Understanding the occurrence and characteristics of dry and wet events is crucial for effective disaster prevention,resource management,and risk reduction in vulnerable regions.This study analyzed the spatiotemporal p...Understanding the occurrence and characteristics of dry and wet events is crucial for effective disaster prevention,resource management,and risk reduction in vulnerable regions.This study analyzed the spatiotemporal patterns of dry-wet events and their transition characteristics in Uttar Pradesh,India.The standardized precipitation evapotranspiration index(SPEI)at a monthly timescale was utilized to identify hotspot regions vulnerable to concurrent and frequent dry and wet events and their transitions.The severity,duration,and intensity of dry and wet events were characterized with the run theory over SPEI time series data from 18 synoptic stations in Uttar Pradesh over 48 years(1971-2018),sourced from the Indian Institute of Tropical Meteorology and the India Meteorological Department.Multiple assessment methods were utilized to examine the interaction of these extreme events,considering characteristics such as wet-dry ratio,average transition time,and rapid transition times from wet to dry events and from dry to wet events.Average wet durations ranged from 1.27 to 1.58 months,and average dry durations ranged from 1.29 to 1.82 months.Rapid transition times from dry to wet events ranged from 2.5 to 4.1 months,and those for wet-to-dry events ranged from 2.1 to 5.3 months.The eastern region experienced a significantly high number of dry events,while the western and Bundelkhand regions experienced more intense dry events.In contrast,the eastern region had intense wet events.This research on the occurrence of dry-wet events and their transitions can provide valuable insights for government decision-making and disaster prevention and reduction efforts.展开更多
In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed a...In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.展开更多
AIM： To evaluate the effect of various methods of small bowel preparation on the transit time and the quality of visualization of the entire small bowel mucosa. METHODS： Ninety-five patients underwent capsule endosc...AIM： To evaluate the effect of various methods of small bowel preparation on the transit time and the quality of visualization of the entire small bowel mucosa. METHODS： Ninety-five patients underwent capsule endoscopy （CE） by easily swallowing the capsule. They were divided into three study groups according to the preparation used： group A （n = 26） by polyethylene glycol （PEG） liter or with sodium phosphate （SP） 12 h prior to the CE study; group B （n = 29） by erythromycin 1 h prior to the CE study; and group C （n = 40） without any preparation. Visualization ranged from good to satisfactory to poor. RESULTS： The gastric emptying time in the group prepared with erythromycin was shorter but without statistical significance and the small bowel transit time was unaffected. In elderly subjects prepared by PEG or SP, the gastric emptying time was significantly longer （163.7 rain, P = 0.05）. The transit times of the three sub-groups were not affected by gender or pathology. The grade of cleaning of the entire study group was 3.27±1.1. The erythromycin group presented significantly the worst quality of images （P = 0.05） compared to the other sub-groups. Age, gender, and pathology had no effect on the quality of the cleaning of the small bowel in the sub-groups. One （1.05%） case had no natural excretion. CONCLUSION： Erythromycin markedly reduces gastric emptying time, but has a negative effect on the quality of the image in the small bowel. The preparation of elderly subjects with PEG or SP has a negative effect on the small bowel transit time.展开更多
AIM: To compare the effect of oral erythromycin vs no preparation with prokinetics on the transit time and the image quality of capsule endoscopy (CE) in evaluating small bowel (SB) pathology. METHODS: We conducted a ...AIM: To compare the effect of oral erythromycin vs no preparation with prokinetics on the transit time and the image quality of capsule endoscopy (CE) in evaluating small bowel (SB) pathology. METHODS: We conducted a retrospective, blinded (to the type of preparation) review of 100 CE studies, 50 with no preparation with prokinetics from one medical center (Group A) and 50 from another center with administration of a single dose of 200 mg oral erythromycin 1 h prior to CE (Group B). Gastric, SB and total transit times were calculated, the presence of bile in the duodenum was scored, as was cleanliness within the proximal, middle and distal intestine. RESULTS: The erythromycin group had a slightly shorter gastric transit time (21 min vs 28 min, with no statistical significance). SB transit time was similar for both groups (all P > 0.05). Total transit time was almost identical in both groups. The rate of incomplete examination was 16% for Group A and 10% for Group B (P = 0.37). Bile and cleanliness scores in different parts of the intestine were similar for the two groups (P > 0.05). CONCLUSION: Preparation for capsule endoscopy with erythromycin does not affect SB or total transit time. It tends to reduce gastric transit time, but it does not increase the cecum-reaching rate. Erythromycin does not adversely affect image quality. We consider the routine use of oral erythromycin preparation as being unjustified, although it might be considered in patients with known prolonged gastric emptying time.展开更多
