Top dimensional group of the basic intersection cohomology for singular riemannian foliations

It is known that, for a regular riemannian foliation on a compact manifold, the properties of its basic cohomology (non-vanishing of the top-dimensional group and Poincar\'e Duality) and the tautness of the foliation are closely related. If we consider singular riemannian foliations, there is little or no relation between these properties. We present an example of a singular isometric flow for which the top dimensional basic cohomology group is non-trivial, but its basic cohomology does not satisfy the Poincar\'e Duality property. We recover this property in the basic intersection cohomology. It is not by chance that the top dimensional basic intersection cohomology groups of the example are isomorphic to either 0 or $\mathbb{R}$. We prove in this Note that this holds for any singular riemannian foliation of a compact connected manifold. As a Corollary, we get that the tautness of the regular stratum of the singular riemannian foliation can be detected by the basic intersection cohomology.Comment: 11 pages. Accepted for publication in the Bulletin of the Polish Academy of Science

Espacios visibles. Espacios invisibles. Mujer y memoria en la Salamanca del siglo XVI (selección documental). [Reseña]

Reseña de: Gloria García González - Mª Luz de Prado Herrera (coords.), Espacios visibles. Espacios invisibles. Mujer y memoria en la Salamanca del siglo XVI (selección documental), prólogo de Adriana Valerio, Universidad Pontificia de Salamanca, Salamanca 2006

Germination differences between seeds from apical and basal fruits of "Camelina microcarpa" Andrz. ex DC. produced in two different climates

En el presente trabajo se han estudiado las diferencias de germinación entre semillas de una población de “Camelina microcarpa” Andrz. ex DC. producidas en los frutos apicales y basales de las mismas infrutescencias, y producidas en dos condiciones climáticas diferentes (Lleida y Minnesota). Las semillas apicales germinaron más y antes que las basales, principalmente cuando fueron producidas en Lleida, mientras que estas diferencias se difuminaron en las semillas procedentes de Minnesota; estas últimas semillas también germinaron en mayor medida que las de Lleida. A pesar de las diferencias, los ritmos de germinación fueron similares en casi todos los casos. Los resultados ponen de manifiesto la importancia del lugar de producción de las semillas de cara a su posible comercialización como cultivo oleaginoso.Germination characteristics of seeds collected from apical and basal fruits of the infrutescences, and produced in two different climatic conditions (Lleida and Minnesota) were studied. Apical seeds germinated more and earlier than basal seeds, mainly when they were produced in Lleida, while these differences blur between seeds produced in Minnesota, which germinated in a greater amount than those of Lleida. Despite these differences, germination rates were similar in all cases. The results show the importance of the seed production site if these species was considered as a potential commercial oilseed crop

Dielectric control of spin in semiconductor spherical quantum dots

The ground state electronic configuration of semiconductor spherical quantum dots populated with different numbers of excess electrons, for different radii and dielectric constants of the embedding medium is calculated and the corresponding phase diagram drawn. To this end, an extension of the spin density functional theory to study systems with variable effective mass and dielectric constant is employed. Our results show that high/low spin configurations can be switched by appropriate changes in the quantum dot embedding environment and suggest the use of the quantum dot spin as a sensor of the dielectric response of medi

Spatial and temporal stability of weed patches in cereal fields under direct drilling and harrow tillage

