bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Transmission Line Failures on the Cost/Risk-Based Spinning Reserve Allocation
Authors: Goel Lalit , Song Z , Wang P
Published: December 2005

In deregulated power systems spinning reserve (SR) can be allocated to different ancillary service providers at different locations based on supplier bids and customer choices on reliability. This paper investigates the impact of transmission line failures using a cost/risk-based spinning reserve allocation method (CRSRAM). The proposed method provides minimum spinning reserve cost, while securing the reliability risk at a minimum in the presence of not only generating unit outages but also transmission line failures. The implementation of this technique in a SR market to determine the SR schedules is presented in the paper. The IEEE Reliability Test System (RTS) has been used to illustrate the applications of the proposed method.
Optimization Methods for Electric Power Systems: An Overview
Authors: Bansal R. C.
Published: December 2005

Power systems optimization problems are very difficult to solve because power systems are very large, complex, geographically widely distributed and are influenced by many unexpected events. It is therefore necessary to employ most efficient optimization methods to take full advantages in simplifying the formulation and implementation of the problem. This article presents an overview of important mathematical optimization and artificial intelligence (AI) techniques used in power optimization problems. Applications of hybrid AI techniques have also been discussed in this article.
Robust Frequency Stabilisation By Coordinated Superconducting Magnetic Energy Storage With Static Synchronous Series Compensator
Authors: Ngamroo Issarachai
Published: December 2005

As large load disturbances with changing frequency in the vicinity of the inter-area oscillations mode occur in an interconnected power system, a system frequency may be heavily perturbed and oscillatory. To stabilise frequency oscillations, the active power controlled by a superconducting magnetic energy storage (SMES) unit placed in a power system, can be utilised. However, it may not be feasible to locate a SMES unit in every area of a multi-area interconnected power system due to the economic reason. Therefore, it should be advantageous if a SMES unit located in an area is available for frequency stabilisation of other interconnected areas. To implement this concept, a static synchronous series compensator (SSSC), can be applied to coordinate with a SMES unit to stabilise frequency oscillations. On the other hand, variations of system parameters, several load changes etc., cause system uncertainties. To enhance the robustness of frequency stabilisers against uncertainties, this paper focuses on a robust frequency stabilisation by SMES in co-ordination with SSSC. To take system uncertainties into account, the multiplicative uncertainty is included in system modeling. As a result, the system robust stability can be easily guaranteed in terms of the multiplicative stability margin (MSM). The structure of frequency stabiliser equipped with SMES and SSSC is a second-order lead/lag compensator. Based on the proposed optimisation technique, control parameters of frequency stabilisers can be automatically tuned by a tabu search. Consequently, the desired damping ratio of the target inter-area mode and the best MSM are achieved. Simulation studies in a two-area interconnected power system confirm the high robustness of the coordinated SMES with SSSC against several uncertainties.
Travelling Wave-Based Fault Location Scheme for Aged Underground Cable Combined with Overhead Line
Authors: Gilany Mahmoud I. , Tag Eldin El Sayed M. , Abdel Aziz Mohamed Mamdouh , Ibrahim Doaa K.
Published: December 2005

This paper presents a novel wavelet-based travelling wave fault location algorithm for aged underground cables in transmission systems. Such transmission systems consist of overhead lines combined with underground power cables. Applying the singularity detection feature of wavelets as a powerful signal processing tool, the first and second initial arrival of the voltage travelling waves at the first end of the overhead as well as at the terminal end of the aged cable line can be identified reliably without the need for detection the sign of these waves. In this paper modal signals, rather than the phase signals, are the inputs to the relay.The proposed algorithm is capable of eliminating the effect of the change in the propagation velocity of the travelling waves over the age of the cable. It can be used on-line following the operation of digital relays or off-line using the data stored in the digital transient recording apparatus. Extensive simulation studies carried out using ATP/EMTP show that the proposed algorithm provides an accepted degree of accuracy in fault location under different fault conditions.
Distributed Generation Opportunity under Availability Based Tariff and Reliability Considerations
Authors: Agalgaonkar A. P. , Kulkarni S. V. , Khaparde S. A. , Soman S. A.
Published: December 2005

Availability Based Tariff (ABT) has been implemented in all the regional grids of India for improving grid discipline by frequency dependent pricing. Currently it is limited to short-term energy transactions between the beneficiary States and Central generating stations without the need for negotiations on price or quantum in real time. In the present scenario, Independent Power Producers (IPP), Captive Power Plants (CPP), small Distributed Generation (DG) like mini-turbine, fuel cell, etc., are not considered under ABT. DG units are normally modular in size and they can be placed close to consumers so as to reduce the T&D costs and losses. Hence, they need to be encouraged so as to meet the ever-increasing electricity demands of Indian power sector within the financial constraints. In this paper, impact of IPPs, CPPs and DGs on intra-State ABT is studied. This paper also proposes to study the impact of grid connected DG on network availability and reliability. The improvement in system reliability is studied after evaluating reliability indices like SAIFI, SAIDI, etc., with the inclusion of DG.
Detecting High Impedance Faults Utilizing Combined Phase Voltages with Neutral Line Current
Authors: Yang Ming-Ta , Gu Jhy-Cherng
Published: December 2005

