bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding teachers′ receptivity to system‐wide educational
change
Authors: Waugh Russell , Godfrey John
Published: July 2002

Reports the results of a qualitative, cross‐sectional study
involving a survey of 549 teachers′ perceptions of the Unit Curriculum
system in 22 metropolitan state senior high schools in Perth, Western
Australia, in the context of system‐wide change, within a centralized
educational system. Surveyed perceptions of six general variables
applied to the specific case of the Unit Curriculum system. These
variables are: perceived cost benefit to the teacher; perceived
practicality in the classroom; alleviation of fears and concerns;
participation in school decisions on aspects affecting the classrooms;
perceived support from senior staff; and feelings towards the previous
system compared to the new system. Suggests these variables offer
pointers to educational administrators on how best to tailor system‐wide
changes so that teachers will be more receptive to the changes in the
implementation stage.
Explaining variation in teachers’ perceptions of principals’ leadership: a replication
Authors: Leithwood Kenneth , Jantzi Doris
Published: July 2002

What factors influence teachers to attribute leadership qualities to some principals and not others? In particular, what accounts for attributions of transformational school leadership? Guided by an information processing perspective to explain teachers’ attributions, answers to these questions were explored through data provided by an achieved sample of 1,253 elementary and secondary teachers from a single large school system. Replicating the framework and design of an earlier study by the same authors, this, as well as the previous study, found that teachers’ leadership attributions were largely explained by alterable rather than unalterable variables.
Stability of solutions of the overdetermined inverse heat conduction problems when discretized with respect to time
Authors: Maciag Artur , Jehad Al‐Khatib Mohammed
Published: July 2002

The inverse heat conduction problem with many internal responses is considered. After discretization with respect to time, the problem is described by a system of the Helmholtz equations in a recurrent form. An approximate solution of a heat conduction problem in an integral form is shown. Then, an approximate solution of an inverse heat conduction problem in a flat slab is presented for many internal temperature responses. Stability of the solution with respect to the internal response errors is investigated for two cases: when the integrals are calculated with the use of the average value theorem and when they are calculated numerically. Analysis of the norm of a matrix that is essential for the solution stability shows that in the case of three sensors the norm slightly changes with change of the middle sensor location. If more than three sensors are taken into consideration, the results practically will not change comparing to the case of three sensors. The internal temperature response errors are suppressed if the time step is greater than a certain critical value.
Bifurcation to oscillatory flow of the natural convection around a vertical channel in rectangular enclosure
Authors: Liu J.P. , Tao W.Q.
Published: July 2002

Numerical computations were performed for the heat transfer and fluid flow characteristics of natural convection with an internal vertical channel composed by a pair of parallel plates in a rectangular enclosure. The inner plates and the bounding wall of the enclosure were maintained at uniform but different temperatures. The plates were symmetrically arranged. Unsteady computation was performed to simulate the evolution process of the natural convection developing from the zero initial field. The cases of Ra = 2 × 104, 2 × 105 and 106 were studied. A symmetrical steady solution was achieved for the case of Ra = 2 × 104. For Ra = 2 × 105 and 106, time dependent asymmetrical processes were observed. The flow oscillating process seemed to be more complex at Ra = 2 × 105 than that at Ra = 106, which is quasi‐periodic with two frequencies.
Participant observation of a minor train crash
Authors: McCollin Chris
Published: July 2002

A two‐carriage train crash with a container lorry resulted in minor injuries to various people on board. A description of the event history of the incident including the types of injury and the reaction to shock are described. Corrective actions are discussed including guidelines for treatment to victims of shock, railway staff training in the event of an emergency, an event database and an egress ladder installed into carriage doors. Comparison is made to similar events and their corresponding recommendations, which suggests that a directory of incidents should be set up and maintained so that unambiguous corrective actions can be addressed.
A critical review of the business excellence quality model applied to further education colleges
Authors: McAdam Rodney , Welsh William
Published: July 2002

In April 1998, the legal status of further education colleges in Northern Ireland changed (Further Education (Northern Ireland) Order 1997). Their new legal status offers colleges the opportunity to develop a greater business focus while preserving a robust framework of public accountability. Colleges will need to respond in a balanced fashion to the competing demands made by multiple stakeholders. In order to assist colleges to respond to these challenges, the Department of Education (NI) has commissioned the Business Development Service, an agency within the Department of Finance and Personnel, to provide consultancy to those colleges which wish to explore the use of the business excellence quality model (developed by the European Foundation for Quality Management 1988‐1991). This paper evaluates the relevance and validity of this approach for all 17 further education colleges in Northern Ireland.
Quality for Some? What about the Rest
Authors: Race Phil
Published: July 2002

