Sheetu Singh

Cost analysis of a two unit priority standby system with imperfect switch and arbitrary distributions

Abstract This paper deals with cost analysis of a single server two-unit (one priority and the other ordinary) cold standby system with two modes—normal and total failure. A switch is used to operate the standby unit (ordinary) and it works successfully with known probability p( = 1 − q). Priority unit gets preference both for operation and repair. Failure and repair time distributions are arbitrary. System fails when switch or both the units fail totally. The system is observed at suitable regenerative epochs in order to obtain reliability characteristics of interest to system designers and operations managers. Explicit results for the exponential time distributions have been obtained in particular cases.

Cost analysis of a two-unit cold standby system with two types of operation and repair

Abstract This paper deals with the cost analysis of a single-server two-identical unit cold standby system and two types of repair—minor and major. The unit requires minor repair if it fails for the first time. The major repair is required only when the unit fails after the minor repair. Upon minor repair the unit does not work as a normal unit but as a quasi-normal unit which has a different (increased) failure rate from that of a new one. Upon major repair the unit works as good as new (normal unit). Failure time distributions are negative exponential whereas repair time distributions are general. Using regeneration point technique the system characteristics of interest to system designers and operations managers have been obtained.

Interstitial Lung Disease in India. Results of a Prospective Registry

Rationale: Interstitial lung disease (ILD) is a heterogeneous group of acute and chronic inflammatory and fibrotic lung diseases. Existing ILD registries have had variable findings. Little is known about the clinical profile of ILDs in India. Objectives: To characterize new‐onset ILDs in India by creating a prospective ILD using multidisciplinary discussion (MDD) to validate diagnoses. Methods: Adult patients of Indian origin living in India with new‐onset ILD (27 centers, 19 Indian cities, March 2012‐June 2015) without malignancy or infection were included. All had connective tissue disease (CTD) serologies, spirometry, and high‐resolution computed tomography chest. ILD pattern was defined by high‐resolution computed tomography images. Three groups independently made diagnoses after review of clinical data including that from prompted case report forms: local site investigators, ILD experts at the National Data Coordinating Center (NDCC; Jaipur, India) with MDD, and experienced ILD experts at the Center for ILD (CILD; Seattle, WA) with MDD. Cohens &kgr; was used to assess reliability of interobserver agreement. Measurements and Main Results: A total of 1,084 patients were recruited. Final diagnosis: hypersensitivity pneumonitis in 47.3% (n = 513; exposure, 48.1% air coolers), CTD‐ILD in 13.9%, and idiopathic pulmonary fibrosis in 13.7%. Cohens &kgr;: 0.351 site investigator/CILD, 0.519 site investigator/NDCC, and 0.618 NDCC/CILD. Conclusions: Hypersensitivity pneumonitis was the most common new‐onset ILD in India, followed by CTD‐ILD and idiopathic pulmonary fibrosis; diagnoses varied between site investigators and CILD experts, emphasizing the value of MDD in ILD diagnosis. Prompted case report forms including environmental exposures in prospective registries will likely provide further insight into the etiology and management of ILD worldwide.

Profit analysis of a cold standby system with two repair distributions

Abstract A single server two-identical unit cold standby system is analysed. Each unit has two operative modes—normal and quasi-normal. When a normal unit fails, it undergoes minor repair with probability p 1 and p 2 respectively. Upon minor repair unit works with reduced efficiency and is known as quasi-normal unit while upon major repair unit works as good as new (normal unit). When a quasi-normal unit fails, it undergoes minor or major repair with probability q 1 and q 2 respectively. Failure rates of normal and quasi-normal units are different. Failure time distributions are negative exponential whereas repair time distributions are general. Using regeneration point technique in MRP the system characteristics of interest to system designers and operations managers have been obtained.

Effect of Dust Aerosol in Patients with Asthma

Objective. Sandstorms frequently cause adverse health effects especially in patients with asthma. The aim of our research was to explore the mechanism of sandstorm-induced asthmatic exacerbation by administering dust aerosol through an environmentally controlled exposure chamber. Methods. Four samples of soil (Ganganagar clay, Bikaner sand, Jaipur sand, and Ganganagar sand) were collected from three sandstorm-prone areas of Rajasthan, the desert state of India. Twenty patients with asthma, who had stable disease with a forced expiratory volume in first second (FEV1) more than 70% of predicted, volunteered to participate in this randomized single-blind placebo-controlled crossover study. The four samples of dust and placebo were administered randomly on 5 study days. FEV1 was measured for the next 60 minutes and the maximal decline in FEV1 (ΔFEV1) from baseline was measured. The samples of dust were also analyzed for particle size and adhesiveness. Results. The maximal decline in FEV1 was observed 15 minutes post-exposure with all dust samples. Mean ΔFEV1 was 0.69 ± 0.08 liters for Ganganagar clay, 0.52 ± 0.06 liters for Bikaner sand, 0.39 ± 0.07 liters for Jaipur sand, and 0.32 ± 0.04 liters for Ganganagar sand dust aerosol samples. Decline in FEV1 correlated with volume of dust particles with size <10 μm (PM10) and adhesiveness of the dust particles. Conclusion. Smaller-size sandstorm dust particles with higher adhesive properties have a greater potential of aggravating asthma.

