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The effects of high strain-rate and in-plane restraint on quasi-statically loaded laminated glass: a theoretical study with applications to blast enhancement
Abstract: Laminated glass panels are increasingly used to improve the blast resilience of glazed facades, as part of efforts to mitigate the threat posed to buildings and their occupants by terrorist attacks. The blast response of these ductile panels is still only partially understood, with an evident knowledge gap between fundamental behaviour at the material level and observations from full-scale blast tests. To enhance our understanding, and help bridge this gap, this paper adopts a ‘first principles’ approach to investigate the effects of high strain-rate, associated with blast loading, and the in-plane restraint offered by blast-resistant frames. These are studied by developing simplified analytical beam models, for all stages of deformation, that account for the enhanced properties of both the glass and the interlayer at high strain-rates. The increased shear modulus of the interlayer results in a composite bending response of the un-fractured laminated glass. This also enhances the residual post-fracture bending moment capacity, arising from the combined action of the glass fragments in compression and the interlayer in tension, which is considered negligible under low strain-rates. The post-fracture resistance is significantly improved by the introduction of in-plane restraint, due to the membrane action associated with panel stretching under large deflections. This is demonstrated by developing a yield condition that accounts for the relative contributions of bending and membrane action, and applying the upper bound theorem of plasticity, assuming a tearing failure of the interlayer. Future work aims to complete the theoretical framework by including the assessment of plate-action and inertia effects
Inelastic electron tunneling via molecular vibrations in single-molecule transistors
In single-molecule transistors, we observe inelastic cotunneling features
that correspond energetically to vibrational excitations of the molecule, as
determined by Raman and infrared spectroscopy. This is a form of inelastic
electron tunneling spectroscopy of single molecules, with the transistor
geometry allowing in-situ tuning of the electronic states via a gate electrode.
The vibrational features shift and change shape as the electronic levels are
tuned near resonance, indicating significant modification of the vibrational
states. When the molecule contains an unpaired electron, we also observe
vibrational satellite features around the Kondo resonance.Comment: 5 pages, 4 figures. Supplementary information available upon reques
Infrared study of spin crossover Fe-picolylamine complex
Infrared (IR) absorption spectroscopy has been used to probe the evolution of
microscopic vibrational states upon the temperature- and photo-induced spin
crossovers in [Fe(2-picolylamine)3]Cl2EtOH (Fe-pic). To overcome the small
sizes and the strong IR absorption of the crystal samples used, an IR
synchrotron radiation source and an IR microscope have been used. The obtained
IR spectra of Fe-pic show large changes between high-spin and low-spin states
for both the temperature- and the photo- induced spin crossovers. Although the
spectra in the temperature- and photo-induced high-spin states are relatively
similar to each other, they show distinct differences below 750 cm-1. This
demonstrates that the photo-induced high-spin state involves microscopically
different characters from those of the temperature-induced high-spin state. The
results are discussed in terms of local pressure and structural deformations
within the picolylamine ligands, and in terms of their possible relevance to
the development of macroscopic photo-induced phase in Fe-pic.Comment: 6 pages (text) and 6 figures,submitted to J. Phys. Soc. Jp
Upper Limits to Fluxes of Neutrinos and Gamma-Rays from Starburst Galaxies
Loeb and Waxman have argued that high energy neutrinos from the decay of
pions produced in interactions of cosmic rays with interstellar gas in
starburst galaxies would be produced with a large enough flux to be observable.
Here we obtain an upper limit to the diffuse neutrino flux from starburst
galaxies which is a factor of 5 lower than the flux which they predict.
Compared with predicted fluxes from other extragalactic high energy neutrino
sources, starburst neutrinos with PeV energies would have a flux
considerably below that predicted for AGN models. We also estimate an upper
limit for the diffuse GeV -ray flux from starbust galaxies to be
of the observed -ray background, much less than
the component from unresolved blazars.Comment: 4 pages, for Proc. TeV2 Conf., Madison, WI, to be published in J.
