132 research outputs found
Seismic constraints on rotation of Sun-like star and mass of exoplanet
Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like
stars. Stellar dynamos, however, are poorly understood owing to the scarcity of
observations of rotation and magnetic fields in stars. Here, inferences are
drawn on the internal rotation of a distant Sun-like star by studying its
global modes of oscillation. We report asteroseismic constraints imposed on the
rotation rate and the inclination of the spin axis of the Sun-like star HD
52265, a principal target observed by the CoRoT satellite that is known to host
a planetary companion. These seismic inferences are remarkably consistent with
an independent spectroscopic observation (rotational line broadening) and with
the observed rotation period of star spots. Furthermore, asteroseismology
constrains the mass of exoplanet HD 52265b. Under the standard assumption that
the stellar spin axis and the axis of the planetary orbit coincide, the minimum
spectroscopic mass of the planet can be converted into a true mass of 1.85
(+0.52,-0.42) M_Jupiter, which implies that it is a planet, not a brown dwarf.Comment: Published in Proceedings of the National Academy of Sciences (5
pages, 5 figures, 3 tables). Available at
http://www.pnas.org/cgi/doi/10.1073/pnas.130329111
Tethered Spinal Cord with Double Spinal Lipomas
Although lumbosacral lipoma is reported to occur in 4-8 of 100,000 patients, and 66% of lipomyelomeningoceles in young patients are accompanied by hypertrophic filum terminale, it is very rare to find two isolated spinal lipomas simultaneously. A 3 month-old baby girl was admitted to the hospital for a protruding, non-tender, soft, subcutaneous 2.5 cm mass of the lumbosacral area that had been present since birth. Simple radiography showed a spinal posterior arch defect from L3 to L5, and magnetic resonance imaging (MRI) demonstrated two isolated spinal lipomas, a transitional type from L3 to L5, and a terminal type below S1 without dural defect. The cornus medullaris was severely tethered descending to the S1, but there was no cerebellar or brain stem herniation on the MRI. We suggest that the presence of a combined spinal lipoma should be a point for careful differentiation in an infant with spinal lipoma
Experimental study of the atmospheric neutrino backgrounds for proton decay to positron and neutral pion searches in water Cherenkov detectors
The atmospheric neutrino background for proton decay to positron and neutral
pion in ring imaging water Cherenkov detectors is studied with an artificial
accelerator neutrino beam for the first time. In total, about 314,000 neutrino
events corresponding to about 10 megaton-years of atmospheric neutrino
interactions were collected by a 1,000 ton water Cherenkov detector (KT). The
KT charged-current single neutral pion production data are well reproduced by
simulation programs of neutrino and secondary hadronic interactions used in the
Super-Kamiokande (SK) proton decay search. The obtained proton to positron and
neutral pion background rate by the KT data for SK from the atmospheric
neutrinos whose energies are below 3 GeV is about two per megaton-year. This
result is also relevant to possible future, megaton-scale water Cherenkov
detectors.Comment: 13 pages, 16 figure
Measurement of single charged pion production in the charged-current interactions of neutrinos in a 1.3 GeV wide band beam
Single charged pion production in charged-current muon neutrino interactions
with carbon is studied using data collected in the K2K long-baseline neutrino
experiment. The mean energy of the incident muon neutrinos is 1.3 GeV. The data
used in this analysis are mainly from a fully active scintillator detector,
SciBar. The cross section for single production in the resonance
region ( GeV/) relative to the charged-current quasi-elastic cross
section is found to be 0.734 . The energy-dependent cross
section ratio is also measured. The results are consistent with a previous
experiment and the prediction of our model.Comment: 15 pages, 12 figures, 7 tables. Uses revtex4. Minor revisions to
match version accepted for publication in Physical Review
Clinical heterogeneity of neuro-inflammatory PET profiles in early Alzheimer’s disease
The relationship between neuroinflammation and cognition remains uncertain in early Alzheimer’s disease (AD). We performed a cross-sectional study to assess how neuroinflammation is related to cognition using TSPO PET imaging and a multi-domain neuropsychological assessment. A standard uptake value ratio (SUVR) analysis was performed to measure [18F]-DPA-714 binding using the cerebellar cortex or the whole brain as a (pseudo)reference region. Among 29 patients with early AD, the pattern of neuroinflammation was heterogeneous and exhibited no correlation with cognition at voxel-wise, regional or whole-brain level. The distribution of the SUVR values was independent of sex, APOE phenotype, early and late onset of symptoms and the presence of cerebral amyloid angiopathy. However, we were able to demonstrate a complex dissociation as some patients with similar PET pattern had opposed neuropsychological profiles while other patients with opposite PET profiles had similar neuropsychological presentation. Further studies are needed to explore how this heterogeneity impacts disease progression
Eco-bio-social determinants for house infestation by non-domiciliated Triatoma dimidiata in the Yucatan peninsula, Mexico
Background
Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control.
Methodology/principal findings
We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation.
Conclusions/significance
These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control
Phylogeography and Genetic Variation of Triatoma dimidiata, the Main Chagas Disease Vector in Central America, and Its Position within the Genus Triatoma
Chagas disease is a serious parasitic disease of Latin America. Human contamination in poor rural or periurban areas is mainly attributed to haematophagous triatomine insects. Triatoma includes important vector species, as T. dimidiata in Central and Meso-America. DNA sequences, phylogenetic methods and genetic variation analyses are combined in a large interpopulational approach to investigate T. dimidiata and its closest relatives within Triatoma. The phylogeography of Triatoma indicates two colonization lineages northward and southward of the Panama isthmus during ancient periods, with T. dimidiata presenting a large genetic variability related to evolutionary divergences from a Mexican-Guatemalan origin. One clade remained confined to Yucatan, Chiapas, Guatemala and Honduras, with extant descendants deserving species status: T. sp. aff. dimidiata. The second clade gave rise to four subspecies: T. d. dimidiata in Guatemala and Mexico (Chiapas) up to Honduras, Nicaragua, Providencia island, and introduced into Ecuador; T. d. capitata in Panama and Colombia; T. d. maculipennis in Mexico and Guatemala; and T. d. hegneri in Cozumel island. This taxa distinction may facilitate the understanding of the diversity of vectors formerly included under T. dimidiata, their different transmission capacities and the disease epidemiology. Triatoma dimidiata will offer more problems for control than T. infestans in Uruguay, Chile and Brazil, although populations in Ecuador are appropriate targets for insecticide-spraying
Measurement of inclusive production in the Charged-Current Interactions of Neutrinos in a 1.3-GeV wide band beam
In this paper we report on the measurement of the rate of inclusive
production induced by charged-current neutrino interactions in a CH
target at a mean energy of 1.3 GeV in the K2K near detector. Out of a sample of
11,606 charged current neutrino interactions, we select 479 events with
two reconstructed photons. We find that the cross section for the inclusive
production relative to the charged-current quasi-elastic cross section
is
The energy dependent cross section ratio is also measured. The results are
consistent with previous experiments for exclusive channels on different
targets.Comment: 18 pages, 11 figures, submitted to PR
Improved search for oscillation in a long-baseline accelerator experiment
We performed an improved search for oscillation with the
KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the
full data sample of \xspace protons on target. No evidence
for a appearance signal was found, and we set bounds on the oscillation parameters. At = , the best fit value of the K2K disappearance analysis,
we set an upper limit of 0.13 at 90% confidence
level.Comment: 5 pages, 2 figure
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