528 research outputs found
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Rarity of monodominance in hyperdiverse Amazonian forests.
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors
Diseases of the nervous system of cattle in Mato Grosso do Sul, Brazil : 1082 cases
Foi realizado um estudo retrospectivo de janeiro de 2008 a dezembro de 2012 com base nos laudos de necropsia do Laboratório de Anatomia Patológica (LAP) da Faculdade de Medicina Veterinária e Zootecnia (FAMEZ), Universidade Federal de Mato Grosso do Sul (UFMS), com o intuito de descrever quais as doenças que afetam o sistema nervoso de bovinos que ocorrem no Mato Grosso do Sul. Os casos consistiam de acompanhados por técnicos do LAP e encaminhados por médicos veterinários que atuam no campo (autônomos ou do serviço veterinário oficial). De 1082 materiais analisados, 588 apresentavam histórico de sinais clínicos neurológicos. Destes, 341 (53,75%) tiveram diagnóstico correspondente a doenças neurológicas e 247 (46,25%) tiveram diagnóstico inconclusivos. As fichas clínico epidemiológicas foram revisadas para determinar dados referentes a epidemiologia, aos sinais clínicos e às alterações macroscópicas e microscópicas. O botulismo (16,67%), a raiva (15,92%), a polioencefalomalacia (8,05%) e a encefalite por herpesvirus bovino (4,31%) foram as enfermidade de maior frequência. Outras doenças como meningoencefalite não supurativa (2,62%), meningoencefalite supurativa (1,50%), abscessos cerebrais e osteomielite por compressão medular (1,31%), tétano (1,12%), hipotermia (0,94%), babesiose cerebral (0,75%), febre catarral maligna (0,37%) e lesões sugestivas de intoxicação por oxalato (0,19%) foram ocasionalmente diagnosticadas. Em nenhum dos casos foram observadas lesões que pudessem sugerir encefalopatia espongiforme bovina.The aim of this study was to describe the types of diseases that affect the nervous system of cattle from the State of Mato Grosso do Sul, Brazil. A retrospective study from January 2008 to December 2012 was perfomed, based on reports of cattle autopsies autopsy carried out by the Laboratório de Anatomia Patológica (LAP), Faculdade de Medicina Veterinária e Zootecnia (FAMEZ), Universidade Federal de Mato Grosso do Sul (UFMS). The material came from cases attended and forwarded to LAP by practicing veterinarians autonomous and from the official veterinary service. From 1028 cases studied, 588 presented a history of neurological clinical signs, 341 (53.75%) of which were diagnosed as affected bytrue neurological disease, and 247 (46.25%) had inconclusive diagnosis. The clinical records were reviewed to determine epidemiology, clinical signs, and gross and histopathological features. The most frequent diseases were botulism (16.67%), rabies (15.92%), polioencephalomalacia (8.05%), and herpesviral meningoencephalitis (4.31%). Other conditions were diagnosed occasionally, and included non suppurative meningoencephalitis (2.62%), suppurative meningoencephalitis (1.50%), brain abscesses and osteomyelitis caused by spinal cord compression (1.31%), tetanus (1.12%), hypothermia (0.94%), cerebral babesiosis (0.75%), malignant catarrhal fever (0.37%), and cases suggestive of oxalate poisoning (0.19%). No cases with lesions that may suggest of bovine spongiform encephalopathy were observed
Presidential Commission on the Supreme Court of the United States Final Report
On April 9, 2021, President Joseph R. Biden, Jr. issued Executive Order 14023 establishing this Commission, to consist of “individuals having experience with and knowledge of the Federal judiciary and the Supreme Court of the United States.” The Order charged the Commission with producing a report for the President that addresses three sets of questions. First, the Report should include “[a]n account of the contemporary commentary and debate about the role and operation of the Supreme Court in our constitutional system and about the functioning of the constitutional process by which the President nominates and, by and with the advice and consent of the Senate, appoints Justices to the Supreme Court.” Second, the Report should consider the “historical background of other periods in the Nation’s history when the Supreme Court’s role and the nominations and advice-and-consent process were subject to critical assessment and prompted proposals for reform.” Third, the Report should provide an analysis of the principal arguments for and against particular proposals to reform the Supreme Court, “including an appraisal of [their] merits and legality,” and should be informed by “a broad spectrum of ideas.”
The Report begins by explaining the genesis of today’s Court reform debate, including by identifying developments that gave rise to President Biden’s decision to issue the April 2021 Executive Order, particularly the debates surrounding the most recent nominations. This Introduction emphasizes that the Court’s composition and jurisprudence long have been subjects of public controversy and debate in the nation’s civic life: The Court serves as a crucial guardian of the rule of law and also plays a central role in major social and political conflicts. Its decisions have profound effects on the life of the nation. Though conflict surrounding the processes by which the President nominates and the Senate confirms Justices is not new, it has become more intensely partisan in recent years.
