bluuebunny/crossref_metadata_2025 huggingface dataset:
A permeability barrier in the dorsal wall of the equine hoof capsule
Authors: KEMPSON SUSAN A. , CAMPBELL ELAINE H.
Published: June 2010

The permeability barrier in the dorsal wall of the equine hoof capsule was studied by means of horseradish peroxidase (HRP) in 0.9 N saline solution as a water soluble tracer. Sections were treated with 3′3′‐diaminobenzidine tetrachloride (DAB) and before dissection the quality of the horn of feet from 10 horses was assessed and given a subjective grade as either good or poor. Blocks of tissue from each horse were left in either an oven at 60°C or in water for 2 weeks before treatment in HRP, sectioning and DAB solution. Regions observed were i) outer surface, ii) outermost layers of the horn, iii) cut edge of the outer layer, iv) inner layer of horn, v) cut edge of the inner layer and vi) laminae. Horn deemed to be normal horn and of good ‘quality’ showed very slight penetration of HRP 3–5 cell layers deep in the outer layer. The cut edge of the outer layer of the wall of the ‘normal’ horn also showed minimal penetration of HRP through the intercellular spaces. The cut edge of the inner layers of the wall of normal, good quality horn showed penetration of the tracer up to 20 cell layers deep, with HRP in both the intercellular spaces and within the cells. In contrast, sections of horn from horses with brittle feet showed deep cracks in the outer surface into which the HRP had penetrated.

Good quality horn showed no change in the position of the permeability barrier after soaking in water for 14 days, but the brittle horn showed an increase in permeability to HRP. In brittle horn, reaction product was seen deep within the section in the intercellular spaces of the intertubular horn only. Placing horn in an oven had no effect on the permeability barrier. The permeability barrier of the dorsal wall of the equine hoof capsule differs with the layer of the wall. Horn considered to be of poor quality had a weaker permeability barrier than horn of good quality.
Onychomycosis in white line disease in horses: pathology, mycology and clinical features
Authors: KUWANO A. , YOSHIHARA T. , TAKATORI K. , KOSUGE J.
Published: June 2010

This paper describes onychomycosis in horses and reports the pathological findings, associated fungi and incidence of concurrent white line disease. In addition to these observations, relevance between post mortem and clinical findings of onychomycosis are discussed in 3 necropsied horses. Samples were collected from 100 hooves from a total of 51 Thoroughbreds suffering from white line disease. Of these, 15 hooves from 13 horses were also complicated with severe hoof wall fissure formation. Preparations from the same samples were used both for histopathology and for culture to identify the associated fungi. Onychomycosis was diagnosed when it could be confirmed histologically. Fungal identification was based on morphological characteristics in culture and the associated fungi were determined by comparison with culture morphology. As a result, 10 samples collected from horses were diagnosed as suffering from onychomycosis. Seven of these showed complicating severe inner hoof wall fissures and the soil fungus Scedosporium apiospermum or the teleomorph of this fungus, i.e., Pseudallescheria boydii, was isolated. The fungus was found to be ubiquitous in the fissure cavities, the terminal horn of the white line and the terminal horn‐like laminae of the metaplastic white line‐like tissue. It can be concluded that onychomycosis frequently causes white line disease and/or makes it worse. Associated with deterioration of the submural condition, the main associated fungus for onychomycosis in this series, was Genus Scedosporium and the most susceptible region was the terminal horn of the hypertrophied white line and/or the terminal horn‐like laminae of the metaplastic white line‐like tissue.
Effect of supplementary dietary biotin on hoof growth and hoof growth rate in ponies: a controlled trial
Authors: REILLY J. D. , COTTRELL D. F. , MARTIN R. J. , CUDDEFORD D. J.
Published: June 2010

The effect of dietary biotin supplementation, at a dose rate of 0.12 mg/kg bwt, on growth and growth rate of the hooves of 8 match‐paired ponies was investigated in a controlled feeding trial. Treatment animals had a mean hoof growth at the midline dead centre of the hoof capsule of 35.34 mm after 5 months of biotin supplementation compared to control animals 30.69 nun (P<0.05). Comparison of regression analysis also showed that biotin supplementation produced a significantly higher (P<0.02) growth rate of hoof horn in this trial. Treatment animals had a 15% higher growth rate of hoof horn and 15% more hoof growth at the midline dead centre, after 5 months of biotin supplementation compared to control ponies. No differences were found between feet for growth of horn, but the older animals in the trial had significantly lower hoof growth (P<0.05) than the remaining ponies.
Equine laminitis: its development coincides with increased sublamellar blood flow
Authors: POLLITT C. C. , DAVIES C. T.
Published: June 2010

