cssi/SciSciGPT-SciSciNet huggingface dataset:
Extraordinary fossils reveal the nature of Cambrian life: a commentary on Whittington (1975) ‘The enigmatic animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Columbia’

Harry Whittington's 1975 monograph on Opabinia was the first to highlight how some of the Burgess Shale animals differ markedly from those that populate today's oceans. Categorized by Stephen J. Gould as a ‘weird wonder’ ( Wonderful life , 1989) Opabinia , together with other unusual Burgess Shale fossils, stimulated ongoing debates about the early evolution of the major animal groups and the nature of the Cambrian explosion. The subsequent discovery of a number of other exceptionally preserved fossil faunas of Cambrian and early Ordovician age has significantly augmented the information available on this critical interval in the history of life. Although Opabinia initially defied assignment to any group of modern animals, it is now interpreted as lying below anomalocaridids on the stem leading to the living arthropods. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society .
CO uptake kinetics of red cells and CO diffusing capacity.

Abstract The rate at which CO displaces oxygen from combination with hemoglobin in intact red cells was measured spectrophotometrically in whole blood thin films that minimize unstirred layer extra-cellular diffusion barriers. A step-change was made in CO tension from zero to one of four values (2, 7, 21 and 70 Torr) during a constant background of one of eight O2 tensions (0, 40, 70, 100, 153, 214, 285 and 428 Torr). For PO2 > 100 Torr measured red cell initial CO uptake rates were compared with calculated rates at the same PCO·PO2 based on the Gibson-Roughton rate equation (Gibson and Roughton, Proc. R. Soc. B 143: 310–334, 1955) for a well mixed Hb solution. Measured CO uptake rates expressed as initial rate of saturation change (ΔS/Δt) quantitatively followed the theoretical rate equation (time in seconds) 1 δ S δt = 0.025 + 0.0945· P O2 P CO These measurements provide new values for ΘCO, the specific conductance of whole blood (ml·min−1·Torr−1; PCO,PO2 in Torr): 1 ∅ = 0.00211 · P CO + 0.00787 · P O2 These results signify that in vivo, in normoxia and hyperoxia, red cell CO uptake rate is wholly reaction rate limited and that pulmonary capillary red cell CO diffusion equilibrium is rapidly achieved. The Bohr-Krogh assumption that red cell PCO = 0 during CO uptake is untrue.
Effect of material parameters on the erosion resistance of brittle materials

Erosion data are compared with two theories that have been suggested to explain the erosive behaviour of solids. A dimensional analysis is applied to the variables that are important to erosion, and a multivariate, linear regression analysis is used to fit the data to the dimensional analysis. The results of the linear regression analyses are compared with the two theories in order to evaluate the applicability of these theories to erosion. Although semi-quantitative agreement of the data with the theories is obtained, some discrepancies are apparent. In particular, the dependence of erosion rate on hardness and critical stress intensity factor is greater than predicted by either of the two theories. These discrepancies are attributed primarily to microstructural aspects of erosion that are not modelled by either of the theories.
Partial purification and further characterization of the triphosphopyridine nucleotide specific C19-17beta-hydroxysteroid dehydrogenase of guineapig liver.

The TPN-specific C19-17β-hydroxysteroid dehydrogenase of guinea-pig liver has been purified five-fold by precipitation with 50–60% (NH4)2SO4 saturation of a 105000 × g supernatant fraction followed by chromatography on diethylaminocellulose. A similar purification has been achieved by continuous paper electrophoresis of the 105000 × g supernatant. The enzyme migrates towards the negative electrode. The partially purified preparations dehydrogenated only the 17β-hydroxyl of a number of C19 steroids and was free of several other TPN-linked enzyme systems. It showed no requirement for metal ions.
Chromosomal uniformity in the avian subclass Carinatae

1. A method for making two-dimensional measurements of colchicinized metaphase chromosomes was applied to six avian species and one interfamilial hybrid of the subclass Carinatae: the canary (Serinus canarius, 2n=80±), the parakeet (Melopsittacus undulatus, 2n=58±), the pigeon (Columba livia domestica, 2n= 80±), the turkey-pheasant hybrid (♂ Meleagris gallopavo × ♀ Phasianus colchicus, 2n=80±), the Japanese quail (Coturnix coturnix japonica, 2n=78 ±), the jungle fowl of Java (Gallus gallus bankivo, 2n=78 ±), and the duck (Anas platyrhyncha domestica, 2n=80 ±). 2. In these species representing five different orders of diverse geographic origin, the total chromosome area varied only from 62.42 μ2 in the turkey-pheasant hybrid to 67.95 μ2 in the parakeet. 3. The absolute size of the Z-chromosome was equally uniform, ranging only from 2.3 μ2 in the pigeon and duck to 3.0 μ2 in the canary. A W-chromosome two-thirds as large as the Z was noted in the female canary and pigeon; thus the sex chromosome constitution of the heterogametic sex in all avian species is probably ZW, not ZO. 4. Class Aves, subclass Carinatae, constitutes an independently uniform class with regard to the total chromosome area and the absolute size of the Z-chromosome.
MODELING THE CONTROL OF ISOMETRIC FORCE PRODUCTION WITH PIECE-WISE LINEAR, STOCHASTIC MAPS OF MULTIPLE TIME-SCALES

