Influence of site,storage and steaming on <Emphasis Type="Italic">Eucalyptus nitens</Emphasis> log-end splitting     

Mario Vega  Matthew G. Hamilton  David P. Blackburn  Robert L. McGavin  Henri Baillères  Brad M. Potts 《Annals of Forest Science》2016,73(2):257-266

  相似文献   

Complexity in modelling forest ecosystems: How much is enough?   总被引：1，自引：0，他引：1  

James P. Kimmins  Juan A. Blanco  Brad Seely  Clive Welham  Kim Scoullar 《Forest Ecology and Management》2008

The levels-of-integration concept in ecology suggests that while the population and community levels of biological organization provide understanding, they do not provide an adequate basis for predicting future states of populations, communities or ecosystems. Empirical models of populations and communities are implicitly ecosystem level because they are based on measures of the results of all past determinants that affected the populations and communities in question. They can be good predictors under unchanging conditions, but they are not able to predict for changing conditions, which requires the explicit representation of those ecological processes that are anticipated to change. The question addressed in this paper is: how does the performance of a “simple” stand-level model change as representations of these processes are added, and how much complexity is enough? Examples are given of change in performance of the ecosystem management model FORECAST run as a light competition model as nutrient regulation of growth and understory interactions are added singly or in combination. These examples are framed in comparisons of simulations for a white spruce stand in the in boreal mixedwood region in northern British Columbia, for a long-term thinning-fertilization trial in a Douglas-fir stand on southern Vancouver Island, and for yield decline in Chinese fir in south eastern China. It is concluded that the effect of adding complexity on the predictions of this model depends on the time scale of the simulation and the management or natural disturbance regime that is being simulated. The results supported Occam's razor: that models should be as simple as possible but as complex as necessary.  相似文献   

Confidence intervals for the difference of two proportions estimated from pooled samples     

Brad J Biggerstaff 《Journal of Agricultural, Biological & Environmental Statistics》2008,13(4):478-496

This article presents confidence intervals for the difference of two binomial proportions estimated from pooled samples with unequal pool sizes. Asymptotic methods are used to derive Wald, profile score, and profile likelihood ratio intervals. Corrections for bias and skewness of the distribution of the Studentized score statistic are used to improve the profile score interval. Further, the easily computed Wilson score-based interval of Newcombe is adapted. Coverage and noncoverage probabilities and expected lengths of the confidence intervals are estimated for a range of parameter values expected in application, for both one- and two-sample cases. The skewness-corrected profile score interval is generally recommended. The methods are applied to a comparison of West Nile virus mosquito infection prevalences by trapping height in field collections from Louisiana in 2003.  相似文献   

Genetic correlations between pulpwood and solid-wood selection and objective traits in Eucalyptus globulus     

Matthew G. Hamilton  Brad M. Potts  Bruce L. Greaves  Greg W. Dutkowski 《Annals of Forest Science》2010,67(5):511-511

? If selective breeding is to be successful, significant genetic variation must be present in the traits targeted for improvement (i.e. “objective traits”).

? This study aimed to quantify genetic variation in Eucalyptus globulus pulpwood and sawn-timber objective traits (rotation-age whole-tree volume, survival, whole-tree basic density, sawn-board Janka hardness and sawn-board internal checking) and estimate additive genetic correlations between these and inexpensively-assessed “selection traits”.

? Significant genetic variation was identified in all objective traits at the subrace and/or family within subrace level.

? Selection-age diameter at breast height (1.3 m, DBH) was strongly genetically correlated with rotation-age volume (0.78) and survival (0.82). Subrace and additive genetic correlations of selectionage Pilodyn penetration with rotation-age 12-×-12-mm-sample basic density (?0.70 and ?0.75 respectively) and whole-tree basic density (?0.83 and ?0.91 respectively) were also strong.

? No significant subrace or additive genetic correlation between wood-sample gross shrinkage and sawn-board internal checking was detected. However, subrace and additive genetic correlations of sawn-board Janka hardness with Pilodyn penetration (?0.75 and ?0.58 respectively) and sample gross shrinkage (?0.77 and ?0.73 respectively) were significantly different from zero.

? These findings suggest that genetic improvement of the examined objective traits is possible through selective breeding, although none of the assessed selection traits were strongly correlated with internal checking.

  相似文献   

Glucose and weight control in mice with a designed ghrelin O-acyltransferase inhibitor     

Barnett BP  Hwang Y  Taylor MS  Kirchner H  Pfluger PT  Bernard V  Lin YY  Bowers EM  Mukherjee C  Song WJ  Longo PA  Leahy DJ  Hussain MA  Tschöp MH  Boeke JD  Cole PA 《Science (New York, N.Y.)》2010,330(6011):1689-1692

Ghrelin is a gastric peptide hormone that stimulates weight gain in vertebrates. The biological activities of ghrelin require octanoylation of the peptide on Ser(3), an unusual posttranslational modification that is catalyzed by the enzyme ghrelin O-acyltransferase (GOAT). Here, we describe the design, synthesis, and characterization of GO-CoA-Tat, a peptide-based bisubstrate analog that antagonizes GOAT. GO-CoA-Tat potently inhibits GOAT in vitro, in cultured cells, and in mice. Intraperitoneal administration of GO-CoA-Tat improves glucose tolerance and reduces weight gain in wild-type mice but not in ghrelin-deficient mice, supporting the concept that its beneficial metabolic effects are due specifically to GOAT inhibition. In addition to serving as a research tool for mapping ghrelin actions, GO-CoA-Tat may help pave the way for clinical targeting of GOAT in metabolic diseases.  相似文献   

