Showing papers by "University of Illinois at Chicago published in 1971"
TL;DR: In this article, an equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus-Yevick integral equation.
Abstract: An equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus–Yevick integral equation for the mixture of hard spheres. Compressibility and other equilibrium properties of the binary mixtures of hard spheres are calculated and they are compared with the related machine‐calculated (Monte Carlo and molecular dynamics) data. The comparison shows excellent agreement between the proposed equation of state and the machine‐calculated data.
1,894 citations
TL;DR: In conclusion, abnormalities of conduction and automaticity in specialized tissue in addition to the sinus node are common in patients with symptomatic sinus nodes disease and should be recognized when present, so that the ideal site for permanent pacing may be chosen.
Abstract: Cardiac conduction was investigated at the time of pacemaker insertion in 15 patients with symptomatic sinus node disease. Techniques included recording of His bundle potentials, atrial pacing at various heart rates, and atropine administration. Atrioventricular (AV) conduction was impaired in eight patients who manifested one or more of the following: P-R prolongation, P-H prolongation, and development of second degree AV block with atrial pacing at heart rates below 130 beats/min. Five patients had intraventricular conduction defects diagnosed electrocardiographically; none of these had H-Q prolongation. One of these five, with left bundle-branch block, subsequently developed complete heart block and had a calcific lesion involving the His bundle. Depression of cardiac automaticity was noted in four patients, with asystolic periods greater than 2 sec after sudden cessation of atrial pacing at rates of 100-160 beats/min. Responses to 1 mg of intravenous atropine were varied, but no patient developed sinus rates greater than 90 beats/min, suggesting the presence of primary sinus node dysfunction.
In conclusion, abnormalities of conduction and automaticity in specialized tissue in addition to the sinus node are common in patients with symptomatic sinus node disease. These abnormalities should be recognized when present, so that the ideal site for permanent pacing may be chosen.
251 citations
TL;DR: In this article, the volume change behavior of sands under cyclic loading simple shear conditions was studied and it was shown that the vertical strain due to compaction depends only on the shear strain amplitude induced in the sample at strains exceeding 0.05%.
Abstract: Measurements of the volume change behavior of sands under cyclic loading simple shear conditions suggest that the vertical strain due to compaction depends only on the shear strain amplitude induced in the sample at strains exceeding 0.05%. This indicates that cyclic shear strain, which deforms the sample allowing particles to move into denser packing, may well be a fundamental parameter in determining the volume change behavior of cohesionless soils under dynamic loading conditions. Quantitative data also showed that there was significantly more volume change for sand at relative densities below 60%. In addition, the importance of the first few strain cycles in determining the total vertical strain in the sample was indicated by the fact that for the range of test parameters studied, as much vertical settlement due to compaction occurs in the first 10 cycles as occurs in the next 40 cycles. The test data may be used to evaluate the possible magnitude of ground surface settlements due to ground shaking caused by earthquakes or other types of ground vibrations.
234 citations
TL;DR: This paper presents seven techniques for choosing good subsets of properties and compares their performance on a nine-class vectorcardiogram classification problem.
Abstract: The only guaranteed technique for choosing the best subset of N properties from a set of M is to try all (MN) possible combinations. This is computationally impractical for sets of even moderate size, so heuristic techniques are required. This paper presents seven techniques for choosing good subsets of properties and compares their performance on a nine-class vectorcardiogram classification problem.
215 citations
TL;DR: The number and nature of these compounds suggests that metabolic intermediates exert a cumulative effect on the activity of the triose-P isomerases, acting concertedly to modulate the activityof these enzymes in the green leaf.
208 citations
TL;DR: The Platte is a wide, shallow river which flows eastward from the Rocky Mountains across the Great Plains of Nebraska and during intermediate and low discharges displays a pronounced braided character accomplished primarily through dissection of tabular, flat-topped transverse bars as mentioned in this paper.
Abstract: The Platte is a wide, shallow river which flows eastward from the Rocky Mountains across the Great Plains of Nebraska. Its lower reaches carry a dominantly sandy load and during intermediate and low discharges display a pronounced braided character accomplished primarily through dissection of tabular, flat-topped transverse bars.
Transverse bars form by sediment aggrading to a profile of equilibrium (Jopling, 1966) and grow by downcurrent extensions of avalanche faces. Depth, velocity, and grain size tend to decrease on active bar surfaces from their upstream mouths to the downstream and lateral margins. Active surfaces are covered with small-scale bed forms whose distributions are controlled by the flow characteristics. A typical mouth-to-margin bed form progression is dunes to diminished dunes to ripples, reflecting downcurrent reduction of stream power. Water-surface slopes over active bars tend to be greater than those of the channel segments which feed them.
