2,098 research outputs found
Influence of hyper-energetic, high-fat feeding on circulating hepatokines in healthy men: a randomised crossover study [Abstract]
No description supplie
Complex dynamics of defective interfering baculoviruses during serial passage in insect cells
Defective interfering (DI) viruses are thought to cause oscillations in virus levels, known as the 'Von Magnus effect'. Interference by DI viruses has been proposed to underlie these dynamics, although experimental tests of this idea have not been forthcoming. For the baculoviruses, insect viruses commonly used for the expression of heterologous proteins in insect cells, the molecular mechanisms underlying DI generation have been investigated. However, the dynamics of baculovirus populations harboring DIs have not been studied in detail. In order to address this issue, we used quantitative real-time PCR to determine the levels of helper and DI viruses during 50 serial passages of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in Sf21 cells. Unexpectedly, the helper and DI viruses changed levels largely in phase, and oscillations were highly irregular, suggesting the presence of chaos. We therefore developed a simple mathematical model of baculovirus-DI dynamics. This theoretical model reproduced patterns qualitatively similar to the experimental data. Although we cannot exclude that experimental variation (noise) plays an important role in generating the observed patterns, the presence of chaos in the model dynamics was confirmed with the computation of the maximal Lyapunov exponent, and a Ruelle-Takens-Newhouse route to chaos was identified at decreasing production of DI viruses, using mutation as a control parameter. Our results contribute to a better understanding of the dynamics of DI baculoviruses, and suggest that changes in virus levels over passages may exhibit chaos.The authors thank Javier Carrera, Just Vlak and Lia Hemerik for helpful discussion. MPZ was supported by a Rubicon Grant from the Netherlands Organization for Scientific Research (NWO, www.nwo.nl) and a 'Juan de la Cierva' postdoctoral contract (JCI-2011-10379) from the Spanish 'Secretaria de Estado de Investigacion, Desarrollo e Innovacion'. JS was supported by the Botin Foundation. SFE was supported by grant BFU2012-30805, also from the Spanish 'Secretaria de Estado de Investigacion, Desarrollo e Innovacion'.Zwart, MP.; Pijlman, G.; Sardanyes Cayuela, J.; Duarte, J.; Januario, C.; Elena Fito, SF. (2013). Complex dynamics of defective interfering baculoviruses during serial passage in insect cells. Journal of Biological Physics. 39(2):327-342. doi:10.1007/s10867-013-9317-9S327342392Von Magnus, P.: Incomplete forms of influenza virus. Adv. Virus. Res. 2, 59–79 (1954)Huang, A.S.: Defective interfering viruses. Annu. Rev. Microbiol. 27, 101–117 (1973)Kool, M., Voncken, J.W., Vanlier, F.L.J., Tramper, J., Vlak, J.M.: Detection and analysis of Autographa californica nuclear polyhedrosis-virus mutants with defective interfering properties. 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Livelihood responses to Lantana camara invasion and biodiversity change in southern India: application of an asset function framework
Natural resources play key roles as assets in the livelihoods of rural communities. However, the benefits of these assets in livelihoods are frequently conceived narrowly as income generating or vulnerability reducing. We contend that they have other important roles to play in poverty reduction and livelihood change. In this paper we use a case study of two ethnic communities in a village in southern India to investigate livelihood responses to change in forest biodiversity through an examination of changes in attributes of natural assets resulting from the invasion of Lantana camara and wider socio-economic change. The invasion of forest by Lantana has contributed to changes in the attributes and functions of four key natural assets: forest grazing, bamboo for basketry, Phoenix loureie for brooms, and wild yams. We observe that differences in households’ and individuals’ ability to substitute important functions of lost or declining assets affect their ability to adapt to changes in resource availability and attributes. Analysing changes in asset attributes for different user groups allows the social effects of environmental change to be disaggregated
Cluster Lenses
Clusters of galaxies are the most recently assembled, massive, bound
structures in the Universe. As predicted by General Relativity, given their
masses, clusters strongly deform space-time in their vicinity. Clusters act as
some of the most powerful gravitational lenses in the Universe. Light rays
traversing through clusters from distant sources are hence deflected, and the
resulting images of these distant objects therefore appear distorted and
magnified. Lensing by clusters occurs in two regimes, each with unique
observational signatures. The strong lensing regime is characterized by effects
readily seen by eye, namely, the production of giant arcs, multiple-images, and
arclets. The weak lensing regime is characterized by small deformations in the
shapes of background galaxies only detectable statistically. Cluster lenses
have been exploited successfully to address several important current questions
in cosmology: (i) the study of the lens(es) - understanding cluster mass
distributions and issues pertaining to cluster formation and evolution, as well
as constraining the nature of dark matter; (ii) the study of the lensed objects
- probing the properties of the background lensed galaxy population - which is
statistically at higher redshifts and of lower intrinsic luminosity thus
enabling the probing of galaxy formation at the earliest times right up to the
Dark Ages; and (iii) the study of the geometry of the Universe - as the
strength of lensing depends on the ratios of angular diameter distances between
the lens, source and observer, lens deflections are sensitive to the value of
cosmological parameters and offer a powerful geometric tool to probe Dark
Energy. In this review, we present the basics of cluster lensing and provide a
current status report of the field.Comment: About 120 pages - Published in Open Access at:
http://www.springerlink.com/content/j183018170485723/ . arXiv admin note:
text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author
Recommended from our members
Contested Compliance Regimes in Global Production Networks: Insights from the Bangladesh Garment Industry
