Showing papers by "National Cheng Kung University published in 1998"

In Vitro Dissolution Profile Comparison—Statistics and Analysis of the Similarity Factor, f2

Abstract: Purpose To describe the properties of the similarity factor (f2) as a measure for assessing the similarity of two dissolution profiles Discuss the statistical properties of the estimate based on sample means Methods The f2 metrics and the decision rule is evaluated using examples of dissolution profiles The confidence interval is calculated using bootstrapping method The bias of the estimate using sample mean dissolution is evaluated Results 1 f2 values were found to be sensitive to number of sample points, after the dissolution plateau has been reached 2 The statistical evaluation of f2 could be made using 90% confidence interval approach 3 The statistical distribution of f2 metrics could be simulated using 'Bootstrap' method A relatively robust distribution could be obtained after more than 500 'Bootstraps' 4 A statistical 'bias correction' was found to reduce the bias Conclusions The similarity factor f2 is a simple measure for the comparison of two dissolution profiles But the commonly used similarity factor estimate ^f2 is a biased and conservative estimate of f2 The bootstrap approach is a useful tool to simulate the confidence interval

Accelerated degradation tests: modeling and analysis

Abstract: High reliability systems generally require individual system components having extremely high reliability over long periods of time. Short product development times require reliability tests to be conducted with severe time constraints. Frequently few or no failures occur during such tests, even with acceleration. Thus, it is difficult to assess reliability with traditional life tests that record only failure times. For some components, degradation measures can be taken over time. A relationship between component failure and amount of degradation makes it possible to use degradation models and data to make inferences and predictions about a failure-time distribution. This article describes degradation reliability models that correspond to physical-failure mechanisms. We explain the connection between degradation reliability models and failure-time reliability models. Acceleration is modeled by having an acceleration model that describes the effect that temperature (or another accelerating variable) has on...

Plastic deformation and fracture behaviour of Ti–6Al–4V alloy loaded with high strain rate under various temperatures

Abstract: This study investigates the plastic deformation and fracture behaviour of titanium alloy (Ti–6Al–4V) under high strain rates and various temperature conditions. Mechanical tests are performed at constant strain rates ranging from 5×102 to 3×103 s−1 at temperatures ranging from room temperature to 1100°C by means of the compressive split-Hopkinson bar technique. The material's dynamic stress–strain response, strain rate, temperature effects and possible deformation mechanisms are discussed. Furthermore, the plastic flow response of this material is described by a deformation constitutive equation incorporating the effects of temperature, strain rate, strain and work hardening rate. The simulated results based on this constitutive equation are verified. The fracture behaviour and variations of adiabatic shear band produced by deformation at each test condition are investigated with optical microscopy and scanning electron microscopy. The results show that the flow stress of Ti–6Al–4V alloy is sensitive to both temperature and strain rate. Nevertheless, the effect on flow stress of temperature is greater than that of strain rate. Fracture observations reveal that adiabatic shear banding turns out to be the major fracture mode when the material is deformed to large plastic strain at high temperature and high strain rate.

An automatic diagnostic system for CT liver image classification

Abstract: Computed tomography (CT) images have been widely used for liver disease diagnosis. Designing and developing computer-assisted image processing techniques to help doctors improve their diagnosis has received considerable interests over the past years. In this paper, a CT liver image diagnostic classification system is presented which will automatically find, extract the CT liver boundary and further classify liver diseases. The system comprises a detect-before-extract (DBE) system which automatically finds the liver boundary and a neural network liver classifier which uses specially designed feature descriptors to distinguish normal liver, two types of liver tumors, hepatoma and hemageoma. The DBE system applies the concept of the normalized fractional Brownian motion model to find an initial liver boundary and then uses a deformable contour model to precisely delineate the liver boundary. The neural network is included to classify liver tumors into hepatoma and hemageoma. It is implemented by a modified probabilistic neural network (PNN) [MPNN] in conjunction with feature descriptors which are generated by fractal feature information and the gray-level co-occurrence matrix. The proposed system was evaluated by 30 liver cases and shown to be efficient and very effective.

Using a single input to support multiple scan chains

Abstract: Single scan chain architectures suffer from long test application time, while multiple scan chain architectures require large pin overhead and are not supported by boundary scan. We present a novel method to allow a single input line to support multiple scan chains. By appropriately connecting the inputs of all circuits under test during ATPG process such that the generated test patterns can be broadcast to all scan chains when actual testing is executed, we show that 177 and 280 test patterns are enough to detect all detectable faults in all 10 ISCAS'85 combinational circuits and 10 largest ISCAS'89 sequential circuits, respectively.

