bluuebunny/crossref_metadata_2025 huggingface dataset:
Small firm organisational learning: comparing the perceptions of need and style among UK support service advisors and small firm managers
Authors: Chaston Ian , Badger Beryl , Sadler‐Smith Eugene
Published: July 2002

It is increasingly the case that within the academic literature, firms seeking to survive in rapidly changing and/or highly competitive markets are being advised to consider adopting an organisational learning philosophy as a strategy through which to develop new approaches to delivering greater customer value. This view is apparently shared by the UK Government, which has incorporated the concept of Lifelong Learning into its small firms support policy. This is despite the fact that to date in the academic literature, there is only limited anecdotal evidence of the positive contribution that organisational learning can make to enhancing the performance of firms. Surveys of small firm advisors and small manufacturing firms were undertaken. These surveys revealed significant differences of opinion between advisors and owner/managers over the need to utilise organisational learning to upgrade management practices. This survey also revealed that small firm advisors perceive most of their client firms as exhibiting a lower‐order learning style. The implications of these findings are discussed. A pilot scheme to embed a learning philosophy into SME sector is described and proposals presented on the needs for further research.
Synectics: A Problem‐solving Tool for Educational Leaders
Authors: Georgiou Stelios N.
Published: July 2002

Presents the theoretical foundations of the creative problem‐solving
technique known as Synectics. Points out the usefulness of this
technique for educational leaders and describes a five‐session training
programme that was developed and tested in Cyprus by the author. The
training programme, which is based on the Synectics literature, has
promising results with school principals and prospective organizational
leaders.
Organizational climate and teacher autonomy: implications for educational reform
Authors: Dondero Grace Marie
Published: July 2002

Shows how educational reform has been a persistent concern in the USA for decades. Recent reform initiatives have focused on teacher autonomy and teacher participation in school‐based decision making. Private sector and school research identify the importance of worker/teacher autonomy. This autonomy leads to a sense of ownership and empowerment where workers aim to grow within their profession and to seek increased responsibility. Believes real education reform must provide teachers with decision‐making responsibility and autonomy in educational matters including choice with respect to professional development. This can only be accomplished in a supportive and nurturing organization.
As they are portrayed: principals in film
Authors: Ross Thomas A.
Published: July 2002

This paper reports on the analysis of the principalship as portrayed in a sample of 48 films. The analysis reveals that, unlike the timid, obsequious pastor in the Western and the bullying marine sergeant in a war movie, for example, there is little that is stereotypic about the role of the school principal and the types of leadership practised; there is no single model of the “successful” (or, for that matter, “unsuccessful”) principal. Success, however defined, has been achieved by some but it has eluded others. Admittedly, one can readily identify common themes associated with the principalship, for example, the vesting of authority, the exercise of power, relationships with teachers, students and community, and so on. And yet, against this common backdrop, countless scenes have been enacted in which the role of the principal has been one of great variation. Portrayals of roles are, of course, the outcome of the interaction of author, scriptwriter, actor, director ‐ to name but some of those involved in the production of a film. Nevertheless, they provide at times quite extraordinary insights into others’ perceptions of both the role and the exercise of leadership in schools and school communities. For those involved in programs designed to prepare educationists for the principalship, considerable satisfaction is to be found in the variety of representations of this office that are displayed per medium of film. Films provide a legitimate basis on which to analyse leadership behaviour and from which a greater sensitivity to the role may be developed.
Market orientation applied to police service strategies
Authors: Drummond Graeme , Ensor John , Laing Andrew , Richardson Neil
Published: July 2002

The complexity of modern policing requires an accountable police service to operate in a diverse society, where support/trust must be earned by action and deed. The article examines the potential of market orientated strategies in facilitating policing initiatives, such as community policing and enhanced service quality. The work reviews the concept of market orientation and adopts a case study approach to research. Market orientated/customer focused strategies are examined in a range of public, private and international sectors. Findings outline a three‐stage “turnaround” process to enhance service quality and highlight the importance of market orientation in counteracting the concept of “unwilling/reluctant customers”. Draws on case studies from Inland Revenue, Richer Sounds plc and the New York Police Department.
Towards comparative educational administration: building the case for a cross‐cultural school‐based approach
Authors: Dimmock Clive , Walker Allan
Published: July 2002

Promotes and justifies a stronger comparative emphasis in the study of educational administration and management. Addresses questions such as, why adopt a comparative approach to educational administration? Why ground a comparative approach in culture? and, why focus on school organisation, leadership and management as the baseline unit for comparison? In systematically addressing these questions, the paper begins by acknowledging that comparative educational administration has, at best, a weak knowledge base. It goes on to clarify the potential importance of a comparative dimension to the field, and in particular, a comparative approach reflecting a cross‐cultural perspective. Finally, the paper briefly addresses a number of key issues which, it is argued, could inform initiatives to create a robust cross‐cultural approach to comparative educational administration
Perceptions, corrections and defections: implications for service recovery in the restaurant industry
Authors: Mack Rhonda , Mueller Rene , Crotts John , Broderick Amanda
Published: July 2002

