Dissipative Effects in Odd Viscous Stokes Flow around a Single Sphere.

Odd viscosity (OV) is a transport coefficient in, for example, fluids of self-spinning (active) particles or electrons in an external magnetic field. The key feature of OV is that it does not contribute to dissipation in two spatial dimensions. In contrast, we explicitly show that in the three-dimensional case, OV can contribute indirectly to dissipation by modifying the fluid flow.

Seeded stimulated X-ray emission at 5.9 keV.

X-ray free-electron lasers (XFELs) provide intense pulses that can generate stimulated X-ray emission, a phenomenon that has been observed and studied in materials ranging from neon to copper. Two schemes have been employed: amplified spontaneous emission (ASE) and seeded stimulated emission (SSE), where a second color XFEL pulse provides the seed. Both phenomena are currently explored for coherent X-ray laser sources and spectroscopy.

Nematronics: Reciprocal Coupling between Ionic Currents and Nematic Dynamics.

Adopting a spintronics-inspired approach, we study the reciprocal coupling between ionic charge currents and nematic texture dynamics in a uniaxial nematic electrolyte. Assuming quenched fluid dynamics, we develop equations of motion analogously to spin torque and spin pumping. Based on the principle of least dissipation of energy, we derive the adiabatic "nematic torque" exerted by ionic currents on the nematic director field as well as the reciprocal motive force on ions due to the orientational dynamics of the director.

Realization of the Brazil-nut effect in charged colloids without external driving.

Sedimentation is a ubiquitous phenomenon across many fields of science, such as geology, astrophysics, and soft matter. Sometimes, sedimentation leads to unusual phenomena, such as the Brazil-nut effect, where heavier (granular) particles reside on top of lighter particles after shaking. We show experimentally that a Brazil-nut effect can be realized in a binary colloidal system of long-range repulsive charged particles driven purely by Brownian motion and electrostatics without the need for activity.

Anisotropic electrostatic screening of charged colloids in nematic solvents.

The physical behavior of anisotropic charged colloids is determined by their material dielectric anisotropy, affecting colloidal self-assembly, biological function, and even out-of-equilibrium behavior. However, little is known about anisotropic electrostatic screening, which underlies all electrostatic effective interactions in such soft or biological materials. In this work, we demonstrate anisotropic electrostatic screening for charged colloidal particles in a nematic electrolyte.

Topological-Defect-Induced Surface Charge Heterogeneities in Nematic Electrolytes.

We show that topological defects in an ion-doped nematic liquid crystal can be used to manipulate the surface charge distribution on chemically homogeneous, charge-regulating external surfaces, using a minimal theoretical model. In particular, the location and type of the defect encodes the precise distribution of surface charges and the effect is enhanced when the liquid crystal is flexoelectric. We demonstrate the principle for patterned surfaces and charged colloidal spheres.

Complex electric double layers in charged topological colloids.

Charged surfaces in contact with liquids containing ions are accompanied in equilibrium by an electric double layer consisting of a layer of electric charge on the surface that is screened by a diffuse ion cloud in the bulk fluid. This screening cloud determines not only the interactions between charged colloidal particles or polyelectrolytes and their self-assembly into ordered structures, but it is also pivotal in understanding energy storage devices, such as electrochemical cells and supercapacitors. However, little is known to what spatial complexity the electric double layers can be designed.

Flow-Induced Surface Charge Heterogeneity in Electrokinetics due to Stern-Layer Conductance Coupled to Reaction Kinetics.

We theoretically study the electrokinetic problem of a pressure-induced liquid flow through a narrow long channel with charged walls, going beyond the classical Helmholtz-Schmolukowski picture by considering the surprisingly strong combined effect of (i) Stern-layer conductance and (ii) dynamic charge-regulating rather than fixed surface charges. We find that the water flow induces, apart from the well-known streaming potential, also a strongly heterogeneous surface charge and zeta potential on chemically homogeneous channel walls. Moreover, we identify a novel steady state with a nontrivial 3D electric flux with 2D surface charges acting as sources and sinks.

Colloid-oil-water-interface interactions in the presence of multiple salts: charge regulation and dynamics.

We theoretically and experimentally investigate colloid-oil-water-interface interactions of charged, sterically stabilized, poly(methyl-methacrylate) colloidal particles dispersed in a low-polar oil (dielectric constant ε = 5-10) that is in contact with an adjacent water phase. In this model system, the colloidal particles cannot penetrate the oil-water interface due to repulsive van der Waals forces with the interface whereas the multiple salts that are dissolved in the oil are free to partition into the water phase. The sign and magnitude of the Donnan potential and/or the particle charge is affected by these salt concentrations such that the effective interaction potential can be highly tuned.

Tuning Colloid-Interface Interactions by Salt Partitioning.

We show that the interaction of an oil-dispersed colloidal particle with an oil-water interface is highly tunable from attractive to repulsive, either by varying the sign of the colloidal charge via charge regulation or by varying the difference in hydrophilicity between the dissolved cations and anions. In addition, we investigate the yet unexplored interplay between the self-regulated colloidal surface charge distribution with the planar double layer across the oil-water interface and the spherical one around the colloid. Our findings explain recent experiments and have direct relevance for tunable Pickering emulsions.

Alternating strings and clusters in suspensions of charged colloids.

