cssi/SciSciGPT-SciSciNet huggingface dataset:
Effects of thromboxane synthase inhibitors on renal function

In general the effects of thromboxane A2(TXA2) on renal function are opposite those produced by other prostanoids. TXA2 synthase inhibitors decrease the biosynthesis of TXA2 and may increase the production of other prostanoids by causing endoperoxide shunting. Therefore, in situations of increased kidney arachidonate mobilization, inhibition of renal TXA2 synthase might alter renal function by reducing TXA2 production and/or increasing prostaglandin (PG) biosynthesis. This hypothesis was tested by comparing the changes in renal function induced by suprarenal aortic constriction in anesthetized dogs pretreated with either a TXA2 synthase inhibitor (UK 38,485; n = 7 or OKY1581; n = 7) or vehicle (0.1 M Na2CO3; n = 9). Several renal function parameters were compared in control versus treated animals by analysis of variance. Neither UK38,485 (1 mg/kg, i. v.) nor OKY 1581 (10 mg/kg, i. v.) significantly altered renal artery hypotension-induced changes in mean arterial blood pressure, heart rate, renal blood flow, renal vascular resistance, glomerular filtration, filtration fraction, urine flow rate, sodium excretion rate, fractional sodium excretion, potassium excretion, or fractional potassium excretion. However, both UK 38,485 and OKY 1581 seemed to attenuate the increase in renal renin secretion rate induced by suprarenal aortic constriction. We conclude that acute administration of TXA2 synthase inhibitors does not modify acute renal artery hypotension-induced changes in either electrolyte excretion or renal hemodynamics. However, acute administration of TXA2 inhibitors attenuates suprarenal aortic constriction-induced increases in renin release in anesthetized dogs by unknown mechanisms.
(+)-Sorangicin A: evolution of a viable synthetic strategy

An effective, asymmetric total synthesis of the antibiotic (+)-sorangicin A (1) has been achieved. Central to this venture was the development of first and second generation syntheses of the signature dioxabicyclo[3.2.1]octane core, the first featuring chemo- and stereoselective epoxide ring openings facilitated by a Co(2)(CO)(6)-alkyne complex, the second involving a KHMDS-promoted epoxide ring formation/opening cascade. Additional highlights include effective construction of the dihydro- and tetrahydropyran ring systems, respectively via a stereoselective conjugate addition/α-oxygenation protocol and a thioketalization/hydrostannane reduction sequence. Late-stage achievements entailed two Julia-Kocienski olefinations to unite three advanced fragments with high E-stereoselectivity, followed by a modified Stille protocol to introduce the Z,Z,E trienoate moiety, thereby completing the carbon skeleton. Mukaiyama macrolactonization, followed by carefully orchestrated Lewis and protic acid-promoted deprotections that suppressed isomerization and/or destruction of the sensitive (Z,Z,E)-trienoate linkage completed the first, and to date only, total synthesis of (+)-sorangicin A (1).
Spectroscopy and Electrochemistry of mer-[RuCl3(dmso)(tmen)]. Dimethylsulfoxide Is Sulfur-Bonded to Ru(II), Ru(III), and Ru(IV)

The discovery that halo−ruthenium(sulfoxide) complexes exhibit anticancer activity has stimulated interest in the nature of bonding of metal ions to dimethylsulfoxide (dmso). Both M−S and M−O bonds are observed in metal complexes containing dmso, with the former mode prevalent with “soft” metal centers. The importance of dπ-S back-bonding in S-bonded complexes has been addressed by several investigators. Especially revealing was the finding by Taube and co-workers that S to O linkage isomerism can be induced by oxidation of pentaammineruthenium(II) to ruthenium(III), thereby suggesting that dπ-S bonding is a stabilizing factor only in the lower oxidation state. However, the observation that other Ru(III)(chloro)(dmso) complexes are S-bonded led Alessio and Calligaris to propose a role for dπ-S bonding in Ru(III) as well. In the course of our work on a related complex, mer-[RuCl_3(dmso)(tmen)] (dmso is dimethylsulfoxide; tmen is N,N,N‘,N‘-tetramethylethylenediamine), we have found that dmso also can be S-bonded to Ru(IV). Our findings suggest that S(dmso) σ-donation to Ru is extensive in the Ru(III) and Ru(IV) states.
Role of interleukin-6 in ß2-microglobulin–induced bone mineral dissolution

