Proton NMR relaxometry as a useful tool to evaluate swelling processes in peat soils

Dramatic physical and physico-chemical changes in soil properties may arise due to temperature and moisture variations as well as swelling of soil organic matter (SOM) under constant conditions. Soil property variations may influence sorption/desorption and transport processes of environmental contaminants and nutrients in natural-organic-matterrich soils. Notwithstanding the studies reported in literature, a mechanistic model for SOM swelling is unavailable yet. The objective of the present study was the evaluation of the swelling of peat soils, considered as SOM models, by 1H NMR relaxometry and differential scanning calorimetry (DSC). Namely, information on the processes governing physical and physicochemical changes of peat during re-hydration were collected. The basic hypothesis of the present study was that the changes are slow and may affect water state as well as amounts of different water types into the peats. For this reason, such changes can be evidenced through the variations of mobility and thermal behaviour of the involved H2O molecules by using 1H NMR relaxometry and DSC. According to the experimental results, a mechanistic model, describing the fundamental processes of peat swelling, was obtained. Two different peats re-wetted at three temperatures were used. The swelling process was monitored by measuring spin-spin relaxation time (T2) over a hydration time of several months. Moreover, DSC, T1 – T2 and T2 – D correlation measurements were done at the beginning and at the end of the hydration. Supplementary investigations were also done in order to discriminate between the swelling effects and the contributions from soil solution, internal magnetic field gradients and/or soil microorganisms to proton relaxation. All the results revealed peat swelling. It was evidenced by pore size distribution changes, volumetric expansion and redistribution of water, increasing amounts of nonfreezable and loosely bound water, as well as formation of gel phases and reduction of the translational and rotational mobility of H2O molecules. All the findings implied that changes of the physical and physicochemical properties of peats were obtained. In particular, three different processes having activation energies comprised in the interval 5 – 50 kJ mol-1 were revealed. The mechanistic model which was, then, developed included water reorientation in bound water phases, water diffusion into the peat matrix and reorientation of SOM chains as fundamental processes governing SOM swelling. This study is of environmental significance in terms of re-naturation and re-watering of commercially applied peatlands and of sorption/desorption and transport processes of pollutants and nutrients in natural organic matter rich soil

Applications of thermal energy storage in the cement industry

In the manufacture of cement, literally trillions of Btu's are rejected to the environment each year. The purpose of this feasibility study program was to determine whether thermal energy storage could be used to conserve or allow alternative uses of this rejected energy. This study identifies and quantifies the sources of rejected energy in the cement manufacturing process, established use of this energy, investigates various storage system concepts, and selects energy conservation systems for further study. Thermal performance and economic analyses are performed on candidate storage systems for four typical cement plants representing various methods of manufacturing cement. Through the use of thermal energy storage in conjunction with waste heat electric power generation units, an estimated 2.4 x 10 to the 13th power Btu/year, or an equivalent on investment of the proposed systems are an incentive for further development

Metastability of a granular surface in a spinning bucket

The surface shape of a spinning bucket of granular material is studied using a continuum model of surface flow developed by Bouchaud et al. and Mehta et al. An experimentally observed central subcritical region is reproduced by the model. The subcritical region occurs when a metastable surface becomes unstable via a nonlinear instability mechanism. The nonlinear instability mechanism destabilizes the surface in large systems while a linear instability mechanism is relevant for smaller systems. The range of angles in which the granular surface is metastable vanishes with increasing system size.Comment: 8 pages with postscript figures, RevTex, to appear in Phys. Rev.

