COLONIZATION OF NORTHERN LOUISIANA BY THE MEDITERRANEAN GECKO, HEMIDACTYLUS TURCICUS

The Mediterranean Gecko, Hemidactylus turcicus, is known to have colonized nearly every state in the southern United States. In Louisiana, the Mediterranean Gecko has been documented in many of the southern parishes, but records for the northern portion of the state are limited. We sampled northern Louisiana parishes to document the presence of the Mediterranean Gecko. We sampled a total of 21 parishes in northern Louisiana and found geckos in 17 of those parishes, 16 of which represent new distribution records for the species. This indicates a significant range expansion of this introduced species throughout northern Louisiana. Geckos were found across a temperature range of 14.0–28.0°C and had a strong association with buildings. The species’ affinity for anthropogenic association and the continual nature of anthropogenic expansion facilitate the high vagility of this species. The result is a successful colonization throughout much of Louisiana and likely continued range expansion throughout the southern United States

B2 and G2 Toda systems on compact surfaces: a variational approach

We consider the B2 and G2 Toda systems on compact surfaces. We attack the problem using variational techniques. We get existence and multiplicity of solutions under a topological assumption on the surface and some generic conditions on the parameters. We also extend some of the results to the case of general systems.Comment: 28 pages, accepted on Journal of Mathematical Physic

Implementation of polarization diversity pulse-pair technique using airborne W-band radar

This work describes the implementation of polarization diversity on the National Research Council Canada W-band Doppler radar and presents the first-ever airborne Doppler measurements derived via polarization diversity pulse-pair processing. The polarization diversity pulse-pair measurements are interleaved with standard pulse-pair measurements with staggered pulse repetition frequency, this allows a better understanding of the strengths and drawbacks of polarization diversity, a methodology that has been recently proposed for wind-focused Doppler radar space missions. Polarization diversity has the clear advantage of making possible Doppler observations of very fast decorrelating media (as expected when deploying Doppler radars on fast-moving satellites) and of widening the Nyquist interval, thus enabling the observation of very high Doppler velocities (up to more than 100 m s−1 in the present work). Crosstalk between the two polarizations, mainly caused by depolarization at backscattering, deteriorated the quality of the observations by introducing ghost echoes in the power signals and by increasing the noise level in the Doppler measurements. In the different cases analyzed during the field campaigns, the regions affected by crosstalk were generally associated with highly depolarized surface returns and depolarization of backscatter from hydrometeors located at short ranges from the aircraft. The variance of the Doppler velocity estimates can be well predicted from theory and were also estimated directly from the observed correlation between the H-polarized and V-polarized successive pulses. The study represents a key milestone towards the implementation of polarization diversity in Doppler space-borne radars

Numerical simulations of chromospheric hard X-ray source sizes in solar flares

X-ray observations are a powerful diagnostic tool for transport, acceleration, and heating of electrons in solar flares. Height and size measurements of X-ray footpoints sources can be used to determine the chromospheric density and constrain the parameters of magnetic field convergence and electron pitch-angle evolution. We investigate the influence of the chromospheric density, magnetic mirroring and collisional pitch-angle scattering on the size of X-ray sources. The time-independent Fokker-Planck equation for electron transport is solved numerically and analytically to find the electron distribution as a function of height above the photosphere. From this distribution, the expected X-ray flux as a function of height, its peak height and full width at half maximum are calculated and compared with RHESSI observations. A purely instrumental explanation for the observed source size was ruled out by using simulated RHESSI images. We find that magnetic mirroring and collisional pitch-angle scattering tend to change the electron flux such that electrons are stopped higher in the atmosphere compared with the simple case with collisional energy loss only. However, the resulting X-ray flux is dominated by the density structure in the chromosphere and only marginal increases in source width are found. Very high loop densities (>10^{11} cm^{-3}) could explain the observed sizes at higher energies, but are unrealistic and would result in no footpoint emission below about 40 keV, contrary to observations. We conclude that within a monolithic density model the vertical sizes are given mostly by the density scale-height and are predicted smaller than the RHESSI results show.Comment: 19 pages, 9 figures, accepted for publication in Ap

