The benchmark for assessing quality of long-term glycemic control and adjustment of therapy is currently glycated hemoglobin(Hb A1c). Despite its importance as an indicator for the development of diabeticcomplications...The benchmark for assessing quality of long-term glycemic control and adjustment of therapy is currently glycated hemoglobin(Hb A1c). Despite its importance as an indicator for the development of diabeticcomplications, recent studies have revealed that this metric has some limitations; it conveys a rather complex message, which has to be taken into consideration for diabetes screening and treatment. On the basis of recent clinical trials, the relationship between Hb A1 c and cardiovascular outcomes in long-standing diabetes has been called into question. It becomes obvious that other surrogate and biomarkers are needed to better predict cardiovascular diabetes complications and assess efficiency of therapy. Glycated albumin, fructosamin, and 1,5-anhydroglucitol have received growing interest as alternative markers of glycemic control. In addition to measures of hyperglycemia, advanced glucose monitoring methods became available. An indispensible adjunct to Hb A1 c in routine diabetes care is selfmonitoring of blood glucose. This monitoring method is now widely used, as it provides immediate feedback to patients on short-term changes, involving fasting, preprandial, and postprandial glucose levels. Beyond the traditional metrics, glycemic variability has been identified as a predictor of hypoglycemia, and it might also be implicated in the pathogenesis of vascular diabetes complications. Assessment of glycemic variability is thus important, but exact quantification requires frequently sampled glucose measurements. In order to optimize diabetes treatment, there is a need for both key metrics of glycemic control on a day-to-day basis and for more advanced, user-friendly monitoring methods. In addition to traditional discontinuous glucose testing, continuous glucose sensing has become a useful tool to reveal insufficient glycemic management. This new technology is particularly effective in patients with complicated diabetes and provides the opportunity to characterize glucose dynamics. Several continuous glucose moni展开更多
We study the dynamical properties of heart rate variability （HRV） in sleep by analysing the scaling behaviour with the multifractal detrended fluctuation analysis method. It is well known that heart rate is regulate...We study the dynamical properties of heart rate variability （HRV） in sleep by analysing the scaling behaviour with the multifractal detrended fluctuation analysis method. It is well known that heart rate is regulated by the interaction of two branches of the autonomic nervous system： the parasympathetic and sympathetic nervous systems. By investigating the multifractal properties of light, deep, rapid-eye-movement （REM） sleep and wake stages, we firstly find an increasing multifractal behaviour during REM sleep which may be caused by augmented sympathetic activities relative to non-REM sleep. In addition, the investigation of long-range correlations of HRV in sleep with second order detrended fluctuation analysis presents irregular phenomena. These findings may be helpful to understand the underlying regulating mechanism of heart rate by autonomic nervous system during wake-sleep transitions.展开更多
Traditional biomechanical analyses of human movement are generally derived from linear mathematics.While these methods can be useful in many situations,they do not describe behaviors in human systems that are predomin...Traditional biomechanical analyses of human movement are generally derived from linear mathematics.While these methods can be useful in many situations,they do not describe behaviors in human systems that are predominately nonlinear.For this reason,nonlinear analysis methods based on a dynamical systems approach have become more prevalent in recent literature.These analysis techniques have provided new insights into how systems(1) maintain pattern stability,(2) transition into new states,and(3) are governed by short-and long-term(fractal) correlational processes at different spatio-temporal scales.These different aspects of system dynamics are typically investigated using concepts related to variability,stability,complexity,and adaptability.The purpose of this paper is to compare and contrast these different concepts and demonstrate that,although related,these terms represent fundamentally different aspects of system dynamics.In particular,we argue that variability should not uniformly be equated with stability or complexity of movement.In addition,current dynamic stability measures based on nonlinear analysis methods(such as the finite maximal Lyapunov exponent) can reveal local instabilities in movement dynamics,but the degree to which these local instabilities relate to global postural and gait stability and the ability to resist external perturbations remains to be explored.Finally,systematic studies are needed to relate observed reductions in complexity with aging and disease to the adaptive capabilities of the movement system and how complexity changes as a function of different task constraints.展开更多
In this article,we address both recent advances and open questions in some mathematical and computational issues in geophysical fluid dynamics(GFD)and climate dynamics.The main focus is on 1)the primitive equations(PE...In this article,we address both recent advances and open questions in some mathematical and computational issues in geophysical fluid dynamics(GFD)and climate dynamics.The main focus is on 1)the primitive equations(PEs)models and their related mathematical and computational issues,2)climate variability,predictability and successive bifurcation,and 3)a new dynamical systems theory and its applications to GFD and climate dynamics.展开更多