The Struggle for Palestinian Hearts and Minds: Violence and Public Opinion in the Second Intifada

This paper examines how violence in the Second Intifada influences Palestinian public opinion. Using micro data from a series of opinion polls linked to data on fatalities, we find that Israeli violence against Palestinians leads them to support more radical factions and more radical attitudes towards the conflict. This effect is temporary, however, and vanishes completely within 90 days. We also find some evidence that Palestinian fatalities lead to the polarization of the population and to increased disaffection and a lack of support for any faction. Geographically proximate Palestinian fatalities have a larger effect than those that are distant, while Palestinian fatalities in targeted killings have a smaller effect relative to other fatalities. Although overall Israeli fatalities do not seem to affect Palestinian public opinion, when we divide those fatalities by the different factions claiming responsibility for them, we find some evidence that increased Israeli fatalities are effective in increasing support for the faction that claimed them.Israeli-Palestinian conflict, fatalities, public opinion

Optimal Dynamical Decoherence Control of a Qubit

A theory of dynamical control by modulation for optimal decoherence reduction is developed. It is based on the non-Markovian Euler-Lagrange equation for the energy-constrained field that minimizes the average dephasing rate of a qubit for any given dephasing spectrum.Comment: 6 pages, including 2 figures and an appendi

Optoelectronic Reservoir Computing

Reservoir computing is a recently introduced, highly efficient bio-inspired approach for processing time dependent data. The basic scheme of reservoir computing consists of a non linear recurrent dynamical system coupled to a single input layer and a single output layer. Within these constraints many implementations are possible. Here we report an opto-electronic implementation of reservoir computing based on a recently proposed architecture consisting of a single non linear node and a delay line. Our implementation is sufficiently fast for real time information processing. We illustrate its performance on tasks of practical importance such as nonlinear channel equalization and speech recognition, and obtain results comparable to state of the art digital implementations.Comment: Contains main paper and two Supplementary Material

Experimental Violation of Bell's Inequality in Spatial-Parity Space

We report the first experimental violation of Bell's inequality in the spatial domain using the Einstein--Podolsky--Rosen state. Two-photon states generated via optical spontaneous parametric downconversion are shown to be entangled in the parity of their one-dimensional transverse spatial profile. Superpositions of Bell states are prepared by manipulation of the optical pump's transverse spatial parity--a classical parameter. The Bell-operator measurements are made possible by devising simple optical arrangements that perform rotations in the one-dimensional spatial-parity space of each photon of an entangled pair and projective measurements onto a basis of even--odd functions. A Bell-operator value of 2.389 +- 0.016 is recorded, a violation of the inequality by more than 24 standard deviations.Comment: 10 pages, 3 figures, 1 Tabl

Stealing bandwidth from BitTorrent seeders

BitTorrent continues to comprise the largest fraction of Internet traffic. While significant progress has been made in understanding the BitTorrent choking mechanism, its security vulnerabilities have not been investigated thoroughly. This paper presents an experimental analysis of bandwidth attacks against different choking algorithms in the BitTorrent seed state. We reveal a simple exploit that allows malicious peers to receive a considerably higher download rate than contributing leechers, therefore introducing significant efficiency degradations for benign peers. We show the damage caused by the proposed attack in two different environments: a lab testbed comprising 32 peers and a PlanetLab testbed with 300 peers. Our results show that 3 malicious peers can degrade the download rate up to 414.99% for all peers. Combined with a Sybil attack that consists of as many attackers as leechers, it is possible to degrade the download rate by more than 1000%. We propose a novel choking algorithm which is immune against bandwidth attacks and a countermeasure against the revealed attack

Force correlations and arches formation in granular assemblies

In the context of a simple microscopic schematic scalar model we study the effects of spatial correlations in force transmission in granular assemblies. We show that the parameters of the normalized weights distribution function, $P(v)\sim v^{\alpha}\exp(-v/\phi)$, strongly depend on the spatial extensions, $\xi_V$, of such correlations. We show, then, the connections between measurable macroscopic quantities and microscopic mechanisms enhancing correlations. In particular we evaluate how the exponential cut-off, $\phi(\xi_V)$, and the small forces power law exponent, $\alpha(\xi_V)$, depend on the correlation length, $\xi_V$. If correlations go to infinity, weights are power law distributed.Comment: 6 page