The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
H Partsch - One of the best experts on this subject based on the ideXlab platform.
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narrowing of leg veins under compression demonstrated by magnetic resonance imaging mri
International Angiology, 2010Co-Authors: H Partsch, Giovanni Mosti, F MostiAbstract:Aim The aim of this paper was to demonstrate the usefulness of magnetic resonance imaging (MRI) for detecting the ability of compression material in narrowing superficial and deep veins in the lower extremity. Methods MRI of the legs was performed in one healthy volunteer and in 11 patients with CEAP C2-C4 without and with different kinds of compression devices. The cross section area of superficial and deep veins was measured by planimetry in mid-calf and mid-thigh slices. The interface Pressure of compression was measured at the same level. Results Examples are presented showing that the narrowing of veins does not only depend on the Exerted Pressure but also on the body position and the resulting distortion of the tissue. In the prone and the standing position deep veins may show a greater reduction of the cross section area than in superficial veins. Conclusion MRI is a powerful method to assess venous narrowing by external compression. Especially in the standing position new insights regarding the effects of different compression devices may be expected.
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the static stiffness index a simple method to assess the elastic property of compression material in vivo
Dermatologic Surgery, 2005Co-Authors: H PartschAbstract:BackgroundThe efficacy of compression therapy depends mainly on the Exerted Pressure and on the stiffness of the material.ObjectiveTo propose a simple method by which Pressure and stiffness can be assessed in the individual patient.Material and MethodsUsing a Pressure transducer (Kikuhime small prob
Charles A. Garris - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Flow Around Cone-Vane Configurations for a Novel Crypto-Steady Pressure Exchange Ejector System
ASME 2009 3rd International Conference on Energy Sustainability Volume 1, 2009Co-Authors: Kartik V Bulusu, Charles A. GarrisAbstract:A novel ejector based on the concept of supersonic crypto-steady Pressure exchange rather than the more energy dissipative turbulent entrainment phenomenon is being developed. Crypto-steady flow is one in which, the flow is steady in a certain moving frame of reference, but is non-steady relative to the laboratory. The process of Pressure exchange occurs where flows exchange mechanical energy through work of mutually Exerted Pressure forces at their interfaces. Such an ejector would have higher efficiency and environmental benefits. It has been envisioned that crypto-steady Pressure-exchange can be obtained by the use of a free spinning rotor (cone-vane configuration) having canted jets of primary fluid. The resolution of the flow structure with emphasis on shock and expansion waves and mixing between primary and secondary fluids is being considered under certain rotor configurations. A single component Laser Doppler Velocimeter (LDV) system has been employed in studying the interaction between the supersonic primary jet, and the entrained subsonic secondary jet under nonrotating rotor conditions. The data reduction of measurements is being performed using a simple signal conditioning and data analysis algorithm executed in real time with a digital oscilloscope and in parallel, with a more advanced frequency tracking flow processor. Crypto-steady Pressure-exchange has the potential of providing society with a highly efficient means of compressing a low energy fluid through direct contact with a relatively high energy fluid. An experimental framework for investigating the process of Pressure exchange is reported and a hypothesis for pseudoblade formation is also established.
