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Showing papers by "University of Wisconsin-Madison published in 1986"


Posted Content
TL;DR: In this article, a simple method of calculating a heteroskedasticity and autocorrelation consistent covariance matrix that is positive semi-definite by construction is described.
Abstract: This paper describes a simple method of calculating a heteroskedasticity and autocorrelation consistent covariance matrix that is positive semi-definite by construction. It also establishes consistency of the estimated covariance matrix under fairly general conditions.

5,822 citations


Book
01 Jul 1986
TL;DR: The mountain pass theorem and its application in Hamiltonian systems can be found in this paper, where the saddle point theorem is extended to the case of symmetric functionals with symmetries and index theorems.
Abstract: An overview The mountain pass theorem and some applications Some variants of the mountain pass theorem The saddle point theorem Some generalizations of the mountain pass theorem Applications to Hamiltonian systems Functionals with symmetries and index theorems Multiple critical points of symmetric functionals: problems with constraints Multiple critical points of symmetric functionals: the unconstrained case Pertubations from symmetry Variational methods in bifurcation theory.

3,685 citations


Journal ArticleDOI
TL;DR: For most boys and girls, the transition from childhood into adolescence is marked more by a trading of dependency on parents for dependency on peers, rather than straightforward and unidimensional growth in autonomy as mentioned in this paper.
Abstract: A sample of 865 10-16-year-olds from a range of socioeconomic backgrounds completed a questionnaire battery concerning 3 aspects of autonomy: emotional autonomy in relationship with parents, resistance to peer pressure, and the subjective sense of self-reliance. The observed patterns of relations among the measures cast doubt on the notion that autonomy is a unidimensional trait manifested similarly across a variety of situations. For most boys and girls, the transition from childhood into adolescence is marked more by a trading of dependency on parents for dependency on peers, rather than straightforward and unidimensional growth in autonomy. Moreover, contrary to long-standing notions about the greater salience of autonomy to adolescent males than to females, girls score higher than boys on all 3 measures of autonomy at all age levels.

1,187 citations


Journal ArticleDOI
TL;DR: A procedure to obtain high and repeatable fertilization frequencies for bovine in vitro fertilization (IVF) with frozen-thawed sperm was developed and Heparin was the most important factor in increasing IVF frequencies.

1,165 citations


Journal ArticleDOI
TL;DR: The authors used the Community Climate Model (CCM) of the National Center for Atmospheric Research (NCAR) to estimate the magnitude, timing and pattern of the climatic response to prescribed changes of orbital parameters (date of perihelion, axial tilt, eccentricity) and glacial-age lower boundary conditions (ice sheets, land albedo, sea ice and sea surface temperature).
Abstract: General circulation model experiments at 3000-year intervals for the past 18 000 years were made to estimate the magnitude, timing, and pattern of the climatic response to prescribed changes of orbital parameters (date of perihelion, axial tilt, eccentricity) and glacial-age lower boundary conditions (ice sheets, land albedo, sea ice and sea surface temperature). The experiments used the Community Climate Model (CCM) of the National Center for Atmospheric Research (NCAR). The response of monsoon circulations and tropical precipitation to the orbitally produced solar radiation changes was much larger than the response to changes of glacial-age boundary conditions. The continental interior of Eurasia was 2–4 K warmer in summer, and summer monsoon precipitation of North Africa-South Asia was increased by 10–20% between 12 000 and 6000 yr BP (before present) when perihelion occurred during northern summer (rather than in winter as now) and the earth's axial tilt was larger than now. Southern Hemisphe...

1,138 citations


Journal ArticleDOI
TL;DR: This work implemented and tested a final real-time QRS detection algorithm, using the optimized decision rule process, which has a sensitivity of 99.69 percent and positive predictivity of 98.77 percent when evaluated with the MIT/BIH arrhythmia database.
Abstract: We have investigated the quantitative effects of a number of common elements of QRS detection rules using the MIT/BIH arrhythmia database. A previously developed linear and nonlinear filtering scheme was used to provide input to the QRS detector decision section. We used the filtering to preprocess the database. This yielded a set of event vectors produced from QRS complexes and noise. After this preprocessing, we tested different decision rules on the event vectors. This step was carried out at processing speeds up to 100 times faster than real time. The role of the decision rule section is to discriminate the QRS events from the noise events. We started by optimizing a simple decision rule. Then we developed a progressively more complex decision process for QRS detection by adding new detection rules. We implemented and tested a final real-time QRS detection algorithm, using the optimized decision rule process. The resulting QRS detection algorithm has a sensitivity of 99.69 percent and positive predictivity of 99.77 percent when evaluated with the MIT/BIH arrhythmia database.