The effect of alimentary carbohydrate overload on hoof temperature was investigated to determine the state of the sublamellar vasculature preceding the onset of equine laminitis. Hoof, core and ambient temperatures and heart rate were logged continuously in 21 mature Standardbred horses kept in an environmental chamber set at 10°C. Recording hoof temperature was a successful, noninvasive, method to measure indirectly, shifts in digital blood flow against a background of cold induced, physiological, vasoconstriction. High hoof temperatures were assumed to indicate digital vasodilation and low hoof temperatures digital vasoconstriction. Seven horses were either untreated or sham treated controls. A slurry of ground wheat flour (17.5 g/kg) was administered via nasogastric tube to 13 horses all of which were humanely killed 48 h later. Histological sections of the lamellar tissues were examined for evidence of laminitis. Analysis of mean hoof temperature graphs showed that horses judged laminitis positive had experienced a period of prolonged digital vasodilation 16–40 h after carbohydrate overload. Laminitis negative horses experienced no such period of vasodilation and never had hoof temperatures significantly (except once, at 28 h) above that of controls. The only parameter which significantly differentiated the laminitis positive from laminitis negative horses, between 12 and 32 h after carbohydrate overload, was foot temperature, which was significantly higher in laminitis positive horses (P<0.05). Therefore, a period of sublamellar vasodilation, 12 to 40 h after alimentary carbohydrate overload precedes the onset of laminitis. If the digital circulation sustains vasoconstriction during this period then laminitis does not occur. We propose that the period of increased digital blood flow in laminitis positive horses, concomitant with the severe metabolic crisis brought on by the alimentary carbohydrate overload, may expose the lamellar tissues to a concentration of blood borne factors sufficient to trigger lamellar separation.
Characterisation of headshaking syndrome −31 cases
Authors: MADIGAN J. E. , BELL STEPHANIE A.
Published: June 2010

Headshaking is a maturity onset condition with the most commonly reported clinical signs being 'flipping' of the nose, nose rubbing, snorting or sneezing, and acting like a bee is flying up the nostril. A questionnaire was completed by owners of 31 horses with headshaking syndrome. The history, time of onset, clinical presentation and treatment of this condition were reported. Headshaking appeared to be light‐stimulated in approximately 60% of the horses. The condition is seasonal and recurring in the majority of horses. Treatment with cyproheptadine produced improvement of symptoms in 76% of cases. The clinical signs are suggested to be compatible with neuropathic pain producing itching, tingling or electric like sensations in the face and muzzle area of affected horses.
Perceptions and attitudes towards horses in European societies
Authors: ENDENBURG N.
Published: June 2010

In spite of the fact that horses were domesticated between 5000 and 3000 B.C., the relations between humans and horses constitutes a relatively unexplored area. This may be due to the fact that horses in middle class western society are seen as companion animals, of primarily social and recreational value. Horses, however, have historically enjoyed an enormously important utilitarian, economic and sporting significance and in many countries horse meat is also eaten.

Nowadays, we can classify the different ways in which horses are used into four different fields:

• recreational and/or social purposes

• breeding

• sport and competition

• meat production

In each category one can distinguish 4 main areas of concern:

• the behaviour and wellbeing of the horse

• feeding

• maintenance

• veterinary care

All 4 fields make their own particular demands on these aspects of the care of horses. In addition, people have also approached these different fields of equine exploitation through the centuries with different attitudes. The goal of this article is to review the attitudes of people towards horses. The main conclusion of this article is that the diversity of uses for equines and corresponding organisations makes it difficult to get a clear overview and thereby inhibits scientific research into human‐horse interactions.
Comparative pathophysiology of nonglandular ulcer disease: a review of experimental studies
Authors: ARGENZIO R. A.
Published: June 2010

Ulceration of the nonglandular, stratified squamous mucosa of the equine and porcine stomach is a common event in both species, although in pigs the fatality rate is significant and it is an economically important disease. Because the barrier function of this mucosa in horses and pigs appears similar, it is probable that similar pathophysiological mechanisms may be responsible for the initiating lesions and reparative events. Recent studies of ulcer pathogenesis in the pig have shown that feed preparation or prolonged fasting can result in disruption of the normal stratification of gastric contents, thereby allowing high concentrations of HCl, pepsin and refluxed bile to mix in the proximal stomach. Conditions simulating those foundin vivohave been shown to damage this mucosain vitroand indicate that luminal products, such as short chain fatty acids and bile salts, which act in synergy with HCl, probably are necessary to induce significant damage to this mucosa. Studies of the equine stomach have shown a similar proximal to distal pH gradient in the fed stomach, a significant duodenal‐gastric reflux, and induction of squamous ulcers with fasting, thereby illustrating that similar conditions may be responsible for damage to the equine nonglandular mucosa.
Induction and maintenance of gastric ulceration in horses in simulated race training
Authors: VATISTAS N. J. , SIFFERMAN R. L. , HOLSTE J. , COX J. L. , PINALTO G. , SCHULTZ K. T.
Published: June 2010

Gastric ulceration is a prevalent condition of racehorses. A number of models of gastric ulceration have been described, but none mimic the conditions of a horse in training. The objectives of this study were to determine whether gastric ulcers could be induced and maintained in a group of horses in simulated race training. In addition, serum Cortisol was measured on a weekly basis to investigate the possibility that stress may be important in the pathogenesis of gastric ulceration. Thirty horses used in the trial were fed Bermuda grass hay and 6 kg of a concentrate diet, and exercised 6 days/week at speed over a distance of 1.6–2.4 km. Serum was collected and gastroendoscopic examinations performed on a weekly basis for the duration of the trial. All horses developed moderate to severe ulceration, and ulcers were maintained for the 56 day period of the trial. Only one horse had signs of abdominal discomfort, which resolved with minimal symptomatic treatment and without the use of antiulcer medications. Serum Cortisol remained within reference ranges for the duration of the trial. Although there was some variation between the weekly examinations, serum Cortisol concentrations were decreased from values obtained at the start of the trial. In this study ulcers developed without the administration of nonsteroidal anti‐inflammatory agents or withholding of feed. This model provides a method to study the condition, and to investigate the effects of medications on the healing of ulcers in racehorses.
Investigation of an outbreak of tapeworm‐associated colic in a training yard
Authors: PROUDMAN C. J. , HOLDSTOCK N. B.
Published: June 2010

