2,997 research outputs found

    Interconnect resistance of photovoltaic submodules

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    Small area amorphous silicon solar cells generally have higher efficiencies than large interconnected submodules. Among the reasons for the differences in performance are the lack of large area uniformity, the effect of nonzero tin oxide sheet resistance, and possibly pinholes in the various layers. Another and usually small effect that can contribute to reduced performance of interconnected cells is the resistance of the interconnection i.e., the series resistance introduced by the metal to tin oxide contact through silicon. Proper processing problems to avoid poor contacts are discussed

    Role of peripheral quantitative computed tomography in identifying disuse osteoporosis in paraplegia

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    Objective: Disuse osteoporosis is a major long-term health consequence of spinal cord injury (SCI) that still needs to be addressed. Its management in SCI should begin with accurate diagnosis, followed by targeted treatments in the most vulnerable subgroups. We present data quantifying disuse osteoporosis in a cross-section of the Scottish paraplegic population to identify subgroups with lowest bone mineral density (BMD). Materials and Methods: Forty-seven people with chronic SCI at levels T2-L2 were scanned using peripheral Quantitative Computed Tomography (pQCT) at four tibial sites and two femoral sites, at the Queen Elizabeth National Spinal Injuries Unit, Glasgow (U.K.). At the distal epiphyses, trabecular BMD (BMDtrab), total BMD, total bone cross-sectional area (CSA), and bone mineral content (BMC) were determined. In the diaphyses, cortical BMD, total bone CSA, cortical CSA, and BMC were calculated. Bone, muscle and fat CSAs were estimated in the lower leg and thigh. Results: BMDtrab decreased exponentially with time since injury, at different rates in the tibia and femur. At most sites, female paraplegics had significantly lower BMC, total bone CSA and muscle CSA than male paraplegics. Subjects with lumbar SCI tended to have lower bone values and smaller muscle CSAs than in thoracic SCI. Conclusion: At the distal epiphyses of the tibia and femur, there is generally a rapid and extensive reduction in BMDtrab after SCI. Female subjects, and those with lumbar SCI, tend to have lower bone values than males or those with thoracic SCI, respectively. Keywords: Bone loss, osteoporosis, paraplegia, peripheral Quantitative Computed Tomography, spinal cord injur

    Effect of detraining on bone and muscle tissue in subjects with chronic spinal cord injury after a period of electrically-stimulated cycling: a small cohort study

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    Objective: To investigate adaptive changes in bone and muscle parameters in the paralysed limbs after de-training or reduced functional electrical stimulation (FES) induced cycling following high-volume FES-cycling in chronic spinal cord injury (SCI). Subjects: Five subjects with motor-sensory complete SCI (age 38.6 years, lesion duration 11.4 years) were included. Four subjects stopped FES-cycling completely after the training phase whereas one continued reduced FES-cycling (2-3 times/week, for 30min). Methods: Bone and muscle parameters were assessed in the legs using peripheral quantitative computed tomography at six and twelve months after cessation of high-volume FES-cycling. Results: Gains achieved in the distal femur by high-volume FES-cycling were partly maintained at one year of detraining: 73.0% in trabecular bone mineral density (BMD), 63.8% in total BMD, 59.4% in bone mineral content and 22.1% in muscle cross-sectional area (CSAmuscle) in the thigh. The subject who continued reduced FES-cycling maintained 96.2% and 95.0% of the previous gain in total and trabecu-lar BMD, and 98.5% in CSAmuscle. Conclusion: Bone and muscle benefits achieved by one year of high-volume FES-cycling are partly preserved after 12 months of detraining whereas reduced cycling maintains bone and muscle mass gained. This suggests that high-volume FES-cycling has clinical relevance for at least 1y after detraining

    Ethical considerations in on-ground applications of the ecosystem services concept

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    The ecosystem services (ES) concept is one of the main avenues for conveying society's dependence on natural ecosystems. On-ground applications of the concept are now widespread and diverse and include its use as a communication tool, for policy guidance and priority setting, and for designing economic instruments for conservation. Each application raises ethical considerations beyond traditional controversies related to the monetary valuation of nature. We review ethical considerations across major on-ground applications and group them into the following categories: anthropocentric framing, economic metaphor, monetary valuation, commodification, sociocultural impact, changes in motivations, and equity implications. Different applications of the ES concept raise different suites of ethical issues, and we propose methods to address the issues most relevant to each application. We conclude that the ES concept should be considered as only one among various alternative approaches to valuing nature and that reliance on economic metaphors can exclude other motivations for protecting ecosystems