1,137 citations


Journal ArticleDOI
TL;DR: In this article, the form of the conditional quantiles for the censored regression models is heuristically derived and discussed, and the resulting estimators of the regression coefficients, which include the censored LAD estimator as a special case, are shown to be consistent and asymptotically normally distributed under appropriately translated versions of the corresponding assumptions for the former approach.

837 citations


Journal ArticleDOI
TL;DR: The efficacy of antihistamine therapy, the allergic-like symptomology, and the finding of high levels of histamine in the implicated food suggest strongly that histamine is the causative agent, however, histamines ingested with spoiled fish appears to be much more toxic than histamine ingested in an aqueous solution.
Abstract: Histamine poisoning can result from the ingestion of food containing unusually high levels of histamine. Fish are most commonly involved in incidents of histamine poisoning, although cheese has also been implicated on occasion. The historic involvement of tuna and mackerel in histamine poisoning led to the longtime usage of the term, scombroid fish poisoning, to describe this food-borne illness. Histamine poisoning is characterized by a short incubation period, a short duration, and symptoms resembling those associated with allergic reactions. The evidence supporting the role of histamine as the causative agent is compelling. The efficacy of antihistamine therapy, the allergic-like symptomology, and the finding of high levels of histamine in the implicated food suggest strongly that histamine is the causative agent. However, histamine ingested with spoiled fish appears to be much more toxic than histamine ingested in an aqueous solution. The presence of potentiators of histamine toxicity in the spoiled fish may account for this difference in toxicity. Several potentiators including other putrefactive amines such as putrescine and cadaverine have been identified. Pharmacologic potentiators may also exist; aminoguanidine and isoniazid are examples. The mechanism of action of these potentiators appears to be the inhibition of intestinal histamine-metabolizing enzymes. This enzyme inhibition causes a decrease in histamine detoxification in the intestinal mucosa and results in increased intestinal uptake and urinary excretion of unmetabolized histamine.

681 citations


Journal ArticleDOI
TL;DR: This paper presents a comparative study and survey of model-based object-recognition algorithms for robot vision, and an evaluation and comparison of existing industrial part- recognition systems and algorithms is given, providing insights for progress toward future robot vision systems.
Abstract: This paper presents a comparative study and survey of model-based object-recognition algorithms for robot vision. The goal of these algorithms is to recognize the identity, position, and orientation of randomly oriented industrial parts. In one form this is commonly referred to as the "bin-picking" problem, in which the parts to be recognized are presented in a jumbled bin. The paper is organized according to 2-D, 2½-D, and 3-D object representations, which are used as the basis for the recognition algorithms. Three central issues common to each category, namely, feature extraction, modeling, and matching, are examined in detail. An evaluation and comparison of existing industrial part-recognition systems and algorithms is given, providing insights for progress toward future robot vision systems.

656 citations


Journal ArticleDOI
TL;DR: Chinese adults literate only in Chinese characters could not add or delete individual consonants in spoken Chinese words, but a comparable group of adults, literate in alphabetic spelling as well as characters, could perform the same tasks readily and accurately.

