Showing papers by "Drexel University published in 1970"

An Application of Signal Processing Techniques to the Study of Myoelectric Signals

Abstract: This paper describes the use of power spectral density and cumulative power functions in the examination of the electromyogram (EMG). The EMG signals were obtained with surface electrodes from two muscles, the flexor pollicis brevis and the extensor digitorum, in four subjects. Each muscle was studied at two levels of contraction, both before and during fatigue. The power spectral density functions are compared, using a cumulative power difference function and the mean frequency of the spectrum, to determine differences between loading conditions in an individual muscle, before and during fatigue, between different muscles, between individuals (same muscle), and combinations of these conditions.

Helical Twisting Power of Steroidal Solutes in Cholesteric Mesophases

Abstract: Helical twisting power of steroidal solutes in cholesteric mesophases, discussing nematic temperature shift dependence on ester chain

Effect of particle characteristics on soil strength

Abstract: The effects of varying particle characteristics on the strength behavior of cohesionless soils are experimentally evaluated Soil strength is measured on the basis of the angle of shearing resistance with dilatation removed These cohesionless soils were laboratory prepared from single minerals under closely controlled conditions It is shown that soil strength increases with increasing angularity and decreasing sphericity There is an increase in strength with decreasing effective size particularly with sizes less than 006 mm At a given relative density or void ratio the influence of different soil gradations has little effect on soil strength An approximate relationship for the corrected angle of shearing resistance is formulated

Mesoscale Weather Systems within an Occlusion

Abstract: Precipitation systems within a mature extratropical cyclone are related to the mesoscale thermal and circulation fields aloft using data from Project Stormy Spring conducted by the Air Force Cambridge Research Laboratories. Precipitation systems were analyzed using radars and recording raingages, including a special mesoscale array; upper-air structures were deduced from a 10-site mesoscale rawinsonde network including serial soundings at 90-min intervals. Results show that most of the widespread precipitation, in conjunction with the cyclonic-scale vertical motions in frontal baroclinic zones, occurs in bands and groups of showers. A sub-synoptic core of cold dry air in the middle troposphere ahead of the surface occlusion was found to be subsiding and surpressing wide-spread cloudiness, while it was furnishing a large amount of potential instability. The cyclone-scale ascending motions then released the potential instability around this cold core and also above the warm frontal stable layer. Th...

Magnesium sulfate in digitalis toxicity.

Abstract: This study was undertaken to evaluate the mechanism of the antiarrhythmic effect of magnesium sulfate in digitalis toxicity. The egress of potassium from the myocardium after the administration of 1 mg of acetyl strophanthidin into the right atrium was determined in 16 dogs by measurement of the coronary sinus-femoral artery potassium concentration difference. Three infusions of acetyl strophanthidin were given at 2 1 2 hour intervals. Twenty-five percent magnesium sulfate was given simultaneously with the third infusion. Arterial and coronary sinus samples were collected at 2 minute intervals after each infusion. The mean maximal arteriovenous potassium concentration difference was 0.47 mEq/liter after the first dose of acetyl strophanthidin and 0.80 mEq/liter after the second dose. When magnesium sulfate was given with acetyl strophanthidin, the arteriovenous difference was not significantly different from that of control subjects (0.15 mEq/ liter). A high level of magnesium concentration may overcome the acetyl strophanthidin-induced inhibition of transport adenosine triphosphatase. This may explain the efficacy of magnesium sulfate in the treatment of the arrhythmias of digitalis toxicity associated with hypomagnesemia. Although magnesium sulfate blocked myocardial egress of potassium in all studies, arrhythmias still occurred in 60 percent of the animals. This suggests that factors independent of potassium loss from the myocardium underlie the development of some digitoxic arrhythmias.

Disseminated intravascular coagulation—a complication of chemotherapy in acute myelomonocytic leukemia

Abstract: This is the first reported case of disseminated intravascular coagulation (DIC) occurring as a complication of chemotherapy in acute myelomonocytic leukemia. The DIC was successfully treated with heparin. Chemotherapy was continued, and a complete objective hematologic remission was obtained.

High temperature-high strain rate fracture of inconel 600

Abstract: The hot fracture of Inconel 600 has been studied over the temperature range from 800° to 2000°F using a hot torsion tester that is capable of superimposing either axial tensile or compressive stresses on the torsional shearing stresses. Microscopic studies of fracture initiation have been made over the entire temperature region. From 800° to 1200°F fracture initiates at inclusions and propagates by transgranular shear. In the temperature region of minimum ductility, 1300° to 1500°F, fracture initiates at grain boundaries and propagates readily in an intergranular manner. At 1600°F and above, fracture initiates easily at grain boundaries, but because recrys-tallization intervenes crack propagation is difficult and strain to fracture is high. Microcracks initiate at the peak in the torque-twist curve. The higher the temperature the smaller is the strain at which fracture initiates. Correlations have been found between the stress state and the shearing strain at crack initiation and total fracture strain. These correlations show the strong influence of a compressive normal stress on retarding crack initiation and resisting crack propagation.