Role of interleukin-6 in s 2 -microglobulin–induced bone mineral dissolution. Background β 2 -microglobulin (β 2 m) amyloidosis is commonly seen in patients undergoing long-term dialysis. s 2 m has been shown to induce in vitro bone mineral dissolution. The present study was designed to investigate the effect of s 2 m on osteoblast function and the role of interleukin-6 (IL-6) on s 2 m-induced bone resorption. Methods Using neonatal mouse calvariae as well as primary osteoblasts and MC 3T3 osteoblast-like cells, IL-6 production, release, and gene expression were investigated with enzyme-linked immunosorbent assay (ELISA) and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) techniques, respectively. Results In calvariae, s 2 m induced a time- and dose-dependent calcium release, which was maximum following a 48-hour incubation at a concentration of 10 -5 mol/L. s 2 m (10 -6 mol/L) also induced a significant release of IL-6 from calvarial and primary osteoblastic cultures. Using 10 -6 mol/L s 2 m, the amount of IL-6 mRNA in MC 3T3 cells increased in a time-dependent fashion, which peaked at 3 hours and declined to baseline by 12 hours. In primary osteoblast cells, s 2 m maximally increased IL-6 mRNA levels at 6 hours; however, they remained elevated up to 24 hours. Compared with control, the presence of s 2 m significantly increased cell proliferation of both primary osteoblasts and MC 3T3 cells. To investigate osteoblastic function further, osteocalcin mRNA was quantitated. Incubation with s 2 m for 3 to 24 hours did not alter the amount of osteocalcin mRNA in the MC 3T3 osteoblast cells. Conclusion β 2 m affects bone metabolism by mechanisms that include increasing IL-6 gene expression and release, and enhancing osteoblast proliferation without affecting osteocalcin gene expression.
Career transition from clinician to academician: responsibilities and reflections

Being an educator is just as much an art and a science as is being a clinician. This article describes the faculty role and its basic responsibilities for occupational therapy practitioners who are considering the transition to academic educator positions. The faculty role has unique characteristics. Differentiating therapy activities from academic activities is an essential part of a career transition from clinician to academician. This article also describes the various features of the academic context and its impact on individual performance, how to assess readiness for the faculty role, and the typical application process.
Cell line-dependent differences in uptake and retention of the hypoxia-selective nuclear imaging agent Cu-ATSM.

Abstract Background Cu-diacetyl-bis( N 4 -methylthiosemicarbazone) [Cu-ATSM] is a potential marker for tumor hypoxia that has been under evaluation for clinical use. In this study, we examined the mechanisms underlying the uptake of 64 Cu in cells incubated with 64 Cu-ATSM. Methods The in vitro uptake of 64 Cu was determined as a function of oxygenation conditions and incubation time with 64 Cu-ATSM using four and two tumor cell lines of human origin and rodent origin, respectively. Additionally, the rate of 64 Cu efflux and Cu-ATSM metabolism was determined. Results 64 Cu accumulation is rapid during the first 0.5–1 h of incubation. It is highest in anoxic cells but is also significant in normoxic cells. After this initial period, the level of intracellular 64 Cu varies depending on the cell line and the oxygenation conditions and, in some circumstances, may decrease. During the first 0.5–1 h, the ratio of 64 Cu levels between anoxic and normoxic cells is ∼2:10 and that between hypoxic (0.5% O 2 ) and normoxic cells is ∼1:2.5, depending on the cell line. These ratios generally decrease at longer times. The 64 Cu-ATSM compound was found to be metabolized during incubation in a manner dependent on oxygenation conditions. Within 2 h under anoxic conditions, 64 Cu-ATSM could no longer be detected, although 60–90% of the amount of 64 Cu added as 64 Cu-ATSM was present in the medium. Non-ATSM 64 Cu was taken up by the cells, albeit at a much slower rate. Efflux rates of 64 Cu were found to be cell line dependent and appeared to be inversely correlated with the final 64 Cu uptake levels under anoxic conditions. Conclusion The uptake and retention of 64 Cu and their relation to oxygenation conditions were found to be cell line dependent. Given the complexities in the oxygen dependence and cell line-dependent kinetics of uptake and retention of Cu following exposure to Cu-ATSM, the clinical utility of this compound may be disease site specific.
Absence of an early effect of glucocorticoids on nonesterified fatty acid accumulation in isolated rat thymus cells

Abstract Nonesterified fatty acid levels have been measured in isolated rat thymocytes incubated with or without 1.3 μM cortisol for 2 h. No significant cortisol effect on nonesterified fatty acid levels was observed, though the well-established early effect of cortisol on glucose uptake was present. Since other work has shown that by two hours thymus cells exposed to similar concentrations of cortisol already manifest a number of changes that appear closely related to subsequent cytolysis. it seems unlikely that stimulation of nonesterified fatty acid accumulation can be a primary cause of cytolysis or that it is involved in the early effect of glucocorticoids on thymus cells.
Superiority of quantitative exercise thallium-201 variables in determining long-term prognosis in ambulatory patients with chest pain: a comparison with cardiac catheterization

