2,669 research outputs found

    Note on the Markus–Yamabe conjecture for gradient dynamical systems

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    AbstractLet v:Rn→Rn be a C1 vector field which has a singular point O and its linearization is asymptotically stable at every point of Rn. We say that the vector field v satisfies the Markus–Yamabe conjecture if the critical point O is a global attractor of the dynamical system x˙=v(x). In this note we prove that if v is a gradient vector field, i.e. v=∇f (f∈C2), then the basin of attraction of the critical point O is the whole Rn, thus implying the Markus–Yamabe conjecture for this class of vector fields. An analogous result for discrete dynamical systems of the form xm+1=∇f(xm) is proved

    A characterization of 3D steady Euler flows using commuting zero-flux homologies

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    We characterize, using commuting zero-flux homologies, those volume-preserving vector fields on a 33-manifold that are steady solutions of the Euler equations for some Riemannian metric. This result extends Sullivan's homological characterization of geodesible flows in the volume-preserving case. As an application, we show that the steady Euler flows cannot be constructed using plugs (as in Wilson's or Kuperberg's constructions). Analogous results in higher dimensions are also proved

    Getting Better Intestinal Health through the Addition of Yeast (Saccharomyces Cerevisiae) Combined with Threonine in Broilers Diets

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    The aim was to evaluate the association of Saccharomyces cerevisiae (Sc) with Threonine (T) in broiler diets, on performance, carcass quality and gut histomorphometric variables. One hundred Ross male broilers (1 to 43 days old) were distributed into four treatments. D1: commercial type, plus 5 g Sc/Kg food, D2: D1 plus 15% T, D3: D1 plus 30% T, D4: D1 plus 45% T. Performance productive were measured as Average Daily Weight Gain (ADWG) (g/broiler/day), Average Daily Consumption Feed (ADCF) (g/broiler/day) and Feed Conversion Ratio (FCR). Carcass quality was determined as Breast Weight (BW) (g), Thigh Weight (TW) (g) and Abdominal Fat Weight (AFW) (g). In gut were measured: Villus Height (VH) (”), Crypt Depth (CD) (”) and VH/CD Ratio. Results: BW and TW increased and AFW decreased in D3 and D4 groups (p ? 0.05). In gut, all groups received T decreased VH/CD Ratio (p ? 0.05) and increased goblet cells number producing higher mucus. Conclusion: Sc associate with T increased carcass quality of broiler through a healthy gut, that could be generated by more mature epithelia that enhancing absorptive function through the efficient use of nutrient and increasing protective function through mucosal hypersecretion by increased goblet cell number

    Average stresses and force fluctuations in non-cohesive granular materials

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    A lattice model is presented for investigating the fluctuations in static granular materials under gravitationally induced stress. The model is similar in spirit to the scalar q-model of Coppersmith et al., but ensures balance of all components of forces and torques at each site. The geometric randomness in real granular materials is modeled by choosing random variables at each site, consistent with the assumption of cohesionless grains. Configurations of the model can be generated rapidly, allowing the statistical study of relatively large systems. For a 2D system with rough walls, the model generates configurations consistent with continuum theories for the average stresses (unlike the q-model) without requiring the assumption of a constitutive relation. For a 2D system with periodic boundary conditions, the model generates single-grain force distributions similar to those obtained from the q-model with a singular distribution of q's.Comment: 18 pages, 10 figures. Uses aps,epsfig,graphicx,floats,revte

    X-ray emission from a liquid curtain jet when irradiated by femtosecond laser pulses

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    Laser-based sources of ionizing radiation have attracted considerable attention in the last years for their broad potential applications. However, the stability and robustness of such sources are still issues that need to be addressed. Aiming to solve such problems, we propose a source that uses a liquid jet—rather than a solid—as a target for the production of X-rays. Liquid jets offer always a clean surface for every laser shot which represent a clear advantage over solids. In this work, we present an experimental characterization of the X-ray emission of such targets, and study the efficiency of the process when two temporally delayed pulses are used. According to the obtained results, the X-ray yield is comparable with commonly used targets.Ministerio de Economía y Competitividad FIS2016- 81056-

