164 research outputs found
Automated control system for the process of managing the procurement of raw materials used in steel making
The article presents a solution to the important problem of developing an automated control system for the process of purchasing raw materials used in metallurgical production. The system is based on an integrated approach that offers the solution that enables the performance of two main tasks: identifying the optimal lot size ordering and selecting a qualified supplier
Si-compatible candidates for high-K dielectrics with the Pbnm perovskite structure
We analyze both experimentally (where possible) and theoretically from
first-principles the dielectric tensor components and crystal structure of five
classes of Pbnm perovskites. All of these materials are believed to be stable
on silicon and are therefore promising candidates for high-K dielectrics. We
also analyze the structure of these materials with various simple models,
decompose the lattice contribution to the dielectric tensor into force constant
matrix eigenmode contributions, explore a peculiar correlation between
structural and dielectric anisotropies in these compounds and give phonon
frequencies and infrared activities of those modes that are infrared-active. We
find that CaZrO_3, SrZrO_3, LaHoO_3, and LaYO_3 are among the most promising
candidates for high-K dielectrics among the compounds we considered.Comment: 17 pages, 9 figures, 4 tables. Supplementary information:
http://link.aps.org/supplemental/10.1103/PhysRevB.82.064101 or
http://www.physics.rutgers.edu/~sinisa/highk/supp.pd
Deletion of growth hormone receptor gene but not visceral fat removal decreases expression of apoptosis-related genes in the kidney—potential mechanism of lifespan extension
Mice homozygous for the targeted disruption of the growth hormone (GH) receptor (Ghr) gene (GH receptor knockout; GHRKO; KO) are hypoinsulinemic, highly insulin sensitive, normoglycemic, and long-lived. Visceral fat removal (VFR) is a surgical intervention which improves insulin signaling in normal (N) mice and rats and extends longevity in rats. We have previously demonstrated decreased expression level of certain pro-apoptotic genes in skeletal muscles and suggested that this may contribute to the regulation of longevity in GHRKO mice. Alterations in apoptosis-related genes expression in the kidneys also may potentially lead to lifespan extension. In this context, we decided to examine the renal expression of the following genes: caspase-3, caspase-9, caspase-8, bax, bad, bcl-2, Smac/DIABLO, Apaf-1, p53, and cytochrome c1 (cyc1) in male GHRKO and N mice subjected to VFR or sham surgery, at approximately 6 months of age. The kidneys were collected 2 months after VFR. As a result, caspase-3, caspase-9, and bax expressions were decreased in KO mice as compared to N animals. Expressions of Smac/DIABLO, caspase-8, bcl-2, bad, and p53 did not differ between KOs and N mice. VFR did not change the expression of the examined genes in KO or N mice. In conclusion, endocrine abnormalities in GHRKO mice result in decreased expression of pro-apoptotic genes and VFR did not alter the examined genes expression in N and KO mice. These data are consistent with a model in which alterations of GH signaling and/or insulin sensitivity lead to increased lifespan mediated by decreased renal expression of pro-apoptotic genes
A Vision for Science Gateways: Bridging the Gap and Broadening the Outreach
The future for science gateways warrants exploration as we consider the possibilities that extend well beyond science and high performance computing into new interfaces, applications and user communities. In this paper, we look retrospectively at the successes of representative gateways thus far. This serves to highlight existing gaps gateways need to overcome in areas such as accessibility, usability and interoperability, and in the need for broader outreach by drawing insights from technology adoption research. We explore two particularly promising opportunities for gateways - computational social sciences and virtual reality – and make the case for the gateway community to be more intentional in engaging with users to encourage adoption and implementation, especially in the area of educational usage. We conclude with a call for focused attention on legal hurdles in order to realize the full future potential of science gateways. This paper serves as a roadmap for a vision of science gateways in the next ten years
Metabolic effects of intra-abdominal fat in GHRKO mice
Mice with targeted deletion of the growth hormone receptor (GHRKO mice) are growth hormone (GH) resistant, small, obese, hypoinsulinemic, highly insulin sensitive and remarkably long-lived. To elucidate the unexpected coexistence of adiposity with improved insulin sensitivity and extended longevity, we examined effects of surgical removal of visceral (epididymal and perinephric) fat on metabolic traits related to insulin signaling and longevity. Comparison of results obtained in GHRKO mice and in normal animals from the same strain revealed disparate effects of visceral fat removal (VFR) on insulin and glucose tolerance, adiponectin levels, accumulation of ectopic fat, phosphorylation of insulin signaling intermediates, body temperature, and respiratory quotient (RQ). Overall, VFR produced the expected improvements in insulin sensitivity and reduced body temperature and RQ in normal mice and had opposite effects in GHRKO mice. Some of the examined parameters were altered by VFR in opposite directions in GHRKO and normal mice, and others were affected in only one genotype or exhibited significant genotype x treatment interactions. Functional differences between visceral fat of GHRKO and normal mice were confirmed by measurements of adipokine secretion, lipolysis, and expression of genes related to fat metabolism. We conclude that in the absence of GH signaling, the secretory activity of visceral fat is profoundly altered and unexpectedly promotes enhanced insulin sensitivity. The apparent beneficial effects of visceral fat in GHRKO mice may also explain why reducing adiposity by calorie restriction fails to improve insulin signaling or further extend longevity in these animals
Exercise Improves Cognitive Responses to Psychological Stress through Enhancement of Epigenetic Mechanisms and Gene Expression in the Dentate Gyrus
Background
We have shown previously that exercise benefits stress resistance and stress coping capabilities. Furthermore, we reported recently that epigenetic changes related to gene transcription are involved in memory formation of stressful events. In view of the enhanced coping capabilities in exercised subjects we investigated epigenetic, gene expression and behavioral changes in 4-weeks voluntarily exercised rats.