AIMTo define the role of small-bowel transit time in the detection rate of significant small-bowel lesions.METHODSSmall-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lom...AIMTo define the role of small-bowel transit time in the detection rate of significant small-bowel lesions.METHODSSmall-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lombardy Registry from October 2011 to December 2013, were included in the study if the clinical indication was obscure gastrointestinal bleeding and the capsule reached the cecum. Based on capsule findings, we created two groups: P2 (significant findings) and P0-1 (normal/negligible findings). Groups were compared for age, gender, small-bowel transit time, type of instrument, modality of capsule performance (outpatients vs inpatients), bowel cleanliness, and center volume.RESULTSWe retrieved and scrutinized 1,433 out of 2,295 capsule endoscopy records (62.4%) fulfilling the inclusion criteria. Patients were 67 ± 15 years old, and 815 (57%) were males. In comparison with patients in the P0-1 group, those in the P2 group (n = 776, 54%) were older (P < 0.0001), had a longer small-bowel transit time (P = 0.0015), and were more frequently examined in low-volume centers (P < 0.001). Age and small-bowel transit time were correlated (P < 0.001), with age as the sole independent predictor on multivariable analysis. Findings of the P2 group were artero-venous malformations (54.5%), inflammatory (23.6%) and protruding (10.4%) lesions, and luminal blood (11.5%).CONCLUSIONIn this selected, prospectively collected cohort of small-bowel capsule endoscopy performed for obscure gastrointestinal bleeding, a longer small-bowel transit time was associated with a higher detection rate of significant lesions, along with age and a low center volume, with age serving as an independent predictor.展开更多
BACKGROUND Slow transit constipation(STC)has traditionally been considered as a functional disorder.However,evidence is accumulating that suggests that most of the motility alterations in STC might be of a neuropathic...BACKGROUND Slow transit constipation(STC)has traditionally been considered as a functional disorder.However,evidence is accumulating that suggests that most of the motility alterations in STC might be of a neuropathic etiology.If the patient does not meet the diagnosis of pelvic outlet obstruction and poorly response to conservative treatment,surgical intervention with subtotal colectomy may be effective.The most unwanted complication of the procedure is anastomotic leakage,however,preservation of the superior rectal artery(SRA)may reduce its incidence.AIM To evaluate the preservation of the SRA in laparoscopically assisted subtotal colectomy with ileorectal anastomosis in STC patients.METHODS This was a single-center retrospective observational study.STC was diagnosed after a series of examinations which included a colonic transit test,anal manometry,a balloon expulsion test,and a barium enema.Eligible patients underwent laparoscopically assisted total colectomy with ileorectal anastomosis and were examined between January 2016 and January 2018.The operation time,blood loss,time to first flatus,length of hospital days,and incidence of minor or major complications were recorded.RESULTS A total of 32 patients(mean age,42.6 years)who had received laparoscopic assisted subtotal colectomy with ileorectal artery anastomosis and preservation of the SRA.All patients were diagnosed with STC after a series of examinations.The mean operative time was 151 min and the mean blood loss was 119 mL.The mean day of first time to flatus was 3.0 d,and the mean hospital stay was 10.6 d.There were no any patients conversions to laparotomy.Post-operative minor complications including 1 wound infection and 1 case of ileus.There was no surgical mortality.No anastomosis leakage was noted in any of the patients.CONCLUSION Laparoscopically assisted subtotal colectomy with ileorectal anastomosis and preservation of the SRA can significantly improve bowel function with careful patient selection.Sparing the SRA may protect against anastomosis leakage.展开更多
AIM： To investigate whether the small bowel transit time （SBTT） influences the diagnostic yield of capsule endoscopy （CE）. METHODS： Six hundred and ninety-one consecutive CE procedures collected in a database we...AIM： To investigate whether the small bowel transit time （SBTT） influences the diagnostic yield of capsule endoscopy （CE）. METHODS： Six hundred and ninety-one consecutive CE procedures collected in a database were analyzed. SBTT and CE findings were recorded. A running mean for the SBl-I- was calculated and correlated to the diagnostic yield with a Spearman＇s correlation test. Subgroup anal- yses were performed for the various indications for the procedure. RESULTS： There was a positive correlation between the diagnostic yield and SBT1- （Spearman＇s rho 0.58, P 〈 0.01）. Positive correlations between diagnostic yield and SB-FI-were found for the indication obscure gastro- intestinal bleeding （r = 0.54, P 〈 0.01）, for polyposis and carcinoid combined （r = 0.56, P 〈 0.01） and for the other indications （r = 0.90, P 〈0.01）, but not for suspected Crohn＇s disease （r = -0.40） CONCLUSION： The diagnostic yield in small bowel capsule endoscopy is positively correlated with the small bowel transit time. This is true for all indications except for suspected Crohn＇s disease.展开更多
Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clini...Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.展开更多
AIM： To study the esophageal transit time （ETT） and compare its mean value among three anatomical inclinations of the body; and to analyze the correlation of ETT to body mass index （BMI）. METHODS： A biomagnetic ...AIM： To study the esophageal transit time （ETT） and compare its mean value among three anatomical inclinations of the body; and to analyze the correlation of ETT to body mass index （BMI）. METHODS： A biomagnetic technique was implemented to perform this study： （1） The transit time of a magnetic marker （MM） through the esophagus was measured using two fluxgate sensors placed over the chest of 14 healthy subjects; （2） the EIF was assessed in three anatomical positions （at upright, fowler, and supine positions; 90°, 45° and 0°, respectively）. RESULTS： ANOVA and Tuckey post-hoc tests demonstrated significant differences between E-IT mean of the different positions. The ETT means were 5.2 ± 1.1 s, 6.1 ± 1.5 s, and 23.6 ± 9.2 s for 90°, 45° and 0°, respectively. Pearson correlation results were r = -0.716 and P 〈 0.001 by subjects＇ anatomical position, and r = -0.024 and P 〉 0.05 according the subject＇s BMI. CONCLUSION： We demonstrated that using this biomagnetic technique, it is possible to measure the ETT and the effects of the anatomical position on the ETT.展开更多
