bluuebunny/crossref_metadata_2025 huggingface dataset:
A Bayesian analysis of a proportion under non‐ignorable non‐response
Authors: Nandram Balgobin , Choi Jai Won
Published: August 2002

The National Health Interview Survey (NHIS) is one of the surveys used to assess one aspect of the health status of the U.S. population. One indicator of the nation's health is the total number of doctor visits made by the household members in the past year. We study the binary variable of at least one doctor visit versus no doctor visit by all household members to each of the 50 states and the District of Columbia. The proportion of households with at least one doctor visit is an indicator of the status of health of the U.S. population. There is a substantial number of non‐respondents among the sampled households. The main issue we address here is that the non‐response mechanism should not be ignored because respondents and non‐respondents differ. The purpose of this work is to estimate the proportion of households with at least one doctor visit, and to investigate what adjustment needs to be made for non‐ignorable non‐response. We consider a non‐ignorable non‐response model that expresses uncertainty about ignorability through the ratio of odds of a household doctor visit among respondents to the odds of doctor visit among all households, and this ratio varies from state to state. We use a hierarchical Bayesian selection model to accommodate this non‐response mechanism. Because of the weak identifiability of the parameters, it is necessary to ‘borrow strength’ across states as in small area estimation. We also perform a simulation study to compare the expansion model with an alternative expansion model, an ignorable model and a non‐ignorable model. Inference for the probability of a doctor visit is generally similar across the models. Our main result is that for some of the states the non‐response mechanism can be considered non‐ignorable, and that 95 per cent credible intervals of the probability for a household doctor visit and the probability that a household responds shed important light on the NHIS data. Copyright 2002 © John Wiley & Sons, Ltd.
Modification of the sample size and the schedule of interim analyses in survival trials based on data inspections
Authors: Schäfer Helmut , Müller Hans‐Helge
Published: August 2002

A method is presented which allows us to adapt the sample size as well as the number and time points of interim analyses to the treatment difference observed at an interim look during the course of a clinical trial with censored survival time as the endpoint. The method allows the inclusion of data inspections during the course of the trial and redesign of the trial on the basis of the observed treatment difference without affecting the type I error risk. Formulae for recalculating the required number of events and the number of further patients to be randomized as a function of the observed hazard rates and the detectable hazard ratio are given. Copyright © 2001 John Wiley & Sons, Ltd.
Diffusion and prediction of Leishmaniasis in a large metropolitan area in Brazil with a Bayesian space–time model
Authors: Assunção Renato M. , Reis Ilka A. , Oliveira Claudia Di Lorenzo
Published: August 2002

We present results from an analysis of human visceral Leishmaniasis cases based on public health records of Belo Horizonte, Brazil, from 1994 to 1997. The main emphasis in this study is on the development of a spatial statistical model to map and project the rates of visceral Leishmaniasis in Belo Horizonte. The model allows for space–time interaction and it is based on a hierarchical Bayesian approach. We assume that the underlying rates evolve in time according to a polynomial trend specific to each small area in the region. The parameters of these polynomials receive a spatial distribution in the form of an autonormal distribution. While the raw rates are extremely noisy and inadequate to support decisions, the resulting smoothed rates estimates are considerably less affected by small area issues and provide very clear directions to implement public health actions. Copyright © 2001 John Wiley & Sons, Ltd.
Sex differences in cortisol excretion during anticipation of a psychological stressor: possible support for the tend–and–befriend hypothesis
Authors: Ennis Michael , Kelly Kimberly S. , Lambert Paul L.
Published: August 2002

The present experiment tested the hypothesis that differential neuroendocrine elicitation is prompted by subjects' cognitive expectations of an anticipated stressor. Subjects making a ‘threat appraisal’ of an academic examination were predicted to have increased hypothalamic–pituitary–adrenal (HPA) activation, while activation was expected to be unchanged in subjects making a ‘challenge appraisal.’ Self‐reported anxiety in relation to these variables was also examined. HPA activation was assessed by urinary cortisol at baseline (at least 1 week before the examination) and at pre‐test (immediately before the examination). Contrary to the hypothesis, there was an unexpected sex × time interaction that was particularly robust in subjects making a challenge appraisal. Males in the challenge appraisal group had a significant increase in cortisol excretion from baseline to pre‐test, with greater reported anxiety than the threat appraisal group. In contrast, females had a decrease in cortisol excretion that was significant for only the challenge appraisal group, although reported anxiety between the challenge and threat groups was not different. Results may support the recent proposition that the female stress response has evolved differently than that of males, or they may reflect sex differences in production of corticosteroid‐binding globulin. Copyright © 2001 John Wiley & Sons, Ltd.
The impact of market liberalization on vertical scope: the case of Argentina
Authors: Toulan Omar N.
Published: August 2002

