1,796 research outputs found
Patrones de distribución de los Carabidae ibéricos (Insecta, Coleoptera)
We have categorised the 1336 species and subspecies of the Iberian Peninsula according to the chorotype classification proposed by Vigna Taglianti et al. (1992), modified by the addition of new chorotypes. The Iberian Peninsula is noticeable among the different European and Circum-Mediterranean regions by the high proportion of endemic taxa (43.1%). The old age and stability of the northern half, the extreme position of the Peninsula within the Eurasiatic continent, alpine tectonics and abundance of caves are among the factors that have probably contributed to the origin of a distinctive fauna. Taxa with a large distribution pattern are predominant at a regional scale; the proportion of endemic taxa increases to the North and in mountain regions; Mediterranean elements are more frequent in the South whereas European elements increase in the northern half. Adaptation to a Mediterranean climatic regime and dispersal are two of the factors causing these patterns. The Peninsula is poor in Afrotropical elements, probably because of the strong isolation derived from the Sahara Desert. The Balearic Islands have high proportions of widely distributed and Mediterranean taxa, what suggests a main role of dispersal in the colonisation of the archipelago. The proportion of endemic taxa in Mallorca (7.8%) is intermediate between that of Sardinia and Sicily; in spite of a relatively long isolation, the Balearic Islands are small in size and moderately rich in caves, what explains that most endemic taxa are found in the lowlands.Se han categorizado las 1336 especies y subespecies de la fauna ibérica de Carabidae, usando los corotipos propuestos por Vigna Taglianti et al. (1992), los cuales se han completado con algunos otros adicionales. La Península Ibérica destaca entre las diversas regiones europeas y circunmediterráneas por la elevada proporción de elementos endémicos (43,1%). La antigüedad y estabilidad de la mitad norte peninsular, el aislamiento de la región, los plegamientos alpinos y la abundancia de cuevas, son factores que probablemente han contribuido a su singularidad faunística. Los elementos de amplia distribución predominan a la escala regional; las proporciones de endemismos son mayores hacia el Norte y en las zonas de montaña; la de los elementos mediterráneos se incrementa hacia el Sur, al contrario de lo que ocurre con los elementos europeos. La adaptación al régimen climático mediterráneo y la dispersión son dos de los factores que probablemente causan estos patrones. La Península es pobre en elementos afrotropicales, posiblemente debido al aislamiento causado por la barrera natural del Sahara. Las Islas Baleares tienen altas proporciones de elementos de amplia distribución y mediterráneos, lo que sugiere el papel relevante de la dispersión en la colonización de las islas. La proporción de endemismos de Mallorca (7,8%) es intermedia entre la de Cerdeña y Sicilia; a pesar de su aislamiento las Baleares son de tamaño pequeño y tienen un abundancia moderada de medios favorables para la especiación, como ocurre con las cuevas, lo que explica que la mayoría de los endemismos se encuentren en zonas abiertas de baja altitud
Handwritten word-image retrieval with synthesized typed queries
We propose a new method for handwritten word-spotting which does not require prior training or gathering examples for querying. More precisely, a model is trained “on the fly ” with images rendered from the searched words in one or multiple computer fonts. To reduce the mismatch between the typed-text prototypes and the candidate handwritten images, we make use of: (i) local gradient histogram (LGH) features, which were shown to model word shapes robustly, and (ii) semi-continuous hidden Markov models (SC-HMM), in which the typed-text models are constrained to a “vocabulary ” of handwritten shapes, thus learning a link between both types of data. Experiments show that the proposed method is effective in retrieving handwritten words, and the comparison to alternative methods reveals that the contribution of both the LGH features and the SC-HMM is crucial. To the best of the authors ’ knowledge, this is the first work to address this issue in a non-trivial manner
VIE Project: Cultural values and socioeconomic factors as determinants of entrepreneurial intentions
This paper describes a research project currently being developed by the authors. It aims to analyse the role played by psychosocial, cultural and socioeconomic factors in shaping the entrepreneurial intention. Survey methods will be used on a population of potential entrepreneurs (having not yet performed actual entrepreneurial behaviours). In this sense, undergraduate students and individuals contacting business support centres will be considered as part of the sample. We expect to get a clearer understanding of the psychosocial elements, socioeconomic factors and cultural values affecting the venture-creation decision. The results would be important to policy makers (showing them what to encourage), to practitioners (what to do better), and to researchers (what to clarify)
Dynamic Kinetic Resolution of Hetero biaryl Ketones by Zinc- Catalyzed Asymmetr ic Hydrosil ylation
Adiastereo-
and
highly
enantioselective
dynamic
kinetic
resolution
(DKR)
of configurationally
labile
hetero-
biaryl
ketones
is described.