The Introduction also articulates three common and interrelated ideas frequently invoked in reform debates and throughout the Chapters of the Report: the importance of protecting or enhancing the Court’s legitimacy; the role of judicial independence in our system of government; and the value of democracy and its relationship to the Supreme Court’s decisionmaking. These important ideas can mean different things to different people. The Introduction discusses the range of meanings ascribed to these terms, with the aim of clarifying how they are deployed in arguments for and against reform
In vitro and in vivo antitumor effects of the flavonol glycosides isolated of Herissantia crispa (L.) Brizicky
This paper describes the cytotoxic and antitumoral activities of kaempferol 3-O-(6”-O-E-pcoumaroyl)-β-D-glucopyranoside (tiliroside), kaempferol 3,7-di-O-α-L-rhamnoside (dhiramnoside) and of the mixture of sitosteryl-3-O-β-D-glucopyranoside and stigmasteryl-3-O-β-D-glucopyranoside (GM) isolated of the Herissantia crispa. The compounds did not present cytotoxic activity against NCI-H292, HEp-2 and KB cells. In vivo, dhiramnoside did not present significant inhibitory activity of the growth of sarcoma 180 when compared with the control group; however, tiliroside and GM-treated animals showed a high inhibition rate in the growth of the tumor. Tiliroside inhibits significantly the growth of the carcinoma of Ehrlich. In conclusion, tiliroside exhibited promising antitumor effects without an expressive toxicity.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Electrostatic forces and the frequency spectrum of a monolayer solid of linear molecules on graphite
Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates
Indaga sobre los patrones geográficos y los correlatos ecológicos en la distribución geográfica de los modos de dispersión arbórea más comunes en la Amazonia (endozoocoria, sinzoocoria, anemoocoria e hidrocoria). Se examina si la abundancia proporcional de estos modos de dispersión podría explicarse por la disponibilidad de agentes dispersores (hipótesis de disponibilidad de dispersores) y/o la disponibilidad de recursos para la poducción de frutos zoocorios (hipótesis de disponibilidad de recursos). Para ello se usaron parcelas de inventario de árboles establecidas entre 1934 y 2019, con un diámetro a la altura del pecho (DAP) ≥ 9,55 cm. Ubicados en las selvas tropicales de tierras bajas de la cuenca del río Amazonas y el Escudo Guayanés. Se asignaron modos de dispersión a un total de 5433 especies y morfoespecies en 1877 parcelas de inventario de árboles en bosques de abeto, inundados estacionalmente y permanentemente inundados. Se investigaron los patrones geográficos en la abundancia proporcional de los modos de dispersión. Se realizó una prueba de distancia media entre pares ponderada por abundancia (MPD) y ajustamos modelos lineales generalizados (GLM) para explicar la distribución geográfica de los modos de dispersión. La anemocoria se asoció significativa y positivamente con la velocidad media anual del viento, y la hidrocoria fue significativamente mayor en los bosques inundados. Los modos de dispersión no mostraron consistentemente asociaciones significativas con la disponibilidad de recursos para la construcción de frutos zoochorous. Una menor disimilitud en los modos de dispersión, resultante de una mayor dominancia de la endozoocoria, se produjo en los bosques de abeto (excluyendo los podzoles) en comparación con los bosques inundados. La hipótesis dispersor-disponibilidad fue bien apoyada para los modos de dispersión abióticos (anemochoria e hidrochoria). La disponibilidad de recursos para la construcción de frutos zoocorios parece una explicación poco probable para la distribución de los modos de dispersión en la Amazonia. La asociación entre los frugívoros y la abundancia proporcional de zoocoría requiere más investigación, ya que el reclutamiento de árboles no sólo depende de los vectores de dispersión, sino también de las condiciones que favorecen o limitan el reclutamiento de plántulas en los distintos tipos de bosque.Revisión por pares
Late Quaternary landscape evolution of northeastern Amazonia from pollen and diatom records
Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates
Unidad de excelencia María de Maeztu CEX2019-000940-MAim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types
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Impact of pre-Columbian 'geoglyph' builders on Amazonian forests
Over 450 pre-Columbian (pre-AD1492) geometric ditched enclosures ('geoglyphs') occupy ca. 13,000 km2 of Acre state, Brazil, representing a key discovery of Amazonian archaeology. These huge earthworks were concealed for centuries under terra firme (upland interfluvial) rainforest, directly challenging the 'pristine' status of this ecosystem and its perceived vulnerability to human impacts. We reconstruct the environmental context of geoglyph construction and the nature, extent and legacy of associated human impacts. We show that bamboo forest dominated the region for ≥6000 y and that only small, temporary clearings were made to build the geoglyphs; however, construction occurred within anthropogenic forest that had been actively managed for millennia. In the absence of widespread deforestation, exploitation of forest products shaped a largely forested landscape that survived intact until the late 20th century
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