Planation surface, a surface that is almost flat, is a kind of low-relief landforms. Planation surface is the consequence of the denudation and planation processes under a tectonic stable condition. The quantitative e...Planation surface, a surface that is almost flat, is a kind of low-relief landforms. Planation surface is the consequence of the denudation and planation processes under a tectonic stable condition. The quantitative expression of the characteristics of planation surface plays a key role in reconstructing and describing the evolutionary process of landforms. In this study, Landform Planation Index(LPI), a new terrain derivative, was proposed to quantify the characteristics of planation surface. The LPIs were calculated based on the summit surfaces formed according to the clustering results of peaks. Ten typical areas in the Ordos Platform located in the central part of the Loess Plateau of China are chosen as the test areas for investigating their planation characteristics with the LPI. The experimental results indicate that the LPI can be effectively used to quantify the characteristics of planation surfaces. In addition, the LPI can be further used to depict the patterns of spatial differentiation in the Ordos Platform. Although the present Ordos Platform area is full of the high-density gullies, its planation characteristics is found to be well preserved. Furthermore, the characteristics of the planation surfaces can also reflect the original morphology of the Ordos Platform before the loess dusts deposition process evolved in this area. The statistical results of the LPI show that there is a gradually increasing tendency along with the increasing of slope gradient of summit surface. It indicates that the characteristics of planation surfaces vary among test areas with different landforms. These findings help to deepen the understanding of planation characteristics of the loess landform and its underlying paleotopography. Results of this study can be also served as an important theoretical reference value for revealing the evolutionary process of loess landform.展开更多
Background Echocardiography has been shown to be a valuable resource in the diagnosis of many cardiac conditions, and can be used in all age groups, from the fetus to the oldest old. In the context of an increasingly ...Background Echocardiography has been shown to be a valuable resource in the diagnosis of many cardiac conditions, and can be used in all age groups, from the fetus to the oldest old. In the context of an increasingly aging population, the impact and utility of echocar- diography in centenarians is largely unknown. This study is to determine whether echocardiography in centenarians aids in making clinical patient management decisions. Methods A retrospective review of echocardiograms from 1986 to 2014, at two affiliated tertiary centers, in individuals who were 100 years or older at the time of the examination. Patient and echocardiogram characteristics, management decisions based on echocardiography, and mortality were documented. Results 114 centenarians had echocardiograms, with ages ranging from 100 to 107 years （101 - 1.4 years）. In 82 of the centenarians evaluated （72%）, no changes in management occurred as a consequence of the echocardiogram. From all management changes directly related to the echocardiogram, 81% （n = 26） of these corresponded to medication adjustments; interventional or surgical procedures followed the echocardiogram only in 4% （n = 5） of the total number of centenarians. Echocardiogram-based changes in management were only significant in patients that were referred for congestive heart failure （P = 0.02）. After the echocardiogram was performed, 1-month and 1-year mortality were 15% and 47%, respectively. The median survival after the echocardiogram was obtained was 13 months （range 0.03 to 145 months）, with no difference if there was a change or no change in manage- ment （P = 0.21）. Conclusions Among centenarians undergoing echocardiography, despite additional diagnostic information, echocardio- grams in centenarians influence management in a minority of cases, most commonly in the form of medication changes for treatment of heart failure. A significant proportion of centenarians are deceased within a year of undergoing echocardiographic assessment. These findings may question the overall utility of echocardiography in these late survivors.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41201464,41471316)Priority Academic Program Development of Jiangsu Higher Education Institutions(No.164320H101)
文摘Planation surface, a surface that is almost flat, is a kind of low-relief landforms. Planation surface is the consequence of the denudation and planation processes under a tectonic stable condition. The quantitative expression of the characteristics of planation surface plays a key role in reconstructing and describing the evolutionary process of landforms. In this study, Landform Planation Index(LPI), a new terrain derivative, was proposed to quantify the characteristics of planation surface. The LPIs were calculated based on the summit surfaces formed according to the clustering results of peaks. Ten typical areas in the Ordos Platform located in the central part of the Loess Plateau of China are chosen as the test areas for investigating their planation characteristics with the LPI. The experimental results indicate that the LPI can be effectively used to quantify the characteristics of planation surfaces. In addition, the LPI can be further used to depict the patterns of spatial differentiation in the Ordos Platform. Although the present Ordos Platform area is full of the high-density gullies, its planation characteristics is found to be well preserved. Furthermore, the characteristics of the planation surfaces can also reflect the original morphology of the Ordos Platform before the loess dusts deposition process evolved in this area. The statistical results of the LPI show that there is a gradually increasing tendency along with the increasing of slope gradient of summit surface. It indicates that the characteristics of planation surfaces vary among test areas with different landforms. These findings help to deepen the understanding of planation characteristics of the loess landform and its underlying paleotopography. Results of this study can be also served as an important theoretical reference value for revealing the evolutionary process of loess landform.
文摘Background Echocardiography has been shown to be a valuable resource in the diagnosis of many cardiac conditions, and can be used in all age groups, from the fetus to the oldest old. In the context of an increasingly aging population, the impact and utility of echocar- diography in centenarians is largely unknown. This study is to determine whether echocardiography in centenarians aids in making clinical patient management decisions. Methods A retrospective review of echocardiograms from 1986 to 2014, at two affiliated tertiary centers, in individuals who were 100 years or older at the time of the examination. Patient and echocardiogram characteristics, management decisions based on echocardiography, and mortality were documented. Results 114 centenarians had echocardiograms, with ages ranging from 100 to 107 years （101 - 1.4 years）. In 82 of the centenarians evaluated （72%）, no changes in management occurred as a consequence of the echocardiogram. From all management changes directly related to the echocardiogram, 81% （n = 26） of these corresponded to medication adjustments; interventional or surgical procedures followed the echocardiogram only in 4% （n = 5） of the total number of centenarians. Echocardiogram-based changes in management were only significant in patients that were referred for congestive heart failure （P = 0.02）. After the echocardiogram was performed, 1-month and 1-year mortality were 15% and 47%, respectively. The median survival after the echocardiogram was obtained was 13 months （range 0.03 to 145 months）, with no difference if there was a change or no change in manage- ment （P = 0.21）. Conclusions Among centenarians undergoing echocardiography, despite additional diagnostic information, echocardio- grams in centenarians influence management in a minority of cases, most commonly in the form of medication changes for treatment of heart failure. A significant proportion of centenarians are deceased within a year of undergoing echocardiographic assessment. These findings may question the overall utility of echocardiography in these late survivors.