Takes a sharp look at the nature of assessment, and in particular at all
the people that become excluded from education provision because they do
not happen to be skilled at delivering those qualities measured by
assessment systems and instruments in common usage. Suggests that
success in assessment often depends on people′s ability to write
examination answers, whereas the real product of education should be
people with far more diverse skills than this. Concludes with a set of
recommendations and questions to consider in developing the quality of
assessment.
Academic quality in TQM: issues in teaching and learning
Authors: Chadwick Priscilla
Published: July 2002

TQM in higher education, as in other professions, is a commitment
to continuous improvement. Explores issues involved in enhancing the
quality of teaching and learning in higher education. In 1992 the
Postgraduate Certificate in Higher Education was introduced to accredit
formally the work done by new lecturers. The course included survival
teaching skills, assessment, course design, equal opportunities issues,
information technology and multimedia. The course proved popular and
more than half of the newly‐appointed staff continued into the second
year. Supported by trained mentors, they became increasingly confident
in sharing good practice with academic colleagues; staff development
within schools was enhanced. Developments in information technology,
resource‐based learning and student learning support have further
improved the quality of teaching and learning.
Context specificity and quality continuing professional education.
Part 2: towards a meaningful approach
Authors: Tovey Philip
Published: July 2002

The second of two related articles examining quality assurance in
university continuing professional education (CPE). Proposes an action
framework which is the outcome of research comprising three elements:
postal questionnaires which examined the attitudes, aims and practices
of specialist and non‐specialist providers of university CPE; an
analytical review of practice in other branches of education, and in
health, welfare and construction, including BS 5750; and case study
research conducted with professional bodies and employers. Argues that a
context‐specific approach to quality is required, which would remove
both the market and the customer as determinant concepts and would,
instead, concentrate on developing quality to fit the character of a
distinct and complex educational practice.
Mass higher education: a first stage model for the United Kingdom
Authors: Harvey Roger C. , Ashworth Allan
Published: July 2002

By the year 2000 it is planned that the participation rate in
higher education in the United Kingdom will be 32 per cent, yet there
has been no meaningful debate on how this can be achieved in an
affordable way. It is expected that the present level of resourcing for
higher education is insufficient to achieve the expansion required
without change to the traditional operating characteristics of the
system. Proposes adjustments to the existing system to ensure that the
planned expansion can be achieved while maintaining an appropriate level
of quality. The effectiveness of the proposed system is based on:
opportunities offered to the population measured by the level of
participation; the attainment measured by what is learned and the added
value achieved; and the value for money measured by the unit costs.
Financial projections indicate that reductions in unit costs can be
achieved. The overall increase in total costs of 16 per cent between
1992 and the year 2000 is not judged to involve a significant increase
in the UK′s commitment of 1.1 per cent of the gross domestic product
spent on higher education.
Validation of professional degrees: the micropolitical climate and ethical dilemmas
Authors: Hammick Marilyn
Published: July 2002

The system of validating degrees awarded by British universities is a process of peer review. This now applies to professional health‐care degrees which also confer eligibility for state registration. The context of these validations is the new environment of market‐led education, and the fate of valuable contracts may depend on the decision of the validation committee. Explores the micro‐politics of such validation events which involve representatives from professional organizations and university staff. The focus is on the power relationships within the validation committee and the influences on the final decision. The work is based on experiential and documentary evidence.
The academic quality audit of an Asian postgraduate university
Authors: Connelly Michael
Published: July 2002

Considers the question of how an Asian postgraduate institution sets up an academic quality assurance process when it is geographically remote from universities that are similar and has a cultural context that is unique in some respects. Presents a short case study of the development of a combined vertical and horizontal internal quality audit which combines both an institutional and individual survey into an ongoing process of quality enhancement.
Developing a dynamic in a learning innovation
Authors: Roffe Ian
Published: July 2002

Examines the practical and theoretical issues involved in starting and sustaining an innovatory learning programme by analysing the case of screen translation. Considers the strategic development of programmes as well as student groups, and discusses the managerial needs and continuous quality improvement involved in maintaining a dynamic to the learning innovation. Finally, proposes an adapted curriculum development model to include the managerial impetus required to maintain innovative momentum.
What’s your problem? Giving more than lip‐service to learning support
Authors: Carroll Donal
Published: July 2002

Suggests a particular practice should be developed when dealing with difficult adult learners. This involves changing the purpose of conventional “tutorials” to “learning clinics”. These would be one‐to‐one, in order to diagnose learning needs, and embed a learning culture designed to develop critical, independent learners. Critical practice in this forum is suggested through evaluating a number of verbatim learner/teacher exchanges including role and behaviour of teacher, use and purpose of language used, and how decisions are made. Suggests a critical framework based on adult learning theories. Includes particularly, the role of experience, as potential barrier as well as resource.
Understanding standards‐based quality assurance: part I ‐ rationale and conceptual basis
Authors: Jackson Norman
Published: July 2002

Examines the reasons for the strategic move in UK higher education to a new national quality assurance regime that is primarily focused on academic standards. Considers the conceptual basis on which the new approach is founded as a precursor to examining the proposals made by the National Committee of Inquiry in Higher Education and the initial development work undertaken by the Quality Assurance Agency to create a policy framework.
Assessing the assessors: a comparative study
Authors: Stensaker Bjørn
Published: July 2002