Objective To evaluate the feasibility of pulse transit time (PTT) arousals as an index of sleep fragmentation in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods Individuals referred for evalua...Objective To evaluate the feasibility of pulse transit time (PTT) arousals as an index of sleep fragmentation in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods Individuals referred for evaluation of possible OSAHS underwent overnight polysomnography (PSG). Three conventional indices of sleep fragmentation [electroencephalography (EEG) arousals, apnea/hypopnea index (AHI), oxygen desaturation index (ODI)], PTT arousals, and Epworth sleepiness scale (ESS) were compared. Results PTT arousals were positively correlated with EEG arousals (r= 0.746, P<0.001), AHI (r= 0.786, P<0.001), and ODI (r= 0.665, P<0.001), respectively. But, both PTT arousals and EEG arousals had no correlation with ESS (r= 0.432, P=0.201; r= 0.196, P=0.591, respectively). Conclusion PTT arousals are correlated well with other standard measures estimating severity of OSAHS and potentially a non-invasive marker with which to measure the sleep fragmentation in patients with OSAHS.展开更多
BACKGROUND Obscure small bowel bleeding is defined as gastrointestinal bleeding(GIB)that is unidentifiable with esophagogastroduodenoscopy and a colonoscopy with video capsule endoscopy(VCE)being the next gold standar...BACKGROUND Obscure small bowel bleeding is defined as gastrointestinal bleeding(GIB)that is unidentifiable with esophagogastroduodenoscopy and a colonoscopy with video capsule endoscopy(VCE)being the next gold standard step for evaluation.Small bowel transit time(SBTT)is a metric of a VCE study that is defined as the time the capsule takes to travel through the small intestine.AIM To determine if SBTT within the VCE study,correlates to overall detection of obscure small bowel bleeds.Furthermore,we attempted to identify any existing correlation between SBTT and re-bleeding after a negative VCE study.METHODS This is a single center retrospective analysis of VCE studies performed for overt and occult GIB at Einstein Medical Center,Philadelphia,between 2015 and 2019.Inclusion criteria primarily consisted of patients 18 years or older who had a VCE study done as part of the workup for a GIB.Patients with incomplete VCEs,poor preparation,or with less than 6 mo of follow up were excluded.A re-bleeding event was defined either as overt or occult within a 6-mo timeframe.Overt rebleeding was defined as Visible melena or hematochezia with>2 gm/dL drop in hemoglobin defined an overt re-bleeding event;whereas an unexplained>2 gm/dL drop in hemoglobin with no visible bleeding defined an occult re-bleed.RESULTS Results indicated that there was a significant and positive point biserial correlation between SBTT of 220 min and detection of a bleeding focus with a statistically significant p value of 0.008.However,the area under the curve was negligible when trying to identify a threshold time for SBTT to discriminate between risk of re-bleeding events after a negative VCE.CONCLUSION In terms of SBTT and association with accuracy of VCE finding a bleeding focus,220 min was found to be adequate transit time to accurately find a bleeding focus,when present.It was found that no threshold SBTT could be identified to help predict re-bleeding after a negative VCE.展开更多
Thermal behavior of bulk amorphous sulfur is investigated by in situ temperature measurements at high pressures of 0.9, 1.4 and 2.1 GPa, and under different heating rates of 8, 10 and 12K/min at 0.9 GPa. The results s...Thermal behavior of bulk amorphous sulfur is investigated by in situ temperature measurements at high pressures of 0.9, 1.4 and 2.1 GPa, and under different heating rates of 8, 10 and 12K/min at 0.9 GPa. The results show that the onset temperature of the transition from the supercooled Hquid to the liquid state for sulfur increases with the pressure and the heating rate. It is deduced that the transition does not follow the Clapeyron equation, indicating considerable coupling of the molecular structure change in the transition. Along with the data at ambient pressure and high pressure, we present a dynamic diagram to demonstrate the relationship between the amorphous solid, supercooled liquid, liquid, and crystal phases of sulfur, and suggest an experimental approach to establish pressure-temperature-time transition diagrams for supercooled liquid and liquid.展开更多
The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically.We show that,under thin airfoil assumption and fo...The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically.We show that,under thin airfoil assumption and for potential flow,the transit time difference is equal to the circulation divided by the square of the inflow velocity and the lift coefficient is equal to half of the number of chords travelled by the airfoil during the transit time difference.An analysis of transit time difference for very thick airfoil(c.f.very large angle of attack)suggests the transit time may change sign beyond thin airfoil assumption,a conclusion supported by an example of flow with an attached vortex.Thus,fluid particles may transit the upper surface with less,equal and more time than those transiting the lower surface for lift producing airfoils,depending on the configuration of flow structure and geometry.展开更多
The use of radio-opaque markers and abdominal X-ray is the standard method for determining colonic transit time(CTT). However, when there are deviations in the intake of these markers by participants in clinical trial...The use of radio-opaque markers and abdominal X-ray is the standard method for determining colonic transit time(CTT). However, when there are deviations in the intake of these markers by participants in clinical trials it is desirable to improve observations by introducingcorrections, where possible. To date, there is no standard procedure to adjust for such deviations. This report proposes a series of alternatives based on possible scenarios for deviations from the intended intake of radio-opaque markers. The proposed method to correct for missed or delayed consumption of radioopaque markers can help to increase the accuracy of the CTT measurements in clinical trials.展开更多