Under ideal conditions, transverse bars are essentially lobate; however, most bars, especially during low discharges, assume irregular or asymmetrical patterns due to any of several factors that include bar-mouth cross-sectional geometry, proximity to exposed banks, adjacent currents, steadiness of flow, and basin depth distribution. Braiding (bar dissection) begins during decreasing discharges when the flow passing through the bar mouth becomes unable to sustain active sediment transport over the entire bar surface. A single bar, examined closely over a five-day period of gradually decreasing discharge, documents the evolution from wholly active to dissected states.
206 citations
TL;DR: The character theory of finite groups has been studied in this article for infinite-dimensional Hopf algebras, where characters are defined as elements of the Hopf algebra which are associated with comodules over Hopf.
176 citations
TL;DR: Dosage of gentamicin based upon the weight of the patient produced a wide range of concentrations of the drug in serum, and individual patterns in the response to dose were observed to be accelerated, typical, or dampened, giving brief high, average, or low levels ofdrug in serum.
Abstract: Dosage of gentamicin based upon the weight of the patient (1.5-8 mg/kg per day) produced a wide range of concentrations of the drug in serum. In 10% of patients, the level is potentially toxic, but in 30% it is inadequate for therapy. Concentrations of gentamicin in urine are high, in cerebrospinal fluid low, and in bile, pleural, and pericardial fluid one-half to one-fourth that in the serum. Renal insufficiency requires an altered maintenance dosage. Hemodialysis clears gentamicin at a rate equal to 60% of that at which creatinine is cleared. Individual patterns in the response to dose were observed to be accelerated, typical, or dampened, giving brief high, average, or low levels of drug in serum. A significant inverse relation exists between the level of gentamicin in serum and hematocrit. Studies with radioactive gentamicin (100 ztg/ml) showed that 10% was associated with erythrocytes, 30% with plasma proteins, and 60% in solution. The individual dose-responses emphasize the value of monitoring gentamicin levels in serum during treatment. The optimal clinical benefit from treatment of infections caused by organisms sensitive to gentamicin can be obtained only if the dose used provides a therapeutic, but not a toxic, level in the blood. To achieve this goal, it is essential to have information concerning the factors and conditions that influence the concentration of drug in the plasma and the penetration of the drug into various compartments of body fluids. Because gentamicin is not appreciably metabolized or inactivated in the body, the principal determinants of the level in plasma attained with any given dose are the absorption, binding, distribution, and excretion of the drug. The major, if not the exclusive route of elimination of gentamicin from the body is through the kidneys by glomerular fil
172 citations
TL;DR: In this paper, the equilibrium density, binding energy and elastic constants of amorphous metals are investigated using the approximation of pairwise central interatomic potentials, and the importance of the internal displacements is found to make significant contributions to the shear elastic constant.
170 citations
TL;DR: Dopamine improves MAP pressure, CO, and UF when shock is due to infection and is superior to Isp which does not increase perfusion pressure to adequate levels and does not improve UF.
Abstract: The hemodynamic effects of dopamine were studied in 62 patients with clinical shock. In 36 patients with infection dopamine increased mean arterial pressure (MAP) 30%, and cardiac output (CO) 37%. Urine flow (UF) increased from 0.5 ml/min to 1.6 ml/min. Norepinephrine (NE) in 26 patients resulted in a higher MAP, lower CO, and similar UF. Isoproterenol (Isp) in 19 patients resulted in a lower MAP, higher CO, and a significantly lower UF. In 13 patients with cardiogenic shock dopamine increased MAP 6%, and CO 40%. UF increased from 0.6 ml/min to 1.1 ml/min. NE in eight patients resulted in a lower CO than during dopamine infusion, and Isp in five patients resulted in a higher CO. Dopamine improves MAP pressure, CO, and UF when shock is due to infection and is superior to Isp which does not increase perfusion pressure to adequate levels and does not improve UF. In patients with cardiogenic shock who have reduced CO and increased systemic vascular resistance, perfusion pressure tended to be adequate, and imp...
167 citations
TL;DR: The species Pseudomonas aeruginosa is sensitive to gentamicin, but among 21 patients treated for pseudomonas bacteremia, only six were cured and 15 died, while the protective level in serum corroborated the in-vitro sensitivity tests.
