3,404 research outputs found
The materials processing research base of the Materials Processing Center
The goals and activities of the center are discussed. The center activities encompass all engineering materials including metals, ceramics, polymers, electronic materials, composites, superconductors, and thin films. Processes include crystallization, solidification, nucleation, and polymer synthesis
Automatic identification of gait events using an instrumented sock
Background: textile-based transducers are an emerging technology in which piezo-resistive properties of materials
are used to measure an applied strain. By incorporating these sensors into a sock, this technology offers the
potential to detect critical events during the stance phase of the gait cycle. This could prove useful in several
applications, such as functional electrical stimulation (FES) systems to assist gait.
Methods: we investigated the output of a knitted resistive strain sensor during walking and sought to determine
the degree of similarity between the sensor output and the ankle angle in the sagittal plane. In addition, we
investigated whether it would be possible to predict three key gait events, heel strike, heel lift and toe off, with a
relatively straight-forward algorithm. This worked by predicting gait events to occur at fixed time offsets from
specific peaks in the sensor signal.
Results: our results showed that, for all subjects, the sensor output exhibited the same general characteristics as
the ankle joint angle. However, there were large between-subjects differences in the degree of similarity between
the two curves. Despite this variability, it was possible to accurately predict gait events using a simple algorithm.
This algorithm displayed high levels of trial-to-trial repeatability.
Conclusions: this study demonstrates the potential of using textile-based transducers in future devices that provide active gait assistance
Research in far ultraviolet filtering for space optical systems
Design and fabrication of multilayer interference filters for ultraviole
The influence of the cluster environment on the star formation efficiency of 12 Virgo spiral galaxies
The influence of the environment on gas surface density and star formation
efficiency of cluster spiral galaxies is investigated. We extend previous work
on radial profiles by a pixel-to pixel analysis looking for asymmetries due to
environmental interactions. The star formation rate is derived from GALEX UV
and Spitzer total infrared data. As in field galaxies, the star formation rate
for most Virgo galaxies is approximately proportional to the molecular gas
mass. Except for NGC 4438, the cluster environment does not affect the star
formation efficiency with respect to the molecular gas. Gas truncation is not
associated with major changes in the total gas surface density distribution of
the inner disk of Virgo spiral galaxies. In three galaxies, possible increases
in the molecular fraction and the star formation efficiency with respect to the
total gas, of factors of 1.5 to 2, are observed on the windward side of the
galactic disk. A significant increase of the star formation efficiency with
respect to the molecular gas content on the windward side of ram
pressure-stripped galaxies is not observed. The ram-pressure stripped
extraplanar gas of 3 highly inclined spiral galaxies shows a depressed star
formation efficiency with respect to the total gas, and one of them (NGC 4438)
shows a depressed rate even with respect to the molecular gas. The
interpretation is that stripped gas loses the gravitational confinement and
associated pressure of the galactic disk, and the gas flow is diverging, so the
gas density decreases and the star formation rate drops. However, the stripped
extraplanar gas in one highly inclined galaxy (NGC 4569) shows a normal star
formation efficiency with respect to the total gas. We propose this galaxy is
different because it is observed long after peak pressure, and its extraplanar
gas is now in a converging flow as it resettles back into the disk.Comment: 34 pages, 24 figures, accepted for publication by A&
Structure in the optical absorption edge of amorphous selenium technical note no. 8
Temperature measurement of absorption spectrum near band edge of amorphous selenium on evaporated samples with and without substrate
Remote sensing of Pacific hurricane and radiometric measurements from foam and slicks
There are no author-identified significant results in this report
Ram-pressure stripped molecular gas in the Virgo spiral galaxy NGC 4522
IRAM 30m 12CO(1-0) and 12CO(2-1) HERA observations are presented for the
ram-pressure stripped Virgo spiral galaxy NGC 4522. The CO emission is detected
in the galactic disk and the extraplanar gas. The extraplanar CO emission
follows the morphology of the atomic gas closely but is less extended. The CO
maxima do not appear to correspond to regions where there is peak massive star
formation as probed by Halpha emission. The presence of molecular gas is a
necessary but not sufficient condition for star formation. Compared to the disk
gas, the molecular fraction of the extraplanar gas is 30% lower and the star
formation efficiency of the extraplanar gas is about 3 times lower. The
comparison with an existing dynamical model extended by a recipe for
distinguishing between atomic and molecular gas shows that a significant part
of the gas is stripped in the form of overdense arm-like structures. It is
argued that the molecular fraction depends on the square root of the total
large-scale density. Based on the combination of the CO/Halpha and an
analytical model, the total gas density is estimated to be about 4 times lower
than that of the galactic disk. Molecules and stars form within this dense gas
according to the same laws as in the galactic disk, i.e. they mainly depend on
the total large-scale gas density. Star formation proceeds where the local
large-scale gas density is highest. Given the complex 3D morphology this does
not correspond to the peaks in the surface density. In the absence of a
confining gravitational potential, the stripped gas arms will most probably
disperse; i.e. the density of the gas will decrease and star formation will
cease.Comment: 11 pages, 15 figures, A&A accepted for publicatio
Humanin G (HNG) protects age-related macular degeneration (AMD) transmitochondrial ARPE-19 cybrids from mitochondrial and cellular damage.
