Ambiguity Aversion and Household Portfolio Choice Puzzles: Empirical Evidence

We test the relation between ambiguity aversion and five household portfolio choice puzzles: nonparticipation in equities, low allocations to equity, home-bias, own-company stock ownership, and portfolio under-diversification. In a representative US household survey, we measure ambiguity preferences using custom-designed questions based on Ellsberg urns. As theory predicts, ambiguity aversion is negatively associated with stock market participation, the fraction of financial assets in stocks, and foreign stock ownership, but it is positively related to own-company stock ownership. Conditional on stock ownership, ambiguity aversion is related to portfolio under-diversification, and during the financial crisis, ambiguity-averse respondents were more likely to sell stocks

International Conference VIDEO-ANALYSIS: METHODOLOGY AND METHODS

We test the relation between ambiguity aversion and five household portfolio choice puzzles: nonparticipation in equities, low allocations to equity, home-bias, own-company stock ownership, and portfolio under-diversification. In a representative US household survey, we measure ambiguity preferences using custom-designed questions based on Ellsberg urns. As theory predicts, ambiguity aversion is negatively associated with stock market participation, the fraction of financial assets in stocks, and foreign stock ownership, but it is positively related to own-company stock ownership. Conditional on stock ownership, ambiguity aversion is related to portfolio under-diversification, and during the financial crisis, ambiguity-averse respondents were more likely to sell stocks

Photonic realization of the relativistic Kronig-Penney model and relativistic Tamm surface states

Photonic analogues of the relativistic Kronig-Penney model and of relativistic surface Tamm states are proposed for light propagation in fibre Bragg gratings (FBGs) with phase defects. A periodic sequence of phase slips in the FBG realizes the relativistic Kronig-Penney model, the band structure of which being mapped into the spectral response of the FBG. For the semi-infinite FBG Tamm surface states can appear and can be visualized as narrow resonance peaks in the transmission spectrum of the grating

Why do naked singularities form in gravitational collapse?

We investigate what are the key physical features that cause the development of a naked singularity, rather than a black hole, as the end-state of spherical gravitational collapse. We show that sufficiently strong shearing effects near the singularity delay the formation of the apparent horizon. This exposes the singularity to an external observer, in contrast to a black hole, which is hidden behind an event horizon due to the early formation of an apparent horizon.Comment: revised for clarity, new figure included; version accepted by Phys. Rev. D (RC

Children living in the slums of Bangladesh face risks from unsafe food and water and stunted growth is common

Aim: This study investigated the microbial quality of food and water consumed by children in four slums in Dhaka, the capital of Bangladesh, together with the associated risk factors. Methods: This cross-sectional study took place from December 2015 to May 2016 and focused on 360 children under the age of five. We recorded household food security, namely adequate food for a healthy life, socio-economic and nutritional status, hygiene and feeding practices. Food and water samples were analysed. Results: We found that 63% of the children were malnourished and 58% were stunted. Yeast and moulds were detected in 86% of the food samples and coliforms in 73%. All the water samples were contaminated with faecal coliforms, yeasts and moulds and Staphylococcus. Food insecurity affected 83% of households. Children were twice as likely to be malnourished if they were born with a perceived low birth weight or their mothers did not wash their hands with soap after cleaning the child’s bottom following defecation. Exclusively breast-fed children were less likely to develop malnutrition. Conclusion: Children from the Dhaka slums were frequently stunted and malnourished and contaminated food and water was common. Integrated efforts are essential to create public awareness about hygiene

Fractional Quantum Hall Effect via Holography: Chern-Simons, Edge States, and Hierarchy

We present three holographic constructions of fractional quantum Hall effect (FQHE) via string theory. The first model studies edge states in FQHE using supersymmetric domain walls in N=6 Chern-Simons theory. We show that D4-branes wrapped on CP^1 or D8-branes wrapped on CP^3 create edge states that shift the rank or the level of the gauge group, respectively. These holographic edge states correctly reproduce the Hall conductivity. The second model presents a holographic dual to the pure U(N)_k (Yang-Mills-)Chern-Simons theory based on a D3-D7 system. Its holography is equivalent to the level-rank duality, which enables us to compute the Hall conductivity and the topological entanglement entropy. The third model introduces the first string theory embedding of hierarchical FQHEs, using IIA string on C^2/Z_n.Comment: 36 pages, 6 figures; v2: with an improved derivation of Hall conductivity in section 3.2, typo corrections, and additional references; v3: explanations and comments adde

Use of the Generalized Gradient Approximation in Pseudopotential Calculations of Solids

We present a study of the equilibrium properties of $sp$-bonded solids within the pseudopotential approach, employing recently proposed generalized gradient approximation (GGA) exchange correlation functionals. We analyze the effects of the gradient corrections on the behavior of the pseudopotentials and discuss possible approaches for constructing pseudopotentials self-consistently in the context of gradient corrected functionals. The calculated equilibrium properties of solids using the GGA functionals are compared to the ones obtained through the local density approximation (LDA) and to experimental data. A significant improvement over the LDA results is achieved with the use of the GGA functionals for cohesive energies. For the lattice constant, the same accuracy as in LDA can be obtained when the nonlinear coupling between core and valence electrons introduced by the exchange correlation functionals is properly taken into account. However, GGA functionals give bulk moduli that are too small compared to experiment.Comment: 15 pages, latex, no figure

Charged Higgs Boson Production in Bottom-Gluon Fusion

We compute the complete next-to-leading order SUSY-QCD corrections for the associated production of a charged Higgs boson with a top quark via bottom-gluon fusion. We investigate the applicability of the bottom parton description in detail. The higher order corrections can be split into real and virtual corrections for a general two Higgs doublet model and into additional massive supersymmetric loop contributions. We find that the perturbative behavior is well under control. The supersymmetric contributions consist of the universal bottom Yukawa coupling corrections and non-factorizable diagrams. Over most of the relevant supersymmetric parameter space the Yukawa coupling corrections are sizeable, while the remaining supersymmetric loop contributions are negligible.Comment: 18 pages, v2: some discussions added, v3: published versio

On the SUSY Accompanied Neutrino Exchange Mechanism of Neutrinoless Double Beta Decay

The neutrinoless double beta decay (\znbb) induced by light Majorana neutrino exchange between decaying nucleons, accompanied by the squark exchange inside one nucleon, recently discussed by Babu and Mohapatra, is carefully analyzed both from the particle and nuclear physics sides. New nuclear matrix elements relevant to this mechanism are calculated. We extend the analysis to include mixing of light neutrinos with heavy and "sterile" neutrinos. It introduces another supersymmetric (SUSY) contribution to \znbb. We discuss constraints on the \rp MSSM parameters imposed by the current experimental limit on \znbb decay half-life of $^{76}$Ge.Comment: LATEX, 10 pages + 2 (uuencoded) figures appende

From thermal rectifiers to thermoelectric devices

We discuss thermal rectification and thermoelectric energy conversion from the perspective of nonequilibrium statistical mechanics and dynamical systems theory. After preliminary considerations on the dynamical foundations of the phenomenological Fourier law in classical and quantum mechanics, we illustrate ways to control the phononic heat flow and design thermal diodes. Finally, we consider the coupled transport of heat and charge and discuss several general mechanisms for optimizing the figure of merit of thermoelectric efficiency.Comment: 42 pages, 22 figures, review paper, to appear in the Springer Lecture Notes in Physics volume "Thermal transport in low dimensions: from statistical physics to nanoscale heat transfer" (S. Lepri ed.