340 research outputs found
On the interaction of wind energy with climate and weather
This study focuses on the interaction of large-scale wind energy with the atmosphere; namely, the impact that a substantial development of the wind resource may have on climate and weather as well as the impact that anthropogenic global warming (AGW) may have on the amount of available energy in the wind.
A large downstream climate response to wind turbines distributed throughout the central United States is shown in model results from the Community Atmosphere Model (CAM). The mean response takes the form of a stationary Rossby wave. Furthermore, a case study is shown where the wind turbines altered a storm system over the North Atlantic. The resulting magnitude of the anomalous 500 hPa geopotential height field is comparable to the range of forecast uncertainty, which indicates that impacts induced in weather systems may be forecastable
Building on this work, a thorough examination of wind farm and atmospheric parameters, including wind farm size, position, and parameterization as well as atmospheric static stability and jet strength is carried out using an idealized version of the Weather Research and Forecasting (WRF) model. Downstream impacts were found to grow in magnitude as wind farm size and the value of damping used to parameterize the wind turbines was increased. Altering the position of the wind farm with respect to the westerlies and synoptic disturbances revealed that the interaction between baroclinic instabilities and the wind farm enables downstream propagation and growth of the wind farm impacts. However, far downstream impacts were observed to be somewhat independent of the wind farm position, i.e., similar downstream effects were noted for model runs initialized with wind farms 20Ā° of longitude from each other. By increasing atmospheric static stability, a fast saturation of wind farm-induced anomalies was observed throughout the atmosphere. This observation is surprising in light of the increased phasing between surface and upper atmospheric anomalies when static stability is low. Anomalies were able to propagate farther downstream over a shorter period of time when jet strength was increased.
To study projected climate change impacts on the wind resource, data from the third phase of the Coupled Model Intercomparison Project (CMIP3) and the North American Regional Climate Change Assessment Project (NARCCAP) were studied. The results are dominated by substantial intermodel variability; however, many of the models project an increase in wind speeds and energy over the central United States. This increase in wind energy is related to an increase in low-frequency, high-speed transient wind speeds, which have a high power density due to the cubic relationship between wind speed and power
Expectations in the field of the Internet and health: an analysis of claims about social networking sites in clinical literature
This article adopts a critical sociological perspective to examine the expectations surrounding the uses of social networking sites (SNSs) articulated in the domain of clinical literature. This emerging body of articles and commentaries responds to the recent significant growth in SNS use, and constitutes a venue in which the meanings of SNSs and their relation to health are negotiated. Our analysis indicates how clinical writing configures the role of SNSs in health care through a range of metaphorical constructions that frame SNSs as a tool, a conduit for information and a traversable space. The use of such metaphors serves not only to describe the new affordances offered by SNSs but also posits distinct lay and professional practices, while reviving a range of celebratory claims about the Internet and health critiqued in sociological literature. These metaphorical descriptions characterise SNS content as essentially controllable by autonomous users while reiterating existing arguments that e-health is both inherently empowering and risky. Our analysis calls for a close attention to these understandings of SNSs as they have the potential to shape future online initiatives, most notably by anticipating successful professional interventions while marginalising the factors that influence usersā online and offline practices and contexts
The Design and Realisation of a 3D-Printed Myoelectric Prosthetic Arm for Toddlers Utilising Soft Grippers
A prosthetic device aims to improve an amputeeās ability to perform activities of daily living, by mimicking the function of a biological arm. The use of a prosthesis has also been shown to minimise some of the issues facing amputees, such as poor posture and muscular skeletal pain. Active, myoelectric-controlled prosthetic arms have primarily focused on adults, despite evidence showing the benefits of early adoption in reducing the rejection rates and aiding in proper motor neural development.
This work presents SIMPA, a low-cost 3D-printed prosthetic arm with a soft-gripper based end device. The arm has been designed using CAD and 3D-scaning and manufactured using predominantly 3Dprinting techniques. This all serves the aim of reducing cost and lead-time, both crucial aspects for prosthetic manufacturing, particularly with the rapid growth rates of young children.