Abstract The purpose of this study was to determine the prognostic utility of quantitative exercise thallium-201 imaging and compare it with that of cardiac Catheterization in ambulatory patients. Accordingly, long-term (4 to 9 years) follow-up was obtained in 293 patients who underwent both tests for the evaluation of chest pain: 89 had undergone coronary artery bypass graft surgery within 3 months of testing and were excluded from analysis, 119 experienced no cardiac events and 91 had an event (death in 20, nonfatal myocardial infarction in 21 and coronary artery bypass operations performed > 3 months after cardiac catheterization in 50). When all variables were analyzed using Cox regression analysis, the quantitatively assessed lung/heart ratio of thallium-201 activity was the most important predictor of a future cardiac event (χ2= 40.21). Other significant predictors were the number of diseased vessels (χ2= 17.11), patient gender (χ2= 9.43) and change in heart rate from rest to exercise (χ2= 4.19). Whereas the number of diseased vessels was an important independent predictor of cardiac events, it did not add significantly to the overall ability of the exercise thallium-201 test to predict events. Furthermore, information obtained from thallium-201 imaging alone was marginally superior to that obtained from cardiac Catheterization alone (p = 0.04) and significantly superior to that obtained from exercise testing alone (p = 0.02) in determining the occurrence of events. In addition, unlike the exercise thallium-201 test, which could predict the occurrence of all categories of events, Catheterization data were not able to predict the occurrence of nonfatal myocardial infarction. The exclusion of bypass surgery and previous myocardial infarction did not alter the results. In conclusion, data from this study demonstrate that exercise thallium-201 imaging may be superior to data from both exercise testing alone and cardiac Catheterization data alone for predicting future events in ambulatory patients who have undergone both exercise thallium-201 imaging and Catheterization for the evaluation of chest pain.
Tapping dynamics for a column of particles and beyond

The dynamics of a vertical stack of particles subject to gravity and a sequence of small, periodically applied taps is considered. First, the motion of the particles, assumed to be identical, is modeled as a system of ordinary differential equations, which is analyzed with an eye to observing connections with finite-dimensional Hamiltonian systems. Then, two approaches to obtaining approximate continuum models for large numbers of particles are described: the long-wave approximation that yields partial differential equations and the BSR method that employs integro-partial differential models. These approximate continuum models, which comprise infinite-dimensional dynamical systems, are studied with a focus on nonlinear wave type behavior, which naturally leads to investigating links to infinite-dimensional Hamiltonian systems. Several examples are solved numerically to show similarities among the solution properties of the finite-dimensional (lattice-dynamics), and the approximate long-wave and BSR continuum models. Extensions to higher dimensions and more general dynamically driven particle configurations are also sketched.
Superactive somatostatin analog decreases plasma glucose and glucagon levels in diabetic rats.

Abstract The action of the new analog of somatostatin, D-Phe- Cys-Tyr-D-Trp-Lys-Val-Cys -Trp-NH2 (RC-160), on plasma glucagon and glucose levels was evaluated in streptozotocin-diabetic rats. The effect of this analog on the insulin-induced hypoglycemia in diabetic rats was also investigated in order to evaluate the risk of exacerbating hypoglycemia. Administration of analog RC-160, in a dose of 25 μg/kg b.wt. SC, inhibited plasma glucagon secretion and decreased plasma glucose levels. This effect also occurred when plasma glucagon and glucose levels were first elevated by arginine infusion, 1000 mg/kg/hr for 30 min. Subcutaneous injection of regular insulin, 15 U/kg b.wt., produced hypoglycemia with a progressive increase in glucagon levels. Analog RC-160 completely suppressed the hypoglycemia-induced glucagon release for up to 150 min after injection of the analog or insulin. A greater decrease in the plasma glucose level was observed in the group treated with insulin and the analog than in the group injected only with insulin. These results indicate that somatostatin analog RC-160 can produce a marked and prolonged inhibition of glucagon release and a decrease in the plasma glucose level in diabetic rats. This analog may be useful as an adjunct to insulin in the treatment of diabetic patients, although caution should be exercised, to prevent hypoglycemia when using somatostatin analogs together with insulin.
Considerations in assessing the evidence and implications of aid displacement from the health sector.

Eran Bendavid and Rajaie Batniji provide a perspective on the ongoing debates about aid displacement - whether giving development aid to governments leads to reductions in their own domestic health financing.
Tungsten nitride thin films deposited by MOCVD: sources of carbon and effects on film structure and stoichiometry

MOCVD was used to deposit tungsten nitride thin films from solutions of Cl 4 (CH 3 CN)W(N i Pr) in 1,2-dichlorobenzene (1,2-DCB). Results were compared to previous depositions from benzonitrile (PhCN) solutions in order to determine whether the solvent affected deposition of carbon into the films. The rate of carbon deposition was solvent-dependent, with apparent activation energies in films from PhCN and 1,2-DCB solutions being 0.70±0.10 eV and 1.0±0.14 eV, respectively. Residual gas analysis results were consistent with solvent decomposition in the reactor, and increased nitrogen levels for films from PhCN solutions suggest that the nitrile (CN) group was a significant carbon source.
Hdac6 regulates Tip60-p400 function in stem cells

