bluuebunny/crossref_metadata_2025 huggingface dataset:
Volatile Anesthetics Enhance Flash-induced γ Oscillations in Rat Visual Cortex
Authors: Imas Olga A. , Ropella Kristina M. , Ward B Douglas , Wood James D. , Hudetz Anthony G.
Published: April 2005

Background

The authors sought to understand neural correlates of anesthetic-induced unconsciousness. Cortical gamma oscillations have been associated with neural processes supporting conscious perception, but the effect of general anesthesia on these oscillations is controversial. In this study, the authors examined three volatile anesthetics, halothane, isoflurane, and desflurane, and compared their effects on flash-induced gamma oscillations in terms of equivalent concentrations producing the loss of righting reflex (1 minimum alveolar concentration for the loss of righting [MAC(LR)]).

Methods

Light flashes were presented every 5 s for 5 min, and event-related potentials were recorded from primary visual cortex of 15 rats with a chronically implanted bipolar electrode at increasing anesthetic concentrations (0-2.4 MAC(LR)). Early cortical response was obtained by averaging poststimulus (0-100 ms) potentials filtered at 20-60 Hz across 60 trials. Late (100-1,000 ms) gamma power was calculated using multitaper power spectral technique. Wavelet decomposition was used to determine spectral and temporal distributions of gamma power.

Results

The authors found that (1) halothane, isoflurane, and desflurane enhanced the flash-evoked early cortical response in a concentration-dependent manner; (2) the effective concentration for this enhancement was the lowest for isoflurane, intermediate for halothane, and the highest for desflurane when compared at equal fractions of the concentration that led to a loss of righting; (3) the power of flash-induced late (> 100 ms) gamma oscillations was augmented at intermediate concentrations of all three anesthetic agents; and (4) flash-induced gamma power was not reduced below waking baseline even in deep anesthesia.

Conclusions

These findings suggest that a reduction in flash-induced gamma oscillations in rat visual cortex is not a unitary correlate of anesthetic-induced unconsciousness.
Selective Thromboxane A2Synthase Inhibition by OKY-046 Prevents Cardiopulmonary Dysfunction after Ovine Smoke Inhalation Injury
Authors: Westphal Martin , Noshima Shinji , Isago Tsukasa , Fujioka Kentarou , Maybauer Marc O. , Maybauer Dirk M. , Traber Lillian D. , Flynn John T. , Westphal-Varghese Beena B. , Traber Daniel L.
Published: April 2005

Background

Because thromboxane A2 is implicated in the pathophysiology of acute lung injury, the aim of this study was to evaluate the effects of selective thromboxane A2 synthase inhibition on cardiopulmonary function in the experimental setting of severe smoke inhalation injury.

Methods

Sixteen adult sheep were operatively instrumented for chronic study. The injured intervention group was treated with the selective thromboxane A2 synthase inhibitor OKY-046, whereas the injured control group received only the vehicle (n = 8 each).

Results

The progressive increase in thromboxane B2 lung lymph concentrations in control animals was associated with increased transvascular fluid flux, augmented resistances in the pulmonary and systemic circulation, and a reciprocal decrease in cardiac output. In addition, end-systolic pressure-diameter relation and maximum +dp/dt were markedly depressed as compared with baseline (24 h: 14.3 +/- 0.9 vs. 8.9 +/- 0.5 mmHg/mm and 2,120 +/- 50 vs. 1,915 +/- 40 mmHg/s, respectively; each P < 0.05). Infusion of OKY-046 significantly inhibited pulmonary thromboxane B2 delivery, attenuated the early increase in pulmonary vascular resistance, and blocked the increase in systemic vascular resistance. In addition, OKY-046 blunted and delayed the decrease in cardiac output and maintained end-systolic pressure-diameter relation, +dp/dt, and lung lymph flow at baseline values.

Conclusions

These findings suggest that selective thromboxane A2 synthase inhibition may represent a goal-directed therapeutic approach to alleviate cardiovascular and pulmonary dysfunction in the setting of smoke inhalation injury.
Intravenous Lidocaine Relieves Spinal Cord Injury Pain
Authors: Finnerup Nanna B. , Biering-Sørensen Fin , Johannesen Inger L. , Terkelsen Astrid J. , Juhl Gitte I. , Kristensen Anders D. , Sindrup Søren H. , Bach Flemming W. , Jensen Troels S.
Published: April 2005

Background

Neuropathic pain in spinal cord injury is a common challenging therapeutic condition. The current study examines the analgesic effect of the sodium channel blocker lidocaine on neuropathic pain in patients with spinal cord injury and the predictive role of concomitant evoked pain on pain relief with lidocaine.

Methods

Twenty-four spinal cord injury patients with neuropathic pain at or below the level of injury were randomized and completed a double-blind crossover trial of 5 mg/kg lidocaine and placebo infused over 30 min. Twelve patients reported evoked pain, and 12 patients had no evoked pain. Spontaneous and evoked pains were assessed using a visual analog scale and quantitative sensory testing.

