192 research outputs found
The Importance Of Housing Variables In Predicting Economic Fluctuations
This paper investigates the importance of housing variables in predicting the six recent recessions using factor analysis model. It shows that housing variables have great predictive power in forecasting the downturn of the economy, but little predictive power when the economy is steady or is expanding. The explanation is that housing variables match consumers\u27 expectations of future income and employment, and consequently predict future economic downturn. By using Granger-Causality test and vector autoregression (VAR) model, combination of factor analysis and VAR model, and hard thresholding method to identify the importance of each housing variable, the results show that housing price indexes are not important in forecasting the economy, but that measures of housing volumes improve predictions. Moreover, the housing volume measures with one-unit of structure tends to play a greater role in the prediction
Efficient generation of many-body singlet states of spin-1 bosons in optical superlattices
We propose an efficient stepwise adiabatic merging (SAM) method to generate
many-body singlet states in antiferromagnetic spin-1 bosons in concatenated
optical superlattices with isolated double-well arrays, by adiabatically
ramping up the double-well bias. With an appropriate choice of bias sweeping
rate and magnetic field, the SAM protocol predicts a fidelity as high as 90%
for a sixteen-body singlet state and even higher fidelities for smaller
even-body singlet states. During their evolution, the spin-1 bosons exhibit
interesting squeezing dynamics, manifested by an odd-even oscillation of the
experimentally observable squeezing parameter. The generated many-body singlet
states may find practical applications in precision measurement of magnetic
field gradient and in quantum information processing.Comment: 8 pages, 8 figures, submitted to Phys. Rev.
Superconducting Properties of Graphene Doped Magnesium Diboride
Graphene, carbon in the form of monolayer sheets, has revealed astonishing and unique chemical and physical properties, which have made it an extremely active research topic in both materials science and physics (Novoselov, K. S. et al., 2004). Through chemical and materials integration, graphene is being actively exploited in a range of technological applications (Stankovich, S. et al., 2006). Superconductors can carry electrical current without any energy dissipation. The combination of both graphene and a superconductor into a composite has great potential for electrical devices and large scale applications. MgB2, a superconductor with a simple composition and two-gap feature has great potential for large current carrying applications, as demonstrated through a series of chemical dopings (Dou, S. X. et al. 2007). In the case of graphene’s, the strict two-dimensionality and its high electrical and thermal conductivities, make it an ideal candidate for integrating/doping into MgB2 in order to improve the superconducting properties
Effective size of a trapped atomic Bose gas
We investigate the temperature-dependent effective size of a trapped
interacting atomic Bose gas within a mean field theory approximation. The
sudden shrinking of the average length, as observed in an earlier experiment by
Wang {\it et al.} [Chin. Phys. Lett. {\bf 20}, 799 (2003)], is shown to be a
good indication for Bose-Einstein condensation (BEC). Our study also supports
the use of the average width of a trapped Bose gas for a nondestructive
calibration of its temperature.Comment: RevTex4, 6 pages, 4 eps figures, to appear in Phys. Rev.
Enhanced measurement precision with continuous interrogation during dynamical decoupling
Dynamical decoupling (DD) is normally ineffective when applied to DC
measurement. In its straightforward implementation, DD nulls out DC signal as
well while suppressing noise. This work proposes a phase relay method (PRM)
that is capable of continuously interrogating the DC signal over many DD
cycles. We illustrate its efficacy when applied to measurement of a weak DC
magnetic field with an atomic spinor Bose-Einstein condensate. Sensitivities
approaching standard quantum limit (SQL) or Heisenberg limit (HL) are
potentially realizable for a coherent spin state (CSS) or a squeezed spin state
(SSS) of 10,000 atoms respectively, while ambient laboratory level noise is
suppressed by DD. Our work offers a practical approach to mitigate the
limitations of DD to DC measurement and will like find other applications for
resorting coherence in quantum sensing and quantum information processing
research
Differential responses to genotoxic agents between induced pluripotent stem cells and tumor cell lines
Given potential values of induced pluripotent stem (iPS) cells in basic biomedical research and regenerative medicine, it is important to understand how these cells regulate their genome stability in response to environmental toxins and carcinogens. The present study characterized the effect of Cr(VI), a well-known genotoxic agent and environmental carcinogen, on major molecular components of DNA damage response pathways in human iPS cells. We compared the effect of Cr(VI) on human iPS cells with two established cell lines, Tera-1 (teratoma origin) and BEAS-2B (lung epithelial origin). We also studied the effect of hydrogen peroxide and doxorubicin on modulating DNA damage responses in these cell types. We demonstrated that ATM and p53 phosphorylation is differentially regulated in human iPS cells compared with Tera-1 and BEAS-2B cells after exposure to various genotoxic agents. Moreover, we observed that inhibition of CK2, but not p38, promotes phosphorylation of p53(S392) in iPS cells. Combined, our data reveal some unique features of DNA damage responses in human iPS cells
catena-Poly[[[diaquairon(II)]-μ-pyrazine-2,3-dicarboxylato] dihydrate]
The crystal structure of the title compound, {[Fe(C6H2N2O4)(H2O)2]·2H2O}n, was synthesized by a diffusion method. It has a one-dimensional polymeric chain structure and the chains are further connected into a three-dimensional structure by hydrogen bonds. The FeII ion has a distorted octahedral coordination environment, with two N and two O atoms from the pyrazine-2,3-dicarboxylate ligands in the equatorial plane and with two water molecules in axial positions. The Fe atom lies on a crystallographic centre of symmetry and a twofold rotation axis passes through the pyrazine ring
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