Are Coronae of Magnetically Active Stars Heated by Flares? III. Analytical Distribution of Superimposed Flares

(abridged) We study the hypothesis that observed X-ray/extreme ultraviolet emission from coronae of magnetically active stars is entirely (or to a large part) due to the superposition of flares, using an analytic approach to determine the amplitude distribution of flares in light curves. The flare-heating hypothesis is motivated by time series that show continuous variability suggesting the presence of a large number of superimposed flares with similar rise and decay time scales. We rigorously relate the amplitude distribution of stellar flares to the observed histograms of binned counts and photon waiting times, under the assumption that the flares occur at random and have similar shapes. Applying these results to EUVE/DS observations of the flaring star AD Leo, we find that the flare amplitude distribution can be represented by a truncated power law with a power law index of 2.3 +/- 0.1. Our analytical results agree with existing Monte Carlo results of Kashyap et al. (2002) and Guedel et al. (2003). The method is applicable to a wide range of further stochastically bursting astrophysical sources such as cataclysmic variables, Gamma Ray Burst substructures, X-ray binaries, and spatially resolved observations of solar flares.Comment: accepted for publication in Ap

Who Shapes Climate Action in India? Insights from the Wind and Solar Energy Sectors

The years since the UN Framework Convention on Climate Change (UNFCCC) was signed in 1992 have been marked by rising concern about the climate problem, given that emissions have continued to rise and atmospheric concentrations have continued to build up to a level where the likelihood of avoiding dangerous climate change – a key objective of the UNFCCC – is diminishing. In fact, atmospheric carbon dioxide levels recently crossed the 400 ppm mark for the first time in human history. At the same time, the UNEP Emissions Gap Report 2012 (UNEP 2012) has highlighted the large gap between the national mitigation pledges in the Copenhagen Accord and the level of reductions that are required for a ‘likely’ chance of staying below the 2°C target; according to other analysts, these combined mitigation pledges – ‘[are] consistent with a global temperature rise of greater than 2°C – and possibly as much as 5°C’ (Kartha and Erickson 2011). Within this paper, we specifically take an actor-centred perspective – focusing on players not just within the government but also private sector and civil society – to better understand the influence of such actors in shaping climate change action within India. Through this analysis, we aim to explore the underlying domestic political economy as well as the international linkages shaping climate action.UK Department for International Developmen

Quantum-gravity-induced matter self-interactions in the asymptotic-safety scenario

We investigate the high-energy properties of matter theories coupled to quantum gravity. Specifically, we show that quantum gravity fluctuations generically induce matter self-interactions in a scalar theory. Our calculations apply within asymptotically safe quantum gravity, where our results indicate that the UV is dominated by an interacting fixed point, with non-vanishing gravitational as well as matter couplings. In particular, momentum-dependent scalar self-interactions are non-zero and induce a non-vanishing momentum-independent scalar potential. Furthermore we point out that terms of this type can have observable consequences in the context of scalar-field driven inflation, where they can induce potentially observable non-Gaussianities in the CMB.Comment: 15 + 8 pages, 8 figures, extended truncation, version to be published in PR

One Loop Beta Functions in Topologically Massive Gravity

We calculate the running of the three coupling constants in cosmological, topologically massive 3d gravity. We find that \nu, the dimensionless coefficient of the Chern-Simons term, has vanishing beta function. The flow of the cosmological constant and Newton's constant depends on \nu, and for any positive \nu there exist both a trivial and a nontrivial fixed point.Comment: 44 pages, 16 figure

Comment on the Generation Number in Orbifold Compactifications

There has been some confusion concerning the number of $(1,1)$-forms in orbifold compactifications of the heterotic string in numerous publications. In this note we point out the relevance of the underlying torus lattice on this number. We answer the question when different lattices mimic the same physics and when this is not the case. As a byproduct we classify all symmetric $Z_N$-orbifolds with $(2,2)$ world sheet supersymmetry obtaining also some new ones.Comment: 28 pages, 9 figures not included, available in postscript at reques

Polarization and magnetization dynamics of a field-driven multiferroic structure

We consider a multiferroic chain with a linear magnetoelectric coupling induced by the electrostatic screening at the ferroelectric/ferromagnet interface. We study theoretically the dynamic ferroelectric and magnetic response to external magnetic and electric fields by utilizing an approach based on coupled Landau- Khalatnikov and finite-temperature Landau-Lifshitz-Gilbert equations. Additionally, we compare with Monte Carlo calculations. It is demonstrated that for material parameters corresponding to BaTiO3/Fe the polarization and the magnetization are controllable by external magnetic and electric fields respectively

