Surface energy balance closure by the eddy-covariance method above three boreal forest stands and implications for the measurement of the CO₂ flux   总被引：1，自引：1，他引：0  

A.G. Barr  K. Morgenstern  T.A. Black  J.H. McCaughey  Z. Nesic 《Agricultural and Forest Meteorology》2006,140(1-4):322

Closure of the surface energy balance provides an objective criterion for evaluating eddy-covariance (EC) flux measurements. This study analyses 5 years of EC carbon dioxide, water vapor, and sensible heat flux measurements from three mature boreal forest stands in central Saskatchewan, Canada. The EC sensible and latent heat fluxes, H and λE, underestimated the surface available energy by 11% (aspen), 15% (black spruce), and 14% (jack pine). At all sites, the energy-closure fraction CF responded similarly to the friction velocity u_*, atmospheric stability, and time of day. At night, CF increased from 0.3 at very low-u_* to an asymptotic maximum of 0.9 at u_* above 0.35 m s⁻¹. During unstable-daytime periods, CF varied linearly from 0.7 at low-u_* to 1.0 at high-u_*. The energy imbalance pattern was similar among sites and may be characteristic of the continental, boreal forest.EC measurements of net ecosystem exchange F_NEE have no objective, diagnostic parameter that is equivalent to CF. We therefore derived an analogous F_NEE “closure fraction” CF^NEE by normalizing measured F_NEE against estimates from an empirical model that was tuned to the high-u_* data. CF and CF^NEE responded similarly to u_*, atmospheric stability, and time of day. We discuss two implications for EC flux data post-processing. The results uphold the common practice of rejecting EC measurements during low-u_* periods. They also lend support to the application of energy-closure adjustments to H, λE, and F_NEE.  相似文献   

A retrospective study of the MRI findings in 18 dogs with stifle injuries     

E. Barrett    F. Barr    M. Owen    K. Bradley 《The Journal of small animal practice》2009,50(9):448-455

O bjectives : To make an objective assessment of the usefulness of magnetic resonance imaging in the diagnosis of meniscal damage and cranial cruciate ligament disease in the canine stifle by comparing magnetic resonance imaging findings with surgical findings.
M ethods : Magnetic resonance images of 18 stifles from 18 dogs which had undergone magnetic resonance imaging for the investigation of stifle disease were reviewed. For every stifle, the menisci and cranial cruciate ligaments were assessed according to predetermined criteria. The magnetic resonance imaging findings were compared with the reported surgical findings and the sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated using the surgical findings as the gold standard. Kappa analysis was used as an objective measure of agreement between surgical and magnetic resonance imaging findings. For 11 stifles, meniscal evaluation by three different observers was used to measure interobserver agreement using Kappa analysis.
R esults : Magnetic resonance imaging was demonstrated to be an accurate technique in the detection of meniscal injury (k=0·86), with excellent interobserver agreement (k=0·89 to 1·0). Disruption of cranial cruciate ligament continuity and an increase in ligament intensity were found to be useful criteria in the diagnosis of cranial cruciate ligament rupture.
C linical S ignificance : Magnetic resonance imaging offers a non-invasive alternative to exploratory surgery in the evaluation of cranial cruciate ligament and meniscal disease.  相似文献   

Destructive lesions of the proximal sesamoid bones as a complication of dorsal metatarsal artery catheterization in three horses     

Barr ED  Clegg PD  Mark Senior J  Singer ER 《Veterinary surgery : VS》2005,34(2):159-166

OBJECTIVE: To describe focal destructive lesions of the proximal sesamoid bones (PSBs) as a complication of dorsal metatarsal artery catheterization performed for direct blood pressure monitoring during equine general anesthesia. STUDY DESIGN: Retrospective study. ANIMALS: Three client-owned horses. METHODS: A dorsal metatarsal artery was catheterized in each of 3 horses for direct blood pressure monitoring during anesthesia. Radiography, ultrasonography, synoviocentesis, and arthroscopy were used to diagnose postoperative lameness that occurred in the limb used for blood pressure monitoring. RESULTS: Horses developed severe lameness, localized to the fetlock region of the catheterized limb within 21 days of surgery. Antibiotic therapy was administered. Surgical debridement was possible in 1 horse. Two horses that had lesions that were inaccessible, failed to respond to medical management and were euthanatized. The 3rd horse that had surgical debridement of affected bone, survived. Changes in hospital protocol, by improving aseptic technique during catheter insertion and use of new manometer tubing and heparinized saline for each arterial catheter inserted in the dorsal metatarsal artery, have eliminated this complication. CONCLUSIONS: Diagnosis and treatment of destructive lesions of the PSB were difficult. Strict aseptic technique should be followed during insertion of arterial catheters. CLINICAL RELEVANCE: Focal destructive lesions of the PSB subsequent to dorsal metatarsal arterial catheterization is a rare but serious complication of equine anesthesia.  相似文献   

Polymerase chain reaction screening for DNA viruses in paraffin-embedded brains from dogs with necrotizing meningoencephalitis, necrotizing leukoencephalitis, and granulomatous meningoencephalitis     

Schatzberg SJ  Haley NJ  Barr SC  de Lahunta A  Sharp NJ 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2005,19(4):553-559