This paper analyzes the impact of market liberalization on the vertical scope of firms. Using the case of Argentina, it is shown how the opening of the economy can improve contracting abilities and heighten competition, increasing the ability and incentive of firms to outsource. Survey findings support the main hypothesis as well as the specific importance of reforms relating to inflation, import costs, and heightened demand standards in increasing the use of outsourcing. A case study of the steel producer Siderar, highlights that while firms may reduce their presence in peripheral activities, they may also increase their presence in core areas so as to increase their value proposition. Copyright © 2002 John Wiley & Sons, Ltd.
Function‐point analysis using design specifications based on the Unified Modelling Language
Authors: Uemura Takuya , Kusumoto Shinji , Inoue Katsuro
Published: August 2002

Function‐point analysis was introduced to help measure the functionality of software systems. For more than a decade, function points have been widely used to measure the size of information systems, often as a part of estimating the effort required for software development and maintenance processes. Limiting the use of function point measurement have been concerns about variable judgements on the part of the personnel doing the measurement, yielding differences in function‐point measures for the same software product even in the same organization. Also, if an organization tries to introduce function‐point analysis, the process normally starts with measurements from the organization's own past software products—a time consuming task with start‐up costs. In this paper, we propose detailed function‐point analysis measurement rules using design specifications based on the Unified Modelling Language and describe a function‐point measurement tool, whose inputs are design specifications developed on Rational Rose®. Then in this paper, we report tool validation work on software involved in software evolution at an organization where we have applied the tool to actual design specifications and examined the differences between the function point values obtained by the tool and those of an experienced function point measurement specialist at the organization. Copyright © 2001 John Wiley & Sons, Ltd.
A decision framework for enterprise resource planning maintenance and upgrade: A client perspective
Authors: Ng Celeste See Pui
Published: August 2002

Over the last decade, many large organizations have been shifting from developing their own information system (IS) to licensing and installing large software packages known as enterprise resource planning (ERP) systems. These organizations now face the challenge of maintaining these costly systems and many are about to make their first upgrade decisions. The study reported herein aims to address the following research questions from the ERP‐client perspective: (1) What are the fundamental factors driving ERP maintenance and upgrade decisions? (2) How do these factors differ from those for traditional custom, in‐house software? and (3) Do existing software and hardware replacement models suffice for ERP maintenance and upgrade decision modeling? A single case study method and empirical data analysis were conducted and are presented here. We observe that ERP maintenance and upgrade characteristics are indeed unique in three ways: (1) most organizations maintain and upgrade their ERP systems in order to realize increased business benefits from the systems; (2) a new version upgrade reduces the number of ERP‐client‐done enhancement modifications; and (3) a new version upgrade potentially reduces future legal change patch (LCP) maintenance distributed by the ERP vendor. It was also found that on average LCP maintenance is almost as costly as user enhancements. Based on these findings, we conclude that the existing in‐house software and hardware replacement models are insufficient for ERP situations. We propose a preliminary ERP decision model that overcomes the observed insufficiencies. Copyright © 2001 John Wiley & Sons, Ltd.
Coordinating distributed components on the web: an integrated development environment
Authors: Fuentes Lidia , Troya José María
Published: August 2002

Component‐based software has become an important alternative for building applications, especially distributed ones, so it is essential to define new software development processes based on components. Within this trend, we propose a complete framework‐based method which guides application developers in exactly determining application requirements. It also guides how to build them using the compositional framework MultiTEL from the collaborative and multimedia applications domain. Although many multimedia frameworks are available, none of them offer a design methodology for understanding and adapting the framework classes or components to each derived application. By applying an architecture description language (ADL) we are able to document the framework and help designers in: constructing; reusing, and connecting components; extending the framework architecture; and adding components to meet user requirements. Tools for the automatic generation of code from the ADL specifications are also described. Copyright © 2001 John Wiley & Sons, Ltd.
A hybrid software process simulation model
Authors: Donzelli Paolo , Iazeolla Giuseppe
Published: August 2002

This paper deals with simulation modeling of software processes and proposes the combination of three traditional modeling methods (analytical, continuous and discrete‐event) into a unique hybrid two‐level modeling approach. At the higher abstraction level, the process is modeled by a discrete‐event queuing network, which represents the component activities (i.e. service stations), their interactions, and the exchanged artifacts. The implementation details of the introduced activities are given at the lower abstraction level, where the analytical and continuous methods are used. The proposed approach is applied to a waterfall‐based software process to study the effects of requirements instability on various process quality attributes, as effort, delivery time, productivity, rework percentage and product quality. Simulation results show that the use of the model can provide both qualitative and quantitative suggestions on how to change the software process to improve its quality or to achieve specific organizational goals. The model is primarily designed to represent the behavior of hypothetical projects, to allow researchers to view the implications of their assumptions. However, with small improvements, it can be extended to become a tool for analyzing and predicting the behavior of actual projects. Copyright © 2001 John Wiley & Sons, Ltd.
Observation of the breast cancer patient with a tumor‐positive sentinel node: Implications of the ACOSOG Z0011 trial
Authors: Grube Baiba J. , Giuliano Armando E.
Published: August 2002

