1,720,975 research outputs found
Room temperature direct bonding of LiNbO3 crystal layers and its application to high-voltage optical sensing
No full textLiNbO3 is a crystal widely used in photonics and acoustics, for example in electro-optic modulation, nonlinear optical frequency conversion, electric field sensing and surface acoustic wave filtering. It often needs to be combined with other materials and used in thin layers to achieve the adequate device performance. In this paper, we investigate direct bonding of LiNbO 3 crystals with other dielectric materials, such as Si and fused silica (SiO2), and we show that specific surface chemical cleaning, together with Ar or O2 plasma activation, can be used to increase the surface free energy and achieve effective bonding at room temperature. The resulting hybrid material bonding is very strong, making the dicing and grinding of LiNbO3 layers as thin as 15 νm possible. To demonstrate the application potentials of the proposed bonding technique, we have fabricated and characterized a high-voltage field sensor with high sensitivity in a domain inverted and bonded LiNbO3 waveguide substrate
Quantitative analysis of changes occurring in muscle vastus lateralis in patients with heart failure after low-intensity training.
No full textOBJECTIVE: To quantitate the changes occurring in muscle vastus lateralis after exercise training of low intensity adopted for the rehabilitation of patients with chronic heart failure.
STUDY DESIGN: Nine consecutive males with a clinical diagnosis of idiopathic dilated and ischemic cardiomyopathy underwent an eight-week period of training. The intensity of the work was calculated as 40% of peak VO2. The program consisted of 30 minutes of cycling three times per week. A cardiopulmonary exercise test, hemodynamic measurements and echocardiographic studies were carried out. Needle biopsies were taken from muscle vastus lateralis before starting and after completing training. Quantitative analysis was carried out on sections stained with ATPase at pH 9.5 for measurement of the lesser diameter of type 1 and 2 fibers (by using an image analyzer) and on UEA 1-stained sections for capillary density and capillary/fiber ratio (by using a frame in the eyepiece of the microscope). The Wilcoxon test was applied to identify significant differences before and after training. Spearman's rank correlation coefficient was also calculated to highlight any correlation between the morphologic data and results of clinical tests.
RESULTS: After completing the training program, all the patients experienced an improvement in exercise tolerance and a significant increase (P < .004) in the VO2 and VCO2 peak. Skeletal muscle showed a significant (P < .02) increase in the capillary/fiber ratio. The changes were not significantly correlated with any of the clinical findings.
CONCLUSION: Low-intensity training can improve the functional capacity of patients with heart failure while producing only mild morphologic changes in their muscles
L’USO FORZATO DELL’ARTO SUPERIORE PARETICO IN SOGGETTI CON ESITI DI TRAUMA CRANICO: STUDIO PILOTA.
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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
All-optical electric field sensor in domain inverted LiNbO3 for harsh environment
No full textOptical high-voltage sensors have outstanding advantages in terms of isolation and immunity to electromagnetic interference. So far, several configurations have been proposed, mostly based on integrated Mach-Zehnder interferometers [1] or polarization/phase rotation in piezo-electric crystal [2]. While the first scheme requires initial electrical bias to compensate for the phase mismatch between the two arms, the second one requires interrogation or phase noise reduction systems that are expensive to implement. Near cut-off optical waveguide devices have been already reported in LiNbO3. In particular, the use of waveguides at cut-off was proposed for modulation in the field of optical communications [3,4] and sensing [5]. We present a novel integrated optical high voltage sensor based on a Z-cut LiNbO3 which operates without any metallic parts. The proposed device is sketched in Fig. 1 (left). An annealed proton exchange (APE) waveguide near cut-off is fabricated in Z-cut LiNbO3 and centered in a domain inverted region. The application of an external electric field parallel to the z axis of the device produces a refractive index change n between positive and negative domains given by ne 3r33E, where E is the intensity of the external electric field along the z-axis, ne=2.14 and r 33=30.8 pm/V are the refractive index and the electro-optic coefficient along the z-axis, respectively. As a consequence the optical mode will broaden so that, after a sufficient propagation length, a loss is produced due to a mode-profile mismatch of the guided modes between active and passive regions
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
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