In human movement, the large number of system degrees of freedom at different levels of analysis of the system, joints, muscles, motor units, cells etc, naturally affords complexity and adaptability in action. It also leads to variability in movement and its outcome, even in intentional efforts to reproduce the same movement or action goal. An example is continuous isometric force output to a constant force level where the amount and structure of force variability changes with information available, force level and individual differences. In this paper we model the control of isometric force production with piece-wise linear stochastic maps of multiple time scales. At the core of our model is a piecewise linear function, depending on three parameters that can be estimated from the observed data that is perturbed by additive Gaussian noise at a given level. The result of the stochastic forcing is that outside of a threshold interval the system behaves like a discrete Ornstein-Uhlenbeck process and inside it performs a Brownian motion. The model is shown to simulate the basic findings of the structure of human force variability that decreasing variability is correlated with increased dynamical complexity as measured with the "Approximate Entropy (ApEn)" statistic.
Stochastic response analysis, order reduction, and output feedback controllers for flexible spacecraft

Real disturbances and real sensors have finite bandwidths. The first objective of this paper is to incorporate this finiteness in the 'open-loop modal cost analysis' as applied to a flexible spacecraft. Analysis based on residue calculus shows that among other factors, significance of a mode depends on the power spectral density of disturbances and the response spectral density of sensors at the modal frequency. The second objective of this article is to compare performances of an optimal and a suboptimal output feedback controller, the latter based on 'minimum error excitation' of Kosut. Both the performances are found to be nearly the same, leading us to favor the latter technique because it entails only linear computations. Our final objective is to detect an instability due to truncated modes by representing them as a multiplicative and an additive perturbation in a nominal transfer function. In an example problem it is found that this procedure leads to a narrow range of permissible controller gains, and that it labels a wrong mode as a cause of instability. A free beam is used to illustrate the analysis in this work.
The Value of Chest Roentgenograms in Acute Asthma in Adults

Chest roentgenograms were obtained in 90 episodes of acute asthma in adults coming to an emergency room. Of these 90 roentgenograms, 50 (55 percent) were interpreted as normal, 33 (37 percent) showed hyperinflation, and 6 (7 percent) showed minimal interstitial abnormalities unchanged from previous roentgenograms. One (1 percent) showed a new alveolar infiltrate in a patient with allergic aspergillosis. There was no significant correlation between chest roentgenogram interpretation and hospitalization. Our data show that the incidence of specific abnormalities on chest roentgenogram in adults with uncomplicated acute asthma is low and suggests that the information obtained from the roentgenogram is rarely helpful to outpatient management. Chest roentgenograms probably are indicated only when there is clinical evidence of pneumonia, a complication of asthma, or a pulmonary disorder that mimics asthma.
The ultrastructure of the adenomatoid odontogenic tumor

An adenomatoid odontogenic tumor (AOT) which occurred in the maxilla of an 8-year-old boy was studied by the light and electron microscopy. The tumor was found to contain cells resembling preameloblasts, the stratum intermedium, and the stellate reticulum, suggesting its origin from the enamel organ, in agreement with previous reports. Characteristic ductlike structures are thought to be formed as a result of secretory activity of the tumor cells, rather than degeneration. Duct-lining cells ultrastructurally similar to preameloblasts were found to contain electron-dense granules. These granules are believed to play a role in secretion by tumor cells, a concept not previously considered. The results of previous ultrastructural studies of the AOT are reviewed and summarized.
Stochastic dominance in mobility analysis

Abstract This paper introduces a technique for mobility dominance and compares the degree of earnings mobility of men in the USA from 1970 to 1995. The highest mobility is found in the 1975–1980 or 1980–1985 periods.
Racial and Ethnic Differences in Secular Trends for Childhood BMI, Weight, and Height

Objectives: The prevalence of childhood overweight in the United States has markedly increased over the last 30 years. We examined differences in the secular trends for BMI, weight, and height among white, black, and Mexican-American children. Research Methods and Procedures: Analyses were based on nationally representative data collected from 2 to 17 year olds in four examinations (1971–1974 through 1999–2002). Results: Overall, black children experienced much larger secular increases in BMI, weight, and height than did white children. For example, over the 30-year period, the prevalence of overweight increased ∼3-fold (4% to 13%) among 6- to 11-year-old white children but 5-fold (4% to 20%) among black children. In most sex-age groups, Mexican-American children experienced increases in BMI and overweight that were between those experienced by blacks and whites. Race/ethnicity differences were less marked among 2 to 5 year olds, and in this age group, white children experienced the largest increase in overweight (from 4% to 9%). In 1999–2002, the prevalence of extreme BMI levels (≥99th percentile) reached 6% to 7% among black girls and Mexican-American boys. Discussion: Because of the strong tracking of childhood BMI levels into adulthood, it is likely that the secular increases in childhood overweight will greatly increase the burden of adult disease. The further development of obesity interventions in different racial/ethnic groups should be emphasized.
Topical formulations of metaflumizone plus amitraz to treat flea and tick infestations on dogs

