278 research outputs found

    Minimal surfaces and particles in 3-manifolds

    Full text link
    We use minimal (or CMC) surfaces to describe 3-dimensional hyperbolic, anti-de Sitter, de Sitter or Minkowski manifolds. We consider whether these manifolds admit ``nice'' foliations and explicit metrics, and whether the space of these metrics has a simple description in terms of Teichm\"uller theory. In the hyperbolic settings both questions have positive answers for a certain subset of the quasi-Fuchsian manifolds: those containing a closed surface with principal curvatures at most 1. We show that this subset is parameterized by an open domain of the cotangent bundle of Teichm\"uller space. These results are extended to ``quasi-Fuchsian'' manifolds with conical singularities along infinite lines, known in the physics literature as ``massive, spin-less particles''. Things work better for globally hyperbolic anti-de Sitter manifolds: the parameterization by the cotangent of Teichm\"uller space works for all manifolds. There is another description of this moduli space as the product two copies of Teichm\"uller space due to Mess. Using the maximal surface description, we propose a new parameterization by two copies of Teichm\"uller space, alternative to that of Mess, and extend all the results to manifolds with conical singularities along time-like lines. Similar results are obtained for de Sitter or Minkowski manifolds. Finally, for all four settings, we show that the symplectic form on the moduli space of 3-manifolds that comes from parameterization by the cotangent bundle of Teichm\"uller space is the same as the 3-dimensional gravity one.Comment: 53 pages, no figure. v2: typos corrected and refs adde

    Conformal functionalization of cotton fibers via isoreticular expansion of UiO-66 metal-organic frameworks

    Get PDF
    We report on the growing of metal-organic frameworks that are isoreticular and isostructural to UiO-66, onto cotton fabrics via a solvothermal method. Four different metal-organic frameworks (MOFs) (UiO-66, UiO-66-NH2, UiO-66-NDC, and UiO-67) were chosen as a case study. The presence of the UiO-based MOFs was confirmed through X-ray diffraction and Scanning Electron Microscopy. We used thermogravimetric analysis to quantify the amount of the MOF loading, which ranged from 0.8% to 2.6% m/m. We also explored the role of ligand size, growth time, and reaction temperature on the conformal coating of cotton fibers with these Zr-based MOFs. Cotton fabrics coated with Zr-based MOFs can find applications as selective filters in aggressive environments due to their enhanced chemical and thermal stabilities.Fil: Schelling, Marion. Cornell University; Estados UnidosFil: Otal, Eugenio Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Shinshu University. Faculty of Textile Science and Technology. Department of Chemistry and Materials; JapónFil: Kim, Manuela Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Shinshu University. Faculty of Textile Science and Technology. Department of Chemistry and Materials; JapónFil: Hinestroza, Juan P.. Cornell University; Estados Unido

    Woody encroachment and soil carbon stocks in subalpine areas in the Central Spanish Pyrenees

    Get PDF
    Woody encroachment has been an ongoing process in the subalpine belt of Mediterranean mountains, after land abandonment, the disappearance of the transhumant system and the decrease of the livestock number. The main objectives of this study were: (i) to identify land use/land cover (LULC) changes from 1956 to 2015, and (ii) to investigate the effects of LULC changes in physical and chemical soil properties and soil organic carbon (SOC) and nitrogen (N) stocks. It is hypothesized that woody encroachment in the subalpine belt may lead to significant changes in soil properties, and will generate an increase in the SOC stocks. A land use gradient was identified in the subalpine belt of the Central Spanish Pyrenees: (i) subalpine grasslands, (ii) shrublands, (iii) young forests, and (iv) old forests. Mineral soil samples were collected every 10 cm, down to 40 cm, at three points per each LULC and a total of 48 samples were analyzed. The results showed that (i) woody encroachment has occurred from 1956 to 2015 due to the expansion of coniferous forests and shrublands (at the expense of grasslands), (ii) land cover and soil depth had significant effects on soil properties (except for pH), being larger in the uppermost 0–10 cm depth, (iii) SOC and N contents and stocks were higher in the grassland sites, and (iv) the woody encroachment process initially produced a decrease in the SOC stocks (shrublands), but no differences were observed considering the complete soil profile between grasslands and young and old forests. Further studies, describing SOC stabilization and quantifying above-ground carbon (shrub and tree biomass) are required

    Liver Resection after Downstaging Hepatocellular Carcinoma with Sorafenib

    Get PDF
    Background. Sorafenib is a molecular-targeted therapy used in palliative treatment of advanced hepatocellular carcinoma in Child A patients. Aims. To address the question of sorafenib as neoadjuvant treatment. Methods. We describe the cases of 2 patients who had surgery after sorafenib. Results. The patients had a large hepatocellular carcinoma in the right liver with venous neoplastic thrombi (1 in the right portal branch, 1 in the right hepatic vein). After 9 months of sorafenib, reassessment showed that tumours had decreased in size with a necrotic component. A right hepatectomy with thrombectomy was performed, and histopathology showed 35% to 60% necrosis. One patient had a recurrence after 6 months and had another liver resection; they are both recurrence-free since then. Conclusion. Sorafenib can downstage hepatocellular carcinoma and thus could represent a bridge to surgery. It may be possible to select patients in good general condition with partial regression of the tumour with sorafenib for a treatment in a curative intent

    Global study of is6110 in a successful mycobacterium tuberculosis strain: Clues for deciphering its behavior and for its rapid detection

