Characteristics of train noise in above-ground and underground stations with side and island platforms

Railway stations can be principally classified by their locations, i.e., above-ground or underground stations, and by their platform styles, i.e., side or island platforms. However, the effect of the architectural elements on the train noise in stations is not well understood. The aim of the present study is to determine the different acoustical characteristics of the train noise for each station style. The train noise was evaluated by (1) the A-weighted equivalent continuous sound pressure level (L_Aeq), (2) the amplitude of the maximum peak of the interaural cross-correlation function (IACC), (3) the delay time (τ₁) and amplitude (?₁) of the first maximum peak of the autocorrelation function. The IACC, τ₁ and ?₁ are related to the subjective diffuseness, pitch and pitch strength, respectively. Regarding the locations, the L_Aeq in the underground stations was 6.4 dB higher than that in the above-ground stations, and the pitch in the underground stations was higher and stronger. Regarding the platform styles, the L_Aeq on the side platforms was 3.3 dB higher than on the island platforms of the above-ground stations. For the underground stations, the L_Aeq on the island platforms was 3.3 dB higher than that on the side platforms when a train entered the station. The IACC on the island platforms of the above-ground stations was higher than that in the other stations.     

Supercontinuum generation in square photonic crystal fiber with nearly zero ultra-flattened chromatic dispersion and fabrication tolerance analysis

This paper presents a simple index-guiding square photonic crystal fiber (SPCF) where the core is surrounded by air holes with two different diameters. The proposed design is simulated through an efficient full-vector modal solver based on the finite difference method with anisotropic perfectly matched layers absorbing boundary condition. The nearly zero ultra-flattened dispersion SPCF with low confinement loss, small effective area as well as broadband supercontinuum (SC) spectra is targeted. Numerical results show that the designed SPCF has been achieved at a nearly zero ultra-flattened dispersion of 0 ± 0.25 ps/(nm·km) in a wavelength range of 1.38 μm to 1.89 μm (510 nm band) which covers E, S, C, L and U communication bands, a low confinement loss of less than 10⁻⁷ dB/m in a wavelength range of 1.3 μm to 2.0 μm and a wide SC spectrum (FWHM = 450 nm) by using picosecond pulses at a center wavelength of 1.55 μm. We then analyze the sensitivity of chromatic dispersion to small variations from the optimum value of specific structural parameters. The proposed index-guiding SPCF can be applicable in supercontinuum generation (SCG) covering such diverse fields as spectroscopy applications and telecommunication dense wavelength division multiplexing (DWDM) sources.     

Motion Capture and Manipulation of a Single Synthetic Molecular Rotor by Optical Microscopy

Single‐molecule imaging and manipulation with optical microscopy have become essential methods for studying biomolecular machines; however, only few efforts have been directed towards synthetic molecular machines. Single‐molecule optical microscopy was now applied to a synthetic molecular rotor, a double‐decker porphyrin (DD). By attaching a magnetic bead (ca. 200 nm) to the DD, its rotational dynamics were captured with a time resolution of 0.5 ms. DD showed rotational diffusion with 90° steps, which is consistent with its four‐fold structural symmetry. Kinetic analysis revealed the first‐order kinetics of the 90° step with a rate constant of 2.8 s^?1. The barrier height of the rotational potential was estimated to be greater than 7.4 kJ mol^?1 at 298 K. The DD was also forcibly rotated with magnetic tweezers, and again, four stable pausing angles that are separated by 90° were observed. These results demonstrate the potency of single‐molecule optical microscopy for the elucidation of elementary properties of synthetic molecular machines.     

Chemoselective and Direct Functionalization of Methyl Benzyl Ethers and Unsymmetrical Dibenzyl Ethers by Using Iron Trichloride

Methyl and benzyl ethers are widely utilized as protected alcohols due to their chemical stability, such as the low reactivity of the methoxy and benzyloxy groups as leaving groups under nucleophilic conditions. We have established the direct azidation of chemically stable methyl and benzyl ethers derived from secondary and tertiary benzyl alcohols. The present azidation chemoselectively proceeds at the secondary or tertiary benzylic positions of methyl benzyl ethers or unsymmetrical dibenzyl ethers and is also applicable to direct allylation, alkynylation, and cyanation reactions, as well as the azidation. The present methodologies provide not only a novel chemoselectivity but also the advantage of shortened synthetic steps, due to the direct process without the deprotection of the methyl and benzyl ethers.     

