Detecting Baryon Acoustic Oscillations in Dark Matter from Kinematic Weak Lensing Surveys

We investigate the feasibility of extracting Baryon Acoustic Oscillations (BAO) from cosmic shear tomography. We particularly focus on the BAO scale precision that can be achieved by future spectroscopy-based, kinematic weak lensing (KWL) surveys \citep[e.g.,][]{Huff13} in comparison to the traditional photometry-based weak lensing surveys. We simulate cosmic shear tomography data of such surveys with a few simple assumptions to focus on the BAO information, extract the spacial power spectrum, and constrain the recovered BAO feature. Due to the small shape noise and the shape of the lensing kernel, we find that a Dark Energy Task Force Stage IV version of such KWL survey can detect the BAO feature in dark matter by $3$-$\sigma$ and measure the BAO scale at the precision level of 4\% while it will be difficult to detect the feature in photometry-based weak lensing surveys. With a more optimistic assumption, a KWL-Stage IV could achieve a $\sim 2\%$ BAO scale measurement with $4.9$-$\sigma$ confidence. A built-in spectroscopic galaxy survey within such KWL survey will allow cross-correlation between galaxies and cosmic shear, which will tighten the constraint beyond the lower limit we present in this paper and therefore possibly allow a detection of the BAO scale bias between galaxies and dark matter.Comment: 18 pages, 10 figures; revised arguments in section 2, results unchange

Effects of Environment on Depressive Symptoms on Chinese Left-Behind Children

Estimates indicate that about 70 million children in China have been left behind in their hometowns by one or both parents as their parents migrate to other places for work opportunities. However, the potential impact of parental migration on the emotional well-being of left-behind children is still unclear. The purpose of this study was to examine depression levels in Chinese left-behind children and to identify potential risk factors contributing to depressive symptoms in this population. Using a nationally-representative, stratified sample from the China Family Panel Studies (CFPS) database (3019 children, ages 10-15), an HLM model was applied at 1) the child level measuring the influence of family structure and individual-level parenting practices, and 2) the county level estimating the effects of rural vs. urban differences and county-level parenting practices. Cross-level effects between child factors and county factors were also examined. The depressive symptoms were measured by the Center for Epidemiologic Studies Depression (CES-D, Radloff, 1977). Findings indicated that the left-behind children were more likely to report higher scores on depressive symptoms indices than children from intact families. Children reporting more positive parenting practices also tended to have fewer depressive symptoms. The effect of family structures on children’s depressive symptoms depended on the county-level parental behaviors. Implications for schools and parenting practices were discussed

Comparison of Image Registration Based Measures of Regional Lung Ventilation from Dynamic Spiral CT with Xe-CT

Purpose: Regional lung volume change as a function of lung inflation serves as an index of parenchymal and airway status as well as an index of regional ventilation and can be used to detect pathologic changes over time. In this article, we propose a new regional measure of lung mechanics --- the specific air volume change by corrected Jacobian. Methods: 4DCT and Xe-CT data sets from four adult sheep are used in this study. Nonlinear, 3D image registration is applied to register an image acquired near end inspiration to an image acquired near end expiration. Approximately 200 annotated anatomical points are used as landmarks to evaluate registration accuracy. Three different registration-based measures of regional lung mechanics are derived and compared: the specific air volume change calculated from the Jacobian (SAJ); the specific air volume change calculated by the corrected Jacobian (SACJ); and the specific air volume change by intensity change (SAI). Results: After registration, the mean registration error is on the order of 1 mm. For cubical ROIs in cubes with size 20 mm $\times$ 20 mm $\times$ 20 mm, the SAJ and SACJ measures show significantly higher correlation (linear regression, average $r^2=0.75$ and $r^2=0.82$) with the Xe-CT based measure of specific ventilation (sV) than the SAI measure. For ROIs in slabs along the ventral-dorsal vertical direction with size of 150 mm $\times$ 8 mm $\times$ 40 mm, the SAJ, SACJ, and SAI all show high correlation (linear regression, average $r^2=0.88$, $r^2=0.92$ and $r^2=0.87$) with the Xe-CT based sV without significant differences when comparing between the three methods. Conclusion: Given a deformation field by an image registration algorithm, significant differences between the SAJ, SACJ, and SAI measures were found at a regional level compared to the Xe-CT sV in four sheep that were studied

