1,881 research outputs found
Alternate routes to the cell surface underpin insulin-regulated membrane trafficking of GLUT4
Insulin-stimulated delivery of glucose transporters (GLUT4) from specialized intracellular GLUT4 storage vesicles (GSVs) to the surface of fat and muscle cells is central to whole-body glucose. This translocation and subsequent internalization of GLUT4 back into intracellular stores transits numerous small membrane-bound compartments (internal GLUT4-containing vesicles; IGVs) including GSVs, but the function of these different compartments is not clear. Cellugyrin and sortilin define distinct populations of IGV; sortilin-positive IGVs represent GSVs, but the function of cellugyrin-containing IGVs is unknown. Here we demonstrate a role for cellugyrin in intracellular sequestration of GLUT4 in HeLa cells and have used a proximity ligation assay to follow changes in pairwise associations between cellugyrin, sortilin, GLUT4 and membrane trafficking machinery following insulin-stimulation of 3T3-L1 adipoctyes. Our data suggest that insulin stimulates traffic from cellugyrin- to sortilin- membranes, and that cellugyrin-IGVs provide an insulin-sensitive reservoir to replenish GSVs following insulin-stimulated exocytosis of GLUT4. Furthermore, our data support the existence of a pathway from cellugyrin-membranes to the surface of 3T3-L1 adipocytes that bypasses GSVs under basal conditions, and that insulin diverts traffic away from this into GSVs
Unveiling the Mysteries of Aceh, Indonesia: Local and Global Intersections of Women\u27s Agency
Forces of globalization, local culture, and Islam continuously inform one another and dynamically manifest in cultures across the world. Scholars often assume that these influences may have distinct and independent effects. However, we argue that these global forces occur simultaneously and they may contradict or complement each other along a spectrum within Aceh, Indonesia. The manifestations and responses vary depending on the nature of the interactions of global and local factors. This spectrum represents various ways in which women negotiate identity and agency, specifically within the context of the implementation of Shari’ah Law. This research investigates the specific ways in which women’s identities influence and are influenced by the globalization of feminism, matrifocal traditions, and Islamic veiling practices in Aceh.
In the summer of 2012, the authors conducted field research in Aceh, Indonesia through interviews and observations. These included over 70 participants and 20 organizations which varied in formality and size. The interview participants include: activists, academicians, spiritual leaders, government officials, law enforcement agents, university students, and other community members from both rural and urban areas
Tight-binding study of the influence of the strain on the electronic properties of InAs/GaAs quantum dots
We present an atomistic investigation of the influence of strain on the
electronic properties of quantum dots (QD's) within the empirical tight-binding (ETB) model with interactions up to 2nd nearest neighbors
and spin-orbit coupling. Results for the model system of capped pyramid-shaped
InAs QD's in GaAs, with supercells containing atoms are presented and
compared with previous empirical pseudopotential results. The good agreement
shows that ETB is a reliable alternative for an atomistic treatment. The strain
is incorporated through the atomistic valence force field model. The ETB
treatment allows for the effects of bond length and bond angle deviations from
the ideal InAs and GaAs zincblende structure to be selectively removed from the
electronic-structure calculation, giving quantitative information on the
importance of strain effects on the bound state energies and on the physical
origin of the spatial elongation of the wave functions. Effects of dot-dot
coupling have also been examined to determine the relative weight of both
strain field and wave function overlap.Comment: 22 pages, 7 figures, submitted to Phys. Rev. B (in press) In the
latest version, added Figs. 3 and 4, modified Fig. 5, Tables I and II,.and
added new reference
Theoretical interpretation of the experimental electronic structure of lens shaped, self-assembled InAs/GaAs quantum dots
We adopt an atomistic pseudopotential description of the electronic structure
of self-assembled, lens shaped InAs quantum dots within the ``linear
combination of bulk bands'' method. We present a detailed comparison with
experiment, including quantites such as the single particle electron and hole
energy level spacings, the excitonic band gap, the electron-electron, hole-hole
and electron hole Coulomb energies and the optical polarization anisotropy. We
find a generally good agreement, which is improved even further for a dot
composition where some Ga has diffused into the dots.Comment: 16 pages, 5 figures. Submitted to Physical Review
Bovine Follicular Dynamics, Oocyte Recovery,and Development of Oocytes Microinjected with a Green Fluorescent Protein Construct