The objective of this investigation was to determine whether or not herpesvirus (herpes-), adenovirus (adeno-), or canine parvovirus DNA is present in the brains of dogs with necrotizing meningoencephalitis (NME), necrotizing leukoencephalitis (NLE), and granulomatous meningoencephalitis (GME). Paraffin-embedded brain specimens from 12 histopathologically confirmed dogs with NME, 3 with NLE, and 7 with GME were screened for viral DNA with degenerate herpes- and adenovirus polymerase chain reaction (PCR) and a canine parvovirus-specific PCR. Positive-control specimens included genomic viral DNA and paraffin-embedded tissues from dogs with confirmed herpes-, adeno-, or canine parvovirus infections. Herpes-, adeno-, or canine parvovirus DNA was amplified by PCR from the corresponding positive-control specimens. Negative controls included 7 dogs with various brain disorders and produced no viral amplicons. The 22 dogs with NME, NLE, and GME were negative for viral DNA. Additional studies testing for other viruses or inherited genetic mutations are warranted to gain insight into the etiologies of NME, NLE, and GME. We discuss potential etiologies and provide a clinical and histopathologic overview of these common canine encephalitides.  相似文献   

Cloning and sequencing of the canine and feline cardiac troponin I genes     

Rishniw M  Barr SC  Simpson KW  Winand NJ  Wootton JA 《American journal of veterinary research》2004,65(1):53-58

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Septic flexor tendon core lesions in five horses     

Kidd JA  Dyson SJ  Barr AR 《Equine veterinary journal》2002,34(2):213-216

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Severe thrombocytopenia in 2 thoroughbred foals with sepsis and neonatal encephalopathy     

Bentz AI  Wilkins PA  MacGillivray KC  Barr BS  Palmer JE 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2002,16(4):494-497

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Effects of exercise on canine skeletal muscle proteolysis: an investigation of the ubiquitin-proteasome pathway and other metabolic markers     

Wakshlag JJ  Kallfelz FA  Barr SC  Ordway G  Haley NJ  Flaherty CE  Kelley RL  Altom EK  Lepine AJ  Davenport GM 《Veterinary therapeutics : research in applied veterinary medicine》2002,3(3):215-225

The effects of long-term athletic training are associated with excessive skeletal muscle turnover attributable to increased rates of myofibrillar protein synthesis and proteolysis, which are mechanisms poorly understood in the athletic dog. A physiologic field study using 44 English pointers and Labrador retrievers that had been purposely bred for bird hunting and retrieving was conducted to examine changes in the ubiquitin-proteasome (UP) pathway, which has been implicated in exercise-induced proteolysis. Muscle biopsy samples were collected from all dogs in September (preseason, pretraining) and February (peak season, peak activity). Western blot analysis was used to assess changes in expression of various components of the UP pathway in the biopsy samples. Citrate synthase and glycogen levels were also measured in a subset of these samples. Results across the population indicated pronounced up-regulation of ubiquitinated conjugates and the p31 regulatory capping subunit during the peak hunting period compared with the preseason period. In contrast, the catalytic core of the proteasome (beta-subunits) showed no apparent up-regulation in response to increased physical activity. Increased physical activity during the hunting season was associated with increased muscle glycogen levels and citrate synthase activity in these dogs. Overall, up-regulation of specific components of the UP pathway was an indication that it plays a role in the proteolytic process associated with skeletal muscle turnover during long-term athletic training, as previously believed.  相似文献   

Can owners assess outcome following treatment of canine cruciate ligament deficiency?   总被引：2，自引：0，他引：2  

J. F. Innes  A. R. S. Barr 《The Journal of small animal practice》1998,39(8):373-378

Forty-seven owners of 48 dogs surgically treated for cranial cruciate ligament deficiency were asked to assess the outcome of treatment at one year postsurgery. A standard visual analogue scale assessment tool was used in all cases and owners were asked to score a variety of generic and disease-specific features. The reliability and responsiveness of the assessment tool were estimated and found to be acceptable; generic features, such as 'level of disability', showed the greatest reliability and responsiveness. The results of assessments by owners were compared to assessments by a veterinary surgeon but few significant correlations were found. Assessments by owners appear to be a useful outcome measure in this disease but are unlikely to be directly comparable to assessments by a veterinary surgeon.  相似文献   

Clinical and scintigraphic findings in horses with a bone fragility disorder: 16 cases (1980-2006)     

Anderson JD  Galuppo LD  Barr BC  Puchalski SM  Macdonald MM  Whitcomb MB  Magdesian KG  Stover SM 《Journal of the American Veterinary Medical Association》2008,232(11):1694-1699

OBJECTIVE: To describe clinical and scintigraphic abnormalities in horses with a bone fragility disorder. DESIGN: Retrospective case series. ANIMALS: 16 horses with scintigraphic evidence of multiple sites of increased radiopharmaceutical uptake (IRU). Procedures-Medical records were reviewed for information on signalment; history; clinical, clinicopathologic, and diagnostic imaging findings; and treatment. Follow-up information was obtained through telephone interviews with owners. RESULTS: Horses ranged from 4 to 22 years old; there were 8 castrated males and 8 females. Foci of IRU most commonly involved the scapulae, ribs, sternebrae, sacral tubers, ilia, and cervical vertebrae. Most horses were examined because of chronic intermittent (n = 10) or acute (6) lameness involving a single (10) or multiple (6) limbs that could not be localized by means of regional anesthesia. Cervical stiffness (n = 3), scapular bowing (3), swayback (3), and ataxia (1) were also seen in more advanced cases. Signs of respiratory tract disease and exercise intolerance were evident in 4 horses. Ultrasonographic or radiographic evidence of bone remodeling or degeneration was seen in 19 of 33 affected bones. Histologic examination of bone biopsy specimens revealed reactive bone. Improvement was initially seen with conservative treatment in some horses, but the condition worsened in all horses, and 11 horses were euthanized within 7 years. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that horses may develop a bone fragility disorder characterized clinically by an unlocalizable lameness and scintigraphically by multiple sites of IRU involving the axial skeleton and proximal portion of the appendicular skeleton.  相似文献