The residence-time distribution (RTD) and the compartment model were applied to characterizing the flow regions in red mud separation thickener’s feedwells. Combined with the experimental work, validated mathematic...The residence-time distribution (RTD) and the compartment model were applied to characterizing the flow regions in red mud separation thickener’s feedwells. Combined with the experimental work, validated mathematical model as well as three-dimensional computational fluid dynamics (CFD) model was established to analyze the flow regions of feedwells on an industrial scale. The concept of RTD, although a well-known method for the characterization of mixing behavior in conventional mixers and reactors, is still a novel measure for the characterization of mixing in feedwells. Numerical simulation results show that the inlet feed rate and the aspect ratio of feedwells are the most critical parameters which affect the RTD of feedwell. Further simulation experiments were then carried out. Under the optimal operation conditions, the volume fraction of dead zone can reduce by10.8% and an increasement of mixing flow volume fraction by 6.5% is also observed. There is an optimum feed inlet rate depending on the feedwell design. The CFD model in conjunction with the RTD analysis then can be used as an effective tool in the design, evaluation and optimization of thickener feedwell in the red mud separation.展开更多
A time-frequency signal processing method for two-phase flow through a horizontal Venturi based on adaptive optimal-kernel (AOK) was presented in this paper.First,the collected dynamic differential pressure signal o...A time-frequency signal processing method for two-phase flow through a horizontal Venturi based on adaptive optimal-kernel (AOK) was presented in this paper.First,the collected dynamic differential pressure signal of gas-liquid two-phase flow was preprocessed,and then the AOK theory was used to analyze the dynamic differ-ential pressure signal.The mechanism of two-phase flow was discussed through the time-frequency spectrum.On the condition of steady water flow rate,with the increasing of gas flow rate,the flow pattern changes from bubbly flow to slug flow,then to plug flow,meanwhile,the energy distribution of signal fluctuations show significant change that energy transfer from 15-35 Hz band to 0-8 Hz band;moreover,when the flow pattern is slug flow,there are two wave peaks showed in the time-frequency spectrum.Finally,a number of characteristic variables were defined by using the time-frequency spectrum and the ridge of AOK.When the characteristic variables were visu-ally analyzed,the relationship between different combination of characteristic variables and flow patterns would be gotten.The results show that,this method can explain the law of flow in different flow patterns.And characteristic variables,defined by this method,can get a clear description of the flow information.This method provides a new way for the flow pattern identification,and the percentage of correct prediction is up to 91.11%.展开更多
Objective To evaluate the efficacy of minimally invasive perventricular device closure of ventricular septal defect(VSD). Methods Between September 2011 and February 2013, we collected 40 patients who underwent perven...Objective To evaluate the efficacy of minimally invasive perventricular device closure of ventricular septal defect(VSD). Methods Between September 2011 and February 2013, we collected 40 patients who underwent perventricular closure via a small lower sternal incision(minimally invasive group), aged 15.5±3.5 years(12 months to 32 years) with a body weight of 24.2±7.5 kg(10.8-58.0 kg). The mean size of VSD was 5.6±0.5 mm(2-14 mm). Another 40 patients were included as the surgical group, receiving the conventional surgical repair of VSD. The device of the minimally invasive group was released under the guidance of transesophageal echocardiography. Success rate, cardiac indicators, and clinical outcomes of the 2 groups were compared. Results The patients in the surgical group and those in the minimally invasive group showed similar results in success rate(both 97.5%). The procedure time, intensive care unit stay, hospital stay, and postoperative recovery time in the minimally invasive group were significantly shorter than those in the surgical group(58±21 minutes versus 145±26 minutes, 2±1 days versus 8±3 days, 5±1 days versus 16±6 days, 3±1 days versus 90±20 days, all P<0.05). The minimally invasive group had a higher incidence of conduction anomalies(17.5% versus 2.5%, P<0.05). In the follow-up period of 3-12 months, there was no new residual shunt, noticeable aortic regurgitation, significant arrhythmias, or device failure except for new complications in the surgical group. Conclusions The success rate of minimally invasive perventricular device closure of VSD under transesophageal echocardiography guidance is similar to that of conventional surgical repair, but the short-term outcomes of the minimally invasive approach is much better. Long-term follow-up is necessary to confirm the effectiveness of this technique.展开更多
Objective Doppler derived mitral peak early diastolic filling velocity to deceleration time ratio (E/DT) has been proposed as parameter for predicting prognosis in general population. This study prospectively invest...Objective Doppler derived mitral peak early diastolic filling velocity to deceleration time ratio (E/DT) has been proposed as parameter for predicting prognosis in general population. This study prospectively investigates the incremental prognostic value of E/DT over clinical, conven- tional eehocardiographic and mitral-Doppler variables in patients hospitalized for decompensated heart failure (HF). Methods We analyzed 95 HF patients (mean age 64.8 ± 12.2 years) hospitalized at our institution from January 2010 to March 2012. The primary end-point was cardiac death or hospitalization, whichever occurred first. Cox regression analysis was performed to identify significant predictors of outcomes. Results During follow-up (median 37.7 months) 13 patients died and 44 were hospitalized for a cardiac event. At univariable analysis, New York Heart Association (NYHA) functional class, furosemide dosage, lateral tricuspidal annular plane systolic excursion, deceleration lime and E/DT were predictive of outcome. At multivariable analysis, E/DT was the only predictor of prognosis (hazard ratio = 1.02, P = 0.018), giving incremental prognostic information to clinical and other echocardio-graphic measures (global chi-square from 15.4 to 25.2; P = 0.032). Conclusions FJDT gives independent and incremental prognostic information in HF patients.展开更多