Methodology/Principal Findings
Exercised and control rats coped differently when exposed to a novel environment. Whereas the control rats explored the new cage for the complete 30-min period, exercised animals only did so during the first 15 min after which they returned to sleeping or resting behavior. Both groups of animals showed similar behavioral responses in the initial forced swim session. When re-tested 24 h later however the exercised rats showed significantly more immobility behavior and less struggling and swimming. If rats were killed at 2 h after novelty or the initial swim test, i.e. at the peak of histone H3 phospho-acetylation and c-Fos induction, then the exercised rats showed a significantly higher number of dentate granule neurons expressing the histone modifications and immediate-early gene induction.
Conclusions/Significance
Thus, irrespective of the behavioral response in the novel cage or initial forced swim session, the impact of the event at the dentate gyrus level was greater in exercised rats than in control animals. Furthermore, in view of our concept that the neuronal response in the dentate gyrus after forced swimming is involved in memory formation of the stressful event, the observations in exercised rats of enhanced neuronal responses as well as higher immobility responses in the re-test are consistent with the reportedly improved cognitive performance in these animals. Thus, improved stress coping in exercised subjects seems to involve enhanced cognitive capabilities possibly resulting from distinct epigenetic mechanisms in dentate gyrus neurons
Genomic analysis of two phlebotomine sand fly vectors of Leishmania from the New and Old World.
Phlebotomine sand flies are of global significance as important vectors of human disease, transmitting bacterial, viral, and protozoan pathogens, including the kinetoplastid parasites of the genus Leishmania, the causative agents of devastating diseases collectively termed leishmaniasis. More than 40 pathogenic Leishmania species are transmitted to humans by approximately 35 sand fly species in 98 countries with hundreds of millions of people at risk around the world. No approved efficacious vaccine exists for leishmaniasis and available therapeutic drugs are either toxic and/or expensive, or the parasites are becoming resistant to the more recently developed drugs. Therefore, sand fly and/or reservoir control are currently the most effective strategies to break transmission. To better understand the biology of sand flies, including the mechanisms involved in their vectorial capacity, insecticide resistance, and population structures we sequenced the genomes of two geographically widespread and important sand fly vector species: Phlebotomus papatasi, a vector of Leishmania parasites that cause cutaneous leishmaniasis, (distributed in Europe, the Middle East and North Africa) and Lutzomyia longipalpis, a vector of Leishmania parasites that cause visceral leishmaniasis (distributed across Central and South America). We categorized and curated genes involved in processes important to their roles as disease vectors, including chemosensation, blood feeding, circadian rhythm, immunity, and detoxification, as well as mobile genetic elements. We also defined gene orthology and observed micro-synteny among the genomes. Finally, we present the genetic diversity and population structure of these species in their respective geographical areas. These genomes will be a foundation on which to base future efforts to prevent vector-borne transmission of Leishmania parasites
A thermosensitive electromechanical model for detecting biological particles
Miniature electromechanical systems form a class of bioMEMS that can provide appropriate sensitivity. In this research, a thermo-electro-mechanical model is presented to detect biological particles in the microscale. Identification in the model is based on analyzing pull-in instability parameters and frequency shifts. Here, governing equations are derived via the extended Hamilton’s principle. The coupled effects of system parameters such as surface layer energy, electric field correction, and material properties are incorporated in this thermosensitive model. Afterward, the accuracy of the present model and obtained results are validated with experimental, analytical, and numerical data for several cases. Performing a parametric study reveals that mechanical properties of biosensors can significantly affect the detection sensitivity of actuated ultra-small detectors and should be taken into account. Furthermore, it is shown that the number or dimension of deposited particles on the sensing zone can be estimated by investigating the changes in the threshold voltage, electrode deflection, and frequency shifts. The present analysis is likely to provide pertinent guidelines to design thermal switches and miniature detectors with the desired performance. The developed biosensor is more appropriate to detect and characterize viruses in samples with different temperatures
The scandium effect in multicomponent alloys
Despite its excellent elemental properties, lightweight nature and good alloying potential, scandium has received relatively little attention in the manufacturing community. The abundance of scandium in the Earth's crust is quite high. It is more abundant than silver, cobalt, lead and tin. But, because scandium is so well dispersed in the lithosphere, it is notoriously difficult to extract in commercial quantities – hence low market availability and high cost. Scandium metallurgy is still a largely unexplored field – but progress is being made. This review aims to summarise advances in scandium metallurgical research over the last decade. The use of scandium as a conventional minor addition to alloys, largely in structural applications, is described. Also, more futuristic functional applications are discussed where details of crystal structures and peculiar symmetries are often of major importance. This review also includes data obtained from more obscure sources (especially Russian publications) which are much less accessible to the wider community. It is clear that more fundamental research is required to elevate the status of scandium from a laboratory-based curiosity to a mainstream alloying element. This is largely uncharted territory. There is much to be discovered
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