Synthesis of 2,7‐Carbazolenevinylene‐Based Copolymers and Characterization of Their Photovoltaic Properties

New electroactive and photoactive conjugated copolymers consisting of alternating 2,7‐carbazole and oligothiophene moieties linked by vinylene groups have been developed. Different oligothiophene units have been introduced to study the relationship between the polymer structure and the electronic properties. The resulting copolymers are characterized by UV‐vis spectroscopy, size‐exclusion chromatography, and thermal and electrochemical analyses. Bulk heterojunction photovoltaic cells from different copolymers and a soluble fullerene derivative, [6,6]‐phenyl‐C₆₁ butyric acid methyl ester, have been fabricated, and promising preliminary results are obtained. For instance, non‐optimized devices using poly(N‐(4‐octyloxyphenyl)‐2,7‐carbazolenevinylene‐alt‐3″,4″‐dihexyl‐2,2′;5′,2″;5″,2″′;5″′,2″″‐quinquethiophenevinylene 1″,1″‐dioxide) as an absorbing and hole‐carrier semiconductor exhibit power conversion efficiency up to 0.8 % under air mass (AM) 1.5 illumination. These features make 2,7‐carbazolenevinylene‐based and related polymers attractive candidates for solar‐cell applications.     

Analysis of electrocardiograms during atrial fibrillation

The research discussed in this article is motivated by the search for an optimal classification of the different types of atrial fibrillation (AF) on the basis of recorded atrial signals. This would facilitate the selection of an optimal therapy. This article focuses on the biophysical models of the genesis of ECG waveforms during AF. The model of the electric activity of the atria was found to have sufficient realism to be used to describe the electric sources during AF. The inclusion of the volume conduction model resulted in electrocardiographic signals that are in all aspects similar to those observed clinically. The model is currently applied to solve various problems related to optimal signal preprocessing and extraction of features in AF signals for the classification of AF abnormalities. The biophysical model of the atrial activity is an essential element in this research, since it is capable of describing the electric source specifications derived from different hypotheses relating to the etiology of AF     

Associative retuning in the thalamic source of input to the amygdala and auditory cortex: Receptive field plasticity in the medial division of the medial geniculate body.

The medial division of the medial geniculate body (MGm) projects to the lateral amygdala and the upper layer of the auditory cortex and develops physiological plasticity rapidly during classical conditioning. The effects of learning on frequency receptive fields (RFs) in the MGm of the guinea pig have been determined. Classical conditioning (tone–footshock), as indexed by rapid development of conditioned bradycardia, produced conditioned stimulus (CS)–frequency specific RF plasticity: increased response at the CS frequency with decreased responses at other frequencies, both immediately and after a 1-hr retention period. Sensitization training produced only general changes in RFs. These findings are considered with reference to both the elicitation of amygdala-mediated, fear-conditioned responses and the mechanism of retrieval of information stored in the auditory cortex during acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical trial of retrograde warm blood reperfusion versus standard cold topical irrigation of transplanted hearts

BACKGROUND: A prospective, randomized clinical study involving 34 patients undergoing heart transplantation compared myocardial preservation of donor hearts maintained with continuous reperfusion with retrograde warm blood cardioplegia during surgical implantation versus the standard cold topical irrigation. METHODS: Hearts in both groups were arrested with a standard crystalloid solution and maintained in a cold saline solution during transportation. In the retrograde group, cardioplegia was administered through a catheter in the coronary sinus during surgical implantation. An average of 471 +/- 30 mL of hyperkalemic crystalloid solution diluted 1:4 in warm blood from the oxygenator was infused. In the standard group, the heart was kept cold by topical irrigation of cold saline solution and was reperfused only when the ascending aorta was unclamped. RESULTS: Preoperative characteristics of donors and recipients were similar in the two cohorts. Ischemic time average 139 +/- 12 minutes in the retrograde group compared with 130 +/- 11 minutes in the standard group (p = 0.57). Cardiopulmonary bypass time averaged 89 +/- 4 minutes in the retrograde group and 110 +/- 12 minutes in the standard group (p = 0.12). Defibrillation at reperfusion was performed in 4 patients (4/17, 24%) in the retrograde group and 12 patients (12/18, 67%) in the standard group (p = 0.01). There were no deaths in the retrograde group (0/17), whereas in the standard group, 3 patients (3/17) died of early graft failure (p = 0.11). Four early graft failures occurred in the standard group (p = 0.06). Two patients (2/17, 12%) were weaned from bypass with ventricular assist devices in the standard group. The number of subendocardial necrotic cells in the first two weekly endomyocardial biopsy specimens averaged 2.7 +/- 0.8 cells/mm2 in the retrograde group and 5.9 +/- 2.4 cells/mm2 in the standard group (p = 0.12). CONCLUSIONS: Retrograde warm blood reperfusion appears to improve the initial recovery of transplanted hearts. The technique is easy to use and may be a useful approach to graft protection during surgical implantation.     

