On the decline of 1st and 2nd order sensitivity with eccentricity

We studied the relationship between the decline in sensitivity that occurs with eccentricity for stimuli of different spatial scale defined by either luminance (LM) or contrast (CM) modulation. We show that the detectability of CM stimuli declines with eccentricity in a spatial frequency-dependent manner, and that the rate of sensitivity decline for CM stimuli is roughly that expected from their 1st order carriers, except, possibly, at finer scales. Using an equivalent noise paradigm, we investigated the possible reasons for why the foveal sensitivity for detecting LM and CM stimuli differs as well as the reason why the detectability of 1st order stimuli declines with eccentricity. We show the former can be modeled by an increase in internal noise whereas the latter involves both an increase in internal noise and a loss of efficiency. To encompass both the threshold and suprathreshold transfer properties of peripheral vision, we propose a model in terms of the contrast gain of the underlying mechanisms.

Follow-ups and interpreter-mediated discourse

The edited volume documents the proceedings of the ESF workshop "Follow-ups across discourse domains: a cross-cultural exploration of their forms and functions". It examines the forms and functions of the dialogue act of a follow-up, viz. accepting or challenging a prior communicative act, in political discourse across spoken and written dialogic genres. Specifically, it considers (1) the discourse domains of political interviews, editorials, op-eds and discussion forums, (2) their sequential organization as regards the status of initial (or 1st order) follow-up, a follow-up of a prior follow-up (2nd order follow-up), or nth-order follow-up, and (3) their discursive realization as regards degrees of indirectness and responsiveness which are conceptualized as a continuum along the lines of degrees of explicitness and degrees of responsiveness. The chapters come from the fields of linguistics, discourse analysis, socio-pragmatics, communication, political science and psychology, examining the heterogeneous field of political discourse and its manifestation in diverse discourse genres with respect to evasiveness, indirectness and redundancy in mediated political discourse, professional discourse, discourse identity and doing politics, to name but the most prominent questions.

Ultrafast all-optical Nth-order differentiator based on chirped fiber Bragg gratings

In this letter we present a technique for the implementation of Nth-order ultrafast temporal differentiators. This technique is based on two oppositely chirped fiber Bragg gratings in which the grating profile maps the spectral response of the Nth-order differentiator. Examples of 1st, 2nd, and 4th order differentiators are designed and numerically simulated.