MicroRNA networks direct neuronal development and plasticity

MicroRNAs (miRNAs) constitute a class of small, non-coding RNAs that act as post-transcriptional regulators of gene expression. In neurons, the functions of individual miRNAs are just beginning to emerge, and recent studies have elucidated roles for neural miRNAs at various stages of neuronal development and maturation, including neurite outgrowth, dendritogenesis, and spine formation. Notably, miRNAs regulate mRNA translation locally in the axosomal and synaptodendritic compartments, and thereby contribute to the dynamic spatial organization of axonal and dendritic structures and their function. Given the critical role for miRNAs in regulating early brain development and in mediating synaptic plasticity later in life, it is tempting to speculate that the pathology of neurological disorders is affected by altered expression or functioning of miRNAs. Here we provide an overview of recently identified mechanisms of neuronal development and plasticity involving miRNAs, and the consequences of miRNA dysregulation

Anytime Algorithms for Multi-Objective Hub Location Problems

In many logistic, telecommunications and computer networks, direct routing of commodities between any origin and destination is not viable due to economic and technological constraints. Hub locations problems (HLPs) are considered in that cases, where the design of these networks are optimized based on some objective(s) related on the cost or service. A huge number of papers have been published since the seminal work of O’Kelly. Early works were focused on analogue facility location problems, considering some assumptions to simplify network design. Recent works have studied more complex models that relax some of these assumptions and incorporate additional real-life features. In most HLPs considered in the literature, the input parameters are assumed to be known and deterministic. However, in practice, this assumption is unrealistic since there is a high uncertainty on relevant parameters, such as costs, demands or even distances. As a result, a decision maker usually prefer several solutions with a low uncertainty in their objectives functions. In this work, anytime algorithms are proposed to solve the multi-objective hub location problems with uncertainty. The proposed algorithms can be stopped at any time, yielding a set of efficient solutions (belonging to the Pareto front) that are well spread in the objective space.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Solving multi-objective hub location problems by hybrid algorithms

In many logistic, telecommunications and computer networks, direct routing of commodities between any origin and destination is not viable due to economic and technolog- ical constraints. In that cases, a network with centralized units, known as hub facilities, and a small number of links is commonly used to connect any origin-destination pair. The purpose of these hub facilities is to consolidate, sort and transship e ciently any commodity in the network. Hub location problems (HLPs) consider the design of these networks by locating a set of hub facilities, establishing an interhub subnet, and routing the commodities through the network while optimizing some objective(s) based on the cost or service. Hub location has evolved into a rich research area, where a huge number of papers have been published since the seminal work of O'Kelly [1]. Early works were focused on analogue facility location problems, considering some assumptions to simplify network design. Recent works [2] have studied more complex models that relax some of these assumptions and in- corporate additional real-life features. In most HLPs considered in the literature, the input parameters are assumed to be known and deterministic. However, in practice, this assumption is unrealistic since there is a high uncertainty on relevant parameters, such as costs, demands or even distances. In this work, we will study the multi-objective hub location problems with uncertainty.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Enabling relay selection in non-orthogonal multiple access networks: direct and relaying mode

In this paper, we consider downlink non-orthogonal multiple access (NOMA) in which the relay selection (RS) scheme is enabled for cooperative networks. In particular, we investigate impact of the number of relays on system performance in term of outage probability. The main factors affecting on cooperative NOMA performance are fixed power allocations coefficients and the number of relay. This paper also indicate performance gap of the outage probabilities among two users the context of NOMA. To exhibit the exactness of derived formula, we match related results between simulation and analytical methods. Numerical results confirms that cooperative NOMA networks benefit from increasing the number of relay

FAMILY AND COMMUNITY NETWORKS IN MEXICO-U.S. MIGRATION

A household's decision to send migrants is based on information the household has on the expected returns and the costs of migration. Information on migration flows from both family migrant networks and community migrant networks. Direct assistance - in the form of money, housing, transportation, and food - is often provided to migrants by these networks, thus reducing the costs of migration. Using data from a national survey of rural Mexican households, we show the importance of networks in both the decision to migrate and the level of migration. We find that community and family networks are substitutes in the production of information and assistance suggesting that, once migration is well established in a community, family networks become less important. In addition, the development of strong community networks erases the role of household characteristics in migration, allowing those initially least favored to also participate in migration. Results suggest that policies designed to reduce Mexico-U.S. migration should focus on regions where migrant networks are yet weakly developed since, once strong community networks become established, reducing migration would require much higher levels of public investment.Migration, networks, Mexico, Consumer/Household Economics, Labor and Human Capital,

