Numerical simulation study on pore clogging of pervious concrete pavement based on different aggregate gradation

Pervious concrete (PC) pavements can effectively reduce surface runoff, but it will be clogged with time and its service life will be affected. In this study, based on three groups of PC specimens with different aggregate gradations optimized by previous experiments, the pavement-clogging simulation test is carried out using the two-way coupling of the particle flow code with computational fluid dynamics (PFC-CFD). The results show that when the gradation of aggregates in the pervious pavement is different, the volume fraction of clogging material in the pavement and the time when the volume fraction of the clogging material reaches the maximum are also different. It is related to the zigzag degree and size of the pore in the pervious pavement. The smaller the particle size of coarse aggregate in the pervious pavement, the easier it is to be clogged, and the discontinuous graded coarse aggregate has a good shielding effect on the clogging material. Different clogging material gradations have different effects on the clogging of pervious pavements. According to the aforementioned research results, researchers can select different mix ratios of anti-clogging PC according to different areas of use. The law obtained from the experiment can provide a reference for further study of the double-layer pervious pavement structure design

First Results of the QUENCH-ALISA Bundle Test

The bundle experiment QUENCH-18 on air ingress and aerosol release was successfully conducted at KIT in the frame of the EC supported ALISA program. The primary aims were to examine the oxidation of M5® claddings in air/steam mixture following a limited pre-oxidation in steam, and to achieve a long period of oxygen and steam starvations to promote interaction with the nitrogen. Additionally, the QUENCH-18 experiment investigated the effects of the presence of two Ag-In-Cd control rods, and two pressured unheated rod simulators (60 bar, He). The low-pressurized heater rods (2.3 bar, similar to the system pressure) were Kr-filled. In a first transient, the bundle was heated in an atmosphere of flowing argon and superheated steam by electrical power increase to the peak cladding temperature of 1400 K. During this heat-up, claddings of the two pressurized rods were burst at temperature of 1045 K. The attainment of 1400 K marked the start of the pre-oxidation phase to achieve a maximum cladding oxide layer thickness of about 100 µm. In the air ingress phase, the steam and argon flows were reduced, and air was injected. The first Ag-In-Cd aerosol release was registered at 1350 K and was dominated by Cd bearing aerosols. Later in the transient, a significant release of Ag was observed. A strong temperature escalation started in the middle of the air ingress phase. Later a period of oxygen starvation occurred and was followed by almost complete steam consumption and partial consumption of the nitrogen. Following this, the temperatures continued to increase and stabilized at melting temperature of Zr bearing materials until water injection. Almost immediately after the start of reflood there was a temperature excursion, leading to maximum measured temperatures of about 2450 K. Final quench was achieved after about 800 s. A significant quantity of hydrogen was generated during the reflood (238 g). Nitrogen release (>54 g) due to re-oxidation of nitrides was also registered

Statistical Properties of High-Speed Train Wireless Channels in Different Scenarios

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.In this paper, we compare the statistical properties of high-speed train (HST) wireless channels in different scenarios using a generic non-stationary HST channel model that has been verified by channel measurements (Ghazal et al., 2015). We mainly focus our comparison and analysis on the three most common HST scenarios, i.e., the rural area, cutting, and viaduct scenarios. Several channel statistical properties such as the temporal autocorrelation function (ACF), space cross-correlation function (CCF), and space- Doppler (SD) power spectrum density (PSD) are investigated. The impacts of different scenario- specific parameters on the channel statistical properties are also studied via numerical analysis

Channel Measurements and Models for High-Speed Train Wireless Communication Systems in Tunnel Scenarios: A Survey

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The rapid developments of high-speed trains (HSTs) introduce new challenges to HST wireless communication systems. Realistic HST channel models play a critical role in designing and evaluating HST communication systems. Due to the length limitation, bounding of tunnel itself, and waveguide effect, channel characteristics in tunnel scenarios are very different from those in other HST scenarios. Therefore, accurate tunnel channel models considering both large-scale and small-scale fading characteristics are essential for HST communication systems. Moreover, certain characteristics of tunnel channels have not been investigated sufficiently. This article provides a comprehensive review of the measurement campaigns in tunnels and presents some tunnel channel models using various modeling methods. Finally, future directions in HST tunnel channel measurements and modeling are discussed

