4,010 research outputs found

    Characterizing normal crossing hypersurfaces

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    The objective of this article is to give an effective algebraic characterization of normal crossing hypersurfaces in complex manifolds. It is shown that a hypersurface has normal crossings if and only if it is a free divisor, has a radical Jacobian ideal and a smooth normalization. Using K. Saito's theory of free divisors, also a characterization in terms of logarithmic differential forms and vector fields is found and and finally another one in terms of the logarithmic residue using recent results of M. Granger and M. Schulze.Comment: v2: typos fixed, final version to appear in Math. Ann.; 24 pages, 2 figure

    Refractory Coats’ Disease of Adult Onset

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    Purpose: We present the case of an 18-year-old Caucasian male with a unilateral macular star and retinal vascular anomalies compatible with adult onset Coats’ disease. Methods: Diagnosis was based on fundoscopic, fluorescein angiography and optical coherence tomography findings. Results: The patient presented to our emergency department with complaints of low vision in his left eye (LE) detected 10 days before. The best-corrected visual acuity in the LE was 20/50. Fundoscopy of the LE evidenced a complete macular star. Optical coherence tomography showed increased retinal thickness, infiltration of the retinal wall, and detachment of the neuroepithelium. Angiography revealed no appreciable diffusion in the macula. Above the superior temporal (ST) arcade, anomalies in the retinal vasculature were found, with interruption of the peripheral vessels and vessels which were ‘sausage’-like. After 1 month, the LE vision evolved to hand movements. Laser photocoagulation was performed in the ST quadrant. Intravitreal injection of bevacizumab 1.25 mg/0.05 ml and photodynamic therapy were performed without any significant changes, progression of ST serous detachment of the neuroepithelium, and finally progression to macular fibrosis. Discussion: Coats’ disease is usually diagnosed in childhood, but rare cases may occur in adults. Those cases usually have a more indolent course which was not observed in our patient. When there is macular involvement, prognosis is more guarded, despite treatment

    Linking forest cover, soil erosion and mire hydrology to late-Holocene human activity and climate in NW Spain

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    This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 License (http://www.creativecommons.org/licenses/by-nc/3.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (http://www.uk.sagepub.com/aboutus/openaccess.htm).This article has been made available through the Brunel Open Access Publishing Fund.Forest clearance is one of the main drivers of soil erosion and hydrological changes in mires, although climate may also play a significant role. Because of the wide range of factors involved, understanding these complex links requires long-term multi-proxy approaches and research on the best proxies to focus. A peat core from NW Spain (Cruz do Bocelo mire), spanning the last ~3000 years, has been studied at high resolution by physical (density and loss on ignition (LOI)), geochemical (elemental composition) and palynological (pollen and non-pollen palynomorphs) analyses. Proxies related to mineral matter fluxes from the catchment (lithogenic tracers, Glomus and Entorrhiza), rainfall (Bromine), mire hydrology (HdV-18), human pressure (Cerealia-type, nitrophilous taxa and coprophilous fungi) and forest cover (mesophilous tree taxa) were the most useful to reconstruct the evolution of the mire and its catchment. Forest clearance for farming was one of the main drivers of environmental change from at least the local Iron Age (~2685 cal. yr BP) onwards. The most intense phase of deforestation occurred during Roman and Germanic times and the late Middle Ages. During these phases, the entire catchment was affected, resulting in enhanced soil erosion and severe hydrological modifications of the mire. Climate, especially rainfall, may have also accelerated these processes during wetter periods. However, it is noteworthy that the hydrology of the mire seems to have been insensitive to rainfall variations when mesophilous forest dominated. Abrupt changes were only detected once intense forest clearance commenced during the Iron Age/Roman transition (~2190 cal. yr BP) phase, which represented a tipping point in catchment's ability to buffer impacts. Overall, our findings highlight the importance of studying ecosystems' long-term trajectories and catchment-wide processes when implementing mire habitat protection measures.This work was funded by the projects CGL2010-20672 (Plan Nacional I+D+i, Spanish Ministry of Science and Innovation) and 10PXIB200182PR (General Directorate of I+D, Xunta de Galicia). N Silva-Sánchez and L López-Merino are currently supported by a FPU predoctoral scholarship (AP2010-3264) funded by the Spanish Government and a MINT postdoctoral fellowship funded by the Brunel Institute for the Environment, respectively