Focusing on service failures can assist organizations in improving service quality and improving long‐term customer retention. This study examined consumer perceptions of their personal service failures experienced in the restaurant industry. While the study found a large percentage of the respondents to be very “forgiving” with respect to returning to the restaurant where they had experienced a failure, the data also indicate that those less likely to return had, in fact, perceived the failure as major and had judged the method the restaurant used to recover the failure as not very good. Implications are for identifying failure points in the service delivery process and identifying methods to prevent, as well as recover, these failures to prevent negative customer perceptions and the ensuing customer loss and potential negative word of mouth.
Similarity solutions for hydromagnetic mixed convection heat and mass transfer for Hiemenz flow through porous media
Authors: Chamkha Ali J. , Khaled Abdul‐Rahim A.
Published: July 2002

The problem of coupled heat and mass transfer by mixed convection in a linearly stratified stagnation flow (Hiemenz flow) in the presence of an externally applied magnetic field and internal heat generation or absorption effects is formulated. The plate surface is embedded in a uniform Darcian porous medium and is permeable in order to allow for possible fluid wall suction or blowing and has a power‐law variation of both the wall temperature and concentration. The resulting governing equations are transformed into similarity equations for the case of linearly varying wall temperature and concentration with the vertical distance using an appropriate similarity transformation. These ordinary differential equations are then solved numerically by an implicit, iterative, finite‐difference scheme. Comparisons with previously published work are performed and excellent agreement between the results is obtained. A parametric study of all involved parameters is conducted and a representative set of numerical results for the velocity and temperature profiles as well as the skin‐friction parameter, local Nusselt number, and the local Sherwood number is illustrated graphically to elucidate interesting features of the solutions.
Non‐homentropic flow generated by trains in tunnels with side branches
Authors: William‐Louis M.J.P. , Tournier C.
Published: July 2002

Describes the propagation of pressure waves when a train passes through a plain tunnel or tunnel equipped with side branches. A non‐homentropic one‐dimensional model is used to predict the flow generated. This model takes into consideration the train and tunnel geometry, the wall friction and heat transfer. The numerical calculation is performed using the classical method of characteristics. Near the train and tunnel ends, or at the junctions with the side branches, the flow is three dimensional. In the one‐dimensional theory, boundary conditions are applied to model the flows across these regions. The model used is validated by comparisons with experimental results. The use of airshafts to attenuate pressure waves is discussed.
Scenario methodology for teaching principles of emergency management
Authors: Alexander David
Published: July 2002

Scenarios are discussed in terms of their various uses in emergency planning and management. Their function in teaching programs is assessed with respect to various sorts of curricula for training emergency personnel. The format of scenarios is discussed and the potential for using the methodology creatively is explored. It is concluded that scenario methods are useful in developing such skills as time management, cognitive mapping, mediation, team management, and decision making under stress. A brief example of an emergency training scenario is presented and evaluated in terms of its teaching potential. Finally, scenarios are assessed in relation to other forms of modelling and simulation, such as table‐top games and field exercises, which are commonly used for training emergency managers.
Institutional performance in higher education: is quality a relevant concept?
Authors: Pounder James
Published: July 2002

Over the past two decades, institutions of higher education worldwide have come under pressure to demonstrate effective performance. Their response has been to borrow the quality concept from industry and place it at the centre of institutional performance assessment in higher education. This article describes a Hong Kong study which developed valid and reliable organisational effectiveness self rating scales for higher educational institutions. In the course of developing these scales, the relevance of quality to institutional performance assessment was examined. In failing to produce a valid and reliable effectiveness scale for a quality dimension, the study highlighted the shortcomings of the quality concept particularly as a basis for the comparative assessment of institutional performance. The study also indicated a methodology for identifying concepts which may provide a firmer base than quality for such comparisons.
Internet‐based EDI trust and security
Authors: Ratnasingham Pauline
Published: July 2002

While the term “electronic commerce” was a buzzword in the early 1990s, it has fast become an essential business tool as we approach the next century. In traditional EDI many of these transactions already occur electronically, but require prior arrangements and dedicated lines or VANs. The resulting costs and lead times of the VANs create entry barriers to widespread small business participation, hindering expansion of EDI beyond large organisations and their major trading partners. Conversely, more organisations are using or considering using the Internet for electronic commerce and EDI. The Internet‐based EDI is viable and is becoming an essential element of value‐added‐network services. The downside is that Internet EDI lacks security and does not guarantee delivery. The potential for fraud and deception is far greater. The ability to tap into information around the clock from almost anywhere in the world is perceived as a benefit of electronic commerce. Misconceptions must be overcome before it can be deemed suitable for electronic commerce. Commonly expressed concerns include reliability, security, scalability, ease of use and payment.
A services‐marketing perspective on e‐retailing: implications for e‐retailers and directions for further research
Authors: Kolesar Mark B. , Wayne Galbraith R.
Published: July 2002

