Observational properties of rigidly rotating dust configurations

We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust (i.e. non interacting particles). We ask the question whether such solutions can describe astrophysical rotating dark matter clouds near the center of galaxies and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks made of ordinary baryonic matter in this space-time has several differences with respect to the emission of light from similar accretion disks around black holes. The shape of the iron K$\alpha$ line in the reflection spectrum of accretion disks can potentially distinguish this class of solution from the Kerr metric, but this may not be possible with current X-ray missions.Comment: 8 pages, 5 figures, to appear in EPJ

Coverage Analysis of Single-swarm mmWave UAV Networks under Multiple Types of Blockages

Millimeter wave (mmWave)-based unmanned aerial vehicle (UAV) communication is susceptible to blockages, even from humans. Previous studies that primarily focused only on static blockage may not accurately characterize the system performance. This paper investigates the coverage performance of mmWave UAV networks by jointly considering multiple types of blockages under finite homogeneous Poisson point process and Binomial point process, which are commonly employed in finite area scenarios with random and fixed number of UAVs, respectively. Particularly, we derive the average line-of-sight probability and coverage probability under static, dynamic, and self blockages. Simulations verify our theoretical results, demonstrating that: the above system performance predominantly depends on self-blockage if UAVs are at high altitudes. Conversely, at relatively low altitudes, all three types of blockages impact them, with static blockage being the dominant factor. To avoid self-blockage, UAV height should satisfy h > hR+ri/tan φb, where hR is the height of the user equipment (UE), ri is the two-dimensional distance of the UAV-UE link, φb is the elevation angle between UE and UAV. The required height is proportional to ri and increases as distance d between the user and UE decreases, as φb is proportional to d. The findings help on designing the network parameters. To our best knowledge, this is the first work to analyze the coverage of mmWave UAV networks under multiple types of blockages

Clinical Characteristics of 26 Human Cases of Highly Pathogenic Avian Influenza A (H5N1) Virus Infection in China

BACKGROUND: While human cases of highly pathogenic avian influenza A (H5N1) virus infection continue to increase globally, available clinical data on H5N1 cases are limited. We conducted a retrospective study of 26 confirmed human H5N1 cases identified through surveillance in China from October 2005 through April 2008. METHODOLOGY/PRINCIPAL FINDINGS: Data were collected from hospital medical records of H5N1 cases and analyzed. The median age was 29 years (range 6-62) and 58% were female. Many H5N1 cases reported fever (92%) and cough (58%) at illness onset, and had lower respiratory findings of tachypnea and dyspnea at admission. All cases progressed rapidly to bilateral pneumonia. Clinical complications included acute respiratory distress syndrome (ARDS, 81%), cardiac failure (50%), elevated aminotransaminases (43%), and renal dysfunction (17%). Fatal cases had a lower median nadir platelet count (64.5 x 10(9) cells/L vs 93.0 x 10(9) cells/L, p = 0.02), higher median peak lactic dehydrogenase (LDH) level (1982.5 U/L vs 1230.0 U/L, p = 0.001), higher percentage of ARDS (94% [n = 16] vs 56% [n = 5], p = 0.034) and more frequent cardiac failure (71% [n = 12] vs 11% [n = 1], p = 0.011) than nonfatal cases. A higher proportion of patients who received antiviral drugs survived compared to untreated (67% [8/12] vs 7% [1/14], p = 0.003). CONCLUSIONS/SIGNIFICANCE: The clinical course of Chinese H5N1 cases is characterized by fever and cough initially, with rapid progression to lower respiratory disease. Decreased platelet count, elevated LDH level, ARDS and cardiac failure were associated with fatal outcomes. Clinical management of H5N1 cases should be standardized in China to include early antiviral treatment for suspected H5N1 cases

Study on the Conservation Planning of Vernacular Landscape in Village Planning in the Context of Multi-regulation Integration——The Case of Changlong Village in Pinggui District, Hezhou City

