18,298 research outputs found

    An aseismic slip pulse in northern Chile and along-strike variations in seismogenic behavior

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    We use interferometric synthetic aperture radar, GPS, and seismic observations spanning 5 to 18 years to reveal a detailed kinematic picture of the spatiotemporal evolution of fault slip in a region corresponding to the 30 July 1995 M_w 8.1 subduction zone megathrust earthquake in northern Chile. In a single area, we document a complex mosaic of phenomena including large earthquakes, postseismic afterslip with a spatial distribution that appears to be tied to variations in coastal morphology, and a completely aseismic pulse that may have triggered a M_w 7.1 earthquake on 30 January 1998. In contrast to simple models of fault slip behavior, this spatial heterogeneity indicates that frictional parameters on the fault do not have a systematic transition with depth and also vary rapidly along strike. The low amount of afterslip from the M_w 8.1 earthquake relative to other similar events suggests that postseismic behavior may be modulated by the amount of sediment subducted

    Distribution of slip from 11 M_w > 6 earthquakes in the northern Chile subduction zone

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    We use interferometric synthetic aperture radar, GPS, and teleseismic data to constrain the relative location of coseismic slip from 11 earthquakes on the subduction interface in northern Chile (23°–25°S) between the years 1993 and 2000. We invert body wave waveforms and geodetic data both jointly and separately for the four largest earthquakes during this time period (1993 M_w 6.8; 1995 M_w 8.1; 1996 M_w 6.7; 1998 M_w 7.1). While the location of slip in the teleseismic-only, geodetic-only, and joint slip inversions is similar for the small earthquakes, there are differences for the 1995 M_w 8.1 event, probably related to nonuniqueness of models that fit the teleseismic data. There is a consistent mislocation of the Harvard centroid moment tensor locations of many of the 6 6 earthquakes, as well as three M_w > 7 events from the 1980s. All of these earthquakes appear to rupture different portions of the fault interface and do not rerupture a limited number of asperities

    An Introduction: Quantification of the Hippocampal BDNF Content of Maternally Separated Rats Using a Western Blot Protocol

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    Among industrialized nations, the United States has the worst incidence of child maltreatment with 3 million cases per year (U.S. Department of Health and Human Services, 2012). Studies have shown that individuals who were maltreated when they were young are more susceptible to drug abuse such as alcohol, cocaine, and nicotine (Maddahian, Newcomb, & Bentle, 1988). Early life stress (ELS) causes hyperactivation of the Hypothalamic-Pituitary- Adrenal (HPA) Axis (Heim et al., 2000; Plotsky et al., 2005). The dysregulation of the HPA axis causes the secretion of glucocorticoid stress hormones by large amounts, which in return attenuates hippocampal Brain-derived neurotrophic factor (BDNF) (Smith, Makino, Kvetnansky, & Post, 1995). BDNF is a neurotrophin that helps the growth, maintenance, and survival of neurons and is also involved in neuronal plasticity. To mimic ELS, maternal separation is used as an animal model. Studies have shown that adult maternally separated rats have decreased hippocampal mature BDNF (Lippman et al., 2007). Exercise alters some of the effects of ELS by protecting hippocampal BDNF from the down-regulation caused by the hyperactivation of HPA axis (Maniam & Morris, 2010; Neeper et al., 1996). The purpose of this research is to investigate the effects of ELS and exercise on behaviors related to substance abuse and hippocampal BDNF content. When we attempted to measure hippocampal BDNF by the enzyme-linked immunosorbent assay (ELISA), we did not observe the previously-published down-regulation of BDNF in the hippocampi of maternally separated animals (Dold, 2013). Thus, a western blot protocol was developed for the quantification of BDNF in the same protein samples that were previously quantified using ELISA. Western blot is more specific in targeting protein due to SDS-page capability to separate protein components in accordance to their size. BDNF undergoes post-translational processing, such that both pro- BDNF (the 32 kD precursor) and mature BDNF (14 kD) are present and biologically active in rat brain tissue. Thus, western blot will allow us to distinguish between these BDNF proteins, which is important in our study since we are primarily interested in mature BDNF. We expect maternal separation (MS) to attenuate the hippocampal mature BDNF content. Furthermore, we expect that the mature BDNF content will positively correlate with the total running activity

