223 resultados para Eph
Resumo:
Pollen analysis of Wisconsinan sediments from eleven localities in northern and central Illinois, combined with the results of older studies, allows a first general survey of the vegetational changes in Illinois during the last glaciation. In the late Altonian (after 40,000 B.P.), pine was already the most prevalent tree type in northern Illinois. Probably because of the influence of the last Altonian ice advance to northern Illinois, pine migrated to the south and reached south-central Illinois, which was at that time a region of prairie, with oak and hickory trees in favorable sites. Likewise in the late Altonian, spruce appeared in northern Illinois. Spruce also expanded its area to the south during the Wisconsinan, reaching south-central Illinois only after 21,000 B.P., in the early Woodfordian. Deciduous trees (predominantly oak) were present in south-central Illinois throughout the Wisconsinan. Their prevalence decreased to the north. The vegetation during the different subdivisions of the last glacial period in Illinois was approximately as follows: Late Altonian: Pine/spruce forest with some deciduous trees in northern and central Illinois; prairie and oak/hickory stands in south-central Illinois; immigration of pine. Farmdalian: Pine/spruce forest in central Illinois; deciduous trees and pine in south-central Illinois, with areas of open vegetation, perhaps similar to the present-day transition of prairie to forest in the northern Great Plains. Woodfordian: Northern and central Illinois ice covered; in south central Illinois, spruce and oak as dominant tree types, but also pine and grassland. During the Woodfordian, pine and spruce disappeared again from south-central Illinois, and oak/hickory forest and prairie again prevailed. The ice-free areas of northern Illinois become populated temporarily with spruce, but later there is proof of deciduous forest in this region. Pollen investigations in south-central Illinois have shown convincingly that deciduous trees could survive relatively close (less than 60 km) to the ice margin. Therefore the frequently presented view that arctic climatic conditions prevailed in North America during the last glaciation far south of the ice margin can be refuted for the Illinois area, confirming the opinion of other authors resulting from investigations of fossil mollusks and frost-soil features. The small number of localities investigated still permits no complete reconstruction of the vegetation zones and their possible movements in Illinois. During the Altonian and Farmdalian in Illinois, a vegetational zonation probably existed similar to that of today in North America. As the ice pushed southward as far as 39° 20' N. lat in the early Woodfordian, this zonation was apparently broken up under the influence of a relatively moderate climate. In any case, the Vandalia area, which was only about 60 km south of the ice, was at that time neither in a tundra zone nor in a zone of boreal coniferous forest.
Resumo:
Sporomorphs and dinoflagellate cysts from site GIK16867 in the northern Angola Basin record the vegetation history of the West African forest during the last 700 ka in relation to changes in salinity and productivity of the eastern Gulf of Guinea. During most cool and cold periods, the Afromontane forest, rather than the open grass-rich dry forest, expanded to lower altitudes partly replacing the lowland rain forest of the borderlands east of the Gulf of Guinea. Except in Stage 3, when oceanic productivity was high during a period of decreased atmospheric circulation, high oceanic productivity is correlated to strong winds. The response of marine productivity in the course of a climatic cycle, however, is earlier than that of wind vigour and makes wind-stress-induced oceanic upwelling in the area less likely. Monsoon variation is well illustrated by the pollen record of increased lowland rain forest that is paired to the dinoflagellate cyst record of decreased salinity forced by increased precipitation and run-off.
