Effective capillary interaction of spherical particles at fluid interfaces

We present a detailed analysis of the effective force between two smooth spherical colloids floating at a fluid interface due to deformations of the interface. The results hold in general and are applicable independently of the source of the deformation provided the capillary deformations are small so that a superposition approximation for the deformations is valid. We conclude that an effective long--ranged attraction is possible if the net force on the system does not vanish. Otherwise, the interaction is short--ranged and cannot be computed reliably based on the superposition approximation. As an application, we consider the case of like--charged, smooth nanoparticles and electrostatically induced capillary deformation. The resulting long--ranged capillary attraction can be easily tuned by a relatively small external electrostatic field, but it cannot explain recent experimental observations of attraction if these experimental systems were indeed isolated.Comment: 23 page

Interplay between elastic fields due to gravity and a partial dislocation for a hard-sphere crystal coherently grown under gravity: driving force for defect disappearance

We previously observed that an intrinsic staking fault shrunk through a glide of a Shockley partial dislocation terminating its lower end in a hard-sphere crystal under gravity coherently grown in by Monte Carlo simulations [Mori et al., Molec. Phys. 105, 1377 (2007)]; it was an answer to a one-decade long standing question why the stacking disorder in colloidal crystals reduced under gravity [Zhu et al., Nature 387, 883 (1997)]. Here, we present an elastic energy calculation; in addition to the self-energy of the partial dislocation [Mori et al., Prog. Theor. Phys. Suppl. 178, 33 (2009)] we calculate the cross-coupling term between elastic field due to gravity and that due to a Shockley partial dislocation. The cross term is a increasing function of the linear dimension R over which the elastic field expands, showing that a driving force arises for the partial dislocation moving toward the upper boundary of a grain.Comment: 8pages, 4figures, to be published in Molecular Physic

Manipulation of Optimal Matchings via Predonation of Endowment

In this paper we answer a question posed by Sertel and Sanver (2002) on the manipulability of optimal matching rules in matching problems with endowments. We characterize the classes of consumption rules under which optimal matching rules can be manipulated via predonation of endowment.G. Fiestras-Janeiro received financial support from the Spanish Ministerio de Ciencia y Tecnología and the FEDER through projects PB98-0613-C02-02 and BEC2002-04102-C02-02, and from the Xunta de Galicia through grant PGIDT00PXI20703PN. The work of F. Klijn is partially supported by Research Grant BEC2002-02130 from the Spanish Ministerio de Ciencia y Tecnología and by a Marie Curie Fellowship of the European Community programme “Improving Human Research Potential and the Socioeconomic Knowledge Base” under contract number HPMF-CT-2001-01232. The work of E. Sánchez is supported by project BEC2002-04102-C02-02 from the Spanish Ministerio de Ciencia y Tecnología and the FEDER

Emission Spectrum of a Dipole in a Semi-infinite Periodic Dielectric Structure: Effect of the Boundary

The emission spectrum of a dipole embedded in a semi-infinite photonic crystal is calculated. For simplicity we study the case in which the dielectric function is sinusoidally modulated only along the direction perpendicular to the boundary surface plane. In addition to oscillations of the emission rate with the distance of the dipole from the interface we also observed that the shape of the emission spectrum srongly depends on the \em initial \em phase of the dielectric modulation. When the direction of light propagation inside the periodic structure is not normal to the boundary surface plane we observed aditional singularities in the emission spectrum, which arise due to different angle-dependence of the Bragg stop-band for $TE$ and $TM$ polarizations.Comment: 14 pages, 6 figures, to appear in Phys Rev

Ordered droplet structures at the liquid crystal surface and elastic-capillary colloidal interactions

We demonstrate a variety of ordered patterns, including hexagonal structures and chains, formed by colloidal particles (droplets) at the free surface of a nematic liquid crystal (LC). The surface placement introduces a new type of particle interaction as compared to particles entirely in the LC bulk. Namely, director deformations caused by the particle lead to distortions of the interface and thus to capillary attraction. The elastic-capillary coupling is strong enough to remain relevant even at the micron scale when its buoyancy-capillary counterpart becomes irrelevant.Comment: 10 pages, 3 figures, to be published in Physical Review Letter

