Twin-free YBa2Cu3O7 films on (001) NdGaO3 showing isotropic electrical behaviour

Investigating the epitaxial nature of YBa2Cu3O7 films on NdGaO3 (001) by Rutherford backscattering (RBS) and X-ray diffraction (XRD) texture measurements we find that the films are almost single crystalline, in the sense that the a, b and c axes are uniquely defined with respect to those of NdGaO3. The crystalline perfection is, however, not reflected in the electrical properties of the films. Although we measure a Tc of 89.7 K, we did not observe the expected anisotropy in the resistivity. We interpret this to be due to Ga diffusion from the substrate into the film, which effectively blocks the chain conductivity

A Biomechanical Model for the Development of Myoelectric Hand Prosthesis Control Systems

Advanced myoelectric hand prostheses aim to reproduce as much of the human hand's functionality as possible. Development of the control system of such a prosthesis is strongly connected to its mechanical design; the control system requires accurate information on the prosthesis' structure and the surrounding environment, which can make development difficult without a finalized mechanical prototype. This paper presents a new framework for the development of electromyographic hand control systems, consisting of a prosthesis model based on the biomechanical structure of the human hand. The model's dynamic structure uses an ellipsoidal representation of the phalanges. Other features include underactuation in the fingers and thumb modeled with bond graphs, and a viscoelastic contact model. The model's functions are demonstrated by the execution of lateral and tripod grasps, and evaluated with regard to joint dynamics and applied forces. Finally, additions are suggested with which this model can be of use in mechanical design and patient training as well

Mechanical design and control of a new myoelectric hand prosthesis

The development of modern, myoelectrically controlled hand prostheses can be difficult, due to the many requirements its mechanical design and control system need to fulfill [1]. The hand should be controllable with few input signals, while being able to perform a wide range of motions. It should be lightweight and slim, but be able to actuate all fingers separately. To accomplish this, new control and mechanical design techniques are implemented in a modern hand prosthesis prototype

The ab-anisotrophy of twinfree YBa₂Cu₃O_7-δ films above and below T_c

High quality twin-free c-axis oriented YBa2Cu3O7 films were grown by pulsed laser deposition on NdGaO3. We find resistive anisotropies between 1 < a/b < 1.6. The resistive anisotropy above Tc appears to be correlated to the anisotropy in the critical current below Tc. The normal state properties of the chains along b seem to have a significant influence on the superconducting properties of YBa2Cu3O7

A biomechanical model for the development of myoelectric hand prosthesis control systems

Advanced myoelectric hand prostheses aim to reproduce as much of the human hand's functionality as possible. Development of the control system of such a prosthesis is strongly connected to its mechanical design; the control system requires accurate information on the prosthesis' structure and the surrounding environment, which can make development difficult without a finalized mechanical prototype. This paper presents a new framework for the development of electromyographic hand control systems, consisting of a prosthesis model based on the biomechanical structure of the human hand. The model's dynamic structure uses an ellipsoidal representation of the phalanges. Other features include underactuation in the fingers and thumb modeled with bond graphs, and a viscoelastic contact model. The model's functions are demonstrated by the execution of lateral and tripod grasps, and evaluated with regard to joint dynamics and applied forces. Finally, additions are suggested with which this model can be of use in mechanical design and patient training as well

Brain computer tomography in critically ill patients -- a prospective cohort study

<p>Abstract</p> <p>Background</p> <p>Brain computer tomography (brain CT) is an important imaging tool in patients with intracranial disorders. In ICU patients, a brain CT implies an intrahospital transport which has inherent risks. The proceeds and consequences of a brain CT in a critically ill patient should outweigh these risks. The aim of this study was to critically evaluate the diagnostic and therapeutic yield of brain CT in ICU patients.</p> <p>Methods</p> <p>In a prospective observational study data were collected during one year on the reasons to request a brain CT, expected abnormalities, abnormalities found by the radiologist and consequences for treatment. An “expected abnormality” was any finding that had been predicted by the physician requesting the brain CT. A brain CT was “diagnostically positive”, if the abnormality found was new or if an already known abnormality was increased. It was “diagnostically negative” if an already known abnormality was unchanged or if an expected abnormality was not found. The treatment consequences of the brain CT, were registered as “treatment as planned”, “treatment changed, not as planned”, “treatment unchanged”.</p> <p>Results</p> <p>Data of 225 brain CT in 175 patients were analyzed. In 115 (51%) brain CT the abnormalities found were new or increased known abnormalities. 115 (51%) brain CT were found to be diagnostically positive. In the medical group 29 (39%) of brain CT were positive, in the surgical group 86 (57%), <it>p</it> 0.01. After a positive brain CT, in which the expected abnormalities were found, treatment was changed as planned in 33%, and in 19% treatment was changed otherwise than planned.</p> <p>Conclusions</p> <p>The results of this study show that the diagnostic and therapeutic yield of brain CT in critically ill patients is moderate. The development of guidelines regarding the decision rules for performing a brain CT in ICU patients is needed.</p