Within savanna environments, movements of elephant are influenced by changes in climate especially seasonal rainfall. In this study, we investigated the possible changes in elephant population based on projected rainf...Within savanna environments, movements of elephant are influenced by changes in climate especially seasonal rainfall. In this study, we investigated the possible changes in elephant population based on projected rainfall changes using regional climate models (RCM) and Representative Concentration Pathways (RCPs). The relationship between elephant and rainfall was modelled against annual, wet season, dry season rainfall based on various time lags. Future relation between elephant and rainfall was projected based on three RCPs;2.6, 4.5 and 8.5. There was a strong linear relationship between elephant and October-November-December (OND) rains with time lag of 13 years (Y = −4016.43 + 19.11x, r2 = 0.459, P = 0.006). The rainfall trends for RCP 2.6 and 4.5 showed a slight increase in annual rainfall for the period 2006-2100 but driven by OND increases. Rainfall increase for RCP 8.5 was significant and was driven by increase in both March-April-May (MAM) and OND. These rainfall dynamics had influence on the projected elephant population in the Amboseli ecosystem. For RCP 2.6 and 4.5 the elephant population increase was 2455 and 2814 respectively. RCP 8.5 elephant population doubled to an average of 3348 elephants. In all the RCPs there are seasonal and yearly variations and absolute number varies from the average. The range of variation is small in RCPs 2.6 and 4.5 compared to RCP 8.5. Evidently, elephant population will increase based on projected rainfall projections surpassing park capacity. It therefore, requires that the Park authority put in place measures that could contain these numbers including opening of blocked wildlife corridors, maintain the cross border movement of Amboseli elephant with Tanzania in that case ensure there is no poaching. Lastly, work with local communities so that they can benefit from tourism through setting up conservancies through which they could minimize the human elephant conflicts based on the projected elephant population.展开更多
Background: In the contxt of ecosystem management, the present study aims to compare the natural and the present-day forested landscapes of a large territory in Quebec(Canada). Using contemporary and long-term fire cy...Background: In the contxt of ecosystem management, the present study aims to compare the natural and the present-day forested landscapes of a large territory in Quebec(Canada). Using contemporary and long-term fire cycles, each natural forst landscape is defined according to the variability of its structure and composition, and compared to the present-day landscape. This analysis was conducted to address the question of whether human activities have moved these ecosystems outside the range of natural landscape variability.Methods: The study encompassed a forested area of 175 000 km2 divided into 14 landscapes. Using a framework that integrates fire cycles, age structure and forest dynamics, we characterized the forest composition and age structures that resulted from three historical fire cycles(110,140, and 180 years) representative of the boreal forest of eastern Canada. The modeled natural landscapes were compared with present-day landscapes in regard to the proportion of old-growth forests(landscape level) and the proportion of late-successional forest stands(landscape level and potential vegetation type).Results: Four landscapes(39%) remain within their natural range of variability. In contrast, nine landscapes(54%)show a large gap between natural and present-day landscapes. These nine are located in the southern portion of the study area, and are mainly associated with Abies-Betula vegetation where human activities have contributed to a strong increase in the proportion of Populus tremuloides stands(early-successional stages) and a decrease of oldgrowth forest stands(more than 100 years old). A single landscape(7%), substantially changed from its potential natural state, is a candidate for adaptive-based management.Conclusion: Comparison of corresponding natural(reference conditions) and present-day landscapes showed that ten landscapes reflecting an important shift in forest composition and age structure could be considered beyond the range of their natural variability. The description of a landscape's nat展开更多
Soil temperature is a key factor for best planting dates decision-making in the large scale farming areas of northeast China because of high latitudes and frigid environment.Continuous data were collected from a wirel...Soil temperature is a key factor for best planting dates decision-making in the large scale farming areas of northeast China because of high latitudes and frigid environment.Continuous data were collected from a wireless sensor network(WSN)-based monitoring system to exactly analyze and understand soil temperature of the whole farmland.Using the classical statistics and geo-statistics methods,real-time monitoring data were analyzed with three aspects,i.e.temporal variation,spatial variation and spatio-temporal variation.Temporal variation analysis of each sensor node showed a sinusoidal curve of daily soil temperature and gave the long-term trend of daily average soil temperature in a certain period.Spatial variation analysis provided the spatial distribution map of daily average soil temperature within a study region for a certain day.Spatio-temporal variation analysis quantified the variation process of the spatial distribution over time by the monitored classes distribution indicator(MCDI)proposed.Experimental results showed that the above variations analysis of the real-time data provide an effective approach to determine whole-farmland soil temperature.展开更多
