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Study Objectives We conducted a prospective study to quantify motor activity during sleep measured by actigraphy before and after 3 months of treatment with clonazepam in patients with video-polysomnography (vPSG) confirmed isolated rapid eye movement (REM) sleep behavior disorder (iRBD). Methods The motor activity amount (MAA) and the motor activity block (MAB) during sleep were obtained from actigraphy. Then, we compared quantitative actigraphic measures with the results of the REM sleep behavior disorder questionnaire for the previous 3-month period (RBDQ-3M) and of the Clinical Global Impression-Improvement scale (CGI-I), and analyzed correlations between baseline vPSG measures and actigraphic measures. Results Twenty-three iRBD patients were included in the study. After medication treatment, large activity MAA dropped in 39% of patients, and the number of MABs decreased in 30% of patients when applying 50% reduction criteria. 52% of patients showed more than 50% improvement in either one. On the other hand, 43% of patients answered “much or very much improved” on the CGI-I, and RBDQ-3M was reduced by more than half in 35% of patients. However, there was no significant association between the subjective and objective measures. Phasic submental muscle activity during REM sleep was highly correlated with small activity MAA (Spearman’s rho = 0.78, p < .001) while proximal and axial movements during REM sleep correlated with large activity MAA (rho = 0.47, p = .030 for proximal movements, rho = 0.47, p = .032 for axial movements). Conclusions Our findings imply that quantifying motor activity during sleep using actigraphy can objectively assess therapeutic response in drug trials in patients with iRBD.

Nilotinib is a Bcr-Abl tyrosine kinase inhibitor used to treat chronic myelogenous leukemia. There have been case reports of nilotinib-related vasculopathy. However, most cases present peripheral artery disease, whilst reports of nilotinib-related cerebrovascular disease are quite uncommon. Herein, we report a case of nilotinib-induced intracranial stenosis in a patient with recurrent transient ischemic attacks and discuss the results of serial vessel wall magnetic resonance imaging.

Isolated middle cerebral artery dissection and primary angiitis of the central nervous system are two rare but serious causes of ischemic stroke in children. We report a case of a patient who presented with headache, left-sided hemiparesis, and left hemi-hypoesthesia with acute cerebral infarction in the right middle cerebral artery territory. Brain magnetic resonance imaging showed isolated right middle cerebral artery dissection with arterial wall contrast enhancement extending beyond the length of the dissection and diffuse narrowing with stenosis in the right posterior cerebral artery suggesting angiitis. After exclusion of other diagnoses the patient was treated with corticosteroids and dual antiplatelet therapy. Follow up magnetic resonance imaging performed 4 months later showed partially improved contrast enhancement in the right middle cerebral artery and persistent narrowing and focal stenosis of the right posterior cerebral artery. Although rare, primary angiitis of the central nervous system should be considered in the differential diagnosis of acute stroke in children. High-resolution vessel wall imaging magnetic resonance studies can provide important information in determining the etiology of stroke.

Introduction Idiopathic Rapid eye movement (REM) sleep behavior disorder is a condition that can be an early sign of alpha-synuclein-mediated neurodegenerative diseases, and the course of the disease can vary greatly from patient to patient. It is important to identify patients who are at risk of developing neurodegenerative diseases in the future for the purpose of future clinical trials and for patients to plan their lives accordingly. Previous research has identified various risk factors for phenoconversion in RBD patients, but these studies are not practical for use in clinical settings due to resource availability or the rarity of certain features. Additionally, most of these studies have been conducted on non-Asian populations, which may have different genetic backgrounds than Asian populations. This study aimed to develop a machine learning model to predict survival in RBD patients using clinical features commonly available in routine clinical settings. Methods This study recruited patients diagnosed with RBD based on polysomnography results and collected 34 features for each patient. Missing data were imputed and various models were applied to the data to improve performance. The model's predictive performance was evaluated using an integrated Brier score and the concordance index. Mean performance indicators were calculated from 5-fold cross-validation results. A web application hosting the final prediction model was developed and deployed on a server for use by physicians or patients. Results 173 patients were included in the study. We used the likelihood ratio test to calculate the p-values of all variables and selected the following 8 variables with p-values less than 0.1: UPDRS part III, age, history of antidepressant use, history of alcohol use, MoCA (Montreal Cognitive Assessment), PSQI-TST (Pittsburgh Sleep Quality Index - total sleep time), AHI-REM (apnea-hypopnea index - REM sleep), and education level. The random survival forest model had the best mean IBS of 0.07 and the best C-index of 0.93 Conclusion We showed that it is possible for a machine learning model to predict phenoconversion in patients with RBD using features that are commonly available in routine clinical settings Support (if any)

