6,304 research outputs found
FORCE AND ELECTROMYOGRAPHIC (EMG) RELATIONSHIPS OF LEG EXTENSORS DURING ERGOMETER CONTRACTIONS
'The purpose of this study was to examine the force/EMG relationship during dynamic muscle contractions. Three ergometers (isokinetic dynamometer, adapted leg-only ergometer, standard rowing ergometer) were modified with strain gauges and potentiometers to measure force and displacement. Surface electrodes were used to record EMG of rectus femoris (RF) and vastus lateralis (VL) muscles. Trained rowers (n=ll) performed leg extensions at randomly selected target forces under each condition. There was a strong positive linear correlation between force and EMG amplitude (RF, VL) under constant velocity conditions (r2=.866, .871). Although diminished in strength, this relationship was maintained under leg-only and standard ergometer conditions. The findings support the use of force/EMG analysis during rowing performance
Propulsion simulator for magnetically-suspended wind tunnel models
The objective of phase two of a current investigation sponsored by NASA Langley Research Center is to demonstrate the measurement of aerodynamic forces/moments, including the effects of exhaust gases, in magnetic suspension and balance system (MSBS) wind tunnels. Two propulsion simulator models are being developed: a small-scale and a large-scale unit, both employing compressed, liquified carbon dioxide as propellant. The small-scale unit was designed, fabricated, and statically-tested at Physical Sciences Inc. (PSI). The large-scale simulator is currently in the preliminary design stage. The small-scale simulator design/development is presented, and the data from its static firing on a thrust stand are discussed. The analysis of this data provides important information for the design of the large-scale unit. A description of the preliminary design of the device is also presented
Living arrangements in Sub-Saharan Africa between ethnicity and modernization
In Sub-Saharan Africa the phenomenology of living arrangements is of great interest owing to the extraordinary diversification and complexity of the traditional family patterns. In particular, the predominance of the enlarged family over the biological family is a feature that traditionally distinguishes the conception and the organization of the Sub-Saharan African family. It is a debatable question whether this feature is everlasting or it evolves with the deep economic and social changes occurring in Sub-Saharan African countries. We aim to analyse the living arrangements in several Sub-Saharan countries and in their main ethnic groups, attempting to enlighten the interaction between “modernization” and cultural heritage in shaping family patterns. A temporal perspective has been adopted, as well as the ethnic and rural/urban differentials. The analyses consider ten countries in different geographical areas of Sub-Saharan Africa, where at least two waves of Demographic and Health Surveys were carried out between 1990 and 2013. To detail the analyses, we also consider the most representative ethnic groups for each country (in all 38 ethnic groups). After recalling the theoretical background and present preliminary descriptive findings, the classical procedure of factor analysis is used with the principal components method, followed by an hierarchical classification analysis. Our results show that it is not possible to propose general models for the great traditional geographical areas in Africa. The trends and the rural-urban differentials are not exhaustively explained by modernization factors. The results are in line with the literature outcomes that supported the process of growing variability of living arrangements and the increase of new family models, rather than the existence of a convergence process on a single nuclear family pattern. Ethnic background is confirmed as a valid interpretative key, necessary to understand the cultural substrate in which the evolutive factors brought by globalization act
The Seigniory of Sark and the Duchy Of Cornwall: Similarities and Differences Including Observations on the Isles of Scilly
A unified and robust mathematical model for compressible and incompressible linear elasticity can be obtained by rephrasing the Herrmann formulation within the Hellinger-Reissner principle. This quasi-optimally converging extension of PEERS (Plane Elasticity Element with Reduced Symmetry) is called Dual-Mixed Hybrid formulation (DMH). Explicit residual-based a posteriori error estimates for DMH are introduced and are mathematically shown to be locking-free, reliable, and efficient. The estimator serves as a refinement indicator in an adaptive algorithm for effective automatic mesh generation. Numerical evidence supports that the adaptive scheme leads to optimal convergence for Lam\ue9 and Stokes benchmark problems with singularities
Women's choices in non-invasive prenatal testing for aneuploidy screening: results from a single centre prior to introduction in England
OBJECTIVE: To evaluate patient choices and uptake of non-invasive prenatal testing (NIPT) for aneuploidy screening offered in a contingency model as part of routine care. METHOD: We retrospectively reviewed data for all women with a singleton pregnancy attending for routine first trimester screening over an 18-month period. Women with a 'high-chance' of trisomy 21, 18 or 13 (≥1:150) were offered the choice of no further testing, NIPT or invasive testing, in line with the screening pathway recommended by the UK National Screening Committee. RESULTS: Of 9342 women attending for a first trimester ultrasound scan, 7939 women were included in this study. Of these, 352 had a high-chance screening result for trisomy 21, and 291 (82.7%) opted for NIPT. The proportion of women opting for NIPT decreased as the chance of trisomy 21 increased: uptake was 93.2%, 90.0%, 77.1% and 47.2% for women with a chance of 1:100-150, 1:50-99, 1:10-49 and >1:10, respectively. 516 women (5.5%) accessed primary NIPT screening in the private sector, and 638 women (6.8%) declined any aneuploidy screening or testing. CONCLUSION: Implementation of NIPT testing in a contingency model has a high uptake in a non-research National Health Service setting; the rate of uptake is related to the combined test risk result
