Edge-enhanced disruptive camouflage impairs shape discrimination

Disruptive colouration (DC) is a form of camouflage comprised of areas of pigmentation across a target’s surface that form false edges, which are said to impede detection by disguising the outline of the target. In nature, many species with DC also exhibit edge enhancement (EE); light areas have lighter edges and dark areas have darker edges. EE DC has been shown to undermine not only localisation but also identification of targets, even when they are not hidden (Sharman, Moncrieff, & Lovell, 2018). We use a novel task, where participants judge which “snake” is more “wiggly,” to measure shape discrimination performance for three colourations (uniform, DC, and EE DC) and two backgrounds (leafy and uniform). We show that EE DC impairs shape discrimination even when targets are not hidden in a textured background. We suggest that this mechanism may contribute to misidentification of EE DC targets

Behind the price: on the role of agent's reflexivity in financial market microstructure

In this chapter we review some recent results on the dynamics of price formation in financial markets and its relations with the efficient market hypothesis. Specifically, we present the limit order book mechanism for markets and we introduce the concepts of market impact and order flow, presenting their recently discovered empirical properties and discussing some possible interpretation in terms of agent's strategies. Our analysis confirms that quantitative analysis of data is crucial to validate qualitative hypothesis on investors' behavior in the regulated environment of order placement and to connect these micro-structural behaviors to the properties of the collective dynamics of the system as a whole, such for instance market efficiency. Finally we discuss the relation between some of the described properties and the theory of reflexivity proposing that in the process of price formation positive and negative feedback loops between the cognitive and manipulative function of agents are present.Comment: 12 pages, 1 figur

Dissociating the effect of disruptive colouration on localisation and identification of camouflaged targets

Disruptive camouflage features contrasting areas of pigmentation across the animals’ surface that form false edges which disguise the shape of the body and impede detection. In many taxa these false edges feature local contrast enhancement or edge enhancement, light areas have lighter edges and dark areas have darker edges. This additional quality is often overlooked in existing research. Here we ask whether disruptive camouflage can have benefits above and beyond concealing location. Using a novel paradigm, we dissociate the time courses of localisation and identification of a target in a single experiment. We measured the display times required for a stimulus to be located or identified (the critical duration). Targets featured either uniform, disruptive or edge enhanced disruptive colouration. Critical durations were longer for identifying targets with edge enhanced disruptive colouration camouflage even when presented against a contrasting background, such that all target types were located equally quickly. For the first time, we establish empirically that disruptive camouflage not only conceals location, but also disguises identity. This shows that this form of camouflage can be useful even when animals are not hidden. Our findings offer insights into how edge enhanced disruptive colouration undermines visual perception by disrupting object recognition

Two-probe theory of scanning tunneling microscopy of single molecules: Zn(II)-etioporphyrin on alumina

We explore theoretically the scanning tunneling microscopy of single molecules on substrates using a framework of two local probes. This framework is appropriate for studying electron flow in tip/molecule/substrate systems where a thin insulating layer between the molecule and a conducting substrate transmits electrons non-uniformly and thus confines electron transmission between the molecule and substrate laterally to a nanoscale region significantly smaller in size than the molecule. The tip-molecule coupling and molecule-substrate coupling are treated on the same footing, as local probes to the molecule, with electron flow modelled using the Lippmann-Schwinger Green function scattering technique. STM images are simulated for various positions of the stationary (substrate) probe below a Zn(II)-etioporphyrin I molecule. We find that these images have a strong dependence on the substrate probe position, indicating that electron flow can depend strongly on both tip position and the location of the dominant molecule-substrate coupling. Differences in the STM images are explained in terms of the molecular orbitals that mediate electron flow in each case. Recent experimental results, showing STM topographs of Zn(II)-etioporphyrin I on alumina/NiAl(110) to be strongly dependent on which individual molecule on the substrate is being probed, are explained using this model. A further experimental test of the model is also proposed.Comment: Physical Review B, in pres

