WorldWideScience

Sample records for irreversible airflow limitation

  1. The usefulness of computed tomography in distinguishing between asthma with irreversible air-flow limitation and pulmonary emphysema

    International Nuclear Information System (INIS)

    Taniguchi, Hiroyuki; Ogawa, Kenji; Nakajima, Yoko; Amano, Masao; Kondo, Yasuhiro; Matsumoto, Kohei; Yokoyama, Sigeki; Matsubara, Kazuhito

    1988-01-01

    Chronic asthma may develop irreversible air-flow limitation and in this circumstance, it is clinically difficult to distinguish between asthma and pulmonary emphysema. Recently, it has been reported that computed tomography (CT) may assist in detecting changes in the lung specific for emphysema. We examined patients who suffered from asthma before the age of 45 which led to irreversible air-flow limitation (BA group; n = 17, mean age = 65.9) and patients with pulmonary emphysema (CPE group; n = 19, mean age = 69.8). Pulmonary function testing and CT were performed on all patients. In assessment of CT, areas of low attenuation and vascular disruption were considered to be suggestive of emphysema, and the Emphysema Score (ES) was calculated according to the method of Bergin et al. There was no significant difference in FEV1.0, % FEV1.0, % FEV1.0/FVC, % RV and RV/TLC between the BA group and the CPE group. In contrast, there was a significant decrease in the % DLco in CPE group compared with that of the BA group (p < 0.001). The ES in total lung was 54.9 ± 18.6 % in the CPE group and 7.8 ± 11.0 % in BA group (p < 0.001). There was a significant correlation between the % DLco and the ES in the CPE group (p < 0.01). We conclude that the CT is useful in distinguishing between asthma with irreversible air-flow limitation and pulmonary emphysema. (author)

  2. Occupational Exposures and Chronic Airflow Limitation

    Directory of Open Access Journals (Sweden)

    Helen Dimich-Ward

    1996-01-01

    Full Text Available The recent literature was reviewed to evaluate whether chronic airflow limitation is associated with occupational exposures to dusts. Only those studies that controlled for the effects of smoking were included. There is compelling evidence that exposure to inorganic dusts, such as from coal and hardrock mining or asbestos, are associated with the development of chronic airflow limitation, independently of pneumoconiosis. Nonsmoking gold miners are particularly at high risk of airflow obstruction and emphysema. Findings from studies of organic dusts, such as exposures to wood, cotton, grain or other agricultural dusts, or to mixed dust exposures, were less consistent but tended to show positive dose-response associations. In the majority of studies, no statistical interaction was shown between dust exposures and smoking; however, the effects of the dust exposures were often more pronounced. An occupational history should be considered, in addition to a smoking history, as an integral part of an investigation of chronic airflow limitation in a patient.

  3. Majority of never-smokers with airflow limitation do not have asthma

    DEFF Research Database (Denmark)

    Çolak, Yunus; Afzal, Shoaib; Nordestgaard, Børge G

    2016-01-01

    BACKGROUND: A substantial proportion of individuals with airflow limitation are never-smokers. However, whether never-smokers with airflow limitation have undiagnosed asthma is unknown. We hypothesised that the majority of never-smokers with respiratory symptoms and airflow limitation but without...... known asthma have undiagnosed asthma by comparing characteristics and prognosis in never-smokers with airflow limitation and asthma (NS+AFL+A) with never-smokers with airflow limitation but without asthma (NS+AFL-A). METHODS: Among 94 079 participants aged 20-100 years from the general population, 39...... 102 (42%) were never-smokers. In this group, 13 719 (35%) reported to have respiratory symptoms of whom 1610 (12%) had airflow limitation. We investigated characteristics and risk of complications (asthma or COPD exacerbations, pneumonias and all-cause mortality) and comorbidities (lung cancer...

  4. Factors associated with persistent airflow limitation in severe asthma

    NARCIS (Netherlands)

    ten Brinke, A.; Zwinderman, A. H.; Sterk, P. J.; Rabe, K. F.; Bel, E. H.

    2001-01-01

    Persistent airflow limitation can develop in nonsmoking patients with asthma. However, the prevalence and risk factors for airways obstruction with incomplete reversibility in asthma are unknown. We assessed the prevalence of persistent airflow limitation (defined as postbronchodilator FEV(1) or

  5. Computed tomography structural lung changes in discordant airflow limitation.

    Directory of Open Access Journals (Sweden)

    Firdaus A A Mohamed Hoesein

    Full Text Available There is increasing evidence that structural lung changes may be present before the occurrence of airflow limitation as assessed by spirometry. This study investigated the prevalence of computed tomography (CT quantified emphysema, airway wall thickening and gas trapping according to classification of airflow limitation (FEV1/FVC 70%; group 2LLN; and group 370% but FEV1 <80% predicted, were excluded. Multivariate regression analysis correcting for covariates was used to asses the extent of emphysema, airway wall thickening and gas trapping according to three groups of airflow limitation.Mean (standard deviation age was 62.5 (5.2 years and packyears smoked was 41.0 (18.0. Group 2 subjects when compared to group 1 had a significantly lower 15(th percentile, -920.6 HU versus -912.2 HU; a higher Pi10, 2.87 mm versus 2.57 mm; and a higher E/I-ratio, 88.6% versus 85.6% (all p<0.001.Subjects with an FEV1/FVC<70%, but above the LLN, have a significant greater degree of structural lung changes on CT compared to subjects without airflow limitation.

  6. Risk factors for persistent airflow limitation: Analysis of 306 patients with asthma

    OpenAIRE

    Wang, Lingcheng; Gao, Shuncui; Zhu, Wei; Su, Jun

    2014-01-01

    Objectives : To determine the risk factors associated with persistent airflow limitation in patients with asthma. Method s: This study was designed and carried out in the department of respiratory medicine, fourth People?s Hospital of Jinan City, Shandong province, China between Jan 2012 and Dec 2012. Three hundred and six asthma patients participating in the study were divided into persistent airflow limitation group (PAFL) and no persistent airflow limitation group (NPAFL). The patients par...

  7. Relationships among smoking habits, airflow limitations, and metabolic abnormalities in school workers.

    Science.gov (United States)

    Horie, Masafumi; Noguchi, Satoshi; Tanaka, Wakae; Goto, Yasushi; Yoshihara, Hisanao; Kawakami, Masaki; Suzuki, Masaru; Sakamoto, Yoshio

    2013-01-01

    Chronic obstructive pulmonary disease is caused mainly by habitual smoking and is common among elderly individuals. It involves not only airflow limitation but also metabolic disorders, leading to increased cardiovascular morbidity and mortality. We evaluated relationships among smoking habits, airflow limitation, and metabolic abnormalities. Between 2001 and 2008, 15,324 school workers (9700 males, 5624 females; age: ≥ 30 years) underwent medical checkups, including blood tests and spirometry. They also responded to a questionnaire on smoking habits and medical history. Airflow limitation was more prevalent in current smokers than in ex-smokers and never-smokers in men and women. The frequency of hypertriglyceridemia was higher in current smokers in all age groups, and those of low high-density-lipoprotein cholesterolemia and diabetes mellitus were higher in current smokers in age groups ≥ 40 s in men, but not in women. There were significant differences in the frequencies of metabolic abnormalities between subjects with airflow limitations and those without in women, but not in men. Smoking index was an independent factor associated with increased frequencies of hypertriglyceridemia (OR 1.015; 95% CI: 1.012-1.018; psmoking cessation was an independent factor associated with a decreased frequency of hypertriglyceridemia (0.984; 0.975-0.994; p = 0.007). Habitual smoking causes high incidences of airflow limitation and metabolic abnormalities. Women, but not men, with airflow limitation had higher frequencies of metabolic abnormalities.

  8. Prevalence of asthma with airflow limitation, COPD, and COPD with variable airflow limitation in older subjects in a general Japanese population: the Hisayama Study.

    Science.gov (United States)

    Matsumoto, Koichiro; Seki, Nanae; Fukuyama, Satoru; Moriwaki, Atsushi; Kan-o, Keiko; Matsunaga, Yuko; Noda, Naotaka; Yoshida, Makoto; Koto, Hiroshi; Takata, Shohei; Nakanishi, Yoichi; Kiyohara, Yutaka; Inoue, Hiromasa

    2015-01-01

    Elucidating the prevalence of asthma and chronic obstructive pulmonary disease (COPD) is important for designing a public health strategy. Recent studies have discriminated a phenotype of COPD with variable airflow limitation (COPD-VAL) associated with asthma-COPD overlap syndrome. Its prevalence remains uncertain. The age and occupational distributions in the town of Hisayama and in Japan are nearly identical. Each disease's prevalence was estimated for the town's residents. In 2008, town residents (≥ 40 years) were solicited to participate in a health checkup. Individuals with abnormal spirometry (forced expiratory volume in 1s/forced vital capacity [FEV1/FVC]fashion reviewed their medical records, including bronchodilator reversibility. Individuals with airflow limitation were classified as having asthma, COPD, COPD-VAL, or other diseases. The prevalence of each disease was then estimated. A total of 2100 residents (43.4% of residents in the age group) completed spirometry. In 455 residents with abnormal spirometry, 190 residents had further evaluations, and the medical records of 174 residents were reviewed. The prevalence of asthma with airflow limitation, COPD, and COPD-VAL, were 2.0%, 8.4%, and 0.9%, respectively. The prevalence of COPD and COPD-VAL were higher in men and smokers than in women and never-smokers. The prevalence of COPD, but not COPD-VAL or asthma, increased with age. The prevalence of asthma with airflow limitation, COPD, and COPD-VAL were estimated in a population of residents (≥ 40 years) in Hisayama. Copyright © 2014 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

  9. Prevalence of airflow limitation in outpatients with cardiovascular diseases in Japan

    Directory of Open Access Journals (Sweden)

    Onishi K

    2014-05-01

    Full Text Available Katsuya Onishi,1 Daisuke Yoshimoto,2 Gerry W Hagan,3 Paul W Jones4 1Onishi Heart Clinic, Mie, 2Medical Affairs Respiratory, GlaxoSmithKline KK, Tokyo, Japan; 3Independent Consultant, Marbella, Spain; 4Division of Clinical Science, St George's, University of London, London, UK Background and objectives: Cardiovascular disease (CVD and chronic obstructive pulmonary disease (COPD commonly coexist and share common risk factors. The prevalence of COPD in outpatients with a smoking history and CVD in Japan is unknown. The aim of this study was to determine the proportion of Japanese patients with a smoking history being treated for CVD who have concurrent airflow limitation compatible with COPD. A secondary objective was to test whether the usage of lung function tests performed in the clinic influenced the diagnosis rate of COPD in the patients identified with airflow limitation. Methods: In a multicenter observational prospective study conducted at 17 centers across Japan, the prevalence of airflow limitation compatible with COPD (defined as forced expiratory volume (FEV1/FEV6 <0.73, by handheld spirometry was investigated in cardiac outpatients ≥40 years old with a smoking history who routinely visited the clinic for their CVD. Each patient completed the COPD Assessment Test prior to spirometry testing. Results: Data were available for 995 patients with a mean age of 66.6±10.0 years, of whom 95.5% were male. The prevalence of airflow limitation compatible with COPD was 27.0% (n=269, and 87.7% of those patients (n=236 did not have a prior diagnosis of COPD. The prevalence of previously diagnosed airflow limitation was higher in sites with higher usage of lung function testing (14.0%, 15.2% respectively compared against sites where it is performed seldom (11.1%, but was still low. Conclusion: The prevalence of airflow limitation in this study indicates that a quarter of outpatients with CVD have COPD, almost all of whom are undiagnosed. This

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

    NARCIS (Netherlands)

    Hoesein, Firdaus A. A. Mohamed; de Jong, Pim A.; Lammers, Jan-Willem J.; Mali, Willem P. T. M.; Schmidt, Michael; de Koning, Harry J.; van der Aalst, Carlijn; Oudkerk, Matthijs; Vliegenthart, Rozemarijn; Groen, Harry J. M.; van Ginneken, Bram; van Rikxoort, Eva M.; Zanen, Pieter

    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

  11. Current status of nuclear medicine in chronic airflow limitation

    International Nuclear Information System (INIS)

    Clarke, S.W.; Agnew, J.E.; Royal Free Hospital, London

    1987-01-01

    Radionuclide imaging, quite apart from its role in the diagnosis of pulmonary embolism, offers information about the distribution of ventilatory and perfusion abnormalities within the lung. The extent of ventilatory abnormality seen can be related to the severity of airways obstruction as assessed spirometrically, whilst abnormalities in the matching of perfusion to ventilation can be related to the severity of hypoxaemia in patients with chronic airflow limitation. Clearance of mucus from the lungs of patients with chronic mucus hypersection may be assessed by following the clearance rate of insoluble radioaerosol particles; by such means the relative contributions of mucociliary transport and of cough to the overall clearance can be observed. Clearance is often severely impaired in patients with airways obstruction; the radioaerosol technique can be used to determine the effects of drug or physiotherapy treatment. Chronic airflow limitation leading to hypoxaemia can be associated with pulmonary artery hypertension and right ventricular hypertrophy - this may be investigated noninvasively by a radionuclide test of right ventricular ejection fraction. (orig.)

  12. Current status of nuclear medicine in chronic airflow limitation

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, S.W.; Agnew, J.E.

    1987-06-01

    Radionuclide imaging, quite apart from its role in the diagnosis of pulmonary embolism, offers information about the distribution of ventilatory and perfusion abnormalities within the lung. The extent of ventilatory abnormality seen can be related to the severity of airways obstruction as assessed spirometrically, whilst abnormalities in the matching of perfusion to ventilation can be related to the severity of hypoxaemia in patients with chronic airflow limitation. Clearance of mucus from the lungs of patients with chronic mucus hypersection may be assessed by following the clearance rate of insoluble radioaerosol particles; by such means the relative contributions of mucociliary transport and of cough to the overall clearance can be observed. Clearance is often severely impaired in patients with airways obstruction; the radioaerosol technique can be used to determine the effects of drug or physiotherapy treatment. Chronic airflow limitation leading to hypoxaemia can be associated with pulmonary artery hypertension and right ventricular hypertrophy - this may be investigated noninvasively by a radionuclide test of right ventricular ejection fraction.

  13. Majority of never-smokers with airflow limitation do not have asthma: the Copenhagen General Population Study.

    Science.gov (United States)

    Çolak, Yunus; Afzal, Shoaib; Nordestgaard, Børge G; Lange, Peter

    2016-07-01

    A substantial proportion of individuals with airflow limitation are never-smokers. However, whether never-smokers with airflow limitation have undiagnosed asthma is unknown. We hypothesised that the majority of never-smokers with respiratory symptoms and airflow limitation but without known asthma have undiagnosed asthma by comparing characteristics and prognosis in never-smokers with airflow limitation and asthma (NS+AFL+A) with never-smokers with airflow limitation but without asthma (NS+AFL-A). Among 94 079 participants aged 20-100 years from the general population, 39 102 (42%) were never-smokers. In this group, 13 719 (35%) reported to have respiratory symptoms of whom 1610 (12%) had airflow limitation. We investigated characteristics and risk of complications (asthma or COPD exacerbations, pneumonias and all-cause mortality) and comorbidities (lung cancer, ischaemic heart disease, myocardial infarction, deep venous thrombosis and PE) during 4.5 years median follow-up. NS+AFL-A compared with NS+AFL+A reported less allergy and respiratory symptoms, and had higher FEV1 and lower levels of eosinophils and IgE in peripheral blood. NS+AFL+A had increased risk of asthma and COPD exacerbations, but not of pneumonias; adjusted HRs in NS+AFL+A compared with NS+AFL-A were 16 (95% CI 3.7 to 73) for asthma exacerbations and 15 (2.8 to 80) for COPD exacerbations. Still, NS+AFL-A had increased risk of COPD exacerbations and pneumonias, but not of asthma exacerbations; adjusted HRs in NS+AFL-A compared with never-smokers without airflow limitation or asthma (NS-AFL-A) were 7.7 (2.8 to 21) for COPD exacerbations and 1.7 (1.3 to 2.3) for pneumonias. Risk of comorbidities or all-cause mortality was not increased in NS+AFL-A or NS+AFL+A compared with NS-AFL-A. Majority of NS+AFL-A do not seem to have undiagnosed asthma and may instead have airflow limitation caused by other risk factors. Published by the BMJ Publishing Group Limited. For permission to use (where not

  14. Validity of peak expiratory flow measurement in assessing reversibility of airflow obstruction.

    Science.gov (United States)

    Dekker, F W; Schrier, A C; Sterk, P J; Dijkman, J H

    1992-01-01

    BACKGROUND: Assessing the reversibility of airflow obstruction by peak expiratory (PEF) measurements would be practicable in general practice, but its usefulness has not been investigated. METHODS: PEF measurements were performed (miniWright peak flow meter) in 73 general practice patients (aged 40 to 84) with a history of asthma or chronic obstructive lung disease before and after 400 micrograms inhaled sulbutamol. The change in PEF was compared with the change in forced expiratory volume in one second (FEV1). Reversible airflow obstruction was analysed in two ways according to previous criteria. When defined as a 9% or greater increase in FEV1 expressed as a percentage of predicted values reversibility was observed in 42% of patients. Relative operating characteristic analysis showed that an absolute improvement in PEF of 60 l/min or more gave optimal discrimination between patients with reversible and irreversible airflow obstruction (the sensitivity and specificity of an increase of 60 l/min in detecting a 9% or more increase in FEV1 as a percentage of predicted values were 68% and 93% respectively, with a positive predictive value of 87%). When defined as an increase of 190 ml or more in FEV1, reversible airflow obstruction was observed in 53% of patients. Again an absolute improvement in PEF of 60 l/min or more gave optimal discrimination between patients with reversible and irreversible airflow obstruction (sensitivity 56%, specificity 94%, and positive predictive value 92%). CONCLUSION: Absolute changes in PEF can be used as a simple technique to diagnose reversible airflow obstruction in patients from general practice. PMID:1519192

  15. Performance of an irreversible quantum Ericsson cooler at low temperature limit

    International Nuclear Information System (INIS)

    Wu Feng; Chen Lingen; Wu Shuang; Sun Fengrui

    2006-01-01

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible quantum Ericsson cooler with spin-1/2. The cooler is studied with the losses of heat resistance, heat leakage and internal irreversibility. The optimal relationship between the dimensionless cooling load R * versus the coefficient of performance ε for the irreversible quantum Ericsson cooler is derived. In particular, the performance characteristics of the cooler at the low temperature limit are discussed

  16. Main bronchial diverticula in the subcarinal region: Their relation to airflow limitations

    International Nuclear Information System (INIS)

    Higuchi, Takeshi; Takahashi, Naoya; Shiotani, Motoi; Sato, Suguru; Ohta, Atsushi; Maeda, Haruo; Nakajima, Haruhiko; Itoh, Kazuhiko; Tsukada, Hiroki

    2012-01-01

    Background. To date, bronchial diverticula have generally been treated as a pathological condition associated with chronic obstructive pulmonary disease (COPD), although only a limited amount of published information is available on the relationship between bronchial diverticula as depicted by multidetector computed tomography (MDCT) and airflow limitations. Purpose. To evaluate the relationship between airflow limitations and main bronchial diverticula in the subcarinal region using spirometry and thin-section MDCT. Material and Methods. A total of 189 consecutive adult patients were retrospectively evaluated based on spirometry and thin-section MDCT of the chest. All examinations were performed at our institution between June and October 2008. The study group included 70 women and 119 men with a mean age of 65 years (range 19-86 years). The relationship between the FEV1% and bronchial diverticula in the subcarinal region was analyzed (Student's t-test). Results. The indications for conducting the examinations were pulmonary diseases (82 patients), cardiovascular diseases (22), extrapulmonary malignancies (74), and other conditions (11). A total of 84/189 (44.4%) patients showed bronchial diverticula, and the FEV 1 % of 70/84 (83.3%) patients was above 70. The FEV 1 % of patients with lesions ranged from 26.0 to 97.8 (mean 76.8), whereas the range was 28.1-94.4 (mean 73.7) in those without lesions. There was no significant association between the FEV 1 % and the presence of subcarinal bronchial diverticula (P > 0.05). Conclusion. Our data demonstrate that thin-section chest CT commonly demonstrates main bronchial diverticula in the subcarinal region in patients without airflow limitations. We propose that the presence of a small number of tiny bronchial diverticula under the carina may not be a criterion for the diagnosis of COPD

  17. Main bronchial diverticula in the subcarinal region: Their relation to airflow limitations

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Takeshi; Takahashi, Naoya; Shiotani, Motoi; Sato, Suguru; Ohta, Atsushi; Maeda, Haruo; Nakajima, Haruhiko; Itoh, Kazuhiko; Tsukada, Hiroki (Department of Radiology, Respiratory Medicine, Niigata City General Hospital, Niigata-city, Niigata-ken (Japan)), Email: higuchi@hosp.niigata.niigata.jp

    2012-02-15

    Background. To date, bronchial diverticula have generally been treated as a pathological condition associated with chronic obstructive pulmonary disease (COPD), although only a limited amount of published information is available on the relationship between bronchial diverticula as depicted by multidetector computed tomography (MDCT) and airflow limitations. Purpose. To evaluate the relationship between airflow limitations and main bronchial diverticula in the subcarinal region using spirometry and thin-section MDCT. Material and Methods. A total of 189 consecutive adult patients were retrospectively evaluated based on spirometry and thin-section MDCT of the chest. All examinations were performed at our institution between June and October 2008. The study group included 70 women and 119 men with a mean age of 65 years (range 19-86 years). The relationship between the FEV1% and bronchial diverticula in the subcarinal region was analyzed (Student's t-test). Results. The indications for conducting the examinations were pulmonary diseases (82 patients), cardiovascular diseases (22), extrapulmonary malignancies (74), and other conditions (11). A total of 84/189 (44.4%) patients showed bronchial diverticula, and the FEV{sub 1}% of 70/84 (83.3%) patients was above 70. The FEV{sub 1}% of patients with lesions ranged from 26.0 to 97.8 (mean 76.8), whereas the range was 28.1-94.4 (mean 73.7) in those without lesions. There was no significant association between the FEV{sub 1}% and the presence of subcarinal bronchial diverticula (P > 0.05). Conclusion. Our data demonstrate that thin-section chest CT commonly demonstrates main bronchial diverticula in the subcarinal region in patients without airflow limitations. We propose that the presence of a small number of tiny bronchial diverticula under the carina may not be a criterion for the diagnosis of COPD

  18. Airflow limitation in people living with HIV and matched uninfected controls

    DEFF Research Database (Denmark)

    Ronit, Andreas; Lundgren, Jens; Afzal, Shoaib

    2018-01-01

    -matched controls from the Copenhagen General Population Study were included. Lung function was assessed using FEV1 and FVC, while airflow limitation was defined by the lower limit of normal (LLN) of FEV1/FVC and by FEV1/FVClinear regression models were used......INTRODUCTION: Whether HIV influences pulmonary function remains controversial. We assessed dynamic pulmonary function in people living with HIV (PLWHIV) and uninfected controls. METHODS: A total of 1098 PLWHIV from the Copenhagen Co-morbidity in HIV infection study and 12 161 age-matched and sex...

  19. Prevalence of Airflow Limitation Defined by Pre- and Post-Bronchodilator Spirometry in a Community-Based Health Checkup: The Hisayama Study.

    Science.gov (United States)

    Fukuyama, Satoru; Matsumoto, Koichiro; Kaneko, Yasuko; Kan-o, Keiko; Noda, Naotaka; Tajiri-Asai, Yukari; Nakano, Takako; Ishii, Yumiko; Kiyohara, Yutaka; Nakanishi, Yoichi; Inoue, Hiromasa

    2016-02-01

    Spirometry in health checkup may contribute to early diagnosis of chronic obstructive pulmonary disease (COPD) and asthma. Although post-bronchodilator airflow limitation is essential for definite diagnosis of COPD and post-bronchodilator normalization of airflow is suggestive of asthma, this test has not been prevailed in health checkup. The objective of this study was to estimate the prevalence of airflow limitation defined by pre- and post-bronchodilator spirometry in health checkup. Post-bronchodilator spirometry was conducted for participants with airflow limitation in a town-wide health checkup for residents aged 40 years and older in Hisayama, a town in the western part of Japan. The prevalence of pre- and post-bronchodilator airway limitation defined by FEV1/FVC spirometry. In males, the age of current smokers was significantly younger than those of never smokers and former smokers. In females, the ages of current- and former smokers were significantly younger than never smokers. The values of %FEV1 and %FVC in current smokers were significantly lower than those in former smokers and never smokers. Two hundred sixty nine subjects, 85% of total subjects with a pre-bronchodilator FEV1/FVC spirometry. The prevalence of pre-bronchodilator airflow limitation was 14.6% in males and 13.7% in females, and the prevalence of post-bronchodilator airway limitation was 8.7% and 8.7%, respectively. Post-bronchodilator spirometry in health checkup would reduce the number of subjects with probable COPD to two-third. Recommendation for those examinees to take further evaluations may pave the way for early intervention.

  20. Reversing the irreversible: From limit cycles to emergent time symmetry

    Science.gov (United States)

    Cortês, Marina; Smolin, Lee

    2018-01-01

    In 1979 Penrose hypothesized that the arrows of time are explained by the hypothesis that the fundamental laws are time irreversible [R. Penrose, in General Relativity: An Einstein Centenary Survey (1979)]. That is, our reversible laws, such as the standard model and general relativity are effective, and emerge from an underlying fundamental theory which is time irreversible. In [M. Cortês and L. Smolin, Phys. Rev. D 90, 084007 (2014), 10.1103/PhysRevD.90.084007; 90, 044035 (2014), 10.1103/PhysRevD.90.044035; 93, 084039 (2016), 10.1103/PhysRevD.93.084039] we put forward a research program aiming at realizing just this. The aim is to find a fundamental description of physics above the Planck scale, based on irreversible laws, from which will emerge the apparently reversible dynamics we observe on intermediate scales. Here we continue that program and note that a class of discrete dynamical systems are known to exhibit this very property: they have an underlying discrete irreversible evolution, but in the long term exhibit the properties of a time reversible system, in the form of limit cycles. We connect this to our original model proposal in [M. Cortês and L. Smolin, Phys. Rev. D 90, 084007 (2014), 10.1103/PhysRevD.90.084007], and show that the behaviors obtained there can be explained in terms of the same phenomenon: the attraction of the system to a basin of limit cycles, where the dynamics appears to be time reversible. Further than that, we show that our original models exhibit the very same feature: the emergence of quasiparticle excitations obtained in the earlier work in the space-time description is an expression of the system's convergence to limit cycles when seen in the causal set description.

  1. Non-atopic males with adult onset asthma are at risk of persistent airflow limitation

    NARCIS (Netherlands)

    Amelink, M.; de Nijs, S. B.; Berger, M.; Weersink, E. J.; ten Brinke, A.; Sterk, P. J.; Bel, E. H.

    2012-01-01

    Background Patients with asthma have on average a more rapid decline in FEV1 as compared with the general population. Recent cluster analysis has revealed different asthma phenotypes that can be distinguished by age of onset and reversibility of airflow limitation. Objective This study aimed at

  2. Adenosine 5'-Monophosphate Aerosol Challenge Does Not Provoke Airflow Limitation in Healthy Cats

    Directory of Open Access Journals (Sweden)

    K. Vondráková

    2006-01-01

    Full Text Available The purpose of our study was to investigate the effects of nebulized adenosine 5'- monophosphate on airflow limitation in healthy cats determined by barometric whole body plethysmography (BWBP, in comparison to the effects of carbachol. Ten healthy 4- to 6-year-old domestic shorthair cats were included in the study. Each cat was placed in a BWBP plexiglass chamber (volume 38 l. Changes in box pressure were measured at baseline and after nebulization of vehicle and increasing concentrations of carbachol and adenosine 5'- monophosphate. Airway responsiveness was monitored as increases in enhanced pause (PENH, a unitless variable derived from dose-response curves estimating airflow limitation. The chosen endpoint was the agonist concentration which increased PENH to 300% of the value obtained after saline nebulization (PCPENH 300. Inter-day repeatability of measurements was assessed by repeated bronchoprovocations with both agonists 2-3 days apart. For carbachol, PCPENH300 was reached in all cats and correlated significantly between days (mean ± SD; 0.54 ± 0.42 mg/ml and 0.64 ± 0.45 mg/ml respectively; r = 0.58, p < 0.05 In contrast, we found no reaction to adenosine 5'- monophosphate even with the highest concentration nebulized during both measurements. At baseline, mean ± SD PENH was 0.47 ± 0.18 and 0.58 ± 0.24 (measurements 1 and 2, whereas PENH after 500 mg/ml adenosine 5'- monophosphate was 0.46 ± 0.20 and 0.71 ± 0.37. All bronchoprovocation tests were well tolerated by the cats. We conclude that healthy airways in cats do not demonstrate airway responsiveness to inhaled adenosine 5'- monophosphate. This is in agreement with observations in humans as well as our previous findings in dogs, where adenosine 5'- monophosphate had no effect on healthy canine airways, but caused significant airflow limitation after induction of acute bronchitis. To define the value of bronchoprovocation testing with adenosine 5'- monophosphate in the feline

  3. Occupational exposure to vapor, gas, dust, or fumes and chronic airflow limitation, COPD, and emphysema: the Swedish CArdioPulmonary BioImage Study (SCAPIS pilot

    Directory of Open Access Journals (Sweden)

    Torén K

    2017-11-01

    Full Text Available Kjell Torén,1 Jenny Vikgren,2 Anna-Carin Olin,1 Annika Rosengren,3 Göran Bergström,3 John Brandberg2 1Section of Occupational and Environmental Medicine, Institute of Medicine, Sahlgrenska Academy, 2Department of Radiology, Institute of Clinical Sciences, 3Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Background: The aim of this study was to estimate the occupational burden of airflow limitation, chronic airflow limitation, COPD, and emphysema.Materials and methods: Subjects aged 50–64 years (n=1,050 were investigated with forced expiratory volume in 1 s (FEV1 and forced vital capacity (FVC. Airflow limitation was defined as FEV1/FVC <0.7 before bronchodilation. Chronic airflow limitation was defined after bronchodilation either according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD as FEV1/FVC <0.7 or according to the lower limit of normal (LLN approach as FEV1/FVC < LLN. COPD was defined as chronic airflow limitation (GOLD in combination with dyspnea, wheezing, or chronic bronchitis. Emphysema was classified according to findings from computed tomography of the lungs. Occupational exposure was defined as self-reported occupational exposure to vapor, gas, dust, or fumes (VGDF. Odds ratios (OR were calculated in models adjusted for age, gender, and smoking; population-attributable fractions and 95% CI were also calculated.Results: There were significant associations between occupational exposure to VGDF and COPD (OR 2.7, 95% CI 1.4–51, airflow limitation (OR 1.8, 95% CI 1.3–2.5, and emphysema (OR 1.8, 95% CI 1.1–3.1. The associations between occupational exposure to VGDF and chronic airflow limitation were weaker, and for the OR, the CIs included unity. The population-attributable fraction for occupational exposure to VGDF was 0.37 (95% CI 0.23–0.47 for COPD and 0.23 (95% CI 0.05–0.35 for emphysema.Conclusion: The

  4. Persistent airflow limitation in adult-onset nonatopic asthma is associated with serologic evidence of Chlamydia pneumoniae infection

    NARCIS (Netherlands)

    ten Brinke, A.; van Dissel, J. T.; Sterk, P. J.; Zwinderman, A. H.; Rabe, K. F.; Bel, E. H.

    2001-01-01

    Persistent airflow limitation may develop in patients with asthma, particularly in adults with nonatopic (intrinsic) disease. Although the underlying mechanisms are still unknown, respiratory infections might be involved. We investigated the annual loss of lung function in relation to seropositivity

  5. Overweight and obesity may lead to under-diagnosis of airflow limitation

    DEFF Research Database (Denmark)

    Çolak, Yunus; Marott, Jacob Louis; Vestbo, Jørgen

    2015-01-01

    BACKGROUND: The prevalence of obesity has increased during the last decades and varies from 10-20% in most European countries to approximately 32% in the United States. However, data on how obesity affects the presence of airflow limitation (AFL) defined as a reduced ratio between forced expiratory...... volume in 1 second (FEV1) and forced vital capacity (FVC) are scarce. METHODS: Data was derived from the third examination of the Copenhagen City Heart Study from 1991 until 1994 (n = 10,135). We examine the impact of different adiposity markers (weight, body mass index (BMI), waist circumference, waist......-diagnosis and under-treatment of COPD among individuals with overweight and obesity....

  6. Paired maximum inspiratory and expiratory plain chest radiographs for assessment of airflow limitation in chronic obstructive pulmonary disease

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Takashi, E-mail: tkino@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Kawayama, Tomotaka, E-mail: kawayama_tomotaka@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Imamura, Youhei, E-mail: mamura_youhei@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Sakazaki, Yuki, E-mail: sakazaki@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Hirai, Ryo, E-mail: hirai_ryou@kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Ishii, Hidenobu, E-mail: shii_hidenobu@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Suetomo, Masashi, E-mail: jin_t_f_c@yahoo.co.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Matsunaga, Kazuko, E-mail: kmatsunaga@kouhoukai.or.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Azuma, Koichi, E-mail: azuma@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan); Fujimoto, Kiminori, E-mail: kimichan@med.kurume-u.ac.jp [Department of Radiology, Kurume University School of Medicine, Kurume (Japan); Hoshino, Tomoaki, E-mail: hoshino@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Medicine, Kurume University School of Medicine, Kurume (Japan)

    2015-04-15

    Highlights: •It is often to use computed tomography (CT) scan for diagnosis of chronic obstructive pulmonary disease. •CT scan is more expensive and higher. •A plane chest radiography more simple and cheap. Moreover, it is useful as detection of pulmonary emphysema, but not airflow limitation. •Our study demonstrated that the maximum inspiratory and expiratory plane chest radiography technique could detect severe airflow limitations. •We believe that the technique is helpful to diagnose the patients with chronic obstructive pulmonary disease. -- Abstract: Background: The usefulness of paired maximum inspiratory and expiratory (I/E) plain chest radiography (pCR) for diagnosis of chronic obstructive pulmonary disease (COPD) is still unclear. Objectives: We examined whether measurement of the I/E ratio using paired I/E pCR could be used for detection of airflow limitation in patients with COPD. Methods: Eighty patients with COPD (GOLD stage I = 23, stage II = 32, stage III = 15, stage IV = 10) and 34 control subjects were enrolled. The I/E ratios of frontal and lateral lung areas, and lung distance between the apex and base on pCR views were analyzed quantitatively. Pulmonary function parameters were measured at the same time. Results: The I/E ratios for the frontal lung area (1.25 ± 0.01), the lateral lung area (1.29 ± 0.01), and the lung distance (1.18 ± 0.01) were significantly (p < 0.05) reduced in COPD patients compared with controls (1.31 ± 0.02 and 1.38 ± 0.02, and 1.22 ± 0.01, respectively). The I/E ratios in frontal and lateral areas, and lung distance were significantly (p < 0.05) reduced in severe (GOLD stage III) and very severe (GOLD stage IV) COPD as compared to control subjects, although the I/E ratios did not differ significantly between severe and very severe COPD. Moreover, the I/E ratios were significantly correlated with pulmonary function parameters. Conclusions: Measurement of I/E ratios on paired I/E pCR is simple and

  7. Paired maximum inspiratory and expiratory plain chest radiographs for assessment of airflow limitation in chronic obstructive pulmonary disease

    International Nuclear Information System (INIS)

    Kinoshita, Takashi; Kawayama, Tomotaka; Imamura, Youhei; Sakazaki, Yuki; Hirai, Ryo; Ishii, Hidenobu; Suetomo, Masashi; Matsunaga, Kazuko; Azuma, Koichi; Fujimoto, Kiminori; Hoshino, Tomoaki

    2015-01-01

    Highlights: •It is often to use computed tomography (CT) scan for diagnosis of chronic obstructive pulmonary disease. •CT scan is more expensive and higher. •A plane chest radiography more simple and cheap. Moreover, it is useful as detection of pulmonary emphysema, but not airflow limitation. •Our study demonstrated that the maximum inspiratory and expiratory plane chest radiography technique could detect severe airflow limitations. •We believe that the technique is helpful to diagnose the patients with chronic obstructive pulmonary disease. -- Abstract: Background: The usefulness of paired maximum inspiratory and expiratory (I/E) plain chest radiography (pCR) for diagnosis of chronic obstructive pulmonary disease (COPD) is still unclear. Objectives: We examined whether measurement of the I/E ratio using paired I/E pCR could be used for detection of airflow limitation in patients with COPD. Methods: Eighty patients with COPD (GOLD stage I = 23, stage II = 32, stage III = 15, stage IV = 10) and 34 control subjects were enrolled. The I/E ratios of frontal and lateral lung areas, and lung distance between the apex and base on pCR views were analyzed quantitatively. Pulmonary function parameters were measured at the same time. Results: The I/E ratios for the frontal lung area (1.25 ± 0.01), the lateral lung area (1.29 ± 0.01), and the lung distance (1.18 ± 0.01) were significantly (p < 0.05) reduced in COPD patients compared with controls (1.31 ± 0.02 and 1.38 ± 0.02, and 1.22 ± 0.01, respectively). The I/E ratios in frontal and lateral areas, and lung distance were significantly (p < 0.05) reduced in severe (GOLD stage III) and very severe (GOLD stage IV) COPD as compared to control subjects, although the I/E ratios did not differ significantly between severe and very severe COPD. Moreover, the I/E ratios were significantly correlated with pulmonary function parameters. Conclusions: Measurement of I/E ratios on paired I/E pCR is simple and

  8. Airflow Simulation Techniques

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    The paper describes the development in airflow simulations in rooms . The research is, as other areas of flow research, influenced by the decreasing cost of computation which seems to indicate an increased use of airflow simulation in the coming years.......The paper describes the development in airflow simulations in rooms . The research is, as other areas of flow research, influenced by the decreasing cost of computation which seems to indicate an increased use of airflow simulation in the coming years....

  9. Association of incidental emphysema with annual lung function decline and future development of airflow limitation

    Directory of Open Access Journals (Sweden)

    Koo HK

    2016-01-01

    Full Text Available Hyeon-Kyoung Koo,1 Kwang Nam Jin,2 Deog Kyeom Kim,3 Hee Soon Chung,3 Chang-Hoon Lee3,4 1Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, College of Medicine, Ilsan Paik Hospital, Inje University, Goyang-si, Gyeonggi-Do, 2Department of Radiology, Seoul Metropolitan Government – Seoul National University Boramae Medical Center, 3Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 4Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea Objectives: Emphysema is one of the prognostic factors for rapid lung function decline in patients with COPD, but the impact of incidentally detected emphysema on population without spirometric abnormalities has not been evaluated. This study aimed to determine whether emphysema detected upon computed tomography (CT screening would accelerate the rate of lung function decline and influence the possibility of future development of airflow limitation in a population without spirometric abnormalities.Materials and methods: Subjects who participated in a routine screening for health checkup and follow-up pulmonary function tests for at least 3 years between 2004 and 2010 were retrospectively enrolled. The percentage of low-attenuation area below −950 Hounsfield units (%LAA−950 was calculated automatically. A calculated value of %LAA−950 that exceeded 10% was defined as emphysema. Adjusted annual lung function decline was analyzed using random-slope, random-intercept mixed linear regression models.Results: A total of 628 healthy subjects within the normal range of spriometric values were included. Multivariable analysis showed that the emphysema group exhibited a faster decline in forced vital capacity (−33.9 versus −18.8

  10. Circulating activated innate lymphoid cells and mucosal-associated invariant T cells are associated with airflow limitation in patients with asthma

    Directory of Open Access Journals (Sweden)

    Ayako Ishimori

    2017-04-01

    Conclusions: For the first time, our data showed that activated NK cells, ILC1s, ILC2s, ILC3s, and MAIT cells were positively correlated with each other and may be associated with airflow limitation in patients with asthma.

  11. Chronic air-flow limitation does not increase respiratory epithelial permeability assessed by aerosolized solute, but smoking does

    International Nuclear Information System (INIS)

    Huchon, G.J.; Russell, J.A.; Barritault, L.G.; Lipavsky, A.; Murray, J.F.

    1984-01-01

    To determine the separate influences of smoking and severe air-flow limitation on aerosol deposition and respiratory epithelial permeability, we studied 26 normal nonsmokers, 12 smokers without airway obstruction, 12 nonsmokers with chronic obstructive pulmonary disease (COPD), and 11 smokers with COPD. We aerosolized 99mTc-labeled diethylene triamine pentaacetic acid to particles approximately 1 micron activity median aerodynamic diameter. Levels of radioactivity were plotted semilogarithmically against time to calculate clearance as percent per minute. The distribution of radioactivity was homogeneous in control subjects and in smokers, but patchy in both groups with COPD. No difference was found between clearances of the control group (1.18 +/- 0.31% min-1), and nonsmoker COPD group (1.37 +/- 0.82% min-1), whereas values in smokers without COPD (4.00 +/- 1.70% min-1) and smokers with COPD (3.62 +/- 2.88% min-1) were significantly greater than in both nonsmoking groups. We conclude that (1) small particles appear to deposit peripherally, even with severe COPD; (2) respiratory epithelial permeability is normal in nonsmokers with COPD; (3) smoking increases permeability by a mechanism unrelated to air-flow limitation

  12. Testing limits to airflow perturbation device (APD measurements

    Directory of Open Access Journals (Sweden)

    Jamshidi Shaya

    2008-10-01

    Full Text Available Abstract Background The Airflow Perturbation Device (APD is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated. Method Ten subjects between the ages of 18 and 35 were tested for each station in the experiment. The first station involved testing the effects of leaks of known sizes on APD measurements. The second station tested the use of an oronasal mask used in conjunction with the APD during nose and mouth breathing. The third station tested the effects of two different resistances added in series with the APD mouthpiece. The fourth station tested the usage of a flexible ventilator tube in conjunction with the APD. Results All leaks reduced APD resistance measurement values. Leaks represented by two 3.2 mm diameter tubes reduced measured resistance by about 10% (4.2 cmH2O·sec/L for control and 3.9 cm H2O·sec/L for the leak. This was not statistically significant. Larger leaks given by 4.8 and 6.4 mm tubes reduced measurements significantly (3.4 and 3.0 cm cmH2O·sec/L, respectively. Mouth resistance measured with a cardboard mouthpiece gave an APD measurement of 4.2 cm H2O·sec/L and mouth resistance measured with an oronasal mask was 4.5 cm H2O·sec/L; the two were not significantly different. Nose resistance measured with the oronasal mask was 7.6 cm H2O·sec/L. Adding airflow resistances of 1.12 and 2.10 cm H2O·sec/L to the breathing circuit between the mouth and APD yielded respiratory resistance values higher than the control by 0.7 and 2.0 cm H2O·sec/L. Although breathing through a 52 cm length of flexible ventilator tubing reduced the APD

  13. Airflow attenuation and bed net utilization: observations from Africa and Asia

    DEFF Research Database (Denmark)

    von Seidlein, Lorenz; Ikonomidis, Konstantin; Bruun, Rasmus

    2012-01-01

    Background/Methods Qualitative studies suggest that bed nets affect the thermal comfort of users. To understand and reduce this discomfort the effect of bed nets on temperature, humidity, and airflow was measured in rural homes in Asia and Africa, as well as in an experimental wind tunnel. Two...... discomfort is a factor limiting bed net use and open a range of architectural possibilities to overcome this limitation. Keywords: Malaria; Bed nets; Africa; Tanzania; The Gambia; Asia; Thailand; Philippines; Airflow; Temperature; Humidity; Climate...... investigators with architectural training selected 60 houses in The Gambia, Tanzania, Philippines, and Thailand. Data-loggers were used to measure indoor temperatures in hourly intervals over a 12 months period. In a subgroup of 20 houses airflow, temperature and humidity were measured at five-minute intervals...

  14. Influence of Airflow on Laboratory Storage of High Moisture Corn Stover

    Energy Technology Data Exchange (ETDEWEB)

    Lynn M. Wendt; Ian J. Bonner; Amber N. Hoover; Rachel M. Emerson; William A. Smith

    2014-04-01

    Storing high moisture biomass for bioenergy use is a reality in many areas of the country where wet harvest conditions and environmental factors prevent dry storage from being feasible. Aerobic storage of high moisture biomass leads to microbial degradation and self-heating, but oxygen limitation can aid in material preservation. To understand the influence of oxygen presence on high moisture biomass (50 %, wet basis), three airflow rates were tested on corn stover stored in laboratory reactors. Temperature, carbon dioxide production, dry matter loss, chemical composition, fungal abundance, pH, and organic acids were used to monitor the effects of airflow on storage conditions. The results of this work indicate that oxygen availability impacts both the duration of self-heating and the severity of dry matter loss. High airflow systems experienced the greatest initial rates of loss but a shortened microbially active period that limited total dry matter loss (19 %). Intermediate airflow had improved preservation in short-term storage compared to high airflow systems but accumulated the greatest dry matter loss over time (up to 27 %) as a result of an extended microbially active period. Low airflow systems displayed the best performance with the lowest rates of loss and total loss (10 %) in storage at 50 days. Total structural sugar levels of the stored material were preserved, although glucan enrichment and xylan loss were documented in the high and intermediate flow conditions. By understanding the role of oxygen availability on biomass storage performance, the requirements for high moisture storage solutions may begin to be experimentally defined.

  15. Different histological subtypes of peripheral lung cancer based on emphysema distribution in patients with both airflow limitation and CT-determined emphysema.

    Science.gov (United States)

    Shin, Beomsu; Shin, Sumin; Chung, Myung Jin; Lee, Hyun; Koh, Won-Jung; Kim, Hojoong; Park, Hye Yun

    2017-02-01

    The histological subtypes by peripheral tumor location remain uncharacterized in COPD patients with emphysema. We investigated histologic subtypes of peripheral lung cancers based on the context of heterogeneous emphysema distribution in patients with airflow limitation and CT-determined emphysema. A retrospective, cross-sectional study was conducted using data from 754 patients with airflow limitation and newly-diagnosed primary lung cancers from February 2013 to February 2015. Of these, 230 patients had emphysema, as determined by computed tomography software designed to quantify emphysema. Among the 230 patients, the most common subtype in central lesions (n=84) was squamous cell carcinoma (SCC) (n=64/84, 76%). Adenocarcinoma (ADC) was more frequently observed in peripheral lesions (n=146) than central lesions (58/146 [40%] vs. 4/84 [5%], pemphysema than emphysema areas (43/74 [58%] vs. 15/72 [21%], pemphysema areas than areas without emphysema (44/72 [61%] vs. 13/74 [18%], pemphysema, the main histological subtype of peripheral lung cancer was SCC in emphysema areas and ADC in areas without emphysema. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Room Airflows with Low Reynolds Number Effects

    DEFF Research Database (Denmark)

    Topp, Claus; Nielsen, Peter V.; Davidson, Lars

    The behaviour of room airflows under fully turbulent conditions is well known both in terms of experiments and, numerical calculations by computational fluid dynamics (CFD). For room airflows where turbulence is not fully developed though, i.e. flows at low Reynolds numbers, the existing knowledge...... is limited. It has been the objective to investigate the behaviour of a plane isothermal wall jet in a full-scale ventilated room at low Reynolds numbers, i.e. when the flow is not fully turbulent. The results are significantly different from known theory for fully turbulent flows. It was found that the jet...... constants are a strong function of the Reynolds number up to a level of Reh≈500....

  17. Underground anemotactic orientation in leaf-cutting ants: perception of airflow and experience-dependent choice of airflow direction during digging

    Science.gov (United States)

    Halboth, Florian; Roces, Flavio

    2017-10-01

    Air exchange between the large nests of Atta vollenweideri leaf-cutting ants and the environment strongly relies on a passive, wind-induced ventilation mechanism. Air moves through nest tunnels and airflow direction depends on the location of the tunnel openings on the nest mound. We hypothesized that ants might use the direction of airflow along nest tunnels as orientation cue in the context of climate control, as digging workers might prefer to broaden or to close tunnels with inflowing or outflowing air in order to regulate nest ventilation. To investigate anemotactic orientation in Atta vollenweideri, we first tested the ants' ability to perceive air movements by confronting single workers with airflow stimuli in the range 0 to 20 cm/s. Workers responded to airflow velocities ≥ 2 cm/s, and the number of ants reacting to the stimulus increased with increasing airflow speed. Second, we asked whether digging workers use airflow direction as an orientation cue. Workers were exposed to either inflow or outflow of air while digging in the nest and could subsequently choose between two digging sites providing either inflow or outflow of air, respectively. Workers significantly chose the side with the same airflow direction they experienced before. When no airflow was present during initial digging, workers showed no preference for airflow directions. Workers developed preferences for airflow direction only after previous exposure to a given airflow direction. We suggest that experience-modified anemotaxis might help leaf-cutting ants spatially organize their digging activity inside the nest during tasks related to climate control.

  18. Relationship of airway dimensions with airflow limitation or lung volumes in chronic obstructive pulmonary disease (COPD

    Directory of Open Access Journals (Sweden)

    Masaru Hasegawa

    2006-12-01

    Full Text Available We have recently developed new software to obtain longitudinal images and accurate short axis images of airways with an inner diameter > 2 mm located anywhere in the lung, using curved multiplanar reconstruction. Using this software, we demonstrated in patients with COPD that FEV1 (%predicted was highly correlated with airway dimensions and the correlation coefficients improved as the airway became smaller in size (3. In this study, our aims are to further confirm the significant relationship between airway dimensions and airflow limitation in larger number of subjects, and to examine the relationship of airway dimensions with lung volumes in 95 patients with COPD (stage 0, 10; stage I, 23; stage II, 35; stage III, 24; stage IV, 3. We analyzed the airway dimensions from the 3rd to the 6th generations of the apical bronchus (B1 of the right upper lobe and the anterior basal bronchus (B8 of the right lower lobe. Lung volumes were measured by the helium closed circuit method. Both airway luminal area (Ai and wall area percent (WA% of all the generations, except a few, from the two bronchi were significantly correlated with RV and RV/TLC, but not with TLC or FRC. More importantly, the correlation coefficients (r between airway dimensions and RV/TLC improved as the airways became smaller in size from the 3rd to 6th generations in both bronchi (r = –0.483, –0482, –0.553, –0.624 for Ai of B8; r = 0.316, 0.380, 0.499, 0.551 for WA% of B8. These findings provide further evidence that distal (small airways rather than proximal (large airways are the determinants for airflow limitation in COPD.

  19. Lung sound intensity in patients with emphysema and in normal subjects at standardised airflows.

    Science.gov (United States)

    Schreur, H J; Sterk, P J; Vanderschoot, J; van Klink, H C; van Vollenhoven, E; Dijkman, J H

    1992-01-01

    BACKGROUND: A common auscultatory finding in pulmonary emphysema is a reduction of lung sounds. This might be due to a reduction in the generation of sounds due to the accompanying airflow limitation or to poor transmission of sounds due to destruction of parenchyma. Lung sound intensity was investigated in normal and emphysematous subjects in relation to airflow. METHODS: Eight normal men (45-63 years, FEV1 79-126% predicted) and nine men with severe emphysema (50-70 years, FEV1 14-63% predicted) participated in the study. Emphysema was diagnosed according to pulmonary history, results of lung function tests, and radiographic criteria. All subjects underwent phonopneumography during standardised breathing manoeuvres between 0.5 and 2 1 below total lung capacity with inspiratory and expiratory target airflows of 2 and 1 l/s respectively during 50 seconds. The synchronous measurements included airflow at the mouth and lung volume changes, and lung sounds at four locations on the right chest wall. For each microphone airflow dependent power spectra were computed by using fast Fourier transformation. Lung sound intensity was expressed as log power (in dB) at 200 Hz at inspiratory flow rates of 1 and 2 l/s and at an expiratory flow rate of 1 l/s. RESULTS: Lung sound intensity was well repeatable on two separate days, the intraclass correlation coefficient ranging from 0.77 to 0.94 between the four microphones. The intensity was strongly influenced by microphone location and airflow. There was, however, no significant difference in lung sound intensity at any flow rate between the normal and the emphysema group. CONCLUSION: Airflow standardised lung sound intensity does not differ between normal and emphysematous subjects. This suggests that the auscultatory finding of diminished breath sounds during the regular physical examination in patients with emphysema is due predominantly to airflow limitation. Images PMID:1440459

  20. Temperature-controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflow.

    Science.gov (United States)

    Alsved, M; Civilis, A; Ekolind, P; Tammelin, A; Andersson, A Erichsen; Jakobsson, J; Svensson, T; Ramstorp, M; Sadrizadeh, S; Larsson, P-A; Bohgard, M; Šantl-Temkiv, T; Löndahl, J

    2018-02-01

    To evaluate three types of ventilation systems for operating rooms with respect to air cleanliness [in colony-forming units (cfu/m 3 )], energy consumption and comfort of working environment (noise and draught) as reported by surgical team members. Two commonly used ventilation systems, vertical laminar airflow (LAF) and turbulent mixed airflow (TMA), were compared with a newly developed ventilation technique, temperature-controlled airflow (T c AF). The cfu concentrations were measured at three locations in an operating room during 45 orthopaedic procedures: close to the wound (draught. T c AF and LAF remove bacteria more efficiently from the air than TMA, especially close to the wound and at the instrument table. Like LAF, the new T c AF ventilation system maintained very low levels of cfu in the air, but T c AF used substantially less energy and provided a more comfortable working environment than LAF. This enables energy savings with preserved air quality. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Prevalence and determinants of airflow limitation in urban and rural children exposed to cooking fuels in South-East Nigeria.

    Science.gov (United States)

    Oguonu, Tagbo; Obumneme-Anyim, Ijeoma N; Eze, Joy N; Ayuk, Adaeze C; Okoli, Chinyere V; Ndu, Ikenna K

    2018-03-15

    Background Biofuels and other cooking fuels are used in households in low- and middle-income countries. Aim To investigate the impact of cooking fuels on lung function in children in urban and rural households in South-East Nigeria. Methods The multi-stage sampling method was used to enroll children exposed to cooking fuel in the communities. Lung function values FEV1, FVC and the FEV1/FVC ratio, were measured with ndd EasyOne R spirometer. Airflow limitation was determined with FEV1/FVC Z-score values at -1.64 as the lower limit of normal (LLN5). The Global Lung Function Initiative 2012 software was used to calculate the lung function indices. Results The median age (range) of the 912 children enrolled was 10.6 years (6-18). Altogether, 468 (51.6%) children lived in rural areas. Seven hundred and thirty-seven (80.7%) were directly exposed to cooking fuels (418/737, 56.5% in rural areas). Wood and kerosene were the dominant fuels in rural and urban households. The respective mean Z-scores of the exposed children in rural and urban were zFEV1 -0.62, FVC -0.21, FEV1/FVC -0.83 and zFEV1 -0.57, zFVC -0.14, FEV1/FVC -0.75. Few (5.2%, 38/737) of the children had airflow limitation. Most of them (60.5%, 25/38) lived in the rural community; the lowest FEV1/FVC Z-scores were those of exposed to a combination of fuels. Conclusion Exposure to cooking fuels affects lung function in children with airway limitation in a small proportion, Control measures are advocated to reduce the morbidity related to cooking fuels exposure.

  2. Visualization of airflow growing soap bubbles

    Science.gov (United States)

    Al Rahbi, Hamood; Bock, Matthew; Ryu, Sangjin

    2016-11-01

    Visualizing airflow inside growing soap bubbles can answer questions regarding the fluid dynamics of soap bubble blowing, which is a model system for flows with a gas-liquid-gas interface. Also, understanding the soap bubble blowing process is practical because it can contribute to controlling industrial processes similar to soap bubble blowing. In this study, we visualized airflow which grows soap bubbles using the smoke wire technique to understand how airflow blows soap bubbles. The soap bubble blower setup was built to mimic the human blowing process of soap bubbles, which consists of a blower, a nozzle and a bubble ring. The smoke wire was placed between the nozzle and the bubble ring, and smoke-visualized airflow was captured using a high speed camera. Our visualization shows how air jet flows into the growing soap bubble on the ring and how the airflow interacts with the soap film of growing bubble.

  3. Comparison of pulmonary function in patients with COPD, asthma-COPD overlap syndrome, and asthma with airflow limitation.

    Science.gov (United States)

    Kitaguchi, Yoshiaki; Yasuo, Masanori; Hanaoka, Masayuki

    2016-01-01

    This study was conducted in order to investigate the differences in the respiratory physiology of patients with chronic obstructive pulmonary disease (COPD), asthma-COPD overlap syndrome (ACOS), and asthma with airflow limitation (asthma FL(+)). The medical records for a series of all stable patients with persistent airflow limitation due to COPD, ACOS, or asthma were retrospectively reviewed and divided into the COPD group (n=118), the ACOS group (n=32), and the asthma FL(+) group (n=27). All the patients underwent chest high-resolution computed tomography (HRCT) and pulmonary function tests, including respiratory impedance. The low attenuation area score on chest HRCT was significantly higher in the COPD group than in the ACOS group (9.52±0.76 vs 5.09±1.16, Pbronchial wall thickening on chest HRCT was significantly higher in the asthma FL(+) group than in the COPD group (55.6% vs 25.0%, P<0.01). In pulmonary function, forced expiratory volume in 1 second (FEV1) and peak expiratory flow rate were significantly higher in the asthma FL(+) group than in the ACOS group (76.28%±2.54% predicted vs 63.43%±3.22% predicted, P<0.05 and 74.40%±3.16% predicted vs 61.08%±3.54% predicted, P<0.05, respectively). Although residual volume was significantly lower in the asthma FL(+) group than in the COPD group (112.05%±4.34% predicted vs 137.38%±3.43% predicted, P<0.01) and the ACOS group (112.05%±4.34% predicted vs148.46%±6.25% predicted, P<0.01), there were no significant differences in functional residual capacity or total lung capacity. The increase in FEV1 in response to short-acting β2-agonists was significantly greater in the ACOS group than in the COPD group (229±29 mL vs 72±10 mL, P<0.01) and the asthma FL(+) group (229±29 mL vs 153±21 mL, P<0.05). Regarding respiratory impedance, resistance at 5 Hz and resistance at 20 Hz, which are oscillatory parameters of respiratory resistance, were significantly higher in the asthma FL(+) group than in the COPD group

  4. Proportion and clinical characteristics of non-asthmatic non-smokers among adults with airflow obstruction.

    Directory of Open Access Journals (Sweden)

    Hiroto Takiguchi

    Full Text Available Chronic obstructive pulmonary disease (COPD mainly develops after long-term exposure to cigarette or biomass fuel smoke, but also occurs in non-smokers with or without a history of asthma. We investigated the proportion and clinical characteristics of non-smokers among middle-aged to elderly subjects with airflow obstruction.We retrospectively analyzed 1,892 subjects aged 40-89 years who underwent routine preoperative spirometry at a tertiary university hospital in Japan. Airflow obstruction was defined as a forced expiratory volume in 1 second (FEV1/forced vital capacity < 0.7 or as the lower limit of the normal.Among 323 patients presenting with FEV1/forced vital capacity < 0.7, 43 had asthma and 280 did not. Among the non-asthmatic patients with airflow obstruction, 94 (34% were non-smokers. A larger number of women than men with airflow obstruction had asthma (26% vs. 7.6%, p < 0.001, or were non-smokers among non-asthmatics (72% vs. 20%, p < 0.001. Non-asthmatic non-smokers, rather than non-asthmatic smokers, asthmatic non-smokers, and asthmatic smokers, exhibited better pulmonary function (median FEV1: 79% of predicted FEV1 vs. 73%, 69%, and 66%, respectively, p = 0.005 and less dyspnea on exertion (1% vs. 12%, 12%, and 28%, respectively, p = 0.001. Pulmonary emphysema on thoracic computed tomography was less common in non-smokers (p < 0.001. Using the lower limit of the normal to define airflow obstruction yielded similar results.There are a substantial number of non-smokers with airflow obstruction compatible with COPD in Japan. In this study, airflow obstruction in non-smokers was more common in women and likelier to result in mild functional and pathological abnormalities than in smokers. Further studies are warranted to investigate the long-term prognosis and appropriate management of this population in developed countries, especially in women.

  5. Effects of blood lead levels on airflow limitations in Korean adults: Findings from the 5th KNHNES 2011

    International Nuclear Information System (INIS)

    Chung, Hye Kyung; Chang, Yoon Soo; Ahn, Chul Woo

    2015-01-01

    This study aimed to examine whether blood levels of heavy metals, such as lead, mercury and cadmium, are related with pulmonary function in Korean adults. This investigation included 870 Korean adults (≥40 years) who received pulmonary function testing in the Korea National Health and Nutrition Examination Survey (KNHANES) V-2, 2011. Data of blood levels of heavy metals, pulmonary function tests and anthropometric measurements were acquired. Blood lead levels showed inverse correlations with the FEV 1 /FVC ratio before (r=−0.276, p<0.001) and after adjustment of multiple compounding factors (r=−0.115, p=0.001). A logistic multiple regression analysis revealed that blood lead levels were a significant influencing factor for the FEV 1 /FVC ratio (β=−0.017, p=0.001, adjusted R 2 =0.267). The odds ratios (ORs) for the FEV 1 /FVC ratio were significantly lower in the highest tertile group of the blood lead levels than in the lowest tertile group in Model 1 (OR=0.007, 95% CI=0.000−0.329) and Model 2 (OR=0.006, 95% CI=0.000−0.286). These findings imply that environmental exposure to lead might be an important factor that may cause airflow limitations in Korean adults. - Highlights: • Blood lead levels showed inverse correlations with the FEV 1 /FVC ratio. • Blood lead level was a significant influencing factor for the FEV 1 /FVC ratio. • ORs for FEV 1 /FVC were lower in the highest blood lead group than in the lowest group. • Environmental exposure to lead might be an important factor for airflow limitations

  6. Measured Performance of a Varied Airflow Small-Diameter Duct System

    Energy Technology Data Exchange (ETDEWEB)

    Poerschke, Andrew [IBACOS, Inc., Pittsburgh, PA (United States)

    2017-03-01

    This study tests the performance of a variable airflow small-diameter duct heating, ventilation, and air conditioning (HVAC) system in a new construction unoccupied low-load test house in Pittsburgh, Pennsylvania. The duct system was installed entirely in conditioned space and was operated from the winter through summer seasons. Measurements were collected on the in-room temperatures and energy consumed by the air handler and heat pump unit. Operation modes with three different volumes of airflow were compared to determine the ideal airflow scenario that maximizes room-to-room thermal uniformity while minimizing fan energy consumption. Black felt infrared imagery was used as a measure of diffuser throw and in-room air mixing. Measured results indicate the small-diameter, high velocity airflow system can provide comfort under some conditions. Solar heat gains resulted in southern rooms drifting beyond acceptable temperature limits. Insufficient airflow to some bedrooms also resulted in periods of potential discomfort. Homebuilders or HVAC contractors can use these results to assess whether this space conditioning strategy is an attractive alternative to a traditional duct system. The team performed a cost analysis of two duct system configurations: (1) a conventional diameter and velocity duct system, and (2) the small-diameter duct system. This work applies to both new and retrofit homes that have achieved a low heating and cooling density either by energy conservation or by operation in a mild climate with few heating or cooling degree days. Guidance is provided on cost trade-offs between the conventional duct system and the small-diameter duct system.

  7. Measured Performance of a Varied Airflow Small-Diameter Duct System

    Energy Technology Data Exchange (ETDEWEB)

    Poerschke, Andrew [IBACOS, Inc., Pittsburgh, PA (United States)

    2017-03-16

    This study tests the performance of a variable airflow small-diameter duct heating, ventilation, and air conditioning (HVAC) system in a new construction unoccupied low-load test house in Pittsburgh, Pennsylvania. The duct system was installed entirely in conditioned space and was operated from the winter through summer seasons. Measurements were collected on the in-room temperatures and energy consumed by the air handler and heat pump unit. Operation modes with three different volumes of airflow were compared to determine the ideal airflow scenario that maximizes room-to-room thermal uniformity while minimizing fan energy consumption. Black felt infrared imagery was used as a measure of diffuser throw and in-room air mixing. Measured results indicate the small-diameter, high velocity airflow system can provide comfort under some conditions. Solar heat gains resulted in southern rooms drifting beyond acceptable temperature limits. Insufficient airflow to some bedrooms also resulted in periods of potential discomfort. Homebuilders or HVAC contractors can use these results to assess whether this space conditioning strategy is an attractive alternative to a traditional duct system. The team performed a cost analysis of two duct system configurations: (1) a conventional diameter and velocity duct system, and (2) the small-diameter duct system. This work applies to both new and retrofit homes that have achieved a low heating and cooling density either by energy conservation or by operation in a mild climate with few heating or cooling degree days. Guidance is provided on cost trade-offs between the conventional duct system and the small-diameter duct system.

  8. Estimation of the site of wheezes in pulmonary emphysema: airflow simulation study by the use of A 4D lung model.

    Science.gov (United States)

    Kitaoka, Hiroko; Cok, Salim

    2013-01-01

    Adventitious lung sounds in pulmonary emphysema, wheezes, are continuous musical sounds during expiration with 400 Hz or more. The textbook tells that expiratory airflow limitation in emphysema occurs at the peripheral airways and that wheezes are generated there. We have recently proposed a novel hypothesis based on image analysis and theoretical consideration that expiratory airflow limitation in emphysema occurs at the intra-mediastinal airway (trachea, main bronchi, and right lobar bronchi) due to compression by overinflated lungs. We performed expiratory airflow simulation by the use of a 4D finite element lung model, and found periodical vortex release with 300-900 Hz at the end of protrusion of the the tracheal posterior wall. Relationship between the peak frequency of pressure fluctuation and airflow velocity was in agreement with Strahal's law either in normal or emphysematous condition. Contrarily, airflow simulation in a small bronchus (1.5 mm in diameter) indicated no apparent periodic vortex release.

  9. Comparison of pulmonary function in patients with COPD, asthma-COPD overlap syndrome, and asthma with airflow limitation

    Directory of Open Access Journals (Sweden)

    Kitaguchi Y

    2016-05-01

    Full Text Available Yoshiaki Kitaguchi, Masanori Yasuo, Masayuki Hanaoka First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan Background: This study was conducted in order to investigate the differences in the respiratory physiology of patients with chronic obstructive pulmonary disease (COPD, asthma-COPD overlap syndrome (ACOS, and asthma with airflow limitation (asthma FL+. Methods: The medical records for a series of all stable patients with persistent airflow limitation due to COPD, ACOS, or asthma were retrospectively reviewed and divided into the COPD group (n=118, the ACOS group (n=32, and the asthma FL+ group (n=27. All the patients underwent chest high-resolution computed tomography (HRCT and pulmonary function tests, including respiratory impedance. Results: The low attenuation area score on chest HRCT was significantly higher in the COPD group than in the ACOS group (9.52±0.76 vs 5.09±1.16, P<0.01. The prevalence of bronchial wall thickening on chest HRCT was significantly higher in the asthma FL+ group than in the COPD group (55.6% vs 25.0%, P<0.01. In pulmonary function, forced expiratory volume in 1 second (FEV1 and peak expiratory flow rate were significantly higher in the asthma FL+ group than in the ACOS group (76.28%±2.54% predicted vs 63.43%±3.22% predicted, P<0.05 and 74.40%±3.16% predicted vs 61.08%±3.54% predicted, P<0.05, respectively. Although residual volume was significantly lower in the asthma FL+ group than in the COPD group (112.05%±4.34% predicted vs 137.38%±3.43% predicted, P<0.01 and the ACOS group (112.05%±4.34% predicted vs148.46%±6.25% predicted, P<0.01, there were no significant differences in functional residual capacity or total lung capacity. The increase in FEV1 in response to short-acting ß2-agonists was significantly greater in the ACOS group than in the COPD group (229±29 mL vs 72±10 mL, P<0.01 and the asthma FL+ group (229±29 mL vs 153±21 mL, P<0.05. Regarding

  10. Occupational exposure to pesticides are associated with fixed airflow obstruction in middle-age.

    Science.gov (United States)

    Alif, Sheikh M; Dharmage, Shyamali C; Benke, Geza; Dennekamp, Martine; Burgess, John A; Perret, Jennifer L; Lodge, Caroline J; Morrison, Stephen; Johns, David Peter; Giles, Graham G; Gurrin, Lyle C; Thomas, Paul S; Hopper, John Llewelyn; Wood-Baker, Richard; Thompson, Bruce R; Feather, Iain H; Vermeulen, Roel; Kromhout, Hans; Walters, E Haydn; Abramson, Michael J; Matheson, Melanie Claire

    2017-11-01

    Population-based studies have found evidence of a relationship between occupational exposures and Chronic Obstructive Pulmonary Disease (COPD), but these studies are limited by the use of prebronchodilator spirometry. Establishing this link using postbronchodilator is critical, because occupational exposures are a modifiable risk factor for COPD. To investigate the associations between occupational exposures and fixed airflow obstruction using postbronchodilator spirometry. One thousand three hundred and thirty-five participants were included from 2002 to 2008 follow-up of the Tasmanian Longitudinal Health Study (TAHS). Spirometry was performed and lifetime work history calendars were used to collect occupational history. ALOHA plus Job Exposure Matrix was used to assign occupational exposure, and defined as ever exposed and cumulative exposure unit (EU)-years. Fixed airflow obstruction was defined by postbronchodilator FEV 1 /FVC biological dust (relative risk (RR)=1.58, 95% CI 1.01 to 2.48), pesticides (RR=1.74,95% CI 1.00 to 3.07) and herbicides (RR=2.09,95% CI 1.18 to 3.70) were associated with fixed airflow obstruction. Cumulative EU-years to all pesticides (RR=1.11,95% CI 1.00 to 1.25) and herbicides (RR=1.15,95% CI 1.00 to 1.32) were also associated with fixed airflow obstruction. In addition, all pesticides exposure was consistently associated with chronic bronchitis and symptoms that are consistent with airflow obstruction. Ever exposure to mineral dust, gases/fumes and vapours, gases, dust or fumes were only associated with fixed airflow obstruction in non-asthmatics only. Pesticides and herbicides exposures were associated with fixed airflow obstruction and chronic bronchitis. Biological dust exposure was also associated with fixed airflow obstruction in non-asthmatics. Minimising occupational exposure to these agents may help to reduce the burden of COPD. © Article author(s) (or their employer(s) unless otherwise stated in the text of the

  11. Irreversible social change

    NARCIS (Netherlands)

    Pols, A.J.K.; Romijn, H.A.; Collste, G.; Reuter, L.