A recently proposed analytical hemodynamie modell[s.Fantini,Neurolmage 85,202-221(2014)]is able to predict the changes of oxy,deoxy,and total hemoglobin concentrations(model outputs)given arbitrary changes in blood fl...A recently proposed analytical hemodynamie modell[s.Fantini,Neurolmage 85,202-221(2014)]is able to predict the changes of oxy,deoxy,and total hemoglobin concentrations(model outputs)given arbitrary changes in blood flow,blood volume,and rate of oygen consumption(model inputs).One asumption of this model is that the capillary compartment is characterized by a single blood transit time.In this work,we have extended the original model by considering a distribution of capillary transit times and we have compared the outputs of both models(original and extended)for the case of sinusoidal input signals at different frequencies,which realizes the new technique of coherent hemodynamics spectroscopy(CHS).For the calculations with the original model,we have used the mean value of the distribution of capillary transit times con-sidered in the extended model.We have found that,for distributions of capillary transit times having mean values around 1 s and a standard deviation less than about 45%of the mean value,the original and extended models yield the same CHS spectra(i.e.,model outputs versus fre-quency of ocillation)within typical experimental errors.For wider capillary transit time dis-tributions,the two models yield different CHS spectra.By assuming that Poiseuille's law is valid in the capillary compartment,we have related the distribution of capillary transit times to the distributions of capillary lengths and capillary speed of blood flow to calculate the average capillary and venous saturations.We have found that,for standard deviations of the capillanry transit time distrilbution that are less than about 80%of the mean value,the average capillary saturation is always larger than the venous saturation.By contrast,the average capillary satu-ration may be less than the venous saturation for wider distributions of the capillary transit times.展开更多
Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new met...Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings： the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.展开更多
Heterojunction Bipolar Transistors with SiGe base and Si emitter and collector have increasingly become important in high speed applications in electronics due to better performance of these devices with a modest incr...Heterojunction Bipolar Transistors with SiGe base and Si emitter and collector have increasingly become important in high speed applications in electronics due to better performance of these devices with a modest increase in complexity of fabrication process. Speed of these devices is mainly determined by transit time of minority carriers across the device. Base transit time is the most important component of the total transit time. An analytical model is developed here to predict the variation of base transit time with Ge content, base doping concentration, temperature, and other device parameters. Studies have been made for both uniform and exponential doping distributions with different Ge profiles in the base region. Band gap narrowing effect due to high doping concentration is also taken into account in the model.展开更多
BACKGROUND Irritable bowel syndrome(IBS)is a bowel disorder involving abdominal pain or discomfort along with irregularity of stool form and passage frequency.The pathophysiology is poorly understood and seems to be m...BACKGROUND Irritable bowel syndrome(IBS)is a bowel disorder involving abdominal pain or discomfort along with irregularity of stool form and passage frequency.The pathophysiology is poorly understood and seems to be multifactorial.Investigations of possible causes of IBS have included only a few colonic transit studies and no simultaneous determination of the colonic faecal content.AIM To compare colon transit time and faecal load between IBS-patients and healthy control subjects.METHODS The study included 140 patients with IBS,with a mean age of 50.0 years.The control group comprised 44 healthy persons with a mean age of 43.4 years,who were selected at random from the National Civil Register.Both the patient group and the control group underwent a marker study to measure colon transit time(CTT)and to calculate a faecal loading score.The patient group underwent treatment with a combined prokinetic regime,after which their CTT and faecal loading were reassessed.Analyses were performed to compare measurements between the control group and the patient group before and after treatment.RESULTS Compared to healthy controls,IBS-patients exhibited a significantly prolonged mean CTT(45.48 h vs 24.75 h,P=0.0002)and significantly greater mean faecal loading scores in all colonic segments(P<0.001).Among IBS patients,we found no significant differences between the 48 h and 96 h radiographs.Among patients exhibiting increased CTT and faecal loading,approximately half exhibited a palpable mass in the right iliac fossa.After intervention with a prokinetic treatment,the mean CTT among IBS patients was reduced from 45.48 h to 34.50 h(P=0.091),with the post-treatment CTT not significantly differing from the CTT among control subjects(P=0.095).The faecal loading score among IBS patients did not significantly differ before and after treatment(P=0.442).The posttreatment faecal loading score in IBS patients remained significantly higher compared to that in controls(5.3 vs 4.3,P=0.014).After treatment,half of the IBSpatients were relieved of bloating,while the majority no longer experienced abdominal pain and achieved a daily consistent stool.CONCLUSION IBS-patients exhibited prolonged CTT and heavier faecal loading.These assessments may aid in diagnosis.Faecal retention may contribute to IBS symptoms,which can be treated using a prokinetic regime.展开更多
Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels i...Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels in the atom. This is done in a strictly non-probabilistic way. The time results are compared with those derived earlier on the basis of the classical Joule-Lenz law for the energy emission adapted to the case of the electron transfer in the quantum systems. A similar formalism has been next applied to the harmonic oscillator and a particle moving in the one-dimensional potential box.展开更多
The paper examines the energy of electron transitions in an emission process and the time intervals necessary for that process. For simple quantum systems, the both parameters—that of energy and time—depend on the d...The paper examines the energy of electron transitions in an emission process and the time intervals necessary for that process. For simple quantum systems, the both parameters—that of energy and time—depend on the difference Δn of the quantum numbers n labelling the beginning and end state of emission. It is shown that the phase-space areas formed by products of energy and time involved in the emission can be represented as a quadratic function of Δn multiplied by the Planck constant h.展开更多
文摘Understanding the occurrence and characteristics of dry and wet events is crucial for effective disaster prevention,resource management,and risk reduction in vulnerable regions.This study analyzed the spatiotemporal patterns of dry-wet events and their transition characteristics in Uttar Pradesh,India.The standardized precipitation evapotranspiration index(SPEI)at a monthly timescale was utilized to identify hotspot regions vulnerable to concurrent and frequent dry and wet events and their transitions.The severity,duration,and intensity of dry and wet events were characterized with the run theory over SPEI time series data from 18 synoptic stations in Uttar Pradesh over 48 years(1971-2018),sourced from the Indian Institute of Tropical Meteorology and the India Meteorological Department.Multiple assessment methods were utilized to examine the interaction of these extreme events,considering characteristics such as wet-dry ratio,average transition time,and rapid transition times from wet to dry events and from dry to wet events.Average wet durations ranged from 1.27 to 1.58 months,and average dry durations ranged from 1.29 to 1.82 months.Rapid transition times from dry to wet events ranged from 2.5 to 4.1 months,and those for wet-to-dry events ranged from 2.1 to 5.3 months.The eastern region experienced a significantly high number of dry events,while the western and Bundelkhand regions experienced more intense dry events.In contrast,the eastern region had intense wet events.This research on the occurrence of dry-wet events and their transitions can provide valuable insights for government decision-making and disaster prevention and reduction efforts.
基金The Soft Science Research Project of Ministry of Housing and Urban-Rural Development of China (No. 2008-k5-14)
文摘In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.
文摘AIM： To evaluate the effect of various methods of small bowel preparation on the transit time and the quality of visualization of the entire small bowel mucosa. METHODS： Ninety-five patients underwent capsule endoscopy （CE） by easily swallowing the capsule. They were divided into three study groups according to the preparation used： group A （n = 26） by polyethylene glycol （PEG） liter or with sodium phosphate （SP） 12 h prior to the CE study; group B （n = 29） by erythromycin 1 h prior to the CE study; and group C （n = 40） without any preparation. Visualization ranged from good to satisfactory to poor. RESULTS： The gastric emptying time in the group prepared with erythromycin was shorter but without statistical significance and the small bowel transit time was unaffected. In elderly subjects prepared by PEG or SP, the gastric emptying time was significantly longer （163.7 rain, P = 0.05）. The transit times of the three sub-groups were not affected by gender or pathology. The grade of cleaning of the entire study group was 3.27±1.1. The erythromycin group presented significantly the worst quality of images （P = 0.05） compared to the other sub-groups. Age, gender, and pathology had no effect on the quality of the cleaning of the small bowel in the sub-groups. One （1.05%） case had no natural excretion. CONCLUSION： Erythromycin markedly reduces gastric emptying time, but has a negative effect on the quality of the image in the small bowel. The preparation of elderly subjects with PEG or SP has a negative effect on the small bowel transit time.
文摘AIM: To compare the effect of oral erythromycin vs no preparation with prokinetics on the transit time and the image quality of capsule endoscopy (CE) in evaluating small bowel (SB) pathology. METHODS: We conducted a retrospective, blinded (to the type of preparation) review of 100 CE studies, 50 with no preparation with prokinetics from one medical center (Group A) and 50 from another center with administration of a single dose of 200 mg oral erythromycin 1 h prior to CE (Group B). Gastric, SB and total transit times were calculated, the presence of bile in the duodenum was scored, as was cleanliness within the proximal, middle and distal intestine. RESULTS: The erythromycin group had a slightly shorter gastric transit time (21 min vs 28 min, with no statistical significance). SB transit time was similar for both groups (all P > 0.05). Total transit time was almost identical in both groups. The rate of incomplete examination was 16% for Group A and 10% for Group B (P = 0.37). Bile and cleanliness scores in different parts of the intestine were similar for the two groups (P > 0.05). CONCLUSION: Preparation for capsule endoscopy with erythromycin does not affect SB or total transit time. It tends to reduce gastric transit time, but it does not increase the cecum-reaching rate. Erythromycin does not adversely affect image quality. We consider the routine use of oral erythromycin preparation as being unjustified, although it might be considered in patients with known prolonged gastric emptying time.