Results

Lidocaine significantly reduced spontaneous pain in all patients (P < 0.01) and in each of the two groups with (P < 0.01) and without (P = 0.048) evoked pain, with no difference in number of responders (pain reduction > or = 33%) between the patients with (n = 6) and without (n = 5) evoked pain. Lidocaine significantly relieved both at-level and below-level neuropathic pain and decreased brush-evoked dysesthesia but not cold allodynia, pinprick hyperalgesia, or pain evoked by repetitive pinprick.

Conclusions

Lidocaine reduced neuropathic pain at and below the level of injury irrespective of the presence or absence of evoked pain. Results are consistent with a central-acting effect of sodium channel blockers acting on neuronal hyperexcitability. Agents (such as anticonvulsants or antiarrhythmics) with sodium channel-blocking properties may be a treatment option for spinal cord injury pain.
3D model‐based free‐form object recognition – a review
Authors: Saeed Mian Ajmal , Bennamoun Mohammed , Owens Robyn
Published: April 2005

Purpose

In model‐based recognition the 3D models of objects are stored in a model library during an offline phase. During the online recognition phase, a view of the scene is matched with the model library to identify the location and pose of certain library objects in the scene. Aims to focus on the process of 3D modeling and model‐based recognition.

Design/methodology/approach

This paper discusses the process of 3D modeling and model‐based recognition along with their potential applications in industry with a particular emphasis on robot grasp analysis. The paper also emphasises the main challenges in these areas and give a brief literature review.

Findings

In order to develop an automatic 3D model‐based object recognition system it is necessary to automate the process of 3D modeling and recognition. The challenge in automating the 3D modeling process is to develop an automatic correspondence technique. The core of recognition is the representation scheme. Recognition is an online process. Therefore, representation and matching must be very fast in order to facilitate real time recognition.

Practical implications

There are numerous applications of 3D modeling in a variety of areas ranging from the entertainment industry to industrial automation. Some of its applications include computer graphics, virtual reality, medical imaging, reverse engineering, and 3D terrain construction.

Originality/value

Provides information on 3D modeling which constitutes an important part of computer vision or robot vision.
Knowledge management for sustainable competitiveness in small and medium surveying practices
Authors: Egbu Charles O. , Hari Subashini , Renukappa Suresh H.
Published: April 2005

Purpose

An investigation of the importance of the knowledge of the key individuals in organisations, knowledge within organisations as well as customer capital and knowledge; and how these might impact on sustainable competitive advantage of small and medium sized enterprises. The key challenges for knowledge‐intensive SMEs are the identification, capture, storing, mapping, dissemination and creation of knowledge from different perspectives and for different purposes.

Design/methodology/approach

Based on a thorough review of literature and field study, this paper presents and discusses the benefits of knowledge management (KM) for sustainable competitiveness in SMEs in surveying practices. A field study was conducted, involving 12 professionals from eleven organisations, of which 2 of the 11 organisations were surveying practices.

Findings

The paper highlights the role of strategies, tools and techniques which might be of assistance. The paper concludes that managing knowledge assets in SME is not easy. It is an integrated and complex social process, which has culture, people, finance, technology and organisational structures at its core. The paper also notes that SMEs can benefit from effective KM practices for sustainable competitiveness.

Research limitations/implications

Recommendations are offered to surveying practices that are already involved with formal KM initiatives and those SMEs that aspire to do so.

Originality/value

An innovative study applying knowledge management principles to small and medium sized surveying practices.
Factors affecting construction labour productivity for Malaysian residential projects
Authors: Abdul Kadir M.R. , Lee W.P. , Jaafar M.S. , Sapuan S.M. , Ali A.A.A.
Published: April 2005

Purpose

Construction labour productivity is of great interest to practitioners and researchers because it affects project cost and time overrun. This paper evaluates and ranks the importance, frequency and severity of project delay factors that affect the construction labour productivity for Malaysian residential projects.

Design/methodology/approach

A total of 100 respondents consisting of 70 contractors, 11 developers and 19 consultants participated in this study. The respondents were asked to indicate how important each item of a list of 50 project related factors was to construction labour productivity. The data were then subjected to the calculation of importat indices which enabled the factors to be ranked.

Findings

The five most important factors identified by them were: material shortage at site; non‐payment to suppliers causing the stoppage of material delivery to site; change order by consultants; late issuance of construction drawing by consultants; and incapability of contractors' site management to organise site activities. On the other hand, the five most frequent factors were: material shortage at project site; non‐payment to suppliers causing the stoppage of material delivery to site; late issuance of progress payment by the client to main contractor; lack of foreign and local workers in the market; and coordination problem between the main contractor and subcontractor.

Originality/value

The inferences drawn from this study could be used by the project managers to take account of these factors at an early stage, hence minimising the time and cost overrun.
Implementation of strategies in continuing education
Authors: Kettunen Juha
Published: April 2005

Purpose

The purpose of this paper is to provide higher education institutions with strategies of continuing education and methods to communicate and implement these strategies.

Design/methodology/approach

The balanced scorecard approach is used to implement the strategy. It translates the strategy into tangible objectives, measures and targets and balances them into four different perspectives: customer, finance, internal processes, and learning.

Findings

The strategy of focus combined with the strategy of cost‐efficiency is applicable for higher education institutions. These strategies can be adjusted, for example, to profitable growth in continuing education.

