bluuebunny/crossref_metadata_2025 huggingface dataset:
Asynchronous Parallel Electromagnetic Transient Simulation of Large Scale Power System
Authors: Chen Gesong , Zhou Xiaoxin
Published: December 2005

An asynchronous parallel electromagnetic simulation method for large scale power system is developed, in which the original system is divided into two subsystems, A and B. Subsystem A is the local system including the disturbance source and any devices that should be simulated in details. Subsystem B is the external system consisting of all the other part of the system. The time domain digital simulation of subsystem A and B are executed by two independent processes with different time-steps. Signal transmission between A and B is implemented at each time step by a series of time varying Norton equivalent circuits and equivalent voltage sources. Because the digital simulation for subsystem A and B are processed in parallel, and simulation time of process B lags that of process A, so its called asynchronous parallel electromagnetic simulation method. The basic principle, implementation procedure and error analysis of this new method are discussed, computer coding is also implemented in one version of EMTP program. Practical power system simulation and other application with the new method are also presented.
Application of Open Agent Architecture and Data Mining Techniques to Transformer Condition Assessment System
Authors: Wu Lizeng , Yongli Zhu , Yuan Jinsha , Li Xueyu
Published: December 2005

The framework of transformer condition assessment system is proposed in this paper through mainly using data warehouse techniques, data mining techniques, and Open Agent Architecture. In this system, a data warehouse is used to collect transformers testing data, a multi-agent system is used to design the framework of the software, and data mining techniques are used to evaluate transformers conditions. The present framework is open and flexible, so the objective system is easy to be developed and maintained. The system can support transformers condition-based maintenance to reduce electric utilitys cost.Because the condition of a transformer depends on its design, present and historical operating data, and relates to its installation environment, load amounts, and so on, it is necessary to integrate all above information to evaluate transformers condition. However, the off-line testing results, operational data, fault records and weather conditions have been stored in different systems, so finding an effective method to utilize all this information for condition assessment is difficult. Therefore, a data warehouse has been set up to integrate all of the above data, and some data mining techniques have been used to find the pattern and trend of the condition of a transformer. Then whether it is healthy can be determined. In order to make the system open and flexible, Open Agent Architecture (OAA) is employed to compose the multi-agent system. Seven application agents are designed to evaluate transformers conditions synthetically. The Grey correlation method, grey theory prediction model GM(1,1), Bayesian network classifier and Bayesian network are employed in the agents.
Optimisation of Safety and Reliability of Captive Power Plant Maintenance Scheduling Using Genetic Algorithm and Simulated Annealing
Authors: Mohanta Dusmanta Kumar , Sadhu Pradip Kumar , Chakrabarti Rupendranath
Published: December 2005

The objective of this paper is to optimize maintenance scheduling of generating units of a captive thermal plant using intelligent optimization techniques such as genetic algorithm (GA) and simulated annealing (SA). A multi-class maintenance scheduling has been considered to incorporate statutory safety regulations for maintenance of boilers, turbines and generators. Such multi-class maintenance scheduling in terms of mathematical formulations necessitates a planning horizon of five years compared to the conventional one to two year horizon. As the utilities catered by captive power plants are very sensitive to power failure, the reliability of power supply has been evaluated by loss of load probability (LOLP) index. The significant contribution of this paper is to evaluate confidence intervals of LOLP instead of conventional point estimate of LOLP. A point-estimate of LOLP uses expected values and provides no information about the range of values over which LOLP may vary. Some variations from optimum schedules are anticipated while executing maintenance schedules due to different real-life unforeseen exigencies. Such exigencies are considered in terms of near-optimum schedules obtained from SA during the final stages of convergence. LOLP evaluated from such sub-optimum schedules forms the basis to treat LOLP as a random variable for subsequent evaluation of confidence intervals. Case studies pertaining to a captive power plant for an aluminium smelter corroborate that the schedules obtained from two optimization techniques yield the same optimum schedule and thus the efficacy of the proposed algorithm is validated. Also the interval of confidence for LOLP denotes the possible risk in a quantified manner and it is of immense use from perspective of captive power plants intended for quality power.
Utilization of Controlled Shunt Reactor in a 400KV Interconnected Network
Authors: SISHTLA VENKATA NATARAJA JITHIN SUNDAR , M Reshmi
Published: December 2005

Fixed shunt reactors are traditionally used in long distance EHV and UHV lines to reduce Ferranti over voltages and over voltages that arise due to load rejection. A new equipment called Controlled shunt reactor (CSR) has been developed [3] and [4]. Detailed load flow and voltage stability analysis on a typical 400KV interconnected network prove that replacement of fixed shunt reactors with CSR is beneficial. This study report is an attempt to justify and quantify the economic and technical benefits of CSR in a 400KV system
Duration Curve Approach for Managing Uncertainty of Renewable Generation While Dispatching a Mixed Generation Portfolio
Authors: Bhandari Narad Muni , Galloway Stuart , Burt Graeme , McDonald Jim
Published: December 2005

