An Efficient Solution to the Factorized Geometrical Autofocus Problem

This paper describes a new search strategy within the scope of factorized geometrical autofocus (FGA) and synthetic-aperture-radar processing. The FGA algorithm is a fast factorized back-projection formulation with six adjustable geometry parameters. By tuning the flight track step by step and maximizing focus quality by means of an object function, a sharp image is formed. We propose an efficient two-stage approach for the geometrical variation. The first stage is a low-order (few parameters) parallel search procedure involving small image areas. The second stage then combines the local hypotheses into one global autofocus solution, without the use of images. This method has been applied successfully on ultrawideband CARABAS II data. Errors due to a constant acceleration are superposed on the measured track prior to processing, giving a 6-D autofocus problem. Image results, including resolution, peak-to-sidelobe ratio and magnitude values for point-like targets, finally confirm the validity of the strategy. The results also verify the prediction that there are several satisfying autofocus solutions for the same radar data

Factorized Geometrical Autofocus for Synthetic Aperture Radar Processing

This paper describes a factorized geometrical autofocus (FGA) algorithm, specifically suitable for ultrawideband synthetic aperture radar. The strategy is integrated in a fast factorized back-projection chain and relies on varying track parameters step by step to obtain a sharp image; focus measures are provided by an object function (intensity correlation). The FGA algorithm has been successfully applied on synthetic and real (Coherent All RAdio BAnd System II) data sets, i.e., with false track parameters introduced prior to processing, to set up constrained problems involving one geometrical quantity. Resolution (3 dB in azimuth and slant range) and peak-to-sidelobe ratio measurements in FGA images are comparable with reference results (within a few percent and tenths of a decibel), demonstrating the capacity to compensate for residual space variant range cell migration. The FGA algorithm is finally also benchmarked (visually) against the phase gradient algorithm to emphasize the advantage of a geometrical autofocus approach

Способы модифицирования сварного соединения нанопорошками

В статье рассмотрены способы модифицирования сварного соединения наноструктурированными порошками

EXPOSICIÓN A Leptospira sp. EN ESTUDIANTES DE MEDICINA VETERINARIA AL INICIO Y TÉRMINO DE LA CARRERA

Leptospirosis is globally known as the most prevalent zoonotic disease, caused by different Leptospira sp. serovars. In urban areas, exposure is mainly related to certain occupational health groups, such as veterinary students. The objective of the research was to determine the rate of serorreactors to leptospira in veterinary students on two stages of their studies, at the beginning (sophomore students) and at the end (senior students). Pool serum samples were analized by the microagglutination test (MAT) for serovars canicola, icterohemorragiae, grippotyphosa, georgia, pomona and hardjo. Positive result were 18.4% (7/38) for sophomore students and 8.8% (7/80) for seniors. The positive serovars were georgia for the sophomore students, and georgia, icterohemorragiae and canicola for the seniors. The risk of infection was 2.4 (0.76 – 7.28) (p=0.137) comparing sophomore versus seniors. Exposure to Leptospira infection was demonstrated in veterinary students showing the need for more research on the main risk factors related to its presentation.La leptospirosis es la enfermedad zoonótica de mayor prevalencia a nivel mundial, la cual es causada por diferentes serovares de Leptospira sp. En el medio urbano, la población expuesta corresponde a grupos ocupacionales, entre los que se encuentran los estudiantes de ciencias veterinarias. Para determinar la frecuencia de serorreactores en estudiantes de medicina veterinaria en dos etapas de la carrera (ingresantes y prácticas finales), se tomaron muestras de sangre que fueron analizadas mediante la prueba de microaglutinación de grupos para los serovares canicola, icterohemorragiae, grippotyphosa, georgia, pomona y hardjo. El 18.4% (7/38) de ingresantes y 8.8% (7/ 80) de alumnos de prácticas finales resultaron seropositivos. Los serovares reactivos fueron georgia en ingresantes, y georgia, icterohemorragiae y canicola en alumnos de prácticas finales. El riesgo de infección fue de 2.4 (0.76 – 7.28) (p=0.137) cuando se comparó ingresantes versus prácticas finales. Se demostró la presencia de exposición a infecciones por leptospira en alumnos de veterinaria, lo que hace necesario investigar los potenciales factores de riesgo asociados a su presentación

