Showing papers by "University of Notre Dame published in 1996"
TL;DR: This biennial Review summarizes much of particle physics, using data from previous editions.
12,798 citations
TL;DR: In this paper, a clipped-optimal control strategy based on acceleration feedback for controlling magnetorheological dampers is proposed to reduce structural responses due to seismic loads, and a numerical example, employing a newly developed model that accurately portrays the salient characteristics of the MR dampers, is presented to illustrate the effectiveness of the approach.
Abstract: Control of civil engineering structures for earthquake hazard mitigation represents a relatively new area of research that is growing rapidly. Control systems for these structures have unique requirements and constraints. For example, during a severe seismic event, the external power to a structure may be severed, rendering control schemes relying on large external power supplies ineffective. Magnetorheological (MR) dampers are a new class of devices that mesh well with the requirements and constraints of seismic applications, including having very low power requirements. This paper proposes a clipped-optimal control strategy based on acceleration feedback for controlling MR dampers to reduce structural responses due to seismic loads. A numerical example, employing a newly developed model that accurately portrays the salient characteristics of the MR dampers, is presented to illustrate the effectiveness of the approach.
1,296 citations
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TL;DR: In this article, an analysis of the quantitative effects of agency costs in a real business cycle model is presented, showing that these costs can explain why output growth displays positive autocorrelation at short horizons.
Abstract: An analysis of the quantitative effects of agency costs in a real business cycle model, showing that these costs can explain why output growth displays positive autocorrelation at short horizons.
1,221 citations
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TL;DR: This paper used a new instrumental variable, the sex composition of the first two births in families with at least two children, to estimate the effect of additional children on parents' labor supply.
Abstract: Although theoretical models of labor supply and the family are well developed, there are few credible estimates of key empirical relationships in the work-family nexus. This study uses a new instrumental variable, the sex composition of the first two births in families with at least two children, to estimate the effect of additional children on parents' labor supply. Instrumental variables estimates using the sex mix are substantial but smaller than the corresponding ordinary least squares (OLS) estimates. Moreover, unlike the OLS estimates, the female labor supply effects estimated using sex-mix instruments appear to be absent among more educated women and women with high-wage husbands. We also find that married women who have a third child reduce their labor supply by as much as women in the full sample, while there is no relationship between wives' child-bearing and husbands' labor supply. Finally results to estimates produced using twins to generate instruments. Estimates using twins instruments are very close to the estimates generated by sex-mix instruments, once the estimators are corrected for differences in the ages of children whose birth was caused by the instruments. The estimates imply that the labor supply consequences of child-bearing disappear by the time the child is about 13 years old.
1,110 citations
TL;DR: A novel observation model based on motion compensated subsampling is proposed for a video sequence and Bayesian restoration with a discontinuity-preserving prior image model is used to extract a high-resolution video still given a short low-resolution sequence.
Abstract: The human visual system appears to be capable of temporally integrating information in a video sequence in such a way that the perceived spatial resolution of a sequence appears much higher than the spatial resolution of an individual frame. While the mechanisms in the human visual system that do this are unknown, the effect is not too surprising given that temporally adjacent frames in a video sequence contain slightly different, but unique, information. This paper addresses the use of both the spatial and temporal information present in a short image sequence to create a single high-resolution video frame. A novel observation model based on motion compensated subsampling is proposed for a video sequence. Since the reconstruction problem is ill-posed, Bayesian restoration with a discontinuity-preserving prior image model is used to extract a high-resolution video still given a short low-resolution sequence. Estimates computed from a low-resolution image sequence containing a subpixel camera pan show dramatic visual and quantitative improvements over bilinear, cubic B-spline, and Bayesian single frame interpolations. Visual and quantitative improvements are also shown for an image sequence containing objects moving with independent trajectories. Finally, the video frame extraction algorithm is used for the motion-compensated scan conversion of interlaced video data, with a visual comparison to the resolution enhancement obtained from progressively scanned frames.
1,058 citations
TL;DR: This paper studied the effect of protest form, context, and purpose on the likelihood of media coverage of public protests and found that the estimated size of a demonstration and its importance to the current media issue attention cycle are the strongest predictors of its coverage.
