2,593 research outputs found

    Error Signals from the Brain: 7th Mismatch Negativity Conference

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    The 7th Mismatch Negativity Conference presents the state of the art in methods, theory, and application (basic and clinical research) of the MMN (and related error signals of the brain). Moreover, there will be two pre-conference workshops: one on the design of MMN studies and the analysis and interpretation of MMN data, and one on the visual MMN (with 20 presentations). There will be more than 40 presentations on hot topics of MMN grouped into thirteen symposia, and about 130 poster presentations. Keynote lectures by Kimmo Alho, Angela D. Friederici, and Israel Nelken will round off the program by covering topics related to and beyond MMN

    Control of sand flies with attractive toxic sugar baits (ATSB) and potential impact on non-target organisms in Morocco

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    International audienceBackground: The persistence and geographical expansion of leishmaniasis is a major public health problem that requires the development of effective integrated vector management strategies for sand fly control. Moreover, these strategies must be economically and environmentally sustainable approaches that can be modified based on the current knowledge of sand fly vector behavior. The efficacy of using attractive toxic sugar baits (ATSB) for sand fly control and the potential impacts of ATSB on non-target organisms in Morocco was investigated. Methods: Sand fly field experiments were conducted in an agricultural area along the flood plain of the Ourika River. Six study sites (600 m x 600 m); three with ``sugar rich'' (with cactus hedges bearing countless ripe fruits) environments and three with ``sugar poor'' (green vegetation only suitable for plant tissue feeding) environments were selected to evaluate ATSB, containing the toxin, dinotefuran. ATSB applications were made either with bait stations or sprayed on non-flowering vegetation. Control sites were established in both sugar rich and sugar poor environments. Field studies evaluating feeding on vegetation treated with attractive (non-toxic) sugar baits (ASB) by non-target arthropods were conducted at both sites with red stained ASB applied to non-flowering vegetation, flowering vegetation, or on bait stations. Results: At both the sites, a single application of ATSB either applied to vegetation or bait stations significantly reduced densities of both female and male sand flies (Phlebotomus papatasi and P. sergenti) for the five-week trial period. Sand fly populations were reduced by 82.8% and 76.9% at sugar poor sites having ATSB applied to vegetation or presented as a bait station, respectively and by 78.7% and 83.2%, respectively at sugar rich sites. The potential impact of ATSB on non-targets, if applied on green non-flowering vegetation and bait stations, was low for all non-target groups as only 1% and 0.7% were stained with non-toxic bait respectively when monitored after 24 hours. Conclusions: The results of this field study demonstrate ATSB effectively controls both female and male sand flies regardless of competing sugar sources. Furthermore, ATSB applied to foliar vegetation and on bait stations has low non-target impact

    Demagnetization via Nucleation of the Nonequilibrium Metastable Phase in a Model of Disorder

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    We study both analytically and numerically metastability and nucleation in a two-dimensional nonequilibrium Ising ferromagnet. Canonical equilibrium is dynamically impeded by a weak random perturbation which models homogeneous disorder of undetermined source. We present a simple theoretical description, in perfect agreement with Monte Carlo simulations, assuming that the decay of the nonequilibrium metastable state is due, as in equilibrium, to the competition between the surface and the bulk. This suggests one to accept a nonequilibrium "free-energy" at a mesoscopic/cluster level, and it ensues a nonequilibrium "surface tension" with some peculiar low-T behavior. We illustrate the occurrence of intriguing nonequilibrium phenomena, including: (i) Noise-enhanced stabilization of nonequilibrium metastable states; (ii) reentrance of the limit of metastability under strong nonequilibrium conditions; and (iii) resonant propagation of domain walls. The cooperative behavior of our system may also be understood in terms of a Langevin equation with additive and multiplicative noises. We also studied metastability in the case of open boundaries as it may correspond to a magnetic nanoparticle. We then observe burst-like relaxation at low T, triggered by the additional surface randomness, with scale-free avalanches which closely resemble the type of relaxation reported for many complex systems. We show that this results from the superposition of many demagnetization events, each with a well- defined scale which is determined by the curvature of the domain wall at which it originates. This is an example of (apparent) scale invariance in a nonequilibrium setting which is not to be associated with any familiar kind of criticality.Comment: 26 pages, 22 figure