Research limitations/implications

The balanced scorecard approach can be used widely in higher education institutions and with slight modifications in other public sector organisations. The customer perspective typically includes the desired objectives in the public sector, contrary to the private sector where it is reasonable to place finance at the top of the perspectives.

Practical implications

The study also presents a useful example of how the strategy can be described using the concept of a strategy map and numerical balanced scorecards.

Originality/value

It turns out that the strategies of focus and cost‐effectiveness and the balanced scorecard approach, developed in the business literature, can be successfully applied in continuing education.
Performance management in the UK public sector
Authors: McAdam Rodney , Hazlett Shirley‐Ann , Casey Christine
Published: April 2005

Purpose

The aim of this paper is to explore the issues involved in developing and applying performance management approaches within a large UK public sector department using a multiple stakeholder perspective and an accompanying theoretical framework.

Design/methodology/approach

An initial short questionnaire was used to determine perceptions about the implementation and effectiveness of the new performance management system across the organisation. In total, 700 questionnaires were distributed. Running concurrently with an ethnographic approach, and informed by the questionnaire responses, was a series of semi‐structured interviews and focus groups.

Findings

Staff at all levels had an understanding of the new system and perceived it as being beneficial. However, there were concerns that the approach was not continuously managed throughout the year and was in danger of becoming an annual event, rather than an ongoing process. Furthermore, the change process seemed to have advanced without corresponding changes to appraisal and reward and recognition systems. Thus, the business objectives were not aligned with motivating factors within the organisation.

Research limitations/implications

Additional research to test the validity and usefulness of the theoretical model, as discussed in this paper, would be beneficial.

Practical implications

The strategic integration of the stakeholder performance measures and scorecards was found to be essential to producing an overall stakeholder‐driven strategy within the case study organisation.

Originality/value

This paper discusses in detail the approach adopted and the progress made by one large UK public sector organisation, as it attempts to develop better relationships with all of its stakeholders and hence improve its performance. This paper provides a concerted attempt to link theory with practice.
The value of online surveys
Authors: Evans Joel R. , Mathur Anil
Published: April 2005

Purpose

To provide a thorough analysis of the role of the internet in survey research and to discuss the implications of online surveys becoming such a major force in research.

Design/methodology/approach

The paper is divided into four major sections: an analysis of the strengths and potential weaknesses of online surveys; a comparison of online surveys with other survey formats; a discussion on the best uses for online surveys and how their potential weaknesses may be moderated; and an overview of the online survey services being offered by the world's largest research firms.

Findings

If conducted properly, online surveys have significant advantages over other formats. However, it is imperative that the potential weaknesses of online surveys be mitigated and that online surveys only be used when appropriate. Outsourcing of online survey functions is growing in popularity.

Practical implications

The paper provides a very useful source of information and impartial advice for any professional who is considering the use of online surveys.

Originality/value

The paper synthesizes the vast literature related to online surveys, presents original material related to survey methodology, and offers a number of recommendations.
Turbidity generation and biological impacts of an exotic fish Carassius auratus, introduced into shallow seasonally anoxic ponds
Authors: Richardson M. J. , Whoriskey F. G. , Roy L. H.
Published: April 2005

Over the last decade, goldfish Carassius auratus L., have been introduced into lakes and ponds in the Montreal region. Controlled experiments compared the impact of goldfish in both mud‐and gravel‐bottomed outdoor pools, with either caged or non‐caged vegetation. High levels of turbidity were generated by foraging goldfish in mud pools (P<0.01). All non‐caged submersed plants (Potamogeton) showed extensive grazing damage and all of the unprotected submersed and emergent forms were uprooted. Data from Stoneycroft pond where a feral goldfish population reached 15–17 000 individuals ha‐1, confirmed the experimental findings showing goldfish to be benthic herbivores, causing a visible increase in turbidity and decrease in aquatic vegetation. Gut analysis revealed goldfish to have little diet overlap with native amphibians. High turbidity should reduce the success of predators feeding on goldfish, and may decrease the foraging success of other competitors. The sporadic distribution of goldfish in Canada may be linked to site characteristics, specifically the susceptibility of the area to turbidity generation.
Temperature‐ and developmentally‐induced variation in the histochemical profile of myofibrillar ATPase activity in carp
Authors: Nathanailides C. , Lopez‐Albors O. , Stickland N. C.
Published: April 2005

The histochemical profile of calcium activated acid stable myofibrillar ATPase (mATPase) activity in developing larval and juvenile carp was investigated. In the larval fish, differentiation of pink muscle fibres occurred after metamorphosis which was delayed by a week at 17° C compared to larvae grown at 27° C. After metamorphosis the 27° C group exhibited some small myofibres with acid stable mATPase activity in the deep white muscle. This was similar for the juvenile carp which were acclimated for more than a month at 25° C. In contrast, the cold (12° C) acclimated juvenile fish, contained very few small white muscle fibres with acid stable mATPase activity. It was also noted that the cold acclimated fish had lower background acid stable mATPase activity than the warm acclimated fish. Results indicate that after metamorphosis and more evidently in juveniles, temperature can influence the rate of myofibre hyperplasia.
A surface‐dependent gastric evacuation model for fish
Authors: Salvanes A. G. V. , Aksnes D. L. , Giske J.
Published: April 2005

