cssi/SciSciGPT-SciSciNet huggingface dataset:
Some filtering results in Riemann manifolds

Some stochastic filtering problems are formulated and solved where the observations are described by stochastic differential equations in the tangent bundle of a compact Riemann manifold. The stochastic differential equations in the tangent bundle are formulated and solved by using the notion of parallelism of vectors along a curve. A stochastic differential equation is obtained for the evolution of the estimate of a suitable process given the observations. An example is solved that exploits the linear filtering results.
Disappearance of grating induction at scotopic luminances.

Abstract The dependence of grating induction magnitude on retinal illuminance was examined in two subjects. Grating induction magnitude, as determined using the cancellation technique of McCourt (Vision Research, 22, 119–134, 1982), declines monotonically with decreasing retinal illuminance, effectively disappearing at a value of 0.3–0.5 phot td. In a second experiment, sensitivity differences for test lights of 500 and 600 nm were measured as a function of background illuminance in order to gauge the luminance operating range for grating induction with respect to duplex photoreceptor function. Cancelling contrast (and hence grating induction magnitude) fell below detection threshold contrast at retinal illuminances coinciding with the transition from photopic to scotopic visual function. In a third experiment, spatial contrast sensitivity was measured using both spatially extended (10°) and truncated (2°) sinewave gratings at frequencies below 2 c/deg, at three values of retinal illuminance. Illuminance values corresponded to those where grating induction magnitude was, as determined from the first experiment, either maximal, intermediate or negligible. Similar to grating induction, the strength of lateral inhibition, as indexed by the slope of the low-frequency decline in contrast sensitivity, is progressively reduced with decreasing retinal illuminance, particularly for the 2° field. There was, however, using the same criteria, evidence of lateral inhibition at a value of retinal illuminance which did not support grating induction. The implications of these results are discussed with respect to classical brightness contrast phenomena, recent neuroanatomical and neurophysiological evidence of segregated parvo- and magnocellular mediated contrast processing systems, and with results from previous studies of the grating induction effect.
CHROMOSOME NUMBERS IN COMPOSITAE. XI. HELENIEAE

Reports of 89 new counts are recorded for the tribe Helenieae, including reports for 28 genera and 56 species. One genus, Hypericophyllum (n 9), and six other taxa were previ-
Literacy and Language Change: The Special Case of Speech Act Verbs

This paper explores the methodological and theoretical issues that need to be addressed in testing the validity of proposed correlations between the rise of a certain class of words and the development of literacy. Olson and Astington (in press) suggest a correlation between the rise of a) assertive speech act verbs such asobserve,state, andclaim, b) literacy, and c) the Enlightenment. Data from the history of speech act verbs in English do not provide evidence for any privileged correlation with the Enlightenment, since assertives abound from Old and especially Middle English on. Possible correlations with literacy point not to writing as the motivating force but rather to the language of the law-courts, feudal practices, and rhetorical debate in the Middle Ages.
Considering alternative strategies for value sustainment in systems-of-systems

Systems of Systems (SoSs) operating in an uncertain world must overcome a variety of challenges in order to sustain value delivery over time. This paper describes strategies for value sustainment, using an application of the “wave model” to represent time-varying SoS Engineering (SoSE) activities and opportunities for SoS-change. A Maritime Security (MarSec) SoS case study is described, and simulation-based Era Analysis is used to evaluate SoS alternatives through different operational environments for an assumed 8-year time frame. Eight SoS designs are evaluated and compared across four strategies in terms of accumulated utility, discounted cost, and total down time. The four value sustainment strategies are: (1) self-recovery, the SoS is not changed (i.e., relating to survivability/robustness); (2) changes in the design of the SoS are allowed (i.e., relating to changeability); (3) changes in the architecture of the SoS are allowed (i.e., relating to evolvability) once, or (4) three times in the eight years. The results provide an example of how quantitative approaches can be used to gain insights into tradeoffs in how SoS architects can create value-sustainable SoSs for the long run.
Real-time multicast for wireless multihop networks

Abstract Wireless multicast for multihop ad-hoc networks ensures that the same information is delivered efficiently to multiple recipients simultaneously. However, existing protocols ignore the real-time nature of many wireless applications such as real-time video and audio communications in mesh and ad-hoc networks. Further, devices in such networks are typically energy-constrained, i.e., multicast protocols have to trade off timeliness with energy efficiency. This paper presents RTMC, a real-time multicast protocol for wireless multihop networks that allows receivers to specify their individual real-time constraints and establishes multicast trees such that receivers’ deadlines are met and overall energy consumption in the network is reduced. Toward this end, RTMC relies on dynamically prioritized packet scheduling on forwarding nodes, prioritized channel access at the MAC layer, feedback control for latency management, tree adaptations to address mobility, dynamic subscriptions and unsubscriptions, and adaptations to address link breakages. Simulation results show that, compared to non-real-time multicast techniques, RTMC can provide user-specific latency management while reducing the energy consumption in the network.
Kinetics of exchange of ions between artificial precipitation and maple leaf surfaces

