926 research outputs found
Feeding and metabolism of the jellyfish Pelagia noctiluca (scyphomedusae, semaeostomae)
International audienc
Application of High Performance Photoinitiating Systems for Holographic Grating Recording
In this chapter, a compilation of different systems able to photogenerate active radicals toward polymerization reaction( type I, type II and three component photoinitiating systems) for application in holographic grating recording when associated to monomers is reviewed. In particular, the visible curable system is associated to fluorinated acrylate monomers formulation for creation of transmission gratings. The PIS efficiencies are presented in term of diffraction grating yields and compared to photopolymerization experiments. The special case of photocyclic initiating systems is described in details, its influence on the grating built up being discussed on the basis of selected mixtures using visible dyes, electron donors (e.g. amines), electron acceptors (e.g. iodonium salts) or hydrogen donors as coinitiators. The role of the photochemical properties of dye on the performance of the holographic recording material is investigated through time resolved and steady state spectroscopic studies of the PIS (e.g. nanosecond laser flash photolysis), to highlight the photochemistry underlying active radicals photogeneration. In order to get more insight into the hologram formation, grating formation curves were compared to those of monomer to polymer conversion obtained by real time Fourier transform infrared spectroscopy (RTFTIR). This work outlines the importance of the coupling between the photoinitiating system (i.e. the photochemical reactions) and the holographic resin
Small-scale distribution of macroplankton and micronekton in the Ligurian Sea (Mediterranean Sea) as observed from the manned submersible Cyana
International audienc
Mitochondrial involvement in sarcopenia
Sarcopenia lowers the qualityâofâlife for millions of people across the world, as accelerated loss of skeletal muscle mass and function contributes to both ageâ and diseaseârelated frailty. Physical activity remains the only proven therapy for sarcopenia to date, but alternatives are much sought after to manage this progressive muscle disorder in individuals who are unable to exercise. Mitochondria have been widely implicated in the etiology of sarcopenia and are increasingly suggested as attractive therapeutic targets to help restore the perturbed balance between protein synthesis and breakdown that underpins skeletal muscle atrophy. Reviewing current literature, we note that mitochondrial bioenergetic changes in sarcopenia are generally interpreted as intrinsic dysfunction that renders muscle cells incapable of making sufficient ATP to fuel protein synthesis. Based on the reported mitochondrial effects of therapeutic interventions, however, we argue that the observed bioenergetic changes may instead reflect an adaptation to pathologically decreased energy expenditure in sarcopenic muscle. Discrimination between these mechanistic possibilities will be crucial for improving the management of sarcopenia
The Dynamics of Silica Melts under High Pressure: Mode-Coupling Theory Results
The high-pressure dynamics of a computer-modeled silica melt is studied in
the framework of the mode-coupling theory of the glass transition (MCT) using
static-structure input from molecular-dynamics (MD) computer simulation. The
theory reproduces the experimentally known viscosity minimum (diffusivity
maximum) as a function of density or pressure and explains it in terms of a
corresponding minimum in its critical temperature. This minimum arises from a
gradual change in the equilibrium static structure which shifts from being
dominated by tetrahedral ordering to showing the cageing known from
high-density liquids. The theory is in qualitative agreement with computer
simulation results.Comment: Presented at ESF EW Glassy Liquids under Pressure, to be published in
Journal of Physic
An evaluation of dexterity and cutaneous sensibility tests for use with medical gloves
© 2015 Institution of Mechanical Engineers.The ability of selected dexterity and cutaneous sensibility tests to measure the effect of medical glove properties (material, fit, and number of layers) on manual performance was analyzed. Manual performance testing of gloves to-date has focused on thicker gloves where the effects are more obvious. However, clinicians have reported dissatisfaction with some medical gloves and a perceived detriment to performance of new materials compared to latex. Three tests (Purdue Pegboard Test, Crawford Small Parts Dexterity Test, and Semmes-Weinstein Monofilaments) were performed by 18 subjects in five hand conditions (ungloved; best-fitting, loose-fitting and a double layer of latex examination gloves; best-fitting vinyl gloves). Tests were performed in the ungloved condition first, and the order of the gloved tests was randomized. Learning behavior was also measured. The Purdue test showed a significant effect of hand condition, but no differences between latex and vinyl. No significant effect of hand condition was found in the Crawford "Pins and Collars" test, but the "Screws" test showed promising discrimination between glove types. The Monofilaments test showed a significant effect of hand condition on cutaneous sensibility, particularly a reduction when "double-gloving," but no significant differences between glove types. Existing tests show some ability to measure the effect of gloves and their properties on manual performance but are not comprehensive and require further validation. In order to fully describe the effects of medical gloves on manual performance, further tests should be designed with greater resolution and that better replicate clinical manual tasks
Acute bioenergetic insulin sensitivity of skeletal muscle cells: ATP-demand-provoked glycolysis contributes to stimulation of ATP supply
