RESEARC H Open Access Decline in air pollution and change in prevalence in respiratory symptoms and chronic obstructive pulmonary disease in elderly women Tamara Schikowski 1,2,3* , Ulrich Ranft 1 , Dorothee Sugiri 1 , Andrea Vierkötter 1 , Thomas Brüning 4 , Volker Harth 4 , Ursula Krämer 1 Abstract Background: While adverse effects of exposure to air pollutants on respiratory health are well studied, little is known about the effect of a reduction in air pollutants on chronic respiratory symptoms and diseases. We investigated whether different declines in air pollution levels in industrialised and rural areas in Germany were associated with changes in respiratory health over a period of about 20 years. Methods: We used data from the SALIA cohort study in Germany (Study on the influence of Air pollution on Lung function, Inflammation and Aging) to assess the association between the prevalence of chronic obstructive pulmonary disease (COPD) and chronic respiratory symptoms and the decline in air pollution exposure. In 1985- 1994, 4874 women aged 55-years took part in the baseline investigation. Of these, 2116 participated in a questionnaire follow-up in 2006 and in a subgroup of 402 women lung function was tested in 2008-2009. Generalized estimating equation (GEE) models were used to estimate the effect of a reduction in air pollution on respiratory symptoms and diseases. Results: Ambient air concentrations of particulate matter with aerodynamic size < 10 μm (PM 10 ) declined in average by 20 μg/m 3 . Prevalence of chronic cough with phlegm production and mild COPD at baseline investigation compared to follow-up was 9.5% vs. 13.3% and 8.6% vs. 18.2%, respectively. A steeper decline of PM 10 was observed in the industrialized areas in comparison to the rural area, this was associated with a weaker increase in prevalence of respiratory symptoms and COPD. Among women who never smoked, the prevalence of chronic cough with phlegm and mild COPD was estimated at 21.4% and 39.5%, respectively, if no air pollution reduction was assumed, and at 13.3% and 17.5%, respectively, if air pollution reduction was assumed. Conclusion: We concluded that parallel to the decline of ambient air pollution over the last 20 years in the Ruhr area the age-related increase in chronic respiratory diseases and symptoms appears to attenuate in the population of elderly women. Introduction Several epidemiological studies have shown that chronic exposure to high levels of air poll utants (PM 10 and NO 2 ) has adverse effects on r espiratory health. These adverse effects on respiratory health are not limited to high concentrations of air pollutants, but have also been observed at relatively low concentrations. It has been previously reported that long-term exposure to air pol- lutan ts from traffic related sources reduce lung fu nction [1-5] and influence chronic respiratory diseases [6-8]. Furthermore, long-term exposure to air pollutants is known to be associated with cardiovascular mortality [9-12] and increased hospital admissions [13-16]. However, less is known about the effect of a reduction in air pollutants on chronic respiratory symptoms and diseases, including chronic cough. Chronic cough is common in Modifications in Respiratory Functions Modifications in Respiratory Functions Bởi: OpenStaxCollege At rest, the respiratory system performs its functions at a constant, rhythmic pace, as regulated by the respiratory centers of the brain At this pace, ventilation provides sufficient oxygen to all the tissues of the body However, there are times that the respiratory system must alter the pace of its functions in order to accommodate the oxygen demands of the body Hyperpnea Hyperpnea is an increased depth and rate of ventilation to meet an increase in oxygen demand as might be seen in exercise or disease, particularly diseases that target the respiratory or digestive tracts This does not significantly alter blood oxygen or carbon dioxide levels, but merely increases the depth and rate of ventilation to meet the demand of the cells In contrast, hyperventilation is an increased ventilation rate that is independent of the cellular oxygen needs and leads to abnormally low blood carbon dioxide levels and high (alkaline) blood pH Interestingly, exercise does not cause hyperpnea as one might think Muscles that perform work during exercise increase their demand for oxygen, stimulating an increase in