Job contact networks and the ethnic minorities

This paper examines the job finding methods of different ethnic groups in the UK. The theoretical framework shows that less assimilated ethnic unemployed workers are more likely to use their friends and family as their main method of search but they have less chance of finding a job using this method compared to whites and more assimilated ethnic unemployed workers that use formal job search methods (adverts, employment agencies etc.). Using data from the UK Quarterly Labour Force Survey (QLFS), we test these hypotheses. Our empirical findings are consistent with the theory since they suggest that, though networks are a popular method of finding a job for the ethnic minorities, they are not necessarily the most effective either in terms of gaining employment or in terms of the level of job achieved. However, there are important differences across ethnic groups with the Pakistani and Bangladeshi groups and those born outside the UK (the least assimilated), losing out disproportionately from using personal networks

The impact of horizontal gene transfer in shaping operons and protein interaction networks – direct evidence of preferential attachment

<p>Abstract</p> <p>Background</p> <p>Despite the prevalence of horizontal gene transfer (HGT) in bacteria, to this date there were few studies on HGT in the context of gene expression, operons and protein-protein interactions. Using the recently available data set on the <it>E. coli </it>protein-protein interaction network, we sought to explore the impact of HGT on genome structure and protein networks.</p> <p>Results</p> <p>We classified the <it>E. coli </it>genes into three categories based on their evolutionary conservation: a set of 2158 <it>Core </it>genes that are shared by all <it>E. coli </it>strains, a set of 1044 <it>Non-core </it>genes that are strain-specific, and a set of 1053 genes that were putatively acquired by horizontal transfer. We observed a clear correlation between gene expressivity (measured by Codon Adaptation Index), evolutionary rates, and node connectivity between these categories of genes. Specifically, we found the <it>Core </it>genes are the most highly expressed and the most slowly evolving, while the <it>HGT </it>genes are expressed at the lowest level and evolve at the highest rate. <it>Core </it>genes are the most likely and <it>HGT </it>genes are the least likely to be member of the operons. In addition, we found the <it>Core </it>genes on average are more highly connected than <it>Non-core </it>and <it>HGT </it>genes in the protein interaction network, however the <it>HGT </it>genes displayed a significantly higher mean node degree than the <it>Core </it>and <it>Non-core </it>genes in the defence COG functional category. Interestingly, <it>HGT </it>genes are more likely to be connected to <it>Core </it>genes than expected by chance, which suggest a model of differential attachment in the expansion of cellular networks.</p> <p>Conclusion</p> <p>Results from our analysis shed light on the mode and mechanism of the integration of horizontally transferred genes into operons and protein interaction networks.</p

Economic, Social, and Environmental Benefits Associated With U.S. Organic Agriculture

This case study reviews the economic, social, and environmental benefits associated with organic agriculture in the United States. Measurable impacts are quantified by comparing indicators of benefits in counties with organic farms and counties without. Statistical differences across counties with and without organic farms provide preliminary evidence that organic farms may generate a variety of direct and indirect benefits. Of 36 indicators tested across a range of economic, social, and environmental benefits, 26 favor organic systems, three favor conventional systems, and seven are neutral. Even though organic farmers are not a large percentage of the total number of U.S. farmers, they may be influencing mainstream agriculture to shift toward greater sustainability

PMD tolerance of 288 Gbit/s Coherent WDM and transmission over unrepeatered 124 km of field-installed single mode optical fiber

Low-cost, high-capacity optical transmission systems are required for metropolitan area networks. Direct-detected multi-carrier systems are attractive candidates, but polarization mode dispersion (PMD) is one of the major impairments that limits their performance. In this paper, we report the first experimental analysis of the PMD tolerance of a 288Gbit/s NRZ-OOK Coherent Wavelength Division Multiplexing system. The results show that this impairment is determined primarily by the subcarrier baud rate. We confirm the robustness of the system to PMD by demonstrating error-free performance over an unrepeatered 124km field-installed single-mode fiber with a negligible penalty of 0.3dB compared to the back-to-back measurements. (C) 2010 Optical Society of Americ