The adoption of conservation agriculture (CA) techniques by farmers is changing the dynamics of weed communities in cereal fields and so potentially their spatial distribution. These changes can challenge the use of site-specific weed control, which is based on the accurate location of weed patches for spraying. We studied the effect of two types of CA (direct drilling and harrow-tilled to 20 cm) on weed patches in a three-year survey in four direct-drilled and three harrow-tilled commercial fields in Catalonia (North-eastern Spain). The area of the ground covered by weeds (hereafter called “weed cover”) was estimated at 96 to 122 points measured in each year in each field, in 50 cm × 50 cm quadrats placed in a 10 m × 10 m grid in spring. Bromus diandrus, Lolium rigidum, and Papaver rhoeas were the main weed species. The weed cover and degree of aggregation for all species varied both between and within fields, regardless of the kind of tillage. Under both forms of soil management all three were aggregated in elongated patterns in the direction of traffic. Bromus was generally more aggregated than Lolium, and both were more aggregated than Papaver. Patches were stable over time for only two harrow-tilled fields with Lolium and one direct-drilled field with Bromus, but not in the other fields. Spatial stability of the weeds was more pronounced in the direction of traffic. Herbicide applications, crop rotation, and traffic seem to affect weed populations strongly within fields, regardless of the soil management. We conclude that site-specific herbicides can be applied to control these species because they are aggregated, although the patches would have to be identified afresh in each season.This research was funded by the Spanish National Program (project: AGL2010-22084-C02-0). A.E.M. was funded by the Institute Strategic Programme (ISP) grants, “Soils to Nutrition” (S2N) grant number BBS/E/C/000I0330, and the joint Natural Environment Research Council (NERC) and Biotechnology and Biological Sciences Research Council (BBSRC) ISP grant “Achieving Sustainable Agricultural Systems” (ASSIST) grant number BBS/E/C/000I0100, using facilities funded by the BBSRC

High pressure oxidation of dimethoxymethane

The oxidation of dimethoxymethane (DMM) has been studied under a wide range of temperatures (373-1073 K), pressures (20-60 bar) and air excess ratios (¿ = 0.7, 1 and 20), from both experimental and modeling points of view. Experimental results have been interpreted and analyzed in terms of a detailed gas-phase chemical kinetic mechanism for describing the DMM oxidation. The results show that the DMM oxidation regime for 20, 40 and 60 bar is very similar for both reducing and stoichiometric conditions. For oxidizing conditions, a plateau in the DMM, CO and CO2 concentration profiles as a function of the temperature can be observed. This zone seems to be associated with the peroxy intermediate, CH3OCH2O2, whose formation and consumption reactions appear to be important for the description of DMM conversion under high pressure and high oxygen concentration conditions

Pyranylidene/trifluoromethylbenzoic acid-based chromophores for dye-sensitized solar cells

The synthesis and photovoltaic study of five dyes based on 4H-pyranylidene moiety as donor moiety is reported. A thiophene unit conjugated with/without an ethynyl bond acts as the p-relay and benzoic acid as the anchor group with/without a trifluoromethyl group. Their electrochemical and optical properties are analyzed by using a joint experimental and theoretical approach. The presence of the trifluoromethyl group leads to an enhancement of the molar extinction coefficient, being slightly when a hexyl chain is introduced in the thiophene ring, but does not modify the oxidation potential. For the preparation of derived solar cells an antiaggregant is essential in all cases. The photovoltaic performance is sensitive to the structural modification of the dye: the CF3 group and the hexyl chain of the thiophene spacer were shown to improve the efficiency. The lack of a triple bond in the p-spacer involves a lower photovoltaic efficiency, and the trifluoromethyl group leads to a lower dye-load, but a decrease of the recombination processes. These results are in accordance with the electrochemistry impedance spectroscopy studies carried out. Moreover, the organic dyes have been also tested with a fluorescent lamp (indoor conditions), leading to an increase of the efficiency, reaching a 36% for the best dye. © 2022 The Author

Organocomplejos iónicos de talio (III)

The perchlorate group in (Cr,Cl.,)2Tl (CIO4) is readily displaced by several neutral ligands leadíng to the isolation of several cationic organorhallium (III) complexes; j [TI (CcClOjjaLa } (C10«)2 (L = bipy, o-fen), [TI {C^CU),U] CIO. (L = OPPha, OAsPhs) and [TI (CoClj)» (OPPhs)] ClOj have been obtained in this way. The anionic organorhallium (III) complex (EtiN) [TII2 (CaCl5)2] has been prepared by adding EtjNI to a methanolic solution of (CGCIS)! TU. All the compounds have been studied by means of infrared spectroscopy and conductivity measurements