A Multi-Modal Public Transport Solution For Male, Maldives

Male, the island capital of the Maldives, an archipelago of over 1000 islands in the Indian Ocean faces chronic traffic congestion. This 2 sq km island is home to over 100,000 people. There is a taxi service comprising of around 450 vehicles and a dhoni (ferry) service amounting to over 100 vessels to neighbouring islands. Male, which is fast becoming a small urban centre faces typical peak period traffic issues. The vehicle fleet is dominated by motor cycles which still contribute to traffic congestion in narrow streets. The taxi system which comprises of individually owned taxis registered with a ‘call centre’, provide limited services but fails during peak demand periods especially on rainy days. There is very little coordination between the ferry and taxi services. The paper is based on the results of a detailed urban transport planning study carried out in Male Urban Area which included passenger interviews, vehicle counts and travel time surveys covering all modes of motorized and non-motorized travel. This paper investigates the introduction of a mini-bus transport system that would provide easy transfers between ferries and major traffic generators and attractors. The contribution of a mini-bus service in the long-term is also discussed with respect to implementation of traffic demand management measures. This paper discuses the most appropriate type of vehicle that could be used and the potential framework for ownership and management of such a system taking in to consideration the multi-modal connectivity and also the service parameters for the operation of a successful minibus service. The paper also analyses the present operation of the ferry services and investigates its ownership and operation parameters for efficiency and cost effectiveness. The paper reports reasons for the varied efficiencies seen on the different routes and the impact the informal and loosely regulated service providers have on the key performance indicators of these services. It also compares cost between different ferry services and studies the relationship between the ownership structure, technology levels, productivity and fare.Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

Inter-observer and inter-examination variability of manual vertebral bone attenuation measurements on computed tomography

Objective: To determine inter-observer and inter-examination variability of manual attenuation measurements of the vertebrae in low-dose unenhanced chest computed tomography (CT). Methods: Three hundred and sixty-seven lung cancer screening trial participants who underwent baseline and repeat unenhanced low-dose CT after 3 months because of an indeterminate lung nodule were included. The CT attenuation value of the first lumbar vertebrae (L1) was measured in all CTs by one observer to obtain inter-examination reliability. Six observers performed measurements in 100 randomly selected CTs to determine agreement with limits of agreement and Bland-Altman plots and reliability with intraclass correlation coefficients (ICCs). Reclassification analyses were performed using a threshold of 110 HU to define osteoporosis. Results: Inter-examination reliability was excellent with an ICC of 0.92 (p < 0.001). Inter-examination limits of agreement ranged from -26 to 28 HU with a mean difference of 1 ± 14 HU. Inter-observer reliability ICCs ranged from 0.70 to 0.91. Inter-examination variability led to 11.2 % reclassification of participants and inter-observer variability led to 22.1 % reclassification. Conclusions: Vertebral attenuation values can be manually quantified with good to excellent inter-examination and inter-observer reliability on unenhanced low-dose chest CT. This information is valuable for early detection of osteoporosis on low-dose chest CT. Key Points: • Vertebral attenuation values can be manually quantified on low-dose unenhanced CT reliably.• Vertebral attenuation measurements may be helpful in detecting subclinical low bone density.• This could become of importance in the detection of osteoporosis

Detection of COPD, lung function decline and emphysema progression in heavy smokers

The work presented in this thesis has improved our insights in important determinants of lung function decline and emphysema progression in heavy smokers. Secondly, it improved our insight on the question which threshold of FEV1/FVC is most appropriate in diagnosing COPD. We showed in chapter 2 that the decline in lung function was the steepest in participants with higher lung function values. Regarding emphysema progression we found that it was least in the group with high lung function values and strongest in participants with lower lung function values. In chapter 3 we reported that a higher extent of CT-quantified emphysema was associated with a stronger decline in lung function and with an increased risk of the development of COPD during a 3-year follow-up. In addition we showed in chapter 4 that the distribution pattern also was associated with lung function decline. Participants with upper lobe predominant emphysema had a lower FEV1/FVC after follow-up than those with lower lobe predominant emphysema. In chapter 5 we examined the effects of duration of smoking cessation on lung function decline and progression of emphysema in heavy smokers. Smoking cessation for >4 years stabilized lung function decline and emphysema progression in both obstructed as non-obstructed participants. Our results show that smoking cessation is beneficial even in participants with a high smoking exposure. In chapter 6 we showed that the diffusion capacity of the lungs for carbon monoxide (Kco) was associated with lung function decline and progression of CT-quantified emphysema. In chapter 7 we showed that variants in the 15q24/25 locus are associated with lung function decline in active smokers. Current smokers homozygous for the rs1051730 A-allele or rs8034191 G-allele had significantly greater FEV1/FVC decline than homozygous carriers of wild-type alleles. These findings were replicated in an independent cohort of healthy smokers and subjects with varying COPD severity (GOLDI –IV). The same risk alleles conferred, respectively, a five- and four-fold increased risk to be referred for lung transplantation because of end-stage COPD. In chapter 8 we described the performance of a literature search of studies comparing diagnostic criteria of spirometric COPD: FEV1/FVC below the lower limit of normal (LLN) or below 70%. Prevalence rates according to the fixed criterion were higher than those according to the LLN. The major flaw of the founf cross sectional studies is that they compared the fixed criterion with the LLN, by taking the LLN as gold standard. In an attempt to investigate which threshold is to prefer we performed a diagnostic study (chapter 9). A panel diagnosis of COPD was used as reference standard and the FEV1/FVC <LLN an

