bluuebunny/crossref_metadata_2025_split huggingface dataset:
Imputation of missing values in the case of a multiple item instrument measuring alcohol consumption
Authors: Gmel Gerhard 
Published: August 2002

AbstractMissing values in survey instruments are a common problem for survey researchers. It is aggravated in the case of instruments used to measure alcohol consumption: they usually consist of item batteries from which summary measures, such as grams of pure alcohol per day, are constructed, and a missing value (for example, quantity or frequency) in regard to a single item for only one of several beverages results in a missing summary measure across all of the beverages, though the values for the remaining items are known. The present paper examines different approaches to imputation of missing values, feasible with standard statistical software packages. Hot‐deck imputation is shown to have certain advantages, but even single‐value imputation (for example, median imputation) results in values that are comparable to those of the other three imputation methods. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of an adjusted chi‐square statistic as applied to observational studies involving clustered binary data
Authors: Jung Sin‐Ho , Ahn Chul , Donner Allan 
Published: August 2002

AbstractA simple adjustment to the Pearson chi‐square test has been proposed for comparing proportions estimated from clustered binary observations. However, the assumptions needed to assure the validity of this test have not yet been thoroughly addressed. These assumptions will hold for experimental comparisons, but could be violated for some observational comparisons. In this paper we investigate the conditions under which the adjusted chi‐square statistic is valid and examine its performance when these assumptions are violated. We also introduce some alternative test statistics that do not require these assumptions. The test statistics considered are then compared through simulation and an example presented based on real data. The simulation study shows that the adjusted chi‐square statistic generally produces empirical type I errors close to nominal under the assumption of a common intracluster correlation coefficient. Even if the intracluster correlations are different, the adjusted chi‐square statistic performs well when the groups have equal numbers of clusters. Copyright © 2001 John Wiley & Sons, Ltd.
How does institutional change affect heterogeneity among firms?
Authors: Walker Gordon , Madsen Tammy L. , Carini Gary 
Published: August 2002

AbstractThis paper examines the variation in performance of incumbents and entrants following the deregulation of prices and entry in the airline industry. Our approach is similar to earlier studies of interfirm performance heterogeneity across industries. Drawing on theories of industry evolution, we hypothesize that the performance of entrants will have higher variance than incumbents. Further, given the opportunities offered by price deregulation, we propose that incumbents will have higher variance in performance under deregulation than in the earlier regime. The findings indicate that entrant performance heterogeneity is significantly greater than incumbent performance heterogeneity following deregulation, but that the variation in performance among incumbents does not significantly change when deregulation occurs. The second result is surprising given the range of service and process innovations that incumbents initiated. These results suggest that the distinction between entrants and incumbents is critical to future studies of performance variation within and across industries. Copyright © 2002 John Wiley & Sons, Ltd.
Emergent maintenance of ERP: new roles and relationships
Authors: Hirt Sabine Gabriele , Swanson E. Burton 
Published: August 2002

AbstractHow a firm supports its enterprise resource planning system after putting it into production, when its maintenance may be said to be emergent, is critical to the benefits it will eventually derive. Here we report a longitudinal case study of one firm's emergent maintenance of its SAP R/3 system. The study reveals that maintenance‐related roles and relationships differ substantively from those typical of traditional maintenance. We view this firm's maintenance practices to be a harbinger of broader and longer‐term change in maintaining application portfolios. We suggest that the roles and relationships involved are likely to be more complex and therefore more varied in organizational form. In particular, we anticipate: (1) greater sharing of the maintenance task among more participants, with the firm's users often assuming the lead, supported by vendors and third parties; (2) the IS department often playing a more limited, but still key role in providing a portfolio's ongoing support services; and (3) a contingency approach to maintenance, the best approach being a function of specific organizational and systems circumstances. Copyright © 2001 John Wiley & Sons, Ltd.
Management observation and communication theory and organizational information
Authors: Swanson G. A. 
Published: August 2002

