2,146 research outputs found
Effect of next-nearest neighbor coupling on the optical spectra in bilayer graphene
We investigate the dependence of the optical conductivity of bilayer graphene
(BLG) on the intra- and inter-layer interactions using the most complete model
to date. We show that the next nearest-neighbor intralayer coupling introduces
new features in the low-energy spectrum that are highly sensitive to sample
doping, changing significantly the ``universal'' conductance. Further, its
interplay with interlayer couplings leads to an anisotropy in conductance in
the ultraviolet range. We propose that experimental measurement of the optical
conductivity of intrinsic and doped BLG will provide a good benchmark for the
relative importance of intra- and inter-layer couplings at different doping
levels.Comment: 5 pages, 5 figure
Spatial coherence measurement of a high average power table-top soft X-ray laser
Includes bibliographical references (page 126).An extraordinarily high degree of spatial coherence from a high average power tabletop 46.9 nm laser was observed in two-pinhole interference experiments. Refractive anti-guiding and gain guiding along a capillary discharge-produced plasma column causes a rapid increase of the spatial coherence with amplifier length. Full spatial coherence was approached with a 36 cm long plasma of very high axial uniformity and a length to diameter ratio exceeding 1000: 1
Asymptotic Normalization Coefficients for 13C+p->14N
The proton exchange reaction has been measured
at an incident energy of 162 MeV. Angular distributions were obtained for
proton transfer to the ground and low lying excited states in . Elastic
scattering of on also was measured out to the rainbow angle
region in order to find reliable optical model potentials. Asymptotic
normalization coefficients for the system have been
found for the ground state and the excited states at 2.313, 3.948, 5.106 and
5.834 MeV in . These asymptotic normalization coefficients will be used
in a determination of the S-factor for at solar
energies from a measurement of the proton transfer reaction
.Comment: 5 pages, 6 figure
Can Disruption of Basal Ganglia-Thalamocortical Circuit in Wilson Disease Be Associated with Juvenile Myoclonic Epilepsy Phenotype?
In this paper, we describe the multimodal MRI findings in a patient with Wilson disease and a seizure disorder, characterized by an electroclinical picture resembling juvenile myoclonic epilepsy. The brain structural MRI showed a deposition of ferromagnetic materials in the basal ganglia, with marked hypointensities in T2-weighted images of globus pallidus internus bilaterally. A resting-state fMRI study revealed increased functional connectivity in the patient, compared to control subjects, in the following networks: (1) between the primary motor cortex and several cortical regions, including the secondary somatosensory cortex and (2) between the globus pallidus and the thalamo-frontal network. These findings suggest that globus pallidus alterations, due to metal accumulation, can lead to a reduction in the normal globus pallidus inhibitory tone on the thalamo-(motor)-cortical pathway. This, in turn, can result in hyperconnectivity in the motor cortex circuitry, leading to myoclonus and tonic-clonic seizures. We suppose that, in this patient, Wilson disease generated a ‘lesion model’ of myoclonic epilepsy
Intrinsic response time of graphene photodetectors
Graphene-based photodetectors are promising new devices for high-speed
optoelectronic applications. However, despite recent efforts, it is not clear
what determines the ultimate speed limit of these devices. Here, we present
measurements of the intrinsic response time of metal-graphene-metal
photodetectors with monolayer graphene using an optical correlation technique
with ultrashort laser pulses. We obtain a response time of 2.1 ps that is
mainly given by the short lifetime of the photogenerated carriers. This time
translates into a bandwidth of ~262 GHz. Moreover, we investigate the
dependence of the response time on gate voltage and illumination laser power
Variabilidade genética entre javalis (sus scrofa scrofa), híbridos e suínos por meio de marcadores microssatélites.
Os híbridos entre javalis e suínos é bastante comum. Assim, tem-se detectado polimorfismo em javalis, variando o número de cromossomos de 36 a 38. No experimento foram utilizados os animais agrupados em 5 grupos genéticos: grupo I - 59 suínos domésticos com 2n = 38; grupo II - 46 javalis puros de origem (PO) com 2n = 36; grupo III - 6 híbridos, com 2n=36; grupo IV - 30 híbridos com 2n=37 e grupo V - 10 híbridos com 2n=38. O DNA genômico foi extraído e, posteriormente, amplificou-se, pela técnica de PCR, os fragmentos desses microssatélites - IGF1, ACTG2, TNFB -, os quais foram desenvolvidos para a subespécie Sus scrofa domestica. O objetivo do presente trabalho foi avaliar a heterozigosidade esperada (He) e observada (Ho) e o coeficiente de endogamia (FIS) dentro de cada população e testar as relações existentes entre os cinco grupos genéticos para estabelecer a distância genética entre eles. Os valores médios de heterozigosidades variaram 0,537-0,7871 e apresentam-se inferiores aos valores médios de heterozigosidades esperadas (0,6749-0,8279).Os valores de FIS para os Grupos II e III foram negativos, -0,005 e -0,037 respectivamente nestas populações. Nos demais grupos os valores de FIS foram positivos
Eight weddings and six funerals: An fMRI study on autobiographical memories
\u201cAutobiographical memory\u201d (AM) refers to remote memories from one's own life. Previous neuroimaging studies have highlighted that voluntary retrieval processes from AM involve different forms of memory and cognitive functions. Thus, a complex and widespread brain functional network has been found to support AM. The present functional magnetic resonance imaging (fMRI) study used a multivariate approach to determine whether neural activity within the AM circuit would recognize memories of real autobiographical events, and to evaluate individual differences in the recruitment of this network. Fourteen right-handed females took part in the study. During scanning, subjects were presented with sentences representing a detail of a highly emotional real event (positive or negative) and were asked to indicate whether the sentence described something that had or had not really happened to them. Group analysis showed a set of cortical areas able to discriminate the truthfulness of the recalled events: medial prefrontal cortex, posterior cingulate/retrosplenial cortex, precuneus, bilateral angular, superior frontal gyri, and early visual cortical areas. Single-subject results showed that the decoding occurred at different time points. No differences were found between recalling a positive or a negative event. Our results show that the entire AM network is engaged in monitoring the veracity of AMs. This process is not affected by the emotional valence of the experience but rather by individual differences in cognitive strategies used to retrieve AMs
Photo-disintegration cross section measurements on W, Re and Os: Implications for the Re-Os cosmochronology
Cross sections of the W, Re, Os() reactions
were measured using quasi-monochromatic photon beams from laser Compton
scattering (LCS) with average energies from 7.3 to 10.9 MeV. The results are
compared with the predictions of Hauser-Feshbach statistical calculations using
four different sets of input parameters. In addition, the inverse neutron
capture cross sections were evaluated by constraining the model parameters,
especially the strength function, on the basis of the experimental data.
The present experiment helps to further constrain the correction factor
for the neutron capture on the 9.75 keV state in Os.
Implications of to the Re-Os cosmochronology are discussed with a
focus on the uncertainty in the estimate of the age of the Galaxy.Comment: 11 page
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