251 research outputs found

    A global digital image correlation enhanced full-field bulge test method

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    The miniature bulge test is a known method for characterizing the full stress-strain response of freestanding thin films. However, some discrepancies between quantitative results in the literature may be attributed to erroneous assumptions on the bulge shape. In this research, a specialized global Digital Image Correlation technique is developed that circumvents the need for bulge shape assumptions by correlating directly high-resolution profilometry maps of bulged membranes to yield full-field continuous displacement maps, from which local strain maps can be computed. Additionally, local curvature maps are also derived

    The Measurement of Language Lateralization with Functional Transcranial Doppler and Functional MRI: A Critical Evaluation

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    Cerebral language lateralization can be assessed in several ways. In healthy subjects, functional MRI (fMRI) during performance of a language task has evolved to be the most frequently applied method. Functional transcranial Doppler (fTCD) may provide a valid alternative, but has been used rarely. Both techniques have their own strengths and weaknesses and as a result may be applied in different fields of research. Until now, only one relatively small study (n = 13) investigated the correlation between lateralization indices (LIs) measured by fTCD and fMRI and showed a remarkably high correlation. To further evaluate the correlation between LIs measured with fTCD and fMRI, we compared LIs of 22 healthy subjects (12 left- and 10 right-handed) using the same word generation paradigm for the fTCD as for the fMRI experiment. LIs measured with fTCD were highly but imperfectly correlated with LIs measured with fMRI (Spearman's rho = 0.75, p < 0.001). The imperfectness of the correlation can partially be explained by methodological restrictions of fMRI as well as fTCD. Our results suggest that fTCD can be a valid alternative for fMRI to measure lateralization, particularly when costs or mobility are important factors in the study design

    Забезпечення розвитку інноваційності промислових підприємств при активізації інтелектуального капіталу суспільства

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    Проаналізовано стан і умови інноваційної діяльності підприємств в Україні. Досліджено проблеми неефективності державної політики в економічній сфері щодо розвитку інноваційності промислових підприємств. Розроблено пропозиції з удосконалення структури і напрямів діяльності державної політики щодо розвитку інноваційності промислових підприємств при активізації інтелектуального капіталу суспільства.Проанализированы состояние и условия инновационной деятельности предприятий в Украине. Исследованы проблемы неэффективности государственной политики в экономической сфере относительно развития инновационности промышленных предприятий. Разработаны предложения по усовершенствованию структуры и направлений деятельности государственной политики относительно развития инновационности промышленных предприятий при активизации интеллектуального капитала.The state and terms of innovative activity of enterprises in Ukraine are analyzed. Problems of inefficiency of public policy are investigated in an economic sphere in relation to innovativeness development of industrial enterprises. Suggestions for the improvement of structure and directions public policy activity in relation to innovativeness development of the industrial enterprises during activation of the society intellectual capital are worked out

    Human Fronto-Tectal and Fronto-Striatal-Tectal Pathways Activate Differently During Anti-Saccades

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    Almost all cortical areas in the vertebrate brain take part in recurrent connections through the subcortical basal ganglia (BG) nuclei, through parallel inhibitory and excitatory loops. It has been suggested that these circuits can modulate our reactions to external events such that appropriate reactions are chosen from many available options, thereby imposing volitional control over behavior. The saccade system is an excellent model system to study cortico-BG interactions. In this study two possible pathways were investigated that might regulate automaticity of eye movements in the human brain; the cortico-tectal pathway, running directly between the frontal eye fields (FEF) and superior colliculus (SC) and the cortico-striatal pathway from the FEF to the SC involving the caudate nucleus (CN) in the BG. In an event-related functional magnetic resonance imaging (fMRI) paradigm participants made pro- and anti-saccades. A diffusion tensor imaging (DTI) scan was made for reconstruction of white matter tracts between the FEF, CN and SC. DTI fiber tracts were used to divide both the left and right FEF into two sub-areas, projecting to either ipsilateral SC or CN. For each of these FEF zones an event-related fMRI timecourse was extracted. In general activity in the FEF was larger for anti-saccades. This increase in activity was lateralized with respect to anti-saccade direction in FEF zones connected to the SC but not for zones only connected to the CN. These findings suggest that activity along the contralateral FEF–SC projection is responsible for directly generating anti-saccades, whereas the pathway through the BG might merely have a gating function withholding or allowing a pro-saccade

