دانلود و نمایش مقالات مرتبط با Dispersal::صفحه 1
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نتیجه جستجو - Dispersal

تعداد مقالات یافته شده: 5
ردیف عنوان نوع
1 Life history, uses, trade and management of Diospyros crassiflora Hiern, the ebony tree of the Central African forests: A state of knowledge
تاریخچه زندگی، استفاده، تجارت و مدیریت Diospyros crassiflora Hiern، درخت آبنوس جنگل های آفریقای مرکزی: وضعیت دانش-2021
The Central African forest ebony, Diospyros crassiflora Hiern, is a small tree native to the moist forests of the Congo Basin. Its appealing black heartwood was one of the first products to be exported from the Gulf of Guinea in the 17th century and is today one of the main sources of ebony globally. Like for other ebony species, its commercial exploitation raises serious questions about the long-term sustainability of its trade and the viability of its populations, but the dots are yet to be joined. An examination of the interface between biology, trade, and ecology is crucial to identify the interrelated factors that could influence the potential success of its conservation. This paper reviews scientific and grey literature, forest inventories, herbarium and trade data to provide a critical assessment of the main threats to D. crassiflora populations and gaps in the current state of knowledge. It is shown here that the species is widespread but never abundant. In the longer term the species is threatened by forest conversion to agriculture and widespread hunting of large mammals on which the species rely for seed dispersal. It is currently selectively logged principally to make musical instruments and for the hongmu Chinese market, for which only one alternative black wood, the near-threatened Dalbergia melanoxylon Guill. et Perr., is commercially available. Trade statistics suggest that exports from source countries where the species is cut under the forest concession system are relatively low compared to countries like Cameroon which has seen a recent increase in exports, and where ebony is exploited without forest management plans. Logging remains a concern where the exploitation and trade of D. crassiflora are managed in response to demand rather than informed by current stock levels, growth rate and the particular reproductive biology of this species. The recent successes of private sector initiatives to ensure the long-term supply of ebony in Cameroon are promising, but would require long-term and large-scale commitments involving direct and indirect stakeholders to develop programs for the plantation and policies for the sustainable management of the species.
keywords: آبنوس | شکار | جنگل زدایی | تجارت | جنگل مرطوب آفریقا | گیتار | Ebony | Hunting | Deforestation | Trade | African moist forest | Guitar | CITES
مقاله انگلیسی
2 Preserving data security in distributed fog computing
حفظ امنیت داده ها در محاسبات مه آلود-2019
In this paper, a novel cryptographic solution is proposed to secure data in fog computing. The so- lution combines the AES-GMAC operation mode with information dispersal over GF(2 w ) to provide data confidentiality, integrity, and availability along with source authentication. The value of w is flexible (8, 16, 32 or 64) and it could be configured according to the fog device features. More- over, the proposed cryptographic solution is based on the dynamic key-dependent approach, which allows for a good compromise between the security level and computational complexity. In the pro- posed solution, the collected data at one fog node is encrypted, authenticated and dispersed in a pseudo-random manner to its n neighbor fog nodes. For data recovery, any k of the n frag- ments along with the corresponding dynamic key are required to retrieve the original data. This complicates the attackers task who needs to compromise at least k fog nodes to disclose the encrypted data. Additionally, attackers should seek the dynamic key, which is different for each input data. On the other hand, redundant fragments protect the stored data against up to ( n −k ) fog nodes’ failure or un- availability. The security and performance analysis tests show that the proposed security scheme exhibits a high level of efficiency and robustness
مقاله انگلیسی
3 Anthropogenic Marine Debris assessment with Unmanned Aerial Vehicle imagery and deep learning: A case study along the beaches of the Republic of Maldives
ارزیابی بقایای دریایی آنتروپوژنیک با تصاویر بدون سرنشین هوایی و یادگیری عمیق: مطالعه موردی در سواحل جمهوری مالدیو-2019
