Controller Design for Unstable Time-Delay Systems with Unknown Transfer Functions

This study developed a method for designing parallel two-degree-of-freedom proportional-integral-derivative controllers for unstable time-delay processes with unknown dynamic equations. First, a performance index accounting for both transient response performance and disturbance rejection was developed. To obtain useful data even if the output of the system exceeds the allowable range, an effective penalty function was included in the performance index. The N–M simplex method was used to iteratively determine the optimal controller parameters. The proposed approach has the following advantages: (1) it can be used regardless of the stability of the open-loop system; (2) the mathematical model and parameters of the process need not be known in advance; (3) it can be used for processes that include measurement noise; (4) it has good transient response performance and is also robust against external disturbances; and (5) it enables more efficient controller design and reduces costs

Controller Design for Unstable Time-Delay Systems with Unknown Transfer Functions

This study developed a method for designing parallel two-degree-of-freedom proportional-integral-derivative controllers for unstable time-delay processes with unknown dynamic equations. First, a performance index accounting for both transient response performance and disturbance rejection was developed. To obtain useful data even if the output of the system exceeds the allowable range, an effective penalty function was included in the performance index. The N–M simplex method was used to iteratively determine the optimal controller parameters. The proposed approach has the following advantages: (1) it can be used regardless of the stability of the open-loop system; (2) the mathematical model and parameters of the process need not be known in advance; (3) it can be used for processes that include measurement noise; (4) it has good transient response performance and is also robust against external disturbances; and (5) it enables more efficient controller design and reduces costs

Diagnostic value of bronchoalveolar lavage in children with nonresponding community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common cause of morbidity and mortality in hospitalized children. In CAP, causative agents are seldom identified using noninvasive diagnostic procedures. For those children not responding to empiric antibiotic therapy, it is vital to identify the causative pathogens for further management. Methods: We aimed to determine the usefulness of identifying the causative agents by bronchoalveolar lavage (BAL) in hospitalized children with nonresponding CAP. Ninety children hospitalized for CAP and treated with empiric antibiotics but having persistent fever ≥48 hours were enrolled, and their BAL data were retrospectively reviewed. Results: Aerobic bacteria were isolated from 38 (42%) of 90 cultures, and anaerobic bacteria were isolated from eight (24%) of 33 cultures. The bacteria isolated most frequently were Streptococcus viridians (26.3%), Pseudomonas aeruginosa (23.7%), and Staphylococcus aureus (15.8%). Streptococcus pneumoniae was isolated from the BALs of only two children, and Haemophilus influenzae from none. For positive aerobic culture results, BAL results guided modifications of antibiotic regimens in 21 episodes (21 of 38, 55.3%). Conclusion: BAL results guided a change of antimicrobials in 55% of children with positive aerobic cultures (29% of all children in the study) and contributed to a high rate of successful therapy

Risk factors for neonatal early-onset group B streptococcus-related diseases after the implementation of a universal screening program in Taiwan

Abstract Background We examined the risk for Group B streptococcus (GBS)-related diseases in newborns born to mothers who participated in a universal GBS screening program and to determine whether differences are observed in factors affecting the morbidity for neonatal early-onset GBS-related diseases. Methods This is a retrospective study and the study subjects were women who had undergone GBS screening and who gave birth naturally and their newborns between April 15, 2012 and December 31, 2013. Data from the GBS screening system database and the National Health Insurance database were collected to calculate the GBS prevalence in pregnant women and morbidity of newborns with early-onset GBS-related diseases. Results The GBS prevalence in pregnant women who gave birth naturally was 19.58%. The rate of early-onset infection caused by GBS in newborns decreased from the original 0.1% to 0.02%, a decrease of as high as 80%. After the implementation of the universal GBS screening program, only three factors, including positive GBS screening result (OR = 2.84), CCI (OR = 2.45), and preterm birth (OR = 4.81) affected the morbidity for neonatal early-onset GBS-related diseases, whereas other factors had no significant impact. Conclusion The implementation of the universal GBS screening program decreased the infection rate of neonatal early-onset GBS diseases. The effects of socioeconomic factors and high-risk pregnancy on early-onset GBS infections were weakened

Parenting stress in parents of children with refractory epilepsy before and after vagus nerve stimulation implantation

Objectives: The purpose of this study was to evaluate parenting stress in parents of children with refractory epilepsy before and after their children received vagus nerve stimulation (VNS) implantation. Methods: Parents of children with refractory epilepsy completed the Parenting Stress Index (PSI) under a psychologist's assessment before and at least 12 months after their children received VNS implantation. The PSI questionnaire measures parenting stress in two domains; a parent domain with seven subscales, and a child domain with six. Age, gender, epilepsy comorbidity, VNS implantation date, seizure frequency, and anticonvulsant history before and after VNS implantation were obtained from reviews of medical charts. Results: In total, 30 parents completed the first and follow-up PSI questionnaires. Seventeen of their children (56.7%) were boys. The children aged from 1 to 12 years (7.43 ± 3.59 years, mean ± SD). After VNS implantation, the mean total parenting stress scores decreased from 282.1 ± 38.0 to 272.4 ± 42.9. A significant decrease was found on the spouse subscale of the parent domain. For the parents of boys, the mean total parenting stress scores decreased significantly. The mean total parenting stress scores also decreased significantly for parents of epileptic children without autism and who did not taper off the number of different anticonvulsants used after VNS. Conclusions: VNS is an advisable choice to treat refractory epilepsy. Our study showed that 12 months or more after VNS implantation, seizure frequency and parenting stress typically decreased. However, in some special cases the parenting stress may increase, and external help may be required to support these patients and their parents. Key Words: children, refractory epilepsy, parenting stress, vagus nerve stimulatio

Imaging Endogenous Bilirubins with Two-Photon Fluorescence of Bilirubin Dimers

On the basis of an infrared femtosecond Cr:forsterite laser, we developed a semiquantitative method to analyze the microscopic distribution of bilirubins. Using 1230 nm femtosecond pulses, we selectively excited the two-photon red fluorescence of bilirubin dimers around 660 nm. Autofluorescences from other endogenous fluorophores were greatly suppressed. Using this distinct fluorescence measure, we found that poorly differentiated hepatocellular carcinoma (HCC) tissues on average showed 3.7 times lower concentration of bilirubins than the corresponding nontumor parts. The corresponding fluorescence lifetime measurements indicated that HCC tissues exhibited a longer lifetime (500 ps) than that of nontumor parts (300 ps). Similarly, oral cancer cell lines had longer lifetimes (>330 ps) than those of nontumor ones (250 ps). We anticipate the developed methods of bilirubin molecular imaging to be useful in diagnosing cancers or studying the dynamics of bilirubin metabolisms in live cells