基于PhotoScan的径流小区三维重建参数优化   总被引：1，自引：0，他引：1  

张兴义  甄怀才  JAMES R Mike  杨薇  张晟旻  李浩 《农业机械学报》2019,50(12):144-150,230

提高径流小区数字地面模型精度是应用三维重建技术研究面蚀细沟间与细沟侵蚀过程的关键。以位于黑龙江省海伦市的中国科学院海伦水土保持监测研究站的裸地小区为研究对象,以验证点与控制点误差比和数字高程模型（Digital elevation model,DEM）误差为指标,优化Agisoft PhotoScan三维重建径流小区的处理参数,降低DEM误差。PhotoScan的精度参数和相机模型设置对DEM误差有较大影响。优化后的验证点与控制点误差比降低35%,改善了径流小区DEM对地面控制点的过度拟合。优化后的相机模型包含焦距、像主点、径向畸变、切向畸变等。基于单点和点云的验证结果表明,优化过程误差降低约40%。相对于默认参数设置下的验证点误差（20.0mm）,优化后的验证点误差为11.0mm,与细沟侵蚀深度标准相当（沟深大于等于10mm）,因此优化后的径流小区三维重建过程更适宜于细沟侵蚀过程的三维表达。  相似文献   

Estimates of South American Beef Export Multipliers     

JOHN W. ADAMS  JAMES R. SIMPSON 《Growth and change》1977,8(4):28-32

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Locational and Racial Variations in Poverty Incidence     

JAMES E. JONISH  JAMES B. KAU 《Growth and change》1976,7(1):24-27

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Virulence and aggressiveness of single-zoospore isolates of Phytophthora fragariae     

DIANA M. KENNEDY  JAMES M. DUNCAN  PATRICIA I. DUGARD  PAULINE H. TOPHAM 《Plant pathology》1986,35(3):344-354

A system for scoring the virulence of isolates of Phytophthora fragariae based on a scale of root rot from 0 ( no symptoms ) to 5 (76-100% roots roiled) on a series of strawberry cultivars is described. Thirty-two single-zoospore isolates from one field site were compared by subjecting their root rot scores to cluster analysis and this grouped them into two major clusters equivalent to physiologic races B66–3 and B66-11, Different sub-clusters of isolates of race B66-11 produced different degrees of rotting on the same hosts. Apart from differences in virulence between the sub-clusters there was some evidence for differences in aggressiveness between isolates within sub-clusters.
Increasing inoculum concentration by over 300-fold increased rotting by c . 25% but did not alter the rankings of different isolate/host combinations. Repeated passage of isolates through cultivars of differing susceptibilities did not affect their pathogenicity.  相似文献   

Cross reactions of an antiserum to plum pox potyvirus1     

D. JAMES  D. A. THOMPSON  S. E. GODKIN 《EPPO Bulletin》1994,24(3):605-614

In the early spring of 1992, plum pox-like viruses (PPLVs) were detected by standard ELISA in some Prunus species. The isolates reacted positively with plum pox potyvirus (PPV) antisera in immunosorbent electron microscopy and Western blot analysis. In Western blot analyses, bands associated with the coat protein subunits of the PPLVs were 48–56 kDa, whereas bands associated with the coat protein subunits of known PPV isolates were 32–37 kDa in size. Also, the PPLVs differed from known PPV isolates in their symptoms on woody and herbaceous indicators, and in their herbaceous host range. None of these PPLVs appears to be an isolate of PPV.  相似文献   

Laminotomy of the Axis for Surgical Access to the Cervical Spinal Cord A Case Report     

JAMES M. FINGEROTH DVM  DiplomateACVs  DANIEL D. SMEAK DVM  DiplomateACVS 《Veterinary surgery : VS》1989,18(2):123-129

A cranially hinged laminotomy of vertebra C2 was used to expose the cervical spinal cord of a dog with a meningioma in the region of the atlantoaxial articulation. By preserving the dorsal atlantoaxial ligament, the technique seemed to result in greater and more physiologic stability between the atlas and axis than dorsal laminectomy and prosthetic replacement of the dorsal atlantoaxial ligament. The procedure allowed a dorsal approach, avoiding injury to the vertebral arteries and limited exposure, which are potential problems with hemilaminectomy of C1-C2. Further investigation is needed to evaluate long-term consequences of this procedure.  相似文献   

Escape and avoidance learning in newly hatched domestic chicks     

JAMES H  BINKS C 《Science (New York, N.Y.)》1963,139(3561):1293-1294

Under the conditions specified, chicks fail to learn either to escape or to avoid shock on the day of hatching. Chicks trained for the first time on the day after hatching quickly learn to escape but do not learn to avoid shock. Avoidance learning first appears on the third day of life, and from that time the number of chicks learning to avoid increases with age, so that by the fifth day of life the majority are able to do so.  相似文献   

QUANTITATIVE CONTRAST ULTRASOUND ANALYSIS OF RENAL PERFUSION IN NORMAL DOGS   总被引：1，自引：1，他引：1  

KENNETH R. WALLER  ROBERT T. O''BRIEN  JAMES A. ZAGZEBSKI 《Veterinary radiology & ultrasound》2007,48(4):373-377