A voluntary opening control system utilising an armband based (surface electromyography) sEMG has been developed concurrently. This simple control system acts as a base for more advanced control structures as the child develops. Grasp tests have resulted in an average effectiveness of 87%, with objects in excess of 400g being securely grasped. Force tests have shown that the arm is performing in line with current adult prosthetic devices. The results highlight the effectiveness of soft grippers as an end device in prosthetics, as well as viability of toddler-scale 3D-printed myoelectric devices
Toward Defining Literacy
Literacy is a topic much on the public\u27s mind these days. It is one of those subjects on which all laypersons think they are experts. When it comes time, however, to establish measures of illiteracy rates or to set policies, it becomes apparent that we know less than we thought we did. It is small comfort to know that specialists also have their differences
Pricing in C2C Sharing Platforms
Sharing platforms such as zilok.com enable sharing of durable goods among consumers, and seek to maximize proļ¬ts by charging transaction-based platform fees. We develop a model in which consumers who have heterogeneous needs concerning the use of a durable good decide whether to purchase and share (i.e., be a lender) or borrow (i.e., be a borrower), and a monopoly sharing platform determines the platform fees. We ļ¬nd, ļ¬rst, that consumers with greater need to use a durable good purchase and share, and that consumers with lesser need borrow. Second, sharing platforms maximize proļ¬ts only if the supply of a durable good matches demandāthat is, the market must clear in order for platform fees to be proļ¬t maximizing. Third, the market-clearing condition requires lender and borrower fees are classic strategic complements. Fourth, to maintain the market-clearing condition, sharing platforms have to increase their lender fee or decrease their borrower fee in response to increases in the sharing price, increases in usage capacity, and decreases in the purchase price of a durable good, and vice versa. These ļ¬ndings indicate that commonly applied one-sided pricing models in sharing platforms can be improved
A Two-Minute Paper-and-Pencil Test of Symbolic and Nonsymbolic Numerical Magnitude Processing Explains Variability in Primary School Children\u27s Arithmetic Competence
Recently, there has been a growing emphasis on basic number processing competencies (such as the ability to judge which of two numbers is larger) and their role in predicting individual differences in school-relevant math achievement. Children\u27s ability to compare both symbolic (e.g. Arabic numerals) and nonsymbolic (e.g. dot arrays) magnitudes has been found to correlate with their math achievement. The available evidence, however, has focused on computerized paradigms, which may not always be suitable for universal, quick application in the classroom. Furthermore, it is currently unclear whether both symbolic and nonsymbolic magnitude comparison are related to children\u27s performance on tests of arithmetic competence and whether either of these factors relate to arithmetic achievement over and above other factors such as working memory and reading ability. In order to address these outstanding issues, we designed a quick (2 minute) paper-and-pencil tool to assess children\u27s ability to compare symbolic and nonsymbolic numerical magnitudes and assessed the degree to which performance on this measure explains individual differences in achievement. Children were required to cross out the larger of two, single-digit numerical magnitudes under time constraints. Results from a group of 160 children from grades 1-3 revealed that both symbolic and nonsymbolic number comparison accuracy were related to individual differences in arithmetic achievement. However, only symbolic number comparison performance accounted for unique variance in arithmetic achievement. The theoretical and practical implications of these findings are discussed which include the use of this measure as a possible tool for identifying students at risk for future difficulties in mathematics. Ā© 2013 Nosworthy et al
A two-minute paper and pencil test of symbolic and nonsymbolic numerical magnitude processing explains variability in primary school childrenās arithmetic competence
Recently, there has been a growing emphasis on basic number processing competencies (such as the ability to judge which of two numbers is larger) and their role in predicting individual differences in school-relevant math achievement. Childrenās ability to compare both symbolic (e.g. Arabic numerals) and nonsymbolic (e.g. dot arrays) magnitudes has been found to correlate with their math achievement. The available evidence, however, has focused on computerized paradigms, which may not always be suitable for universal, quick application in the classroom. Furthermore, it is currently unclear whether both symbolic and nonsymbolic magnitude comparison are related to childrenās performance on tests of arithmetic competence and whether either of these factors relate to arithmetic achievement over and above other factors such as