Objective To evaluate left univentricular (LUV) pacing for cardiac resynchronization therapy (CRT) using a rate-adaptive atrioven- tricular delay (RAAVD) algorithm to track physiological atrioventricular delay ...Objective To evaluate left univentricular (LUV) pacing for cardiac resynchronization therapy (CRT) using a rate-adaptive atrioven- tricular delay (RAAVD) algorithm to track physiological atrioventricular delay (AVD). Methods A total of 72 patients with congestive heart failure (CHF) were randomized to RAAVD LUV pacing versus standard biventricular (BiV) pacing in a 1 : 1 ratio. Echocardiography was used to optimize AVD for both groups. The effects of sequential BiV pacing and LUV pacing with optimized A-V (right atrio-LV) delay using an RAAVD algorithm were compared. The standard deviation (SD) of the S/R ratio in lead VI at five heart rate (HR) segments (Rs/R-SD5), defined as the "tracking index," was used to evaluate the accuracy of the RAAVD algorithm for tracking physiological AVD. Results TheQRS complex duration (132 ± 9.8 vs. 138± 10ms, P 〈 0.05), the time required for optimization (21 ±5 vs. 50±8min, P〈 0.001), the mitral regurgitant area (1.9 ± 1.1 vs. 2.5 ± 1.3 em2, P 〈 0.05), the interventricular mechanical delay time (60.7 ± 13.3 ms vs. 68.3 ± 14.2 ms, P 〈 0.05), and the average annual cost (13,200 ± 1000 vs. 21,600 ± 2000 RMB, P 〈 0.001) in the RAAVD LUV pacing group were significantly less than those in the standard BiV pacing group. The aortic valve velocity-time integral in the RAAVD LUV pacing group was greater than that in the standard BiV pacing group (22.7 ± 2.2 vs. 21.4 ± 2.1 cm, P 〈 0.05). The Rs/R-SD5 was 4.08 ± 1.91 in the RAAVD LUV pacing group, and was significantly negatively correlated with improved left ventricular ejection fraction (LVEF) (ALVEF, Pearson's r = -0.427, P = 0.009), and positively correlated with New York Heart Association class (Spearman's r - 0.348, P 0.037). Conclusions RAAVD LUV pacing is as effective as standard BiV pacing, can be more physiological than standard BiV pacing, and can de- crease the average annual cost of CRT.展开更多
AIM To describe the prevalence of posttransplant metabolic syndrome(PTMS) after donation after cardiac death(DCD) liver transplantation(LT) and the pre-and postoperative risk factors.METHODS One hundred and forty-seve...AIM To describe the prevalence of posttransplant metabolic syndrome(PTMS) after donation after cardiac death(DCD) liver transplantation(LT) and the pre-and postoperative risk factors.METHODS One hundred and forty-seven subjects who underwent DCD LT from January 2012 to February 2016 were enrolled in this study. The demographics and the clinical characteristics of pre-and post-transplantation were collected for both recipients and donors. PTMS was defined according to the 2004 Adult Treatment Panel-Ⅲ criteria. All subjects were followed monthly for the initial 6 mo after discharge, and then, every 3 mo for 2 years. The subjects were followed every 6 mo or as required after 2 years post-LT.RESULTS The prevalence of PTMS after DCD donor orthotopic LT was 20/147(13.6%). Recipient's body mass index(P = 0.024), warm ischemia time(WIT)(P = 0.045), and posttransplant hyperuricemia(P = 0.001) were significantly associated with PTMS. The change in serum uric acid levels in PTMS patients was significantly higher than that in non-PTMS patients(P < 0.001). After the 1 s t mo, the level of serum uric acid of PTMS patients rose continually over a period, while it was unaltered in non-PTMS patients. After transplantation, the level of serum uric acid in PTMS patients was not associated with renal function.CONCLUSION PTMS could occur at early stage after DCD LT with growing morbidity with the passage of time. WIT and post-LT hyperuricemia are associated with the prevalence of PTMS. An increased serum uric acid level is highly associated with PTMS and could act as a serum marker in this disease.展开更多
Background Although previous studies using Korean data have already reported higher rates of mortality in women, it is less clear whether these gender differences in prognosis post ST-segment elevation myocardial infa...Background Although previous studies using Korean data have already reported higher rates of mortality in women, it is less clear whether these gender differences in prognosis post ST-segment elevation myocardial infarction (STEMI), are age dependent. The aim of this study is to examine the gender-age interaction with early and late mortality in patients with STEMI enrolled in the Korean nationwide regis-try. Methods This prospective study stratified outcomes according to gender and age from 17,021 STEMI patients. We compared in-hospital, early (30 days) and late (12 months) mortality between gender to examine the gender-age interaction in multivariable models. Results In younger women (〈 60 years), in-hospital [5.8% vs. 2.5%, P 〈 0.001; unadjusted odds ratios (OR): 2.41, 95% confidence inter-vals (CI): 1.59-3.66], early (6.2% vs. 2.6%, P 〈 0.001; unadjusted OR: 2.4, 95% CI: 2.12-2.72) and late mortality (7.0% vs. 3.1%, P 〉 0.001; unadjusted OR: 2.33, 95% CI: 2.08-2.61) were significantly higher compared with men. However, after adjustment for patient characteristics, Killip class ≥ 3, symptom to balloon time and major bleeding, and in-hospital bleeding, overall early and late mortality were no longer re-lated to gender in any age groups. Conclusions Among a Korean population with STEMI, higher early and late mortality in younger women may be explained by poor patient characteristics, higher Killip class ≥3, longer symptom to balloon time and more frequent major bleeding. Therefore, based on gender-age differences, more precise and aggressive preventive strategies focused on risk factor reduction, education and more intensive management for yotmger women should be performed.展开更多
Time has multiple aspects and is difficult to define as one unique entity, which therefore led to multiple interpretations in physics and philosophy. However, if the perception of time is considered as a composite tim...Time has multiple aspects and is difficult to define as one unique entity, which therefore led to multiple interpretations in physics and philosophy. However, if the perception of time is considered as a composite time concept, it can be decomposed into basic invariable components for the perception of progressive and support-fixed time and into secondary components with possible association to unit-defined time or tense. Progressive time corresponds to Bergson's definition of duration without boundaries, which cannot be divided for measurements. Time periods are already lying in the past and fixed on different kinds of support. The human memory is the first automatic support, but any other support suitable for time registration can also be considered. The true reproduction of original time from any support requires conditions identical to the initial conditions, if not time reproduction becomes artificially modified as can be seen with a film. Time reproduction can be artificially accelerated, slowed down, extended or diminished, and also inverted from the present to the past, which only depends on