Axillary lymph node status has been the most important prognostic factor for breast cancer throughout the past century. During the past decade, intraoperative lymphatic mapping with sentinel lymph node dissection (SLND) has been investigated as an alternative staging modality. This technique may be as accurate as ALND, and certainly is less invasive. Adjuvant treatment recommendations, which historically were made on the basis of lymph node status alone, now take into account primary tumor features, molecular markers, and patient characteristics. This evolution of current treatment patterns is driven in part by the diminishing size of tumors, the simultaneous decrease in the presence of axillary metastases, and a better understanding of tumor‐specific risk factors. How do these trends affect the interpretation of a tumor‐positive sentinel node (SN)? Can an axilla with a positive SN be observed? Should it be observed? This review examines the implications of a positive SN in the context of smaller tumor size, decreased nodal disease, and increased reliance on alternative prognostic factors for treatment decisions. The historical data comparing ALND to no ALND in clinically node‐negative patients is reviewed and discussed in the context of observation for a positive SN. These are the issues underlying the ACOSOG Z0010 and Z0011 trials. Semin. Surg. Oncol. 20:230–237, 2001. © 2001 Wiley‐Liss, Inc.
Adjuvant therapy for resectable rectal adenocarcinoma
Authors: Hu Kenneth S. , Harrison Louis B.
Published: August 2002

The mainstay of treatment for rectal cancer over the past 100 years has been surgical resection. However, for the majority of rectal cancers treated conventionally by resection alone, locoregional recurrence is the major mode of failure. Over the past several decades, significant progress has been made in developing effective adjuvant regimens. In the United States, postoperative chemoradiation is standard treatment for T3 or node‐positive patients. However, preoperative radiation with or without chemotherapy decreases local recurrence, increases sphincter preservation, and may improve survival. The purpose of this article is to review the role of adjuvant therapy in resectable rectal cancers and to update the status of ongoing randomized trials. Semin. Surg. Oncol. 19:336–349, 2000. © 2000 Wiley‐Liss, Inc.
Efficiency of a simple approach to damper allocation in MDOF structures
Authors: Lopez Garcia D. , Soong T. T.
Published: August 2002

A simple approach to the design of optimal damper configurations has recently been suggested. This practical method is designated simplified sequential search algorithm (SSSA). Although some comparisons showed that the efficiency of the SSSA is similar to that of more sophisticated methods, a more comprehensive investigation is needed in order to gain more insight into its effectiveness. In this study, the SSSA is applied to several regular building models with different natural periods, numbers of storeys, levels of added damping, and different ground motions. Only one type of passive energy dissipation device is considered: linear viscous dampers. It is concluded that, in the case of regular buildings, the SSSA will generally lead to efficient damper configurations, particularly for low‐to‐medium‐rise buildings and for a number of dampers equal to or greater than 1.5–2 times the number of storeys. The resulting damper configurations are found to be sensitive to ground motion characteristics, especially for low levels of supplemental damping. Copyright © 2002 John Wiley & Sons, Ltd.
Software model checking: extracting verification models from source code†
Authors: Holzmann Gerard J. , H. Smith Margaret
Published: August 2002

To formally verify a large software application, the standard method is to invest a considerable amount of time and expertise into the manual construction of an abstract model, which is then analysed for its properties by either a mechanized or a human prover. There are two problems with this approach. The first problem is that this verification method can be no more reliable than the humans that perform the manual steps. If the average rate of error for human work is a function of the problem size, this holds not only for the construction of the original application, but also for the construction of the model. The standard verification trajectory therefore tends to become less reliable for larger applications. The second problem is one of timing and relevance. Software applications built by teams of programmers can change rapidly, often daily. Manually constructing an accurate abstraction of any one version of the application, though, can take weeks, which may jeopardize the validity of the results. In this paper a different verification method that avoids these problems is discussed. This method, which may be the precursor of a new class of testing techniques, was originally developed to allow for a thorough testing of parts of the software of a new commercial telephone switch. Here it is argued, though, that the method also has broad applicability to distributed software systems design in general.
Excitatory and inhibitory responses of dopamine neurons in the ventral tegmental area to nicotine
Authors: Erhardt Sophie , Schwieler Lilly , Engberg Göran
Published: August 2002

In the present electrophysiological study the mechanisms by which nicotine activates dopamine neurons in the ventral tegmental area in anesthetized Sprague‐Dawley rats were analyzed. Intravenous administration of nicotine caused a dose‐dependent increase in firing rate and percentage of spikes fired in bursts of ventral tegmental area dopamine neurons. However, this activation was preceded by an instantaneous but short‐lasting inhibition of the firing rate. The excitation of dopamine neurons by nicotine (1.5–400 μg/kg i.v.) was antagonized and even reversed into an inhibitory response by elevated levels (four‐fold) of the endogenous glutamate receptor antagonist kynurenic acid, as induced by a potent inhibitor of kynurenine 3‐hydroxylase (PNU 156561A, 40 mg/kg, i.v., 5–9 h). The antagonistic action induced by PNU 156561A pretreatment was prevented by administration of D‐cycloserine (128 mg/kg, i.v., 5 min). Administration of the GABAB‐receptor antagonist CGP 35348 (200 mg/kg, i.v., 3 min) facilitated the nicotine‐induced increase in burst firing activity of dopamine neurons and antagonized the short‐lasting decrease in firing rate by nicotine. The results of the present study show that nicotine produces both inhibition and excitation of ventral tegmental area dopamine neurons, actions that appear to be related to the release of GABA and glutamate, respectively. Whereas the excitatory action of nicotine may be associated with motivational processes underlying learning and cognitive behavior, the inhibitory action of the drug may play a more prominent role in the situation of a profound dysregulation of the mesocorticolimbic dopamine system and may help to explain the high prevalence of tobacco‐smoking in schizophrenics. Synapse 43:227–237, 2002. © 2002 Wiley‐Liss, Inc.
Temporal profiling of methamphetamine‐induced changes in gene expression in the mouse brain: Evidence from cDNA array
Authors: Cadet Jean Lud , Jayanthi Subramaniam , Mccoy Michael T. , Vawter Marquis , Ladenheim Bruce
Published: August 2002

