2,018 research outputs found

    On rational cuspidal projective plane curves

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    In 2002, L. Nicolaescu and the fourth author formulated a very general conjecture which relates the geometric genus of a Gorenstein surface singularity with rational homology sphere link with the Seiberg--Witten invariant (or one of its candidates) of the link. Recently, the last three authors found some counterexamples using superisolated singularities. The theory of superisolated hypersurface singularities with rational homology sphere link is equivalent with the theory of rational cuspidal projective plane curves. In the case when the corresponding curve has only one singular point one knows no counterexample. In fact, in this case the above Seiberg--Witten conjecture led us to a very interesting and deep set of `compatibility properties' of these curves (generalising the Seiberg--Witten invariant conjecture, but sitting deeply in algebraic geometry) which seems to generalise some other famous conjectures and properties as well (for example, the Noether--Nagata or the log Bogomolov--Miyaoka--Yau inequalities). Namely, we provide a set of `compatibility conditions' which conjecturally is satisfied by a local embedded topological type of a germ of plane curve singularity and an integer dd if and only if the germ can be realized as the unique singular point of a rational unicuspidal projective plane curve of degree dd. The conjectured compatibility properties have a weaker version too, valid for any rational cuspidal curve with more than one singular point. The goal of the present article is to formulate these conjectured properties, and to verify them in all the situations when the logarithmic Kodaira dimension of the complement of the corresponding plane curves is strictly less than 2

    Number needed to freeze: cumulative live birth rate after fertility preservation in women with endometriosis

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    Research question: How does the number of oocytes used affect the cumulative live birth rate in endometriosis patients who had their oocytes vitrified for fertility preservation (FP)? Design: Retrospective observational study including data from 485 women with endometriosis who underwent FP from January 2007 to July 2018. Survival curves and Kaplan-Meier plots were used to analyse the cumulative live birth rate (CLBR) according to the number of vitrified oocytes used. Data were stratified according to age, stage of the disease and ovarian surgery prior to FP (operated vs. non-operated). Endometriosis curves were compared to plots developed using elective fertility preservation (EFP) patients as control group. Log-rank, Breslow and Tarone-Ware tests were used to compare the survival curves. Results: The CLBR increased as the number of oocytes used per patient rose, reaching 89.5% (95% CI=80.0-99.1) using 22 oocytes. Higher outcomes were observed in young women (≤35 y. vs. >35 y). In the younger group, the CLBR was 95.4% (95% CI=87.2-103.6) using ~20 oocytes vs. 79.6% (95% CI=58.1-101.1) in older women (P<0.05). No statistical differences were observed in overall calculations and according to age when the CLBR was compared between operated and non-operated women (NS). Comparable outcomes were also observed in stages I-II vs. III-IV (NS). The mean age was higher in EFP patients (37.2 ± 4.9 vs. 35.7 ± 3.7; P<0.05). The outcome was better in the endometriosis group as compared to EFP (P<0.05): a CLBR of 89.5% (80.0-99.1) vs. 59.9% (51.4-68.6) when 22 oocytes were used (P<0.05). However, the difference was milder when fewer oocytes were used in both groups. When comparisons were made between age-matching groups, no statistical differences were observed (NS). Conclusion: The probability of live birth increases as the number of oocytes used rises in patients with endometriosis, but better outcomes were observed among young women. Neither the stage of the disease nor prior surgical excision of ovarian endometrioma were related to success. No statistical differences in age matching groups were observed when comparing to EFP patients. The information provided herein may be of interest to both patients and treating physicians for counselling purposes

    Change detection of buildings from satellite imagery and lidar data

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    Geospatial objects change over time and this necessitates periodic updating of the cartography that represents them. Currently, this updating is done manually, by interpreting aerial photographs, but this is an expensive and time-consuming process. While several kinds of geospatial objects are recognized, this article focuses on buildings. Specifically, we propose a novel automatic approach for detecting buildings that uses satellite imagery and laser scanner data as a tool for updating buildings for a vector geospatial database. We apply the support vector machine (SVM) classification algorithm to a joint satellite and laser data set for the extraction of buildings. SVM training is automatically carried out from the vector geospatial database. For visualization purposes, the changes are presented using a variation of the traffic-light map. The different colours assist human operators in performing the final cartographic updating. Most of the important changes were detected by the proposed method. The method not only detects changes, but also identifies inaccuracies in the cartography of the vector database. Small houses and low buildings surrounded by high trees present significant problems with regard to automatic detection compared to large houses and taller buildings. In addition to visual evaluation, this study was checked for completeness and correctness using numerical evaluation and receiver operating characteristic curves. The high values obtained for these parameters confirmed the efficacy of the method