    2014-01-01

    In this paper we evaluate how irreversible social change should be evaluated from an ethical perspective. First; we analyse the notion of irreversibility in general terms. We define a general notion of what makes a change irreversible; drawing on discussions in ecology and economics. This notion is

  12. Airflow obstruction in young adults in Canada

    DEFF Research Database (Denmark)

    Al-Hazmi, Manal; Wooldrage, Kate; Anthonisen, Nicholas R.

    2007-01-01

    OBJECTIVE: Airflow obstruction is relatively uncommon in young adults, and may indicate potential for the development of progressive disease. The objective of the present study was to enumerate and characterize airflow obstruction in a random sample of Canadians aged 20 to 44 years. SETTING: The ...

  13. Airflow Pattern Genereated by Three Air Diffusers

    DEFF Research Database (Denmark)

    Olmedo, Inés; Nielsen, Peter V.; de Adana, Manuel Ruiz

    The correct description of air diffusers plays a crucial role in the CFD predictions of the airflow pattern into a room. The numerical simulation of air distribution in an indoor space is challenging because of the complicated airflow pattern generated. An experimental study has been carried out...... in a full scale test room, 4.10 m (length), 3.20 m (width), and 2.70 m (height), in order to take velocity measurements of the airflow pattern generated by three different air diffusers: displacement, mixing and a low impulse diffuser. Smoke visualization has been developed to determine the direction...

  14. Irreversible thermodynamic analysis and application for molecular heat engines

    Science.gov (United States)

    Lucia, Umberto; Açıkkalp, Emin

    2017-09-01

    Is there a link between the macroscopic approach to irreversibility and microscopic behaviour of the systems? Consumption of free energy keeps the system away from a stable equilibrium. Entropy generation results from the redistribution of energy, momentum, mass and charge. This concept represents the essence of the thermodynamic approach to irreversibility. Irreversibility is the result of the interaction between systems and their environment. The aim of this paper is to determine lost works in a molecular engine and compare results with macro (classical) heat engines. Firstly, irreversible thermodynamics are reviewed for macro and molecular cycles. Secondly, irreversible thermodynamics approaches are applied for a quantum heat engine with -1/2 spin system. Finally, lost works are determined for considered system and results show that macro and molecular heat engines obey same limitations. Moreover, a quantum thermodynamic approach is suggested in order to explain the results previously obtained from an atomic viewpoint.

  15. Airflow Pattern Generated by Three Air Diffusers

    DEFF Research Database (Denmark)

    Olmedo, Inés; Nielsen, Peter V.; Ruiz de Adana, Manuel

    2011-01-01

    The correct description of air diffusers plays a crucial role in the CFD predictions of the airflow pattern into a room. The numerical simulation of air distribution in an indoor space is challenging because of the complicated airflow pattern generated. Many authors have developed simplified geom...

  16. Awareness and prevalence of acute mountain sickness and prevalence of obstructive airflow limitation among Nepalese porters: A cross-sectional study in Khumbu Valley, Nepal

    OpenAIRE

    Parajuli, Ranjan

    2009-01-01

    Background: Acute mountain sickness is a major public health problem in high altitudes. Similarly, anecdotal evidence suggests that there is high prevalence of tobacco smoking among this group though prevalence of obstructive airflow limitation is not known. Objectives: The main aims of the study were to measure the awareness of AMS and report the prevalence of AMS and obstructive lung diseases in high altitude Nepalese porters. Setting: This study was done with bases in Namche Bazaar (...

  17. COMPUTATIONAL MODELING OF AIRFLOW IN NONREGULAR SHAPED CHANNELS

    Directory of Open Access Journals (Sweden)

    A. A. Voronin

    2013-05-01

    Full Text Available The basic approaches to computational modeling of airflow in the human nasal cavity are analyzed. Different models of turbulent flow which may be used in order to calculate air velocity and pressure are discussed. Experimental measurement results of airflow temperature are illustrated. Geometrical model of human nasal cavity reconstructed from computer-aided tomography scans and numerical simulation results of airflow inside this model are also given. Spatial distributions of velocity and temperature for inhaled and exhaled air are shown.

  18. Relationship of airflow limitation severity with work productivity reduction and sick leave in a Japanese working population

    Directory of Open Access Journals (Sweden)

    Onoue A

    2016-03-01

    Full Text Available Ayumi Onoue,1 Hisamitsu Omori,1 Takahiko Katoh,2 Kenichi Kubota,3 Yoshio Nonami,3 Yasuhiro Ogata,3 Hiromasa Inoue4 1Department of Biomedical Laboratory Sciences, 2Department of Public Health, Faculty of Life Sciences, Kumamoto University, 3Japanese Red Cross Kumamoto Health Care Center, Kumamoto, 4Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan Background: The aim of this study was to reveal the association between airflow limitation (AL severity and reduction with work productivity as well as use of sick leave among Japanese workers.Methods: This cross-sectional study included 1,378 workers who underwent a lung function test during a health checkup at the Japanese Red Cross Kumamoto Health Care Center. AL was defined as forced expiratory volume in 1 second/forced vital capacity of <0.7. Workers completed a questionnaire on productivity loss at work and sick leave. The quality and quantity of productivity loss at work were measured on a ten-point scale indicating how much work was actually performed on the previous workday. Participants were asked how many days in the past 12 months they were unable to work because of health problems. Logistic regression analysis was used to assess the associations between AL severity and the quality and quantity of productivity loss at work as well as use of sick leave.Results: Compared with workers without AL, workers with moderate-to-severe AL showed a significant productivity loss (quality: odds ratio [OR] =2.04, 95% confidence interval [CI]: 1.12–3.71, P=0.02 and quantity: OR =2.19, 95% CI: 1.20–4.00, P=0.011 and use of sick leave (OR =2.69, 95% CI: 1.33–5.44, P=0.006 after adjusting for sex, age, body mass index, smoking status, hypertension, hyperglycemia, dyslipidemia, sleep duration, work hours per day, and workplace smoking environment.Conclusion: AL severity was significantly associated with work productivity loss and use

  19. Transition to Clean Capital, Irreversible Investment and Stranded Assets

    OpenAIRE

    Rozenberg, Julie; Vogt-Schilb, Adrien; Hallegatte, Stephane

    2014-01-01

    This paper uses a Ramsey model with two types of capital to analyze the optimal transition to clean capital when polluting investment is irreversible. The cost of climate mitigation decomposes as a technical cost of using clean instead of polluting capital and a transition cost from the irreversibility of pre-existing polluting capital. With a carbon price, the transition cost can be limit...

  20. Contamination control in HVAC systems for aseptic processing area. Part I: Case study of the airflow velocity in a unidirectional airflow workstation with computational fluid dynamics.

    Science.gov (United States)

    Ogawa, M

    2000-01-01

    A unidirectional airflow workstation for processing a sterile pharmaceutical product is required to be "Grade A," according to EU-GMP and WHO-GMP. These regulations have employed the wording of "laminar airflow" for unidirectional airflow, with an unclear definition given. This seems to have allowed many reports to describe discussion of airflow velocity only. The guidance values as to the velocity are expressed in various words of 90 ft/min, 0.45 m/sec, 0.3 m/sec, +/- 20%, or "homogeneous air speed." It has been also little clarified how variation in airflow velocity gives influences on contamination control of a workstation working with varying key characteristics, such as ceiling height, internal heat load, internal particle generation, etc. The present author has revealed following points from a case study using Computational Fluid Dynamics: the airflow characteristic in Grade A area shows no significant changes with varying the velocity of supplied airflow, and the particles generated from the operator will be exhausted outside Grade A area without contamination.

  1. Low-airflow drying of fungicide-treated shelled corn

    International Nuclear Information System (INIS)

    Peterson, W.H.; Benson, P.W.

    1993-02-01

    Approved fungicides inhibit mold growth in shelled corn and allow for longer, natural-air drying. The longer drying periods permit lower than-normal airflows and smaller power units, thus reducing electrical demands on utilities in corn-producing states. Researchers placed approximately 67 m 3 (1900 bu) of one variety of shelled corn at approximately 24% moisture in each of five equally sized storage bins. They partitioned each bin vertically and filled one half of each bin with fungicide-treated corn and one half with untreated corn. Each of four bins used a different airflow. A fifth bin used the lowest of the four airflows but was equipped to capture and use solar energy. All corn dried rapidly with resulting good quality. The percentage of damaged kernels was significantly higher for untreated than for treated corn. The energy required for the lowest airflow system was approximately one half of that required for the higher, more traditional airflows. Because of lower-than-normal airflows, the electrical demand on the utility is approximately one fourth as great as that imposed when the higher, more traditional natural-air systems are used. The 1991 corn growing and drying seasons were unusual in central Illinois, the site of the study. Both harvest and drying occurred several weeks ahead of schedule. Additional work is needed to verify that findings hold true during more-normal Midwest corn growing and drying seasons; the investigators predict that they will. It should be noted that the fungicide used in this study has not yet been approved for widespread use in drying corn

  2. Irreversible Local Markov Chains with Rapid Convergence towards Equilibrium

    Science.gov (United States)

    Kapfer, Sebastian C.; Krauth, Werner

    2017-12-01

    We study the continuous one-dimensional hard-sphere model and present irreversible local Markov chains that mix on faster time scales than the reversible heat bath or Metropolis algorithms. The mixing time scales appear to fall into two distinct universality classes, both faster than for reversible local Markov chains. The event-chain algorithm, the infinitesimal limit of one of these Markov chains, belongs to the class presenting the fastest decay. For the lattice-gas limit of the hard-sphere model, reversible local Markov chains correspond to the symmetric simple exclusion process (SEP) with periodic boundary conditions. The two universality classes for irreversible Markov chains are realized by the totally asymmetric SEP (TASEP), and by a faster variant (lifted TASEP) that we propose here. We discuss how our irreversible hard-sphere Markov chains generalize to arbitrary repulsive pair interactions and carry over to higher dimensions through the concept of lifted Markov chains and the recently introduced factorized Metropolis acceptance rule.

  3. Integration of a Multizone Airflow Model into a Thermal simulation Program

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Sørensen, Karl Grau; Heiselberg, Per

    2007-01-01

    An existing computer model for dynamic hygrothermal analysis of buildings has been extended with a multizone airflow model based on loop equations to account for the coupled thermal and airflow in natural and hybrid ventilated buildings.......An existing computer model for dynamic hygrothermal analysis of buildings has been extended with a multizone airflow model based on loop equations to account for the coupled thermal and airflow in natural and hybrid ventilated buildings....

  4. Pitot-tube flowmeter for quantification of airflow during sleep

    International Nuclear Information System (INIS)

    Kirkness, J P; McGinley, B M; Schwartz, A R; Smith, P L; Patil, S P; Schneider, H; Verma, M; Wheatley, J R; Amis, T C; Erlacher, M

    2011-01-01

    The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1–4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H 2 O L –1 s –1 over the airflow rates of 10 to 50 L min −1 . (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumtachograph signal a (β 1 = 1.08 V L −1 s −1 ; β 0 = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow amplitude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph

  5. Pitot-tube flowmeter for quantification of airflow during sleep.

    Science.gov (United States)

    Kirkness, J P; Verma, M; McGinley, B M; Erlacher, M; Schwartz, A R; Smith, P L; Wheatley, J R; Patil, S P; Amis, T C; Schneider, H

    2011-02-01

    The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1-4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H(2)O L(-1) s(-1) over the airflow rates of 10 to 50 L min(-1). (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumotachograph signal a (β(1) = 1.08 V L(-1) s(-1); β(0) = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow amplitude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph-measured airflow. Our data

  6. Investigation of non-uniform airflow signal oscillation during high frequency chest compression

    Directory of Open Access Journals (Sweden)

    Lee Jongwon

    2005-05-01

    Full Text Available Abstract Background High frequency chest compression (HFCC is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. Methods The computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations. Results and discussion We could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system. Conclusion We found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance.

  7. Airflow patterns in complex workplaces

    International Nuclear Information System (INIS)

    Mishima, J.; Selby, J.M.; Lynch, T.P.; Langer, G.; Vallario, E.J.

    1987-01-01

    There are many considerations in obtaining an accurate evaluation of aerosols. One aspect that has been neglected is the study of airflow patterns within the workplace. In many nuclear facilities, the operations performed required extensive equipment (e.g., glove boxes, piping) that create complex arrangements of physical barriers to flow. To provide samples of the airborne materials, particularly particles, knowledge of these complex airflow patterns is required for sampler placement. Recent studies have shown that materials introduced into the air flow within a workplace act as plumes embedded in major airflow streams. Portions of the plumes can recycle through the ventilated area, be lost to dead air pockets, or exhaust through unusual, unexpected outlets. Unusual flow patterns are observed even in relatively uncomplicated arrangements of equipment. This behavior must be factored into sampling/monitoring programs for evaluation of the airborne hazard to personnel within the workplace consistent with the objective of the program. Other factors that also must be considered to provide valid samples of airborne particulate materials are objectives of the sampling program, characteristics of the airborne particulate materials, nonsegregatory transport for the extracted materials, and requirements for the measurement techniques used

  8. New CFD tools to evaluate nasal airflow.

    Science.gov (United States)

    Burgos, M A; Sanmiguel-Rojas, E; Del Pino, C; Sevilla-García, M A; Esteban-Ortega, F

    2017-08-01

    Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND ® only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow. In addition, the user-friendly environment NOSELAND ® helps the medical assessment significantly in the post-processing phase with dynamic reports using a 3D endoscopic view. Specialists in Rhinology have been asked for a more intuitive, simple, powerful CFD software to offer more quality and precision in their work to evaluate the nasal airflow. We present MECOMLAND ® and NOSELAND ® which have all the expected characteristics to fulfil this demand and offer a proper assessment with the maximum of quality plus safety for the patient. These programs represent a non-invasive, low-cost (as the CT scan is already performed in every patient) alternative for the functional study of the difficult rhinologic case. To validate the software, we studied two groups of patients from the Ear Nose Throat clinic, a first group with normal noses and a second group presenting septal deviations. Wall shear stresses are lower in the cases of normal noses in comparison with those for septal deviation. Besides, velocity field distributions, pressure drop between nasopharynx and the ambient, and flow rates in each nostril were different among the nasal cavities in the two groups. These software modules open up a promising future to simulate the nasal airflow behaviour in virtual surgery intervention scenarios under different pressure or

  9. Airflow Patterns In Nuclear Workplace - Computer Simulation And Qualitative Tests

    International Nuclear Information System (INIS)

    Haim, M.; Szanto, M.; Weiss, Y.; Kravchick, T.; Levinson, S.; German, U.

    1999-01-01

    Concentration of airborne radioactive materials inside a room can vary widely from one location to another, sometimes by orders of magnitude even for locations that are relatively close. Inappropriately placed samplers can give misleading results and. therefore, the location of air samplers is important. Proper placement of samplers cannot be determined simply by observing the position of room air supply and exhaust vents. Airflow studies, such as the release of smoke aerosols, should be used. The significance of airflow pattern studies depends on the purpose of sampling - for estimating worker intakes, warning of high concentrations. defacing airborne radioactive areas, testing for confinement of sealed radioactive materials. etc. When sampling air in rooms with complex airflow patterns, it may be useful to use qualitative airflow studies with smoke tubes, smoke candles or isostatic bubbles. The U.S. Nuclear Regulatory Commission - Regulatory Guide 8.25 [1]. suggests that an airflow study should be conducted after any changes at work area including changes in the setup of work areas, ventilation system changes, etc. The present work presents an airflow patterns study conducted in a typical room using two methods: a computer simulation and a qualitative test using a smoke tube

  10. How to account for irreversibility in integrated assessment of climate change?

    International Nuclear Information System (INIS)

    Ha Duong, M.

    1998-04-01

    How to account for irreversibility in integrated assessment of climate change? This Ph. D. thesis in Economics balances discounting, technical progress and the inertia of existing capital stock against uncertainty and the inertia of socio-economic systems to examine the issue of near term limitations of greenhouse gases emissions. After a general overview in chapter 2, and a more historical presentation of the debates in chapter 3, chapter 4 proceeds to review a large number of integrated assessment models. Chapter 5 introduces a Model on the Dynamics of Inertia and Adaptability of energy systems: DIAM, used to discuss how much previous studies might have overestimated the long term costs of CO 2 limitations and underestimated adjustment costs. It shows that, given a target date for atmospheric CO 2 concentration stabilisation, a higher inertia implies a lower optimal concentration trajectory. In a sequential decision framework, chapter 6 shows that current uncertainties about which CO 2 concentration ceiling would not present dangerous interference with the climate system justifies precautionary action. Finally, chapter 7 uses the irreversibility effect theory to define formally situations of decision under controversy and compare the irreversibility of CO 2 accumulation with the irreversibility of investments needed to moderate it. An option value for greenhouse gases emissions limitations is computed. (author)

  11. Irreversible performance of a quantum harmonic heat engine

    Science.gov (United States)

    Rezek, Yair; Kosloff, Ronnie

    2006-05-01

    The unavoidable irreversible loss of power in a heat engine is found to be of quantum origin. Following thermodynamic tradition, a model quantum heat engine operating in an Otto cycle is analysed, where the working medium is composed of an ensemble of harmonic oscillators and changes in volume correspond to changes in the curvature of the potential well. Equations of motion for quantum observables are derived for the complete cycle of operation. These observables are sufficient to determine the state of the system and with it all thermodynamical variables. Once the external controls are set, the engine settles to a limit cycle. Conditions for optimal work, power and entropy production are derived. At high temperatures and quasistatic operating conditions, the efficiency at maximum power coincides with the endoreversible result \\eta_q=1-\\sqrt{{T_c}/{T_h}} . The optimal compression ratio varies from {\\cal C} =\\sqrt{T_h/T_c} in the quasistatic limit where the irreversibility is dominated by heat conductance to {\\cal C} =(T_h/T_c)^{1/4} in the sudden limit when the irreversibility is dominated by friction. When the engine deviates from adiabatic conditions, the performance is subject to friction. The origin of this friction can be traced to the noncommutability of the kinetic and potential energy of the working medium.

  12. The effect of airflow rates and aeration mode on the respiration activity of four organic wastes: Implications on the composting process.

    Science.gov (United States)

    Mejias, Laura; Komilis, Dimitrios; Gea, Teresa; Sánchez, Antoni

    2017-07-01

    The aim of this study was to assess the effect of the airflow and of the aeration mode on the composting process of non-urban organic wastes that are found in large quantities worldwide, namely: (i) a fresh, non-digested, sewage sludge (FSS), (ii) an anaerobically digested sewage sludge (ADSS), (iii) cow manure (CM) and (iv) pig sludge (PS). This assessment was done using respirometric indices. Two aeration modes were tested, namely: (a) a constant air flowrate set at three different initial fixed airflow rates, and (b) an oxygen uptake rate (OUR)-controlled airflow rate. The four wastes displayed the same behaviour namely a limited biological activity at low aeration, while, beyond a threshold value, the increase of the airflow did not significantly increase the dynamic respiration indices (DRI 1 max , DRI 24 max and AT 4 ). The threshold airflow rate varied among wastes and ranged from 42NL air kg -1 DMh -1 for CM and from 67 to 77NL air kg -1 DMh -1 for FSS, ADSS and PS. Comparing the two aeration modes tested (constant air flow, OUR controlled air flow), no statistically significant differences were calculated between the respiration activity indices obtained at those two aeration modes. The results can be considered representative for urban and non-urban organic wastes and establish a general procedure to measure the respiration activity without limitations by airflow. This will permit other researchers to provide consistent results during the measurement of the respiration activity. Results indicate that high airflows are not required to establish the maximum respiration activity. This can result in energy savings and the prevention of off-gas treatment problems due to the excessive aeration rate in full scale composting plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Minimum airflow reset of single-duct VAV terminal boxes

    Science.gov (United States)

    Cho, Young-Hum

    Single duct Variable Air Volume (VAV) systems are currently the most widely used type of HVAC system in the United States. When installing such a system, it is critical to determine the minimum airflow set point of the terminal box, as an optimally selected set point will improve the level of thermal comfort and indoor air quality (IAQ) while at the same time lower overall energy costs. In principle, this minimum rate should be calculated according to the minimum ventilation requirement based on ASHRAE standard 62.1 and maximum heating load of the zone. Several factors must be carefully considered when calculating this minimum rate. Terminal boxes with conventional control sequences may result in occupant discomfort and energy waste. If the minimum rate of airflow is set too high, the AHUs will consume excess fan power, and the terminal boxes may cause significant simultaneous room heating and cooling. At the same time, a rate that is too low will result in poor air circulation and indoor air quality in the air-conditioned space. Currently, many scholars are investigating how to change the algorithm of the advanced VAV terminal box controller without retrofitting. Some of these controllers have been found to effectively improve thermal comfort, indoor air quality, and energy efficiency. However, minimum airflow set points have not yet been identified, nor has controller performance been verified in confirmed studies. In this study, control algorithms were developed that automatically identify and reset terminal box minimum airflow set points, thereby improving indoor air quality and thermal comfort levels, and reducing the overall rate of energy consumption. A theoretical analysis of the optimal minimum airflow and discharge air temperature was performed to identify the potential energy benefits of resetting the terminal box minimum airflow set points. Applicable control algorithms for calculating the ideal values for the minimum airflow reset were developed and

  14. Optimization at different loads by minimization of irreversibilities

    International Nuclear Information System (INIS)

    Wong, K.F.V.; Niu, Z.

    1991-01-01

    This paper reports that the irreversibility of the power cycle was chosen as the objective function as this function can successfully measure both the quality and quantity of energy flow in the cycle. Minimization of the irreversibility ensures that the power cycle will operate more efficiently. One feature of the present work is that the boiler, turbine, condenser and heaters are treated as one system for the purpose of optimization. In the optimization model, nine regression formulae are used, which are obtained from the measured test data. From the results of the present work, it can be seen that the optimization model developed can represent the effect of operational parameters on the power plant first and second law efficiency. Some of the results can be used to provide guidance for the optimal operation of the power plant. When the power cycle works at full load, the main steam temperature and pressure should be at the upper limit for minimal irreversibility of the system. If the load is less than 65% of its design capacity, the steam temperature and pressure should be decreased for a lower irreversibility of the system

  15. A Computational Study of the Respiratory Airflow Characteristics in Normal and Obstructed Human Airways

    Science.gov (United States)

    2014-01-01

    46] Y.S. Tzeng, K. Lutchen, M. Albert , The difference in ventilation heterogeneity between asthmatic and healthy subjects quantified using...endurance and diaphragmatic activation in patients with chronic airflow limitation, Thorax 44 (1989) 903–912. [52] V.K. Sidhaye, K.S. Schweitzer , M.J

  16. Strongly coupled interaction between a ridge of fluid and an inviscid airflow

    KAUST Repository

    Paterson, C.

    2015-07-01

    © 2015 AIP Publishing LLC. The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.

  17. Advanced airflow distribution methods for reduction of personal exposure to indoor pollutants

    DEFF Research Database (Denmark)

    Cao, Guangyu; Kosonen, Risto; Melikov, Arsen

    2016-01-01

    The main objective of this study is to recognize possible airflow distribution methods to protect the occupants from exposure to various indoor pollutants. The fact of the increasing exposure of occupants to various indoor pollutants shows that there is an urgent need to develop advanced airflow ...... distribution methods to reduce indoor exposure to various indoor pollutants. This article presents some of the latest development of advanced airflow distribution methods to reduce indoor exposure in various types of buildings.......The main objective of this study is to recognize possible airflow distribution methods to protect the occupants from exposure to various indoor pollutants. The fact of the increasing exposure of occupants to various indoor pollutants shows that there is an urgent need to develop advanced airflow...

  18. Irreversible climate change due to carbon dioxide emissions

    Science.gov (United States)

    Solomon, Susan; Plattner, Gian-Kasper; Knutti, Reto; Friedlingstein, Pierre

    2009-01-01

    The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6–1.9 m for peak CO2 concentrations exceeding ≈1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer. PMID:19179281

  19. Pulmonary function impairment in patients with combined pulmonary fibrosis and emphysema with and without airflow obstruction

    Directory of Open Access Journals (Sweden)

    Kitaguchi Y

    2014-07-01

    Full Text Available Yoshiaki Kitaguchi,1,2 Keisaku Fujimoto,3 Masayuki Hanaoka,1 Takayuki Honda,4 Junichi Hotta,2 Jiro Hirayama2 1First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, 2Department of Internal Medicine, Okaya City Hospital, Okaya, 3Department of Clinical Laboratory Sciences, 4Department of Laboratory Medicine, Shinshu University School of Medicine, Matsumoto, Japan Background: The syndrome of combined pulmonary fibrosis and emphysema (CPFE is a recently described entity associating upper-lobe emphysema and lower-lobe fibrosis. We sought to evaluate differences in pulmonary function between CPFE patients with and without airflow obstruction. Subjects and methods: Thirty-one CPFE patients were divided into two groups according to the presence or absence of irreversible airflow obstruction based on spirometry (forced expiratory volume in 1 second/forced vital capacity <70% following inhalation of a β2-agonist as follows: CPFE patients with airflow obstruction (CPFE OB+ group, n=11, and CPFE patients without airflow obstruction (CPFE OB– group, n=20. Pulmonary function, including respiratory impedance evaluated using impulse oscillometry and dynamic hyperinflation following metronome-paced incremental hyperventilation, was retrospectively analyzed in comparison with that observed in 49 chronic obstructive pulmonary disease (COPD patients (n=49. Results: In imaging findings, low-attenuation-area scores on chest high-resolution computed tomography, representing the degree of emphysema, were significantly lower in the CPFE OB– group than in the CPFE OB+ and COPD groups. In contrast, the severity of pulmonary fibrosis was greater in the CPFE OB– group than in the CPFE OB+ group. In pulmonary function, lung hyperinflation was not apparent in the CPFE OB– group. Impairment of diffusion capacity was severe in both the CPFE OB– and CPFE OB+ groups. Impulse oscillometry showed that respiratory resistance was not

  20. Real-time visualization and analysis of airflow field by use of digital holography

    Science.gov (United States)

    Di, Jianglei; Wu, Bingjing; Chen, Xin; Liu, Junjiang; Wang, Jun; Zhao, Jianlin

    2013-04-01

    The measurement and analysis of airflow field is very important in fluid dynamics. For airflow, smoke particles can be added to visually observe the turbulence phenomena by particle tracking technology, but the effect of smoke particles to follow the high speed airflow will reduce the measurement accuracy. In recent years, with the advantage of non-contact, nondestructive, fast and full-field measurement, digital holography has been widely applied in many fields, such as deformation and vibration analysis, particle characterization, refractive index measurement, and so on. In this paper, we present a method to measure the airflow field by use of digital holography. A small wind tunnel model made of acrylic glass is built to control the velocity and direction of airflow. Different shapes of samples such as aircraft wing and cylinder are placed in the wind tunnel model to produce different forms of flow field. With a Mach-Zehnder interferometer setup, a series of digital holograms carrying the information of airflow filed distributions in different states are recorded by CCD camera and corresponding holographic images are numerically reconstructed from the holograms by computer. Then we can conveniently obtain the velocity or pressure information of the airflow deduced from the quantitative phase information of holographic images and visually display the airflow filed and its evolution in the form of a movie. The theory and experiment results show that digital holography is a robust and feasible approach for real-time visualization and analysis of airflow field.

  1. Integration of a Multizone Airflow Model into a Thermalsimulation Program

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Sørensen, Karl Grau; Heiselberg, Per

    2007-01-01

    An existing computer model for dynamic hygrothermal analysis of buildings has been extended with a multizone airflow model based on loop equations to account for the coupled thermal and airflow in natural and hybrid ventilated buildings. In water distribution network and related fields loop...... a methodology adopted from water distribution network that automatically sets up the independent loops and is easy to implement into a computer program. Finally an example of verification of the model is given which demonstrates the ability of the models to accurately predict the airflow of a simple multizone...

  2. Air-flow resistances of silicone rubber voice prostheses after formation of bacterial and fungal biofilms

    NARCIS (Netherlands)

    Elving, GJ; van der Mei, HC; Busscher, HJ; van Weissenbruch, R; Albers, FWJ

    Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses by causing leakage or an increased air-flow resistance and the prosthesis has to be replaced. To determine which bacterial or yeast strains,

  3. Behavior of HEPA filters under high humidity airflows

    International Nuclear Information System (INIS)

    Ricketts, C.I.

    1992-10-01

    To help determine and improve the safety margins of High Efficiency Particulate Air (HEPA) filter units in nuclear facilities under possible accident conditions, the structural limits and failure mechanisms of filter in high-humidity airflows were established and the fundamental physical phenomena underlying filter failure or malfunction in humid air were identified. Empirical models for increases in filter pressure drop with time in terms of the relevant airstream parameters were also developed. The weaknesses of currently employed humidity countermeasures used in filter protection are discussed and fundamental explanations for reported filter failures in normal service are given. (orig./DG) [de

  4. Current situation of asthma-COPD overlap syndrome (ACOS) in Chinese patients older than 40 years with airflow limitation: rationale and design for a multicenter, cross-sectional trial (study protocol).

    Science.gov (United States)

    Kang, Jian; Yao, Wanzhen; Cai, Baiqiang; Chen, Ping; Ling, Xia; Shang, Hongyan

    2016-12-01

    Asthma and chronic obstructive pulmonary disease (COPD) are the frequently occurring chronic airway diseases, and the overlapping syndrome observed in the majority of patients has been recently defined as asthma-COPD overlap syndrome (ACOS) by the Global Initiative for Chronic Obstructive Lung (GOLD, 2014) and Global initiative for Asthma (GINA, 2015). The proportion, features, and clinical practice of ACOS still remain elusive in China. We are conducting this multicenter, cross-sectional, observational study (NCT02600221) to investigate the distributions of chronic obstructive diseases in patients >40 years of age with chronic airflow limitation in China along with determination of the main clinical practice and features of these diseases. The study will also explore the factors that may influence the exacerbations and severity of ACOS in Chinese patients (>40 years of age). A total of 2,000 patients (age, ≥40 years; either sex) who are clinically diagnosed as having asthma, COPD/chronic bronchitis/emphysema, or ACOS for at least 12 months with airflow limitation [post-bronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV 1 /FVC): current situation, main clinical practice, and features of ACOS, asthma, and COPD conditions in Chinese patients. The insights will be helpful in designing optimal management strategies for ACOS and redefining the healthcare development programs.

  5. Unidirectional pulmonary airflow patterns in the savannah monitor lizard.

    Science.gov (United States)

    Schachner, Emma R; Cieri, Robert L; Butler, James P; Farmer, C G

    2014-02-20

    The unidirectional airflow patterns in the lungs of birds have long been considered a unique and specialized trait associated with the oxygen demands of flying, their endothermic metabolism and unusual pulmonary architecture. However, the discovery of similar flow patterns in the lungs of crocodilians indicates that this character is probably ancestral for all archosaurs--the group that includes extant birds and crocodilians as well as their extinct relatives, such as pterosaurs and dinosaurs. Unidirectional flow in birds results from aerodynamic valves, rather than from sphincters or other physical mechanisms, and similar aerodynamic valves seem to be present in crocodilians. The anatomical and developmental similarities in the primary and secondary bronchi of birds and crocodilians suggest that these structures and airflow patterns may be homologous. The origin of this pattern is at least as old as the split between crocodilians and birds, which occurred in the Triassic period. Alternatively, this pattern of flow may be even older; this hypothesis can be tested by investigating patterns of airflow in members of the outgroup to birds and crocodilians, the Lepidosauromorpha (tuatara, lizards and snakes). Here we demonstrate region-specific unidirectional airflow in the lungs of the savannah monitor lizard (Varanus exanthematicus). The presence of unidirectional flow in the lungs of V. exanthematicus thus gives rise to two possible evolutionary scenarios: either unidirectional airflow evolved independently in archosaurs and monitor lizards, or these flow patterns are homologous in archosaurs and V. exanthematicus, having evolved only once in ancestral diapsids (the clade encompassing snakes, lizards, crocodilians and birds). If unidirectional airflow is plesiomorphic for Diapsida, this respiratory character can be reconstructed for extinct diapsids, and evolved in a small ectothermic tetrapod during the Palaeozoic era at least a hundred million years before the

  6. Lung sound intensity in patients with emphysema and in normal subjects at standardised airflows

    NARCIS (Netherlands)

    Schreur, H. J.; Sterk, P. J.; Vanderschoot, J.; van Klink, H. C.; van Vollenhoven, E.; Dijkman, J. H.

    1992-01-01

    A common auscultatory finding in pulmonary emphysema is a reduction of lung sounds. This might be due to a reduction in the generation of sounds due to the accompanying airflow limitation or to poor transmission of sounds due to destruction of parenchyma. Lung sound intensity was investigated in

  7. Airflow Measurement of the Car HVAC Unit Using Hot-wire Anemometry

    Directory of Open Access Journals (Sweden)

    Fojtlín Miloš

    2016-01-01

    Full Text Available Thermal environment in a vehicular cabin significantly influence drivers’ fatigue and passengers’ thermal comfort. This environment is traditionally managed by HVAC cabin system that distributes air and modifies its properties. In order to simulate cabin thermal behaviour, amount of the air led through car vents must be determined. The aim of this study was to develop methodology to measure airflow from the vents, and consequently calculate corresponding air distribution coefficients. Three climatic cases were selected to match European winter, summer, and spring / fall conditions. Experiments were conducted on a test vehicle in a climatic chamber. The car HVAC system was set to automatic control mode, and the measurements were executed after the system stabilisation—each case was independently measured three times. To be able to evaluate precision of the method, the airflow was determined at the system inlet (HVAC suction and outlet (each vent, and the total airflow values were compared. The airflow was calculated by determining a mean value of the air velocity multiplied by an area of inlet / outlet cross-section. Hot-wire anemometry was involved to measure the air velocity. Regarding the summer case, total airflow entering the cabin was around 57 l s-1 with 60 % of the air entering the cabin through dashboard vents; no air was supplied to the feet compartment. The remaining cases had the same total airflow of around 42 l s-1, and the air distribution was focused mainly on feet and windows. The inlet and outlet airflow values show a good match with a maximum mass differential of 8.3 %.

  8. Irreversible processes kinetic theory

    CERN Document Server

    Brush, Stephen G

    2013-01-01

    Kinetic Theory, Volume 2: Irreversible Processes deals with the kinetic theory of gases and the irreversible processes they undergo. It includes the two papers by James Clerk Maxwell and Ludwig Boltzmann in which the basic equations for transport processes in gases are formulated, together with the first derivation of Boltzmann's ""H-theorem"" and a discussion of this theorem, along with the problem of irreversibility.Comprised of 10 chapters, this volume begins with an introduction to the fundamental nature of heat and of gases, along with Boltzmann's work on the kinetic theory of gases and s

  9. Study on remote control technology of airflow during a mine fire

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.; Wang, Y; Zhou, Y.; Zhou, F. [China University of Mining and Technology, Jiangsu (China). College of Mineral and Energy Resource

    2001-07-01

    In order to realize remote control of airflow during a mine fire and minimize fire losses, two kinds of the airflow remote control systems have been developed. One uses compressed air as power source, and transmits control signals by a monitor system for mine environment. Another uses electric power and transmits control signals through a telephone network underground. The mine door controllers of the remote airflow controlling systems are developed with a single-chip microcomputer. Then the controller can not only do logical analysis and judgement, but also has a strong anti-disturb ability and sufficient reliability. The two kinds of airflow remote control system have been successfully applied in some coal mines in China. Their effects of running are very good. 2 refs., 5 figs.

  10. Estimation of Airflow in Livestock Buildings using Image Analysis

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1996-01-01

    of a livestock building, the airflow in a laser-illuminated plane may be visualized. Based on sequences of images recorded of this plane using a video camera, estimates of 2--D flow vectors are derived locally. The local estimates of velocity are found using a set of spatio-temporal convolution filters...... and camera may be placed so they do not disturb the airflow) for estimating air velocity in a 2--D plane.......In order to evaluate a given ventilation system in a livestock building and its sensitivity to wind, presence of heat sources (e.g. livestock) etc. it is of interest to estimate flow vector fields corresponding to the airflow. By introducing particles (e.g. smoke) into the air inlets of a model...

  11. Investigation of airflow effects on the dielectric barrier discharge with single/double discharge channel arrangement

    Science.gov (United States)

    Fan, Zhihui; Yan, Huijie; Liu, Yidi; Guo, Hongfei; Wang, Yuying; Ren, Chunsheng

    2018-05-01

    Atmospheric-pressure dielectric barrier discharge (DBD) with airflow participation has been widely used in recent years. In this paper, effects of airflow on DBD characteristics are experimentally investigated by single/double pin-to-plate DBD arrangements with an AC exciting source. The discharge electrical characteristics and the movements of discharge channels in airflow are investigated with a single pin electrode arrangement. The current intensities increase in positive cycles and decrease in negative cycles with the increase in airflow velocity. The transition from a filamentary discharge to a diffuse discharge is observed under certain airflow conditions, and the discharge channels move with the airflow with a movement velocity less than the corresponding airflow velocity. In the cases of double pin electrode arrangements, the repulsion between double pin discharge channels is apparent at a 10 mm distance but is not obvious at a 20 mm distance. When the airflow is introduced into the discharge gap, not as in the case of single pin electrode arrangement, the movements of discharge channels in airflow are affected by adjacent discharge channels. The corresponding reasons are analyzed in the paper.

  12. Finite Element Modeling of Airflow During Phonation

    Directory of Open Access Journals (Sweden)

    Šidlof P.

    2010-07-01

    Full Text Available In the paper a mathematical model of airflow in human vocal folds is presented. The geometry of the glottal channel is based on measurements of excised human larynges. The airflow is modeled by nonstationary incompressible Navier-Stokes equations in a 2D computational domain, which is deformed in time due to vocal fold vibration. The paper presents numerical results and focuses on flow separation in glottis. Quantitative data from numerical simulations are compared to results of measurements by Particle Image Velocimetry (PIV, performed on a scaled self-oscillating physical model of vocal folds.

  13. Inflammatory Biomarkers Predict Airflow Obstruction After Exposure to World Trade Center Dust

    Science.gov (United States)

    Nolan, Anna; Naveed, Bushra; Comfort, Ashley L.; Ferrier, Natalia; Hall, Charles B.; Kwon, Sophia; Kasturiarachchi, Kusali J.; Cohen, Hillel W.; Zeig-Owens, Rachel; Glaser, Michelle S.; Webber, Mayris P.; Aldrich, Thomas K.; Rom, William N.; Kelly, Kerry; Prezant, David J.

    2012-01-01

    Background: The World Trade Center (WTC) collapse on September 11, 2001, produced airflow obstruction in a majority of firefighters receiving subspecialty pulmonary evaluation (SPE) within 6.5 years post-September 11, 2001. Methods: In a cohort of 801 never smokers with normal pre-September 11, 2001, FEV1, we correlated inflammatory biomarkers and CBC counts at monitoring entry within 6 months of September 11, 2001, with a median FEV1 at SPE (34 months; interquartile range, 25-57). Cases of airflow obstruction had FEV1 less than the lower limit of normal (LLN) (100 of 801; 70 of 100 had serum), whereas control subjects had FEV1 greater than or equal to LLN (153 of 801; 124 of 153 had serum). Results: From monitoring entry to SPE years later, FEV1 declined 12% in cases and increased 3% in control subjects. Case subjects had elevated serum macrophage derived chemokine (MDC), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor, and interferon inducible protein-10 levels. Elevated GM-CSF and MDC increased the risk for subsequent FEV1 less than LLN by 2.5-fold (95% CI, 1.2-5.3) and 3.0-fold (95% CI, 1.4-6.1) in a logistic model adjusted for exposure, BMI, age on September 11, 2001, and polymorphonuclear neutrophils. The model had sensitivity of 38% (95% CI, 27-51) and specificity of 88% (95% CI, 80-93). Conclusions: Inflammatory biomarkers can be risk factors for airflow obstruction following dust and smoke exposure. Elevated serum GM-CSF and MDC levels soon after WTC exposure were associated with increased risk of airflow obstruction in subsequent years. Biomarkers of inflammation may help identify pathways producing obstruction after irritant exposure. PMID:21998260

  14. Airflow-Restricting Mask Reduces Acute Performance in Resistance Exercise

    Directory of Open Access Journals (Sweden)

    Yuri L. Motoyama

    2016-09-01

    Full Text Available Background: The aim of this study was to compare the number of repetitions to volitional failure, the blood lactate concentration, and the perceived exertion to resistance training with and without an airflow-restricting mask. Methods: Eight participants participated in a randomized, counterbalanced, crossover study. Participants were assigned to an airflow-restricting mask group (MASK or a control group (CONT and completed five sets of chest presses and parallel squats until failure at 75% one-repetition-maximum test (1RM with 60 s of rest between sets. Ratings of perceived exertion (RPEs, blood lactate concentrations (Lac−, and total repetitions were taken after the training session. Results: MASK total repetitions were lower than those of the CONT, and (Lac− and MASK RPEs were higher than those of the CONT in both exercises. Conclusions: We conclude that an airflow-restricting mask in combination with resistance training increase perceptions of exertion and decrease muscular performance and lactate concentrations when compared to resistance training without this accessory. This evidence shows that the airflow-restricting mask may change the central nervous system and stop the exercise beforehand to prevent some biological damage.

  15. Function and phenotype of peripheral neutrophils in the characterization of COPD patients

    NARCIS (Netherlands)

    Langereis, J.D.

    2010-01-01

    COPD is a major health problem worldwide and is currently the third cause of morbidity and mortality in the European Union. COPD is a heterogeneous disease that is characterized by irreversible airflow limitation and parenchymal destruction. The severity of COPD is categorized in 5 stages as

  16. Inhaled indacaterol for the treatment of COPD patients with destroyed lung by tuberculosis and moderate-to-severe airflow limitation: results from the randomized INFINITY study.

    Science.gov (United States)

    Kim, Cheong-Ju; Yoon, Hyoung-Kyu; Park, Myung-Jae; Yoo, Kwang-Ha; Jung, Ki-Suck; Park, Jeong-Woong; Lim, Seong Yong; Shim, Jae Jeong; Lee, Yong Chul; Kim, Young-Sam; Oh, Yeon-Mok; Kim, Song; Yoo, Chul-Gyu

    2017-01-01

    Pulmonary tuberculosis (TB) is a risk factor for chronic obstructive pulmonary disease (COPD); however, few clinical studies have investigated treatment effectiveness in COPD patients with destroyed lung by TB. The Indacaterol effectiveness in COPD patients with Tuberculosis history (INFINITY) study assessed the efficacy and safety of once-daily inhaled indacaterol 150 µg for the treatment of Korean COPD patients with destroyed lung by TB and moderate-to-severe airflow limitation. This was a multicenter, double-blind, parallel-group study, in which eligible patients were randomized (1:1) to receive either once-daily indacaterol 150 µg or placebo for 8 weeks. The primary efficacy endpoint was change from baseline in trough forced expiratory volume in 1 s at Week 8; the secondary endpoints included changes in transition dyspnea index score and St George's Respiratory Questionnaire for COPD score at Week 8. Safety was evaluated over 8 weeks. Of the 136 patients randomized, 119 (87.5%) completed the study treatment. At Week 8, indacaterol significantly improved trough forced expiratory volume in 1 s versus placebo (treatment difference [TD] 140 mL, P <0.001). Statistically significant improvement in transition dyspnea index score (TD =0.78, P <0.05) and numerical improvement in St George's Respiratory Questionnaire for COPD score (TD =-2.36, P =0.3563) were observed with indacaterol versus placebo at Week 8. Incidence of adverse events was comparable between the treatment groups. Indacaterol provided significantly superior bronchodilation, significant improvement in breathlessness and improved health status with comparable safety versus placebo in Korean COPD patients with destroyed lung by TB and moderate-to-severe airflow limitation.

  17. Airflow and radon transport modeling in four large buildings

    International Nuclear Information System (INIS)

    Fan, J.B.; Persily, A.K.

    1995-01-01

    Computer simulations of multizone airflow and contaminant transport were performed in four large buildings using the program CONTAM88. This paper describes the physical characteristics of the buildings and their idealizations as multizone building airflow systems. These buildings include a twelve-story multifamily residential building, a five-story mechanically ventilated office building with an atrium, a seven-story mechanically ventilated office building with an underground parking garage, and a one-story school building. The air change rates and interzonal airflows of these buildings are predicted for a range of wind speeds, indoor-outdoor temperature differences, and percentages of outdoor air intake in the supply air Simulations of radon transport were also performed in the buildings to investigate the effects of indoor-outdoor temperature difference and wind speed on indoor radon concentrations

  18. Interleukin-6 and airflow limitation in chemical warfare patients with chronic obstructive pulmonary disease

    Science.gov (United States)

    Attaran, Davood; Lari, Shahrzad M; Towhidi, Mohammad; Marallu, Hassan Ghobadi; Ayatollahi, Hossein; Khajehdaluee, Mohammad; Ghanei, Mostafa; Basiri, Reza

    2010-01-01

    Objectives Chronic obstructive pulmonary disease (COPD) is one of the main late complications of sulfur mustard poisoning. The aim of this study was to evaluate serum levels of interleukin (IL)-6 in war veterans with pulmonary complications of sulfur mustard poisoning and their correlation with severity of airways disease. Methods Fifty consecutive patients with sulfur mustard poisoning and stable COPD, and of mean age 46.3 ± 9.18 years were enrolled in this study. Thirty healthy men were selected as controls and matched to cases by age and body mass index. Spirometry, arterial blood gas, six- minute walk test, BODE (body mass index, obstruction, dyspnea, and exercise capacity), and St George’s Respiratory Questionnaire about quality of life were evaluated. Serum IL-6 was measured in both patient and control groups. Results Fifty-four percent of patients had moderate COPD. Mean serum IL-6 levels were 15.01 ± standard deviation (SD) 0.61 pg/dL and 4.59 ± 3.40 pg/dL in the case and control groups, respectively (P = 0.03). There was a significant correlation between IL-6 levels and Global Initiative for Chronic Obstructive Lung Disease stage (r = 0.25, P = 0.04) and between IL-6 and BODE index (r = 0.38, P = 0.01). There was also a significant negative correlation between serum IL-6 and forced expiratory volume in one second (FEV1, r = −0.36, P = 0.016). Conclusion Our findings suggest that serum IL-6 is increased in patients with sulfur mustard poisoning and COPD, and may have a direct association with airflow limitation. PMID:21037957

  19. Computer simulation of airflow through a multi-generation tracheobronchial conducting airway

    Energy Technology Data Exchange (ETDEWEB)

    Fan, B.; Cheng, Yung-Sung; Yeh, Hsu-Chi

    1995-12-01

    Knowledge of airflow patterns in the human lung is important for an analysis of lung diseases and drug delivery of aerosolized medicine for medical treatment. However, very little systematic information is available on the pattern of airflow in the lung and on how this pattern affects the deposition of toxicants in the lung, and the efficacy of aerosol drug therapy. Most previous studies have only considered the airflow through a single bifurcating airway. However, the flow in a network of more than one bifurcation is more complicated due to the effect of interrelated lung generations. Because of the variation of airway geometry and flow condition from generation to generation, a single bifurcating airway cannot be taken as a representative for the others in different generations. The flow in the network varies significantly with airway generations because of a redistribution of axial momentum by the secondary flow motions. The influence of the redistribution of flow is expected in every generation. Therefore, a systematic information of the airflow through a multi-generation tracheobronchial conducting airway is needed, and it becomes the purpose of this study. This study has provided information on airflow in a lung model which is necessary to the study of the deposition of toxicants and therapeutic aerosols.

  20. Computer simulation of airflow through a multi-generation tracheobronchial conducting airway

    International Nuclear Information System (INIS)

    Fan, B.; Cheng, Yung-Sung; Yeh, Hsu-Chi.

    1995-01-01

    Knowledge of airflow patterns in the human lung is important for an analysis of lung diseases and drug delivery of aerosolized medicine for medical treatment. However, very little systematic information is available on the pattern of airflow in the lung and on how this pattern affects the deposition of toxicants in the lung, and the efficacy of aerosol drug therapy. Most previous studies have only considered the airflow through a single bifurcating airway. However, the flow in a network of more than one bifurcation is more complicated due to the effect of interrelated lung generations. Because of the variation of airway geometry and flow condition from generation to generation, a single bifurcating airway cannot be taken as a representative for the others in different generations. The flow in the network varies significantly with airway generations because of a redistribution of axial momentum by the secondary flow motions. The influence of the redistribution of flow is expected in every generation. Therefore, a systematic information of the airflow through a multi-generation tracheobronchial conducting airway is needed, and it becomes the purpose of this study. This study has provided information on airflow in a lung model which is necessary to the study of the deposition of toxicants and therapeutic aerosols

  1. Experimental study on the characterization of airflow effect on the direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kuan, Yean-Der [Department of Refrigeration, Air Conditioning and Energy Engineering, National Chin-Yi University of Technology, Taichung (China); Lee, Shi-Min [Department of Aerospace Engineering, Tamkang University, Taipei (China); Sung, Min-Feng [Department of Mechanical and Electromechanical Engineering, Tamkang University, Taipei (China)

    2009-08-15

    The PCB manufacturing process has been applied to the DMFC package which is especially suitable for the planar type DMFC module design. Maintaining the planar DMFC in good operating condition is an important task. This paper discusses the cathode airflow effect on the single cell and also on the 3-cell planar DMFC module. In the single cell study, the research starts from the airflow rate to airflow velocity viewpoint. In the DMFC module study, a 3-cell DMFC module, a substitute of 3-Cell PCB DMFC module, with a parallel flow board are compared. The results indicate that providing suitable cathode airflow velocity is more important than merely considering the airflow rate in the DMFC single or 3-cell DMFC module. (author)

  2. Irreversibility and self-organization in spin glasses. 1. Origin of irreversibility in spin glasses

    International Nuclear Information System (INIS)

    Kovrov, V.P.; Kurbatov, A.M.

    1989-05-01

    The origin of irreversibility in spin glasses is found out on the basis of the analytical study of the well-known TAP equations. Connection between irreversible jumpwise transitions and a positive feedback in spin glasses is discussed. (author). 7 refs, 4 figs

  3. Influence of furnishing on indoor airflow near external walls

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Rode, Carsten; Peuhkuri, Ruut

    2008-01-01

    Simulations of indoor environments in buildings are usually performed assuming uniform distribution of temperature and humidity of the indoor air, such as it would be in an idealised unfurnished room. The flow patterns near external walls may however be very different from the undisturbed airflow...... distributions, as the walls behind furniture may be colder than the other surroundings of the room, and the furniture to some extent obstructs the airflow. This paper describes an investigation of a room with a piece of furniture placed near an external wall. This was investigated using Particle Image...... Velocimetry (PIV) measurements. It was found how the pattern of airflow behind furniture placed near cold walls was influenced by the thickness of air gaps behind and below the furniture. But it was also found that even if the furniture was placed directly on the floor, there would be a considerable flow...

  4. Experimental Research on Optimizing Inlet Airflow of Wet Cooling Towers under Crosswind Conditions

    Science.gov (United States)

    Chen, You Liang; Shi, Yong Feng; Hao, Jian Gang; Chang, Hao; Sun, Feng Zhong

    2018-01-01

    A new approach of installing air deflectors around tower inlet circumferentially was proposed to optimize the inlet airflow and reduce the adverse effect of crosswinds on the thermal performance of natural draft wet cooling towers (NDWCT). And inlet airflow uniformity coefficient was defined to analyze the uniformity of circumferential inlet airflow quantitatively. Then the effect of air deflectors on the NDWCT performance was investigated experimentally. By contrast between inlet air flow rate and cooling efficiency, it has been found that crosswinds not only decrease the inlet air flow rate, but also reduce the uniformity of inlet airflow, which reduce NDWCT performance jointly. After installing air deflectors, the inlet air flow rate and uniformity coefficient increase, the uniformity of heat and mass transfer increases correspondingly, which improve the cooling performance. In addition, analysis on Lewis factor demonstrates that the inlet airflow optimization has more enhancement of heat transfer than mass transfer, but leads to more water evaporation loss.

  5. Measurement of the resistivity of porous materials with an alternating air-flow method.

    Science.gov (United States)

    Dragonetti, Raffaele; Ianniello, Carmine; Romano, Rosario A

    2011-02-01

    Air-flow resistivity is a main parameter governing the acoustic behavior of porous materials for sound absorption. The international standard ISO 9053 specifies two different methods to measure the air-flow resistivity, namely a steady-state air-flow method and an alternating air-flow method. The latter is realized by the measurement of the sound pressure at 2 Hz in a small rigid volume closed partially by the test sample. This cavity is excited with a known volume-velocity sound source implemented often with a motor-driven piston oscillating with prescribed area and displacement magnitude. Measurements at 2 Hz require special instrumentation and care. The authors suggest an alternating air-flow method based on the ratio of sound pressures measured at frequencies higher than 2 Hz inside two cavities coupled through a conventional loudspeaker. The basic method showed that the imaginary part of the sound pressure ratio is useful for the evaluation of the air-flow resistance. Criteria are discussed about the choice of a frequency range suitable to perform simplified calculations with respect to the basic method. These criteria depend on the sample thickness, its nonacoustic parameters, and the measurement apparatus as well. The proposed measurement method was tested successfully with various types of acoustic materials.

  6. Examination of various postulates of irreversibility

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, J [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)

    1977-01-01

    Firstly, it is shown that it is necessary to break the reversible character of the B.B.G.K.Y. system of equations by means of a postulate of irreversibility to obtain a kinetic equation compatible with the second principle of thermodynamics. Next, three postulates of irreversibility are examined: that of molecular chaos, that of linear relaxation and, finally, that of superposition. Then the corresponding kinetic equations and the expressions for the viscosity coefficient to which they lead are determined. Comparison with experiment is made each time. Lastly, an attempt to obtain an irreversible kinetic equation without introducing a postulate of irreversibility in the B.B.G.K.Y. system is realized. This consists in adding a complementary irreversible term to the fundamental equation of the dynamics of a particle. The suggested term is of quantum origin and leads to a kinetic equation of the Fokker-Planck type.

  7. Irreversible denaturation of maltodextrin glucosidase studied by differential scanning calorimetry, circular dichroism, and turbidity measurements.

    Science.gov (United States)

    Goyal, Megha; Chaudhuri, Tapan K; Kuwajima, Kunihiro

    2014-01-01

    Thermal denaturation of Escherichia coli maltodextrin glucosidase was studied by differential scanning calorimetry, circular dichroism (230 nm), and UV-absorption measurements (340 nm), which were respectively used to monitor heat absorption, conformational unfolding, and the production of solution turbidity. The denaturation was irreversible, and the thermal transition recorded at scan rates of 0.5-1.5 K/min was significantly scan-rate dependent, indicating that the thermal denaturation was kinetically controlled. The absence of a protein-concentration effect on the thermal transition indicated that the denaturation was rate-limited by a mono-molecular process. From the analysis of the calorimetric thermograms, a one-step irreversible model well represented the thermal denaturation of the protein. The calorimetrically observed thermal transitions showed excellent coincidence with the turbidity transitions monitored by UV-absorption as well as with the unfolding transitions monitored by circular dichroism. The thermal denaturation of the protein was thus rate-limited by conformational unfolding, which was followed by a rapid irreversible formation of aggregates that produced the solution turbidity. It is thus important to note that the absence of the protein-concentration effect on the irreversible thermal denaturation does not necessarily means the absence of protein aggregation itself. The turbidity measurements together with differential scanning calorimetry in the irreversible thermal denaturation of the protein provided a very effective approach for understanding the mechanisms of the irreversible denaturation. The Arrhenius-equation parameters obtained from analysis of the thermal denaturation were compared with those of other proteins that have been reported to show the one-step irreversible thermal denaturation. Maltodextrin glucosidase had sufficiently high kinetic stability with a half-life of 68 days at a physiological temperature (37°C).

  8. Strongly coupled interaction between a ridge of fluid and an inviscid airflow

    KAUST Repository

    Paterson, C.; Wilson, S. K.; Duffy, B. R.

    2015-01-01

    ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength

  9. Ecological optimization for generalized irreversible Carnot refrigerators

    International Nuclear Information System (INIS)

    Chen Lingen; Zhu Xiaoqin; Sun Fengrui; Wu Chih

    2005-01-01

    The optimal ecological performance of a Newton's law generalized irreversible Carnot refrigerator with the losses of heat resistance, heat leakage and internal irreversibility is derived by taking an ecological optimization criterion as the objective, which consists of maximizing a function representing the best compromise between the exergy output rate and exergy loss rate (entropy production rate) of the refrigerator. Numerical examples are given to show the effects of heat leakage and internal irreversibility on the optimal performance of generalized irreversible refrigerators

  10. Using Computational Fluid Dynamics to examine airflow characteristics in Empty Nose Syndrome

    Science.gov (United States)

    Flint, Tim; Esmaily-Moghadam, Mahdi; Thamboo, Andrew; Velasquez, Nathalia; Nayak, Jayakar V.; Sellier, Mathieu; Moin, Parviz

    2016-11-01

    The enigmatic disorder, empty nose syndrome (ENS), presents with a complex subjective symptom profile despite objectively patent nasal airways, and recent reports suggest that surgical augmentation of the nasal airway can improve quality of life and ENS-related complaints. In this study, computational fluid dynamics (CFD) was performed both prior to, and following, inferior turbinate augmentation to model the resultant changes in airflow patterns and better understand the pathophysiology of ENS. An ENS patient with marked reduction in ENS symptoms following turbinate augmentation was identified, and pre- and post-operative CT imaging was collected. A Finite element framework with the variational multiscale method (Esmaily-Moghadam, Comput. Methods Appl. Mech. Engrg. 2015) was used to compute the airflow, temperature, and moisture transport through the nasal cavity. Comparison of the CFD results following corrective surgery showed higher levels of airflow turbulence. Augmentation produced 50%, 25%, and 25% increases in root mean square pressure, wall shear stress, and heat flux respectively. These results provide insight into the changes in nasal airflow characteristics attainable through surgical augmentation, and by extension, how nasal airflow patterns may be distorted in the 'overly patent' airway of ENS patients. Supported by Stanford University CTR and Fulbright New Zealand.

  11. Fault tolerant attitude control for small unmanned aircraft systems equipped with an airflow sensor array.

    Science.gov (United States)

    Shen, H; Xu, Y; Dickinson, B T

    2014-11-18

    Inspired by sensing strategies observed in birds and bats, a new attitude control concept of directly using real-time pressure and shear stresses has recently been studied. It was shown that with an array of onboard airflow sensors, small unmanned aircraft systems can promptly respond to airflow changes and improve flight performances. In this paper, a mapping function is proposed to compute aerodynamic moments from the real-time pressure and shear data in a practical and computationally tractable formulation. Since many microscale airflow sensors are embedded on the small unmanned aircraft system surface, it is highly possible that certain sensors may fail. Here, an adaptive control system is developed that is robust to sensor failure as well as other numerical mismatches in calculating real-time aerodynamic moments. The advantages of the proposed method are shown in the following simulation cases: (i) feedback pressure and wall shear data from a distributed array of 45 airflow sensors; (ii) 50% failure of the symmetrically distributed airflow sensor array; and (iii) failure of all the airflow sensors on one wing. It is shown that even if 50% of the airflow sensors have failures, the aircraft is still stable and able to track the attitude commands.

  12. Ecological optimization of an irreversible quantum Carnot heat engine with spin-1/2 systems

    International Nuclear Information System (INIS)

    Liu Xiaowei; Chen Lingen; Wu Feng; Sun Fengrui

    2010-01-01

    A model of a quantum heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting spin-1/2 systems is established in this paper. The quantum heat engine cycle is composed of two isothermal processes and two irreversible adiabatic processes and is referred to as a spin quantum Carnot heat engine. Based on the quantum master equation and the semi-group approach, equations of some important performance parameters, such as power output, efficiency, entropy generation rate and ecological function (a criterion representing the optimal compromise between exergy output rate and exergy loss rate), for the irreversible spin quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. The effects of internal irreversibility and heat leakage on ecological performance are discussed in detail.

  13. Characterization of the Airflow from a Bottom Hung Window under Natural Ventilation

    DEFF Research Database (Denmark)

    Svidt, Kjeld; Heiselberg, Per; Nielsen, Peter V.

    This paper describes the results of laboratory measurements of the airflow from a bottom hung window mounted near the ceiling of a ventilated room. In the laboratory set-up it was possible to control the temperature difference and the airflow rate through the window. The pressure drop through...

  14. The efficacy of airflow and seat vibration on reducing visually induced motion sickness.

    Science.gov (United States)

    D'Amour, Sarah; Bos, Jelte E; Keshavarz, Behrang

    2017-09-01

    Visually induced motion sickness (VIMS) is a well-known sensation in virtual environments and simulators, typically characterized by a variety of symptoms such as pallor, sweating, dizziness, fatigue, and/or nausea. Numerous methods to reduce VIMS have been previously introduced; however, a reliable countermeasure is still missing. In the present study, the effect of airflow and seat vibration to alleviate VIMS was investigated. Eighty-two participants were randomly assigned to one of four groups (airflow, vibration, combined airflow and vibration, and control) and then exposed to a 15 min long video of a bicycle ride shot from first-person view. VIMS was measured using the Fast Motion Sickness Scale (FMS) and the Simulator Sickness Questionnaire (SSQ). Results showed that the exposure of airflow significantly reduced VIMS, whereas the presence of seat vibration, in contrast, did not have an impact on VIMS. Additionally, we found that females reported higher FMS scores than males, however, this sex difference was not found in the SSQ scores. Our findings demonstrate that airflow can be an effective and easy-to-apply technique to reduce VIMS in virtual environments and simulators, while vibration applied to the seat is not a successful method.

  15. Prevalence of airflow obstruction in patients with stable systolic heart failure

    DEFF Research Database (Denmark)

    Dalsgaard, Morten; Plesner, Louis Lind; Schou, Morten

    2017-01-01

    Background: Chronic obstructive pulmonary disease (COPD) is an important differential diagnosis in heart failure (HF). However, routine use of spirometry in outpatient HF clinics is not implemented. The aim of the present study was to determine the prevalence of both airflow obstruction and non...... failure clinics were examined with spirometry at their first visit and after optimal medical treatment for HF was achieved. airflow obstruction was classified and graded according to the GOLD 2011 revision. Results: Baseline spirometry was performed in 593 included patients and 71 (12%) had a clinical......%) had mild disease (GOLD I) and 180 (30%) patients had moderate to very severe disease (GOLD II-IV). No difference in spirometric variables was observed following up titration of medication. Conclusion: In stable patients with HF airflow obstruction is frequent and severely underdiagnosed. Spirometry...

  16. Harvesting energy from airflow with a michromachined piezoelectric harvester inside a Helmholtz resonator

    NARCIS (Netherlands)

    Matova, S.P.; Elfrink, R.; Vullers, R.J.M.; Schaijk, R. van

    2011-01-01

    In this paper we report an airflow energy harvester that combines a piezoelectric energy harvester with a Helmholtz resonator. The resonator converts airflow energy to air oscillations which in turn are converted into electrical energy by a piezoelectric harvester. Two Helmholtz resonators with

  17. Airflow Test of Acoustic Board Samples

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Jensen, Lise Mellergaard

    In the laboratory of Indoor Environmental Engineering, Department of Civil Engineering, Aalborg University an airflow test on 2x10 samples of acoustic board were carried out the 2nd of June 2012. The tests were carried out for Rambøll and STO AG. The test includes connected values of volume flow...

  18. Airflow Obstruction and Use of Solid Fuels for Cooking or Heating: BOLD Results.

    Science.gov (United States)

    Amaral, André F S; Patel, Jaymini; Kato, Bernet S; Obaseki, Daniel O; Lawin, Hervé; Tan, Wan C; Juvekar, Sanjay K; Harrabi, Imed; Studnicka, Michael; Wouters, Emiel F M; Loh, Li-Cher; Bateman, Eric D; Mortimer, Kevin; Buist, A Sonia; Burney, Peter G J

    2017-09-12

    Evidence supporting the association of COPD or airflow obstruction with use of solid fuels is conflicting and inconsistent. To assess the association of airflow obstruction with self-reported use of solid fuels for cooking or heating. We analysed 18,554 adults from the BOLD study, who had provided acceptable post-bronchodilator spirometry measurements and information on use of solid fuels. The association of airflow obstruction with use of solid fuels for cooking or heating was assessed by sex, within each site, using regression analysis. Estimates were stratified by national income and meta-analysed. We carried out similar analyses for spirometric restriction, chronic cough and chronic phlegm. We found no association between airflow obstruction and use of solid fuels for cooking or heating (ORmen=1.20, 95%CI 0.94-1.53; ORwomen=0.88, 95%CI 0.67-1.15). This was true for low/middle and high income sites. Among never smokers there was also no evidence of an association of airflow obstruction with use of solid fuels (ORmen=1.00, 95%CI 0.57-1.76; ORwomen=1.00, 95%CI 0.76-1.32). Overall, we found no association of spirometric restriction, chronic cough or chronic phlegm with the use of solid fuels. However, we found that chronic phlegm was more likely to be reported among female never smokers and those who had been exposed for ≥20 years. Airflow obstruction assessed from post-bronchodilator spirometry was not associated with use of solid fuels for cooking or heating.

  19. Integrated building (and) airflow simulation: an overview

    NARCIS (Netherlands)

    Hensen, J.L.M.

    2002-01-01

    This paper aims to give a broad overview of building airflow simulation, and advocates that the essential ingredients for quality assurance are: domain knowledge; selection of appropriate level of resolution; calibration and validation; and a correct performance assessment methodology. Directions

  20. Entropy, Extropy and the Physical Driver of Irreversibility

    Directory of Open Access Journals (Sweden)

    Attila Grandpierre

    2012-06-01

    Full Text Available We point out that the fundamental irreversibility of Nature requires the introduction of a suitable measure for the distance from equilibrium. We show that entropy, which is widely held to be such a measure, suffers from the problem that it does not have a physical meaning, since it is introduced on the basis of mathematical arguments. As a consequence, the basic physics beyond irreversibility has remained obscure. We present here a simple but transparent physical approach for solving the problem of irreversibility. This approach shows that extropy, the fundamental thermodynamic variable introduced by Katalin Martinás, is the suitable measure for the distance from equilibrium, since it corresponds to the actual driver of irreversible processes. Since extropy explicitly contains in its definition all the general thermodynamic forces that drive irreversible processes, extropy is the suitable physical measure of irreversibility.

  1. Inhaled indacaterol for the treatment of COPD patients with destroyed lung by tuberculosis and moderate-to-severe airflow limitation: results from the randomized INFINITY study

    Directory of Open Access Journals (Sweden)

    Kim CJ

    2017-05-01

    study assessed the efficacy and safety of once-daily inhaled indacaterol 150 µg for the treatment of Korean COPD patients with destroyed lung by TB and moderate-to-severe airflow limitation. Methods: This was a multicenter, double-blind, parallel-group study, in which eligible patients were randomized (1:1 to receive either once-daily indacaterol 150 µg or placebo for 8 weeks. The primary efficacy endpoint was change from baseline in trough forced expiratory volume in 1 s at Week 8; the secondary endpoints included changes in transition dyspnea index score and St George’s Respiratory Questionnaire for COPD score at Week 8. Safety was evaluated over 8 weeks. Results: Of the 136 patients randomized, 119 (87.5% completed the study treatment. At Week 8, indacaterol significantly improved trough forced expiratory volume in 1 s versus placebo (treatment difference [TD] 140 mL, P<0.001. Statistically significant improvement in transition dyspnea index score (TD =0.78, P<0.05 and numerical improvement in St George’s Respiratory Questionnaire for COPD score (TD =-2.36, P=0.3563 were observed with indacaterol versus placebo at Week 8. Incidence of adverse events was comparable between the treatment groups. Conclusion: Indacaterol provided significantly superior bronchodilation, significant improvement in breathlessness and improved health status with comparable safety versus placebo in Korean COPD patients with destroyed lung by TB and moderate-to-severe airflow limitation. Keywords: indacaterol, COPD, tuberculosis, airflow limitation, lungs

  2. Thermal sensation and comfort during exposure to local airflow to face or legs.

    Science.gov (United States)

    Yamashita, Kazuaki; Matsuo, Juntaro; Tochihara, Yutaka; Kondo, Youichiro; Takayama, Shizuka; Nagayama, Hiroki

    2005-01-01

    The present study examined the contribution of local airflow temperature to thermal sensation and comfort in humans. Eight healthy male students were exposed to local airflow to their faces (summer condition) or legs (winter condition) for 30 minutes. Local airflow temperature (Tf) was maintained at 18 degrees C to 36 degrees C, and ambient temperature (Ta) was maintained at 17.4 degrees C to 31.4 degrees C. Each subject was exposed to 16 conditions chosen from the combination of Tf and Ta. Based on the results of multiple regression analysis, the standardized partial regression coefficient of Tf and Ta were determined to be 0.93 and 0.13 in the summer condition, and 0.71 and 0.36 in the winter condition at the end of the exposure. Also, thermal comfort was observed to depend closely on the interrelation between Tf and Ta. The present data suggested that local airflow temperature is an important thermal factor regarding thermal sensation and comfort.

