26 research outputs found
When should we treat isolated high triglycerides?
No evidence exists that treating isolated high triglyceride levels in the absence of other risk factors prevents coronary events. Although elevated triglycerides in some studies correlates with coronary events, the association weakens when controlled for factors such as diabetes, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, body mass index, and other cardiac risk factors. Coincident lowering of triglycerides, while treating other dyslipidemias (such as high LDL and low HDL), can contribute to decreasing coronary events (strength of recommendation [SOR]: A, based randomized controlled trials). Treating triglyceride levels over 500 to 1000 mg/dL may reduce the risk of pancreatitis (SOR: C, expert opinion)
A Robust Consensus Algorithm for Current Sharing and Voltage Regulation in DC Microgrids
In this paper a novel distributed control algorithm for current sharing and
voltage regulation in Direct Current (DC) microgrids is proposed. The DC
microgrid is composed of several Distributed Generation units (DGUs), including
Buck converters and current loads. The considered model permits an arbitrary
network topology and is affected by unknown load demand and modelling
uncertainties. The proposed control strategy exploits a communication network
to achieve proportional current sharing using a consensus-like algorithm.
Voltage regulation is achieved by constraining the system to a suitable
manifold. Two robust control strategies of Sliding Mode (SM) type are developed
to reach the desired manifold in a finite time. The proposed control scheme is
formally analyzed, proving the achievement of proportional current sharing,
while guaranteeing that the weighted average voltage of the microgrid is
identical to the weighted average of the voltage references.Comment: 12 page
Robust Passivity-Based Control of Boost Converters in DC Microgrids
This work deals with the design of a robust and decentralized passivity-based
control scheme for regulating the voltage of a DC microgrid through boost
converters. A Krasovskii-type storage function is proposed and a (local)
passivity property for DC microgrids comprising unknown 'ZIP' (constant
impedance 'Z', constant current 'I' and constant power 'P') loads is
established. More precisely, the input port-variable of the corresponding
passive map is equal to the first-time derivative of the control input. Then,
the integrated input port-variable is used to shape the closed loop storage
function such that it has a minimum at the desired equilibrium point.
Convergence to the desired equilibrium is theoretically analyzed and the
proposed control scheme is validated through experiments on a real DC
microgrid
Platinum catalysed aerobic selective oxidation of cinnamaldehyde to cinnamic acid
Aerobic selective oxidation of allylic aldehydes offers an atom and energy efficient route to unsaturated carboxylic acids, however suitable heterogeneous catalysts offering high selectivity and productivity have to date proved elusive. Herein, we demonstrate the direct aerobic oxidation of cinnamaldehyde to cinnamic acid employing silica supported Pt nanoparticles under base-free, batch and continuous flow operation. Surface and bulk characterisation of four families of related Pt/silica catalysts by XRD, XPS, HRTEM, CO chemisorption and N_{2} porosimetry evidence surface PtO_{2} as the common active site for cinnamaldehyde oxidation, with a common turnover frequency of 49,000 ± 600 h^{-1}; competing cinnamaldehyde hydrogenolysis is favoured over metallic Pt. High area mesoporous (SBA-15 or KIT-6) and macroporous-mesoporous SBA-15 silicas confer significant rate and cinnamic acid yield enhancements versus low area fumed silica, due to superior platinum dispersion. High oxygen partial pressures and continuous flow operation stabilise PtO_{2} active sites against in-situ reduction and concomitant deactivation, further enhancing cinnamic acid productivity
Brain energy rescue:an emerging therapeutic concept for neurodegenerative disorders of ageing
The brain requires a continuous supply of energy in the form of ATP, most of which is produced from glucose by oxidative phosphorylation in mitochondria, complemented by aerobic glycolysis in the cytoplasm. When glucose levels are limited, ketone bodies generated in the liver and lactate derived from exercising skeletal muscle can also become important energy substrates for the brain. In neurodegenerative disorders of ageing, brain glucose metabolism deteriorates in a progressive, region-specific and disease-specific manner — a problem that is best characterized in Alzheimer disease, where it begins presymptomatically. This Review discusses the status and prospects of therapeutic strategies for countering neurodegenerative disorders of ageing by improving, preserving or rescuing brain energetics. The approaches described include restoring oxidative phosphorylation and glycolysis, increasing insulin sensitivity, correcting mitochondrial dysfunction, ketone-based interventions, acting via hormones that modulate cerebral energetics, RNA therapeutics and complementary multimodal lifestyle changes
Collaborative design in a context of sustainability: The epistemological an practical implications of the precautionary principle for design
