1,028 research outputs found
A Study of Dopamine Metabolism in a Patient with Juvenile Parkinsonism by Positron Emission Tomography
開始ページ、終了ページ: 冊子体のページ付
Overview of soil erosion from irrigation
Of the 15,000,000 ha (37,000,000 acres) of irrigated land in the U.S.,
21% is affected by soil erosion to some extent. Irrigation-induced soil erosion has
been studied, primarily in the Northwestern United States, since 1940. A number
of studies have measured annual sediment yields from furrow-irrigated fields exceeding
20 t/ha (9 tons/acre) with some fields exceeding 100 t/ha (45 tons/acre).
Under the center-pivot sprinkler method, sediment yields as high as 33 t/ha (15
tons/acre) have been measured. Annual sediment yields as high as 4.5 t/ha (2 tons/
acre) were measured from irrigation tracts. Erosion is seldom excessive on slopes
less than 1% and is often excessive on slopes greater than 2%. Erosion reduces
the agricultural productivity of the fields and causes off-farm damages. In southern
Idaho, crop yield potential has been reduced by 25% due to 80 years of irrigation-induced
erosion. Some irrigation districts spend more than $50,000 annually to
remove sediment from drains. Sediment in irrigation return flows causes major
water-quality degredation problems in several rivers in the Western United State
Theoretical description of adiabatic laser alignment and mixed-field orientation: the need for a non-adiabatic model
We present a theoretical study of recent laser-alignment and
mixed-field-orientation experiments of asymmetric top molecules. In these
experiments, pendular states were created using linearly polarized strong ac
electric fields from pulsed lasers in combination with weak electrostatic
fields. We compare the outcome of our calculations with experimental results
obtained for the prototypical large molecule benzonitrile (CHN) [J.L.
Hansen et al, Phys. Rev. A, 83, 023406 (2011)] and explore the directional
properties of the molecular ensemble for several field configurations, i.e.,
for various field strengths and angles between ac and dc fields. For
perpendicular fields one obtains pure alignment, which is well reproduced by
the simulations. For tilted fields, we show that a fully adiabatic description
of the process does not reproduce the experimentally observed orientation, and
it is mandatory to use a diabatic model for population transfer between
rotational states. We develop such a model and compare its outcome to the
experimental data confirming the importance of non-adiabatic processes in the
field-dressed molecular dynamics.Comment: 11 pages, 9 figure
Characterization of electrostatic shock in laser-produced optically-thin plasma flows using optical diagnostics
We present a method for evaluating the properties of electrostatic shock in laser-produced plasmas by using optical diagnostics. A shock is formed by a collimated jet in counter-streaming plasmas in nearly collisionless condition, showing the steepening of the transition width in time. In the present experiment, a streaked optical pyrometry was applied to evaluate the electron density and temperatures in the upstream and downstream regions of the shock so that the shock conditions are satisfied, by assuming thermal bremsstrahlung emission in optically thin plasmas. The derived electron densities are nearly consistent with those estimated from interferometry
Effects of ecstasy/polydrug use on memory for associative information
Rationale
Associative learning underpins behaviours that are fundamental to the everyday functioning of the individual. Evidence pointing to learning deficits in recreational drug users merits further examination.
Objectives
A word pair learning task was administered to examine associative learning processes in ecstasy/polydrug users.
Methods
After assignment to either single or divided attention conditions, 44 ecstasy/polydrug users and 48 non-users were presented with 80 word pairs at encoding. Following this, four types of stimuli were presented at the recognition phase: the words as originally paired (old pairs), previously presented words in different pairings (conjunction pairs), old words paired with new words, and pairs of new words (not presented previously). The task was to identify which of the stimuli were intact old pairs.
Results
Ecstasy/ploydrug users produced significantly more false-positive responses overall compared to non-users. Increased long-term frequency of ecstasy use was positively associated with the propensity to produce false-positive responses. It was also associated with a more liberal signal detection theory decision criterion value. Measures of long term and recent cannabis use were also associated with these same word pair learning outcome measures. Conjunction word pairs, irrespective of drug use, generated the highest level of false-positive responses and significantly more false-positive responses were made in the divided attention condition compared to the single attention condition.
Conclusions
Overall, the results suggest that long-term ecstasy exposure may induce a deficit in associative learning and this may be in part a consequence of users adopting a more liberal decision criterion value
Limb-girdle muscular dystrophy 1F is caused by a microdeletion in the transportin 3 gene
In 2001, we reported linkage of an autosomal dominant form of limb-girdle muscular dystrophy, limb-girdle muscular dystrophy 1F, to chromosome 7q32.1-32.2, but the identity of the mutant gene was elusive. Here, using a whole genome sequencing strategy, we identified the causative mutation of limb-girdle muscular dystrophy 1F, a heterozygous single nucleotide deletion (c.2771del) in the termination codon of transportin 3 (TNPO3). This gene is situated within the chromosomal region linked to the disease and encodes a nuclear membrane protein belonging to the importin beta family. TNPO3 transports serine/arginine-rich proteins into the nucleus, and has been identified as a key factor in the HIV-import process into the nucleus. The mutation is predicted to generate a 15-amino acid extension of the C-terminus of the protein, segregates with the clinical phenotype, and is absent in genomic sequence databases and a set of >200 control alleles. In skeletal muscle of affected individuals, expression of the mutant messenger RNA and histological abnormalities of nuclei and TNPO3 indicate altered TNPO3 function. Our results demonstrate that the TNPO3 mutation is the cause of limb-girdle muscular dystrophy 1F, expand our knowledge of the molecular basis of muscular dystrophies and bolster the importance of defects of nuclear envelope proteins as causes of inherited myopathies
Cooperative coupling of ultracold atoms and surface plasmons
Cooperative coupling between optical emitters and light fields is one of the
outstanding goals in quantum technology. It is both fundamentally interesting
for the extraordinary radiation properties of the participating emitters and
has many potential applications in photonics. While this goal has been achieved
using high-finesse optical cavities, cavity-free approaches that are broadband
and easy to build have attracted much attention recently. Here we demonstrate
cooperative coupling of ultracold atoms with surface plasmons propagating on a
plane gold surface. While the atoms are moving towards the surface they are
excited by an external laser pulse. Excited surface plasmons are detected via
leakage radiation into the substrate of the gold layer. A maximum Purcell
factor of is reached at an optimum distance of
from the surface. The coupling leads to the observation of
a Fano-like resonance in the spectrum.Comment: 9 pages, 4 figure
Pathogenic role of delta 2 tubulin in bortezomib-induced peripheral neuropathy
The pathogenesis of chemotherapy-induced peripheral neuropathy (CIPN) is poorly understood. Here, we report that the CIPN-causing drug bortezomib (Bort) promotes delta 2 tubulin (D2) accumulation while affecting microtubule stability and dynamics in sensory neurons in vitro and in vivo and that the accumulation of D2 is predominant in unmyelinated fibers and a hallmark of bortezomib-induced peripheral neuropathy (BIPN) in humans. Furthermore, while D2 overexpression was sufficient to cause axonopathy and inhibit mitochondria motility, reduction of D2 levels alleviated both axonal degeneration and the loss of mitochondria motility induced by Bort. Together, our data demonstrate that Bort, a compound structurally unrelated to tubulin poisons, affects the tubulin cytoskeleton in sensory neurons in vitro, in vivo, and in human tissue, indicating that the pathogenic mechanisms of seemingly unrelated CIPN drugs may converge on tubulin damage. The results reveal a previously unrecognized pathogenic role for D2 in BIPN that may occur through altered regulation of mitochondria motility
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