Resonance-Induced Effects in Photonic Crystals

For the case of a simple face-centered-cubic photonic crystal of homogeneous dielectric spheres, we examine to what extent single-sphere Mie resonance frequencies are related to band gaps and whether the width of a gap can be enlarged due to nearby resonances. Contrary to some suggestions, no spectacular effects may be expected. When the dielectric constant of the spheres $\epsilon_s$ is greater than the dielectric constant $\epsilon_b$ of the background medium, then for any filling fraction $f$ there exists a critical $\epsilon_c$ above which the lowest lying Mie resonance frequency falls inside the lowest stop gap in the (111) crystal direction, close to its midgap frequency. If $\epsilon_s <\epsilon_b$, the correspondence between Mie resonances and both the (111) stop gap and a full gap does not follow such a regular pattern. If the Mie resonance frequency is close to a gap edge, one can observe a resonance-induced widening of a relative gap width by $\approx 5$.Comment: 14 pages, 3 figs., RevTex. For more info look at http://www.amolf.nl/external/wwwlab/atoms/theory/index.htm

Challenges of poor surface water drainage and wastewater management in refugee camps

Since refugee camps are meant to be temporary and setting them up usually require urgency, little attention has been given to provision of surface water drainage and to a lesser extent wastewater management. As the population of refugees in these camps continues to grow, the effectiveness of drainage infrastructure continues to diminish. In addition, availability of sufficient safe drinking water and wastewater management have become difficult in the refugee camps across the world. The present situation in refugee camps across the world, such as flooding and outbreak of water-related diseases in South Sudan refugee camps, has made the need for sustainable approach to solving the problems to be very urgent. One sustainable way of solving the problems of flooding and outbreak of diseases in refugee camps is to provide effective drainage and wastewater infrastructure that ensures all the wastewater are properly collected, treated and reused for various purposes such as agriculture, drinking, laundry and other relevant uses. This paper therefore presents the current state of drainage and wastewater management in two refugee camps and propose low-cost technologies for stormwater management, wastewater collection, treatment and potential reuse, suitable for these refugee camps

Multi-product inventory managmement model with a multiple periodicity

Inventory management is of great interest to various spheres of activity. This theory is a new industry that arose in connection with the need of optimal regulation of reserves. Over the past decades, significant progress has been made in the development of various mathematical models for managing commodity and noncommodity inventories. Despite the fact that this topic is quite popular in the literature, the question of purchasing resources in conditions of their deficit remains topical. The study is devoted to the development of a multi-product inventory management model with a multiple periodicity

Conservation genomic analysis of domestic and wild pig populations from the Iberian Peninsula

Abstract Background Inbreeding is among the major concerns in management of local livestock populations. The effective population size of these populations tends to be small, which enhances the risk of fitness reduction and extinction. High-density SNP data make it possible to undertake novel approaches in conservation genetics of endangered breeds and wild populations.A total of 97 representative samples of domestic and wild pig populations from the Iberian Peninsula, subjected to different levels of threat with extinction, were genotyped with a 60 K SNP panel. Data analyses based on: (i) allele frequency differences; (ii) linkage disequilibrium and (iii) runs of homozygosity were integrated to study population relationships, inbreeding and demographic history. Results The domestic pigs analyzed belonged to local Spanish and Portuguese breeds: Iberian ─ including the variants Retinto Iberian, Negro Iberian and Manchado de Jabugo ─, Bisaro and Chato Murciano. The population structure and persistence of phase analysis suggested high genetic relations between Iberian variants, with recent crossbreeding of Manchado de Jabugo with other pig populations. Chato Murciano showed a high frequency of long runs of homozygosity indicating recent inbreeding and reflecting the recent bottleneck reported by historical records. The Chato Murciano and the Manchado de Jabugo breeds presented the lowest effective population sizes in accordance with their status of highly inbred breeds. The Iberian wild boar presented a high frequency of short runs of homozygosity indicating past small population size but no signs of recent inbreeding. The Iberian breed showed higher genetic similarities with Iberian wild boar than the other domestic breeds. Conclusions High-density SNP data provided a consistent overview of population structure, demographic history and inbreeding of minority breeds and wild pig populations from the Iberian Peninsula. Despite the very different background of the populations used, we found a good agreement between the different analyses. Our results are also in agreement with historical reports and provide insight in the events that shaped the current genetic variation of pig populations from the Iberian Peninsula. The results exposed will aid to design and implement strategies for the future management of endangered minority pig breeds and wild populations.This project was financially supported by European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant #ERC-2009-AdG: 249894 (Sel Sweep project).Peer Reviewe