When and Where: Predicting Human Movements Based on Social Spatial-Temporal Events

Predicting both the time and the location of human movements is valuable but challenging for a variety of applications. To address this problem, we propose an approach considering both the periodicity and the sociality of human movements. We first define a new concept, Social Spatial-Temporal Event (SSTE), to represent social interactions among people. For the time prediction, we characterise the temporal dynamics of SSTEs with an ARMA (AutoRegressive Moving Average) model. To dynamically capture the SSTE kinetics, we propose a Kalman Filter based learning algorithm to learn and incrementally update the ARMA model as a new observation becomes available. For the location prediction, we propose a ranking model where the periodicity and the sociality of human movements are simultaneously taken into consideration for improving the prediction accuracy. Extensive experiments conducted on real data sets validate our proposed approach

Multivalent cation crosslinking suppresses highly energetic graphene oxide’s flammability

The authors acknowledges National Science Foundation- Experimental Program to Stimulate Competitive Research (NSF-EPSCoR) for partial support, Prof. S. Yu’s lab for the micro-Raman experiments, and Dr. Jingyi Chen’s lab for the TGA study.Graphene oxide (GO), a common intermediate for making graphene-like materials from graphite, was recently found to possess an explosive fire-hazard that can jeopardize the GO’s large-scale production and wide applications. This work reports a simple and facile method to cross-link the GO with Al3+ cations, in one step, into a freestanding flexible membrane. This inorganic membrane resists in-air burning on an open-flame, at which non-cross-linked GO was burnt out within ~5 seconds. All characterization data suggested that the in-situ “epoxy ring opening” reactions on GO surface facilitated the cross-linking, which elucidated a new mechanism for the generalized inorganic polymerization. With the much improved thermal- and water-stabilities, the cross-linked GO-film can help to advance high-temperature fuel-cells, electronic packaging, etc. as one of the long-sought inorganic polymers known to date.PostprintPeer reviewe

Waiting but not Aging: Optimizing Information Freshness Under the Pull Model

The Age-of-Information is an important metric for investigating the timeliness performance in information-update systems. In this paper, we study the AoI minimization problem under a new Pull model with replication schemes, where a user proactively sends a replicated request to multiple servers to "pull" the information of interest. Interestingly, we find that under this new Pull model, replication schemes capture a novel tradeoff between different values of the AoI across the servers (due to the random updating processes) and different response times across the servers, which can be exploited to minimize the expected AoI at the user's side. Specifically, assuming Poisson updating process for the servers and exponentially distributed response time, we derive a closed-form formula for computing the expected AoI and obtain the optimal number of responses to wait for to minimize the expected AoI. Then, we extend our analysis to the setting where the user aims to maximize the AoI-based utility, which represents the user's satisfaction level with respect to freshness of the received information. Furthermore, we consider a more realistic scenario where the user has no prior knowledge of the system. In this case, we reformulate the utility maximization problem as a stochastic Multi-Armed Bandit problem with side observations and leverage a special linear structure of side observations to design learning algorithms with improved performance guarantees. Finally, we conduct extensive simulations to elucidate our theoretical results and compare the performance of different algorithms. Our findings reveal that under the Pull model, waiting does not necessarily lead to aging; waiting for more than one response can often significantly reduce the AoI and improve the AoI-based utility in most scenarios.Comment: 15 pages. arXiv admin note: substantial text overlap with arXiv:1704.0484

Relaxor-to-ferroelectric crossover and disruption of polar order in "empty" tetragonal tungsten bronzes

JG would like to thank the EPSRC for provision of a studentship via the doctoral training grant (EP/K503162/1). The research data (and/or materials) supporting this publication can be accessed at [http://dx.doi.org/10.17630/a7a9bc13-b5cb-485d-914a-923832f25190]Combined temperature-dependent structural and electrical characterization of a series of “empty” ferroelectric tetragonal tungsten bronzes (TTBs) of composition Ba4(La1- xNdx)0.67□1.33Nb10O30 are reported. The La-material exhibits a temperature dependent crossover from relaxor-ferroelectric to polar (but non-ferroelectric) to linear dielectric behavior. The loss of ferroelectric switching in the polar, non-ferroelectric phase is accompanied by disorder associated with structural relaxation due the significant vacancy concentration at the A1-perovskite-like site. In this disordered regime, large polarization can be re-established with application of sufficient electric field, however relaxation back into the disordered phase occurs on removal of the field as indicated by the loss of remenant polarization. The field against which “backswitching” (depolarization) occurs increases with temperature indicating increasing stability of the disordered regime. The disordered phase can be de-stabilized by substituting Nd for La at the A1-site and which reintroduces “normal” ferroelectric behavior.PostprintPeer reviewe