Sustainable design is an approach that seeks to adopt an ethic of the future, where the vision of the solutions is based on a temporal and spatial perspective that is predominantly long-term and global. Design is characterized by its projective and ambivalent nature, and therefore a conscious effort to anticipate the outcomes of design intentions is crucial. Consequently, all design is inherently laden with uncertainty, doubt, and specifically in some technology-driven design projects - contradictions and controversies. Typically, such uncertainties and contradictions are not considered during the initial phase, since the main goal at this phase is to simplify the problem, and therefore these anomalies are often omitted, as they are seen to be outside the boundaries of the design problem. How can designers consider the uncertainties and contradictions during conceptualization, as well as consider the benefits resulting from their design proposals? Designers in their sustainable design practice must consider (1) the multiple objectives and criteria; (2) the multiple users and user preferences; (3) the multiple design alternatives; (4) the complex changing global situation; and (5) the knowledge from the various disciplines comprising the design project. A collective systems thinking approach to design addresses these concerns. Consequently, the theoretical basis of the precautionary principle is directly in line with this approach to design. This presentation will discuss the epistemological and practical implications of the precautionary principle for design in this context
An Epistemological Assessment of Tensions between Expert Evaluations and Qualitative Judgment in Architectural Competitions
How do expert evaluations and expertise impact the outcome of the architectural competitions? What do they bring to the judgment process? This study of experts and expertise in the judgment process originated from our previous study that showed that environmental management tools are shifting the definition of quality in the architectural competition today (Cucuzzella, 2013b). Environmental management tools and certifications are some of the many outcomes of what we refer to today as risk society. This is a society that began in the early 1980\u92s, focused on the assessment and quantification of an array of risks, each with their corresponding set of experts. Among these today, the environmental experts are prominent newcomers in the competition. This paper has three main parts. In the first part, we will circumscribe the various issues related to qualitative judgment in the architectural competition today, specifically with the growing imperatives of sustainability. Here we will also introduce the methodology adopted. Second, we present a series of competitions in order to categorize the types of expert evaluations in the competition today, identify how these impact the jury deliberation and the conflicts they introduce. In the third and largest section, we place this work in the general theory of judgment where we highlight the differences between the expert evaluation of specific project criteria and general qualitative judgment. A critique of the prescriptive and restrictive character of expertise is conducted through a wider theoretical framework. Here we examine the series of observed tensions from a broader epistemological and historical perspective, by looking at the theories of risk society. Here we will reflect on how the emergence of a risk society has changed the way humans deal with uncertainty and how this has led to a rethinking of how we judge the built environment
Environmental standards and judgment processes in competitions for public buildings
No abstract available
Implementing the Precautionary Principle through Stakeholder Engagement for Product and Service Development
The precautionary principle can be integrated into the decision making process during the conception of products and services in a perspective of sustainable development as a complement to Life Cycle Analysis (LCA). This can assist stakeholders in arriving at just and fair decisions based on the complexity and uncertainty of data. LCA provides powerful insights for addressing the environmental aspects of sustainability. Based on an attitude of prevention, LCA seeks to reduce a product’s negative impacts by assessing the various phases of a product’s life-cycle and taking appropriate action. However, in cases of uncertainty of harm, it is not obvious how to define an appropriate course of action because the LCA process is not equipped to deal with a fundamental lack of data. Decisions cannot therefore be easily legitimized. By integrating the precautionary principle through stakeholder engagement, in the perspective of an ethic for the future, such decisions could ultimately be justified and can complement the existing LCA process. This approach becomes pertinent, particularly for stakeholders in their practise of product and service development. Methods such as alternative assessment and precautionary deliberation can assist in this shift towards sustainability
Distributed passivity-based control of DC microgrids
In this paper, we propose a new distributed passivity-based control strategy for Direct Current (DC) microgrids. The considered DC microgrid includes Distributed Generation Units (DGUs) sharing power through resistive-inductive distribution lines. Each DGU is composed of a generic DC energy source that supplies an unknown load through a DC-DC buck converter. The proposed control scheme exploits a communication network, the topology of which can differ from the topology of the physical electrical network, in order to achieve proportional (fair) current sharing using a consensus-like algorithm. Moreover, the proposed distributed control scheme regulates the average value of the network voltages towards the corresponding desired reference, independently of the initial condition of the controlled microgrid. Convergence to a desired steady state is proven and satisfactorily assessed in simulations