Average Transit Time Research Articles

Variability of subsurface structure and infiltration hydrology among surface coal mine valley fills

Surface coal mining alters landscapes including creating waste-rock fills or dumps. In Appalachia USA, mines fill valleys with waste rock, constructing valley fills that affect water quality and aquatic ecology downstream. Total dissolved solids (TDS) in mine effluent are elevated from exposure of mineral surfaces to weathering. Understanding TDS variability requires understanding valley fill internal structure and its effect on hydrology, yet prior studies focused on point measurements or did not address patterns among fills. Here we investigated subsurface structure and hydrologic flowpaths in two dimensions within four valley fills using electrical resistivity imaging (ERI). We used artificial rainfall to investigate the location and transit time of preferential flowpaths through the fills. We corroborated our ERI interpretations using borehole logs, downhole video, and shallow soil excavation. ERI results indicated variability in substrate type and widespread presence of preferential flowpaths. We estimated an average preferential flowpath vertical length of 6.6 m, average transit time of water along the flowpath of 1.4 h, and average minimum water velocity of 5.1 m/h (0.14 cm/s). These rates are higher than typical for undisturbed lands, and resemble highly preferential flow in karst terrain. ERI successfully distinguished fills using conventional loose-dump construction from experimental controlled-material compacted-lift construction. Conventional fills exhibited finer particles that retain water at the surface, with larger rocks and larger voids at depth. Conventional fills had greater ranges of subsurface resistivity (i.e. substrate types) and greater interior accumulation of water during artificial rainfall, indicating more quick/deep preferential infiltration flowpaths. We show experimental construction significantly alters hydrologic response, which in combination with use of low-TDS waste rock, may affect downstream water quality relative to conventional loose-dump methods. Our soil boring and pits corroborated ERI interpretation, thus demonstrating ERI to be a robust non-invasive technique that provides reliable information on valley fill structure and hydrology.

State Estimation Using the CoG Candidates for Sit-to-Stand Support System User

Various support systems have been developed to support elderly people, and the demand for indoor support system has increased. It is important to support not only walking but also to support sit-to-stand and stand-to-sit motions. We develop a support system for indoor use that depends on the user's state, such as sitting or standing. Although it is useful for assistive devices to be able to select how to support users based on sensor data, it is difficult to utilize many expensive and sophisticated sensors for accurate estimation of the user's state. In this study, we propose an estimation method of the user's state utilizing a few inexpensive and simple sensors. First, we propose the method to calculate the CoG candidates using a human link model. The CoG candidates are then used to develop a state estimation method for sit-to-stand motion; this motion consists of three contiguous states: sitting, rising, and standing. A support vector machine is used to estimate the user state and the methods were experimentally validated using the developed assistive robot. The experimental results show that the estimations are correct except in the vicinities of state transitions. The average state transition time errors are 0.175 and 0.145 s for sit-to-rise and rise-to-stand, respectively. Since sit-to-stand motion is contiguous, the user's state is ambiguous and can be both states at the boundaries. Therefore, the accuracy of the state estimation is reasonable.

