918 resultados para arc- and plasma jet facilities


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The development of the distributed information measurement and control system for optical spectral research of particle beam and plasma objects and the execution of laboratory works on Physics and Engineering Department of Petrozavodsk State University are described. At the hardware level the system is represented by a complex of the automated workplaces joined into computer network. The key element of the system is the communication server, which supports the multi-user mode and distributes resources among clients, monitors the system and provides secure access. Other system components are formed by equipment servers (CАМАC and GPIB servers, a server for the access to microcontrollers MCS-196 and others) and the client programs that carry out data acquisition, accumulation and processing and management of the course of the experiment as well. In this work the designed by the authors network interface is discussed. The interface provides the connection of measuring and executive devices to the distributed information measurement and control system via Ethernet. This interface allows controlling of experimental parameters by use of digital devices, monitoring of experiment parameters by polling of analog and digital sensors. The device firmware is written in assembler language and includes libraries for Ethernet-, IP-, TCP- и UDP-packets forming.

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The current platform of conventional cardiovascular risk assessments tends to forsake the importance of endothelial function - a key biological mechanism by which cardiovascular risk factors exert their propensity for adverse vascular events. Moreover, the presence and severity of endothelial dysfunction in ‘low-risk’ individuals suggests considerable variability in pre-clinical risk that could potentially be detected well before the onset of disease. The aim of the present thesis was to investigate the presence and impact of retinal vascular dysfunction, as a barometer of endothelial function, in otherwise healthy individuals with one or more cardiovascular risk factors, but low to moderate cardiovascular risk. Systemic circulatory influences on retinal vascular function were also evaluated. The principle sections and findings of this work are: 1. Ageing effect on retinal vascular function • In low-risk individuals, there are age differences in retinal vascular function throughout the entire functional response curve for arteries and veins. Gender differences mainly affect the dilatory phase and are only present in young individuals. 2. Retinal vascular function in healthy individuals with a family history of cardiovascular disease • In low-risk individuals with a family history of cardiovascular disease, impairments in microvascular function at the retinal level correlate with established plasma markers for cardiovascular risk. 3. Ethnic differences in retinal vascular function • When compared to age-matched White Europeans, in low-risk middle-aged South Asians, there are impairments in retinal vascular function that correlate with established cardiovascular risk indicators. 4. Systemic circulatory influences on retinalµvascular function • Systemic antioxidant capacity (redox index) and plasma markers for cardiovascular risk (lipids) influence retinal microvascular function at both arterial and venous levels. 5. Retinal vascular function in individuals with obstructive sleep apnoea: a preliminarystudy • Patients with moderate to severe sleep apnoea exhibit attenuated retinal vascular function.

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The approach of all ophthalmologists, diabetologists and general practitioners seeing patients with diabetic retinopathy should be that good control of blood glucose, blood pressure and plasma lipids are all essential components of modern medical management. The more recent data on the use of fenofibrate in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) and The Action to Control Cardiovascular Risk in Diabetes (ACCORD) Eye studies is reviewed. In FIELD, fenofibrate (200 mg/day) reduced the requirements for laser therapy and prevented disease progression in patients with pre-existing diabetic retinopathy. In ACCORD Eye, fenofibrate (160 mg daily) with simvastatin resulted in a 40% reduction in the odds of retinopathy progressing over 4 years, compared with simvastatin alone. This occurred with an increase in HDL-cholesterol and a decrease in the serum triglyceride level in the fenofibrate group, as compared with the placebo group, and was independent of glycaemic control. We believe fenofibrate is effective in preventing progression of established diabetic retinopathy in type 2 diabetes and should be considered for patients with pre-proliferative diabetic retinopathy and/or diabetic maculopathy, particularly in those with macular oedema requiring laser. © 2011 Macmillan Publishers Limited All rights reserved.