SUMMARY Experiments were conducted to test the hypothesis that ion exchange between precipitation and leaves does not involve rapid transcuticular ion permeation. The kinetics of exchange of ions between artificial precipitation and sugar maple (Acer saccharum Marsh.) leaf surfaces were evaluated by measuring ion concentrations in individual drops at pH 5 4 or 3 8 after time periods on the leaf ranging from 4 to 128 min. Similar experiments were conducted in which leaves were immersed in artificial precipitation solutions. These experiments indicated that (1) mechanisms of exchange differed with ion species, (2) solution pH had significant effects on the rate of exchange, and (3) rates of ion diffusion through cuticles were small. Cu2" and Pb2+ were rapidly adsorbed to the leaf surface at pH 5*4, but not at pH 3-8. Zn2+ concentrations were unchanged by any treatment. K+, Ca2+, and Mg2+ were released from the leaf surface, and this effect was greater at pH 3 8 than pH 5*4. Apparent permeability coefficients calculated from the kinetics of these experiments indicated net exchange was dominated by cuticle surface adsorption for Cu2+ and Pb2+, and cuticular permeation for K+, Ca2+, and Mg2+. The magnitude of cuticular permeation, however, was small; calculated half-times for cation efflux from foliage were of the order of 10 days, assuming continuous precipitation. These experiments support the hypothesis that permeation of ions through cuticles during precipitation events may not occur at biologically significant rates.
Measures of Consumer Satisfaction in Social Welfare and Behavioral Health: A Systematic Review

This article reviews the origins, conceptual bases, psychometric properties, and limitations of consumer satisfaction measures in social welfare and behavioral health. Based on a systematic review ...
System identification of dynamic structures

Abstract A method is developed for determining the mass and the nonlinear stiffness and damping characteristics of structures subjected to crash-loading environments. The system identification is accomplished using adaptive time domain, constrained minimization techniques. The underlying assumptions are that the stiffness and damping characteristics of a structural element are separable and that characteristics can be idealized with piecewise linear segments. Incremental equations of motion, including error terms, are formulated and solved for nonnegative parameters using linear and quadratic programming algorithms. The parameters are estimated using three formulations: minimizing the sum of the absolute errors ( L 1 error norm), minimizing the sum of the squared errors ( L 2 error norm), and minimizing the maxium absolute error ( L ∞ error norm). Adaptivity is incorporated into the formulation for identifying discontinuities in the structural characteristics and for improving the parameter estimation. Finally, the methodology allows for the specification of upper and lower bounds for the damping forces. The motivation for this research is toward identifying the structural characteristics and developing lumped mass models of automobiles from acceleration and barrier load data collected during frontal barrier crash testing.
A new simulated annealing algorithm for the facility layout problem

In this paper we present an application of simulated annealing to facility layout problems with single and multiple floors. The facility layout problem is highly combinatorial in nature and generally exhibits many local minima. These properties make it a suitable candidate for simulated annealing. Using a new candidate layout generation routine and spacefilling curves, we develop an improvement-type layout algorithm based on simulated annealing that considers an expanded set of department exchanges. The resulting algorithm achieves low-cost solutions that are much less dependent on the initial layout than other approaches. We compare the performance of the simulated-annealing based algorithm with both steepest-descent and randomized approaches from the literature. Unlike other simulated annealing papers which typically present a statistical experiment to evaluate the effect of numerous control settings, all the experiments presented in this paper were conducted with control settings that are constant or e...
Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system.

