Bounds on data limits for all-to-all comparison from combinatorial designs.

In situations where every item in a data set must be compared with every other item in the set, it may be desirable to store the data across a number of machines in such a way that any two data items are stored together on at least one machine. One way to evaluate the efficiency of such a distribution is by the largest fraction of the data it requires to be allocated to any one machine. The is a measure of the minimum of this value across all possible such distributions.

Association Between Expiratory Central Airway Collapse and Respiratory Outcomes Among Smokers.

Importance: Central airway collapse greater than 50% of luminal area during exhalation (expiratory central airway collapse [ECAC]) is associated with cigarette smoking and chronic obstructive pulmonary disease (COPD). However, its prevalence and clinical significance are unknown.

Objective: To determine whether ECAC is associated with respiratory morbidity in smokers independent of underlying lung disease.

Current Smoking Status Is Associated With Lower Quantitative CT Measures of Emphysema and Gas Trapping.

Purpose: The purposes of this study were to evaluate the effect of smoking status on quantitative computed tomography CT measures of low-attenuation areas (LAAs) on inspiratory and expiratory CT and to provide a method of adjusting for this effect.

Materials And Methods: A total of 6762 current and former smokers underwent spirometry and volumetric inspiratory and expiratory CT. Quantitative CT analysis was completed using open-source 3D Slicer software.

Normalizing computed tomography data reconstructed with different filter kernels: effect on emphysema quantification.

Objectives: To propose and evaluate a method to reduce variability in emphysema quantification among different computed tomography (CT) reconstructions by normalizing CT data reconstructed with varying kernels.

Methods: We included 369 subjects from the COPDGene study. For each subject, spirometry and a chest CT reconstructed with two kernels were obtained using two different scanners.

Reduced Bone Density and Vertebral Fractures in Smokers. Men and COPD Patients at Increased Risk.

Rationale: Former smoking history and chronic obstructive pulmonary disease (COPD) are potential risk factors for osteoporosis and fractures. Under existing guidelines for osteoporosis screening, women are included but men are not, and only current smoking is considered.

Objectives: To demonstrate the impact of COPD and smoking history on the risk of osteoporosis and vertebral fracture in men and women.

Radiological correlates and clinical implications of the paradoxical lung function response to β₂ agonists: an observational study.

Background: Bronchodilator response has been noted in a significant proportion of patients with chronic obstructive pulmonary disease (COPD). However, there are also reports of a paradoxical response to β₂ agonists resulting in bronchoconstriction. Asymptomatic bronchoconstriction is likely to be far more common than is symptomatic bronchoconstriction with β₂ agonists, but no systematic studies have been done.

Visual Assessment of CT Findings in Smokers With Nonobstructed Spirometric Abnormalities in The COPDGene Study.

Within the COPD Genetic Epidemiology (COPDGene) study population of cigarette smokers, 9% were found to be unclassifiable by the Global Initiative for chronic Obstructive Lung Disease (GOLD) criteria. This study was to identify the differences in computed tomography (CT) findings between this nonobstructed (GOLDU) group and a control group of smokers with normal lung function. This research was approved by the institutional review board of each institution.

Association between occupational exposure and lung function, respiratory symptoms, and high-resolution computed tomography imaging in COPDGene.

Rationale: Although occupational exposure to dust and fumes is considered a risk factor for chronic obstructive pulmonary disease, this determination has been limited by reliance on spirometry alone to assess disease severity in predominantly male populations.

Objectives: To determine the effect of occupational exposure on lung function, respiratory symptoms, and findings of emphysema and airway wall thickness measured using quantitative computed tomography in men and women.

Methods: COPDGene is a multicenter study of current and former smokers that underwent standardized volumetric chest computed tomography scans to assess airways, % emphysema, and % gas trapping.

FEV(1)/FEV(6) to diagnose airflow obstruction. Comparisons with computed tomography and morbidity indices.

Rationale: FVC is a difficult maneuver for many patients, and forced expiratory volume in 6 seconds (FEV6) has been proposed as a surrogate for FVC for the diagnosis of chronic obstructive pulmonary disease (COPD). Previous studies have performed head-to-head comparisons of these thresholds but did not examine their relationships with structural lung disease, symptoms, or exacerbations.

Objectives: To compare FEV1/FEV6 with FEV1/FVC in the diagnosis of COPD-related morbidity and structural lung disease as assessed by CT.

Relationships between airflow obstruction and quantitative CT measurements of emphysema, air trapping, and airways in subjects with and without chronic obstructive pulmonary disease.

Objective: This study evaluates the relationships between quantitative CT (QCT) and spirometric measurements of disease severity in cigarette smokers with and without chronic obstructive pulmonary disease (COPD).

Materials And Methods: Inspiratory and expiratory CT scans of 4062 subjects in the Genetic Epidemiology of COPD (COPDGene) Study were evaluated. Measures examined included emphysema, defined as the percentage of low-attenuation areas≤-950 HU on inspiratory CT, which we refer to as "LAA-950I"; air trapping, defined as the percentage of low-attenuation areas≤-856 HU on expiratory CT, which we refer to as "LAA-856E"; and the inner diameter, inner and outer areas, wall area, airway wall thickness, and square root of the wall area of a hypothetical airway of 10-mm internal perimeter of segmental and subsegmental airways.

Comparison of spirometric thresholds in diagnosing smoking-related airflow obstruction.

Background: Diagnosis of chronic obstructive pulmonary disease is based on detection of airflow obstruction on spirometry. There is no consensus regarding using a fixed threshold to define airflow obstruction versus using the lower limit of normal (LLN) adjusted for age. We compared the accuracy and discrimination of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommended fixed ratio of forced expiratory volume in the first second/forced vital capacity<0.

The chronic bronchitic phenotype of COPD: an analysis of the COPDGene Study.

Background: Chronic bronchitis (CB) in patients with COPD is associated with an accelerated lung function decline and an increased risk of respiratory infections. Despite its clinical significance, the chronic bronchitic phenotype in COPD remains poorly defined.

Methods: We analyzed data from subjects enrolled in the Genetic Epidemiology of COPD (COPDGene) Study.

Photoselective vaporization prostatectomy: experience with a novel 180 W 532 nm lithium triborate laser and fiber delivery system in living dogs.

Purpose: We studied vaporization parameters, and anatomical and histopathological outcomes of photoselective vaporization of the prostate with the novel GreenLight™ XPS™ 180 W, 532 nm lithium triborate laser and MoXy™ fiber in a survival model of living dogs. We compared these findings with those of the existing GreenLight HPS™ 120 W 532 nm lithium triborate laser photoselective vaporization of the prostate in living dogs.

Materials And Methods: Eight dogs underwent antegrade photoselective vaporization of the prostate with the 180 W laser delivered through a new 750 μm (vs the existing 600 μm core diameter), 50% larger, spot sized, side firing fiber.

Quantitative evaluation of high power effect on 532 nm laser vaporization of bovine prostate in vitro.

Purpose: We investigated the effect of 120 to 200 W high power levels on in vitro vaporization of bovine prostate using a custom-made 532 nm lithium triborate laser system.

Materials And Methods: Light (532 nm) delivered through a newly designed 750 microm core diameter side firing prototype fiber vaporized 114 bovine prostate tissue specimens in saline at 20C using a 2-dimensional scanning system. Various conditions were tested, including 120 to 200 W power, 1 to 5 mm working distance and 2 to 8 mm per second treatment speed.