Abstract: The species Pseudomonas aeruginosa is sensitive to gentamicin, but among 21 patients treated for pseudomonas bacteremia, only six were cured and 15 (71%) died. Seven patients with a rapidly fatal underlying disease died; five of eight considered to have ultimately fatal diseases died, and three of six patients with nonfatal primary diseases died. The dose was not predictive of the level in serum, and most patients received a suboptimal dose. The concentration in the serum was directly related to eradication of bacteremia and survival of the patient. The protective level in serum corroborated the in-vitro sensitivity tests. Gentamicin had a slow maximal bactericidal rate on Pseudomonas. Leukemic leukocytes in leukemic serum were less effective than normal leukocytes in normal serum in killing P. aeruginosa. The high fatality rate from pseudomonas bacteremia results from inadequate treatment, resistance of the organism to killing, and defective defense mechanisms in the patients. Proper use of gentamicin should cure patients if they do not have fatal underlying diseases.
TL;DR: Until more valid, empirical evidence on at least a few standard drugs can be accumulated, it seems necessary to include a placebo condition in each drug study.
Abstract: Publisher Summary This chapter discusses the methodology of psychopharmacological studies with the retarded. Until more valid, empirical evidence on at least a few standard drugs can be accumulated, it seems necessary to include a placebo condition in each drug study. If it is wished to estimate the placebo effects of a certain type of administration on a certain type of population, then it follows logically that a no-drug (ND) condition should also be used. Assignment of the subjects to the experimental conditions should not depend upon the hunches or other idiosyncratic procedures of a particular investigator, for this may seriously bias the sample. Unless the dosage of a drug is standardized in some manner for some period of time, it is impossible to obtain any worthwhile information from the study about the effects of dosage. Because dosage is always assumed to be a very important variable, it seems absolutely necessary to use some kind of standardized dosage procedure. Moreover, it is not sufficient simply to list the percentage figures about the degree of improvement in a drug study. Such data are next to impossible to interpret operationally and are seldom subject to scientifically valid tests of replicability.
TL;DR: Most patients with PR prolongation and intraventricular conduction defects had prolongation of P-H, suggesting A-V nodal disease and patients with LBBB usually had significant H-Q prolongation, suggesting bilateral bundle-branch disease.
Abstract: His bundle electrograms (H) were recorded in 27 patients with PR prolongation and intraventricular conduction disturbances. The PR interval was subdivided into P-H (normal 80-140 msec), a measure of atrioventricular (A-V) conduction, and H-Q (normal 35-55 msec), a measure of intraventricular conduction. In 12 patients with left bundle-branch block (LBBB), P-H varied from 115-410 msec (mean 173 msec), and was prolonged in eight patients. H-Q varied from 39-125 msec (mean 80 msec), and was prolonged in 10 patients. In eight patients with right bundle-branch block (RBBB), P-H varied from 146-450 msec (mean 206 msec), and was prolonged in all patients. H-Q ranged from 41-65 msec (mean 51 msec), and was slightly prolonged in three patients, all of whom had, in addition, evidence of left anterior or posterior hemiblock. Seven patients with lesser intraventricular conduction defects all had prolonged P-H intervals, with normal H-Q intervals. With atrial pacing at increased heart rates, block proximal to H occurr...
TL;DR: In this paper, a bogus personality trait scale was administered to subjects, and they were either informed of the range of scores in their group (R conditions) or not informed (NR conditions).
TL;DR: Postmortem examination revealed a previously undescribed atrial disease characterized by arteriolosclerosis, fibroelastosis, fatty infiltration, and vacuolar degeneration of muscle cells, with only moderate SA and A-V nodal involvement.
Abstract: Electrophysiologic studies, including His bundle recording and atrial pacing (AP), were performed in one patient with transient (TAS) and another with persistent atrial standstill (PAS). Both subse...
TL;DR: Skin permeability in preterm infants was evaluated by observing the blanching response to topically applied 10 per cent Neo-Synephrine and data suggest immature barrier function in the epidermis of the preterm infant.
TL;DR: In this article, the authors argue that a marketing system that maximizes individual choice and stresses individual satisfaction is anachronistic in a world with growing awareness of its limited environmental resources.
Abstract: Is a marketing system that maximizes individual choice and stresses individual satisfaction anachronistic in a world with growing awareness of its limited environmental resources? The author believ...
TL;DR: In this article, the applicability of Griffith fracture criteria to portland cement systems which are neither elastic nor homogeneous was examined. But it appears that for mortar and concrete the direct application of Griffith criteria is not valid up to a certain length of cracks, depending on the size, volume and type of aggregate.
