Water at an electrochemical interface - a simulation study

The results of molecular dynamics simulations of the properties of water in an aqueous ionic solution close to an interface with a model metallic electrode are described. In the simulations the electrode behaves as an ideally polarizable hydrophilic metal, supporting image charge interactions with charged species, and it is maintained at a constant electrical potential with respect to the solution so that the model is a textbook representation of an electrochemical interface through which no current is passing. We show how water is strongly attracted to and ordered at the electrode surface. This ordering is different to the structure that might be imagined from continuum models of electrode interfaces. Further, this ordering significantly affects the probability of ions reaching the surface. We describe the concomitant motion and configurations of the water and ions as functions of the electrode potential, and we analyze the length scales over which ionic atmospheres fluctuate. The statistics of these fluctuations depend upon surface structure and ionic strength. The fluctuations are large, sufficiently so that the mean ionic atmosphere is a poor descriptor of the aqueous environment near a metal surface. The importance of this finding for a description of electrochemical reactions is examined by calculating, directly from the simulation, Marcus free energy profiles for transfer of charge between the electrode and a redox species in the solution and comparing the results with the predictions of continuum theories. Significant departures from the electrochemical textbook descriptions of the phenomenon are found and their physical origins are characterized from the atomistic perspective of the simulations.Comment: 29 pages, 15 figure

Cosmic background radiation at 408 Mc/s

Continuum cosmic radio emission can be completely described by three observable parameters, (1) the brightness distribution, (2) spectrum, and (3) polarization of the radiation. The purpose of the present investigation is to discuss the "background" component of the observed radio emission, its brightness distribution, absolute brightness temperature, and origins. For the purpose of this thesis, the background radiation is defined as the nearly isotropic component of the emission on which are superimposed strong discrete radio sources, radiation from the disk, or plane, of our own Galaxy, and contributions from within our own solar system

Expanding the CRISPR toolbox for use within Bacillus subtilis

DNA editing is a vital tool in the development of biological systems for both research and commercial applications. Novel enabling tools accelerate strain engineering for the study of cellular mechanisms or production of small molecules and proteins. CRISPR (Clustered Regularly Interspersed Short Palindromic Repeats) technologies, where small RNA molecules (gRNA) direct Cas (CRISPR-associated) proteins to DNA in a highly accurate, sequence-dependent manner have increased the rate at which DNA modifications can be made. We developed and expanded the CRISPR toolbox for recombination and deaminase-guided genome editing, protein engineering and transcriptional regulation within the industrial workhorse Bacillus subtilis. A co-transformational system, consisting of a single plasmid for nuclease and gRNA expression and a linear donor DNA (dDNA) was established for use with both Streptococcus pyogenes Cas9, the most commonly utilised CRISPR nuclease, as well as the potentially highly commercially relevant nuclease, MAD7, also known as Eubacterium rectale Cas12a. Editing efficiencies of ≥83% were observed for both nucleases. Using our CRISPR-Cas9 genome editing tool, a novel variant of the commercially relevant protein, subtilisin E, was engineered exhibiting an increase in both thermostability and proteolytic efficiency. Two systems for transcriptional down-regulation (CRISPRi) were demonstrated, including the first reported catalytically inactive variant of MAD7. Finally, Cas9 was further modified to incorporate fusions with DNA deaminases allowing the first reported example of CRISPR targeted deaminase base editing within B. subtilis

FIMCAR XIII: Cost Benefit Analysis

Although the number of road accident casualties in Europe is falling the problem still remains substantial. In 2011 there were still over 30,000 road accident fatalities [EC 2012]. Approximately half of these were car occupants and about 60 percent of these occurred in frontal impacts. The next stage to improve a car’s safety performance in frontal impacts is to improve its compatibility for car-to-car impacts and for collisions against objects and HGVs. Compatibility consists of improving both a car’s self and partner protection in a manner such that there is good interaction with the collision partner and the impact energy is absorbed in the car’s frontal structures in a controlled way which results in a reduction of injuries. Over the last ten years much research has been performed which has found that there are four main factors related to a car’s compatibility [Edwards 2003, Edwards 2007]. These are structural interaction potential, frontal force matching, compartment strength and the compartment deceleration pulse and related restraint system performance. The objective of the FIMCAR FP7 EC-project was to develop an assessment approach suitable for regulatory application to control a car’s frontal impact and compatibility crash performance and perform an associated cost benefit analysis for its implementation

