532 research outputs found

    Management of cluster headache in the emergency department

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    Although cluster headache (CH) is considered one of the most distinctive and painful primary headache disorders in clinical practice because of the brevity of each attack, its management is not always ergonomic or possible in the Emergency Department. In case of a previously competent diagnosis, the Emergency Department's team should send the patient to a headache centre where specialists in the management of CH can handle the pathology in the best way. In our headache centre we treat patients with CH attacks with a hyperbaric chamber, confirming the effectiveness of hyperbaric oxygen in CH patients. © Springer-Verlag Italia 2005

    Estimation of the variance in any point of an electron-density map for any space group

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    In a recent paper [Giacovazzo & Mazzone (2011). Acta Cryst. A67, 210-218] a mathematical expression of the variance at any point of the unit cell has been described. The formulas were derived in P1 for any type of Fourier synthesis (observed, difference and hybrid) under the following hypothesis: the current phases are distributed on the trigonometric circle about the correct values according to von Mises distributions. This general hypothesis allows the variance expressions to be valid at any stage of the phasing process. In this paper the method has been extended to any space group, no matter whether centric or acentric. The properties of the variance generated by space-group symmetry are described; in particular it is shown that the variance is strictly connected with the implication transformations, which are basic for Patterson deconvolution. General formulas simultaneously taking into account phase uncertainty and measurement errors have been obtained, valid no matter what the quality of the model

    Detecting Neutrino Magnetic Moments with Conducting Loops

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    It is well established that neutrinos have mass, yet it is very difficult to measure those masses directly. Within the standard model of particle physics, neutrinos will have an intrinsic magnetic moment proportional to their mass. We examine the possibility of detecting the magnetic moment using a conducting loop. According to Faraday's Law of Induction, a magnetic dipole passing through a conducting loop induces an electromotive force, or EMF, in the loop. We compute this EMF for neutrinos in several cases, based on a fully covariant formulation of the problem. We discuss prospects for a real experiment, as well as the possibility to test the relativistic formulation of intrinsic magnetic moments.Comment: 6 pages, 4 b/w figures, uses RevTe

    Random projections and the optimization of an algorithm for phase retrieval

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    Iterative phase retrieval algorithms typically employ projections onto constraint subspaces to recover the unknown phases in the Fourier transform of an image, or, in the case of x-ray crystallography, the electron density of a molecule. For a general class of algorithms, where the basic iteration is specified by the difference map, solutions are associated with fixed points of the map, the attractive character of which determines the effectiveness of the algorithm. The behavior of the difference map near fixed points is controlled by the relative orientation of the tangent spaces of the two constraint subspaces employed by the map. Since the dimensionalities involved are always large in practical applications, it is appropriate to use random matrix theory ideas to analyze the average-case convergence at fixed points. Optimal values of the gamma parameters of the difference map are found which differ somewhat from the values previously obtained on the assumption of orthogonal tangent spaces.Comment: 15 page

    Ab initio Direct Phasing in Macromolecular Crystallography: an Application of the Z-test

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    The z-criterion has been recently formulated as a tool for judging about the ab initio solvability of a crystal structure via direct methods. The criterion is reconsidered to take into account the recent powerful techniques of phase refinement in direct and reciprocal space. A report is made on a medium size crystal structure, recently solved by SIR97 by the pure application of the tangent formula

    Phasing diffuse scattering. Application of the SIR2002 algorithm to the non-crystallographic phase problem

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    A new phasing algorithm has been used to determine the phases of diffuse elastic X-ray scattering from a non-periodic array of gold balls of 50 nm diameter. Two-dimensional real-space images, showing the charge-density distribution of the balls, have been reconstructed at 50 nm resolution from transmission diffraction patterns recorded at 550 eV energy. The reconstructed image fits well with scanning electron microscope (SEM) image of the same sample. The algorithm, which uses only the density modification portion of the SIR2002 program, is compared with the results obtained via the Gerchberg-Saxton-Fienup HIO algorithm. In this way the relationship between density modification in crystallography and the HiO algorithm used in signal and image processing is elucidated.Comment: 7 pages, 12 figure

    Analytical evaluation of atomic form factors: application to Rayleigh scattering

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    Atomic form factors are widely used for the characterization of targets and specimens, from crystallography to biology. By using recent mathematical results, here we derive an analytical expression for the atomic form factor within the independent particle model constructed from nonrelativistic screened hydrogenic wavefunctions. The range of validity of this analytical expression is checked by comparing the analytically obtained form factors with the ones obtained within the Hartee-Fock method. As an example, we apply our analytical expression for the atomic form factor to evaluate the differential cross section for Rayleigh scattering off neutral atoms.Comment: 7 pages, 1 figur

    Solvent content of protein crystals from diffraction intensities by Independent Component Analysis

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    An analysis of the protein content of several crystal forms of proteins has been performed. We apply a new numerical technique, the Independent Component Analysis (ICA), to determine the volume fraction of the asymmetric unit occupied by the protein. This technique requires only the crystallographic data of structure factors as input.Comment: 9 pages, 2 figures, 1 tabl

    A New Portable XRD/XRF Instrument for Non-destructive Analysis

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    A new integrated portable apparatus capable of in situ X-ray diffraction (XRD) and X-ray fluorescence (XRF) measurements is presented. The instrument equipment is based on a Theta-Theta horizontal goniometer projected and developed in order to optimize stability and reliability for apparatus of such a reduced size and capable of capturing both XRF and XRD information. The simultaneous XRD/XRF data collection is achieved by using a Si solid state detector counting the X-ray photons scattered from the sample as a function of both the energy and the angular step. The instrument is also equipped with a software developed in order to provide both ease of operation in the data collection and a complete and fast characterization of the materials in the data analysis

    Anisakis Allergy: Is Aquacultured Fish a Safe and Alternative Food to Wild-Capture Fisheries for Anisakis simplex-Sensitized Patients?

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    Background: Anisakis simplex (A. simplex) infection, in humans, causes a series of clinical manifestations affecting the gastro-intestinal tract known as Anisakiasis/Anisakidosis. Patients may also present allergic manifestations such as hives and/or angioedema and even anaphylactic shock. The aim of this study was to investigate whether aquacultured fish could be considered A.simplex-free food and constitute a safe, alternative, wild-capture fish food for Gastro-Allergic Anisakiasis (GAA)-sensitized subjects. Methods: Protein extracts from A. simplex larvae in the third stage (L3) and from edible part of heavily infected horse mackerel (Trachurus trachurus) and aquacultured sea bream, have been tested for A. simplex allergens presence by immunological analysis. Western blot analysis using, as source of specific Anisakis allergens antibodies, serum samples from subjects referring allergic symptoms after raw fish ingestion, was performed. These subjects showed high levels of specific IgE anti A.simplex allergens determined by clinical laboratory tests (ISAC test). Results: Our data demonstrate the presence of Ani s4 allergen in both infected and aquacultured fish extracts, providing a possible interpretation for the allergic manifestations reported by subjects, already sensitized to A. simplex, who ate frozen or well-cooked or, even, aquacultured fish. Conclusions: The present data stimulate more accurate prophylaxis suggestions for Anisakis allergy and more specific controls of fishmeal used in aquaculture
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