260 research outputs found

    Оцінка екологічного стану водосховищ гідроенергетичного призначення на р. Південний Буг за гідрогеологічними показниками

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    Проаналізовано особливості гідробіологічних угрупувань водосховищ гідроенергетичного призначення р.Південний Буг. Дослідження проведено за такими показниками: видовий склад, кількість, біомаса, трофічні характеристики, індекс сапробності за Пантле-Букком, за Балушкіною (для угрупувань бентосу), індекс видового різноманіття Шеннона окремо за чисельністю та біомасою, індекс Пареле, рибопродуктивність водосховищ

    An improved nearest neighbor method for the estimation of the gamma photon entry point in monolithic scintillator detectors for PET

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    Several improvements of the k-nearest neighbor (k-NN) method for the determination of the entry point (x, y) of a gamma photon in a monolithic scintillator PET detector have been investigated with the aim to obtain better spatial resolution and/or to enable faster detector calibration by reducing the amount of required reference data and by allowing for calibrating with a line source. These methods were tested on a dataset measured with a SiPM-array-based monolithic LYSO detector. It appears that 10% to 25% better spatial resolution can be obtained compared to the standard approach. Moreover, some of the improved methods using two orders of magnitude less reference data, yield essentially the same spatial resolution as the standard method, which reduces the time needed for calibration as well as entry point computation. Finally, line source calibration is shown to be possible with some of the methods, yielding better results than the standard method and allowing much faster and easier collection of the reference data.</p

    The effect of three-dimensional visualisation on performance in endoscopic sinus surgery:A clinical training study using surgical navigation for movement analysis in a randomised crossover design

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    Objectives: Endoscopic imaging techniques and endoscopic endonasal surgery (EES) expertise have evolved rapidly. Only few studies have assessed the effect of three-dimensional (3D) endoscopy on endoscopic sinus surgery (ESS). The present study aimed to objectively and subjectively assess the additional value of 3D high-definition (HD) endoscopy in ESS. Design: A randomized crossover study of endoscopic surgery performance, using five ESS tasks of varying complexity, performed on Thiel embalmed human specimens. Setting: Simulated surgical environment. Participants: Thirty participants, inexperienced in ESS. Main outcome measures: Performance was assessed using video imaging, surgical navigation and questionnaires. Main outcome measures were as follows: efficiency (defined by time to task completion), distance covered inside the nose, average velocity towards target, accuracy (measured by error rate), and subjective assessment of endoscope characteristics. Results: During ESS tasks, both efficiency and accuracy did not differ significantly between 2D HD and 3D HD endoscopy. Subjectively, imaging characteristics of the 3D HD endoscope were rated significantly better. Conclusions: ESS performance of inexperienced participants was not significantly improved by the use of 3D HD endoscopy during ESS tasks, although imaging characteristics of the 3D HD endoscope were rated significantly better. Surgical field characteristics and surgical techniques are likely to influence any additional value of 3D HD endoscopy

    Axon-Myelin Unit Blistering as Early Event in MS Normal Appearing White Matter

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    Objective: Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease of unknown etiology. Although the prevalent view regards a CD4 +-lymphocyte autoimmune reaction against myelin at the root of the disease, recent studies propose autoimmunity as a secondary reaction to idiopathic brain damage. To gain knowledge about this possibility we investigated the presence of axonal and myelinic morphological alterations, which could implicate imbalance of axon-myelin units as primary event in MS pathogenesis. Methods: Using high resolution imaging histological brain specimens from patients with MS and non-neurological/non-MS controls, we explored molecular changes underpinning imbalanced interaction between axon and myelin in normal appearing white matter (NAWM), a region characterized by normal myelination and absent inflammatory activity. Results: In MS brains, we detected blister-like swellings formed by myelin detachment from axons, which were substantially less frequently retrieved in non-neurological/non-MS controls. Swellings in MS NAWM presented altered glutamate receptor expression, myelin associated glycoprotein (MAG) distribution, and lipid biochemical composition of myelin sheaths. Changes in tethering protein expression, widening of nodes of Ranvier and altered distribution of sodium channels in nodal regions of otherwise normally myelinated axons were also present in MS NAWM. Finally, we demonstrate a significant increase, compared with controls, in citrullinated proteins in myelin of MS cases, pointing toward biochemical modifications that may amplify the immunogenicity of MS myelin. Interpretation: Collectively, the impaired interaction of myelin and axons potentially leads to myelin disintegration. Conceptually, the ensuing release of (post-translationally modified) myelin antigens may elicit a subsequent immune attack in MS. ANN NEUROL 2021;89:711–725

    A comparison of national approaches to setting ecological status boundaries in phytobenthos assessment for the European Water Framework Directive: results of an intercalibration exercise

