Preliminary animal and clinical experiences using an electromechanical endocardial mapping procedure to distinguish infarcted from healthy myocardium

BACKGROUND: A catheter-based left ventricular (LV) endocardial mapping procedure using electromagnetic field energy for positioning of the catheter tip was designed to acquire simultaneous measurements of endocardial voltage potentials and myocardial contractility. We investigated such a mapping system to distinguish between infarcted and normal myocardium in an animal infarction model and in patients with coronary artery disease. METHODS AND RESULTS: Measurements of LV endocardial unipolar (UP) and bipolar (BP) voltages and local endocardial shortening were derived from dogs at baseline (n=12), at 24 hours (n=6), and at 3 weeks (n=6) after occlusion of the left anterior descending coronary artery. Also, 12 patients with prior myocardial infarction (MI) and 12 control patients underwent the LV endocardial mapping study for assessment of electromechanical function in infarcted versus healthy myocardial regions. In the canine model, a significant decrease in voltage potentials was noted in the MI zone at 24 hours (UP, 42. 8+/-9.6 to 29.1+/-12.2 mV, P=0.007; BP, 11.6+/-2.3 to 4.9+/-1.2 mV, P<0.0001) and at 3 weeks (UP, 41.0+/-8.9 to 13.9+/-3.9 mV, P<0.0001; BP, 11.2+/-2.8 to 2.4+/-0.4 mV, P<0.0001). No change in voltage was noted in zones remote from MI. In patients with prior MI, the average voltage was 7.2+/-2.7 mV (UP)/1.4+/-0.7 mV (BP) in MI regions, 17.8+/-4.6 mV (UP)/4.5+/-1.1 mV (BP) in healthy zones remote from MI, and 19.7+/-4.4 mV (UP)/5.8+/-1.0 mV (BP) in control patients without prior MI (P<0.001 for MI values versus remote zones or control patients). In the canine model and patients, local endocardial shortening was significantly impaired in MI zones compared with controls. CONCLUSIONS: These preliminary data suggest that infarcted myocardium could be accurately diagnosed and distinguished from healthy myocardium by a reduction in both electrical voltage and mechanical activity. Such a diagnostic electromechanical mapping study might be clinically useful for accurate assessment of myocardial function and viability.     

Diameter of the cell-to-cell junctional membrane channels as probed with neutral molecules

The cell-to-cell channels in the junctions of an insect salivary gland and of insect and mammalian cells in culture were probed with fluorescent molecules-neutral linear oligosaccharides, neutral branched glycopeptides, and charged linear peptides. From the molecular dimensions of the largest permeants and smallest impermeants the permeation-limiting channel diameter was obtained: 16 to 20 angstroms for the mammalian cells and 20 to 30 angstroms for the insect cells.     

Probabilistic non-destructive assay of radioactive waste

Random loading of fissile material in radwaste containers may lead to significant uncertainty in the determination of the fissile content by non-destructive assay. An analytical procedure is developed for evaluating this uncertainty. The procedure is suitable for low fissile density, may be applied to single or multiple measurements and accounts for possible size distribution of the fissile particles. It is shown how the probabilistic interpretation of non-destructive assay depends fundamentally on the response function of the assay apparatus. This relationship is exploited to develop quantitative criteria for the degree of mass-resolution capability of the apparatus. These criteria provide useful guidelines for the optimal design of apparatus for non-destructive assay.     

A non-probabilistic concept of reliability

Uncertainty can be modelled either probabilistically or non-probabilistically. The former option leads to the concept of reliability as the probability of no-failure. In this paper non-probabilistic convex models of uncertainty are used to formulate reliability in terms of acceptable system performance given uncertain operating environment or uncertain geometrical imperfections. It is shown that probabilistic reliability can be very sensitive to small inaccuracy in the probabilistic model. Consequently, the non-probabilistic concept of reliability is useful when insufficient information is available for verifying a probabilistic model. In addition, a theorem is presented showing that analogous convex and probabilistic models of input uncertainty can lead to very different predictions of the range of output variation.     

