574 research outputs found
High-order harmonic generation driven by chirped laser pulses induced by linear and non linear phenomena
We present a theoretical study of high-order harmonic generation (HHG) driven
by ultrashort optical pulses with different kind of chirps. The goal of the
present work is perform a detailed study to clarify the relevant parameters in
the chirped pulses to achieve a noticeable cut-off extensions in HHG. These
chirped pulses are generated using both linear and nonlinear dispersive
media.The description of the origin of the physical mechanisms responsible of
this extension is, however, not usually reported with enough detail in the
literature. The study of the behaviour of the harmonic cut-off with these kind
of pulses is carried out in the classical context, by the integration of the
Newton-Lorentz equation complemented with the quantum approach, based on the
integration of the time dependent Schr\"odinger equation in full dimensions
(TDSE-3D), we are able to understand the underlying physics.Comment: 13 pages, 8 figure
Isotopic equilibria in aqueous clusters at low temperatures: Insights from the MB-pol many-body potential
By combining path-integrals molecular dynamics simulations with the accurate MB-pol potential energy surface, we investigate the role of alternative potential models on isotopic fractionation ratios between H and D atoms at dangling positions in water clusters at low temperatures. Our results show clear stabilizations of the lighter isotope at dangling sites, characterized by free energy differences ΔG that become comparable to or larger than kBT for temperatures below ∼75 K. The comparison between these results to those previously reported using the empirical q-TIP4P/F water model [P. E. Videla et al., J. Phys. Chem. Lett. 5, 2375 (2014)] reveals that the latter Hamiltonian overestimates the H stabilization by ∼25%. Moreover, predictions from the MB-pol model are in much better agreement with measured results reported for similar isotope equilibria at ice surfaces. The dissection of the quantum kinetic energies into orthogonal directions shows that the dominant differences between the two models are to be found in the anharmonic characteristics of the potential energy surfaces along OH bond directions involved in hydrogen bonds.Fil: Videla, Pablo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rossky, Peter J.. Rice University; Estados UnidosFil: Laria, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Comisión Nacional de Energía Atómica; Argentin
Human embryonic stem cells and derived contractile embryoid bodies are susceptible to Coxsakievirus B infection and respond to interferon Iβ treatment
AbstractWe studied the susceptibility of human embryonic stem cells and derived contractile embryoid bodies from WAO9, HUES-5 and HUES-16 cell lines to Coxsackievirus B infection. After validating stem cell-like properties and cardiac phenotype, Coxsackievirus B receptors CAR and DAF, as well as type I interferon receptors were detected in all cell lines and differentiation stages studied. Real-time PCR analysis showed that CAR mRNA levels were 3.4-fold higher in undifferentiated cells, while DAF transcript levels were 2.78-fold more abundant in differentiated cultures (P<0.05). All cell lines were susceptible to Coxsackievirus serotypes B1-5 infection as shown by RT-PCR detection of viral RNA, immunofluorescence detection of viral protein and infectivity titration of cell culture supernatants resulting in cell death. Supernatants infectivity titers 24-48h post-infection ranged from 105-106 plaque forming units (PFU)/ml, the highest titers were detected in undifferentiated cells. Cell viability detected by a colorimetric assay, showed inverse correlation with infectivity titers of cell culture supernatants. Treatment with 100 U of interferon Iβ significantly reduced viral replication and associated cell death during a 24–48 h observation period, as detected by reduced infectivity titers in the supernatants and increased cell viability by a colorimetric assay, respectively. We propose human embryonic stem cell and derived contractile embryoid bodies as a valid model to study cardiac Coxsackievirus B infection
ALMA Long Baseline Observations of the Strongly Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z=3.042
We present initial results of very high resolution Atacama Large
Millimeter/submillimeter Array (ALMA) observations of the =3.042
gravitationally lensed galaxy HATLAS J090311.6+003906 (SDP.81). These
observations were carried out using a very extended configuration as part of
Science Verification for the 2014 ALMA Long Baseline Campaign, with baselines
of up to 15 km. We present continuum imaging at 151, 236 and 290 GHz, at
unprecedented angular resolutions as fine as 23 milliarcseconds (mas),
corresponding to an un-magnified spatial scale of ~180 pc at z=3.042. The ALMA
images clearly show two main gravitational arc components of an Einstein ring,
with emission tracing a radius of ~1.5". We also present imaging of CO(10-9),
CO(8-7), CO(5-4) and H2O line emission. The CO emission, at an angular
resolution of ~170 mas, is found to broadly trace the gravitational arc
structures but with differing morphologies between the CO transitions and
compared to the dust continuum. Our detection of H2O line emission, using only
the shortest baselines, provides the most resolved detection to date of thermal
H2O emission in an extragalactic source. The ALMA continuum and spectral line
fluxes are consistent with previous Plateau de Bure Interferometer and
Submillimeter Array observations despite the impressive increase in angular
resolution. Finally, we detect weak unresolved continuum emission from a
position that is spatially coincident with the center of the lens, with a
spectral index that is consistent with emission from the core of the foreground
lensing galaxy.Comment: 9 pages, 5 figures and 3 tables, accepted for publication in the
Astrophysical Journal Letter
ALMA Observations of Asteroid 3 Juno at 60 Kilometer Resolution
We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm
continuum images of the asteroid 3 Juno obtained with an angular resolution of
0.042 arcseconds (60 km at 1.97 AU). The data were obtained over a single 4.4
hr interval, which covers 60% of the 7.2 hr rotation period, approximately
centered on local transit. A sequence of ten consecutive images reveals
continuous changes in the asteroid's profile and apparent shape, in good
agreement with the sky projection of the three-dimensional model of the
Database of Asteroid Models from Inversion Techniques. We measure a geometric
mean diameter of 259pm4 km, in good agreement with past estimates from a
variety of techniques and wavelengths. Due to the viewing angle and inclination
of the rotational pole, the southern hemisphere dominates all of the images.