This article reports the findings of a field study on the emergence of collective agreements led by global brands enacting compliance measures to improve safety and working conditions in the Bangladesh garment industry. We explore how key actors in the Bangladesh garment sector who constitute the local production system of the global supply chain experienced the implementation of global agreements on factory safety. We argue that global safety compliance measures through multi-stakeholder initiatives provide legitimacy to multinational corporations and their global brands but do little to address the structural problems arising from exploitative pricing and procurement practices, which are the key reasons for deplorable working conditions in garment factories. Our findings indicate that neoliberal development policies of the state, where local economies are incorporated into global production networks, resulted in differential treatment and regulation of specific populations that comprise garment factory workers. The reconfiguration of state power to meet the demands of global supply chains also involved use of state violence to suppress dissent while undermining labour rights and working conditions. Our article contributes to the politicization of multinational corporations in global production chains by showing how contestations between workers, factory owners, the state, trade unions and multinational corporations create new private forms of governance and new regimes of compliance in the industr
Population Genetics of Franciscana Dolphins (Pontoporia blainvillei): Introducing a New Population from the Southern Edge of Their Distribution
Due to anthropogenic factors, the franciscana dolphin, Pontoporia blainvillei, is the most threatened small cetacean on the Atlantic coast of South America. Four Franciscana Management Areas have been proposed: Espiritu Santo to Rio de Janeiro (FMA I), São Paulo to Santa Catarina (FMA II), Rio Grande do Sul to Uruguay (FMA III), and Argentina (FMA IV). Further genetic studies distinguished additional populations within these FMAs. We analyzed the population structure, phylogeography, and demographic history in the southernmost portion of the species range. From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range. The haplotype network did not show an apparent phylogeographical signal for the southern FMAs. Two populations were identified: Monte Hermoso (MH) and Necochea (NC)+Claromecó (CL)+Río Negro (RN). The low levels of genetic variability, the relative constant size over time, and the low levels of gene flow may indicate that MH has been colonized by a few maternal lineages and became isolated from geographically close populations. The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations. Additionally, RN may have experienced a recent split from CL and NC; current high levels of gene flow may be occurring between the latter ones. FMA IV would comprise four franciscana dolphin populations: Samborombón West+Samborombón South, Cabo San Antonio+Buenos Aires East, NC+CL+Buenos Aires Southwest+RN and MH. Results achieved in this study need to be taken into account in order to ensure the long-term survival of the species.Fil: Gariboldi, María Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Tunez, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Luján; ArgentinaFil: Dejean, Cristina Beatriz. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Ciencias Antropológicas. Sección Antropología Biológica; ArgentinaFil: Failla, Mauricio. Fundación Cethus; ArgentinaFil: Vitullo, Alfredo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Negri, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; ArgentinaFil: Cappozzo, Humberto Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin
Public Opinion on Migration and the Role of the Media in the Context of the “European Refugee Crisis”
This book presents an overview of European migration policy and the various institutional arrangements within and between various actors, such as local councils, local media, local economies, and local civil society initiatives. Both the role of local authorities in this policy field and their cooperation with civil society initiatives or networks are under-explored topics for research. In response, this book provides a range of detailed case studies focusing on the six main groups of national and administrative traditions in Europe: Germanic, Scandinavian, Napoleonic, Southeastern European, Central-Eastern European and Anglo-Saxon.Peer reviewe
The Formation and Evolution of the First Massive Black Holes
The first massive astrophysical black holes likely formed at high redshifts
(z>10) at the centers of low mass (~10^6 Msun) dark matter concentrations.
These black holes grow by mergers and gas accretion, evolve into the population
of bright quasars observed at lower redshifts, and eventually leave the
supermassive black hole remnants that are ubiquitous at the centers of galaxies
in the nearby universe. The astrophysical processes responsible for the
formation of the earliest seed black holes are poorly understood. The purpose
of this review is threefold: (1) to describe theoretical expectations for the
formation and growth of the earliest black holes within the general paradigm of
hierarchical cold dark matter cosmologies, (2) to summarize several relevant
recent observations that have implications for the formation of the earliest
black holes, and (3) to look into the future and assess the power of
forthcoming observations to probe the physics of the first active galactic
nuclei.Comment: 39 pages, review for "Supermassive Black Holes in the Distant
Universe", Ed. A. J. Barger, Kluwer Academic Publisher
Increased Vascularity in Cervicovaginal Mucosa with Schistosoma haematobium Infection
Schistosomiasis is a fresh water parasite infection that affects millions of people, especially in Africa. Recent knowledge about the genital manifestations of schistosomiasis; especially its possible association with human immunodeficiency virus (HIV) infection, has led to increased focus on this neglected tropical disease. Millions of women remain undiagnosed for genital schistosomiasis, and may suffer from abnormal mucosal blood vessels, contact bleeding and lesions named sandy patches. This study analyses a unique selection of female genital biopsies containing parasite eggs. Protein detection and standard histopathological assessment are combined to quantify and study the characteristics of the mucosal blood vessels surrounding the eggs. Our results show that the genital mucosa with parasite eggs is more vascularised compared to healthy tissue, and that viable eggs tend to be surrounded by proliferating blood vessels. These findings have not yet been correlated directly to clinical manifestations. Further studies are needed in order to provide clinical advice on the risks and consequences of mucosal lesions particular to female genital schistosomiasis
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