A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.
Alcohol Use and Problem Drinking Among Male Mexican and Central American Im/migrant Laborers: A Review of the Literature

This review addresses a growing concern regarding alcohol use in adult male Latino im/migrant laborers in the United States. The review draws from alcohol studies focusing on “Hispanic” populations, and from health behavior studies of Latino im/migrant laborers, research that includes alcohol use. Specifically, this review addresses (a) alcohol consumption and drinking patterns among Mexican and Central American im/migrant laborers, and (b) health and social consequences of alcohol use. After reviewing more than 200 articles, 30 studies meeting key criteria were selected for review. Survey data show lower alcohol use in Latino im/migrants as compared with U.S. Latino and non-Latino populations, but also a relation between problem drinking and acculturation. Ethnographic research reveals heavy drinking and negative health and social consequences in a significant number of Latino im/migrant laborers. How structural-environmental and culture-based factors combine to influence problem drinking in the United S...
Fabrication of poly(α‐hydroxy acid) foam scaffolds using multiple solvent systems

The present studies describe the fabrication and characterization of highly porous and interconnected poly(alpha-hydroxy acid) foam scaffolds produced using a phase separation multisolvent system, followed by a sublimation process. Fabrication parameters, including solvent composition, polymer concentration, freezing temperature, polymer type, and polymer molecular weight, were optimized to produce the desired foam microstructure. Analyses of selected samples with scanning electron microscopic images and mercury intrusion porosimetry indicated polymer foams with pore size ranges of 100-350 microm, a porosity >90%, and an interconnecting open-pore foam structure. Scaffold degradation profiles varied according to the type and molecular weight of the polymers. Cytocompatibility assays demonstrated that the preferred foam structures were nontoxic and osteoprecursor cells seeded into the scaffolds exhibited the ability to attach, propagate, and differentiate into a calcified structure.
The effects of transformations and preliminary tests for non‐linearity in regression

Non-linear relationships between two variables are often detected as a result of a preliminary statistical test for linearity. Common approaches to dealing with non-linearity are to (a) make a linearizing transformation in the independent variable or (b) fit a relationship that is non-linear in the independent variable, such as including a quadratic term. With either approach, the resulting test for association between the two variables can have an inflated type I error. We consider testing the significance of the quadratic term in a quadratic model as a preliminary test for non-linearity. Using simulation experiments and asymptotic arguments, we quantify the type I error inflation and suggest simple modifications of standard practice to protect the size of the type I error. In the case of quadratic regression, the type I error will be increased by roughly 50 per cent. The simple strategy of appropriately correcting the alpha-level is shown to have minimal loss of power if the relationship is truly linear. In the case of a linearizing transformation, the impact on the type I error will depend on the values of the independent variable and on the set of potential linearizing transformations considered. Simulation results suggest that a procedure which adjusts the test statistic according to the results of the preliminary test may offer adequate protection.
Methylmercury: Effects on electrical properties of squid axon membranes

Abstract At low concentrations (25–100 μM) methylmercury chloride caused a steady increase in the threshold for excitation and on eventual block of action potentials without changing the resting membrane potential in squid giant axons. In the axons exposed to 25 μM methylmercury chloride, peak transient and steady-state conductances were decreased by 58.8 ± 5.1% and 35.9 ± 4.3% (mean ± SEM, 4 axons), respectively and leakage conductance increased to about five times of the control value. Higher concentrations of methylmercury chloride decreased the resting membrane potential. A concentration of 0.5 mM depolarizing the nerve membrane by 16 ± 2 mV (mean ± SEM, 3 axons) in 40 minutes. These changes in ionic conductances and membrane potential were irreversible on washing the axon with drug-free sea water.
Spatial and temporal evolution of charge carrier distributions following pulsed photoinjection

Abstract The fundamental equations governing the charge carrier dynamics in photoinsulators are solved for the configuration usually employed in drift mobility measurements. The time dependent spatial distributions of the carrier density, electric field strength and conduction current density are obtained, and these internal distributions are related to the ordinaly studied external current density.
Two topics in the physics of light nuclei

I review how tensor forces affect the ground-state structure of nuclei, and how isospin-symmetry-breaking corrections at the nucleon and nuclear level contaminate the asymmetry measured in parity-violating electron scattering from nuclei, complicating the extraction of the strange-quark form factors from these measurements.
MARKET STRUCTURE AND PROFITABILITY

The purpose of this paper is to critically examine and test the relationship between market structure and profitability in the industrial sector of the U. S. economy. The majority of empirical studies testing this relationship have found a positive but weak correlation between concentration and profitability. The basic point of contention in the literature is the explanation of why this correlation exists. The traditional or “Harvard school” interpretation of a positive correlation between profit levels and concentration across industries is that market power is associated with concentration and results in relatively higher prices than competition allows in unconcentrated industries (a price effect). A more recent hypothesis, which is associated with the Chicago school of economics, is that profitability in concentrated industries is a result of their efficiency and corresponding lower costs of production (a cost effect).
Robust modular product family design

