405 research outputs found
Itâs All in Marshall: The Impact of External Economies on Regional Dynamics
Marshall's student Pigou noted: âItâs all in Marshall.â From a static point of view, this seems rather bold in a constantly changing world. However, this statement becomes more plausible in a dynamic context, where principles are subject to change. Indeed, over time, Marshall's concept of external economies gained fresh perspective as new concepts of regional characteristics and agglomeration evolved. This paper focuses on the impact of region and industry on dynamics and growth, distinguishing between industrial districts, industrial agglomerations and urban agglomerations. Based on these three types, we use a comprehensive large dataset on German regions to test the following: (1) these regions can be characterized by given location variables describing geographic location, firm structure, and surrounding location factors and (2) every region's locational variables affects its potential for dynamics.regional and urban development, agglomeration, industrial districts, location factors, external economies
Degeneracies between Modified Gravity and Baryonic Physics
In order to determine the observable signatures of modified gravity theories,
it is important to consider the effect of baryonic physics. We use a modified
version of the ISIS code to run cosmological hydrodynamic simulations to study
degeneracies between modified gravity and radiative hydrodynamical processes.
Of these, one was the standard CDM model and four were variations of
the Symmetron model. For each model we ran three variations of baryonic
processes: non-radiative hydrodynamics; cooling and star formation; and
cooling, star formation, and supernova feedback. We construct stacked gas
density, temperature, and dark matter density profiles of the halos in the
simulations, and study the differences between them. We find that both
radiative variations of the models show degeneracies between their processes
and at least two of the three parameters defining the Symmetron model.Comment: 9 pages, 4 figures, matches version accepted to A&
It's all in Marshall: the impact of external economies on regional dynamics
Marshall's student Pigou noted: It's all in Marshall. From a static point of view, this seems rather bold in a constantly changing world. However, this statement becomes more plausible in a dynamic context, where principles are subject to change. Indeed, over time, Marshall's concept of external economies gained fresh perspective as new concepts of regional characteristics and agglomeration evolved. This paper focuses on the impact of region and industry on dynamics and growth, distinguishing between industrial districts, industrial agglomerations and urban agglomerations. Based on these three types, we use a comprehensive large dataset on German regions to test the following: (1) these regions can be characterized by given location variables describing geographic location, firm structure, and surrounding location factors and (2) every region's locational variables affects its potential for dynamics
Generationsgerechtigkeit und Unternehmen
Um der Frage nachgehen zu können, ob Generationengerechtigkeit grundsĂ€tzlich Aufgabe von Unternehmen sein kann, muss zunĂ€chst beantwortet werden, ob Unternehmen als kollektive Akteure moralische Verantwortung tragen können. Dazu wird ein Ansatz vorgestellt, der die SelbstbindungsfĂ€higkeit von Akteuren betont. Unternehmen haben als kollektive Akteure gegenĂŒber Individuen eine gröĂere SelbstbindungsfĂ€higkeit, da sie erstens einen prinzipiell unendlichen Zeithorizont haben; zweitens der Charakter eines korporativen Akteurs durch eine Organisationsverfassung konstituiert wird. Die Bereitschaft von Unternehmen langfristige Investitionen zu tĂ€tigen sowie die glaubhafte Programmierbarkeit des Charakters von Unternehmen kann aber auf Grund verschiedener Unvollkommenheiten eingeschrĂ€nkt sein. Diese Unvollkommenheiten werden im vorliegenden Beitrag ausfĂŒhrlich diskutiert
Uranium Migration in Crystalline Rocks
The mechanisms controlling the migration of uranium in crystalline rocks such as granites or granodiorites are insufficiently well understood to arrive at a quantitatively defensible safety case for deep disposal of radioactive waste. To help further our knowledge of the relevant processes, a controlled column experiment was undertaken using a disc of metallic (depleted) uranium as a source and granodiorite samples from a former candidate disposal site for spent uranium fuel, Sievi in Finland, as the host medium. The experiment ran for approximately 500 days. This report summarises efforts made to simulate the uranium migration observed during the experiment. The model was developed from blind predictions to an inverse model that attempted to reproduce the measured effluent data. In the absence of independently derived kinetic data for uranium precipitation and dissolution it is difficult to arrive at a truly unique solution. Nevertheless, the exercise has been instructive in highlighting the principal areas of uncertainty and the pit falls that await those seeking to represent far more complex hydrogeochemical systems than that investigated here.JRC.F.7-Energy systems evaluatio
Minimising damage to houses by designing for high internal pressures