Abstract: Protest is now central to politics in Western democracies, but it is known to citizens mainly through portrayals in the media. Yet the media cover only a small fraction of public protests, raising the possibility of selection bias. We study this problem by comparing police records of demonstrations in Washington, D.C. in 1982 and 1991 with media coverage of the events in The New York Times, The Washington Post, and on three national television networks. We model the consequences of demonstration form, context, and purpose on the likelihood of media coverage. The estimated size of a demonstration and its importance to the current media issue attention cycle are the strongest predictors of its coverage. Additional analyses support our claim that heightened media attention to an issue increases the likelihood that protests related to that issue will be covered. Comparing 1982 to 1991 suggests that television coverage of protests is increasingly subject to the impact of media issue attention cycles.
572 citations
TL;DR: In this article, the degradation of a textile azo dye, acid orange 7, has been carried out on TiO2 particles using visible light using diffuse reflectance absorption and FTIR techniques.
Abstract: Photosensitized degradation of a textile azo dye, Acid Orange 7, has been carried out on TiO2 particles using visible light Mechanistic details of the dye degradation have been elucidated using diffuse reflectance absorption and FTIR techniques Degradation does not occur on Al2O3 surface or in the absence of oxygen The dependence of the dye degradation rate on the surface coverage shows the participation of excited dye and TiO2 semiconductor in the surface photochemical process Diffuse reflectance laser flash photolysis confirms the charge injection from the excited dye molecule into the conduction band of the semiconductor as the primary mechanism for producing oxidized dye radical The surface-adsorbed oxygen plays an important role in scavenging photogenerated electrons, thus preventing the recombination between the oxidized dye radical and the photoinjected electrons Diffuse reflectance FTIR was used to make a tentative identification of reaction intermediates and end products of dye degradation
504 citations
TL;DR: This work proposes a new approach to statistically optimal image reconstruction based on direct optimization of the MAP criterion, which requires approximately the same amount of computation per iteration as EM-based approaches, but the new method converges much more rapidly.
Abstract: Over the past years there has been considerable interest in statistically optimal reconstruction of cross-sectional images from tomographic data. In particular, a variety of such algorithms have been proposed for maximum a posteriori (MAP) reconstruction from emission tomographic data. While MAP estimation requires the solution of an optimization problem, most existing reconstruction algorithms take an indirect approach based on the expectation maximization (EM) algorithm. We propose a new approach to statistically optimal image reconstruction based on direct optimization of the MAP criterion. The key to this direct optimization approach is greedy pixel-wise computations known as iterative coordinate decent (ICD). We propose a novel method for computing the ICD updates, which we call ICD/Newton-Raphson. We show that ICD/Newton-Raphson requires approximately the same amount of computation per iteration as EM-based approaches, but the new method converges much more rapidly (in our experiments, typically five to ten iterations). Other advantages of the ICD/Newton-Raphson method are that it is easily applied to MAP estimation of transmission tomograms, and typical convex constraints, such as positivity, are easily incorporated.
493 citations
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TL;DR: In this paper, the authors examine the market reaction to an anticipated change in the demand for a stock using post-October 1989 data, and find significantly positive (negative) post-announcement abnormal returns that are only partially reversed following additions (deletions).
Abstract: Since October 1989, Standard and Poor s has (when possible) announced changes in the composition of the S&P 500 index one week in advance. Because index funds hold S&P 500 stocks to minimize tracking error, index composition changes since this date provide an opportunity to examine the market reaction to an anticipated change in the demand for a stock. Using post-October-1989 data, we document significantly positive (negative) post-announcement abnormal returns that are only partially reversed following additions (deletions). These results indicate the existence of temporary price pressure and downward-sloping log-run demand curves for stocks and represent a violation of market efficiency.
476 citations
TL;DR: It would appear that lysine binding capability does not correlate with the relative inhibitory effects of the kringle-containing constructs, as it is demonstrated that appropriate folding of kringles structures is essential for angiostatin to maintain its full anti-endothelial activity.
414 citations
TL;DR: In this paper, the authors developed a model to explain the variance in price search in markets in which search is a regularly occurring activity and developed a method to identify the factors that might explain this variance.
Abstract: The literature has produced an incomplete understanding of factors explaining the variance in price search in markets in which search is a regularly occurring activity. The authors develop a model ...
TL;DR: In this paper, photoelectrochemical and photocatalytic degradation experiments carried out in both nitrogen- and oxygen-saturated solutions with an externally applied electrochemical bias provide useful information in optimizing semiconductor concentrations in a composite film.
