1,292 research outputs found
Molecular cytogenetic mapping of Cucumis sativus and C. melo using highly repetitive DNA sequences
Chromosomes often serve as one of the most important molecular aspects of studying the evolution of species. Indeed, most of the crucial mutations that led to differentiation of species during the evolution have occurred at the chromosomal level. Furthermore, the analysis of pachytene chromosomes appears to be an invaluable tool for the study of evolution due to its effectiveness in chromosome identification and precise physical gene mapping. By applying fluorescence in situ hybridization of 45S rDNA and CsCent1 probes to cucumber pachytene chromosomes, here, we demonstrate that cucumber chromosomes 1 and 2 may have evolved from fusions of ancestral karyotype with chromosome number n= 12. This conclusion is further supported by the centromeric sequence similarity between cucumber and melon, which suggests that these sequences evolved from a common ancestor. It may be after or during speciation that these sequences were specifically amplified, after which they diverged and specific sequence variants were homogenized. Additionally, a structural change on the centromeric region of cucumber chromosome 4 was revealed by fiber-FISH using the mitochondrial-related repetitive sequences, BAC-E38 and CsCent1. These showed the former sequences being integrated into the latter in multiple regions. The data presented here are useful resources for comparative genomics and cytogenetics of Cucumis and, in particular, the ongoing genome sequencing project of cucumbe
Enhancement of electrical properties in Al-doped ZnO films by tuning dc bias voltage during radio frequency magnetron sputtering
Al-doped ZnO (AZO) thin films were deposited at room temperature on glass substrates by rf magnetron sputtering with simultaneous dc bias through an external inductor coil. The deposition rates of AZO films deposited using simultaneous rf and dc power along with an inductor coil were 20 higher than those deposited using only rf power. The effects of simultaneous rf and dc bias voltage during the deposition of AZO films were investigated in terms of their resistivity and compressive stress. It was observed that the AZO films deposited at 120 W rf power with 600 μH inductor coil exhibit the lowest resistivity of 6.71 à 10-4 Ïṡcm. © 2012 Elsevier B.V. All rights reserved
TeV scale partial mirage unification and neutralino dark matter
We study the TeV scale partial mirage unification scenario, where the gluino
and wino masses are degenerate around a TeV scale, but the bino mass is not
degenerate. This scenario has phenomenologically interesting aspects. First,
because of the degeneracy between the gluino and wino masses, this scenario
does not have the little hierarchy problem, that is, the higgisino mass is
around 150 GeV. The lightest superparticle is a mixture of the bino and
higgsino, and can lead to a right amount of thermal relic density as a dark
matter candidate
Modeling of Ultra Low Capacitance Transient Voltage Suppression Diode for High ESD Protection
To improve key properties such as ultra-low capacitance (ULC) and high-voltage (HV) breakdown, we have performed a simulation work about transient voltage suppression (TVS) diodes. ULC-TVS diode was designed to employ a double deep trench to cut off the various parasitic effects that may degrade the device performance. The electrostatic discharge (ESD) protection is the targeting for the best applications in high-frequency and high-speed ICs. In this work, the device could present excellent performance in terms of very responsive ESD properties, high breakdown voltage, low leakage current, and very low capacitance level. The double trenches are aligned to the top electrode contact to restrict field crowding effects by the strong electric field intensity. The performance would be sufficient for the robust ESD nature up to IEC61000-4-2 (30 kV) and compatible with strong surge protection IEC61000-4-5 (10A). Their electrical properties have been evaluated for structure from simulation and the results are obtained at the device parameters. Several process of device design related effects on the electrical capability and can be optimized. Keywords: ULC-TVS diode, simulation (TCAD), characteristics, capacitance, ESD protection
Bistable Organic Memory Device with Gold Nanoparticles Embedded in a Conducting Poly(N-vinylcarbazole) Colloids Hybrid
We report on the nonvolatile memory characteristics of a bistable organic memory (BOM) device with Au nanopartides (NPs) embedded in a conducting poly(N-vinylcarbazole) (PVK) colloids hybrid layer deposited on flexible poly(ethylenete-rephthalate) (PET) substrates. Transmission electron microscopy (TEM) images show the Au nanoparticles distributed isotropically around the surface of a PVK colloid. The average induced charge on Au nanoparticles, estimated using the C-V hysteresis curve, was large, as much as 5 holes/NP at a sweeping voltage of +/-3 V. The maximum ON/OFF ratio of the current bistability in the BOM devices was as large as 1 x 10(5). The cycling endurance tests of the ON/OFF switching exhibited a high endurance of above 1.5 x 10(5) cycles, and a high ON/OFF ratio of similar to 10(5) could be achieved consistently even after quite a long retention time of more than 1 x 10(6) s. To clarify the memory mechanism of the hole-mediated bistable organic memory device, the interactions between Au nanoparticles and poly(N-vinylcarbazole) colloids was studied by estimating the density of states and projected density of state calculations using density functional theory. Au atom interactions with a PVK unit decreased the band gap by 2.96 eV with the new induced gap states at 5.11 eV (HOMO, E(0)) and LUMO 4.30 eV and relaxed the HOMO level by 0.5 eV (E(1)). E(1) at similar to 6.2 eV is very close to the pristine HOMO, and thus the trapped hole in E(1) could move to the HOMO of pristine PVK From the experimental data and theoretical calculation, it was revealed that a low-conductivity state resulted from a hole trapping at E(o) and E(1) states and subsequent hole transportation through Fowler-Nordheim tunneling from E(1) state to Au NPs and/or interface trap states leads to a high conductivity state
