Estimating biomass of white spruce seedlings with vertical photo imagery     

Ter-Mikaelian  Michael T.  Parker  William C. 《New Forests》2000,20(2):145-162

Estimation of individual tree seedling biomass isrequired in a variety of forest management andresearch applications such as assessment of netprimary productivity and carbon sequestrationpotential of forest stands, understory forest fuelinventories, and development of silviculturalguidelines to promote the growth of desired treespecies. Photo imagery is a promising non-destructivemethod for estimating the aboveground biomass of treeseedlings. This method was tested using naturallyregenerated white spruce (Picea glauca (Moench)Voss) seedlings growing in the understory of a mixedconifer shelterwood in central Ontario. In the fall of1997, 45 seedlings were sampled from plots exposed toone of three mechanical release treatments (earlyspring release, mid summer release, and no release(control)) in 1994. Each seedling was photographed inthe field to measure the vertical projected area(silhouette area) of the aboveground portion of theseedling. Seedlings were harvested, basal diameter andtotal height measured, and biomass (dry mass) offoliage, branches, main stem and total abovegroundplant tissue determined. Regression analysis revealeda strong relationship between both silhouette area andbasal diameter, and seedling biomass. Coefficients ofdetermination for regression equations usingsilhouette area were equal to 0.892, 0.918, 0.926, and0.937 for the main stem, branches, foliage, and totalaboveground biomass, respectively. Respectivecoefficients of determination for regression equationsusing basal diameter were 0.960, 0.945, 0.953, and0.977. Silhouette area-based equations for totalaboveground and foliar biomass differed significantly(P < 0.005) among release treatments. Nosignificant differences among treatments were observedbetween silhouette area-based equations for biomass ofbranches and main stem (P > 0.05), or betweenbasal diameter-biomass (allometric) equations for allcomponents (P > 0.1). The method was thentested by validating the biomass equations using anindependent data set from 35 white spruce seedlingsfrom the same site and cohort, but exposed todifferent treatments and microenvironmentalconditions. For each seedling, biomass components werepredicted using silhouette area-based and allometricequations, and a relative error of predictioncalculated. The mean relative error for silhouettearea-based predictions varied among biomass componentsfrom –20.25% to –3.21%, with standard deviation ofthe error ranging from 23.04% to 33.44%. The meanrelative error for allometric equations ranged from–2.46% to –21.75%, with standard deviations of23.34% to 32.61%. These results suggest that: (1)photo imagery can be used as an alternative to moretraditional allometric methods of biomass estimation,and (2) general (developed for a broad range ofgrowing conditions) equations derived by either methodare preferable to those specifically calibrated for agiven growing environment.  相似文献   

INCOMPLETE OSSIFICATION OF THE HUMERAL CONDYLE IN VIETNAMESE POT-BELLIED PIGS     

Valerie F.  Samii  DVM  William J.  Hornof  DVM  MS 《Veterinary radiology & ultrasound》2000,41(2):147-153

The purpose of this study was to evaluate the occurrence of humeral condylar fractures in Vietnamese pot-bellied pigs and to postulate a possible predisposing cause for these fractures. Thirteen Vietnamese pot-bellied pigs (Group A) were evaluated over an eight year period (1990-1998), each with a history of either a unilateral or bilateral forelimb lameness. The cause of lameness was localized to the elbow region. Of the thirteen pigs, twenty-one elbows were evaluated radiographically. Pigs ranged in age from six months to four years old. All pigs over the age of seven months showed radiographic evidence of elbow degenerative joint disease. Fractures involving the medial aspect of the humeral condyle were identified in 8/21 studies (38%). A well-defined linear intracondylar articular lucency was identified in 7/21 studies (33%) on the craniocaudal projection. The site of this lucency corresponded to the location of the articular component of the fractures seen involving the humeral condyle. The elbows of five pot-bellied pigs with no known history of forelimb lameness or trauma (Group B) were evaluated radiographically following euthanasia. All five pigs were of unknown age and gender. An intracondylar vertical linear lucency was identified bilaterally in three pigs (60%). Concurrent degenerative joint disease was present in all instances. The remaining two pigs were radiographically normal. Computed tomography of the elbows was performed in one affected pig from Group B. The radiographic findings in this pig were verified. Histopathology of the right elbow of this affected pig was diagnostic for incomplete endochondral ossification of the humeral condyle. A similar condition involving the humeral condyle has been previously described in Cocker and Brittany Spaniels. These canine breeds also have a high incidence of humeral condylar fractures. It is postulated that Vietnamese pot-bellied pigs are similarly prone to humeral condylar fractures, even in the absence of known trauma, due to incomplete ossification of the humeral condyle.  相似文献   

