The unsupported sleeper can change the load characteristics of ballast particles and thus affect the dynamic stability of a ballasted bed.In this work,a laboratory test was constructed on a ballasted track containing ...The unsupported sleeper can change the load characteristics of ballast particles and thus affect the dynamic stability of a ballasted bed.In this work,a laboratory test was constructed on a ballasted track containing unsupported sleepers.The ballasted track was excited by a wheelset,and the influence of unsupported sleepers on the dynamic stability of a ballasted bed was studied.The results show that the main frequency of the sleeper vibration appeared at 670 Hz,and the first-order rigid vibration mode at the frequency of 101 Hz had a significant effect on the condition without the unsupported sleeper.When the sleepers were continuously unsupported,the vibration damping effect of ballasted bed within the frequency range of 0–450 Hz was better than that at higher frequencies.Within the frequency range of 70–250 Hz,the vibration damping effect of the ballasted bed with unsupported sleepers was better than that without the unsupported sleeper.Owing to the excitation from the wheelset impact,the lateral resistance of the ballasted bed with unsupported sleepers whose hanging heights were 30,60,and 90 mm increased by 37.43%,12.25%,and 18.23%,respectively,while the lateral resistance of the ballasted bed without the unsupported sleeper remained basically unchanged.The unsupported sleeper could increase the difference in the quality of the ballasted bed between two adjacent sleepers.In addition,test results show that the hanging height of the unsupported sleeper had little effect on the lateral resistance of a ballasted bed without external excitation,but had an obvious effect on the rate of change of the lateral resistance of a ballasted bed and the acceleration amplitude of the sleeper vibration under the wheelset impact.展开更多
Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining wal...Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.展开更多
A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests wer...A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.展开更多
Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads....Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads.Three models of typical bedded rock slopes(BRSs),i.e.gently(GIS),moderately(MIS),and steeply(SIS)inclined slopes,were proposed according to field investigations.The dynamic response mechanism and stability of the BRSs,affected by the rock mass deterioration of the HFB,were investigated by the shaking table test and the universal distinct element code(UDEC)simulation.Specifically,the amplification coefficient of the peak ground acceleration(PGA)of the slope was gradually attenuated under multiple seismic loads,and the acceleration response showed obvious“surface effect”and“elevation effect”in the horizontal and vertical directions,respectively.The“S-type”cubic function and“steep-rise type”exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves(low seismic waves)and high seismic waves,respectively.According to the dynamic responses of the acceleration,cumulative displacement,rock pressure,pore water pressure,damping ratio,natural frequency,stability coefficient,and sliding velocity of the slope,the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized,and the numerical and experimental results were compared.Considering the dynamic effects of the slope height(SH),slope angle(SA),bedding plane thickness(BPT),dip angle of the bedding plane(DABP),dynamic load amplitude(DLA),dynamic load frequency(DLF),height of water level of the hydro-fluctuation belt(HWLHFB),degradation range of the hydro-fluctuation belt(DRHFB),and degradation shape of the hydro-fluctuation belt(DSHFB),the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method(OAM)was DLA>DRHFB>SA>SH>DLF>HWLHFB>DSHFB>DABP>BPT.展开更多
Objective:To determine the preventive effects of curcumin on peroxidative damage under two bed rest conditions.Methods:20 healthy male(10 with curcumin and 10 without curcumin ) volunteers were selected.They were stud...Objective:To determine the preventive effects of curcumin on peroxidative damage under two bed rest conditions.Methods:20 healthy male(10 with curcumin and 10 without curcumin ) volunteers were selected.They were studied before,during,and just on bed rest conditions at -6°head-down-tilt(HDT) bed rest and bed rest position(BD) for 10 days.We measured the salivary and serum oxidative markers such as Malonaldehyde,8-hydroxydeoxyguanosine, vitamin C and E just before HDT & BD.during HDT & BD experiment,and in course time of recovery with curcumin and without curcumin groups.Results:The values of serum and salivary vitamin C & E showed statistically significant decrease in both bed rest conditions as compared to those of the conditions before and during the recovery stage.However,these levels were not significantly lowered in curcumin groups in contrast to the groups without curcumin (P】0.05).MDA and 8-OHdG levels showed significant increase in simulating microgravity and zero gravity conditions as compared to those before and in the recovery stage.However,these levels were lower in curcumin groups in contrast to the groups without curcumin(P【0.05).Serum and salivary correlation analysis revealed a strong and highly significant correlation for MDA. vitamin C & E and 8 dihydro-2 deoxyguanosine(8-OHdG) in the conditions before,during and in the recovery periods in both bed rest conditions.Since saliva collection is easy and noninvasive, measurements of salivary marker levels may prove to be useful in the space research. Conclusions:Curcumin prevents peroxidative damage in both bed rest conditions.Further study is required on antioxidation actions of curcumin in space microgravity conditions.展开更多