A topical spot-on solution was developed for treating pets that contained of active ingredients metaflumizone and amitraz and intended for use as an ectoparasiticide. The formulation vehicle system was designed by balancing the following three attributes of various solvents: evaporation/drying, surface spreading, and percutaneous absorption. The solvents were selected by evaluating the solubilization capacity of individual solvents with respect to the above active ingredients. The evaporation rates of various solvent systems were then determined. The visual observations of the treatment sites was also performed a day after treating the dogs to understand the cosmetic effect of various solvent systems. The lead formulations dried off within a day after application with no noticeable residue at the treatment site, while others produced appreciable powdery residue or a large wet and oily spot. The stability of the lead formulations was also evaluated over 2 years to demonstrate a 2-year shelf life of this product.
APC and intestinal carcinogenesis. Insights from animal models.

The APC protein is a crucial regulator of intestinal cell growth, and mutations in the APC gene are a common initial event in the process of human colorectal carcinogenesis. animals bearing germline mutations in Apc are therefore important models for human colorectal cancer. these animals have been used both to understand the biology of human colorectal cancer and to screen for agents able to prevent malignant transformation of susceptible intestinal cells.
A multiminiprocessor system implemented through pipelining

Several recent and proposed computer systems have employed parallel and pipelined architectures to increase instruction execution rate, or throughput. These vary from the giant ILLIAC IV1 with its large number of processing elements constrained to perform nearly identical computations in unison (single instruction stream-multiple data stream9) to the Carnegie-Mellon C. mmp system2 employing a number of independent minicomputers with shared memory (multiple instruction stream-multiple data stream). On the other hand, pipelining has been used in numerous' large computers, such as the Control Data 6600, 7600, and STAR, the IBM System 360/91 and 360/195, and the Texas Instruments ASC, to improve throughput. These systems generally employ single instruction stream-single data stream processing, although some machines in this category also have “vector” instructions that operate on multiple data streams.
Carbohydrate metabolism in transforming lymphocytes from the aged

There is an age-related decline in immune capacity which has been linked to a decreased response of lymphocytes to mitogens in vitro. During transformation, lymphocytes require a marked increase in energy production and biosynthesis which is supplied primarily by glycolysis. In the elderly, the glycolytic enzymes increase significantly in transforming lymphocytes at least 24 hr later than in the young and then at significantly reduced levels. Glucose utilization is also impaired in stimulated lymphocytes from the elderly but follows the impairment of glycolysis. In stimulated cells from the young, increases in glycolytic enzyme activity levels accompany sharp increases in blastogenesis while a delayed increase in glycolytic enzyme activity in the elderly is accompanied by a delay in blastogenesis. Maximal glycolytic enzyme activity levels are significantly reduced in transformed lymphocytes from the elderly though the number of transformed cells is also significantly reduced. However, glycolytic enzyme activity levels are significantly lower in the elderly than in the young even on a per transformed cell basis. Thus, this reduction cannot be attributed to the lower number of transformed cells that are present in the elderly. This defect in the increase of glycolysis in stimulated cells from the elderly suggests an intracellular mechanism which could be related to the impaired lymphocyte stimulation in vitro in the aged.
Lower thoracic upper lumbar spinocerebellar projections in rats: a complex topography revealed in computer reconstructions of the unfolded anterior lobe.

Abstract The topography of wheatgerm agglutinin-horseradish peroxidase/horseradish peroxidase-labeled mossy fiber terminals of lower thoracic-upper lumbar (T 12 -L 3 ) spinal projections to the cerebellar anterior lobe was quantitatively analysed in adult rats. Computer-based image analysis mapped the orthogonal (parallel to the surface) distribution of labeled terminals in two-dimensional reconstructions of the unfolded anterior lobe cortex. The radial (perpendicular to the surface) distribution of terminals within the granule cell layer was mapped by computing whether the terminals were in either the outeror inner-halves of this layer. The number of labeled terminals in each lobule was calculated. In the anterior lobe, lower thoracic-upper lumbar spinocerebellar projections terminate primarily in lobules II (mean 27.14%), III (mean 38.68%), and IV (mean 19.31%). Different-sized bilateral injections restricted to L 1 were used to study the organization of intrasegmental spinocerebellar projections. Small injections into L 1 labeled a limited number of terminals which were located either in clusters or were spatially isolated. Intermediate-sized intrasegmental injections resulted in additional clusters of labeled terminals. Many of the terminal clusters were spatially related and formed larger irregularly shaped patches. Large intrasegmental injections labeled terminal clusters and patches that were discontinuous but aligned parallel to the longitudinal (transverse) axis of lobules II–IV. Injections including segments rostral and caudal to L 1 were used to study the topography of intersegmental lower thoracic-upper lumbar spinocerebellar projections. Multisegmental injections increased the number of labeled terminal clusters and patches which obscured the pattern of segmental input, but there was still a transversely oriented pattern of termination. Distinct transversely aligned terminal free areas remained apparent. Lower thoracic-upper lumbar spinocerebellar projections terminated in both the outer- and inner-halves of the granule cell layer, but overall were more numerous in the outer-half of this layer. In serially spaced sagittal sections, however, the majority of terminals alternated between the outer- and inner-halves of the granule cell layer. Outer-and inner-terminals were not spatially segregated in their orthogonal distribution. These results indicate lower thoracic-upper lumbar spinocerebellar projections have a complex three-dimensional topography in the anterior lobe. These findings are discussed in relation to previous findings for a sagittally oriented topography for lower thoracic-upper lumbar spinocerebellar projections and in the context of how cerebellar somatosensory afferent input may be organized.
Forced mixing in boundary layers

