2,145 research outputs found
Baseline tests of the EVA change-of-pace coupe electric passenger vehicle
The EVA Change-of-Pace Coupe, is an electric passenger vehicle, to characterize the state-of-the-art of electric vehicles. The EVA Change-of-Pace Coupe is a four passenger sedan that has been coverted to an electric vehicle. It is powered by twenty 6 volt traction batteries through a silicon controlled rectifier chopper controller actuated by a foot throttle to change the voltage applied to the series wound, direct current motor. Braking is accomplished with a vacuum assist hydraulic braking system. Regenerative braking is also provided
Galaxy UV-luminosity function and reionization constraints on axion dark matter
If the dark matter (DM) were composed of axions, then structure formation in
the Universe would be suppressed below the axion Jeans scale. Using an analytic
model for the halo mass function of a mixed DM model with axions and cold dark
matter, combined with the abundance-matching technique, we construct the
UV-luminosity function. Axions suppress high- galaxy formation and the
UV-luminosity function is truncated at a faintest limiting magnitude. From the
UV-luminosity function, we predict the reionization history of the universe and
find that axion DM causes reionization to occur at lower redshift. We search
for evidence of axions using the Hubble Ultra Deep Field UV-luminosity function
in the redshift range -, and the optical depth to reionization,
, as measured from cosmic microwave background polarization. All probes
we consider consistently exclude from
contributing more than half of the DM, with our strongest constraint ruling
this model out at more than significance. In conservative models of
reionization a dominant component of DM with is in
tension with the measured value of , putting pressure on an
axion solution to the cusp-core problem. Tension is reduced to for
the axion contributing only half of the DM. A future measurement of the
UV-luminosity function in the range - by JWST would provide further
evidence for or against . Probing still higher masses
of will be possible using future measurements of the
kinetic Sunyaev-Zel'dovich effect by Advanced ACTPol to constrain the time and
duration of reionization.Comment: 17 pages, 8 figures, 2 tables. v2: Minor Changes. References added.
Published in MNRA
Non-locality in the nucleon-nucleon interaction and nuclear matter saturation
We study the possible relationship between the saturation properties of
nuclear matter and the inclusion of non-locality in the nucleon-nucleon
interaction. To this purpose we compute the saturation curve of nuclear matter
within the Bethe-Brueckner-Goldstone theory using a recently proposed realistic
non-local potential, and compare it with the corresponding curves obtained with
a purely local realistic interaction (Argonne v) and the most recent
version of the one-boson exchange potential (CD Bonn). We find that the
inclusion of non-locality in the two-nucleon bare interaction strongly affects
saturation, but it is unable to provide a consistent description of few-body
nuclear systems and nuclear matter.Comment: 9 pages, 8 figures; v2: introduction extended, references added,
discussion of fig.8 reformulated; to be published in Phys. Rev.
