A statistical study of mammary vessel after breat cancer surgery

The following statistical study is about a series of quantitative response variables monitored three and six months after a breast operation. All patients that underwent a brest cancer operation from January 2003 untill June 2003 have been enrolled in the study. The number of patients observed is 38, but we have excluded from this study a patient for wich we do not have observed all investigated variables. The main issues involved here are: Descriptive analysis Temporal evolution of phenomena Effects of patient condition on the response variables In the following the three and six months variations of the response variables are labeled as (3) and (6) respectively, while the three to six month variation is marked as (6) (3).

Bayesian estimate of credit risk via MCMC with delayed rejection

We develop a Bayesian hierarchical logistic regression model to predict the credit risk of companiers classified in different sectors. Explanatory variables derived by experts from balance-sheets are included. Markov chain Monte Carlo (MCMC) methods are used to estimate the proposed model. In particular we show how the delaying rejection strategy outperforms the standart Metrtopolis-Hastings algorithm in terms of asymptotic efficiency of the resulting estimates. The advantages of our over others proposed in the literature are discussed and tested via cross-validation procedures.Asymptotic efficiency of MCMC estimates, Creadit risk, Default risk, Delayng rejection, Hierarchical logistic regression, Metropolis-Hastings algorithm

Variance reduction in MCMC

We propose a general purpose variance reduction technique for MCMC estimators. The idea is obtained by combining standard variance reduction principles known for regular Monte Carlo simulations (Ripley, 1987) and the Zero-Variance principle introduced in the physics literature (Assaraf and Caffarel, 1999). The potential of the new idea is illustrated with some toy examples and an application to Bayesian estimationMarkov chain Monte carlo, Metropolis-Hastings algorithm, Variance reduction, Zero-Variance principle

PM fractional machines adopting bonded magnets: effect of different magnetizations on the energetic performance

The adoption of Permanent Magnets in small brushless machines for automotive applications is becoming frequent. Some research on bonded magnets is being carried on to substitute the ferrites. In the paper the parallel and radial magnetizations are considered: the different process complexity levels are analyzed and the effects on the iron losses and the energetic performances are evaluated by means of a simulation analysis and its experimental validatio

Evaluation of the magnetization direction effects on ferrite PM brushless fractional machines

Permanent magnets are frequently adopted in small brushless machines for automotive applications. Normally anisotropic ferrites, but some research on bonded magnets is being carried on. Several types of magnetization can be proposed, involving different levels of complexity in the magnetization process. In the paper a comparison between parallel and radial magnetization is described, taking into account on one side the major complexity of the radial process and on the other the small power derating of the paralle

Gyrification brain abnormalities as predictors of outcome in anorexia nervosa.

Gyrification brain abnormalities are considered a marker of early deviations from normal developmental trajectories and a putative predictor of poor outcome in psychiatric disorders. The aim of this study was to explore cortical folding morphology in patients with anorexia nervosa (AN). A MRI brain study was conducted on 38 patients with AN, 20 fully recovered patients, and 38 healthy women. Local gyrification was measured with procedures implemented in FreeSurfer. Vertex-wise comparisons were carried out to compare: (1) AN patients and healthy women; (2) patients with a full remission at a 3-year longitudinal follow-up assessment and patients who did not recover. AN patients exhibited significantly lower gyrification when compared with healthy controls. Patients with a poor 3-year outcome had significantly lower baseline gyrification when compared to both healthy women and patients with full recovery at follow-up, even after controlling for the effects of duration of illness and gray matter volume. No significant correlation has been found between gyrification, body mass index, amount of weight loss, onset age, and duration of illness. Brain gyrification significantly predicted outcome at follow-up even after controlling for the effects of duration of illness and other clinical prognostic factors. Although the role of starvation in determining our findings cannot be excluded, our study showed that brain gyrification might be a predictor of outcome in AN. Further studies are needed to understand if brain gyrification abnormalities are indices of early neurodevelopmental alterations, the consequence of starvation, or the interaction between both factors

Linguistic embodiment in typical and atypical anorexia nervosa: Evidence from an image-word matching task

