Few-femtosecond Electron Beam with THz-frequency Wakefield-driven Compression

We propose and demonstrate a novel method to produce few-femtosecond electron beam with relatively low timing jitter. In this method a relativistic electron beam is compressed from about 150 fs (rms) to about 7 fs (rms, upper limit) with the wakefield at THz frequency produced by a leading drive beam in a dielectric tube. By imprinting the energy chirp in a passive way, we demonstrate through laser-driven THz streaking technique that no additional timing jitter with respect to an external laser is introduced in this bunch compression process, a prominent advantage over the conventional method using radio-frequency bunchers. We expect that this passive bunching technique may enable new opportunities in many ultrashort-beam based advanced applications such as ultrafast electron diffraction and plasma wakefield acceleration.Comment: 5 pages, 4 figure

Biochemical characterization of a thermostable DNA ligase from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5

International audienc

The mechanical properties of Polyvinyl Butyral (PVB) at high strain rates

Polyvinyl Butyral (PVB) has been largely used as an interlayer material for laminated glass to mitigate the hazard from shattered glass fragments, due to its excellent ductility and adhesive property with glass pane. With increasing threats from terrorist bombing and debris impact, the application of PVB laminated safety glass has been extended from quasi-static loading to impact and blast loading regimes, which has led to the requirement for a better understanding of PVB material properties at high strain rates. In this study, the mechanical properties of PVB are investigated experimentally over a wide range of strain rates. Firstly, quasi-static tensile tests is performed using conventional hydraulic machine at strain rates of 0.008–0.317 s−1. Then high-speed tensile test is carried out using a high-speed servo-hydraulic testing machine at strain rates from 8.7 s−1 to 1360 s−1. It is found that under quasi-static tensile loading, PVB behaves as a hyperelastic material and material property is influenced by loading rate. Under dynamic loading the response of PVB is characterized by a time-dependent nonlinear elastic behavior. The ductility of PVB reduces as strain rate increases. The testing results are consistent with available testing data on PVB material at various strain rates. Analysis is made on the testing data to form strain-rate dependent stress–strain curves of PVB under tension

Combination Analysis of a Radiomics-Based Predictive Model With Clinical Indicators for the Preoperative Assessment of Histological Grade in Endometrial Carcinoma

BackgroundHistological grade is one of the most important prognostic factors of endometrial carcinoma (EC) and when selecting preoperative treatment methods, conducting accurate preoperative grading is of great significance.PurposeTo develop a magnetic resonance imaging (MRI) radiomics-based nomogram for discriminating histological grades 1 and 2 (G1 and G2) from grade 3 (G3) EC.MethodsThis was a retrospective study included 358 patients with histologically graded EC, stratified as 250 patients in a training cohort and 108 patients in a test cohort. T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI) and a dynamic contrast-enhanced three-dimensional volumetric interpolated breath-hold examination (3D-VIBE) were performed via 1.5-Tesla MRI. To establish ModelADC, the region of interest was manually outlined on the EC in an apparent diffusion coefficient (ADC) map. To establish the radiomic model (ModelR), EC was manually segmented by two independent radiologists and radiomic features were extracted. The Radscore was calculated based on the least absolute shrinkage and selection operator regression. We combined the Radscore with carbohydrate antigen 125 (CA125) and body mass index (BMI) to construct a mixed model (ModelM) and develop the predictive nomogram. Receiver operator characteristic (ROC) and calibration curves were assessed to verify the prediction ability and the degree of consistency, respectively.ResultsAll three models showed some amount of predictive ability. Using ADC alone to predict the histological risk of EC was limited in both the cohort [area under the curve (AUC), 0.715; 95% confidence interval (CI), 0.6509–0.7792] and test cohorts (AUC, 0.621; 95% CI, 0.515–0.726). In comparison with ModelADC, the discrimination ability of ModelR showed improvement (Delong test, P < 0.0001 for both the training and test cohorts). ModelM, established based on the combination of radiomic and clinical indicators, showed the best level of predictive ability in both the training (AUC, 0.925; 95% CI, 0.898–0.951) and test cohorts (AUC, 0.915; 95% CI, 0.863–0.968). Calibration curves suggested a good fit for probability (Hosmer–Lemeshow test, P = 0.673 and P = 0.804 for the training and test cohorts, respectively).ConclusionThe described radiomics-based nomogram can be used to predict EC histological classification preoperatively

