Origin of high-speed modification of refractive index in fusedquartz by vacuum ultraviolet laser irradiation

We report on high-speed modification and a large change of the refractive index on the order of 10^-2 of fused quartz upon vacuum ultraviolet (VUV) laser irradiation. The origin of the large refractive index change is discussed based on the laser-induced color center and surface morphology changes. The VUV-UV absorption spectrum of modified samples indicates the formation of a color center at around 163 nm (≡Si-Si≡defect), which is attributed to bond scission of fused quartz by VUV laser-induced electron excitation. On the other hand, simultaneous UV laser irradiation in our present experimental scheme is responsible for the generation of a surface damage at the large number of pulses, which causes scattering and deterioration of the optical properties of the irradiated regions     

Information Filtering Using User's Context on Browsing in Hypertext

Browsing is one of the most popular ways to gather information in database with hypertext structure. In order to support a user to browse, modeling of the user's interests is one of the most important issues. Although there are several promising methods to infer the interests from the user's browsing behavior, they assume that the interests are consistent during the browsing. However, the user's interests are often strongly dependent on the local context of the browsing. This paper describes a method to model the user's shifting interests from the browsing history. An information filtering method using the model of the interests has been implemented. We call it ‘context-sensitive filtering’. The results of an experimental evaluation, by real users' browsing for an encyclopedia in CD-ROM format, are also reported. This revised version was published online in July 2006 with corrections to the Cover Date.     

Clinical study on azithromycin in 10% fine granules and 100mg capsules in the field of pediatrics

Azithromycin (AZM), a new oral macrolide antibiotic, in 10% fine granules or 100 mg capsules was given to pediatric patients to treat various infections. The following results were obtained in our studies of AZM for its antibacterial activities against clinical isolates, its pharmacokinetics, its efficacy, and its safety. 1. MICs of AZM, erythromycin (EM) and clarithromycin (CAM) were determined against a total of 57 strains all at 10(6) cfu/ml. Among Gram-positive cocci, MICs of AZM ranged from 0.78 to > 100 micrograms/ml against Staphylococcus aureus (20 strains), from 0.05 to 0.1 microgram/ml against Streptococcus pyogenes (11 strains), and from 0.0125 to 3.13 micrograms/ml against Streptococcus pneumoniae (10 strains). These MICs were similar to those of the other macrolides. Among Gram-negative bacilli, MICs of AZM were 0.05 micrograms/ml against Moraxella subgenus Branhamella catarrhalis (1 strain), from 0.78 to 3.13 micrograms/ml against Haemophilus influenzae (9 strains), 0.78 micrograms/ml against Haemophilus parainfluenzae (1 strain) and 6.25 micrograms/ml against salmonella sp. (1 strain). These values were similar to or lower than those of the other macrolides. Against Mycoplasma pneumoniae, MICs of AZM were < or = 0.0008 micrograms/ml in three strains. One strain of M. pneumoniae showed tolerance to AZM at MIC 25 micrograms/ml. The other agents exhibited higher MIC than AZM against this organism. 2. Plasma samples were collected from five patients receiving fine granules and four patients receiving capsules for drug level determination. The patients received AZM at 10.0 approximately 16.3 mg/kg body weight once daily for 3 days. Drug concentrations in plasma at two hours after Day 3 dosing were in a range between 0.02 and 0.19 micrograms/ml for fine granules and were in a range between 0.11 and 0.42 micrograms/ml for capsules. 3. Urine samples were collected from four patients receiving fine granules and four patients receiving capsules. Drug levels were determined to be 3 micrograms/ml at post-treatment 48 hours for fine granules and post-treatment 72 hours for capsules. Urinary excretion rates of AZM in three patients on capsules lied in a range between 4.69 and 10.17%. 4. Effectiveness of AZM in fine granules was evaluated in 128 patients having a total of 19 different infections. AZM was rated "excellent" in 51 patients, "good" in 63, "fair" in 8, "poor" in 6, resulting in an efficacy rate of 89.1%. Effectiveness of AZM in capsular form was evaluated in 23 patients with five different infections. AZM was found "excellent" in 13 patients and "good" in 10, resulting in an efficacy rate of 100%. 5. AZM in fine granules eradicated 45 strains of 54 in 8 different bacteria. AZM in capsules eradicated 9 strains of 10 strains in 6 different bacteria. 6. As for adverse reactions, one patient complained of eruption, one vomiting, one loose stool, five diarrhea, when administered with fine granular form of AZM. One patient on AZM capsules experienced urticaria and vomiting. 7. As for abnormal laboratory changes, three patients were found with decreased WBC, seven with increased eosinophil, two with increased GOT and GPT, one with increased GPT. They were all on fine granular form of AZM. As far as abnormalities found in patients administered with AZM in capsular form, two showed decreased WBC, one decreased WBC along with increased eosinophil, and three increased eosinophil.     

