1,815 research outputs found
PROSTHETIC LEG DESIGN, FORCE PRODUCTION, AND CURVE SPRINT PERFORMANCE: A PILOT STUDY
We compared the use of a running specific prosthesis (RSP) with a solid or “split-toe“ design by athletes with a leg amputation on sprinting speed and stance-average centripetal ground reaction force (GRF) along a flat 400 m track curve, 200 m track curve, and straightaway. Three athletes with a right transtibial amputation performed maximal effort sprints along the curves (clockwise and counterclockwise) and straightaway of an indoor track using a traditional, solid RSP and an RSP with a split-toe design while we measured 3D GRFs and kinematics. Sprinting speed was significantly faster (p = 0.003) when using the split-toe RSP across curve conditions and directions compared to the solid RSP. However, there was no significant effect of RSP design on stance-average centripetal force (p = 0.180). Sprint speed was similar between RSP designs on the straightaway (p = 0.705)
Influence of anisotropic ion shape, asymmetric valency, and electrolyte concentration on structural and thermodynamic properties of an electric double layer
Grand canonical Monte Carlo simulation results are reported for an electric
double layer modelled by a planar charged hard wall, anisotropic shape cations,
and spherical anions at different electrolyte concentrations and asymmetric
valencies. The cations consist of two tangentially tethered hard spheres of the
same diameter, . One sphere is charged while the other is neutral. Spherical
anions are charged hard spheres of diameter . The ion valency asymmetry 1:2
and 2:1 is considered, with the ions being immersed in a solvent mimicked by a
continuum dielectric medium at standard temperature. The simulations are
carried out for the following electrolyte concentrations: 0.1, 1.0 and 2.0 M.
Profiles of the electrode-ion, electrode-neutral sphere singlet distributions,
the average orientation of dimers, and the mean electrostatic potential are
calculated for a given electrode surface charge, , while the contact
electrode potential and the differential capacitance are presented for varying
electrode charge. With an increasing electrolyte concentration, the shape of
differential capacitance curve changes from that with a minimum surrounded by
maxima into that of a distorted single maximum. For a 2:1 electrolyte, the
maximum is located at a small negative value while for 1:2, at a small
positive value.Comment: 10 pages, 6 figure
Double layer for hard spheres with an off-center charge
Simulations for the density and potential profiles of the ions in the planar
electrical double layer of a model electrolyte or an ionic liquid are reported.
The ions of a real electrolyte or an ionic liquid are usually not spheres; in
ionic liquids, the cations are molecular ions. In the past, this asymmetry has
been modelled by considering spheres that are asymmetric in size and/or valence
(viz., the primitive model) or by dimer cations that are formed by tangentially
touching spheres. In this paper we consider spherical ions that are asymmetric
in size and mimic the asymmetrical shape through an off-center charge that is
located away from the center of the cation spheres, while the anion charge is
at the center of anion spheres. The various singlet density and potential
profiles are compared to (i) the dimer situation, that is, the constituent
spheres of the dimer cation are tangentially tethered, and (ii) the standard
primitive model. The results reveal the double layer structure to be
substantially impacted especially when the cation is the counterion. As well as
being of intrinsic interest, this off-center charge model may be useful for
theories that consider spherical models and introduce the off-center charge as
a perturbation.Comment: 11 pages, 7 figure
Assessment of the Capability of Hog Raisers’ Cooperatives as Conduits of Agricultural Loans in Laguna, Philippines
In view of the importance of credit to agriculture and rural development, it is the objective of this paper to provide an assessment of the capability of hog raisers’ cooperatives as conduits of agricultural loans in Laguna. To attain this objective, the analytical methods namely, (1) Standard Performance Rating Approach, and (2) Pearson and Spearman correlation were employed. The primary data was generated from nine hog raisers’ cooperatives from Laguna. Data from secondary sources was also obtained to further assess the capability of the subject cooperatives from the Cooperative Development Authority Regional Office and hog raisers’ cooperatives. The results of the analyses showed that one out nine cooperatives had a rating of Very Satisfactory, while three and four of them had attained Satisfactory and Fair performance rating, respectively. Only one cooperative had an adjectival rating of Needs Improvement. It is established that the capability of the cooperative as conduit of credit is dependent on its member-borrowers. The result of the correlation analysis revealed that the cooperative’s financial capability indicators namely, assets, profitability, operational strength, solvency, and net institutional capital were correlated with the capability of its member-borrowers to make timely payments. Only net institutional capital had negative association with the member-borrowers’ capability in making timely payments. Thus, the cooperatives are still viable conduits of credit as long as the capability of the member-borrowers is enhanced. This, in effect, led to higher profitability and financial sustainability among hog raisers’ cooperative in Laguna. With this, the study recommended that government should devise and implement a sound credit and technical assistance program that will benefit the hog raisers’ cooperatives. If possible, they should provide training and assistance to enhance cooperatives’ loan absorptive capacity as conduit of credit
