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151.
Kevin J. Boudreau Lars Bo Jeppesen Toke Reichstein Francesco Rullani 《Research Policy》2021,50(7):104264
The bulk of today's (“preorder-,” “reward-,” “gift-,” and “donation-based”) crowdfunding raises funds for small, private entrepreneurial ventures without granting funders private claims to the projects’ income or the ability to guarantee the realization and delivery of project outcomes. We theorize and show empirically – via a mixed-method approach applied to a representative and remarkably informative case – that the payoff structure for crowdfunders, akin to a public good contribution problem, leads to the tangible value of main project outputs exerting little influence on contributions to crowdfunding. This then raises the question of which funder motivations fund seekers may have to address to crowdfund their projects. We demonstrate the especially large role of non-pecuniary motivations and pinpoint three particular motivations that profit-seeking entrepreneurs may stimulate to be financed through crowdfunding. The findings hold important implications for entrepreneurs’ crowdfunding strategies, platform design, and our understanding of how this funding institution works in general. The study also adds to emerging research on the implications of the public good nature of crowdfunding. 相似文献
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153.
Alessandro Russo 《Inter-Asia Cultural Studies》2013,14(4):673-682
Abstract In the Chinese Cultural Revolution – the epicenter of the last great political sequence at worldwide level in the 1960s and 1970s – the flashing of unprecedented possibilities of post‐party politics was entangled with the epochal closure of a network of political culture. The Cultural Revolution proves to be extremely refractory to historical investigation because it undoes the established conceptual bridges between history and politics, bridges that all other social sciences crossed for studying politics. Therefore, new theoretical perspectives and new protocols of investigation are required, and not only for those events, but in the last analysis for the study of all political situations. The author discusses three main points for finding a new perspective. First, a basic distinction should be stressed between the intermittent nature of politics – one of the rarest modes of subjectivity, which exist only in singular intellectually inventive sequences – and the structural invariance of the state, despite the incessant historical mutations of its particular forms. Moreover, the relationships between the present state of depoliticization and the previous political situations deserve close analysis. The hypothesis is that the concrete form of the state in a given moment is the hollow imprint of the last great political sequence, or that it is shaped by a reactive de‐politicization. Finally, the declarations and the related behaviors of the actors during the events are the major analytical elements in the study of politics. However, the Cultural Revolution was marked to an unprecedented degree by increasing dissonances and, finally, irremediable ruptures between the processes created by the subjective declarations and the same network of political culture within which they were formulated. 相似文献
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155.
Alessandro Piras Milena Raffi Monica Perazzolo Ivan Malagoli Lanzoni Salvatore Squatrito 《Journal of sports sciences》2019,37(9):980-987
Microsaccades are important fixation eye movements for visual scene perception. Compared to novices, athletes make fewer fixations of longer duration toward limited interest areas crucial for action prediction. Thus, our aim was to study the microsaccade features during those fixations. Gaze behaviour of expert and novice table tennis players was recorder during a task in which subjects were instructed to predict the direction of the ball after the opponent’s throw. Three interest areas from the opponent’s body and one from the ball trajectory were identified. We analysed correctness of predictions, fixations, microsaccades and saccades to estimate the relationship between eye movements toward interest areas and success in the task. Compared to novices, experts fixated more on hand-racket during forehand and on trunk during backhand drive technique. Longer fixations on hand-racket and trunk were associated with higher microsaccade rate with a narrower directional distribution of them. It probably means that athletes focused their gaze on these small areas, suggesting enhanced attention mainly to them, and fewer consideration for the surrounding regions. We can assume that microsaccade rate and average direction could be related to the salience of interest areas during performance. 相似文献
156.
Martin Kokholm Fleron Niels Christian Hauerbach Ubbesen Francesco Battistella David Leandro Dejtiar 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(4):366-377
Motion capture through inertial sensors is becoming popular, but its accuracy to describe kinematics during changes in walking speed is unknown. The aim of this study was to determine the accuracy of trunk speed extracted using an inertial motion system compared to a gold standard optical motion system, during steady walking and stationary periods. Eleven participants walked on pre-established paths marked on the floor. Between each lap, a 1-second stationary transition period at the initial position was included prior to the next lap. Resultant trunk speed during the walking and transition periods were extracted from an inertial (240 Hz sampling rate) and an optical system (120 Hz sampling rate) to calculate the agreement (Pearson’s correlation coefficient) and relative root mean square errors between both systems. The agreement for the resultant trunk speed between the inertial system and the optical system was strong (0.67 < r ≤ 0.9) for both walking and transition periods. Moreover, relative root mean square error during the transition periods was greater in comparison to the walking periods (>40% across all paths). It was concluded that trunk speed extracted from inertial systems have fair accuracy during walking, but the accuracy was reduced in the transition periods. 相似文献
157.
