Background： Pancreatectomies have been identified as procedures with an increased risk of readmission.In surgical patients, readmissions within 30 days of discharge are usually procedure-related. We sought to determi...Background： Pancreatectomies have been identified as procedures with an increased risk of readmission.In surgical patients, readmissions within 30 days of discharge are usually procedure-related. We sought to determine predictors of 30-day readmission following pancreatic resections in a large healthcare system.Methods： We retrospectively collected information from the records of 383 patients who underwent pancreaticresections from 2004–2013. To find the predictors of readmission in the 30 days after discharge,we performed a univariate screen of possible variables using the Fisher’s exact test for categorical variables and the Mann–Whitney U test for continuous variables. Multivariate analysis was used to determinethe independent factors.展开更多
BACKGROUND Elective cholecystectomy(CCY)is recommended for patients with gallstone-related acute cholangitis(AC)following endoscopic decompression to prevent recurrent biliary events.However,the optimal timing and imp...BACKGROUND Elective cholecystectomy(CCY)is recommended for patients with gallstone-related acute cholangitis(AC)following endoscopic decompression to prevent recurrent biliary events.However,the optimal timing and implications of CCY remain unclear.AIM To examine the impact of same-admission CCY compared to interval CCY on patients with gallstone-related AC using the National Readmission Database(NRD).METHODS We queried the NRD to identify all gallstone-related AC hospitalizations in adult patients with and without the same admission CCY between 2016 and 2020.Our primary outcome was all-cause 30-d readmission rates,and secondary outcomes included in-hospital mortality,length of stay(LOS),and hospitalization cost.RESULTS Among the 124964 gallstone-related AC hospitalizations,only 14.67%underwent the same admission CCY.The all-cause 30-d readmissions in the same admission CCY group were almost half that of the non-CCY group(5.56%vs 11.50%).Patients in the same admission CCY group had a longer mean LOS and higher hospitalization costs attrib-utable to surgery.Although the most common reason for readmission was sepsis in both groups,the second most common reason was AC in the interval CCY group.CONCLUSION Our study suggests that patients with gallstone-related AC who do not undergo the same admission CCY have twice the risk of readmission compared to those who undergo CCY during the same admission.These readmis-sions can potentially be prevented by performing same-admission CCY in appropriate patients,which may reduce subsequent hospitalization costs secondary to readmissions.展开更多
Objective:Unplanned 30-day readmissions result in increased costs and decreased patient satisfaction.The objective of this study was to compare readmission rates before and after a multidisciplinary quality improvemen...Objective:Unplanned 30-day readmissions result in increased costs and decreased patient satisfaction.The objective of this study was to compare readmission rates before and after a multidisciplinary quality improvement initiative that focused on patient and staff education,use of targeted skilled nursing facilities,and appropriate use of patient observation status.Methods:This was a quality improvement study of all unplanned admissions to the Head and Neck Oncology service at a tertiary care facility during a 3-year period between October 2015 and September 2018.In October 2016,the Head and Neck Oncology service revised its discharge practices for patients undergoing extirpative and/or reconstructive surgery.These changes included enhancing patient education,increasing the use of a skilled nursing facility with directed staff education and patient handoffs by advanced practice nurses,and appropriate utilization of 23-h observation status for returning patients.The readmission rate from the pre-intervention era(October 2015 through September 2016)was compared to the readmission rate from the post-intervention era(October 2016 through September 2018).Secondary outcomes were the rates of 23-h observation within 30 days of the discharge as well as emergency room visits within 30 days of discharge.Results:In this sample of 449 patients,161(35.9%)were observed before the change-in-practice(before October 2016),and 288(64.1%)were observed following the change-in-practice(after September 2016).On univariable analysis,the risk of readmission declined by approximately 41.4%from the pre-intervention era,though this conclusion was not statistically significant(P=0.06).On multivariable analysis,patients at moderate or high risk of death were 2.31 times more likely than those at minor risk of death to readmit within 30 days(P=0.03).Similarly,those with recurrent or persistent cancer were 3.33 times more likely than those undergoing initial curative surgical management of cancer to readmit within 30 days(P=0.001).No patient characteristics were associated with a 23-h observation following discharge(allP>0.05).Conclusions were similar for emergency room visits following discharge.Conclusions:A three-part quality improvement strategy resulted in a clinically important decrease in 30-day readmissions,though the decline was not statistically significant.There were no significant changes in 23-h observation within 30 days of discharge or emergency room visits within 30 days of discharge.展开更多