A gastric evacuation curve expresses how fast prey disappear from the stomach, and empirical models are used generally for the relationship between weight of prey remaining (Wt) and time (t) after a meal. Unfortunately, empirical models are likely to have restricted applicability because their parameters often represent limited biological mechanisms. This paper develops a simple digestion model. The simplest form of the model has four parameters; the digestion velocity (expressing enzymatic breakdown of prey), prey length, initial prey radius and the density of the prey. Two more parameters are included in an extended version; a time‐delay before digestion starts and environmental temperature. The approach is based on the assumption that prey digestion is a surface process in that digestive enzymes attack progressively deeper into a prey of known size and shape so that the average digestion rate is proportional to the prey radius r (m). This process is characterized by the digestion velocity ds (m s –1). Unknown parameters are estimated with uncertainty using the maximum likelihood technique. Model evaluation using published data sets demonstrated that the new model is flexible. Prey geometry is incorporated into the model and temperature effects upon gastric evacuation are linked directly to the digestion velocity.
Structures of High‐Temperature Cuprate Superconductors
Authors: Park Chan , Snyder Robert L.
Published: April 2005

Most of the known cuprate superconductors are shown to belong structurally to a single family and are closely related to each other. The relationships between the structures of cuprate superconductors are reviewed with emphasis on their similarities. Individual details of the structures are ignored and only idealized structures are discussed. A formula is used to describe the basic structures of the cuprate superconductors. Crystal structure analysis leads to three significant insights into the nature of, and requirements for, superconductivity in these phases: (1) A nearly planar sheet of CuO2 supports the supercurrent. (2) As the distance between the n ACuO2 blocks in a crystal structure increases, the critical current density decreases at high reduced temperatures due to the magnetic flux lines becoming unpinned. (3) The strain energy generated by the lattice mismatch between the CuO2 layers and the nonsupercon‐ ducting layers controls the oxidation state of the Cu ions, which needs to be about +2.2 (in p‐type superconductors) to get Cooper pair condensation.
Interfacial Debonding Behavior of Mullite/SiC Continuous Fiber Composite
Authors: Yamade Yoshiaki , Kawaguchi Yoshiaki , Takeda Nobuo , Kishi Teruo
Published: April 2005

Mullite/SiC continuous fiber composites were fabricated by hot‐pressing under different processing conditions. The interfacial shear strength was measured during the pull‐out test, and the effect of fabrication conditions on interfacial debonding behavior was discussed. The debonding length during the pull‐out test was quantitatively evaluated using acoustic emission. The interfacial shear strength was evaluated by stress analysis. The control of interfacial shear strength was achieved by controlling the hot‐press temperature. An increase of load was found during the pull‐out process after complete debonding. In order to explain the increased load, a new model is presented.
Reaction Sintering of ZnO‐AI2O3
Authors: Hong Wan‐Shick , De Jonghe Lutgard C. , Yang Xi , Rahaman Mohamed N.
Published: April 2005

The reaction sintering of equimolar mixtures of ZnO and A12O3 powders was investigated as a function of primary processing parameters such as the temperature, heating rate, green density, and particle size. The powder mixtures were prepared by two different methods. In one method, the ZnO and A12O3 powders were ball‐milled. In the other method, the ZnO powder was chemically precipitated onto the A12O3 particles dispersed in a solution of zinc chloride. The sintering characteristics of the compacted powders prepared by each method were compared with those for a prereacted, single‐phase powder of zinc aluminate, ZnAl2O4. The chemical reaction between ZnO and A12O3 occurred prior to densification of the powder compact and was accompanied by fairly large expansion. The mixing procedure had a significant effect on the densification rate during reaction sintering. The densification rate of the compact formed from the ball‐milled powder was strongly inhibited compared to that for the single‐phase ZnAl2O4 powder. However, the densification rate of the compact formed from the chemically precipitated mixture was almost identical to that for the ZnAl2O4 powder. The difference in sintering between the ball‐milled mixture and the chemically precipitated mixture is interpreted in terms of differences in the microstructural uniformity of the initial powder compacts resulting from the different preparation procedures.
Phase Diagram for Mullite‐SiF4
Authors: Moyer John R.
Published: April 2005

At 1 atm of SiF4, mullite and SiF4 react below 660° 7°C to form A1F3 and SiO2. From 660° to 1056°± 5°C, the product is fluorotopaz. Mullite is stable in the presence of 1 atm of SiF4 above 1056°C. The transition temperatures at other pressures of SiF4 can be calculated from log p(atm) = 11.587 – 10811/T(K) and log p(atm) = 9.9609 – 13238/T(K). The phase diagram shows only gas–solid equilibria, but there is evidence for a metastable melt from which acicular mullite and fluorotopaz grow.
Partial Conductivities in SrTiO3: Bulk Polarization Experiments, Oxygen Concentration Cell Measurements, and Defect‐Chemical Modeling
Authors: Denk Ingrid , Münch Wolfram , Maier Joachim
Published: April 2005

