1,394 research outputs found
Meeting the Vitamin A Requirement: The Efficacy and Importance of β
Vitamin A is essential for life in all vertebrate animals. Vitamin A requirement can be met from dietary preformed vitamin A or provitamin A carotenoids, the most important of which is β-carotene. The metabolism of β-carotene, including its intestinal absorption, accumulation in tissues, and conversion to vitamin A, varies widely across animal species and determines the role that β-carotene plays in meeting vitamin A requirement. This review begins with a brief discussion of vitamin A, with an emphasis on species differences in metabolism. A more detailed discussion of β-carotene follows, with a focus on factors impacting bioavailability and its conversion to vitamin A. Finally, the literature on how animals utilize β-carotene is reviewed individually for several species and classes of animals. We conclude that β-carotene conversion to vitamin A is variable and dependent on a number of factors, which are important to consider in the formulation and assessment of diets. Omnivores and herbivores are more efficient at converting β-carotene to vitamin A than carnivores. Absorption and accumulation of β-carotene in tissues vary with species and are poorly understood. More comparative and mechanistic studies are required in this area to improve the understanding of β-carotene metabolism
Language control and parallel recovery of language in individuals with aphasia
Background: The causal basis of the different patterns of language recovery following stroke in bilingual speakers is not well understood. Our approach distinguishes the representation of language from the mechanisms involved in its control. Previous studies have suggested that difficulties in language control can explain selective aphasia in one language as well as pathological switching between languages. Here we test the hypothesis that difficulties in managing and resolving competition will also be observed in those who are equally impaired in both their languages even in the absence of pathological switching.
Aims: To examine difficulties in language control in bilingual individuals with parallel recovery in aphasia and to compare their performance on different types of conflict task.
Methods & procedures: Two right-handed, non-native English-speaking participants who showed parallel recovery of two languages after stroke and a group of non-native English-speaking, bilingual controls described a scene in English and in their first language and completed three explicit conflict tasks. Two of these were verbal conflict tasks: a lexical decision task in English, in which individuals distinguished English words from non-words, and a Stroop task, in English and in their first language. The third conflict task was a non-verbal flanker task.
Outcomes & Results: Both participants with aphasia were impaired in the picture description task in English and in their first language but showed different patterns of impairment on the conflict tasks. For the participant with left subcortical damage, conflict was abnormally high during the verbal tasks (lexical decision and Stroop) but not during the non-verbal flanker task. In contrast, for the participant with extensive left parietal damage, conflict was less abnormal during the Stroop task than the flanker or lexical decision task.
Conclusions: Our data reveal two distinct control impairments associated with parallel recovery. We stress the need to explore the precise nature of control problems and how control is implemented in order to develop fuller causal accounts of language recovery patterns in bilingual aphasia
Scenarios about the long-time damage of silicon as material and detectors operating beyond LHC collider conditions
For the new hadron collider LHC and some of its updates in luminosity and
energy, as SLHC and VLHC, the silicon detectors could represent an important
option, especially for the tracking system and calorimetry. The main goal of
this paper is to analyse the expected long-time degradation in the bulk of the
silicon as material and for silicon detectors, in continuous radiation field,
in these hostile conditions. The behaviour of silicon in relation to various
scenarios for upgrade in energy and luminosity is discussed in the frame a
phenomenological model developed previously by the authors. Different silicon
material parameters resulting from different technologies are considered to
evaluate what materials are harder to radiation and consequently could minimise
the degradation of device parameters in conditions of continuous long time
operation.Comment: submitted to Physica Scripta Work in the frame of CERN RD-50
Collaboratio
HOPS 361-C's Jet Decelerating and Precessing Through NGC 2071 IR
We present a two-epoch Hubble Space Telescope (HST) near-infrared (NIR) study
of NGC 2071 IR highlighting HOPS 361-C, a protostar producing an arced 0.2
parsec-scale jet. Proper motions for the brightest knots decrease from 350 to
100 km/s with increasing distance from the source. The [Fe II] and Pa
emission line intensity ratio gives a velocity jump through each knot of 40-50
km/s. We show a new [O I] 63 m spectrum taken with the German REciever
for Astronomy at Terahertz frequencies (GREAT) instrument aboard Stratospheric
Observatory for Infrared Astronomy (SOFIA), which give a low jet inclination.
Proper motions and jump velocities then estimate total flow speed throughout
the jet.
