661 research outputs found

    Chern correspondence for higher principal bundles

    Full text link
    The classical Chern correspondence states that a choice of Hermitian metric on a holomorphic vector bundle determines uniquely a unitary 'Chern connection'. This basic principle in Hermitian geometry, later generalized to the theory of holomorphic principal bundles, provides one of the most fundamental ingredients in modern gauge theory, via its applications to the Donaldson-Uhlenbeck-Yau Theorem. In this work we study a generalization of the Chern correspondence in the context of higher gauge theory, where the structure group of the bundle is categorified. For this, we define connective structures on a multiplicative gerbe and propose a natural notion of complexification for an important class of 2-groups. Using this, we put forward a new notion of higher connection which is well-suited for describing holomorphic principal 2-bundles for these 2-groups, and establish a Chern correspondence in this way. As an upshot of our construction, we unify two previous notions of higher connections in the literature, namely those of adjusted connections and of trivializations of Chern-Simons 2-gerbes with connection.Comment: 48 page

    Effectiveness of Mechanical Horse-Riding Simulators on Postural Balance in Neurological Rehabilitation: Systematic Review and Meta-Analysis

    Get PDF
    Mechanical horse-riding simulators consist of a device that mimics the movement of a real horse, generating between 50 and 100 three-dimensional physical movements (forward and back, left and right, up and down). The main objective of this study is to analyze the effectiveness of mechanical horse-riding simulators to improve postural balance in subjects with neurological disorders. The search was conducted during January-March 2019 in PubMed, Physiotherapy Evidence Database (PEDro), Cochrane, Web of Science, CINAHL, and Scopus. The methodological quality of the studies was evaluated through the PEDro scale. A total of seven articles were included in this systematic review, of which four contributed information to the meta-analysis. Statistical analysis showed favorable results for balance in stroke patients, measured by the Berg Balance Scale (standardized mean difference (SMD) = 3.24; 95%; confidence interval (CI): 1.66-4.83). Not conclusive results were found in sitting postural balance, measured using the Gross Motor Function Measure-66 (GMFM-66) Sitting Dimension, in patients with cerebral palsy. Most studies have shown beneficial effects on postural balance compared with conventional physical therapy. However, due to the limited number of articles and their low methodological quality, no solid conclusions can be drawn about the effectiveness of this therapy

    Stenocarpella maydis and Sporisorium reilianum: Two Pathogenic Fungi of Maize

    Get PDF
    Stenocarpella maydis and Sporisorium reilianum are phytopathogenic fungi that cause white rot in corn cob and head smut in maize (Zea mays L.) respectively, diseases that are spread worldwide and cause many economic losses. In this chapter the characteristics of the above diseases, such as their life cycle, pathogenicity factors, control methods, as well as the biotechnological potential of the fungi involved in this processes are described, specifically in connection to their extracellular enzymes

    1D and 3D supramolecular structures exhibiting weak ferromagnetism in three Cu(II) complexes based on malonato and di-alkyl-2,2’-bipyridines

    Get PDF
    Abstract Manganese coordination polymers {Mn(- fum)(5dmb)(H2O)2}n (1) and {[Mn2(fum)2(4dmb)2] H2O}n (2) (fum= fumarato; 5dmb = 5,50-dimethyl-2,20-bipyridine; 4dmb = 4,40-dimethyl-2,20-bipyridine) were obtained from one-pot, solution reactions under ambient conditions. The fum ligand acquires different coordination modes in the presence of the different dmb ancillary ligands, promoting distinctive crystal structures, including divergent dimensionalities. Thus, X-ray single-crystal data reveal that complex 1 crystallizes in a monoclinic system with C2/c space group and forms an infinite one-dimensional polymer. The Mn(II) center is six-coordinated and displays a distorted octahedral configuration. In addition, the solid-state selfassembly of the polymeric structure of 1 gives rise to a twodimensional (2D) supramolecular framework, mainly through hydrogen bonding. In contrast, complex 2 crystallizes in a monoclinic system with a Cc space group and forms an infinite 2D coordination polymer having dinuclear units. The Mn(II) center has a distorted octahedral configuration. The thermal stabilities of both coordination polymers were investigated. Variable-temperature magnetic measurements show that complex 1 is paramagnetic, while complex 2 exhibits weak antiferromagnetic coupling between adjacent Mn(II) centers.supported by CONACyT project 129293, DGAPA-UNAM project IN106014, and ICYTDF, project PICCO

