79 research outputs found
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
On Type II strings in exact superconformal non-constant RR backgrounds
An explicitly exact superconformal description is provided to some classes of
Type II string theories in non constant RR backgrounds. This is done by
applying the manifest (2,2) approach of Berkovits and Maldacena to Type II
strings and by studying the condition of exact conformal invariance of certain
supersymmetric backgrounds. We find a new set of exact type IIA strings with
non constant RR 2-form and 4-form curvatures and for type IIB with non constant
3-form curvature.Comment: 15 pages; typos and a reference adde
Type IIB superstring action in AdS_5 x S^5 background
We construct the covariant kappa-symmetric superstring action for a type IIB
superstring on AdS_5 x S^5 background. The action is defined as a 2d
sigma-model on the coset superspace SU(2,2|4) / SO(4,1) x SO(5) and is shown to
be the unique one that has the correct bosonic and flat space limits.Comment: 18 pages, latex. v2: Minor corrections, extended comment on conformal
invariance of the 2d theory; v3,v4: Few signs correcte
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
Fermions, T-duality and effective actions for D-branes in bosonic backgrounds
We find the effective action for any D-brane in a general bosonic background
of supergravity. The results are explicit in component fields up to second
order in the fermions and are obtained in a covariant manner. No interaction
terms between fermions and the field , characteristic of the bosonic
actions, are considered. These are reserved for future work. In order to obtain
the actions, we reduce directly from the M2-brane world-volume action to the
D2-brane world-volume action. Then, by means of T-duality, we obtain the other
Dp-brane actions. The resulting Dp-brane actions can be written in a single
compact and elegant expression.Comment: 22 pages, latex, version published by JHEP plus typos corrected in
eq.(44) and eq.(47
Note About Classical Dynamics of Pure Spinor String on AdS_5 x S_5 Background
We will discuss some properties of the pure spinor string on the AdS_5 x S_5
background. Using the classical Hamiltonian analysis we will show that the
vertex operator for the massless state that is in the cohomology of the BRST
charges describes on-shell fluctuations around AdS_5 x S_5 background.Comment: 26. pages, added references, v2:corrected typo
A novel determination of the local dark matter density
We present a novel study on the problem of constructing mass models for the
Milky Way, concentrating on features regarding the dark matter halo component.
We have considered a variegated sample of dynamical observables for the Galaxy,
including several results which have appeared recently, and studied a 7- or
8-dimensional parameter space - defining the Galaxy model - by implementing a
Bayesian approach to the parameter estimation based on a Markov Chain Monte
Carlo method. The main result of this analysis is a novel determination of the
local dark matter halo density which, assuming spherical symmetry and either an
Einasto or an NFW density profile is found to be around 0.39 GeV cm with
a 1- error bar of about 7%; more precisely we find a for the Einasto profile and for the NFW. This is in contrast to the
standard assumption that is about 0.3 GeV cm with an
uncertainty of a factor of 2 to 3. A very precise determination of the local
halo density is very important for interpreting direct dark matter detection
experiments. Indeed the results we produced, together with the recent accurate
determination of the local circular velocity, should be very useful to
considerably narrow astrophysical uncertainties on direct dark matter
detection.Comment: 31 pages,11 figures; minor changes in the text; two figures adde
Conformal Higher Spin Symmetries of 4d Massless Supermultiplets and Invariant Equations in Generalized (Super)Space
Realization of the conformal higher spin symmetry on the 4d massless field
supermultiplets is given. The self-conjugated supermultiplets, including the
linearized SYM theory, are considered in some detail. Duality
between non-unitary field-theoretical representations and the unitary
doubleton--type representations of the 4d conformal algebra is
formulated in terms of a Bogolyubov transform. The set of 4d massless fields of
all spins is shown to form a representation of .
The obtained results are extended to the generalized superspace invariant
under supersymmetries. World line particle interpretation of the
free higher spin theories in the invariant (super)space is
given. Compatible with unitarity free equations of motion in the
invariant (super)space are formulated. A conjecture on the chain of
dualities in the higher spin
gauge theories is proposed.Comment: Latex, 63 pages; no figures.V2 Typos corrected, References updated.
V3.Typos correced, references and an explanation on the relationship with
previous work in section 4 are added. The version to appear in Phys.Rev.
Developing a predictive modelling capacity for a climate change-vulnerable blanket bog habitat: Assessing 1961-1990 baseline relationships
Aim: Understanding the spatial distribution of high priority habitats and
developing predictive models using climate and environmental variables to
replicate these distributions are desirable conservation goals. The aim of this
study was to model and elucidate the contributions of climate and topography to
the distribution of a priority blanket bog habitat in Ireland, and to examine how
this might inform the development of a climate change predictive capacity for
peat-lands in Ireland.
Methods: Ten climatic and two topographic variables were recorded for grid
cells with a spatial resolution of 1010 km, covering 87% of the mainland
land surface of Ireland. Presence-absence data were matched to these variables
and generalised linear models (GLMs) fitted to identify the main climatic and
terrain predictor variables for occurrence of the habitat. Candidate predictor
variables were screened for collinearity, and the accuracy of the final fitted GLM
was evaluated using fourfold cross-validation based on the area under the curve
(AUC) derived from a receiver operating characteristic (ROC) plot. The GLM
predicted habitat occurrence probability maps were mapped against the actual
distributions using GIS techniques.
Results: Despite the apparent parsimony of the initial GLM using only climatic
variables, further testing indicated collinearity among temperature and precipitation
variables for example. Subsequent elimination of the collinear variables and
inclusion of elevation data produced an excellent performance based on the AUC
scores of the final GLM. Mean annual temperature and total mean annual
precipitation in combination with elevation range were the most powerful
explanatory variable group among those explored for the presence of blanket
bog habitat.
Main conclusions: The results confirm that this habitat distribution in general
can be modelled well using the non-collinear climatic and terrain variables tested
at the grid resolution used. Mapping the GLM-predicted distribution to the
observed distribution produced useful results in replicating the projected
occurrence of the habitat distribution over an extensive area. The methods
developed will usefully inform future climate change predictive modelling for
Irelan
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