Pedicle screw placement is an advanced posterior fixation technique that can provide patients with great biomechanical benefits. However, the morphology of the vertebrae is complex and it is very difficult to insert s...Pedicle screw placement is an advanced posterior fixation technique that can provide patients with great biomechanical benefits. However, the morphology of the vertebrae is complex and it is very difficult to insert screws without penetrating the cortex. Thus, new techniques for improving the accuracy of pedicle screw placement and safety are required. Herein,展开更多
Research on the identity of genes and their relationship with traits of economic importance in farm animals could assist in the selection of livestock. In this study, the polymorphisms of insulin-like growth factor 1 ...Research on the identity of genes and their relationship with traits of economic importance in farm animals could assist in the selection of livestock. In this study, the polymorphisms of insulin-like growth factor 1 （IGF1） gene in 561 goats of ten breeds were detected by polymerase chain reaction （PCR）-single strand conformation polymorphism （SSCP） and their association with litter size and birth weight in three breeds were investigated. The effects of IGF1 polymorphisms on the breeding value for litter size and birth weight were examined using least square methods. Two deletions （CA） were detected in the microsatellite and two mutations （A1637G, T1640C） were found in 5′-flanking regulatory region. No significant association between the polymorphisms in 5′-flanking region of IGF1 and birth weight was found in the three breeds of goats. In Gulin Ma goats, two polymorphisms were found to affect litter size traits. In Chuandong White goats and Guizhou White goats, no significant difference （P0.05） in litter size between goats carrying different genotypes was observed. Further evaluation and confirmation studies in more goat populations with larger sample sizes are necessary.展开更多
Background This study aimed to explore the imaging characteristics,diversity and changing trend in CT scans of pediatric patients infected with Delta-variant strain by studying imaging features of children infected wi...Background This study aimed to explore the imaging characteristics,diversity and changing trend in CT scans of pediatric patients infected with Delta-variant strain by studying imaging features of children infected with Delta and comparing the results to those of children with original COVID-19.Methods A retrospective,comparative analysis of initial chest CT manifestations between 63 pediatric patients infected with Delta variant in 2021 and 23 pediatric patients with COVID-19 in 2020 was conducted.Corresponding imaging features were analyzed.In addition,the changing trend in imaging features of COVID-19 Delta-variant cases were explored by evaluating the initial and follow-up CT scans.Results Among 63 children with Delta-variant COVID-19 in 2021,34(53.9%)showed positive chest CT presentation;and their CT score(1.10±1.41)was signifcantly lower than that in 2020(2.56±3.5)(P=0.0073).Lesion distribution:lung lesions of Delta cases appear mainly in the lower lungs on both sides.Most children had single lobe involvement(18 cases,52.9%),14(41.2%)in the right lung alone,and 14(41.2%)in both lungs.A majority of Delta cases displayed initially ground glass(23 cases,67.6%)and nodular shadows(13 cases,38.2%)in the frst CT scan,with few extrapulmonary manifestations.The 34 children with abnormal chest CT for the frst time have a total of 92 chest CT examinations.These children showed a statistically signifcant diference between the 0-3 day group and the 4-7 day group(P=0.0392)and a signifcant diference between the 4-7 day group and the more than 8 days group(P=0.0003).Conclusions The early manifestations of COVID-19 in children with abnormal imaging are mostly small subpleural nodular ground glass opacity.The changes on the Delta-variant COVID-19 chest CT were milder than the original strain.The lesions reached a peak on CT in 4-7 days and quickly improved and absorbed after a week.Dynamic CT re-examination can achieve a good prognosis.展开更多
