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Molecular Descriptors for Natural Diamondoid Hydrocarbons and Quantitative Structure-Property Relationships for Their Chromatographic Data
Alexandru T. Balaban, Douglas J. Klein, Jeremy E. Dahl and Robert M. K. Carlson
The Open Organic Chemistry Journal , 2007, DOI: 10.2174/1874095200701010013]
Abstract: Diamond hydrocarbons (or diamondoids) are hydrocarbons that have a carbon skeleton superimposable on the diamond lattice and contain one or more adamantane units. Recently it was found that many higher diamondoids (containing four to eleven adamantane units) are present in petroleum and can be isolated by a series of methods that include HPLC and GC techniques. We develop QSPR equations using molecular descriptors derived from the topology and geometry of diamondoids, by means of dualist graphs consisting of vertices placed at the centers of adamantane cells forming the diamondoid, and of edges connecting vertices centered in adamantane cells sharing faces. From distance (or distancedistance) matrices encoding the topology and geometry of diamondoids one can obtain distance sums, distance-distance sums, or eigenvectors as molecular descriptors characterizing the diamondoids. These descriptors afford satisfactory correlations with GC and HPLC retention data, and may also facilitate the identification of diamondoid isomers.
Assessing the Outcome of Teacher Education Programs in Norway: An Analysis and Discussion of the Factor Structure in Domains of Teacher Practicum for Student Teachers at Three Norwegian Universities  [PDF]
Trond Solhaug, Thomas Dahl
Creative Education (CE) , 2016, DOI: 10.4236/ce.2016.710157
Abstract: This article contributes to our understanding of teacher education by presenting the results of a large pilot study of quality assessments of teacher education programs at three Norwegian universities. We present an assessment instrument that corresponds to the California Standards for Teaching Professions and the practice domains developed by Darling-Hammond. The research question is: To what extent does the reported five-factor structure in the reported revised instrument (Darling-Hammond) fit the Norwegian context? We have revised this instrument to better cover both the documented dimensions of teacher professionalism and the demands regarding teacher quality in Norwegian educational policy. This has been accomplished by incorporating and modifying the items of the Darling-Hammond instrument. The modification process involved a selection of students, teachers, teacher educators and a school headmaster who discussed the relevance and content validity of the items. The final questionnaire was piloted at three Norwegian universities in three different education programs, with the participation of 419 students. The results show high inter-correlation between the original practice domains of Darling-Hammond, but the original factor structure is reproduced and to some extent supported. The results are discussed, and we conclude that the reported assessment instrument is valid as a measure of the teacher education program contributions to students’ competence in the five reported domains of the teacher practicum. Therefore, the instrument may be used as an overall evaluation of the complete program or may be slightly modified using the item format to assess distinct aspects of teacher education.
Disruption of Mycobacterium smegmatis Biofilms Using Bacteriophages Alone or in Combination with Mechanical Stress  [PDF]
Brendan Kiefer, John L. Dahl
Advances in Microbiology (AiM) , 2015, DOI: 10.4236/aim.2015.510073
Abstract: Environmental mycobacteria are capable of forming biofilms in low-nutrient environments, and these biofilms may act as reservoirs for opportunistic infections. The purpose of this study was to determine if bacteriophages could disrupt existing biofilms of acid-fast staining Mycobacterium smegmatis. Using the MBEC 96-well plastic peg assay system, M. smegmatis biofilms were created and then tested for their stability in the presence of mycobacteriophages isolated from a Minnesota sphagnum peat bog. All phages tested were lytic and were observed to have weak, intermediate, and strong abilities to disrupt M. smegmatis biofilms. The formation of biofilms was severely impaired in the presence of mycobacteriophages. Phage treatment was also shown to augment?M. smegmatis biofilm disruption by mechanical forces of sonication or water flow. Our study shows that, as with biofilms of Gram-positive and Gram-negative bacteria, mycobacterial biofilms are also susceptible to destruction by bacteriophages.