Many analytical solution methods are incapable of dealing with modern power system planning, operation and control problems due to various uncertainties involved in the system. Generation output from most of renewable energy (RE) sources is uncertain which varies with time. Therefore, appropriate solution methods need to be considered in light of the uncertainty of RE generation. In this paper, a generation duration curve approach has been presented in order to handle the uncertainty of RE generation output while solving a combined dispatch problem of fossil fuel (FF) units and RE sources. A cost minimisation scheduling problem of FF units along with forecasted quantities of RE sources is formulated and solved considering the probability of meeting or exceeding anticipated shortfalls of RE outputs. Due to the complexity of the problem a genetic algorithm (GA) based solution approach is considered for solving the problem. A test problem with five FF units and three RE sources is formulated and solved under various considerations. It is demonstrated that the combined operation of FF units with RE sources gives better results, which can also manage uncertainty associated with RE generation outputs.
Optimal Placement of SVC for Static and Dynamic Voltage Security Enhancement
Authors: Verma M. K. , Srivastava S.C.
Published: December 2005

This paper presents a sensitivity based approach to determine optimal location of Static VAR Compensator (SVC) for voltage security enhancement. The proposed approach of SVC placement computes sensitivity of system loading factor with respect to reactive power generation, derived from reactive power balance equation. This sensitivity factor has been termed as Bus Static Participation Factor (BSPF). The sensitivity of the most critical eigen value with respect to bus voltage magnitude has been considered as Bus Dynamic Participation Factor (BDPF). BSPF and BDPF have been combined to obtain Bus Hybrid Participation Factor (BHPF), which have been computed for the system intact case and critical contingency cases and used for selecting the optimal site for the SVC installation. The effectiveness of the proposed approach of SVC placement has been validated on a practical 75-bus Indian system with respect to enhancement of the static as well as dynamic voltage stability margins.
A Simulated Annealing Based Hybrid Optimization Approach for a Fuzzy Modelled Unit Commitment Problem
Authors: Albert Victoire Aruldoss T , Jeyakumar Ebenezer A
Published: December 2005

This article presents a solution model for the unit commitment problem (UCP) using fuzzy logic to address uncertainties in the problem. Hybrid simulated annealing (SA), particle swarm optimization (PSO) and sequential quadratic programming (SQP) technique (hybrid SA-PSO-SQP) is used to schedule the generating units based on the fuzzy logic decisions. The fitness function for the hybrid SA-PSO-SQP is formulated by combining the objective function of UCP and a penalty calculated from the fuzzy logic decisions. Fuzzy decisions are made based on the statistics of the load demand error and spinning reserve maintained at each hour. SA is used to solve the combinatorial sub-problem of the UCP. An improved random perturbation scheme and a simple method for generating initial feasible commitment schedule are proposed for the SA method. The non-linear programming sub-problem of the UCP is solved using the hybrid PSO-SQP technique. Simulation results on a practical Neyveli Thermal Power Station system (NTPS) in India and several example systems validate, the presented UCP model is reasonable by ensuring quality solution with sufficient level of spinning reserve throughout the scheduling horizon for secure operation of the system.
Some Issues Related to Power Generation Using Wind Energy Conversion Systems: An Overview
Authors: Bansal Dr. R. C. , Zobaa Dr. Ahmed F , Saket Dr. R. K.
Published: December 2005

Design and successful operation of wind energy conversion systems (WECs) is a very complex task and requires the skills of many interdisciplinary skills, e.g., civil, mechanical, electrical and electronics, geography, aerospace, environmental etc. Performance of WECs depends upon subsystems like wind turbine (aerodynamic), gears (mechanical), generator (electrical); whereas the availability of wind resources are governed by the climatic conditions of the region concerned for which wind survey is extremely important to exploit wind energy. This paper presents a number of issues related to the power generation from WECs e.g. factors affecting wind power, their classification, choice of generators, main design considerations in wind turbine design, problems related with grid connections, wind-diesel autonomous hybrid power systems, reactive power control of wind system, environmental aspects of power generation, economics of wind power generation, and latest trend of wind power generation from off shore sites.
Multi-Objective VAR Dispatch Using Particle Swarm Optimization
Authors: Durairaj Mr. S. , Kannan Dr. P.S. , Devaraj Dr. D.
Published: December 2005

Reactive Power Dispatch (RPD) is one of the important tasks in the operation and control of power system. The objective is to apply Particle Swarm Optimization (PSO) algorithm for arriving optimal settings of RPD problem control variables. Incorporation of PSO as a derivative free optimization technique in solving RPD problem significantly relieves the assumptions imposed on the optimized objective functions. The proposed algorithm has been applied to find the optimal reactive power control variables in IEEE 30-bus system and in a practical Indian power system with different objectives that reflect loss minimization, voltage profile improvement and voltage stability enhancement. The results of this approach have been compared with the results of Genetic Algorithm (GA). The results are promising and show the effectiveness and robustness of the proposed approach.
Adaptive Fuzzy PI-Sliding Mode Controller for Induction Motor Speed Control
Authors: Hazzab Abdeldjebar , Ismail Khalil Bousserhane , Kamli Mokhtar , Rahli Mostefa
Published: December 2005

