Oscillating Ornstein-Uhlenbeck processes and modelling of electricity prices

In this paper we propose an alternative model for electricity spot prices based on oscillating Ornstein-Uhlenbeck processes. This model captures the characteristics of empirical data, especially the oscillating shape of the autocorrelation function. Furthermore, we show that our model leads to explicit formulas for forwards and options on forwards

Oscillating Ornstein-Uhlenbeck processes and modelling of electricity prices

In this paper we propose an alternative model for electricity spot prices based on oscillating Ornstein-Uhlenbeck processes. This model captures the characteristics of empirical data, especially the oscillating shape of the autocorrelation function. Furthermore, we show that our model leads to explicit formulas for forwards and options on forwards

Ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfishScarus zelindae

Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals. Thus, terminal phase individuals forage with lower feeding rates compared to juveniles and initial phase individuals. The highest relative foraging frequency of S. zelindae was on epilithic algae matrix (EAM) with similar values for juveniles (86.6%), initial phase (88.1%) and terminal phase (88.6%) individuals. The second preferred benthos for juveniles was sponge (11.6%) compared with initial (4.5%) and terminal life phases (1.3%). Different life phases of S. zelindae foraged on different benthos according to their availability. Based on Ivlev's electivity index, juveniles selected EAM and sponge, while initial phase and terminal phase individuals only selected EAM. Our findings demonstrate that the foraging frequency of the endemic parrotfish S. zelindae is reduced according to body size and that there is a slight ontogenetic change in feeding selectivity. Therefore, ecological knowledge of ontogenetic variations on resource use is critical for the remaining parrotfish populations which have been dramatically reduced in the Southwestern Atlantic Ocean

Arteriosclerotic Calcification and Atrial Fibrillation in the General Population:The Rotterdam Study

Limited population-based data on the gender differences and association between arteriosclerotic calcification at different sites and atrial fibrillation (AF) exist. We aimed to investigate the (gender-specific) associations between arteriosclerotic calcification at different sites with the risk of AF in the general population. Arteriosclerotic calcification was quantified using computed tomography examinations between 2003 and 2006 in 2,259 participants free of AF from the population-based Rotterdam Study. Cox proportional hazards models, adjusted for cardiovascular risk factors, were used to assess the associations of volumes of coronary artery calcification (CAC), aortic arch calcification (AAC), extracranial and intracranial carotid arteries, vertebrobasilar arteries, and the aortic valve with incident AF. During a median follow-up of 8.6 years, 182 incident AF cases occurred. A larger CAC was associated with incident AF (hazard ratio [HR], 95% confidence interval [CI] 1.25 1.09 to 1.44, p = 0.0019). The gender-stratified analyses showed that larger CAC in men (HR 1.43, 95% CI 1.10 to 1.86, p = 0.0068) and larger AAC in women were associated with incident AF (HR1.44, 95% CI 1.04 to 2.01, p = 0.0299). In conclusion, CAC in the general population, especially in men, and AAC in women were significantly associated with new-onset AF. Our findings imply that interventions to lower arteriosclerotic calcification, particularly, CAC, carry potential for the prevention of AF in the general population, especially in men.</p

The Minimal Supersymmetric Fat Higgs Model

We present a calculable supersymmetric theory of a composite ``fat'' Higgs boson. Electroweak symmetry is broken dynamically through a new gauge interaction that becomes strong at an intermediate scale. The Higgs mass can easily be 200-450 GeV along with the superpartner masses, solving the supersymmetric little hierarchy problem. We explicitly verify that the model is consistent with precision electroweak data without fine-tuning. Gauge coupling unification can be maintained despite the inherently strong dynamics involved in electroweak symmetry breaking. Supersymmetrizing the Standard Model therefore does not imply a light Higgs mass, contrary to the lore in the literature. The Higgs sector of the minimal Fat Higgs model has a mass spectrum that is distinctly different from the Minimal Supersymmetric Standard Model.Comment: 13 pages, 5 figures, REVTe

Neutrino Interferometry In Curved Spacetime

Gravitational lensing introduces the possibility of multiple (macroscopic) paths from an astrophysical neutrino source to a detector. Such a multiplicity of paths can allow for quantum mechanical interference to take place that is qualitatively different to neutrino oscillations in flat space. After an illustrative example clarifying some under-appreciated subtleties of the phase calculation, we derive the form of the quantum mechanical phase for a neutrino mass eigenstate propagating non-radially through a Schwarzschild metric. We subsequently determine the form of the interference pattern seen at a detector. We show that the neutrino signal from a supernova could exhibit the interference effects we discuss were it lensed by an object in a suitable mass range. We finally conclude, however, that -- given current neutrino detector technology -- the probability of such lensing occurring for a (neutrino-detectable) supernova is tiny in the immediate future.Comment: 25 pages, 1 .eps figure. Updated version -- with simplified notation -- accepted for publication in Phys.Rev.D. Extra author adde

Transverse phase-locking in fully frustrated Josephson junction arrays: a new type of fractional giant steps

We study, analytically and numerically, phase locking of driven vortex lattices in fully-frustrated Josephson junction arrays at zero temperature. We consider the case when an ac current is applied {\it perpendicular} to a dc current. We observe phase locking, steps in the current-voltage characteristics, with a dependence on external ac-drive amplitude and frequency qualitatively different from the Shapiro steps, observed when the ac and dc currents are applied in parallel. Further, the critical current increases with increasing transverse ac-drive amplitude, while it decreases for longitudinal ac-drive. The critical current and the phase-locked current step width, increase quadratically with (small) amplitudes of the ac-drive. For larger amplitudes of the transverse ac-signal, we find windows where the critical current is hysteretic, and windows where phase locking is suppressed due to dynamical instabilities. We characterize the dynamical states around the phase-locking interference condition in the $IV$ curve with voltage noise, Lyapunov exponents and Poincar\'e sections. We find that zero temperature phase-locking behavior in large fully frustrated arrays is well described by an effective four plaquette model.Comment: 12 pages, 11 figure

Reconciling Neutralino Relic Density with Yukawa Unified Supersymmetric Models

Supersymmetric grand unified models based on the gauge group SO(10) are especially attractive in light of recent data on neutrino masses. The simplest SO(10) SUSY GUT models predict unification of third generation Yukawa couplings in addition to the usual gauge coupling unification. Recent surveys of Yukawa unified SUSY GUT models predict an inverted scalar mass hierarchy in the spectrum of sparticle masses if the superpotential mu term is positive. In general, such models tend to predict an overabundance of dark matter in the universe. We survey several solutions to the dark matter problem in Yukawa unified supersymmetric models. One solution-- lowering the GUT scale mass value of first and second generation scalars-- leads to u_R and c_R squark masses in the 90-120 GeV regime, which should be accessible to Fermilab Tevatron experiments. We also examine relaxing gaugino mass universality which may solve the relic density problem by having neutralino annihilations via the Z or h resonances, or by having a wino-like LSP.Comment: 21 page file plus 9 figures; updated version to coincide with published versio