Methamphetamine (METH) is a neurodegenerative drug of abuse. Its toxicity is characterized by destruction of monoaminergic terminals and by apoptosis in cortical and striatal cell bodies. Multiple factors appear to control METH neurotoxicity, including free radicals and transcription factors. Here, using cDNA arrays, we show the temporal profile of gene expression patterns in the cortex of mice treated with this drug. We obtained two patterns of changes from 588 genes surveyed. First, an early pattern is characterized by upregulation of transcription factors, including members of the jun family. Second, a delayed pattern includes genes related to cell death and to DNA repair. A number of trophic factors were also activated at the later timepoint. These observations suggest that METH can activate a multigene machinery that participates in the production of its toxic effects. The resulting degenerative effects of the drug are thus the result of a balance between protoxic and antiapoptotic mechanisms triggered by its administration to these animals. These observations are of clinical relevance because of the recent identification of degenerative changes in the brains of METH abusers. Synapse 41:40–48, 2001. © 2001 Wiley‐Liss, Inc.
Acute neuroleptic stimulates DOPA decarboxylase in porcine brain in vivo
Authors: Danielsen Erik H. , Smith Donald , Hermansen Flemming , Gjedde Albert , Cumming Paul
Published: August 2002

The activity of DOPA decarboxylase measured in homogenates from rat striatum, or calculated from the rate of tracer decarboxylation measured ex vivo, is stimulated following acute treatment with antagonists of dopamine D2‐like receptors. We used compartmental kinetics to test the hypothesis that utilization of the DOPA decarboxylase substrate [18F]fluorodopa is potentiated in living striatum following acute treatment with a typical neuroleptic. The kinetics of the tracer uptake were determined in eight anesthetized female pigs (40 kg) and in three animals receiving an infusion of haloperidol (75 μg kg−1 h−1) for 1 h prior to tracer administration and throughout the 2‐h positron emission recording. The relative activity of DOPA decarboxylase in striatum was increased threefold by the treatment. This potentiation of DOPA decarboxylation after pharmacological blockade of dopamine D2‐like receptors may be used to optimize the utilization of exogenous DOPA in the treatment of Parkinson's disease. Synapse 41:172–175, 2001. © 2001 Wiley‐Liss, Inc.
Defective hippocampal mossy fiber long‐term potentiation in endothelial nitric oxide synthase knockout mice
Authors: Doreulee Nanuli , Brown Ritchie E. , Yanovsky Yevgeni , Gödecke Axel , Schrader Jürgen , Haas Helmut L.
Published: August 2002

Mossy fiber long‐term potentiation (mfLTP) was compared in hippocampal slices prepared from wild‐type mice and mice lacking functional endothelial nitric oxide synthase (eNOS‐/‐ mice) using field potential recording. In the presence of D‐2‐amino‐5‐phosphonovaleric acid (AP5, 50 μM), the mfLTP induced by tetanic stimulation (100 Hz, 1 sec) was significantly reduced in knockouts (n = 8) in comparison with wild‐type (n = 8). Similarly, potentiation induced by forskolin (30 μM) or 8‐bromo‐cyclic adenosine monophosphate (8‐Br‐cAMP, 100 μM) was less pronounced in knockouts. However, in wild‐types the mfLTP‐induced in the presence of the nonselective pharmacological inhibitor of NOS (N‐nitro‐L‐Arginine, 100 μM, n = 6) was not significantly different from control (n = 8). Thus, eNOS is not directly involved in mfLTP, but lack of eNOS during development leads to a deficit downstream of adenylyl cyclase. Synapse 41:191–194, 2001. © 2001 Wiley‐Liss, Inc.
Retrofit of pre‐Northridge steel moment‐resisting frames using fluid viscous dampers
Authors: Uriz P. , Whittaker A. S.
Published: August 2002

