83 research outputs found
The Perfect Laplace Operator for Non-Trivial Boundaries
The application of Renormalization Group (RG) methods to find perfect
discretizations of partial differential equations is a promising but little
investigated approach. We calculate the classically perfect fixed-point Laplace
operator for boundaries of non-trivial shape analytically and numerically and
present a parametrization that can be used for solving the Poisson equation.Comment: Poster for Lattice 2000 (Improvement), 5 page
Stimulation induced variability of pulse plethysmography does not discriminate responsiveness to intubation
Background. Hypnotic depth but not haemodynamic response to painful stimulation can be measured with various EEG-based anaesthesia monitors. We evaluated the variation of pulse plethysmography amplitude induced by an electrical tetanic stimulus (PPG variation) as a potential measure for analgesia and predictor of haemodynamic responsiveness during general anaesthesia. Methods. Ninety-five patients, ASA I or II, were randomly assigned to five groups [Group 1: bispectral index (BIS) (range) 40-50, effect site remifentanil concentration 1 ng ml−1;Group 2: BIS 40-50, remifentanil 2 ng ml−1; Group 3: BIS 40-50, remifentanil 4 ng ml−1; Group 4: BIS 25-35, remifentanil 2 ng ml−1; Group 5: BIS 55-65, remifentanil 2 ng ml−1]. A 60 mA tetanic stimulus was applied for 5 s on the ulnar nerve. From the digitized pulse oximeter wave recorded on a laptop computer, linear and non-linear parameters of PPG variation during the 60 s period after stimulation were computed. The haemodynamic response to subsequent orotracheal intubation was recorded. The PPG variation was compared between groups and between responders and non-responders to intubation (anova). Variables independently predicting the response were determined by logistic regression. Results. The probability of a response to tracheal intubation was 0.77, 0.47, 0.05, 0.18 and 0.52 in Groups 1-5, respectively (P<0.03). The PPG variability was significantly higher in responders than in non-responders but it did not improve the prediction of the response to tracheal intubation based on BIS level and effect site remifentanil concentration. Conclusion. Tetanic stimulation induced PPG variation does not reflect the analgesic state in a wide clinical range of surgical anaesthesi
Theory and practice of trauma-focused mentalization-based treatment: Is trauma treatment possible in a group setting?
Currently, there are no official treatment guidelines for complex posttraumatic stress disorder (cPTSD). The cPTSD differs from PTSD in the symptoms, duration or frequency of trauma exposure and in a high comorbidity with borderline personality disorder (BPD). Thus, there is a need for the development of new treatment methods targeted for this patient population. This article presents a new trauma-focused mentalization-based treatment using a group treatment approach that was developed for patients with cPTSD. In addition to the theoretical background and the conceptual framework of trauma in mentalization-based treatment, the treatment procedure is described in detail and illustrated based on a case example
Heart rate variability does not discriminate between different levels of haemodynamic responsiveness during surgical anaesthesia†
Background Hypnotic depth but not haemodynamic responsiveness is measured with EEG-based monitors. In this study we compared heart rate variability (HRV) in unstimulated patients and stimulation-induced HRV at different levels of anaesthesia. Methods A total of 95 ASA I or II patients were randomly assigned to five groups (Group 1: BIS 45(5), remifentanil 1 ng ml−1; Group 2: BIS 45(5), remifentanil 2 ng ml−1; Group 3: BIS 45(5), remifentanil 4 ng ml−1; Group 4: BIS 30(5), remifentanil 2 ng ml−1; Group 5: BIS 60(5), remifentanil 2 ng ml−1). A time- and frequency-domain analysis of the RR interval (RRI) from the electrocardiogram was performed. HRV before induction, before and after a 5 s tetanic stimulus of the ulnar nerve, and before and after tracheal intubation was compared between groups, between stimuli, and between responders to intubation [systolic arterial pressure (SAP) increase >20 mm Hg, a maximal heart rate (HR) after intubation >90 min−1 or both] and non-responders (anova). Results Induction of anaesthesia significantly lowered HR and HRV. Mean RRI before stimulation was higher in G3 than in G1, G2, and G4 (P < 0.001), whereas the other HRV parameters were similar. Intubation induced a greater HRV response than tetanic stimulation. The mean RRI after intubation was lower in G3 compared with the other groups and the sd of the RRI after tetanic stimulation was lower in G3 compared with G5. Otherwise, unstimulated HRV and stimulation-induced HRV were similar in responders and non-responders. Conclusion HRV parameters discriminate between awake and general anaesthesia, are different after tracheal intubation and a 5 s ulnar nerve stimulation, but do not discriminate between different levels of haemodynamic responsiveness during surgical anaesthesi
CT angiography, MR angiography and rotational digital subtraction angiography for volumetric assessment of intracranial aneurysms. An experimental study
The purpose of our experimental study was to assess the accuracy and precision of CT angiography (CTA), MR angiography (MRA) and rotational digital subtraction angiography (DSA) for measuring the volume of an in vitro aneurysm model. A rigid model of the anterior cerebral circulation harbouring an anterior communicating aneurysm was connected to a pulsatile circuit. It was studied using unenhanced 3D time-of-flight MRA, contrast-enhanced CTA and rotational DSA angiography. The source images were then postprocessed on dedicated workstations to calculate the volume of the aneurysm. CTA was more accurate than MRA (P=0.0019). Rotational DSA was more accurate than CTA, although the difference did not reach statistical significance (P=0.1605), and significantly more accurate than MRA (P<0.00001). CTA was more precise than MRA (P=0.12), although this did not reach statistical significance. Rotational DSA can be part of the diagnosis, treatment planning and support endovascular treatment of intracranial aneurysms. The emerging endovascular treatment techniques which consist of using liquid polymers as implants to exclude aneurysms from arterial circulation would certainly benefit from this precise measurement of the volume of aneurysm