This study proposes a new way of estimating the hole direction to reduce the search time deviation in peg-in-hole assembly. To perform a peg-in-hole assembly, the hole position has to be found. In our previous studies, we found the hole using a blind search method. The blind search method moves the peg in a predefined path until it finds the hole. However, using blind search, it is difficult to predict the peg-in-hole assembly completion time because hole position search time is different each time. This is because the peg moves along the same predefined path without considering the hole direction. Furthermore, if the direction of the hole is known, the hole search time deviation can be reduced compared to when the direction of the hole is not known at all. Therefore, we propose a new way of finding the hole direction using in-hand manipulation based on ‘kinesthetic sensing’. Additionally, we introduce the concept of ‘Free-Finger’ for in-hand manipulation. The proposed method uses fingers to find the hole direction and perform the peg-in-hole assembly. Hence, we can implement peg-in-hole assembly regardless of the performance of the manipulator. The feasibility of the proposed method was verified through experiments using a three-fingered gripper.

Botulism is a neuroparalytic disease caused by a neurotoxin produced by Clostridium botulinum. This study aimed to genetically characterize C. botulinum strain isolated from the first case of infant botulism in Korea reported on June 17, 2019. We isolated C. botulinum strain CB-27 from a stool sample of the patient and analyzed the toxin types and toxin gene cluster compositions of the strain using a mouse bioassay, real-time PCR, and genome sequencing. Toxin gene cluster analysis showed that strain CB-27 possesses a C. botulinum neurotoxin type A harboring an unexpressed B gene. Although the nucleotide and amino acid sequences of toxin genes as well as the toxin gene cluster arrangements in strain CB-27 were identical to those of the known strain CDC_69094, the total nucleotide sequences of the toxin gene clusters of CB-27 differed from those of CDC_69094 by 0.47%, indicating genetic diversity of toxin gene clusters of CB-27 among other previously reported C. botulinum strains. To our knowledge, this is the first description of a C. botulinum strain with two separate toxin gene clusters in Korea.

Introduction More than 80% of patients of isolated rapid eye movement (REM) sleep behavior disorder (iRBD), a prodromal disease of α-synucleinopathies, progress to neurological disease like Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Resting-state EEG measurements taken at baseline have been related to the phenoconversion. The timing of the conversion and the disease to which it will convert are crucial issues in iRBD. This work used baseline EEG in iRBD to create a prediction model for the phenoconversion time and subtype of α-synucleinopathy. Methods Resting-state EEG and neurological assessments were performed at baseline on patients with iRBD. EEG spectral power, Shannon entropy and weighted phase lag index were employed as features. Four models were used to predict subtypes for the PD-MSA and DLB groups, and three models were used to predict survival. External validation was also performed. Results 29 patients out of 143 who were followed up to nine years (mean 3.4 years) later developed α-synucleinopathies (14 PD, 9 DLB, 6 MSA). With a concordance index of 0.8130 and an integrated Brier score of 0.0921, the random survival forest was the best model for predicting survival. For the subtype prediction analysis, the model with the highest accuracy, extreme gradient boosting, had an accuracy of 86.52%. Both models indicated a high importance on EEG slowing related features. Conclusion It is possible to predict the timing and subtype of phenoconversion in iRBD using machine learning models of using EEG biomarkers. To confirm our findings, further study is required, including large sample data from various countries. Support (if any)

Objective This study tested the validity and reliability of the Behavior Development Screening for Toddlers-Questionnaire-Parents (BeDevel-Q/P), a new autism spectrum disorder (ASD) screening instrument being developed in South Korea. The parents of 24-35-month-old infants were recruited to complete the questionnaire. Methods The participants were 791 infants aged 24-35 months. There were 623 typically developing infants, 88 infants with ASD, and 80 developmentally delayed infants. For test-retest, the participants were surveyed every 1-4 weeks. Participants were recruited nationwide. Subjects' parents completed the BeDevel-Q/P and concurrent validity questionnaires. The data were used for statistical analysis. Results A total of 24 items consisting of 16 items from factor 1 (F1), 6 items from factor 2 (F2), and 2 items from factor 3 (F3), were selected for the final BeDevel-Q/P items. Conclusion The factors of the screening instrument developed in this study were analyzed, and three factors were extracted, confirming the theoretical foundation of the BeDevel-Q for the parents of 24-35-month-old infants.