The effect of increasing the rate of mixing in turbulent boundary layers in a region of adverse pressure gradient has been investigated experimentally. Only the two-dimensional case was considered. The boundary layer was formed on a flat wall in a special wind tunnel in which a variety of adverse pressure gradients could be obtained. Speeds were low enough to justify the neglect of compressibility. The main objective was to compare the effect of increasing the rate of mixing with the effect of reducing the pressure gradient on boundary-layer development and separation. A Variety of mixing schemes was tried, all of them involving fixed devices arranged in a row on the surface in the region of rising pressure. While these differed considerably in effectiveness, they had a generally similar effect on the flow; and, except for effects arising from changes in displacement and momentum thickness introduced at the devices, their effect on the layer was basically equivalent to that of a decrease in pressure gradient. Apart from forced mixing, the shape of the pressure distribution was found to have a significant effect on displacement and momentum thickness, these being minimized and the wall distance decreased for a given pressure rise by a distribution with an initially steep and progressively decreasing gradient.
APPGEN: a tool for teaching systems analysis and design

APPGEN is a program which generates information systems. It is easy to use and powerful and runs on a VAX under VMS. It has been used with success in senior level courses on systems analysis and design. Using APPGEN, students are able to analyze and design systems of realistic size and still have time to implement them. Implementations give students important feedback about their designs and give additional focus to a class on systems analysis and design. Students get satisfaction from actually creating a working system.
Assessment of Folsom Lake response to historical and potential future climate scenarios: 2. Reservoir management

An integrated forecast–decision system for Folsom Lake (California) is developed and used to assess the sensitivity of reservoir performance to various forecast–management schemes under historical and future climate scenarios. The assessments are based on various combinations of inflow forecasting models, decision rules, and climate scenarios. The inflow forecasting options include operational forecasts, historical analog ensemble forecasts, hydrologic ensemble forecasts, GCM-conditioned hydrologic ensemble forecasts, and perfect forecasts. Reservoir management is based on either heuristic rule curves or a decision system which includes three coupled models pertinent to turbine load dispatching, short-range energy generation scheduling, and long/mid-range reservoir management. The climate scenarios are based on historical inflow realizations, potential inflow realizations generated by General Circulation Models assuming no CO2 increase, and potential inflow realizations assuming 1% CO2 annual increase. The study demonstrates that (1) reliable inflow forecasts and adaptive decision systems can substantially benefit reservoir performance and (2) dynamic operational procedures can be effective climate change coping strategies.
Postischemic recovery in the stunned myocardium after reperfusion in the presence or absence of a flow-limiting coronary artery stenosis.

Abstract Hyperemic flow occurs after release of a transient coronary artery occlusion in excess of the acquired oxygen debt if the vessel has sufficient vasodilator reserve. The purpose of this study was to determine whether differences exist in the degree of postischemic functional and metabolic recovery in the stunned myocardium when a reactive hyperemia is allowed to occur as opposed to reperfusion in the presence of a flow-limiting coronary artery stenosis. Anesthetized dogs were subjected to 15-minute episodes of coronary artery occlusion, followed by either 10 minutes (short reperfusion) or 3 hours (long reperfusion) of reperfusion to investigate early and late differences in tissue blood flow. At reperfusion a micrometer-driven occluder was either released fully within 1 minute (full-reactive [FR] group) or the occluder was slowly released to return coronary blood flow to preocclusion levels (no-reactive [NR] group). Areas at risk, myocardial blood flow (radioactive microspheres), hemodynamics, myocardial segment shortening (sonomicrometry) during occlusion, and high-energy phosphate levels (tissue biopsies) at 3 hours of reperfusion were similar in both groups. Recovery of function in the short-reperfusion group was significantly greater in the FR than the NR group until 3 minutes of reperfusion, which corresponded to the peak reactive hyperemic response. After this time there were no differences between the two groups in functional recovery until 2 and 3 hours after reperfusion when the percentage of segment shortening had deterlorated to a significantly greater extent ( p
Beyond symbiosis: The humanist, the librarian, and the computer

s and tables of contents. In this way, works relating to his interest, but not listed in bibliographies of his own discipline, could also be located. A thesaurus would be provided, to suggest alternative subject descriptions. Most important,the researcher's method of search and selection would be
Esophageal rupture: diagnosis by pleural fluid pH.

