6,234 research outputs found
Characterization of Cre recombinase activity for in vivo targeting of adipocyte precursor cells.
The increased incidence of obesity and metabolic disease underscores the importance of elucidating the biology of adipose tissue development. The recent discovery of cell surface markers for prospective identification of adipose precursor cells (APCs) in vivo will greatly facilitate these studies, yet tools for specifically targeting these cells in vivo have not been identified. Here, we survey three transgenic mouse lines, Fabp4-Cre, PdgfRα-Cre, and Prx1-Cre, precisely assessing Cre-mediated recombination in adipose stromal populations and mature tissues. Our data provide key insights into the utility of these tools to modulate gene expression in adipose tissues. In particular, Fabp4-Cre is not effective to target APCs, nor is its activity restricted to these cells. PdgfRα-Cre directs recombination in the vast majority of APCs, but also targets other populations. In contrast, adipose expression of Prx1-Cre is chiefly limited to subcutaneous inguinal APCs, which will be valuable for dissection of APC functions among adipose depots
Diversidade específica da flora pratense à escala do domínio climácico
Em 2005 uma equipa alargada de fitossociólogos portugueses reuniu mais de 1000 inventários fitossociológicos publicados até a data e propôs-se clarificar a composição fitocenótica das séries de vegetação climatófilas e edafoxerófilas portuguesas e explorar a diversidade específica de plantas características das várias etapas sucessionais à escala do domínio climácico, i.e. da área ocupada por uma dada comunidade climácica (vd. Aguiar et al., Floristical and Phytocoenotucal Diversity at the Climactical Dominion, 48th IAVS Symposium, 2005).
Com esse estudo, cujos resultados quedam por publicar, foram estabelecidos critérios objectivos que permitem segregar as comunidades seriais das comunidades próprias de microgeosigmeta e ficou provado o valor heurístico dos padrões espaciais da diversidade específica concretizados à escala do domínio climácico.
No que à vegetação pratense diz respeito as principais conclusões retiradas por aqueles autores foram as seguintes: Em Portugal continental ocorrem 4 tipos de prados seriais: prados anuais, prados vivazes oligotróficos, prados vivazes mesotróficos, prados vivazes de solos incoerentes e prados anuais A continentalidade tem um efeito depressivo na diversidade específica da vegetação pratense Os prados anuais mostram um pico de diversidade específica de espécies características nas áreas mediterrânicas quentes (termomediterrânicas) e oceânicas Nas séries de vegetação mediterrânicas ocorrem dois máximos de diversidade específica nos extremos (em termos de complexidade estrutural) das séries de vegetação, i.e. nos bosques imaturos e nos prados anuais Nos territórios temperados a vegetação herbáceas vivaz mesotrófica é francamente mais diversa do que qualquer outra etapa sucessional Os endemismos são mais frequentes na vegetação herbácea vivaz do que nos prados anuais Os neófitos dominam a vegetação pratense Açoriana e Madeira e dificultam a sua interpretação sindinâmica Aparentemente, a flora pratense indígena é mais diversa nos Açores do que na Madeir
Management of estuarine beaches on the Amazon coast though the application of recreational carrying capacity indices
The purpose of this paper is to determine the Recreational Carrying Capacity of three estuarine beaches (Colares, Marudá and Murubira) on the Amazon coast of Brazil, based on the combined assessment of natural conditions and visitor facilities. In the final analysis, the carrying capacity of Colares beach was estimated to be 1089 visitors per day, and that of Murubira beach, 238 visitors per day. At Marudá beach, however, the inadequate quality of the water resulted in an RCC of zero, indicating that the beach should not be visited for recreational use. The results of this study may provide a valuable diagnostic tool for the development of future state and municipal coastal management programs. We believe that the procedures adopted in this study are applicable to other estuarine beaches on the Amazon coast, as well as in other estuarine beaches elsewhere with similar natural characteristics.Peer ReviewedPostprint (author's final draft
Superconducting Kondo phase in an orbitally-separated bilayer
The nature of superconductivity in heavy-fermion materials is a subject under
intense debate, and controlling this many-body state is central for its
eventual understanding. Here, we examine how proximity effects may change this
phenomenon, by investigating the effects of an additional metallic layer on the
top of a Kondo-lattice, and allowing for pairing in the former. We analyze a
bilayer Kondo Lattice Model with an on-site Hubbard interaction, , on the
additional layer, using a mean-field approach. For , we notice a drastic
change in the density-of-states due to multiple-orbital singlet resonating
combinations. It destroys the well-known Kondo insulator at half filling,
leading to a metallic ground state, which, in turn, enhances antiferromagnetism
through the polarization of the conduction electrons. For , a
superconducting Kondo state sets in at zero temperature, with the occurrence of
unconventional pairing amplitudes involving -electrons. We establish that
this remarkable feature is only possible due to the proximity effects of the
additional layer. At finite temperatures we find that the critical
superconducting temperature, , decreases with the interlayer
hybridization. We have also established that a zero temperature superconducting
amplitude tracks , which reminisces the BCS proportionality between the
superconducting gap and .Comment: 11 pages, 10 figure
Taux d'endemicité et tendances phytogeographiques de la végétation psammophile des plages et des dunes de sable côtier dans le sud-ouest de l'Europe (Portugal continental)
In southwest Europe (mainland Portugal), the psammophilic ecosystems of coastal beaches and sand dunes are distributed by the Eurosiberian (EUR) and
Mediterranean (MED) biogeographic regions. In addition
to climatic and other environmental factors,
distinct plant communities are mainly influenced by
the instability of the coastal sands and the proximity
to the sea. Psammophilic gradients determine the
plant communities that occur from the first sectors
of the beach until the more interior dunes, being
expressed by specific floristic associations and different