The
DKR
proceeds
by zinc-
catalyze
dhydrosilylation
of the carbonyl
group
,thus leading
to
secondary
alcohols
bearing
axial
and
central
chirality
.The
strategy
relies
on the labilization
of the stereogenic
axis
that
takes
place
thanks
to aLewis
acid–base
interaction
between
anitrogen
atom
in the heterocycle
and
the ketone
carbonyl
group
.The synthetic
utility
of the methodology
is demonstrated
through
stereospecific
transformations
into either
N,N-ligands
or appealing
axially
chiral,
bifunctional
thiourea
organocata-
lysts.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P, CTQ2016-76908-C2-2-P, contract RYC-2013-12585)European FEDER FundsJunta de Andalucía (Grant 2012/FQM 10787)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement n 8 8 291780
Google es noticia. Transformación de los marcos informativos sobre Google en la prensa española
Fundada en 1998, en menos de veinte años, Google se ha convertido en una de las mayores multinacionales del mundo. Esta investigación estudia las informaciones periodísticas sobre Google, desde la perspectiva de la teoría del encuadre (framing). La pregunta propuesta es: ¿Ha cambiado la imagen que la prensa española proyecta sobre Google desde los inicios de la compañía a los últimos años? Para responder, se ha hecho un análisis de contenido de todos los textos periodísticos sobre Google publicados en 2004 y 2014 por “El País”, “El Mundo”, “ABC” y “La Vanguardia”. Mediante un protocolo de análisis, se han detectado los marcos informativos –news frames– presentes en cada texto periodístico. Los resultados de la investigación ponen de manifiesto que se ha producido una transformación de los marcos informativos sobre Google: de ser mayoritariamente positivos para la compañía estadounidense, a ser negativos. También se ha detectado que, en 2004, las informaciones sobre la empresa ponían el foco en cuestiones de tipo económico; mientras que, en 2014, los periódicos analizados prefirieron atribuir a Google la responsabilidad de una serie de problemas. El texto concluye que Google ya no es enmarcada por los principales diarios sólo como una empresa tecnológica que logra excelentes resultados económicos, sino como una compañía cuyas actividades afectan –con frecuencia, negativamente– a determinadas personas, grupos humanos y a otras compañías
Homage from Revista do Instituto de Medicina Tropical de São Paulo in Memory of Dr. Enrique Tejera (1889-1980)
Rhodium and Iridium complexes with a new scorpionate phosphane ligand
A straightforward synthesis of a new hybrid scorpionate ligand [(allyl)2B(CH2PPh2)(Pz)]− ([A2BPN]−) is reported. Coordination to rhodium resulted in square-planar complexes [Rh(κ2-A2BPN)(L)(L′)] [L = L′ = 1/2cod (1,5-cyclooctadiene), CNtBu, CO (6); L = CO, L′ = NH3, pyridine, PPh3, PMe3] for which spectroscopic data and the molecular structure of [Rh(κ2-A2BPN)(CO)PPh3] (11) indicate the ligand to be κN,κP-bound to rhodium with two dangling free allyl groups. Studies in solution point out that the six-membered Rh–N–N–B–C–P metallacycle undergoes a fast inversion in all of them. The bis(carbonyl) complex 6 easily loses a CO group to give [{Rh(A2BPN)(CO)}2], a dinuclear compound in which two mononuclear subunits are brought together by two bridging allyl groups. Coordination to iridium is dominated by a tripodal κN,κP,η2-C═C binding mode in the TBPY-5 complexes [Ir(κ3-A2BPN)(L)(L′)] [L = L′ = 1/2cod (3), CNtBu (5), CO (7); L = CO, L′ = PPh3 (13), PMe3 (14), H2C═CH2, (17), MeO2CC≡CCO2Me (dmad, 18)], as confirmed by the single-crystal structure determination of complexes 3 and 18. A fast exchange between the two allyl arms is observed for complexes having L = L′ (3, 5, and 7), while those having CO and L ligands (14, 17, and 18) were found to be nonfluxional species. An exception is complex 13, which establishes an equilibrium with the SP-4 configuration. Protonation reactions on complexes 13 and 14 with HCl yielded the hydride complex [Ir(κ2-A2BPN)(CO)(Cl)(H)PPh3] (15) and the C-alkyl compound [Ir{κ3-(allyl)B(CH2CHCH3)(CH2PPh2)(Pz)}(Cl)(CO)PMe3] (16), respectively. The bis(isocyanide) complex 5 reacts with dmad to form [Ir(κ2-A2BPN)(CNtBu)2(dmad)]. On the whole, the electronic density provided to the metal by the [A2BPN]− ligand is very sensitive to the coordination mode. The basicity of the new ligand is similar to that of the TpMe2 ligand in the κN,κP mode but comparable to Tp if coordinated in the κN,κP,η2-C═C mode.This research was supported by the MICINN/FEDER (Project CTQ2011-22516, Spain), Gobierno de Aragón (GA)/FSE (E70), and GA-La Caixa (Grant 2012/GA LC 057). A.L.S. thanks MICINN/FEDER for a fellowship.Peer Reviewe
