102 resultados para NEUTRON-STAR MATTER
Resumo:
In previous years, several publications have reported cases of infants presenting neurological and gastrointestinal symptoms after ingestion of star anise tea. Such teas are sometimes given in various cultures for the treatment of infant colic pains. In most cases, the cause of intoxication was contamination of Chinese star anise (Illicium verum) by Japanese star anise (Illicium anisatum). Indeed, the toxicity of Illicium anisatum, also known as Shikimi, is caused by its content in potent neurotoxins (anisatin, neoanisatin, and pseudoanisatin), due to their activity as non-competitive antagonists of GABA receptors. The main reasons explaining the frequent contaminations are the strong macroscopic resemblance of the 2 substances, as well as the fact that the fruits are often sold partially broken or in ground form. Therefore, in most cases, chemical analysis is required to determine the possible adulterations. CASE REPORT: A 2-month-old infant, in good general health, was brought to the emergency unit after 3 consecutive episodes of central cyanosis and tetany of the limbs with spontaneous recovery the same afternoon. The child was also very irritable, regurgitated a lot, and positioned himself in opisthotonos. Between these episodes, the neurological exam showed some perturbations (horizontal nystagmus and Bell's phenomenon, hypertony of the extensor muscles, and mild hypotony of the axial flexor muscles) with slow improvement over the following hours. The remaining clinical exam, the laboratory work (complete blood count, renal, hepatic, and muscular tests, capillary blood gas, plasmatic amino acids, and urinary organic acids), and the electroencephalogram findings were all normal. In the course of a detailed interview, the parents reported having given 3 bottles to their child, each one containing 200 mL of an infusion with 4 to 5 fruits of star anise, in the hours preceding the symptoms to relieve colic pains. The last seizure-like event took place approximately 8h after the last ingestion. We could prove the ingestion of anisatin, the toxic substance found in Japanese star anise, and the contamination of Chinese star anise by the Japanese species. Indeed, the anisatin analysis by liquid chromatography and mass spectroscopy (LC-MS) in a urine sample taken 22 h after the last infusion ingestion showed trace amounts of the substance. In another urine sample taken 33 h after ingestion, no anisatin could be detected. Furthermore, the analysis of the fruit sample gave an anisatin concentration of 7800 μg/kg while the maximum tolerance value in Switzerland is 1000 μg/kg. CONCLUSION: The evaluation of ALTE in infants should always include the possibility of intoxication. Star anise is generally considered a harmless medicine. Nevertheless, it can sometimes cause a severe intoxication resulting in various neurological and gastrointestinal symptoms. To prevent such events, not only the parents, but also the care personnel and pharmacists must be informed about the possible adverse effects caused either by the overdose of Chinese star anise or by the eventual contamination of herbal teas with Japanese star anise. A better control of the substances by the health authorities is also necessary.
Resumo:
An intercomparison of the response of different photon and neutron detectors was performed in several measurement positions around a spent fuel cask (type TN 12/2B) filled with 4 MOX and 8 UO2 15 x 15 PWR fuel assemblies at the nuclear power plant Gosgen (KKG) in Switzerland. The instruments used in the study were both active and passive, photon and neutron detectors calibrated either for ambient or personal dose equivalent. The aim of the measurement campaign was to compare the responses of the radiation instruments to routinely used detectors. It has been shown that especially the indications of the neutron detectors are strongly dependent on the neutron spectra around the cask due to their different energy responses. However, routinely used active photon and neutron detectors were shown to be reliable instruments. (C) 2012 Elsevier Ltd. All rights reserved.
Resumo:
After decades of management reforms in the public sector, questions on the impact of leader-ship behavior in public organizations have been attracting increasing attention. This paper investigates the relationship between transformational leadership behavior and organizational citizenship behavior as one major extra-role outcome of transformational leadership. Refer-ring to a growing body of research that shows the importance of public service values and employee identification in public administration research, we include public service motiva-tion and organizational goal clarification as mediating variables in our analysis. Structural equation modeling is applied as the method of analysis for a sample of 569 public managers at the local level of Switzerland. The findings of our study support the assumed indirect relation-ship between leadership and employee behavior and emphasize the relevance of public ser-vice values when analyzing leadership behavior in public sector organizations.
