Sites of alcohol and volatile anaesthetic action on GABA(A) and glycine receptors

Volatile anaesthetics have historically been considered to act in a nonspecific manner on the central nervous system. More recent studies, however, have revealed that the receptors for inhibitory neurotransmitters such as gamma-aminobutyric acid (GABA) and glycine are sensitive to clinically relevant concentrations of inhaled anaesthetics. The function of GABA(A) and glycine receptors is enhanced by a number of anaesthetics and alcohols, whereas activity of the related GABA rho1 receptor is reduced. We have used this difference in pharmacology to investigate the molecular basis for modulation of these receptors by anaesthetics and alcohols. By using chimaeric receptor constructs, we have identified a region of 45 amino-acid residues that is both necessary and sufficient for the enhancement of receptor function. Within this region, two specific amino-acid residues in transmembrane domains 2 and 3 are critical for allosteric modulation of both GABA(A) and glycine receptors by alcohols and two volatile anaesthetics. These observations support the idea that anaesthetics exert a specific effect on these ion-channel proteins, and allow for the future testing of specific hypotheses of the action of anaesthetics.     

The anti-reflective algebra: structural and computational analysis with application to image deblurring and denoising

Anti-reflective (AR) boundary conditions (BC) have been introduced recently in connection with fast deblurring algorithms, both in the case of signals and images. Here we extend such BCs to d dimensions (d ≥ 1) and we study in detail the algebra induced by the AR-BCs, with strongly symmetric point spread functions (PSF), both from a structural and computational point of view. The use of the re-blurring idea and the computational features of the AR-algebra allow us to apply Tikhonov-like techniques within O(n ^d log(n)) arithmetic operations, where n ^d is the number of pixels of the reconstructed object. Extensive numerical experimentation concerning 2D images and strongly symmetric PSFs confirms the effectiveness of our proposal.      

Numerical solution of the nonlinear Schrödinger equation,starting from the scattering data

Starting from the scattering data, the initial-value problem for the focusing nonlinear Schrödinger equation is solved numerically by following the path of the inverse scattering transform. The numerical results of an extensive experimentation suggest that: (a) our method is very effective, whenever the scattering data are analytically known; (b) the split-step Fourier method is not really effective if the exact solution is not smooth enough.     

A covert attention P300-based brain-computer interface: Geospell

The Farwell and Donchin P300 speller interface is one of the most widely used brain-computer interface (BCI) paradigms for writing text. Recent studies have shown that the recognition accuracy of the P300 speller decreases significantly when eye movement is impaired. This report introduces the GeoSpell interface (Geometric Speller), which implements a stimulation framework for a P300-based BCI that has been optimised for operation in covert visual attention. We compared the Geospell with the P300 speller interface under overt attention conditions with regard to effectiveness, efficiency and user satisfaction. Ten healthy subjects participated in the study. The performance of the GeoSpell interface in covert attention was comparable with that of the P300 speller in overt attention. As expected, the effectiveness of the spelling decreased with the new interface in covert attention. The NASA task load index (TLX) for workload assessment did not differ significantly between the two modalities. PRACTITIONER SUMMARY: This study introduces and evaluates a gaze-independent, P300-based brain-computer interface, the efficacy and user satisfaction of which were comparable with those off the classical P300 speller. Despite a decrease in effectiveness due to the use of covert attention, the performance of the GeoSpell far exceeded the threshold of accuracy with regard to effective spelling.     

Characterization of the interaction layer in diffusion couples U-7 wt.%Mo/Al 6061 alloy at 550 °C and 340 °C.: Effect of the γU(Mo) cellular decomposition

Solid state reaction between U-7 wt.%Mo and Al 6061 alloys at 550 °C and 340 °C was characterized in chemical diffusion couples made by Friction Stir Welding. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. At 550 °C the interaction layer in γU(Mo)/Al 6061 is formed by U(Al,Si)₃ phase but when γU(Mo) cellular decomposition occurs, UAl₃ and Al₄₃Mo₄U₆ also appear in the interaction layer. At 340 °C the use of X-ray diffraction with synchrotron radiation made it possible to analyze the interaction layer. It was found that it is only formed by U₃Si₅ phase with its cell volume enlarged respect to the original one.     

Controlled Nucleation of GaN Nanowires Grown with Molecular Beam Epitaxy

The location of GaN nanowires is controlled with essentially perfect selectivity using patterned SiN_x prior to molecular beam epitaxy growth. Nanowire growth is uniform within mask openings and absent on the mask surface for over 95% of the usable area of a 76 mm diameter substrate. The diameters of the resulting nanowires are controlled by the size of the mask openings. Openings of approximately 500 nm or less produce single nanowires with symmetrically faceted tips.     

