Macroscopic and crystallographic density of solid-state extruded polyethylene

Summary The influence of draw ratio on macroscopic and crystallographic density of polyethylene with different initial morphologies, has been investigated by solid-state extrusion. An initial drop followed by an increase in macroscopic density as a function of draw ratio has been observed. Since precision X-ray measurements of unit cell parameters showed no variation of crystallographic density, it was concluded that plastic deformation of polyethylene upon drawing proceeds with a decrease of the degree of crystallinity. This was confirmed by differential scanning calorimetry.     

Arthroscopic lysis in knee arthrofibrosis

OBJECTIVE: To compare the efficacy and toxicity of three patient-controlled analgesia (PCA) morphine regimens. DESIGN: A prospective, randomized, pilot study of three PCA morphine regimens: (1) 1 mg with 6-minute lockout (n = 10), (2) 2 mg with 12-minute lockout (n = 12), and (3) 2 mg with 20-minute lockout (n = 12). SETTING: Large teaching institution. PARTICIPANTS: Thirty-four patients undergoing cholecystectomy or hysterectomy. MAIN OUTCOME MEASURES: Pain scores (0 = no pain, 1 = mild pain, 2 = moderate pain, 3 = severe pain), sedation scores, analgesic consumption, and patient attempts (patient activation of PCA device) and injections (doses actually delivered) were evaluated using analysis of covariance. Distribution of pain and sedation scores and adverse effects were assessed using Fisher's exact test. RESULTS: Data on 24 patients were evaluable. Six patients withdrew for poor pain control (2 in group 1, 1 in group 2, and 3 in group 3). Three other patients withdrew because of adverse effects and 1 withdrew because of pump problems. Mean morphine consumption did not differ significantly among the groups. Distribution of pain and sedation scores and the number of patients with nausea were similar across treatment groups. The mean injection to attempt ratio was significantly smaller in group 3 (0.71 +/- 0.11) compared with groups 1 and 2 (0.9 +/- 0.06 and 0.83 +/- 0.09, respectively; p = 0.001). Adverse events occurred similarly among treatment groups. CONCLUSIONS: No significant differences in the efficacy or toxicity of the three morphine PCA regimens were identified.     

VRCTC-310--a novel compound of purified animal toxins separates antitumor efficacy from neurotoxicity

Two purified animal venom toxins, crotoxin and cardiotoxin, have been combined to produce a unique natural product (VRCTC-310) currently under investigation as an antitumor agent by the National Cancer Institute. In vitro, it has demonstrated cytotoxic disease specificity and a unique mechanism of action when submitted to COMPARE analysis. In vivo, tolerance was developed to the neurotoxic properties of crotoxin which allowed comparison of several schedules of fixed and escalating daily i.m. doses to mice bearing s.c. Lewis Lung carcinoma. An 83% inhibition of tumor growth was achieved using an escalating dose schedule starting at 1.8 mg/kg and reaching 6.3 mg/kg/day on day 20. Although some irritation around the sites of i.m. injection was noted, animal weight loss was negligible and there were no other signs of adverse toxicity. This natural product represents a new, membrane interactive anticancer agent which produces a unique spectrum of cytotoxicity in vitro and which has demonstrated interesting in vivo antitumor efficacy.     

Non-contact handling in microassembly: Acoustical levitation

Microassembly is currently of the utmost importance in industry. Nevertheless, the classical assembly processes are no longer usable for very small components, typically ranging from 10  m to 10 mm, since usually neglected surface forces disturb the handling task by inducing adhesion between the component and the gripper. A promising alternative to tackle surface forces consists in levitating the handled component. The various advantages of this contactless handling method are reviewed here and justify the choice of this approach. Consequently, the numerous physical principles suitable for contactless handling are briefly described together with their limitations. The evaluation shows that acoustic levitation is best fitted in the case of microassembly. A classification of literature applications is presented hereafter with special focus on acoustic levitation. Finally, the most common models of acoustical levitation are inspected in a general way. The described models come within the scope of non-linear acoustics.     

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     

A theoretical framework for gain scheduling

The weighted incremental norm approach was originally introduced as a natural framework for extending well‐known H_∞ linear control concepts into the nonlinear context. In this paper, we investigate the numerous links between this new approach and the classical gain‐scheduling technique. Although based on heuristic rules, gain‐scheduled control is probably the most widespread nonlinear technique. In this paper, we point out that the control objectives of the gain‐scheduled controller design can be expressed as the weighted incremental norm minimization of a nonlinear operator. The result interest is twofold: it first provides a rigorous mathematical formulation of the gain‐scheduling problem. Furthermore, existing gain‐scheduling techniques can be interpreted as approximate solutions to the weighted incremental norm minimization of a nonlinear operator. Copyright © 2003 John Wiley & Sons, Ltd.     

Richard Lester Solomon (1918–1995): Obituary.

Memorializes Richard Solomon, one of the major learning theorists of the 2nd half of the 20th century. Solomon was named the 1st James M. Skinner University Professor of Science in 1975, was elected to the National Academy of Sciences, and was awarded, among other honors, the Warren Medal for research by the Society of Experimental Psychologists, the American Psychological Association Distinguished Scientific Contribution Award, and the American Psychological Foundation's Award for Distinguished Teaching in Experimental Psychology. He conducted research on a broad array of topics such as word frequency and perceptual defense, children's estimation of the size of tokens, hoarding behaviors in rats, and personality ratings and sociometric patterns. His work made a major contribution to the exploration of Pavlovian conditioning. Other topics of research focused on in Solomon's laboratories included avoidance learning, learned helplessness, punishment, and the opponent-process theory of acquired motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Catalytic behaviour and surface properties of supported lanthana

This paper deals with the role of dispersed lanthana as an active phase in several catalytic reactions: CO hydrogenation, CO oxidation, and oxidative dimerization of methane.

Characterization of the prepared catalysts indicates that lanthana can be effectively dispersed on silica and on ceria. While in the case of silica-supported catalysts lanthana appears at the surface, leading to an almost full coverage for loadings higher than 40%, in the case of ceria-based systems, lanthana forms a solid solution with the support.

In all the reactions studied, the presence of lanthana can be related to significant changes in the catalytic properties of the bare supports. Thus, the selectivity towards the total oxidation products observed on pure ceria is decreased, and the low activity shown by silica is enhanced. For the CO+H₂ reaction, the addition of lanthana also generates upgraded products.