This study aims to present a new approach to detecting high impedance faults (HIFs) in the distribution feeder. Discrete wavelet transformations (DWT) and neural networks (NN) have been widely applied in power system research. Consequently, this study developed a novel technique to discriminate effectively between the HIFs and the switch operations by combining DWT with NN. The proposed approach has three distinct features. First, the input signal of this algorithm is neutral line current, rather than the conventional currents based on three individual phases. Second, HIFs identification uses the details at levels 3, 4 and 5 and the approximations at level 5 of the neutral line current are utilized for. Third, the input signals of the three-phase voltages classify the faulty and healthy phases. The results of simulation and field staged fault clearly show that the proposed technique can accurately identify the HIFs in the distribution feeder.
A LQG Based Load Frequency Controller in a Competitive Electricity Environment
Authors: Tyagi Barjeev , Srivastava S.C.
Published: December 2005

This paper presents the design of a Linear Quadratic Gaussian (LQG) regulator for the frequency control of a multi-area power system in a restructured competitive electricity market environment. A general model of the LQG regulator has been developed for multi-area system (with hydro and thermal generators) having Poolco and bilateral transactions. To account for the modeling uncertainties and non-measurable states, a Kalman filter has been designed to estimate the state variables. The controller uses these estimates, optimizes a given performance index, and reschedules the generators outputs according to their bids for the frequency regulation. The functioning of the proposed LQG regulator has been demonstrated on a four area test system and the results have been compared with those obtained by using an optimal PID controller.
New Criteria for Estimating Voltage Unbalance Due to Special Connected Transformers in High Speed Railway Systems
Authors: Chu Wen-Shyan , Gu Jyh-Cherng , Chen Bin-Kwie , Lee San-Yi
Published: December 2005

Specially connected transformers can reduce the voltage unbalance in a High Speed Railway (HSR) power supply system. Differently connected transformers reduce unbalance differently. Traditionally, a two-dimensional figure is used to represent the degree of unbalance associated with specially connected transformers. However, such a figure cannot completely express the conditions under which the voltage unbalance factor (VUF) is maximized. This work proposes a new approach to creating figures that represent the VUF of specially connected transformers under different dispatch schedules. Besides helping engineers to estimate voltage unbalance associated with various connected transformers, the analytical results can also provide a valuable reference for train dispatchers of HSR to plan dispatching.
Approximate Value Iteration in the Reinforcement Learning Context. Application to Electrical Power System Control.
Authors: Ernst Damien , Glavic Mevludin , Geurts Pierre , Wehenkel Louis
Published: December 2005

In this paper we explain how to design intelligent agents able to process the information acquired from interaction with a system to learn a good control policy and show how the methodology can be applied to control some devices aimed to damp electrical power oscillations. The control problem is formalized as a discrete-time optimal control problem and the information acquired from interaction with the system is a set of samples, where each sample is composed of four elements: a state, the action taken while being in this state, the instantaneous reward observed and the successor state of the system. To process this information we consider reinforcement learning algorithms that determine an approximation of the so-called Q-function by mimicking the behavior of the value iteration algorithm. Simulations are first carried on a benchmark power system modeled with two state variables. Then we present a more complex case study on a four-machine power system where the reinforcement learning algorithm controls a Thyristor Controlled Series Capacitor (TCSC) aimed to damp power system oscillations.
Generalized Steady State Modeling and Analysis of Three Phase Self Excited Induction Generators
Authors: Singaravelu S , Velusami Dr. S
Published: December 2005

This paper presents two mathematical models based on graph theory, and a fuzzy logic approach for the steady state analysis of three phase self excited induction generator with and without series compensation. The first model is developed using nodal admittance method and the second model is developed using loop impedance method. Both models results in simple matrix form which are convenient for computer solutions. Since these models are more generalized the steady state performance of the three phase self excited induction generator can be easily obtained with and without series compensation along with fuzzy logic algorithm. These models are so flexible, wherein an element like core loss component can be included or eliminated if required and also the leakage reactance of the stator (Xls) and rotor (Xlr) can be handled separately, by avoiding the assumptions Xls=Xlr without any modifications in the models. Next to carry out the steady state analysis, a fuzzy logic approach is used first time to find any combinations of unknown variables using above models. The analysis presented is validated by experimental results.
Sizing of an Innovative and Improved Meat Smoking System
Authors: Bruneau Denis M , Sebastian Patrick , Lecompte Jean-Yves , Collignan Antoine , Rochery Vincent
Published: December 2005

There has been recent interest in developing small-scale smoking technologies that respect French sanitary recommendations concerning benzo(a)pyrene deposition on food. The conceptual and embodiment phases of design, and the sizing of a smoker in which this deposition phenomenon is limited are reviewed in this paper. The conceptual phase of design has lead to a process based on the operations of smoking, heating and drying units, using cooled smoke, radiant plates and supplying flows of this cooled smoke directly to the product. For marketing reasons, the power supply is exclusively derived from the combustion of small logs and the smoke comes from sawdust pyrolysis, this smoke being cooled by flowing through a heat exchanger using ice as a cold source. The embodiment phase of design has lead to a versatile system in terms of smoking, heating and drying functionalities. The sizing of this system is based on knowing the drying kinetic of the product in a traditional smoke house (boucan); it was performed by estimating heat and mass transfer phenomena occurring between the product and its surroundings. It leads to a kiln having a thermodynamic efficiency close to 13%.
Foreign Body Contamination of Food - Scanning Electron Microscopy and Energy Dispersive Spectroscopy as Tools for Identification
Authors: James Bryony
Published: December 2005

Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are powerful tools for the characterisation of foreign body (FB) or particulate contamination of food products. Whether the result of processing, packaging or interaction with consumers, once identified foreign body contamination needs to be characterised as rapidly and efficiently as possible in order to trace its source. An outline of the operation and capabilities of SEM/EDS is presented in order to highlight its application to FB identification. Three case studies are presented, one of FB contamination that was caused by agglomerated flour particles, one of a glass fragment reported by a consumer in a jar of baby food and one of a suspected dental implant in a food product.
A Methodology for the Evaluation of Mechanical Properties of Sausage Based on Tensile and Compression Tests
Authors: Daros Fabiane Guerra , Amico Sandro Campos , Masson Maria Lucia
Published: December 2005

The food product called sausage is a meat emulsion in which the fat drops are dispersed in an aqueous matrix containing soluble proteins, other muscle components and conjunctive tissue. The rheological behavior of sausage needs to be known in order to monitor the quality and acceptance of this product and the evaluation of its response, for instance, to different packaging situations, which is a result of their stress-strain behavior when subjected to a particular static or dynamic stress. A methodology for the assessment of mechanical properties of sausage has been developed. A universal testing machine was used and tests were carried out in sausage available in the market to validate the methodology. Tensile and compression tests were carried out and test conditions were varied, including strain rate and specimen shape and temperature. The influence of the skin on the determinations was also assessed. The need to control cross-section shape was identified, and a dumb-bell and a cylinder specimen shape were proposed for tensile and compression tests, respectively. Temperature is critical and higher temperatures decrease tensile and compressive strengths. Sausage resistance is also sensitive to the strain rate, especially at low values. A travel speed of 50 mm/min seems to be appropriate since variations around this value did not affect tensile or compressive strength determinations. The presented methodology was found adequate to the intended objectives, producing reliable and reproductive results.
Effects of Impeller Speed, Atomising Air Flow Rate and Fluidising Temperature in Agitated Fluidised Bed Granulation of Cocoa-Milk Powders
Authors: Anuar Mohd Shamsul , Tasirin Siti Masrinda
Published: December 2005

Mechanically agitated fluid bed granulators with inserted impeller are currently favoured by the industry due to better particle mixing, heat transfer and effective particle growth. However, effects of operational variables such as impeller speed, atomising air flow rate and fluidising temperature on the physical characteristics of the generated granules are still not fully quantified. Scaling-up of industrial fluid bed granulation processes especially in the pharmaceutical industry are done empirically. In this paper, a study is described on the effects of impeller speed, atomising air flow rate and fluidising temperature on the flowability, moisture content, mean particle size and size distribution of the granulated cocoa-milk drink powder in an agitated fluid bed granulation process. Findings showed that when all the values of the three investigated operational parameters were increased, granules with better flowability characteristics, lower moisture content, smaller and more uniformed granules were obtained in the range tested.
Microbial and Physico-Chemical Characteristics of Dried Meat Processed by Different Methods
Authors: Rahman Mohammad Shafiur , Salman Zeinab , Kadim Isam T , Mothershaw Ann , Al-Riziqi Mohd Hamad , Guizani Nejib , Mahgoub Osman , Ali Amanat
Published: December 2005

Thirty longissimus dorsi (LD) muscles from Omani male goats were dried by five methods (sun, air, vacuum, freeze and modified atmosphere drying). Dried strips from the longissimus dorsi samples were evaluated for microbial, chemical and fatty acid composition and physical quality (pH, expressed juice, rehydration ratio, and color L*, a* and b* values). The method of drying had a significant effect on the microbial counts, pH, volume of expressed juice, color, rehydration ratio, and fatty acids content of LD samples. Immediately after drying and 6 weeks of storage, sun dried sample showed significantly higher aerobic plate counts, and levels of Pseudomonas and Staphylococcus compared to other methods of drying. The drying method significantly affected the types of mold growth in the samples.
Effect of Emulsifying Salts on Casein Peptization and Apparent Viscosity of Processed Cheese
Authors: Dimitreli Georgia , Thomareis Apostolos S , Smith Peter G.
Published: December 2005

The influence of five different emulsifying salts on casein peptization (dissociation) and apparent viscosity of processed Gouda cheese was studied. Casein peptization was evaluated as peptization coefficient in the final product, while apparent viscosity was determined as flow behavior and consistency indices in the product during processing before cooling. Increasing moisture content and pH of processed cheese samples generally increases peptization coefficient, however the type of emulsifying salt showed to play an important role also. On the contrary, independently of the type of emulsifying salt, predictive regression models were suggested in order to express flow behavior index and consistency index versus chemical composition and pH. Increasing moisture content or reducing pH increases the flow behavior index. Consistency index, and thus the apparent viscosity, of processed cheese samples was increased when the moisture content was reduced, and when pH and the soluble casein content were increased.
Effect of Process Conditions on Composition and Properties of Pectin and Apparent Viscosity of Sterilized and Concentrated Pulp of Tomatoes
Authors: Masson Maria Lucia , Malvestiti Marta , Haminiuk Mr. Charles Windson Isidoro , Reicher Fany , Anjos Adilson dos , Siqueira Adir Alessio
Published: December 2005

