<b>Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Tidal expiratory flow limitation (tEFL) is defined as absence of increase...<b>Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Tidal expiratory flow limitation (tEFL) is defined as absence of increase in air flow during forced expiration compared to tidal breathing and is related to dyspnea at rest and minimal exertion in patients with chronic airflow limitation (CAL). Tidal EFL has not been expressed as a continuous variable (0% - 100%) in previous analyses. </span><b><span style="font-family:Verdana;">Objective:</span></b><span style="font-family:Verdana;"> To relate the magnitude of tEFL to spirometric values and Modified Medical Research Council (MMRC) score and Asthma Control Test (ACT). </span><b><span style="font-family:Verdana;">Methods:</span></b><span style="font-family:Verdana;"> Tidal EFL was computed as percent of the tidal volume (0% - 100%) spanned (intersected) by the forced expiratory-volume curve. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">Of 353 patients screened, 192 (114 M, 78 F) patients (136 with COPD, 56 with asthma) had CAL. Overall characteristics: (mean ± SD) age 59 ± 11 years, BMI 28 ± 7, FVC (% pred) 85 ± 20, FEV1 (% pred) 66 ± 21, FEV1/FVC 55% ± 10%, RV (% pred) 147 ± 42. Tidal EFL in patients with tEFL was 53% ± 39%. Using univariate analysis, strongest correlations were between tEFL and FVC and between tEFL and RV in patients with BMI < 30 kg/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">. In patients with nonreversible CAL, tEFL was positively associated with increasing MMRC, negatively with spirometric measurements, and positively with RV/TLC. In asthmatics, ACT scores were higher in patients with mean BMI ≥ 28 kg/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> (p < 0.00014) and RV/TLC values > 40% (p < 0.03). </span><b><span style="font-family:Verdana;">Conclusions:</span></b><span style="font-family:Verdana;"> Dyspnea is strongly associated with tEFL and lung function, particularly in patients with nonreversible CAL. Air trapping and </span><span style="font-family:Verdana;">BMI contribute to tEFL.展开更多
Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The l...Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications.展开更多
On the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle （SPP） and grain boundary （GB） as viewed f...On the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle （SPP） and grain boundary （GB） as viewed from the applicability of grain boundary equation. Also, a new expression describing the interaction range has been derived, which solves the problem in theory that the interaction range between SPP and GB can only be qualitatively analyzed previously. It is shown that given the interaction position between SPP and GB, the interaction range can be quantitatively determined by use of this expression.展开更多
The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodyn...The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodynamics.Threedimensional wave equations of soil are decoupled through differential transformation and variable separation.Consequently,expressions of soil displacements and horizontal resistances can be obtained.An analytical solution of the pile is derived based on continuity conditions between the pile and soil,subsequently from which expressions of the complex impedances are deduced.Analyses are carried out to examine the second-order effect of axial force on the horizontal vibrating behavior of the pipe pile.Some conclusions can be summarized as follows： stiffness and damping factors are decreased with the application of axial force on the pile head; distributions of the pile horizontal displacement and rotation angle are regenerated due to the second-order effect of the applied axial force; and redistributions of the bending moment and shearing force occur due to the second-order effect of the applied axial force.展开更多
A complete semi-analytical solution is obtained for second-order diffraction of plane bichromatic waves by a fixed truncated circular column.The fluid domain is divided into interior and exterior regions.In the exteri...A complete semi-analytical solution is obtained for second-order diffraction of plane bichromatic waves by a fixed truncated circular column.The fluid domain is divided into interior and exterior regions.In the exterior region,the second-order velocity potential is expressed in terms of‘locked-wave’and‘free-wave’ components,both are solved using Fourier and eigenfunction expansions.The re- sulting‘locked wave’potential is expressed by one-dimensional Green's integrals with oscillating integrands.In order to increase computational efficiency,the far-field part of the integrals are carried out analytically.Solutions in both regions are matched on the interface by the potential and its normal derivative continuity conditions.Based on the present approach,the sum-and difference-frequency potentials are efficiently evaluated and are used to generate the quadratic transfer functions which correlates the incident wave spectrum with second-order forcing spectrum on the column.The sum-frequency QTFs for a TLP column are present,which are compared for some frequency pairs with those from a fully numerical procedure.Satisfactory agreement has been obtained.QTF spectra for a case study TLP column,generated using the semi-analytical solution are presented.Also given are the results for nonlinear wave field around the column.展开更多