Objective:To investigate the safety of relieving bed restriction in hepatic arterial infusion chemotherapy(HAIC)and its effects on patient comfort.Methods:A prospective study was conducted.Patients with malignant live...Objective:To investigate the safety of relieving bed restriction in hepatic arterial infusion chemotherapy(HAIC)and its effects on patient comfort.Methods:A prospective study was conducted.Patients with malignant liver tumors,who met the enrollment criteria,were randomly divided into experimental and control groups.During HAIC treatment,the patients in the experimental group,who were not confined to bed and could get out of bed,used electronic injection pumps to infuse chemotherapy drugs.The patients in the control group,who were strictly confined to bed and prohibited from getting out of bed,used infusion pumps to infuse chemotherapy drugs.The complications of the two groups were observed.The Christenson standard improved method was used to evaluate the bleeding and hematoma of limbs on the operation side.The Kolcaba General Comfort Questionnaire(GCQ)and Barthel Index(BI)were used to evaluate the two groups.Results:Ninety patients with malignant liver tumors were enrolled,including 53 with primary liver cancer and 37 with colorectal liver metastasis.There were 70 males and 20 females,aged 41-81 years old,with an average age of 61.6±9.248 years old.There were 60 patients in the experimental group and 30 patients in the control group.All patients underwent HAIC.The study showed that,during the treatment period,there were 3 cases of postoperative puncture point hematoma formation in the two groups,including 2 cases in the experimental group(2/60,3.3%)and 1 case in the control group(1/30,3.3%).The difference was not statistically significant(p>0.05).There were 5 cases of postoperative puncture point bleeding,including 4 cases in the experimental group(4/60,6.7%)and 1 case in the control group(1/30,3.3%),and the difference was not statistically significant(p>0.05).A total of 23 cases,with 6 cases in the experimental group(6/60,10%)and 17 cases in the control group(17/30,56.7%),complained of back pain after the operation,and the difference was statistically significant(p<0.05).Twenty-one cases complained of poor defecation after the operation,including 10 cases in the experimental group(10/60,16.7%)and 11 cases in the control group(11/30,36.7%).The difference was statistically significant(p<0.05).During the period of infusion chemotherapy,the two groups of patients had there was a significant difference between the two groups in terms of comfort status(GCQ)(88.78±6.705,78.47±9.519,p<0.001)and self-care ability(BI)(74.25±9.152,66.83±6.628,p<0.001).Conclusion:During HAIC treatment,getting out of bed is safe and reliable and can increase the patients’comfort and self-care ability.Hence,it merits clinical application.展开更多
Considering the maternal risk for both short- and long-term disability imposed by activity restriction, it is of great concern that the antepartum symptoms of bed rest are still evident in the postpartum period. The b...Considering the maternal risk for both short- and long-term disability imposed by activity restriction, it is of great concern that the antepartum symptoms of bed rest are still evident in the postpartum period. The benefits of bed-rest-exercise may alleviate or even prevent physiological distresses or deconditioning associated with activity restriction, thus, eliminating or stabilizing, factors that may augment existing complications. This is the first study to investigate the feasibility of incorporating a bed-rest exercise program in a specific hospitalized twin pregnancy case. The maternal physiological responses of heart rate, blood pressure and uterine contractions to a four week bed-rest resistance program were measured in a woman hospitalized due to complications during her twin pregnancy. A second participant (same diagnoses) was included as a control. The bed-rest-exercise reduced the degree of swelling in the lower extremities, promoted more energy during the day and a better night’s sleep. There were no significant differences in uterine contractions pre vs. post protocol and all babies were born healthy.展开更多
<strong>Objective:</strong> Against a background of the two-child policy in China, the objective is to explore the effects of lower limb strengthening exercises on hospitalized pregnant women put on bed re...<strong>Objective:</strong> Against a background of the two-child policy in China, the objective is to explore the effects of lower limb strengthening exercises on hospitalized pregnant women put on bed rest for prevention of miscarriage. <strong>Method:</strong> Sixty cases of pregnant women admitted to the Department of Obstetrics in one of the highest ranking hospitals in Guangzhou, China, during the period from November 2018 to December 2019 for the purpose of preventing miscarriage were selected. They were divided into an experimental group and a control group of 30 cases each. The control group was put under routine care while the intervention group conducted lower limb muscle strengthening exercise on top of the routine care. After the intervention, the conditions of lower limbs, the psychological states and the results of pregnancy for the two groups were compared. <strong>Results: </strong>After the intervention, the scores of the experimental group in anxiety, depression and postpartum depression were lower and leg circumferences were smaller compared to the control group. The difference is statistically significant (<em>P</em> < 0.05). The experimental group had longer gestation than the control group and was able to get out of bed earlier than the control group after delivery, with statistically significant difference (<em>P</em> < 0.05). <strong>Conclusion:</strong> Lower limb muscle strengthening exercises can effectively improve the physiological and psychological states of pregnant women hospitalized for prevention of miscarriage and promote their postpartum recovery.展开更多
Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of rai...Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km1,and the computational efficiency of other indexes is 5 s$km1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.展开更多
基金The present work was supported by the National Natural Science Foundation of China(No.52008395).
