Psychological Costs of Migration: Home Country Natural Disasters and Mental Health

The psychological toll of leaving one's familiar environment is a dominant explanation for why some people do not migrate despite relatively high wage differentials and low monetary costs of moving. Yet there is little direct empirical evidence on the existence and the characteristics of psychic costs. Using linked administrative and survey data (the 45 and Up Study) from Australia, a country where one in four residents was born overseas, we show that migrant mental health is significantly affected by home country natural disasters. In the three months following a disaster, mental health related drug use and visits to mental health specialists increase by 5% and 33%, respectively. The effects persist for up to 12 months after the initial shock and increase with distance to the home country. In contrast, we do not find any effects of home country disasters on the physical health conditions of migrants. Given that individuals in our sample have lived in their destination country for an average of 40 years, our estimates suggest strong persistence in these costs

Acoustic modes in fluid networks

Pressure and flow rate eigenvalue problems for one-dimensional flow of a fluid in a network of pipes are derived from the familiar transmission line equations. These equations are linearized by assuming small velocity and pressure oscillations about mean flow conditions. It is shown that the flow rate eigenvalues are the same as the pressure eigenvalues and the relationship between line pressure modes and flow rate modes is established. A volume at the end of each branch is employed which allows any combination of boundary conditions, from open to closed, to be used. The Jacobi iterative method is used to compute undamped natural frequencies and associated pressure/flow modes. Several numerical examples are presented which include acoustic modes for the Helium Supply System of the Space Shuttle Orbiter Main Propulsion System. It should be noted that the method presented herein can be applied to any one-dimensional acoustic system involving an arbitrary number of branches

Total ozone changes in the 1987 Antarctic ozone hole

The development of the Antarctic ozone minimum was observed in 1987 with the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) instrument. In the first half of August the near-polar (60 and 70 deg S) ozone levels were similar to those of recent years. By September, however, the ozone at 70 and 80 deg S was clearly lower than any previous year including 1985, the prior record low year. The levels continued to decrease throughout September until October 5 when a new record low of 109 DU was established at a point near the South Pole. This value is 29 DU less than the lowest observed in 1985 and 48 DU less than the 1986 low. The zonal mean total ozone at 60 deg S remained constant throughout the time of ozone hole formation. The ozone decline was punctuated by local minima formed away from the polar night boundary at about 75 deg S. The first of these, on August 15 to 17, formed just east of the Palmer Peninsula and appears to be a mountain wave. The second major minimum formed on September 5 to 7 again downwind of the Palmer Peninsula. This event was larger in scale than the August minimum and initiated the decline of ozone across the polar region. The 1987 ozone hole was nearly circular and pole centered for its entire life. In previous years the hole was perturbed by intrusions of the circumpolar maximum into the polar regions, thus causing the hole to be elliptical. The 1987 hole also remained in place until the end of November, a few days longer than in 1985, and this persistence resulted in the latest time for recovery to normal values yet observed

Electrical transport through a single-electron transistor strongly coupled to an oscillator

We investigate electrical transport through a single-electron transistor coupled to a nanomechanical oscillator. Using a combination of a master-equation approach and a numerical Monte Carlo method, we calculate the average current and the current noise in the strong-coupling regime, studying deviations from previously derived analytic results valid in the limit of weak-coupling. After generalizing the weak-coupling theory to enable the calculation of higher cumulants of the current, we use our numerical approach to study how the third cumulant is affected in the strong-coupling regime. In this case, we find an interesting crossover between a weak-coupling transport regime where the third cumulant heavily depends on the frequency of the oscillator to one where it becomes practically independent of this parameter. Finally, we study the spectrum of the transport noise and show that the two peaks found in the weak-coupling limit merge on increasing the coupling strength. Our calculation of the frequency-dependence of the noise also allows to describe how transport-induced damping of the mechanical oscillations is affected in the strong-coupling regime.Comment: 11 pages, 9 figure

Onset of a boson mode at superconducting critical point of underdoped YBa2Cu3Oy

The thermal conductivity $\kappa$ of underdoped \Y was measured in the $T \to 0$ limit as a function of hole concentration $p$ across the superconducting critical point at $p_{SC}$ = 5.0%. ``Time doping'' was used to resolve the evolution of bosonic and fermionic contributions with high accuracy. For $p \leqslant p_{SC}$, we observe an additional $T^3$ contribution to $\kappa$ which we attribute to the boson excitations of a phase with long-range spin or charge order. Fermionic transport, manifest as a linear term in $\kappa$, is seen to persist unaltered through $p_{SC}$, showing that the state just below $p_{SC}$ is a thermal metal. In this state, the electrical resistivity varies as log$(1/T)$ and the Wiedemann-Franz law is violated

Does self-assessed health measure health?

