7,282 research outputs found
Mucin Hypersecreting Intraductal Papillary Neoplasm of the Pancreas
Mucin Hypersecreting Intraductal Papillary Neoplasm
is a rare neoplasm that arises from ductal
epithelial cells. This entity is distinct from the more
commonly known Mucinous Cystadenoma or Mucinous
Cystadenocarcinoma. Despite this distinction,
it has been erroneously categorized with these
more common cystic neoplasms. Characteristic clinical
presentation, radiographic, and endoscopic
findings help distinguish this neoplasm from the
cystadenomas and cystadenocarcinomas. Histopathologic
identification is not crucial to the
preoperative diagnosis. This neoplasm is considered
to represent a premalignant condition and, therefore,
surgical resection is warranted. Prognosis,
following resection, is felt to be curative for the
majority of patients
Detectable HIV Viral Load in Kenya: Data from a Population-Based Survey.
IntroductionAt the individual level, there is clear evidence that Human Immunodeficiency Virus (HIV) transmission can be substantially reduced by lowering viral load. However there are few data describing population-level HIV viremia especially in high-burden settings with substantial under-diagnosis of HIV infection. The 2nd Kenya AIDS Indicator Survey (KAIS 2012) provided a unique opportunity to evaluate the impact of antiretroviral therapy (ART) coverage on viremia and to examine the risks for failure to suppress viral replication. We report population-level HIV viral load suppression using data from KAIS 2012.MethodsBetween October 2012 to February 2013, KAIS 2012 surveyed household members, administered questionnaires and drew serum samples to test for HIV and, for those found to be infected with HIV, plasma viral load (PVL) was measured. Our principal outcome was unsuppressed HIV viremia, defined as a PVL ≥ 550 copies/mL. The exposure variables included current treatment with ART, prior history of an HIV diagnosis, and engagement in HIV care. All point estimates were adjusted to account for the KAIS 2012 cluster sampling design and survey non-response.ResultsOverall, 61·2% (95% CI: 56·4-66·1) of HIV-infected Kenyans aged 15-64 years had not achieved virological suppression. The base10 median (interquartile range [IQR]) and mean (95% CI) VL was 4,633 copies/mL (0-51,596) and 81,750 copies/mL (59,366-104,134), respectively. Among 266 persons taking ART, 26.1% (95% CI: 20.0-32.1) had detectable viremia. Non-ART use, younger age, and lack of awareness of HIV status were independently associated with significantly higher odds of detectable viral load. In multivariate analysis for the sub-sample of patients on ART, detectable viremia was independently associated with younger age and sub-optimal adherence to ART.DiscussionThis report adds to the limited data of nationally-representative surveys to report population- level virological suppression. We established heterogeneity across the ten administrative and HIV programmatic regions on levels of detectable viral load. Timely initiation of ART and retention in care are crucial for the elimination of transmission of HIV through sex, needle and syringe use or from mother to child. Further refinement of geospatial mapping of populations with highest risk of transmission is necessary
Unraveling the causes of radiation belt enhancements
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94606/1/eost16149.pd
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The tarantula toxin GxTx detains K+ channel gating charges in their resting conformation.
