Sliding mode controller with modified sliding function for DC-DC Buck Converter.

This article presents design of Sliding Mode Controller with proportional integral type sliding function for DC-DC Buck Converter for the controlled power supply. The converter with conventional sliding mode controller results in a steady state error in load voltage. The proposed modified sliding function improves the steady state and dynamic performance of the Convertor and facilitates better choices of controller tuning parameters. The conditions for existence of sliding modes for proposed control scheme are derived. The stability of the closed loop system with proposed sliding mode control is proved and improvement in steady state performance is exemplified. The idea of adaptive tuning for the proposed controller to compensate load variations is outlined. The comparative study of conventional and proposed control strategy is presented. The efficacy of the proposed strategy is endowed by the simulation and experimental results.

Interactions between SERPINA1 PiMZ genotype, occupational exposure and lung function decline.

OBJECTIVES: We evaluated interactions between SERPINA1 PiMZ genotype, associated with intermediate α1-antitrysin deficiency, with outdoor particulate matter ≤10 µm (PM10), and occupational exposure to vapours, dusts, gases and fumes (VGDF), and their effects on annual change in lung function. METHODS: Pre-bronchodilator spirometry was performed in 3739 adults of the Swiss Cohort Study on Air Pollution and Lung Disease in Adults (SAPALDIA) for whom SERPINA1 genotypes were available. At baseline in 1991, participants were aged 18-62 years; follow-up measurements were conducted from 2001 to 2003. In linear mixed regression models of annual change in lung function, multiplicative interactions were evaluated between PiMZ genotype (PiMM as reference) and change in PM10 (µg/m(3)), and VGDF exposure (high-level, low-level or no exposure as reference) during follow-up. RESULTS: Annual declines in forced expiratory flow at 25-75% of forced vital capacity (FEF25-75%) (-82 mL/s, 95% CI -125 to -39) and forced expiratory volume in 1 s over forced vital capacity (FEV1/FVC) (-0.3%, 95% CI -0.6% to 0.0%) in association with VGDF exposure were observed only in PiMZ carriers (Pinteraction<0.0001 and Pinteraction=0.03, respectively). A three-way interaction between PiMZ genotype, smoking and VGDF exposure was identified such that VGDF-associated FEF25-75% decline was observed only in ever smoking PiMZ carriers (Pinteraction=0.01). No interactions were identified between PiMZ genotype and outdoor PM10. CONCLUSIONS: SERPINA1 PiMZ genotype, in combination with smoking, modified the association between occupational VGDF exposure and longitudinal change in lung function, suggesting that interactions between these factors are relevant for lung function decline. These novel findings warrant replication in larger studies.

Cotton dust, endotoxin and cancer mortality among the Shanghai textile workers cohort: a 30-year analysis.

BACKGROUND: Although occupational exposure to cotton dust and endotoxin is associated with adverse respiratory health, associations with cancer are unclear. We investigated cancer mortality in relation to cotton dust and endotoxin exposure in the Shanghai textile workers cohort. METHODS: We followed 444 cotton textile and a reference group of 467 unexposed silk workers for 30 years (26 777 person-years). HRs for all cancers combined (with and without lung cancer) and gastrointestinal cancer were estimated in Cox regression models as functions of cotton textile work and categories of cumulative exposure (low, medium, high), after adjustment for covariates including pack-years smoked. Different lag years accounted for disease latency. RESULTS: Risks of mortality from gastrointestinal cancers and all cancers combined, with the exclusion of lung cancer, were increased in cotton workers relative to silk workers. When stratified by category of cumulative cotton exposure, in general, risks were greatest for 20-year lagged medium exposure (all cancers HR=2.7 (95% CI 1.4 to 5.2); cancer excluding lung cancer HR=3.4 (1.7-7.0); gastrointestinal cancer HR=4.1 (1.8-9.7)). With the exclusion of lung cancer, risks of cancer were more pronounced. When stratified by category of cumulative endotoxin exposure, consistent associations were not observed for all cancers combined. However, excluding lung cancer, medium endotoxin exposure was associated with all cancers and gastrointestinal cancer in almost all lag models. CONCLUSIONS: Cotton dust may be associated with cancer mortality, especially gastrointestinal cancer, and endotoxin may play a causative role. Findings also indirectly support a protective effect of endotoxin on lung cancer.

Acute respiratory health effects of urban air pollutants in adults with different patterns of underlying respiratory disease.

