On stability and robust stability of positive linear Volterra equations in Banach lattices

We study positive linear Volterra integro-differential equations in Banach lattices. A characterization of positive equations is given. Furthermore, an explicit spectral criterion for uniformly asymptotic stability of positive equations is presented. Finally, we deal with problems of robust stability of positive systems under structured perturbations. Some explicit stability bounds with respect to these perturbations are given.     

Using HDC to evaluate signal similarity for information masking

In the many studies done on informational masking, interfering speech reduces speech intelligibility. This effect is often used to secure privacy in public spaces. These applications require estimates of how much masking is required. In general, masking effects are estimated by using spectrum information as excitation patterns. However, estimates of informational masking can hardly be obtained by only using spectrum information. Therefore, we estimated the effects of informational masking using time-domain information. Then, we calculated the cepstra of the envelopes’ magnitude histograms. If these cepstra are different between the target and the masker, the signals are not similar in the time-domain. Furthermore, the effect of informational masking would be low. Therefore, we considered the histograms’ cepstra distances (HCD) to estimate signal similarities. The signal similarities in our first experiment were estimated using five maskers by utilizing the HCD. These maskers were random noise, music, female speech, male speech, and target speaker’s speech. Male and female speech were more similar to the target speech than music and noise. Also, the same speaker’s speech was the most similar in the set of maskers. A listening test was carried out in the second experiment to verify the HCD. A double masker was used in this experiment as an effective informational masker. It has similar characteristics to reversal speech. The listening test results suggest the double-masker’s masking effects has the same relation with HCD. This suggests informational masking can be estimated by signal similarity using the HCD.     

Adsorption structure of acetic anhydride on a TiO2(1 1 0) surface observed by scanning tunneling microscopy

The carboxylic acids are stably adsorbed on TiO₂(1 1 0) surfaces at room temperature. To demonstrate the neutralization mechanism proposed by Ashima et al. [H. Ashima, W.-J. Chun, K. Asakura, Surf. Sci. 601 (2007) 1822.] that explains the stable adsorption of carboxylic acids, we studied the full-coverage adsorption structure of acetic anhydride on a TiO₂(1 1 0) surface by STM (scanning tunneling microscopy). We directly observed three postulated species on the TiO₂(1 1 0) surface; normal acetates (termed acetate A) forming a (2 × 1) ordered structure, a minor acetate species (termed acetate B) which was present between the bridging oxygen and the 5-fold Ti, and the oxygen vacancies. We determined the ratio of these three species. This ratio was in good agreement with the postulated conversion reaction of acetate B to A.     

High-Field and Multifrequency ESR in the Two-Dimensional Triangular Lattice Antiferromagnet NiGa2S4

We report the experimental results of electron spin resonance in high magnetic fields up to about 53 T on the quasi-two-dimensional triangular lattice antiferromagnet NiGa₂S₄. The temperature dependence of the resonance field at 584.8 GHz shows a steep change below about 30 K, indicating a development of the short-range correlation. The frequency dependence of the resonance field at the lowest temperature for H∥c is explained by one of the helical resonance modes. These experimental results suggest that the short-range order is well developed at low temperatures, and the resonance mode is described by a conventional spin wave theory.     

Ruthenium Trichloride-Catalyzed Allyl Ether Formation

Ruthenium complexes are well known to catalyze the oxidation of alcohols,¹ where a ruthenium alkoxide has been assumed as a key intermediate. The formation of symmetrical ethers from certain carbinols is also catalyzed by ruthenium in a similar manner.² We now wish to report that the mixed etherification of allyl alcohols is catalyzed by RuCl₃, which acts as a Lewis acid to cleave the allylic carbon—oxygen bond.     

Gambieroxide,a novel epoxy polyether compound from the dinoflagellate Gambierdiscus toxicus GTP2 strain

A novel epoxy polyether compound named gambieroxide was isolated from the benthic dinoflagellate Gambierdiscus toxicus (GTP2 strain) collected at Papeete, Tahiti, French Polynesia and its structure comprising of a ladder-frame polyether with twelve contiguous trans-fused ether rings (6/7/6/6/6/7/6/8/6/6/6/6), a sulfate ester group, an epoxide, and two olefines in side chains was elucidated by detailed NMR and MS analysis. It is interesting that the structure strikingly resembles yessotoxin, one of lipophilic toxins in shellfish originating from the dinoflagellate Protoceratium reticulatum.     

Eigensystem and full character formula of theW 1+∞ algebra withc = 1

By using the free field realizations, we analyze the representation theory of theW ₁₊ algebra withc = 1. The eigenvectors for the Cartan subalgebra ofW ₁₊ are parametrized by Young diagrams, and explicitly written down byW ₁₊ generators. Moreover, their eigenvalues and full character formula are also obtained.     

A Review of Recent Near Infrared Research for Wood and Paper

Abstract

This review article introduces recent technical and scientific reports in terms of near infrared (NIR) spectroscopy in the wood and paper science and industry, where interest has increased during the last couple decades. Many researchers reported the NIR technique was useful to detect multi information in both chemical and physical properties of wood materials, although it was widely used in a state where characteristic cellular structure was retained. In the case of application of NIR spectroscopy to pulp and paper, many publications have pointed out its high probability as online measurement techniques during paper‐making process control. Arguments referred to the importance of NIR spectroscopy as fundamental and applied research of wood and paper.     

HCC-to-liver contrast on arterial-dominant phase images of EOB-enhanced MRI: comparison with dynamic CT

The purpose of this study was to assess the efficacy of arterial-dominant phase images of gadolinium–ethoxybenzyl–diethylenetriamine pentaacetic acid (EOB)-enhanced magnetic resonance imaging (MRI) for evaluation of arterial blood supply in hepatocellular carcinoma (HCC) in comparison with that of multiphasic dynamic computed tomography (CT). This study comprised 30 patients (22 men and 8 women, mean age: 68.0 years) with 40 pathologically proven HCCs (well differentiated: 3, moderately differentiated: 30, poorly differentiated: 7, mean diameter: 45.1 mm), all of whom underwent EOB-enhanced MRI and dynamic CT preoperative assessment. Regions of interest were placed over HCCs and the adjacent normal liver, and signal intensities or CT values were measured by two experienced abdominal radiologists on the arterial-dominant phase images of EOB-enhanced MRI and dynamic CT images. HCC-to-liver contrasts [Michelson's contrast: C_M=(S_HCC− S_Liver)/(S_HCC+ S_Liver)] were calculated and compared among the modalities. HCC-to-liver contrasts were also visually scored on a 5-point scale and compared. The mean C_M and visual score for dynamic CT were significantly higher than those for EOB-enhanced MRI. Good agreements were obtained among the two observers. Dynamic CT is a more suitable modality than EOB-enhanced MRI for evaluation of arterial blood supply in HCC. This should be taken into account for diagnosis and management of HCC.