256 research outputs found
Hubble Space Telescope Imaging of the Ultracompact Blue Dwarf Galaxy HS 0822+3542: An Assembling Galaxy in a Local Void?
We present deep U, narrow-V, and I-band images of the ultracompact blue dwarf
galaxy HS 0822+3542, obtained with the Advanced Camera for Surveys / High
Resolution Channel of the Hubble Space Telescope. This object is extremely
metal-poor (12 + log(O/H) = 7.45) and resides in a nearby void. The images
resolve it into two physically separate components that were previously
described as star clusters in a single galaxy. The primary component is only
\~100 pc in maximum extent, and consists of starburst region surrounded by a
ring-like structure of relatively redder stars. The secondary component is ~50
pc in size and lies at a projected distance of ~80 pc away from the primary,
and is also actively star-forming. We estimate masses ~10^7 M(sol) and ~10^6
M(sol) for the two components, based on their luminosities, with an associated
dynamical timescale for the system of a few Myr. This timescale and the
structure of the components suggests that a collision between them triggered
their starbursts. The spectral energy distributions of both components can be
fitted by the combination of recent (few Myr old) starburst and an evolved
(several Gyr old) underlying stellar population, similar to larger blue compact
dwarf galaxies. This indicates that despite its metal deficiency the object is
not forming its first generation of stars. However, the small sizes and masses
of the two components suggests that HS 0822+3542 represents a dwarf galaxy in
the process of assembling from clumps of stars intermediate in size between
globular clusters and objects previously classified as galaxies. Its relatively
high ratio of neutral gas mass to stellar mass (~1) and high specific star
formation rate, log(SFR/M(sol) = -9.2, suggests that it is still converting
much of its gas to stars.Comment: 11 pages, 2 figures, accepted for publication in Astrophysical
Journal Letter
Mind over milkshakes: mindsets, not just nutrients, determine ghrelin response
Objective: To test whether physiological satiation as measured by the gut peptide ghrelin may vary depending on the mindset in which one approaches consumption of food. Methods: On 2 separate occasions, participants (n Ď 46) consumed a 380-calorie milkshake under the pretense that it was either a 620-calorie "indulgent" shake or a 140-calorie "sensible" shake. Ghrelin was measured via intravenous blood samples at 3 time points: baseline (20 min), anticipatory (60 min), and postconsumption (90 min). During the first interval (between 20 and 60 min) participants were asked to view and rate the (misleading) label of the shake. During the second interval (between 60 and 90 min) participants were asked to drink and rate the milkshake. Results: The mindset of indulgence produced a dramatically steeper decline in ghrelin after consuming the shake, whereas the mindset of sensibility produced a relatively flat ghrelin response. Participants' satiety was consistent with what they believed they were consuming rather than the actual nutritional value of what they consumed. Conclusions: The effect of food consumption on ghrelin may be psychologically mediated, and mindset meaningfully affects physiological responses to food
Hinge for Use in a Tension Stiffened and Tendon Actuated Manipulator
A tension stiffened and tendon actuated manipulator is provided performing robotic-like movements when acquiring a payload. The manipulator design can be adapted for use in-space, lunar or other planetary installations as it is readily configurable for acquiring and precisely manipulating a payload in both a zero-g environment and in an environment with a gravity field. The manipulator includes a plurality of link arms, a hinge connecting adjacent link arms together to allow the adjacent link arms to rotate relative to each other and a cable actuation and tensioning system provided between adjacent link arms. The cable actuation and tensioning system includes a spreader arm and a plurality of driven and non-driven elements attached to the link arms and the spreader arm. At least one cable is routed around the driven and non-driven elements for actuating the hinge
Development of Silica-Immobilized Vaccines for Improving Thermo-Tolerance and Shelf-Life
Introduction. It is estimated that 50% of vaccines produced annu- ally are wasted because effectivity is dependent on protein structure and heat exposure disrupts the intermolecular interactions that maintain this structure. Since 90% of vaccines require a temperature- controlled supply chain, it is necessary to create a cold chain system to minimize vaccine waste. We have developed a more sustainable technology via the adsorption of Invasion Plasmid Antigen D (IpaD) onto mesoporous silica gels, improving the thermal stability of pro- tein-based therapeutics.
Methods.xThe solution depletion method using UV-Vis was uti- lized to study the adsorption of IpaD onto silica gels. The silica-IpaD complex is heated above the denaturing temperature of the protein and then the IpaD is removed using N,N-Dimethyldodecylamine N-oxide (LDAO) and their secondary structure is tested using cir- cular dichroism (CD).
Results. Pore diameter, pore volume and surface area were charac- terized for seven different silica gels. Silica gels designated as 6389, 6378, and 6375 had an adsorption percentage above 95% at pore volumes of 2.2, 2.8 and 3.8 cm3 mg-1, respectively. CD analyses con- firmed that the adsorbed IpaD after the heat treatment displayed a similar “W” shape CD signal as the native IpaD, indicating the con- servation of α-helices. In contrast, the unprotected IpaD after being exposed to high temperature shows a flat CD signal, demonstrating the loss of secondary structure.