Embryonic stem cells are cells that are able to transform into many other types of cells, such as blood cells and skin cells, as well as being able to divide in order to produce more stem cells. Mature cells lack this ability, which is called pluripotency, which is why there is so much interest in using embryonic stem cells to replace or regenerate human cells that have been lost or damaged through injury or illness. The various processes that result in self-renewal (the production of new stem cells) or differentiation (the production of other types of cells) are controlled by a wide variety of pathways, including some that only apply to the regulation of gene expression in stem cells. A number of these processes are known to involve chromatin – the densely packed structure formed by DNA and proteins called histones. Now Chen et al. study the means by which chromatin controls the stem cell fates by examining how a large enzyme called Tip60-p400 that interacts with histones – one of the main components of chromatin – in both mature cells and embryonic stem cells. Tip60-p400 is known to switch on genes that cause stem cells to undergo self-renewal, and to switch off the genes that allow stem cells to transform into other cell types, but the molecular mechanisms responsible for these effects have not yet been identified. Chen et al. studied the activity of Tip60-p400 in mouse embryonic stem cells, and found that another enzyme, Hdac6, had to be present for Tip60-p400 to regulate the genes in the stem cells. Hdac6 is mostly found in the cytoplasm of cells that have differentiated into other cell types, and in the nucleus of stem cells, which is where the DNA resides. In cells from mice that lack Hdac6, Chen et al. also found that stem cells fail to replicate or differentiate properly in culture, underscoring the importance of this particular enzyme, and filling in another piece of the puzzle of stem cell biology.
Plasma Membrane Permeabilization by Trains of Ultrashort Electric Pulses

Ultrashort electric pulses (USEP) cause long-lasting increase of cell membrane electrical conductance, and that a single USEP increased cell membrane electrical conductance proportionally to the absorbed dose (AD) with a threshold of about 10 mJ/g. The present study extends quantification of the membrane permeabilization effect to multiple USEP and employed a more accurate protocol that identified USEP effect as the difference between post- and pre-exposure conductance values (Δg) in individual cells. We showed that Δg can be increased by either increasing the number of pulses at a constant E-field, or by increasing the E-field at a constant number of pulses. For 60-ns pulses, an E-field threshold of 6 kV/cm for a single pulse was lowered to less than 1.7 kV/cm by applying 100-pulse or longer trains. However, the reduction of the E-field threshold was only achieved at the expense of a higher AD compared to a single pulse exposure. Furthermore, the effect of multiple pulses was not fully determined by AD, suggesting that cells permeabilized by the first pulse(s) in the train become less vulnerable to subsequent pulses. This explanation was corroborated by a model that treated multiple-pulse exposures as a series of single-pulse exposures and assumed an exponential decline of cell susceptibility to USEP as Δg increased after each pulse during the course of the train.
Syntheses and characterization of nanometer-sized semiconductor clusters

During the past few years a wide variety of synthetic teainiques have been developed to prepare semiconductor clusters in the nanometer size regime. These clusters possess properties which are intermediate between the molecular and bulk limits and can be considered a new class of materials. In this paper, we review their synthesis and discuss recent developments as well as possible future directions.
Low field 11B nmr in YRh4B4

Abstract An adiabatic field cycling technique is used to study the 11 B nmr in the anomalous ternary superconductor YRh 4 B 4 at fields below H c1 .
Autoregulation of 2μm circle gene expression provides a model for maintenance of stable plasmid copy levels

The yeast plasmid 2 micron circle actively maintains high but stable copy levels in the cell, even though the plasmid confers no selective advantage to its host. To address the mechanism by which stable copy control is achieved, we have examined the level of expression of the genes resident on the yeast plasmid 2 micron circle as a function of the presence of proteins encoded by the plasmid. We find that transcription of the site-specific recombinase gene, FLP, is repressed at least 100-fold by the concerted action of the products of two other plasmid genes, REP1 and REP2. In addition, these products repress transcription of the REP1 gene itself. These results can be formulated into a consistent model for plasmid copy control.
Transamination in Rhodospirillum rubrum.

Abstract Whole cell and cell extracts of Rhodospirillum rubrum grown in the dark or light contain transaminases which catalyze the formation of glutamate from α-ketoglutarate and the following amino acids: phenylalanine, aspartate, tyrosine, ornithine, valine, leucine, isoleucine, tryptophan, histidine, and alanine. Methionine and lysine are slightly active as amino donors. d -Glutamate-oxalacetate and d -glutamate-pyruvate transaminases are present in the cell-free extract.
Prostate-specific antigen screening among young men in the United States.

BACKGROUND. Disagreement exists on the use of prostate-specific antigen (PSA) tests for cancer-risk stratification in young men in the United States. Little is known about the use of PSA testing in these men. To understand policy implications of risk stratification, the authors sought to characterize PSA use among young men. METHODS. The authors used the 2002 Behavioral Risk Factor Surveillance System to study prostate-cancer screening in a representative sample of men aged 40 years and older (n 5 58,511). The primary outcome was self-report of a PSA test in the previous year. RESULTS. Among men aged 40 to 49 years, 22.5% (95% confidence interval [CI], 21.5-23.5) reported having had a PSA test in the previous year, compared with 53.7% (95% CI, 52.8-54.7; P < .001) of men aged � 50 years. When sociodemographic characteristics were statistically controlled, young, black, non-Hispanic men were more likely than young, white, non-Hispanic men to report having had a PSA test in the previous year (odds ratio [OR], 2.42; 95% CI, 1.95-3.01; P < .001). In young men, annual household income � $35,000 (OR, 1.50; 95% CI, 1.26-1.78; P < .001) and an ongoing relationship with a physician (OR, 2.52; 95% CI, 2.06-3.07; P < .001) were associated with PSA testing. CONCLUSIONS. One-fifth of young men reported having had a PSA test within the previous year. Young, black, non-Hispanic men are more likely than young, white, non-Hispanic men to report having had a PSA test, although screening in this high-risk group remains suboptimal. Cancer 2008;113:1315–23. � 2008 American Cancer Society.
On arithmetic expressions and trees