Gated communities: Definitions, causes and consequences

Gated communities became an 'object of study' in the 1990s as social scientists observed their growth in several cities; they are now a feature of the urban landscape in most cities around the world. The expansion of gated communities has led to prolific research, examining different aspects of this type of residential development and providing evidence from case studies worldwide. This paper reviews how gated communities are conceptualised according to the literature and identifies the main factors influencing their development. It also considers spatial, economic, political and social consequences of the development of gated communities. These elements should be taken into account by planners and policymakers to minimise their negative impacts and maximise the positive consequences of a residential option that is likely to be part of the urban landscape for a long time

A fatal case of AIDS-defining meningoencephalitis by C. Neoformans, sensitive to antifungal therapy

Cryptococcus neoformans is the most common cause of life threatening meningoencephalitis in HIV-infected patients. Diagnosis is based on tests for cryptoccocal antigen in serum and cerebrospinal fluid, and on culture of the organism. We present a case of AIDS-related cryptococcal meningoencephalitis unresponsive to antifungal combination therapy, despite of evidence of fungal susceptibility in vitro. Significant decreases in cryptococcal antigen titers in serum and cerebrospinal fluid did not correlate with progress in disease and fatal outcome

Mechanistic insight into RET kinase inhibitors targeting the DFG-out conformation in RET-rearranged cancer

Oncogenic fusion events have been identified in a broad range of tumors. Among them, RET rearrangements represent distinct and potentially druggable targets that are recurrently found in lung adenocarcinomas. Here, we provide further evidence that current anti-RET drugs may not be potent enough to induce durable responses in such tumors. We report that potent inhibitors such as AD80 or ponatinib that stably bind in the DFG-out conformation of RET may overcome these limitations and selectively kill RET-rearranged tumors. Using chemical genomics in conjunction with phosphoproteomic analyses in RET-rearranged cells we identify the CCDC6-RETI788N mutation and drug-induced MAPK pathway reactivation as possible mechanisms, by which tumors may escape the activity of RET inhibitors. Our data provide mechanistic insight into the druggability of RET kinase fusions that may be of help for the development of effective therapies targeting such tumors

Multislice CT angiography in the selection of patients with ruptured intracranial aneurysms suitable for clipping or coiling

Introduction We sought to establish whether CT angiography (CTA) can be applied to the planning and performance of clipping or coiling in ruptured intracranial aneurysms without recourse to intraarterial digital subtraction angiography (IA-DSA). Methods Over the period April 2003 to January 2006 in all patients presenting with a subarachnoid haemorrhage CTA was performed primarily. If CTA demonstrated an aneurysm, coiling or clipping was undertaken. IA-DSA was limited to patients with negative or inconclusive CTA findings. We compared CTA images with findings at surgery or coiling in patients with positive CTA findings and in patients with negative and inconclusive findings in whom IA-DSA had been performed. Results In this study, 224 consecutive patients (mean age 52.7 years, 135 women) were included. In 133 patients (59%) CTA demonstrated an aneurysm, and CTA was followed directly by neurosurgical (n=55) or endovascular treatment (n=78). In 31 patients (14%) CTA findings were categorized as inconclusive, and in 60 (27%) CTA findings were negative. One patient received surgical treatment on the basis of false-positive CTA findings. In 17 patients in whom CTA findings were inconclusive, IA-DSA provided further diagnostic information required for correct patient selection for any therapy. Five ruptured aneurysms in patients with a nonperimesencephalic SAH were negative on CTA, and four of these were also false-negative on IA-DSA. On a patient basis the positive predictive value, negative predictive value, sensitivity, specificity and accuracy of CTA for symptomatic aneurysms were 99%, 90%, 96%, 98% and 96%, respectively. Conclusion CTA should be used as the first diagnostic modality in the selection of patients for surgical or endovascular treatment of ruptured intracranial aneurysms. If CTA renders inconclusive results, IA-DSA should be performed. With negative CTA results the complementary value of IA-DSA is marginal. IA-DSA is not needed in patients with negative CTA and classic perimesencephalic SAH. Repeat IA-DSA or CTA should still be performed in patients with a nonperimesencephalic SAH