    Treatment of type 2 diabetes by patient profile in the clinical practice of endocrinology in Spain: Delphi study results from the think twice program

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    Introduction: The aim of this Delphi study is to unveil the management of patients with type 2 diabetes (T2D) and different levels of complexity in the clinical practice in Spain. Methods: Based on the common management practices of T2D profiles reported by Spanish endocrinologists, a Delphi questionnaire of 55 statements was developed and responded to by a national panel (n = 101). Results: A consensus was reached for 30 of the 55 statements. Regarding overweight patients inadequately controlled with metformin, treatment with a sodium-glucose transport protein 2 inhibitor (SGLT2-I) is preferred over treatment with a dipeptidyl peptidase-4 inhibitor (DPP4-I). If the patient is already being treated with a DPP4-I, an SGLT2-I is added on to the treatment regimen rather than replacing the DPP4-I. Conversely, if the treatment regimen includes a sulfonylurea, it is usually replaced by other antihyperglycemic agents. Current treatment trends in uncontrolled obese patients include the addition of an SGLT2-I or a glucagon-like peptide-1 receptor agonist (GLP1-RA) to background therapy. When the glycated hemoglobin target is not reached, triple therapy with metformin ? GLP1-RA ? SGLT2-I is initiated. Although SGLT2-Is are the treatment of choice in patients with T2D and heart failure or uncontrolled hypertension, no consensus was reached regarding the preferential use of SGLT2- Is or GLP1-RAs in patients with established cardiovascular disease. Conclusion: Consensus has been reached for a variety of statements regarding the management of several T2D profiles. Achieving a more homogeneous management of complex patients with T2D may require further evidence and a better understanding of the key drivers for treatment choice

    Colombian essential oil of ruta graveolens against nosocomial antifungal resistant candida strains

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    Drug resistance in antifungal therapy, a problem unknown until a few years ago, is increasingly assuming importance especially in immunosuppressed patients and patients receiving chemotherapy and radiotherapy. In the past years, the use of essential oils as an approach to improve the effectiveness of antifungal agents and to reduce antifungal resistance levels has been proposed. Our research aimed to evaluate the antifungal activity of Colombian rue, Ruta graveolens, essential oil (REO) against clinical strains of Candida albicans, Candida parapsilopsis, Candida glabrata, and Candida tropicalis. Data obtained showed that C. tropicalis and C. albicans were the most sensitive strains showing minimum inhibitory concentrations (MIC) of 4.1 and 8.2 ”g/mL of REO. Time–kill kinetics assay demonstrated that REO showed a fungicidal effect against C. tropicalis and a fungistatic effect against C. albicans. In addition, an amount of 40% of the biofilm formed by C. albicans was eradicated using 8.2 ”g/mL of REO after 1 h of exposure. The synergistic effect of REO together with some antifungal compounds was also investigated. Fractional inhibitory concentration index (FICI) showed synergic effects of REO combined with amphotericin B. REO Lead a disruption in the cellular membrane integrity, consequently resulting in increased intracellular leakage of the macromolecules, thus confirming that the plasma membrane is a target of the mode of action of REO against C. albicans and C. tropicalis

    Salt marsh fragmentation in a mesotidal estuary:Implications for medium to long-term management

