3D noise power spectrum applied on clinical mdct scanners: effects of reconstruction algorithms and reconstruction filters

The noise power spectrum (NPS) is the reference metric for understanding the noise content in computed tomography (CT) images. To evaluate the noise properties of clinical multidetector (MDCT) scanners, local 2D and 3D NPSs were computed for different acquisition reconstruction parameters.A 64- and a 128-MDCT scanners were employed. Measurements were performed on a water phantom in axial and helical acquisition modes. CT dose index was identical for both installations. Influence of parameters such as the pitch, the reconstruction filter (soft, standard and bone) and the reconstruction algorithm (filtered-back projection (FBP), adaptive statistical iterative reconstruction (ASIR)) were investigated. Images were also reconstructed in the coronal plane using a reformat process. Then 2D and 3D NPS methods were computed.In axial acquisition mode, the 2D axial NPS showed an important magnitude variation as a function of the z-direction when measured at the phantom center. In helical mode, a directional dependency with lobular shape was observed while the magnitude of the NPS was kept constant. Important effects of the reconstruction filter, pitch and reconstruction algorithm were observed on 3D NPS results for both MDCTs. With ASIR, a reduction of the NPS magnitude and a shift of the NPS peak to the low frequency range were visible. 2D coronal NPS obtained from the reformat images was impacted by the interpolation when compared to 2D coronal NPS obtained from 3D measurements.The noise properties of volume measured in last generation MDCTs was studied using local 3D NPS metric. However, impact of the non-stationarity noise effect may need further investigations.

Design, Fabrication, and Operation of the Pavement Crack Monitor Gauge, HR-1054, 1990

A mechanical gauge was developed to monitor the movement of crack or joint openings in portland cement concrete structures, in general, and portland cement concrete pavements in particular. Designed to be inexpensive and simple to operate, this gauge is capable of recording maximum, minimum, and instantaneous crack or joint openings. Specific recommendations were made for recording minimum and maximum pavement temperature over the monitoring period. The report was written as a set of guidelines for design, fabrication, installation, and operation of the gauge as well as the temperature measuring device.

Enquête sur la mode féminine : [plaquette de prestige] / High-Life Taylor ; [texte signé J.R.] ; [ill. de Bernard B. de Monvel, Maurice Leloir, L. Sabattier,...]

Mécénat texte imprimé : Cet ouvrage a été numérisé grâce à Myriam Lenourry

From caging to rouse dynamics in polymer melts with intramolecular barriers: a critical test of the mode coupling theory

By means of computer simulations and solution of the equations of the mode coupling theory (MCT),we investigate the role of the intramolecular barriers on several dynamic aspects of nonentangled polymers. The investigated dynamic range extends from the caging regime characteristic of glass-formers to the relaxation of the chain Rouse modes. We review our recent work on this question,provide new results, and critically discuss the limitations of the theory. Solutions of the MCT for the structural relaxation reproduce qualitative trends of simulations for weak and moderate barriers. However, a progressive discrepancy is revealed as the limit of stiff chains is approached. This dis-agreement does not seem related with dynamic heterogeneities, which indeed are not enhanced by increasing barrier strength. It is not connected either with the breakdown of the convolution approximation for three-point static correlations, which retains its validity for stiff chains. These findings suggest the need of an improvement of the MCT equations for polymer melts. Concerning the relaxation of the chain degrees of freedom, MCT provides a microscopic basis for time scales from chain reorientation down to the caging regime. It rationalizes, from first principles, the observed deviations from the Rouse model on increasing the barrier strength. These include anomalous scaling of relaxation times, long-time plateaux, and nonmonotonous wavelength dependence of the mode correlators.

Conceptes, notes i comentaris econòmics sobre la incertesa a mode de vocabulari bàsic i quadre síntètic

Gairebé han passat 20 anys d’ençà que vaig començar a reflexionar sobre la incertesa dela mà del Dr. Dídac Ramírez. Vaig presentar una tesi dirigida per ell l’any 2003, he fetarticles, he presentat comunicacions en seminaris i col·loquis. El tema de la incertesa ésmolt ampli; es relaciona amb el coneixement, l'aleatorietat, el caos, l'ètica, la psicologia,etc. En aquests 20 anys, a poc a poc, he anat lligant alguns caps i, en aquests moments,penso que pot tenir interès presentar al seminari IAFI del Departament de Matemàtiquesde la Facultat d’Econòmiques de la UB un esquema amb aquestes idees lligades enforma de vocabulari.Molts dels termes del vocabulari els proposo jo, per la qual cosa no m’he pogut limitar adonar una definició precisa i he necessitat posar explicacions i exemples per tal dejustificar el seu interès.

Fonder un nouveau mode de redistribution des aides sociales sur une philosophie de la personne?

Cet article présente un nouveau modèle de redistribution des aides sociales en France, le mécanisme de "l'allocation personnelle", fondé sur une nouvelle conception des mutuelles auxquelles est assigné un rôle de redistribution. L'enjeu de ce papier est de mettre en avant les fondements philosophiques qui sous-tendent cette nouvelle conception de la redistribution, en particulier la philosophie personnaliste.

Itinéraire clinique en traumatologie, une mode ou un besoin [Clinical pathway in traumatology, a fashion or need?].

A clinical route is defined as a "set of methods and instruments to members of a multidisciplinary and Interprofessional team to agree on the tasks for a specific patient population. This is a program of care to ensure the provision of quality care and efficient realization". The University Hospital is not immune to this phenomenon. In the Department of the musculoskeletal system, a first project of this kind concerns the fracture of the proximal femur in the elderly.