Growth of Single Unit-Cell Superconducting LaSrCuO Films
We have developed an approach to grow high quality ultrathin films of
LaSrCuO with molecular beam epitaxy, by adding a
homoepitaxial buffer layer in order to minimize the degradation of the film
structure at the interface. The advantage of this method is to enable a further
reduction of the minimal thickness of a superconducting
LaSrCuO film. The main result of our work is that a
single unit cell (only two copper oxide planes) grown on a SrLaAlO
substrate exhibits a superconducting transition at 12.5 K (zero resistance) and
an in-plane magnetic penetration depth = 535 nm.Comment: to be published in "Solid State Electonics" special issue, conference
proceedings of the 9th Workshop on Oxide Electronics, St-Pete Beach, FL,
20-23 november 2002 : 12 pages 4 figures in preprint versio
Radiation dose in vertebroplasty
We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256mGy outside and 0.01-0.47mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurement
WIRA-C: a compact 142-GHz-radiometer for continuous middle-atmospheric wind measurements
Ground-based microwave wind radiometry provides a method to measure
horizontal wind speeds at altitudes between 35 and 75 km as has been shown
by various previous studies. No other method is capable of continuously
delivering wind measurements in this altitude region. As opposed to lidar
systems, microwave radiometers operate autonomously and independent of
daylight and clouds.In this paper, we present the WIRA-C (Wind Radiometer for Campaigns)
instrument that observes the 142.17504 GHz rotational transition line of
ozone with a high spectral resolution using a low noise single side band
heterodyne receiver. Because the emitting molecules are drifting with the
wind, the line is Doppler shifted. Together with the pressure broadening
effect, this allows the retrieval of altitude resolved wind profiles.The novel WIRA-C instrument represents the newest development in microwave
wind radiometry and implements many improvements over its predecessor, the
WIRA instrument. The main improvements include the compact structure, lower
noise and an advanced retrieval setup. This paper describes the instrument
and the data processing with a focus on the retrieval that takes into account
a three-dimensional atmosphere and has never been used in ground-based
radiometry before. The retrieval yields profiles of horizontal wind speeds
with a 12 h time resolution and a vertical resolution of 10 km for zonal
and 10 to 15 km for meridional wind speeds. We give an error estimate that
accounts for the thermal noise on the measured spectra and additionally
estimate systematic errors using Monte Carlo methods.WIRA-C has been continuously measuring horizontal wind speeds for 1 year
at the Maïdo observatory on Réunion (21.4° S,
55.9° E). We present the time series of this campaign and compare
our measurements to model data from the European Centre for Medium-range
Weather Forecasts (ECMWF) and coincident measurements of the co-located
Rayleigh–Mie Doppler wind lidar. We find a good agreement between our
measurements and the ECMWF operational analysis for the time series, where
many features are present in both datasets. The wind profiles of the
coincident WIRA-C and lidar observations are consistent and agree within
their respective uncertainties for the lidar measurements with long
integration times.</p
ADC mapping of the aging frontal lobes in mild cognitive impairment
Normal aging, leukoaraiosis (LA) and vascular disease particularly involve the human frontal lobes. We decided to investigate a population of elderly patients referred for neuroimaging because of progressive minor cognitive deficits but no dementia. They underwent conventional Magnetic resonance imaging (MRI) using axial T1 and T2-weighted imaging as well as coronal FLAIR sequences in addition to the axial diffusion-weighted MRI. MRI allowed us to differentiate patients with leukoaraïosis (LA+) from those without it (LA-) and mapping of the apparent diffusion coefficient (ADC) to investigate local tissular water motion.We observed an increase in the ADC in all investigated patients with increasing age (r=0.326, p=0.002). This increase was observed in both patients groups (LA+ and LA-) . In addition, the LA+ group had significant higher ADC values than the LA- group after controlling for age (p<0.0001
MLPH Genotype—Melanin Phenotype Correlation in Dilute Dogs
Coat color dilution in dogs is a specific pigmentation phenotype caused by a defective transport of melanosomes leading to large clumps of pigment. It is inherited as a Mendelian autosomal recessive trait and may be accompanied by hair loss, the so-called color dilution alopecia (CDA), or black hair follicular dysplasia (BHFD). We previously identified the noncoding c.-22G>A transition in the melanophilin gene (MLPH) as a candidate causative mutation for the dilute phenotype. We have now extended our study and genotyped 935 dogs from 20 breeds segregating for dilute coat color. The dilute-associated A allele segregates in many different breeds suggesting an old mutation event. We also investigated skin biopsies of dogs suspected of having either CDA or BHFD, and our data clearly indicate that the dilute mutation is required but not sufficient to develop clinical signs of the disease. The risk to develop CDA/BHFD seems to be breed specific. Interestingly, 22 out of 29 dogs with clinical signs of CDA/BHFD have clumped melanin in the epidermis, the follicular epithelium, and the hair shafts, whereas in dilute dogs without clinical disease, clumped melanin is only found in the follicular epithelium and the hair shafts but not in the epidermi
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