This study focuses on the characteristics of the 30 60-day oscillation (MJO) associated with the interannual variability of the thermal state in the western Pacific warm pool. The composite results show that, the ampl...This study focuses on the characteristics of the 30 60-day oscillation (MJO) associated with the interannual variability of the thermal state in the western Pacific warm pool. The composite results show that, the amplitude of MJO convection over the tropical western Pacific tends to intensify (reduce) in the WARM (COLD) case. The negative correlations between MJO convection in the WARM and in the COLD cases are examined to be significant over most of the Asian-Pacific region. The evolutions of MJO convection and lower circulation, on the one hand, exhibit larger differences between the WARM and COLD cases, but on the other hand, display a unique feature in that a well-developed MJO cyclone (anticyclone) is anchored over the Asian-Western Pacific domain at the peak enhanced (suppressed) MJO convection phase over the western Pacific warm pool, either in the WARM or in the COLD case. This unique feature of MJO shows a Gill-type response of lower circulation to the convection and is inferred to be an inherent appearance of MJO. The context in the paper suggests there may exist interactions between MJO and the interannual variability of the thermal state in the western Pacific warm pool.展开更多
In this paper, the nonlinear Kelvin wave equations with 'positive-only' nonlinear (conditional) heating at the equator are reduced to a sixth-order nonlinear ordinary differential equation by using the Galerki...In this paper, the nonlinear Kelvin wave equations with 'positive-only' nonlinear (conditional) heating at the equator are reduced to a sixth-order nonlinear ordinary differential equation by using the Galerkin spectral truncated method. The stability analysis indicates that when the heating parameter increases, the supercritical pitchfork and Hopf bifurcations can occur for the prescribed three heating profiles. Numerical calculations are made with the help of the fourth-order Rung-Kutta method. It is found that the convection heating-related Hopf bifurcation can lead to limit cycle and chaotic solutions. In a wide range of heating parameter, the solutions possess 30-60-day periods, and are dominated by wavenumbers one and two, especially by wavenumber-one. In addition, the zonal winds of the low-frequency solutions have a phase reversal between the upper and lower tropospheres. Thus, it appears that the convection heating-related Hopf bifurcation might be a possible mechanism of 30-60-day oscillation in the tropical atmosphere.展开更多
This study investigates the structure and propagation of intraseasonal sea surface temperature（SST） variability in the South China Sea（SCS） on the 30-60-day timescale during boreal summer（May-September）. TRMM-ba...This study investigates the structure and propagation of intraseasonal sea surface temperature（SST） variability in the South China Sea（SCS） on the 30-60-day timescale during boreal summer（May-September）. TRMM-based SST, GODAS oceanic reanalysis and ERA-Interim atmospheric reanalysis datasets from 1998 to 2013 are used to examine quantitatively the atmospheric thermodynamic and oceanic dynamic mechanisms responsible for its formation. Power spectra show that the 30-60-day SST variability is predominant, accounting for 60% of the variance of the 10-90-day variability over most of the SCS. Composite analyses demonstrate that the 30-60-day SST variability is characterized by the alternate occurrence of basin-wide positive and negative SST anomalies in the SCS, with positive（negative） SST anomalies accompanied by anomalous northeasterlies（southwesterlies）. The transition and expansion of SST anomalies are driven by the monsoonal trough-ridge seesaw pattern that migrates northward from the equator to the northern SCS. Quantitative diagnosis of the composite mixed-layer heat budgets shows that, within a strong 30-60-day cycle, the atmospheric thermal forcing is indeed a dominant factor, with the mixed-layer net heat flux（MNHF） contributing around 60% of the total SST tendency, while vertical entrainment contributes more than 30%. However, the entrainment-induced SST tendency is sometimes as large as the MNHF-induced component, implying that ocean processes are sometimes as important as surface fluxes in generating the30-60-day SST variability in the SCS.展开更多
