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The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
Karlsruhe Institute of Technology (KIT) is doing research and development in the field of megawatt-class radio frequency (RF) sources (gyrotrons) for the Electron Cyclotron Resonance Heating (ECRH) systems of the International Thermonuclear Experimental Reactor (ITER) and the DEMOnstration Fusion Power Plant that will follow ITER. In the focus is the development and verification of the European coaxial-cavity gyrotron technology which shall lead to gyrotrons operating at an RF output power significantly larger than 1 MW CW and at an operating frequency above 200 GHz. A major step into that direction is the final verification of the European 170 GHz 2 MW coaxial-cavity pre-prototype at longer pulses up to 1 s. It bases on the upgrade of an already existing highly modular short-pulse (ms-range) pre-prototype. That pre-prototype has shown a world record output power of 2.2 MW already. This paper summarizes briefly the already achieved experimental results using the short-pulse pre-prototype and discusses in detail the design and manufacturing process of the upgrade of the pre-prototype toward longer pulses up to 1 s.
Varicella–zoster virus (VZV) infection (chickenpox) results in latency and subsequent reactivation manifests as shingles. Effective attenuated vaccines (vOka) are available for prevention of both illnesses. In this study, an amplicon-based sequencing method capable of differentiating between VZV wild-type (wt) strains and vOka vaccine is described. A total of 44 vesicular fluid specimens collected from 43 patients (16 from China and 27 from the UK) with either chickenpox or shingles were investigated, of which 10 had received previous vaccination. Four sets of polymerase chain reactions were set up simultaneously with primers amplifying regions encompassing four single nucleotide polymorphisms (SNPs), ‘69349-106262-107252-108111’. Nucleotide sequences were generated by Sanger sequencing. All samples except one had a wt SNP profile of ‘A-T-T-T’. The sample collected from a patient who received vaccine 7–10 days ago, along with VZV vaccine preparations, Zostavax and Baike-varicella gave a SNP profile ‘G-C-C-C’. The results show that this method can distinguish vaccine-derived virus from wt viruses from main four clades, (clades 1–4) and should be of utility worldwide.
Rural-to-urban migrant workers are a large marginalised population in urban China. Prevalence estimates of common mental health problems (CMHPs) in previous studies varied widely and very few studies have investigated migration-related factors of CMHPs in migrant workers. The objective of this study was to determine the prevalence and risk factors of CMHPs among Chinese migrant workers.
A random sample of 3031 migrant workers of ten manufacturing factories in Shenzhen, China, completed a standardised questionnaire containing socio-demographic and migration-related variables and the Chinese 12-item General Health Questionnaire (GHQ-12). A GHQ-12 score of three or higher was used to denote the presence of CMHPs.
The prevalence of CMHPs was 34.4% in Chinese migrant workers. In multiple logistic regression, risk factors for CMHPs included being 16–25 years old (odd ratio [OR] 1.65, 95% confidence interval [CI] 1.28, 2.12), being 26–35 years old (OR 1.36, 95% CI: 1.05, 1.75), low monthly income (OR 1.42, 95% CI 1.04, 1.92), poor living condition (OR: 1.76, 95% CI: 1.22, 2.54), physical illness in the past 2 weeks (OR 1.72, 95% CI 1.43, 2.05), having worked in many cities (OR 1.34, 95% CI 1.03, 1.74), infrequently visiting hometown (OR 1.56, 95% CI 1.22, 1.99), poor Mandarin proficiency (OR 1.51, 95%CI 1.13, 2.01), a low level of perceived benefits of migration (OR 1.33, 95% CI 1.14, 1.55) and working more than 8 h/day (OR 1.39, 95% CI 1.14, 1.70).
CMHPs are very prevalent among Chinese migrant workers. Given the large number of Chinese migrant workers, there is an urgent need to address the mental health burden of China's migrant worker population.