There has been an explosion in the number of retail Web sites since 1995, e‐retail offering shares a few common elements specifically a product search facility (often augmented by a product evaluation facility), an on‐line purchase function and a product delivery capability. There is a body of theory and empirical research in the study of customer loyalty drivers in the services sector, which demonstrates that customers evaluate services on the basis of tangibles, responsiveness, empathy, assurance, reliability and control. These service qualities depend on the customer’s perception of the overall service experience. The most influential element in the service experience is the relationship between the service provider and the customer. The Internet is a poor service delivery medium, it lacks the capacity for direct personal interaction enjoyed by non‐Internet based services. Sets out a number of marketing and Website design implications for e‐retailers and suggests means by which e‐retailers can manage customer perceptions to increase sales and develop greater customer loyalty.
Total quality management and the Deming approach to quality management
Authors: Petersen Peter B.
Published: July 2002

This article discusses the total quality management (TQM) movement and then elaborates about W. Edwards Deming’s experiences and views. Finally, there is a comparison of total quality management and the Deming approach to quality management. The TQM movement was attractive to many organizations during the 1980s and the first half of the 1990s. To succeed, total quality management had many long‐term require‐ments. One of these was that top management must have a passion for the subject. Without this sustained passion top management’s attention and energy towards TQM would be diverted to other pressing needs. While Deming insisted that there was no “instant pudding”, many consultants in establishing themselves with a client suggested short‐term gains. Because of this search for short‐term gains, process improvement and reductions in cycle time became very popular and in some cases a final objective. Unfortunately, after they ran their short‐term course, many efforts collapsed and TQM was often declared a failure.
The application of surface generated interpolation models for the prediction of residential property values
Authors: McCluskey William J. , Deddis William G. , Lamont Ian G. , Borst Richard A.
Published: July 2002

The aim of this paper is to attempt to measure the effect of location on residential house prices and to endeavour to integrate spatial and aspatial data in terms of developing a hybrid predictive model. The research methodology investigates the traditional hedonic approach to modelling location using multiple regression techniques. Alternative approaches are considered which specifically model the spatial distribution of house prices with the objective of developing location adjustment factors. These approaches are based on the development of surface response techniques such as inverse distance weighting and universal kriging. The results generated from the surfaces created are then calibrated within MRA.
The financial instruments of capital accounting in local authorities
Authors: Deakin Mark
Published: July 2002

The paper examines the development of the financial instruments (land audits, property reviews, information systems, registers and approaches to valuation) required to replace the expenditure‐driven logic of public sector finance with the system of capital accounting in local authorities advocated by the Chartered Institute of Public Finance and Accountancy. The examination draws on the findings of a research project undertaken to survey the steps local authorities have taken to develop the property registers and valuation procedures for such purposes. It highlights the critical role property valuation plays in introducing a system of capital accounting that ensures that the financing of the public sector is not expenditure‐driven, but subject to value‐for‐money tests, and meets the economy and efficiency criteria which this requires.
Structure of soybean seed coat peroxidase: A plant peroxidase with unusual stability and haem‐apoprotein interactions
Authors: Henriksen Anette , Mirza Osman , Indiani Chiara , Teilum Kaare , Smulevich Giulietta , Welinder Karen G. , Gajhede Michael
Published: July 2002

Soybean seed coat peroxidase (SBP) is a peroxidase with extraordinary stability and catalytic properties. It belongs to the family of class III plant peroxidases that can oxidize a wide variety of organic and inorganic substrates using hydrogen peroxide. Because the plant enzyme is a heterogeneous glycoprotein, SBP was produced recombinant in Escherichia coli for the present crystallographic study. The three‐dimensional structure of SBP shows a bound tris(hydroxymethyl)aminomethane molecule (TRIS). This TRIS molecule has hydrogen bonds to active site residues corresponding to the residues that interact with the small phenolic substrate ferulic acid in the horseradish peroxidase C (HRPC):ferulic acid complex. TRIS is positioned in what has been described as a secondary substrate‐binding site in HRPC, and the structure of the SBP:TRIS complex indicates that this secondary substrate‐binding site could be of functional importance. SBP has one of the most solvent accessible δ‐meso haem edge (the site of electron transfer from reducing substrates to the enzymatic intermediates compound I and II) so far described for a plant peroxidase and structural alignment suggests that the volume of Ile74 is a factor that influences the solvent accessibility of this important site. A contact between haem C8 vinyl and the sulphur atom of Met37 is observed in the SBP structure. This interaction might affect the stability of the haem group by stabilisation/delocalisation of the porphyrin π‐cation of compound I.
Detecting Homogeneous Segments in DNA Sequences by Using Hidden Markov Models
Authors: Boys Richard J. , Henderson Daniel A. , Wilkinson Darren J.
Published: July 2002

