Differential sensitivity of aerobic gram-positive and gram-negative microorganisms to 2,4,6-trinitrotoluene (TNT) leads to dissimilar growth and TNT transformation: Results of soil and pure culture studies

The effects of 2,4,6-trinitrotoluene (TNT) on indigenous soil populations and pure bacterial cultures were examined. The number of colony-forming units (CFU) appearing when TNT-contaminated soil was spread on 0.3% molasses plates decreased by 50% when the agar was amended with 67 {mu}g TNT mL{sup -1}, whereas a 99% reduction was observed when uncontaminated soil was plated. Furthermore, TNT-contaminated soil harbored a greater number of organisms able to grow on plates amended with greater than 10 {mu}g TNT mL{sup -1}. The percentage of gram-positive isolates was markedly less in TNT-contaminated soil (7%; 2 of 30) than in uncontaminated soil (61%; 20 of 33). Pseudomonas aeruginosa, Pseudomonas corrugate, Pseudomonasfluorescens and Alcaligenes xylosoxidans made up the majority of the gram-negative isolates from TNT-contaminated soil. Gram-positive isolates from both soils demonstrated marked growth inhibition when greater than 8-16 {mu}g TNT mL{sup -1} was present in the culture media. Most pure cultures of known aerobic gram-negative organisms readily degraded TNT and evidenced net consumption of reduced metabolites. However, pure cultures of aerobic gram-positive bacteria were sensitive to relatively low concentrations of TNT as indicated by the 50% reduction in growth and TNT transformation which was observed at approximately 10 {mu}g TNT mL{sup -1}. Most non-sporeforming gram-positive organisms incubated in molasses media amended with 80 {mu}g TNT mL{sup -1} or greater became unculturable, whereas all strains tested remained culturable when incubated in mineral media amended with 98 {mu}g TNT mL{sup -1}, indicating that TNT sensitivity is likely linked to cell growth. These results indicate that gram-negative organisms are most likely responsible for any TNT transformation in contaminated soil, due to their relative insensitivity to high TNT concentrations and their ability to transform TNT

Improved Nearside-Farside Decomposition of Elastic Scattering Amplitudes

A simple technique is described, that provides improved nearside-farside (NF) decompositions of elastic scattering amplitudes. The technique, involving the resummation of a Legendre partial wave series, reduces the importance of unphysical contributions to NF subamplitudes, which can arise in more conventional NF decompositions. Applications are made to a strong absorption model and to a $^{16}$O + $^{12}$C optical potential at $E_{\text{lab}} = 132$ MeV.Comment: 5 pages, 2 figure

Refractive elastic scattering of carbon and oxygen nuclei: The mean field analysis and Airy structures

The experimental data on the $^{16}$O$+^{12}$C and $^{18}$O$+^{12}$C elastic scatterings and their optical model analysis are presented. Detailed and complete elastic angular distributions have been measured at the Strasbourg Vivitron accelerator at several energies covering the energy range between 5 and 10 MeV per nucleon. The elastic scattering angular distributions show the usual diffraction pattern and also, at larger angles, refractive effects in the form of nuclear rainbow and associated Airy structures. The optical model analysis unambiguously shows the evolution of the refractive scattering pattern. The observed structure, namely the Airy minima, can be consistently described by a nucleus-nucleus potential with a deep real part and a weakly absorptive imaginary part. The difference in absorption in the two systems is explained by an increased imaginary (mostly surface) part of the potential in the $^{18}$O$+^{12}$C system. The relation between the obtained potentials and those reported for the symmetrical $^{16}$O$+^{16}$O and $^{12}$C$+^{12}$C systems is drawn.Comment: 10 pages, 9 figures, Phys. rev. C in pres

Anomalous NMR Spin-Lattice Relaxation in SrB_{6} and Ca_{1-x}La_{x}B_{6}

We report the results of {11}B nuclear magnetic resonance (NMR) measurements of SrB_{6} and Ca_{0.995}La_{0.05}B_{6} below room temperature. Although the electrical resistivities of these two materials differ substantially, their {11}B-NMR responses exhibit some strikingly common features. Both materials exhibit ferromagnetic order, but their {11}B-NMR spectra reveal very small hyperfine fields at the Boron sites. The spin lattice relaxation T_{1}^{-1} varies considerably with external field but changes with temperature only below a few K. We discuss these unusual results by considering various different scenarios for the electronic structure of these materials.Comment: Accepted for publication in Phys. Rev. B Rapid communication, 4 pages, 3 figures. This manuscript replaces an earlier version and includes some minor changes in the text and in Fig.