the manipulation of the support, to which time is firmly linked. Tense associated to progressive and support fixed time is a psychological property directly dependent on an observer, who judges his present as immediate, his past as finished and his future as uncertain. Events can be secondarily associated to the tenses of an observer. Unit-defined time is essential for physics and normal live and is obtained by comparison of support-fixed time to systems with regular motions, like clocks. The association of time perception to time units can also be broken. Einstein's time units became relative, in quantum mechanics, some physicist eliminated time units, others maintained them. Nevertheless, even the complete elimination of time units is not identical to timelessness, since the psychological perception of progressive and support-fixed time still remains and cannot be ignored. It is not seizable by physical methods, but experienced by everybody in everyday life. Contemporary physics can only abandon the association of time units or tenses to the basic components in perceived time.展开更多
Objectives: To probe some more important factors affecting the HIV epidemic by surveying the relationshipbetween AIDS high risk behaviors and childhood status,attitude/perception to gender of male/sex orientation andr...Objectives: To probe some more important factors affecting the HIV epidemic by surveying the relationshipbetween AIDS high risk behaviors and childhood status,attitude/perception to gender of male/sex orientation andrare experiences/Psy-chology among Chinese gays. Methods: Data were collected from 240 Chinese gays whowere attracted by their same gender. Results: The extent of sex among China's Mainland gays issimilar to that of industrialized countries, and behaviorsthat exacerbate the HIV epidemic are universal.Perceptions 'being a girl is better',' Dislike toys likeswords or pistols in early childhood were predictors topassive anal intercourse in adulthood. Those gay men whobegan sexual intercourse younger than 16 years old tendedto have more sex partners and suffered more pain. Thosedisliked gender of male or self-regarded as female tended tohave more passive anal intercourse and related to childhoodcross-gender experience/psychology while those were raised as girls by their parentsdid not take on e above characters. Individuals who experienced sex coercion and drug abuse were the twosubgroups with the greatest high-risk behaviors. Individualswho had sex with females had the greatest number of malesex partners and were more prone to group sex. Individualswith pedophilia or gerontophilia had more casual sexpartners. Psychological problems encountered by Chinese Conclusions: The prospect of an extensive AIDSepidemic among Chinese gays does exist and somesubgroups of gays play more important roles in theepidemic. Some high risk behaviors among adult gays canbe foreseen explicitly by the predictors taking on inchildhood, and closely relate to attitude/perception, togender of male, to some rare experience/psychology.展开更多
AIM:To evaluate the diagnosis of chest pain with foregut symptoms in Chinese patients. METHODS:Esophageal manometric studies, 24-h introesophageal pH monitoring and 24-h electrocardiograms(Holter electrocardiography)w...AIM:To evaluate the diagnosis of chest pain with foregut symptoms in Chinese patients. METHODS:Esophageal manometric studies, 24-h introesophageal pH monitoring and 24-h electrocardiograms(Holter electrocardiography)were performed in 61 patients with chest pain. RESULTS:Thirty-nine patients were diagnosed with non-specific esophageal motility disorders(29 patients with abnormal gastroesophageal reflux and eight patients with myocardial ischemia).Five patients had diffuse spasm of the esophagus plus abnormal gastroesophageal reflux(two patients had concomitant myocardial ischemia),and one patient was diagnosed with nutcracker esophagus. CONCLUSION:The esophageal manometric studies, 24-h intra-esophageal pH monitoring and Holter electrocardiography are significant for the differential diagnosis of chest pain,particularly in patients with foregut symptoms.In cases of esophageal motility disorders,pathological gastroesophageal reflux may be a major cause of chest pain with non-specific esophageal motility disorders.Spasm of the esophageal smooth muscle might affect the heart-coronary smooth muscle,leading to myocardial ischemia.展开更多
The high order compact d if ference method is developed for solving the perturbation equations based on Navi er Stokes equations, and is used in studying complex evolution processes from w all negative pulse to the ...The high order compact d if ference method is developed for solving the perturbation equations based on Navi er Stokes equations, and is used in studying complex evolution processes from w all negative pulse to the turbulent coherent structure in the channel flow. Th is method contains three dimensional coupling difference scheme with high accur acy and high resolution, and the high order time splitting methods. Compared with the general spectral method, the method can be used to research turbule nt coherent structure under more general boundary conditions and in flow domains . In this paper, the generation and evolution of the turbulent coherent structur es ind uced by wall pulse in the channel flow are simulated, and the basic characterist ics and rules of the turbulent coherent structure are shown. Computational r esults indicate that a wall negative pulse is more convenient than the resonant three wave model.展开更多
To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part...To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.展开更多
AIM:To evaluate pretreatment serum carcinoembryonic antigen(CEA) as a predictor of survival for patients with locally advanced gastric cancer receiving perioperative chemotherapy.METHODS:We retrospectively studied a c...AIM:To evaluate pretreatment serum carcinoembryonic antigen(CEA) as a predictor of survival for patients with locally advanced gastric cancer receiving perioperative chemotherapy.METHODS:We retrospectively studied a cohort of 228 gastric cancer patients who underwent D2 gastrectomy combined with chemotherapy at the Sun Yat-sen University Cancer Center between January 2005 and December 2009.Among them,168 patients received 6-12 cycles of oxaliplatin-based adjuvant(post-operative) chemotherapy,while 60 received perioperative chemotherapy(2 cycles of FOLFOX6 or XELOX before surgery and 4-10 cycles after surgery).Serum CEA was measured using an enzyme immunoassay.The followup lasted until December 2010.RESULTS:In the group that had elevated serum CEA,the difference in survival time between patients receiving perioperative chemotherapy and those receiving adjuvant chemotherapy had no statistical significance(P > 0.05).However,in the group that had normal serum CEA,patients receiving perioperative chemotherapy had a longer survival time.In multivariate analysis,T staging and lymph node metastatic rate were independent prognostic factors for the patients.Perioperative chemotherapy improved the overall survival of patients who had a normal pretreatment CEA level(P = 0.070).CONCLUSION:Normal pretreatment serum CEA is a predictor of survival for patients receiving perioperative chemotherapy.展开更多