A description is given of how a tree representing the evaluation of an arithmetic expression can be drawn in such a way that the number of accumulators needed for the computation can be represented in a straightforward manner. This representation reduces the choice of the best order of computation to a specific problem under the theory of graphs. An algorithm to solve this problem is presented.
Adult Day Care Center: A Unique Clinical Experience for Dietetic Students

Senior dietetic students worked closely with an elderly population and respective caregivers in an adult day-care program. Experiences included preparation of nutritional assessments, design of appropriate case management, and counseling clients and families. Nutrition education programs consonant with age-related changes in learning were planned and implemented. The food service system was monitored to assure that the needs of an aging group with diverse dietary needs were met. Students enjoyed a valuable experience working with a growing population and gained an appreciation of how heterogeneous today's elders are.
A FOCUSED TRANSPORT APPROACH TO PICKUP ION SHOCK ACCELERATION: IMPLICATIONS FOR THE TERMINATION SHOCK

The discovery of low-energy suprathermal ions coming directly from the solar wind termination shock by the Voyager 1 spacecraft revealed strong beaming of these particles along the direction of the large-scale magnetic field. Since such large anisotropies exclude the use of standard cosmic-ray transport theory for nearly isotropic particle distributions in modeling the acceleration of these particles at the termination shock, we developed a shock acceleration model based on the numerical solution of the standard focused kinetic transport equation. After investigating the appropriateness of the physical content of this equation for shock acceleration, and applying the model to shocks of varying shock obliquity, we find that (1) this approach is a viable alternative to more sophisticated particle codes such as hybrid codes for simulating the shock acceleration of pickup ions and (2) that the model has the potential to reproduce many of the interesting features of energetic ions observed by the Voyager spacecraft at the termination shock.
Introduction: equality and inequality in information societies, part II

The second part of a two-part symposium in Social Science Computer Review devoted to equality and inequality in information societies, the three contributions to this issue focus on the growing importance of information technology (IT) in less developed countries and the gnawing disparities in IT access and impact with more developed countries, the focus of the symposium’s first part (see Social Science Computer Review, Winter 1998).
Relationships between bridging oxygen 17O quadrupolar coupling parameters and structure in germanates

We have performed ab initio calculations on the model cluster (OH)3Ge–O–Ge(OH)3 in order to refine the relationships between 17O quadrupolar coupling parameters and the local structure around the bridging oxygen. From these calculations the trend in the bridging oxygen 17O quadrupolar coupling constant, Cq, and asymmetry parameter, ηq, with changing Ge–O–Ge angle was found to be similar to previously established trends in silicate clusters with the overall Cq values being systematically increased in magnitude by approximately 3 MHz. Such a shift can be attributed to differences in cation–oxygen distances as well as coordinating cation electronegativity. In addition, we also investigated the effect of changing intratetrahedron bond angles over a range that has been suggested to exist in germanate systems. While such variations in intratetrahedron bond angles lead to a small variation in Cq, ηq remains relatively unaffected. In such cases, ηq can still be a reliable probe of Ge–O–Ge angle while Cq could serve as a probe of tetrahedron distortions.
Reference data for arm muscle and arm adipose tissue areas in Mexican Americans from the Hispanic Health and Nutrition Examination survey (HHANES 1982-1984): Comparisons with whites and blacks from NHANES II (1976-1980).

Data for arm muscle area (AMA) and arm adipose tissue area (AATA) from 3695 Mexican American children 6 months to 18 years of age included in HHANES (1982-1984) were used to obtain age-and gender-specific means and selected percentiles. These statistics were compared with those for non-Hispanic white and non-Hispanic black children from NHANES II (1976-1980). In comparison with non-Hispanic white and non-Hispanic black children, the Mexican American children tended to have smaller means and percentile values for AMA but larger values for AATA. There was considerable sexual dimorphism in AMA and AATA. Within each population, boys tended to have larger means and percentile values for AMA than girls, and girls tended to have larger values for AATA than boys. Within each population of boys, there was a prepubescent gain in AATA, followed by a midpubescent loss, and then an increase near the middle of the second decade. This "fat wave" pattern was not noticeable in girls. Population differences in age- and gender-specific mean values for AMA and AATA were small. Few statistically significant differences were observed; these were no more common than would occur by chance. Therefore, population-specific reference data for AMA and AATA may not be needed for the clinical evaluation of Mexican Americans, non-Hispanic blacks, and non-Hispanic whites. © 1996 Wiley-Liss, Inc.
Structure and Arrangement of Salivary Gland Chromosomes in Drosophila Species.

