Dynamic estimation of three-dimensional cerebrovascular deformation from rotational angiography

Purpose: The objective of this study is to investigate the feasibility of detecting and quantifying 3D cerebrovascular wall motion from a single 3D rotational x-ray angiography (3DRA) acquisition within a clinically acceptable time and computing from the estimated motion field for the further biomechanical modeling of the cerebrovascular wall. Methods: The whole motion cycle of the cerebral vasculature is modeled using a 4D B-spline transformation, which is estimated from a 4D to 2D + t image registration framework. The registration is performed by optimizing a single similarity metric between the entire 2D + t measured projection sequence and the corresponding forward projections of the deformed volume at their exact time instants. The joint use of two acceleration strategies, together with their implementation on graphics processing units, is also proposed so as to reach computation times close to clinical requirements. For further characterizing vessel wall properties, an approximation of the wall thickness changes is obtained through a strain calculation. Results: Evaluation on in silico and in vitro pulsating phantom aneurysms demonstrated an accurate estimation of wall motion curves. In general, the error was below 10% of the maximum pulsation, even in the situation when substantial inhomogeneous intensity pattern was present. Experiments on in vivo data provided realistic aneurysm and vessel wall motion estimates, whereas in regions where motion was neither visible nor anatomically possible, no motion was detected. The use of the acceleration strategies enabled completing the estimation process for one entire cycle in 5-10 min without degrading the overall performance. The strain map extracted from our motion estimation provided a realistic deformation measure of the vessel wall. Conclusions: The authors' technique has demonstrated that it can provide accurate and robust 4D estimates of cerebrovascular wall motion within a clinically acceptable time, although it has to be applied to a larger patient population prior to possible wide application to routine endovascular procedures. In particular, for the first time, this feasibility study has shown that in vivo cerebrovascular motion can be obtained intraprocedurally from a 3DRA acquisition. Results have also shown the potential of performing strain analysis using this imaging modality, thus making possible for the future modeling of biomechanical properties of the vascular wall.

Outage thresholds of LDPC codes over nonergodic block-fading channels

This paper derives approximations allowing the estimation of outage probability for standard irregular LDPC codes and full-diversity Root-LDPC codes used over nonergodic block-fading channels. Two separate approaches are discussed: a numerical approximation, obtained by curve fitting, for both code ensembles, and an analytical approximation for Root-LDPC codes, obtained under the assumption that the slope of the iterative threshold curve of a given code ensemble matches the slope of the outage capacity curve in the high-SNR regime.

On iterative performance of LDPC and Root-LDPC codes over block-fading channels

This paper presents our investigation on iterativedecoding performances of some sparse-graph codes on block-fading Rayleigh channels. The considered code ensembles are standard LDPC codes and Root-LDPC codes, first proposed in and shown to be able to attain the full transmission diversity. We study the iterative threshold performance of those codes as a function of fading gains of the transmission channel and propose a numerical approximation of the iterative threshold versus fading gains, both both LDPC and Root-LDPC codes.Also, we show analytically that, in the case of 2 fading blocks,the iterative threshold root of Root-LDPC codes is proportional to (α1 α2)1, where α1 and α2 are corresponding fading gains.From this result, the full diversity property of Root-LDPC codes immediately follows.

Multiuser detection with an unknown number of active users: receiver design

In multiuser detection, the set of users active at any time may be unknown to the receiver. In these conditions, optimum reception consists of detecting simultaneously the set of activeusers and their data, problem that can be solved exactly by applying random-set theory (RST) and Bayesian recursions (BR). However, implementation of optimum receivers may be limited by their complexity, which grows exponentially with the number of potential users. In this paper we examine three strategies leading to reduced-complexity receivers.In particular, we show how a simple approximation of BRs enables the use of Sphere Detection (SD) algorithm, whichexhibits satisfactory performance with limited complexity.

Swain: Stata module to correct the SEM chi-square overidentification test in small sample sizes or complex models. Statistical Software Components S457617, Boston College Department of Economics.

Swain corrects the chi-square overidentification test (i.e., likelihood ratio test of fit) for structural equation models whethr with or without latent variables. The chi-square statistic is asymptotically correct; however, it does not behave as expected in small samples and/or when the model is complex (cf. Herzog, Boomsma, & Reinecke, 2007). Thus, particularly in situations where the ratio of sample size (n) to the number of parameters estimated (p) is relatively small (i.e., the p to n ratio is large), the chi-square test will tend to overreject correctly specified models. To obtain a closer approximation to the distribution of the chi-square statistic, Swain (1975) developed a correction; this scaling factor, which converges to 1 asymptotically, is multiplied with the chi-square statistic. The correction better approximates the chi-square distribution resulting in more appropriate Type 1 reject error rates (see Herzog & Boomsma, 2009; Herzog, et al., 2007).

