859 resultados para cost and benefit


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Arm/Rmt methyltransferases have emerged recently in pathogenic bacteria as enzymes that confer high-level resistance to 4,6-disubstituted aminoglycosides through methylation of the G1405 residue in the 16S rRNA (like ArmA and RmtA to -E). In prokaryotes, nucleotide methylations are the most common type of rRNA modification, and they are introduced posttranscriptionally by a variety of site-specific housekeeping enzymes to optimize ribosomal function. Here we show that while the aminoglycoside resistance methyltransferase RmtC methylates G1405, it impedes methylation of the housekeeping methyltransferase RsmF at position C1407, a nucleotide that, like G1405, forms part of the aminoglycoside binding pocket of the 16S rRNA. To understand the origin and consequences of this phenomenon, we constructed a series of in-frame knockout and knock-in mutants of Escherichia coli, corresponding to the genotypes rsmF(+), ΔrsmF, rsmF(+) rmtC(+), and ΔrsmF rmtC(+). When analyzed for the antimicrobial resistance pattern, the ΔrsmF bacteria had a decreased susceptibility to aminoglycosides, including 4,6- and 4,5-deoxystreptamine aminoglycosides, showing that the housekeeping methylation at C1407 is involved in intrinsic aminoglycoside susceptibility in E. coli. Competition experiments between the isogenic E. coli strains showed that, contrary to expectation, acquisition of rmtC does not entail a fitness cost for the bacterium. Finally, matrix-assisted laser desorption ionization (MALDI) mass spectrometry allowed us to determine that RmtC methylates the G1405 residue not only in presence but also in the absence of aminoglycoside antibiotics. Thus, the coupling between housekeeping and acquired methyltransferases subverts the methylation architecture of the 16S rRNA but elicits Arm/Rmt methyltransferases to be selected and retained, posing an important threat to the usefulness of aminoglycosides worldwide.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Plasmid pB1000 is a mobilizable replicon bearing the bla(ROB-1) beta-lactamase gene that we have recently described in Haemophilus parasuis and Pasteurella multocida animal isolates. Here we report the presence of pB1000 and a derivative plasmid, pB1000', in four Haemophilus influenzae clinical isolates of human origin. Pulsed-field gel electrophoresis showed unrelated patterns in all strains, indicating that the existence of pB1000 in H. influenzae isolates is not the consequence of clonal dissemination. The replicon can be transferred both by transformation and by conjugation into H. influenzae, giving rise to recipients resistant to ampicillin and cefaclor (MICs, > or =64 microg/ml). Stability experiments showed that pB1000 is stable in H. influenzae without antimicrobial pressure for at least 60 generations. Competition experiments between isogenic H. influenzae strains with and without pB1000 revealed a competitive disadvantage of 9% per 10 generations for the transformant versus the recipient. The complete nucleotide sequences of nine pB1000 plasmids from human and animal isolates, as well as the epidemiological data, suggest that animal isolates belonging to the Pasteurellaceae act as an antimicrobial resistance reservoir for H. influenzae. Further, since P. multocida is the only member of this family that can colonize both humans and animals, we propose that P. multocida is the vehicle for the transport of pB1000 between animal- and human-adapted members of the Pasteurellaceae.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Traditional knowledge associated with genetic resources (TKaGRs) is acknowledged as a valuable resource. Its value draws from economic, social, cultural, and innovative uses. This value places TK at the heart of competing interests as between indigenous peoples who hold it and depend on it for their survival, and profitable industries which seek to exploit it in the global market space. The latter group seek, inter alia, to advance and maintain their global competitiveness by exploiting TKaGRs leads in their research and development activities connected with modern innovation. Biopiracy remains an issue of central concern to the developing world and has emerged in this context as a label for the inequity arising from the misappropriation of TKaGRs located in the South by commercial interests usually located in the North. Significant attention and resources are being channeled at global efforts to design and implement effective protection mechanisms for TKaGRs against the incidence of biopiracy. The emergence and recent entry into force of the Nagoya Protocol offers the latest example of a concluded multilateral effort in this regard. The Nagoya Protocol, adopted on the platform of the Convention on Biological Diversity (CBD), establishes an open-ended international access and benefit sharing (ABS) regime which is comprised of the Protocol as well as several complementary instruments. By focusing on the trans-regime nature of biopiracy, this thesis argues that the intellectual property (IP) system forms a central part