Exploring the low redshift universe: two parametric models for effective pressure

Astrophysical observations have put unprecedentedly tight constraints on cosmological theories. The $\Lambda$CDM model, mathematically simple and fits observational data-sets well, is preferred for explaining the behavior of universe. But many basic features of the dark sectors are still unknown, which leaves rooms for various nonstandard cosmological hypotheses. As the pressure of cosmological constant dark energy is unvarying, ignoring contributions from radiation and curvature terms at low redshift, the effective pressure keeps constant. In this paper, we propose two parametric models for non-constant effective pressure in order to study the tiny deviation from $\Lambda$CDM at low redshift. We recover our phenomenological models in the scenarios of quintessence and phantom fields, and explore the behavior of scalar field and potential. We constrain our model parameters with SNe Ia and BAO observations, and detect subtle hints of $\omega_{de}<-1$ from the data fitting results of both models, which indicates possibly a phantom dark energy scenario at present.Comment: 11 pages, 24 figure

Time Reversal Method for Arch Bridge Cables Inspection using Longitudinal Guided Waves

Arch bridge cables consist of anchor heads, steel wires parallel arranged in an equilateral hexagon and hot-extruding PE sheathing layers outside the wires. The complex structure and contact force between wires aggravates the dispersion and attenuation of guided waves in steel wires. In order to reduce the attenuation of acoustical energy, below 80kHz low-frequency longitudinal guided waves is usually adopted. Low-frequency guided waves attenuate more slowly than high-frequency waves, but the received signal packets are wider and less recognizable. In this paper, the process of the time reversal method[1] is presented and the related parameters are calculated. Over a wide frequency range, using narrow-band pulse signals with different center-frequencies to drive comb-like magnetostrictive transducer array round the cable, extract the echo signals, which contains some feature information such as flaws, anchor heads, structural noise caused by contact force between wires. By taking advantage of the time-space compression characteristics of the method, the identification of anchor heads and flaws can be improved effectively and noise can also be decreased by driving the transducers again with the time reversed signal. Verification experiments show that the acoustical energy of guided waves can be focused on the position of flaws and the amplitude of flaws echo waves can be increased. At severe dispersion frequency, time reversal focusing process can improve the signal-noise ratio and suppress dispersion phenomenon caused by structural contact force

Microwave-to-optical conversion using lithium niobate thin-film acoustic resonators

Acoustic or mechanical resonators have emerged as a promising means to mediate efficient microwave-to-optical conversion. Here, we demonstrate conversion of microwaves up to 4.5 GHz in frequency to 1500 nm wavelength light using optomechanical interactions on suspended thin-film lithium niobate. Our method uses an interdigital transducer that drives a freestanding 100 μm-long thin-film acoustic resonator to modulate light traveling in a Mach–Zehnder interferometer or racetrack cavity. The strong microwave-to-acoustic coupling offered by the transducer in conjunction with the strong photoelastic, piezoelectric, and electro-optic effects of lithium niobate allows us to achieve a half-wave voltage of Vπ = 4.6 V and Vπ = 0.77 V for the Mach–Zehnder interferometer and racetrack resonator, respectively. The acousto-optic racetrack cavity exhibits an optomechanical single-photon coupling strength of 1.1 kHz. To highlight the versatility of our system, we also demonstrate a microwave photonic link with unitary gain, which refers to a 0 dB microwave power transmission over an optical channel. Our integrated nanophotonic platform, which leverages the compelling properties of lithium niobate, could help enable efficient conversion between microwave and optical fields

Researching Chinese Students in the UK - the Use of Ethnography in Social Media Studies

The growing prevalence of digital media has led to an increasing number of studies investigating its role in people’s lives. Traditionally, ethnographers go to the fieldsite physically to understand people and their culture. Now, with a large amount of social interaction taking place online, ethnographers have also began attempting to use digital methods to understand people’s online practices, interactions, and cultural production. This paper documents both online and offline ethnographic methods employed in a pilot study that set out to understand the ways that Chinese students portray their lives on social media when studying at UK universities. With a focus on in-depth reflections on methodologies and data collection processes, this paper aims to provide a point of reference for researchers who are interested in doing ethnography in the digital field

Impact of spiritual values on tourists’ psychological wellbeing: evidence from China’s Buddhist mountains