New oral antithrombotics: focus on dabigatran, an oral, reversible direct thrombin inhibitor for the prevention and treatment of venous and arterial thromboembolic disorders
Dahl OE
Vascular Health and Risk Management , 2012, DOI: http://dx.doi.org/10.2147/VHRM.S26482
Abstract: ral antithrombotics: focus on dabigatran, an oral, reversible direct thrombin inhibitor for the prevention and treatment of venous and arterial thromboembolic disorders Review (6777) Total Article Views Authors: Dahl OE Published Date January 2012 Volume 2012:8 Pages 45 - 57 DOI: http://dx.doi.org/10.2147/VHRM.S26482 Received: 23 September 2011 Accepted: 07 December 2011 Published: 25 January 2012 Ola E Dahl1,2 1Department of Orthopaedics, Innlandet Hospital Trust, Elverum Central Hospital, Elverum, Norway; 2Thrombosis Research Institute, London, UK Abstract: Venous thromboembolism, presenting as deep vein thrombosis or pulmonary embolism, is a major challenge for health care systems. It is the third most common vascular disease after coronary heart disease and stroke, and many hospitalized patients have at least one risk factor. In particular, patients undergoing hip or knee replacement are at risk, with an incidence of asymptomatic deep vein thrombosis of 40%–60% without thromboprophylaxis. Venous thromboembolism is associated with significant mortality and morbidity, with patients being at risk of recurrence, post-thrombotic syndrome, and chronic thromboembolic pulmonary hypertension. Arterial thromboembolism is even more frequent, and atrial fibrillation, the most common embolic source (cardiac arrhythmia), is associated with a five-fold increase in the risk of stroke. Strokes due to atrial fibrillation tend to be more severe and disabling and are more often fatal than strokes due to other causes. Currently, recommended management of both venous and arterial thromboembolism involves the use of anticoagulants such as coumarin and heparin derivatives. These agents are effective, although have characteristics that prevent them from providing optimal anticoagulation and convenience. Hence, new improved oral anticoagulants are being investigated. Dabigatran is a reversible, direct thrombin inhibitor, which is administered as dabigatran etexilate, the oral prodrug. Because it is the first new oral anticoagulant that has been licensed in many countries worldwide for thromboprophylaxis following orthopedic surgery and for stroke prevention in patients with atrial fibrillation, this compound will be the main focus of this review. Dabigatran has been investigated for the treatment of established venous thromboembolism and prevention of recurrence in patients undergoing hip or knee replacement, as well as for stroke prevention in atrial fibrillation patients with a moderate and high risk of stroke.
Contact Geometry in Electromagnetism
Matias Dahl
PIER , 2004, DOI: 10.2528/PIER03070801
Abstract: In the first part of this work we show that, by working in Fourier space, the Bohren decomposition and the Helmholtz's decomposition can be combined into one decomposition. This yields a completely mathematical decomposition, which decomposes an arbitrary vector field on a into three components. A key property of the decomposition is that it commutes both with the curl operator and with the time derivative. We can therefore apply this decomposition to Maxwell's equations without assuming anything about the media. As a result, we show that Maxwell's equations split into three completely uncoupled sets of equations. Further, when a medium is introduced, these decomposed Maxwell's equations either remain uncoupled, or become coupled depending on the complexity of the medium. In the second part of this work, we give a short introduction to contact geometry and then study its relation to electromagnetism. By studying examples, we show that the decomposed fields in the decomposed Maxwell's equations always seem to induce contact structures. For instance, for a plane wave, the decomposed fields are the right and left hand circulary polarized components, and each of these induce their own contact structure. Moreover, we show that each contact structure induces its own metric, and the path traversed by the circulary polarized waves seem to coincide with the geodesics of these metrics. This article is an abridged version of the author's master's thesis written under the instruction of Doctor Kirsi Peltonen and under the supervision of Professor Erkki Somersalo.
Electromagnetic Gaussian Beams and Riemannian Geometry
Matias Dahl
PIER , 2006, DOI: 10.2528/PIER05122802
Abstract: A Gaussian beam is an asymptotic solution to Maxwell's equations that propagate along a curve; at each time instant its energy is concentrated around one point on the curve. Such a solution is of the form where is a complex vector field, P >0 is a big constant, and θ is a complex second order polynomial in coordinates adapted to the curve. In recent work by A. P. Kachalov, electromagnetic Gaussian beams have been studied in a geometric setting. Under suitable conditions on the media, a Gaussian beam is determined by Riemann-Finsler geometry depending only on the media. For example, geodesics are admissible curves for Gaussian beams and a curvature equation determines the second order terms in θ. This work begins with a derivation of the geometric equations for Gaussian beams following the work of A. P. Kachalov. The novel feature of this work is that we characterize a class of inhomogeneous anisotropic media where the induced geometry is Riemannian. Namely, if ε, μ are simultaneously diagonalizable with eigenvalues ε, μ , the induced geometry is Riemannian if and only if εμ = εμ for some . What is more, if the latter condition is not met, the geometry is ill-behaved. It is neither smooth nor convex. We also calculate Riemannian metrics for different media. In isotropic media, = εμδ and in more complicated media there are two Riemannian metrics due to different polarizations.
Library Liaison with non-academic units: a new application for a traditional model
Candice Dahl
Partnership : the Canadian Journal of Library and Information Practice and Research , 2007,
Abstract: This paper suggests that traditional models of liaison librarianship, which focuson liaison with academic units such as teaching departments and specificcolleges within institutions, should be adapted and then expanded to include nonacademicunits as well. Although the literature demonstrates that understandingsof liaison work have evolved, it still contains almost no examples of how toextend library liaison beyond traditional academic units in a systematic way. As aresult, existing liaison programs are too narrowly conceived, and the strengths ofthe liaison model are not being fully exploited. By adapting the structures in placeto support traditional liaison, such programs can be expanded to include nonacademicunits as well. As a result, libraries gain opportunities for broadercollaboration on campus. Suggestions for identifying targets for formal nonacademicliaison are provided, as are guidelines for determining suitable liaisonactivities and ensuring administrative support within the library.