Tomato pulp treated at industrial unit conditions was utilized to determine the physical and chemical changes on pectin substances properties and its correlation to the consistency of tomato pulp, hot break pretreated product, concentrated pulp at 70oC/30 min and sterilized pulp at 102oC/10 min. The assays carried out were: apparent viscosity, serum separation degree, precipitate weight ratio, insoluble solids and pectic substances as uronic acid, fractionated according to their solubility in water, 0.2% ammonium oxalate, 0.05N hydrochloric acid and 0.05N sodium hydroxide solutions. Concentration and sterilization cause reduction in the apparent viscosity, the precipitate weight ratio and increasing of the serum separation degree of the suspension compare to tomato pulp submitted only to pre-treatment and those conditions didnt affect significantly the total uronic acid and insoluble solids in water. However, changes occurred on chemical composition, detected into fractions of pectic substances expressed as uronic acid in all samples; results for pre-treated pulp sample to sterilized pulp samples (final product) show a high water solubilization of the fractions of the pectic substances, around 31%, confirmed by an increment of 24% in the water soluble fraction. A high correlation was established between the concentration of water-insoluble fractions and apparent viscosity, precipitate weight ratio and serum separation degree.
A Nonparametric Dimension Test of the Term Structure
Authors: Gil-Bazo Javier , Rubio Gonzalo
Published: December 2005

In an economy with multiple sources of risk, the short-term interest rate does not capture all the information that determines the conditional distribution of bond yields. This is also true for path-dependent term structure models. In either case, the current short rate level is not a sufficient statistic for the conditional density of future short rates. This paper studies the empirical relevance of both issues from a time-series nonparametric perspective. The analysis is formulated as a test for the dependence of the short rate drift and diffusion on variables other than the short rate, and exploits Ait-Sahalia, Bickel, and Stocker (2001) dimension reduction method. The paper explores the finite sample performance of the method and applies the test to US interest rate data. Results reject a single-factor Markovian model, although conclusions are sensitive to the choice of additional conditioning variables.
The Long Memory of the Efficient Market
Authors: Lillo Fabrizio , Farmer J. Doyne
Published: December 2005

For the London Stock Exchange we demonstrate that the signs of orders obey a long-memory process. The autocorrelation function decays roughly as a power law with an exponent of 0.6, corresponding to a Hurst exponent H = 0.7. This implies that the signs of future orders are quite predictable from the signs of past orders; all else being equal, this would suggest a very strong market inefficiency. We demonstrate, however, that fluctuations in order signs are compensated for by anti-correlated fluctuations in transaction size and liquidity, which are also long-memory processes that act to make the returns whiter. We show that some institutions display long-range memory and others don’t.
Neural Tests for Conditional Heteroskedasticity in ARCH-M Models
Authors: de Peretti Christian , Siani Carole
Published: December 2005

This paper deals with tests for detecting conditional heteroskedasticity in ARCH-M models using three kinds of methods: neural networks techniques, bootstrap methods and both combined.As regards the ARCH models, Péguin-Feissolle (2000) developed tests based on the modelling techniques with neural network. However, as regards the ARCH-M models, a nuisance parameter is not identified and the tests are not applicable. To solve this problem, we propose to adapt these neural tests to Davies procedure (1987) leading to new tests. The performance of these latter tests are compared with those of Bera and Ra test (1995).However, Bera and Ra test has not really satisfactory performance and suffer from serious size distortion. Our neural test will have the same problem. To solve this second problem, without loss of power, we apply parametric and nonparametric bootstrap methods on the underlying test statistics.Lastly, to examine the size and the power properties of the tests in small samples, Monte Carlo simulations are carried out with various standard and non-standard models for conditional heteroskedasticity as to illustrate a variety of situations. In addition, the graphical presentation of Davidson and MacKinnon (1998a) is used to show the "true" power of the tests and not only the (nominal) power, as it is often the case, that can be meaningless.
Pleasure, Learning, Video Games, and Life: The Projective Stance
Authors: Gee James Paul
Published: December 2005

This article addresses three questions. First, what is the deep pleasure that humans take from video games? Second, what is the relationship between video games and real life? Third, what do the answers to these questions have to do with learning? Good commercial video games are deep technologies for recruiting learning as a form of profound pleasure, and have much to tell us about what learning could look like in the future should we relinquish the old grammars of traditional schooling. They are extensions of life insofar as they recruit and externalize some fundamental features of how humans orientate themselves in and to the real world when operating at their best. Video games create a projective stance in the sense of a stance toward the world in which we see the world simultaneously as a project imposed on us and as a site onto which we can actively project our desires, values and goals. A special category of games allows players to enact the projective stance of an ‘authentic professional’, thereby experiencing deep expertise of the kind that so widely eludes learners in school.
Computer-Mediated Communication and Culture: A Comparison of ‘Confucian-Heritage’ and ‘Western’ Learner Attitudes to Asynchronous E-Discussions Undertaken in an Australian Higher Educational Setting
Authors: Ramsay Guy
Published: December 2005

