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Multivesicular Bodies in Neurons: Distribution, Protein Content, and Trafficking Functions

VON BARTHELD, CHRISTOPHER S.; ALTICK, AMY L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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35.64%
Multivesicular bodies (MVBs) are intracellular endosomal organelles characterized by multiple internal vesicles that are enclosed within a single outer membrane. MVBs were initially regarded as purely prelysosomal structures along the degradative endosomal pathway of internalized proteins. MVBs are now known to be involved in numerous endocytic and trafficking functions, including protein sorting, recycling, transport, storage, and release. This review of neuronal MVBs summarizes their research history, morphology, distribution, accumulation of cargo and constitutive proteins, transport, and theories of functions of MVBs in neurons and glia. Due to their complex morphologies, neurons have expanded trafficking and signaling needs, beyond those of “geometrically simpler” cells, but it is not known whether neuronal MVBs perform additional transport and signaling functions. This review examines the concept of compartment-specific MVB functions in endosomal protein trafficking and signaling within synapses, axons, dendrites and cell bodies. We critically evaluate reports of the accumulation of neuronal MVBs based on evidence of stress-induced MVB formation. Furthermore, we discuss potential functions of neuronal and glial MVBs in development...

Hindered submicron mobility and long-term storage of presynaptic dense-core granules revealed by single-particle tracking

Scalettar, B. A.; Jacobs, C.; Fulwiler, A.; Prahl, L.; Simon, A.; Hilken, L.; Lochner, J. E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
25.8%
Dense-core granules (DCGs) are organelles found in neuroendocrine cells and neurons that house, transport, and release a number of important peptides and proteins. In neurons, DCG cargo can include the secreted neuromodulatory proteins tissue plasminogen activator (tPA) and/or brain-derived neurotrophic factor (BDNF), which play a key role in modulating synaptic efficacy in the hippocampus. This function has spurred interest in DCGs that localize to synaptic contacts between hippocampal neurons, and several studies recently have established that DCGs localize to, and undergo regulated exocytosis from, postsynaptic sites. To complement this work, we have studied presynaptically-localized DCGs in hippocampal neurons, which are much more poorly understood than their postsynaptic analogs. Moreover, to enhance relevance, we visualized DCGs via fluorescence labeling of exogenous and endogenous tPA and BDNF. Using single-particle tracking, we determined trajectories of more than 150 presynaptically-localized DCGs. These trajectories reveal that mobility of DCGs in presynaptic boutons is highly hindered and that storage is long-lived. We also computed mean-squared displacement curves, which can be used to elucidate mechanisms of transport. Over shorter time windows...

Regulation of membrane trafficking by signalling on endosomal and lysosomal membranes

Li, Xinran; Garrity, Abigail G; Xu, Haoxing
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.63%
Endosomal and lysosomal membrane trafficking requires the coordination of multiple signalling events to control cargo sorting and processing, and endosome maturation. The initiation and termination of signalling events in endosomes and lysosomes is not well understood, but several key regulators have been identified, which include small GTPases, phosphoinositides, and Ca2+. Small GTPases act as master regulators and molecular switches in a GTP-dependent manner, initiating signalling cascades to regulate the direction and specificity of endosomal trafficking. Phosphoinositides are membrane-bound lipids that indicate vesicular identities for recruiting specific cytoplasmic proteins to endosomal membranes, thus allowing specificity of membrane fusion, fission, and cargo sorting to occur within and between specific vesicle compartments. In addition, phosphoinositides regulate the function of membrane proteins such as ion channels and transporters in a compartment-specific manner to mediate transport and signalling. Finally, Ca2+, a locally acting second messenger released from intracellular ion channels, may provide precise spatiotemporal regulation of endosomal signalling and trafficking events. Small GTPase signalling can regulate phosphoinositide conversion during endosome maturation...

