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991.
Hannah Capes Robert J. Maillardet Thomas G. Baker Christopher J. Weston Don McGuire Ian C. Dumbrell Andrew P. Robinson 《Journal of Agricultural, Biological & Environmental Statistics》2017,22(4):562-584
The use of the allometric model \(y = \beta x ^{\alpha }\) to describe the relative growth of morphological traits of trees is a source of contention in ecology. This is particularly so in a specific form, the West, Brown and Enquist model, which predicts values of \(\alpha \) that are multiples of 1/4 for various allometric relationships—the quarter-power scaling law. We use statistical techniques to test the appropriateness of the quarter-power scaling allometric model in a number of different relative growth relationships of trees. Two separate datasets are used, one of repeated measures of Abies grandis (Grand fir) trees, another of independent measures of Eucalyptus trees. Nonlinear mixed-effects modelling is used to fit allometric models to the datasets. Generalised additive models, equivalence testing and traditional significance testing are used to assess the adequacy of the allometric models fitted and the values of the estimated exponents relative to those predicted by the WBE model. In only one of the five models fitted was there empirical evidence for the WBE-predicted quarter-power exponent. However, the adequacy of the allometric models was generally supported, though a need for further analysis over a larger range of tree ages/sizes is indicated.Supplementary materials accompanying this paper appear online. 相似文献
992.
Paolo Monticelli Ian Jones Jaime Viscasillas 《Veterinary anaesthesia and analgesia》2017,44(4):968-972
Objective
To describe an ultrasound-guided thoracic paravertebral block in canidae.Study design
Prospective, experimental, cadaveric study.Animals
Twelve thawed fox cadavers.Methods
A 15 MHz linear transducer was used to visualize the paravertebral space at the level of the fifth thoracic vertebrae. Iohexol (300 mg mL?1) at 0.2 mL kg?1 was injected into the right and left paravertebral spaces under ultrasound guidance using a Tuohy needle. The needle was advanced in a lateral to medial direction using an in-plane technique. Injections were performed by two operators, each performing 12 injections in six fox cadavers. A thoracic computed tomography was then performed and evaluated by a single operator. The following features were recorded: paravertebral contrast location (yes/no), length of contrast column (number of intercostal spaces), location of contrast relative to the fifth thoracic vertebrae (cranial/caudal/mixed), epidural contrast contamination (yes/no), pleural contrast contamination (yes/no) and mediastinal contrast contamination (yes/no).Results
All injections resulted in paravertebral contrast distribution (24/24). The mean length of the contrast column was five intercostal spaces. Contrast spread was caudal to the injection site in 54% (7/24), cranial in 29% (4/24) and mixed in 17% (3/24). Pleural contamination was observed in 50% (12/24) of injections; 42% (10/24) and 4% (1/24) of the injections resulted in mediastinal and epidural contamination, respectively.Conclusions and clinical relevance
Injection of the paravertebral space in canidae is possible using the technique described. Possible complications include epidural, pleural and mediastinal contamination. To establish clinical efficacy and safety of this technique, further studies are required. 相似文献993.
Further characterization of computed tomographic and clinical features for staging and prognosis of idiopathic pulmonary fibrosis in West Highland white terriers
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994.
The increased rate of human-driven change is a major threat to biodiversity. Although there is sufficient evidence to suggest that species notably alter their ranges, facilitation of such movement for larger vertebrate species often places burdens on management agencies. Oribi antelope (Ourebia ourebi ourebi) in South Africa continue to experience dramatic decreases in range and numbers. Animals have and continue to be translocated for conservation, but also aesthetic and financial reasons. Initial translocations were done in the absence of any thought or understanding of genetic structure, while for the past two decades a conservative best-practice approach was adopted, but in the absence of any specific genetic information. Here, we use two mitochondrial and one nuclear fragment to report the phylogeographic structure in oribi antelope across South Africa. Our data indicate that the South African subspecies is distinct from other subspecies to the north, confirming that oribi in South Africa should be managed as a distinct conservation unit. Across the South African range, high genetic diversity is present with some evidence for genetic structure (phylogenetic trees and haplotype networks). However, there is no spatial component to the diversity (non-significant p-values in AMOVA analyses), possibly because of historic translocations. We evaluate translocation approaches currently in place, and make specific and general recommendations for future conservation management based on an improved understanding of population genetic diversity and genetic structure. 相似文献
995.
Jiangyong Zeng Ciren Duoji Zhenjie Yuan Silang Yuzhen Weixing Fan Lili Tian Chang Cai Ian Robertson 《Tropical animal health and production》2017,49(7):1339-1344
A cross-sectional study was conducted in three counties (Damxung, Maizhokunggar and Yadong) in Tibet in April and May 2015. A total of 1,523 yaks owned by 181 herders were randomly selected and blood sampled. Sera were tested using the rose bengal test (RBT) and a competitive immune-enzymatic assay (C-ELISA) and the test results interpreted in parallel. The individual yak prevalence was 2.8% (95% CI 2.0–3.7) with a herd prevalence of 18.2% (95% CI 12.9–24.6). At the individual level, two predictor variables, age and production system, were significantly associated with seropositivity by a binary logistic regression analysis. The odds of Brucella infection were significantly higher in older Yaks (3–5 years old, OR = 4.51; 95% CI 1.53–19.29; ≥6 years old, OR = 3.89; 95% CI 1.23–17.21) compared to those of younger yaks (≤2 years old). The odds of seropositivity for yaks managed under an agro-pastoral production system were 2.9 (95% CI 1.48–5.86) times higher compared to those managed under a pastoral production system. At the herd level, an association between the infection with Brucella and a history of abortions in the herd was observed (OR = 4.98, 95% CI 1.48–16.62). Surprisingly, vaccination was not associated with a lower level of infection (p = 0.49 and p = 0.99 for individual and herd level data, respectively). The results of the survey indicate that bovine brucellosis is endemic among the yak population in the plateau region of China, and the risk factors identified in the study should be considered in the epidemiology of the disease and when developing control programs for the disease. 相似文献
996.