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    The European Union (EU)'s Water Framework Directive (WFD) requires that all Member States participate in intercalibration exercises in order to ensure that ecological status concepts and assessment levels are consistent across the EU. This paper describes one such exercise, performed by the countries in the Central/Baltic Geographical Intercalibration Group stretching from Ireland in the west to Estonia in the east and from the southern parts of Scandinavia to the northern regions of Spain and Italy (but excluding alpine regions, which were intercalibrated separately). In this exercise, methods used to measure ecological status of rivers using benthic diatoms were compared. Ecological status is estimated as the ratio between the observed value of a biological element and the value expected in the absence of significant human impact. Approaches to defining the 'reference sites', from which these 'expected' values were derived, varied from country to country. Minimum criteria were established as part of the exercise but there was still considerable variation between national reference values, reflecting typological differences that could not be resolved during the exercise. A simple multimetric index was developed to compare boundary values using two widely used diatom metrics. Boundary values for high/good status and good/moderate status set by each participant were converted to their equivalent values of this intercalibration metric using linear regression. Variation of ±0.05 EQR units around the median value was considered to be acceptable and the exercise provided a means for those Member States who fell significantly above or below this line to review their approaches and, if necessary, adjust their boundaries

    Collaborative stepped care for anxiety disorders in primary care: aims and design of a randomized controlled trial

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    Background. Panic disorder (PD) and generalized anxiety disorder (GAD) are two of the most disabling and costly anxiety disorders seen in primary care. However, treatment quality of these disorders in primary care generally falls beneath the standard of international guidelines. Collaborative stepped care is recommended for improving treatment of anxiety disorders, but cost-effectiveness of such an intervention has not yet been assessed in primary care. This article describes the aims and design of a study that is currently underway. The aim of this study is to evaluate effects and costs of a collaborative stepped care approach in the primary care setting for patients with PD and GAD compared with care as usual. Methods/design. The study is a two armed, cluster randomized controlled trial. Care managers and their primary care practices will be randomized to deliver either collaborative stepped care (CSC) or care as usual (CAU). In the CSC group a general practitioner, care manager and psychiatrist work together in a collaborative care framework. Stepped care is provided in three steps: 1) guided self-help, 2) cognitive behavioral therapy and 3) antidepressant medication. Primary care patients with a DSM-IV diagnosis of PD and/or GAD will be included. 134 completers are needed to attain sufficient power to show a clinically significant effect of 1/2 SD on the primary outcome measure, the Beck Anxiety Inventory (BAI). Data on anxiety symptoms, mental and physical health, quality of life, health resource use and productivity will be collected at baseline and after three, six, nine and twelve months. Discussion. It is hypothesized that the collaborative stepped care intervention will be more cost-effective than care as usual. The pragmatic design of this study will enable the researchers to evaluate what is possible in real clinical practice, rather than under ideal circumstances. Many requirements for a high quality trial are being met. Results of this study will contribute to treatment options for GAD and PD in the primary care setting. Results will become available in 2011. Trial registration. NTR1071

    Medical conditions in autism spectrum disorders

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    Autism spectrum disorder (ASD) is a behaviourally defined syndrome where the etiology and pathophysiology is only partially understood. In a small proportion of children with the condition, a specific medical disorder is identified, but the causal significance in many instances is unclear. Currently, the medical conditions that are best established as probable causes of ASD include Fragile X syndrome, Tuberous Sclerosis and abnormalities of chromosome 15 involving the 15q11-13 region. Various other single gene mutations, genetic syndromes, chromosomal abnormalities and rare de novo copy number variants have been reported as being possibly implicated in etiology, as have several ante and post natal exposures and complications. However, in most instances the evidence base for an association with ASD is very limited and largely derives from case reports or findings from small, highly selected and uncontrolled case series. Not only therefore, is there uncertainty over whether the condition is associated, but the potential basis for the association is very poorly understood. In some cases the medical condition may be a consequence of autism or simply represent an associated feature deriving from an underlying shared etiology. Nevertheless, it is clear that in a growing proportion of individuals potentially causal medical conditions are being identified and clarification of their role in etio-pathogenesis is necessary. Indeed, investigations into the causal mechanisms underlying the association between conditions such as tuberous sclerosis, Fragile X and chromosome 15 abnormalities are beginning to cast light on the molecular and neurobiological pathways involved in the pathophysiology of ASD. It is evident therefore, that much can be learnt from the study of probably causal medical disorders as they represent simpler and more tractable model systems in which to investigate causal mechanisms. Recent advances in genetics, molecular and systems biology and neuroscience now mean that there are unparalleled opportunities to test causal hypotheses and gain fundamental insights into the nature of autism and its development

    Diversity among Bi-ethnic students and differences in educational outcomes and social functioning

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    The number of bi-ethnic children is increasing. The focus of this study is on bi-ethnic students in the Netherlands with one parent with an ethnic majority background and one parent with an ethnic minority background. Most studies that have investigated educational outcomes and social functioning in school for bi-ethnic students have not focused on the diversity within this group. In this study, we described the demographic, social and cultural diversity among bi-ethnic students and examined whether, in particular, ethnic background and gender of the migrant parent were related to the educational outcomes and social functioning of bi-ethnic students. Data on a total of 653 sixth grade bi-ethnic students (age 11–12) in primary education of the national Dutch cohort study (COOL5−18) were used in this study. To analyse the relationship between the ethnic background and gender of the migrant parent and the educational outcomes and social functioning among bi-ethnic students, multivariate multilevel analyses were performed. The research findings indicate that bi-ethnic students differ demographically, socially and culturally in a manner dependent on ethnic background and gender of the migrant parent. We also found that the ethnic background and the gender of the migrant parent were related to cognitive outcomes, social-emotional functioning and citizenship competences. When trying to understand and support bi-ethnic students, we must consider the diversity among them
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