This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave fo...This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave force is calculated using the full-field quadratic transfer function(QTF). The coupled effect of the horizontal motions, such as surge, sway and yaw motions, and the set-down motion are taken into consideration by the nonlinear restoring matrix. The time-domain analysis with 50-yr random sea state is performed. A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform. The analysis shows that the second-order wave force has a major impact on motions of the TLP. The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway, and also will induce a large set-down motion which is an important part of heave motion. Besides, the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch. However, little influence of second-order wave force is found on the yaw motion.展开更多
Based on the entropy generation concept of thermodynamics, this paper estabfished a general theoretical model for the analysis of entropy generation to optimize fins, in which the minimum entropy generation was select...Based on the entropy generation concept of thermodynamics, this paper estabfished a general theoretical model for the analysis of entropy generation to optimize fins, in which the minimum entropy generation was selected as the object to be studied. The irreversibility due to heat transfer and friction was taken into account so that the minimum entropy generation number has been analyzed with respect to second law of thermodynamics in the forced cross-flow. The optimum dimensions of cylinder pins were discussed. It＇s found that the minimum entropy generation number depends on parameters related to the fluid and fin physical parameters. Varlatioms of the minimum entropy generation number with different parameters were analyzed.展开更多
-In this paper, an analytical solution in the outer region of finite water depth is derived for the second-order diffraction potential, which gives a clear physical meaning of the wave transmission and reflection char...-In this paper, an analytical solution in the outer region of finite water depth is derived for the second-order diffraction potential, which gives a clear physical meaning of the wave transmission and reflection characteristics in the far field. A numerical method-simple Green's function technique-for calculating the second-order diffraction potential in the inner region is also described. Numerical results are provided for the second-order wave forces on a semi-submerged cylinder. It is found that the contribution of second-order diffraction potential to second-order wave forces is important. The effect of water depth and submerged depth on the wave force is also discussed.展开更多
So far many investigations have been made on nonlinear wave diffraction problemfor a large-diameter vertical circular cylinder. However,there are still some problemsworthy to be further discussed. It includes that the...So far many investigations have been made on nonlinear wave diffraction problemfor a large-diameter vertical circular cylinder. However,there are still some problemsworthy to be further discussed. It includes that the second order radiation condition isnot very clear and the inhomogeneous term of second order free surface boundarycondition makes the calculation of second order wave force either not easier to beperformed accurately due to its slowly decaying with radial distance or toocomplicated for practical application. In this paper, the second order radiationcondition is posed of the circumferential Fourier components of second orderpotential, instead of the second order potential. It is found that the circumferenatialFourier cormponents of second order potential have to satisfy Sommerfeld radiationcondition. By means of the mathematical formulae derived in this paper, theinhomogeneous term of second order free surface boundary condition were simplifiedand then an exact expression of second order wave force was obtained, which issimpler in form and easier to be used in practical calculation. The calculation resultsagree well with some experimental data.展开更多
Background Obesity is the most common metabolic disease in the world. However, the relationship between obesity and lung function is not fully understood. Although several longitudinal studies have shown that increase...Background Obesity is the most common metabolic disease in the world. However, the relationship between obesity and lung function is not fully understood. Although several longitudinal studies have shown that increases in body weight can lead to reductions in pulmonary function, whether this is the case with the Japanese population and whether high body mass index （BMI） status alone represents an appropriate predictor of obstructive lung dysfunction remains unclear.The purpose of present study was to estimate the effect of BMI on lung function measured by spirometry of Japanese patients in general clinics. We measured BMI and performed spirometry on screening patients who had consulted general clinics.Methods Subjects comprised 1231 patients ≥40 years