This paper describes a study of the use of linear fluid viscous damping devices for the seismic retrofit of a three‐storey, pre‐Northridge steel‐framed building. Four part‐perimeter moment frames resisted lateral forces in the building. One of the four perimeter frames was analysed using static pushover, incremental dynamic and nonlinear dynamic analysis to calculate likely beam plastic rotations in design and maximum earthquakes. Ten 10–50 (design) and two 2–50 (maximum) earthquake histories were used for the nonlinear dynamic analysis. The maximum beam plastic rotations exceeded 0·020 radian for some of the design‐earthquake histories and 0·045 radian for one of the maximum‐earthquake histories. Fluid viscous dampers were added to the frame using the procedures of FEMA 273 with the goal of eliminating plastic rotations in the beams of the frame in the design earthquake. Average reductions in the displacement of the frame by a factor exceeding 2 were achieved in the design earthquake with the addition of approximately 40% equivalent viscous damping. Although plastic rotations in the beams were substantially reduced, they were not eliminated for 7 of the 10 characterizations of the design earthquake; the calculated maximum beam plastic rotations exceeded the measured plastic rotation capacity of pre‐Northridge steel moment‐frame connections and so some fractures of the beam connections in this frame would not be unexpected. The addition of the dampers to the building frame led to substantial increases in the maximum base shear and column axial forces, which in practice would likely lead to strengthening of the columns and the foundations. The average maximum axial forces in the dampers calculated by response‐history analysis exceeded the values calculated using the first‐mode procedure of FEMA 273. Higher‐mode effects must be considered using either response‐history analysis or the procedures of FEMA 274 to adequately size and detail fluid viscous dampers and their connections to the structural framing. Copyright © 2001 John Wiley & Sons, Ltd.
Examination of Alternaria alternata mutagenicity and effects of nitrosylation using the Ames Salmonella test
Authors: Schrader T. J. , Cherry W. , Soper K. , Langlois I. , Vijay H.M.
Published: August 2002

Molds of the genus Alternaria are common food pathogens responsible for the spoilage of fruits, vegetables, grains, and nuts. Although consumption of Alternaria alternata‐contaminated foodstuffs has been implicated in an elevated incidence of esophageal carcinogenesis, the mutagenic potencies of several A. alternata toxins seem unable to account for the levels of activity found using crude mycelial extracts. In this study, the mutagenic effects of nitrosylation were examined with the major Alternaria metabolites Altenuene (ALT), Alternariol (AOH), Alternariol Monomethyl Ether (AME), Altertoxin I (ATX I), Tentoxin (TENT), Tenuazonic Acid (TA), and Radicinin (RAD) using the Ames Salmonella strains TA98 and TA100. In the absence of nitrosylation, ATX I was mutagenic when tested from 1 to 100 μg/plate in TA98 with rat liver S9 for activation, while AOH and ATX I were weakly mutagenic ± S9 in TA100. Incubation with nitrite generally increased mutagenic potencies with ATX I strongly mutagenic ± S9 in both TA98 and TA100, while ALT, AOH, AME, and RAD responses were enhanced in TA100 + S9. However, subsequent examination of three extracts made from A. alternata culture broth, acetone‐washed mycelia, and the acetone washes showed a different mutagenic response with both broth and acetone washes directly mutagenic in TA98 and TA100 but with a reduced response + S9. The acetone‐washed mycelial extract was found to have the lowest mutagenic activity of the three extracts tested. Nitrosylation had little effect on the mutagenicity of any of the extracts. Thus, while nitrosylation increases the mutagenicity of ATX I, and to a lesser extent that of several other Alternaria toxins, the results demonstrate that Alternaria produces a major mutagenic activity with a S. typhimurium response different from that found with the purified toxins. Efforts are currently underway to chemically identify this mutagenic species. Teratogenesis Carcinog. Mutagen. 21:261‐274, 2001. Published 2001 Wiley‐Liss, Inc.
Cytogenetic study of chronic ethanol consumption in rats
Authors: Tavares D.C. , Cecchi A.O. , Jordão A.A. , Vannucchi H. , Takahashi C.S.
Published: August 2002

Ethanol was supplied in the drinking water of Wistar rats at a concentration of 20% v/v for up to 30 days. The animals treated with ethanol demonstrated a nonsignificant increase in chromosomal aberration frequency when compared with control animals. The mitotic index values obtained indicated no significant differences between ethanol treatment and control groups. The final weights of control rats were significantly greater than those of the ethanol‐treated group. Chronic administration of ethanol showed no clastogenic or cytotoxic effect. After chronic ethanol consumption, the cytochromes P450 activity increases, thus possibly preventing the ethanol that has entered the circulation from reaching excessive levels, leading to metabolic adaptation and/or tolerance. Teratogenesis Carcinog. Mutagen. 21:361–368, 2001. © 2001 Wiley‐Liss, Inc.
Comparing the epistemological underpinnings of students' and scientists' reasoning about conclusions
Authors: Hogan Kathleen , Maglienti Mark
Published: August 2002

This study examined the criteria that middle school students, nonscientist adults, technicians, and scientists used to rate the validity of conclusions drawn by hypothetical students from a set of evidence. The groups' criteria for evaluating conclusions were considered to be dimensions of their epistemological frameworks regarding how knowledge claims are justified, and as such are integral to their scientific reasoning. Quantitative and qualitative analyses revealed that the responses of students and nonscientists differed from the responses of technicians and scientists, with the major difference being the groups' relative emphasis on criteria of empirical consistency or plausibility of the conclusions. We argue that the sources of the groups' differing epistemic criteria rest in their different spheres of cultural practice, and explore implications of this perspective for science teaching and learning. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 663–687, 2001
Science education in urban settings: Seeking new ways of praxis through critical ethnography
Authors: Barton Angela Calabrese
Published: August 2002