This paper presents a modified Taguchi methodology to improve the robustness of modular product families against changes in customer requirements. The general research questions posed in this paper are: (1) How to effectively design a product family (PF) that is robust enough to accommodate future customer requirements. (2) How far into the future should designers look to design a robust product family? An example of a simplified vacuum product family is used to illustrate our methodology. In the example, customer requirements are selected as signal factors; future changes of customer requirements are selected as noise factors; an index called quality characteristic (QC) is set to evaluate the product vacuum family; and the module instance matrix (M) is selected as control factor. Initially a relation between the objective function (QC) and the control factor (M) is established, and then the feasible M space is systemically explored using a simplex method to determine the optimum M and the corresponding QC values. Next, various noise levels at different time points are introduced into the system. For each noise level, the optimal values of M and QC are computed and plotted on a QC-chart. The tunable time period of the control factor (the module matrix, M) is computed using the QC-chart. The tunable time period represents the maximum time for which a given control factor can be used to satisfy current and future customer needs. Finally, a robustness index is used to break up the tunable time period into suitable time periods that designers should consider while designing product families.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Bayesian bivariate survival estimation

There is no easy extension of the Kaplan-Meier and Nelson-Aalen estimators to the bivariate case, and estimating bivariate survival distributions nonparametrically is associated with various nontrivial problems. The Dabrowska estimator will, for example, associate negative mass to some subsets. Bayesian methods hold some promise as they will avoid the negative mass problem, but are also prone to difficulties. We simplify and extend an example by Pruitt to show that the posterior distribution from a Dirichlet process prior is inconsistent. We construct a different nonparametric prior via Beta processes and provide an updating scheme that utilizes only the most relevant parts of the likelihood, and show that this leads to a consistent estimator.
Supporting real-time multimedia traffic in a wireless LAN

The Group Allocation Multiple Access (GAMA) protocol for scheduling real-time and datagram traffic in a single- channel, single-hop, packet-radio network is specified and analyzed. By maintaining a dynamically-sized cycle that changes in length depending on the amount of network traffic, GAMA is able to provide bandwidth guarantees to the members of its 'transmission group', member stations are able to transmit real-time data at a specified rate. Each cycle contains a contention period and a group-transmission period; a station with data to send competes for the right to be added to the transmission group by successfully completing an RTS/CTS message exchange during the contention period.Once a station is a member of the transmission group, it is able to transmit a collision-free data packet during each cycle. As long as a station has data to send, it maintains its position in the group. This can be viewed as either allowing stations to 'share the floor' in an organized manner, or as establishing frames that are not synchronized on a slot-basis and vary their length dynamically based on demand. The throughput and average delay of GAMA are presented and analyzed.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Effects of Light Quality upon the Growth of Avena Coleoptiles

Summary Growth of decapitated Avena sativa coleoptile segments, of coleoptile segments which included the tip, and of coleoptiles of intact seedlings was compared in darkness and in light of different wavelengths. In all instances, both in light and in darkness, coleoptile growth in intact seedlings exceeded that of decapitated coleoptile segments, while the growth of decapitated segments was greater than that of segments which included the tip. The expansion of decapitated coleoptile segments is insensitive to light, the resulting growth being comparable to that in darkness. The growth of apical coleoptile segments is inhibited, in comparison with control segments incubated in darkness, at 510—565 nm, but stimulated at 605—700 run. Growth of the coleoptiles of intact Avena seedlings is inhibited at 455—565 nm and at 660—700 rim, though not at intermediate wavelengths.
Uncoupling the Articulation Between Girls' Education and Tradition in Tanzania

This article explores theoretical and historical problems associated with representations of gender and race in the Third World. Using a feminist cultural studies approach, the author examines representations associated with the concept of African tradition that have shaped colonial and post-colonial education policy for girls in Tanzania. Archival materials from missionary, colonial, and African sources reveal the multiple and often conflicting views of tradition conveyed through programmes intended to increase African girls' participation in school. The uses of tradition in colonial policy making are compared with its meanings in contemporary educational programmes for girls in an attempt to further feminist scholarship and action around the issue of girls' education.
Disposal of low-level radioactive wastes

The generation of low-level radioactive waste is a natural consequence of the societal uses of radioactive materials. These uses include the application of radioactive materials to the diagnosis and treatment of human disease and to research into the causes of human disease and their prevention. Currently, low level radioactive wastes are disposed of in one of three shallow land-burial disposal sites located in Washington, Nevada, and South Carolina. With the passage in December 1980 of Public Law 96-573, "The Low-Level Radioactive Waste Policy Act," the disposal of low-level wastes generated in each state was identified as a responsibility of the state. To fulfill this responsibility, states were encouraged to form interstate compacts for radioactive waste disposal. At the present time, only 37 states have entered into compact agreements, in spite of the clause in Public Law 96-573 that established January 1, 1986, as a target date for implementation of state responsibility for radioactive wastes. Recent action by Congress has resulted in postponement of the implementation date to January 1, 1993.
Narrowband filters with tightly coupled resonators