文摘The unsupported sleeper can change the load characteristics of ballast particles and thus affect the dynamic stability of a ballasted bed.In this work,a laboratory test was constructed on a ballasted track containing unsupported sleepers.The ballasted track was excited by a wheelset,and the influence of unsupported sleepers on the dynamic stability of a ballasted bed was studied.The results show that the main frequency of the sleeper vibration appeared at 670 Hz,and the first-order rigid vibration mode at the frequency of 101 Hz had a significant effect on the condition without the unsupported sleeper.When the sleepers were continuously unsupported,the vibration damping effect of ballasted bed within the frequency range of 0–450 Hz was better than that at higher frequencies.Within the frequency range of 70–250 Hz,the vibration damping effect of the ballasted bed with unsupported sleepers was better than that without the unsupported sleeper.Owing to the excitation from the wheelset impact,the lateral resistance of the ballasted bed with unsupported sleepers whose hanging heights were 30,60,and 90 mm increased by 37.43%,12.25%,and 18.23%,respectively,while the lateral resistance of the ballasted bed without the unsupported sleeper remained basically unchanged.The unsupported sleeper could increase the difference in the quality of the ballasted bed between two adjacent sleepers.In addition,test results show that the hanging height of the unsupported sleeper had little effect on the lateral resistance of a ballasted bed without external excitation,but had an obvious effect on the rate of change of the lateral resistance of a ballasted bed and the acceleration amplitude of the sleeper vibration under the wheelset impact.
基金supported by the Fujian Science Foundation for Outstanding Youth(Grant No.2023J06039)the National Natural Science Foundation of China(Grant No.41977259 and No.U2005205)Fujian Province natural resources science and technology innovation project(Grant No.KY-090000-04-2022-019)。
文摘Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.
基金supported by the National Natural Science Foundation of China (Grant No.52364004)the Basic Research Project of Guizhou University (Grant No.[2023]40)support by the Helmholtz Association’s Initiative and Networking Fund for the Helmholtz Young Investigator Group ARES (Contract No.VH-NG-1516).
文摘A comprehensive understanding of shale’s bedding anisotropy is crucial for shale-related engineering activities,such as hydraulic fracturing,drilling and underground excavation.In this study,seven Brazilian tests were conducted on shale samples at different bedding orientations with respect to the loading direction(0°,45°and 90°)and the disc end face(0°,45°and 90°).An acoustic emission(AE)system was employed to capture the evolution of damage and the temporal-spatial distribution of microcracks under splitting-tensile stress.The results show that the Brazilian tensile strength decreases with increasing bedding inclination with respect to the disc end face,while it increases with the angle between bedding and loading directions.Increasing the bedding inclination with respect to the end face facilitates the reduction in b value and enhances the shale’s resistance to microcrack growth during the loading process.Misalignment between the bedding orientation and the end face suppresses the growth of mixed tensile-shear microcracks,while reducing the bedding angle relative to the loading direction is beneficial for creating mixed tensile-shear and tensile cracks.The observed microscopic failure characteristics are attributed to the competing effects of bedding activation and breakage of shale matrix at different bedding inclinations.The temporal-spatial distribution of microcracks,characterized by AE statistics including the correlation dimension and spatial correlation length,illustrates that the fractal evolution of microcracks is independent of bedding anisotropy,whereas the spatial distribution shows a stronger correlation.The evolution features of correlation dimension and spatial correlation length could be potentially used as precursors for shale splitting failure.These findings may be useful for predicting rock mass instability and analyzing the causes of catastrophic rupture.