We model knot positions and speeds with a precessing jet that decelerates
within the host molecular cloud. The measurements are matched with a precession
period of a few thousand years and half opening angle of 15. The [Fe
II] 1.26 m to 1.64 m line intensity ratio gives the
extinction to each knot ranging from 5-30 mag. Relative to 14 mag of
extinction through the cloud from CO emission maps, the jet is well
embedded at a fractional depth from 1/5 to 4/5, and can interact with the
cloud. Our model suggests the jet is locally dissipated over 0.2 pc. This may
be because knots sweep through a wide angle, giving the cloud time to fill in
cavities opened by the jet. This contrasts with nearly unidirectional
protostellar jets that puncture host clouds and can propagate significantly
further than a quarter pc.Comment: 24 pages, 9 figures, submitted to Ap
The U.S. training institute for dissemination and implementation research in health
Abstract Background The science of dissemination and implementation (D&I) is advancing the knowledge base for how best to integrate evidence-based interventions within clinical and community settings and how to recast the nature or conduct of the research itself to make it more relevant and actionable in those settings. While the field is growing, there are only a few training programs for D&I research; this is an important avenue to help build the field’s capacity. To improve the United States’ capacity for D&I research, the National Institutes of Health and Veterans Health Administration collaborated to develop a five-day training institute for postdoctoral level applicants aspiring to advance this science. Methods We describe the background, goals, structure, curriculum, application process, trainee evaluation, and future plans for the Training in Dissemination and Implementation Research in Health (TIDIRH). Results The TIDIRH used a five-day residential immersion to maximize opportunities for trainees and faculty to interact. The train-the-trainer-like approach was intended to equip participants with materials that they could readily take back to their home institutions to increase interest and further investment in D&I. The TIDIRH curriculum included a balance of structured large group discussions and interactive small group sessions. Thirty-five of 266 applicants for the first annual training institute were accepted from a variety of disciplines, including psychology (12 trainees); medicine (6 trainees); epidemiology (5 trainees); health behavior/health education (4 trainees); and 1 trainee each from education & human development, health policy and management, health services research, public health studies, public policy and social work, with a maximum of two individuals from any one institution. The institute was rated as very helpful by attendees, and by six months after the institute, a follow-up survey (97% return rate) revealed that 72% had initiated a new grant proposal in D&I research; 28% had received funding, and 77% had used skills from TIDIRH to influence their peers from different disciplines about D&I research through building local research networks, organizing formal presentations and symposia, teaching and by leading interdisciplinary teams to conduct D&I research. Conclusions The initial TIDIRH training was judged successful by trainee evaluation at the conclusion of the week’s training and six-month follow-up, and plans are to continue and possibly expand the TIDIRH in coming years. Strengths are seen as the residential format, quality of the faculty and their flexibility in adjusting content to meet trainee needs, and the highlighting of concrete D&I examples by the local host institution, which rotates annually. Lessons learned and plans for future TIDIRH trainings are summarized
The Identification of the X-ray Counterpart to PSR J2021+4026
We report the probable identification of the X-ray counterpart to the
gamma-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray
Observatory ACIS and timing analysis with the Fermi satellite. Given the
statistical and systematic errors, the positions determined by both satellites
are coincident. The X-ray source position is R.A. 20h21m30.733s, Decl. +40 deg
26 min 46.04sec (J2000) with an estimated uncertainty of 1.3 arsec combined
statistical and systematic error. Moreover, both the X-ray to gamma-ray and the
X-ray to optical flux ratios are sensible assuming a neutron star origin for
the X-ray flux. The X-ray source has no cataloged infrared-to-visible
counterpart and, through new observations, we set upper limits to its optical
emission of i' >23.0 mag and r' > 25.2mag. The source exhibits an X-ray
spectrum with most likely both a powerlaw and a thermal component. We also
report on the X-ray and visible light properties of the 43 other sources
detected in our Chandra observation.Comment: Accepted for publication in the Astrophysical Journa
IKK phosphorylates Huntingtin and targets it for degradation by the proteasome and lysosome
Expansion of the polyglutamine repeat within the protein Huntingtin (Htt) causes Huntington's disease, a neurodegenerative disease associated with aging and the accumulation of mutant Htt in diseased neurons. Understanding the mechanisms that influence Htt cellular degradation may target treatments designed to activate mutant Htt clearance pathways. We find that Htt is phosphorylated by the inflammatory kinase IKK, enhancing its normal clearance by the proteasome and lysosome. Phosphorylation of Htt regulates additional post-translational modifications, including Htt ubiquitination, SUMOylation, and acetylation, and increases Htt nuclear localization, cleavage, and clearance mediated by lysosomal-associated membrane protein 2A and Hsc70. We propose that IKK activates mutant Htt clearance until an age-related loss of proteasome/lysosome function promotes accumulation of toxic post-translationally modified mutant Htt. Thus, IKK activation may modulate mutant Htt neurotoxicity depending on the cell's ability to degrade the modified species
Author Correction: A consensus-based transparency checklist.
An amendment to this paper has been published and can be accessed via a link at the top of the paper
Quantum Dot Targeting with Lipoic Acid Ligase and HaloTag for Single-Molecule Imaging on Living Cells
We present a methodology for targeting quantum dots to specific proteins on living cells in two steps. In the first step, Escherichia coli lipoic acid ligase (LplA) site-specifically attaches 10-bromodecanoic acid onto a 13 amino acid recognition sequence that is genetically fused to a protein of interest. In the second step, quantum dots derivatized with HaloTag, a modified haloalkane dehalogenase, react with the ligated bromodecanoic acid to form a covalent adduct. We found this targeting method to be specific, fast, and fully orthogonal to a previously reported and analogous quantum dot targeting method using E. coli biotin ligase and streptavidin. We used these two methods in combination for two-color quantum dot visualization of different proteins expressed on the same cell or on neighboring cells. Both methods were also used to track single molecules of neurexin, a synaptic adhesion protein, to measure its lateral diffusion in the presence of neuroligin, its trans-synaptic adhesion partner.National Institutes of Health (U.S.) (R01 GM072670)Camille & Henry Dreyfus FoundationMassachusetts Institute of Technology. Computational and Systems Biology Program. MIT-Merck Postdoctoral Fellowshi
Cluster of Sylvatic Epidemic Typhus Cases Associated with Flying Squirrels, 2004–2006
Infected persons had slept in an infested cabin
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