233 research outputs found
Caracoles terrestres (Gastropoda, Stylommatophora) del Parque Natural de la Muntanya de Montserrat (Barcelona, NE penĂnsula IbĂ©rica)
Es dĂłna a conèixer l’inventari actualitzat dels cargols terrestres del Parc Natural de Montserrat, amb 73 tĂ xons. Per complir aquest objectiu ha calgut fer una revisiĂł bibliogrĂ fica de mĂ©s de 130 publicacions. Alhora, s’ha dut a terme, de forma planificada, un treball de camp en diverses localitats del massĂs amb representaciĂł dels diferents hĂ bitats, amb l’objectiu de descriure de forma preliminar les comunitats de cargols terrestres de l’à mbit d’estudi. S’han estudiat un total de 342 lots d’espècies i com a resultat se n’han identificat 50. Els cargols terrestres mĂ©s ben representats han resultat ser Pomatias elegans, Helicigona lapicida, Pseudotachea splendida, Abida polyodon i Otala punctata. Entre les espècies catalogades destaquen, pel fet de ser endemismes d’aquesta part de la Serralada Prelitoral Catalana, Abida secale bofilli, Montserratina bofilliana i Xerocrassa montserratensis. Amb els resultats del treball de camp s’amplia el catĂ leg faunĂstic del Parc Natural de Montserrat. Hygromia cinctella, Microxeromagna lowei, Paralaoma servilis i Punctum pygmaeum sĂłn noves cites a la zona. Finalment, es proposen algunes lĂnies de recerca i de conservaciĂł sobre l’endemisme Xerocrassa montserratensis, emparat pel Decret 328/1992 d’aprovaciĂł del Pla d’espais d’interès natural (PEIN).The inventory of 73 land snails in the Natural Park of Montserrat was updated following the review of 130 publications. Planned field study was also conducted in areas of different habitats on the Montserrat mountain to provide a preliminary description of the communities of land snails in the study area. A total of 342 samples of land snails were studied and 50 species were identified. The most frequent were Pomatias elegans, Helicigona lapicida, Pseudotachea splendida, Abida polyodon and Otala punctata. In this region of the prelittoral Catalan mountain range, the level of endemism was high for Abida secale bofilli, Montserratina bofilliana and Xerocrassa montserratensis. The results of the field work extend the faunistic catalogue of the Natural Park of Montserrat to include references to Hygromia cinctella, Microxeromagna lowei, Paralaoma servilis and Punctum pygmaeum in the area. Finally, investigation and conservation programmes are suggested for the endemic species Xerocrassa montserratensis, protected by the Plan for Areas of Natural Interest (PEIN) approved by Decree 328/1992.Se da a conocer el inventario actualizado de los caracoles terrestres del Parque Natural de Montserrat, con 73 taxones. Para cumplir este objetivo ha sido necesario efectuar una revisiĂłn bibliográfica de más de 130 publicaciones. A la vez, se ha llevado a cabo, de modo planificado, un trabajo de campo en diferentes localidades del macizo con representaciĂłn de los diferentes hábitats, con el objetivo de describir de modo preliminar las comunidades de caracoles terrestres del ámbito de estudio. Se han estudiado un total de 342 lotes de especies y como resultado se han identificado 50 especies. Los caracoles terrestres mejor representados han resultado ser Pomatias elegans, Helicigona lapicida, Pseudotachea splendida, Abida polyodon y Otala punctata. De las especies catalogadas destacan por ser endemismos de esta parte de la Cordillera Prelitoral Catalana Abida secale bofilli, Montserratina bofilliana y Xerocrassa montserratensis. Con los resultados del trabajo de campo se amplĂa el catálogo faunĂstico del Parque Natural de Montserrat, siendo Hygromia cinctella, Microxeromagna lowei, Paralaoma servilis y Punctum pygmaeum nuevas citas en la zona. Finalmente, se proponen algunas lĂneas de investigaciĂłn y de conservaciĂłn sobre el endemismo Xerocrassa montserratensis, amparado por el Decreto 328/1992 de aprobaciĂłn del Plan de Espacios de InterĂ©s Natural (PEIN)
