IEEE 802.11 distributed coordination function (DCF) can alleviate the collision and hidden station problem, but it doesn’t differentiate traffic categories (TC). Therefore, it can’t provide sufficient QoS support fo...IEEE 802.11 distributed coordination function (DCF) can alleviate the collision and hidden station problem, but it doesn’t differentiate traffic categories (TC). Therefore, it can’t provide sufficient QoS support for different traffic categories. Recently, a new contention-based enhanced distributed channel access (EDCA) scheme was proposed which provides a probabilistic QoS support. In this paper, an adaptive EDCA scheme with QoS guarantee for mobile ad hoc networks (MANETs) is proposed. In this scheme, the EDCA scheme and the token bucket algorithm (TBA) are combined to adjust the contention window (CW). Our scheme provides the traffic differentiation.展开更多
Current guidelines encourage large studies in a diverse population to establish normal reference ranges for three-dimensional(3D)echocardiography for different ethnic groups.This study was designed to establish the no...Current guidelines encourage large studies in a diverse population to establish normal reference ranges for three-dimensional(3D)echocardiography for different ethnic groups.This study was designed to establish the normal values of 3D-left ventricular(LV)and left atrial(LA)volume and function in a nationwide,population-based cohort of healthy Han Chinese adults.A total of 1117 healthy volunteers aged 18–89 years were enrolled from 28 collaborating laboratories in China.Two sets of 3D echocardiographic instruments were used,and full-volume echocardiographic images were recorded and transmitted to a core laboratory for image analysis with a vendor-independent off-line workstation.Finally,866 volunteers(mean age of 48.4 years,402 men)were qualified for final analysis.Most parameters exhibited substantial differences between different sex and age groups,even after indexation by body surface area.The normal ranges of 3D-LV and 3D-LA volume and function differed from those recommended by the American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines,presented by the World Alliance Societies of Echocardiography(WASE)study,and from the 2D values in the EMINCA study.The normal reference values of 3D echocardiography-derived LV and LA volume and function were established for the first time in healthy Han Chinese adults.Normal ranges of 3D-LV and 3D-LA echocardiographic measurements stratified with sex,age,and race should be recommended for clinical applications.展开更多
文摘IEEE 802.11 distributed coordination function (DCF) can alleviate the collision and hidden station problem, but it doesn’t differentiate traffic categories (TC). Therefore, it can’t provide sufficient QoS support for different traffic categories. Recently, a new contention-based enhanced distributed channel access (EDCA) scheme was proposed which provides a probabilistic QoS support. In this paper, an adaptive EDCA scheme with QoS guarantee for mobile ad hoc networks (MANETs) is proposed. In this scheme, the EDCA scheme and the token bucket algorithm (TBA) are combined to adjust the contention window (CW). Our scheme provides the traffic differentiation.
文摘Current guidelines encourage large studies in a diverse population to establish normal reference ranges for three-dimensional(3D)echocardiography for different ethnic groups.This study was designed to establish the normal values of 3D-left ventricular(LV)and left atrial(LA)volume and function in a nationwide,population-based cohort of healthy Han Chinese adults.A total of 1117 healthy volunteers aged 18–89 years were enrolled from 28 collaborating laboratories in China.Two sets of 3D echocardiographic instruments were used,and full-volume echocardiographic images were recorded and transmitted to a core laboratory for image analysis with a vendor-independent off-line workstation.Finally,866 volunteers(mean age of 48.4 years,402 men)were qualified for final analysis.Most parameters exhibited substantial differences between different sex and age groups,even after indexation by body surface area.The normal ranges of 3D-LV and 3D-LA volume and function differed from those recommended by the American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines,presented by the World Alliance Societies of Echocardiography(WASE)study,and from the 2D values in the EMINCA study.The normal reference values of 3D echocardiography-derived LV and LA volume and function were established for the first time in healthy Han Chinese adults.Normal ranges of 3D-LV and 3D-LA echocardiographic measurements stratified with sex,age,and race should be recommended for clinical applications.
