Projector Model for Efficient List-Mode Reconstruction in PET Scanners with Parallel Planar Detectors

We have developed a new projector model specifically tailored for fast list-mode tomographic reconstructions in Positron emission tomography (PET) scanners with parallel planar detectors. The model provides an accurate estimation of the probability distribution of coincidence events defined by pairs of scintillating crystals. This distribution is parameterized with 2D elliptical Gaussian functions defined in planes perpendicular to the main axis of the tube of response (TOR). The parameters of these Gaussian functions have been obtained by fitting Monte Carlo simulations that include positron range, acolinearity of gamma rays, as well as detector attenuation and scatter effects. The proposed model has been applied efficiently to list-mode reconstruction algorithms. Evaluation with Monte Carlo simulations over a rotating high resolution PET scanner indicates that this model allows to obtain better recovery to noise ratio in OSEM (ordered-subsets, expectation-maximization) reconstruction, if compared to list-mode reconstruction with symmetric circular Gaussian TOR model, and histogram-based OSEM with precalculated system matrix using Monte Carlo simulated models and symmetries.

Tiled Projector Displays Correction for Dark Scenes in Railway Simulators

Tiled projector displays are a common choice for training simulators, where a high resolution output image is required. They are cheap for the resolution that they can reach and can be configured in many different ways. Nevertheless, such kinds of displays require geometric and color correction so that the composite image looks seamless. Display correction is an even bigger challenge when the projected images include dark scenes combined with brighter scenes. This is usually a problem for railway simulators when the train is positioned inside a tunnel and the black offset effect becomes noticeable. In this paper, a method for fast photometric and geometric correction of tiled display systems where dark and bright scenes are combined is presented. The image correction is carried out in two steps. First, geometric alignment and overlapping areas attenuation for brighter scenes is applied. Second, in the event of being inside a tunnel, the brightness of the scene is increased in certain areas using light sources in order to create the impression of darkness but minimizing the effect of the black offset

La integració conceptual o blending i l’arc de Sant Martí: vers una semàntica cognitiva diacrònica i cultural

Aquest article fa un estudi onomasiològic de les denominacions de l’arc de Sant Martí en una perspectiva diacrònica, de contacte de llengües (català, occità, aragonès, etc.) i segons la teoria de la integració conceptual o blending. Planteja la necessitat que la semàntica diacrònica cognitiva faça pròpia l’orientació cultural (fonamentalment, antropològica, històrica social i cultural) i semiòtica.

Blending of industrial waste from different sources as partial substitution of Portland cement in pastes and mortars

Binary and ternary combinations of sewage sludge ash (SSA) with marble dust (MD), fly ash (FA) and rice husk ash (RHA) as replacement in Portland cement pastes, were assessed. Several tests were carried out at different curing ages: thermogravimetry, density, water absorption, ultrasonic pulse velocity and mechanical strengths. Pozzolanic effects of the mineral admixtures, densities similar to control sample and improved absorptions when combining waste materials were identified. In general, the compressive strength reaches or exceeds the cement strength class, and blending SSA, FA and RHA (30% cement replacement) increase of strength by 9%, compared to the control sample, was achieved.

Blending in English Charactoons

This article deals with both the word-formation mechanism of blending and the creative process involved in providing characters with proper names in cartoons or TV series for children in English. The study addresses the nature and features of proper and common names, two apparently well-distinguished categories, as well as, and basically fictional proper names, by suggesting differences between fictional proper names and other types of proper and common names. Furthermore, it discusses the presence of blending in fiction and in fictional proper names, with special reference to charactonyms. The main focus of this work is on blended charactonyms in cartoons addressed to children, which for the purposes of this study will be called cartoonyms or charactoons. Questions such as the following are addressed: the formation or creation of cartoonyms or charactoons from pre-existing material; the semantic motivations behind their formation; their resulting structural complexity; their particularly descriptive, expressive and meaningful nature; as well as how suitable they are to the genre in which they are used.

Water quality effects related to blending waters in distribution systems /

Mode of access: Internet.

Experimentation in the adaptation of the overhead projector utilizing 200 transparencies and 800 overlays in teaching engineering descriptive geometry curricula, June 1, 1959 to August 31, 1960. Final report, grant no. 741023.09, U. S. Office of Education, Dept. of Health, Education, and Welfare.

"Corrected graph iv" leaf inserted.

An account of the isthmus of Tehuantepec in the republic of Mexico; with proposals for establishing a communication between the Atlantic and Pacific oceans, based upon the surveys and reports of a scientific commission, appointed by the projector, Don José de Garay.

Mode of access: Internet.

Coal blending in Illinois /

Project conducted by Energy and Environmental Systems Division of Argonne National Laboratory.

The Projector; a periodical paper, originally published in monthly numbers, from January 1802 to November 1809.

Essays originally published in Gentleman's magazine, in 102 numbers, here reduced to 100.

Experimentation in the adaptation of the overhead projector utilizing 200 transparencies and 800 overlays in teaching engineering descriptive geometry curricula

"Corrected graph iv" leaf inserted.

The Virginia, or Merrimac her real projector.

Mode of access: Internet.

Democracy and assimilation, the blending of immigrant heritages in America.

Bibliography: p. 265-270.

Operator, organizational, field and depot maintenance manual : ground signal projector M1A1, hand pyrotechnic projector M9, and pyrotechnic pistol AN-M8 with pyrotechnic pistol mount M1.

Includes index.

Operator's manual : projector set AN/PFP-1.

"17 October 1960."