Baseline tests of the battronic Minivan electric delivery van
An electric passenger vehicle was tested to develop data characterizing the state of the art of electric and hybrid vehicles. The test measured vehicle maximum speed, range at constant speed, range over stop-and-go driving schedules, maximum acceleration, gradeability and limit, road energy consumption, road power, indicated energy consumption, braking capability and battery charge efficiency. The data obtained are to serve as a baseline to compare improvements in electric and hybrid vehicle technologies and to assist in establishing performance standards
Electrostatic Potential of Human Immunodeficiency Virus Type 2 and Rhesus Macaque Simian Immunodeficiency Virus Capsid Proteins
Human immunodeficiency virus type 2 (HIV-2) and simian immunodeficiency virus isolated from a macaque monkey (SIVmac) are assumed to have originated from simian immunodeficiency virus isolated from sooty mangabey (SIVsm). Despite their close similarity in genome structure, HIV-2 and SIVmac show different sensitivities to TRIM5α, a host restriction factor against retroviruses. The replication of HIV-2 strains is potently restricted by rhesus (Rh) monkey TRIM5α, while that of SIVmac strain 239 (SIVmac239) is not. Viral capsid protein is the determinant of this differential sensitivity to TRIM5α, as the HIV-2 mutant carrying SIVmac239 capsid protein evaded Rh TRIM5α-mediated restriction. However, the molecular determinants of this restriction mechanism are unknown. Electrostatic potential on the protein-binding site is one of the properties regulating protein–protein interactions. In this study, we investigated the electrostatic potential on the interaction surface of capsid protein of HIV-2 strain GH123 and SIVmac239. Although HIV-2 GH123 and SIVmac239 capsid proteins share more than 87% amino acid identity, we observed a large difference between the two molecules with the HIV-2 GH123 molecule having predominantly positive and SIVmac239 predominantly negative electrostatic potential on the surface of the loop between α-helices 4 and 5 (L4/5). As L4/5 is one of the major determinants of Rh TRIM5α sensitivity of these viruses, the present results suggest that the binding site of the Rh TRIM5α may show complementarity to the HIV-2 GH123 capsid surface charge distribution
A single amino acid substitution of the human immunodeficiency virus type 1 capsid protein affects viral sensitivity to TRIM5α
<p>Abstract</p> <p>Background</p> <p>Human immunodeficiency virus type 1 (HIV-1) productively infects only humans and chimpanzees but not Old World monkeys, such as rhesus and cynomolgus (CM) monkeys. To establish a monkey model of HIV-1/AIDS, several HIV-1 derivatives have been constructed. We previously reported that efficient replication of HIV-1 in CM cells was achieved after we replaced the loop between α-helices 6 and 7 (L6/7) of the capsid protein (CA) with that of SIVmac239 in addition to the loop between α-helices 4 and 5 (L4/5) and <it>vif</it>. This virus (NL-4/5S6/7SvifS) was supposed to escape from host restriction factors cyclophilin A, CM TRIM5α, and APOBEC3G. However, the replicative capability of NL-4/5S6/7SvifS in human cells was severely impaired.</p> <p>Results</p> <p>By long-term cultivation of human CEMss cells infected with NL-4/5S6/7SvifS, we succeeded in rescuing the impaired replicative capability of the virus in human cells. Sequence analysis of the CA region of the adapted virus revealed a G-to-E substitution at the 116th position of the CA (G116E). Introduction of this substitution into the molecular DNA clone of NL-4/5S6/7SvifS indeed improved the virus' replicative capability in human cells. Although the G116E substitution occurred during long-term cultivation of human cells infected with NL-4/5S6/7SvifS, the viruses with G116E unexpectedly became resistant to CM, but not human TRIM5α-mediated restriction. The 3-D model showed that position 116 is located in the 6<sup>th </sup>helix near L4/5 and L6/7 and is apparently exposed to the protein surface. The amino acid substitution at the 116<sup>th </sup>position caused a change in the structure of the protein surface because of the replacement of G (which has no side chain) with E (which has a long negatively charged side chain).</p> <p>Conclusions</p> <p>We succeeded in rescuing the impaired replicative capability of NL-4/5S6/7SvifS and report a mutation that improved the replicative capability of the virus. Unexpectedly, HIV-1 with this mutation became resistant to CM TRIM5α-mediated restriction.</p
Reconstruction of the time-dependent electronic wave packet arising from molecular autoionization
