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Search Results: 1 - 10 of 19997 matches for " Richard Levi "
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Mindfulness and Aerobic Exercise as an Intervention for Cognitive Dysfunction Following an Acquired Brain Injury: A Pilot Study  [PDF]
Lovisa Hellgren, Anna Lundqvist, Bj?rn B?rsbo, Richard Levi, Kersti Samuelsson
Open Journal of Therapy and Rehabilitation (OJTR) , 2019, DOI: 10.4236/ojtr.2019.71002
Abstract: Background: Cognitive impairments as sequelae of brain injury are common and can negatively affect activities of everyday life, participation and quality of life. Thus, finding ways to reduce cognitive impairments and ameliorate their negative impact on everyday life is an important focus of research. Aim: The aim of this pilot study was to analyse the effects of a combination of guided mindfulness and aerobic exercise on cognitive ability and mental fatigue in patients with acquired brain injury (ABI). Design: Pilot study, with a before-after design. Setting: Outpatient. Population: Twenty-one patients suffering from ABI, former patients of three rehabilitation medicine departments. Methods: The intervention comprised a structured combination of guided mindfulness program and outdoor walking, three times/week for 12 weeks. The outcome measures included assessment of information processing speed, working memory, oxygen uptake and self-reported mental fatigue. Results: The main results showed improvements in cognitive abilities related to information processing speed, perceived mental fatigue and physical capacity. Conclusions: A combination of mindfulness and physical activity can increase information processing speed and ameliorate mental fatigue. Further studies are needed to confirm our findings. Clinical Rehabilitation Impact: The combination of guided mindfulness and physical activity shows promise as a treatment modality in rehabilitation of impaired information processing speed and mental fatigue following ABI.
Flow Measurements Using Particle Image Velocimetry in the Ultracompact Combustor
Levi M. Thomas,Richard D. Branam,Mark F. Reeder
International Journal of Aerospace Engineering , 2012, DOI: 10.1155/2012/756463
Abstract: The potential for the ultracompact combustor (UCC) lie in future research to reduced fuel consumption and improved engine performance. Velocity measurements performed on the UCC test rig at the Air Force Institute of Technology revealed flow patterns and time-averaged turbulence statistics for data taken burning hydrogen fuel in a straight and a curved cavity vane configuration. Over an equivalence ratio from 0.7 to 1.5, the straight vane configuration showed spanwise velocity decreased linearly with distance from the cavity vane over the width of the main channel. Increasing the flow rates and holding the equivalence ratio and ratio of cavity to main airflow rates constant, flow velocities in the main channel showed an increase with the curved circumferential configuration but a decrease with the straight circumferential configuration. Turbulence intensity is expected to be a major contributing factor, specifically since measured at 15% and 21% in the main channel for the straight and curved configurations, respectively. The results also show how the radial vane cavity (RVC) created strong vorticity throughout the main flow supporting a recirculation zone for mixing. Peak vorticity occurred farthest from the cavity vane suggesting the angle of the radial vane cavity is effective in generating increasing flow rotation. 1. Introduction The concept of an ultracompact combustor (UCC) has been in development for over ten years, offering the potential advantages of increasing gas turbine engine (GTE) performance while decreasing overall length and weight as described in [1–3]. Enabled by its short axial length, a UCC could be used in a GTE in place of the conventional main burner, as an interturbine burner, or both. Instead of using the axial length between the compressor and turbine, the UCC uses a channel around the engine’s circumference for the primary combustion zone (Figure 1). The combustion reaction is cavity-stabilized using trapped vortex combustion (TVC) along the outer wall of the circumferential flow path. By utilizing the circumference of the engine to complete the primary combustion, studies have shown the combustor section of a GTE could be shortened by 66% while maintaining 99% combustion efficiency [4]. Figure 1: Cross-section of (a) UCC pictorial concept and (b) trapped vortex combustion [ 5]. Specific thrust, a measure of thrust per unit air mass flow, of modern GTEs, is primarily limited by the maximum allowable turbine inlet temperature [6]. As GTE main combustors operate lean overall, burning additional fuel will raise the turbine
