Threshold Firms: Innovation,Design and Collaboration in British Columbia's Forest Economy          下载免费PDF全文

Rosemary Hanna  Roger Hayter  Alex Clapp 《Growth and change》2017,48(4):700-718

This paper assesses the extent to which threshold firms have emerged within British Columbia's wood processing industries. Threshold firms comprise an innovative business segment and are growth oriented, larger than most small firms but not giant, locally owned, international in scope at least with respect to exporting, reliant on skilled, well paid employees, and that have developed knowledge‐based product market advantages. The analysis draws on an extended case study survey of 14 firms located in the lower mainland and Okanagan regions of British Columbia, and selected for their potential as threshold firms. The analysis examines six characteristics associated with threshold firms: size and ownership, internationalization, wood supply, labor relations, innovative design and collaboration, and local embeddedness. These firms reveal attributes of threshold firms, and the paper concludes by suggesting that an innovative forest policy for British Columbia could usefully focus on this type of firm.  相似文献   

Inheritance of type IV glandular trichome density and its association with whitefly resistance from <Emphasis Type="Italic">Solanum galapagense</Emphasis> accession LA1401     

Marcela Carvalho Andrade  Alex Antônio da Silva  Irã Pinheiro Neiva  Izabela Regina C. Oliveira  Evaristo Mauro De Castro  David Merrill Francis  Wilson Roberto Maluf 《Euphytica》2017,213(2):52

Tomato is affected by a large number of arthropod pests, among which the whitefly (Bemisia tabaci) is considered to be one of the most destructive. Several accessions of the wild species of Solanum galapagense, including accession LA1401, are considered resistant to whitefly (B. tabaci). This resistance has been associated with the presence of type IV glandular trichomes on the leaf surface. Our research aimed to study the inheritance of type IV glandular trichome density and its association with resistance to whitefly (B. tabaci biotype B) in populations derived from the interspecific cross Solanum lycopersicum × S. galapagense ‘LA1401.’ High estimates for both broad-sense and narrow-sense heritabilities of type IV glandular trichome densities suggest that inheritance of this trait is not complex. Whitefly resistance was associated with high density of type IV glandular trichomes. F₂ (S. galapagense × S. lycopersicum) population plants selected for the highest densities of type IV glandular trichomes showed similar levels of resistance to those found in the donor of resistance LA1401.  相似文献   

Is the use of turmeric in the diet safe for fish?          下载免费PDF全文

Pollyanna de Moraes França Ferreira  Suellen Silva Condessa  Juliana Silva Rocha  Débora Werneck Caldas  Juliana Rodrigues Gomes  Maria Tatiana Soares  Alex Junio Silva Cardoso  Jener Alexandre Sampaio Zuanon 《Aquaculture Research》2017,48(9):4623-4631

With this study, we aimed to assess the safety of using Curcuma longa in fish feed. Juvenile Astyanax aff. bimaculatus (0.83 ± 0.04 g) were kept in 24 80‐L aquaria, at a density of 0.5 fish L^?1 for 60 days. Six diets supplemented with 0.0, 20.0, 40.0, 60.0, 80.0 and 100.0 g kg^?1 were evaluated. Histopathological analysis of the gills showed that there was an increasing linear effect of turmeric on the frequency of lamellar aneurysm, hypertrophy of mucous cells, oedema and necrosis. There was a quadratic effect of turmeric supplementation on the frequency of fusion and disruption of secondary lamellae, vacuolation and hypertrophy of the epithelial cells, and the estimated values to minimize these variables were 4.63, 25.93 and 24.46 g kg^?1 respectively. There was a quadratic effect of turmeric on the gills index (I_BRA), and the estimated value to minimize this index was 30.23 g kg^?1. No effect of turmeric on the frequency of histopathological changes and organ index in fish liver was observed. Thus, we conclude that turmeric is not hepatotoxic for A. aff. bimaculatus; however, its use is safe at concentrations up to 30.23 g kg^?1 diet as a function of its gill toxic effect at higher doses.  相似文献   

Digestive enzyme spectra in crustacean decapods (Paleomonidae, Portunidae and Penaeidae) feeding in the natural habitat     

Maria Santos Reis Bonorino Figueiredo  & Alex J Anderson 《Aquaculture Research》2009,40(3):282-291

This work describes the profile of five proteases and four carbohydrases from the crustacean decapods Macrobrachium australiense (Holthuis), Scylla serrata (Forskal), Portunus pelagicus (Linnaeus), Penaeus esculentus, Penaeus plebejus (Hess) and Metapenaeus bennettae (Racck & Dall), feeding in the natural habitat, in order to provide an indication of their digestive capabilities. The results raised the following points. First, species from each family showed a particular suite of digestive enzymes. Second, the activity of cellulase from M. australiensis and S. serrata , using AZCL-HE cellulose as the substrate, was around 90% higher than that observed with AZO-CM cellulose. However, for P. pelagicus and P. esculentus , the enzyme activity was better with AZO-CM cellulose. Third, M. australiense displayed the highest ratio of amylase to protease activity. In contrast, Portunidae specie s, P. pelagicus and S. serrata showed the lowest ratios. Fourth, comparison of the laminarinase activity of M. bennettae and P. esculentus in October (Spring) and December (early Summer) showed a significant decrease in December. Finally, the wide distribution of digestive enzymes in these crustaceans may reflect different feeding habits and habitats.  相似文献   