Inventari faunĂstic dels mol·luscs continentals de la serra de Collserola (Barcelona, NE de la penĂnsula ibèrica): resultat d'una revisiĂł bibliogrĂ fica
Mitjançant una revisiĂł bibliogrĂ fica de publicacions editades des de 1868 fins a 2004, s'ha elaborat un inventari preliminar de la fauna malacològica de la serra de Collserola, amb 99 espècies. L'Ă rea geogrĂ fica estuÂdiada Ă©s un dels espais naturals ibèrics amb mĂ©s referències bibliogrĂ fiques de mol·luscs terrestres i d'aigua dolça. Tanmateix, resten per resoldre moltes llacunes sobre alguns dels tĂ xons. En concret, manquen localitzacions recents de diverses espècies per verificar que actualment sĂłn presents dins l'Ă mbit del parc de Collserola. Entre les espècies catalogades destaquen alguns elements endèmics de gran interès com Xerocrassa betulonensis (Bofill, 1879), Zonitoides jaccetanicus (Bourguignat, 1870) i Montserratina martorelli (Bourguignat, 1870). Els resultats de la revisiĂł bibliogrĂ fica posen de manifest la gran contribuciĂł de la malacofauna a la biodiversitat de la serra de Collserola i alhora poden constituir una eina molt Ăştil per gestionarÂżla.
Paraules clau: Inventari, Mol·luscos continentals, Gastròpodes, Bivalves, Biodiversitat, Parc de Collserola, Barcelona.Following the bibliographic review of articles published between 1868 and 2004 a preliminary inventary of 99 species of the malacologic fauna on the Collserola mountains was compiled. The geographic area studied is one of the natural Iberian spaces with the most bibliographic references for land and fresh water molluscs. However, much remains to be resolved concerning some of the taxa. In particular, recent locations of several species have to be verified in the Collserola Park. These include several catalogued species of great interest, such as Xerocrassa betulonensis (Bofill, 1879), Zonitoides jaccetanicus (Bourguignat, 1870) and Montserratina martorelli (Bourguignat, 1870). This bibliographic review shows the significant contribution of the malacofauna to the biodiversity of the Collserola mountains and also demonstrates its value as a useful tool for their management.
Key words: Inventary, Continental mollluscs, Gasteropodes, Bivalves, Biodiversity, Collserola Park, Barcelona.Mitjançant una revisiĂł bibliogrĂ fica de publicacions editades des de 1868 fins a 2004, s'ha elaborat un inventari preliminar de la fauna malacològica de la serra de Collserola, amb 99 espècies. L'Ă rea geogrĂ fica estuÂdiada Ă©s un dels espais naturals ibèrics amb mĂ©s referències bibliogrĂ fiques de mol·luscs terrestres i d'aigua dolça. Tanmateix, resten per resoldre moltes llacunes sobre alguns dels tĂ xons. En concret, manquen localitzacions recents de diverses espècies per verificar que actualment sĂłn presents dins l'Ă mbit del parc de Collserola. Entre les espècies catalogades destaquen alguns elements endèmics de gran interès com Xerocrassa betulonensis (Bofill, 1879), Zonitoides jaccetanicus (Bourguignat, 1870) i Montserratina martorelli (Bourguignat, 1870). Els resultats de la revisiĂł bibliogrĂ fica posen de manifest la gran contribuciĂł de la malacofauna a la biodiversitat de la serra de Collserola i alhora poden constituir una eina molt Ăştil per gestionarÂżla.