Abstract: The original Griffith fracture criteria was developed to describe the rapid extension of a crack in a homogeneous elastic body. To check the applicability of the Griffith theory to portland cement systems which are neither elastic nor homogeneous, specimens of hardened cement paste, mortar and concrete made with normal and lightweight aggregates, and with notches of varying lengths were tested in flexure and in tension. While the paste specimens were notch-sensitive, mortar and concrete strengths were independent of notch length. The notch-insensitivity of mortar and concrete appears to be due to their composite nature. Similar behavior occurs in glass-Al²O³, fiberglass-reinforced epoxy and tungsten-reinforced copper composites. It appears that for mortar and concrete the direct application of Griffith criteria is not valid up to a certain length of cracks. This critical length depends on the size, volume, and type of aggregate.
TL;DR: A new syndrome which combines clinical features of several storage diseases, but which is nonetheless unique, is characterized by autosomal recessive inheritance and the presence of dwarfism, gargoyle facies, mental retardation, seizures, corneal clouding, macular cherry-red spot, β-galactosidase deficiency, dysostosis multiplex, and hearing deficit.
Abstract: A new syndrome which combines clinical features of several storage diseases (mucopolysaccharidoses, sphingolipidoses, and mucolipidoses), but which is nonetheless unique, is characterized by autosomal recessive inheritance and thepresenceof dwarfism, gargoyle facies, mental retardation, seizures, corneal clouding, macular cherry-red spot, β-galactosidase deficiency, dysostosis multiplex, and hearing deficit. It is also characterized by theabsenceof clinically enlarged organs, vacuolated blood cells, and mucopolysacchariduria.
TL;DR: The purpose of this investigation is to determine the directional correlation of successive dispersal events, and establish the extent to which pollinator directionality increases pollen flow.
Abstract: 113 Pollen flow in entomophilous plants is a function of pollinator flight distance, pollen deposition schedule, and directionality of successive pollinator flights. If all pollen is deposited on the first recipient so that there is no carry-over, the pollen dispersal distance will be equivalent to the pollinator flight distance. If pollen is carried beyond the first recipient, the dispersal distance will be greater than the flight distance, the differential depending on the carry-over schedule and degree of flight directionality. Once these parameters are known, constants may be employed to modify flight statistics for estimating dispersal parameters. Unfortunately, there is no information from which to calculate these constants for any given plant-pollinator combination. The purpose of this investigation is to determine the directional correlation of successive dispersal events, and establish the extent to which pollinator directionality increases pollen flow. This study was given priority to one dealing with carry-over because directional trends associated with foraging are determined by the pollinator rather than the plant species and therefore are similar for many plants with a common pollinating insect. On the other hand, the pollen carry-over schedule depends upon the construction of the floral mechanism, amount of pollen shed and pollen attributes which might affect its transport, and the locus of pollen transport. These factors will vary from one plant-pollinator combination to another, and thus provide little information of general applicability.
TL;DR: It is concluded that the proximal left and right bundle branches are usually activated simultaneously in man, and that block of either bundle without contralateral bundle delay does not significantly delay the onset of ventricular activation.
Abstract: His (H), right bundle branch (RB), and left bundle branch (LB) potentials were recorded by electrode catheters passed into the left and right ventricles in seven patients without conduction defects In another three patients, H and LB were recorded Initial ventricular activation was considered to coincide with the onset of the QRS (Q) The following intervals were measured in milliseconds: H-Q, LB-Q, RB-Q, H-LB, H-RB, and LB-RB The average and range of these was as follows: H-Q 46 (39-54), LB-Q 27 (24-30), RB-Q 25 (20-27), H-LB 20 (14-28), H-RB 21 (15-29), and LB-RB 2 (1-10) LB-RB was 3 msec or less in six of seven patients Coupled atrial pacing produced delays in H-RB without effect on H-LB and LB-Q The production of incomplete and complete right bundle branch block was related to increase in the LB-RB interval One patient developed left bundle branch block (LBBB) during coupled pacing with delay of LB while RB-Q remained unchanged H-Q intervals were measured in three additional patients with rate related LBBB during both control and block Prolongation of H-Q was less than 3 msec during LBBB It is concluded that the proximal left and right bundle branches are usually activated simultaneously in man, and that block of either bundle without contralateral bundle delay does not significantly delay the onset of ventricular activation
TL;DR: Electron microscopic studies of oogenesis in Drosophila melanogaster suggest that the ovarian follicle cells alone are responsible for the secretion of the vitelline membrane and chorion, but under certain aberrant conditions, other cell types may serve to induce formation of these membranes.
