116 research outputs found
Low energy cluster beam deposited BN films as the cascade for Field Emission
The atomic deposited BN films with the thickness of nanometers (ABN) were
prepared by radio frequency magnetron sputtering method and the nanostructured
BN films (CBN) were prepared by Low Energy Cluster Beam Deposition. UV-Vis
Absorption measurement proves the band gap of 4.27eV and field emission of the
BN films were carried out. F-N plots of all the samples give a good fitting and
demonstrate the F-N tunneling of the emission process. The emission of ABN
begins at the electric field of 14.6 V/{\mu}m while that of CBN starts at
5.10V/{\mu}m. Emission current density of 1mA/cm2 for ABN needs the field of
20V/{\mu}m while that of CBN needs only 12.1V/{\mu}m. The cluster-deposited BN
on n-type Silicon substrate proves a good performance in terms of the lower
gauge voltage, more emission sites and higher electron intensity and seems a
promising substitute for the cascade of Field Emission
Statistics of leading digits leads to unification of quantum correlations
We show that the frequency distribution of the first significant digits of
the numbers in the data sets generated from a large class of measures of
quantum correlations, which are either entanglement measures, or belong to the
information-theoretic paradigm, exhibit a universal behaviour. In particular,
for Haar uniformly simulated arbitrary two-qubit states, we find that the
first-digit distribution corresponding to a collection of chosen computable
quantum correlation quantifiers tend to follow the first-digit law, known as
the Benford's law, when the rank of the states increases. Considering a
two-qubit state which is obtained from a system governed by paradigmatic spin
Hamiltonians, namely, the XY model in a transverse field, and the XXZ model, we
show that entanglement as well as information theoretic measures violate the
Benford's law. We quantitatively discuss the violation of the Benford's law by
using a violation parameter, and demonstrate that the violation parameter can
signal quantum phase transitions occurring in these models. We also comment on
the universality of the statistics of first significant digits corresponding to
appropriate measures of quantum correlations in the case of multipartite
systems as well as systems in higher dimensions.Comment: v1: 11 pages, 5 figures, 2 tables; v2: 11 pages, 6 figures, 2 tables,
new results added, extended version of the published pape
The Carnegie Supernova Project I: photometry data release of low-redshift stripped-envelope supernovae
The first phase of the Carnegie Supernova Project (CSP-I) was a dedicated
supernova follow-up program based at the Las Campanas Observatory that
collected science data of young, low-redshift supernovae between 2004 and 2009.
Presented in this paper is the CSP-I photometric data release of low-redshift
stripped-envelope core-collapse supernovae. The data consist of optical
(uBgVri) photometry of 34 objects, with a subset of 26 having near-infrared
(YJH) photometry. Twenty objects have optical pre-maximum coverage with a
subset of 12 beginning at least five days prior to the epoch of B-band maximum
brightness. In the near-infrared, 17 objects have pre-maximum observations with
a subset of 14 beginning at least five days prior to the epoch of J-band
maximum brightness. Analysis of this photometric data release is presented in
companion papers focusing on techniques to estimate host-galaxy extinction
(Stritzinger et al., submitted) and the light-curve and progenitor star
properties of the sample (Taddia et al., submitted). The analysis of an
accompanying visual-wavelength spectroscopy sample of ~150 spectra will be the
subject of a future paper.Comment: Updated a couple of small error
The Carnegie Supernova Project. I. Third Photometry Data Release of Low-redshift Type Ia Supernovae and Other White Dwarf Explosions