of the problem of biopiracy, and so too to the very efforts to implement solutions, including through the Nagoya Protocol. The ongoing related work within the World Intellectual Property Organization (WIPO), aimed at developing an international instrument (or a series of instruments) to address the effective protection of TK, constitutes an essential complementary process to the Nagoya Protocol, and, as such, forms a fundamental element within the Nagoya Protocol’s evolving ABS regime-complex. By adopting a third world approach to international law, this thesis draws central significance from its reconceptualization of biopiracy as a trans-regime concept. By construing the instrument(s) being negotiated within WIPO as forming a central component part of the Nagoya Protocol, this dissertation’s analysis highlights the importance of third world efforts to secure an IP-based reinforcement to the Protocol for the effective eradication of biopiracy.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

保护区是否真的能起保护作用?保护区究竟如何布局?这是自然保护区的建设一直争论不休的课题。就大熊猫保护而言,目前面临的最紧迫问题可能不是保护区数量多少的问题,而是这些多个保护区组成的保护区群的配置或格局是否合理。因此,本研究以岷山大熊猫保护区群为研究对象,分析现有大熊猫及栖息地及其保护现状,指出目前保护区存在的问题,并对岷山大熊猫自然保护区群合理布局提出建议性设计,以期为大熊猫保护及自然保护区建设的理论提供借鉴。 到目前,为了保护大熊猫,在岷山地区已经建立了1 7个自然保护区,这些保护区的建立对大熊猫的保护起到了非常重要的重要。但是,大熊猫栖息地仍然持续下降。就其原因有两方面,即岷山地区人为活动的干扰,如旅游业的盲目发展。但,同时大熊猫自然保护区本身的布局存在一定的不合理性。最后,从景观尺度上提出岷山大熊猫保护区群合理建设的布局,即在分析现有保护布局基础上,找到优先保护的敏感地带建立廊道,将所有保护区连成布局合理的保护区群。 大熊猫受威胁的关键因子并不是竹子,而是森林.竹子复合系统的破碎化或质量的退化,故保护大熊猫应从保护森林、恢复森林.竹子复合生态系统的质量入手。但是,具体实践中究竞采取什么模式来恢复退化的大熊猫栖息地?选取不同模式的科学依据是什么?如何评判不同恢复模式的成本和效益?这些方面的工作到目前缺少系统研究。本研究在分析了岷山地区自然、社会与经济条件的基础上,从荒山荒地造林、天然林保护与低效林地改造主要植被恢复措施着手,全面分析各类植被恢复措施所形成植被的生态效益(保持水土、涵养水源、保持肥力等)、经济收益(木材、果品和林副特产品)、社会效益(种植结构、劳动力再分配等),总结出植被恢复成本和效益的构成要素,计算主要植被恢复模式的成本和效益,为选择适宜的植被恢复措施、典型植被恢复模式和合理确定植被恢复技术提供科学依据,从而推动岷山植被快速健康地恢复,为大熊猫提供适宜的生存空间。 三峡大坝的建设使其固有水域的人为改造导致水位上升,使原本连续的山地生态系统被分割成大小不等的岛屿。水位变化导致的这种生境岛屿化为栖息地破碎化和岛屿生物地理学提供了十分难得的实证研究的机会。然而,同时,这种栖息地的片段化无疑对三峡库区生物多样性保护和生态系统的完整性造成威胁。到目前,为了监测库区建设对生态环境的影响,已经建立了22个定位观测站,但没有一个是生境破碎化方面的,为此建议尽快建立生境破碎化方面的定位研究站。三峡库区生物多样性丰富,但保护区面积仅仅占库区面积的6.9%,而同期我国已经建立了1 999个自然保护区,占国土面积的15%,因此,非常迫切建立更多的保护区(至少达到全国平均水平)。为了从宏观尺度上加强对库区的综合保护,建议从景观生态学的角度出发,将库区作为一个自然、社会和经济复合生态系绕对待。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Social Networking explained by an economic model of cost and benefit.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

O presente trabalho pretende demonstrar que o real avanço com o advento da previsão legal da empresa individual de responsabilidade limitada – EIRELI é a proteção conferida pela autonomia patrimonial e não a limitação da responsabilidade do comerciante. Visto que há uma escassez na literatura nacional a respeito do tema, iremos utilizar bibliografia norte americana como base para a primeira parte da pesquisa. Assim poderemos identificar as vantagens e desvantagens da responsabilidade limitada e da autonomia patrimonial para podermos concluir com uma análise de custo e benefício destes institutos jurídicos. Por fim, utilizaremos do conhecimento adquirido por toda esta análise para aplicarmos e adaptarmos as especificações da EIRELI. Nos apoiaremos em doutrina nacional somente em relação as regras de sociedades limitadas, pois a lei determina que estas serão usadas supletivamente para as empresas individuais de responsabilidade limitada. Com base nisso o trabalho será finalizado com uma questão pouco explorada, que é em relação a penhora e liquidação das quotas na EIRELI.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Despite the general belief that the interaction between extrafloral nectaries (EFNs) and ants is mutualistic, the defensive function of EFNs has been poorly documented in South American savannas. In this article, we evaluate the potential impact of EFNs (benefits and costs) on two species of plants from the dry areas of Central Brazil, Anemopaegma album and Anemopaegma scabriusculum (Bignoniaceae). In particular, we characterize the composition of substances secreted by the EFNs, test whether EFNs attract ants, and whether ants actually present a defensive role, leading to reduced herbivory and increased plant fitness. Histochemical analyses indicated that EFNs from both species of Anemopaegma secrete an exudate that is composed of sugars, and potentially lipids and proteins. Furthermore, EFNs from both species were shown to present a significant role in ant attraction. However, contrary to common expectations, ants were not found to protect plants against herbivore attack. No effect was found between ant visitation and flower or fruit production in A. album, while the presence of ants led to a significant decrease in flower production in A. scabriusculum. These results suggest that EFNs might present a similar cost and benefit in A. album, and a higher cost than benefit in A. scabriusculum. Since the ancestor of Anemopaegma occupied humid forests and already presented EFNs that were maintained in subsequent lineages that occupied savannas, we suggest that phylogenetic inertia might explain the presence of EFNs in the species of Anemopaegma in which EFNs lack a defensive function.