Hydrodynamic coupling and rotational mobilities near planar elastic membranes

We study theoretically and numerically the coupling and rotational hydrodynamic interactions between spherical particles near a planar elastic membrane that exhibits resistance towards shear and bending. Using a combination of the multipole expansion and Faxen's theorems, we express the frequency-dependent hydrodynamic mobility functions as a power series of the ratio of the particle radius to the distance from the membrane for the self mobilities, and as a power series of the ratio of the radius to the interparticle distance for the pair mobilities. In the quasi-steady limit of zero frequency, we find that the shear- and bending-related contributions to the particle mobilities may have additive or suppressive effects depending on the membrane properties in addition to the geometric configuration of the interacting particles relative to the confining membrane. To elucidate the effect and role of the change of sign observed in the particle self and pair mobilities, we consider an example involving a torque-free doublet of counterrotating particles near an elastic membrane. We find that the induced rotation rate of the doublet around its center of mass may differ in magnitude and direction depending on the membrane shear and bending properties. Near a membrane of only energetic resistance toward shear deformation, such as that of a certain type of elastic capsules, the doublet undergoes rotation of the same sense as observed near a no-slip wall. Near a membrane of only energetic resistance toward bending, such as that of a fluid vesicle, we find a reversed sense of rotation. Our analytical predictions are supplemented and compared with fully resolved boundary integral simulations where a very good agreement is obtained over the whole range of applied frequencies.Comment: 14 pages, 7 figures. Revised manuscript resubmitted to J. Chem. Phy

Modeling near-field radiative heat transfer from sharp objects using a general 3d numerical scattering technique

We examine the non-equilibrium radiative heat transfer between a plate and finite cylinders and cones, making the first accurate theoretical predictions for the total heat transfer and the spatial heat flux profile for three-dimensional compact objects including corners or tips. We find qualitatively different scaling laws for conical shapes at small separations, and in contrast to a flat/slightly-curved object, a sharp cone exhibits a local \emph{minimum} in the spatially resolved heat flux directly below the tip. The method we develop, in which a scattering-theory formulation of thermal transfer is combined with a boundary-element method for computing scattering matrices, can be applied to three-dimensional objects of arbitrary shape.Comment: 5 pages, 4 figures. Corrected background information in the introduction, results and discussion unchange

Thermal performance evaluation of a low-cost housing prototype made with plywood panels in Southern Brazil

a b s t r a c t Although the Brazilian Federal Government has been increasing investments in the housing sector since 2004, there has been a significant increase in the housing deficit as well. In 2007 this deficit had already reached 7.2 million dwellings. The majority (84%) consists of families with monthly income under three minimum wages. However, none of the traditional lines of credit considers families up to that monthly income level for building their own dwellings. In 2004, a program was created to subsidize low-cost housing (''Programa de Subsídio à Habitação de Interesse Social -PSH") with a maximum subsidy of about US$ 2500 for the construction of 'do-it-yourself' units. The present research had the general purpose of conceiving, constructing and evaluating the performance of a low-cost prototype consisting of wood and plywood panels. The object of analysis in this case study was a building prototype located in Canoinhas, in the South of Brazil (26°10 0 38 00 S, altitude 765 m above sea level), which was built within the scope of a program for subsidized low-cost housing. The present paper is concerned with evaluating the thermal performance of the finished prototype by means of onsite measurements and performing computer simulations for testing improvements of the original building prototype. From obtained results, general guidelines were drawn for improving indoor comfort conditions

Guidelines for initiation of anti-tumour necrosis factor therapy in rheumatoid arthritis: similarities and differences across Europe.

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Vorgehen bei der Bewertung der Archivfunktion von naturnahen und anthropogenen Böden im Kreis Recklinghausen

