1,170 research outputs found

    On the Weakening of Chromospheric Magnetic Field in Active Regions

    Full text link
    Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields at the photosphere and chromosphere are presented. Fe I line at λ6569\lambda6569 and HαH_{\alpha} at λ6563\lambda6563 are used respectively for deriving the physical parameters at photospheric and chromospheric heights. The LOS magnetic field obtained through the center-of-gravity method show a linear relation between photospheric and chromospheric field for field strengths less than 700 G. But in strong field regions, the LOS magnetic field values derived from HαH_{\alpha} are much weaker than what one gets from the linear relationship and also from those expected from the extrapolation of the photospheric magnetic field. We discuss in detail the properties of magnetic field observed in HαH_{\alpha} from the point of view of observed velocity gradients. The bisector analysis of HαH_{\alpha} Stokes II profiles show larger velocity gradients in those places where strong photospheric magnetic fields are observed. These observations may support the view that the stronger fields diverge faster with height compared to weaker fields.Comment: accepted for publication in Ap

    Spatial synchronization and extinction of species under external forcing

    Get PDF
    We study the interplay between synchronization and extinction of a species. Using a general model we show that under a common external forcing, the species with a quadratic saturation term in the population dynamics first undergoes spatial synchronization and then extinction, thereby avoiding the rescue effect. This is because the saturation term reduces the synchronization time scale but not the extinction time scale. The effect can be observed even when the external forcing acts only on some locations provided there is a synchronizing term in the dynamics. Absence of the quadratic saturation term can help the species to avoid extinction.Comment: 4 pages, 2 figure

    Gravitational Baryogenesis: Problems and Possible Resolution

    Full text link
    The coupling of baryonic current to the derivative of the curvature scalar, RR, inherent to gravitational baryogenesis (GBG), leads to a fourth order differential equation of motion for RR instead of the algebraic one of General Relativity (GR). The fourth-order differential equation is generically unstable. We consider a possible mechanism of stabilization of GBG by modification of gravity, introducing an R2R^2-term into the canonical action of GR. It is shown that this mechanism allows for stabilization of GBG with bosonic and fermionic baryon currents. We have established the region of the model parameters leading to stabilization of RR. Still, the standard cosmology would be noticeably modified.Comment: 11 pages, no figures, presented at 6th6^{th} International Conference on Particle Physics and Astrophysics (ICCPA-2022)}. arXiv admin note: text overlap with arXiv:1808.0857

    Improving Sanitation at Scale: Lessons From TSSM Implementation in East Java, Indonesia

    Full text link
    Low-quality or nonexistent sanitation affects health and hinders economic development, especially in the world's poorest countries. To address this issue, the Water and Sanitation Program, a partnership administered by the World Bank and funded by the Bill & Melinda Gates Foundation, launched a global initiative in 2006 at selected sites in India, Indonesia, and Tanzania. In Indonesia, the program was known as the Total Sanitation and Sanitation Marketing initiative, which moved beyond simply building sanitation "hardware" and relied, instead, on providing training and technical assistance to promote collective action to eliminate open defecation and to strengthen demand for and supply of sanitation products and services

    Generalization of Linearized Gouy-Chapman-Stern Model of Electric Double Layer for Nanostructured and Porous Electrodes: Deterministic and Stochastic Morphology

    Full text link
    We generalize linearized Gouy-Chapman-Stern theory of electric double layer for nanostructured and morphologically disordered electrodes. Equation for capacitance is obtained using linear Gouy-Chapman (GC) or Debye-u¨\rm{\ddot{u}}ckel equation for potential near complex electrode/electrolyte interface. The effect of surface morphology of an electrode on electric double layer (EDL) is obtained using "multiple scattering formalism" in surface curvature. The result for capacitance is expressed in terms of the ratio of Gouy screening length and the local principal radii of curvature of surface. We also include a contribution of compact layer, which is significant in overall prediction of capacitance. Our general results are analyzed in details for two special morphologies of electrodes, i.e. "nanoporous membrane" and "forest of nanopillars". Variations of local shapes and global size variations due to residual randomness in morphology are accounted as curvature fluctuations over a reference shape element. Particularly, the theory shows that the presence of geometrical fluctuations in porous systems causes enhanced dependence of capacitance on mean pore sizes and suppresses the magnitude of capacitance. Theory emphasizes a strong influence of overall morphology and its disorder on capacitance. Finally, our predictions are in reasonable agreement with recent experimental measurements on supercapacitive mesoporous systems

    Amplitude death in complex networks induced by environment

    Full text link
    We present a mechanism for amplitude death in coupled nonlinear dynamical systems on a complex network having interactions with a common environment-like external system. We develop a general stability analysis that is valid for any network topology and obtain the threshold values of coupling constants for the onset of amplitude death. An important outcome of our study is a universal relation between the critical coupling strength and the largest non-zero eigenvalue of the coupling matrix. Our results are fully supported by the detailed numerical analysis for different network topologies.Comment: 7 pages, 7 figure

    Making On-Demand Routing Efficient with Route-Request Aggregation

    Full text link
    In theory, on-demand routing is very attractive for mobile ad hoc networks (MANET), because it induces signaling only for those destinations for which there is data traffic. However, in practice, the signaling overhead of existing on-demand routing protocols becomes excessive as the rate of topology changes increases due to mobility or other causes. We introduce the first on-demand routing approach that eliminates the main limitation of on-demand routing by aggregating route requests (RREQ) for the same destinations. The approach can be applied to any existing on-demand routing protocol, and we introduce the Ad-hoc Demand-Aggregated Routing with Adaptation (ADARA) as an example of how RREQ aggregation can be used. ADARA is compared to AODV and OLSR using discrete-event simulations, and the results show that aggregating RREQs can make on-demand routing more efficient than existing proactive or on-demand routing protocols

    myo-Inositol Oxygenase is Required for Responses to Low Energy Conditions in Arabidopsis thaliana

    Get PDF
    myo-Inositol is a precursor for cell wall components, is used as a backbone of myo-inositol trisphosphate (Ins(1,4,5)P3) and phosphatidylinositol phosphate signaling molecules, and is debated about whether it is also a precursor in an alternate ascorbic acid synthesis pathway. Plants control inositol homeostasis by regulation of key enzymes involved in myo-inositol synthesis and catabolism. Recent transcriptional profiling data indicate up-regulation of the myo-inositol oxygenase (MIOX) genes under conditions in which energy or nutrients are limited. To test whether the MIOX genes are required for responses to low energy, we first examined MIOX2 and MIOX4 gene expression regulation by energy/nutrient conditions. We found that both MIOX2 and MIOX4 expression are suppressed by exogenous glucose addition in the shoot, but not in the root. Both genes were abundantly expressed during low energy/nutrient conditions. Loss-of-function mutants in MIOX genes contain alterations in myo-inositol levels and growth changes in the root. Miox2 mutants can be complemented with a MIOX2:green fluorescent protein fusion. Further we show here that MIOX2 is a cytoplasmic protein, while MIOX4 is present mostly in the cytoplasm, but also occasionally in the nucleus. Together, these data suggest that MIOX catabolism in the shoot may influence root growth responses during low energy/nutrient conditions

    Comment on "Mean First Passage Time for Anomalous Diffusion"

    Full text link
    We correct a previously erroneous calculation [Phys. Rev. E 62, 6065 (2000)] of the mean first passage time of a subdiffusive process to reach either end of a finite interval in one dimension. The mean first passage time is in fact infinite.Comment: To appear in Phys. Rev.
    corecore