2,856 research outputs found

    Recoverin Regulates Light-dependent Phosphodiesterase Activity in Retinal Rods

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    The Ca2+-binding protein recoverin may regulate visual transduction in retinal rods and cones, but its functional role and mechanism of action remain controversial. We compared the photoresponses of rods from control mice and from mice in which the recoverin gene was knocked out. Our analysis indicates that Ca2+-recoverin prolongs the dark-adapted flash response and increases the rod's sensitivity to dim steady light. Knockout rods had faster Ca2+ dynamics, indicating that recoverin is a significant Ca2+ buffer in the outer segment, but incorporation of exogenous buffer did not restore wild-type behavior. We infer that Ca2+-recoverin potentiates light-triggered phosphodiesterase activity, probably by effectively prolonging the catalytic activity of photoexcited rhodopsin

    How different Fermi surface maps emerge in photoemission from Bi2212

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    We report angle-resolved photoemission spectra (ARPES) from the Fermi energy (EFE_F) over a large area of the (kx,kyk_x,k_y) plane using 21.2 eV and 32 eV photons in two distinct polarizations from an optimally doped single crystal of Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} (Bi2212), together with extensive first-principles simulations of the ARPES intensities. The results display a wide-ranging level of accord between theory and experiment and clarify how myriad Fermi surface (FS) maps emerge in ARPES under various experimental conditions. The energy and polarization dependences of the ARPES matrix element help disentangle primary contributions to the spectrum due to the pristine lattice from those arising from modulations of the underlying tetragonal symmetry and provide a route for separating closely placed FS sheets in low dimensional materials.Comment: submitted to PR

    Selected topics on Hadrons in Nuclei

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    In this talk we report on selected topics on hadrons in nuclei. The first topic is the renormalization of the width of the Λ(1520)\Lambda(1520) in a nuclear medium. This is followed by a short update of the situation of the ω\omega in the medium. The investigation of the properties of Kˉ\bar{K} in the nuclear medium from the study of the (Kflight,p)(K_{flight},p) reaction is also addressed, as well as properties of X,Y,Z charmed and hidden charm resonances in a nuclear medium. Finally we address the novel issue of multimeson states.Comment: Talk at the International Nuclear Physics Conference, Vancouver, July 201

    Slow-Moving Landslide Damage Assessment of Historic Masonry Churches: Some Case-Studies in Italy

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    This paper presents a contribution for the damage assessment of historic masonry churches exposed to slow-moving landslides. In particular, the authors identified four global damage mechanisms, which are presented here by means of the critical damage assessment of four case studies located in the Liguria region (Italy) in areas affected by slow-moving landslides. For each church, a correlation between the damage patterns observed on-site and the ground movements induced by landslide phenomena was sought by means of visual inspections and crack interpretation. As a result, each damage mechanism was associated to a different pattern of ground movements produced by slow-moving landslides

    Measurement of 1323 and 1487 keV resonances in 15N({\alpha}, {\gamma})19F with the recoil separator ERNA

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    The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the {\alpha} and {\gamma} channels. We show that a direct measurement of the cross section of the ^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha} of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} . The revision of the widths of the two more relevant broad resonances in the 15N({\alpha},{\gamma})19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.Comment: 8 pages, 11 figures. Accepted for publication in PR

    Tratamiento de la escoliosis idiopática mediante artrodesis anterior e instrumentación de Zielke

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    —Hemos revisado 16 pacientes afectos de escoliosis toracolumbar y lumbar tratados mediante artrodesis anterior e instrumentación de Zielke. La corrección de la curva en el plano anteroposterior ha sido del 68%. La escoliosis torácica asociada se ha corregido de forma espontánea un 30%. La lordosis global final ha sido de 40°, sin embargo la instrumentación provoca un aumento de la cifosis regional de 10°. Las complicaciones de la serie han sido 3 roturas de barra, una progresión de la curva torácica y un derrame pleural.The authors showed the clinical outcome of 16 patients with thoracolumbar and lumbar curvatures treated by Zielke instrumentation and anterior fusion. The correction obtained in the primary curvature was 68%. The average correction in the compensatory thoracic curvature was 30%. The average lordosis correction at follow was 40°. However the Zielke's system lead to an increase of 10° of kyphotic at the instrumented levels. Complications included 3 browen rods, a progression of the thoracic curve and one pleural spilling

    Tallimustine in advanced previously untreated colorectal cancer, a phase II study.

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    Tallimustine is a novel benzoyl mustard derivative from distamycin A with a unique mode of action. It is a DNA minor groove binder and produces highly sequence-specific alkylations. Previous studies have shown significant anti-tumour effects in animal models. We performed a phase II study in previously untreated patients with advanced colorectal cancer, using a schedule of i.v. bolus infusions of 900 microgram m-2 once every 4 weeks. Seventeen patients were enrolled, and no responses were documented in 14 evaluable patients. Toxicity mainly consisted a highly selective neutropenia, which warrants further investigation of this agent in combination with myeloid growth factors

    Magnetic properties and energy absorption of CoFe2O4 nanoparticles for magnetic hyperthermia

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    We have studied the magnetic and power absorption properties of three samples of CoFe2O4 nanoparticles with sizes from 5 to 12 nm prepared by thermal decomposition of Fe (acac)3 and Co(acac)2 at high temperatures. The blocking temperatures TB estimated from magnetization M(T) curves spanned the range 180 < TB < 320 K, reflecting the large magnetocrystalline anisotropy of these nanoparticles. Accordingly, high coercive fields HC \approx 1.4 - 1.7 T were observed at low temperatures. Specific Power Absorption (SPA) experiments carried out in ac magnetic fields indicated that, besides particle volume, the effective magnetic anisotropy is a key parameter determining the absorption efficiency. SPA values as high as 98 W/g were obtained for nanoparticles with average size of \approx12 nm.Comment: 4 pages, 3 figure
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