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181.
There are many factors that determine what forestry activities forest owners carry out in their forest properties and that influence whether forest owners engage in entrepreneurial activity. This paper explores whether the values and objectives of forest owners influence their forestry behaviour and their engagement in entrepreneurial activity. This is done through a review of the literature on private forest owners’ typologies based on owners’ objectives. The review reveals that typologies typically divide forest owners into two main groups. The primary objective of the first group of owners is production (of wood and non-wood goods and services) usually, although not exclusively, so as to generate economic activity. The primary objective of the second group is consumption (of wood and non-wood goods and services). There is a tacit assumption in the studies reviewed that goals and objectives do influence forestry behaviour but few studies have actually assessed whether this is the case. The general finding is that forest owners whose objectives are timber production and who are business-oriented are more likely to manage and harvest their stands. No research focusing on the link between owners’ objective and wider entrepreneurial activity in forests was found.  相似文献   
182.
Some legume species of the Crotalaria genus are specifically nodulated by methylotrophic bacteria belonging to the Methylobacterium nodulans species. The feature of this symbiotic bacterium is its ability to oxidize methanol, a property based on the presence of a methanol dehydrogenase enzyme. Despite a good knowledge of this property and its implication in symbiosis, the molecular dialogue between M. nodulans and crotalaria podocarpa leading to symbiosis is largely unknown, except the presence of a nodA nodulation gene in the genome of M. nodulans ORS 2060. To investigate if M. nodulans ORS 2060 produces Nod factors, molecules considered as the major bacteria-to-plant signals essential for the establishment of rhizobia–legume symbiosis, we identified and sequenced a nodDABCUIJHQ cluster from a genomic library of ORS 2060. Phylogenetic analyses of nod genes revealed that M. nodulans ORS 2060 form a branch together with Burkholderia tuberum STM678 and a strain of Methylobacterium sp. (4-46) isolated from Lotononis, and distinct from all the other rhizobia. To analyse the regulation of ORS 2060 nod genes, we constructed a nodA–LacZ promoter fusion to monitor the nod gene expression with various flavonoids. The flavone apigenin was found to be the strongest inducer of nod gene expression in M. nodulans ORS 2060. This latter flavonoid was used to induce ORS 2060, and Nod factors were purified by high-performance liquid chromatography (HPLC) and further characterized by mass spectrometry. One major Nod factor structure was identified as a pentamer of chitin substituted by C18:1 or C16:0 acyl chains on the non-reducing end and 6-O-sulphated on the other end, suggesting a classic symbiotic dialogue between M. nodulans and C. podocarpa.  相似文献   
183.
Purpose: Plant-derived essential oils and their encapsulations have recently received increasing interest as an alternative to synthetic biopesticides suitable for integrated pest management and organic farming. In this study, combinations of essential oils (EO) from Rosmarinus officinalis with Cymbopogon citratus and Pelargonium graveolens with Thymus vulgaris in two formulations including encapsulate were tested for their potential for wheat protection against adults and larvae of Oulema melanopus (L.).

Materials and methods: The chemical composition of the essential oils was analyzed by gas chromatography-mass spectrometry (GC-MS). Testing of insecticidal activity of the evaluated substances was conducted with 2.5?ml of tested combinations of EOs sprayed on the paper. Ten adults or larvae of O. melanopus were placed into a vessel. Control of mortality of O. melanopus specimens was assessed after 24?h after establishment of the experiment.

Results and conclusions: Tarsal contact toxicity assay showed the effectiveness of EO in concentration against O. melanopus larvae and adults in both formulations (essential oil and encapsulation) causing 100% mortality within 24?h. These results indicate the great potential of these essential oils and their encapsulations for future use in crop protection against insect pests.  相似文献   
184.
185.
Sustainable soil management requires reliable and accurate monitoring of changes in soil organic matter (SOM). However, despite the development of improved analytical techniques during the last decades, there are still limits in the detection of small changes in soil organic carbon content and SOM composition. This study focused on the detection of such changes under laboratory conditions by adding different organic amendments to soils. The model experiments consisted of artificially mixing soil samples from non‐fertilized plots of three German long‐term agricultural experiments in Bad Lauchstädt (silty loam), Grossbeeren (silty sand), and Müncheberg (loamy sand) with straw, farmyard manure, sheep faeces, and charcoal in quantities from 3 to 180 t ha?1 each. In these mixtures we determined the organic carbon contents by elemental analysis and by thermal mass losses (TML) determined by thermogravimetry. The results confirmed the higher reliability of elemental analysis compared to TML for organic carbon content determination. The sensitivity of both methods was not sufficient to detect the changes in organic carbon content caused by small quantities of organic amendments (3 t ha?1 or 0.1–0.4 g C kg?1 soil). In the case of elemental analysis, the detectability of changes in carbon content increased with quantities of added amendments, but the method could not distinguish different types of organic amendments. On the contrary, the based on analysis of degradation temperatures, the TML allowed this discrimination together with their quantitative analysis. For example, added charcoal was not visible in TML from 320 to 330°C, which is used for carbon content determination. However, increasing quantities of charcoal were reflected in a higher TML around 520°C. Furthermore, differences between measured (with TML110–550) and predicted mass loss on ignition using both organic carbon (with TML330) and clay contents (with TML140) were confirmed as a suitable indicator for detection of organic amendments in different types of soils. We conclude that thermogravimetry enables the sensitive detection of organic fertilizers and organic amendments in soils under arable land use.  相似文献   
186.
Several lectins have been found in crustaceans, and it has been suggested that they play roles in cell signalling, cell–cell interaction, protein synthesis and pathogen recognition. These functions are performed through their specificity for carbohydrates. This review analyses the carbohydrate specificity, tissue distribution and participation in the immune responses of lectins in crustaceans. Furthermore, we explore some data showing that lectin expression seems to be stimulated by pathogens, favouring crustacean survival.  相似文献   
187.
In recent years, policy‐makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non‐target species that are unknowingly released alongside intentionally‐introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan‐continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits.  相似文献   
188.
Canine meningiomas are currently graded using the human grading system. Recently published guidelines have adapted the human grading system for use in dogs. The goal of this study was to validate the new guidelines for canine meningiomas. To evaluate the inter-observer agreement, 5 veterinary surgical pathologists graded 158 canine meningiomas following the human grading system alone or with the new guidelines. The inter-observer agreement for histologic grade and each of the grading criteria (mitotic grade, invasion, spontaneous necrosis, macronucleoli, small cells, hypercellularity, pattern loss and anaplasia) was evaluated using the Fleiss kappa index. The diagnostic accuracy (sensitivity and specificity) was assessed by comparing the diagnoses obtained with the 2 grading systems with a consensus grade (considered the reference classification). The consensus histologic grade was obtained by agreement between 4 experienced veterinary neuropathologists following the guidelines. Compared with the human grading alone, the canine-specific guidelines increased the inter-observer agreement for: histologic grade (κ = 0.52); invasion (κ = 0.67); necrosis (κ = 0.62); small cells (κ = 0.36); pattern loss (κ = 0.49) and anaplasia (κ = 0.55). Mitotic grade agreement remained substantial (κ = 0.63). The guidelines improved the sensitivity in identifying grade 1 (95.6%) and the specificity in identifying grade 2 (96.2%) meningiomas. In conclusion, the new grading guidelines for canine meningiomas are associated with an overall improvement in the inter-observer agreement and higher diagnostic accuracy in diagnosing grade 1 and grade 2 meningiomas.  相似文献   
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