Retention of the Patency Capsule: A Complication That Deserves Attention

Video capsule (VC) endoscopy is useful in examining the entire length of small bowel for conditions like suspected Crohn's disease, complicated celiac disease, obscure GI bleeding and surveillance of polyposis syndromes. While VC endoscopy is a non-invasive, and easy-to-perform procedure, a significant complication is capsule retention. The estimated capsule retention rate is approximately 2%. The risk is 0% in healthy adults but increases to 13% in suspected Crohn's disease patients. To minimize this complication, pre-screening is performed by small bowel imaging or via a patency capsule (PC). The PC is a self-dissolving capsule: it is the same size as the video capsule and consists of a biodegradable cellophane film, containing lactose and barium sulfate. Because small-bowel imaging may not accurately predict the passage of the VC, the PC is used to determine if the VC will pass through the affected small bowel. Per the manufacturer, the PC is expected to dissolve in 30 hours post-ingestion - even if it gets lodged in the small bowel. However, one study of 30 adult patients reported the average PC transit time to be 40 hours. In one case report, it was retained for 76 hours. We report an adolescent female whose PC was was retained for 8 days. She had clinical and radiographic features suggestive of Crohns disease affecting the terminal ileum. Tissue diagnosis could not be obtained as narrowing of the ileocecal valve prevented intubation of terminal ileum. VC endoscopy was indicated to visualize the inflamed area. To predict VC passage, a PC was swallowed to assess patency of the diseased segment. The PC was retained in the right lower quadrant for 8 days (192 hours), with some decrease in size on serial X-rays even though she received a 5-day course of steroids. Contrary to the PC manufacturer specification, even after 8 days, the PC did not dissolve completely causing microperforation and peritonitis of the terminal ileum requiring resection. At surgery, the PC was visualized as an empty parchment paper-like shell in the diseased ileum. Pathology was consistent with active transmural fibrostenotic Crohns disease. Clinicians should be aware that the PC may be retained in the small bowel for longer than the manufacturer's specified time for dissolution and its persistence may lead to complications requiring surgery. This should be discussed with patients, prior to the examination, particularly those with suspected Crohn disease.

Effect of Intracranial Pressure Control on Improvement of Cerebral Perfusion After Acute Subarachnoid Hemorrhage: A Comparative Angiography Study Based on Temporal Changes of Intracranial Pressure and Systemic Pressure

Increased intracranial pressure (ICP) is a well-known complication after aneurysmal subarachnoid hemorrhage (aSAH). This study focused on the different temporal changes in ICP, mean arterial pressure, and cerebral perfusion pressure at the early stage of aSAH, throughout aneurysm embolization, and their effects on improvement in angiographic perfusion patterns. Twenty-seven patients with aSAH were evaluated who underwent coiling and cerebrospinal fluid (CSF) drainage. Diagnostic angiography was performed to confirm the presence and location of the vascular lesion. The transit time of the capillary filling phase was defined as a surrogate of cerebral perfusion. Capillary filling transit times were compared before and after CSF drainage. Univariate and multivariate analyses were performed to identify associations between different physical parameters and capillary filling transit times. By univariate analysis, average capillary transit time before CSF drainage had a significant correlation with initial ICP (P= 0.0004; R2= 0.398) but not systemic pressure (mean arterial pressure or cerebral perfusion pressure). Improvement in capillary filling pattern (i.e., a decrease in angiographic capillary transit time after CSF drainage) was seen in patients with high initial ICP and correlated with ICP difference after ventricular drainage (P= 0.0001 and P < 0.0001, respectively). Using multivariate regression analysis, improved control in postprocedural ICP levels significantly correlated with angiographic evidence of improved cerebral perfusion (P= 0.0243). Decreasing ICP by CSF drainage strongly correlated with improved cerebral microcirculation after aSAH. Further development of ICP control protocols that can provide better ICP management of patients with aSAH is warranted.

Design of PTP TC/Slave Over Seamless Redundancy Network for Power Utility Automation

IEC 61850, which drives to digitalize information in the entire system, is being increasingly adopted in the power utility industry, since the last decade. It is necessary for all devices communicating with distributed digital data to have a common understanding of time. As protection and control devices are directly related to the safety of the power system, they are strictly required to have time accuracies. This paper describes the design of a hybrid slave clock with the transparent clock (TC) functionality defined in the IEEE 1588 precision time protocol. The design objective includes not only the synchronization of the time accuracy but also the transient time, as specified in the IEC/IEEE 61850-9-3 precision time profile for power utility automation. To comply with these objectives, we adopt a hardware–software co-design approach. The timestamp of each port is implemented by hardware. Also, they are connected by hardware to calculate the bridge time on the fly, enabling the design to have a one-step TC functionality with low latency. On the other hand, the synchronizing controller is implemented by software for adapting to the varying external conditions. The controller uses the linear quadratic Gaussian (LQG) to achieve stable steady-state performance. Simultaneously, the least-squares estimator is utilized to estimate the initial conditions of the LQG controller for reducing the transition time. Experimental results show the three-sigma time inaccuracies are 15.6 ns for the TC and 149 ns for the slave with an average transition time of 13.5 s, satisfying the IEEE/IEC 61850-9-3 criteria.