Knowledge of the exchange kinetics of O2 in SrTiO3 allows us to design appropriate strategies to separate the ionic and the electronic conductivity. In the low‐temperature range, where the overall surface reaction is very slow compared to bulk diffusion and measuring time, electrochemical cells of the type Pt|SrTiO3|Pt are self‐blocking and self‐sealing and a Wagner–Hebb‐type polarization succeeds without the necessity of using selectively blocking electrodes. In the present study the ionic conductivity data obtained for Feand Ni‐doped SrTiO3 in this way are compared to data obtained from the analysis of the oxygen partial pressure dependence of the total conductivity as well as to defect chemical calculations. In complete contrast to the low temperature situation, at high temperatures, where the surface reaction is fast, the emf technique is conveniently applicable. Results are presented for Pt, O2|SrTiO3|O2, Pt cells. The conductivity behavior of SrTi(Fe)O3 as a function of temperature (20°–1000°C) is complex, due to partially frozen‐in equilibria, but even details can be quantitatively understood in terms of a simple defect chemistry. The turnover of the diffusion‐controlled regime to the surface reaction‐controlled regime can be shifted to significantly lower temperatures by using YBa2Cu3O7–8 electrodes.
Influence of Substrate Temperature on Physical Structure of AlN Thin Films Prepared on Polycrystalline MoSi2 by rf Magnetron Sputtering
Authors: Akiyama Morito , Kokabi Hamid Reza , Nonaka Kazuhiro , Shobu Kazuhisa , Watanabe Tadahiko
Published: April 2005

c‐axis‐oriented aluminum nitride thin films were prepared on polycrystalline molybdenum disilicide substrates by rf magnetron sputtering at substrate temperatures of 50°–500°C. The films with the best orientation and crystallinity were prepared at 300°C. The dependence of film microstructure on substrate temperature was investigated by atomic force microscopy (AFM). Consequently, the microstructure changed in accordance with the model proposed by Thornton. It was found that the orientation and crystallinity of the films were optimal when the films consisted of dense fibrous grains. Further, it was confirmed that piezoelectric measurements could be made from the films during mechanical impacts.
Thermodynamics of the Zr‐H System
Authors: Wang Wei‐E , Olander Donald R.
Published: April 2005

The consistencies among the reported univariant hydrogen pressures in the three two‐phase regions of the Zr‐H system, aZr/δZrH2‐xαZr/βZr, and βRZr/δZrH2–x, are evaluated with the thermodynamic constraint derived by Speiser.16 Hydrogen dissolution in αZr is evaluated by checking the consistencies among the Sieverts’law constant, the terminal solubility, and the corresponding two‐phase univariant pressures involving this phase. A modified Sieverts’law is proposed for the complicated behavior of hydrogen dissolution in βZr. An analytical compositiontemperature‐pressure relationship for δZrH2–x is established by using the quasi‐chemical model derived by Arita et al. The thermodynamic constraint of the free energy of formation of ZrH2 shows that the value measured by Fredricken et al. is the most reliable. In addition, a more accurate free energy of formation of zirconium hydride at the upper phase boundary of αZr/δZrH2–x two‐phase region is suggested.
Phase Stability Study on the Remelting Reaction in Ca2SiO4 Solid Solutions
Authors: Fukuda Koichiro , Maki Iwao , Ito Suketoshi , Yoshida Hideto
Published: April 2005

A pseudobinary phase equilibrium diagram has been established for the P2O5‐bearing Ca2SiO4‐CaFe4O7 system to confirm the occurrence of remelting reaction in α‐Ca2SiO4 solid solutions (C2S(ss)). The reaction started at 1290°C immediately after the α‐to‐α′H transition and finished at 1145°C. The reaction products were made up of about 1 wt% of liquid and 99 wt% of solid α′H‐C2S(ss). The liquid exsolved at 1290°C was rich in Fe2O3, consisting of about 30 wt% of Ca2SiO4 and 70 wt% of CaFe4O7. The liquid coexisting with α‐C2S(ss) precipitated new α′‐phase crystals in association with the remelting reaction.
Synthesis of AI2O3‐AI Composites by Reactive Metal Penetration
Authors: Loehman Ronald E. , Ewsuk Kevin , Tomsia Antoni P.
Published: April 2005

Ceramic‐metal composites have been made to near net‐shape by reactive penetration of dense ceramic preforms by molten Al. In contrast to processes involving physical infiltration of a porous medium, this process works with dense ceramic preforms. Ceramic‐metal composite formation by reactive metal penetration is driven by a strongly negative Gibbs energy for reaction. For Al, the general form of the reaction is (x + 2)Al + (3/y)MOy, → Al2O3+ M3Alx, where MOy, is an oxide that is wet by molten Al. In low Po2 atmospheres and at temperatures above about 900°C, molten Al reduces mullite to produce Al2O3 and silicon. The Al/mullite reaction has a ΔGr°(1200 K) of −1014 kJ/mol and, if the mullite is fully dense, the theoretical volume change on reaction is less than 1%. Experiments with commercial mullite containing a silicate grain boundary phase average less than 2% volume change on reaction. In the Al/mullite system, reactive metal penetration produces a fine‐grained alumina skeleton with an interspersed metal phase. With enough excess aluminum, mutually interpenetrating ceramic‐metal composites are produced. Properties measurements show that ceramic‐metal composites produced by reactive metal penetration of mullite by Al have a Young's modulus and hardness similar to that of Al2O3, with improved fracture toughness ranging from 5 to 9 Mpa·m1/2. For penetration times less than 1 h, reaction layer thickness varies as the square root of time, which allows ceramic‐metal composite coatings to be fabricated by controlling the penetration time. Thermodynamic calculations indicate that other compositions also are candidates for in situ reaction synthesis, which suggests that reactive metal penetration may be a general route to composite synthesis with the prospect for near net‐shape processing.
Particle/Matrix Interface and Its Role in Creep Inhibition in Alumina/Silicon Carbide Nanocomposites
Authors: Ohji Tatsuki , Hirano Takeshi , Nakahira Atsushi , Niihara Koichi
Published: April 2005

