470 research outputs found

    Hidden effects of habitat restoration on the persistence of pollination networks

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    Past and recent studies have focused on the effects of global change drivers such as species invasions on species extinction. However, as we enter the United Nations Decade of Ecosystem Restoration the aim must switch to understanding how invasive-species management affects the persistence of the remaining species in a community. Focusing on plant-pollinator interactions, we test how species persistence is affected by restoration via the removal of invasive plant species. Restoration had a clear positive effect on plant persistence, whereas there was no difference between across treatments for pollinator persistence in the early season, but a clear effect in late season, with higher persistence in unrestored sites. Network structure affected only pollinator persistence, while centrality had a strong positive effect on both plants and pollinators. Our results suggest a hidden effect of invasive plants—although they may compete with native plant species, invasive plants may provide important resources for pollinators, at least in the short term

    Arranjos e relações familiares na velhice: um estudo sobre famílias com idosos no Rio Grande do Sul.

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    O artigo se refere aos resultados de uma pesquisa que identifica o perfil dos arranjos familiares e o papel das trocas não balanceadas nas transições nos arranjos familiares da população idosa de 10 municípios no Rio Grande do Sul. Os dados são oriundos de 2 pesquisas as quais foram um conjunto de dados longitudinais. Aqueles dados são usados para estimar modelos de risco que medem os arranjos de vida características demográficas, estrutura da família e trocas sociais na primeira pesquisa (1995). Especificamente foram usados modelos de risco para identificar transições dentro da família e mortalidade dos idosos entre os anos das duas pesquisas. Os resultados indicam que relações sociais com trocas não balanceadas são parte integral do processo de transição nos arranjos de vida

    Temperature effects on fluorescence quantum efficiency of 9,10-diphenylanthracene

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    The fluorescence quantum efficiency of 9,10-diphenylanthracene in ethanol was measured with very dilute solutions (not more than 5 × 10 -6 M), between 170 and 350 K, relative to solutions at room temperature. The results are compatible with a quantum efficiency of 0.88 at room temperature, which increases to 1.00 for temperatures below 190 K.North Atlantic Treaty Organization (NATO)info:eu-repo/semantics/publishedVersio

    Private umbilical cord blood banks for family use, in Brazil: technical, legal and ethical issues for an implementation analysis

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    Os bancos de sangue de cordão umbilical e placentário foram criados a partir da comprovação de que o sangue de cordão umbilical e placentário (SCUP) é uma fonte rica em células progenitoras hematopoéticas (CPH) e alternativa às células provenientes da medula óssea para transplante, fato que gerou o interesse pelo armazenamento das células nele contidas. A legislação brasileira distingue bancos para uso alogênico não aparentado (públicos) e para uso exclusivamente autólogo (privados). Por sua vez, o armazenamento de SCUP para uso familiar (doação dirigida) pode ser realizado em bancos de sangue de cordão umbilical e placentário públicos, serviços de hemoterapia ou centros de transplante, quando há um membro da família do nascituro com doença diagnosticada e que necessite de transplante de CPH como tratamento. Apesar de a legislação ser clara, a Anvisa tem identificado o interesse sobre a possibilidade da liberação de unidades de SCUP, armazenadas em bancos autólogos, para a utilização de outrem, familiar, além do recém-nascido beneficiário. O objetivo do trabalho visa promover a reflexão sobre uma possível modificação dos parâmetros legais nacionais que regem os bancos de SCUP autólogo, tornando-os bancos com vistas ao uso familiar, por meio da exposição dos principais elementos relacionados ao tema. O estudo analisou os critérios técnico-sanitários legais para regulamentação dos bancos; descreveu as características das CPH de diversas fontes e tipos de doação para transplante; contextualizou a relação com os princípios da Bioética; avanços sobre terapia e pesquisas relativas às CPH; e discutiu possíveis riscos envolvidos no processo.Umbilical cord blood banks have been created worldwide after the discovery that umbilical cord blood (UCB) is a rich source of Hematopoietic Stem Cells (HSC) and an alternative to HSC from bone marrow for allogeneic transplantation. According to Brazilian legislation, banks for allogeneic use (government services) and exclusively autologous use (private services) can be created in the country. The storage of UCB units for direct donation (family use) can occur in public cord blood banks, hemotherapy services and transplant centers when there is a specific need to treat a known patient that is a member of the newborn's family. Even with the legislation being quite clear about the creation of cord blood banks and distribution of UCB units, ANVISA has identified an interest, demonstrated by the population and regulated sector, in the possibility of releasing UCB units, stored in autologous cord blood banks, with the purpose of clinical applicability to another family member other than the newborn owner of the cells. The objective of this study is to promote a discussion on a possible alteration in the legal parameters that support the implementation of autologous cord blood banks, towards the constitution of private banks for family use, pointing out the main issues. The study analyzed the technical and legal criteria related to cord blood banks, described the characteristics of HSC from different sources and types of transplant donations and procedures; discussed concerns related to Bioethical principles, current and potential clinical HSC applications, and possibly risks and benefits