ventilation However, hyperpnea during exercise appears to occur before a drop in oxygen levels within the muscles can occur Therefore, hyperpnea must be driven by other mechanisms, either instead of or in addition to a drop in oxygen levels The exact mechanisms behind exercise hyperpnea are not well understood, and some hypotheses are somewhat controversial However, in addition to low oxygen, high carbon dioxide, and low pH levels, there appears to be a complex interplay of factors related to the nervous system and the respiratory centers of the brain First, a conscious decision to partake in exercise, or another form of physical exertion, results in a psychological stimulus that may trigger the respiratory centers of the brain to increase ventilation In addition, the respiratory centers of the brain may be stimulated through the activation of motor neurons that innervate muscle groups that are involved in the physical activity Finally, physical exertion stimulates proprioceptors, which are 1/5 Modifications in Respiratory Functions receptors located within the muscles, joints, and tendons, which sense movement and stretching; proprioceptors thus create a stimulus that may also trigger the respiratory centers of the brain These neural factors are consistent with the sudden increase in ventilation that is observed immediately as exercise begins Because the respiratory centers are stimulated by psychological, motor neuron, and proprioceptor inputs throughout exercise, the fact that there is also a sudden decrease in ventilation immediately after the exercise ends when these neural stimuli cease, further supports the idea that they are involved in triggering the changes of ventilation High Altitude Effects An increase in altitude results in a decrease in atmospheric pressure Although the proportion of oxygen relative to gases in the atmosphere remains at 21 percent, its partial pressure decreases ([link]) As a result, it is more difficult for a body to achieve the same level of oxygen saturation at high altitude than at low altitude, due to lower atmospheric pressure In fact, hemoglobin saturation is lower at high altitudes compared to hemoglobin saturation at sea level For example, hemoglobin saturation is about 67 percent at 19,000 feet above sea level, whereas it reaches about 98 percent at sea level Partial Pressure of Oxygen at Different Altitudes Example location Atmospheric Altitude (feet pressure (mm above sea level) Hg) Partial pressure of oxygen (mm Hg) New York City, New York 760 159 Boulder, Colorado 5000 632 133 Aspen, Colorado 8000 565 118 Pike’s Peak, Colorado 14,000 447 94 Denali (Mt McKinley), Alaska 20,000 350 73 Mt Everest, Tibet 29,000 260 54 As you recall, partial pressure is extremely important in determining how much gas can cross the respiratory membrane and enter the blood of the pulmonary capillaries A lower partial pressure of oxygen means that there is a smaller difference in partial pressures between the alveoli and the blood, so less oxygen crosses the respiratory membrane As a result, fewer oxygen molecules are bound by hemoglobin Despite this, the tissues of the body still receive a sufficient amount of oxygen during rest at high altitudes This is due to two major mechanisms First, the number of oxygen molecules 2/5 Modifications in Respiratory Functions that enter the tissue from the blood is nearly equal between sea level and high altitudes At sea level, hemoglobin saturation is higher, but only a quarter of the oxygen molecules are actually released into the tissue At high altitudes, a greater proportion of molecules of oxygen are released into the tissues Secondly, at high altitudes, a greater amount of BPG is produced by erythrocytes, which enhances the dissociation of oxygen from ...A PROPOSAL FOR MODIFICATIONS IN THE FORMALISM OF GPSG James Kilbury Universit~t~Trier, FB II: LDV Postfach 3825, D-5500 Trier Fed. Rep. of Germany ABSTRACT Recent investigations show a remarkable conver- gence among contemporary unification-based formal- isms for syntactic description. This convergence is now itself becoming an object of study, and there is an increasing recognition of the need for explicit characterizations of the properties that relate and distinguish similar grammar formalisms. The paper proposes a series of changes in the for- malism of Generalized Phrase Structure Grammar that throw light on its relation to Functional Unifica- tion