643 citations


Journal ArticleDOI
TL;DR: In this article, the authors discuss reactions des polymeres de polysilane, photochimie et scission, reticulation des polysilanes, applications technologiques des poly(diorganosilylenes)

Journal ArticleDOI
TL;DR: Findings corroborate earlier findings that psychopaths are relatively poor at learning to inhibit reward-seeking behavior that results in monetary punishment.
Abstract: Research on passive avoidance learning has demonstrated reliabledifferences between psychopaths and controls when avoidance errors result in electric shock but not in loss of money (Schmauk, 1970). Using monetary punishments, Newman, Widom, and Nathan (1985) found that psychopathic delinquents performed more poorly than controls in an experimental paradigm employing monetary reward as well as the avoidance contingency. The present study was conducted to replicate and extend these findings using adult psychopaths and a computer controlled task. Sixty white male prisoners were assigned to groups using Hare's (1980) Psychopathy Checklist and administered a "go/no-go" discrimination task involving monetary incentives. One condition entailed competing reward and punishment contingencies; the other, two punishment contingencies. As predicted, psychopaths made significantly more passive avoidance errors than nonpsychopaths when the task conmined competing goals (/9 < .05) but performed as well as controls when the subjects' only goal was avoiding punishment. Results corroborate earlier findings that psychopaths are relatively poor at learning to inhibit reward-seeking behavior that results in monetary punishment.

Book ChapterDOI
TL;DR: A survey on the economics of labor market discrimination, motivated by two fundamental problems associated with income and wage differences among groups classified by sex, race, ethnicity, and other characteristics is presented in this article.
Abstract: Publisher Summary The chapter presents a survey on the economics of labor market discrimination, motivated by two fundamental problems associated with income and wage differences among groups classified by sex, race, ethnicity, and other characteristics. The first is the inequity of long-lasting differences in economic well-being among the groups; in particular, differences in household or family income. The second is the inequity of long-lasting differences in the average wage rates among groups of workers classified by these demographic traits, when the groups may be presumed to be either equally productive or to have equal productive capacity. The second problem also raises the question of whether a labor market that pays unequal wages to equally productive workers is inefficient. Economic discrimination is defined in terms of income differences among families and wage differences among workers. The chapter discusses these definitions and presents data from the United States on the income and earnings differences of blacks, Hispanics, whites, women, and men. The chapter surveys theories of economic discrimination in the labor market. The theories are classified into competitive and monopolistic neoclassical models with (essentially) complete information, competitive neoclassical models with imperfect information-leading to “statistical discrimination,” and institutional theories. The chapter concludes with a discussion of the policy implications of the economic research on discrimination.

Journal ArticleDOI
TL;DR: Chez deux echantillons d'adolescents des grades 6 a 12 sont etudiees les dispositions a acceder a la pression des pairs, les perceptions de cette pression and les auto-appreciations de la frequence des comportements lies au degre de socialisation avec les amis et aux mauvaises conduites as discussed by the authors.
Abstract: Chez deux echantillons d'adolescents des grades 6 a 12 sont etudiees les dispositions a acceder a la pression des pairs, les perceptions de cette pression et les auto-appreciations de la frequence des comportements lies au degre de socialisation avec les amis et aux mauvaises conduites

Journal ArticleDOI
11 Apr 1986-Cell
TL;DR: The synthetic peptide VGIDLGTTYSC, derived from the heat shock-induced genes human hsp70, Drosophila hsp 70, S. cerevisiae YG100, and E. coli dnaK, elicited antibodies that recognized two constitutive proteins in bovine extracts that show that uncoating ATPase is a member of the 70 kd heat shock protein family.

Journal ArticleDOI
TL;DR: A more formal analysis is presented here, which may be used to supplement such plots and hence to facilitate the use of these unreplicated experimental arrangements.
Abstract: Loss of markets to Japan has recently caused attention to return to the enormous potential that experimental design possesses for the improvement of product design, for the improvement of the manufacturing process, and hence for improvement of overall product quality. In the screening stage of industrial experimentation it is frequently true that the “Pareto Principle” applies; that is, a large proportion of process variation is associated with a small proportion of the process variables. In such circumstances of “factor sparsity,” unreplicated fractional designs and other orthogonal arrays have frequently been effective when used as a screen for isolating preponderant factors. A useful graphical analysis due to Daniel (1959) employs normal probability plotting. A more formal analysis is presented here, which may be used to supplement such plots and hence to facilitate the use of these unreplicated experimental arrangements.

