50,947 research outputs found
Detection of Exotic Massive Hadrons in Ultra High Energy Cosmic Ray Telescopes
We investigate the detection of exotic massive strongly interacting hadrons
(uhecrons) in ultra high energy cosmic ray telescopes. The conclusion is that
experiments such as the Pierre Auger Observatory have the potential to detect
these particles. It is shown that uhecron showers have clear distinctive
features when compared to proton and nuclear showers. The simulation of uhecron
air showers, and its detection and reconstruction by fluorescence telescopes is
described. We determine basic cuts in observables that will separate uhecrons
from the cosmic ray bulk, assuming this is composed by protons. If these are
composed by heavier nucleus the separation will be much improved. We also
discuss photon induced showers. The complementarity between uhecron detection
in accelerator experiments is discussed.Comment: 9 page 9 figure
Charge orders, magnetism and pairings in the cuprate superconductors
We review the recent developments in the field of cuprate superconductors
with the special focus on the recently observed charge order in the underdoped
compounds. We introduce new theoretical developments following the study of the
antiferromagnetic (AF) quantum critical point (QCP) in two dimensions, in which
preemptive orders in the charge and superconducting (SC) sectors emerged, that
are in turn related by an SU(2) symmetry. We consider the implications of this
proliferation of orders in the underdoped region, and provide a study of the
type of fluctuations which characterize the SU(2) symmetry. We identify an
intermediate energy scale where the SU(2) pairing fluctuations are dominant and
argue that they are unstable towards the formation of a Resonant Peierls
Excitonic (RPE) state at the pseudogap (PG) temperature . We discuss the
implications of this scenario for a few key experiments.Comment: 16 pages, 17 figure
An evolutionary perspective on the kinome of malaria parasites
Malaria parasites belong to an ancient lineage that diverged very early from the main branch of eukaryotes. The approximately 90-member plasmodial kinome includes a majority of eukaryotic protein kinases that clearly cluster within the AGC, CMGC, TKL, CaMK and CK1 groups found in yeast, plants and mammals, testifying to the ancient ancestry of these families. However, several hundred millions years of independent evolution, and the specific pressures brought about by first a photosynthetic and then a parasitic lifestyle, led to the emergence of unique features in the plasmodial kinome. These include taxon-restricted kinase families, and unique peculiarities of individual enzymes even when they have homologues in other eukaryotes. Here, we merge essential aspects of all three malaria-related communications that were presented at the Evolution of Protein Phosphorylation meeting, and propose an integrated discussion of the specific features of the parasite's kinome and phosphoproteome
Photometric Properties of 47 Clusters of Galaxies: I. The Butcher-Oemler Effect
We present gri CCD photometry of 44 Abell clusters and 4 cluster candidates.
Twenty one clusters in our sample have spectroscopic redshifts. Fitting a
relation between mean g, r and i magnitudes, and redshift for this subsample,
we have calculated photometric redshifts for the remainder with an estimated
accuracy of 0.03. The resulting redshift range for the sample is 0.03<z<0.38.
Color-magnitude diagrams are presented for the complete sample and used to
study evolution of the galaxy population in the cluster environment. Our
observations show a strong Butcher-Oemler effect (Butcher & Oemler 1978, 1984),
with an increase in the fraction of blue galaxies (f_B) with redshift that
seems more consistent with the steeper relation estimated by Rakos and
Schombert (1995) than with the original one by Butcher & Oemler (1984).
However, in the redshift range between ~ 0.08 and 0.2, where most of our
clusters lie, there is a wide range of f_B values, consistent with no redshift
evolution of the cluster galaxy population. A large range of f_B values is also
seen between ~ 0.2 and 0.3, when Smail at al. (1998) x-ray clusters are added
to our sample. The discrepancies between samples underscore the need for an
unbiased sample to understand how much of the Butcher-Oemler effect is due to
evolution, and how much to selection effects. We also tested the idea proposed
by Garilli et al. (1996) that there is a population of unusually red galaxies
which could be associated either with the field or clusters, but we find that
these objects are all near the limiting magnitude of the images (20.5<r<22) and
have colors that are consistent with those expected for stars or field galaxies
at z ~ 0.7.Comment: 35 pages including 8 figures, submitted to A
Teratoma Sacrococcígeo:Caso Clínico
O teratoma sacrococcígeo, embora
raro, é a neoplasia mais frequentemente
diagnosticada no período
neonatal. O diagnóstico é geralmente
estabelecido após o nascimento, apesar
do uso da ultrassonografia obstétrica
permitir um número crescente de
sinalizações pré -natais. O principal
diagnóstico diferencial é o mielomeningocelo.
A monitorização de marcadores
tumorais sugestivos da presença de
células malignas de um tumor do saco
vitelino associado, tal como a alfa-
-fetoproteína, e a ressecção precoce
do tumor são recomendáveis.
Apresenta -se o caso clínico de
um recém -nascido do sexo feminino a
quem foi detectado ao nascimento uma
massa sacrococcígea. A ressonância
magnética nuclear admitiu tratar -se de
um teratoma sacrococcígeo e o valor
de alfa -fetoproteína era normal para
a idade da doente. Foi realizada ressecção
total do tumor com remoção do
cóccix e confi rmado o diagnóstico em
estudo anátomo -patológico. A reavaliação
posterior da criança revelou um
valor decrescente da alfa -fetoproteína,
ausência de défi ces motores e um bom
aspecto cosmético.
A apresentação deste caso clínico
pretende realçar a importância do diagnóstico
precoce, fundamental para a
abordagem terapêutica adequada e melhor
prognóstico
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