On Rational Delegations in Liquid Democracy

Liquid democracy is a proxy voting method where proxies are delegable. We propose and study a game-theoretic model of liquid democracy to address the following question: when is it rational for a voter to delegate her vote? We study the existence of pure-strategy Nash equilibria in this model, and how group accuracy is affected by them. We complement these theoretical results by means of agent-based simulations to study the effects of delegations on group's accuracy on variously structured social networks.Comment: 17 pages, 3 figures. This paper (without Appendix) appears in the proceedings of AAAI'1

Resonant nonlinear spectroscopy in strong fields

A method is presented to describe multiple resonant nonlinear spectra in the presence of strong laser fields. The Liouville equation for the d. operator of the mol. system is transformed to a time-independent linear equation system. This can be easily solved rigorously by numerical methods or, after partitioning into a strong-field part and a perturbation, the soln. can be obtained anal. by a novel perturbative approach. The results account for power broadening. Rabi splitting of signals, and power-induced extra resonances, the latter being related to the pure dephasing-induced resonances in the weak-field limit. The method can be applied to a large no. of multiple resonant nonlinear spectroscopies, esp. CARS, CSRS, coherent Rayleigh scattering and sum- or difference-frequency generation

The Perfect Policeman: Colonial Policing, Modernity and Conscience on Sumatra’s West Coast in the early 1930s

Page range: 165-193This article aims to show how studying the colonial police in the Dutch East-Indies—in this case, a political policeman of Minangkabau origin, working in the west coast of Sumatra during the 1920s–1930s—can further our understanding of both the functioning of the colonial state and the multiple meanings of modernity and radicalism in colonial society. The essay explores the ways in which the writings of a particular policeman, Roesad gelar Soetan Perpatih, illuminate the concepts of civilization, modernity, and political progress that circulated and functioned in the late-colonial state. By moving the perspective from Indonesians being policed to Indonesian policemen, the article addresses the fact that the local search for progress and modernity did not only entail anticolonial nationalism or radicalism, but could also imply that the person searching would become involved in colonial politics. This also implied—as the Roesad’s case makes clear—becoming entangled in the contradictions of (racial) difference and (interdependent) involvement that characterized the colonial state

Magnetic resonance imaging (MRI) of heavy-metal transport and fate in an artificial biofilm

Unlike planktonic systems, reaction rates in biofilms are often limited by mass transport, which controls the rate of supply of contaminants into the biofilm matrix. To help understand this phenomenon, we investigated the potential of magnetic resonance imaging (MRI) to spatially quantify copper transport and fate in biofilms. For this initial study we utilized an artificial biofilm composed of a 50:50 mix of bacteria and agar. MRI successfully mapped Cu2+ uptake into the artificial biofilm by mapping T2 relaxation rates. A calibration protocol was used to convert T2 values into actual copper concentrations. Immobilization rates in the artificial biofilm were slow compared to the rapid equilibration of planktonic systems. Even after 36 h, the copper front had migrated only 3 mm into the artificial biofilm and at this distance from the copper source, concentrations were very low. This slow equilibration is a result of (1) the time it takes copper to diffuse over such distances and (2) the adsorption of copper onto cell surfaces, which further impedes copper diffusion. The success of this trial run indicates MRI could be used to quantitatively map heavy metal transport and immobilization in natural biofilms

A CRITICAL STUDY IN THE COMPLEX-POLYMORPHOUS GENUS SCHIMA (THEACEAE)

 1. The author considers the genus Schima monotypic. Its only species, Schima wallichii (DC.) Korth., is subdivided into nine geographically separated subspecies and three varieties.These may be recognised sometimes by one dominating chax*acter,mostly, however, by a complex of characters.Several new combinations are made.2. Yet the variability of most of the subspecies is still often enormous and at first sight appears complex. Thus we may often encounter the polymorphy of the whole species in its subspecies again. It was the striking different percentage-numbers of(phenotypically) about the same characters which turned the scale in favour of the recognition of the subspecies, besides their geographic separation.The attempts made by the author to divide certain resulting complex-polymorphous subspecies into units of still lower rank and to trace correlations with peculiarities of environment such as different heights above sealevel, or with different stages in the age of the trees, failed. 3. On account of these negative results and the above mentioned different percentage-numbers for phenotypically about the same characters, the author came to the conclusion that the most probable explanation is that the variability within the subspecies is just due to Mendel-segregation and nothing else.It looks very much as if one is dealing here with the inheriting of striking characters, each caused by one or only a few polymeric factors, characters which hold their own, just as in panmictlcally propagated populations (by cross-pollination). This explanation, too,makes the striking fact that in some subspecies we find back phenotypically the whole, or part, of the polymorphy of the entire species more understandable, as well as the fact that individuals of different subspecies may agree phenotypically, whereas genotypically they belong to different races (subspecies), Moreover, all these phenomena strongly support the monotypic conception of the genus. 4. The author saw few examples from the area outside Indonesia. However,this does neither influence his monotypic conception of the genus, nor his method of dividing it into units of lower ranks. The study of the scanty amount of specimens,literature, and the drawings seen appeared more than sufficiently convincing. Yet he is not quite certain whether the correct rank was ascribed to some of the lower taxa involved. It would perhaps have been advisable to consider the variety superba and the continental parts of the subspecies oblata and monticola as distinct subspecies.Future consideration of this matter shall have to decide

Dielectric breakdown induced by picosecond laser pulses

The damage thresholds of transparent optical materials were investigated. Single picosecond pulses at 1.06 microns, 0.53 microns and 0.35 microns were obtained from a mode locked Nd-YAG oscillator-amplifier-frequency multiplier system. The pulses were Gaussian in space and time and permitted the determination of breakdown thresholds with a reproducibility of 15%. It was shown that the breakdown thresholds are characteristic of the bulk material, which included nine alkali halides, five different laser host materials, KDP, quartz, sapphire and calcium fluoride. The extension of the damage data to the ultraviolet is significant, because some indication was obtained that two- and three-photon absorption processes begin to play a role in determining the threshold. Throughout the visible region of the spectrum the threshold is still an increasing function of frequency, indicating that avalanche ionization is the dominant factor in determining the breakdown threshold. This was confirmed by a detailed study of the damage morphology with a high resolution microscope just above the threshold. The influence of self focusing is discussed, and evidence for beam distortion below the power threshold for complete self focusing is presented, confirming the theory of Marburger