A two (multicomponent) unit parallel system with standby and common cause failure

Abstract This paper investigates the mathematical model of a system composed of two non-identical active parallel units and one cold standby. A unit has N components, each having a constant failure and repair rate. These vary from component to component. Several reliability characteristics of interest to system designers as well as operations managers have been computed. Results obtained earlier are verified as particular cases.

Psychiatric morbidity in chronic respiratory disorders in an Indian service using GMHAT/PC.

OBJECTIVE The study aimed to assess psychiatric morbidity in stable chronic respiratory disorders and to examine the pattern of psychiatric illness in specific respiratory disorders in Northern India. METHODS All consecutive patients with stable chronic respiratory illnesses who attended the respiratory disease clinic were recruited in the study. Their healthy attendants were interviewed as a control group. The research clinician, trained in the use of the Global Mental Health Assessment Tool, Primary Care Version (GMHAT/PC), interviewed all the participants. The respiratory consultant made the respiratory illness diagnosis. The data were analyzed comparing the patient and the control group by using relative risk and adjusted odds ratios. RESULTS Of 391 patients with respiratory illness, 44.8% had a mental illness identified by GMHAT/PC interview compared with 24.3% of 177 attendants (controls). Anxiety (20.6%), depression (13.2%) and obsessive compulsive disorders (4.6%) were the most frequently identified mental disorders in the respiratory disease group. Chronic obstructive pulmonary disease and bronchial asthma when combined with rhinitis had a significantly higher prevalence of comorbid mental illness than those illnesses alone. CONCLUSION Patients with chronic respiratory illness have high mental health comorbidity. Physicians and practitioners can be trained to identify mental illness using computer-assisted tools such as GMHAT/PC (which is easy to use by clinicians and well accepted by patients). A holistic approach of providing care to such patients may improve their overall outcome and quality of life.

Cost analysis of a two-unit standby system with delayed replacement and better utilization of units

Abstract This paper develops the model for a system, having two identical units—one operative and the other cold standby. Each unit of the system has three modes—normal, partial failure and total failure. The replacement time of a failed unit by a standby unit is not negligible but is a random variable. System fails when both the units fail totally. Failure time distributions of units are exponential, whereas repair time distributions are arbitrary. Several reliability characteristics of interest to system designers and operations managers have been evaluated using the theory of regeneration point technique.

Cost-benefit analysis of a single server three-unit redundant system with inspection, delayed replacement and two types of repair

Abstract This paper deals with a redundant system with two types of spare units—a warm standby unit for instantaneous replacement at the time of failure of the active unit and a cold standby (stock) unit which can be replaced after a random amount of time. The type of the failure of operative or warm standby unit is detected by inspection only. The service facility plays the triple role of replacement, inspection and repair of a unit. Failure time distributions of operative and warm standby units are negative exponential whereas the distributions of replacement time, inspection time and repair times are arbitrary. The system has been studied by using regenerative points.

Prevalence and severity of asthma among Indian school children aged between 6 and 14 years: associations with parental smoking and traffic pollution.

Abstract Objective: Phase three of the International Study of Asthma and Allergy in Children (ISAAC) was carried out at various sites in India. The prevalence of asthma symptoms in school children and the effect of environmental tobacco smoke and traffic pollution on the occurrence of asthma were analysed. Methods: Two groups of school children, aged 6–7 yr and 13–14 yr, participated according to the ISAAC protocol. Schools were randomly selected and responses to the ISAAC questionnaire were recorded. Results: The prevalence of asthma was 5.35% in the 6–7 yr age group and 6.05% in the 13–14 yr age group. The odds ratios (ORs) for the risk of asthma in children with exposure to mild, moderate and heavy traffic pollution compared with minimal traffic pollution were 1.63 (95% CI: 1.43, 1.85), 1.71 (95% CI: 1.49, 1.96) and 1.53 (95% CI: 1.31, 1.78), respectively, in the younger group. Similarly, in the older group, they were 1.19 (95% CI: 1.04, 1.36), 1.51 (95% CI: 1.31, 1.75) and 1.51 (95% CI: 1.29, 1.76). Asthma was associated with maternal smoking [6–7 yr group: OR = 2.72 (2.05, 3.6); 13–14 yr group: OR = 2.14 (1.72, 2.66)] and paternal smoking [6–7 yr group: OR = 1.9 (1.70, 2.11); 13–14 yr group: OR = 1.21 (1.09, 1.34)]. Conclusions: The prevalence of asthma was lower in the 6–7 than the 13–14 yr age group. Environmental tobacco smoke and traffic pollution were the factors most strongly associated with asthma in Indian children.