Journal ArticleDOI
01 Dec 1986-Nature
TL;DR: In this paper, the authors propose that deformation within the till is the primary mechanism by which the ice stream moves, and discuss implications of this hypothesis, and assume that this thin layer occurs well inland beneath an active ice sheet and rests on a surface showing flutes characteristic of glacial erosion.
Abstract: The behaviour and possible instability of the West Antarctic ice sheet depend fundamentally on the dynamics of the large ice streams which drain it. Model calculations show that most ice-stream velocity arises at the bed1,2, and radar sounding has shown the bed to be wet3, but the basal boundary condition is not well understood. Seismic evidence from the Upstream B camp (UpB) on the Siple Coast of West Antarctica4 shows that the ice stream there rests on a layer of unconsolidated sediment averaging 5 or 6 m thick, in which the water pressure is only ∼50 kPa less than the overburden pressure. Because this thin layer occurs well inland beneath an active ice sheet and rests on a surface showing flutes4 characteristic of glacial erosion5, we presume that it is glacial till. We propose here that deformation within the till is the primary mechanism by which the ice stream moves, and we discuss implications of this hypothesis.


Journal ArticleDOI
TL;DR: The concept of "habit" was long a staple term in the conceptual vocabulary of Western social theorists and continued to function as a major background factor in the substantive writings of both Emile Durkheim and Max Weber as discussed by the authors.
Abstract: This article is a historical investigation of the concept of habit in sociology. Beginning with the claim that historians of sociology need to look beyond the now-famous ideas that appear in the foreground of the works of the sociological masters, the article examines the neglected idea of habit to document that this concept was long a staple term in the conceptual vocabulary of Western social theorists and that it continued to function as a major background factor in the substantive writings of both Emile Durkheim and Max Weber-a factor that previous scholarship on Durkheim and Weber has almost completely overlooked. It is shown that Durkheim viewed habit not only as a chief determinant of human action in a great variety of areas but also as one of the principal supports for the moral fabric of modern societies. Similarly, habit is found to be significant in Weber's treatment of modern economic and political life, Calvinism and the spirit of capitalism, and the force of traditionalism, which is so centra...

Journal ArticleDOI
TL;DR: The authors' data favor 2 primary areas of domestication, one in Middle America leading to small-seeded cultivars with ‘S’ phaseolin patterns and the other in the Andes giving rise to large-seeding cultivarsWith ‘T’ (and possibly ‘C,’ ‘H,” and ‘A’) phaseolinpatterns.
Abstract: A sample of 106 wild forms and 99 landraces of common bean (Thaseolus vulgaris) from Middle America and the Andean region of South America were screened for variability in phaseolin seed protein using one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE) and two-dimensional isoelectric focusing SDS/PAGE. The Middle American wild forms exhibited phaseolin patterns similar to the ‘S’ pattern described previously in cultivated forms, as well as a wide variety of additional banding patterns—‘M’ (Middle America) types—not encountered among common bean cultivars. The Andean wild forms showed only the ‘T’ phaseolin pattern, also described previously among cultivated forms. Landraces from Middle America showed ‘S’ or ‘S’-like patterns with the exception of 2 lines with ‘T’ phaseolin. In Andean South America, a majority of landraces had the ‘T’ phaseolin. Additional types represented in that region were (in decreasing order of frequency) the ‘S’ and ‘C’ types (already described among cultivated forms) as well as the ‘H’ (Huevo de huanchaco) and ‘A’ (Ayacucho), (new patterns previously undescribed among wild and cultivated beans). In each region—Middle America and Andean South America—the seeds of landraces with ‘T’ phaseolin were significantly larger than those of landraces with ‘S’ phaseolin. No significant differences in seed size were observed among landraces with ‘T,’ ‘C,’ ‘H,’ and ‘A’ phaseolin types of the Andean region. Our data favor 2 primary areas of domestication, one in Middle America leading to small-seeded cultivars with ‘S’ phaseolin patterns and the other in the Andes giving rise to large-seeded cultivars with ‘T’ (and possibly ‘C,’ ‘H,’ and ‘A’) phaseolin patterns.