Performance analysis of a COFDM/FM in-band digital audiobroadcasting system

In this paper, we present a performance analysis of a coded orthogonal frequency division multiplexing DAB system that is power multiplexed over a commercial FM station. We model the mobile channel with a time-frequency scattering function. Results show that the performance of the FM demodulator is crucial, since the level of the residual FM signal has a strong influence on the BER performance of the COFDM system. As with other mobile communication systems, the use of interleaving greatly enhances the performances     

Monitoring non-carbonated (‘still’) mineral waters for aerobic colonization

Fifty samples each of two leading brands of French, non-carbonated (‘still’) mineral waters, packed in plastic bottles, were stored in the dark for one month at approximately 20°C to allow marked proliferation of their autotrophic microbial flora. Upon completion of this challenge test 1250 ml per bottle were filtered through five membranes, which were subsequently cultured on 1/10 strength nutrient agar for 48 h at a temperature favouring the growth of thermotrophic organisms only, i.e. 42 ± 0.5°C. The numbers of colonies per one litre were below 10³ in all samples and did not exceed 200 in 56–80%, depending on the brand. Identification of the isolates demonstrated strong inhibition of the psychrotrophic. Gram-negative types, predominating in the association flora of stored still waters and preponderance of Gram-positive, catalase-positive, facultatively anaerobic cocci. Consequently, a Reference Value for the thermotrophic autotrophic colony count per 1 ml in still, commercial mineral waters of the order m = 1 and M = 5 seems justified. It is emphasized that, besides examining for these trivial organism, the usual tests for marker bacteria (Escherichia coli and Lancefield group D streptococci) and Pseudomonas aeruginosa should always be carried out.     

The local structure of image discontinuities in one dimension

The detailed structure of intensities in the local neighborhood of an edge can often indicate the nature of the physical event givinig rise to that edge. We argue that the limit, as we approach arbitrarily close to either side of an edge, of such image parameters as type of texture, texture gradient, color, appropriate directional derivatives of intensity, etc., is a key aspect of this structure. However, the general problem of capturing this local structure is surprisingly complex. Thus, we restrict ourselves in this paper to a relatively simple domain?one-dimensional cuts through idealized images modeled by piecewise smooth (C1) functions corrupted by Gaussian noise. Within this domain, we define local structure to be the limit of the uncorrupted intensity and of its derivatives as we approach arbitrarily close to either side of a discontinuity. We develop a technique that captures this local structure while simultaneously locating the discontinuities, and demonstrate that these tasks are in fact inseparable. The technique is an extension, using estimation theory, of the classical definition of discontinuity. It handles, in a consistent fashion, both jump discontinuities in the function and jump discontinuities in its first derivative (so-called step-edges are a special case of the former and roof-edges of the latter). It also integrates, again in a consistent fashion, information derived from a number of different neighborhood sizes.     

Coupling of polystyrene to a silane-treated mica

This paper deals with the coupling of polystyrene to a closely packed and highly ordered cationic vinylbenzyl silane (CVBS) on mica. It is shown that a thermal treatment is required for maximum retention of polystyrene on treated mica. Moreover, a thermal treatment at 250°C is much more effective than one at 170°C. The effect of the number of silane monolayers on mica was investigated. In general, one monolayer of CVBS gave optimum retention of polystyrene. The addition of peroxides further improved this retention and at the same time allowed the use of lower treatment temperatures. Some data are presented which consider the importance of the silane solution concentration and silane functional groups.