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Supersonic Flow Visualization Over Patented Rotors for a Novel Crypto-Steady Pressure Exchange Ejector Using Schlieren Photography
Volume 6: Emerging Technologies: Alternative Energy Systems; Energy Systems: Analysis Thermodynamics and Sustainability, 2009Co-Authors: Kartik V Bulusu, Charles A. GarrisAbstract:The process of Pressure exchange occurs where flows exchange mechanical energy through work of mutually Exerted Pressure forces at their interfaces. A novel ejector based on the concept of supersonic crypto-steady Pressure exchange rather than the more energy dissipative turbulent entrainment phenomenon is being developed. To better understand the flow structures in context of the novel ejector, schlieren photography is being used as a flow visualizaton tool. The crypto-steady mode of Pressure exchange can be achieved with rotors that enable the creating of psuedoblades and entrainment gullies by a primary supersonic fluid. The primary fluid can perform work on an entrained subsonic secondary fluid in a non-steady mode of fluid-fluid interaction. The primary fluid jets emanating from the rotor form a helical pattern whereby the secondary fluid becomes entrapped in the interstices of the helices. In the non-rotating case of the rotors, the voids between psuedoblades that create helical structure end up, providing entrainment gullies for the secondary fluid. In the rotating case, work is done by the expanding primary fluid on the secondary fluid by the Pressure forces acting across the helical boundary between the two fluids. Crypto-steady Pressure-exchange has the potential of providing society with a highly efficient means of compressing a low energy fluid through direct contact with a relatively high energy fluid, thereby circumventing the complexity and the energy dissipation associated with intervening machinery inherent in conventional compressors and turbulent mixing in ejectors. Global entropy can be calculated using steady inviscid two dimensional equations. The paper will report progress made by using schlieren photography on three patented rotors.Copyright © 2009 by ASME
Mariachiara Zanetti - One of the best experts on this subject based on the ideXlab platform.
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Anaerobic digestion of extruded OFMSW
Bioresource Technology, 2011Co-Authors: Daniel Novarino, Mariachiara ZanettiAbstract:Abstract Organic fraction of municipal solid waste (OFMSW) was used to feed two pilot plants of 1000 l working in anaerobic conditions. The OFMSW had previously been treated using a system of extrusion which, due to Exerted Pressure, separates the undesired fractions of waste from organic waste and reduces the organic fraction in a kind of homogeneous jam. Pilot tests were performed in semi-continuous conditions with a stepwise progressive increase of the total solids content (TS) of the input material from 3% TS w/w (1.5 g VS l −1 d −1 organic loading rate) to 10% TS w/w (4.3 g VS l −1 d −1 organic loading rate) using activated sludge as diluting agent. The average specific biogas production obtained was 600 l kg −1 VS. When the input TS content was increased to 10% w/w, the biogas average specific production went up to 800 l kg −1 VS. The methane content in the biogas was always higher than 60% measured by volume.
Marion Nestle - One of the best experts on this subject based on the ideXlab platform.
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Do Dietary Guidelines Explain the Obesity Epidemic
American Journal of Preventive Medicine, 2008Co-Authors: Steven H Woolf, Marion NestleAbstract:Two decades ago, the movements known as evidence-based medicine and evidence-based public health arose out of concerns that the road to bad interventions is paved with good intentions, which sometimes result in more harm than good. Since then, both medicine and public health have critiqued scientific evidence more carefully and weighed benefits against harms before making recommendations to practitioners and the public. This analytic rigor is reflected in the work of groups such as the U.S. Preventive Services Task Force (USPTSF) and the Task Force on Community Preventive Services. Attention to the same concerns has long been evident in the development of dietary guidelines. For decades, researchers, clinicians, and policymakers have considered the potential harms, along with the benefits, of advocating changes in the diet. The need for a systematic review of these issues was explicit as long ago as the late 1980s, when the Surgeon General’s Report on Nutrition and Health and the National Research Council’s Diet and Health reports together devoted more than 1400 pages to meticulous analyses of the scientific evidence supporting each recommendation and to cautious, nuanced critiques of the quality and limitations of the data. Today’s readers enjoy access to an extensive literature regarding the potential harms of dietary modifications, of dietary guidelines, and of practice guidelines in general. Science is not the only consideration in developing dietary guidelines, however. Government agencies and the constituents they serve invariably bring an agenda to statements of nutrition advice. Dietary guidelines have