1,726 research outputs found
Virtual Epistemologies for the Producer-Consumer Problem
In recent years, much research has been de- voted to the construction of the lookaside buffer that made emulating and possibly eval- uating suffix trees a reality; however, few have synthesized the investigation of RPCs. Given the current status of random theory, futurists daringly desire the improvement of voice-over-IP that would allow for further study into telephony, demonstrates the ap- propriate importance of cryptography. In this paper, we propose a read-write tool for analyzing scatter/gather I/O (Yerba), which we use to confirm that hierarchical databases and multi-processors can connect to accomplish this goal
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Deducing signaling pathways from parallel actions of arsenite and antimonite in human epidermal keratinocytes.
Inorganic arsenic oxides have been identified as carcinogens in several human tissues, including epidermis. Due to the chemical similarity between trivalent inorganic arsenic (arsenite) and antimony (antimonite), we hypothesized that common intracellular targets lead to similarities in cellular responses. Indeed, transcriptional and proteomic profiling revealed remarkable similarities in differentially expressed genes and proteins resulting from exposure of cultured human epidermal keratinocytes to arsenite and antimonite in contrast to comparisons of arsenite with other metal compounds. These data were analyzed to predict upstream regulators and affected signaling pathways following arsenite and antimonite treatments. A majority of the top findings in each category were identical after treatment with either compound. Inspection of the predicted upstream regulators led to previously unsuspected roles for oncostatin M, corticosteroids and ephrins in mediating cellular response. The influence of these predicted mediators was then experimentally verified. Together with predictions of transcription factor effects more generally, the analysis has led to model signaling networks largely accounting for arsenite and antimonite action. The striking parallels between responses to arsenite and antimonite indicate the skin carcinogenic risk of exposure to antimonite merits close scrutiny
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Revealing nascent proteomics in signaling pathways and cell differentiation.
Regulation of gene expression at the level of protein synthesis is a crucial element in driving how the genetic landscape is expressed. However, we are still limited in technologies that can quantitatively capture the immediate proteomic changes that allow cells to respond to specific stimuli. Here, we present a method to capture and identify nascent proteomes in situ across different cell types without disturbing normal growth conditions, using O-propargyl-puromycin (OPP). Cell-permeable OPP rapidly labels nascent elongating polypeptides, which are subsequently conjugated to biotin-azide, using click chemistry, and captured with streptavidin beads, followed by digestion and analysis, using liquid chromatography-tandem mass spectrometry. Our technique of OPP-mediated identification (OPP-ID) allows detection of widespread proteomic changes within a short 2-hour pulse of OPP. We illustrate our technique by recapitulating alterations of proteomic networks induced by a potent mammalian target of rapamycin inhibitor, MLN128. In addition, by employing OPP-ID, we identify more than 2,100 proteins and uncover distinct protein networks underlying early erythroid progenitor and differentiation states not amenable to alternative approaches such as amino acid analog labeling. We present OPP-ID as a method to quantitatively identify nascent proteomes across an array of biological contexts while preserving the subtleties directing signaling in the native cellular environment
Fixing the U-band photometry of Type Ia supernovae
We present previously unpublished photometry of supernovae 2003gs and 2003hv.