Spiritual values can be a source of meaning for people, and can also determine their feelings, behavior, and mental health. In China’s Buddhist mountains, we collected a total of 400 valid questionnaires from Mount Putuo and Mount Jiuhua, and identified spiritual values as transcendence, general connectedness, inner balance, positive life direction, and special religious feelings. We also explored the impact of these spiritual values on tourists’ psychological wellbeing according to the PERMA model (positive emotion, engagement, relationships, meaning, and achievement). The results revealed that the more easily attained spiritual values (general connectedness, positive life direction, and special religious feelings) had a greater influence on psychological wellbeing than the less easily-attained spiritual values (transcendence and inner balance). Positive emotion and meaning, as components of psychological wellbeing, were strongly influenced by the four spiritual values, whereas engagement, accomplishment, and relationships were influenced by fewer spiritual values. The research contributes to the existing knowledge on spiritual values by analyzing their dimensions and relationships with tourists’ wellbeing from different levels, and also provides empirical suggestions for the sustainable development of religious tourism destinations

Can Teaching Enthusiasm Partially Predict the Reading Attainment of Low-income Students in Secondary Schools in England?

The poverty achievement gap in early reading is a persistent issue in England and around the world, potentially disadvantaging poor students and their further study. This new study employs student-perceived teaching enthusiasm and reading attitudes to help explain the poverty attainment gap. The sample was 5,242 15-year-old participants in PISA 2018 from 175 secondary schools in England. Path analysis is used to investigate the potential effect of teaching enthusiasm on the reading attainment of low-income students. The findings indicate that family socioeconomic status remains an important predictor of students' reading achievement. Students from economically privileged families tend to rate teaching enthusiasm more highly and express a positive reading attitude, which can partially explain the poverty attainment gap in reading. Therefore, teachers might be able to enhance low-income students’ reading outcomes and close the poverty attainment gap a little through enhanced teaching enthusiasm to cultivate students’ positive reading attitudes

Clinical and Epidemiological Investigation of TCM Syndromes of Patients with Coronary Heart Disease in China

To compare the regional differences in TCM syndromes of patients with coronary heart disease (CHD) between North and South China. A total of 624 patients with a diagnosis of CHD, confirmed by coronary angiography, were included in the comparative analysis to determine the occurrence pattern, characteristics of TCM syndrome distribution, and differences in syndrome combinations and major syndrome types (deficiency or excess) between North and South China. The incidence of CHD tended to be higher in North China (54.6%) compared with that in South China (45.4%). The proportions of patients with a qi-deficiency syndrome (83.7%), turbid phlegm syndrome (68.9%), or blood stasis syndrome (91.5%) were generally higher in the South group, while the proportion of patients with a cold congelation syndrome (7.9%) was identified to be obviously higher in the North group (P < 0.01). Moreover, compared with that in the South group, the overall frequency of syndrome combinations tended to be lower in the North group (P < 0.01); and the most common types of TCM syndrome were excess syndrome (193, 56.6%) and primary deficiency and secondary excess syndrome (244, 86.2%) in the North and South groups, respectively (P < 0.01). A regional difference does exist in the TCM syndromes of patients with CHD between North and South China, indicating that the prevention and treatment of CHD in South China should not only focus on promoting blood circulation and removing blood stasis, but also include supplementing qi and eliminating phleg

Energy-resolved Photoconductivity Mapping in a Monolayer-bilayer WSe2 Lateral Heterostructure

Vertical and lateral heterostructures of van der Waals materials provide tremendous flexibility for band structure engineering. Since electronic bands are sensitively affected by defects, strain, and interlayer coupling, the edge and heterojunction of these two-dimensional (2D) systems may exhibit novel physical properties, which can be fully revealed only by spatially resolved probes. Here, we report the spatial mapping of photoconductivity in a monolayer-bilayer WSe2 lateral heterostructure under multiple excitation lasers. As the photon energy increases, the light-induced conductivity detected by microwave impedance microscopy first appears along the hetero-interface and bilayer edge, then along the monolayer edge, inside the bilayer area, and finally in the interior of the monolayer region. The sequential emergence of mobile carriers in different sections of the sample is consistent with the theoretical calculation of local energy gaps. Quantitative analysis of the microscopy and transport data also reveals the linear dependence of photoconductivity on the laser intensity and the influence of interlayer coupling on carrier recombination. Combining theoretical modeling, atomic scale imaging, mesoscale impedance microscopy, and device-level characterization, our work suggests an exciting perspective to control the intrinsic band-gap variation in 2D heterostructures down to the few-nanometer regime.Comment: 18 pages, 5 figures; Nano Lett., Just Accepted Manuscrip