2,160 research outputs found
H^+_2$ in a strong magnetic field described via a solvable model
We consider the hydrogen molecular ion in the presence of a strong
homogeneous magnetic field. In this regime, the effective Hamiltonian is almost
one dimensional with a potential energy which looks like a sum of two Dirac
delta functions. This model is solvable, but not close enough to our exact
Hamiltonian for relevant strenght of the magnnetic field. However we show that
the correct values of the equilibrium distance as well as the binding energy of
the ground state of the ion, can be obtained when incorporating perturbative
corrections up to second order. Finally, we show that exists for
sufficiently large magnetic fields
Phylogenetic classification and clinical aspects of a new putative Deltapapillomavirus associated with skin lesions in cattle
Bovine papillomaviruses (BPVs) are recognized as causal agents of benign and malignant tumors in cattle. Thirteen types of BPVs have already been described and classified into 3 distinct genera. Divergences in the nucleotide sequence of the L1 gene are used to identify new viral types through the employment of PCR assays with degenerated primers. in the present study, a method for identifying BPVs based on PCR-RFLP and DNA sequencing allowed the identification of a new putative Deltapapillomavirus, designated JN/3SP (JQ280500.1). the analysis of the L1 gene showed that this strain was most closely related to the BPVs -1, -2, -13, and OaPV1 (71-73% genetic similarity). in this study, we describe the detection of this new putative Deltapapillomavirus type and verify its phylogenetic position within the genus.Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de NĂvel Superior (CAPES)Inst Butantan, Lab Genet, SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Programa Posgrad Biol Estrutural & Func, SĂŁo Paulo, BrazilUniv SĂŁo Paulo, Programa Posgrad Interunidades Biotecnol, SĂŁo Paulo, BrazilUniv Fed Pernambuco, Dept Bot, Recife, PE, BrazilUniv Fed Integracao Latino Amer, Dept Biol, Foz Do Iguacu, PR, BrazilUniversidade Federal de SĂŁo Paulo, Programa Posgrad Biol Estrutural & Func, SĂŁo Paulo, BrazilCNPq: 402539/2011-7CNPq: 554816/2006-7Web of Scienc
Genetic comparison of sickle cell anaemia cohorts from Brazil and the United States reveals high levels of divergence
Genetic analysis of admixed populations raises special concerns with regard to study design and data processing, particularly to avoid population stratification biases. The point mutation responsible for sickle cell anaemia codes for a variant hemoglobin, sickle hemoglobin or HbS, whose presence drives the pathophysiology of disease. Here we propose to explore ancestry and population structure in a genome-wide study with particular emphasis on chromosome 11 in two SCA admixed cohorts obtained from urban populations of Brazil (Pernambuco and Sao Paulo) and the United States (Pennsylvania). Ancestry inference showed different proportions of European, African and American backgrounds in the composition of our samples. Brazilians were more admixed, had a lower African background (43% vs. 78% on the genomic level and 44% vs. 76% on chromosome 11) and presented a signature of positive selection and Iberian introgression in the HbS region, driving a high differentiation of this locus between the two cohorts. The genetic structures of the SCA cohorts from Brazil and US differ considerably on the genome-wide, chromosome 11 and HbS mutation locus levels9CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESP8367/2011-1; 150398/2013-1; 304455/2012-1; 310938/2014-7; 305218/2017-48367/2011-1; 150398/2013-1; 304455/2012-1; 310938/2014-7; 305218/2017-42008/57441-0; 2014/00984-3; 2012/06438-5; 2015/13152-9; 2008/10596-
Monilethrix: the use of tricoscopy in clinical diagnosis
Monilethrix is a Greco-Latin term that mean âhair stickâ1. It is a rare genetic disorder with autosomal dominant inheritance, characterized by degeneration of the hair matrix and formation of defective cuticle. The hairs are brittle and not exceed a few inches length. The scalp is the most affected region and the most common clinical presentation is alopecia associated with keratosis follicularis2,3. The diagnosis is clinical and the tricoscopia evidence moniliformes changes (switching between wide and narrow band)Monilethrix Ă© termo de origem greco-latina que significa âcabelo em colarâ1. Trata-se de doença genĂ©tica rara, com herança autossĂŽmica dominante, caracterizada por degeneração da matriz do cabelo e forma- ção de uma cutĂcula defeituosa. Os cabelos sĂŁo quebradiços e nĂŁo excedem poucos centĂmetros de comprimento. O couro cabeludo Ă© a regiĂŁo mais afetada e a apresentação clĂnica mais comum Ă© alopecia associada Ă queratose folicular2,3. O diagnĂłstico Ă© clĂnico e a tricoscopia evidencia alteraçÔes moniliformes (alternĂąncia entre bandas largas e estreitas
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
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