1,721,078 research outputs found
Piezosurgery in the excision of middle ear tumors: effects on mineralized and non mineralized tissues
No full textBACKGROUND:
Piezosurgery is a new instrument able to cut bone without necrosis and non-mineralized tissue damage. The aim of this study was to test the Piezosurgery as a new and alternative method for the excision of middle-ear tumors and to analyze its effects on soft tissues.
MATERIAL/METHODS:
The Piezosurgery device was used to excise eight glomus tympanicum tumors and two primary B-cell lymphomas of the middle ear. The piezoelectric device uses low-frequency ultrasonic waves (24.7-29.5 kHz); the applied power can be modulated between 2.8 and 16 W and is programmed in accordance to the density of the bone. The equipment consists of two hand-pieces, two inserts, and two peristaltic pumps. The microvibrations that are created in the piezoelectric hand-piece cause the inserts to vibrate linearly by between 60 and 210 microm.
RESULTS:
Piezosurgery provided excellent control in all the patients, without bleeding and harmful effects on the adjacent structures of the middle and inner ear.
CONCLUSIONS:
Piezosurgery is a new and revolutionary osteotomy technique utilizing the microvibrations of scalpels at ultrasonic frequency, so that soft tissue will not be damaged even upon accidental contact with the cutting tip. The vibration frequency of Piezosurgery is optimal for mineralized tissue and does not cut the adjacent soft tissue, minimizing the risk of harming the adjacent tissues. This renders the piezoelectric device ideal for application at the border between hard and soft tissues as in the excision of a middle-ear tumor
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
Clinical evaluation of piezoelectric ear surgery
No full textAbstract
We evaluated the use of piezoelectric surgery (Piezosurgery;
Mectron Medical Technology; Carasco, Genoa, Italy) as a
means of avoiding some complications of osteotomy and
osteoplasty in otologic surgery, particularly in classic canalwall-
up mastoidectomy. Piezoelectric surgery is a recently
developed system for cutting bone with microvibrations
created by the piezoelectric effect. This effect occurs when
an electric current is passed through certain ceramics and
crystals, causing them to oscillate at ultrasonic frequencies.
OUT study population was made up of 20 adults with
unilateral chronic otitis media. In all patients, piezoelectric
surgery allowed for effective, precise, safe, easy, and rapid
intraoperative management. Inparticular, the instrument's
precision allowed surgeonsto make exact, clean, and smooth
cuts without causing any injury to adjacent soft tissue. No
complications were noted. We conclude that the piezoelectric
device is superior to conventionally rotating instruments
for performing classic canal-wall-up mastoidectomy
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
Binocular flash-induced nystagmus in humans
No full textObjective: The aim of this study was to demonstrate that binocular flash-induced nystagmus (B-FIN) can be evoked in humans. Design: The study evaluated the presence of B-FIN by stimulation with a stroboscopic flash. Setting: The study was conducted with 12 healthy patients in the Otorhinolaryngology Department of the University of Genoa (Italy), between April 2008 and January 2009. Methods: Patients underwent binocular flashing light stimulation, in the dark, by stroboscopic flash presented through a photostimulator at frequencies of 4.7 and 7.69 cycles/second for 120 seconds, with their eyes covered by a homogeneous field hollow opal hemisphere. The photostimulator was placed in three different positions with respect to the anterior-posterior axis: 0u, 45u to the right, and 45u to the left. Main Outcome Measures: Eyemovementswere recorded by electronystagmography (ENG). ENGrecording started 30 seconds before the stimulation and stopped 60 seconds after the end of the luminance stimuli to test the presence of flash induced after nystagmus (FIAN). Results: B-FIN was clearly evoked from 10 of the 12 healthy adults, whereas FIAN was evoked from 4 of the 12 subjects. The best stimulation of B-FIN was obtained through an intermittent luminance stimulus presented at a frequency of 4.7 cycles/second and the photostimulator placed at 0u to the optic axis. Conclusions: Our investigation demonstrates that B-FIN can be evoked in humans and its possible value in the differential diagnosis between central and peripheral vertigo
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
Piezosurgery® for removal of symptomatic ear osteoma
No full textPiezosurgery® is an ultrasound instrument (24.7-29.5 kHz) that is able to cut the bone without necrosis and nonmineralized tissue damage. The aim of this work has been to determine the applicability and efficiency of the piezoelectric device in the excision of symptomatic ear osteomas. 10 patients affected by osteoma of the external auditory canal (EAC) (6 right, 4 left) were enrolled. Patients underwent excision of the EAC osteoma through a transcanal approach, with the piezoelectric device. Before and 6 months after surgery, all the patients underwent pure-tone audiometry, tympanometry, transient-evoked otoacoustic emissions, distortion product otoacoustic emissions, auditory brainstem response, and electronystamographic recording. The piezoelectric device provided excellent control without side effects on the adjacent structures of the external, middle and inner ear. The piezoelectric device is a new bony scalpel using the microvibrations at ultrasonic frequency so that soft tissue (nerve, vessel, dura mater, skin, etc.) will not be damaged even on accidental contact with the cutting tip. A feature of the piezoelectric device is its good manageability, which makes it easy for a well-trained otologic surgeon to create a straight osteotomy line: this renders the piezoelectric device suitable for bone surgery and for removal osteomas of the EAC
Image-to-Geometry Registration: a Mutual Information Method exploiting Illumination-related Geometric Properties
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