基金the China Postdoctoral Science Foundation(Grant No.2023M730432)the Special Funding for Chongqing Postdoctoral Research Project(Grant No.2022CQBSHTB1010)the Chongqing Postdoctoral Science Foundation(Grant No.CSTB2023NSCQ-BHX0223).
文摘Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads.Three models of typical bedded rock slopes(BRSs),i.e.gently(GIS),moderately(MIS),and steeply(SIS)inclined slopes,were proposed according to field investigations.The dynamic response mechanism and stability of the BRSs,affected by the rock mass deterioration of the HFB,were investigated by the shaking table test and the universal distinct element code(UDEC)simulation.Specifically,the amplification coefficient of the peak ground acceleration(PGA)of the slope was gradually attenuated under multiple seismic loads,and the acceleration response showed obvious“surface effect”and“elevation effect”in the horizontal and vertical directions,respectively.The“S-type”cubic function and“steep-rise type”exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves(low seismic waves)and high seismic waves,respectively.According to the dynamic responses of the acceleration,cumulative displacement,rock pressure,pore water pressure,damping ratio,natural frequency,stability coefficient,and sliding velocity of the slope,the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized,and the numerical and experimental results were compared.Considering the dynamic effects of the slope height(SH),slope angle(SA),bedding plane thickness(BPT),dip angle of the bedding plane(DABP),dynamic load amplitude(DLA),dynamic load frequency(DLF),height of water level of the hydro-fluctuation belt(HWLHFB),degradation range of the hydro-fluctuation belt(DRHFB),and degradation shape of the hydro-fluctuation belt(DSHFB),the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method(OAM)was DLA>DRHFB>SA>SH>DLF>HWLHFB>DSHFB>DABP>BPT.
文摘Objective:To determine the preventive effects of curcumin on peroxidative damage under two bed rest conditions.Methods:20 healthy male(10 with curcumin and 10 without curcumin ) volunteers were selected.They were studied before,during,and just on bed rest conditions at -6°head-down-tilt(HDT) bed rest and bed rest position(BD) for 10 days.We measured the salivary and serum oxidative markers such as Malonaldehyde,8-hydroxydeoxyguanosine, vitamin C and E just before HDT & BD.during HDT & BD experiment,and in course time of recovery with curcumin and without curcumin groups.Results:The values of serum and salivary vitamin C & E showed statistically significant decrease in both bed rest conditions as compared to those of the conditions before and during the recovery stage.However,these levels were not significantly lowered in curcumin groups in contrast to the groups without curcumin (P】0.05).MDA and 8-OHdG levels showed significant increase in simulating microgravity and zero gravity conditions as compared to those before and in the recovery stage.However,these levels were lower in curcumin groups in contrast to the groups without curcumin(P【0.05).Serum and salivary correlation analysis revealed a strong and highly significant correlation for MDA. vitamin C & E and 8 dihydro-2 deoxyguanosine(8-OHdG) in the conditions before,during and in the recovery periods in both bed rest conditions.Since saliva collection is easy and noninvasive, measurements of salivary marker levels may prove to be useful in the space research. Conclusions:Curcumin prevents peroxidative damage in both bed rest conditions.Further study is required on antioxidation actions of curcumin in space microgravity conditions.
文摘Objective:To investigate the safety of relieving bed restriction in hepatic arterial infusion chemotherapy(HAIC)and its effects on patient comfort.Methods:A prospective study was conducted.Patients with malignant liver tumors,who met the enrollment criteria,were randomly divided into experimental and control groups.During HAIC treatment,the patients in the experimental group,who were not confined to bed and could get out of bed,used electronic injection pumps to infuse chemotherapy drugs.The patients in the control group,who were strictly confined to bed and prohibited from getting out of bed,used infusion pumps to infuse chemotherapy drugs.The complications of the two groups were observed.The Christenson standard improved method was used to evaluate the bleeding and hematoma of limbs on the operation side.The Kolcaba General Comfort Questionnaire(GCQ)and Barthel Index(BI)were used to evaluate the two groups.Results:Ninety patients with malignant liver tumors were enrolled,including 53 with primary liver cancer and 37 with colorectal liver metastasis.There were 70 males and 20 females,aged 41-81 years old,with an average age of 61.6±9.248 years old.There were 60 patients in the experimental group and 30 patients in the control group.All patients underwent HAIC.The study showed that,during the treatment period,there were 3 cases of postoperative puncture point hematoma formation in the two groups,including 2 cases in the experimental group(2/60,3.3%)and 1 case in the control group(1/30,3.3%).The difference was not statistically significant(p>0.05).There were 5 cases of postoperative puncture point bleeding,including 4 cases in the experimental group(4/60,6.7%)and 1 case in the control group(1/30,3.3%),and the difference was not statistically significant(p>0.05).A total of 23 cases,with 6 cases in the experimental group(6/60,10%)and 17 cases in the control group(17/30,56.7%),complained of back pain after the operation,and the difference was statistically significant(p<0.05).Twenty-one cases complained of poor defecation after the operation,including 10 cases in the experimental group(10/60,16.7%)and 11 cases in the control group(11/30,36.7%).The difference was statistically significant(p<0.05).During the period of infusion chemotherapy,the two groups of patients had there was a significant difference between the two groups in terms of comfort status(GCQ)(88.78±6.705,78.47±9.519,p<0.001)and self-care ability(BI)(74.25±9.152,66.83±6.628,p<0.001).Conclusion:During HAIC treatment,getting out of bed is safe and reliable and can increase the patients’comfort and self-care ability.Hence,it merits clinical application.
