Band-collision gel electrophoresis.

Electrophoretic mobility shift assays are widely used in gel electrophoresis to study binding interactions between different molecular species loaded into the same well. However, shift assays can access only a subset of reaction possibilities that could be otherwise seen if separate bands of reagent species might instead be collisionally reacted. Here, we adapt gel electrophoresis by fabricating two or more wells in the same lane, loading these wells with different reagent species, and applying an electric field, thereby producing collisional reactions between propagating pulse-like bands of these species, which we image optically. For certain pairs of anionic and cationic dyes, propagating bands pass through each other unperturbed; yet, for other pairs, we observe complexing and precipitation reactions, indicating strong attractive interactions. We generalize this band-collision gel electrophoresis (BCGE) approach to other reaction types, including acid-base, ligand exchange, and redox, as well as to colloidal species in passivated large-pore gels

Cycling Willingness: Investigating Distance as a Dependent Variable in Cycling Behavior Among College Students

We present a novel approach to understanding distance as a barrier to cycling and its use as a dependent variable in multinomial logistic regression. In doing so, this study explores distances in relation to spatially and relevant human factors such as gender and propensity to cycle among college students. College students (N = 949) participated in a health survey and stated possible predictors of cycling based on their cycle usage and preferences in the previous 30 days. While utilizing GIS in a bicycle-friendly network, we created geo-statistical GIS-groupings and performed multinomial logistic regression analysis. We examined college students to discover how their demographic and personal characteristics may mediate the deterrent properties of distance when considered as a dependent variable in cycling to a college campus. Age and propensity for cycling for transportation mediate the negative effect of distance on the likelihood of cycling. The findings also suggest that infrastructure improvements could lessen the impact of distance as a barrier to cycling and increase the likelihood of cycling for commuting

Crossover between entropic and interfacial elasticity and osmotic pressure in uniform disordered emulsions

We develop a simple predictive model of the osmotic pressure Π and linear shear elastic modulus G′p of uniform disordered emulsions that includes energetic contributions from entropy and interfacial deformation. This model yields a smooth crossover between an entropically dominated G′p ∼ kBT/a³ for droplet volume fractions ϕ below a jamming threshold for spheres, ϕc, and an interfacially dominated G′p ∼ σ/a for ϕ above ϕc, where a and σ are the undeformed radius and interfacial tension, respectively, of a droplet and T is the temperature. We show that this model reduces to the known ϕ-dependent jamming behavior G′p(ϕ) ∼ (σ/a)ϕ(ϕ − ϕc) as T → 0 for ϕ > ϕc of disordered uniform emulsions, and it also produces the known divergence for disordered hard spheres G′p(ϕ) ∼ (kBT/a³)ϕ/(ϕc − ϕ) for ϕ ϕc when σ → ∞. We compare predictions of this model to data for disordered uniform microscale emulsion droplets, corrected for electrostatic repulsions. The smooth crossover captures the observed trends in G′p and Π below ϕc better than existing analytic models of disordered emulsions, which do not make predictions below ϕc. Moreover, the model predicts that entropic contributions to the shear modulus can become more significant for nanoemulsions as compared to microscale emulsions.LaMnO

Exploring Patterns of Tax Increment Financing Use and Structural Explanations in Missouri’s Major Metropolitan Regions

This article examines tax increment financing (TIF) in Kansas City and St. Louis, two heavy users of the tool under the same statutory authority. Based on a complete database of TIF projects through 2013 (2012 for Kansas City) and numerous interviews with local government officials in both metropolitan areas, we explore the TIF use of these two cities, which have different structural aspects and have gone through sharp policy changes, to examine if central cities that use different strategies beget different outcomes in their suburban areas. We document distinctly different patterns of use in the two central cities. When St. Louis dramatically increased its TIF use under Mayor Francis Slay, the number of projects per year in the suburbs increased. Kansas City suburbs appeared to fill the gap in TIF use when the city sharply decreased its use of TIF under Mayor Mark Funkhouser. More research is needed to determine the factors that drive these mixed effects and if they hold true by context and in other metropolitan areas

3D Imaging of a Phase Object from a Single Sample Orientation Using an Optical Laser

Ankylography is a new 3D imaging technique, which, under certain circumstances, enables reconstruction of a 3D object from a single sample orientation. Here, we provide a matrix rank analysis to explain the principle of ankylography. We then present an ankylography experiment on a microscale phase object using an optical laser. Coherent diffraction patterns are acquired from the phase object using a planar CCD detector and are projected onto a spherical shell. The 3D structure of the object is directly reconstructed from the spherical diffraction pattern. This work may potentially open the door to a new method for 3D imaging of phase objects in the visible light region. Finally, the extension of ankylography to more complicated and larger objects is suggested.Comment: 22 pages 5 figure