    Particle Patterning on Lithium Niobate waveguides via photovoltaic tweezers

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    Successful micro and nano-particle patterning on iron doped lithium niobate waveguides using photovoltaic fields is reported. This technique previously used in bulk crystals is here applied to waveguide configuration. Well defined particle patterns are obtained using two types of planar waveguides (by proton exchanged and swift heavy ion irradiation) and metallic and dielectric neutral particles. The use of waveguide configuration has allowed a reduction of the light exposure time until 3 s, two orders of magnitude smaller than typical values used in bulk

    On rational cuspidal plane curves, open surfaces and local singularities

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    Let C be an irreducible projective plane curve in the complex projective space P(2). The classification of such curves, up to the action of the automorphism group PGL(3, C) on P(2), is a very difficult open problem with many interesting connections. The main goal is to determine, for a given d, whether there exists a projective plane curve of degree d having a fixed number of singularities of given topological type. In this note we are mainly interested in the case when C is a rational curve. The aim of this article is to present some of the old conjectures and related problems, and to complete them with some results and new conjectures from the recent work of the authors

    Autoimmune/inflammatory syndrome induced by adjuvants: a review

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    The autoimmune/inflammatory syndrome induced by adjuvants (ASIA) includes several autoimmune conditions and phenomena that occur after exposure to substances with adjuvant activity. The spectrum of the disease is heterogeneous with respect to the clinical presentation as well as the severity of the clinical manifestations. Different substances and medical devices with adjuvant activity are currently known, such as vaccines, oils, silicones, mineral salts, lipopolysaccharides, peptidoglycans, among others. These adjuvants are immunological molecules that function through potentiation of antigen-specific immune responses. Thus, the etiopathogenesis of ASIA syndrome involves a multifactorial interaction between environmental factors and genetic predisposition, and secondary activation of the adaptive and innate arms of the immune system through various mechanisms. Although in some reported cases the ASIA syndrome improves considerably when removing the implants, there are no conclusive results for the clinical benefit of removing the implants, so it is necessary to carry out further basic, clinical and surgical investigations in order to determine the best therapeutic decision

    Effect of metal loading on the CO2 methanation: A comparison between alumina supported Ni and Ru catalysts

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    The hydrogenation of CO2 into CH4 from H2 produced by renewable energy is considered an interesting alternative in order to promote the development of such green energies. In the present work, the effect of Ni and Ru loadings on the catalytic performance of alumina-supported catalysts is studied for CO2 methanation reaction. All catalysts were prepared by wetness incipient impregnation, characterized by several techniques (N2-physisorption, CO2-TPD, XRD, H2-chemisorption, XPS and H2-TPR) and evaluated for CO2 methanation in a fixed bed reactor at GHSV=10,000 h−1 and W/FCO2 0 = 4.7 (g cat.) h mol−1. Characterization results showed that addition of increasing loadings of Ni and Ru lead to the formation of both CO2 adsorption and H2 dissociation active sites, which are necessary to carry out CO2 hydrogenation into methane. Easily reducible ruthenium was dispersed on γ-Al2O3 in form of large agglomerates, whereas Ni was better dispersed presenting a great interaction with the support. 12% Ni and 4% Ru resulted to be the optimal contents providing metal surfaces of 5.1 and 0.6m2 g−1, T50 values of 340 and 310 °C and activity being quite stable for 24 h-on-stream. In terms of turnover frequency (TOF), 4%Ru/Al2O3 catalyst was quite more efficient than 12%Ni/Al2O3, probably due to a greater ability of ruthenium to dissociate hydrogen. The apparent activation energies for alumina supported Ni and Ru were 129 and 84 kJ mol−1, respectively.The support from the Economy and Competitiveness Spanish Ministry (CTQ2015-67597-C2-1-R and CTQ2015-67597-C2-2-R MINECO-FEDER), the Basque Government (IT657-13 and IT1297-19) and the SGIker (Analytical Services) at the University of the Basque Country are acknowledged. One of the authors (AQ) also acknowledges University of the Basque Country by his PhD grant (PIF-15/351)