Autoionizing resonances are paradigmatic examples of two-path wave interferences between direct photoionization, which takes a few attoseconds, and ionization via quasi-bound states, which takes much longer. Time-resolving the evolution of these interferences has been a long-standing goal, achieved recently in the helium atom owing to progress in attosecond technologies. However, already for the hydrogen molecule, similar time imaging has remained beyond reach due to the complex interplay between fast nuclear and electronic motions. We show how vibrationally resolved photoelectron spectra of H2 allow one to reconstruct the associated subfemtosecond autoionization dynamics by using the ultrafast nuclear dynamics as an internal clock, thus forgoing ultrashort pulses. Our procedure should be general for autoionization dynamics in molecules containing light nuclei, which are ubiquitous in chemistry and biologyThis work was supported by European Research Council advanced grant 290853-XCHEM within the seventh framework program of the European Union. We also acknowledge the financial support from MINECO projects FIS2013-42002-R and FIS2016-77889-R, and the European COST (Cooperation in Science and Technology) Action XLIC CM1204, and the computer time from the Centro de Computación Científica de la Universidad Autónoma de Madrid and Marenostrum Supercomputer Center. A.P. acknowledges a Ramón y Cajal contract from the Ministerio de Economía y Competitividad (Spain). F.M. acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, grant SEV-2016-0686) and the “María de Maeztu” Programme for Units of Excellence in R&D (MDM-2014-0377). S.E.C. acknowledges funding from the Helmoltz Recognition Award. The Extreme Light Infrastructure Attosecond Light Pulse Source project (GINOP-2.3.6-15-2015-00001) was financed by the European Union and cofinanced by the European Regional Development Fun
Multiscale Modeling of Damage Processes in Aluminum Alloys: Grain-Scale Mechanisms
This paper has two goals related to the development of a physically-grounded methodology for modeling the initial stages of fatigue crack growth in an aluminum alloy. The aluminum alloy, AA 7075-T651, is susceptible to fatigue cracking that nucleates from cracked second phase iron-bearing particles. Thus, the first goal of the paper is to validate an existing framework for the prediction of the conditions under which the particles crack. The observed statistics of particle cracking (defined as incubation for this alloy) must be accurately predicted to simulate the stochastic nature of microstructurally small fatigue crack (MSFC) formation. Also, only by simulating incubation of damage in a statistically accurate manner can subsequent stages of crack growth be accurately predicted. To maintain fidelity and computational efficiency, a filtering procedure was developed to eliminate particles that were unlikely to crack. The particle filter considers the distributions of particle sizes and shapes, grain texture, and the configuration of the surrounding grains. This filter helps substantially reduce the number of particles that need to be included in the microstructural models and forms the basis of the future work on the subsequent stages of MSFC, crack nucleation and microstructurally small crack propagation. A physics-based approach to simulating fracture should ultimately begin at nanometer length scale, in which atomistic simulation is used to predict the fundamental damage mechanisms of MSFC. These mechanisms include dislocation formation and interaction, interstitial void formation, and atomic diffusion. However, atomistic simulations quickly become computationally intractable as the system size increases, especially when directly linking to the already large microstructural models. Therefore, the second goal of this paper is to propose a method that will incorporate atomistic simulation and small-scale experimental characterization into the existing multiscale framework. At the microscale, the nanoscale mechanics are represented within cohesive zones where appropriate, i.e. where the mechanics observed at the nanoscale can be represented as occurring on a plane such as at grain boundaries or slip planes at a crack front. Important advancements that are yet to be made include: 1. an increased fidelity in cohesive zone modeling; 2. a means to understand how atomistic simulation scales with time; 3. a new experimental methodology for generating empirical models for CZMs and emerging materials; and 4. a validation of simulations of the damage processes at the nano-micro scale. With ever-increasing computer power, the long-term ability to employ atomistic simulation for the prognosis of structural components will not be limited by computation power, but by our lack of knowledge in incorporating atomistic models into simulations of MSFC into a multiscale framework
CMS ridge effect at LHC as a manifestation of bremstralung of gluons due to the quark-anti-quark string formation
The recently reported effect of long-range near-side angular correlations at
LHC occurs for large multiplicities of particles with
. To understand the effect several possibilities have
been discussed. In the letter we propose a simple qualitative mechanism which
corresponds to gluon bremstralung of quarks moving with acceleration
appropriate to the quark--anti-quark string. The smallness of azimuthal angle
difference along with large at large multiplicities
in this interval of are natural in the mechanism. The mechanism predicts
also bremstralung photons with mean values of and
.Comment: 5 pages, 3 figure
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