OBJECTIVE: Whether underlying chronic respiratory diseases are susceptible factors for symptomatic episodes, which lead to primary-level care, in association with air pollutant exposures is unknown. We evaluated and compared association lag structures between daily ambient levels of nitrogen dioxide (NO(2)) and total suspended particulates (TSP) and respiratory symptom-related doctor visits in adults with different patterns of underlying chronic respiratory disease. METHODS: In a time-stratified case-crossover analysis nested within a diary panel study, 459 Swiss adult participants with asthma, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and healthy participants recorded occurrence of respiratory-symptom related doctor visits (n = 1,048) in one to six four-week intervals over two years. For each disease subgroup, odds ratios (ORs) for doctor visit were estimated as a function of NO(2) or TSP concentrations (per 10 micrograms per cubic meter [µg/m(3)]) lagged between 0-13 days in a polynomial distributed lag model. RESULTS: Higher ORs for NO(2) in participants with COPD (OR: 1.17, 95%CI: 1.02-1.35) and asthma (OR: 1.15, 95%CI: 1.02-1.30) occurred at exposure lags of two and five days, respectively. Doctor visits increased by 9.1% (95%CI: 3.2-15.4%) and 4.2% (95%CI: 1.2-7.2%) over the first week following a 10 µg/m(3) increase in NO(2) concentration in the COPD and chronic bronchitis subgroups, respectively. The percent increase in the COPD subgroup was significantly greater (p <0.05) when compared with the healthy subgroup. Observed findings were similar for TSP. CONCLUSIONS: Respiratory problems leading to a doctor visit, associated with an increase in exposure to NO(2) and TSP, may have a faster dynamic in individuals with COPD.

Genetic susceptibility to occupational exposures.

Because of their high prevalence in the general population, genetic variants that determine susceptibility to environmental exposures may contribute greatly to the development of occupational diseases in the setting of specific exposures occurring in the workplace. Studies investigating genetic susceptibilities in the workplace may: (1) provide mechanistic insight into the aetiology of disease, in particular the determination of environmentally responsive genes; (2) identify susceptible subpopulations with respect to exposure; and (3) provide valuable input in setting occupational exposure limits by taking genetic susceptibility into account. Polymorphisms in the NAT2 and the HLA-DPB1(G)(lu69) genes provide classic examples of how genetic susceptibility markers have a clear role in identifying disease risk in bladder cancer and chronic beryllium disease, respectively. For diseases with more complex and multifactorial aetiology such as occupational asthma and chronic airways disease, susceptibility studies for selected genetic polymorphisms provide additional insight into the biological mechanisms of disease. Even when polymorphisms for genetic susceptibility have a clear role in identifying disease risk, the value of wide scale genetic screening in occupational settings remains limited due to primarily ethical and social concerns. Thus, large scale genetic screening in the workplace is not currently recommended.

Work area measurements as predictors of personal exposure to endotoxin and cotton dust in the cotton textile industry.

OBJECTIVES: To determine if work area measurements of endotoxin and/or cotton dust obtained from the vertical elutriator (VE) can be used to predict levels of personal endotoxin exposure as measured by the Institute of Occupational Medicine (IOM) inhalable dust sampler in the cotton textile industry. METHODS: Fifty-six work area cotton dust samples were collected from 14 areas and 82 personal cotton dust samples were collected from 41 workers in three textile mills (Mills A, B and C) in Shanghai, China. Cotton dust concentrations were determined gravimetrically from sample filters, of which endotoxin concentrations were determined using a kinetic chromogenic modification of the limulus amoebocyte lysate assay. Linear regression models were used to determine the association between log IOM personal endotoxin concentration and log VE area endotoxin concentration. RESULTS: Median cotton dust and endotoxin concentrations measured from VE area samples in the three mills were 0.36 mg m(-3) and 1280.76 endotoxin units per cubic meter (EU m(-3)), respectively, compared to 1.74 mg m(-3) and 2226.83 EU m(-3) from IOM personal samples. Excluding samples from weaving processes, we observed linear associations between VE area measures of endotoxin and IOM personal endotoxin concentrations; VE area concentration of endotoxin explained 83 and 89% of the total variation in IOM personal endotoxin concentration for Mills A and B, respectively (Mill A: R2 = 0.83, P < 0.0001; Mill B: R2 = 0.89, P < 0.0001). Although area measures of cotton dust was also a significant predictor of person endotoxin, the model explained less of the variance in personal endotoxin measurements. CONCLUSIONS: Specific to the conditions of the textile mills investigated in this study, work area measurements of endotoxin, but not cotton dust, may be reasonable proxies for personal levels, at least for rank-ordering exposures.

Airflow limitation and changes in pulmonary function among bleachery workers.

