Equilibrium Dynamics of Microemulsion and Sponge Phases

The dynamic structure factor $G({\bf k},\omega)$ is studied in a time-dependent Ginzburg-Landau model for microemulsion and sponge phases in thermal equilibrium by field-theoretic perturbation methods. In bulk contrast, we find that for sufficiently small viscosity $\eta$, the structure factor develops a peak at non-zero frequency $\omega$, for fixed wavenumber $k$ with $k_0 < k {< \atop \sim} q$. Here, $2\pi/q$ is the typical domain size of oil- and water-regions in a microemulsion, and $k_0 \sim \eta q^2$. This implies that the intermediate scattering function, $G({\bf k}, t)$, {\it oscillates} in time. We give a simple explanation, based on the Navier-Stokes equation, for these temporal oscillations by considering the flow through a tube of radius $R \simeq \pi/q$, with a radius-dependent tension.Comment: 24 pages, LaTex, 11 Figures on request; J. Phys. II France 4 (1994) to be publishe

Magnetoelastic effects and random magnetic anisotropy in highly strained ultrathin Ni nanowires epitaxied in a SrTiO3 matrix

International audienceWe analyze the magnetic anisotropy of Ni nanowires with diameters smaller than 5 nm. The nanowires are vertically epitaxied in a SrTiO 3 (001) matrix which generates huge tensile strains up to 3.6% along the nanowire axis. This leads to an unusual anisotropy, characterized by an easy magnetization plane perpendicular to the nanowire axis. Hysteresis cycles M(H) unveil an overall in-plane isotropy, while an opening of the M(H) cycles and thermal activation measurements indicate the presence of local energy barriers inside the nanowires. Surprisingly, the coercive field H c (T) decays exponentially with increasing temperature, for both the easy plane and the hard axis. Based on these findings, we provide an analysis of magnetoelastic effects in the nanowires. By considering global averaging over the anisotropy distribution and local averaging according to the Random Magnetic Anisotropy model, we find that the global anisotropy, with its hard axis and isotropic easy plane, is related to the mean strain, while coercivity arises from local strain variations. We evidence that a thermally activated anisotropy softening occurs in the nanowires, in addition to Sharrock's law of thermal reduction of coercivity. Possible mechanisms responsible for this thermal softening of anisotropy are proposed and discussed. Our study eventually allows to identify two major competing effects at play in the present system: an increasing magnetic anisotropy with increasing strain and a reduction of the anisotropy with increasing local strain fluctuations

Improving the sensitivity of future GW observatories in the 1-10 Hz band: Newtonian and seismic noise

The next generation gravitational wave interferometric detectors will likely be underground detectors to extend the GW detection frequency band to frequencies below the Newtonian noise limit. Newtonian noise originates from the continuous motion of the Earth’s crust driven by human activity, tidal stresses and seismic motion, and from mass density fluctuations in the atmosphere. It is calculated that on Earth’s surface, on a typical day, it will exceed the expected GW signals at frequencies below 10 Hz. The noise will decrease underground by an unknown amount. It is important to investigate and to quantify this expected reduction and its effect on the sensitivity of future detectors, to plan for further improvement strategies. We report about some of these aspects. Analytical models can be used in the simplest scenarios to get a better qualitative and semi-quantitative understanding. As more complete modeling can be done numerically, we will discuss also some results obtained with a finite-element-based modeling tool. The method is verified by comparing its results with the results of analytic calculations for surface detectors. A key point about noise models is their initial parameters and conditions, which require detailed information about seismic motion in a real scenario. We will describe an effort to characterize the seismic activity at the Homestake mine which is currently in progress. This activity is specifically aimed to provide informations and to explore the site as a possible candidate for an underground observatory. Although the only compelling reason to put the interferometer underground is to reduce the Newtonian noise, we expect that the more stable underground environment will have a more general positive impact on the sensitivity.We will end this report with some considerations about seismic and suspension noise

Atomic-Scale Study of Metal–Oxide Interfaces and Magnetoelastic Coupling in Self-Assembled Epitaxial Vertically Aligned Magnetic Nanocomposites

