Hadronic density of states from string theory

We present an exact calculation of the finite temperature partition function for the hadronic states corresponding to a Penrose-Güven limit of the Maldacena-Nù?ez embedding of the N=1 super Yang-Mills (SYM) into string theory. It is established that the theory exhibits a Hagedorn density of states. We propose a semiclassical string approximation to the finite temperature partition function for confining gauge theories admitting a supergravity dual, by performing an expansion around classical solutions characterized by temporal windings. This semiclassical approximation reveals a hadronic energy density of states of a Hagedorn type, with the coefficient determined by the gauge theory string tension as expected for confining theories. We argue that our proposal captures primarily information about states of pure N=1 SYM theory, given that this semiclassical approximation does not entail a projection onto states of large U(1) charge.     

Towards measuring variations of Casimir energy by a superconducting cavity

We consider a Casimir cavity, one plate of which is a thin superconducting film. We show that when the cavity is cooled below the critical temperature for the onset of superconductivity, the sharp variation (in the far infrared) of the reflection coefficient of the film engenders a variation in the value of the Casimir energy. Even though the relative variation in the Casimir energy is very small, its magnitude can be comparable to the condensation energy of the superconducting film, and this gives rise to a number of testable effects, including a significant increase in the value of the critical magnetic field, required to destroy the superconductivity of the film. The theoretical ground is therefore prepared for the first experiment ever aimed at measuring variations of the Casimir energy itself.     

Studies in organic mass spectrometry. Part 25. Benzyl ion formation in chemical ionisation (methane or isobutane) of some ortho-alkylhetero-substituted diphenylcarbinols

The behaviour of some ortho-alkylhetero-substituted diphenylcarbinols, including deuterium labelled derivatives, under chemical ionisation (methane or isobutane) conditions has been investigated. It has been determined that ortho-alkylhetero diphenylmethyl cations formed by water elimination from the protonated molecule undergo consecutive rearrangements which afford benzyl (or tropylium) ions previously observed for ortho-substituted diphenylcarbenium ions generated by electron ionisation. This reaction also occurs under low-energy collision conditions. Copyright 2000 John Wiley & Sons, Ltd.     

Comprehensive determination of trace elements in human saliva by ETA-AAS

A method is described for the comprehensive determination of a series of trace and ultratrace elements (Fe, Mn, Zn, Cu, Sr, Cr, Al and Si) in human saliva by atomic absorption spectrometry with electrothermal atomization and Zeeman-effect background correction. Procedures for sampling of total mixed saliva and its treatment including centrifugation and mineralization by HNO₃ are described in detail. To avoid the use of matrix modifiers, element standards with an artificial saliva matrix were used to construct calibration curves. Instrumental precision, tested by repeated analyses of natural salivas, is good (error less than 5%) for most elements. Lower precision was obtained for elements like Al and Si present in concentrations close to the detection limit. The analysis of some natural salivas clearly shows the influence of the sampling and treatment procedures on the reliability of the data. An accurate standardization of these procedures is thus recommended.     

Entire functions of exponential type bounded on the real axis and fourier transforms of distributions with bounded supports

On the complexification of the dual spaceE′ of a real Banach spaceE′ of infinite dimension, there is an entire complex valued function of exponential type, bounded onE′, hence slowly increasing onE′, which is not the Fourier transform of any distribution with bounded support onE. Partially supported by the Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, GB, Brasil and by the National Science Foundation, Washington, DC, USA. Attendance at the International Symposium on Partial Differential Equations and the Geometry of Normed Spaces was possible in part thanks to a grant from CAPES, Brasil.     

[1,3‐Bis(di­phenyl­phosphino)prop­ane]­tri­chloro­oxorhenium(V)

Tri­chloro­oxo­[1,3‐prop­ane­diyl­bis­(di­phenyl­phosphine)‐P,P′]rhen­ium(V), [Re­Cl₃­O­(C₂₇­H₂₆P₂)], crystallizes with four formula units per unit cell. The crystal structure consists of neutral complexes of [ReOCl₃(dppp)] [dppp is 1,3‐bis(diphenylphosphino)propane] packed by H?π‐ring interactions. The Re atom is octahedrally coordinated to the oxo anion, three Cl atoms and two P atoms from the dppp ligand. The six‐membered ring formed by the bidentate dppp ligand and the rhenium metal centre is in a chair conformation. The title compound is an intermediate in the synthesis of bis(dppp) complexes of rhenium.     