Resumo:
Using optimized voxel-based morphometry, we performed grey matter density analyses on 59 age-, sex- and intelligence-matched young adults with three distinct, progressive levels of musical training intensity or expertise. Structural brain adaptations in musicians have been repeatedly demonstrated in areas involved in auditory perception and motor skills. However, musical activities are not confined to auditory perception and motor performance, but are entangled with higher-order cognitive processes. In consequence, neuronal systems involved in such higher-order processing may also be shaped by experience-driven plasticity. We modelled expertise as a three-level regressor to study possible linear relationships of expertise with grey matter density. The key finding of this study resides in a functional dissimilarity between areas exhibiting increase versus decrease of grey matter as a function of musical expertise. Grey matter density increased with expertise in areas known for their involvement in higher-order cognitive processing: right fusiform gyrus (visual pattern recognition), right mid orbital gyrus (tonal sensitivity), left inferior frontal gyrus (syntactic processing, executive function, working memory), left intraparietal sulcus (visuo-motor coordination) and bilateral posterior cerebellar Crus II (executive function, working memory) and in auditory processing: left Heschl's gyrus. Conversely, grey matter density decreased with expertise in bilateral perirolandic and striatal areas that are related to sensorimotor function, possibly reflecting high automation of motor skills. Moreover, a multiple regression analysis evidenced that grey matter density in the right mid orbital area and the inferior frontal gyrus predicted accuracy in detecting fine-grained incongruities in tonal music.
Resumo:
The present study aims to identify organisational antecedents of public service motivation (PSM). Numerous research has been devoted to the identification of socio-demographic PSM antecedents, or to its outcomes. However, organisational antecedents are understudied thus far. In order to fill this research gap, we question whether human resources management practices, whether intrinsic or extrinsic ones, might be related to PSM. Drawing on person-environment fit theoretical assumptions, we depart from the idea that PSM may be developed or sustained by HRM practices, which might contribute to create an environment allowing public employees to fulfill their needs or personal aspirations. Based upon a survey in an important Swiss municipality (N = 859), our findings surprisingly highlight that extrinsic HRM practices are significantly related to PSM, whereas intrinsic ones are not. Furthermore, when taking into account work-related outcomes, such as job satisfaction and organisational commitment, there is evidence of full mediation effects towards extrinsic HRM practices from organisational commitment. Astonishingly, neither job satisfaction nor intrinsic HRM practices are significantly related to PSM.
Resumo:
This article analyzes if, and to what extent, the public service motivation (PSM) construct has an added value to explain work motivation in the public sector. In order to address the specificity of PSM when studying work motivation, the theoretical model underlying this empirical study compares PSM with two other explanatory factors: material incentives, such as performance-related pay, and team relations and support, such as recognition by superiors. This theoretical model is then tested with data collected in a national survey of 3,754 civil servants at the Swiss municipal level. Results of a structural equations model clearly show the relevance of PSM. They also provide evidence for the importance of socio-relational motivating factors, whereas material incentives play an anecdotal role.
Resumo:
The classical approach to predicting the geographical extent of species invasions consists of training models in the native range and projecting them in distinct, potentially invasible areas. However, recent studies have demonstrated that this approach could be hampered by a change of the realized climatic niche, allowing invasive species to spread into habitats in the invaded ranges that are climatically distinct from those occupied in the native range. We propose an alternative approach that involves fitting models with pooled data from all ranges. We show that this pooled approach improves prediction of the extent of invasion of spotted knapweed (Centaurea maculosa) in North America on models based solely on the European native range. Furthermore, it performs equally well on models based on the invaded range, while ensuring the inclusion of areas with similar climate to the European niche, where the species is likely to spread further. We then compare projections from these models for 2080 under a severe climate warming scenario. Projections from the pooled models show fewer areas of intermediate climatic suitability than projections from the native or invaded range models, suggesting a better consensus among modelling techniques and reduced uncertainty.
