bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchrotron-radiation X-ray topography of surface strain in large-diameter silicon wafers
Authors: Kawado S. , Iida S. , Yamaguchi S. , Kimura S. , Hirose Y. , Kajiwara K. , Chikaura Y. , Umeno M.
Published: July 2002

Using a 300 mm-wide monochromatic X-ray beam obtained at beamline BL20B2 of SPring-8, the difference in surface-strain distribution caused by various steps of silicon-wafer manufacturing, i.e. slicing, lapping, etching, grinding and polishing, was studied. The asymmetric 511 reflection of 21.45 keV X-rays, incident at a glancing angle of 0.26°, was used to obtain topographs over the whole surface of a 200 mm-diameter (100) CZ silicon wafer. Differences in crystallinity and in warp between the surfaces at different steps of the manufacturing process (firstly after the lapping following the slicing, and then after successive etching, grinding and polishing) were clearly observed. The former gave a topographic image over the whole area with a one-shot exposure because of their wide rocking curves (50–70 arcsec FWHM), which indicate poor crystallinity. The latter, on the other hand, showed sharper curves (4–5 arcsec FWHM), which indicate good crystallinity in local areas, and the existence of warp, and therefore required step scanning of ω-rotation to cover the whole surface in topography measurements. The effect of each step in the process is also discussed.
Hard X-ray microbeam experiments with a sputtered-sliced Fresnel zone plate and its applications
Authors: Kamijo N. , Suzuki Y. , Awaji M. , Takeuchi A. , Takano H. , Ninomiya T. , Tamura S. , Yasumoto M.
Published: July 2002

Hard X-ray microbeam experiments with sputtered-sliced Fresnel zone plates have been performed. Zone plates with an outermost zone width of 0.25 µm (#FZP1) and 0.1 µm (#FZP2) were fabricated and evaluated. In a scanning X-ray microscopy experiment, a line-and-space pattern with structure as fine as 0.1 µm was resolved using #FZP2 at an X-ray wavelength of 1 Å. As an application of the microbeam technique, a two-dimensional distribution of constituent elements in forensic samples has been obtained (e.g. section view of human and elephant hairs) using fluorescent scanning microscopy.
Plane-wave X-ray topography and its application at SPring-8
Authors: Iida Satoshi , Chikaura Yoshinori , Kawado Seiji , Kimura Shigeru
Published: July 2002

Plane-wave X-ray topography experiments were carried out at a 200 m-long beamline, BL20B2, at SPring-8. Relatively high-energy X-rays of 30 keV with an angular divergence of about 0.01 arcsec were produced by using only one collimator crystal. FZ-Si and CZ-Si wafers were characterized in transmission geometry (Laue case). Clear oscillatory profiles in rocking curves of the FZ-Si crystal were observed. Plane-wave topographic images of dislocations, growth striations and grown-in microdefects in the CZ-Si crystals were obtained. The dependence of the topographic images of the lattice defects on the sample–photoplate distance was also studied.
N,N′,N′′,N′′′-Tetrakis(1-naphthylmethyl)-1,4,8,11-tetraazacyclotetradecane
Authors: Kubo Kanji , Yamamoto Emi , Sakurai Tadamitsu , Mori Akira
Published: July 2002

Molecules of the title compound, C54H56N4, are centrosymmetric and adopt a conformation with two naphthylmethyl groups above the cyclam ring and the remaining two below. Packing with intermolecular π–π interaction between naphthalene planes is observed.
Bis[1,2-bis(diphenylphosphino)ethane-P,P′](dithioformato-S,S′)technetium tris(benzene) solvate
Authors: Bryan Jeffrey C. , Burrell Anthony K. , Kubas Gregory J.
Published: July 2002

Two Tc-containing products were isolated from the reaction between CS2and the electron-deficient complex TcCl(dppe)2. The title dithioformate complex, [Tc(S2CH)(dppe)2]·3C6H6, where dppe is 1,2-bis(diphenylphosphino)ethane (C26H24P2), exhibits Tc—P bond lengths ranging from 2.3566 (14) to 2.3884 (14) Å, which are little shorter than normally found. The other product is [TcCl(CS)(dppe)2], and is the first reported Tc–thiocarbonyl complex.
A linear supramolecular array of {[Mn(H2O)2(15-crown-5)]Br2}n
Authors: Reid Howard O. N. , Kahwa Ishenkumba A. , Mague Joel T. , McPherson Gary L.
Published: July 2002

Diaqua(1,4,7,10,14-pentaoxacyclopentadecane)manganese(II) dibromide, [Mn(C10H20O5)(H2O)2]Br2, prepared in a search for emissive MnIIions in unusual coordination environments, contains the metal ion encircled by the crown ether ligand, with the water molecules intransaxial positions. Hydrogen bonding between these and the Br−counter-ions forms chains of cations running approximately parallel toa.
4-Nitrophenanthrene
Authors: Taylor Max R. , Thompson Malcolm J.
Published: July 2002

This study at 168 K shows that in the crystal structure of C14H9NO2, the plane of the nitro group is inclined at 72.2 (7)° to the plane of the attached six-membered ring. The phenanthrene system is significantly non-planar.
9β,11β-Epoxy-3β-hydroxy-5α-androstan-17-one
Authors: Novoa de Armas Héctor , Peeters Oswald M. , Blaton Norbert M. , De Ranter Camiel J. , Ruíz Garcia José A. , Reyes Moreno Mayra , Alvarez Ginarte Yoanna M.
Published: July 2002

