Traffic states and jamming transitions induced by a bus in two-lane traffic flow

We study the traffic states and jamming transitions induced by a bus (slow car) in a two-lane traffic of cars. We use the dynamic model which is an extended one of the optimal velocity model to take into account the lane changing. The fundamental (flow-density) diagram is presented. The fundamental diagram changes highly by introducing a bus on a two-lane roadway. It is found that there are the six distinct states for the two-lane traffic flow including a bus. The spatio-temporal patterns are presented for the distinct traffic states. The dynamical state of traffic changes with density of cars. It is shown that the dynamical transitions among the distinct traffic states occur at some values of density. The phase diagram (region map) is shown for the two-lane traffic flow including a bus.     

Segmentation of CT brain images using unsupervised clusterings

In this paper, we present non-identical unsupervised clustering techniques for the segmentation of CT brain images. Prior to segmentation, we enhance the visualization of the original image. Generally, for the presence of abnormal regions in the brain images, we partition them into 3 segments, which are the abnormal regions itself, the cerebrospinal fluid (CSF) and the brain matter. However, for the absence of abnormal regions in the brain images, the final segmented regions will consist of CSF and brain matter only. Therefore, our system is divided into two stages of clustering. The initial clustering technique is for the detection of the abnormal regions. The later clustering technique is for the segmentation of the CSF and brain matter. The system has been tested with a number of real CT head images and has achieved satisfactory results.     

Glass transition and its characteristic length for thin crosslinked polystyrene shells of rodlike capsules

Rodlike capsules consisting of a calcium carbonate core and a crosslinked polystyrene shell were synthesized, and the glass transition temperature (T_g) and characteristic length of the glass transition ξ(T_g) for the thin outer shells were investigated by temperature‐modulated differential scanning calorimetry. The shell thickness ranged from 20 to 129 nm. The ratio of the T_g for the outer shell to the bulk T_g increases with decreasing shell thickness d. The d‐dependence of T_g is interpreted in terms of a simple two‐layer model which assumes that an immobile layer exists near the core‐shell interface. Shells of hollow capsules unexpectedly exhibit a similar d‐dependence of T_g to that for the filled capsules. This is characteristic of the crosslinked polymeric shells, and is attributed to certain spatial heterogeneity of crosslink distribution, and/or to the unstable configuration in the ultrathin shell that does not undergo relaxation due to the crosslink. The latter idea is based on the assumption that unstable configurational state is responsible for the T_g shift from the bulk value observed for nanosized polymeric materials. The ratio of the characteristic length for the shell of the filled capsule to that of the bulk ξ_f(T_g)/ξ_b(T_g) decreases with decreasing d. The results are interpreted in terms of the configurational entropy, and it is also suggested that the configurational state of network polymer chains in the shell affects the characteristic length. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2116–2125, 2008     

Polysaccharide‐templated twisted assemble of 2‐anilinonaphthalene‐6‐sulfonic acid

Schizophyllan (SPG) is a natural β‐1,3‐glucan that forms a triple helix (t‐SPG) in neutral aqueous solutions and t‐SPG can be denatured to single chains (s‐SPGs) in DMSO or alkaline solutions. Exchanging the denatured solutions for neutral water leads the renaturation of the triple helix. We have reported that hydrophobic molecules can form a complex with s‐SPG when they are present in the renaturation process. Some of these, for example poly(dA) and polyaniline, were found to have aromatic amino moieties. This report demonstrates whether s‐SPG can interact with other aromatic amino compounds such as anilinonaphthalene sulfonic acid (ANS) derivatives. Enhanced fluorescence intensity and red‐shifted UV absorption spectra were observed in the mixture of s‐SPG and 2,6‐ANS or 2,6‐TNS. In the circular dichroism measurement, the positive Cotton effects appeared after mixing 2, 6‐ANS with s‐SPG. When the amino proton was replaced by the methyl group or used in intramolecular hydrogen bonds, any spectral changes were not observed. These results indicate that amino proton in the ANS derivatives plays a key role in the complexation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1440–1448, 2008     

Electron energy loss spectroscopy of ultrathin pentacene field effect transistors

Electron energy loss spectra of ultrathin pentacene field effect transistors were measured by applying gate bias voltages. Tailing and shouldering of the primary peak on the energy loss side was observed for 1.5 nm thick films when a negative gate bias was applied. The energy loss spectra obtained from the deconvolution of the primary electron profile showed peaks, and the peak energies increased as a function of the gate bias voltage. This is consistent with the behavior of two-dimensional plasmons of field-induced carriers. The thickness dependence is explained by the thickness of the accumulation layer and the probing depth of the spectroscopy.     

Bi surfactant effects of Co/Cu multilayered films prepared by sputter deposition

The influence of a Bi surfactant layer on the structural and magnetic properties of Co/Cu multilayers grown onto Cu(1 1 0) buffer layer by RF magnetron sputtering has been studied. The results of X-ray diffraction revealed the initial deposition of a 2.0 Å-thick Bi layer onto the Cu buffer layer prior to the deposition of the Co/Cu multilayer yielded high-quality fcc-(1 1 0) oriented epitaxial films. The X-ray photoelectron spectra revealed that Bi was segregated at around the top of the surface. Therefore, Bi was concluded to be an effective surfactant to enhance the epitaxial growth of Co/Cu(1 1 0) multilayer. The maximum giant magnetoresistance and antiferromagnetic interlayer coupling ratios of the Co/Cu multilayers were increased by using the Bi surfactant layer.     

Disordered loop model and coupled conformal field theories

A family of models for fluctuating loops in a two-dimensional random background is analyzed. The models are formulated as O(n) spin models with quenched inhomogeneous interactions. Using the replica method, the models are mapped to the M→0 limits of M-layered O(n) models coupled each other via _1,3 primary fields. The renormalization group flow is calculated in the vicinity of the decoupled critical point, by an epsilon expansion around the Ising point (n=1), varying n as a continuous parameter. The one-loop beta function suggests the existence of a strongly coupled phase (0<n<n_*) near the self-avoiding walk point (n=0) and a line of infrared fixed points (n_*<n<1) near the Ising point. For the fixed points, the effective central charges are calculated. The scaling dimensions of the energy operator and the spin operator are obtained up to two-loop order. The relation to the random-bond q-state Potts model is briefly discussed.     

A study of chiral recognition for NBD-derivatives on a Pirkle-type chiral stationary phase.

A chiral stationary phase (CSP 1) derived from an (S)-N-3,5-dinitrobenzoyl-1-naphthylglycine showed excellent enantiomeric separation for amino acid derivatives with a fluorogenic reagent, 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), in high-performance liquid chromatography (HPLC). We compared elution profiles (separation factor and elution order) of NBD-amino acids and their analogs on HPLC, to determine the diastereomeric complex between the chiral moiety of CSP 1 and NBD-amino acid, which is responsible for the chiral recognition. (1)H-NMR studies of a mixture of model compound of CSP 1 and NBD-Ala suggest that the diastereomeric complex is composed of two hydrogen bonding sites at the amino proton and oxygen atom, and a pi-pi interaction by the benzofurazan structure (2,1,3-benzoxadiazole) of NBD-amino acid. Furthermore CSP 1 was able to separate esters, amides and alpha-methyl amino acids derivatized with NBD-F.