The design of narrowband combline filters implemented in double-layered microstrip is presented. The filters realise finite-frequency transmission zeros located within close proximity with respect to their passband edges. This is achieved by tightly coupling the resonators of the filters. Experimental evaluation of several fabricated filters demonstrates the principle.
GONADOTROPIC POTENCY OF THE HYPOPHYSIS IN A WILD MALE RODENT WITH ANNUAL RUT1

Does the hypophysis of male mammals with an annual sexual cycle have the capacity to exert any influence on the reproductive system except during rut? Previous assays with immature female rats as test animals have shown that the hypophysis of the male ground squirrel (Citellus tridecemlineatus) has great sex-stimulating potency during the breeding season, and suggested that it has little or no gonadotropic potency during the non-breeding period (1, 2). These assays were limited both in frequency and in decisiveness by the fact that 6 hypophyses were administered to each test rat. It was later found that a single hypophysis from a ground squirrel with spermatozoa would greatly stimulate the reproductive organs of an immature female mouse: therefore, this question has been re-investigated, using the mouse as test animal. Hypophyses of 71 male ground squirrels were tested at approximately monthly intervals during 2 annual sexual cycles, and the results are reported in this paper.2
Neuropsychiatric Complications Associated With Interferon-Alpha-2b Treatment of Malignant Melanoma

Received July 2, 2001; revised November 13, 2001; accepted December 7, 2001. From the Department of Psychiatry, Massachusetts General Hospital. Address reprint requests to Dr. Okereke, Massachusetts General Hospital, Wang BuildingSuite 812, Boston, MA 02114. Malignant melanoma is a common skin neoplasm; it accounts for 3% of all cancers.1 Each year, approximately 40,000 new cases are diagnosed in the United States. Treatments for this potentially lethal cancer include lesion excision, lymph node dissection, and surgical adjuvant therapy with chemotherapy or with an immunomodulatory agent.1 More recently, interferon-alpha-2b (IFN-A), an immunomodulatory drug produced by recombinant DNA techniques, has become the agent of choice for patients with resected lesions and a high risk of disease recurrence.2,3 Unfortunately, a variety of neuropsychiatric side effects can result from use of IFN-A. This is the case of a 51-year-old man who underwent a course of high-dose intravenous (IV) IFN-A to treat malignant melanoma. During IFN-A therapy, he developed severe depression, which was effectively treated with electroconvulsive therapy (ECT). To the author’s knowledge, this is the first such case report. A review of the relevant literature on malignant melanoma, IFN-A, and interferon-related mood disorders and their treatments is provided.
Hysteroscopic Removal of Cervical Ectopic Pregnancy Following Failed Intramuscular/Intra-Sac Methotrexate: A Case Report

Abstract Background: Cervical pregnancy is a diagnosis associated with significant morbidity, specifically life-threatening hemorrhage that potentially requires hysterectomy to prevent maternal death. Conservative and fertility-sparing management strategies are poorly described in the literature, and there is no clear standard of care. Case: The patient was a 34-year-old gravida 1, para 0 who had conceived spontaneously after laparoscopic treatment of endometriosis, and was found to have cervical pregnancy. She received both intramuscular and intra-sac methotrexate, with no resolution of the ectopic pregnancy. The pregnancy was removed hysteroscopically. Results: Subsequently, the patient was able to achieve a normal clinical pregnancy with ovulation induction/intrauterine insemination. This pregnancy was carried to term. Conclusions: Although cervical pregnancy is particularly hazardous and potentially fatal, conservative/fertility-sparing management of these pregnancies can be successful. (J GYNECOL SUR...
Lope de Vega, 1562–1635

