Driving current through single organic molecules

We investigate electronic transport through two types of conjugated molecules. Mechanically controlled break-junctions are used to couple thiol endgroups of single molecules to two gold electrodes. Current-voltage characteristics (IVs) of the metal-molecule-metal system are observed. These IVs reproduce the spatial symmetry of the molecules with respect to the direction of current flow. We hereby unambigously detect an intrinsic property of the molecule, and are able to distinguish the influence of both the molecule and the contact to the metal electrodes on the transport properties of the compound system.Comment: 4 pages, 5 figure

Micro-spectroscopy on silicon wafers and solar cells

Micro-Raman (μRS) and micro-photoluminescence spectroscopy (μPLS) are demonstrated as valuable characterization techniques for fundamental research on silicon as well as for technological issues in the photovoltaic production. We measure the quantitative carrier recombination lifetime and the doping density with submicron resolution by μPLS and μRS. μPLS utilizes the carrier diffusion from a point excitation source and μRS the hole density-dependent Fano resonances of the first order Raman peak. This is demonstrated on micro defects in multicrystalline silicon. In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates. This can be attributed to the strong stress dependence of the carrier mobility (piezoresistance) of silicon. With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes

A retrospective study on the impact of comorbid depression or anxiety on healthcare resource use and costs among diabetic neuropathy patients

<p>Abstract</p> <p>Background</p> <p>Diabetic neuropathy (DN) is a common complication of diabetes that has significant economic burden, especially for patients with comorbid depression or anxiety. This study examines and quantifies factors associated with healthcare costs among patients diagnosed with diabetic neuropathy (DN) with or without a comorbid diagnosis of depression or anxiety (DA) using retrospective administrative claims data. No study has examined the differences in economic outcomes depending on the presence of comorbid DA disorders.</p> <p>Methods</p> <p>Over-age-18 individuals with 1+ diagnosis of DN in 2005 were selected. The first observed DN claim was considered the "index date." All individuals had a 12-month pre-index and follow-up period. For both under-age-65 commercially insured and over-age-65 individuals with employer-sponsored Medicare supplemental insurance, we constructed 2 subgroups for individuals with DA (DN-DA) or without (DN-only). Patients' clinical characteristics over pre-index period were compared. Multivariate regressions were performed to assess whether DN-DA patients had higher utilization of healthcare resources and costs than DN-only patients, controlling for demographic and clinical characteristics.</p> <p>Results</p> <p>We identified 16,831 DN-only and 1,699 DN-DA patients in the Medicare supplemental cohort, as well as 17,205 and 3,105 in the commercially insured. DN-DA patients had higher prevalence of diabetes-related comorbidities for cardiovascular disease, cerebrovascular/peripheral vascular disease, nephropathy, obesity, and hypoglycemic events than DN-only patients (all p < 0.05). Controlling for differences in demographic and clinical characteristics, DN-DA patients had $9,235 (p < 0.05) higher total healthcare costs than patients with DN-only among those with Medicare supplemental coverage ($26,718 vs. $17,483), and$10,389 (p < 0.05) more total costs among commercially insured ($29,775 vs.$19,386). Factors associated with increased costs included insurance type, geographical region, diabetes-related comorbidities, and insulin therapy.</p> <p>Conclusion</p> <p>These findings indicate that the healthcare costs were significantly higher for DN patients with depression or anxiety relative to those without such comorbid disorders.</p

Anuros de Itaiópolis : subsídios para a elaboração de uma cartilha educativa

Orientador : Vinícius AbilhoaMonografia (especialização) - Universidade Federal do Paraná, Setor de Ciências da Terra, Curso de Especialização em Análise AmbientalInclui referência