The salivary gland nuclei in Drosophila contain two different chromosome derivatives, the long chromosome strands which correspond to the euchromatic parts of prophase chromosomes, and the chromocenter which arises from the heterochromatic regions (Heitz [2]). While most investigators now agree that the euchromatic strands are composed of a number of closely united chromonemata, the homologous chromomeres of which form discs (aggregate chromomeres), there is no uniformity of opinion regarding the chromocenter. Painter [3] considered it an aggregate of accessory material into which each chromosome sends a thin achromatic strand. Muller and Prokofjeva [4] believe that these regions show the same regular banding as the euchromatic parts. Koller' calls the chromocenter an "undifferentiated magma."
Behavioural variation in natural populations. V. Morphological correlates of locomotion in the garter snake (Thamnophis radix)

A series of morphologieal and locomotor performance variables was measured in a population of newborn garter snakes to determine whether performance capacity has a significant morphological basis in these animals. Morphological traits measured were body length and mass, number of body and tail vertebrae and numbers of vertebral abnormalities. Locomotor performances included burst and mid-distance speed and distance and time crawled before anti-predator displays were assumed. All performance variables were repeatable in daily replicate trials (P < 0.001). Individual burst speed, mid-distance speed, and distance crawled were significantly correlated pairwise (P < 0.01). Most morphological and performance variables had a significant mass dependence (static allometry), although the effects were rather weak (r2 < 0.1, except for body length): larger animals performed better and had fewer abnormalities. There were significant associations between some morphological traits and locomotor performance. Morphological factors accounted for 19% of the variation in mid-distance speed and 14% of the variation in antipredator behavior by multiple regression analysis. Canonical correlation of all performance and morphological variables simultaneously accounted for 24% of the observed variation in performance. Numbers of body and tail vertebrae (assayed by scale counts) had an interactive effect on speed of locomotion.
High efficiency micellar electrokinetic chromatography of hydrophobic analytes on poly(dimethylsiloxane) microchips.

This paper describes a simple method for the effective and rapid separation of hydrophobic molecules on polydimethylsiloxane (PDMS) microfluidic devices using Micellar Electrokinetic Chromatography (MEKC). For these separations the addition of sodium dodecyl sulfate (SDS) served two critical roles – it provided a dynamic coating on the channel wall surfaces and formed a pseudo-stationary chromatographic phase. The SDS coating generated an EOF of 7.1 × 10−4 cm2 V−1 s−1 (1.6% relative standard deviation (RSD), n = 5), and eliminated the absorption of Rhodamine B into the bulk PDMS. High efficiency separations of Rhodamine B, TAMRA (6-carboxytetramethylrhodamine, succinimidyl ester) labeled amino acids (AA), BODIPY® FL CASE (N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionyl)cysteic acid, succinimidyl ester) labeled AA's, and AlexaFluor® 488 labeled Escherichia coli bacterial homogenates on PDMS chips were performed using this method. Separations of Rhodamine B and TAMRA labeled AA's using 25 mM SDS, 20% acetonitrile, and 10 mM sodium tetraborate generated efficiencies > 100 000 plates (N) or 3.3 × 106 N m−1 in <25 s with run-to-run migration time reproducibilities <1% RSD over 3 h. Microchips with 30 cm long serpentine separation channels were used to separate 17 BODIPY® FL CASE labeled AA's yielding efficiencies of up to 837 000 plates or 3.0 × 106 N m−1. Homogenates of E. coli yielded ∼30 resolved peaks with separation efficiencies of up to 600 000 plates or 2.4 × 106 N m−1 and run-to-run migration time reproducibilities of <1% RSD over 3 h.
Electrospray ionization of nucleic acid aptamer/small molecule complexes for screening aptamer selectivity.

Molecular recognition of small molecule ligands by the nucleic acid aptamers for tobramycin, ATP, and FMN has been examined using electrospray ionization mass spectrometry (ESI-MS). Mass spectrometric data for binding stoichiometry and relative binding affinity correlated well with solution data for tobramycin aptamer complexes, in which aptamer/ligand interactions are mediated by hydrogen bonds. For the ATP and FMN aptamers, where ligand interactions involve both hydrogen bonding and significant π-stacking, the relative binding affinities determined by MS did not fully correlate with results obtained from solution experiments. Some high-affinity aptamer/ligand complexes appeared to be destabilized in the gas phase by internal Coulombic repulsion. In CAD experiments, complexes with a greater number of intermolecular hydrogen bonds exhibited greater gas-phase stability even in cases when solution binding affinities were equivalent. These results indicate that in at least some cases, mass spectrometric data on aptamer/ligand binding affinities should be used in conjunction with complementary techniques to fully assess aptamer molecular recognition properties. Copyright © 2005 John Wiley & Sons, Ltd.
Direct and Indirect Implications of Pathogen Prevalence for Scientific and Technological Innovation

Rates of scientific and technological innovation vary widely across cultures, but why? Given the previously documented effects of disease threat on cultural values and traits that inhibit innovation, this variation may be due, at least in part, to regional variation in the prevalence of disease-causing pathogens. Five country-level measures of innovation were used to investigate this hypothesis. Preliminary results revealed that pathogen prevalence was significantly associated with all five measures of innovation. Further analyses revealed that pathogen prevalence significantly predicted innovation when statistically controlling for other purported causes of cross-cultural variation in innovation, such as education, wealth, and population structure. Finally, mediational analyses revealed that the effect of disease prevalence on innovation was mediated by levels of collectivism and conformity. These results demonstrate that the previously documented impact of disease threat on cultural value systems may ha...
DYNAMICAL CLUSTERING AS A GENERATOR OF COMPLEX SYSTEM DYNAMICS