On the goodness of fit of Kirk's formula for spread option prices

In this paper we investigate the goodness of fit of the Kirk's approximation formula for spread option prices in the correlated lognormal framework. Towards this end, we use the Malliavin calculus techniques to find an expression for the short-time implied volatility skew of options with random strikes. In particular, we obtain that this skew is very pronounced in the case of spread options with extremely high correlations, which cannot be reproduced by a constant volatility approximation as in the Kirk's formula. This fact agrees with the empirical evidence. Numerical examples are given.

U-Pb zircon dating of granitoids from the Dora-Maira massif (western Italian Alps)

Among the large number of granitic intrusions within the Dora-Maira massif, several main types can be distinguished. In this study we report field, petrographic and geochemical investigations as well as zircon typology and conventional U-Pb zircon dating of plutons representing these types. The main results are as follows: the Punta Muret augengneiss is a polymetamorphosed peraluminous granite of anatectic origin. It is 457 +/- 2 Ma old and represents one of the numerous Caledonian orthogneisses of the Alpine basement. All other dated granites are of Late Variscan age. The Cavour leucogranite is an evolved granite of probably calc-alkaline affiliation, dated at 304 +/- 2 Ma. The dioritic and granodioritic facies of the Malanaggio diorite (auct.) are typical calc-alkaline rocks, whose respective age of 290 +/- 2 and 288 +/- 2 Ma overlap within errors. The Sangone and Freidour granite types have very similar alkali-calcic characteristics; their ages are poorly constrained between 267-279 and 268-283 Ma, respectively. The new data for the Dora-Maira granites are in keeping with models of the overall evolution of the Late- to Post-Variscan magmatism in the Alpine area in terms of age distribution and progressive geochemical evolution towards alkaline melts. In a first approximation, granitic rocks across the Variscan belt seem to be increasingly younger towards the internal (southern) parts of the orogen. A Carboniferous, distensive Basin and Range situation is thought to be responsible for the magmatic activity. This tectonic context is comparable to the back-are opening of an active continental margin. The observed southward migration of the magmatism could be linked to the roll-back of the subducting Paleotethyan oceanic plate along the Variscan cordillera.

Scores composites CHC pour la WAIS-IV : normes francophones

Les résultats des recherches contemporaines, montrant notamment l'importance du raisonnement fluide, de la mémoire de travail (IMT) et de la vitesse de traitement (IVT) dans le fonctionnement cognitif, ont conduit les concepteurs de la WAIS-IV à introduire de nouvelles épreuves pour renforcer l'évaluation de ces dimensions cognitives. L'interprétation des scores de la WAIS-IV repose maintenant sur quatre indices factoriels (ICV, IRP, IMT et IVT), ainsi que sur le QIT. Les concepteurs de la WAIS-IV indiquent que l'un des objectifs de la révision consistait à actualiser les fondements théoriques de cette échelle. Pourtant, la structure globale de la WAIS-IV ne correspond que partiellement à celle proposée dans le modèle qui fait consensus aujourd'hui, le modèle de Cattell-Horn-Carroll (CHC). Par exemple, la WAIS-IV ne propose pas d'indice de raisonnement fluide, bien que les constructeurs soulignent l'importance de cette dimension dans le fonctionnement cognitif. Dans cet article, nous proposons, pour la WAIS-IV, les normes francophones de cinq scores composites CHC, à savoir le raisonnement fluide (Gf), compréhension-connaissances (Gc), le traitement visuel (Gv), la mémoire à court terme (Gsm), et l'IVT (Gs). Ces normes ont été établies en utilisant une procédure d'approximation statistique. À l'instar des scores CHC que nous avons proposés pour le WISCIV, ces normes pour la WAIS-IV permettent aux cliniciens de basculer vers une grille d'interprétation basée sur le modèle dominant et d'utiliser les cinq scores composites CHC en complément des quatre indices standard dans le cadre d'analyses normatives et ipsatives.

Postoperative delirium. Part 2: detection, prevention and treatment.

