837 research outputs found
Ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfishScarus zelindae
Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals. Thus, terminal phase individuals forage with lower feeding rates compared to juveniles and initial phase individuals. The highest relative foraging frequency of S. zelindae was on epilithic algae matrix (EAM) with similar values for juveniles (86.6%), initial phase (88.1%) and terminal phase (88.6%) individuals. The second preferred benthos for juveniles was sponge (11.6%) compared with initial (4.5%) and terminal life phases (1.3%). Different life phases of S. zelindae foraged on different benthos according to their availability. Based on Ivlev's electivity index, juveniles selected EAM and sponge, while initial phase and terminal phase individuals only selected EAM. Our findings demonstrate that the foraging frequency of the endemic parrotfish S. zelindae is reduced according to body size and that there is a slight ontogenetic change in feeding selectivity. Therefore, ecological knowledge of ontogenetic variations on resource use is critical for the remaining parrotfish populations which have been dramatically reduced in the Southwestern Atlantic Ocean
Magneto-optical trap for metastable helium at 389 nm
We have constructed a magneto-optical trap (MOT) for metastable triplet
helium atoms utilizing the 2 3S1 -> 3 3P2 line at 389 nm as the trapping and
cooling transition. The far-red-detuned MOT (detuning Delta = -41 MHz)
typically contains few times 10^7 atoms at a relatively high (~10^9 cm^-3)
density, which is a consequence of the large momentum transfer per photon at
389 nm and a small two-body loss rate coefficient (2 * 10^-10 cm^3/s < beta <
1.0 * 10^-9 cm^3/s). The two-body loss rate is more than five times smaller
than in a MOT on the commonly used 2 3S1 -> 2 3P2 line at 1083 nm. Furthermore,
we measure a temperature of 0.46(1) mK, a factor 2.5 lower as compared to the
1083 nm case. Decreasing the detuning to Delta= -9 MHz results in a cloud
temperature as low as 0.25(1) mK, at small number of trapped atoms. The 389 nm
MOT exhibits small losses due to two-photon ionization, which have been
investigated as well.Comment: 11 page
DEGRADABILIDADE in vitro DA PROTEĂNA DE ESPĂCIES ARBĂREAS DO SEMI-ĂRIDO BRASILEIRO
This experiment was carried out to
evaluate the protein degradability in vitro of arboreal
plants from Brazilian semi-arid. The plants tested were
angico (Anadenanthera colubrina), algaroba (Prosopis
juliflora), espinheiro (Acacia glomerosa), juazeiro
(Ziziphus joazeiro) and soybean meal, which had crude
protein values of 22,5 16,0, 22,0, 19,0 and 38,0%,
respectively. Samples (60 mg) were incubated with
McDougal (8 ml) and inoculated ruminal fluid (2 ml).
Aliquots (1 ml) were taking after 0, 6, 12, 24, 36 and 48
hours for analysis of ammonia, soluble protein and
microbial protein. Soybean meal and the algaroba
showed larger ammonia production and concentration
of soluble protein compared to the other treatments.
Soybean meal also displayed higher values for microbial
protein. The treatment with angico was the one that
displayed closed values towards soybean in regard to
microbial protein, in spite of showing lesser ammonia
production. The largest value of potential degradability
66,47%, was observed for the treatment with soybean
meal, followed by the algaroba 46,27% and of the angico
45,20. Very low degradability was observed for the
espinheiro and juazeiro, 19,16 e16,63%, respectively.
Among the studied plants the angico and the algaroba
were better sources of protein.O experimento teve como objetivo avaliar
a degradabilidade in vitro da proteĂna de plantas
arbĂłreas do semi-ĂĄrido brasileiro e do farelo de soja.