Radiographs Presented as Part of the 1999 ACVR Oral Certification Examination: Large Animal Imaging Elective     

William M.  Adams  DVM 《Veterinary radiology & ultrasound》2000,41(1):89-90

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BTEX Sorption by Montmorillonite Organo-Clays: TMPA,Adam, HDTMA     

Sharmasarkar  Shankar  Jaynes  William F.  Vance  George F. 《Water, air, and soil pollution》2000,119(1-4):257-273

Organo-clay can be utilized for the containment of environmentalpollutants originating from waste sites or accidental spills. Abatch study was conducted using organo-clays produced from aWyoming montmorillonite (SWy) and three organic cations(trimethylphenylammonium (TMPA), trimethylammonium adamantane(Adam), and hexadecyltrimethylammonium (HDTMA)) to characterizeBTEX (benzene, toluene, ethylbenzene, o-, m-, p-xylene) sorption. Sorption data were fitted to two models,with Freundlich resulting in greater correlations of the datathan the Langmuir model (R ² at P ≤0.001-0.05). The Freundlich conditional index (n _f),which describes the experimental sorption characteristics,decreased curvilinearly with organic-cation molecular weights,thus suggesting organo-clays with smaller cations had greaterhydrocarbon retention. Sorption of BTEX followed the order ofTMPA > Adam > HDTMA organo-clays. A similar sequence in themagnitudes of log K _d and log K _omsupportedthis finding. Positive log K _om/K _ow valuesfor TMPA and Adam derivatives indicated there was a greaterretention of BTEX by these organo-clays than octanol. The orderof log K _om for SWy-HDTMA, although concentration-dependent, was analogous to the log K _ow order,indicating partitioning was the dominant sorption mechanism forthe HDTMA-clay. Isotherms for SWy-TMPA and SWy-Adam followed aconvex up pattern. In contract, a concave up curvature, notedfor SWy-HDTMA isotherms, was probably caused by a cosorptiveenhancement process resulting from an effective increase in organic matter content of the organo-clay due to furtherhydrocarbon sorption,in concurrence with a decrease inadsorbate activity coefficients. Values of binding affinityconstant, K _f, for SWy-TMPA were consistently higherthan SWy-Adam. The K _f values determined for totalBTEX sorption by TMPA and Adam derivatives were higher thanthose for the individual hydrocarbons. With SWy-HDTMA, the same order was observed for benzene and toluene; however, ethylbenzene and xylenes had greater K _f values thanthat for the BTEX mixture, possibly due to higher partitioningaffinity of the larger alkylbenzenes. With SWy-HDTM, thesequence of K _f values was: ethylbenzene > m-xylene > p-xylene > o-xylene > toluene >benzene. Trends for SWy-TMPA and SWy-Adam were in contrast tothat of the partitioning order, suggesting that adsorption, ratherthan partitioning, was the primary sorption mechanism for thesetwo organo-clays. With respect to the equilibriumconcentrations, the sorbed amounts for total BTEX mixture weregenerally higher than those for the individual compounds. Ascompared to benzene and toluene, the large-size alkylbenzenesshowed greater partitioning affinity due to their high hydrophobicity.  相似文献   

Restoring fire-prone Inland Pacific landscapes: seven core principles     

Paul F. Hessburg  Derek J. Churchill  Andrew J. Larson  Ryan D. Haugo  Carol Miller  Thomas A. Spies  Malcolm P. North  Nicholas A. Povak  R. Travis Belote  Peter H. Singleton  William L. Gaines  Robert E. Keane  Gregory H. Aplet  Scott L. Stephens  Penelope Morgan  Peter A. Bisson  Bruce E. Rieman  R. Brion Salter  Gordon H. Reeves 《Landscape Ecology》2015,30(10):1805-1835