Study on evolution law of mechanical properties of coal samples subjected to freezing and freeze-thaw cycles of liquid nitrogen

The permeability of coal reservoir is generally low in China, how to effectively improve the permeability of coal reservoir is a key and difficult point of coalbed methane exploitation, Liquid nitrogen fracturing technology as a kind waterless fracturing technology has received extensive attention in recent years. In order to reveal the influence of liquid nitrogen freezing and freeze-thaw on the mechanical properties of coal, the temperature distribution of coal samples was monitored by infrared thermal imaging technology, and uniaxial compression and acoustic emission tests were performed on the coal samples after the liquid nitrogen freezing and freezethaw, the P-wave velocity, porosity, acoustic emission and energy evolution characteristics of coal samples before and after the freezing and freeze thaw were analyzed. The research result showed that: ①After 360 min freezing and 12 freeze-thaw cycles, the P-wave velocity of coal samples decreased by 58.2% and 64.7%, respectively. The P-wave velocity does not decrease significantly during the initial freezing and freeze-thaw cycle stages, the velocity gradually decreases with the increase of freezing time and freeze-thaw cycles. ②The temperature of the coal sample gradually decreases with increase of freezing times. The surface temperature of the coal sample drops below -60°C after the liquid nitrogen frozen for 180s, the temperature distribution fluctuations at the center of the coal sample occurs due to the different thermal conduction coefficient of the coal particles. ③After liquid nitrogen freezing and freezethaw, the elastic modulus of coal sample decreases exponentially, while the porosity gradually increases. The increase in porosity of the coal sample after liquid nitrogen freeze-thaw is greater than that after liquid nitrogen freezing. ④The acoustic emission activity of coal samples during uniaxial loading is divided into development phase, active phase and severe phase, the maximum acoustic emission ringing count and cumulative acoustic emission ringing count of coal samples increase with the increase of freezing time and freeze-thaw cycles. ⑤Liquid nitrogen freezing and freeze-thaw will weaken the energy storage limit of coal sample, resulting in the reduction of the total energy, elastic energy and dissipated energy at the peak point during the uniaxial loading process

High throughput Single-cell Cultivation on Microfluidic Streak Plates

This paper describes the microfluidic streak plate (MSP), a facile method for high-throughput microbial cell separation and cultivation in nanoliter sessile droplets. The MSP method builds upon the conventional streak plate technique by using microfluidic devices to generate nanoliter droplets that can be streaked manually or robotically onto petri dishes prefilled with carrier oil for cultivation of single cells. In addition, chemical gradients could be encoded in the droplet array for comprehensive dose-response analysis. The MSP method was validated by using single-cell isolation of Escherichia coli and antimicrobial susceptibility testing of Pseudomonas aeruginosa PAO1. The robustness of the MSP work flow was demonstrated by cultivating a soil community that degrades polycyclic aromatic hydrocarbons. Cultivation in droplets enabled detection of the richest species diversity with better coverage of rare species. Moreover, isolation and cultivation of bacterial strains by MSP led to the discovery of several species with high degradation efficiency, including four Mycobacterium isolates and a previously unknown fluoranthene-degrading Blastococcus species

Impact of Cardiovascular Risk Factors on Carotid Intima-Media Thickness and Degree of Severity: A Cross-Sectional Study

