Download or read book Sources optiques fibr es pour applications biom dicales written by Charles-Henri Hage and published by . This book was released on 2013 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ce mémoire présente les travaux effectués sur le développement d'une source optique servant à des applications d'imagerie biomédicale en général et de diffusion Raman cohérente en particulier. En effet la diffusion de ces dernières est freinée par le verrou technologique que constitue la nécessité de deux impulsions synchronisées et décalées en longueur d’onde. La praticité et les possibilités de conversions de fréquences offertes par l’optique non-linéaire fibrée sont ainsi utilisées pour adresser ce verrou technologique. Tout d’abord, une source simplement réglable en longueur d’onde est générée par l’effet d’auto-décalage en fréquence optique d'un soliton par effet Raman. Une étude des principaux paramètres de fibre aboutit à des décalages de 320 à plus de 500 nm, permettant une imagerie des résonances d’intérêt (≈ 1000-4000 cm-1). Deux applications de ce décalage sont présentées. Ensuite, l’autre impulsion voit sa largeur spectrale réduite de 70 à 10 cm-1 par compression spectrale, qui consiste en un "regroupement non-linéaire de fréquences sans pertes", afin de bénéficier de la résolution spectrale nécessaire. Enfin, la source développée est validée par l’acquisition de spectres CARS de différents échantillons de référence, pour différentes résonances (850 à 1750 cm-1). Une extension de la source à d'autres types d'imagerie est proposée, ainsi qu'une architecture de source quasiment entièrement fibrée exploitant les principes développés au cours de cette thèse

Download or read book Basic Technics in Ecological Farming Techniques de Base en Agriculture Biologique Grunds tzliche Verfahren der kologischen Landwirtschaft Le Maintien de la Fertilit des Sols The Maintenance of Soil Fertility Die Erhaltung der Bodenfruchtbarkeit written by Stuart Hill and published by Birkhäuser. This book was released on 2013-12-14 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Libraries of the United States and Canada written by American Library Association and published by . This book was released on 1918 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Bibliography of Fishes written by Bashford Dean and published by . This book was released on 1916 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dictionnaire des termes de m decine written by Henry Eugène de Méric and published by . This book was released on 1899 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gait Analysis in the Science of Rehabilitation written by Joel A. DeLisa and published by DIANE Publishing. This book was released on 1998 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Instrumented gait analysis systems offer objective evaluation of the effectiveness of the various rehabilitation treatments that are aimed at improving gait disabilities. There are four sections in this report: clinical observation; review of the instrumental gait analysis systems; the value of information resulting from instrumented gait analysis from the perspective of a psychiatrist, an orthopedic surgeon, & a physical therapist; & discussion of future trends for gait laboratories. The authors are experts from multiple rehabilitation specialties to give you an understanding of how gait analysis can be used to evaluate a person's walking abilities to maximize function & maintain or improve quality of life. Illustrations.