of age （mean age （65.0±12.0） years, 525 men, 706 women） who had consulted clinics in Nagasaki Prefecture, Japan, for non-respiratory disease. BMI was calculated and lung function was measured by spirometry.Results BMI was found to be positively correlated with forced expiratory volume in 1 second （FEV1）/forced vital capacity （FVC） in men and with maximum mid-expiratory flow （MMF） in all subjects. Following adjustment for relevant factors, a significant positive correlation between BMI and FEV1/FVC was identified for all subjects. Comparison between subjects with normal BMI （18.5-25.0） and higher BMI （25.1-30.0） also demonstrated that FEV1/FVC and percentage of predicted maximum mid-expiratory flow （%MMF） were significantly higher in the latter subjects.Conclusions In a population without marked respiratory disease, higher BMI subjects showed less obstructive pulmonary dysfunction compared to normal BMI subjects. High BMI status alone may be inappropriate as a predictor of obstructive lung dysfunction, particularly in populations with a low prevalence of obesity.展开更多
BACKGROUND Chronic obstructive pulmonary disease(COPD)is a progressive respiratory condition often associated with a high incidence of osteoporosis.Studies indicate that patients with COPD present with a significant d...BACKGROUND Chronic obstructive pulmonary disease(COPD)is a progressive respiratory condition often associated with a high incidence of osteoporosis.Studies indicate that patients with COPD present with a significant decrease in bone mineral density(BMD),potentially related to inflammation and corticosteroid use.AIM To investigate the relationship between BMD and lung function,mainly the forced expiratory volume in the forced expiratory volume in 1 second(FEV1)/forced vital capacity percentage(FVC%),in patients with COPD using quantitative computed tomography(QCT).METHODS This prospective cross-sectional study included 85 patients with COPD treated at Gansu Provincial People's Hospital.Exposure variables included lung function parameter(FEV1/FVC%),age,sex,body mass index,smoking status,tea-drinking habits,and physical activity.BMD was measured using QCT.Linear regression and generalized additive models were employed to analyze the relationship between exposure variables and BMD.RESULTS Linear regression analysis revealed a significant positive relationship between BMD and FEV1/FVC%(β=0.1,95%confidence interval[CI]:0.1-0.1;P<0.0001).Non-linear analysis identified a unique BMD breakpoint of 128.08 mg/cm³.Before the breakpoint,BMD was significantly positively correlated with FEV1/FVC%(β=0.245;P=0.0019);while after the breakpoint,the relationship was negative and showed no statistical significance(β=-0.136;P=0.0753).This finding underscores the critical role of BMD in COPD management and highlights the importance of individualized clinical interventions in improvement of lung function and overall health status in patients.CONCLUSION There is a complex non-linear relationship between BMD and lung function in patients with COPD,highlighting the importance of monitoring change in bone density during the management of COPD.展开更多
文摘<b>Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Tidal expiratory flow limitation (tEFL) is defined as absence of increase in air flow during forced expiration compared to tidal breathing and is related to dyspnea at rest and minimal exertion in patients with chronic airflow limitation (CAL). Tidal EFL has not been expressed as a continuous variable (0% - 100%) in previous analyses. </span><b><span style="font-family:Verdana;">Objective:</span></b><span style="font-family:Verdana;"> To relate the magnitude of tEFL to spirometric values and Modified Medical Research Council (MMRC) score and Asthma Control Test (ACT). </span><b><span style="font-family:Verdana;">Methods:</span></b><span style="font-family:Verdana;"> Tidal EFL was computed as percent of the tidal volume (0% - 100%) spanned (intersected) by the forced expiratory-volume curve. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">Of 353 patients screened, 192 (114 M, 78 F) patients (136 with COPD, 56 with asthma) had CAL. Overall characteristics: (mean ± SD) age 59 ± 11 years, BMI 28 ± 7, FVC (% pred) 85 ± 20, FEV1 (% pred) 66 ± 21, FEV1/FVC 55% ± 10%, RV (% pred) 147 ± 42. Tidal EFL in patients with tEFL was 53% ± 39%. Using univariate analysis, strongest correlations were between tEFL and FVC and between tEFL and RV in patients with BMI < 30 kg/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">. In patients with nonreversible CAL, tEFL was positively associated with increasing MMRC, negatively with spirometric measurements, and positively with RV/TLC. In asthmatics, ACT scores were higher in patients with mean BMI ≥ 28 kg/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> (p < 0.00014) and RV/TLC values > 40% (p < 0.03). </span><b><span style="font-family:Verdana;">Conclusions:</span></b><span style="font-family:Verdana;"> Dyspnea is strongly associated with tEFL and lung function, particularly in patients with nonreversible CAL. Air trapping and </span><span style="font-family:Verdana;">BMI contribute to tEFL.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11934009,11974187,and 11604156)。
文摘Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications.