Long‐Term Variation in the Mixing Fraction of Tropospheric and Stratospheric Air Masses in the Upper Tropical Tropopause Layer

AbstractObservational records of the stratospheric mean age of air (AoA), the average transit time of an air parcel since entering the stratosphere, must reflect changes in the in‐mixing from the extratropical lower stratosphere to the tropical tropopause layer (TTL). Focusing on the mixing fraction of tropospheric and stratospheric air masses in the upper TTL, the impact of mixing processes that occur prior to air masses entering the stratosphere separately from those that occur within the stratosphere is investigated. Using trajectory analysis, the mixing fraction during 1980–2016 is evaluated, and AoA and water vapor mixing ratios in the upper TTL are reconstructed. The interannual variation in the reconstructed water vapor shows good agreement with observations in the tropics. Furthermore, the reconstructed AoA exhibits long‐term variation with a positive trend between 1980 and 1999. To compare the reconstructed AoA with the observed AoA in the midlatitude stratosphere, the transit time spectra are estimated for the 1989–2016 period, and the AoA in the midlatitude stratosphere is estimated by integration of the spectrum together with the AoA in the upper TTL. As a result, although the explicitly calculated transit time shows a clear underestimation compared with previous studies, it is suggested that the “aging” effects are 3.1–4.2 years for transit time in the stratosphere, 0.2–0.7 years for in‐mixing prior to entering the stratosphere, 0.1 years for transit time from the troposphere to upper TTL, and 0.0–1.6 years for subgrid‐scale mixing in the stratosphere.

Diagnostic value of OMOM capsule endoscopy for small bowel diseases in adults.

The present study aimed to determine the diagnostic yield of OMOM capsule endoscopy for small bowel diseases in adults. A total of 89 patients, including 45 cases of obscure abdominal pain, 22 of chronic diarrhea, 18 of obscure gastrointestinal bleeding and 4 of obscure anemia were enrolled in the present study. The transit time of the endoscopy capsule in the digestive tract was recorded and the testing results were analyzed. All detections were completed except for four capsule retentions and the completion rate was 95.51%. The average transit time of the endoscopy capsule in the esophagus, stomach and small intestine was 62.18±64.23 sec, 67.46±63.13 and 346.53±102.81 min, respectively. Of the 89 patients, 54 (60.67%) were found to have lesions, among which 19 had mucosal erosion (21.35%), 15 had anabrosis (16.85%), 9 were diagnosed with polyps (10.11%), 5 with angiodysplasia (5.62%); furthermore, tumors were identified in 5 patients (5.62%) and ancylostomiasis in 1 patient (1.12%). The results confirmed the feasibility and validity of OMOM capsule endoscopy for diagnosing small bowel diseases in adults.

Assessment of Esophageal High-Resolution Impedance Manometry in Patients with Nonobstructive Dysphagia.

Background High-resolution impedance manometry (HRIM) can calculate the bolus motion parameters and the ratio of complete esophageal transit besides the conventional esophageal dynamic parameters; therefore, we could better manage the patients with nonobstructive dysphagia (NOD) clinically. Aim To analyze the HRIM parameter results of NOD patients and evaluate the characteristics of their esophageal motility and transit function. Methods In total, 58 NOD patients were assessed and the clinical diagnoses were determined. HRIM was performed, and both conventional high-resolution manometry and esophageal transit parameters were analyzed. Results In 58 NOD patients, 28 patients had achalasia, 3 esophagogastric junction outflow obstruction, and 20 nonspecific esophageal motility disorders, and 7 were normal. Impedance results demonstrated that all the patients with achalasia exhibited incomplete esophageal transit (ICET), three patients with esophagogastric junction outflow obstruction showed ICET, and the average bolus transit time (BTT) was 6.6 ± 1.2 sec. In 20 nonspecific esophageal motility disorders, 13 patients with gastroenterologly reflux disease (GERD) presented ineffective esophageal motility and fragmented peristalsis, and 65.0% swallows had exhibited ICET. However, 49.1% swallows of 7 nonspecific esophageal motility disorder patients with non-GERD had exhibited ICET. The average BTT in 13 GERD patients was longer than that in the non-GERD patients (8.1 ± 1.1 sec versus 5.5 ± 0.3 sec, P < 0.05). And in the seven patients with normal esophagus function, 3.5% swallows showed ICET and BTT was 5.6 ± 0.3 sec. Conclusion Achalasia was the most common esophageal dysmotility in NOD patients, followed by nonspecific esophageal motility disorders. The clinical diagnoses of NOD were mostly achalasia and GERD. Impedance assessments showed that all achalasia cases exhibited ICET, and other esophageal motility abnormalities that represented ICET were associated with contraction break and ineffective swallow. Compared to non-GERD patients, BTT was significantly prolonged in patients with GERD.