Resumo:
Fluxes of airborne freshwater diatoms (FD), phytoliths (PH), and pollen grains (PO) collected with sediment traps off Cape Blanc, northwest Africa, from 1988 till 1991 are presented. Both continental rainfall variations and wind mean strength and direction play a key role in the temporal fluctuations of the fluxes of eolian traces in the pelagic realm. Drier conditions in Northern Africa in 1987 could have preceded the high lithogenic input and moderate FD flux in 1988. The PH peak in summer 1988 was probably caused by increased wind velocity. Wetter rainy seasons of 1988/89 might have promoted a significant pollen production in summer 1989, and FD in late 1989 and early 1990, as well as contributed to the reduction of the lithogenic flux in 1989/90. Decreased fluxes of FD, PH and PO, and higher contribution of the 6-11 µm lithogenic fraction in 1991 would mainly reflect minor intensity and decreased amount of continental trade winds. Air-mass backward trajectories confirm that the Saharan Air Layer is predominantly involved in the spring/summer transport. Trade winds play a decisive role in the fall/winter months, but also contribute to the transport during late spring/summer. Origin of wind trajectories does not support a direct relationship between transporting wind-layers and material source areas in Northern Africa. High winter fluxes of eolian tracers and high amount of trade winds with continental origin in summer warn against a simplistic interpretation of the seasonal eolian signal preserved in the sediments off Cape Blanc, and the wind layer involved in its transport.
Resumo:
Influx of aeolian pollen trapped in marine sediments off Namibia provides a wind variation record for the last 135 kyr. The influx of major pollen components is derived from the southwest African desert/semi-desert zone and shows six periods during which enhanced southeast trade winds contributed to strong upwelling and reduced sea surface temperatures. The most prominent of these occurred during 17-23 cal. kyr, 42-56 kyr and before 130 kyr B.P. Correspondence between the pollen influx record and the Vostok deuterium isotope record suggests that pronounced glacial Antarctic cooling was accompanied by intensification of the southeast trades throughout the Late Quaternary. However, during 42-23 kyr B.P. the combination of strong Antarctic glaciation with a decrease of wind zonality induced by low latitude precessional insolation changes caused strong alongshore winds and Ekman pumping that resulted in strong upwelling and reduced sea surface temperatures without pollen influx enhancement.
Resumo:
To better understand Holocene vegetation and hydrological changes in South Africa, we analyzed pollen and microcharcoal records of two marine sites GeoB8331 and GeoB8323 from the Namaqualand mudbelt offshore the west coast of South Africa covering the last 9900 and 2200 years, respectively. Our data corroborate findings from literature that climate developments apparently contrast between the summer rainfall zone (SRZ) and winter rainfall zone (WRZ) over the last 9900 years, especially during the early and middle Holocene. During the early Holocene (9900-7800 cal.yr BP), a minimum of grass pollen suggests low summer rainfall in the SRZ, and the initial presence of Renosterveld vegetation indicates relatively wet conditions in the WRZ. Towards the middle Holocene (7800-2400 cal. yr BP), a rather moist savanna/grassland rich in grasses suggests higher summer rainfall in the SRZ resulting from increased austral summer insolation and a decline of fynbos vegetation accompanied by an increasing Succulent Karoo vegetation in the WRZ possibly suggests a southward shift of the Southern Hemisphere westerlies. During the last 2200 years, a trend towards higher aridity was observed for the SRZ, while the climate in the WRZ remained relatively stable. The Little Ice Age (ca. 700-200 cal. yr BP) was rather cool in both rainfall zones and drier in the SRZ while wetter in the WRZ.
Resumo:
A functional nervous system requires the precise arrangement of all nerve cells and their neurites. To achieve this correct assembly, a myriad of molecular guidance cues works together to direct the outgrowth of neurites to their correct positions. The small nematode C. elegans provides the ideal model system to study the complex mechanisms of neurite guidance due to its relatively simple nervous system, composed of 302 neurons. I used two mechanosensory neurons, called the posterior lateral microtubule (PLM), to investigate the role of the ephrin and Eph receptor protein family in neurite termination in C. elegans. Activation of the C. elegans Eph receptor VAB-1 on the PLM growth cone is sufficient to cause PLM termination, but the identity and location of the activating ligand has not been established. In my thesis I investigated the ability of the ephrin ligand EFN-1 to activate VAB-1 to cause PLM termination when expressed on the same cell (in cis) and on opposing cells (in trans) to the receptor. I showed that EFN-1 is able to activate VAB-1 in cis and in trans to cause PLM termination. I also assessed the hypodermal seam cells as the source of the ephrin stop cue using fluorescently labelled and seam cell mutant transgenic worms. I found that although the PLM shows consistent termination on the seam cell V2 in wild type worms independent of PLM length, this process is not significantly disrupted in seam cell mutants. With this information I have created a new hypothesis that the PLM neurite is able the provide a positional cue for the developing seam cells, and have created a new transgenic strain which can be used to assess the impact of PLM and ALM cell ablation on seam cell position. My research is the first to demonstrate the ability of an ephrin ligand to activate its ephrin receptor in cis, and further research can investigate if this finding has in vivo applications.