Background The aim of this study was to analyze the clinical characteristics of 66 pediatric patients with B.l.617.2(Delta)variant of coronavirus disease 2019(COVID-19).Methods Sixty-six pediatric patients with B.1.61...Background The aim of this study was to analyze the clinical characteristics of 66 pediatric patients with B.l.617.2(Delta)variant of coronavirus disease 2019(COVID-19).Methods Sixty-six pediatric patients with B.1.617.2(Delta)variant of COVID-19 admitted to the hospital from July to August 2021 were classified into mild(n=41)and moderate groups(n=25).Clinical characteristics,laboratory data and dynamic trends in different time periods were analyzed retrospectively.Results There were no statistically significant differences in age,gender ratios and clinical symptoms between the mild group and the moderate group.All the patients in the moderate group had clusters of onsets,and the incubation period was shorter than that of the mild group.Within 24 hours of admission,the levels of erythrocyte sedimentation rate,cardiac troponin I,D-dimer in the moderate group were higher than that in the mild group(P<0.05).The titers of immunoglobulin(Ig)G and IgM antibodies gradually increased after disease onset.Thirty-five(53.03%)children were tested positive for antibodies in 4-12 days.IgG increased gradually,while IgM decreased obviously in about 15 days after disease onset.The cycle threshold values of open reading frame lab and nucleocapsid protein gene in the severe acute respiratory syndrome coronavirus 2 genomes in creased gradually on the 3rd,6th,9th,and 12th days after disease onset,compared with those in day 0.Conclusions The symptoms of children with B.l.617.2(Delta)variant of COVID-19 were mild.The description and analysis of the clinical characteristics and laboratory data can help medical stafiF to evaluate the condition of children with COVID-19 and to accumulate more clinical experience.展开更多
In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core co...In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core component of the preload system, is developed using giant magnetostrictive material （GMM） with a hole. The pretightening force of the CGMA is determined by testing. And the magnetic circuit analysis method is introduced to calculate magnetic field intensity of the actuator with a ball screw shaft. To suppress the thermal effects on the magnetostrictive outputs, an oil cooling method which can directly cool the heat source is adopted. A CGMA test platform is established and the static and dynamic output characteristics are respectively studied. The experimental results indicate that the CGMA has good linearity and no double-frequency effect under the bias magnetic field and the output accuracy of the CGMA is significantly improved with cooling measures. Although the output decreased with screw shaft through the actuator, the performance of CGMA meets the design requirements for ball screw preload with output displacement more than 26 μm and force up to 6200 N. The development of a CGMA will provide a new approach for automatic adjustment of double-nut ball screw preload.展开更多
BACKGROUND In robot-assisted(RA)spine surgery,the relationship between the surgical outcome and the learning curve remains to be evaluated.AIM To analyze the learning curve of RA pedicle screw fixation(PSF)through fit...BACKGROUND In robot-assisted(RA)spine surgery,the relationship between the surgical outcome and the learning curve remains to be evaluated.AIM To analyze the learning curve of RA pedicle screw fixation(PSF)through fitting the operation time curve based on the cumulative summation method.METHODS RA PSFs that were initially completed by two surgeons at the Beijing Jishuitan Hospital from July 2016 to March 2019 were analyzed retrospectively.Based on the cumulative sum of the operation time,the learning curves of the two surgeons were drawn and fit to polynomial curves.The learning curve was divided into the early and late stages according to the shape of the fitted curve.The operation time and screw accuracy were compared between the stages.RESULTS The turning point of the learning curves from Surgeons A and B appeared in the 18th and 17th cases,respectively.The operation time[150(128,188)min vs 120(105,150)min,P=0.002]and the screw accuracy(87.50%vs 96.30%,P=0.026)of RA surgeries performed by Surgeon A were significantly improved after he completed 18 cases.In the case of Surgeon B,the operation time(177.35±28.18 min vs 150.00±34.64 min,P=0.024)was significantly reduced,and the screw accuracy(91.18%vs 96.15%,P=0.475)was slightly improved after the surgeon completed 17 RA surgeries.CONCLUSION After completing 17 to 18 cases of RA PSFs,surgeons can pass the learning phase of RA technology.The operation time is reduced afterward,and the screw accuracy shows a trend of improvement.展开更多
