Estimation of the mean of a discrete parameter, covariance stationary, stochastic process in rotation sampling

Constrained optimization procedure for deriving linear estimator of population mean in rotation samplin

X-ray Dust Scattering at Small Angles: The Complete Halo around GX13+1

The exquisite angular resolution available with Chandra should allow precision measurements of faint diffuse emission surrounding bright sources, such as the X-ray scattering halos created by interstellar dust. However, the ACIS CCDs suffer from pileup when observing bright sources, and this creates difficulties when trying to extract the scattered halo near the source. The initial study of the X-ray halo around GX13+1 using only the ACIS-I detector done by Smith, Edgar & Shafer (2002) suffered from a lack of sensitivity within 50'' of the source, limiting what conclusions could be drawn. To address this problem, observations of GX13+1 were obtained with the Chandra HRC-I and simultaneously with the RXTE PCA. Combined with the existing ACIS-I data, this allowed measurements of the X-ray halo between 2-1000''. After considering a range of dust models, each assumed to be smoothly distributed with or without a dense cloud along the line of sight, the results show that there is no evidence in this data for a dense cloud near the source, as suggested by Xiang et al. (2005). Finally, although no model leads to formally acceptable results, the Weingartner & Draine (2001) and nearly all of the composite grain models from Zubko, Dwek & Arendt (2004) give poor fits.Comment: 8 pages, 6 figures, accepted for publication in Ap

Combining Thesaurus Knowledge and Probabilistic Topic Models

In this paper we present the approach of introducing thesaurus knowledge into probabilistic topic models. The main idea of the approach is based on the assumption that the frequencies of semantically related words and phrases, which are met in the same texts, should be enhanced: this action leads to their larger contribution into topics found in these texts. We have conducted experiments with several thesauri and found that for improving topic models, it is useful to utilize domain-specific knowledge. If a general thesaurus, such as WordNet, is used, the thesaurus-based improvement of topic models can be achieved with excluding hyponymy relations in combined topic models.Comment: Accepted to AIST-2017 conference (http://aistconf.ru/). The final publication will be available at link.springer.co

Dynamics of tilt-based browsing on mobile devices

A tilt-controlled photo browsing method for small mobile devices is presented. The implementation uses continuous inputs from an accelerometer, and a multimodal (visual, audio and vibrotactile) display coupled with the states of this model. The model is based on a simple physical model, with its characteristics shaped to enhance usability. We show how the dynamics of the physical model can be shaped to make the handling qualities of the mobile device fit the browsing task. We implemented the proposed algorithm on Samsung MITs PDA with tri-axis accelerometer and a vibrotactile motor. The experiment used seven novice users browsing from 100 photos. We compare a tilt-based interaction method with a button-based browser and an iPod wheel. We discuss the usability performance and contrast this with subjective experience from the users. The iPod wheel has significantly poorer performance than button pushing or tilt interaction, despite its commercial popularity

First Results from Dark Matter Search Experiment in the Nokogiriyama Underground Cell

An experiment to search for hypothetical particle dark matter using cryogenic thermal detector, or bolometer is ongoing. The bolometer consists of eight pieces of 21 g LiF absorbers and sensitive NTD germanium thermistors attached to them and is installed in the Nokogiriyama underground cell which is a shallow depth site ($\sim 15$ m w.e.). We report on the results from the first running for about ten days using this arrayed bolometer system together with appropriate shieldings and muon veto counters. From the obtained energy spectra the exclusion limits for the cross section of the elastic neutralino-proton scattering are derived under commonly accepted astrophysical assumptions. The sensitivity for the light neutralino with a mass below 5 GeV is improved by this work.Comment: 8 pages, Revtex, 4 figure

Large-Scale Modelling of the Environmentally-Driven Population Dynamics of Temperate Aedes albopictus (Skuse)

The Asian tiger mosquito, Aedes albopictus, is a highly invasive vector species. It is a proven vector of dengue and chikungunya viruses, with the potential to host a further 24 arboviruses. It has recently expanded its geographical range, threatening many countries in the Middle East, Mediterranean, Europe and North America. Here, we investigate the theoretical limitations of its range expansion by developing an environmentally-driven mathematical model of its population dynamics. We focus on the temperate strain of Ae. albopictus and compile a comprehensive literature-based database of physiological parameters. As a novel approach, we link its population dynamics to globally-available environmental datasets by performing inference on all parameters. We adopt a Bayesian approach using experimental data as prior knowledge and the surveillance dataset of Emilia-Romagna, Italy, as evidence. The model accounts for temperature, precipitation, human population density and photoperiod as the main environmental drivers, and, in addition, incorporates the mechanism of diapause and a simple breeding site model. The model demonstrates high predictive skill over the reference region and beyond, confirming most of the current reports of vector presence in Europe. One of the main hypotheses derived from the model is the survival of Ae. albopictus populations through harsh winter conditions. The model, constrained by the environmental datasets, requires that either diapausing eggs or adult vectors have increased cold resistance. The model also suggests that temperature and photoperiod control diapause initiation and termination differentially. We demonstrate that it is possible to account for unobserved properties and constraints, such as differences between laboratory and field conditions, to derive reliable inferences on the environmental dependence of Ae. albopictus populations

Calculation of composition distribution of ultrafine ion-H2O-H2SO4 clusters using a modified binary ion nucleation theory

Thomson's ion nucleation theory was modified to include the effects of curvature dependence of the microscopic surface tension of field dependent, nonlinear, dielectric properties of the liquid; and of sulfuric acid hydrate formation in binary mixtures of water and sulfuric acid vapors. The modified theory leads to a broadening of the ion cluster spectrum, and shifts it towards larger numbers of H2O and H2SO4 molecules. Whether there is more shifting towards larger numbers of H2O or H2SO4 molecules depends on the relative humidity and relative acidity of the mixture. Usually, a broadening of the spectrum is accompanied by a lowering of the mean cluster intensity. For fixed values of relative humidity and relative acidity, a similar broadening pattern is observed when the temperature is lowered. These features of the modified theory illustrate that a trace of sulfuric acid can facilitate the formation of ultrafine, stable, prenucleation ion clusters as well as the growth of the prenucleation ion clusters towards the critical saddle point conditions, even with low values of relative humidity and relative acidity

Termination of Electron Acceleration in Thundercloud by Intra/Inter-cloud Discharge

An on-ground observation program for high energy atmospheric phenomena in winter thunderstorms along Japan Sea has been performed via measurements of gamma-ray radiation, atmospheric electric field and low-frequency radio band. On February 11, 2017, the radiation detectors recorded gamma-ray emission lasting for 75 sec. The gamma-ray spectrum extended up to 20 MeV and was reproduced by a cutoff power-law model with a photon index of $1.36^{+0.03}_{-0.04}$, being consistent with a Bremsstrahlung radiation from a thundercloud (as known as a gamma-ray glow and a thunderstorm ground enhancement). Then the gamma-ray glow was abruptly terminated with a nearby lightning discharge. The low-frequency radio monitors, installed $\sim$50 km away from the gamma-ray observation site recorded leader development of an intra/inter-cloud discharge spreading over $\sim$60 km area with a $\sim$300 ms duration. The timing of the gamma-ray termination coincided with the moment when the leader development of the intra/inter-cloud discharge passed 0.7 km horizontally away from the radiation monitors. The intra/inter-cloud discharge started $\sim$15 km away from the gamma-ray observation site. Therefore, the glow was terminated by the leader development, while it did not trigger the lightning discharge in the present case.Comment: 12 pages, 4 figures, accepted for publication in Geophysical Research Letter