Introduction:Acute type A aortic dissection(ATAAD)is a catastrophic disease with fatal outcomes.Malperfusion syndrome(MPS)is a serious complication of ATAAD,with an incidence of 20–40%.Many studies have shown that MP...Introduction:Acute type A aortic dissection(ATAAD)is a catastrophic disease with fatal outcomes.Malperfusion syndrome(MPS)is a serious complication of ATAAD,with an incidence of 20–40%.Many studies have shown that MPS is the main risk factor for poor ATAAD prognosis.However,a risk scoring system for ATAAD based on MPS is lacking.Here,we designed a risk scoring system for ATAAD to assess mortality through quantitative assessment of relevant organ malperfusion and subsequently develop rational treatment strategies.Methods and analysis:This was a prospective observational study.Patients’perioperative clinical data were col-lected to establish a database of ATAAD(N≥3000)and determine whether these patients had malperfusion complica-tions.The Anzhen risk scoring system was established on the basis of organ malperfusion by using a random forest survival model and a logistics model.The better method was then chosen to establish a revised risk scoring system.Ethics and dissemination:This study received ethical approval from the Ethics Committees of Beijing Anzhen Hospital,Capital Medical University(KS2019034-1).Patient consent was waived because biological samples were not collected,and no patient rights were violated.Findings will be disseminated at scientific conferences and in peer-reviewed publications.展开更多
Based on the observational data in summer, the variations of intraseasonal oscillation (ISO) of the daily rainfall over the lower reaches of the Yangtze River valley (LYRV) were studied by using the non-integer spectr...Based on the observational data in summer, the variations of intraseasonal oscillation (ISO) of the daily rainfall over the lower reaches of the Yangtze River valley (LYRV) were studied by using the non-integer spectrum analysis. The NCEP/NCAR reanalysis data for the period of 1979―2005 were analyzed by principal oscillation pattern analysis (POP) to investigate the spatial and temporal characteristics of principal ISO patterns of the global circulation. The relationships of these ISO patterns to the rainfall ISO and the heavy precipitation process over LYRV were also discussed. It is found that the rainfall over LYRV in May―August is mainly of periodic oscillations of 10―20, 20―30 and 60―70 days, and the interannual variation of the intensity of its 20―30-day oscillation has a strongly positive correlation with the number of the heavy precipitation process. Two modes (POP1, POP2) are revealed by POP for the 20―30-day oscillation of the global 850 hPa geopotential height. One is a circumglobal telecon-nection wave train in the middle latitude of the Southern Hemisphere (SCGT) with an eastward propagation, and the other is the southward propagation pattern in the tropical western Pacific (TWP). The POP modes explain 7.72% and 7.66% of the variance, respectively. These two principal ISO patterns are closely linked to the low frequency rainfall and heavy precipitation process over LYRV, in which the probability for the heavy precipitation process over LYRV is 54.9% and 60.4% for the positive phase of the imaginary part of POP1 and real part of POP2, respectively. Furthermore, the models of the global atmospheric circulation for the 20―30-day oscillation in association with or without the heavy pre-cipitation process over LYRV during the Northern Hemisphere summer are set up by means of the composite analysis method. Most of the heavy precipitation processes over LYRV appear in Phase 4 of SCGT or Phase 6 of TWP. When the positive phases of 20―30-day oscillations for the rainfall over LYRV are associated with (without) the heavy precipitation process, a strong westerly stream appears (disappears) from the Arabian Sea via India and Bay of Bengal (BOB) to southern China and LYRV for the global 850 hPa filtered wind field during Phase 4 of SCGT. This situation is favorable (unfavorable) for the forming of the heavy precipitation process over LYRV. Similarly, a strong (weak) western wind belt forms from India through BOB to southern China and LYRV and the subtropical northwestern Pacific and central and eastern equatorial Pacific during Phase 6 of TWP for the cases with (without) the heavy precipitation process. The evolutions of these ISO patterns related to the 20―30-day oscillation are excited by either the interaction of extratropical circulation in both hemispheres or the heat source forcing in Asia monsoon domain and internal interaction of circulation in East Asia. These two global circulation models might therefore provide valuable information for the extended-range forecast of the heavy precipitation process over LYRV during the 10―30 days.展开更多