It is difficult to establish the process of chaos in time series from cardiac dynamics. The output from such a system is probably the result of both its internal dynamics, and the input to the system from its surround...It is difficult to establish the process of chaos in time series from cardiac dynamics. The output from such a system is probably the result of both its internal dynamics, and the input to the system from its surroundings. We present an optimization algorithm to find a time series that is as close as possible to the heart rate series subject to the constraint that it is deterministic with respect to some dynamics. The algorithm is tested by some famous forced dynamical systems, and applied to heart rate data. We find that the deterministic components of heart rate variability are chaotic.展开更多
文摘The benchmark for assessing quality of long-term glycemic control and adjustment of therapy is currently glycated hemoglobin(Hb A1c). Despite its importance as an indicator for the development of diabeticcomplications, recent studies have revealed that this metric has some limitations; it conveys a rather complex message, which has to be taken into consideration for diabetes screening and treatment. On the basis of recent clinical trials, the relationship between Hb A1 c and cardiovascular outcomes in long-standing diabetes has been called into question. It becomes obvious that other surrogate and biomarkers are needed to better predict cardiovascular diabetes complications and assess efficiency of therapy. Glycated albumin, fructosamin, and 1,5-anhydroglucitol have received growing interest as alternative markers of glycemic control. In addition to measures of hyperglycemia, advanced glucose monitoring methods became available. An indispensible adjunct to Hb A1 c in routine diabetes care is selfmonitoring of blood glucose. This monitoring method is now widely used, as it provides immediate feedback to patients on short-term changes, involving fasting, preprandial, and postprandial glucose levels. Beyond the traditional metrics, glycemic variability has been identified as a predictor of hypoglycemia, and it might also be implicated in the pathogenesis of vascular diabetes complications. Assessment of glycemic variability is thus important, but exact quantification requires frequently sampled glucose measurements. In order to optimize diabetes treatment, there is a need for both key metrics of glycemic control on a day-to-day basis and for more advanced, user-friendly monitoring methods. In addition to traditional discontinuous glucose testing, continuous glucose sensing has become a useful tool to reveal insufficient glycemic management. This new technology is particularly effective in patients with complicated diabetes and provides the opportunity to characterize glucose dynamics. Several continuous glucose moni
基金Supported by the National Science Foundation of China under Grant Nos 60471057 and 70571075, and the Foundation for Graduate Student of USTC under Grant No KD2006046.
文摘We study the dynamical properties of heart rate variability （HRV） in sleep by analysing the scaling behaviour with the multifractal detrended fluctuation analysis method. It is well known that heart rate is regulated by the interaction of two branches of the autonomic nervous system： the parasympathetic and sympathetic nervous systems. By investigating the multifractal properties of light, deep, rapid-eye-movement （REM） sleep and wake stages, we firstly find an increasing multifractal behaviour during REM sleep which may be caused by augmented sympathetic activities relative to non-REM sleep. In addition, the investigation of long-range correlations of HRV in sleep with second order detrended fluctuation analysis presents irregular phenomena. These findings may be helpful to understand the underlying regulating mechanism of heart rate by autonomic nervous system during wake-sleep transitions.
文摘Traditional biomechanical analyses of human movement are generally derived from linear mathematics.While these methods can be useful in many situations,they do not describe behaviors in human systems that are predominately nonlinear.For this reason,nonlinear analysis methods based on a dynamical systems approach have become more prevalent in recent literature.These analysis techniques have provided new insights into how systems(1) maintain pattern stability,(2) transition into new states,and(3) are governed by short-and long-term(fractal) correlational processes at different spatio-temporal scales.These different aspects of system dynamics are typically investigated using concepts related to variability,stability,complexity,and adaptability.The purpose of this paper is to compare and contrast these different concepts and demonstrate that,although related,these terms represent fundamentally different aspects of system dynamics.In particular,we argue that variability should not uniformly be equated with stability or complexity of movement.In addition,current dynamic stability measures based on nonlinear analysis methods(such as the finite maximal Lyapunov exponent) can reveal local instabilities in movement dynamics,but the degree to which these local instabilities relate to global postural and gait stability and the ability to resist external perturbations remains to be explored.Finally,systematic studies are needed to relate observed reductions in complexity with aging and disease to the adaptive capabilities of the movement system and how complexity changes as a function of different task constraints.
基金the grants from the Office of Naval Research,from the National Science Foundation,and from the National Nature Science Foundation of China(40325013,40675046)。
文摘In this article,we address both recent advances and open questions in some mathematical and computational issues in geophysical fluid dynamics(GFD)and climate dynamics.The main focus is on 1)the primitive equations(PEs)models and their related mathematical and computational issues,2)climate variability,predictability and successive bifurcation,and 3)a new dynamical systems theory and its applications to GFD and climate dynamics.
