920 research outputs found
Correlational analysis between joint-level kinetics of countermovement jumps and weightlifting derivatives
The purpose of this study was to investigate the mechanical similarity between net joint moments (NJM) of the countermovement jump (CMJ) and the hang power clean (HPC) and jump shrug (JS). Twelve male Lacrosse players performed three maximal effort CMJs and three repetitions of the HPC and JS at 30%, 50%, and 70% of their HPC one repetition maximum (1-RM). Ground reaction forces and motion capture data were used to calculate the NJM of the hip, knee, and ankle joints during each exercise. Statistical comparison of the peak NJM indicated that NJM during the HPC and JS across all loads were equal to or greater than the NJM during the CMJ (all p < 0.025). In addition, correlation analyses indicated that CMJ hip NJM were associated (all p < 0.025) with HPC hip NJM at 30% and 70% (r = 0.611-0.822) and JS hip NJM at 50% and 70% (r = 0.674-0.739), whereas CMJ knee NJM were associated with HPC knee NJM at 70% (r = 0.638) and JS knee NJM at 50% and 70% (r = 0.664-0.732). Further, CMJ ankle NJM were associated with HPC ankle NJM at 30% and 50% (r = 0.615-0.697) and JS ankle NJM at 30%, 50%, and 70% (r = 0.735-0.824). Lastly, knee and ankle NJM during the JS were greater than during the HPC at 30% and 50% of 1-RM (all p < 0.017). The degree of mechanical similarity between the CMJ and the HPC and JS is dependent on the respective load and joint. [Abstract copyright: © Journal of Sports Science and Medicine.
A method to estimate the significance of coincident gravitational-wave observations from compact binary coalescence
Coalescing compact binary systems consisting of neutron stars and/or black
holes should be detectable with upcoming advanced gravitational-wave detectors
such as LIGO, Virgo, GEO and {KAGRA}. Gravitational-wave experiments to date
have been riddled with non-Gaussian, non-stationary noise that makes it
challenging to ascertain the significance of an event. A popular method to
estimate significance is to time shift the events collected between detectors
in order to establish a false coincidence rate. Here we propose a method for
estimating the false alarm probability of events using variables commonly
available to search candidates that does not rely on explicitly time shifting
the events while still capturing the non-Gaussianity of the data. We present a
method for establishing a statistical detection of events in the case where
several silver-plated (3--5) events exist but not necessarily any
gold-plated () events. We use LIGO data and a simulated, realistic,
blind signal population to test our method
A Finite Element Computer Model of the Captive Column
This report describes the computerized mathematical modeling of a composite structural assemblage referred to as a captive column . The captive column is a potentially useful structural member (beam, column, or torsion member) which exhibits a high strength-to-weight ratio. The captive column consists of three basic components: a lightweight core section, the principal load bearing elements referred to as caps, and a filamentous wrap, helically wound around the other two members. Together the three elements act as an integral unit and can be constructed in mul- tigeometrical cross sections and diverse lengths.
A linearly elastic finite element computer model was developed to analyze the structural behavior of captive columns under static bending loads. On this model the captive column core ribs were represented by a combination of orthotropic plane stress elements and beam elements. Beam elements were also utilized for modeling the caps, while truss elements represented the wrap strands. Typical computer model sizes of the columns included 60 nodes and 213 elements for the triangular cross section and 105 nodes and 404 elements for the square cross section.
A total of ten experimental test specimens, all 28 inches long, were constructed for the purpose of verifying the computer model. The specimens were loaded as simply supported beams while the applied load, deflections under the load, and core strain 3.5 inches on either side of the load were recorded. These experimental results were then compared with the computer model results. These results are as follows.
The computer model deflections at the midspan of the column, under a concentrated load, were 10 to 12 percent less than the actual experimentally measured deflections. Furthermore, for the captive columns with steel caps, the computer model core stresses, at a point 3.5 inches on either side of the midspan load, differ by no more than 20 percent from the experimentally measured core stresses. For the captive columns with fiberglass caps, the computer model cores stresses differ by 95 percent and 74 percent for the algebraically smallest principal stress and less than 8 percent for the other, larger, principal stress. Principal directions of the two dimensional stress element differed by no more than 11 percent for the steel capped captive column and from 2 to 28 percent for the fiberglass capped captive column.
