2,299 research outputs found
The Labor Market, Then and Now: Changing Realities in the 21st Century
Skyrocketing unemployment is only one of a number of profound changes transforming the U.S. labor market, workforce, and education system in the first decade of the 21st Century. The new realities affecting jobs, careers, and retirement are transforming Americans' attitudes toward work. This research brief, capturing the changing perceptions of workers between 1999 and 2009, was prepared by Carl Van Horn and Nicole Corre of the John J. Heldrich Center for Workforce Development, a research and policy center at Rutgers University. The brief summarizes workforce mega-trends by drawing upon the most authoritative sources available and from the Heldrich Center's Work Trends series of two-dozen nationwide worker surveys that began in 1998. (The complete set of Work Trends surveys is available at www.heldrich.rutgers.edu)
Composition of Jupiter irregular satellites sheds light on their origin
Irregular satellites of Jupiter with their highly eccentric, inclined and
distant orbits suggest that their capture took place just before the giant
planet migration. We aim to improve our understanding of the surface
composition of irregular satellites of Jupiter to gain insight into a narrow
time window when our Solar System was forming. We observed three Jovian
irregular satellites, Himalia, Elara, and Carme, using a medium-resolution
0.8-5.5 micro m spectrograph on the National Aeronautics and Space
Administration (NASA) Infrared Telescope Facility (IRTF). Using a linear
spectral unmixing model we have constrained the major mineral phases on the
surface of these three bodies. Our results confirm that the surface of Himalia,
Elara, and Carme are dominated by opaque materials such as those seen in
carbonaceous chondrite meteorites. Our spectral modeling of NIR spectra of
Himalia and Elara confirm that their surface composition is the same and
magnetite is the dominant mineral. A comparison of the spectral shape of
Himalia with the two large main C-type asteroids, Themis (D 176 km) and Europa
(D 352 km), suggests surface composition similar to Europa. The NIR spectrum of
Carme exhibits blue slope up to 1.5 microm and is spectrally distinct from
those of Himalia and Elara. Our model suggests that it is compositionally
similar to amorphous carbon. Himalia and Elara are compositionally similar but
differ significantly from Carme. These results support the hypotheses that the
Jupiter irregular satellites are captured bodies that were subject to further
breakup events and clustered as families based on their similar physical and
surface compositions
Coupled swelling and large strain model for hydrogels: application to the nucleus pulposus of the intervertebral disc
The main constituents of the nucleus puposus , the centrl gelatinous part of the intervertebral disc, are water and a solid extracellular matrix of macromolecules. Based on this observation, the nucleus pulposus can be seen as a gel-like material in wich swelling - due to the diffusion of the fluid molecules into the macromolecular network - and large strain elasticity, induced by the macromollecular chains, occur. In recent literature, many autors have been interested in describing such a coupled deformation-diffusion problem for gels. Most of the tim, these works where formulated with respect to the dry configuration of the material. Howevver, for the nucleus pulposus, the dru configuration does not exist. Thus, the formulation of the deformation-diffusion problem should be modified in order to consider a reference configuration, wich is undeformed and unconstrained (but already swollen).
The theoretical aspects of the derivation of this coupled deformation-diffusion model is proposed. Then, this model is numerically implemented in the finite element commercial software ABAQUS. The state of equilibrium are investigated on simple homogeneous examples. Finally, the himan nucleus pulposus of the intervertebral disc is chosen as a representative complex crample of application for this approach. The associated annulus fibrosus is modelled using an anisotropic hyperelastic material law
Olivine or Impact Melt: Nature of the "Orange" Material on Vesta from Dawn
NASA's Dawn mission observed a great variety of colored terrains on asteroid
(4) Vesta during its survey with the Framing Camera (FC). Here we present a
detailed study of the orange material on Vesta, which was first observed in
color ratio images obtained by the FC and presents a red spectral slope. The
orange material deposits can be classified into three types, a) diffuse ejecta
deposited by recent medium-size impact craters (such as Oppia), b) lobate
patches with well-defined edges, and c) ejecta rays from fresh-looking impact
craters. The location of the orange diffuse ejecta from Oppia corresponds to
the olivine spot nicknamed "Leslie feature" first identified by Gaffey (1997)
from ground-based spectral observations. The distribution of the orange
material in the FC mosaic is concentrated on the equatorial region and almost
exclusively outside the Rheasilvia basin. Our in-depth analysis of the
composition of this material uses complementary observations from FC, the
visible and infrared spectrometer (VIR), and the Gamma Ray and Neutron Detector
(GRaND). Combining the interpretations from the topography, geomorphology,
color and spectral parameters, and elemental abundances, the most probable
analog for the orange material on Vesta is impact melt
Modeling the architecture of the regulatory system controlling methylenomycin production in Streptomyces coelicolor
The antibiotic methylenomycin A is produced naturally by Streptomyces coelicolor A3(2), a model organism for streptomycetes. This compound is of particular interest to synthetic biologists because all of the associated biosynthetic, regulatory and resistance genes are located on a single cluster on the SCP1 plasmid, making the entire module easily transferable between different bacterial strains. Understanding further the regulation and biosynthesis of the methylenomycin producing gene cluster could assist in the identification of motifs that can be exploited in synthetic regulatory systems for the rational engineering of novel natural products and antibiotics
Contraintes mémoire et solution architecturale pour applications TDSI
- Les systèmes supportant des applications de traitement du signal et de l'image manipulent de plus en plus de données. Cela entraîne une utilisation intensive de la mémoire qui devient le point critique du système ; la mémoire limite les performances et représente une proportion importante de la consommation globale. Dans le cadre du projet RNRT ALIPTA nous développons l'outil de synthèse d'architecture GAUT en nous intéressant à la synthèse de la partie mémoire. Nous évaluerons l'impact de contraintes de mémorisation sur les architectures pour différentes applications en traitement du signal et de l'image
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