Ion microprobe δ18O analyses to calibrate slow growth rate speleothem records with regional δ18O records of precipitation

Paleoclimate reconstructions based on speleothems require a robust interpretation of their proxies. Detailed transfer functions of external signals to the speleothem can be obtained using models supported by monitoring data. However, the transferred signal may not be stationary due to complexity of karst processes. Therefore, robust interpretations require the calibration of speleothem records with instrumental time series lasting no less than a decade. We present the calibration of a speleothem δ18O record from Postojna Cave (Slovenia) with the regional record of δ18O composition of precipitation during the last decades. Using local meteorological data and a regional δ18O record of precipitation, we developed a model that reproduces the cave drip water δ18O signal measured during a two-year period. The model suggests that the average water mixing and transit time in the studied aquifer is 11 months. Additionally, we used an ion microprobe to study the δ18O record of the top 500 μm of a speleothem from the studied cave gallery. According to U–Th dates and 14C analyses, the uppermost section of the speleothem was formed during the last decades. The δ18O record of the top 500 μm of the speleothem has a significant correlation (r2=0.64; p-value <0.001) with the modelled δ18O record of cave drip water. Therefore, we confirm that the top 500 μm of the speleothem grew between the years 1984 and 2003 and that the speleothem accurately recorded the variability of the δ18O values of regional precipitation filtered by the aquifer. We show that the recorded speleothem δ18O signal is not seasonally biased and that the hydrological dynamics described during monitoring period were stationary during recent decades. This research demonstrates that speleothems with growth rates <50 μm/yr can also be used for calibration studies. Additionally, we show that the fit of measured and modelled proxy data can be used to achieve annually resolved chronologies in speleothems that were not actively growing at the time of collection and/or that do not record annual laminae.

Abstract B39: A pilot study to establish procedures for DNA and RNA isolation from African esophageal tumor specimens