ELBOW FLEXOR MUSCLE FUNCTION AND UPPER ARM GIRTH FOLLOWING CONCURRENT STRENGTH AND ENDURANCE TRAINING IN NON RESISTANCETRAINED FEMALES
The study investigated the effects of eight weeks of concurrent muscular strength and endurance resistance training of the non-dominant elbow flexors on muscular strength, endurance, and upper arm girths of previously non resistance-trained females. Subjects (n=12) were assigned to one of 3 training groups. These groups were Strength (S), Endurance (E), or Combined (C) with pre and post-training tests for arm girths, 1 RM preacher curl, maximal isometric torque, peak isokinetic torque at velocities of 30 and 90" s-', and total work during 25 continuous repetitions at 90"s.'. Significant increases in prepost strength and endurance occurred in both C and S groups, but not E, in the absence of any change in arm girth. Furthermore, C training produced equivalent gains in strength and endurance to the S and E groups, respectively
Disassembly of interchromatin granule clusters alters the coordination of transcription and pre-mRNA splicing
To examine the involvement of interchromatin granule clusters (IGCs) in transcription and pre-mRNA splicing in mammalian cell nuclei, the serine-arginine (SR) protein kinase cdc2-like kinase (Clk)/STY was used as a tool to manipulate IGC integrity in vivo. Both immunofluorescence and transmission electron microscopy analyses of cells overexpressing Clk/STY indicate that IGC components are completely redistributed to a diffuse nuclear localization, leaving no residual structure. Conversely, overexpression of a catalytically inactive mutant, Clk/STY(K190R), causes retention of hypophosphorylated SR proteins in nuclear speckles. Our data suggest that the protein-protein interactions responsible for the clustering of interchromatin granules are disrupted when SR proteins are hyperphosphorylated and stabilized when SR proteins are hypophosphorylated. Interestingly, cells without intact IGCs continue to synthesize nascent transcripts. However, both the accumulation of splicing factors at sites of pre-mRNA synthesis as well as pre-mRNA splicing are dramatically reduced, demonstrating that IGC disassembly perturbs coordination between transcription and pre-mRNA splicing in mammalian cell nuclei
Molecules in the transition disk orbiting T Cha
We seek to establish the presence and properties of gas in the circumstellar
disk orbiting T Cha, a nearby (d~110 pc), relatively evolved (age ~5-7 Myr) yet
actively accreting 1.5 Msun T Tauri star. We used the APEX 12 m radiotelescope
to search for submillimeter molecular emission from the T Cha disk, and we
reanalyzed archival XMM-Newton spectroscopy of T Cha to ascertain the
intervening absorption due to disk gas along the line of sight to the star
(N_H). We detected submillimeter rotational transitions of 12CO, 13CO, HCN, CN
and HCO+ from the T Cha disk. The 12CO line appears to display a double-peaked
line profile indicative of Keplerian rotation. Analysis of the CO emission line
data indicates that the disk around T Cha has a mass (M_disk,H_2 = 80 M_earth)
similar to, but more compact (R_disk, CO~80 AU) than, other nearby, evolved
molecular disks (e.g. V4046 Sgr, TW Hya, MP Mus) in which cold molecular gas
has been previously detected. The HCO+/13CO and HCN/13CO, line ratios measured
for T Cha appear similar to those of other evolved circumstellar disks (i.e. TW
Hya and V4046 Sgr), while the CN/13CO ratio appears somewhat weaker. Analysis
of the XMM-Newton data shows that the atomic absorption toward T Cha is
1-2 orders of magnitude larger than toward the other nearby T Tauri with
evolved disks. Furthermore, the ratio between atomic absorption and optical
extinction N_H/A_V toward T Cha is higher than the typical value observed for
the interstellar medium and young stellar objects in the Orion Nebula Cluster.
This may suggest that the fraction of metals in the disk gas is higher than in
the interstellar medium. Our results confirm that pre-main sequence stars older
than ~5 Myr, when accreting, retain cold molecular disks, and that those
relatively evolved disks display similar physical and chemical properties.Comment: Accepted for publication on A&
A micro-macro homogenization for modeling the masonry out-of-plane response
This study introduces a finite element model based on a two-scale beam-to-beam homogenization procedure for the analysis of masonry structural members undergoing prevailing axial and bending stress states. The model is developed considering the periodic repetition of bricks and mortar joints in regular stack bond arrangement and assuming a linear elastic behavior for the former and a nonlinear response for the latter. At the microscopic heterogeneous scale, the behavior of a Unit Cell (UC) made of a single brick and mortar layer is described through an equivalent Timoshenko beam representation, where a nonlocal damage formulation with friction plasticity governs the mortar nonlinear constitutive relationship. Basing on a semi-analytical approach, the microscopic quantities are, then, homogenized to define an equivalent beam model at the macroscopic scale. The proposed finite element model is implemented in standard numerical codes to investigate the response of typical one-dimensional (1D) masonry elements. This study shows the numerical simulation of two experimental tests: a rectangular wallette under out-of-plane bending and a circular arch under vertical forces. The results obtained for the proposed model are compared with those resulting from micromechanical approaches and the experimental outcomes
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