    Benefícios dos Ativadores Seletivos dos Recetores de Vitamina D em Doentes Transplantados Renais

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    Severe chronic kidney disease may lead to disturbances, such as hyperphosphatemia, increased secretion of fibroblast growth factor -23 (FGF -23) and vitamin D deficiency. These may increase plasmatic levels of parathyroid hormone, and decrease plasmatic levels of calcium. Altogether, these may contribute to the development of secondary hyperparathyroidism, and to abnormalities in mineral metabolism. Kidney transplantation is the best option to improve longevity and quality of life in end -stage chronic kidney disease patients. Vitamin D deficiency has been associated with cardiovascular disease, which is the leading cause of death in chronic kidney disease. Therefore, diagnosing this deficiency may be pivotal for minimizing mortality in chronic kidney disease, because pharmacological treatments for this deficiency may be prescribed. Calcitriol is indicated for the treatment of vitamin D deficiency, both in chronic kidney disease and in kidney transplanted patients. However, calcitriol may increase the plasmatic levels of calcium and phosphorous, which can lead to vascular calcifications, that have been associated with cardiovascular mortality. Selective vitamin D receptor activators are indicated for the treatment of vitamin D deficiency in chronic kidney disease. These have the advantage of being associated with lower increases of plasmatic levels of calcium and phosphorous. These drugs also seem to have additional effects that may minimise patient morbidity and mortality, especially due to potentially reducing cardiovascular events. Unfortunately, there are few studies about the use of these drugs in kidney transplanted patients. Here we present a review about the physiology of vitamin D, the consequences of its deficiency in chronic kidney disease and in kidney transplanted patients, and about the diagnosis and treatment of this deficiency. Finally, we discuss the new line of research about the efficacy and safety of selective vitamin D receptor activators in kidney transplanted patients

    A methodological proposal for the complementarity of the SSM and the VSM for the analysis of viability in organizations

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    This paper presents a protocol that establishes the complementarity between Soft Systems Methodology (SSM) and the Viable System Model (VSM) for the analysis of viability in organizations. Various studies demonstrate the advantages of both hard and soft multimethodologies, especially in the field of operational research (OR). Relying on a literature review of multimethodology, the present research specifically focuses on papers that examine the resolution of problem situations in organizations using SSM and VSM. It subsequently addresses approaches to both methodologies and, as a result, presents the characteristics that favor complementarity. Thus, this research primarily contributes with a methodological proposal that integrates both SSM and VSM. In terms of its technical-methodological approach, this study proposes a comprehensive protocol for the integration of SSM and VSM. While some studies do extol the benefits of combining the two methodologies, a systematic protocol for their integration is still lacking. As such, the protocol presented herein consists of six steps used to diagnose or design a viable organization that includes a questionnaire for detecting organizational pathologies

    Numerical Modeling of the Internal Temperature in the Mammary Gland

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    The microwave thermometry method for the diagnosis of breast cancer is based on an analysis of the internal temperature distribution.This paper is devoted to the construction of a mathematical model for increasing the accuracy of measuring the internal temperature of mammary glands, which are regarded as a complex combination of several components, such as fat tissue, muscle tissue, milk lobules, skin, blood flows, tumor tissue. Each of these biocomponents is determined by its own set of physical parameters. Our numerical model is designed to calculate the spatial distributions of the electric microwave field and the temperature inside the biological tissue. We compare the numerical simulations results to the real medical measurements of the internal temperature.Comment: 8 pages, 4 figure

    Categorical Dimensions of Human Odor Descriptor Space Revealed by Non-Negative Matrix Factorization

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    In contrast to most other sensory modalities, the basic perceptual dimensions of olfaction remain unclear. Here, we use non-negative matrix factorization (NMF) – a dimensionality reduction technique – to uncover structure in a panel of odor profiles, with each odor defined as a point in multi-dimensional descriptor space. The properties of NMF are favorable for the analysis of such lexical and perceptual data, and lead to a high-dimensional account of odor space. We further provide evidence that odor dimensions apply categorically. That is, odor space is not occupied homogenously, but rather in a discrete and intrinsically clustered manner. We discuss the potential implications of these results for the neural coding of odors, as well as for developing classifiers on larger datasets that may be useful for predicting perceptual qualities from chemical structures

