1,793 research outputs found
Investigating Mitophagy and Mitochondrial Morphology In Vivo Using mito-QC:A Comprehensive Guide
Passive Aeroelastic Tailored Wing Modal Test Using the Fixed Base Correction Method
In modal testing and finite element model correlation, analysts desire modal results using free-free or rigid boundary conditions to ease comparisons of test versus analytical data. It is often expensive both in cost and schedule to build and test with boundary conditions that replicate the free-free or rigid boundaries. Static test fixtures for load testing are often large, heavy, and unyielding, but do not provide adequate boundaries for modal tests because they are dynamically too flexible and often contain natural frequencies within the frequency range of interest of the test article. Dynamic coupling between the test article and test fixture complicates the model updating process because significant effort is required to model the test fixture and boundary conditions in addition to the test article. If there were a way to correct the modal results for fixture coupling, then setups used for other structural testing could be adequate for modal testing. In the case described in this paper, a partial static loads testing setup was used, which allowed significant schedule and cost savings by eliminating a unique setup for a modal test. A fixed base correction technique was investigated during modal testing of a flexible wing cantilevered from part of a static test fixture. The technique was successfully used to measure the wing modes de-coupled from the dynamically active test fixture. The technique is promising for future aircraft applications, but more research is needed
Bifidobacterium longum 1714 as a translational psychobiotic: modulation of stress, electrophysiology and neurocognition in healthy volunteers
The emerging concept of psychobioticsâlive microorganisms with a potential mental health benefitârepresents a novel approach for the management of stress-related conditions. The majority of studies have focused on animal models. Recent preclinical studies have identified the B. longum 1714 strain as a putative psychobiotic with an impact on stress-related behaviors, physiology and cognitive performance. Whether such preclinical effects could be translated to healthy human volunteers remains unknown. We tested whether psychobiotic consumption could affect the stress response, cognition and brain activity patterns. In a within-participants design, healthy volunteers (N=22) completed cognitive assessments, resting electroencephalography and were exposed to a socially evaluated cold pressor test at baseline, post-placebo and post-psychobiotic. Increases in cortisol output and subjective anxiety in response to the socially evaluated cold pressor test were attenuated. Furthermore, daily reported stress was reduced by psychobiotic consumption. We also observed subtle improvements in hippocampus-dependent visuospatial memory performance, as well as enhanced frontal midline electroencephalographic mobility following psychobiotic consumption. These subtle but clear benefits are in line with the predicted impact from preclinical screening platforms. Our results indicate that consumption of B. longum 1714 is associated with reduced stress and improved memory. Further studies are warranted to evaluate the benefits of this putative psychobiotic in relevant stress-related conditions and to unravel the mechanisms underlying such effects
TADPOLE Challenge: Accurate Alzheimer's disease prediction through crowdsourced forecasting of future data
The TADPOLE Challenge compares the performance of algorithms at predicting
the future evolution of individuals at risk of Alzheimer's disease. TADPOLE
Challenge participants train their models and algorithms on historical data
from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. Participants
are then required to make forecasts of three key outcomes for ADNI-3 rollover
participants: clinical diagnosis, ADAS-Cog 13, and total volume of the
ventricles -- which are then compared with future measurements. Strong points
of the challenge are that the test data did not exist at the time of
forecasting (it was acquired afterwards), and that it focuses on the
challenging problem of cohort selection for clinical trials by identifying fast
progressors. The submission phase of TADPOLE was open until 15 November 2017;
since then data has been acquired until April 2019 from 219 subjects with 223
clinical visits and 150 Magnetic Resonance Imaging (MRI) scans, which was used
for the evaluation of the participants' predictions. Thirty-three teams
participated with a total of 92 submissions. No single submission was best at
predicting all three outcomes. For diagnosis prediction, the best forecast
(team Frog), which was based on gradient boosting, obtained a multiclass area
under the receiver-operating curve (MAUC) of 0.931, while for ventricle
prediction the best forecast (team EMC1), which was based on disease
progression modelling and spline regression, obtained mean absolute error of
0.41% of total intracranial volume (ICV). For ADAS-Cog 13, no forecast was
considerably better than the benchmark mixed effects model (BenchmarkME),
provided to participants before the submission deadline. Further analysis can
help understand which input features and algorithms are most suitable for
Alzheimer's disease prediction and for aiding patient stratification in
clinical trials.Comment: 10 pages, 1 figure, 4 tables. arXiv admin note: substantial text
overlap with arXiv:1805.0390
Acute Dietary Nitrate Supplementation Improves Flow Mediated Dilatation of the Superficial Femoral Artery in Healthy Older Males
Aging is often associated with reduced leg blood flow, increased arterial stiffness, and endothelial dysfunction, all of which are related to declining nitric oxide (NO) bioavailability. Flow mediated dilatation (FMD) and passive leg movement (PLM) hyperaemia are two techniques used to measure NO-dependent vascular function. We hypothesised that acute dietary nitrate (NO3â) supplementation would improve NO bioavailability, leg FMD, and PLM hyperaemia. Fifteen healthy older men (69 ± 4 years) attended two experiment sessions and consumed either 140 mL of concentrated beetroot juice (800 mg NO3â) or placebo (NO3â-depleted beetroot juice) in a randomised, double blind, cross-over design study. Plasma nitrite (NO2â) and NO3â, blood pressure (BP), augmentation index (AIx75), pulse wave velocity (PWV), FMD of the superficial femoral artery, and PLM hyperaemia were measured immediately before and 2.5 h after consuming NO3â and placebo. Placebo had no effect but NO3â led to an 8.6-fold increase in plasma NO2â, which was accompanied by an increase in FMD (NO3â: +1.18 ± 0.94% vs. placebo: 0.23 ± 1.13%, p = 0.002), and a reduction in AIx75 (NO3â: â8.7 ± 11.6% vs. placebo: â4.6 ± 5.5%, p = 0.027). PLM hyperaemia, BP, and PWV were unchanged during both trials. This study showed that a dose of dietary NO3â improved NO bioavailability and enhanced endothelial function as measured by femoral artery FMD. These findings provide insight into the specific central and peripheral vascular responses to dietary NO3â supplementation in older adult