基金the financial support from the Supporting Plan for New Century Excellent Talents,MOE,China under grant No.NCET-04-0257the National Natural Science Foundation of China(No.50471070)the Natural Science Foundation of Shanxi Province(No.20051050).
文摘On the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle （SPP） and grain boundary （GB） as viewed from the applicability of grain boundary equation. Also, a new expression describing the interaction range has been derived, which solves the problem in theory that the interaction range between SPP and GB can only be qualitatively analyzed previously. It is shown that given the interaction position between SPP and GB, the interaction range can be quantitatively determined by use of this expression.
基金National Natural Science Foundation of China under Grant Nos.51622803 and 51708064the National Key Research and Development Program of China under Grant No.2016YFE0200100
文摘The second-order effect of axial force on horizontal vibrating characteristics of a large-diameter pipe pile is theoretically investigated.Governing equations of the pile-soil system are established based on elastodynamics.Threedimensional wave equations of soil are decoupled through differential transformation and variable separation.Consequently,expressions of soil displacements and horizontal resistances can be obtained.An analytical solution of the pile is derived based on continuity conditions between the pile and soil,subsequently from which expressions of the complex impedances are deduced.Analyses are carried out to examine the second-order effect of axial force on the horizontal vibrating behavior of the pipe pile.Some conclusions can be summarized as follows： stiffness and damping factors are decreased with the application of axial force on the pile head; distributions of the pile horizontal displacement and rotation angle are regenerated due to the second-order effect of the applied axial force; and redistributions of the bending moment and shearing force occur due to the second-order effect of the applied axial force.
文摘A complete semi-analytical solution is obtained for second-order diffraction of plane bichromatic waves by a fixed truncated circular column.The fluid domain is divided into interior and exterior regions.In the exterior region,the second-order velocity potential is expressed in terms of‘locked-wave’and‘free-wave’ components,both are solved using Fourier and eigenfunction expansions.The re- sulting‘locked wave’potential is expressed by one-dimensional Green's integrals with oscillating integrands.In order to increase computational efficiency,the far-field part of the integrals are carried out analytically.Solutions in both regions are matched on the interface by the potential and its normal derivative continuity conditions.Based on the present approach,the sum-and difference-frequency potentials are efficiently evaluated and are used to generate the quadratic transfer functions which correlates the incident wave spectrum with second-order forcing spectrum on the column.The sum-frequency QTFs for a TLP column are present,which are compared for some frequency pairs with those from a fully numerical procedure.Satisfactory agreement has been obtained.QTF spectra for a case study TLP column,generated using the semi-analytical solution are presented.Also given are the results for nonlinear wave field around the column.
基金supported by the National Natural Science Foundation of China(Nos.51239008 and 51279130)
文摘This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave force is calculated using the full-field quadratic transfer function(QTF). The coupled effect of the horizontal motions, such as surge, sway and yaw motions, and the set-down motion are taken into consideration by the nonlinear restoring matrix. The time-domain analysis with 50-yr random sea state is performed. A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform. The analysis shows that the second-order wave force has a major impact on motions of the TLP. The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway, and also will induce a large set-down motion which is an important part of heave motion. Besides, the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch. However, little influence of second-order wave force is found on the yaw motion.
文摘Based on the entropy generation concept of thermodynamics, this paper estabfished a general theoretical model for the analysis of entropy generation to optimize fins, in which the minimum entropy generation was selected as the object to be studied. The irreversibility due to heat transfer and friction was taken into account so that the minimum entropy generation number has been analyzed with respect to second law of thermodynamics in the forced cross-flow. The optimum dimensions of cylinder pins were discussed. It＇s found that the minimum entropy generation number depends on parameters related to the fluid and fin physical parameters. Varlatioms of the minimum entropy generation number with different parameters were analyzed.
文摘-In this paper, an analytical solution in the outer region of finite water depth is derived for the second-order diffraction potential, which gives a clear physical meaning of the wave transmission and reflection characteristics in the far field. A numerical method-simple Green's function technique-for calculating the second-order diffraction potential in the inner region is also described. Numerical results are provided for the second-order wave forces on a semi-submerged cylinder. It is found that the contribution of second-order diffraction potential to second-order wave forces is important. The effect of water depth and submerged depth on the wave force is also discussed.