A novel serological assay which measures IgG(T) specific for a 12/13 kDa protein of the equine tapewormAnoplocephala perfoliatawas used as part of a colic outbreak investigation. A training/rehabilitation yard for Thoroughbreds and Arabs was found to have an increasing incidence of colic over a 5 year period, culminating in a peak incidence of 1.15 episodes/horse year at risk. Four animals suffered from ileal impaction colic which necessitated surgical management. A case‐control study design suggested a strong association between tapeworm infection and colic, with evidence of a dose‐response relationship. Intervention, in the form of anticestode anthelminthics, coincided with a decrease in the incidence of colic and a fall in anti‐12/13 kDa IgG(T) antibody levels of 8 horses monitored post‐treatment. This study demonstrates that anthelminthic regimens, using exclusively ivermectin, may lead to an increase in tapeworm infection intensity which may in turn lead to an increased incidence of colic. Furthermore, it provides support to the hypothesis that the risk of ileal impaction colic and spasmodic colic increases with tapeworm infection intensity. The practical application of the anti‐12/13 kDa IgG(T) ELISA is demonstrated by this study.
Design and clinical use of a modified colon tray for large colon evacuation in the horse
Authors: MARIËN T. , ADRIAENSSEN A. , SEGERS L.
Published: June 2010

A modified colon tray to perform large colon evacuations in horses was designed. A funnel‐shaped accessory was constructed to create a mechanical separation between the sterile and nonsterile part of the tray. Sterile hooks were used to make a temporary and stabile colostomy. Thirty horses with surgical correction of nonstrangulating large colon obstruction underwent a large colon evacuation with this modified tray. The surgical procedure was uncomplicated and resulted in a positive outcome in 29 horses. This less labour‐intensive way to evacuate the large colon results in minor contamination and makes extraluminal lavage becomes superfluous. This modified tray is a very efficacious and practical instrument for emptying the large colon in horses.
Equine lymphocytic‐plasmacytic enterocolitis: A retrospective study of 14 cases
Authors: KEMPER D. L. , PERKINS G. A. , SCHUMACHER J. , EDWARDS J. F. , VALENTINEN B. A. , DIVERS T. J. , COHEN N. D.
Published: June 2010

Lymphocytic‐plasmacytic enteritis (LPE) is a morphological diagnosis given to a type of infiltrative intestinal disease classified within the complex of idiopathic inflammatory bowel disease (IBD). The purpose of this retrospective study was to describe the details of breed, age and sex, clinical and clinicopathological findings and outcome of horses diagnosed with LPE. Data were reported from 14 horses that had a histopathological diagnosis of LPE; the median age was 12 years, and there was no breed or sex predilection. Common clinical signs were weight loss (100%), diarrhoea (50%) and lethargy (50%). Hypoproteinaemia and hypoalbuminaemia were present in 6/13 (46%) and 9/12 (75%) horses, respectively. Results of the oral glucose tolerance tests or D‐xylose absorption tests were abnormal in 9/12 (75%) horses and rectal mucosal biopsies were abnormal in 3/7 (43%) horses. Corticosteroid treatment was used unsuccessfully in 4 horses. All horses were subjected to euthanasia and LPE was diagnosed at necropsy. Diffuse thickening of the small intestine was apparent grossly in 10/13 (77%) horses examined. LPE is an uncommon equine intestinal disease that is difficult to diagnoseantemortemand has a poor prognosis.
Relationships between third metacarpal bone parameters and surface strains
Authors: DAVIES H. M. S.
Published: June 2010

The relationships were explored between measurements of bone quality, size (quantity) and shape, and strain data collected during treadmill exercise at 4 and 12 m/s from the third metacarpal bones of 6 yearling and 6 mature Thoroughbred racehorses. Peak strains in yearling and mature Thoroughbred horses during exercise were related to the size and shape of the third metacarpal bone. The peak strains were significantly lower in horses with a greater cross‐sectional area of bone and with a greater proportion of the bone in the dorsal cortex. There was no consistent relationship between peak strains and bone quality assessed by ultrasound speed, single photon absorptiometry and direct measurement of porosity and specific gravity. It was concluded that measurement of the dorsal cortical proportions of the third metacarpal bone may provide a way of estimating the level of strains caused by fast exercise in this part of the bone, and hence the modelling response to be expected.
Sensitivity of forelimb swing phase inverse dynamics to inertial parameter errors
Authors: LANOVAZ J. L. , CLAYTON H. M.
Published: June 2010

