21 research outputs found
Strain gradient induced polarization in SrTiO3 single crystals
Piezoelectricity is inherent only in noncentrosymmetric materials, but a
piezoelectric response can also be obtained in centrosymmetric crystals if
subjected to inhomogeneous deformation. This phenomenon, known as
flexoelectricity, affects the functional properties of insulators, particularly
thin films of high permittivity materials. We have measured
strain-gradient-induced polarization in single crystals of paraelectric
SrTiO as a function of temperature and orientation down to and below the
105 K phase transition. Estimates were obtained for all the components of the
flexoelectric tensor, and calculations based on these indicate that local
polarization around defects in SrTiO may exceed the largest ferroelectric
polarizations. A sign reversal of the flexoelectric response detected below the
phase transition suggests that the ferroelastic domain walls of SrTiO may
be polar.Comment: 4 pages, 3 figures, 1 tabl
Path integral Monte Carlo simulations of silicates
We investigate the thermal expansion of crystalline SiO in the --
cristobalite and the -quartz structure with path integral Monte Carlo
(PIMC) techniques. This simulation method allows to treat low-temperature
quantum effects properly. At temperatures below the Debye temperature, thermal
properties obtained with PIMC agree better with experimental results than those
obtained with classical Monte Carlo methods.Comment: 27 pages, 10 figures, Phys. Rev. B (in press
A combined X-ray scattering and simulation study of halothane in membranes at raised pressures
Using a combination of high pressure wide angle X-ray scattering experiments and molecular dynamics simulations, we probe the effect of the archetypal general anaesthetic halothane on the lipid hydrocarbon chain packing and ordering in model bilayers and the variation in these parameters with pressure. Incorporation of halothane into the membrane causes an expansion of the lipid hydrocarbon chain packing at all pressures. The effect of halothane incorporation on the hydrocarbon chain order parameter is significantly reduced at elevated pressure
Isoflurane does not aggregate inside POPC bilayers at high pressure: Implications for pressure reversal of general anaesthesia
International audienceWe placed isoflurane, a general anaesthetic, inside palmitoyloleoylphosphatidylcholine (POPC) bilay-ers at clinical concentration, and performed molecular dynamics simulations at atmospheric and raised pressures, using two different thermodynamic ensembles. We also performed a simulation of this system with isoflurane at ten times the clinical concentration. We found that isoflurane did not aggregate inside POPC membranes at 20 MPa, nor at 40 MPa. The implications of these findings for pressure reversal is discussed, in light of the high-pressure neurological syndrome
A combined X-ray scattering and simulation study of halothane in membranes at raised pressures
a b s t r a c t Using a combination of high pressure wide angle X-ray scattering experiments and molecular dynamics simulations, we probe the effect of the archetypal general anaesthetic halothane on the lipid hydrocarbon chain packing and ordering in model bilayers and the variation in these parameters with pressure. Incorporation of halothane into the membrane causes an expansion of the lipid hydrocarbon chain packing at all pressures. The effect of halothane incorporation on the hydrocarbon chain order parameter is significantly reduced at elevated pressure
Dasher
Dasher is an information-efficient text-entry interface, which can be driven by natural continuous pointing gestures or by pressing buttons. Dasher is a competitive text-entry system wherever a full-size keyboard cannot be used - for example, when operating a computer one-handed, by joystick, touchscreen, trackball, or mouse; when operating a computer with zero hands (i.e., by head-mouse or by eyetracker); on a palmtop computer; on a wearable computer. The gazetracking version of Dasher allows an experienced user to write text as fast as normal handwriting - 29 words per minute; using a mouse, experienced users can write at 39 words per minute. Dasher can be used to write efficiently in any language. Dasher is free software (distributed under the GPL) and is available for many computer platforms, including linux, windows, and android
Trimodality therapy for malignant pleural mesothelioma: Results from an EORTC phase II multicentre trial
The European Organisation for Research and Treatment of Cancer (EORTC; protocol 08031) phase II trial investigated the feasibility of trimodality therapy consisting of induction chemotherapy followed by extrapleural pneumonectomy and post-operative radiotherapy in patients with malignant pleural mesothelioma (with a severity of cT3N1M0 or less). Induction chemotherapy consisted of three courses of cisplatin 75 mg·m -2 and pemetrexed 500 mg·m -2. Nonprogressing patients underwent extrapleural pneumonectomy followed by postoperative radiotherapy (54 Gy, 30 fractions). Our primary end-point was "success of treatment" and our secondary end-points were toxicity, and overall and progression-free survival. 59 patients were registered, one of whom was ineligible. Subjects' median age was 57 yrs. The subjects' TNM scores were as follows: cT1, T2 and T3, 36, 16 and six patients, respectively; cN0 and N1, 57 and one patient, respectively. 55 (93%) patients received three cycles of chemotherapy with only mild toxicity. 46 (79%) patients received surgery and 42 (74%) had extrapleural pneumonectomy with a 90-day mortality of 6.5%. Post-operative radiotherapy was completed in 37 (65%) patients. Grade 3-4 toxicity persisted after 90 days in three (5.3%) patients. Median overall survival time was 18.4 months (95% CI 15.6-32.9) and median progression-free survival was 13.9 months (95% CI 10.9-17.2). Only 24 (42%) patients met the definition of success (one-sided 90% CI 0.36-1.00). Although feasible, trimodality therapy in patients with mesothelioma was not completed within the strictly defined timelines of this protocol and adjustments are necessary. Copyrigh