We present final natural-system optical (ugriBV) and near-infrared (YJH) photometry of 134 supernovae (SNe) with probable white dwarf progenitors that were observed in 2004-2009 as part of the first stage of the Carnegie Supernova Project (CSP-I). The sample consists of 123 Type Ia SNe, 5 Type Iax SNe, 2 super-Chandrasekhar SN candidates, 2 Type Ia SNe interacting with circumstellar matter, and 2 SN 2006bt-like events. The redshifts of the objects range from to 0.0835; the median redshift is 0.0241. For 120 (90%) of these SNe, near-infrared photometry was obtained. Average optical extinction coefficients and color terms are derived and demonstrated to be stable during the five CSP-I observing campaigns. Measurements of the CSP-I near-infrared bandpasses are also described, and near-infrared color terms are estimated through synthetic photometry of stellar atmosphere models. Optical and near-infrared magnitudes of local sequences of tertiary standard stars for each supernova are given, and a new calibration of Y-band magnitudes of the Persson et al. standards in the CSP-I natural system is presented.Fil: Krisciunas, Kevin. Texas A&M University; Estados UnidosFil: Contreras, Carlos. University Aarhus; Dinamarca. Las Campanas Observatory; ChileFil: Burns, Christopher R.. Las Campanas Observatory; ChileFil: Phillips, M. M.. Las Campanas Observatory; ChileFil: Stritzinger, Maximilian D.. Las Campanas Observatory; Chile. University Aarhus; DinamarcaFil: Morrell, Nidia Irene. Las Campanas Observatory; ChileFil: Hamuy, Mario. Universidad de Chile; ChileFil: Anais, Jorge. Las Campanas Observatory; ChileFil: Boldt, Luis. Las Campanas Observatory; ChileFil: Busta, Luis. Las Campanas Observatory; ChileFil: Campillay, Abdo. Las Campanas Observatory; ChileFil: Castellón, Sergio. Las Campanas Observatory; ChileFil: Folatelli, Gaston. Las Campanas Observatory; Chile. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Freedman, Wendy L.. University of Chicago; Estados UnidosFil: González, Consuelo. Las Campanas Observatory; ChileFil: Hsiao, Eric Y.. Florida State University; Estados Unidos. University Aarhus; Dinamarca. Las Campanas Observatory; ChileFil: Krzeminski, Wojtek. Las Campanas Observatory; ChileFil: Persson, Sven Eric. Carnegie Observatories;Fil: Roth, Miguel. Gmto Corporation; Chile. Las Campanas Observatory; ChileFil: Salgado, Francisco. Leiden Observatory Research Institute; . Las Campanas Observatory; ChileFil: Serón, Jacqueline. Las Campanas Observatory; Chile. Cerro Tololo Inter American Observatory; ChileFil: Suntzeff, Nicholas B.. Texas A&M University; Estados UnidosFil: Torres, Simón. Soar Telescope; Chile. Las Campanas Observatory; ChileFil: Filippenko, Alexei V.. University of California at Berkeley; Estados UnidosFil: Li, Weidong. University of California at Berkeley; Estados UnidosFil: Madore, Barry F.. Jet Propulsion Laboratory, California Institute Of Technology; . Las Campanas Observatory; ChileFil: DePoy, D.L.. Texas A&M University; Estados UnidosFil: Marshall, Jennifer L.. Texas A&M University; Estados UnidosFil: Rheault, Jean Philippe. Texas A&M University; Estados UnidosFil: Villanueva, Steven. Texas A&M University; Estados Unidos. Ohio State University; Estados Unido
Neuromuscular effects of G93A-SOD1 expression in zebrafish
Abstract
Background
Amyotrophic lateral sclerosis (ALS) is a fatal disorder involving the degeneration and loss of motor neurons. The mechanisms of motor neuron loss in ALS are unknown and there are no effective treatments. Defects in the distal axon and at the neuromuscular junction are early events in the disease course, and zebrafish provide a promising in vivo system to examine cellular mechanisms and treatments for these events in ALS pathogenesis.
Results
We demonstrate that transient genetic manipulation of zebrafish to express G93A-SOD1, a mutation associated with familial ALS, results in early defects in motor neuron outgrowth and axonal branching. This is consistent with previous reports on motor neuron axonal defects associated with familial ALS genes following knockdown or mutant protein overexpression. We also demonstrate that upregulation of growth factor signaling is capable of rescuing these early defects, validating the potential of the model for therapeutic discovery. We generated stable transgenic zebrafish lines expressing G93A-SOD1 to further characterize the consequences of G93A-SOD1 expression on neuromuscular pathology and disease progression. Behavioral monitoring reveals evidence of motor dysfunction and decreased activity in transgenic ALS zebrafish. Examination of neuromuscular and neuronal pathology throughout the disease course reveals a loss of neuromuscular junctions and alterations in motor neuron innervations patterns with disease progression. Finally, motor neuron cell loss is evident later in the disease.
