362 research outputs found
A floresta aberta com bambu no sudoeste da Amazônia : padrões e processos em múltiplas escalas
Get PDFTese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, 2001.Florestas ombrófilas abertas com bambus arborescentes e espinhosos do gênero Guadua, cobrem cerca de 180.000 km2 ' do sudoeste da Amazônia e são facilmente identificadas através de imagens do satélite Landsat. Além de semelparas e monocárpicas, estas espécies de bambu possuem incrível habilidade de crescimento horizontal através de rizomas, crescimento vertical extremamente rápido e hábito semiescandente. Guadua weberbaueri tem um ciclo de vida que varia de 29 à 32 anos e distribuição ampla na região. A amplitude de distribuição e o caráter dominante desses bambus determinam padrões estruturais tanto das comunidades ecológicas quanto da paisagem. Estes padrões são a resultante de mecanismos e processos que ocorrem nas escalas populacional e organísmica (individual). Este estudo objetivou: i) identificar as relações entre as diferentes escalas ecológicas na determinação dos padrões e dos processos que expliquem a distribuição das florestas com bambu no Estado do Acre; ii) na escala individual, investigar a estrutura dos rizomas, a estratégia de crescimento clonal e a alocação de biomassa de Guadua weberbaueri; iii) na escala populacional, calcular as taxas de crescimento, recrutamento e mortalidade de colmos de G. weberbaueri; iv) na escala de comunidade, analisar os efeitos de G. weberbaueri sobre a estrutura e a dinâmica da floresta; v) na escala de paisagem, identificar os padrões temporais e espaciais da floresta com bambu; v) desenvolver um modelo ecológico conceituai que integre as informações geradas nas diferentes escalas. Na escala individual, há evidências de integração fisiológica entre os módulos, e a forma de crescimento clonal, combina as estratégias guerrilheira e lalangeal; estes são os mecanismos de compartilhamento de recursos, de forageamento e captura de espaço, que afetam a capacidade competitiva de G. weberbaueri. O crescimento dos colmos sofre forte influência da sazonal idade, especialmente durante a estação chuvosa. O incremento médio na altura total foi 3,4 m/mês. A média da taxa de recrutamento e de mortalidade de colmos para o período de 1996-2000, foi de 21% e 14%, respectivamente. É provável que as variações climáticas observadas no período tenham sido promovidas pelos fenômenos El Nino e La Nina. Guadua weberbaueri afeta a estrutura da comunidade florestal, reduzindo a densidade de árvores e a área basal da floresta, e diminuindo de 30 à 50% o potencial de armazenamento de carbono. O bambu também altera a composição florística, reduzindo em quase 40% o número de espécies em uma amostra de um hectare. A riqueza resultante é uma das menores da Amazônia. A ação seletiva do bambu favorece o crescimento de espécies características dos estágios iniciais da sucessão ecológica, cujo ciclo de vida curto em implicações diretas sobre a dinâmica da floresta. A taxa de mortalidade anual (3,4%) e o turnover (29 anos), permitem caracterizar essa floresta como uma das mais dinâmicas da Amazônia. Na escala de paisagem, bordas nítidas foram observadas entre a floresta com bambu ocorrendo em terreno colinoso e solo argiloso da Depressão Rio Acre-Javari e a floresta sem bambu no terreno dissecado e solo arenoso no Planalto Rebaixado da Amazônia Ocidental, onde o bambu inexiste. Bordas arredondadas identificadas entre a floresta com bambu e a floresta sem bambu sugerem que a expansão ou está em curso ou que foi mediada por fogo pretérito. Internamente a floresta com bambu apresenta dois tipos de borda. Bordas temporais nítidas, que ocorrem quando distintas populações de Guadua apresentam assincronia no florescimento e mortalidade, e bordas difusas, foram relacionadas com a variação na densidade do bambu ao longo da topossequência (mais densos nas vertentes e fundos de vale). As relações entre os padrões e processos estudados foram exploradas a partir da integração do conhecimento ecológico nas múltiplas escalas, através do desenvolvimento de um modelo ecológico descritivo. Este modelo explora como os mecanismos biológicos que ocorrem em escalas mais finas, podem assinalar padrões detectados em grande escala.Open forests with arborescent and thorny bamboos of the genus Guadua, covers about 180,000 km2 of the Southwestern Amazonia and are easily identified through Landsat satellite images. Guadua species are semelparous and monocarpic, grow horizontally through rhizomes, and have a fast growth and climbing habit. Guadua weberbaueri has a 29-32-year life-cycle and has a widespread distribution in the region. Bamboo distribution and dominance are determinants of both community and landscape patterns. These patterns are the result of mechanisms and processes that occur at the population and organismic (individual) scales. The aim of this study was: i) to identify the relationships between patterns and processes that explain the bamboo-forest distribution in Acre State; ii) at the individual scale, to investigate the structure of rhizomes, the clonal growth strategy, and biomass alocation in Guadua weberbaueri', iii) at the population scale, to record growth, recruitment and mortality of G. weberbaueri culms; iv) at the community scale, to analyze the effects of G. weberbaueri on the structure and dynamics of the forest; v) at the landscape scale, to identify spatial and temporal modifications in bamboo-forest; vi) finally to develop a conceptual ecological model that integrates information generated in the diferent scales. At the individual scale, there arc evidence of physiological integration between ramcis; clonal growth form combines both