  3. Effects of mass airflow rate through an open-circuit gas quantification system when measuring carbon emissions.

    Science.gov (United States)

    Gunter, Stacey A; Bradford, James A; Moffet, Corey A

    2017-01-01

    Methane (CH) and carbon dioxide (CO) represent 11 and 81%, respectively, of all anthropogenic greenhouse gas emissions. Agricultural CH emissions account for approximately 43% of all anthropogenic CH emissions. Most agricultural CH emissions are attributed to enteric fermentation within ruminant livestock; hence, the heightened interest in quantifying and mitigating this source. The automated, open-circuit gas quantification system (GQS; GreenFeed, C-Lock, Inc., Rapid City, SD) evaluated here can be placed in a pasture with grazing cattle and can measure their CH and CO emissions with spot sampling. However, improper management of the GQS can have an erroneous effect on emission estimates. One factor affecting the quality of emission estimates is the airflow rates through the GQS to ensure a complete capture of the breath cloud emitted by the animal. It is hypothesized that at lower airflow rates this cloud will be incompletely captured. To evaluate the effect of airflow rate through the GQS on emission estimates, a data set was evaluated with 758 CO and CH emission estimates with a range in airflows of 10.7 to 36.6 L/s. When airflow through the GQS was between 26.0 and 36.6 L/s, CO and CH emission estimates were not affected ( = 0.14 and 0.05, respectively). When airflow rates were less than 26.0 L/s, CO and CH emission estimates were lower and decreased as airflow rate decreased ( emissions are underestimated. Maintaining mass airflow through a GQS at rates greater than 26 L/s is important for producing high quality CO and CH emission estimates.

  4. Neuroethics with regard to treatment limiting and withdrawal of nutrition and hydration in long lasting irreversible full state apallic syndrome and minimal conscious state.

    Science.gov (United States)

    von Wild, Klaus

    2008-01-01

    Epidemiology in Europe shows constantly increasing figures for the Apallic Syndrome (AS)/Vegetative State (VS) as a consequence of advanced rescue, emergency services, intensive care treatment after acute brain damage, and high standard activating home nursing for completely dependent end stage cases secondary to progressive neurological disease. Management of patients in irreversible apallic syndrome has been the subject of sustained scientific and moral-legal debate over the last decade. Neuroethics coming more and more into consideration when neurological societies address key issues relating to AS/VS prevalence and quality management. With regard to treatment limiting and withdrawal of nutrition and hydration of patients suffering from irreversible full state Apallic Syndrome and Minimal Conscious State. The overall incidence of new AS/VS full stage cases all aetiology is 0.5 - 2/ 100.000 population per year. About one third is traumatic and two thirds are non-traumatic cases. The worst prognosis might be expected from nontraumatic hypoxemic apallic syndrome. The main conceptual criticism is based on assessment and diagnosis of all different AS/VS stages based solely on behavioural findings without knowing the exact or uniform pathogenesis or neuropathologic findings. No special diagnostics, no specific medical management can be recommended for class II or III AS treatment and rehabilitation. But in United Kingdom, The Netherlands, Belgium, and Switzerland active euthanasia is now practiced in medicine taking into account the uncertainty of the right diagnose the clinical features for humanistic treatment of patients in irreversible "AS full or early, remission stages". As long as there is no single AS/VS specific diagnostic tool, no specific laboratory investigation regimen to be recommended neuroethical principles demands by all means a humanistic (ethical) activating nursing even in the irreversible full stage AS cases. Full acceptable is only the palliative

  5. Interleukin-6 and airflow limitation in chemical warfare patients with chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Davood Attaran

    2010-09-01

    Full Text Available Davood Attaran1, Shahrzad M Lari1, Mohammad Towhidi1, Hassan Ghobadi Marallu2, Hossein Ayatollahi1, Mohammad Khajehdaluee1, Mostafa Ghanei3, Reza Basiri11Lung Disease and Tuberculosis Research Center, Mashhad University of Medical Science, 2Ardabil University of Medical Sciences, 3Research Center of Chemical Injuries, Baqiyatallah University of Medical Sciences, Tehran, IranObjectives: Chronic obstructive pulmonary disease (COPD is one of the main late complications of sulfur mustard poisoning. The aim of this study was to evaluate serum levels of interleukin (IL-6 in war veterans with pulmonary complications of sulfur mustard poisoning and their correlation with severity of airways disease.Methods: Fifty consecutive patients with sulfur mustard poisoning and stable COPD, and of mean age 46.3 ± 9.18 years were enrolled in this study. Thirty healthy men were selected as controls and matched to cases by age and body mass index. Spirometry, arterial blood gas, six-minute walk test, BODE (body mass index, obstruction, dyspnea, and exercise capacity, and St George’s Respiratory Questionnaire about quality of life were evaluated. Serum IL-6 was measured in both patient and control groups.Results: Fifty-four percent of patients had moderate COPD. Mean serum IL-6 levels were 15.01 ± standard deviation (SD 0.61 pg/dL and 4.59 ± 3.40 pg/dL in the case and control groups, respectively (P = 0.03. There was a significant correlation between IL-6 levels and Global Initiative for Chronic Obstructive Lung Disease stage (r = 0.25, P = 0.04 and between IL-6 and BODE index (r = 0.38, P = 0.01. There was also a significant negative correlation between serum IL-6 and forced expiratory volume in one second (FEV1, r = -0.36, P = 0.016.Conclusion: Our findings suggest that serum IL-6 is increased in patients with sulfur mustard poisoning and COPD, and may have a direct association with airflow limitation.Keywords: sulfur mustard, chronic obstructive pulmonary

  6. Airflow resistivity instrument for in situ measurement on the earth's ground surface

    Science.gov (United States)

    Zuckerwar, A. J.

    1983-01-01

    An airflow resistivity instrument features a novel specimen holder, especially designed for in situ measurement on the earth's ground surface. This capability eliminates the disadvantages of prior intrusive instruments, which necessitate the removal of a test specimen from the ground. A prototype instrument can measure airflow resistivities in the range 10-5000 cgs rayl/cm, at specimen depths up to 15.24 cm (6 in.), and at differential pressures up to 2490.8 dyn sq cm (1 in. H2O) across the specimen. Because of the close relationship between flow resistivity and acoustic impedance, this instrument should prove useful in acoustical studies of the earth's ground surface. Results of airflow resistivity measurements on an uncultivated grass field for varying values of moisture content are presented.

  7. Proportion and clinical characteristics of non-asthmatic non-smokers among adults with airflow obstruction.

    Science.gov (United States)

    Takiguchi, Hiroto; Takeuchi, Tomoe; Niimi, Kyoko; Tomomatsu, Hiromi; Tomomatsu, Katsuyoshi; Hayama, Naoki; Oguma, Tsuyoshi; Aoki, Takuya; Urano, Tetsuya; Asai, Satomi; Miyachi, Hayato; Asano, Koichiro

    2018-01-01

    Chronic obstructive pulmonary disease (COPD) mainly develops after long-term exposure to cigarette or biomass fuel smoke, but also occurs in non-smokers with or without a history of asthma. We investigated the proportion and clinical characteristics of non-smokers among middle-aged to elderly subjects with airflow obstruction. We retrospectively analyzed 1,892 subjects aged 40-89 years who underwent routine preoperative spirometry at a tertiary university hospital in Japan. Airflow obstruction was defined as a forced expiratory volume in 1 second (FEV1)/forced vital capacity non-asthmatic patients with airflow obstruction, 94 (34%) were non-smokers. A larger number of women than men with airflow obstruction had asthma (26% vs. 7.6%, p non-smokers among non-asthmatics (72% vs. 20%, p Non-asthmatic non-smokers, rather than non-asthmatic smokers, asthmatic non-smokers, and asthmatic smokers, exhibited better pulmonary function (median FEV1: 79% of predicted FEV1 vs. 73%, 69%, and 66%, respectively, p = 0.005) and less dyspnea on exertion (1% vs. 12%, 12%, and 28%, respectively, p = 0.001). Pulmonary emphysema on thoracic computed tomography was less common in non-smokers (p non-smokers with airflow obstruction compatible with COPD in Japan. In this study, airflow obstruction in non-smokers was more common in women and likelier to result in mild functional and pathological abnormalities than in smokers. Further studies are warranted to investigate the long-term prognosis and appropriate management of this population in developed countries, especially in women.

  8. Finite Element Modeling of Airflow During Phonation

    Czech Academy of Sciences Publication Activity Database

    Šidlof, P.; Lunéville, E.; Chambeyron, C.; Doaré, O.; Chaigne, A.; Horáček, Jaromír

    2010-01-01

    Roč. 4, č. 1 (2010), s. 121-132 ISSN 1802-680X R&D Projects: GA AV ČR KJB200760801 Institutional research plan: CEZ:AV0Z20760514 Keywords : vocal fold s * airflow * numerical modeling * ALE * flow separation Subject RIV: BI - Acoustics

  9. Scoliosis associated with airflow obstruction due to endothoracic vertebral hump.

    Science.gov (United States)

    Ito, Kenyu; Kawakami, Noriaki; Miyasaka, Kazuyoshi; Tsuji, Taichi; Ohara, Tetsuya; Nohara, Ayato

    2012-12-01

    A retrospective clinical study of scoliosis-associated airflow obstruction due to endothoracic vertebral hump. The purpose of this study was to evaluate and present anatomical features of patients with scoliosis who showed airflow obstruction caused by endothoracic vertebral hump. It is well known that severe scoliosis causes airflow restriction due to thoracic cage deformity. There have been few reports of clinical data and anatomical features on scoliosis associated with airflow obstruction due to endothoracic vertebral hump. The subjects were 6 patients. The diagnoses were idiopathic scoliosis in 3 patients, symptomatic scoliosis in 2 patients, and thoracogenic scoliosis in 1 patient. The radiological outcome, comorbidities, pre- and postoperative respiratory function, and surgical complication were analyzed. Four patients had preoperative atelectasis on the convex side of the lower lobe and improved after the operations. All patients showed main thoracic curves and their apex was located at T7-T9. All patients had lordoscoliosis except 1, who demonstrated kyphosing scoliosis. The correction rate was 78% (62.8%-83.5%). Preoperative thoracic lordosis within the range of -5° to -47° was postoperatively corrected to a substantially normal kyphosis within the range of 9° to 24°. The average vital capacity, percent VC improved from 0.72 L (0.33-1.17 L) to 1.21 L (0.82-1.71 L) and 45.5% (37.3%- 50.8%) to 63.7% (41.0%-88.6%) relatively. Spine Penetration Index improved from 23% (18%-35%) to 16% (13%-19%). Endothoracic hump ratio improved from 1.34 (0.98-1.93) to 1.12 (0.86-1.28). Each patient with symptomatic scoliosis and thoracogenic scoliosis required relatively long periods of respiration management. Patients having lordoscoliosis with an apex located between T7 and T9 may develop airflow obstruction due to an endothoracic vertebral hump. Correction of lordoscoliosis through anterior and posterior approaches successfully improved endothoracic hump ratio and

  10. Irreversible dynamics, Onsager-Casimir symmetry, and an application to turbulence.

    Science.gov (United States)

    Ottinger, Hans Christian

    2014-10-01

    Irreversible contributions to the dynamics of nonequilibrium systems can be formulated in terms of dissipative, or irreversible, brackets. We discuss the structure of such irreversible brackets in view of a degeneracy implied by energy conservation, where we consider different types of symmetries of the bracket corresponding to the Onsager and Casimir symmetries of linear irreversible thermodynamics. Slip and turbulence provide important examples of antisymmetric irreversible brackets and offer guidance for the more general modeling of irreversible dynamics without entropy production. Conversely, turbulence modeling could benefit from elucidating thermodynamic structure. The examples suggest constructing antisymmetric irreversible brackets in terms of completely antisymmetric functions of three indices. Irreversible brackets without well-defined symmetry properties can arise for rare events, causing big configurational changes.

  11. Coupling fast fluid dynamics and multizone airflow models in Modelica Buildings library to simulate the dynamics of HVAC systems

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Wei [Univ. of Miami, FL (United States). Dept. of Civil, Architectural and Environmental Engineering; Sevilla, Thomas Alonso [Univ. of Miami, FL (United States). Dept. of Civil, Architectural and Environmental Engineering; Zuo, Wangda [Univ. of Miami, FL (United States). Dept. of Civil, Architectural and Environmental Engineering; Sohn, Michael D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Analysis and Environmental Impacts Div.

    2017-06-08

    Historically, multizone models are widely used in building airflow and energy performance simulations due to their fast computing speed. However, multizone models assume that the air in a room is well mixed, consequently limiting their application. In specific rooms where this assumption fails, the use of computational fluid dynamics (CFD) models may be an alternative option. Previous research has mainly focused on coupling CFD models and multizone models to study airflow in large spaces. While significant, most of these analyses did not consider the coupled simulation of the building airflow with the building's Heating, Ventilation, and Air-Conditioning (HVAC) systems. This paper tries to fill the gap by integrating the models for HVAC systems with coupled multizone and CFD simulations for airflows, using the Modelica simul ation platform. To improve the computational efficiency, we incorporated a simplified CFD model named fast fluid dynamics (FFD). We first introduce the data synchronization strategy and implementation in Modelica. Then, we verify the implementation using two case studies involving an isothermal and a non-isothermal flow by comparing model simulations to experiment data. Afterward, we study another three cases that are deemed more realistic. This is done by attaching a variable air volume (VAV) terminal box and a VAV system to previous flows to assess the capability of the models in studying the dynamic control of HVAC systems. Finally, we discuss further research needs on the coupled simulation using the models.

  12. Computational fluid dynamics study on the influence of airflow patterns on carbon dioxide distribution in a scaled livestock building

    DEFF Research Database (Denmark)

    Rong, Li; Nielsen, P V; Tong, G

    2008-01-01

    building with slatted floor. Contaminant sources are assumed to be modelled as a constant concentration on the manure surface. Three different ventilation rates and two different deflector degrees are studied, in which the deflector is applied to change the airflow patterns. A CFD commercial software code......Airflow patterns and airflow rate have an important influence on contaminant distribution in livestock buildings. The objective of this paper is to model and evaluate the effect of airflow rates and airflow patterns effect on CO2 concentration distribution and emission rates in a scaled livestock...

  13. Difference in airflow obstruction between Hispanic and non-Hispanic White female smokers.

    Science.gov (United States)

    Sood, Akshay; Stidley, Christine A; Picchi, Maria A; Celedón, Juan C; Gilliland, Frank; Crowell, Richard E; Belinsky, Steven A; Tesfaigzi, Yohannes

    2008-10-01

    Smoking-related respiratory diseases are a major cause of morbidity and mortality. However, the relationship between smoking and respiratory disease has not been well-studied among ethnic minorities in general and among women in particular. The objective of this cross-sectional study was to evaluate the risk of airflow obstruction and to assess lung function among Hispanic and non-Hispanic White (NHW) female smokers in a New Mexico cohort. Participants completed a questionnaire detailing smoking history and underwent spirometry testing. Outcomes studied included airflow obstruction, selected lung function parameters, and chronic mucus hyper-secretion. Chi square, logistic, and linear regression techniques were utilized. Of the 1,433 eligible women participants, 248 (17.3%) were Hispanic; and 319 had airflow obstruction (22.3%). Hispanic smokers were more likely to be current smokers, and report lower pack-years of smoking, compared to NHW smokers (p smokers were at a reduced risk of airflow obstruction compared to NHW smokers, with an O.R. of 0.51, 95% C.I. 0.34, 0.78 (p = 0.002) after adjustment for age, BMI, pack-years and duration of smoking, and current smoking status. Following adjustment for covariates, Hispanic smokers also had a higher mean absolute and percent predicted post-bronchodilator FEV(1)/FVC ratio, as well as higher mean percent predicted FEV(1) (p smokers in this New Mexico-based cohort had lower risk of airflow obstruction and better lung function than NHW female smokers. Further, smoking history did not completely explain these associations.

  14. Bacterial burden in the operating room: impact of airflow systems.

    Science.gov (United States)

    Hirsch, Tobias; Hubert, Helmine; Fischer, Sebastian; Lahmer, Armin; Lehnhardt, Marcus; Steinau, Hans-Ulrich; Steinstraesser, Lars; Seipp, Hans-Martin

    2012-09-01

    Wound infections present one of the most prevalent and frequent complications associated with surgical procedures. This study analyzes the impact of currently used ventilation systems in the operating room to reduce bacterial contamination during surgical procedures. Four ventilation systems (window-based ventilation, supported air nozzle canopy, low-turbulence displacement airflow, and low-turbulence displacement airflow with flow stabilizer) were analyzed. Two hundred seventy-seven surgical procedures in 6 operating rooms of 5 different hospitals were analyzed for this study. Window-based ventilation showed the highest intraoperative contamination (13.3 colony-forming units [CFU]/h) followed by supported air nozzle canopy (6.4 CFU/h; P = .001 vs window-based ventilation) and low-turbulence displacement airflow (3.4 and 0.8 CFU/h; P system showed no increase of contamination in prolonged durations of surgical procedures. This study shows that intraoperative contamination can be significantly reduced by the use of adequate ventilation systems. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  15. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran; Vuong, Francois; Hu, Jingyi; Li, Sheng; Kemperman, Antoine J.B.; Nijmeijer, Kitty; Cornelissen, Emile R.; Heijman, Sebastiaan G.J.; Rietveld, Luuk C.

    2015-01-01

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  16. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran

    2015-05-06

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  17. Irreversible electroporation: state of the art

    Directory of Open Access Journals (Sweden)

    Wagstaff PGK

    2016-04-01

    Full Text Available Peter GK Wagstaff,1 Mara Buijs,1 Willemien van den Bos,1 Daniel M de Bruin,2 Patricia J Zondervan,1 Jean JMCH de la Rosette,1 M Pilar Laguna Pes1 1Department of Urology, 2Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands Abstract: The field of focal ablative therapy for the treatment of cancer is characterized by abundance of thermal ablative techniques that provide a minimally invasive treatment option in selected tumors. However, the unselective destruction inflicted by thermal ablation modalities can result in damage to vital structures in the vicinity of the tumor. Furthermore, the efficacy of thermal ablation intensity can be impaired due to thermal sink caused by large blood vessels in the proximity of the tumor. Irreversible electroporation (IRE is a novel ablation modality based on the principle of electroporation or electropermeabilization, in which electric pulses are used to create nanoscale defects in the cell membrane. In theory, IRE has the potential of overcoming the aforementioned limitations of thermal ablation techniques. This review provides a description of the principle of IRE, combined with an overview of in vivo research performed to date in the liver, pancreas, kidney, and prostate. Keywords: irreversible electroporation, IRE, tumor, ablation, focal therapy, cancer

  18. Proportion and clinical characteristics of non-asthmatic non-smokers among adults with airflow obstruction

    Science.gov (United States)

    Takiguchi, Hiroto; Takeuchi, Tomoe; Niimi, Kyoko; Tomomatsu, Hiromi; Tomomatsu, Katsuyoshi; Hayama, Naoki; Oguma, Tsuyoshi; Urano, Tetsuya; Asai, Satomi; Miyachi, Hayato; Asano, Koichiro

    2018-01-01

    Background and objectives Chronic obstructive pulmonary disease (COPD) mainly develops after long-term exposure to cigarette or biomass fuel smoke, but also occurs in non-smokers with or without a history of asthma. We investigated the proportion and clinical characteristics of non-smokers among middle-aged to elderly subjects with airflow obstruction. Methods We retrospectively analyzed 1,892 subjects aged 40–89 years who underwent routine preoperative spirometry at a tertiary university hospital in Japan. Airflow obstruction was defined as a forced expiratory volume in 1 second (FEV1)/forced vital capacity non-asthmatic patients with airflow obstruction, 94 (34%) were non-smokers. A larger number of women than men with airflow obstruction had asthma (26% vs. 7.6%, p non-smokers among non-asthmatics (72% vs. 20%, p Non-asthmatic non-smokers, rather than non-asthmatic smokers, asthmatic non-smokers, and asthmatic smokers, exhibited better pulmonary function (median FEV1: 79% of predicted FEV1 vs. 73%, 69%, and 66%, respectively, p = 0.005) and less dyspnea on exertion (1% vs. 12%, 12%, and 28%, respectively, p = 0.001). Pulmonary emphysema on thoracic computed tomography was less common in non-smokers (p non-smokers with airflow obstruction compatible with COPD in Japan. In this study, airflow obstruction in non-smokers was more common in women and likelier to result in mild functional and pathological abnormalities than in smokers. Further studies are warranted to investigate the long-term prognosis and appropriate management of this population in developed countries, especially in women. PMID:29742176

  19. Experimental study on airflow fluctuation characteristic of an underfloor air supply terminal unit

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinping [School of Electric Power, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou 510640 (China); Wu, Yanfang [Design Institute of Guangzhou Metro Corporation, Guangzhou 510010 (China)

    2010-11-15

    In order to investigate dynamic characteristic of underfloor air supply terminal unit, an IFV900A hot-wire anemometer was used to measure the corresponding velocity field. Turbulence intensity and power spectrum density exponent of air velocity signal were analyzed. The result showed that the outlet velocity distribution of underfloor air supply terminal unit was uniform. With increment of height, the velocity distribution trends to be uniform. Two velocity attenuation regions appear during airflow development. Turbulence intensity changes obviously with height. It is lower than that of mechanical wind. Turbulence intensity goes up with the increment of jetting distance. Power spectrum density exponent trends to the value of natural wind with increase of jetting distance and decrease of wind velocity. The exponent value approaches to the value of typical natural wind for the air velocity is 0.5 m/s under high supply air rate. With airflow diffusion, the fluctuation characteristic of airflow varies obviously with the jetting direction. The fluctuation characteristic of airflow changes to that of natural wind with the increase of height which can improve comfort of indoor environment. (author)

  20. Statistical mechanics out of equilibrium the irreversibility

    International Nuclear Information System (INIS)

    Alvarez Estrada, R. F.

    2001-01-01

    A Round Table about the issue of Irreversibility and related matters has taken place during the last (20th) Statistical Mechanics Conference, held in Paris (July 1998). This article tries to provide a view (necessarily limited, and hence, uncompleted) of some approaches to the subject: the one based upon deterministic chaos (which is currently giving rise to a very active research) and the classical interpretation due to Boltzmann. An attempt has been made to write this article in a self-contained way, and to avoid a technical presentation wherever possible. (Author) 29 refs

  1. Harvesting energy from airflow with a michromachined piezoelectric harvester inside a Helmholtz resonator

    International Nuclear Information System (INIS)

    Matova, S P; Elfrink, R; Vullers, R J M; Van Schaijk, R

    2011-01-01

    In this paper we report an airflow energy harvester that combines a piezoelectric energy harvester with a Helmholtz resonator. The resonator converts airflow energy to air oscillations which in turn are converted into electrical energy by a piezoelectric harvester. Two Helmholtz resonators with adjustable resonance frequencies have been designed—one with a solid bottom and one with membrane on the bottom. The resonance frequencies of the resonators were matched to the complementing piezoelectric harvesters during harvesting. The aim of the presented work is a feasibility study on using packaged piezoelectric energy harvesters with Helmholtz resonators for airflow energy harvesting. The maximum energy we were able to obtain was 42.2 µW at 20 m s −1

  2. Irreversible colloidal agglomeration in presence of associative inhibitors: Computer simulation study

    International Nuclear Information System (INIS)

    Barcenas, Mariana; Duda, Yurko

    2007-01-01

    Monte Carlo simulation is employed to study the irreversible particle-cluster agglomeration of valence-limited colloids affected by associative inhibitors. The cluster size distribution and number of connections between colloids are analyzed as a function of density and inhibitor concentration. The influence of colloid functionality on its aggregation is discussed

  3. Irreversibility and dissipation in finite-state automata

    International Nuclear Information System (INIS)

    Ganesh, Natesh; Anderson, Neal G.

    2013-01-01

    Irreversibility and dissipation in finite-state automata (FSA) are considered from a physical-information-theoretic perspective. A quantitative measure for the computational irreversibility of finite automata is introduced, and a fundamental lower bound on the average energy dissipated per state transition is obtained and expressed in terms of FSA irreversibility. The irreversibility measure and energy bound are germane to any realization of a deterministic automaton that faithfully registers abstract FSA states in distinguishable states of a physical system coupled to a thermal environment, and that evolves via a sequence of interactions with an external system holding a physical instantiation of a random input string. The central result, which is shown to follow from quantum dynamics and entropic inequalities alone, can be regarded as a generalization of Landauer's Principle applicable to FSAs and tailorable to specified automata. Application to a simple FSA is illustrated.

  4. Extended Irreversible Thermodynamics

    CERN Document Server

    Jou, David

    2010-01-01

    This is the 4th edition of the highly acclaimed monograph on Extended Irreversible Thermodynamics, a theory that goes beyond the classical theory of irreversible processes. In contrast to the classical approach, the basic variables describing the system are complemented by non-equilibrium quantities. The claims made for extended thermodynamics are confirmed by the kinetic theory of gases and statistical mechanics. The book covers a wide spectrum of applications, and also contains a thorough discussion of the foundations and the scope of the current theories on non-equilibrium thermodynamics. For this new edition, the authors critically revised existing material while taking into account the most recent developments in fast moving fields such as heat transport in micro- and nanosystems or fast solidification fronts in materials sciences. Several fundamental chapters have been revisited emphasizing physics and applications over mathematical derivations. Also, fundamental questions on the definition of non-equil...

  5. Attribution of irreversible loss to anthropogenic climate change

    Science.gov (United States)

    Huggel, Christian; Bresch, David; Hansen, Gerrit; James, Rachel; Mechler, Reinhard; Stone, Dáithí; Wallimann-Helmer, Ivo

    2016-04-01

    The Paris Agreement (2015) under the UNFCCC has anchored loss and damage in a separate article which specifies that understanding and support should be enhanced in areas addressing loss and damage such as early warning, preparedness, insurance and resilience. Irreversible loss is a special category under loss and damage but there is still missing clarity over what irreversible loss actually includes. Many negative impacts of climate change may be handled or mitigated by existing risk management, reduction and absorption approaches. Irreversible loss, however, is thought to be insufficiently addressed by risk management. Therefore, countries potentially or actually affected by irreversible loss are calling for other measures such as compensation, which however is highly contested in international climate policy. In Paris (2015) a decision was adopted that loss and damage as defined in the respective article of the agreement does not involve compensation and liability. Nevertheless, it is likely that some sort of mechanism will eventually need to come into play for irreversible loss due to anthropogenic climate change, which might involve compensation, other forms of non-monetary reparation, or transformation. Furthermore, climate litigation has increasingly been attempted to address negative effects of climate change. In this context, attribution is important to understand the drivers of change, what counts as irreversible loss due to climate change, and, possibly, who or what is responsible. Here we approach this issue by applying a detection and attribution perspective on irreversible loss. We first analyze detected climate change impacts as assessed in the IPCC Fifth Assessment Report. We distinguish between irreversible loss in physical, biological and human systems, and accordingly identify the following candidates of irreversible loss in these systems: loss of glaciers and ice sheets, loss of subsurface ice (permafrost) and related loss of lake systems; loss

  6. Clinically remitted childhood asthma is associated with airflow obstruction in middle-aged adults.

    Science.gov (United States)

    Omori, Keitaro; Iwamoto, Hiroshi; Yamane, Takashi; Nakashima, Taku; Haruta, Yoshinori; Hattori, Noboru; Yokoyama, Akihito; Kohno, Nobuoki

    2017-01-01

    While adult asthma has been shown to be a risk factor for COPD, the effect of remitted childhood asthma on adult lung function has not been clarified. The aim of this study was to examine whether remitted childhood asthma is a risk factor for airflow obstruction in a middle-aged general population. A total of 9896 participants (range: 35-60 years) from five healthcare centres were included in the study. The participants were classified into four categories based on the presence or absence of physician-diagnosed childhood/adulthood asthma and asthma symptoms as follows: healthy controls (n = 9154), remitted childhood asthma (n = 287), adulthood-onset asthma (n = 354) and childhood-adulthood asthma (n = 101). The prevalence of respiratory symptoms was similar in both the participants with remitted childhood asthma and healthy controls. The prevalence of airflow obstruction (forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) childhood asthma, those with adult-onset asthma and those with childhood-adulthood asthma (5.2%, 14.4% and 16.8%, respectively) compared with healthy controls (2.2%). Multivariate logistic regression showed that remitted childhood asthma was independently associated with airflow obstruction. Among the participants with remitted childhood asthma, ever-smokers had significantly lower FEV 1 /FVC than never-smokers. Clinically remitted childhood asthma is associated with airflow obstruction in middle-aged adults. Smoking and remitted childhood asthma may be additive factors for the development of airflow obstruction. © 2016 Asian Pacific Society of Respirology.

  7. Effect of disinfection on irreversible hydrocolloid and alternative impression materials and the resultant gypsum casts.

    Science.gov (United States)

    Suprono, Montry S; Kattadiyil, Mathew T; Goodacre, Charles J; Winer, Myron S

    2012-10-01

    Many new products have been introduced and marketed as alternatives to traditional irreversible hydrocolloid materials. These alternative materials have the same structural formula as addition reaction silicone, also known as vinyl polysiloxane (VPS), impression materials. Currently, there is limited in vitro and in vivo research on these products, including on the effects of chemical disinfectants on the materials. The purpose of this study was to compare the effects of a spray disinfecting technique on a traditional irreversible hydrocolloid and 3 new alternative impression materials in vitro. The tests were performed in accordance with the American National Standards Institute/American Dental Association (ANSI/ADA) Specification Nos. 18 and 19. Under standardized conditions, 100 impressions were made of a ruled test block with an irreversible hydrocolloid and 3 alternative impression materials. Nondisinfected irreversible hydrocolloid was used as the control. The impressions were examined for surface detail reproduction before and after disinfection with a chloramine-T product. Type III and Type V dental stone casts were evaluated for linear dimensional change and gypsum compatibility. Comparisons of linear dimensional change were analyzed with 2-way ANOVA of mean ranks with the Scheffé post hoc comparisons (α=.05). Data for surface detail reproduction were analyzed with the Wilcoxon Signed-Rank procedure and gypsum compatibility with the Kruskal-Wallis Rank procedure (α=.05). The alternative impression materials demonstrated significantly better outcomes with all 3 parameters tested. Disinfection with chloroamine-T did not have any effect on the 3 alternative impression materials. The irreversible hydrocolloid groups produced the most variability in the measurements of linear dimensional change. All of the tested materials were within the ADA's acceptable limit of 1.0% for linear dimensional change, except for the disinfected irreversible hydrocolloid

  8. Is there any relationship between right and left hand dominance and right and left nasal airflow dominance?

    Science.gov (United States)

    Price, A; Eccles, R

    2017-10-01

    Left- or right-handedness is a common human trait, and it has been previously reported that human nasal airflow dominance correlates with hand dominance. Any relationship between hand dominance and nasal airflow dominance would be unusual. This study aimed to measure nasal airflow and look for any relationship to handedness. The modified Glatzel mirror was used to record the dominant nasal passage at 15-minute intervals over a 6-hour period in 29 healthy participants consisting of 15 left-handers and 14 right-handers. In left-handers, the percentage of time that the left nasal passage was dominant ranged from 0 to 100 per cent. In right-handers, the percentage of time that the right nasal passage was dominant ranged from 4.2 to 95.8 per cent. No correlation between nasal airflow dominance and hand dominance was identified. The results do not support the hypothesis that nasal airflow and handedness are related.

  9. Airflow resistivity of models of fibrous acoustic materials

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    1996-01-01

    A new way of calculating the airflow resistivity of randomly placed parallel cylinders is presented. The calculation is based on Voronoi polygons, and the resistivity is given by the mean spacing between the fibers, their diameters, and the physical properties of air. New explicit formulas...

  10. Investigation of airflow patterns in a microclimate by particle image velocimetry (PIV)

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Rode, Carsten; Peuhkuri, Ruut

    2008-01-01

    Problems with mould growth in dwellings usually occur in bedrooms in the microclimate behind closets placed next to exterior walls with poor insulation. It is anticipated that the problems are caused by lack of airflow behind the furniture in combination with a colder surface temperature and a high...... that the flow rates behind the furniture will increase with increased distance between the closet and the wall, and even higher airflow rates are seen when the furniture is elevated by legs....

  11. Development of an Indoor Airflow Energy Harvesting System for Building Environment Monitoring

    Directory of Open Access Journals (Sweden)

    Fei Fei

    2014-05-01

    Full Text Available Wireless sensor networks (WSNs have been widely used for intelligent building management applications. Typically, indoor environment parameters such as illumination, temperature, humidity and air quality are monitored and adjusted by an intelligent building management system. However, owing to the short life-span of the batteries used at the sensor nodes, the maintenance of such systems has been labor-intensive and time-consuming. This paper discusses a battery-less self-powering system that converts the mechanical energy from the airflow in ventilation ducts into electrical energy. The system uses a flutter energy conversion device (FECD capable of working at low airflow speeds while installed on the ventilation ducts inside of buildings. A power management strategy implemented with a circuit system ensures sufficient power for driving commercial electronic devices. For instance, the power management circuit is capable of charging a 1 F super capacitor to 2 V under ventilation duct airflow speeds of less than 3 m/s.

  12. Climate chamber for environmentally controlled laboratory airflow experiments.

    Science.gov (United States)

    Even-Tzur, Nurit; Zaretsky, Uri; Grinberg, Orly; Davidovich, Tomer; Kloog, Yoel; Wolf, Michael; Elad, David

    2010-01-01

    Climate chambers have been widely used in in vitro and in vivo studies which require controlled environmental temperature and humidity conditions. This article describes a new desktop climate chamber that was developed for application of respiratory airflows on cultured nasal epithelial cells (NEC) under controlled temperature and humidity conditions. Flow experiments were performed by connecting the climate chamber to an airflow generator via a flow chamber with cultured NEC. Experiments at two controlled climate conditions, 25 degrees C and 40% relative humidity (RH) and 37 degrees C and 80%RH, were conducted to study mucin secretion from the cultures inresponse to the flow. The new climate chamber is a relatively simple and inexpensive apparatus which can easily be connected to any flow system for climate controlled flow experiments. This chamber can be easily adjusted to various in vitro experiments, as well as to clinical studies with animals or human subjects which require controlled climate conditions.

  13. Interferon-gamma improves impaired dentinogenic and immunosuppressive functions of irreversible pulpitis-derived human dental pulp stem cells

    OpenAIRE

    Soichiro Sonoda; Haruyoshi Yamaza; Lan Ma; Yosuke Tanaka; Erika Tomoda; Reona Aijima; Kazuaki Nonaka; Toshio Kukita; Songtao Shi; Fusanori Nishimura; Takayoshi Yamaza

    2016-01-01

    Clinically, irreversible pulpitis is treated by the complete removal of pulp tissue followed by replacement with artificial materials. There is considered to be a high potential for autologous transplantation of human dental pulp stem cells (DPSCs) in endodontic treatment. The usefulness of DPSCs isolated from healthy teeth is limited. However, DPSCs isolated from diseased teeth with irreversible pulpitis (IP-DPSCs) are considered to be suitable for dentin/pulp regeneration. In this study, we...

  14. Statistical data analysis method for multi-zonal airflow measurement using multiple kinds of perfluorocarbon tracer gas

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, Hiroyasu; Onishi, Yoshinori [Institute of Technology, Shimizu Corporation, 4-17, Etchujima 3-chome, Koto-ku, Tokyo 135-8530 (Japan); Tanabe, Shin-ichi [School of Science and Engineering, Department of Architecture, Waseda University, 3-4-1 Okubo, Shinjyuku-ku, Tokyo 169-8555 (Japan); Kashihara, Seiichi [R and D Laboratories, Asahi Kasei Homes Corporation, 2-1, Samejima Fuji-shi, Shizuoka 416-8501 (Japan)

    2009-03-15

    Conventional multi-zonal ventilation measurement methods by multiple types of perfluorocarbon tracers use a number of different gases equal to the number of zones (n). The possible n x n+n airflows are estimated from the mass balance of the gases and the airflow balance. However, some airflows may not occur because of inter-zonal geometry, and the introduction of unnecessary, unknown parameters can impair the accuracy of the estimation. Also, various error factors often yield an irrational negative airflow rate. Conventional methods are insufficient for the evaluation of error. This study describes a way of using the least-squares technique to improve the precision of estimation and to evaluate reliability. From the equations' residual, the error variance-covariance matrix {lambda}{sub q} of the estimated airflow rate error is deduced. In addition, the coefficient of determinant using the residual sum of squares and total variation is introduced. Furthermore, the error matrix{sub m}{lambda}{sub q} from the measurement errors in the gas concentration and gas emission rate is deduced. The discrepancy ratio of the model premises is defined by dividing the diagonal elements of the former by those of the latter. Moreover, the index of irrationality of the estimated negative airflow rate is defined, based on the different results of the three estimation methods. Some numerical experiments are also carried out to verify the flow rate estimation and the reliability evaluation theory. (author)

  15. Airflow characteristics and pollution distribution around a thermal manikin - Impact of specific personal and indoor environmental factors

    DEFF Research Database (Denmark)

    Licina, Dusan; Tham, Kwok Wai; Melikov, Arsen Krikor

    2016-01-01

    , and ventilation flow considerably affected airflow characteristics and pollution distribution around the thermal manikin. Under the specific set of conditions studied, the most favorable airflow patterns in preventing the feet pollution from reaching the breathing zone was transverse flow from the front......This study presents a summary of experimental measurements on the airflow characteristics and pollution distribution around a non-breathing thermal manikin. The two objectives are: (1) to examine the extent to which personal (body posture, clothing insulation, table positioning) and environmental...... factors (room air temperature and ventilation flow) affect the airflow characteristic (velocity and temperature) around the thermal manikin and (2) to examine the pollution distribution within the convective boundary layer (CBL) around a thermal manikin and personal exposure to two types of airborne...

  16. Chronic airflow limitation in a rural Indian population: etiology and relationship to body mass index

    Directory of Open Access Journals (Sweden)

    Chakrabarti B

    2011-10-01

    Full Text Available Biswajit Chakrabarti1, Sabita Purkait2, Punyabrata Gun2, Vicky C Moore3, Samadrita Choudhuri4, MJ Zaman5,6, Christopher J Warburton1, Peter MA Calverley7, Rahul Mukherjee3 1Aintree Chest Centre, University Hospital Aintree, Liverpool, UK; 2Moitri Swasthya Kendra, Shramajibi Swasthya Udyog, Chengail, West Bengal, India; 3Department of Respiratory Medicine and Physiology, Birmingham Heartlands Hospital, Birmingham, UK; 4National Medical College, Birgunj, Nepal; 5Department of Epidemiology and Public Health, University College, London, UK; 6The George Institute for Global Health, Sydney, Australia; 7Clinical Sciences Centre, University Hospital Aintree, Liverpool, UK Purpose: Respiratory conditions remain a source of morbidity globally. As such, this study aimed to explore factors associated with the development of airflow obstruction (AFO in a rural Indian setting and, using spirometry, study whether underweight is linked to AFO. Methods: Patients > 35 years old attending a rural clinic in West Bengal, India, took a structured questionnaire, had their body mass index (BMI measured, and had spirometry performed by an ancillary health care worker. Results: In total, 416 patients completed the study; spirometry was acceptable for analysis of forced expiratory volume in 1 second in 286 cases (69%; 16% were noted to exhibit AFO. Factors associated with AFO were: increasing age (95% confidence interval (CI 0.004–0.011; P = 0.005, smoking history (95% CI 0.07–0.174; P = 0.006, male gender (95% CI 0.19–0.47; P = 0.012, reduced BMI (95% CI 0.19–0.65; P = 0.02, and occupation (95% CI 0.12–0.84; P = 0.08. The mean BMI in males who currently smoked (n = 60; 19.29 kg/m2; standard deviation [SD] 3.46 was significantly lower than in male never smokers (n = 33; 21.15 kg/m2 SD 3.38; P < 0.001. AFO was observed in 27% of subjects with a BMI <18.5 kg/m2, falling to 13% with a BMI ≥18.5 kg/m2 (P = 0.013. AFO was observed in 11% of housewives, 22% of farm

  17. Generalized irreversible heat-engine experiencing a complex heat-transfer law

    International Nuclear Information System (INIS)

    Chen Lingen; Li Jun; Sun Fengrui

    2008-01-01

    The fundamental optimal relation between optimal power-output and efficiency of a generalized irreversible Carnot heat-engine is derived based on a generalized heat-transfer law, including a generalized convective heat-transfer law and a generalized radiative heat-transfer law, q ∝ (ΔT n ) m . The generalized irreversible Carnot-engine model incorporates several internal and external irreversibilities, such as heat resistance, bypass heat-leak, friction, turbulence and other undesirable irreversibility factors. The added irreversibilities, besides heat resistance, are characterized by a constant parameter and a constant coefficient. The effects of heat-transfer laws and various loss terms are analyzed. The results obtained corroborate those in the literature

  18. Absorption media for irreversibly gettering thionyl chloride

    Science.gov (United States)

    Buffleben, George; Goods, Steven H.; Shepodd, Timothy; Wheeler, David R.; Whinnery, Jr., LeRoy

    2002-01-01

    Thionyl chloride is a hazardous and reactive chemical used as the liquid cathode in commercial primary batteries. Contrary to previous thinking, ASZM-TEDA.RTM. carbon (Calgon Corporation) reversibly absorbs thionyl chloride. Thus, several candidate materials were examined as irreversible getters for thionyl chloride. The capacity, rate and effect of temperature were also explored. A wide variety of likely materials were investigated through screening experiments focusing on the degree of heat generated by the reaction as well as the material absorption capacity and irreversibility, in order to help narrow the group of possible getter choices. More thorough, quantitative measurements were performed on promising materials. The best performing getter was a mixture of ZnO and ASZM-TEDA.RTM. carbon. In this example, the ZnO reacts with thionyl chloride to form ZnCl.sub.2 and SO.sub.2. The SO.sub.2 is then irreversibly gettered by ASZM-TEDA.RTM. carbon. This combination of ZnO and carbon has a high capacity, is irreversible and functions effectively above -20.degree. C.

  19. The Value of Fighting Irreversible Demise by Softening the Irreversible Cost

    NARCIS (Netherlands)

    Magis, P.; Sbuelz, A.

    2005-01-01

    We study a novel issue in the real-options-based technology innovation literature by means of double barrier contingent claims analysis.We show how much a ¯rm with the monopoly over a project is willing to spend in investment technology innovation that softens the irreversible cost of accessing the

  20. Irreversible work in a thermal medium with colored noise

    International Nuclear Information System (INIS)

    Ohkuma, Takahiro

    2009-01-01

    Irreversible work and its fluctuations in a classical system governed by non-Markovian stochastic dynamics are investigated. The production of irreversible work depends not only on the protocol of an operation but also on the details of the non-Markovian memory. We consider a generalized Langevin equation with a memory kernel and derive an expression for the irreversible work in the case of slow operations by carrying out an expansion of this memory kernel in the parameter representing the length of the memory. We apply our formulation to a harmonically trapped system and demonstrate the efficiency of a cycle by evaluating the irreversible work. It is found that a decrease in the irreversible work due to the memory effect can occur for an operation through which the trap is squeezed. The results for this harmonic system are verified exactly in the case that the memory kernel has exponential decay

  1. Irreversible work in a thermal medium with colored noise

    Science.gov (United States)

    Ohkuma, Takahiro

    2009-10-01

    Irreversible work and its fluctuations in a classical system governed by non-Markovian stochastic dynamics are investigated. The production of irreversible work depends not only on the protocol of an operation but also on the details of the non-Markovian memory. We consider a generalized Langevin equation with a memory kernel and derive an expression for the irreversible work in the case of slow operations by carrying out an expansion of this memory kernel in the parameter representing the length of the memory. We apply our formulation to a harmonically trapped system and demonstrate the efficiency of a cycle by evaluating the irreversible work. It is found that a decrease in the irreversible work due to the memory effect can occur for an operation through which the trap is squeezed. The results for this harmonic system are verified exactly in the case that the memory kernel has exponential decay.

  2. Experimental and modelling study of the effect of airflow orientation with respect to strip electrode on ozone production of surface dielectric barrier discharge

    Science.gov (United States)

    Mikeš, J.; Pekárek, S.; Soukup, I.

    2016-11-01

    This study examines the effect of airflow orientation with respect to the strip active electrode on concentration of ozone and nitrogen dioxide produced in a planar generator based on the surface dielectric barrier discharge. The orientation of the airflow was tested in parallel and perpendicular with respect to the strips. It was found that in the investigated range of average discharge power, the ozone concentration increases approximately by 25% when airflow was oriented in parallel with respect to the strips in comparison with perpendicular orientation of the airflow. Similarly the increase of nitrogen dioxide concentration was observed for parallel orientation of the airflow with respect to the strips in comparison with the perpendicular orientation of the airflow. Within the range of wavelengths from 250 to 1100 nm, the changes of intensities of spectral lines associated with airflow orientation have been observed. A 3D numerical model describing ion trajectories and airflow patterns have also been developed.

  3. Exergetic efficiency optimization for an irreversible heat pump ...

    Indian Academy of Sciences (India)

    side ... For irreversible cycle, the internal irreversibility, i.e., non-isentropic losses in the ... constant thermal capacitance rate (the product of mass flow rate and specific heat), .... reversed Brayton cycle is dependent on the external heat transfer ...

  4. Pulmonary anatomy in the Nile crocodile and the evolution of unidirectional airflow in Archosauria

    Directory of Open Access Journals (Sweden)

    Emma R. Schachner

    2013-03-01

    Full Text Available The lungs of birds have long been known to move air in only one direction during both inspiration and expiration through most of the tubular gas-exchanging bronchi (parabronchi. Recently a similar pattern of airflow has been observed in American alligators, a sister taxon to birds. The pattern of flow appears to be due to the arrangement of the primary and secondary bronchi, which, via their branching angles, generate inspiratory and expiratory aerodynamic valves. Both the anatomical similarity of the avian and alligator lung and the similarity in the patterns of airflow raise the possibility that these features are plesiomorphic for Archosauria and therefore did not evolve in response to selection for flapping flight or an endothermic metabolism, as has been generally assumed. To further test the hypothesis that unidirectional airflow is ancestral for Archosauria, we measured airflow in the lungs of the Nile crocodile (Crocodylus niloticus. As in birds and alligators, air flows cranially to caudally in the cervical ventral bronchus, and caudally to cranially in the dorsobronchi in the lungs of Nile crocodiles. We also visualized the gross anatomy of the primary, secondary and tertiary pulmonary bronchi of C. niloticus using computed tomography (CT and microCT. The cervical ventral bronchus, cranial dorsobronchi and cranial medial bronchi display similar characteristics to their proposed homologues in the alligator, while there is considerable variation in the tertiary and caudal group bronchi. Our data indicate that the aspects of the crocodilian bronchial tree that maintain the aerodynamic valves and thus generate unidirectional airflow, are ancestral for Archosauria.

  5. The detection of local irreversibility in time series based on segmentation

    Science.gov (United States)

    Teng, Yue; Shang, Pengjian

    2018-06-01

    We propose a strategy for the detection of local irreversibility in stationary time series based on multiple scale. The detection is beneficial to evaluate the displacement of irreversibility toward local skewness. By means of this method, we can availably discuss the local irreversible fluctuations of time series as the scale changes. The method was applied to simulated nonlinear signals generated by the ARFIMA process and logistic map to show how the irreversibility functions react to the increasing of the multiple scale. The method was applied also to series of financial markets i.e., American, Chinese and European markets. The local irreversibility for different markets demonstrate distinct characteristics. Simulations and real data support the need of exploring local irreversibility.

  6. Childhood-onset asthma in smokers. association between CT measures of airway size, lung function, and chronic airflow obstruction.

    Science.gov (United States)

    Diaz, Alejandro A; Hardin, Megan E; Come, Carolyn E; San José Estépar, Raúl; Ross, James C; Kurugol, Sila; Okajima, Yuka; Han, MeiLan K; Kim, Victor; Ramsdell, Joe; Silverman, Edwin K; Crapo, James D; Lynch, David A; Make, Barry; Barr, R Graham; Hersh, Craig P; Washko, George R

    2014-11-01

    Asthma is associated with chronic airflow obstruction. Our goal was to assess the association of computed tomographic measures of airway wall volume and lumen volume with the FEV1 and chronic airflow obstruction in smokers with childhood-onset asthma. We analyzed clinical, lung function, and volumetric computed tomographic airway volume data from 7,266 smokers, including 590 with childhood-onset asthma. Small wall volume and small lumen volume of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small wall volume, small lumen volume, FEV1, and chronic airflow obstruction (post-bronchodilator FEV1/FVC ratio childhood-onset asthma, those with childhood-onset asthma had smaller wall volume and lumen volume (P childhood-onset asthma, those with the smallest wall volume and lumen volume had the lowest FEV1 and greatest odds of chronic airflow obstruction. A similar tendency was seen in those without childhood-onset asthma. When comparing these two groups, both small wall volume and small lumen volume were more strongly associated with FEV1 and chronic airflow obstruction among subjects with childhood-asthma in multivariate models. In smokers with childhood-onset asthma, smaller airways are associated with reduced lung function and chronic airflow obstruction. Clinical trial registered with www.clinicaltrials.gov (NCT00608764).

  7. Definition of airflow rate induced by polifractional materials

    Science.gov (United States)

    Popov, E. N.

    2018-03-01

    This paper deals with further analysis of a probabilistic and statistical approach to determine the aerodynamic drag coefficient of particles in a flow of free-falling polifractional material. It also describes the experimental assembly enabling one to determine airflow rate induced by polifractional material and provides comparison of analytical calculations with experimental data.

  8. Classification of Airflow Limitation Based on z-Score Underestimates Mortality in Patients with Chronic Obstructive Pulmonary Disease.

    Science.gov (United States)

    Tejero, Elena; Prats, Eva; Casitas, Raquel; Galera, Raúl; Pardo, Paloma; Gavilán, Adelaida; Martínez-Cerón, Elisabet; Cubillos-Zapata, Carolina; Del Peso, Luis; García-Río, Francisco

    2017-08-01

    Global Lung Function Initiative recommends reporting lung function measures as z-score, and a classification of airflow limitation (AL) based on this parameter has recently been proposed. To evaluate the prognostic capacity of the AL classifications based on z-score or percentage predicted of FEV 1 in patients with chronic obstructive pulmonary disease (COPD). A cohort of 2,614 patients with COPD recruited outside the hospital setting was examined after a mean (± SD) of 57 ± 13 months of follow-up, totaling 10,322 person-years. All-cause mortality was analyzed, evaluating the predictive capacity of several AL staging systems. Based on Global Initiative for Chronic Obstructive Lung Disease guidelines, 461 patients (17.6%) had mild, 1,452 (55.5%) moderate, 590 (22.6%) severe, and 111 (4.2%) very severe AL. According to z-score classification, 66.3% of patients remained with the same severity, whereas 23.7% worsened and 10.0% improved. Unlike other staging systems, patients with severe AL according to z-score had higher mortality than those with very severe AL (increase of risk by 5.2 and 3.9 times compared with mild AL, respectively). The predictive capacity for 5-year survival was slightly higher for FEV 1 expressed as percentage of predicted than as z-score (area under the curve: 0.714-0.760 vs. 0.649-0.708, respectively). A severity-dependent relationship between AL grades by z-score and mortality was only detected in patients younger than age 60 years. In patients with COPD, the AL classification based on z-score predicts worse mortality than those based on percentage of predicted. It is possible that the z-score underestimates AL severity in patients older than 60 years of age with severe functional impairment.

  9. Airflow Interaction Interface: Playful 3-D CAD and Gaming

    NARCIS (Netherlands)

    Wendrich, Robert E.

    2016-01-01

    This paper describes the vision and development of a tangible user interface (TUI) that allows ‘glassblowing-like’ interaction (IA) with a computer. The premise is that human fidelity in exerting pressure and airflow (i.e. breathing, blowing) could stimulate intuition, creative processing, and

  10. Fuel composition effect on cathode airflow control in fuel cell gas turbine hybrid systems

    Science.gov (United States)

    Zhou, Nana; Zaccaria, Valentina; Tucker, David

    2018-04-01

    Cathode airflow regulation is considered an effective means for thermal management in solid oxide fuel cell gas turbine (SOFC-GT) hybrid system. However, performance and controllability are observed to vary significantly with different fuel compositions. Because a complete system characterization with any possible fuel composition is not feasible, the need arises for robust controllers. The sufficiency of robust control is dictated by the effective change of operating state given the new composition used. It is possible that controller response could become unstable without a change in the gains from one state to the other. In this paper, cathode airflow transients are analyzed in a SOFC-GT system using syngas as fuel composition, comparing with previous work which used humidified hydrogen. Transfer functions are developed to map the relationship between the airflow bypass and several key variables. The impact of fuel composition on system control is quantified by evaluating the difference between gains and poles in transfer functions. Significant variations in the gains and the poles, more than 20% in most cases, are found in turbine rotational speed and cathode airflow. The results of this work provide a guideline for the development of future control strategies to face fuel composition changes.

  11. General thermodynamic performance of irreversible absorption heat pump

    International Nuclear Information System (INIS)

    Zhao Xiling; Fu Lin; Zhang Shigang

    2011-01-01

    The absorption heat pump (AHP) was studied with thermodynamics. A four reservoirs model of absorption heat pump was established considering the heat resistance, heat leak and the internal irreversibility. The reasonable working regions, the performance effects of irreversibility, heat leak and the correlation of four components were studied. When studying the effects of internal irreversibility, two internal irreversibility parameters (I he for generator-absorber assembly and I re for evaporator-condenser assembly) were introduced to distinguish the different effects. When studying the heat transfer relations of four components, a universal relationship between the main parameters were deduced. The results which have more realized meaning show that, the reduction of the friction, heat loss, and internal dissipations of the evaporator-condenser assembly are more important than its reduction of generator-absorber assembly, and lessening the heat leak of generator are more important than its reduction of other components to improve the AHP performance.

  12. Fine-scale flight strategies of gulls in urban airflows indicate risk and reward in city living.

    Science.gov (United States)

    Shepard, Emily L C; Williamson, Cara; Windsor, Shane P

    2016-09-26

    Birds modulate their flight paths in relation to regional and global airflows in order to reduce their travel costs. Birds should also respond to fine-scale airflows, although the incidence and value of this remains largely unknown. We resolved the three-dimensional trajectories of gulls flying along a built-up coastline, and used computational fluid dynamic models to examine how gulls reacted to airflows around buildings. Birds systematically altered their flight trajectories with wind conditions to exploit updraughts over features as small as a row of low-rise buildings. This provides the first evidence that human activities can change patterns of space-use in flying birds by altering the profitability of the airscape. At finer scales still, gulls varied their position to select a narrow range of updraught values, rather than exploiting the strongest updraughts available, and their precise positions were consistent with a strategy to increase their velocity control in gusty conditions. Ultimately, strategies such as these could help unmanned aerial vehicles negotiate complex airflows. Overall, airflows around fine-scale features have profound implications for flight control and energy use, and consideration of this could lead to a paradigm-shift in the way ecologists view the urban environment.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'. © 2016 The Author(s).

  13. Stochastic dynamics and irreversibility

    CERN Document Server

    Tomé, Tânia

    2015-01-01

    This textbook presents an exposition of stochastic dynamics and irreversibility. It comprises the principles of probability theory and the stochastic dynamics in continuous spaces, described by Langevin and Fokker-Planck equations, and in discrete spaces, described by Markov chains and master equations. Special concern is given to the study of irreversibility, both in systems that evolve to equilibrium and in nonequilibrium stationary states. Attention is also given to the study of models displaying phase transitions and critical phenomema both in thermodynamic equilibrium and out of equilibrium. These models include the linear Glauber model, the Glauber-Ising model, lattice models with absorbing states such as the contact process and those used in population dynamic and spreading of epidemic, probabilistic cellular automata, reaction-diffusion processes, random sequential adsorption and dynamic percolation. A stochastic approach to chemical reaction is also presented.The textbook is intended for students of ...

  14. Irreversible stochastic processes on lattices

    International Nuclear Information System (INIS)

    Nord, R.S.

    1986-01-01

    Models for irreversible random or cooperative filling of lattices are required to describe many processes in chemistry and physics. Since the filling is assumed to be irreversible, even the stationary, saturation state is not in equilibrium. The kinetics and statistics of these processes are described by recasting the master equations in infinite hierarchical form. Solutions can be obtained by implementing various techniques: refinements in these solution techniques are presented. Programs considered include random dimer, trimer, and tetramer filling of 2D lattices, random dimer filling of a cubic lattice, competitive filling of two or more species, and the effect of a random distribution of inactive sites on the filling. Also considered is monomer filling of a linear lattice with nearest neighbor cooperative effects and solve for the exact cluster-size distribution for cluster sizes up to the asymptotic regime. Additionally, a technique is developed to directly determine the asymptotic properties of the cluster size distribution. Finally cluster growth is considered via irreversible aggregation involving random walkers. In particular, explicit results are provided for the large-lattice-size asymptotic behavior of trapping probabilities and average walk lengths for a single walker on a lattice with multiple traps. Procedures for exact calculation of these quantities on finite lattices are also developed

  15. Irreversible thermodynamics of Poisson processes with reaction.

    Science.gov (United States)

    Méndez, V; Fort, J

    1999-11-01

    A kinetic model is derived to study the successive movements of particles, described by a Poisson process, as well as their generation. The irreversible thermodynamics of this system is also studied from the kinetic model. This makes it possible to evaluate the differences between thermodynamical quantities computed exactly and up to second-order. Such differences determine the range of validity of the second-order approximation to extended irreversible thermodynamics.

  16. Thermal performance of natural airflow window in subtropical and temperate climate zones - A comparative study

    International Nuclear Information System (INIS)

    Chow Tintai; Lin Zhang; Fong Kwongfai; Chan Lokshun; He Miaomiao

    2009-01-01

    Airflow window is highly useful in conserving building energy, and lessens the comfort problems caused by glazing. In this study, the thermal performance of a natural airflow window was examined through the use of a dynamic model, developed based on the integrated energy balance and airflow networks. The validity of the model was first tested by measured data obtained from a prototype installed at an environmental chamber. The application in the subtropical and temperate climate zones were then examined with the typical weather data of Hong Kong and Beijing. The findings confirmed that the natural airflow window can achieve substantial energy saving in both cities, and the reversible window frame is only required for Beijing, a location with hot summer and cold winter. The space cooling load via fenestration in Hong Kong, a subtropical city, can be reduced to 60% of the commonly used single absorptive glazing. In Beijing, as an example of the temperate climate, this can be reduced to 75% of the commonly used double glazing configuration in the summer period, and the space heat gain can be improved by 46% in the winter period.

  17. Room airflow studies using sonic anemometry.

    Science.gov (United States)

    Wasiolek, P T; Whicker, J J; Gong, H; Rodgers, J C

    1999-06-01

    To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s-1 to 9.7 cm s-1. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s-1 to 35.5 cm s-1 with turbulence intensities from 33% to 108%.

  18. Thermodynamic Analysis of an Irreversible Maisotsenko Reciprocating Brayton Cycle

    Directory of Open Access Journals (Sweden)

    Fuli Zhu

    2018-03-01

    Full Text Available An irreversible Maisotsenko reciprocating Brayton cycle (MRBC model is established using the finite time thermodynamic (FTT theory and taking the heat transfer loss (HTL, piston friction loss (PFL, and internal irreversible losses (IILs into consideration in this paper. A calculation flowchart of the power output (P and efficiency (η of the cycle is provided, and the effects of the mass flow rate (MFR of the injection of water to the cycle and some other design parameters on the performance of cycle are analyzed by detailed numerical examples. Furthermore, the superiority of irreversible MRBC is verified as the cycle and is compared with the traditional irreversible reciprocating Brayton cycle (RBC. The results can provide certain theoretical guiding significance for the optimal design of practical Maisotsenko reciprocating gas turbine plants.

  19. Transient Dynamics Simulation of Airflow in a CT-Scanned Human Airway Tree: More or Fewer Terminal Bronchi?

    Directory of Open Access Journals (Sweden)

    Shouliang Qi

    2017-01-01

    Full Text Available Using computational fluid dynamics (CFD method, the feasibility of simulating transient airflow in a CT-based airway tree with more than 100 outlets for a whole respiratory period is studied, and the influence of truncations of terminal bronchi on CFD characteristics is investigated. After an airway model with 122 outlets is extracted from CT images, the transient airflow is simulated. Spatial and temporal variations of flow velocity, wall pressure, and wall shear stress are presented; the flow pattern and lobar distribution of air are gotten as well. All results are compared with those of a truncated model with 22 outlets. It is found that the flow pattern shows lobar heterogeneity that the near-wall air in the trachea is inhaled into the upper lobe while the center flow enters the other lobes, and the lobar distribution of air is significantly correlated with the outlet area ratio. The truncation decreases airflow to right and left upper lobes and increases the deviation of airflow distributions between inspiration and expiration. Simulating the transient airflow in an airway tree model with 122 bronchi using CFD is feasible. The model with more terminal bronchi decreases the difference between the lobar distributions at inspiration and at expiration.

  20. EFFECTS OF TEMPERATURE AND AIRFLOW ON VOLUME DEVELOPMENT DURING BAKING AND ITS INFLUENCE ON QUALITY OF CAKE

    Directory of Open Access Journals (Sweden)

    NURUL ATIQAH SANI

    2014-06-01

    Full Text Available Volume and texture of cake are among the important parameters in measuring the quality of cake. The processing conditions play important roles in producing cakes of good quality. Recent studies focused more on the formulation and the manipulation of baking temperature, humidity and time instead of airflow condition. The objective of this study was to evaluate the effects of baking temperature and airflow on the volume development of cake and final cake quality such as volume development, firmness, springiness and moisture content. The cake was baked at three different temperatures (160oC, 170oC, and 180oC, and two different airflow conditions. Baking time, height changes of batter, texture and moisture content of cake were compared to identify the differences or similarities on the final product as the process conditions varied. Results showed that, airflow has more significant effects towards the product quality compared to baking temperature especially on baking time which was 25.58 - 45.16%, and the rate of height changes which was 0.7 mm/min. However, different baking temperatures had more significant effects towards volume expansion which was 2.86 – 8.37% and the springiness of cake which was 3.44% compared to airflow conditions.

  1. Antibiotic use for irreversible pulpitis.

    Science.gov (United States)

    Agnihotry, Anirudha; Fedorowicz, Zbys; van Zuuren, Esther J; Farman, Allan G; Al-Langawi, Jassim Hasan

    2016-02-17

    Irreversible pulpitis, which is characterised by acute and intense pain, is one of the most frequent reasons that patients attend for emergency dental care. Apart from removal of the tooth, the customary way of relieving the pain of irreversible pulpitis is by drilling into the tooth, removing the inflamed pulp (nerve) and cleaning the root canal. However, a significant number of dentists continue to prescribe antibiotics to stop the pain of irreversible pulpitis.This review updates the previous version published in 2013. To assess the effects of systemic antibiotics for irreversible pulpitis. We searched the Cochrane Oral Health Group's Trials Register (to 27 January 2016); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015, Issue 12); MEDLINE via Ovid (1946 to 27 January 2016); EMBASE via Ovid (1980 to 27 January 2016), ClinicalTrials.gov (to 27 January 2016) and the WHO International Clinical Trials Registry Platform (to 27 January 2016). There were no language restrictions in the searches of the electronic databases. Randomised controlled trials which compared pain relief with systemic antibiotics and analgesics, against placebo and analgesics in the acute preoperative phase of irreversible pulpitis. Two review authors screened studies and extracted data independently. We assessed the quality of the evidence of included studies using GRADEpro software. Pooling of data was not possible and a descriptive summary is presented. One trial assessed at low risk of bias, involving 40 participants was included in this update of the review. The quality of the body of evidence was rated low for the different outcomes. There was a close parallel distribution of the pain ratings in both the intervention and placebo groups over the seven-day study period. There was insufficient evidence to claim or refute a benefit for penicillin for pain intensity. There was no significant difference in the mean total number of ibuprofen tablets over the

  2. Chronic airflow obstruction after successful treatment of multidrug-resistant tuberculosis

    Directory of Open Access Journals (Sweden)

    Anthony L. Byrne

    2017-07-01

    Full Text Available Cross-sectional studies reveal an association between tuberculosis (TB and chronic airflow obstruction, but cannot adequately address confounding. We hypothesised that treated pulmonary TB is an independent risk factor for chronic airflow obstruction. The Pulmones Post TB cohort study enrolled participants from Lima, Peru, aged 10–70 years with a history of drug-susceptible (DS- or multidrug-resistant (MDR-TB who had completed treatment and were clinically cured. Unexposed participants without TB were randomly selected from the same districts. We assessed respiratory symptoms, relevant environmental exposures, and spirometric lung function pre- and post-bronchodilator. In total, 144 participants with DS-TB, 33 with MDR-TB and 161 unexposed participants were fully evaluated. Compared with unexposed participants, MDR-TB patients had lower lung volumes (adjusted mean difference in forced vital capacity −370 mL, 95% CI −644– −97 and post-bronchodilator airflow obstruction (adjusted OR 4.89, 95% CI 1.27–18.78. Participants who had recovered from DS-TB did not have lower lung volumes than unexposed participants, but were more likely to have a reduced forced expiratory volume in 1 s/forced vital capacity ratio <0.70 (adjusted OR 2.47, 95% CI 1.01–6.03. Individuals successfully treated for TB may experience long-lasting sequelae. Interventions facilitating earlier TB treatment and management of chronic respiratory disease should be explored.

  3. Advanced airflow distribution methods for reducing exposure of indoor pollution

    DEFF Research Database (Denmark)

    Cao, Guangyu; Nielsen, Peter Vilhelm; Melikov, Arsen

    2017-01-01

    The adverse effect of various indoor pollutants on occupants’ health have been recognized. In public spaces flu viruses may spread from person to person by airflow generated by various traditional ventilation methods, like natural ventilation and mixing ventilation (MV Personalized ventilation (PV......) supplies clean air close to the occupant and directly into the breathing zone. Studies show that it improves the inhaled air quality and reduces the risk of airborne cross-infection in comparison with total volume (TV) ventilation. However, it is still challenging for PV and other advanced air distribution...... methods to reduce the exposure to gaseous and particulate pollutants under disturbed conditions and to ensure thermal comfort at the same time. The objective of this study is to analyse the performance of different advanced airflow distribution methods for protection of occupants from exposure to indoor...

  4. Advanced airflow distribution methods for reducing exposure of indoor pollution

    DEFF Research Database (Denmark)

    Cao, Guangyu; Nielsen, Peter Vilhelm; Melikov, Arsen Krikor

    methods to reduce the exposure to gaseous and particulate pollutants under disturbed conditions and to ensure thermal comfort at the same time. The objective of this study is to analyse the performance of different advanced airflow distribution methods for protection of occupants from exposure to indoor......The adverse effect of various indoor pollutants on occupants’ health have been recognized. In public spaces flu viruses may spread from person to person by airflow generated by various traditional ventilation methods, like natural ventilation and mixing ventilation (MV Personalized ventilation (PV......) supplies clean air close to the occupant and directly into the breathing zone. Studies show that it improves the inhaled air quality and reduces the risk of airborne cross-infection in comparison with total volume (TV) ventilation. However, it is still challenging for PV and other advanced air distribution...

  5. Optimization of an irreversible Stirling regenerative cycle

    International Nuclear Information System (INIS)

    Aragón-González, G; Cano-Bianco, M; León-Galicia, A; Rivera-Camacho, J M

    2015-01-01

    In this work a Stirling regenerative cycle with some irreversibilities is analyzed. The analyzed irreversibilities are located at the heat exchangers. They receive a finite amount of heat and heat leakage occurs between both reservoirs. Using this model, power and the efficiency at maximum power are obtained. Some optimal design parameters for the exchanger heat areas and thermal conductances are presented. The relation between the power, efficiency and the results obtained are shown graphically

  6. FURTHER STUDIES ON THE VARIATION OF SPRAY DEPOSITS IN VINEYARDS WITH AIRFLOW RATE AND VOLUME RATE

    Directory of Open Access Journals (Sweden)

    Emanuele Cerruto

    2007-03-01

    Full Text Available The present research, continuing that reported in [2], deals with the spray application subject, so to investigate as volume rate and airflow rate, forward speed being equal, affect the foliar deposition in an espalier vineyard. Experimental trials were carried out by means of an air assisted towed sprayer, equipped with “Albuz ATR” nozzles. To take into account the influence of the development of the trees, the field trials were replicated in two phenological stages with an interval of about one month: “Inflorescences fully developed” (stage 1 and “Beginning of berry touch” (stage 2. A full factorial experiment was carried out for each growth stage, with two airflow rates (3.9 and 7.5 m3/s, three volume rates (103, 216, and 276 L/ha in the first growth stage and 154, 330 and 432 L/ha in the second growth stage, and four replicates, arranged according to a randomised complete block design. Working pressure (1.2 MPa and forward speed (1.4 m/s were kept unchanged for all the trials. The foliar deposition was measured by means of a spectrophotometric technique. The leaves were sampled on two depth layers and two or three heights, according to the trees’ development. The results showed that volume rate did not significantly influence the mean foliar deposition in both the two growth stages, while the highest deposits were obtained with the lowest airflow rate. The airflow rate × volume rate interaction, though not statistically significant, showed that low volume rates together with high airflow rates, result in a noticeable reduction in foliar deposition (29% with respect the grand mean, due to an increase of the spry drift, especially at the first growth stage, when the foliar development is little. These second tests, unlike those described in [2], did not show any positive influence of the airflow rate on the foliar deposition in the inner part of the canopy, so further investigations could be necessary to better understand the

  7. Reversible and irreversible heat engine and refrigerator cycles

    Science.gov (United States)

    Leff, Harvey S.

    2018-05-01

    Although no reversible thermodynamic cycles exist in nature, nearly all cycles covered in textbooks are reversible. This is a review, clarification, and extension of results and concepts for quasistatic, reversible and irreversible processes and cycles, intended primarily for teachers and students. Distinctions between the latter process types are explained, with emphasis on clockwise (CW) and counterclockwise (CCW) cycles. Specific examples of each are examined, including Carnot, Kelvin and Stirling cycles. For the Stirling cycle, potentially useful task-specific efficiency measures are proposed and illustrated. Whether a cycle behaves as a traditional refrigerator or heat engine can depend on whether it is reversible or irreversible. Reversible and irreversible-quasistatic CW cycles both satisfy Carnot's inequality for thermal efficiency, η ≤ η C a r n o t . Irreversible CCW cycles with two reservoirs satisfy the coefficient of performance inequality K ≤ K C a r n o t . However, an arbitrary reversible cycle satisfies K ≥ K C a r n o t when compared with a reversible Carnot cycle operating between its maximum and minimum temperatures, a potentially counterintuitive result.