In a national quality assessment of business administration in Norway, the work of eight simultaneously working external assessment panels was studied. The article examines how the panels considered different kinds of information sources and processes during the assessment, and in writing their reports. The study shows that information from self‐evaluation reports and instructional checklists, from an arranged conference and a training seminar, was ranked low by the panels, while information from the interaction between the panels and the assessed department and/or institution was highly valued together with internal discussions inside the panels and the assessors’ own knowledge and experience. In writing their external reports, the information highly valued was used most by the assessors. Possible implications of the study, especially in relation to the organisation and set‐up of external assessments, are presented in the conclusion.
Understanding standards‐based quality assurance: part II ‐ nuts and bolts of the “Dearing“ policy framework
Authors: Jackson Norman
Published: July 2002

Examines the proposals made by the National Committee of Inquiry in Higher Education (Dearing Report) for a national quality assurance regime that is focused on academic standards. Provides a simple conceptual aid to explain relationships between the elements of the policy framework. Considers the methodologies that are being developed by the Quality Assurance Agency and the implications for institutional and academic practice. Identifies factors and issues that will need to be considered during policy development.
Improving teaching in British higher education
Authors: Badley Graham
Published: July 2002

Outlines a series of initiatives at both national and institutional levels which suggest that British higher education is becoming more serious about improving the quality of university teaching. National initiatives include the Teaching Quality Assessment exercise, the Teaching and Learning Technology Programme and the Fund for the Development of Teaching and Learning. The establishment of the Institute for Learning and Teaching in Higher Education is also briefly highlighted. At the institutional level initiatives include the creation of more effective units or centres to promote learning and teaching, many of which intend to offer teacher development programmes accredited by the new Institute for Learning and Teaching. Such units also provide a valuable range of workshops, consultancy and project support in order to help universities improve their understanding of the practice and the theory of teaching in higher education. Many such units also promote research, especially action research, into university teaching and learning.
Generic level learning outcome templates: a tool for benchmarking student achievement levels throughout a university
Authors: Ellington Henry
Published: July 2002

Shows how Scotland’s Robert Gordon University is currently attempting to address the recommendations of the Dearing Report in respect of detailed programme specifications, and of the Partington Report regarding benchmarking of levels of student achievement, in the course of implementing a university‐wide course modularisation programme. Describes how the university has developed a set of generic level learning outcome templates which specify the levels that students should attain in the four areas identified by Dearing (knowledge and understanding; key skills; cognitive skills; and subject‐specific skills) at the various stages of undergraduate and taught‐postgraduate courses. Explains how course teams are using these generic templates to produce “contextualised” versions for their own courses, and are then using the resulting contextualised level learning outcomes as benchmarking guidelines when writing the individual module descriptors for these courses. Describes how this work is being facilitated throughout the university.
Investors in People in further and higher education: the critical issues
Authors: Quayle Michael , Murphy John
Published: July 2002

The initial enthusiasm for further and higher education institutions to achieve the Investors in People (IiP) award appears to have faded. The reasons for this are many, and varied, and this paper examines the critical issues being encountered. It considers the need for strategic development and effectiveness, and suggests a new management paradigm is necessary if IiP accreditation is to be achieved.
Shielding your company against information compromise
Authors: Helms Marilyn M. , Ettkin Lawrence P. , Morris Daniel J.
Published: July 2002

With the growth of information technologies and with more firms partnering, a major concern for organizations today is the protection of competitive information from thieving. Firms must develop an understanding of the multidimensional flavor of defensive intelligence and its challenges in a bureaucracy, examine companies’ vulnerabilities and implement some basic defensive intelligence measures in order to protect their organization’s knowledge. Organizations must address major areas of vulnerabilities, including employees, partners and public information. Firms can take specific actions to minimize successful acts of espionage such as protections preventing unauthorized use of information systems. Companies should develop a set of priorities and determine where and to what degree security procedures need to be implemented. Beyond security, employing proactive measures can provide a valuable weapon for the long‐term prosperity of your firm.
Protecting availability in complex computer environments
Authors: Gubbins Barry
Published: July 2002

As online business dependencies continue to rise and at the same
time tend to rely on more and more complex environments, the risk of
computer service interruption, i.e. disruption rather than disaster,
having a major effect on business rises dramatically. To combat this
risk, products are emerging to automate the management of such demanding
environments. This automation includes the use of management alerts,
cross‐platform administration and centralized performance monitoring.
Describes one such management system. Briefly gives an account of the
system′s components, domains and technologies.
Commercialization of cryptography
Authors: Liddy Carrie
Published: July 2002