Seiler GS Robertson ID Mai W Widmer WR Suran J Nemanic S Lamb CR Lang J Johnson JL Thrall DE 《Veterinary radiology & ultrasound》2012,53(2):157-161
Single-shot turbo spin-echo sequences are heavily T2-weighted sequences that are exceptionally well suited to evaluate the subarachnoid space. In the T2-weighted fast spin-echo sequences that are used routinely in spinal magnetic resonance (MR) imaging, the subarachnoid space is not well differentiated from the surrounding epidural fat, which could lead to decreased detection of lesions of the subarachnoid space such as arachnoid diverticula. Our purpose was to determine the added value of a single-shot turbo spin-echo sequence in identifying cystic lesions of the subarachnoid space in dogs. MR images of six dogs with a confirmed arachnoid diverticulum and 24 dogs with other spinal disease were included. Six observers were asked to interpret only T2-weighted images initially, and in a second session, T2-weighted and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. The MR images were anonymized, and no signalment, history, or clinical information was provided. Without the HASTE sequences, 25% of arachnoid diverticula were identified. Adding the HASTE sequence increased the diagnosis of arachnoid diverticulum to 52.8%. The resulting difference, after adding the HASTE sequence, of 27.8% was statistically significant (P = 0.002). No false-positive diagnoses of arachnoid diverticulum were made with either sequence. Although sensitivity in this study was likely artificially low, the significantly increased detection rate of arachnoid diverticula when using HASTE imaging indicates that this sequence is a valuable addition to MR imaging protocols for the canine spine. 相似文献
997.
N Webb D Cseh E Lenc O Godet D Barret S Corbel S Farrell R Fender N Gehrels I Heywood 《Science (New York, N.Y.)》2012,337(6094):554-556
Relativistic jets are streams of plasma moving at appreciable fractions of the speed of light. They have been observed from stellar-mass black holes (~3 to 20 solar masses, M(⊙)) as well as supermassive black holes (~10(6) to 10(9) M(⊙)) found in the centers of most galaxies. Jets should also be produced by intermediate-mass black holes (~10(2) to 10(5) M(⊙)), although evidence for this third class of black hole has, until recently, been weak. We report the detection of transient radio emission at the location of the intermediate-mass black hole candidate ESO 243-49 HLX-1, which is consistent with a discrete jet ejection event. These observations also allow us to refine the mass estimate of the black hole to be between ~9 × 10(3) M(⊙) and ~9 × 10(4) M(⊙). 相似文献
998.
MT Maurano R Humbert E Rynes RE Thurman E Haugen H Wang AP Reynolds R Sandstrom H Qu J Brody A Shafer F Neri K Lee T Kutyavin S Stehling-Sun AK Johnson TK Canfield E Giste M Diegel D Bates RS Hansen S Neph PJ Sabo S Heimfeld A Raubitschek S Ziegler C Cotsapas N Sotoodehnia I Glass SR Sunyaev R Kaul JA Stamatoyannopoulos 《Science (New York, N.Y.)》2012,337(6099):1190-1195
999.
A mechanism of extreme growth and reliable signaling in sexually selected ornaments and weapons 总被引:1,自引:0,他引:1
Many male animals wield ornaments or weapons of exaggerated proportions. We propose that increased cellular sensitivity to signaling through the insulin/insulin-like growth factor (IGF) pathway may be responsible for the extreme growth of these structures. We document how rhinoceros beetle horns, a sexually selected weapon, are more sensitive to nutrition and more responsive to perturbation of the insulin/IGF pathway than other body structures. We then illustrate how enhanced sensitivity to insulin/IGF signaling in a growing ornament or weapon would cause heightened condition sensitivity and increased variability in expression among individuals--critical properties of reliable signals of male quality. The possibility that reliable signaling arises as a by-product of the growth mechanism may explain why trait exaggeration has evolved so many different times in the context of sexual selection. 相似文献
1000.
Certain human pathogens avoid elimination by our immune system by rapidly mutating the surface protein sites targeted by antibody responses, and consequently they tend to be problematic for vaccine development. The behavior described is prominent for a subset of viruses--the highly antigenically diverse viruses--which include HIV, influenza, and hepatitis C viruses. However, these viruses do harbor highly conserved exposed sites, usually associated with function, which can be targeted by broadly neutralizing antibodies. Until recently, not many such antibodies were known, but advances in the field have enabled increasing numbers to be identified. Molecular characterizations of the antibodies and, most importantly, of the sites of vulnerability that they recognize give hope for the discovery of new vaccines and drugs. 相似文献