    The nutraceutical antihypertensive action of C-phycocyanin in chronic kidney disease is related to the prevention of endothelial dysfunction

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    C-phycocyanin (CPC) is an antihypertensive that is not still wholly pharmacologically described. The aim of this study was to evaluate whether CPC counteracts endothelial dysfunction as an antihypertensive mechanism in rats with 5/6 nephrectomy (NFx) as a chronic kidney disease (CKD) model. Twenty-four male Wistar rats were divided into four groups: sham control, sham-treated with CPC (100 mg/Kg/d), NFx, and NFx treated with CPC. Blood pressure was measured each week, and renal function evaluated at the end of the treatment. Afterward, animals were euthanized, and their thoracic aortas were analyzed for endothelium functional test, oxidative stress, and NO production. 5/6 Nephrectomy caused hypertension increasing lipid peroxidation and ROS production, overexpression of inducible nitric oxide synthase (iNOS), reduction in the first-line antioxidant enzymes activities, and reduced-glutathione (GSH) with a down-expression of eNOS. The vasomotor response reduced endothelium-dependent vasodilation in aorta segments exposed to acetylcholine and sodium nitroprusside. However, the treatment with CPC prevented hypertension by reducing oxidative stress, NO system disturbance, and endothelial dysfunction. The CPC treatment did not prevent CKD-caused disturbance in the antioxidant enzymes activities. Therefore, CPC exhibited an antihypertensive activity while avoiding endothelial dysfunction

    Antimicrobial and antioxidant screening of curcumin and pyrocatechol in the prevention of biodiesel degradation: oxidative stability

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    Owing to its hygroscopicity biodiesel may accumulate water during storage, which becomes favorable to the growth of microorganisms. In order to control microbial contamination, use of various chemical biocides has been studied. However, the addition of a natural substance simultaneously with antioxidant and microbial growth inhibition could prove advantageous in the prevention of biodiesel oxidation and microbial contamination. Curcumin and pyrocatechol are antioxidant agents, which also exhibit microbial growth inhibition abilities. This research effort aimed at evaluating the addition of curcumin and pyrocatechol to biodiesel produced from various vegetable sources (waste frying oil, soybean oil, cottonseed oil, sesame oil, macaúba almond oil and microalgae oil). The combined addition of 1% (w/w) water and curcumin (viz. 0.2% (w/w) for biodiesel from spent frying oil, 0.5% (w/w) for biodiesel from soybean oil, 0.1% (w/w) for biodiesel from cotton seed oil, 0.5% (w/w) for biodiesel from sesame seed oil, 0.2% (w/w) for biodiesel from macaúba almond oil, and 0.2% (w/w) for biodiesel from microalgae oil) were those processing variables that promoted the best fungistatic and antioxidant effects, allowing maintenance of an unfavorable environment for microbial growth in biodiesel inoculated with the ubiquitous filamentous mold Paecilomyces variotii Bainier.Project funding by CNPq (National Council for Scientific and Technological Development - Brazil) (CNPq Ref. No. 404808/ 2013-1, Project ‘Studies on Biodiesel: Development of analytical methods for the characterization and quality control, and research of new natural additives to improve the quality of this biofuel’), is hereby gratefully acknowledged. This work received support from CNPq, National Council for Scientific and Technological Development Brazil, in the form of Research Productivity (PQ) fellowships granted to Victor M. Balcão (Ref. No. 306113/2014-7) and Marco V. Chaud (Ref. No. 309598/2014-1). The authors have no conflicts of interest whatsoever to declare

    The role of family in the intergenerational transmission of collective action

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordThe present research demonstrates intergenerational influences on collective action participation, whereby parents’ past and current participation in collective action (descriptive family norms) shape their children’s participation in conventional and radical collective action via injunctive family norms (perception that parents value such participation). Two unique data sets were used: dyads of activist parents and their adult children (Study 1, N = 100 dyads) and student activists who participated in a yearlong, three-wave longitudinal study (Study 2, Ns wave 1 = 1,221, Wave 2 = 960, and Wave 3 = 917). Parents’ past and current participation directly and indirectly predicted children’s protest participation in Study 1, while Study 2 showed a similar pattern longitudinally: Perceptions of parents’ participation (descriptive family norm) and approval (injunctive family norm) predicted change in collective action participation over time. Together, results highlight family environment as a critical setting for the intergenerational transmission of protest
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