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Showing papers by "Rutgers University published in 1993"


Proceedings ArticleDOI
01 Jun 1993
TL;DR: An efficient algorithm is presented that generates all significant association rules between items in the database of customer transactions and incorporates buffer management and novel estimation and pruning techniques.
Abstract: We are given a large database of customer transactions. Each transaction consists of items purchased by a customer in a visit. We present an efficient algorithm that generates all significant association rules between items in the database. The algorithm incorporates buffer management and novel estimation and pruning techniques. We also present results of applying this algorithm to sales data obtained from a large retailing company, which shows the effectiveness of the algorithm.

15,645 citations


Journal ArticleDOI
TL;DR: It is shown that physically $\ensuremath{\Delta}P can be interpreted as a displacement of the center of charge of the Wannier functions.
Abstract: We consider the change in polarization \ensuremath{\Delta}P which occurs upon making an adiabatic change in the Kohn-Sham Hamiltonian of the solid. A simple expression for \ensuremath{\Delta}P is derived in terms of the valence-band wave functions of the initial and final Hamiltonians. We show that physically \ensuremath{\Delta}P can be interpreted as a displacement of the center of charge of the Wannier functions. The formulation is successfully applied to compute the piezoelectric tensor of GaAs in a first-principles pseudopotential calculation.

3,136 citations


Journal ArticleDOI
TL;DR: The ability of the Markov model to represent repetitive events and the time dependence of both probabilities and utilities allows for more accurate representation of clinical settings that involve these issues.
Abstract: Markov models are useful when a decision problem involves risk that is continuous over time, when the timing of events is important, and when important events may happen more than once. Representing such clinical settings with conventional decision trees is difficult and may require unrealistic simplifying assumptions. Markov models assume that a patient is always in one of a finite number of discrete health states, called Markov states. All events are represented as transitions from one state to another. A Markov model may be evaluated by matrix algebra, as a cohort simulation, or as a Monte Carlo simulation. A newer representation of Markov models, the Markov-cycle tree, uses a tree representation of clinical events and may be evaluated either as a cohort simulation or as a Monte Carlo simulation. The ability of the Markov model to represent repetitive events and the time dependence of both probabilities and utilities allows for more accurate representation of clinical settings that involve these issues.

2,360 citations


Journal ArticleDOI
Theda Skocpol1
TL;DR: Theda Skocpol et al. as discussed by the authors show that the United States nearly became a unique maternalist welfare state as the federal government and more than 40 states enacted social spending, labour regulations, and health education programmes to assist American mothers and children.
Abstract: It is generally believed that the United States lagged behind the countries of Western Europe in developing modern social policies. But, as Theda Skocpol shows in this historical analysis, the United States actually pioneered generous social spending for many of its elderly, disabled and dependent citizens. During the late 19th century, competitive party politics in American democracy led to the rapid expansion of benefits for Union Civil War veterans and their families. Some Americans hoped to expand veterans' benefits into pensions for all of the needy elderly and social insurance for workingmen and their families. But such hopes went against the logic of political reform in the Progressive era. Generous social spending faded along with the Civil War generation. Instead, the U.S. nearly became a unique maternalist welfare state as the federal government and more than 40 states enacted social spending, labour regulations, and health education programmes to assist American mothers and children. As Skocpol shows, many of these policies were enacted even before American women were granted the right to vote. Banned from electoral politics, they turned their energies to creating huge, nation-spanning federations of women's clubs, which collaborated with reform-minded professional women to spur legislative action across the country. Blending original historical research with political analysis, Skocpol shows how governmental institutions, electoral rules, political parties and earlier public policies combined to determine both the opportunities and the limits within which social policies were devised and changed by reformers and politically active social groups over the course of the late 19th and early 20th centuries.

2,288 citations


Journal ArticleDOI
02 Jul 1993-Science
TL;DR: The three-dimensional structure of the head portion of myosin, or subfragment-1, which contains both the actin and nucleotide binding sites, is described, and this structure of a molecular motor was determined by single crystal x-ray diffraction.
Abstract: Directed movement is a characteristic of many living organisms and occurs as a result of the transformation of chemical energy into mechanical energy. Myosin is one of three families of molecular motors that are responsible for cellular motility. The three-dimensional structure of the head portion of myosin, or subfragment-1, which contains both the actin and nucleotide binding sites, is described. This structure of a molecular motor was determined by single crystal x-ray diffraction. The data provide a structural framework for understanding the molecular basis of motility.