文摘Pedicle screw placement is an advanced posterior fixation technique that can provide patients with great biomechanical benefits. However, the morphology of the vertebrae is complex and it is very difficult to insert screws without penetrating the cortex. Thus, new techniques for improving the accuracy of pedicle screw placement and safety are required. Herein,
基金supported by the earmarked fund for Modern Agro-Industry Technology Research System of China (nycytx-39)the Natural Science Foundation Project of CQ CSTC, Chongqing City, China (CSTC, 2009BA1066)
文摘Research on the identity of genes and their relationship with traits of economic importance in farm animals could assist in the selection of livestock. In this study, the polymorphisms of insulin-like growth factor 1 （IGF1） gene in 561 goats of ten breeds were detected by polymerase chain reaction （PCR）-single strand conformation polymorphism （SSCP） and their association with litter size and birth weight in three breeds were investigated. The effects of IGF1 polymorphisms on the breeding value for litter size and birth weight were examined using least square methods. Two deletions （CA） were detected in the microsatellite and two mutations （A1637G, T1640C） were found in 5′-flanking regulatory region. No significant association between the polymorphisms in 5′-flanking region of IGF1 and birth weight was found in the three breeds of goats. In Gulin Ma goats, two polymorphisms were found to affect litter size traits. In Chuandong White goats and Guizhou White goats, no significant difference （P0.05） in litter size between goats carrying different genotypes was observed. Further evaluation and confirmation studies in more goat populations with larger sample sizes are necessary.
基金This study was supported by the China Postdoctoral Science Foundation 2020M681674(to Xuhua Ge)The Nanjing Medical Science and Technique Development Foundation(No.YKK20130)(to Zhuo Li)This work was reviewed and approved by the Medical Ethical Committee of Second Hospital of Nanjing(approval number 2020-LS-ky003).
文摘Background This study aimed to explore the imaging characteristics,diversity and changing trend in CT scans of pediatric patients infected with Delta-variant strain by studying imaging features of children infected with Delta and comparing the results to those of children with original COVID-19.Methods A retrospective,comparative analysis of initial chest CT manifestations between 63 pediatric patients infected with Delta variant in 2021 and 23 pediatric patients with COVID-19 in 2020 was conducted.Corresponding imaging features were analyzed.In addition,the changing trend in imaging features of COVID-19 Delta-variant cases were explored by evaluating the initial and follow-up CT scans.Results Among 63 children with Delta-variant COVID-19 in 2021,34(53.9%)showed positive chest CT presentation;and their CT score(1.10±1.41)was signifcantly lower than that in 2020(2.56±3.5)(P=0.0073).Lesion distribution:lung lesions of Delta cases appear mainly in the lower lungs on both sides.Most children had single lobe involvement(18 cases,52.9%),14(41.2%)in the right lung alone,and 14(41.2%)in both lungs.A majority of Delta cases displayed initially ground glass(23 cases,67.6%)and nodular shadows(13 cases,38.2%)in the frst CT scan,with few extrapulmonary manifestations.The 34 children with abnormal chest CT for the frst time have a total of 92 chest CT examinations.These children showed a statistically signifcant diference between the 0-3 day group and the 4-7 day group(P=0.0392)and a signifcant diference between the 4-7 day group and the more than 8 days group(P=0.0003).Conclusions The early manifestations of COVID-19 in children with abnormal imaging are mostly small subpleural nodular ground glass opacity.The changes on the Delta-variant COVID-19 chest CT were milder than the original strain.The lesions reached a peak on CT in 4-7 days and quickly improved and absorbed after a week.Dynamic CT re-examination can achieve a good prognosis.
基金supported by the China Postdoctoral Science Foundation(No.2020M681674,to GXH)the Nanjing Medical Science and Technique Development Foundation(No.YKK20130,to LZ).