In recent years there has been a rapid growth in the amount of DNA being sequenced and in its availability through genetic databases. Statistical techniques which identify structure within these sequences can be of considerable assistance to molecular biologists particularly when they incorporate the discrete nature of changes caused by evolutionary processes. This paper focuses on the detection of homogeneous segments within heterogeneous DNA sequences. In particular, we study an intron from the chimpanzee α-fetoprotein gene; this protein plays an important role in the embryonic development of mammals. We present a Bayesian solution to this segmentation problem using a hidden Markov model implemented by Markov chain Monte Carlo methods. We consider the important practical problem of specifying informative prior knowledge about sequences of this type. Two Gibbs sampling algorithms are contrasted and the sensitivity of the analysis to the prior specification is investigated. Model selection and possible ways to overcome the label switching problem are also addressed. Our analysis of intron 7 identifies three distinct homogeneous segment types, two of which occur in more than one region, and one of which is reversible.
Whisker maps of neuronal subclasses of the rat ventral posterior medial thalamus, identified by whole‐cell voltage recording and morphological reconstruction
Authors: Brecht Michael , Sakmann Bert
Published: July 2002

Whole‐cell voltage recordings were made in vivo in the ventral posterior medial nucleus (VPM) of the thalamus in urethane‐anaesthetised young (postnatal day 16–24) rats. Receptive fields (RFs) on the whisker pad were mapped for 31 neurones, and 10 cells were recovered for morphological reconstruction of their dendritic arbors. Most VPM neurones had antagonistic subthreshold RFs that could be divided into excitatory and inhibitory whiskers. VPM cells comprised different classes, the most frequently occurring being single‐whisker excitation (SWE) and multi‐whisker excitation (MWE) cells. In SWE cells (36 % of VPM neurones), only principal whisker (PW) deflection evoked an EPSP and was followed by a single action potential (AP) or remained subthreshold. The depolarisation was terminated by a large, delayed IPSP. A stimulus evoked on average 0.74 ± 0.46 APs (mean ±s.d.) with short latency (8.1 ± 1.0 ms) and small temporal scatter (0.31 ± 0.23 ms dispersion of 50 % of the first APs). In MWE cells (29 % of VPM neurones), deflection of several whiskers evoked EPSPs. PW responses were either subthreshold EPSPs or consisted of an EPSP followed by one or several APs (0.96 ± 0.99 APs per stimulus). AP responses were often associated with putative low‐threshold calcium‐dependent regenerative potentials and were followed by a small delayed IPSP. AP responses had a longer latency (12.3 ± 2.6 ms) and larger temporal scatter (2.5 ± 1.6 ms) than responses of SWE cells. MWE cells had a lower input resistance than SWE cells. The elongation of dendritic arbors along the representation fields of rows and arcs in VPM barreloids was weakly correlated with the subthreshold RF elongation along whisker rows and arcs, respectively. Evoked EPSP‐AP responses exhibited a sharper directional tuning than subthreshold EPSPs, which in turn exhibited a sharper directional tuning than IPSPs. In conclusion, we document two main classes of VPM neurones. SWE cells responded with a precisely timed single AP to the deflection of the PW. In contrast, MWE cell RFs were more broadly tuned and the temporally dispersed multiple AP responses of these cells represented the degree of collective deflection of the PW and several adjacent whiskers.
A novel algorithm to remove electrical cross‐talk between surface EMG recordings and its application to the measurement of short‐term synchronisation in humans
Authors: Kilner J. M. , Baker S. N. , Lemon R. N.
Published: July 2002

Pairs of discharges of single motor units recorded in the same or different muscles often show synchronisation above chance levels. If large numbers of units are synchronous within and between muscles then the synchrony will be measurable in population recordings such as surface EMG. Measuring synchrony between surface EMG recordings has a number of practical and scientific advantages compared with single motor units recorded from intramuscular electrodes. However, the measurement of such synchrony in the time domain between surface EMGs is complicated because the recordings are contaminated by electrical cross‐talk. In this study we recorded surface EMG simultaneously from five hand and forearm muscles during a precision grip task. Using a novel ‘blind signal separation’ algorithm, we were able to remove electrical cross‐talk. The cross‐talk‐corrected EMGs could then be used to assess task‐dependent modulation in both oscillatory (15‐30 Hz) and non‐oscillatory synchrony (all other frequencies). In agreement with previous studies, the oscillatory component was maximal during steady holding but abolished during movement. By contrast, the non‐oscillatory component of the EMG synchrony appeared remarkably constant throughout all phases of the task. We conclude that surface EMG recordings can be of considerable use in the assessment of population synchrony changes, providing that electrical cross‐talk between nearby channels is removed using a statistical signal processing technique. Our results show a striking difference in the task‐dependent modulation of oscillatory and non‐oscillatory synchrony between muscles during a dynamic precision grip task.
Effects of butyrate on active sodium and chloride transport in rat and rabbit distal colon
Authors: Vidyasagar S. , Ramakrishna B. S.
Published: July 2002