Abstract: Electron microscopic studies of oogenesis in Drosophila melanogaster suggest that the ovarian follicle cells alone are responsible for the secretion of the vitelline membrane and chorion. The synthesis and assembly of the vitelline membrane is a complex process involving several stages of development and different populations of follicle cells. This combined autoradiographic and ultrastructural investigation of vitelline membrane formation has led to the conclusion that the protein component of the vitelline membrane is synthesized in the follicle cells, and that these cells possess a mechanism which directs the polarized synthesis and deposition of vitelline membrane and chorion in response to contact by a specific cell, the oocyte. Under certain aberrant conditions, however, other cell types may serve to induce formation of these membranes. The concept of Drosophila egg coverings as maternal cuticle is also discussed, with regard to the embryonic origin of secreting cells, the requirement for adjacent cells as inducers, and the differences in ultrastructural mechanisms of formation.
TL;DR: Electron microscopic study of a granular cell tumor of the urinary bladder revealed myofilaments in the tumor cells, documenting the myogenous derivation of this neoplasm.
Abstract: Electron microscopic study of a granular cell tumor of the urinary bladder revealed myofilaments in the tumor cells, documenting the myogenous derivation of this neoplasm. This is in contrast to the ultrastructural features of the common variety of granular cell tumors, currently interpreted as being indicative of a schwannian histogenesis. The granules of these tumors are similar in ultrastructural appearance regardless of the location of the neoplasms, and are reminiscent of lysosomes and cytosegresomes. It is suggested that granular cell tumors may derive from different cell types.
TL;DR: The subjective symptoms were reported as improved most frequently, whereas the more objective symptoms seemed less affected by either the meprobamate or the placebo.
Abstract: Patients experiencing the symptoms of pain, tenderness, clicking, and limitation of function, which characterize the myofascial pain-dysfunction (MPD) syndrome have been subjected over the years to a variety of therapeutic measures. An investigation was made of the effectiveness of meprobamate in treatment of the MPD syndrome. Of the 90 patients studied, 58% reported some improvement after taking the drug, and 31% after taking a placebo. The subjective symptoms were reported as improved most frequently, whereas the more objective symptoms seemed less affected by either the meprobamate or the placebo.
TL;DR: Mild exercise prolongs left ventricular ejection in patients with angina, which contributes to the development of angina and has value in its diagnosis.
Abstract: The effects of a 4-min exercise on the duration of the systolic time intervals were determined in 20 patients with angina and 20 age-matched normal controls. The pre-ejection period was shortened 26 msec in normal subjects and 35 msec in angina patients. In normal subjects, total electromechanical systole corrected for heart rate (Q22c) decreased 24 msec, while the left ventricular ejection time corrected for heart rate (LVETc) remained unchanged. In the angina group, by contrast, Q22c failed to change, while LVETc lengthened 23 msec. The angina patients developed similar abnormalities, without pain, after 2 min of exercise. Changes in arterial pressure, cardiac output, and stroke volume failed to explain these systolic temporal abnormalities. Similar abnormalities occurred in 12 patients with primary myocardial disease and heart failure, but not in seven noncardiac patients with nonanginal chest pain. Owing to impaired left ventricular performance and increased afterload, mild exercise prolongs left ventricular ejection in patients with angina. This abnormal prolongation contributes to the development of angina and has value in its diagnosis.
Journal Article•
TL;DR: This chapter focuses on the existence of idiotypic determinants that are useful in pursuing investigations related to the structure and biosynthesis of antibodies.
Abstract: Publisher Summary This chapter focuses on the existence of idiotypic determinants that are useful in pursuing investigations related to the structure and biosynthesis of antibodies. As defined, idiotypy applies to determinants recognized by an antiserum prepared in the same species and the term, individually specific antigenic determinant, is generally used with reference to determinants defined by an antiserum prepared in a heterologous species, such as a rabbit antiserum directed to a purified human antibody or myeloma protein. The original definitions of idiotype and individually specific antigenic determinant do not specifically consider such cross-reactions. In estimation, the discovery of cross-reactions or identity among immunoglobulins from different donors would not compromise the usefulness of these terms and the definitions might be qualified accordingly. A contribution of the constant region to an individually specific determinant is possible, but individually specific differences among proteins must reflect differences in the variable regions. It may be noted that isotypic and allotypic antigenic determinants similarly reflect particular amino acid sequences, which in many instances have been defined.