In the title compound, C19H28O3, the ester linkage in ringAis equatorial. The six-membered ringsAandBhave chair conformations, but ringCcan be better described as a half-chair. The five-membered ringDadopts a 14α-envelope conformation. TheA/B,B/CandC/Dring junctions are alltrans. The packing of the molecules is assumed to be dictated mainly by intermolecular hydrogen bonds. There is an intramolecular C—H...O interaction between the O11 atom of the epoxy group and the methyl C18 group.
N,N′-Ethylenebis(p-toluenesulfonamide)
Authors: Gajadhar-Plummer Alison S. , Kahwa Ishenkumba A. , Mague Joel T.
Published: July 2002

The title compound, C16H20N2O4S2, crystallizes in a `partially extended' conformation, with crystallographically imposed centrosymmetry and intermolecular N—H...O hydrogen bonding.
Passivity and passivity breakdown of zinc anode in sulphate solutions
Authors: Abd El Aal E.E.
Published: July 2002

The electrochemical behaviour of zinc in different concentrations of Na2SO4 (pH = 6.0) was investigated using the potentiodynamic anodic polarization single sweep and cyclic voltammogram techniques. The anodic portion is characterized by one distinct peak corresponding to Zn(OH)2 or ZnO. This is followed by a passive region up to a certain potential; the passive current suddenly rises steeply without any sign of oxygen evolution. This denotes the breakdown of the passive film and initiation of pitting corrosion. It was found that the breakdown potential depends on the sulphate concentration, type of aeration, scan rate, solution temperature and pH. The pitting initiation may be explained through the adsorption of SO42– anion on the oxide film formed. This decreases the repair efficiency and causes further metal dissolution. From the cyclic voltammogram of zinc in different concentrations of Na2SO4, it was found that the change in the integrated anodic charge, Δqa, which is taken as a measure of the extent of pitting, varies linearly with concentration of SO42– anion.
The development of JISC strategy on electronic collections
Authors: Brindley Lynne J.
Published: July 2002

This paper traces the development of JISC strategy for, and provision of, networked information services through the 1990s. The account has been structured in “eras”, and although each lasted only a few years it was arguably equivalent to a long period of history in such a fast moving field. The early era of the Computer Board and the Information Systems Committee (precursors of JISC) was characterised by experimentation, risk‐taking, and learning by doing. With the establishment of JISC (Joint Information Systems Committee) in 1993 we entered a second era, of consolidation of policy, expansion of service provision through new datasets and databases, and increasing take‐up by users. The third era benefited from the wider context set by the Follett Report and, from 1995, saw a flowering of related projects and developments creating the “electronic library”. JISC’s new five‐year strategy launched late in 1996 heralded a fourth era, to be led by the Committee for Electronic Information (CEI) which has now set about widening the scope of nationally provided electronic collections even further, and has begun to tackle a wide range of management and policy issues relating to a much more mature range of services. The paper concludes with some consideration of the issues to be faced in the next phase of provision.
“Modern” learning methods: rhetoric and reality
Authors: Sadler‐Smith Eugene , Down Simon , Lean Jonathan
Published: July 2002

The application of technology in both its “hard” (for example through computing technology) and “soft” (for example through instructional design ) forms has enhanced the range of training methods available to practitioners. Much rhetoric has surrounded the use of techniques such as distance learning and computer‐based learning methods. The study aimed to explore the attitudes of managers to these “modern” approaches and other more “traditional” methods. A questionnaire survey of over 200 managers in organisations of all sizes and from a range of sectors was conducted. The data suggest that distance learning is not widely used as it is perceived as less effective, whereas at‐job learning, as well as being widely used is also perceived as being the most effective method. An analysis in terms of firm size revealed more similarities than differences between larger and smaller firms. The theoretical and practical implications of the results are discussed.
The portfolio career: pushed or pulled to it?
Authors: Mallon Mary
Published: July 2002

This paper explores the debate on emerging career forms, focusing on the notion of portfolio working. It comments that while the language used about careers is changing, there is a dearth of empirical studies about career trends. This study focuses in depth on a group of ex‐public sector managers who have left organisational employment for independent working. Drawing inductively on the interviews with them, the paper seeks to explore how they account for this move. It concludes that there is more evidence of push from the organisation than the intrinsic pull of portfolio working. However, once involved in this way of working most people become more reconciled to it.
Effects of short‐ and long‐term preference for temporary work upon psychological outcomes
Authors: Krausz Moshe
Published: July 2002

The study examined differences between voluntary and involuntary Canadian (N = 224) temporary help employees (THEs). The hypotheses stated that compared to involuntary THEs, voluntary THEs, particularly those who see it as a long‐term employment arrangement, are more satisfied and involved and less stressed. Results supported most of the hypotheses. Long‐term THEs were higher in overall satisfaction and in two of three measures of facet satisfaction. They were also lower in role conflict and role ambiguity. Analyses rule out the possibility that the results merely express adaptation of attitudes to imposed employment realities. It was also found that involuntary THEs prefer long assignments with a single client‐company whereas voluntary THEs prefer the variety associated with short‐term assignments. Few male (21.5 per cent of the sample) and female differences in outcome measures were found. Implications for client companies, for human resource agencies, and for individual employees are suggested.
Success Attributions within and across Organizations
Authors: Gronhaug Kjell , Falkenberg J.S.
Published: July 2002