1,927 citations


Journal ArticleDOI
TL;DR: Findings indicate that vitamin and mineral supplementation of the diet of Linxian adults, particularly with the combination of beta carotene, vitamin E, and selenium, may effect a reduction in cancer risk in this population.
Abstract: Background Epidemiologic evidence indicates that diets high in fruits and vegetables are associated with a reduced risk of several cancers, including cancers of the esophagus and stomach. Vitamins and minerals in these foods may contribute to the reduced cancer risk. The people of Linxian County, China, have one of the world's highest rates of esophageal/gastric cardia cancer and a persistently low intake of several micronutrients. Purpose We sought to determine if dietary supplementation with specific vitamins and minerals can lower mortality from or incidence of cancer as well as mortality from other diseases in Linxian. Methods Individuals of ages 40-69 were recruited in 1985 from four Linxian communes. Mortality and cancer incidence during March 1986-May 1991 were ascertained for 29,584 adults who received daily vitamin and mineral supplementation throughout this period. The subjects were randomly assigned to intervention groups according to a one-half replicate of a 2(4) factorial experimental design. This design enabled testing for the effects of four combinations of nutrients: (A) retinol and zinc; (B) riboflavin and niacin; (C) vitamin C and molybdenum; and (D) beta carotene, vitamin E, and selenium. Doses ranged from one to two times U.S. Recommended Daily Allowances. Results A total of 2127 deaths occurred among trial participants during the intervention period. Cancer was the leading cause of death, with 32% of all deaths due to esophageal or stomach cancer, followed by cerebrovascular disease (25%). Significantly (P = .03) lower total mortality (relative risk [RR] = 0.91; 95% confidence interval [CI] = 0.84-0.99) occurred among those receiving supplementation with beta carotene, vitamin E, and selenium. The reduction was mainly due to lower cancer rates (RR = 0.87; 95% CI = 0.75-1.00), especially stomach cancer (RR = 0.79; 95% CI = 0.64-0.99), with the reduced risk beginning to arise about 1-2 years after the start of supplementation with these vitamins and minerals. No significant effects on mortality rates from all causes were found for supplementation with retinol and zinc, riboflavin and niacin, or vitamin C and molybdenum. Patterns of cancer incidence, on the basis of 1298 cases, generally resembled those for cancer mortality. Conclusions The findings indicate that vitamin and mineral supplementation of the diet of Linxian adults, particularly with the combination of beta carotene, vitamin E, and selenium, may effect a reduction in cancer risk in this population. Implications The results on their own are not definitive, but the promising findings should stimulate further research to clarify the potential benefits of micronutrient supplements.

1,706 citations


Journal ArticleDOI
17 Dec 1993-Science
TL;DR: Salicylic acid specifically inhibited the catalase activity in vitro and induced an increase in H2O2 concentrations in vivo, suggesting involvement in SA-mediated induction of systemic acquired resistance (SAR) in plants.
Abstract: A complementary DNA encoding a salicylic acid (SA)-binding protein has been cloned. Its properties suggest involvement in SA-mediated induction of systemic acquired resistance (SAR) in plants. The sequence of the protein is similar to that of catalases and the protein exhibits catalase activity. Salicylic acid specifically inhibited the catalase activity in vitro and induced an increase in H2O2 concentrations in vivo. H2O2 or compounds, such as SA, that inhibit catalases or enhance the generation of H2O2, induced expression of defense-related genes associated with SAR. Thus, the action of SA in SAR is likely mediated by elevated amounts of H2O2.