Knowledge and perception about stroke among an Australian urban population
Sung Sug Yoon, Richard F Heller, Christopher Levi, John Wiggers
BMC Public Health , 2001, DOI: 10.1186/1471-2458-1-14
Abstract: A random sample of households was selected from an electronic telephone directory in Newcastle and Lake Macquarie area of New South Wales, Australia, between 10 September and 13 October 1999. Within each household the person who was between 18 and 80 years of age and who had the next birthday was eligible to participate in the study (1325 households were eligible). The response rate was 62%.The most common symptoms of stroke listed by respondents were "Sudden difficulty of speaking, understanding or reading" identified by 60.1% of the respondents, and "paralysis on one side of body" identified by 42.0% of the respondents. The level of knowledge of the prevalence of a stroke, full recovery after the stroke, and death from stroke was low and generally overestimated. 69.9% of the respondents considered strokes as being either moderately or totally preventable. There were few predictors of knowledge.The study suggests that educational strategies may be required to improve knowledge about a wide range of issues concerning stroke in the community, as a prelude to developing preventive programmes.Stroke remains a leading cause of death, long-term disability, and health care expenditure, but opportunities exist for reducing its cost to the community [1]. Recent advances in the treatment of acute ischemic stroke offer hope in reducing its devastating effects [2,3]. Primary prevention is also an important approach to substantially reducing the prevalence, recurrence, disability, and mortality of stroke [4-7].Previous studies have shown that the knowledge of stroke among patients and in the community is poor. Pancioli and colleagues, [8] in a population based survey, found that 57% of respondents identified at least one of five established warning signs of stroke, 28 % correctly listed two or more, and only 8% correctly identified three established warning signs of stroke. Our previous study [9] showed that only 73.4% of respondents from a random population sample identified t
Shallow Water Quasi-Geostrophic Theory on the Sphere
Wayne H. Schubert,Richard K. Taft,Levi G. Silvers
Journal of Advances in Modeling Earth Systems , 2009, DOI: 10.3894/james.2009.1.2
Abstract: Quasi-geostrophic theory forms the basis for much of our understanding of mid-latitude atmospheric dynamics. The theory is typically presented in either its -plane form or its β-plane form. However, for many applications, including diagnostic use in global climate modeling, a fully spherical version would be most useful. Such a global theory does in fact exist and has for many years, but few in the scientific community seem to have ever been aware of it. In the context of shallow water dynamics, it is shown that the spherical version of quasi-geostrophic theory is easily derived (re-derived) based on a partitioning of the flow between nondivergent and irrotational components, as opposed to a partitioning between geostrophic and ageostrophic components. In this way, the invertibility principle is expressed as a relation between the streamfunction and the potential vorticity, rather than between the geopotential and the potential vorticity. This global theory is then extended by showing that the invertibility principle can be solved analytically using spheroidal harmonic transforms, an advancement that greatly improves the usefulness of this “forgotten” theory. When the governing equation for the time evolution of the potential vorticity is linearized about a state of rest, a simple Rossby-Haurwitz wave dispersion relation is derived and examined. These waves have a horizontal structure described by spheroidal harmonics, and the Rossby-Haurwitz wave frequencies are given in terms of the eigenvalues of the spheroidal harmonic operator. Except for sectoral harmonics with low zonal wavenumber, the quasi-geostrophic Rossby-Haurwitz frequencies agree very well with those calculated from the primitive equations. One of the many possible applications of spherical quasi-geostrophic theory is to the study of quasi-geostrophic turbulence on the sphere. In this context, the theory is used to derive an anisotropic Rhines barrier in three-dimensional wavenumber space.