The 1999 East Asian summer monsoon was very unusual for its weak northward advance and remarkably anomalous climate conditions. The monsoonal southwesterly airflow and related rain belt in East Asia were blocked south...The 1999 East Asian summer monsoon was very unusual for its weak northward advance and remarkably anomalous climate conditions. The monsoonal southwesterly airflow and related rain belt in East Asia were blocked south of the Yangtze River Valley. The monsoonal airflow and major moisture transport conduct shifted eastward and turned northward to Japan from the tropical western Pacific rather than to East China from the South China Sea （SCS） as in normal years. Severe and prolonged drought occurred over extensive areas of North China and heavy precipitation in South China and Japan. The investigation on the possible intrinsic mechanisms related to such an anomalous monsoon year has shown that the unique behavior of intraseasonal oscillation may play an essential role during this process. During this year, the northward propagation of 30-60-day anomalous low-level cyclone/anticyclone collapsed in the region around 20°N and did not extend beyond the latitudes of the Yangtze River basin due to the barrier of strong cold air intrusion from the mid-latitudes. The southwesterly moisture flux on the northwestern flank of the anticyclonic moisture transport system in the western North Pacific, which was regulated by the northward shift of 30-60-day cyclonic/anticyclonic moisture transport, also did not reach the region north of 30°N as well. Under this circumstance, the weak northward advance of the monsoon westerlies and associated northward moisture transport could not arrive in North China and led to the severe droughts there in 1999. The SCS and South China were mostly affected by the airflow in the southern and northern flanks of the same 30-60-day cyclones or anticyclones, respectively, and thus controlled by the nearly reverse zonal wind and moisture convergent/divergent conditions. The rainfall in the SCS and South China showed out-of-phase oscillation through the transient local Hadley circulation, with the rainfall maximum occurring in the SCS （South China） when the 30-60-day anticyclone （cyclone） reached its peak phase.展开更多
AIM: To investigate risk factors for severe clostridium difficile associated diarrhoea (CDAD) in hospitalised patients. METHODS: We analysed risk factors for severe CDAD (associated with systemic signs of hypovolemia)...AIM: To investigate risk factors for severe clostridium difficile associated diarrhoea (CDAD) in hospitalised patients. METHODS: We analysed risk factors for severe CDAD (associated with systemic signs of hypovolemia) in 124 hospitalised patients by retrospective chart review. RESULTS: Severe CDAD was present in 27 patients (22%). Statistical analysis showed a significant association with a higher 30-d mortality (33% vs 4%, P < 0.001) and a higher proportion of longer hospital stay exceeding 14 d (74% vs 52%, P = 0.048). Charlson co-morbidity score (OR 1.29 for 1 point increment, P < 0.05) and serum C-reactive protein at diagnosis (OR 1.15 for 10 mg/L increment, P < 0.001) were independent predictors of severe CDAD. CONCLUSION: Patients with a severe level of co- morbidity and high serum C-reactive protein levels at the time of diagnosis should receive particular attention.展开更多
文摘Background： Pancreatectomies have been identified as procedures with an increased risk of readmission.In surgical patients, readmissions within 30 days of discharge are usually procedure-related. We sought to determine predictors of 30-day readmission following pancreatic resections in a large healthcare system.Methods： We retrospectively collected information from the records of 383 patients who underwent pancreaticresections from 2004–2013. To find the predictors of readmission in the 30 days after discharge,we performed a univariate screen of possible variables using the Fisher’s exact test for categorical variables and the Mann–Whitney U test for continuous variables. Multivariate analysis was used to determinethe independent factors.
文摘BACKGROUND Elective cholecystectomy(CCY)is recommended for patients with gallstone-related acute cholangitis(AC)following endoscopic decompression to prevent recurrent biliary events.However,the optimal timing and implications of CCY remain unclear.AIM To examine the impact of same-admission CCY compared to interval CCY on patients with gallstone-related AC using the National Readmission Database(NRD).METHODS We queried the NRD to identify all gallstone-related AC hospitalizations in adult patients with and without the same admission CCY between 2016 and 2020.Our primary outcome was all-cause 30-d readmission rates,and secondary outcomes included in-hospital mortality,length of stay(LOS),and hospitalization cost.RESULTS Among the 124964 gallstone-related AC hospitalizations,only 14.67%underwent the same admission CCY.The all-cause 30-d readmissions in the same admission CCY group were almost half that of the non-CCY group(5.56%vs 11.50%).Patients in the same admission CCY group had a longer mean LOS and higher hospitalization costs attrib-utable to surgery.Although the most common reason for readmission was sepsis in both groups,the second most common reason was AC in the interval CCY group.CONCLUSION Our study suggests that patients with gallstone-related AC who do not undergo the same admission CCY have twice the risk of readmission compared to those who undergo CCY during the same admission.These readmis-sions can potentially be prevented by performing same-admission CCY in appropriate patients,which may reduce subsequent hospitalization costs secondary to readmissions.