  8. Effects of T-type Channel on Natural Convection Flows in Airflow-Path of Concrete Storage Cask

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Gyeong Uk; Kim, Hyoung Jin; Cho, Chun Hyung [KORAD, Daejeon (Korea, Republic of)

    2016-05-15

    The natural convection flows occurring in airflow-path are not simple due to complex flow-path configurations such as horizontal ducts, bent tube and annular flow-path. In addition, 16 T type channels acting as the shroud are attached vertically and 16 channel supporting the canister are attached horizontally on the inner surface of over-pack. The existence and nonexistence of T type channels have influences on the flow fields in airflow- path. The concrete storage cask has to satisfy the requirements to secure the thermal integrity under the normal, off-normal, and accident conditions. The present work is aiming at investigating the effects of T type channels on the flows in airflow-path under the normal conditions using the FLUENT 16.1 code. In order to focus on the flows in airflow-path, fuel regions in the canister are regarded as a single cylinder with heat sources and other components are fully modeled. This study investigated the flow fields in airflow-path of concrete storage cask, numerically. It was found that excepting for the fuel regions, maximum temperatures on other components were evaluated below allowable values. The location of maximum velocities depended on support channels, T type channels and flow area. The flows through air inlets developed along annular flow- path with forming the hot plumes. According to the existence and nonexistence of T type channel, the plume behavior showed the different flow patterns.

  9. Effects of hot airflow during spin-coating process on CH3NH3PbI3-xClx perovskite solar cells

    Science.gov (United States)

    Tanaka, Hiroki; Ohishi, Yuya; Oku, Takeo

    2018-01-01

    CH3NH3PbI3-xClx photovoltaic devices were fabricated, and the effects of hot airflow during spin-coating were investigated. Cubic perovskite crystals that is a high temperature phase were obtained by the hot airflow method. The conversion efficiencies of the devices prepared by the hot airflow were remained even after 56 days.

  10. Formation of Irreversible H-bonds in Cellulose Materials

    Science.gov (United States)

    Umesh P. Agarwal; Sally A. Ralph; Rick S. Reiner; Nicole M. Stark

    2015-01-01

    Understanding of formation of irreversible Hbonds in cellulose is important in a number of fields. For example, fields as diverse as pulp and paper and enzymatic saccharification of cellulose are affected. In the present investigation, the phenomenon of formation of irreversible H-bonds is studied in a variety of celluloses and under two different drying conditions....

  11. Resuspension of carbon dust collected in Tore Supra and exposed to turbulent airflow: Controlled experiments and comparison with model

    Energy Technology Data Exchange (ETDEWEB)

    Peillon, S., E-mail: samuel.peillon@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES/SCA/LPMA, Saclay, Gif-sur-Yvette 91192 (France); Roynette, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES/SCA/LPMA, Saclay, Gif-sur-Yvette 91192 (France); Grisolia, C. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Gensdarmes, F. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES/SCA/LPMA, Saclay, Gif-sur-Yvette 91192 (France)

    2014-11-15

    Highlights: • Mobilization of dust is a key issue for the safety assessment of fusion reactors. • Carbon dust has been collected on the plasma facing components of Tore Supra. • Samples exhibit bimodal particle size distributions. • Samples have been exposed to turbulent airflows for dust resuspension studies. • A comparison with the so-called Rock’n roll resuspension model is proposed. - Abstract: This work presents the results of experiments conducted with carbon microparticles collected in the tokamak Tore Supra in order to characterize their resuspension behaviour from a stainless-steel substrate when exposed to turbulent airflow. Experiments were conducted in a wind tunnel with controlled velocity profiles and monitored environmental conditions. A consequent amount of dust has been collected in the vessel of the tokamak and a bimodal particle size distribution of samples is first demonstrated. Comparison with resuspension of alumina powders with equivalent particle size distributions under turbulent airflow is also discussed. Results for both carbon and alumina microparticles are then compared to a theoretical resuspension model. Data reveal that exposing multilayer deposits with bimodal particle size distributions to low-speed flows (i.e. 3–10 m/s) induces a significant reduction of the mobilized fractions compared to what was predicted by the model. In addition, results helped to highlight some limitations in the model to physically describe changes in the adhesive strength that can occur with a polydisperse deposit.

  12. Simulation of Thermal Distribution and Airflow for Efficient Energy Consumption in a Small Data Centers

    Directory of Open Access Journals (Sweden)

    Jing Ni

    2017-04-01

    Full Text Available Data centers have become ubiquitous in the last few years in an attempt to keep pace with the processing and storage needs of the Internet and cloud computing. The steady growth in the heat densities of IT servers leads to a rise in the energy needed to cool them, and constitutes approximately 40% of the power consumed by data centers. However, many data centers feature redundant air conditioning systems that contribute to inefficient air distribution, which significantly increases energy consumption. This remains an insufficiently explored problem. In this paper, a typical, small data center with tiles for an air supply system with a raised floor is used. We use a fluent (Computational Fluid Dynamics, CFD to simulate thermal distribution and airflow, and investigate the optimal conditions of air distribution to save energy. The effects of the airflow outlet angle along the tile, the cooling temperature and the rate of airflow on the beta index as well as the energy utilization index are discussed, and the optimal conditions are obtained. The reasonable airflow distribution achieved using 3D CFD calculations and the parameter settings provided in this paper can help reduce the energy consumption of data centers by improving the efficiency of the air conditioning.

  13. Intrinsic irreversibility in quantum theory

    International Nuclear Information System (INIS)

    Prigogine, I.; Petrosky, T.Y.

    1987-01-01

    Quantum theory has a dual structure: while solutions of the Schroedinger equation evolve in a deterministic and time reversible way, measurement introduces irreversibility and stochasticity. This presents a contrast to Bohr-Sommerfeld-Einstein theory, in which transitions between quantum states are associated with spontaneous and induced transitions, defined in terms of stochastic processes. A new form of quantum theory is presented here, which contains an intrinsic form of irreversibility, independent of observation. This new form applies to situations corresponding to a continuous spectrum and to quantum states with finite life time. The usual non-commutative algebra associated to quantum theory is replaced by more general algebra, in which operators are also non-distributive. Our approach leads to a number of predictions, which hopefully may be verified or refuted in the next years. (orig.)

  14. Irreversibility and self-organization in spin glasses. 2. Irreversibility and the problem of configuration averaging

    International Nuclear Information System (INIS)

    Kovrov, V.P.; Kurbatov, A.M.

    1989-05-01

    The generalization of a configuration averaging to a system displaying irreversible effects is suggested. The properties of the ''pathological'' equilibrium state at low temperatures are determined and discussed. (author). 16 refs, 3 figs

  15. Room airflow studies using sonic anemometry

    International Nuclear Information System (INIS)

    Wasiolek, P.T.; Whicker, J.J.; Gong, H.; Rodgers, J.C.

    1999-01-01

    To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the-art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s -1 to 9.7 cm s -1 . There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s -1 to 35.5 cm s -1 with turbulence intensities from 33% to 108%. (au)

  16. Room airflow studies using sonic anemometry

    Energy Technology Data Exchange (ETDEWEB)

    Wasiolek, P.T.; Whicker, J.J.; Gong, H.; Rodgers, J.C. [Los Alamos National Lab., Health Physics Measurements Group, Los Alamos, NM (United States)

    1999-10-01

    To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the-art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s{sup -1} to 9.7 cm s{sup -1}. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s{sup -1} to 35.5 cm s{sup -1} with turbulence intensities from 33% to 108%. (au) 17 refs.

  17. Control of nasal vasculature and airflow resistance in the dog.

    Science.gov (United States)

    Lung, M A; Phipps, R J; Wang, J C; Widdicombe, J G

    1984-01-01

    Nasal vascular and airflow resistances have been measured in dogs, simultaneously on both sides separately. Vascular resistance was measured either by constant flow perfusion of the terminal branch of the maxillary artery (which supplies, via the sphenopalatine artery, the nasal septum, most of the turbinates and the nasal sinuses) or by measuring blood flow through this artery, maintained by the dog's own blood pressure. Airflow resistance was assessed by inserting balloon-tipped endotracheal catheters into the back of each nasal cavity via the nasopharynx, and measuring transnasal pressure at constant airflow through each side of the nose simultaneously. Preliminary experiments indicated that there was 5-10% collateral anastomosis between the two sides. Close-arterial injection of drugs showed different patterns of response. Adrenaline, phenylephrine, chlorpheniramine and low doses of prostaglandin F2 alpha increased vascular resistance and lowered airway resistance. Salbutamol, methacholine and histamine lowered vascular resistance and increased airway resistance. Dobutamine decreased airway resistance with a small increase in vascular resistance. Prostaglandins E1, E2 and F2 alpha (high dose) decreased both vascular and airway resistances. Substance P, eledoisin-related peptide and vasoactive intestinal polypeptide lowered vascular resistance with little change in airway resistance. The results are interpreted in terms of possible drug actions on precapillary resistance vessels, sinusoids and venules, and arteriovenous anastomoses. It is concluded that nasal airway resistance cannot be correlated with vascular resistance or blood flow, since the latter has a complex and ill-defined relationship with nasal vascular blood volume. PMID:6204040

  18. How Effective Is Supplemental Intraseptal Anesthesia in Patients with Symptomatic Irreversible Pulpitis?

    Science.gov (United States)

    Webster, Stephen; Drum, Melissa; Reader, Al; Fowler, Sara; Nusstein, John; Beck, Mike

    2016-10-01

    Previous studies have reported high levels of success with intraseptal injection for various dental procedures but provide limited information on the use of the injection during endodontic treatment. Therefore, the purpose of this prospective study was to determine the anesthetic efficacy of the supplemental intraseptal technique in mandibular posterior teeth diagnosed with symptomatic irreversible pulpitis when the conventional inferior alveolar nerve (IAN) block failed. One hundred patients with a diagnosis of symptomatic irreversible pulpitis in a mandibular posterior tooth were recruited. Following profound lip numbness after the administration of the conventional IAN block, endodontic treatment was initiated. Patients still experiencing moderate to severe pain during treatment were administered mesial and distal supplemental intraseptal injections using 0.7 mL 4% articaine with 1:000,000 epinephrine administered with a computer-controlled local anesthetic delivery unit. Success was defined as the ability to perform endodontic access and instrumentation with mild to no pain. Success with the IAN block was achieved in 25% of patients. Supplemental intraseptal injections provided success in 29% of patients. Supplemental intraseptal injections achieved profound pulpal anesthesia in 29% of patients when the IAN block failed. This low level of success would not provide predictable levels of anesthesia for patients requiring emergency endodontic treatment for symptomatic irreversible pulpitis in mandibular posterior teeth. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. Real-time monitoring for alpha emitters in high-airflow environments

    International Nuclear Information System (INIS)

    Koster, J.E.; MacArthur, D.W.; Bounds, J.A.; Rawool-Sullivan, M.; Whitley, C.R.; Conaway, J.G.; Steadman, P.A.

    1996-01-01

    Key problems in detecting alpha contamination for site characterization and decontamination and decommissioning that remain to be solved include measurement of airborne contamination, material holdup within pipes, and leakage of material containers. These problems are very difficult using traditional alpha detectors and systems. The ionization detection method (long-range alpha detection of LRAD) offers a number of specific advantages for these environmental measurements. An LRAD system detects the air molecules ionized by alpha-emitting contamination rather than the alpha particles. Thus, LRAD-based detectors are not limited by the short range of alpha particles and can be used to detect contamination anywhere that air can penetrate. Extending this technology to large enclosures of long pipes requires a system optimized for large airflows. In this paper we will present designs and preliminary results for high-volume flow-through air monitors based on the LRAD technique. In addition, we will discuss the behavior of the monitors and their potential applications

  20. Computational fluid dynamics (CFD) investigation of impacts of an obstruction on airflow in underground mines.

    Science.gov (United States)

    Zhou, L; Goodman, G; Martikainen, A

    2013-01-01

    Continuous airflow monitoring can improve the safety of the underground work force by ensuring the uninterrupted and controlled distribution of mine ventilation to all working areas. Air velocity measurements vary significantly and can change rapidly depending on the exact measurement location and, in particular, due to the presence of obstructions in the air stream. Air velocity must be measured at locations away from obstructions to avoid the vortices and eddies that can produce inaccurate readings. Further, an uninterrupted measurement path cannot always be guaranteed when using continuous airflow monitors due to the presence of nearby equipment, personnel, roof falls and rib rolls. Effective use of these devices requires selection of a minimum distance from an obstacle, such that an air velocity measurement can be made but not affected by the presence of that obstacle. This paper investigates the impacts of an obstruction on the behavior of downstream airflow using a numerical CFD model calibrated with experimental test results from underground testing. Factors including entry size, obstruction size and the inlet or incident velocity are examined for their effects on the distributions of airflow around an obstruction. A relationship is developed between the minimum measurement distance and the hydraulic diameters of the entry and the obstruction. A final analysis considers the impacts of continuous monitor location on the accuracy of velocity measurements and on the application of minimum measurement distance guidelines.

  1. Impact of acoustic airflow on intrasinus drug deposition: New insights into the vibrating mode and the optimal acoustic frequency to enhance the delivery of nebulized antibiotic.

    Science.gov (United States)

    Leclerc, Lara; Merhie, Amira El; Navarro, Laurent; Prévôt, Nathalie; Durand, Marc; Pourchez, Jérémie

    2015-10-15

    We investigated the impact of vibrating acoustic airflow, the high frequency (f≥100 Hz) and the low frequency (f≤45 Hz) sound waves, on the enhancement of intrasinus drug deposition. (81m)Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2-fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses, respectively. We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Sleep position and the ocular surface in a high airflow environment

    Directory of Open Access Journals (Sweden)

    Vinod Gauba, FRCOphth

    2014-01-01

    Full Text Available Purpose: To study the relationship between sleep position and ocular surface symptoms and signs in an high air flow environment. Methods: Prospective observational study of new patients attending the dry eye clinic was performed. Patients with pre-existing ocular history, relevant systemic history (e.g. Sjogren’s syndrome or who were using topical or systemic therapy for dry eye were not included. Data were collected from the patient to document their dry eye symptoms; preferred dependent sleeping side and their bedroom airflow. All patients were examined by a clinician blind to the patient’s responses where Schirmer’s test and slit lamp examination were performed looking for the presence of lagophthalmos and corneal epitheliopathy. Results: 48 patients enrolled into the study of which 23 were males and 25 were females with a normal and comparable age distribution. The study found a strong association between patients’ preferred sleeping side and the incidence of corneal epitheliopathy in the contralateral eye particularly in patients with evidence of lagophthalmos. Dry eye symptoms were found to be worse and tear production lower on the contralateral side to the preferred sleeping side particularly in patients who sleep in a high airflow environment. Conclusion: In patients sleeping in a high airflow environment with nocturnal lagophthalmos, this study observed an association between preferred dependent sleep position and increased dry eye symptoms, lower Schirmer’s scores and increased corneal epitheliopathy in the contralateral eye. Keywords: Sleep, Dry eyes, Lagophthalmos, Epiphora

  3. CFD modeling of airflow for indoor comfort in the tropics

    International Nuclear Information System (INIS)

    Aynsley, R.; Su, B.

    2006-01-01

    In humid tropical environments air movement is a common means to achieving indoor thermal comfort. In many locations closer to the equator, breezes are weaker and less reliable. Whatever the source of air movement it is important to quantity its potential in terms of the percentage of time the air movement will be available and the likely speed of the air movement in occupied zone of a building. It is also important to establish appropriate thermal comfort criteria with respect to air temperature, humidity and air movement. There are a number of techniques for modeling air movement inside naturally ventilated buildings. Boundary layer wind tunnels provide an opportunity to both measure and visually observe such airflow through model building. It is important to model adjacent buildings and any significant landscaping features that will influence outdoor airflow patterns. Such studies are relatively expensive. The recent availability of computational fluid dynamics (CFD) software for personal computers offers an alternative method for modeling air movement inside naturally ventilated buildings. Very expensive versions of this software have been available for large computers and work stations for many years but they have only recently become available for smaller computers. There are some features of such software that should be compared before purchasing a copy or a license. This paper discusses such features in detail. It is important in the case of natural ventilation that adjacent buildings and any significant landscaping features that will influence outdoor airflow patterns are included in the modeling. This paper also stresses the importance of calibrating the CFD software output against some physical measurements or wind tunnel modeling to ensure that the CFD results are realistic

  4. Determining the complex modulus of alginate irreversible hydrocolloid dental material.

    Science.gov (United States)

    King, Shalinie; See, Howard; Thomas, Graham; Swain, Michael

    2008-11-01

    The aim of the study is to investigate the visco-elastic response of an alginate irreversible hydrocolloid dental impression material during setting. A novel squeeze film Micro-Fourier Rheometer (MFR, GBC Scientific Equipment, Australia) was used to determine the complex modulus of an alginate irreversible hydrocolloid dental impression material (Algident, ISO 1563 Class A Type 1, Dentalfarm Australia Pty. Ltd.) during setting after mixing. Data was collected every 30s for 10 min in one study and every 10 min for a total of 60 min in another study. A high level of repeatability was observed. The results indicate that the MFR is capable of recording the complex shear modulus of alginate irreversible hydrocolloid for 60 min from the start of mixing and to simultaneously report the changing visco-elastic parameters at all frequencies between 1 Hz and 100 Hz. The storage modulus shows a dramatic increase to 370% of its starting value after 6 min and then reduces to 55% after 60 min. The loss modulus increases to a maximum of 175% of its starting value after 10 min and then reduces to 94% after 60 min. The MFR enables the changes in the complex modulus through the complete setting process to be followed. It is anticipated this approach may provide a better method to compare the visco-elastic properties of impression materials and assist with identification of optimum types for different clinical requirements. The high stiffness of the instrument and the use of band-limited pseudo-random noise as the input signal are the main advantages of this technique over conventional rheometers for determining the changes in alginate visco-elasticity.

  5. Numerical investigation on thermal performance and correlations of double skin facade with buoyancy-driven airflow

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, Alexandra; Zhai, Zhiqiang [Department of Civil, Environmental and Architectural Engineering, University of Colorado, UCB 428, ECOT 441, Boulder, CO 80309-0428 (United States)

    2008-07-01

    This paper briefly reviews the primary parameters for a double skin facade (DSF) design. The research presents an integrated and iterative modeling process for analyzing the thermal performance of DSF cavities with buoyancy-driven airflow by using a building energy simulation program (BESP) along with a computational fluid dynamics (CFD) package. A typical DSF cavity model has been established and simulated. The model and the modeling process have been calibrated and validated against the experimental data. The validated model was used to develop correlations that can be implemented in a BESP, allowing users to take advantage of the accuracy gained from CFD simulations without the required computation time. Correlations were developed for airflow rate through cavity, average and peak cavity air temperature, cavity air pressure, and interior convection coefficient. The correlations are valuable for 'back of the envelope' calculation and for examining accuracy of zonal-model-based energy and airflow simulation programs. (author)

  6. Substance P and CGRP expression in dental pulps with irreversible pulpitis.

    Science.gov (United States)

    Sattari, Mandana; Mozayeni, Mohammad Ali; Matloob, Arash; Mozayeni, Maryam; Javaheri, Homan H

    2010-08-01

    The purpose of this study was to compare substance P (SP) and calcitonin gene-related peptide (CGRP) expression in pulp tissue with clinically diagnosed symptomatic and asymptomatic irreversible pulpitis. Healthy pulps acted as controls. Five normal pulps and 40 with irreversible pulpitis (20 symptomatic and 20 asymptomatic) were obtained from 45 different patients. SP and CGRP expression was determined by competition binding assays using enzyme immunoassay. anova and Mann-Whitney tests were used to ascertain if there were statistically significant differences between the groups. The results showed that neuropeptides were found in all pulp samples. The highest and the lowest expressions for SP and CGRP were found in symptomatic irreversible pulpitis and healthy pulps groups, respectively. The differences between healthy pulps and the groups of pulps having irreversible pulpitis were significant (P pulpitis groups (P pulpitis groups were not significant. This study demonstrated that the expression of CGRP and SP is significantly higher in pulps with irreversible pulpitis compared with healthy pulps.

  7. Airflow in Tracheobronchial Tree of Subjects with Tracheal Bronchus Simulated Using CT Image Based Models and CFD Method.

    Science.gov (United States)

    Qi, Shouliang; Zhang, Baihua; Yue, Yong; Shen, Jing; Teng, Yueyang; Qian, Wei; Wu, Jianlin

    2018-03-01

    Tracheal Bronchus (TB) is a rare congenital anomaly characterized by the presence of an abnormal bronchus originating from the trachea or main bronchi and directed toward the upper lobe. The airflow pattern in tracheobronchial trees of TB subjects is critical, but has not been systemically studied. This study proposes to simulate the airflow using CT image based models and the computational fluid dynamics (CFD) method. Six TB subjects and three health controls (HC) are included. After the geometric model of tracheobronchial tree is extracted from CT images, the spatial distribution of velocity, wall pressure, wall shear stress (WSS) is obtained through CFD simulation, and the lobar distribution of air, flow pattern and global pressure drop are investigated. Compared with HC subjects, the main bronchus angle of TB subjects and the variation of volume are large, while the cross-sectional growth rate is small. High airflow velocity, wall pressure, and WSS are observed locally at the tracheal bronchus, but the global patterns of these measures are still similar to those of HC. The ratio of airflow into the tracheal bronchus accounts for 6.6-15.6% of the inhaled airflow, decreasing the ratio to the right upper lobe from 15.7-21.4% (HC) to 4.9-13.6%. The air into tracheal bronchus originates from the right dorsal near-wall region of the trachea. Tracheal bronchus does not change the global pressure drop which is dependent on multiple variables. Though the tracheobronchial trees of TB subjects present individualized features, several commonalities on the structural and airflow characteristics can be revealed. The observed local alternations might provide new insight into the reason of recurrent local infections, cough and acute respiratory distress related to TB.

  8. Voluntary Cough Airflow Differentiates Safe versus Unsafe Swallowing in Amyotrophic Lateral Sclerosis

    Science.gov (United States)

    Plowman, Emily K.; Watts, Stephanie A.; Robison, Raele; Tabor, Lauren; Dion, Charles; Gaziano, Joy; Vu, Tuan; Gooch, Clifton

    2016-01-01

    Dysphagia and aspiration are prevalent in amyotrophic lateral sclerosis (ALS) and contribute to malnutrition, aspiration pneumonia and death. Early detection of at risk individuals is critical to ensure maintenance of safe oral intake and optimal pulmonary function. We therefore aimed to determine the discriminant ability of voluntary cough airflow measures in detecting penetration/aspiration status in ALS patients. Seventy individuals with ALS (El-Escorial criteria) completed voluntary cough spirometry testing and underwent a standardized videofluoroscopic swallowing evaluation (VFSE). A rater blinded to aspiration status derived six objective measures of voluntary cough airflow and evaluated airway safety using the Penetration Aspiration Scale (PAS). A between groups ANOVA (safe vs. unsafe swallowers) was conducted and sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated. VFSE analysis revealed 24 penetrator/aspirators (PAS ≥3) and 46 non-penetrator/aspirators (PAS ≤2). Cough volume acceleration (CVA), peak expiratory flow rise time (PEFRT), and peak expiratory flow rate (PEFR) were significantly different between airway safety groups (p 76ms had sensitivities of 91.3%, 82.6% and 73.9% respectively and specificities of 82.2%, 73.9%, and 78.3% for identifying ALS penetrator/aspirators. Voluntary cough airflow measures identified ALS patients at risk for penetration/aspiration and may be a valuable screening tool with high clinical utility. PMID:26803772

  9. Trends in pharmacotherapy for chronic airflow limitation in Argentina: 1992-2002 Tendencias en el tratamiento farmacológico de la obstrucción crónica al flujo aéreo en Argentina: 1992-2002

    Directory of Open Access Journals (Sweden)

    Néstor A. Molfino

    2004-10-01

    Full Text Available Asthma and COPD mortality rates have decreased in Argentina. These trends might be the result of the way these conditions are being treated. The number of units for prescription and over-the-counter (OTC drugs used to treat chronic airflow limitation in Argentina from 1992 through 2002 were analyzed. Units for drugs to treat chronic airflow limitation fell by 45% over the 11-year period (p Las tasas de mortalidad por asma y enfermedad pulmonar obstructiva crónica (EPOC se han reducido en Argentina. Estas tendencias pueden deberse a la forma en que tales enfermedades son tratadas. Se analizaron los medicamentos utilizados para el tratamiento del asma y EPOC desde 1992 hasta el año 2002. El total de unidades utilizadas cayó un 45% (p = 0.0001 debido a una reducción significativa de los agonistas orales b2 (83%, las teofilinas (74% los esteroides orales (66% y los agonistas inhalados b2 de acción corta (28%. La fracción de mercado de los esteroides inhalados aumentó del 2.6% al 11.7%, en el caso de ipratropio del 0.35% al 3.7%, la combinación de esteroides inhalados y agonistas b2 de acción corta aumentaron del 7.8% al 13% y la combinación de ipratropio con agonistas inhalados b2 de acción corta aumentó del 1.7% al 7.3%. Los agonistas inhalados b2 de acción prolongada y los antileukotrienos fueron recetados raramente en el período analizado. El uso de terapias más específicas (esteroides inhalados e ipratropio aumentó significativamente de acuerdo con las recomendaciones para el tratamiento del asma y EPOC y esto podría explicar las reducciones en las tasas de mortalidad de estas enfermedades.

  10. Guinea pig ductus arteriosus. II - Irreversible closure after birth.

    Science.gov (United States)

    Fay, F. S.; Cooke, P. H.

    1972-01-01

    To investigate the mechanism underlying irreversibility of ductal closure after birth, studies were undertaken to determine the exact time course for the onset of irreversible closure of the guinea pig ductus arteriosus. Parallel studies of the reactivity of ductal smooth muscle to oxygen and studies of the postpartum cellular changes within the vessel were also carried out.

  11. Multiscale time irreversibility of heart rate and blood pressure variability during orthostasis

    International Nuclear Information System (INIS)

    Chladekova, L; Czippelova, B; Turianikova, Z; Tonhajzerova, I; Calkovska, A; Javorka, M; Baumert, M

    2012-01-01

    Time irreversibility is a characteristic feature of non-equilibrium, complex systems such as the cardiovascular control mediated by the autonomic nervous system (ANS). Time irreversibility analysis of heart rate variability (HRV) and blood pressure variability (BPV) represents a new approach to assess cardiovascular regulatory mechanisms. The aim of this paper was to assess the changes in HRV and BPV irreversibility during the active orthostatic test (a balance of ANS shifted towards sympathetic predominance) in 28 healthy young subjects. We used three different time irreversibility indices—Porta’s, Guzik's and Ehler's indices (P%, G% and E, respectively) derived from data segments containing 1000 beat-to-beat intervals on four timescales. We observed an increase in the HRV and a decrease in the BPV irreversibility during standing compared to the supine position. The postural change in irreversibility was confirmed by surrogate data analysis. The differences were more evident in G% and E than P% and for higher scale factors. Statistical analysis showed a close relationship between G% and E. Contrary to this, the association between P% and G% and P% and E was not proven. We conclude that time irreversibility of beat-to-beat HRV and BPV is significantly altered during orthostasis, implicating involvement of the autonomous nervous system in its generation. (paper)

  12. Irreversibility and conditional probability

    International Nuclear Information System (INIS)

    Stuart, C.I.J.M.

    1989-01-01

    The mathematical entropy - unlike physical entropy - is simply a measure of uniformity for probability distributions in general. So understood, conditional entropies have the same logical structure as conditional probabilities. If, as is sometimes supposed, conditional probabilities are time-reversible, then so are conditional entropies and, paradoxically, both then share this symmetry with physical equations of motion. The paradox is, of course that probabilities yield a direction to time both in statistical mechanics and quantum mechanics, while the equations of motion do not. The supposed time-reversibility of both conditionals seems also to involve a form of retrocausality that is related to, but possibly not the same as, that described by Costa de Beaurgard. The retrocausality is paradoxically at odds with the generally presumed irreversibility of the quantum mechanical measurement process. Further paradox emerges if the supposed time-reversibility of the conditionals is linked with the idea that the thermodynamic entropy is the same thing as 'missing information' since this confounds the thermodynamic and mathematical entropies. However, it is shown that irreversibility is a formal consequence of conditional entropies and, hence, of conditional probabilities also. 8 refs. (Author)

  13. Experimental investigation into the interaction between the human body and room airflow and its effect on thermal comfort under stratum ventilation.

    Science.gov (United States)

    Cheng, Y; Lin, Z

    2016-04-01

    Room occupants' comfort and health are affected by the airflow. Nevertheless, they themselves also play an important role in indoor air distribution. This study investigated the interaction between the human body and room airflow under stratum ventilation. Simplified thermal manikin was employed to effectively resemble the human body as a flow obstacle and/or free convective heat source. Unheated and heated manikins were designed to fully evaluate the impact of the manikin at various airflow rates. Additionally, subjective human tests were conducted to evaluate thermal comfort for the occupants in two rows. The findings show that the manikin formed a local blockage effect, but the supply airflow could flow over it. With the body heat from the manikin, the air jet penetrated farther compared with that for the unheated manikin. The temperature downstream of the manikin was also higher because of the convective effect. Elevating the supply airflow rate from 7 to 15 air changes per hour varied the downstream airflow pattern dramatically, from an uprising flow induced by body heat to a jet-dominated flow. Subjective assessments indicated that stratum ventilation provided thermal comfort for the occupants in both rows. Therefore, stratum ventilation could be applied in rooms with occupants in multiple rows. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Simulation of whole building coupled hygrothermal-airflow transfer in different climates

    International Nuclear Information System (INIS)

    Qin Menghao; Walton, George; Belarbi, Rafik; Allard, Francis

    2011-01-01

    The coupled heat, air and moisture transfer between building envelopes and indoor air is complicated, and has a significant influence on the indoor environment and the energy performance of buildings. In the paper, a model for predicting coupled multi-zone hygrothermal-airflow transfer is presented. Both heat and moisture transfer in the building envelope and multi-zone indoor airflow are simultaneously considered; their interactions are modeled. The coupled system model is implemented into Matlab-Simulink, and is validated by using a series of testing tools and experiments. The new program is applied to investigate the moisture transfer effect on indoor air humidity and building energy consumption in different climates (hot-humid, temperate and hot-dry climates). The results show that not accounting for hygrothermal effects in modeling will result in overestimation of energy costs for hot and humid climate situations and possible over sizing of plant leading to inefficient operation.

  15. Influence of airflow rate and substrate nature on heterogeneous struvite precipitation.

    Science.gov (United States)

    Saidou, H; Ben Moussa, S; Ben Amor, M

    2009-01-01

    In wastewater treatment plants a hard scale consisting of struvite crystals can be formed, in pipes and recirculation pumps, during anaerobic digestion of wastewater. This study was conducted to evaluate the effect of airflow rate and substrate nature on nucleation type, induction period and supersaturation coefficient during struvite precipitation. A crystallization reactor similar to that designed for calcium carbonate precipitation was used. The pH of synthetic wastewater solution was increased by air bubbling. Experimental results indicated that the airflow increased heterogeneous precipitation of struvite. The susceptibility to scale formation was more important on polyamide and polyvinyl chloride than on stainless steel. In all cases, X-ray diffraction and infrared spectroscopy showed that the precipitated solid phase was solely struvite. No difference in crystal morphology was observed. However, at similar experimental conditions, the particle size of struvite was higher for stainless-steel material than that for plastic materials.

  16. Performance Optimization of Irreversible Air Heat Pumps Considering Size Effect

    Science.gov (United States)

    Bi, Yuehong; Chen, Lingen; Ding, Zemin; Sun, Fengrui

    2018-06-01

    Considering the size of an irreversible air heat pump (AHP), heating load density (HLD) is taken as thermodynamic optimization objective by using finite-time thermodynamics. Based on an irreversible AHP with infinite reservoir thermal-capacitance rate model, the expression of HLD of AHP is put forward. The HLD optimization processes are studied analytically and numerically, which consist of two aspects: (1) to choose pressure ratio; (2) to distribute heat-exchanger inventory. Heat reservoir temperatures, heat transfer performance of heat exchangers as well as irreversibility during compression and expansion processes are important factors influencing on the performance of an irreversible AHP, which are characterized with temperature ratio, heat exchanger inventory as well as isentropic efficiencies, respectively. Those impacts of parameters on the maximum HLD are thoroughly studied. The research results show that HLD optimization can make the size of the AHP system smaller and improve the compactness of system.

  17. Kinetic theory of nonequilibrium ensembles, irreversible thermodynamics, and generalized hydrodynamics

    CERN Document Server

    Eu, Byung Chan

    2016-01-01

    This book presents the fundamentals of irreversible thermodynamics for nonlinear transport processes in gases and liquids, as well as for generalized hydrodynamics extending the classical hydrodynamics of Navier, Stokes, Fourier, and Fick. Together with its companion volume on relativistic theories, it provides a comprehensive picture of the kinetic theory formulated from the viewpoint of nonequilibrium ensembles in both nonrelativistic and, in Vol. 2, relativistic contexts. Theories of macroscopic irreversible processes must strictly conform to the thermodynamic laws at every step and in all approximations that enter their derivation from the mechanical principles. Upholding this as the inviolable tenet, the author develops theories of irreversible transport processes in fluids (gases or liquids) on the basis of irreversible kinetic equations satisfying the H theorem. They apply regardless of whether the processes are near to or far removed from equilibrium, or whether they are linear or nonlinear with respe...

  18. How to account for irreversibility in integrated assessment of climate change?; Comment tenir compte de l'irreversibilite dans l'evaluation integree du changement climatique?

    Energy Technology Data Exchange (ETDEWEB)

    Ha Duong, M

    1998-04-15

    How to account for irreversibility in integrated assessment of climate change? This Ph. D. thesis in Economics balances discounting, technical progress and the inertia of existing capital stock against uncertainty and the inertia of socio-economic systems to examine the issue of near term limitations of greenhouse gases emissions. After a general overview in chapter 2, and a more historical presentation of the debates in chapter 3, chapter 4 proceeds to review a large number of integrated assessment models. Chapter 5 introduces a Model on the Dynamics of Inertia and Adaptability of energy systems: DIAM, used to discuss how much previous studies might have overestimated the long term costs of CO{sub 2} limitations and underestimated adjustment costs. It shows that, given a target date for atmospheric CO{sub 2} concentration stabilisation, a higher inertia implies a lower optimal concentration trajectory. In a sequential decision framework, chapter 6 shows that current uncertainties about which CO{sub 2} concentration ceiling would not present dangerous interference with the climate system justifies precautionary action. Finally, chapter 7 uses the irreversibility effect theory to define formally situations of decision under controversy and compare the irreversibility of CO{sub 2} accumulation with the irreversibility of investments needed to moderate it. An option value for greenhouse gases emissions limitations is computed. (author)

  19. Airflow and Contaminant Distribution in Hospital Wards with a Displacement Ventililation System

    DEFF Research Database (Denmark)

    Qian, H.; Nielsen, Peter Vilhelm; Li, Y.

    2004-01-01

    Airflow and Contaminant Distribution in Hospital Wards with a Displacement Ventilalation System. The 2nd International Conference on Build Environment and Public Health, BEPH 2004, Shenzhen , China . ABSTRACT Displacement ventilation has not been considered to be an applicable system for hospital...... to accurately predict three-dimensional distribution of air velocity, temperature, and contaminant concentration in the ward. Indoor airflow in a displacement ventilation system involves a combination of different flow streams such as the gravity currents and thermal plumes. It is important to choose...... ventilation system in hospital wards. It is for this purpose that we study the performance of displacement ventilation in hospital wards as one of the steps to optimize the ventilation design. When the prospect of applying displacement ventilation system in a hospital ward is examined, it should be necessary...

  20. The effects of pen partitions and thermal pig simulators on airflow in a livestock test room

    DEFF Research Database (Denmark)

    Bjerg, B.; Svidt, Kjeld; Zhang, G.

    2000-01-01

    measurements and CFD simulations showed that the introduction of pen partitions and thermal pig simulators reduced the air velocities in the occupied zone of the test room. Detailed geometric modelling of the animals might often be unnecessary for simulation of airflow in livestock rooms. This will especially......The aim of this work was to investigate the influence of pen partitions and heated simulated pigs on airflow in a slot ventilated test room and to evaluate computer fluid dynamics (CFD) as a tool to predict airflow in livestock rooms. To obtain two-dimensional flow in the occupied zone, four...... guiding plates were mounted beneath the ceiling in the test room. Experiments were carried out in three arrangements: (a) the room with guiding plates; (b) the room with guiding plates and eight heated pig simulators; and (c) the room with guiding plates, eight heated pig simulators and 0.8 m high...

  1. Spectral line intensity irreversibility in circulatory plasma magnetization processes

    Science.gov (United States)

    Qu, Z. Q.; Dun, G. T.

    2012-01-01

    Spectral line intensity variation is found to be irreversible in circulatory plasma magnetization process by experiments described in this paper, i.e., the curves illustrating spectral line photon fluxes irradiated from a light source immerged in a magnetic field by increasing the magnetic induction cannot be reproduced by decreasing the magnetic induction within the errors. There are two plasma magnetization patterns found. One shows that the intensities are greater at the same magnetic inductions during the magnetic induction decreasing process after the increasing, and the other gives the opposite effect. This reveals that the magneto-induced excitation and de-excitation process is irreversible like ferromagnetic magnetization. But the two irreversible processes are very different in many aspects stated in the text.

  2. Differentiating between adductor and abductor spasmodic dysphonia using airflow interruption

    Science.gov (United States)

    Hoffman, Matthew R.; Jiang, Jack J.; Rieves, Adam L.; McElveen, Kelsey A.B.; Ford, Charles N.

    2009-01-01

    Objective To measure the laryngeal resistance (RL), subglottal pressure (Ps), and mean flow rate (MFR) of adductor (ADSD) and abductor (ABSD) spasmodic dysphonia patients using the airflow interrupter. Methods The RL of six ABSD and seven ADSD patients was measured using the airflow interrupter, a noninvasive device designed to measure MFR and Ps via mechanical balloon valve interruption. Subjects performed ten trials at each of two intensity levels, with each trial consisting of a sustained /a/ during which phonation was interrupted for 500 ms. Laryngeal resistance was calculated as subglottal pressure divided by airflow. Results Mean RL for the ADSD and ABSD subtypes at 65 dB were 24.78 cmH2O/l/s and 14.51 cmH2O/l/s, respectively (p = 0.04). Mean RL at 70 dB were 40.02 cmH2O/l/s and 15.84 cmH2O/l/s (p = 0.014). Ps for the ADSD and ABSD subtypes at 65 dB were 10.23 cmH2O and 8.32 cmH2O, respectively (p = 0.582). At the 70 dB level, Ps were 12.39 cmH2O and 11.78 cmH2O (p = 0.886). MFR for the ADSD and ABSD subtypes at 65 dB were 435 ml/s and 746 ml/s (p = 0.205). Mean MFR at 70 dB were 518 ml/s and 848 ml/s (p = 0.198). Conclusion Noninvasive measurements of RL may be useful for differentiating between ADSD and ABSD. This simple objective test which produces a quantitative output could be used to evaluate laryngeal function in patients with spasmodic dysphonia. PMID:19554636

  3. Ecological optimization and parametric study of irreversible Stirling and Ericsson heat pumps

    International Nuclear Information System (INIS)

    Tyagi, S.K.; Kaushik, S.C.; Salohtra, R.

    2002-01-01

    This communication presents the ecological optimization and parametric study of irreversible Stirling and Ericsson heat pump cycles, in which the external irreversibility is due to finite temperature difference between working fluid and external reservoirs while the internal irreversibilities are due to regenerative heat loss and other entropy generations within the cycle. The ecological function is defined as the heating load minus the irreversibility (power loss) which is ambient temperature times the entropy generation. The ecological function is optimized with respect to working fluid temperatures, and the expressions for various parameters at the optimal operating condition are obtained. The effects of different operating parameters on the performance of these cycles have been studied. It is found that the effect of internal irreversibility parameter is more pronounced than the other parameters on the performance of these cycles. (author)

  4. Morphological measurements in computed tomography correlate with airflow obstruction in chronic obstructive pulmonary disease: systematic review and meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Xie, XueQian; Oudkerk, Matthijs; Vliegenthart, Rozemarijn [University of Groningen, University Medical Center Groningen, Center for Medical Imaging-North East Netherlands (CMI-NEN), Department of Radiology, Hanzeplein 1, P.O. Box 30.001, RB, Groningen (Netherlands); Jong, Pim A. de [University Medical Center Utrecht, University of Utrecht, Department of Radiology, Heidelberglaan 100, P.O. Box 85.500, CX, Utrecht (Netherlands); Wang, Ying [Tianjin Medical University General Hospital, Department of Radiology, Tianjin (China); Hacken, Nick H.T. ten [University of Groningen, University Medical Center Groningen, Department of Pulmonary Diseases, Hanzeplein 1, P.O. Box 30.001, RB, Groningen (Netherlands); Miao, Jingtao; Zhang, GuiXiang [Shanghai Jiao Tong University Affiliated First People' s Hospital, Department of Radiology, Shanghai (China); Bock, Geertruida H. de [University of Groningen, University Medical Center Groningen, Department of Epidemiology, Hanzeplein 1, P.O. Box 30.001, RB, Groningen (Netherlands)

    2012-10-15

    To determine the correlation between CT measurements of emphysema or peripheral airways and airflow obstruction in chronic obstructive pulmonary disease (COPD). PubMed, Embase and Web of Knowledge were searched from 1976 to 2011. Two reviewers independently screened 1,763 citations to identify articles that correlated CT measurements to airflow obstruction parameters of the pulmonary function test in COPD patients, rated study quality and extracted information. Three CT measurements were accessed: lung attenuation area percentage < -950 Hounsfield units, mean lung density and airway wall area percentage. Two airflow obstruction parameters were accessed: forced expiratory volume in the first second as percentage from predicted (FEV{sub 1} %pred) and FEV{sub 1} divided by the forced volume vital capacity. Seventy-nine articles (9,559 participants) were included in the systematic review, demonstrating different methodologies, measurements and CT airflow obstruction correlations. There were 15 high-quality articles (2,095 participants) in the meta-analysis. The absolute pooled correlation coefficients ranged from 0.48 (95 % CI, 0.40 to 0.54) to 0.65 (0.58 to 0.71) for inspiratory CT and 0.64 (0.53 to 0.72) to 0.73 (0.63 to 0.80) for expiratory CT. CT measurements of emphysema or peripheral airways are significantly related to airflow obstruction in COPD patients. CT provides a morphological method to investigate airway obstruction in COPD. (orig.)

  5. Ictal time-irreversible intracranial EEG signals as markers of the epileptogenic zone.

    Science.gov (United States)

    Schindler, Kaspar; Rummel, Christian; Andrzejak, Ralph G; Goodfellow, Marc; Zubler, Frédéric; Abela, Eugenio; Wiest, Roland; Pollo, Claudio; Steimer, Andreas; Gast, Heidemarie

    2016-09-01

    To show that time-irreversible EEG signals recorded with intracranial electrodes during seizures can serve as markers of the epileptogenic zone. We use the recently developed method of mapping time series into directed horizontal graphs (dHVG). Each node of the dHVG represents a time point in the original intracranial EEG (iEEG) signal. Statistically significant differences between the distributions of the nodes' number of input and output connections are used to detect time-irreversible iEEG signals. In 31 of 32 seizure recordings we found time-irreversible iEEG signals. The maximally time-irreversible signals always occurred during seizures, with highest probability in the middle of the first seizure half. These signals spanned a large range of frequencies and amplitudes but were all characterized by saw-tooth like shaped components. Brain regions removed from patients who became post-surgically seizure-free generated significantly larger time-irreversibilities than regions removed from patients who still had seizures after surgery. Our results corroborate that ictal time-irreversible iEEG signals can indeed serve as markers of the epileptogenic zone and can be efficiently detected and quantified in a time-resolved manner by dHVG based methods. Ictal time-irreversible EEG signals can help to improve pre-surgical evaluation in patients suffering from pharmaco-resistant epilepsies. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  6. Irreversible properties of YBCO coated conductors

    International Nuclear Information System (INIS)

    Vostner, A.

    2001-02-01

    Over the past few years substantial efforts were made to optimize the fabrication techniques of various high temperature superconductors for commercial applications. In addition to Bi-2223 tapes, Y-123 coated conductors have the potential for large-scale production and are considered as the second generation of superconducting 'wires' for high current applications. This work reports on magnetic and transport current investigations of Y-123 thick films deposited on either single crystalline substrates by liquid phase epitaxy (LPE) or on metallic substrates by pulsed laser deposition (PLD). At the beginning, a short introduction of the general idea of a coated conductor and of the different production techniques is presented, followed by a description of the different experimental set-ups and the evaluation methods. The main part starts with the results obtained from SQUID magnetometry and ac-susceptibility measurements including the transition temperatures T c , the field dependence of the magnetic critical current densities and the irreversibility lines. In addition, some issues concerning the granular structure and the inter- and intragranular current distribution of the superconducting films are discussed. The investigations by transport currents are focused on the behavior of the application relevant irreversible parameters. These are the angular and the field dependence of the critical transport current densities at 77 and 60 K, as well as the temperature dependence of the irreversibility fields up to 6 T. To gain more insight into the defect structure of the films, neutron irradiation studies were performed on some samples. The introduction of these artificial pinning centers causes large enhancements of the magnetic J c in LPE specimens for the field parallel to the c-axis (H//c) at higher temperatures and magnetic fields. The granular structure of the samples does not change up to the highest neutron fluences. However, the enhancements of the transport J c

  7. Irreversibility analysis in the process of solar distillation

    International Nuclear Information System (INIS)

    Chávez, S; Terres, H; Lizardi, A; López, R; Lara, A

    2017-01-01

    In this work an irreversibility analysis for the thermal process of solar distillation of three different substances is presented, for which it employs a solar still of a slope where three experimental tests with 5.5 L of brine, river water and MgCl 2 were performed. Temperature data principally in the glass cover, absorber plate, fluid, environment and the incident solar radiation on the device were obtained. With measurements of temperature, solar radiation and exergetic balance, irreversibilities are found on the device. The results show that the highest values of irreversibilities are concentrated in the absorber plate with an average of 321 W, 342 W and 276 W, followed by the cover glass with an average of 75.8 W, 80.4 W and 86.7 W and finally the fluid with 15.3 W, 15.9 W and 16 W, for 5.5 L of brine, river water and MgCl 2 . (paper)

  8. Testing measurements of airflow velocity in road tunnels

    Directory of Open Access Journals (Sweden)

    Danišovič Peter

    2017-01-01

    Full Text Available Within the project entitled “Models of formation and spread of fire to increase safety of road tunnels”, it was necessary to devise a method how to record airflow velocity during the fire in situ tests in road tunnels. Project is in first year of its solution so one testing measurement was performed to check the functionality of anemometers selected for this project and the first in situ measurement was also performed just a few days ago.

  9. Magnetic resonance imaging and computational fluid dynamics (CFD) simulations of rabbit nasal airflows for the development of hybrid CFD/PBPK models.

    Science.gov (United States)

    Corley, R A; Minard, K R; Kabilan, S; Einstein, D R; Kuprat, A P; Harkema, J R; Kimbell, J S; Gargas, M L; Kinzell, John H

    2009-05-01

    The percentages of total airflows over the nasal respiratory and olfactory epithelium of female rabbits were calculated from computational fluid dynamics (CFD) simulations of steady-state inhalation. These airflow calculations, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water-soluble or reactive gases and vapors in rabbits. CFD simulations were based upon three-dimensional computational meshes derived from magnetic resonance images of three adult female New Zealand White (NZW) rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions in rats, mice, monkeys, or humans. This leads to a greater surface area to volume ratio in this region and thus the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable interanimal variability in the fine structures of the nasal turbinates and airflows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired airflows that reached the ethmoid turbinate region (approximately 50%) that is presumably lined with olfactory epithelium. These latter results (airflows reaching the ethmoid turbinate region) were higher than previous published estimates for the male F344 rat (19%) and human (7%). These differences in regional airflows can have significant implications in interspecies extrapolations of nasal dosimetry.

  10. Reversible and Irreversible Binding of Nanoparticles to Polymeric Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang H. Binder

    2009-01-01

    Full Text Available Reversible and irreversible binding of CdSe-nanoparticles and nanorods to polymeric surfaces via a strong, multiple hydrogen bond (= Hamilton-receptor/barbituric acid is described. Based on ROMP-copolymers, the supramolecular interaction on a thin polymer film is controlled by living polymerization methods, attaching the Hamilton-receptor in various architectures, and concentrations. Strong binding is observed with CdSe-nanoparticles and CdSe-nanorods, whose surfaces are equipped with matching barbituric acid-moieties. Addition of polar solvents, able to break the hydrogen bonds leads to the detachment of the nanoparticles from the polymeric film. Irreversible binding is observed if an azide/alkine-“click”-reaction is conducted after supramolecular recognition of the nanoparticles on the polymeric surface. Thus reversible or irreversible attachment of the nanosized objects can be achieved.

  11. Numerical Simulations of Airflow and Droplet Dispersion in a Horizontal Ammonia Scrubber

    DEFF Research Database (Denmark)

    Liu, Li; Nielsen, Peter Vilhelm; Heiselberg, Per Kvols

    2015-01-01

    Ammonia released in pig production industries can lead to eutrophication of surface waters, soil acidification, fertilization of vegetation and changes in ecosystems, etc. Air scrubbers with spray of aerosolized sulphur solution were used to remove the ammonia mixed in the airflow ventilated out...... plate or a flow straightener were tested. Impact of nozzle velocity and droplet residue size were analysed. It is found that additional input on the pump pressure to increase the injection velocity may not cause any more benefit in our cases, and the ammonia removal efficiency of the horizontal scrubber...... from a piggery. In this study, numerical method were used to investigate airflow pattern, droplet dispersion, ammonia absorption at droplet surface and overall removal efficiency in an air cleaner. Droplet trajectories and elapsed time in air were adopted to characterize the absorption efficiency...

  12. Occupational exposures to solvents and metals are associated with fixed airflow obstruction

    NARCIS (Netherlands)

    Alif, Sheikh M; Dharmage, Shyamali C; Benke, Geza; Dennekamp, Martine; Burgess, John A; Perret, Jennifer L; Lodge, Caroline J; Morrison, Stephen; Johns, David P; Giles, Graham G.; Gurrin, Lyle C; Thomas, Paul S; Hopper, John L; Wood-Baker, Richard; Thompson, Bruce R; Feather, Iain H; Vermeulen, Roel; Kromhout, Hans; Walters, E Haydn; Abramson, Michael J; Matheson, Melanie C

    2017-01-01

    Objectives This study investigated the associations between occupational exposures to solvents and metals and fixed airflow obstruction (AO) using post-bronchodilator spirometry. Methods We included 1335 participants from the 2002-2008 follow-up of the Tasmanian Longitudinal Health Study.

  13. The thermomechanics of nonlinear irreversible behaviors an introduction

    CERN Document Server

    Maugin, Gérard A

    1999-01-01

    In this invaluable book, macroscopic irreversible thermodynamics is presented in its realm and its splendor by appealing to the notion of internal variables of state. This applies to both fluids and solids with or without microstructures of mechanical or electromagnetic origin. This unmatched richness of essentially nonlinear behaviors is the result of the use of modern mathematical techniques such as convex analysis in a clear-cut framework which allows one to put under the umbrella of "irreversible thermodynamics" behaviors which until now have been commonly considered either not easily cove

  14. Time in Science: Reversibility vs. Irreversibility

    Science.gov (United States)

    Pomeau, Yves

    To discuss properly the question of irreversibility one needs to make a careful distinction between reversibility of the equations of motion and the choice of the initial conditions. This is also relevant for the rather confuse philosophy of the wave packet reduction in quantum mechanics. The explanation of this reduction requires also to make precise assumptions on what initial data are accessible in our world. Finally I discuss how a given (and long) time record can be shown in an objective way to record an irreversible or reversible process. Or: can a direction of time be derived from its analysis? This leads quite naturally to examine if there is a possible spontaneous breaking of the time reversal symmetry in many body systems, a symmetry breaking that would be put in evidence objectively by looking at certain specific time correlations.

  15. Changes in Peak Airflow Measurement During Maximal Cough After Vocal Fold Augmentation in Patients With Glottic Insufficiency.

    Science.gov (United States)

    Dion, Gregory R; Achlatis, Efstratios; Teng, Stephanie; Fang, Yixin; Persky, Michael; Branski, Ryan C; Amin, Milan R

    2017-11-01

    Compromised cough effectiveness is correlated with dysphagia and aspiration. Glottic insufficiency likely yields decreased cough strength and effectiveness. Although vocal fold augmentation favorably affects voice and likely improves cough strength, few data exist to support this hypothesis. To assess whether vocal fold augmentation improves peak airflow measurements during maximal-effort cough following augmentation. This case series study was conducted in a tertiary, academic laryngology clinic. Participants included 14 consecutive individuals with glottic insufficiency due to vocal fold paralysis, which was diagnosed via videostrobolaryngoscopy as a component of routine clinical examination. All participants who chose to proceed with augmentation were considered for the study whether office-based or operative augmentation was planned. Postaugmentation data were collected only at the first follow-up visit, which was targeted for 14 days after augmentation but varied on the basis of participant availability. Data were collected from June 5, 2014, to October 1, 2015. Data analysis took place between October 2, 2015, and March 3, 2017. Peak airflow during maximal volitional cough was quantified before and after vocal fold augmentation. Participants performed maximal coughs, and peak expiratory flow during the maximal cough was captured according to American Thoracic Society guidelines. Among the 14 participants (7 men and 7 women), the mean (SD) age was 62 (18) years. Three types of injectable material were used for vocal fold augmentation: carboxymethylcellulose in 5 patients, hyaluronic acid in 5, and calcium hydroxylapatite in 4. Following augmentation, cough strength increased in 11 participants and decreased cough strength was observed in 3. Peak airflow measurements during maximal cough varied from a decrease of 40 L/min to an increase of 150 L/min following augmentation. When preaugmentation and postaugmentation peak airflow measurements were compared, the

  16. Beach-dune dynamics: Spatio-temporal patterns of aeolian sediment transport under complex offshore airflow

    Science.gov (United States)

    Lynch, K.; Jackson, D.; Delgado-Fernandez, I.; Cooper, J. A.; Baas, A. C.; Beyers, M.

    2010-12-01

    This study examines sand transport and wind speed across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on the adjoining beach. Recent investigations of secondary airflow patterns over coastal dunes have suggested this may not be the case, that the turbulent nature of the airflow in these zones enhances sediment transport potential. Beach sediment may be delivered to the dune toe by re-circulating eddies under offshore winds in coastal areas, which may explain much of the dynamics of aeolian dunes on coasts where the dominant wind direction is offshore. The present study investigated aeolian sediment transport patterns under an offshore wind event. Empirical data were collected using load cell traps, for aeolian sediment transport, co-located with 3-D ultrasonic anemometers. The instrument positioning on the sub-aerial beach was informed by prior analysis of the airflow patterns using computational fluid dynamics. The array covered a total beach area of 90 m alongshore by 65 m cross-shore from the dune crest. Results confirm that sediment transport occurred in the ‘sheltered’ area under offshore winds. Over short time and space scales the nature of the transport is highly complex; however, preferential zones for sand entrainment may be identified. Alongshore spatial heterogeneity of sediment transport seems to show a relationship to undulations in the dune crest, while temporal and spatial variations may also be related to the position of the airflow reattachment zone. These results highlight the important feedbacks between flow characteristics and transport in a complex three dimensional surface.

  17. EFFECTS OF TEMPERATURE AND AIRFLOW ON VOLUME DEVELOPMENT DURING BAKING AND ITS INFLUENCE ON QUALITY OF CAKE

    OpenAIRE

    NURUL ATIQAH SANI; FARAH SALEENA TAIP; SITI MAZLINA MUSTAPA KAMAL; NORASHIKIN AB. AZIZ

    2014-01-01

    Volume and texture of cake are among the important parameters in measuring the quality of cake. The processing conditions play important roles in producing cakes of good quality. Recent studies focused more on the formulation and the manipulation of baking temperature, humidity and time instead of airflow condition. The objective of this study was to evaluate the effects of baking temperature and airflow on the volume development of cake and final cake quality such as volume development, firm...

  18. EVALUATION OF A KILN INCORPORATING AN OSCILLATING PLATE AIRFLOW SYSTEM

    OpenAIRE

    Campean,Mihaela; Marinescu,Ion; Ispas,Mihai

    2003-01-01

    Boards of spruce (Picea abies) were dried in a pilot kiln with an oscillating plate that provides -"alternating air movement in the stack". The paper outlines the airflow concept and provides results for drying time and quality.It is suggested that the system has certain advantages which make it suitable as an alternative to conventional drying, especially for small-sized enterprises

  19. Investigation on the effect of blending ratio and airflow rate on syngas profile produced from co-gasification of blended feedstock

    Directory of Open Access Journals (Sweden)

    Inayat Muddasser

    2017-01-01

    Full Text Available Shortages of feedstock supply due to seasonal availability, high transportation costs, and lack of biomass market are creating serious problems in continues operation of bioenergy industry. Aiming at this problem, utilization of blended feedstock is proposed. In this work blends of two different biomasses (wood and coconut shells were co-gasified using externally heated downdraft gasifier. The effects of varying biomass blending ratio and airflow rate on gaseous components of syngas and its heating value were investigated. The results obtained from the experiments revealed that W20:CS80 blend yielded higher values for H2 (20 Vol.% and HHV (18 MJ/Nm3 as compared to the other blends. The higher airflow rate has a negative effect on syngas profile and heating value. The CO and CH4 were observed higher at the start of the process, however, CO was observed decreasing afterward, and the CH4 dropped to 5.0 Vol.%. The maximum H2 and CH4 were obtained at 2.5 LPM airflow rate. The process was noticed more stable at low air flow rates. The HHV was observed higher at the start of process at low airflow rate. It is concluded that low airflow rate and a higher ratio of coconut shells can improve the syngas quality during co-gasification.

  20. Circulating activated innate lymphoid cells and mucosal-associated invariant T cells are associated with airflow limitation in patients with asthma.

    Science.gov (United States)

    Ishimori, Ayako; Harada, Norihiro; Chiba, Asako; Harada, Sonoko; Matsuno, Kei; Makino, Fumihiko; Ito, Jun; Ohta, Shoichiro; Ono, Junya; Atsuta, Ryo; Izuhara, Kenji; Takahashi, Kazuhisa; Miyake, Sachiko

    2017-04-01

    A variety of innate subsets of lymphoid cells such as natural killer (NK) cells, several populations of innate lymphoid cells (ILCs), and mucosal-associated invariant T (MAIT) cells as innate-like T lymphocytes are involved in asthma and may have important effector functions in asthmatic immune responses. In the present study, we investigated whether NK cells, ILCs, and MAIT cells in the peripheral blood of patients with asthma would be associated with clinical asthma parameters. We recruited 75 adult patients with mild to severe asthma. The peripheral blood mononuclear cells in peripheral venous blood samples from the patients were purified and stained with different combinations of appropriate antibodies. The cells were analyzed by flow cytometry. The percentage of activated (i.e., CD69 + ) NK cells in the total NK cell population was negatively correlated with FEV 1 % which is calculated by the forced expiratory volume in 1 s (FEV 1 )/the forced vital capacity (FVC). The percentages of CD69 + ILC1s and ILC2s were negatively correlated with FEV 1 % and %FEV 1 . The percentage of CD69 + ILC3s was positively correlated with BMI, and the percentage of CD69 + MAIT cells was negatively correlated with FEV 1 %. Moreover, the percentage of CD69 + NK cells, ILC1s, ILC2s, ILC3s, and MAIT cells were positively correlated with each other. For the first time, our data showed that activated NK cells, ILC1s, ILC2s, ILC3s, and MAIT cells were positively correlated with each other and may be associated with airflow limitation in patients with asthma. Copyright © 2016 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

  1. Irreversibility and Action of the Heat Conduction Process

    Directory of Open Access Journals (Sweden)

    Yu-Chao Hua

    2018-03-01

    Full Text Available Irreversibility (that is, the “one-sidedness” of time of a physical process can be characterized by using Lyapunov functions in the modern theory of stability. In this theoretical framework, entropy and its production rate have been generally regarded as Lyapunov functions in order to measure the irreversibility of various physical processes. In fact, the Lyapunov function is not always unique. In the represent work, a rigorous proof is given that the entransy and its dissipation rate can also serve as Lyapunov functions associated with the irreversibility of the heat conduction process without the conversion between heat and work. In addition, the variation of the entransy dissipation rate can lead to Fourier’s heat conduction law, while the entropy production rate cannot. This shows that the entransy dissipation rate, rather than the entropy production rate, is the unique action for the heat conduction process, and can be used to establish the finite element method for the approximate solution of heat conduction problems and the optimization of heat transfer processes.

  2. How to account for irreversibility in integrated assessment of climate change?; Comment tenir compte de l'irreversibilite dans l'evaluation integree du changement climatique?

    Energy Technology Data Exchange (ETDEWEB)

    Ha Duong, M

    1998-04-15

    How to account for irreversibility in integrated assessment of climate change? This Ph. D. thesis in Economics balances discounting, technical progress and the inertia of existing capital stock against uncertainty and the inertia of socio-economic systems to examine the issue of near term limitations of greenhouse gases emissions. After a general overview in chapter 2, and a more historical presentation of the debates in chapter 3, chapter 4 proceeds to review a large number of integrated assessment models. Chapter 5 introduces a Model on the Dynamics of Inertia and Adaptability of energy systems: DIAM, used to discuss how much previous studies might have overestimated the long term costs of CO{sub 2} limitations and underestimated adjustment costs. It shows that, given a target date for atmospheric CO{sub 2} concentration stabilisation, a higher inertia implies a lower optimal concentration trajectory. In a sequential decision framework, chapter 6 shows that current uncertainties about which CO{sub 2} concentration ceiling would not present dangerous interference with the climate system justifies precautionary action. Finally, chapter 7 uses the irreversibility effect theory to define formally situations of decision under controversy and compare the irreversibility of CO{sub 2} accumulation with the irreversibility of investments needed to moderate it. An option value for greenhouse gases emissions limitations is computed. (author)

  3. Numerical study of the air-flow in an oscillating water column wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Paixao Conde, J.M. [Department of Mechanical and Industrial Engineering, Faculty of Sciences and Technology, New University of Lisbon, Monte de Caparica, 2829-516 Caparica (Portugal); IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, 1049-001 Lisboa (Portugal); Gato, L.M.C. [IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, 1049-001 Lisboa (Portugal)

    2008-12-15

    The paper presents a numerical study of the air-flow in a typical pneumatic chamber geometry of an oscillating water column (OWC)-type wave energy converter (WEC), equipped with two vertical-axis air turbines, asymmetrically placed on the top of the chamber. Outwards and inwards, steady and periodic, air-flow calculations were performed to investigate the flow distribution at the turbines' inlet sections, as well as the properties of the air-jet impinging on the water free-surface. The original design of the OWC chamber is likely to be harmful for the operation of the turbines due to the possible air-jet-produced water-spray at the water free-surface subsequently ingested by the turbine. A geometry modification of the air chamber, using a horizontal baffle-plate to deflect the air from the turbines, is proposed and proved to be very effective in reducing the risk of water-spray production from the inwards flow. The flow distribution at the turbines' inlet sections for the outwards flow was found to be fairly uniform for the geometries considered, providing good inlet flow conditions for the turbines. Steady flow was found to be an acceptable model to study the air-flow inside the pneumatic chamber of an OWC-WEC. (author)

  4. Hybridized electromagnetic-triboelectric nanogenerator for scavenging air-flow energy to sustainably power temperature sensors.

    Science.gov (United States)

    Wang, Xue; Wang, Shuhua; Yang, Ya; Wang, Zhong Lin

    2015-04-28

    We report a hybridized nanogenerator with dimensions of 6.7 cm × 4.5 cm × 2 cm and a weight of 42.3 g that consists of two triboelectric nanogenerators (TENGs) and two electromagnetic generators (EMGs) for scavenging air-flow energy. Under an air-flow speed of about 18 m/s, the hybridized nanogenerator can deliver largest output powers of 3.5 mW for one TENG (in correspondence of power per unit mass/volume: 8.8 mW/g and 14.6 kW/m(3)) at a loading resistance of 3 MΩ and 1.8 mW for one EMG (in correspondence of power per unit mass/volume: 0.3 mW/g and 0.4 kW/m(3)) at a loading resistance of 2 kΩ, respectively. The hybridized nanogenerator can be utilized to charge a capacitor of 3300 μF to sustainably power four temperature sensors for realizing self-powered temperature sensor networks. Moreover, a wireless temperature sensor driven by a hybridized nanogenerator charged Li-ion battery can work well to send the temperature data to a receiver/computer at a distance of 1.5 m. This work takes a significant step toward air-flow energy harvesting and its potential applications in self-powered wireless sensor networks.

  5. CFD modelling and wind tunnel validation of airflow through plant canopies using 3D canopy architecture

    International Nuclear Information System (INIS)

    Endalew, A. Melese; Hertog, M.; Delele, M.A.; Baetens, K.; Persoons, T.; Baelmans, M.; Ramon, H.; Nicolai, B.M.; Verboven, P.

    2009-01-01

    The efficiency of pesticide application to agricultural fields and the resulting environmental contamination highly depend on atmospheric airflow. A computational fluid dynamics (CFD) modelling of airflow within plant canopies using 3D canopy architecture was developed to understand the effect of the canopy to airflow. The model average air velocity was validated using experimental results in a wind tunnel with two artificial model trees of 24 cm height. Mean air velocities and their root mean square (RMS) values were measured on a vertical plane upstream and downstream sides of the trees in the tunnel using 2D hotwire anemometer after imposing a uniform air velocity of 10 m s -1 at the inlet. 3D virtual canopy geometries of the artificial trees were modelled and introduced into a computational fluid domain whereby airflow through the trees was simulated using Reynolds-Averaged Navier-Stokes (RANS) equations and k-ε turbulence model. There was good agreement of the average longitudinal velocity, U between the measurements and the simulation results with relative errors less than 2% for upstream and 8% for downstream sides of the trees. The accuracy of the model prediction for turbulence kinetic energy k and turbulence intensity I was acceptable within the tree height when using a roughness length (y 0 = 0.02 mm) for the surface roughness of the tree branches and by applying a source model in a porous sub-domain created around the trees. The approach was applied for full scale orchard trees in the atmospheric boundary layer (ABL) and was compared with previous approaches and works. The simulation in the ABL was made using two groups of full scale orchard trees; short (h = 3 m) with wider branching and long (h = 4 m) with narrow branching. This comparison showed good qualitative agreements on the vertical profiles of U with small local differences as expected due to the spatial disparities in tree architecture. This work was able to show airflow within and above the

  6. Multiscale Analysis of Time Irreversibility Based on Phase-Space Reconstruction and Horizontal Visibility Graph Approach

    Science.gov (United States)

    Zhang, Yongping; Shang, Pengjian; Xiong, Hui; Xia, Jianan

    Time irreversibility is an important property of nonequilibrium dynamic systems. A visibility graph approach was recently proposed, and this approach is generally effective to measure time irreversibility of time series. However, its result may be unreliable when dealing with high-dimensional systems. In this work, we consider the joint concept of time irreversibility and adopt the phase-space reconstruction technique to improve this visibility graph approach. Compared with the previous approach, the improved approach gives a more accurate estimate for the irreversibility of time series, and is more effective to distinguish irreversible and reversible stochastic processes. We also use this approach to extract the multiscale irreversibility to account for the multiple inherent dynamics of time series. Finally, we apply the approach to detect the multiscale irreversibility of financial time series, and succeed to distinguish the time of financial crisis and the plateau. In addition, Asian stock indexes away from other indexes are clearly visible in higher time scales. Simulations and real data support the effectiveness of the improved approach when detecting time irreversibility.

  7. Human perception of air movement. Impact of frequency and airflow direction on draught sensation

    Energy Technology Data Exchange (ETDEWEB)

    Genhong Zhou

    1999-08-01

    Draught is defined as an unwanted local cooling of the human body caused by air movement. Air velocity and temperature are the main characteristics of air movement in rooms. Characteristics of instantaneous air velocity and temperature records previously measured in ventilated indoor spaces were analyzed. Air velocity and temperature fluctuated randomly. The amplitude and frequency of the fluctuations changed over time. Air movements around the human body were measured with a three-dimensional laser Doppler amemometer. A new parameter, equivalent frequency, was defined as an integral single parameter for describing the frequency characteristics of air velocity. The equivalent frequency of a randomly fluctuating velocity is defined as the frequency of sinusoidal velocity fluctuations with the same ratio of the standard deviation of acceleration to the standard deviation of air velocity as in the random velocity fluctuations. The equivalent frequencies of numerous instantaneous air-velocity records measured in ventilated space were analysed. The equivalent frequency of an airflow in an indoor space was found to be 0.1 to 2 Hz. The equivalent frequencies of most of the airflows were between 0.2 and 0.6 Hz. The relation between equivalent frequency and mean air velocity and standard deviation was established. Experiments were performed to identify the impact of the equivalent frequency on the human perception of draught. Forty subjects (20 women and 20 men) were subjected to airflows from behind with mean air velocities of 0.1, 0.2 and 0.3 m/s, with equivalent frequencies from 0 to 1 Hz at an air temperature of 20 deg. C. In this human-subject experimental study the frequency was found to have a significant impact on draught sensation. Subjects were more sensitive to airflow at an equivalent frequency between 0.2 and 0.6 Hz. A mathematical model for the simulation of draught was established and a computer program was developed for simulating the draught. The program

  8. A kinetic equation for irreversible aggregation

    International Nuclear Information System (INIS)

    Zanette, D.H.