To test the accuracy of real-time three-dimensional echocardiography (RT3DE) imaging system for evaluating left ventricular mass (LVM) in phantom and excised canine heart. Methods Ten left ventricular (LV) wall phanto...To test the accuracy of real-time three-dimensional echocardiography (RT3DE) imaging system for evaluating left ventricular mass (LVM) in phantom and excised canine heart. Methods Ten left ventricular (LV) wall phantoms made of two rubber-bursas, ten excised canine hearts underwent RT3DE and two-dimensional echocardiography (2DE). In RT3DE "full volume" imaging, the myocardial volume was mea-sured using 2,4,8, and 16-plane method with the analysis software of RT3DE. Mass was then calculated by multiplying the resulting myocardial volume by specific density of myocardial tissue. In 2DE the masses were measured by area-length meth-od. The true LV wall phantom mass was measured by water displacement and the canine LVM was weighed by anatomy, which served as a reference standard. We compared RT3DE or 2DE with true mass. Results In LV wall phantoms, RT3DE correlated with true masses strongly (r = 0.813-0.994) and weakly correlated between 2DE and true masses (r = 0.628). In excised canine hearts, there is an excellent correlation between RT3DE and true masses (r = 0.764-0.991), while 2DE value showed a lesser correlation (r = 0.514). There are no difference between RT-3DE and true masses (P > 0.05) but different between 2DE and true masses (P < 0.05). In different planes, there was no difference between 8-plane and 16-plane (P > 0.05) but different between 8-plane and 2, 4-plane (P < 0.05). Conclusion RT3DE can accurately quantify LVM and provide a new tool to evaluate LV function. For LVM by RT3DE, 8-plane measurement method is the best choice for accuracy and convenience.展开更多
The signals and the neuronal mechanisms that underlying the behavior, actions, and action-directed goals in man and animals during conscious state are not fully understood, and the neuro-dynamic mechanisms and the sou...The signals and the neuronal mechanisms that underlying the behavior, actions, and action-directed goals in man and animals during conscious state are not fully understood, and the neuro-dynamic mechanisms and the source of these neuronal signals are not authenticated. Temporal judgment alone can neither account for neural signaling necessary for emergence of conscious act nor explain RP (Readiness Potential, the accepted neural correlate time needed for the neurons to fire) that precedes the onset of action or the latency time of 0.5 ms that precedes the conscious act found by Libet. Neuronal feedback mechanisms between the heart and the brain seem feasible and logical suggestions to be considered, so clearly, I would suggest that the onset of a conscious-directed goal, conscious action, freewill, intension, and the neural signals and mechanisms that control them may depend upon the interaction between two sources: (1) the brain and (2) the heart. The temporal-cardiac (neural system) interaction has been well established in heart-brain interaction studies by many workers who found that the work of the heart precedes that of the brain in EEG (electroencephalography) findings in conscious stimulation, which may explain and account for RP time and the 0.5 ms latency period of Libet's important findings. According to my hypothesis (AlFaki 2009) and views, the temporal neurons in the soma to-sensory cortex will respond to conscious stimulation only after receiving neuronal signals from the cardiac neurons in the neural plexus of the heart; after variable millisecond equivalent to RP or Libet's latency period prior to temporal neuronal firinging in response to conscious act, this time is the time needed by cardiac neurons to process and signal information to the brain through feedback mechanism and heart-brain interaction.展开更多
Background Studies have shown that staged percutaneous coronary intervention (PCI) for non-culprit lesions is beneficial for prog- nosis of ST-segment elevation myocardial infarction (STEMI) patients with multives...Background Studies have shown that staged percutaneous coronary intervention (PCI) for non-culprit lesions is beneficial for prog- nosis of ST-segment elevation myocardial infarction (STEMI) patients with multivessel disease. However, the optimal timing of staged re- vascularization is still controversial. This study aimed to find the optimal timing of staged revascularization. Methods A total of 428 STEMI patients with multivessel disease who underwent primary PCI and staged PCI were included. According to the time interval between primary and staged PCI, patients were divided into three groups (〈 1 week, 1- weeks, and 2-12 weeks after primary PCI). The primary endpoint was major adverse cardiovascular events (MACE), a composite of all-cause death, non-fatal re-infarction, repeat revascularization, and stroke. Cox regression model was used to assess the association between staged PCI timing and risk of MACE. Results During the follow-up, 119 participants had MACEs. There was statistical difference in MACE incidence among the three groups (〈 1 week: 23.0%; 1-2 weeks: 33.0%; 2-12 weeks: 40.0%; P = 0.001). In the multivariable adjustment model, the timing interval of staged PCI ≤ 1 week and l-2 weeks were both significantly associated with a lower risk of MACE [hazard ratio (HR): 0.40, 95% confidence intervals (CI): 0.24-4).65; HR: 0.54, 95% CI: 0.3 lq3.93, respectively], mainly attributed to a lower risk of repeat revascularization (HR: 0.41, 95% CI: 0.24-0.70; HR: 0.36, 95% CI: 0.18-0.7), compared with a strategy of 2-12 weeks later of primary PCI. Conclusions The optimal timing of staged PCI for non-culprit vessels should be within two weeks after primary PCI for STEMI patients.展开更多