Abstract: Nanostructured semiconductor films of SnO2, TiO2 and SnO2/TiO2 have been employed for electrochemically assisted photocatalytic degradation of a textile azo dye naphthol blue black (NBB). The degradation rate is significantly higher for SnO2/TiO2 composite films than SnO2 and TiO2 films alone. An effort has been made to correlate the photoelectrochemical behavior of these films to the rate of photocatalytic degradation of NBB. The enhanced degradation rate of NBB using composite semiconductor films is attributed to increased charge separation in these systems. Photoelectrochemical and photocatalytic degradation experiments carried out in both nitrogen- and oxygen-saturated solutions with an externally applied electrochemical bias provide useful information in optimizing semiconductor concentrations in a composite film.
TL;DR: In this paper, the authors examine the dynamic behavior of quantum cellular automata, arrays of artificial quantum-dot cells that can be used to perform useful computations, and they develop several approximate techniques for reducing the size of the basis set required.
Abstract: We examine the dynamic behavior of quantum cellular automata, arrays of artificial quantum‐dot cells that can be used to perform useful computations. The dynamics of the array can be solved directly, retaining the full many‐electron degrees of freedom only for small array sizes. For larger arrays, we develop several approximate techniques for reducing the size of the basis set required. We examine the effect of intercellular quantum correlations on the switching response. Several important examples of switching behavior are solved using the techniques developed.
TL;DR: The analysis of excision events for two representatives of this family of short‐inverted‐repeat elements, tagalong and piggysac, provides further validation for their inclusion in a single family of unique transposons.
Abstract: Transposon mutagenesis of baculoviruses provides an ideal experimental system for analysis of the movement of a unique family of mobile element identified from lepidopteran genomes. Members of this family of short-inverted-repeat elements are characterized by their extreme specificity for TTAA target sites. This report describes the analysis of excision events for two representatives of this family, tagalong (formerly TFP3) and piggyBac (formerly IFP2). These elements were tagged with a polyhedrin/lacZ reporter gene and inserted back into the virus genome either by homologous recombination or by transposition. Revertants were selected based on a white plaque phenotype. Both elements excise in a precise fashion from their positions in the baculovirus genome in either TN-368 cells or IPLB-SF21 AE cells. The precise excision of these elements in infected IPLB-SF21 AE cells occurs in the absence of either tagalong or piggyBac element encoded functions. The common characteristics of both insertion and excision for these elements provides further validation for their inclusion in a single family of unique transposons.
TL;DR: In this article, the authors review the important advances in the field of flow control that took place during the past few years, and present less complex control schemes, passive as well as active, are more market ready and are also witnessing resurgence of interest.
Abstract: This brief article reviews the important advances in the field of flow control that took place during the past few years. This broad area of research remains of great interest for its numerous potential benefits for both the military and civilian sectors. Spurred by the recent developments in chaos control, microfabrication and neural networks, reactive control of turbulent flows is now in the realm of the possible for future practical devices. Other less complex control schemes, passive as well as active, are more market ready and are also witnessing resurgence of interest. 115 refs., 4 figs.
TL;DR: Despite the absence of IL-4, the genetically pure BALB/c mutant mice remained susceptible to L. major infection, showed no signs of lesion healing or parasite clearance, and did not switch to a TH1 phenotype.
Abstract: Interleukin-4 (IL-4), a pleiotropic cytokine, is a major regulator of the immune system and is considered crucial for the development of T helper cell type 2 (TH2) responses. The susceptibility of BALB/c mice to infection with Leishmania major has been associated with a polarized TH2 response and an inability to down-modulate IL-4 production. The role of IL-4 in vivo was examined directly by disrupting the IL-4 gene in BALB/c embryonic stem cells. Despite the absence of IL-4, the genetically pure BALB/c mutant mice remained susceptible to L. major infection, showed no signs of lesion healing or parasite clearance, and did not switch to a TH1 phenotype.
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TL;DR: Estimates suggest that workplace bans reduce smoking prevalence by 5 percentage points and average daily consumption among smokers by 10 percent, which can explain all of the recent sharp fall in smoking among workers relative to non-workers.
Abstract: In recent years there has been a heightened public concern over the potentially harmful effects of environmental tobacco smoke (ETS). In response, smoking has been banned on many jobs. Using data from the 1991 and 1993 National Health Interview Survey and smoking supplements to the September 1992 and May 1993 Current Population Survey, we investigate whether these workplace policies reduce smoking prevalence and smoking intensity among workers. Our estimates suggest that workplace bans reduce smoking prevalence by 5 percentage points and average daily consumption among smokers by 10 percent. The impact of the ban is greatest for those with longer work weeks. Although workers with better health habits are more likely to work at establishments with workplace smoking bans, estimates from bivariate probit and two-stage least square equations suggest that these estimates are not subject to an omitted variables bias. The rapid increase in workplace bans can explain all of the recent sharp fall in smoking among workers relative to non-workers.