文摘Objective:Unplanned 30-day readmissions result in increased costs and decreased patient satisfaction.The objective of this study was to compare readmission rates before and after a multidisciplinary quality improvement initiative that focused on patient and staff education,use of targeted skilled nursing facilities,and appropriate use of patient observation status.Methods:This was a quality improvement study of all unplanned admissions to the Head and Neck Oncology service at a tertiary care facility during a 3-year period between October 2015 and September 2018.In October 2016,the Head and Neck Oncology service revised its discharge practices for patients undergoing extirpative and/or reconstructive surgery.These changes included enhancing patient education,increasing the use of a skilled nursing facility with directed staff education and patient handoffs by advanced practice nurses,and appropriate utilization of 23-h observation status for returning patients.The readmission rate from the pre-intervention era(October 2015 through September 2016)was compared to the readmission rate from the post-intervention era(October 2016 through September 2018).Secondary outcomes were the rates of 23-h observation within 30 days of the discharge as well as emergency room visits within 30 days of discharge.Results:In this sample of 449 patients,161(35.9%)were observed before the change-in-practice(before October 2016),and 288(64.1%)were observed following the change-in-practice(after September 2016).On univariable analysis,the risk of readmission declined by approximately 41.4%from the pre-intervention era,though this conclusion was not statistically significant(P=0.06).On multivariable analysis,patients at moderate or high risk of death were 2.31 times more likely than those at minor risk of death to readmit within 30 days(P=0.03).Similarly,those with recurrent or persistent cancer were 3.33 times more likely than those undergoing initial curative surgical management of cancer to readmit within 30 days(P=0.001).No patient characteristics were associated with a 23-h observation following discharge(allP>0.05).Conclusions were similar for emergency room visits following discharge.Conclusions:A three-part quality improvement strategy resulted in a clinically important decrease in 30-day readmissions,though the decline was not statistically significant.There were no significant changes in 23-h observation within 30 days of discharge or emergency room visits within 30 days of discharge.
基金supported by the National Natural Science Foundation of China under Grant No.40275013the National Key Programme for Developing Basic Sciences(G1998040900-part 1)LASG,Institute of Atmospheric Physics,Chinese Academy of Sciences.
文摘This study focuses on the characteristics of the 30 60-day oscillation (MJO) associated with the interannual variability of the thermal state in the western Pacific warm pool. The composite results show that, the amplitude of MJO convection over the tropical western Pacific tends to intensify (reduce) in the WARM (COLD) case. The negative correlations between MJO convection in the WARM and in the COLD cases are examined to be significant over most of the Asian-Pacific region. The evolutions of MJO convection and lower circulation, on the one hand, exhibit larger differences between the WARM and COLD cases, but on the other hand, display a unique feature in that a well-developed MJO cyclone (anticyclone) is anchored over the Asian-Western Pacific domain at the peak enhanced (suppressed) MJO convection phase over the western Pacific warm pool, either in the WARM or in the COLD case. This unique feature of MJO shows a Gill-type response of lower circulation to the convection and is inferred to be an inherent appearance of MJO. The context in the paper suggests there may exist interactions between MJO and the interannual variability of the thermal state in the western Pacific warm pool.
文摘In this paper, the nonlinear Kelvin wave equations with 'positive-only' nonlinear (conditional) heating at the equator are reduced to a sixth-order nonlinear ordinary differential equation by using the Galerkin spectral truncated method. The stability analysis indicates that when the heating parameter increases, the supercritical pitchfork and Hopf bifurcations can occur for the prescribed three heating profiles. Numerical calculations are made with the help of the fourth-order Rung-Kutta method. It is found that the convection heating-related Hopf bifurcation can lead to limit cycle and chaotic solutions. In a wide range of heating parameter, the solutions possess 30-60-day periods, and are dominated by wavenumbers one and two, especially by wavenumber-one. In addition, the zonal winds of the low-frequency solutions have a phase reversal between the upper and lower tropospheres. Thus, it appears that the convection heating-related Hopf bifurcation might be a possible mechanism of 30-60-day oscillation in the tropical atmosphere.