1,177 citations


Journal ArticleDOI
TL;DR: It is shown how the ultrasoft pseudopotentials which have recently been proposed by Vanderbilt can be implemented efficiently in the context of Car-Parrinello molecular-dynamics simulations.
Abstract: We show how the ultrasoft pseudopotentials which have recently been proposed by Vanderbilt can be implemented efficiently in the context of Car-Parrinello molecular-dynamics simulations We address the differences with respect to the conventional norm-conserving schemes, identify certain problems which arise, and indicate how these problems can be overcome This scheme extends the possibility of performing first-principles molecular dynamics to systems including first-row elements and transition metals

1,106 citations


Journal ArticleDOI
TL;DR: The structure of the HIV-1 RT/DNA/Fab complex should aid the understanding of general mechanisms of nucleic acid polymerization and AIDS therapies may be enhanced by a fuller understanding of drug inhibition and resistance emerging from these studies.
Abstract: The crystal structure of a ternary complex of human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) heterodimer (p66/p51), a 19-base/18-base double-stranded DNA template-primer, and a monoclonal antibody Fab fragment has been determined at 3.0 A resolution. The four individual subdomains of RT that make up the polymerase domains of p66 and p51 are named fingers, palm, thumb, and connection [Kohlstaedt, L. A., Wang, J., Friedman, J. M., Rice, P. A. & Steitz, T. A. (1992) Science 256, 1783-1790]. The overall folding of the subdomains is similar in p66 and p51 but the spatial arrangements of the subdomains are dramatically different. The template-primer has A-form and B-form regions separated by a significant bend (40-45 degrees). The most numerous nucleic acid interactions with protein occur primarily along the sugar-phosphate backbone of the DNA and involve amino acid residues of the palm, thumb, and fingers of p66. Highly conserved regions are located in the p66 palm near the polymerase active site. These structural elements, together with two alpha-helices of the thumb of p66, act as a clamp to position the template-primer relative to the polymerase active site. The 3'-hydroxyl of the primer terminus is close to the catalytically essential Asp-110, Asp-185, and Asp-186 residues at the active site and is in a position for nucleophilic attack on the alpha-phosphate of an incoming nucleoside triphosphate. The structure of the HIV-1 RT/DNA/Fab complex should aid our understanding of general mechanisms of nucleic acid polymerization. AIDS therapies may be enhanced by a fuller understanding of drug inhibition and resistance emerging from these studies.

1,099 citations


Journal ArticleDOI
TL;DR: In this review most of the various known, suspected, or postulated functions of osteopontin, a secreted highly acidic phosphoprotein, are discussed in terms of what the authors currently know about the protein.
Abstract: In this review most of the various known, suspected, or postulated functions of osteopontin, a secreted highly acidic phosphoprotein, are discussed in terms of what we currently know about the protein. These include 1) binding of OPN both to cells via a GRGDS cell adhesion sequence that recognizes the alpha v beta 3 integrin and to extracellular matrix components via poorly characterized motifs, 2) regulation of the formation and remodeling of mineralized tissue, 3) recruiting and stimulating macrophages and lymphocytes as part of a nonspecific response to microbial infections, 4) multiple interactions with Ca2+ that likely influence OPN protein conformation and may be important in Ca(2+)-mediated or Ca(2+)-dependent processes, 5) inhibiting the growth of calcium oxalate crystals by disruption of the growing crystal lattice, 6) effects on gene expression, Ca2+ regulation, and nitric oxide production, and 7) involvement in cell migration. OPN production is frequently augmented when cell signaling pathways are activated by any of a variety of stimuli, for example in cancer cells.

1,094 citations


Journal ArticleDOI
TL;DR: A critical review of the relationship between tea consumption and human cancer risk is provided, covering basic chemistry and biochemical activity of tea, epidemiologic investigations, and laboratory studies, as well as possible directions for future research.
Abstract: Tea is one of the most popular beverages consumed worldwide. The relationship between tea consumption and human cancer incidence is an important concern. This topic has been studied in different populations by many investigators, but no clear-cut conclusion can be drawn. Whereas some studies have shown a protective effect of tea consumption against certain types of cancers, other studies have indicated an opposite effect. Our purpose is to provide a critical review of this topic, covering basic chemistry and biochemical activity of tea, epidemiologic investigations, and laboratory studies, as well as possible directions for future research. Studies have demonstrated either a lack of association between tea consumption and cancer incidence at specific organ sites or inconsistent results. On the other hand, many laboratory studies have demonstrated inhibitory effects of tea preparations and tea polyphenols against tumor formation and growth. This inhibitory activity is believed to be mainly due to the antioxidative and possible antiproliferative effects of polyphenolic compounds in green and black tea. These polyphenolics may also inhibit carcinogenesis by blocking the endogenous formation of N-nitroso compounds, suppressing the activation of carcinogens, and trapping of genotoxic agents. The effect of tea consumption on cancer is likely to depend on the causative factors of the specific cancer. Therefore, a protective effect observed on a certain cancer with a specific population may not be observable with a cancer of a different etiology. On the basis of this concept, we suggest future laboratory and epidemiologic studies to elucidate the relationship between tea consumption and human cancer risk.