Iron‐Catalyzed Friedel–Crafts Benzylation with Benzyl TMS Ethers at Room Temperature

Friedel–Crafts benzylations between unactivated arenes and benzyl alcohol derivatives are clean and straightforward processes to construct biologically useful di‐ and tri‐arylmethanes. We have established an efficient iron‐catalyzed Friedel–Crafts benzylation method at room temperature that uses benzyl TMS ethers as substrates, which are poorly reactive under common nucleophilic substitution conditions. The reaction seems to progress through iron‐catalyzed self‐condensation of the benzyl TMS ether to the corresponding dibenzylic ether. The use of excess arene relative to benzyl TMS ether produced mono‐benzylated arene (di‐ and tri‐arylmethane products), whereas the use of excess benzyl TMS ether versus arene provided bis‐benzylated arene (polyarylated products) in high yields and regioselectivities. In previous methods, the latter double Friedel–Crafts benzylations hardly proceed.     

Direct α‐Siladifluoromethylation of Lithium Enolates with Ruppert‐Prakash Reagent via CF Bond Activation

The direct α‐siladifluoromethylation of lithium enolates with the Ruppert–Prakash reagent (CF₃TMS) is shown to construct the tertiary and quaternary carbon centers. The Ruppert–Prakash reagent, which is versatile for various trifluoromethylation as a trifluoromethyl anion (CF₃^?) equivalent, can be employed as a siladifluoromethyl cation (TMSCF₂⁺) equivalent by C?F bond activation due to the strong interaction between lithium and fluorine atoms.     

Faithful and unfaithful students in time series learning

A model neuron with delay line feedback connections can learna time series generated by another neuron. In the case thatboth neurons have identical transfer functions, a model neuron(student) is capable of reproducing the instruction sequencegenerated by another neuron (teacher), but the parameters arenot uniquely determined by learning a quasi-periodic time series.A student that has completed the learning can be either faithfulor unfaithful, depending on whether it continues mimicking theteacher's time series over a long interval after the learningor whether it departs from the teacher and eventually generatesa time series that bears no resemblance to the teacher's. Inthe case that both neurons have different transfer functions,a student is generally incapable of reproducing the instructionsequence. Each student readjusts its parameters so as to minimizethe mean-squared deviation between the instruction signal andits own output, but this parameter set is not uniquely determined.In this unrealizable learning, the degeneracy among faithfulstudents is lifted and there is no more distinction betweenfaithful and unfaithful students.     

Measurements of Optical Trapping Efficiency for Micron-Sized Dielectric Particles in Various Surrounding Media

The maximum axial trapping efficiency Q_max has been measured in water, ethanol, butanol and octanol for polystyrene latex spheres having a diameter of 2–15μm. The effects of the diameter of the particle as well as the refractive index and the viscosity of surrounding medium have been investigated. For particles of d≥7 μm, Q_max is almost independent of particle size, while it decreases as the diameters decrease to d≦5 μm. It is also noted that Q_max is affected by the viscosity rather than the refractive index of the surrounding medium.     

Morphological study on diffusion‐limited aggregates of poly(ethylene oxide) on alkali halides

When poly(ethylene oxide) was crystallized on a fresh cleavage surface of alkali halides from solution in isoamyl acetate, diffusion‐limited‐aggregate dendrites were formed. Their patterns varied, depending on the kind of substrate on which the poly(ethylene oxide) crystallized: On a KCl substrate, rather ordered dendrites grew with fibrillar crystallites aligning roughly in the 〈110〉_KCl direction, and coarse dendritic clusters formed on NaCl and KBr during the initial stage of their growth. The dendrites grew and matured to sheet the whole surface of alkali halides with a uniform thickness, and subsequently, tetragonal lamellae formed on it through the spiral growth mechanism or the primary nucleation process. Tetragonal lamellar crystals grew with their diagonals parallel to fibrillar crystallites of dendrites. Their orientation did not result from direct, epitaxial contact with the alkali halide substrate but depended on the fibrillar orientation of the underlying sheeted layer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2421–2430, 2002     

In Vivo Laser Tomographic Imaging of Mouse Leg by Coherent Detection Imaging Method

The coherent detection imaging (CDI) technique based on the optical heterodyne detection method enables selective filtering of the directional coherent retaining emergent photons from biological tissues with a highly scattering nature. Therefore, the CDI can acquire on-axis information in the transillumination mode and use the same data-acquisition protocol and reconstruction algorithm as those in X-ray computed tomography (CT). Although the CDI-based laser CT cannot image thick subjects such as the head and chest, it can delineate subjects with a thickness up to several cm at a spatial resolution of sub-millimeters. We are planning to apply the technique to early diagnosis of rheumatoid arthritis (RA). Here, we performed an experiment using mice to confirm the feasibility. We compared in vivo CT images at the level of ankle joints of two mice, one normal and the other with collagen induced arthritis (CIA) as an RA model, and demonstrated that there occur significant discrepancies between the two distributions of image intensities, i.e., reconstructed scattering coefficients in each region of interest (ROI) prepared. We suggest that combining the morphological information with the quantitative information can be effective for early diagnosis of bone diseases and disorders such as rheumatoid arthritis.