Performance of the Colorado wind-profiling network, part 1.5A

The Wave Propagation Laboratory (WPL) has operated a network of radar wind Profilers in Colorado for about 1 year. The network consists of four VHF (50-MHz) radars and a UHF (915-MHz) radar. The Platteville VHF radar was developed by the Aeronomy Laboratory (AL) and has been operated jointly by WPL and AL for several years. The other radars were installed between February and May 1983. Experiences with these radars and some general aspects of tropospheric wind measurements with Doppler radar are discussed

Force steps during viral DNA packaging ?

Biophysicists and structural biologists increasingly acknowledge the role played by the mechanical properties of macromolecules as a critical element in many biological processes. This change has been brought about, in part, by the advent of single molecule biophysics techniques that have made it possible to exert piconewton forces on key macromolecules and observe their deformations at nanometer length scales, as well as to observe the mechanical action of macromolecules such as molecular motors. This has opened up immense possibilities for a new generation of mechanical investigations that will respond to such measurements in an attempt to develop a coherent theory for the mechanical behavior of macromolecules under conditions where thermal and chemical effects are on an equal footing with deterministic forces. This paper presents an application of the principles of mechanics to the problem of DNA packaging, one of the key events in the life cycle of bacterial viruses with special reference to the nature of the internal forces that are built up during the DNA packaging process.Comment: 18 pages, 7 figures, To appear in the Journal of Mechanics and Physics of Solid

Viscous instabilities in flowing foams: A Cellular Potts Model approach

The Cellular Potts Model (CPM) succesfully simulates drainage and shear in foams. Here we use the CPM to investigate instabilities due to the flow of a single large bubble in a dry, monodisperse two-dimensional flowing foam. As in experiments in a Hele-Shaw cell, above a threshold velocity the large bubble moves faster than the mean flow. Our simulations reproduce analytical and experimental predictions for the velocity threshold and the relative velocity of the large bubble, demonstrating the utility of the CPM in foam rheology studies.Comment: 10 pages, 3 figures. Replaced with revised version accepted for publication in JSTA

DNA content of a functioning chicken kinetochore

© The Author(s) 2014. In order to understand the three-dimensional structure of the functional kinetochore in vertebrates, we require a complete list and stoichiometry for the protein components of the kinetochore, which can be provided by genetic and proteomic experiments. We also need to know how the chromatin-containing CENP-A, which makes up the structural foundation for the kinetochore, is folded, and how much of that DNA is involved in assembling the kinetochore. In this MS, we demonstrate that functioning metaphase kinetochores in chicken DT40 cells contain roughly 50 kb of DNA, an amount that corresponds extremely closely to the length of chromosomal DNA associated with CENP-A in ChIP-seq experiments. Thus, during kinetochore assembly, CENP-A chromatin is compacted into the inner kinetochore plate without including significant amounts of flanking pericentromeric heterochromatin. © 2014 The Author(s).Wellcome Trust [grant number 073915]; Wellcome Trust Centre for Cell Biology (core grant numbers 077707 and 092076); Darwin Trust of Edinburg

Regional variation in British English voice Quality

This study considers regional variation of voice quality in two varieties of British English - Southern Standard British English and West Yorkshire English. A comparison of voice quality profiles for three closely related but not identical northern varieties within West Yorkshire is also considered. Our findings do not contradict the small subset of previous research which explored regional and/or social variation in voice quality in British English insofar as regionality may play a small role in a speaker's voice quality profile. However, factors such as social standing and identity could perhaps be even more relevant. Even when considering homogeneous groups of speakers, it is not the case that there is a cohesive voice quality profile that can be attached to every speaker within the group. The reason for this, we argue, is the speaker-specificity inherent in voice quality

Effect of Casting Conditions on Some Mechanical Properties of Cobalt-Base Alloys

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67983/2/10.1177_00220345610400012601.pd

Breaking the limit: Super-Eddington accretion onto black holes and neutron stars

With the recent discoveries of massive and highly luminous quasars at high redshifts (z∼7; e.g. Mortlock et al. 2011), the question of how black holes (BHs) grow in the early Universe has been cast in a new light. In order to grow BHs with M_(BH) > 10^9 M⊙ by less than a billion years after the Big Bang, mass accretion onto the low-mass seed BHs needs to have been very rapid (Volonteri & Rees, 2005). Indeed, for any stellar remnant seed, the rate required would need to exceed the Eddington limit. This is the point at which the outward force produced by radiation pressure is equal to the gravitational attraction experienced by the in-falling matter. In principle, this implies that there is a maximum luminosity an object of mass M can emit; assuming spherical accretion and that the opacity is dominated by Thompson scattering, this Eddington luminosity is L_E = 1.38×10^(38)(M/M⊙) erg s^(−1). In reality, it is known that this limit can be violated, due to non-spherical geometry or various kinds of instabilities. Nevertheless, the Eddington limit remains an important reference point, and many of the details of how accretion proceeds above this limit remain unclear. Understanding how this so-called super-Eddington accretion occurs is of clear cosmological importance, since it potentially governs the growth of the first supermassive black holes (SMBHs) and the impact this growth would have had on their host galaxies (‘feedback') and the epoch of reionization, as well as improving our understanding of accretion physics more generally