Abstract Objective: We propose to utilize tumor biospecimens from patients with esophageal squamous cell carcinoma (ESCC) to identify possible genetic, molecular, and infectious determinants of this high-incidence disease in East Africa. However, laboratory technologies in East Africa are not available to support DNA and RNA extraction and genome and transcriptome sequencing from patient specimens. In preparation for establishment of a biorepository for African ESCC specimens, we compared different fixation and preservation media for transportability over long distances and success in preserving the genetic integrity and expression profiles of ESCC. Methods: Patients with a suspected diagnosis of ESCC at Muhimbili National Hospital in Dar es Salaam, Tanzania were identified and consented prior to endoscopic evaluations. For patients with endoscopic findings consistent with ESCC, tumor biopsies were obtained and stored using two different fixation and preservation media: PAXgene® Tissue Container (n=2) and RNAlater® (n=2). All specimens were shipped at room temperature from Dar es Salaam to San Francisco. DNA and RNA quantity was measured by nanodrop method and DNA was further confirmed by picogreen method, yielding measures of total DNA and RNA acquired (ug). DNA quality was measured as percent of total DNA degradation to between 200-1000 bp. RNA quality measure was determined by bioanalyzer output measure RNA Integrity Number (RIN). Results: Specimens for our first 10 patients were analyzed. Average transit time of biopsy specimens in preservative at room temperature was 6.2 days (range 3.5-9.0). Tumor specimens preserved with PAXgene® yielded a mean of 7.7 ug total DNA and 8.6 ug total RNA. Tumor specimens preserved with RNAlater® yielded a mean 1.4 ug of DNA and 8.2 ug of RNA. DNA degradation products were 0% of total with PAXgene® versus 6% of total with RNAlater®. Specimens preserved with PAXgene® yielded a mean RIN of 4, while RNAlater® yielded a mean RIN of 9. DNA and RNA quality were not associated with length of time at room temperature, up to a maximum of 9 days. Conclusion: Tissue preserved using the PAXgene® Tissue Container yielded higher DNA quantity and quality than tissue preserved in RNAlater®. RNA quantity was comparable for both mediums, but RNAlater® resulted in superior RNA quality versus PAXgene®. Both mediums allowed for flexible transport of specimens at room temperature and merit further inquiry into their potential as cost-effective methods to facilitate molecular analyses for geographically isolated diseases in Africa. Based upon our pilot data, each medium offers unique advantages. Our expanded study will continue to utilize both mediums to optimize isolation of both DNA and RNA. We will plan to present data for an enriched sample size. Funding source: National Institutes of Health, National Cancer Institute Cancer Center Administrative Supplement to Promote Cancer Prevention and Control Research in Low and Middle Income Countries, A119617, [CA-0082629]. Citation Format: Beatrice Paul Mushi, John Greer, Charles William Cahalane, II, Msiba Selekwa, Ali Mwanga, Larry Akoko, Elia Mmbaga, Eric Collisson, Katherine Van Loon. A pilot study to establish procedures for DNA and RNA isolation from African esophageal tumor specimens [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr B39.

Disturbance of CT perfusion within 24h after onset is associated with WFNS grade but not development of DCI in patients with aneurysmal SAH.

Delayed cerebral ischemia (DCI) is a serious complication following aneurysmal SAH (aSAH) and remains a leading cause of morbidity and mortality. We investigated whether data from CT perfusion (CTP) within 24h after onset are associated with DCI and its outcome. We retrospectively examined plain CT, CTP, and CT angiography (CTA) of aSAH patients on arrival. We measured the average mean transit time (aMTT) and compared it with several clinical factors, such as the age, WFNS grade, Fisher group, delayed cerebral infarction, cerebral vasospasm, and modified Rankin scale (mRS), at 1 month. Regions of interest (ROIs) were quantitatively determined in cortical and two basal ganglia areas. Delayed cerebral ischemia (DCI) developed in 11 patients and cerebral vasospasm in 28 patients out of a total of 86 aSAH patients scanned within 24h after onset. The average MTT was correlated with the WFNS grade (p=0.000), but not mRS (p=0.128), age (p=0.759), DCI (p=0.669), or cerebral vasospasm (p=0.306). On the other hand, DCI was associated with the Fisher group (p=0.0056), mRS (p=0.0052), and cerebral vasospasm (p=0.000). Moreover, there were no significant differences in the average MTT within 24h after onset between territories with and without DCI, or between patients with and without DCI. The current findings suggest that disturbance of CT perfusion soon after the onset is associated with the WFNS grade but not with the development of DCI. Delayed cerebral ischemia may be solely caused by cerebral vasospasm due to a clot in the cistern, but not associated with early brain injury.

Preliminary tests on dynamic characteristics of a CO2 transcritical power cycle using an expansion valve in engine waste heat recovery

CO2 has been proposed recently as working fluid for power generation from low grade heat sources due to its good thermodynamic properties and natural feature. CO2 transcritical power cycle (CTPC) is suitable for engine waste heat recovery since it has the advantage of miniaturization and better temperature matching. In this research, a constructed test bench of CTPC using an expansion valve was dynamically tested to recover exhaust energy from a heavy-duty diesel engine. CTPC system dynamic responses to mass flow rate and pressure ratio are presented in detail. Based on dynamic characteristics, a steady state detection method is proposed, which will give reference for experiments of waste heat recovery systems and make it more time-saving and economical. Results show that the CTPC system possesses good dynamic characteristics and the average transition time is less than 62 s. System high pressure or expander inlet pressure could be chosen as a representative indicator for steady state detection and experiment guidance. In addition, the test set-up is of high-accuracy and reliable after examining the heat balances over the heat exchangers and error propagation of the measurement uncertainties. CTPC is applicable for engine waste heat recovery although more efficiency improvements are needed.