Functional magnetic resonance imaging: Comparison between activation maps and computation pipelines in a clinical context

In this study new evaluation strategies for comparing different Statistical Parametric Maps computed from fMRI time-series analysis software tools are proposed. The aim of our work is to assess and quantitatively evaluate the statistical agreement of activation maps. Some pre-processing steps are necessary to compare SPMs (Statistical Parametric Maps), including segmentation and co-registration. The study of the statistical agreement is carried out following two ways. The first way considers SPMs as the result of two classification processes and extracts confusion matrix and Cohen's kappa index to assess agreement. Some considerations will be made on the statistical dependence of classes and a new formulation of kappa index will be used for overcoming this problem. The second way considers SPMs as two 3D images, and computes the similarity of SPMs images with a fuzzy formulation of the Jaccard Index. Several experiments were conducted both to assess the performance of the proposed evaluation tools and to compare activation maps computation pipelines from two widely used software tools in a clinical context.     

Molecular dynamics of electrosprayed water nanodroplets containing sodium bis(2‐ethylhexyl)sulfosuccinate

The behavior of aqueous solutions of sodium bis(2‐ethylhexyl)sulfosuccinate (AOTNa) subject to electrospray ionization (ESI) has been investigated by molecular dynamics (MD) simulations at three temperatures (350, 500 and 800 K). We consider several types of water nanodroplets containing AOTNa molecules and composed of a fixed number of water molecules (1000), N⁰_AOT AOT^? anions (N⁰_AOT = 0, 5, 10) and N⁰_Na sodium ions (N⁰_Na = 0, 5, 10, 15, 20): in a short time scale (less than 1 ns), the AOTNa molecules, initially forming direct micelles in the interior of the water nanodroplets, are observed in all cases to diffuse nearby the nanodroplet surface, so that the hydrophilic heads and sodium ions become surrounded by water molecules, whereas the alkyl chains lay at the droplet surface. Meanwhile, evaporation of water molecules and of solvated sodium ions occurs, leading to a decrease of the droplet size and charge. At 350 K, no ejection of neutral or charged surfactant molecules is observed, whereas at 500 K, some fragmentation occurs, and at 800 K, this event becomes more frequent. The interplay of all these processes, which depend on the values of temperature, N⁰_AOT and N⁰_Na eventually leads to anhydrous charged surfactant aggregates with prevalence of monocharged ones, in agreement with experimental results of ESI mass spectrometry. The quantitative analysis of the MD trajectories allows to evidence molecular details potentially useful in designing future ESI experimental conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Apertureless near-field vibrational imaging of block-copolymer nanostructures with ultrahigh spatial resolution.

Nanodomains formed by microphase separation in thin films of the diblock copolymers poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) and poly(styrene-b-ethyleneoxide) (PS-b-PEO) were imaged by means of infrared scattering-type near-field microscopy. When probing at 3.39 mum (2950 cm(-1)), contrast is obtained due to spectral differences between the C--H stretching vibrational resonances of the respective polymer constituents. An all-optical spatial resolution better than 10 nm was achieved, which corresponds to a sensitivity of just several thousand C--H groups facilitated by the local-field enhancement at the sharp metallic probe tips. The results demonstrate that infrared spectroscopy with access to intramolecular dimensions is within reach.     

Stability of the residual free bubble method for bilinear finite elements on rectangular grids

We consider the nature of the stabilizing term arising in theresidual free bubble approach for piecewise bilinear functionson rectangular grids. We show, that on the subspace of piecewiselinear functions the stabilizing term is identical to that inthe streamline diffusion approach. However, on the space ofpiecewise bilinear functions there is a case in which the stabilizingterm is weaker compared to the term used in the streamline diffusionmethod. In the particular case when the direction of the convectionis parallel to a diagonal of the quadrilateral, control is lostover the mixed derivatives in the convection-dominated limit.