Managers and organizations need to understand their surrounding
environments to exhibit purposeful behaviour. Due to limited cognitive
capacity their rationality is limited as well. Attribution and
attributional research serves point of departure to capture how managers
and organizations make sense of their internal and external
environments, enabling them to act purposefully. Explores a set of
tentative hypotheses in a small scale study and demonstrates differences
in success attributions between managers and across managerial teams in
high‐ and low‐performing organizations. Highlights theoretical and
managerial implications.
Training, development, education and learning: different or the same?
Authors: Garavan Thomas N.
Published: July 2002

Attempts to discuss the concepts of training, development, education and learning with regard to employees in terms of their substantive differences. Discusses how these concepts have evolved historically within human resource management and development (HRM/D) literature. Provides an analysis of how alternative models of HRM/D may influence the meaning given to these concepts in an organizational context. Concludes that it is perhaps more appropriate to view training, development and education as an integrated whole with the concept of learning as the glue which holds them together.
Entrepreneurship among business graduates: does a major in entrepreneurship make a difference?
Authors: Kolvereid Lars , Moen Øystein
Published: July 2002

Entrepreneurship has become a widely taught subject in universities and business schools. However, only a very small number of studies have investigated the effect of entrepreneurship education. The present research compares the behaviour of business graduates with a major in entrepreneurship and graduates with other majors from a Norwegian business school. The results indicate that graduates with an entrepreneurship major are more likely to start new businesses and have stronger entrepreneurial intentions than other graduates.
Misplaced marketing Meanwhile, at the service desk: “Hello!Is anyone here?”
Authors: Rotfeld Herbert Jack
Published: July 2002

Discusses the problem of poor customer service. Asserts that the introduction of new technology into the system does not necessarily improve the process. The more common situation finds that the new technology is being misused in ways that mimic the failures of no‐tech services: toll‐free numbers create long waits and Web sites provide an advertising platform rather than a customer service platform. Asserts that new technology provides excellent marketing opportunities for customer service but are often misused.
The marketing strategies of universities in the United Kingdom
Authors: Naudé Pete , Ivy Jonathan
Published: July 2002

Universities in the UK are facing huge changes to their environment, in terms of both supply of funding and level of demand for their courses. One of the most dramatic recent changes has been the alteration in status of the former polytechnics to fully fledged universities. In order to find out how both old and new universities are responding to this rapidly changing environment, we sent questionnaires to a number of senior staff. Based on 131 responses (81 from old universities, 50 from new), we have been able to paint a picture of how marketing is undertaken in these two segments. We report on how these institutions perceive their marketing task, and also the extent to which these two traditionally different sectors agree on the role marketing plays in their sector. Our research clearly indicates these two groups of institutions have fundamentally different approaches to operationalising their marketing strategies.
Analyzing the competitive advantages and disadvantages of Germany with the TOWS Matrix ‐ an alternative to Porter’s Model
Authors: Weihrich Heinz
Published: July 2002

This article will describe a logical and efficient process of developing coherent national strategies in light of environmental forces that are present in the global market. It will then apply that process to the Federal Republic of Germany. The TOWS (threats, opportunities, weaknesses, strengths) Matrix will be used to accomplish this task. The TOWS methodology will focus on aspects of German industries that have had a significant impact ‐ either positively or negatively ‐ on the country’s economy and its position in the European Community and the world. Intrinsic national forces in the social, economic, political, and technological areas will be considered in determining the origin of Germany’s national industrial strengths and weaknesses. External opportunities for and threats to these industries will then be analyzed. After an analysis of a wide array of forces, strategies by German industries will be delineated and alternative industrial strategies will be proposed. Because former West Germany differs very much from former East Germany, the analysis will focus on what used to be called “West Germany”, referred to in this paper simply as Germany.
Assessment of the quality of ladies’ garment fabrics – a preliminary report
Authors: Inoue T. , Niwa M. , Yamashita Y. , Minamide Y. , Inoue D. , Ishikawa A. , Kawabata S.
Published: July 2002

In order to establish an objective method of evaluating ladies’ garment fabrics by connecting the mechanical properties of ladies’ garment fabrics to subjective evaluation, subjective assessments were examined by judges who work at textile mills or in the textile trade. We examined a method of deriving objective equations, a total hand value (THV) equation and a total appearance value (TAV) equation. The THV equation was derived directly from the mechanical properties of the fabrics and the TAV equation was derived from three mechanical parameters which are related to the beauty of garment appearance. In the case of the THV objective equation, the accuracy of regression was high within the same groups of judges; however, in the case of the TAV objective equation, accuracy was slightly low. Because there were few subjects and that caused deviation, the accuracy of prediction was slightly low; however, the objective evaluation was adequate.
Influence of washing/ironing cycles on selected properties of cotton type weaves
Authors: Militky Jiˇrí , Bajzík Vladimír
Published: July 2002

Describes an experiment designed to investigate the influence of washing/ironing cycles and softening after sanforization on the hand grade, shrinkage and surface roughness of three selected cotton weaves for men’s shirts. Constructs the ANOVA type models with or without interactions, on the basis of the experimental results.
Communications
Authors: Koh Thong‐Hwee , Lee Eng‐Wah , Lee Yong‐Tsui
Published: July 2002