Allosteric ligands modulate protein activity by altering the energy landscape of conformational space in ligand-protein complexes. Here we investigate how ligand binding to a K+ channel's voltage sensor allosterically modulates opening of its K+-conductive pore. The tarantula venom peptide guangxitoxin-1E (GxTx) binds to the voltage sensors of the rat voltage-gated K+ (Kv) channel Kv2.1 and acts as a partial inverse agonist. When bound to GxTx, Kv2.1 activates more slowly, deactivates more rapidly, and requires more positive voltage to reach the same K+-conductance as the unbound channel. Further, activation kinetics are more sigmoidal, indicating that multiple conformational changes coupled to opening are modulated. Single-channel current amplitudes reveal that each channel opens to full conductance when GxTx is bound. Inhibition of Kv2.1 channels by GxTx results from decreased open probability due to increased occurrence of long-lived closed states; the time constant of the final pore opening step itself is not impacted by GxTx. When intracellular potential is less than 0 mV, GxTx traps the gating charges on Kv2.1's voltage sensors in their most intracellular position. Gating charges translocate at positive voltages, however, indicating that GxTx stabilizes the most intracellular conformation of the voltage sensors (their resting conformation). Kinetic modeling suggests a modulatory mechanism: GxTx reduces the probability of voltage sensors activating, giving the pore opening step less frequent opportunities to occur. This mechanism results in K+-conductance activation kinetics that are voltage-dependent, even if pore opening (the rate-limiting step) has no inherent voltage dependence. We conclude that GxTx stabilizes voltage sensors in a resting conformation, and inhibits K+ currents by limiting opportunities for the channel pore to open, but has little, if any, direct effect on the microscopic kinetics of pore opening. The impact of GxTx on channel gating suggests that Kv2.1's pore opening step does not involve movement of its voltage sensors
Infall, the Butcher-Oemler Effect, and the Descendants of Blue Cluster Galaxies at z~0.6
Using wide-field HST/WFPC2 imaging and extensive Keck/LRIS spectroscopy, we
present a detailed study of the galaxy populations in MS2053--04, a massive,
X-ray luminous cluster at z=0.5866. Analysis of 149 confirmed cluster members
shows that MS2053 is composed of two structures that are gravitationally bound
to each other; their respective velocity dispersions are 865 km/s (113 members)
and 282 km/s (36 members). MS2053's total dynamical mass is 1.2x10^15 Msun.
MS2053 is a classic Butcher-Oemler cluster with a high fraction of blue members
(24%) and an even higher fraction of star-forming members (44%), as determined
from their [OII] emission. The number fraction of blue/star-forming galaxies is
much higher in the infalling structure than in the main cluster. This result is
the most direct evidence to date that the Butcher-Oemler effect is linked to
galaxy infall. In terms of their colors, luminosities, estimated internal
velocity dispersions, and [OII] equivalent widths, the infalling galaxies are
indistinguishable from the field population. MS2053's deficit of S0 galaxies
combined with its overabundance of blue spirals implies that many of these
late-types will evolve into S0 members. The properties of the blue cluster
members in both the main cluster and infalling structure indicate they will
evolve into low mass, L<L* galaxies with extended star formation histories like
that of low mass S0's in Coma. Our observations show that most of MS2053's blue
cluster members, and ultimately most of its low mass S0's, originate in the
field. Finally, we measure the redshift of the giant arc in MS2053 to be
z=3.1462; this object is one in only a small set of known strongly lensed
galaxies at z>3.Comment: Accepted by ApJ. Version with full resolution figures available at
http://www.exp-astro.phys.ethz.ch/tran/outgoing/ms2053.ps.g
Elevated glutamatergic compounds in pregenual anterior cingulate in pediatric autism spectrum disorder demonstrated by 1H MRS and 1H MRSI.