This study focuses on interfacial bonding between intergranular silicon carbide particles and an alumina matrix, to determine the creep inhibition mechanism of alumina/ silicon carbide nanocomposites. It is revealed that the silicon carbide/alumina interface possesses much stronger bonding than the alumina/alumina interface through three approaches: investigation of fracture toughness and fracture mode and consideration of internal thermal stresses acting at grain boundaries, estimation of equilibrium thickness of intergranular glassy films by force balance, and direct observation of grain boundaries by TEM. The rigid bonding of alumina/silicon carbide interfaces causes inhibition of vacancy nucleation and annihilation at the interfaces, causing remarkably improved creep resistance of the nanocomposite.
Subcritical Crack Growth in Silica Optical Fibers in Wide Range of Crack Velocities
Authors: Muraoka Mikio , Abé Hiroyuki
Published: April 2005

Crack growth in silica optical fibers was measured directly in a wide range of crack velocities da/dt (10−13 < da/dt < 10−5 m/s) by improving our previous method. The slope in log‐log plots of the crack velocity versus the stress intensity factor data was revealed to increase with the crack velocity, e.g., slope, 23.3 for da/dt < 10−10 m/s, and 39.7 for da/dt > 1(10−8 m/s. The data were also found to be fitted well by the exponential law in the whole range of da/dt, rather than the power law. Additionally, the fiber data were shown to be close to those reported for bulk silica specimens having large cracks for high crack velocities where the bulk specimens were tested.
Tensile Behavior of Cement‐Based Composites with Random Discontinuous Steel Fibers
Authors: Li Victor C. , Wu Hwai‐Chung , Maalej Mohamed , Mishra Dhanada K. , Hashida Toshiyuki
Published: April 2005

In this paper, the tensile properties of cement‐based composites containing random discontinuous steel fibers are reported. Direct tensile tests were performed to study the effects of fiber length (hence fiber aspect ratio), interfacial bonding, and processing conditions on composite properties. Composite tensile strength and ductility are highlighted and discussed.
Hysteresis Loops and the Inelastic Deformation of 0/90 Ceramic Matrix Composites
Authors: Domergue Jean‐Marc , Heredia Fernando E. , Evans Anthony G.
Published: April 2005

Hysteresis measurements obtained on 0/90 SiC/CAS and SiC/SiC have been used to analyze the interface responses. Four parameters have been derived from these measurements. These relate to the compliance change caused by matrix cracking, the frictional resistance of the interface, the interface debond resistance, and the residual stress. These parameters have been used to predict the stress/ strain curves. Preliminary estimates of stress partitioning between the plies have been used to estimate constituent properties, such as the friction stress.
Combustion Synthesis/Dynamic Densification of a TiB2‐SiC Composite
Authors: Hoke Darren A. , Kim Do Kyung , LaSalvia Jerry C. , Meyers Marc A.
Published: April 2005

The Ti + 2B exothermic chemical reaction was used in combination with a high‐velocity forging step to produce dense TiB2‐(20 vol%)SiC composites. Densities in excess of 96 % of the theoretical were achieved for both SiC particulate and fiber additions. X‐ray diffractometry revealed the products of the reaction to be TiB2 and SiC. The microstructures are composed of spheroidal TiB2 phase, a highly contiguous SiC binder phase, and an apparent eutectic between TiB2 and SiC located at regions of preexisting SiC additions. These microstructural features suggest that SiC underwent a peritectic phase transformation. Thermodynamic analysis predicts that at least 41 vol% SiC addition is needed to prevent the loss of the starting morphologies by the peritectic reaction.
Superplastic Alumina at Temperatures below 1300°C Using Charge‐Compensating Dopants
Authors: Xue Liang A. , Chen I‐Wei
Published: April 2005

To achieve low‐temperature superplasticity in alumina, we have introduced charge‐compensating dopants, Ti4+ and Mn2+, which jointly have a high solubility and significantly enhance the diffusion and deformation processes during sintering and forming. Zirconia as a second‐phase pinning agent has also been incorporated to impart microstructural stability against static and dynamic grain growth. The superplastic alumina obtained can be shape‐formed under biaxial tension to 100% engineering strain at temperatures below 1300°C. Deformation characteristics of this alumina at temperatures from 1200° to 1400°C and at strain rates from 4 × 10‐6 to 3 × 10‐3/s are described. The origin of enhanced kinetics is attributed to the formation and dissociation of dopant‐defect complexes.
Structure Evolution in Hydrothermally Processed (<100°C) BaTiO3 Films
Authors: Slamovich Elliott B. , Aksay Ilhan A.
Published: April 2005