Paraules clau: Inventari, Mol·luscos continentals, Gastròpodes, Bivalves, Biodiversitat, Parc de Collserola, Barcelona
Moluscos terrestres y de agua dulce de la sierra de Collserola (Barcelona, NE penĂnsula IbĂ©rica)
A malacological survey was made taking into account all the 91 1x1 km UTM grid squares that cover the area of the Collserola mountains, Barcelona (north-eastern Iberian peninsula). From 108 sampled localities, 1,261 records of molluscs were obtained. A total of 73 species were identified: seven freshwater species, 11 slugs, and 55 land molluscs. The first discussions on the results and a draft of the initial conclusions are shown. Information on dominant gastropod habitat preference in the ecosystems of Collserola is also provided.Se ha efectuado un muestreo de la fauna de moluscos de 108 localidades, distribuidas entre las 91 cuadrĂculas 1x1 km UTM que cubren la totalidad del Parque de Collserola, Barcelona (noreste de la penĂnsula IbĂ©rica). Se han estudiado 1.261 muestras de las que se deduce la presencia de 73 taxones, 7 correspondientes a moluscos de agua dulce, 11 a babosas y 55 a caracoles terrestres. Se presenta la primera valoraciĂłn de los resultados de la investigaciĂłn de campo realizada y se dan a conocer las primeras conclusiones. Asimismo, se aporta informaciĂłn sobre las preferencias de hábitat de las especies de moluscos gasterĂłpodos dominantes en los ecosistemas de la sierra de Collserola
Fauna malacológica de Les Planes de Son y La Mata de València (Alt Àneu, Pallars Sobirà , Pirineo Catalán): revisión biliográfica y nuevos datos
La revisiĂł de citacions bibliogrĂ fiques situades a les Planes de Son i la Mata de València (municipi d’Alt Ă€neu, Pallars SobirĂ ) ha permès identificar 33 espècies de mol·luscs (set de les quals corresponents a llimacs) presents històricament en la zona. Una campanya de camp portada a terme recentment (2006–2007) ha detectat 50 espècies de mol·luscs no-llimacs, dues de les quals representades amb dues subespècies cadascuna. Es proporcionen les dades detallades dels dos inventaris faunĂstics.
Paraules clau: Pirineus, Fauna, Mollusca.The survey of bibliograpic information on the presence of molluscs at the Planes de Son and Mata de València (municipality of Alt Àneu, county of Pallars Sobirà , Catalan Pyrenees) has accounted for a list of 33 species of molluscs (seven of them are slugs) inhabiting historically this area. A current field survey (2006-2007) has detected 50 species of molluscs not slugs, two of these species are splitted in two subspecies. Detailed data from both faunistic inventories are provided.
Key words: Pyrenees, Fauna, Mollusca.La revisiĂłn de las citas bibliográficas situadas en Les Planes de Son y La Mata de València (municipio de Alt Ă€neu, comarca del Pallars SobirĂ , Pirineo Catalán) ha permitido identificar 33 especies de moluscos (siete de ellas correspondientes a babosas) presentes histĂłricamente en la zona. Una reciente campaña de campo (2006-2007) ha detectado 50 especies de moluscos no babosas, dos de ellas representadas con dos subespecies cada una. Se proporcionan los datos detallados de los dos inventarios faunĂsticos.
Palabras clave: Pirineo, Fauna, Mollusca
Influencia de la altitud en la riqueza de especies de moluscos: variaciones en el valle de AlinyĂ , Alt Urgell, Lleida
The species richness of land molluscs is negatively correlated with altitude, while the altitudinal range of the species inhabiting at higher elevations is greater than in low levels. At the low scale of this study factors other than elevation may account better for the species richness.La riqueza de especies de moluscos terrestres está negativamente correlacionada con la altitud, mientras que el rango altitudinal de las especies lo está positivamente. En estudios locales como éste la altitud no explica suficientemente la distribución de la riqueza de especies
Cosmological horizons and reconstruction of quantum field theories
As a starting point, we state some relevant geometrical properties enjoyed by
the cosmological horizon of a certain class of Friedmann-Robertson-Walker
backgrounds. Those properties are generalised to a larger class of expanding
spacetimes admitting a geodesically complete cosmological horizon \scrim
common to all co-moving observers. This structure is later exploited in order
to recast, in a cosmological background, some recent results for a linear
scalar quantum field theory in spacetimes asymptotically flat at null infinity.
