This paper describes the design and setup of different measuring systems for the calibration of both voltage and current transducers which are recently developed at VSL, PTB, and TUBITAK. The output ...levels of non-conventional transducers are adapted to traditional levels using step-up and step-down converters so that they can be measured using traditional measurement bridges. Verification and performance of a recently developed commercial transformer test set is investigated. The reference measuring systems are developed within the frame of the European project "FUTURE GRID - Non-conventional voltage and current sensors for future power grids".
This paper describes the setup of sampling-based high voltage measuring systems for reactive compensation components recently developed at VTT and PTB. First measurements show an agreement within 10 ...-4 between both measuring systems. Both a phantom power source emulating reactors and capacitors with adjustable losses, and a set of real reactive components were measured. Measurements were performed with stable 53 Hz frequency and variable 50 Hz power frequency. The measuring systems are developed within the frame of the European project "ELPOW - Metrology for the Electrical Power Industry".
Typically small animal radiological images are obtained after placing the animal in the center of the imaging device using beds or platforms, and then adjusting the position after obtaining a scout ...image. Such a process does not permit the reproducible visualization of the same anatomical plane with repeated examinations. We have developed a device that allows stereotaxic placement of an animal in precisely the same position for repeated examinations. The instrument incorporates a full range of physiological monitoring and life support systems including temperature control, anesthesia delivery and respiratory monitoring. Using magnetic resonance imaging (MRI), the accuracy and reliability of this device is demonstrated in a rat traumatic brain injury (TBI) model.
A number of recent studies have challenged the hypothesis that patients with obsessive-compulsive disorder (OCD) display global memory deficits. An alleviated form of the memory deficit hypothesis ...posits that OCD patients share deficits to vividly recall memory episodes. According to the latter view, checking rituals can be understood as counter-productive coping strategies to "enrich" memory episodes in order to make them more distinctive. A source memory task was administered to 27 OCD (17 checkers) and 51 healthy participants. Along with confidence judgments, a remember-know procedure was employed to assess whether OCD patients display problems with conscious/vivid recollection. Patients with or without checking compulsions did not exhibit differences to controls on source memory accuracy and meta-memory. Patients forgot more self-generated items, which, however, was related to comorbid depressive but not OCD symptoms. Findings challenge the ubiquity of memory deficits in OCD. To account for the inconclusive pattern of results in the literature, it is suggested that patients mistrust their memories and adopt checking rituals only when perceived responsibility is inflated.
The focus of this study is on the effect of form deviations of a partial journal bearing's sliding surface on the friction force in mixed lubrication conditions. The measured friction varied ...considerably when the bearing was rotated in the opposite direction at the same speed and normal load. This unexpected observation motivated the presented simulation study. The overall form deviations of the surface of the test bearing were measured with white light interferometry and used as simulation input. The two-scale simulation approach considers the effect of the surface roughness on a microscopic and the global bearing geometry with the surface form deviations on a macroscopic scale. Simulation results show that the surface form deviations can have a noticeable effect on the pressure distribution of the lubricant and hence on the size of the asperity contact area which leads to the differences in friction. The influence of the lubricant viscosity, the clearance gap and the surface roughness were analysed in a parametric simulation study. Results show that the clearance and the surface roughness control the impact of the surface form deviations on the friction force. All in all, the results show the necessity to include all scales of surface form deviations in the simulation of journal bearings in a mixed lubrication regime.
•The impact of roundness deviations of a journal bearing on mixed friction is analyzed with simulation and experiment.•The measured roundness deviations considered in simulation influence the computed hydrodynamic pressure build-up.•Comparison shows a good coincidence of simulation and experiment.
Objective: To evaluate brain metabolism in subjects with partial ornithine transcarbamylase deficiency (OTCD) utilizing
1H MRS.
Methods: Single-voxel
1H MRS was performed on 25 medically-stable ...adults with partial OTCD, and 22 similarly aged controls. Metabolite concentrations from frontal and parietal white matter (FWM, PWM), frontal gray matter (FGM), posterior cingulate gray matter (PCGM), and thalamus (tha) were compared with controls and IQ, plasma ammonia, glutamine, and disease severity.
Results: Cases ranged from 19 to 59 years; average 34 years; controls ranged from 18 to 59 years; average 33 years. IQ scores were lower in cases (full scale 111 vs. 126; performance IQ 106 vs. 117). Decreased myoinositol (mI) in FWM (
p
=
0.005), PWM (
p
<
0.001), PCGM (
p
=
0.003), and tha (
p
=
0.004), identified subjects with OTCD, including asymptomatic heterozygotes. Glutamine (gln) was increased in FWM (
p
<
0.001), PWM (
p
<
0.001), FGM (
p
=
0.002), and PCGM (
p
=
0.001). Disease severity was inversely correlated with mI in PWM (
r
=
−0.403;
p
=
0.046) and directly correlated with gln in PCGM (
r
=
0.548;
p
=
0.005).
N-Acetylaspartate (NAA) was elevated in PWM (
p
=
0.002); choline was decreased in FWM (
p
=
0.001) and tha (
p
=
0.002). There was an inverse relationship between mI and gln in cases only. Total buffering capacity (measured by mI/mI
+
gln ratio, a measure of total osmolar capacity) was inversely correlated with disease severity in FWM (
r
=
−0.479;
p
=
0.018), PWM (
r
=
−0.458;
p
=
0.021), PCGM (
r
=
−0.567;
p
=
0.003), and tha (
r
=
−0.345;
p
=
0.037).
Conclusion: Brain metabolism is impaired in partial OTCD. Depletion of mI and total buffering capacity are inversely correlated with disease severity, and serve as biomarkers.
Silver-Russell syndrome (SRS) is a heterogeneous disorder associated with intrauterine and postnatal growth restriction, body asymmetry, a relative macrocephaly, a characteristic triangular face and ...further dysmorphisms. In about 50% of patients, genetic/epigenetic alterations can be detected: >38% of patients show a hypomethylation of the IGF2/H19 imprinting region in 11p15, whereas the additional 10% carry a maternal uniparental disomy of chromosome 7. In single cases, cytogenetic aberrations can be detected. Nevertheless, there still remain 50% of SRS patients without known genetic/epigenetic alterations. To find out whether submicroscopic imbalances contribute to the aetiology of SRS, 20 idiopathic SRS patients were screened with the Affymetrix GeneChip Human Mapping 500 K array set. Apart from known apathogenic copy number variations, we identified one patient with a 12q14 microdeletion. The 12q14 microdeletion syndrome is characterised by dwarfism but it additionally includes mental retardation and osteopoikilosis. The deletion in our patient is smaller than those in the 12q14 microdeletion carriers but it also affects the LEMD3 and the HMGA2 genes. LEMD3 haploinsufficiency and point mutations have been previously associated with osteopoikilosis but radiographs of our patient at the age of 16 years did not reveal any hint for osteopoikilosis lesions. Haploinsufficiency of HMGA2 is probably responsible for aberrant growth in 12q14 microdeletion syndrome. However, in this study, a general role of HMGA2 mutations for SRS was excluded by sequencing of 20 idiopathic patients. In conclusion, our results exclude a common cryptic chromosomal imbalance in idiopathic SRS patients but show that chromosomal aberrations are relevant in this disease. Thus, molecular karyotyping is indicated in SRS and should be included in the diagnostic algorithm.
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