The median peak brightness temperature is 215pm13 K, while the median over the
whole surface is 197pm15 K. With the unprecedented resolution of ALMA, we find
that the brightness temperature varies across the surface with higher values
correlated to the subsolar point and afternoon areas, and lower values beyond
the evening terminator. The dominance of the subsolar point is accentuated in
the final four images, suggesting a reduction in the thermal inertia of the
regolith at the corresponding longitudes, which are possibly correlated to the
location of the putative large impact crater. These results demonstrate ALMA's
potential to resolve thermal emission from the surface of main belt asteroids,
and to measure accurately their position, geometric shape, rotational period,
and soil characteristics.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in the
Astrophysical Journal Letter
Sustainable Pavement Management. Integrating Economic, Technical, and Environmental Aspects in Decision Making
Sustainability, which is founded in the reconciliation of economic, environmental and social aspects, has become a major issue for infrastructure managers. The economic and environmental impacts of pavement maintenance are not negligible. More than 400 billion USD are invested globally each year in pavement construction and maintenance. These tasks increase the environmental impacts of vehicle operation by 10%. Because maintenance should be technically appropriate, it is important to integrate technical, economic and environmental aspects in the evaluation of maintenance alternatives over the life cycle of pavement. However, these aspects are normally assessed in different units that are difficult to combine in the decision-making process.
This research examines and compares different methods for the integrated consideration of technical, economic and environmental aspects. This study aims to assist highway agencies, researchers and practitioners with the integration of these aspects for the sustainable management of pavement. For this purpose, a set of maintenance alternatives for asphalt pavements are evaluated. Different methods for the integration of these aspects are explored, leading to recommendations for the most suitable methods for different scenarios. Because of this analysis, the Analytic Hierarchy Process (AHP) is recommended when the number of alternatives is reduced. In these situations, the AHP leads to results that are similar to those of the Weighting Sum and Multi-Attribute approaches that are frequently used for intuitive selection. However, when the number of alternatives is large, pair comparison becomes difficult when using the AHP and the Weighting Sum method becomes more appropriate.The authors gratefully acknowledge the scholarship awarded by the Vicerrectoria de Investigacion from the Pontificia Universidad Catolica de Chile and funded by the Ministerio de Educacion de Chile. The research team acknowledges FONDEF-Comision Nacional de Investigacion Cientifica y Technologica (CONICYT) 2009 for funding the project Research and Development of Solutions for Urban Pavement Management in Chile. In addition, the authors sincerely appreciate the funding provided by CONICYT and the National Research Center for Integrated Natural Disaster Management.Torres Machí, C.; Chamorro, A.; Pellicer Armiñana, E.; Yepes, V.; Videla, C. (2015). Sustainable Pavement Management. Integrating Economic, Technical, and Environmental Aspects in Decision Making. Transportation Research Record. 2523:56-63. doi:10.3141/2523-07S56632523Chester, M. V., & Horvath, A. (2009). Environmental assessment of passenger transportation should include infrastructure and supply chains. Environmental Research Letters, 4(2), 024008. doi:10.1088/1748-9326/4/2/024008Chamorro, A., & Tighe, S. L. (2009). Development of a Management Framework for Rural Roads in Developing Countries. Transportation Research Record: Journal of the Transportation Research Board, 2093(1), 99-107. doi:10.3141/2093-12Torres-Machi, C., Chamorro, A., Yepes, V., & Pellicer, E. (2014). Current models and practices of economic and environmental evaluation for sustainable network-level pavement management. Revista de la construcción, 13(2), 49-56. doi:10.4067/s0718-915x2014000200006Haas, R., Tighe, S. L., & Falls, L. C. (2006). Determining Return on Long-Life Pavement Investments. Transportation Research Record: Journal of the Transportation Research Board, 1974(1), 10-17. doi:10.1177/0361198106197400102Wu, Z., Flintsch, G., Ferreira, A., & Picado-Santos, L. de. (2012). Framework for Multiobjective Optimization of Physical Highway Assets Investments. Journal of Transportation Engineering, 138(12), 1411-1421. doi:10.1061/(asce)te.1943-5436.0000458Wu, Z., & Flintsch, G. W. (2009). Pavement Preservation Optimization Considering Multiple Objectives and Budget Variability. Journal of Transportation Engineering, 135(5), 305-315. doi:10.1061/(asce)te.1943-5436.0000006Cafiso, S., Di Graziano, A., Kerali, H. R., & Odoki, J. B. (2002). Multicriteria