    Get PDF
    The Mycobacterium tuberculosis insertion sequence IS6110, besides being a very useful tool in molecular epidemiology, seems to have an impact on the biology of bacilli. In the present work, we mapped the 12 points of insertion of IS6110 in the genome of a successful strain named M. tuberculosis Zaragoza (which has been referred to as the MTZ strain). This strain, belonging to principal genetic group 3, caused a large unsuspected tuberculosis outbreak involving 85 patients in Zaragoza, Spain, in 2001 to 2004. The mapping of the points of insertion of IS6110 in the genome of the Zaragoza strain offers clues for a better understanding of the adaptability and virulence of M. tuberculosis. Surprisingly, the presence of one copy of IS6110 was found in Rv2286c, as was recently described for a successful Beijing sublineage. As a result of this analysis, a rapid method for detecting this particular M. tuberculosis strain has been designed

    Dental evidence of textile-related task activities in the Bronze Age site of Laderas del Castillo (Alicante, Spain)

    Get PDF
    The burial 7 from the Argaric site of Laderas del Castillo (Alicante, Spain), dating from the 2nd millennium BC, included a skeleton associated with a carinated vessel indicative of social recognition. Anthropological and DNAbased methods were combined to determine that the individual corresponds to a young female. Macro- and scanning microscopic analyses revealed morphologically uniform labial notches with smooth and polished enamel on maxillary central incisors, which suggest tooth-tool use involving craft tasks. Plant fibers entrapped in dental calculus suggest that the individual was involved in textile and craft production, most likely working with flax or hemp. These findings provide new and direct insights into the use of teeth as tools related to crafts involving threads and are valuable for assessing the social division of labor within the Argaric prehistoric populations from Southeastern Iberia

    The lack of the TetR-like repressor gene BCG_2177c (Rv2160A) may help mycobacteria overcome intracellular redox stress and survive longer inside macrophages when surrounded by a lipid environment

    Get PDF
    Mycobacteria, like other microorganisms, survive under different environmental variations by expressing an efficient adaptive response, oriented by regulatory elements, such as transcriptional repressors of the TetR family. These repressors in mycobacteria also appear to be related to cholesterol metabolism. In this study, we have evaluated the effect of a fatty acid (oleic–palmitic–stearic)/cholesterol mixture on some phenotypic and genotypic characteristics of a tetR-mutant strain (BCG_2177c mutated gene) of M. bovis BCG, a homologous of Rv2160A of M. tuberculosis. In order to accomplish this, we have analyzed the global gene expression of this strain by RNA-seq and evaluated its neutral-lipid storage capacity and potential to infect macrophages. We have also determined the macrophage response by measuring some pro- and anti-inflammatory cytokine expressions. In comparison with wild-type microorganisms, we showed that the mutation in the BCG_2177c gene did not affect the growth of M. bovis BCG in the presence of lipids but it probably modified the structure/composition of its cell envelope. Compared to with dextrose, an overexpression of the transcriptome of the wild-type and mutant strains was observed when these mycobacteria were cultured in lipids, mainly at the exponential phase. Twelve putative intracellular redox balance maintenance genes and four others coding for putative transcriptional factors (including WhiB6 and three TetR-like) were the main elements repeatedly overexpressed when cultured in the presence of lipids. These genes belonged to the central part of what we called the “genetic lipid signature” for M. bovis BCG. We have also found that all these mycobacteria genotypic changes affected the outcome of BCG-infected macrophages, being the mutant strain most adapted to persist longer inside the host. This high persistence result was also confirmed when mutant-infected macrophages showed overexpression of the anti-inflammatory cytokine TGF-ß versus pro-inflammatory cytokines. In summary, the lack of this TetR-like repressor expression, within a lipid environment, may help mycobacteria overcome intracellular redox stress and survive longer inside their host

    International grassland communals (facerías) in the Pyrennees: history, current situation and future prospects

    Get PDF
    Ponencia presentada a la 51 Reunión Científica de la SEEP celebrada en la Escuela Superior de Ingenieros Agrónomos de la Universidad Pública de Navarra entre el 14 y el 18 de mayo de 2012.La ponencia define el concepto de facería internacional pirenaica y realiza en sus primeros apartados una síntesis histórica de sus orígenes y de su evolución a lo largo de sus ocho siglos de existencia. Se realiza posteriormente una recopilación de las facerías existentes en el Pirineo y de su estado actual de vigencia y se comentan los aspectos más peculiares y particulares de las mismas. En la segunda parte de la ponencia se describe el nuevo marco político-jurídico de las facerías internacionales pirenaicas, se detalla un ejemplo de evolución de una facería actual, plenamente vigente y acorde a los tiempos actuales, la facería de Aezkoa-Cize, y se reflexiona sobre los retos y posibilidades a futuro de estos acuerdos internacionales de origen ancestral.Facería is a land of grass in the boundaries of two valleys, which is used in common. This presentation defines the concept of international grassland communal in the Pyrenees and describes its ancient origin and its evolution along the last eight centuries. Further, a compilation of international grassland communals along the Pyrenees is done, describing their main traits and particular characteristics and indicating their degree of relevance nowadays. The second part of the manuscript is devoted to analyze the current, political and legal, framework of these entities, and to describe the evolution of a modernized facería, that involves the Spanish valley of Aezkoa and the French valley of Cize. Eventually, we reflect on the challenges and on the future prospects of these international grassland communals in an European context
    corecore