AbstractThe identification of basic principles that apply to all aspects of the knowledge domain of a discipline is important. Such fundamentals define the discipline and instruct its development. This process, nevertheless, may be pursued too narrowly—and schools of management thought often do so. These schools of thought generally seek principles and methods that apply equally in all different kinds of organizations. In doing so, they ignore an important aspect of the objects they observe, that organizations are part of a highly dynamic, currently ongoing, evolutionary process. Relatively recent emergents, exchange‐based societies are composed of organizations competing for survival with dynamic, ever‐changing internal purposes and external goals. The competition itself is management and unique management patterns emerge in different organizations. Management science needs a conceptual framework that instructs the development of organization‐specific management theories. Management observation and communication theory (MOCT) is one step in this direction.MOCT is essentially an integration of linguistic–mathematical theory (L‐M theory) and living systems theory (LST). L‐M theory is a pure system—defined by the interrelationships of its own elements, and thus does not depend on any particular empirical element. LST views existence in the context of concrete systems and particularly from the vantage of living systems. By integrating these general systems theories, MOCT instructs the discovery and development of internal purposes and external goals unique to particular organizations. L‐M theory synthesizes information about an organization's internal processes into general statements of purposes and connects those statements to similarly general statements of external goals. LST focuses MOCT on the processes and structures managers control and in which they compete.This paper overviews the central ideas and methods of MOCT. Some examples of methods suggested by the theory are given to illustrate how MOCT is applied. Copyright © 2001 International Society for the Systems Sciences.
Laparoscopic total mesorectal excision with autonomic nerve preservation
Authors: Weiser Martin R. , Milsom Jeffrey W. 
Published: August 2002

AbstractLaparoscopy has greatly influenced abdominal surgery. We hypothesize that the benefits of minimally invasive surgery are applicable to rectal cancer. A cadaver model of laparoscopic rectal resection with total mesorectal excision (TME) and autonomic nerve preservation was utilized to explore this hypothesis. The principles of TME were followed, including high vascular ligation, sharp mesorectal dissection, and identification and preservation of the autonomic pelvic nerves. After proving feasibility in the cadaver model, a clinical study was performed on patients with mid to low rectal cancers. We observed acceptable morbidity with this minimally invasive technique of rectal resection and TME. We conclude that there is growing evidence that laparoscopic methods can be applied to patients with rectal cancer. Semin. Surg. Oncol. 19:396–403, 2000. © 2000 Wiley‐Liss, Inc.
Chronic treatment with imipramine or mirtazapine antagonizes stress‐ and FG7142‐induced increase in cortical norepinephrine output in freely moving rats
Authors: Dazzi Laura , Ladu Stefania , Spiga Francesca , Vacca Giada , Rivano Antonella , Pira Luigi , Biggio Giovanni 
Published: August 2002

AbstractThe effect of repeated administration of imipramine or mirtazapine, two antidepressant drugs with different mechanisms of action, was studied on the stress‐induced increase in the extracellular concentration of norepinephrine in the prefrontal cortex of freely moving rats. Exposure to footshock in control rats induced a marked increase in extracellular norepinephrine concentrations in the prefrontal cortex (+120%). Long‐term administration with imipramine or mirtazapine (10 mg/kg, i.p., twice or once a day, respectively, for 14 days) reduced (+50%) the effect of stress on basal norepinephrine output. Acute administration of FG7142 (30 mg/kg, i.p.), an anxiogenic benzodiazepine receptor inverse agonist, induced a marked increase in norepinephrine output (+90%) in control rats. In rats chronically treated with imipramine or mirtazapine this effect was completely antagonized. On the contrary, acute administration of these antidepressant drugs failed to reduce stress‐ and FG7142‐induced increase in norepinephrine output. The plastic changes in the sensitivity of norepinephrine neurons to footshock stress and drug‐induced anxiogenic stimuli may reveal a new important neuronal mechanism involved in the long‐term modulation of emotional state. This action might be relevant for the anxiolytic and antidepressant effect of antidepressant drugs. Synapse 43:70–77, 2002. © 2001 Wiley‐Liss, Inc.
Enhancement of presynaptic performance in transgenic Drosophila overexpressing heat shock protein Hsp70
Authors: Karunanithi Shanker , Barclay Jeffrey W. , Brown Ian R. , Robertson R. Meldrum , Atwood Harold L. 
Published: August 2002