Historically, alloy development with better radiation performance has been focused on traditional alloys with one or two principal element(s) and minor alloying elements, where enhanced radiation resistance depends on microstructural or nanoscale features to mitigate displacement damage. In sharp contrast to traditional alloys, recent advances of single-phase concentrated solid solution alloys (SP-CSAs) have opened up new frontiers in materials research. In these alloys, a random arrangement of multiple elemental species on a crystalline lattice results in disordered local chemical environments and unique site-to-site lattice distortions. Based on closely integrated computational and experimental studies using a novel set of SP-CSAs in a face-centered cubic structure, we have explicitly demonstrated that increasing chemical disorder can lead to a substantial reduction in electron mean free paths, as well as electrical and thermal conductivity, which results in slower heat dissipation in SP-CSAs. The chemical disorder also has a significant impact on defect evolution under ion irradiation. Considerable improvement in radiation resistance is observed with increasing chemical disorder at electronic and atomic levels. The insights into defect dynamics may provide a basis for understanding elemental effects on evolution of radiation damage in irradiated materials and may inspire new design principles of radiation-tolerant structural alloys for advanced energy systems.
The scope of scientific interests of about 130 Commission members is much more complex than one may expect from the title of the commission. Besides traditional topics like the compilation of astrometric catalogues and the construction of an inertial reference system, more and more investigations performed by our members have been dedicated to the astrophysical interpretation of observations including among others astrometric data.
A pulsar timing system has been set up using the 25-m Nanshan telescope of the Urumqi Astronomical Observatory. It uses a dual polarization receiver operating at 18 cm and a filterbank receiver. The data acquisition system is based on a PC using the Windows NT operating system. Timing properties of about 100 pulsars will be monitored with this system.
We present new multiband photometric results for ROTSE-I δ Sct stars and the Fourier decomposition analysis. Our result shows that most of the stars classified as ROTSE-I δ Sct stars seem to be W UMa type eclipsing variable stars.
The vertical TiO2 nanotube arrays constituting the core of 3-D nanoscale electrode architecture were synthesized over Ti sheet by anodization. Such formed TiO2 nanotubes are electrically conducting and amorphous as confirmed by XRD studies. Nanotube morphology is affected by water content and in the present study, close-packed 3-4 μm long TiO2 nanotube arrays of 45-50 nm diameter are formed with 2% water as revealed by the transmission and scanning electron microscopy. The redox active polypyrrole sheath is created by ultra-short pulsed current electropolymerization. Electrochemical properties of the 3-D nanoscaled TiO2 nanotube core-polypyrrole sheath electrodes relevant to the energy storage were investigated using cyclic voltammetry (CV) plots, electrochemical impedance spectroscopy (EIS), Charge discharge (CD) tests. High areal capacitance density of 48 mF cm-2 and low charge transfer resistance 12 Ω cm-2 with least ion diffusion limitation are realized at optimized polypyrrole sheath thickness. The Raman spectra studies reveal anion at specific chain locations involve in the redox process.
Crop nitrogen (N) status is an important indicator of crop health and predictor of subsequent crop yield. The present study was conducted to analyse the relationships between nitrogen nutrition index (NNI), nitrogen biomass difference (ΔNB) and spectral indices in wheat, and then attempt to improve field N management. Spectral indices and concurrent sample N and biomass parameters were obtained from the Shihezi University experimental site in Xinjiang, China during 2009 and 2010. The results showed that all spectral indices were significantly correlated with NNI. Regression functions with the highest determination coefficient (R2) and the lowest root mean square error (RMSE) were used to improve prediction of NNI, and then the selected spectral index was used to estimate NNI and ΔNB. The strongest relationships were observed for the products of modified normalized difference 705 × biomass dry weight (BND705) and the enhanced vegetation index 2 (EVI2) for estimating NNI. There were also strong relationships between the NNI and the normalized NNI (ΔNNI) as well as between ΔNNI and ΔNB, with a linear relationship between ΔNB and the spectral index BND705 and a linear relationship between ΔNB and the spectral index EVI2. These results indicated that BND705 and EVI2 can be used to improve the accuracy of NNI estimation, and the correlations of ΔNB and NNI with BND705 and EVI2 can be used to further improve field N management in wheat.