Under suitable hypotheses on , encompassing both the cosmological de Sitter
background and a large class of other FRW spacetimes, the algebra of
observables for a Klein-Gordon field is mapped into a subalgebra of the algebra
of observables \cW(\scrim) constructed on the cosmological horizon. There is
exactly one pure quasifree state on \cW(\scrim) which fulfils a
suitable energy-positivity condition with respect to a generator related with
the cosmological time displacements. Furthermore induces a preferred
physically meaningful quantum state for the quantum theory in the
bulk. If admits a timelike Killing generator preserving \scrim, then the
associated self-adjoint generator in the GNS representation of has
positive spectrum (i.e. energy). Moreover turns out to be invariant
under every symmetry of the bulk metric which preserves the cosmological
horizon. In the case of an expanding de Sitter spacetime, coincides
with the Euclidean (Bunch-Davies) vacuum state, hence being Hadamard in this
case. Remarks on the validity of the Hadamard property for in more
general spacetimes are presented.Comment: 32 pages, 1 figure, to appear on Comm. Math. Phys., dedicated to
Professor Klaus Fredenhagen on the occasion of his 60th birthda
Wedge Local Deformations of Charged Fields leading to Anyonic Commutation Relations
The method of deforming free fields by using multiplication operators on Fock
space, introduced by G. Lechner in [11], is generalized to a charged free field
on two- and three-dimensional Minkowski space. In this case the deformation
function can be chosen in such a way that the deformed fields satisfy
generalized commutation relations, i.e. they behave like Anyons instead of
Bosons. The fields are "polarization free" in the sense that they create only
one-particle states from the vacuum and they are localized in wedges (or "paths
of wedges"), which makes it possible to circumvent a No-Go theorem by J. Mund
[12], stating that there are no free Anyons localized in spacelike cones. The
two-particle scattering matrix, however, can be defined and is different from
unity
Conformally invariant wave-equations and massless fields in de Sitter spacetime
Conformally invariant wave equations in de Sitter space, for scalar and
vector fields, are introduced in the present paper. Solutions of their wave
equations and the related two-point functions, in the ambient space notation,
have been calculated. The ``Hilbert'' space structure and the field operator,
in terms of coordinate independent de Sitter plane waves, have been defined.
The construction of the paper is based on the analyticity in the complexified
pseudo-Riemanian manifold, presented first by Bros et al.. Minkowskian limits
of these functions are analyzed. The relation between the ambient space
notation and the intrinsic coordinates is then studied in the final stage.Comment: 21 pages, LaTeX, some details adde
Propagation of Magnetic Avalanches in Mn12Ac at High Field Sweep Rates
Time-resolved measurements of the magnetization reversal in single crystals of Mn 12 Ac in pulsed magnetic fields, at magnetic field sweep rates from 1.5     kT / s up to 7     kT / s , suggest a new process that cannot be scaled onto a deflagrationlike propagation driven by heat diffusion. The sweep rate dependence of the propagation velocity, increasing from a few 100     m / s up to the speed of sound in Mn 12 Ac , indicates the existence of two new regimes at the highest sweep rates, with a transition around 4     kT / s that can be understood as a magnetic deflagration-to-detonation transition
On low energy quantum gravity induced effects on the propagation of light
Present models describing the interaction of quantum Maxwell and
gravitational fields predict a breakdown of Lorentz invariance and a non
standard dispersion relation in the semiclassical approximation. Comparison
with observational data however, does not support their predictions. In this
work we introduce a different set of ab initio assumptions in the canonical
approach, namely that the homogeneous Maxwell equations are valid in the
semiclassical approximation, and find that the resulting field equations are
Lorentz invariant in the semiclassical limit. We also include a
phenomenological analysis of possible effects on the propagation of light, and
their dependence on energy, in a cosmological context.Comment: 12 page
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