AbstractPrior heat shock confers protection to Drosophila synapses during subsequent heat stress by stabilizing quantal size and reducing the decline of quantal emission at individual synaptic boutons. The major heat shock protein Hsp70, which is strongly induced by high temperatures in Drosophila, may be responsible for this synaptic protection. To test this hypothesis, we investigated synaptic protection and stabilization at larval neuromuscular junctions of transgenic Drosophila which produce more than the normal amount of Hsp70 in response to heat shock. Overexpression of Hsp70 coincides with enhanced protection of presynaptic performance, assayed by measuring mean quantal content and percentage success of transmission. Quantal size was not selectively altered, indicating no effects of overexpression on postsynaptic performance. Thus, presynaptic mechanisms can be protected by manipulating levels of Hsp70, which would provide stability to neural circuits otherwise susceptible to heat stress. Synapse 44:8–14, 2002. © 2002 Wiley‐Liss, Inc.
Loss of metabolites from monkey striatum during PET with FDOPA
Authors: Cumming Paul , Munk Ole Lajord , Doudet Doris 
Published: August 2002

AbstractThe decarboxylation of 6‐[18F]fluorodopa (FDOPA) and retention of the product [18F]fluorodopamine within vesicles of catecholamine fibers results in the labeling of dopamine‐rich brain regions during FDOPA/PET studies. However, this metabolic trapping is not irreversible due to the eventual diffusion of [18F]fluorodopamine metabolites from brain. Consequently, time–radioactivity recordings of striatum are progressively influenced by metabolite loss. In linear analyses, the net blood–brain clearance of FDOPA (K, ml g−1 min−1) can be corrected for this loss by the elimination rate constant k (min−1). Similarly, the DOPA decarboxylation rate constant (k, min−1) calculated by compartmental analysis can also be corrected for metabolite loss by the elimination rate constant k (min−1). To compare the two methods, we calculated the two elimination rate constants using data recorded during 240 min of FDOPA circulation in normal monkeys and in monkeys with unilateral 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) lesions. Use of the extended models increased the magnitudes of K and k in striatum; in the case of k, variance of the estimate was substantially improved upon correction for metabolite loss. The rate constants for metabolite loss were higher in MPTP‐lesioned monkey striatum than in normal striatum. The high correlation between individual estimates of k and k suggests that both rate constants reveal loss of decarboxylated metabolites from brain. Synapse 41:212–218, 2001. © 2001 Wiley‐Liss, Inc.
GABAergic neurons in prepositus hypoglossi regulate REM sleep by its action on locus coeruleus in freely moving rats
Authors: Kaur Satvinder , Saxena R.N. , Mallick Birendra N. 
Published: August 2002

AbstractGABA in locus coeruleus modulates REM sleep. Apart from the presence of interneurons, locus coeruleus also receives GABAergic inputs from prepositus hypoglossi in the medulla, where the presence of REM‐ON‐like neurons have been reported. Therefore, it was hypothesized that GABAergic projections from prepositus hypoglossi to locus coeruleus may modulate REM sleep. The experiments were conducted on chronic rats prepared for recording EEG, EOG, and EMG in freely moving conditions. Bipolar stimulating electrodes were implanted in prepositus hypoglossi bilaterally, while chemitrodes were implanted bilaterally in locus coeruleus. The prepositus hypoglossi were bilaterally stimulated (3 Hz, 250 μsec, 100 μA) for 8 h in the presence and absence of picrotoxin (0.25 μg/250 nl) microinjection bilaterally in locus coeruleus, followed by poststimulation recording for 4 h. It was observed that stimulation of prepositus hypoglossi alone significantly increased REM sleep primarily by increasing the REM sleep duration per episode. However, when it was stimulated in the presence of picrotoxin in LC, REM sleep decreased, predominantly due to decreased REM sleep duration per episode. The results of this study suggest that GABAergic inputs from prepositus hypoglossi act on locus coeruleus and regulate REM sleep, possibly by inhibition of REM‐OFF neurons. Synapse 42:141–150, 2001. © 2001 Wiley‐Liss, Inc.
Energy appproach in peformance‐based seismic design of steel moment resisting frames for basic safety objective
Authors: Akbas B. , Shen J. , Hao H. 
Published: August 2002

