1,720,970 research outputs found
Hippocampal volumes in patients with bipolar-schizophrenic spectrum disorders and their unaffected first-degree relatives
Full text linkBACKGROUND: schizophrenic and bipolar disorders are complex and disabling psychiatric diseases whose classical nosography and classification are still under challenging debate aiming to overcome the traditional “Kraepelinian Dichotomy”. For the past hundred years most clinical work and research in psychiatry has proceeded under the assumption that schizophrenia and bipolar disorderaredistinctentities with separate underlying disease processes and treatments. In more recent years there has been increasing evidence for phenomenological, biological and genetic overlap between the two disorders (Potash and Bienvenu 2009). Nowadays, the categorical approach to psychiatric nosography is in contrast with the recent neurobiological, neuropsychological and genetic findings in affective and schizophrenic disorders. Further, symptoms and signs constituting bipolar and schizophrenic disorders are continuously, not dichotomously, distributed; there may be no point of “real cleavage” (Phelps et al. 2008). This recognition has led some clinicians and researchers to call for a diagnostic model that, moving to a “dimensional perspective”, formally recognizes a continuous spectrum from schizophrenic to bipolar (and recurrent depressive) disorders. Kelsoe argued that the existing data coming from various fields of research in bipolar and schizophrenic disorders may best fit a model in which different set of genes predispose to overlapping phenotypes in a continuum. Given the apparent overlap of regions of the genome implicated in bipolar disorder with those for schizophrenia (Kelsoe 1999; Berrettini 2000), the data suggest the possibility that a common polygenic background predisposes to both bipolar disorder and schizophrenia, according to the so-called “multiple threshold model” (Kelsoe 2003). As highlighted by Craddock and Owen, the recent findings are compatible with a model of functional psychosis in which susceptibility to a spectrum of clinical phenotypes is under the influence of overlapping sets of genes, which, together with environmental and epigenetic factors, determine an individual’s expression of illness (Craddock and Owen 2005). A lot of interest is focusing on brain structural abnormalities in patients suffering from schizophrenia and bipolar disorder. A huge amount of neuroimaging studies has been published so far, however the literature is heterogeneous and there is still some degree of uncertainty concerning what key regions are involved in the pathogenesis of such disorders. Schizophrenia and Bipolar Disorder have a number of overlapping symptoms and risk factors, but it is not yet clear if the disorders are characterized by similar deviations in brain morphometry or whether any such deviations reflect the impact of shared susceptibility genes on brain structure. To date there is no consensus about whether, and to what extent, gray matter loss in Schizophrenia is mirrored in Bipolar Disorder and what is the effect of medication or other confounding factors. Studies in family members of patients, who share the risk of the disease but not the confounding factors, may help elucidate whether abnormalities in brain structures are shared by both illnesses.
AIM OF THE STUDY: to investigate hippocampal gray matter volume differences in a group of patients with bipolar-schizophrenic spectrum disorders, a group of their unaffected first-degree relatives, and a group of healthy control subjects.
METHODS: a total of 104 subjects - 36 schizophrenic or schizoaffective (SZ), 27 bipolar (BP), 2 major depression, 8 unaffected relatives (UR), and 31 healthy controls (HC) - underwent 1,5 T MRI scanning, with volumetric T1 3D acquisition protocol, at the Neuroradiology Unit of Conegliano Hospital. We calculate bilateral hippocampal gray matter volume (HV) and total cerebral volume (TCV) in a sample of 31 SZ, 27 BP, 8 UR and 26 HC, with a stereological method using ANALYZE 10.0 software.
RESULTS: we found statistically significant reductions in bilateral HV in the BP-SZ patients compared to HC; the direct comparison between patient groups identified statistically significant reduction in the right HV of SZ, but no significant differences for left HV or TCV (however statistical significance was lost after normalization); statistically significant reduction in the left HV and a trend towards statistical significance for right HV in the UR compared to HC (a trend towards statistically significant reduction in bilateral HV persisted after normalization).
CONCLUSION: it might be speculated that the alterations of the gray matter volume in the hippocampus highlighted in our study could be interpreted as a possible structural “biological marker” in the schizophrenic-bipolar spectrum
Theoretical and numerical methods for kinetic simulation of plasmas
No full textUnderstanding and simulating the dynamics of plasmas in Tokamak devices is a crucial aspect of the plasma physics research, especially with the upcoming ITER device. The development of numerical schemes that possess conservation laws over the vast time scale that covers the dynamics of charged particles in fusion plasmas is an intimidating yet a very important task. This thesis presents novel numerical and theoretical techniques to tackle this problem.