    Conversion of daily pegvisomant to weekly pegvisomant combined with long-acting somatostatin analogs, in controlled acromegaly patients

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    The efficacy of combined treatment in active acromegaly with both long-acting somatostatin analogs (SRIF) and pegvisomant (PEG-V) has been well established. The aim was to describe the PEG-V dose reductions after the conversion from daily PEG-V to combination treatment. To clarify the individual beneficial and adverse effects, in two acromegaly patients, who only normalized their insulin like growth factor (IGF-I) levels with high-dose pegvisomant therapy. We present two cases of a 31 and 44 years old male with gigantism and acromegaly that were controlled subsequently by surgery, radiotherapy, SRIF analogs and daily PEG-V treatment. They were converted to combined treatment of monthly SSA and (twice) weekly PEG-V. High dose SSA treatment was added while the PEG-V dose was decreased during carful monitoring of the IGF-I. After switching from PEG-V monotherapy to SRIF analogs plus pegvisomant combination therapy IGF-I remained normal. However, the necessary PEG-V dose, to normalize IGF-I differed significantly between these two patients. One patient needed twice weekly 100 mg, the second needed 60 mg once weekly on top of their monthly lanreotide Autosolution injections of 120 mg. The weekly dose reduction was 80 and 150 mg. After the introducing of lanreotide, fasting glucose and glycosylated haemoglobin concentrations increased. Diabetic medication had to be introduced or increased. No changes in liver tests or in pituitary adenoma size were observed. In these two patients, PEG-V in combination with long-acting SRIF analogs was as effective as PEG-V monotherapy in normalizing IGF-I levels, although significant dose-reductions in PEG-V could be achieved. However, there seems to be a wide variation in the reduction of PEG-V dose, which can be obtained after conversion to combined treatment

    Celio (\u2705), Orkand (\u2707) Named Up and Coming Leaders

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    BackgroundAlthough auditory verbal hallucinations (AVH) are a core symptom of schizophrenia, they also occur in non-psychotic individuals, in the absence of other psychotic, affective, cognitive and negative symptoms. AVH have been hypothesized to result from deviant integration of inferior frontal, parahippocampal and superior temporal brain areas. However, a direct link between dysfunctional connectivity and AVH has not yet been established. To determine whether hallucinations are indeed related to aberrant connectivity, AVH should be studied in isolation, for example in non-psychotic individuals with AVH.MethodResting-state connectivity was investigated in 25 non-psychotic subjects with AVH and 25 matched control subjects using seed regression analysis with the (1) left and (2) right inferior frontal, (3) left and (4) right superior temporal and (5) left parahippocampal areas as the seed regions. To correct for cardiorespiratory (CR) pulsatility rhythms in the functional magnetic resonance imaging (fMRI) data, heartbeat and respiration were monitored during scanning and the fMRI data were corrected for these rhythms using the image-based method for retrospective correction of physiological motion effects RETROICOR.ResultsIn comparison with the control group, non-psychotic individuals with AVH showed increased connectivity between the left and the right superior temporal regions and also between the left parahippocampal region and the left inferior frontal gyrus. Moreover, this group did not show a negative correlation between the left superior temporal region and the right inferior frontal region, as was observed in the healthy control group.ConclusionsAberrant connectivity of frontal, parahippocampal and superior temporal brain areas can be specifically related to the predisposition to hallucinate in the auditory domain.</jats:sec

    Altered thalamocortical structural connectivity in persons with schizophrenia and healthy siblings