Failure to appreciate the significance of a pleural fluid pH of 5 led to delay in establishing a diagnosis of esophageal rupture. In a subsequent study the pH of 56 pleural fluid specimens from 50 patients with conditions other than esophageal rupture was determined. In no case was the pH less than 6. While a pleural fluid pH of 6 or greater may be associated with a variety of conditions, a value less than 6 is highly suggestive of esophageal rupture.
Sorbinil does not prevent galactose-induced glomerular capillary basement membrane thickening in the rat.

We investigated the role of the polyol pathway in the pathogenesis of glomerular basement membrane thickening in galactosaemic rats, an animal model that develops basement membrane lesions comparable to those of human diabetic subjects. Normotensive Wistar-Kyoto rats fed a 30% galactose diet for nine months developed significant glomerular basement membrane thickening by comparison with rats on a control test diet (p=0.008). However, addition of an aldose reductase inhibitor, sorbinil (250 mg/kg diet), to the galactose diet did not prevent the increase in glomerular basement membrane thickness. Furthermore, by using a quantitative electron microscopic immunogold technique, we examined biochemical alterations in the composition of glomerular basement membranes in this animal model. The labelling density (comparable to relative concentration) of collagen type IV in thickened glomerular basement membranes of galactosaemic animals was significantly increased by comparison to those of control rats (p=0.015). However, there was no significant difference in labelling densities of laminin and heparan sulfate proteoglycan core protein of these animals. Thus, our results indicate that an increase in glomerular basement membrane thickness accompanied by an increase in the labelling density of collagen type IV occurs in the galactosaemic rats, but this thickening is not prevented by sorbinil at the dose used in this experiment. Our study raises the strong possibility that glomerular basement membrane thickening in galactosaemic rats may not be due to excessive polyol pathway activity.
Self-aligned double patterning layout decomposition with complementary e-beam lithography

Advanced lithography techniques enable higher pattern resolution; however, techniques such as extreme ultraviolet lithography and e-beam lithography (EBL) are not yet ready for high volume production. Recently, complementary lithography has become promising, which allows two different lithography processes work together to achieve high quality layout patterns while not increasing much manufacturing cost. In this paper, we present a new layout decomposition framework for self-aligned double patterning and complementary EBL, which considers overlay minimization and EBL throughput optimization simultaneously. We perform conflict elimination by merge-and-cut technique and formulate it as a matching-based problem. The results show that our approach is fast and effective, where all conflicts are solved with minimal overlay error and e-beam utilization.
Single-Pair versus Multiple-Pair Answers: Wh -in-Situ and Scope

It is a well-accepted generalization that wh-in-situ can take unbounded scope. This squibe examines the diagnostic of paired answers on which this generalization is based and argues that a more refined understanding of the diagnostic leads to a reassessment of the claims about in-situ and scope
Assessing cognitive functioning of the elderly with the ‘Inventory of Piaget's Developmental Tasks’

The purpose of this study was to examine the reliability, validity, and utility of the 'Inventory of Piaget's Developmental Tasks' (IPDT) with elderly persons. The IPDT is a paper-pencil assessment of levels of cognitive functioning. Seventy elderly adults responded to a battery of instruments. Reliability and validity estimates for the IPDT were acceptable. Data indicated that the IPDT has promise as a clinical assessment of cognitive functioning. Implications for patient teaching by nurses is discussed and suggestions for clinical use are made.
Structural and conceptual interweaving of mathematics methods coursework and field practica

This paper describes a study of observed relationships between the design of a preservice elementary mathematics methods course with accompanying field practicum and changes in the extent to which participating prospective teachers identified themselves with the mathematics reform movement after becoming practicing teachers. The curriculum of the course with its embedded field practicum experiences was designed to support prospective teachers in interweaving methods coursework and pedagogical instruction with classroom practice. University and elementary school structures were interwoven by conducting weekly mathematics methods course sessions at a school site followed immediately by related practicum experiences in classrooms in the school. The interweaving of conceptualizations about mathematics teaching and learning was facilitated as the methods instructor provided professional development for classroom teachers simultaneously with the methods course, encouraging the teachers to create “reform-friendly” classroom environments. Survey data from 68 prospective teachers involved in the project were analyzed to identify and describe relationships between course/practicum experiences and the degree to which they as practicing teachers, 1–3 years following the course/practicum, identified with a reform mathematics perspective, as well as to examine factors influencing those relationships.
The effect of dietary o,p'-DDT on ureagenesis from ammonia by isolated rat hepatocytes.