West Bank and Gaza : Palestinian Trade, West Bank Routes

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
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35.85%
The World Bank analyzed the logistics of trade corridors from Gaza through Egypt as an alternative to sending exports via Israel. This paper extends this work and examines the viability of different trade routes from the West Bank. Another earlier paper describes the complex agglomeration of physical obstacles, administrative barriers and permit policies that Israel uses to restrict movement in the West Bank. This paper also builds on this work by quantifying some of the resulting costs. West Bank enterprises have essentially two options to access the world market: (a) out through Israeli ports or airport; and (b) across the Jordan River and out through Jordan ports or airport. While, it is also possible to send goods across Israel and through Egypt, this route is currently uneconomical.

Why Cargo Dwell Time Matters in Trade

Raballand, Gael; Refas, Salim; Beuran, Monica; Isik, Gozde
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
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35.83%
The international community has been increasing investment in projects that promote trade facilitation and improve logistics in the developing world, including in ports. In Africa, a key motivation for such projects has been a presumption that poor infrastructure and inefficient border control agencies are the major causes of extended delays in sub-Saharan Africa (SSA) ports. Based on new data and analysis, this note argues that collusion between controlling agencies, port authorities, private terminal operators, logistics operators, and large shippers is an important part of the problem. Decreasing dwell times in ports requires governments to combat collusive practices between the private sector and public authorities and recognize that large-scale investments in infrastructure are not sufficient to reduce logistics delays.

Private Participation in Port Facilities : Recent Trends

Sommer, Dirk
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
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25.82%
The private sector has become increasingly involved in the operation of common-user port facilities during the 1990s, following public sector dominance of the sector since the 1940s. During the past decade the reform of port administration has gained momentum in industrial and developing countries alike. Between 1990 and 1998, 112 port projects with private participation reached financial closure in twenty-eight developing countries, with investment commitments totaling more than US$9 billion. Most projects are in East Asia and Latin America, and most are long-term concessions. This Note provides an overview of the emerging trends in developing countries and outlines the main issues for the future. These issues include sustaining competition at a regional level, across networks, and with other transport sectors, such as road and rail.

Trade and Logistics in East Asia : A Development Agenda

Carruthers, Robin; Bajpai, Jitendra N.; Hummels, David
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
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35.82%
This report is part of a strategy to promotes trade competitiveness within the East Asia and Pacific Region. It presents an overview of the logistics issues facing East Asia countries and proposes a development agenda for them. Based on the recognition that the countries have basic differences in their level of development, extent of openness, and composition of trade, it begins by discussing the benefits of improved logistics. The East Asian countries are organized into an action matrix, with an analysis of the logistics needs appropriate to each group. The country working papers (volumes 2, 3, & 5)discuss the assessment of preset logistics services and the impediments they impose upon, and opportunities they offer for, expanded trade, including policy reform proposals. The special report on ports (volume 4) addresses port development in relation to urban growth.

Cambodia Trade Corridor Performance Assessment

World Bank Group
Fonte: Phnom Penh Publicador: Phnom Penh
EN_US
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25.88%
The study found that logistics costs are high due to transshipment costs and various forms of payments. Many of these payments are imposed by the private sector with little or no transparency on how or where the costs are incurred. International trade corridors in Cambodia therefore perform well in terms of time but not cost. However, the corridors with transshipment have higher costs than the national corridor between Phnom Penh and Sihanoukville or the river corridor to the port of Cai Mep in Vietnam. Large shippers and international firms prefer to use several sub-contractors to make logistics arrangements so they do not have to coordinate what can be fairly complex and challenging arrangements for shipments. Intermediation in logistics is largely carried out by local agencies, leading to high intermediation costs. The main reason for the high intermediation cost is the prevalence and wide acceptance of facilitation fees as inducements for fast clearance and processing. Facilitation fees, largely informal...