Presents the major approaches for achieving commercial security on the Internet, public key and key escrow. Discusses the implications of (US) legislation putting limitations on the type or strength of key it is best to employ for a given business. Presents the typical modes of delivering authentication and other services.
The evolution of information technology
Authors: Mutsaers Ernest‐Jan , van der Zee Han , Giertz Henrik
Published: July 2002

The first version of the Nolan Stages Theory appeared in 1973. It explained the dynamics of the increasingly vital production factor called IT. This theory is probably the most well‐known and most widespread framework of the development of information technology in organisations. It provides many insights in the ways in which IT has evolved and continues to evolve. Moreover, it offers both senior (business) management and IT management the possibility of directing this complex phenomenon, without immediately going into technical details. Since 1973, a number of associated articles have been published by Richard L. Nolan and a number of co‐authors. The theory has continuously been adapted to the current IT environment and has been applied by a huge number of large companies throughout the world. Proceeds with the development of the Stages Theory in order to be able to deal with the business and IT issues of the next five to ten years.
Internet security: a case study of firewall selection
Authors: Wen H. Joseph , Tarn Jyh‐Horng Michael
Published: July 2002

The Internet itself was not designed with security in mind. It was originally designed for research purposes, with open access to willing and able participants. Only recently, with the influx of thousands, if not millions, of users, have the stakes been raised and very serious security concerns brought to light. Following an overview of the threats of Internet‐based electronic commerce, this paper discusses two Internet firewall architectures and seven Internet access control technologies. A case study of how a small company, SunCom Int’l Corporation (SIC), selected its Internet firewall is presented. Finally, this paper concludes with a summary and the future of the Internet firewall.
Achieving IT success
Authors: Brockway Douglas , Hurley Margaret
Published: July 2002

Postulates that there are identifiable and measurable criteria for achieving success in the management of information technology and discusses these criteria. Presents hypotheses regarding the links between business success and IT success. Presents results of research among US‐based senior IT management testing the hypotheses. Concludes that business success drives or leads IT success and that IT must align its aspirations and actions to the business. Prescribes an action plan for senior IT management.
The evolution of certificate model architecture
Authors: Liddy Carrie , Sturgeon Alice
Published: July 2002

Many products and enterprise solutions are becoming available to ensure seamless, secured electronic transactions, all of which must find common trust. This paper reviews the models along a continuum with the low‐assurance self‐signing certificate authority (CA) at one end, and the high‐assurance PKI hierarchical CA at the other. The evolution of technologies and market readiness along the continuum is discussed. The authors expand on earlier discussions of technology and geopolitical solutions and suggest mechanisms, principally the adoption of international standards and protocols, to establish universal trust across national boundaries.
Identifying the proceeds of electronic money fraud
Authors: Kreltszheim David
Published: July 2002

eCash by DigiCash is one of a range of software‐based systems devised for payments to be made over the Internet by the use of electronic tokens or “coins” (known colloquially as “electronic money”). As in the case of other new electronic systems, the functioning of the system gives rise to novel and difficult legal issues, some of which have yet to be resolved. This article will consider the extent to which a user of the system whose value is stolen may use the common law and equitable tracing rules as a means of taking action against the perpetrator of the fraud.
The status of library professionals in academic institutions of Orissa
Authors: Parida Baman
Published: July 2002

This study is based on a survey of library personnel working in different academic libraries in Orissa. It determines the type of status these library professionals prefer, the criteria for evaluating their performance for promotion and salary, whether they prefer to be evaluated like teachers, and the input of faculty members in library matters. The study shows that 80 per cent of the professionals interviewed preferred academic status rather than faculty status. This means they prefer to establish their own ranking system rather than be equated with teachers. All university librarians, however, prefer to be assessed for promotion through an expert selection committee, as is the case for teachers.
Deploying networked CD‐ROM services in a research institute: a case study
Authors: Kumar Satish
Published: July 2002

Describes the advantages of CD‐ROM networking. Discusses the different networking models available for deploying networked CD‐ROM services. States the set of specifications selected to implement the networked CD‐ROM services in Tata Energy Research Institute and the approach taken to meet these. Also lists the CD‐ROM titles made available through the networked CD‐ROM services.
Recognising deductive processes in qualitative research
Authors: Hyde Kenneth F.
Published: July 2002

States that there are two general approaches to reasoning which may result in the acquisition of new knowledge: inductive reasoning commences with observation of specific instances, and seeks to establish generalisations; deductive reasoning commences with generalisations, and seeks to see if these generalisations apply to specific instances. Most often, qualitative research follows an inductive process. In most instances, however, theory developed from qualitative investigation is untested theory. Both quantitative and qualitative researchers demonstrate deductive and inductive processes in their research, but fail to recognise these processes. The research paradigm followed in this article is a post‐positivist (“realist”) one. This is not incompatible with the use of qualitative research methods. Argues that the adoption of formal deductive procedures can represent an important step for assuring conviction in qualitative research findings. Discusses how, and under what circumstances, qualitative researchers might adopt formal deductive procedures in their research. One approach, theory testing by “pattern matching”, is illustrated with a sample application.
Solution structure and backbone dynamics of an ω‐conotoxin precursor
Authors: Goldenberg David P. , Koehn Rachel E. , Gilbert Dara E. , Wagner Gerhard
Published: July 2002