Statistical analysis of “superresolving” methods for direction-of-arrival estimation of noise radiation sources under finite size of training sample

This paper addresses a detailed comparative study of operational performances of a family of the most prominent in the literature so-called “superresolution” methods for the estimation of spatial spectrum of Gaussian noise radiation sources impinging on an antenna array. Real-world operational scenarios are considered, in which small size samples are used for maximum likelihood estimation of the data correlation matrices. We perform an analysis of exact analytically derived and empirically evaluated distribution laws of random operational parameters that determine the resolution performances of the compared direction-of-arrival (DoA) superresolution estimation methods evaluated by statistical and non-statistical criteria. Our study reveals that in realistic scenarios with small size sample data these distribution laws may manifest a behavior significantly different from that theoretically predicted for asymptotic assumptions of “infinitely large” sample data recordings. The addressed detailed analysis of changes in behavior of such distribution laws provides the remedies for improvement of the convergence rates and robustness performances of the proposed modified superresolution procedures for feature-enhanced DoAs estimation of multiple noise radiation sources. The reported simulations corroborate the effectiveness of the proposed modified superresolution DoA estimation techniques.     

The modified SWAT model for predicting fecal coliforms in the Wachusett Reservoir Watershed, USA

This study assessed fecal coliform contamination in the Wachusett Reservoir Watershed in Massachusetts, USA using Soil and Water Assessment Tool (SWAT) because bacteria are one of the major water quality parameters of concern. The bacteria subroutine in SWAT, considering in-stream bacteria die-off only, was modified in this study to include solar radiation-associated die-off and the contribution of wildlife. The result of sensitivity analysis demonstrates that solar radiation is one of the most significant fate factors of fecal coliform. A water temperature-associated function to represent the contribution of beaver activity in the watershed to fecal contamination improved prediction accuracy. The modified SWAT model provides an improved estimate of bacteria from the watershed. Our approach will be useful for simulating bacterial concentrations to provide predictive and reliable information of fecal contamination thus facilitating the implementation of effective watershed management.     

A computer controller for vest cardiopulmonary resuscitation (CPR)

The authors recently developed a cardiopulmonary resuscitation (CPR) technique in which the airways are obstructed automatically during each chest wall compression. Energy loss accompanying air convection from the lungs during chest wall compression is limited so lung volume and intrathoracic pressures are increased. This technique required the development of a simple controller device to govern the pressure applied to ribcage and abdominal vests together with controller airflow at the airway opening. Experiments with the controller device on eight mongrel dogs showed that cardiac output increased obstructed expiratory cardiopulmonary resuscitation (OECPR) by 19% relative to the cardiac output during standard vest CPR (61% of the prearrest cardiac output relative to 24%, respectively). Furthermore, the OECPR technique without adjunct ventilation resolved the hypocapnic respiratory alkalosis that developed during the standard vest CPR with no ventilatory support. The authors give background information on the obstructed expiratory vest CPR and describe the controller device for delivering this CPR method     

The experimental contract: Subjects' expectations of and reactions to some behaviors of experimenters.

Hypothesized that experimental situations are role relationships in which Ss and Es hold sets of expectations about one another that constitute an implicit contract between them. In a series of 3 studies with 245 male and 184 female college students, it was found that Ss could articulate some of the clauses of this contract and that they had a repertoire of negative sanctions for violations of the agreement. The strength of Ss' expectations as well as the legitimacy and desirability of the E's behaviors were assessed. Ss exhibited general agreement about disliking violations of those clauses of the contract which were related to the E's professionalism. Results also demonstrate that when a violation is perceived, performance changes may occur even without deliberate retaliatory action on the part of the S. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lawler’s minmax cost algorithm: optimality conditions and uncertainty

The well-known \(O(n^2)\) minmax cost algorithm of Lawler (MANAGE SCI 19(5):544–546, 1973) was developed to minimize the maximum cost of jobs processed by a single machine under precedence constraints. We propose two results related to Lawler’s algorithm. Lawler’s algorithm delivers one specific optimal schedule while there can exist other optimal schedules. We present necessary and sufficient conditions for the optimality of a schedule for the problem with strictly increasing cost functions. The second result concerns the same scheduling problem under uncertainty. The cost function for each job is of a special decomposable form and depends on the job completion time and on an additional numerical parameter, for which only an interval of possible values is known. For this problem we derive an \(O(n^2)\) algorithm for constructing a schedule that minimizes the maximum regret criterion . To obtain this schedule, we use Lawler’s algorithm as a part of our technique.