1,148 research outputs found
A generalized definition of dosimetric quantities
The current definitions of microdosimetric and dosimetric quantities use the notion of 'ionizing radiation'. However, this notion is not rigorously defined, and its definition would require the somewhat arbitrary choice of specified energy cut-off values for different types of particles. Instead of choosing fixed cut-off values one can extend the system of definitions by admitting the free selection of a category of types and energies of particles that are taken to be part of the field. In this way one extends the system of dosimetric quantities. Kerma and absorbed dose appear then as special cases of a more general dosimetric quantity, and an analogue to kerma can be obtained for charged particle fields; it is termed cema. A modification that is suitable for electron fields is termed reduced cema
Do DSGE models forecast more accurately out-of sample than VAR models?
Recently, it has been suggested that macroeconomic forecasts from estimated dynamic stochastic general equilibrium (DSGE) models tend to be more accurate out-of-sample than random walk forecasts or Bayesian vector autoregression (VAR) forecasts. Del Negro and Schorfheide (2013) in particular suggest that the DSGE model forecast should become the benchmark for forecasting horse-races. We compare the real-time forecasting accuracy of the Smets and Wouters (2007) DSGE model with that of several reduced-form time series models. We first demonstrate that none of the forecasting models is efficient. Our second finding is that there is no single best forecasting method. For example, typically simple AR models are most accurate at short horizons and DSGE models are most accurate at long horizons when forecasting output growth, while for inflation forecasts the results are reversed. Moreover, the relative accuracy of all models tends to evolve over time. Third, we show that there is no support to the common practice of using large-scale Bayesian VAR models as the forecast benchmark when evaluating DSGE models. Indeed, low-dimensional unrestricted AR and VAR forecasts may forecast more accurately. Copyright © 2013 by Emerald Group Publishing Limited
A software to estimate heat stress impact on dairy cattle productive performance
ArticleThe aim of this study is to develop a computational tool, based on the Temperature and
Humidity Index value, to characterize the thermal environment in dairy cattle barns and to
evaluate the impact of thermal stress on productive performance. The software for the thermal
environment prediction, and determination of the influence of heat stress on dairy cow
productivity (Ambi + Leite) was developed using the C# programming language in the Microsoft
Visual C# 2010 Express Integrated Development Environment. The following scenario was
considered for the program test: air temperature 32°C, relative air humidity 70% and milk
production potential in thermoneutrality condition 20 kg cow-1 day-1
. The prediction of the
thermal environment based on the simulated situations indicates that the animals are submitted to
a moderate heat stress condition with THI equal to 82.81. In this condition a decrease of
approximately 26% in milk production and a reduction of 4 kg cow-1 day-1
in food intake was
calculated. In conclusion, the developed software can be a practical tool to assist the producer in
making-decision processes
PENGARUH PENGOLAHAN DAN PENYIMPANAN TERHADAP STABILITAS ASAM LEMAK OMEGA-3 PADA TELUR DAN IKAN
Effect of Processing and Storage on the Stability of Omega-3 Fatty Acids in Egg and Fish.Long chain omega-3 fatty acids such as Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA), were very important for brain development, immunity, retina and growth of child. One of natural source of these fatty acids is fish which has been processed into variety food such as abon. The other source is modifying hen egg which potentially to be added into many kind of food after processed as egg flour. This research examine the effect of processing and storage of abon and eggs flour. The methode of this research was one-group pre post test (minimal control) and the data was prepared in tabulation. Processing in to aboon ikan make EPA lost for 10.63% and DHA 7.63%. This product was acceptable, but the stability of the fatty acids were low, EPA lost 43.8% and DHA lost by 52.4% for 4 months. The eggs prepared by our lab contained 2.5% omega-3 fatty acid. To make egg yolk flour was used Spray Drying process. This process make EPA lost 43.94% and DHA 6.20%. After storing for 4 months, egg yolk flour was very stable. Because of these reason, these products can be used to supplement fatty acids in daily diet. Eggs flour can be used in any food product to supply omega-3 fatty acid for the risk group.Keywords: omega-3 fatty acid, food processing, food storage, egg flou
Effect of environmental temperature during the of brooding period on growing period of pullets viscera and tibia
ArticlePoultry production in subtropical and tropical regions faces many problems, one of
which is the high air temperature causing thermal stress, particularly dangerous in high-producing
birds. Thus, the negative effects caused by heat stress (HS) must be managed. The objective of
this study was to evaluate the effects of four different levels of HS in viscera and tibia of pullets.
