Generation of Suprathermal Electrons by Collective Processes in Collisional Plasma

The ubiquity of high-energy tails in the charged particle velocity distribution functions observed in space plasmas suggests the existence of an underlying process responsible for taking a fraction of the charged particle population out of thermal equilibrium and redistributing it to suprathermal velocity and energy ranges. The present Letter focuses on a new and fundamental physical explanation for the origin of suprathermal electron distribution function in a highly collisional plasma. This process involves a newly discovered electrostatic bremsstrahlung emission that is effective in a plasma in which binary collisions are present. The steady-state electron velocity distribution function dictated by such a process corresponds to a Maxwellian core plus a quasi-inverse power-law tail, which is a feature commonly observed in many space plasma environment. In order to demonstrate this, the system of self-consistent particle- and wave- kinetic equations are numerically solved with an initially Maxwellian electron velocity distribution and Langmuir wave spectral intensity, which is a state that does not reflect the presence of electrostatic bremsstrahlung process, and hence not in force balance. The electrostatic bremsstrahlung term subsequently drives the system to a new force-balanced steady state. After a long integration period it is demonstrated the initial Langmuir fluctuation spectrum is modified, which in turn distorts the initial Maxwellian electron distribution into a velocity distribution that resembles the said core-suprathermal velocity distribution. Such a mechanism may thus be operative at the coronal source region, which is characterized by high collisionality.Comment: 7 pages, 2 figures. Published at: The Astrophysical Journal Letters, Volume 849, Number 2, L30. url: https://doi.org/10.3847/2041-8213/aa956

On the Distribution of Exchange Rate Regime Treatment Effects on International Trade

This paper provides evidence of heterogeneous treatment effects on trade from switching among three types of de-facto exchange rate regimes: freely floating, currency bands, and pegs or currency unions. A cottage literature at the interface of macroeconomics and international economics focuses on the consequences of exchange rate regimes for economic outcome such as trade. The majority of contributions points to trade-stimulating average effects of tighter exchange rate tying in general and of currency unions in specific. While there is great variability of the estimated quantitative effects across studies, all of the associated work adopted at least two and most of it all of the following three assumptions: assignment of countries to exchange rate regimes is random, the treatment effect of adopting a currency union is independent of the underlying regime transition, and it is homogeneous and hence fully captured by the average. This paper allows for self-selection into exchange rate regimes conditional on observable characteristics and a given regime state prior to a transition and provides evidence of strong impact heterogeneity on bilateral trade among otherwise observationally equivalent country-pairs

Quantifying non-Markovianity of continuous-variable Gaussian dynamical maps

We introduce a non-Markovianity measure for continuous-variable open quantum systems based on the idea put forward in H.-P. Breuer, that is, by quantifying the flow of information from the environment back to the open system. Instead of the trace distance we use here the fidelity to assess distinguishability of quantum states. We employ our measure to evaluate non-Markovianity of two paradigmatic Gaussian channels: the purely damping channel and the quantum Brownian motion channel with Ohmic environment. We consider different classes of Gaussian states and look for pairs of states maximizing the backflow of information. For coherent states we find simple analytical solutions, whereas for squeezed states we provide both exact numerical and approximate analytical solutions in the weak coupling limit

Experimental investigations on rising bubbles in vertical capillaries

We investigate how the walls of cylindrical capillaries affect the velocity of rising gas bubbles of various diameters. Of course, as the capillary diameter increases, the velocity of the rising bubble will approach the case of free rising. Such systematic experiments on bubble rise in capillaries, in which the ratio of bubble diameter and capillary diameter is varied from one towards smaller values, can hardly be found in literature. First orienting experiments within the system water/air have been conducted and will be discussed in this paper

The impact of packaging design on health product perceptions

Packaging design has been studied in a variety of contexts but findings remain inconsistent, particularly on the impact of individual elements (e.g. Mitchell & Papvassiliou, 1999; Becker, Rompay, Schifferstein and Galetzka, 2011; Siloyoi & Speece, 2007). Although several studies have found visual cues (picture, typography, colour) to be the most impactful on consumer attention and attitude (e.g. Folkes & Matta, 2004; Silayoi & Speece, 2004), most studies have focused on other elements such as size and shape, (e.g. Ares & Deliza, 2010) and verbal cues (e.g. Klimchuk & Krasovec, 2013). Responding to recent calls for more research (Orth, Campana & Malkewitz 2010), this study investigates the impact of both visual elements and verbal elements on consumer perceptions, specifically looking at product ‘healthiness’. To date, there is relatively little research looking at health product perceptions in the marketing literature, despite recognition that health is ‘the most significant trend and innovation driver in the global and foods drink market’ (Meziane, 2007). This paper applies conjoint analysis to examine the relative importance of four product attributes representing visual and verbal cues: level of information provided on the label (low vs high); presence of an organic ‘kite’ mark (yes/no); colour (green/orange) and the product image on the label (transparent window vs product photo). It is worth noting that despite being widely found on health food packaging, transparent windows have been considered in only one paper to date (Sioutis, 2011). Three product categories were tested (baby food, soup and coffee) across 288 UK participants. The results find verbal cues to be most important, with the amount of information provided being the key driver