Exciting dark matter in the galactic center

We reconsider the proposal of excited dark matter (DM) as an explanation for excess 511 keV gamma rays from positrons in the galactic center. We quantitatively compute the cross section for DM annihilation to nearby excited states, mediated by exchange of a new light gauge boson with off-diagonal couplings to the DM states. In models where both excited states must be heavy enough to decay into e^+ e^- and the ground state, the predicted rate of positron production is never large enough to agree with observations, unless one makes extreme assumptions about the local circular velocity in the Milky Way, or alternatively if there exists a metastable population of DM states which can be excited through a mass gap of less than 650 keV, before decaying into electrons and positrons.Comment: Dedicated to the memory of Lev Kofman; 16 pages, 9 figures; v3 added refs, minor changes, accepted to PR

Country-of-origin effect and firm reputation influence in business-to-business markets with high cultural distance

Italy is renowned around the world for its design, fashion, Mediterranean cuisine and other \u201cMade in Italy\u201d-styled products. These products are often associated with known and famous brands especially in the luxury sector, but many less well-known Italian firms operating in more technical industries, such as in the mechanical or electronic sectors, have a major presence in international markets (Bertoli & Resciniti, 2012; Fortis, 2005). Country-of-Origin (COO) literature is mainly focused on consumer sectors. The amount of literature on the subject in the industrial sector is lower and among theorists, two main research streams can be identified. Some believe that COO has the same importance as the consumer market, while others assert that industrial customers, operating in a more informed way, are less likely to be influenced by it. This present contribution falls within the realm of this debate. While focusing on the importance of COOfor companies operating in BTB sectors, itwas considered appropriate to contextualize this strategic element within marketing and internationalization strategies developed by companies operating in geographically and culturally distant markets. For this reason, we chose a group of Italian companies operating in the Chinese market for the empirical study. In the discussion of findings, particular emphasis will be given to typical elements of marketing mix in BTB, such as the relational aspect and trust. The paper covers the following steps: first, a brief analysis of the literature on COO is provided, with a focus on BTB; then the research methodology is described; after this, findings concerning the marketing and internationalization strategies adopted by firms operating in markets with high geographical and cultural distance are set out and there is discussion of the importance of COO, firm reputation and brand image in the internationalization process; and finally we offer managerial implications, limitations and suggestions for future research

Italian country image: the impact on business models and relations in Chinese business-to-business markets

Italy is renowned around the world for its design, fashion, Mediterranean cuisine and other Made in Italy products. These products are often associated with known and famous brands, especially in the luxury sector, but many less well-known Italian firms operating in more technical industries, such as in the mechanical or electronic sectors, have a major presence in international markets. These traditional Made in Italy sectors as well as the specialized product sectors create the so-called \u20184Fs\u2019 of Italian excellence. The first group together traditional consumer goods linked to the person and the home. Specialized product sectors include the automation-\u2013mechanical-\u2013rubber-\u2013plastics sector. Despite offering excellent quality products in these sectors, Italy has a lower perceived image than other countries such as Germany. Country of oOrigin (COO) literature is mainly focused on consumer sectors. The abundance of literature on the subject in the industrial sector is lower, and among theorists, two main research streams can be identified. Some believe that COO has the same importance in the consumer market, while others assert that industrial customers operating in a more informed way are less likely to be influenced by it. This present contributionchapter falls within this debate, with the aim of verifying if the COO effect really matters in business-to-business (BTB) relations, particularly in business relations between firms that belong to markets with high cultural distance. We selected China with reference to this investigation. A second objective is to identify the elements that come into play in the evaluation of Italian offers and whether there are differences of perception according to the business sector considered. The methodology used foresees a study developed over three stages (the first stage is quantitative, the second and third stages are qualitative) on a sample of 338 firms in the first quantitative phase and 14 in the subsequent qualitative phases

OUTLIER DETECTION AND ESTIMATION IN NON LINEAR TIME SERIES

The problem of identifying the time location and estimating the amplitude of outliers in non-linear time series is addressed. A model-based method is proposed for detecting the presence of additive or innovational outliers when the series is generated by a general non-linear model. We use this method for identifying and estimating outliers in bilinear, self-exciting threshold autoregressive and exponential autoregressive models. A simulation study is performed to test the proposed procedures and comparing them to the methods based on linear models and linear interpolators. Finally, our results are applied for detecting outliers in the Canadian lynx trappings and in the sunspot numbers data