Distribution of eigenstate populations and dissipative beating dynamics in uniaxial single-spin magnets

Numerical simulations of magnetization reversal of a quantum uniaxial magnet under a swept magnetic field [Hatomura, \textit{et al}., \textit{Quantum Stoner-Wohlfarth Model}, Phys. Rev. Lett. \textbf{116}, 037203 (2016)] are extended. In particular, how the "wave packet" describing the time-evolution of the system is scattered in the successive avoided level crossings is investigated from the viewpoint of the distribution of the eigenstate populations. It is found that the peak of the distribution as a function of the magnetic field does not depend on spin-size $S$, which indicates that the delay of magnetization reversal due to the finite sweeping rate is the same in both the quantum and classical cases. The peculiar synchronized oscillations of all the spin components result in the beating of the spin-length. Here, dissipative effects on this beating are studied by making use of the generalized Lindblad-type master equation. The corresponding experimental situations are also discussed in order to find conditions for experimental observations

Quantum Stoner-Wohlfarth model

The quantum mechanical counterpart of the famous Stoner-Wohlfarth model -- an easy-axis magnet in a tilted magnetic field -- is studied theoretically and through simulations, as a function of the spin-size $S$ in a sweeping longitudinal field. Beyond the classical Stoner-Wohlfarth transition, the sweeping field-induced adiabatic change of states slows down as $S$ increases, leading to a dynamical quantum phase transition. This result is described as a critical phenomenon associated with Landau-Zener tunneling gaps at metastable quasi-avoided crossings. Furthermore, a beating of the magnetization is discovered after the Stoner-Wohlfarth transition. The period of the beating, obtained analytically, arises from a new type of quantum phase factor.Comment: 4 pages, 6 figure

A bounded jump for the bounded Turing degrees

We define the bounded jump of A by A^b = {x | Exists i <= x [phi_i (x) converges and Phi_x^[A|phi_i(x)](x) converges} and let A^[nb] denote the n-th bounded jump. We demonstrate several properties of the bounded jump, including that it is strictly increasing and order preserving on the bounded Turing (bT) degrees (also known as the weak truth-table degrees). We show that the bounded jump is related to the Ershov hierarchy. Indeed, for n > 1 we have X <=_[bT] 0^[nb] iff X is omega^n-c.e. iff X <=_1 0^[nb], extending the classical result that X <=_[bT] 0' iff X is omega-c.e. Finally, we prove that the analogue of Shoenfield inversion holds for the bounded jump on the bounded Turing degrees. That is, for every X such that 0^b <=_[bT] X <=_[bT] 0^[2b], there is a Y <=_[bT] 0^b such that Y^b =_[bT] X.Comment: 22 pages. Minor changes for publicatio

Reduced basis methods for pricing options with the Black-Scholes and Heston model

In this paper, we present a reduced basis method for pricing European and American options based on the Black-Scholes and Heston model. To tackle each model numerically, we formulate the problem in terms of a time dependent variational equality or inequality. We apply a suitable reduced basis approach for both types of options. The characteristic ingredients used in the method are a combined POD-Greedy and Angle-Greedy procedure for the construction of the primal and dual reduced spaces. Analytically, we prove the reproduction property of the reduced scheme and derive a posteriori error estimators. Numerical examples are provided, illustrating the approximation quality and convergence of our approach for the different option pricing models. Also, we investigate the reliability and effectivity of the error estimators.Comment: 25 pages, 27 figure

Louis Néel: His multifaceted seminal work in magnetism

International audienc

Using Happiness Surveys to Value Intangibles: The Case of Airport Noise

Inhabitants of houses near Amsterdam Airport are complaining of noise nuisance, caused by aircraft traffic. The usual assumption is that the effect of the externality will be perfectly reflected by house price differentials. This is based on the implicit assumption that there is a well-functioning housing market. If that is not true, we need a correction method in order to assess the intangible damage. We assess the monetary value of the noise damage, caused by aircraft noise nuisance around Amsterdam Airport as the sum of hedonic price differentials and a residual cost component. The residual costs are assessed from a survey, including an ordinal life satisfaction scale, on which individual respondents have scored. The derived compensation scheme depends on, among other things, the objective noise level, income, the degree to which prices account for noise differences, and the presence of noise insulation.cost-benefit analysis, externalities, airport noise, satisfaction analysis, residual shadow costs

Audit on follow-up of patients with primary Osteoporosis

Aim: To document the frequency of Dual-energy X- ray absorptiometry (DEXA) scanning and Rheumatology clinic follow-up visits of patients with primary osteoporosis, and compare these with recommended guidelines. Method: Medical notes of all primary osteoporotic patients attending a hospital Rheumatology clinic were reviewed over a period of four months. Data was collected on age, gender, frequency of follow up visits, frequency of DEXA scanning, osteoporosis treatment, any changes in such treatment during the last visit, and comparison of the last two DEXA scan results. Frequency of follow up DEXA scans was compared to Group Health Osteoporosis Screening Diagnosis and Treatment guidelines.1 Results: Eighty-two patients were included, 6 males (7.3%) and 76 females (92.7%). The age range was 35-87 years (mean age was 68.6 years). In total, 42.7% of all the patients were on combined calcium and vitamin D, with added Bisphosphonates, Strontium ranelate, or Denosumab. During their last clinic visit, 61% showed improvement in T score since their previous result, and 64.6% of patients had no change in treatment. In this audit, 29.3% were being followed up on a 13 monthly basis, and 72% had annual bone mineral density scans or more frequently Conclusion: According to the guidelines, none of the patients included in this audit should have had a repeat DEXA scan within less than two years. Patients attending the clinic have too frequent DEXA scans and therefore, too frequent follow up appointments.peer-reviewe