Winter North Atlantic Oscillation(NAO)indexes from observations based on various winter durations are compared.Results show that there are significant differences in the interannual and decadal variations of these NAO...Winter North Atlantic Oscillation(NAO)indexes from observations based on various winter durations are compared.Results show that there are significant differences in the interannual and decadal variations of these NAO indexes.For the same data source,a different definition of winter duration can lead to different signs of NAO index in some years,which mainly appear to be in the period of decadal phase transition.The different winter durations induce different cycles of the observation-based NAO.The longer the winter duration,the stronger the decadal variation.The NAO defined by different winter durations also can generate different descriptions of the NAO action centers,including the position and movement.The longer the winter duration,the more southerly action centers appear to be.The movement of the action centers affects not only site-based NAO indexes but also those defined by other methods,such as empirical orthogonal function(EOF)analysis.The length of time used in EOF analysis has a great influence on the spatial pattern of the NAO mode,which results in a considerable difference between the corresponding NAO indexes.Regardless of which NAO index is used,the NAO-related SST anomalies show the same tripole pattern.The longer the winter duration,the more significant the relationship between the NAO and SST affected by the timescale of sea-air interaction.展开更多
基金Project (50876116) supported by the National Natural Science Foundation of China
文摘The residence-time distribution (RTD) and the compartment model were applied to characterizing the flow regions in red mud separation thickener’s feedwells. Combined with the experimental work, validated mathematical model as well as three-dimensional computational fluid dynamics (CFD) model was established to analyze the flow regions of feedwells on an industrial scale. The concept of RTD, although a well-known method for the characterization of mixing behavior in conventional mixers and reactors, is still a novel measure for the characterization of mixing in feedwells. Numerical simulation results show that the inlet feed rate and the aspect ratio of feedwells are the most critical parameters which affect the RTD of feedwell. Further simulation experiments were then carried out. Under the optimal operation conditions, the volume fraction of dead zone can reduce by10.8% and an increasement of mixing flow volume fraction by 6.5% is also observed. There is an optimum feed inlet rate depending on the feedwell design. The CFD model in conjunction with the RTD analysis then can be used as an effective tool in the design, evaluation and optimization of thickener feedwell in the red mud separation.
基金Supported by the Natural Science Foundation of Zhejiang Province(Y1100842) the Planning Projects of General Administration of Quality Supervision Inspection and Quarantine of the People's Republic of China(2006QK23)
文摘A time-frequency signal processing method for two-phase flow through a horizontal Venturi based on adaptive optimal-kernel (AOK) was presented in this paper.First,the collected dynamic differential pressure signal of gas-liquid two-phase flow was preprocessed,and then the AOK theory was used to analyze the dynamic differ-ential pressure signal.The mechanism of two-phase flow was discussed through the time-frequency spectrum.On the condition of steady water flow rate,with the increasing of gas flow rate,the flow pattern changes from bubbly flow to slug flow,then to plug flow,meanwhile,the energy distribution of signal fluctuations show significant change that energy transfer from 15-35 Hz band to 0-8 Hz band;moreover,when the flow pattern is slug flow,there are two wave peaks showed in the time-frequency spectrum.Finally,a number of characteristic variables were defined by using the time-frequency spectrum and the ridge of AOK.When the characteristic variables were visu-ally analyzed,the relationship between different combination of characteristic variables and flow patterns would be gotten.The results show that,this method can explain the law of flow in different flow patterns.And characteristic variables,defined by this method,can get a clear description of the flow information.This method provides a new way for the flow pattern identification,and the percentage of correct prediction is up to 91.11%.
文摘Objective To evaluate the efficacy of minimally invasive perventricular device closure of ventricular septal defect(VSD). Methods Between September 2011 and February 2013, we collected 40 patients who underwent perventricular closure via a small lower sternal incision(minimally invasive group), aged 15.5±3.5 years(12 months to 32 years) with a body weight of 24.2±7.5 kg(10.8-58.0 kg). The mean size of VSD was 5.6±0.5 mm(2-14 mm). Another 40 patients were included as the surgical group, receiving the conventional surgical repair of VSD. The device of the minimally invasive group was released under the guidance of transesophageal echocardiography. Success rate, cardiac indicators, and clinical outcomes of the 2 groups were compared. Results The patients in the surgical group and those in the minimally invasive group showed similar results in success rate(both 97.5%). The procedure time, intensive care unit stay, hospital stay, and postoperative recovery time in the minimally invasive group were significantly shorter than those in the surgical group(58±21 minutes versus 145±26 minutes, 2±1 days versus 8±3 days, 5±1 days versus 16±6 days, 3±1 days versus 90±20 days, all P<0.05). The minimally invasive group had a higher incidence of conduction anomalies(17.5% versus 2.5%, P<0.05). In the follow-up period of 3-12 months, there was no new residual shunt, noticeable aortic regurgitation, significant arrhythmias, or device failure except for new complications in the surgical group. Conclusions The success rate of minimally invasive perventricular device closure of VSD under transesophageal echocardiography guidance is similar to that of conventional surgical repair, but the short-term outcomes of the minimally invasive approach is much better. Long-term follow-up is necessary to confirm the effectiveness of this technique.
文摘Objective Doppler derived mitral peak early diastolic filling velocity to deceleration time ratio (E/DT) has been proposed as parameter for predicting prognosis in general population. This study prospectively investigates the incremental prognostic value of E/DT over clinical, conven- tional eehocardiographic and mitral-Doppler variables in patients hospitalized for decompensated heart failure (HF). Methods We analyzed 95 HF patients (mean age 64.8 ± 12.2 years) hospitalized at our institution from January 2010 to March 2012. The primary end-point was cardiac death or hospitalization, whichever occurred first. Cox regression analysis was performed to identify significant predictors of outcomes. Results During follow-up (median 37.7 months) 13 patients died and 44 were hospitalized for a cardiac event. At univariable analysis, New York Heart Association (NYHA) functional class, furosemide dosage, lateral tricuspidal annular plane systolic excursion, deceleration lime and E/DT were predictive of outcome. At multivariable analysis, E/DT was the only predictor of prognosis (hazard ratio = 1.02, P = 0.018), giving incremental prognostic information to clinical and other echocardio-graphic measures (global chi-square from 15.4 to 25.2; P = 0.032). Conclusions FJDT gives independent and incremental prognostic information in HF patients.
