Design of uncertain displacement controlled velocity control system for hydraulic actuator.

Displacement-controlled systems have high efficiency and are widely used in industry. Accurate control of the actuator motion in hydraulic systems is usually a necessity in industrial applications such as the motion of control surfaces in fixed-wing airplanes for flight control as well as the aircraft brake systems. To address this need, the current study was conducted with the goal of developing a high-fidelity model to achieve precise control. This work focused on modeling a hydrostatic transmission that is used for controlling a linear actuator velocity. The flow entering the actuator was changed using a variable displacement pump. The study included examining the stability and performance of the open-loop system. Additionally, the study involved the design of the proportional-integral-derivative PID and H∞ controllers, followed by the analysis of the stability and performance of the closed-loop system with both controllers. Furthermore, the multiplicative uncertainty is taken into account and the robustness of the system is verified using controllers PID and H∞. In the current study,Uncertain parameters such as actuator efficiency, pump speed, and viscous friction coefficient were considered and allowed for a ±5% deviation from their stated values. Taking uncertainty into account ensures that the system performs properly even in case where the design parameters vary within the specified range. The system response is compared for the cases of open-loop system, closed-loop system with PID controller, and closed-loop system with H∞ controller. The results demonstrated that the open-loop system remains stable for real-world applications but shows insufficient performance in terms of input tracking and disturbance rejection. The introduction of the PID controller significantly enhanced the system's response to a reference input; however, its disturbance rejection capabilities in terms of overshoot and settling time were still unsatisfactory. The system equipped with the PID controller failed to meet the robustness requirements. Conversely, the utilization of H∞ controllers yielded superior responses and fulfilled the robustness criteria.

The association of FKBP5 polymorphism with asthma susceptibility in asthmatic patients.

OBJECTIVES: Inhaled corticosteroids are the most effective controllers of asthma, although asthmatics vary in their response. FKBP51 is a major component of the glucocorticoid receptor which regulates its responses to corticosteroids. Therefore, the present study aims to identify the role of FKBP5 gene polymorphism in asthma susceptibility and corticosteroid resistance. METHODS: DNA was extracted from the blood of 68 asthmatic and 40 control subjects. FKBP5 gene fragments were amplified by PCR and sequenced by the Sanger method. The sequencing results were aligned by mapping on the reference sequences of National center of Biotechnology Information (NCBI) and single nucleotide polymorphisms (SNPs) which were checked. Finally, the genotype, allele frequency and odds ratio (OR) were calculated. RESULTS: The FKBP5 fragment sequencing revealed the presence of rs1360780 and one novel SNP found in 17 samples taken from asthmatic patients as compared to db SNP data in the NCBI database. The FKBP5 variant (rs1360780) indicated that the allele frequency of risk allele T was 41.18% in patients and 20% in control group members p<0.001 and OR=2.8 when compared to a wild C allele frequency of 58.82% in patients and 64% in the control group members. The novel SNP FKBP5 was compared to the SNP database in the NCBI database in which wild T allele was substituted with G. The novel SNP was submitted to the ClinVar Submission Portal at NCBI with accession number: rs1581842283 and confirmed an asthma susceptibility risk factor with allele G frequency of 11.76% in asthmatics and 2.5% in the control group members (OR=5.2, p<0.05), as compared to a wild T allele frequency of 88.24% in asthmatics and 97.5% in the control group members. CONCLUSIONS: The risk allele T of rs1360780 and the novel SNP rs1581842283 risk allele G predict asthma susceptibility but show no association with corticosteroid resistant.

Surveys of Current Teaching and Practice for Impressions for Complete Dentures.

OBJECTIVES: The 3 objectives are to assess current preferences for impressions for complete dentures, audit practice and compare practice to current UK teaching. METHODS: Three surveys where undertaken; a survey of GDPs preferences, an audit of practice and a survey of teaching in UK dental schools. RESULTS: UK Universities advocate border moulded custom trays. In stated preferences, 99% of practitioners used custom trays for private practice; 67% for NHS work. In actual use, the audit found 91% practitioners in private practice used custom trays; in NHS practice 78% did so. The most widely taught materials were silicone (43%), alginate (29%), & zinc oxide eugenol paste (19%). In practitioners stated preferences, 97% of NHS and 53% of private dentists listed alginate as an option; however the audit showed only 74% (NHS) and 52% (private) actually used alginate, with 20% (NHS) and 48% (private) using silicone. CONCLUSIONS: Definitive impressions in custom trays are used by GDPs for both private and NHS work; they are universally taught at UK dental schools. Alginate is popular in NHS practice; however, silicone is more widely taught in UK Universities. The use of silicone materials for definitive impressions has increased since 1999. In UK private practice silicone usage is aligned in popularity with alginate.

Dedicated asthma center improves the quality of care and resource utilization for pediatric asthma: a multicenter study.

OBJECTIVES: To determine the relative effectiveness of pediatric asthma care among patients treated by a dedicated asthma center (AC) vs children who use the emergency department (ED) as a site of primary asthma care. METHODS: A retrospective case-control design was used. A random sample of AC cases was selected from a designated comprehensive AC over a 12-month period. Concurrent ED control patients were identified from all cases of pediatric asthma from five urban hospitals based on two or more ED visits. Cases and controls were matched (1:2) based on age and National Heart, Lung, and Blood Institute (NHLBI) asthma severity of illness classification. A telephone survey was administered to the caregivers of all enrolled patients in the study sample. RESULTS: Four elements of pediatric asthma care were examined: quality, access, hospital utilization, and functional impact of disease. Demographic data were similar between the ED cases and the AC controls. In terms of quality of care, the AC patients were more likely to use maintenance antiinflammatory medications, 60.2% vs 22.5% (OR = 5.3; 95% CI = 2.9 to 9.7) and more likely to be taking medications at school, 71.4% vs 48.1% (OR = 2.7; 95% CI = 1.5 to 4.7). In terms of access to care, the AC families were more likely to have a physician to call to assist with outpatient management, 98.2% vs 65.0% (OR = 25.3; 95% CI = 9.0 to 76.9). Frequent ED utilization (> or = 1 visit/month) was less likely in the AC patients, 9.2% vs 22.0% (OR = 0.35; 95% CI = 0.16 to 0.79) and school absenteeism was lower as well (9.5 +/- 6.7 days vs 16.6 +/- 10.3, p < 0.001). Additionally, the caregivers of the AC patients missed fewer workdays (4.7 +/- 2.8 vs 7.4 +/- 4.1; p = 0.03). CONCLUSIONS: Significant disparities in quality, access, resource utilization, and functional impact exist between AC and ED patients. Emergency physicians have a unique opportunity to improve the public health by directing ED patients toward pediatric AC treatment.

Persistently negative tuberculin reactions: their presence among children with culture positive for Mycobacterium tuberculosis (tuberculin-negative tuberculosis).

Mantoux tests were performed on 200 children with culture-proven Mycobacterium tuberculosis infections. A group of 28 patients initially had negative reactions to 5 TU PPD-S. Of these, 17 had had extensive or overwhelming tuberculous disease at the time of admission, seven of whom reacted to 250 TU PPD; after a course of chemotherapy, all the survivors had positive reactions to 5 TU PPD-S. The 11 with less severe disease had negative reactions to 5 TU PPD-S and 250 TU PPD, as well as to PPD-A/B/G; in only two could a ready explanation be found for the negative reactor state. In general, a small number of children without life-threatening forms of tuberculosis may have persistently negative tuberculin reactions without any apparent cause. In such cases, other criteria for diagnosis must be relied on, such as lymphocyte transformation, culture, and biopsy.