The challenges faced in urban science education are deeply rooted in the ongoing struggle for racial, class and gender equity. Part of this struggle is tied to huge differences in class and involves making more equitable the distribution of resources. Another part of this struggle is tied to the rich diversity of children who attend urban schools and involves generating new ways of understanding, valuing, and genuinely incorporating into school‐based practices the culture, language, beliefs, and experiences that these children bring to school. Thus, this article argues that to address these two challenges—and indeed to achieve a more just science education for all urban students— explicitly political research methodologies must be considered and incorporated into urban education. One potential route for this is critical ethnography, for this kind of methodology emerges collaboratively from the lives of the researcher and the researched and is centrally about praxis and a political commitment to the struggle for liberation and in defense of human rights. In making this argument, I have drawn from stories from my own research with homeless children. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 899–917, 2001
Young women's scientific identity formation in an urban context
Authors: Brickhouse Nancy W. , Potter Jennifer T.
Published: August 2002

In this article we examine the scientific identity formation of two young women of color who attend an urban vocational high school. One young woman lives in an urban setting, while the other lives in a suburban setting. We describe how these young women's identities influence and respond to experiences in school science. In particular, we describe how the experience of marginalization can make membership in a school science community impossible or undesirable. We also describe the advantages that accrue to students who fit well with the ideal identities of an urban school. Finally, we describe some of the difficulties students face who aspire to scientific or technological competence yet do not desire to take on aspects of the identities associated with membership in school science communities. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 965–980, 2001
International expansion of e‐retailers: Where the Amazon flows
Authors: Chakrabarti Rajesh , Scholnick Barry
Published: August 2002

Competition among e‐retailers is becoming increasingly intense and continuously narrowing margins. We
examine the price competition between Amazon and Barnes & Noble to illustrate this. The key to survival,
therefore, lies in rapidly expanding market size in one or both of two ways: expansion across product lines and
international expansion. Although foreign consumers can easily access an online retailer's website, high
cross‐border shipping costs often put foreign e‐retailers at a disadvantage. We show how, in spite of
being a superior store in most respects, Amazon fails to compete with the leading Canadian online book retailer,
Chapters Online, primarily because of cross‐border shipping disadvantages. Consequently e‐retailers
are using traditional foreign direct investment (FDI)‐based strategies to expand internationally.
In addition, a new mode of foreign market entry—e‐mediation—involving match‐making between
customers and suppliers in a country through a website located in another country, is also emerging. This is
particularly suitable in situations where protectionist barriers forbid FDI‐based strategies. Amazon plans to
use this strategy in Canada. © 2002 John Wiley & Sons, Inc.
Co‐production of microcystins and aeruginopeptins by natural cyanobacterial bloom
Authors: Harada Ken‐ichi , Mayumi Tsuyoshi , Shimada Takayuki , Fujii Kiyonaga , Kondo Fumio , Park Ho‐dong , Watanabe Mariyo F.
Published: August 2002

The relationship between Microcystis composition and the production of microcystins and nontoxic peptides in bloom cells, which was regularly collected in Lake Suwa, Japan, in the summer season from 1991 to 1994, was investigated. In order to determine the structures of the nontoxic peptides, we collected large amounts of bloom materials from the same lake on July 23, 1991, and isolated three nontoxic peptides. They were named as aeruginopeptins 917S‐A, ‐B, and ‐C, and their structures were mainly determined by a mass spectrometry/mass spectrometry (MS/MS) technique as 19‐membered cyclic depsipeptides possessing the Ahp (3‐amino‐6‐hydroxy‐2‐piperidone) moiety. An analysis of the microcystins and aeruginopeptins in the collected bloom cells and their Microcystis composition suggested that the M. aeruginosa large cell size produces both microcystins and aeruginopeptins, and the production of both compounds is genetically closely related. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 298–305, 2001
Differential space–time modulation for DS‐CDMA systems
Authors: Liu Jianhua , Li Jian
Published: August 2002

Differential space–time modulation (DSTM) schemes were recently proposed to fully exploit the transmit and receive antenna diversities without the need for channel state information. DSTM is attractive in fast flat fading channels since accurate channel estimation is difficult to achieve. In this paper, we propose a new modulation scheme to improve the performance of DS‐CDMA systems in fast time‐dispersive fading channels. This scheme is referred to as the differential space–time modulation for DS‐CDMA (DST‐CDMA) systems. The new modulation and demodulation schemes are especially studied for the fast fading down‐link transmission in DS‐CDMA systems employing multiple transmit antennas and one receive antenna. We present three demodulation schemes, referred to as the differential space–time Rake (DSTR) receiver, differential space–time deterministic (DSTD) receiver, and differential space–time deterministic de‐prefix (DSTDD) receiver, respectively. The DSTD receiver exploits the known information of the spreading sequences and their delayed paths deterministically besides the Rake‐type combination; consequently, it can outperform the DSTR receiver, which employs the Rake‐type combination only, especially for moderate‐to‐high SNR. The DSTDD receiver avoids the effect of intersymbol interference and hence can offer better performance than the DSTD receiver. Copyright © 2001 John Wiley & Sons, Ltd.
Total reflection by synchrotron radiation: trace determination in nuclear materials
Authors: Simabuco S. M. , Vázquez C. , Boeykens S. , Barroso R. C.
Published: August 2002