A total of 648 chicks (Lohmann LSL Lite) were used in this study in two different phases. The
pre-experimental phase (PEP) was from day 1 through 6 weeks of age. The birds were reared
with three different environmental temperatures: thermal comfort, hot and cold. The experimental
phase (EP) was conducted from the 7th to the 17th week. Pullets from each thermal environment
of the PEP were submitted to: 20 °C, 25 °C, 30 °C, 35 °C. At the end of the 17th week of age 120
pullets were euthanatized and the organs, heart, liver, spleen and gizzard were weighed, as also
their tibias. Effects of PEP, and its interaction with EP, were not significant (P < 0.05) for viscera
and tibia weight. However, a significant increase (P < 0.05) in heart weight with the decrease of
the environmental temperature was observed, being the pullets subject to 20ºC and 25 °C with
the heaviest weights. For the liver, pullets subject to the 35 °C had the lowest weight and were
different (P < 0.05) from the other three treatments. For gizzard, the difference (P < 0.05) was
between the treatments 20ºC and 35 °C. These results indicate that brooding temperatures tested
during the first 6 weeks of life did not affect the viscera and bone weight during the growing
phase
KUALITAS BEBERAPA TELUR BERMEREK KHUSUS DIBANDINGKAN DENGAN TELUR AYAM RAS DAN BURAS
Quality of Branded Eggs as Compared to Layer and Domestic Chicken Eggs.Many branded eggs found in the market claimed as low in cholesterol (Low Cholesterol Egg, Golden Egg), or claimed as high in omega-3 fatty acid content (Omega-3 Egg), besides common domestic and layer chicken eggs. This brand trend attracted the consumer to buy. Nonetheless, there is a need to evaluate further on the quality they claimed besides the physical quality. The evaluation was done regarded of those 5 types of eggs on their outer measurements (shape abnormalities, size indexes, shell thickness); and inner measurements (Haugh Units, yolk color score). The results indicated that all egg types had normal appearance with size indexes of 1.24-1.38. The Haugh Units was arround 28.7-67.3 and yolk color score was arround 5.0-13.3. Based on those results, the zerro week marketed eggs (Group I) clasified as A quality and the one week marketed eggs (Group II) were B quality. The data on chemical analyses indicated that the omega-3 fatty acid content was significantly the highest (p<0.05) in Omega-3 egg, while the cholesterol content was 'similar in all types of eggs. The easiest way to judge the quality are from the shape and size of the eggs. Those have to be in normal shape and uniform size. While the claimed on low cholesterol content is not proven.Keywords: cholesterol content, omega-3 content, physical quality, chicken eggs
Probing Non-Standard Couplings of Neutrinos at the Borexino Detector
The present experimental status does not exclude weak-strength non-standard
interactions of neutrinos with electrons. These interactions can be revealed in
solar neutrino experiments. Our discussion covers several aspects related to
this issue. First, we perform an analysis of the Super Kamiokande and SNO data
to investigate their sensitivity to such interactions. In particular, we show
that the \nu_e oscillation into sterile neutrinos can be still allowed if \nu_e
has extra interactions of the proper strength. Second, we suggest that the
Borexino detector can provide good signatures for these non-standard
interactions. Indeed, in Borexino the shape of the recoil electron spectrum
from the \nu e \to \nu e scattering essentially does not depend on the solar
neutrino conversion details, since most of the signal comes from the
mono-energetic ^7Be neutrinos. Hence, the partial conversion of solar \nu_e
into a a nearly equal mixture of \nu_\mu and \nu_\tau, as is indicated by the
atmospheric neutrino data, offers the chance to test extra interactions of
\nu_\tau, or of \nu_e itself.Comment: 17 LaTeX pages, 15 postscript figures, uses epsfig.sty. More extended
discussion about the spectral deformation for both Super-Kamiokande and
Borexino; new figures are adde
Computational fluids dynamics (CFD) in the spatial distribution of air velocity in prototype designed for animal experimentation in controlled environments
ArticleMaintaining a comfortable and productive thermal environment is one of the major
challenges of poultry farming in tropical and hot climates. The thermal environment encompasses
a number of factors that interact with each other and reflect the actual thermal sensation of the
animals. These factors characterize the microclimate inside the facilities and influence the
behaviour, performance and well-being of the birds. Thus, the objective of this study is to propose
and validate a computational model of fluid dynamics to evaluate the spatial distribution of air
velocity and the performance of a system designed to control air velocity variation for use in
experiments with birds in controlled environment. The performance of the experimental
ventilation prototype was evaluated based on air velocity distribution profiles in cages. Each
prototype consisted of two fans coupled to a PVC pipe 25 cm in diameter, one at each end of the
pipe, with airflow directed along the entire feeder installed in front of the cages. The contour
conditions considered for the simulation of airflow inside the cage were air temperature of 35 °C
at the entrance and exit of the cage; air velocity equal to 2.3 m s
-1
at the entrance of the cage;
pressure of 0 Pa. The model proposed in this study was representative when compared to the
experimental measurements, and it can be used in the study of air flow behaviour and distribution
for the improvement of the prototype design for later studies
Influence of shower fluctuations and primary composition on studies of the shower longitudinal development
We study the influence of shower fluctuations, and the possible presence of
different nuclear species in the primary cosmic ray spectrum, on the
experimental determination of both shower energy and the proton air inelastic
cross section from studies of the longitudinal development of atmospheric
showers in fluorescence experiments. We investigate the potential of track
length integral and shower size at maximum as estimators of shower energy. We
find that at very high energy (~10^19-10^20 eV) the error of the total energy
assignment is dominated by the dependence on the hadronic interaction model,
and is of the order of 5%. At lower energy (~10^17-10^18 eV), the uncertainty
of the energy determination due to the limited knowledge of the primary cosmic
ray composition is more important. The distribution of depth of shower maximum
is discussed as a measure of the proton-air cross section. Uncertainties in a
possible experimental measurement of this cross section introduced by intrinsic
shower fluctuations, the model of hadronic interactions, and the unknown
mixture of primary nuclei in the cosmic radiation are numerically evaluated.Comment: 12 pages, 11 figures, 4 table
Kosterlitz Thouless Universality in Dimer Models
Using the monomer-dimer representation of strongly coupled U(N) lattice gauge
theories with staggered fermions, we study finite temperature chiral phase
transitions in (2+1) dimensions. A new cluster algorithm allows us to compute
monomer-monomer and dimer-dimer correlations at zero monomer density (chiral
limit) accurately on large lattices. This makes it possible to show
convincingly, for the first time, that these models undergo a finite
temperature phase transition which belongs to the Kosterlitz-Thouless
universality class. We find that this universality class is unaffected even in
the large N limit. This shows that the mean field analysis often used in this
limit breaks down in the critical region.Comment: 4 pages, 4 figure
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