139 research outputs found

    Precision Measurement of 11Li moments: Influence of Halo Neutrons on the 9Li Core

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    The electric quadrupole moment and the magnetic moment of the 11Li halo nucleus have been measured with more than an order of magnitude higher precision than before, |Q| = 33.3(5)mb and mu=3.6712(3)mu_N, revealing a 8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This result is compared to various models that aim at describing the halo properties. In the shell model an increased quadrupole moment points to a significant occupation of the 1d orbits, whereas in a simple halo picture this can be explained by relating the quadrupole moments of the proton distribution to the charge radii. Advanced models so far fail to reproduce simultaneously the trends observed in the radii and quadrupole moments of the lithium isotopes.Comment: 4 pages, 4 figures, 1 tabl

    Cross-species pathogen spillover across ecosystem boundaries: mechanisms and theory

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    Pathogen spillover between different host species is the trigger for many infectious disease outbreaks and emergence events, and ecosystem boundary areas have been suggested as spatial hotspots of spillover. This hypothesis is largely based on suspected higher rates of zoonotic disease spillover and emergence in fragmented landscapes and other areas where humans live in close vicinity to wildlife. For example, Ebola virus outbreaks have been linked to contacts between humans and infected wildlife at the rural-forest border, and spillover of yellow fever via mosquito vectors happens at the interface between forest and human settlements. Because spillover involves complex interactions between multiple species and is difficult to observe directly, empirical studies are scarce, particularly those that quantify underlying mechanisms. In this review, we identify and explore potential ecological mechanisms affecting spillover of pathogens (and parasites in general) at ecosystem boundaries. We borrow the concept of ‘permeability’ from animal movement ecology as a measure of the likelihood that hosts and parasites are present in an ecosystem boundary region. We then discuss how different mechanisms operating at the levels of organisms and ecosystems might affect permeability and spillover. This review is a step towards developing a general theory of cross-species parasite spillover across ecosystem boundaries with the eventual aim of improving predictions of spillover risk in heterogeneous landscapes

    Magnetic Moment of the Fragmentation Aligned 61Fe(9/2)+ Isomer

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    We report on the g factor measurement of the isomer in 61Fe^{61}Fe (E=861keVE^{*}=861 keV). The isomer was produced and spin-aligned via a projectile-fragmentation reaction at intermediate energy, the Time Dependent Perturbed Angular Distribution (TDPAD) method being used for the measurement of the g factor. For the first time, due to significant improvements of the experimental technique, an appreciable residual alignment of the isomer has been observed, allowing a precise determination of its g factor: g=0.229(2)g=-0.229(2). Comparison of the experimental g factor with shell-model and mean field calculations confirms the 9/2+9/2^+ spin and parity assignments and suggests the onset of deformation due to the intrusion of Nilsson orbitals emerging from the νg9/2\nu g_{9/2}.Comment: 4 figures. Submitted to Phys. Rev. Let

    Epidemic growth rates and host movement patterns shape management performance for pathogen spillover at the wildlife–livestock interface

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    Managing pathogen spillover at the wildlife–livestock interface is a key step towards improving global animal health, food security and wildlife conservation. However, predicting the effectiveness of management actions across host–pathogen systems with different life histories is an on-going challenge since data on intervention effectiveness are expensive to collect and results are system-specific.We developed a simulation model to explore how the efficacies of different management strategies vary according to host movement patterns and epidemic growth rates. The model suggested that fast-growing, fast-moving epidemics like avian influenza were best-managed with actions like biosecurity or containment, which limited and localized overall spillover risk. For fast-growing, slower-moving diseases like foot-and-mouth disease, depopulation or prophylactic vaccination were competitive management options. Many actions performed competitively when epidemics grew slowly and host movements were limited, and how management efficacy related to epidemic growth rate or host movement propensity depended on what objectivewas used to evaluatemanagement performance. This framework offers one means of classifying and prioritizing responses to novel pathogen spillover threats, and evaluating current management actions for pathogens emerging at the wildlife–livestock interface. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’

    Marine microbial biodiversity, bioinformatics and biotechnology (M2B3) data reporting and service standards

