417 research outputs found
Electricity, carbon and weather in France: where do we stand ?
As a tool to fight long run changes in climate the European Union explicitly introduced the emission trading scheme (EU ETS) on January 1, 2005, which aimed at reducing carbon emission by 8% by 2012, and was designed to operate in two phases. Using data related to the first phase, this article investigates the role that the EU ETS plays in the power generation market by taking into account the existence of possible cross-spillovers between the French carbon and the French electricity spot markets, the spot prices of natural gas and of oil, and climatic conditions in France and elsewhere. Results show that there is no short run relationship between the electricity and carbon returns, while there is a long run relationship. However, this relationship suffers from a disequilibrium in that the electricity price readjust in the long run. We also find that while there are own mean and own volatility spillovers in the two markets, there are no cross own mean and own volatility spillovers, indicating that the electricity spot market and the carbon spot market are not integrated. Finally, results underline the limited impact of weather on the interconnection of these markets.Carbon market, Electricity, Weather, Multivariate GARCH
Beyond the standard gauging: gauge symmetries of Dirac Sigma Models
In this paper we study the general conditions that have to be met for a
gauged extension of a two-dimensional bosonic sigma-model to exist. In an
inversion of the usual approach of identifying a global symmetry and then
promoting it to a local one, we focus directly on the gauge symmetries of the
theory. This allows for action functionals which are gauge invariant for rather
general background fields in the sense that their invariance conditions are
milder than the usual case. In particular, the vector fields that control the
gauging need not be Killing. The relaxation of isometry for the background
fields is controlled by two connections on a Lie algebroid L in which the gauge
fields take values, in a generalization of the common Lie-algebraic picture.
Here we show that these connections can always be determined when L is a Dirac
structure in the H-twisted Courant algebroid. This also leads us to a
derivation of the general form for the gauge symmetries of a wide class of
two-dimensional topological field theories called Dirac sigma-models, which
interpolate between the G/G Wess-Zumino-Witten model and the (Wess-Zumino-term
twisted) Poisson sigma model.Comment: 1+27 pages; version 2: minor correction in the introduction; version
3: minor corrections to match published version, references updated,
acknowledgement adde
Gauging as constraining: the universal generalised geometry action in two dimensions
One of the central concepts in modern theoretical physics, gauge symmetry, is
typically realised by lifting a finite-dimensional global symmetry group of a
given functional to an infinite-dimensional local one by extending the
functional to include gauge fields. In this contribution we review the
construction of gauged actions for two-dimensional sigma models, considering a
more general notion to be gauged, namely that of a (possibly singular)
foliation. In particular, the original action does not need to have any global
symmetry for this purpose. Moreover, reformulating the ungauged theory by means
of auxiliary 1-form fields taking values in the generalised tangent bundle over
the target, all possible such gauge theories result from restriction of these
fields to take values in (possibly small) Dirac structures. This turns all the
remaining 1-form fields into gauge fields and leads to the presence of a local
symmetry. We recall all needed mathematical notions, those of (higher) Lie
algebroids, Courant algebroids, and Dirac structures.Comment: 20 pages; proceedings of "Recent Developments in Strings and
Gravity", Corfu Summer Institute 201
Electricity, carbon and weather in France: where do we stand ?
As a tool to fight long run changes in climate the European Union explicitly introduced the emission trading scheme (EU ETS) on January 1, 2005, which aimed at reducing carbon emission by 8% by 2012, and was designed to operate in two phases. Using data related to the first phase, this article investigates the role that the EU ETS plays in the power generation market by taking into account the existence of possible cross-spillovers between the French carbon and the French electricity spot markets, the spot prices of natural gas and of oil, and climatic conditions in France and elsewhere. Results show that there is no short run relationship between the electricity and carbon returns, while there is a long run relationship. However, this relationship suffers from a disequilibrium in that the electricity price readjust in the long run. We also find that while there are own mean and own volatility spillovers in the two markets, there are no cross own mean and own volatility spillovers, indicating that the electricity spot market and the carbon spot market are not integrated. Finally, results underline the limited impact of weather on the interconnection of these markets
Ketogenic diet and fasting diet as Nutritional Approaches in Multiple Sclerosis (NAMS): protocol of a randomized controlled study
BACKGROUND:
Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system in young adults that may lead to progressive disability. Since pharmacological treatments may have substantial side effects, there is a need for complementary treatment options such as specific dietary approaches. Ketone bodies that are produced during fasting diets (FDs) and ketogenic diets (KDs) are an alternative and presumably more efficient energy source for the brain. Studies on mice with experimental autoimmune encephalomyelitis showed beneficial effects of KDs and FDs on disease progression, disability, cognition and inflammatory markers. However, clinical evidence on these diets is scarce. In the clinical study protocol presented here, we investigate whether a KD and a FD are superior to a standard diet (SD) in terms of therapeutic effects and disease progression.
METHODS:
This study is a single-center, randomized, controlled, parallel-group study. One hundred and eleven patients with relapsing-remitting MS with current disease activity and stable immunomodulatory therapy or no disease-modifying therapy will be randomized to one of three 18-month dietary interventions: a KD with a restricted carbohydrate intake of 20-40 g/day; a FD with a 7-day fast every 6 months and 14-h daily intermittent fasting in between; and a fat-modified SD as recommended by the German Nutrition Society. The primary outcome measure is the number of new T2-weighted MRI lesions after 18 months. Secondary endpoints are safety, changes in relapse rate, disability progression, fatigue, depression, cognition, quality of life, changes of gut microbiome as well as markers of inflammation, oxidative stress and autophagy. Safety and feasibility will also be assessed.