Download or read book Radioluminescence written by Jan Lindström and published by Linköping University Electronic Press. This book was released on 2021-03-24 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: A phosphor or scintillator is a material that will emit visible light when struck by ionising radiation. In the early days of diagnostic radiology, it was discovered that the radiation dose needed to get an image on a film, could be greatly reduced by inserting a fluorescent layer of a phosphor in direct contact with the film. Thus, introducing the step of converting the ionising radiation to light in a first step. Going forward in time, film has been replaced with photodetectors and there is now a variety of imaging x-ray systems, still based on phosphors and scintillators. There is continuous research going on to optimise between the radiation dose needed and a sufficient image quality. These factors tend to be in opposition to each other. It is a complicated task to optimise these imaging system and new phosphor materials emerges regularly. One of the key factors is the efficiency of the conversion from xrays to light. In this work this is denoted “extrinsic efficiency”. It is important since it largely determines the final dose to the patient needed for the imaging task. Most imaging x-ray detectors are based on phosphor or scintillator types where their imaging performance has been improved through tweaking of various parameters (light guide structure, higher density, light emission spectrum matching to photodetectors, delayed fluorescence quenching etc) One key factor that largely determines the extrinsic efficiency of a specific phosphor is the particle size. Larger particles result in a higher luminance of the phosphor for the same radiation dose as does as a thicker phosphor layer (to a limit). There exists already a battery of models describing various phosphor qualities. However, particle size and thickness have not been treated as a fully independent variables in previous model works. Indirectly, the influence of these parameters is accounted for, but the existing models were either considered too general, containing several complex parameters and factors to cover all kind of cases or too highly specialised to be easily applicable to fluorescent detectors in diagnostic radiology. The aim of this thesis is therefore to describe and assess a simple model denoted the “LAC-model” (after the original authors Lindström and Alm Carlsson), developed for a fluorescent layer using individual sub-layers defined by the particle size diameter. The model is thought to be a tool for quickly evaluating various particle size and fluorescent layer thickness combinations for a chosen phosphor and design. It may also serve as a more intuitive description of the underlying parameters influencing the final extrinsic efficiency. Further tests affirmed the validity of the model through measurements. The LACmodel produced results deviating a maximum of +5 % from luminescence measurements. During the development of the model various assumptions and simplifications were made. One assumption was the absence of a so called “dead layer”. This is a layer supposedly surrounding each particle decreasing the efficiency of converting x-rays to light. It is not completely “dead” as in inactive but is thought to have a reduced efficiency. This phenomenon was struggled with, when historically designing electron beam stimulated phosphors for various applications (i.e. displays, TV tubes etc). There are also articles reporting dead layer influence for x-ray detectors (usually spectrometers i.e. not for imaging). By introducing a dead layer in the LAC-model the effect of the layer was investigated and was found to result in a change of less than 8% for the extrinsic efficiency. It was also noted that sometimes a dead layer effect may emerge at surfaces of a scintillator slab but not necessarily connected to the phosphor particles themselves. Due to differences between phosphor material and the surroundings, an interface effect arose to compete with the process of inherent dead layers of the individual particles. It was found to be mostly negligible for x-rays in the studied energy and material range. However, an effect was shown for electrons as incident ionising radiation which could shed some light on the strangely neglected apparent dead layer created this way. Finally, applications, one involving developing a prototype for checking the light field radiation field coincidence, were evaluated for overall performance and the optimisation level of the applied fluorescent layer. Interesting findings were made during the development process: for the first time to the knowledge of the author, focus shift wandering was quantified in the corresponding movement of the x-ray field edge and a non-trivial discussion on the concept of an apparent light field edge resulted in a modified definition of the same. En fosfor eller scintillator är ett material som avger synligt ljus när det träffas av joniserande strålning. Inom diagnostisk radiologi upptäckte man i ett tidigt skede att stråldosen som behövdes för att få en bild på en röntgenfilm, reducerades kraftigt om man placerade ett fluorescerande skikt, en fosfor, i direkt kontakt med filmen. I nutid har film ersatts med fotodetektorer och det finns nu en mängd olika röntgenbildsystem men som fortfarande är baserade på fosforer och scintillatorer. Det pågår en kontinuerlig forskning för att optimera mellan erforderlig stråldos och en tillräcklig god diagnostisk bildkvalitet. Dessa faktorer tenderar att motverka varandra. Det är en komplicerad uppgift att optimera röntgenbildsystemen och nya fosformaterial dyker ständigt upp. En av de viktiga egenskaperna är fosforns omvandlingseffektivitet från röntgen till ljus. I detta arbete används benämningen ”extrinsisk (yttre) effektivitet". Denna egenskap är viktig eftersom den i stor utsträckning bestämmer den slutliga dosen till patienten som krävs för bilddiagnostiken. De flesta röntgendetektorer är baserade på fosfor- eller scintillatortyper där bildprestanda har förbättrats genom att utveckla olika parametrar (ljusledarstruktur, högre densitet, ljusemissionsspektrum som matchar fotodetektorer, minskad efterlysning etc.). En viktig faktor som i stor utsträckning bestämmer omvandlingseffektiviteten hos en specifik fosfor är partikelstorleken. Större partiklar resulterar i en högre luminescens (mer ljus) från fosforen för samma stråldos. Vilket också gäller för ett tjockare fosforlager (till en viss gräns!). Det finns redan fysikaliska modeller som beskriver olika fosforparametrar men partikelstorlek och fosfortjocklek har dock inte hanterats som fristående variabler i dessa modellarbeten. Istället har deras inverkan modellerats indirekt men det har gjort att de befintliga modellerna kan anses komplexa. De är antingen för generella som medför flera komplexa parametrar och faktorer för att täcka alla tänkbara varianter eller för specialiserade för att kunna tillämpas enkelt på fluorescerande detektorer i diagnostisk radiologi. Syftet med denna avhandling är därför att beskriva och analysera en praktisk modell betecknad ”LAC-modellen” (efter de ursprungliga författarna Lindström och Alm Carlsson). Den är utvecklad för ett fluorescerande block som består av flera underliggande skikt vars tjocklek bestäms av partiklarnas diameter. Avsikten med modellen är att den ska vara ett verktyg för att snabbt utvärdera olika varianter av partikelstorlek och tjockleks-kombinationer för en vald fosfor med i grunden samma design. Experiment har bekräftat modellens giltighet och mätresultat visar att modellresultaten avvek maximalt +5% från luminiscensmätningar. Utvecklingen av modellen krävde olika antaganden och förenklingar. Ett antagande var frånvaron av ett så kallat ”dött lager”. Det är ett skikt som antas omge varje partikel och som därför minskar omvandlingseffektiviteten från röntgen till ljus. Det är dock inte helt "dött" i meningen helt inaktivt men har en mindre förmåga att omvandla röntgen till ljus jämfört med fosforns huvudmaterial. Historisk sett har man försökt åtgärda detta fenomen under lång tid och speciellt för applikationer där man använt sig av elektronstrålar (dvs olika typer av displayer, TV-rör etc.). Just för elektroner har man sett att döda skiktet tenderar att växa med tiden. Det finns också artiklar som rapporterar en påverkan av röntgendetektorers funktion (vanligtvis dock för spektrometrar, dvs inte för avbildning). Genom att införa ett dött skikt i LAC-modellen undersöktes skiktets effekt och visade sig resultera i en förändring på mindre än 8% för effektiviteten. Det noterades också att ibland kan en dödskiktsliknande effekt uppstå vid ytor av ett scintillatorblock men inte nödvändigtvis pga. av själva fosforpartiklarnas ljusomvandlingsegenskaper. Då det uppstår skillnader mellan fosformaterialet och omgivningen får man en s.k. gränsskiktseffekt som s.a.s. konkurrerar med kemiskt döda skiktet på de enskilda partiklarna. De döda skiktens inverkan visade sig i princip försumbara för röntgenbild-detektorer - åtminstone inom det studerade energi- och materialområdet. En tydlig effekt kunde dock noteras för joniserande strålning i form av elektroner. Simuleringarna kunde ge en bättre bild av egenskaperna hos det döda skiktet som skapats på detta sätt. Slutligen utvärderades två applikationer med hjälp av LAC-modellen: en prototyp för kontroll av ljusfältets och strålfältets överenstämmelse i läge och position. Samt en etablerad produkt med samma användningsområde. I båda fallen undersöktes det fluorescerande skiktets optimeringsgrad. Intressanta resultat noterades under utvecklingsprocessen av prototypen: för första gången, så vitt författaren vet, kunde man kvantifiera röntgenrörs s.k. fokusvandring.