AbstractThis study presents an energy approach to the performance‐based seismic design of steel moment resisting frames for the basic safety objective. The seismic demand is expressed in terms of hysteresis energy and its distribution along the height of the frame, based on an associated study. The resistance of a steel moment‐resisting frame to such demand is presented in the form of energy dissipation capacities of critical members, based on the previous experimental studies on full‐scale moment‐connections. An energy‐based design methodology is proposed for performance‐based earthquake resistant design. The proposed design method is examined using design examples and the results are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Cytotoxic and genotoxic effects of As, MMA, and DMA on leukocytes and stimulated human lymphocytes
Authors: Sordo Monserrat , Herrera Luis A. , Ostrosky‐Wegman Patricia , Rojas Emilio 
Published: August 2002

AbstractInorganic arsenic is a human carcinogen associated with different types of cancer. Arsenic metabolism produces two methylated species: monomethylarsonic and dimethylarsinic acids. Although this metabolic route has been involved in arsenic detoxification, it is still not clear whether these methylated metabolites participate in the carcinogenic process. In this work, we studied the cytotoxic and genotoxic effects of arsenic and its metabolites. Cytotoxicity was evaluated in cultured lymphocytes from three donors. Mitotic and replication indices were the parameters analyzed. The results indicate a clear cytotoxic effect by sodium arsenite but not by its metabolites. Genotoxicity was assessed by the single cell gel electrophoresis assay. Sodium arsenite increased DNA migration in stimulated lymphocytes only at doses greater than 5 × 10–6 M; meanwhile in leukocytes a weak response was observed. Monomethylarsonic acid produced in leukocytes a weak induction of DNA damage, while in stimulated lymphocytes, a dose‐increase in DNA migration was observed. The injury caused by dimethylarsinic acid was more evident than that observed in cultures treated with sodium arsenite and monomethylarsonic acid in stimulated lymphocytes, although in leukocytes no effect on DNA migration was found. In conclusion, only sodium arsenite had the capacity to alter mitotic and replication indices, while sodium arsenite and its metabolites were capable of inducing single strand DNA breaks on stimulated human lymphocytes treated in vitro for 24 h; however, the differences observed were between individual responses, one donor being more susceptible even at the lower doses. This individual susceptibility to arsenic compounds has been repeatedly observed for different end‐points and should be studied further. Teratogenesis Carcinog. Mutagen. 21:249–260, 2001. © 2001 Wiley‐Liss, Inc.
Protective effect of Picroliv, the active constituent of Picrorhiza kurroa, against chemical carcinogenesis in mice
Authors: Rajeshkumar N.V. , Kuttan Ramadasan 
Published: August 2002

AbstractCancer chemoprevention of chemically induced tumours by Picroliv, an iridoid glycoside mixture purified from Picrorhiza kurroa, was studied on 20‐methylcholanthrene (20‐MC)‐induced sarcoma model and 7,12‐dimethylbenz[a]anthracene (DMBA)‐initiated papilloma formation in BALB/c mice. Administration of Picroliv (100 and 200 mg/kg, p.o) inhibited the sarcoma development by 47 and 53% as estimated on day 200 after 20‐MC administration. Control animals started dying of tumour burden 76 days after 20‐MC administration and all animals were dead by day 170, while 60 and 66% of the animals survived in the Picroliv treated group, 100 and 200 mg/kg, respectively. Picroliv exhibited anti‐tumour‐promoting activity on a two‐stage carcinogenesis test on mouse skin using DMBA as an initiator and croton oil as a promoter. Topical application of Picroliv (1 and 5 mg/mouse) 30 minutes prior to that of croton oil application resulted in a 50 and 60% reduction in the number of animals that developed papillomas, and 48 and 64% reduction in the number of papillomas per mouse. There was also a delay in the onset of first skin tumour in the group of animals treated with Picroliv. Oral administration of Picroliv (150 mg/kg, p.o.) prior to DMBA application delayed the onset of papillomas and the percent of mice (60%) with tumours indicates that Picroliv inhibited the tumour initiation induced by DMBA. Picroliv administration was also found to increase the life span of transplanted Dalton’s Lymphoma Ascites (DLA) and Ehrlich Ascites Carcinoma (EAC) harboring mice and reduced the volume of transplanted solid tumours. Teratogenesis Carcinog. Mutagen. 21:303–313, 2001. © 2001 Wiley‐Liss, Inc.
The science/technology interaction: Implications for science literacy
Authors: Cajas Fernando 
Published: August 2002