基金supported by the SOA Program on Global Change and Air–Sea Interactions (Grant No.GASI-IPOVAI03)the National Basic Research Program of China (Grant No.2014CB953902)+1 种基金the Natural Science Foundation of China (Grant Nos.91537103 and 41375087)the Priority Research Program of the Chinese Academy of Sciences (Grant Nos.QYZDY-SSWDQC018 and XDA11010402)
文摘This study investigates the structure and propagation of intraseasonal sea surface temperature（SST） variability in the South China Sea（SCS） on the 30-60-day timescale during boreal summer（May-September）. TRMM-based SST, GODAS oceanic reanalysis and ERA-Interim atmospheric reanalysis datasets from 1998 to 2013 are used to examine quantitatively the atmospheric thermodynamic and oceanic dynamic mechanisms responsible for its formation. Power spectra show that the 30-60-day SST variability is predominant, accounting for 60% of the variance of the 10-90-day variability over most of the SCS. Composite analyses demonstrate that the 30-60-day SST variability is characterized by the alternate occurrence of basin-wide positive and negative SST anomalies in the SCS, with positive（negative） SST anomalies accompanied by anomalous northeasterlies（southwesterlies）. The transition and expansion of SST anomalies are driven by the monsoonal trough-ridge seesaw pattern that migrates northward from the equator to the northern SCS. Quantitative diagnosis of the composite mixed-layer heat budgets shows that, within a strong 30-60-day cycle, the atmospheric thermal forcing is indeed a dominant factor, with the mixed-layer net heat flux（MNHF） contributing around 60% of the total SST tendency, while vertical entrainment contributes more than 30%. However, the entrainment-induced SST tendency is sometimes as large as the MNHF-induced component, implying that ocean processes are sometimes as important as surface fluxes in generating the30-60-day SST variability in the SCS.
基金supported by the Beijing Municipal Science and Technology Commission[No.Z191100006619093&Z191100006619094]the National Science Foundation of China(No.81970393).
文摘Introduction:Acute type A aortic dissection(ATAAD)is a catastrophic disease with fatal outcomes.Malperfusion syndrome(MPS)is a serious complication of ATAAD,with an incidence of 20–40%.Many studies have shown that MPS is the main risk factor for poor ATAAD prognosis.However,a risk scoring system for ATAAD based on MPS is lacking.Here,we designed a risk scoring system for ATAAD to assess mortality through quantitative assessment of relevant organ malperfusion and subsequently develop rational treatment strategies.Methods and analysis:This was a prospective observational study.Patients’perioperative clinical data were col-lected to establish a database of ATAAD(N≥3000)and determine whether these patients had malperfusion complica-tions.The Anzhen risk scoring system was established on the basis of organ malperfusion by using a random forest survival model and a logistics model.The better method was then chosen to establish a revised risk scoring system.Ethics and dissemination:This study received ethical approval from the Ethics Committees of Beijing Anzhen Hospital,Capital Medical University(KS2019034-1).Patient consent was waived because biological samples were not collected,and no patient rights were violated.Findings will be disseminated at scientific conferences and in peer-reviewed publications.