Estimations of segmental inertial parameters are required for true inverse dynamics calculations during the swing phase of locomotion. This study attempts to quantify the effect of inertial parameter errors on inverse dynamic solutions. Swing phase forelimb net joint moments and powers at the trot (mean ± s.d 3.03 ± 0.16 m/s) were calculated with sagittal plane kinematic data from 5 Dutch Warmbloods using inertial parameters based on published regression equations for the breed. Significant peaks in the net moment and power curves for each forelimb joint were identified and measured. Net joint moments and powers were then recalculated after varying the segment mass, location of the segment centre of mass and the mass moment of inertia separately for each of the limb segments. Peak values for the net joint moments and joint powers were determined after each variation, and the percent change in peak value per percent change in inertial parameter was calculated. Segment mass was the most influential parameter, followed by location of the centre of mass. Changes in the mass moment of inertia showed little effect on peak values. The most influential single inertial parameter was the mass of the hoof segment with a mean ± s.d effect 0.74 ± 0.22 and 0.69 ± 0.18 percent peak change per percent parameter change on net joint moments and powers, respectively, across all joints. The results demonstrate the need for an accurate approximation of segment masses during the swing phase, especially the hoof, and the need to account for any additional masses in the model, such as shoes.
Finite element analysis (FEA) as a model to predict effects of farriery on the equine hoof
Authors: HINTERHOFER C. , STANEK C. , HAIDER H.
Published: June 2010

A finite element (FE) hoof capsule was built as a small, symmetrical forelimb hoof on IDEAS* as a model for calculation and visualisation of stress and displacement of the equine hoof capsule. The model's loading was performed according to the suspension of the coffin bone within the hoof wall (pulling force) and over the sole and frog (compressing force) with a total of 3000 N. Restraints of the model's ground nodes and surface wall nodes were defined for simulation of 4 shoeing situations: a regular horseshoe, a horseshoe with a toe clip, a horseshoe with regular side clips and a horseshoe with a toe clip and more caudally‐placed side clips, all fixed to the hoof capsule with 3 nails on each side and each calculated in a tense and a loose nailed condition. Von Mises stresses were taken ranging from 1.22 N/mm2in the weighthearing border of the side clip shoe fixed loosely to the capsule up to 16.67 N/mm2in the hoof horn material surrounding the third nail. Further high stress zones were calculated in the proximal dorsal wall, the distal heel and the lateral hoof wall. Displacement values were taken showing movements of hoof wall, sole and frog according to the shoeing conditions. Maximal displacement was calculated in the hoof capsule shod with a regular horseshoe without a clip. Minimal displacement was found in the capsule with a toe clip and 2 side clips placed behind the 3rd nail. All models showed higher displacements when calculated with a loose nail fixation.

Validation of the detailed features of the models is not yet possible. Finite element analysis (FEA) can be used practically to predict influences of various farrier techniques on the equine hoof in order to avoid possible harm to horses' feet in field studies.
Components of variation of surface hoof strain with time
Authors: THOMASON J. J. , BIGNELL W. W. , SEARS° W.
Published: June 2010

The relative contribution of a number of random and fixed variables to variation in surface strain magnitudes on the hoof capsule was assessed for healthy feet under normal conditions. Principal strains were recorded in vivo from 5 rosette gauges glued around the circumference of the right forefeet of 4 horses on 4 occasions over a 9 month period. Recordings were made at every other trimming and reshoeing. During each session, gauges were positioned with a template for repeatability. Strains were recorded at the trot and canter (at consistent speeds), for straight motion and turns, and before and after the hoof was trimmed and reset. Up to 30 strides were recorded for each combination of these variables. ANOVAs were performed on midstance strains of 7008 strides to determine the relative contributions to strain variation of individual horse, test day, gait and direction combined as one factor, gauge position on the hoof, trimming, interstride variability and the interactions among these factors.

The ANOVA model explained 87% of the variation, of which approximately 84% was due to fixed effects and 16% to random effects. Circumferential position of the gauges and several of the interactions including this term were by far the greatest contributors to strain variation.

Differences among gauge positions, individuals and gait+direction are consistent with previous work. This study has added the relative effects, which are small but significant, of trimming on a regular basis and of time. The change in strain magnitudes with trimming was different for each horse, which leads to the possibility that over‐ and underuse may have to be quantified on an individual basis.
Modification of a force plate system for equine gait analysis on hard road surfaces: a technical note
Authors: WILSON A. M. , PARDOE C. H.
Published: June 2010

Studies on horseshoe materials have been limited to the analysis of kinematic data to determine slip times and distances, since equine force plate analysis is traditionally undertaken on a rubber‐surfaced force plate. The purpose of this study was to modify a force plate for measuring ground reaction forces on a road surface and report preliminary data from the system.

A steel‐reinforced concrete top plate of 18 mm thickness and mass 23 kg, and a 12 mm thick top plate of 6 mm bituminous macadam wear coat (road surface) contained in a tray constructed of 2 mm thick steel, mass 21 kg, were constructed. The top plates were bolted to a forceplate and resonance frequency of the force plate top plate combinations were 278 Hz (concrete) and 218 Hz (roadway), respectively.