Skeletal muscle takes up glucose in an insulin-sensitive manner and is thus important for the maintenance of blood glucose homeostasis. Insulin resistance during development of type 2 diabetes is associated with decreased ATP synthesis, but the causality of this association is controversial. In this paper, we report real-time oxygen uptake and medium acidification data that we use to quantify acute insulin effects on intracellular ATP supply and ATP demand in rat and human skeletal muscle cells. We demonstrate that insulin increases overall cellular ATP supply by stimulating the rate of glycolytic ATP synthesis. Stimulation is immediate and achieved directly by increased glycolytic capacity, and indirectly by elevated ATP demand from protein synthesis. Raised glycolytic capacity does not result from augmented glucose uptake. Notably, insulin-sensitive glucose uptake is increased synergistically by nitrite. While nitrite has a similar stimulatory effect on glycolytic ATP supply as insulin, it does not amplify insulin stimulation. These data highlight the multifarious nature of acute bioenergetic insulin sensitivity of skeletal muscle cells, and are thus important for the interpretation of changes in energy metabolism that are seen in insulin-resistant muscle
A finite element model for predicting impact-induced damage to a skin simulant
A finite element model was developed for assessing the efficacy of rugby body padding in reducing the risk of sustaining cuts and abrasions. The model was developed to predict the onset of damage to a soft tissue simulant from concentrated impact loading (i.e., stud impact) and compared against a corresponding experiment. The damage modelling techniques involved defining an element deletion criterion, whereby those on the surface of the surrogate were deleted if their maximum principal stress reached a predefined value. Candidate maximum principal stress values for element deletion criteria were identified independently from puncture test simulations on the soft tissue simulant. Experimental impacts with a stud were carried out at three energies (2, 4 and 6 J), at three angular orientations (0°, 15° and 30°) and compared to corresponding simulations. Suitable maximum principal stress values for element deletion criteria settings were first identified for the 4 J impact, selecting the candidates that best matched the experimental results. The same element deletion settings were then applied in simulations at 2 and 6 J and the validity of the model was further assessed (differenceâ<â15% for the force at tear andâ<â30% for time to tear). The damage modelling techniques presented here could be applied to other skin simulants to assess the onset of skin injuries and the ability of padding to prevent them
Bond breaking in vibrationally excited methane on transition metal catalysts
The role of vibrational excitation of a single mode in the scattering of
methane is studied by wave packet simulations of oriented CH4 and CD4 molecules
from a flat surface. All nine internal vibrations are included. In the
translational energy range from 32 up to 128 kJ/mol we find that initial
vibrational excitations enhance the transfer of translational energy towards
vibrational energy and increase the accessibility of the entrance channel for
dissociation. Our simulations predict that initial vibrational excitations of
the asymmetrical stretch (nu_3) and especially the symmetrical stretch (nu_1)
modes will give the highest enhancement of the dissociation probability of
methane.Comment: 4 pages REVTeX, 2 figures (eps), to be published in Phys. Rev. B.
(See also arXiv:physics.chem-ph/0003031). Journal version at
http://publish.aps.org/abstract/PRB/v61/p1565
Deployment characterization of a floatable tidal energy converter on a tidal channel, Ria Formosa, Portugal
This paper presents the results of a pilot experiment with an existing tidal energy converter (TEC),
Evopod 1 kW floatable prototype, in a real test case scenario (Faro Channel, Ria Formosa, Portugal). A
baseline marine geophysical, hydrodynamic and ecological study based on the experience collected on
the test site is presented. The collected data was used to validate a hydro-morphodynamic model,
allowing the selection of the installation area based on both operational and environmental constraints.
Operational results related to the description of power generation capacity, energy capture area and
proportion of energy flux are presented and discussed, including the failures occurring during the
experimental setup. The data is now available to the scientific community and to TEC industry developers,
enhancing the operational knowledge of TEC technology concerning efficiency, environmental
effects, and interactions (i.e. device/environment). The results can be used by developers on the licensing
process, on overcoming the commercial deployment barriers, on offering extra assurance and confidence
to investors, who traditionally have seen environmental concerns as a barrier, and on providing the
foundations whereupon similar deployment areas can be considered around the world for marine tidal
energy extraction.Acknowledgements
The paper is a contribution to the SCORE project, funded by the
Portuguese Foundation for Science and Technology (FCT e PTDC/
AAG-TEC/1710/2014). Andre Pacheco was supported by the Portu-
guese Foundation for Science and Technology under the Portuguese
Researchers' Programme 2014 entitled âExploring new concepts for
extracting energy from tidesâ (IF/00286/2014/CP1234). Eduardo GGorbena has received funding for the OpTiCA project from the ~
Marie SkĆodowska-Curie Actions of the European Union's H2020-
MSCA-IF-EF-RI-2016/under REA grant agreement n [748747]. The
authors would like to thank to the Portuguese Maritime Authorities
and Sofareia SA for their help on the deployment.info:eu-repo/semantics/publishedVersio
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