Research Notes: Resistance of soybean lines and cultivars to the root-knot nematode, Meloidogyne javanica
In a clayed soil heavy infested with Meloidogyne javanica at Guatapara farm , state of Sao Paulo , 36 soybean cultivars and breeding lines were tested for resistance to this nematode. Plots were constituted of three rows, 3 m long and 0.60 m apart and each plot was bordered on both sides with a row of \u27Davis \u27 cv, the susceptible check. Soybeans were seeded in November, 1979, in a randomized complete block design with eight replications
Sensitivity Comparison of a Self-Standing Porous Silicon Membrane Under Flow-Through and Flow-Over Conditions
An optical sensor based on a self-standing porous silicon (PS) membrane is presented. The sensor was created by electrochemically etching a heavily doped p-type silicon wafer with an organic electrolyte that contained dimethylformamide. After fabrication, a high-current density close to electropolishing was applied in order to allow the detachment from the substrate using a lift-off method. The PS membrane was integrated in a microfluidic cell for sensing purposes, and reflectance spectra were continuously obtained while the target substance was flowed. A comparison of the bulk sensitivity is achieved when flowing through and over the pores is reported. During the experiments, a maximum sensitivity of 770 nm/RIU measured at 1700 nm was achieved. Experimental sensitivity values are in good agreement with the theoretical calculations performed when flowing through the PS membrane, it means that the highest possible sensitivity of that sensor was achieved. In contrast, a drop in the sensitivity of around 25% was observed when flowing over the PS membrane
Supercurrent tunneling between conventional and unconventional superconductors: A Ginzburg-Landau approach
We investigate the Josephson tunneling between a conventional and an unconventional superconductor via a Ginzburg-Landau theory. This approach allows us to write down the general form of the Josephson coupling between the two superconductors, and to see which terms are forbidden or allowed by spatial symmetries. The time-reversal symmetry is also considered. We discuss the current-phase relationships, magnetic, and ac effects if we just include this direct coupling to the unconventional superconductor. In addition we consider the Josephson coupling between two short-coherence-length superconductors, extending the work of Deutscher and Müller (DM) to a finite-current calculation. We find that the critical current is suppressed below the DM value due to the fact that the coupling between the two superconductors across the junction depends on the phase difference and hence the current itself. Finally we investigate the possibility of the proximity effect, in particular the possibility that the conventional-type pairing is induced and hence coexists with the unconventional pairing near the junction. This would give the dominant contribution to the tunneling current if the direct tunneling to the unconventional pairs are suppressed for some reason. We point out that there is no possibility of dissipationless tunneling above the transition temperature of the unconventional superconductor. Even in the case in which the unconventional superconductor is below its transition temperature, we find that, for the possibility of a dissipationless current, it is crucial to have a coupling between the induced s wave and the unconventional superconductor that depends on their phase difference, which allows the conversion of the supercurrent from one type to the other. The behavior of this current, in particular as a function of temperature, is discussed. We also discuss the magnetic and time-dependent effects of the junction in the presence of this proximity effect. We see that, while some of these remain unaffected, some, in particular the time-dependent processes, are affected in a rather nontrivial manner
Human cachexia induces changes in mitochondria, autophagy and apoptosis in the skeletal muscle
