1,156 research outputs found
Acceleration Of Protons To Above 6 MeV Using H2O >Snow> Nanowire Targets
A scheme is presented for using H2O >snow> nanowire targets for the generation of fast protons. This novel method may relax the requirements for very high laser intensities, thus reducing the size and cost of laser based ion acceleration system.Physic
DspaceOgre 3D Graphics Visualization Tool
This general-purpose 3D graphics visualization C++ tool is designed for visualization of simulation and analysis data for articulated mechanisms. Examples of such systems are vehicles, robotic arms, biomechanics models, and biomolecular structures. DspaceOgre builds upon the open-source Ogre3D graphics visualization library. It provides additional classes to support the management of complex scenes involving multiple viewpoints and different scene groups, and can be used as a remote graphics server. This software provides improved support for adding programs at the graphics processing unit (GPU) level for improved performance. It also improves upon the messaging interface it exposes for use as a visualization server
Rectification Mechanism in Di-Block Oligomer Molecular Diodes
We investigated a mechanism of rectification in di-block oligomer diode
molecules that have recently been synthesized and showed a pronounced asymmetry
in the measured I-V spectrum. The observed rectification effect is due to the
resonant nature of electron transfer in the system and localization properties
of bound state wave functions of resonant states of the tunneling electron
interacting with asymmetric molecule in an electric field. The asymmetry of the
tunneling wave function is enhanced or weakened depending on the polarity of
applied bias. The conceptually new theoretical approach, the Green's function
theory of sub-barrier scattering, is able to provide a physically transparent
explanation of this rectification effect based on the concept of the bound
state spectrum of a tunneling electron. The theory predicts the characteristic
features of the I-V spectrum in qualitative agreement with experiment
Hard Photodisintegration of a Proton Pair
We present a study of high energy photodisintegration of proton-pairs through the γ + 3He → p + p + n channel. Photon energies, Eγ , from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s−11 scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. For Eγ below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration
Developmental, cellular, and biochemical basis of transparency in the glasswing butterfly Greta oto
Numerous species of Lepidoptera have transparent wings, which often possess scales of altered morphology and reduced size, and the presence of membrane surface nanostructures that dramatically reduce reflection. Optical properties and anti-reflective nanostructures have been characterized for several ‘clearwing’ Lepidoptera, but the developmental basis of wing transparency is unknown. We apply confocal and electron microscopy to create a developmental time-series in the glasswing butterfly, Greta oto, comparing transparent and non-transparent wing regions. We find that scale precursor cell density is reduced in transparent regions, and cytoskeletal organization differs between flat scales in opaque regions, and thin, bristle-like scales in transparent regions. We also reveal that sub-wavelength nanopillars on the wing membrane are wax-based, derive from wing epithelial cells and their associated microvillar projections, and demonstrate their role in enhancing-anti-reflective properties. These findings provide insight into morphogenesis of naturally organized micro- and nanostructures and may provide bioinspiration for new anti-reflective materials
Switching between different vortex states in 2-dimensional easy-plane magnets due to an ac magnetic field
Using a discrete model of 2-dimensional easy-plane classical ferromagnets, we
propose that a rotating magnetic field in the easy plane can switch a vortex
from one polarization to the opposite one if the amplitude exceeds a threshold
value, but the backward process does not occur. Such switches are indeed
observed in computer simulations.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Transition between nuclear and quark-gluon descriptions of hadrons and light nuclei
We provide a perspective on studies aimed at observing the transition between
hadronic and quark-gluonic descriptions of reactions involving light nuclei. We
begin by summarizing the results for relatively simple reactions such as the
pion form factor and the neutral pion transition form factor as well as that
for the nucleon and end with exclusive photoreactions in our simplest nuclei. A
particular focus will be on reactions involving the deuteron. It is noted that
a firm understanding of these issues is essential for unraveling important
structure information from processes such as deeply virtual Compton scattering
as well as deeply virtual meson production. The connection to exotic phenomena
such as color transparency will be discussed. A number of outstanding
challenges will require new experiments at modern facilities on the horizon as
well as further theoretical developments.Comment: 37 pages, 17 figures, submitted to Reports on Progress in Physic
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