170,008 research outputs found
Phenomenological Model of Rubber Bearings With Variable Axial Loading
No full textSeismic base isolation systems protect thousands of structures and infrastructures all over the world. Their effectiveness for seismic protection is widely recognized owing to acceleration reduction with a consequent minimization of the structural damage and of the “panic” effect for the occupants. This work deals with the development of a model for simulating the horizontal response of rubber bearings, extending an existent procedure to the case of variable axial loading. A consolidated procedure from literature, demonstrated able to correctly reproduce the complex mechanical behavior of rubber bearing isolation devices under constant axial loading, represents the starting point. Available laboratory cycling tests at variable axial load allow to illustrate the new numerical procedure. An optimization process, based on both automatic and user-driven procedures, is used to identify at different loading conditions the model parameters and the functions to model their variation. The proposed formulation overcomes the limits of the original model in this respect. The developed new procedure is shown to be capable of simulating with reasonable accuracy the experimentally observed cyclic behavior under coupled vertical-horizontal loading conditions, and the consequences in terms of the device response in the case of a seismic vertical-horizontal concurrent excitations are highlighted
Modelling the Response of Isolation Rubber Bearings with Variable Axial Loading
No full textSeismic base isolation systems protect thousands of structures and infrastructures all over the world.
Its effectiveness for seismic protection is widely recognized owing acceleration reduction and
minimization of the ‘panic’ effects for the occupants. This aspect has recently recognized of special
interests also for strategic structures and facilities for which superior performances expected.
This work deals with the development of a modified model for simulating the horizontal response of
rubber bearings, extending the existent procedures to variable axial loading. laboratory tests serve as
the target for developing the numerical formulation
Teaching and Cultural Otherness
No full textThis work focuses on the relational dimension of the encounter between teacher and students meant as a structural element for teaching practice. By using theoretical group-analytical and anthropo-analytical coordinates, the authors psychodynamically problematize some relational conditions that may influence learning. This research concentrates on the circumstances that limit and allow the birth of a group arrangement capable to learn from experience, rather than on a perspective to teach-learn in a perfect agreement with planning. Intercultural education is pointed out and located as a horizon and ideal term to guide educational practice
La quotidianità dell’incontro in classe: insegnamento e alterità
No full textIl presente lavoro si focalizza sulla dimensione relazionale dell’incontro tra docente e allievi intesa come elemento strutturale della pratica dell’insegnamento. Attraverso l’uso di coor- dinate teoriche di matrice gruppoanalitica e antropoanalitica gli autori problematizzano in sen- so psicodinamico alcune condizioni relazionali che vincolano e rendono possibile l’emersione di un assetto di gruppo volto ad apprendere dall’esperienza rispetto a un orizzonte immaginario perfettamente allineato sulla programmazione. L’orizzonte dell’educazione interculturale è indicato come termine ideale per orientare la prassi educativa.This work focuses on the relational dimension of meeting between teacher and students meant as structural element of teaching practice. By using group-analysis and anthropo-analysis theoretical coordinates, the authors psycho dynamically problematize some binding relational conditions which allow surfacing a group layout aimed at learning from experience with re- spect of an imaginary horizon in a perfect agreement with planning. The horizon of intercultural education is indicated as an ideal term to adjust educational practice
A SHARP model of bid–ask spread forecasts
No full textThis paper proposes an accurate, parsimonious and fast-to-estimate forecasting model for integer-valued time series with long memory and seasonality. The modelling is achieved through an autoregressive Poisson process with a predictable stochastic intensity that is determined by two factors: a seasonal intraday pattern and a heterogeneous autoregressive component. We call the model SHARP, which is an acronym for seasonal heterogeneous autoregressive Poisson. We also present a mixed-data sampling extension of the model, which adopts the historical information flow more efficiently and provides the best (among all the models considered) forecasting performances, empirically, for the bid-ask spreads of NYSE equity stocks. We conclude by showing how bid-ask spread forecasts based on the SHARP model can be exploited in order to reduce the total cost incurred by a trader who is willing to buy or sell a given amount of an equity stock. (C) 2019 International Institute of Forecasters. Published by Elsevier B.V. All rights reserved