In conclusion, initial verification has been obtained for a finite element model of the captive column structural composite. Additionally, preliminary design procedures have been outlined for specifying the cap, wrap, and core of the captive column for specific loading applications
Проблемы теневой экономики в Украине
Brain inflammation plays a central role in multiple sclerosis (MS). Besides lymphocytes, the astroglia and microglia mainly contribute to the cellular composition of the inflammatory infiltrate in MS lesions. Several studies were able to demonstrate that cortical lesions are characterized by lower levels of inflammatory cells among activated microglia/macrophages. The underlying mechanisms for this difference, however, remain to be clarified. In the current study, we compared the kinetics and extent of microglia and astrocyte activation during early and late cuprizone-induced demyelination in the white matter tract corpus callosum and the telencephalic gray matter. Cellular parameters were related to the expression profiles of the chemokines Ccl2 and Ccl3. We are clearly able to demonstrate that both regions are characterized by early oligodendrocyte stress/apoptosis with concomitant microglia activation and delayed astrocytosis. The extent of microgliosis/astrocytosis appeared to be greater in the subcortical white matter tract corpus callosum compared to the gray matter cortex region. The same holds true for the expression of the key chemokines Ccl2 and Ccl3. The current study defines a model to study early microglia activation and to investigate differences in the neuroinflammatory response of white vs. gray matter
Changes in Physical Function Following 4-Weeks of Neuromuscular Electrical Stimulation Training in Older Adults
Sarcopenia, the age-related loss of muscle mass and strength, can result in a decline in physical function. Neuromuscular electrical stimulation (NMES) has been shown to induce muscular adaptations that have the potential to translate to functional improvements; however, little is known regarding functional adaptations pre-post short-term NMES training, especially in older adults. PURPOSE: The aim of this study was to determine NMES-induced changes in lower extremity physical function following 4 weeks of an NMES training intervention of the quadriceps muscle in older adults. METHODS: Seventeen healthy, older adults (68.8 ± 1.8 years old) were divided into two groups: NMES (n = 12) and SHAM (n = 5). The NMES group underwent 12, 40-minute NMES training sessions to the quadriceps muscles on each leg 3x/week over 4 weeks, with the stimulation intensity adjusted every 5 minutes, as needed, to achieve a 15% target torque of each participant’s maximal voluntary contraction (MVC). The stimulation parameters consisted of a 60 Hz stimulation frequency and a duty cycle of 10s on and 15s off. The SHAM group was blinded and did not receive any treatment. The following functional assessments were measured before and after the 4-week training period: Timed Up and Go (TUG), 5x Sit-to-Stand (5XSTS), Stair Climb (SC), and 6-Minute Walk Test (6MWT). Repeated-measures ANOVAs were used to determine changes in TUG, 5XSTS, SC, and 6MWT assessments pre-post NMES training and data are reported as mean ± SE. Statistical significance was set at P \u3c 0.05. RESULTS: NMES training significantly improved TUG (NMES: 8.81 ± 0.54s vs. 7.67 ± 0.39s; P = 0.002; SHAM: 10.60 ± 2.41 vs. 10.93 ± 3.01s; P = 0.652; pre- and post-training, respectively) and SC (NMES: 4.03 ± 0.20s vs. 3.76 ± 0.16s; P = 0.023; SHAM: 6.53 ± 2.11 vs. 6.0 ± 1.78s; P = 0.215; pre- and post-training, respectively); however, 5XSTS (NMES: 9.70 ± 0.75 vs. 8.83 ± 0.72; P \u3e 0.05; SHAM: 14.34 ± 3.64 vs. 13.28 ± 3.89; P \u3e 0.05; pre- and post-training, respectively) and 6MWT (NMES: 610.10 ± 22.68 vs. 623.74 ± 14.73; P \u3e 0.05; SHAM: 533.43 ± 82.44 vs. 587.81 ± 80.52; P \u3e 0.05; pre- and post-training, respectively) did not change following the NMES intervention. CONCLUSION: Improvements in TUG and SC following 4 weeks of NMES training demonstrate augmented lower body physical function, suggesting that short-term NMES training programs may induce neuromuscular adaptations that contribute to these early improvements in physical function in older adults
Characterization of immune response to neurofilament light in experimental autoimmune encephalomyelitis
PMCID: PMC3856490This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.PMCID: PMC385649
Parameter estimation on gravitational waves from neutron-star binaries with spinning components
Inspiraling binary neutron stars are expected to be one of the most
significant sources of gravitational-wave signals for the new generation of
advanced ground-based detectors. We investigate how well we could hope to
measure properties of these binaries using the Advanced LIGO detectors, which
began operation in September 2015. We study an astrophysically motivated
population of sources (binary components with masses
-- and spins of less than )
using the full LIGO analysis pipeline. While this simulated population covers
the observed range of potential binary neutron-star sources, we do not exclude
the possibility of sources with parameters outside these ranges; given the
existing uncertainty in distributions of mass and spin, it is critical that
analyses account for the full range of possible mass and spin configurations.