The Formation of Oxalic Acid During Bleaching of Kraft Pulp

Abstract

Calcium oxalate scaling is a major practical problem in a paper mill, especially in the evaporators, pulp digesters, and the bleach room. The sources of oxalic acid were determined by analysis of mill samples. In the unbleached pulp mill, the source of oxalic acid is the wood. In addition, a major amount of oxalic acid was found to be formed in the bleach room. A laboratory bleaching study was undertaken to establish a quantitative relationship betweeen bleaching conditions and oxalic acid production. Hardwood kraft pulp was bleached using three sequences. The amount of oxalic acid produced was dependent upon the available lignin content of the pulp (Kappa number) and not the oxidant concentration or reaction temperature.     

A.c.-impedance spectroscopy study of oxygen reduction at Nafion® coated gas-diffusion electrodes in sulphuric acid: Teflon loading and methanol cross-over effects

The kinetics of oxygen reduction have been studied at Nafion®-coated dual layer gas-diffusion electrodes at 60 °C in 2.5 M H₂SO₄. A.c. impedance and steady state galvanostatic measurements have been carried out on electrodes containing various PTFE loadings. A.c. impedance spectroscopy supplied information on charge transfer resistance, series resistance and double layer capacitance of electrodes during the oxygen reduction process. These parameters, together with those derived by d.c. measurements (i.e. Tafel slopes, charge transfer coefficient, etc.), allowed a better identification of the features governing the electrode efficiency and the reduction mechanism. The best electrode was found to be one containing 30% PTFE; this showed both the lowest charge transfer resistance and the lowest overpotential for oxygen reduction. This electrode also showed lower overpotential than the same uncoated electrode at low current densities. The poisoning effect by methanol has been also investigated. Upon addition of methanol to the solution, no change was observed in the reaction mechanism at low overpotentials. In contrast, a significant variation of the Tafel slope was observed at high overpotentials. This behaviour is interpreted in terms of the variation of Pt-O bond strength as a function of electrode potential.     

Philadelphia chromosome-positive (Ph+) childhood acute lymphoblastic leukemia: good initial steroid response allows early prediction of a favorable treatment outcome

Among 4,760 acute lymphoblastic leukemia (ALL) patients enrolled from 1986 to 1995 in two subsequent trials of the BFM and AIEOP study group, 61 patients were found to have Philadelphia chromosome-positive (Ph+) ALL. These patients were analyzed for presenting features and treatment outcome to identify specific prognostic factors. Treatment stratification was based on initial cell mass and early response as determined by blast count in peripheral blood after a 7-day induction prephase with prednisone and one dose of intrathecal methotrexate on day 1. All patients were treated by similar intensive Berlin-Frankfurt-Münster (BFM) protocols. The median age of Ph+ patients was 7.5 years, the median white blood cell count (WBC) was 75 x 10(9)/L, 77% of patients had common ALL, and 29% coexpressed myeloid markers. After a median observation time of 4.2 years, 29 of 61 patients are alive (survival probability [pSUR] at 4 years, 0.49; standard error [SE], 0.06), and 24 of 61 are in first complete remission (CR1; probability of event-free survival [pEFS] at 4 years, 0.38; SE, 0.06). Twenty (35%) of 57 evaluable patients had >/=1,000 leukemic blasts per microliter of blood on day 8 of induction (defined as prednisone-poor-response [PPR]). These patients were older (10.0 v 6.88 years; P = .02) and had a higher WBC (144 v 29 x 10(9)/L; P = .0016) as compared with patients with prednisone good response (PGR; <1,000 blasts/microL at day 8). Only 2 of 20 patients (10%) with PPR remained in CR1 and alive: 6 patients with PPR did not survive after allogeneic bone marrow transplantation (BMT) due to recurring disease (n = 3) and toxicity (n = 3), and 12 nontransplanted patients died due to progression (n = 5) or relapse (n = 7). In contrast, 26 (70%) of the 37 patients with PGR are alive. Of 18 patients transplanted by allo-BMT, 1 relapsed (now in CR2) and 4 died after BMT. Among the 19 patients with PGR treated by chemotherapy alone, 8 remained in CR1 and 11 relapsed, of which 4 are in CR2 or CR3. The prednisone response emerged as the only independent prognostic factor for survival in Cox regression analysis. Thus, two thirds of Ph+ childhood ALL cases can be identified early by PGR, which, when treated with intensive BFM chemotherapy, with or without BMT, have a significantly lower risk of treatment failure. With a median continuous complete remission (CCR) time of 4.1 years, pEFS for PGR is 0.55 (SE, 0.08) compared with 0.10 (SE, 0.07) in patients with PPR (P = .0001). PGR is also an indicator for treatment responsiveness and durable second remission after relapse, which in turn may provide a second chance for BMT.