文摘Considering the maternal risk for both short- and long-term disability imposed by activity restriction, it is of great concern that the antepartum symptoms of bed rest are still evident in the postpartum period. The benefits of bed-rest-exercise may alleviate or even prevent physiological distresses or deconditioning associated with activity restriction, thus, eliminating or stabilizing, factors that may augment existing complications. This is the first study to investigate the feasibility of incorporating a bed-rest exercise program in a specific hospitalized twin pregnancy case. The maternal physiological responses of heart rate, blood pressure and uterine contractions to a four week bed-rest resistance program were measured in a woman hospitalized due to complications during her twin pregnancy. A second participant (same diagnoses) was included as a control. The bed-rest-exercise reduced the degree of swelling in the lower extremities, promoted more energy during the day and a better night’s sleep. There were no significant differences in uterine contractions pre vs. post protocol and all babies were born healthy.
文摘<strong>Objective:</strong> Against a background of the two-child policy in China, the objective is to explore the effects of lower limb strengthening exercises on hospitalized pregnant women put on bed rest for prevention of miscarriage. <strong>Method:</strong> Sixty cases of pregnant women admitted to the Department of Obstetrics in one of the highest ranking hospitals in Guangzhou, China, during the period from November 2018 to December 2019 for the purpose of preventing miscarriage were selected. They were divided into an experimental group and a control group of 30 cases each. The control group was put under routine care while the intervention group conducted lower limb muscle strengthening exercise on top of the routine care. After the intervention, the conditions of lower limbs, the psychological states and the results of pregnancy for the two groups were compared. <strong>Results: </strong>After the intervention, the scores of the experimental group in anxiety, depression and postpartum depression were lower and leg circumferences were smaller compared to the control group. The difference is statistically significant (<em>P</em> < 0.05). The experimental group had longer gestation than the control group and was able to get out of bed earlier than the control group after delivery, with statistically significant difference (<em>P</em> < 0.05). <strong>Conclusion:</strong> Lower limb muscle strengthening exercises can effectively improve the physiological and psychological states of pregnant women hospitalized for prevention of miscarriage and promote their postpartum recovery.
基金funded by the National Key R&Dprogram of China[Grant No.2022YFB2603302]the Science and Technology Research and Development Program of China State Railway Group Co.,Ltd[Grant No.K2022G015]the Fund Project of China Academy of Railway Sciences Corporation Limited[Grant No.2022YJ305].
文摘Purpose–In this paper,a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks,respectively,for a quantitative evaluation of the condition of railway ballast bed.Design/methodology/approach–Based on original radar signals,the time–frequency characteristics of radar signals were analyzed,five ballast bed condition characteristic indexes were proposed,including the frequency domain integral area,scanning area,number of intersections with the time axis,number of timedomain inflection points and amplitude envelope obtained by Hilbert transform,and the effectiveness and sensitivity of the indexes were analyzed.Findings–The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm,which meets the requirements of ballast bed detection.Compared with clean ballast bed,the values of the five indexes of fouled ballast bed are larger,and the five indexes could effectively show the condition of the ballast bed.The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s$km1,and the computational efficiency of other indexes is 5 s$km1.The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive,followed by scanning area.The number of intersections with the time axis in the bridge sections was the most sensitive,followed by the scanning area.The scanning area can adapt to different substructures such as subgrade,bridges and tunnels,with high comprehensive sensitivity.Originality/value–The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.