Understanding the Operations of Freight Forwarders

Mendoza Alcantara, Alejandra; Fernandes, Ana M.; Hillberry, Russell
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Trabalho em Andamento
EN_US
Relevância na Pesquisa
25.86%
Freight forwarders play a key role in moving goods across international borders. They arrange transport, oversee customs clearance on behalf of their clients, and more generally troubleshoot issues that arise while goods are in transit. This paper reports the results from a survey of 153 freight forwarding firms in Serbia. Respondents report on firm characteristics, operational choices, and conditions at the border posts and terminals where imported goods are cleared for release. One key purpose of the study is to investigate operational trade-offs between time and cost that arise when import shipments are in transit. In three of four hypotheticals, respondents suggest that money savings dominate time savings. Responses regarding real operational decisions such as route choices reinforce this finding. Respondents also reported penalty rates for late delivery of import shipments as well as the value of a typical import shipment. From these responses, it is estimated that the contracted value of one additional (unexpected) day of delivery time in Serbia appears to be approximately 1 percent of the value of the underlying shipment.

Republic of India Manufacturing Plan Implementation

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Trabalho em Andamento
EN_US
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25.82%
This set of reports on manufacturing plans implementation in India includes the following: (1) A new agenda. Improving the competitiveness of the textiles and apparel value chain in India report is structured as follows: section one sets out the context, describing trends in global markets and in the textiles and apparel supply chain in India; section two analyzes in detail the choke points that are hindering the growth of the latter; section three sets out a reform agenda to address them; and section four concludes. (2) Fast tracking Indias electronics manufacturing industry. Business environment and industrial policy examines the prospects for India to meet its potential. Drawing on extensive survey questionnaires and interviews with key industry players (both domestic and foreign) and relevant government agencies, this study identifies major challenges India-based companies face in engaging in electronics manufacturing. The analysis culminates in detailed policy suggestions for regulatory reform and support policies needed to unblock barriers to investment in this industry and to fast-track it’s upgrading through innovation. (3) Supply chain delays and uncertainty in India. The hidden constraint on manufacturing growth report provides the context of the freight and logistics industry in India; describes the headline impacts of its performance on manufacturing firms; explores variations in this impact and causes thereof; and concludes with a more detailed look at the reform agenda this motivates.

Review of Logistics Service Regulations for Freight Forwarding Businesses

Watanuki, Maika
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Trabalho em Andamento
EN_US
Relevância na Pesquisa
25.86%
Regulatory frameworks on logistics regulations are often opaque, especially in developing countries, because of the complex nature of logistics services. World Bank client countries have faced difficulty finding the issues that hinder them from improving logistics competence. Therefore, it is beneficial to understand how the logistics service industry is regulated and what should be addressed in building the regulatory framework to improve logistics competence. This note proposes questions to be addressed for beneficial regulations by reviewing existing logistics service regulations in 14 countries, particularly regulations for the freight forwarding industry. These questions will help in assessing a regulatory framework and identifying regulatory weaknesses. This note suggests that the regulatory framework should take into consideration national recognition of freight forwarding business, an institutional arrangement with clear division of responsibility among stakeholders, and streamlined but flexible regulations adapted to the country context.

Trends in Trade and Logistics : An East Asian Perspective

Carruthers, Robin; Bajpai, Jitendra N.
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
35.82%
There are five sections in this report. The first section analysis growth, poverty reduction, trade and logistics. The study indicates that a stimulus in economic growth tends to reduce poverty. Section two analysis global trends in transport and logistics that determine the competitive advantage and growth performance of trading in global economy. Transport and logistics have benefited from technological and institutional changes, and has developed the maritime transport, warehousing facilities, and communication. The net result has been to facilitate globalization. Section three analysis trade led growth in East Asia. The sustained growth performance is usually attributed to the region's global integration. Section four: Logistics in East Asia - the single most important impact of globalization in East Asian countries has been the integration of local production and supply. Section five - a strategy to stimulate trade-led poverty reduction. This analysis has demonstrated the significance of the role of trade in accelerating economic growth and reducing poverty. In addition...

