4D/3D reduction of dualities: mirrors on the circle

We engineer a brane picture for the reduction of Seiberg dualities from 4D to 3D, valid also in the presence of orientifold planes. We obtain effective 3D dualities on the circle by T-duality, geometrizing the non-perturbative superpotential which is an affine Toda potential. When reducing to pure 3D, we define a double-scaling limit which creates a sector of interacting singlets, giving a unified mechanism for the brane reduction of dualities.

Noninvasive 4D pressure difference mapping derived from 4D flow MRI in patients with repaired aortic coarctation: comparison with young healthy volunteers

To assess spatial and temporal pressure characteristics in patients with repaired aortic coarctation compared to young healthy volunteers using time-resolved velocity-encoded three-dimensional phase-contrast magnetic resonance imaging (4D flow MRI) and derived 4D pressure difference maps. After in vitro validation against invasive catheterization as gold standard, 4D flow MRI of the thoracic aorta was performed at 1.5T in 13 consecutive patients after aortic coarctation repair without recoarctation and 13 healthy volunteers. Using in-house developed processing software, 4D pressure difference maps were computed based on the Navier-Stokes equation. Pressure difference amplitudes, maximum slope of pressure amplitudes and spatial pressure range at mid systole were retrospectively measured by three readers, and twice by one reader to assess inter- and intraobserver agreement. In vitro, pressure differences derived from 4D flow MRI showed excellent agreement to invasive catheter measurements. In vivo, pressure difference amplitudes, maximum slope of pressure difference amplitudes and spatial pressure range at mid systole were significantly increased in patients compared to volunteers in the aortic arch, the proximal descending and the distal descending thoracic aorta (p < 0.05). Greatest differences occurred in the proximal descending aorta with values of the three parameters for patients versus volunteers being 19.7 ± 7.5 versus 10.0 ± 2.0 (p < 0.001), 10.9 ± 10.4 versus 1.9 ± 0.4 (p = 0.002), and 8.7 ± 6.3 versus 1.6 ± 0.9 (p < 0.001). Inter- and intraobserver agreements were excellent (p < 0.001). Noninvasive 4D pressure difference mapping derived from 4D flow MRI enables detection of altered intraluminal aortic pressures and showed significant spatial and temporal changes in patients with repaired aortic coarctation.

Improving 4D plan quality for PBS-based liver tumour treatments by combining online image guided beam gating with rescanning.

Pencil beam scanned (PBS) proton therapy has many advantages over conventional radiotherapy, but its effectiveness for treating mobile tumours remains questionable. Gating dose delivery to the breathing pattern is a well-developed method in conventional radiotherapy for mitigating tumour-motion, but its clinical efficiency for PBS proton therapy is not yet well documented. In this study, the dosimetric benefits and the treatment efficiency of beam gating for PBS proton therapy has been comprehensively evaluated. A series of dedicated 4D dose calculations (4DDC) have been performed on 9 different 4DCT(MRI) liver data sets, which give realistic 4DCT extracting motion information from 4DMRI. The value of 4DCT(MRI) is its capability of providing not only patient geometries and deformable breathing characteristics, but also includes variations in the breathing patterns between breathing cycles. In order to monitor target motion and derive a gating signal, we simulate time-resolved beams' eye view (BEV) x-ray images as an online motion surrogate. 4DDCs have been performed using three amplitude-based gating window sizes (10/5/3 mm) with motion surrogates derived from either pre-implanted fiducial markers or the diaphragm. In addition, gating has also been simulated in combination with up to 19 times rescanning using either volumetric or layered approaches. The quality of the resulting 4DDC plans has been quantified in terms of the plan homogeneity index (HI), total treatment time and duty cycle. Results show that neither beam gating nor rescanning alone can fully retrieve the plan homogeneity of the static reference plan. Especially for variable breathing patterns, reductions of the effective duty cycle to as low as 10% have been observed with the smallest gating rescanning window (3 mm), implying that gating on its own for such cases would result in much longer treatment times. In addition, when rescanning is applied on its own, large differences between volumetric and layered rescanning have been observed as a function of increasing number of re-scans. However, once gating and rescanning is combined, HI to within 2% of the static plan could be achieved in the clinical target volume, with only moderately prolonged treatment times, irrespective of the rescanning strategy used. Moreover, these results are independent of the motion surrogate used. In conclusion, our results suggest image guided beam gating, combined with rescanning, is a feasible, effective and efficient motion mitigation approach for PBS-based liver tumour treatments.

