1,887 research outputs found

    Natriuretic peptides and NGAL in heart failure: does a link exist?

    Get PDF
    In recent years there has been growing interest in the development of new diagnostic tools and particularly in laboratory tests for the identification of heart failure (HF) patients. Because of the rise in HF occurrence, it is necessary to use simple and reliable method to recognize those patients at risk before the onset of the clinical symptoms. To date HF diagnosis remains difficult: its symptoms and signs are often non specific as well as being poor sensitive indicators for HF severity. Throughout the last 10 years published literature has highlighted a boom in the use of biomarkers for HF. Both B-type and N-terminal pro-B-type natriuretic peptides have demonstrated specific role in heart failure diagnosis, as well as risk assessment. A single determination of BNP at any time during the development of chronic heart failure (CHF) provides a clinically useful tool to establish the outcome. Renal dysfunction is often associated with heart failure and predicts adverse clinical outcomes. Many studies have recently suggested the clinical use of serum neutrophil gelatinase-associated lipocalin (NGAL) levels in patients admitted to the hospital for acute HF can be used to estimate the risk of early worsening renal function. This could be potentially applied in clinical practice for early identification of renal dysfunction development in patients with HF. NGAL levels appear also to predict renal dysfunction in patients with chronic HF and preserved renal function. For all these reasons, BNP and NGAL are two emerging tools useful for diagnosis and prognosis in HF. The combination of two laboratory biomarkers could potentially identify patients with more elevated risks of both cardiac hemodynamic impairment and kidney dysfunction

    Impacts of the Last Glacial Cycle on ground surface temperature reconstructions over the last millennium

    Get PDF
    Borehole temperature profiles provide robust estimates of past ground surface temperature changes, in agreement with meteorological data. Nevertheless, past climatic changes such as the Last Glacial Cycle (LGC) generated thermal effects in the subsurface that affect estimates of recent climatic change from geothermal data. We use an ensemble of ice sheet simulations spanning the last 120 ka to assess the impact of the Laurentide Ice Sheet on recent ground surface temperature histories reconstructed from borehole temperature profiles over North America. When the thermal remnants of the LGC are removed, we find larger amounts of subsurface heat storage (2.8 times) and an increased warming of the ground surface over North America by 0.75 K, both relative to uncorrected borehole estimates

    Industry 4.0 and sustainability: Towards conceptualization and theory

    Get PDF
    Both Industry 4.0 and sustainability have gained momentum in the academic, managerial and policy debate. Despite the relevance of the topics, the relation between Industry 4.0 and sustainability \u2013 revealed by many authors \u2013 is still unclear; literature is fragmented. This paper seeks to overcome this limit by developing a systematic literature review of 117 peer-reviewed journal articles. After descriptive and content analyses, the work presents a conceptualization and theoretical framework. The paper contributes to both theory and practice by advancing current understanding of Industry 4.0 and sustainability, especially the impact of Industry 4.0 technologies on sustainability practices and performance

    Characterizing land surface processes: A quantitative analysis using air-ground thermal orbits

    Get PDF
    A quantitative analysis of thermal orbits is developed and applied to modeled air and ground temperatures. Thermal orbits are phase-space representations of air and ground temperature relationships that are generated by plotting daily or monthly ground temperatures against air temperatures. Thermal orbits are useful descriptive tools that provide straightforward illustrations of air and ground temperature relationships in the presence of land surface processes related to snow cover, soil freezing, and vegetation effects. The utility of thermal orbits has been limited, however, by the lack of quantitative analyses that describe changes in orbits across different environments or in time. This shortcoming is overcome in the present study by developing a linear regression analysis of thermal orbits that allows changes to be tracked in time and space and as a function of depth within the subsurface. The theory that underlies the thermal orbit regression analysis is developed herein, and the utility of the application is demonstrated using controlled model experiments

    Borehole climatology: a discussion based on contributions from climate modeling

    Get PDF
    Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries. The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change. The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments

    The role of natriuretic peptides for the diagnosis of left ventricular dysfunction

    Get PDF
    Natriuretic peptides (NPs) are entered in current guidelines for heart failure (HF) diagnosis and management because of their high specificity and sensibility in screening patients with acute dyspnea. Due to their availability and relatively low cost, they became the first step examinations in HF patients evaluation at hospital admission together with clinical and chest radiography examination. NPs are released following any cardiac haemodynamic stress due to volume or pressure overload and should be considered as a mirror of cardiac condition helping in recognizing patients with poor outcome. Moreover, the exact role of NPs in early HF stages, in isolated diastolic dysfunction, and in general population is questioned. Several promising reports described their potential role; however, the wide cut-off definition, inclusion criteria, and intrinsic measurement biases do not actually consent to their clinical application in these settings. A multimodality strategy including both NPs and imaging studies appears to be the best strategy to define the cardiac dysfunction etiology and its severity as well as to identify patients with higher risk. In this review, we describe the current and potential role of NPs in patients with asymptomatic cardiac insufficiency, evaluating the requirement to obtain a better standardization for imaging as for laboratory criteria

    Small Scale Equipment for Date Processing

    Get PDF

    Perturbation Theory for Metastable States of the Dirac Equation with Quadratic Vector Interaction

    Full text link
    The spectral problem of the Dirac equation in an external quadratic vector potential is considered using the methods of the perturbation theory. The problem is singular and the perturbation series is asymptotic, so that the methods for dealing with divergent series must be used. Among these, the Distributional Borel Sum appears to be the most well suited tool to give answers and to describe the spectral properties of the system. A detailed investigation is made in one and in three space dimensions with a central potential. We present numerical results for the Dirac equation in one space dimension: these are obtained by determining the perturbation expansion and using the Pad\'e approximants for calculating the distributional Borel transform. A complete agreement is found with previous non-perturbative results obtained by the numerical solution of the singular boundary value problem and the determination of the density of the states from the continuous spectrum.Comment: 10 pages, 1 figur
    • …
    corecore