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Spine Protection in the Austere Environment     

Ken Zafren  William R. Smith  David E. Johnson  Tim Kovacs 《The Forestry Chronicle》2014,25(3):364-366

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The Two Cultures of Science： Implications for University-Industry Relationships in the U.S. Agriculture Biotechnology     

William B Lacy  Leland L Glenna  Dina Biscotti  Rick Welsh  Kate Clancy 《农业科学学报》2014,13(2):455-466

Partnerships between U.S. universities and industries have existed for several decades and in recent years have become generally more varied, wider in scope, more aggressive and experimental and higher in public visibility. In addition, in the last few decades, public and private interests have advocated for government policies and laws to globally promote the commercialization of university science. This paper examines the persistence or convergence of the two cultures of science and the implications of this commercialization for university-industry relationships in agriculture biotechnology. The perceptions and values of over 200 U.S. university and industry scientists, managers and administrators who participate in or oversee research collaborations in agricultural biotechnology were analyzed. The findings revealed that the participants in these research relationships continue to perceive very distinct cultures of science and identify a wide range of concerns and disadvantages of these partnerships. Several actions were discussed to ensure that the two cultures serve complementary roles and that they maximize the public benefits from these increasing collaborations.  相似文献   

Presence of residual material following mini-hemilaminectomy in dogs with thoracolumbar intervertebral disc extrusion     

Jonathan L. Huska  Luis Gaitero  Brigitte A. Brisson  Stephanie Nykamp  Jeff Thomason  William C. Sears 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(10):975-980

Presence of residual material following mini-hemilaminectomy in dogs (n = 9) with spontaneous thoracolumbar intervertebral disc extrusion was prospectively investigated. Volume of extruded disc material within the vertebral canal and the proportion of residual material were determined using pre- and post-operative magnetic resonance imaging. The degree of spinal cord compression, proportion of extradural material considered hemorrhage, and invasion of the articular facets were also determined. Residual material was identified in 44% of the mini-hemilaminectomies. The median percentage of residual material calculated was 7.7% of the preoperative volume. No observed effect of surgical side or site, proportion of extradural material considered hemorrhage, patient weight, and duration of clinical signs was detected.  相似文献   

Left ventricular radial colour and longitudinal pulsed-wave tissue Doppler echocardiography in 39 healthy domestic pet rabbits     

Domingo Casamian-Sorrosal  Richard Saunders  William Browne  Sarah Elliot  Sonja Fonfara 《Research in veterinary science》2014

This paper reports radial colour and longitudinal mitral annulus pulsed-wave tissue Doppler findings in a large cohort of healthy, adult pet rabbits. Thirty-nine rabbits (22 Dwarf Lops, 14 French Lops and three Alaskans) underwent conscious echocardiography. The median age of the rabbits was 22 months and the median weight was 2.8 kg (Dwarf Lop 2.4 kg/French Lop 6.0 kg). Adequate radial colour and longitudinal pulsed-wave tissue Doppler traces were obtained in 100% and 85% of cases, respectively. Most systolic tissue Doppler parameters were significantly higher in French Lops than in Dwarf Lops. Separation of mitral inflow diastolic waves was present in 40% of cases using conventional spectral Doppler and in >60% of cases using pulsed-wave tissue Doppler which could be beneficial when evaluating diastolic function in rabbits. This study can be used as a reference for normal echocardiographic tissue Doppler values for adult rabbits undergoing conscious echocardiography in clinical practice.  相似文献   

Evaluation of In Vivo Behavior of Ameroid Ring Constrictors in Dogs with Congenital Extrahepatic Portosystemic Shunts Using Computed Tomography     

Geraldine B. Hunt BVSc  PhD  FACVSc  William T. N. Culp VMD  Diplomate ACVS  Kelli N. Mayhew VMD  Diplomate ACVS  Philipp Mayhew BVM&S  Diplomate ACVS  Michele A. Steffey DVM  Diplomate ACVS 《Veterinary surgery : VS》2014,43(7):834-842

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