文摘Within savanna environments, movements of elephant are influenced by changes in climate especially seasonal rainfall. In this study, we investigated the possible changes in elephant population based on projected rainfall changes using regional climate models (RCM) and Representative Concentration Pathways (RCPs). The relationship between elephant and rainfall was modelled against annual, wet season, dry season rainfall based on various time lags. Future relation between elephant and rainfall was projected based on three RCPs;2.6, 4.5 and 8.5. There was a strong linear relationship between elephant and October-November-December (OND) rains with time lag of 13 years (Y = −4016.43 + 19.11x, r2 = 0.459, P = 0.006). The rainfall trends for RCP 2.6 and 4.5 showed a slight increase in annual rainfall for the period 2006-2100 but driven by OND increases. Rainfall increase for RCP 8.5 was significant and was driven by increase in both March-April-May (MAM) and OND. These rainfall dynamics had influence on the projected elephant population in the Amboseli ecosystem. For RCP 2.6 and 4.5 the elephant population increase was 2455 and 2814 respectively. RCP 8.5 elephant population doubled to an average of 3348 elephants. In all the RCPs there are seasonal and yearly variations and absolute number varies from the average. The range of variation is small in RCPs 2.6 and 4.5 compared to RCP 8.5. Evidently, elephant population will increase based on projected rainfall projections surpassing park capacity. It therefore, requires that the Park authority put in place measures that could contain these numbers including opening of blocked wildlife corridors, maintain the cross border movement of Amboseli elephant with Tanzania in that case ensure there is no poaching. Lastly, work with local communities so that they can benefit from tourism through setting up conservancies through which they could minimize the human elephant conflicts based on the projected elephant population.
基金funded by the Ministère des Forêts,de la Faune et des Parcs du Québec(MFFP).The funds were used mainly for the salary of the authors working for the MFFP
文摘Background: In the contxt of ecosystem management, the present study aims to compare the natural and the present-day forested landscapes of a large territory in Quebec(Canada). Using contemporary and long-term fire cycles, each natural forst landscape is defined according to the variability of its structure and composition, and compared to the present-day landscape. This analysis was conducted to address the question of whether human activities have moved these ecosystems outside the range of natural landscape variability.Methods: The study encompassed a forested area of 175 000 km2 divided into 14 landscapes. Using a framework that integrates fire cycles, age structure and forest dynamics, we characterized the forest composition and age structures that resulted from three historical fire cycles(110,140, and 180 years) representative of the boreal forest of eastern Canada. The modeled natural landscapes were compared with present-day landscapes in regard to the proportion of old-growth forests(landscape level) and the proportion of late-successional forest stands(landscape level and potential vegetation type).Results: Four landscapes(39%) remain within their natural range of variability. In contrast, nine landscapes(54%)show a large gap between natural and present-day landscapes. These nine are located in the southern portion of the study area, and are mainly associated with Abies-Betula vegetation where human activities have contributed to a strong increase in the proportion of Populus tremuloides stands(early-successional stages) and a decrease of oldgrowth forest stands(more than 100 years old). A single landscape(7%), substantially changed from its potential natural state, is a candidate for adaptive-based management.Conclusion: Comparison of corresponding natural(reference conditions) and present-day landscapes showed that ten landscapes reflecting an important shift in forest composition and age structure could be considered beyond the range of their natural variability. The description of a landscape's nat
基金National Nature Science Foundation of China(Grant No.31101078,31571563,31571564)National High Technology Research and Development Program of China(Grant No.2013AA102308)Scientific Research Common Program of Beijing Municipal Commission of Education(Grant No.KM201410028016).
文摘Soil temperature is a key factor for best planting dates decision-making in the large scale farming areas of northeast China because of high latitudes and frigid environment.Continuous data were collected from a wireless sensor network(WSN)-based monitoring system to exactly analyze and understand soil temperature of the whole farmland.Using the classical statistics and geo-statistics methods,real-time monitoring data were analyzed with three aspects,i.e.temporal variation,spatial variation and spatio-temporal variation.Temporal variation analysis of each sensor node showed a sinusoidal curve of daily soil temperature and gave the long-term trend of daily average soil temperature in a certain period.Spatial variation analysis provided the spatial distribution map of daily average soil temperature within a study region for a certain day.Spatio-temporal variation analysis quantified the variation process of the spatial distribution over time by the monitored classes distribution indicator(MCDI)proposed.Experimental results showed that the above variations analysis of the real-time data provide an effective approach to determine whole-farmland soil temperature.
文摘It is difficult to establish the process of chaos in time series from cardiac dynamics. The output from such a system is probably the result of both its internal dynamics, and the input to the system from its surroundings. We present an optimization algorithm to find a time series that is as close as possible to the heart rate series subject to the constraint that it is deterministic with respect to some dynamics. The algorithm is tested by some famous forced dynamical systems, and applied to heart rate data. We find that the deterministic components of heart rate variability are chaotic.