Nuclear magnetic resonance spectroscopy was used to characterize the solution structure and backbone dynamics of a putative precursor form of ω‐conotoxin MVIIA, a 25‐amino‐acid residue peptide antagonist of voltage‐gated Ca2+ channels. The mature peptide is found in the venom of a fish‐hunting marine snail Conus magus and contains an amidated carboxyl terminus that is generated by oxidative cleavage of a Gly residue. The form examined in this study is identical to the mature peptide except for the presence of the unmodified carboxy‐terminal Gly. This form, referred to as ω‐MVIIA–Gly, has previously been shown to refold and form its disulfides more efficiently than the mature form, suggesting that the presence of the terminal Gly may favor folding in vivo. The nuclear magnetic resonance (NMR) structure determination indicated that the fold of ω‐MVIIA–Gly is very similar to that previously determined for the mature form, but revealed that the terminal Gly residue participates in a network of hydrogen bonds involving both backbone and side chain atoms, very likely accounting for the enhanced stability and folding efficiency. 15N relaxation experiments indicated that the backbone is well ordered on the nanosecond time scale but that residues 9–15 undergo a conformational exchange processes with a time constant of ∼35 microseconds. Other studies have implicated this segment in the binding of the peptide to its physiological target, and the observed motions may play a role in allowing the peptide to enter the binding site
Role of water in the catalytic cycle of E. coli dihydrofolate reductase
Authors: Shrimpton Paul , Allemann Rudolf K.
Published: July 2002

Dihydrofolate reductase (DHFR) catalyzes the nicotinamide adenine dinucleotide phosphate (NADPH)‐dependent reduction of 7,8‐dihydrofolate (H2F) to 5,6,7,8‐tetrahydrofolate (H4F). Because of the absence of any ionizable group in the vicinity of N5 of dihydrofolate it has been proposed that N5 could be protonated directly by a water molecule at the active site in the ternary complex of the Escherichia coli enzyme with cofactor and substrate. However, in the X‐ray structures representing the Michaelis complex of the E. coli enzyme, a water molecule has never been observed in a position that could allow protonation of N5. In fact, the side chain of Met 20 blocks access to N5. Energy minimization reported here revealed that water could be placed in hydrogen bonding distance of N5 with only minor conformational changes. The r.m.s. deviation between the conformation of the M20 loop observed in the crystal structures of the ternary complexes and the conformation adopted after energy minimization was only 0.79 Å. We performed molecular dynamics simulations to determine the accessibility by water of the active site of the Michaelis complex of DHFR. Water could access N5 relatively freely after an equilibration time of approximately 300 psec during which the side chain of Met 20 blocked water access. Protonation of N5 did not increase the accessibility by water. Surprisingly the number of near‐attack conformations, in which the distance between the pro‐R hydrogen of NADPH and C6 of dihydrofolate was less than 3.5 Å and the angle between C4 and the pro‐R hydrogen of NADPH and C6 of dihydrofolate was greater than 120 degrees, did not increase after protonation. However, when the hydride was transferred from NADPH to C6 of dihydrofolate before protonation, the side chain of Met 20 moved away from N5 after approximately 100 psec thereby providing water access. The average time during which water was found in hydrogen bonding distance to N5 was significantly increased. These results suggest that hydride transfer might occur early to midway through the reaction followed by protonation. Such a mechanism is supported by the very close contact between C4 of NADP+ and C6 of folate observed in the crystal structures of the ternary enzyme complexes, when the M20 loop is in its closed conformation.
Chloride transport in microperfused interlobular ducts isolated from guinea‐pig pancreas
Authors: Ishiguro H. , Naruse S. , Kitagawa M. , Mabuchi T. , Kondo T. , Hayakawa T. , Case R. M. , Steward M. C.
Published: July 2002