Total laparoscopic gastropexy using 1 simple continuous barbed suture line in 63 dogs          下载免费PDF全文

Joel D. Takacs  Ameet Singh  J. Brad Case  Philipp D. Mayhew  Michelle A. Giuffrida  Ana V. Caceres  W. Alexander Fox‐Alvarez  Jeffrey J. Runge 《Veterinary surgery : VS》2017,46(2):233-241

  相似文献   

Mollicutes species and Mycoplasma bovis prevalence and association with health outcomes in beef feeder calves at arrival and initial treatment for bovine respiratory disease     

White BJ  Hanzlicek G  Sanderson MW  Anderson DE  Larson RL 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(9):1016-1018

Mollicutes nasal swab culture status and potential associations with health outcomes were determined in beef feeder calves. Mollicutes culture was positive in 7.6% (22/291) of calves at arrival and in 26.2% (34/130) of calves at first disease treatment. Positive Mollicutes culture at first treatment was associated with increased odds for subsequent retreatment or death.  相似文献   

The cosmic production of helium     

Jimenez R  Flynn C  MacDonald J  Gibson BK 《Science (New York, N.Y.)》2003,299(5612):1552-1555

We estimate the cosmic production rate of helium relative to metals (DeltaY/DeltaZ) using K dwarf stars in the Hipparcos catalog with accurate spectroscopic metallicities. The best fitting value is DeltaY/DeltaZ = 2.1 +/- 0.4 at the 68% confidence level. Our derived value agrees with determinations from H II regions and with theoretical predictions from stellar yields with standard assumptions for the initial mass function. The amount of helium in stars determines how long they live and therefore how fast they will enrich the interstellar medium with fresh material.  相似文献   

United States Department of Agriculture-Agricultural Research Service research on natural products for pest management     

Duke SO  Baerson SR  Dayan FE  Rimando AM  Scheffler BE  Tellez MR  Wedge DE  Schrader KK  Akey DH  Arthur FH  De Lucca AJ  Gibson DM  Harrison HF  Peterson JK  Gealy DR  Tworkoski T  Wilson CL  Morris JB 《Pest management science》2003,59(6-7):708-717

Recent research of the Agricultural Research Service of USDA on the use of natural products to manage pests is summarized. Studies of the use of both phytochemicals and diatomaceous earth to manage insect pests are discussed. Chemically characterized compounds, such as a saponin from pepper (Capsicum frutescens L), benzaldehyde, chitosan and 2-deoxy-D-glucose are being studied as natural fungicides. Resin glycosides for pathogen resistance in sweet potato and residues of semi-tropical leguminous plants for nematode control are also under investigation. Bioassay-guided isolation of compounds with potential use as herbicides or herbicide leads is underway at several locations. New natural phytotoxin molecular target sites (asparagine synthetase and fructose-1,6-bisphosphate aldolase) have been discovered. Weed control in sweet potato and rice by allelopathy is under investigation. Molecular approaches to enhance allelopathy in sorghum are also being undertaken. The genes for polyketide synthases involved in production of pesticidal polyketide compounds in fungi are found to provide clues for pesticide discovery. Gene expression profiles in response to fungicides and herbicides are being generated as tools to understand more fully the mode of action and to rapidly determine the molecular target site of new, natural fungicides and herbicides.  相似文献   

Genetic Analyses for TSV-Susceptible and TSV-Resistant Pacific White Shrimp Litopenaeus vannamei using M1 Microsatellite     

Zhenkang  Xu  Jennifer  Wyrzykowski Acacia  Alcivar-Warren Shaun M.  Moss  Brad J.  Argue  Steve M.  Arce  Monica  Traub Fernanda R. O.  Calderon Jeffrey  Lotz Verlee  Breland 《Journal of the World Aquaculture Society》2003,34(3):332-343

Allelic frequency differences at the highly polymorphic MI microsatellite of B20 locus were examined in Taura Syndrome Virus (TSV)-susceptible (Kona) and TSV-resistant (Select) lines of Pacific white shrimp Litopenaeus vannamei . DNA was screened from 1,009 cultured L. vannamei , 166 from the Kona line and 843 (97 broodstock and 746 offspring) from the Select line. A total of 34 different MI alleles were found, 41.2% of which were shared by the two lines, and 58.2% were unique to either line. Only seven (20.6%) of the 34 alleles had similar frequencies in the two lines. The most frequent (22.4%) allele in the Select line (218 bp) was absent from the Kona line. The most frequent (9.6%) allele in the Kona line (236 bp) was not observed in the Select line. Significant genetic differentiation between the two lines was shown using contingency table analysis (X²= 891.20, df = 33, P < 0.0001), the exact test ( P < 0.00001), and F_st, analysis (0.06). Comparison of MI allele frequencies between the TSVresistant Select and TSV-susceptible Kona lines and between the top 12.5% (Top Select) and the bottom 12.5% (Bottom Select) surviving families to TSV challenge in the Select line suggested associations of MI alleles with TSV resistance. These observations suggest testable hypotheses in future experiments aimed at finding genetic markers associated with resistance to TSV and markers that could be used for marker-assisted selection of broodstock.  相似文献