Download or read book Life Atomic written by Angela N. H. Creager and published by University of Chicago Press. This book was released on 2013-10-02 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: After World War II, the US Atomic Energy Commission (AEC) began mass-producing radioisotopes, sending out nearly 64,000 shipments of radioactive materials to scientists and physicians by 1955. Even as the atomic bomb became the focus of Cold War anxiety, radioisotopes represented the government’s efforts to harness the power of the atom for peace—advancing medicine, domestic energy, and foreign relations. In Life Atomic, Angela N. H. Creager tells the story of how these radioisotopes, which were simultaneously scientific tools and political icons, transformed biomedicine and ecology. Government-produced radioisotopes provided physicians with new tools for diagnosis and therapy, specifically cancer therapy, and enabled biologists to trace molecular transformations. Yet the government’s attempt to present radioisotopes as marvelous dividends of the atomic age was undercut in the 1950s by the fallout debates, as scientists and citizens recognized the hazards of low-level radiation. Creager reveals that growing consciousness of the danger of radioactivity did not reduce the demand for radioisotopes at hospitals and laboratories, but it did change their popular representation from a therapeutic agent to an environmental poison. She then demonstrates how, by the late twentieth century, public fear of radioactivity overshadowed any appreciation of the positive consequences of the AEC’s provision of radioisotopes for research and medicine.