University English Teachers’ Professional Development Through Academic Visits: Using Identity as a Theoretical Lens

Academic visitor programs aim to enhance university teachers’ teaching and research capacity and intercultural competence. Its impact, however, has remained under-researched. Using the data collected from two rounds of in-depth interviews with 13 Chinese university English teachers over a year and a half, this study explored their experiences as academic visitors in the UK through the lens of professional identity. Findings revealed that the participants came with various expectations and negotiated and constructed different identities during their academic visits. The participants’ developing identities in turn affected their investment in their professional development in their situated contexts. The study provides important implications for academic visit programs which need to be designed in line with the complex needs and identities of university teachers

Invertibility of Multi-Energy X-ray Transform

Purpose: The goal is to provide a sufficient condition on the invertibility of a multi-energy (ME) X-ray transform. The energy-dependent X-ray attenuation profiles can be represented by a set of coefficients using the Alvarez-Macovski (AM) method. An ME X-ray transform is a mapping from $N$ AM coefficients to $N$ noise-free energy-weighted measurements, where $N\geq2$. Methods: We apply a general invertibility theorem which tests whether the Jacobian of the mapping $J(\mathbf A)$ has zero values over the support of the mapping. The Jacobian of an arbitrary ME X-ray transform is an integration over all spectral measurements. A sufficient condition of $J(\mathbf A)\neq0$ for all $\mathbf A$ is that the integrand of $J(\mathbf A)$ is $\geq0$ (or $\leq0$) everywhere. Note that the trivial case of the integrand equals to zero everywhere is ignored. With symmetry, we simplified the integrand of the Jacobian into three factors that are determined by the total attenuation, the basis functions, and the energy-weighting functions, respectively. The factor related to total attenuation is always positive, hence the invertibility of the X-ray transform can be determined by testing the signs of the other two factors. Furthermore, we use the Cramer-Rao lower bound (CRLB) to characterize the noise-induced estimation uncertainty and provide a maximum-likelihood (ML) estimator. Conclusions: We have provided a framework to study the invertibility of an arbitrary ME X-ray transform and proved the global invertibility for four types of systems

South Sudan: The Birth of an Economy

We discuss the birth of a new economy in a society that has only recently emerged from a 22-year-long civil war. The pace of growth so far has been fast but uneven. We find that aid and oil money are flowing rapidly into certain sectors, while other employment-generating areas of the economy, particularly agriculture, have barely changed their centuries-old ways. As a result, the recent windfall of wealth has yet to translate into tangible development benefits for the majority of the population. In order to achieve growth in these other sectors, there is a need for more innovation in both government policy and business strategy

On Finding an Equivalent Force to Mimic the Multilayer Ceramic Capacitor Vibration

The Multilayer Ceramic Capacitor (MLCC) Can Vibrate Due to the Piezoelectric Effect When There is AC Noise on the Power Rail. the Vibration of the Capacitor Will Generate a Force on the PCB and Thus Cause the PCB Vibration and Audible Problems May Occur. the Work in This Paper Finds an Equivalent Force with Similar Behavior to the MLCC-Generated Force. the Force is Controllable and Knowable and Thus Can Mimic the Capacitor Vibration on the PCB

Simulated Dynamical Weakening and Abelian Avalanches in Mean-Field Driven Threshold Models

Mean-field coupled lattice maps are used to approximate the physics of driven threshold systems with long range interactions. However, they are incapable of modeling specific features of the dynamic instability responsible for generating avalanches. Here we present a method of simulating specific frictional weakening effects in a mean field slider block model. This provides a means of exploring dynamical effects previously inaccessible to discrete time simulations. This formulation also results in Abelian avalanches, where rupture propagation is independent of the failure sequence. The resulting event size distribution is shown to be generated by the boundary crossings of a stochastic process. This is applied to typical models to explain some commonly observed features.Comment: 27 pages, 9 figure