Resumo:
To ensure efficient energy supply to the high demanding brain, nutrients are transported into brain cells via specific glucose (GLUT) and monocarboxylate transporters (MCT). Mitochondrial dysfunction and altered glucose metabolism are thought to play an important role in the progression of neurodegenerative diseases, including multiple sclerosis (MS). Here, we investigated the cellular localization of key GLUT and MCT proteins in human brain tissue of non-neurological controls and MS patients. We show that in control brain tissue GLUT and MCT proteins were abundantly expressed in a variety of central nervous system cells, particularly in microglia and endothelial cells. In active MS lesions, GLUTs and MCTs were highly expressed in infiltrating leukocytes and reactive astrocytes. Astrocytes manifest increased MCT1 staining and maintain GLUT expression in inactive lesions, whereas demyelinated axons exhibit significantly reduced GLUT3 and MCT2 immunoreactivity in inactive lesions. Finally, we demonstrated that the co-transcription factor peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC-1α), an important protein involved in energy metabolism, is highly expressed in reactive astrocytes in active MS lesions. Overexpression of PGC-1α in astrocyte-like cells resulted in increased production of several GLUT and MCT proteins. In conclusion, we provide for the first time a comprehensive overview of key nutrient transporters in white matter brain samples. Moreover, our data demonstrate an altered expression of these nutrient transporters in MS brain tissue, including a marked reduction of axonal GLUT3 and MCT2 expression in chronic lesions, which may impede efficient nutrient supply to the hypoxic demyelinated axons thereby contributing to the ongoing neurodegeneration in MS. GLIA 2014;62:1125-1141.
Resumo:
BACKGROUND AND PURPOSE: MCI was recently subdivided into sd-aMCI, sd-fMCI, and md-aMCI. The current investigation aimed to discriminate between MCI subtypes by using DTI. MATERIALS AND METHODS: Sixty-six prospective participants were included: 18 with sd-aMCI, 13 with sd-fMCI, and 35 with md-aMCI. Statistics included group comparisons using TBSS and individual classification using SVMs. RESULTS: The group-level analysis revealed a decrease in FA in md-aMCI versus sd-aMCI in an extensive bilateral, right-dominant network, and a more pronounced reduction of FA in md-aMCI compared with sd-fMCI in right inferior fronto-occipital fasciculus and inferior longitudinal fasciculus. The comparison between sd-fMCI and sd-aMCI, as well as the analysis of the other diffusion parameters, yielded no significant group differences. The individual-level SVM analysis provided discrimination between the MCI subtypes with accuracies around 97%. The major limitation is the relatively small number of cases of MCI. CONCLUSIONS: Our data show that, at the group level, the md-aMCI subgroup has the most pronounced damage in white matter integrity. Individually, SVM analysis of white matter FA provided highly accurate classification of MCI subtypes.
Resumo:
Background: Previous magnetic resonance imaging (MRI) studies in young patients with bipolar disorder indicated the presence of grey matter concentration changes as well as microstructural alterations in white matter in various neocortical areas and the corpus callosum. Whether these structural changes are also present in elderly patients with bipolar disorder with long-lasting clinical evolution remains unclear. Methods: We performed a prospective MRI study of consecutive elderly, euthymic patients with bipolar disorder and healthy, elderly controls. We conducted a voxel-based morphometry (VBM) analysis and a tract-based spatial statistics (TBSS) analysis to assess fractional anisotropy and longitudinal, radial and mean diffusivity derived by diffusion tensor imaging (DTI). Results: We included 19 patients with bipolar disorder and 47 controls in our study. Fractional anisotropy was the most sensitive DTI marker and decreased significantly in the ventral part of the corpus callosum in patients with bipolar disorder. Longitudinal, radial and mean diffusivity showed no significant between-group differences. Grey matter concentration was reduced in patients with bipolar disorder in the right anterior insula, head of the caudate nucleus, nucleus accumbens, ventral putamen and frontal orbital cortex. Conversely, there was no grey matter concentration or fractional anisotropy increase in any brain region in patients with bipolar disorder compared with controls. Limitations: The major limitation of our study is the small number of patients with bipolar disorder. Conclusion: Our data document the concomitant presence of grey matter concentration decreases in the anterior limbic areas and the reduced fibre tract coherence in the corpus callosum of elderly patients with long-lasting bipolar disorder.