12,896 research outputs found
Fast 2.5D Finite Element Simulations of Borehole Resistivity Measurements
We develop a rapid 2.5-dimensional (2.5D) finite element method for simulation of borehole resistivity measurements in transversely isotropic (TI) media. The method combines arbitrary high-order - and (curl)-conforming spatial discretizations. It solves problems where material properties remain constant along one spatial direction, over which we consider a Fourier series expansion and each Fourier mode is solved independently. We propose a novel a priori method to construct quasi-optimal discretizations in physical and Fourier space. This construction is based on examining the analytical (fundamental) solution of the 2.5D formulation over multiple homogeneous spaces and assuming that some of its properties still hold for the 2.5D problem over a spatially heterogeneous formation. In addition, a simple parallelization scheme over multiple measurement positions provides efficient scalability. Our method yields accurate borehole logging simulations for realistic synthetic examples, delivering simulations of borehole resistivity measurements at a rate faster than 0.05 s per measurement location along the well trajectory on a 96-core computer
The Caveolin-1 Connection to Cell Death and Survival
Nunez, S (Nunez, S.)[ 1,4 ] 1. Fac Med, CEMC, Lab Comunicac Celulares, Santiago, Chile. 4. Univ Talca, Fac Hlth Sci, Talca, ChileCaveolins are a family of membrane proteins required for the formation of small plasma membrane invaginations called caveolae that are implicated in cellular trafficking processes. In addition to this structural role, these scaffolding proteins modulate numerous intracellular signaling pathways; often via direct interaction with specific binding partners. Caveolin-1 is particularly well-studied in this respect and has been attributed a large variety of functions. Thus, Caveolin-1 also represents the best-characterized isoform of this family with respect to its participation in cancer. Rather strikingly, available evidence indicates that Caveolin-1 belongs to a select group of proteins that function, depending on the cellular settings, both as tumor suppressor and promoter of cellular traits commonly associated with enhanced malignant behavior, such as metastasis and multi-drug resistance. The mechanisms underlying such ambiguity in Caveolin-1 function constitute an area of great interest. Here, we will focus on discussing how Caveolin-1 modulates cell death and survival pathways and how this may contribute to a better understanding of the ambiguous role this protein plays in cancer
Differential Functional Roles of ALDH1A1 and ALDH1A3 in Mediating Metastatic Behavior and Therapy Resistance of Human Breast Cancer Cells
Previous studies indicate that breast cancer cells with high aldehyde dehydrogenase (ALDH) activity and CD44 expression (ALDHhiCD44+ ) contribute to metastasis and therapy resistance, and that ALDH1 correlates with poor outcome in breast cancer patients. The current study hypothesized that ALDH1 functionally contributes to breast cancer metastatic behavior and therapy resistance. Expression of ALDH1A1 or ALDH1A3 was knocked down in MDA-MB-468 and SUM159 human breast cancer cells using siRNA. Resulting impacts on ALDH activity (Aldefluor® assay); metastatic behavior and therapy response in vitro (proliferation/adhesion/migration/colony formation/chemotherapy and radiation) and extravasation/metastasis in vivo (chick choroiallantoic membrane assay) was assessed. Knockdown of ALDH1A3 but not ALDH1A1 in breast cancer cells decreased ALDH activity, and knockdown of ALDH1A1 reduced breast cancer cell metastatic behavior and therapy resistance relative to control (p \u3c 0.05). In contrast, knockdown of ALDH1A3 did not alter proliferation, extravasation, or therapy resistance, but increased adhesion/migration and decreased colony formation/metastasis relative to control (p \u3c 0.05). This is the first study to systematically examine the function of ALDH1 isozymes in individual breast cancer cell behaviors that contribute to metastasis. Our novel results indicate that ALDH1 mediates breast cancer metastatic behavior and therapy resistance, and that different enzyme isoforms within the ALDH1 family differentially impact these cell behaviors
Polyvinylidene Fluoride Aerogels with Tailorable Crystalline Phase Composition
In this work, polyvinylidene fluoride (PVDF) aerogels with a tailorable phase composition
were prepared by following the crystallization-induced gelation principle. A series of PVDF wet gels
(5 to 12 wt.%) were prepared from either PVDF–DMF solutions or a mixture of DMF and ethanol
as non-solvent. The effects of the non-solvent concentration on the crystalline composition of the
PVDF aerogels were thoroughly investigated. It was found that the nucleating role of ethanol can be
adjusted to produce low-density PVDF aerogels, whereas the changes in composition by the addition
of small amounts of water to the solution promote the stabilization of the valuable β and γ phases.
