Gamma Knife(A (R)) 3-D Dose Distribution Mapping by Magnetic Resonance Imaging

In medical processes where ionizing radiation is used, dose planning and dose delivery are the key elements to patient safety and treatment success, particularly, when the delivered dose in a single session of treatment can be an order of magnitude higher than the regular doses of radiotherapy. Therefore, the radiation dose should be well defined and precisely delivered to the target while minimizing radiation exposure to surrounding normal tissues [1]. Several methods have been proposed to obtain three-dimensional (3-D) dose distribution [2, 3]. In this paper, we propose an alternative method, which can be easily implemented in any stereotactic radiosurgery center with a magnetic resonance imaging (MRI) facility. A phantom with or without scattering centers filled with Fricke gel solution is irradiated with Gamma Knife(A (R)) system at a chosen spot. The phantom can be a replica of a human organ such as head, breast or any other organ. It can even be constructed from a real 3-D MR image of an organ of a patient using a computer-aided construction and irradiated at a specific region corresponding to the tumor position determined by MRI. The spin-lattice relaxation time T (1) of different parts of the irradiated phantom is determined by localized spectroscopy. The T (1)-weighted phantom images are used to correlate the image pixels intensity to the absorbed dose and consequently a 3-D dose distribution with a high resolution is obtained.

Tori embedded in R(3) with dense principal lines

In this paper are given examples of tori T(2) embedded in R(3) with all their principal lines dense. These examples are obtained by stereographic projection of deformations of the Clifford torus in S(3). (C) 2008 Elsevier Masson SAS. All rights reserved.

Block Copolymers Containing (R)-3-Hydroxybutyrate and Isosorbide Succinate or (S)-Lactic Acid Mers

A new aliphatic block copolyester was synthesized in bulk from transesterification techniques between poly((R)-3-hydroxybutyrate) (PHB) and poly(isosorbide succinate) (PIS). Additionally, other two block copolyesters were synthesized in bulk either from transesterification reactions involving PHB and poly(l-lactide) (PLLA) or from ring-opening copolymerization of l-lactide and hydroxyl-terminated PHB, as result of a previous transesterification reactions with isosorbide. Two-component blends of PHB and PIS or PLLA were also prepared as comparative systems. SEC, MALDI-TOF mass spectrometry (MALDI-TOFMS), (1)H and (13)C NMR spectroscopy, WAXD, solubility tests, and TG thermal analysis were used for characterization. The block copolymer structures of the products were evidenced by MALDI-TOFMS, (13)C NMR, and WAXD data. The block copolymers and the corresponding binary blends presented different solubility properties, as revealed by solubility tests. Although the incorporation of PIS sequences into PHB main backbone did not enhance the thermal stability of the product, it reduced its crystallinity, which could be advantageous for faster biodegradation rate. These products, composed of PHB and PIS or PLLA sequences, are an interesting alternative in biomedical applications.

Optical energy storage properties of Sr(2)MgSi(2)O(7):Eu(2+),R(3+) persistent luminescence materials

The details of the mechanism of persistent luminescence were probed by investigating the trap level structure of Sr(2)MgSi(2)O(7):Eu(2+),R(3+) materials (R: Y, La-Lu, excluding Pm and Eu) with thermoluminescence (TL) measurements and Density Functional Theory (DFT) calculations. The TL results indicated that the shallowest traps for each Sr(2)MgSi(2)O(7):Eu(2+),R(3+) material above room temperature were always ca. 0.7 eV corresponding to a strong TL maximum at ca. 90 A degrees C. This main trap energy was only slightly modified by the different co-dopants, which, in contrast, had a significant effect on the depths of the deeper traps. The combined results of the trap level energies obtained from the experimental data and DFT calculations suggest that the main trap responsible for the persistent luminescence of the Sr(2)MgSi(2)O(7):Eu(2+),R(3+) materials is created by charge compensation lattice defects, identified tentatively as oxygen vacancies, induced by the R(3+) co-dopants.

Diagnostiskt läs- och skrivprov - ett verktyg för att identifiera elever som riskerar att ej nå målen i svenska, år 3?

Vi har i detta arbete jämfört resultat i DLS-prov, moment läsförståelse, för ett antal elever i år 3 med deras resultat gällande läsförståelse vid de nationella proven. Vi ville se om dessa två prov bedömer läsförståelsen på samma sätt, för att se om DLS kan vara användbart som test för att hitta elever som behöver stöd när det gäller läsförståelse. Vårt resultat visar att det finns en överensstämmelse mellan våra elevers resultat på DLS-provet och samma elevers resultat på läsförståelsedelarna i de nationella proven för årskurs 3, 2011. Sambandet är signifikant starkare när vi jämför med resultaten på enbart Delprov B (läsning av skönlitterär text) än då vi jämför med resultaten för hela läsförståelseavsnittet respektive Delprov C (läsning av faktatext).   Resultatet för våra elever tyder på att DLS kan vara användbart som test för att hitta elever som behöver stöd när det gäller läsförståelse av skönlitterära texter. Det är mer tveksamt om DLS är användbart för att fånga upp de elever som har svårigheter med läsförståelsen då det gäller läsning av faktatext.   Det behövs dock mer tidskrävande och komplexa bedömningsformer för att vi ska kunna hjälpa eleverna att utveckla alla de förmågor och färdigheter som finns i kursplanemålen. En bra bedömning kan bara göras utifrån ett test om testet stämmer mycket väl överens med målet i kursplanen. Resultatet från en sådan test kan dessutom hjälpa läraren att utveckla sin undervisning.