A novel purgative protocol for capsule endoscopy of the small bowel produces better quality of visibility than 2 l of PEG: Timing is of the essence.

The ideal way of preparing patients for small-bowel capsule endoscopy has been controversial. Previous studies have shown that ingestion of 2 l of polyethylenglycol (PEG) 12 hours prior to capsule ingestion leads to improved visibility in comparison to no preparation at all. We speculated that using a post-ingestion (PI), booster-based cleansing protocol might provide an alternative to the PEG cleansing protocol. This randomized, blinded, prospective study enrolled 45 individuals. Patients were allocated to either of two groups. The PEG group ingested 2 l PEG 12 hours prior to the exam (n = 22) and the PI group ingested one sachet of Picolax® dissolved in 250 ml of water one hour after swallowing the capsule with 500 ml of water (n = 18). Primary endpoints were overall small bowel and distal third of small bowel cleansing levels. Secondary endpoints were average gastric and small-bowel transit time. Forty-five patients participated in this study. Five individuals were excluded because of incomplete study. Percentage of patients with adequate visibility in the distal third of the small bowel in the PEG group was 9% vs 72% in the PI group (p < 0.0001). Average gastric time and total transit time were shorter in the PI group vs the PEG group (p = 0.0065). Timing of ingestion of the Picolax® purgative 60 minutes after swallowing the capsule endoscopy delivers better visibility in the distal third of the small bowel than the accepted cleansing protocol of ingesting 2 l PEG 12 hours prior to the capsule endoscopy procedure.

Fate of microplastics and mesoplastics carried by surface currents and wind waves: A numerical model approach in the Sea of Japan

A numerical model was established to reproduce the oceanic transport processes of microplastics and mesoplastics in the Sea of Japan. A particle tracking model, where surface ocean currents were given by a combination of a reanalysis ocean current product and Stokes drift computed separately by a wave model, simulated particle movement. The model results corresponded with the field survey. Modeled results indicated the micro- and mesoplastics are moved northeastward by the Tsushima Current. Subsequently, Stokes drift selectively moves mesoplastics during winter toward the Japanese coast, resulting in increased contributions of mesoplastics south of 39°N. Additionally, Stokes drift also transports micro- and mesoplastics out to the sea area south of the subpolar front where the northeastward Tsushima Current carries them into the open ocean via the Tsugaru and Soya straits. Average transit time of modeled particles in the Sea of Japan is drastically reduced when including Stokes drift in the model.

Evaluation of drought using SPEI drought class transitions and log-linear models for different agro-ecological regions of India

Markov chain and 3-dimensional log-linear models were attempted to model drought class transitions derived from the newly developed drought index the Standardized Precipitation Evapotranspiration Index (SPEI) at a 12 month time scale for six major drought prone areas of India. Log-linear modelling approach has been used to investigate differences relative to drought class transitions using SPEI-12 time series derived form 48 yeas monthly rainfall and temperature data. In this study, the probabilities of drought class transition, the mean residence time, the 1, 2 or 3 months ahead prediction of average transition time between drought classes and the drought severity class have been derived. Seasonality of precipitation has been derived for non-homogeneous Markov chains which could be used to explain the effect of the potential retreat of drought. Quasi-association and Quasi-symmetry log-linear models have been fitted to the drought class transitions derived from SPEI-12 time series. The estimates of odds along with their confidence intervals were obtained to explain the progression of drought and estimation of drought class transition probabilities. For initial months as the drought severity increases the calculated odds shows lower value and the odds decreases for the succeeding months. This indicates that the ratio of expected frequencies of occurrence of transition from drought class to the non-drought class decreases as compared to transition to any drought class when the drought severity of the present class increases. From 3-dimensional log-linear model it is clear that during the last 24 years the drought probability has increased for almost all the six regions. The findings from the present study will immensely help to assess the impact of drought on the gross primary production and to develop future contingent planning in similar regions worldwide.