Apparel pattern making creates a set of pattern pieces of fabric which are sewn into the desired garment. The pattern pieces are developed through fashion analysis, pattern design and pattern drafting. Seeks to build an object‐oriented model of the apparel pattern‐making process through these subprocesses. Defines the model in terms of a requirements specification and subsequently uses it in the development of a computerized pattern‐making system. Uses object behaviour analysis, which is derived from object‐oriented technology, as the method for defining the model.
An investigation of the structure of sizing systems
Authors: Ashdown Susan P.
Published: July 2002

Most apparel sizing systems are based on one or two body dimensions and rely on assumptions about proportional body relationships to project other dimensions necessary to design the garment pattern. Garments from these systems will not fit a population with large variations in body proportions. Using nonlinear optimization methods and anthropometric data of US Army women three multidimensional sizing systems were derived that are designed to provide improved fit for women from the USA, a population with much variation. These systems range from an optimized linear system with a regular grade to an unconstrained optimized system with a grade break at each size. The optimized sizing systems compare favorably with D5585‐94 in their ability to accommodate variation in the population based on a mathematical test of the aggregate loss of each system. Issues related to pattern grading, size selection, and calculation of stock keeping units are discussed.
Air permeability and light transmission of weaves
Authors: Militky Jiri , Travnickova Marie , Bajzik Vladimir
Published: July 2002

The main aim of this contribution is characterization of fabric porosity by the light transmission and comparison of this characteristic with air permeability and idealized geometrical structure of selected weaves. For characterization of air permeability the classical apparatus has been used. The transmission of light through fabrics has been measured on the system LUCIA for image analysis. The porosity of textiles has been evaluated from corresponding construction parameters and idealized models of fabric geometry. The dependencies between the above mentioned characteristics were formalized by using regression analysis.
Thermophysiological comfort of silicone softeners‐treated woven textile materials
Authors: Tzanov Tzanro , Betcheva Rossitza , Hardalov Ivan
Published: July 2002

In this study the effect of the aminofunctional silicone softeners on fabrics’ heat and moisture transport properties has been investigated by means of Alambeta and Permetest instruments. The silicone treated PES blended fabrics are warmer to the touch, but less comfortable as regards their reduced water‐vapour permeability. The finishing stage of the fabrics has considerable influence on their thermal touch sensation and water‐vapour permeability.
Strategic leadership, resource management and effective school reform
Authors: Caldwell Brian J.
Published: July 2002

This paper is concerned with the impact of school reform on the professional culture of the principalship, drawing on findings from several research projects from 1993 to 1998. The focus is the schools of the future reform in Victoria, Australia. Despite several dysfunctions, some unfulfilled expectations and intensification of work, a large majority of principals would not wish to return to previous arrangements. Case studies reveal that principals play an important role in helping to link the structural aspects of reform to learning and teaching. Leadership is strategic and empowering more than it is heroic or “hands on”.
Momentum and heat transfer in visco‐elastic fluid flow in a porous medium over a non‐isothermal stretching sheet
Authors: Prasad K.V. , Subhas Abel M. , Khan Sujit Kumar
Published: July 2002

Visco‐elastic fluid flow and heat transfer in a porous medium over a non‐isothermal stretching sheet have been investigated. The flow is influenced by linearly stretching the sheet in the presence of suction, blowing and impermeability of the wall. Thermal conductivity is considered to vary linearly with temperature. The intricate non‐linear problem has been solved numerically by shooting technique with fourth order Runge‐Kutta algorithm after using perturbation method. The zeroth order solutions are obtained analytically in the form of Kummer’s function. An analysis has been carried out for two different cases, namely prescribed surface temperature (PST) and prescribed heat flux (PHF) to get the effect of porosity and visco‐elasticity at various physical situations. The important finding is that the effect of visco‐elasticity and porosity is to increase the wall temperature in case of blowing and to decrease in both the cases of suction and when the stretching sheet is impermeable.
Integral transforms in the two‐dimensional non‐linear formulation of longitudinal fins with variable profile
Authors: Cotta R.M. , Ramos R.
Published: July 2002

The integral transform method is employed for the hybrid numerical‐analytical solution of two‐dimensional, steady‐state heat conduction within extended surfaces of variable longitudinal profile and temperature dependent thermal conductivity. Numerical results are then obtainable with automatic accuracy, allowing for the establishment of benchmark results and for the validation of approximate solutions. Convergence rates are illustrated for longitudinal fins with trapezoidal and parabolic profiles, and for different values of the governing parameters, Biot number and aspect ratio. In addition, the classical one‐dimensional approximate solutions are critically examined for these typical non‐straight profiles, and the applicability limits are investigated.
Policies, procedures and standards
Authors: Moule Barry , Giavara Lina
Published: July 2002

Describes, through practical recent experiences, an approach to
implementing policies, standards and procedures in a large commercial
enterprise. Presents an outline of a guide for those considering the
long haul associated with such a major undertaking.
Employee empowerment in construction: an implementation model for process improvement
Authors: Holt Gary D. , Love Peter E.D. , Jawahar Nesan L.
Published: July 2002