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Aims: Obesity and Type 2 diabetes are associated with accelerated ageing. The underlying mechanisms behind this, however, are poorly understood. In this study, we investigated the association between circulating irisin - a novel my okine involved in energy regulation - and telomere length (TL) (a marker of aging) in healthy individuals and individuals with Type 2 diabetes. Methods: Eighty-two healthy people and 67 subjects with Type 2 diabetes were recruited to this cross-sectional study. Anthropometric measurements including body composition measured by biompedance were recorded. Plasma irisin was measured by ELISA on a fasted blood sample. Relative TL was determined using real-time PCR. Associations between anthropometric measures and irisin and TL were explored using Pearson’s bivariate correlations. Multiple regression was used to explore all the significant predictors of TL using backward elimination. Results: In healthy individuals chronological age was a strong negative predictor of TL (=0.552, p < 0.001). Multiple regression analysis using backward elimination (excluding age) revealed the greater relative TL could be predicted by greater total muscle mass(b = 0.046, p = 0.001), less visceral fat (b = =0.183, p < 0.001)and higher plasma irisin levels (b = 0.01, p = 0.027). There were no significant associations between chronological age, plasmairisin, anthropometric measures and TL in patients with Type 2diabetes (p > 0.1). Conclusion: These data support the view that body composition and plasma irisin may have a role in modulation of energy balance and the aging process in healthy individuals. This relationship is altered in individuals with Type 2 diabetes.

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This study used paleobathymetric interpretations from benthic foraminiferal assemblages to determine the timing of the initial subduction of the Cocos Ridge beneath the Costa Rica-Panama Arc and the associated amount of uplift. Forty-seven samples from four stratigraphic sections of the Burica and the Armuelles formations yielded 217 identified species. Foraminiferal paleoecology and cluster analyses indicated paleobathymetric differences within and between the sections. Maximum and minimum uplift rates were calculated from the biochronology, elevation, paleobathymetry and estimated eustatic changes. Large decreases in paleobathymetry were mainly due to the initial middle Pleistocene subduction of the Cocos Ridge in less than 0.5 Ma. Uplift rates were uneven across the Burica Peninsula, as follows: La Vaca 4.5–0.8 m/ky, Rabo de Puerco 2.8–0.7 m/ky, San Bartolo–Chiquito 2.7–0.8 m/ky, and eastern coast 8.0–1.5 m/ky. These differences probably resulted from Cocos Ridge asymmetry and differential uplift of tectonic blocks.

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Hydroxyapatite (HA) has received wide attention in orthopedics, due to its biocompatibility and osseointegration ability. Despite these advantages, the brittle nature and low fracture toughness of HA often results in rapid wear and premature fracture of implant. Hence, there is a need to improve the fracture toughness and wear resistance of HA without compromising its biocompatibility. ^ The aim of the current research is to explore the potential of nanotubes as reinforcement to HA for orthopedic implants. HA- 4 wt.% carbon nanotube (CNT) composites and coatings are synthesized by spark plasma sintering and plasma spraying respectively, and investigated for their mechanical, tribological and biological behavior. CNT reinforcement improves the fracture toughness (>90%) and wear resistance (>66%) of HA for coating and free standing composites. CNTs have demonstrated a positive influence on the proliferation, differentiation and matrix mineralization activities of osteoblasts, during in-vitro biocompatibility studies. In-vivo exposure of HA-CNT coated titanium implant in animal model (rat) shows excellent histocompatibility and neobone integration on the implant surface. The improved osseointegration due to presence of CNTs in HA is quantified by the adhesion strength measurement of single osteoblast using nano-scratch technique. ^ Considering the ongoing debate about cytotoxicity of CNTs in the literature, the present study also suggests boron nitride nanotube (BNNT) as an alternative reinforcement. BNNT with the similar elastic modulus and strength as CNT, were added to HA. The resulting composite having 4 wt.% BNNTs improved the fracture toughness (∼85%) and wear resistance (∼75%) of HA in the similar range as HA-CNT composites. BNNTs were found to be non-cytotoxic for osteoblasts and macrophages. In-vitro evaluation shows positive role of BNNT in osteoblast proliferation and viability. Apatite formability of BNNT surface in ∼4 days establishes its osseointegration ability.^

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For the first time, the Z0 boson angular distribution in the center-of-momentum frame is measured in proton-proton collisions at [special characters omitted] = 7 TeV at the CERN LHC. The data sample, recorded with the CMS detector, corresponds to an integrated luminosity of approximately 36 pb–1 . Events in which there is a Z0 and at least one jet, with a jet transverse momentum threshold of 20 GeV and absolute jet rapidity less than 2.4, are selected for the analysis. Only the Z0's muon decay channel is studied. Within experimental and theoretical uncertainties, the measured angular distribution is in agreement with next-to-leading order perturbative QCD predictions.

