9,456 research outputs found

    Inducing false memories by manipulating memory self-efficacy

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    The aim of this paper is to investigate the relationship between self-efficacy and false memories using the Deese/Roediger–McDermott (DRM) paradigm, whereby people falsely remember words not presented in lists. In two studies participants were presented with DRM lists and asked to recall and recognize presented items. In the first study, we found a significant relationship between memory self-efficacy (MSE) and susceptibility to associative memory illusions, both in recall and recognition. They also received the Memory Self-Efficacy Questionnaire (MSEQ), the Big Five Questionnaire (BFQ) and the backward digit span (BDS) test. In the second study, MSE was manipulated in order to assess whether changes influenced the sensitivity parameter in DRM tasks. Results showed that the manipulation was effective in decreasing self-efficacy, which in turn affected the probability of reporting critical lures as well as sensitivity. Possible explanations for the effect are discussed

    Bistability, softening, and quenching of magnetic moments in Ni-filled carbon nanotubes

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    The authors apply first-principles calculations to investigate the interplay between structural, electronic, and magnetic properties of nanostructures composed of narrow nanotubes filled with metallic nanowires. The focus is on the structural and magnetic responses of Ni-filled nanotubes upon radial compression. Interestingly, metastable flattened structures are identified, in which radially deformed nanotubes are stabilized by the interactions with the encapsulated wire. Moreover, our results indicate a quenching of the magnetic moment of the wire upon compression, as a result of the transfer of charge from the ss to the dd orbitals of the atoms in the wire.Comment: 4 pages, 4 figure

    High-resolution methods for fluorescence retrieval from space

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    The retrieval from space of a very weak fluorescence signal was studied in the O2A and O2B oxygen atmospheric absorption bands. The accuracy of the method was tested for the retrieval of the chlorophyll fluorescence and reflectance terms contributing to the sensor signal. The radiance at the top of the atmosphere was simulated by means of a commercial radiative-transfer program at a high resolution (0.1 cm-1). A test data set was generated in order to simulate sun-induced chlorophyll fluorescence at the top of the canopy. Reflectance terms were spectrally modeled using cubic splines and fluorescence by means of the sum of two Voigt functions. Sensor radiance residual minimization was performed in the presence of a multiplicative noise, thus ensuring that the sensor simulations were realistic. The study, which focused on the possibility of retrieving fluorescence with an accuracy better than 10%, was performed for instrument resolutions ranging from about 0.4 cm-1 to 2 cm-1 in order to test the algorithm for the characteristics of existing and planned hyper-spectral sensors. The algorithm was also used to retrieve fluorescence in the single O2A band at the OCO and TANSO-FTS instrument spectral resolution

    Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects

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    We report on a conceptually new test of the equivalence principle performed by measuring the acceleration in Earth's gravity field of two isotopes of strontium atoms, namely, the bosonic 88^{88}Sr isotope which has no spin vs the fermionic 87^{87}Sr isotope which has a half-integer spin. The effect of gravity upon the two atomic species has been probed by means of a precision differential measurement of the Bloch frequency for the two atomic matter waves in a vertical optical lattice. We obtain the values η=(0.2±1.6)×107\eta = (0.2\pm 1.6)\times10^{-7} for the E\"otv\"os parameter and k=(0.5±1.1)×107k=(0.5\pm1.1)\times10^{-7} for the coupling between nuclear spin and gravity. This is the first reported experimental test of the equivalence principle for bosonic and fermionic particles and opens a new way to the search for the predicted spin-gravity coupling effects.Comment: 5 pages, 4 figures. New spin-gravtity coupling analysis on the data added to the manuscrip

    Bragg gravity-gradiometer using the 1^1S0_0-3^3P1_1 intercombination transition of 88^{88}Sr

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    We present a gradiometer based on matter-wave interference of alkaline-earth-metal atoms, namely 88^{88}Sr. The coherent manipulation of the atomic external degrees of freedom is obtained by large-momentum-transfer Bragg diffraction, driven by laser fields detuned away from the narrow 1^1S0_0-3^3P1_1 intercombination transition. We use a well-controlled artificial gradient, realized by changing the relative frequencies of the Bragg pulses during the interferometer sequence, in order to characterize the sensitivity of the gradiometer. The sensitivity reaches 1.5×1051.5 \times 10^{-5} s2^{-2} for an interferometer time of 20 ms, limited only by geometrical constraints. We observed extremely low sensitivity of the gradiometric phase to magnetic field gradients, approaching a value 105^{5} times lower than the sensitivity of alkali-atom based gradiometers. An efficient double-launch technique employing accelerated red vertical lattices from a single magneto-optical trap cloud is also demonstrated. These results highlight strontium as an ideal candidate for precision measurements of gravity gradients, with potential application in future precision tests of fundamental physics.Comment: 10 pages, 7 figure