    1990-09-01

    We introduce a kinetic equation for describing irreversible aggregation in the ballistic regime, including velocity distributions. The associated evolution for the macroscopic quantities is studied, and the general solution for Maxwell interaction models is obtained in the Fourier representation. (author). 23 refs

  9. Anisotropic shift of the irreversibility line by neutron irradiation

    International Nuclear Information System (INIS)

    Sauerzopf, F.M.; Wiesinger, H.P.; Weber, H.W.; Crabtree, G.W.; Frischherz, M.C.; Kirk, M.A.

    1991-09-01

    The irreversibility line of high-T c superconductors is shifted considerably by irradiating the material with fast neutrons. The anisotropic and non-monotonous shift is qualitatively explained by a simple model based on an interaction between three pinning mechanisms, the intrinsic pinning by the ab-planes, the weak pinning by the pre-irradiation defect structure, and strong pinning by neutron induced defect cascades. A correlation between the cascade density and the position of the irreversibility line is observed

  10. Morphological measurements in computed tomography correlate with airflow obstruction in chronic obstructive pulmonary disease: systematic review and meta-analysis

    International Nuclear Information System (INIS)

    Xie, XueQian; Oudkerk, Matthijs; Vliegenthart, Rozemarijn; Jong, Pim A. de; Wang, Ying; Hacken, Nick H.T. ten; Miao, Jingtao; Zhang, GuiXiang; Bock, Geertruida H. de

    2012-01-01

    To determine the correlation between CT measurements of emphysema or peripheral airways and airflow obstruction in chronic obstructive pulmonary disease (COPD). PubMed, Embase and Web of Knowledge were searched from 1976 to 2011. Two reviewers independently screened 1,763 citations to identify articles that correlated CT measurements to airflow obstruction parameters of the pulmonary function test in COPD patients, rated study quality and extracted information. Three CT measurements were accessed: lung attenuation area percentage 1 %pred) and FEV 1 divided by the forced volume vital capacity. Seventy-nine articles (9,559 participants) were included in the systematic review, demonstrating different methodologies, measurements and CT airflow obstruction correlations. There were 15 high-quality articles (2,095 participants) in the meta-analysis. The absolute pooled correlation coefficients ranged from 0.48 (95 % CI, 0.40 to 0.54) to 0.65 (0.58 to 0.71) for inspiratory CT and 0.64 (0.53 to 0.72) to 0.73 (0.63 to 0.80) for expiratory CT. CT measurements of emphysema or peripheral airways are significantly related to airflow obstruction in COPD patients. CT provides a morphological method to investigate airway obstruction in COPD. (orig.)

  11. Measures of thermodynamic irreversibility in deterministic and stochastic dynamics

    International Nuclear Information System (INIS)

    Ford, Ian J

    2015-01-01

    It is generally observed that if a dynamical system is sufficiently complex, then as time progresses it will share out energy and other properties amongst its component parts to eliminate any initial imbalances, retaining only fluctuations. This is known as energy dissipation and it is closely associated with the concept of thermodynamic irreversibility, measured by the increase in entropy according to the second law. It is of interest to quantify such behaviour from a dynamical rather than a thermodynamic perspective and to this end stochastic entropy production and the time-integrated dissipation function have been introduced as analogous measures of irreversibility, principally for stochastic and deterministic dynamics, respectively. We seek to compare these measures. First we modify the dissipation function to allow it to measure irreversibility in situations where the initial probability density function (pdf) of the system is asymmetric as well as symmetric in velocity. We propose that it tests for failure of what we call the obversibility of the system, to be contrasted with reversibility, the failure of which is assessed by stochastic entropy production. We note that the essential difference between stochastic entropy production and the time-integrated modified dissipation function lies in the sequence of procedures undertaken in the associated tests of irreversibility. We argue that an assumed symmetry of the initial pdf with respect to velocity inversion (within a framework of deterministic dynamics) can be incompatible with the Past Hypothesis, according to which there should be a statistical distinction between the behaviour of certain properties of an isolated system as it evolves into the far future and the remote past. Imposing symmetry on a velocity distribution is acceptable for many applications of statistical physics, but can introduce difficulties when discussing irreversible behaviour. (paper)

  12. WIND TUNNEL RESEARCH ON THE INFLUENCE OF ACTIVE AIRFLOW ON THE LIFT FORCE GENERATED BY THE AIRFOIL

    Directory of Open Access Journals (Sweden)

    Paweł Magryta

    2013-09-01

    Full Text Available The paper discusses the results of wind tunnel tests of airfoils with additional active airflow applied to their upper surfaces. These studies were carried out for a range of velocities up to 28 m/s in an open wind tunnel. Several types of airfoils selected for the examination feature different geometries and are widely applied in today’s aviation industry. The changes in the lift and drag force generated by these airfoils were recorded during the study. The test bench for the tests was equipped with a compressor and a vacuum pump to enable airflow through some holes on the airfoil upper surface. A rapid prototyping method and a 3D printer based on a powder printing technique were applied to print the airfoils. All of their surfaces were subject to surface grinding to smooth their external surfaces. The wind tunnel tests with and without active airflow applied to airfoils are summarised in the paper.

  13. Study on airflow characteristics of rear wing of F1 car

    Science.gov (United States)

    Azmi, A. R. S.; Sapit, A.; Mohammed, A. N.; Razali, M. A.; Sadikin, A.; Nordin, N.

    2017-09-01

    The paper aims to investigate CFD simulation is carried out to investigate the airflow along the rear wing of F1 car with Reynold number of 3 × 106 and velocity, u = 43.82204 m/s. The analysis was done using 2-D model consists of main plane and flap wing, combined together to form rear wing module. Both of the aerofoil is placed inside a box of 350mm long and 220mm height according to regulation set up by FIA. The parameters for this study is the thickness and the chord length of the flap wing aerofoil. The simulations were performed by using FLUENT solver and k-kl-omega model. The wind speed is set up to 43 m/s that is the average speed of F1 car when cornering. This study uses NACA 2408, 2412, and 2415 for the flap wing and BE50 for the main plane. Each cases being simulated with a gap between the aerofoil of 10mm and 50mm when the DRS is activated. Grid independence test and validation was conduct to make sure the result obtained is acceptable. The goal of this study is to investigate aerodynamic behavior of airflow around the rear wing as well as to see how the thickness and the chord length of flap wing influence the airflow at the rear wing. The results show that increasing in thickness of the flap wing aerofoil will decreases the downforce. The results also show that although the short flap wing generate lower downforce than the big flap wing, but the drag force can be significantly reduced as the short flap wing has more change in angle of attack when it is activated. Therefore, the type of aerofoil for the rear wing should be decided according to the circuit track so that it can be fully optimized.

  14. Fundamental economic irreversibilities influence policies for enhancing international forest phytosanitary security

    Science.gov (United States)

    Thomas P. Holmes; Will Allen; Robert G. Haight; E. Carina H. Keskitalo; Mariella Marzano; Maria Pettersson; Christopher P. Quine; E. R. Langer

    2017-01-01

    National and international efforts to manage forest biosecurity create tension between opposing sources of ecological and economic irreversibility. Phytosanitary policies designed to protect national borders from biological invasions incur sunk costs deriving from economic and political irreversibilities that incentivizes wait-and-see decision-making. However, the...

  15. The use of TiO2 nanoparticles to reduce refrigerator ir-reversibility

    International Nuclear Information System (INIS)

    Padmanabhan, Venkataramana Murthy V.; Palanisamy, Senthilkumar

    2012-01-01

    Highlights: ► COP of hydrocarbons mixture VCRSs increases less when compared to R134a. ► Compressor ir-reversibility of VCRSs decreases by 33% (R134a), 14% (R436A and R436B). ► Total ir-reversibility of selected VCRSs decreases. ► Exergy efficiency of R134a is exceptionally low at lower reference temperature. ► Exergy efficiency of selected VCRSs increases. - Abstract: The ir-reversibility at the process of a vapour-compression refrigeration system (VCRS) with nanoparticles in the working fluid was investigated experimentally. Mineral oil (MO) with 0.1 g L −1 TiO 2 nanoparticles mixture were used as the lubricant instead of Polyol-ester (POE) oil in the R134a, R436A (R290/R600a-56/44-wt.%) and R436B (R290/R600a-52/48-wt.%)VCRSs. The VCRS ir-reversibility at the process with the nanoparticles was investigated using second law of thermodynamics. The results indicate that R134a, R436A and R436B and MO with TiO 2 nanoparticles work normally and safely in the VCRS. The VCRSs total ir-reversibility (529, 588 and 570 W) at different process was better than the R134a, R436A and R436B and POE oil system (777, 697 and 683 W). The same tests with Al 2 O 3 nanoparticles showed that the different nanoparticles properties have little effect on the VCRS ir-reversibility. Thus, TiO 2 nanoparticles can be used in VCRS with reciprocating compressor to considerably reduce ir-reversibility at the process.

  16. New method for evaluating irreversible adsorption and stationary phase bleed in gas chromatographic capillary columns.

    Science.gov (United States)

    Wright, Bob W; Wright, Cherylyn W

    2012-10-26

    A novel method is described for the evaluation of irreversible adsorption and column bleed in gas chromatographic (GC) columns using a tandem GC approach. This work specifically determined the degree of irreversible adsorption behavior of specific sulfur and phosphorous containing test probe compounds at levels ranging from approximately 50 picograms (pg) to 1 nanogram (ng) on selected gas chromatographic columns. This method does not replace existing evaluation methods that characterize reversible adsorption but provides an additional tool. The test compounds were selected due to their ease of adsorption and their importance in the specific trace analytical detection methodology being developed. Replicate chromatographic columns with 5% phenylmethylpolysiloxane (PMS), polyethylene glycol (wax), trifluoropropylpolysiloxane (TFP), or 78% cyanopropylpolysiloxane stationary phases from a variety of vendors were evaluated. As expected, the results demonstrate that the different chromatographic phases exhibit differing degrees of irreversible adsorption behavior. The results also indicate that all manufacturers do not produce equally inert columns nor are columns from a given manufacturer identical. The wax-coated columns for the test probes used were more inert as a group than 5% PMS coated columns, and they were more reproducibly manufactured. Both TFP and 78% cyanopropylpolysiloxane columns displayed superior inertness to the test compounds compared to either 5% PMS- or wax-coated columns. Irreversible adsorption behavior was characterized for a limited range of stationary phase film thicknesses. In addition, the method was shown effective for characterizing column bleed and methods to remove bleed components. This method is useful in screening columns for demanding applications and to obtain diagnostic information related to improved preparation methods. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. A Fingerprint Encryption Scheme Based on Irreversible Function and Secure Authentication

    Directory of Open Access Journals (Sweden)

    Yijun Yang

    2015-01-01

    Full Text Available A fingerprint encryption scheme based on irreversible function has been designed in this paper. Since the fingerprint template includes almost the entire information of users’ fingerprints, the personal authentication can be determined only by the fingerprint features. This paper proposes an irreversible transforming function (using the improved SHA1 algorithm to transform the original minutiae which are extracted from the thinned fingerprint image. Then, Chinese remainder theorem is used to obtain the biokey from the integration of the transformed minutiae and the private key. The result shows that the scheme has better performance on security and efficiency comparing with other irreversible function schemes.

  18. Association of emphysema-like lung on cardiac computed tomography and mortality in persons without airflow obstruction: the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study

    Science.gov (United States)

    Oelsner, Elizabeth C.; Hoffman, Eric A.; Folsom, Aaron R.; Carr, J. Jeffrey; Enright, Paul L.; Kawut, Steven M.; Kronmal, Richard; Lederer, David; Lima, Joao A. C.; Lovasi, Gina S.; Shea, Steven; Barr, R. Graham

    2015-01-01

    Background Whereas low lung function is known to predict mortality in the general population, the prognostic significance of emphysema on computed tomography (CT) in persons without chronic obstructive pulmonary disease (COPD) remains uncertain. Objective To determine whether greater emphysema-like lung on CT is associated with all-cause mortality among persons without airflow obstruction or COPD in the general population. Design Prospective cohort study. Setting Population-based, multiethnic sample from 6 US communities. Participants 2965 participants ages 45-84 years without airflow obstruction on spirometry. Measurements Emphysema-like lung was defined on cardiac CT as the number of lung voxels less than -950 Hounsfield Units, and was adjusted for the number of total imaged lung voxels. Results Among 2965 participants, 50.9% of whom never smoked, there were 186 deaths over a median of 6.2 years. Greater emphysema-like lung was independently associated with increased mortality (adjusted hazard ratio [HR]1.14 per one-half of the interquartile range, 95% CI 1.04-1.24, P=0.004), adjusting for potential confounders including cardiovascular risk factors and the forced expiratory volume in one second. Generalized additive models supported a linear association between emphysema-like lung and mortality without evidence for a threshold. The association was of greatest magnitude among smokers, although multiplicative interaction terms did not support effect modification by smoking status. Limitations Cardiac CT scans did not include lung apices. The number of deaths was limited among subgroup analyses. Conclusions Emphysema-like lung on CT was associated with all-cause mortality among persons without airflow obstruction or COPD in a general population sample, particularly among smokers. Recognition of the independent prognostic significance of emphysema on CT among patients without COPD on spirometry is warranted. Primary Funding Source NIH/NHLBI. PMID:25506855

  19. Emphysema predicts hospitalisation and incident airflow obstruction among older smokers: a prospective cohort study.

    Directory of Open Access Journals (Sweden)

    David A McAllister

    Full Text Available Emphysema on CT is common in older smokers. We hypothesised that emphysema on CT predicts acute episodes of care for chronic lower respiratory disease among older smokers.Participants in a lung cancer screening study age ≥ 60 years were recruited into a prospective cohort study in 2001-02. Two radiologists independently visually assessed the severity of emphysema as absent, mild, moderate or severe. Percent emphysema was defined as the proportion of voxels ≤ -910 Hounsfield Units. Participants completed a median of 5 visits over a median of 6 years of follow-up. The primary outcome was hospitalization, emergency room or urgent office visit for chronic lower respiratory disease. Spirometry was performed following ATS/ERS guidelines. Airflow obstruction was defined as FEV1/FVC ratio <0.70 and FEV1<80% predicted.Of 521 participants, 4% had moderate or severe emphysema, which was associated with acute episodes of care (rate ratio 1.89; 95% CI: 1.01-3.52 adjusting for age, sex and race/ethnicity, as was percent emphysema, with similar associations for hospitalisation. Emphysema on visual assessment also predicted incident airflow obstruction (HR 5.14; 95% CI 2.19-21.1.Visually assessed emphysema and percent emphysema on CT predicted acute episodes of care for chronic lower respiratory disease, with the former predicting incident airflow obstruction among older smokers.

  20. Reconstruction of sound source signal by analytical passive TR in the environment with airflow

    Science.gov (United States)

    Wei, Long; Li, Min; Yang, Debin; Niu, Feng; Zeng, Wu

    2017-03-01

    In the acoustic design of air vehicles, the time-domain signals of noise sources on the surface of air vehicles can serve as data support to reveal the noise source generation mechanism, analyze acoustic fatigue, and take measures for noise insulation and reduction. To rapidly reconstruct the time-domain sound source signals in an environment with flow, a method combining the analytical passive time reversal mirror (AP-TR) with a shear flow correction is proposed. In this method, the negative influence of flow on sound wave propagation is suppressed by the shear flow correction, obtaining the corrected acoustic propagation time delay and path. Those corrected time delay and path together with the microphone array signals are then submitted to the AP-TR, reconstructing more accurate sound source signals in the environment with airflow. As an analytical method, AP-TR offers a supplementary way in 3D space to reconstruct the signal of sound source in the environment with airflow instead of the numerical TR. Experiments on the reconstruction of the sound source signals of a pair of loud speakers are conducted in an anechoic wind tunnel with subsonic airflow to validate the effectiveness and priorities of the proposed method. Moreover the comparison by theorem and experiment result between the AP-TR and the time-domain beamforming in reconstructing the sound source signal is also discussed.

  1. Optima and bounds for irreversible thermodynamic processes

    International Nuclear Information System (INIS)

    Hoffmann, K.H.

    1990-01-01

    In this paper bounds and optima for irreversible thermodynamic processes and their application in different fields are discussed. The tools of finite time thermodynamics are presented and especially optimal control theory is introduced. These methods are applied to heat engines, including models of the Diesel engine and a light-driven engine. Further bounds for irreversible processes are introduced, discussing work deficiency and its relation to thermodynamic length. Moreover the problem of dissipation in systems composed of several subsystems is studied. Finally, the methods of finite time thermodynamics are applied to thermodynamic processes described on a more microscopic level. The process used as an example is simulated annealing. It is shown how optimal control theory is applied to find the optimal cooling schedule for this important stochastic optimization method

  2. A minimal dissipation type-based classification in irreversible thermodynamics and microeconomics

    Science.gov (United States)

    Tsirlin, A. M.; Kazakov, V.; Kolinko, N. A.

    2003-10-01

    We formulate the problem of finding classes of kinetic dependencies in irreversible thermodynamic and microeconomic systems for which minimal dissipation processes belong to the same type. We show that this problem is an inverse optimal control problem and solve it. The commonality of this problem in irreversible thermodynamics and microeconomics is emphasized.

  3. Optimization of the performance characteristics in an irreversible magnetic Brayton refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Hao; Liu Sanqiu

    2008-01-01

    An irreversible cycle model of magnetic Brayton refrigerators is established, in which the thermal resistance and irreversibility in the two adiabatic processes are taken into account. Expressions for several important performance parameters, such as the coefficient of performance, cooling rate and power input are derived. Moreover, the optimal performance parameters are obtained at the maximum coefficient of performance. The optimization region (or criteria) for an irreversible magnetic Brayton refrigerator is obtained. The results obtained here have general significance and will be helpful to understand deeply the performance of a magnetic Brayton refrigeration cycle

  4. BNNT-mediated irreversible electroporatio: its potential on cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Vittoria Raffa, Cristina Riggio, Michael W. Smith, Kevin C. Jordan, Wei Cao, Alfred Cuschieri

    2012-10-01

    Tissue ablation, i.e., the destruction of undesirable tissues, has become an important minimally invasive technique alternative to resection surgery for the treatment of tumours. Several methods for tissue ablation are based on thermal techniques using cold, e.g. cryosurgery [1] or heat, e.g. radiofrequency [2] or high-intensity focused ultrasound [3] or nanoparticle-mediated irradiation [4]. Alternatively, irreversible electroporation (IRE) has been proposed as non thermal technique for minimally invasive tissue ablation based on the use of electrical pulses. When the electric field is applied to a cell, a change in transmembrane potential is induced, which can cause biochemical and physiological changes of the cell. When the threshold value of the transmembrane potential is exceeded, the cell membrane becomes permeable, thus allowing entrance of molecules that otherwise cannot cross the membrane [5]. A further increase in the electric field intensity may cause irreversible membrane permeabilization and cell death. These pulses create irreversible defects (pores) in the cell membrane lipid bilayer, causing cell death through loss of cell homeostasis [6]. This is desirable in tumour ablation in order to produce large cell death, without the use of cytostatic drugs. A study of Davalos, Mir and Rubinsky showed that IRE can ablate substantial volumes of tissue without inducing a thermal effect and therefore serve as an independent and new tissue ablation modality; this opened the way to the use of IRE in surgery [7]. Their finding was subsequently confirmed in studies on cells [8], small animal models [9] and in large animal models in the liver [10] and the heart [11]. The most important finding in these papers is that irreversible electroporation produces precisely delineated ablation zones with cell scale resolution between ablated and non-ablated areas, without zones in which the extent of damage changes gradually as during thermal ablation. Furthermore, it is

  5. Fluctuation theorems in feedback-controlled open quantum systems: Quantum coherence and absolute irreversibility

    Science.gov (United States)

    Murashita, Yûto; Gong, Zongping; Ashida, Yuto; Ueda, Masahito

    2017-10-01

    The thermodynamics of quantum coherence has attracted growing attention recently, where the thermodynamic advantage of quantum superposition is characterized in terms of quantum thermodynamics. We investigate the thermodynamic effects of quantum coherent driving in the context of the fluctuation theorem. We adopt a quantum-trajectory approach to investigate open quantum systems under feedback control. In these systems, the measurement backaction in the forward process plays a key role, and therefore the corresponding time-reversed quantum measurement and postselection must be considered in the backward process, in sharp contrast to the classical case. The state reduction associated with quantum measurement, in general, creates a zero-probability region in the space of quantum trajectories of the forward process, which causes singularly strong irreversibility with divergent entropy production (i.e., absolute irreversibility) and hence makes the ordinary fluctuation theorem break down. In the classical case, the error-free measurement ordinarily leads to absolute irreversibility, because the measurement restricts classical paths to the region compatible with the measurement outcome. In contrast, in open quantum systems, absolute irreversibility is suppressed even in the presence of the projective measurement due to those quantum rare events that go through the classically forbidden region with the aid of quantum coherent driving. This suppression of absolute irreversibility exemplifies the thermodynamic advantage of quantum coherent driving. Absolute irreversibility is shown to emerge in the absence of coherent driving after the measurement, especially in systems under time-delayed feedback control. We show that absolute irreversibility is mitigated by increasing the duration of quantum coherent driving or decreasing the delay time of feedback control.

  6. Buccal infiltration versus inferior alveolar nerve block in mandibular 2nd premolars with irreversible pulpitis.

    Science.gov (United States)

    Yilmaz, K; Tunga, U; Ozyurek, T

    2018-04-01

    The purpose of this study is to compare the success rates of inferior alveolar nerve block (IANB) and buccal infiltration anesthesia of mandibular second premolar with irreversible pulpitis and to evaluate the level of patient discomfort with these methods. Forty patients, who had irreversible pulpitis in the mandibular 2 nd premolar teeth, were included in the study. Patients were randomly distributed in two groups. In one group IANB, in the other group buccal infiltration anesthesia were performed. The efficacy of these two different anesthesia techniques on the related teeth was investigated with the Heft-Parker visual analog scale. In addition, with a pulse oximetry device, the changes in the patients' heart rates were compared between the groups. The obtained data were evaluated statistically. Both anesthesia techniques reduced the pain significantly in patients before the administration (P 0.05). Both of the anesthesia techniques increased the heart rate (P < 0.05). The increase in the heart rate of the patients was significantly higher in the buccal infiltration anesthesia group than the other anesthesia group (P < 0.05). Within the limitation of this in vivo study, there was no difference between the efficacies of the buccal infiltration anesthesia and IANB anesthesia in the mandibular 2 nd premolar teeth with irreversible pulpitis. Buccal infiltration anesthesia caused more discomfort in the patients compared with the IANB during the administration.

  7. Treatment Outcomes of Full Pulpotomy as an Alternative to Tooth Extraction in Molars with Hyperplastic/Irreversible Pulpitis: A Case Report

    Science.gov (United States)

    Asgary, Saeed; Verma, Prashant; Nosrat, Ali

    2017-01-01

    Root canal therapy (RCT) is a common and successful treatment for irreversible pulpitis due to carious pulp exposure in mature permanent teeth. However, it is often an expensive procedure, may require multiple appointments, and requires a high level of training and clinical skill, specifically in molars. Uninsured patients, low-income patients, and patients with limited access to specialist care often elect for extraction of restorable teeth with irreversible pulpitis. There is a need for an alternative affordable treatment option to preserve their teeth and maintain chewing function. A case of pulpotomy using calcium-enriched mixture (CEM) cement in two maxillary molars (#14 and 15) in a healthy 36-year-old patient is presented. Both teeth were diagnosed with symptomatic hyperplastic/irreversible pulpitis. Patient did not have dental insurance, was unable to afford RCT, and refused to extract the teeth. CEM pulpotomy and amalgam build-ups were done as an alternative to extraction. At 2-year recall, both teeth were functional with no signs/symptoms of inflammation/infection. Periapical radiographs and 3D images showed normal PDL around all roots. Pulpotomy with CEM biomaterial might be a viable alternative to tooth extraction for mature permanent teeth with hyperplastic/irreversible pulpitis, and can result in long-term tooth retention and improved oral health. PMID:28512498

  8. Characterization of dust particles produced in an all-tungsten wall tokamak and potentially mobilized by airflow

    Energy Technology Data Exchange (ETDEWEB)

    Rondeau, A., E-mail: anthony.rondeau@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, SCA, 91192 Gif-sur-Yvette (France); Peillon, S.; Roynette, A.; Sabroux, J.-C.; Gelain, T.; Gensdarmes, F. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, SCA, 91192 Gif-sur-Yvette (France); Rohde, V. [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Grisolia, C. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Chassefière, E. [Laboratoire Géosciences Paris Sud (GEOPS), UMR 8148, Université Paris Sud, 91403 Orsay Cedex (France)

    2015-08-15

    At the starting of the shutdown of the AUG (ASDEX Upgrade: Axially Symmetric Divertor EXperiment) German tokamak, we collected particles deposited on the divertor surfaces by means of a dedicated device called “Duster Box”. This device allows to collect the particles using a controlled airflow with a defined shear stress. Consequently, the particles collected correspond to a potentially mobilizable fraction, by an airflow, of deposited dust. A total of more than 70,000 tungsten particles was, analysed showing a bimodal particle size distribution with a mode composed of flakes at 0.6 μm and a mode composed of spherical particles at 1.8 μm.

  9. Irreversible adsorption of phenolic compounds by activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Grant, T.M.; King, C.J.

    1988-12-01

    Studies were undertaken to determine the reasons why phenolic sorbates can be difficult to remove and recover from activated carbons. The chemical properties of the sorbate and the adsorbent surface, and the influences of changes in the adsorption and desorption conditions were investigated. Comparison of isotherms established after different contact times or at different temperatures indicated that phenolic compounds react on carbon surfaces. The reaction rate is a strong function of temperature. Regeneration of carbons by leaching with acetone recovered at least as much phenol as did regeneration with other solvents or with displacers. The physiochemical properties of adsorbents influences irreversible uptakes. Sorbates differed markedly in their tendencies to undergo irreversible adsorption. 64 refs., 47 figs., 32 tabs.

  10. Irreversible adsorption of phenolic compounds by activated carbons

    International Nuclear Information System (INIS)

    Grant, T.M.; King, C.J.

    1988-12-01

    Studies were undertaken to determine the reasons why phenolic sorbates can be difficult to remove and recover from activated carbons. The chemical properties of the sorbate and the adsorbent surface, and the influences of changes in the adsorption and desorption conditions were investigated. Comparison of isotherms established after different contact times or at different temperatures indicated that phenolic compounds react on carbon surfaces. The reaction rate is a strong function of temperature. Regeneration of carbons by leaching with acetone recovered at least as much phenol as did regeneration with other solvents or with displacers. The physiochemical properties of adsorbents influences irreversible uptakes. Sorbates differed markedly in their tendencies to undergo irreversible adsorption. 64 refs., 47 figs., 32 tabs

  11. Synthesis of Fluorophore-Doped Polystyrene Microspheres: Seed Material for Airflow Sensing.

    Science.gov (United States)

    Wohl, Christopher J; Kiefer, Jacob M; Petrosky, Brian J; Tiemsin, Pacita I; Lowe, K Todd; Maisto, Pietro M F; Danehy, Paul M

    2015-09-23

    Kiton red 620 (KR620) doped polystyrene latex microspheres (PSLs) were synthesized via soap-free emulsion polymerization to be utilized as a relatively nontoxic, fluorescent seed material for airflow characterization experiments. Poly(styrene-co-styrenesulfonate) was used as the PSL matrix to promote KR620 incorporation. Additionally, a bicarbonate buffer and poly(diallyldimethylammonium chloride), polyD, cationic polymer were added to the reaction solution to stabilize the pH and potentially influence the electrostatic interactions between the PSLs and dye molecules. A design of experiments (DOE) approach was used to efficiently investigate the variation of these materials. Using a 4-factor, 2-level response surface design with a center point, a series of experiments were performed to determine the dependence of these factors on particle diameter, diameter size distribution, fluorescent emission intensity, and KR620 retention. Using statistical analysis, the factors and factor interactions that most significantly affect the outputs were identified. These particles enabled velocity measurements to be made much closer to walls and surfaces than previously. Based on these results, KR620-doped PSLs may be utilized to simultaneously measure the velocity and mixing concentration, among other airflow parameters, in complex flows.

  12. Port contact systems for irreversible thermodynamical systems

    NARCIS (Netherlands)

    Eberard, D.; Maschke, B.M.; Schaft, A.J. van der

    2005-01-01

    In this paper we propose a definition of control contact systems, generalizing input-output Hamiltonian systems, to cope with models arising from irreversible Thermodynamics. We exhibit a particular subclass of these systems, called conservative, that leaves invariant some Legendre submanifold (the

  13. Classical many-body theory with retarded interactions: Dynamical irreversibility and determinism without probabilities

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, A.Yu., E-mail: Anatoly.Zakharov@novsu.ru; Zakharov, M.A., E-mail: ma_zakharov@list.ru

    2016-01-28

    The exact equations of motion for microscopic density of classical many-body system with account of inter-particle retarded interactions is derived. It is shown that interactions retardation leads to irreversible behavior of many-body systems. - Highlights: • A new form of equation of motion of classical many-body system is proposed. • Interactions retardation as one of the mechanisms of many-body system irreversibility. • Irreversibility and determinism without probabilities. • The possible way to microscopic foundation of thermodynamics.

  14. β-characterization by irreversibility analysis: A thermoeconomic diagnosis method

    International Nuclear Information System (INIS)

    Zaleta-Aguilar, Alejandro; Olivares-Arriaga, Abraham; Cano-Andrade, Sergio; Rodriguez-Alejandro, David A.

    2016-01-01

    This paper presents a reconciliation methodology for the diagnosis of energy systems. The methodology is based on the characterization of irreversibilities in the components of an energy system. These irreversibilities can be attributed to malfunctions or dysfunctions. The characterization of irreversibilities as presented here makes possible to reconcile the Actual Operating Condition (AOC) versus the Reference Operating Condition (ROC) of the energy system in a real-time manner. The diagnosis methodology introduces a parameter β, which represents the total exergy or useful work of a component in terms of its inlet and output streams at either design (full-load) or off-design (partial-load) conditions. The methodology is applied to the diagnosis of an actual Natural Gas Combined Cycle (NGCC) power plant. Data for the model is obtained directly from the plant by monitoring its performance at every time; thus, a real-time thermodynamic diagnosis for the system is obtained. Results show that the methodology presented here is able to detect and quantify the deviations on the performance of the NGCC power plant during its real-time operation. Based on the detection and quantification of these deviations, the user is able to make recommendations to schedule maintenance on the components where the irreversibilities are present. - Highlights: • A new methodology for thermoeconomic diagnosis of energy systems is presented. • A parameter β is defined for characterization of the components of an energy system. • The β characterization methodology is tested in a real 420 MW NGCC power plant. • Results show that the complexity of a diagnosis analysis is reduced substantially.

  15. Variability of Irreversible Poleward Transport in the Lower Stratosphere

    Science.gov (United States)

    Olsen, Mark; Douglass, Anne; Newman, Paul; Nash, Eric; Witte, Jacquelyn; Ziemke, Jerry

    2011-01-01

    The ascent and descent of the Brewer-Dobson circulation plays a large role in determining the distributions of many constituents in the extratropical lower stratosphere. However, relatively fast, quasi-horizontal transport out of the tropics and polar regions also significantly contribute to determining these distributions. The tropical tape recorder signal assures that there must be outflow from the tropics into the extratropical lower stratosphere. The phase of the quasi-biennial oscillation (QBO) and state of the polar vortex are known to modulate the transport from the tropical and polar regions, respectively. In this study we examine multiple years of ozone distributions in the extratropical lower stratosphere observed by the Aura Microwave Limb Sounder (MLS) and the Aura High Resolution Dynamic Limb Sounder (HIRDLS). The distributions are compared with analyses of irreversible, meridional isentropic transport. We show that there is considerable year-to-year seasonal variability in the amount of irreversible transport from the tropics, which is related to both the phase of the QBO and the state of the polar vortex. The reversibility of the transport is consistent with the number of observed breaking waves. The variability of the atmospheric index of refraction in the lower stratosphere is shown to be significantly correlated with the wave breaking and amount of irreversible transport. Finally, we will show that the seasonal extratropical stratosphere to troposphere transport of ozone can be substantially modulated by the amount of irreversible meridional transport in the lower stratosphere and we investigate how observable these differences are in data of tropospheric ozone.

  16. Quantum thermodynamics: Microscopic foundations of entropy and of entropy generation by irreversibility

    Directory of Open Access Journals (Sweden)

    Beretta, Gian Paolo

    2008-02-01

    Full Text Available What is the physical significance of entropy? What is the physical origin of irreversibility? Do entropy and irreversibility exist only for complex and macroscopic systems? Most physicists still accept and teach that the rationalization of these fundamental questions is given by Statistical Mechanics. Indeed, for everyday laboratory physics, the mathematical formalism of Statistical Mechanics (canonical and grand-canonical, Boltzmann, Bose-Einstein and Fermi-Dirac distributions allows a successful description of the thermodynamic equilibrium properties of matter, including entropy values. However, as already recognized by Schrodinger in 1936, Statistical Mechanics is impaired by conceptual ambiguities and logical inconsistencies, both in its explanation of the meaning of entropy and in its implications on the concept of state of a system. An alternative theory has been developed by Gyftopoulos, Hatsopoulos and the present author to eliminate these stumbling conceptual blocks while maintaining the mathematical formalism so successful in applications. To resolve both the problem of the meaning of entropy and that of the origin of irreversibility we have built entropy and irreversibility into the laws of microscopic physics. The result is a theory, that we call Quantum Thermodynamics, that has all the necessary features to combine Mechanics and Thermodynamics uniting all the successful results of both theories, eliminating the logical inconsistencies of Statistical Mechanics and the paradoxes on irreversibility, and providing an entirely new perspective on the microscopic origin of irreversibility, nonlinearity (therefore including chaotic behavior and maximal-entropy-generation nonequilibrium dynamics. In this paper we discuss the background and formalism of Quantum Thermodynamics including its nonlinear equation of motion and the main general results. Our objective is to show in a not-too-technical manner that this theory provides indeed a

  17. A new approach to irreversibility in deep inelastic collisions

    International Nuclear Information System (INIS)

    Nemes, M.C.

    1982-01-01

    We use concepts of statistical mechanics to discuss the irreversible character of the experimental data in deep inelastic collisions. A definition of irreversibility proposed by Ruch permits a unified overview on current theories which describe these reactions. An information theoretical analysis of the data leads to a Fokker-Planck equation for the collective variables (excitation energy, charge and mass). The concept of mixing distance can serve as a quantitative measure to characterize the 'approach to equilibrium'. We apply it to the brownian motion as an illustration and also to the phenomenological analysis of deep inelastic scattering data with interesting results. (orig.)

  18. Airflow characteristics in the occupied zone of ventilated spaces

    DEFF Research Database (Denmark)

    Hanzawa, H.; Melikov, Arsen Krikor; Fanger, Povl Ole

    1987-01-01

    raft is one of the most common causes of complaint in ventilated or air-conditioned spaces. Therefore, knowing the turbulent airflow in these spaces and the impact of this flow on the sensation of draft is very important. The characteristics of turbulent flow (turbulence intensity, length scales...... of turbulence, turbulence kinetic energy, etc. ) were investigated in 20 typically ventilated spaces. Relationships between these characteristics and the mean velocity were found. The turbulence energy spectra are similar to those in a fully developed turbulent flow. The spectra reveal the major contribution...

  19. Mechanical Design of a Performance Test Rig for the Turbine Air-Flow Task (TAFT)

    Science.gov (United States)

    Forbes, John C.; Xenofos, George D.; Farrow, John L.; Tyler, Tom; Williams, Robert; Sargent, Scott; Moharos, Jozsef

    2004-01-01

    To support development of the Boeing-Rocketdyne RS84 rocket engine, a full-flow, reaction turbine geometry was integrated into the NASA-MSFC turbine air-flow test facility. A mechanical design was generated which minimized the amount of new hardware while incorporating all test and instrumentation requirements. This paper provides details of the mechanical design for this Turbine Air-Flow Task (TAFT) test rig. The mechanical design process utilized for this task included the following basic stages: Conceptual Design. Preliminary Design. Detailed Design. Baseline of Design (including Configuration Control and Drawing Revision). Fabrication. Assembly. During the design process, many lessons were learned that should benefit future test rig design projects. Of primary importance are well-defined requirements early in the design process, a thorough detailed design package, and effective communication with both the customer and the fabrication contractors.

  20. Breathing life into dinosaurs: tackling challenges of soft-tissue restoration and nasal airflow in extinct species.

    Science.gov (United States)

    Bourke, Jason M; Porter, W M Ruger; Ridgely, Ryan C; Lyson, Tyler R; Schachner, Emma R; Bell, Phil R; Witmer, Lawrence M

    2014-11-01

    The nasal region plays a key role in sensory, thermal, and respiratory physiology, but exploring its evolution is hampered by a lack of preservation of soft-tissue structures in extinct vertebrates. As a test case, we investigated members of the "bony-headed" ornithischian dinosaur clade Pachycephalosauridae (particularly Stegoceras validum) because of their small body size (which mitigated allometric concerns) and their tendency to preserve nasal soft tissues within their hypermineralized skulls. Hypermineralization directly preserved portions of the olfactory turbinates along with an internal nasal ridge that we regard as potentially an osteological correlate for respiratory conchae. Fossil specimens were CT-scanned, and nasal cavities were segmented and restored. Soft-tissue reconstruction of the nasal capsule was functionally tested in a virtual environment using computational fluid dynamics by running air through multiple models differing in nasal soft-tissue conformation: a bony-bounded model (i.e., skull without soft tissue) and then models with soft tissues added, such as a paranasal septum, a scrolled concha, a branched concha, and a model combining the paranasal septum with a concha. Deviations in fluid flow in comparison to a phylogenetically constrained sample of extant diapsids were used as indicators of missing soft tissue. Models that restored aspects of airflow found in extant diapsids, such as appreciable airflow in the olfactory chamber, were judged as more likely. The model with a branched concha produced airflow patterns closest to those of extant diapsids. These results from both paleontological observation and airflow modeling indicate that S. validum and other pachycephalosaurids could have had both olfactory and respiratory conchae. Although respiratory conchae have been linked to endothermy, such conclusions require caution in that our re-evaluation of the reptilian nasal apparatus indicates that respiratory conchae may be more widespread

  1. Impact of airflow interaction on inhaled air quality and transport of contaminants in rooms with personalized and total volume ventilation

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Cermak, Radim; Kovar, O.

    2003-01-01

    The impact of airflow interaction on inhaled air quality and transport of contaminants between occupants was studied in regard to pollution from floor covering, human bioeffluents and exhaled air, with combinations of two personalized ventilation systems (PV) with mixing and displacement...... quality with personalized and mixing ventilation was higher or at least similar compared to mixing ventilation alone. In the case of PV combined with displacement ventilation, the interaction caused mixing of the room air, an increase in the transport of bioeffluents and exhaled air between occupants and...... ventilation. In total, 80 L/s of clean air supplied at 20°C was distributed between the ventilation systems at different combinations of personalized airflow rate. Two breathing thermal manikins were used to simulate occupants in a full-scale test room. Regardless of the airflow interaction, the inhaled air...

  2. Extremum principles for irreversible processes

    International Nuclear Information System (INIS)

    Hillert, M.; Agren, J.

    2006-01-01

    Hamilton's extremum principle is a powerful mathematical tool in classical mechanics. Onsager's extremum principle may play a similar role in irreversible thermodynamics and may also become a valuable tool. His principle may formally be regarded as a principle of maximum rate of entropy production but does not have a clear physical interpretation. Prigogine's principle of minimum rate of entropy production has a physical interpretation when it applies, but is not strictly valid except for a very special case

  3. Multiscale analysis of heart rate dynamics: entropy and time irreversibility measures.

    Science.gov (United States)

    Costa, Madalena D; Peng, Chung-Kang; Goldberger, Ary L

    2008-06-01

    Cardiovascular signals are largely analyzed using traditional time and frequency domain measures. However, such measures fail to account for important properties related to multiscale organization and non-equilibrium dynamics. The complementary role of conventional signal analysis methods and emerging multiscale techniques, is, therefore, an important frontier area of investigation. The key finding of this presentation is that two recently developed multiscale computational tools--multiscale entropy and multiscale time irreversibility--are able to extract information from cardiac interbeat interval time series not contained in traditional methods based on mean, variance or Fourier spectrum (two-point correlation) techniques. These new methods, with careful attention to their limitations, may be useful in diagnostics, risk stratification and detection of toxicity of cardiac drugs.

  4. Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies.

    Science.gov (United States)

    Dols, W Stuart; Emmerich, Steven J; Polidoro, Brian J

    2016-03-01

    Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the

  5. Model Experiments for the Determination of Airflow in Large Spaces

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    Model experiments are one of the methods used for the determination of airflow in large spaces. This paper will discuss the formation of the governing dimensionless numbers. It is shown that experiments with a reduced scale often will necessitate a fully developed turbulence level of the flow....... Details of the flow from supply openings are very important for the determination of room air distribution. It is in some cases possible to make a simplified supply opening for the model experiment....

  6. Risk Aversion, Price Uncertainty and Irreversible Investments

    NARCIS (Netherlands)

    van den Goorbergh, R.W.J.; Huisman, K.J.M.; Kort, P.M.

    2003-01-01

    This paper generalizes the theory of irreversible investment under uncertainty by allowing for risk averse investors in the absence of com-plete markets.Until now this theory has only been developed in the cases of risk neutrality, or risk aversion in combination with complete markets.Within a

  7. Interactions of bluff-body obstacles with turbulent airflows affecting evaporative fluxes from porous surfaces

    Science.gov (United States)

    Haghighi, Erfan; Or, Dani

    2015-11-01

    Bluff-body obstacles interacting with turbulent airflows are common in many natural and engineering applications (from desert pavement and shrubs over natural surfaces to cylindrical elements in compact heat exchangers). Even with obstacles of simple geometry, their interactions within turbulent airflows result in a complex and unsteady flow field that affects surface drag partitioning and transport of scalars from adjacent evaporating surfaces. Observations of spatio-temporal thermal patterns on evaporating porous surfaces adjacent to bluff-body obstacles depict well-defined and persistent zonation of evaporation rates that were used to construct a simple mechanistic model for surface-turbulence interactions. Results from evaporative drying of sand surfaces with isolated cylindrical elements (bluff bodies) subjected to constant turbulent airflows were in good agreement with model predictions for localized exchange rates. Experimental and theoretical results show persistent enhancement of evaporative fluxes from bluff-rough surfaces relative to smooth flat surfaces under similar conditions. The enhancement is attributed to formation of vortices that induce a thinner boundary layer over part of the interacting surface footprint. For a practical range of air velocities (0.5-4.0 m/s), low-aspect ratio cylindrical bluff elements placed on evaporating sand surfaces enhanced evaporative mass losses (relative to a flat surface) by up to 300% for high density of elements and high wind velocity, similar to observations reported in the literature. Concepts from drag partitioning were used to generalize the model and upscale predictions to evaporation from surfaces with multiple obstacles for potential applications to natural bluff-rough surfaces.

  8. Canonical formalism, fundamental equation, and generalized thermomechanics for irreversible fluids with heat transfer

    International Nuclear Information System (INIS)

    Sieniutycz, S.; Berry, R.S.

    1993-01-01

    A Lagrangian with dissipative (e.g., Onsager's) potentials is constructed for the field description of irreversible heat-conducting fluids, off local equilibrium. Extremum conditions of action yield Clebsch representations of temperature, chemical potential, velocities, and generalized momenta, including a thermal momentum introduced recently [R. L. Selinger and F. R. S. Whitham, Proc. R. Soc. London, Ser. A 302, 1 (1968); S. Sieniutycz and R. S. Berry, Phys. Rev. A 40, 348 (1989)]. The basic question asked is ''To what extent may irreversibility, represented by a given form of the entropy source, influence the analytical form of the conservation laws for the energy and momentum?'' Noether's energy for a fluid with heat flow is obtained, which leads to a fundamental equation and extended Hamiltonian dynamics obeying the second law of thermodynamics. While in the case of the Onsager potentials this energy coincides numerically with the classical energy E, it contains an extra term (vanishing along the path) still contributing to an irreversible evolution. Components of the energy-momentum tensor preserve all terms regarded standardly as ''irreversible'' (heat, tangential stresses, etc.) generalized to the case when thermodynamics includes the state gradients and the so-called thermal phase, which we introduce here. This variable, the Lagrange multiplier of the entropy generation balance, is crucial for consistent treatment of irreversible processes via an action formalism. We conclude with the hypothesis that embedding the first and second laws in the context of the extremal behavior of action under irreversible conditions may imply accretion of an additional term to the classical energy

  9. Poppet valve control of throat stability bypass to increase stable airflow range of a Mach 2.5. inlet with 60 percent internal contraction

    Science.gov (United States)

    Mitchell, G. A.; Sanders, B. W.

    1975-01-01

    The throat of a Mach 2.5 inlet with a coldpipe termination was fitted with a stability-bypass system. System variations included several stability bypass entrance configurations. Poppet valves controlled the bypass airflow. The inlet stable airflow range achieved with each configuration was determined for both steady state conditions and internal pulse transients. Results are compared with those obtained without a stability bypass system. Transient results were also obtained for the inlet with a choke point at the diffuser exit and for the inlet with large and small stability bypass plenum volumes. Poppet valves at the stability bypass exit provided the inlet with a stable airflow range of 20 percent or greater at all static and transient conditions.

  10. Health Technology Assessment of CEM Pulpotomy in Permanent Molars with Irreversible Pulpitis

    Science.gov (United States)

    Yazdani, Shahram; Jadidfard, Mohammad-Pooyan; Tahani, Bahareh; Kazemian, Ali; Dianat, Omid; Alim Marvasti, Laleh

    2014-01-01

    Introduction: Teeth with irreversible pulpitis usually undergo root canal therapy (RCT). This treatment modality is often considered disadvantageous as it removes vital pulp tissue and weakens the tooth structure. A relatively new concept has risen which suggests vital pulp therapy (VPT) for irreversible pulpitis. VPT with calcium enriched mixture (VPT/CEM) has demonstrated favorable treatment outcomes when treating permanent molars with irreversible pulpitis. This study aims to compare patient related factors, safety and organizational consideration as parts of health technology assessment (HTA) of the new VPT/CEM biotechnology when compared with RCT. Materials and Methods: Patient related factors were assessed by looking at short- and long-term clinical success; safety related factors were evaluated by a specialist committee and discussion board involved in formulating healthcare policies. Organizational evaluation was performed and the social implications were assessed by estimating the costs, availability, accessibility and acceptability. The impact of VPT/CEM biotechnology was assessed by investigating the incidence of irreversible pulpitis and the effect of this treatment on reducing the burden of disease. Results: VPT/CEM biotechnology was deemed feasible and acceptable like RCT; however, it was more successful, accessible, affordable, available and also safer than RCT. Conclusion: When considering socioeconomic implications on oral health status and oral health-related quality of life of VPT/CEM, the novel biotechnology can be more effective and more efficient than RCT in mature permanent molars with irreversible pulpitis. PMID:24396372

  11. Onsager's reciprocity theorem in extended irreversible thermodynamics

    International Nuclear Information System (INIS)

    Garcia-Colin, L.S.; Velasco, R.M.

    1992-01-01

    In this paper we shall discuss the Onsager relations for the transport coefficients in a dilute monatomic gas described by the extended irreversible thermodynamics. Our discussion is based on a 26 variables description of the system and its corresponding comparison with the kinetic reciprocity between coefficients is shown (Author)

  12. Lie-admissible invariant treatment of irreversibility for matter and antimatter at the classical and operator levels

    International Nuclear Information System (INIS)

    Santilli, R.M.

    2006-01-01

    It was generally believed throughout the 20th century that irreversibility is a purely classical event without operator counterpart. however, a classical irreversible system cannot be consistently decomposed into a finite number of reversible quantum particles (and. vive versa), thus establishing that the origin of irreversibility is basically unknown at the dawn of the 21-st century. To resolve this problem. we adopt the historical analytical representation of irreversibility by Lagrange and Hamilton, that with external terms in their analytic equations; we show that, when properly written, the brackets of the time evolution characterize covering Lie-admissible algebras; we prove that the formalism has fully consistent operator counterpart given by the Lie-admissible branch of hadronic mechanics; we identify mathematical and physical inconsistencies when irreversible formulations are treated with the conventional mathematics used for reversible systems; we show that when the dynamical equations are treated with a novel irreversible mathematics, Lie-admissible formulations are fully consistent because invariant at both the classical and operator levels; and we complete our analysis with a number of explicit applications to irreversible processes in classical mechanics, particle physics and thermodynamics. The case of closed-isolated systems verifying conventional total conservation laws, yet possessing an irreversible structure, is treated via the simpler Lie-isotopic branch of hadronic mechanics. The analysis is conducted for both matter and antimatter at the classical and operator levels to prevent insidious inconsistencies occurring for the sole study of matter or, separately, antimatter

  13. Logical reformulation of quantum mechanics. III. Classical limit and irreversibility

    International Nuclear Information System (INIS)

    Omnes, R.

    1988-01-01

    This paper deals with two questions: (1) It contains a proof of the fact that consistent quantum representations of logic tend to the classical representation of logic when Planck's constant tends to zero. This result is obtained by using the microlocal analysis of partial differential equations and the Weyl calculus, which turn out to be the proper mathematical framework for this type of problems. (2) The analysis of the limitations of this proof turn out to be of physical significance, in particular when one considers quantum systems having for their classical version a Kolmogorov K-system. These limitations are used to show the existence of a best classical description for such a system leading to an objective definition of entropy. It is shown that in such a description the approach to equilibrium is strictly reduced to a Markov process

  14. Measurement of local blood flow and oxygen consumption in evolving irreversible cerebral infarction: an in vivo study in man

    International Nuclear Information System (INIS)

    Baron, J.C.; Rougemont, D.; Lebrun-Grandie, P.; Bousser, M.G.; Cabanis, E.; Bories, J.; Comar, D.; Castaigne, P.

    1982-09-01

    Positron emission tomography (PET) allows in vivo measurement of local cerebral blood flow (1CBF), oxygen consumption rate (1CMRO 2 ) and glucose utilisation (1CMRG1c) in man. Although 1CMRG1c is accessible in animals, this is not the case for 1CMRO 2 , an excellent index of local functional state. PET imaging of the local interrelationship of CBF and metabolism in completed ischemic stroke has attracted considerable interest because of its potential to differentiate irreversibly damaged from viable tissue on the basis of the CBF- metabolism patterns. Several qualitative or semi-quantitative pioneering studies provided a limited insight into this question, while the single truly quantitative study was only briefly reported. We report here a detailed study of the local CBF-CMRO 2 quantitative patterns in irreversibly infarcted brain regions

  15. An analysis of heat removal during cryogen spray cooling and effects of simultaneous airflow application.

    Science.gov (United States)

    Torres, J H; Tunnell, J W; Pikkula, B M; Anvari, B

    2001-01-01

    Cryogen spray cooling (CSC) is a method used to protect the epidermis from non-specific thermal injury that may occur as a result of various dermatological laser procedures. However, better understanding of cryogen deposition and skin thermal response to CSC is needed to optimize the technique. Temperature measurements and video imaging were carried out on an epoxy phantom as well as human skin during CSC with and without simultaneous application of airflow which was intended to accelerate cryogen evaporation from the substrate surface. An inverse thermal conduction model was used to estimate heat flux and total heat removed. Lifetime of the cryogen film deposited on the surface of skin and epoxy phantom lasted several hundred milliseconds beyond the spurt, but could be reduced to the spurt duration by application of airflow. Values over 100 J/cm(3) were estimated for volumetric heat removed from the epidermis using CSC. "Film cooling" instead of "evaporative cooling" appears to be the dominant mode of CSC on skin. Estimated values of heat removed from the epidermis suggest that a cryogen spurt as long as 200 milliseconds is required to counteract heat generated by high laser fluences (e.g., in treatment of port wine stains) in patients with high concentration of epidermal melanin. Additional cooling beyond spurt termination can be avoided by simultaneous application of airflow, although it is unclear at the moment if avoiding the additional cooling would be beneficial in the actual clinical situation. Copyright 2001 Wiley-Liss, Inc.

  16. Spectral deformation techniques applied to the study of quantum statistical irreversible processes

    International Nuclear Information System (INIS)

    Courbage, M.

    1978-01-01

    A procedure of analytic continuation of the resolvent of Liouville operators for quantum statistical systems is discussed. When applied to the theory of irreversible processes of the Brussels School, this method supports the idea that the restriction to a class of initial conditions is necessary to obtain an irreversible behaviour. The general results are tested on the Friedrichs model. (Auth.)

  17. Articaine for supplemental intraosseous anesthesia in patients with irreversible pulpitis.

    Science.gov (United States)

    Bigby, Jason; Reader, Al; Nusstein, John; Beck, Mike; Weaver, Joel

    2006-11-01

    The purpose of this study was to determine the anesthetic efficacy and heart rate effect of 4% articaine with 1:100,000 epinephrine for supplemental intraosseous injection in mandibular posterior teeth diagnosed with irreversible pulpitis. Thirty-seven emergency patients, diagnosed with irreversible pulpitis of a mandibular posterior tooth, received an inferior alveolar nerve block and had moderate-to-severe pain upon endodontic access. The Stabident system was used to administer 1.8 ml of 4% articaine with 1:100,000 epinephrine. Success of the intraosseous injection was defined as none or mild pain upon endodontic access or initial instrumentation. The results demonstrated that anesthetic success was obtained in 86% (32 of 37) of the patients. Maximum mean heart rate was increased 32 beats/minute during the intraosseous injection. We can conclude that when the inferior alveolar nerve block fails to provide profound pulpal anesthesia, the intraosseous injection of 4% articaine with 1:100,000 epinephrine would be successful 86% of the time in achieving pulpal anesthesia in mandibular posterior teeth of patients presenting with irreversible pulpitis.

  18. FINITE TIME THERMODYNAMIC MODELING AND ANALYSIS FOR AN IRREVERSIBLE ATKINSON CYCLE

    Directory of Open Access Journals (Sweden)

    Yanlin Ge

    2010-01-01

    Full Text Available Performance of an air-standard Atkinson cycle is analyzed by using finite-time thermodynamics. The irreversible cycle model which is more close to practice is founded. In this model, the non-linear relation between the specific heats of working fluid and its temperature, the friction loss computed according to the mean velocity of the piston, the internal irreversibility described by using the compression and expansion efficiencies, and heat transfer loss are considered. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of internal irreversibility, heat transfer loss and friction loss on the cycle performance are analyzed. The results obtained in this paper may provide guidelines for the design of practical internal combustion engines.

  19. Ecological optimization and performance study of irreversible Stirling and Ericsson heat engines

    International Nuclear Information System (INIS)

    Tyagi, S K; Kaushik, S C; Salhotra, R

    2002-01-01

    The concept of finite time thermodynamics is used to determine the ecological function of irreversible Stirling and Ericsson heat engine cycles. The ecological function is defined as the power output minus power loss (irreversibility), which is the ambient temperature times, the entropy generation rate. The ecological function is maximized with respect to cycle temperature ratio and the expressions for the corresponding power output and thermal efficiency are derived at the optimal operating conditions. The effect of different operating parameters, the effectiveness on the hot, cold and the regenerative side heat exchangers, the cycle temperature ratio, heat capacitance ratio and the internal irreversibility parameter on the maximum ecological function are studied. It is found that the effect of regenerator effectiveness is more than the hot and cold side heat exchangers and the effect of the effectiveness on cold side heat exchanger is more than the effectiveness on the hot side heat exchanger on the maximum ecological function. It is also found that the effect of internal irreversibility parameter is more than the other parameters not only on the maximum ecological function but also on the corresponding power output and the thermal efficiency

  20. Performance characteristics and parametric optimization of an irreversible magnetic Ericsson heat-pump

    International Nuclear Information System (INIS)

    Wei Fang; Lin Guoxing; Chen Jincan; Brueck, Ekkes

    2011-01-01

    Taking into account the finite-rate heat transfer in the heat-transfer processes, heat leak between the two external heat reservoirs, regenerative loss, regeneration time, and internal irreversibility due to dissipation of the cycle working substance, an irreversible magnetic Ericsson heat-pump cycle is presented. On the basis of the thermodynamic properties of magnetic materials, the performance characteristics of the irreversible magnetic Ericsson heat-pump are investigated and the relationship between the optimal heating load and the coefficient of performance (COP) is derived. Moreover, the maximum heating load and the corresponding COP as well as the maximum COP and the corresponding heating load are obtained. Furthermore, the other optimal performance characteristics are discussed in detail. The results obtained here may provide some new information for the optimal parameter design and the development of real magnetic Ericsson heat-pumps. -- Research Highlights: →The effects of multi-irreversibilities on the performance of a magnetic heat-pump are revealed. →Mathematical expressions of the heating load and the COP are derived and the optimal performance and operating parameters are analyzed and discussed. →Several important performance bounds are determined.

  1. Ecological optimization and performance study of irreversible Stirling and Ericsson heat engines

    Science.gov (United States)

    Tyagi, S. K.; Kaushik, S. C.; Salhotra, R.

    2002-10-01

    The concept of finite time thermodynamics is used to determine the ecological function of irreversible Stirling and Ericsson heat engine cycles. The ecological function is defined as the power output minus power loss (irreversibility), which is the ambient temperature times, the entropy generation rate. The ecological function is maximized with respect to cycle temperature ratio and the expressions for the corresponding power output and thermal efficiency are derived at the optimal operating conditions. The effect of different operating parameters, the effectiveness on the hot, cold and the regenerative side heat exchangers, the cycle temperature ratio, heat capacitance ratio and the internal irreversibility parameter on the maximum ecological function are studied. It is found that the effect of regenerator effectiveness is more than the hot and cold side heat exchangers and the effect of the effectiveness on cold side heat exchanger is more than the effectiveness on the hot side heat exchanger on the maximum ecological function. It is also found that the effect of internal irreversibility parameter is more than the other parameters not only on the maximum ecological function but also on the corresponding power output and the thermal efficiency.

  2. Characterization of Pump-Induced Acoustics in Space Launch System Main Propulsion System Liquid Hydrogen Feedline Using Airflow Test Data

    Science.gov (United States)

    Eberhart, C. J.; Snellgrove, L. M.; Zoladz, T. F.

    2015-01-01

    High intensity acoustic edgetones located upstream of the RS-25 Low Pressure Fuel Turbo Pump (LPFTP) were previously observed during Space Launch System (STS) airflow testing of a model Main Propulsion System (MPS) liquid hydrogen (LH2) feedline mated to a modified LPFTP. MPS hardware has been adapted to mitigate the problematic edgetones as part of the Space Launch System (SLS) program. A follow-on airflow test campaign has subjected the adapted hardware to tests mimicking STS-era airflow conditions, and this manuscript describes acoustic environment identification and characterization born from the latest test results. Fluid dynamics responsible for driving discrete excitations were well reproduced using legacy hardware. The modified design was found insensitive to high intensity edgetone-like discretes over the bandwidth of interest to SLS MPS unsteady environments. Rather, the natural acoustics of the test article were observed to respond in a narrowband-random/mixed discrete manner to broadband noise thought generated by the flow field. The intensity of these responses were several orders of magnitude reduced from those driven by edgetones.

  3. Reversible and irreversible magnetization of the Chevrel-phase superconductor PbMo6S8

    International Nuclear Information System (INIS)

    Zheng, D.N.; Ramsbottom, H.D.; Hampshire, D.P.

    1995-01-01

    Magnetic measurements have been carried out on the hot-isostatically-pressed Chevrel-phase superconductor PbMo 6 S 8 at temperatures from 4.2 K to T c and for magnetic fields up to 12 T. The results show that for the PbMo 6 S 8 compound there is a wide magnetically reversible region, between the irreversibility field B irr and the upper critical field B c2 , on the isothermal magnetic hysteresis curves. The B irr (T) line, i.e., the irreversibility line, was found to obey a power-law expression: B irr =B * (1-T/T c ) α with α∼1.5. Magnetic relaxation measurements revealed that the flux-creep effect in the material studied is substantial and is greater than those observed in conventional metallic alloys, but smaller than in high-temperature superconductors. The existence of the irreversibility line and pronounced flux-creep effect in PbMo 6 S 8 is attributed to the short coherence length of the material. From the reversible magnetization data, the values of the penetration depth, the coherence length, and the critical fields are obtained together with the Ginzburg-Landau parameter κ. At 4.2 K, the critical current density J c is 10 9 A m -2 at zero field, and decreases to 2x10 8 A m -2 at 10 T. Pinning force curves measured at different temperatures obey a Kramer-scaling law of the form: F p (=J c xB)∝b 1/2 (1-b) 2 , which indicates that the J c is limited by one predominant flux-pinning mechanism

  4. Use of cadmium in solution in the EL 4 reactor moderator irreversible fixing of cadmium on the metallic surfaces; Utilisation du cadmium en solution dans le moderateur du reacteur EL 4 - fixation irreversible du cadmium sur les surfaces metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Croix, O; Paoli, O; Lecomte, J; Dolle, L; Gallic, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    In the framework of research into the poisoning of the EL-4 reactor by cadmium sulphate, measurements have been made by two different methods of the residual amounts of cadmium liable to be fixed irreversibly on the surfaces in contact with the heavy water. A marked influence of the pH has been noticed. The mechanism of the irreversible fixing is compatible with the hypothesis of an ion-exchange in the surface oxide layer. In a sufficiently wide range of pH the cadmium thus fixed causes very little residual poisoning. The stability of the cadmium sulphate solutions is however rather low in the conditions of poisoning. (authors) [French] Dans le cadre des etudes sur l'empoisonnement du reacteur EL-4 par le sulfate de cadmium, les quantites residuelles de cadmium susceptibles de se fixer irreversiblement sur les parois que mouillerait l'eau lourde, ont ete mesurees experimentalement par deux methodes differentes. On observe une influence nette du pH. Le mecanisme de la fixation irreversible est compatible avec l'hypothese d'un echange d'ions dans la pellicule d'oxyde superficielle. Dans des limites suffisamment larges de pH, la cadmium ainsi fixe n'occasionne pas d'empoisonnement residuel important. La stabilite des solutions de sulfate de cadmium dans les conditions de l'empoisonnement est cependant mediocre. (auteurs)

  5. Effect of laminar airflow ventilation on surgical site infections: a systematic review and meta-analysis.

    Science.gov (United States)

    Bischoff, Peter; Kubilay, N Zeynep; Allegranzi, Benedetta; Egger, Matthias; Gastmeier, Petra

    2017-05-01

    The role of the operating room's ventilation system in the prevention of surgical site infections (SSIs) is widely discussed, and existing guidelines do not reflect current evidence. In this context, laminar airflow ventilation was compared with conventional ventilation to assess their effectiveness in reducing the risk of SSIs. We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and WHO regional medical databases from Jan 1, 1990, to Jan 31, 2014. We updated the search for MEDLINE for the period between Feb 1, 2014, and May 25, 2016. We included studies most relevant to our predefined question: is the use of laminar airflow in the operating room associated with the reduction of overall or deep SSI as outcomes in patients of any age undergoing surgical operations? We excluded studies not relevant to the study question, studies not in the selected languages, studies published before Jan 1, 1990, or after May 25, 2016, meeting or conference abstracts, and studies of which the full text was not available. Data were extracted by two independent investigators, with disagreements resolved through further discussion. Authors were contacted if the full-text article was not available, or if important data or information on the paper's content was absent. Studies were assessed for publication bias. Grading of recommendations assessment, development, and evaluation was used to assess the quality of the identified evidence. Meta-analyses were done with RevMan (version 5.3). We identified 1947 records of which 12 observational studies were comparing laminar airflow ventilation with conventional turbulent ventilation in orthopaedic, abdominal, and vascular surgery. The meta-analysis of eight cohort studies showed no difference in risk for deep SSIs following total hip arthroplasty (330 146 procedures, odds ratio [OR] 1·29, 95% CI 0·98-1·71; p=0·07, I 2 =83%). For total knee arthroplasty, the meta-analysis of six cohort studies showed no difference

  6. Profit rate performance optimization for a generalized irreversible ...

    Indian Academy of Sciences (India)

    fer law system generalized irreversible combined refrigeration cycle model with finite-rate heat ...... Chen L, Sun F, Wu C 2004b Optimum allocation of heat exchanger area for refrigeration and air conditioning plants. Appl. Energy 77(3): 339– ...

  7. Field measurements of mean and turbulent airflow over a barchan sand dune

    Science.gov (United States)

    Weaver, Corinne M.; Wiggs, Giles F. S.

    2011-05-01

    Advances in our knowledge of the aeolian processes governing sand dune dynamics have been restricted by a reliance on measures of time-averaged airflow, such as shear velocity ( u*). It has become clear that such measures are incapable of explaining the complete dynamics of sediment transport across dune surfaces. Past evidence from wind tunnel and modelling studies has suggested that in some regions on a dune's surface the sediment transport might be better explained through investigations of the turbulent nature of the airflow. However, to date there have been no field studies providing data on the turbulent characteristics of the airflow around dunes with which to support or refute such hypotheses. The field investigation presented here provides mean and turbulent airflow measurements across the centre-line of a barchan sand dune in Namibia. Data were collected using arrays of sonic anemometers and were compared with sand flux data measured using wedge-shaped traps. Results support previously published data derived from wind tunnels and numerical models. The decline in mean wind velocity at the upwind toe of the dune is shown to coincide with a rise in turbulence, whilst mean velocity acceleration on the upper slope corresponds with a general decline in measured turbulence. Analysis of the components of Reynold shear stress ( -u'¯w'¯) and normal stresses ( u¯ and w2 ¯) supports the notion that the development of flow turbulence along the dune centre-line is likely to be associated with the interplay between streamline curvature and mean flow deceleration/acceleration. It is suggested that, due to the nature of its calculation, turbulence intensity is a measure of less practical use than direct assessments of the individual components of Reynolds stress, particularly the instantaneous horizontal streamwise component ( u2 ¯) and shear stress ( -uw¯). Whilst, increases in Reynolds shear stress and the horizontal streamwise component of stress in the toe

  8. Frequency of self-reported COPD exacerbation and airflow obstruction in five Latin American cities: the Proyecto Latinoamericano de Investigacion en Obstruccion Pulmonar (PLATINO) study.

    Science.gov (United States)

    Montes de Oca, Maria; Tálamo, Carlos; Halbert, Ronald J; Perez-Padilla, Rogelio; Lopez, Maria Victorina; Muiño, Adriana; Jardim, José Roberto B; Valdivia, Gonzalo; Pertuzé, Julio; Moreno, Dolores; Menezes, Ana Maria B

    2009-07-01

    Recurrent exacerbations are common in COPD patients. Limited information exists regarding exacerbation frequency in COPD patients from epidemiologic studies. We examined the frequency of self-reported exacerbations and the factors influencing exacerbation frequency among COPD patients in a population-based study conducted in Latin America. We used a post-bronchodilator FEV(1)/FVC ratio of < 0.70 to define COPD. Exacerbation was self-reported and defined by symptoms (deterioration of breathing symptoms that affected usual daily activities or caused missed work). Spirometry was performed in 5,314 subjects. There were 759 subjects with airflow limitation; of these, 18.2% reported ever having had an exacerbation, 7.9% reported having an exacerbation, and 6.2% reported having an exacerbation requiring at least a doctor visit within the past year. The proportion of individuals with an exacerbation significantly increased by Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages, from 4.2% in stage 1 to 28.9% in stages 3 and 4. The self-reported exacerbation rate was 0.58 exacerbations per year. The rate of exacerbations requiring at least a doctor visit and length of stay in hospital due to exacerbations also increased as COPD severity progressed. The factors associated with having an exacerbation in the past year were dyspnea, prior asthma diagnosis, receiving any respiratory therapy, and disease severity of GOLD stages 3 and 4. The proportion of individuals with airflow limitation and self-reported exacerbation increases as the disease severity progresses. Dyspnea, prior asthma diagnosis, receiving any respiratory therapy, and more severe obstruction were significantly associated with having an exacerbation in the past year.

  9. The effect of airflow on thermographically determined temperature of the distal forelimb of the horse.

    Science.gov (United States)

    Westermann, S; Stanek, C; Schramel, J P; Ion, A; Buchner, H H F

    2013-09-01

    Current literature suggests that thermographic imaging of horses should be performed in a draught-free room. However, studies on the effect of airflow on determined temperature have not been published. To investigate effects of airflow on thermographically determined temperature of horses' forelimbs; to assess the relationship of wind velocity, rectal temperature, ambient temperature and humidity. Thermographic images were obtained for the forelimbs of 6 horses in a draught-free room. Three replicates (R) with defined wind velocities (R1, 0.5-1.0 m/s; R2, 1.3-2.6 m/s; and R3, 3.0-4.0 m/s) were conducted. Each replicate consisted of a baseline image, a 15 min phase with the wind on and a 15 min phase with the wind off. We exposed only the right leg to airflow and determined the temperature by thermography with the wind on and wind off. Temperature differences between baseline and wind on, between wind on and wind off and between different wind velocities were analysed by a general linear model, Student's paired t test and ANOVA. After the onset of wind, the temperature on the right forelimb decreased within 1-3 min (by approximately 0.6°C at R1, 1.5°C at R2 and 2.1°C at R3). With the wind off, the temperature increased within 3 min (by approximately 1.2°C at R1, 1.7°C at R2 and 2.1°C at R3). With increasing wind velocity, the temperature differences between baseline and wind on and between wind on and wind off increased significantly. Barely noticeable wind velocities caused a decrease in thermographically determined temperatures of the forelimbs of the horse. Further research is required to assess the influence of airflow on other parts of the body and at different ambient temperatures, as well as the effect on horses with inflammatory lesions, especially of the distal limbs. It is essential for practitioners to perform thermography on horses in a draught-free environment in order to avoid false-positive or -negative diagnoses. © 2012 EVJ Ltd.