Linear Strain Tensors on Hyperbolic Surfaces and Asymptotic Theories for Thin Shells
We perform a detailed analysis of the solvability of linear strain equations
on hyperbolic surfaces. We prove that if the surface is a smooth
noncharacteristic region, any first order infinitesimal isometry can be matched
to an infinitesimal isometry of an arbitrarily high order. The implications of
this result for the elasticity of thin hyperbolic shells are discussed
Ranking the Azorean Natural Forest Reserves for conservation using their endemic arthropods
Copyright © 2000 Kluwer Academic Publishers.Endemic arthropods were used to evaluate the conservation value of the 16 Natural Forest Reserves (NFRs) of the Azores (Macaronesia). For each of the 280 known Azorean endemic species of arthropods, a rarity index was calculated, using distribution and abundance data obtained from the literature. In addition, several scoring indices were used to rank the 16 NFRs. Frequency distributions of the rarity index indicated that there was a tendency for a greater proportion of the commonest species being represented in the NFRs in contrast with a lower representation of the rarest species. About 60% of the endemic arthropod species that were recorded from the NFRs are single NFR endemics , that is, are known from only one of the 16 NFRs. Species richness was considered to be a very good surrogate measure of the conservation value of the 16 NFRs under study. The fact that the six highest ranked NFRs (using a composite multi-criteria index) are located in different islands has some important conservation management implications; to preserve a large proportion of the Azorean arthropod biodiversity there is a need to protect sites in all islands. If the five highest ranked NFRs are correctly managed in terms of conservation, then at least 80% of the endemic arthropods known from the NFRs could be protected. Most of the tested taxa (Acari-Oribatei; Lepidoptera; Diptera; Coleoptera) are good surrogates of the overall total set of species present in the 16 NFRs when using a species richness index
Efficiency of university education: A partial frontier analysis
This article investigates the efficiency of the university education using two linked databases (Saber Pro and Saber 11) from the Colombian Institute for Evaluation of Education (ICFES) corresponding to 2014. We use a non-parametric frontier approach that combines the "order m" technique with the concept of a meta-frontier to disaggregate students' total efficiency in generic skills in quantitative reasoning, critical reading, and written communication, into the parts attributable to the students themselves and the university. The analysis is performed by academic programme and by education sector (public vs. private). Results indicate that most of the inefficiency of students in the assessment of generic skills in higher education is attributable to the students themselves and a significant number of students could improve their performance in the assessment in each of the academic programmes if they performed as efficiently as those located on the frontier. Furthermore, the inefficiency share of students varies between academic programmes and university sectors, with students in the private sector more inefficient than those in the public sector in some and less inefficient in others. This research constitutes the first application of the technique of "order m" with the approach of the meta-frontier for the analysis of educational efficiency using data at the student and university levels
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