文摘AIMTo define the role of small-bowel transit time in the detection rate of significant small-bowel lesions.METHODSSmall-bowel capsule endoscopy records, prospectively collected from 30 participating centers in the Lombardy Registry from October 2011 to December 2013, were included in the study if the clinical indication was obscure gastrointestinal bleeding and the capsule reached the cecum. Based on capsule findings, we created two groups: P2 (significant findings) and P0-1 (normal/negligible findings). Groups were compared for age, gender, small-bowel transit time, type of instrument, modality of capsule performance (outpatients vs inpatients), bowel cleanliness, and center volume.RESULTSWe retrieved and scrutinized 1,433 out of 2,295 capsule endoscopy records (62.4%) fulfilling the inclusion criteria. Patients were 67 ± 15 years old, and 815 (57%) were males. In comparison with patients in the P0-1 group, those in the P2 group (n = 776, 54%) were older (P < 0.0001), had a longer small-bowel transit time (P = 0.0015), and were more frequently examined in low-volume centers (P < 0.001). Age and small-bowel transit time were correlated (P < 0.001), with age as the sole independent predictor on multivariable analysis. Findings of the P2 group were artero-venous malformations (54.5%), inflammatory (23.6%) and protruding (10.4%) lesions, and luminal blood (11.5%).CONCLUSIONIn this selected, prospectively collected cohort of small-bowel capsule endoscopy performed for obscure gastrointestinal bleeding, a longer small-bowel transit time was associated with a higher detection rate of significant lesions, along with age and a low center volume, with age serving as an independent predictor.
基金This study protocol was reviewed and approved by the Institutional Review Board of the Taiwan Adventist Hospital(TAHIRB No.:105-E-10).
文摘BACKGROUND Slow transit constipation(STC)has traditionally been considered as a functional disorder.However,evidence is accumulating that suggests that most of the motility alterations in STC might be of a neuropathic etiology.If the patient does not meet the diagnosis of pelvic outlet obstruction and poorly response to conservative treatment,surgical intervention with subtotal colectomy may be effective.The most unwanted complication of the procedure is anastomotic leakage,however,preservation of the superior rectal artery(SRA)may reduce its incidence.AIM To evaluate the preservation of the SRA in laparoscopically assisted subtotal colectomy with ileorectal anastomosis in STC patients.METHODS This was a single-center retrospective observational study.STC was diagnosed after a series of examinations which included a colonic transit test,anal manometry,a balloon expulsion test,and a barium enema.Eligible patients underwent laparoscopically assisted total colectomy with ileorectal anastomosis and were examined between January 2016 and January 2018.The operation time,blood loss,time to first flatus,length of hospital days,and incidence of minor or major complications were recorded.RESULTS A total of 32 patients(mean age,42.6 years)who had received laparoscopic assisted subtotal colectomy with ileorectal artery anastomosis and preservation of the SRA.All patients were diagnosed with STC after a series of examinations.The mean operative time was 151 min and the mean blood loss was 119 mL.The mean day of first time to flatus was 3.0 d,and the mean hospital stay was 10.6 d.There were no any patients conversions to laparotomy.Post-operative minor complications including 1 wound infection and 1 case of ileus.There was no surgical mortality.No anastomosis leakage was noted in any of the patients.CONCLUSION Laparoscopically assisted subtotal colectomy with ileorectal anastomosis and preservation of the SRA can significantly improve bowel function with careful patient selection.Sparing the SRA may protect against anastomosis leakage.
基金Supported by A clinical fellow grant(90700281)from the Netherlands Organization for Scientific Research(NWO)
文摘AIM： To investigate whether the small bowel transit time （SBTT） influences the diagnostic yield of capsule endoscopy （CE）. METHODS： Six hundred and ninety-one consecutive CE procedures collected in a database were analyzed. SBTT and CE findings were recorded. A running mean for the SBl-I- was calculated and correlated to the diagnostic yield with a Spearman＇s correlation test. Subgroup anal- yses were performed for the various indications for the procedure. RESULTS： There was a positive correlation between the diagnostic yield and SBT1- （Spearman＇s rho 0.58, P 〈 0.01）. Positive correlations between diagnostic yield and SB-FI-were found for the indication obscure gastro- intestinal bleeding （r = 0.54, P 〈 0.01）, for polyposis and carcinoid combined （r = 0.56, P 〈 0.01） and for the other indications （r = 0.90, P 〈0.01）, but not for suspected Crohn＇s disease （r = -0.40） CONCLUSION： The diagnostic yield in small bowel capsule endoscopy is positively correlated with the small bowel transit time. This is true for all indications except for suspected Crohn＇s disease.
基金supported mainly by the “Agence de la Biomedecine” through its program of Research(AOR 2009)BM,AC,BP,WM,VCI and VE acknowledged funding of project ANR-13-TECS-0006 by the Agence Nationale de la Recherche
文摘Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.