The BiFeO3 (BFO) / PbTiO3 (PT) multiferroic ceramic composites with multilayered structure were prepared from orderly laminated BFO and PT tapes by tape casting method. The dielectric constant εr, loss tanδ, remnant polarization Pr and field-induced strain of BFO/PT ceramic composites were 140 (1 kHz), 5% (1 kHz), 12 µC/cm2 (at 80 kV/cm) and 0.06% (at 80 kV/cm) respectively, which were comparable to those pure BFO ceramics and BFO-based solid solutions
Despite the strong increase in observational data on extrasolar planets, the processes that led to the formation of these planets are still not well understood. However, thanks to the high number of extrasolar planets that have been discovered, it is now possible to look at the planets as a population that puts statistical constraints on theoretical formation models. A method that uses these constraints is planetary population synthesis where synthetic planetary populations are generated and compared to the actual population. The key element of the population synthesis method is a global model of planet formation and evolution. These models directly predict observable planetary properties based on properties of the natal protoplanetary disc, linking two important classes of astrophysical objects. To do so, global models build on the simplified results of many specialized models that address one specific physical mechanism. We thoroughly review the physics of the sub-models included in global formation models. The sub-models can be classified as models describing the protoplanetary disc (of gas and solids), those that describe one (proto)planet (its solid core, gaseous envelope and atmosphere), and finally those that describe the interactions (orbital migration and N-body interaction). We compare the approaches taken in different global models, discuss the links between specialized and global models, and identify physical processes that require improved descriptions in future work. We then shortly address important results of planetary population synthesis like the planetary mass function or the mass–radius relationship. With these statistical results, the global effects of physical mechanisms occurring during planet formation and evolution become apparent, and specialized models describing them can be put to the observational test. Owing to their nature as meta models, global models depend on the results of specialized models, and therefore on the development of the field of planet formation theory as a whole. Because there are important uncertainties in this theory, it is likely that the global models will in future undergo significant modifications. Despite these limitations, global models can already now yield many testable predictions. With future global models addressing the geophysical characteristics of the synthetic planets, it should eventually become possible to make predictions about the habitability of planets based on their formation and evolution.
In order to make use of the waste heat caused by the unabsorbed light based on photovoltaic(PV) effect, a novel hybrid dye-sensitized solar cells (DSSC) with the synergies of PV and thermoelectric(TE) effect has been proposed in present work. The main idea is to prepare a composite hybrid DSSC photoanode which can simultaneously achieve PV and TE conversion by incorporating the excellent TE Bi-Te alloys into TiO2 nanomaterial. In this paper, Bi2Te3 nanoplates with different size were doped in the TiO2 nanoparticle photoanode and the effect of the Bi2Te3 size on the properties of DSSCs was analyzed. It is found that with the decrease of the size of the Bi2Te3 nanoplates, the TE performance became better and the dye absorption and the conversion efficiency of DSSCs were improved. Preliminary results show that the efficiency of DSSC with Bi2Te3 increased atleast 15.3% compared to the undoped. By further optimizing the parameters, the performance of DSSC is estimated to have a much more enhancement. Therefore, the way of combination PV and TE provides an alternative way to improve the performance of DSSC.
For structural investigation, highly (112) oriented tetragonal Cu2ZnSnS4 (CZTS) thin films on hexagonal sapphire (0001) single crystal substrates were obtained by radio frequency (RF) magnetron sputtering. The influences of the deposition parameters, such as substrate temperature (Tsub) and working Ar pressure (PAr) on the chemical composition and structural properties of as deposited CZTS films were investigated. The film sputtered at 500°C has the only orientation of (112), also, it bears the best structural quality with pure CZTS phase and an estimated band gap of 1.51eV.
Water-splitting by using electric power produced by solar cells is promising system to produce hydrogen without fossil fuels. Oxygen evolving catalyst is, however, major problem to prevent using this system widely because precious materials are used in the catalyst. Considering from the photosynthesis II of plants, the compound of Ca-Mn-O is one of the candidates for the oxygen evolving catalyst. In this study, the synthesis condition and the oxygen evolving electrocatalytic activity of CaMn2O4•xH2O are investigated. The overpotential at 0.1 mA/cm2 was 0.28 V when using the electrode of carbon paste and CaMn2O4•H2O with the weight ratio of 3:1.