Does soccer cleat design influence the rotational interaction with the playing surface?     

Fabio Galbusera  Davide Zai Tornese  Federica Anasetti  Simone Bersini  Piero Volpi  Luigi La Barbera 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):293-301

Non-contact injuries in soccer players may be related to the interplay between cleat type and playing surface, and bladed shoes were often blamed for non-contact injuries with no research support. The aim of this study was to compare the rotational resistance (stiffness and peak sustainable torque) among three types of soccer cleats (metal studs, molded rubber studs, and bladed) in a controlled laboratory environment. The shoes were tested on both natural and artificial turfs under a compressive preload of 1000 N and with internal and external rotations. The three shoe models showed comparable performances with a good repeatability for each individual test on both playing surfaces. A less stiff behavior was observed for the natural turf. A tendency toward highest peak torque was observed in the studded model on natural surface. The bladed cleats provided peak torque and rotational stiffness comparable to the other models. Studded and bladed cleats did not significantly differ in their interaction with the playing surface. Therefore, soccer shoes with bladed cleats should not be banned in the context of presumed higher risk for non-contact injuries.  相似文献   

Multispectral data cube acquisition of aligned images for document analysis by means of a filter-wheel camera provided with focus control     

Gianfranco Bianco  Fabio Bruno  Maurizio Muzzupappa 《Journal of Cultural Heritage》2013,14(3):190-200

Multispectral imaging techniques are widely used to analyse and restore digital images of ancient documents degraded over time. In particular, acquisitions in infrared and ultraviolet bands can reveal information invisible by naked eye, which is not captured by conventional RGB imaging. Multispectral acquisitions are usually performed with filter-wheel cameras that mount a series of interference filters in front of the sensor to select the spectral band in which the document has to be acquired. Due to the use of different filters, the focus of the lens changes and it is necessary to adjust it manually for each filter, because such imaging systems are devoid of automatic focusing. Thus the acquired images may not be perfectly in-focus and have misalignments. In this work we present an automatic solution to acquire a multispectral data cube of aligned images that can be used in document analysis to extract and/or separate information through enhancement techniques. A custom-made motorized autofocus system controlled by software has been installed on a filter-wheel camera, which allows us to acquire in-focus images automatically at each filter changing, and a registration method based on Fourier-Mellin transform aligns these images. A preliminary calibration is performed to set the focusing of each filter with the working distance. As a result, the camera can capture images independently from the contrast of the scene, also in presence of documents with homogeneous texture. The proposed solution reduces considerably the acquisition time and offers a tool to acquire automatically the data cube to be used in further image analysis techniques. The results of experimentations are hereby presented and discussed.  相似文献   

The Contribution of Openness to Transforming Education     

Fabio Nascimbeni 《European Journal of Education》2015,50(4):400-403

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Venture capital financing and the growth of high-tech start-ups: Disentangling treatment from selection effects   总被引：3，自引：0，他引：3  

Fabio Bertoni  Massimo G. ColomboLuca Grilli 《Research Policy》2011,40(7):1028-1043

The financial and innovation literature generally claims that venture capital (VC) investments spur the growth of new technology-based firms (NTBFs). However, it has proved difficult so far to separate the “treatment” effect of the VC investment from the “selection” effect attributable to the ability of the VC investor to screen high growth NTBFs. The aim of this work is to test whether VC investments have a positive treatment effect on the growth of employment and sales of NTBFs. For this purpose we consider a 10-year longitudinal data set for 538 Italian NTBFs, most of which are privately held. The sample includes both VC-backed and non-VC-backed firms. We estimate Gibrat-law-type dynamic panel-data models augmented with time-varying variables that capture the VC status of firms. To control for the endogeneity of VC investments we use several GMM estimators. The econometric results strongly support the view that VC investments positively influence firm growth. The treatment effect of VC investments is of large economic magnitude, especially on growth of employment. Most of it is obtained immediately after the first round of VC finance. Conversely, the selection effect of VC appears to be negligible in the Italian context.  相似文献   