Grammar. The essential contribution is a generalization of cooccurrence restrictions, which become the principal and unifying device of GPSG. Introducing Category Cooccurrence Restrictions (CCRs) for lo- cal trees (in analogy to Feature Cooccurrence Re- strictions for categories) provides a genuine gain in expressiveness for the formalism. Other devices, such as Feature Instantiation Principles and Linear Precedence Statements can be regarded as special cases of CCRs. The proposals lead to a modified no- tion of unification itself. A PROPOSAL FOR MODIFICATIONS IN THE FORMALISM OF GPSG Recent investigations show a remarkable conver- gence among contemporary unification-based formal- isms for syntactic description (cf Shieber 1985). This convergence is now itself becoming an object of study, and there is an increasing recognition of the need for explicit characterizations of the properties that relate and distinguish similar grammar formalisms. For example, Shieber (1986) describes a compilation from Generalized Phrase Structure Grammar (GPSG; cf Gazdar et alii 1985, henceforth GKPS) to PATR-II. The compilation de- fines the semantics of GPSG by explicitly relating the two formalisms; at the same time, difficulties in specifying the compilation show that differ- ences between the formalisms transcend variety in notation. This paper is similar to Shieber's in its aim but differs in the approach. A series of changes in the formalism of GPSG will be proposed that make it look more like the "tool oriented" formal- ism of Functional Unification Grammar (FUG; cf Kay 1984 and Shieber 1985). This notational transfor- mation has two consequences: the essential and nonessential differences between GPSG and FUG can be made more apparent, and the internal structure of GPSG itself becomes more homogeneous and trans- parent. The homogeneity of a formalism is desirable on methodological grounds that amount to Occam's principle of economy: entities should not be mul- tiplied. This is not to suggest that linguistic formalisms can be simplified at our will; on the contrary, they must be complex and expressive enough to capture the complexities inherent in language itself. The burden of proof, however, falls on those who choose more complicated and heterogeneous notational devices. Despite its restrictiveness in comparison with current transformational theory, GPSG in the GKPS version offers a rich palette of formal devices. It introduces Feature Cooccurrence Restrictions (FCRs) to state Boolean restrictions on the co- occurrence of feature specifications within cate- gories but does not explore the use of analogous restrictions in other parts of the formalism. Im- mediate Dominance rules, metarules, and lexical rules are clearly distinguished in their form but all serve to capture the phenomenon of subcategor- ization. This paper proposes the extension of cooccur- rence restrictions in GPSG to express constraints on the cooccurrence of categories within local trees. While presented in Kilbury (1986) as a new descriptive device, such Category Cooccurrence Restrictions (CCRs) are in fact simply This PDF is a selection from an out-of-print volume from the National Bureau of Economic Research Volume Title: Education, Income, and Human Capital Volume Author/Editor: W. Lee Hansen, ed. Volume Publisher: UMI Volume ISBN: 0-870-14218-6 Volume URL: http://www.nber.org/books/hans70-1 Publication Date: 1970 Chapter Title: NOTES ON THE ROLE OF EDUCATION IN PRODUCTION FUNCTIONS AND GROWTH ACCOUNTING Chapter Author: Zvi Griliches Chapter URL: http://www.nber.org/chapters/c3277 Chapter pages in book: (p. 71 - 128) NOTES ON THE ROLE OF EDUCATION IN PRODUCTiON FUNCTIONS AND GROWTH ACCOUNTING • ZVI GRILICHES HARVARD UNIVERSITY I INTRODUCTION THIS paper started out as a survey of the uses of "education" variables in aggregate production functions and of the problems associated with the measurement of such variables and with the specification and esti- mation of models that use them. It soon became clear that some of the issues to be investigated (e.g., the relative contributions of ability and schooling to a labor quality index) were very complex and possessed a literature of such magnitude that any "quick" survey of it would be both • superficial and inadvisable. This paper, therefore, is in the fonn of a • } progress report on this survey, containing also a list of questions which this literature and future work may help eventually to elucidate. Not all • of the interesting questions will be asked, however, nor all of the pos- sible problems raised. I have limited myself to those areas which seem to require the most immediate attention as we proceed beyond the work already accomplished. As it currently stands, this paper first recapitulates and brings up to date the construction of a "quality of labor" index based on the changing distribution of the U. S. labor force by years of school completed. It then Nom: The work on this paper has been supported by National Science Foun- dation Grants Nos. GS 712 and OS 2026X. I am indebted to C. A. Anderson, Mary Jean Bowman, E. F. Denison, R. J. Gordon, and T. W. Schultz for comments and suggestions. 71 72 EDUCATION AND PRODUCTION FUNCTIONS surveys several attempts to "validate" such an index through the esti- mation of aggregate production functions and reviews some alternative approaches suggested in the literature. Next, the question of how many "dimensions" of labor it is useful to distinguish is raised and explored briefly. The puzzle of the apparent constancy of rates of return to edu- cation and of skilled-unskilled wage differentials in the last two decades provides a unifying thread through the latter parts of this paper as the discussion turns to the implications of the ability-education-income inter- relationships for the assessment of the contribution of education to growth, the possible sources of the differential growth in the demand for educated versus uneducated labor, and the possible complementarities between the accumulation of physical and human capital. While many questions are raised, only a few are answered. II THE QUALITY OF LABOR AND GROWTH ACCOUNTING ONE of the earliest responses to the appearance of a large "residual" in the works BioMed Central Page 1 of 11 (page number not for citation purposes) Journal of NeuroEngineering and Rehabilitation Open Access Research Using an electrohydraulic ankle foot orthosis to study modifications in feedforward control during locomotor adaptation to force fields applied in stance Martin Noel †1 , Karine Fortin †1 and Laurent J Bouyer* 1,2 Address: 1 Center for interdisciplinary research in rehabilitation and social integration (CIRRIS), Quebec City, Canada and 2 Department of Rehabilitation, Université Laval, Canada Email: Martin Noel - martin.noel.4@ulaval.ca; Karine Fortin - karine.fortin.6@ulaval.ca; Laurent J Bouyer* - laurent.bouyer@rea.ulaval.ca * Corresponding author †Equal contributors Abstract Background: Adapting to external forces during walking has been proposed as a tool to improve locomotion after central nervous system injury. However, sensorimotor integration during walking varies according to the timing in the gait cycle, suggesting that adaptation may also depend on gait phases. In this study, an ElectroHydraulic AFO (EHO) was used to apply forces specifically during mid-stance and push-off to evaluate if feedforward movement control can be adapted in these 2 gait phases. Methods: Eleven healthy subjects walked on a treadmill before (3 min), during (5 min) and after (5 min) exposure to 2 force fields applied by the EHO (mid-stance/push-off; ~10 Nm, towards dorsiflexion). To evaluate modifications in feedforward control, strides with no force field ('catch strides') were unexpectedly inserted during the force field walking period. Results: When initially exposed to a mid-stance force field (FF 20% ), subjects showed a significant increase in ankle dorsiflexion velocity. Catches applied early into the FF 20% were similar to baseline (P > 0.99). Subjects gradually adapted by returning ankle velocity to baseline over ~50 strides. Catches applied thereafter showed decreased ankle velocity where the force field was normally applied, indicating the presence of feedforward adaptation. When initially exposed to a push-off force field (FF 50% ), plantarflexion velocity was reduced in the zone of force field application. No adaptation occurred over the 5 min exposure. Catch strides kinematics remained similar to control at all times, suggesting no feedforward adaptation. As a control, force fields assisting plantarflexion (-3.5 to -9.5 Nm) were applied and increased ankle plantarflexion during push-off, confirming that the lack of kinematic changes during FF 50% catch strides were not simply due to a large ankle impedance. Conclusion: Together these results show that ankle exoskeletons such as the EHO can be used to study phase-specific adaptive control of the ankle during locomotion. Our data suggest that, for short duration exposure, a feedforward modification in torque output occurs during mid-stance but not during push-off. These findings are important for the design of novel rehabilitation methods, as they suggest that the ability to use resistive force fields for training may depend on targeted gait phases. Published: 3 June 2009 Journal of NeuroEngineering and Rehabilitation 2009, 6:16 doi:10.1186/1743-0003-6-16 Received: 21 October 2008 Accepted: 3 June 2009 This article is available from: http://www.jneuroengrehab.com/content/6/1/16 © 2009 Noel et al; licensee This Provisional PDF corresponds to the article as it appeared upon acceptance. Fully formatted PDF and full text (HTML) versions will be made available soon. On the stability of a mixed type functional equation in generalized functions Advances in Difference Equations 2012, 2012:16 doi:10.1186/1687-1847-2012-16 Young-Su Lee (masuri@sogang.ac.kr) ISSN 1687-1847 Article type Research Submission date 18 November 2011 Acceptance date 16 February 2012 Publication date 16 February 2012 Article URL http://www.advancesindifferenceequations.com/content/2012/1/16 This peer-reviewed article was published immediately upon acceptance. It can be downloaded, printed and distributed freely for any purposes (see copyright notice below). For information about publishing your research in Advances in Difference Equations go to http://www.advancesindifferenceequations.com/authors/instructions/ For information about other SpringerOpen publications go to http://www.springeropen.com Advances in Difference Equations © 2012 Lee ; licensee Springer. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. On the stability of a mixed type functional equation in generalized functions Young-Su Lee Department of Mathematics, Sogang University, Seoul 121-741, Repu blic of Korea Email address: masuri@sogang.ac.kr Abstract We reformulate the following mixed type quadratic and additive functional eq ua- tion with n-independent variables 2f n i=1 x i + 1≤i,j≤n i=j f(x i − x j ) = (n + 1) n i=1 f(x i ) + (n − 1) n i=1 f(−x i ) as the equation for the spaces of generalized functions. Using the fundamental solution of the heat equation, we solve the general solution and prove the Hyers– Ulam stability of this equation in the spaces of tempered distributions and Fourier hyperfunctions. Keywords: quadratic functional equation; additive functional equation; stability; heat kernel; Gauss trans fo rm. Mathematics Subject Classification 2000: 39B82; 39B52. 1 1. Intro duction In 1940, Ulam [1] raised a question concerning the stability of group homomorphisms as follows: Let G 1 be a group and let G 2 be a metric group with the metric d(·, ·). Given ǫ > 0, does there exist a δ > 0 such that if a function h : G 1 → G 2 satisfies the inequality d(h(xy), h(x)h(y)) < δ for all x, y ∈ G 1 , then there exists a homomorphism H : G 1 → G 2 with d(h(x), H(x)) < ǫ for all x ∈ G 1 ? In 1941, Hyers [2] firstly presented the stability result of functional equations under the assumption that G 1 and G 2 are Banach spaces. In 1978 , Rassias [3] generalized Hyers’ result to the unbounded Cauchy difference. After that stability problems of various functional equations have been extensively studied and generalized by a number of authors (see [4–7]). Among them, Towanlong and Nakmahachalasint [8] introduced the following functional equation with n-independent variables 2f n i=1 x i + 1≤i,j≤n i=j f(x i − x j ) = (n + 1) n i=1 f(x i ) + (n − 1) n i=1 f(−x i ),(1.1) where n is a positive integer with n ≥ 2. For real vector spaces X and Y , they proved that a function f : X → Y satisfies (1.1) if and only if there exist a quadratic ... erythropoietin D Critical Thinking Questions Describe the neural factors involved in increasing ventilation during exercise There are three neural factors that play a role in the increased ventilation... exertion without developing AMS Chapter Review Normally, the respiratory centers of the brain maintain a consistent, rhythmic breathing cycle However, in certain cases, the respiratory system must... hemoglobin molecule, there will be more hemoglobin present, and 3/5 Modifications in Respiratory Functions therefore more oxygen in the blood Over time, this allows the person to partake in physical