Search results for "Category"
showing 10 items of 4660 documents
Generalized twisted cubics on a cubic fourfold as a moduli space of stable objects
2016
We revisit the work of Lehn-Lehn-Sorger-van Straten on twisted cubic curves in a cubic fourfold not containing a plane in terms of moduli spaces. We show that the blow-up $Z'$ along the cubic of the irreducible holomorphic symplectic eightfold $Z$, described by the four authors, is isomorphic to an irreducible component of a moduli space of Gieseker stable torsion sheaves or rank three torsion free sheaves. For a very general such cubic fourfold, we show that $Z$ is isomorphic to a connected component of a moduli space of tilt-stable objects in the derived category and to a moduli space of Bridgeland stable objects in the Kuznetsov component. Moreover, the contraction between $Z'$ and $Z$ i…
Separation properties of continuous maps in codimension 1 and geometrical applications
1992
Abstract Nuno Ballesteros, J.J. and M.C. Romero Fuster, Separation properties of continuous maps in codimension 1 and geometrical applications, Topology and its Applications 46 (1992) 107-111. We show that the image of a proper closed continuous map, f , from an n -manifold X to an ( n + 1)-manifold Y , such that H 1 (Y; Z 2 ) =0 , separates Y into at least two connected components provided the self-intersections set of f is not dense in any connected component of Y . We also obtain some geometrical applications.
On fuzzification of topological categories
2014
This paper shows that (L,M)-fuzzy topology of U. Hohle, T. Kubiak and A. Sostak is an instance of a general fuzzification procedure for topological categories, which amounts to the construction of a new topological category from a given one. This fuzzification procedure motivates a partial dualization of the machinery of tower extension of topological constructs of D. Zhang, thereby providing the procedure of tower extension of topological categories. With the help of this dualization, we arrive at the meta-mathematical result that the concept of (L,M)-fuzzy topology and the notion of approach space of R. Lowen are ''dual'' to each other.
The Origin of Isolated Populations of the Mountain Weevil, Liparus glabrirostris—The Flagship Species for Riparian Habitats
2020
AbstractLiparus glabrirostris is one of the largest European weevils, and it has been recently proposed as the flagship species for threatened riparian habitats in the mountains. For effective conservation of its populations (and associated habitats), it is crucial to understand its history, contemporary distribution, genetic diversity and predict changes in the range, including its highly isolated populations on the Baltic coast. Here, we examined numerous populations of L. glabrirostris across almost the entire species range using phylogeography and species niche modeling (SNM) approaches. Analyses of mtDNA and nucDNA markers revealed the existence of 2 major mitochondrial lineages genera…
Conservation genetics of insular **Podarcis** lizards using partial cytochrome b sequences
1998
Sequence data derived from a 306 bp fragment of mitochondrial cytochrome b and molecular variance estimates were used to investigate the genetic population structure of the endangered and endemic lizard Podarcis atrata of the Columbretes archipelago (Mediterranean, Spain). Our results show a very high and significant among-population genetic differentiation. FST values and phylogenetic analyses confirm the evolutionary distinctiveness of P. atrata populations, suggesting that the populations of these islands deserve special protection measures. The populations of the two islands Columbrete Grande and Mancolibre are less differentiated than those of Foradada and Lobo, and seem to have retain…
Fighting carbon loss of degraded peatlands by jump-starting ecosystem functioning with ecological restoration
2015
Degradation of ecosystems is a great concern on the maintenance of biodiversity and ecosystem services. Ecological restoration fights degradation aiming at the recovery of ecosystem functions such as carbon (C) sequestration and ecosystem structures like plant communities responsible for the C sequestration function. We selected 38 pristine, drained and restored boreal peatland sites in Finland and asked i) what is the long-term effect of drainage on the peatland surface layer C storage, ii) can restoration recover ecosystem functioning (surface layer growth) and structure (plant community composition) and iii) is the recovery of the original structure needed for the recovery of ecosystem f…
Forest management is associated with physiological stress in an old–growth forest passerine
2003
We investigated how physiological stress in an area-sensitive old-growth forest passerine, the Eurasian treecreeper (Certhia familiaris), is associated with forest fragmentation and forest structure. We found evidence that the concentrations of plasma corticosterone in chicks were higher under poor food supply in dense, young forests than in sparse, old forests. In addition, nestlings in large forest patches had lower corticosterone levels and a better body condition than in small forest patches. In general, corticosterone levels were negatively related to body condition and survival. We also found a decrease in corticosterone levels within the breeding season, which may have been a result …
Current anthropogenic pressures on agro-ecological protected coastal wetlands
2015
Coastal wetlands are areas that suffer from great pressure. Much of it is due to the rapid development of the surrounding artificial landscapes, where socio-economic factors lead to alterations in the nearby environment, affecting the quality of natural and agricultural systems. This work analyses interconnections among landscapes under the hypothesis that urban-artificial impacts could be detected on soils and waters of an agro-ecological protected area, L'Albufera de Valencia Natural Park, located in the vicinity of the City of Valencia, Spain. The methodological framework developed addresses two types of anthropogenic pressure: (1) direct, due to artificialisation of soil covers that cau…
Buffer strips can pre-empt extinction debt in boreal streamside habitats
2013
Background Conservation of biological diversity and economical utilization of natural resources form an almost inevitable confrontation between the two. In practice, however, a balance between the two ought to be found, and in managed boreal forests, preservation of woodland key habitats is increasingly used strategy to safeguard biological diversity. According to the Finnish Forests Act, certain Forest Act habitat (FAH) types must be safeguarded, provided they are clearly distinguishable from their surroundings. Furthermore, once the habitat has been identified as a FAH, its special characteristics must not be altered. Both of these aspects contain ambiguities that potentially undermine th…
Ecological and agronomic importance of the plant genus Lotus. Its application in grassland sustainability and the amelioration of constrained and con…
2010
The genus Lotus comprises around 100 annual and perennial species with worldwide distribution. The relevance of Lotus japonicus as a model plant has been recently demonstrated in numerous studies. In addition, some of the Lotus species show a great potential for adaptation to a number of abiotic stresses. Therefore, they are relevant components of grassland ecosystems in environmentally constrained areas of several South American countries and Australia, where they are used for livestock production. Also, the fact that the roots of these species form rhizobial and mycorrhizal associations makes the annual L. japonicus a suitable model plant for legumes, particularly in studies directed to r…