Cartier and Weil Divisors on Varieties with Quotient Singularities

The main goal of this paper is to show that the notions of Weil and Cartier $\mathbb{Q}$-divisors coincide for $V$-manifolds and give a procedure to express a rational Weil divisor as a rational Cartier divisor. The theory is illustrated on weighted projective spaces and weighted blow-ups.Comment: 16 page

Numerical explicit analysis of hole flanging by single-stage incremental forming

The use of Single-Point Incremental Forming (SPIF) technology in hole flanging operations using multi-stages strategies have been widely studied in the last few years. However, these strategies are very time-consuming, limiting its industrial application.In a very recent work of the authors, the capability of SPIF process to successfully perform hole-flanges using a single-stage strategy has been experimentally investigated. The aim of the present work is to develop a numerical model of this process to beable to predict the sheet failure as a function of the size of the pre-cut hole. The numerical results are compared and discussed in the light of experimental tests over AA7075-O metal sheets with 1.6mm thickness.Ministerio de Economía y Competitividad DPI2015-64047-

Fingerprinting Chamaesiphon populations as an approach toassess the quality of running waters

"This is the peer reviewed version of the following article: Loza, V.; Morales, A.; Perona, E. and Muñoz-Martín, M. A."Fingerprinting Chamaesiphon populations as an approach toassess the quality of running waters" River Research and Applications 34 (2018): 595-605 which has been published in final form at https://doi.org/10.1002/rra.3277. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."Cyanobacterial communities are highly diverse in freshwaters and respond rapidly tochanging environments. Previous studies have highlighted variations in the structureand composition of epilithic cyanobacterial communities in response to eutrophica-tion in watercourses. In the present study, changes in benthic cyanobacterial commu-nities from Guadalix River (Spain) biofilms were examined using temperature‐gradientgel electrophoresis (TGGE) in conjunction with microscopic examination of field‐fixedsamples, focusing on populations of one of the dominant cyanobacteria:Chamaesiphon. Environmental characteristics were determined in order to character-ize the trophic status of the sampling sites. The presence of cyanobacteria in the riverwas determined from complex TGGE patterns, band extraction, and subsequentsequencing of 16S rDNA gene fragments. The microscopic observations revealed thatthe unicellular genus Chamaesiphon and the filamentous genus Phormidium were dom-inant in the studied locations. Within the 2 genera, 4 Chamaesiphon populations wereidentified (Chamaesiphon fuscus, Chamaesiphon starmachii, Chamaesiphon subglobosus ,and Chamaesiphon polymorphus) and Phormidium was represented at the samplingsites by the Phormidium autumnale morphotype. TGGE banding patterns differedamong samplings sites as a function of water quality. The genetic analysis revealed4 phylotypes within the genus Chamaesiphon and 1 phylotype within the classicP. autumnale clade. Chamaesiphon phylotypes were not equally distributed in all thesampling locations. Some phylotypes were related to low nutrient concentrations,while others were associated with eutrophic conditions. Our results support the useof fingerprints of Chamaesiphon populations obtained by TGGE to examine changesin water quality.This work was supported by Grant CGL2013‐44870‐R from the Ministerio de Economía y Competitividad, Spai

Delta invariant of curves on rational surfaces I. An analytic approach

We prove that if (C, 0) is a reduced curve germ on a rational surface singularity (X, 0) then its delta invariant can be recovered by a concrete expression associated with the embedded topological type of the pair C X. Furthermore, we also identify it with another (a priori) embedded analytic invariant, which is motivated by the theory of adjoint ideals. Finally, we connect our formulae with the local correction term at singular points of the global Riemann-Roch formula, valid for projective normal surfaces, introduced by Blache

Sibling competition and not maternal allocation drives differential offspring feeding in a sexually size-dimorphic bird