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Cotton is the most abundant natural fiber in the world. Many countries are involved in the growing, importation, exportation and production of this commodity. Paper documentation claiming geographic origin is the current method employed at U.S. ports for identifying cotton sources and enforcing tariffs. Because customs documentation can be easily falsified, it is necessary to develop a robust method for authenticating or refuting the source of the cotton commodities. This work presents, for the first time, a comprehensive approach to the chemical characterization of unprocessed cotton in order to provide an independent tool to establish geographic origin. Elemental and stable isotope ratio analysis of unprocessed cotton provides a means to increase the ability to distinguish cotton in addition to any physical and morphological examinations that could be, and are currently performed. Elemental analysis has been conducted using LA-ICP-MS, LA-ICP-OES and LIBS in order to offer a direct comparison of the analytical performance of each technique and determine the utility of each technique for this purpose. Multivariate predictive modeling approaches are used to determine the potential of elemental and stable isotopic information to aide in the geographic provenancing of unprocessed cotton of both domestic and foreign origin. These approaches assess the stability of the profiles to temporal and spatial variation to determine the feasibility of this application. This dissertation also evaluates plasma conditions and ablation processes so as to improve the quality of analytical measurements made using atomic emission spectroscopy techniques. These interactions, in LIBS particularly, are assessed to determine any potential simplification of the instrumental design and method development phases. This is accomplished through the analysis of several matrices representing different physical substrates to determine the potential of adopting universal LIBS parameters for 532 nm and 1064 nm LIBS for some important operating parameters. A novel approach to evaluate both ablation processes and plasma conditions using a single measurement was developed and utilized to determine the "useful ablation efficiency" for different materials. The work presented here demonstrates the potential for an a priori prediction of some probable laser parameters important in analytical LIBS measurement.

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Low-rise buildings are often subjected to high wind loads during hurricanes that lead to severe damage and cause water intrusion. It is therefore important to estimate accurate wind pressures for design purposes to reduce losses. Wind loads on low-rise buildings can differ significantly depending upon the laboratory in which they were measured. The differences are due in large part to inadequate simulations of the low-frequency content of atmospheric velocity fluctuations in the laboratory and to the small scale of the models used for the measurements. A new partial turbulence simulation methodology was developed for simulating the effect of low-frequency flow fluctuations on low-rise buildings more effectively from the point of view of testing accuracy and repeatability than is currently the case. The methodology was validated by comparing aerodynamic pressure data for building models obtained in the open-jet 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. Field measurements of pressures on Texas Tech University building and Silsoe building were also used for validation purposes. The tests in partial simulation are freed of integral length scale constraints, meaning that model length scales in such testing are only limited by blockage considerations. Thus the partial simulation methodology can be used to produce aerodynamic data for low-rise buildings by using large-scale models in wind tunnels and WOW-like facilities. This is a major advantage, because large-scale models allow for accurate modeling of architectural details, testing at higher Reynolds number, using greater spatial resolution of the pressure taps in high pressure zones, and assessing the performance of aerodynamic devices to reduce wind effects. The technique eliminates a major cause of discrepancies among measurements conducted in different laboratories and can help to standardize flow simulations for testing residential homes as well as significantly improving testing accuracy and repeatability. Partial turbulence simulation was used in the WOW to determine the performance of discontinuous perforated parapets in mitigating roof pressures. The comparisons of pressures with and without parapets showed significant reductions in pressure coefficients in the zones with high suctions. This demonstrated the potential of such aerodynamic add-on devices to reduce uplift forces.