Thin films of cubic BaTiO3 were processed hydrothermally at 40°–80°C by reacting thin layers of titanium organo metallic liquid precursors in aqueous solutions of either Ba(OH)2 or a mixture of NaOH and BaCl2. All films (thickness ∼1 μm) were polycrystalline with grain sizes ranging from nano‐ to micrometer dimensions. BaTiO3 formation was facilitated by increasing [OH‐], [Ba2+], and the temperature. The film structure was related to the nucleation and growth behavior of the BaTiO3 particles. Films processed at relatively low [OH‐], [Ba2+], and temperatures were coarse grain and opaque, but increasing [OH‐], [Ba2+], and temperature caused the grain size to decrease, resulting in transparent films.
Interannual variation in Neocalanus biomass in the Oyashio waters of the western North Pacific
Authors: TADOKORO KAZUAKI , CHIBA SANAE , ONO TSUNEO , MIDORIKAWA TAKASHI , SAINO TOSHIRO
Published: April 2005

We examined the interannual variation in Neocalanus copepod biomass in the Oyashio waters in spring and summer from 1972 to 1999. In the mid‐1970s, mesozooplankton biomass in spring was high; however, it decreased significantly in the late 1970s. The timing of the decrease in mesozooplankton biomass corresponded to the 1976/77 climatic regime shift. The biomass of N. flemingeri, which dominated the Neocalanus community, was roughly constant from 1980 to 1999. Although species‐level estimates of Neocalanus biomass were not available for the 1970s, a previous study reported that Neocalanus copepods were the predominant mesozooplankton in the Oyashio waters in spring during the 1970s. Neocalanus copepods dominated the mesozooplankton community throughout the 1970s, and their biomass decreased in the late 1970s. Springtime net community production, an index of new production, also decreased in the late 1970s. We suggest that the reduction in new production negatively affected Neocalanus food availability, resulting decreased copepod biomass. New production may have been limited by a combination of subsurface iron supplies, increased vertical density gradient, and reduced vertical water mixing in winter, which resulted in diminished iron entrainment in winter. In summer, mesozooplankton biomass significantly decreased and increased synchronously with the 1976/77 and 1988/89 climatic regime shifts. The biomass of N. plumchrus, which dominated the Neocalanus community, was low in the 1980s and increased in the early 1990s. The biomass of the second‐most dominant copepod, N. cristatus, also increased in the early 1990s. Neocalanus copepods were reported to be a dominant component of the mesozooplankton community in the 1970s; Neocalanus biomass was high in the mid‐1970s and decreased in the late 1970s. Japanese sardine (Sardinops melanostictus), an important predator of Neocalanus copepods, exhibited interannual variation in standing stock that was inversely related to mesozooplankton biomass. At their peak in 1984, sardines consumed 32–138% of the daily Neocalanus production during summer. Therefore, predation pressure on Neocalanus by Japanese sardine is likely to affect interannual variation in mesozooplankton biomass during the summer.
Standards for ecologically successful river restoration
Authors: PALMER M.A. , BERNHARDT E.S. , ALLAN J. D. , LAKE P.S. , ALEXANDER G. , BROOKS S. , CARR J. , CLAYTON S. , DAHM C. N. , FOLLSTAD SHAH J. , GALAT D. L. , LOSS S. G. , GOODWIN P. , HART D.D. , HASSETT B. , JENKINSON R. , KONDOLF G.M. , LAVE R. , MEYER J.L. , O'DONNELL T.K. , PAGANO L. , SUDDUTH E.
Published: April 2005

Increasingly, river managers are turning from hard engineering solutions to ecologically based restoration activities in order to improve degraded waterways. River restoration projects aim to maintain or increase ecosystem goods and services while protecting downstream and coastal ecosystems. There is growing interest in applying river restoration techniques to solve environmental problems, yet little agreement exists on what constitutes a successful river restoration effort.

We propose five criteria for measuring success, with emphasis on an ecological perspective. First, the design of an ecological river restoration project should be based on a specified guiding image of a more dynamic, healthy river that could exist at the site. Secondly, the river's ecological condition must be measurably improved. Thirdly, the river system must be more self‐sustaining and resilient to external perturbations so that only minimal follow‐up maintenance is needed. Fourthly, during the construction phase, no lasting harm should be inflicted on the ecosystem. Fifthly, both pre‐ and post‐assessment must be completed and data made publicly available.

Determining if these five criteria have been met for a particular project requires development of an assessment protocol. We suggest standards of evaluation for each of the five criteria and provide examples of suitable indicators.