The business environment of construction organisations has undergone significant change over the last 50 years. As a result, construction management has had to respond to issues such as increasing levels of client expectation, globalisation of the construction economy, cut‐throat competition, and tight margins, plus the “inherent” obstacles to operating in the sector, such as separation of design and construction, fragmented production methods, adversarial relationships, and a reluctance to innovate and take up information technology. Furthermore, the problems of poor and unstructured training, multi‐tiered management systems, and poor communication provide less than optimal conditions for achieving high quality products in good time and to budget. One approach to addressing these issues is through the concept of employee empowerment. This paper presents an overview of the empowerment concept in the context of construction management, highlighting the hurdles, an implementation process, and achievable benefits.
Some thermodynamic implications for the thermostability of proteins
Authors: Rees Douglas C. , Robertson Andrew D.
Published: July 2002

An analysis of the thermodynamics of protein stability reveals a general tendency for proteins that denature at higher temperatures to have greater free energies of maximal stability. To a reasonable approximation, the temperature of maximal stability for the set of globular, water‐soluble proteins surveyed by Robertson and Murphy occurs at T* ∼283K, independent of the heat denaturation temperature, Tm. This observation indicates, at least for these proteins, that thermostability tends to be achieved through elevation of the stability curve rather than by broadening or through a horizontal shift to higher temperatures. The relationship between the free energy of maximal stability and the temperature of heat denaturation is such that an increase in maximal stability of ∼0.008 kJ/mole/residue is, on average, associated with a 1°C increase in Tm. An estimate of the energetic consequences of thermal expansion suggests that these effects may contribute significantly to the destabilization of the native state of proteins with increasing temperature.
The Second Fundamental Theorem of Asset Pricing
Authors: Jarrow Robert A. , Jin Xing , Madan Dilip B.
Published: July 2002

This paper presents a resolution of the paradox proposed by the example of an economy with complette markets and a multiplicityof martingale measures constructed by Artzner and Heath (1995). The resolution lies in noting that completeness is with respect to a topology on the space of cash flows and is connected with uniqueness of the price functional in the topological dual space. Uniqueness may be lost outside the dual and this is what occurs in the counterexample of Artzner and Heath.
Human muscle sympathetic nerve activity and plasma noradrenaline kinetics in space
Authors: Ertl Andrew C. , Diedrich André , Biaggioni Italo , Levine Benjamin D. , Robertson Rose Marie , Cox James F. , Zuckerman Julie H. , Pawelczyk James A. , Ray Chester A. , Buckey Jay C. , Lane Lynda D. , Shiavi Richard , Gaffney F. Andrew , Costa Fernando , Holt Carol , Blomqvist C. Gunnar , Eckberg Dwain L. , Baisch Friedhelm J. , Robertson David
Published: July 2002

Astronauts returning from space have reduced red blood cell masses, hypovolaemia and orthostatic intolerance, marked by greater cardio–acceleration during standing than before spaceflight, and in some, orthostatic hypotension and presyncope. Adaptation of the sympathetic nervous system occurring during spaceflight may be responsible for these postflight alterations. We tested the hypotheses that exposure to microgravity reduces sympathetic neural outflow and impairs sympathetic neural responses to orthostatic stress. We measured heart rate, photoplethysmographic finger arterial pressure, peroneal nerve muscle sympathetic activity and plasma noradrenaline spillover and clearance, in male astronauts before, during (flight day 12 or 13) and after the 16 day Neurolab space shuttle mission. Measurements were made during supine rest and orthostatic stress, as simulated on Earth and in space by 7 min periods of 15 and 30 mmHg lower body suction. Mean (±s.e.m.) heart rates before lower body suction were similar pre–flight and in flight. Heart rate responses to −30 mmHg were greater in flight (from 56 ± 4 to 72 ± 4 beats min−1) than pre–flight (from 56 ± 4 at rest to 62 ± 4 beats min−1, P < 0.05). Noradrenaline spillover and clearance were increased from pre–flight levels during baseline periods and during lower body suction, both in flight (n= 3) and on post–flight days 1 or 2 (n= 5, P < 0.05). In–flight baseline sympathetic nerve activity was increased above pre–flight levels (by 10–33 %) in the same three subjects in whom noradrenaline spillover and clearance were increased. The sympathetic response to 30 mmHg lower body suction was at pre–flight levels or higher in each subject (35 pre–flight vs. 40 bursts min−1 in flight). No astronaut experienced presyncope during lower body suction in space (or during upright tilt following the Neurolab mission). We conclude that in space, baseline sympathetic neural outflow is increased moderately and sympathetic responses to lower body suction are exaggerated. Therefore, notwithstanding hypovolaemia, astronauts respond normally to simulated orthostatic stress and are able to maintain their arterial pressures at normal levels.
Life‐long impairment of hypoxic phrenic responses in rats following 1 month of developmental hyperoxia
Authors: Fuller D. D. , Bavis R. W. , Vidruk E. H. , Wang Z.‐Y. , Jr Olson E. B. , Bisgard G. E. , Mitchell G. S.
Published: July 2002