guerrilla and phalanx strategies; these are the mechanisms G. weberbaueri uses for foraging for resources for spatial occupation; both affect the competitive ability of the species. Culm growth is affected by climate seasonality, particularly during the rainy season. The average increment in height was 3.4 meters per month. The rate of culm recruitment and mortality during the 1996-2000 period, was 21% and 14%, respectively. Possibly the observed variation was promoted by the Eil Nino and La Nina phenomena. Giuidua weberbaueri affects community structure, reducing tree density and the basal area of the forest, and by decreasing the carbon storage potencial by 30-50%. The bamboo alters the floristic composition, reducing the number of species in a one hectare plot by almost 40%. The resulting richness is one of the smallest reported for the Amazon. The bamboo also favors the growth of early successional trees, whose short life cycle may have direct effects on the forest dynamics. The annual tree mortality rate (3.4%) and turnover time (29 years), make this as one of the most dynamic forests in the Amazon. At the landscape scale, quite distinctive borders were observed between forest with bamboos occuring in slope terrains and loamy soil of the Rio Acre-Javari depression; on the other hand the forest without bamboos occur in the dissected land and sandy soils of the Planalto Rcbaixado da Amazonia Ocidental. Round borders identified in the images suggest either ongoing expansion or expansion that was mediated by fire. Inside the forest with bamboo two border types are identified: a distinctively “temporal border” that occurs when different Guadua‘s populations present asynchronous mass flowering and mortality; and diffuse borders, which is related to differences in bamboo density along the catena (denser in the slopes and valleys). The relationship between the observed patterns and mechanisms (processes) studied were explored in a conceptual model that integrates the multiple ecological scales. The model explores how the biological mechanisms at finer scales can affect patterns detected at broader scales.Instituto de Ciências Biológicas (IB)Programa de Pós-Graduação em Ecologi
Music made visible in time and space : concepts of simultaneity in tone-eurythmy choreography
No full textIncludes bibliographical references (leaves 105-113).Eurythmy is an art of movement that expresses music and speech. This dissertation explores eurythmy's musical field, called tone-eurythmy, in its multifaceted appearances, background and within its philosophical context. Tone-eurythmy, carried out by performers moving in space and time, makes music visible. It transforms music into a new movement-art form, that of audible-visible music, by expressing musical components as well as the artistic intentions within a composition and those held by the performing artists. The dissertation examines how musical concepts are seen by eurythmists to integrate ideas of wholeness and to understand music as both audible and inaudible. It draws on studies and findings from music psychology to show distinct effects of musical elements on the human being, and to indicate the similarities between those and the qualitative expressions of music through tone-eurythmy
Draft Genome Sequence of an Escherichia coli O157:H43 Strain Isolated from Cattle
No full textHere we report the draft genome sequence of an Escherichia coli O157:H43 strain, designated T22, with an atypical virulence gene profile and isolated from healthy cattle. T22 produces cytolethal distending toxin V (CDT-V) and belongs to phylogenetic group B1 and sequence type 155 (ST155)
Controlling distinct signaling states in cultured cancer cells provides a new platform for drug discovery
No full textCancer cells can switch between signaling pathways to regulate growth under different conditions. In the tumor microenvironment, this likely helps them evade therapies that target specific pathways. We must identify all possible states and utilize them in drug screening programs. One such state is characterized by expression of the transcription factor Hairy and Enhancer of Split 3 () and sensitivity to knockdown, and it can be modeled . Here, we cultured 3 primary human brain cancer cell lines under 3 different culture conditions that maintain low, medium, and high expression and characterized gene regulation and mechanical phenotype in these states. We assessed gene expression regulation following knockdown in the -high conditions. We then employed a commonly used human brain tumor cell line to screen Food and Drug Administration (FDA)-approved compounds that specifically target the -high state. We report that cells from multiple patients behave similarly when placed under distinct culture conditions. We identified 37 FDA-approved compounds that specifically kill cancer cells in the high--expression conditions. Our work reveals a novel signaling state in cancer, biomarkers, a strategy to identify treatments against it, and a set of putative drugs for potential repurposing.-Poser, S. W., Otto, O., Arps-Forker, C., Ge, Y., Herbig, M., Andree, C., Gruetzmann, K., Adasme, M. F., Stodolak, S., Nikolakopoulou, P., Park, D. M., Mcintyre, A., Lesche, M., Dahl, A., Lennig, P., Bornstein, S. R., Schroeck, E., Klink, B., Leker, R. R., Bickle, M., Chrousos, G. P., Schroeder, M., Cannistraci, C. V., Guck, J., Androutsellis-Theotokis, A. Controlling distinct signaling states in cultured cancer cells provides a new platform for drug discovery
Mixed mode oscillations in mouse spinal motoneurons arise from a low excitability state