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    Schizophrenia has long been framed as a disorder of altered brain connectivity, with dysfunction in thalamocortical circuity potentially playing a key role in the development of the illness phenotype, including psychotic symptomatology and cognitive impairments. There is emerging evidence for functional and structural hypoconnectivity between thalamus and prefrontal cortex in persons with schizophrenia spectrum disorders, as well as hyperconnectivity between thalamus and sensory and motor cortices. However, it is unclear whether thalamocortical dysconnectivity is a general marker of vulnerability to schizophrenia or a specific mechanism of schizophrenia pathophysiology. This study aimed to answer this question by using diffusion-weighted imaging to examine thalamocortical structural connectivity in 22 persons with schizophrenia or schizoaffective disorder (SZ), 20 siblings of individuals with a schizophrenia spectrum disorder (SIB), and 44 healthy controls (HC) of either sex. Probabilistic tractography was used to quantify structural connectivity between thalamus and six cortical regions of interest. Thalamocortical structural connectivity was compared among the three groups using cross-thalamic and voxel-wise approaches. Thalamo-prefrontal structural connectivity was reduced in both SZ and SIB relative to HC, while SZ and SIB did not differ from each other. Thalamo-motor structural connectivity was increased in SZ relative to SIB and HC, while SIB and HC did not differ from each other. Hemispheric differences also emerged in thalamic connectivity with motor, posterior parietal, and temporal cortices across all groups. The results support the hypothesis that altered thalamo-prefrontal structural connectivity is a general marker of vulnerability to schizophrenia, whereas altered connectivity between thalamus and motor cortex is related to illness expression or illness-related secondary factors

    Non-invasive brain stimulation in schizophrenia:hallucinations and negative symptoms

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    BACKGROUND: New approaches are needed in the treatment of characteristic symptoms of schizophrenia such as hallucinations and negative symptoms. Non-invasive brain stimulation can make a useful contribution.&lt;br/&gt; AIM: To discuss the published evidence regarding efficacy and safety of repetitive transcranial magnetic stimulation (rtms) and transcranial direct current stimulation (tdcs) when used in the treatment of auditory verbal hallucinations and negative symptoms.&lt;br/&gt; METHOD: We review and discuss recent meta-analyses and we analyse relevant factors.&lt;br/&gt; RESULTS: On average, when compared to sham-stimulation, rtms was found to have a significant effect on hallucinations and negative symptoms. Nevertheless, the results of some studies were variable and some studies did not report any improvement. There are indications that some factors such as age and distance between scalp and cortex may influence efficiency. There were only a few studies relating to the use of tdcs and none of these reported a clear effect.&lt;br/&gt; CONCLUSION: There is reasonable evidence that rtms is an efficient treatment for hallucinations and negative symptoms, although some variable results have been reported. There is insufficient evidence for conclusions to be drawn about the efficacy of tdcs for the treatment of hallucinations and negative symptoms. However, both simulation methods are safe and largely without side-effects.</p

    Altered effective connectivity within an oculomotor control network in individuals with schizophrenia

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    Rapid inhibition or modification of actions is a crucial cognitive ability, which is impaired in persons with schizophrenia (SZP). Primate neurophysiology studies have identified a network of brain regions that subserves control over gaze. Here, we examine effective connectivity within this oculomotor control network in SZP and healthy controls (HC). During fMRI, participants performed a stop-signal task variant in which they were instructed to saccade to a visual target (no-step trials) unless a second target appeared (redirect trials); on redirect trials, participants were instructed to inhibit the planned saccade and redirect to the new target. We compared functional responses on redirect trials to no-step trials and used dynamic causal modelling (DCM) to examine group differences in network effective connectivity. Behaviorally, SZP were less efficient at inhibiting, which was related to their employment status. Compared to HC, they showed a smaller difference in activity between redirect trials and no-step trials in frontal eye fields (FEF), supplementary eye fields (SEF), inferior frontal cortex (IFC), thalamus, and caudate. DCM analyses revealed widespread group differences in effective connectivity across the task, including different patterns of self-inhibition in many nodes in SZP. Group differences in how effective connectivity was modulated on redirect trials revealed differences between the FEF and SEF, between the SEF and IFC, between the superior colliculus and the thalamus, and self-inhibition within the FEF and caudate. These results provide insight into the neural mechanisms of inefficient inhibitory control in individuals with schizophrenia
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