Entre résistance et contestation. La genèse du squat comme mode d'action

Cette contribution vise plusieurs objectifs théoriques : questionner les implicites du concept de répertoire d'action pour proposer une typification des modes d'action, indiquer des pistes pour une analyse conjointe des répertoires instrumentaux et discursifs mis en oeuvre par les organisations, reconsidérer les ruptures historiques mises au jour par Charles Tilly, et enfin réfléchir aux conditions organisationnelles et contextuelles favorisant l'usage de formes d'actions directes. Elle se fonde empiriquement sur l'étude de la genèse d'un mode d'action spécifique, le squat, entre 1880 et 1914, au moyen d'un travail d'archives et d'un travail d'étymologie. On montre notamment que le passage de la « résistance » à la « contestation », dans laquelle prédomine le « revendiqué », suppose une forme particulière de rapport au politique qui, au début de ce siècle, constituait en soi un enjeu de luttes important entre différents groupes.

Transposition of great arteries and single coronary artery: a new surgical technique for the arterial switch operation.

A single coronary artery can complicate the surgical technique of arterial switch operations, impairing early and late outcomes. We propose a new surgical approach, successfully applied in a 2.1 kg neonate, aimed at reducing the risk of early and late compression and/or distortion of the newly constructed coronary artery system.

Long diagnostic delay in Crohn's disease is associated with complicated disease course and increased operation rate

Background: We have recently shown that the median diagnostic delay to establish Crohn's disease (CD) diagnosis in the Swiss IBD Cohort (SIBDC) was 9 months. Seventy five percent of all CD patients were diagnosed within 24 months. The clinical impact of a long diagnostic delay on the natural history of CD is unknown. Aim: To compare the frequency and type of CD-related complications in the patient groups with long diagnostic delay (>24 months) vs. the ones diagnosed within 24 months. Methods: Retrospective analysis of data from the SIBDCS, comprising a large sample of CD patients followed in hospitals and private practices across Switzerland. Results: Two hundred CD patients (121 female, mean age 44.9 ± 15.0 years, 38% smokers, 71% ever treated with immunomodulators and 35% with anti-TNF) with long diagnostic delay were compared to 697 CD patients (358 female, mean age 39.1 ± 14.9 years, 33% smokers, 74% ever treated with immunomodulators and 33% with anti-TNF) diagnosed within 24 months. No differences in the outcomes were observed between the two patient groups within year one after CD diagnosis. Among those diagnosed 2-5 years ago, CD patients with long diagnostic delay (n = 45) presented more frequently with internal fistulas (11.1% vs. 3.1%, p = 0.03) and bowel stenoses (28.9% vs. 15.7%, p = 0.05), and they more frequently underwent CD-related operations (15.6% vs. 5.0%, p = 0.02) compared to the patients diagnosed within 24 months (n = 159). Among those diagnosed 6-10 years ago, CD patients with long diagnostic delay (n = 48) presented more frequently with extraintestinal manifestations (60.4% vs. 34.6%, p = 0.001) than those diagnosed within 24 months (n = 182). For the patients diagnosed 11-15 years ago, no differences in outcomes were found between the long diagnostic delay group (n = 106) and the one diagnosed within 24 months (n = 32). Among those diagnosed >= 16 years ago, the group with long diagnostic delay (n = 71) more frequently underwent CD-related operations (63.4% vs. 46.5%, p = 0.01) compared to the group diagnosed with CD within 24 months (n = 241). Conclusions: A long diagnostic delay in CD patients is associated with a more complicated disease course and higher number of CD-related operations in the years following the diagnosis. Our results indicate that efforts should be undertaken to shorten the diagnostic delay in CD patients in order to reduce the risk for progression towards a complicated disease phenotype.

Structural Insight into the Mode of Action of a Direct Inhibitor of Coregulator Binding to the Thyroid Hormone Receptor.

The development of nuclear hormone receptor antagonists that directly inhibit the association of the receptor with its essential coactivators would allow useful manipulation of nuclear hormone receptor signaling. We previously identified 3-(dibutylamino)-1-(4-hexylphenyl)-propan-1-one (DHPPA), an aromatic β-amino ketone that inhibits coactivator recruitment to thyroid hormone receptor β (TRβ), in a high-throughput screen. Initial evidence suggested that the aromatic β-enone 1-(4-hexylphenyl)-prop-2-en-1-one (HPPE), which alkylates a specific cysteine residue on the TRβ surface, is liberated from DHPPA. Nevertheless, aspects of the mechanism and specificity of action of DHPPA remained unclear. Here, we report an x-ray structure of TRβ with the inhibitor HPPE at 2.3-Å resolution. Unreacted HPPE is located at the interface that normally mediates binding between TRβ and its coactivator. Several lines of evidence, including experiments with TRβ mutants and mass spectroscopic analysis, showed that HPPE specifically alkylates cysteine residue 298 of TRβ, which is located near the activation function-2 pocket. We propose that this covalent adduct formation proceeds through a two-step mechanism: 1) β-elimination to form HPPE; and 2) a covalent bond slowly forms between HPPE and TRβ. DHPPA represents a novel class of potent TRβ antagonist, and its crystal structure suggests new ways to design antagonists that target the assembly of nuclear hormone receptor gene-regulatory complexes and block transcription.