    Temperature and solvent effects on photoluminescence of tryptophan solutions

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    The fluorescence of tryptophan solutions in glycerol, water and ethanol was measured as a function of temperature using steady state and time-resolved techniques. The non-radiative rate constants responsible for the variation of fluorescence quantum yields with temperature are evaluated. Spectral shifts occurring on the nanosecond scale are interpreted in terms of an inversion of 1 L b and 1 L a states produced by solvent perturbation.info:eu-repo/semantics/publishedVersio

    Parthenogenesis and sex-ratio distorting bacteria in Empoasca (Hemiptera: Cicadellidae) Leafhoppers

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    Endosymbiotic bacteria can induce parthenogenesis in many haplo-diploid species, but little is known about their role in asexual reproduction in diplodiploids. Bacteria are essential for reproduction in the asexual lin eages of springtails and booklice, and possibly some weevils, but whether they are the causative agent of par thenogenesis remains to be proven. This would require comparing unisexual forms and their closely related bisexual species, but such model species are very rare. Empoasca leafhoppers from the Madeira Archipelago provide an excellent case to test whether bacterial infections can cause parthenogenesis. Here we examined the diversity of the sex-distorting bacteria, Wolbachia, Cardinium, Rickettsia, and Arsenophonus, in three apo mictic morphotypes (A, B, C) and three bisexual relatives of Empoasca. Wolbachia of group B was present in all unisexual and bisexual species. Rickettsia were the only bacteria restricted to the three unisexual forms, suggesting an association between infection and asexual reproduction. In addition, we found Asaia for the third time in the Cicadellidae, although this may have little to do with the reproductive mode of its host. Adult females of morphotype C reared on plants watered with tetracycline solution did not result in the production of male offspring. To our knowledge, this is the first study to suggest a possible association between bacterial infection and parthenogenesis in apomictic XO/XX diplodiploid bisexual species based on a range of sex ratio distorting bacteria.info:eu-repo/semantics/publishedVersio

    ADAM23 (ADAM metallopeptidase domain 23)

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    Review on ADAM23 (ADAM metallopeptidase domain 23), with data on DNA, on the protein encoded, and where the gene is implicated

    Impact of experimental Nano-HAP pastes on bovine enamel and dentin submitted to a pH cycling model

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    This in vitro study evaluated the preventive potential of experimental pastes containing 10% and 20% hydroxyapatite nanoparticles (Nano-HAP), with or without fluoride, on dental demineralization. Bovine enamel (n=15) and root dentin (n=15) specimens were divided into 9 groups according to their surface hardness: control (without treatment), 20 Nanop paste (20% HAP), 20 Nanop paste plus (20% HAP + 0.2% NaF), 10 Nanop paste (10% HAP), 10 Nanop paste plus (10% HAP + 0.2% NaF), placebo paste (without fluoride and HAP), fluoride paste (0.2% NaF), MI paste (CPP-ACP, casein phosphopeptide-amorphous calcium phosphate), and MI paste plus (CPP-ACP + 0.2% NaF). Both MI pastes were included as commercial control products containing calcium phosphate. The specimens were treated with the pastes twice a day (1 min), before and after demineralization. The specimens were subjected to a pH-cycling model (demineralization–6-8 h/ remineralization-16-18 h a day) for 7 days. The dental subsurface demineralization was analyzed using cross-sectional hardness (kgf/mm 2 , depth 10-220 µm). Data were tested using repeated-measures two-way ANOVA and Bonferroni's test (p<0.05). The only treatment able to reduce the loss of enamel and dentin subsurface hardness was fluoride paste (0.2% NaF), which differed significantly from the control at 30- and 50-µm depth (p<0.0001). The other treatments were not different from each other or compared with the control. The experimental Nanop pastes, regardless of the addition of fluoride, were unable to reduce dental demineralization in vitro
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