Journal ArticleDOI
TL;DR: This article examined the relationship between two carefully specified dimensions of teacher efficacy (general and personal teaching efficacy) and aspects of a healthy school climate (institutional integrity, principal influence, consideration, resource support, morale, and academic emphasis).
Abstract: This study examined the relationships between 2 carefully specified dimensions of teacher efficacy (general and personal teaching efficacy) and aspects of a healthy school climate (institutional integrity, principal influence, consideration, resource support, morale, and academic emphasis). The sample was composed of 179 teachers, randomly selected from 37 elementary schools in New Jersey. A teacher efficacy scale and a version of the Organizational Health Inventory were administered to the teachers in their schools by a researcher. Correlation and regression analyses were used to examine relationships among variables. Our primary concern was with individual teacher efficacy; hence, individual teacher perception served as the unit of analysis. We found that a healthy school climate-one with a strong academic emphasis and a principal who has influence with superiors and is willing to use it on behalf of teachers-was conducive to the development of teachers' beliefs that they can influence student learning ...

Journal ArticleDOI
TL;DR: In this article, four competing theories of health-protective behavior are reviewed: the health belief model, the theory of reasoned action, protection motivation theory, and subjective expected utility theory.
Abstract: Four competing theories of health-protective behavior are reviewed: the health belief model, the theory of reasoned action, protection motivation theory, and subjective expected utility theory. In spite of their commonalities, these models are seldom tested against one another. The review points out the similarities and differences among these theories and the data and analyses needed to compare them. In addition to describing the content of the models, their conceptualization of key variables, and the combinatorial rules used to make predictions, some general problems in theory development and testing for health behaviors are examined. The article's goal is to help investigators design studies that will clarify the strengths and weaknesses of these models, leading toward a better understanding of health behavior.

Journal ArticleDOI
TL;DR: It is shown that the polarization as defined above also has a direct and predictive relationship to the surface charge which accumulates at an insulating surface or interface.
Abstract: A definition of the electric polarization of an insulating crystalline solid is given in terms of the centers of charge of the Wannier functions of the occupied bands The change of this quantity under an adiabatic evolution of the Hamiltonian has previously been shown to correspond to the physical change in polarization Here, we show that the polarization as defined above also has a direct and predictive relationship to the surface charge which accumulates at an insulating surface or interface

Journal ArticleDOI
TL;DR: In this paper, the authors present evidence supporting the hypothesis that a basic temporal processing impairment in language-impaired children underlies their inability to integrate sensory information that converges in rapid succession in the central nervous system.
Abstract: In this paper we present evidence supporting the hypothesis that a basic temporal processing impairment in language-impaired children underlies their inability to integrate sensory information that converges in rapid succession in the central nervous system. We provide data showing that this deficit is pansensory; that is, affects processing in multiple sensory modalities, and also affects motor output within the millisecond time frame. We also provide data that links these basic temporal integration deficits to specific patterns of speech perception and speech production deficits in language-impaired children. We suggest that these basic temporal deficits cause a cascade of effects starting with disruption of the normal development of an otherwise effective and efficient phonological system. We propose further that these phonological processing deficits result in subsequent failure to learn to speak and to read normally. That is, both the language and reading problems have their basis in deficiently esta...

Book ChapterDOI
TL;DR: In this paper, the authors study the effectiveness of honor codes in a more complex social context and compare academic dishonesty in colleges that have honor codes and those that do not, and find that the existence of an honor code may not be the only predictor of cheating behavior.
Abstract: Research and media reports have established the continued pervasiveness of academic dishonesty among students on America's college campuses [12, 13, 22, 25, 26, 33, 46]. While some colleges have responded with academic integrity classes and increased efforts to convince reluctant faculty members to report student cheaters [13], there is a renewed interest in the concept of "community" as an effective foundation for campus governance. For example, the Carnegie Foundation for the Advancement of Teaching's special report, Campus Life: In Search of Community, concludes, "What is needed, we believe, is a larger, more integrative vision of community in higher education. . . . a place where individuals accept their obligations to the group and where well-defined governance procedures guide behavior for the common good" [10, p. 7]. Derek Bok, in Universities and the Future of American, echoes this theme: [U]niversities need to consider the larger campus environment beyond the classroom. An obvious step in this direction is to have rules tha t prohibit lying, cheating, stealing, violent behavior, interference with free expression, or other acts that break fundamental norms. Such rules not only protect the rights of everyone in the community; they also signal the importance of basic moral obligations and strengthen habits of ethical behavior [5, pp. 84-85]. Bok offers the honor code as perhaps the most effective approach in matters of academic integrity, but acknowledges that, "the pervasive competition for grades; the size, diversity, and impersonal nature of many large universities; their lack of any honor code traditon; and the wide-spread distaste for accusing one's classmates" combine to work against such an approach [5, p. 87]. Although the honor code traditon dates back over a century, the viability of such codes on today's campuses is open to some question [12]. Small, relatively homogeneous campuses have generally given way to large, culturally diverse institutions which lack any apparent sense of community or common purpose among students other than getting a credential and a job. Despite the fundamental nature of this question, there is a surprising paucity of empirical research which addresses the effectiveness of honor codes. the study discussed here attempts to help fill this gap by comparing academic dishonesty in colleges that have honor codes and those that do not. The few studies that have addressed the effectiveness of honor codes [7, 9] have generally considered code effectiveness independent of context. We believe that it is important to acknowledge and understand the complexity of the social systems within which honor codes are embedded and the fact that other contextual factors may be as important or more important than the existence of an honor code by itself. Thus this study extends beyond previous work by studying the effectiveness of honor codes within a more complex social context. Honor Codes in Context Academic Dishonesty Depending on one's definition of academic dishonesty, the data collection methods employed, and other variables, prior studies report that anywhere from 13 to 95 percent of college students engage in some form of academic dishonesty [12, 17, 20, 21, 26, 30, 31, 42]. A major dichotomy that separates these prior studies is the level of analysis. One stream of research has focused on individual differences though to be predictive of cheating behavior, such as gender [45], grade point average [1, 22,], work ethic [15], Type A behavior, competitive achievement-striving [35], and self-esteem [44]. In contrast, other studies have concentrated on the institutional level of analysis and examined such contextual factors as honor codes [7, 8, 9], faculty responses to cheating [26], sanction threats [33, 42], and social learning [33]. Although the "individual differences" approach helps to understand individuals' predispositions to cheat, the findings are not particularly useful to the university administrator searching for effective institutional responses to issues of academic dishonesty. …

Journal ArticleDOI
TL;DR: This article examined three broad arguments for generalizing from data: sample-to-population extrapolation, analytic generalization, and case-to case transfer, and concluded that analytic generalisation can be very helpful for qualitative researchers but that sample to population extrapolation is not likely to be.
Abstract: One criticism about qualitative research is that it is difficult to generalize findings to settings not studied. To explore this issue, I examine three broad arguments for generalizing from data: sample-to-population extrapolation, analytic generalization, and case-to-case transfer. Qualitative research often uses the last argument, but some efforts have been made to use the first two. I suggest that analytic generalization can be very helpful for qualitative researchers but that sample-to-population extrapolation is not likely to be.

Journal ArticleDOI
TL;DR: The ability to transform routinely plastids of land plants opens the way to manipulate the process of photosynthesis and to incorporate novel genes into the plastid genome of crops.
Abstract: We report here a 100-fold increased frequency of plastid transformation in tobacco by selection for a chimeric aadA gene encoding aminoglycoside 3"-adenylyltransferase, as compared with that obtained with mutant 16S rRNA genes. Expression of aadA confers resistance to spectinomycin and streptomycin. In transforming plasmid pZS197, a chimeric aadA is cloned between rbcL and open reading frame ORF512 plastid gene sequences. Selection was for spectinomycin resistance after biolistic delivery of pZS197 DNA into leaf cells. DNA gel-blot analysis confirmed incorporation of the chimeric aadA gene into the plastid genome by two homologous recombination events via the flanking plastid gene sequences. The chimeric gene became homoplasmic in the recipient cells and is uniformly transmitted to the maternal seed progeny. The ability to transform routinely plastids of land plants opens the way to manipulate the process of photosynthesis and to incorporate novel genes into the plastid genome of crops.

Journal ArticleDOI
TL;DR: The experimental results provide evidence that bandpass-filtered speech signals around speech formants contain amplitude and frequency modulations within a pitch period, and several efficient algorithms are developed and compared for estimating the amplitude envelope and instantaneous frequency of discrete-time AM-FM signals.
Abstract: An efficient solution to the fundamental problem of estimating the time-varying amplitude envelope and instantaneous frequency of a real-valued signal that has both an AM and FM structure is provided. Nonlinear combinations of instantaneous signal outputs from the energy operator are used to separate its output energy product into its AM and FM components. The theoretical analysis is done first for continuous-time signals. Then several efficient algorithms are developed and compared for estimating the amplitude envelope and instantaneous frequency of discrete-time AM-FM signals. These energy separation algorithms are used to search for modulations in speech resonances, which are modeled using AM-FM signals to account for time-varying amplitude envelopes and instantaneous frequencies. The experimental results provide evidence that bandpass-filtered speech signals around speech formants contain amplitude and frequency modulations within a pitch period. >

Journal ArticleDOI
TL;DR: These patterns of genetic variation were very different from those reported for inbred species and provide important baseline data for cultivar identification and continuing studies of the evolution of polyploid races in this species.
Abstract: RAPD markers provide a powerful tool for the investigation of genetic variation in natural and domesticated populations. Recent studies of strain/cultivar identification have shown extensive RAPD divergence among, but little variation within, inbred species or cultivars. In contrast, little is known about the pattern and extent of RAPD variation in heterogeneous, outcrossing species. We describe the population genetic variation of RAPD markers in natural, diploid sources of dioecious buffalograss [Buchloe dactyloides (Nutt.) Engelm.]. Buffalograss is native to the semi-arid regions of the Great Plains of North America, where it is important for rangeland forage, soil conservation, and as turfgrass. Most sources of buffalograss germplasm are polyploid; diploid populations are previously known only from semi-arid Central Mexico. This is the first report of diploids from humid Gulf Coastal Texas. These two diploid sources represent divergent adaptive ecotypes. Seven 10-mer primers produced 98 polymorphic banding sites. Based on the presence/ absence of bands, a genetic distance matrix was calculated. The new Analysis of Molecular Variance (AMOVA) technique was used to apportion the variation among individuals within populations, among populations within adaptive regions, and among regions. There was considerable variation within each of the four populations, and every individual was genetically distinct. Even so, genetic divergence was found among local populations. Within-population variation was larger and among-population variation smaller in Mexico than in Texas. The largest observed genetic differences were those between the two regional ecotypes. These patterns of genetic variation were very different from those reported for inbred species and provide important baseline data for cultivar identification and continuing studies of the evolution of polyploid races in this species.

Journal ArticleDOI
TL;DR: This paper found that the appropriateness of faceto-face and meetings did not change over time, whereas ratings of phone and text (to some extent) and new media did.
Abstract: monwus solution. Multidimensional scaling placed tmditwnal media in separate clusters, and new media together with some instances of text and phone, along interpersonalmediated and synchronous-asynchronous axes. The appropriateness of faceto-face and meetings did not change over time, whereas ratings of phone and text (to some extent) and new media did. Appropriateness of new media was weakly associated with use. Finally, there was very little evidence of social infonnafwn processing influence on appropriateness, except for organizational newwmm’ mtings of the newest medium, desktop video.

Journal ArticleDOI
TL;DR: The characterization of the Aequorea victoria GFP chromophore is described, which is released as a hexapeptide upon digestion of the protein with papain, formed upon cyclization of the residues Ser-dehydroTyr-Gly within the polypeptide.
Abstract: The green-fluorescent proteins (GFP) are a unique class of proteins involved in bioluminescence of many cnidaria. The GFPs serve as energy-transfer acceptors, receiving energy from either a luciferase-oxyluciferin complex or a Ca(2+)-activated photoprotein, depending on the organism. Upon mechanical stimulation of the organism, GFP emits green light spectrally identical to its fluorescence emission. These highly fluorescent proteins are unique due to the nature of the covalently attached chromophore, which is composed of modified amino acid residues within the polypeptide. This report describes the characterization of the Aequorea victoria GFP chromophore which is released as a hexapeptide upon digestion of the protein with papain. The chromophore is formed upon cyclization of the residues Ser-dehydroTyr-Gly within the polypeptide. The chromophore structure proposed here differs from that described by Shimomura [(1979) FEBS Lett. 104, 220] in a number of ways.

Journal ArticleDOI
TL;DR: Empirical evidence indicates that, on average, IT investments are zero net present value NPV investments; they are worth as much as they cost; innovative IT investments, however, increase the value of the firm.
Abstract: Determining whether investments in information technology IT have an impact on firm performance has been and continues to be a major problem for information systems researchers and practitioners. Financial theory suggests that managers should make investment decisions that maximize the value of the firm. Using event-study methodology, we provide empirical evidence on the effect of announcements of IT investments on the market value of the firm for a sample of 97 IT investments from the finance and manufacturing industries from 1981 to 1988. Over the announcement period, we find no excess returns for either the full sample or for any one of the industry subsamples. However, cross-sectional analysis reveals that the market reacts differently to announcements of innovative IT investments than to followup, or noninnovative investments in IT. Innovative IT investments increase firm value, while noninnovative investments do not. Furthermore, the market's reaction to announcements of innovative and noninnovative IT investments is independent of industry classification. These results indicate that, on average, IT investments are zero net present value NPV investments; they are worth as much as they cost. Innovative IT investments, however, increase the value of the firm.

Journal ArticleDOI
TL;DR: The principle is proposed to explain the constructive process of information seeking and use bringing affective considerations to what has usually been regarded as a cognitive process.
Abstract: This paper proposes an uncertainty principle for information seeking. The principle is based on the results of a series of studies conducted by the author into the user's perspective of the information search process. A basic principle of uncertainty is elaborated by six corollaries. The principle is proposed to explain the constructive process of information seeking and use bringing affective considerations to what has usually been regarded as a cognitive process.

Journal ArticleDOI
TL;DR: The data implicate osteopontin as a potentially important mediator of arterial neointima formation as well as dystrophic calcification that often accompanies this process.
Abstract: In an earlier report, we used differential cloning to identify genes that might be critical in controlling arterial neointima formation (Giachelli, C., N. Bae, D. Lombardi, M. Majesky, and S. Schwartz. 1991. Biochem. Biophys. Res. Commun. 177:867-873). In this study, we sequenced the complete cDNA and conclusively identified one of these genes, 2B7, as rat osteopontin. Using immunochemistry and in situ hybridization, we found that medial smooth muscle cells (SMC) in uninjured arteries contained very low levels of osteopontin protein and mRNA. Injury to either the adult rat aorta or carotid artery using a balloon catheter initiated a qualitatively similar time-dependent increase in both osteopontin protein and mRNA in arterial SMC. Expression was transient and highly localized to neointimal SMC during the proliferative and migratory phases of arterial injury, suggesting a possible role for osteopontin in these processes. In vitro, basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta), and angiotensin II (AII), all proteins implicated in the rat arterial injury response, elevated osteopontin expression in confluent vascular SMC. Finally, we found that osteopontin was a novel component of the human atherosclerotic plaque found most strikingly associated with calcified deposits. These data implicate osteopontin as a potentially important mediator of arterial neointima formation as well as dystrophic calcification that often accompanies this process.