Journal ArticleDOI
TL;DR: The evaluation of a prototype dual-energy implementation using rapid kVp switching on a clinical computed tomographic scanner is reported, which employs prereconstruction basis material decomposition of the dual- energy projection data.
Abstract: We report the evaluation of a prototype dual-energy implementation using rapid kVp switching on a clinical computed tomographic scanner. The method employs prereconstruction basis material decomposition of the dual-energy projection data. Each dual-energy scan can be processed into conventional single-kVp images, basis material density images, and monoenergetic images. Phantom studies were carried out to qualitatively and quantitatively evaluate and validate the approach.

Journal ArticleDOI
TL;DR: There is a higher rate of modest visual improvement and a lower rate of visual deterioration in eyes treated with laser photocoagulation, and Correction of systemic abnormalities (reduced blood pressure, diuresis) should be included as part of the total management of patients with diabetic macular edema.

01 Jan 1986
TL;DR: This work conceive of urges as affects, whose activation mediates drug pursuit and self-administration, and believes that affects are represented in neural networks comprising information on affect-relevant stimuli, responses, and meaning/expectancy.
Abstract: Traditionally, theories of addiction have stressed that drug urges are characterized by dysphoria, occur in response to decreasing levels of drug or drug effect, and are associated with withdrawal symptoms/signs or drug-antagonistic responses arising from a homeostatic mechanism. However, recent research has shown that urges, drug self-administration, and relapse all occur concomitant with both positive and negative affect, rising and falling levels of drug, and with drug-agonistic responses, as well as antagonistic/withdrawal responses. In keeping with recent theorizing about motivation and emotions, we believe that affective responding provides a readout of the motivational status of an organism (e.g., Buck, 1985). We conceive of urges as affects, whose activation mediates drug pursuit and self-administration. Moreover, we believe that affects are represented in neural networks comprising information on affect-relevant stimuli, responses, and meaning/expectancy. We believe that there are two types of urge networks. One, a "positive-affect" network, is activated, associatively and nonassociatively, by appetitive stimuli, especially appetitive drug actions that activate "GO" motivational incentive systems. Activation of this network is characterized by positive affect, drug isodirectional responding, attentional focus on a dominant response, and enhanced pursuit of appetitive stimuli--especially the drug. The operating characteristics of the positive-affect network, and the associated motivational systems, result in a drug's instating a positive feedback loop. Appetitive drug actions increase the likelihood of the pursuit of appetitive stimuli, and additional drug constitutes a prepotent candidate from among the available appetitive stimuli. This positive feedback loop may account in part for cardinal features of addiction: for example, the great relapse likelihood once any drug is sampled, the attainment of very high blood levels of a drug, and the pursuit of adjunctive appetitive stimuli while using a drug. The second type of urge network we have labeled a "negative-affect" network, and we believe it is activated, associatively and nonassociatively, by inappetitive stimuli or consequences (punishment, signals of punishment, frustrating lack of reward, etc.) and by withdrawal and signals of withdrawal (e.g., drug cues, which during the course of addiction are associated with both direct drug effects and withdrawal). Activation of the network is characterized by withdrawal symptoms and signs, negative affect, and drug seeking.(ABSTRACT TRUNCATED AT 400 WORDS)

Journal ArticleDOI
TL;DR: In this paper, a conceptual clarification of the sources and meaning of cross-sectional price variability is used to motivate a theoretical and econometric framework for the estimation of crosssectional demand functions.
Abstract: A conceptual clarification of the sources and meaning of cross-sectional price variability is used to motivate a theoretical and econometric framework for the estimation of cross-sectional demand functions. Quality effects are distinguished from supply-related price variability to identify cross-sectional demand for disaggregated food commodities. An empirical application using data from the 1977-78 Nationwide Food Consumption Survey indicates that parameter differences resulting from a failure to adjust cross-sectional prices for quality effects are likely to be small for relatively homogenous, disaggregated food commodities. In demand analysis with cross-sectional, household budget data, it is usually assumed that prices are constant (Allen and Bowley, Prais and Houthakker, George and King). Given this assumption, Engel functions are estimated where expenditure (or quantity) is regressed on income (or total expenditures), family size, and other demographic characteristics. The assumption that cross-sectional price effects are absent or are captured adequately by spatial and temporal dummy variables has not been evaluated empirically. Whether cross-sectional price effects can be treated in this manner has implications for the specification of cross-sectional demand functions as well as the estimation of Engel functions. There is a considerable literature on estimating price elasticities with cross-sectional data. Most of the applications utilize timeseries/cross-sectional data. Annual (or quarterly) household consumption surveys and