In this paper, an adaptive fuzzy PI-sliding mode control (AFPISMC) is proposed for induction motor (IM) speed control. First, an adaptive sliding-mode controller (APISMC) with a proportional plus integral equivalent control action is investigated, in which a simple adaptive algorithm is utilized for generalised soft-switching parameters. The proposed control design uses the fuzzy logic techniques to dynamically control parameter settings of the SMC equivalent control action. The theoretical analyses for the proposed fuzzy PI-sliding-mode controller are described in detail. Simulated results show that the proposed controller provides high-performance dynamic characteristics and is robust with regard to plant parameter variations and external load disturbance.
Comparison of Coal-fired and Natural Gas-fired Power Plants as Economically Viable and Ecologically Sustainable Power Generation Systems
Authors: Sampattagul Sate , Kato Seizo , Kiatsiriroat Tanongkiat , Maruyama Naoki , Nishimura Akira
Published: December 2005

To achieve a sustainable power generation industry it is necessary to study the environmental impacts and economic costs of all aspects of a power generation plants lifecycle - from mining to electricity distribution, and, ultimately, decommission (from cradle to grave). One key component in improving and maintaining quality of life for consumers is the application of the Green Productivity Index (GPI) in order to evaluate the related factors of Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). The goal of this research is to appraise the efficacy of decision-making tools in accurately assessing the potential results of green improvements to coal-fired and natural gas-fired power plants in both ecological and economic terms. The recently developed Numerical Eco-load Total Standardization (LCA-NETS) evaluates environmental impacts by identifying and quantifying input energy and output waste released to the environment throughout the life cycle of a power plant. Environmental impacts caused by global and regional environmental issues are numerically calculated in the units of NETS. Environmental assessment tools such as LCA, LCC and GPI can be used to improve the environmental friendliness of electricity generation by demonstrating the future sustainability of green power generation plants and their contribution to the quality of life of consumer.
Milks and Milk Concentrates: Surface Tension Measurement
Authors: Williams Anna M , Jones J.R. , Paterson A.H.J. , Pearce D.L.
Published: December 2005

Surface tension is an important property of milk concentrates because it affects atomisation in spray drying. A Krüss tensiometer and Wilhelmy plate were used to measure surface tension. Skim milk and whole milk were tested at a range of solids concentrations and were compared with the surface tension of standard and reconstituted milks. It was found that surface tension was affected more by temperature than by fat content or solids concentration. The surface tensions for concentrates correspond to published values for standard milks below 60°C, but above 60°C, the surface tension increases markedly, which can be attributed to changes in the milk chemistry. The difficulty associated with using the Wilhelmy plate method is the time taken to perform each measurement, which allows a skin to form and reduces the accuracy of the measurements.
Fouling of Milk on Heat Transfer Surface with and without the Addition of Bacillus stearothermophilus - A Laboratory Study
Authors: Yoo Jinah , Chen Xiao Dong , Bansal Bipan
Published: December 2005

Fouling of heat transfer surfaces during milk processing is a major problem for dairy industry. In the current work, the nature and extent of milk fouling with and without the addition of Bacillus stearothermophilus in the feed solutions have been studied. A fouling detection system based on electric conductivity measurements has been used. The coresponding thermal resistance of the deposit layer has also been worked out. The fouling deposits have been analysed visually as well as with a scanning electron microscope (SEM). The results show significant variation in the fouling patterns with and without the large presence of bacteria in the flowing medium.
A Study on the Preservation of Vegetable Juices Using Quasi-Nanoscale Silver Particles
Authors: Zhang Min , Duan Zhen-hua , Shan Wei , An Jian-shen
Published: December 2005

The effects of quasi-nanoscale silver on preservation of both tomato juice and mixed juice from tomato and carrot were studied in this paper. The effective dose of quasi-nanoscale silver on tomato juice was found to be 0.1ppm, but when the same dose was applied to the mixed juice, heating at 100 deg.C for 5min was necessary. Furthermore, the effects of quasi-nanoscale silver combined with nipagin A on preservation of both tomato juice and the mixed juice from tomato and carrot were also investigated. The optimum combination pattern of quasi-nanoscale silver and nipagin A on both tomato juice and the mixed juice was found to be 0.04ppm of quasi-nanoscale silver and 200ppm of nipagin A. When this combination pattern was used in preservation of the mixed juice, it was again needed to heat the mixed juice at 100 deg.C for 5 min to be effective.
Scaling Up of Osmotic Distillation from Laboratory to Pilot Plant for Concentration of Fruit Juices
Authors: Bui A. V. , Nguyen H. M.
Published: December 2005

A step-by-step procedure for scaling up of an osmotic distillation system from laboratory to pilot plant is discussed. The newly built pilot scale OD system featured a flexibility of using 1 or 2 hollow fibre modules at a time to suit the concentration demands. Three types of hollow fibres were tested on the new system. Pilot trials for OD concentration of apple, grape juices and freeze concentrated (FC) grape juice were successfully carried out to achieve a final concentration up to 65°Brix with fluxes ranging from 2.4 to 0.69kg.m-2.h-1 depending on the fibre types and the operating conditions. Cascade effect was also employed to deal with high viscosity to achieve high concentration. The obtained pilot OD fluxes were comparable to the ones obtained in the lab under similar conditions, and they fitted well with the developed models. Sensory evaluation indicated that OD well preserved the quality attributes of the fruit juices.
Effect of High Pressure and Irradiation Treatments on Hydration Characteristics of Navy Beans
Authors: Ramaswamy Raghupathy , Balasubramaniam V. M. , Sastry S.K.
Published: December 2005