The Size, Structure and Characteristics of Finland’s ITS Industry  [PDF]
Zulkarnain ., Pekka Levi?kangas
Technology and Investment (TI) , 2012, DOI: 10.4236/ti.2012.33022
Abstract: Intelligent transport systems (ITS) are seen as a high-growth segment within the transport sector, as information and communication technologies (ICT) push their way through different industries. ITS products and services has been developed, and its myriad benefits has been introduced which are promising for new business opportunities and investors. Its economic importance has also been recognised as well and many analyst reports show significant growth projections for the ITS market as a whole. This paper attempts to make the first quantitative and empirical analysis of the ITS industry in Finland. The Finnish ITS market had a significant growth in 2007 but has since then been very slowly been turning upwards from the negative growth observed in 2008 and 2009. The fast growing firms have clearly been showing good growth, whereas the weakest performers seem to have a continuous declining trend. The Finnish ITS supply market had an aggregate turnover of approximately € 300 million and around 1700 employees in 2010.
Design of a Unique Open-Geometry Cylindrical Penning Trap
Michael S. Mehlman,Praveen D. Shidling,Richard S. Behling,Benjamin Fenker,Daniel G. Melconian,Levi Clark
Physics , 2012, DOI: 10.1016/j.nima.2013.02.004
Abstract: The Texas A&M University Penning Trap facility is an upcoming ion trap that will be used to search for possible scalar currents in T=2 superallowed $\beta$-delayed proton decays, which, if found, would be an indication of physics beyond the standard model. In addition, TAMUTRAP will provide a low-energy, point-like source of ions for various other applications at the Cyclotron Institute. The experiment is centered around a unique, compensated cylindrical Penning trap that employs a specially optimized $\mathrm{length}/\mathrm{radius}$ ratio in the electrode structure that is not used by any other facility. This allows the geometry to exhibit an unprecedented 90 mm free radius, which is larger than in any existing trap, while at the same time remaining a tractable overall length. The trap geometry was designed from first principles to be suitable for a wide range of nuclear physics experiments. In particular, the electrode structure is both "tunable" and "orthogonalized", which allows for a near quadrupole electric field at the trap center, a feature necessary for performing precision mass measurements.
Adequate thromboprophylaxis in critically ill patients
Marcel Levi
Critical Care , 2010, DOI: 10.1186/cc8949
Abstract: In this issue of Critical Care, Robinson and colleagues [1] investigate the effect of increasing doses of the low molecular weight (LMW) heparin enoxaparin (commonly used as prophylaxis against venous thromboembolism (VTE)) on systemic heparin concentrations, expressed as anti-factor Xa levels. VTE is a common complication in critically ill patients. Reported rates for deep venous thrombosis in patients admitted to the ICU range from 22 to 80% depending on patient characteristics. Thromboprophylaxis with unfractionated or LMW heparin lowers the risk for deep venous thrombosis by more than 50% [2]. Nevertheless, the risk of VTE in critically ill patients receiving LMW heparin prophylaxis is still much higher than in other patient groups. Amongst several factors that may explain the higher incidence of VTE in critically ill patients, such as full immobilisation or withholding anticoagulant prophylaxis is still much higher than in other patient groups. Amongst several factors that may explain the higher incidence of VTE in critically ill patients, such as full immobilisation or withholding anticoagulant prophylaxis because of a high bleeding risk, it was hypothesized that limited bioavailability (that is, lower plasma anti-factor Xa activity) of subcutaneously administered heparin in those patients with impaired peripheral circulation, due to vasopressor medication to maintain central blood pressure, might be important. Indeed, in a first comparative trial it was shown that critically ill patients on high dose vasopressor medication had much lower anti-factor Xa concentrations after the subcutaneous administration of LMW heparin in comparison with intensive care patients that had lower doses of vasopressor or in comparison with patients in the surgical ward [3]. A subsequent study also found consistently lower anti-factor Xa levels after subcutaneous heparin in critically ill patients [4]. In another similar study, critically ill patients with excessive subcutaneous oe
Treatment with recombinant human activated protein C: one size does not fit all
