Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering.

The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the peptides are separated. Cuts through the RIXS maps furthermore allow monitoring selective excitations of the amino and peptide functional units, leading to a modification of the currently established assignment of spectral contributions. The results thus paint a new-and-improved picture of the peptide bond, enhance the understanding of larger molecules with peptide bonds, and simplify the investigation of such molecules in aqueous environment

Resistance of legionella pneumophila and helicobacter pylori to chlorination in drinking water biofilms

The disintegration of concrete structures made of ordinary Portland cement (OPC) is a worrying topic of increasing significance. The development of new binders with longer durability is therefore needed. Alkali-activated binders have emerged as an alternative to OPC binders, which seems to have superior durability and environmental impact. This paper reviews current knowledge about alkali-activated binders. The subjects of Part 1 in this paper are historical background, terminology and hydration products. The proper terminology to designate these new binders will be discussed. The influence of the prime materials and the type of alkaline activator on the reaction mechanisms and on the nature of the reaction products will be described

Community interactions promote Legionella pneumophila survival in drinking water biofilms

Legionella pneumophila is a waterborne pathogen that can cause Pontiac Fever or Legionnaires’ disease, a type of pneumonia that can be fatal. Although L. pneumophila is not able to replicate in low nutrient environments, such as drinking water, it is known that heterotrophic biofilms have a crucial role in the survival of this pathogen in drinking water distribution systems. The aim of this work is to study the community interactions that influence the survival of L. pneumophila in biofilms. For that, mono and dual-species biofilms of L. pneumophila and the predominant biofilm isolates Variovorax paradoxus, Mycobacterium chelonae, Acidovorax spp., Sphingomonas spp., were formed on PVC surfaces and sessile cells quantified for total cells, viable and cultivable L. pneumophila and cultivable non-Legionellae. Results demonstrated that Acidovorax spp. and Sphingomonas spp. appear to have an antagonistic effect on L. pneumophila cultivability but not in the viability, leading to the formation of viable but noncultivable (VBNC) cells, while M. chelonae increased the cultivability of this pathogen. M. chelonae is one of the microorganisms commonly found in drinking water and this work demonstrates that this strain is able to promote L. pneumophila survival in these systems. It is also demonstrated that other species might stimulate this pathogen to enter a VBNC state and consequently be underestimated in the drinking water quality control, as drinking water safety assessment still relies on standard culture techniques. It is essential for future work to study other biofilm community members to understand their ecological interactions with L. pneumophila

Influence of physico-chemical parameters on the survival of Helicobacter pylori in drinking water biofilms

The route of transmission for Helicobacter pylori is not well-known, but one of the suggested possibilities is via drinking water and associated biofilms. As such, the aim of this work is to study the influence of several physico-chemical parameters, including temperature, shear-stress and carbon concentration, on the prevalence and survival of H. pylori in drinking water biofilms. The biofilm studies were carried out using a two-stage chemostat system. The outflow culture of the first vessel fed three secondary chemostats in parallel and under different conditions of shear stress and carbon concentration. After 10 days the chemostats reached steady conditions, and the second stage chemostats were spiked with an inoculum of H. pylori NCTC 11637 (of approximately 106 cells ml-1) and PVC coupons were then immersed to allow biofilm formation. The coupons were removed at different times (up to 32 days) and biofilms detached with sterile glass beads. Planktonic and sessile cells were quantified by standard cultivation techniques (R2A and HPSPA) and SYTO9 staining. Remarkably, H. pylori lost cultivability under all conditions in less than 1 h which compares with 24-75 h that the pathogen usually takes to lose cultivability in pure culture at these temperatures. This suggests that H. pylori is negatively affected by the presence of heterotrophic microbial consortium; alternatively, overgrowth of other species might hinder colony development of H. pylori. Current studies are tracking the uncultivable H. pylori in the biofilms using peptide nucleic acid probes in a high performance fluorescence in situ hybridisation assay

Estimations of electron-positron pair production at high-intensity laser interaction with high-Z targets

Electron-positron pairs' generation occuring in the interaction of $10^{18}$-$10^{20}$~W/cm$^2$ laser radiation with high-Z targets are examined. Computational results are presented for the pair production and the positron yield from the target with allowance for the contribution of pair production processes due to electrons and bremsstrahlung photons. Monte-Carlo simulations using the PRIZMA code confirm the estimates obtained. The possible positron yield from high-Z targets irradiated by picosecond lasers of power $10^2$-$10^3$~TW is estimated to be $10^9$-$10^{11}$

A New Technique for Finding Needles in Haystacks: A Geometric Approach to Distinguishing Between a New Source and Random Fluctuations

We propose a new test statistic based on a score process for determining the statistical significance of a putative signal that may be a small perturbation to a noisy experimental background. We derive the reference distribution for this score test statistic; it has an elegant geometrical interpretation as well as broad applicability. We illustrate the technique in the context of a model problem from high-energy particle physics. Monte Carlo experimental results confirm that the score test results in a significantly improved rate of signal detection.Comment: 5 pages, 4 figure

A Framework for Supervision for Mindfulness-Based Teachers:a Space for Embodied Mutual Inquiry

Over recent decades, there has been an exponential growth in mindfulness-based interventions (MBIs). To disseminate MBIs with fidelity, care needs to be taken with the training and supervision of MBI teachers. A wealth of literature exists describing the process and practice of supervision in a range of clinical approaches, but, as of yet, little consideration has been given to how this can best be applied to the supervision of MBI teachers. This paper articulates a framework for supervision of MBI teachers. It was informed by the following: the experience of eight experienced mindfulness-based supervisors, the literature and understandings from MBIs, and by the authors’ experience of training and supervision. It sets out the nature and distinctive features of mindfulness-based supervision (MBS), representing this complex, multilayered process through a series of circles that denote its essence, form, content and process. This paper aims to be a basis for further dialogue on MBS, providing a foundation to increase the availability of competent supervision so that MBIs can expand without compromising integrity and efficacy

Observation of Superfluid Flow in a Bose-Einstein Condensed Gas

We have studied the hydrodynamic flow in a Bose-Einstein condensate stirred by a macroscopic object, a blue detuned laser beam, using nondestructive {\em in situ} phase contrast imaging. A critical velocity for the onset of a pressure gradient has been observed, and shown to be density dependent. The technique has been compared to a calorimetric method used previously to measure the heating induced by the motion of the laser beam.Comment: 4 pages, 5 figure