IN August, 1935, Spain will commemorate the three hundredth anniversary of the death of Lope de Vega. To the average reader outside of Spain, the name of Cervantes as creator of Don Quixote and Sancho Panza is undoubtedly familiar; the mention of his famous compatriot, Lope de Vega, is not likely to find a similar response. Any allusion to the foremost Spanish playwright will hardly conjure up the title of a famous work or recall a noteworthy character of his invention. His name has become synonymous rather with that of the miracle author, of the superman who composed uncounted hundreds of plays, which were only a portion of his uncanny output in poetry and prose. In fact, even in brief histories of literature his reputation is described so as to leave the impression that it is based upon a prodigious feat of production rather than upon the positive achievement of definite well-known works. No doubt Lope brought this fate upon himself during his own lifetime, when he was already known as the "monster of nature"; and thereafter some of his eulogizers, who took pleasure in informing the reader, not about his special claim to renown, but about the unbelievable millions of verses which he composed stans pede in uno, confirmed the impression. No such fluent improvisor as Lope can be found in any other age or literature. Although only about one-fourth of his entire production has survived, if we are to put absolute trust in his own words and fantastic figures, the remnant would fill a shelf long enough to compete with Dr. Eliot's collection of world-literature. His miscellaneous works furnish sufficient reading material for the rest of our natural lives, and the contents will be analyzed and picked over for possible thesis-subjects as long as this academic tradition survives.
All-optical switching at ultralow light levels

We report an experimental demonstration of all-optical switching at ultralow light levels in coherently prepared Rb atoms. A signal light pulse is switched on and off by a control light pulse at different frequencies in a four-level atomic system based on multiphoton interferences. We observed a switching efficiency of 55% with the signal and control light pulses containing approximately 20 photons each, corresponding to a control energy density of approximately 10(-5) photons per atomic cross section lambda(2)/(2pi).
Inactivation of hepatic enzymes by inhalant nitrite--in vivo and in vitro studies.

We examined the effects of acute isobutyl nitrite (ISBN) exposure on the activity of several hepatic enzymes. Two strains of adult male mice (Balb/c and C57BL/6) were exposed to 900 ppm ISBN or ambient air for 45 minutes. The enzyme activity of hepatic cytochrome P450 (CYP)-mediated deethylation, glutathione S-transferase (GST), and carboxylesterase (CBE) was monitored through the substrates 3-cyano-7-ethoxycoumarin (CEC), 1-chloro-2,4-dinitrobenzene, and p-nitrophenyl acetate, respectively. Acute ISBN exposure led to a significant reduction in hepatic CYP-mediated CEC deethylation, GST, and CBE activity in Balb/c mice (of 81.5%, 74.7%, and 25.2%, respectively, vs control mice, each at P<.05) when livers were harvested immediately after inhalant exposure. The corresponding decreases in C57BL/6 mice were smaller (with reductions of 21.8%, 18.8%, and 13.3%, respectively, each at P<.05). This enzyme activity, tested in C57BL/6 mice only, returned to control values after a 24-hour period of nonexposure. Follow-up mechanistic investigations using rat liver GST indicated that ISBN-mediated enzyme inactivation was not caused by its metabolites: inorganic nitrite ion (NO2−) or nitric oxide. This inactivation could be prevented, but not reversed, by added glutathione, suggesting irreversible protein oxidation. Using different NO donors as comparative agents, we found that GST inactivation by ISBN was not associated with protein S-nitrosylation or disulfide formation, but with tyrosine nitration. Inhalant nitrite exposure, therefore, led to a significant reduction in hepatic enzyme activity in mice, possibly through tyrosine nitration of hepatic proteins. This effect raises the possibility of drug-drug metabolic interactions from inhalant nitrite abuse. However, determining the applicability of these findings to humans will require further study.
MODELING THE ASSOCIATION OF PETROLEUM HYDROCARBONS AND SUB-ARCTIC SEDIMENTS

ABSTRACT The extent of association between labeled hydrocarbons representing the major chemical classes of petroleum, and marine suspended sediments from south-central Alaska has been investigated in a series of laboratory experiments using hydrocarbon concentrations near or below saturated solution. For a saturated solution of either an aliphatic or aromatic hydrocarbon, the concentration of hydrocarbon in parts per million (ppm) associated with sediment is roughly 30 percent of the original aqueous concentration in ppm. Extrapolation of these results to permitted discharge concentrations and dilution rates encountered in south-central Alaska indicates that concentrations of hydrocarbons sorbed to sediments are in the parts per trillion (ppt) to parts per billion (ppb) range. It appears that this process cannot be a major transport pathway for the dispersal of oil under the conditions investigated.
A new wild potato mutant in Solanum stoloniferum Schltdl. Lacking purple pigment