SOX7 inhibits tumor progression of glioblastoma and is regulated by miRNA-24

Sex-determining region Y-box 7 (SOX7) is a putative tumor suppressor in various types of human cancers. In the present study, the expression and function of SOX7 was investigated in human glioblastoma (GBM) cells

A meta-analysis of adiponectin gene rs22411766 T>G polymorphism and ischemic stroke susceptibility

Several studies have investigated the correlation between adiponectin gene rs22411766 T>G polymorphism and ischemic stroke risk. However, the results were not conclusive with each other. Therefore, to overcome this obstacle, we performed this meta-analysis to further explicate the adiponectin gene rs22411766 T>G polymorphism and ischemic stroke susceptibility. Case-control or cohort studies focused on adiponectin gene rs22411766 T>G polymorphism and ischemic stroke risk were electronic searched in the databases of Medline, Pubmed, Cochrane library, Excerpta Medica database(EMBASE) and China National Knowledge Infrastructure (CNKI). All the potentially relevant studies were included in this meta-analysis. The association between adiponectin gene rs22411766 T>G polymorphism and ischemic stroke was expressed by odds ratio with its confidence interval. Publication bias has been assessed by begg’s funnel plot. All the analyses have been performed by Revman 5.1 statistical software. Finally, a total of six studies with 1,345 cases and 1,421 controls were included in this meta-analysis. Our results demonstrated that there was a significant association between adiponectin gene rs22411766 T>G polymorphism and ischemic stroke risk (p<0.05). People with G single nucleotide of adiponectin gene have the increased risk of developing ischemic stroke compared to T single nucleotide

Statistical analysis for masked hybrid system lifetime data in step-stress partially accelerated life test with progressive hybrid censoring

<div><p>In this paper, we investigate a step-stress partially accelerated lifetime test for the four-component hybrid systems with Type-II progressive hybrid censoring scheme while the life time of system component follows exponential failure rate. In many cases, the exact component causing the system failure cannot be identified and the cause of failure is masked. Based on Type-II progressively hybrid censored and masked data, the maximum likelihood estimations for unknown parameters and acceleration factor are obtained. In addition, approximate confidence interval and bootstrap confidence interval are presented by using the asymptotic distributions of the maximum likelihood estimations for unknown parameters and bootstrap method, respectively. Finally, the proposed method is illustrated through the simulation studies.</p></div

A new method for progressive collapse analysis of RC frames under blast loading

The progressive collapse of structures under blast loading has attracted great attention all over the world. Some guidelines give specific procedures to analyse the progressive collapse of building structures. Numerical analysis and laboratory test results of the progressive collapse of structures have also been reported in the literature. Because the progressive collapse of a structure induced by blast loading occurs only after the blast-loading phase, most of these studies and guideline procedures perform progressive analysis by removing one or a few load-carrying structural members with static and zero initial conditions. The damage on adjacent structural members that might be induced by blast loads and the inevitable non-zero initial conditions when progressive collapse initiates are neglected. These simplifications may lead to inaccurate predictions of the structural collapse process. In this paper, a new method for progressive collapse analysis of reinforced concrete (RC) frame structures by considering non-zero initial conditions and initial damage to adjacent structural members under blast loading is proposed. A three-storey two-span RC frame is used as an example to demonstrate the proposed method. Numerical results are compared with those obtained using the alternative load path method, and with those from comprehensive numerical simulations by directly applying the blast loads on the frame. It is found that the proposed method with a minor and straightforward extension of the simplified 'member-removal' procedure is efficient and reliable in simulating the progressive collapse process of RC frame structures. It requires substantially less computational effort as compared to direct numerical simulations, and gives more accurate predictions of the structural progressive collapse process than the 'member-removal' approach