639 research outputs found
Letter from F. E. Van Der Veer to John T. Cunningham, 1934-12-04
No full textTyped letter from F.E. Van Der Veer in Atlanta, Georgia to John T. Cunningham in Clarksville, Tennessee. The letter is responding to an inquiry Cunningham made regarding the age of Mary E. Hanratty
Positron emission tomography compartmental models: A basis pursuit strategy for kinetic modelling
No full textA kinetic modelling approach for the quantification of in vivo tracer studies with dynamic positron emission tomography (PET) is presented. The approach is based on a general compartmental description of the tracer’s fate in vivo and determines a parsimonious model consistent with the measured data. The technique involves the determination of a sparse selection of kinetic basis functions from an overcomplete dictionary using the method of basis pursuit denoising. This enables the characterization of the systems impulse response function from which values of the systems macro parameters can be estimated. These parameter estimates can be obtained from a region of interest analysis or as parametric images from a voxel based analysis. In addition, model order estimates are returned which correspond to the number of compartments in the estimated compartmental model. Validation studies evaluate the methods performance against two pre-existing data led techniques, namely graphical analysis and spectral analysis. Application of this technique to measured PET data is demonstrated using [ 11 C]diprenorphine (opiate receptor) and [ 11 C]WAY-100635 (5-HT1A receptor). Whilst, the method is presented in the context of PET neuroreceptor binding studies, it has general applicability to the quantification of PET/SPET radiotracer studies in neurology, oncology and cardiology
Thermal analysis of the Wire and Arc Additive Manufacturing process using the F.E. method
No full textIn this research, a thermal analysis of the wire and arc additive manufacturing process is presented based on the F.E. method. An important quality of the F.E. model that is presented in this research is to describe the temperature field that is experienced by the deposited material in the wire and arc additive manufacturing process. In contrast to the traditional method of monitoring the substrate temperature, the F.E. model allows to describe the temperature field that is experienced by the deposited material constituting both the multilayer weld deposit and the component. Accordingly, the F.E. model is capable to describe the effect of the locally attained temperature field on the microstructure of the deposited material constituting the multilayer weld deposit in terms of the thermal characteristics including the temperature distribution, the locally attained temperature values, the cooling rates and the temperature gradients throughout the component. Two cooling methods are proposed to control the heat dissipation from the component to the environment based on the application of an interlayer waiting time and immersing the component into a cooling medium. The results show a significant effect of the cooling methods on the temperature field that is experienced by the material constituting both the multilayer weld deposit and the component. Indicating that the cooling methods that are proposed in this research are effective to control the microstructure and the temperature field that is experienced by the component in the wire and arc additive manufacturing process. The resulting microstructure is characterised in terms of the microstructural morphology and the microstructural constituents, using optical microscopy based on the average grain size and the distribution of alloying elements throughout the material constituting the multilayer weld deposit. In addition, the average grain size and the distribution of the alloying elements throughout the material are evaluated in terms of the hardness values.Materials Science and Engineerin
Rank-Shaping Regularization of Exponential Spectral Analysis for Application to Functional Parametric Mapping
No full textCompartmental models are widely used for the mathematical modelling of dynamic studies acquired with positron emission tomography (PET). The numerical problem involves the estimation of a sum of decaying real exponentials convolved with an input function. In exponential spectral analysis (SA), the nonlinear estimation of the exponential functions is replaced by the linear estimation of the coefficients of a predefined set of exponential basis functions. This set-up guarantees fast estimation and attainment of the global optimum. SA, however, is hampered by high sensitivity to noise and, because of the positivity constraints implemented in the algorithm, cannot be extended to reference region modelling. In this paper, SA limitations are addressed by a new rank-shaping (RS) estimator that defines an appropriate regularization over an unconstrained least-squares solution obtained through singular value decomposition of the exponential base. Shrinkage parameters are conditioned on the expected signal-to-noise ratio. Through application to simulated and real datasets, it is shown that RS ameliorates and extends SA properties in the case of the production of functional parametric maps from PET studies
PRESENCE AS CYBER-IMMERSION AND INFANTILE LIFEWORLD TRANSITION FACTOR F.E. VASILYUK'S TYPOLOGY
No full textАвтор статьи анализирует психологические аспекты "виртуализации" человека и его бытия в контексте типологии жизненных миров Ф.Е. Василюка. Выдвигается гипотеза о сущностной близости пребывания человека в виртуальном пространстве и нахождения в инфантильном жизненном мире. Автор полагает, что ключевую роль в процессах киберпогружения и перехода в инфантильный жизненный мир может играть нахождение в "состоянии присутствия" как субъективного переживания пребывания в иллюзорном мире, альтернативном реальности.The author analyses psychological aspects of "virtualization" in terms of F.E. Vasilyuk's lifeworlds' typology. The author states that being in the cyberspace is similar to existence in the infantile lifeworld and that the "presence" phenomenon may serve as the key mechanism to cyber-immersion and "slipping" into the infantile lifeworld.111-11
Fairytale Therapy Today: Determining its Boundaries and Content
No full textAbstractPositions existing in psychology in relation to modern fairytale therapy are analyzed while stating the insufficient development of the theoretical basis thereof. Based on F.E. Vasilyuk's ideas on the need to develop a psychotechnical approach, the author believes that fairytale therapy has the features of a psychotechnical system. The article outlines all kinds of approaches to the understanding of the object, methods and essence of fairytale therapy as a special scientific and practical area
The art of scholarly reviewing: Principles and practices
No full textThe quality and reputation of an academic journal can depend on several factors, but high-quality peer reviews are always a core requirement. Unfortunately, reviews are not always up to the standard that they should be. Poor reviews can result in a number of problems including sub-standard articles being accepted and good manuscripts being rejected. Good reviews are comparable to good papers; they require attention and dedication to write well. Although journals are different, it is important that reviewers approach their task with goodwill, i.e. that they approach a manuscript with an open mind, read it with care and attention and make comments that are constructive and show self-reflection. Reviewers need to know the evaluation standards and the limits of their own expertise and, if in doubt, not to be afraid to say so.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Information and Communication Technolog
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