OBJECTIVE: Age, hypertension, dyslipidemia and diabetes are common cardiovascular risk factors (CVRFs) that contribute to the development of atherosclerosis in cardiovascular system including carotid artery disease. However, the impact of these risk factors on the increased carotid intima-media thickness (cIMT) and degree of carotid severity remains to be further clarified. This study aims to evaluate the relationship between CVRFs and degree of carotid severity and cIMT in high-risk subjects. METHODS: Four thousand and three hundred ninety-four subjects with one or more risk factors were retrospectively reviewed in this study. Patients were divided into different groups based on age, the type and quantity of CVRFs. cIMT and degree of carotid artery stenosis were measured and analyzed based on carotid ultrasound imaging with findings compared to the CVRFs to determine the correlation between these variables. RESULTS: Aging was significantly associated with degree of severity (P < 0.05) and cIMT was significantly increased with age (P < 0.05). Individual CVRF analysis shows that hypertension was more related to the degree of severity than dyslipidemia and diabetes with corresponding abnormal cIMT rates being 79.39%, 72.98% and 32.37%, respectively. The prevalence of carotid atherosclerosis were 20.06%, 22.88% and 28.63%, respectively corresponding to patients with zero, one and more than one chronic diseases. The percentage of abnormal cIMT in hypertensive patient group with dyslipidemia is significantly higher than the other groups (P< 0.05). CONCLUSIONS: This study shows a direct correlation between the degree of carotid severity and cIMT and cardiovascular risk factors, especially with age and hypertension. Carotid atherosclerosis is closely related to the number of cardiovascular risk factors

Identifying Effective Interventions To Improve Quality Of Care For Patients With Hepatocellular Carcinoma

Introduction: Hepatocellular carcinoma (HCC) requires complex care coordination that can cause delays at many points in the care process. Patient safety may be compromised with untimely follow-up of abnormal liver imaging results. At many tertiary care institutions, optimal treatment is planned at a multidisciplinary liver tumor board (MDLTB). At many tertiary care centers, patients suspected for HCC would immediately be referred to the internal MDLTB for workup and management (internal patients). However, many community hospitals lack the resources to conduct effective MDLTBs. Thus, HCC patients discovered by community providers are often referred externally to nearby tertiary care centers for continued care (external patients). As the timing of external referrals is at individual provider\u27s discretion, the external referral process can create delays and result in different quality of care received for external patients compared to internal patients. This project consists of two studies that examine factors that can reduce quality of care for patients with HCC, such as delayed timeliness of diagnosis and treatment, and explore potential interventions that can improve this care process. The first study evaluated whether the implementation of an electronic medical record-linked abnormal imaging identification and tracking system at a Veterans Hospital improved timeliness and quality of HCC care. The tracking system studied reviewed all liver radiology reports daily via diagnostic codes and natural language processing of reports, generated a queue of abnormal cases for care coordinators to review, and provided a tracking feature to monitor each patient’s care progress. The second study compares internal vs. external patients discussed at a tertiary care center MDLTB to determine whether external patients received lower quality of care compared to internal patients. Method: For the first study, we designed a retrospective pre-/post-test study to evaluate whether implementation of this tracking system reduced time between HCC diagnosis and treatment, as well as time between first suspicious image and first specialty-care appointment, diagnosis, and treatment. We compared patients diagnosed with HCC in the 36-months before tracking system implementation (pre-intervention) to patients diagnosed with HCC in the 72-months (less a 12-month grace period) after tracking system implementation (post-intervention). We used multivariable regression models, unpaired t-test, Wilcoxon rank-sum test, product limit estimator, and Fisher’s exact test to calculate statistical significance. For the second study, we designed a retrospective comparative cohort study to compare internal and external patients to see whether external patients received a lower quality of care for HCC management. We reviewed incident HCC cases presented over three years at an American College of Surgeons accredited MDLTB. Internal patients were defined as patients whose care originated within the tertiary care institution of the MDLTB; external patients were defined as patients who received initial care from outside institutions and referred to the tertiary care MDLTB for consultation. Differences in care quality were measured by [1] receiving delayed timeliness of care, [2] undergoing unnecessary diagnostic studies, [3] receiving different first treatments, and [4] showing reduced survival. Results: For the first study, 60 patients were included in the pre-intervention period and 130 in the post-intervention period. Compared to the pre-intervention cohort, time-elapsed for the post-intervention cohort was reduced from 85.0 to 56.2 days from diagnosis-to-treatment (p\u3c0.05), 86.4 to 39.4 days from imaging-to-diagnosis (p\u3c0.01), and 171.3 to 95.6 days from imaging-to-treatment (p\u3c0.01). For the second study, 122 internal cases and 170 external cases were included. Compared to internal cases, external cases took significantly more time to be diagnosed with HCC (4.5 vs. 38 days, p\u3c0.001) and to be discussed at MDLTB (20 vs. 56 days, p\u3c0.001). Internal cases were more often diagnosed by imaging studies (78%), while external cases were more often diagnosed by biopsy (42%) or by consensus of experts at MDLTB (26%). Conclusion: This project identified data-driven interventions that quality of care for HCC could be improved. The electronic cancer-care tracking system improved timeliness of HCC diagnosis and treatment, which suggest that this system may be useful for improving HCC care coordination and delivery. We also found that external patients discussed at MDLTB showed delayed timeliness of care and underwent more unnecessary (and often invasive) diagnostic procedures than internal patients. Our results suggest that these differences may be improved for external patients if community providers would immediately refer patients for MDLTB discussion and care upon first suspicion of HCC. A fluid external referral process, similar to that of internal patients, may limit unnecessary diagnostic procedures and result in improved timeliness of care and decreased healthcare costs for patients and the healthcare community