Isolated interlobular ducts from the guinea‐pig pancreas secrete a HCO3−‐rich fluid in response to secretin. To determine the role of Cl− transporters in this process, intracellular Cl− concentration ([Cl−]i) was measured in ducts loaded with the Cl−‐sensitive fluoroprobe, 6‐methoxy‐N‐ethylquinolinium chloride (MEQ). [Cl−]i decreased when the luminal Cl− concentration was reduced. This effect was stimulated by forskolin, was not dependent on HCO3− and was not inhibited by application of the anion channel/transporter inhibitor H2DIDS to the luminal membrane. It is therefore attributed to a cAMP‐stimulated Cl− conductance, probably the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. [Cl−]i also decreased when the basolateral Cl− concentration was reduced. This effect was not stimulated by forskolin, was largely dependent on HCO3− and was inhibited by basolateral H2DIDS. It is therefore mediated mainly by Cl−/HCO3− exchange. With high Cl− and low HCO3− concentrations in the lumen, steady‐state [Cl−]i was 25‐35 mm in unstimulated cells. Stimulation with forskolin caused [Cl−]i to increase by approximately 4 mm due to activation of the luminal anion exchanger. With low Cl− and high HCO3− concentrations in the lumen to simulate physiological conditions, steady‐state [Cl−]i was 10–15 mm in unstimulated cells. Upon stimulation with forskolin, [Cl−]i fell to approximately 7 mm due to increased Cl− efflux via the luminal conductance. We conclude that, during stimulation under physiological conditions, [Cl−]i decreases to very low levels in guinea‐pig pancreatic duct cells, largely as a result of the limited capacity of the basolateral transporters for Cl− uptake. The resulting lack of competition from intracellular Cl− may therefore favour HCO3− secretion via anion conductances in the luminal membrane, possibly CFTR.
Role of ATP decrease in secretion induced by mitochondrial dysfunction in guinea‐pig adrenal chromaffin cells
Authors: Inoue M. , Fujishiro N. , Imanaga I. , Sakamoto Y.
Published: July 2002

The mechanism related to mitochondrial dysfunction‐induced catecholamine (CA) secretion in dispersed guinea‐pig adrenal chromaffin cells was investigated using amperometry and confocal laser microscopy. Application of CCCP, which does not stimulate generation of reactive oxygen species (ROS), reversibly induced CA secretion, whereas application of either cyanide or oligomycin (OL), a stimulator for ROS, enhanced CA secretion to a smaller extent. The CCCP‐induced secretion was abolished by removal of external Ca2+ ions and was markedly diminished by D600. The mitochondrial membrane potential, measured using rhodamine 123, was rapidly lost in response to CCCP, but did not change noticeably during a 3 min exposure to OL. Prior exposure to OL markedly facilitated depolarization of the mitochondrial membrane potential in response to cyanide. The mitochondrial inhibitors rapidly produced an increase in Magnesium Green (MgG) fluorescence in the absence of external Ca2+ and Mg2+ ions, an increase that was larger in the cytoplasm than in the nucleus. The rank order of potency in increasing MgG fluorescence among the inhibitors was similar to that in increasing secretion. Thus, mitochondrial inhibition rapidly decreases [ATP] and the mitochondrial dysfunction‐induced secretion is not due to ROS generation or to mitochondrial depolarization, but is possibly mediated by a decrease in ATP.
Role of the medullary raphé in thermoregulatory vasomotor control in rats
Authors: Tanaka Mutsumi , Nagashima Kei , McAllen Robin M. , Kanosue Kazuyuki
Published: July 2002

To investigate the involvement of the medullary raphé in thermoregulatory vasomotor control, we chemically manipulated raphé neuronal activity while monitoring the tail vasomotor response to preoptic warming. For comparison, neuronal activity in the rostral ventrolateral medulla (RVLM) was manipulated in similar experiments. Injections of d,l‐homocysteic acid (DLH; 0.5 mm, 0.3 μl) into a restricted region of the ventral medullary raphé suppressed the tail vasodilatation normally elicited by warming the preoptic area to 42 °C. DLH injection into the RVLM also suppressed the vasodilatation elicited by preoptic warming. Injection of bicuculline (0.5 mm, 0.3 μl) into the same raphé region suppressed the vasodilatation elicited by preoptic warming. Bicuculline injection into the RVLM did not suppress tail vasodilatation. These results suggest that neurones in both the medullary raphé and the RVLM are vasoconstrictor to the tail, but only those in the raphé receive inhibitory input from the preoptic area. That input might be direct and/or indirect (e.g. via the periaqueductal grey matter).
Gating, modulation and subunit composition of voltage‐gated K+ channels in dendritic inhibitory interneurones of rat hippocampus
Authors: Lien Cheng‐Chang , Martina Marco , Schultz Jobst H. , Ehmke Heimo , Jonas Peter
Published: July 2002

