Comparison of ultrasound, computed tomography, and magnetic resonance imaging in detection of acute wooden foreign bodies in the canine manus

We evaluated the diagnostic sensitivity of ultrasound, nonenhanced computed tomography (CT) and nonenhanced magnetic resonance (MR) imaging in detecting wooden foreign bodies in the canine manus. Identical wooden splinters were manually inserted into 30 cadaver canine manus, and the limbs were evaluated using ultrasound, CT, and MR imaging by independent observers. All sites were rated as positive or negative for the presence of a foreign body, and observer certainty was scored on a 1-10 scale. Using receiver operating characteristic analysis, CT was the most accurate modality for detection of wooden foreign bodies overall and within each of the three individual regions, followed by ultrasound and MR imaging, respectively. Ultrasound evaluations were most limited in the metacarpal pad, where distal acoustic shadowing from the pad surface hindered evaluation of the tissues in some specimens.     

Detection of plant pathogens using real‐time PCR: how reliable are late Ct values?

Effective detection of pathogens from complex substrates is a challenging task. Molecular approaches such as real‐time PCR can detect pathogens present even in low quantities. However, weak real‐time PCR signals, as represented by high cycle threshold (C_t) values, may be questionable. Therefore, setting a reliable C_t threshold to declare a positive reaction is important for specific detection. In this study, five methods were assessed for their performance in determining a C_t cut‐off value. These methods were based on the widely used probability of detection (POD) or receiver‐operating characteristic (ROC) approaches. Two important forest pathogens, Hymenoscyphus fraxineus and Fusarium circinatum, were used to set up three experimental frameworks that combined two types of substrates (seed lots and spore traps) and different PCR machines. The ROC‐based method emerged as the most complete and flexible method under various experimental conditions. It was demonstrated that the ROC method leads to a cut‐off value below which late C_t results can reliably be considered indicative of positive test results. This cut‐off value must be determined for each experimental approach used. The method based on the distribution of a previously determined set of C_t values corresponding to false‐positives appeared to be better adapted to detecting false‐negative results, and thus useful for testing potentially invasive pathogens.     

Multipath interference cancellation RAKE receiver with nested structure

A multipath interference cancellation RAKE receiver with nested structure is proposed based on successive interference cancellation method. In the proposed method, the present branch and the demodulated branch form a substructure of the RAKE receiver, while the RAKE substructures are nested. The data estimate of the present branch is obtained by the maximum ratio combination of the demodulator output in the corresponding RAKE substructure. The update of the regeneration signal is achieved by replacing the previous branch data with the present branch data estimate . Performance of the new RAKE receiver was analyzed. Theoretical analysis and simulation results show that the new RAKE receiver with simple structure and easy implementations can suppress the multipath interference and improves the BER performance.     

手持型GPS接收机面积测量精度研究

在理论分析手持型GPS接收机面积测量原理的基础上,对9个不同大小地块在不同时段、不同干扰条件下实际面积测量的精度进行分析,详细论证了手持型GPS接收机完全能够满足退耕还林、造林地验收、小班面积测量等精度的需要,可广泛应用于森林资源调查.     

Evaluation of modified Wright-staining of dried urinary sediment as a method for accurate detection of bacteriuria in cats

Background: Urinary sediment examination and quantitative urinary culture results are frequently discordant. Objectives: The aims of this study were to compare accuracy of light microscopic examination of wet‐mounted unstained (wet‐unstained) and air‐dried modified Wright‐stained (dry‐stained) sedimented preparations of urine with results of quantitative aerobic bacterial culture for detection and characterization of bacteriuria in cats. In addition, the presence of pyuria detected by urinalysis and potential risk factors were assessed. Methods: A blinded prospective study was conducted on 472 urinary samples collected from 410 cats by cystocentesis. The age and sex of each cat were recorded. Complete urinalyses were performed and included quantification of WBCs. Quantity and morphology of bacteria in each specimen were determined by light microscopic examination of wet‐unstained (performed by certified medical technologists) and dry‐stained (performed by a veterinary clinical pathologist) sedimented preparations of urine and compared with results of quantitative bacterial cultures. Results: Of 472 urinary specimens, 29 were positive for bacteriuria by culture and considered true positives and 443 were considered true negatives. Compared with these results, examination of wet‐unstained and dry‐stained urines had sensitivities of 75.9% and 82.8%, specificities of 56.7% and 98.7%, and test efficiencies of 57.8% and 97.7%, respectively. Positive likelihood ratios were 1.8 and 63.7 and negative likelihood ratios were 0.42 and 0.17 for wet‐unstained and dry‐stained examinations, respectively. Compared with 29 culture‐positive samples, the wet‐unstained method had morphologic concordance and misclassification rates of 37.9% and 62.1%, respectively, whereas the dry‐stained method had morphologic concordance and misclassification rates of 65.5% and 34.5%, respectively. Only 34% of samples with bacteriuria had pyuria. Frequency of bacteriuria was not significantly different based on age and sex of the cats, but there was a tendency for increased frequency in female cats and in cats >10 years old. Conclusions: Staining dried urinary sediment with a modified Wright‐stain significantly improved sensitivity, specificity, and test efficiency of microscopic detection and classification of bacteriuria compared with the wet‐unstained method. Pyuria should not be a criterion for determining the presence or absence of bacteriuria.     