The challenge to understand the dynamics of Complex Systems is attracting attention from a wide range of disciplines across the natural, biological and social sciences. Recent turmoil in the financial markets has brought this challenge into the public domain, with speculation rife as to the root cause of the observed fluctuations. At their heart, all Complex Systems share the common property of featuring many interacting objects from which the observed macroscopic dynamics emerge. Exactly how this happens cannot yet be specified in a generic way — however, an important milestone in this endeavor is to develop a quantitative understanding of any internal clustering dynamics within the population. Coalescence-fragmentation processes have been studied widely in conventional chemistry and physics — however, collective behavior in social systems is not limited by nearest-neighbor interactions, nor are the details of social coalescence or fragmentation processes necessarily the same as in physical and biological systems. Here we discuss the general phenomenon of coalescence and fragmentation problems with a focus on social systems in which a typical fragmentation process corresponds to an entire group breaking up, as opposed to the typical binary splitting studied in physical and biological systems. Having discussed situations under which power-laws for the group distribution size emerge from such internal clustering dynamics, we move on to look at the specific application to financial markets. We propose a new model for financial market dynamics based on the combination of internal clustering (i.e. herding) dynamics with human decision-making. The resulting fluctuation in price movements is closer to what is observed empirically, leading us to speculate that the combination of dynamical clustering and decision-making are key for developing quantitative models of social dynamical phenomena.
The development of suicide ideation and attempts: an epidemiologic study of first graders followed into young adulthood

Studying community residing youths originally recruited for an intervention trial upon entry into first grade, this project sought to estimate risk of suicide ideation and attempts to young adulthood, with focus on those who used drugs before age 16, as compared to youths who used later in development or not at all. Standardized interview assessments in 1989-1994 were completed with 2311 youths age 8-15. Roughly 15 years after recruitment, our study team reassessed 1695, nearly 75% of the survivors (mean age = 21), finding 155 to have made suicide attempts (SA) and 218 with onset of depression-related suicide ideation (SI). We estimate relative risk (RR), from survival analysis and logistic regression models, to study early use of tobacco, alcohol, cannabis, and inhalants, with covariate adjustments for age, sex, race-ethnicity, and other pertinent covariates. Early-onset of cannabis use and inhalant use for females, but not for males, signaled modestly excess risk of suicide attempt (cannabis-associated RR = 1.9; p = 0.04; inhalant-associated RR = 2.2; p = 0.05). Early-onset of cannabis use by females (but not for males) signaled excess risk for suicide ideation (RR = 2.9; p = 0.006). Early-onset alcohol and tobacco use were not associated with later risk of SA or SI. In light of the relatively modest strength of association, the evidence may well reflect an underlying common diathesis or unmeasured prior confounding influences that link early-onset illegal drug use with later risk of these suicide-related events, rather than an influence of early-onset drug use per se.
Evaluation of organic markers for chemical mass balance source apportionment at the Fresno Supersite

Sources of PM2.5 at the Fresno Supersite during high PM2.5 episodes occurring from 15 December 2000-3 February 2001 were estimated with the Chemical Mass Bal- ance (CMB) receptor model. The ability of source profiles with organic markers to distinguish motor vehicle, residen- tial wood combustion (RWC), and cooking emissions was evaluated with simulated data. Organics improved the dis- tinction between gasoline and diesel vehicle emissions and allowed a more precise estimate of the cooking source con- tribution. Sensitivity tests using average ambient concen- trations showed that the gasoline vehicle contribution was not resolved without organics. Organics were not required to estimate hardwood contributions. The most important RWC marker was the water-soluble potassium ion. The es- timated cooking contribution did not depend on cholesterol because its concentrations were below the detection limit in most samples. Winter time source contributions were esti- mated by applying the CMB model to individual and average sample concentrations. RWC was the largest source, con- tributing 29-31% of measured PM2.5. Hardwood and soft- wood combustion accounted for 16-17% and 12-15%, re- spectively. Secondary ammonium nitrate and motor vehicle emissions accounted for 31-33% and 9-15%, respectively. The gasoline vehicle contribution (3-10%) was comparable to the diesel vehicle contribution (5-6%). The cooking con- tribution was 5-19% of PM2.5. Fresno source apportionment results were consistent with those estimated in previous stud- ies.
Development of novel traveling wave tube amplifiers for V-band microwave power modules (MPMs) at the Northern Illinois University (NIU)

We examine various schemes of novel traveling wave tube (TWT) amplifiers at the Northern Illinois University (NIU) in an effort to develop a compact, high power V-band microwave power module using small signal theory and particle-in-cell (PIC) simulation. Our prior work includes theoretical and numerical assessment on performance of the aluminum-nitride (AlN)-loaded multi-beam TWT circuit, indicating that the TM 31 -mode is amplified with 15-20 dB/beam at 64-84 GHz with three elliptical beams, simultaneously suppressing lower order modes (TM 11 , and TM 21 ). The same analysis also shows that cascading 6-7 slow wave circuits in tandem also enables 50 W of output power with 30 dB gain, which could be integrated on a single board substrate with multi-beam emitters by micro-fabrication. More schemes to improve device performance and to reduce physical sizes are continuously explored in advancing millimeter and sub-millimeter vacuum electronics.
Correspondence of Escape-Turning Behavior with Activity of Descending Mechanosensory Interneurons in the Cockroach, Periplaneta americana