    Study of the influence of Xanthate Derivative Structures on Copper Sulfide Mineral Adsorption Under Acidic Conditions

    Get PDF
    Artículo de investigación en revista indizadaAdsorption of commercial xanthate derivatives on copper sulfide mineral (covellite, CuS) was studied by kinetics and isotherm adsorption experiments. The adsorption of xanthate derivatives was confirmed by FTIR (Fourier transform infrared spectroscopy) and XPS (X-ray photoelectron spectroscopy) results. Experiments were performed with two different xanthate derivatives, C-4410 (O-pentyl S-2-propenyl ester) and C-4940 (isobutyl xanthogen ethyl formate), on individual doses of 0.05 g of powdered covellite. It was found that the equilibrium times at pH 2, 4, and 6 were different for both xanthate derivatives. The shortest times were achieved at pH 2 and 4. The results suggest that C-4110 can be used as collector in a wide range of pH, while C-4940 is limited to lower pH values. Pseudo first- and pseudo second-order kinetics models were thus applied to the experimental data for pH 2. The information obtained from the kinetics models combined with XPS allowed proposing the adsorption mechanism for the covellite-xanthate derivative pair. The adsorption takes place through a non-covalent interaction for C-4410 and chemisorption process for C-4940. The best-fitting isotherm models for C-4410 and C-4940 adsorption were Redlich–Peterson and Freundlich, respectively, which yield a maximum adsorption capacity of 57.07 mg g 1 for C-4410 and 44.62 mg g 1 for C-4940.CONACYT CB-254952-201

    Cohort profile: the Hortega Study for the evaluation of non-traditional risk factors of cardiometabolic and other chronic diseases in a general population from Spain.

    Get PDF
    PURPOSE: The Hortega Study is a prospective study, which investigates novel determinants of selected chronic conditions with an emphasis on cardiovascular health in a representative sample of a general population from Spain. PARTICIPANTS: In 1997, a mailed survey was sent to a random selection of public health system beneficiaries assigned to the University Hospital Rio Hortega's catchment area in Valladolid (Spain) (n=11 423, phase I), followed by a pilot examination in 1999-2000 of 495 phase I participants (phase II). In 2001-2003, the examination of 1502 individuals constituted the Hortega Study baseline examination visit (phase III, mean age 48.7 years, 49% men, 17% with obesity, 27% current smokers). Follow-up of phase III participants (also termed Hortega Follow-up Study) was obtained as of 30 November 2015 through review of health records (9.5% of participants without follow-up information). FINDINGS TO DATE: The Hortega Study integrates baseline information of traditional and non-traditional factors (metabolomic including lipidomic and oxidative stress metabolites, genetic variants and environmental factors, such as metals), with 14 years of follow-up for the assessment of mortality and incidence of chronic diseases. Preliminary analysis of time to event data shows that well-known cardiovascular risk factors are associated with cardiovascular incidence rates, which add robustness to our cohort. FUTURE PLANS: In 2020, we will review updated health and mortality records of this ongoing cohort for a 5-year follow-up extension. We will also re-examine elder survivors to evaluate specific aspects of ageing and conduct geolocation to study additional environmental exposures. Stored biological specimens are available for analysis of new biomarkers. The Hortega Study will, thus, enable the identification of novel factors based on time to event data, potentially contributing to the prevention and control of chronic diseases in ageing populations

    LDL particle size and composition and incident cardiovascular disease in a South-European population: The Hortega-Liposcale Follow-up Study.