Conclusions
This sequence of events reflects the stepwise mechanisms of degeneration in ALS, and provides a novel model for mechanistic discovery and therapeutic development for neuromuscular degeneration in ALS.http://deepblue.lib.umich.edu/bitstream/2027.42/112892/1/13024_2012_Article_367.pd
Carnegie Supernova Project-II: Extending the Near-Infrared Hubble Diagram for Type Ia Supernovae to
The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year
program to obtain optical and near-infrared observations of a "Cosmology"
sample of Type Ia supernovae located in the smooth Hubble flow (). Light curves were also obtained of a "Physics"
sample composed of 90 nearby Type Ia supernovae at selected for
near-infrared spectroscopic time-series observations. The primary emphasis of
the CSP-II is to use the combination of optical and near-infrared photometry to
achieve a distance precision of better than 5%. In this paper, details of the
supernova sample, the observational strategy, and the characteristics of the
photometric data are provided. In a companion paper, the near-infrared
spectroscopy component of the project is presented.Comment: 43 pages, 10 figures, accepted for publication in PAS
Measurement of w-InN/h-BN Heterojunction Band Offsets by X-Ray Photoemission Spectroscopy
X-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being −0.30 ± 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 ± 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices
The Carnegie Supernova Project II. The shock wave revealed through the fog: The strongly interacting Type IIn SN 2013L
We present ultra-violet to mid-infrared observations of the long-lasting Type
IIn supernova (SN) 2013L obtained by the Carnegie Supernova Project II
(CSP-II). The spectra of SN 2013L are dominated by H emission features
characterized by three components attributed to different regions. A unique
feature of this Type IIn SN is that the blue shifted line profile is dominated
by the macroscopic velocity of the expanding shock wave of the SN. We are
therefore able to trace the evolution of the shock velocity in the dense and
partially opaque circumstellar medium (CSM), from at +48
d, decreasing as to after a year. We perform
spectral modeling of both the broad- and intermediate-velocity components of
the H line profile. The high-velocity component is consistent with
emission from a radially thin, spherical shell located behind the expanding
shock with emission wings broadened by electron scattering. We propose that the
intermediate component originates from pre-ionized gas from the unshocked dense
CSM with the same velocity as the narrow component, , but
also broadened by electron scattering. The spectral energy distributions (SEDs)
of SN 2013L after +132 d are well reproduced by a two-component black-body (BB)
model. The circumstellar-interaction model of the bolometric light curve
reveals a mass-loss rate history with large values () over the 25 - 40 years before explosion. The drop
in the light curve at days and presence of electron scattering wings
at late epochs indicate an anisotropic CSM. The mass-loss rate values and the
unshocked CSM velocity are consistent with the characteristics of a massive
star, such as a luminous blue variable (LBV) undergoing strong eruptions,
similar to Carina.Comment: Replaced after language editor corrections, accepted for publication
on Astronomy and Astrophysics, 43 pages, 29 figures. Abstract abridge
Carnegie Supernova Project: The First Homogeneous Sample of Super-Chandrasekhar-mass/2003fg-like Type Ia Supernovae