First, an overview of the kinetic theory, in particular the derivations of the Vlasov equation, the Fokker-Planck equation and the Vlasov-Maxwell equation in a variational setting, is given. The Euler-Poincar\'{e} reduction, which is a powerful mathematical tool that allows to derive the the Vlasov-Maxwell equations in a straightforward way, is presented as well.
A multi-species, marker based, structure-preserving numerical code for the Landau equation is presented. The code is able to preserve energy and momentum to machine precision and leverages GPU-computing to efficiently scale with the dimension of the system. The scheme was validated against relaxation, isotropization and thermalization theoretical estimates for different mass-ratio of the species, including a real electron-deuteron case, showing good agreement in all performed tests.
Finally, the problem of fast ions is tackled by introducing the Backward Monte Carlo (BMC) scheme. The approach aims at increasing the poor statistics of current Forward Monte Carlo simulations by integrating the probability of fast ions backward in time and taking into account deterministically the spread of the Monte Carlo collision operator. The scheme was implemented as a module of the orbit following code ASCOT5, enabling high performance simulations especially with modern supercomputers, and test cases with realistic plasma profiles, magnetic fields and wall geometries. The BMC scheme was applied to a realistic ASDEX Upgrade configuration of beam-ion distributions, with a Fast-Ion Loss Detector (FILD) placed near the divertor. The results shows a substantial increase of wall hits compared to a standard Forward Monte Carlo simulation
Clinical practice and nursing management of pre-operative skin or skeletal traction for hip fractures in elderly patients: a cross-sectional three-institution study
Full text linkBackground: Femoral fractures are a major healthcare problem worldwide. One of the most difficult issues is their preoperative care, which is still managed by either skeletal or skin traction in some countries, including Italy. These issues are discussed and compared with the contemporary literature.
Objective: This study aims to analyse the distribution of these treatment options within the orthopaedic community and the reasons for their use, as well as to identify how this may impact nursing care in terms of pain management, hygiene care, venous thromboembolism (VTE)prophylaxis and prevention of pressure ulcers.
Design: For this cross-sectional study, a 12-item survey was administered to the nursing staff, consultants and residents of the Orthopaedic Units in three different hospitals in NorthEastern Italy. The questionnaire investigated the routine use of skeletal or skin traction for the preoperative management of hip fractures in those settings.
Findings: 136 surveys were completed, providing a response rate of 87.74%. Preoperative traction for hip fractures was still in use in the three hospitals, mainly applied by experienced surgeons for subtrochanteric fractures. Pain management, VTE and pressure ulcer prevention were perceived as worse only with skeletal traction, while hygiene was described as more difficult with both skeletal and skin traction.
Conclusions and recommendations: Based on the data and the literature revision, skin or skeletal traction for patients with proximal femoral fractures should be discouraged as standard practice. This is supported widely in the international literature, and consideration of knowledge translation strategies should be made to refine current practice in these settings
Predictors of early failure of the cannulated screw system in patients, 65 years and older, with non-displaced femoral neck fractures
Full text linkBackground: Hip fractures represent the most common injury and the main cause of morbidity and mortality among patients 65 years and older. About 20% of all femoral neck fractures (FNFs) are non-displaced or valgus impacted, for which internal fixation with the cannulated screws system (CSS) is indicated. Aims: The aim of this study was to identify predictors of early failure of CSS. Methods: Patients with non-displaced FNFs (Garden type I and II) treated operatively using the CSS were enrolled. Their characteristics, Pauwels angle, and posterior tilt were assessed and related with outcomes. The primary outcome was fixation failure within 6 months. Results: 259 patients were included with a mean age of 81.44 years. Most patients were female with ASA 3. The majority of fractures were classified as Garden I and Pauwels I. On average, Pauwels angle was 27°, while posterior tilt was 12°. A linear correlation between Pauwels angle and posterior tilt was found; the failure rate was 9.7%. Using the adjusted Cox competing risk regression analysis, posterior tilt was found to be independently associated with failure rate (sub-distribution hazard ratio or SHR 1.14 [95% CI 1.05–1.24], p = 0.0020). A posterior tilt greater than 18° resulted predictive of failure. The 1-year mortality rate was 12%. Conclusions: Non-displaced Garden type II fractures, Pauwels type II or III fractures, and a posterior tilt greater than 18° represent radiographic predictors of CSS early failure in the elderly. Level of evidence: Level IV, retrospective cohort study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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