8,829 research outputs found
The influence of strong magnetic fields and instantons on the phase structure of the two-flavor NJL model
Both in heavy-ion collisions as in magnetars very strong magnetic fields are
produced, which has its influence on the phases of matter involved. In this
paper we investigate the effect of strong magnetic fields (B = 5 m_pi^2 /e =
1.7 x 10^19 G) on the chiral symmetry restoring phase transition using the
Nambu-Jona-Lasinio model. It is observed that the pattern of phase transitions
depends on the relative magnitude of the magnetic field and the instanton
interaction strength. We study two specific regimes in the phase diagram, high
chemical potential and zero temperature and vice versa, which are of relevance
for neutron stars and heavy-ion collisions respectively. In order to shed light
on the behavior of the phase transitions we study the dependence of the minima
of the effective potential on the occupation of Landau levels. We observe a
near-degeneracy of multiple minima with differing occupation numbers, of which
some become the global minimum upon changing the magnetic field or the chemical
potential. These minima differ considerably in the amount of chiral symmetry
breaking and in some cases also of isospin breaking.Comment: 11 pages, 8 figures, references added and some minor change
Impact of Forecast Errors on Expansion Planning of Power Systems with a Renewables Target
This paper analyzes the impact of production forecast errors on the expansion
planning of a power system and investigates the influence of market design to
facilitate the integration of renewable generation. For this purpose, we
propose a stochastic programming modeling framework to determine the expansion
plan that minimizes system-wide investment and operating costs, while ensuring
a given share of renewable generation in the electricity supply. Unlike
existing ones, this framework includes both a day-ahead and a balancing market
so as to capture the impact of both production forecasts and the associated
prediction errors. Within this framework, we consider two paradigmatic market
designs that essentially differ in whether the day-ahead generation schedule
and the subsequent balancing re-dispatch are co-optimized or not. The main
features and results of the model set-ups are discussed using an illustrative
four-node example and a more realistic 24-node case study
Feedback in Galaxy Formation
I review the outstanding problems in galaxy formation theory, and the role of
feedback in resolving them. I address the efficiency of star formation, the
galactic star formation rate, and the roles of supernovae and supermassive
black holes.Comment: To appear in the proceedings of IAU Symposium 277, Burkina Faso,
December 2010, Tracing the Ancestry of Galaxies (on the Land of our
Ancestors), C. Carignan, F. Combes \& K. Freeman, ed
Effects of instanton interactions on the phases of quark matter
Mulders, P.J.G. [Promotor]Boer, D. [Copromotor
High Velocity Gas in the Halos of Spiral Galaxies
Recent, high sensitivity, HI observations of nearby spiral galaxies show that
their thin `cold' disks are surrounded by thick layers (halos) of neutral gas
with anomalous kinematics. We present results for three galaxies viewed at
different inclination angles: NGC891 (edge-on), NGC2403 (i=60 deg), and NGC6946
(almost face-on). These studies show the presence of halo gas up to distances
of 10-15 kpc from the plane. Such gas has a mean rotation 25-50 km/s lower than
that of the gas in the plane, and some complexes are detected at very high
velocities, up to 200-300 km/s. The nature and origin of this halo gas are
poorly understood. It can either be the result of a galactic fountain or of
accretion from the intergalactic medium. It is probably the analogous of some
of the High Velocity Clouds (HVCs) of the Milky Way.Comment: 6 pages, 4 figures. To appear in the ASP proceedings of IAU Symposium
217, "Recycling intergalactic and interstellar matter", eds. Pierre-Alain
Duc, Jonathan Braine, Elias Brink
Renalase, a catecholamine-metabolising enzyme?
Recently, a new FAD-dependent amine oxidase, renalase, was described. It was secreted by the kidney into the blood and shown to have significant cardiovascular actions, which were attributed to its catecholamine-metabolising activity. The authors concluded that renalase might be an important regulatory factor in human (patho)physiology. The catecholamine-metabolising activity of renalase in plasma contrasts with previous investigations where catecholamines were found to be stable in human plasma, provided autoxidation is prevented by an antioxidant. The claim of catecholamine-metabolising activity of renalase was based on the generation of H2O2 during incubation of the enzyme with catecholamines. Careful inspection and calculations of the data lead to the conclusion that the rate of H2O2 generation is far too low to be ascribed to enzymatic conversion of catecholamines by renalase. Renalase may well have important cardiovascular functions, but there is no proof that its actions are mediated through catecholamine-metabolising activity
On the transition to a sustainable economy:Field experimental evidence on behavioral interventions
This dissertation studies the impact of behavioral interventions on waste sorting and energy conservation, two domains where sustained environmental conservation has the potential to substantially reduce social costs. The interventions are evaluated by means of field experiments. The first essay investigates the relative impact of behavioral interventions versus neoclassical interventions. It finds that interventions that draw on extrinsic motivations have an immediate and sizable effect on waste sorting behavior, but also that the average treatment effects attenuate steeply over time. In contrast, the essay finds equally sizeable yet long-lasting effects of a treatment designed to increase households' intrinsic motivation to sort waste. The second essay analyzes the effect of social learning interventions. It considers two interventions, one aimed at leveraging social learning via role models and a second one via feedback on the prevalence of organic waste sorting in the household's direct vicinity. The essay finds that both interventions increase waste sorting in the short run, but only the social feedback's impact is long-lasting. The third essay analyzes residential energy consumption, and how real-time disaggregated consumption feedback corrects consumer mistakes in this domain. The essay finds this feedback, provided by way of in-home displays, to reduce household energy consumption. The savings are largest on gas consumption, and the evidence suggests the effect to reflect reductions in space heating. The three essays are preceded by an introductory chapter that introduces the topic of study and the field experimental methodology. The dissertation closes with a concluding chapter that reviews its contribution to the literature on behavioral interventions and its implications for Dutch environmental policy
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