Resumo:
El trabajo postula que si bien las políticas desarrolladas en la actual fase de crecimiento han favorecido la ampliación de la demanda de empleo, este proceso no evidencia -al menos todavía- un cambio cualitativo en lo que refiere a una disminución de la heterogeneidad socio-productiva. En este sentido, se sostiene que continuaría vigente la segmentación de los mercados laborales y una alta concentración de recursos -incluida la fuerza de trabajo con mejores credenciales educativas- sobre los sectores más dinámicos del sistema económico. La información utilizada surge de los microdatos de la Encuesta Permanente de Hogares del INDEC (EPH-Continua), y corresponden al total urbano relevado por dicha encuesta para los años testigo considerados en el estudio (2004, 2007 y 2011)
Resumo:
As argamassas mistas de cal e terra devem ter resultado da prática profissional quando as condições económicas foram possibilitando a adição de cais aérea às argamassas vernaculares só de terra. Baixas adições de cal aérea a argamassas de terra têm conduzido a drásticas alterações da cor e das resistências mecânicas das argamassas de terra. No entanto, a substituição parcial de massa de cal por terra em argamassas de cal ao traço volumétrico 1:2 (correspondendo a argamassas com traço em massa de 1:8, com substituições de 10% a 50%) resulta em argamassas mais ecológicas e que tecnicamente indiciam ser adequadas para aplicação em rebocos de edifícios antigos e mesmo em construção nova com características compatíveis. Os resultados obtidos foram particularmente interessantes para uma substituição de 10% mas muito há ainda a fazer para um conhecimento aprofundado deste tipo de argamassas mistas de cal e terra, muito utilizadas no passado, com vista à otimização de formulações que possam vir a ser aplicadas correntemente.
Resumo:
La Computación Efímera (Eph-C , por sus siglas en inglés, Ephemerical Computing) es un nuevo paradigma de computación de reciente creación que pretende sacar provecho de la naturaleza pasajera (o sea, asociada a un tiempo de vida limitado) de los recursos computacionales. En este trabajo se introducirá este nuevo paradigma Eph-C de forma general, y se irá poco a poco enfocando específicamente dentro del contexto del proceso de desarrollo de videojuegos, mostrando posibles aplicaciones y beneficios dentro de las principales líneas de investigación asociadas a la creación de los mismos. Se trata de un trabajo preliminar que intenta indagar en las posibilidades de aplicar la computación efímera en la creación de productos en la industria del videojuego. Lo que presentamos aquí debe ser valorado como un trabajo preliminar que intenta a su vez servir de inspiración para otros posibles investigadores o desarrolladores de videojuegos.
Resumo:
Ephemeral Computation (Eph-C) is a newly created computation paradigm, the purpose of which is to take advantage of the ephemeral nature (limited lifetime) of computational resources. First we speak of this new paradigm in general terms, then more specifically in terms of videogame development. We present possible applications and benefits for the main research fields associated with videogame development. This is a preliminary work which aims to investigate the possibilities of applying ephemeral computation to the products of the videogame industry. Therefore, as a preliminary work, it attempts to serve as the inspiration for other researchers or videogame developers.