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Infrastructure management agencies are facing multiple challenges, including aging infrastructure, reduction in capacity of existing infrastructure, and availability of limited funds. Therefore, decision makers are required to think innovatively and develop inventive ways of using available funds. Maintenance investment decisions are generally made based on physical condition only. It is important to understand that spending money on public infrastructure is synonymous with spending money on people themselves. This also requires consideration of decision parameters, in addition to physical condition, such as strategic importance, socioeconomic contribution and infrastructure utilization. Consideration of multiple decision parameters for infrastructure maintenance investments can be beneficial in case of limited funding. Given this motivation, this dissertation presents a prototype decision support framework to evaluate trade-off, among competing infrastructures, that are candidates for infrastructure maintenance, repair and rehabilitation investments. Decision parameters' performances measured through various factors are combined to determine the integrated state of an infrastructure using Multi-Attribute Utility Theory (MAUT). The integrated state, cost and benefit estimates of probable maintenance actions are utilized alongside expert opinion to develop transition probability and reward matrices for each probable maintenance action for a particular candidate infrastructure. These matrices are then used as an input to the Markov Decision Process (MDP) for the finite-stage dynamic programming model to perform project (candidate)-level analysis to determine optimized maintenance strategies based on reward maximization. The outcomes of project (candidate)-level analysis are then utilized to perform network-level analysis taking the portfolio management approach to determine a suitable portfolio under budgetary constraints. The major decision support outcomes of the prototype framework include performance trend curves, decision logic maps, and a network-level maintenance investment plan for the upcoming years. The framework has been implemented with a set of bridges considered as a network with the assistance of the Pima County DOT, AZ. It is expected that the concept of this prototype framework can help infrastructure management agencies better manage their available funds for maintenance.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Dissertação de mest. em Ciências Económicas e Empresariais, Unidade de Ciências Económicas e Empresariais, Univ. do Algarve, 1995

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper discusses major obstacles for the adoption of low cost level crossing warning devices (LCLCWDs) in Australia and reviews those trialed in Australia and internationally. The argument for the use of LCLCWDs is that for a given investment, more passive level crossings can be treated, therefore increasing safety benefits across the rail network. This approach, in theory, reduces risk across the network by utilizing a combination of low-cost and conventional level crossing interventions, similar to what is done in the road environment. This paper concludes that in order to determine if this approach can produce better safety outcomes than the current approach, involving the incremental upgrade of level crossings with conventional interventions, it is necessary to perform rigorous risk assessments and cost-benefit analyses of LCLCWDs. Further research is also needed to determine how best to differentiate less reliable LCCLWDs from conventional warning devices through the use of different warning signs and signals. This paper presents a strategy for progressing research and development of LCLCWDs and details how the Cooperative Research Centre (CRC) for Rail Innovation is fulfilling this strategy through the current and future affordable level crossing projects.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Traffic safety in rural highways can be considered as a constant source of concern in many countries. Nowadays, transportation professionals widely use Intelligent Transportation Systems (ITS) to address safety issues. However, compared to metropolitan applications, the rural highway (non-urban) ITS applications are still not well defined. This paper provides a comprehensive review on the existing ITS safety solutions for rural highways. This research is mainly focused on the infrastructure-based control and surveillance ITS technology, such as Crash Prevention and Safety, Road Weather Management and other applications, that is directly related to the reduction of frequency and severity of accidents. The main outcome of this research is the development of a ‘ITS control and surveillance device locating model’ to achieve the maximum safety benefit for rural highways. Using cost and benefits databases of ITS, an integer linear programming method is utilized as an optimization technique to choose the most suitable set of ITS devices. Finally, computational analysis is performed on an existing highway in Iran, to validate the effectiveness of the proposed locating model.