The chemical control of impurities in nuclear materials is indispensable in order to ensure efficient operation of the reactors. The maximum concentration admitted depends on the elements and in most cases is in the parts per billion range. Conventional analytical methods require a preconcentration treatment of the sample and a previous separation of the matrix (uranium). In this work, we investigated the use of total reflection x‐ray fluorescence with synchrotron radiation excitation as an alternative methodology for the determination of impurities in nuclear materials, namely K, Ca, Ti, Cr, Mn, Fe, Ni, Cu and As. The detection limits obtained were in the range 0.1–20 ng ml−1 for a 1000 s counting time. Copyright © 2002 John Wiley & Sons, Ltd.
Disruption and phenotypic analysis of six open reading frames from chromosome VII of Saccharomyces cerevisiae reveals one essential gene
Authors: Guerreiro Paulo , Rodrigues‐Pousada Claudina
Published: August 2002

Six open reading frames (ORFs) located on chromosome VII of Saccharomyces cerevisiae (YGR205w, YGR210c, YGR211w, YGR241c, YGR243w and YGR244c) were disrupted in two different genetic backgrounds using short‐flanking homology (SFH) gene replacement. Sporulation and tetrad analysis showed that YGR211w, recently identified as the yeast ZPR1 gene, is an essential gene. The other five genes are non‐essential, and no phenotypes could be associated to their inactivation. Two of these genes have recently been further characterized: YGR241c (YAP1802) encodes a yeast adaptor protein and YGR244c (LSC2) encodes the β‐subunit of the succinyl‐CoA ligase. For each ORF, a replacement cassette with long flanking regions homologous to the target locus was cloned in pUG7, and the cognate wild‐type gene was cloned in pRS416. Copyright © 2001 John Wiley & Sons, Ltd.
Saccharomyces cerevisiae YCRO17c/CWH43 encodes a putative sensor/transporter protein upstream of the BCK2 branch of the PKC1‐dependent cell wall integrity pathway
Authors: Martin‐Yken Helene , Dagkessamanskaia Adilia , De Groot Piet , Ram Arthur , Klis Frans , François Jean
Published: August 2002

The Saccharomyces cerevisiae cwh43‐2 mutant, originally isolated for its Calcofluor white hypersensitivity, displays several cell wall defects similar to mutants in the PKC1–MPK1 pathway, including a growth defect and increased release of β‐1,6‐glucan and β‐glucosylated proteins into the growth medium at increased temperatures. The cloning of CWH43 showed that it corresponds to YCR017c and encodes a protein with 14–16 transmembrane segments containing several putative phosphorylation and glycosylation sites. The N‐terminal part of the amino acid sequence of Cwh43p shows 40% similarity with the mammalian FRAG1, a membrane protein that activates the fibroblast growth factor receptor of rat osteosarcoma (FGFR2‐ROS) and with protein sequences of four uncharacterized ORFs from Caenorhabditis elegans and one from Drosophila melanogaster. The C‐terminus of Cwh43p shows low similarities with a xylose permease of Bacillus megaterium and with putative sugar transporter from D. melanogaster, and has 52% similarity with a protein sequence from a Schizosaccharomyces pombe cDNA. A Cwh43–GFP fusion protein suggested a plasma membrane localization, although localization to the internal structure of the cells could not be excluded, and it concentrates to the bud tip of small budded cells and to the neck of dividing cells. Deletion of CWH43 resulted in cell wall defects less pronounced than those of the cwh43‐2 mutant. This allele‐specific phenotype appears to be due to a G–R substitution at position 57 in a highly conserved region of the protein. Genetic analysis places CWH43 upstream of the BCK2 branch of the PKC1 signalling pathway, since cwh43 mutations were synthetic lethal with pkc1 deletion, whereas the cwh43 defects could be rescued by overexpression of BCK2 and not by high‐copy‐number expression of genes encoding downstream proteins of the PKC1 pathway However, unlike BCK2, whose disruption in a cln3 mutant resulted in growth arrest in G1, no growth defect was observed in a double cwh43 cln3 mutants. Taken together, it is proposed that CWH43 encodes a protein with putative sensor and transporter domains acting in parallel to the main PKC1‐dependent cell wall integrity pathway, and that this gene has evolved into two distinct genes in higher eukaryotes. Copyright © 2001 John Wiley & Sons, Ltd.
The KlCYC1 gene, a downstream region for two differentially regulated transcripts
Authors: Angeles Freire‐Picos M. , Lombardía‐Ferreira Luís J. , Ramil Elvira , González‐Domínguez Mónica , Esperanza Cerdán M.
Published: August 2002