Clinical Review : The suggested management pathway for urticaria in primary care

ACKNOWLEDGEMENTS There was no funding and all the work was done by the authors.Peer reviewedPublisher PD

Anthropometric correlates of human anger

This is the post-print version of the final paper published in Evolution and Human Behavior. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.The recalibrational theory of human anger predicts positive correlations between aggressive formidability and anger levels in males, and between physical attractiveness and anger levels in females. We tested these predictions by using a three-dimensional body scanner to collect anthropometric data about male aggressive formidability (measures of upper body muscularity and leg–body ratio) and female bodily attractiveness (waist–hip ratio, body mass index, overall body shape femininity, and several other measures). Predictions were partially supported: in males, two of three anger measures correlated significantly positively with several muscularity measures; in females, self-perceived attractiveness correlated significantly positively with two anger measures. However, most of these significant results were observed only after excluding from the sample 27 participants who were older than undergraduate age, leaving a subsample of 40 males and 51 females. Evidence for relationships between anthropometric attractiveness indicators and anger measures was weak, but there was some evidence for relationships between anthropometric attractiveness indicators and self-perceived attractiveness measures. While our results support the recalibrational theory's prediction that anger usage and formidability are positively correlated in males and suggest that this formidability can be assessed via anthropometric measures alone, they also suggest that this prediction may not apply to populations older than undergraduate age. Further, our results suggest that while female anger levels relate positively to self-perceived attractiveness, they are unrelated to most anthropometric measures of bodily attractiveness

Multi-Dimensional, Compressible Viscous Flow on a Moving Voronoi Mesh

Numerous formulations of finite volume schemes for the Euler and Navier-Stokes equations exist, but in the majority of cases they have been developed for structured and stationary meshes. In many applications, more flexible mesh geometries that can dynamically adjust to the problem at hand and move with the flow in a (quasi) Lagrangian fashion would, however, be highly desirable, as this can allow a significant reduction of advection errors and an accurate realization of curved and moving boundary conditions. Here we describe a novel formulation of viscous continuum hydrodynamics that solves the equations of motion on a Voronoi mesh created by a set of mesh-generating points. The points can move in an arbitrary manner, but the most natural motion is that given by the fluid velocity itself, such that the mesh dynamically adjusts to the flow. Owing to the mathematical properties of the Voronoi tessellation, pathological mesh-twisting effects are avoided. Our implementation considers the full Navier-Stokes equations and has been realized in the AREPO code both in 2D and 3D. We propose a new approach to compute accurate viscous fluxes for a dynamic Voronoi mesh, and use this to formulate a finite volume solver of the Navier-Stokes equations. Through a number of test problems, including circular Couette flow and flow past a cylindrical obstacle, we show that our new scheme combines good accuracy with geometric flexibility, and hence promises to be competitive with other highly refined Eulerian methods. This will in particular allow astrophysical applications of the AREPO code where physical viscosity is important, such as in the hot plasma in galaxy clusters, or for viscous accretion disk models.Comment: 26 pages, 21 figures. Submitted to MNRA

Management of type II superior labrum anterior posterior lesions: a review of the literature

Superior labrum anterior and posterior lesions were first described in 1985 by Andrews et al. and later classified into four types by Synder et al. The most prevalent is type II which is fraying of the superior glenoid labrum with detachment of the biceps anchor. Superior labrum anterior posterior (SLAP) lesions can also be associated with other shoulder pathology. Both MRI and MRA can be utilized in making the diagnosis with the coronal images being the most sensitive. The mechanism of injury can be either repetitive stress or acute trauma with the superior labrum most vulnerable to injury during the late cocking phase of throwing. A combination of the modified dynamic labral shear and O'Brien test can be used clinically in making the diagnosis of SLAP lesion. However, the most sensitive and specific test used to diagnosis specifically a type II SLAP lesion is the Biceps Load Test II. The management of type II SLAP lesions is controversial and dependent on patient characteristics. In the young high demanding overhead athlete, repair of the type II lesion is recommended to prevent glenohumeral instability. In middle-aged patients (age 25–45), repair of the type II SLAP lesion with concomitant treatment of other shoulder pathology resulted in better functional outcomes and patient satisfaction. Furthermore, patients who had a distinct traumatic event resulting in the type II SLAP tear did better functionally than patients who did not have the traumatic event when the lesion was repaired. In the older patient population (age over 45 years), minimum intervention (debridement, biceps tenodesis/tenotomy) to the type II SLAP lesion results in excellent patient satisfaction and outcomes