727 research outputs found

    Stabilizing stick-slip friction

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    Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase-locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality.Comment: 4 pages, 4 figure

    Tuning friction with composite hierarchical surfaces

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    N.M.P. is supported by the European Research Council PoC 2015 “Silkene” No. 693670, by the European Commission H2020 under the Graphene Flagship Core 1 No. 696656 (WP14 “Polymer Nanocomposites”) and FET Proactive “Neurofibres” grant No. 732344. G.C. and F.B. are supported by H2020 FET Proactive “Neurofibres” grant No. 732344

    Direct and imagined contact moderates the effect of need for cognitive closure on attitudes towards women managers

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    This research investigated the relationship between individual preference for the need for cognitive closure (NCC) and attitudes towards women as managers and the moderating role of direct or imagined contact with women leaders. In two studies (total N = 369) collected in different countries and with different methods (Study 1: Italy, correlational; Study 2: U.S., experimental), it was found that the positive relationship between NCC and negative attitudes towards women as managers was moderated by the quality, but not the quantity of current or past direct contact experiences with women managers. In Study 1, employees with higher scores on NCC had more positive attitudes towards women managers when they had more positive work experience with women managers. In Study 2, those with higher NCC scores had less negative attitudes towards women as managers when they merely imagined (positive) contact with them (vs. a control group). These results advance the literature on the interaction between NCC and positive intergroup contact; theoretical and practical implications of NCC and positive intergroup contact are presented

    The value of risk in real estate markets

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    In this article we test the urban asset pricing model of Capozza and Sick (1988) and focus on the empirical dimensions of the effects of risk on urban land prices. The effects of systematic and unsystematic risk are distinguished in the model which incorporates the value of the option to convert land to urban uses into the pricing of urban real estate. We find the value of systematic risk in our Canadian urban areas to be negative and highly statistically significant. We find that approximately 2.5 percent of the value of houses in our sample arises from systematic risk. In our sample, unsystematic risk is a larger proportion of total risk than systematic risk. Therefore, most of the effect of total risk may be ascribed to unsystematic risk. The effect of total risk on land prices is illustrated through the irreversibility premia estimates. These premia vary greatly in size and statistical significance. Thus, the effect of unsystematic risk is highly city specific. In the two regions where the irreversibility premia are statistically significant, it accounts for 22 percent and 53 percent of the average housing price; thus, unsystematic risk can be a very important determinant of housing prices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47767/1/11146_2004_Article_BF00216587.pd

    Vegetarian and vegan weaning of the infant: How common and how evidence-based? a population-based survey and narrative review

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    Background: Vegetarian and vegan weaning have increasing popularity among parents and families. However, if not correctly managed, they may lead to wrong feeding regimens, causing severe nutritional deficiencies requiring specific nutritional support or even the need for hospitalization. Aim: To assess the prevalence of vegetarian and vegan weaning among Italian families and to provide an up-to-date narrative review of supporting evidence. Materials and methods: We investigated 360 Italian families using a 40-item questionnaire. The narrative review was conducted searching scientific databases for articles reporting on vegetarian and vegan weaning. Results: 8.6% of mothers follow an alternative feeding regimen and 9.2% of infants were weaned according to a vegetarian or vegan diet. The breastfeeding duration was longer in vegetarian/vegan infants (15.8 vs. 9.7 months; p < 0.0001). Almost half of parents (45.2%) claim that their pediatrician was unable to provide sufficient information and adequate indications regarding unconventional weaning and 77.4% of parents reported the pediatrician’s resistance towards alternative weaning methods. Nine studies were suitable for the review process. The vast majority of authors agree on the fact that vegetarian and vegan weaning may cause severe nutritional deficiencies, whose detrimental effects are particularly significant in the early stages of life. Discussion and conclusion: Our results show that alternative weaning methods are followed by a significant number of families; in half of the cases, the family pediatrician was not perceived as an appropriate guide in this delicate process. To date, consistent findings to support both the safety and feasibility of alternative weaning methods are still lacking. Since the risk of nutritional deficiencies in the early stages of life is high, pediatricians have a pivotal role in guiding parents and advising them on the most appropriate and complete diet regimen during childhood. Efforts should be made to enhance nutritional understanding among pediatricians as an unsupervised vegetarian or vegan diet can cause severe nutritional deficiencies with possible detrimental long-term effects

    Realtime calibration of the A4 electromagnetic lead fluoride calorimeter

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    Sufficient energy resolution is the key issue for the calorimetry in particle and nuclear physics. The calorimeter of the A4 parity violation experiment at MAMI is a segmented calorimeter where the energy of an event is determined by summing the signals of neighbouring channels. In this case the precise matching of the individual modules is crucial to obtain a good energy resolution. We have developped a calibration procedure for our total absorbing electromagnetic calorimeter which consists of 1022 lead fluoride (PbF_2) crystals. This procedure reconstructs the the single-module contributions to the events by solving a linear system of equations, involving the inversion of a 1022 x 1022-matrix. The system has shown its functionality at beam energies between 300 and 1500 MeV and represents a new and fast method to keep the calorimeter permanently in a well-calibrated state

    A Chemical Strategy for the Preparation of Multimodified Peptide Imaging Probes

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    Multimodality probes appear of great interest for innovative imaging applications in disease diagnosis. Herein, we present a chemical strategy enabling site-specific doublemodification and cyclization of a peptide probe exploiting native chemical ligation (NCL) and thiol-maleimide addition. The synthetic strategy is straightforward and of general applicability for the development of double-labeled peptide multimodality probes
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