Sex allocation models still fail to predict the complex sex ratio patterns in broods of vertebrates. A major problem when studying mother–brood interactions is the difficulty in disentangling hypotheses involving maternal preferences from processes that do not imply maternal manipulation. We studied maternal resource allocation in mixed-sex, same-sex and single-chick broods in the great bustard, Otis tarda. Females normally rear a single chick, and previous work has shown that maternal investment influences male more than female breeding success. Therefore, mothers of two-chick broods were assumed to be in good condition and candidates to show a preference for sons. Results showed that male chicks of mixed-sex broods remained close to the mother for twice as long as their sisters, and received double the number of maternal feedings. However, sex differences in maternal feeding rate disappeared when considering only simultaneous begging approaches from both siblings. Proximity to the mother and its interaction with begging approach intensity were the factors determining the higher begging success of male chicks. In single-chick broods, females did not receive fewer maternal feedings than males. Overall, our results suggest that female chicks of mixed-sex broods become outcompeted by their larger brothers, which remain close to the mother much longer, preventing their sisters from taking a larger share of maternal feedings. We conclude that mothers do not show a preference for feeding male over female chicks, and that the sex differences in feeding rate are determined by the higher food requirements of male chicks due to their sexually selected, much faster growth rates. The higher mortality of females in mixed-sex broods contrasts with the pattern of male-biased mortality typical in this species, and supports our interpretation of an asymmetric competitive ability of male offspring as the mechanism responsible for the sex bias in maternal expenditure.This work was supported by the Dirección General de Investigación Científica y Técnica (projects PB91-0081 and PB94-0068, with contributions from other projects awarded to J.C.A. for marking and radiotracking birds 1987–2013); the Instituto Nacional para la Conservación de la Naturaleza; and the Junta de Castilla y León. During the study, E.M. benefitted from a predoctoral fellowship of the Dirección General de Investigación Científica y Técnica. Research by J.C.A. and J.A.A. was supported by project CGL2012-36345 during the writing of the pape

Migration Patterns in Male Great Bustards (Otis tarda)

5 paginas, 1 figura y 1 tableThe Great Bustard (Otis tarda) is distributed from Iberia and Morocco in the west to China in the east and has been considered sedentary in all but the northern and eastern parts of its range (Gewalt 1959, Glutz et al. 1973, Cramp and Simmons 1980). However, some studies have reported seasonal changes in population numbers in different areas in the Iberian Peninsula (Hidalgo and Carranza 1990, Alonso et al. 1995), suggesting that the species is a partial migrant (sensu Terrill and Able 1988) in this region. We describe seasonal movements of marked adult male Great Bustards and discuss observed patterns in relation to the following questions: (1) Do migratory males display interannual fidelity to breeding and postbreeding areas? (2) Do males travel significantly farther than females in their seasonal movements? We also suggest several hypotheses that could explain patterns of partial and differential migration in male Great Bustards.This study is a contribution to DGICYT-project PB94–0068.Peer reviewe

Evaluation of captive breeding as a method to conserve threatened Great Bustard populations.

6 paginas y 1 tableThe recent Great Bustard Action Plan summarizes de main recommended lines of action to preserve current populations and their habitats in Europe. Among others, captive breeding is mentioned as a method to save clutches found in the field whose hatching success probability is suspected to be low for any reason. Birds hatched from these clutches have been used to either build up small captive-breeding flocks that ensure preservation of the genetic pool of seriously threatened populations once these may be extinct, or to be released into the natural populations as juveniles. In this paper we evaluate the viability of captive breeding in the light of new results of a recent study of juvenile Great Bustards during their maternal dependence period, family break-up and dispersal. The few data available on survival of captive-bred young after being released suggest that they suffer a high mortality, probably due to the lack of the experience acquired in natural conditions from their mothers. The negative effects of imprinting by their human keepers, particularly in relation with display and mating, has not been sufficiently investigated. These and other aspects make captive breeding questionable as an effective method, as compared with habitat protection measures.PB94-0068 of the Dirección General de Investigacion Cientifica y TecnicaPeer reviewe

Migration Patterns in Male Great Bustards (Otis tarda)

5 paginas, 1 figura y 1 tableThe Great Bustard (Otis tarda) is distributed from Iberia and Morocco in the west to China in the east and has been considered sedentary in all but the northern and eastern parts of its range (Gewalt 1959, Glutz et al. 1973, Cramp and Simmons 1980). However, some studies have reported seasonal changes in population numbers in different areas in the Iberian Peninsula (Hidalgo and Carranza 1990, Alonso et al. 1995), suggesting that the species is a partial migrant (sensu Terrill and Able 1988) in this region. We describe seasonal movements of marked adult male Great Bustards and discuss observed patterns in relation to the following questions: (1) Do migratory males display interannual fidelity to breeding and postbreeding areas? (2) Do males travel significantly farther than females in their seasonal movements? We also suggest several hypotheses that could explain patterns of partial and differential migration in male Great Bustards.This study is a contribution to DGICYT-project PB94–0068.Peer reviewe