Tailored Raman-resonant four-wave-mixing processes

Nonlinear optical processes are strongly dominated by phase relationships among electromagnetic fields involved. In this paper, we theoretically and experimentally show that in a Raman-resonant four-wave-mixing process, the first anti-Stokes and Stokes generations can be tailored in a variety of ways by manipulating the phase relationships among the relevant electromagnetic fields

Flare Ribbons Observed with G-band and FeI 6302A Filters of the Solar Optical Telescope on Board Hinode

The Solar Optical Telescope (SOT) on board Hinode satellite observed an X3.4 class flare on 2006 December 13. Typical two-ribbon structure was observed, not only in the chromospheric CaII H line but also in G-band and FeI 6302A line. The high-resolution, seeing-free images achieved by SOT revealed, for the first time, the sub-arcsec fine structures of the "white light" flare. The G-band flare ribbons on sunspot umbrae showed a sharp leading edge followed by a diffuse inside, as well as previously known core-halo structure. The underlying structures such as umbral dots, penumbral filaments and granules were visible in the flare ribbons. Assuming that the sharp leading edge was directly heated by particle beam and the diffuse parts were heated by radiative back-warming, we estimate the depth of the diffuse flare emission using the intensity profile of the flare ribbon. We found that the depth of the diffuse emission is about 100 km or less from the height of the source of radiative back-warming. The flare ribbons were also visible in the Stokes-V images of FeI 6302A, as a transient polarity reversal. This is probably related to "magnetic transient" reported in the literature. The intensity increase in Stokes-I images indicates that the FeI 6302A line was significantly deformed by the flare, which may cause such a magnetic transient.Comment: 14 pages, 7 figures, PASJ in pres

A Systematic Examination of Particle Motion in a Collapsing Magnetic Trap Model for Solar Flares

Context. It has been suggested that collapsing magnetic traps may contribute to accelerating particles to high energies during solar flares. Aims. We present a detailed investigation of the energization processes of particles in collapsing magnetic traps, using a specific model. We also compare for the first time the energization processes in a symmetric and an asymmetric trap model. Methods. Particle orbits are calculated using guiding centre theory. We systematically investigate the dependence of the energization process on initial position, initial energy and initial pitch angle. Results. We find that in our symmetric trap model particles can gain up to about 50 times their initial energy, but that for most initial conditions the energy gain is more moderate. Particles with an initial position in the weak field region of the collapsing trap and with pitch angles around 90 degrees achieve the highest energy gain, with betatron acceleration of the perpendicular energy the dominant energization mechanism. For particles with smaller initial pitch angle, but still outside the loss cone, we find the possibility of a significant increase in parallel energy. This increase in parallel energy can be attributed to the curvature term in the parallel equation of motion and the associated energy gain happens in the center of the trap where the field line curvature has its maximum. We find qualitatively similar results for the asymmetric trap model, but with smaller energy gains and a larger number of particles escaping from the trap.Comment: 11 pages, 13 figures. To be published in Astronomy and Astrophysic

New Computer-Aided Diagnosis of Dementia Using Positron Emission Tomography: Brain Regional Sensitivity-Mapping Method

Purpose: We devised a new computer-aided diagnosis method to segregate dementia using one estimated index (Total Z score) derived from the Brodmann area (BA) sensitivity map on the stereotaxic brain atlas. The purpose of this study is to investigate its accuracy to differentiate patients with Alzheimer’s disease (AD) or mild cognitive impairment (MCI) from normal adults (NL). Methods: We studied 101 adults (NL: 40, AD: 37, MCI: 24) who underwent 18FDG positron emission tomography (PET) measurement. We divided NL and AD groups into two categories: a training group with (Category A) and a test group without (Category B) clinical information. In Category A, we estimated sensitivity by comparing the standard uptake value per BA (SUVR) between NL and AD groups. Then, we calculated a summated index (Total Z score) by utilizing the sensitivitydistribution maps and each BA z-score to segregate AD patterns. To confirm the validity of this method, we examined the accuracy in Category B. Finally, we applied this method to MCI patients. Results: In Category A, we found that the sensitivity and specificity of differentiation between NL and AD were all 100%. In Category B, those were 100% and 95%, respectively. Furthermore, we found this method attained 88% to differentiate ADconverters from non-converters in MCI group. Conclusions: The present automated computer-aided evaluation method based on a single estimated index provided good accuracy for differential diagnosis of AD and MCI. This good differentiation power suggests its usefulness not only for dementia diagnosis but also in a longitudinal study.浜松医科大学学位論文　医博第695号（平成27年3月16日

Benefits of Artificially Generated Gravity Gradients for Interferometric Gravitational-Wave Detectors

We present an approach to experimentally evaluate gravity gradient noise, a potentially limiting noise source in advanced interferometric gravitational wave (GW) detectors. In addition, the method can be used to provide sub-percent calibration in phase and amplitude of modern interferometric GW detectors. Knowledge of calibration to such certainties shall enhance the scientific output of the instruments in case of an eventual detection of GWs. The method relies on a rotating symmetrical two-body mass, a Dynamic gravity Field Generator (DFG). The placement of the DFG in the proximity of one of the interferometer's suspended test masses generates a change in the local gravitational field detectable with current interferometric GW detectors.Comment: 16 pages, 4 figure

Human Rehearsal Processes and the Frontal Lobes: PET Evidence

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71395/1/j.1749-6632.1995.tb38134.x.pd

Statistics of low-energy levels of a one-dimensional weakly localized Frenkel exciton: A numerical study

Numerical study of the one-dimensional Frenkel Hamiltonian with on-site randomness is carried out. We focus on the statistics of the energy levels near the lower exciton band edge, i. e. those determining optical response. We found that the distribution of the energy spacing between the states that are well localized at the same segment is characterized by non-zero mean, i.e. these states undergo repulsion. This repulsion results in a local discrete energy structure of a localized Frenkel exciton. On the contrary, the energy spacing distribution for weakly overlapping local ground states (the states with no nodes within their localization segments) that are localized at different segments has zero mean and shows almost no repulsion. The typical width of the latter distribution is of the same order as the typical spacing in the local discrete energy structure, so that this local structure is hidden; it does not reveal itself neither in the density of states nor in the linear absorption spectra. However, this structure affects the two-exciton transitions involving the states of the same segment and can be observed by the pump-probe spectroscopy. We analyze also the disorder degree scaling of the first and second momenta of the distributions.Comment: 10 pages, 6 figure

Arterial/venous plasma nicotine concentrations following nicotine nasal spray

Background and objectives : Arterial (A) and venous (V) plasma nicotine and cotinine concentrations were measured after nasal nicotine spray in tobacco smokers of both genders. The hypothesis for this research was that a greater A/V difference in plasma nicotine would be present in males than females because males have greater skeletal muscle mass to bind nicotine.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42031/1/228-55-9-639_90550639.pd

The Significance of Family History Status in Relation to Neuropsychological Test Performance and Cerebral Glucose Metabolism Studied with Positron Emission Tomography in Older Alcoholic Patients

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66033/1/j.1530-0277.1998.tb03622.x.pd