Hypoxic ventilatory and phrenic responses are reduced in adult rats (3–5 months old) exposed to hyperoxia for the first month of life (hyperoxia treated). We previously reported that hypoxic phrenic responses were normal in a small sample of 14‐ to 15‐month‐old hyperoxia‐treated rats, suggesting slow, spontaneous recovery. Subsequent attempts to identify the mechanism(s) underlying this spontaneous recovery of hypoxic phrenic responses led us to re‐evaluate our earlier conclusion. Experiments were conducted in two groups of aged Sprague‐Dawley rats (14–15 months old) which were anaesthetized, vagotomized, neuromuscularly blocked and ventilated: (1) a hyperoxia‐treated group raised in 60 % O2 for the first 28 postnatal days; and (2) an age‐matched control group raised in normoxia. Increases in minute phrenic activity and integrated phrenic nerve amplitude (∫Phr) during isocapnic hypoxia (arterial partial pressures of O2, 60, 50 and 40 ± 1 mmHg) were greater in aged control (n= 15) than hyperoxia‐treated rats (n= 11; P⩽ 0.01). Phrenic burst frequency during hypoxia was not different between groups. To examine the central integration of carotid chemoafferent inputs, steady‐state relationships between carotid sinus nerve (electrical) stimulation frequency and phrenic nerve activity were compared in aged control (n= 7) and hyperoxia‐treated rats (n= 7). Minute phrenic activity, ∫Phr and burst frequency were not different between groups at any stimulation frequency between 0.5 and 20 Hz. Carotid body chemoreceptor function was examined by recording whole carotid sinus nerve responses to cessation of ventilation or injection of cyanide in aged control and hyperoxia‐treated rats. Electrical activity of the carotid sinus nerve did not change in five out of five hyperoxia‐treated rats in response to stimuli that evoked robust increases in carotid sinus nerve activity in five out of five control rats. Estimates of carotid body volume were lower in aged hyperoxia‐treated rats (4.4 (± 0.2) × 106μm3) compared to controls (17.4 (± 1.6) × 106μm3; P <0.01). We conclude that exposure to hyperoxia for the first month of life causes life‐long impairment of carotid chemoreceptor function and, consequently, blunted phrenic responses to hypoxia.
Synaptic transmission in nucleus tractus solitarius is depressed by Group II and III but not Group I presynaptic metabotropic glutamate receptors in rats
Authors: Chen Chao‐Yin , Ling Erh‐hsin , Horowitz John M. , Bonham Ann C.
Published: July 2002

Presynaptic metabotropic glutamate receptors (mGluRs) serve as autoreceptors throughout the CNS to inhibit glutamate release and depress glutamatergic transmission. Both presynaptic and postsynaptic mGluRs have been implicated in shaping autonomic signal transmission in the nucleus tractus solitarius (NTS). We sought to test the hypothesis that activation of presynaptic mGluRs depresses neurotransmission between primary autonomic afferent fibres and second‐order NTS neurones. In second‐order NTS neurones, excitatory postsynaptic currents (EPSCs) synaptically evoked by stimulation of primary sensory afferent fibres in the tractus solitarius (ts) and currents postsynaptically evoked by α‐amino‐3‐hydroxy‐4‐isoxazoleproprionic acid (AMPA) were studied in the presence and absence of mGluR agonists and antagonists. Real‐time quantitative RT‐PCR (reverse transcription‐polymerase chain reaction) was used to determine whether the genes for the mGluR subtypes were expressed in the cell bodies of the primary autonomic afferent fibres. Agonist activation of Group II and III but not Group I mGluRs reduced the peak amplitude of synaptically (ts) evoked EPSCs in a concentration‐dependent manner while having no effect on postsynaptically (AMPA) evoked currents recorded in the same neurones. At the highest concentrations, the Group II agonist, (2S,3S,4S)‐CCG/(2S,1′S,2′S)‐2‐carboxycyclopropyl (l‐CCG‐I), decreased the amplitude of the ts‐evoked EPSCs by 39 % with an EC50of 21 μm, and the Group III agonist,l(+)‐2‐amino‐4‐phosphonobutyric acid (l‐AP4), decreased the evoked EPSCs by 71 % with an EC50of 1 mm. mRNA for all eight mGluR subtypes was detected in the autonomic afferent fibre cell bodies in the nodose and jugular ganglia. Group II and III antagonists ((2S,3S,4S)‐2‐methyl‐2‐(carboxycyclopropyl)glycine (MCCG) and (RS)‐α‐methylserine‐O‐phosphate (MSOP)), at concentrations that blocked the respective agonist‐induced synaptic depression, attenuated the frequency‐dependent synaptic depression associated with increasing frequencies of ts stimulation by 13–34 % and 13–19 %, respectively (P< 0.05, for each). We conclude that Group II and III mGluRs (synthesized in the cell bodies of the primary autonomic afferent fibres and transported to the central terminals in the NTS) contribute to the depression of autonomic signal transmission by attenuating presynaptic release of glutamate.
Effects of daily spontaneous running on the electrophysiological properties of hindlimb motoneurones in rats
Authors: Beaumont Eric , Gardiner Phillip
Published: July 2002