These phases of the aerogels were monitored by FTIR and Raman spectroscopies. Furthermore, the
crystallization process was followed by in-time and in situ ATR–FTIR spectroscopy. The obtained
aerogels displayed specific surface areas > 150 m2 g−1, with variable particle morphologies that are
dependent on the non-solvent composition, as observed by using SEM and Synchrotron Radiation
Computed micro-Tomography (SR-μC
The High-Mass End of the Red Sequence at z~0.55 from SDSS-III/BOSS: completeness, bimodality and luminosity function
We have developed an analytical method based on forward-modeling techniques
to characterize the high-mass end of the red sequence (RS) galaxy population at
redshift , from the DR10 BOSS CMASS spectroscopic sample, which
comprises galaxies. The method, which follows an unbinned maximum
likelihood approach, allows the deconvolution of the intrinsic CMASS
colour-colour-magnitude distributions from photometric errors and selection
effects. This procedure requires modeling the covariance matrix for the i-band
magnitude, g-r colour and r-i colour using Stripe 82 multi-epoch data. Our
results indicate that the error-deconvolved intrinsic RS distribution is
consistent, within the photometric uncertainties, with a single point
() in the colour-colour plane at fixed magnitude, for a
narrow redshift slice. We have computed the high-mass end () of the -band RS Luminosity Function (RS LF) in several redshift
slices within the redshift range . In this narrow redshift range,
the evolution of the RS LF is consistent, within the uncertainties in the
modeling, with a passively-evolving model with Mpc mag, fading at a rate of mag per
unit redshift. We report RS completeness as a function of magnitude and
redshift in the CMASS sample, which will facilitate a variety of
galaxy-evolution and clustering studies using BOSS. Our forward-modeling method
lays the foundations for future studies using other dark-energy surveys like
eBOSS or DESI, which are affected by the same type of photometric
blurring/selection effects.Comment: 27 pages, 20 figures, accepted for publication in MNRA
Simultaneous multiwavelength observations of the Low/Hard State of the X-ray transient source SWIFT J1753.5-0127
We report the results of simultaneous multiwavelength observations of the
X-ray transient source SWIFT J1753.5-0127 performed with INTEGRAL, RXTE, NTT,
REM and VLA on 2005 August 10-12. The source, which underwent an X-ray outburst
since 2005 May 30, was observed during the INTEGRAL Target of Opportunity
program dedicated to new X-ray novae located in the Galactic Halo. Broad-band
spectra and fast timing variability properties of SWIFT J1753.5-0127 are
analyzed together with the optical, near infra-red and radio data. We show that
the source was significantly detected up to 600 keV with Comptonization
parameters and timing properties typical of the so-called Low/Hard State of
black hole candidates. We build a spectral energy distribution and we show that
SWIFT J1753.5-0127 does not follow the usual radio/X-ray correlation of X-ray
binaries in the Low/Hard State. We give estimates of distance and mass. We
conclude that SWIFT J1753.5-0127 belongs to the X-ray nova class and that it is
likely a black hole candidate transient source of the Galactic Halo which
remained in the Low/Hard State during its main outburst. We discuss our results
within the context of Comptonization and jet models.Comment: Accepted for publication in ApJ, 25 pages, 4 tables, 11 figures (3 in
color
Stationary Configurations Imply Shift Symmetry: No Bondi Accretion for Quintessence / k-Essence
In this paper we show that, for general scalar fields, stationary
configurations are possible for shift symmetric theories only. This symmetry
with respect to constant translations in field space should either be manifest
in the original field variables or reveal itself after an appropriate field
redefinition. In particular this result implies that neither k-Essence nor
Quintessence can have exact steady state / Bondi accretion onto Black Holes. We
also discuss the role of field redefinitions in k-Essence theories. Here we
study the transformation properties of observables and other variables in
k-Essence and emphasize which of them are covariant under field redefinitions.
Finally we find that stationary field configurations are necessarily linear in
Killing time, provided that shift symmetry is realized in terms of these field
variables.Comment: 8 page
The Rapid Evaluation of COVID-19 Vaccination in Emergency Departments for Underserved Patients Study
Early evidence has suggested a high prevalence of acute pulmonary embolism (PE) in Coronavirus 19 (COVID). However, the bulk of existing data evaluates the population of COVID patients admitted to an intensive care unit (ICU). There has been limited evidence in the emergency department (ED) population and as a result, there is variability in diagnostic evaluation for patients presenting with COVID. The objective of this study was to describe the diagnostic evaluation of both COVID positive and negative patients in the ED
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