Simultaneous kinetic and kinematic data were collected while a horse, shod in steel horseshoes, was trotted over the concrete‐topped force plate until 8 foot placements were recorded. The foot slipped for mean ± s.d. 35± 7 mm in 29 ±8 ms after impact and both Fy and Fz increased during foot slip. The ratio of Fy/Fz during slip was relatively constant at 0.56 ± 0.05.

The top plates have proved resilient in use and have withstood a variety of horseshoe designs and tungstencapped stud nails with minimal damage. They enable measurement of ground reaction forces on hard surfaces and the calculation of the energy dissipated via foot slippage by integration of the craniocaudal force‐foot position data after impact.
Comparison between radiological and magnetic resonance imaging lesions in the distal border of the navicular bone with particular reference to distal border fragments and osseous cyst‐like lesions
Authors: BIGGI M. , DYSON S.
Published: June 2010

Reasons for performing study: There are no data concerning the accuracy of conventional and computed or digital radiography for evaluation of the equine foot.

Objectives: To compare conventional film‐screen and computed radiography with magnetic resonance imaging (MRI) for detection of distal border fragments of the navicular bone; and to establish which type of fragment was more likely to be detected radiologically.

Methods: Horses were included if forelimb lameness was localised to the foot and both radiography and high‐field MR images had been acquired. Horses were divided into 2 groups based on acquisition of conventional (Group A) or computed (Group B) radiographs. The presence of distal border fragments was recorded. From MR images, distal border fragments were graded based on their size and changes in signal intensity in the adjacent navicular bone. Sensitivity and specificity of conventional and computed radiography for detection of fragments were calculated using MRI as the gold standard. A Chi‐squared test was used to test for associations between specific radiological and MRI findings in the distal border of the navicular bone.

Results: In Group A 46 and 18 fragments were identified on MR and radiographic images, respectively; in Group B 45 and 17 fragments were seen. There was no significant difference between computed and conventional radiography. Grades 4 and 5 fragments or large‐sized fragments were identified most frequently; low‐grade fragments were unlikely to be observed. There was a significant correlation between radiological and MRI abnormalities of the distal border of the navicular bone.

Conclusions: Conventional and computed radiography had similar, rather low sensitivity for identification of distal border fragments of the navicular bone, but specificity was high. Large‐sized and high‐grade fragments were most likely to be identified radiologically.

Potential relevance: Fragments observed radiologically are likely to be associated with other pathological abnormalities of the distal border of the navicular bone.
Effects of Mass Transfer and Free-Convection Currents on the Flow Near a Moving Vertical Plate With Ramped Wall Temperature
Authors: Narahari M. , Dutta Binay K.
Published: June 2010

A theoretical analysis to the problem of free convection flow induced by an infinite moving vertical plate subject to a ramped surface temperature with simultaneous mass transfer to or from the surface is presented. The plate temperature increases linearly over a specified period of time until it reaches a constant value. Diffusional mass transfer occurs at the surface contributing to the density gradient in the boundary layer. An exact analytical solution to the governing equations for flow, temperature and concentration with coupled boundary conditions in the dimensionless form have been developed using the Laplace transform technique. Heat and mass transfer at the plate are assumed to be purely diffusive in nature. The cases of impulsive start and uniformly accelerating start of the plate are considered and solutions for the flow, temperature and concentration fields are derived. The effects of different system parameters have been studied in terms of relevant dimensionless groups such as Grashof number (Gr), Prandtl number (Pr), Schmidt number (Sc), time (t) and the mass to thermal buoyancy ratio (N). The possible cases of the last parameter, namely N = 0 (the buoyancy force is due to thermal diffusion only), N > 0 (the mass buoyancy force acts in the same direction of thermal buoyancy force) and N < 0 (the mass buoyancy force acts in the opposite direction of thermal buoyancy force) are investigated and their effects on the velocity field and skin-friction are explicitly determined. The ramped temperature boundary condition predictably has an enhancing effect on the skin friction. The mass flux to the plate influences the velocity and hence the skin friction. A critical analysis of the coupled heat and mass transfer phenomena is provided. The free convection near a ramped temperature plate has also been compared with the flow near a plate with constant temperature as a limiting case.
Reactor Scale Model of Multiwalled Carbon Nanotube Growth in a Tube Flow Chemical Vapor Deposition Reactor
Authors: Lombardo Jeffrey J. , Chiu Wilson K. S.
Published: June 2010

Even though a large number of applications for multiwalled carbon nanotubes have been proposed, there is relatively limited knowledge about the optimal conditions in which to create multiwalled carbon nanotubes (MWNTs). Computational models have been shown to be a promising tool to determine the best carbon nanotube growth conditions. In this paper the growth of MWNTs in a tube flow CVD reactor was studied through the use of the commercial software package COMSOL, where details steps have been described to reformulate an existing single walled carbon nanotube (SWNT) growth model to accommodate MWNTs followed by validation and growth rate prediction. Higher growth rates were predicted for MWNTs than SWNTs which is a result of the increase in pathways for carbon to form carbon nanotubes based on the additional walls. Results indicate that selecting the correct number of walls can be important to the results of the model.
Air Jet Impingement Heat Transfer at Low Nozzle-to-Plate Spacings Under a Fixed Pumping Power Condition
Authors: Choo Kyo Sung , Kim Sung Jin
Published: June 2010

