PMMA tacticity and alumina powder dispersion stability

Summary Sedimentation experiments and X-ray photoelectron spectroscopy (XPS or ESCA) analyses have been used to study the effect of poly(methylmethacrylate) (PMMA) tacticity on aluminum oxide powder dispersion stability in a common solvent medium. The relative trends from sedimentation densities, and from surface analyses after solvent washing show that (PMMA) adsorption is greatest with isotactic polymer, where isotactic>atactic>syndiotactic adsorption. These results suggest that surface adsorption and hence dispersion stability can be influenced by polymer chain configuration as well as by chain conformation.     

Concentration-response relationships for adenosine agonists during preconditioning of rabbit cardiomyocytes

Although adenosine receptors have been implicated in the induction of preconditioning in a variety of experimental models, there is controversy concerning the specific adenosine receptor subtypes mediating this effect. Concentration-protection relationships for adenosine and adenosine agonists in rabbit cardiomyocytes were used to characterize the role of adenosine receptor subtypes in preconditioning. Isolated cells were ischemically preconditioned or pre-incubated for 10 min with increasing concentrations of adenosine, CCPA (2-chloro-N6-cyclopentyladenosine), APNEA (N6-2-(4-aminophenyl)ethyladenosine), or BNECA (N6-benzyl-5'-N-ethyl-carboxamidoadenosine) in the presence or absence of 1 or 10 microM of the selective A1-adenosine antagonist DPCPX (8-Cyclopentyl-1,3-dipropylxanthine). Following a 30-min post-incubation period, cells were pelleted, layered with oil and ischemically incubated for 180 min. Injury was assessed by osmotic swelling and trypan blue exclusion of sequential samples, and determination of the areas beneath the mortality curves. Adenosine produced a broad concentration-protection curve which was displaced to the right by DPCPX. The curve for A1-selective agonist CCPA was biphasic, with an initial response below 1 nM and a second above 1 microM. DPCPX abolished the early response leaving a steep monophasic curve between 0.1 and 10 microM CCPA. The APNEA curve appeared moriophasic, the major slope occurring between 1-100 nM; DPCPX (1 microM) shifted the concentration-response curve approximately 30-fold and decreased the slope. Adenosine receptor agonist BNECA produced preconditioning characterized by a shallow monophasic concentration-protection curve with a maximal effect of 49% and an EC50 of approximately 5 nM; DPCPX shifted the BNECA concentration-protection relationship approximately 40-fold with only a modest increase in slope. Analysis of the data suggests that induction of preconditioning results from interaction of agonists with the A1 receptor and a second adenosine receptor having properties consistent with the A3 receptor. Adenosine, CCPA, APNEA, BNECA and DPCPX each appear to be selective for the A1 adenosine receptor subtype in isolated rabbit cardiomyocytes.     

The Second Canadian Gastroesophageal Reflux Disease Consensus: moving forward to new concepts

Gastroesophageal reflux disease (GERD) is a disease with serious consequences that may result in significant impairment in quality of life and disease morbidity. Across all grades of severity of symptoms and severity of underlying esophageal disease, proton pump inhibitors (PPIs) provide therapeutic gains over prokinetics (PKs) or H2 receptor antagonists (H2RAs). The potential cost effectiveness of using medications with higher acquisition costs that may lower health care costs overall is often disregarded when conducting cost comparisons with medications having lower 'up-front' costs. Limiting therapy to less effective agents condemns many patients to protracted suffering, repeated physician visits and needless reinvestigation of symptoms that could have been resolved by appropriate initial therapy. Based on current data, use of any classification of symptom severity as a basis for selecting one class of therapeutic agents over another for first line therapy (i.e. PKs, H2RAs for 'mild' GERD, versus a PPI for 'severe' disease) is unwarranted.     

A greedy algorithm to determine the number of transporters in a cyclic electroplating process

This paper presents a local optimization algorithm for minimizing the number of transporters required for material handling in a cyclic processing line. Within a cycle, a given set of transportation operations must be performed. Each operation consists of picking up a work-in-process job at a stage and delivering it to the next stage. The length of time that a job can remain at a particular stage is restricted by a time window. The transporters that perform the operations move on a shared track, and traffic collisions must be avoided during their movements. To avoid traffic collisions, the operations are partitioned into groups, where each group is served by a single transporter. A local optimal solution is obtained when the group sizes are maximized. We show that the duals of the linear programming subproblems formulated in the process of maximizing the group sizes are specially structured shortest-path problems. This leads to an effective search method for the maximization problem. Conditions when die proposed algorithm achieves die global optimal solution are discussed. The algorithm's performance is evaluated on both randomly generated test problems and benchmark problems.     