Universal primers for amplification and sequencing a noncoding spacer between the atpB and rbcL genes of chloroplast DNA

Abstract: Universal primers for amplifying and sequencing a noncoding spacer between the atpB and rbcL genes of the chloroplast DNA were constructed from the published sequences of Marchantia (a liverwort), tobacco, and rice. Our results indicate an evolutionary trend of increasing spacer size from liverworts, through mosses, to vascular plants. This atpB-rbcL spacer is AT-rich, consistent with other chloroplast noncoding spacers. Due to weak functional constraints, the spacer is evolving rapidly. A sequence identity of 92.2% was observed between spacers of two closely related moss species, Rhytidiadelphus loreus and R. triquestrus. Insertion/deletion events are common in the evolution of this spacer. A 23 bp deletion occurrs in R. loreus. Variation is found between two populations of Amorphophallus henryi (Araceae) and between individuals in a populations of Pasania formosana (Fagaceae). We suggest that this spacer will be useful for molecular systematics at the subspecific, specific, and generic levels and, in some species, for population genetics studies.

Indentation Resilience of Conventional and Auxetic Foams

Abstract: Materials with a negative Poisson's ratio (auxetic materials) demonstrate the fascinating property of becoming fatter when stretched. This phenomenon is fundamentally important to the properties of a material and a significant change in the value of the ratio has significant effects on the material's mechanical performance. This article describes foams with a negative Poisson's ratio that show better indentation resilience than conventional foams with a positive Poisson's ratio. The unusual mechanical properties of auxetic foams are attributed to the deformation characteristics of re-entrant (concave polyhedral) cell structures.

Complications in Patients with Palmar Hyperhidrosis Treated with Transthoracic Endoscopic Sympathectomy

Abstract: OBJECTIVE To assess the complications in a group of patients with palmar hyperhidrosis treated with transthoracic endoscopic sympathectomy. The extraordinarily high incidence of postoperative compensatory hyperhidrosis in our series is stressed and explained. METHODS The retrospective study included chart reviews and outpatient assessments. Seventy-two patients underwent T2 or T2-T3 endoscopic sympathectomy for primary palmar hyperhidrosis. Patients' hyperhidrosis severity, precipitating factors, postoperative complications, surgical results, and satisfaction were assessed. Severity of palmar hyperhidrosis and compensatory hyperhidrosis was classified by two grading scales. RESULTS The success rate of sympathectomy was 93%. All patients except one suffered from compensatory sweating, which was the main cause of patients' dissatisfaction postoperatively. Seventeen percent of the patients (12 of 72 patients) experienced new symptoms of gustatory sweating (facial sweating associated with eating). Twenty-one patients experienced other complications, including pneumothorax, Horner's syndrome, nasal obstruction, and intercostal neuralgia. CONCLUSION Transthoracic endoscopic sympathectomy is an effective and simple modality to treat palmar hyperhidrosis. However, all patients need to be warned of the common complications, particularly compensatory hyperhidrosis, before surgery.

Inhibitory Effect of Pulmonary Surfactant Proteins A and D on Allergen-induced Lymphocyte Proliferation and Histamine Release in Children with Asthma

Abstract: The role of pulmonary surfactant proteins in the pathogenesis of airway inflammation and the impact on asthma has not been elucidated. This study was designed to examine the effect of surfactant proteins A (SP-A) and D (SP-D) on phytohemagglutinin- (PHA) and mite allergen Dermatophagoides pteronyssinus (Der p)-induced histamine release and the proliferation of peripheral blood mononuclear cells (PBMC) in children with asthma in stable condition (n = 21), asthmatic children during acute attacks (n = 9), and age-matched control subjects (n = 7). The results show that SP-A and SP-D were able to reduce the incorporation of [3H]thymidine into PBMC in a dose-dependent manner. In addition to the intact, native SP-A and SP-D proteins, a recombinant peptide composed of the neck and carbohydrate recognition domain (CRD) of SP-D [SP-D(N/CRD)] was also found to have the same suppressive effect on lymphocyte proliferation. This effect was abolished by the presence of 100 mM mannose (for SP-A) or maltose (for SP-D) in the culture medium, which suggested that the CRD regions of SP-A and SP-D may interact with the carbohydrate structures on the surface molecules of lymphocytes. The inhibitory effects of surfactant proteins on PHA- and Der p-stimulated lymphocyte responses were observed in stable asthmatic children and age-matched control subjects, while only a mild suppression (< 25%) was seen in activated lymphocytes derived from asthmatic children with acute attacks. SP-A and SP-D were also found to inhibit allergen-induced histamine release, in a dose-dependent manner, in the diluted whole blood of asthmatic children. We conclude that both SP-A and SP-D can inhibit histamine release in the early phase of allergen provocation and suppress lymphocyte proliferation in the late phase of bronchial inflammation, the two essential steps in the development of asthmatic symptoms. It appears that SP-A and SP-D may be protective against the pathogenesis of asthma.