Qualitative Film-Analyse: Kulturelle Prozesse im Spiegel des Films Qualitative Analysis of Films: Cultural Processes in the Mirror of Film Análisis cualitativo de la película: Procesos culturales en el espejo del filme
Gloria Dahl
Forum : Qualitative Social Research , 2004,
Abstract: Am Psychologischen Institut der Universit t zu K ln wird seit mehr als 40 Jahren eine spezifische qualitative Form der Film-Analyse, die von Wilhelm SALBER entwickelt wurde, angewandt. Film-Analyse ist dabei nicht Selbstzweck, sondern dient zugleich der Erforschung kultureller Zusammenh nge. Filme erscheinen insofern als Seismografen kultureller Tendenzen, als sie allgemeine Visionen und Bilder zukünftiger Entwicklung zum Ausdruck bringen. Sie zeigen sowohl den Zustand der Gesellschaft in seiner Entstehung und Komplexit t als auch Entwicklungsperspektiven auf, die über Krisen, Verengungen des Spielraums und immanente Selbstheilungskr fte Aufschluss geben. hnlich wie bei der Traumdeutung wird die "manifeste" Film-Erz hlung mit den Einf llen und eingehenden Beschreibungen der Zuschauer in Austausch gebracht, um die "latente" so genannte Komplexentwicklung, den Verlauf psychologischer Entwicklungslinien, zu rekonstruieren. Suspense und das Gefesseltsein der Zuschauer basiert darauf, dass eine bedeutungsvolle Verwandlungserfahrung aktiviert wird – nur Filme, denen es gelingt, solch einen Prozess anzusto en, berühren die Zuschauer. Die psychologische Analyse arbeitet die morphologische Dramaturgie des Filmerlebens heraus, welche in ihrer besonderen dynamischen Figur ausgestaltet wird. Paradoxe unl sbare Problem-Konstellationen sind die treibenden Kr fte in diesem bewegenden Prozess. Die blo e Untersuchung des Drehbuchs oder der Film-Story berücksichtigt nicht, dass der Zuschauer stets Teil der Szene ist. Zuschauer modifizieren die Story in einer charakteristischen Weise, w hrend sie den Film betrachten – entsprechend der Dynamik des psychologischen Prozesses, den sie durchmachen. Ein Zusammenspiel, eine Mischung aus Mitgehen und beobachtender Distanz, welche jeden wirkungsvollen Prozess – sei es in Psychotherapie, Werbung oder Erziehung – kennzeichnet, ist stets am Werk. Da die signifikanten Faktoren unbewusst wirksam sind, ist es notwendig, eine spezifische qualitative Methode anzuwenden, um in der Lage zu sein, diesen vielschichtigen Prozess ad quat zu erfassen. Kurze beispielhafte Analysen der Filme Das Piano, Fight Club, Dogville, Punch-Drunk Love, Catch Me If You Can, The Hours, City of God, Hero und Chihiros Reise ins Zauberland sollen einen Eindruck von der Vorgehensweise geben und demonstrieren, wie qualitative Film-Analyse zum Verstehen kultureller Prozesse beitragen kann. Au erdem wird exemplarisch Einblick in die Arbeit mit M rchenkonstruktionen gegeben. URN: urn:nbn:de:0114-fqs0402271 A special qualitative psychological analysis of movies develop
Stig Hjarvard og Henrik S ndergaard: N rsyn p fjernsyn. Kanal 2 og Weekend-TV
Henrik Dahl
MedieKultur : Journal of Media and Communication Research , 1989,
Danmarks Radio - mellem enhedskultur og pluralisme
Henrik Dahl
MedieKultur : Journal of Media and Communication Research , 1991,
Abstract: Radioen er ikke, hvad den har v ret. Engang var Stadsradiofonien et lands- d kkende monopol med en n sten oph jet kulturel og politisk status. I dag er Danmarks Radio blot ét blandt mange medietilbud, der konsumeres mens vi foretager os alt muligt andet; st r op, k rer bil, spiser og g r i seng. Til geng ld har vi flere radioapparater pr. indbygger og bruger mere tid p radiolytning end nogensinde f r. Mange af radioens fortalere har i dag sv rt ved at v nne sig til dens n- drede status og l nges m ske ubevidst tilbage til dengang, radioen slet og ret konstituerede en landsd kkende kultur og den politiske dagsorden. Henrik Dahl analyserer her vores brug af radioen og hovedtr kkene i vores programm nster fra 20′erne og til idag. Han viser herved dels skiftet i ra- dioens kulturelle funktion og dels de ndrede programm ssige og orga- nisatoriske udfordringer, som denne nye og mere pluralistiske funktion stiller til Danmarks Radio. Hvordan kan organisationen p en gang fast- holde sin genkendelighed, dvs. en kanalidentitet i henholdsvis P1,2 og 3, bevare flertallet af lytterne og politikernes velvilje, og samtidig opret- holde en kulturel profil som public service-institution? - i en tid pr get af lokalradioernes og andre mediers kommercielt betingede konkurrence om lytterne.
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