文摘AIM： To study the esophageal transit time （ETT） and compare its mean value among three anatomical inclinations of the body; and to analyze the correlation of ETT to body mass index （BMI）. METHODS： A biomagnetic technique was implemented to perform this study： （1） The transit time of a magnetic marker （MM） through the esophagus was measured using two fluxgate sensors placed over the chest of 14 healthy subjects; （2） the EIF was assessed in three anatomical positions （at upright, fowler, and supine positions; 90°, 45° and 0°, respectively）. RESULTS： ANOVA and Tuckey post-hoc tests demonstrated significant differences between E-IT mean of the different positions. The ETT means were 5.2 ± 1.1 s, 6.1 ± 1.5 s, and 23.6 ± 9.2 s for 90°, 45° and 0°, respectively. Pearson correlation results were r = -0.716 and P 〈 0.001 by subjects＇ anatomical position, and r = -0.024 and P 〉 0.05 according the subject＇s BMI. CONCLUSION： We demonstrated that using this biomagnetic technique, it is possible to measure the ETT and the effects of the anatomical position on the ETT.
文摘Objective To evaluate the feasibility of pulse transit time (PTT) arousals as an index of sleep fragmentation in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods Individuals referred for evaluation of possible OSAHS underwent overnight polysomnography (PSG). Three conventional indices of sleep fragmentation [electroencephalography (EEG) arousals, apnea/hypopnea index (AHI), oxygen desaturation index (ODI)], PTT arousals, and Epworth sleepiness scale (ESS) were compared. Results PTT arousals were positively correlated with EEG arousals (r= 0.746, P<0.001), AHI (r= 0.786, P<0.001), and ODI (r= 0.665, P<0.001), respectively. But, both PTT arousals and EEG arousals had no correlation with ESS (r= 0.432, P=0.201; r= 0.196, P=0.591, respectively). Conclusion PTT arousals are correlated well with other standard measures estimating severity of OSAHS and potentially a non-invasive marker with which to measure the sleep fragmentation in patients with OSAHS.
文摘BACKGROUND Obscure small bowel bleeding is defined as gastrointestinal bleeding(GIB)that is unidentifiable with esophagogastroduodenoscopy and a colonoscopy with video capsule endoscopy(VCE)being the next gold standard step for evaluation.Small bowel transit time(SBTT)is a metric of a VCE study that is defined as the time the capsule takes to travel through the small intestine.AIM To determine if SBTT within the VCE study,correlates to overall detection of obscure small bowel bleeds.Furthermore,we attempted to identify any existing correlation between SBTT and re-bleeding after a negative VCE study.METHODS This is a single center retrospective analysis of VCE studies performed for overt and occult GIB at Einstein Medical Center,Philadelphia,between 2015 and 2019.Inclusion criteria primarily consisted of patients 18 years or older who had a VCE study done as part of the workup for a GIB.Patients with incomplete VCEs,poor preparation,or with less than 6 mo of follow up were excluded.A re-bleeding event was defined either as overt or occult within a 6-mo timeframe.Overt rebleeding was defined as Visible melena or hematochezia with>2 gm/dL drop in hemoglobin defined an overt re-bleeding event;whereas an unexplained>2 gm/dL drop in hemoglobin with no visible bleeding defined an occult re-bleed.RESULTS Results indicated that there was a significant and positive point biserial correlation between SBTT of 220 min and detection of a bleeding focus with a statistically significant p value of 0.008.However,the area under the curve was negligible when trying to identify a threshold time for SBTT to discriminate between risk of re-bleeding events after a negative VCE.CONCLUSION In terms of SBTT and association with accuracy of VCE finding a bleeding focus,220 min was found to be adequate transit time to accurately find a bleeding focus,when present.It was found that no threshold SBTT could be identified to help predict re-bleeding after a negative VCE.
基金Supported by the National Natural Science Foundation of China under Grant No 11004163the Fundamental Research Funds for the Central Universities under Grant No 2682014ZT31
文摘Thermal behavior of bulk amorphous sulfur is investigated by in situ temperature measurements at high pressures of 0.9, 1.4 and 2.1 GPa, and under different heating rates of 8, 10 and 12K/min at 0.9 GPa. The results show that the onset temperature of the transition from the supercooled Hquid to the liquid state for sulfur increases with the pressure and the heating rate. It is deduced that the transition does not follow the Clapeyron equation, indicating considerable coupling of the molecular structure change in the transition. Along with the data at ambient pressure and high pressure, we present a dynamic diagram to demonstrate the relationship between the amorphous solid, supercooled liquid, liquid, and crystal phases of sulfur, and suggest an experimental approach to establish pressure-temperature-time transition diagrams for supercooled liquid and liquid.
基金supported partly by the National Key Project of China(No.GJXM92579)the National Science and Technology Major Project of China(No.2017-II-003-0015)the National Natural Science Foundation of China(No.11721202)。
文摘The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically.We show that,under thin airfoil assumption and for potential flow,the transit time difference is equal to the circulation divided by the square of the inflow velocity and the lift coefficient is equal to half of the number of chords travelled by the airfoil during the transit time difference.An analysis of transit time difference for very thick airfoil(c.f.very large angle of attack)suggests the transit time may change sign beyond thin airfoil assumption,a conclusion supported by an example of flow with an attached vortex.Thus,fluid particles may transit the upper surface with less,equal and more time than those transiting the lower surface for lift producing airfoils,depending on the configuration of flow structure and geometry.
文摘The use of radio-opaque markers and abdominal X-ray is the standard method for determining colonic transit time(CTT). However, when there are deviations in the intake of these markers by participants in clinical trials it is desirable to improve observations by introducingcorrections, where possible. To date, there is no standard procedure to adjust for such deviations. This report proposes a series of alternatives based on possible scenarios for deviations from the intended intake of radio-opaque markers. The proposed method to correct for missed or delayed consumption of radioopaque markers can help to increase the accuracy of the CTT measurements in clinical trials.