Heat transfer characteristics of an impinging air jet are experimentally investigated under a fixed pumping power condition. The effects of dimensionless pumping power on the Nusselt number are considered. The focus is on cases where the nozzle-to-plate spacing is equal to or less than one nozzle diameter. The results show that the Nusselt number is independent of the nozzle-to-plate spacing under fixed pumping power conditions, while the Nusselt number increases with decreasing the nozzle-to-plate spacing under fixed flow rate conditions. Based on the experimental results, new correlations for the stagnation and average Nusselt numbers of the impinging jet are developed as a function of the pumping power alone.
A Numerical Investigation of Automobile Environment Through Cooling Period and Condensation
Authors: Kader Md. Faisal , Goo Kang Hyu , Jun Yong-Du , Lee Kum-Bae
Published: June 2010

Understanding the fluid flow and heat transfer characteristics within a vehicle compartment is very important for controlling the effect of major design parameters. Also, adequate visibility through the vehicle windshield over the entire driving period is of paramount practical significance. The numerical solution was done by an operation friendly, fast and accurate CFD code — SC/Tetra with a full scale model of a SM3 car and turbulence was modeled by the standard k-ε equation. Numerical analysis of the three-dimensional model predicts a detailed description of fluid flow and temperature distribution in the passenger compartment and on the inside windshield screen. During the cooling period, the lowest temperature is observed in the lower part of the windshield and in the vicinity of the defroster griller. It was found that the temperature dropped down to a comfortable range almost linearly at the initial stage. The initial period to achieve this comfortable range is dependent on the inlet velocity. Experimental investigations are performed to determine the localized thermal comfort and further validation of the numerical results.
Real-Time Reliable Simulation of Heat Transfer Phenomena
Authors: Rozza G. , Huynh D. B. P. , Nguyen N. C. , Patera A. T.
Published: June 2010

In this paper we discuss the application of the certified reduced basis method and the associated software package rbMIT© to “worked problems” in steady and unsteady conduction. Each worked problem is characterized by an input parameter vector — material properties, boundary conditions and sources, and geometry — and desired outputs — selected fluxes and temperatures. The methodology and associated rbMIT© software, as well as the educational worked problem framework, consists of two distinct stages: an Offline (or “Instructor”) stage in which a new heat transfer worked problem is first created; and an Online (or “Lecturer”/“Student”) stage in which the worked problem is subsequently invoked in (say) various in-class, project, or homework settings. In the very inexpensive Online stage, given an input parameter value, the software returns both (i) an accurate reduced basis output prediction, and (ii) a rigorous bound for the error in the reduced basis prediction relative to an underlying expensive high-fidelity finite element discretization; as required in the educational context, the response is both rapid and reliable. We present illustrative results for two worked problems: a steady thermal fin, and unsteady thermal analysis of a delamination crack.
A Way to Visualise Heat Transfer in 3D Unsteady Flows
Authors: Speetjens M. F. M.
Published: June 2010

Heat transfer in fluid flows traditionally is examined in terms of temperature field and heat-transfer coefficients. However, heat transfer may alternatively be considered as the transport of thermal energy by the total convective-conductive heat flux in a way analogous to the transport of fluid by the flow field. The paths followed by the total heat flux are the thermal counterpart to fluid trajectories and facilitate heat-transfer visualisation in a similar manner as flow visualisation. This has great potential for applications in which insight into the heat fluxes throughout the entire configuration is essential (e.g. cooling systems, heat exchangers). To date this concept has been restricted to 2D steady flows. The present study proposes its generalisation to 3D unsteady flows by representing heat transfer as the 3D unsteady motion of a virtual fluid subject to continuity. The heat-transfer visualisation is provided with a physical framework and demonstrated by way of representative examples. Furthermore, a fundamental analogy between fluid motion and heat transfer is addressed that may pave the way to future heat-transfer studies by well-established geometrical methods from laminar-mixing studies.
Thermal Conduction Mechanism in Nanofluids, Solid Composites and Liquid Mixtures
Authors: Eapen Jacob
Published: June 2010

Analysis of Maxwell’s mean-field (or effective-medium) theory reveals two limiting bounds — an upper and a lower bound — for thermal conductivity in binary composite systems. The lower and the upper bounds correspond to continuous conduction paths through the base medium and the dispersed medium, respectively (assuming that the dispersed medium has a higher thermal conductivity). Extensive comparisons to experimental data show that most of the reported thermal conductivity data on nanofluids, solid composites and liquid mixtures fall between the limiting Maxwell bounds. For a nanofluid, this indicates that the effective thermal conductivity is largely dependent on the geometrical configuration and the connectivity of the dispersed nanoparticle phase. The lower bound corresponds to a colloidal configuration of well-dispersed nanoparticles with the continuous conduction path provided by the base medium while the upper bound represents a linear, fractal-like nanoparticle arrangement with the continuous conduction path provided by the nanoparticles.
Flow Structure and Heat Transfer Enhancement in Laminar Flow With Protrusion-Dimple Combinations in a Shallow Rectangular Channel
Authors: Alshroof O. , Reizes J. , Timchenko V. , Leonardi E.
Published: June 2010