Short chain fatty acids, particularly butyrate, stimulate electroneutral NaCl absorption from the colon. Their effect in colonic epithelia lacking basal electroneutral NaCl absorption is unknown. Butyrate is also reported to inhibit active Cl− secretion in the colon. The present studies were undertaken to investigate the inter‐relationships between the effects of butyrate on active Na+ and Cl− transport in the colon. Studies were carried out in rabbit distal colon (known to have predominant electrogenic Na+ absorption), rat distal colon (characterised by electroneutral Na+ absorption), and hyperaldosteronaemic rat distal colon (characterised by electrogenic Na+ absorption). The effect of cholera toxin (CT) was also noted. Potential difference, short‐circuit current (ISC) and fluxes of Na+ and Cl− were measured in stripped mucosa under voltage‐clamp conditions. Butyrate stimulated electroneutral Na+ and Cl− absorption in distal colon of normal and salt‐depleted rats, and stimulated Na+ absorption in rabbit distal colon. Amiloride (10−4m) or CT did not inhibit this process. In rabbit distal colon, stimulation of Na+ absorption by butyrate was not dependent on the presence of Cl− in the medium. Butyrate significantly decreased conductance, decreased flux of sodium from serosa to mucosa (particularly in rabbit distal colon), and decreased ISC. Net Cl− secretion, induced by CT, was completely inhibited by butyrate. Stimulation of Na+ absorption was independent of exposure to CT. Bumetanide reversed net Cl− secretion to net absorption, but did not alter Na+ or Cl− fluxes in tissues exposed to butyrate. Thus butyrate stimulates active Na+ absorption in colonic epithelia, with or without expression of basal Na+‐H+ exchange. Independently, butyrate inhibits active Cl− secretion induced by cAMP in these epithelia.
The cutaneous uptake of atmospheric oxygen contributes significantly to the oxygen supply of human dermis and epidermis
Authors: Stücker M. , Struk A. , Altmeyer P. , Herde M. , Baumgärtl H. , Lübbers D. W.
Published: July 2002

It has been known since 1851 that atmospheric oxygen is taken up by the human epidermis. The contribution to total respiration is negligible. Until now the significance for the local oxygen supply of the skin has remained unknown. With a newly developed sensor, the oxygen fluxoptode, it has become possible to make local measurements of the transcutaneous oxygen flux (tcJO2). In this study the sensor was calibrated so that absolute values of tcJO2 could be reported. At rest, tcJO2 was determined on normal, humidified skin on the volar forearm of 20 volunteers of different age groups. In order to evaluate the contribution of the blood flow to the oxygen supply of the skin, tcJO2 was recorded at the end of a 5 min suprasystolic occlusion of the forearm. At normal skin surface partial oxygen pressure (163 ± 9 Torr), tcJO2 was 0.53 ± 0.27 ml O2 min−1 m−2. A 5 min interruption of blood flow resulted in an increase of 9.5 ± 6.3 % in tcJO2. The value of tcJO2 was unaffected by the age of the subject. Published data on the oxygen diffusion properties of skin and simulations of intracutaneous profiles of oxygen partial pressure indicated that under these conditions, the upper skin layers to a depth of of 0.25–0.40 mm are almost exclusively supplied by external oxygen, whereas the oxygen transport of the blood has a minor influence. As a consequence, a malfunction in capillary oxygen transport cannot be the initiator of the development of superficial skin defects such as those observed in chronic venous incompetence and peripheral arterial occlusive disease.
Titin‐based contribution to shortening velocity of rabbit skeletal myofibrils
Authors: Minajeva Ave , Neagoe Ciprian , Kulke Michael , Linke Wolfgang A.
Published: July 2002

The shortening velocity of skeletal muscle fibres is determined principally by actomyosin cross‐bridges. However, these contractile elements are in parallel with elastic elements, whose main structural basis is thought to be the titin filaments. If titin is stretched, it may contribute to sarcomere shortening simply because it can recoil ‘passively’. The titin‐based contribution to shortening velocity (Vp) was quantified in single rabbit psoas myofibrils. Non‐activated specimens were rapidly released from different initial sarcomere lengths (SLs) by various step amplitudes sufficient to buckle the myofibrils; Vp was calculated from the release amplitude and the time to slack reuptake. Vp increased progressively (upper limit of detection, ∼60 μm s−1 sarcomere−1) between 2.0 and 3.0 μm SL, albeit more steeply than passive tension. At very low passive tension levels already (< 1–2 mN mm−2), Vp could greatly exceed the unloaded shortening velocity measured in fully Ca2+‐activated skinned rabbit psoas fibres. Degradation of titin in relaxed myofibrils by low doses of trypsin (5 min) drastically decreased Vp. In intact myofibrils, average Vp was faster, the smaller the release step applied. Also, Vp was much higher at 30 °C than at 15 °C (Q10: 2.0, 3.04 or 6.15, for release steps of 150, 250 or 450 nm sarcomere−1, respectively). Viscous forces opposing the shortening are likely to be involved in determining these effects. The results support the idea that the contractile system imposes a braking force onto the passive recoil of elastic structures. However, elastic recoil may aid active shortening during phases of high elastic energy utilization, i.e. immediately after the onset of contraction under low or zero load or during prolonged shortening from greater physiological SLs.
Synaptic transmission in the auditory brainstem of normal and congenitally deaf mice
Authors: Oleskevich Sharon , Walmsley Bruce
Published: July 2002