Shear-banding in a lyotropic lamellar phase, Part 1: Time-averaged velocity profiles

Using velocity profile measurements based on dynamic light scattering and coupled to structural and rheological measurements in a Couette cell, we present evidences for a shear-banding scenario in the shear flow of the onion texture of a lyotropic lamellar phase. Time-averaged measurements clearly show the presence of structural shear-banding in the vicinity of a shear-induced transition, associated to the nucleation and growth of a highly sheared band in the flow. Our experiments also reveal the presence of slip at the walls of the Couette cell. Using a simple mechanical approach, we demonstrate that our data confirms the classical assumption of the shear-banding picture, in which the interface between bands lies at a given stress $\sigma^\star$. We also outline the presence of large temporal fluctuations of the flow field, which are the subject of the second part of this paper [Salmon {\it et al.}, submitted to Phys. Rev. E]

First-order cosmological phase transitions in the radiation dominated era

We consider first-order phase transitions of the Universe in the radiation-dominated era. We argue that in general the velocity of interfaces is non-relativistic due to the interaction with the plasma and the release of latent heat. We study the general evolution of such slow phase transitions, which comprise essentially a short reheating stage and a longer phase equilibrium stage. We perform a completely analytical description of both stages. Some rough approximations are needed for the first stage, due to the non-trivial relations between the quantities that determine the variation of temperature with time. The second stage, instead, is considerably simplified by the fact that it develops at a constant temperature, close to the critical one. Indeed, in this case the equations can be solved exactly, including back-reaction on the expansion of the Universe. This treatment also applies to phase transitions mediated by impurities. We also investigate the relations between the different parameters that govern the characteristics of the phase transition and its cosmological consequences, and discuss the dependence of these parameters with the particle content of the theory.Comment: 38 pages, 3 figures; v2: Minor changes, references added; v3: several typos correcte

Surface preparation of powder metallurgical tool steels by means of wire electrical discharge machining

The surface of two types of powder metallurgical (PM) tool steels (i.e., with and without nitrogen) was prepared using wire electrical discharge machining (WEDM). From each grade of tool steel, seven surfaces corresponding to one to seven passes of WEDM were prepared. The WEDM process was carried out using a brass wire as electrode and deionized water as dielectric. After eachWEDM pass the surface of the tool steels was thoroughly examined. Surface residual stresses were measured by the X-ray diffraction (XRD) technique. The measured stresses were found to be of tensile nature. The surface roughness of the WEDM specimens was measured using interference microscopy. The surface roughness as well as the residual stress measurements indicated an insignificant improvement of these parameters after four passes of WEDM. In addition, the formed recast layer was characterized by means of scanning electron microscopy (SEM), XRD, and X-ray photoelectron spectroscopy (XPS). The characterization investigation clearly shows diffusion of copper and zinc from the wire electrode into the work material, even after the final WEDM step. Finally, the importance of eliminating excessive WEDM steps is thoroughly discussed

The evolutionary history of wild, domesticated, and feral brassica oleracea (Brassicaceae)

Understanding the evolutionary history of crops, including identifying wild relatives, helps to provide insight for conservation and crop breeding efforts. Cultivated Brassica oleracea has intrigued researchers for centuries due to its wide diversity in forms, which include cabbage, broccoli, cauliflower, kale, kohlrabi, and Brussels sprouts. Yet, the evolutionary history of this species remains understudied. With such different vegetables produced from a single species, B. oleracea is a model organism for understanding the power of artificial selection. Persistent challenges in the study of B. oleracea include conflicting hypotheses regarding domestication and the identity of the closest living wild relative. Using newly generated RNA-seq data for a diversity panel of 224 accessions, which represents 14 different B. oleracea crop types and nine potential wild progenitor species, we integrate phylogenetic and population genetic techniques with ecological niche modeling, archaeological, and literary evidence to examine relationships among cultivars and wild relatives to clarify the origin of this horticulturally important species. Our analyses point to the Aegean endemic B. cretica as the closest living relative of cultivated B. oleracea, supporting an origin of cultivation in the Eastern Mediterranean region. Additionally, we identify several feral lineages, suggesting that cultivated plants of this species can revert to a wild-like state with relative ease. By expanding our understanding of the evolutionary history in B. oleracea, these results contribute to a growing body of knowledge on crop domestication that will facilitate continued breeding efforts including adaptation to changing environmental conditions

The Business Model: Recent Developments and Future Research

This article provides a broad and multifaceted review of the received literature on business models in which the authors examine the business model concept through multiple subject-matter lenses. The review reveals that scholars do not agree on what a business model is and that the literature is developing largely in silos, according to the phenomena of interest of the respective researchers. However, the authors also found emerging common themes among scholars of business models. Specifically, (1) the business model is emerging as a new unit of analysis; (2) business models emphasize a system-level, holistic approach to explaining how firms “do business”; (3) firm activities play an important role in the various conceptualizations of business models that have been proposed; and (4) business models seek to explain how value is created, not just how it is captured. These emerging themes could serve as catalysts for a more unified study of business models

Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice

Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales