Showing papers by "University of Pennsylvania published in 1994"
Posted Content•
TL;DR: The authors describes the advantages of these studies and suggests how they can be improved and also provides aids in judging the validity of inferences they draw, such as multiple treatment and comparison groups and multiple pre- or post-intervention observations.
Abstract: Using research designs patterned after randomized experiments, many recent economic studies examine outcome measures for treatment groups and comparison groups that are not randomly assigned. By using variation in explanatory variables generated by changes in state laws, government draft mechanisms, or other means, these studies obtain variation that is readily examined and is plausibly exogenous. This paper describes the advantages of these studies and suggests how they can be improved. It also provides aids in judging the validity of inferences they draw. Design complications such as multiple treatment and comparison groups and multiple pre- or post-intervention observations are advocated.
7,222 citations
Abstract: Considerable progress has been made in identifying market-driven businesses, understanding what they do, and measuring the bottom-line consequences of their orientation to their markets. The next c...
6,313 citations
Tohoku University1, University of Zurich2, Lawrence Berkeley National Laboratory3, Stanford University4, College of William & Mary5, University of Urbino6, CERN7, Budker Institute of Nuclear Physics8, University of California, Irvine9, Cornell University10, Argonne National Laboratory11, ETH Zurich12, Tata Institute of Fundamental Research13, Hillsdale College14, Spanish National Research Council15, Ohio State University16, University of Notre Dame17, Kent State University18, University of California, San Diego19, University of California, Berkeley20, University of Minnesota21, University of Alabama22, University of Helsinki23, Los Alamos National Laboratory24, California Institute of Technology25, George Washington University26, Syracuse University27, Lawrence Livermore National Laboratory28, Oklahoma State University–Stillwater29, University of Washington30, Max Planck Society31, Boston University32, University of California, Los Angeles33, Royal Holloway, University of London34, Université Paris-Saclay35, University of Pennsylvania36, University of Illinois at Urbana–Champaign37, University of Bristol38, University of Tokyo39, University of Delaware40, Carnegie Mellon University41, University of California, Santa Cruz42, Karlsruhe Institute of Technology43, Heidelberg University44, Florida State University45, University of Mainz46, University of Edinburgh47, Brookhaven National Laboratory48, Durham University49, University of Lausanne50, Massachusetts Institute of Technology51, University of Southampton52, Nagoya University53, University of Oxford54, Northwestern University55, University of British Columbia56, Columbia University57, Lund University58, University of Sheffield59, University of California, Santa Barbara60, Iowa State University61, University of Alberta62, University of Cambridge63
TL;DR: This biennial Review summarizes much of Particle Physics using data from previous editions, plus 2205 new measurements from 667 papers, and features expanded coverage of CP violation in B mesons and of neutrino oscillations.
Abstract: This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 2205 new measurements from 667 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. This edition features expanded coverage of CP violation in B mesons and of neutrino oscillations. For the first time we cover searches for evidence of extra dimensions (both in the particle listings and in a new review). Another new review is on Grand Unified Theories. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.
5,143 citations
Thomas Jefferson University1, Harvard University2, Scripps Health3, University of Pittsburgh4, University of British Columbia5, Memorial Hospital of South Bend6, Yale University7, Arizona Heart Institute8, University of Toronto9, St Lukes Episcopal Hospital10, Johns Hopkins University11, Lenox Hill Hospital12, University of Pennsylvania13, University of Texas at San Antonio14, Cleveland Clinic15
TL;DR: In selected patients, placement of an intracoronary stent, as compared with balloon angioplasty, results in an improved rate of procedural success, a lower rate of angiographically detected restenosis, a similar rate of clinical events after six months, and a less frequent need for revascularization of the original coronary lesion.
Abstract: Background Coronary-stent placement is a new technique in which a balloon-expandable, stainless-steel, slotted tube is implanted at the site of a coronary stenosis. The purpose of this study was to compare the effects of stent placement and standard balloon angioplasty on angiographically detected restenosis and clinical outcomes. Methods We randomly assigned 410 patients with symptomatic coronary disease to elective placement of a Palmaz-Schatz stent or to standard balloon angioplasty. Coronary angiography was performed at base line, immediately after the procedure, and six months later. Results The patients who underwent stenting had a higher rate of procedural success than those who underwent standard balloon angioplasty (96.1 percent vs. 89.6 percent, P = 0.011), a larger immediate increase in the diameter of the lumen (1.72 ±0.46 vs. 1.23 ±0.48 mm, P<0.001), and a larger luminal diameter immediately after the procedure (2.49 ±0.43 vs. 1.99 ±0.47 mm, P<0.001). At six months, the patients with stented ...
4,300 citations
27 Jun 1994
Abstract: This paper will focus on the semantic representation of verbs in computer systems and its impact on lexical selection problems in machine translation (MT). Two groups of English and Chinese verbs are examined to show that lexical selection must be based on interpretation of the sentences as well as selection restrictions placed on the verb arguments. A novel representation scheme is suggested, and is compared to representations with selection restrictions used in transfer-based MT. We see our approach as closely aligned with knowledge-based MT approaches (KBMT), and as a separate component that could be incorporated into existing systems. Examples and experimental results will show that, using this scheme, inexact matches can achieve correct lexical selection.
3,492 citations
Posted Content•
TL;DR: The authors examined the role of relationship lending in small firm finance and found that borrowers with longer banking relationships pay lower interest rates and are less likely to pledge collateral, consistent with theoretical arguments that relationship lending generates valuable information about borrower quality.
Abstract: This paper examines the role of relationship lending in small firm finance. We examine price and nonprice terms of bank lines of credit (L/C) extended to small firms. Our focus on bank L/Cs allows us toe examine a type of loan contract in which the bank-borrower relationship is likely to be an important mechanism for solving asymmetric information problems associated with financing small enterprises. We find that borrowers with longer banking relationships pay lower interest rates and are less likely to pledge collateral. These results are consistent with theoretical arguments that relationship lending generates valuable information about borrower quality.
2,928 citations
TL;DR: The authors investigates circumstances under which accruals are predicted to improve earnings' ability to measure firm performance, as reflected in stock returns, and the results of empirical tests are consistent with these predictions.
2,892 citations
Journal Article•
TL;DR: It is demonstrated that a temperature-sensitive p53 induces temperature-dependent decreases in the expression of the apoptosis-suppressing gene bcl-2 in the murine leukemia cell M1, while simultaneously stimulating increases in theexpression of bax, a gene which encodes a dominant-inhibitor of the Bcl-1 protein.
Abstract: The p53 tumor suppressor gene product can induce apoptotic cell death through an unknown mechanism. Here we demonstrate that a temperature-sensitive p53 induces temperature-dependent decreases in the expression of the apoptosis-suppressing gene bcl-2 in the murine leukemia cell M1, while simultaneously stimulating increases in the expression of bax, a gene which encodes a dominant-inhibitor of the Bcl-2 protein. Mice deficient in p53 exhibit increases in Bcl-2 and decreases in Bax protein levels in several tissues as determined by immunohistochemical and immunoblot methods. The findings suggest a potential mechanism by which p53 regulates apoptosis, as well as responses to radiation and chemotherapeutic drugs in cancer.
2,179 citations
TL;DR: The major RNA-binding motifs are described and examples of how they may function are given.
Abstract: In eukaryotic cells, a multitude of RNA-binding proteins play key roles in the posttranscriptional regulation of gene expression. Characterization of these proteins has led to the identification of several RNA-binding motifs, and recent experiments have begun to illustrate how several of them bind RNA. The significance of these interactions is reflected in the recent discoveries that several human and other vertebrate genetic disorders are caused by aberrant expression of RNA-binding proteins. The major RNA-binding motifs are described and examples of how they may function are given.
1,886 citations
TL;DR: In this paper, the authors suggest that earnings announcements provide information that allows certain traders to make judgements about a firm's performance that are superior to the judgements of other traders, and that there may be more information asymmetry at the time of an announcement than in nonannouncement periods.
1,790 citations
TL;DR: Approaches for improving recombinant adenoviruses that are based on further crippling the virus to limit expression of nondeleted viral genes are suggested.
Abstract: An important limitation that has emerged in the use of adenoviruses for gene therapy has been loss of recombinant gene expression that occurs concurrent with the development of pathology in the organ expressing the transgene. We have used liver-directed approaches to gene therapy in mice to study mechanisms that underlie the problems with transient expression and pathology that have characterized in vivo applications of first-generation recombinant adenoviruses (i.e., those deleted of E1a and E1b). Our data are consistent with the following hypothesis. Cells harboring the recombinant viral genome express the transgene as desired; however, low-level expression of viral genes also occurs. A virus-specific cellular immune response is stimulated that leads to destruction of the genetically modified hepatocytes, massive hepatitis, and repopulation of the liver with nontransgene-containing hepatocytes. These findings suggest approaches for improving recombinant adenoviruses that are based on further crippling the virus to limit expression of nondeleted viral genes.
TL;DR: The Disgust Scale as mentioned in this paper is a measure of individual differences in disgust sensitivity and includes two true-false and two disgust-rating items for each of seven domains of disgust elicitors (food, animals, body products, sex, body envelope violations, death, and hygiene) and for a domain of magical thinking (via similarity and contagion) that cuts across the 7 domains of elicitors.
TL;DR: In this article, Alice asked the Cheshire Cat to tell her which way she ought to go from here, and the Cat said that depends a good deal on where you want to get to, and then it doesn't matter which way you go.
Abstract: “Would you tell me, please, which way I ought to go from here?” Alice asked the Cheshire Cat. “That depends a good deal on where you want to get to,” said the Cat. “I don't much care where...” said Alice. “Then it doesn't matter which way you go,” said the Cat. (Carroll, 1983: 72)
TL;DR: It is reported here that stem cells isolated from testes of donor male mice will repopulate sterile testes when injected into seminiferous tubules and may prove useful as a tool for biomedical science and biotechnology.
Abstract: In the adult male, a population of diploid stem-cell spermatogonia continuously undergoes self-renewal and produces progeny cells, which initiate the complex process of cellular differentiation that results in mature spermatozoa. We report here that stem cells isolated from testes of donor male mice will repopulate sterile testes when injected into seminiferous tubules. Donor cell spermatogenesis in recipient testes showed normal morpholigical characteristics and produced mature spermatozoa. This methodology, besides opening new avenues of basic research into spermatogenesis and stem-cell self-renewal, may prove useful as a tool for biomedical science and biotechnology.
TL;DR: It is concluded that the requirement to learn and remember two rules is not in itself sufficient to account for the poor performance of the younger children in the experimental condition.
TL;DR: The objective of this study was to assess objectively the ability of observers to assess body condition of dairy cows and the relationship between body region description and absolute body condition score.
TL;DR: The authors reviewed insights into second-language (L2) learning that have been revealed through over a decade of research on the social interaction and negotiation of L2 learners and their interlocutors, beginning with the seminal work of Hatch (1978a, 197810) and Long (1980 et.
Abstract: This article reviews insights into second-language (L2) learning that have been revealed through over a decade of research on the social interaction and negotiation of L2 learners and their interlocutors, begining with the seminal work of Hatch (1978a, 197810) and Long (1980 et passim), and withereferenceto a corpus of informal, experimental, and classroom data from published studies. This research illustrates ways in which negotiation contributes to condi- tions, processes, and outcomes ofL2 learningby facilitating learners' comprehension and structural segmentation of L2 input, access to lexical form and meaning, and production of modified output. The research points out areas in which negotiation does not appear to assist L2 learning, especially with respect to the learner's need to access L2
TL;DR: Verbal memory, as a primary neuropsychological deficit present early in the course of schizophrenia, implicates the left temporal-hippocampal system.
Abstract: Background: Medication and chronicity have complicated past attempts to characterize the neuropsychological performance of patients with schizophrenia. There have been inconsistencies regarding the pattern, selectivity, and sources of observed deficits. Our objective was to comprehensively examine neuropsychological function in patients with schizophrenia who had never been exposed to neuroleptic medication, and who were experiencing their first episode (FE) of psychosis. Methods: Subjects were consecutive recruitments that included 37 patients with FE schizophrenia who were never exposed to neuroleptics. These subjects were compared with 65 unmedicated, previously treated (PT) patients and 131 healthy controls. Results: The patient groups had nearly identical profiles showing generalized impairment, particularly in verbal memory and learning, attention-vigilance, and speeded visual-motor processing and attention. Verbal memory and learning accounted for most of the variance between patients and controls and removing this effect substantially attenuated all other differences. By contrast, both the FE group and PT group continued to show highly significant deficits in verbal memory and learning after controlling for attention, abstraction, and all other functions. Some functions not typically implicated in schizophrenia (spatial cognition, fine motor speed, and visual memory) were more impaired in the PT group than in the FE group. Conclusions: Verbal memory, as a primary neuropsychological deficit present early in the course of schizophrenia, implicates the left temporal-hippocampal system. Neuropsychological evaluations before treatment permit differentiation of primary deficits from changes secondary to medication or chronicity. This is essential for developing a neurobehavioral perspective on schizophrenia.
TL;DR: In this paper, a stochastic dynamic programming model is used to model the operating flexibility of a multinational corporation to shift production between two manufacturing plants located in different countries, the value of which is dependent upon the real exchange rate.