Evolution of fNL to the adiabatic limit
We study inflationary perturbations in multiple-field models, for which zeta
typically evolves until all isocurvature modes decay--the "adiabatic limit". We
use numerical methods to explore the sensitivity of the nonlinear parameter fNL
to the process by which this limit is achieved, finding an appreciable
dependence on model-specific data such as the time at which slow-roll breaks
down or the timescale of reheating. In models with a sum-separable potential
where the isocurvature modes decay before the end of the slow-roll phase we
give an analytic criterion for the asymptotic value of fNL to be large. Other
examples can be constructed using a waterfall field to terminate inflation
while fNL is transiently large, caused by descent from a ridge or convergence
into a valley. We show that these two types of evolution are distinguished by
the sign of the bispectrum, and give approximate expressions for the peak fNL.Comment: v1: 25 pages, plus Appendix and bibliography, 6 figures. v2: minor
edits to match published version in JCA
Large non-Gaussianity from two-component hybrid inflation
We study the generation of non-Gaussianity in models of hybrid inflation with
two inflaton fields, (2-brid inflation). We analyse the region in the parameter
and the initial condition space where a large non-Gaussianity may be generated
during slow-roll inflation which is generally characterised by a large f_NL,
tau_NL and a small g_NL. For certain parameter values we can satisfy
tau_NL>>f_NL^2. The bispectrum is of the local type but may have a significant
scale dependence. We show that the loop corrections to the power spectrum and
bispectrum are suppressed during inflation, if one assume that the fields
follow a classical background trajectory. We also include the effect of the
waterfall field, which can lead to a significant change in the observables
after the waterfall field is destabilised, depending on the couplings between
the waterfall and inflaton fields.Comment: 16 pages, 6 figures; v2: comments and references added, typos
corrected, matches published versio
Density Fluctuations in Thermal Inflation and Non-Gaussianity
We consider primordial fluctuations in thermal inflation scenario. Since the
thermal inflation drives about 10 -folds after the standard inflation, the
time of horizon-exit during inflation corresponding to the present
observational scale shifts toward the end of inflation. It generally makes the
primordial power spectrum more deviated from a scale-invariant one and hence
renders some models inconsistent with observations. We present a mechanism of
generating the primordial curvature perturbation at the end of thermal
inflation utilizing a fluctuating coupling of a flaton field with the fields in
thermal bath. We show that, by adopting the mechanism, some inflation models
can be liberated even in the presence of the thermal inflation. We also discuss
non-Gaussianity in the mechanism and show that large non-Gaussianity can be
generated in this scenario.Comment: 15 pages, 1 figures, minor change
General treatment of isocurvature perturbations and non-Gaussianities
We present a general formalism that provides a systematic computation of the
linear and non-linear perturbations for an arbitrary number of cosmological
fluids in the early Universe going through various transitions, in particular
the decay of some species (such as a curvaton or a modulus). Using this
formalism, we revisit the question of isocurvature non-Gaussianities in the
mixed inflaton-curvaton scenario and show that one can obtain significant
non-Gaussianities dominated by the isocurvature mode while satisfying the
present constraints on the isocurvature contribution in the observed power
spectrum. We also study two-curvaton scenarios, taking into account the
production of dark matter, and investigate in which cases significant
non-Gaussianities can be produced.Comment: Substantial improvements with respect to the first version. In
particular, we added a discussion on the confrontation of the models with
future observational data. This version is accepted for publication in JCA
Spectral Index and Non-Gaussianity in Supersymmetric Hybrid Inflation
We consider a supersymmetric hybrid inflation model with two inflaton fields.
The superpotential during inflation is dominated by W=(\kappa S+\kappa' S')M^2,
where S, S' are inflatons carrying the same U(1)_R charge, \kappa, \kappa' are
dimensionless couplings, and M (\sim 10^{15-16} GeV) is a dimensionful
parameter associated with a symmetry breaking scale. One light mass eigenstate
drives inflation, while the other heavier mass eigenstate is stuck to the
origin. The smallness of the lighter inflaton mass for the scalar spectral
index n_s\approx 0.96, which is the center value of WMAP7, can be controlled by
the ratio \kappa'/\kappa through the supergravity corrections. We also discuss
the possibility of the two field inflation and large non-Gaussianity in this
setup.Comment: 17 pages, 2 figures, version published in Eur. Phys. J.
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