We find that conservative prior assumptions on neutron-star mass and spin lead
to average fractional uncertainties in component masses of , with
little constraint on spins (the median upper limit on the spin of the
more massive component is ). Stronger prior constraints on
neutron-star spins can further constrain mass estimates, but only marginally.
However, we find that the sky position and luminosity distance for these
sources are not influenced by the inclusion of spin; therefore, if LIGO detects
a low-spin population of BNS sources, less computationally expensive results
calculated neglecting spin will be sufficient for guiding electromagnetic
follow-up.Comment: 10 pages, 9 figure
The First Two Years of Electromagnetic Follow-Up with Advanced LIGO and Virgo
We anticipate the first direct detections of gravitational waves (GWs) with
Advanced LIGO and Virgo later this decade. Though this groundbreaking technical
achievement will be its own reward, a still greater prize could be observations
of compact binary mergers in both gravitational and electromagnetic channels
simultaneously. During Advanced LIGO and Virgo's first two years of operation,
2015 through 2016, we expect the global GW detector array to improve in
sensitivity and livetime and expand from two to three detectors. We model the
detection rate and the sky localization accuracy for binary neutron star (BNS)
mergers across this transition. We have analyzed a large, astrophysically
motivated source population using real-time detection and sky localization
codes and higher-latency parameter estimation codes that have been expressly
built for operation in the Advanced LIGO/Virgo era. We show that for most BNS
events the rapid sky localization, available about a minute after a detection,
is as accurate as the full parameter estimation. We demonstrate that Advanced
Virgo will play an important role in sky localization, even though it is
anticipated to come online with only one-third as much sensitivity as the
Advanced LIGO detectors. We find that the median 90% confidence region shrinks
from ~500 square degrees in 2015 to ~200 square degrees in 2016. A few distinct
scenarios for the first LIGO/Virgo detections emerge from our simulations.Comment: 17 pages, 11 figures, 5 tables. For accompanying data, see
http://www.ligo.org/scientists/first2year
N-Acetylcysteine as modulator of the essential trace elements copper and zinc
N-acetylcysteine (NAC) is a frequently prescribed drug and known for its metal chelating capability. However, to date it is not well characterized whether NAC intake affects the homeostasis of essential trace elements. As a precursor of glutathione (GSH), NAC also has the potential to modulate the cellular redox homeostasis. Thus, we aimed to analyze effects of acute and chronic NAC treatment on the homeostasis of copper (Cu) and zinc (Zn) and on the activity of the redox-sensitive transcription factor Nrf2. Cells were exposed to 1 mM NAC and were co-treated with 50 µM Cu or Zn. We showed that NAC treatment reduced the cellular concentration of Zn and Cu. In addition, NAC inhibited the Zn-induced Nrf2 activation and limited the concomitant upregulation of cellular GSH concentrations. In contrast, mice chronically received NAC via drinking water (1 g NAC/100 mL). Cu and Zn concentrations were decreased in liver and spleen. In the duodenum, NQO1, TXNRD, and SOD activities were upregulated by NAC. All of them can be induced by Nrf2, thus indicating a putative Nrf2 activation. Overall, NAC modulates the homeostasis of Cu and Zn both in vitro and in vivo and accordingly affects the cellular redox balance
Determination of surface properties of various substrates using TiO2 nanorod coatings with tunable characteristics
We present a novel approach to cover different substrates with thin light-sensitive layers that consist of organic-capped TiO2 nanorods (NRs). Such NR-based coatings exhibit an increasing initial hydrophobicity with increasing NR length, and they demonstrate a surface transition from this highly hydrophobic state to a highly hydrophilic one under selective UV–laser irradiation. This behaviour is reversed under long dark storage. Infrared spectroscopy measurements reveal that light-driven wettability changes are accompanied by a progressive hydroxylation of the TiO2 surface. The surfactant molecules that cover the NRs do not appear to suffer for any significant photocatalytic degradation
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