DISCUSSION:
Preclinical data suggest that a KD and a FD may modulate immunity, reduce disease severity and promote remyelination in the mouse model of MS. However, clinical evidence is lacking. This study is the first clinical study investigating the effects of a KD and a FD on disease progression of MS
Disease modification in multiple sclerosis by flupirtine-results of a randomized placebo controlled phase II trial
Central nervous system inflammation and neurodegeneration are the pathophysiological hallmarks of multiple sclerosis (MS). While inflammation can readily be targeted by current disease modifying drugs, neurodegeneration is by far less accessible to treatment. Based on suggested additional neuroprotective capacities of the orally available non-opioid and centrally acting analgesic drug flupirtine maleate we hypothesized that treatment with flupirtine maleate might be beneficial in MS patients. The flupirtine as oral treatment in multiple sclerosis (FLORIMS) study was a multi-center, randomized and stratified, placebo-controlled double-blind phase II trial to investigate safety and efficacy in terms of clinical and radiographical activity of flupirtine maleate (300 mg per day) given orally for 12 months, add-on to interferon beta 1b subcutaneously in patients with relapsing remitting MS. Due to a substantial delay in recruitment, enrolment of patients was prematurely terminated after randomization of only 30 of the originally planned 80 patients. Of these, 24 regularly terminated study after 12 months of treatment. Data were analyzed as originally planned. Treatment with flupirtine maleate was overall well tolerated. We observed moderate and asymptomatic elevations of liver enzymes in several cases but no overt hepatotoxicity. Neither the intention to treat nor the per protocol analysis revealed any significant treatment effects of flupirtine maleate with respect to occurrence of MS relapses, disability progression, or development of new lesions on cranial MRI. However, substantial methodological limitations need to be considered when interpreting these results. In conclusion, the results of the FLORIMS study neither add further evidence to nor argue against the hypothesized neuroprotective or disease modifying effects of flupirtine maleate in MS
Do mountain tourists demand ecotourism? Examining moderating influences in an Alpine tourism context
Ecotourists appreciate nature and are willing to learn about nature and ecology. Therefore ecotourism is often seen as a product package that supports sustainable tourism development. This study contributes to existing research in the field of ecotourism as it investigates how travel motives and environmental concern of mountain tourists influences their actual demand for ecotourism. A survey of mountain tourists in the Austrian Alps was conducted and reveals a positive relationship between environmental concern and ecotourism demand. The study measured travel motives, which are compatible and incompatible with ecotourism and showed how these motives influence actual demand of ecotourism. Furthermore it is postulated that education, income and the intention to revisit the destination moderate the relationship between environmental concern, mountain tourists’ motives and the tourists’ demand for ecotourism. For destination marketing it can be stated that higher educated mountain tourists with a high disposable income are a vital market segment, which should be targeted for ecotourism in the mountains. Research recommendations are highlighted and focus on loyal visitors, as it remains unclear whether loyalty with an ecotourism destination strengthens the demand for ecotourism
The price impact of extreme weather in developing countries
We examine the impact of extreme weather on consumer prices in developing countries by constructing a monthly data set of potential hurricane and flood destruction indices and linking these with consumer price data for 15 Caribbean islands. Our econometric model shows that the price impact of extreme weather events can be large. To illustrate potential welfare losses due to these price effects, we combine our estimates with price elasticities obtained from a demand system and with event probabilities for Jamaica. Our results show that while expected monthly losses are small, rare events can cause large falls in monthly welfare due to price increases
From the Behavior Model of an Animated Visual Language to its Editing Environment Based on Graph Transformation
Animated visual models are a reasonable means for illustrating system behavior. However, implementing animated visual languages and their editing environments is difficult. Therefore, guidelines, specification methods, and tool support are necessary. A flexible approach for specifying model states and behavior is to use graphs and graph transformations. Thereby, a graph can also represent dynamic aspects of a model, like animations, and graph transformations are triggered over time to control the behavior, like starting, modifying, and stopping animations or adding and removing elements. These concepts had already been added to Dia-Meta, a framework for generating editing environments, but they provide only low-level support for specifying and implementing animated visual languages; specifying complex dynamic languages was still a challenging task. This paper proposes the Animation Modeling Language (AML), which allows to model behavior and animations on a higher level of abstraction. AML models are then translated into low-level specifications based on graph transformations. The approach is demonstrated using a traffic simulation
Entrepreneurial Leadership in Austrian Family SMEs:A Configurational Approach
This article explores the role of stewardship practices related to entrepreneurial leadership in turning entrepreneurial orientation (EO) into family firm performance while considering its environmental context. Family business research has not fully investigated how the EO–financial performance relationship depends on configurations of internal and external factors which establish strategic fit. We argue that family firms can overcome the often- highlighted paternalism-entrepreneurship paradox by employing stewardship practices related to entrepreneurial leadership (internal factor), which in turn can help them leverage strategic fit between EO and dynamic environments (external factor). The results of a survey of 162 Austrian small and medium-sized family enterprises (family SMEs) show that family SMEs can only profit from EO under certain configurations of internal and external factors. Employing stewardship practices related to entrepreneurial leadership turns out to be an efficient and necessary condition for transforming EO into performance. Environmental dynamism is, furthermore, a double-edged sword facilitating and impeding the transformation of EO into performance. These findings contribute to existing research by shedding light on the role of stewardship practices in establishing strategic fit in entrepreneurial family firms
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