The effects of high-pressure (33, 400 and 700 MPa for 3 min at 24 and 55°C) and irradiation (2 and 5 kGy) pre-treatments on hydration behavior of navy beans were studied by soaking the treated beans in water (1:2, w/w) at 24 and 55°C. Beans hydrated at 55°C and allowed to cool by natural convection served as the control. Treating beans under moderate pressure (33 MPa) resulted in high initial moisture uptake (0.59 to 1.02 kg/kg dry mass) and reduced loss of soluble materials. The final moisture content after three hours of soaking was the highest in irradiated beans (5 kGy) followed by HPP (33 MPa; 3 min; 55°C). Within the experimental range of the study, Pelegs model was found to satisfactorily describe the rate of water absorption of navy beans. Peleg's constant K1 had an inverse correlation with soaking temperature whereas K2 increased with increases in temperature and pressure.
Working Time and Employment Under Uncertainty
Authors: Chen Yu-Fu , Funke Michael
Published: December 2005

The standard literature on working time has modelled the decisions of firms in a deterministic framework in which firms can choose between employment and overtime (given mandated standard hours). Contrary to this approach, we consider the impact of uncertainty and real options on the decision of working time and examine the determinants of employment and hours in a stochastic framework. A number of simulation exercises to illustrate the workings of the model are also undertaken.
Household Income Dynamics in Two Transition Economies
Authors: Lokshin Michael , Ravallion Martin
Published: December 2005

We test for the existence of poverty traps and distribution-dependent growth using a nonlinear dynamic panel data model of household incomes allowing for endogenous attrition. Our estimates for Hungary and Russia in the 1990s reveal significant nonlinearity in the dynamics, consistent with the claim that income inequality attenuates growth in mean income. However, we do not find evidence of a threshold effect at low incomes, as postulated by models of dynamic poverty traps. Our results indicate that households generally bounce back from transient shocks, though we find that the adjustment process is slower for households who are poorer in steady state.
Staff Use of E-Learning and Graduate Competencies for the Knowledge Economy: A Study of the Misalignment between Rhetoric and Practice
Authors: Souleles Nicos
Published: December 2005

E-learning is part of the wider debate on the changing role of higher education (HE). It is associated with the agenda on graduate employability and competencies for the knowledge economy (KE). Policy documents make explicit that participation in the KE is congruent with the acquisition of meta-skills. The role of HE is to provide for these competencies and e-learning is presented as assisting this objective. A primary prerequisite, however, is appropriate staff development. This qualitative study examines the relationship between the rhetoric and the practice of e-learning, and argues that issues associated with professional development exist at both institute and staff levels.
Serum concentrations of acute-phase proteins in dogs with leishmaniosis during short-term treatment
Authors: Martínez-Subiela Silvia , Bernal Luis J. , Cerón José J.
Published: December 2005

Objective—To evaluate changes in serum concentrations of acute-phase proteins in dogs with leishmaniosis during short-term therapy in accordance with 2 treatment protocols and determine whether concentrations of acute-phase proteins could be used to monitor the initial response of dogs to treatment.

Animals—12 dogs naturally infected withLeishmania infantum.

Procedure—Dogs were allocated into 2 groups. Dogs of group 1 were treated by use of meglumine antimonate (100 mg/kg, SC, q 24 h) administered concurrently with allopurinol (15 mg/kg, PO, q 12 h) for 20 days and then with allopurinol alone at the same dosage for the subsequent 30 days. Dogs of group 2 were treated by administration of allopurinol alone (15 mg/kg, PO, q 12 h) for 60 days). Blood samples were obtained before and during treatment for measurement of serum concentrations of acute-phase proteins and determination of CBC counts, serum biochemical analyses, and electropherograms.

Results—All dogs evaluated in the study had increased concentrations of C-reactive protein, haptoglobin, and ceruloplasmin at the time of diagnosis of leishmaniosis. Mean concentration of serum amyloid A before treatment was also increased, but some of the dogs had concentrations of serum amyloid A that were within the reference range. Concentrations of C-reactive protein and ceruloplasmin decreased significantly in all dogs at the end of the study period.

Conclusions and Clinical Relevance—Measurement of concentrations of selected acute-phase proteins, such as C-reactive protein or ceruloplasmin, could be used to evaluate the initial response of dogs with leishmaniosis to treatment. (Am J Vet Res2003;64:102–1026)
Geometric symmetry of the solar surface of hooves of Thoroughbred racehorses
Authors: Roland Elizabeth , Stover Susan M. , Hull Maury L. , Dorsch Katie
Published: December 2005

Objective—To define a 3-dimensional (3-D) coordinate system with clear definitions of origins and axes relative to hoof anatomic features and determine whether solar surfaces of Thoroughbred racehorse hooves have geometric asymmetry in the mediolateral and dorsopalmar directions.

Sample Population—Left forelimb hooves from 20 Thoroughbred racehorse cadavers.

Procedure—A right-handed 3-D coordinate axes system centered on the collateral sulci was defined for the left front hoof. Orthogonal distances of anatomic features from the dorsopalmar axis and the plane coincident with the ground were measured and compared between medial and lateral sides and between dorsal and palmar regions of the hoof.

Results—The hoof was wider and had a greater radius laterally than medially. The most distal part of the lateral bar of the frog was further from the dorsopalmar axis than that of the medial bar. Overall, mediolateral asymmetries in depth were not observed. The sole at the perimeter was deeper medially in the dorsal part of the hoof and laterally in the palmar part, with depth overall being greater palmarly than dorsally. Most features had dorsopalmar asymmetry.