The present study was carried out to 1) evaluate the viability of in vitro fertilized zygotes after microinjection of DNA, 2) assess the influence of oocyte quality upon the development rate of embryos when injected with DNA, and 3) determine the integration frequency of green fluorescent protein DNA into microinjected embryos. Oocytes were aspirated from ovaries of nine nonlactating Holsteins and were categorized into grades A, B, C, and D. At 16 h after in vitro fertilization, approximately half of the pronuclear stage presumptive zygotes were classified as having 1 pronucleus or 2 pronuclei, and they were microinjected with DNA constructs. A potential predictor of DNA integration frequency at d 10 was assessment of the incidence of green fluorescing embryos. The proportion of cleaved embryos that developed to morulae or blastocysts was not different between groups with 1 pronucleus injected (45%), 1 pronucleus uninjected (64%), or 2 pronuclei injected (49%). However, the development of morulae or blastocysts was higher in the group with 2 pronuclei uninjected (69%). The overall developmental score of green fluorescent protein-positive embryos was higher for grade A oocytes (1.3 &#;&#;0.1) than for grade B (0.8 &#; 0.1), C (0.6 &#;&#;0.1), or D (0.3 &#;&#;0.1) oocytes. The results show that production of transgenic bovine blastocysts can occur from the microinjection of a presumptive zygote having only one visible pronucleus. Initial oocyte quality is an important factor in selection of oocytes suitable for microinjection of DNA and for preimplantation development to produce bovine transgenic embryos
Characterizing wind gusts in complex terrain
Wind gusts are a key driver of aerodynamic loading, especially for tall
structures such a bridges and wind turbines. However, gust characteristics in
complex terrain are not well understood and common approximations used to
describe wind gust behavior may not be appropriate at heights relevant to
wind turbines and other structures. Data collected in the Perdigão
experiment are analyzed herein to provide a foundation for improved wind gust
characterization and process-level understanding of flow intermittency in
complex terrain. High-resolution observations from sonic anemometers and
vertically pointing Doppler lidars are used to conduct a detailed study of
gust characteristics with a specific focus on the parent distributions of
nine gust parameters (that describe velocity, time, and length scales), their
joint distributions, height variation, and coherence in the vertical and
horizontal planes. Best-fit distributional forms for varying gust properties
show good agreement with those from previous experiments in moderately
complex terrain but generate nonconservative estimates of the gust properties
that are of key importance to structural loading. Probability distributions
of gust magnitude derived from vertically pointing Doppler lidars exhibit
good agreement with estimates from sonic anemometers despite differences
arising from volumetric averaging and the terrain complexity. Wind speed
coherence functions during gusty periods (which are important to structural
wind loading) are similar to less complex sites for small vertical
displacements (10 to 40 m), but do not exhibit an exponential form for
larger horizontal displacements (800 to 1500 m).</p
A narrative analysis of career transition themes and outcomes using chaos theory as a guiding metaphor
In a rapidly changing world of work little research exists on mid-career transitions. We investigated these using the open-systems approach of chaos theory as a guiding metaphor and conducted interviews with seven mid-career individuals chosen for their experience of a significant mid-career transition. Four common themes were identified through narrative analysis, where ‘false starts’ to a career were a common experience prior to finding a career ‘fit’. Career transitions, precipitated by a trigger state and/or event such as a period of disillusionment, were an important part of this ‘finding a fit’ process. Overall, career success outcomes were shaped by a combination of chaos elements: chance, unplanned events, and non-linearity of resultant outcomes. We discuss implications for future research and for practice
White Dwarfs in Globular Clusters: HST Observations of M4
Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258
white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial
distances from the cluster center were observed and sizeable WD populations
were found in all three. The location of these WDs in the color-magnitude
diagram, their mean mass of 0.51()M, and their luminosity
function confirm basic tenets of stellar evolution theory and support the
results from current WD cooling theory. The WDs are used to extend the cluster
main-sequence mass function upward to stars that have already completed their
nuclear evolution. The WD/red dwarf binary frequency in M4 is investigated and
found to be at most a few percent of all the main-sequence stars. The most
ancient WDs found are about 9 Gyr old, a level which is set solely by the
photometric limits of our data. Even though this is less than the age of M4, we
discuss how these cooling WDs can eventually be used to check the turnoff ages
of globular clusters and hence constrain the age of the Universe.Comment: 46 pages, latex, no figures included, figures available at
ftp://ftp.astro.ubc.ca/pub/richer/wdfig.uu size 2.7Mb. To be published in the
Astrophysical Journa
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