Middle-Age Job Mobility: Its Determinants and Consequences

Our paper uses the wealth of information available in the NLS to expand on previous work in several ways. First, we investigate whether there is a meaningful distinction among types of job separations. Traditional analysis has categorized job separations as either employee-initiated (quits) or employer-initiated (layoffs). We question whether this dichotomy is correct. The National Longitudinal Survey data is especially useful for studying the relationship between wages and the probability of quitting. Most theoretical work on the determinants of job separation concludes that the probability of changing jobs is related to a reservation wage. The NLS data set allows us to test this relationship since it includes information on the individual's "hypothetical wage"-- that is, the wage required to induce the individual to accept another job. Given this information, we are able to compare the effects of different measures of the individual's price of time (e.g. the current wage and the reservation wage) on the probability of quitting. In addition, we analyze the role of human capital variables, job related characteristics and family background in the determination of job mobility. The analysis of the determinants of job separations in the cross-section naturally leads to an investigation of the relationship between previous separations and future separations. In particular, we consider whether such a relationship exists, and whether the nature of previous separations is a good predictor of the nature of future separations. Finally, we analyze the effects of job mobility on earnings and on job satisfaction. We distinguish between the immediate gains to mobility and the future gains to mobility, and also consider whether the nature of the separation is an important determinant of the consequences of job mobility.

Wage Growth and Job Turnover: An Empirical Analysis

This paper demonstrates that labor turnover is a significant factor in understanding wage growth since it affects both wage growth across jobs and wage growth within the job. Our analysis shows that young men who quit experience significant wage gains compared to stayers and compared to their own wage growth prior to the job change. Among older men, a quit increases wage growth only if the individual said he changed jobs because he found a better job. Yet in both age groups, individuals who expect to remain on the current job experience steeper wage growth per time period on that job. Thus labor turnover has offsetting effects on wage growth, leading to wage gains across jobs but flatter growth in shorter jobs. Our empirical analysis shows however that total life-cycle wage growth is positively related to current tenure. While early mobility may pay, individuals who are still changing jobs later in life experience lower overall wage growth.

Non-Zhang-Rice singlet character of the first ionization state of T-CuO

We argue that tetragonal CuO (T-CuO) has the potential to finally settle long-standing modelling issues for cuprate physics. We compare the one-hole quasiparticle (qp) dispersion of T-CuO to that of cuprates, in the framework of the strongly-correlated ($U_{dd}\rightarrow \infty$) limit of the three-band Emery model. Unlike in CuO$_2$, magnetic frustration in T-CuO breaks the $C_4$ rotational symmetry and leads to strong deviations from the Zhang-Rice singlet picture in parts of the reciprocal space. Our results are consistent with angle-resolved photoemission spectroscopy data but in sharp contradiction to those of a one-band model previously suggested for them. These differences identify T-CuO as an ideal material to test a variety of scenarios proposed for explaining cuprate phenomenology.Comment: 4 pages, 2 figure

Gravity on a Little Warped Space

We investigate the consistent inclusion of 4D Einstein gravity on a truncated slice of AdS_5 whose bulk-gravity and UV scales are much less than the 4D Planck scale, M_* << M_{Pl}. Such "Little Warped Spaces" have found phenomenological utility and can be motivated by string realizations of the Randall-Sundrum framework. Using the interval approach to brane-world gravity, we show that the inclusion of a large UV-localized Einstein-Hilbert term allows one to consistently incorporate 4D Einstein gravity into the low-energy theory. We detail the spectrum of Kaluza-Klein metric fluctuations and, in particular, examine the coupling of the little radion to matter. Furthermore, we show that Goldberger-Wise stabilization can be successfully implemented on such spaces. Our results demonstrate that realistic low-energy effective theories can be constructed on these spaces, and have relevance for existing models in the literature.Comment: 1+24 page

On the location of a possible spawning area for the penaeid prawn, Metapenaeus monoceros Fabricius, off Cochin

We have very little information on the exact areas where many of the penreid prawns of our coast mature and breed except for the smaller species, Metapenceus dobsoni and Pampeneopsis stylifera (Menon, 1951 and 1953