Conclusions and Clinical Relevance—When the angle bisected by the collateral sulci is used to determine the dorsopalmar axis of the hoof, most central structures (bars and collateral sulci) have mediolateral symmetry. However, the hoof wall and sole have some mediolateral asymmetries and most structures have dorsopalmar asymmetry. These findings may assist the development of devices for attachment to hooves and studies of the interaction of hooves with bearing surfaces. (Am J Vet Res2003;64:1030–1039)
Comparison of plasma and interstitial fluid concentrations of doxycycline and meropenem following constant rate intravenous infusion in dogs
Authors: Bidgood Tara L. , Papich Mark G.
Published: December 2005

Objective—To compare plasma (total and unbound) and interstitial fluid (ISF) concentrations of doxycycline and meropenem in dogs following constant rate IV infusion of each drug.

Animals—6 adult Beagles.

Procedure—Dogs were given a loading dose of doxycycline and meropenem followed by a constant rate IV infusion of each drug to maintain an 8-hour steady state concentration. Interstitial fluid was collected with an ultrafiltration device. Plasma and ISF were analyzed by high performance liquid chromatography. Protein binding and lipophilicity were determined. Plasma data were analyzed by use of compartmental methods.

Results—Compared with meropenem, doxycycline had higher protein binding (11.87% [previously published value] vs 91.75 ± 0.63%) and lipophilicity (partition coefficients, 0.02 ± 0.01 vs 0.68 ± 0.05). A significant difference was found between ISF and plasma total doxycycline concentrations. No significant difference was found between ISF and plasma unbound doxycycline concentrations. Concentrations of meropenem in ISF and plasma (total and unbound) were similar. Plasma half-life, volume of distribution, and clearance were 4.56 ± 0.57 hours, 0.65 ± 0.82 L/kg, and 1.66 ± 2.21 mL/min/kg, respectively, for doxycycline and 0.73 ± 0.07 hours, 0.34 ± 0.06 L/kg, and 5.65 ± 2.76 mL/min/kg, respectively, for meropenem. The ISF half-life of doxycycline and meropenem was 4.94 ± 0.67 and 2.31 ± 0.36 hours, respectively.

Conclusions and Clinical Relevance—The extent of protein binding determines distribution of doxycycline and meropenem into ISF. As a result of high protein binding, ISF doxycycline concentrations are lower than plasma total doxycycline concentrations. Concentrations of meropenem in ISF can be predicted from plasma total meropenem concentrations. (Am J Vet Res2003;64:1040–1046)
Antibacterial activity of short hydrophobic and basic-rich peptides
Authors: Chen Po-Wen , Shyu Ching-Ling , Mao Frank C.
Published: December 2005

Objective—To design short and potent analogs of
bovine lactoferricin by use of the concepts of
lipophilic bulk and cationic charge.

Sample Population—5 synthetic peptides of bovine
lactoferricin.

Procedure—Antibacterial peptides were constructed
by synthesizing several decapeptides rich in arginine
and tryptophan. Basic residues of bovine lactoferricin
(bLf 20-29; residues 20 to 29) were modified by substitution
with arginine or lysine and nonbasic residues
were modified by substitution with tryptophan,
phenylalanine, or isoleucine. Synthetic peptides of
bovine lactoferrin (LFB) were designated as LFB-RW
(RRWWWRWRRW), LFB-KW (KKWWWKWKKW),
LFB-RWa (RRWWRRWRRW), LFB-RF (RRFFFRFRRF),
and LFB-RI (RRIIIRWRRI), where R, K, W, F, and
I stand for arginine, lysine, tryptophan, phenylalanine,
and isoleucine, respectively. Peptides were evaluated
by determining their minimum inhibitory concentration
(MIC) and minimum bactericidal concentration
(MBC) against Escherichia coli, Staphylococcus
aureus,and Enterococcus faecalis.

Results—LFB-RW, LFB-KW, and LFB-RWa possessed
equivalent potency as bLf 20-29 against E coli.
LFB-RW and LFB-RWa had a 2-fold increase in
growth-inhibitory and bactericidal activity against
S aureus, compared with bLf 20-29. LFB-RI had the
lowest MIC value against E coli among the peptides
but lost bactericidal activity. LFB-RW and LFB-KW had
stronger bactericidal activities against S aureus or
E faecalis, respectively, as well as E coli than the
other synthetic peptides. LFB-RF also had antibacterial
activity, but this was 2-fold less than that of LFBRW,
as determined by MIC and MBC values.

Conclusions and Clinical Relevance—In construction
of potent antibacterial peptides, inclusion of arginine,
lysine, tryptophan, or isoleucine residues
enhances effectiveness against certain bacteria, as
measured by MIC or MBC values. (Am J Vet Res 2003;64:1088–1092)
Comparison of ultrasonographic characteristics of the gastroduodenal junction during pyloroplasty performed laparoscopically or via conventional abdominal surgery in dogs
Authors: Sánchez-Margallo Francisco M. , Soria-Gálvez Federico , Ezquerra-Calvo Luis J. , Usón-Gargallo Jesús
Published: December 2005

Objective—To evaluate the use of ultrasonography to detect morphologic changes in the pylorus during pyloroplasty performed laparoscopically or via conventional abdominal surgery in dogs.

