Split Hopkinson Pressure Bar Graphical Analysis Tool

An open-source Split Hopkinson Pressure Bar graphical data analysis tool has been developed. Written in Matlab®, the code can be freely distributed either as an executable binary or editable Matlab files. Beginning with raw voltages from two strain gages along with the incident/transmitted bars’ mechanical and geometrical properties, the user can visually analyze forces and displacements at the bar faces and the stresses and strains in the specimen. Wave dispersion and modulus correction are available in this package. A modest documentation and video tutorials accompany the software.     

Transient dynamic analysis of interface cracks in anisotropic bimaterials by the scaled boundary finite-element method

The transient response of finite bimaterial plates with interface cracks is analyzed directly in the time domain by using the scaled boundary finite-element method. A bimaterial plate is divided into a few subdomains. Only the boundaries of the subdomains are discretized with line elements leading to great flexibility in mesh generation. The displacement and stress fields are expressed as a series solution which separates the singular stress term from other high-order terms. The oscillatory stress singularity in the radial direction emanating from the scaling center is represented analytically. The complex dynamic stress intensity factors are evaluated directly from either the stresses or the crack opening displacements of the singular stress term. Numerical examples of cracked anisotropic bimaterial plates are presented to verify the accuracy of the present technique and to provide additions to the very limited number of reference solutions in the literature.     

Radiography of Earth's core and mantle with atmospheric neutrinos

A measurement of the absorption of neutrinos with energies in excess of 10 TeV when traversing the Earth is capable of revealing its density distribution. Unfortunately, the existence of beams with sufficient luminosity for the task has been ruled out by the AMANDA South Pole neutrino telescope. In this Letter we point out that, with the advent of second-generation kilometer-scale neutrino detectors, the idea of studying the internal structure of Earth may be revived using atmospheric neutrinos instead.     

Primary ion fluence dependence in time-of-flight SIMS of self-assembled monolayer of alkyl thiol molecules on Au(1 1 1)—Discussion of static limit

The nondestructive nature of static secondary ion mass spectrometry (SIMS) in the context of studies of self-assembled monolayers (SAMs) of organic molecules has been examined by measuring the primary ion fluence dependence of secondary ion signals with two well-known SAMs, C₁₈H₃₇SH on Au(1 1 1) and C₁₈H₃₇PO₃H₂ on freshly cleaved mica. This SIMS analysis is challenging because the bonding nature is delicate and the areal molecular density is less than 10¹⁵ cm⁻². In SIMS, it is prevalently assumed that if the primary ion fluence is confined to not more than 1 × 10¹² cm⁻², all secondary ion signals should not change by more than 10% and the practically defined static condition is satisfied. Our results from time-of-flight SIMS with the common primary ions of Bi₃⁺, Bi⁺ and Ar⁺, indicate that this prevalent static assumption fails for both model SAMs. The SIMS results from the phosphyl case, which have been recently published, consistently display the evidence of bombardment-induced damage. In comparison, the thiol case presented here shows much more complex primary ion fluence dependence of SIMS signals. It is therefore concluded that practical static analysis should use primary ion fluence not more than 1 × 10¹¹ cm⁻² or should simply record and report the effects of primary ion fluence.     

Automated Computational Detection of Disease Activity in ANCA-Associated Glomerulonephritis Using Raman Spectroscopy: A Pilot Study

Biospectroscopy offers the ability to simultaneously identify key biochemical changes in tissue associated with a given pathological state to facilitate biomarker extraction and automated detection of key lesions. Herein, we evaluated the application of machine learning in conjunction with Raman spectroscopy as an innovative low-cost technique for the automated computational detection of disease activity in anti-neutrophil cytoplasmic autoantibody (ANCA)-associated glomerulonephritis (AAGN). Consecutive patients with active AAGN and those in disease remission were recruited from a single UK centre. In those with active disease, renal biopsy samples were collected together with a paired urine sample. Urine samples were collected immediately prior to biopsy. Amongst those in remission at the time of recruitment, archived renal tissue samples representative of biopsies taken during an active disease period were obtained. In total, twenty-eight tissue samples were included in the analysis. Following supervised classification according to recorded histological data, spectral data from unstained tissue samples were able to discriminate disease activity with a high degree of accuracy on blind predictive modelling: F-score 95% for >25% interstitial fibrosis and tubular atrophy (sensitivity 100%, specificity 90%, area under ROC 0.98), 100% for necrotising glomerular lesions (sensitivity 100%, specificity 100%, area under ROC 1) and 100% for interstitial infiltrate (sensitivity 100%, specificity 100%, area under ROC 0.97). Corresponding spectrochemical changes in paired urine samples were limited. Future larger study is required, inclusive of assigned variables according to novel non-invasive biomarkers as well as the application of forward feature extraction algorithms to predict clinical outcomes based on spectral features.     

Detection and quantification of multiple molecular species in mainstream cigarette smoke by continuous-wave terahertz spectroscopy

Continuous-wave terahertz spectroscopy by photomixing is applied to the analysis of mainstream cigarette smoke. Using the wide tunability of the source, spectral signatures of hydrogen cyanide (HCN), carbon monoxide (CO), formaldehyde (H2CO), and water (H2O) have been observed from 500 to 2400 GHz. The fine spectral purity allows direct concentration measurement from the pure rotational transitions of HCN and CO. The quantification of the measurement was validated by the means of a calibration gas containing CO. The potential of this technique for trace gas detection is demonstrated with an estimated detection limit of HCN equal to 9 parts in 10(6).     

40 Gbit/s传输技术的测试及挑战

1 前言 尽管40 Gbit/s传输技术在十多年前就出现了,但一直处于实验状态.随着电信行业的不断复苏,40 Gbit/s传输技术的研究取得了可喜的进展.第一个40 Gbil/s商用系统于2005年成功部署,运营商已逐渐认识到这种技术的显著优势,市场对这种技术的需求在稳步增长.     

Social media use and university students’ participation in a large-scale protest campaign: The case of Hong Kong’s Umbrella Movement

This study examines the impact of social media use on participation in large-scale protest campaigns that feature a range of participation opportunities. It develops a theoretical model which distinguishes between support generation and behavior activation effects, differentiates collective action, digital, and personalized action participation, and posits social media use as a mediator between social psychological predictors of protest behavior and actual participation. The empirical analysis focuses on Hong Kong’s Umbrella Movement in 2014. Analyzing a probability sample of university students (N = 795), the findings show that sharing political information and direct connections with political actors via social media have significant impact on both support for and participation in the Umbrella Movement. Social media use has effects on each dependent variable in the causal chain even after all the immediate causes are controlled. Social media use also mediates part of the impact of general political awareness, efficacy, and grievances on movement support and participation.