KlCYC1 encodes for cytochrome c in the yeast Kluyveromyces lactis and is transcribed in two mRNAs with different 3′‐processing points. This is an uncommon transcription mechanism in yeast mRNAs. The 3′ sequence encompassing the whole region that is needed to produce both mRNAs is analysed. We have determined identical processing points in K.lactis and in Saccharomyces cerevisiae cells transformed with KlCYC1; positions 698 and 1092 (with respect to the TAA) are the major polyadenylation points. This shows that the cis‐elements present in the KlCYC1 3′‐untranslated region (3′‐UTR) direct a processing mechanism that has been conserved in yeast. In K. lactis there is a high predominance of the shorter transcript (1.14 kb) only at the initial logarithmic growth phase. Interestingly, this growth phase‐dependent regulation of 3′‐UTR processing is lost when the gene is expressed in S. cerevisiae. Copyright © 2001 John Wiley & Sons, Ltd.
Genetic analysis of the karyotype instability in natural wine yeast strains
Authors: Carro David , Piña Benjamin
Published: August 2002

Yeast strains isolated from the wild may show high rates of changes in their karyotypes during vegetative growth. We analysed over 500 karyotypes from mitotic and meiotic derivatives of strain DC5, which has a chromosome rearrangement rate of 8.2×10−3 changes/generation. About 70% of the meiotic derivatives of DC5 had low rearrangement rates, with an average of 5.8×10−4 changes/generation, suggesting that karyotype instability behaved as a dominant phenotype. Diploid derivatives with low karyotype variability in mitosis also had low rates of chromosomal rearrangement during meiosis, suggesting that the two phenotypes may be linked. DC5 and some of its meiotic derivatives (both with high and low karyotype variability) had chromosome XII hypervariable bands. Their distribution among the meiotic products indicates that they are not indicators for genetic instability. To our knowledge, data in this paper are the first to indicate that karyotypically unstable yeast strains may give stable progeny at high rates. Understanding of the relevant mechanism(s) may allow the design of genetic strategies to stabilize karyotypes from natural and/or industrial wine yeasts with unacceptable karyotype rearrangement rates. Copyright © 2001 John Wiley & Sons, Ltd.
ZRC – A Refinement Calculus for Z
Authors: Cavalcanti Ana , Woodcock Jim
Published: August 2002

The fact that Z is a specification language only, with no associated program development method, is a widely recognised problem. As an answer to that, we present ZRC, a refinement calculus based on Morgan's work that incorporates the Z notation and follows its style and conventions. This work builds upon existing refinement techniques for Z, but distinguishes itself mainly in that ZRC is completely formalised. In this paper, we explain how programs can be derived from Z specifications using ZRC. We present ZRC-L, the language of our calculus, and its conversion laws, which are concerned with the transformation of Z schemas into programs of this language. Moreover, we present the weakest precondition semantics of ZRC-L, which is the basis for the derivation of the laws of ZRC. More than a refinement calculus, ZRC is a theory of refinement for Z.
Formal Performance Modelling and Evaluation of an Adaptive Mechanism for Packetised Audio over the Internet
Authors: Bernardo Marco , Gorrieri Roberto , Roccetti Marco
Published: August 2002

A case study is presented which concerns the design of an adaptive mechanism for packetised audio for use over the Internet. During the design process, the audio mechanism was modelled with the stochastically timed process algebra EMPA and analysed via simulation by the EMPA based software tool TwoTowers in order to predict the percentage of packets that are received in time for being played out. The predicted performance figures obtained from the algebraic model illustrated in advance the adequacy of the approach adopted in the design of the audio playout delay control mechanism. Based on these performance figures, it was possible to implement and develop the complete mechanism without incurring additional costs due to the late discovery of unexpected errors or inefficiency. Performance results obtained from experiments conducted on the field confirmed the predictive simulative results.
The Changing Face of Standardization: A Place for Formal Methods?
Authors: Duce David , Duke David , Faconti Giorgio , Herman Ivan
Published: August 2002

Many of the reported experiences in the industrial use of formal methods concern the development of products or product families, where the utility of the method is linked to direct savings in development costs or improved assurance of quality. However, one other area in which formal description techniques make a valuable contribution is in the development and documentation of International Standards, where the cost of using formal methods can be paid off both through increased quality of products that implement a given standard, and through the improved inter-operability of different implementations that comes from having a precise definition of the expected behaviour of a conforming implementation. Standards development, however, has some significant differences from product development, and comes with specific needs and constraints that affect the use of formal description techniques. This paper describes the role that formal methods played in the development of a new standard for distributed multimedia presentation. It describes a number of issues that arose from this experience, and which have longer term importance for formal methods in standards, particularly given the changes that are taking place in the way that standards are developed.
The Least Conjunctive Refinement and Promotion in the Refinement Calculus
Authors: Mahony Brendan P.
Published: August 2002

A syntactic calculation of Morgan's least conjunctive refinement operator for predicate transformers is developed. The operator is used to develop a general approach to lifting relational operators to predicate transformer operators. Predicate transformer versions of the relational conjunction and disjunction operators are considered in detail. The Z-based technique of program promotion is considered in a refinement calculus setting. A standard Z promotion example is recast in the refinement calculus.