The deafness (dn/dn) mutant mouse provides a valuable model of human congenital deafness. We investigated the properties of synaptic transmission in the anteroventral cochlear nucleus (AVCN) of normal and congenitally deaf dn/dn mice. Excitatory postsynaptic currents (EPSCs) were evoked by focal stimulation of single auditory nerve fibres, and measured by whole‐cell recordings from neurones in AVCN slices (mean postnatal age = P13). Absolute amplitudes of both AMPA‐ and NMDA‐mediated components of evoked EPSCs were greater (170 %) in deaf versus control animals. Enhanced transmission in deaf mice was due to a presynaptic mechanism. Variance‐mean analysis revealed that the probability of transmitter release was significantly greater in deaf (Pr= 0.8) versus control animals (Pr= 0.5). Following high frequency stimulation, deaf mice showed a greater depression of evoked EPSCs, and a significant increase in the frequency of delayed‐release (asynchronous) miniature EPSCs (aEPSCs) (deaf 100 Hz vs. control 7 Hz). The acetoxymethyl ester of EGTA (EGTA‐AM) blocked the increase in miniature aEPSCs and returned tetanic depression to control values. In deaf mice, reduction of mean Pr using cadmium caused an expected increase in paired‐pulse ratio (PPR). However, in the same cells, a similar reduction in release by EGTA‐AM did not result in a change in PPR, demonstrating that a change may occur in Pr without a concomitant change in PPR. In many respects, transmission in deaf mice was found to be remarkably similar to control mice, implying that many parameters of synaptic transmission develop normally in these animals. The two significant differences (higher Pr and asynchronous release in deaf mice) could both be reversed by the addition of EGTA‐AM, suggesting that endogenous calcium buffering may be impaired or undeveloped in the presynaptic terminals of the auditory nerve in deaf mice.
Protein kinase C modulation of recombinant ATP‐sensitive K+ channels composed of Kir6.1 and/or Kir6.2 expressed with SUR2B
Authors: Thorneloe Kevin S. , Maruyama Yoshiaki , Malcolm A. Todd , Light Peter E. , Walsh Michael P. , Cole William C.
Published: July 2002

The molecular identity of smooth muscle ATP‐sensitive K+ channels (KATP) is not established with certainty. Patch clamp methods were employed to determine if recombinant KATP channels composed of Kir6.1 and SUR2B subunits expressed by human embryonic kidney (HEK293) cells share an identical modulation by protein kinase C (PKC) with the vascular KNDP subtype of KATP channel. The open probability of Kir6.1/SUR2B channels was determined before and after sequential exposure to pinacidil (50 μM) and the combination of pinacidil and phorbol 12,13‐dibutyrate (PdBu; 50 nm). Treatment with PdBu caused a decline in channel activity, but this was not seen with an inactive phorbol ester, 4α‐phorbol 12,13‐didecanoate (PdDe; 50 nm). Angiotensin II (0.1 μM) induced a similar inhibition of Kir6.1/SUR2B channels in cells expressing angiotensin AT1 receptors. The effects of PdBu and angiotensin II were blocked by the PKC inhibitor, chelerythrine (3 μM). Purified PKC inhibited Kir6.1/SUR2B activity (in 0.5 mm ATP/ 0.5 mm ADP), and the inhibition was blocked by a specific peptide inhibitor of PKC, PKC(19‐31). In contrast, PdBu increased the activity of recombinant KATP channels composed of Kir6.2 and SUR2B, or the combination of Kir6.1, Kir6.2 and SUR2B subunits. The results indicate that the modulation by PKC of Kir6.1/SUR2B, but not Kir6.2/SUR2B or Kir6.1‐Kir6.2/SUR2B channel gating mimics that of native vascular KNDP channels. Physiological inhibition of vascular KATP current by vasoconstrictors which utilize intracellular signalling cascades involving PKC is concluded to involve the modulation of KNDP channel complexes composed of four Kir6.1 and their associated SUR2B subunits.
Substrate Deformation Levels Associated With Routine Physical Activity Are Less Stimulatory to Bone Cells Relative to Loading-Induced Oscillatory Fluid Flow
Authors: You J. , Yellowley C. E. , Donahue H. J. , Zhang Y. , Chen Q. , Jacobs C. R.
Published: July 2002

Although it is well accepted that bone tissue metabolism is regulated by external mechanical loads, it remains unclear to what load-induced physical signals bone cells respond. In this study, a novel computer-controlled stretch device and parallel plate flow chamber were employed to investigate cytosolic calcium Ca2+i mobilization in response to a range of dynamic substrate strain levels (0.1–10 percent, 1 Hz) and oscillating fluid flow (2 N/m2, 1 Hz). In addition, we quantified the effect of dynamic substrate strain and oscillating fluid flow on the expression of mRNA for the bone matrix protein osteopontin (OPN). Our data demonstrate that continuum strain levels observed for routine physical activities (<0.5 percent) do not induce Ca2+i responses in osteoblastic cells in vitro. However, there was a significant increase in the number of responding cells at larger strain levels. Moreover, we found no change in osteopontin mRNA level in response to 0.5 percent strain at 1 Hz. In contrast, oscillating fluid flow predicted to occur in the lacunar–canalicular system due to routine physical activities (2 N/m2, 1 Hz) caused significant increases in both Ca2+i and OPN mRNA. These data suggest that, relative to fluid flow, substrate deformation may play less of a role in bone cell mechanotransduction associated with bone adaptation to routine loads. [S0148-0731(00)01204-8]
A Review of Polymer Materials for Solar Water Heating Systems
Authors: Raman Raghu , Mantell Susan , Davidson Jane , Wu Chunhui , Jorgensen Gary
Published: July 2002