Abstract Hepatocytes isolated from rats which had been fed 1000 ppm o,p′ -DDT for 2 weeks and starved for 48 hr exhibited markedly reduced rates of urea synthesis and citrulline accumulation when incubated with 10 m m NH 4 Cl and 10 m m ornithine. The addition of 10 m m lactate to such incubations stimulated the rate of ureagenesis by both control and DDT-treated cells to nearly the same degree but did not eliminate the difference in rates of urea synthesis between control and DDT-treated cells. The activities of carbamoylphosphate synthase, ornithine carbamoyltransferase, arginine synthetase, and arginase were similar in livers from control and DDT-treated rats. The kinetics of the stimulation of urea synthesis by exogenous ornithine were similar with hepatocytes from both control and DDT-treated rats. Mitochondria isolated from the livers of control and DDT-treated rats exhibited similar rates of citrulline synthesis from ammonia and ornithine as well as similar responses to N -acetylglutamate and 2,4-dinitrophenol. These results suggest that DDT treatment may produce alterations in the kinetic behavior of urea cycle enzymes which are not detected in the standard assays of these enzymes or DDT treatment may interfere with the intermitochondrial transport processes required during ureagenesis from ammonia.
Abnormal frequency-dependent responses represent the pathophysiologic signature of contractile failure in human myocardium.

Abstract Background. – The normal increase in isometric developed force (DF) with faster pacing rates, known as the positive force–frequency response/relationship (FFR), is altered in failing myocardium, as shown by its negative response to increased pacing. The objective of this study was to determine if increasing Ca 2+ influx with L-type Ca 2+ channel (L-CaCh) agonists: BayK 8644 (BayK) and FPL 64176 (FPL) or increased extracellular Ca 2+ could increase contractility and normalize the FFR in failing myocardium. Methods. – Isometric DF was measured in right ventricular trabeculae from failing ( n = 28) and non-failing ( n = 12) human hearts at various stimulation frequencies (0.5–2.5 Hz) before and after bath application of BayK (250 nM), FPL (100 nM), or high Ca 2+ (7.0 mM). Post-rest (PR) experiments were also conducted on several trabeculae. Results. – In trabeculae from failing hearts, the DF decreased with an increase in pacing. Addition of L-CaCh agonists increased DF to similar levels in trabeculae from both failing and non-failing hearts at slow pacing rates, but did not alter the negative FFR in the failing group. During increased rest intervals, the amount of PR potentiation was diminished in trabeculae from failing hearts as compared to the non-failing preparations. Conclusion. – This study demonstrates that the abnormal FFR observed in trabeculae from failing hearts is a reliable physiologic signature of the cardiomyopathic state even when DF, at slow stimulation frequencies, is relatively high. These studies further demonstrate that the impaired FFR is not due to an inability to further increase contractility. Rather, our findings suggest that the abnormal FFR and blunted PR potentiation alike are a reflection of an altered functional balance between Ca 2+ re-uptake and Ca 2+ extrusion.
Performance-based seismic design of unbonded precast post-tensioned concrete filled GFRP tube piers

This paper presents a seismic design procedure for self-centering precast post-tensioned bridge piers. The piers presented in this manuscript consisted of concrete filled fiber reinforced polymer (FRP) tubes. A large set of 84 piers with different design parameters were analyzed using finite element models. The backbone curve of each pier was developed and bilinearized. The idealized backbone curves were used to develop a set of empirical equations that were able to reproduce the bilinearized backbone curve of a given pier. Different performance criteria have been proposed for the system according to the intensity and the frequency of occurrence of a seismic event. The developed empirical equations were arranged in a design procedure to achieve a given performance level at a specific seismic zone.
Studies on the mechanism by which phytohemagglutinin rapidly stimulates phospholipid metabolism of human lymphocytes

The growth initiator phytohemagglutinin rapidly accelerates 32Pi incorporation into lymphocyte phosphatidylinositol. This study shows that phytohemagglutinin rapidly accelerates myo-[2-3H]inositol incorporation (1800%) but only slightly increases [2-3H]glycerol and inhibits [1-14C]oleic acid incorporation into phosphatidylinositol. A convenient method for isolating the lymphocyte plasma membrane and nuclear fractions is described. 3 min exposure of lymphocytes to phytohemagglutinin produces a 430% stimulation of 32Pi incorporation into phosphatidic acid of the plasma membrane fraction while in the nuclear fraction the stimulation is only 80%. Under these conditions, 32Pi incorporation into phosphatidylinositol is stimulated to nearly the same extent in all fractions. Direct addition of phytohemagglutinin to a lymphocyte plasma membrane fraction stimulates phosphatidic acid synthesis by diglyceride kinase. It is suggested that phytohemagglutinin stimulates the cyclic interconversion of phosphatidic acid and phosphatidylinositol.
Longitudinal evaluation of dose-response relationships for environmental exposures and pulmonary function in swine production workers.