Simultaneous Fibrinogen and Platelet’ Survival with [75Se]Selenomethionine in Man

Abstract: Summary. Simultaneous fibrinogen and platelet survivals were determined with a cohort label, [75Se]selenomethionine, in patients with hepatocellular disease and abnormal serial thrombin times (STT) and in control patients. The fibrinogen survival curves were divided into an anabolic and catabolic phase. In a control group maximum labelling of fibrinogen (anabolic phase) occurred within 24 hr and mean fibrinogen survival (catabolic phase) was 7.8 ± 2.8 days. Patients with hepatocellular disease fell into two groups, those with short fibrinogen survivals and those with normal fibrinogen survivals. In general, the more abnormal the STT the shorter the fibrinogen survival. The anabolic phase of the curve was also abnormal in that there was delay in incorporation of label in these patients. Average platelet survival in control patients was 10.6 ± 3.3 days and similar results were obtained in the patients with hepatocellular disease. In the latter no correlation was noted between platelet survival and fibrinogen survival. The data are consistent with the hypothesis that in hepatocellular disease fibrinogen anabolism is abnormal and short fibrinogen survival, when present, is due to either the production of an abnormal fibrinogen or defibrination or both.

Comparative mechanisms of antiarrhythmic agents

Abstract: Treatment of arrhythmias is best understood if viewed from 2 major electrophysiologic standpoints: disturbances of impulse formation and disturbances of impulse conduction, or both. Arrhythmias secondary to enhanced automaticity are best controlled by agents depressing diastolic depolarization (quinidine, lidocaine and propranolol). Arrhythmias secondary to depressed conduction can be terminated by (1) enhancing conduction velocity by hyperpolarization (bretylium) or increase in membrane responsiveness (diphenylhydantoin) or (2) by further depressing conduction (quinidine and propranolol). Simple prolongation of the effective refractory period can also interrupt reentry. Direct antifibrillatory effects of high levels of potassium are demonstrated. Specific effects on intraatrial, intranodal and subnodal conduction and ineffectiveness of certain antiarrhythmic agents such as lidocaine in the presence of low levels of potassium are also discussed.

The histopathology of bronchogenic carcinoma and its relation to growth rate, metastasis, and prognosis.

Abstract: During the course of a prospective study in which 6,136 older men were examined by photofluorogram and questionnaire every 6 months, 179 developed proved bronchogenic carcinoma. Histologic sections were obtained in 161 cases and classified by a panel of 3 pathologists using a modified World Health Organization classification. The panel agreed with the diagnoses made by the hospital pathologists in most of those originally classified as squamous cell or adenocarcinoma but classified 30% of the undifferentiated carcinomas as squamous cell tumors. The panelists placed most of these in the anaplastic subgroup (lc). Unanimity was highest for squamous cell carcinoma and within this group the extent of agreement was best for the most highly differentiated subgroup (la). Five‐year survival rates were poor (10%), but equal for men with squamous cell and adenocarcinoma. These findings can be explained by the biologic character of the cancer types; squamous cell carcinomas have rapid growth rates and moderate metastatic potential, while adenocarcinomas have slow growth rates but high metastatic potential.

Pleomorphic spindle-cell carcinoma of the gallbladder. Relation to sarcoma of the gallbladder

Abstract: Two cases of an unusual plemomorphic spindle-cell form of carcinoma of the gallbladder are described. These neoplasms are probably identical to many previously reported as sarcomas. They generally occur in older women with associated cholelithiasis. Their microscopic features include extensive roundto-spindle cell proliferation without stromal differentation and areas of differentiated adenocarcinoma which may be obscured by the great bulk of anaplastic tumor.

Polymerization of a Nematic Liquid Crystal Monomer

Abstract: The purpose of this study was to ascertain whether a single component liquid crystalline phase represents an ordered matrix in which topochemical control can be exercised in intermolecular reactions. A detailed kinetic study of the polymerization of the new nematic liquid crystal monomer N-(p-methoxy-o-hydroxy-benzylidene)-p-aminostyrene was conducted in the nematic and isotropic phases. In addition, the polymerization in the nematic phase was conducted in a magnetic field of 1300 Oe. In disagreement with previous reports on other liquid crystal systems, no significant effect on the rates of polymerization or the nature of the product appears to be associated with the existence of the nematic phase or the presence of a magnetic field during the reaction.