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Understanding how natural and anthropogenic drivers affect extant food webs is critical to predicting the impacts of climate change and habitat alterations on ecosystem dynamics. In the Florida Everglades, seasonal reductions in freshwater flow and precipitation lead to annual migrations of aquatic taxa from marsh habitats to deep-water refugia in estuaries. The timing and intensity of freshwater reductions, however, will be modified by ongoing ecosystem restoration and predicted climate change. Understanding the importance of seasonally pulsed resources to predators is critical to predicting the impacts of management and climate change on their populations. As with many large predators, however, it is difficult to determine to what extent predators like bull sharks (Carcharhinus leucas) in the coastal Everglades make use of prey pulses currently. We used passive acoustic telemetry to determine whether shark movements responded to the pulse of marsh prey. To investigate the possibility that sharks fed on marsh prey, we modelled the predicted dynamics of stable isotope values in bull shark blood and plasma under different assumptions of temporal variability in shark diets and physiological dynamics of tissue turnover and isotopic discrimination. Bull sharks increased their use of upstream channels during the late dry season, and although our previous work shows long-term specialization in the diets of sharks, stable isotope values suggested that some individuals adjusted their diets to take advantage of prey entering the system from the marsh, and as such this may be an important resource for the nursery. Restoration efforts are predicted to increase hydroperiods and marsh water levels, likely shifting the timing, duration and intensity of prey pulses, which could have negative consequences for the bull shark population and/or induce shifts in behaviour. Understanding the factors influencing the propensity to specialize or adopt more flexible trophic interactions will be an important step in fully understanding the ecological role of predators and how ecological roles may vary with environmental and anthropogenic changes.

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Stable isotope analysis has become a standard ecological tool for elucidating feeding relationships of organisms and determining food web structure and connectivity. There remain important questions concerning rates at which stable isotope values are incorporated into tissues (turnover rates) and the change in isotope value between a tissue and a food source (discrimination values). These gaps in our understanding necessitate experimental studies to adequately interpret field data. Tissue turnover rates and discrimination values vary among species and have been investigated in a broad array of taxa. However, little attention has been paid to ectothermic top predators in this regard. We quantified the turnover rates and discrimination values for three tissues (scutes, red blood cells, and plasma) in American alligators (Alligator mississippiensis). Plasma turned over faster than scutes or red blood cells, but turnover rates of all three tissues were very slow in comparison to those in endothermic species. Alligator δ15N discrimination values were surprisingly low in comparison to those of other top predators and varied between experimental and control alligators. The variability of δ15N discrimination values highlights the difficulties in using δ15N to assign absolute and possibly even relative trophic levels in field studies. Our results suggest that interpreting stable isotope data based on parameter estimates from other species can be problematic and that large ectothermic tetrapod tissues may be characterized by unique stable isotope dynamics relative to species occupying lower trophic levels and endothermic tetrapods.

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Introduction: The United States today has become "meeting-conscious." The complexity of conducting business has led to the need for sophisticated coordination of decision-making processes on all levels of the organization. Company meetings have played an increasingly important role in the success and future of many companies. Strategies and decisions are developed at meetings that can determine future policies of crucial importance. Executive training can mean the difference in whether the company will even survive. Large and growing companies have increased their off-premise meeting budgets annually in spite of the state of the economy. however, the rising costs of travel and lodging have made management monitor these budgets more closely than ever. Thus, the need to use every dollar efficiently has compelled companies to examine newer methods of running meetings and alternatives to the usage of typical off-premise meeting facilities. The importance of off-premise meetings in the United States economy has greatly increased due to the billions of dollars spent annually. These factors make it vital to explore the effectiveness of time and monetary expenditures. Up until the mid-1960's, company meetings were held in facilities of various design and purpose, none of which were specifically designed for the small to medium corporate meeting. Upon gathering information concerning the meetings market and the corporate meeting planner, certain individuals endeavored to change the situation. This study is designed to investigate this new concept, which will hereafter be referred to as "conference center." For the purpose of this study, the following two definitions will be used. 1. Conference center - that meeting facility primarily marketing its facilities for the small to medium-sized corporate meeting. The center is operated by specialists aware of market needs in as much detail as are those people working for the company involved. On-premise sleeping rooms are not mandatory provided such facilities are within easy access. 2. Meeting planner - that person within an organization who has primary responsibility for arranging off-premise meetings and all other related items necessary for meeting effectiveness. This person may spend anywhere from 10 to 100l of his time in this capacity. The conference center has effectively satisfied the need for specialized corporate meeting facilities. This study will show the depth of the corporate meetings market and trace the growth and development of this relatively new conference center concept. Information will also be compiled on the top centers in the country. It is hoped that by presenting this research meeting planners will become more aware of the nature and location of these centers, especially for use by the small to medium-sized company. Such exposure of the centers will hopefully increase existing demand and enable the construction of new, innovative centers.