A sample ofSolanum stoloniferum Schltdl. (reclassified fromSolanum fendleri A. Gray), PI 620874, was collected by the authors from a previously undocumented site in the Patagonia Mountains of southern Arizona in September 2001. When original seed was grown at the US Potato Genebank, two of 25 seedlings produced white flowers. Upon closer inspection they were found to be completely without purple pigmentation on the tubers, stems, and underside of leaves—a characteristic previously unknown in this species and rare in wild potato overall.Solanum stoloniferum, like other species of series Longipedicellata (LON), is a disomic tetraploid. Results of crossing trials were consistent with the most simple genetic explanation for this phenotype: a recessivep allele at the P locus, making the mutant (pp pp), or “Purple-less” abbreviated “P-less.” P-less plants were testcrossed with nearly 200 other LON populations originating across the U.S.A. and Mexico to make BC1 generations that had either one-half or one-quarter P-less seedlings. Surprisingly, about one-third of the populations, and from widely distributed origins, produced one-half P-less progeny, indicating that they also possess the recessive allele on one genome. Since this mutant has not been confirmed as an allele at the original P locus, its designation with the same allele symbols in this report (P andp) is provisional. This discovery of the widespreadp allele in LON and P-less mutants could provide a simple, unambiguous seedling marker for study of gene flow and dispersion, pollinator behavior in the wild, gene expression interactions between homeologous genomes, and chromosome pairing control.
150 Gsample/s wavelength division sampler with time-stretched output

A new technique for optical sampling and time stretching of an analogue signal is presented. The signal is ‘wavelength stamped’ by a chirped optical pulse. An arrayed waveguide grating provides parallel time-interleaved samples as well as a time-stretched serial sampled waveform.
Improved neuromagnetic detection of fetal and neonatal auditory evoked responses

Abstract Objective : To assess the quality of fetal and neonatal auditory evoked responses (fAERs and nAERs) obtainable with a low-noise, high-channel count SQUID gradiometer in a well-shielded environment. Methods : Measurement of long-latency fAERs was attempted in 19 normal fetuses in 28 sessions at 29–40 weeks’ gestation, using a 37-channel SQUID gradiometer. Postnatal measurement was attempted in 16 neonates in 25 sessions at age 2–6 weeks. Results : Signals of amplitude 8 fT or greater were detected in 15 of 28 fetal measurement sessions, yielding a higher success rate (54%) than in a previous study of ours. Signals of amplitude greater than 25 fT were detected in 23 of 25 (92%) of neonatal measurement sessions. The spatial and temporal characteristics of the signals were studied in greater detail. Dipole patterns consistent with a source in the auditory cortex were observable in nearly all neonates and in many fetuses. The dominant component of the nAER was compatible with the P250 seen in neonatal EEG recordings; however, the largest component of the fAERs had longer latency and in many subjects had opposite polarity. Conclusion : A higher success rate, earlier detection, and improved characterization of signal morphology and topography were demonstrated for fAER recordings.
Do calcium channel blockers protect against renal ischemia

Data from several studies have indicated that calcium channel blockers may prevent acute renal damage caused by ischemia. If this is true, then the obvious clinical application of this premise would b
Disassembly Planning and Timing Through a Petri Net Approach

Disassembly planning and costing is a major task in the achievement of sustainable manufacturing. This paper presents a systematic approach to identify the feasible ways to disassemble a product then to select the most economical one using reliable time data gathered from experimental and practice-oriented sources. The disassembly process is modeled after the Petri Net approach, a technique that has proven to be fairly popular with the research community in the last few decades. The result of our systematic approach is a reliable derivation for a time-effective disassembly plan.Copyright © 2008 by ASME
901-50 Non-doppler Three Dimensional Flow Images Obtained via Reconstruction from 2D Vector Velocity Maps

We describe a method for producing three dimensional images of flow magnitude and direction. The method involves the use of an ultrasonic vector velocity speckle tracking system which computes 2D flow velocity maps in real time. This system, unlike Current Doppler instrumentation, quantifies both the axial and lateral components of flow velocity vectors and thereby requires no angle correction. Numerous velocity maps are obtained for successive, closely spaced parallel planes by translating the ultrasound transducer across the flow region of interest. These 2D velocity maps are processed via commercial graphics software to yield three dimensional images showing the magnitudes and directions of flow throughout the interrogated volume. We present images from in vitro experiments with a jet phantom and a 4 mm vessel surrounded by tissue mimicking material. Constant-velocity surfaces obtained from the jet phantom allow visualization of the characteristic high velocity central core, surrounded by cones of lower velocities farther from the jet centerline. Directional arrows superimposed on images of the 4 mm vessel allow visualization of the three dimensional flow velocity profile. Results indicate the promise of this technique for improved visualization and absolute quantification of cardiac flow in an angle independent fashion.
Durability of vein graft revision: the outcome of secondary procedures.

