Detecting macroeconomic phases in the Dow Jones Industrial Average time series

In this paper, we perform statistical segmentation and clustering analysis of the Dow Jones Industrial Average (DJI) time series between January 1997 and August 2008. Modeling the index movements and log-index movements as stationary Gaussian processes, we find a total of 116 and 119 statistically stationary segments respectively. These can then be grouped into between five and seven clusters, each representing a different macroeconomic phase. The macroeconomic phases are distinguished primarily by their volatilities. We find that the US economy, as measured by the DJI, spends most of its time in a low-volatility phase and a high-volatility phase. The former can be roughly associated with economic expansion, while the latter contains the economic contraction phase in the standard economic cycle. Both phases are interrupted by a moderate-volatility market correction phase, but extremely-high-volatility market crashes are found mostly within the high-volatility phase. From the temporal distribution of various phases, we see a high-volatility phase from mid-1998 to mid-2003, and another starting mid-2007 (the current global financial crisis). Transitions from the low-volatility phase to the high-volatility phase are preceded by a series of precursor shocks, whereas the transition from the high-volatility phase to the low-volatility phase is preceded by a series of inverted shocks. The time scale for both types of transitions is about a year. We also identify the July 1997 Asian Financial Crisis to be the trigger for the mid-1998 transition, and an unnamed May 2006 market event related to corrections in the Chinese markets to be the trigger for the mid-2007 transition.     

The Hadwiger Number of Jordan Regions Is Unbounded

We show that for every n > 0 there is a planar topological disk A₀ and n translates A₁, A₂, ..., A_n of A₀ such that the interiors of A₀, ..., A_n are pairwise disjoint, but with each A_i touching A₀ for 1 ≤ i ≤ n.     

Analysis of an internal crack of pressure pipeline using ESPI and shearography

In this study, shearography and ESPI have been used for quantitative analysis of an internal crack of pipeline and both of them have proved to be suitable to qualitatively detect inside crack. However, shearography needs several critical? factors including the amount of shearing, shearing direction and induced load for the quantitative evaluation of the inside crack. In this study, the factors were optimized for the quantitative analysis and the size of cracks has been determined. Although the critical? factors in shearography have been optimized, it is difficult to determine the factors exactly because they are related to the details of cracks. On the other hand, ESPI is independent of the details of a crack and only the induced load plays an important role. The out-of-plane displacement was measured under the optimized load and the measured results were numerically differentiated, which resulted in an equivalent to the shearogram. The size of cracks can be determined quantitatively without any detail of a crack.     

Agglutination study of poly(allyl-alpha-D-glucopyranose/styrene) latex particles in the presence of Concanavalin A

Latex agglutination of the glucose-modified latex, which were synthesized by emulsion copolymerization of allyl-modified glucose and styrene monomers by specific binding interactions between Concanavalin A (Con A) and allyl-alpha-d-glucopyranose, were investigated. The surface of the glucose-modified latex was characterized by dye-partition method and the number of glucose was 1517 per latex particle. The average particle size and the polydispersity index of the latex were 78.3 and 1.005, respectively. Time-evolution adsorption behavior of various concentrations of the Con A and the consequent latex agglutination were studied by UV spectrophotometer at 540 nm and zeta-potential analyzer at the fixed latex concentration of 0.02 wt%. Specific binding between Con A and allyl-alpha-D-glucopyranose leaded the latex particles to coagulate by decreasing the electrostatic repulsion between the particles and mobility.     

Determination of ultrasonic wave velocities and phase velocity dispersion curves of an Inconel 600 plate using resonant ultrasound spectroscopy and leaky Lamb waves

A plate of Inconel 600 was interrogated using the resonant ultrasound spectroscopy (RUS) and the reflected leaky Lamb waves (LLW). It was found that the plate used in the present work has anisotropy in its material properties by the RUS. The longitudinal and the transverse wave velocities of the Inconel 600 plate were determined by the RUS, ultrasonic pulse-echo method and cut-off frequencies of the LLWs. The wave velocities in the direction of thickness determined by the RUS under the assumption of the orthotropic symmetry were quite similar to those obtained by other methods, the pulse-echo method and from cut-off frequencies. The reflected LLW from the plate was measured with varying the incident angle. The dispersion curves obtained from the reflected LLWs show good agreement with the theoretical calculation in general. The mismatches may be caused by anisotropy of the plate.     

Multiple-spot optical tweezers created with microlens arrays fabricated by proton beam writing

We report two different applications for using arrays of microlenses on glass substrate to facilitate multiple-spot optical trapping of colloidal microbeads. The array of microlenses was made of SU8 or PMMA resist and created by a combination of Proton-Beam writing followed by thermal reflow processes. Firstly, similar to previous reports [8, 9, 10 ], the lenses were utilized as an optical element in generating multiple laser spot arrays that were subsequently focused down to impose a microbead array. In addition, we demonstrated the feasibility of a novel approach of integrating the microlens array into a sample chamber to provide localized optical trapping. PACS 07.60.Pb; 41.75.Ak; 42.15.Eq; 42.65.Jx; 42.79.Bh     

Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4

The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr2O4, an excellent realization of the Heisenberg antiferromagnet on the pyrochlore network, a lattice distortion relieves the geometrical frustration through a spin-Peierls-like phase transition at T(c)=12.5 K. Conversely, spin correlations strongly influence the elastic properties of a frustrated magnet. By using infrared spectroscopy and published data on magnetic specific heat, we demonstrate that the frequency of an optical phonon triplet in ZnCr2O4 tracks the nearest-neighbor spin correlations above T(c). The splitting of the phonon triplet below T(c) provides a way to measure the spin-Peierls order parameter.     

Novel dielectric anomaly in the hole-doped La(2)Cu(1-x)Li(x)O(4) and La(2-x)Sr(x)NiO(4) insulators: signature of an electronic glassy state

The low-frequency dielectric response of hole-doped insulators La(2)Cu(1-x)Li(x)O(4) and La(2-x)Sr(x)NiO(4) shows a large dielectric constant epsilon(') at high temperature and a steplike drop by a factor of 100 at a material-dependent low temperature T(f). T(f) increases with frequency, and the dielectric response shows universal scaling in a Cole-Cole plot, suggesting that a charge-glass state is realized both in the cuprates and in the nickelates.     

Mössbauer studies of57Co-doped layered perovskites

Mössbauer spectra of⁵⁷Co-doped polycrystalline or single-crystal samples of layered perovskites La₂Mo₄ (M=Cu, Co, Ni) and R₂CuO₄ (R=Nd, Eu, Gd) were recorded at room temperature and below. Of the samples studied, only La₂CuO₄ shows a widely separated doublet at room temperature and a single clearly resolved sextet well belowT _N.     

Revealing the roles of Hamiltonian coupling in bound-state quantum systems

A Hamiltonian coupling identification (HCI) technique is introduced to reveal the independent and cooperative roles of Hamiltonian matrix elements in determining the bound-state energies of quantum systems. The HCI technique operates by encoding each Hamiltonian matrix element with a unique modulation signal, producing a nonlinear signature in the energy eigenvalues that may be decoded to reveal the contributing coupling structure in the Hamiltonian. The HCI technique is capable of exploring the roles of Hamiltonian coupling structure within and beyond the convergence limits of standard perturbation theory expansions. The flexibility residing in the encoding and decoding processes may be exploited to tailor the analysis to meet the desired degree of sought-after information about the Hamiltonian coupling structure. HCI, based on a Fourier encoding and decoding scheme, is illustrated by extracting information on the role of coupling interactions in the potential matrix elements of several simple model systems.