Animals—10 healthy mixed-breed dogs.

Procedure—Laparoscopic ultrasonography of the pylorus was performed in 5 dogs during laparoscopic pyloroplasty (LP), and ultrasonography of the pylorus was performed in 5 dogs during pyloroplasty via conventional abdominal surgery (CAP group). Appearance and dimensions of the pyloric sphincter were evaluated by use of a 7.5-MHz flexible laparoscopic linear-transducer probe.

Results—Mean ± SD duration of the ultrasonographic procedure was 11 ± 3.04 minutes (range, 6 to 18 minutes). In the CAP group, cross-sectional views of the pylorus revealed significant differences between the overall transverse external diameter, overall craniocaudal external diameter, and transverse diameter of the pyloric lumen. After surgery, the pyloric area was significantly increased. Longitudinal views of the pylorus revealed that width of the pyloric ring was significantly less after surgery. Transverse views of the pylorus for the LP group revealed a significant increase in the transverse diameter and craniocaudal diameter of the pyloric lumen after LP. The pyloric area was also significantly increased after surgery. Longitudinal views of the pylorus revealed that width of the pyloric ring was significantly less after surgery. Transverse diameter of the pyloric lumen was significantly increased after LP.

Conclusions and Clinical Relevance—Analysis of results of this study suggests that ultrasonography is useful for detecting relevant morphologic changes in the pyloric sphincter after pyloroplasty. (Am J Vet Res2003;64:1099–1104)
Effects of monoamines formed in the cecum of horses on equine digital blood vessels and platelets
Authors: Elliott Jonathan , Berhane Yoel , Bailey Simon R.
Published: December 2005

Objective—To determine in vitro vasoactive potency of monoamines formed in the cecum and found in the systemic circulation of horses.

Sample Population—Segments of digital blood vessels obtained from 6 healthy mixed-breed horses and ponies euthanatized at an abattoir and platelets isolated from 4 healthy ponies.

Procedure—Paired rings of digital artery and vein from the same horse were examined, and isometric tension was recorded. Concentration-response curves for tryptamine (TRP), tyramine (TYR), phenylethylamine (PEA), isoamylamine (IAA), and isobutylamine (IBA) were obtained. Vasoconstrictor mechanisms were investigated for TRP and TYR by the use of antagonists. Washed platelets loaded with [3H]-5-hydroxytryptamine (5-HT) were incubated with monoamines; the amount of radioactivity displaced after 30 minutes was estimated.

Results—TRP, TYR, and PEA were potent constrictors of arteries and veins, with TRP and TYR being more potent in veins than arteries. Constrictions induced by TYR were inhibited by benextramine (α-antagonist) and nisoxetine (neuronal-uptake blocker), whereas TRP responses were inhibited by ketanserin (5-HT receptor antagonist). All 5 amines displaced 5-HT from platelets with the order of potency being TYR > TRP > PEA > IAA > IBA.

Conclusions and Clinical Relevance—Amines from the equine cecum cause digital vasoconstriction. The most potent (TRP and TYR) cause selective venoconstriction. Tyrosine activates predominantly α-adrenoceptors through the release of neuronal norepinephrine, whereas TRP activates 5-HT receptors. All amines tested released 5-HT from platelets. Amines formed in the cecum and released into the systemic circulation warrant additional investigation as trigger factors for digital ischemia and subsequent laminitis. (Am J Vet Res2003;64:1124–1131)
In vitro evaluation of biomechanical effects of multiple hemilaminectomies on the canine lumbar vertebral column
Authors: Corse Matthew R. , Renberg Walter C. , Friis E.A.
Published: December 2005

Objective—To conduct an in vitro investigation of the biomechanical characteristics of the canine lumbar spinal column in flexion and extension and measure the destabilizing effects of multiple consecutive unilateral and bilateral hemilaminectomies.

Sample Population—30 isolated multisegmental spinal units (L1-L4) from nonhypochondroplastic dogs weighing 15 to 30 kg.

Procedure—Physically normal and surgically altered spinal specimens were subjected to 4-point bending in flexion and extension to determine effects of multiple consecutive hemilaminectomies on the basis of analysis of test system load-displacement data. Six groups with 5 spinal columns in each were defined on the basis of the following procedures: hemilaminectomy at L2-L3, 2 adjacent hemilaminectomies at L1- L3, 3 adjacent hemilaminectomies at L1-L4, bilateral hemilaminectomies at L2-L3, 2 bilateral hemilaminectomies at L1-L3, and no hemilaminectomy (intact). Spinal stability before and after surgery was determined in all groups. Each group served as its own control for nondestructive testing. Spinal strength was evaluated through destructive testing to determine deformation at failure, strength to failure, and mode of catastrophic failure. The intact group served as the control for destructive testing.

Results—Stability in extreme flexion and extreme extension did not change significantly following any hemilaminectomy procedure. Postoperative stability within the neutral zone was significantly decreased in all groups. Range of motion within the neutral zone was not significantly different from the intact condition in any group.