Internal pressurisation of buildings during a severe wind event, such as a tropical cyclone or thunderstorm, can often cause severe structural failures, as observed during damage investigations. Wind loading standards worldwide provide design data for internal pressure design. However, the implementation of these data often depends on the location of the building in relation to the levels of wind hazard in the relevant country. Recent observations during Tropical Cyclone (TC) Seroja in an intermediate wind region (wind region B) in Western Australia indicated the need for the design for full internal pressures of buildings in this wind region. This paper presents an overview of the damage investigation conducted after TC Seroja that highlights significant damage to buildings due to the lack of design for internal pressures. Additionally, a case study of a house modelled using the vulnerability analysis software VAWS is presented showing the improvements in the performance of buildings designed for internal pressures. TheVAWS models showed that both the design for full internal pressure and the use of debris rated shutters were both effective at reducing the level of serious structural damage and making houses more resilient. The robustness and resilience of buildings increase significantly if they are designed for high internal pressure because the failure of a window or door (a local failure) will not lead to a major structural failure
Generationsgerechtigkeit und Unternehmen
Um der Frage nachgehen zu können, ob Generationengerechtigkeit grundsĂ€tzlich Aufgabe von Unternehmen sein kann, muss zunĂ€chst beantwortet werden, ob Unternehmen als kollektive Akteure moralische Verantwortung tragen können. Dazu wird ein Ansatz vorgestellt, der die SelbstbindungsfĂ€higkeit von Akteuren betont. Unternehmen haben als kollektive Akteure gegenĂŒber Individuen eine gröĂere SelbstbindungsfĂ€higkeit, da sie erstens einen prinzipiell unendlichen Zeithorizont haben; zweitens der Charakter eines korporativen Akteurs durch eine Organisationsverfassung konstituiert wird. Die Bereitschaft von Unternehmen langfristige Investitionen zu tĂ€tigen sowie die glaubhafte Programmierbarkeit des Charakters von Unternehmen kann aber auf Grund verschiedener Unvollkommenheiten eingeschrĂ€nkt sein. Diese Unvollkommenheiten werden im vorliegenden Beitrag ausfĂŒhrlich diskutiert. --
Comparison of Low-Thrust Control Laws for Application in Planetocentric Space
Recent interest at NASA for the application of solar electric propulsion for the transfer of significant payloads in cislunar space has led to the development of high-fidelity simulations of such missions. With such transfers involving transfer times on the order of months, simulation time can be significant. In the past, the examination of such missions typically began with the use of lower-fidelity trajectory optimization tools such as SEPSPOT to develop and tune guidance laws which delivered optimal or near- optimal trajectories, where optimal is generally defined as minimizing propellant expenditure or time of flight. The transfer of these solutions to a high-fidelity simulation is typically an iterative process whereby the initial solution may nearly, but not precisely, meet mission objectives. Further tuning of the guidance algorithm is typically necessary when accounting for high-fidelity perturbations such as those due to more detailed gravity models, secondary-body effects, solar radiation pressure, etc. While trajectory optimization is a useful method for determining optimal performance metrics, algorithms which deliver nearly optimal performance with minimal tuning are an attractive alternative
The Ambivalence of Connexin43 Gap Peptides in Cardioprotection of the Isolated Heart against Ischemic Injury
The present study investigates infarct-reducing effects of blocking ischemia-induced opening of connexin43 hemichannels using peptides Gap19, Gap26 or Gap27. Cardioprotection by ischemic preconditioning (IPC) and Gap peptides was compared, and combined treatment was tested in isolated, perfused male rat hearts using function and infarct size after global ischemia, high-resolution respirometry of isolated mitochondrial and peptide binding kinetics as endpoints. The Gap peptides reduced infarct size significantly when given prior to ischemia plus at reperfusion (Gap19 76.2 ± 2.7, Gap26 72.9 ± 5.8 and Gap27 71.9 ± 5.8% of untreated control infarcts, mean ± SEM). Cardioprotection was lost when Gap26, but not Gap27 or Gap19, was combined with triggering IPC (IPC 73.4 ± 5.5, Gap19-IPC 60.9 ± 5.1, Gap26-IPC 109.6 ± 7.8, Gap27-IPC 56.3 ± 8.0% of untreated control infarct). Binding stability of peptide Gap26 to its specific extracellular loop sequence (EL2) of connexin43 was stronger than Gap27 to its corresponding loop EL1 (dissociation rate constant Kd 0.061 ± 0.004 vs. 0.0043 ± 0.0001 sâ1 , mean ± SD). Mitochondria from IPC hearts showed slightly but significantly reduced respiratory control ratio (RCR). In vitro addition of Gap peptides did not significantly alter respiration. If transient hemichannel activity is part of the IPC triggering event, inhibition of IPC triggering stimuli might limit the use of cardioprotective Gap peptides
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