TL;DR: It is shown that separability is an intrinsic property of the measured signals and can be described by the concept of m-row decomposability introduced in this paper, and that separation principles can be developed by using the structure characterization theory of random variables.
Abstract: This paper identifies and studies two major issues in the blind source separation problem: separability and separation principles. We show that separability is an intrinsic property of the measured signals and can be described by the concept of m-row decomposability introduced in this paper; we also show that separation principles can be developed by using the structure characterization theory of random variables. In particular, we show that these principles can be derived concisely and intuitively by applying the Darmois-Skitovich theorem, which is well known in statistical inference theory and psychology. Some new insights are gained for designing blind source separation filters.
TL;DR: In this paper, the authors examine historical classification schemes of peatlands and, in this context, gradients of alkalinity, pH, nutrient availability for plant growth, nutrient mineralization, hydrology, and decomposition.
Abstract: Peatlands often have readily apparent gradients of plant species distributions, biogeochemistry, and hydrology across several spatial scales. Many inferences have been drawn about the colinearity of these gradients, and these assumptions have become ingrained in the terminology that describes and classifies peatlands. We review the literature and present some of our own data that show that many of these inferences are either wrong or correct only under a limited set of ecological conditions. We examine historical classification schemes of peatlands and, in this context, gradients of alkalinity, pH, nutrient availability for plant growth, nutrient mineralization, hydrology, and decomposition. We further suggest a strictly defined set of terms to describe separate gradients of hydrology, alkalinity, and nutrients that limit plant growth in peatlands. Specifically, we make the following suggestions concerning terminology. (1) The suffix “-trophic” should only be used when referring to nutrients that directly limit plant growth at natural availabilities (e.g., eutrophic and oligotrophic). (2) Terms such as circumneutral, moderately acid, and very acidic (or alternatively strong, intermediate, and weak) should be used to describe the pH of peatlands. (3) Ombrogenous and geogenous (or limnogenous, topogenous, and soligenous) should be used to describe the hydrology of peatlands. (4) The terms bog and fen should be defined broadly based on water/soil chemistry and dominant plant species without accompanying assumptions regarding hydrology, topography, ontogeny, nutrient availability, or the presence or absence of nondominant indicator plant species. Better yet, the generic term peatland be used when possible to avoid confusion about conditions that may or may not be present at a particular site.
TL;DR: Cooperating security managers (CSM) is designed to perform intrusion detection and reporting functions in a distributed environment without requiring a designated central site or server to perform the analysis of network audit data.
Abstract: The need for increased security measures in computer systems and networks is apparent through the frequent media accounts of computer system and network intrusions. One attempt at increasing security measures is in the area of intrusion detection packages. These packages use a variety of means to detect intrusive activities and have been applied to both individual computer systems and networks. Cooperating security managers (CSM) is one such package. Applied to a network, CSM is designed to perform intrusion detection and reporting functions in a distributed environment without requiring a designated central site or server to perform the analysis of network audit data. In addition, it is designed to handle intrusions as opposed to simply detecting and reporting on them, resulting in a comprehensive approach to individual system and network intrusions. Tests of the initial prototype have shown the cooperative methodology to perform favourably.
TL;DR: The authors obtained self-reports, peer nominations, teacher ratings, and parent reports of depression and social and academic competence on 490 3rd graders and 455 6th graders near the beginning and end of the school year.
Abstract: The authors obtained self-reports, peer nominations, teacher ratings, and parent reports of depression and social and academic competence on 490 3rd graders and 455 6th graders near the beginning and end of the school year. Confirmatory factor analysis and structural equation modeling revealed that (a) measures showed significant convergent and discriminant validity; (b) within-wave correlations between constructs were large and significant, although the depression-social competence correlation was larger than the depression-academic competence correlation; (c) the cross-wave stability of all constructs was remarkably high; and (d) social competence at Wave 1 predicted depression at Wave 2 for 6th graders after controlling for depression at Wave 1. Depression did not predict change in either academic or social competence over time. Implications for competencebased and failure-based models of child depression are discussed.
TL;DR: In this article, the results of experiments of direct and sensitized photocatalysis of 4-nitrophenol using an annular reactor, TiO2, and an artificial light source were reported.