Phy
The Persistence of Cool Galactic Winds in High Stellar Mass Galaxies Between z~1.4 and ~1
We present an analysis of the MgII 2796, 2803 and FeII 2586, 2600 absorption
line profiles in coadded spectra of 468 galaxies at 0.7 < z < 1.5. The galaxy
sample, drawn from the Team Keck Treasury Redshift Survey of the GOODS-N field,
has a range in stellar mass (M_*) comparable to that of the sample at z~1.4
analyzed in a similar manner by Weiner et al. (2009; W09), but extends to lower
redshifts and has specific star formation rates which are lower by ~0.6 dex. We
identify outflows of cool gas from the Doppler shift of the MgII absorption
lines and find that the equivalent width (EW) of absorption due to outflowing
gas increases on average with M_* and star formation rate (SFR). We attribute
the large EWs measured in spectra of the more massive, higher-SFR galaxies to
optically thick absorbing clouds having large velocity widths. The outflows
have hydrogen column densities N(H) > 10^19.3 cm^-2, and extend to velocities
of ~500 km/s. While galaxies with SFR > 10 Msun/yr host strong outflows in both
this and the W09 sample, we do not detect outflows in lower-SFR (i.e., log
M_*/Msun < 10.5) galaxies at lower redshifts. Using a simple galaxy evolution
model which assumes exponentially declining SFRs, we infer that strong outflows
persist in galaxies with log M_*/Msun > 10.5 as they age between z=1.4 and z~1,
presumably because of their high absolute SFRs. Finally, using high resolution
HST/ACS imaging in tandem with our spectral analysis, we find evidence for a
weak trend (at 1 sigma significance) of increasing outflow absorption strength
with increasing galaxy SFR surface density.Comment: Submitted to ApJ. 25 pages, 19 figures, Figure 2 reduced in
resolution. Uses emulateapj forma
Local Radiative Hydrodynamic and Magnetohydrodynamic Instabilities in Optically Thick Media
We examine the local conditions for radiative damping and driving of short
wavelength, propagating hydrodynamic and magnetohydrodynamic (MHD) waves in
static, optically thick, stratified equilibria. We show that so-called strange
modes in stellar oscillation theory and magnetic photon bubbles are intimately
related and are both fundamentally driven by the background radiation flux
acting on compressible waves. We identify the necessary criteria for unstable
driving of these waves, and show that this driving can exist in both gas and
radiation pressure dominated media, as well as pure Thomson scattering media in
the MHD case. The equilibrium flux acting on opacity fluctuations can drive
both hydrodynamic acoustic waves and magnetosonic waves unstable. In addition,
magnetosonic waves can be driven unstable by a combination of the equilibrium
flux acting on density fluctuations and changes in the background radiation
pressure along fluid displacements. We briefly describe the conditions under
which these instabilities might be manifested in both main sequence stellar
envelopes and accretion disks.Comment: 55 pages, revised version accepted for publication by ApJ. New
appendix added justifying WKB analysi
Plasmodium vivax circumsporozoite genotypes: a limited variation or new subspecies with major biological consequences?
<p>Abstract</p> <p>Background</p> <p><it>Plasmodium vivax </it>circumsporozoite variants have been identified in several geographical areas. The real implication of the genetic variation in this region of the <it>P. vivax </it>genome has been questioned for a long time. Although previous studies have observed significant association between VK210 and the Duffy blood group, we present here that evidences of this variation are limited to the CSP central portion.</p> <p>Methods</p> <p>The phylogenetic analyses were accomplished starting from the amplification of conserved domains of <it>18 SSU RNAr </it>and <it>Cyt B</it>. The antibodies responses against the CSP peptides, MSP-1, AMA-1 and DBP were detected by ELISA, in plasma samples of individuals infected with two <it>P. vivax CS </it>genotypes: VK210 and <it>P. vivax</it>-like.</p> <p>Results</p> <p>These analyses of the two markers demonstrate high similarity among the <it>P. vivax CS </it>genotypes and surprisingly showed diversity equal to zero between VK210 and <it>P. vivax</it>-like, positioning these <it>CS </it>genotypes in the same clade. A high frequency IgG antibody against the N- and C-terminal regions of the <it>P. vivax </it>CSP was found as compared to the immune response to the R- and V- repetitive regions (<it>p </it>= 0.0005, Fisher's Exact test). This difference was more pronounced when the <it>P. vivax</it>-like variant was present in the infection (<it>p </it>= 0.003, Fisher's Exact test). A high frequency of antibody response against MSP-1 and AMA-1 peptides was observed for all <it>P. vivax CS </it>genotypes in comparison to the same frequency for DBP.</p> <p>Conclusions</p> <p>This results target that the differences among the <it>P. vivax CS </it>variants are restrict to the central repeated region of the protein, mostly nucleotide variation with important serological consequences.</p