We present a multiwavelength photometric and spectroscopic analysis of 13 super-Chandrasekhar-mass/2003fg-like Type Ia supernovae (SNe Ia). Nine of these objects were observed by the Carnegie Supernova Project. The 2003fg-like SNe have slowly declining light curves (Δm 15(B) < 1.3 mag), and peak absolute B-band magnitudes of -19 < M B < -21 mag. Many of the 2003fg-like SNe are located in the same part of the luminosity-width relation as normal SNe Ia. In the optical B and V bands, the 2003fg-like SNe look like normal SNe Ia, but at redder wavelengths they diverge. Unlike other luminous SNe Ia, the 2003fg-like SNe generally have only one i-band maximum, which peaks after the epoch of the B-band maximum, while their near-IR (NIR) light-curve rise times can be ⪆40 days longer than those of normal SNe Ia. They are also at least 1 mag brighter in the NIR bands than normal SNe Ia, peaking above M H = -19 mag, and generally have negative Hubble residuals, which may be the cause of some systematics in dark-energy experiments. Spectroscopically, the 2003fg-like SNe exhibit peculiarities such as unburnt carbon well past maximum light, a large spread (8000-12,000 km s-1) in Si ii λ6355 velocities at maximum light with no rapid early velocity decline, and no clear H-band break at +10 days. We find that SNe with a larger pseudo-equivalent width of C ii at maximum light have lower Si ii λ6355 velocities and more slowly declining light curves. There are also multiple factors that contribute to the peak luminosity of 2003fg-like SNe. The explosion of a C-O degenerate core inside a carbon-rich envelope is consistent with these observations. Such a configuration may come from the core-degenerate scenario.Fil: Ashall, C.. University Hawaii Institute For Astronomy; Estados UnidosFil: Lu, J.. Florida State University; Estados UnidosFil: Hsiao, E. Y.. Florida State University; Estados UnidosFil: Hoeflich, P.. Florida State University; Estados UnidosFil: Phillips, M. M.. Las Campanas Observatory; ChileFil: Galbany, Lluís. Instituto de Ciencias del Espacio; EspañaFil: Burns, C. R.. Las Campanas Observatory; ChileFil: Contreras, C.. Las Campanas Observatory; ChileFil: Krisciunas, K.. Texas A&M University; Estados UnidosFil: Morrell, Nidia Irene. Las Campanas Observatory; ChileFil: Stritzinger, M. D.. University Aarhus; DinamarcaFil: Suntzeff, Nicholas B.. Texas A&M University; Estados UnidosFil: Taddia, F.. University Aarhus; DinamarcaFil: Anais, J.. Las Campanas Observatory; ChileFil: Baron, E.. Oklahoma State University; Estados Unidos. Universitat Hamburg; AlemaniaFil: Brown, P. J.. Texas A&M University; Estados UnidosFil: Busta, L.. Las Campanas Observatory; ChileFil: Campillay, A.. Universidad de La Serena; ChileFil: Castellón, S.. Las Campanas Observatory; ChileFil: Corco, C.. Las Campanas Observatory; Chile. Soar Telescope; ChileFil: Davis, S.. University of California at Davis; Estados UnidosFil: Folatelli, Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Förster, F.. Universidad de Chile; Chile. Instituto Milenio de Astrofísica; ChileFil: Freedman, W. L.. University of Chicago; Estados UnidosFil: Gonzaléz, C.. Las Campanas Observatory; ChileFil: Hamuy, M.. Universidad de Chile; ChileFil: Holmbo, S.. University Aarhus; DinamarcaFil: Kirshner, R. P.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Kumar, S.. Florida State University; Estados UnidosFil: Marion, G. H.. University of Texas at Austin; Estados UnidosFil: Mazzali, P.. Liverpool John Moores University; Reino UnidoFil: Morokuma, T.. The University Of Tokyo; JapónFil: Nugent, P. E.. Lawrence Berkeley National Laboratory; Estados Unidos. University of California at Berkeley; Estados UnidosFil: Persson, S. E.. Las Campanas Observatory; ChileFil: Piro, A. L.. Las Campanas Observatory; ChileFil: Roth, M.. Las Campanas Observatory; ChileFil: Salgado, F.. Las Campanas Observatory; ChileFil: Sand, D.J.. University of Arizona; Estados UnidosFil: Seron, J.. Las Campanas Observatory; ChileFil: Shahbandeh, M.. Florida State University; Estados UnidosFil: Shappee, B. J.. University Hawaii Institute For Astronomy; Estados Unido
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