  10. The degree of irreversibility in deterministic finite automata

    DEFF Research Database (Denmark)

    Axelsen, Holger Bock; Holzer, Markus; Kutrib, Martin

    2016-01-01

    the language, and show that the degree induces a strict infinite hierarchy of languages. We examine how the degree of irreversibility behaves under the usual language operations union, intersection, complement, concatenation, and Kleene star, showing tight bounds (some asymptotically) on the degree....

  11. Exergetic efficiency optimization for an irreversible heat pump ...

    Indian Academy of Sciences (India)

    This paper deals with the performance analysis and optimization for irreversible heat pumps working on reversed Brayton cycle with constant-temperature heat reservoirs by taking exergetic efficiency as the optimization objective combining exergy concept with finite-time thermodynamics (FTT). Exergetic efficiency is ...

  12. Peptide Drug Release Behavior from Biodegradable Temperature-Responsive Injectable Hydrogels Exhibiting Irreversible Gelation

    Directory of Open Access Journals (Sweden)

    Kazuyuki Takata

    2017-10-01

    Full Text Available We investigated the release behavior of glucagon-like peptide-1 (GLP-1 from a biodegradable injectable polymer (IP hydrogel. This hydrogel shows temperature-responsive irreversible gelation due to the covalent bond formation through a thiol-ene reaction. In vitro sustained release of GLP-1 from an irreversible IP formulation (F(P1/D+PA40 was observed compared with a reversible (physical gelation IP formulation (F(P1. Moreover, pharmaceutically active levels of GLP-1 were maintained in blood after subcutaneous injection of the irreversible IP formulation into rats. This system should be useful for the minimally invasive sustained drug release of peptide drugs and other water-soluble bioactive reagents.

  13. Strain induced irreversible critical current degradation in highly dense Bi-2212 round wire

    CERN Document Server

    Bjoerstad, R; Rikel, M.O.; Ballarino, A; Bottura, L; Jiang, J; Matras, M; Sugano, M; Hudspeth, J; Di Michiel, M

    2015-01-01

    The strain induced critical current degradation of overpressure processed straight Bi 2212/Ag wires has been studied at 77 K in self-field. For the first time superconducting properties, lattice distortions, composite wire stress and strain have been measured simultaneously in a high energy synchrotron beamline. A permanent Ic degradation of 5% occurs when the wire strain exceeds 0.60%. At a wire strain of about 0.65% a drastic n value and Ic reduction occur, and the composite stress and the Bi-2212 lattice parameter reach a plateau, indicating Bi-2212 filament fracturing. The XRD measurements show that Bi-2212 exhibits linear elastic behaviour up to the irreversible strain limit.

  14. Irreversible Markov chains in spin models: Topological excitations

    Science.gov (United States)

    Lei, Ze; Krauth, Werner

    2018-01-01

    We analyze the convergence of the irreversible event-chain Monte Carlo algorithm for continuous spin models in the presence of topological excitations. In the two-dimensional XY model, we show that the local nature of the Markov-chain dynamics leads to slow decay of vortex-antivortex correlations while spin waves decorrelate very quickly. Using a Fréchet description of the maximum vortex-antivortex distance, we quantify the contributions of topological excitations to the equilibrium correlations, and show that they vary from a dynamical critical exponent z∼ 2 at the critical temperature to z∼ 0 in the limit of zero temperature. We confirm the event-chain algorithm's fast relaxation (corresponding to z = 0) of spin waves in the harmonic approximation to the XY model. Mixing times (describing the approach towards equilibrium from the least favorable initial state) however remain much larger than equilibrium correlation times at low temperatures. We also describe the respective influence of topological monopole-antimonopole excitations and of spin waves on the event-chain dynamics in the three-dimensional Heisenberg model.

  15. Anesthetic Efficacy in Irreversible Pulpitis: A Randomized Clinical Trial.

    Science.gov (United States)

    Allegretti, Carlos E; Sampaio, Roberta M; Horliana, Anna C R T; Armonia, Paschoal L; Rocha, Rodney G; Tortamano, Isabel Peixoto

    2016-01-01

    Inferior alveolar nerve block has a high failure rate in the treatment of mandibular posterior teeth with irreversible pulpitis. The aim of this study was to compare the anesthetic efficacy of 4% articaine, 2% lidocaine and 2% mepivacaine, all in combination with 1:100,000 epinephrine, in patients with irreversible pulpitis of permanent mandibular molars during a pulpectomy procedure. Sixty-six volunteers from the Emergency Center of the School of Dentistry, University of São Paulo, randomly received 3.6 mL of local anesthetic as a conventional inferior alveolar nerve block (IANB). The subjective signal of lip numbness, pulpal anesthesia and absence of pain during the pulpectomy procedure were evaluated respectively, by questioning the patient, stimulation using an electric pulp tester and a verbal analogue scale. All patients reported the subjective signal of lip numbness. Regarding pulpal anesthesia success as measured with the pulp tester, the success rate was respectively 68.2% for mepivacaine, 63.6% for articaine and 63.6% for lidocaine. Regarding patients who reported no pain or mild pain during the pulpectomy, the success rate was, respectively 72.7% for mepivacaine, 63.6% for articaine and 54.5% for lidocaine. These differences were not statistically significant. Neither of the solutions resulted in 100% anesthetic success in patients with irreversible pulpitis of mandibular molars.

  16. Performance analysis of air-standard Diesel cycle using an alternative irreversible heat transfer approach

    International Nuclear Information System (INIS)

    Al-Hinti, I.; Akash, B.; Abu-Nada, E.; Al-Sarkhi, A.

    2008-01-01

    This study presents the investigation of air-standard Diesel cycle under irreversible heat transfer conditions. The effects of various engine parameters are presented. An alternative approach is used to evaluate net power output and cycle thermal efficiency from more realistic parameters such as air-fuel ratio, fuel mass flow rate, intake temperature, engine design parameters, etc. It is shown that for a given fuel flow rate, thermal efficiency and maximum power output increase with decreasing air-fuel ratio. Also, for a given air-fuel ratio, the maximum power output increases with increasing fuel rate. However, the effect of the thermal efficiency is limited

  17. Sample size effect on the determination of the irreversibility line of high-Tc superconductors

    International Nuclear Information System (INIS)

    Li, Q.; Suenaga, M.; Li, Q.; Freltoft, T.

    1994-01-01

    The irreversibility lines of a high-J c superconducting Bi 2 Sr 2 Ca 2 Cu 3 O x /Ag tape were systematically measured upon a sequence of subdivisions of the sample. The irreversibility field H r (T) (parallel to the c axis) was found to change approximately as L 0.13 , where L is the effective dimension of the superconducting tape. Furthermore, it was found that the irreversibility line for a grain-aligned Bi 2 Sr 2 Ca 2 Cu 3 O x specimen can be approximately reproduced by the extrapolation of this relation down to a grain size of a few tens of micrometers. The observed size effect could significantly obscure the real physical meaning of the irreversibility lines. In addition, this finding surprisingly indicated that the Bi 2 Sr 2 Ca 2 Cu 2 O x /Ag tape and grain-aligned specimen may have similar flux line pinning strength

  18. Nocturnal airflow obstruction, histamine, and the autonomic central nervous system in children with allergic asthma

    NARCIS (Netherlands)

    van Aalderen, W. M.; Postma, D. S.; Koëter, G. H.; Knol, K.

    1991-01-01

    A study was carried out to investigate whether an imbalance in the autonomic nervous system or release of histamine, or both, is responsible for the nocturnal increase in airflow obstruction in asthmatic children. The study comprised 18 children with allergic asthma, nine with (group 1) and nine

  19. Irreversible absorption heat-pump and its optimal performance

    International Nuclear Information System (INIS)

    Chen Lingen; Qin Xiaoyong; Sun Fengrui; Wu Chih

    2005-01-01

    On the basis of an endoreversible absorption heat-pump cycle, a generalized irreversible four-heat-reservoir absorption heat-pump cycle model is established by taking account of the heat resistances, heat leak and irreversibilities due to the internal dissipation of the working substance. The heat transfer between the heat reservoir and the working substance is assumed to obey the linear (Newtonian) heat-transfer law, and the overall heat-transfer surface area of the four heat-exchangers is assumed to be constant. The fundamental optimal relations between the coefficient of performance (COP) and the heating-load, the maximum COP and the corresponding heating-load, the maximum heating load and the corresponding COP, as well as the optimal temperatures of the working substance and the optimal heat-transfer surface areas of the four heat-exchangers are derived by using finite-time thermodynamics. Moreover, the effects of the cycle parameters on the characteristics of the cycle are studied by numerical examples

  20. Quantum mechanical irreversibility and measurement

    CERN Document Server

    Grigolini, P

    1993-01-01

    This book is intended as a tutorial approach to some of the techniques used to deal with quantum dissipation and irreversibility, with special focus on their applications to the theory of measurements. The main purpose is to provide readers without a deep expertise in quantum statistical mechanics with the basic tools to develop a critical judgement on whether the major achievements in this field have to be considered a satisfactory solution of quantum paradox, or rather this ambitious achievement has to be postponed to when a new physics, more general than quantum and classical physics, will

  1. Airflow Characteristics at the Breathing Zone of a Seated Person

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Bolashikov, Zhecho Dimitrov; Nagano, Hideaki

    2011-01-01

    A method for active control over the interaction between the free convection flow around occupant‘s body and locally applied airflow from front on the velocity field at the breathing zone of a seated person was studied. A workplace equipped with personalised ventilation (PV) generating flow from......) was installed below the table board, above the thighs of the manikin, and was used to exhaust the air of the free convection flow coming from the lower body parts of the manikin. The velocity field at the breathing zone was measured with Particle Image Velocimetry consisting of a dual cavity laser and two CCD...

  2. Collective Odor Source Estimation and Search in Time-Variant Airflow Environments Using Mobile Robots

    Science.gov (United States)

    Meng, Qing-Hao; Yang, Wei-Xing; Wang, Yang; Zeng, Ming

    2011-01-01

    This paper addresses the collective odor source localization (OSL) problem in a time-varying airflow environment using mobile robots. A novel OSL methodology which combines odor-source probability estimation and multiple robots’ search is proposed. The estimation phase consists of two steps: firstly, the separate probability-distribution map of odor source is estimated via Bayesian rules and fuzzy inference based on a single robot’s detection events; secondly, the separate maps estimated by different robots at different times are fused into a combined map by way of distance based superposition. The multi-robot search behaviors are coordinated via a particle swarm optimization algorithm, where the estimated odor-source probability distribution is used to express the fitness functions. In the process of OSL, the estimation phase provides the prior knowledge for the searching while the searching verifies the estimation results, and both phases are implemented iteratively. The results of simulations for large-scale advection–diffusion plume environments and experiments using real robots in an indoor airflow environment validate the feasibility and robustness of the proposed OSL method. PMID:22346650

  3. Nonequilibrium and irreversibility

    CERN Document Server

    Gallavotti, Giovanni

    2014-01-01

    This book concentrates on the properties of the stationary states in chaotic systems of particles or fluids, leaving aside the theory of the way they can be reached. The stationary states of particles or of fluids (understood as probability distributions on microscopic configurations or on the fields describing continua) have received important new ideas and data from numerical simulations and reviews are needed. The starting point is to find out which time invariant distributions come into play in physics. A special feature of this book is the historical approach. To identify the problems the author analyzes the papers of the founding fathers Boltzmann, Clausius and Maxwell including translations of the relevant (parts of ) historical documents. He also establishes a close link between treatment of irreversible phenomena in statistical mechanics and the theory of chaotic systems at and beyond the onset of turbulence as developed by Sinai, Ruelle, Bowen (SRB) and others: the author gives arguments intending t...

  4. Investment Irreversibility and Precautionary Savings in General Equilibrium

    DEFF Research Database (Denmark)

    Ejarque, João

    than irreversibility effects. If shocks are idiosyncratic and affect a cross section of agents over capital, an increase in their variance may induce an increase in aggregate investment even if all agents have an incentive to invest less, because zero investment is now an active lower bound for part...

  5. Measuring Airflow in Local Exhaust Ventilation Systems. Module 23. Vocational Education Training in Environmental Sciences.

    Science.gov (United States)

    Consumer Dynamics Inc., Rockville, MD.

    This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on measuring airflow in local exhaust ventilation systems. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming each…

  6. Linear irreversible thermodynamics and Onsager reciprocity for information-driven engines

    Science.gov (United States)

    Yamamoto, Shumpei; Ito, Sosuke; Shiraishi, Naoto; Sagawa, Takahiro

    2016-11-01

    In the recent progress in nonequilibrium thermodynamics, information has been recognized as a kind of thermodynamic resource that can drive thermodynamic current without any direct energy injection. In this paper, we establish the framework of linear irreversible thermodynamics for a broad class of autonomous information processing. In particular, we prove that the Onsager reciprocity holds true with information: The linear response matrix is well-defined and is shown symmetric with both of the information affinity and the conventional thermodynamic affinity. As an application, we derive a universal bound for the efficiency at maximum power for information-driven engines in the linear regime. Our result reveals the fundamental role of information flow in linear irreversible thermodynamics.

  7. Mathematical models and equilibrium in irreversible microeconomics

    Directory of Open Access Journals (Sweden)

    Anatoly M. Tsirlin

    2010-07-01

    Full Text Available A set of equilibrium states in a system consisting of economic agents, economic reservoirs, and firms is considered. Methods of irreversible microeconomics are used. We show that direct sale/purchase leads to an equilibrium state which depends upon the coefficients of supply/demand functions. To reach the unique equilibrium state it is necessary to add either monetary exchange or an intermediate firm.

  8. Anistropically varying conductivity in irreversible electroporation simulations.

    Science.gov (United States)

    Labarbera, Nicholas; Drapaca, Corina

    2017-11-01

    One recent area of cancer research is irreversible electroporation (IRE). Irreversible electroporation is a minimally invasive procedure where needle electrodes are inserted into the body to ablate tumor cells with electricity. The aim of this paper is to propose a mathematical model that incorporates a tissue's conductivity increasing more in the direction of the electrical field as this has been shown to occur in experiments. It was necessary to mathematically derive a valid form of the conductivity tensor such that it is dependent on the electrical field direction and can be easily implemented into numerical software. The derivation of a conductivity tensor that can take arbitrary functions for the conductivity in the directions tangent and normal to the electrical field is the main contribution of this paper. Numerical simulations were performed for isotropic-varying and anisotropic-varying conductivities to evaluate the importance of including the electrical field's direction in the formulation for conductivity. By starting from previously published experimental results, this paper derived a general formulation for an anistropic-varying tensor for implementation into irreversible electroporation modeling software. The anistropic-varying tensor formulation allows the conductivity to take into consideration both electrical field direction and magnitude, as opposed to previous published works that only took into account electrical field magnitude. The anisotropic formulation predicts roughly a five percent decrease in ablation size for the monopolar simulation and approximately a ten percent decrease in ablation size for the bipolar simulations. This is a positive result as previously reported results found the isotropic formulation to overpredict ablation size for both monopolar and bipolar simulations. Furthermore, it was also reported that the isotropic formulation overpredicts the ablation size more for the bipolar case than the monopolar case. Thus, our

  9. Ecological optimization for an irreversible magnetic Ericsson refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Hao; Wu Guo-Xing

    2013-01-01

    An irreversible Ericsson refrigeration cycle model is established, in which multi-irreversibilities such as finite-rate heat transfer, regenerative loss, heat leakage, and the efficiency of the regenerator are taken into account. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance (COP), power input, exergy output rate, entropy generation rate, and ecological function are derived. The influences of the heat leakage and the time of the regenerative processes on the ecological performance of the refrigerator are analyzed. The optimal regions of the ecological function, cooling rate, and COP are determined and evaluated. Furthermore, some important parameter relations of the refrigerator are revealed and discussed in detail. The results obtained here have general significance and will be helpful in gaining a deep understanding of the magnetic Ericsson refrigeration cycle. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Detailed Modeling and Irreversible Transfer Process Analysis of a Multi-Element Thermoelectric Generator System

    Science.gov (United States)

    Xiao, Heng; Gou, Xiaolong; Yang, Suwen

    2011-05-01

    Thermoelectric (TE) power generation technology, due to its several advantages, is becoming a noteworthy research direction. Many researchers conduct their performance analysis and optimization of TE devices and related applications based on the generalized thermoelectric energy balance equations. These generalized TE equations involve the internal irreversibility of Joule heating inside the thermoelectric device and heat leakage through the thermoelectric couple leg. However, it is assumed that the thermoelectric generator (TEG) is thermally isolated from the surroundings except for the heat flows at the cold and hot junctions. Since the thermoelectric generator is a multi-element device in practice, being composed of many fundamental TE couple legs, the effect of heat transfer between the TE couple leg and the ambient environment is not negligible. In this paper, based on basic theories of thermoelectric power generation and thermal science, detailed modeling of a thermoelectric generator taking account of the phenomenon of energy loss from the TE couple leg is reported. The revised generalized thermoelectric energy balance equations considering the effect of heat transfer between the TE couple leg and the ambient environment have been derived. Furthermore, characteristics of a multi-element thermoelectric generator with irreversibility have been investigated on the basis of the new derived TE equations. In the present investigation, second-law-based thermodynamic analysis (exergy analysis) has been applied to the irreversible heat transfer process in particular. It is found that the existence of the irreversible heat convection process causes a large loss of heat exergy in the TEG system, and using thermoelectric generators for low-grade waste heat recovery has promising potential. The results of irreversibility analysis, especially irreversible effects on generator system performance, based on the system model established in detail have guiding significance for

  11. Irreversible JPEG 2000 compression of abdominal CT for primary interpretation: assessment of visually lossless threshold

    International Nuclear Information System (INIS)

    Lee, Kyoung Ho; Kim, Young Hoon; Kim, Bo Hyoung; Kim, Kil Joong; Kim, Tae Jung; Kim, Hyuk Jung; Hahn, Seokyung

    2007-01-01

    To estimate the visually lossless threshold for Joint Photographic Experts Group (JPEG) 2000 compression of contrast-enhanced abdominal computed tomography (CT) images, 100 images were compressed to four different levels: a reversible (as negative control) and irreversible 5:1, 10:1, and 15:1. By alternately displaying the original and the compressed image on the same monitor, six radiologists independently determined if the compressed image was distinguishable from the original image. For each reader, we compared the proportion of the compressed images being rated distinguishable from the original images between the reversible compression and each of the three irreversible compressions using the exact test for paired proportions. For each reader, the proportion was not significantly different between the reversible (0-1%, 0/100 to 1/100) and irreversible 5:1 compression (0-3%). However, the proportion significantly increased with the irreversible 10:1 (95-99%) and 15:1 compressions (100%) versus reversible compression in all readers (P < 0.001); 100 and 95% of the 5:1 compressed images were rated indistinguishable from the original images by at least five of the six readers and all readers, respectively. Irreversibly 5:1 compressed abdominal CT images are visually lossless and, therefore, potentially acceptable for primary interpretation. (orig.)

  12. Experimental investigation into heating and airflow in trombe walls and solar chimneys

    International Nuclear Information System (INIS)

    Habib, A.; Burek, S.

    2006-01-01

    Trombe Walls and solar chimneys are examples of passive solar air heating systems. However, the airflow and thermal efficiency characteristics of this type of system are not well understood, and partly for this reason, they are not commonly utilised. This paper reports on an experimental investigation into buoyancy-driven convection in a test rig designed to simulate the operation of a passive solar collector. The test rig comprised a vertical open-ended channel, approximately 1a square, heated from one side. The channel depth could be varied from 20mm to 110mm, and heating inputs varied from 200W to 1000W. Temperatures and airflow rates were measured and recorded, to characterise both steady-state and transient performance. The principal findings are: 1. Time constants (for heating)ranged typically between 30 and 70 minutes. 2. Flow regimes were mainly laminar (Reynolds number varing from ∼500 to ∼4000, depending on heat input and channel depth. 3. The thermal efficiency (as a solar collector and the heat transfer coefficient were functions of heat input, and were not depended on the channel depth. 4. The mass flow rate through the channel increased bath as the heat input increased and as the channel depth increased. The paper presents these findings and discusses their implications in more detail.(Author)

  13. Antimicrobial activity and properties of irreversible hydrocolloid impression materials incorporated with silver nanoparticles.

    Science.gov (United States)

    Ginjupalli, Kishore; Alla, Rama Krishna; Tellapragada, Chaitanya; Gupta, Lokendra; Upadhya Perampalli, Nagaraja

    2016-06-01

    Conventional spray and the immersion disinfection of irreversible hydrocolloid impression materials may lead to dimensional changes. The purpose of this in vitro study was to investigate the antimicrobial activity and properties of irreversible hydrocolloid impression materials incorporated with silver nanoparticles. The antimicrobial activity and properties of 2 commercially available irreversible hydrocolloid impression materials were evaluated after incorporating varying concentrations of silver nanoparticles. Antimicrobial activity was determined using the disk diffusion method. The gel strength, permanent deformation, flow, and gelation time were measured according to American Dental Association specification #18. Analysis of variance was used to identify the significant differences within and across the groups (α=.05). Adding silver nanoparticles to irreversible hydrocolloid impression materials resulted in superior antimicrobial activity without adversely affecting their properties. Adding silver nanoparticles to Zelgan significantly increased the gel strength compared with the control group, except at 5 wt%. However, the gel strength of Tropicalgin was unaffected except at 5 wt%. An increase in the permanent deformation was found with the incorporation of silver nanoparticles in both Zelgan and Tropicalgin. The flow of Zelgan increased with the incorporation of silver nanoparticles, whereas a decrease in the flow of Tropicalgin was observed at 1 wt% and 2 wt%. An increase in the gelation time of both Zelgan and Tropicalgin was observed with the incorporation of silver nanoparticles. Based on this in vitro study, silver nanoparticles can be incorporated into irreversible hydrocolloid impression materials as antimicrobial agents without adversely affecting their properties. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Prostaglandin E2 to diagnose between reversible and irreversible pulpitis.

    Science.gov (United States)

    Petrini, M; Ferrante, M; Ciavarelli, L; Brunetti, L; Vacca, M; Spoto, G

    2012-01-01

    The aim of this work is to verify a correlation between the grade of inflammation and the concentration of PGE2 in human dental pulp. A total of 25 human dental pulps were examined by histological analysis and radioimmunologic dosage of PGE2. The pulps used in this experiment were from healthy and symptomatic teeth; the first ones were collected from teeth destined to be extracted for orthodontic reasons. An increase was observed of PGE2 in reversible pulpitis compared with healthy pulps and with the irreversible pulpitis and the clear decrease of these when NSAIDs are taken. This study demonstrates that PGE2 level is correlated to histological analysis thus allowing to distinguish symptomatic teeth in reversible and irreversible pulpitis.

  15. Numerical simulation of airway dimension effects on airflow patterns and odorant deposition patterns in the rat nasal cavity.

    Directory of Open Access Journals (Sweden)

    Zehong Wei

    Full Text Available The sense of smell is largely dependent on the airflow and odorant transport in the nasal cavity, which in turn depends on the anatomical structure of the nose. In order to evaluate the effect of airway dimension on rat nasal airflow patterns and odorant deposition patterns, we constructed two 3-dimensional, anatomically accurate models of the left nasal cavity of a Sprague-Dawley rat: one was based on high-resolution MRI images with relatively narrow airways and the other was based on artificially-widening airways of the MRI images by referencing the section images with relatively wide airways. Airflow and odorant transport, in the two models, were determined using the method of computational fluid dynamics with finite volume method. The results demonstrated that an increase of 34 µm in nasal airway dimension significantly decreased the average velocity in the whole nasal cavity by about 10% and in the olfactory region by about 12% and increased the volumetric flow into the olfactory region by about 3%. Odorant deposition was affected to a larger extent, especially in the olfactory region, where the maximum odorant deposition difference reached one order of magnitude. The results suggest that a more accurate nasal cavity model is necessary in order to more precisely study the olfactory function of the nose when using the rat.

  16. Direct and irreversible inhibition of cyclooxygenase-1 by nitroaspirin (NCX 4016).

    Science.gov (United States)

    Corazzi, Teresa; Leone, Mario; Maucci, Raffaella; Corazzi, Lanfranco; Gresele, Paolo

    2005-12-01

    Benzoic acid, 2-(acetyl-oxy)-3-[(nitrooxy)methyl]phenyl ester (NCX 4016), a new drug made by an aspirin molecule linked, through a spacer, to a nitric oxide (NO)-donating moiety, is now under clinical testing for the treatment of atherothrombotic conditions. Aspirin exerts its antithrombotic activity by irreversibly inactivating platelet cyclooxygenase (COX)-1. NCX 4016 in vivo undergoes metabolism into deacetylated and/or denitrated metabolites, and it is not known whether NCX 4016 needs to liberate aspirin to inhibit COX-1, or whether it can block it as a whole molecule. The aim of our study was to evaluate the effects of NCX 4016 and its analog or metabolites on platelet COX-1 and whole blood COX-2 and on purified ovine COX (oCOX)-1 and oCOX-2. In particular, we have compared the mechanism by which NCX 4016 inhibits purified oCOX enzymes with that of aspirin using a spectrophotometric assay. All the NCX 4016 derivatives containing acetylsalicylic acid inhibited the activity of oCOX-1 and oCOX-2, whereas the deacetylated metabolites and the nitric oxide-donating moiety were inactive. Dialysis experiments showed that oCOX-1 inhibition by NCX 4016, similar to aspirin, is irreversible. Reversible COX inhibitors (indomethacin) or salicylic acid incubated with the enzyme before NCX 4016 prevent the irreversible inhibition of oCOX-1 by NCX 4016 as well as by aspirin. In conclusion, our data show that NCX 4016 acts as a direct and irreversible inhibitor of COX-1 and that the presence of a spacer and NO-donating moiety in the molecule slows the kinetics of COX-1 inhibition by NCX 4016, compared with aspirin.

  17. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Science.gov (United States)

    2010-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

  18. 42 CFR 84.156 - Airflow resistance test; Type C supplied-air respirator, demand class; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... C supplied-air respirator, demand class; minimum requirements. (a) Inhalation resistance shall not... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance test; Type C supplied-air respirator, demand class; minimum requirements. 84.156 Section 84.156 Public Health PUBLIC HEALTH SERVICE...

  19. NOCTURNAL AIR-FLOW OBSTRUCTION, HISTAMINE, AND THE AUTONOMIC CENTRAL-NERVOUS-SYSTEM IN CHILDREN WITH ALLERGIC-ASTHMA

    NARCIS (Netherlands)

    VANAALDEREN, WMC; POSTMA, DS; KOETER, GH; KNOL, K

    A study was carried out to investigate whether an imbalance in the autonomic nervous system or release of histamine, or both, is responsible for the nocturnal increase in airflow obstruction in asthmatic children. The study comprised 18 children with allergic asthma,nine with (group 1) and nine

  20. Performance analysis of air conditioning system and airflow simulation in an operating theater

    Science.gov (United States)

    Alhamid, Muhammad Idrus; Budihardjo, Rahmat

    2018-02-01

    The importance of maintaining performance of a hospital operating theater is to establish an adequate circulation of clean air within the room. The parameter of air distribution in a space should be based on Air Changes per Hour (ACH) to maintain a positive room pressure. The dispersion of airborne particles in the operating theater was governed by regulating the air distribution so that the operating theater meets clean room standards ie ISO 14664 and ASHRAE 170. Here, we introduced several input parameters in a simulation environment to observe the pressure distribution in the room. Input parameters were air temperature, air velocity and volumetric flow rate entering and leaving room for existing and designed condition. In the existing operating theatre, several observations were found. It was found that the outlet air velocity at the HEPA filter above the operating table was too high thus causing a turbulent airflow pattern. Moreover, the setting temperature at 19°C was found to be too low. The supply of air into the room was observed at lower than 20 ACH which is under the standard requirement. Our simulation using FloVent 8.2™ program showed that not only airflow turbulence could be reduced but also the amount of particle contamination could also be minimized.

  1. Effect of mobile laminar airflow units on airborne bacterial contamination during neurosurgical procedures.

    Science.gov (United States)

    von Vogelsang, A-C; Förander, P; Arvidsson, M; Löwenhielm, P

    2018-03-24

    Surgical site infections (SSIs) after neurosurgery are potentially life-threatening and entail great costs. SSIs may occur from airborne bacteria in the operating room, and ultraclean air is desired during infection-prone cleaning procedures. Door openings and the number of persons present in the operating room affect the air quality. Mobile laminar airflow (MLAF) units, with horizontal laminar airflow, have previously been shown to reduce airborne bacterial contamination. To assess the effect of MLAF units on airborne bacterial contamination during neurosurgical procedures. In a quasi-experimental design, bacteria-carrying particles (colony-forming units: cfu) during neurosurgical procedures were measured with active air-sampling in operating rooms with conventional turbulent ventilation, and with additional MLAF units. The MLAF units were shifted between operating rooms monthly. Colony-forming unit count and bacterial species detection were conducted after incubation. Data was collected for a period of 18 months. A total of 233 samples were collected during 45 neurosurgical procedures. The use of MLAF units significantly reduced the numbers of cfu in the surgical site area (P neurosurgery to ultraclean air levels. MLAF units are valuable when the main operating room ventilation system is unable to produce ultraclean air in infection-prone clean neurosurgery. Copyright © 2018 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  2. SEPARATE AND COMBINED EFFECTS OF CORTICOSTEROIDS AND BRONCHODILATORS ON AIR-FLOW OBSTRUCTION AND AIRWAY HYPERRESPONSIVENESS IN ASTHMA

    NARCIS (Netherlands)

    WEMPE, JB; POSTMA, DS; BREEDERVELD, N; ALTINGHEBING, D; VANDERMARK, TW; KOETER, GH

    We have investigated separate and interactive effects of corticosteroids and bronchodilators on airflow obstruction and airway hyperresponsiveness. Twelve allergic subjects with asthma were treated in a double-blind, crossover, randomized study with budesonide, 1.6 mg daily for 3 weeks, prednisone,

  3. Reduction of physical activity in daily life and its determinants in smokers without airflow obstruction.

    Science.gov (United States)

    Furlanetto, Karina Couto; Mantoani, Leandro Cruz; Bisca, Gianna; Morita, Andrea Akemi; Zabatiero, Juliana; Proença, Mahara; Kovelis, Demétria; Pitta, Fabio

    2014-04-01

    In smokers without airflow obstruction, detailed, objective and controlled quantification of the level of physical inactivity in daily life has never been performed. This study aimed to objectively assess the level of physical activity in daily life in adult smokers without airflow obstruction in comparison with matched non-smokers, and to investigate the determinants for daily physical activity in smokers. Sixty smokers (aged 50 (39-54) years) and 50 non-smokers (aged 48 (40-53) years) matched for gender, age, anthropometric characteristics, educational level, employment status and seasons of the year assessment period were cross-sectionally assessed regarding their daily physical activity with a step counter, besides assessment of lung function, functional exercise capacity, quality of life, anxiety, depression, self-reported comorbidities carbon monoxide level, nicotine dependence and smoking habits. When compared with non-smokers, smokers walked less in daily life (7923 ± 3558 vs 9553 ± 3637 steps/day, respectively), presented worse lung function, functional exercise capacity, quality of life, anxiety and depression. Multiple regression analyses identified functional exercise capacity, Borg fatigue, self-reported motivation/physical activity behaviour and cardiac disease as significant determinants of number of steps/day in smokers (partial r(2)  = 0.10, 0.12, 0.16 and 0.05; b = 15, -997, 1207 and -2330 steps/day, respectively; overall fit of the model R(2)  = 0.38; P smokers without airflow obstruction presented reduced level of daily physical activity. Functional exercise capacity, extended fatigue sensation, aspects of motivation/physical activity behaviour and self-reported cardiac disease are significant determinants of physical activity in daily life in smokers. © 2014 The Authors. Respirology © 2014 Asian Pacific Society of Respirology.

  4. On the existence of physiological age based on functional hierarchy: a formal definition related to time irreversibility.

    Science.gov (United States)

    Chauvet, Gilbert A

    2006-09-01

    The present approach of aging and time irreversibility is a consequence of the theory of functional organization that I have developed and presented over recent years (see e.g., Ref. 11). It is based on the effect of physically small and numerous perturbations known as fluctuations, of structural units on the dynamics of the biological system during its adult life. Being a highly regulated biological system, a simple realistic hypothesis, the time-optimum regulation between the levels of organization, leads to the existence of an internal age for the biological system, and time-irreversibility associated with aging. Thus, although specific genes are controlling aging, time-irreversibility of the system may be shown to be due to the degradation of physiological functions. In other words, I suggest that for a biological system, the nature of time is specific and is an expression of the highly regulated integration. An internal physiological age reflects the irreversible course of a living organism towards death because of the irreversible course of physiological functions towards dysfunction, due to the irreversible changes in the regulatory processes. Following the works of Prigogine and his colleagues in physics, and more generally in the field of non-integrable dynamical systems (theorem of Poincaré-Misra), I have stated this problem in terms of the relationship between the macroscopic irreversibility of the functional organization and the basic mechanisms of regulation at the lowest "microscopic" level, i.e., the molecular, lowest level of organization. The neuron-neuron elementary functional interaction is proposed as an illustration of the method to define aging in the nervous system.

  5. Effects of diffuser airflow minima on occupant comfort, air mixing, and building energy use (RP-1515)

    DEFF Research Database (Denmark)

    Arens, Edward; Zhang, Hui; Hoyt, Tyler

    2015-01-01

    There is great energy-saving potential in reducing variable air volume box minimum airflow set-points to about 10% of maximum. Typical savings are on the order of 10%-30% of total HVAC energy, remarkable for an inexpensive controls set-point change that properly maintains outside air ventilation....

  6. Pinning and irreversibility in superconducting bulk MgB{sub 2} with added nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Anurag [Superconductivity and Cryogenics Division, National Physical Laboratory (CSIR), New Delhi-110012 (India); Narlikar, A V, E-mail: anurag@mail.nplindia.ernet.i [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452017, MP (India)

    2009-12-15

    Resistance, R(T), and magnetization, M(B), studies on superconducting bulk MgB{sub 2} samples containing nanodiamonds (ND) as additives (wt% of ND: x = 0%, 1%, 3%, 5%, 7% and 10%) were recently published in two articles (Vajpayee et al 2007 Supercond. Sci. Technol. 20 S155, Vajpayee et al 2008 J. Appl. Phys. 103 07C708). The main observations reported were significant improvements in the critical current density J{sub c}(B), irreversibility line B{sub irr}(T) and upper critical field B{sub c2}(T) with ND addition. However, a closer look shows that as regards the potential of this technologically important material at higher magnetic fields and temperatures, there is still a lot of room for improvement. With that in mind we revisit the R(T) and M(B) data and analyze them, in the present work. We show that, despite ND addition, J{sub c} depends strongly on B in the high field region and tends to vanish at irreversibility lines that lie deep, i.e. at around 0.3 B{sub c2}(T), in the B-T phase diagram. The irreversibility lines, determined by R(T){yields}0 in the presence of B, are found to lie at around 0.5 B{sub c2}(T) in the phase diagram. These results for pinning and irreversibility lines are discussed in the light of various models such as those of surface sheath superconductivity, magnetically introduced percolation in polycrystalline MgB{sub 2}, thermally assisted flux motion (TAFM) and a modified flux line shear mechanism. Our analysis hints at TAFM and weak pinning channels with distributed superconducting properties percolating in our samples determining the irreversibility and pinning properties.

  7. Antibacterial efficacy and effect of chlorhexidine mixed with irreversible hydrocolloid for dental impressions: a randomized controlled trial.

    Science.gov (United States)

    Cubas, Glória; Valentini, Fernanda; Camacho, Guilherme Brião; Leite, Fábio; Cenci, Maximiliano Sérgio; Pereira-Cenci, Tatiana

    2014-01-01

    This study aimed to evaluate whether chlorhexidine mixed with irreversible hydrocolloid powder decreases microbial contamination during impression taking without affecting the resulting casts. Twenty volunteers were randomly divided into two groups (n = 10) according to the liquid used for impression taking in conjunction with irreversible hydrocolloid: 0.12% chlorhexidine or water. Surface roughness and dimensional stability of the casts were evaluated. Chlorhexidine mixed with irreversible hydrocolloid decreased the percentage of microorganisms when compared with water (P impression quality.

  8. Nasal lavage cellularity, grain dust, and airflow obstruction.

    Science.gov (United States)

    Blaski, C A; Watt, J L; Quinn, T J; Thorne, P S; Schwartz, D A

    1996-04-01

    To evaluate the clinical utility of nasal lavage (NL), we performed post-work shift NL on 172 grain workers and 78 postal worker control subjects. The grain worker group included a higher percentage of current smokers (25.7% vs 16.7%) and a lower percentage of former smokers (21.15% vs 35.9%) compared with the postal workers. The control subjects included more female workers and were slightly older than the grain workers. Compared with the postal workers, the grain workers were exposed to significantly greater concentrations of total dust (0.1 +/- 0.0 vs 6.8 +/- 1.4 mg/m3; mean +/- SEM) and total endotoxin (4.3 +/- 0.8 vs 2,372.4 +/- 653.8 endotoxin units/m3). NL from gain workers showed a higher concentration of total cells (55,000 +/- 14,000 vs 25,000 +/- 5,000 cells per milliliter; p=0.03), a higher concentration of squamous epithelial cells (17,029.0 +/- 4,177 .0 vs 7,103.7 +/- 1,479.8 cells per milliliter; p=0.03), and a higher concentration of neutrophils (40,058.0 +/- 12,803.2 vs 17,891.0 +/- 3,822.3 cells per milliliter; p=0.10) compared with postal workers. Importantly, these differences in NL cellularity between grain workers and postal workers were observed within the three strata of smokers. To further assess the importance of total cells, squamous epithelial cells, and neutrophils in the NL fluid of grain workers, we investigated the relationship between these cell concentrations and (1) measures of dust and endotoxin exposure during the work shift. (2) spirometric measures of airflow obtained immediately before the NL, and (3) work-related respiratory symptoms. The concentration of total cells, the concentration of squamous epithelial cells, or the concentration of neutrophils in the NL was not associated with ambient levels of dust or endotoxin, with baseline or cross-shift changes in lung function, or with work-related respiratory symptoms. These findings suggest that increased NL cellularity may be seen in workers exposed to high dust levels

  9. Mechanics of airflow in the human nasal airways.

    Science.gov (United States)

    Doorly, D J; Taylor, D J; Schroter, R C

    2008-11-30

    The mechanics of airflow in the human nasal airways is reviewed, drawing on the findings of experimental and computational model studies. Modelling inevitably requires simplifications and assumptions, particularly given the complexity of the nasal airways. The processes entailed in modelling the nasal airways (from defining the model, to its production and, finally, validating the results) is critically examined, both for physical models and for computational simulations. Uncertainty still surrounds the appropriateness of the various assumptions made in modelling, particularly with regard to the nature of flow. New results are presented in which high-speed particle image velocimetry (PIV) and direct numerical simulation are applied to investigate the development of flow instability in the nasal cavity. These illustrate some of the improved capabilities afforded by technological developments for future model studies. The need for further improvements in characterising airway geometry and flow together with promising new methods are briefly discussed.

  10. Experimental study of airflow characteristics of stratum ventilation in a multi-occupant room with comparison to mixing ventilation and displacement ventilation.

    Science.gov (United States)

    Cheng, Y; Lin, Z

    2015-12-01

    The motivation of this study is stimulated by a lack of knowledge about the difference of airflow characteristics between a novel air distribution method [i.e., stratum ventilation (SV)] and conventional air distribution methods [i.e., mixing ventilation (MV) and displacement ventilation (DV)]. Detailed air velocity and temperature measurements were conducted in the occupied zone of a classroom with dimensions of 8.8 m (L) × 6.1 m (W) × 2.4 m (H). Turbulence intensity and power spectrum of velocity fluctuation were calculated using the measured data. Thermal comfort and cooling efficiency were also compared. The results show that in the occupied zone, the airflow characteristics among MV, DV, and SV are different. The turbulent airflow fluctuation is enhanced in this classroom with multiple thermal manikins due to thermal buoyancy and airflow mixing effect. Thermal comfort evaluations indicate that in comparison with MV and DV, a higher supply air temperature should be adopted for SV to achieve general thermal comfort with low draft risk. Comparison of the mean air temperatures in the occupied zone reveals that SV is of highest cooling efficiency, followed by DV and then MV. This study reports the unique profiles of flow, temperature, turbulence intensity, and power spectrum of stratum ventilation, which can have a number of implications for both knowledge and understanding of the flow characteristics in a stratum-ventilated room. With respect to the former, it expounds the fundamental characteristics of this air distribution method; and with respect to the latter, it reveals the mechanism of thermal comfort and energy saving under stratum ventilation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Inequalities for trace anomalies, length of the RG flow, distance between the fixed points and irreversibility

    International Nuclear Information System (INIS)

    Anselmi, Damiano

    2004-01-01

    I discuss several issues about the irreversibility of the RG flow and the trace anomalies c, a and a'. First I argue that in quantum field theory: (i) the scheme-invariant area Δ a' of the graph of the effective beta function between the fixed points defines the length of the RG flow; (ii) the minimum of Δ a' in the space of flows connecting the same UV and IR fixed points defines the (oriented) distance between the fixed points and (iii) in even dimensions, the distance between the fixed points is equal to Δ a = a UV - a IR . In even dimensions, these statements imply the inequalities 0 ≤ Δ a ≤ Δ a' and therefore the irreversibility of the RG flow. Another consequence is the inequality a ≤ c for free scalars and fermions (but not vectors), which can be checked explicitly. Secondly, I elaborate a more general axiomatic set-up where irreversibility is defined as the statement that there exist no pairs of non-trivial flows connecting interchanged UV and IR fixed points. The axioms, based on the notions of length of the flow, oriented distance between the fixed points and certain 'oriented-triangle inequalities', imply the irreversibility of the RG flow without a global a function. I conjecture that the RG flow is also irreversible in odd dimensions (without a global a function). In support of this, I check the axioms of irreversibility in a class of d = 3 theories where the RG flow is integrable at each order of the large N expansion

  12. Irreversible thermodynamics, parabolic law and self-similar state in grain growth

    International Nuclear Information System (INIS)

    Rios, P.R.

    2004-01-01

    The formalism of the thermodynamic theory of irreversible processes is applied to grain growth to investigate the nature of the self-similar state and its corresponding parabolic law. Grain growth does not reach a steady state in the sense that the entropy production remains constant. However, the entropy production can be written as a product of two factors: a scale factor that tends to zero for long times and a scaled entropy production. It is suggested that the parabolic law and the self-similar state may be associated with the minimum of this scaled entropy production. This result implies that the parabolic law and the self-similar state have a sound irreversible thermodynamical basis

  13. The universal power and efficiency characteristics for irreversible reciprocating heat engine cycles

    CERN Document Server

    Qin Xiao Yong; Sun Feng Rui; Wu Chih

    2003-01-01

    The performance of irreversible reciprocating heat engine cycles with heat transfer loss and friction-like term loss is analysed using finite-time thermodynamics. The universal relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, and the optimal relation between power output and the efficiency of the cycles are derived. Moreover, analysis and optimization of the model were carried out in order to investigate the effect of cycle processes on the performance of the cycle using numerical examples. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson and Brayton cycles.

  14. A general nonlinear evolution equation for irreversible conservative approach to stable equilibrium

    International Nuclear Information System (INIS)

    Beretta, G.P.

    1986-01-01

    This paper addresses a mathematical problem relevant to the question of nonequilibrium and irreversibility, namely, that of ''designing'' a general evolution equation capable of describing irreversible but conservative relaxtion towards equilibrium. The objective is to present an interesting mathematical solution to this design problem, namely, a new nonlinear evolution equation that satisfies a set of very stringent relevant requirements. Three different frameworks are defined from which the new equation could be adopted, with entirely different interpretations. Some useful well-known mathematics involving Gram determinants are presented and a nonlinear evolution equation is given which meets the stringent design specifications

  15. Limiting processes in non-equilibrium classical statistical mechanics

    International Nuclear Information System (INIS)

    Jancel, R.

    1983-01-01

    After a recall of the basic principles of the statistical mechanics, the results of ergodic theory, the transient at the thermodynamic limit and his link with the transport theory near the equilibrium are analyzed. The fundamental problems put by the description of non-equilibrium macroscopic systems are investigated and the kinetic methods are stated. The problems of the non-equilibrium statistical mechanics are analyzed: irreversibility and coarse-graining, macroscopic variables and kinetic description, autonomous reduced descriptions, limit processes, BBGKY hierarchy, limit theorems [fr

  16. Effect of enzymatic pretreatment on the physical quality of plantain (Musa ssp., group AAB) employing airflow reversal drying.

    Science.gov (United States)

    Rodríguez-Miranda, J; Martínez-Sánchez, C E; Hernández-Santos, B; Juárez-Barrientos, J M; Ventura-Báez, E G; Herman-Lara, E

    2018-01-01

    This work aimed to evaluate the effect of enzymatic pretreatment on the color and texture of plantain ( Musa ssp., group AAB) dried by airflow reversal drying. Plantain slices 1.0 cm thick were used. Pretreatment with two commercial enzymes, Pectinex Ultra SPL ( Aspergillus aculeatus ) and Pectinex 3XL ( Aspergillus niger ), was performed. Drying kinetics were determined with and without pretreatment at temperatures of 50, 65 and 80 °C using a fixed bed convective dryer. An air speed of 6 m/s, a bed height of 5 cm and either unidirectional flow or airflow reversal (every 15 min) were used for drying. Color and texture were analyzed, and consumer acceptance of the results of the best treatments was determined. Pretreatment with the enzyme A. niger and airflow reversal gave the best drying kinetics and showed the greatest reduction in drying time (59.0%) at 80 °C. The best hardness results were found at 80 °C with A. niger enzymatic pretreatment with both types of air flow. Brightness and hue angle showed that samples pretreated with enzymes and dried at 65 °C had a lighter yellow color compared to non-pretreated samples. Plantain samples enzymatically pretreated and dried at 65 and 80 °C were the most accepted by consumers. This kind of enzymatic pretreatment on plantain could allow the conservation of some physical properties and reduction of drying times relative to the current methodology.

  17. CITRIC-ACID COUGH THRESHOLD AND AIRWAY RESPONSIVENESS IN ASTHMATIC-PATIENTS AND SMOKERS WITH CHRONIC AIR-FLOW OBSTRUCTION

    NARCIS (Netherlands)

    AUFFARTH, B; DEMONCHY, JGR; VANDERMARK, TW; POSTMA, DS; KOETER, GH

    The relation between citric acid cough threshold and airway hyperresponsiveness was investigated in 11 non-smoking patients with allergic asthma (mean FEV1 94% predicted) and 25 non-atopic smokers with chronic airflow obstruction (mean FEV1 65% predicted). Cough threshold was determined on two

  18. Irreversibility analysis for gravity driven non-Newtonian liquid film along an inclined isothermal plate

    International Nuclear Information System (INIS)

    Makinde, O.D.

    2005-10-01

    In this paper, the first and second law of thermodynamics are employed in order to study the inherent irreversibility for a gravity driven non-Newtonian Ostwald-de Waele power law liquid film along an inclined isothermal plate. Based on some simplified assumptions, the governing equations are obtained and solved analytically. Expressions for fluid velocity, temperature, volumetric entropy generation numbers, irreversibility distribution ratio and the Bejan number are also determined. (author)

  19. Treatise on irreversible and statistical thermodynamics an introduction to nonclassical thermodynamics

    CERN Document Server

    Yourgrau, Wolfgang; Raw, Gough

    2002-01-01

    Extensively revised edition of a much-respected work examines thermodynamics of irreversible processes, general principles of statistical thermodynamics, assemblies of noninteracting structureless particles, and statistical theory. 1966 edition.

  20. Influence of delayed pouring on irreversible hydrocolloid properties

    Directory of Open Access Journals (Sweden)

    Stéfani Becker Rodrigues

    2012-10-01

    Full Text Available The aim of this study was to evaluate the physical properties of irreversible hydrocolloid materials poured immediately and after different storage periods. Four alginates were tested: Color Change (Cavex; Hydrogum (Zhermack; Hydrogum 5 (Zhermack; and Hydro Print Premium (Coltene. Their physical properties, including the recovery from deformation (n = 3, compressive strength (n = 3, and detail reproduction and gypsum compatibility (n = 3, were analyzed according to ANSI/ADA specification no. 18. Specimens were stored at 23ºC and humidity and were then poured with gypsum immediately and after 1, 2, 3, 4, and 5 days. The data were analyzed by two-way analysis of variance (ANOVA and Tukey's test at p < 0.05. All of the alginate impression materials tested exhibited detail reproduction and gypsum compatibility at all times. Hydro Print Premium and Hydrogum 5 showed recovery from deformation, as established by ANSI/ADA specification no. 18, after 5 days of storage. As the storage time increased, the compressive strength values also increased. Considering the properties of compounds' recovery from deformation, compressive strength, and detail reproduction and gypsum compatibility, irreversible hydrocolloids should be poured immediately.

  1. Irreversible entropy model for damage diagnosis in resistors

    Energy Technology Data Exchange (ETDEWEB)

    Cuadras, Angel, E-mail: angel.cuadras@upc.edu; Crisóstomo, Javier; Ovejas, Victoria J.; Quilez, Marcos [Instrumentation, Sensor and Interfaces Group, Electronic Engineering Department, Escola d' Enginyeria de Telecomunicació i Aeronàutica de Castelldefels EETAC, Universitat Politècnica de Catalunya, Barcelona Tech (UPC), Castelldefels-Barcelona (Spain)

    2015-10-28

    We propose a method to characterize electrical resistor damage based on entropy measurements. Irreversible entropy and the rate at which it is generated are more convenient parameters than resistance for describing damage because they are essentially positive in virtue of the second law of thermodynamics, whereas resistance may increase or decrease depending on the degradation mechanism. Commercial resistors were tested in order to characterize the damage induced by power surges. Resistors were biased with constant and pulsed voltage signals, leading to power dissipation in the range of 4–8 W, which is well above the 0.25 W nominal power to initiate failure. Entropy was inferred from the added power and temperature evolution. A model is proposed to understand the relationship among resistance, entropy, and damage. The power surge dissipates into heat (Joule effect) and damages the resistor. The results show a correlation between entropy generation rate and resistor failure. We conclude that damage can be conveniently assessed from irreversible entropy generation. Our results for resistors can be easily extrapolated to other systems or machines that can be modeled based on their resistance.

  2. Irreversible entropy model for damage diagnosis in resistors

    International Nuclear Information System (INIS)

    Cuadras, Angel; Crisóstomo, Javier; Ovejas, Victoria J.; Quilez, Marcos

    2015-01-01

    We propose a method to characterize electrical resistor damage based on entropy measurements. Irreversible entropy and the rate at which it is generated are more convenient parameters than resistance for describing damage because they are essentially positive in virtue of the second law of thermodynamics, whereas resistance may increase or decrease depending on the degradation mechanism. Commercial resistors were tested in order to characterize the damage induced by power surges. Resistors were biased with constant and pulsed voltage signals, leading to power dissipation in the range of 4–8 W, which is well above the 0.25 W nominal power to initiate failure. Entropy was inferred from the added power and temperature evolution. A model is proposed to understand the relationship among resistance, entropy, and damage. The power surge dissipates into heat (Joule effect) and damages the resistor. The results show a correlation between entropy generation rate and resistor failure. We conclude that damage can be conveniently assessed from irreversible entropy generation. Our results for resistors can be easily extrapolated to other systems or machines that can be modeled based on their resistance

  3. Advanced Caries Microbiota in Teeth with Irreversible Pulpitis.

    Science.gov (United States)

    Rôças, Isabela N; Lima, Kenio C; Assunção, Isauremi V; Gomes, Patrícia N; Bracks, Igor V; Siqueira, José F

    2015-09-01

    Bacterial taxa in the forefront of caries biofilms are candidate pathogens for irreversible pulpitis and are possibly the first ones to invade the pulp and initiate endodontic infection. This study examined the microbiota of the most advanced layers of dentinal caries in teeth with irreversible pulpitis. DNA extracted from samples taken from deep dentinal caries associated with pulp exposures was analyzed for the presence and relative levels of 33 oral bacterial taxa by using reverse-capture checkerboard hybridization assay. Quantification of total bacteria, streptococci, and lactobacilli was also performed by using real-time quantitative polymerase chain reaction. Associations between the target bacterial taxa and clinical signs/symptoms were also evaluated. The most frequently detected taxa in the checkerboard assay were Atopobium genomospecies C1 (53%), Pseudoramibacter alactolyticus (37%), Streptococcus species (33%), Streptococcus mutans (33%), Parvimonas micra (13%), Fusobacterium nucleatum (13%), and Veillonella species (13%). Streptococcus species, Dialister invisus, and P. micra were significantly associated with throbbing pain, S. mutans with pain to percussion, and Lactobacillus with continuous pain (P pulpitis is suspected. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  4. The classical Starling resistor model often does not predict inspiratory airflow patterns in the human upper airway.

    Science.gov (United States)

    Owens, Robert L; Edwards, Bradley A; Sands, Scott A; Butler, James P; Eckert, Danny J; White, David P; Malhotra, Atul; Wellman, Andrew

    2014-04-15

    The upper airway is often modeled as a classical Starling resistor, featuring a constant inspiratory airflow, or plateau, over a range of downstream pressures. However, airflow tracings from clinical sleep studies often show an initial peak before the plateau. To conform to the Starling model, the initial peak must be of small magnitude or dismissed as a transient. We developed a method to simulate fast or slow inspirations through the human upper airway, to test the hypothesis that this initial peak is a transient. Eight subjects [4 obstructive sleep apnea (OSA), 4 controls] slept in an "iron lung" and wore a nasal mask connected to a continuous/bilevel positive airway pressure machine. Downstream pressure was measured using an epiglottic catheter. During non-rapid eye movement (NREM) sleep, subjects were hyperventilated to produce a central apnea, then extrathoracic pressure was decreased slowly (∼2-4 s) or abruptly (resistor model, the upper airway exhibits marked NED in some subjects.

  5. Microbiome of Deep Dentinal Caries Lesions in Teeth with Symptomatic Irreversible Pulpitis.

    Science.gov (United States)

    Rôças, Isabela N; Alves, Flávio R F; Rachid, Caio T C C; Lima, Kenio C; Assunção, Isauremi V; Gomes, Patrícia N; Siqueira, José F

    2016-01-01

    This study used a next-generation sequencing approach to identify the bacterial taxa occurring in the advanced front of caries biofilms associated with pulp exposure and irreversible pulpitis. Samples were taken from the deepest layer of dentinal caries lesions associated with pulp exposure in 10 teeth diagnosed with symptomatic irreversible pulpitis. DNA was extracted and the microbiome was characterized on the basis of the V4 hypervariable region of the 16S rRNA gene by using paired-end sequencing on Illumina MiSeq device. Bacterial taxa were mapped to 14 phyla and 101 genera composed by 706 different OTUs. Three phyla accounted for approximately 98% of the sequences: Firmicutes, Actinobacteria and Proteobacteria. These phyla were also the ones with most representatives at the species level. Firmicutes was the most abundant phylum in 9/10 samples. As for genera, Lactobacillus accounted for 42.3% of the sequences, followed by Olsenella (13.7%), Pseudoramibacter (10.7%) and Streptococcus (5.5%). Half of the samples were heavily dominated by Lactobacillus, while in the other half lactobacilli were in very low abundance and the most dominant genera were Pseudoramibacter, Olsenella, Streptococcus, and Stenotrophomonas. High bacterial diversity occurred in deep dentinal caries lesions associated with symptomatic irreversible pulpitis. The microbiome could be classified according to the relative abundance of Lactobacillus. Except for Lactobacillus species, most of the highly prevalent and abundant bacterial taxa identified in this study have been commonly detected in infected root canals. The detected taxa can be regarded as candidate pathogens for irreversible pulpitis and possibly the pioneers in pulp invasion to initiate endodontic infection.

  6. Microbiome of Deep Dentinal Caries Lesions in Teeth with Symptomatic Irreversible Pulpitis.

    Directory of Open Access Journals (Sweden)

    Isabela N Rôças

    Full Text Available This study used a next-generation sequencing approach to identify the bacterial taxa occurring in the advanced front of caries biofilms associated with pulp exposure and irreversible pulpitis. Samples were taken from the deepest layer of dentinal caries lesions associated with pulp exposure in 10 teeth diagnosed with symptomatic irreversible pulpitis. DNA was extracted and the microbiome was characterized on the basis of the V4 hypervariable region of the 16S rRNA gene by using paired-end sequencing on Illumina MiSeq device. Bacterial taxa were mapped to 14 phyla and 101 genera composed by 706 different OTUs. Three phyla accounted for approximately 98% of the sequences: Firmicutes, Actinobacteria and Proteobacteria. These phyla were also the ones with most representatives at the species level. Firmicutes was the most abundant phylum in 9/10 samples. As for genera, Lactobacillus accounted for 42.3% of the sequences, followed by Olsenella (13.7%, Pseudoramibacter (10.7% and Streptococcus (5.5%. Half of the samples were heavily dominated by Lactobacillus, while in the other half lactobacilli were in very low abundance and the most dominant genera were Pseudoramibacter, Olsenella, Streptococcus, and Stenotrophomonas. High bacterial diversity occurred in deep dentinal caries lesions associated with symptomatic irreversible pulpitis. The microbiome could be classified according to the relative abundance of Lactobacillus. Except for Lactobacillus species, most of the highly prevalent and abundant bacterial taxa identified in this study have been commonly detected in infected root canals. The detected taxa can be regarded as candidate pathogens for irreversible pulpitis and possibly the pioneers in pulp invasion to initiate endodontic infection.

  7. Extended irreversible thermodynamics and the Jeffreys type constitutive equations

    International Nuclear Information System (INIS)

    Serdyukov, S.I.

    2003-01-01

    A postulate of extended irreversible thermodynamics is considered, according to which the entropy density is a function of the internal energy, the specific volume, and their material time derivatives. On the basis of this postulate, entropy balance equations and phenomenological equations are obtained, which directly lead to the Jeffreys type constitutive equations

  8. Effects of irreversibility and economics on the performance of a heat engine

    International Nuclear Information System (INIS)

    Ibrahim, O.M.; Klein, S.A.; Mitchell, J.W.

    1992-01-01

    In this paper, optimization of the power output of an internally irreversible heat engine is considered for finite capacitance rates of the external fluid streams. The method of Lagrange multipliers is used to solve for working fluid temperatures which yield maximum power. Analytical expressions for the maximum power and the cycle efficiency at miximum power are obtained. The effects of irreversibility and economics on the performance of a heat engine are investigated. A relationship between the maximum power point and economically optimum design is identified. It is demonstrated that, with certain reasonable economic assumptions, the maximum power point of a heat engine corresponds to a point of minimum life-cycle costs

  9. Ethacrynic acid improves the antitumor effects of irreversible epidermal growth factor receptor tyrosine kinase inhibitors in breast cancer.

    Science.gov (United States)

    Liu, Bing; Huang, XinPing; Hu, YunLong; Chen, TingTing; Peng, BoYa; Gao, NingNing; Jin, ZhenChao; Jia, TieLiu; Zhang, Na; Wang, ZhuLin; Jin, GuangYi

    2016-09-06

    Prolonged treatment of breast cancer with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) often results in acquired resistance and a narrow therapeutic index. One strategy to improve the therapeutic effects of EGFR TKIs is to combine them with drugs used for other clinical indications. Ethacrynic acid (EA) is an FDA approved drug that may have antitumor effects and may enhance the cytotoxicity of chemotherapeutic agents by binding to glutathione and inhibiting WNT signaling. While the α,β-unsaturated-keto structure of EA is similar to that of irreversible TKIs, the mechanism of action of EA when combined with irreversible EGFR TKIs in breast cancer remains unknown. We therefore investigated the combination of irreversible EGFR TKIs and EA. We found that irreversible EGFR TKIs and EA synergistically inhibit breast cancer both in vitro and in vivo. The combination of EGFR TKIs and EA induces necrosis and cell cycle arrest and represses WNT/β-catenin signaling as well as MAPK-ERK1/2 signaling. We conclude that EA synergistically enhances the antitumor effects of irreversible EGFR TKIs in breast cancer.

  10. Positive Feedback of NDT80 Expression Ensures Irreversible Meiotic Commitment in Budding Yeast

    Science.gov (United States)

    Tsuchiya, Dai; Yang, Yang; Lacefield, Soni

    2014-01-01

    In budding yeast, meiotic commitment is the irreversible continuation of the developmental path of meiosis. After reaching meiotic commitment, cells finish meiosis and gametogenesis, even in the absence of the meiosis-inducing signal. In contrast, if the meiosis-inducing signal is removed and the mitosis-inducing signal is provided prior to reaching meiotic commitment, cells exit meiosis and return to mitosis. Previous work has shown that cells commit to meiosis after prophase I but before entering the meiotic divisions. Since the Ndt80 transcription factor induces expression of middle meiosis genes necessary for the meiotic divisions, we examined the role of the NDT80 transcriptional network in meiotic commitment. Using a microfluidic approach to analyze single cells, we found that cells commit to meiosis in prometaphase I, after the induction of the Ndt80-dependent genes. Our results showed that high-level expression of NDT80 is important for the timing and irreversibility of meiotic commitment. A modest reduction in NDT80 levels delayed meiotic commitment based on meiotic stages, although the timing of each meiotic stage was similar to that of wildtype cells. A further reduction of NDT80 resulted in the surprising finding of inappropriately uncommitted cells: withdrawal of the meiosis-inducing signal and addition of the mitosis-inducing signal to cells at stages beyond metaphase I caused return to mitosis, leading to multi-nucleate cells. Since Ndt80 enhances its own transcription through positive feedback, we tested whether positive feedback ensured the irreversibility of meiotic commitment. Ablating positive feedback in NDT80 expression resulted in a complete loss of meiotic commitment. These findings suggest that irreversibility of meiotic commitment is a consequence of the NDT80 transcriptional positive feedback loop, which provides the high-level of Ndt80 required for the developmental switch of meiotic commitment. These results also illustrate the

  11. Preoperative oral use of Ibuprofen or dexamethasone may improve the anesthetic efficacy of an inferior alveolar nerve block in patients diagnosed with irreversible pulpitis.

    Science.gov (United States)

    Nusstein, John M

    2013-09-01

    Effect of premedication with ibuprofen and dexamethasone on success rate of inferior alveolar nerve block for teeth with asymptomatic irreversible pulpitis: a randomized clinical trial. Shahi S, Moktari H, Rahimi S, Yavari HR, Narimani S, Abdolrahmi M, Nezafati S. J Endod 2013;39(2):160-2. John M. Nusstein, DDS, MS PURPOSE/QUESTION: To determine whether preoperative oral administration of ibuprofen (400 mg), dexamethasone (0.5 mg), or placebo (lactose) would improve the anesthetic success rate of an inferior alveolar nerve block in patients with molars diagnosed with asymptomatic irreversible pulpitis University: Dental and Periodontal Research Center of Tabriz, Tabriz University of Medical Sciences, Tabriz, Iran Randomized controlled trial Level 2: Limited-quality, patient-oriented evidence Not applicable. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Dimensional Stability of Color-Changing Irreversible Hydrocolloids after Disinfection

    Directory of Open Access Journals (Sweden)

    Khaledi AAR

    2015-03-01

    Full Text Available Statement of Problem: Disinfection of dental impressions is a weak point in the dental hygiene chain. In addition, dental office personnel and dental technicians are endangered by cross-contamination. Objectives: This study aimed to investigate the dimensional stability of two color-changing irreversible hydrocolloid materials (IH after disinfection with glutaraldehyde. Materials and Methods: In this in vitro study, impressions were made of a master maxillary arch containing three reference inserts on the occlucal surface of the left and right maxillary second molars and in the incisal surface of the maxillary central incisors. Two types of color-changing irreversible hydrocolloid (tetrachrom, cavex were used. Glutaraldehyde 2% was used in two methods of spraying and immersion to disinfect the impressions. The control group was not disinfected. Casts were made of type IV gypsum. The linear dimensional change of the stone casts was measured with a profile projector. For statistical analysis, Kruskall-Wallis and Mann-Witney tests were used (α=0.05. Results: By immersion method, the casts fabricated from tetrachrom were 0.36% larger in the anteroposterior (AP and 0.05% smaller in cross arch (CA dimensions; however, the casts prepared after spraying of tetrachrom were 0.44% larger in the AP and 0.10% smaller in CA dimensions. The casts made from Cavex were 0.05% smaller in the AP and 0.02% smaller in CA dimensions after spraying and 0.01% smaller in the AP and 0.003% smaller in CA dimensions after immersion. Generally there were not significant differences in AP and CA dimensions of the experimental groups compared to the control (p > 0.05. Conclusions: Disinfection of the tested color-changing irreversible hydrocolloids by glutaraldahyde 2% did not compromise the accuracy of the obtained casts.

  13. Behavior of the irreversibility line in the new superconductor La1.5+xBa1.5+x-yCayCu3Oz

    International Nuclear Information System (INIS)

    Parra Vargas, C.A.; Pimentel, J.L.; Pureur, P.; Landínez Téllez, D.A.; Roa-Rojas, J.

    2012-01-01

    The irreversibility properties of high-T c superconductors are of major importance for technological applications. For example, a high irreversibility magnetic field is a more desirable quality for a superconductor . The irreversibility line in the H-T plane is constituted by experimental points, which divides the irreversible and reversible behavior of the magnetization. The irreversibility lines for series of La 1.5+x Ba 1.5+x-y Ca y Cu 3 O z polycrystalline samples with different doping were investigated. The samples were synthesized using the usual solid estate reaction method. Rietveld-type refinement of x-ray diffraction patterns permitted to determine the crystallization of material in a tetragonal structure. Curves of magnetization ZFC-FC for the system La 1.5+x Ba 1.5+x-y Ca y Cu 3 O z , were measured in magnetic fields of the 10-20,000 Oe, and allowed to obtain the values for the irreversibility and critical temperatures. The data of irreversibility temperature allowed demarcating the irreversibility line, T irr (H). Two main lines are used for the interpretation of the irreversibility line: one of those which suppose that the vortexes are activated thermally and the other proposes that associated to T irr a phase transition occurs. The irreversibility line is described by a power law. The obtained results allow concluding that in the system La 1.5+x Ba 1.5+x-y Ca y Cu 3 O z a characteristic bend of the Almeida-Thouless (AT) tendency is dominant for low fields and a bend Gabay-Toulouse (GT) behavior for high magnetic fields. This feature of the irreversibility line has been reported as a characteristic of granular superconductors and it corroborates the topological effects of vortexes mentioned by several authors .

  14. Irreversibility of a bad start: early exposure to osmotic stress limits growth and adaptive developmental plasticity.

    Science.gov (United States)

    Wu, Chi-Shiun; Gomez-Mestre, Ivan; Kam, Yeong-Choy

    2012-05-01

    Harsh environments experienced early in development have immediate effects and potentially long-lasting consequences throughout ontogeny. We examined how salinity fluctuations affected survival, growth and development of Fejervarya limnocharis tadpoles. Specifically, we tested whether initial salinity effects on growth and rates of development were reversible and whether they affected the tadpoles' ability to adaptively accelerate development in response to deteriorating conditions later in development. Tadpoles were initially assigned to either low or high salinity, and then some were switched between salinity levels upon reaching either Gosner stage 30 (early switch) or 38 (late switch). All tadpoles initially experiencing low salinity survived whereas those initially experiencing high salinity had poor survival, even if switched to low salinity. Growth and developmental rates of tadpoles initially assigned to high salinity did not increase after osmotic stress release. Initial low salinity conditions allowed tadpoles to attain a fast pace of development even if exposed to high salinity afterwards. Tadpoles experiencing high salinity only late in development metamorphosed faster and at a smaller size, indicating an adaptive acceleration of development to avoid osmotic stress. Nonetheless, early exposure to high salinity precluded adaptive acceleration of development, always causing delayed metamorphosis relative to those in initially low salinity. Our results thus show that stressful environments experienced early in development can critically impact life history traits, having long-lasting or irreversible effects, and restricting their ability to produce adaptive plastic responses.

  15. Magnetic irreversibility in granular superconductors: ac susceptibility study

    International Nuclear Information System (INIS)

    Perez, F.; Obradors, X.; Fontcuberta, J.; Vallet, M.; Gonzalez-Calbet, J.

    1991-01-01

    Ac susceptibility measurements of a ceramic weak-coupled superconductor in very low ac fields (2mG, 111Hz) are reported. We present evidence for the observation of the magnetic irreversibility following a ZFC-FC thermal cycling by means of ac susceptibilty measurements. It is shown that this technique also reflect local magnetic field effects in granular superconductors, as previously suggested in microwave surface resistance and I-V characteristics. (orig.)

  16. Irreversible dilation of NaCl contaminated lime-cement mortar due to crystallization cycles

    International Nuclear Information System (INIS)

    Lubelli, B.; Hees, R.P.J. van; Huinink, H.P.; Groot, C.J.W.P.

    2006-01-01

    The mechanism of damage occurring in NaCl contaminated materials has not been clarified yet. Apart from crystallization pressure, other hypotheses have been proposed to explain the cause of decay. Irreversible dilation has been observed in a few cases but has never been studied in a more systematic way. The aim of the research is to contribute to the modeling of this phenomenon. In the present paper the effect of NaCl on the hydric and hygric behavior of a lime-cement mortar is extensively studied. The results indicate that NaCl influences the hydric and hygric dilation behavior of the material. The material contaminated with NaCl shrinks during dissolution and dilates during crystallization of the salt. This dilation is irreversible and sufficient to damage the material after few dissolution/crystallization cycles. This behavior is not restricted to NaCl, but is observed in the presence of other salts as well (NaNO 3 and KCl). Outcomes of electron microscopy studies suggest that salts causing irreversible dilation tend to crystallize as layers on the pore wall

  17. Preparation of ultra-fine calcium carbonate by a solvent-free reaction using supersonic airflow and low temperatures

    OpenAIRE

    Cai, Yan-Hua; Ma, Dong-Mei; Peng, Ru-Fang; Chu, Shi-Jin

    2008-01-01

    The treatment of calcium chloride with sodium carbonate under solvent-free conditions with a supersonic airflow and at a low heating temperature leads to the synthesis of ultra-fine calcium carbonate. The reaction not only involves mild conditions, a simple operation, and high yields but also gives a high conversion rate.