We report the formation of alternating strings and clusters in a binary suspension of repulsive charged colloids with double layers larger than the particle size. Within a binary cell model we include many-body and charge-regulation effects under the assumption of a constant surface potential, and consider their repercussions on the two-particle interaction potential. We find that the formation of induced dipoles close to a charge-reversed state may explain the formation of these structures.

A Landau-de Gennes theory for hard colloidal rods: Defects and tactoids.

We construct a phenomenological Landau-de Gennes theory for hard colloidal rods by performing an order parameter expansion of the chemical-potential dependent grand potential. By fitting the coefficients to known results of Onsager theory, we are not only able to describe the isotropic-nematic phase transition as function of density, including the well-known density jump, but also the isotropic-nematic planar interface. The resulting theory is applied in calculations of the isotropic core size in a radial hedgehog defect, the density dependence of linear defects of hard rods in square confinement, and the formation of a nematic droplet in an isotropic background.

Does Practice Type Determine the Complexity of Patients Encountered for Orthognathic Surgery?

Purpose: This study sought to determine whether the type of oral and maxillofacial surgery (OMS) practice dictated the complexity of patients encountered for orthognathic surgery and to determine whether there were meaningful differences in comorbidities between patient groups.

Materials And Methods: This was a retrospective cohort study of orthognathic surgical patients operated on by surgeons at an academic medical center (AMC; OMS department at the University of Alabama-Birmingham) compared with a private practice (PP) group that also operated at the AMC auxiliary facility. Surgical procedures included in this study were Le Fort osteotomy, bilateral sagittal split osteotomy, genioplasty, and combinations of these procedures.

Density-induced reentrant melting of colloidal Wigner crystals.

Electrostatic repulsions can drive crystallization in many-particle systems. For charged colloidal systems, the phase boundaries as well as crystal structure are highly tunable by experimental parameters such as salt concentration and pH. By using projections of the colloid-ion mixture to a system of (soft) repulsive spheres and the one-component plasma (OCP), we study the hitherto unexplained experimentally observed reentrant melting of electrostatically repelling colloids upon increasing the colloid density.

Polio eradication in the World Health Organization African Region, 2008-2012.

A renewed commitment at the regional and the global levels led to substantial progress in the fight for polio eradication in the African Region (AFR) of the World Health Organization (WHO) during 2008-2012. In 2008, there were 912 reported cases of wild poliovirus (WPV) infection in 12 countries in the region. This number had been reduced to 128 cases in 3 countries in 2012, of which 122 were in Nigeria, the only remaining country with endemic circulation of WPV in AFR.

The role of older children and adults in wild poliovirus transmission.

As polio eradication inches closer, the absence of poliovirus circulation in most of the world and imperfect vaccination coverage are resulting in immunity gaps and polio outbreaks affecting adults. Furthermore, imperfect, waning intestinal immunity among older children and adults permits reinfection and poliovirus shedding, prompting calls to extend the age range of vaccination campaigns even in the absence of cases in these age groups. The success of such a strategy depends on the contribution to poliovirus transmission by older ages, which has not previously been estimated.

Announcing Swine Flu and the Interpretation of Pandemic Anxiety.

This paper discusses the ways in which 2009 novel swine-origin influenza A (H1N1) was announced and resonated with current pandemic anxieties. In particular, the US Centers for Disease Control and Prevention (CDC) are used as a lens through which recent pandemic anxieties can be analysed and understood. This entails a closer look at the securitisation of public health and the challenges and struggles this may have caused within public health agencies.

An outbreak of wild poliovirus in the Republic of Congo, 2010-2011.

Background: The Republic of Congo has had no cases of wild poliovirus type 1 (WPV1) since 2000. In October 2010, a neurologist noted an abnormal number of cases of acute flaccid paralysis (AFP) among adults, which were later confirmed to be caused by WPV1.

Methods: Those presenting with AFP underwent clinical history, physical examination, and clinical specimen collection to determine if they had polio.

A stereoselectively deuterated supramolecular motif to probe the role of solvent during self-assembly processes.

Small changes in the alkane solvent structure in combination with temperature effects lead to four different conformations of stereoselectively deuterated benzene-1,3,5-tricarboxamides in the aggregated state, affecting the expression of the supramolecular chirality and highlighting the role of the solvent structure in self-assembly processes.

Family-Based Interventions Targeting Childhood Obesity: A Meta-Analysis.

Background: With the rising prevalence of childhood obesity over the last several decades, and the call for more family-based intervention research to combat childhood obesity, it is important to examine the extant research on family-based interventions in order to make recommendations and improve future research.

Objective: To conduct a meta-analysis of family-based interventions targeting childhood obesity in the last decade in order to inform the research in the next decade.

Methods: A literature review was conducted between December 2009-April 2010.

Dynamic supramolecular polymers based on benzene-1,3,5-tricarboxamides: the influence of amide connectivity on aggregate stability and amplification of chirality.

N-Centred benzene-1,3,5-tricarboxamides (N-BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid-state behaviour and self-assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X-ray diffraction revealed that the chiral N-BTA derivatives with branched 3,7-dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Col(ho). In contrast, N-BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds.

Influence of connection geometry on dynamic micromotion at the implant-abutment interface.

The aim of this study was to evaluate dynamic micromotion at the implant-abutment interface for 3 different implant neck designs. Five samples each from 3 implant types with different neck designs were subjected to 1 x 10(6) cycles under simulated oral conditions. Load magnitudes varied from 10 to 250 N at 15 Hz.