1,721,022 research outputs found
Paving the way for the next generation Cultural Digital Library Services: the case study of ‘Fortuna visiva of Pompeii’ within the BRICKS project
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Markov abstractions for PAC reinforcement learning in non-Markov decision processes
Full text linkOur work aims at developing reinforcement learning algorithms that do not rely on the Markov assumption. We consider the class of Non-Markov Decision Processes where histories can be abstracted into a finite set of states while preserving the dynamics. We call it a Markov abstraction since it induces a Markov Decision Process over a set of states that encode the non-Markov dynamics. This phenomenon underlies the recently introduced Regular Decision Processes (as well as POMDPs where only a finite number of belief states is reachable). In all such kinds of decision process, an agent that uses a Markov abstraction can rely on the Markov property to achieve optimal behaviour. We show that Markov abstractions can be learned during reinforcement learning. Our approach combines automata learning and classic reinforcement learning. For these two tasks, standard algorithms can be employed. We show that our approach has PAC guarantees when the employed algorithms have PAC guarantees, and we also provide an experimental evaluation
3D GPU-based implementation of the contrast source inversion for breast lesion detection
Full text linkIn microwave tomography, applying a proper inversion method to the measured data may result in quantitative imaging of the electrical properties (EPs) at the frequencies of the used electromagnetic radiation. Some physiopathological statuses of the breast tissue can be distinguished based on the estimated EPs [1]. A previous approach presented in [2] reports preliminary results obtained with a two-dimensional implementation of the Contrast Source Inversion (CSI) method [3] applied to simulated data. This work aims to discuss the transition to a 3D algorithm. Some optimization techniques in the MATLAB environment have been applied to the 2D version to reduce time consumption, which becomes a predominant variable with 3D data. Namely, computationally expensive operations on large data have been transferred to GPU (NVIDIA A 100 80 GB). This leads to an advantage especially for the FFT, which is performed in every iterative step. The efforts have permitted to reduce the execution time of each iterative step, reaching a speed-up factor of about 25 with respect to the CPU (Intel Xeon Gold 6430 2.10 GHz 512 GB RAM) version of the code. To obtain preliminary results about the feasibility of the 3D imaging method for detecting dielectric properties, a virtual experiment was performed. The transmit-receive setup is composed of a transmitting antenna that assumes ten equidistant positions around a cylindrical phantom, and a receiving antenna assuming forty equidistant positions around it. A heterogeneous phantom was considered, with electrical properties that emulate the ones of a healthy breast (σ = 0.1 and εr = 4), and a longitudinal cylindrical inclusion (r = 1 cm), whose high electrical properties simulate those of a breast lesion (σ = 1 and εr = 15). The incident electric field was obtained through the simulation of a Hom antenna fed at the frequency of 5 GHz, performed in Sim4Life. Total electric fields were computed in the receiving antennas’ locations and a homogeneous initial guess (σ = 0.01 and εr = 3) was adopted. An additive regularization in the CSI cost functional was introduced to overcome the image artifacts induced by the ill-posedness of the inverse scattering problem. Figure 1 provides results obtained after 3,000 iterations of CSI (about 2.5 hours of execution)
Synthetic scaffolds: lights and shadows
No full textDefects of the skeletal system are an impediment to the normal function of the human organism. Problems still arise concerning the optimal therapy of bony defects after trauma or tumor resection. Today, biomaterials may be designed with the aim that once implanted they will help the body to heal itself. In particular, temporary matrices named scaffold with tailored morphological and functional properties may provide a specific environment and architecture able to promote the bone in-growth. Current work proposes a critical assessment of the most famous and recently used scaffold preparation strategies to emboss lights and shadows of the current bone regeneration in comparison with traditional approaches based on the tissue substitution
Automata Cascades: Expressivity and Sample Complexity
Full text linkEvery automaton can be decomposed into a cascade of basic prime automata. This is the Prime Decomposition Theorem by Krohn and Rhodes. Guided by this theory, we propose automata cascades as a structured, modular, way to describe automata as complex systems made of many components, each implementing a specific functionality. Any automaton can serve as a component; using specific components allows for a fine-grained control of the expressivity of the resulting class of automata; using prime automata as components implies specific expressivity guarantees. Moreover, specifying automata as cascades allows for describing the sample complexity of automata in terms of their components. We show that the sample complexity is linear in the number of components and the maximum complexity of a single component, modulo logarithmic factors. This opens to the possibility of learning automata representing large dynamical systems consisting of many parts interacting with each other. It is in sharp contrast with the established understanding of the sample complexity of automata, described in terms of the overall number of states and input letters, which implies that it is only possible to learn automata where the number of states is linear in the amount of data available. Instead our results show that one can learn automata with a number of states that is exponential in the amount of data available
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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