Observation of coherent many-body Rabi oscillations
A two-level quantum system coherently driven by a resonant electromagnetic
field oscillates sinusoidally between the two levels at frequency
which is proportional to the field amplitude [1]. This phenomenon, known as the
Rabi oscillation, has been at the heart of atomic, molecular and optical
physics since the seminal work of its namesake and coauthors [2]. Notably, Rabi
oscillations in isolated single atoms or dilute gases form the basis for
metrological applications such as atomic clocks and precision measurements of
physical constants [3]. Both inhomogeneous distribution of coupling strength to
the field and interactions between individual atoms reduce the visibility of
the oscillation and may even suppress it completely. A remarkable
transformation takes place in the limit where only a single excitation can be
present in the sample due to either initial conditions or atomic interactions:
there arises a collective, many-body Rabi oscillation at a frequency
involving all N >> 1 atoms in the sample [4]. This is true even
for inhomogeneous atom-field coupling distributions, where single-atom Rabi
oscillations may be invisible. When one of the two levels is a strongly
interacting Rydberg level, many-body Rabi oscillations emerge as a consequence
of the Rydberg excitation blockade. Lukin and coauthors outlined an approach to
quantum information processing based on this effect [5]. Here we report initial
observations of coherent many-body Rabi oscillations between the ground level
and a Rydberg level using several hundred cold rubidium atoms. The strongly
pronounced oscillations indicate a nearly complete excitation blockade of the
entire mesoscopic ensemble by a single excited atom. The results pave the way
towards quantum computation and simulation using ensembles of atoms
Cosmic ray diffusion near the Bohm limit in the Cassiopeia A supernova remnant
Supernova remnants (SNRs) are believed to be the primary location of the
acceleration of Galactic cosmic rays, via diffusive shock (Fermi) acceleration.
Despite considerable theoretical work the precise details are still unknown, in
part because of the difficulty in directly observing nucleons that are
accelerated to TeV energies in, and affect the structure of, the SNR shocks.
However, for the last ten years, X-ray observatories ASCA, and more recently
Chandra, XMM-Newton, and Suzaku have made it possible to image the synchrotron
emission at keV energies produced by cosmic-ray electrons accelerated in the
SNR shocks. In this article, we describe a spatially-resolved spectroscopic
analysis of Chandra observations of the Galactic SNR Cassiopeia A to map the
cutoff frequencies of electrons accelerated in the forward shock. We set upper
limits on the electron diffusion coefficient and find locations where particles
appear to be accelerated nearly as fast as theoretically possible (the Bohm
limit).Comment: 18 pages, 5 figures. Accepted for publication in Nature Physics (DOI
below), final version available week of August 28, 2006 at
http://www.nature.com/nphy
Catheterization and embolization of a replaced left hepatic artery via the right gastric artery through the anastomosis: a case report
<p>Abstract</p> <p>Introduction</p> <p>Conversion of multiple hepatic arteries into a single vascular supply is a very important technique for repeat hepatic arterial infusion chemotherapy using an implanted port catheter system. Catheterization of a replaced left hepatic artery arising from a left gastric artery using a percutaneous catheter technique is sometimes difficult, despite the recent development of advanced interventional techniques.</p> <p>Case presentation</p> <p>We present a case of a 70-year-old Japanese man with multiple hepatocellular carcinomas in whom the replaced left hepatic artery arising from the left gastric artery needed to be embolized. After several failed procedures, the replaced left hepatic artery was successfully catheterized and embolized with a microcatheter and microcoils via the right gastric artery through the anastomosis.</p> <p>Conclusion</p> <p>A replaced left hepatic artery arising from a left gastric artery can be catheterized via a right gastric artery by using the appropriate microcatheter and microguidewires, and multiple hepatic arteries can be converted into a single supply.</p
Peripheral arterial volume distensibility changes with applied external pressure: significant difference between arteries with different compliance
This study aimed to quantify the different effect of external cuff pressure on arterial volume distensibility between peripheral arteries with different compliance. 30 healthy subjects were studied with the arm at two positions (0° and 45° from the horizontal level) to introduce different compliance of arteries. The electrocardiogram and finger and ear photoplethysmograms were recorded simultaneously under five external cuff pressures (0, 10, 20, 30 and 40âmmHg) on the whole arm to obtain arterial volume distensibility. With the applied external cuff pressures of 10, 20, 30 and 40âmmHg, the overall changes in arterial volume distensibility referred to those without external pressure were 0.010, 0.029, 0.054 and 0.108% per mmHg for the arm at the horizontal level, and 0.026, 0.071, 0.170 and 0.389% per mmHg for the arm at 45° from the horizontal level, confirming the non-linearity between arterial volume distensibility and external pressure. More interestingly, the significant differences in arterial volume distensibility changes were observed between the two arm positions, which were 0.016, 0.043, 0.116 and 0.281% per mmHg (all Pâ<â0.01). Our findings demonstrated that arterial volume distensibility of peripheral arm arteries increased with external pressure, with a greater effect for more compliant arteries
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