Analysis Method for Pavement Maintenance Management. Transportation Research Record: Journal of the Transportation Research Board, 1816(1), 73-84. doi:10.3141/1816-09Giustozzi, F., Crispino, M., & Flintsch, G. (2012). Multi-attribute life cycle assessment of preventive maintenance treatments on road pavements for achieving environmental sustainability. The International Journal of Life Cycle Assessment, 17(4), 409-419. doi:10.1007/s11367-011-0375-6Nathman, R., McNeil, S., & Van Dam, T. J. (2009). Integrating Environmental Perspectives into Pavement Management. Transportation Research Record: Journal of the Transportation Research Board, 2093(1), 40-49. doi:10.3141/2093-05Robinette, C., & Epps, J. (2010). Energy, Emissions, Material Conservation, and Prices Associated with Construction, Rehabilitation, and Material Alternatives for Flexible Pavement. Transportation Research Record: Journal of the Transportation Research Board, 2179(1), 10-22. doi:10.3141/2179-02Osorio, A., Chamorro, A., Tighe, S., & Videla, C. (2014). Calibration and Validation of Condition Indicator for Managing Urban Pavement Networks. Transportation Research Record: Journal of the Transportation Research Board, 2455(1), 28-36. doi:10.3141/2455-04Saaty, T. L. (1990). How to make a decision: The analytic hierarchy process. European Journal of Operational Research, 48(1), 9-26. doi:10.1016/0377-2217(90)90057-
First Results from High Angular Resolution ALMA Observations Toward the HL Tau Region
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
from the 2014 Long Baseline Campaign in dust continuum and spectral line
emission from the HL Tau region. The continuum images at wavelengths of 2.9,
1.3, and 0.87 mm have unprecedented angular resolutions of 0.075 arcseconds (10
AU) to 0.025 arcseconds (3.5 AU), revealing an astonishing level of detail in
the circumstellar disk surrounding the young solar analogue HL Tau, with a
pattern of bright and dark rings observed at all wavelengths. By fitting
ellipses to the most distinct rings, we measure precise values for the disk
inclination (46.72pm0.05 degrees) and position angle (+138.02pm0.07 degrees).
We obtain a high-fidelity image of the 1.0 mm spectral index (), which
ranges from in the optically-thick central peak and two
brightest rings, increasing to 2.3-3.0 in the dark rings. The dark rings are
not devoid of emission, we estimate a grain emissivity index of 0.8 for the
innermost dark ring and lower for subsequent dark rings, consistent with some
degree of grain growth and evolution. Additional clues that the rings arise
from planet formation include an increase in their central offsets with radius
and the presence of numerous orbital resonances. At a resolution of 35 AU, we
resolve the molecular component of the disk in HCO+ (1-0) which exhibits a
pattern over LSR velocities from 2-12 km/s consistent with Keplerian motion
around a ~1.3 solar mass star, although complicated by absorption at low
blue-shifted velocities. We also serendipitously detect and resolve the nearby
protostars XZ Tau (A/B) and LkHa358 at 2.9 mm.Comment: 11 pages, 5 figures, 2 tables, accepted for publication in the
Astrophysical Journal Letter
The selective phosphodiesterase 4 inhibitor roflumilast and phosphodiesterase 3/4 inhibitor pumafentrine reduce clinical score and TNF expression in experimental colitis in mice.
The specific inhibition of phosphodiesterase (PDE)4 and dual inhibition of PDE3 and PDE4 has been shown to decrease inflammation by suppression of pro-inflammatory cytokine synthesis. We examined the effect of roflumilast, a selective PDE4 inhibitor marketed for severe COPD, and the investigational compound pumafentrine, a dual PDE3/PDE4 inhibitor, in the preventive dextran sodium sulfate (DSS)-induced colitis model. The clinical score, colon length, histologic score and colon cytokine production from mice with DSS-induced colitis (3.5% DSS in drinking water for 11 days) receiving either roflumilast (1 or 5 mg/kg body weight/d p.o.) or pumafentrine (1.5 or 5 mg/kg/d p.o.) were determined and compared to vehicle treated control mice. In the pumafentrine-treated animals, splenocytes were analyzed for interferon-γ (IFNγ) production and CD69 expression. Roflumilast treatment resulted in dose-dependent improvements of clinical score (weight loss, stool consistency and bleeding), colon length, and local tumor necrosis factor-α (TNFα) production in the colonic tissue. These findings, however, were not associated with an improvement of the histologic score. Administration of pumafentrine at 5 mg/kg/d alleviated the clinical score, the colon length shortening, and local TNFα production. In vitro stimulated splenocytes after in vivo treatment with pumafentrine showed a significantly lower state of activation and production of IFNγ compared to no treatment in vivo. These series of experiments document the ameliorating effect of roflumilast and pumafentrine on the clinical score and TNF expression of experimental colitis in mice
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