Für den Kreis Recklinghausen (Nordrhein-Westfalen) mit einer Fläche von etwa 761 km2 ist eine Bewertung ausgewählter Teilfunktionen gemäß BBodSchG zu erstellen. Neben dem naturnahen Außenbereich (450 km2) ist dabei soweit möglich auch der Siedlungsbereich zu berücksichtigen. Als zukünftige Planungsgrundlage entsteht abschließend eine zusammenfassende digitale Karte zur Bodenfunktionsbewertung. In dieser nimmt die Archivfunktion eine zentrale Rolle ein. Die Erstellung der Bodenfunktionskarten erfolgt in erster Linie auf Basis vorhandener digitaler Daten unter Verwendung der Software ArcGIS (Version 10.3). Von zentraler Bedeutung sind dabei die digitale Bodenkarte im Maßstab 1:50.000, die für Teilgebiete vorliegenden digitalen bzw. analogen Bodenkarten 1:5.000 und für landwirtschaftliche Flächen die auf der Bodenschätzung basierende DGK5 Boden. Ergänzend erfolgte eine bodenkundliche Untersuchungskampagne, die vor Ort insbesondere der Klärung von Widersprüchen zwischen Darstellungen verschiedener Bodenkarten und der Erfassung bislang fehlender Informationen dient. Als Kriterien zur Bewertung der Archivfunktion fließen die Naturnähe, die Regenerierbarkeit und die auf das Kreisgebiet bezogene Seltenheit ein. Da sich deren Bewertung im Wesentlichen auf das Merkmal „Bodentyp“ konzentriert, geht die Klassifizierung der oben genannten Kriterien zur Verdeutlichung von Unterschieden von einer 3-stufige Skala aus. Die Kriterien werden stufenweise in Matrices verrechnet. Die Seltenheit fließt mit einer Gewichtung von 50 % ein. Rechnerisch ergibt sich letztlich eine fünfstufige Skala, wie sie in der Regel auch bei den weiteren betrachteten Teilfunktionen angestrebt wird. Bei der abschließenden Plausibilitätsprüfung wird im Einzelfall das Prinzip der Priorisierung und der Vergabe von Zu- bzw. Abschlägen angewandt. Hierbei wird auf ergänzende bodenrelevante Datengrundlagen zurückgegriffen (z.B. Bodendenkmale und Geotope). Die nach Konvertierung auch für die Plattform MapInfo nutzbare digitale Karte der Bewertung der Archivfunktion zeigt, dass der Anteil der Böden mit sehr hoher Wertigkeit (Wertestufen > 4) im naturnahen Außenbereich bei etwa 5 % (ca. 24 km2) liegt. Dabei handelt es sich insbesondere um Plaggenesch und Niedermoor im Bereich der Gebiete bei Dorsten und Haltern. Hinzu kommen 65 Teilflächen im Siedlungsbereich, in denen Schutzobjekte kartiert sind; diese entsprechen einem Flächenanteil von insgesamt 0,15 % (0,7 km²)

Disorder Potentials near Lithographically Fabricated Atom Chips

We show that previously observed large disorder potentials in magnetic microtraps for neutral atoms are reduced by about two orders of magnitude when using atom chips with lithographically fabricated high quality gold layers. Using one dimensional Bose-Einstein condensates, we probe the remaining magnetic field variations at surface distances down to a few microns. Measurements on a 100 um wide wire imply that residual variations of the current flow result from local properties of the wire.Comment: submitted on September 24th, 200

Maximally-localized Wannier Functions in Antiferromagnetic MnO within the FLAPW Formalism

We have calculated the maximally-localized Wannier functions of MnO in its antiferromagnetic (AFM) rhombohedral unit cell, which contains two formula units. Electron Bloch functions are obtained with the linearized augmented plane-wave method within both the LSD and the LSD+U schemes. The thirteen uppermost occupied spin-up bands correspond in a pure ionic scheme to the five Mn 3d orbitals at the Mn_1 (spin-up) site, and the four O 2s/2p orbitals at each of the O_1 and O_2 sites. Maximal localization identifies uniquely four Wannier functions for each O, which are trigonally-distorted sp^3-like orbitals. They display a weak covalent bonding between O 2s/2p states and minority-spin d states of Mn_2, which is absent in a fully ionic picture. This bonding is the fingerprint of the interaction responsible for the AFM ordering, and its strength depends on the one-electron scheme being used. The five Mn Wannier functions are centered on the Mn_1 site, and are atomic orbitals modified by the crystal field. They are not uniquely defined by the criterion of maximal localization and we choose them as the linear combinations which diagonalize the r^2 operator, so that they display the D_3d symmetry of the Mn_1 site.Comment: 11 pages, 6 PostScript figures. Uses Revtex4. Hi-res figures available from the author