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    Contextual data collected concurrently with molecular samples are critical to the use of metagenomics in the fields of marine biodiversity, bioinformatics and biotechnology. We present here Marine Microbial Biodiversity, Bioinformatics and Biotechnology (M2B3) standards for “Reporting” and “Serving” data. The M2B3 Reporting Standard (1) describes minimal mandatory and recommended contextual information for a marine microbial sample obtained in the epipelagic zone, (2) includes meaningful information for researchers in the oceanographic, biodiversity and molecular disciplines, and (3) can easily be adopted by any marine laboratory with minimum sampling resources. The M2B3 Service Standard defines a software interface through which these data can be discovered and explored in data repositories. The M2B3 Standards were developed by the European project Micro B3, funded under 7th Framework Programme “Ocean of Tomorrow”, and were first used with the Ocean Sampling Day initiative. We believe that these standards have value in broader marine science

    Efecto del antígeno excretor-secretor de leishmania braziliensis sobre la fagocitosis en macrófagos.

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    Leishmania braziliensis es un flagelado digénico que causa patología en mamíferos.El insecto vector inocula formas promastigotes del parásito en el torrente circulatorio delhospedador. Los parásitos deben ser endocitados rápidamente por los macrófagos u otrosfagocitos, en los que se reproduce como amastigote dentro de una vacuola parasitófora; lospromastigotes que no son internalizados mueren. Se sabe que la activación de los macrófagos, pormoléculas como los lipopolisacáridos (LPS) por ejemplo, producen mediadores químicos queregulan la respuesta inmune humoral y determinan la producción de interleuquinas Th1 o Th2, perose desconoce el efecto de la activación de los macrófagos sobre el proceso de fagocitosis. Por otraparte, se ha visto que el antígeno excretor-secretor producido por promastigotes (AESPL) de L.donovani activa a macrófagos murinos para la producción de interleuquinas pero no se conoce suefecto sobre el proceso de fagocitosis

    Two naphthalene degrading bacteria belonging to the genera Paenibacillus and Pseudomonas isolated from a highly polluted lagoon perform different sensitivities to the organic and heavy metal contaminants

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    Two bacterial strains were isolated in the presence of naphthalene as the sole carbon and energy source from sediments of the Orbetello Lagoon, Italy, which is highly contaminated with both organic compounds and metals. 16S rRNA gene sequence analysis of the two isolates assigned the strains to the genera Paenibacillus and Pseudomonas. The effect of different contaminants on the growth behaviors of the two strains was investigated. Pseudomonas sp. ORNaP2 showed a higher tolerance to benzene, toluene, and ethylbenzene than Paenibacillus sp. ORNaP1. In addition, the toxicity of heavy metals potentially present as co-pollutants in the investigated site was tested. Here, strain Paenibacillus sp. ORNaP1 showed a higher tolerance towards arsenic, cadmium, and lead, whereas it was far more sensitive towards mercury than strain Pseudomonas sp. ORNaP2. These differences between the Gram-negative Pseudomonas and the Gram-positive Paenibacillus strain can be explained by different general adaptive response systems present in the two bacteria

    Neighbourliness, conviviality, and the sacred in Athens’ refugee squats

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    To better understand the range of possibilities and opportunities for (co)existence available to displacement‐affected people, attention must be given to the thick webs of sociality shaping interactions in situations of mass displacement. This paper makes the case that refugee squats in Athens are distinct spaces wherein different understandings of (co)existence converge – spaces whose production is contingent on support from neighbourly relations and networks that are mediated in moments through conceptions of conviviality informed by religion. Based on ethnographic work carried out in 2016 and a spatial analysis of refugee squats in Athens, this paper emphasises neighbourliness and conviviality as they relate to sacred understandings of coexistence. This helps highlight the limits built in to thinking about the movement of refugees from the global South through Euro‐centric ontologies of the social. More than this, following postcolonial debates on the decentring of knowledge production, the research makes manifest how Islamic socio‐cultural memories of jiwār or a right of neighbourliness complicate geographies of humanitarianism that make stark binary assumptions between religious and secular space. In turn, the evidence from Athens indicates that refugee perspectives on neighbourliness are imperfectly translated by migrant rights activists as solidarity, obscuring the different ways Muslim structures of feeling contribute to the production of refugee squats
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