Temporally Coherent Disparity Maps Using CRFs with Fast 4D Filtering

State of the art methods for disparity estimation achieve good results for single stereo frames, but temporal coherence in stereo videos is often neglected. In this paper we present a method to compute temporally coherent disparity maps. We define an energy over whole stereo sequences and optimize their Conditional Random Field (CRF) distributions using mean-field approximation. We introduce novel terms for smoothness and consistency between the left and right views, and perform CRF optimization by fast, iterative spatio-temporal filtering with linear complexity in the total number of pixels. Our results rank among the state of the art while having significantly less flickering artifacts in stereo sequences.

La problemática del chagas en 4d : Representaciones de docentes de nivel inicial y primario de La Plata

Se presenta el análisis de las representaciones sociales de docentes de nivel primario e inicial de la región de La Plata que asistieron a dos cursos de formación continua en el contexto de la realización de "La Semana del Chagas en el Museo de La Plata" en 2011. La propuesta implementada, destinada a difundir y visibilizar al tema como problemática compleja, incluyó un abordaje integral e interdisciplinario a partir de múltiples miradas, involucrando diferentes recursos y actores, planteando la problemática desde cuatro grandes dimensiones (biomédica, epidemiológica, sociocultural-económica y política). Las representaciones, identificadas a partir de textos producidos en respuesta a la pregunta ¿De qué hablamos cuando hablamos de Chagas?, reflejan fuertemente el discurso biomédico hegemónico, pero dando también lugar a la posibilidad de ver al tema como un problema más complejo, en el que lo social y lo político -y dentro de éste, lo educativo y el propio rol como docentes- están presentes

La problemática del chagas en 4d : Representaciones de docentes de nivel inicial y primario de La Plata

Se presenta el análisis de las representaciones sociales de docentes de nivel primario e inicial de la región de La Plata que asistieron a dos cursos de formación continua en el contexto de la realización de "La Semana del Chagas en el Museo de La Plata" en 2011. La propuesta implementada, destinada a difundir y visibilizar al tema como problemática compleja, incluyó un abordaje integral e interdisciplinario a partir de múltiples miradas, involucrando diferentes recursos y actores, planteando la problemática desde cuatro grandes dimensiones (biomédica, epidemiológica, sociocultural-económica y política). Las representaciones, identificadas a partir de textos producidos en respuesta a la pregunta ¿De qué hablamos cuando hablamos de Chagas?, reflejan fuertemente el discurso biomédico hegemónico, pero dando también lugar a la posibilidad de ver al tema como un problema más complejo, en el que lo social y lo político -y dentro de éste, lo educativo y el propio rol como docentes- están presentes

La problemática del chagas en 4d : Representaciones de docentes de nivel inicial y primario de La Plata

Se presenta el análisis de las representaciones sociales de docentes de nivel primario e inicial de la región de La Plata que asistieron a dos cursos de formación continua en el contexto de la realización de "La Semana del Chagas en el Museo de La Plata" en 2011. La propuesta implementada, destinada a difundir y visibilizar al tema como problemática compleja, incluyó un abordaje integral e interdisciplinario a partir de múltiples miradas, involucrando diferentes recursos y actores, planteando la problemática desde cuatro grandes dimensiones (biomédica, epidemiológica, sociocultural-económica y política). Las representaciones, identificadas a partir de textos producidos en respuesta a la pregunta ¿De qué hablamos cuando hablamos de Chagas?, reflejan fuertemente el discurso biomédico hegemónico, pero dando también lugar a la posibilidad de ver al tema como un problema más complejo, en el que lo social y lo político -y dentro de éste, lo educativo y el propio rol como docentes- están presentes