Thèse en finance des ménages et Evaluation des Actifs

Cette thèse de doctorat comprend trois articles indépendants sur la finance des ménages et l’évaluation des actifs. Les deux premiers articles sont étroitement liés, utilisent des données similaires et étudient le rôle du risque de revenu du travail dans le choix du portefeuille. Le troisième article étudie un modèle de volatilité basé sur le model de Markov-switching multifractal. Le premier article est intitulé "Countercyclical Income Risk and Portfolio Choices" (avec Sylvain Catherine et Paolo Sodini). En utilisant les données du panel administratif suédois sur les salaires et les choix de portefeuille des particuliers, nous montrons que le risque de du revenu contracyclique réduit la volonté des ménages d'investir sur le marché financier. Le deuxième article est intitulé "Seeking Skewness". À l'aide de données administratives détaillées des ménages suédois sur les portefeuille et le revenu du travail, cet article examine le comportement des investisseurs de la demande d'asymétrie dans leur choix de portefeuille. Le troisième article est "Multifractal Volatility with Shot-noise Component" (avec Laurent Calvet). Baser sur le modèle Markov Switching Multifractal (MSM) de Calvet et Fisher (2004), nous développons dans cet article un modèle de volatilité multifractale à temps discret pour capturer des sauts et des décroissances dans le processus de volatilité.This doctoral thesis consists of three independent papers in household finance and empirical asset pricing. The first two papers are closedly related, use similar data, and investigate the role of labor income risk in portfolio choice. The third paper studies volatility model based on Markov switching multifractal. The first paper is “Countercyclical Income Risk and Portfolio Choices” (with Sylvain Catherine and Paolo Sodini). Using Swedish administrative panel data on individual's wages and portfolio holdings, we show that countercyclical labor income downside risk reduces households' willingness to invest in financial market. The second paper is “Seeking Skewness”. Using detailed disaggregated Swedish household administrative data on portfolio holdings and labor income, this paper investigates retail investors’ behavior of seeking skewness in their portfolio choice. The third paper is “Multifractal Volatility with Shot-noise Component” (with Laurent Calvet). Based on the Markov Switching Multifractal (MSM) model of Calvet and Fisher (2004), we develop in this paper a discrete-time multifractal volatility model to capture the jump and decay pattern in the volatility process along with other stylized facts

Inferring 3D Residue Contacts of Protein Complexes From Evolutionary Sequence Variations

Protein-protein interaction is critical for the biological functions of living organisms. Experimental screens and structural biology have provided detailed insight into the interactions of many protein complexes, but most interactions are still unknown. A rich source of information for protein interactions is the evolutionary sequence record. Analysis of correlated evolutionary sequence changes across proteins had identified residues in close spatial proximity of each other with sufficient accuracy to determine the three-dimensional (3D) structure of protein monomers. In this study, we applied coevolution analysis to predict 3D residue contacts between proteins within complexes of self-associating Escherichia coli CTP synthetase and Thermotoga maritima MreB. Coevolution analysis did not robustly predict inter-protein residue contacts for either protein complexes. From additional analyses, we believe that this low prediction yield was not due to lack of conservation of the protein-protein interaction interface. Thus, further study is required to improve the analysis for the robust prediction of protein-protein contacts