文摘Objective To evaluate left univentricular (LUV) pacing for cardiac resynchronization therapy (CRT) using a rate-adaptive atrioven- tricular delay (RAAVD) algorithm to track physiological atrioventricular delay (AVD). Methods A total of 72 patients with congestive heart failure (CHF) were randomized to RAAVD LUV pacing versus standard biventricular (BiV) pacing in a 1 : 1 ratio. Echocardiography was used to optimize AVD for both groups. The effects of sequential BiV pacing and LUV pacing with optimized A-V (right atrio-LV) delay using an RAAVD algorithm were compared. The standard deviation (SD) of the S/R ratio in lead VI at five heart rate (HR) segments (Rs/R-SD5), defined as the "tracking index," was used to evaluate the accuracy of the RAAVD algorithm for tracking physiological AVD. Results TheQRS complex duration (132 ± 9.8 vs. 138± 10ms, P 〈 0.05), the time required for optimization (21 ±5 vs. 50±8min, P〈 0.001), the mitral regurgitant area (1.9 ± 1.1 vs. 2.5 ± 1.3 em2, P 〈 0.05), the interventricular mechanical delay time (60.7 ± 13.3 ms vs. 68.3 ± 14.2 ms, P 〈 0.05), and the average annual cost (13,200 ± 1000 vs. 21,600 ± 2000 RMB, P 〈 0.001) in the RAAVD LUV pacing group were significantly less than those in the standard BiV pacing group. The aortic valve velocity-time integral in the RAAVD LUV pacing group was greater than that in the standard BiV pacing group (22.7 ± 2.2 vs. 21.4 ± 2.1 cm, P 〈 0.05). The Rs/R-SD5 was 4.08 ± 1.91 in the RAAVD LUV pacing group, and was significantly negatively correlated with improved left ventricular ejection fraction (LVEF) (ALVEF, Pearson's r = -0.427, P = 0.009), and positively correlated with New York Heart Association class (Spearman's r - 0.348, P 0.037). Conclusions RAAVD LUV pacing is as effective as standard BiV pacing, can be more physiological than standard BiV pacing, and can de- crease the average annual cost of CRT.
基金the National Natural Science Foundation,No.81270521(to Wang B)
文摘AIM To describe the prevalence of posttransplant metabolic syndrome(PTMS) after donation after cardiac death(DCD) liver transplantation(LT) and the pre-and postoperative risk factors.METHODS One hundred and forty-seven subjects who underwent DCD LT from January 2012 to February 2016 were enrolled in this study. The demographics and the clinical characteristics of pre-and post-transplantation were collected for both recipients and donors. PTMS was defined according to the 2004 Adult Treatment Panel-Ⅲ criteria. All subjects were followed monthly for the initial 6 mo after discharge, and then, every 3 mo for 2 years. The subjects were followed every 6 mo or as required after 2 years post-LT.RESULTS The prevalence of PTMS after DCD donor orthotopic LT was 20/147(13.6%). Recipient's body mass index(P = 0.024), warm ischemia time(WIT)(P = 0.045), and posttransplant hyperuricemia(P = 0.001) were significantly associated with PTMS. The change in serum uric acid levels in PTMS patients was significantly higher than that in non-PTMS patients(P < 0.001). After the 1 s t mo, the level of serum uric acid of PTMS patients rose continually over a period, while it was unaltered in non-PTMS patients. After transplantation, the level of serum uric acid in PTMS patients was not associated with renal function.CONCLUSION PTMS could occur at early stage after DCD LT with growing morbidity with the passage of time. WIT and post-LT hyperuricemia are associated with the prevalence of PTMS. An increased serum uric acid level is highly associated with PTMS and could act as a serum marker in this disease.
文摘Background Although previous studies using Korean data have already reported higher rates of mortality in women, it is less clear whether these gender differences in prognosis post ST-segment elevation myocardial infarction (STEMI), are age dependent. The aim of this study is to examine the gender-age interaction with early and late mortality in patients with STEMI enrolled in the Korean nationwide regis-try. Methods This prospective study stratified outcomes according to gender and age from 17,021 STEMI patients. We compared in-hospital, early (30 days) and late (12 months) mortality between gender to examine the gender-age interaction in multivariable models. Results In younger women (〈 60 years), in-hospital [5.8% vs. 2.5%, P 〈 0.001; unadjusted odds ratios (OR): 2.41, 95% confidence inter-vals (CI): 1.59-3.66], early (6.2% vs. 2.6%, P 〈 0.001; unadjusted OR: 2.4, 95% CI: 2.12-2.72) and late mortality (7.0% vs. 3.1%, P 〉 0.001; unadjusted OR: 2.33, 95% CI: 2.08-2.61) were significantly higher compared with men. However, after adjustment for patient characteristics, Killip class ≥ 3, symptom to balloon time and major bleeding, and in-hospital bleeding, overall early and late mortality were no longer re-lated to gender in any age groups. Conclusions Among a Korean population with STEMI, higher early and late mortality in younger women may be explained by poor patient characteristics, higher Killip class ≥3, longer symptom to balloon time and more frequent major bleeding. Therefore, based on gender-age differences, more precise and aggressive preventive strategies focused on risk factor reduction, education and more intensive management for yotmger women should be performed.