Using spectroscopically-derived corrections to the U-band photometry, we
reconcile U-band light curves made from imagery with the Cerro Tololo 0.9-m,
1.3-m and Las Campanas 1-m telescopes. Previously, such light curves showed a
0.4 mag spread at one month after maximum light. This gives us hope that a set
of corrected ultraviolet light curves of nearby objects can contribute to the
full utilization of rest frame U-band data of supernovae at redshift ~0.3 to
0.8. As pointed out recently by Kessler et al. in the context of the Sloan
Digital Sky Survey supernova search, if we take the published U-band photometry
of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly
in the distance moduli of higher redshift objects. This anomaly led the Sloan
survey to eliminate from their analyses all photometry obtained in the rest
frame U-band. The Supernova Legacy Survey eliminated observer frame U-band
photometry, which is to say nearby objects observed in the U-band, but they
used photometry of high redshift objects no matter in which band the photons
were emitted.Comment: 25 pages, 9 figures, accepted for publication in the Astronomical
Journa
An Exactly Solvable Phase-Field Theory of Dislocation Dynamics, Strain Hardening and Hysteresis in Ductile Single Crystals
An exactly solvable phase-field theory of dislocation dynamics, strain
hardening and hysteresis in ductile single crystals is developed. The theory
accounts for: an arbitrary number and arrangement of dislocation lines over a
slip plane; the long-range elastic interactions between dislocation lines; the
core structure of the dislocations resulting from a piecewise quadratic Peierls
potential; the interaction between the dislocations and an applied resolved
shear stress field; and the irreversible interactions with short-range
obstacles and lattice friction, resulting in hardening, path dependency and
hysteresis. A chief advantage of the present theory is that it is analytically
tractable, in the sense that the complexity of the calculations may be reduced,
with the aid of closed form analytical solutions, to the determination of the
value of the phase field at point-obstacle sites. In particular, no numerical
grid is required in calculations. The phase-field representation enables
complex geometrical and topological transitions in the dislocation ensemble,
including dislocation loop nucleation, bow-out, pinching, and the formation of
Orowan loops. The theory also permits the consideration of obstacles of varying
strengths and dislocation line-energy anisotropy. The theory predicts a range
of behaviors which are in qualitative agreement with observation, including:
hardening and dislocation multiplication in single slip under monotonic
loading; the Bauschinger effect under reverse loading; the fading memory
effect, whereby reverse yielding gradually eliminates the influence of previous
loading; the evolution of the dislocation density under cycling loading,
leading to characteristic `butterfly' curves; and others
Do the photometric colors of Type II-P Supernovae allow accurate determination of host galaxy extinction?
We present infrared photometry of SN 1999em, plus optical photometry,
infrared photometry, and optical spectroscopy of SN 2003hn. Both objects were
Type II-P supernovae. The V-[RIJHK] color curves of these supernovae evolved in
a very similar fashion until the end of plateau phase. This allows us to
determine how much more extinction the light of SN 2003hn suffered compared to
SN 1999em. Since we have an estimate of the total extinction suffered by SN
1999em from model fits of ground-based and space-based spectra as well as
photometry of SN 1999em, we can estimate the total extinction and absolute
magnitudes of SN 2003hn with reasonable accuracy. Since the host galaxy of SN
2003hn also produced the Type Ia SN 2001el, we can directly compare the
absolute magnitudes of these two SNe of different types.Comment: 24 pages, 6 figure
Self-assembled nanoparticle antiglare coatings
Here we report a simple and scalable bottom-up technology for assembling close-packed nanoparticle monolayers on both sides of a glass substrate as high-quality antiglare coatings. Optical measurements show that monolayer coatings consisting of 110 nm silica nanoparticles can significantly reduce optical reflectance and enhance specular transmittance of the glass substrate for a broad range of visible wavelengths. Both experiments and numerical simulations reveal that the antiglare properties of the self-assembled colloidal monolayers are significantly affected by the size of the colloidal particles
Equilibrium properties of a Josephson junction ladder with screening effects
In this paper we calculate the ground state phase diagram of a Josephson
Junction ladder when screening field effects are taken into account. We study
the ground state configuration as a function of the external field, the
penetration depth and the anisotropy of the ladder, using different
approximations to the calculation of the induced fields. A series of tongues,
characterized by the vortex density , is obtained. The vortex density
of the ground state, as a function of the external field, is a Devil's
staircase, with a plateau for every rational value of . The width of
each of these steps depends strongly on the approximation made when calculating
the inductance effect: if the self-inductance matrix is considered, the
phase tends to occupy all the diagram as the penetration depth
decreases. If, instead, the whole inductance matrix is considered, the width of
any step tends to a non-zero value in the limit of very low penetration depth.
We have also analyzed the stability of some simple metastable phases: screening
fields are shown to enlarge their stability range.Comment: 16 pp, RevTex. Figures available upon request at
[email protected] To be published in Physical Review B (01-Dec-96
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