Immunogenicity of a Prime-Boost Vaccine Containing the Circumsporozoite Proteins of Plasmodium vivax in Rodents
Plasmodium vivax is the most widespread and the second most prevalent malaria-causing species in the world. Current measures used to control the transmission of this disease would benefit from the development of an efficacious vaccine. in the case of the deadly parasite P. falciparum, the recombinant RTS,S vaccine containing the circumsporozoite antigen (CSP) consistently protects 30 to 50% of human volunteers against infection and is undergoing phase III clinical trials in Africa with similar efficacy. These findings encouraged us to develop a P. vivax vaccine containing the three circulating allelic forms of P. vivax CSP. Toward this goal, we generated three recombinant bacterial proteins representing the CSP alleles, as well as a hybrid polypeptide called PvCSP-All-CSP-epitopes. This hybrid contains the conserved N and C termini of P. vivax CSP and the three variant repeat domains in tandem. We also generated simian and human recombinant replication-defective adenovirus vectors expressing PvCSP-All-CSP-epitopes. Mice immunized with the mixture of recombinant proteins in a formulation containing the adjuvant poly(I.C) developed high and long-lasting serum IgG titers comparable to those elicited by proteins emulsified in complete Freund's adjuvant. Antibody titers were similar in mice immunized with homologous (protein-protein) and heterologous (adenovirus- protein) vaccine regimens. the antibodies recognized the three allelic forms of CSP, reacted to the repeated and nonrepeated regions of CSP, and recognized sporozoites expressing the alleles VK210 and VK247. the vaccine formulations described in this work should be useful for the further development of an anti-P. vivax vaccine.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)PNPDCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Escola Paulista Med, Ctr Terapia Celular & Mol CTCMol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilWistar Inst Anat & Biol, Philadelphia, PA 19104 USAMalaria Vaccine & Drug Dev Ctr, Cali, ColombiaUniv Fed Santa Catarina, Dept Microbiol Imunol & Parasitol, Florianopolis, SC, BrazilUniv São Paulo, Fac Ciencias Farmaceut, Dept Anal Clin & Toxicol, São Paulo, BrazilNYU, Sch Med, Dept Pathol, Michael Heidelberger Div, New York, NY USAUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Terapia Celular & Mol CTCMol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilFAPESP: 2009/15432-4FAPESP: 2012/13032-5CNPq: 471087/2013-0Web of Scienc
Galactic winds driven by cosmic-ray streaming
Galactic winds are observed in many spiral galaxies with sizes from dwarfs up
to the Milky Way, and they sometimes carry a mass in excess of that of newly
formed stars by up to a factor of ten. Multiple driving processes of such winds
have been proposed, including thermal pressure due to supernova-heating, UV
radiation pressure on dust grains, or cosmic ray (CR) pressure. We here study
wind formation due to CR physics using a numerical model that accounts for CR
acceleration by supernovae, CR thermalization, and advective CR transport. In
addition, we introduce a novel implementation of CR streaming relative to the
rest frame of the gas. We find that CR streaming drives powerful and sustained
winds in galaxies with virial masses M_200 < 10^{11} Msun. In dwarf galaxies
(M_200 ~ 10^9 Msun) the winds reach a mass loading factor of ~5, expel ~60 per
cent of the initial baryonic mass contained inside the halo's virial radius and
suppress the star formation rate by a factor of ~5. In dwarfs, the winds are
spherically symmetric while in larger galaxies the outflows transition to
bi-conical morphologies that are aligned with the disc's angular momentum axis.
We show that damping of Alfven waves excited by streaming CRs provides a means
of heating the outflows to temperatures that scale with the square of the
escape speed. In larger haloes (M_200 > 10^{11} Msun), CR streaming is able to
drive fountain flows that excite turbulence. For halo masses M_200 > 10^{10}
Msun, we predict an observable level of H-alpha and X-ray emission from the
heated halo gas. We conclude that CR-driven winds should be crucial in
suppressing and regulating the first epoch of galaxy formation, expelling a
large fraction of baryons, and - by extension - aid in shaping the faint end of
the galaxy luminosity function. They should then also be responsible for much
of the metal enrichment of the intergalactic medium.Comment: 25 pages, 14 figures, accepted by MNRA
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