Abstract: The multinational corporation is a network of activities located in different countries. The value of this network derives from the opportunity to benefit from uncertainty through the coordination of subsidiaries which are geographically dispersed. We model this coordination as the operating flexibility to shift production between two manufacturing plants located in different countries. A stochastic dynamic programming model treats explicitly this flexibility as equivalent to owning an option, the value of which is dependent upon the real exchange rate. The model is extended to analyze hysteresis effects and within-country growth options. We show that the management of across-border coordination has led to changes in the heuristic rules used for performance evaluation and transfer pricing.
TL;DR: A protracted infusion of fluorouracil during pelvic irradiation improved the effect of combined-treatment postoperative adjuvant therapy in patients with high-risk rectal cancer.
Abstract: Background The combination of radiation therapy and chemotherapy with fluorouracil plus semustine after surgery has been established as an effective approach to decreasing the risk of tumor relapse and improving survival in patients with rectal cancer who are at high risk for relapse or death. We sought to determine whether the efficacy of chemotherapy could be improved by administering fluorouracil by protracted infusion throughout the duration of radiation therapy and whether the omission of semustine would reduce the toxicity and delayed complications of chemotherapy without decreasing its antitumor efficacy. Methods Six hundred sixty patients with TNM stage II or III rectal cancer received intermittent bolus injections or protracted venous infusions of fluorouracil during postoperative radiation to the pelvis. They also received systemic chemotherapy with semustine plus fluorouracil or with fluorouracil alone in a higher dose, both before and after the pelvic irradiation. Results With a median follow-...
TL;DR: After the presence of microsatellites in Arabidopsis and their utility for genetic mapping had been demonstrated, systematic screening for (CA)n and (GA)n sequences was carried out on marker-selected plasmid libraries and a small-insert genomic library.
TL;DR: In this paper, the authors examined the relationship between interfirm cooperation and the innovation output of startup firms in the biotechnology industry and found that cooperation affects innovation, but only a reciprocal relationship was established.
Abstract: This paper examines the association between interfirm cooperation and the innovation output of startup firms in the biotechnology industry. A reciprocal association is hypothesized. The results, however, show only that cooperation affects innovation. Several control variables are related to cooperation and innovation, especially the startup's position in the cooperative network.
TL;DR: It is reported here that testis-derived cells transplanted into the testis of an infertile mouse will colonize seminiferous tubules and initiate spermatogenesis in > 70% of recipients and with recipients that maintained endogenous sperMatogenesis, testis cell transplantation yielded mice in which up to 80% of progeny were sired by donor-derived spermatozoa.
Abstract: Spermatogenesis is a complex, highly organized, very efficient process that is based upon the capacity of stem cell spermatogonia simultaneously to undergo self-renewal and to provide progeny that differentiate into mature spermatozoa. We report here that testis-derived cells transplanted into the testis of an infertile mouse will colonize seminiferous tubules and initiate spermatogenesis in > 70% of recipients. Testis-derived cells from newborn mice were less effective in colonizing recipient testes than cells from 5- to 15- or 21- to 28-day-old mice. Increasing the number of Sertoli cells in the donor cell population did not increase the efficiency of colonization. Unmodified embryonic stem cells were not able to substitute for testis-derived cells in colonizing testes but instead formed tumors in syngeneic as well as nonsyngeneic hosts. Finally, with recipients that maintained endogenous spermatogenesis, testis cell transplantation yielded mice in which up to 80% of progeny were sired by donor-derived spermatozoa. The technique of spermatogonial cell transplantation should provide a means to generate germline modifications in a variety of species following development of spermatogonial culture techniques and should have additional applications in biology, medicine, and agriculture.
TL;DR: These studies demonstrate that CAM blockade can effectively inhibit inflammation; however, there appear to be clear differences in the adhesion requirements for particular types of inflammation.