Journal ArticleDOI
TL;DR: A method is introduced for the solution of the electronic-structure problem in the independent-electron approximation based upon a variational solution for the density matrix, which is truncated to zero beyond a real-space radius R c and becomes exact as R c →∞.
Abstract: We introduce a method for the solution of the electronic-structure problem in the independent-electron approximation The method is based upon a variational solution for the density matrix, which is truncated to zero beyond a real-space radius ${\mathit{R}}_{\mathit{c}}$, and becomes exact as ${\mathit{R}}_{\mathit{c}}$\ensuremath{\rightarrow}\ensuremath{\infty} Most importantly, the computer time scales only linearly with system size The method is tested in the context of tight-binding models in one and three dimensions

Journal ArticleDOI
16 Apr 1993-Science
TL;DR: A phylogenetic framework inferred from comparisons of small subunit ribosomal RNA sequences describes the evolutionary origin and early branching patterns of the kingdom Animalia and shows the animal lineage is monophyletic and includes choanoflagellates.
Abstract: A phylogenetic framework inferred from comparisons of small subunit ribosomal RNA sequences describes the evolutionary origin and early branching patterns of the kingdom Animalia. Maximum likelihood analyses show the animal lineage is monophyletic and includes choanoflagellates. Within the metazoan assemblage, the divergence of sponges is followed by the Ctenophora, the Cnidaria plus the placozoan Trichoplax adhaerens, and finally by an unresolved polychotomy of bilateral animal phyla. From these data, it was inferred that animals and fungi share a unique evolutionary history and that their last common ancestor was a flagellated protist similar to extant choanoflagellates.

Journal ArticleDOI
David Popenoe1
TL;DR: Stacey and Cowan as mentioned in this paper argued that families have lost functions power and authority that familism as a cultural value has diminished and that people have become less willing to invest time money and energy in family life turning instead to investments in themselves.
Abstract: Contrary to the view of some academics that the family in America is not declining but just changing the thesis of this article is that family decline since 1960 has been extraordinarily steep and its social consequences serious especially for children. Drawing mainly on U.S. Census data family trends of the past three decades are reviewed. The evidence for family decline is appraised in three areas: demographic institutional and cultural. It is argued that families have lost functions power and authority that familism as a cultural value has diminished and that people have become less willing to invest time money and energy in family life turning instead to investments in themselves. Comments by Norval D. Glenn Judith Stacey and Philip A. Cowan and a reply by Popenoe are included (pp. 542-55). (EXCERPT)

Journal ArticleDOI
TL;DR: It is shown that the nonlinear energy-tracking signal operator Psi and its discrete-time counterpart can estimate the amplitude envelope of AM signals and the instantaneous frequency of FM signals.
Abstract: It is shown that the nonlinear energy-tracking signal operator Psi (x)=(dx/dt)/sup 2/-xd/sup 2/x/dt/sup 2/ and its discrete-time counterpart can estimate the AM and FM modulating signals. Specifically, Psi can approximately estimate the amplitude envelope of AM signals and the instantaneous frequency of FM signals. Bounds are derived for the approximation errors, which are negligible under general realistic conditions. These results, coupled with the simplicity of Psi , establish the usefulness of the energy operator for AM and FM signal demodulation. These ideas are then extended to a more general class of signals that are sine waves with a time-varying amplitude and frequency and thus contain both an AM and an FM component; for such signals it is shown that Psi can approximately track the product of their amplitude envelope and their instantaneous frequency. The theoretical analysis is done for both continuous- and discrete-time signals. >

Journal ArticleDOI
TL;DR: The properties of trivalent and hexavalent chromium are reviewed with respect to acute and chronic oral toxicity, dermal toxicity, systemic toxicity, toxicokinetics, cytotoxicity, genotoxicity and carcinogenicity.
Abstract: The properties of trivalent and hexavalent chromium are reviewed with respect to acute and chronic oral toxicity, dermal toxicity, systemic toxicity, toxicokinetics, cytotoxicity, genotoxicity and carcinogenicity. The hexavalent chromium compounds appear to be 10-100 times more toxic than the trivalent chromium compounds when both are administered by the oral route. Dermal irritancy and allergy are more frequently caused by contact with soluble hexavalent chromium compounds. The cytotoxicity of soluble and insoluble hexavalent chromium compounds to fibroblasts is 100-1000 times greater than that demonstrated by trivalent chromium compounds. In short-term tests, the hexavalent chromium compounds demonstrated genotoxic effects four times more frequently than did the trivalent chromium compounds. Carcinogenicity appears to be associated with the inhalation of the less soluble/insoluble hexavalent chromium compounds. The toxicology of chromium does not reside with the elemental form. It varies greatly among a wide variety of very different chromium compounds. Oxidation state and solubility are particularly important factors in considering the toxicity of chromium with respect to its chemical speciation.