Weakly Forced Thunderstorms in the Southeast US Are Stronger Near Urban Areas

Abstract While cities are well documented to enhance precipitation through the urban rainfall effect (URE), the distinguishing characteristics of urban‐influenced storms that help establish the URE are poorly understood. The purpose of this study is to examine the morphological traits (i.e., size, duration, intensity, etc.) and near‐storm environmental conditions of weakly forced thunderstorms (WFTs) occurring near urban areas in the Southeast US relative to storms forming in surrounding rural areas. Urban WFTs are found to have higher reflectivities, are more likely to contain hail, and produce more lightning than nearby non‐urban storms, but their sizes and shapes are statistically indistinguishable. When disaggregated across individual urban areas, the increase in maximum composite reflectivity among urban storms is the most pervasive morphological difference, with 24 of the 31 cities displaying elevated reflectivities. Urban WFTs also benefit from near‐storm environments with greater instability and higher precipitation efficiency, which may further contribute to the URE

A regular net of reciprocal synapses in the visual system of the fly, Musca domestica

In the first visual ganglion of the fly (Musca domestica) there are many similar visual channels (ldquocartridgesrdquo), connected to each other by various systems of fibers, the most regular of which consists of the collateral branches of the L4 neuron, which is contained in each cartridge. The three collaterals of L4 run to three different cartridges, one of which is the parent cartridge of the neuron, the other two being neighbours of that cartridge in two directions of an hexagonal array (Figs. 1a, 3). Within each cartridge there are thus the endings of three collaterals (from three different L4 neurons). These make close physical contact, and serial sectioning shows that each collateral is presynaptic to the other two (Fig. 2). It follows that there are reciprocal synapses between any pair of these collaterals. The network of relationships thus set up is the simplest scheme of coupling in a hexagonal array (Fig. 1a, b, c)

Albumin-based nanoparticles as magnetic resonance contrast agents : I. Concept, first syntheses and characterisation

Abstract To develop a platform for molecular magnetic resonance imaging, we prepared gadolinium-bearing albumin-polylactic acid nanoparticles in the size range 20–40 nm diameter. Iterative cycles of design and testing upscaled the synthesis procedures to gram amounts for physicochemical characterisation and for pharmacokinetic testing. Morphological analyses showed that the nanoparticles were spheroidal with rough surfaces. Particle sizes were measured by direct transmission electron microscopical measurements from negatively contrasted preparations, and by use of photon correlation spectroscopy; the two methods each documented nanoparticle sizes less than 100 nm and generally 10–40 nm diameter, though with significant intrabatch and interbatch variability. The particles’ charge sufficed to hold them in suspension. HSA retained its tertiary structure in the particles. The nanoparticles were stable against turbulent flow conditions and against heat, though not against detergents. MRI imaging of liquid columns was possible at nanoparticle concentrations below 10 mg/ml. The particles were non-cytotoxic, non-thrombogenic and non-immunogenic in a range of assay systems developed for toxicity testing of nanoparticles. They were micellar prior to lyophilisation, but loosely structured aggregated masses after lyophilisation and subsequent resuspension. These nanoparticles provide a platform for further development, based on non-toxic materials of low immunogenicity already in clinical use,not expensive, and synthesized using methods which can be upscaled for industrial production.</p