Marcel Levi
Critical Care , 2011, DOI: 10.1186/cc9375
Abstract: Protein C is a physiological anticoagulant factor and has been implicated in the pathogenesis of sepsis for many years. In the previous issue of Critical Care, Shorr and colleagues [1] add to our knowledge of the role of protein C in sepsis by presenting data from the RESPOND (Research Evaluating Serial Protein C Levels in Severe Sepsis Patients on Drotrecogin Alfa [Activated]) study, which demonstrates that administration of recombinant human activated protein C may modulate protein C levels and thereby potentially affect outcome in patients with severe sepsis. In 40% to 60% of patients with severe sepsis, plasma levels of protein C are low or very low because of impaired synthesis, consumption, and degradation by proteolytic enzymes, such as neutrophil elastase [2,3]. Several studies point to the fact that the plasma level of protein C may be regarded as a strong predictor for the outcome in sepsis, and early improvement in protein C levels strongly correlates with survival [4-6]. Apart from being a relevant biomarker, protein C is likely to be involved in the pathogenesis of sepsis. The most typical example is meningococcal septicemia, in which very low plasma levels of protein C play a pivotal role in the occurrence of purpura fulminans [7]. In addition, transgenic mice show that deficiency of protein C in sepsis is associated with enhanced inflammatory activity [8]. Also, restoration of low protein C levels in septic baboons resulted in an amelioration of coagulopathy and reduced mortality [9]. Hence, there is ample evidence that increasing protein C levels in patients with sepsis could significantly improve clinical outcome.Shorr and colleagues show that the effect of variable dose regimens of recombinant human activated protein C can achieve this therapeutic goal. Patients who were randomly assigned to a strategy in which administration of recombinant human activated protein C was adjusted to their endogenous protein C levels - and who thereby sometimes recei
Antithrombin in sepsis revisited
Marcel Levi
Critical Care , 2005, DOI: 10.1186/cc3819
Abstract: Activation of inflammation and coagulation is important in the pathogenesis of sepsis. Natural anticoagulant pathways have a central position at the crossroads of coagulation and inflammation pathways and the restoration of defective anticoagulant pathways in patients with sepsis has, therefore, received considerable attention. In this issue of Critical Care, Kountchev et al. [1] present some observations that may revive interest in the use of antithrombin concentrate in patients with severe sepsis. They show that six hours after the bolus administration of antithrombin, plasma levels of D-dimer, as a marker for the generation of fibrin, was lower in virtually all patients. These data come on top of recent additional analyses on the use of antithrombin concentrate in patients with severe sepsis and may form a new foundation for the further evaluation of this compound in prospective clinical studies.Antithrombin replacement therapy in patients with severe sepsis and disseminated intravascular coagulation (DIC) has been used since the 1980s. The rationale for this adjunctive treatment strategy is based on the notion that natural anticoagulant pathways are defective in patients with a severe systemic inflammatory response upon infection and that this may play a central role in the systemic generation of thrombin and subsequent formation of microthrombi, which may contribute to the pathogenesis of organ dysfunction [2,3]. Indeed, plasma levels of antithrombin are (very) low in patients with sepsis and are independent predictors of the clinical outcome [4,5]. A substantial drop in the level of circulating antithrombin has been demonstrated to be a very early phenomenon in sepsis, lending support to the idea that this protease inhibitor is involved in the pathogenesis of the disease. In addition, experimental studies suggest that antithrombin may not only have anticoagulant properties, but also may modulate inflammatory responses [6]. Previous studies have shown that the
Obligation and permission when there is a second best and when there is a second worst
An??lisis filos?3fico , 2006,
Abstract: a comparison is made between the criterion of choice of e-admissibility i proposed in levi, 1974 and elaborated in levi, 1980 and 1986, and the ideas about norms elaborated by alchourrón and bulygin (1971 and 1981) with an emphasis on the fact that choice cannot always be evaluated in terms of binary comparisons as the distinction between second worst and not second worst illustrates.
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