Alfvén waves at low magnetic Reynolds number:transitions between diffusion, dispersive Alfvén waves and nonlinear propagation

We seek the conditions in which Alfvén waves (AW) can be produced in laboratory-scale liquid metal experiments, i.e. at low magnetic Reynolds Number (Rm). Alfvén waves are incompressible waves propagating along magnetic fields typically found in geophysical and astrophysical systems. Despite the high values of Rm in these flows, AW can undergo high dissipation in thin regions, for example in the solar corona where anomalous heating occurs (Davila, Astrophys. J., vol. 317, 1987, p. 514; Singh &amp; Subramanian, Sol. Phys., vol. 243, 2007, pp. 163–169). Understanding how AW dissipate energy and studying their nonlinear regime in controlled laboratory conditions may thus offer a convenient alternative to observations to understand these mechanisms at a fundamental level. Until now, however, only linear waves have been experimentally produced in liquid metals because of the large magnetic dissipation they undergo when Rm ≪ 1 and the conditions of their existence at low Rm are not understood. To address these questions, we force AW with an alternating electric current in a liquid metal in a transverse magnetic field. We provide the first mathematical derivation of a wave-bearing extension of the usual low-Rm magnetohydrodynamics (MHD) approximation to identify two linear regimes: the purely diffusive regime exists when Nω, the ratio of the oscillation period to the time scale of diffusive two-dimensionalisation by the Lorentz force, is small; the propagative regime is governed by the ratio of the forcing period to the AW propagation time scale, which we call the Jameson number Ja after (Jameson, J. Fluid Mech., vol. 19, issue 4, 1964, pp. 513–527). In this regime, AW are dissipative and dispersive as they propagate more slowly where transverse velocity gradients are higher. Both regimes are recovered in the FlowCube experiment (Pothérat &amp; Klein, J. Fluid Mech., vol. 761, 2014, pp. 168–205), in excellent agreement with the model up to Ja ≲ 0.85 but near the Ja = 1 resonance, high amplitude waves become clearly nonlinear. Hence, in electrically driving AW, we identified the purely diffusive MHD regime, the regime where linear, dispersive AW propagate, and the regime of nonlinear propagation.<br/

Fine mapping of X-linked clasped thumb and mental retardation (MASA syndrome) in Xq28

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66121/1/j.1399-0004.1994.tb04016.x.pd

Unified scaling of the structure and loading of nanoparticles formed via diffusion-limited coalescence

The present study establishes the scaling laws describing the structure of spherical nanoparticles formed by diffusion-limited coalescence. We produced drug-loaded nanoparticles from a poly(ethylene glycol)-poly(d,l-lactic acid) diblock polymer (PEG-b-PLA) by the nanoprecipitation method using different types of micromixing chambers to explore multiple mixing regimes and characteristic times. We first show that the drug loading of the nanoparticles is not controlled by the mixing time but solely by the drug-to-polymer ratio (D:P) in the feed and the hydrophobicity of the drug scaled via the partition coefficient P. We then procure compelling evidence that particles formed via diffusion/coalescence exhibit a relative distribution of PEG blocks between the particle core and its shell that depends only on mixing conditions (not on D:P). Scaling laws of PEG relative distribution and chain surface density were derived in different mixing regimes and showed excellent agreement with experimental data. In particular, results made evident that PEG blocks entrapment in the core of the particles occurs in the slow-mixing regime and favors the overloading (above the thermodynamic limit) of the particles with hydrophilic drugs. The present analysis compiles effective guidelines for the scale up of nanoparticles structure and properties with mixing conditions, which should facilitate their future translation to medical and industrial settings

Papatrónica – dispositivo de código abierto para la medición de golpes y prevención de daños mecánicos

En Argentina, según datos de la Secretaría de Agroindustria, se pierden y desperdician anualmente 14,5 millones de toneladas de alimentos en las etapas de producción, almacenamiento, transporte y procesamiento, siendo la cadena frutihortícola la que presenta mayor proporción de pérdidas. Los daños mecánicos generados por golpes ocasionan una parte importante de estas pérdidas, directamente como consecuencia de la ruptura de células y tejidos, e indirectamente por generar lesiones que permiten el ingreso de patógenos que producen necrosis o pudriciones

Papatrónica – dispositivo de código abierto para la medición de golpes y prevención de daños mecánicos

En Argentina, según datos de la Secretaría de Agroindustria, se pierden y desperdician anualmente 14,5 millones de toneladas de alimentos en las etapas de producción, almacenamiento, transporte y procesamiento, siendo la cadena frutihortícola la que presenta mayor proporción de pérdidas. Los daños mecánicos generados por golpes ocasionan una parte importante de estas pérdidas, directamente como consecuencia de la ruptura de células y tejidos, e indirectamente por generar lesiones que permiten el ingreso de patógenos que producen necrosis o pudriciones. El objetivo de este trabajo fue prototipar una plataforma abierta y modular de código abierto y bajo costo que permita determinar los puntos donde se producen golpes que puedan afectar los tubérculos de papa, pero también fácilmente adaptable a otros cultivos o productos, o a la medición de otras variables.Sociedad Argentina de Informática e Investigación Operativ

Identification and characterization of a human transthyretin variant

An apparent Mr variant of plasma transthyretin (TTR), previously detected using 2-D PAGE, is the first reported occurrence of this type of human TTR variant. We characterized the variant TTR to determine the nature of this difference. Comparative tryptic peptide maps of variant and normal TTR and sequencing of peptides which differed indicated the variant contained a single amino acid substitution of valine for tyrosine at position 116. Because such a change requires two nucleotide substitutions, we postulate the variant arose through mutation in codon 116 of a heretofore unrecognized polymorphic or rare variant allele of TTR.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26538/1/0000077.pd

Spontaneous shrinking of soft nanoparticles boosts their diffusion in confined media

Improving nanoparticles (NPs) transport across biological barriers is a significant challenge that could be addressed through understanding NPs diffusion in dense and confined media. Here, we report the ability of soft NPs to shrink in confined environments, therefore boosting their diffusion compared to hard, non-deformable particles. We demonstrate this behavior by embedding microgel NPs in agarose gels. The origin of the shrinking appears to be related to the overlap of the electrostatic double layers (EDL) surrounding the NPs and the agarose fibres. Indeed, it is shown that screening the EDL interactions, by increasing the ionic strength of the medium, prevents the soft particle shrinkage. The shrunken NPs diffuse up to 2 orders of magnitude faster in agarose gel than their hard NP counterparts. These findings provide valuable insights on the role of long range interactions on soft NPs dynamics in crowded environments, and help rationalize the design of more efficient NP-based transport systems.</p