    Differential equation based method for accurate approximations in optimization

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    A method to efficiently and accurately approximate the effect of design changes on structural response is described. The key to this method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in most cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacements are used to approximate bending stresses

    Measurement of Holmium Rydberg series through MOT depletion spectroscopy

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    We report measurements of the absolute excitation frequencies of 165^{165}Ho 4f116sns4f^{11}6sns and 4f116snd4f^{11}6snd odd-parity Rydberg series. The states are detected through depletion of a magneto-optical trap via a two-photon excitation scheme. Measurements of 162 Rydberg levels in the range n=40101n=40-101 yield quantum defects well described by the Rydberg-Ritz formula. We observe a strong perturbation in the nsns series around n=51n=51 due to an unidentified interloper at 48515.47(4) cm1^{-1}. From the series convergence, we determine the first ionization potential EIP=48565.939(4)E_\mathrm{IP}=48565.939(4) cm1^{-1}, which is three orders of magnitude more accurate than previous work. This work represents the first time such spectroscopy has been done in Holmium and is an important step towards using Ho atoms for collective encoding of a quantum register.Comment: 6 figure

    Immune Responses in Human Necatoriasis: Association between Interleukin-5 Responses and Resistance to Reinfection

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    Cytokine and proliferative responses to Necator americanus infection were measured in a treatment-reinfection study of infected subjects from an area of Papua New Guinea where N. americanus is highly endemic. Before treatment, most subjects produced detectable interleukin (IL)4 (97%), IL-5 (86%), and interferon (IFN)-γ(64%) in response to adult N. americanus antigen. Pretreatment IFN-γ responses were negatively associated with hookworm burden, decreasing by 18 pg/mL for each increase of 1000 eggs/gram (epg) (n = 75; P < .01). Mean IFN-γ responses increased significantly after anthelmintic treatment, from 166 to 322 pg/mL (n = 42; P < .01). The intensity of reinfection was significantly negatively correlated with pretreatment IL-5 responses, decreasing by 551 epg for each 100 pg/mL increase in production of IL-5 (n = 51; P < .01). These data indicate that there is a mixed cytokine response in necatoriasis, with worm burdenassociated suppression of IFN-γ responses to adult N. americanus antigen. Resistance to reinfection is associated with the parasite-specific IL-5 response

    Hybrid Atom--Photon Quantum Gate in a Superconducting Microwave Resonator

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    We propose a novel hybrid quantum gate between an atom and a microwave photon in a superconducting coplanar waveguide cavity by exploiting the strong resonant microwave coupling between adjacent Rydberg states. Using experimentally achievable parameters gate fidelities >0.99> 0.99 are possible on sub-μ\mus timescales for waveguide temperatures below 40 mK. This provides a mechanism for generating entanglement between two disparate quantum systems and represents an important step in the creation of a hybrid quantum interface applicable for both quantum simulation and quantum information processing.Comment: 4 pages, 4 figure

    "Public Honours for Panhellenic Sporting Victors in Democratic Athens"

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    The treatment of Panhellenic victors by democratic Athens requires careful explanation. This city gave citizens who were victorious at the Olympics or one of the other three Panhellenic games for life free public dining and free front-row seats at its own local games. These honours were otherwise only given to victorious generals and other significant benefactors. Leslie Kurke argued that the granting of such honours to Panhellenic victors was part of the so-called economy of kudos, which, she believed, was a magical power which a sportsman gained forever in his victory. For Kurke a city honoured a victor as generously as it did because of his willingness to use his kudos in support of its military campaigns and other risky ventures. But in the last several years her theory has been largely refuted. Kudos was not a power which a victor had forever. It was the fleeting aid which a deity had given him during his agōn or contest. Alternative explanations making better sense of the evidence can be advanced for the roles of victors in the ventures which Kurke highlighted. The extraordinary honours which classical Athens gave a Panhellenic victory can instead be explained in terms of his victory’s political value. Thomas Heine Nielsen has put beyond doubt that each Panhellenic sportsman competed as a representative of his polis. Thus the Olympic victory of one of its citizens gave a city of no importance rare international prominence and one which was a regional power proof of its superiority over its rivals. The only other way which it had to raise its standing was to defeat a rival in battle. Like other Greek cities, then, classical Athens judged a Panhellenic victor worthy of its highest honours, because he had raised its standing without the need for it to take the field
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