Eight normal dogs with no evidence of renal disease, weighing between 8 and 25 kg were imaged using contrast harmonic ultrasound after injection of a microbubble contrast medium. All dogs received three separate bolus injections of 0.05 ml of commercial contrast medium (Definity). Time/mean pixel value (MPV) curves were generated for selected regions in the cortex and medulla of the left kidney in each dog. Upslope, downslope, baseline, peak intensity, and time to peak were calculated for each zone. For a bolus injection, within the renal cortex (averaging all subjects) the upslope was 7.4 +/- 1.5 MPV/s, downslope was -0.4 +/- .2 MPV/s, baseline was 66.8 +/- 9.3 MPV, peak was 103.6 +/- 8.2 MPV, time to peak (from injection) was 12.8 +/- 5.3 s and from time of contrast medium reaching the kidney was 5.1 +/- 2.0 s. Within the renal medulla (averaging all subjects), upslope was 2.8 +/- 1.7 MPV/s, downslope was -0.3 +/- .2 MPV/s, baseline was 39.3 +/- 6.0 MPV, peak was 65.2 +/- 14.3 MPV, time to peak from injection was 20.9 +/- 6.4 s and from time of contrast reaching the kidney was 11.6 +/- 4.1 s. These baseline data may prove useful in the evaluation of dogs with diffuse disease or vascular compromise.  相似文献   

ULTRASONOGRAPHIC INTESTINAL HYPERECHOIC MUCOSAL STRIATIONS IN DOGS ARE ASSOCIATED WITH LACTEAL DILATION     

JAMES SUTHERLAND-SMITH  DOMINIQUE G. PENNINCK  JOHN H. KEATING  CYNTHIA R. L. WEBSTER 《Veterinary radiology & ultrasound》2007,48(1):51-57

In this retrospective study, the medical records of 23 dogs with the sonographic feature of small intestinal hyperechoic mucosal striations and an endoscopic or surgical intestinal biopsy were reviewed. Histopathologic lacteal dilation was present in 96% of dogs with mucosal striations. Sonographic findings associated with mucosal striations included: mild jejunal wall thickening (96%), mild duodenal wall thickening (78%), mucosal speckles (70%), and abdominal effusion (87%). The mucosal striations were diffuse (70%) or multifocal (30%) and did not cause loss of wall layering, except in one dog with a severe mural lipogranuloma. Mesenteric lymphadenopathy was identified in 9% of dogs. Thirteen dogs with endoscopic biopsies had mild to moderate villus lacteal dilation and the nine dogs with surgical biopsies had moderate to severe dilation. Inflammatory infiltrates were mild (61%) or moderate (30%) with variable numbers and combinations of cells, including eosinophils (65%), plasma cells (61%), lymphocytes (57%), and neutrophils (30%); one dog had disseminated villus histiocytic sarcoma. The biochemistry changes and clinical signs were consistent with protein-losing enteropathy in 78% of dogs. Hyperechoic mucosal striations in dogs are associated with lacteal dilation and are frequently associated with mucosal inflammation and protein losing enteropathy.  相似文献   

Biomechanical Comparison of the Herbert and AO Cortical Bone Screws for Compression of an Equine Third Carpal Bone Dorsal Plane Slab Osteotomy     

RACHEL C. MURRAY vetMB MS  Diplomate ACVS  Diplomate ECVS    EARL M. GAUGHAN DVM  Diplomate ACVS    RICHARD M. DEBOWES DVM  MS  Diplomate ACVS  JAMES J. HOSKINSON DVM  Diplomate ACVR 《Veterinary surgery : VS》1998,27(1):49-55

Objective—To assess feasibility of insertion of 4.5-mm Herbert cannulated bone screws (HS) using fluoroscopic guidance and compare the mechanical shear strength of these HS and 4.5-mm AO cortical bone screws (AO) for fixation of dorsal plane slab osteotomies in equine cadaver third carpal bones (C3).
Animals or Sample Population—Eight equine cadavers.
Methods—Bone mineral composition and density of contralateral C3 were confirmed to be equivalent using dual-energy x-ray absorptiometry. A standard 10-mm C3 slab osteotomy was reduced using HS or AO instrumentation under fluoroscopic guidance. Specimens were loaded in shear until failure, using a materials testing apparatus.
Results—HS and AO instrumentation allowed accurate reconstruction of the osteotomy, but there was difficulty encountered seating the HS proximal self-tapping threads. There was no significant difference in maximal load to failure, stiffness, or mode of failure of constructs created with the HS and AO screws.
Conclusions —Use of 4.5-mm HS for repair of C3 radial facet, dorsal plane slab fractures may result in a mechanically comparable fixation to a repair using a 4.5-mm AO. Equine dorsal C3 may be too dense, however, to allow placement of the proximal self-tapping threads of the HS without potentially excessive application of torque to the screw itself.
Clinical Relevance —Dorsal plane, radial facet slab fractures of the equine C3 are a significant clinical problem. Accurate reconstruction and stabilization are necessary for return to athletic function.  相似文献