Recent research in autism spectrum disorder (ASD) has aroused interest in anterior cingulate cortex and in the neurometabolite glutamate. We report two studies of pregenual anterior cingulate cortex (pACC) in pediatric ASD. First, we acquired in vivo single-voxel proton magnetic resonance spectroscopy ((1)H MRS) in 8 children with ASD and 10 typically developing controls who were well matched for age, but with fewer males and higher IQ. In the ASD group in midline pACC, we found mean 17.7% elevation of glutamate + glutamine (Glx) (p<0.05) and 21.2% (p<0.001) decrement in creatine + phosphocreatine (Cr). We then performed a larger (26 subjects with ASD, 16 controls) follow-up study in samples now matched for age, gender, and IQ using proton magnetic resonance spectroscopic imaging ((1)H MRSI). Higher spatial resolution enabled bilateral pACC acquisition. Significant effects were restricted to right pACC where Glx (9.5%, p<0.05), Cr (6.7%, p<0.05), and N-acetyl-aspartate + N-acetyl-aspartyl-glutamate (10.2%, p<0.01) in the ASD sample were elevated above control. These two independent studies suggest hyperglutamatergia and other neurometabolic abnormalities in pACC in ASD, with possible right-lateralization. The hyperglutamatergic state may reflect an imbalance of excitation over inhibition in the brain as proposed in recent neurodevelopmental models of ASD
NSF S-STEM Project Update: A Pathway to Completion for Pursuing Engineering and Engineering Technology Degrees
This poster showcases the progress of students who are receiving scholarships from the National Science Foundation S-STEM project: A Pathway to Completion for Pursuing Engineering and Engineering Technology Degrees. Thus far, 20 academically high-achieving students who demonstrate financial need have participated in the project. Thirty-six scholarships have been awarded to date, in which a maximum of twelve scholarships are awarded per semester; some students have received scholarships multiple times. Students are from electrical engineering, computer engineering, mechanical engineering, civil engineering, civil engineering technology, and modeling and simulation majors. As part of this S-STEM project, students also receive academic support, mentorship related to the development of professional workforce skills, career search skills, and opportunities to participate in industry-related field trips. Role models, many of whom are practicing engineers with STEM degrees and are military veterans, serve as presenters and share their personal career pathways and answer students’ questions in the required one-hour weekly seminar. Although the students participating in this project meet the strenuous academic criteria set by the project (3.0/4.0), many of the students struggle financially, due to having expended their G.I. benefits, which can impede their academic performance and graduation. While many student success programs focus on freshman and sophomore students, what makes this project unique is its focus on enabling student success at the junior and senior years. This project provides a portfolio of different activities for the more mature student, e.g. financial aid through scholarships, community-based learning opportunities, and academic success strategies that enable stronger retention and student completion rates. Project activities are tailored to veterans and adult learners as this group of students is particularly vulnerable given their need to simultaneously juggle academic, family, and financial obligations
Establishing a Pathway to Completion for Pursuing Engineering and Engineering Technology Degrees Through a Scholarship Program at Old Dominion University
There are various barriers facing adult students and veterans completing engineering degrees. Many of these student’s work part- or full-time while in college. In order to help these students, enable high retention rates, and decrease time to graduation require an in-depth understanding of specific student populations, especially ones classified as underrepresented. This paper provides an initial look into the first year of a scholarship program, funded by the National Science Foundation, and student success activities designed to support high-achieving, low-income students with demonstrated financial need pursuing bachelor\u27s degrees in engineering and engineering technology. Support services and scholarships are for veterans who have exhausted their GI Bill Benefits, but have not yet graduated. This paper will give an overview of current academic and mentoring support to increase academic success and workplace readiness, ensuring these students are ready to meet the demands of government, industry, and business
Tiny scale opacity fluctuations from VLBA, MERLIN and VLA observations of HI absorption toward 3C 138
The structure function of opacity fluctuations is a useful statistical tool
to study tiny scale structures of neutral hydrogen. Here we present high
resolution observation of HI absorption towards 3C 138, and estimate the
structure function of opacity fluctuations from the combined VLA, MERLIN and
VLBA data. The angular scales probed in this work are ~ 10-200 milliarcsec
(about 5-100 AU). The structure function in this range is found to be well
represented by a power law S_tau(x) ~ x^{beta} with index beta ~ 0.33 +/- 0.07
corresponding to a power spectrum P_tau(U) ~ U^{-2.33}. This is slightly
shallower than the earlier reported power law index of ~ 2.5-3.0 at ~ 1000 AU
to few pc scales. The amplitude of the derived structure function is a factor
of ~ 20-60 times higher than the extrapolated amplitude from observation of Cas
A at larger scales. On the other hand, extrapolating the AU scale structure
function for 3C 138 predicts the observed structure function for Cas A at the
pc scale correctly. These results clearly establish that the atomic gas has
significantly more structures in AU scales than expected from earlier pc scale
observations. Some plausible reasons are identified and discussed here to
explain these results. The observational evidence of a shallower slope and the
presence of rich small scale structures may have implications for the current
understanding of the interstellar turbulence.Comment: 6 pages, 5 figures. Accepted for publication in ApJ. The definitive
version will be available at http://iopscience.iop.org
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