No evidence currently exists that motoneurone adaptations in electrophysiological properties can result from changes in the chronic level of neuromuscular activity. We examined, in anaesthetized (ketamine/xylazine) rats, the properties of motoneurones with axons in the tibial nerve, from rats performing daily spontaneous running exercise for 12 weeks in exercise wheels (‘runners’) and from rats confined to plastic cages (‘controls’). Motoneurones innervating the hindlimb via the tibial nerve were impaled with sharp glass microelectrodes, and the properties of resting membrane potential, spike threshold, rheobase, input resistance, and the amplitude and time‐course of the afterhyperpolarization (AHP) were measured. AHP half‐decay time was used to separate motoneurones into ‘fast’ (AHP half‐decay time < 20 ms) and ‘slow’ (AHP half‐decay time ≥ 20 ms), the proportions of which were not significantly different between controls (58 % fast) and runners (65 % fast). Two‐way ANOVA and ANCOVA revealed differences between motoneurones of runners and controls which were confined to the ‘slow’ motoneurones. Specifically, runners had slow motoneurones with more negative resting membrane potentials and spike thresholds, larger rheobasic spike amplitudes, and larger amplitude AHPs compared to slow motoneurones of controls. These adaptations were not evident in comparing fast motoneurones from runners and controls. This is the first demonstration that physiological modifications in neuromuscular activity can influence basic motoneurone biophysical properties. The results suggest that adaptations occur in the density, localization, and/or modulation of ionic membrane channels that control these properties. These changes might help offset the depolarization of spike threshold that occurs during rhythmic firing.
Nitric oxide inhibits capacitative Ca2+ entry and enhances endoplasmic reticulum Ca2+ uptake in bovine vascular endothelial cells
Authors: Dedkova Elena N. , Blatter Lothar A.
Published: July 2002

In vascular endothelial cells, elevation of cytosolic free calcium concentration ([Ca2+]i) causes activation of nitric oxide synthase (NOS) and release of nitric oxide (NO). The goal of the study was to characterize the interplay between [Ca2+]i and NO production in this cell type. Simultaneous measurements of [Ca2+]i and intracellular NO concentration ([NO]i) in cultured bovine vascular endothelial cells (CPAE cell line) with the fluorescent indicators fura‐2 and DAF‐2, respectively, revealed that Ca2+ influx following agonist‐induced intracellular Ca2+ store depletion (capacitative Ca2+ entry, CCE) represents the preferential Ca2+ source for the activation of the Ca2+‐calmodulin‐dependent endothelial NOS (eNOS). Exposure to the NO donor sodium nitroprusside (SNP) showed that high NO levels suppressed CCE and had an inhibitory effect on Ca2+ extrusion by the plasmalemmal Ca2+‐ATPase. This inhibitory effect on CCE was mimicked by the membrane‐permeant cGMP analogue 8‐bromo‐cGMP, but was reversed by the NO scavenger haemoglobin and prevented by the inhibitor of the NO‐sensitive guanylate cyclase ODQ. Brief exposure to SNP reduced the peak of ATP‐induced Ca2+ release from the endoplasmic reticulum (ER) and accelerated Ca2+ reuptake into the ER. Prolonged incubation with SNP resulted in enhanced Ca2+ loading of the ER, as revealed by direct measurements of store content with the ER‐entrapped low‐affinity Ca2+ indicator mag‐fura‐2. The results suggest that in vascular endothelial cells, NO synthesis is under autoregulatory control that involves NO‐dependent [Ca2+]i regulation. Via cGMP‐dependent inhibition of CCE and acceleration of Ca2+ sequestration into the ER, NO can lower [Ca2+]i and therefore exert an autoregulatory negative feedback on its own Ca2+‐dependent synthesis.
Asymptotic Analysis of the Stress Field in Adhering Dental Restorations
Authors: Hu¨bsch P. F. , Middleton J.
Published: July 2002

Polymer-based composites are widely used in restorative dentistry as alternatives to metals and ceramics to fill cavities in teeth. They adhere to the walls of the cavity in the tooth, thus forming a composite body consisting of dentine, enamel, and composite resin. Geometric discontinuities along the interfaces between these materials can induce singularities in the stress field, which in turn lead to premature failure of the restoration. In the present investigation, a complex stress function technique is employed to derive the order of the stress singularity. It is shown that the order of the singularity depends on both the material properties of the restorative material and the local geometry of the cavity. It is also shown that the singularity in the stress field can be avoided through careful design of the cavity shape. The results presented correlate well with experimental results reported in the literature. [S0148-0731(00)01504-1]
Observations of Slug Dissipation in Downward Flow
Authors: Zhang Hong-Quan , Redus Clifford L. , Brill James P. , Yuan Hong
Published: July 2002

Detailed observations were made for slug flow in an upward to downward pipeline configuration with 13 capacitance sensors. The results presented in this study are based on four typical tests, which demonstrate the phenomena encountered in slug dissipation. In downward flow, slug frequency decreases with different extent at different flow rates. There is a reduction of slug length after the turning over from upward to downward flow. However, the slug tends to recover its stable length in further downstream development, except for flow that quickly becomes stratified. Growth of the slug length is accomplished by picking up liquid left by the downstream dissipating slug before being fully absorbed by the liquid film. [S0195-0738(00)00503-3]
Microstructural Changes and Contact Temperatures During Fretting in Steel-Steel Contact
Authors: Podgornik B. , Kalin M. , Vizˇintin J. , Vodopivec F.
Published: July 2002