As one of the important concentrated manifestations of Chinese rural culture, vernacular landscape is related to the success or failure of new rural construction and village planning. How to protect the existing vernacular landscape in the practical village planning advocated by “multi-planning” and how to play the role of vernacular landscape in supporting development and protecting cultural heritage is one of the important tasks of village planning. This paper takes Changlong Village in Pinggui District, Hezhou City, Guangxi Province, as an example to explore and study the issue of planning the native landscape of Changlong Village in the multi-planning village planning, so as to provide technical support for the scientific protection and reasonable development and utilization of the native landscape for rural revitalization, and to provide reference and reference for the native landscape planning in the village planning of similar areas in China

Effect of Post-Deposition Annealing on the Structural Evolution and Optoelectronic Properties of In₂O₃:H Thin Films

An infrared transparent conductive material is a solution to realize the shielding function of infrared windows against electromagnetic waves, by combining the two characteristics of high transmission and conductivity in infrared wavelengths. Indium-hydroxide-doped (In2O3:H) thin films were prepared by atomic layer deposition method, which can achieve high IR transmission by reducing the carrier concentration on the basis of ensuring the electrical properties. On this basis, the effect of the post-deposition annealing process on the microstructure evolution and optoelectronic properties of In2O3:H thin films was investigated in this paper. It is demonstrated that the carrier mobility after annealing is up to 90 cm2/(V·s), and the transmittance at the 4 μm is about 70%, meanwhile, the carrier concentration after annealing in air atmosphere is reduced to 1019 cm−3, with a transmission rate of up to 83% at 4 μm. The simulations visualize the shielding performance of the annealed In2O3:H thin film against radar electromagnetic waves. It provides a guideline for fabricating lightweight, thin, and multi-functional shielding infrared transparent materials in the key fields of spacecraft and high precision electronics

Studying the influence of aerosol types on solar radiation prediction

The influence of aerosol types on Solar radiation prediction was studied in this paper. According to Chinese population density, China administration districts were divided into areas with urban aerosol type and rural aerosol type based on Arcgis. The Solar radiation all over China was simulated by the Mesoscale numerical Weather Prediction Model (WRF). The forecasting was compared with the data of “Clouds and the Earth’s Radiant Energy System” released by NASA. The results showed that there was a big improvement when the different aerosol types in different areas were taken into consideration

Low-carbon generation expansion planning considering uncertainty of renewable energy at multi-time scales

With the development of carbon electricity, achieving a low-carbon economy has become a prevailing and inevitable trend. Improving low-carbon expansion generation planning is critical for carbon emission mitigation and a low- carbon economy. In this paper, a two-layer low-carbon expansion generation planning approach considering the uncertainty of renewable energy at multiple time scales is proposed. First, renewable energy sequences considering the uncertainty in multiple time scales are generated based on the Copula function and the probability distribution of renewable energy. Second, a two-layer generation planning model considering carbon trading and carbon capture technology is established. Specifically, the upper layer model optimizes the investment decision considering the uncertainty at a monthly scale, and the lower layer one optimizes the scheduling considering the peak shaving at an hourly scale and the flexibility at a 15-minute scale. Finally, the results of different influence factors on low-carbon generation expansion planning are compared in a provincial power grid, which demonstrate the effectiveness of the proposed model

Positive Emotion and Media Dependence: Measuring Risk Information Seeking and Perception in the COVID-19 Pandemic Prevention

Risk perception and information seeking behaviors are affected by individual psychological and situational factors. In the background of COVID-19 prevailing for a long period, this study examined Chinese people’s information seeking and processing behavior by the RISP model, which focused on the impact of individual risk perception, affective response, perceived information-gathering capacity, and media trust and the impact of the above factors on information seeking. This study designed an online survey with gender and age quotas among the Chinese population, including a total of 675 valid samples. It was found that the Chinese public’s risk perception to pandemic had a positive effect on perceived information-gathering capacity and media trust. Furthermore, both positive emotional responses and negative emotional responses had a positive effect on information seeking behavior. Nurturing positive emotion engendered a holistic perception in pandemic information seeking. In addition, media trust, perceived information-gathering capacity, and subjective norms also positively impact information seeking behavior