Studies describing respiratory health hazards for workers in swine production facilities have been published in the United States, Sweden, Canada, the Netherlands, and Denmark. Up to 50% of these workers experience bronchitis, organic dust toxic syndrome, hyper-reactive airways disease, chronic mucous membrane irritation, and other respiratory effects. These studies clearly point to the fact that this occupational environment poses a significant health risk hazard, and that control methods are needed to protect the worker. Before precise control strategies can be developed, implemented, and evaluated, dose-response studies are required to determine acceptable target levels for exposure. A previous manuscript described the development of multiple regression equations characterizing the relationships between environmental exposures and pulmonary response in a cohort of 207 swine producers. Baseline pulmonary function was included as a significant predictor of cross-shift decrements in pulmonary function in addition to personal measurements of dust, endotoxin, and ammonia concentrations. These equations were then used to predict specific exposure levels of dust and ammonia that could be expected to elicit significant decrements in cross-shift pulmonary function. This paper presents the results from analysis of follow-up data obtained on this same cohort 2 years after the initial measurements. At the second measurement period of the study (time-2), swine workers were found to have a mean cross-shift decrease in FEV1 of 2%. Cross-shift change in FEV1 was significantly correlated with personal exposures to total dust, total endotoxin, respirable endotoxin, and ammonia The magnitude of the decrease in FEV1 was associated with increasing airborne concentrations of these environmental parameters thus confirming the dose-response relationship observed in the initial study (time-1). The correlation of dust with FEV1 changes in workers with more than 6 years of exposure (time-1 data) and more than 10 years of exposure (time-2 data) suggests that dust exposure is an important factor in chronic respiratory disease. Additionally, the correlation of endotoxins with FEV1 changes in the group with less than 6 years exposure (time-2 data) suggests endotoxins may have more significance for subacute respiratory effects. The agreement between observed cross-shift FEV1 changes measured in time-2 with changes predicted using regression equations derived front time-1 data demonstrates a consistent dose-response relationship over time for this cohort of swine production workers. This finding provides further support for conclusions of the previous study that levels of 2.5 mg/m3 (total dust) and 7.5 ppm (ammonia) are reasonable guidelines for occupational exposure limits in this environment. © 1996 Wiley-Liss, Inc.
An experimental facility for measurement of charged particle continua arising from neutron induced reactions

Abstract A facility to measure neutron-induced charged-particle continua using beams of 25–60 MeV is described. The heart of the facility consists of the production and collimation of a neutron beam into a scattering chamber containing the target and three independent detector telescopes. Each telescope contains three elements and provides good particle identification for p, d, t, 3 He, and α. While “ E - δE ” displays are used to identify energetic particles, a time-of-flight versus pulse-height scheme is used to identify low-energy alphas (from 3–8 MeV) that stop in the first element. Good timing and energy resolution obtained with this system allow the simultaneous measurement of hydrogen and helium isotopes with a wide range of energies: from about 3–60 MeV. Corrections to measured spectra relevant to this set-up are discussed. This facility has been used to obtain extensive data on neutron-induced reactions on tissue-resident elements such as carbon, nitrogen and oxygen.
Unpredictable saccharin reinforcement enhances locomotor responding to amphetamine

Drug-naive, non-deprived rats were trained to lever press for saccharin under fixed-ratio (FR) or variable-ratio (VR) schedules of reinforcement. Rats trained on the VR schedule in which saccharin reinforcement was not predicted by a fixed number of lever presses subsequently showed an enhanced locomotor response to a threshold amphetamine challenge injection (0.5 mg/kg IP) administered 2 weeks following the last saccharin session. This finding suggests that chronic exposure to gambling-like conditions of uncertain reinforcement can induce neuroadaptations in brain reward systems that are similar to those produced by repeated psychostimulant exposure and may lead to the development of addictive behaviors.
6-Alkyl-1,3,8-trichlorodibenzofurans as antiestrogens in female Sprague-Dawley rats.

Abstract The comparative antiestrogenic effects of 6-methyl-1,3,8-trichlorodibenzofuran (MCDF), 6- t -butyl-1,3,8-trichlorodibenzofuran (triCDF) and 6-cyclohexyl-1,3,8-triCDF were determined in immature female Sprague-Dawley rats. Treatment of the animals with 17β-estradiol (0.33 μmol/kg × 2) caused an increase in uterine cytosolic and nuclear estrogen and progesterone receptor levels, uterine peroxidase activity, uterine wet weights and uterine epidermal growth factor (EGF) receptor binding activity and steady state EGF receptor mRNA levels. MCDF and 6- t -butyl-1,3,8-triCDF, two compounds which exhibit moderate aryl hydrocarbon (Ah) receptor binding affinity were also administered (100 μmol/kg) to the female rats in the presence or absence of 17β-estradiol. The results of these studies show that both compounds decrease the constitutive and 17β-estradiol-induced responses noted above. In contrast, 6-cyclohexyl-1,3,8-triCDF, a congener which exhibits low Ah receptor binding, was inactive as an antiestrogen. These studies clearly demonstrate that selected 6-alkyl-1,3,8-triCDFs elicit a broad spectrum of antiestrogenic activity in immature female rats. Moreover, in contrast to 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) which also is a potent antiestrogen, the 6-alkyl-1,3,8-triCDFs are relatively non-toxic and can serve as prototypes for the future development of a new class of antiestrogens with potential for clinical applications.
Selenium and cancer: Chemical interpretation of a plasma “cancer test”