基金supported by the National Institutes of Health (Grant No.R01-CA154774)by the National Science Foundation (Award No.IIS1065154).
文摘A recently proposed analytical hemodynamie modell[s.Fantini,Neurolmage 85,202-221(2014)]is able to predict the changes of oxy,deoxy,and total hemoglobin concentrations(model outputs)given arbitrary changes in blood flow,blood volume,and rate of oygen consumption(model inputs).One asumption of this model is that the capillary compartment is characterized by a single blood transit time.In this work,we have extended the original model by considering a distribution of capillary transit times and we have compared the outputs of both models(original and extended)for the case of sinusoidal input signals at different frequencies,which realizes the new technique of coherent hemodynamics spectroscopy(CHS).For the calculations with the original model,we have used the mean value of the distribution of capillary transit times con-sidered in the extended model.We have found that,for distributions of capillary transit times having mean values around 1 s and a standard deviation less than about 45%of the mean value,the original and extended models yield the same CHS spectra(i.e.,model outputs versus fre-quency of ocillation)within typical experimental errors.For wider capillary transit time dis-tributions,the two models yield different CHS spectra.By assuming that Poiseuille's law is valid in the capillary compartment,we have related the distribution of capillary transit times to the distributions of capillary lengths and capillary speed of blood flow to calculate the average capillary and venous saturations.We have found that,for standard deviations of the capillanry transit time distrilbution that are less than about 80%of the mean value,the average capillary saturation is always larger than the venous saturation.By contrast,the average capillary satu-ration may be less than the venous saturation for wider distributions of the capillary transit times.
基金This work was supported by the Project of Scientific Research of the Education Department of Liaoning Province,PRC(No.202023083).
文摘Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings： the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.
文摘Heterojunction Bipolar Transistors with SiGe base and Si emitter and collector have increasingly become important in high speed applications in electronics due to better performance of these devices with a modest increase in complexity of fabrication process. Speed of these devices is mainly determined by transit time of minority carriers across the device. Base transit time is the most important component of the total transit time. An analytical model is developed here to predict the variation of base transit time with Ge content, base doping concentration, temperature, and other device parameters. Studies have been made for both uniform and exponential doping distributions with different Ge profiles in the base region. Band gap narrowing effect due to high doping concentration is also taken into account in the model.
文摘BACKGROUND Irritable bowel syndrome(IBS)is a bowel disorder involving abdominal pain or discomfort along with irregularity of stool form and passage frequency.The pathophysiology is poorly understood and seems to be multifactorial.Investigations of possible causes of IBS have included only a few colonic transit studies and no simultaneous determination of the colonic faecal content.AIM To compare colon transit time and faecal load between IBS-patients and healthy control subjects.METHODS The study included 140 patients with IBS,with a mean age of 50.0 years.The control group comprised 44 healthy persons with a mean age of 43.4 years,who were selected at random from the National Civil Register.Both the patient group and the control group underwent a marker study to measure colon transit time(CTT)and to calculate a faecal loading score.The patient group underwent treatment with a combined prokinetic regime,after which their CTT and faecal loading were reassessed.Analyses were performed to compare measurements between the control group and the patient group before and after treatment.RESULTS Compared to healthy controls,IBS-patients exhibited a significantly prolonged mean CTT(45.48 h vs 24.75 h,P=0.0002)and significantly greater mean faecal loading scores in all colonic segments(P<0.001).Among IBS patients,we found no significant differences between the 48 h and 96 h radiographs.Among patients exhibiting increased CTT and faecal loading,approximately half exhibited a palpable mass in the right iliac fossa.After intervention with a prokinetic treatment,the mean CTT among IBS patients was reduced from 45.48 h to 34.50 h(P=0.091),with the post-treatment CTT not significantly differing from the CTT among control subjects(P=0.095).The faecal loading score among IBS patients did not significantly differ before and after treatment(P=0.442).The posttreatment faecal loading score in IBS patients remained significantly higher compared to that in controls(5.3 vs 4.3,P=0.014).After treatment,half of the IBSpatients were relieved of bloating,while the majority no longer experienced abdominal pain and achieved a daily consistent stool.CONCLUSION IBS-patients exhibited prolonged CTT and heavier faecal loading.These assessments may aid in diagnosis.Faecal retention may contribute to IBS symptoms,which can be treated using a prokinetic regime.
文摘Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels in the atom. This is done in a strictly non-probabilistic way. The time results are compared with those derived earlier on the basis of the classical Joule-Lenz law for the energy emission adapted to the case of the electron transfer in the quantum systems. A similar formalism has been next applied to the harmonic oscillator and a particle moving in the one-dimensional potential box.
文摘The paper examines the energy of electron transitions in an emission process and the time intervals necessary for that process. For simple quantum systems, the both parameters—that of energy and time—depend on the difference Δn of the quantum numbers n labelling the beginning and end state of emission. It is shown that the phase-space areas formed by products of energy and time involved in the emission can be represented as a quadratic function of Δn multiplied by the Planck constant h.
