1,720,977 research outputs found
How to model thick thermo-poro-elastic inclusions
Full text linkVolcanic regions can be characterised by different unrest phenomena and secondary volcanism. Several studies link these phenomena to both magma and hydrothermal fluids. For instance, in the case of the widely studied Campi Flegrei caldera, recent literature suggests that thermo-poro-elastic (TPE) inclusion models are suitable to describe both the observed deformation and seismicity that often accompany its unrest episodes. Some recent works propose analytical solutions to model the case of a thin disc-shaped inclusion, i.e. with a thickness much smaller than its radius. As this restriction may be critical, TPE inclusion models were subsequently extended to cylindrical-shaped inclusions, with an arbitrary thickness, by representing them as a superposition of several thin disc-shaped inclusions (elements). In this paper, we demonstrate how to estimate the minimum number of elements to represent both displacement and stress fields caused by cylindrical TPE inclusions with an arbitrary aspect-ratio (thickness over radius). For aspect ratios greater than 0.3, a single element model will no longer prove suitable to represent both displacement and stress with a good accuracy
Una cosmologia settecentesca tra filosofia e scienza: Ruggero Giuseppe Boscovich interlocutore di Newton e di Leibniz.
No full textIn his main scientific treatise, "Philosophiae naturalis theoria redacta ad unicam legem virium in natura existentium", R. G. Boscovich, a great Dalmatian mathematician, scientist and philosopher, appeals to Leibnizian monadological dynamism in order to overpass the limits of Newtonian mechanism and so he foresees some important developments of contemporary physics, substituting energy for matter, centres of force for atoms and giving rise to a radical transformation in the idea of atom
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
Hormone replacement therapy in perimenopause: effect of a low dose oral contraceptive preparation on bone quantitative ultrasound characteristics.
No full textOBJECTIVES:
Our aim was to assess the effects of a combined oral contraceptive (OC) preparation on bone quantitative ultrasound and biochemical markers of bone metabolism in perimenopausal women.
DESIGN:
Bone biochemical markers and bone quantitative ultrasound were evaluated in a longitudinal 2-year follow-up study conducted in healthy, normally menstruating perimenopausal women, perimenopausal oligomenorrheic women, and age-matched oral contraceptive-treated women (20 micrograms of ethinyl estradiol plus 0.15 mg desogestrel). The results were analyzed by factorial or repeated-measures analysis of variance, as appropriate.
RESULTS:
In normal women, there were no significant modifications in menstrual cycle, plasma FSH and estradiol levels, biochemical markers of bone turnover, and bone quantitative ultrasound. Conversely, in oligomenorrheic women, an increase in the cycle length with a concomitant rise in circulating plasma FSH and parallel decrease of plasma estradiol levels was evident. In this group, an increase in both urinary excretion of hydroxyproline and plasma osteocalcin levels paralleled a decrease in bone quantitative ultrasound. In perimenopausal OC-treated women, the pattern of osteocalcin and urinary excretion of hydroxyproline showed a slight decrease, whereas bone quantitative ultrasound did not show any significant modification.
CONCLUSION:
Perimenopausal OC administration can prevent the increase in bone turnover and the decrease in bone quantitative ultrasound that follow the perimenopausal impairment of ovarian function
Quantitative bone ultrasonometry in climacteric women
No full textQuantitative bone ultrasound (QUS) measurement is an emerging technique in the assessment of osteoporosis risk. In this study, bone mineral density (BMD) (mg/cm2) of lumbar vertebrae, neck, Ward's triangle and trochanter were measured by DXA and the phalanx amplitude dependent speed of sound (AD-SOS) was measured by QUS in climacteric (n = 1025) women. The relationship between AD-SOS and BMD values at different skeletal sites was significant, even if the analysis showed poor correlation coefficients. These data seem to indicate that QUS can detect bone characteristics in addition to density. The AD-SOS was higher in premenopausal than in perimenopausal women. The AD-SOS further decreases in postmenopausal women without hormone replacement. The age at menopause is relevant for predicting the AD-SOS in the postmenopausal years. Conversely, the maintenance of a regular menstrual function is associated with higher AD-SOS. Thus, the early impairment and cessation of ovarian function can lead to an earlier and/or sharper decline in bone homeostasis that can be detected by QUS. In conclusion, AD-SOS is a valuable index in detecting menopausal bone loss, and could be used for the patient follow-up during menopausal transition and in therapeutic trial
Longitudinal evaluation of perimenopausal femoral bone loss: effects of a low-dose oral contraceptive preparation on bone mineral density and metabolism.
No full textTo characterize the pattern of biochemical markers of bone metabolism and femoral bone mineral density in eumenorrheic and oligomenorrheic perimenopausal women, and assess the effects of a low-dose oral contraceptive (OC) on bone metabolism and femoral bone density, bone biochemical markers and femoral bone density (measured at the neck, Ward's triangle and trochanter regions) were evaluated in a longitudinal 2-year follow-up study. The study was conducted in healthy, normally menstruating perimenopausal women (n = 18), perimenopausal oligomenorrheic women (n = 18), and perimenopausal oligomenorrheic women treated with an OC containing 20 microg ethinylestradiol plus 0.15 mg desogestrel (n = 19). The results were analyzed by factorial or repeated measures analysis of variance, as appropriate. During the observation period, in normally menstruating women there were no changes in the menstrual cycle, plasma FSH and estradiol levels, biochemical markers of bone turnover or femoral bone density. In oligomenorrheic untreated women an increase in cycle length with a concomitant decrease in plasma estradiol and an increase in plasma FSH levels were found (p < 0.05). In this group a significant increase in urinary excretion of hydroxyproline and in plasma osteocalcin levels with a concomitant significant decrease in femoral bone density (p < 0.05) occurred. In OC-treated women, osteocalcin plasma levels and urinary excretion of hydroxyproline significantly (p < 0.05) decreased, leading to a significant (p < 0.05) increase in femoral bone density. It is concluded that perimenopausal OC administration can avoid the increase in bone turnover and the decrease in femoral bone density due to the perimenopausal impairment of ovarian function
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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