Study on Regulation of Private Operators in the Port of Djibouti

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Economic & Sector Work :: Other Infrastructure Study; Economic & Sector Work
ENGLISH; EN_US
Relevância na Pesquisa
25.85%
Within a partnership framework with the Emirate of Dubai, the government of Djibouti has developed, during the last decade, an outstanding port and logistics hub with few precedents in other African countries. The objective of the present study is to strengthen the competitiveness of the ports of Djibouti (old port of Djibouti and new port of Doraleh) and ensure their medium-term and long-term development by designing a modern and efficient regulation system for private port operators, and specifically addressing issues related to the quality of service and pricing, in addition to institutional related issues. The port of Djibouti's competitiveness can be measured by its capacity to counter competition from other ports through the quality of its infrastructures and services, performance and port costs. Real or potential competition facing the port of Djibouti concerns non-captive traffic and its two components, transit and transshipment traffic. The port of Djibouti's natural competitors for Ethiopia's transit traffic are the ports of Berbera...

A Briefing Note on the Port Sector in Bangladesh

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Economic & Sector Work :: Pre-2003 Economic or Sector Report; Economic & Sector Work
ENGLISH; EN_US
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25.85%
Traffic at Chittagong Port, which handles 90 percent of Bangladesh's foreign trade, has been growing rapidly. The volume of containers handled has increased by over 10 percent a year over the last decade and a similar or faster growth rate is projected for the foreseeable future. Chittagong Port has not responded to this demand growth effectively, resulting in congestions and delays at the port, as well as high costs to port users. The delays and uncertainties in port services seriously undermine the economy's productivity and international trading links. Improving both port operations and on-ward inland transportation system will be fundamental to maintain and improve the international competitiveness of the Bangladesh economy. The productivity at Chittagong port is the lowest among major ports in the region by most measurements. The impact of low productivity in Chittagong port is made worse by the poor inland transport distribution system for containers in the country. Chittagong port is the only major port in South Asia that has no private sector operator in its terminal operations and much of the port's services are run by public monopoly...

Kenya’s Infrastructure : A Continental Perspective

Briceno-Garmendia, Cecilia M.; Shkaratan, Maria
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
ENGLISH
Relevância na Pesquisa
25.94%
In the past decade, infrastructure contributed 0.5 percentage points to Kenya's annual per capita GDP growth. Raising the country s infrastructure endowment to that of Africa's middle-income countries could increase that contribution by 3 percentage points. Several accomplishments are notable. More than 90 percent of the population has access to GSM cell signals. A successful public-private partnership in air transport has made Kenya's airline a top carrier in the region and its international airport a key gateway to Africa. Institutional reforms in the power sector have reduced the burden of subsidies on the public by approximately 1 percent of GDP. But the power sector continues to pose Kenya's greatest infrastructure challenge. Over the next decade, current capacity will have to double. A second challenge is to improve the efficiency of operations at the Port of Mombasa. Other concerns include low levels of access to household services, underfunding of road maintenance, and negative progress on the Millennium Development Goals for water supply and sanitation. Addressing Kenya's infrastructure deficit will require sustained expenditures of approximately $4 billion per year (20 percent of GDP) over the next decade. As of 2006...

Ethiopia’s Infrastructure : A Continental Perspective

Foster, Vivien; Morella, Elvira
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
ENGLISH
Relevância na Pesquisa
35.77%
Infrastructure contributed 0.6 percentage points to Ethiopia's annual per capita GDP growth over the last decade. Raising the country's infrastructure endowment to that of the region's middle-income countries could add an additional 3 percentage points to infrastructure's contribution to growth. Ethiopia's infrastructure successes include developing Ethiopia Airlines, a leading regional carrier; upgrading its network of trunk roads; and rapidly expanding access to water and sanitation.The country's greatest infrastructure challenge lies in the power sector, where a further 8,700 megawatts of generating plant are needed over the next decade, implying a doubling of current capacity. The transport sector faces the challenges of low levels of rural accessibility and inadequate road maintenance. Ethiopia s ICT sector currently suffers from a poor institutional and regulatory framework. Addressing Ethiopia's infrastructure deficit will require a sustained annual expenditure of $5.1 billion over the next decade. The power sector alone requires $3.3 billion annually...