    The hypoxic transcription factor KlMga2 mediates the response to oxidative stress and influences longevity in the yeast Kluyveromyces lactis

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    Hypoxia is defined as the decline of oxygen availability, depending on environmental supply and cellular consumption rate. The decrease in O2 results in reduction of available energy in facultative aerobes. The response and/or adaptation to hypoxia and other changing environmental conditions can influence the properties and functions of membranes by modifying lipid composition. In the yeast Kluyveromyces lactis, the KlMga2 gene is a hypoxic regulatory factor for lipid biosynthesis-fatty acids and sterols-and is also involved in glucose signaling, glucose catabolism and is generally important for cellular fitness. In this work we show that, in addition to the above defects, the absence of the KlMGA2 gene caused increased resistance to oxidative stress and extended lifespan of the yeast, associated with increased expression levels of catalase and SOD genes. We propose that KlMga2 might also act as a mediator of the oxidative stress response/adaptation, thus revealing connections among hypoxia, glucose signaling, fatty acid biosynthesis and ROS metabolism in K. lactis

    Group theory analysis of electrons and phonons in N-layer graphene systems

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    In this work we study the symmetry properties of electrons and phonons in graphene systems as function of the number of layers. We derive the selection rules for the electron-radiation and for the electron-phonon interactions at all points in the Brillouin zone. By considering these selection rules, we address the double resonance Raman scattering process. The monolayer and bilayer graphene in the presence of an applied electric field are also discussed.Comment: 8 pages, 6 figure

    Late Quaternary monogenetic volcanoes along Río Salado, Sothwest Mendoza Province, Argentina

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    On the eastem flank of the Andes, to the north of Río Salado in southwest Mendoza Province (35º07'S-35º10'S), there are 4 monogenetic cones with blocky lava flows. A western group of small volcanoes, Hoyada, Lagunita and Loma Negra, with a total volume of -0.2 km3, are composed of amphibole-bearing basaltic andesite, and the eastem, more voluminous Hoyo Colorado volcano, with 0.44 km3 is composed of olivine (+ oxidised amphibole) basaltic andesite. Although data indicate they were emitted through successive, strombolian eruptions, they are overall coeval and the youngest Late Pleistocene volcanoes located in an "extra-Andean" setting, -70 km east of the main volcanic front. The magmas of the westem group of monogenetic cones show petrographic and geochemical characteristics that support processes of crustal interaction during ascent. In contrast, the magmas of the Hoyo Colorado volcano had a more direct ascent. Structural characteristics of the basement rocks to the volcanoes and the current seismotectonic activity of the Andes at this latitude indicate that the monogenetic cones of Río Salado were emplaced in a dominantly compressive tectonic regime

    Dietary Nitrate: Effects on the health of weaning pigs and Antimicrobial activity on seven probiotic Bifidobacterium spp. strains

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    The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology. It has been shown that nitrite, under the acidic conditions of the stomach, may kill gut pathogens like Salmonella enteritidis, Escherichia coli, Salmonella typhimurium, and Yersinia enterocolitica, whereas acid alone has only a bacteriostatic effect. An in vivo study was conducted in order to assess the effects of dietary nitrate on microbiota and on the health of the gut (particularly in the stomach and small intestine). 96 weaning pigs were fed a diet containing high nitrate levels (15 mg and 150 mg) and then challenged with Salmonella enterica serovar typhimurium. Differences in composition of the gut microbiota were assessed by analysing samples from the pigs: To date analysis of 48 pigs has been completed.. Preliminary results demonstrated no effect on the population densities of microbial groups either from the challenge or from nitrate intake. However, increasing the time from challenge decreased either the counts of LAB in the stomach and jejunum or of clostridia in the stomach. Bifidobacteria also decreased in the stomach contents as nitrate supplementation increased. Supplementing the feedstuff with high dietary nitrate intake and then challenging with Salmonella did not affect the gastric pH or the degree of ulceration in the pigs. The synergistic bactericidal effects of pH, nitrite and thiocyanate on seven probiotic Bifidobacterium spp. strains were also investigated in an in vitro study. The results of the in vitro study demonstrated that an inhibitory effect exists on the seven probiotic bifidobacteria investigated with an exposure longer than 2 hours and pH values < 5.0. Addition of thiocyanate also increased the susceptibility of the tested strains. In this in vitro study, the most resistant strains at all conditions were B. animalis subsp. lactis Ra 18 and P32 and B. choerinum Su 877, Su 837 and Su 891
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