Resumo:
Abstract This communication reflects the work done in the Department of Civil Engineering and Architecture at the University of Beira Interior (Portugal), and still ongoing, in the framework of the project ORFEUS - The Tridentine Reform and music in the cloistral silence: the Monastery of S. Bento de Cástris (Project FCT EXPL/EPH-PAT/2253/2013) and aims to bring the debate to a contribution to the study of the specificity of the monastery of St. Bento de Cástris in the context of Cistercian architecture, in which the shape and the music are intertwined. In this way, two dissertations have been developed in Architecture (integrated master course of architecture of the University of Beira Interior) within the project ORFEUS, which are divided by the importance and contributions of the Cistercian Architecture in contemporary religious architecture, the morphology of the Cistercian churches and the relationship between architecture and music in the specific case study of the church of the monastery of St. Bento de Cástris. Resumo Esta comunicação reflecte o trabalho desenvolvido no Departamento de Engenharia Civil e Arquitectura da Universidade da Beira Interior, e ainda em curso, no âmbito do Projecto ORFEUS - A Reforma tridentina e a música no silêncio claustral: o mosteiro de S. Bento de Cástris (Projecto FCT EXPL/EPH- PAT/2253/2013) e pretende-se com esta comunicação trazer a debate um contributo para o estudo da especificidade do Mosteiro de S. Bento de Cástris, no contexto da arquitectura cisterciense, no qual a forma e a música se entrelaçam. Neste sentido foram desenvolvidas duas dissertações de mestrado integrado em Arquitectura, no âmbito do Projecto ORFEUS, que se repartem pela importância e contributos da Arquitectura Cisterciense na Arquitectura religiosa contemporânea, a morfologia das igrejas cistercienses e a relação entre a arquitectura e música patente no estudo de caso da igreja do Mosteiro de S. Bento de Cástris.
Resumo:
MEGAGEO - Moving megaliths in the Neolithic is a project that intends to find the provenience of lithic materials in the construction of tombs. A multidisciplinary approach is carried out, with researchers from several of the knowledge fields involved. This work presents a spatial data warehouse specially developed for this project that comprises information from national archaeological databases, geographic and geological information and new geochemical and petrographic data obtained during the project. The use of the spatial data warehouse proved to be essential in the data analysis phase of the project. The Redondo Area is presented as a case study for the application of the spatial data warehouse to analyze the relations between geochemistry, geology and the tombs in this area.
Resumo:
Despite extensive research and introduction of innovative therapy, lung cancer prognosis remains poor, with a five years survival of only 17%. The success of pharmacological treatment is often impaired by drug resistance. Thus, the characterization of response mechanisms to anti-cancer compounds and of the molecular mechanisms supporting lung cancer aggressiveness are crucial for patient’s management. In the first part of this thesis, we characterized the molecular mechanism behind resistance of lung cancer cells to the Inhibitors of the Bromodomain and Extraterminal domain containing Proteins (BETi). Through a CRISPR/Cas9 screening we identified three Hippo Pathway members, LATS2, TAOK1 and NF2 as genes implicated in susceptibility to BETi. These genes confer sensitivity to BETi inhibiting TAZ activity. Conversely, TAZ overexpression increases resistance to BETi. We also displayed that BETi downregulate both YAP, TAZ and TEADs expression in several cancer cell lines, implying a novel BETi-dependent cytotoxic mechanism. In the second part of this work, we attempted to characterize the crosstalk between the TAZ gene and its cognate antisense long-non coding RNA (lncRNA) TAZ-AS202 in lung tumorigenesis. As for TAZ downregulation, TAZ-AS202 silencing impairs NSCLC cells proliferation, migration and invasion, suggesting a pro-tumorigenic function for this lncRNA during lung tumorigenesis. TAZ-AS202 regulates TAZ target genes without altering TAZ expression or localization. This finding implies an uncovered functional cooperation between TAZ and TAZ-AS202. Moreover, we found that the EPH-ephrin signaling receptor EPHB2 is a downstream effector affected by both TAZ and TAZ-AS202 silencing. EPHB2 downregulation significantly attenuates cells proliferation, migration and invasion, suggesting that, at least in part, TAZ-AS202 and TAZ pro-oncogenic activity depends on EPH-ephrin signaling final deregulation. Finally, we started to dissect the mechanism underlying the TAZ-AS202 regulatory activity on EPHB2 in lung cancer, which may involve the existence of an intermediate transcription factor and is the object of our ongoing research.