Get PDFWe explain the mechanism that elicits the mixed mode oscillations (MMOs) and the subprimary firing range that we recently discovered in mouse spinal motoneurons. In this firing regime, high-frequency subthreshold oscillations appear a few millivolts below the spike voltage threshold and precede the firing of a full blown spike. By combining intracellular recordings in vivo (including dynamic clamp experiments) in mouse spinal motoneurons and modeling, we show that the subthreshold oscillations are due to the spike currents and that MMOs appear each time the membrane is in a low excitability state. Slow kinetic processes largely contribute to this low excitability. The clockwise hysteresis in the I–F relationship, frequently observed in mouse motoneurons, is mainly due to a substantial slow inactivation of the sodium current. As a consequence, less sodium current is available for spiking. This explains why a large subprimary range with numerous oscillations is present in motoneurons displaying a clockwise hysteresis. In motoneurons whose I–F curve exhibits a counterclockwise hysteresis, it is likely that the slow inactivation operates on a shorter time scale and is substantially reduced by the de-inactivating effect of the afterhyperpolarization (AHP) current, thus resulting in a more excitable state. This accounts for the short subprimary firing range with only a few MMOs seen in these motoneurons. Our study reveals a new role for the AHP current that sets the membrane excitability level by counteracting the slow inactivation of the sodium current and allows or precludes the appearance of MMOs
Controlling distinct signaling states in cultured cancer cells provides a new platform for drug discovery
No full textCancer cells can switch between signaling pathways to regulate growth under different conditions. In the tumor microenvironment, this likely helps them evade therapies that target specific pathways. We must identify all possible states and utilize them in drug screening programs. One such state is characterized by expression of the transcription factor Hairy and Enhancer of Split 3 (HES3) and sensitivity to HES3 knockdown, and it can be modeled in vitro. Here, we cultured 3 primary human brain cancer cell lines under 3 different culture conditions that maintain low, medium, and high HES3 expression and characterized gene regulation and mechanical phenotype in these states. We assessed gene expression regulation following HES3 knockdown in the HES3-high conditions. We then employed a commonly used human brain tumor cell line to screen Food and Drug Administration (FDA)-approved compounds that specifically target the HES3-high state. We report that cells from multiple patients behave similarly when placed under distinct culture conditions. We identified 37 FDA-approved compounds that specifically kill cancer cells in the high-HES3–expression conditions. Our work reveals a novel signaling state in cancer, biomarkers, a strategy to identify treatments against it, and a set of putative drugs for potential repurposing.—Poser, S. W., Otto, O., Arps-Forker, C., Ge, Y., Herbig, M., Andree, C., Gruetzmann, K., Adasme, M. F., Stodolak, S., Nikolakopoulou, P., Park, D. M., Mcintyre, A., Lesche, M., Dahl, A., Lennig, P., Bornstein, S. R., Schroeck, E., Klink, B., Leker, R. R., Bickle, M., Chrousos, G. P., Schroeder, M., Cannistraci, C. V., Guck, J., Androutsellis-Theotokis, A. Controlling distinct signaling states in cultured cancer cells provides a new platform for drug discovery. FASEB J. 33, 9235–9249 (2019). www.fasebj.org. © FASE
Microfluidic solvent extraction of copper from malachite-chalcopyrite mineral leach solution
Get PDFMicrofluidics is concerned with the characteristics and manipulation of fluid flows along mili- and micro-sized channels at very low Reynolds numbers intended for specific applications. It affords improvements based on several factors such as enhanced surface area-to-volume ratio and faster diffusion which facilitate efficient extractions and phase separations. In this study, microfluidic solvent extraction (μSX) was investigated as an alternative to conventional bulk solvent extraction of copper from a mineral leach solution. While bulk extraction typically requires a two-step mixer-settler stage, μSX precludes the need of a settler. A copper solution was produced by using sulfuric acid as leachant of a composite malachite–chalcopyrite ore. A microfluidic Y-Y channel placed on the format of a microscopy polymethylmethacrylate (PMMA) slide was used for the μSX process. LIX84 (10% v/v) dissolved in Shellsol was used as the extractant. In a typical μSX application, two streams (one is the copper leach solution and the other is the extractant) are in direct parallel contact along the microsized channel. There was no observable blockage along the microfluidic channel and copper extraction was accomplished under continuous phase flow
An Integrated 13.56-MHz RFID Tag in a Printed Organic Complementary TFT Technology on Flexible Substrate
No full textS.1668-1677This paper presents the first printed organic 13-MHz RFID on flexible substrate. The proposed solution includes a planar near field antenna bonded to an RFID tag, which is printed on flexible foil using an organic complementary TFT technology. Thanks to an active envelope detector, ASK modulation with modulation depth as low as 20% can be adopted to increase the available input power for the rectifier. The RFID functionality is demonstrated at the internally generated supply voltage of 24 V, for a reading range of 2-5 cm and a bit-rate up to 50 bit/s. With more than 250 transistors on the same foil, this work represents the most complex circuit ever published in a printed organic complementary TFT technology.62Nr.
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