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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

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L’attività di tesi ha previsto la progettazione e realizzazione di sorgenti di plasma di non equilibrio a pressione atmosferica e l’individuazione delle condizioni operative ottimali per l’idrofobizzazione di materiali tessili. La prima parte delle attività di tesi hanno riguardato lo studio e l’approfondimento della letteratura scientifica al fine di individuare le sorgenti e i processi plasma assistiti per l’idrofobizzazione dei materiali. Relativamente alle sorgenti di plasma di non-equilibrio a pressione atmosferica, studi di letteratura riportano che sorgenti di tipo APPJ (Atmospheric Pressure Plasma Jet) consentono di effettuare un trattamento localizzato in un punto, mentre sorgenti DBD (Dielectric Barrier Discharge) risultano idonee a trattamenti di materiali large area. Per quanto riguarda i processi plasma assistiti, sulla base di quanto riportato in letteratura il processo di idrofobizzazione può avvenire principalmente mediante polimerizzazione di gas organici contenenti fluoro, introdotti nella regione di plasma, con la conseguente deposizione di coating fluorurati. Le attività sperimentali condotte durante la tesi hanno avuto l’obbiettivo di valutare la possibilità di rendere idrofobico un filato di fibra tessile naturale mediante l’utilizzo di una sorgente plasma jet operante con miscela di argon e gas organoflorurato. Il filato, messo in moto a diverse velocità, è stato fatto transitare attraverso la piuma di plasma. In particolare, si è passati da una velocità di movimentazione di 1 m/min a una di 10 m/min. I risultati ottenuti hanno evidenziato che maggiore è la velocità di movimentazione del filato attraverso la piuma di plasma, minore è il grado di idrofibizzazione raggiungibile sul filato stesso, in quanto minore è il tempo di esposizione del materiale al plasma. Infine, nell’ultima parte dell’attività di tesi, è stata progettata una sorgente DBD, che caratterizzata da una maggiore area di generazione del plasma rispetto alla sorgente plasma jet, consente di incrementare il tempo di esposizione del filato al plasma a parità di velocità di movimentazione del filato.

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The aim of this present study was to investigate if overweight individuals exhibit signs of vascular dysfunction associated with a high risk for cardiovascular disease (CVD). One hundred lean and 100 overweight participants were recruited for the present study. Retinal microvascular function was assessed using the Dynamic Retinal Vessel Analyser (DVA), and systemic macrovascular function by means of flow-mediated dilation (FMD). Investigations also included body composition, carotid intimal-media thickness (c-IMT), ambulatory blood pressure monitoring (BP), fasting plasma glucose, triglycerides (TG), cholesterol levels (HDL-C and LDL-C), and plasma von Willebrand factor (vWF). Overweight individuals presented with higher right and left c-IMT (p = 0.005 and p = 0.002, respectively), average 24-h BP values (all p <0.001), plasma glucose (p = 0.008), TG (p = 0.003), TG: HDL-C ratio (p = 0.010), and vWF levels (p = 0.004). Moreover, overweight individuals showed lower retinal arterial microvascular dilation (p = 0.039) and baseline-corrected flicker (bFR) responses (p = 0.022), as well as, prolonged dilation reaction time (RT, p = 0.047). These observations emphasise the importance of vascular screening and consideration of preventive interventions to decrease vascular risk in all individuals with adiposity above normal range.