Sharp kinetic acceleration potentials during mediated redox catalysis of insulators

Redox mediators could catalyse otherwise slow and energy-inefficient cycling of Li-S and Li-O 2 batteries by shuttling electrons/holes between the electrode and the solid insulating storage materials. For mediators to work efficiently they need to oxidize the solid with fast kinetics yet the lowest possible overpotential. Here, we found that when the redox potentials of mediators are tuned via, e.g., Li + concentration in the electrolyte, they exhibit distinct threshold potentials, where the kinetics accelerate several-fold within a range as small as 10 mV. This phenomenon is independent of types of mediators and electrolyte. The acceleration originates from the overpotentials required to activate fast Li + /e – extraction and the following chemical step at specific abundant surface facets. Efficient redox catalysis at insulating solids requires therefore carefully considering the surface conditions of the storage materials and electrolyte-dependent redox potentials, which may be tuned by salt concentrations or solvents

Enhanced Photoluminescence Emission and Thermal Stability from Introduced Cation Disorder in Phosphors

Optimizing properties of phosphors for use in white-light-emitting diodes (WLEDs) is an important materials challenge. Most phosphors have a low level of lattice disorder due to mismatch between the host and activator cations. Here we show that deliberate introduction of high levels of cation disorder leads to significant improvements in quantum efficiency, stability to thermal quenching, and emission lifetime in Sr_{1.98–<i>x</i>}(Ca_0.55Ba_0.45)_<i>x</i>Si₅N₈:Eu_0.02 (<i>x</i> = 0–1.5) phosphors. Replacing Sr by a (Ca_0.55Ba_0.45) mixture with the same average radius increases cation size variance, resulting in photoluminescence emission increases of 20–26% for the <i>x</i> = 1.5 sample relative to the <i>x</i> = 0 parent across the 25–200 °C range that spans WLED working temperatures. Cation disorder suppresses nonradiative processes through disruption of lattice vibrations and creates deep traps that release electrons to compensate for thermal quenching. Introduction of high levels of cation disorder may thus be a very useful general approach for improving the efficiency of luminescent materials

The discrepancy distribution of macrophage subsets in preeclampsia placenta with or without fetal growth restriction from a small cohort

Objectives: To identify the effect of distribution characteristic of macrophages on placental function and angiogenesis in pregnancies with preeclampsia (PE) in presence of fetal growth restriction (FGR) or preeclampsia without FGR. Material and methods: The study tested the hypothesis that there was association between distribution characteristic of macrophage subsets (marked by CD68, CD163, respectively) and placental capillary development, leading to placental dysfunction in PE pregnancies with FGR (n = 36). Changes in placental parameters related with efficiency and angiogenesis and macrophage phenotypes (CD68 and CD163) were evaluated by immunohistochemistry. Pearson correlation analysis was performed to analysis the association between macrophage phenotype and placental function as well the CD34 staining, respectively. Additionally, the localization of CD68 and CD163 was assessed by using immunoflurorescence staining. Results: Pearson correlation analysis had shown the positive association between CD68 expression and microvessel formation and the reverse linear relationship between CD163 staining and placental sufficiency in PE + FGR placenta. The co-localization of CD163 and CD34 may pointed to the compensatory role of CD163 distribution involved in prompting neovascularization. Conclusions: The association between disturbed distribution of macrophages and placental efficiency and angiogenesis were only found in PE with FGR not in PE pregnancies without FGR, underlying the discrepancy role of macrophage subsets depending on the clinical phenotype of PE pregnancies

Petroleum Hydrocarbon-Degrading Bacteria for the Remediation of Oil Pollution Under Aerobic Conditions: A Perspective Analysis