文摘Time has multiple aspects and is difficult to define as one unique entity, which therefore led to multiple interpretations in physics and philosophy. However, if the perception of time is considered as a composite time concept, it can be decomposed into basic invariable components for the perception of progressive and support-fixed time and into secondary components with possible association to unit-defined time or tense. Progressive time corresponds to Bergson's definition of duration without boundaries, which cannot be divided for measurements. Time periods are already lying in the past and fixed on different kinds of support. The human memory is the first automatic support, but any other support suitable for time registration can also be considered. The true reproduction of original time from any support requires conditions identical to the initial conditions, if not time reproduction becomes artificially modified as can be seen with a film. Time reproduction can be artificially accelerated, slowed down, extended or diminished, and also inverted from the present to the past, which only depends on the manipulation of the support, to which time is firmly linked. Tense associated to progressive and support fixed time is a psychological property directly dependent on an observer, who judges his present as immediate, his past as finished and his future as uncertain. Events can be secondarily associated to the tenses of an observer. Unit-defined time is essential for physics and normal live and is obtained by comparison of support-fixed time to systems with regular motions, like clocks. The association of time perception to time units can also be broken. Einstein's time units became relative, in quantum mechanics, some physicist eliminated time units, others maintained them. Nevertheless, even the complete elimination of time units is not identical to timelessness, since the psychological perception of progressive and support-fixed time still remains and cannot be ignored. It is not seizable by physical methods, but experienced by everybody in everyday life. Contemporary physics can only abandon the association of time units or tenses to the basic components in perceived time.
文摘Objectives: To probe some more important factors affecting the HIV epidemic by surveying the relationshipbetween AIDS high risk behaviors and childhood status,attitude/perception to gender of male/sex orientation andrare experiences/Psy-chology among Chinese gays. Methods: Data were collected from 240 Chinese gays whowere attracted by their same gender. Results: The extent of sex among China's Mainland gays issimilar to that of industrialized countries, and behaviorsthat exacerbate the HIV epidemic are universal.Perceptions 'being a girl is better',' Dislike toys likeswords or pistols in early childhood were predictors topassive anal intercourse in adulthood. Those gay men whobegan sexual intercourse younger than 16 years old tendedto have more sex partners and suffered more pain. Thosedisliked gender of male or self-regarded as female tended tohave more passive anal intercourse and related to childhoodcross-gender experience/psychology while those were raised as girls by their parentsdid not take on e above characters. Individuals who experienced sex coercion and drug abuse were the twosubgroups with the greatest high-risk behaviors. Individualswho had sex with females had the greatest number of malesex partners and were more prone to group sex. Individualswith pedophilia or gerontophilia had more casual sexpartners. Psychological problems encountered by Chinese Conclusions: The prospect of an extensive AIDSepidemic among Chinese gays does exist and somesubgroups of gays play more important roles in theepidemic. Some high risk behaviors among adult gays canbe foreseen explicitly by the predictors taking on inchildhood, and closely relate to attitude/perception, togender of male, to some rare experience/psychology.
文摘AIM:To evaluate the diagnosis of chest pain with foregut symptoms in Chinese patients. METHODS:Esophageal manometric studies, 24-h introesophageal pH monitoring and 24-h electrocardiograms(Holter electrocardiography)were performed in 61 patients with chest pain. RESULTS:Thirty-nine patients were diagnosed with non-specific esophageal motility disorders(29 patients with abnormal gastroesophageal reflux and eight patients with myocardial ischemia).Five patients had diffuse spasm of the esophagus plus abnormal gastroesophageal reflux(two patients had concomitant myocardial ischemia),and one patient was diagnosed with nutcracker esophagus. CONCLUSION:The esophageal manometric studies, 24-h intra-esophageal pH monitoring and Holter electrocardiography are significant for the differential diagnosis of chest pain,particularly in patients with foregut symptoms.In cases of esophageal motility disorders,pathological gastroesophageal reflux may be a major cause of chest pain with non-specific esophageal motility disorders.Spasm of the esophageal smooth muscle might affect the heart-coronary smooth muscle,leading to myocardial ischemia.
文摘The high order compact d if ference method is developed for solving the perturbation equations based on Navi er Stokes equations, and is used in studying complex evolution processes from w all negative pulse to the turbulent coherent structure in the channel flow. Th is method contains three dimensional coupling difference scheme with high accur acy and high resolution, and the high order time splitting methods. Compared with the general spectral method, the method can be used to research turbule nt coherent structure under more general boundary conditions and in flow domains . In this paper, the generation and evolution of the turbulent coherent structur es ind uced by wall pulse in the channel flow are simulated, and the basic characterist ics and rules of the turbulent coherent structure are shown. Computational r esults indicate that a wall negative pulse is more convenient than the resonant three wave model.
基金Work(RTI04-01-03) supported by Grant from Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.
基金Supported by Grant from the State Key Program of the National Natural Science Foundation of China,No. 81030043
文摘AIM:To evaluate pretreatment serum carcinoembryonic antigen(CEA) as a predictor of survival for patients with locally advanced gastric cancer receiving perioperative chemotherapy.METHODS:We retrospectively studied a cohort of 228 gastric cancer patients who underwent D2 gastrectomy combined with chemotherapy at the Sun Yat-sen University Cancer Center between January 2005 and December 2009.Among them,168 patients received 6-12 cycles of oxaliplatin-based adjuvant(post-operative) chemotherapy,while 60 received perioperative chemotherapy(2 cycles of FOLFOX6 or XELOX before surgery and 4-10 cycles after surgery).Serum CEA was measured using an enzyme immunoassay.The followup lasted until December 2010.RESULTS:In the group that had elevated serum CEA,the difference in survival time between patients receiving perioperative chemotherapy and those receiving adjuvant chemotherapy had no statistical significance(P > 0.05).However,in the group that had normal serum CEA,patients receiving perioperative chemotherapy had a longer survival time.In multivariate analysis,T staging and lymph node metastatic rate were independent prognostic factors for the patients.Perioperative chemotherapy improved the overall survival of patients who had a normal pretreatment CEA level(P = 0.070).CONCLUSION:Normal pretreatment serum CEA is a predictor of survival for patients receiving perioperative chemotherapy.
