Epistemic Protocols for Distributed Gossiping

Gossip protocols aim at arriving, by means of point-to-point or group communications, at a situation in which all the agents know each other's secrets. We consider distributed gossip protocols which are expressed by means of epistemic logic. We provide an operational semantics of such protocols and set up an appropriate framework to argue about their correctness. Then we analyze specific protocols for complete graphs and for directed rings.Comment: In Proceedings TARK 2015, arXiv:1606.0729

Health risks of irrigation with untreated urban wastewater in the southern Punjab, Pakistan

Irrigation water / Water quality / Water reuse / Waste waters / Risks / Public health / Diseases / Farmers / Pakistan / Southern Punjab / Haroonabad

Optimal linear estimation and data fusion

©2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Optimal mean square linear estimators are determined for general uncorrelated noise. We allow the noise variance matrix in the observation process to be singular. This requires properties of generalized inverses which are developed in Section II. The proofs appear to be new. When there are two observation sequences the optimal method of recursively fusing the two is determined. We derive a new formula for the covariance of the two estimates which then provides exact dynamics for a fused estimate.Elliott, R.J. ; van der Hoek, J

Picosecond fluorescence of intact and dissolved PSI-LHCI crystals

Over the last years many crystal structures of photosynthetic pigment-protein complexes have been determined, and used extensively to model spectroscopic results obtained on the same proteins in solution. However, the crystal structure is not necessarily identical to the structure of the protein in solution. Here we studied picosecond fluorescence of Photosystem I-Light Harvesting Complex I (PSI-LHCI), a multisubunit pigment protein complex that catalyzes the first steps of photosynthesis. The ultrafast fluorescence of PSI-LHCI crystals is identical to that of dissolved crystals, but differs considerably from most kinetics presented in literature. In contrast to most studies, the present data can be modeled quantitatively with only 2 compartments: PSI core and LHCI. This yields the rate of charge separation from an equilibrated core (22.5+/-2.5 ps) and rates of excitation energy transfer from LHCI to core (kLC) and vice versa (kCL). The ratio R=kCL/kLC between these rates appears to be wavelength-dependent and scales with the ratio of the absorption spectra of LHCI and core, indicating the validity of a detailed balance relation between both compartments. kLC depends slightly but non systematically on detection wavelength, averaging (9.4+/-4.9 ps)(-1). R ranges from 0.5 (below 690 nm) to around 1.3 above 720 nm

A deterministic discretisation-step upper bound for state estimation via Clark transformations

Copyright © 2004 Hindawi Publishing CorporationWe consider the numerical stability of discretisation schemes for continuous-time state estimation filters. The dynamical systems we consider model the indirect observation of a continuous-time Markov chain. Two candidate observation models are studied. These models are (a) the observation of the state through a Brownian motion, and (b) the observation of the state through a Poisson process. It is shown that for robust filters (via Clark's transformation), one can ensure nonnegative estimated probabilities by choosing a maximum grid step to be no greater than a given bound. The importance of this result is that one can choose an a priori grid step maximum ensuring nonnegative estimated probabilities. In contrast, no such upper bound is available for the standard approximation schemes. Further, this upper bound also applies to the corresponding robust smoothing scheme, in turn ensuring stability for smoothed state estimates.W. P. Malcolm, R. J. Elliott, and J. van der Hoe

Potential and Constraints for Animal Feed as an Objective of Poor Farmers in Participatory Research with Multipurpose Forage Crops in Central-America

Multipurpose forage crops can play an important role in improving the environmental and socio- economic sustainability of smallholder production systems in fragile environments. However, since the forage technology development framework has not been sufficiently applicable for poor farmers, adoption of especially legumes has been generally low (Peters et al., 2001). In a participatory research effort with smallholder farmers in Honduras focused at forage based technologies, food security turned out to be the main selection criterion whereas animal feed was secondary. Since animal feed related activities (farmer-led forage seed systems, production of dry season feed) have been identified as promising income generating options for poor farmers in the hillsides of Central-America, a further analysis was carried out to identify the (mainly household related) factors inducing or inhibiting farmers to opt for production of animal feed

Use of untreated wastewater in peri-urban agriculture in Pakistan: risks and opportunities

Water reuse / Waste waters / Water quality / Groundwater / Irrigation practices / Soil properties / Environmental effects / Conjunctive use / Pakistan / Haroonabad

Covalent effects in molecule-surface charge exchange: oxygen on silver(111)

The formation of neg. charged ions (O2-, O-) in the scattering of oxygen from silver surfaces is difficult to explain with the Brako-Newns scheme. Extended-Hueckel tight-binding calcns. are performed on model Ag(111) slabs, placing O2 adsorbates at various sites and mol. orientations. As the survival probability of a neg. charged ion leaving the surface is detd. by the back-tunneling frequency, the mol. ion survival probably should increase as the O2-Ag interaction decreases, and vice versa. On the other hand, the dissocn. probability will increase with increasing interaction strength. The strength of the O2-Ag interaction can be gaged by the dispersion found in the projected d. of states of the O2 affinity level 1pg. The second moment serves as a measure of relative dispersion, and in addn., can be related to the tunneling frequency. The bridging and hollow sites have the strongest O2-Ag interaction, thus the lowest survival probability of neg. ions and the highest degree of dissocn. The interaction at top sites is much less. These results can be used to explain the higher O-/(O- + O2-) ratio obsd. at more grazing incident beam angle

Covalent effects in molecule-surface charge exchange: oxygen on silver(111)

The formation of neg. charged ions (O2-, O-) in the scattering of oxygen from silver surfaces is difficult to explain with the Brako-Newns scheme. Extended-Hueckel tight-binding calcns. are performed on model Ag(111) slabs, placing O2 adsorbates at various sites and mol. orientations. As the survival probability of a neg. charged ion leaving the surface is detd. by the back-tunneling frequency, the mol. ion survival probably should increase as the O2-Ag interaction decreases, and vice versa. On the other hand, the dissocn. probability will increase with increasing interaction strength. The strength of the O2-Ag interaction can be gaged by the dispersion found in the projected d. of states of the O2 affinity level 1pg. The second moment serves as a measure of relative dispersion, and in addn., can be related to the tunneling frequency. The bridging and hollow sites have the strongest O2-Ag interaction, thus the lowest survival probability of neg. ions and the highest degree of dissocn. The interaction at top sites is much less. These results can be used to explain the higher O-/(O- + O2-) ratio obsd. at more grazing incident beam angle

Alternate wet/dry irrigation in rice cultivation: a practical way to save water and control malaria and Japanese encephalitis?

Water management / Water scarcity / Water use efficiency / Water conservation / Irrigated farming / Waterborne diseases / Rice / Malaria / Disease vectors / Productivity / Flood irrigation / Environmental control / Climate / China / East Africa / India / Indonesia / Japan / Philippines / Portugal / USA