Airway wall thickness associated with forced expiratory volume in 1 second decline and development of airflow limitation

Airway wall thickness and emphysema contribute to airflow limitation. We examined their association with lung function decline and development of airflow limitation in 2021 male smokers with and without airflow limitation. Airway wall thickness and emphysema were quantified on chest computed tomography and expressed as the square root of wall area of a 10-mm lumen perimeter (Pi10) and the 15th percentile method (Perc15), respectively. Baseline and follow-up (median (interquartile range) 3 (2.9-3.1) years) spirometry was available. Pi10 and Perc15 correlated with baseline forced expiratory volume in 1 s (FEV1) (r=-0.49 and 0.11, respectively (p<0.001)). Multiple linear regression showed that Pi10 and Perc15 at baseline were associated with a lower FEV1 after follow-up (p<0.05). For each SD increase in Pi10 and decrease in Perc15 the FEV1 decreased by 20mL and 30.2mL, respectively. The odds ratio for developing airflow limitation after 3 years was 2.45 for a 1-mm higher Pi10 and 1.46 for a 10-HU lower Perc15 (p<0.001). A greater degree of airway wall thickness and emphysema was associated with a higher FEV1 decline and development of airflow limitation after 3 years of follow-up

Low IgA Associated With Oropharyngeal Microbiota Changes and Lung Disease in Primary Antibody Deficiency

Common Variable Immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA) are primary antibody deficiencies characterized by hypogammaglobulinemia and recurrent infections, which can lead to structural airway disease (AD) and interstitial lung disease (ILD). We investigated associations between serum IgA, oropharyngeal microbiota composition and severity of lung disease in these patients. In this cross-sectional multicentre study we analyzed oropharyngeal microbiota composition of 86 CVID patients, 12 XLA patients and 49 healthy controls (HC) using next-generation sequencing of the 16S rRNA gene. qPCR was used to estimate bacterial load. IgA was measured in serum. High resolution CT scans were scored for severity of AD and ILD. Oropharyngeal bacterial load was increased in CVID patients with low IgA (p = 0.013) and XLA (p = 0.029) compared to HC. IgA status was associated with distinct beta (between-sample) diversity (p = 0.039), enrichment of (Allo)prevotella, and more severe radiographic lung disease (p = 0.003), independently of recent antibiotic use. AD scores were positively associated with Prevotella, Alloprevotella, and Selenomonas, and ILD scores with Streptococcus and negatively with Rothia. In clinically stable patients with CVID and XLA, radiographic lung disease was associated with IgA deficiency and expansion of distinct oropharyngeal bacterial taxa. Our findings highlight IgA as a potential driver of upper respiratory tract microbiota homeostasis

Pulmonary function and CT biomarkers as risk factors for cardiovascular events in male lung cancer screening participants : the NELSON study

Objective The objective of this study was to investigate the association of spirometry and pulmonary CT biomarkers with cardiovascular events. Methods In this lung cancer screening trial 3,080 male participants without a prior cardiovascular event were analysed. Fatal and non-fatal cardiovascular events were included. Spirometry included forced expiratory volume measured in units of one-second percent predicted (FEV1% predicted) and FEV1 divided by forced vital capacity (FVC; FEV1/FVC). CT examinations were quantified for coronary artery calcium volume, pulmonary emphysema (perc15) and bronchial wall thickness (pi10). Data were analysed via a Cox proportional hazard analysis, net reclassification improvement (NRI) and C-indices. Results 184 participants experienced a cardiovascular event during a median follow-up of 2.9 years. Age, pack-years and smoking status adjusted hazard ratios were 0.992 (95 % confidence interval (CI) 0.985-0.999) for FEV1% predicted, 1.000 (95% CI 0.986-1.015) for FEV1/FVC, 1.014 (95% CI 1.005-1.023) for perc15 per 10 HU, and 1.269 (95% CI 1.024-1.573) for pi10 per 1 mm. The incremental C-index ( Conclusions Pulmonary CT biomarkers and spirometry measurements were significantly associated with cardiovascular events, but did not contain clinically relevant independent prognostic information for cardiovascular events