implications at every level of government, from federal agencies such as the U.S. Department of Agriculture (USDA) to the local school board. In the private sector, the food industry, ranchers, restaurateurs, and beverage producers—along with their lobbyists—have famously Exerted Pressure to eliminate or soften language in the guidelines that might harm commercial interests. Accommodating the realities of public acceptance has also been a factor, as when the best advice based on science was considered too unrealistic for widespread adoption. The critical appraisal of nutrition research is inherently challenging, perhaps moreso than in other areas of public health or medicine. The time needed to measure meaningful health outcomes is so long that studies often must rely on questionable surrogate measures. Almost every study is complicated by the enigma of whether foods, some combination of their nutrients, or interactions between foods and other covariates are responsible for observed outcomes. Randomized trials are challenging, not least because of the inherent difficulty of controlling and measuring subjects’ diets and the prohibitive costs and logistic challenges of measuring long-term outcomes. Interventions and outcomes in diet research may be nebulously defined. Even the best dietary trials lack the crisp adherence and evidentiary strength of gold standard efficacy trials of drugs and medical devices. Nutrition research has had its share of “flip-flops” in which dietary practices and nutrients that were supposedly healthful were ultimately shown to offer little benefit or to cause harm (e.g., beta-carotene). Given such difficulties, whether the evidence is good enough to recommend population-based dietary changes comes down to a matter of subjective judgment. Despite these challenges and the enduring Pressure of special interests, what is most striking is that for nearly half a century almost every authoritative government or professional committee that has reviewed research on diet and chronic disease ultimately has arrived at the same basic dietary advice: eat less; move more; eat more fruits, vegetables, and whole grains; and avoid junk food. One need not know the data to infer from the consistency itself and from the number and quality of expert panels over these years that the scientific evidence must be compelling. Against this backdrop appears an article in this issue of the American Journal of Preventive Medicine, in which Marantz et al. discuss the potential harm of dietary guidelines in general and of advice about dietary fat in particular. Although the authors give little attribution to the extensive prior writing on this topic, they do invoke many of the themes we have just mentioned and with which we agree. We strongly disagree, however, with their depiction of how the guidelines were developed, their characterization of the evidence on which the guidelines were based, and their indictment of public health guidance in general. Department of Family Medicine, Virginia Commonwealth University (Woolf), Richmond, Virginia; Department of Nutrition, Food Studies, and Public Health, New York University (Nestle), New York, New York Address correspondence and reprint requests to: Steven H. Woolf, MD, MPH, Department of Family Medicine, Virginia Commonwealth University, West Hospital, 1200 East Broad Street, P.O. Box 980251, Richmond VA 23298-0251. E-mail: swoolf@vcu.edu.
J. Rieneke C. Schreinemakers - One of the best experts on this subject based on the ideXlab platform.
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Pressure effects on the nose by an in-flight oxygen mask during simulated flight conditions
Journal of the Royal Army Medical Corps, 2015Co-Authors: J. Rieneke C. Schreinemakers, Christa Boer, P.c.g.m. Van AmerongenAbstract:Background Dutch F-16 fighter pilots experience oxygen mask inflicted nasal trauma, including discomfort, pain, skin abrasions, bruises and bone remodelling. Pressure and shear forces on the nose might contribute to causing these adverse effects. In this study, it was evaluated how flight conditions affected the Exerted Pressure, and whether shear forces were present. Methods The Pressure Exerted by the oxygen mask was measured in 20 volunteers by placing Pressure sensors on the nose and chin underneath the mask. In the human centrifuge, the effects on the Exerted Pressure during different flight conditions were evaluated (+3Gz, +6Gz, +9Gz, protocolised head movements, mounted visor or night vision goggles, NVG). The runs were recorded to evaluate if the mask9s position changed during the run, which would confirm the presence of shear forces. Results Head movements increased the median Pressure on the nose by 50 mm Hg and on the chin by 37 mm Hg. NVG, a visor and accelerative forces also increased the median Pressure on the nose. Pressure drops on the nose were also observed, during mounted NVG (−63 mm Hg). The recordings showed the mask slid downwards, especially during the acceleration phase of the centrifuge run, signifying the presence of shear forces. Conclusions The Exerted Pressure by the oxygen mask changes during different flight conditions. Exposure to changing Pressures and to shear forces probably contributes to mask-inflicted nasal trauma.