  18. Unifying principles of irreversibility minimization for efficiency maximization in steady-flow chemically-reactive engines

    International Nuclear Information System (INIS)

    Ramakrishnan, Sankaran; Edwards, Christopher F.

    2014-01-01

    Systems research has led to the conception and development of various steady-flow, chemically-reactive, engine cycles for stationary power generation and propulsion. However, the question that remains unanswered is: What is the maximum-efficiency steady-flow chemically-reactive engine architecture permitted by physics? On the one hand the search for higher-efficiency cycles continues, often involving newer processes and devices (fuel cells, carbon separation, etc.); on the other hand the design parameters for existing cycles are continually optimized in response to improvements in device engineering. In this paper we establish that any variation in engine architecture—parametric change or process-sequence change—contributes to an efficiency increase via one of only two possible ways to minimize total irreversibility. These two principles help us unify our understanding from a large number of parametric analyses and cycle-optimization studies for any steady-flow chemically-reactive engine, and set a framework to systematically identify maximum-efficiency engine architectures. - Highlights: • A unified thermodynamic model to study chemically-reactive engine architectures is developed. • All parametric analyses of efficiency are unified by two irreversibility-minimization principles. • Variations in internal energy transfers yield a net work increase that is greater than engine irreversibility reduced. • Variations in external energy transfers yield a net work increase that is lesser than engine irreversibility reduced

  19. Antibacterial efficacy and effect of Morinda citrifolia L. mixed with irreversible hydrocolloid for dental impressions: A randomized controlled trial.

    Science.gov (United States)

    Ahmed, A Shafath; Charles, P David; Cholan, R; Russia, M; Surya, R; Jailance, L

    2015-08-01

    This study aimed to evaluate whether the extract of Morinda citrifolia L. mixed with irreversible hydrocolloid powder decreases microbial contamination during impression making without affecting the resulting casts. Twenty volunteers were randomly divided into two groups (n = 10). Group A 30 ml extract of M. citrifolia L diluted in 30 ml of water was mixed to make the impression with irreversible hydrocolloid material. Group B 30 ml deionized water was mixed with irreversible hydrocolloid material to make the impressions following which the surface roughness and dimensional stability of casts were evaluated. Extract of M. citrifolia L. mixed with irreversible hydrocolloid decreased the percentage of microorganisms when compared with water (P impression quality.

  20. Phase control of light amplification with dynamically irreversible pathways of population transfer in a Λ system

    International Nuclear Information System (INIS)

    Yuan Shi; Wu Jinhui; Gao Jinyue; Pan Chunliu

    2002-01-01

    We use the relative phase of two coherent fields for the control of light amplification with dynamically irreversible pathways of population transfer in a Λ system. The population inversion and gain with dynamically irreversible pathways of population transfer are shown as the relative phase is varied. We support our results by numerical calculation and analytical explanation

  1. Logic reversibility and thermodynamic irreversibility demonstrated by DNAzyme-based Toffoli and Fredkin logic gates.

    Science.gov (United States)

    Orbach, Ron; Remacle, Françoise; Levine, R D; Willner, Itamar

    2012-12-26

    The Toffoli and Fredkin gates were suggested as a means to exhibit logic reversibility and thereby reduce energy dissipation associated with logic operations in dense computing circuits. We present a construction of the logically reversible Toffoli and Fredkin gates by implementing a library of predesigned Mg(2+)-dependent DNAzymes and their respective substrates. Although the logical reversibility, for which each set of inputs uniquely correlates to a set of outputs, is demonstrated, the systems manifest thermodynamic irreversibility originating from two quite distinct and nonrelated phenomena. (i) The physical readout of the gates is by fluorescence that depletes the population of the final state of the machine. This irreversible, heat-releasing process is needed for the generation of the output. (ii) The DNAzyme-powered logic gates are made to operate at a finite rate by invoking downhill energy-releasing processes. Even though the three bits of Toffoli's and Fredkin's logically reversible gates manifest thermodynamic irreversibility, we suggest that these gates could have important practical implication in future nanomedicine.

  2. Unified approach to the study of solid fuel combustion characteristics at high airflow speeds

    Science.gov (United States)

    Vnuchkov, D. A.; Lukashevich, S. V.; Nalivaychenko, D. G.; Zvegintsev, V. I.

    2017-10-01

    The main objective of the research is the development of guidelines for a unified approach to testing the combustion of different solid fuels in gaseous oxidant high-speed flow, so that research outcomes could be presented in a standardized and cohesive form. All the experiments were performed on a special experimental installation designed for quantification of the burning characteristics of different fuels in a wide range of the airflow parameters at the same geometry of the combustion chamber.

  3. Extended irreversible thermodynamics and non-equilibrium temperature

    Directory of Open Access Journals (Sweden)

    Casas-Vazquez, Jose'

    2008-02-01

    Full Text Available We briefly review the concept of non-equilibrium temperature from the perspectives of extended irreversible thermodynamics, fluctuation theory, and statistical mechanics. The relations between different proposals are explicitly examined in two especially simple systems: an ideal gas in steady shear flow and a forced harmonic oscillator in a thermal bath. We examine with special detail temperatures related to the average molecular kinetic energy along different spatial directions, to the average configurational energy, to the derivative of the entropy with respect to internal energy, to fluctuation-dissipation relation and discuss their measurement.

  4. Transition from reversible to irreversible magnetic exchange-spring processes in antiferromagnetically exchange-coupled hard/soft/hard trilayer structures

    International Nuclear Information System (INIS)

    Wang Xiguang; Guo Guanghua; Zhang Guangfu

    2011-01-01

    The demagnetization processes of antiferromagnetically exchange-coupled hard/soft/hard trilayer structures have been studied based on the discrete one-dimensional atomic chain model and the linear partial domain-wall model. It is found that, when the magnetic anisotropy of soft layer is taken into account, the changes of the soft layer thickness and the interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible magnetic exchange-spring process. For the trilayer structures with very thin soft layer, the demagnetization process exhibits typical reversible exchange-spring behavior. However, as the thickness of soft layer is increased, there is a crossover point t c , after which the process becomes irreversible. Similarly, there is also a critical interfacial exchange coupling constant A sh c , above which the exchange-spring process is reversible. When A sh sh c , the irreversible exchange-spring process is achieved. The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling A sh and soft layer thickness N s . - Research highlights: → A differing magnetic exchange-spring process is found in antiferromagnetically exchange-coupled hard/soft/hard trilayers if the magnetic anisotropy of the soft layers is taken into account. → The change of the soft layer thickness may lead to a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The change of the soft-hard interfacial exchange coupling strength may lead a transition of demagnetization process in soft layer from the reversible to the irreversible exchange-spring process. → The phase diagram of reversible and irreversible exchange-spring processes is mapped in the plane of the interfacial exchange coupling and soft layer thickness.

  5. Canonical Structure and Orthogonality of Forces and Currents in Irreversible Markov Chains

    Science.gov (United States)

    Kaiser, Marcus; Jack, Robert L.; Zimmer, Johannes

    2018-03-01

    We discuss a canonical structure that provides a unifying description of dynamical large deviations for irreversible finite state Markov chains (continuous time), Onsager theory, and Macroscopic Fluctuation Theory (MFT). For Markov chains, this theory involves a non-linear relation between probability currents and their conjugate forces. Within this framework, we show how the forces can be split into two components, which are orthogonal to each other, in a generalised sense. This splitting allows a decomposition of the pathwise rate function into three terms, which have physical interpretations in terms of dissipation and convergence to equilibrium. Similar decompositions hold for rate functions at level 2 and level 2.5. These results clarify how bounds on entropy production and fluctuation theorems emerge from the underlying dynamical rules. We discuss how these results for Markov chains are related to similar structures within MFT, which describes hydrodynamic limits of such microscopic models.

  6. Understanding Irreversible Degradation of Nb3Sn Wires with Fundamental Fracture Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Yuhu [PPPL; Calzolaio, Ciro [Univ of Geneva; Senatore, Carmine [Univ of Geneva

    2014-08-01

    Irreversible performance degradation of advanced Nb3Sn superconducting wires subjected to transverse or axial mechanical loading is a critical issue for the design of large-scale fusion and accelerator magnets such as ITER and LHC. Recent SULTAN tests indicate that most cable-in-conduit conductors for ITER coils made of Nb3Sn wires processed by various fabrication techniques show similar performance degradation under cyclic loading. The irreversible degradation due to filament fracture and local strain accumulation in Nb3Sn wires cannot be described by the existing strand scaling law. Fracture mechanic modeling combined with X-ray diffraction imaging of filament micro-crack formation inside the wires under mechanical loading may reveal exciting insights to the wire degradation mechanisms. We apply fundamental fracture mechanics with a singularity approach to study influence of wire filament microstructure of initial void size and distribution to local stress concentration and potential crack propagation. We report impact of the scale and density of the void structure on stress concentration in the composite wire materials for crack initiation. These initial defects result in an irreversible degradation of the critical current beyond certain applied stress. We also discuss options to minimize stress concentration in the design of the material microstructure for enhanced wire performance for future applications.

  7. Aging effects on airflow dynamics and lung function in human bronchioles.

    Science.gov (United States)

    Kim, JongWon; Heise, Rebecca L; Reynolds, Angela M; Pidaparti, Ramana M

    2017-01-01

    The mortality rate for patients requiring mechanical ventilation is about 35% and this rate increases to about 53% for the elderly. In general, with increasing age, the dynamic lung function and respiratory mechanics are compromised, and several experiments are being conducted to estimate these changes and understand the underlying mechanisms to better treat elderly patients. Human tracheobronchial (G1 ~ G9), bronchioles (G10 ~ G22) and alveolar sacs (G23) geometric models were developed based on reported anatomical dimensions for a 50 and an 80-year-old subject. The aged model was developed by altering the geometry and material properties of the model developed for the 50-year-old. Computational simulations using coupled fluid-solid analysis were performed for geometric models of bronchioles and alveolar sacs under mechanical ventilation to estimate the airflow and lung function characteristics. The airway mechanical characteristics decreased with aging, specifically a 38% pressure drop was observed for the 80-year-old as compared to the 50-year-old. The shear stress on airway walls increased with aging and the highest shear stress was observed in the 80-year-old during inhalation. A 50% increase in peak strain was observed for the 80-year-old as compared to the 50-year-old during exhalation. The simulation results indicate that there is a 41% increase in lung compliance and a 35%-50% change in airway mechanical characteristics for the 80-year-old in comparison to the 50-year-old. Overall, the airway mechanical characteristics as well as lung function are compromised due to aging. Our study demonstrates and quantifies the effects of aging on the airflow dynamics and lung capacity. These changes in the aging lung are important considerations for mechanical ventilation parameters in elderly patients. Realistic geometry and material properties need to be included in the computational models in future studies.

  8. Influence of input data on airflow network accuracy in residential buildings with natural wind- and stack-driven ventilation

    Institute of Scientific and Technical Information of China (English)

    Krzysztof Arendt; Marek Krzaczek; Jacek Tejchman

    2017-01-01

    The airflow network (AFN) modeling approach provides an attractive balance between the accuracy and computational demand for naturally ventilated buildings. Its accuracy depends on input parameters such as wind pressure and opening discharge coefficients. In most cases, these parameters are obtained from secondary sources which are solely representative for very simplified buildings, i.e. for buildings without facade details. Although studies comparing wind pressure coefficients or discharge coefficients from different sources exist, the knowledge regarding the effect of input data on AFN is still poor. In this paper, the influence of wind pressure data on the accuracy of a coupled AFN-BES model for a real building with natural wind- and stack-driven ventilation was analyzed. The results of 8 computation cases with different wind pressure data from secondary sources were compared with the measured data. Both the indoor temperatures and the airflow were taken into account. The outcomes indicated that the source of wind pressure data had a significant influence on the model performance.

  9. A modeling study of the effect of gravity on airflow distribution and particle deposition in the lung.

    Science.gov (United States)

    Asgharian, Bahman; Price, Owen; Oberdörster, Gunter

    2006-06-01

    Inhalation of particles generated as a result of thermal degradation from fire or smoke, as may occur on spacecraft, is of major health concern to space-faring countries. Knowledge of lung airflow and particle transport under different gravity environments is required to addresses this concern by providing information on particle deposition. Gravity affects deposition of particles in the lung in two ways. First, the airflow distribution among airways is changed in different gravity environments. Second, particle losses by sedimentation are enhanced with increasing gravity. In this study, a model of airflow distribution in the lung that accounts for the influence of gravity was used for a mathematical description of particle deposition in the human lung to calculate lobar, regional, and local deposition of particles in different gravity environments. The lung geometry used in the mathematical model contained five lobes that allowed the assessment of lobar ventilation distribution and variation of particle deposition. At zero gravity, it was predicted that all lobes of the lung expanded and contracted uniformly, independent of body position. Increased gravity in the upright position increased the expansion of the upper lobes and decreased expansion of the lower lobes. Despite a slight increase in predicted deposition of ultrafine particles in the upper lobes with decreasing gravity, deposition of ultrafine particles was generally predicted to be unaffected by gravity. Increased gravity increased predicted deposition of fine and coarse particles in the tracheobronchial region, but that led to a reduction or even elimination of deposition in the alveolar region for coarse particles. The results from this study show that existing mathematical models of particle deposition at 1 G can be extended to different gravity environments by simply correcting for a gravity constant. Controlled studies in astronauts on future space missions are needed to validate these predictions.

  10. Mobile ultra-clean unidirectional airflow screen reduces air contamination in a simulated setting for intra-vitreal injection.

    Science.gov (United States)

    Lapid-Gortzak, Ruth; Traversari, Roberto; van der Linden, Jan Willem; Lesnik Oberstein, Sarit Y; Lapid, Oren; Schlingemann, Reinier O

    2017-02-01

    The aim of this study is to determine whether the use of a mobile ultra-clean laminar airflow screen reduces the air-borne particle counts in the setting of a simulated procedure of an intra-vitreal injection. A mobile ultra-clean unidirectional airflow (UDF) screen was tested in a simulated procedure for intra-vitreal injections in a treatment room without mechanical ventilation. One UDF was passed over the instrument tray and the surgical area. The concentration of particles was measured in the background, over the instrument table, and next to the ocular area. The degree of protection was calculated at the instrument table and at the surgical site. Use of the UDF mobile screen reduced the mean particle concentration (particles > 0.3 microns) on the instrument table by a factor of at least 100.000 (p air contamination. Mobile UDF screen reduces the mean particle concentration substantially. The mobile UDF screen may therefore allow for a safer procedural environment for ambulatory care procedures such as intra-vitreal injections in treatment rooms.

  11. Morphological measurements in computed tomography correlate with airflow obstruction in chronic obstructive pulmonary disease : systematic review and meta-analysis

    NARCIS (Netherlands)

    Xie, X.Q.; de Jong, P.A.; Oudkerk, M.; Wang, Y.; ten Hacken, N.H.T.; Miao, J.T.; Zhang, GuiXiang; de Bock, G.H.; Vliegenthart, R.

    2012-01-01

    To determine the correlation between CT measurements of emphysema or peripheral airways and airflow obstruction in chronic obstructive pulmonary disease (COPD). PubMed, Embase and Web of Knowledge were searched from 1976 to 2011. Two reviewers independently screened 1,763 citations to identify

  12. Irreversibility analysis for optimization design of plate fin heat exchangers using a multi-objective cuckoo search algorithm

    International Nuclear Information System (INIS)

    Wang, Zhe; Li, Yanzhong

    2015-01-01

    Highlights: • The first application of IMOCS for plate-fin heat exchanger design. • Irreversibility degrees of heat transfer and fluid friction are minimized. • Trade-off of efficiency, total cost and pumping power is achieved. • Both EGM and EDM methods have been compared in the optimization of PFHE. • This study has superiority over other single-objective optimization design. - Abstract: This paper introduces and applies an improved multi-objective cuckoo search (IMOCS) algorithm, a novel met-heuristic optimization algorithm based on cuckoo breeding behavior, for the multi-objective optimization design of plate-fin heat exchangers (PFHEs). A modified irreversibility degree of the PFHE is separated into heat transfer and fluid friction irreversibility degrees which are adopted as two initial objective functions to be minimized simultaneously for narrowing the search scope of the design. The maximization efficiency, minimization of pumping power, and total annual cost are considered final objective functions. Results obtained from a two dimensional normalized Pareto-optimal frontier clearly demonstrate the trade-off between heat transfer and fluid friction irreversibility. Moreover, a three dimensional Pareto-optimal frontier reveals a relationship between efficiency, total annual cost, and pumping power in the PFHE design. Three examples presented here further demonstrate that the presented method is able to obtain optimum solutions with higher accuracy, lower irreversibility, and fewer iterations as compared to the previous methods and single-objective design approaches

  13. Anesthetic efficacy of articaine for inferior alveolar nerve blocks in patients with symptomatic versus asymptomatic irreversible pulpitis.

    Science.gov (United States)

    Argueta-Figueroa, Liliana; Arzate-Sosa, Gabriel; Mendieta-Zeron, Hugo

    2012-01-01

    This study sought to determine the anesthetic efficacy of 4% articaine with 1:100,000 epinephrine in patients with symptomatic and asymptomatic irreversible pulpitis in mandibular posterior teeth and if individual patient factors, pulpal disease characteristics, and previous medication are correlated to local anesthetic success. A second objective was to determine the specificity and sensibility of a cold test for prediction of anesthetic success prior to endodontic treatment. Seventy patients diagnosed with irreversible pulpitis in mandibular posterior teeth received 1.6 mL of 4% articaine with 1:100,000 epinephrine for an inferior alveolar nerve block (IANB) using a metal guide. The anesthetic solution was injected with a computer-preprogrammed delivery system for local anesthesia. Endodontic access was begun 15 minutes after solution deposition; later, patients rated their discomfort using the visual analog scale (VAS). The success rate for the IA NB using articaine was 64.2% in patients with symptomatic irreversible pulpitis and 86.9% in patients with asymptomatic irreversible pulpitis. Cold test prior to root canal treatment had a specificity and sensibility of 12.5% and 87.1%, respectively. The anesthetic efficacy of articaine in irreversible pulpitis is moderately acceptable, and anesthetic success increases when the patient has been premedicated with NSAIDs. The cold test appears to be a favorable indicator for predicting anesthetic success.

  14. Lagrangian formulation of irreversible thermodynamics and the second law of thermodynamics.

    Science.gov (United States)

    Glavatskiy, K S

    2015-05-28

    We show that the equations which describe irreversible evolution of a system can be derived from a variational principle. We suggest a Lagrangian, which depends on the properties of the normal and the so-called "mirror-image" system. The Lagrangian is symmetric in time and therefore compatible with microscopic reversibility. The evolution equations in the normal and mirror-imaged systems are decoupled and describe therefore independent irreversible evolution of each of the systems. The second law of thermodynamics follows from a symmetry of the Lagrangian. Entropy increase in the normal system is balanced by the entropy decrease in the mirror-image system, such that there exists an "integral of evolution" which is a constant. The derivation relies on the property of local equilibrium, which states that the local relations between the thermodynamic quantities in non-equilibrium are the same as in equilibrium.

  15. Effect of airflow on biodrying of gardening wastes in reactors.

    Science.gov (United States)

    Colomer-Mendoza, F J; Herrera-Prats, L; Robles-Martínez, F; Gallardo-Izquierdo, A; Piña-Guzmán, A B

    2013-05-01

    Biodrying consists of reducing moisture by using the heat from aerobic bio-degradation. The parameters that control the process are: aeration, temperature during the process, initial moisture of biowaste, and temperature and relative humidity of the input air. Lawn mowing and garden waste from the gardens of the University Jaume I, Castellón (Spain) were used as a substrate. Biodrying was performed in 10 reactors with known air volumes from 0.88 to 6.42 L/(min x kg dry weight). To promote aeration, 5 of the reactors had 15% of a bulking agent added. The experiment lasted 20 days. After the experiments it was found that the bulking agent led to greater weight loss. However, the increased airflow rate was not linearly proportional to the weight loss.

  16. The analysis of irreversibility, uncertainty and dynamic technical inefficiency on the investment decision in the Spanish olive sector

    NARCIS (Netherlands)

    Lambarraa, Fatima; Stefanou, Spiro; Gil, José M.

    2016-01-01

    This study addresses irreversible investment decision-making in the context of uncertainty when allowing for inefficiency to be transmitted over time. Both irreversibility and persistence in technical inefficiency can lead to sluggish adjustment of quasi-fixed factors of production. The context

  17. Revisiting the Glansdorff–Prigogine criterion for stability within irreversible thermodynamics

    Czech Academy of Sciences Publication Activity Database

    Maes, C.; Netočný, Karel

    2015-01-01

    Roč. 159, č. 6 (2015), s. 1286-1299 ISSN 0022-4715 R&D Projects: GA ČR GAP204/12/0897 Institutional support: RVO:68378271 Keywords : irreversible processes * thermodynamic stability * excess entropy production * nonequilibrium free energy * Clausius heat theorem Subject RIV: BE - Theoretical Physics Impact factor: 1.537, year: 2015

  18. Numerical simulations of island-scale airflow over Maui and the Maui vortex under summer trade wind conditions

    Science.gov (United States)

    DaNa L. Carlis; Yi-Leng Chen; Vernon R. Morris

    2010-01-01

    The fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) coupled with the Noah land surface model (LSM) is employed to simulate island-scale airflow and circulations over Maui County, Hawaii, under summer trade wind conditions, during July–August 2005. The model forecasts are validated by surface observations with good agreement.

  19. Lattice animals in diffusion limited binary colloidal system

    Science.gov (United States)

    Shireen, Zakiya; Babu, Sujin B.

    2017-08-01

    In a soft matter system, controlling the structure of the amorphous materials has been a key challenge. In this work, we have modeled irreversible diffusion limited cluster aggregation of binary colloids, which serves as a model for chemical gels. Irreversible aggregation of binary colloidal particles leads to the formation of a percolating cluster of one species or both species which are also called bigels. Before the formation of the percolating cluster, the system forms a self-similar structure defined by a fractal dimension. For a one component system when the volume fraction is very small, the clusters are far apart from each other and the system has a fractal dimension of 1.8. Contrary to this, we will show that for the binary system, we observe the presence of lattice animals which has a fractal dimension of 2 irrespective of the volume fraction. When the clusters start inter-penetrating, we observe a fractal dimension of 2.5, which is the same as in the case of the one component system. We were also able to predict the formation of bigels using a simple inequality relation. We have also shown that the growth of clusters follows the kinetic equations introduced by Smoluchowski for diffusion limited cluster aggregation. We will also show that the chemical distance of a cluster in the flocculation regime will follow the same scaling law as predicted for the lattice animals. Further, we will also show that irreversible binary aggregation comes under the universality class of the percolation theory.

  20. Quantum degeneracy effect on performance of irreversible Otto cycle with ideal Bose gas

    International Nuclear Information System (INIS)

    Wu Feng; Chen Lingen; Sun Fengrui; Wu Chih; Guo Fangzhong; Li Qing

    2006-01-01

    An Otto cycle working with an ideal Bose gas is called a Bose Otto cycle. The internal irreversibility of the cycle is included in the factors of internal irreversibility degree. The quantum degeneracy effect on the performance of the cycle is investigated based on quantum statistical mechanics and thermodynamics. Variations of the maximum work output ratio R W and the efficiency ratio y with temperature ratio τ are examined, which reveal the influence of the quantum degeneracy of the working substance on the performance of a Bose Otto cycle. It is shown that the results obtained herein are valid under both classical and quantum ideal gas conditions

  1. Evaluation of properties of irreversible hydrocolloid impression materials mixed with disinfectant liquids

    Directory of Open Access Journals (Sweden)

    Arul Amalan

    2013-01-01

    Conclusion: Chlorhexidine solution can be used to mix irreversible hydrocolloid impression materials in regular dental practice as it did not significantly alter the properties. This may ensure effective disinfection of impressions.

  2. Diurnal and seasonal variation in air exchange rates and interzonal airflows measured by active and passive tracer gas in homes

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Gustavsen, Sine; Frederiksen, Marie

    2016-01-01

    Outdoor air delivery to buildings is an important parameter in the assessment of pollutant exposure indoors. Detailed and well controlled measurements of air exchange rates (AER) and interzonal airflows in residential environment are scarce. We measured the outdoor AERs in up to six rooms in five...... rooms. Window opening behavior had a strong influence on AERs, which were highest during occupied daytime periods, lowest in the night; highest in the summer, lowest in the winter. Significant differences were found between AERs measured by the different techniques. The median nighttime AER in all...... studied the pollutant distribution from one room (source room) and interzonal airflows across the dwellings. The air within a given floor was well mixed, with the average tracer gas concentration in the non-source rooms reaching approximately 70% of the source room concentration. There was less air...

  3. Irreversibility in room temperature current–voltage characteristics of NiFe_2O_4 nanoparticles: A signature of electrical memory effect

    International Nuclear Information System (INIS)

    Dey, P.; Debnath, Rajesh; Singh, Swati; Mandal, S.K.; Roy, J.N.

    2017-01-01

    Room temperature I–V characteristics study, both in presence and absence of magnetic field (1800 Oe), has been performed on NiFe_2O_4 nanoparticles, having different particle size (φ~14, 21 and 31 nm). Our experiments on these nanoparticles provide evidences for: (1) electrical irreversibility or hysteretic behaviour; (2) positive magnetoresistance and (3) magnetic field dependent electrical irreversibility or hysteresis in the sample. “Hysteretic” nature of I–V curve reveals the existence of electrical memory effect in the sample. Significantly, such hysteresis has been found to be tuned by magnetic field. In order to explain the observed electrical irreversibility, we have proposed a phenomenological model on the light of induced polarization in the sample. Both the positive magnetoresistance and the observed magnetic field dependence of electrical irreversibility have been explained through magnetostriction phenomenon. Interestingly, such effects are found to get reduced with increasing particle size. For NiFe_2O_4 nanoparticles having φ=31 nm, we did not observe any irreversibility effect. This feature has been attributed to the enhanced grain surface effect that in turn gives rise to the residual polarization and hence electrical memory effect in NiFe_2O_4 nanoparticles, having small nanoscopic particle size. - Highlights: • I-V characteristics study of NiFe_2O_4 nanoparticles with varying particle sizes. • Experiments evident electrical hysteretic behaviour, i.e., electrical memory effect. • Magnetic field dependent electrical irreversibility is due to magnetostriction. • A phenomenological model has been proposed on the light of induced polarization. • Such electrical irreversibility decreases with increasing particle sizes.

  4. Model for an irreversible bias current in the superconducting qubit measurement process

    International Nuclear Information System (INIS)

    Hutchinson, G. D.; Williams, D. A.; Holmes, C. A.; Stace, T. M.; Spiller, T. P.; Barrett, S. D.; Milburn, G. J.; Hasko, D. G.

    2006-01-01

    The superconducting charge-phase ''quantronium'' qubit is considered in order to develop a model for the measurement process used in the experiment of Vion et al. [Science 296, 886 (2002)]. For this model we propose a method for including the bias current in the readout process in a fundamentally irreversible way, which to first order is approximated by the Josephson junction tilted-washboard potential phenomenology. The decohering bias current is introduced in the form of a Lindblad operator and the Wigner function for the current-biased readout Josephson junction is derived and analyzed. During the readout current pulse used in the quantronium experiment we find that the coherence of the qubit initially prepared in a symmetric superposition state is lost at a time of 0.2 ns after the bias current pulse has been applied, a time scale that is much shorter than the experimental readout time. Additionally we look at the effect of Johnson-Nyquist noise with zero mean from the current source during the qubit manipulation and show that the decoherence due to the irreversible bias current description is an order of magnitude smaller than that found through adding noise to the reversible tilted-washboard potential model. Our irreversible bias current model is also applicable to persistent-current-based qubits where the state is measured according to its flux via a small-inductance direct-current superconducting quantum interference device

  5. Experimental investigation of nasal airflow.

    Science.gov (United States)

    Doorly, D; Taylor, D J; Franke, P; Schroter, R C

    2008-05-01

    The airway geometry of the nasal cavity is manifestly complex, and the manner in which it controls the airflow to accomplish its various physiological functions is not fully understood. Since the complex morphology and inaccessibility of the nasal passageways precludes detailed in-vivo measurements, either computational simulation or in-vitro experiments are needed to determine how anatomical form and function are related. The fabrication of a replica model of the nasal cavity, of a high optical clarity and derived from in-vivo scan data is described here, together with characteristics of the flow field investigated using particle image velocimetry (PIV) and flow visualization. Flow visualization is shown to be a capable and convenient technique for identifying key phenomena. Specifically the emergence of the jet from the internal nasal valve into the main cavity, how it impacts on the middle turbinate, and the large enhancement of dispersion that accompanies the initial appearance of flow instability are revealed as particularly significant features. The findings from the visualization experiments are complemented by PIV imaging, which provides quantitative detail on the variations in velocity in different regions of the nasal cavity. These results demonstrate the effectiveness of the cavity geometry in partitioning the flow into high shear zones, which facilitate rapid heat transfer and humidification from the nasal mucosa, and slower zones affording greater residence times to facilitate olfactory sensing. The experimental results not only provide a basis for comparison with other computational modelling but also demonstrate an alternative and flexible means to investigate complex flows, relevant to studies in different parts of the respiratory or cardiovascular systems.

  6. Modeling airflow and particle transport/deposition in pulmonary airways.

    Science.gov (United States)

    Kleinstreuer, Clement; Zhang, Zhe; Li, Zheng

    2008-11-30

    A review of research papers is presented, pertinent to computer modeling of airflow as well as nano- and micron-size particle deposition in pulmonary airway replicas. The key modeling steps are outlined, including construction of suitable airway geometries, mathematical description of the air-particle transport phenomena and computer simulation of micron and nanoparticle depositions. Specifically, diffusion-dominated nanomaterial deposits on airway surfaces much more uniformly than micron particles of the same material. This may imply different toxicity effects. Due to impaction and secondary flows, micron particles tend to accumulate around the carinal ridges and to form "hot spots", i.e., locally high concentrations which may lead to tumor developments. Inhaled particles in the size range of 20nm< or =dp< or =3microm may readily reach the deeper lung region. Concerning inhaled therapeutic particles, optimal parameters for mechanical drug-aerosol targeting of predetermined lung areas can be computed, given representative pulmonary airways.

  7. Fuel starvation. Irreversible degradation mechanisms in PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Rangel, Carmen M.; Silva, R.A.; Travassos, M.A.; Paiva, T.I.; Fernandes, V.R. [LNEG, National Laboratory for Energy and Geology, Lisboa (Portugal). UPCH Fuel Cells and Hydrogen Unit

    2010-07-01

    PEM fuel cell operates under very aggressive conditions in both anode and cathode. Failure modes and mechanism in PEM fuel cells include those related to thermal, chemical or mechanical issues that may constrain stability, power and lifetime. In this work, the case of fuel starvation is examined. The anode potential may rise to levels compatible with the oxidization of water. If water is not available, oxidation of the carbon support will accelerate catalyst sintering. Diagnostics methods used for in-situ and ex-situ analysis of PEM fuel cells are selected in order to better categorize irreversible changes of the cell. Electrochemical Impedance Spectroscopy (EIS) is found instrumental in the identification of fuel cell flooding conditions and membrane dehydration associated to mass transport limitations / reactant starvation and protonic conductivity decrease, respectively. Furthermore, it indicates that water electrolysis might happen at the anode. Cross sections of the membrane catalyst and gas diffusion layers examined by scanning electron microscopy indicate electrode thickness reduction as a result of reactions taking place during hydrogen starvation. Catalyst particles are found to migrate outwards and located on carbon backings. Membrane degradation in fuel cell environment is analyzed in terms of the mechanism for fluoride release which is considered an early predictor of membrane degradation. (orig.)

  8. A study on new method of noninvasive esophageal venous pressure measurement based on the airflow and laser detection technology.

    Science.gov (United States)

    Hu, Chenghuan; Huang, Feizhou; Zhang, Rui; Zhu, Shaihong; Nie, Wanpin; Liu, Xunyang; Liu, Yinglong; Li, Peng

    2015-01-01

    Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

  9. Synergetcs - a field beyond irreversible thermodynamics

    International Nuclear Information System (INIS)

    Haken, H.

    1978-01-01

    This lecture introduces the reader to synergetics, a very young field of interdisciplinary research, which is devoted to the question of self-organization and, quite generally, to the birth of new qualities. After comparing the role of thermodynamics, irreversible thermodynamics and synergetics in the description of phenomena we give a few examples for self-oragnizing systems. Next we outline the mathematical approach and consider the generalized Ginzburg-Landau equations for non equilibrium phase transitions. We continue by applying these equations to the problem of morphogenesis in biology. We close our lecture by extending the formalism to spatially inhomogeneous or oscillating systems and arrive at order-parameter equations which are capable of describing new large classes of higher bifurcation schemes. (HJ)

  10. Capital dissipation minimization for a class of complex irreversible resource exchange processes

    Science.gov (United States)

    Xia, Shaojun; Chen, Lingen

    2017-05-01

    A model of a class of irreversible resource exchange processes (REPes) between a firm and a producer with commodity flow leakage from the producer to a competitive market is established in this paper. The REPes are assumed to obey the linear commodity transfer law (LCTL). Optimal price paths for capital dissipation minimization (CDM) (it can measure economic process irreversibility) are obtained. The averaged optimal control theory is used. The optimal REP strategy is also compared with other strategies, such as constant-firm-price operation and constant-commodity-flow operation, and effects of the amount of commodity transferred and the commodity flow leakage on the optimal REP strategy are also analyzed. The commodity prices of both the producer and the firm for the CDM of the REPes with commodity flow leakage change with the time exponentially.

  11. Irreversible thermodynamics of dark energy on the entropy-corrected apparent horizon

    Energy Technology Data Exchange (ETDEWEB)

    Karami, K; Sahraei, N [Department of Physics, University of Kurdistan, Pasdaran Street, Sanandaj (Iran, Islamic Republic of); Jamil, M, E-mail: KKarami@uok.ac.i, E-mail: mjamil@camp.nust.edu.p [Center for Advanced Mathematics and Physics (CAMP), National University of Sciences and Technology (NUST), Islamabad (Pakistan)

    2010-10-15

    We study the irreversible (non-equilibrium) thermodynamics of the Friedmann-Robertson-Walker (FRW) universe containing only dark energy. Using the modified entropy-area relation that is motivated by loop quantum gravity, we calculate the entropy-corrected form of the apparent horizon of the FRW universe.

  12. Pulpitis irreversible como forma de presentación de un odontoma

    OpenAIRE

    Berástegui, Esther; Buenechea Imaz, Ramón

    1997-01-01

    Se presenta un caso de odontoma compuesto que provocó pulpitis irreversible en el incisivo central superior derecho (1,1) en una joven de 20 años. El tratamiento fue la biopulpectomía total y extirpación quirúrgica del tumor.

  13. Optimized damper control of pressure and airflow in ventilation systems

    DEFF Research Database (Denmark)

    Koulani, Chrysanthi Sofia; Hviid, Christian Anker; Terkildsen, Søren

    2014-01-01

    Conventional control strategies in variable air volume (VAV) ventilation systems do not take fully into advantage the potential energy savings since the system operation is based on maintaining a constant static pressure (CSP) set point in the main duct irrespective of the actual pressure demand...... by using the Simulink programming tool which is addon software to MATLAB mathematical programming language. A model of a VAV ventilation system was created in Simulink based on the International Building Physics Toolbox (IBPT); the IBPT thermal zone was remodelled in order to calculate dynamically...... the airflow demand according to the zone air temperature. The performance of the Simulink model was evaluated based on the experimental setup of the ventilation system. The SPR control method established stable system operation and was proven efficient to maintain comfortable space conditions while reducing...

  14. Three distinct surgical clothing systems in a turbulent mixing operating room equipped with mobile ultraclean laminar airflow screen

    DEFF Research Database (Denmark)

    Sadrizadeh, Sasan; Holmberg, Sture; Nielsen, Peter Vilhelm

    2016-01-01

    on the operating and instrument tables with and without the additional mobile airflow screen. Three different source strengths (the mean bacteria-carrying particle value emitted from one person per second) due to staff clothing variety were considered. Model validation was performed through result comparisons...... a clothing system with high protective capacity reduced particle concentration....

  15. Comparison between mixed and laminar airflow systems in operating rooms and the influence of human factors: experiences from a Swedish orthopedic center.

    Science.gov (United States)

    Erichsen Andersson, Annette; Petzold, Max; Bergh, Ingrid; Karlsson, Jón; Eriksson, Bengt I; Nilsson, Kerstin

    2014-06-01

    The importance of laminar airflow systems in operating rooms as protection from surgical site infections has been questioned. The aim of our study was to explore the differences in air contamination rates between displacement ventilation and laminar airflow systems during planned and acute orthopedic implant surgery. A second aim was to compare the influence of the number of people present, the reasons for traffic flow, and the door-opening rates between the 2 systems. Active air sampling and observations were made during 63 orthopedic implant operations. The laminar airflow system resulted in a reduction of 89% in colony forming units in comparison with the displacement system (P operating rooms offer high-quality air during surgery, with very low levels of colony forming units close to the surgical wound. The continuous maintenance of laminar air flow and other technical systems are crucial, because minor failures in complex systems like those in operating rooms can result in a detrimental effect on air quality and jeopardize the safety of patients. The technical ventilation solutions are important, but they do not guarantee clean air, because many other factors, such as the organization of the work and staff behavior, influence air cleanliness. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  16. ESTIMATION OF IRREVERSIBLE DAMAGEABILITY AT FATIGUE OF CARBON STEEL

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2014-04-01

    Full Text Available Purpose. Damageability estimation of carbon steel in the conditions of cyclic loading. Methodology. The steel fragments of railway wheel rim and rail head served as material for research with chemical composition 0.65 % С, 0.67 % Mn, 0.3 % Si, 0.027 % P, 0.028 % S и 0.7 % C, 0.82 % Mn, 0.56 % Si, 0.025 % P, 0.029 % S accordingly. The microstructure of tested steels corresponded to the state of metal after a hot plastic deformation. The fatigue research was conducted in the conditions of symmetric bend using the proof-of-concept machine of type «Saturn-10». Full Wohler diagrams and the lines corresponding to forming of sub-and micro cracks were constructed. The distribution analysis of internal stresses in the metal under cyclic loading was carried out using the microhardness tester of PMT-3 type.Findings. On the basis of fatigue curves for high-carbon steels analysis the positions of borders dividing the areas of convertible and irreversible damages were determined. The article shows that with the growth of carbon concentration in the steel at invariability of the structural state an increase of fatigue limit is observed. At the same time the acceleration of processes, which determine transition terms from the stage of forming of submicrocracks to the microcracks occurs. The research of microhardness distribution in the metal after destruction confirmed the nature of carbon amount influence on the carbon steel characteristics. Originality. Regardless on the stages of breakdown site forming the carbon steels behavior at a fatigue is determined by the ration between the processes of strengthening and softening. At a cyclic loading the heterogeneity of internal stresses distribution decreases with the increase of distance from the destruction surface. Analysis of metal internal restructuring processes at fatigue loading made it possible to determine that at the stages prior to incubation period in the metal microvolumes the cells are already

  17. Is thermodynamic irreversibility a consequence of the expansion of the Universe?

    Science.gov (United States)

    Osváth, Szabolcs

    2018-02-01

    This paper explains thermodynamic irreversibility by applying the expansion of the Universe to thermodynamic systems. The effect of metric expansion is immeasurably small on shorter scales than intergalactic distances. Multi-particle systems, however, are chaotic, and amplify any small disturbance exponentially. Metric expansion gives rise to time-asymmetric behaviour in thermodynamic systems in a short time (few nanoseconds in air, few ten picoseconds in water). In contrast to existing publications, this paper explains without any additional assumptions the rise of thermodynamic irreversibility from the underlying reversible mechanics of particles. Calculations for the special case which assumes FLRW metric, slow motions (v ≪ c) and approximates space locally by Euclidean space show that metric expansion causes entropy increase in isolated systems. The rise of time-asymmetry, however, is not affected by these assumptions. Any influence of the expansion of the Universe on the local metric causes a coupling between local mechanics and evolution of the Universe.

  18. Time irreversibility and intrinsics revealing of series with complex network approach

    Science.gov (United States)

    Xiong, Hui; Shang, Pengjian; Xia, Jianan; Wang, Jing

    2018-06-01

    In this work, we analyze time series on the basis of the visibility graph algorithm that maps the original series into a graph. By taking into account the all-round information carried by the signals, the time irreversibility and fractal behavior of series are evaluated from a complex network perspective, and considered signals are further classified from different aspects. The reliability of the proposed analysis is supported by numerical simulations on synthesized uncorrelated random noise, short-term correlated chaotic systems and long-term correlated fractal processes, and by the empirical analysis on daily closing prices of eleven worldwide stock indices. Obtained results suggest that finite size has a significant effect on the evaluation, and that there might be no direct relation between the time irreversibility and long-range correlation of series. Similarity and dissimilarity between stock indices are also indicated from respective regional and global perspectives, showing the existence of multiple features of underlying systems.

  19. Linear Dimensional Stability of Irreversible Hydrocolloid Materials Over Time.

    Science.gov (United States)

    Garrofé, Analía B; Ferrari, Beatriz A; Picca, Mariana; Kaplan, Andrea E

    2015-12-01

    The aim of this study was to evaluate the linear dimensional stability of different irreversible hydrocolloid materials over time. A metal mold was designed with custom trays made of thermoplastic sheets (Sabilex, sheets 0.125 mm thick). Perforations were made in order to improve retention of the material. Five impressions were taken with each of the following: Kromopan 100 (LASCOD) [AlKr], which has dimensional stability of 100 hours, and Phase Plus (ZHERMACK) [AlPh], which has dimensional stability of 48 hours. Standardized digital photographs were taken at different time intervals (0, 15, 30, 45, 60, 120 minutes; 12, 24 and 96 hours), using an "ad-hoc" device. The images were analyzed with software (UTHSCSA Image Tool) by measuring the distance between intersection of the lines previously made at the top of the mold. The results were analyzed by ANOVA for repeated measures. Initial and final values were (mean and standard deviation): AlKr: 16.44 (0.22) and 16.34 (0.11), AlPh: 16.40 (0.06) and 16.18 (0.06). Statistical evaluation showed significant effect of material and time factors. Under the conditions in this study, time significantly affects the linear dimensional stability of irreversible hydrocolloid materials. Sociedad Argentina de Investigación Odontológica.

  20. Investigation of Airflow Patterns in a New Design of Wind Tower with a Wetted Surface

    Directory of Open Access Journals (Sweden)

    Madjid Soltani

    2018-04-01

    Full Text Available Passive cooling systems, such as wind towers, can help to reduce energy consumption in buildings and at the same time reduce greenhouse gas (GHG emissions. Wind towers can naturally ventilate buildings and also can create enhanced thermal comfort for occupants during the warm months. This study proposes a modern wind tower design with a moistened pad. The new design includes a fixed column, a rotating and movable head, an air opening with a screen, and two windows at the end of the column. The wind tower can be installed on roof-tops to take advantage of ambient airflow. The wind tower’s head can be controlled manually or automatically to capture optimum wind velocity based on desired thermal condition. To maximize its performance, a small pump was considered to circulate and spray water on an evaporative cooling pad. A computational fluid dynamics (CFD simulation of airflow around and inside the proposed wind tower is conducted to analyze the ventilation performance of this new design of wind tower. Thereby, the velocity, total pressure, and pressure coefficient distributions around and within the wind tower for different wind velocities are examined. The simulation results illustrate that the new wind tower design with a moistened pad can be a reasonable solution to improve naturally the thermal comfort of buildings in hot and dry climates.

  1. Irreversible membrane fouling abatement through pre-deposited layer of hierarchical porous carbons

    KAUST Repository

    Hamad, Juma; Dua, Rubal; Kurniasari, Novita; Kennedy, Maria Dolores; Wang, Peng; Amy, Gary L.

    2014-01-01

    In this work, dual-templated hierarchical porous carbons (HPCs), produced from a coupled ice-hard templating approach, are shown to be a highly effective solution to the commonly occurring problem of irreversible fouling of low-pressure membranes

  2. The association between chronic airflow obstruction and poverty in 12 sites of the multinational BOLD study.

    Science.gov (United States)

    Townend, John; Minelli, Cosetta; Mortimer, Kevin; Obaseki, Daniel O; Al Ghobain, Mohammed; Cherkaski, Hamid; Denguezli, Myriam; Gunesekera, Kirthi; Hafizi, Hasan; Koul, Parvaiz A; Loh, Li C; Nejjari, Chakib; Patel, Jaymini; Sooronbayev, Talant; Buist, Sonia A; Burney, Peter G J

    2017-06-01

    Poverty is strongly associated with mortality from COPD, but little is known of its relation to airflow obstruction.In a cross-sectional study of adults aged ≥40 years from 12 sites (N=9255), participating in the Burden of Obstructive Lung Disease (BOLD) study, poverty was evaluated using a wealth score (0-10) based on household assets. Obstruction, measured as forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) (%) after administration of 200 μg salbutamol, and prevalence of FEV 1 /FVCwealth scores ranged from 4 in Blantyre (Malawi) and Kashmir (India) to 10 in Riyadh (Saudi Arabia), and the prevalence of obstruction, from 16% in Kashmir to 3% in Riyadh and Penang (Malaysia). Following adjustments for age and sex, FEV 1 /FVC increased by 0.36% (absolute change) (95%CI: 0.22, 0.49; pwealth score. Adjustments for other confounders reduced this effect to 0.23% (0.11, 0.34), but even this value remained highly significant (pwealth scores explained 38% of the variation in mean FEV 1 /FVC between sites (r 2 =0.385, p=0.031).Airflow obstruction is consistently associated with poverty at individual and community levels across several countries. Copyright ©ERS 2017.

  3. Numerical analysis of airflow cyclic variation during intake and compression process in a 4-stroke engine

    International Nuclear Information System (INIS)

    Fadzi, M.A.; Zakaria, S.; Yusoff, M.Z; Yusaf, T.

    2004-01-01

    A degree of turbulence is one of the main factors that used to optimize the combustion efficiency, the specific fuel consumption and emissions in automotive engines. A 3D numerical study was prepared to evaluate how the complex geometry of a dome-roof and a pent-roof engine influences the flow field. A 4-stroke, 100cc SI motorcycle engine was used as the model. Engines operating at 1000 rpm and fixed atmospheric conditions were simulated using a commercial computational fluid dynamics (CFD) solver Star CD for cold flow simulations for both induction and compression stroke. Post processing stage was used to observe the cyclic airflows. The simulated results were utilized to compare aerodynamic characteristic in term of swirl and tumble motion. Variations of airflow in the cylinder were viewed through different specific geometry of both combustion chambers. Numerical results show that higher swirl was generated in the dome-roof shape. Results from Star CD simulations were translated into numerical data to compare the value of swirl ratio for both pent-roof and dome-roof engine. Remarkable insights are gained into how the chamber geometry can influence homogeneity of gas mixtures and indirectly affect the efficiency of an engine. (author)

  4. Interferon-gamma improves impaired dentinogenic and immunosuppressive functions of irreversible pulpitis-derived human dental pulp stem cells

    Science.gov (United States)

    Sonoda, Soichiro; Yamaza, Haruyoshi; Ma, Lan; Tanaka, Yosuke; Tomoda, Erika; Aijima, Reona; Nonaka, Kazuaki; Kukita, Toshio; Shi, Songtao; Nishimura, Fusanori; Yamaza, Takayoshi

    2016-01-01

    Clinically, irreversible pulpitis is treated by the complete removal of pulp tissue followed by replacement with artificial materials. There is considered to be a high potential for autologous transplantation of human dental pulp stem cells (DPSCs) in endodontic treatment. The usefulness of DPSCs isolated from healthy teeth is limited. However, DPSCs isolated from diseased teeth with irreversible pulpitis (IP-DPSCs) are considered to be suitable for dentin/pulp regeneration. In this study, we examined the stem cell potency of IP-DPSCs. In comparison with healthy DPSCs, IP-DPSCs expressed lower colony-forming capacity, population-doubling rate, cell proliferation, multipotency, in vivo dentin regeneration, and immunosuppressive activity, suggesting that intact IP-DPSCs may be inadequate for dentin/pulp regeneration. Therefore, we attempted to improve the impaired in vivo dentin regeneration and in vitro immunosuppressive functions of IP-DPSCs to enable dentin/pulp regeneration. Interferon gamma (IFN-γ) treatment enhanced in vivo dentin regeneration and in vitro T cell suppression of IP-DPSCs, whereas treatment with tumor necrosis factor alpha did not. Therefore, these findings suggest that IFN-γ may be a feasible modulator to improve the functions of impaired IP-DPSCs, suggesting that autologous transplantation of IFN-γ-accelerated IP-DPSCs might be a promising new therapeutic strategy for dentin/pulp tissue engineering in future endodontic treatment. PMID:26775677

  5. Interferon-gamma improves impaired dentinogenic and immunosuppressive functions of irreversible pulpitis-derived human dental pulp stem cells.

    Science.gov (United States)

    Sonoda, Soichiro; Yamaza, Haruyoshi; Ma, Lan; Tanaka, Yosuke; Tomoda, Erika; Aijima, Reona; Nonaka, Kazuaki; Kukita, Toshio; Shi, Songtao; Nishimura, Fusanori; Yamaza, Takayoshi

    2016-01-18

    Clinically, irreversible pulpitis is treated by the complete removal of pulp tissue followed by replacement with artificial materials. There is considered to be a high potential for autologous transplantation of human dental pulp stem cells (DPSCs) in endodontic treatment. The usefulness of DPSCs isolated from healthy teeth is limited. However, DPSCs isolated from diseased teeth with irreversible pulpitis (IP-DPSCs) are considered to be suitable for dentin/pulp regeneration. In this study, we examined the stem cell potency of IP-DPSCs. In comparison with healthy DPSCs, IP-DPSCs expressed lower colony-forming capacity, population-doubling rate, cell proliferation, multipotency, in vivo dentin regeneration, and immunosuppressive activity, suggesting that intact IP-DPSCs may be inadequate for dentin/pulp regeneration. Therefore, we attempted to improve the impaired in vivo dentin regeneration and in vitro immunosuppressive functions of IP-DPSCs to enable dentin/pulp regeneration. Interferon gamma (IFN-γ) treatment enhanced in vivo dentin regeneration and in vitro T cell suppression of IP-DPSCs, whereas treatment with tumor necrosis factor alpha did not. Therefore, these findings suggest that IFN-γ may be a feasible modulator to improve the functions of impaired IP-DPSCs, suggesting that autologous transplantation of IFN-γ-accelerated IP-DPSCs might be a promising new therapeutic strategy for dentin/pulp tissue engineering in future endodontic treatment.

  6. Anomalies, Unitarity and Quantum Irreversibility

    CERN Document Server

    Anselmi, D

    1999-01-01

    The trace anomaly in external gravity is the sum of three terms at criticality: the square of the Weyl tensor, the Euler density and Box R, with coefficients, properly normalized, called c, a and a', the latter being ambiguously defined by an additive constant. Unitarity and positivity properties of the induced actions allow us to show that the total RG flows of a and a' are equal and therefore the a'-ambiguity can be consistently removed through the identification a'=a. The picture that emerges clarifies several long-standing issues. The interplay between unitarity and renormalization implies that the flux of the renormalization group is irreversible. A monotonically decreasing a-function interpolating between the appropriate values is naturally provided by a'. The total a-flow is expressed non-perturbatively as the invariant (i.e. scheme-independent) area of the graph of the beta function between the fixed points. We test this prediction to the fourth loop order in perturbation theory, in QCD with Nf ~< ...

  7. Irreversible pulpitis and achieving profound anesthesia: Complexities and managements

    OpenAIRE

    Modaresi, Jalil; Davoudi, Amin; Badrian, Hamid; Sabzian, Roya

    2016-01-01

    Dental pain management is one of the most critical aspects of modern dentistry. Irreversible pulpitis and further root canal therapy might cause an untolerated pain to the patients. The improvements in anesthetic agents and techniques were one of the advantages of studying nerve biology and stimulation. This article tried to overview of the nerve activities in inflammatory environments or induced pain. Furthermore, the proper advises, and supplementary techniques were reviewed for better pain...

  8. Irreversibility and multiplicity: two criteria for the disposal of nuclear wastes

    International Nuclear Information System (INIS)

    Rochlin, G.

    1976-01-01

    Two criteria are suggested for comparing waste management methods: technical irreversibility and site multiplicity. These criteria can be used to reduce future risk in the face of inherent uncertainty and to provide for safe disposal without requiring guaranteed future ability to recognize, detect or repair areas of failure

  9. Numerical simulations of island effects on airflow and weather during the summer over the island of Oahu

    Science.gov (United States)

    Hiep Van Nguyen; Yie-Leng Chen; Francis Fujioka

    2010-01-01

    The high-resolution (1.5 km) nonhydrostatic fifth-generation Pennsylvania StateUniversity–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and an advanced land surface model (LSM) are used to study the island-induced airflow and weather for the island of Oahu, Hawaii, under summer trade wind conditions. Despite Oahu’s relatively small...

  10. Exactly solvable irreversible processes on one-dimensional lattices

    International Nuclear Information System (INIS)

    Wolf, N.O.; Evans, J.W.; Hoffman, D.K.

    1984-01-01

    We consider the kinetics of a process where the sites of an infinite 1-D lattice are filled irreversibly and, in general, cooperatively by N-mers (taking N consecutive sites at a time). We extend the previously available exact solution for nearest neighbor cooperative effects to range N cooperative effects. Connection with the continuous ''cooperative car parking problem'' is indicated. Both uniform and periodic lattices, and empty and certain partially filled lattice initial conditions are considered. We also treat monomer ''filling in stages'' for certain highly autoinhibitory cooperative effects of arbitrary range

  11. Origin of the irreversibility line in thin YBa2Cu3O7-δ films with and without columnar defects

    International Nuclear Information System (INIS)

    Prozorov, R.; Konczykowski, M.; Schmidt, B.; Yeshurun, Y.; Shaulov, A.; Villard, C.; Koren, G.

    1996-01-01

    We report on measurements of the angular dependence of the irreversibility temperature T irr (θ) in YBa 2 Cu 3 O 7-δ thin films, defined by the onset of a third-harmonic signal and measured by a miniature Hall probe. From the functional form of T irr (θ) we conclude that the origin of the irreversibility line in unirradiated films is a dynamic crossover from an unpinned to a pinned vortex liquid. In irradiated films the irreversibility temperature is determined by the trapping angle. copyright 1996 The American Physical Society

  12. Subglottal pressure, tracheal airflow, and intrinsic laryngeal muscle activity during rat ultrasound vocalization

    Science.gov (United States)

    2011-01-01

    Vocal production requires complex planning and coordination of respiratory, laryngeal, and vocal tract movements, which are incompletely understood in most mammals. Rats produce a variety of whistles in the ultrasonic range that are of communicative relevance and of importance as a model system, but the sources of acoustic variability were mostly unknown. The goal was to identify sources of fundamental frequency variability. Subglottal pressure, tracheal airflow, and electromyographic (EMG) data from two intrinsic laryngeal muscles were measured during 22-kHz and 50-kHz call production in awake, spontaneously behaving adult male rats. During ultrasound vocalization, subglottal pressure ranged between 0.8 and 1.9 kPa. Pressure differences between call types were not significant. The relation between fundamental frequency and subglottal pressure within call types was inconsistent. Experimental manipulations of subglottal pressure had only small effects on fundamental frequency. Tracheal airflow patterns were also inconsistently associated with frequency. Pressure and flow seem to play a small role in regulation of fundamental frequency. Muscle activity, however, is precisely regulated and very sensitive to alterations, presumably because of effects on resonance properties in the vocal tract. EMG activity of cricothyroid and thyroarytenoid muscle was tonic in calls with slow or no fundamental frequency modulations, like 22-kHz and flat 50-kHz calls. Both muscles showed brief high-amplitude, alternating bursts at rates up to 150 Hz during production of frequency-modulated 50-kHz calls. A differentiated and fine regulation of intrinsic laryngeal muscles is critical for normal ultrasound vocalization. Many features of the laryngeal muscle activation pattern during ultrasound vocalization in rats are shared with other mammals. PMID:21832032

  13. Combination Therapy for Airflow Limitation In COPD

    Directory of Open Access Journals (Sweden)

    Jafar Aslani

    2012-08-01

    Full Text Available Background and the purpose of the study Existing evidence confirms that no pharmacologic agent ameliorates the decline in the lung function or changes the prognosis of chronic obstructive pulmonary disease (COPD. We tried a critical combination therapy for management of COPD. Methods Current or past smoker (passive or active COPD patients with moderate to severe COPD who did not respond to primitive therapy (i.e., oral prednisolone (50 mg in the morning for 5 days; with Beclomethasone Fort (3 puff q12h, totally 1500 micrograms/day, Salmeterol (2 puffs q12h, 50 micrograms/puff and ipratropium bromide (4 puffs q8h for two months, enrolled to study. Furthermore they were received N-Acetylcysteine (1200 mg/daily, Azithromycin (tablet 250 mg/every other day and Theophylline (100 mg BD.Results The study group consisted of 44 men and 4 women, with a mean age and standard deviation of 63.6+/-12.7 years (range 22-86 years. Thirteen of 48 patients (27.0% was responder based on 15% increasing in FEV 1 (27.7+/-7.9 after 6.7+/-6.1 months (57.9+/-12.9 year old. There were statistically significant differences in age and smoking between responders and nonresponders (P value was 0.05 and 0.04 respectively. There was no difference in emphysema and air trapping between two groups (p=0.13. Conclusion Interestingly considerable proportion of patients with COPD can be reversible using combination drug therapy and patients will greatly benefit from different and synergic action of the drugs. The treatment was more effective in younger patients who smoke less.

  14. Multifractal properties of diffusion-limited aggregates and random multiplicative processes

    International Nuclear Information System (INIS)

    Canessa, E.

    1991-04-01

    We consider the multifractal properties of irreversible diffusion-limited aggregation (DLA) from the point of view of the self-similarity of fluctuations in random multiplicative processes. In particular we analyse the breakdown of multifractal behaviour and phase transition associated with the negative moments of the growth probabilities in DLA. (author). 20 refs, 5 figs

  15. Coupled Reversible and Irreversible Bistable Switches Underlying TGFβ-induced Epithelial to Mesenchymal Transition

    Science.gov (United States)

    Tian, Xiao-Jun; Zhang, Hang; Xing, Jianhua

    2013-01-01

    Epithelial to mesenchymal transition (EMT) plays an important role in embryonic development, tissue regeneration, and cancer metastasis. Whereas several feedback loops have been shown to regulate EMT, it remains elusive how they coordinately modulate EMT response to TGF-β treatment. We construct a mathematical model for the core regulatory network controlling TGF-β-induced EMT. Through deterministic analyses and stochastic simulations, we show that EMT is a sequential two-step program in which an epithelial cell first is converted to partial EMT then to the mesenchymal state, depending on the strength and duration of TGF-β stimulation. Mechanistically the system is governed by coupled reversible and irreversible bistable switches. The SNAIL1/miR-34 double-negative feedback loop is responsible for the reversible switch and regulates the initiation of EMT, whereas the ZEB/miR-200 feedback loop is accountable for the irreversible switch and controls the establishment of the mesenchymal state. Furthermore, an autocrine TGF-β/miR-200 feedback loop makes the second switch irreversible, modulating the maintenance of EMT. Such coupled bistable switches are robust to parameter variation and molecular noise. We provide a mechanistic explanation on multiple experimental observations. The model makes several explicit predictions on hysteretic dynamic behaviors, system response to pulsed stimulation, and various perturbations, which can be straightforwardly tested. PMID:23972859

  16. Abnormalities in lung volumes and airflow in children with newly diagnosed connective tissue disease.

    Science.gov (United States)

    Peradzyńska, Joanna; Krenke, Katarzyna; Szylling, Anna; Kołodziejczyk, Beata; Gazda, Agnieszka; Rutkowska-Sak, Lidia; Kulus, Marek

    2016-01-01

    Connective tissue diseases (CTDs) of childhood are rare inflammatory disorders, involving various organs and tissues including respiratory system. Pulmonary involvement in patients with CTDs is uncommon but may cause functional impairment. Data on prevalence and type of lung function abnormalities in children with CTDs are scarce. Thus, the aim of this study was to asses pulmonary functional status in children with newly diagnosed CTD and follow the results after two years of the disease course. There were 98 children (mean age: 13 ± 3; 76 girls), treated in Department of Pediatric Rheumatology, Institute of Rheumatology, Warsaw and 80 aged-matched, healthy controls (mean age 12.7 ± 2.4; 50 girls) included into the study. Study procedures included medical history, physical examination, chest radiograph and PFT (spirometry and whole body-plethysmography). Then, the assessment of PFT was performed after 24 months. FEV₁, FEV₁/FVC and MEF50 were significantly lower in CTD as compared to control group, there was no difference in FVC and TLC. The proportion of patients with abnormal lung function was significantly higher in the study group, 41 (42%) vs 9 (11%). 24-months observation didn't reveal progression in lung function impairment. Lung function impairment is relatively common in children with CTDs. Although restrictive ventilatory pattern is considered typical feature of lung involvement in CTDs, airflow limitation could also be an initial abnormality.

  17. Characterization of bio-inspired hair flow sensors for oscillatory airflows: techniques to measure the response for both flow and pressure

    NARCIS (Netherlands)

    Droogendijk, H.; Dagamseh, A.M.K.; Sanders, Remco G.P.; Yntema, Doekle Reinder; Krijnen, Gijsbertus J.M.

    2014-01-01

    Hair sensors for oscillatory airflow, operating in the regime of bulk flow, particle velocity or both, can be characterized by several methods. In this work, we discuss harmonic measurements on MEMS hair flow sensors. To characterize this type of flow sensor the use of three different types of

  18. Model of the Evolution of Deformation Defects and Irreversible Strain at Thermal Cycling of Stressed TiNi Alloy Specimen

    Directory of Open Access Journals (Sweden)

    Volkov Aleksandr E.

    2015-01-01

    Full Text Available This microstructural model deals with simulation both of the reversible and irreversible deformation of a shape memory alloy (SMA. The martensitic transformation and the irreversible deformation due to the plastic accommodation of martensite are considered on the microscopic level. The irreversible deformation is described from the standpoint of the plastic flow theory. Isotropic hardening and kinematic hardening are taken into account and are related to the densities of scattered and oriented deformation defects. It is supposed that the phase transformation and the micro plastic deformation are caused by the generalized thermodynamic forces, which are the derivatives of the Gibbs’ potential of the two-phase body. In terms of these forces conditions for the phase transformation and for the micro plastic deformation on the micro level are formulated. The macro deformation of the representative volume of the polycrystal is calculated by averaging of the micro strains related to the evolution of the martensite Bain’s variants in each grain comprising this volume. The proposed model allowed simulating the evolution of the reversible and of the irreversible strains of a stressed SMA specimen under thermal cycles. The results show a good qualitative agreement with available experimental data. Specifically, it is shown that the model can describe a rather big irreversible strain in the first thermocycle and its fast decrease with the number of cycles.

  19. New insight into the evolution of the vertebrate respiratory system and the discovery of unidirectional airflow in iguana lungs.

    Science.gov (United States)

    Cieri, Robert L; Craven, Brent A; Schachner, Emma R; Farmer, C G

    2014-12-02

    The generally accepted framework for the evolution of a key feature of the avian respiratory system, unidirectional airflow, is that it is an adaptation for efficiency of gas exchange and expanded aerobic capacities, and therefore it has historically been viewed as important to the ability of birds to fly and to maintain an endothermic metabolism. This pattern of flow has been presumed to arise from specific features of the respiratory system, such as an enclosed intrapulmonary bronchus and parabronchi. Here we show unidirectional airflow in the green iguana, a lizard with a strikingly different natural history from that of birds and lacking these anatomical features. This discovery indicates a paradigm shift is needed. The selective drivers of the trait, its date of origin, and the fundamental aerodynamic mechanisms by which unidirectional flow arises must be reassessed to be congruent with the natural history of this lineage. Unidirectional flow may serve functions other than expanded aerobic capacity; it may have been present in the ancestral diapsid; and it can occur in structurally simple lungs.

  20. A model of irreversible jam formation in dense traffic

    Science.gov (United States)

    Brankov, J. G.; Bunzarova, N. Zh.; Pesheva, N. C.; Priezzhev, V. B.

    2018-03-01

    We study an one-dimensional stochastic model of vehicular traffic on open segments of a single-lane road of finite size L. The vehicles obey a stochastic discrete-time dynamics which is a limiting case of the generalized Totally Asymmetric Simple Exclusion Process. This dynamics has been previously used by Bunzarova and Pesheva (2017) for an one-dimensional model of irreversible aggregation. The model was shown to have three stationary phases: a many-particle one, MP, a phase with completely filled configuration, CF, and a boundary perturbed MP+CF phase, depending on the values of the particle injection (α), ejection (β) and hopping (p) probabilities. Here we extend the results for the stationary properties of the MP+CF phase, by deriving exact expressions for the local density at the first site of the chain and the probability P(1) of a completely jammed configuration. The unusual phase transition, characterized by jumps in both the bulk density and the current (in the thermodynamic limit), as α crosses the boundary α = p from the MP to the CF phase, is explained by the finite-size behavior of P(1). By using a random walk theory, we find that, when α approaches from below the boundary α = p, three different regimes appear, as the size L → ∞: (i) the lifetime of the gap between the rightmost clusters is of the order O(L) in the MP phase; (ii) small jams, separated by gaps with lifetime O(1) , exist in the MP+CF phase close to the left chain boundary; and (iii) when β = p, the jams are divided by gaps with lifetime of the order O(L 1 / 2) . These results are supported by extensive Monte Carlo calculations.

  1. Irreversibility in physics stemming from unpredictable symbol-handling agents

    Science.gov (United States)

    Myers, John M.; Madjid, F. Hadi

    2016-05-01

    The basic equations of physics involve a time variable t and are invariant under the transformation t --> -t. This invariance at first sight appears to impose time reversibility as a principle of physics, in conflict with thermodynamics. But equations written on the blackboard are not the whole story in physics. In prior work we sharpened a distinction obscured in today's theoretical physics, the distinction between obtaining evidence from experiments on the laboratory bench and explaining that evidence in mathematical symbols on the blackboard. The sharp distinction rests on a proof within the mathematics of quantum theory that no amount of evidence, represented in quantum theory in terms of probabilities, can uniquely determine its explanation in terms of wave functions and linear operators. Building on the proof we show here a role in physics for unpredictable symbol-handling agents acting both at the blackboard and at the workbench, communicating back and forth by means of transmitted symbols. Because of their unpredictability, symbol-handling agents introduce a heretofore overlooked source of irreversibility into physics, even when the equations they write on the blackboard are invariant under t --> -t. Widening the scope of descriptions admissible to physics to include the agents and the symbols that link theory to experiments opens up a new source of time-irreversibility in physics.

  2. Concerning the study of the irreversible magnetic behaviour of superconductivity; Contribution a l'etude du comportement magnetique irreversible des supraconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, G [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-03-01

    The influence of the presence of extended lattice defects on the magnetic behaviour has been studied for the case of type I superconductors, such as Re and Ta, and in a more quantitative manner for the type II superconductor niobium. In this case, measurements of the thermal conductivity have given an estimate of the relative concentration of lattice defects in each specimen. These measurements show that the larger the number of lattice defects, the more irreversible becomes the magnetization curve, and the larger becomes the values of the critical current, which is related by a simple model to the magnetization values. Finally, a study by transmission electron microscopy has confirmed on the one hand the diversity of the extended lattice defects and on the other hand has allowed the formulation of several hypothesis on their respective influence. [French] L'influence de la presence de defauts etendus sur le comportement magnetique a ete etudie pour des supraconducteurs de premiere espece, tels que le rhenium et le tantale, et plus quantitativement pour un supraconducteur de deuxieme espece, le niobium. Dans ce cas, des mesures de conductibilite thermique ont permis d'estimer la concentration relative des defauts du reseau dans chaque echantillon. Ces mesures montrent que plus les defauts du reseau sont nombreux, plus la courbe d'aimantation est irreversible, et plus les valeurs du courant critique, reliees par un modele simple aux valeurs de l'aimantation, sont elevees. Enfin une etude par microscopie electronique en transmission - a permis d'une part de constater la diversite des defauts etendus et d'autre part de formuler quelques hypotheses sur leurs influences respectives.

  3. Application of exergetic sustainability index to a nano-scale irreversible Brayton cycle operating with ideal Bose and Fermi gasses

    Energy Technology Data Exchange (ETDEWEB)

    Açıkkalp, Emin, E-mail: eacikkalp@gmail.com [Department of Mechanical and Manufacturing Engineering, Engineering Faculty, Bilecik S.E. University, Bilecik (Turkey); Caner, Necmettin [Department of Chemistry, Faculty of Arts and Sciences, Eskisehir Osmangazi University, Eskisehir (Turkey)

    2015-09-25

    Highlights: • An irreversible Brayton cycle operating quantum gasses is considered. • Exergetic sustainability index is derived for nano-scale cycles. • Nano-scale effects are considered. • Calculation are conducted for irreversible cycles. • Numerical results are presented and discussed. - Abstract: In this study, a nano-scale irreversible Brayton cycle operating with quantum gasses including Bose and Fermi gasses is researched. Developments in the nano-technology cause searching the nano-scale machines including thermal systems to be unavoidable. Thermodynamic analysis of a nano-scale irreversible Brayton cycle operating with Bose and Fermi gasses was performed (especially using exergetic sustainability index). In addition, thermodynamic analysis involving classical evaluation parameters such as work output, exergy output, entropy generation, energy and exergy efficiencies were conducted. Results are submitted numerically and finally some useful recommendations were conducted. Some important results are: entropy generation and exergetic sustainability index are affected mostly for Bose gas and power output and exergy output are affected mostly for the Fermi gas by x. At the high temperature conditions, work output and entropy generation have high values comparing with other degeneracy conditions.

