallicity, [Fe/H]
=-0.42+/-0.13, similar to other open clusters in the outskirts of the Galactic
disc. In contrast, we derived a high metallicity ([Fe/H] =+0.43+/-0.15) for NGC
6603, which places this system among the most metal rich known open clusters.
To our knowledge, this is the first determination of radial velocities and
metallicities from spectroscopy for these clusters, except NGC 6603, for which
radial velocities had been previously determined. We have also analysed ten
stars in the line of sight to King 1. Because of the large dispersion obtained
in both radial velocity and metallicity, we cannot be sure that we have sampled
true cluster members.Comment: 10 pages, 5 figures, accepted for publication in A&A (minor
modifications
Efecto de un incendio forestal sobre la microbiota de un suelo de bosque seco tropical, en el departamento del Tolima
62 p. Recurso Electr?nicoEn Colombia los incendios forestales contribuyen a la degradaci?n de los bosques, uno
de los m?s afectados es el bosque seco tropical (BST). Dado que los microorganismos
son componentes fundamentales del suelo, son empleados como bio-indicadores pues
reflejan los cambios en ?ste. El objetivo del presente trabajo fue evaluar el efecto de un
incendio forestal sobre la microbiota de un suelo de BST en la reserva Santaf? de los
Guaduales. Se evaluaron dos ?reas, una quemada (Q) y una control (C). Se estim? la
actividad (biomasa-C, respiraci?n y actividad enzim?tica), la abundancia (total y de los
grupos funcionales mediante medios selectivos, la abundancia de bacterias tambi?n se
evalu? por qPCR) y la estructura de la comunidad microbiana (bacterias y oxidantes de
amonio con la t?cnica de DGGE); adem?s, se determinaron los par?metros
fisicoqu?micos de: pH, humedad ed?fica, carbono org?nico, nitr?geno total, f?sforo
disponible y amonio La mayor?a de los valores en los par?metros analizados
disminuyeron en el ?rea afectada por el incendio; siendo el nitr?geno (-56%) y el carbono
org?nico (-43%) los que m?s se vieron afectados de los par?metros fisicoqu?micos, y de
los par?metros microbiol?gicos, la estructura de la comunidad bacteriana y la densidad
de los grupos funcionales fueron los m?s sensibles ante la quema. Se concluye que el
incendio afect? de forma negativa el ambiente ed?fico del BST estudiado, adem?s,
teniendo en cuenta la relaci?n observada entre algunos par?metros se sugiere que la
comunidad microbiana tambi?n responde de forma sensible a la cantidad y calidad del
sustrato disponible.
Palabras clave: bioindicadores, par?metros microbiol?gicos, comunidad microbiana,
quema, amonificantes.Forest fires contributed to the degradation of woodlands in Colombia, one of the most
affected is the dry tropical forest. Since microorganisms are fundamental components of
the soil, they are used as biological indicators because they reflect alterations in the soils.
The main goal of this study was to evaluate the effect of a forest fire in the microbiota on
dry tropical forest soils in the Santaf? de los Guaduales reserve. Two areas were
evaluated, one of them was burned (Q) and the other one was used as a control (C). The
activity (biomass-C, respiratory and enzymatic activity), the abundance (total and
functional groups by selective mediums, abundance of bacteria was also assessed by
qPCR) and the microbial community structure (bacteria and ammonium oxidizing bacteria
with the DGGE technique) were determined; besides physicochemical parameters, pH,
soil moisture, organic carbon, total nitrogen, available phosphorus and ammonium were
determined too. Most of the values in the analyzed parameters decreased in the area
affected by fire; being the nitrogen (-56%) and organic carbon (-43%) the most affected
of the physicochemical parameters and of the microbiological parameters, the bacterial
community structure and the functional groups density were the ones that showed greater
sensitivity by burning. We concluded that fires affects in negative way the edaphic
environment of the dry tropical forest studied, moreover, considering the relation found
between some parameters, we suggest that microbial community responds too in a
sensitive way to the quantity and quality of the available substratum.
Keywords: bioindicators, microbiological parameters, microbial communities, burning,
ammonifiers
Situación adidáctica en entornos informáticos sobre sistema de numeración decimal
Esta conferencia recoge alguno de los avances del trabajo de grado que se viene
adelantando como prerrequisito para optar por el tÃtulo de Licenciatura en Educación Básica con
énfasis en Matemáticas de la Universidad de Valle, donde se propone un diseño,
implementación, análisis y evaluación de una secuencia didáctica mediante una serie de
actividades en Geogebra, que conducen a la apropiación, por parte del estudiante, del concepto
de sistema de numeración decimal. De esta manera propiciar al estudiante una situación de
aprendizaje didáctica y darle la oportunidad de construir sus propios conocimientos del
concepto referente al sistema de numeración decimal, mediante el análisis, la exploración, y una
gestión didáctica. Además, que el estudiante pueda mediante la experimentación con las
matemáticas, visualizar conceptos abstractos mediante una constante conexión conceptual con
el nuevo concepto asimilado y los conocimientos previos
The census of interstellar complex organic molecules in the Class I hot corino of SVS13-A
We present the first census of the interstellar Complex Organic Molecules
(iCOMs) in the low-mass Class I protostar SVS13-A, obtained by analysing data
from the IRAM-30m Large Project ASAI (Astrochemical Surveys At IRAM). They
consist of an high-sensitivity unbiased spectral survey at the 1mm, 2mm and 3mm
IRAM bands. We detected five iCOMs: acetaldehyde (CHCHO), methyl formate
(HCOOCH), dimethyl ether (CHOCH), ethanol (CHCHOH) and
formamide (NHCHO). In addition we searched for other iCOMs and ketene
(HCCO), formic acid (HCOOH) and methoxy (CHO), whose only ketene was
detected. The numerous detected lines, from 5 to 37 depending on the species,
cover a large upper level energy range, between 15 and 254 K. This allowed us
to carry out a rotational diagram analysis and derive rotational temperatures
between 35 and 110 K, and column densities between and
cm on the 0."3 size previously determined by
interferometric observations of glycolaldehyde. These new observations clearly
demonstrate the presence of a rich chemistry in the hot corino towards SVS13-A.
The measured iCOMs abundances were compared to other Class 0 and I hot corinos,
as well as comets, previously published in the literature. We find evidence
that (i) SVS13-A is as chemically rich as younger Class 0 protostars, and (ii)
the iCOMs relative abundances do not substantially evolve during the
protostellar phase.Comment: 24 pages, MNRAS in pres
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