Transition Path Time Distribution, Tunneling Times, Friction, and Uncertainty.

A quantum mechanical transition path time probability distribution is formulated and its properties are studied using a parabolic barrier potential model. The average transit time is well defined and readily calculated. It is smaller than the analogous classical mechanical average transit time, vanishing at the crossover temperature. It provides a direct route for determining tunneling times. The average time may be also used to define a coarse grained momentum of the system for the passage from one side of the barrier to the other. The product of the uncertainty in this coarse grained momentum with the uncertainty in the location of the particle is shown under certain conditions to be smaller than the ℏ/2 formal uncertainty limit. The model is generalized to include friction in the form of a bilinear interaction with a harmonic bath. Using an Ohmic friction model one finds that increasing the friction, increases the transition time. Only moderate values of the reduced friction coefficient are needed for the quantum transition time and coarse grained uncertainty to approach the classical limit which is smaller than ℏ/2 when the friction is not too small. These results show how one obtains classical dynamics from a pure quantum system without invoking any further assumptions, approximations, or postulates.

机场安检系统效率的建模及应用

本文通过建立机场安检系统效率模型，探讨了在确保安全的前提下，提高旅客吞吐量和服务系统稳定性的方法。首先，运用排队系统模型，找出服务强度最大的瓶颈，并借鉴传送系统效率模型分析旅客通过瓶颈区的效率。其次，分析影响瓶颈区效率的因素，制定减压的具体计划，应用线性规划模型，获得平衡效率和成本的最优计划，并通过传送系统效率模型来验证措施的有效性。最后，筛选数据来模拟各年龄组旅客的运动，使用各年龄组的比例作为其权重来计算旅客平均通过时间。用线性插值预测2020年各年龄组的人口比例，并模拟人口老龄化的情况，使用假设检验来验证系统的敏感度，用来分析机场安检系统对特定乘客群体的适应性，提出提高服务体系的稳定性的办法。 This paper establishes the airport security system efficiency model to explore the way to improve passenger throughput and the stability of the service system in the premise of ensuring safety. Firstly, the queuing system model is used to find the bottleneck according to the service intensity, and the efficiency of the bottleneck area is verified by the transmission system efficiency model. Secondly, analyze the factors that affect the efficiency of the bottleneck area, and develop the con-crete plans of decompression, then apply the linear programming model to obtain the optimal plan of balance efficiency and cost, and verify the effectiveness of the measures through the transmission system efficiency model. Finally, the data were screened to simulate the movement of passengers in all age groups, using the proportions of the age groups as their weight to calculate the average transit time. Linearly interpolate the population of each age group in 2020, and use the hypothesis test to verify the sensitivity of the system in order to analyze the adaptability of the airport security system to specific passenger groups and propose ways to improve the stability of the service system.

Predicting neurosurgical outcomes in focal epilepsy patients using computational modelling.