In fretting wear, the microstructure and the mechanical properties of the surface and subsurface layer depend significantly on the temperature field produced in the fretting zone. Information reported in the literature indicate contradictory values for the temperature produced at the interface under fretting conditions. In the present study, a successive grinding technique was used to examine the microstructural changes generated by fretting of AISI 52100 steel and the results were compared to the mathematically calculated contact temperatures using different models. Results of this investigation indicate that white layer starts to form under individual contact spots as a result of high flash temperatures and then over the test time it grows by coalescence to a single large area.
Natural Transition Phenomena on an Axial Compressor Blade
Authors: Hughes J. D. , Walker G. J.
Published: July 2002

Data from a surface hot-film array on the outlet stator of a 1.5-stage axial compressor are analyzed to look for direct evidence of natural transition phenomena. An algorithm is developed to identify instability waves within the Tollmien–Schlichting (T–S) frequency range. The algorithm is combined with a turbulent intermittency detection routine to produce space-time diagrams showing the probability of instability wave occurrence prior to regions of turbulent flow. The paper compares these plots for a range of blade loading, with free-stream conditions corresponding to the maximum and minimum inflow disturbance periodicity produced by inlet guide vane clocking. Extensive regions of amplifying instability waves are identified in nearly all cases. The implications for transition prediction in decelerating flow regions on axial turbomachine blades are discussed.
Experimental Assessment of Fiber-Reinforced Ceramics for Combustor Walls
Authors: Filsinger D. , Mu¨nz S. , Schulz A. , Wittig S. , Andrees G.
Published: July 2002

Experimental and theoretical work concerning the application of ceramic components in small high-temperature gas turbines has been performed for several years. The significance of some nonoxide ceramic materials for gas turbines in particular is based on their excellent high-temperature properties. The application of ceramic materials allows an increase of the turbine inlet temperature resulting in higher efficiencies and a reduction of pollution emissions. The inherent brittleness of monolithic ceramic materials can be virtually reduced by reinforcement with ceramic fibers leading to a quasiductile behavior. Unfortunately, some problems arise due to oxidation of these composite materials in the presence of hot gas flow containing oxygen. At the Motoren und Turbinen Union, Mu¨nchen GmbH, comprehensive investigations including strength, oxidation, and thermal shock tests of several materials that seemed to be appropriate for combustor liner applications were undertaken. As a result, C/C, SiC/SiC, and two C/SiC composites coated with SiC, as oxidation protection, were chosen for examination in a gas turbine combustion chamber. To prove the suitability of these materials under real engine conditions, the fiber-reinforced flame tubes were installed in a small gas turbine operating under varying conditions. The loading of the flame tubes was characterized by wall temperature measurements. The materials showed different oxidation behavior when exposed to the hot gas flow. Inspection of the C/SiC composites revealed debonding of the coatings. The C/C and SiC/SiC materials withstood the tests with a maximum cumulated test duration of 90 h without damage.
Kinematics-Based Determination of the Rolling Region in Roll Bending for Smoothly Curved Plates
Authors: Shin Jong Gye , Park Joon Tae , Yim Hyunjune
Published: July 2002

This paper proposes and develops a kinematics-based, systematic approach to determine the region of a plate to be rolled, in order to fabricate smoothly curved plates. The approach includes a kinematic analysis to calculate the plate’s curvature distribution, and, in addition, a linear regression analysis to determine the initial and final locations of the roller during the roll bending process. Three artificial cases and two real cases have been studied, and the results are in good agreement with field practices. This approach will play an important role in the automation and optimization of the plate forming process.
Flow Filling a Curved Pipe
Authors: Michallet H. , Mathis C. , Mai¨ssa P. , Dias F.
Published: July 2002

A small scale experiment was designed to study the propagation of the front of a viscous fluid filling a curved pipe. Several Newtonian fluids with different viscosities and a non-Newtonian fluid have been used. The experiments show that there exists a minimum speed for completely filling the pipe, which depends on the parameters of the experiment (diameter d and radius of curvature R of the pipe, kinematic viscosity ν of the fluid). Appropriate dimensionless numbers are introduced to characterize the flow and optimal filling conditions.
Exact Evaluation of Natural Frequency and Damping Ratio from a Frequency Response Curve
Authors: Drexel M. V. , Ginsberg J. H.
Published: July 2002

Several experimental modal analysis techniques fit resonance peaks to the response curves of a single degree of freedom system in order to identify the natural frequencies and modal damping ratios. The present study identifies a fundamental property of frequency response curves that allows the natural frequency to be identified from a simple characteristic of the curve, independently of the damping ratio. After the natural frequency has been determined, the damping ratio can be computed directly. The fundamental property holds for all values of damping, which eliminates the need to approximate either the natural frequency or damping ratio.
On a General Method of Unsteady Potential Calculation Applied to the Compression Stages of a Turbomachine—Part II: Experimental Comparison
Authors: Kouidri S. , Belamri T. , Bakir F. , Rey R.
Published: July 2002

Several applications were carried out in order to validate the method presented in Part I. In Part II, two examples of these applications are presented; one relating to the aeroacoustics of the axial fans and the other one to the interaction impeller-volute tongue in a centrifugal pump. The test benches used to study the behavior of these machines are presented. The study of the fan was capable of quantifying the discrete noise associated with the fluctuations in pressure linked to the potential flow. The analysis of the centrifugal pump permitted comparing the theoretical pressure fluctuations with experimental ones measured by various unsteady pressure sensors placed on the impeller shroud and in the volute. The qualitative and quantitative results obtained confirm the interest and the range of the developed algorithm.