This study investigated whether chronic airflow limitation and rapid decline in pulmonary function were associated with peak exposures to ozone and other irritant gases in pulp mills. Bleachery workers potentially exposed to irritant gassings (n = 178) from three Swedish pulp mills, and a comparison group of workers not exposed to irritant gassings (n = 54) from two paper mills, were studied. Baseline surveys occurred in 1995-1996, with follow-up surveys in 1998-1999. Participants performed spirometry and answered questions regarding ozone, chlorine dioxide (ClO2), and sulphur dioxide (SO2) gassings. From regression models controlling for potential confounders, declines in both the forced expiratory volume in one second (FEV1) (-24 mL x yr(-1)) and the forced vital capacity (FVC) (-19 mL x yr(-1)) were associated with ClO2/SO2 gassings. At follow-up, the prevalence of chronic airflow limitation (i.e. FEV1/FVC less than the lower limit of normal) was elevated for participants with only pre-baseline ozone gassings and with both pre-baseline and interval ozone gassings, after controlling for potential confounders. These findings suggest that obstructive effects among bleachery workers are associated with ozone gassings, and that adverse effects on spirometry might also accompany chlorine dioxide/sulphur dioxide gassings. Peak exposures to irritant gases in pulp mills should be prevented.

Mitotic Golgi is in a dynamic equilibrium between clustered and free vesicles independent of the ER.

Golgi inheritance during cell division involves Golgi disassembly but it remains unclear whether the breakdown product is dispersed vesicles, clusters of vesicles or a fused ER/Golgi network. Evidence against the fused ER/Golgi hypothesis was previously obtained from subcellular fractionation studies, but left concerns about the means used to obtain and disrupt mitotic cells. Here, we performed velocity gradient analysis on otherwise untreated cells shaken from plates 9 h after release from an S-phase block. In addition, we used digitonin and freeze/thaw permeabilization as alternatives to mechanical homogenization. Under each of these conditions, approximately 75% of the Golgi was recovered in a population of small vesicles that lacked detectable ER. We also used multilabel fluorescent microscopy with optical sectioning by deconvolution to compare the 3D metaphase staining pattern of endogenous Golgi and ER markers. Although both ER and Golgi staining were primarily diffuse, only the ER was excluded from the mitotic spindle region. Surprisingly, only 2% of the Golgi fluorescence was present as resolvable structures previously characterized as vesicle clusters. These were not present in the ER pattern. Significantly, a portion of the diffuse Golgi fluorescence, presumably representing dispersed 60-nm vesicles, underwent an apparent rapid aggregation with the larger Golgi structures upon treatments that impaired microtubule integrity. Therefore, mitotic Golgi appears to be in a dynamic equilibrium between clustered and free vesicles, and accurate partitioning may be facilitated by microtubule-based motors acting on the clusters to insure random and uniform distribution of the vesicles.

Gastro-oesophageal reflux in patients with coronary artery disease: how common is it and does it matter?

OBJECTIVE: To investigate the influence of spontaneous gastro-oesophageal reflux (GOR) on symptoms and cardiac ischaemia in patients with coronary artery disease. DESIGN: Simultaneous 24-h ambulatory oesophageal pH, 7-lead electrocardiographic (ECG) monitoring and symptom diary in patients taking their usual anti-anginal medication. SETTING: Regional cardiothoracic unit and gastroenterology unit of a teaching hospital. SUBJECTS: Twenty-four patients (20 males, 4 females, mean age 59 years) with post-myocardial infarction angina and angiographically proven coronary artery disease. MAIN OUTCOME MEASURES: Quantitation of acid gastro-oesophageal reflux (% total time pH < 4, number of reflux episodes, duration of reflux episodes), identification of ST segment elevation or depression of 1 mm or more on 24-h ECG recording and occurrence of chest pain ("heartburn' or "angina') within 5 min of GOR or ischaemic ST segment shift. RESULTS: There were 568 episodes of GOR, 28 of which were symptomatic. Abnormal GOR (% total time pH < 4 greater than 7%) occurred in 9 (38%) of the patients; all reflux parameters were increased in nitrate users compared to non-users (P < 0.05). Ischaemic ST-segment shift was seen on 113 occasions. Of a total of 41 chest pain episodes, 20 were related to GOR ("angina' with 8, "heartburn' with 12), while 8 coincided with both GOR and ST depression together ("angina' in 5, "heartburn' in 3). In addition to these eight episodes, coincidence of ST depression with GOR occurred on another nine occasions (all asymptomatic). CONCLUSION: GOR is common in patients with coronary artery disease and may be increased by drug therapy; GOR may occasionally be associated with myocardial ischaemia, but this is uncommonly symptomatic; GOR-induced pain is sometimes mistaken for angina. These effects were uncommon overall, but frequent in a few individuals and should be considered in the evaluation of patients with persistent chest pain despite seemingly adequate antianginal treatment.

Sensitization to painful distention and abnormal sensory perception in the esophagus.