This paper summarizes current research aimed at using polymer materials for glazing and heat exchanger components in solar water heating systems. Functional requirements, relevant polymer properties and an approach for selecting polymers are described for each of these components. Glazing must have high transmittance across the solar spectrum and withstand long term exposure to ultraviolet (UV) light. Candidate glazing materials were tested outdoors for one year in Golden, Phoenix and Miami, as well as exposed for over 300 days in an accelerated testing facility at a concentration ratio of two at the National Renewable Energy Laboratory. Measurements of hemispherical transmittance indicate that a 3.35 mm polycarbonate sheet with a thin film acrylic UV screen provides good transmittance without excessive degradation. The primary challenge to designing a polymer heat exchanger is selecting a polymer that is compatible with potable water and capable of withstanding the high pressure and temperature requirements of domestic hot water systems. Polymers certified for hot water applications by the National Sanitation Foundation or currently used in heat exchangers and exhibit good high temperature characteristics were compared on the basis of a merit value (thermal conductance per unit area per dollar) and manufacturer’s recommendations. High temperature nylon (HTN), polypropylene (PP) and cross linked polypropylene (PEX) are recommended for tube components. For structural components (i.e. headers), glass reinforced high temperature nylon (HTN), polyphthalamide (PPA), polyphenylene sulphide (PPS) and polypropylene (PP) are recommended. [S0199-6231(00)00902-3]
Fatigue Life Prediction of Thick-Section S2-Glass/Vinyl-Ester Composites Under Flexural Loading1
Authors: Mahfuz Hassan , Zaman Kamruz , Haque Anwarul , Foy Costee , Mohamed Hisham , Jeelani Shaik
Published: July 2002

Fatigue life prediction of S2-Glass/Vinyl-ester composites has been studied analytically using the fatigue modulus concept. Traditionally it is assumed that the fatigue modulus degradation is a function of loading cycle only. In our present investigation, it is found that the fatigue modulus is not only a function of loading cycle but also a function of applied stress level and thickness of the specimen. Using this concept, a practical and applicable method for predicting fatigue life is established. The method requires two distinct parameters that arise from the mathematical formulation. These two parameters are determined in two ways. In one case, the parameters are determined using failure cycle numbers at two different stress levels. In the other case, the parameters are determined using fatigue modulus values at two different cycles at a particular stress level. These material parameters have been determined experimentally using both the procedures. Utilizing the experimental data two appropriate functions for these two material parameters were obtained and incorporated into the life prediction equation. Fatigue life predictions using this method have been found to be within 10 percent of the experimental values. [S0094-4289(00)02404-X]
Impact of Using Biodiesels of Different Origin and Additives on the Performance of a Stationary Diesel Engine
Authors: Serdari A. , Fragioudakis K. , Kalligeros S. , Stournas S. , Lois E.
Published: July 2002

With the exception of rape seed oil which is the principal raw material for biodiesel Fatty Acid Methyl Esters, (FAME) production, sunflower oil, corn oil, and olive oil, which are abundant in Southern Europe, along with some wastes, such as used frying oils, appear to be attractive candidates for biodiesel production. In this paper fuel consumption and exhaust emission measurements from a single cylinder, stationary diesel engine are described. The engine was fueled with fuel blends containing four different types of biodiesel, at proportions up to 100 percent; the further impact of the usage of two specific additives was also investigated. The four types of biodiesel appeared to have equal performance and irrespective of the raw material used for their production, their addition to the traditional diesel fuel improved the particulate matter emissions. The results improve further when specific additive combinations are used. [S0742-4795(00)00604-9]
Performance Simulation of Sequentially Turbocharged Marine Diesel Engines With Applications to Compressor Surge
Authors: Chesse Pascal , Hetet Jean-Franc¸ois , Tauzia Xavier , Roy Philippe , Inozu Bahadir
Published: July 2002

This paper presents the SELENDIA code designed for the simulation of marine diesel engines. Various measured and simulated results are compared for the performance of a sequentially turbocharged marine diesel engine during a switch from one to two turbochargers. The results show a good agreement between measured and simulated data. Surge loops that are experimentally observed in case of an anomaly are analyzed using simulated results. Finally, the predictive capabilities of the simulation code are utilized to investigate the influence of the inlet manifold volume on the engine and air charging system performance with a special focus on compressor surge. [S0742-4795(00)01104-2]
The Influence of Technical Surface Roughness Caused by Precision Forging on the Flow Around a Highly Loaded Compressor Cascade
Authors: Leipold Robert , Boese Matthias , Fottner Leonhard
Published: July 2002

