Rapid acquisition strategy for functional T1ρ mapping of the brain

Functional T1ρ mapping has been proposed as a method to assess pH and metabolism dynamics in the brain with high spatial and temporal resolution. The purpose of this work is to describe and evaluate a variant of the spin-locked echo-planar imaging sequence for functional T1ρ mapping at 3 T. The proposed sequence rapidly acquires a time series of T1ρ maps with 4.0 second temporal resolution and 10 slices of volumetric coverage. Simulation, phantom, and in vivo experiments are used to evaluate many aspects of the sequence and its implementation including fidelity of measured T1ρ dynamics, potential confounds to the T1ρ response, imaging parameter tradeoffs, time series analysis approaches, and differences compared to blood oxygen level dependent functional magnetic resonance imaging. It is shown that the high temporal resolution and volumetric coverage of the sequence are obtained with some expense including underestimation of the T1ρ response, sensitivity to T1 dynamics, and reduced signal-to-noise ratio. In vivo studies using a flashing checkerboard functional magnetic resonance imaging paradigm suggest differences between T1ρ and blood oxygen level dependent activation patterns. Possible sources of the functional T1ρ response and potential sequence improvements are discussed. The capability of T1ρ to map whole-brain pH and metabolism dynamics with high temporal and spatial resolution is potentially unique and warrants further investigation and development.     

Conformation‐Specific Circular Dichroism Spectroscopy of Cold,Isolated Chiral Molecules

The CD spectroscopy of a chiral compound in solution yields an average CD value derived from all of the conformations of a chiral molecule. By contrast, CD spectroscopy of cold chiral molecules in the gas phase distinguishes specific conformers of a chiral molecule, but the weak CD effect has limited the practical application of this technique. Reported herein is the first resonant two‐photon ionization CD spectra of ephedrines in a supersonic jet using circularly polarized laser pulses, which were generated by synchronizing the oscillation of the photoelastic modulator with the laser firing. The spectra exhibited well‐resolved CD bands which were specific for the conformations and vibrational modes of each enantiomer. The CD signs and magnitudes of the jet‐cooled chiral molecules were very sensitive to their conformations and thus offered crucial information for determining the three‐dimensional structures of chiral species, as conducted in combination with quantum chemical calculations.     

Simultaneous control of haze and transmittance using a dye-doped cholesteric liquid crystal cell

We propose a light shutter device using dye-doped cholesteric liquid crystals for a high-visibility see-through display. In the focal-conic state, the proposed device can perfectly block the background image through simultaneous use of light scattering and absorption effects in a single-layered structure. By switching the proposed device placed at the backside of a see-through display, we can choose transparent or high-visibility display modes in a see-through display.     

Optimal three-level presort loading of commercial bulk mail in the postal service industry

This study focuses on the presort loading of commercial bulk mail. Here, presort is the process by which a mailer prepares mail such that it is sorted to at least the finest extent required by the postal service provider for a claimed (discounted) price. We formulated this presort loading problem (PLP) as a special case of transportation problem with minimum quantity commitment (MQC) constraints. In addition, we developed a polynomial time optimal solution algorithm for the PLP and performed computational experiments on randomly generated problem instances under various discount structures. Results of the computational experiments show that mailers can potentially reduce their costs by sending mail less frequently, using small-sized mail trays; however, the discount structure does not affect the main results. There is some evidence that smaller cost reductions on mailing fees occur as the variation in the discount rate increases; however, the effects of discount structure are nominal compared with the gains from changing the mailing frequency. Mailing fee savings are more heavily influenced by the discount structure when MQC constraints become tighter.     

A study on the characterization and stability of rhenium(III) chloride-incorporated liposomes

Nanoliposomes are important carriers capable of packaging drugs for various delivery applications through passive targeting tumor sites by enhancing permeability and retention effect. Radiolabeled liposomes have potential applications in radiotherapy and diagnostic imaging. However, the physico-chemical instability of liposomes during manufacturing and storage limits their extensive application. Therefore, considerable numbers of studies have been made on the stability of liposomes over the last few years in order to overcome this problem. In this study, we attempted to prepare polymer-coated liposomes using water-soluble chitosan in order to enhance the stability of rhenium(III) chloride-incorporated liposomes. They were characterized by an electrophoretic light-scattering spectrophotometer, Fourier transform infrared spectroscopy (FT-IR), UV–Vis spectrometer, and phase-contrast microscopy. The chitosan-coated liposomes are spherical and the particle size is about 800–850 nm. Incorporation of chitosan into the liposome bilayer decreased rhenium(III) chloride release from the liposome due to an increased rigidity of the liposome membrane structure. Chitosan-coated liposomes showed a higher stability compared with the stability of non-coated liposomes. The release characteristics of rhenium(III) chloride encapsulated in the liposome were taken as a measure of stability of the liposome membrane.     