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    During the last decades many salt marshes worldwide have suffered important losses in their extent and associated ecosystem services. The salt marshes of San Vicente de la Barquera estuary (N Spain) are a clear example of this, with a drastic reduction in vegetation surface over the last 60 years. This paper provides insights into the main factors controlling salt marsh functioning in sheltered estuarine areas. Regional and local factors have been disaggregated to identify the main drivers controlling the functioning of the salt marsh to develop appropriate management measures according to the evolution of the system. These factors have been studied in their spatial context through detailed maps of change in vegetation cover combined with topographic data obtained from UAV and RTK-DGPS surveys. The results demonstrate that in this estuary the salt marsh area is declining following a fragmentation process. No clear pattern of vegetation loss/gain with elevation has been identified. However, the results point to increased hydrodynamic stress in the area, with stronger currents inside the estuary. This is probably the major factor responsible for the decline of the salt marshes in the San Vicente de la Barquera estuary. Furthermore, several human interventions during the 20th century (local drivers) have also probably contributed to a lower resilience against SLR (regional driver). This work demonstrates that both natural and human drivers of change need to be considered when characterizing the evolution of salt marshes, wherever efficient management strategies need to be designed

    Salt marsh fragmentation in a mesotidal estuary:Implications for medium to long-term management

    Get PDF
    During the last decades many salt marshes worldwide have suffered important losses in their extent and associated ecosystem services. The salt marshes of San Vicente de la Barquera estuary (N Spain) are a clear example of this, with a drastic reduction in vegetation surface over the last 60 years. This paper provides insights into the main factors controlling salt marsh functioning in sheltered estuarine areas. Regional and local factors have been disaggregated to identify the main drivers controlling the functioning of the salt marsh to develop appropriate management measures according to the evolution of the system. These factors have been studied in their spatial context through detailed maps of change in vegetation cover combined with topographic data obtained from UAV and RTK-DGPS surveys. The results demonstrate that in this estuary the salt marsh area is declining following a fragmentation process. No clear pattern of vegetation loss/gain with elevation has been identified. However, the results point to increased hydrodynamic stress in the area, with stronger currents inside the estuary. This is probably the major factor responsible for the decline of the salt marshes in the San Vicente de la Barquera estuary. Furthermore, several human interventions during the 20th century (local drivers) have also probably contributed to a lower resilience against SLR (regional driver). This work demonstrates that both natural and human drivers of change need to be considered when characterizing the evolution of salt marshes, wherever efficient management strategies need to be designed.</p

    Assessing the Policy Landscape for Salt Reduction in South-East Asian and Latin American Countries – An Initiative Towards Developing an Easily Accessible, Integrated, Searchable Online Repository

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    BACKGROUND: High dietary salt intake is an avoidable cause of hypertension and associated cardiovascular diseases (CVDs). Thus, salt reduction is recommended as one of the most cost-effective interventions for CVD prevention and for achieving the World Health Organization’s (WHO) 25% reduction in premature non-communicable disease (NCD) mortality by 2025. However, current and comprehensive information about national salt reduction policies and related actions across different regions are difficult to access and impede progress and monitoring. OBJECTIVES: As an initial step to developing an online repository of salt reduction policies and related actions, and to track nation-wise progress towards the WHO’s 25 by 25 goal, we aimed to identify and assess salt reduction policies and actions in select countries from two of the top five most populous regions of the world- the South-East Asia and Latin America. METHODS: We conducted a literature review to identify national and regional salt reduction policies in the selected South-East Asian and Latin American countries, from January 1990–August 2020, available in English and Spanish. We also contacted selected WHO country offices (South-East Asian region) or relevant national authorities (Latin America) to gain access to unpublished documents. RESULTS: In both regions, we found only a few dedicated stand-alone salt reduction policies: Bhutan, Sri-Lanka and Thailand from South East Asia and Costa Rica from Latin America. Available polices were either embedded in other national health/nutritional policy documents/overall NCD policies or were unpublished and had to be accessed via personal communication. CONCLUSIONS: Salt reduction policies are limited and often embedded with other policies which may impede their implementation and utility for tracking national and international progress towards the global salt reduction target associated with the 25 by 25 goal. Developing an online repository could help countries address this gap and assist researchers/policymakers to monitor national progress towards achieving the salt reduction target
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