Geometric phase and gauge theory structure in quantum computing

We discuss the presence of a geometrical phase in the evolution of a qubit state and its gauge structure. The time evolution operator is found to be the free energy operator, rather than the Hamiltonian operator.Comment: 5 pages, presented at Fifth International Workshop DICE2010: Space-Time-Matter - current issues in quantum mechanics and beyond, Castiglioncello (Tuscany), September 13-17, 201

Mapping prior information onto LMI eigenvalue-regions for discrete-time subspace identification

In subspace identification, prior information can be used to constrain the eigenvalues of the estimated state-space model by defining corresponding LMI regions. In this paper, first we argue on what kind of practical information can be extracted from historical data or step-response experiments to possibly improve the dynamical properties of the corresponding model and, also, on how to mitigate the effect of the uncertainty on such information. For instance, prior knowledge regarding the overshoot, the period between damped oscillations and settling time may be useful to constraint the possible locations of the eigenvalues of the discrete-time model. Then, we show how to map the prior information onto LMI regions and, when the obtaining regions are non-convex, to obtain convex approximations.Comment: Under revie

An ab-initio theoretical investigation of the soft-magnetic properties of permalloys

We study Ni80Fe20-based permalloys with the relativistic spin-polarized Korringa-Kohn-Rostoker electronic structure method. Treating the compositional disorder with the coherent potential approximation, we investigate how the magnetocrystalline anisotropy, K, and magnetostriction, lambda, of Ni-rich Ni-Fe alloys vary with the addition of small amounts of non-magnetic transition metals, Cu and Mo. From our calculations we follow the trends in K and lambda and find the compositions of Ni-Fe-Cu and Ni-Fe-Mo where both are near zero. These high permeability compositions of Ni-Fe-Cu and Ni-Fe-Mo match well with those discovered experimentally. We monitor the connection of the magnetic anisotropy with the number of minority spin electrons, Nmin. By raising Nmin via artificially increasing the band-filling of Ni80Fe20, we are able to reproduce the key features that underpin the magnetic softening we find in the ternary alloys. The effect of band-filling on the dependence of magnetocrystalline anisotropy on atomic short-range order in Ni80Fe20 is also studied. Our calculations, based on a static concentration wave theory, indicate that the susceptibility of the high permeability of the Ni-Fe-Cu and Ni-Fe-Mo alloys to their annealing conditions is also strongly dependent on the alloys' compositions. An ideal soft magnet appears from these calculations.Comment: 20 pages, 6 figure

Noblesse Oblige? Determinants of Survival in a Life and Death Situation

This paper explored the determinants of survival in a life and death situation created by an external and unpredictable shock. We are interested to see whether pro-social behaviour matters in such extreme situations. We therefore focus on the sinking of the RMS Titanic as a quasi-natural experiment do provide behavioural evidence which is rare in such a controlled and life threatening event. The empirical results support that social norm such as �women and children first� survive in such an environment. We also observe that women of reproductive age have a higher probability of surviving among women. On the other hand, we observe that crew members used their information advantage and their better access to resources (e.g. lifeboats) to generate a higher probability of surviving. The paper also finds that passenger class, fitness, group size, and cultural background matter.Decision under Pressure, Altruism, Social Norms, Interdependent Preferences, Excess of Demand

Surviving the Titanic Disaster: Economic, Natural and Social Determinants

The sinking of the Titanic in April 1912 took the lives of 68 percent of the people aboard. Who survived? It was women and children who had a higher probability of being saved, not men. Likewise, people traveling in first class had a better chance of survival than those in second and third class. British passengers were more likely to perish than members of other nations.This extreme event represents a rare case of a well-documented life and death situation where social norms were enforced. This paper shows that economic analysis can account for human behavior in such situations.decision under pressure, tragic events and disasters, survival, quasi-natural experiment, altruism

Surviving the Titanic Disaster: Economic, Natural and Social Determinants

The sinking of the Titanic in April 1912 took the lives of 68 percent of the people aboard. Who survived? It was women and children who had a higher probability of being saved, not men. Likewise, people traveling in first class had a better chance of survival than those in second and third class. British passengers were more likely to perish than members of other nations. This extreme event represents a rare case of a well-documented life and death situation where social norms were enforced. This paper shows that economic analysis can account for human behavior in such situations.Decision under Pressure, Tragic Events and Disasters, Survival, Quasi-Natural Experiment, Altruism

On the Logarithmic Asymptotics of the Sixth Painleve' Equation (Summer 2007)

We study the solutions of the sixth Painlev\'e equation with a logarithmic asymptotic behavior at a critical point. We compute the monodromy group associated to the solutions by the method of monodromy preserving deformations and we characterize the asymptotic behavior in terms of the monodromy itself.Comment: LaTeX with 8 figure

Noblesse Oblige? Determinants of Survival in a Life and Death Situation

This paper explored the determinants of survival in a life and death situation created by an external and unpredictable shock. We are interested to see whether pro-social behaviour matters in such extreme situations. We therefore focus on the sinking of the RMS Titanic as a quasi-natural experiment do provide behavioural evidence which is rare in such a controlled and life threatening event. The empirical results support that social norm such as “women and children first” survive in such an environment. We also observe that women of reproductive age have a higher probability of surviving among women. On the other hand, we observe that crew members used their information advantage and their better access to resources (e.g. lifeboats) to generate a higher probability of surviving. The paper also finds that passenger class, fitness, group size, and cultural background matter.decision under pressure, altruism, social norms, interdependent preferences, excess of demand