Conclusion. We have successfully increased the thermo-tolerance for IpaD using mesoporous silica and continue to further optimize mesoporous silica’s physiochemical properties to improve adsorption and desorption yields
Preliminary validation of the Yale Food Addiction Scale.
Introduction: Evidence is growing that an addictive process may play a role in problematic eating behavior. The majority of research on this topic has examined the concept of "food addiction" solely in adult samples. If certain foods have addictive potential, children may be impacted as much as (or more) than adults due to psychological and neurobiological vulnerabilities at younger developmental stages. In the current study, we developed a measure of food addiction in children that reflects the diagnostic indicators of addiction. Materials and methods: The content and reading level of the Yale Food Addiction Scale (YFAS) was altered to be appropriate for children (YFAS-C). The YFAS-C and other eating-related measures were administered to study participants to examine the validity and reliability of the YFAS-C. Participants: 75 children were recruited from the community ranging from lean to obese. Results: The validation of the YFAC-C provides preliminary support for its convergent validity with like constructs and incremental validity in predicting body mass index. Internal consistency was adequate given the small number of items on the scale. Discussion: The YFAS-C appears to be a helpful tool for identifying addictive-like eating in children
Preliminary validation of the Yale Food Addiction Scale for children
Evidence is growing that an addictive process may play a role in problematic eating behavior. The majority of research on this topic has examined the concept of “food addiction” solely in adult samples. If certain foods have addictive potential, children may be impacted as much as (or more) than adults due to psychological and neurobiological vulnerabilities at younger developmental stages. In the current study, we developed a measure of food addiction in children that reflects the diagnostic indicators of addiction
POX 186: A Dwarf Galaxy in the Process of Formation?
We present deep U, V and I band images of the "ultracompact" blue dwarf
galaxy POX 186 obtained with the Planetary Camera 2 of the Hubble Space
Telescope. We have also obtained a near-ultraviolet spectrum of the object with
the Space Telescope Imaging Spectrograph, and combine this with a new
ground-based optical spectrum. The images confirm the galaxy to be extremely
small, with a maximum extent of only 300 pc, a luminosity ~ 10^-4 L*, and an
estimated mass ~ 10^7 M(sun). Its morphology is highly asymmetric, with a tail
of material on its western side that may be tidal in origin. The U-band image
shows this tail to be part of a stream of material in which stars have recently
formed. Most of the star formation in the galaxy is however concentrated in a
central, compact (d ~ 10 - 15 pc) star cluster. The outer regions of the galaxy
are significantly redder than the cluster, with V - I colors consistent with a
population dominated by K and M stars. While these results rule out earlier
speculation that POX 186 is a protogalaxy, its morphology, mass and active star
formation suggest that it represents a recent (within ~ 10^8 yr) collision
between two clumps of stars of sub-galactic size (~ 100 pc). POX 186 may thus
be a very small dwarf galaxy that, dynamically speaking, is still in the
process of formation. This interpretation is supported by the fact that it
resides in a void, so its morphology cannot be explained as the result of an
encounter with a more massive galaxy. Clumps of stars this small may represent
the building blocks required by hierarchical models of galaxy formation, and
these results also support the recent "downsizing" picture of galaxy formation
in which the least massive objects are the last to form.Comment: accepted for publication in ApJ; 23 pages, 5 figure
Ultracompact Blue Dwarf Galaxies: Hubble Space Telescope Imaging and Stellar Population Analysis
We present deep Hubble Space Telescope Advanced Camera for Surveys / High
Resolution Channel U, narrow-V, and I images of nine "ultracompact" blue dwarf
galaxies (UCBDs) selected from the Sloan Digital Sky Survey. We define UCBDs as
local (z < 0.01) star-forming galaxies having angular diameters < 6" and
physical sizes < 1 kpc. They are also among the most metal-poor galaxies known,
and are found to reside within voids. Both the HST images and the objects'
optical spectra reveal that they are composites of young (~1 Myr) populations
that dominate their light, and older (~10 Gyr) populations that dominate their
stellar masses, which we estimate to be ~10^7 - 10^8 Msol. An intermediate-age
population is also indicated in most cases. The objects are not as dynamically
disturbed as the prototype UCBD, POX 186, but the structure of several of them
suggests that their current starbursts have been triggered by the
collisions/mergers of smaller clumps of stars. In one case, HS 0822+3542, the
ACS/HRC images resolve the object into two small (~100 pc) components which
appear to have recently collided, supporting this interpretation. In six of the
objects much of their star formation is concentrated in Young Massive Star
clusters. The evidence that the galaxies consist mainly of ~10 Gyr old stars
establishes that they are not protogalaxies; their low metallicities are more
likely to be the result of the escape of supernova ejecta, as opposed to youth.
These results are consistent with recent galaxy formation simulations which
predict that cosmic re-ionization at z ~ 6 significantly limited the subsequent
star formation of dwarf galaxies in voids due to the photo-evaporation of
baryons from their cold dark matter halos (Abridged).Comment: 43 pages, 6 figures, accepted for publication in ApJ; figures
available at ftp://ftp.nofs.navy.mil/pub/outgoing/mcorbin
Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas
This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing
molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin
Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context
Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts
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