With the sharp increase in population and modernization of society, environmental pollution resulting from petroleum hydrocarbons has increased, resulting in an urgent need for remediation. Petroleum hydrocarbon-degrading bacteria are ubiquitous in nature and can utilize these compounds as sources of carbon and energy. Bacteria displaying such capabilities are often exploited for the bioremediation of petroleum oil-contaminated environments. Recently, microbial remediation technology has developed rapidly and achieved major gains. However, this technology is not omnipotent. It is affected by many environmental factors that hinder its practical application, limiting the large-scale application of the technology. This paper provides an overview of the recent literature referring to the usage of bacteria as biodegraders, discusses barriers regarding the implementation of this microbial technology, and provides suggestions for further developments

The genome of hibiscus hamabo reveals its adaptation to saline and waterlogged habitat

Hibiscus hamabo is a semi-mangrove species with strong tolerance to salt and waterlogging stress. However, the molecular basis and mechanisms that underlie this strong adaptability to harsh environments remain poorly understood. Here, we assembled a high-quality, chromosome-level genome of this semi-mangrove plant and analyzed its transcriptome under different stress treatments to reveal regulatory responses and mechanisms. Our analyses suggested that H. hamabo has undergone two recent successive polyploidy events, a whole-genome duplication followed by a whole-genome triplication, resulting in an unusually large gene number (107 309 genes). Comparison of the H. hamabo genome with that of its close relative Hibiscus cannabinus, which has not experienced a recent WGT, indicated that genes associated with high stress resistance have been preferentially preserved in the H. hamabo genome, suggesting an underlying association between polyploidy and stronger stress resistance. Transcriptomic data indicated that genes in the roots and leaves responded differently to stress. In roots, genes that regulate ion channels involved in biosynthetic and metabolic processes responded quickly to adjust the ion concentration and provide metabolic products to protect root cells, whereas no such rapid response was observed from genes in leaves. Using co-expression networks, potential stress resistance genes were identified for use in future functional investigations. The genome sequence, along with several transcriptome datasets, provide insights into genome evolution and the mechanism of salt and waterlogging tolerance in H. hamabo, suggesting the importance of polyploidization for environmental adaptation.DATA AVAILABILITY: The data supporting the findings of this work are available within the paper and its Supporting Information files. The data sets generated and analyzed during this study are available from the corresponding author upon request. All the whole-genome raw data generated during this study have been deposited in the SRA database under BioProject number PRJNA759075. Transcriptome clean data have been deposited in the SRA database under BioProject number PRJNA759717. The final chromosome-scale genome assembly and annotation data have been deposited in the Figshare database (https://doi.org/10.6084/m9.figshare.19142558.v1).Six Talent Peaks Project of Jiangsu Province (NY-042); Open Fund of the Jiangsu Key Laboratory for the Research and Utilization of Plant Resources (JSPKLB201928); Talent Training Funds of the Institute of Botany, Jiangsu Province and Chinese Academy of Sciences.https://academic.oup.com/hrBiochemistryGeneticsMicrobiology and Plant Patholog

Ultra-small photoluminescent silicon-carbide nanocrystals by atmospheric-pressure plasmas

Highly size-controllable synthesis of free-standing perfectly crystalline silicon carbide nanocrystals has been achieved for the first time through a plasma-based bottom-up process. This low-cost, scalable, ligand-free atmospheric pressure technique allows fabrication of ultra-small (down to 1.5 nm) nanocrystals with very low level of surface contamination, leading to fundamental insights into optical properties of the nanocrystals. This is also confirmed by their exceptional photoluminescence emission yield enhanced by more than 5 times by reducing the nanocrystals sizes in the range of 1-5 nm, which is attributed to quantum confinement in ultra-small nanocrystals. This method is potentially scalable and readily extendable to a wide range of other classes of materials. Moreover, this ligand-free process can produce colloidal nanocrystals by direct deposition into liquid, onto biological materials or onto the substrate of choice to form nanocrystal films. Our simple but efficient approach based on non-equilibrium plasma environment is a response to the need of most efficient bottom-up processes in nanosynthesis and nanotechnology.Funding Agencies|Royal Society International Exchange Scheme [IE120884]; Leverhulme International Network [IN-2012-136]; EPSRC [EP/K022237/1, EP/M024938/1]; EU-FP7 [606889]; University of Ulster Vice-Chancellor Studentship; EU [606889]; CSIRO; Australian Research Council; School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology</p