GABAergic interneurones are diverse in their morphological and functional properties. Perisomatic inhibitory cells show fast spiking during sustained current injection, whereas dendritic inhibitory cells fire action potentials with lower frequency. We examined functional and molecular properties of K+ channels in interneurones with horizontal dendrites in stratum oriens‐alveus (OA) of the hippocampal CA1 region, which mainly comprise somatostatin‐positive dendritic inhibitory cells. Voltage‐gated K+ currents in nucleated patches isolated from OA interneurones consisted of three major components: a fast delayed rectifier K+ current component that was highly sensitive to external 4‐aminopyridine (4‐AP) and tetraethylammonium (TEA) (half‐maximal inhibitory concentrations < 0.1 mm for both blockers), a slow delayed rectifier K+ current component that was sensitive to high concentrations of TEA, but insensitive to 4‐AP, and a rapidly inactivating A‐type K+ current component that was blocked by high concentrations of 4‐AP, but resistant to TEA. The relative contributions of these components to the macroscopic K+ current were estimated as 57 ± 5, 25 ± 6, and 19 ± 2 %, respectively. Dendrotoxin, a selective blocker of Kv1 channels had only minimal effects on K+ currents in nucleated patches. Coapplication of the membrane‐permeant cAMP analogue 8‐(4‐chlorophenylthio)‐adenosine 3′:5′‐cyclic monophosphate (cpt‐cAMP) and the phosphodiesterase blocker isobutyl‐methylxanthine (IBMX) resulted in a selective inhibition of the fast delayed rectifier K+ current component. This inhibition was absent in the presence of the protein kinase A (PKA) inhibitor H‐89, implying the involvement of PKA‐mediated phosphorylation. Single‐cell reverse transcription‐polymerase chain reaction (RT‐PCR) analysis revealed a high abundance of Kv3.2 mRNA in OA interneurones, whereas the expression level of Kv3.1 mRNA was markedly lower. Similarly, RT‐PCR analysis showed a high abundance of Kv4.3 mRNA, whereas Kv4.2 mRNA was undetectable. This suggests that the fast delayed rectifier K+ current and the A‐type K+ current component are mediated predominantly by homomeric Kv3.2 and Kv4.3 channels. Selective modulation of Kv3.2 channels in OA interneurones by cAMP is likely to be an important factor regulating the activity of dendritic inhibitory cells in principal neurone‐interneurone microcircuits.
Performance Analysis of Parallel Mechanism Architectures for CNC Machining Applications
Authors: Kim Jinwook , Park Changbeom , Kim Jongwon , Park F. C.
Published: July 2002

In this paper we propose a set of criteria to evaluate the performance of various parallel mechanism architectures for CNC machining applications. In the robotics literature mathematical formulations of qualities like manipulability, stiffness, and workspace volume have been proposed to evaluate the performance of general-purpose robots. Here we propose a set of performance measures that specifically address features of the machining process. We define precise notions of machine tool workspace, joint and link stiffness, and position and orientation manipulability. The performance of various existing 6 d.o.f. architectures are evaluated with these measures. The analytical methodology presented here, in combination with a graphics-based CAD software environment, can serve as a useful tool in the design of high-performance parallel mechanism machine tools. [S1087-1357(00)01804-9]
An Invariance Principle for Discontinuous Dynamic Systems With Application to a Coulomb Friction Oscillator
Authors: Alvarez Joaquin , Orlov Iouri , Acho Leonardo
Published: July 2002

An invariance principle for a class of ordinary differential equations with discontinuous right-hand side is developed. Based on this principle, asymptotic stability of one-degree-of-freedom mechanical oscillators with Coulomb friction is studied. The system is shown to be asymptotically stabilizable via a static feedback of the position, unlike those systems with no friction, whose stabilization requires a dynamic feedback when the position is the only available measurement. Along with this development, a velocity observer is proposed. Theoretical results of the paper are supported by some numerical simulations which, in addition, carry out a finite-time convergence of the controller and the observer proposed. [S0022-0434(00)00804-2]
Update on the Progress of the Brazilian Wood BIG-GT Demonstration Project
Authors: Waldheim L. , Carpentieri E.
Published: July 2002

Biomass integrated gasification-gas turbine (BIG-GT) technology offers the opportunity for efficient and environmentally sound power generation from biomass fuels. Since biomass is “carbon-neutral” it can be used in power generation equipment without contributing to the “greenhouse effect” if it is grown sustainably. The Brazilian BIG-GT initiative is one of a number of initiatives world-wide aimed at demonstrating, and thereby establishing, biomass as an energy resource for power production. The goal of the Brazilian BIG-GT project is to confirm the commercial viability of producing electricity from wood through the use of biomass-fueled integrated gasification combined-cycle (BIG-GT) technology. To fulfil this goal a 32 MWe eucalyptus-fueled demonstration power plant will be built in Brazil on the basis of a design made by TPS Termiska Processer AB (TPS). The first two phases of the project, which included experimental and engineering studies and the basic engineering of the plant, were completed in 1997. The next phase of the project, the construction and commissioning of the plant, is the recipient of a U.S. $35 million grant from the Global Environmental Facility (GEF) of the United Nations Development Program (UNDP), in addition to financing from the World Bank (WB). The plant will be built in Bahia, north-eastern Brazil. The customer of the plant is a consortium, SER—Sistemas de Energia Renova´vel, comprising of CHESF (Companhia Hidro Ele´trica do Sa˜o Francisco), a federally owned electricity generation and distribution company, Electrobras (Centrais Ele´tricas Brasileiras), a holding company comprising of the main Brazilian companies from the electric generation and distribution sector, and Shell Brasil. Start-up of the plant is scheduled for the year 2000. The plant will be based on a TPS designed atmospheric-pressure gasification/gas cleaning process. The product gas will be fired in a modified GE LM 2500 gas turbine. The gasification and gas cleaning process is based on the use of a circulating fluidized bed gasifier, secondary stage catalytic tar cracker and conventional cold filter and wet scrubbing technology. The feedstock to the plant will be mainly eucalyptus wood from a dedicated plantation which is harvested on a three-year cycle. This paper describes the background of the project leading up to the technology selection, the technology that will be employed in the plant and the outline of the economics of this “first-of-a-kind” plant. The progress made in establishing the organization and the formal framework (e.g., securing the electricity and fuel contracts) are also reported. Future projections of likely technological improvements and cost reductions, and their effect on the overall economics of an Nth plant, are presented.
Analysis of the Piston Ring/Liner Oil Film Development During Warm-Up for an SI-Engine
Authors: Froelund K. , Schramm J. , Tian T. , Wong V. , Hochgreb S.
Published: July 2002