While the internationalisation of higher education has made learner diversity a key consideration in tertiary pedagogical practice, research into the application of computer-mediated technologies in this domain has rarely taken into account culture. This article responds to this gap in the research by comparing ‘Confucian-heritage’ and ‘Western’ learners' experience of computer-mediated discussions undertaken as part of an Australian university curriculum. Likert and open-ended question formats reveal that cultural learning styles and behaviours are salient to the computer-mediated learning experience and can inform how learners view its pedagogical applications. While appreciation of the utilitarian benefits is common to both cultural cohorts, Confucian-heritage learners place greater emphasis on the interpersonal benefits. By placing distinctions in learner cultural background at the centre of the study, a more nuanced understanding of computer-mediated communication and its attendant pedagogical applications in higher education emerges.
Pinnacles and Pitfalls: Researcher Experiences from a Web-Based Survey of Secondary Teachers
Authors: Watson Julie , Anderson Neil
Published: December 2005

This article examines the experience of conducting a web-based survey with secondary teachers in Queensland schools. The survey was designed to collect data concerning teachers' attitudes and understanding about students with learning difficulties in their classes. Rather than discuss survey findings, however, the present article focuses on sponsors as a vehicle for online survey promotion, as well as on aspects of survey coverage, rates of response and teacher motivations to participate. Gatekeeping and technical issues emerged as significant issues affecting teacher response. Two hundred and eighty teachers employed in state and non-government schools completed surveys for this exploratory research and constituted a convenience sample for the study.
Education for Sustainable Development: Configuration and Meaning
Authors: González-Gaudiano Edgar
Published: December 2005

The inception of the United Nations Decade of Education for Sustainable Development (2005–14) has excited controversy over the validity of the concept of education for sustainable development (ESD), as well as reactivating a critical review of the environmental education field as a whole. This article analyzes the peculiarities of ESD, the conditions that gave rise to it, the characteristics of its proposed configuration and the implications for environmental education.
Sustainable Development in a Globalizing World: A Few Cautions
Authors: Jickling Bob
Published: December 2005

This article takes the view that in a globalizing context the concept of ‘sustainable development’ should not be assumed uncritically. Further, tensions arise when education is constructed as an instrument for the implementation of this concept, as manifest in the term ‘education for sustainable development’. With critical concern about sustainable development and the tensions arising out of an agenda of educational determinism, this article presents a series of cautions about education for sustainable development. While much good work is being done by educators who work under the label ‘sustainable development’, I argue in the end that education should provide the capacity to transcend this particular conception – to reach outside and beyond sustainable development.
Stultifera Navis: Institutional Tensions, Conceptual Chaos, and Professional Uncertainty at the Beginning of the Decade of Education for Sustainable Development
Authors: Pérez José Gutiérrez , Llorente Mª Teresa Pozo
Published: December 2005

The main idea this article develops is the conceptual chaos, methodological tensions and epistemological conflicts that are being experienced in the field of environmental education as a result of the uncertainty generated by some institutions and international organisms. The authors’ perspective starts from the idea that too many expectations have been invested in the celebration of the Decade of Education for Sustainable Development. The celebration will contribute to making the tensions and fractures grow between the different collectives and professional cultures that inhabit this educational field. While some will find their channels of expression waning and their work models delegitimated, others will increase their popularity and extend their hegemonic power over the dominant models of intervention and the securing of financial resources through the programs and grant competitions they enter. The reason for these tensions lies in the underlying focus promoted by the model of celebration that has been advocated by the institutions leading the process.
Evaluation of ligament fibroblast viability in ruptured cranial cruciate ligament of dogs
Authors: Hayashi Kei , Frank Joseph D. , Hao Zhengling , Schamberger Gwenn M. , Markel Mark D. , Manley Paul A. , Muir Peter
Published: December 2005

Objective—To determine fibroblast viability, assess development of apoptosis, and evaluate tissue hypoxia via histochemical, in-situ hybridization, or immunohistochemical staining in ruptured and intact cranial cruciate ligaments (CCLs) of dogs.

Animals—32 dogs with ruptured CCLs, and 8 aged and 19 young dogs with intact CCLs.

Procedure—Markers of cell viability (lactate dehydrogenase [LDH]), apoptosis (terminal deoxynucleatidyl transferase-mediated deoxyuridine triphosphate-nick end labeling [TUNEL] method), and hypoxia (hypoxiainducible factor-1α [HIF-1α] monoclonal antibody) were applied to CCL specimens; positive cells were assessed objectively (LDH) and subjectively (TUNEL and HIF-1α) in the main axial tissue component (core) and synovial intima and subintima (epiligamentous tissue).