    Effect of structural ordering of the carbon support on the behavior of Pd catalysts in aqueous-phase hydrodechlorination

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    Catalysts consisting of Pd supported on virgin and heat-treated carbon blacks (homemade and commercial), graphites (natural and synthetic) and commercial carbon nanofibers were prepared and tested in the aqueous phase hydrodechlorinaton (HDC) of 4-chlorophenol (4-CP) under near ambient conditions (30 °C, 1 atm) in order to explore the effect of the support on the catalytic behavior. The homemade graphitized supports were prepared from commercial carbon black (CB) and from a carbon black-like material (CBPE) obtained from pyrolysis of low-density polyethylene. All the catalysts prepared yielded complete 4-CP conversion, although a wide range of activity was observed (10.7–173.5 mmol gPd−1 min−1). The graphitized carbon black provided the most active catalysts, showing Pd nanoparticles around 3 nm in size and a well-balanced contribution of Pd species (Pdn+/Pd0 = 0.9). Substantial differences of activity were found between the graphitized and not graphitized supports, even for catalysts with similar Pd nanoparticle size. The higher activity of the catalysts with graphitized supports can be partly associated to a more balanced initial Pdn+ to Pd0 ratio. Moreover, higher selectivity to hydrogenation products (cyclohexanone) was also achieved with those catalysts due to a higher contribution of the Pd0 speciesThe authors greatly appreciate financial support from the Spanish MINECO (CTQ2012-32821

    Neuroactive steroids in depression and anxiety disorders: Clinical studies

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    Certain neuroactive steroids modulate ligand-gated ion channels via non-genomic mechanisms. Especially 3 alpha-reduced pregnane steroids are potent positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. During major depression, there is a disequilibrium of 3 alpha-reduced neuroactive steroids, which is corrected by clinically effective pharmacological treatment. To investigate whether these alterations are a general principle of successful antidepressant treatment, we studied the impact of nonpharmacological treatment options on neuroactive steroid concentrations during major depression. Neither partial sleep deprivation, transcranial magnetic stimulation, nor electroconvulsive therapy affected neuroactive steroid levels irrespectively of the response to these treatments. These studies suggest that the changes in neuroactive steroid concentrations observed after antidepressant pharmacotherapy more likely reflect distinct pharmacological properties of antidepressants rather than the clinical response. In patients with panic disorder, changes in neuroactive steroid composition have been observed opposite to those seen in depression. However, during experimentally induced panic induction either with cholecystokinine-tetrapeptide or sodium lactate, there was a pronounced decline in the concentrations of 3 alpha-reduced neuroactive steroids in patients with panic disorder, which might result in a decreased GABAergic tone. In contrast, no changes in neuroactive steroid concentrations could be observed in healthy controls with the exception of 3 alpha,5 alpha-tetrahydrodeoxycorticosterone. The modulation of GABA(A) receptors by neuroactive steroids might contribute to the pathophysiology of depression and anxiety disorders and might offer new targets for the development of novel anxiolytic compounds. Copyright (c) 2006 S. Karger AG, Basel

    Solution of the Bosonic and Algebraic Hamiltonians by using AIM

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    We apply the notion of asymptotic iteration method (AIM) to determine eigenvalues of the bosonic Hamiltonians that include a wide class of quantum optical models. We consider solutions of the Hamiltonians, which are even polynomials of the fourth order with the respect to Boson operators. We also demonstrate applicability of the method for obtaining eigenvalues of the simple Lie algebraic structures. Eigenvalues of the multi-boson Hamiltonians have been obtained by transforming in the form of the single boson Hamiltonian in the framework of AIM

    POEMMA: Probe Of Extreme Multi-Messenger Astrophysics

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    The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being designed to establish charged-particle astronomy with ultra-high energy cosmic rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of UHECRs and CTNs from space will yield orders-of-magnitude increase in statistics of observed UHECRs at the highest energies, and the observation of the cosmogenic flux of neutrinos for a range of UHECR models. These observations should solve the long-standing puzzle of the origin of the highest energy particles ever observed, providing a new window onto the most energetic environments and events in the Universe, while studying particle interactions well beyond accelerator energies. The discovery of CTNs will help solve the puzzle of the origin of UHECRs and begin a new field of Astroparticle Physics with the study of neutrino properties at ultra-high energies.Comment: 8 pages, in the Proceedings of the 35th International Cosmic Ray Conference, ICRC217, Busan, Kore
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