Long-term disease burden and survivorship issues after surgery and radiotherapy of intracranial meningioma patients

BACKGROUND Many intracranial meningioma patients have an impaired health-related quality of life (HRQoL) and neurocognitive functioning up to 4 yr after intervention. OBJECTIVE To assess the long-term (≥5 yr) disease burden of meningioma patients. METHODS In this multicenter cross-sectional study, patients ≥5 yr after intervention (including active magnetic resonance imaging (MRI) surveillance) were included and assessed for HRQoL (Short-Form Health Survey 36), neurocognitive functioning (neuropsychological assessment), anxiety and depression (Hospital Anxiety and Depression Scale), and work productivity (Short Form-Health and Labour Questionnaire). Multivariable and propensity score regression analyses were used to compare patients and controls, and different treatment strategies corrected for possible confounders. Clinically relevant differences were reported. RESULTS At a median of 9 yr follow-up after intervention, meningioma patients (n = 190) reported more limitations due to physical (difference 12.5 points, P = .008) and emotional (13.3 points, P = .002) health problems compared with controls. Patients also had an increased risk to suffer from anxiety (odds ratio [OR]: 2.6, 95% CI: 1.2-5.7) and depression (OR: 3.7, 95% CI: 1.3-10.5). Neurocognitive deficits were found in 43% of patients. Although postoperative complications, radiotherapy, and reresection were associated with worse verbal memory, attention, and executive functioning when compared to patients resected once, the only clinically relevant association was between reresection and worse attention (–2.11, 95% CI: –3.52 to –0.07). Patients of working age less often had a paid job (48%) compared with the working-age Dutch population (72%) and reported more obstacles at work compared with controls. CONCLUSION In the long term, a large proportion of meningioma patients have impaired HRQoL, neurocognitive deficits, and high levels of anxiety or depression. Patients treated with 1 resection have the best neurocognitive functioning

Analyses of cerebral microdialysis in patients with traumatic brain injury: relations to intracranial pressure, cerebral perfusion pressure and catheter placement

<p>Abstract</p> <p>Background</p> <p>Cerebral microdialysis (MD) is used to monitor local brain chemistry of patients with traumatic brain injury (TBI). Despite an extensive literature on cerebral MD in the clinical setting, it remains unclear how individual levels of real-time MD data are to be interpreted. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) are important continuous brain monitors in neurointensive care. They are used as surrogate monitors of cerebral blood flow and have an established relation to outcome. The purpose of this study was to investigate the relations between MD parameters and ICP and/or CPP in patients with TBI.</p> <p>Methods</p> <p>Cerebral MD, ICP and CPP were monitored in 90 patients with TBI. Data were extensively analyzed, using over 7,350 samples of complete (hourly) MD data sets (glucose, lactate, pyruvate and glycerol) to seek representations of ICP, CPP and MD that were best correlated. MD catheter positions were located on computed tomography scans as pericontusional or nonpericontusional. MD markers were analyzed for correlations to ICP and CPP using time series regression analysis, mixed effects models and nonlinear (artificial neural networks) computer-based pattern recognition methods.</p> <p>Results</p> <p>Despite much data indicating highly perturbed metabolism, MD shows weak correlations to ICP and CPP. In contrast, the autocorrelation of MD is high for all markers, even at up to 30 future hours. Consequently, subject identity alone explains 52% to 75% of MD marker variance. This indicates that the dominant metabolic processes monitored with MD are long-term, spanning days or longer. In comparison, short-term (differenced or Δ) changes of MD vs. CPP are significantly correlated in pericontusional locations, but with less than 1% explained variance. Moreover, CPP and ICP were significantly related to outcome based on Glasgow Outcome Scale scores, while no significant relations were found between outcome and MD.</p> <p>Conclusions</p> <p>The multitude of highly perturbed local chemistry seen with MD in patients with TBI predominately represents long-term metabolic patterns and is weakly correlated to ICP and CPP. This suggests that disturbances other than pressure and/or flow have a dominant influence on MD levels in patients with TBI.</p