CORS手持GPS接收机在架空输电线路中的应用探讨

介绍了CORS手持GPS接收机在架空输电线路测量工作中的应用试验。通过试验表明：在架空输电线路终勘过程中，CORS手持接收机测量结果能够满足选线的各项精度要求，同时，CORS技术能够提高劳动生产率，节省施工成本。     

The reliability of leaf bioassays for predicting disease resistance on fruit: a case study on grapevine resistance to downy and powdery mildew

This study was designed to assess the reliability of grapevine leaf bioassays for predicting disease resistance on fruit in the field. The efficacy of various grapevine quantitative trait loci (QTLs) for conferring resistance to downy and powdery mildew was evaluated in bioassays and in a 2‐year field experiment for downy mildew. The resistance genes studied were inherited from Muscadinia rotundifolia (Rpv1 and Run1) and from American Vitis species through cv. Regent (QTLRgP and QTLRgD). In bioassays, genotypes carrying Run1 blocked powdery mildew development at early stages. Genotypes combining Run1 with QTLRgP displayed no greater level of resistance. For downy mildew, genotypes carrying Rpv1 and/or QTLRgD were more resistant than the susceptible cv. Merlot, and showed a high level of leaf resistance in the field (<10% severity). Disease levels on bunches were much higher than those on leaves, with a high variability between Rpv1 genotypes (1–48%). A Bayesian decision theory framework predicted that an OIV‐452 threshold of 5 in leaf bioassays allowed accurate selection of grapevine genotypes (P = 0·83) with satisfactory disease severity on bunches. Therefore, this study validates that the use of early bioassays on leaves, as currently performed by grapevine breeders, ensures a satisfactory level of resistance to downy mildew of bunches in the field.     

基于手持式GPS接受机的林区坐标差分研究

本文研究我国林业应用较多的手持式GPS接收机用手坐标差的原理、技术和方法。文章建立了基于基准站两个历元之间的直线内插模型和三个历元的抛线内插模型 ,并编制相应的VB计算程序 ,通过麦哲伦GPS2 0 0实测验证 :对于 9874 5 4 1m2 地林面积 ,采用GPS单机定位 ,其相对误差为 19 0 0 % ,而采用直线内插、抛物线内插法差分定位其面积误差为 3 0 0 %和 1 91% ,其实测定精度为 :单机± 4 9m ,直线内插差分法±3 0m ;抛物线内插法差分± 2 8m。     

Summary receiver operating characteristics (SROC) and hierarchical SROC models for analysis of diagnostic test evaluations of antibody ELISAs for paratuberculosis

Critical, systematic reviews of available diagnostic test evaluations are a meticulous approach to synthesize evidence about a diagnostic test. However, often the review finds that data quality is poor due to deficiencies in design and reporting of the test evaluations and formal statistical comparisons are discouraged. Even when only simple summary measures are appropriate, the strong correlation between sensitivity and specificity and their dependence on differences in diagnostic threshold across studies, creates the need for tools to summarise properties of the diagnostic test under investigation.This study presents summary receiver operating characteristics (SROC) analysis as a means to synthesize information from diagnostic test evaluation studies. Using data from a review of diagnostic tests for ante mortem diagnosis of paratuberculosis as an illustration, SROC and hierarchical SROC (HSROC) analysis were used to estimate overall diagnostic accuracies of antibody ELISAs for bovine paratuberculosis while accounting for covariates: the target condition (infectious or infected) used in the test evaluation (one for the evaluation of Se and one for Sp); and the type of test (serum vs. milk). The methods gave comparable results (regarding the estimated diagnostic log odds ratio), considering the small sample size and the quality of data. The SROC analysis found a difference in the performance of tests when the target condition for evaluation of Se was infected rather than infectious, suggesting that ELISAs are not suitable for detecting infected cattle. However, the SROC model does not take differences in sample size between study units into account, whereas the HSROC allows for both between and within study variation. Considering the small sample size, more credibility should be given to the results of the HSROC. For both methods the area under the (H)SROC curve was calculated and results were comparable.The conclusion is that while the SROC is simpler and easier to implement, analyse and interpret, the HSROC does have properties encourage the extra effort involved in the analysis.     

15种阔叶树材中切削厚度、刀具前角和木材含水率对切削阻力的影响

１５种阔叶树材切削厚度、刀具前角和木材含水率对切削阻力的影响进行了研究。针叶树材不同树种中此三因素对切削阻力影响的规律，在阔叶树材中有相似表现。在气干到充分吸湿阶段中，含水率对切削阻力影响的趋势在针叶材和阔叶材中有所不同。