Results—Viable fibroblasts were seen in all intact and ruptured CCLs. More nonviable cells were found in the core regions of ruptured CCLs and intact CCLs of young dogs than in the epiligamentous regions. Number of nonviable cells in the core region of ruptured CCLs was greater than that in intact CCLs of young and aged dogs, whereas the number in the epiligamentous region was similar in all specimens. The TUNEL and HIF-1αstaining was only found in the epiligamentous region of ruptured CCLs.

Conclusions and Clinical Relevance—Ruptured CCLs contained a high number of nonviable cells but not a great number of apoptotic cells. Repair processes in the epiligamentous region of the CCL include a metabolic response to hypoxia, suggesting that necrosis of ligament fibroblasts and transformation of surviving cells to a spheroid phenotype may be a response to hypoxia cause by microinjury or inadequate blood flow. (Am J Vet Res2003;64:1010–1016)
Seasonal changes in plasma concentrations of cecum-derived amines in clinically normal ponies and ponies predisposed to laminitis
Authors: Bailey Simon R. , Katz Lisa M. , Berhane Yoel , Samuels Tim , Brauvere Nicholas De , Marr Celia M. , Elliott Jonathan
Published: December 2005

Objective—To measure concentrations of amines formed in the cecum of clinically normal ponies, determine amine concentrations in plasma samples collected in spring and winter, and compare concentrations of amines and serotonin in plasma samples obtained from clinically normal ponies and ponies predisposed to laminitis.

Sample Population—Cecal contents obtained from 10 ponies euthanatized at an abattoir and blood samples obtained from 42 adult ponies.

Procedure—Cecal contents were assayed for amines by high-performance liquid chromatography (HPLC). Blood samples were collected at various times of the year from 20 ponies predisposed to acute laminitis and 22 clinically normal ponies. Plasma serotonin concentration was measured by HPLC, and tryptamine (TRP), tyramine (TYR), phenylethylamine (PEA), and isoamylamine (IAA) were measured by liquid chromatography- mass spectrometry.

Results—15 amines were identified in cecal contents. Plasma TRP, TYR, PEA, and IAA concentrations ranged from 10pM to 100nM in both groups of ponies. Plasma concentrations of serotonin or other amines did not differ between clinically normal ponies and those predisposed to laminitis; however, significantly higher concentrations of TRP, PEA, and IAA were found in samples obtained in the spring, compared with winter samples.

Conclusions and Clinical Relevance—Various amines are found in the cecum of ponies, several of which can be detected in the plasma. Concentrations increase significantly in the spring and may reach concentrations close to the threshold for causing vasoconstriction. Release of amines from the cecum into the systemic circulation may contribute to hemodynamic disturbances in horses and ponies with acute laminitis. (Am J Vet Res2003;64:1132–1138)
Serum concentrations of pepsinogen A in healthy dogs after food deprivation and after feeding
Authors: Suchodolski Jan S. , Steiner Jörg M. , Ruaux Craig G. , Williams David A.
Published: December 2005

Objective—To develop and validate an ELISA for
measurement of serum canine pepsinogen A (cPG A)
as a diagnostic marker of gastric disorders in dogs
and to measure serum cPG A in healthy dogs after
food deprivation and after feeding.

Sample Population—Sera from 72 healthy dogs.

Procedure—A sandwich ELISA was developed and
validated. The reference range for serum concentrations
of cPG A was determined in 64 healthy dogs.
Postprandial changes in serum concentrations of cPG
A were evaluated in 8 healthy dogs.

Results—Assay sensitivity was 18 µg/L, and the maximum
detectable concentration was 1,080 µg/L. The
observed-to-expected ratio (O:E) for 3 serial dilutions
of 3 serum samples ranged from 69.3 to 104.1%. The
O:E for 3 serum samples spiked with 8 concentrations
of cPG A ranged from 58.8 to 120.4%.
Coefficients of variation for intra- and interassay variability
of 3 serum samples ranged from 7.6 to 11.9%
and from 10.1 to 13.1%, respectively. Mean ± SD
serum concentration of cPG A in healthy dogs was
63.8 ± 31.0 µg/L and the reference range was 18 to
129 µg/L. Significant increases in serum concentrations
of cPG A were observed between 1 and 7 hours
after feeding.

Conclusions and Clinical Relevance—The ELISA for
measuring cPG A was sufficiently sensitive, linear,
accurate, precise, and reproducible for clinical use.
Serum concentrations of cPG A increase substantially
after feeding, which should be taken into account
when conducting clinical studies. (Am J Vet Res 2003;64:1146–1150)
Effect of oral administration of low doses of pentobarbital on the induction of cytochrome P450 isoforms and cytochrome P450-mediated reactions in immature Beagles
Authors: Kawalek Joseph C. , Howard Karyn D. , Farrell Dorothy E. , Derr Janice , Cope Carol V. , Jackson Jean D. , Myers Michael J.
Published: December 2005

Objective—To determine the effect of oral administration of low doses of pentobarbital on cytochrome P450 (CYP) isoforms and CYP-mediated reactions in immature Beagles.

Animals—42 immature (12-week-old) Beagles.