As plantas utilizadas foram angico (Anadenanthera
colubrina), algaroba (Prosopis juliflora), espinheiro
(Acacia glomerosa), juazeiro (Ziziphus joazeiro) e o
farelo de soja, com valores de proteĂna bruta de 22,5
16,0, 22,0, 19,0 e 38,0%, respectivamente. Amostras
de cada planta (60 mg) foram incubadas em 8 ml de
meio tampão de McDougal, com adição de 2 ml de
inĂłculo ruminal. Nos tempos 0, 6, 12, 24, 36 e 48 horas
apĂłs a incubação foi retirada uma alĂquota de 1,0 ml
para anĂĄlise de amĂ´nia, proteĂna solĂşvel e proteĂna
microbiana. O farelo de soja e a algaroba
proporcionaram maiores produção de amônia e
concentração de proteĂna solĂşvel em relação aos outros
alimentos, sendo que o farelo de soja apresentou maior
valor de proteĂna microbiana. O tratamento com o
angico foi o que mais se aproximou à soja com relação
ao valor de proteĂna microbiana, apesar da sua menor
produção de amônia. O maior valor de degradabilidade
potencial 66,47 %, foi observado no tratamento com
farelo de soja, seguidos dos tratamentos da algaroba
46,27% e angico 45,20%. Foram observados valores
de degradabilidade muito baixos para o espinheiro e
juazeiro, 19,16 e 16,63%, respectivamente. O angico e
a algaroba apresentaram-se como melhores fontes de
proteĂna entre as plantas avaliadas
A self-consistent determination of the temperature profile and the magnetic field geometry in winds of late-type stars
Cool giant and supergiant stars generally present low velocity winds with
high mass loss rates. Several models have been proposed to explain the
acceleration process of these winds. Although dust is known to be present in
these objects, the radiation pressure on these particles is uneffective in
reproducing the observed physical parameters of the wind. The most promising
acceleration mechanism cited in the literature is the transference of momentum
and energy from Alfven waves to the gas. Usually, these models consider the
wind to be isothermal. We present a stellar wind model in which the Alfven
waves are used as the main acceleration mechanism, and determine the
temperature profile by solving the energy equation taking into account both the
radiative losses and the wave heating. We also determine self-consistently the
magnetic field geometry as the result of the competition between the magnetic
field and the thermal pressures gradient. As main result, we show that the
magnetic geometry present a super-radial index in the region where the gas
pressure is increasing. However, this super-radial index is greater than that
observed for the solar corona.Comment: Accepted for publication in Space Science Reviews. Presented at the
World Space Environment Forum 2005, Austria. 8 pages, 2 figure
Kaluza-Klein Cosmology With Modified Holographic Dark Energy
We investigate the compact Kaluza-Klein cosmology in which modified
holographic dark energy is interacting with dark matter. Using this scenario,
we evaluate equation of state parameter as well as equation of evolution of the
modified holographic dark energy. Further, it is shown that the generalized
second law of thermodynamics holds without any constraint.Comment: 13 pages, accepted for publication in Gen. Relativ. Gravi
Neurocitoma central: relato de dois casos
Neurocitoma central ĂŠ um tumor neuroectodĂŠrmico raro, geralmente localizado nos ventrĂculos laterais. Uma mulher de 26 anos e um homem de 33 anos apresentaram-se com hipertensĂŁo intracraniana. Exames de imagem revelaram tumor intraventricular heterogĂŞneo, que impregnava por contraste, ocupando os ventrĂculos laterais e causando hidrocefalia. A mulher faleceu no pĂłs-operatĂłrio e o homem estĂĄ livre de recidiva apĂłs trĂŞs anos. Ambos os tumores eram sĂłlidos, com cĂŠlulas arredondadas, lembrando oligodendroglia, positivas para sinaptofisina, cromogranina e NSE e algumas para GFAP, vimentina e proteĂna S-100. Microscopia eletrĂ´nica mostrou neurĂłpilo entre os corpos celulares, mas sinapses eram raras63410841089Central neurocytomas are rare neuroectodermal tumors believed to arise from the subependymal matrix of the lateral ventricles. Case reports: A 26-year-old woman and a 33-year-old man each had a large, heterogeneous, contrast enhancing mass in the lateral ventricles at the foramen of Monro causing bilateral hydrocephalus. The woman died after surgery, but the man is asymptomatic after three years. Histopathology: Both tumors were composed of isomorphic rounded cells positive for synaptophysin, chromogranin and NSE, while some reacted for GFAP, vimentin and S-100 protein. Electron microscopy revealed neuropil-like tissue between cells, but synapses were rar
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
The Lambda(b) differential production cross section and the cross section
ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum
pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7
TeV using data collected by the CMS experiment at the LHC. The measurements are
based on Lambda(b) decays reconstructed in the exclusive final state J/Psi
Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and
Lambda to proton pion, using a data sample corresponding to an integrated
luminosity of 1.9 inverse femtobarns. The product of the cross section times
the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls
faster than that of b mesons. The measured value of the cross section times the
branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06
+/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for
anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are
statistical and systematic, respectively.Comment: Submitted to Physics Letters
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