Search results for "Category"
showing 10 items of 4660 documents
Deteriorating Weather Conditions Predict the use of Suboptimal Stopover Sites by Aquatic WarblersAcrocephalus paludicola
2011
Abstract. The Aquatic Warbler Acrocephalus paludicola is a globally threatened songbird and its decline is related to habitat loss. Accordingly, most studies dealing with the stopover ecology of this species have been chiefly focused on the habitat use and the availability of suitable habitats along its route of migration. In contrast, much less attention has been paid to other environmental causes potentially explaining the use of stopover sites. Our aim here was to investigate whether the Aquatic Warbler at an apparently suboptimal stopover site with small area of suitable habitats stops over only during adverse weather conditions. We used data obtained at a suboptimal (Jaizubia marshland…
Aerosol properties of the Eyjafjallajökull ash derived from sun photometer and satellite observations over the Iberian Peninsula
2012
The Eyjafjallajökull ash that crossed over Spain and Portugal on 6e12 May 2010 has been monitored by a set of operational sun photometer sites within AERONET-RIMA and satellite sensors. The sun photometer observations (aerosol optical depth, coarse mode concentrations) and ash products from IASI and SEVIRI satellite sensors, together with FLEXPART simulations of particle transport, allow identifying the volcanic aerosols. The aerosol columnar properties derived from inversions were investigated, indicating specific properties, especially regarding the absorption. The single scattering albedo was high (0.95 at 440 nm) and nearly wavelength independent, although with slight decrease with wave…
Alternative Stories of Agricultural Origins: The Neolithic Spread in the Iberian Peninsula
2017
The spread of agriculture from the Near East to Europe has long been a subject of intense archaeological study and debate in light of the social and economic changes that occurred and were set in motion as a result of this transition. Despite the attention paid to this important process, a consensus is far from being reached. Perhaps for these reasons, new methods and theoretical approaches have often been applied to the questions surrounding the spread of agriculture first. Recently, computational modeling has emerged as a promising technique for the study of the origins of agriculture. Our approach employs an agent-based computational model of agricultural spread for the Iberian Peninsula…
Genetic and environmental contribution to postural balance of older women in single and dual task situations
2005
Abstract The purpose of the present study was to examine the effect of a second task on postural balance and to determine the role of genetic influences on postural balance when dual tasking among 206 monozygotic and 227 dizygotic female twins, aged 63–76 years. Balance was measured as medio-lateral and antero-posterior velocity of the centre of pressure (COP) (mm/s) and velocity moment (mm2/s) while standing on a force platform. Doing an arithmetic task increased movement of the COP while the hand motor task had no effect on movement of the COP. The genetic contribution to balance in the single task situation was minor (14%, 95% confidence interval, CI: 11–35%) whereas in the dual task sit…
Short-term effects of different tillage in a sustainable farming system on nematode community structure
2000
This study investigated the effects of different tillage practices on the nematode community structure. The different tillage systems were: untilled control, conventional deep plough, two-layer plough and cultivator. Sampling was carried out in a field experiment at Worrstadt-Rommersheim (Rhineland-Palatinate, Germany) in order to study the effects of these tillage systems in a sustainable farming system. Soil samples were taken every 3 months from June 1994 to March 1995 and divided into two depths of 0–10 and 10–20 cm in order to study the vertical distribution of nematode density and community structure. Nematode density was significantly reduced after the first tillage. The second tilla…
The future of temporary wetlands in drylands under global change
2021
The Andalusian International University held a workshop entitled Temporary wetlands’ future in drylands under the projected global change scenario in March 2020 in Baeza, Spain, with 26 participants from 10 countries. The workshop objectives were to promote international cooperation and scientific exchange on the conservation and protection of temporary wetlands. The participants highlighted the extreme conditions that temporary and permanent wetlands, ponds, and shallow lakes are currently facing and predicted a dismal future for these systems due to climate change. To foster a holistic view of these ecosystems, the workshop included wetland watersheds. It was concluded that the main threa…
Medio físico y características constructivas de galerías drenantes de aguas subálveas en ambientes semiáridos del sudeste español y Túnez
2021
Draining galleries are water collection systems that occurs frequently in various geomorphic contexts of semi-arid environments. In this article, we study those that take advantage of subalveal waters by means of different construction techniques, mainly 'cimbras' and 'cimbra-zanjas'. A comparison has been made between the Tunisian galleries and those of the Spanish SE that have these two characteristics: the exploitation of subsubalveal waters and surface detritic aquifers, and rainfall characteristics of semi-arid climates, specifically annual total rainfall between 300 and 400 mm. The work analyzes the environmental contexts of the selected galleries, especially geology, geomorphology, r…
On monadic quantale algebras: basic properties and representation theorems
2010
Motivated by the concept of quantifier (in the sense of P. Halmos) on different algebraic structures (Boolean algebras, Heyting algebras, MV-algebras, orthomodular lattices, bounded distributive lattices) and the resulting notion of monadic algebra, the paper introduces the concept of a monadic quantale algebra, considers its properties and provides several representation theorems for the new structures.
On a paper of Beltrán and Shao about coprime action
2020
Abstract Assume that A and G are finite groups of coprime orders such that A acts on G via automorphisms. Let p be a prime. The following coprime action version of a well-known theorem of Ito about the structure of a minimal non-p-nilpotent groups is proved: if every maximal A-invariant subgroup of G is p-nilpotent, then G is p-soluble. If, moreover, G is not p-nilpotent, then G must be soluble. Some earlier results about coprime action are consequences of this theorem.
Rank two aCM bundles on the del Pezzo fourfold of degree 6 and its general hyperplane section
2018
International audience; In the present paper we completely classify locally free sheaves of rank 2 with vanishing intermediate cohomology modules on the image of the Segre embedding $\mathbb{P}^2$ x $\mathbb{P}^2 \subseteq \mathbb{P}^8$ and its general hyperplane sections.Such a classification extends similar already known results regarding del Pezzo varieties with Picard numbers 1 and 3 and dimension at least 3.