文摘To test the accuracy of real-time three-dimensional echocardiography (RT3DE) imaging system for evaluating left ventricular mass (LVM) in phantom and excised canine heart. Methods Ten left ventricular (LV) wall phantoms made of two rubber-bursas, ten excised canine hearts underwent RT3DE and two-dimensional echocardiography (2DE). In RT3DE "full volume" imaging, the myocardial volume was mea-sured using 2,4,8, and 16-plane method with the analysis software of RT3DE. Mass was then calculated by multiplying the resulting myocardial volume by specific density of myocardial tissue. In 2DE the masses were measured by area-length meth-od. The true LV wall phantom mass was measured by water displacement and the canine LVM was weighed by anatomy, which served as a reference standard. We compared RT3DE or 2DE with true mass. Results In LV wall phantoms, RT3DE correlated with true masses strongly (r = 0.813-0.994) and weakly correlated between 2DE and true masses (r = 0.628). In excised canine hearts, there is an excellent correlation between RT3DE and true masses (r = 0.764-0.991), while 2DE value showed a lesser correlation (r = 0.514). There are no difference between RT-3DE and true masses (P > 0.05) but different between 2DE and true masses (P < 0.05). In different planes, there was no difference between 8-plane and 16-plane (P > 0.05) but different between 8-plane and 2, 4-plane (P < 0.05). Conclusion RT3DE can accurately quantify LVM and provide a new tool to evaluate LV function. For LVM by RT3DE, 8-plane measurement method is the best choice for accuracy and convenience.
文摘The signals and the neuronal mechanisms that underlying the behavior, actions, and action-directed goals in man and animals during conscious state are not fully understood, and the neuro-dynamic mechanisms and the source of these neuronal signals are not authenticated. Temporal judgment alone can neither account for neural signaling necessary for emergence of conscious act nor explain RP (Readiness Potential, the accepted neural correlate time needed for the neurons to fire) that precedes the onset of action or the latency time of 0.5 ms that precedes the conscious act found by Libet. Neuronal feedback mechanisms between the heart and the brain seem feasible and logical suggestions to be considered, so clearly, I would suggest that the onset of a conscious-directed goal, conscious action, freewill, intension, and the neural signals and mechanisms that control them may depend upon the interaction between two sources: (1) the brain and (2) the heart. The temporal-cardiac (neural system) interaction has been well established in heart-brain interaction studies by many workers who found that the work of the heart precedes that of the brain in EEG (electroencephalography) findings in conscious stimulation, which may explain and account for RP time and the 0.5 ms latency period of Libet's important findings. According to my hypothesis (AlFaki 2009) and views, the temporal neurons in the soma to-sensory cortex will respond to conscious stimulation only after receiving neuronal signals from the cardiac neurons in the neural plexus of the heart; after variable millisecond equivalent to RP or Libet's latency period prior to temporal neuronal firinging in response to conscious act, this time is the time needed by cardiac neurons to process and signal information to the brain through feedback mechanism and heart-brain interaction.
文摘Background Studies have shown that staged percutaneous coronary intervention (PCI) for non-culprit lesions is beneficial for prog- nosis of ST-segment elevation myocardial infarction (STEMI) patients with multivessel disease. However, the optimal timing of staged re- vascularization is still controversial. This study aimed to find the optimal timing of staged revascularization. Methods A total of 428 STEMI patients with multivessel disease who underwent primary PCI and staged PCI were included. According to the time interval between primary and staged PCI, patients were divided into three groups (〈 1 week, 1- weeks, and 2-12 weeks after primary PCI). The primary endpoint was major adverse cardiovascular events (MACE), a composite of all-cause death, non-fatal re-infarction, repeat revascularization, and stroke. Cox regression model was used to assess the association between staged PCI timing and risk of MACE. Results During the follow-up, 119 participants had MACEs. There was statistical difference in MACE incidence among the three groups (〈 1 week: 23.0%; 1-2 weeks: 33.0%; 2-12 weeks: 40.0%; P = 0.001). In the multivariable adjustment model, the timing interval of staged PCI ≤ 1 week and l-2 weeks were both significantly associated with a lower risk of MACE [hazard ratio (HR): 0.40, 95% confidence intervals (CI): 0.24-4).65; HR: 0.54, 95% CI: 0.3 lq3.93, respectively], mainly attributed to a lower risk of repeat revascularization (HR: 0.41, 95% CI: 0.24-0.70; HR: 0.36, 95% CI: 0.18-0.7), compared with a strategy of 2-12 weeks later of primary PCI. Conclusions The optimal timing of staged PCI for non-culprit vessels should be within two weeks after primary PCI for STEMI patients.
基金supported jointly by the National Key Research and Development Program of China [grant number 2016YFB02008001]the National Natural Science Foundation of China [grant number 41530426]
文摘Winter North Atlantic Oscillation(NAO)indexes from observations based on various winter durations are compared.Results show that there are significant differences in the interannual and decadal variations of these NAO indexes.For the same data source,a different definition of winter duration can lead to different signs of NAO index in some years,which mainly appear to be in the period of decadal phase transition.The different winter durations induce different cycles of the observation-based NAO.The longer the winter duration,the stronger the decadal variation.The NAO defined by different winter durations also can generate different descriptions of the NAO action centers,including the position and movement.The longer the winter duration,the more southerly action centers appear to be.The movement of the action centers affects not only site-based NAO indexes but also those defined by other methods,such as empirical orthogonal function(EOF)analysis.The length of time used in EOF analysis has a great influence on the spatial pattern of the NAO mode,which results in a considerable difference between the corresponding NAO indexes.Regardless of which NAO index is used,the NAO-related SST anomalies show the same tripole pattern.The longer the winter duration,the more significant the relationship between the NAO and SST affected by the timescale of sea-air interaction.