980 resultados para Muller, Manoel Jansen, 1862-1922.
Resumo:
Major General Orde Wingate (1903–44) was the most controversial British military commander of the Second World War, due to his idiosynchratic leadership style, which led some to question his sanity, and his fiercely pro-Zionist stance. More than sixty years after his death he still splits opinion amongst soldiers, academics and writers.
Resumo:
Background Primary bacterial endosymbionts of insects (p-endosymbionts) are thought to be undergoing the process of Muller's ratchet where they accrue slightly deleterious mutations due to genetic drift in small populations with negligible recombination rates. If this process were to go unchecked over time, theory predicts mutational meltdown and eventual extinction. Although genome degradation is common among p-endosymbionts, we do not observe widespread p-endosymbiont extinction, suggesting that Muller's ratchet may be slowed or even stopped over time. For example, selection may act to slow the effects of Muller's ratchet by removing slightly deleterious mutations before they go to fixation thereby causing a decrease in nucleotide substitutions rates in older p-endosymbiont lineages. Methodology/Principal Findings To determine whether selection is slowing the effects of Muller's ratchet, we determined the age of the Candidatus Riesia/sucking louse assemblage and analyzed the nucleotide substitution rates of several p-endosymbiont lineages that differ in the length of time that they have been associated with their insect hosts. We find that Riesia is the youngest p-endosymbiont known to date, and has been associated with its louse hosts for only 13–25 My. Further, it is the fastest evolving p-endosymbiont with substitution rates of 19–34% per 50 My. When comparing Riesia to other insect p-endosymbionts, we find that nucleotide substitution rates decrease dramatically as the age of endosymbiosis increases. Conclusions/Significance A decrease in nucleotide substitution rates over time suggests that selection may be limiting the effects of Muller's ratchet by removing individuals with the highest mutational loads and decreasing the rate at which new mutations become fixed. This countering effect of selection could slow the overall rate of endosymbiont extinction.
Resumo:
Plant traits – the morphological, anatomical, physiological, biochemical and phenological characteristics of plants and their organs – determine how primary producers respond to environmental factors, affect other trophic levels, influence ecosystem processes and services and provide a link from species richness to ecosystem functional diversity. Trait data thus represent the raw material for a wide range of research from evolutionary biology, community and functional ecology to biogeography. Here we present the global database initiative named TRY, which has united a wide range of the plant trait research community worldwide and gained an unprecedented buy-in of trait data: so far 93 trait databases have been contributed. The data repository currently contains almost three million trait entries for 69 000 out of the world's 300 000 plant species, with a focus on 52 groups of traits characterizing the vegetative and regeneration stages of the plant life cycle, including growth, dispersal, establishment and persistence. A first data analysis shows that most plant traits are approximately log-normally distributed, with widely differing ranges of variation across traits. Most trait variation is between species (interspecific), but significant intraspecific variation is also documented, up to 40% of the overall variation. Plant functional types (PFTs), as commonly used in vegetation models, capture a substantial fraction of the observed variation – but for several traits most variation occurs within PFTs, up to 75% of the overall variation. In the context of vegetation models these traits would better be represented by state variables rather than fixed parameter values. The improved availability of plant trait data in the unified global database is expected to support a paradigm shift from species to trait-based ecology, offer new opportunities for synthetic plant trait research and enable a more realistic and empirically grounded representation of terrestrial vegetation in Earth system models.
Resumo:
We report here the protein expression of TRPV1 receptor in axotomized rat retinas and its possible participation in mechanisms involved in retinal ganglion cell (RGC) death. Adult rats were subjected to unilateral, intraorbital axotomy of the optic nerve, and the retinal tissue was removed for further processing. TRPV1 total protein expression decreased progressively after optic nerve transection, reaching 66.2% of control values 21 days after axotomy. The number of cells labeled for TRPV1 in the remnant GCL decreased after 21 days post-lesion (to 63%). Fluoro-jade B staining demonstrated that the activation of TRPV1 in acutely-lesioned eyes elicited more intense neuronal degeneration in the GCL and in the inner nuclear layer than in sham-operated retinas. A single intraocular injection of capsazepine (100 mu M), a TRPV1 antagonist, 5 days after optic nerve lesion, decreased the number of GFAP-expressing Muller cells (72.5% of control values) and also decreased protein nitration in the retinal vitreal margin (75.7% of control values), but did not affect lipid peroxidation. Furthermore, retinal explants were treated with capsaicin (100 mu M), and remarkable protein nitration was then present, which was reduced by blockers of the constitutive and inducible nitric oxide synthases (7-NI and aminoguanidine, respectively). TRPV1 activation also increased GFAP expression, which was reverted by both TRPV1 antagonism with capsazepine and by 7-NI and aminoguanidine. Given that Muller cells do not express TRPV1, we suppose that the increased GFAP expression in these cells might be elicited by TRPV1 activation and by its indirect effect upon nitric oxide overproduction and peroxynitrite formation. We incubated Fluorogold pre-labeled retinal explants in the presence of capsazepine (1 mu M) during 48 h. The numbers of surviving RGCs stained with fluorogold and the numbers of apoptotic cells in the GCL detected with TUNEL were similar in lesioned and control retinas. We conclude that TRPV1 receptor expression decreased after optic nerve injury due to death of TRPV1-containing cells. Furthermore, these data indicate that TRPV1 might be involved in intrinsic protein nitration and Muller cell reaction observed after optic nerve injury. (C) 2010 Elsevier Ltd. All rights reserved.
Resumo:
Den här undersökningen ämnar kartlägga Svenska Skolornas Fredsförenings (SSF) fredarbete under 1920-talet, en ansats som inte tidigare gjorts på detta sätt. Medlemmarna i denna förening arbetade outtröttligt för en fredligare värld, där fredsfostran av unga sågs som den bästa metoden för att få till stånd en internationell varaktig fred. Syftet med undersökningen är att, genom en kvalitativ innehållsanalys av delar av SSFs bevarade tryckta skrifter, beskriva SSFs principer och pedagogiska metoder samt utröna varför de ansåg fredsfostran riktad mot skolan som viktig. Resultaten visar att SSF hade ambitionen att genom internationellt samarbete påverka barnen i en sådan riktning att de aldrig skulle kunna ta till vapen för att lösa konflikter. Istället skulle barn lära sig att tänka kritiskt, vara självständiga och få en förståelse för andra folks kulturer. Genom att respektera och leva efter kristna, jämlika och demokratiska ideal, menade SSF att krig skulle gå att förhindra.
Resumo:
Some of the themes discussed are: • Civic engagement (2) • The Levine family (2) • High school—private (3) • Colby (4) • Colby—student interaction with Waterville Jews (5) • Dating (6, 7, 18-20) • Life in Waterville (8, 10) • Life in Waterville—movies (12-13) • Colby—Greek life (9) • Colby—administration (9-10) • Occupation—real estate development (10-12, 13, 17) • Camp—Arcadia (13-14) • Military service (16) • Civic engagement (22) • Jewish education (23) • Holidays (23-24)
Resumo:
Some of the themes discussed are: • Civic engagement (2) • The Levine family (2) • High school—private (3) • Colby (4) • Colby—student interaction with Waterville Jews (5) • Dating (6, 7, 18-20) • Life in Waterville (8, 10) • Life in Waterville—movies (12-13) • Colby—Greek life (9) • Colby—administration (9-10) • Occupation—real estate development (10-12, 13, 17) • Camp—Arcadia (13-14) • Military service (16) • Civic engagement (22) • Jewish education (23) • Holidays (23-24)