SEE EISSA AND SCHEVON DOI101093/AWW332 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: Surgery can be a last resort for patients with intractable, medically refractory epilepsy. For many of these patients, however, there is substantial risk that the surgery will be ineffective. The prediction of who is likely to benefit from a surgical approach is crucial for being able to inform patients better, conduct principled prospective clinical trials, and ultimately tailor therapeutic approaches to these patients more effectively. Dynamical computational models, informed with patient data, can be used to make predictions and give mechanistic insight. In this study, we develop patient-specific dynamical network models of epileptogenic cortex. We infer the network connectivity matrix from non-seizure electrographic recordings of patients and use these connectivity matrices as the network structure in our model. The model simulates the dynamics of a bi-stable switch at every node in this network, meaning that every node starts in a background state, but has the ability to transit to a co-existing seizure state. Whether a transition happens in a node is partly determined by the stochastic nature of the input to the node, but also by the input the node receives from other connected nodes in the network. By conducting simulations with such a model, we can detect the average transition time for nodes in a given network, and therefore define nodes with a short transition time as highly epileptogenic. In a retrospective study, we found that in some patients the regions with high epileptogenicity in the model overlap with those identified clinically as the seizure onset zone. Moreover, it was found that the resection of these regions in the model reduces the overall likelihood of a seizure. Following removal of these regions in the model, we predicted surgical outcomes and compared these to actual patient outcomes. Our predictions were found to be 81.3% accurate on a dataset of 16 patients with intractable epilepsy. Intriguingly, in patients with unsuccessful outcomes, the proposed computational approach is able to suggest alternative resection sites. The model presented here gives mechanistic insight as to why surgery may be unsuccessful in some patients. This may aid clinicians in presurgical evaluation by providing a tool to explore various surgical options, offering complementary information to existing clinical techniques.

The clinical application of magnetically guided capsule endoscopy to 500 cases of gastric examination

Objective To investigate the clinical application value of magnetically guided capsule endoscopy (MGCE) to stomach examination. Methods Data of 500 patients who received MGCE examination from January 2014 to February 2016 in our hospital were retrospectively analyzed. The feasibility and safety of MGCE were studied by analyzing the detection rate of gastric lesions, transit time, adverse events, clarity and visibility, in comparison with esophagogastroduodenoscopy(EGD). Results The lesion detecting rate was 57.8%(289/500), the average transit time was (106.0±101.1)min. Overall effective rate of cleanliness was 91.8%. The visibility satisfaction rate was 98.8%. Compared with EGD, MGCE had good detection ability in stomach focal lesions. The sensitivity, specificity and accuracy were 92.0%, 85.7% and 88.3%, respectively. Except for capsule retention occurred in one patient, no other complication happened. Conclusion MGCE, stable and safe, shows high detection and accuracy rates for gastric diseases, and can be used as an effective examination tool. Key words: Capsule endoscopes; Diagnosis; Comparative study; Stomach diseases

The Porirua Protocol in the Treatment of Clozapine-Induced Gastrointestinal Hypomotility and Constipation: A Pre- and Post-Treatment Study.

Clozapine, an antipsychotic used in treatment-resistant schizophrenia, causes slow gastrointestinal transit in 50-80% of patients. Clozapine-induced gastrointestinal hypomotility is both common and serious, and potential complications include severe constipation, ileus, bowel obstruction and related complications, with a higher mortality rate than clozapine-related agranulocytosis. Little evidence exists on its prevention and management. Using a well-validated radiopaque marker ('Metcalf') method, we compared colonic transit times (CTTs) of clozapine-treated inpatients not receiving laxatives with their transit times when receiving laxatives, with treatment prescribed according to the Porirua Protocol for clozapine-related constipation (docusate and senna augmented by macrogol 3350 in treatment-resistant cases). The median age of participants was 35years, and median clozapine dose, plasma level and duration of treatment were 575mg/day, 506ng/mL and 2.5years, respectively. Overall, 14 participants (10 male) were enrolled and all completed the study. Transit times improved markedly with laxative treatment. Median colonic transit without laxatives was 110h (95% confidence interval [CI] 76-144h), over four times longer than normative values (p<0.0001). Median CTT with laxatives was 62h (95% CI 27-96h), a 2-day reduction in average transit time (p=0.009). The prevalence of gastrointestinal hypomotility decreased from 86% pre-treatment to 50% post-treatment (p=0.061). Severe gastrointestinal hypomotility decreased from 64 to 21% (p=0.031). Subjective reporting of constipation did not correlate well with objective hypomotility, and did not change significantly with treatment. Treating clozapine-treated patients with docusate and senna augmented by macrogol appears effective in reducing CTTs in clozapine-induced constipation. Randomised controlled trials are the next step. Australian New Zealand Clinical Trial Registry ACTRN12616001405404 (registered retrospectively).