Procedure—Dogs were grouped and treated orally as follows for 8 weeks: low-dose pentobarbital (50 µg/d; 4 males, 4 females), mid-dose pentobarbital (150 µg/d; 4 males, 4 females), high-dose pentobarbital (500 µg/d; 4 males, 4 females), positive-pentobarbital control (10 mg/kg/d; 2 males, 2 females), positivephenobarbital control (10 mg/kg/d; 2 males, 2 females), and negative control (saline [0.9% NaCl] solution; 5 males, 5 females). Serum biochemical and hematologic values were monitored. On necropsy examination, organ weights were determined, and histologic evaluation of tissue sections of liver, kidney, small intestine, testes, epididymis, and ovaries was performed. Hepatic and intestinal drug-metabolizing enzyme activities were measured, and relative amounts of CYP isoforms were determined by western blot analysis.

Results—The amount of a hepatic CYP2A-related isoform in dogs from the high-dose pentobarbital treatment group was twice that of dogs from the negative control group. CYP2C was not detectable in small intestinal mucosa of dogs from the negative control group; measurable amounts of CYP2C were found in dogs from the various (low-, mid-, and high-dose) pentobarbital treatment groups and from positive-pentobarbital and positive phenobarbital control groups. Several CYP-mediated reactions increased in a dosedependent manner. The lowest calculated effective dose of pentobarbital ranged from 200 to 450 µg/d.

Conclusions and Clinical Relevance—Several CYP isoforms and their associated reactions were induced in dogs by oral administration of low amounts of pentobarbital. (Am J Vet Res2003;64:1167–1175)
Evaluation of survival of Actinobacillus pleuropneumoniae and Haemophilus parasuis in four liquid media and two swab specimen transport systems
Authors: Río Maria L. del , Gutiérrez Beatris , Gutiérrez Cesar B. , Monter Jose L. , Ferri Elias F. Rodríguez
Published: December 2005

Objective—To determine duration and rates of recovery
of Actinobacillus pleuropneumoniae and
Haemophilus parasuis from 4 liquid media and 2 swab
specimen transport systems and compare findings
with those of Escherichia coli.

Sample Population—One strain each of A pleuropneumoniae(
biovar 1, serotype 1), H parasuis (serovar
5), and E coli (serotype O149:K91:H19).

Procedure—Strains were incubated in brain heart
infusion broth supplemented with horse serum and
other nutrients or in horse serum alone, with and
without nicotinamide-adenine dinucleotide in both
instances, for 150 days at 4°C or room temperature
(21°C). Similarly, strains were tested in Stuart and
Amies transport systems after storage at room temperature
for 8 days.

Results—Colony counts greater than those of the initial
inoculum were observed after incubation in horse
serum for A pleuropneumoniae but not for H parasuis.
Overall, incubation at 4°C in the 4 liquid media
resulted in longer recovery duration and higher rates
than at room temperature. Culture of H parasuis
resulted in lower recovery rates and shorter durations
of recovery than culture of A pleuropneumoniae,
except for culture in horse serum. Haemophilus parasuis
survived longer than A pleuropneumoniae in the
transport systems, and all organisms survived longer
in the Amies system.

Conclusions and Clinical Relevance—Survival of A
pleuropneumoniae and H parasuis indicated that horse
serum prolongs survivability, which may result in exposure
of more animals during a prolonged period. The
Amies system might be a good choice for collection of
clinical samples from animals, especially for recovery
of H parasuis. (Am J Vet Res 2003;64:1176–1180)
Determination of calcium fractionation in dogs with chronic renal failure
Authors: Schenck Patricia A. , Chew Dennis J.
Published: December 2005

Objective—To determine concentrations of calcium (total [tCa], ionized [iCa], protein-bound [pCa], and complexed [cCa]) in dogs with chronic renal failure (CRF).

Animals—23 dogs with CRF.

Procedure—Serum calcium was fractionated by use of a micropartition system. Total calcium and iCa concentrations and pH were measured in unfractionated serum, and tCa concentration was measured in the ultrafiltrate. The pCa fraction was calculated by subtracting tCa of the ultrafiltrate from tCa concentration of unfractionated serum. The iCa concentration in unfractionated serum was subtracted from tCa concentration in the ultrafiltrate to determine the concentration of cCa.

Results—Concentrations of tCa, iCa, pCa, and cCa had wide ranges among dogs with CRF. Dogs with significantly low tCa concentration (7.70 ± 1.73 mg/dL) had cCa concentration (0.76 ± 0.38 mg/dL) within reference range, whereas dogs with reference range to high tCa concentration (10.85 ± 1.13 mg/dL) had significantly high cCa concentration (2.62 ± 1.04 mg/dL). There was no significant difference in iCa or pCa concentrations between groups.

Conclusions and Clinical Relevance—Concentrations of tCa, iCa, cCa, and pCa varied widely in dogs with CRF. Overall, cCa concentration was high, although subpopulations differed in cCa and tCa concentrations. Differences in tCa concentration were primarily attributable to differences in cCa fraction. (Am J Vet Res2003;64:1181–1184)
Effect of induced unilateral synovitis of distal intertarsal and tarsometatarsal joints on sagittal plane kinematics and kinetics of trotting horses
Authors: Khumsap Siriporn , Lanovaz Joel L. , Rosenstein Diana S. , Byron Christopher , Clayton Hilary M.
Published: December 2005

Objective—To study the effect of unilateral synovitis in the distal intertarsal and tarsometatarsal joints on locomotion, including the compensating effects within and between limbs.