Age-related macular degeneration (AMD) ranks third among the leading causes of visual impairment with a blindness prevalence rate of 8.7%. Despite several treatment regimens, such as anti-angiogenic drugs, laser therapy, and vitamin supplementation, being available for wet AMD, to date there are no FDA-approved therapies for dry AMD. Substantial evidence implicates mitochondrial damage and retinal pigment epithelium (RPE) cell death in the pathogenesis of AMD. However, the effects of AMD mitochondria and Humanin G (HNG), a more potent variant of the mitochondrial-derived peptide (MDP) Humanin, on retinal cell survival have not been elucidated. In this study, we characterized mitochondrial and cellular damage in transmitochondrial cybrid cell lines that contain identical nuclei but possess mitochondria from either AMD or age-matched normal (Older-normal (NL)) subjects. AMD cybrids showed (1) reduced levels of cell viability, lower mtDNA copy numbers, and downregulation of mitochondrial replication/transcription genes and antioxidant enzyme genes; and (2) elevated levels of genes related to apoptosis, autophagy and ER-stress along with increased mtDNA fragmentation and higher susceptibility to amyloid-β-induced toxicity compared to NL cybrids. In AMD cybrids, HNG protected the AMD mitochondria, reduced pro-apoptosis gene and protein levels, upregulated gp130 (a component of the HN receptor complex), and increased the protection against amyloid-β-induced damage. In summary, in cybrids, damaged AMD mitochondria mediate cell death that can be reversed by HNG treatment. Our results also provide evidence of Humanin playing a pivotal role in protecting cells with AMD mitochondria. In the future, it may be possible that AMD patient's blood samples containing damaged mitochondria may be useful as biomarkers for this condition. In conclusion, HNG may be a potential therapeutic target for treatment of dry AMD, a debilitating eye disease that currently has no available treatment. Further studies are needed to establish HNG as a viable mitochondria-targeting therapy for dry AMD
A dynamical model for the heavily ram pressure stripped Virgo spiral galaxy NGC 4522
A dynamical model including ram pressure stripping is applied to the strongly
HI deficient Virgo spiral galaxy NGC 4522. A carefully chosen model snapshot is
compared with existing VLA HI observations. The model successfully reproduces
the large-scale gas distribution and the velocity field. However it fails to
reproduce the large observed HI linewidths in the extraplanar component, for
which we give possible explanations. In a second step, we solve the induction
equation on the velocity fields of the dynamical model and calculate the large
scale magnetic field. Assuming a Gaussian distribution of relativistic
electrons we obtain the distribution of polarized radio continuum emission
which is also compared with our VLA observations at 6 cm. The observed maximum
of the polarized radio continuum emission is successfully reproduced. Our model
suggests that the ram pressure maximum occurred only ~50 Myr ago. Since NGC
4522 is located far away from the cluster center (~1 Mpc) where the
intracluster medium density is too low to cause the observed stripping if the
intracluster medium is static and smooth, two scenarios are envisaged: (i) the
galaxy moves very rapidly within the intracluster medium and is not even bound
to the cluster; in this case the galaxy has just passed the region of highest
intracluster medium density; (ii) the intracluster medium is not static but
moving due to the infall of the M49 group of galaxies. In this case the galaxy
has just passed the region of highest intracluster medium velocity. This study
shows the strength of combining high resolution HI and polarized radio
continuum emission with detailed numerical modeling of the evolution of the gas
and the large-scale magnetic field.Comment: 15 pages, 11 figures, accepted for publication in A&
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