Evaluation of tailored magnetic composite films for near-field electromagnetic noise suppression

The effects of permeability and permittivity of the magnetic nanorods filled in composite films have been studied in the broadband radio-frequency range from 0.5 to 10 GHz on a microstrip line. The transmission power absorption of the composite film on a microstrip line was simulated using 3D FEM HFSS program. The model of microstrip line was designed based on IEC standard (IEC 62333-2). The permeability of composite film with magnetic nanorods could be controlled by the aspect ratio of nanorods. The ferromagnetic resonance frequency and the relative complex permeability with the change of aspect ratio were calculated by the Landau–Lifshitz–Gilbert equation. Given the bulk magnetization of 5 kG, the power loss frequency region has exhibited the 2.5–7 GHz broadband frequency by mixing of nanorods with various aspect ratios from 2 to 10. The permittivity effects have been evaluated by changing the real part of permittivity with a fixed imaginary part value and vice versa. The power losses were increased with the proportional to the imaginary part of permittivity and did not show any significant change with the increment of the real part of permittivity. The conduction electromagnetic noise in near field can be suppressed by controlling complex permeability with various aspect ratios of the magnetic nanorods in the composite.

     

Minimal Dirac fermionic dark matter with nonzero magnetic dipole moment

A neutral Dirac fermion ψ   with a nonzero magnetic dipole moment is supplied as a singlet within the context of the standard model and is considered as a dark matter candidate near the electroweak scale (10–1000 GeV$10\text{–}1000\text{GeV}$). We discuss its dynamics with the ordinary matters through the magnetic dipole moment. The magnetic dipole moment constrained by the relic abundance may be as large as ¹⁰⁻¹⁸–¹⁰⁻¹⁷e⋅cm${10}^{-18}\text{–}{10}^{-17}e\cdot \text{cm}$. We show that the elastic scattering is due to a spin–spin interaction for the direct detections and the predictions are under experimental exclusion limits of the current direct detectors, XENON10 and CDMS II, and consider the possibility of dark matter detection in the future.     

Exploring uses of persistent homology for statistical analysis of landmark-based shape data

A method for the use of persistent homology in the statistical analysis of landmark-based shape data is given. Three-dimensional landmark configurations are used as input for separate filtrations, persistent homology is performed, and persistence diagrams are obtained. Groups of configurations are compared using distances between persistence diagrams combined with dimensionality reduction methods. A three-dimensional landmark-based data set is used from a longitudinal orthodontic study, and the persistent homology method is able to distinguish clinically relevant treatment effects. Comparisons are made with the traditional landmark-based statistical shape analysis methods of Dryden and Mardia, and Euclidean Distance Matrix Analysis.     

The role of sample collection method and the bias between different standard matrices in the determination of volatile organic compounds in air

This study was undertaken to assess the relative bias between two types of sampling methods for volatile organic compounds (VOCs), i.e., sorbent tube vs. bag sampling methods and between different standard phases. For the purpose of this comparative study, gaseous standards containing three major aromatic VOCs (benzene, toluene, and xylene—commonly called BTX) were analyzed by thermo-desorption gas chromatography (TD-GC) with flame ionization detector. According to our findings, the relative response of target compounds can be smaller in the bag method than in the tube method. Although the relative bias varies with the sample transfer conditions for the TD, the mean slope values of the former are smaller by up to 20% relative to the latter, possibly due to sorptive loss on the bag sampler. In addition, the effects of different standard matrices (i.e. liquid and gas phases) were also examined using the sorbent tube method. The results indicated that the slope values of the gas-phase standard were smaller by half (about 43–56%) than the liquid-phase standard. Consequently, information concerning the extent of relative bias between sampling methods (e.g., bag and tube) or standard matrices (e.g., gas and liquid) should be considered as one of the key factors in TD applications.