rates of cover, namely by endemic taxa. The
analysis of 601 phytosociological relevés, conducted
between 1972 and 2010, from north (Minho) to
the south (Alentejo and Algarve), allowed to study
the dominant communities which occur along the
ecological gradient sea-interior, with the aim of
better understand general spatial geomorphologic
and phytogeographic trends of distribution. As for
the sea-interior gradient, no endemic flora appears
in the first vegetation strip (annual communities of
drift lines). Yet, some endemic species appear in the
embryonic shifting dunes of the back beach, with
endemic species’ coverage of 1.07% (EUR) and 1.7%
(MED). In the mobile dunes (white dunes) covers
by endemic flora are more significant: 6.95% (EUR)
against 4.14% (MED). Semi-stable dune (gray dune),
is composed by three associations (EUR, MED and
another of Transition (ART) which occurs between
the former two), who have the highest covers for
endemics: 38,89% (EUR) 43,37% (TRA) and 55,85%
(MED). Do not considering specific human induced
situations of degradation and erosion, a general
trend of gradual coverage growth by endemic
taxa, was signed from north to south, despite median
overall covers (total species) are higher in the
north. The endemic taxa have been separated into
endemic Portuguese (EP), Iberian (EI) and European
(EU) and its representativeness endorsed. The interest
in the use of phytosociology in this kind of study is discusse
Sobre as comunidades de Pterospartum tridentatum sensu lato em Portugal continental
FRANCO (1971) aquando da publicação da Nova Flora de Portugal só considerou ocorrer no território nacional Pterospartum tridentatum (L.) Willk., sob o nome de Chamaespartium tridentatum (L.) P. Gibbs, contudo TALAVERA (1999), na Flora Ibérica, considerou que esta espécie era constituída por três subespécies: Pterospartum tridentatum subsp. tridentatum, Pterospartum tridentatum subsp. cantabricum (Spach) Talavera & P. Gibbs, Pterospartum tridentatum subsp. lasianthum (Spach) Talavera & P. Gibbs, que posteriormente RIVAS-MARTÍNEZ et al. (2002) reputaram serem espécies independentes. Com esta nota pretendemos esclarecer as comunidades em que estes táxones desempenham um papel importante em Portugal continental
The meaning of mainland Portugal beaches and dunes' psammophilic plant communities: a contribution to tourism management and nature conservation
Due to their position of interface between the sea
and land, the flora and vegetation of coastal beaches and
dunes, occupy ecologically extreme, sensitive, unique and
valuable habitats. The occurrence of a large number of
endemic taxa and specific plant associations endowed with
key ecological services and adapted to a stressful and harsh
environmental gradient, gives them a high interest for nature
conservation and an important role in sustainable territorial
planning. However, such ecosystems are vulnerable to the
disruption caused by several anthropogenic sources. Among
other global threat factors, the inevitable sea rise caused by
climate change and, at a local scale, the non-negligible
implications of trampling caused by disorderly coastal touristic
exploitation, growing construction pressure in the littoral,
and a seasonal population boom in late spring and in
summer, plus all derivate forms of pollution, are threat
factors to their integrity. Therefore, a correct planning of
the touristic economic activities requires the understanding
of the vegetation composition and spatial distribution patterns,
intrinsically determined by their biogeographic context
in the Euro-Siberian or Mediterranean Regions. This
comprehensive work, based on a broad phytogeographic study, brings together disperse information on plant communities
of the Portuguese sandy coasts (beaches and
dunes), by analysing floristic compositions, chorology and
ecological characteristics, and matching them with the “Nature
2000” network habitats. Resilience and vulnerability
are also studied. In a nature conservation perspective, a
positive balance (and a sustainable co-existence) between
the preservation of natural values and human development
in the Portuguese coast, will benefit with the integration of
this knowledge in coastal planning and management
activitie
Bioindicators of erosive dynamics in beach and dune systems in the portuguese mainland coast
The litoral psammophilic ecosystems are organized according gradients leaning from the sea to interior
areas, including a succession of phytosociological associations,
correspondent to well discriminate biotopes,
according their geomorphologic, soil and ecological
characteristics. In the stable sandy shores (in terms of
erosion balance), the different communities occupy
relatively wide zonal tracks, with clear transitions. However,
in situations of beach downwasting and coastline
retreat, the mobile sands tend to advance inland, often
compressing the zonal gradient, and distinct communities
tend to overlap. Since the herbaceous hemicryptophitic
flora typical from the beach and instable dunes
has intrinsic colonization skills, high tolerance (or even
preference) to burial, and elevated growing rates, it can
quickly adapt to the instability of the topographic surface,
accompanying its movement to the interior. Yet,
the growing rates of the woody chamaephitic vegetation,
characteristic of the more interior and relatively
stable dune (gray dune) are slower, in addition to a lower
capability to resist to burial. Thus, sea advance and
inherent sands mobility inland, combined with the dissimilar
resilience of plant associations, results in the in
the overlap of the chamaephitic taxa and in the amalgamation
of species from different communities. The main
objective of this work was to study general trends of
erosion along the Portuguese softline mainland coast,
based in the analysis of the dominant associations that
occur along the psammophilic gradient. It was focused
in the role played by some plants has bioindicators
of the velocity of erosional processes caused by wind
transportation, sea dynamics and coastal retreat. Plants
that can be used has reliable bioindicators are identified.
Correlations between the observed alterations in
the theoretical model of a coastal psammophilic gradient,
and the intensity of erosion are established. The intensity
of the phenomenon is analyzed and quantified
along different sectors of the Portuguese coast
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