Learning and recall algorithm for optical associative memory using a bistable spatial light modulator

A learning and recall algorithm for optical associative memory based on the conventional correlationlearning method with three effective improvements (sparse-encoding method, constant-total-activity method, and binary memory) is proposed from a viewpoint of practical implementation. It is shown that the algorithm is suitable for implementation with a bistable spatial light modulator such as a ferroelectric liquid-crystal spatial light modulator, which has high resolution and a fast response time. The results of theoretical analysis and simulations indicate that the algorithm permits an associative-memory system with a large memory capacity to be realized. An example of an optical system for executing this algorithm is proposed. To determine the performance specifications that are required for the various optical components within the system, we simulate and evaluate the effect of noise (which is caused by nonideal components) on system performance. These results show that the system is robust in the presence of predicted noise levels.     

Simple wide-range method for angle measurement with a point fiber-optic output

We propose a simple optical method for precise, wide-range angle measurement based on the use of a single-mode optical fiber as a registration scheme output. Because of its micrometric core dimensions, the fiber serves as a point receiver that is highly sensitive to angular displacements of focused laser emission. The method allows the independent photoelectric measurement of both rotation and spatial angles of various optical elements, combining a wide angular dynamic range (from 0 degrees to 360 degrees ) with high accuracy (exceeding 3 arcsec).     

A framework for ICAI systems based on inductive inference and logic programming

The main components of an Intelligent Computer-Assisted Instruction (ICAI) system are the expertise, the student model and tutoring strategies. The student model manages what the student dose and dose not understand, and the performance of an ICAI system depends largely on how well the student model approximates the human student. We propose a new framework for ICAI systems which uses the inductive inference for constructing the student model from the student’s behavior. In the framework, both the expertise and the student model are represented as Prolog programs, which enables to express the meta-knowledge that is the knowledge of how to use the knowledge. Since the construction of the student models is performed independently of the expertise, the framework is domain-independent. Therefore, an ICAI system for any subject area can be built with the framework. As an example, the ICAI system teaching chemical reaction is presented together with a sample performance. The authors believe that the new framework for ICAI systems based on logic programming and inductive inference could be a breakthrough of the future ICAI systems.     

Pattern discovery in data streams under the time warping distance

Subsequence matching is a basic problem in the field of data stream mining. In recent years, there has been significant research effort spent on efficiently finding subsequences similar to a query sequence. Another challenging issue in relation to subsequence matching is how we identify common local patterns when both sequences are evolving. This problem arises in trend detection, clustering, and outlier detection. Dynamic time warping (DTW) is often used for subsequence matching and is a powerful similarity measure. However, the straightforward method using DTW incurs a high computation cost for this problem. In this paper, we propose a one-pass algorithm, CrossMatch, that achieves the above goal. CrossMatch addresses two important challenges: (1) how can we identify common local patterns efficiently without any omission? (2) how can we find common local patterns in data stream processing? To tackle these challenges, CrossMatch incorporates three ideas: (1) a scoring function, which computes the DTW distance indirectly to reduce the computation cost, (2) a position matrix, which stores starting positions to keep track of common local patterns in a streaming fashion, and (3) a streaming algorithm, which identifies common local patterns efficiently and outputs them on the fly. We provide a theoretical analysis and prove that our algorithm does not sacrifice accuracy. Our experimental evaluation and case studies show that CrossMatch can incrementally discover common local patterns in data streams within constant time (per update) and space.     

Estimation of conductivity and permittivity of water trees in PEfrom space charge distribution measurements

Using an improved pulsed electroacoustic system which is capable of measuring space charge distribution at minimum intervals of 25 μs, the charge distribution inside water-treed polyethylene (PE) was examined. From the results, the frequency dependencies of conductivity and permittivity were examined for water trees grown in PE. The conductivity of the water-treed region is found to be >10¹⁰× higher than that of non-treed regions, while the permittivity increase is only slight     

Radiation effects in natural quartz crystals

Optically clear, as visually observed, natural quartz crystals of Brazilian and Arkansas origins, which exhibit Al–OH^?-centers in their as-received conditions, have been measured for their low temperature ESR spectra to see the presence of Al-hole centers. The ESR spectra revealed the presence of Al-hole centers in their as-received conditions. These centers showed an increase in their strength upon irradiation with a ⁶⁰C0 source. Such observations were exhibited by Al–OH^?-centers as noticed earlier. The crystals were thus noticed to exhibit the presence of Al–OH^?-centers and also Al-hole centers in their as-received conditions. The observations match with the results on cultured quartz where irradiation breaks away the Al-alkali centers into a mixture of Al–OH^?- and Al-hole centers. It is thus concluded that the natural crystals, which exhibit the presence of these centers in their as-received condition, have been irradiated in nature with a low dose.