Animals—4 clinically normal horses.

Procedure—Gait analyses including kinematics, force plate, and inverse dynamic analysis were performed at the trot before lameness, after which synovitis was induced by injecting endotoxin into the right distal intertarsal and tarsometatarsal joints. Gait analyses were repeated 24 to 30 hours later during lameness. Differences between the stride variables during the 2 conditions (lame and sound) were identified.

Results—Tarsal joint range of motion, peak vertical force, and vertical impulse were decreased during lameness. Mechanical deficits included a decrease in negative work performed by the tarsal extensors during the early stance phase and a decrease in positive work by the tarsal extensors during push off. No compensatory changes in work were performed by other joints within the lame hind limb during the stance phase. Vertical impulse in the diagonal forelimb decreased, but there were no significant changes in forces or impulses in the ipsilateral forelimb or contralateral hind limb.

Conclusions and Clinical Relevance—Results indicate that horses are able to manage mild, unilateral hind limb lameness by reducing the airborne phase of the stride rather than by increased loading of the compensating limbs. (Am J Vet Res2003;64:1491–1495)
In vitro effects of Actinobacillus pleuropneumoniae on inducible nitric oxide synthase and cyclooxygenase-2 in porcine alveolar macrophages
Authors: Cho Wan-Seob , Chae Chanhee
Published: December 2005

Objective—To determine the amount of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) activity in alveolar macrophages in response toActinobacillus pleuropneumoniae(APP) by determining nitric oxide (NO) and prostaglandin E2(PGE2) concentrations.

Sample Population—Freshly isolated porcine alveolar macrophages.

Procedure—Alveolar macrophages were incubated for 48 hours with APP (1 × 104colony-forming units/mL), interleukin-1β (IL-1β; 5 U/mL), tumor necrosis factor-α (TNF-α; 500 U/mL), interferon-γ (IFN-γ; 100 U/mL), or lipopolysaccharide (LPS; 10 µg/mL). In a second experiment, alveolar macrophages were incubated with fresh medium (negative control), APP alone, or APP with 1 of the following: IL-1β, TNF-α, or IFN-γ. In a third experiment, alveolar macrophages were incubated with fresh medium (negative control), LPS (positive control), APP alone, or APP with 1 of the following: an iNOS inhibitor (3.3µM), a COX-2 inhibitor (10µM); or both the iNOS and COX-2 inhibitors. Supernatant was obtained at 0, 3, 6, 9, 12, 24, and 48 hours after treatment for determination of NO and PGE2production.

Results—The addition of APP to alveolar macrophages resulted in significant increases in NO and PGE2production. The addition of APP and IFN-γ synergistically induced NO production. Inhibition of iNOS and COX-2 decreased NO and PGE2production, respectively.

Conclusions and Clinical Relevance—In vitro activation of alveolar macrophages by APP results in increased production of NO and PGE2. Nitric oxide and PGE2production appears to be largely dependent on iNOS and COX-2 activity. Pharmacologic modulation of iNOS and COX-2 activity may represent a therapeutic target for pigs with pleuropneumonia. (Am J Vet Res2003;64:1514–1518)
Effects of hydrochloric, valeric, and other volatile fatty acids on pathogenesis of ulcers in the nonglandular portion of the stomach of horses
Authors: Nadeau Jenifer A. , Andrews Frank M. , Patton Clark S. , Argenzio Robert A. , Mathew Alan G. , Saxton Arnold M.
Published: December 2005

Objective—To identify in vitro effects of hydrochloric acid, valeric acid, and other volatile fatty acids (VFAs) on the pathogenesis of ulcers in the nonglandular portion of the equine stomach.

Sample Population—Gastric tissues from 13 adult horses.

Procedure—Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance and conductance calculated after tissues were bathed in normal Ringer's solution (NRS) or NRS and hydrochloric, valeric, acetic, propionic, and butyric acids. Treated tissues were examined histologically.

Results—Incubation in 60mM valeric acid at pH ≤ 7.0 abruptly and irreversibly abolished Isc, which was followed by a slower decrease in resistance and an increase in conductance. Incubation in 60mM acetic, propionic, and butyric acids and, to a lesser extent, hydrochloric acid at pH ≤ 7.0 significantly decreased Isc, which was followed by an increase in resistance and a decrease in conductance.

Conclusions and Clinical Relevance—Incubation in valeric acid at pH ≤ 7.0 caused a dramatic decrease in mucosal barrier function in the nonglandular portion of the stomach. Changes in barrier function attributable to exposure to valeric acid were associated with histopathologic evidence of cellular swelling in all layers of the nonglandular mucosa. Because of its high lipid solubility, valeric acid penetrates the nonglandular gastric mucosa, resulting in inhibition of sodium transport and cellular swelling. Valeric acid and other VFAs in gastric contents may contribute to the pathogenesis of ulcers in the nonglandular portion of the stomach of horses. (Am J Vet Res2003;64:413–417)