Synthesis and applications. Billions of dollars are currently spent restoring streams and rivers, yet to date there are no agreed upon standards for what constitutes ecologically beneficial stream and river restoration. We propose five criteria that must be met for a river restoration project to be considered ecologically successful. It is critical that the broad restoration community, including funding agencies, practitioners and citizen restoration groups, adopt criteria for defining and assessing ecological success in restoration. Standards are needed because progress in the science and practice of river restoration has been hampered by the lack of agreed upon criteria for judging ecological success. Without well‐accepted criteria that are ultimately supported by funding and implementing agencies, there is little incentive for practitioners to assess and report restoration outcomes. Improving methods and weighing the ecological benefits of various restoration approaches require organized national‐level reporting systems.
The effects of organic agriculture on biodiversity and abundance: a meta‐analysis
Authors: BENGTSSON JANNE , AHNSTRÖM JOHAN , WEIBULL ANN‐CHRISTIN
Published: April 2005

The efficiency of agricultural subsidy programmes for preserving biodiversity and improving the environment has been questioned in recent years. Organic farming operates without pesticides, herbicides and inorganic fertilizers, and usually with a more diverse crop rotation. It has been suggested that this system enhances biodiversity in agricultural landscapes. We analysed the effects of organic farming on species richness and abundance using meta‐analysis of literature published before December 2002.

Organic farming usually increases species richness, having on average 30% higher species richness than conventional farming systems. However, the results were variable among studies, and 16% of them actually showed a negative effect of organic farming on species richness. We therefore divided the data into different organism groups and according to the spatial scale of the study.

Birds, insects and plants usually showed an increased species richness in organic farming systems. However, the number of studies was low in most organism groups (range 2–19) and there was significant heterogeneity between studies. The effect of organic farming was largest in studies performed at the plot scale. In studies at the farm scale, when organic and conventional farms were matched according to landscape structure, the effect was significant but highly heterogeneous.

On average, organisms were 50% more abundant in organic farming systems, but the results were highly variable between studies and organism groups. Birds, predatory insects, soil organisms and plants responded positively to organic farming, while non‐predatory insects and pests did not. The positive effects of organic farming on abundance were prominent at the plot and field scales, but not for farms in matched landscapes.

Synthesis and applications.Our results show that organic farming often has positive effects on species richness and abundance, but that its effects are likely to differ between organism groups and landscapes. We suggest that positive effects of organic farming on species richness can be expected in intensively managed agricultural landscapes, but not in small‐scale landscapes comprising many other biotopes as well as agricultural fields. Measures to preserve and enhance biodiversity should be more landscape‐ and farm‐specific than is presently the case.
Effects of radio‐collar position and orientation on GPS radio‐collar performance, and the implications of PDOP in data screening
Authors: D'EON ROBERT G. , DELPARTE DONNA
Published: April 2005

Global positioning system (GPS) radio‐telemetry has become an important wildlife research technique worldwide. However, understanding, quantifying and managing error and bias in raw GPS radio‐telemetry data sets requires much more work. In particular, error and bias resulting from position (angle away from vertical) and orientation (compass direction) of GPS radio‐collars on free‐ranging animals is currently unknown.

We tested the effects of collar position and orientation on GPS radio‐collar performance using five stationary GPS radio‐collars. We also investigated the use of positional dilution of precision (PDOP) as a method for screening data with high location errors.

Orientation had no statistical effect on fix rates or location errors. The biggest source of variation was attributed to collar position, which resulted in significantly lower performance at angles below 90° from vertical.

PDOP‐based screening was effective and can be used to lower location error, but the trade‐off between higher location accuracy and data loss (potentially leading to new bias) must be assessed.

Synthesis and applications. The results of this study refine our understanding of error and bias in GPS radio‐telemetry data. We suggest that collar orientation can safely be disregarded, whereas radio‐collar position remains a large potential source of error and bias. This finding has major implications regarding animal activity and GPS radio‐telemetry research. Researchers need to quantify and account for biases resulting from animals moving through heterogeneous terrain and habitats.
Effects of ski piste preparation on alpine vegetation
Authors: WIPF SONJA , RIXEN CHRISTIAN , FISCHER MARKUS , SCHMID BERNHARD , STOECKLI VERONIKA
Published: April 2005

Ski resorts increasingly affect alpine ecosystems through enlargement of ski pistes, machine‐grading of ski piste areas and increasing use of artificial snow.

In 12 Swiss alpine ski resorts, we investigated the effects of ski piste management on vegetation structure and composition using a pairwise design of 38 plots on ski pistes and 38 adjacent plots off‐piste.

Plots on ski pistes had lower species richness and productivity, and lower abundance and cover of woody plants and early flowering species, than reference plots. Plots on machine‐graded pistes had higher indicator values for nutrients and light, and lower vegetation cover, productivity, species diversity and abundance of early flowering and woody plants. Time since machine‐grading did not mitigate the impacts of machine‐grading, even for those plots where revegetation had been attempted by sowing.

The longer artificial snow had been used on ski pistes (2–15 years), the higher the moisture and nutrient indicator values. Longer use also affected species composition by increasing the abundance of woody plants, snowbed species and late‐flowering species, and decreasing wind‐edge species.

Synthesis and applications. All types of ski piste management cause deviations from the natural structure and composition of alpine vegetation, and lead to lower plant species diversity. Machine‐grading causes particularly severe and lasting impacts on alpine vegetation, which are mitigated neither by time nor by revegetation measures. The impacts of artificial snow increase with the period of time since it was first applied to ski piste vegetation. Extensive machine‐grading and snow production should be avoided, especially in areas where nutrient and water input are a concern. Ski pistes should not be established in areas where the alpine vegetation has a high conservation value.