Objectives Early detection of developmental issues in infants and necessary intervention are important. To identify the comorbid conditions, a comprehensive evaluation is required. The study’s objectives were to 1) generate scale items by identifying and eliciting concepts relevant to young children (12–71 months) with developmental delays, 2) develop a comprehensive screening tool for developmental delay and comorbid conditions, and 3) assess the tool’s validity and cut-off. Methods Multidisciplinary experts devised the “Infant Comprehensive Evaluation for Neurodevelopmental Delay (ICEND),” an assessment method that comes in two versions depending on the age of the child: 12–36 months and 37–71 months, through monthly seminars and focused group interviews. The ICEND is composed of three parts: risk factors, resilience factors, and clinical scales. In parts 1 and 2, there were 41 caretakers responded to the questionnaires. Part 3 involved clinicians evaluating ten subscales using 98 and 114 questionnaires for younger and older versions, respectively. The Child Behavior Checklist, Strengths and Difficulties Questionnaire, Infant- Toddler Social Emotional Assessment, and Korean Developmental Screening Test for Infants and Children were employed to analyze concurrent validity with the ICEND. The analyses were performed on both typical and high-risk infants to identify concurrent validity, reliability, and cut-off scores. Results A total of 296 people participated in the study, with 57 of them being high-risk (19.2%). The Cronbach’s alpha was positive (0.533–0.928). In the majority of domains, the ICEND demonstrated a fair discriminatory ability, with a sensitivity of 0.5–0.7 and specificity 0.7–0.9. Conclusion The ICEND is reliable and valid, indicating its potential as an auxiliary tool for assessing neurodevelopmental delay and comorbid conditions in children aged 12–36 months and 37–71 months.

With soaring oil prices worldwide, determining the most optimal routes for economical ship operation has become an important issue. Optimizing ship routes is economically important for ship operation, but it is also essential to meet the standards of environmental regulations recently imposed by the International Maritime Organization. For this purpose, various algorithms for determining ship routes have been developed to ensure the economical operation of ships via utilization of marine climate data and Automatic Identification System (AIS) data. However, such algorithms require a large amount of computational time and do not provide optimal routes because they do not consider practical operating conditions, such as weather and ocean conditions. In this study, an improved A* algorithm using AIS and weather data is proposed to overcome the limitation of the original A* algorithm, one of the most widely used path-finding algorithms. The improved A* algorithm uses an adaptive grid system that efficiently explores nodes according to map grid deformation by latitude. It finds economical routes by minimizing the estimated time of arrival generated by machine learning through 16-way node exploration. For verification of the proposed method, the original A* algorithm and improved A* algorithm were compared through a case study.

Conventional assembly methods using robots need to change end-effectors or operate two robot arms for assembly. In this study, we propose a screwdriving gripper that can perform the tasks required for the assembly using a single robot arm. The proposed screwdriving gripper mimics a human-two-handed operation and has three features: (1) it performs pick-and-place, peg-in-hole, and screwdriving tasks required for assembly with a single gripper; (2) it uses a flexible link that complies with the contact force in the environment; and (3) it employs the same joints as the pronation and supination of the wrist, which help the manipulator to create a path. We propose a new gripper with 3 fingers and 12 degrees of freedom to implement these features; this gripper is composed of grasping and screwdriving parts. The grasping part has two fingers with a roll-yaw-pitch-pitch joint configuration. Its pitch joint implements wrist pronation and supination. The screwdriving part includes one finger with a roll-pitch-pitch joint configuration and a flexible link that can comply with the environment; this facilitates compliance based on the direction of the external force. The end of the screwdriving finger has a motor with a hex key attached, and an insert tip is attached to the back of the motor. A prototype of the proposed screwdriving gripper is manufactured, and a strategy for assembly using a prototype is proposed. The features of the proposed gripper are verified through screwdriving task experiments using a cooperative robotic arm. The experiments showed that the screwdriving gripper can perform tasks required for the assembly such as pick and place, peg-in-hole, and screwdriving.