Conclusions and Clinical Relevance—Multiple hemilaminectomies did not decrease stiffness of the lumbar spinal column during flexion and extension. These results support clinical recommendations regarding multiple consecutive hemilaminectomies in dogs. (Am J Vet Res2003;64:1139–1145)
Evaluation of iohexol clearance used to estimate glomerular filtration rate in clinically normal foals
Authors: Gonda Kathleen C. , Wilcke Jeff R. , Crisman Mark V. , Ward Daniel L. , Robertson John L. , Finco Delmar R. , Braselton W. Emmett
Published: December 2005

Objective—To determine whether pharmacokinetic analysis of data derived from a single IV dose of iohexol could be used to predict creatinine clearance and evaluate simplified methods for predicting serum clearance of iohexol with data derived from 2 or 3 blood samples in clinically normal foals.

Animals—10 healthy foals.

Procedure—Serum disposition of iohexol and exogenous creatinine clearance was determined simultaneously in each foal (5 males and 5 females). A 3-compartment model of iohexol serum disposition was selected via standard methods. Iohexol clearance calculated from the model was compared with creatinine clearance. Separate limited-sample models were created with various combinations of sample times from the terminal slope of the plasma versus time profile for iohexol. Correction factors were determined for the limited-sample models, and iohexol clearance calculated via each method was compared with exogenous creatinine clearance by use of method comparison techniques.

Results—Mean exogenous creatinine clearance was 2.17 mL/min/kg. The disposition of iohexol was best described by a 3-compartment open model. Mean clearance value for iohexol was 2.15 mL/min/kg and was not significantly different from mean creatinine clearance. A method for predicting serum iohexol clearance based on a 2-sample protocol (3- and 4-hour samples) was developed.

Conclusions and Clinical Relevance—Iohexol clearance can be used to predict exogenous creatinine clearance and can be determined from 2 blood samples taken after IV injection of iohexol. Appropriate correction factors for adult horses and horses with abnormal glomerular filtration rate need to be determined. (Am J Vet Res2003;64:1486–1490)
Use of a multiplex polymerase chain reaction assay in the antemortem diagnosis of toxoplasmosis and neosporosis in the central nervous system of cats and dogs
Authors: Schatzberg Scott J. , Haley Nicholas J. , Barr Stephen C. , deLahunta Alexander , Olby Natasha , Munana Karen , Sharp Nicholas J. H.
Published: December 2005

Objective—To develop a multiplex polymerase chain reaction (PCR) assay for the detection ofToxoplasma gondiiandNeospora caninumDNA in canine and feline biological samples.

Sample Population—Biological samples from 7 cats with systemic (n = 4) or CNS (3) toxoplasmosis, 6 dogs with neospora- or toxoplasma-associated encephalitis, and 11 animals with nonprotozoal disease.

Procedure—Primers forT gondii, N caninum, and the canine ferritin gene (dogs) or feline histone 3.3 gene (cats) were combined in a single PCR assay. The DNA was extracted from paraffin-embedded brain tissue, CSF, or skeletal muscle. The PCR products with positive results were cloned, and sequence identity was confirmed.

Results—Of 7 cats and 4 dogs with immunohistochemical or serologic evidence of toxoplasmosis, PCR results were positive for all cats and 3 dogs forT gondii, and positive forT gondiiandN caninumfor 1 dog. Another dog had negative PCR results for both parasites. Of 2 dogs with immunohistochemical or serologic evidence of neosporosis, PCR results were positive for 1 forN caninumand positive for the other forT gondii. All negative-control samples yielded negative results forT gondiiandN caninumon the PCR assay.

Conclusions and Clinical Relevance—Standard tests for toxoplasmosis or neosporosis associated with the CNS rely on serologic, histologic, or immunohistochemical analysis and can be difficult to interpret. The multiplex PCR assay with built-in control reactions could be a complementary clinical tool for the antemortem diagnosis of toxoplasmosis or neosporosis associated with the CNS. (Am J Vet Res2003;64:1507–1513)
Evaluation of serum concentrations of biochemical markers of bone metabolism and insulin-like growth factor I associated with treadmill exercise in young horses
Authors: Jackson Brendan F. , Goodship Allen E. , Eastell Richard , Price Joanna S.
Published: December 2005

Objective—To evaluate changes in serum concentrations of biochemical markers of bone metabolism and insulin-like growth factor I (IGF-I) associated with treadmill exercise in young horses.

Animals—12 two-year-old Thoroughbred mares.

Procedure—During a 20-week study period, 6 horses were exercised on a treadmill 3 times a week (exercise group) and 6 horses received walking exercise 6 days a week (controls). Serum concentrations or activity of biochemical markers and IGF-I were assessed biweekly. Bone mineral density and content of the first phalanx were measured by dual-energy X-ray absorbiometry (DEXA) on completion of the study.

Results—Compared with values in controls, bone mineral density and content were higher and serum concentrations of osteocalcin (a marker of bone formation) and the carboxy-terminal telopeptide of type I collagen (a marker of bone resorption; ICTP) were lower in exercised horses. Serum concentration and activity of the bone formation markers carboxy-terminal propeptide of type I collagen and bone-specific alkaline phosphatase (BAP) were not different between the 2 groups. Serum IGF-I concentration was lower in the exercise group, compared with control values; there was a significant correlation between change in IGF-I values and changes in osteocalcin, ICTP, and BAP values at the end of the study.