Evaluation of frost resistance in oat
No full textResistance to biotic and abiotic stress is a crucial aspect for cultivar adaptation to agriculture environments. Among winter cereals, oat is the most frost sensitive and its insufficient level of winterhardiness is the main factor limiting sowing of winter oat in Northern Italy and Central Europe. Frost resistance, the most important component of winterhardiness, is an inducible process promoted by cold exposure and associated with a number of biochemical and molecular changes. We employed field tests and physiological parameters in a set of cultivars released during the last 40 years to explore the genetic variability in frost resistance and identify resistant genotypes. Plants were hardened at +3/+1°C and exposed to freezing temperatures. The efficiency of the excitation capture by open Photosystyem II (PSII) reaction centres was evaluated after freezing, through the chlorophyll fluorescence parameter Fv/Fm, according to Rizza et al. (2001). Different hardening length and pre-hardening temperature (+12/+7°C) were also employed to investigate if a higher level of resistance is associated with the ability to induce early hardening. This capacity is of advantage under field conditions, where temperature falls progressively, because it enables resistant plants to prepare for cold before the susceptible ones. Some significant molecular traits associated to frost resistance such as the accumulation of cor14 (Cattivelli et al., 1995) were also investigated on selected cultivars. Fv/Fm analysis appears as an attractive test being rapid, non invasive and able to monitor a trait related to a crucial mechanism of the resistance acquisition. Significant differences in frost resistance were detected within winter cultivars. The most resistant showed a behaviour similar to that of winter barley, suggesting that it should be possible to improve the resistance of winter oat to a level similar to that of winter barley. Rizza, F. Pagani, D. Cattivelli, C. Stanca, A.M. 2001. Plant Breeding 120: 389-396; Cattivelli, L. Crosatti, C. Rizza, F. 1995 Journal of Genetics & Breeding 49:333-338.vokMyynti MTT tietopalvelu
Genetic variability in yellow pigment components in cultivated and wild tetraploid wheats
No full textBeyond sustainability in food systems: Perspectives from agroecology and social innovation
No full textFood security faces many multifaceted challenges, with effects ranging far beyond the sectors of agriculture and food science and involving all the multiscale components of sustainability. This paper puts forward our point of view about more sustainable and responsible approaches to food production research underlying the importance of knowledge and social innovation in agroecological practices. Increased demand for food worldwide and the diversification of food choices would suggest the adoption of highly productive, but low-resilient and unsustainable food production models. However, new perspectives are possible. These include the revitalization and valorization of family-based traditional agriculture and the promotion of diversified farming systems as a social and economic basis to foster social-ecological conversion. Additionally, they encompass the forecasting of the Participatory Guarantee Systems (PGS) and the drafting of a new agenda for food sovereignty. Thanks to a desk analysis, the study describes and discusses these perspectives, their trajectories and action research implications. The results suggest the need to adopt a more inclusive and systemic approach to the described problems, as the solutions require the promotion of responsibility within decision makers, professionals and consumers. This appears essential for reading, analyzing and understanding the complex ecological-functional, social and economic relations that characterize farming systems, as well as mobilizing local communities
Hv-WRKY38: A New Transcription Factor Involved in Cold- and Drought-Response in Barley
No full textWRKY proteins constitute a large family of plant specific transcription factors implicated in many different processes. Here we describe Hv-WRKY38, a barley gene coding for a WRKY protein, whose expression is involved in cold and drought stress response. Hv-WRKY38 was early and transiently expressed duringexposure to low non-freezing temperature, in ABA-independent manner. Furthermore, it showed a continuous induction during dehydration and freezing treatments. A WRKY38:YFP fusion protein was found to localise into the nucleus upon introduction into epidermal onion cells. Bacterially expressed Hv-WRKY38 was able to bind in vitro to the W-box element (T)TGAC(C/T) also recognisable by other WRKY proteins. Hv-WRKY38 genomic DNA was sequenced and mapped onto the centromeric region ofthe barley chromosome 6H. Arabidopsis and rice sequences homologous to Hv-WRKY38 were also identified. Our results indicate that Hv-WRKY38 transcription factor may play a regulatory role in abiotic stress response
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