Abstract The Methylene Blue Reduction Time (MBRT) of human plasma, introduced in 1947 as a chemical test for malignancy, was later found to be insufficiently specific or accurate for routine cancer diagnosis. However, the MBRT of human plasma samples is inversely related to the total plasma selenium content ( r = −0.56; P = 0.002). The MBRT is also inversely related to plasma pH, but is insignificantly affected by observed variations in plasma sulfhydryl, copper, iron, and cobalt levels ( P = 0.05). The diminished plasma selenium levels observed in malignant disease support the suggestion that selenium is a cancer protecting agent; statistical analysis demonstrates that those states of the United States with elevated selenium levels in forage crops and grains have lowered cancer mortality ( r = −0.467; P = 0.01). These results are supported by statistical data and animal carcinogenesis experiments of other investigators.
Finite element model of the cyclic bending behavior of hollow structural sections

Abstract Hollow structural sections (HSS) are desirable for utilization in structural applications due to their inherent flexural, compression, and torsional properties. These sections are highly efficient, but have been underutilized in cyclic bending applications due to a lack of understanding of their behavior under these loads. To address the limited experimental data and determine potential limiting parameters for the use of HSS in seismic bending applications, a finite element model (FEM) considering experimentally measured material properties, section geometry, and geometric imperfections has been calibrated and validated to experimental findings. A parametric study is conducted on 133 different standard HSS beam members of sizes ranging from HSS 152 × 50.8 × 4.8 to HSS 508 × 305 × 15.9. To provide insight into the parameters that limit stable hysteretic behavior, the decrease in the overall maximum moment capacity with cycling at a given rotation level, rotational capacity at a given degradation of the moment capacity, and decrease of the secant stiffness with cycling are considered. The findings provide information about the interdependence of the width–thickness and depth–thickness ratios on the cyclic bending behavior of HSS. Linear regression analyses provide a relationship between the width–thickness and depth–thickness ratios and member performance from which equations for predicting the degradation of moment capacity and rotational capacity can be defined.
Rat proximal small intestinal Golgi membranes: lipid composition and fluidity

The present studies were conducted to examine and characterize the lipid composition and physical state of the membrane lipids of rat proximal small intestinal Golgi membranes. Golgi membranes were purified from isolated enterocytes; lipids were extracted from these membranes and analyzed by thin-layer and gas-liquid chromatography. The 'static' and 'dynamic' components of fluidity of Golgi membranes and their liposomes were assessed by steady-state fluorescence polarization techniques utilizing r infinity and S values of 1,6-diphenyl-1,3,5-hexatriene and r values of DL-2-(9-anthroyl)- and DL-12-(9-anthroyl)stearic acid, respectively. Additional studies were also performed on these membranes, using benzyl and methyl alcohol, to examine the relationship between alterations in lipid fluidity and glycosphingolipid glycosyltransferase activities. The results of these studies demonstrated that: (1) the principal phospholipids and neutral lipids of intestinal Golgi membranes, respectively, were phosphatidylcholine, phosphatidylethanolamine and sphingomyelin, and unesterified cholesterol and fatty acids; (2) the major fatty acids of Golgi membranes were palmitic (16:0), stearic (18:0), linoleic (18:2), arachidonic (20:4) and oleic (18:1) acids; (3) fluorescence polarization studies using diphenylhexatriene detected a thermotropic transition at 24-26 degrees C in Golgi membranes and liposomes prepared from lipid extracts of these membranes; (4) benzyl alcohol (25 and 50 mM) but not methyl alcohol (50 mM) significantly increased the fluidity of these membranes; and (5) at these same concentrations, benzyl alcohol was also found to increase significantly the specific activity of UDP-galactosyllactosylceramide galactosyltransferase but not CMP-acetylneuraminic acid: lactosylceramide sialyltransferase. Methyl alcohol was not found to influence either enzyme's activity in these membranes.
The utility of pretreatment barium enema in women with endometrial carcinoma.

Abstract Objective. The objective of this study was to assess the clinical utility of a pretreatment barium enema in women with endometrial cancer. Methods. The medical records of 249 patients with endometrial cancer who underwent a pretreatment barium enema were retrospectively reviewed. The patients' charts were abstracted for demographic information, stage, grade, histology, current disease status, and barium enema results. Results. The pretreatment barium enema was normal in 122 (49%) patients. Diverticulosis was the most common abnormality, reported in 112 (45%) patients. Apparent intraluminal abnormalities were found in 15 (6.0%) patients. Each of these patients underwent colonoscopy prior to treatment for endometrial carcinoma. During colonoscopy, benign colonic polyps were removed from 11 (4.4%) patients. Primary colonic adenocarcinoma was discovered in polypoid lesions removed from 2 (0.8%) patients. Significant luminal narrowing from extrinsic lesions was noted in 2 (0.8%) patients, one at the rectosigmoid and the other at the cecum. No patient was found to have colonic mucosal involvement by endometrial cancer. Conclusion. The results of this study do not justify routine pretreatment barium enema to assess the colonic mucosa for metastatic involvement by endometrial cancer or as a screening tool for colorectal cancer in women with endometrial cancer.