To target pharmacological prevention, instruments giving an approximation of an individual patient's risk of developing postoperative delirium are available. In view of the variable clinical presentation, identifying patients in whom prophylaxis has failed (that is, who develop delirium) remains a challenge. Several bedside instruments are available for the routine ward and ICU setting. Several have been shown to have a high specificity and sensitivity when compared with the standard definitions according to DSM-IV-TR and ICD-10. The Confusion Assessment Method (CAM) and a version specifically developed for the intensive care setting (CAM-ICU) have emerged as a standard. However, alternatives allowing grading of the severity of delirium are also available. In many units, the approach to delirium follows a three-step strategy. Initially, non-pharmacological multicomponent strategies are used for primary prevention. As a second step, pharmacological prophylaxis may be added. Perioperative administration of haloperidol has been shown to reduce the severity, but not the incidence, of delirium. Perioperative administration of atypical antipsychotics has been shown to reduce the incidence of delirium in specific groups of patients. In patients with delirium, both symptomatic and causal treatment of delirium need to be considered. So far symptomatic treatment of delirium is primarily based on antipsychotics. Currently, cholinesterase inhibitors cannot be recommended and the data on dexmedetomidine are inconclusive. With the exception of alcohol-withdrawal delirium, there is no role for benzodiazepines in the treatment of delirium. It is unclear whether treating delirium prevents long-term sequelae.

Problematizing the multidisciplinary residency in oncology: a practical teaching protocol from the perspective of nurse residents

Objective: To investigate practical teaching of nurse residents in a multidisciplinary residency in oncology. Method: A qualitative descriptive study grounded in the problematization methodology and its steps, represented by the Maguerez Arch. Data were analyzed using content analysis. Results: Potentiating and limiting elements of the residency guided the design of a practical teaching protocol from the perspective of residents, structured in three stages: Welcoming and ambience; Nursing care for problem situations; and, Evaluation process. Conclusion: Systematization of practical teaching promoted the autonomy of individuals and the approximation of teaching to reality, making residency less strenuous, stressful and distressing.



Nursing performance in the policy transfer of directly observed treatment of tuberculosis

Objective Analyzing the policy transfer of directly observed treatment of tuberculosis from the perspective of nursing. Method This is a descriptive study with qualitative approach, which had 10 nurses of the Family Health Strategy in São Paulo as subjects. The interviews were carried out between May and June 2013, and were adopted the technique of thematic content analysis and the referential of policy transfer. Results On the signification of this treatment, are related the senses of disciplinary monitoring, the bond and approximation to the context of patients’ lives. Operationally, nurses, community health agents and nursing technicians stand out as agents of implementation of this policy, developing multiple actions of user embracement. The nurse is evidenced as an educator in health, leader in the family health team, and capable of creating emotional bond with users. Conclusion It was found that the innovations proposed in the treatment are incipient in the daily work of nurses.

La voz flamenca del violín

Este proyecto representa una aproximación al flamenco desde la música clásica, y más concretamente desde el punto de vista violinístico. Se trata de una visión personal sobre los elementos técnicos e interpretativos a seguir para adentrarnos en la estilística flamenca. Ampliar los conocimientos musicales para así enriquecernos y crecer, tanto como personas como músicos. De la fusión musical emergen nuevos horizontes con los que poder expresarnos. Esto nos abre las puertas a la creatividad.

Bajo las estrellas del Romanticismo : un viaje a través de la noche

Con este trabajo he pretendido realizar un estudio aproximado a la música del período romántico cuya temática gira en torno al mundo de la noche. Lo he hecho a través de los compositores de música para piano más representativos de la época, con una breve pincelada a la música sinfónica y a las artes representativas. He pretendido demostrar cómo cada compositor reflejó su personalidad a través de un concepto tan abstracto y romántico como es el mundo de la noche.

Weak approximations. A Malliavin calculus approach

We introduce a variation of the proof for weak approximations that issuitable for studying the densities of stochastic processes which areevaluations of the flow generated by a stochastic differential equation on a random variable that maybe anticipating. Our main assumption is that the process and the initial random variable have to be smooth in the Malliavin sense. Furthermore if the inverse of the Malliavin covariance matrix associated with the process under consideration is sufficiently integrable then approximations fordensities and distributions can also be achieved. We apply theseideas to the case of stochastic differential equations with boundaryconditions and the composition of two diffusions.

The significance of distributive effects in social assessment of health care

In this paper we address the importance of distributive effects in the social valuation of QALY's. We propose a social welfarefunction that generalises the functions traditionally used in the health economic literature. The novelty is that, depending on the individual health gains, our function can representeither preferences for concentrating or preferences for spreading total gain or both together, an issue which has notbeen addressed until now. Based on an experiment, we observe that this generalisation provides a suitable approximation tothe sampled social preferences.