Abstract Occlusive lesions that reduced graft blood flow and ankle systolic pressure were identified in 83 femorodistal saphenous vein bypasses by use of duplex scanning or arteriography. Sites of stenosis included vein conduit ( n = 41), anastomoses ( n = 20), outflow arteries ( n = 15), or inflow ( n = 9) arteries. One hundred three secondary procedures consisting of vein-patch angioplasty ( n = 31), sequential ( n = 21) or interposition ( n = 17) graft placement, percutaneous transluminal balloon angioplasty ( n = 17), or excision of the lesion and primary anastomosis ( n = 16) were performed to correct primary ( n = 85) or recurrent ( n = 18) graft stenoses. Cumulative graft patency after reintervention was 96% at 1 year, and 85% at 5 years. Stenosis or occlusion of revision sites was less after excision (0 of 16) or replacement (1 of 17) of abnormal segments compared to vein-patch angioplasty (8 of 31) or balloon angioplasty (9 of 18). Sequential or jump grafts constructed to improve graft outflow impaired by either myointimal or atherosclerotic occlusive lesions were the least durable secondary procedures. Five of eight graft failures in this series resulted from sequential/jump graft occlusion. All categories of secondary procedures normalized graft and limb hemodynamics, although only one third of patients reported symptoms of limb ischemia before revision. Surveillance of infrainguinal vein bypasses for occlusive lesions is a valid concept to salvage patent but hemodynamically-failing grafts. Secondary procedures that excised the lesion, used autologous tissue reconstruction, and normalized hemodynamics at the revision site and in the vein bypass were associated with a low incidence of restenosis and prolonged graft patency. (J VASC SURG 1991;13:200-10.)
Quantitative link between single-particle dynamics and static structure of supercooled liquids

We present evidence via molecular simulation that the supercooled fluid states of SPC/E water as well as the "repulsive" and "attractive" supercooled fluid states of a recently introduced model for colloids with short-ranged attractions are characterized by the same functional relationship between self-diffusivity and the pair correlation function. We discuss how this simple relationship connects to an earlier finding that the temperature dependency of a supercooled fluid's single-particle dynamics tracks that of its excess entropy (relative to ideal gas). The generality of this observed structure-property relationship is supported by its ability to successfully describe the nontrivial behaviors of these very different types of model systems.
Effect of geometric and motion tracking error for awake small animal SPECT

A series of simulation studies were performed to evaluate the effects of geometric and motion tracking errors on reconstruction image quality for a single pinhole collimator awake animal imaging SPECT system. List-mode SPECT data generated using a custom Monte Carlo program that incorporated experimental mouse motion data were reconstructed by MLEM with Siddon's ray tracing. To better understand the impact of motion tracking and system geometric parameter errors on reconstructed system data, an offset of up to 1 mm or degree was separately applied to each for evaluation. In the absence of motion tracking or system geometric error, the applied motion compensation algorithm successfully reconstructed volumes without any degradation or distortion. Presented results reveal that motion tracking errors propagate through the SPECT reconstruction process. However, it is confirmed that the impact of tracking errors in the currently employed motion tracking system, is minimal because of their accuracy. The results also reveal the direct and indirect impact of geometric errors to motion compensated reconstruction quality and that a wrong assumption of pinhole transaxial position produces the most amount of distortion of all the investigated errors. Finally, system geometric errors are shown to have a greater impact on reconstruction quality than equivalent tracking errors.
Maternal Cigarette Smoking, Regular Use of Multivitamin/Mineral Supplements, and Risk of Fetal Death: The 1988 National Maternal and Infant Health Survey

Data from the 1988 National Maternal and Infant Health Survey were used to examine whether regular use of multivitamin/mineral supplements could modify the relation between maternal smoking and fetal death. Maternal smoking was defined as the self-reported average number of cigarettes smoked after recognition of pregnancy. Regular supplement use was defined as use of multivitamin/mineral supplements for at least 3 days per week during the 3 months before and/or after recognition of pregnancy. The sample comprises 12,465 singleton pregnancies, including 9,402 livebirths and 3,063 fetal deaths. Odds ratios were derived from logistic regression analyses after adjustment for a number of demographic and reproductive variables. Major findings are that 1) smoking increased the risk of fetal death; 2) regular supplement use either before or after recognition of pregnancy did not affect the risk of fetal death in the absence of maternal smoking; 3) odds ratios for fetal death among smoking women who regularly used supplements were generally smaller than those for women who did not regularly use supplements but who smoked a comparable number of cigarettes; and 4) a significant negative excess risk due to interaction was observed among women who regularly used supplements before recognition of pregnancy and smoked 20 or more cigarettes a day. These findings suggested that regular multivitamin/mineral supplement use might reduce the risk of fetal death associated with maternal smoking.