Molecular imaging is a powerful method for tracking various infectious disease-causing pathogens in host organisms. Currently, a dual molecular imaging method that can provide temporal and spatial information on infected hosts at the organism, organ, tissue, and cellular levels simultaneously has not been reported for Burkholderia pseudomallei, a high-risk pathogen that causes melioidosis. In this study, we have established an experimental method that provides spatiotemporal information on infected hosts using luminescent and fluorescent dual-labeled B. pseudomallei. Using this method, we visualized B. pseudomallei infection at the organism, organ, and tissue levels in a BALB/c mouse model by detecting its luminescence and fluorescence. The infection of B. pseudomallei at the cellular level was also visualized by its emitted fluorescence in infected macrophage cells. This method could be an extremely useful and applicable tool to study the pathogenesis of B. pseudomallei-related infectious diseases.

We report here the draft genome sequence of Burkholderia pseudomallei H0901. This strain was isolated in 2003 from the first melioidosis patient in South Korea.

Molecular imaging is a powerful method for tracking various infectious disease-causing pathogens in host organisms. Currently, a dual molecular imaging method that can provide temporal and spatial information on infected hosts at the organism, organ, tissue, and cellular levels simultaneously has not been reported for

A composite box-girder with corrugated steel webs has been used in civil engineering practice as an alternative to the conventional pre-stressed concrete box-girder because of several advantages, such as high shear resistance without vertical stiffeners and an increase in the efficiency of pre-stressing due to the accordion effect. Many studies have been conducted on the shear buckling and flexural behavior of the composite box-girder with corrugated steel webs. However, the torsional behavior is not fully understood yet, and it needed to be investigated. Prior study of the torsion of the composite box-girder with corrugated steel webs has been developed by assuming that the concrete section is cracked prior to loading and doesn't have tensile resistance. This results in poor estimation of pre-cracking behaviors, such as initial stiffness. To overcome this disadvantage of the previous analytical model, an improved analytical model for torsion of the composite box-girder with corrugated steel webs was developed considering the concrete tension behavior in this study. Based on the proposed analytical model, a non-linear torsional analysis program for torsion of the composite box-girder with corrugated steel webs was developed and successfully verified by comparing with the results of the test. The proposed analytical model shows that the concrete tension behavior has significant effect on the initial torsional stiffness and cracking torsional moment. Finally, a simplified torsional moment-twist angle relationship of the composite box-girder with corrugated steel webs was proposed based on the proposed analytical model.

This paper presents field test result of an LDM-based mobile broadcasting system, and analyze the results based on reception power (or field strength) and erroneous second ratio (ESR).

Development of stereo- and regioselective living alkene polymerization catalysts has led to the capability to produce multiblock copolymers with semicrystalline syndiotactic polypropylene blocks and poly(ethylene-co-propylene) rubbery blocks that have excellent elastomeric properties, both undiluted and as gels with as little as 8 wt % copolymer in mineral oil. During step cycle mechanical processing, the crystals can plastically deform and partially transform from lamellae into rod-like fibrils, which align along the tensile direction, giving rise to very large tangent moduli at large strains. The dimensions of these aligned fibrils can be established from small-angle X-ray scattering and used to construct models of the large strain elasticity, as well as its evolution with plastic strain, based on short fiber composite theory. Wide angle X-ray scattering experiments as well as FTIR measurements suggest that the oriented fibrils have the transplanar (form III) crystal structure. The large toughness of th...

The structural vibration due to earthquake or outside impact causes serious problem for building safety. A dynamic model of a friction damper which can be constructed and installed easily is needed to reduce the vibration of the building. In this paper, the experimental equation of a circular friction damper is derived and designed for reduction of a earthquake vibration of a building. The developed experimental equation is defined to simply design the capacity on design of the circular friction damper based on the results of the performance test. Finally this experimental equation can be used for the design of a circular friction damper.