Thermogravimetric studies on the kinetics of rice hull pyrolysis and the influence of water treatment

Abstract: Rice hulls were pyrolyzed in a thermogravimetric analyzer in a helium atmosphere to determine the kinetic parameters of devolatilization reactions. The pyrolysis experiments were conducted by heating rice hulls from room temperature to 1173 K at constant heating rates of 3,10, 30, 60, and 100 K/min. The global mass loss during rice hull pyrolysis was successfully simulated by a combination of four independent parallel reactions, the decompositions of four major components in rice hulls: moisture, hemicellulose, cellulose, and lignin. The activation energy for the decomposition of the nonmoisture components was in the order cellulose > hemicellulose > lignin. It was also found in the present study that the pyrolytic behaviors were significantly influenced by water wash prior to pyrolysis. The water wash elevates the peak temperature and the activation energy for the decomposition of each component of rice hulls. The volatile yields resulting from cellulose and hemicellulose decompositions during rice hull...

Nonlinear H∞ Robust Guidance Law for Homing Missiles

Abstract: This paper proposes an H1 robust guidance law for homing missiles with nonlinear kinematics in the homing phase. Unlike conventional approaches where target’ s acceleration is often assumed to be known or needs to be estimated in real time, the proposed robust guidance law can achieve performance robustness in the absence of target’ s acceleration information and under variations of the initial conditions of engagement. The most dife cult and challenging task involved in applying nonlinear H1 control theory is the solution of theassociated Hamilton ‐ Jacobipartial differentialinequality.In thispaperweshowthattheHamilton ‐Jacobipartialdifferential inequality of the missile guidance problem can be solved analytically with simple manipulations. The numerical simulations show that the H1 robust guidance law exhibits strong robustness properties against disturbances from target’ s maneuvers and variations in initial engagement conditions.

Effects of thermal annealing on the indium tin oxide Schottky contacts of n-GaN

Abstract: In this work indium tin oxide (ITO) films were prepared using electron beam evaporation to form Schottky contacts on n-type GaN films. The thermal stability of ITO on n-type GaN was also investigated by annealing the samples at various temperatures. In addition, current–voltage (I–V) measurements were taken to deduce the Schottky barrier heights. Owing to the large series resistance, the Norde method was used to plot the F(V)–V curves and the effective Schottky barrier heights were determined as well. The effective Schottky barrier heights were 0.68, 0.88, 0.94, and 0.95 eV for nonannealed, 400, 500, and 600 °C annealed samples, respectively. Results presented herein indicate that an increase of the barrier heights may be attributed to the formation of an interfacial layer at the ITO/GaN interface after annealing.

Adaptive Synchronization of Two Lorenz Systemsfn1

Abstract: This paper treats the synchronization problem of two Lorenz systems in the presence of unknown system parameters. Based on the Lyapunov stability theory, an adaptive control law is derived such that the two Lorenz systems are to be synchronized. A robust adaptive control law is also presented to guarantee the robustness of the synchronization against a bounded disturbance. Simulation results are given to demonstrate the effectiveness and robustness of the proposed control schemes.