Metallic modified plastic compositions and method for the preparation thereof

Abstract: D R A W I N G METALLIC MODIFIED PALSTIC COMPOSITION ARE PROVIDED WHICH ARE COMPRISED OF A PLASTIC MATRIX CONSISTING OF ADHERED PLASTIC PARTICLES HAVING AN AVERAGE SIZE FROM 20100 MICRONS AND AT LEAST 5% BY VOLUME OF A CONDUCTIVE METAL. THE METAL IS DISPERSED THROUGHOUT THE PLASTIC MATRIX IN CONDUCTIVE PATHS IN THE INTERSTICES BETWEEN THE ADHERED PLASTIC PARTICLES OF THE MATRIX. THE METAL PARTICLES HAVE AN AVERAGE PARTICLE SIZE WHICH IS AT LEAST ABOUT 1/10 THAT OF THE PLASTIC PARTICLES UTILIZED TO FORM THE PASTIC MATRIX. THE METALLIC MODIFIED PLASTICS OF THIS INVENTION ARE ESPECIALLY USEFUL AS ELECTRICAL CONDUCTORS AND ARE ALSO USEFUL IN APPLICATIONS REQUIRING PLASTICS HAVING HIGH HEAT CONDUCTIVITY AND MECHANICAL STRENGTH.

Deformation behavior of continuous-fiber metal-matrix composite materials

Abstract: The deformation behavior of continuous-fiber, metal-matrix composites was studied in terms ofin situ deformation behavior of the matrix and the fibers. X-ray diffraction techniques were employed to monitor the stress-strain behavior of the composite components (matrix and fibers) as a function of total composite stress-strain behavior. This experimental technique provided a unique approach to the study of metal-matrix composites since the deformation response of the components could be measuredin situ while the composite was under load. Furthermore, the influence of residual stress, component mechanical properties, and stress interactions between the matrix and the fibers could be incorporated into the analysis of composite deformation behavior. The study was conducted on composites of 2024 aluminum reinforced with tungsten fibers, and composites of 2024 aluminum reinforced with boron fibers. Composites were tested on a specially-designed, tensile device which served as a diffractometer specimen holder such that diffraction experiments could be performed while the specimen was incrementally deformed in uniaxial tension. Experimental results indicated that, except for the residual stress effects, the composites exhibited rule-of-mixture s behavior in the stage I, II, and in deformation regions. Measurements obtained perpendicular to the fiber and tensile axis during the tensile tests indicated that negligible stresses were developed as a result of Poisson’s ratio differences between the matrix and the fibers. Composite yield behavior was significantly influenced by residual stresses present in the individual components. Residual stresses parallel to the fiber axis could be included in the rule-of-mixtures analysis by considering the amount of prestrain which was present in each component.

Tris-(isopropoxy methylphosphonato) complexes of trivalent rare-earth metal ions

Abstract: Tris-(isopropoxy methylphosphonato) rare earth complexes were obtained by interaction of diisopropyl methylphosphonate with trivalent rare-earth chlorides at 50 °–100 °C. The complexes were characterized by means of infrared, magnetic and X-ray powder diffraction studies. A distorted Oh symmetry is assigned to the metal ions. Far infrared evidence indicates the presence of strong lanthanide (III)-oxygen bonds, possibly having partially covalent character. Possible structures of the new complexes, including monomeric chelates and oligomers or polymers, involving eight-membered phosphonate bridges and four-membered chelate rings, are discussed.

Dipole Relaxation in a Liquid Crystal

Abstract: Liquid crystal of cholesteryl chloride and myristate measured for complex dielectric constant, noting role of molecular rotation modes in dipole relaxation

Coronary artery-coronary sinus fistula.

Abstract: Two cases of coronary artery-coronary sinus fistula are reported. A review of the literature is presented, and the data of the reported cases are analyzed. A continuous murmur has been described in most of the cases, and factors that may modify the character of the murmur are discussed. Cardiac X-ray films usually show a prominent main pulmonary artery, left or right ventricular enlargement and increased or normal pulmonary vascularity depending on the degree of the shunt. The electrocardiogram usually shows left ventricular hypertrophy and ischemia or incomplete right bundle branch block. Cardiac catheterization shows a step-up of oxygen content at the atrial level, and dye-dilution curves are diagnostic of left to right shunt. The only accurate methods for diagnosis are aortography and selective coronary arteriography. The treatment of choice is surgical correction of the anomaly at the time of the diagnosis.