The effect of LH, FSH and pregnant mares' serum gonadotrophin on ornithine decarboxylase activity in thecal and granulosa tissue during follicular growth and atresia in laying hens (Gallus domesticus)

The effect of ovine LH, porcine FSH and pregnant mares' serum gonadotrophin (PMSG) on the activity of ornithine decarboxylase activity in theca and granulosa tissue during folliculogenesis in laying hens is described. The changes in the activity of ornithine decarboxylase induced by hormonal challenge was used to measure the sensitivity of the tissue to the hormone. Thecal tissue from small (< 6 mm) follicles showed a large increase in the activity of ornithine decarboxylase 3 h after treatment with LH, FSH and PMSG, in vivo, whereas ornithine decarboxylase activity in thecal tissue from large (> 8 mm) preovulatory follicles and atretic follicles did not respond to any of the hormonal treatments. Ornithine decarboxylase activity in granulosa tissue from the largest preovulatory follicle increased significantly 3 h after treatment with LH and PMSG in vivo; no effect was observed with FSH. Granulosa tissue from the third largest and fifth largest preovulatory follicles were refractory to the hormonal treatments. Basal activity of ornithine decarboxylase in granulosa tissue from preovulatory follicles increased as the follicles approached ovulation, whereas the activity in thecal tissue from the same follicles decreased. The difference in sensitivity of thecal tissue from small and large preovulatory follicles towards gonadotrophin treatment in vivo is correlated with the difference in the observed rate of atresia occurring within the two groups of follicles. Atresia is the common fate for small follicles, whereas it is a rare event for large preovulatory follicles under normal physiological conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Machine learning in control of functional electrical stimulationsystems for locomotion

Two machine learning techniques were evaluated for automatic design of a rule-based control of functional electrical stimulation (FES) for locomotion of spinal cord injured humans. The task was to learn the invariant characteristics of the relationship between sensory information and the FES-control signal by using off-line supervised training. Sensory signals were recorded using pressure sensors installed in the insoles of a subject's shoes and goniometers attached across the joints of the affected leg. The FES-control consisted of pulses corresponding to time intervals when the subject pressed on the manual push-button to deliver the stimulation during FES-assisted ambulation. The machine learning techniques used were the adaptive logic network (ALN) and the inductive learning algorithm (IL). Results to date suggest that, given the same training data, the IL learned faster than the ALN while both performed the test rapidly. The generalization was estimated by measuring the test errors and it was better with an ALN, especially if past points were used to reflect the time dimension. Both techniques were able to predict future stimulation events. An advantage of the ALN over the IL was that ALN's can be retrained with new data without losing previously collected knowledge. The advantages of the IL over the ALN were that the IL produces small, explicit, comprehensible trees and that the relative importance of each sensory contribution can be quantified     

Anthropometric data for describing the kinematics of the human hand.

The major goal of this investigation was to collect statistically-based anthropometry describing the kinematics of the human hand and to model this anthropometry as a function of external hand measurements, so that it may be predicted noninvasively. Joint centres were anatomically estimated as the centre of curvature of the head of the bone proximal to the given joint. Joint centres determined using Reuleaux's method for PIP and DIP were within 1.4 mm of this anatomical estimate. Models using bone length as the independent variable explain more than 97% of the variability in the anatomically estimated joint centre position along the mid-line of the bone. Models for estimating the lengths of the kinematic segments using external hand length as the independent variable account for between 49 and 99% of the variability in segment length. Models for estimating the axial location of the finger MCP and thumb CMC joints with respect to the distal wrist crease using external hand length as the independent variable account for between 82 and 96% of the variability in these locations. Models for estimating the radio-ulnar location of the finger MCP and thumb CMC joints with respect to the long axis of the third metacarpal using external hand breadth as the independent variable account for between 30 and 74% of the variability in these locations.     

Global self-ratings of health and mortality: hazard in the North Carolina Piedmont

We analyzed the first 5 years of surveillance data from the Established Population for the Epidemiologic Studies of the Elderly (EPESE) in the Piedmont of North Carolina (n = 4162) to estimate the effect of a global self-rating of health on survival. Covariates used in Cox proportional hazard models included sociodemographic factors, chronic medical conditions, activities of daily living, use of health services, health risk behaviors, cognitive function, affective mood, and negative life events. Adjusted risk of mortality associated with poor (compared to excellent) self-ratings of health was significantly elevated among urban men only. Confounders of the association between survival and overall health assessment varied widely by subgroup. Pooled estimates from heterogeneous populations may mask significant subgroup differences both in the pattern of variables that mediate crude risk and also in the magnitude of residual risk of global self-ratings of health.