Despite concerns about reporting biases and interpretation, self-assessed health (SAH) remains the measure of health most used by researchers, in part reflecting its ease of collection and in part the observed correlation between SAH and objective measures of health. Using a unique Australian data set, which consists of survey data linked to administrative individual medical records, we present empirical evidence demonstrating that SAH indeed predicts future health, as measured by hospitalizations, out-of-hospital medical services and prescription drugs. Our large sample size allows very disaggregate analysis and we find that SAH predicts more serious, chronic illnesses better than less serious illnesses. Finally, we compare the predictive power of SAH relative to administrative data and an extensive set of self-reported health measures; SAH does not add to the predictive power of future utilization when the administrative data is included and improves prediction only marginally when the extensive survey-based health measures are included. Clearly there is value in the more extensive survey and administrative health data as well as greater cost of collection

Analysis of Fluid Gauge Sensor for Zero or Microgravity Conditions using Finite Element Method

In this paper the Finite Element Method (FEM) is presented for mass/volume gauging of a fluid in a tank subjected to zero or microgravity conditions. In this approach first mutual capacitances between electrodes embedded inside the tank are measured. Assuming the medium properties the mutual capacitances are also estimated using FEM approach. Using proper non-linear optimization the assumed properties are updated by minimizing the mean square error between estimated and measured capacitances values. Numerical results are presented to validate the present approach

Thermal Conductivity of the Iron-Based Superconductor FeSe : Nodeless Gap with Strong Two-Band Character

The thermal conductivity of the iron-based superconductor FeSe was measured at temperatures down to 50 mK in magnetic fields up to 17 T. In zero magnetic field, the electronic residual linear term in the T = 0 limit, \kappa_0/T, is vanishingly small. Application of a magnetic field H causes no increase in \kappa_0/T initially. Those two observations show that there are no zero-energy quasiparticles that carry heat and therefore no nodes in the superconducting gap of FeSe. The full field dependence of \kappa_0/T has the classic shape of a two-band superconductor, such as MgB2: it rises exponentially at very low field, with a characteristic field H* << Hc2, and then more slowly up to the upper critical field Hc2. This shows that the superconducting gap is very small on one of the pockets in the Fermi surface of FeSe

Dynamical matrix of two-dimensional electron crystals

In a quantizing magnetic field, the two-dimensional electron (2DEG) gas has a rich phase diagram with broken translational symmetry phases such as Wigner, bubble, and stripe crystals. In this paper, we derive a method to get the dynamical matrix of these crystals from a calculation of the density response function performed in the Generalized Random Phase Approximation (GRPA). We discuss the validity of our method by comparing the dynamical matrix calculated from the GRPA with that obtained from standard elasticity theory with the elastic coefficients obtained from a calculation of the deformation energy of the crystal.Comment: Revised version published in Phys. Rev. B. 12 pages with 11 postscripts figure

Anisotropic states of two-dimensional electrons in high magnetic fields

We study the collective states formed by two-dimensional electrons in Landau levels of index $n\ge 2$ near half-filling. By numerically solving the self-consistent Hartree-Fock (HF) equations for a set of oblique two-dimensional lattices, we find that the stripe state is an anisotropic Wigner crystal (AWC), and determine its precise structure for varying values of the filling factor. Calculating the elastic energy, we find that the shear modulus of the AWC is small but finite (nonzero) within the HF approximation. This implies, in particular, that the long-wavelength magnetophonon mode in the stripe state vanishes like $q^{3/2}$ as in an ordinary Wigner crystal, and not like $q^{5/2}$ as was found in previous studies where the energy of shear deformations was neglected.Comment: minor corrections; 5 pages, 4 figures; version to be published in Physical Review Letter