文摘Background The aim of this study was to analyze the clinical characteristics of 66 pediatric patients with B.l.617.2(Delta)variant of coronavirus disease 2019(COVID-19).Methods Sixty-six pediatric patients with B.1.617.2(Delta)variant of COVID-19 admitted to the hospital from July to August 2021 were classified into mild(n=41)and moderate groups(n=25).Clinical characteristics,laboratory data and dynamic trends in different time periods were analyzed retrospectively.Results There were no statistically significant differences in age,gender ratios and clinical symptoms between the mild group and the moderate group.All the patients in the moderate group had clusters of onsets,and the incubation period was shorter than that of the mild group.Within 24 hours of admission,the levels of erythrocyte sedimentation rate,cardiac troponin I,D-dimer in the moderate group were higher than that in the mild group(P<0.05).The titers of immunoglobulin(Ig)G and IgM antibodies gradually increased after disease onset.Thirty-five(53.03%)children were tested positive for antibodies in 4-12 days.IgG increased gradually,while IgM decreased obviously in about 15 days after disease onset.The cycle threshold values of open reading frame lab and nucleocapsid protein gene in the severe acute respiratory syndrome coronavirus 2 genomes in creased gradually on the 3rd,6th,9th,and 12th days after disease onset,compared with those in day 0.Conclusions The symptoms of children with B.l.617.2(Delta)variant of COVID-19 were mild.The description and analysis of the clinical characteristics and laboratory data can help medical stafiF to evaluate the condition of children with COVID-19 and to accumulate more clinical experience.
基金Project(51475267) supported by the National Natural Science Foundation of China
文摘In order to achieve automatic adjustment of the double-nut ball screw preload, a magnetostrictive ball screw preload system is proposed. A new cylindrical giant magnetostrictive actuator （CGMA）, which is the core component of the preload system, is developed using giant magnetostrictive material （GMM） with a hole. The pretightening force of the CGMA is determined by testing. And the magnetic circuit analysis method is introduced to calculate magnetic field intensity of the actuator with a ball screw shaft. To suppress the thermal effects on the magnetostrictive outputs, an oil cooling method which can directly cool the heat source is adopted. A CGMA test platform is established and the static and dynamic output characteristics are respectively studied. The experimental results indicate that the CGMA has good linearity and no double-frequency effect under the bias magnetic field and the output accuracy of the CGMA is significantly improved with cooling measures. Although the output decreased with screw shaft through the actuator, the performance of CGMA meets the design requirements for ball screw preload with output displacement more than 26 μm and force up to 6200 N. The development of a CGMA will provide a new approach for automatic adjustment of double-nut ball screw preload.
基金Supported by National Natural Science Foundation of China,No.U1713221.
文摘BACKGROUND In robot-assisted(RA)spine surgery,the relationship between the surgical outcome and the learning curve remains to be evaluated.AIM To analyze the learning curve of RA pedicle screw fixation(PSF)through fitting the operation time curve based on the cumulative summation method.METHODS RA PSFs that were initially completed by two surgeons at the Beijing Jishuitan Hospital from July 2016 to March 2019 were analyzed retrospectively.Based on the cumulative sum of the operation time,the learning curves of the two surgeons were drawn and fit to polynomial curves.The learning curve was divided into the early and late stages according to the shape of the fitted curve.The operation time and screw accuracy were compared between the stages.RESULTS The turning point of the learning curves from Surgeons A and B appeared in the 18th and 17th cases,respectively.The operation time[150(128,188)min vs 120(105,150)min,P=0.002]and the screw accuracy(87.50%vs 96.30%,P=0.026)of RA surgeries performed by Surgeon A were significantly improved after he completed 18 cases.In the case of Surgeon B,the operation time(177.35±28.18 min vs 150.00±34.64 min,P=0.024)was significantly reduced,and the screw accuracy(91.18%vs 96.15%,P=0.475)was slightly improved after the surgeon completed 17 RA surgeries.CONCLUSION After completing 17 to 18 cases of RA PSFs,surgeons can pass the learning phase of RA technology.The operation time is reduced afterward,and the screw accuracy shows a trend of improvement.
