1,720,974 research outputs found
Interaction between a regenerative matrix and wound bed in nonhealing ulcers: Results with 16 cases
Full text linkA chronic wound is a wound that is delayed in one of the wound-healing stages and cannot progress any further. A chronic wound leaves the patient at risk of infection and hospitalization. In these case series, 16 patients affected by venous ulcers underwent Hyalomatrix PA grafting for reconstructive surgery. Hyalomatrix PA is a bilayered, sterile, flexible, and conformable three-dimensional matrix made of fibers of HYAFF, a benzyl ester of hyaluronic acid, and a semipermeable silicone membrane. Hyalomatrix PA acts as a substitutive and regenerative permanent matrix able to replace the dermis providing a three-dimensional matrix for cellular invasion and capillary growth. The silicon layer controls water vapor loss avoiding an excessive loss of fluids and acts as a semipermeable barrier to the external agents. In the presented cases, the average area grafted per procedure was 153 cm(2). The length of followup ranged from 0.5 to 1 year. The final results were considered to be good in 12 cases, fair in 3 cases, and poor in one case. This study suggests that the combination of wound bed preparation with application of the hyaluronic regenerative matrix can be a valid approach for treatment of partial thickness ulcers
Insight in thermal and fluid-dynamic properties of ribbed ducts by means of a novel clustering method
Full text linkThe analysis of experimental results on heat transfer by forced convection in diverse ribbed ducts showed that different geometries lead to comparable thermal and fluid-dynamic performances. Moreover, no evident layout has been observed in data, and therefore a statistical clustering analysis is performed to detect the rationale, if any, underlying experimental results. A novel, ad-hoc developed technique is used to disengage the clustering from the data scaling and to account for the measurement uncertainty, consisting of an agglomerative procedure, based on the definition of dynamically-changing bounding boxes, whose size depends on the Nusselt number and the pumping power. Additional informations, such as the the relevance of the diverse geometric parameters and the persistence of similarity among configurations over a range of operating conditions, can be retrieved by means of the developed technique. The described method is applied to a large dataset, obtained during an experimental campaign carried on at ThermALab of Politecnico di Milano, aimed at identifying the Nusselt number and the friction factor for diverse-rib configurations in a large-aspect ratio channel with low-Reynolds flows. The considerations originated from of the results of the clustering analysis suggest the existence of an underlying structure, pointing to a possible unique parameter, termed "generalized blockage", which is possibly able to describe the global effect of the ribs geometry on forced convection
Numerical Simulations of the flow field within a 1:10 Aspect Ratio duct at intermediate Re
Full text linkNumerical simulations are carried on to study the fluid-dynamical features of a smooth duct with aspect ratio of 10. The duct is operated with an incompressible, newtonian fluid, whose Reynolds number, computed over the hydraulic diameter and bulk velocity, ranges from 470 to 14500, encompassing laminar and turbulent flow. To capture the details of all the flow scales, Direct Numerical Simulations are performed, by means of a code developed at Politecnico di Milano. The adopted code is a finite-difference, structured grid solver, that includes a mass flow rate correction. The latter guarantees high accuracy in the calculation of unsteady flows, or during the transition to turbulent regime, and it allows to check the consistency of numerical results. Both global parameters -including the friction factor and the identification of the laminar-to-turbulent transition and local flow features, e.g., corner vortexes, are investigated and presented in this work. Preliminary analyses agree fairly well with literature data and with experimental results obtained at ThermALab of Politecnico di Milano. The final goal of this work, including a deep integration between the numerical and the experimental setup, is to carry on detailed investigations of the fluid-dynamical and thermal characteristics of ribbed ducts, in the perspective of heat transfer enhancement and pressure drop reduction
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
Infrared image processing for local convective heat transfer measurements in rib-enhanced channels
Full text linkIn the context of an experimental study designed to retrieve the local heat transfer characteristics in closed channels with ribs in several configurations by IR thermography, a filtering strategy must be adopted to calculate the laplacian of the temperature field, to remove not only Gaussian noise, but also unwanted local features due to the pattern of the conductors of the heater. In this paper, these issues are addressed with a comparative analysis on filtering and interpolation techniques, in particular mean filtering, local surface fitting and cubic smoothing splines, which are carried out by showing their influence on the smoothed thermogram and on the laplacian of the temperature field. The use of cubic smoothing splines gives the best approximation of the temperature field with respect to the mean filter, which alters the temperature field in proximity of the ribs, and to surface interpolation. However, the only filter among those tried that gives meaningful derivatives on the whole image is the mean filter, with a kernel size equal or bigger to that of the spatial feature to be filtered. The resulting derivative also need further filtering to reduce local spikes induced by the filtering operations
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
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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