    Get PDF
    The association of low-density lipoprotein (LDL) particle composition with cardiovascular risk has not been explored before. The aim was to evaluate the relationship between baseline LDL particle size and composition (proportions of large, medium and small LDL particles over their sum expressed as small-LDL %, medium-LDL % and large-LDL %) and incident cardiovascular disease in a population-based study. Methods: Direct measurement of LDL particles was performed using a two-dimensional NMR-technique (Liposcale®). LDL cholesterol was assessed using both standard photometrical methods and the Liposcale® technique in a representative sample of 1162 adult men and women from Spain. Results: The geometric mean of total LDL particle concentration in the study sample was 827.2 mg/dL (95% CI 814.7, 839.8). During a mean follow-up of 12.4 ± 3.3 years, a total of 159 events occurred. Medium LDL particles were positively associated with all cardiovascular disease, coronary heart disease (CHD) and stroke after adjustment for traditional risk factors and treatment. Regarding LDL particle composition, the multivariable adjusted hazard ratios for CHD for a 5% increase in medium and small LDL % by a corresponding decrease of large LDL % were 1.93 (1.55, 2.39) and 1.41 (1.14, 1.74), respectively. Conclusions: Medium LDL particles were associated with incident cardiovascular disease. LDL particles showed the strongest association with cardiovascular events when the particle composition, rather than the total concentration, was investigated. A change in baseline composition of LDL particles from large to medium and small LDL particles was associated with an increased cardiovascular risk, especially for CHD

    Mortality and cardiovascular disease burden of uncontrolled diabetes in a registry-based cohort: the ESCARVAL-risk study

    Get PDF
    BACKGROUND: Despite the epidemiological evidence about the relationship between diabetes, mortality and cardiovascular disease, information about the population impact of uncontrolled diabetes is scarce. We aimed to estimate the attributable risk associated with HbA1c levels for all-cause mortality and cardiovascular hospitalization. METHODS: Prospective study of subjects with diabetes mellitus using electronic health records from the universal public health system in the Valencian Community, Spain 2008-2012. We included 19,140 men and women aged 30 years or older with diabetes who underwent routine health examinations in primary care. RESULTS: A total of 11,003 (57%) patients had uncontrolled diabetes defined as HbA1c ≥6.5%, and, among those, 5325 participants had HbA1c ≥7.5%. During an average follow-up time of 3.3 years, 499 deaths, 912 hospitalizations for coronary heart disease (CHD) and 786 hospitalizations for stroke were recorded. We observed a linear and increasingly positive dose-response of HbA1c levels and CHD hospitalization. The relative risk for all-cause mortality and CHD and stroke hospitalization comparing patients with and without uncontrolled diabetes was 1.29 (95 CI 1.08,1.55), 1.38 (95 CI 1.20,1.59) and 1.05 (95 CI 0.91, 1.21), respectively. The population attributable risk (PAR) associated with uncontrolled diabetes was 13.6% (95% CI; 4.0-23.9) for all-cause mortality, 17.9% (95% CI; 10.5-25.2) for CHD and 2.7% (95% CI; - 5.5-10.8) for stroke hospitalization. CONCLUSIONS: In a large general-practice cohort of patients with diabetes, uncontrolled glucose levels were associated with a substantial mortality and cardiovascular disease burden

    Nitrate and nitrite in drinking water affect antioxidant enzymes in erythrocytes of rats

    Get PDF
    The present study evaluated the effect of short term intake of nitrite and nitrate drinking water on the antioxidant system and membrane damage of rat erythrocytes. Wistar rats were randomly divided into three groups as follows; the group I received only distilled water ad libitum; the group II was given water with nitrate (a dose of 124 mg/kg of nitrate-nitrogen) as drinking water and the group III was given nitrites dissolved in distilled water in a dose of 150 mg/kg for 7 days. At the end of the study, group III rats showed a significant decrease in activities of glutathione peroxidase (GPx), glucose 6-phosphate dehydrogenase (G6PDH) and catalase (CAT), while in group II rats, the activity of GPx and CAT were significantly reduced, but no significant changes in glutathione reductase activity and peroxynitrite levels were observed. On the other hand, malondialdehyde (MDA) was increased in both groups with respect to group I. Also, our major results indicate that all treatments changed methemoglobin levels and osmotic fragility in comparison to group I rats. The intensity of alterations was found more severe in rats of group III, followed by rats of group II. It can be concluded from these observations that nitrate or nitrite leads to alterations in the erythrocytes antioxidant defense status mainly throughout NADPH relate enzymes
    corecore