基金Supported by the Program for the Fundamental Research of China Meteorological Administration (Grant No. 200726)
文摘Based on the observational data in summer, the variations of intraseasonal oscillation (ISO) of the daily rainfall over the lower reaches of the Yangtze River valley (LYRV) were studied by using the non-integer spectrum analysis. The NCEP/NCAR reanalysis data for the period of 1979―2005 were analyzed by principal oscillation pattern analysis (POP) to investigate the spatial and temporal characteristics of principal ISO patterns of the global circulation. The relationships of these ISO patterns to the rainfall ISO and the heavy precipitation process over LYRV were also discussed. It is found that the rainfall over LYRV in May―August is mainly of periodic oscillations of 10―20, 20―30 and 60―70 days, and the interannual variation of the intensity of its 20―30-day oscillation has a strongly positive correlation with the number of the heavy precipitation process. Two modes (POP1, POP2) are revealed by POP for the 20―30-day oscillation of the global 850 hPa geopotential height. One is a circumglobal telecon-nection wave train in the middle latitude of the Southern Hemisphere (SCGT) with an eastward propagation, and the other is the southward propagation pattern in the tropical western Pacific (TWP). The POP modes explain 7.72% and 7.66% of the variance, respectively. These two principal ISO patterns are closely linked to the low frequency rainfall and heavy precipitation process over LYRV, in which the probability for the heavy precipitation process over LYRV is 54.9% and 60.4% for the positive phase of the imaginary part of POP1 and real part of POP2, respectively. Furthermore, the models of the global atmospheric circulation for the 20―30-day oscillation in association with or without the heavy pre-cipitation process over LYRV during the Northern Hemisphere summer are set up by means of the composite analysis method. Most of the heavy precipitation processes over LYRV appear in Phase 4 of SCGT or Phase 6 of TWP. When the positive phases of 20―30-day oscillations for the rainfall over LYRV are associated with (without) the heavy precipitation process, a strong westerly stream appears (disappears) from the Arabian Sea via India and Bay of Bengal (BOB) to southern China and LYRV for the global 850 hPa filtered wind field during Phase 4 of SCGT. This situation is favorable (unfavorable) for the forming of the heavy precipitation process over LYRV. Similarly, a strong (weak) western wind belt forms from India through BOB to southern China and LYRV and the subtropical northwestern Pacific and central and eastern equatorial Pacific during Phase 6 of TWP for the cases with (without) the heavy precipitation process. The evolutions of these ISO patterns related to the 20―30-day oscillation are excited by either the interaction of extratropical circulation in both hemispheres or the heat source forcing in Asia monsoon domain and internal interaction of circulation in East Asia. These two global circulation models might therefore provide valuable information for the extended-range forecast of the heavy precipitation process over LYRV during the 10―30 days.
基金Acknowledgements. The study is partially supported by National Natural Science Foundation of China （Grant No. 40605020） and 973 Program 2006CB403604.
文摘The 1999 East Asian summer monsoon was very unusual for its weak northward advance and remarkably anomalous climate conditions. The monsoonal southwesterly airflow and related rain belt in East Asia were blocked south of the Yangtze River Valley. The monsoonal airflow and major moisture transport conduct shifted eastward and turned northward to Japan from the tropical western Pacific rather than to East China from the South China Sea （SCS） as in normal years. Severe and prolonged drought occurred over extensive areas of North China and heavy precipitation in South China and Japan. The investigation on the possible intrinsic mechanisms related to such an anomalous monsoon year has shown that the unique behavior of intraseasonal oscillation may play an essential role during this process. During this year, the northward propagation of 30-60-day anomalous low-level cyclone/anticyclone collapsed in the region around 20°N and did not extend beyond the latitudes of the Yangtze River basin due to the barrier of strong cold air intrusion from the mid-latitudes. The southwesterly moisture flux on the northwestern flank of the anticyclonic moisture transport system in the western North Pacific, which was regulated by the northward shift of 30-60-day cyclonic/anticyclonic moisture transport, also did not reach the region north of 30°N as well. Under this circumstance, the weak northward advance of the monsoon westerlies and associated northward moisture transport could not arrive in North China and led to the severe droughts there in 1999. The SCS and South China were mostly affected by the airflow in the southern and northern flanks of the same 30-60-day cyclones or anticyclones, respectively, and thus controlled by the nearly reverse zonal wind and moisture convergent/divergent conditions. The rainfall in the SCS and South China showed out-of-phase oscillation through the transient local Hadley circulation, with the rainfall maximum occurring in the SCS （South China） when the 30-60-day anticyclone （cyclone） reached its peak phase.
文摘AIM: To investigate risk factors for severe clostridium difficile associated diarrhoea (CDAD) in hospitalised patients. METHODS: We analysed risk factors for severe CDAD (associated with systemic signs of hypovolemia) in 124 hospitalised patients by retrospective chart review. RESULTS: Severe CDAD was present in 27 patients (22%). Statistical analysis showed a significant association with a higher 30-d mortality (33% vs 4%, P < 0.001) and a higher proportion of longer hospital stay exceeding 14 d (74% vs 52%, P = 0.048). Charlson co-morbidity score (OR 1.29 for 1 point increment, P < 0.05) and serum C-reactive protein at diagnosis (OR 1.15 for 10 mg/L increment, P < 0.001) were independent predictors of severe CDAD. CONCLUSION: Patients with a severe level of co- morbidity and high serum C-reactive protein levels at the time of diagnosis should receive particular attention.