For the detection of the impact location in a pipeline system, the correlation method has been the conventional method. For the application of the correlation method, the diameter of a duct should be small so that the acoustic wave inside the duct can propagate with nondispersive characteristics, in the form of, for example, a plane wave. This correlation method calculates the cross-correlation between acoustic waves measured at two acceleration sensors attached to a buried duct. It also gives information about the arrival time delay of an acoustic wave between two sensors. These arrival time delays are used for the estimation of the impact location. However, when the diameter of the duct is large, the acoustic waves inside the duct propagate with dispersive characteristics owing to the reflection of the acoustic wave off of the wall of the duct. This dispersive characteristic is related to the acoustic modes inside a duct. Therefore, the correlation method does not work correctly for the detection of the impact location. This paper proposes new methods of accurately measuring the arrival time delay between two sensors attached to duct line system. This method is based on the time-frequency analyses of the short time Fourier transform (STFT) and continuous wavelet transform (CWT). These methods can discriminate direct waves (non-dispersive waves) and reflective waves (dispersive waves) from the measured wave signals through the time-frequency analysis. The direct wave or the reflective wave is used to estimate the arrival time delay. This delay is used for the identification of the impact location. This systematic method can predict the impact location due to the impact forces of construction equipment with more accuracy than the correlation method.

Gels of syndiotactic polypropylene-b-ethylene-propylene-rubber-b-syndiotactic polypropylene (sPP-EPR-sPP) were prepared by dissolving ∼6 wt % of the triblock copolymer in mineral oil at 170 °C and then cooling to room temperature in several steps to crystallize the sPP block. The gel was subjected to step-cycle processing by first extending it to a given maximum tensile strain, followed by decreasing the load to zero. The cycle was then repeated to a higher maximum strain and so on until the sample either failed or it reached an ultimate predetermined strain. The true stress and true strain eH during each cycle were recorded, including the true strain at zero load eH,p after each cycle that resulted from the plastic deformation of the sPP crystals in the gel. The initial Young’s modulus Einit and maximum tangent modulus Emax in each cycle undergo dramatic changes as a function of eH,p, with Einit decreasing for eH,p ≤ 0.1 and then increasing slowly as eH,p increases to 1 while Emax increases rapidly over ...

The incremental plastic deformation of the crystals of block copolymers made of semicrystalline polypropylene endblocks and amorphous ethylene-r-propylene midblocks occurring during step cycle tensile tests has dramatic effects on the stress-strain curves. This can be understood from the evolution of the morphology and of the microstructure of the crystalline blocks revealed by X-ray scattering experiments.

We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene- block -poly(ethylene- co -propylene)- block -syndiotactic polypropylene and isotactic polypropylene- block -regioirregular polypropylene- block -isotactic polypropylene triblock copolymers were synthesized. The volume fraction and composition of the blocks, as well as the overall size of the macromolecules, were controlled by sequential synthesis of each block of the polymers. These triblock copolymers, with semicrystalline end-blocks and mid-segments with low glass-transition temperatures, show significant potential as thermoplastic elastomers. They have low Young's moduli, large strains at break, and better than 90% elastic recovery at strains of 100% or less. An isotactic polypropylene- block -regioirregular polypropylene- block -isotactic polypropylene- block -regioirregular polypropylene- block -isotactic polypropylene pentablock copolymer was synthesized that also shows exceptional elastomeric properties. Notably, microphase separation is not necessary in the semicrystalline isotactic polypropylenes to achieve good mechanical performance, unlike commercial styrenic thermoplastic elastomers.

The additive effects of the novel ethylene–propylene random (EP) copolymers with high isotacticity in propylene sequence on the morphology and mechanical properties of isotactic polypropylene (iPP) were investigated using polarized optical microscopy, transmission electron microscopy, dynamic mechanical analysis and tensile behavior. According to these results, the EP copolymers with a propylene content of more than 84 mol% were miscible with iPP, in which the crystallizable PP sequences in these EP copolymers were incorporated in crystal lattice of iPP and the other portions in the EP chains were excluded to the amorphous phases. Consequently, they act as tie molecules linking between adjacent lamellae, leading to enhancement of yield toughness of iPP. On the other hand, the EP copolymers with a propylene-unit content of less than 77 mol% were incompatible with iPP. The iPP/EP blends showed the phase-separated morphology.