Transformação organizacional via "SAP R/3": por que algumas implementações fracassam ?

Trata das dificuldades e desafios encontrados durante as implementações do SAP R/3. Resulta de entrevistas realizadas pelo autor durante 3 anos de acompanhamento de implementações em empresas no Brasil e nos Estados Unidos. Identifica razões do fracasso e faz recomendações para se evitar problemas durante a implementação do- SAP R/3 nas empresas

Vacuum effects on massive spinor fields: S-1 x R-3 topology

The aim of this work was to investigate the role played by an external field on the Casimir energy density for massive fermions under S-1 x R-3 topology. Both twisted- and untwisted-spin connections are considered and the calculation in a closed form is performed using an alternative approach based on the combination of the analytic regularization method and the Euler-Maclaurin summation formula. It is shown that no mass scale appears in the final result and, therefore, Casimir effect arises only from the boundary conditions and vacuum fluctuations induced by the coupling with the external field.

Boundary of the rauzy fractal sets in R x C generated by P(x)=x(4)-x(3)-x(2)-x-1

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

On pairs of regular foliations in R(3) and singularities of map-germs

We study germs of pairs of codimension one regular foliations in R(3) . We show that the discriminant of the pair determines the topological type of the pair. We also consider various classifications of the singularities of the discriminant.

Spinning Hopf solitons on S-3 x R

We consider a field theory with target space being the two dimensional sphere S-2 and defined on the space-time S-3 x R. The Lagrangean is the square of the pull-back of the area form on S-2. It is invariant under the conformal group SO(4, 2) and the infinite dimensional group of area preserving diffeomorphisms of S-2. We construct an infinite number of exact soliton solutions with non-trivial Hopf topological charges. The solutions spin with a frequency which is bounded above by a quantity proportional to the inverse of the radius of S-3. The construction of the solutions is made possible by an ansatz which explores the conformal symmetry and a U(1) subgroup of the area preserving diffeomorphism group.

Periodic orbits for a class of reversible quadratic vector field on R-3

For a class of reversible quadratic vector fields on R-3 we study the periodic orbits that bifurcate from a heteroclinic loop having two singular points at infinity connected by an invariant straight line in the finite part and another straight line at infinity in the local chart U-2. More specifically, we prove that for all n is an element of N, there exists epsilon(n) > 0 such that the reversible quadratic polynomial differential systemx = a(0) + a(1y) + a(3y)(2) + a(4Y)(2) + epsilon(a(2x)(2) + a(3xz)),y = b(1z) + b(3yz) + epsilon b(2xy),z = c(1y) +c(4az)(2) + epsilon c(2xz)in R-3, with a(0) < 0, b(1)c(1) < 0, a(2) < 0, b(2) < a(2), a(4) > 0, c(2) < a(2) and b(3) is not an element of (c(4), 4c(4)), for epsilon is an element of (0, epsilon(n)) has at least n periodic orbits near the heteroclinic loop. (c) 2007 Elsevier B.V. All rights reserved.

Regularization of discontinuous vector fields on R-3 via singular perturbation

Singular perturbations problems in dimension three which are approximations of discontinuous vector fields are studied in this paper. The main result states that the regularization process developed by Sotomayor and Teixeira produces a singular problem for which the discontinuous set is a center manifold. Moreover, the definition of' sliding vector field coincides with the reduced problem of the corresponding singular problem for a class of vector fields.

Contact properties of surfaces in r-3 with corank 1 singularities

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Normal Forms for Polynomial Differential Systems in R-3 Having an Invariant Quadric and a Darboux Invariant

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Intercambio de información entre sistemas SAP R/3-Knapp para optimizar el proceso de expedición de pedidos

[ES] El objetivo de este Trabajo es el de parametrizar, implementar las estructuras de datos y programar las aplicaciones necesarias que posibilitan el intercambio de información entre dos entornos software, SAP R/3 y Knapp, líderes en sus campos de actuación. El resultado de aplicar tales cambios permitirá a la organización no sólo centralizar la información en el ERP, sino que mejorará sus procesos de negocio y agilizará la toma de decisiones por parte de los responsables. Se realiza un estudio de la situación actual y, tras un análisis detallado, se propone una solución que permita alcanzar los objetivos propuestos. Una vez diseñada, presentada y aprobada la propuesta, se procede a la parametrización de SAP R/3, a la definición de los segmentos y tipos de IDOC y a la codificación de funciones y programas que permitan tratar la información enviada por Knapp. Finalizadas estas tareas, se elaboran juegos de datos de los procesos comerciales y se ejecutan en un entorno de test, en colaboración con los usuarios claves, para comprobar la bondad de la solución implementada. Se analizan los resultados y se corrigen posibles deficiencias. Finalmente se transporta al sistema productivo todos los cambios realizados y se verifica la correcta ejecución de los procesos de negocio de la organización.