Download or read book A Dictionary of Medical Science written by Robley Dunglison and published by . This book was released on 1857 with total page 998 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book COSATI Subject Category List written by Federal Council for Science and Technology (U.S.). Committee on Scientific and Technical Information and published by . This book was released on 1964 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Velocity Impact Dynamics written by Jonas A. Zukas and published by Wiley-Interscience. This book was released on 1990-11-08 with total page 968 pages. Available in PDF, EPUB and Kindle. Book excerpt: This compendium of mathematical techniques for the modeling and simulation of high-velocity impacts presents the various analytical and experimental aspects of impact dynamics and describes the responses of a variety of materials and structures under impact. Coverage is extended beyond that of the author's Impact Dynamics and deals with new topics in impacts involving inert materials, including the dynamic response to energetic and inert materials. Treatment uses classical mechanics along with the conservation laws, combined with failure analysis.

Download or read book Clinical Biomechanics of the Lower Extremities written by Ronald L. Valmassy and published by . This book was released on 1996 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: CLINICAL BIOMECHANICS OF THE LOWER EXTREMITY is a comprehensive text addressing the principles of anatomic and biomechanical development and the clinical application of these principles to disease/disorder management. The emphasis of the book is on practical information applicable to the daily practice of lower extremity care. Topics covered include: the physical examination and the assessment of disorders having a biomechanical basis, casting techniques, prescription writing, orthotic trouble-shooting, splinting and shoe prescription for athletic activity.

Download or read book Bulletin of the Battle Creek Sanitarium and Hospital Clinic written by Battle Creek Sanitarium (Battle Creek, Mich.) and published by . This book was released on 1925 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Confronting Poverty in Iraq written by World Bank and published by World Bank Publications. This book was released on 2011-01-10 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report provides the most comprehensive and rigorous analysis of Iraqi income and expenditure in several decades. The report makes extensive use of the Iraq Household Socio-Economic Survey, the first nationwide income and expenditure survey since 1988. IHSES data is complemented income and expenditure data from a wide range of other measures of living standards, allowing us to analyze living standards in a holistic way. The analysis presented here was performed with two main goals first, to inform the Government s Poverty Reduction Strategy; and second, to serve as a baseline for future assessments of changes in living standards and the identification of critical issues for deeper examination. Iraqi living standards have two unusual characteristics. First, they have fallen over the past generation. Second, they feature surprisingly little inequality. These characteristics are both rooted in Iraq s recent history of authoritarian government, war, military occupation, insurgency, and civil strife leading to infrastructure destruction and population displacement. There have been few opportunities for individuals to prosper from professional or entrepreneurial activities. Decades of neglected investment have resulted in deterioration of social services and economic infrastructure. Consequently, individuals have lacked capabilities to prosper and an investment climate conducive to prosperity. School enrollment and life expectancy have declined. Extremely low returns to education reflect the combination of poor educational quality and lack of employment opportunities. In terms of economic infrastructure, access to reliable electricity and water, and even access to paved roads are low, are further reflections of decades of neglect. While the upper end of the distribution has been pulled down by a lack of opportunities, the lower end has been supported by direct government provision of food. The Public Distribution System (PDS) provides 85 percent of food needs. While PDS has been useful as a safety net for the poor and the vulnerable, the system is expensive, inefficient, and fiscally risky. Indeed, PDS food rations account for a far greater share of public spending than does education or health. Going forward, Iraq faces two main challenges. First, although Iraq does not have to develop from scratch, it faces a formidable challenge in re-development. Second, a shift by the Government is required from direct provision of basic subsistence toward investment in human capacities. The Government can provide an enabling environment through investments in economic infrastructure and services to business and citizens, thus allowing the population to make productive use of education and their own labor. Both challenges are now being taken up by the Poverty Reduction Strategy, which articulates a detailed set of required actions and outlines priorities for government spending.

Download or read book Pocket Podiatry written by Angela Evans and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In Sight of Chaos written by Hermann Hesse and published by . This book was released on 1923 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Textbook of Nuclear Medicine written by Michael Andrew Wilson and published by Raven Press. This book was released on 1998 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topics incl. pediatrics bone densitometry nonthyroid endocrine fundamentals of nuclear medicine protocols etc.