A series of novel hexene-1–propylene random copolymers with isotactic sequence of propylene was synthesized with a MgCl2-supported Cr(acac)3 catalyst. The molecular weight distribution of copolymers and homopolymers was considerably narrower than that of typical polyolefins produced by heterogeneous Ziegler–Natta catalysts. The crystallizability of the copolymers having a propylene-unit content of more than 50 mol % drastically decreased with decreasing propylene-unit content, and the copolymers with a propylene content of less than 50 mol % were completely amorphous. In the present novel type of random copolymers with crystallizable and noncrystallizable units, a single glass transition was observed between pure polypropylene and polyhexene-1, and a major component was found to govern the final morphology and the mechanical characteristics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2949–2954, 2004

During propylene polymerization with the Cr(acetylacetonate)3/MgCl2–Et2AlCl–ethylbenzoate catalyst system which shows high isospecificity for propylene polymerization, it was found that the chain transfer and termination reactions can be neglected. Based on this result, some stepwise polymerizations of propylene and ethylene were carried out with the same catalyst system varying polymerization conditions. The resulting copolymers were separated by temperature rising elution fractionation (TREF) and afforded two fractions which were eluted at different temperatures. From the 13C NMR, DSC and GPC analyses of each fraction, it was considered that the corresponding block copolymer existed in the fraction eluted at higher temperature. © 2003 Society of Chemical Industry

The adsorbed amounts and interfacial conformations of a low-molecular-weight oligomer of a weak cationic polyelectrolyte (15-unit chain of dimethylaminoethyl methacrylate, DMAEMA) on colloidal silica were examined, with the ultimate intent of providing perspective on the adsorption of high-molecular-weight weak polyelectrolytes. At all but the lowest ionic strengths or highest pHs, over the full range of adsorbed oligomer amounts on each isotherm, the interfacial conformation was relatively insensitive to coverage with train fractions from 0.8 to 1. This occurs because short oligomeric chains are not capable of forming long loops or tails found in higher-molecular-weight homopolymer layers. Variations in pH altered the backbone and surface charge densities, changing the density of contact points for adsorption. This was apparent in the NMR solvent relaxation behavior, which suggested the tightest binding near pH 6, and a sharp drop in the train fraction at high pH, just as the adsorption began to diminish with reduced backbone protonation. Variations in ionic strength screened repulsions among adsorbed oligomers, an effect most apparent at low ionic strengths. NMR solvent relaxation data provided substantial evidence for differences in the anchoring of DMAEMA oligomer and adsorbed trains of a nonionic homopolymer such as polyethylene oxide (T. Cosgrove, M. A. Cohen Stuart, and G. P. van der Beek, Langmuir 7, 327 (1991)). DMAEMA adsorbs at a small number of discrete points on side chains, while with polyethylene oxide the literature suggested every monomer on the main backbone can potentially adhere to the surface, giving a less mobile interface from the perspective of the solvent.

A superoxide dismutase (SOD) gene from Burkholderia pseudomallei, the causative agent of melioidosis, was cloned and expressed in Escherichia coli, and its product was functionally and physically characterized. The gene has an open-reading frame of 579 bp. The deduced amino acid sequence has 192 residues with a calculated molecular mass of ∼22 kDa. Sequence comparison with other bacterial SODs showed that the protein contains typical metal-binding motifs and other Fe-SOD-conserved residues. The sequence has substantial similarity with other bacterial Fe-SOD sequences. The enzymatic activity of the expressed protein was inhibited by hydrogen peroxide but not by sodium azide or potassium cyanide, attributes that indeed are characteristic of typical bacterial Fe-SODs. Western blotting with antiserum against the recombinant Fe-SOD revealed that it is expressed in B. pseudomallei. Transformed E. coli that expressed the Fe-SOD had significantly increased SOD activity and was highly tolerant to paraquat-mediated replication inhibition, compared to transformed cells carrying an empty vector. Our results provide a basis for further biochemical characterization of the enzyme and elucidation of its role in the pathogenesis of B. pseudomallei.

We have investigated the changes in the temperature dependence of the dc conductivity and the optical gap with nitrogen content in amorphous carbon nitride (a-C:N) films, in order to find the effect of nitrogen doping on the electrical and optical properties of amorphous carbon films. Specimens were deposited onto borosilicate glass substrates by the rf magnetron sputtering method using Ar and N2 as a sputtering gas and a reactive one, respectively. The values of the activation energy of the dc conductivity, Ea, of these films are 0.3∼0.8 eV and those of the optical gap, Eg, are 0.8∼ 1.4 eV. Both values decrease with increasing nitrogen content, which is due to the increase of the concentration or average size of sp islands segregated into the sp matrix by nitrogen doping. From the investigation of the behavior of both Ea and Eg in accordance with the nitrogen content, we discuss the three subsequent shifts of band edge and Fermi level, accompanied with the subsequent changes of microstructure in a-CN films by nitrogen doping.