Abstract: Neutrophil-endothelial cell interactions are mediated by interacting sets of cell adhesion molecules (CAMs) and chemoattractant/activator molecules to form an "adhesion cascade." The initial phase of inflammation, a transient slowing of neutrophils in postcapillary venules, is mediated by selectins. Subsequently, firm adhesion of neutrophils to the vessel wall occurs via interaction of the CD11/CD18 (beta 2) integrins to endothelial ligands such as intercellular adhesion molecule-1 (ICAM-1). This binding requires activation of CD11/CD18 by exposure of the neutrophil to a variety of activating/chemoattractant molecules, such as platelet-activating factor or interleukin-8. Finally, transmigration into tissues occurs, a process that requires both a chemotactic stimulus and engagement of platelet-endothelial cell adhesion molecule-1 (PECAM-1). Several approaches have been used to probe the role of CAMs in vivo. These include the use of blocking antibodies, chimeric selectin-immunoglobulin proteins, sialyl Lewisx oligosaccharides and peptides, along with the study of humans and animals with genetically determined adhesion deficiencies. These studies demonstrate that CAM blockade can effectively inhibit inflammation; however, there appear to be clear differences in the adhesion requirements for particular types of inflammation. By understanding the CAM/chemoattractant profiles involved in specific disease states, it may be possible to precisely and effectively target therapy to a wide variety of inflammatory diseases.
08 Mar 1994
TL;DR: The Penn Treebank has recently implemented a new syntactic annotation scheme, designed to highlight aspects of predicate-argument structure as discussed by the authors, which incorporates a more consistent treatment of a wide range of grammatical phenomena, provides a set of coindexed null elements in what can be thought of as "underlying" position for phenomena such as wh-movement, passive, and the subjects of infinitival constructions, and allows for a clear, concise tagging system for some semantic roles.
Abstract: The Penn Treebank has recently implemented a new syntactic annotation scheme, designed to highlight aspects of predicate-argument structure. This paper discusses the implementation of crucial aspects of this new annotation scheme. It incorporates a more consistent treatment of a wide range of grammatical phenomena, provides a set of coindexed null elements in what can be thought of as "underlying" position for phenomena such as wh-movement, passive, and the subjects of infinitival constructions, provides some non-context free annotational mechanism to allow the structure of discontinuous constituents to be easily recovered, and allows for a clear, concise tagging system for some semantic roles.
TL;DR: The treatment of bipolar illness could be enhanced by public health efforts to promote early diagnosis and treatment; ensuring adequate trials of mood-stabilizers for patients with frequent recurrences; further research on bipolar disorder with prominent anxiety symptoms; and improved access to mental health care.
TL;DR: PPAR gamma is present at low levels in 3T3-L1 preadipocytes and is induced dramatically during adipocyte conversion using either normal differentiating conditions or the PPAR activator, WY-14,643.
Abstract: Activators of peroxisome proliferator activated receptor (PPAR) regulate fatty acid metabolism and can induce adipocyte differentiation. We show here that the gamma subtype of PPAR is expressed at high levels in adipose tissue in contrast to a variety of other tissues, where little gene expression was noted. In addition, PPAR gamma is present at low levels in 3T3-L1 preadipocytes and is induced dramatically during adipocyte conversion using either normal differentiating conditions (fetal calf serum, dexamethasone, isobutyl-methylxanthine, and insulin) or the PPAR activator, WY-14,643. Thus PPAR gamma may be important for adipose cell development and function.
TL;DR: This paper investigated the relationship between two industry characteristics, technology and growth, and organizational culture by comparing the cultures of organizations within and across industries, and found that stable organizational culture dimensions existed and varied more across industries than within them.
Abstract: This study investigated the relationship between two industry characteristics, technology and growth, and organizational culture. We examined this relationship by comparing the cultures of organizations within and across industries. Using 15 firms representing four industries in the service sector, we found that stable organizational culture dimensions existed and varied more across industries than within them. Specific cultural values were associated with levels of industry technology and growth. One implication of this finding is that the use of organizational culture as a competitive advantage may be more constrained than researchers and practitioners have suggested.
TL;DR: In this article, the effects of secondary doping on polyaniline and its derivatives are shown to be based primarily on a change in molecular conformation of the polymer from "compact coil" to "expanded coil".
TL;DR: This article investigated the benefits and detriments of emotional and task-related conflict in work groups and found that emotional conflict was negatively associated with group performance and satisfaction, while task conflict was positively associated with the group performance.
Abstract: This study investigates the benefits and detriments of emotional and task‐related conflict in work groups. Group value consensus (GVC), or the extent to which group members share values, and group value fit (GVF), or the degree to which the culture of the group matches the ideal culture envisioned by external parties with control over the group, are hypothesized to decrease conflict. In examining 88 workgroups performing comparable organizational tasks, it was found that groups with low levels of value similarity among members and between the group and governing superiors had higher levels of conflict than groups with high levels of value similarity. As hypothesized, emotional conflict was negatively associated with group performance and satisfaction, while task conflict was positively associated with group performance. The implications of these results for conflict management and group effectiveness are discussed.