  4. Entransy analysis of irreversible heat pump using Newton and Dulong–Petit heat transfer laws and relations with its performance

    International Nuclear Information System (INIS)

    Açıkkalp, Emin

    2014-01-01

    Highlights: • Entransy analysis was made for irreversible heat pump. • Newton and Dulong–Petit heat transfer laws were used. • Entransy dissipations were defined and determined. • Relations between entransy and other thermodynamic parameters were determined. - Abstract: An irreversible heat pump was investigated via entransy analysis and performance criteria. In the analyses, two different convective heat transfer laws were applied to the considered system: the Newton and Dulong–Petit heat transfer laws. The irreversibilities in the system are the result of a finite heat transfer rate, a heat leak and internal irreversibilities, including friction, turbulence etc. In this study, a thermodynamic analysis was performed in detail, and the numerical solutions were used for the conducted analysis. The maximum entransy dissipation (critical points) ranges from 18436.7 kW K to 18855.3 kW K according to y for Newton’s law; however, there is no maximum point for the Dulon–Petit law. It can be concluded from this study that entransy should be used among the basic thermodynamic criteria

  5. Visualization of nasal airflow patterns in a patient affected with atrophic rhinitis using particle image velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, G J M [Hamner Institutes for Health Sciences, NC (United States); Mitchell, G [The Queens University of Belfast, Belfast (United Kingdom); Bailie, N [The Queens University of Belfast, Belfast (United Kingdom); Thornhill, D [The Queens University of Belfast, Belfast (United Kingdom); Watterson, J [The Queens University of Belfast, Belfast (United Kingdom); Kimbell, J S [Hamner Institutes for Health Sciences, NC (United States)

    2007-10-15

    The relationship between airflow patterns in the nasal cavity and nasal function is poorly understood. This paper reports an experimental study of the interplay between symptoms and airflow patterns in a patient affected with atrophic rhinitis. This pathology is characterized by mucosal dryness, fetor, progressive atrophy of anatomical structures, a spacious nasal cavity, and a paradoxical sensation of nasal congestion. A physical replica of the patient's nasal geometry was made and particle image velocimetry (PIV) was used to visualize and measure the flow field. The nasal replica was based on computed tomography (CT) scans of the patient and was built in three steps: three-dimensional reconstruction of the CT scans; rapid prototyping of a cast; and sacrificial use of the cast to form a model of the nasal passage in clear silicone. Flow patterns were measured by running a water-glycerol mixture through the replica and evaluating the displacement of particles dispersed in the liquid using PIV. The water-glycerol flow rate used corresponded to an air flow rate representative of a human breathing at rest. The trajectory of the flow observed in the left passage of the nose (more affected by atrophic rhinitis) differed markedly from what is considered normal, and was consistent with patterns of epithelial damage observed in cases of the condition. The data are also useful for validation of computational fluid dynamics predictions.

  6. Optimal allocation of thermodynamic irreversibility for the integrated design of propulsion and thermal management systems

    Science.gov (United States)

    Maser, Adam Charles

    work losses over the time history of the mission. The characterization of the thermodynamic irreversibility distribution helps give the propulsion systems designer an absolute and consistent view of the tradeoffs associated with the design of the entire integrated system. Consequently, this leads directly to the question of the proper allocation of irreversibility across each of the components. The process of searching for the most favorable allocation of this irreversibility is the central theme of the research and must take into account production cost and vehicle mission performance. The production cost element is accomplished by including an engine component weight and cost prediction capability within the system model. The vehicle mission performance is obtained by directly linking the propulsion and thermal management model to a vehicle performance model and flying it through a mission profile. A canonical propulsion and thermal management systems architecture is then presented to experimentally test each element of the methodology separately: first the integrated modeling and simulation, then the irreversibility, cost, and mission performance considerations, and then finally the proper technique to perform the optimal allocation. A goal of this research is the description of the optimal allocation of system irreversibility to enable an engine cycle design with improved performance and cost at the vehicle-level. To do this, a numerical optimization was first used to minimize system-level production and operating costs by fixing the performance requirements and identifying the best settings for all of the design variables. There are two major drawbacks to this approach: It does not allow the designer to directly trade off the performance requirements and it does not allow the individual component losses to directly factor into the optimization. An irreversibility allocation approach based on the economic concept of resource allocation is then compared to the

  7. [Dynamics of Irreversible Evaporation of a Water-Protein Droplet and a Problem of Structural and Dynamical Experiments with Single Molecules].

    Science.gov (United States)

    Shaitan, K V; Armeev, G A; Shaytan, A K

    2016-01-01

    We discuss the effect of isothermal and adiabatic evaporation of water on the state of a water-protein droplet. The discussed problem is of current importance due to development of techniques to perform single molecule experiments using free electron lasers. In such structure-dynamic experiments the delivery of a sample into the X-ray beam is performed using the microdroplet injector. The time between the injection and delivery is in the order of microseconds. In this paper we developed a specialized variant of all-atom molecular dynamics simulations for the study of irreversible isothermal evaporation of the droplet. Using in silico experiments we determined the parameters of isothermal evaporation of the water-protein droplet with the sodium and chloride ions in the concentration range of 0.3 M at different temperatures. The energy of irreversible evaporation determined from in silico experiments at the initial stages of evaporation virtually coincides with the specific heat of evaporation for water. For the kinetics of irreversible adiabatic evaporation an exact analytical solution was obtained in the limit of high thermal conductivity of the droplet (or up to the droplet size of -100 Å). This analytical solution incorporates parameters that are determined using in silico. experiments on isothermal droplet evaporation. We show that the kinetics of adiabatic evaporation and cooling of the droplet scales with the droplet size. Our estimates of the water-protemi droplet. freezing rate in the adiabatic regime in a vacuum chamber show that additional techniques for stabilizing the temperature inside the droplet should be used in order to study the conformational transitions of the protein in single molecules. Isothermal and quasi-isothermal conditions are most suitable for studying the conformational transitions upon object functioning. However, in this case it is necessary to take into account the effects of dehydration and rapid increase of ionic strength in an

  8. Thermodynamic restrictions on linear reversible and irreversible thermo-electro-magneto-mechanical processes

    Directory of Open Access Journals (Sweden)

    Sushma Santapuri

    2016-10-01

    Full Text Available A unified thermodynamic framework for the characterization of functional materials is developed. This framework encompasses linear reversible and irreversible processes with thermal, electrical, magnetic, and/or mechanical effects coupled. The comprehensive framework combines the principles of classical equilibrium and non-equilibrium thermodynamics with electrodynamics of continua in the infinitesimal strain regime.In the first part of this paper, linear Thermo-Electro-Magneto-Mechanical (TEMM quasistatic processes are characterized. Thermodynamic stability conditions are further imposed on the linear constitutive model and restrictions on the corresponding material constants are derived. The framework is then extended to irreversible transport phenomena including thermoelectric, thermomagnetic and the state-of-the-art spintronic and spin caloritronic effects. Using Onsager's reciprocity relationships and the dissipation inequality, restrictions on the kinetic coefficients corresponding to charge, heat and spin transport processes are derived. All the constitutive models are accompanied by multiphysics interaction diagrams that highlight the various processes that can be characterized using this framework. Keywords: Applied mathematics, Materials science, Thermodynamics

  9. Thermal mechanisms responsible for the irreversible degradation of superconductivity in commercial superconductors

    Science.gov (United States)

    Romanovskii, V. R.

    2017-08-01

    Conditions for the irreversible propagation of thermal instabilities in commercial superconductors subjected to intense and soft cooling have been formulated. An analysis has been conducted using two types of the superconductor's I-V characteristics, i.e., an ideal I-V characteristic, which assumes a step superconducting-to-normal transition, and a continuous I-V characteristic, which is described by a power law. The propagation rate of thermal instabilities along the superconducting composite has been determined. Calculations have been made for both subcritical and supercritical values of the current. It has been shown that they propagate along a commercial superconductor in the form of a switching wave. In rapidly cooled commercial superconductors, the steady-state rate of thermal instability propagation in the longitudinal direction can only be positive because there is no region of steady stabilization. It has been proved that, in the case of thermal instability irreversible propagation, the rise in the commercial superconductor temperature is similar to diffusion processes that occur in explosive chain reactions.

  10. Numerical analysis of the actual airflow in a solar chimney; Analise numerica do escoamento real de ar em uma chamine solar

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Andre G.; Cortez, Marcio F.B.; Valle, Ramon M.; Brasil, Cristiana S. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Engenharia Mecanica]. E-mail: ferreira@demec.ufmg.br; fonteboa@demec.ufmg.br; ramon@demec.ufmg.br; tite@demec.ufmg.br

    2000-07-01

    This paper presents a numerical analysis of the turbulent natural convection of the airflow in a solar chimney, under actual solar radiation conditions. The solar chimneys are devices that consist of a transparent radial cover and of a tubular tower positioned in its center. The ground absorbs part of the incident solar radiation on the cover, heating the air in the greenhouse and inducing an upward airflow on the tower. It was developed a model that allows the evaluation of the ground temperature as a function of an energetic balance involving the incident solar radiation. The flow is described by the conservation laws for mass, momentum and thermal energy and the transport equations for the turbulence model (k and e ). A computational code using the Finite Volume Method in Generalized Coordinates was developed to solve these equations. Outlet dimensionless parameters are presented as functions of the radiation time and conditions, besides the unsteady behavior of the ground surface temperature. (author)

  11. Beta-lactam antibiotic-induced platelet dysfunction: Evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

    International Nuclear Information System (INIS)

    Burroughs, S.F.; Johnson, G.J.

    1990-01-01

    beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of [14C]-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; but no irreversible inhibition of alpha 2 adrenergic receptors, measured with [3H]-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist [3H]-U46619 and antagonist [3H]-SQ29548, occurred. However, low-affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ([Ca2+]i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in [Ca2+]i. The loss of low-affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane

  12. Effect of preoperative alprazolam on the success of inferior alveolar nerve block for teeth with irreversible pulpitis.

    Science.gov (United States)

    Khademi, Abbas Ali; Saatchi, Masoud; Minaiyan, Mohsen; Rostamizadeh, Nasim; Sharafi, Fatemeh

    2012-10-01

    Success of inferior alveolar nerve (IAN) block decreases in patients with irreversible pulpitis. The purpose of this study was to evaluate the effect of preoperative administration of alprazolam on the success of the IAN block for teeth with irreversible pulpitis. Sixty patients with irreversible pulpitis of a mandibular molar were selected for this prospective, randomized, double-blind, placebo-controlled study. The patients received identical capsules of either 0.5 mg of alprazolam or placebo 45 minutes before the administration of a conventional IAN block. Access cavity preparation was initiated 15 minutes after the IAN block injection. Lip numbness was recorded for all the patients. Success was defined as no or mild pain on the basis of visual analogue scale recordings during access cavity preparation and initial instrumentation. Data were analyzed by t test, Mann-Whitney, and χ(2) tests. The success rate was 53% for alprazolam group and 40% for placebo group, with no significant difference between the 2 groups (P = .301). Within the scope of the current study, preoperative oral administration of 0.5 mg of alprazolam did not improve the success of the IAN block in mandibular molars in patients with irreversible pulpitis, and the success rate was not adequate to ensure profound pulpal anesthesia. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  13. Conducts of disinfection, pouring and storage of irreversible hydrocolloid impressions by undergraduate students

    Directory of Open Access Journals (Sweden)

    Thalisson Saymo de Oliveira SILVA

    Full Text Available Abstract Introduction Obtaining dental models that accurately represent the molded oral tissue requires professional attention, especially when using irreversible hydrocolloid as a molding material. Objective To evaluate the conducts of undergraduate dental students at different internships for the disinfecting procedures, pouring, and storage of irreversible hydrocolloid impressions. Material and method This is an observational, cross-sectional and descriptive study with a census sample of 89 students enrolled in the supervised internships I, II, III and IV. Data collection was performed using a structured questionnaire containing eight questions. Data were analyzed at the 5% significance level. Result Most of the students (88.8% performed the disinfection procedure, for which the most widely used method (64.6% was the application of sodium hypochlorite 1% spray stored in a sealed container. The most common disinfection time was 10 minutes (86.1%. Students in the early internships performed better in regard to the proportion of water/plaster to be used compared with students in the final internships. At all internships, pouring and storage of the ensemble of mold and model were neglected during the setting reaction. There was a statistically significant association between the stage and the disinfection method, the ratio of water/powder and pouring of the model (p<0.05. Conclusion Students exhibited appropriate conduct of disinfection; however, they should be encouraged to use evidence-based clinical practices in order to improve the procedures of pouring and storage of irreversible hydrocolloid molds.

  14. Antibiotics are not useful to reduce pain associated with irreversible pulpitis.

    Science.gov (United States)

    Hoskin, Eileen; Veitz-Keenan, Analia

    2016-09-01

    Data sourcesCochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Clinical Trials.gov and the WHO International Clinical Trials Registry Platform. There were no language restrictions.Study selectionRandomised controlled trials which compared the relief of pain with systemic antibiotics and analgesics against placebo and analgesics in the preoperative phase of irreversible pulpitis. The primary interest was pain control with an antibiotic or without one in the presence of analgesics. The secondary outcomes were type, dose and frequency of medication for pain relief and any adverse effects related to hypersensitivity or other reactions to either the antibiotic or analgesics.Data extraction and synthesisTwo authors independently assessed the results of the searches. Data extraction and risk bias assessment were also carried out independently. A third reviewer settled any disagreement on inclusion. Since only one study was included a meta-analysis could not be performed.ResultsOnly one double blind randomised clinical trial involving 40 participants with a diagnosis of irreversible pulpitis in one of their teeth was included in this review. This was a low risk, well-constructed double blind study. Half of the participants were treated with penicillin 500 mg, the other with a placebo every six hours over a seven- day period. In addition, all the participants were instructed to initially take one tablet of ibuprofen every 4-6 hours as needed and to take acetaminophen with codeine (two tablets every 4-6 hours) only if the ibuprofen did not relieve the pain.There was no significant difference in the mean total number of ibuprofen tablets over the study period; 9.2(standard deviation (SD) 6.02) in the penicillin group versus, 9.6 (SD 6.34) in the placebo group; mean difference -0.40 (95% CI -4.23 to 3.43); P value = 0.84.The mean total number of Tylenol tablets, 6.9 (SD 6.87), used in the penicillin group versus 4

  15. Irreversibility in room temperature current–voltage characteristics of NiFe{sub 2}O{sub 4} nanoparticles: A signature of electrical memory effect

    Energy Technology Data Exchange (ETDEWEB)

    Dey, P., E-mail: pujaiitkgp2007@gmail.com [Department of Physics, Kazi Nazrul University, Asansol, W.B. 713340 (India); Debnath, Rajesh; Singh, Swati; Mandal, S.K. [Department of Physics, National Institute of Technology Agartala, Tripura 799046 (India); Roy, J.N. [Department of Physics, Kazi Nazrul University, Asansol, W.B. 713340 (India); Department of Physics, National Institute of Technology Agartala, Tripura 799046 (India)

    2017-01-01

    Room temperature I–V characteristics study, both in presence and absence of magnetic field (1800 Oe), has been performed on NiFe{sub 2}O{sub 4} nanoparticles, having different particle size (φ~14, 21 and 31 nm). Our experiments on these nanoparticles provide evidences for: (1) electrical irreversibility or hysteretic behaviour; (2) positive magnetoresistance and (3) magnetic field dependent electrical irreversibility or hysteresis in the sample. “Hysteretic” nature of I–V curve reveals the existence of electrical memory effect in the sample. Significantly, such hysteresis has been found to be tuned by magnetic field. In order to explain the observed electrical irreversibility, we have proposed a phenomenological model on the light of induced polarization in the sample. Both the positive magnetoresistance and the observed magnetic field dependence of electrical irreversibility have been explained through magnetostriction phenomenon. Interestingly, such effects are found to get reduced with increasing particle size. For NiFe{sub 2}O{sub 4} nanoparticles having φ=31 nm, we did not observe any irreversibility effect. This feature has been attributed to the enhanced grain surface effect that in turn gives rise to the residual polarization and hence electrical memory effect in NiFe{sub 2}O{sub 4} nanoparticles, having small nanoscopic particle size. - Highlights: • I-V characteristics study of NiFe{sub 2}O{sub 4} nanoparticles with varying particle sizes. • Experiments evident electrical hysteretic behaviour, i.e., electrical memory effect. • Magnetic field dependent electrical irreversibility is due to magnetostriction. • A phenomenological model has been proposed on the light of induced polarization. • Such electrical irreversibility decreases with increasing particle sizes.

  16. Electrochemical characterization of irreversibly adsorbed germanium on platinum stepped surfaces vicinal to Pt(1 0 0)

    International Nuclear Information System (INIS)

    Rodriguez, P.; Herrero, E.; Solla-Gullon, J.; Vidal-Iglesias, F.J.; Aldaz, A.; Feliu, J.M.

    2005-01-01

    The electrochemical behavior of germanium irreversibly adsorbed at stepped surfaces vicinal to the Pt(1 0 0) pole is reported. The process taking part on the (1 0 0) terraces is evaluated from charge density measurements and calibration lines versus the terrace dimension are plotted. On the series Pt(2n - 1,1,1) having (1 1 1) monoatomic steps, the charge involved in the redox process undergone by the irreversibly adsorbed germanium is able to account for (n - 0.5) terrace atoms, thus suggesting some steric difficulties in the growth of the adlayer on the (1 0 0) terraces. Conversely, no steric problems are apparent in the series Pt(n,1,0) in which more open (1 0 0) steps are present on the (1 0 0) terraces. In this latter case the charge density under the germanium redox peaks is proportional to the number of terrace atoms. Some comparison is made with other stepped surfaces to understand the behavior and stability of germanium irreversibly adsorbed on the different platinum surface sites

  17. Effects of single-sided inferior turbinectomy on nasal function and airflow characteristics.

    Science.gov (United States)

    Na, Yang; Chung, Kang Soo; Chung, Seung-Kyu; Kim, Sung Kyun

    2012-03-15

    Knowledge of airflow characteristics in the nasal cavity is essential to understanding the physiologic and pathologic aspects of nasal breathing. Airflows inside post-surgery models were investigated both experimentally and numerically to simulate the inferior turbinectomy. The left cavities of all three models are normal and right cavity is modified by (1) excision of the head of the inferior turbinate, (2) resection of the lower fifth of the inferior turbinate, and (3) resection of almost the entire inferior turbinate. Thin-slice CT (computed tomography) data (0.6mm deep) and meticulous refinement of the model surface by over a decade-long collaboration between engineers and an experienced ENT doctor resulted in the creation of sophisticated nasal cavity models. After numerical experiments and validation by comparison with the PIV results, the CFD code using the Reynolds stress turbulent model and variable temperature boundary condition on the mucosal wall was chosen as the proper numerical framework. Both global quantities (pressure drop, flow rate ratio, total wall heat transfer) and local changes (velocity, temperature, humidity, pressure gradient, and wall shear stress) were numerically investigated. The turbinectomy obviously altered the main stream direction. The flow rate in the upper airway near the olfactory slit decreased in models (1) and (3). This may weaken the olfactory function of the nose. Fluid and thermal properties that are believed to be related with physiology and prognosis are dependent on turbinate resection volume, position, and manner. Widening of the inferior airway does not always result in decreased flow resistance or wall heat transfer. The gains and losses of inferior turbinectomy were considered by analysis of the post-surgery model results. Nasal resistance was increased in model (1) due to sudden airway expansion. Nasal resistance increased and the wall heat transfer decreased in model (3) due to sudden airway expansion and

  18. Surface potential distribution and airflow performance of different air-exposed electrode plasma actuators at different alternating current/direct current voltages

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liang; Yan, Hui-Jie; Qi, Xiao-Hua; Hua, Yue; Ren, Chun-Sheng, E-mail: rchsh@dlut.edu.cn [School of Physics and Optoelectronic Technology, Key laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116023 (China)

    2015-04-15

    Asymmetric surface dielectric barrier discharge (SDBD) plasma actuators have been intensely studied for a number of years due to their potential applications for aerodynamic control. In this paper, four types of actuators with different configurations of exposed electrode are proposed. The SDBD actuators investigated are driven by dual-power supply, referred to as a fixed AC high voltage and an adjustable DC bias. The effects of the electrode structures on the dielectric surface potential distribution, the electric wind velocity, and the mean thrust production are studied, and the dominative factors of airflow acceleration behavior are revealed. The results have shown that the actions of the SDBD actuator are mainly dependent on the geometry of the exposed electrode. Besides, the surface potential distribution can effectively affect the airflow acceleration behavior. With the application of an appropriate additional DC bias, the surface potential will be modified. As a result, the performance of the electric wind produced by a single SDBD can be significantly improved. In addition, the work also illustrates that the actuators with more negative surface potential present better mechanical performance.

  19. Surface potential distribution and airflow performance of different air-exposed electrode plasma actuators at different alternating current/direct current voltages

    International Nuclear Information System (INIS)

    Yang, Liang; Yan, Hui-Jie; Qi, Xiao-Hua; Hua, Yue; Ren, Chun-Sheng

    2015-01-01

    Asymmetric surface dielectric barrier discharge (SDBD) plasma actuators have been intensely studied for a number of years due to their potential applications for aerodynamic control. In this paper, four types of actuators with different configurations of exposed electrode are proposed. The SDBD actuators investigated are driven by dual-power supply, referred to as a fixed AC high voltage and an adjustable DC bias. The effects of the electrode structures on the dielectric surface potential distribution, the electric wind velocity, and the mean thrust production are studied, and the dominative factors of airflow acceleration behavior are revealed. The results have shown that the actions of the SDBD actuator are mainly dependent on the geometry of the exposed electrode. Besides, the surface potential distribution can effectively affect the airflow acceleration behavior. With the application of an appropriate additional DC bias, the surface potential will be modified. As a result, the performance of the electric wind produced by a single SDBD can be significantly improved. In addition, the work also illustrates that the actuators with more negative surface potential present better mechanical performance

  20. IRREVERSIBILITY GENERATION IN SUGAR, ALCOHOL AND BIOGAS INTEGRATED PRODUCTIONS

    Directory of Open Access Journals (Sweden)

    Meilyn González Cortés

    2017-01-01

    Full Text Available In this work, the stages of losses and lower exergetic efficiency are determined when the sugar production process is integrated with others for the production of products such as biogas, torula yeast and electricity. The study is carried out in three scenarios of integrated processes for obtaining the indicated products. A sugar factory in which sugar and electricity are produced is considered as the base scenario and from this; a second scenario is inferred in which alcohol is produced from the molasses of the sugar process and biogas from the vinasse of the alcohol distillation process. Finally, a third scenario is exergetically evaluated in which sugar, electricity, biogas and alcohol are produced, but this last one from juices and molasses of the sugar process. For the exergetic analysis the integrated scheme was divided into 8 subsystems. From the analysis of results, the major subsystems that generate irreversibilities are: cogeneration (64.36-65.98%, juice extraction (8.85-9.85%, crystallization and cooking, (8.48 -9.02%, fermentation (4.12-4.94% and distillation (2.74-3.2%. Improvements are proposed to minimize irreversibilities, including the thermal integration of processes, technological modifications in the fermentation process and the introduction of more efficient equipment for the generation of electricity. The exergetic efficiency is between 78.95-81.10%, obtaining greater exergetic efficiency in the scheme of joint operation to produce sugar, alcohol and biogas.

  1. The influence of airflow inlet region modifications on the local efficiency of natural draft cooling tower operation

    OpenAIRE

    Hočevar, Marko; Širok, Brane; Dvoršek, Matjaž; Holeček, Nikola; Donevski, Božin

    2015-01-01

    We present the influence of the cooling tower airflow inlet region modifications at the Šoštanj 4 thermal power plant on cooling tower local efficiency. Local efficiency change was estimated based on temperature fields of drift eliminators before and after the reconstruction of the cooling tower. Temperature fields were measured with thermal vision method. The local reduction of cooling tower efficiency was analyzed based on phenomenological relations of heat transfer obtained from the select...

  2. Strategies to overcome oxygen transfer limitations during hairy root cultivation of Azadiracta indica for enhanced azadirachtin production.

    Science.gov (United States)

    Srivastava, Smita; Srivastava, Ashok Kumar

    2012-07-01

    The vast untapped potential of hairy root cultures as a stable source of biologically active chemicals has focused the attention of scientific community toward its commercial exploitation. However, the major bottleneck remains its successful scale-up. Due to branching, the roots form an interlocked matrix that exhibits resistance to oxygen transfer. Thus, present work was undertaken to develop cultivation strategies like optimization of inlet gas composition (in terms of % (v/v) O(2) in air), air-flow rate and addition of oxygen vectors in the medium, to curb the oxygen transfer limitations during hairy root cultivation of Azadirachta indica for in vitro azadirachtin (a biopesticide) production. It was found that increasing the oxygen fraction in the inlet air (in the range, 20-100% (v/v) O(2) in air) increased the azadirachtin productivity by approximately threefold, to a maximum of 4.42 mg/L per day (at 100% (v/v) O(2) in air) with respect to 1.68 mg/L per day in control (air with no oxygen supplementation). Similarly, increasing the air-flow rate (in the range, 0.3-2 vvm) also increased the azadirachtin productivity to a maximum of 1.84 mg/L per day at 0.8 vvm of air-flow rate. On the contrary, addition of oxygen vectors (in the range, 1-4% (v/v); hydrogen peroxide, toluene, Tween 80, kerosene, silicone oil, and n-hexadecane), decreased the azadirachtin productivity with respect to control (1.76 mg/L per day).

  3. Study of the irreversible trapping of dihydrogen with the use of a MnO2/Ag2O mixture

    International Nuclear Information System (INIS)

    Galliez, K.

    2012-01-01

    The hydrogen risk generated by radiolysis of organic compounds during a nuclear waste transport is a major issue. The use of irreversible getters is considered to limit this risk. The aim of this work is to study one of these getters, MnO 2 /Ag 2 O, in order to better understand the trapping phenomenon and to ensure its reliability. Initially several parameters affecting the trapping kinetics were studied. It has been shown that among all MnO 2 allotropic phases, the nsutite has the best trapping kinetics. Moreover, specific surface area and defect amount in MnO 2 can enhance trapping performances. Ag 2 O weight percentage (acting as promotor) has been determined at 13% to have the best trapping kinetics. Chemisorption of H 2 , which is required for its application, has been shown by using several characterization techniques such as magnetometry, infrared spectroscopy and electronic energy loss spectroscopy. The trapping irreversibility and the regeneration of the getter have been demonstrated respectively under nitrogen or air at 150 C. Finally, proton insertion mechanism in MnO 2 has been elucidated by pairs distribution function analysis through the development of a model to simulate the complex structure of MnO 2 . It has been shown that Ag 2 O is turned into Ag 2 CO 3 during the preparation of the getter under water, which has never been demonstrated. (author) [fr

  4. Thermomagnetic behaviour and compositional irreversibility on (Fe/Si)3 multilayer films

    International Nuclear Information System (INIS)

    Badía-Romano, L.; Rubín, J.; Magén, C.; Bartolomé, F.; Sesé, J.; Ibarra, M.R.; Bartolomé, J.

    2014-01-01

    This work presents the correlation between the morphology and magnetic properties of (Fe/Si) 3 multilayers with different Fe layer thicknesses and fixed Si spacer thickness in a broad temperature range (5 R /M S ratios and saturation fields are related to several types of interlayer exchange coupling. 90°-coupling and a superposition of 90° and antiferromagnetic interlayer exchange coupling are found depending on the Fe layer thickness. Magnetization curves were investigated as a function of temperature by in situ annealing. They show an irreversible thermal process as temperature increases from 300 to 450 K that is correlated to the formation of a ferromagnetic silicide phase. At higher temperature this phase transforms into a paramagnetic Fe–Si phase. - Highlights: • A thermomagnetic study on (Fe/Si) 3 multilayers is performed by in situ annealing. • We assess on the Fe layer thickness dependence, while the Si spacer is fixed. • 90° and AF interlayer exchange couplings are found depending on the Fe thickness. • We report an irreversible thermal process, correlated to chemical transformations. • The integrity of these (Fe/Si) 3 films is conserved just till T≈410K

  5. Which elements are involved in reversible and irreversible cartilage degradation in osteoarthritis?

    DEFF Research Database (Denmark)

    Bay-Jensen, Anne-Christine; Hoegh-Madsen, Suzi; Dam, Erik

    2010-01-01

    -physiology of the joint and whether the joint damage is reversible or irreversible. In this review, we compile emerging data on cellular and pathological aspects of OA, and ask whether these data could give clue to when cartilage degradation is reversible and whether a point-of-no-return exists. We highlight different...

  6. The incompressibility assumption in computational simulations of nasal airflow.

    Science.gov (United States)

    Cal, Ismael R; Cercos-Pita, Jose Luis; Duque, Daniel

    2017-06-01

    Most of the computational works on nasal airflow up to date have assumed incompressibility, given the low Mach number of these flows. However, for high temperature gradients, the incompressibility assumption could lead to a loss of accuracy, due to the temperature dependence of air density and viscosity. In this article we aim to shed some light on the influence of this assumption in a model of calm breathing in an Asian nasal cavity, by solving the fluid flow equations in compressible and incompressible formulation for different ambient air temperatures using the OpenFOAM package. At low flow rates and warm climatological conditions, similar results were obtained from both approaches, showing that density variations need not be taken into account to obtain a good prediction of all flow features, at least for usual breathing conditions. This agrees with most of the simulations previously reported, at least as far as the incompressibility assumption is concerned. However, parameters like nasal resistance and wall shear stress distribution differ for air temperatures below [Formula: see text]C approximately. Therefore, density variations should be considered for simulations at such low temperatures.

  7. Incidence of missed inferior alveolar nerve blocks in vital asymptomatic subjects and in patients with symptomatic irreversible pulpitis.

    Science.gov (United States)

    Fowler, Sara; Reader, Al; Beck, Mike

    2015-05-01

    The purpose of this retrospective study was to determine the incidence of missed inferior alveolar nerve (IAN) blocks by using a 1- or 2-cartridge volume of 2% lidocaine with 1:100,000 epinephrine in vital asymptomatic teeth and in emergency patients with symptomatic irreversible pulpitis. As part of 37 studies, 3169 subjects/patients were evaluated for missed IAN blocks. The study included 2450 asymptomatic subjects and 719 emergency patients presenting with symptomatic irreversible pulpitis. Each subject or patient received either a 1- or 2-cartridge volume of 2% lidocaine with 1:100,000 epinephrine. A missed block was defined as no lip numbness at 15-20 minutes after the IAN block. The effect of anesthetic volume on the incidence of missed blocks was assessed by using mixed models logistic regression with individual studies as a random effect. The incidence of missed blocks for asymptomatic subjects was 6.3% for the 1-cartridge volume and 3.8% for the 2-cartridge volume. For patients presenting with irreversible pulpitis, the incidence of missed blocks was 7.7% for the 1-cartridge volume and 2.3% for the 2-cartridge volume. In both asymptomatic subjects and patients with irreversible pulpitis, the 2-cartridge volume was significantly (P = .0395) better than the 1-cartridge volume. There were no significant effects for pulpal diagnosis (P = .7523) or the pulpal diagnosis and anesthetic volume interaction (P = .3973). Concerning missed IAN blocks, we concluded that administration of a 2-cartridge volume was significantly better (P = .0395) than a 1-cartridge volume in both asymptomatic subjects and emergency patients presenting with irreversible pulpitis. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Basic quantum irreversibility in neutron interferometry

    International Nuclear Information System (INIS)

    Rauch, H

    2009-01-01

    The transition between the quantum and classical world is a topical problem in quantum physics, which can be investigated by neutron interferometric methods. Here we discuss unavoidable quantum losses as they appear in neutron phase-echo and spin rotation experiments and we show how entanglement effects in a single-particle system demonstrate quantum contextuality, i.e. an entanglement between external and internal degrees of freedom in single-particle systems. This contextuality phenomenon also shows that a quantum system carries much more information than usually extracted. In all cases of an interaction, parasitic beams are produced which cannot be recombined completely with the original beam. This means that a complete reconstruction of the original state is, in principle, impossible which causes a kind of intrinsic irreversibility. Even small interaction potentials can have huge effects when they are applied in quantum Zeno-like experiments. The path towards advanced neutron quantum optics will be discussed.

  9. A relation between irreversibility and unlinkability for biometric template protection algorithms

    OpenAIRE

    井沼, 学

    2014-01-01

    For biometric recognition systems, privacy protection of enrolled users’ biometric information, which are called biometric templates, is a critical problem. Recently, various template protection algorithms have been proposed and many related previous works have discussed security notions to evaluate the protection performance of these protection algorithms. Irreversibility and unlinkability are important security notions discussed in many related previous works. In this paper, we prove that u...

  10. Competing irreversible cooperative reactions on polymer chains

    International Nuclear Information System (INIS)

    Evans, J.W.; Hoffman, D.K.; Burgess, D.R.

    1984-01-01

    We analyze model processes involving competition between several irreversible reactions at the sites of a 1D, infinite, uniform polymer chain. These reactions can be cooperative, i.e., the corresponding rates depend on the state of the surrounding sites. An infinite hierarchy of rate equations is readily derived for the probabilities of various subconfigurations. By exploiting a shielding property of suitable blocks of unreacted sites, we show how exact hierarchy truncation and solution is sometimes possible. The behavior of solutions is illustrated in several cases by plotting families of ''reaction trajectories'' for varying ratios of reactant concentrations. As a specific application, we consider competition between coordination of ZnCl 2 to pairs of oxygen atoms and to single oxygen atoms in poly(propylene oxide). The observed glass transition temperature behavior is eludicated

  11. Characterizing Time Irreversibility in Disordered Fermionic Systems by the Effect of Local Perturbations

    Science.gov (United States)

    Vardhan, Shreya; De Tomasi, Giuseppe; Heyl, Markus; Heller, Eric J.; Pollmann, Frank

    2017-07-01

    We study the effects of local perturbations on the dynamics of disordered fermionic systems in order to characterize time irreversibility. We focus on three different systems: the noninteracting Anderson and Aubry-André-Harper (AAH) models and the interacting spinless disordered t -V chain. First, we consider the effect on the full many-body wave functions by measuring the Loschmidt echo (LE). We show that in the extended or ergodic phase the LE decays exponentially fast with time, while in the localized phase the decay is algebraic. We demonstrate that the exponent of the decay of the LE in the localized phase diverges proportionally to the single-particle localization length as we approach the metal-insulator transition in the AAH model. Second, we probe different phases of disordered systems by studying the time expectation value of local observables evolved with two Hamiltonians that differ by a spatially local perturbation. Remarkably, we find that many-body localized systems could lose memory of the initial state in the long-time limit, in contrast to the noninteracting localized phase where some memory is always preserved.

  12. Treatment planning of electroporation-based medical interventions: electrochemotherapy, gene electrotransfer and irreversible electroporation

    International Nuclear Information System (INIS)

    Zupanic, Anze; Kos, Bor; Miklavcic, Damijan

    2012-01-01

    In recent years, cancer electrochemotherapy (ECT), gene electrotransfer for gene therapy and DNA vaccination (GET) and tissue ablation with irreversible electroporation (IRE) have all entered clinical practice. We present a method for a personalized treatment planning procedure for ECT, GET and IRE, based on medical image analysis, numerical modelling of electroporation and optimization with the genetic algorithm, and several visualization tools for treatment plan assessment. Each treatment plan provides the attending physician with optimal positions of electrodes in the body and electric pulse parameters for optimal electroporation of the target tissues. For the studied case of a deep-seated tumour, the optimal treatment plans for ECT and IRE require at least two electrodes to be inserted into the target tissue, thus lowering the necessary voltage for electroporation and limiting damage to the surrounding healthy tissue. In GET, it is necessary to place the electrodes outside the target tissue to prevent damage to target cells intended to express the transfected genes. The presented treatment planning procedure is a valuable tool for clinical and experimental use and evaluation of electroporation-based treatments. (paper)

  13. Magnetic resonance measurement of turbulent kinetic energy for the estimation of irreversible pressure loss in aortic stenosis.

    Science.gov (United States)

    Dyverfeldt, Petter; Hope, Michael D; Tseng, Elaine E; Saloner, David

    2013-01-01

    The authors sought to measure the turbulent kinetic energy (TKE) in the ascending aorta of patients with aortic stenosis and to assess its relationship to irreversible pressure loss. Irreversible pressure loss caused by energy dissipation in post-stenotic flow is an important determinant of the hemodynamic significance of aortic stenosis. The simplified Bernoulli equation used to estimate pressure gradients often misclassifies the ventricular overload caused by aortic stenosis. The current gold standard for estimation of irreversible pressure loss is catheterization, but this method is rarely used due to its invasiveness. Post-stenotic pressure loss is largely caused by dissipation of turbulent kinetic energy into heat. Recent developments in magnetic resonance flow imaging permit noninvasive estimation of TKE. The study was approved by the local ethics review board and all subjects gave written informed consent. Three-dimensional cine magnetic resonance flow imaging was used to measure TKE in 18 subjects (4 normal volunteers, 14 patients with aortic stenosis with and without dilation). For each subject, the peak total TKE in the ascending aorta was compared with a pressure loss index. The pressure loss index was based on a previously validated theory relating pressure loss to measures obtainable by echocardiography. The total TKE did not appear to be related to global flow patterns visualized based on magnetic resonance-measured velocity fields. The TKE was significantly higher in patients with aortic stenosis than in normal volunteers (p < 0.001). The peak total TKE in the ascending aorta was strongly correlated to index pressure loss (R(2) = 0.91). Peak total TKE in the ascending aorta correlated strongly with irreversible pressure loss estimated by a well-established method. Direct measurement of TKE by magnetic resonance flow imaging may, with further validation, be used to estimate irreversible pressure loss in aortic stenosis. Copyright © 2013 American

  14. Voter model with arbitrary degree dependence: clout, confidence and irreversibility

    Science.gov (United States)

    Fotouhi, Babak; Rabbat, Michael G.

    2014-03-01

    The voter model is widely used to model opinion dynamics in society. In this paper, we propose three modifications to incorporate heterogeneity into the model. We address the corresponding oversimplifications of the conventional voter model which are unrealistic. We first consider the voter model with popularity bias. The influence of each node on its neighbors depends on its degree. We find the consensus probabilities and expected consensus times for each of the states. We also find the fixation probability, which is the probability that a single node whose state differs from every other node imposes its state on the entire system. In addition, we find the expected fixation time. Then two other extensions to the model are proposed and the motivations behind them are discussed. The first one is confidence, where in addition to the states of neighbors, nodes take their own state into account at each update. We repeat the calculations for the augmented model and investigate the effects of adding confidence to the model. The second proposed extension is irreversibility, where one of the states is given the property that once nodes adopt it, they cannot switch back. This is motivated by applications where, agents take an irreversible action such as seeing a movie, purchasing a music album online, or buying a new product. The dynamics of densities, fixation times and consensus times are obtained.

  15. Influence of staircase ventilation state on the airflow and heat transfer of the heated room on the middle floor of high rise building

    International Nuclear Information System (INIS)

    Shi, W.X.; Ji, J.; Sun, J.H.; Lo, S.M.; Li, L.J.; Yuan, X.Y.

    2014-01-01

    Highlights: • Experiments are conducted in a scaled building model. • The flow and heat transfer in the heated room are investigated. • The staircase ventilation state influence on the heated room. • The results are useful to understand the safety and energy efficiency of building. - Abstract: Safety and energy efficiency of high rise buildings have attracted public attention in recent decades. In this paper, a set of experiments was conducted in a scaled building model with 12 floors to study the influence of the staircase ventilation state on the flow and heat transfer of the heated room on the middle floor. The airflow, room temperature and fuel burning rate were investigated. It is found that when the window above the heated room is opened, the vents state below the heated room has a significant effect on the airflow and heat transfer in the heated room. When the vents below the heated room are closed, the single-directional air flows into the heated room owing to the stronger stack effect. And the flame tilt angle is larger and the upper hot smoke temperature in the heated room is low. However, when the windows above the heated room are closed, the vents state below the heated room has little influence on the airflow and heat transfer in the heated room. And, there is two-directional air flowing through the door of the heated room The burning rate of heat source is also affected by the staircase ventilation state, and the variation trend varies with the opened window position and pool size

  16. Constructal theory through thermodynamics of irreversible processes framework

    International Nuclear Information System (INIS)

    Tescari, S.; Mazet, N.; Neveu, P.

    2011-01-01

    Highlights: → Point to area flow problem is solved through Thermodynamics of irreversible processes. → A new optimisation criterion is defined: the exergy or entropy impedance. → Optimisation is performed following two different routes, constructal or global. → Global optimisation is more efficient than constructal optimisation. → Global optimisation enhances the domain of construct benefits. - Abstract: Point to volume flow problem is revisited on a thermodynamics of irreversible processes (TIP) basis. The first step consists in evaluating the local entropy production of the system, and deducing from this expression the phenomenological laws. Then, the total entropy production can be simply evaluated. It is demonstrated that total entropy production can be written in a remarkable form: the product of the so-called entropy impedance with the square of the heat flux. As the heat flux is given, optimisation consists in minimising the entropy impedance. It is also shown that minimising entropy impedance minimises the maximum temperature difference. Applied to the elemental volume, this optimisation process leads to a shape factor close to the one already published. For the first construction, the equivalent system is defined as stated by Prigogine: when subjected to the same constraints, two systems are thermodynamically equivalent if their entropy production is equal. Two optimisation routes are then investigated: a global optimisation where all scales are taken into account and the constructal optimisation where the system is optimised scale by scale. In this second case, results are close to Ghodossi's work. When global optimisation is performed, it is demonstrated that conductive paths have to be spread uniformly in the active material (i.e. the number of elemental volumes must go to infinite). Comparing the two routes, global optimisation leads to better performance than constructal optimisation. Moreover, global optimisation enlarges the domain of

  17. Performance analysis of irreversible molten carbonate fuel cell – Braysson heat engine with ecological objective approach

    International Nuclear Information System (INIS)

    Açıkkalp, Emin

    2017-01-01

    Highlights: • An irreversible MCFC - Braysson heat engine is considered. • Its performance is investigated with ecological approach. • A new ecological criteria are presented called as modified ecological function. • Result are obtained numerically and discussed. - Abstract: An irreversible hybrid molten carbonate fuel cell-Braysson heat engine is taken into account. Basic thermodynamics parameters including power output, efficiency and exergy destruction rate are considered. In addition ecological function and new criteria, which is based on ecological function, for heat engines called as modified ecological function is suggested. Optimum conditions for mentioned parameters above are determined. Numerical results are obtained and plotted. Finally, results are discussed.

  18. Characteristics of Turbulent Airflow Deduced from Rapid Surface Thermal Fluctuations: An Infrared Surface Anemometer

    Science.gov (United States)

    Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani

    2017-12-01

    The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.

  19. [Mineral trioxide aggragate pulpotomy for the treatment of immature permanent teeth with irreversible pulpitis: a preliminary clinical study].

    Science.gov (United States)

    Peng, Chufang; Zhao, Yuming; Yang, Yuan; Qin, Man

    2015-12-01

    To evaluate the preliminary clinical effect of mineral trioxide aggragate (MTA) pulpotomy on immature permanent teeth with irreversible pulpitis. Twenty-six immature permanent teeth with irreversible pulpitis were recuited from Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology. These teeth were treated with partial or full pulpotomy according to the condition of pulp bleeding. MTA was used as pulp capping material. Patients were recalled periodically after the treatment. Clinical and radiographic effects were evaluated. At one year follow-up, 20 teeth were evaluated as healed or healing, 2 teeth were evaluated as failure and 4 teeth were dropped out. The success rate was considered 91% (20/22). A dentinal bridge was radiographcally observed underneath the pulpotomy site in 13 teeth(65%, 13/20). MTA pulpotomy is an effective method for the treatment of immature permanent teeth with irreversible pulpitis. But further research with longer follow up period is required.

  20. Behavior of the irreversibility line in the new superconductor La{sub 1.5+x}Ba{sub 1.5+x-y}Ca{sub y}Cu{sub 3}O{sub z}

    Energy Technology Data Exchange (ETDEWEB)

    Parra Vargas, C.A. [Grupo de Fisica de Materiales, Escuela de Fisica, Universidad Pedagogica y Tecnologica de Colombia, Tunja (Colombia); Pimentel, J.L.; Pureur, P. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS (Brazil); Landinez Tellez, D.A. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 5997, Bogota DC (Colombia); Roa-Rojas, J., E-mail: carlos.parra@uptc.edu.co [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 5997, Bogota DC (Colombia)

    2012-08-15

    The irreversibility properties of high-T{sub c} superconductors are of major importance for technological applications. For example, a high irreversibility magnetic field is a more desirable quality for a superconductor . The irreversibility line in the H-T plane is constituted by experimental points, which divides the irreversible and reversible behavior of the magnetization. The irreversibility lines for series of La{sub 1.5+x}Ba{sub 1.5+x-y}Ca{sub y}Cu{sub 3}O{sub z} polycrystalline samples with different doping were investigated. The samples were synthesized using the usual solid estate reaction method. Rietveld-type refinement of x-ray diffraction patterns permitted to determine the crystallization of material in a tetragonal structure. Curves of magnetization ZFC-FC for the system La{sub 1.5+x}Ba{sub 1.5+x-y}Ca{sub y}Cu{sub 3}O{sub z}, were measured in magnetic fields of the 10-20,000 Oe, and allowed to obtain the values for the irreversibility and critical temperatures. The data of irreversibility temperature allowed demarcating the irreversibility line, T{sub irr}(H). Two main lines are used for the interpretation of the irreversibility line: one of those which suppose that the vortexes are activated thermally and the other proposes that associated to T{sub irr} a phase transition occurs. The irreversibility line is described by a power law. The obtained results allow concluding that in the system La{sub 1.5+x}Ba{sub 1.5+x-y}Ca{sub y}Cu{sub 3}O{sub z} a characteristic bend of the Almeida-Thouless (AT) tendency is dominant for low fields and a bend Gabay-Toulouse (GT) behavior for high magnetic fields. This feature of the irreversibility line has been reported as a characteristic of granular superconductors and it corroborates the topological effects of vortexes mentioned by several authors .

  1. Irreversibility of world-sheet renormalization group flow

    International Nuclear Information System (INIS)

    Oliynyk, T.; Suneeta, V.; Woolgar, E.

    2005-01-01

    We demonstrate the irreversibility of a wide class of world-sheet renormalization group (RG) flows to first order in α ' in string theory. Our techniques draw on the mathematics of Ricci flows, adapted to asymptotically flat target manifolds. In the case of somewhere-negative scalar curvature (of the target space), we give a proof by constructing an entropy that increases monotonically along the flow, based on Perelman's Ricci flow entropy. One consequence is the absence of periodic solutions, and we are able to give a second, direct proof of this. If the scalar curvature is everywhere positive, we instead construct a regularized volume to provide an entropy for the flow. Our results are, in a sense, the analogue of Zamolodchikov's c-theorem for world-sheet RG flows on noncompact spacetimes (though our entropy is not the Zamolodchikov C-function)

  2. Trigeminocardiac reflex during non-surgical root canal treatment of teeth with irreversible pulpitis

    Directory of Open Access Journals (Sweden)

    James I.-Sheng Huang

    2018-06-01

    Full Text Available Background/Purpose: Trigeminocardiac reflex (TCR is a unique clinical incident of acute change in hemodynamic balance, which may lead to hypotension, bradycardia, and even clinical crisis. Up to date, no study so far considers the impact of non-surgical root canal treatment (NSRCT of irreversible pulpitis teeth under either local infiltration or block anesthesia on hemodynamic change possibly related to TCR. Methods: This study enrolled 111 patients with 138 irreversible pulpitis teeth that were treated by two sessions of NSRCT. The first session involved mainly the removal of vital pulp tissue with the direct stimulation of the dental branches of the trigeminal nerve, and the second session included the root canal enlargement and debridement with minimal disturbance to the dental branches of the trigeminal nerve. Vital signs mainly the blood pressure were recorded during both NSRCT sessions. Results: The incidences of NSRCT patients with MABP decrease ≧10%, ≧15%, or ≧20% were all significantly higher in the first NSRCT session than in the second NSRCT session (all the P-values < 0.001. In the first NSRCT session, the incidence of patients with MABP decrease ≧10% was significantly associated with tooth type. For both upper and lower teeth, the patients with premolars treated by NSRCR had significantly higher incidences of MABP decrease ≧10% than those with either anterior or molar teeth treated by NSRCR (all the P-values < 0.05. Conclusion: We conclude that vital pulp extirpation may lead to a substantial drop in patient's blood pressure possibly related to TCR. Keywords: Trigeminocardiac reflex, Non-surgical root canal treatment, Irreversible pulpitis, Mean arterial blood pressure, Hypotension, Teeth

  3. Endothelial dysfunction and atherosclerosis in children with irreversible pulmonary hypertension due to congenital heart disease

    International Nuclear Information System (INIS)

    Çiftel, Murat; Şimşek, Ayse; Turan, Özlem; Kardelen, Firat; Akçurin, Gayaz; Ertuğ, Halil

    2012-01-01

    To assess endothelial dysfunction and the risk for coronary atherosclerosis in children with irreversible pulmonary hypertension due to congenital heart disease (CHD). The study included 18 cyanotic patients (the mean age was 12.28 ± 3.26 years) who developed irreversible pulmonary hypertension due to cyanotic and acyanotic CHDs, and 18 control patients (the mean age was 11.78 ± 3.00 years). Study groups were compared for flow-mediated dilatation (FMD), carotid intima media thickness (CIMT) and atherosclerotic risk factors. Compared to the control group, the mean FMD was significantly reduced in the cyanotic group (5.26 ± 2.42% and 9.48 ± 2.60%, respectively; P-value < 0.001). No significant difference was observed between the groups in CIMT (0.41 ± 0.08 mm and 0.39 ± 0.06 mm, respectively; P-value = 0.299). The levels of total cholesterol, low-density lipoprotein–cholesterol and very low-density lipoprotein–cholesterol were statistically significantly lower compared tothe control group (P-value = 0.001, 0.006 and 0.014, respectively), whereas no statistically significant difference was found in the levels of high-density lipoprotein–cholesterol and triglycerides (P-value = 0.113 and 0.975, respectively). Systemic endothelial dysfunction in children with irreversible pulmonary hypertension due to CHD was noted but there was no increased risk for atherosclerosis

  4. Irreversible dilation of NaCl contaminated lime-cement mortar due to crystallization cycles

    NARCIS (Netherlands)

    Lubelli, B.; van Hees, R.P.J.; Huinink, H.P.; Groot, C.J.W.P.

    2006-01-01

    The mechanism of damage occurring in NaCl contaminated materials has not been clarified yet. Apart from crystn. pressure, other hypotheses have been proposed to explain the cause of decay. Irreversible dilation has been obsd. in a few cases but has never been studied in a more systematic way. The

  5. Alpha 2-adrenergic receptor turnover in adipose tissue and kidney: irreversible blockade of alpha 2-adrenergic receptors by benextramine

    International Nuclear Information System (INIS)

    Taouis, M.; Berlan, M.; Lafontan, M.

    1987-01-01

    The recovery of post- and extrasynaptic alpha 2-adrenergic receptor-binding sites was studied in vivo in male golden hamsters after treatment with an irreversible alpha-adrenoceptor antagonist benextramine, a tetramine disulfide that possesses a high affinity for alpha 2-binding sites. The kidney alpha 2-adrenergic receptor number was measured with [ 3 H]yohimbine, whereas [ 3 H]clonidine was used for fat cell and brain membrane alpha 2-binding site identification. Benextramine treatment of fat cell, kidney, and brain membranes reduced or completely suppressed, in an irreversible manner, [ 3 H] clonidine and [ 3 H]yohimbine binding without modifying adenosine (A1-receptor) and beta-adrenergic receptor sites. This irreversible binding was also found 1 and 2 hr after intraperitoneal administration of benextramine to the hamsters. Although it bound irreversibly to peripheral and central alpha 2-adrenergic receptors on isolated membranes, benextramine was unable to cross the blood-brain barrier of the hamster at the concentrations used (10-20 mg/kg). After the irreversible blockade, alpha 2-binding sites reappeared in kidney and adipose tissue following a monoexponential time course. Recovery of binding sites was more rapid in kidney than in adipose tissue; the half-lives of the receptor were 31 and 46 hr, respectively in the tissues. The rates of receptor production were 1.5 and 1.8 fmol/mg of protein/hr in kidney and adipose tissue. Reappearance of alpha 2-binding sites was associated with a rapid recovery of function (antilipolytic potencies of alpha 2-agonists) in fat cells inasmuch as occupancy of 15% of [ 3 H]clonidine-binding sites was sufficient to promote 40% inhibition of lipolysis. Benextramine is a useful tool to estimate turnover of alpha 2-adrenergic receptors under normal and pathological situations

  6. Measuring OutdoorAir Intake Rates Using Electronic Velocity Sensors at Louvers and Downstream of Airflow Straighteners

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William; Sullivan, Douglas; Cohen, Sebastian; Han, Hwataik

    2008-10-01

    Practical and accurate technologies are needed for continuously measuring and controlling outdoor air (OA) intake rates in commercial building heating, ventilating, and air conditioning (HVAC) systems. This project evaluated two new measurement approaches. Laboratory experiments determined that OA flow rates were measurable with errors generally less than 10percent using electronic air velocity probes installed between OA intake louver blades or at the outlet face of louvers. High accuracy was maintained with OA flow rates as low as 15percent of the maximum for the louvers. Thus, with this measurement approach HVAC systems do not need separate OA intakes for minimum OA supply. System calibration parameters are required for each unique combination of louver type and velocity sensor location but calibrations are not necessary for each system installation. The research also determined that the accuracy of measuring OA flow rates with velocity probes located in the duct downstream of the intake louver was not improved by installing honeycomb airflow straighteners upstream of the probes. Errors varied with type of upstream louver, were as high as 100percent, and were often greater than 25percent. In conclusion, use of electronic air velocity probes between the blades of OA intake louvers or at the outlet face of louvers is a highly promising means of accurately measuring rates of OA flow into HVAC systems. The use of electronic velocity probes downstream of airflow straighteners is less promising, at least with the relatively small OA HVAC inlet systems employed in this research.

  7. Relationship between spontaneous expiratory flow-volume curve pattern and air-flow obstruction in elderly COPD patients.

    Science.gov (United States)

    Nozoe, Masafumi; Mase, Kyoshi; Murakami, Shigefumi; Okada, Makoto; Ogino, Tomoyuki; Matsushita, Kazuhiro; Takashima, Sachie; Yamamoto, Noriyasu; Fukuda, Yoshihiro; Domen, Kazuhisa

    2013-10-01

    Assessment of the degree of air-flow obstruction is important for determining the treatment strategy in COPD patients. However, in some elderly COPD patients, measuring FVC is impossible because of cognitive dysfunction or severe dyspnea. In such patients a simple test of airways obstruction requiring only a short run of tidal breathing would be useful. We studied whether the spontaneous expiratory flow-volume (SEFV) curve pattern reflects the degree of air-flow obstruction in elderly COPD patients. In 34 elderly subjects (mean ± SD age 80 ± 7 y) with stable COPD (percent-of-predicted FEV(1) 39.0 ± 18.5%), and 12 age-matched healthy subjects, we measured FVC and recorded flow-volume curves during quiet breathing. We studied the SEFV curve patterns (concavity/convexity), spirometry results, breathing patterns, and demographics. The SEFV curve concavity/convexity prediction accuracy was examined by calculating the receiver operating characteristic curves, cutoff values, area under the curve, sensitivity, and specificity. Fourteen subjects with COPD had a concave SEFV curve. All the healthy subjects had convex SEFV curves. The COPD subjects who had concave SEFV curves often had very severe airway obstruction. The percent-of-predicted FEV(1)% (32.4%) was the most powerful SEFV curve concavity predictor (area under the curve 0.92, 95% CI 0.83-1.00), and had the highest sensitivity (0.93) and specificity (0.88). Concavity of the SEFV curve obtained during tidal breathing may be a useful test for determining the presence of very severe obstruction in elderly patients unable to perform a satisfactory FVC maneuver.

  8. Topological properties of the limited penetrable horizontal visibility graph family

    Science.gov (United States)

    Wang, Minggang; Vilela, André L. M.; Du, Ruijin; Zhao, Longfeng; Dong, Gaogao; Tian, Lixin; Stanley, H. Eugene

    2018-05-01

    The limited penetrable horizontal visibility graph algorithm was recently introduced to map time series in complex networks. In this work, we extend this algorithm to create a directed-limited penetrable horizontal visibility graph and an image-limited penetrable horizontal visibility graph. We define two algorithms and provide theoretical results on the topological properties of these graphs associated with different types of real-value series. We perform several numerical simulations to check the accuracy of our theoretical results. Finally, we present an application of the directed-limited penetrable horizontal visibility graph to measure real-value time series irreversibility and an application of the image-limited penetrable horizontal visibility graph that discriminates noise from chaos. We also propose a method to measure the systematic risk using the image-limited penetrable horizontal visibility graph, and the empirical results show the effectiveness of our proposed algorithms.

  9. X-tip intraosseous injection system as a primary anesthesia for irreversible pulpitis of posterior mandibular teeth: A randomized clinical trail

    OpenAIRE

    Razavian, Hamid; Kazemi, Shantia; Khazaei, Saber; Jahromi, Maryam Zare

    2013-01-01

    Background: Successful anesthesia during root canal therapy may be difficult to obtain. Intraosseous injection significantly improves anesthesia′s success as a supplemental pulpal anesthesia, particularly in cases of irreversible pulpitis. The aim of this study was to compare the efficacy of X-tip intraosseous injection and inferior alveolar nerve (IAN) block in primary anesthesia for mandibular posterior teeth with irreversible pulpitis. Materials and Methods: Forty emergency patients wi...

  10. Performance evaluation of an irreversible Miller cycle comparing FTT (finite-time thermodynamics) analysis and ANN (artificial neural network) prediction

    International Nuclear Information System (INIS)

    Mousapour, Ashkan; Hajipour, Alireza; Rashidi, Mohammad Mehdi; Freidoonimehr, Navid

    2016-01-01

    In this paper, the first and second-laws efficiencies are applied to performance analysis of an irreversible Miller cycle. In the irreversible cycle, the linear relation between the specific heat of the working fluid and its temperature, the internal irreversibility described using the compression and expansion efficiencies, the friction loss computed according to the mean velocity of the piston and the heat-transfer loss are considered. The effects of various design parameters, such as the minimum and maximum temperatures of the working fluid and the compression ratio on the power output and the first and second-laws efficiencies of the cycle are discussed. In the following, a procedure named ANN is used for predicting the thermal efficiency values versus the compression ratio, and the minimum and maximum temperatures of the Miller cycle. Nowadays, Miller cycle is widely used in the automotive industry and the obtained results of this study will provide some significant theoretical grounds for the design optimization of the Miller cycle. - Highlights: • The performance of an irreversible Miller cycle is investigated using FFT. • The effects of design parameters on the performance of the cycle are investigated. • ANN is applied to predict the thermal efficiency and the power output values. • There is an excellent correlation between FTT and ANN data. • ANN can be applied to predict data where FTT analysis has not been performed.

  11. Irreversibility Curve on Y1–xLuxBa2Cu3O7–δ (x=0.4, 0.5 and 0.6) superconducting

    International Nuclear Information System (INIS)

    Grimaldos, J F Cepeda; Supelano G, I; Santos, A Sarmiento; Chiquillo, M V; Martínez B, D; Vargas, C A Parra

    2014-01-01

    The irreversibility line in the H–T plane divides the irreversible and reversible behaviour of the magnetization which is of importance for the characterization of high T c superconductors. In this work, we report the production of Y 1–X Lu X Ba 2 Cu 3 O 7–δ (X=0.4, 0.5 and 0.6) superconducting system using the usual solid state reaction method. The irreversibility line H–T plane for the Y 1–X Lu X Ba 2 Cu 3 O 7–δ polycrystalline sample was investigated. The curves of magnetization ZFC (cero field cooled)- FC (field cooled) were measured in magnetic fields between 100 Oe and 4000 Oe, and allowed to obtain the values for irreversibility and critical temperatures

  12. Evaporation of a volatile organic compound in a hygroscopic soil - influence of the airflow and its VOC vapour saturation

    OpenAIRE

    Naon , Bétaboalé; Benet , Jean-Claude; Cousin , Bruno; Cherblanc , Fabien; Chammari , Ali

    2013-01-01

    International audience; This article presents an experimental and theoretical study of VOC volatilization in soil during a decontamination process by vapour extraction or venting. A phase change law is proposed in the case of a sandy-silty soil when the convective gaseous phase is vapour-charged. A simple experimental method for analyzing the phase change is presented. Finally, an efficiency coefficient is introduced to quantify the contribution of airflow velocity on venting.

  13. Loschmidt echo in many-spin systems: a quest for intrinsic decoherence and emergent irreversibility

    Science.gov (United States)

    Zangara, Pablo R.; Pastawski, Horacio M.

    2017-03-01

    If a magnetic polarization excess is locally injected in a crystal of interacting spins in thermal equilibrium, this ‘excitation’ would spread as consequence of spin-spin interactions. Such an apparently irreversible process is known as spin diffusion and it can lead the system back to ‘equilibrium’. Even so, a unitary quantum dynamics would ensure a precise memory of the non-equilibrium initial condition. Then, if at a certain time, say t/2, an experimental protocol reverses the many-body dynamics by changing the sign of the effective Hamiltonian, it would drive the system back to the initial non-equilibrium state at time t. As a matter of fact, the reversal is always perturbed by small experimental imperfections and/or uncontrolled internal or environmental degrees of freedom. This limits the amount of signal M(t) recovered locally at time t. The degradation of M(t) accounts for these perturbations, which can also be seen as the sources of decoherence. This general idea defines the Loschmidt echo (LE), which embodies the various time-reversal procedures implemented in nuclear magnetic resonance. Here, we present an invitation to the study of the LE following the pathway induced by the experiments. With such a purpose, we provide a historical and conceptual overview that briefly revisits selected phenomena that underlie the LE dynamics including chaos, decoherence, localization and equilibration. This guiding thread ultimately leads us to the discussion of decoherence and irreversibility as an emergent phenomenon. In addition, we introduce the LE formalism by means of spin-spin correlation functions in a manner suitable for presentation in a broad scope physics journal. Last, but not least, we present new results that could trigger new experiments and theoretical ideas. In particular, we propose to transform an initially localized excitation into a more complex initial state, enabling a dynamically prepared LE. This induces a global definition of the LE in

  14. Monopolistic pricing power for transgenic crops when technology adopters face irreversible benefits and costs

    NARCIS (Netherlands)

    Weaver, R.D.; Wesseler, J.H.H.

    2004-01-01

    Pricing of biotechnology innovation under a patent grant is reconsidered in a model with uncertain returns and irreversible costs and benefits. Past results oil restricted monopoly pricing in the presence of competing technologies showed that pricing power is reduced. The timing of adoption of an

  15. Chemical kinetics, stochastic processes, and irreversible thermodynamics

    CERN Document Server

    Santillán, Moisés

    2014-01-01

    This book brings theories in nonlinear dynamics, stochastic processes, irreversible thermodynamics, physical chemistry, and biochemistry together in an introductory but formal and comprehensive manner.  Coupled with examples, the theories are developed stepwise, starting with the simplest concepts and building upon them into a more general framework.  Furthermore, each new mathematical derivation is immediately applied to one or more biological systems.  The last chapters focus on applying mathematical and physical techniques to study systems such as: gene regulatory networks and ion channels. The target audience of this book are mainly final year undergraduate and graduate students with a solid mathematical background (physicists, mathematicians, and engineers), as well as with basic notions of biochemistry and cellular biology.  This book can also be useful to students with a biological background who are interested in mathematical modeling, and have a working knowledge of calculus, differential equatio...

  16. Unravelling the origin of irreversible capacity loss in NaNiO 2 for high voltage sodium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liguang; Wang, Jiajun; Zhang, Xiaoyi; Ren, Yang; Zuo, Pengjian; Yin, Geping; Wang, Jun

    2017-04-01

    Layered transition metal compounds have attracted much attention due to their high theoretical capacity and energy density for sodium ion batteries. However, this kind of material suffers from serious irreversible capacity decay during the charge and discharge process. Here, using synchrotron-based operando transmission X-ray microscopy and high-energy X-ray diffraction combined with electrochemical measurements, the visualization of the dissymmetric phase transformation and structure evolution mechanism of layered NaNiO2 material during initial charge and discharge cycles are clarified. Phase transformation and deformation of NaNiO2 during the voltage range of below 3.0 V and over 4.0 V are responsible for the irreversible capacity loss during the first cycling, which is also confirmed by the evolution of reaction kinetics behavior obtained by the galvanostatic intermittent titration technique. These findings reveal the origin of the irreversibility of NaNiO2 and offer valuable insight into the phase transformation mechanism, which will provide underlying guidance for further development of high-performance sodium ion batteries.

  17. Comprehensive performance analyses and optimization of the irreversible thermodynamic cycle engines (TCE) under maximum power (MP) and maximum power density (MPD) conditions

    International Nuclear Information System (INIS)

    Gonca, Guven; Sahin, Bahri; Ust, Yasin; Parlak, Adnan

    2015-01-01

    This paper presents comprehensive performance analyses and comparisons for air-standard irreversible thermodynamic cycle engines (TCE) based on the power output, power density, thermal efficiency, maximum dimensionless power output (MP), maximum dimensionless power density (MPD) and maximum thermal efficiency (MEF) criteria. Internal irreversibility of the cycles occurred during the irreversible-adiabatic processes is considered by using isentropic efficiencies of compression and expansion processes. The performances of the cycles are obtained by using engine design parameters such as isentropic temperature ratio of the compression process, pressure ratio, stroke ratio, cut-off ratio, Miller cycle ratio, exhaust temperature ratio, cycle temperature ratio and cycle pressure ratio. The effects of engine design parameters on the maximum and optimal performances are investigated. - Highlights: • Performance analyses are conducted for irreversible thermodynamic cycle engines. • Comprehensive computations are performed. • Maximum and optimum performances of the engines are shown. • The effects of design parameters on performance and power density are examined. • The results obtained may be guidelines to the engine designers

  18. Comparison of turbulence models for numerical calculation of airflow in an annex 20 room

    DEFF Research Database (Denmark)

    Voigt, Lars P. K.

    2000-01-01

    The report deals with 2-D numerical calculation of room airflow in an isothermal annex 20 room. The report documents the ability of the flow solver EllipSys2D to give results in good agreement with measurements for the specified test case. The flow solver is a finite volume code solving the Reyno.......Applying theory for a two-dimensional wall jet, measurements are compared with calculated values of the turbulent kinetic energy....... the Reynolds Averaged Navier Stokes equations.Five two-equation turbulence models were tested. These are the standard k-epsilon model, the low-Reynolds number k-epison model by Launder & Sharma, the k-omega model by Wilcox, the k-omega baseline (BSL) model by Menter and the k-omega Shear Stress Transport (SST...

  19. The relationship between lung function impairment and quantitative computed tomography in chronic obstructive pulmonary disease

    International Nuclear Information System (INIS)

    Mets, O.M.; Murphy, K.; Zanen, P.; Lammers, J.W.; Gietema, H.A.; Jong, P.A. de; Ginneken, B. van; Prokop, M.

    2012-01-01

    To determine the relationship between lung function impairment and quantitative computed tomography (CT) measurements of air trapping and emphysema in a population of current and former heavy smokers with and without airflow limitation. In 248 subjects (50 normal smokers; 50 mild obstruction; 50 moderate obstruction; 50 severe obstruction; 48 very severe obstruction) CT emphysema and CT air trapping were quantified on paired inspiratory and end-expiratory CT examinations using several available quantification methods. CT measurements were related to lung function (FEV 1 , FEV 1 /FVC, RV/TLC, Kco) by univariate and multivariate linear regression analysis. Quantitative CT measurements of emphysema and air trapping were strongly correlated to airflow limitation (univariate r-squared up to 0.72, p < 0.001). In multivariate analysis, the combination of CT emphysema and CT air trapping explained 68-83% of the variability in airflow limitation in subjects covering the total range of airflow limitation (p < 0.001). The combination of quantitative CT air trapping and emphysema measurements is strongly associated with lung function impairment in current and former heavy smokers with a wide range of airflow limitation. (orig.)

  20. Putative Stem Cells in Human Dental Pulp with Irreversible Pulpitis-An Exploratory Study

    Science.gov (United States)

    Wang, Z.; Pan, J.; Wright, JT; Bencharit, S.; Zhang, S.; Everett, ET; Teixeira, FB; Preisser, JS

    2010-01-01

    Introduction Although human dental pulp stem cells isolated from healthy teeth have been extensively characterized, it is unknown whether stem cells also exist in clinically compromised teeth with irreversible pulpitis. Here we explored whether cells retrieved from clinically compromised dental pulp have stem cell-like properties. Methods Pulp cells were isolated from healthy teeth (control group) and from teeth with clinically diagnosed irreversible pulpitis (diseased group). Cell proliferation, stem cell marker STRO-1 expression and cell odonto-osteo-genic differentiation competence were compared. Results Cells from the diseased group demonstrated decreased colony formation capacity and a slightly decreased cell proliferation rate but had similar STRO-1 expression, and exhibited a similar percentage of positive ex vivo osteogenic induction and dentin sialophosphoprotein expression from STRO-1-enriched pulp cells. Conclusion Our study provides preliminary evidence that clinically compromised dental pulp may contain putative cells with certain stem cell properties. Further characterization of these cells will provide insight regarding whether they could serve as a source of endogenous multipotent cells in tissue regeneration based dental pulp therapy. PMID:20416426