South Sudan’s Infrastructure : A Continental Perspective

Ranganathan, Rupa; Briceno-Garmendia, Cecilia M.
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
ENGLISH
Relevância na Pesquisa
35.72%
Newly independent South Sudan faces a challenge in making its own way in infrastructure development. Despite earning $6 billion in oil revenues since 2005, South Sudan's spending has not been proportional to its income, but rather has lagged behind North Sudan's development of infrastructure and social support. South Sudan benefitted from strong donor support during 2004-10, the interim period defined by the Comprehensive Peace Agreement. It focused on reestablishing regional transport links and access to seaports as well as rehabilitating its ports, airstrips, and single rail line. South Sudan also successfully liberalized the ICT sector. Nonetheless, the new country's infrastructure remains in such a dismal state that it is difficult to pinpoint a single most pressing challenge. The transport sector accounts for half of the country's spending needs, and water and sanitation account for a further quarter of the total. But so many improvements are needed that the nation cannot realistically catch up with its neighbors within 10 years...

Consolidating and Accelerating Exports in Bangladesh : A Policy Agenda

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Economic & Sector Work :: Foreign Trade, FDI, and Capital Flows Study; Economic & Sector Work
ENGLISH; EN_US
Relevância na Pesquisa
35.78%
For Bangladesh to become a middle-income country, growth in exports needs to accelerate exports of basic garments will continue to be important in the near future, but Bangladesh's competitive advantage in this area could erode over time. As such, looking ahead, accelerating exports will require not only consolidating existing strengths in basic garments but diversifying gradually into other products such as higher value garment and service exports. Forward-looking policymaking requires that measures be put in place now to encourage such diversification in future, while building on existing strengths. How can Bangladesh make this happen? Available research shows that the infrastructure deficit, especially energy, as well as lack of appropriate skills and the weak regulatory environment continue to hinder exports from Bangladesh. These weaknesses still persist. To complement work done so far, this report focuses on the role of trade logistics, skills and compliance with labor standards in consolidating existing strengths and moving to higher value products...

Yemen, Republic of - Republic of Yemen Air Transport Sector : Strategy Note

World Bank
Fonte: World Bank Publicador: World Bank
Tipo: Economic & Sector Work :: Other Infrastructure Study
ENGLISH
Relevância na Pesquisa
35.72%
Yemen, the fastest urbanizing country in the Middle East and North Africa region, has a very limited natural resource base and the efficiency of its cities is therefore essential for its future economic growth. However, this efficiency is increasingly handicapped by the poor performance of urban transport, especially in the capital Sana'a. This report presents the main findings of this review and makes key recommendations to improve the efficiency of urban transport in Sana'a. It contains the following chapters: a first chapter presents the general context of the study, characterized by fast demographic and spatial growth in Sana'a, causing major difficulties in terms of urban transport management; a second chapter analyses and describes the main underlying issues affecting the performance and efficiency of Sana'a transport system; a third chapter presents institutional, technical and financing recommendations to improve the performance of Sana'a transport system; and a fourth chapter presents a tentative three-year action plan for implementation of the recommendations.

Tanzania’s Infrastructure : A Continental Perspective

Shkaratan, Maria
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
ENGLISH
Relevância na Pesquisa
35.84%
Infrastructure contributed 1.3 percentage points to Tanzania's annual per capital GDP growth during the 2000s. If the country's infrastructure endowment were improved to the level of the African leader, Mauritius, annual per capita growth rates could increase by 3.4 percent. Tanzania has made great progress in reforming its trunk roads, improving the quality of the road network. The country has also seen significant gains in ICT networks, and has one of the most competitive domestic air transport sectors in Africa. The power sector poses Tanzania's most serious infrastructure challenge. Despite significant improvements in pricing and operational performance in recent years, inefficiency still absorbs about 1.4 percent of GDP. Moreover, due to heavy reliance on hydro-power the sector remains vulnerable to climate variability. The port of Dar es Salaam also suffers from performance problems as rapid traffic growth has increasingly exposed deficiencies in storage and access to the port. Poor access to safe water is another challenge...