Journal ArticleDOI
09 May 1986-Science
TL;DR: HIV-1 RNA load testing is sometimes requested to resolve equivocal serologic findings or to facilitate the diagnosis of HIV-1 infection during the acute phase or in a pediatric setting.
Abstract: The human immunodeficiency virus (HIV) is the etiologic agent of AIDS. HIVs are enveloped plus-stranded RNA viruses. The HIV genome is organized similarly to other retroviruses. It contains the gag, pol, and env genes which encode structural proteins, viral enzymes, and envelope glycoproteins, respectively. The major structural proteins which are encoded by the gag gene include p17, p24, p7, and p9. Replication begins with the attachment of virus to the target cell via the interaction of gp120 and the cellular receptor CD4. Both HIV-1 and HIV-2 have the same modes of transmission. The most common mode of HIV infection is sexual transmission at the genital mucosa through direct contact with infected blood fluids, including blood, semen, and vaginal secretions. Serological testing for HIV antibody is used for various purposes, including primary diagnosis, screening of blood products, management of untested persons in labor and delivery, evaluation of occupational exposures to blood/body fluid, and epidemiological surveillance. The first generation of HIV antibody assays relied on the detection of antibody to HIV viral protein lysates. A test using a sandwich-capture format and significantly more blood than other methods was more sensitive in early seroconversion. HIV-1 RNA load testing is sometimes requested to resolve equivocal serologic findings or to facilitate the diagnosis of HIV-1 infection during the acute phase or in a pediatric setting.

Journal ArticleDOI
TL;DR: This paper examined the deterrent effect of formal sanctions on criminal behavior and found that the reward component of the rational-choice model does not support the cost or deterrent component, as measured by perceived risks of formal sanction.
Abstract: This study examines the deterrent effect of formal sanctions on criminal behavior. While most research on deterrence assumes a rational-choice model of criminal decision-making, few studies consider all of the major elements of the model. In particular, three critical limitations characterize the empirical literature on deterrence: the failure to establish a causal ordering of sanctions and crime consistent with their temporal ordering; the focus on conventional populations and nonserious criminal acts, which are of less interest to the question of how society controls its members; and the inattention to the return or reward component of the decision-making process. To address these issues, we specify, estimate, and test a rational-choice model of crime on data that were collected on individuals, gathered within a longitudinal design, and derived from three distinct populations of persons at high risk of formal sanction. The results support the reward component of the rational-choice model, but fail to support the cost or deterrent component, as measured by perceived risks of formal sanctions. (abstract Adapted from Source: American Sociological Review, 1986. Copyright © 1986 by the American Sociological Association) Legal Sanctions Crime Prevention Deterrence Rational Choice Theory Adult Crime 07-02

Posted Content
TL;DR: This paper examined the deterrent effect of formal sanctions on criminal behavior and found that the reward component of the rational-choice model does not support the cost or deterrent component, as measured by perceived risks of formal sanction.
Abstract: This study examines the deterrent effect of formal sanctions on criminal behavior. While most research on deterrence assumes a rational-choice model of criminal decision-making, few studies consider all of the major elements of the model. In particular, three critical limitations characterize the empirical literature on deterrence: the failure to establish a causal ordering of sanctions and crime consistent with their temporal ordering; the focus on conventional populations and nonserious criminal acts, which are of less interest to the question of how society controls its members; and the inattention to the return or reward component of the decision-making process. To address these issues, we specify, estimate, and test a rational-choice model of crime on data that were collected on individuals, gathered within a longitudinal design, and derived from three distinct populations of persons at high risk of formal sanction. The results support the reward component of the rational-choice model, but fail to support the cost or deterrent component, as measured by perceived risks of formal sanctions. (abstract Adapted from Source: American Sociological Review, 1986. Copyright © 1986 by the American Sociological Association) Legal Sanctions Crime Prevention Deterrence Rational Choice Theory Adult Crime 07-02