Anthropogenic Marine Debris (AMD) is one of the major environmental issues of our planet to date, and plastic accounts for 80% of total AMD. Beaches represent one of themainmarine compartmentwhere AMD accumulates, but few and scattered regional assessments are available from literature reporting quantitative estimation of AMD distributed on the shorelines. However, accessing information on the AMD accumulation rate on beaches, and the associated spatiotemporal oscillations, would be crucial to refining global estimation on the dispersal mechanisms. In our work, we address this issue by proposing an ad-hocmethodology formonitoring and automatically quantifying AMD, based on the combined use of a commercial Unmanned Aerial Vehicle (UAV) (equipped with an RGB high-resolution camera) and a deep-learning based software (i.e.: PlasticFinder). Remote areas were monitored by UAV and were inspected by operators on the ground to check and to categorise all AMD dispersed on the beach. The high-resolution images obtained from UAV allowed to visually detect a percentage of the objects on the shores higher than 87.8%, thus providing suitable images to populate training and testing datasets, aswell as gold standards to evaluate the software performance. PlasticFinder reached a Sensitivity of 67%,with a Positive Predictive Value of 94%, in the automatic detection of AMD, but a limitation was found, due to reduced sunlightconditions, thus restricting to the use of the software in its present version. We, therefore, confirmed the efficiency of commercial UAVs as tools for AMD monitoring and demonstrated - for the first time - the potential of deep learning for the automatic detection and quantification of AMD.
Keywords: Anthropogenic Marine-Debris | Unmanned Aerial Vehicles | Machine learning | Deep learning algorithms | Maldives | Beach
مقاله انگلیسی
4 Criminalising protest through the expansion of police ‘move-on’ powers: A case study from Australia
جرم انگاری اعتراض از طریق گسترش قدرت تحرک پلیس: مطالعه موردی استرالیا-2019
This article analyses the evolution of police ‘move-on’ (dispersal) powers in Australia, with a focus on how this form of statutory police power is being recalibrated as a technique for deterring and closing down public place protests. Using a case study from recent events in the state of New South Wales, we draw attention to the ways in which governments have begun to employ the move-on power as a tool for imposing their own visions of how public places should be used and how protests are allowed to be conducted. We highlight the work done by the ambiguous and malleable concept of ‘public safety’ and the imperative of not permitting protests to interrupt business activities. We argue that the combined effect of the ascendancy of these preferences, and the pre-emptive logic which is at the heart of move-on powers, is to produce a serious challenge to the vision of public places as sites for dissent and democratic mobilisation.
Keywords: Criminalisation | Police powers | Dispersal | Protest | Public order | Australia
مقاله انگلیسی
5 The use of social network analysis to examine the transmission of Salmonella spp: within a vertically integrated broiler enterprise
استفاده از تجزیه و تحلیل شبکه های اجتماعی برای بررسی انتقال سالمونلا spp: در یک شرکت گوشتی یکپارچه عمودی-2017
To better understand factors influencing infectious agent dispersal within a livestock population infor mation is needed on the nature and frequency of contacts between farm enterprises. This study uses social network analysis to describe the contact network within a vertically integrated broiler poultry enterprise to identify the potential horizontal and vertical transmission pathways for Salmonella spp. Nodes (farms, sheds, production facilities) were identified and the daily movement of commodities (eggs, birds, feed, litter) and people between nodes were extracted from routinely kept farm records. Three time periods were examined in detail, 1- and 8- and 17-weeks of the production cycle and contact networks were described for all movements, and by commodity and production type. All nodes were linked by at least one movement during the study period but network density was low indicating that all potential pathways between nodes did not exist. Salmonella spp. transmission via vertical or horizontal pathways can only occur along directed pathways when those pathways are present. Only two locations (breeder or feed nodes) were identified where the transmission of a single Salmonella spp. clone could theoretically percolate through the network to the broiler or processing nodes. Only the feed trans mission pathway directly connected all parts of the network.
Keywords: Salmonella | Poultry | Social network analysis | Broiler |Chicken
مقاله انگلیسی
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