The hedonic placebo effect of traditional medicines

To date, the scientific evidence on traditional medicines is scant and under-developed, yet, paradoxically individuals continue to use it and claim high satisfaction levels. What can explain this effect? Using self-collected data from Ghana we argue that variations in satisfaction across individuals can be attributed to the hedonic placebo effect gained from using traditional medicines, in which processes involved with its consumption are as important, if not more important, than measures of self-reported health outcome. Findings suggest that individuals’ health seeking behaviour should be evaluated using procedural, as well as outcome, utility

A remark on zeta functions of finite graphs via quantum walks

From the viewpoint of quantum walks, the Ihara zeta function of a finite graph can be said to be closely related to its evolution matrix. In this note we introduce another kind of zeta function of a graph, which is closely related to, as to say, the square of the evolution matrix of a quantum walk. Then we give to such a function two types of determinant expressions and derive from it some geometric properties of a finite graph. As an application, we illustrate the distribution of poles of this function comparing with those of the usual Ihara zeta function.Comment: 14 pages, 1 figur

Fitting two nucleons inside a box: exponentially suppressed corrections to the Luscher's formula

Scattering observables can be computed in lattice field theory by measuring the volume dependence of energy levels of two particle states. The dominant volume dependence, proportional to inverse powers of the volume, is determined by the phase shifts. This universal relation (\Lu's formula) between energy levels and phase shifts is distorted by corrections which, in the large volume limit, are exponentially suppressed. They may be sizable, however, for the volumes used in practice and they set a limit on how small the lattice can be in these studies. We estimate these corrections, mostly in the case of two nucleons. Qualitatively, we find that the exponentially suppressed corrections are proportional to the {\it square} of the potential (or to terms suppressed in the chiral expansion) and the effect due to pions going ``around the world'' vanishes. Quantitatively, the size of the lattice should be greater than $\approx(5 {fm})^3$ in order to keep finite volume corrections to the phase less than $1^\circ$ for realistic pion mass.Comment: 18 pages, 5 figures, 6 figure

Some Observations for Mean-Field Spin Glass Models

We obtain bounds to show that the pressure of a two-body, mean-field spin glass is a Lipschitz function of the underlying distribution of the random coupling constants, with respect to a particular semi-norm. This allows us to re-derive a result of Carmona and Hu, on the universality of the SK model, by a different proof, and to generalize this result to the Viana-Bray model. We also prove another bound, suitable when the coupling constants are not independent, which is what is necessary if one wants to consider ``canonical'' instead of ``grand canonical'' versions of the SK and Viana-Bray models. Finally, we review Viana-Bray type models, using the language of L\'evy processes, which is natural in this context.Comment: 15 pages, minor revision

Does culture matter at all in explaining why people still use traditional medicines?

Why do individuals still use traditional medicines when modern treatments are available? Economic explanations for an individual’s use of traditional instead of modern medicines are scarce and often fail to consider explanations beyond the conventional. This paper puts forward an economic explanation for the use of traditional medicine. First, traditional medicines were the default form of health care available in pre-colonial times where industry influence was yet to develop. Hence, both those individuals who exhibit lower incomes and are left out of health insurance coverage are more likely to use traditional medicines. Second, cultural attitudes and ethnic group controls explain variation in utilisation, even among those who have health insurance. Results are suggestive of the validity of cultural interpretations

Single photo and electroproduction of pions at EBAC@JLAB

Within the Excited Baryon Analysis Center we have performed a dynamical coupled-channels analysis of the available $p(e,e' \pi)N$ data in the region of $W \leq$ 1.6 GeV and $Q^2 \leq$ 1.45 (GeV/c)$^2$. The channels included are $\gamma^* N$, $\pi N$, $\eta N$, and $\pi\pi N$ which has $\pi\Delta$, $\rho N$, and $\sigma N$ components. With the hadronic parameters of the model determined in our previous investigations of $\pi N\to \pi N$ reaction, we have found that the available data in the considered $W \leq$ 1.6 GeV region can be fitted well by only adjusting the bare $\gamma^* N \to N^*$ helicity amplitudes for the lowest $N^*$ states in $P_{33}$, $P_{11}$, $S_{11}$ and $D_{13}$ partial waves. The meson cloud effect, as required by the unitarity conditions, on the $\gamma^* N \to N^*$ form factors are examined.Comment: 6 pages, invited talk at NSTAR 2009, Beijing (China), 2009, to appear in the proceeding

Zero modes, energy gap, and edge states of anisotropic honeycomb lattice in a magnetic field

We present systematic study of zero modes and gaps by introducing effects of anisotropy of hopping integrals for a tight-binding model on the honeycomb lattice in a magnetic field. The condition for the existence of zero modes is analytically derived. From the condition, it is found that a tiny anisotropy for graphene is sufficient to open a gap around zero energy in a magnetic field. This gap behaves as a non-perturbative and exponential form as a function of the magnetic field. The non-analytic behavior with respect to the magnetic field can be understood as tunneling effects between energy levels around two Dirac zero modes appearing in the honeycomb lattice, and an explicit form of the gap around zero energy is obtained by the WKB method near the merging point of these Dirac zero modes. Effects of the anisotropy for the honeycomb lattices with boundaries are also studied. The condition for the existence of zero energy edge states in a magnetic field is analytically derived. On the basis of the condition, it is recognized that anisotropy of the hopping integrals induces abrupt changes of the number of zero energy edge states, which depend on the shapes of the edges sensitively.Comment: 36 pages, 20 figures; added discussion on experiments in Sec.VI, cited Refs.[35]-[40], and reworded Sec.IV

Laughlin states on the Poincare half-plane and its quantum group symmetry

We find the Laughlin states of the electrons on the Poincare half-plane in different representations. In each case we show that there exist a quantum group $su_q(2)$ symmetry such that the Laughlin states are a representation of it. We calculate the corresponding filling factor by using the plasma analogy of the FQHE.Comment: 9 pages,Late

Casimir invariants and characteristic identities for gl(∞)gl(\infty )

A full set of (higher order) Casimir invariants for the Lie algebra $gl(\infty )$ is constructed and shown to be well defined in the category $O_{FS}$ generated by the highest weight (unitarizable) irreducible representations with only a finite number of non-zero weight components. Moreover the eigenvalues of these Casimir invariants are determined explicitly in terms of the highest weight. Characteristic identities satisfied by certain (infinite) matrices with entries from $gl(\infty )$ are also determined and generalize those previously obtained for $gl(n)$ by Bracken and Green.$^{1,2}$Comment: 10 pages, PlainTe

Nodal Structure of Superconductors with Time-Reversal Invariance and Z2 Topological Number

A topological argument is presented for nodal structures of superconducting states with time-reversal invariance. A generic Hamiltonian which describes a quasiparticle in superconducting states with time-reversal invariance is derived, and it is shown that only line nodes are topologically stable in single-band descriptions of superconductivity. Using the time-reversal symmetry, we introduce a real structure and define topological numbers of line nodes. Stability of line nodes is ensured by conservation of the topological numbers. Line nodes in high-Tc materials, the polar state in p-wave paring and mixed singlet-triplet superconducting states are examined in detail.Comment: 11 pages, 8 figure