A one-dimensional ring-pack lubrication model developed at MIT is applied to simulate the oil film behavior during the warm-up period of a Kohler spark ignition engine. This is done by making assumptions for the evolution of the oil temperatures during warm-up and that the oil control ring during downstrokes is fully flooded. The ring-pack lubrication model includes features such as three different lubrication regimes, i.e., pure hydrodynamic lubrication, boundary lubrication and pure asperity contact, nonsteady wetting of both inlet and outlet of the piston ring, capability to use all ring face profiles that can be approximated by piece-wise polynomials, and, finally, the ability to model the rheology of multigrade oils. Not surprisingly, the simulations show that by far the most important parameter is the temperature dependence of the oil viscosity.
Scratching Test of Hard-Brittle Materials Under High Hydrostatic Pressure
Authors: Yoshino Masahiko , Aoki Takayuki , Shirakashi Takahiro
Published: July 2002

This paper proposes machining under high hydrostatic pressure as a new damage-free machining method for hard-brittle materials. Experiments for this study utilized a specially designed scratching test device, and the pin-on-disc scratching tests were conducted with three (3) hard-brittle materials (i.e., silicon, glass, and quartz) under pressure of 400 MPa and zero MPa. Traces of scratches on these specimens were examined with microscopes to evaluate the effects of hydrostatic pressure on machining defects. The results of the experiments show that hydrostatic pressure is efficient in minimizing machining defects and optimizing the productivity of the hard-brittle materials used in these experiments. Based on these findings, the paper concludes that the origin of a machining crack must exist in the subsurface of the workmaterial.
Intersonic Crack Propagation—Part I: The Fundamental Solution
Authors: Huang Y. , Gao H.
Published: July 2002

Recent experiments of Rosakis et al. have clearly shown that the crack-tip velocity can exceed the shear wave speed for a crack tip propagating between two weakly bonded, identical and isotropic solids under shear-dominated loading. This has motivated recent theoretical and numerical studies on intersonic crack propagation. We have obtained analytically the fundamental solution for mode-II intersonic crack propagation in this paper. This fundamental solution can provide the general solutions for intersonic crack propagation under arbitrarily initial equilibrium fields. We have also developed a cohesive zone model to determine the crack-tip energy release for an intersonic shear crack.
An Analytical Solution for Incompressible Flow Through Parallel Multiple Jets
Authors: Wang Junye , Priestman Geoffrey H. , Wu Dongdi
Published: July 2002

A theoretical model of multiple jet flow is introduced based on the thin shear layer theory. The analytical solution has been obtained by using Prandtl’s mixing length hypothesis. The results show that along the streamline direction, the axial velocity decreases gradually like a single jet and in the transverse direction, the velocity distribution changes as a cosinoidal function, in which the velocity amplitude decreases with increasing x, gradually approaching a flat profile. It is also shown that the distance at which the individual jets begin to merge increases with increasing pitch, s. For the special cases when the pitch, s is zero, the row of multiple jets becomes equivalent to a single jet. Finally, the predictive results are found to agree well with experimental data in the fully developed turbulent flow region.
LDA Measurements of Feed Annulus Effects on Combustor Liner Port Flows1
Authors: Spencer Adrian , McGuirk James J.
Published: July 2002

A detailed LDA experimental study is reported on the effect of variations in feed annulus conditions on port flow jet characteristics. The data are relevant to primary and dilution jet flows as found in gas-turbine combustor liners. Alteration of jet velocity ratios and associated bleed flows past the jet ports for a typical annulus height/port diameter configuration was observed to produce significant variations in separation regions in the annulus, distortions in downstream annulus profiles, and jet exit conditions. Profiles of jet exit velocity, flow angle, and turbulent kinetic energy distribution have been provided which should prove invaluable as boundary conditions for related CFD studies. For the first time the influence of swirl in the approach annulus was examined, at a level consistent with residual swirl passing down the annulus from compressor exit conditions. Noticeable deviations in jet characteristics were again observed, reducing jet entry angles by some 20 deg over the rear half of the port.