Detecting Balance Deficits in Frequent Fallers Using Clinical and Quantitative Evaluation Tools

Abstract: OBJECTIVE: This investigation sought to determine whether older idiopathic frequent fallers could be distinguished from healthy older adults on the basis of balance and movement coordination tests A secondary objective was to determine the relationships among clinical balance test scores, balance performance data obtained by accelerometry, and quantitative motor coordination tests DESIGN: Two group comparison designs SETTING: A motor control research laboratory in a university setting PARTICIPANTS: The 16 subjects recruited for this study included eight healthy older subjects and eight age-matched idiopathic fallers MEASUREMENTS: Each participant's balance performance was assessed by accelerometry, as well as by coordination and clinical tests Accelerometry scores, obtained by 1g accelerometers placed at the hip and on the head, were made with eyes open or closed, either standing on the floor or on a wedge of compliant foam Clinical balance scores were obtained using variants of Romberg's test and the functional reach test Motor coordination tests obtained included the heel-to-toe transition and rapid stepping tests MAIN RESULTS: Statistically significant differences were obtained between groups for all accelerometry variables except root mean square All accelerometry variables were successful in discriminating between head and hip sites Moreover, the amplitude of sway obtained from accelerometry data identified significant differences among the four test conditions The Romberg test, using right leg alone with eyes open, showed a significant difference between fallers and healthy older subjects Walking velocity was significantly faster for normal older subjects than for fallers (110 m/sec vs 080 m/sec) No significant between-group differences were obtained using the functional reach test Coordination skills yielded significant between-group differences using the rapid stepping test but no significant differences between groups with the heel-toe transition test CONCLUSION: Accelerometry is an inexpensive and clinically useful technique that can distinguish between healthy older people and idiopathic frequent fallers In conjunction with clinical procedures and commercially available tests to assess motor coordination, these techniques can identify older individuals susceptible to frequent falls

Influence of surface characteristics on liquid-phase adsorption of phenol by activated carbons prepared from bituminous coal

Abstract: Liquid-phase adsorption of phenol by activated carbons prepared from a bituminous coal was investigated. The carbon preparation consisted of carbonization of the oxidized or the unoxidized coal followed by activation in CO2 to various extents of burnoff. It was observed from the experimental results that BET surface area and pore volume are important factors in determining the adsorptive capacity of the activated carbons. The Langmuir model yields a fairly good fit to the adsorption isotherms, indicating a monolayer adsorption of phenol onto these carbons. The amount of phenol adsorbed per unit surface area, corresponding to complete coverage of the adsorptive sites, decreases with the extent of burnoff and with the particle size of the carbon. The decrease can be attributed to the increase in diffusion path. It was found that the adsorptive capacity decreases with the temperature for the carbon prepared from the unoxidized coal, while it increases for the carbons from the oxidized coal. This difference c...

Infections Due to Non-O1 Vibrio cholerae in Southern Taiwan: Predominance in Cirrhotic Patients

Abstract: Although Taiwan is not an area where cholera is endemic, from October 1988 to October 1997 30 episodes of non-Ol, non-O139 Vibrio cholerae infection were noted at the National Cheng Kung University Hospital in Taiwan. Infections generally occurred in hot seasons, and two episodes were concomitant with Vibrio vulnificus infection. Three major clinical presentations were found: bacteremia with concurrent spontaneous bacterial peritonitis or invasive soft-tissue infections that occurred solely in cirrhotic patients; self-limited acute febrile gastroenteritis that occurred in patients with no underlying medical disease; and necrotizing fasciitis or cellulitis that often resulted from a wound on extremities. Other manifestations included fatal pneumonitis in a drowned man and acute pyosalpinx. The differential diagnosis of invasive infections in cirrhotic patients should include infections due to non-Ol V. cholerae or V. vulnificus, and a third-generation cephalosporin and a tetracycline analogue or a fluoroquinolone alone is recommended for treatment of severe vibrio infections.

Role of streptococcal pyrogenic exotoxin B in the mouse model of group A streptococcal infection.

Abstract: Streptococcal pyrogenic exotoxin B (SPE B) is a cysteine protease produced by Streptococcus pyogenes. In this study, the differences in virulence between protease-positive clinical isolates and their protease-negative mutants were examined in a mouse model. Isogenic protease-negative mutants were constructed by homologous recombination, using integrational plasmids to disrupt the speB gene. These mutants caused less mortality and tissue damage than protease-positive strains when inoculated into BALB/c mice via air pouch, suggesting that SPE B cysteine protease plays an important role in the pathogenesis of S. pyogenes infection. Reconstitution of SPE B in the air pouches increased the mortality of mice receiving the speB mutant strain. Infiltrated cell numbers in the exudates from the air pouches of mice infected with SPE B-producing S. pyogenes were higher than those from mice infected with protease-negative mutants at 12 h. However, despite pretreatment with vinblastine to deplete neutrophils, injection of protease-positive bacteria still resulted in severe tissue injury, indicating that neutrophil infiltration may not be the major factor involved in SPE B-enhanced tissue damage. The role of SPE B was further confirmed by demonstrating that SPE B immunization of mice conferred protection from challenge with a lethal dose of protease-positive bacteria.