Electric Field-Driven Water Dipoles: Nanoscale Architecture of Electroporation

<div><p>Electroporation is the formation of permeabilizing structures in the cell membrane under the influence of an externally imposed electric field. The resulting increased permeability of the membrane enables a wide range of biological applications, including the delivery of normally excluded substances into cells. While electroporation is used extensively in biology, biotechnology, and medicine, its molecular mechanism is not well understood. This lack of knowledge limits the ability to control and fine-tune the process. In this article we propose a novel molecular mechanism for the electroporation of a lipid bilayer based on energetics analysis. Using molecular dynamics simulations we demonstrate that pore formation is driven by the reorganization of the interfacial water molecules. Our energetics analysis and comparisons of simulations with and without the lipid bilayer show that the process of poration is driven by field-induced reorganization of water dipoles at the water-lipid or water-vacuum interfaces into more energetically favorable configurations, with their molecular dipoles oriented in the external field. Although the contributing role of water in electroporation has been noted previously, here we propose that interfacial water molecules are the main players in the process, its initiators and drivers. The role of the lipid layer, to a first-order approximation, is then reduced to a relatively passive barrier. This new view of electroporation simplifies the study of the problem, and opens up new opportunities in both theoretical modeling of the process and experimental research to better control or to use it in new, innovative ways.</p></div

Amphibia, Anura, Hylidae, Dendropsophus microps (Peters, 1872): distribution extension in state of São Paulo, Brazil and first record in Cerrado domain

Non

Aparasphenodon brunoi Miranda-Ribeiro, 1920 (Anura: Hylidae): distribution extension and geographic distribution map for Bahia state, Brazil

The casque-headed frog Aparasphenodon brunoi is recorded for the first time in the municipalities of Ilhéus and Igrapiúna, southern region of Bahia state, northeastern Brazil. The new record of A. brunoi in the municipality of Igrapiúna, represents an increase of its known geographic distribution of approximately 150 km north from its nearest locality (airline), in municipality of Una, state of Bahia, representing now the northernmost known record for this species

Prospects of Cattle Farming in an Era of Land Degradation-Perceptions of the Farmers in the Okakarara Communal Area, Namibia

Livestock farming plays an important role in many rural people s’ livelihoods around the globe. The sector is, however, faced with numerous challenges, particularly land degradation. Namibia, one of the driest countries in the world, is no exception to land degradation challenges, mostly among communal rangeland areas. Several studies and interventions on land degradation have been conducted in the country, however, with limited or no information on farmers\u27 perceptions. Although land degradation may be a physical process, understanding its causes, process, indicators, and effects from the own users’ is indispensable. Here, we assessed farmers\u27 perception in the eastern part of Namibia, Okakarara communal area. We conducted detailed interviews with 41 livestock farming households, selected through purposive sampling, from four villages. We documented how farmers perceive cattle farming in their areas amid land degradation and the interventions that they intend to make to sustain their livelihood in the future. Amongst others, farmers perceive livestock farming to be costly, relying mainly on procured supplements (97%), rangelands will deteriorate further due to increasing droughts (85%) and the land will become more bush encroached. To overcome future farming uncertainties, over 70% of the farmers state that they aim to diversify farming practices e.g. engaging in crop farming, use encroacher bushes to feed livestock (51%), planting grasses and preserving grasses for drought conditions (37%) as other key interventions to sustain livelihoods. Interestingly, removing the encroached bushes (de-bushing) was only mentioned by few farmers (10 %) as an intervention to improve rangelands. This is despite that the technique has lately gained momentum in the country as one of the solutions to overcome rangeland degradation. This could imply, farmers, are not yet made aware of the de-bushing techniques. The study suggests future community programs such as on-farm range research and development should consider farmers\u27 views instead of side lining them

Conceptual comparison between standard Si solar cells and back contacted cells

It is often stated that one of the main advantages of back-contacted (BC) Si solar cells over standard cells is that shading due to the front-finger metallization is avoided - while it is also often stated that BC cells are prone to "electronic shadowing", which means that the carrier collection efficiency in front of the back-surface-field (BSF) may be reduced. We compare these two cell concepts in two ways: by means of an extensive collection of measured IV data from literature, and by interpreting as well as quantifying the differences with the aid of numerical device simulation. Both literature data and simulations indicate that BC cells have a Jsc-advantage of maximally about 1 mA/cm2, but in Voc and FF there is no clear advantage or disadvantage over standard cells. With a parameter study, we reveal the main design advantages and weaknesses in each cell type. Our numerical device modeling indicates that one of the most crucial design advantages of BC over standard cells is that the collection of minority carriers in the emitter is rather unimportant, which leaves greater flexibility in emitter design than in standard cells