A multi-collection latent topic model for federated search     

Mark Baillie  Mark Carman  Fabio Crestani 《Information Retrieval》2011,14(4):390-412

Collection selection is a crucial function, central to the effectiveness and efficiency of a federated information retrieval system. A variety of solutions have been proposed for collection selection adapting proven techniques used in centralised retrieval. This paper defines a new approach to collection selection that models the topical distribution in each collection. We describe an extended version of latent Dirichlet allocation that uses a hierarchical hyperprior to enable the different topical distributions found in each collection to be modelled. Under the model, resources are ranked based on the topical relationship between query and collection. By modelling collections in a low dimensional topic space, we can implicitly smooth their term-based characterisation with appropriate terms from topically related samples, thereby dealing with the problem of missing vocabulary within the samples. An important advantage of adopting this hierarchical model over current approaches is that the model generalises well to unseen documents given small samples of each collection. The latent structure of each collection can therefore be estimated well despite imperfect information for each collection such as sampled documents obtained through query-based sampling. Experiments demonstrate that this new, fully integrated topical model is more robust than current state of the art collection selection algorithms.  相似文献   

Modelling the joint torques and loadings during squatting at the Smith machine     

Biscarini A  Benvenuti P  Botti F  Mastrandrea F  Zanuso S 《Journal of sports sciences》2011,29(5):457-469

An analytical biomechanical model was developed to establish the relevant properties of the Smith squat exercise, and the main differences from the free barbell squat. The Smith squat may be largely patterned to modulate the distributions of muscle activities and joint loadings. For a given value of the included knee angle (θ(knee)), bending the trunk forward, moving the feet forward in front of the knees, and displacing the weight distribution towards the forefoot emphasizes hip and lumbosacral torques, while also reducing knee torque and compressive tibiofemoral and patellofemoral forces (and vice versa). The tibiofemoral shear force φ(t) displays more complex trends that strongly depend on θ(knee). Notably, for 180° ≥ θ(knee) ≥ 130°, φ(t) and cruciate ligament strain forces can be suppressed by selecting proper pairs of ankle and hip angles. Loading of the posterior cruciate ligament increases (decreases) in the range 180° ≥ θ(knee) ≥ 150° (θ(knee) ≤ 130°) with knee extension, bending the trunk forward, and moving the feet forward in front of the knees. In the range 150° > θ(knee) > 130°, the behaviour changes depending on the foot weight distribution. The conditions for the development of anterior cruciate ligament strain forces are explained. This work enables careful use of the Smith squat in strengthening and rehabilitation programmes.  相似文献   

Energy: Learning from the Past     

Fabio Bevilacqua 《Science & Education》2014,23(6):1231-1243

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A taxonomy of computer media in distance education     

Fabio Chacón 《Open Learning》2013,28(1):12-27

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A hermeneutic defence of the cognitive autonomy of science     

Fabio Gironi 《Metascience》2013,22(2):461-464

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Immigrant background and gender differences in primary students' motivations toward studying     

Fabio Alivernini  Elisa Cavicchiolo  Laura Girelli  Valeria Biasi  Fabio Lucidi 《The Journal of educational research》2018,111(5):603-611

In the study, based on a representative sample of 26,670 Italian fifth-grade students, the authors examine the academic motivational profiles of immigrant and native students, as well as of boys and girls. To reliably estimate mean differences, the measurement invariance of a short version of the Academic Self-Regulation Questionnaire was first established across the groups. Boys reported less autonomous motives for studying than girls while first-generation immigrant pupils showed higher levels of intrinsic motivation, identified regulation, and external regulation for studying than natives did. Also, second-generation immigrants had higher levels of academic motivation than natives did, although they were less motivated and reported less autonomous reasons for studying than first generations. While confirming the immigrant paradox in a country with a rapidly increasing level of immigrant students, findings show that second-generation immigrants not only report a lower quantity of motivation than first-generations, but also appear to have a different quality of motivation.  相似文献