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Analysis of oxygen mask-induced soft tissue and nasal bone problems in F-16 pilots
2014Co-Authors: J. Rieneke C. SchreinemakersAbstract:In the present dissertation we investigated the effect of in-flight oxygen masks on the noses of Royal Netherlands Air Force (RNLAF) F-16 pilots. We explained the use of an in-flight oxygen mask by RNLAF F-16 pilots, and presented the medical complaints associated with its usage and related to the nose. The pathophysiology and prevention of similar symptoms observed in athletes were discussed to help explain the pathophysiology of the oxygen mask-induced symptoms. In a review of the literature the pathophysiology of the adaptive response of the nasal bone to the Exerted contact Pressure and friction by the oxygen mask was discussed. The adaptive response of the nasal bone consists of forming new bone. Via mechanotransduction a biochemical response is mounted by the nasal bone. Intermittent dynamic mechanical loading with recovery periods generates a much stronger bone formation response than one continuous loading period. An analysis of the fit of the oxygen mask demonstrated that a suboptimal fit of the oxygen mask was regarded as a potential contributing factor to inflicting the symptoms of the nose. A 3D analysis of the fit of the oxygen mask allowed us to evaluate how closely the oxygen mask fit the face. As the main finding we observed that there was space for movement in the nasal area. In-flight displacement may result in exertion of excessive Pressure and friction on the nose. The findings of a cross-sectional questionnaire among the RNLAF F-16 pilots and a prospective post-flight pain score study were presented. It allowed us to make an inventory of the symptoms and revealed which conditions worsened and lessened the symptoms according to the pilots. We objectified the latter findings by prospectively collecting pain scores after each flight for several months in a row both in The Netherlands and in operational theater. The conditions that were reported to worsen the symptoms correlated to certain types of missions that received high pain scores. In a pilot it was evaluated how much Pressure the oxygen mask Exerted during static conditions. The Pressure was measured on the nose and chin when the oxygen mask and the helmet were donned. The baseline Exerted Pressure was compared to the Exerted Pressure while the pilot made protocolized head movements. In a subsequent study, the effect of dynamic conditions on the Exerted contact Pressure on the nose were obtained in the human centrifuge. The Pressure changes on the nose were higher than on the chin. Another main finding was that shear stress and friction were present: during the acceleration phase the mask moved. This chapter demonstrated that Pressure and friction are Exerted chronically. To conclude, the main conclusions of the thesis and strategies for future preventive measures were discussed.
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Exerted Pressure by an in-flight oxygen mask.
Aviation Space and Environmental Medicine, 2014Co-Authors: J. Rieneke C. Schreinemakers, Christa Boer, P.c.g.m. Van AmerongenAbstract:BACKGROUND: F-16 pilots wear an in-flight oxygen mask to prevent hypoxemia. In the contact area with the mask, the pilots experience nasal discomfort and pain, and may even develop nasal deformities. A likely cause is the Pressure Exerted by the mask. In this study the hypothesis was that the change in Pressure Exerted on the nose would be higher than on the chin, an area free of symptoms. METHODS: Six F-16 pilots and five healthy former F-16 pilots volunteered to participate in this observational pilot study. At baseline the pilots donned mask and helmet. The median delta Pressure (deltap) recordings at baseline were compared to the Exerted deltap during the experimental head movements. RESULTS: At baseline, there was no significant difference between the median deltap on the nose and chin (2 vs. 1.6 mmHg, T = 2). Head movements increased the median deltap on the nose by 50 mmHg (T = 0) and on the chin by 31 mmHg (T = 0) when compared to baseline. Head movements also decreased the Pressure by -20 mmHg (T = 1.75) on the nose and -11 mmHg (T = 0) on the chin. CONCLUSIONS: The data show that the baseline deltap is higher on the nose than on the chin. The head movements both increased and decreased the Exerted Pressure on the nose and the chin. These observations suggest that further evaluation of the effect of flight conditions on the Exerted Pressure is worthwhile to understand its contribution to the nasal symptoms.