Nasser Abu Zeid Marco Balducci Francesco Bartocci Roberto Regni Giovanni Santarato 《Journal of Cultural Heritage》2010,11(2):220-227
The electrical resistivity tomography (ERT) represents one of the widely used geophysical techniques for the exploration of the subsurface. In the last few years, this method has been demonstrated to be an efficient reconnaissance tool not only for monitoring degradation status of walls and foundations of historical buildings, but also for imaging the spatial distribution of injected mortar, commonly employed for consolidation purposes. A 3D resistivity tomography survey was carried out on four selected wall portions of the historical church of Montepetriolo, Perugia, Central Italy. The obtained 3D resistivity distribution models before and after grouting provided suggestive images of the internal structure of the studied walls. Moreover, the spatial distribution of the zones being filled with mortar was determined quantitatively by scaling the post- to the preinjection resistivity values. Using a well known correlation between resistivity and porosity, established in the geophysical community, a further step towards a more quantitative assessment was attempted to indirectly determine the unit volumes of the injected mortar The obtained results were satisfactory and in some cases almost similar to the yard data. Furthermore, two flat-jack tests confirmed the local increment of the mechanical resistance of the studied left front (2) and right lateral (3) wall portions. 相似文献
158.
Megan Foulkes Francesco Sella Theresa Elise Wege Camilla Gilmore 《Mind, Brain, and Education》2023,17(3):185-196
There is mixed evidence as to whether concrete manipulatives (e.g., toy animals) are better than abstract manipulatives (e.g., counters) for teaching mathematical concepts to children. Concreteness is defined as the amount of extraneous information a manipulative provides, and in this study we aimed to unpick which dimensions of concreteness influence manipulative choice. Researchers, teachers, and parents completed a comparative judgment task comparing images of manipulatives varying in different dimensions of concreteness, selecting which they would choose to teach arithmetic to children. The findings indicated homogeneous, 3-dimensional manipulatives were the most preferred across all groups to teach arithmetic to children, regardless of more extraneous features. This contradicts research recommendations to minimize the use of concrete manipulatives due to their distractive qualities. Instead, it suggests that some concrete features may be preferred in more naturalistic contexts. More research is required to investigate how different dimensions of concreteness influence learning outcomes for children both in artificial research contexts and in practice. 相似文献
159.
160.
Sara Bianchin Monica Favaro Pietro Alessandro Vigato Guido Botticelli Gioia Germani Silvia Botticelli 《Journal of Cultural Heritage》2009,10(3):379-387
The scientific approach to the restoration and monitoring of mural paintings, at S. Girolamo Chapel – SS. Annunziata Church in Florence, is reported as a fruitful example of the synergic collaboration between restorers and scientists in the planning and development of conservative interventions. Before restoration, the painting technique and the state of preservation of the pictorial cycle have been investigated firstly by close examination of the painted surfaces and then by optical and/or SEM-EDS microscopy and μFT-IR spectroscopy on appropriately selected samples. In particular, the original constituent materials and those belonging to subsequent restorations were characterized together with those originating from decay processes. In this mural painting cycle, a peculiar “fresco” technique has been used although an auxiliary binder for pigment distemper has been also employed. The use of this technique, sometimes in an improper way together with uncorrected restoration interventions, are the main responsible of the unsatisfactory state of conservation of many painted areas. Preliminary conservation trials and scientific studies were carried out to design the most convenient restoration intervention and to verify the correctness and non-invasive of the necessary operations. Special attention was devoted to cleaning procedures, continuously monitored by a physico-chemical methodology, mainly based on microinvasive, microscopic and spectroscopic investigations, to evaluate the efficiency, advantages and drawbacks of the proposed cleaning procedures and define the most appropriate ones. Finally, specific decay markers have been recognized, by a comparison of the results obtained from the detached samples with those deriving from artificially aged models, to be used for a correct future monitoring and maintenance of the wall paintings. 相似文献