Objective: The integration of sensory, motor, and cognitive systems is embodied cognition, according to which mind and body are not separate and distinct, and our body (and our brain, as part of the body) contributes to determining our mental and cognitive processes. In spite of limited data available, Anorexia nervosa (AN) appears as a condition in which embodied cognition is altered, in particular, if we consider bodily sensations and visuospatial information processing. We aimed to evaluate the ability to correctly identify body parts and actions in both full (AN) and atypical AN (AAN), looking at the role of the underweight status. Method: A group of 143 females (AN = 45, AAN = 43, unaffected women = 55) was enrolled. All participants performed a linguistic embodied task to evaluate the association between a picture-showing a bodily action-and a written verb. Additionally, a subsample of 24 AN participants performed a retest after stable weight recovery. Results: Both AN and AAN demonstrated an abnormal ability to evaluate the picture-written verb associations, especially if the involved bodily effectors were the same in both stimuli (i.e., pictorial and verbal) and needed a longer response time. Conclusions: Specific embodied cognition linked to body schema seems to be impaired in persons with AN. The longitudinal analysis showed a difference between AN and AAN only in the underweight condition, suggesting the presence of an abnormal linguistic embodiment. More attention should be devoted to embodiment during AN treatment to improve bodily cognition, which might, in turn, diminish body misperception

Accuracy of self-assessment of real-life functioning in schizophrenia

A consensus has not yet been reached regarding the accuracy of people with schizophrenia in self-reporting their real-life functioning. In a large (n=618) cohort of stable, community-dwelling schizophrenia patients we sought to: (1) examine the concordance of patients' reports of their real-life functioning with the reports of their key caregiver; (2) identify which patient characteristics are associated to the differences between patients and informants. Patient-caregiver concordance of the ratings in three Specific Level of Functioning Scale (SLOF) domains (interpersonal relationships, everyday life skills, work skills) was evaluated with matched-pair t tests, the Lin's concordance correlation, Somers' D, and Bland-Altman plots with limits of agreement (LOA). Predictors of the patient-caregiver differences in SLOF ratings were assessed with a linear regression with multivariable fractional polynomials. Patients' self-evaluation of functioning was higher than caregivers' in all the evaluated domains of the SLOF and 17.6% of the patients exceeded the LOA, thus providing a self-evaluation discordant from their key caregivers. The strongest predictors of patient-caregiver discrepancies were caregivers' ratings in each SLOF domain. In clinically stable outpatients with a moderate degree of functional impairment, self-evaluation with the SLOF scale can become a useful, informative and reliable clinical tool to design a tailored rehabilitation program

The interplay among psychopathology, personal resources, context-related factors and real-life functioning in schizophrenia: stability in relationships after 4 years and differences in network structure between recovered and non-recovered patients

Improving real-life functioning is the main goal of the most advanced integrated treatment programs in people with schizophrenia. The Italian Network for Research on Psychoses previously explored, by using network analysis, the interplay among illness-related variables, personal resources, context-related factors and real-life functioning in a large sample of patients with schizophrenia. The same research network has now completed a 4-year follow-up of the original sample. In the present study, we used network analysis to test whether the pattern of relationships among all variables investigated at baseline was similar at follow-up. In addition, we compared the network structure of patients who were classified as recovered at follow-up versus those who did not recover. Six hundred eighteen subjects recruited at baseline could be assessed in the follow-up study. The network structure did not change significantly from baseline to follow-up, and the overall strength of the connections among variables increased slightly, but not significantly. Functional capacity and everyday life skills had a high betweenness and closeness in the network at follow-up, as they had at baseline, while psychopathological variables remained more peripheral. The network structure and connectivity of non-recovered patients were similar to those observed in the whole sample, but very different from those in recovered subjects, in which we found few connections only. These data strongly suggest that tightly coupled symptoms/dysfunctions tend to maintain each other's activation, contributing to poor outcome in schizophrenia. Early and integrated treatment plans, targeting variables with high centrality, might prevent the emergence of self-reinforcing networks of symptoms and dysfunctions in people with schizophrenia