Two bilaterally paired mechanosensory neurons that respond to antennal touch stimulation recently have been described in the cockroach Periplaneta americana. Here chronic recordings were used to describe the activity of these interneurons in relation to behavior. Parallel intra/extracellular recording experiments showed that both pairs of previously identified descending mechanosensory interneurons (DMIs) were activated after touch stimulation of the antennae and before initiation of escape. On a trial-by-trial basis, the bilateral pattern of their activity was correlated with sensory input and behavior: when one antenna was touched, the contralateral DMI axons displayed impulses earlier and in greater numbers than their ipsilateral homologs; turns were made toward the side with greater DMI activity, i.e., away from the touched antenna. One parameter of DMI activity (the bilateral difference in number of DMI impulses) was correlated with the angular amplitude of turning. In the absence of touch stimulation, unilateral electrical stimulation of a cervical connective via the chronic electrodes produced turning movements similar to natural escape turning and of appropriate directionality. These results support the hypothesis that neural activity in DMIs is involved in the control of antennal touch-evoked escape, and they provide a basis for a model of DMI specification of the direction of escape turning.
CONSTITUENTS OF ELEMENTARY BODIES OF VACCINIA II. PROPERTIES OF NUCLEIC ACID OBTAINED FROM VACCINE VIRUS

It has been possible by means of classical chemical methods to isolate and to characterize to some extent the nucleic acid of elementary bodies of vaccinia. Determination by means of diphenylamine reagent revealed that the major part of the nucleic acid was of the thymus type. This was further substantiated by its stability in the presence of ribonuclease, less than 10 per cent undergoing depolymerization during prolonged incubation at 37°C. By the technique employed, at least 5.6 per cent of the virus was shown to be thymonucleic acid. This amount agreed favorably with the value calculated from the non-lipid organic phosphorus of elementary bodies on the assumption that the phosphorus bound in the organic form was derived principally from nucleic acid.
Socio-Technical Interaction Networks in Free/Open Source Software Development Processes

This chapter explores patterns of social and technological interaction that emerge in free/open source software development (F/OSSD) projects found in different research and development communities. F/OSSD is a relatively new way for building and deploying large software systems on a global basis, and differs in many interesting ways from the principles and practices traditionally advocated for software engineering. Hundreds of F/OSS systems are now in use by thousands to millions of end-users, and some of these F/OSS systems entail hundreds-of-thousands to millions of lines of source code. So what’s going on here, and how are F/OSSD processes that are being used to build and sustain these projects different?
Ischemic hepatitis : clinical presentation and pathogenesis

Abstract BACKGROUND: The pathophysiology of ischemic hepatitis, otherwise known as "shock liver," is poorly understood, although it is believed to be the result of a reduction in systemic blood flow as typically occurs in shock. The aim of this study was to investigate the importance of this phenomenon as well as other clinical features in patients with ischemic hepatitis. METHODS: We identified a cohort of 31 patients (case group) who met the most commonly accepted definition of ischemic hepatitis (an acute reversible elevation in either the serum alanine or aspartate aminotransferase level of at least 20 times the upper limit of normal, excluding known causes of acute hepatitis or hepatocellular injury, in an appropriate clinical setting). We also evaluated the clinical features and serum aminotransferase levels in a cohort (the control group) of 31 previously healthy patients who sustained major nonhepatic trauma at San Francisco General Hospital, a major trauma center. Both groups of patients had documented systolic blood pressures RESULTS: Despite the marked reduction in blood pressure, no patient in the control group developed ischemic hepatitis. The mean (± SD) peak serum aspartate aminotransferase level in the control group was only 78 ± 72 IU, in contrast with a mean peak of 2,088 ± 2,165 IU in the case group. All 31 patients with ischemic hepatitis had evidence of underlying organic heart disease, 29 (94%) of whom had right-sided heart failure. CONCLUSIONS: Systemic hypotension or shock alone did not lead to ischemic hepatitis in any patient. The vast majority of patients with ischemic hepatitis had severe underlying cardiac disease that had often led to passive congestion of the liver. These data lead us to propose that right-sided heart failure, with resultant hepatic venous congestion, may predispose the liver to hepatic injury induced by a hypotensive event.
Sources of Compass Error in Tunnel Mapping

Six sets of compass measurements were performed in tunnels in igneous rock at the Nevada Test Site. The measurement sets were analyzed to evaluate the influences of wire mesh, rock bolts, mining equipment, and steel arches on compass-based geologic mapping work. Analysis revealed that wire mesh within one foot of the compass, rock bolts within one and one-half feet, or mining equipment (such as a drill jumbo) within two feet would cause deviations in the compass readings which could lead to errors in mapping. Steel arches affected the compass with an apparent “cage effect” that virtually precluded use of the magnetic compass for mapping.