The effect of introducing combinations of spherical dimples and protrusions in a shallow rectangular channel on the flow and heat transfer in the laminar regime has been studied numerically. Four different cases were investigated. These consisted of: an isolated dimple, an isolated protrusion both placed on the centerline of one of the wide face of the channel, a combination of a dimple located on the centerline of the wide face of the channel and a protrusion located downstream but shifted to the side, and finally, a combination in which the protrusion and the dimple are reversed. The resultant, very complex flow structure and thermal fields in the channel are presented. The introduction of a single dimple results in a small enhancement of heat transfer and a very small reduction in pressure drop relative to those obtained in a smooth channel. However, a significant enhancement in heat transfer obtained from a single protrusion is associated with marginal increase in pressure drop. The addition of a protrusion downstream of the dimple leads to an increase of 30% in heat transfer augmentation above that which pertains for the isolated protrusion without any increase in the pressure drop. With the reversal of the positions of the protrusion and the dimple no effect on either the pressure drop or the heat transfer has been observed.
Experimental Investigation on the Condensation Heat Transfer and Pressure Drop Characteristics of R134A at High Mass Flux Conditions During Annular Flow Regime Inside a Vertical Smooth Tube
Authors: Dalkilic Ahmet Selim , Laohalertdecha Suriyan , Wongwises Somchai
Published: June 2010

This paper presents an experimental investigation on the co-current downward condensation of R134a inside a tube-in-tube heat exchanger. The test section is a 0.5 m long double tube with refrigerant flowing in the inner tube and cooling water flowing in the annulus. The inner tube is constructed from smooth copper tubing of 9.52 mm outer diameter and 8.1 mm inner diameter. The condensing temperatures are between 40 and 50°C, heat fluxes are between 9.78 and 50.69 kW m−2. The temperature difference between the saturation temperature of refrigerant and inlet wall varies between 1.66–8.94°C. Condensation experiments are done at mass fluxes varying between 340 and 456 kg m−2s−1 while the average qualities are between 0.76–0.96. The quality of the refrigerant in the test section is calculated considering the temperature and pressure measured from the test section. The pressure drop across the test section is directly measured by a differential pressure transducer. The average experimental heat transfer coefficient of the refrigerant is calculated by applying an energy balance based on the energy transferred from the test section. Experimental data of annular flow are examined such as the alteration of condensation heat transfer coefficient with the vapor average quality and temperature difference respectively according to different mass fluxes and condensing temperatures. The relation between the heat flux and temperature difference, besides this, the relation between the condensation heat transfer coefficient and condensing pressure are shown comparatively and the effects of mass flux and condensation temperature on the pressure drop are also discussed. The efficiency of the condenser is considered comparing with various experimental data according to tested condensing temperatures and mass fluxes of refrigerant. Some well known correlations and models of heat transfer coefficient were compared to show that annular flow models were independent of tube orientation provided that annular flow regime exists along the tube length and capable of predicting condensation heat transfer coefficient in the test tube.
A Three-Dimensional, Time-Dependent Circulation Model of Utah Lake
Authors: Spall Robert E. , Wilson Brandon , Callister Eric
Published: June 2010

The thermal behavior of Utah Lake, situated in northern Utah, is modeled over a spring-to-fall period using environmental forcing data from the year 2007. Results compare favorably with previously obtained data for temperature distributions around the lake during midsummer 2007. During the spring months, when experimental data is not available, the model predicts strong and rapid variations in the water temperature, which correlate well with significant storms on the lake. A heat balance shows that the largest components of heat fluxes into and out of the lake are due to short wave solar and evaporative cooling, respectively. Both numerical and experimental results also indicate that, due to the shallow nature of the lake and occurrence of significant wind events, thermal stratification is never achieved.
Effect of Array Jet on Cooling Effectiveness on Full-Coverage Film Cooled Surface
Authors: Lee Dong Hyun , Oh Sang Hyun , Jung Eui Yeop , Kim Kyung Min , Cho Hyung Hee
Published: June 2010

In this study, the cooling effectiveness (Φ) was measured on full-coverage film cooled surface with and without array jet impingement cooing using an infra-red thermographic technique. Measurements were conducted with two test plates of different thermal conductivities. One was made of stainless steel (k = 16.3 W/m·K) and the other was made of polycarbonate (k = 0.2 W/m · K). The measured cooling effectiveness comprises the adiabatic film cooling effectiveness on the film cooled surfaces, the heat conduction through the test plates and convective heat transfer of array jet impingement underneath the test plates. The inclination angles of film cooling holes and impingement jet holes were 35° and 90°, respectively. The diameters of both film cooling and impingement jet cooling holes were 5 mm. The streamwise and spanwise hole spacing-to-hole diameter ratios (p/d) are 3 for both the effusion plate (film cooled plate) and the injection plate (impingement nozzle plate. The holes on each plate were arranged in an inline pattern, while the film cooling holes and jet holes were positioned in a staggered manner. The jet Reynolds number based on the hole diameter was 3,000 and the equivalent blowing ratio (M) was 0.3. The gap distance between the jet plate and the film cooling plate was varied from 1 to 5 times of the hole diameter. In addition, the cooling effectiveness without impingement was tested, too. The stainless steel plate shows relatively higher and uniform cooling effectiveness than the polycarbonate plate. The effect of H/d was not significant for both test plates. However, the cooling effectiveness without the impingement jets decreases significantly for the stainless steel plate, while it changed a little for the cooling effectiveness of the polycarbonate plate.
Thermal Performance of a Thin Flat Plate Heat Pipe
Authors: Qu Wei , Li Shijuan , Yang Hongwu
Published: June 2010