Cachexia is a wasting syndrome characterized by the continuous loss of skeletal muscle mass due to imbalance between protein synthesis and degradation, which is related with poor prognosis and compromised quality of life. Dysfunctional mitochondria are associated with lower muscle strength and muscle atrophy in cancer patients, yet poorly described in human cachexia. We herein investigated mitochondrial morphology, autophagy and apoptosis in the skeletal muscle of patients with gastrointestinal cancer-associated cachexia (CC), as compared with a weight-stable cancer group (WSC). CC showed prominent weight loss and increased circulating levels of serum C-reactive protein, lower body mass index and decreased circulating hemoglobin, when compared to WSC. Electron microscopy analysis revealed an increase in intermyofibrillar mitochondrial area in CC, as compared to WSC. Relative gene expression of Fission 1, a protein related to mitochondrial fission, was increased in CC, as compared to WSC. LC3 II, autophagy-related (ATG) 5 and 7 essential proteins for autophagosome formation, presented higher content in the cachectic group. Protein levels of phosphorylated p53 (Ser46), activated caspase 8 (Asp384) and 9 (Asp315) were also increased in the skeletal muscle of CC. Overall, our results demonstrate that human cancer-associated cachexia leads to exacerbated muscle-stress response that may culminate in muscle loss, which is in part due to disruption of mitochondrial morphology, dysfunctional autophagy and increased apoptosis. To the best of our knowledge, this is the first report showing quantitative morphological alterations in skeletal muscle mitochondria in cachectic patients
The effect of phylogeny, environment and morphology on communities of a lianescent clade (Bignonieae-Bignoniaceae) in neotropical biomes
The influence of ecological traits to the distribution and abundance of species is a prevalent issue in biodiversity science. Most studies of plant community assembly have focused on traits related to abiotic aspects or direct interactions among plants, with less attention paid to ignore indirect interactions, as those mediated by pollinators. Here, we assessed the influence of phylogeny, habitat, and floral morphology on ecological community structure in a clade of Neotropical lianas (tribe Bignonieae, Bignoniaceae). Our investigation was guided by the long-standing hypothesis that habitat specialization has promoted speciation in Bignonieae, while competition for shared pollinators influences species co-occurrence within communities. We analyzed a geo-referenced database for 94 local communities occurring across the Neotropics. The effect of floral morphological traits and abiotic variables on species co-occurrence was investigated, taking into account phylogenetic relationships. Habitat filtering seems to be the main process driving community assembly in Bignonieae, with environmental conditions limiting species distributions. Differing specialization to abiotic conditions might have evolved recently, in contrast to the general pattern of phylogenetic clustering found in communities of other diverse regions. We find no evidence that competition for pollinators affects species co-occurrence; instead, pollinator occurrence seems to have acted as an "environmental filter'' in some habitats93FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2006/59916-0CCSD-Missouri Botanical Garden: Elizabeth E. Bascom Fellowships for Latin American Female Botanist
INFLUENCE OF MIDSOLE CONSTRUCTION AND UPPER VAMP DESIGN IN THE PRONATION MOVEMENT WHILE RUNNING
The relationship between the excessive rearfoot pronation and some injuries has been widely described in the literature (Bates, Cavanagh, Nigg, Stacoff). The influence of midsole design and material in the amount of pronation has also been analyzed by different authors. Nevertheless the relative influence of midsole and upper vamp design and their interactions have not been studied enough. The aim of the study presented was to investigate the relative effect of midsole material and thickness as well as upper vamp systems in controlling pronation. Twelve prototypes of running shoes were specially designed and constructed for this study. The prototypes corresponded to a factorial experiment design of the following factors: two midsole thicknesses, three midsole materials, and the presence or absence of an external heel counter and post. The materials selection was based on a previous study of the mechanical characteristics of a group of different Poliurethanes with different densities. The stiffness and energy absorbing capacity of the materials were previously studied by simulating impact loads of running by means of a dynamic testing machine. The external heel counter and post was selected as a representative of a very effective rearfoot control feature based in a previous study where it appeared to be the most effective system of the studied (heel counters, bondings for the lacing and internal posts). Three runners participated in the study. All of them were rearfoot strikers and hiperpronators. The experiences consisted of filming three right foot supports with two high speed cameras. Velocity of running was fixed at 12.8 Km per hour while velocity of filmation was fixed at 150 images per second. After digitizing the images obtained, a three dimensional study of the rearfoot movement was done. The results obtained can be summarized as follows: - Midsole thickness, midsole material and the presence of the heel counter showed significant influence on maximum rearfoot pronation with the most important being the midsole material in the range of variations of the study. - The material presenting low rigidity and low shock absorbing capacity was the one that showed higher pronation angles. - Higher pronation angles were found for the thicker midsoles. - The heel counter and post was found to have less influence on maximum pronation angles than the midsole thickness and material
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