Effects of hydrochar application on the dynamics of soluble nitrogen in soils and on plant availability          下载免费PDF全文

Inge Bargmann  Matthias C. Rillig  Andrea Kruse  Jörg‐Michael Greef  Martin Kücke 《植物养料与土壤学杂志》2014,177(1):48-58

Before hydrochars can be applied as soil amendments in agriculture, information about how hydrochar application affects soil nutrient cycles and plant growth are necessary. In this study, incubation experiments were performed to investigate hydrochar effects on N concentrations (NO$ _3^- $ , NH$ _4^+ $ ) in soils with different N pools (soil N, fertilizer N). A set of pot trials with three crop species (barley, phaseolus bean, leek) was conducted to determine hydrochar effects on plant N availability and biomass production after mineral‐N fertilization. Results of the incubation experiments show that hydrochar reduced the concentration of mineral N in soil within the first week after incorporation, especially that of nitrate. This was particularly evident, when hydrochars with high C : N ratio, high DOC and low mineral‐N contents were applied. Hydrochars promoted biomass production of barley and phaseolus bean in pot trials, which can be partly attributed to an increase in soil pH after hydrochar incorporation. Dry‐matter yield of leek tended to decrease after hydrochar application. Hydrochars with high C : N ratio decreased the plant's N content, an effect that was strongest with increased hydrochar concentration. Hydrochars with low C : N ratio did not affect the crop's N uptake. Our results show that the use of hydrochars as amendment in arable field or horticultural pot production will require an adjustment of N‐mineral‐fertilization strategies.  相似文献   

Unanticipated departures from breeding designs can be detected using microsatellite DNA parentage analyses     

Andrew K. Gray  John J. Joyce  Alex C. Wertheimer 《Aquaculture (Amsterdam, Netherlands)》2008,280(1-4):71-75

Using microsatellite analysis, a partial pedigree was constructed from an experiment designed to evaluate differences between hatchery Chinook salmon (Oncorhynchus tshawytscha) and their wild donor stocks. First generation (F₁) progeny were created by crossing both hatchery and wild females with hatchery and wild males to create hybrid and control lines. The pedigree analysis revealed an accidental switch of a half-sib control and hybrid F₁ family, which most likely occurred during incubation and led to the misclassification of individuals in those families. The experimental error propagated into the F₂ lines. The pedigree also revealed a number of unintended full-sib matings in the F₂ crosses. This resulted from the small numbers (5 females, 14 males) of wild fish available for the experiment and differential family survival of the F₁ fish. Because researchers used group-specific physical marks to track typed crosses and not family groups, and because physical marks cannot detect inadvertent movement of fish until they are large enough to mark, experimental error occurred that would have influenced the results had a DNA-based analysis not been employed to verify the integrity of the experiment.  相似文献   

Control of larval development by chemosensory neurons in Caenorhabditis elegans   总被引：12，自引：0，他引：12  

C I Bargmann  H R Horvitz 《Science (New York, N.Y.)》1991,251(4998):1243-1246

Larval development of the nematode Caenorhabditis elegans is controlled by the activities of four classes of chemosensory neurons. The choice between normal development and development into a specialized larval form called a dauer larva is regulated by competing environmental stimuli: food and a dauer pheromone. When the neuron classes ADF, ASG, ASI, and ASJ are killed, animals develop as dauer larvae regardless of environmental conditions. These neurons might sense food or dauer pheromone, or both, to initiate the specialized differentiation of many cell types that occurs during dauer formation. Entry into and exit from the dauer stage are primarily controlled by different chemosensory neurons. The analysis of mutants defective in dauer formation indicates that the chemosensory neurons are active in the absence of sensory inputs and that dauer pheromone inhibits the ability of these neurons to generate a signal necessary for normal development.  相似文献   

Assessing the benefits of the marine protected area of Punta Coles,southern Peru (south-east Pacific) on productivity of conspicuous benthic species using pre-image population analysis     

Alex Tejada  Danny Baldarrago  Ruslan Pastor  Marco Ortiz 《水产资源保护:海洋与淡水生态系统》2023,33(1):29-43

1. The coastal marine protected ecosystem at Punta Coles (as a part of the Reserva Nacional de Islas, Islotes y Puntas Guaneras) is located in a highly exploited area in southern Peru and contains several commercial, bioengineering and other benthic species.
2. Pre-image population analysis was used to estimate the transient values of intrinsic growth rate (r) based on biomass and density time series as a proxy of productivity to assess the effectiveness of protection.
3. The outcomes obtained showed that the gastropods Concholepas concholepas, Fissurella latimartiginata and the tunicate Purya chilensis showed a reduction of productivity during recent years, whilst the sea urchin Loxechinus albus, the barnacle Balanus laevis and the bivalve Semimytilus algosus showed an opposite pattern. Several species exhibited a chaotic dynamic, coinciding with the highest productivity values. In 2016 and 2017, several species exhibited a reduction of their abundance which could be delayed responses explained by changes in oceanographic conditions (reduction of coastal upwelling), La Niña event and illegal harvest.
4. The above notwithstanding, the results suggest that effective protection of benthic species in the protected ecosystem of Punta Coles have been partially accomplished. Therefore, this work could be considered a baseline study, permitting the subsequent monitoring of productivity of the main species inhabiting the coastal area of Punta Coles.
5. Pre-image population analysis could be used as a complimentary analytical tool since it enables the evaluation of transient population parameters (e.g. productivity) thus aiding population management, conservation and monitoring decisions.

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