    Aharonov-Bohm Oscillations in a One-Dimensional Wigner Crystal-Ring

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    We calculate the magnetic moment (`persistent current') in a strongly correlated electron system --- a Wigner crystal --- in a one-dimensional ballistic ring. The flux and temperature dependence of the persistent current in a perfect ring is shown to be essentially the same as for a system of non-interacting electrons. In contrast, by incorporating into the ring geometry a tunnel barrier that pins the Wigner crystal, the current is suppressed and its temperature dependence is drastically changed. The competition between two temperature effects --- the reduced barrier height for macroscopic tunneling and loss of quantum coherence --- may result in a sharp peak in the temperature dependence. The character of the macroscopic quantum tunneling of a Wigner crystal ring is dictated by the strength of pinning. At strong pinning the tunneling of a rigid Wigner crystal chain is highly inhomogeneous, and the persistent current has a well-defined peak at T0.5 s/LT\sim 0.5\ \hbar s/L independent of the barrier height (ss is the sound velocity of the Wigner crystal, LL is the length of the ring). In the weak pinning regime, the Wigner crystal tunnels through the barrier as a whole and if Vp>T0V_p>T_0 the effect of the barrier is to suppress the current amplitude and to shift the crossover temperature from T0T_0 to TVpT0T^*\simeq \sqrt{V_{p}T_{0}}. (VpV_{p} is the amplitude of the pinning potential, T0=vF/L,  vF/maT_{0} =\hbar v_{F}/L ,\; v_{F}\sim \hbar/ma is the drift velocity of a Wigner crystal ring with lattice spacing aa). For very weak pinning, VpT0V_p\ll T_0, the influence of the barrier on the persistent current of a Wigner crystal ring is negligibly small.Comment: 30 pages, RevTeX, 2 figures available on reques

    DN interaction from meson exchange

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    A model of the DN interaction is presented which is developed in close analogy to the meson-exchange KbarN potential of the Juelich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box diagrams involving D*N, D\Delta, and D*\Delta intermediate states. The coupling of DN to the pi-Lambda_c and pi-Sigma_c channels is taken into account. The interaction model generates the Lambda_c(2595) resonance dynamically as a DN quasi-bound state. Results for DN total and differential cross sections are presented and compared with predictions of an interaction model that is based on the leading-order Weinberg-Tomozawa term. Some features of the Lambda_c(2595) resonance are discussed and the role of the near-by pi-Sigma_c threshold is emphasized. Selected predictions of the orginal KbarN model are reported too. Specifically, it is pointed out that the model generates two poles in the partial wave corresponding to the Lambda(1405) resonance.Comment: 14 pages, 8 figure

    HER2 and ESR1 mRNA expression levels and response to neoadjuvant trastuzumab plus chemotherapy in patients with primary breast cancer

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    Introduction: Recent data suggest that benefit from trastuzumab and chemotherapy might be related to expression of HER2 and estrogen receptor (ESR1). Therefore, we investigated HER2 and ESR1 mRNA levels in core biopsies of HER2-positive breast carcinomas from patients treated within the neoadjuvant GeparQuattro trial. Methods: HER2 levels were centrally analyzed by immunohistochemistry (IHC), silver in-situ hybridization (SISH) and qRT-PCR in 217 pretherapeutic formalin-fixed, paraffin-embedded (FFPE) core biopsies. All tumors had been HER2-positive by local pathology and had been treated with neoadjuvant trastuzumab/ chemotherapy in GeparQuattro. Results: Only 73% of the tumors (158 of 217) were centrally HER2-positive (cHER2-positive) by IHC/SISH, with cHER2-positive tumors showing a significantly higher pCR rate (46.8% vs. 20.3%, p<0.0005). HER2 status by qRT-PCR showed a concordance of 88.5% with the central IHC/SISH status, with a low pCR rate in those tumors that were HER2-negative by mRNA analysis (21.1% vs. 49.6%, p<0.0005). The level of HER2 mRNA expression was linked to response rate in ESR1-positive tumors, but not in ESR1-negative tumors. HER2 mRNA expression was significantly associated with pCR in the HER2-positive/ESR1-positive tumors (p=0.004), but not in HER2-positive/ESR1-negative tumors. Conclusions: Only patients with cHER2-positive tumors - irrespective of the method used - have an increased pCR rate with trastuzumab plus chemotherapy. In patients with cHER2-negative tumors the pCR rate is comparable to the pCR rate in the non-trastuzumab treated HER-negative population. Response to trastuzumab is correlated to HER2 mRNA levels only in ESR1-positive tumors. This study adds further evidence to the different biology of both subsets within the HER2-positive group
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