AbstractScience literacy includes understanding technology. This raises questions about the role of technology in science education as well as in general education. To explore these questions, this article begins with a brief history of technology education as it relates to science education and discusses how new conceptions of science and technological literacy are moving beyond the dichotomies that formerly characterized the relationship between science and technology education. It describes how Benchmarks for Science Literacy, the National Science Education Standards, and the Standards for Technological Literacy have been making a case for introducing technology studies into general education. Examples of specific technological concepts fundamental for science literacy are provided. Using one example from the design of structures, the article examines how understanding about design (i. e., understanding constraints, trade‐offs, and failures) is relevant to science literacy. This example also raises teaching and learning issues, including the extent to which technology‐based activities can address scientific and technological concepts. The article also examines how research can provide guides for potential interactions between science and technology and concludes with reflections on the changes needed, such as the creation of curriculum models that establish fruitful interactions between science and technology education, for students to attain an understanding of technology. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 715–729, 2001
Update on new developments in the study of human teratogens
Authors: Shepard T.H. , Brent R.L. , Friedman J.M. , Jones K.L. , Miller R.K. , Moore C.A. , Polifka J.E. 
Published: August 2002

AbstractBackground and MethodsThe purpose of this annual article is to highlight and briefly review new and significant information on agents that may be teratogenic in pregnant women. Various sources of on‐line and printed information are given.ResultsThe following topics have been discussed: 1) lithium medication: decreased estimate of risk; 2) cigarette smoking and genotype as contributors to oral‐facial clefts and clubfoot; 3) trimethoprim; 4) methimazole syndrome?; 5) glucocorticoids and oral‐facial clefts; 6) binge drinking; 7) fetal valproate syndrome; and 8) carbamazepine.ConclusionsWe have highlighted several maternal exposures during pregnancy that are associated with small but increased rates of birth defects, generally only a few cases per 1,000 infants. These exposures include cigarette smoking, and treatment with lithium, trimethoprim, methimazole, or corticosteroids. This weak teratogenic effect was usually identified by the linkage of an uncommon treatment with an unusual birth defect outcome. The use of modern epidemiologic techniques, especially prospective multicenter studies that provide increased numbers, has helped to strengthen the evidence for these associations. We discuss how teratogenic risks that are small in comparison to the background risk can be presented to at‐risk women and their doctors. We have briefly listed some elements that might be used in prioritizing further studies of suspected teratogenic exposures. Various existing methods for expressing the strength of evidence for human teratogenicity are also given. Teratology 65:153–161, 2002. © 2002 Wiley‐Liss, Inc.
Hypercompetition and the future of global management in the twenty‐first century
Authors: Harvey Michael , Novicevic Milorad M. , Kiessling Timothy 
Published: August 2002

AbstractIn today's hypercompetitive landscape, organizations are moving from being multinational to being global
in the strategic intent. There are a number of “drivers” of this globalization process, but it would
be difficult to argue that globalization is not going to be an enduring phenomena. The consequences of this
modification in the strategic orientation of organizations have implications for most every element in an
organization. To gain an insight into the future of global organizations in the twenty‐first century, a
market‐based perspective is utilized. In addition, the importance of organizational boundary spanners is
also explored as a means to effectively compete in the global competitive arena. Inpatriation is viewed as a
means to gain tacit knowledge at the headquarters level to ensure adaptation of corporate standard operating
policies to effectively compete as a global network, yet with the flexibility to meet local competitor
strategies and consumer demands. © 2001 John Wiley & Sons, Inc.