Efficacy of nasal intermittent positive pressure ventilation in treating apnea of prematurity

Abstract: The efficacy of nasal intermittent positive pressure ventilation (NIPPV) in treating apnea of prematurity was evaluated. Apneic preterm infants were randomly assigned to receive either NIPPV or continuous positive airway pressure (NCPAP) for 4 hr when they failed to respond to conservative therapy. The amount of reduction in apneic spells and bradycardia in the two groups after treatment was compared. Thirty-four infants (18 with NIPPV, 16 with NCPAP) were enrolled. Their birth weights ranged from 590–1,880 g (mean, 1,021 g) and gestational ages from 25–32 weeks (mean, 27.6 weeks). The baseline characteristics were comparable in the two groups. Frequency of apnea and bradycardia was reduced during both forms of treatments. However, the infants receiving NIPPV had a greater reduction of apneic spells (P = 0.02) and a tendency to greater decrease in bradycardia (P = 0.09) than those receiving NCPAP. We conclude that NIPPV is more effective than NCPAP in reducing apnea in preterm infants. NIPPV may reduce bradycardia; however, this needs to be validated by a larger number of observations. Pediatr Pulmonol. 1998; 26:349–353. © 1998 Wiley-Liss, Inc.

Serotonin depresses excitatory synaptic transmission and depolarization‐evoked Ca2+ influx in rat basolateral amygdala via 5‐HT1A receptors

Abstract: The actions of serotonin on rat basolateral amygdala neurons were studied with conventional intracellular recording techniques and fura-2 fluorimetric recordings. Bath application of 5-hydroxytryptamine (5-HT or serotonin) reversibly suppressed the excitatory postsynaptic potential in a concentration-dependent manner without affecting the resting membrane potential and neuronal input resistance. Extracellular Ba2+ or pertussis toxin pretreatment did not affect the depressing effect of 5-HT suggesting that it is not mediated through activation of Gi/o protein-coupled K+ conductance. The sensitivity of postsynaptic neurons to glutamate receptor agonist was unaltered by the 5-HT pretreatment. In addition, the magnitude of paired-pulse facilitation was increased in the presence of 5-HT indicating a presynaptic mode of action. The effect of 5-HT was mimicked by the selective 5-HT1A agonist 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) and was blocked by the selective 5-HT1A antagonist 1-(2-methoxyphenyl)-4[4-(2-phthalimido)butyl]piperazine oxadiazol-3-yl]methyl]phenyl]-methanesulphonamide. In contrast, the selective 5-HT2 receptor antagonist ketanserin failed to affect the action of 5-HT. The effects of 5-HT and 8-OH-DPAT on the high K+-induced increase in [Ca2+]i were studied in acutely dissociated basolateral amygdala neurons. High K+-induced increase in [Ca2+]i was blocked by Ca2+-free solution and Cd2+ suggesting that Ca2+ entry responsible for the depolarization-evoked increase in [Ca2+]i occurred through voltage-dependent Ca2+ channels. Application of 5-HT and 8-OH-DPAT reduced the K+-induced Ca2+ influx in a concentration-dependent manner. The effect of 5-HT was completely abolished in slices pretreated with Rp-cyclic adenosine 3',5'-monophosphothioate (Rp-cAMP), a regulatory site antagonist of protein kinase A, suggesting that 5-HT may act through a cAMP-dependent mechanism. Taken together, these results suggest that functional 5-HT1A receptors are present in the excitatory terminals and mediate the 5-HT inhibition of synaptic transmission in the amygdala.

Solution of two-point boundary-value problems using the differential transformation method

Abstract: This paper considers two-point boundary-value problems using the differential transformation method. An iterative procedure is proposed for both the linear and nonlinear cases. Using the proposed approach, an analytic solution of the two-point boundary-value problem, represented by an mth-order Taylor series expansion, can be obtained throughout the prescribed range.