A highly loaded compressor cascade, which features a chord length ten times larger than in real turbomachinery, is used to perform an investigation of the influence of technical surface roughness. The surface structure of a precision forged blade was engraved in two 0.3-mm-thick sheets of copper with the above-mentioned enlarging factor (Leipold and Fottner, 1996). To avoid additional effects due to thickening of the blade contour, the sheets of copper are applied as inlays to the pressure and suction side. At the high-speed cascade wind tunnel, the profile pressure distribution and the total pressure distribution at the exit measurement plane were measured for the rough and the smooth blade for a variation of inlet flow angle and inlet Reynolds number. For some interesting flow conditions, the boundary layer development was investigated with laser-two-focus anemometry and one-dimensional hot-wire anemometry. At low Reynolds numbers and small inlet angles, a separation bubble is only slightly reduced due to surface roughness. The positive effect of a reduced separation bubble is overcompensated by a negative influence of surface roughness on the turbulent boundary layer downstream of the separation bubble. At high Reynolds numbers, the flow over the rough blade shows a turbulent separation leading to high total pressure loss coefficients. The laser-two-focus measurements indicate a velocity deficit close to the trailing edge, even at flow conditions where positive effects due to a reduction of the suction side separation have been expected. The turbulence intensity is reduced close downstream of the separation bubble but increased further downstream due to surface roughness. Thus the rear part of the blade but not the front part reacts sensitively on surface roughness. [S0889-504X(00)01302-7]
Torsion of a Viscoelastic Cylinder
Authors: Batra R. C. , Yu J. H.
Published: July 2002

Finite torsional deformations of an incompressible viscoelastic circular cylinder are studied with its material modeled by two constitutive relations. One of these is a linear relation between the determinate part of the second Piola-Kirchhoff stress tensor and the time history of the Green-St. Venant strain tensor, and the other a linear relation between the deviatoric Cauchy stress tensor and the left Cauchy-Green tensor, its inverse, and the time history of the relative Green-St. Venant strain tensor. It is shown that the response predicted by the latter constitutive relation is in better agreement with the test data, and this constitutive relation is used to compute energy dissipated during torsional oscillations of the cylinder. [S0021-8936(00)00502-X]
A Simultaneous Numerical Solution for the Lubrication and Dynamic Stability of Noncontacting Gas Face Seals
Authors: Green Itzhak , Barnsby Roger M.
Published: July 2002

A numerical solution is presented for the dynamic analysis of gas lubricated noncontacting mechanical face seals having a single grounded flexibly mounted stator. Seal dynamics is solved in axial and angular modes of motion. Both the Reynolds equation and the equations of motion are arranged into a single state space form, allowing the fluid film lubrication and the dynamics to be solved simultaneously. The resulting set of equations is solved using a high-order multistep ordinary differential equation solver, yielding a complete simulation for the seal dynamic behavior. Examples of seal motion are given in detailed transient responses. The stability threshold is investigated to gauge the influence of seal parameters such as inertia, speed, coning, and the direction of sealed pressure drops. The results show two modes of instability: (1) When the inertia effect is larger than a critical value, the natural response of the seal grows monotonically in a half-frequency-whirl mode. (2) When the seal coning is less than some critical value in an outside pressurized seal, the minimum film thickness diminishes because of hydrostatic instability, and face contact occurs. Conversely, an inside pressurized seal is shown to be hydrostatically stable and have a superior dynamic response at any coning.
Joint Clearances With Lubricated Long Bearings in Multibody Mechanical Systems
Authors: Ravn P. , Shivaswamy S. , Alshaer B. J. , Lankarani Hamid M.
Published: July 2002

Proper modeling of joint clearance is of great importance in the analysis and design of multibody mechanical systems. The clearance may be due to wear or imperfection in manufacturing. When there is no lubricant in the clearance, solid-to-solid contact occurs. The impulse due to contact between the links is transmitted throughout the system. The presence of a lubricant avoids such contact, as the hydrodynamic forces developed by the lubricant film support the loads acting on the bodies and prevent the bodies from coming into contact. In this paper, an analysis of revolute joint clearances in multibody mechanical systems with and without lubricant is presented. Squeeze as well as viscous effects are considered utilizing the hydrodynamic theory of lubrication in long bearings. Unlike the traditional machine design approach, the instantaneous lubricant forces are the unknown and evaluated in terms of the known geometrical position and velocity of the journal and bearing. In the case of analysis of a joint clearance with no lubricant, a modified Hertzian relation is used to model the impact or contact between the journal and bearing, which includes a hysteresis damping term to account for the energy dissipation during impact. The methodology is applied for the analysis of a slider-crank mechanism having a clearance in the piston pin. The simulations are carried out with and without lubricant and the results are compared. It is shown that the lubricant results in a steady motion with fewer peaks in the required cranking moment for the system. [S1050-0472(00)01804-3]