BACKGROUND/AIMS: The mechanism of abnormal esophageal sensory perception in patients with unexplained chest pain is unknown. The aim of this study was to test the following two hypotheses: (1) similar to cutaneous nociceptors, esophageal stretch receptors can be sensitized by a noxious chemical stimulus, and (2) patients with esophageal chest pain have sensitized receptors. METHODS: Twenty-five patients with noncardiac chest pain underwent esophageal manometry, provocation tests, and 24-hour pH monitoring. Eleven patients had positive and 14 had negative results of esophageal provocation tests. Esophageal perception and pain thresholds for balloon stretch (in milliliters) and electrical stimulation (in milliamperes) were determined in patients and 7 healthy controls performed before and after randomized, double-blind esophageal perfusion with normal saline or 0.1N HCl. RESULTS: The basal balloon pain threshold was lower in patients with positive results of esophageal tests than in either those patients with negative results of esophageal tests or controls (P < 0.05). After acid perfusion, balloon perception and pain thresholds decreased in patients with negative results of esophageal tests (P < 0.05) and in controls (P < 0.05) but not in patients with positive results of esophageal tests. No change occurred after saline perfusion nor in electrical pain thresholds in any group after the perfusion of either fluid. CONCLUSIONS: In patients with negative results of esophageal tests and in controls, the pain threshold to balloon distention is lowered by acid. The lack of such effect in patients with positive results of esophageal tests implies that pain receptors may already be sensitized.

Rehabilitation of fractures in the elderly.

Rehabilitation is the most important aspect of care after a fracture in an older person. Epidemiology, contributing factors, general principles of management are discussed in this article. Proper management requires knowledge of various mechanisms of injury, different forms of orthopedic treatments, interpretation of radiographs, and familiarity with available therapeutic modalities.

Shoulder pain in hemiplegia. The role of exercise.

One of the causes for shoulder pain associated with hemiplegia is thought to be vigorous range of motion to the involved upper extremity. The objective of this study was to analyze the occurrence of pain in patients treated with one of the three exercise programs commonly used in the rehabilitation of hemiplegia: 1) range of motion by the therapist, 2) skate board and 3) overhead pulley. Of the 48 hemiplegic patients evaluated, 28 were assigned to one of the three exercise groups. Comparing the number of patients who developed pain in each group, there was a significant difference, with 8% of the patients in the range of motion by the therapist group, 12% of the patients in the skate board group and 62% of the patients in the overhead pulley group developing pain (chi 2 = 8.44) (P = 0.014). The three groups did not differ in the side of involvement (P = 0.57), extent of hemiplegia (P = 0.25) or presence of subluxation (P = 0.84). Use of overhead pulley has the highest risk of developing shoulder pain and should be avoided during rehabilitation of stroke patients.

Peripheral nerve conduction studies and bulbocavernosus reflex in the investigation of impotence.

Patients with erectile dysfunction underwent sensory and motor conduction and bulbocavernosus reflex tests to determine the incidence of peripheral nerve involvement. Of a total of 111 patients, abnormal sensory conduction was found in 87 (78%), abnormal motor conduction in 56 (50%), and abnormal bulbocavernosus reflex in 40 (36%). Most of these patients had other medical problems. Objective evidence of peripheral nerve involvement helped in the management of these patients.

Evaluation of impotence in older men.

Careful evaluation was carried out in 93 men older than 50 with erectile dysfunction. Their mean age was 61 years and the disorder had been present for a mean of 4.5 years. While 14 men (15%) had psychosocial factors that may have been pertinent, only 2 scored poorly on an Affect Balance Scale and 3 were receiving psychoactive medications. Results of nocturnal penile tumescence were abnormal in 91%. In 39% penile-brachial pressure indices were suggestive of pelvic vascular disease and in 9% were consistent with a pelvic "steal syndrome." Pelvic or peripheral nerve conduction disorders were also commonly seen in 54%. Endocrinopathy may have contributed to the dysfunction in 35%. Twenty-one men had diabetes mellitus, two new cases of hypothyroidism were discovered and hypogonadism was diagnosed definitely in four and considered likely in five others. Coexisting medical conditions were found in more than 90% of the men, especially hypertension, use of antihypertensive medications and atherosclerotic disease. Previous prostatectomies (19%) and vasectomies (30%) were common in the surgical histories. Given the wide range of disorders uncovered in older men complaining of impotence, diagnostic study of potential causes may lead to a more rational approach for the evaluation and management of these men.

Outpatient rehabilitation center keeps many elderly living at home.

A geriatric day hospital in Scotland provides community residents with transportation to and from their homes for therapeutic treatment.

Orbicularis oculi reflex in brain death.

The early and late components of the orbicularis oculi reflex were absent bilaterally in three patients who fulfilled the clinical and electroencephalographic criteria of brain death. A response to peripheral facial nerve stimulation was obtained in all. These preliminary observations suggest that the study of the orbicularis oculi reflex is a simple, objective, bedside neurophysiological test of brain stem function, complementing the electroencephalogram in the diagnosis of brain death.