    Ni/LnOx catalysts (Ln = La, Ce or Pr) for CO2 methanation

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    The effect of the LnOx support has been studied for Ni‐based CO2 methanation catalysts. 10 wt. % nickel catalysts with LaOx, CeO2 and PrOx supports have been prepared, characterized by N2 adsorption, XRD, XRF, TG‐MS (N2‐TPD and H2‐TPR) and XPS, and have been tested for CO2 methanation. The catalytic activity follows the trend Ni/CeO2 > Ni/PrOx >> Ni/LaOx, all catalysts being very selective towards CH4 formation. The activity depends both on the nature of the catalytic active sites and on the stability of the surface CO2 and H2O species. Ni/CeO2 is the most active catalyst because (i) the Ni2+‐ceria interaction leads to the formation of the highest population of active sites for CO2 dissociation, (ii) the reduced Ni0 sites where H2 dissociation takes place are the most electronegative and active, and (iii) the stability of surface CO2 and H2O species is lowest. Ni/LaOx achieves lower activity because of the strong chemisorption of H2O and CO2, which poison the catalyst surface, and because this support is not able to promote the formation of highly active sites for CO2 and H2 dissociation. The behavior of Ni/PrOx is intermediate, being slightly lower to that of Ni/CeO2 because the formation of active sites is not so efficient and because the stability of chemisorbed CO2 is slightly higher.The authors thank the financial support of Basque Government (Consolidated Group IT657-13), Spanish Ministry of Economy and Competitiveness (Projects CTQ2015-67597-C2-1-R and CTQ2015-67597-C2-2-R), and the EU (FEDER funding). ADQ thanks the Spanish Ministry of Education, Culture and Sports (grant FPU14/01178) and AQ the University of the Basque Country (grant PIF15/351)

    Relación entre variables del forófito y la riqueza de epífitas vasculares en los Pantanos de Centla, Tabasco, México

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    Background and Aims: Vascular epiphytes are rare elements of mangrove-dominated forests because sea salinity causes extreme conditions that difficult their establishment. In southern Mexico, most of the studies about the relationships between epiphytes and phorophytes have been carried out in montane forests, while the mangrove forests have received little attention. Our aim was to analyze the relationships between epiphytic species richness and the phorophyte characteristics of Rhizophora mangle, an endangered species under the NOM-059-SEMARNAT- 2010, in the “Pantanos de Centla” Biosphere Reserve located in the north-east of the state of Tabasco.Methods: The relation between species richness of epiphytes and several variables of the phorophytes, such as the aerial root coverage, diameter at breast height (DBH) and height, was evaluated using linear regression models. In addition, phorophytes were divided into five vertical zones to analyze the vertical distribution of the epiphytes using the Sørensen and Margalef indexes.Key results: Seventeen species of epiphytes were recorded. Orchidaceae and Bromeliaceae were the families with the highest species richness (six each). The most representative genus was Tillandsia (Bromeliaceae) with five species. The epiphytic species richness was significantly correlated with phorophyte aerial root coverage and DBH. The phorophyte zones I and III were the most similar because they shared 47% of all recorded species. The zone I (aerial roots) showed the highest epiphyte species richness. In the zone V (outer portion of the canopy) only Selenicereus testudo (Cactaceae) was registered, a species that was found in all five zones of the phorophyte. The mangrove area studied has a relatively high epiphyte richness in spite of the high salinity present in its flooded habitat.Conclusions: Epiphytic species richness was determined by the variation in size of the phorophytes. The aerial roots of R. mangle are an additional niche for the colonization of epiphytes and not just a supporting structure for the unstable soil of the mangrove ecosystem.Antecedentes y Objetivos: Las epífitas vasculares son elementos poco comunes en manglares debido a que la salinidad del agua de mar impone condiciones extremas que dificultan su establecimiento. En el sur de México se han realizado estudios sobre las relaciones epífitas-forófito, principalmente en bosques montanos, pero hay pocos trabajos enfocados en los manglares. El objetivo de este trabajo fue analizar las relaciones entre la riqueza de epífitas y las características de los forófitos de Rhizophora mangle, especie amenazada de acuerdo a la NOM-059-SEMARNAT-2010, en la Reserva de la Biosfera “Pantanos de Centla”, ubicada en el noreste del estado de Tabasco.Métodos: Se evaluó la relación entre la riqueza de epífitas y algunas variables de los forófitos, como la altura, el diámetro a la altura del pecho (DAP) y la cobertura de raíces aéreas, mediante modelos de regresión lineal. Además, los forófitos se dividieron en cinco zonas verticales para analizar la distribución vertical de las epífitas aplicando los índices de Sørensen y Margalef.Resultados clave: Se registraron 17 especies de epífitas. Orchidaceae y Bromeliaceae fueron las familias con mayor riqueza (seis especies cada una). El género más representativo fue Tillandsia (Bromeliaceae) con cinco especies. La riqueza de epífitas estuvo significativamente relacionada con la cobertura de raíces aéreas y el DAP de los forófitos. Las zonas I y III de los forófitos fueron las más similares ya que compartieron 47% del total de las especies registradas. La zona I (raíces aéreas) fue la más rica en especies de epífitas. En la zona V (parte exterior de la copa) solo se encontró a Selenicereus testudo (Cactaceae), especie también hallada en el resto de las zonas. El área de manglar estudiado presenta una riqueza relativamente alta de epífitas pese a la alta salinidad presente en su hábitat inundado.Conclusiones: La variación de los tamaños de los forófitos determinó la riqueza de epífitas. Las raíces aéreas de R. mangle son un nicho adicional para la colonización de epífitas y no solamente sirven como soporte al suelo inestable del ecosistema de manglar
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