Burkholderia pseudomallei is a gram-negative opportunistic intracellular pathogen that causes an acute and fatal septicemic melioidosis in humans. The organism is mainly found in Southeastern Asia and Northern Australia. Recently, we encountered a case of melioidosis in a Korean patient and performed the laboratory diagnosis of melioidosis. As a result, a gram negative bacterium was isolated from a melioidosis patient, and it was identified as B. pseudomallei on DNA sequencing of 16S ribosomal RNA with 99.9% homology and biochemical examination of VITEK gram-negative identification card. Also, DNA from cultured bacteria was tested in multiplex PCR, a 245 bp fragment amplified from the metalloprotease gene and a fragment of variable size ranging from 400~700 bp resulting from amplification of the 10 bp repetitive element for B. pseudomallei were confirmed after electrophoresis. The bacterium was sensitive to ceftazidime, imipenem and meropenem but resistant to ticarcillin. So far, there are no domestic cases of melioidosis in Korea, however, due to the increase in international travelers, the incidence of melioidosis is likely to increase. We report a recent case of melioidosis in a Korean patient.

Background/Aims: We examined the ischemia-modified albumin (IMA) level during exercise in patients with coronary artery disease (CAD). Methods: Forty patients with a history of chest pain underwent both symptom-limited treadmill exercise stress testing and coronary angiography within one week. During the treadmill tests, blood samples were obtained at baseline and 5 min after exercise to measure the serum IMA level. Results: Of the 40 patients, fourteen (35%, CAD group) had significant coronary artery stenosis, while the other 26 (65%, non-CAD group) did not. The baseline and post-exercise IMA levels in the two groups did not differ significantly (105.2±7.2 vs. 107.7±6.7 U/mL at baseline and 93.1±10.1 vs. 94.8±5.7 U/mL at post-exercise in the CAD and non-CAD groups, p=0.29 and 0.57, respectively). The changes in IMA after exercise did not differ either (-10.4±7.5 vs. -14.0±7.6 U/mL in the CAD and non-CAD groups, respectively, p=0.10). Similarly, the change in IMA between the exercise ECG test positive (TMT positive, n=9) and negative (TMT negative, n=20) groups did not differ (-14.63±5.19, vs -8.50±9.01 U/mL, p=0.15, in the TMT positive and negative groups, respectively). Conclusions: Our results suggest that IMA has limitation in detecting myocardial ischemia during symptom-limited exercise stress tests.

The quasi-linear hyperbolic differential equations governing fluid-hammer phenomena in a two-dimensional plane or axisymmetric system are written as integrals along bi-characteristics and a streamline. A stepwise solution procedure is constructed by replacing the integrals by approximation formulas. Derivatives of dependent variables in directions outside the characteristic cone are eliminated and explicit solutions are obtained by linearly combining the remaining difference relations. Two solution schemes resulting from the two approximation formulas are examined for their numerical stability. Numerical calculations are carried out for a plane acoustic wave diffracting from a 90° sharp corner, and the result is compared with analytical solutions and experiment. Numerical results are further obtained for a simple problem involving a sudden expansion and contraction and the results are compared with one-dimensional acoustic solutions.

A numerical technique based on the method of nearcharacteristics is used for solving nonlinear fluid-transient problems in two-dimensional plane or axisymmetric geometries. The solution procedure is constructed by relating flow conditions through compatibility relations along nearcharacteristic lines which lie in coordinate planes. This leads to an efficient computational technique which is a direct extension of the one-dimensional method of characteristics and which requires only simple one-dimensional interpolations. Because the nearcharacteristics fall outside the characteristic cone, the solution procedure refers directly to conditions outside the true domains of dependence. However, numerical calculations for simple example problems and comparisons with analytical and experimental results show that the nearcharacteristic procedure is in general as accurate as the bicharacteristic method. Von Neumann stability analysis for a linearized version of the numerical procedure reveals that the schemes based on a formulation in a single coordinate plane are unconditionally unstable. However, averaging the two unstable solutions yields a stable procedure with a stability criterion equivalent to that of the bicharacteristic procedure ( cδt δx ⩽ 0.5 ). Numerical experimentation verifies that these findings for the linearized system also apply to the nonlinear procedures. The ease of formulation of the nearcharacteristic equations and the numerical schemes, even for problems involving large numbers of independent variables or multitudes of characteristics, makes this technique attractive for application where alternate methods of characteristic approaches become too cumbersome or outright impossible.