Conclusions and Clinical Relevance—Treadmill exercise over 20 weeks induced adaptive changes in bones of 2-year-old Thoroughbreds; training appears to increase bone mineral density, thereby enhancing mechanical strength of bone, but decreases bone turnover. Results indicated an association between changes in serum IGF-I concentration and bone cell activity in horses. (Am J Vet Res2003;64:1549–1556)
Effects of hydrochloric, acetic, butyric, and propionic 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 the pathogenesis of gastric ulcers by comparing injury to the nonglandular gastric mucosa of horses caused by hydrochloric acid (HCl) or volatile fatty acids (VFAs).

Sample Population—Gastric tissues from 30 horses.

Procedure—Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance calculated for tissues after addition of HCl and VFAs to normal Ringer's solution (NRS). Tissues were examined histologically.

Results—Mucosa exposed to HCl in NRS (pH, 1.5) had a significant decrease in Isc, compared with Isc for mucosa exposed to NRS at pH 4.0 or 7.0. Also, exposure to 60mM acetic, propionic, and butyric acids (pH, 4.0 or 1.5) caused an immediate significant decrease in Isc. Recovery of sodium transport was detected only in samples exposed to acetic acid at pH 4.0. Recovery of sodium transport was not seen in other mucosal samples exposed to VFAs at pH ≤ 4.0.

Conclusions and Clinical Relevance—Acetic, butyric, and propionic acids and, to a lesser extent, HCl caused decreases in mucosal barrier function of the nonglandular portion of the equine stomach. Because of their lipid solubility at pH ≤ 4.0, undissociated VFAs penetrate cells in the nonglandular gastric mucosa, which causes acidification of cellular contents, inhibition of sodium transport, and cellular swelling. Results indicate that HCl alone or in combination with VFAs at gastric pH ≤ 4.0 may be important in the pathogenesis of gastric ulcers in the nonglandular portion of the stomach of horses. (Am J Vet Res2003;64:404–412)
Evaluation of relationships between pretreatment patient variables and duration of isolation for radioiodine-treated hyperthyroid cats
Authors: Weichselbaum Ralph C. , Feeney Daniel A. , Jessen Carl R.
Published: December 2005

Objective—To determine relationships between commonly measured pretreatment variables and duration of isolation for unrestricted dismissal after oral administration of iodine 131 (131I) for treatment of hyperthyroidism in cats.

Animals—149 hyperthyroid cats treated with131I.

Procedure—A dose of131I (2.9 to 6.04 mCi [1.07 to 2.23 × 108Bq]) was administered orally to all cats after hyperthyroidism was confirmed by evaluation of serum total thyroxine (T4) concentrations. Forward stepwise regression analysis was used to determine whether pretreatment total T4concentration, serum creatinine concentration, body weight, age,131I dose, or concurrent administration of cardiac medication (specifically excluding thyroid suppression drugs) could be used as pretreatment predictors of duration of isolation in a clinical setting. Gamma radiation emission rate at dismissal was < 2.0 mR/h at skin surface over the thyroid region.

Results—Mean ± SD duration of isolation was 16.67 ± 4.42 days (95% confidence interval, 9.2 to 24.1 days). The regression equation for duration of isolation calculated on the basis of dose of131I (duration of isolation [days] = 3.2 + [2.66 × mCi –131I dose]) yielded a regression line with a 95% confidence interval of ± 3.3 days; only 15% of the variation was explained.

Conclusions and Clinical Relevance—A pretreatment estimate for duration of isolation could be determined only from an equation based on the orally administered dose of131I. These findings suggest that administration of the lowest efficacious dose possible is the dominant factor in reduction of duration of isolation for cats treated with131I. (Am J Vet Res2003;64:425–427)
Characterization of the diversity of Haemophilus parasuis field isolates by use of serotyping and genotyping
Authors: Oliveira Simone , Blackall P. J. , Pijoan Carlos
Published: December 2005

Objective—To characterize the genetic diversity ofHaemophilus parasuisfield isolates with regard to serovar, herd of origin, and site of isolation.

Sample population—Isolates ofH parasuisobtained from pigs in 15 North American herds and multi-farm systems.

Procedure—98H parasuisisolates were genotyped with the enterobacterial repetitive intergeneic consensus based-polymerase chain reaction (ERIC-PCR) technique and serotyped via agar gel precipitation test. Genomic fingerprints were analyzed and dendrograms were constructed to identify strains from the same serovar group, herd of origin, or isolation site and to evaluate the genetic variability within these categories.

Results—Serovar 4 (39%) and nontypeable (NT) isolates (27%) were most prevalent. Thirty-four distinct strains were identified among the 98 isolates, using a 90% similarity cutoff. Strains from serovar 4 and NT isolates had high genetic diversity (12 and 18 strains, respectively). One to 3 major clusters of prevalent strains could be identified in most of the evaluated herds.Haemophilus parasuisstrains isolated from the upper respiratory tract were either serovar 3 or NT isolates. Potentially virulent strains (isolated from systemic sites) were either serovars 1, 2, 4, 5, 12, 13, or 14, or NT isolates.

Conclusions and Clinical Relevance—AlthoughH parasuishad high genetic diversity overall, only a few strains caused disease in these herds. The ERIC-PCR technique was more discriminative than serotyping, and a broad genetic variety was observed within particular serovar groups. (Am J Vet Res2003; 64:435–442)