Vertically aligned nanocomposites (VANs) of metal/oxide type have recently emerged as a novel class of heterostructures with great scientific and technological potential in the fields of nanomagnetism, multiferroism, and catalysis. One of the salient features of these hybrid materials is their huge vertical metal/oxide interface, which plays a key role in determining the final magnetic and/or transport properties of the composite structure. However, in contrast to their well‐studied planar counterparts, detailed information on the structural features of vertical interfaces encountered in VANs is scarce. In this work, high resolution scanning transmission electron microscopy (STEM) and electron energy‐loss spectroscopy (EELS) are used to provide an element selective atomic‐scale analysis of the interface in a composite consisting of ultrathin, self‐assembled Ni nanowires, vertically epitaxied in a SrTiO3/SrTiO3(001) matrix. Spectroscopic EELS measurements evidence rather sharp interfaces (6–7 Å) with the creation of metallic NiTi bonds and the absence of nickel oxide formation is confirmed by X‐ray absorption spectroscopy measurements. The presence of these well‐defined phase boundaries, combined with a large lattice mismatch between the oxide and metallic species, gives rise to pronounced magnetoelastic effects. Self‐assembled columnar Ni:SrTiO3 composites thus appear as ideal model systems to explore vertical strain engineering in metal/oxide nanostructures

Identification of a Novel Pseudo-Natural Product Type IV IDO1 Inhibitor Chemotype

Natural product (NP)-inspired design principles provide invaluable guidance for bioactive compound discovery. Pseudo-natural products (PNPs) are de novo combinations of NP fragments to target biologically relevant chemical space not covered by NPs. We describe the design and synthesis of apoxidoles, a novel pseudo-NP class, whereby indole- and tetrahydropyridine fragments are linked in monopodal connectivity not found in nature. Apoxidoles are efficiently accessible by an enantioselective [4+2] annulation reaction. Biological evaluation revealed that apoxidoles define a new potent type IV inhibitor chemotype of indoleamine 2,3-dioxygenase 1 (IDO1), a heme-containing enzyme considered a target for the treatment of neurodegeneration, autoimmunity and cancer. Apoxidoles target apo-IDO1, prevent heme binding and induce unique amino acid positioning as revealed by crystal structure analysis. Novel type IV apo-IDO1 inhibitors are in high demand, and apoxidoles may provide new opportunities for chemical biology and medicinal chemistry research

The communication of a secondary care diagnosis of autoimmune hepatitis to primary care practitioners: a population-based study

Background Autoimmune Hepatitis is a chronic liver disease which affects young people and can result in liver failure leading to death or transplantation yet there is a lack of information on the incidence and prevalence of this disease and its natural history in the UK. A means of obtaining this information is via the use of clinical databases formed of electronic primary care records. How reliably the diagnosis is coded in such records is however unknown. The aim of this study therefore was to assess the proportion of consultant hepatologist diagnoses of Autoimmune Hepatitis which were accurately recorded in General Practice computerised records. Methods Our study population were patients with Autoimmune Hepatitis diagnosed by consultant hepatologists in the Queens Medical Centre, Nottingham University Hospitals (UK) between 2004 and 2009. We wrote to the general practitioners of these patients to obtain the percentage of patients who had a valid READ code specific for Autoimmune Hepatitis. Results We examined the electronic records of 51 patients who had biopsy evidence and a possible diagnosis of Autoimmune Hepatitis. Forty two of these patients had a confirmed clinical diagnosis of Autoimmune Hepatitis by a consultant hepatologist: we contacted the General Practitioners of these patients obtaining a response rate of 90.5% (39/42 GPs). 37/39 of these GPs responded with coding information and 89% of these patients (33/37) used Read code J638.00 (Autoimmune Hepatitis) to record a diagnosis. Conclusions The diagnosis of Autoimmune Hepatitis made by a Consultant Hepatologist is accurately communicated to and electronically recorded by primary care in the UK. As a large proportion of cases of Autoimmune Hepatitis are recorded in primary care, this minimises the risk of introducing selection bias and therefore selecting cases using these data will be a valid method of conducting population based studies on Autoimmune Hepatitis