文摘So far many investigations have been made on nonlinear wave diffraction problemfor a large-diameter vertical circular cylinder. However,there are still some problemsworthy to be further discussed. It includes that the second order radiation condition isnot very clear and the inhomogeneous term of second order free surface boundarycondition makes the calculation of second order wave force either not easier to beperformed accurately due to its slowly decaying with radial distance or toocomplicated for practical application. In this paper, the second order radiationcondition is posed of the circumferential Fourier components of second orderpotential, instead of the second order potential. It is found that the circumferenatialFourier cormponents of second order potential have to satisfy Sommerfeld radiationcondition. By means of the mathematical formulae derived in this paper, theinhomogeneous term of second order free surface boundary condition were simplifiedand then an exact expression of second order wave force was obtained, which issimpler in form and easier to be used in practical calculation. The calculation resultsagree well with some experimental data.
文摘Background Obesity is the most common metabolic disease in the world. However, the relationship between obesity and lung function is not fully understood. Although several longitudinal studies have shown that increases in body weight can lead to reductions in pulmonary function, whether this is the case with the Japanese population and whether high body mass index （BMI） status alone represents an appropriate predictor of obstructive lung dysfunction remains unclear.The purpose of present study was to estimate the effect of BMI on lung function measured by spirometry of Japanese patients in general clinics. We measured BMI and performed spirometry on screening patients who had consulted general clinics.Methods Subjects comprised 1231 patients ≥40 years of age （mean age （65.0±12.0） years, 525 men, 706 women） who had consulted clinics in Nagasaki Prefecture, Japan, for non-respiratory disease. BMI was calculated and lung function was measured by spirometry.Results BMI was found to be positively correlated with forced expiratory volume in 1 second （FEV1）/forced vital capacity （FVC） in men and with maximum mid-expiratory flow （MMF） in all subjects. Following adjustment for relevant factors, a significant positive correlation between BMI and FEV1/FVC was identified for all subjects. Comparison between subjects with normal BMI （18.5-25.0） and higher BMI （25.1-30.0） also demonstrated that FEV1/FVC and percentage of predicted maximum mid-expiratory flow （%MMF） were significantly higher in the latter subjects.Conclusions In a population without marked respiratory disease, higher BMI subjects showed less obstructive pulmonary dysfunction compared to normal BMI subjects. High BMI status alone may be inappropriate as a predictor of obstructive lung dysfunction, particularly in populations with a low prevalence of obesity.
基金Supported by National Natural Science Foundation of China(NSFC)of China,No.82360358Internal Medicine Research Project of Gansu Provincial People's Hospital,No.22GSSYD-77Natural Science Foundation of Gansu Province,No.22JR5RA659.
文摘BACKGROUND Chronic obstructive pulmonary disease(COPD)is a progressive respiratory condition often associated with a high incidence of osteoporosis.Studies indicate that patients with COPD present with a significant decrease in bone mineral density(BMD),potentially related to inflammation and corticosteroid use.AIM To investigate the relationship between BMD and lung function,mainly the forced expiratory volume in the forced expiratory volume in 1 second(FEV1)/forced vital capacity percentage(FVC%),in patients with COPD using quantitative computed tomography(QCT).METHODS This prospective cross-sectional study included 85 patients with COPD treated at Gansu Provincial People's Hospital.Exposure variables included lung function parameter(FEV1/FVC%),age,sex,body mass index,smoking status,tea-drinking habits,and physical activity.BMD was measured using QCT.Linear regression and generalized additive models were employed to analyze the relationship between exposure variables and BMD.RESULTS Linear regression analysis revealed a significant positive relationship between BMD and FEV1/FVC%(β=0.1,95%confidence interval[CI]:0.1-0.1;P<0.0001).Non-linear analysis identified a unique BMD breakpoint of 128.08 mg/cm³.Before the breakpoint,BMD was significantly positively correlated with FEV1/FVC%(β=0.245;P=0.0019);while after the breakpoint,the relationship was negative and showed no statistical significance(β=-0.136;P=0.0753).This finding underscores the critical role of BMD in COPD management and highlights the importance of individualized clinical interventions in improvement of lung function and overall health status in patients.CONCLUSION There is a complex non-linear relationship between BMD and lung function in patients with COPD,highlighting the importance of monitoring change in bone density during the management of COPD.