Book ChapterDOI
TL;DR: Since both r and K can vary within a species and are subject to modification, the division of natural selection into r- and K-selection is of considerable basic interest in evolutionary ecology.
Abstract: The essence of the concept of r- and K-selection is that organisms strive to maximize their fitness for survival in either uncrowded (r-selection) or crowded (K-selection) environments. Fitness is defined following ecological convention as the proportion of genes left in the population gene pool (Pianka, 1983, p. 10). The terms r and K refer, respectively, to the maximum specific rate of increase (maximum specific growth rate minus minimum specific death rate) of an organism and to the density of individuals that a given environment can support at the population equilibrium. Since both r and K can vary within a species and are subject to modification, the division of natural selection into r- and K-selection is of considerable basic interest in evolutionary ecology.

Journal ArticleDOI
04 Jul 1986-Science
TL;DR: Voyager 2 images of the southern hemisphere of Uranus indicate that submicrometersize haze particles and particles of a methane condensation cloud produce faint patterns in the atmosphere, and Voyager images confirm the extremely low albedo of the ring particles.
Abstract: Voyager 2 images of the southern hemisphere of Uranus indicate that submicrometersize haze particles and particles of a methane condensation cloud produce faint patterns in the atmosphere. The alignment of the cloud bands is similar to that of bands on Jupiter and Saturn, but the zonal winds are nearly opposite. At mid-latitudes (-70 degrees to -27 degrees ), where winds were measured, the atmosphere rotates faster than the magnetic field; however, the rotation rate of the atmosphere decreases toward the equator, so that the two probably corotate at about -20 degrees . Voyager images confirm the extremely low albedo of the ring particles. High phase angle images reveal on the order of 10(2) new ringlike features of very low optical depth and relatively high dust abundance interspersed within the main rings, as well as a broad, diffuse, low optical depth ring just inside the main rings system. Nine of the newly discovered small satellites (40 to 165 kilometers in diameter) orbit between the rings and Miranda; the tenth is within the ring system. Two of these small objects may gravitationally confine the e ring. Oberon and Umbriel have heavily cratered surfaces resembling the ancient cratered highlands of Earth's moon, although Umbriel is almost completely covered with uniform dark material, which perhaps indicates some ongoing process. Titania and Ariel show crater populations different from those on Oberon and Umbriel; these were probably generated by collisions with debris confined to their orbits. Titania and Ariel also show many extensional fault systems; Ariel shows strong evidence for the presence of extrusive material. About halfof Miranda's surface is relatively bland, old, cratered terrain. The remainder comprises three large regions of younger terrain, each rectangular to ovoid in plan, that display complex sets of parallel and intersecting scarps and ridges as well as numerous outcrops of bright and dark materials, perhaps suggesting some exotic composition.

Book ChapterDOI
TL;DR: Despite their long history of use as food additives, much remains to be learned about sulfites, which would be helpful to the present concerns about their safety.
Abstract: Publisher Summary Sulfiting agents have a long history of use as food ingredients. Sulfur dioxide and several forms of inorganic sulfites, which liberate sulfur dioxide under the conditions of use, are food additives, collectively known as sulfiting agents. In addition to their use as food additives, the sulfites can also occur naturally in foods. Foods contain a variety of sulfur-containing compounds, including the sulfur amino acids, sulfates, sulfites, and sulfides. The key to the understanding of sulfite toxicity may lie in elucidation of sulfite metabolism. Several researchers have proposed that defects in sulfite metabolism among certain segments of the human population may put them at greater risk to the possible toxic effects of sulfite ingestion. If the current generally recognized as safe (GRAS) review leads to some limitation on the continued use of sulfites, it will be necessary to consider alternatives. Enzymatic browning will be inhibited by any process that destroys or inactivates the enzyme. Blanching would obviously work but is impractical for using on fresh fruits and vegetables. Despite their long history of use as food additives, much remains to be learned about sulfites, which would be helpful to the present concerns about their safety.