A thin flat plate heat pipe (TFPHP) with a new structure of wick is fabricated and tested. The wick is formed by the narrow foils folded, the liquid passage and capillary force is provided by the folded clearance of the foils, the vapor passage is shaped by the periodic holes of the foils. One aluminum TFPHP of 260×60×4 mm3 size is made and the test setup is established. The test results show that the spreader has good performance as, at the horizontal state, the power transferred can reach 18.5W, the corresponding thermal conductivity is 838W/(m·°C). For different tilt angle, we have the performance results. The effects of parameters to the performance are discussed. The spreader is significant for the spreading of point power.
An Investigation of Scale Variation in Multi-Layer Mini- and Micro-Channel Heat Sinks in Single Phase Flow Using a Two Equation Porous Media Model
Authors: Hassell Bryan , Ortega Alfonso
Published: June 2010

Research in liquid cooled mini- and micro-channel heat sinks is growing due to the potentially high heat fluxes that can be dissipated with such devices. Ostensibly, mini- or microchannel heat sinks are derivatives of more generalized porous structures. They are porous, but the pores are continuous and deterministic in structure, with well defined geometries created by etching or cutting channels into solid base material. As such, deterministic small scale heat sinks of this type lend themselves to modeling using the well-developed theories for saturated porous media. Based on the principle that physical problems contain multiple scales with multiple objectives, it is of interest to examine the possibility that allowing scale change away from the heated surface in a multi-layered heat sink would yield greater global benefits. Modeled as a saturated porous medium, scale variation in stacked multi-layer microchannel heat sinks has been explored using an experimentally verified two equation porous model. This paper compares and rates scaling parameters based on the pressure drop across the heat sink along with the unit thermal resistance.
Forced Convection Between a Wire and an Upward Flow Slot Submerged Jet: Preliminary Results
Authors: Baffigi Federica , Bartoli Carlo
Published: June 2010

Heat transfer from a platinum wire 0.2 mm. in dia., heated by Joule effect, to an impinging upward flow submerged slot jet of distilled water is studied in two–phase conditions. A new experimental apparatus is built for this experimental activity. Different geometrical configurations were investigated in order to find out which of them could maximize the heat transfer coefficient. Its dependence on some parameters as jet velocity, heat flux and distance between exit jet and wire is also examined. In the future the results of this paper will be compared with the previous ones presented in literature, referred to cylinders of one size order bigger than the platinum wire and the same slot, all parameters being equal.
Thermal Conductivity of One-Dimensional Silicon-Germanium Alloy Nanowires
Authors: Gwak Yunki , Narayanunni Vinay , Jee Sang-Won , Mavrokefalos Anastassios A. , Pettes Michael T. , Lee Jung-Ho , Shi Li , Yu Choongho
Published: June 2010

Thermal properties of one dimensional nanostructures are of interest for thermoelectric energy conversion. Thermoelectric efficiency is related to non dimensional thermoelectric figure of merit, ZT = (S^2 σT)/k where S, σ, k are the Seebeck coefficient, electrical conductivity and thermal conductivity respectively. These physical properties are interdependent, and hence making ZT of a material high is very challenging work. However, when the size of nanostructure is comparable to the wavelength and mean free path of energy carriers, it is feasible to avoid such interdependence to enhance ZT energy conversion. [1–3]
Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect
Authors: Parks J. J. , Champagne A. R. , Costi T. A. , Shum W. W. , Pasupathy A. N. , Neuscamman E. , Flores-Torres S. , Cornaglia P. S. , Aligia A. A. , Balseiro C. A. , Chan G. K.-L. , Abruña H. D. , Ralph D. C.
Published: June 2010

Spin Control Through Molecular Stretching

Molecules with high symmetry, such as metal complexes with several equivalent ligands, can, in principle, have this symmetry broken by stresses that lengthen bonds in one direction.

Parks
et al.

(p.
1370
; see the Perspective by
Jarillo-Herrero
) placed cobalt complexes in a break-junction contact and then applied a mechanical force to slowly open the contact. Low-temperature measurement of differential conductance revealed a splitting of the Kondo peak at zero-applied voltage into two features, which occurred by breaking the degeneracy of
S
= 1 triplet states. This assignment of the spin state was confirmed by the evolution of splitting with magnetic field and by comparison to theory for a case where the conduction electrons only partially screen the spin states.
Looking at Sexual Selection
Looking for a Few Good Males
Female Choice in Evolutionary Biology

by Erika Lorraine Milam

Johns Hopkins University Press, Baltimore, 2010. 246 pp. $60, £31.50. ISBN 9780801894190.
Authors: Rader Karen A.
Published: June 2010

Milam's history of sexual selection theory from about 1900 to about 1970 demonstrates that there was a lively interest in the topic during that period.