working memory and reading ability. In order to address these outstanding issues, we designed a quick (2 minute) paper-and-pencil tool to assess childrenās ability to compare symbolic and nonsymbolic numerical magnitudes and assessed the degree to which performance on this measure explains individual differences in achievement. Children were required to cross out the larger of two, single-digit numerical magnitudes under time constraints. Results from a group of 160 children from grades 1ā3 revealed that both symbolic and nonsymbolic number comparison accuracy were related to individual differences in arithmetic achievement. However, only symbolic number comparison performance accounted for unique variance in arithmetic achievement. The theoretical and practical implications of these findings are discussed which include the use of this measure as a possible tool for identifying students at risk for future difficulties in mathematics
Lupus nephritis: Correlation of interstitial cells with glomerular function
Lupus nephritis: Correlation of interstitial cells with glomerular function. Mononuclear inflammatory cells were studied using monoclonal antibodies in the interstitium and glomeruli of 35 renal biopsy specimens from patients with lupus nephritis already taking immunosuppressants. The aims of this study were to assess the composition and significance of the infiltrate, and to assess correlations with immediate glomerular function and ability to predict the future course of the disease. The majority of interstitial cells were T lymphocytes and monocytes/macrophages. The number of interstitial CD4 +ve T helper/ inducer lymphocytes was greater than that of CD8 +ve T cytotoxic/ suppressor cells in only 19 out of 35 biopsies, the mean CD4:CD8 ratio being only 1.5 Ā± 1.2. NK cells and B lymphocytes were a minor component only. Some expression of IL-2, transferrin and C3b receptors was seen on interstitial cells, but HLA-DR expressing cells were much in excess of controls and the number of tubular cells expressing HLA-DR was also increased. The number of interstitial T cells, CD4 +ve cells and monocytes/macrophages was highly correlated with the extent of chronic damage judged by optical microscopy. There was also an association between glomerular function at biopsy and numbers of interstitial T cells, CD8 +ve cells, monocytes/macrophages and DR expressing cells. Subsequent decline in renal function, however, was associated only with numbers of monocytes/macrophages and the rather small number of C3b receptor-positive cells. The presence of tubulointerstitial immune aggregates of Ig and/or C in 63% of patients was associated with greater numbers of NK cells. As previously described, the degree of renal function at biopsy correlated with a chronicity index based on optical microscopy. No correlations were found between numbers or types (mostly monocyte/macrophages) of intraglomerular leukocytes and clinical or biopsy features, except that more proliferative types showed greater leukocyte numbers. One hypothesis consistent with our findings is that interstitial T cells and monocytes may be important determinants of pathogenesis and progression of lupus nephritis. While several mechanisms may play an initial role, interstitial monocytes may be the major factor in chronic injury
Synthesis of Silver Nanoparticles by a Bryophilous Rhizoctonia species
We demonstrate the synthesis of silver nanoparticles by a potentially benign species of bryophilous Rhizoctonia in two different media. The first medium supports fungal growth and the upāregulation of nitrate reductase, while the second medium supports fungal growth and the repression of nitrate reductase. For both media, the resulting silver nanoparticles were ca. 25ā50nm and were subglobose to broadly ellipsoidal in shape. The optical analysis of the silver nanoparticles from both media demonstrated plasmon resonance at 415nm, confirming their metallic properties. The liquid colour change typically observed for extracellular silver nanoparticle formation was absent in both media. The silver nanoparticles in the two different media displayed different chemical associations; fewer associated chemicals were found with the media, which supported the upāregulation of nitrate reductase. Another difference included plateālike silver nanoparticle conglomerations, which were only encountered on hyphae from the medium that repressed nitrate reductase. There was also a noticeable difference in the capping agent formations between each media. The Rhizoctonia isolate examined in this study is suitable for largeāscale industrial applications because it does not produce spores and would have minimal impact on air quality
Genome Sequence of the Acidophilic Iron Oxidizer Ferrimicrobium acidiphilum Strain T23T
Extremely acidophilic iron-oxidizing bacteria have largely been characterized for the phyla Proteobacteria and Nitrospira. Here, we report the draft genome of an iron-oxidizing and -reducing heterotrophic mesophile of the Actinobacteria, Ferrimicrobium acidiphilum, which was isolated from an abandoned pyrite mine. The genome sequence comprises 3.08Ā Mb
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