Network-wide Configuration Synthesis

Computer networks are hard to manage. Given a set of high-level requirements (e.g., reachability, security), operators have to manually figure out the individual configuration of potentially hundreds of devices running complex distributed protocols so that they, collectively, compute a compatible forwarding state. Not surprisingly, operators often make mistakes which lead to downtimes. To address this problem, we present a novel synthesis approach that automatically computes correct network configurations that comply with the operator's requirements. We capture the behavior of existing routers along with the distributed protocols they run in stratified Datalog. Our key insight is to reduce the problem of finding correct input configurations to the task of synthesizing inputs for a stratified Datalog program. To solve this synthesis task, we introduce a new algorithm that synthesizes inputs for stratified Datalog programs. This algorithm is applicable beyond the domain of networks. We leverage our synthesis algorithm to construct the first network-wide configuration synthesis system, called SyNET, that support multiple interacting routing protocols (OSPF and BGP) and static routes. We show that our system is practical and can infer correct input configurations, in a reasonable amount time, for networks of realistic size (> 50 routers) that forward packets for multiple traffic classes.Comment: 24 Pages, short version published in CAV 201

Application of artificial neural networks in hydrological modeling: A case study of runoff simulation of a Himalayan glacier basin

The simulation of runoff from a Himalayan Glacier basin using an Artificial Neural Network (ANN) is presented. The performance of the ANN model is found to be superior to the Energy Balance Model and the Multiple Regression model. The RMS Error is used as the figure of merit for judging the performance of the three models, and the RMS Error for the ANN model is the latest of the three models. The ANN is faster in learning and exhibits excellent system generalization characteristics

Progress in Diarrheal Disease Research at Namru-2 in Collaboration with Badan Litbangkes and Rspi

Penyakit diare termasuk kolera masih merupakan masalah kesehatan yang penting untuk Indonesia. Kejadian luar biasa (KLB) "muntah-berak" masih terus dilaporkan dari berbagai daerah di Indonesia. Salah satu upaya yang dilakukan untuk mengatasi keadaan ini adalah menemukan suatu vaksin yang aman, praktis dan terjangkau harganya. CVD-103 adalah strain V. cholerae yang sebagian besar gen penyebab diare, toksin subunit A, telah dibuang. Pada penelitian dengan peserta anak-anak di Jakarta, CVD 103-HgR ternyata memberikan kenaikan antibodi dan dapat diterima baik oleh anak-anak Indonesia berusia 5-9 tahun dan 25-59 bulan. Di samping itu pemeriksaan sampel bakteriologik dari lingkungan dekat tempat kediaman peserta dengan menggunakan teknik yang peka untuk mendeteksi V. cholerae, tidak menemukan adanya strain vaksin. Suatu penelitian lapangan dengan tujuan untuk menilai kemanjuran dosis tunggal vaksin oral kolera CVD 103-HgR untuk pencegahan kolera secara klinis selama tiga tahun, telah dimulai didaerah Jakarta Utara pada tahun 1993. Selain itu penelitian ini juga bertujuan untuk menetapkan kemanjuran vaksin terhadap berbagai kelompok umur, terhadap kolera berat, serta membandingkan kemanjurannya pada peserta dengan golongan darah O. Jumlah penduduk yang ikut dalam penilaian vaksin ini adalah 67.000 peserta sukarela. Hasil penelitian ini diharapkan dapat diketahui pada akhir tahun 1996.Di samping penelitian tentang vaksin kolera, NAMRU dan Badan Litbangkes juga telah ikut serta dalam berbagai penelitian WHO, misalnya tentang larutan garam oralit (ORS) yang dilakukan di RS Karantina/RS Penyakit Infeksi Prof. Dr. Sulianti Saroso. Salah satu penelitian terakhir adalah manfaat larutan ORS dengan osmolaritas rendah pada tahun 1994. Hasil penelitian ini telah mendorong WHO untuk melaksanakan penelitian dengan larutan yang sama di berbagai pusat penelitian (multicenter) pada tahun 1995 sebelum mengusulkan suatu Perubahan formulasi larutan ORS secara global