TL;DR: In this article, the effects of damping on the system response are analyzed in terms of a perturbation technique, second-moment analysis and Monte Carlo simulation. And the implications of the uncertainty of dampness on system response have been discussed.
TL;DR: In this article, a clipped-optimal control strategy for controlling magnetorheological dampers to reduce structural responses due to seismic loads is presented, employing a newly developed model that accurately portrays the salient characteristics of the MR dampers.
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TL;DR: In this article, the authors investigate the association between disagreement coincident with earnings announcements and investors' trading decisions and find that three distinctly different aspects of disagreement each play an incremental role in explaining trading volume around earnings announcements.
Abstract: This paper investigates the association between disagreement coincident with earnings announcements and investors' trading decisions. Theory suggests that trading volume arises because of investor disagreement, but disagreement is a multi-faceted construct. We find that three distinctlydifferent aspects of disagreement each play an incremental role in explaining trading volume around earnings announcements, even after controlling for the magnitude of the contemporaneous price change. These aspects of disagreement are: dispersion in prior beliefs, divergence in beliefs, and belief jumbling. Dispersion in prior beliefs is the cross-sectional variation in expectations before the earnings announcement, divergence in beliefs is the change in the dispersion in beliefs, and belief jumbling occurs when investors' beliefs change positions relative to each other. Our results indicate that each of these three aspects of disagreement coincident with earnings announcements affects investors' real economic (i.e., trading) decisions.
01 Jan 1996
TL;DR: The evidence that general relativistic effects may cause the stars to individually collapse into black holes prior to merging and the strong fields cause the last stable orbit to occur at a larger separation distance and lower frequency than previously estimated is discussed.
Abstract: We describe a numerical method for calculating the (3+1)-dimensional general relativistic hydrodynamics of a coalescing neutron-star binary system. The relativistic field equations are solved at each time slice with a spatial three-metric chosen to be conformally flat. Against this solution to the general relativistic field equations, the hydrodynamic variables and gravitational radiation are allowed to respond. The gravitational radiation signal is derived via a multipole expansion of the metric perturbation to the hexadecapole ({ital l}=4) order including both mass and current moments and a correction for the slow-motion approximation. Using this expansion, the effect of gravitational radiation on the system evolution can also be recovered by introducing an acceleration term in the matter evolution. In the present work we illustrate the method by applying this model to evaluate various orbits of two neutron stars with a gravitational mass of 1.45{ital M}{sub {circle_dot}} near the time of the final merger. We discuss the evidence that, for a realistic neutron-star equation of state, general relativistic effects may cause the stars to individually collapse into black holes prior to merging. Also, the strong fields cause the last stable orbit to occur at a larger separation distance and lower frequency than previously estimated. {copyright}more » {ital 1996 The American Physical Society.}« less
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TL;DR: This paper analyzed the economic determinants of developing country creditworthiness indicators for over 60 developing countries for the period from 1980 to 1993, and found that economic fundamentals such as non-gold foreign exchange reserves to imports, the ratio of the current account balance to GDP, growth, and inflation explain a large amount of the variation in the credit ratings.
Abstract: This paper analyzes the economic determinants of developing country creditworthiness indicators for over 60 developing countries for the period from 1980 to 1993. Our results indicate that economic fundamentals--the ratio of non-gold foreign exchange reserves to imports, the ratio of the current account balance to GDP, growth, and inflation explain a large amount of the variation in the credit ratings. All developing country ratings were adversely affected by an increase in international interest rates independently of the domestic economic fundamentals. A country`s regional location and the structure of its exports (such as whether it is primarily an exporter of fuel products or manufactured products) were also important.
TL;DR: In this paper, a coherent structure for enhancing the ethical competence of psychologists and counselors and the level of public trust in the character and actions of these professions and their members is proposed.
Abstract: Principle ethics can be described as a set of prima facie obligations one considers when confronted with an ethical dilemma. Virtue ethics focuses on character traits and nonobligatory ideals that facilitate the development of ethical individuals. Within the context of the assumption that the major responsibilities or primary goals of professionals are to be competent and to serve the common good, we suggest that integrating these complementary ethical perspectives provides a coherent structure for enhancing the ethical competence of psychologists and counselors and the level of public trust in the character and actions of these professions and their members. Virtue ethics, rooted in the narratives and aspirations of specific communities, can be particularly helpful to professionals in discerning appropriate ethical conduct in multicultural settings and interactions. We propose that future directions for research and instruction be expanded from quandary ethics to encompass issues of character