Principles of Operative Treatment
Louis Solomon, David Warwick, Selvadurai Nayagam in Apley and Solomon's Concise System of Orthopaedics and Trauma, 2014
Fixation is achieved in one of two ways: (a) puttylike methylmethacrylate cement is applied firmly to the exposed metaphyseal bone surface and the implant is then embedded in the cement and held there until the methylmethacrylate polymerizes and hardens; the cement acts as a grouting material which fills the spaces between the implant and the bone and penetrates into interstices on the bone surface; (b) the alternative method is to prepare the bone bed to a predetermined shape and size and then press-fit the implant snugly to the bone without cement. In neither case is there a true bond between implant and bone. Various modifications of implant design and surface coating have helped to reduce the long-term problem of implant loosening, but most important of all is sound technique.
Laparoscopic Ventral Hernia Repair
Jeff Garner, Dominic Slade in Manual of Complex Abdominal Wall Reconstruction, 2020
As with most other areas of surgery, ventral hernia repair has not been immune to the march of minimally invasive techniques designed to minimise tissue trauma and speed up recovery. The first series of laparoscopic ventral hernia repairs was reported by LeBlanc and Booth in 1993,2 in which a sheet of non-adherent PTFE material was sutured to the undersurface of the abdominal wall, simply covering or ‘bridging’ the ventral defect. Operative techniques have changed little since then and many of the controversial questions that inevitably arose remain unanswered: when is the laparoscopic approach indicated? What mesh should be used? Is a mesh needed every time? What mesh size? What fixation? Should the defect be closed? This chapter addresses each of these controversies, describes the ‘standard’ operative approach, some variations on this, and some pitfalls.
Smart Eye Tracking Sensors Based on Pixel-Level Image Processing Circuits
Iniewski Krzysztof in Integrated Microsystems, 2017
Fixation or visual fixation means maintaining the visual gaze on a location. Humans (and other animals with a fovea) typically alternate saccades and visual fixations. Visual fixation is never perfectly steady: this eye movement occurs involuntarily. The term “fixation” can also be used to refer to the point in time and space of the focus rather than to the act of fixating; a fixation in this sense is the point between any two saccades, during which the eyes are relatively stationary and virtually all visual input occurs. The fixation always lasts at least 100 ms. It is during these fixations that most visual information is acquired and processed. At least three types of small involuntary eye movements commonly occur during the fixations: Flicks are very rapid (perhaps as little as 30 ms apart), involuntary, saccade-like movements of less than 1°; drifts are very small and slow (about 0.1°/s), apparently random motions of the eye; and tremors are tiny (less than 30 arc seconds), high-frequency (30–150 Hz) eye vibrations [13].
Metaphors of pathology*
Published in International Review of Psychiatry, 2018
Giovanni Stanghellini
In Kretschmer’s doctrine the elements of the proportion are character traits (‘asthenic base’ and ‘sthenic spike’). In Binswanger (Cargnello, 1977), proportion takes quite a different form. For instance, fixation (Verstigenheit, sometimes also translated with ‘extravagance’)—an image Binswanger uses to describe certain forms of autistic existence—is a special kind of disproportion between horizontality and verticality. Fixation is a form of existential failure characterized by a kind of artificial and extreme going over the top. It is climbing much too high, lacking the necessary experience which would assure the capacity not to get lost in this scaling of the heights. For Binswanger, horizontality and verticality are not character traits, but rather existential categories, the concrete and metaphorical directions of human existence, which appear immediately in dreams, in artistic creations, as in spoken language.
Visual rehabilitation using microperimetric acoustic biofeedback training in individuals with central scotoma
Published in Clinical and Experimental Optometry, 2019
Dhanashree Ratra, Sarika Gopalakrishnan, Daleena Dalan, Vineet Ratra, Deepali Damkondwar, Gella Laxmi
Fixation stability was assessed and quantified in four ways. First, the percentage of fixation points falling within a circle of two degrees and four degrees from fixation were measured. Second, the fixation was qualified as ‘predominantly central fixation’ if > 50 per cent of fixation points were within the central circle. Eyes with > 25 per cent but < 50 per cent were labelled as ‘poor central fixation’. Eyes with < 25 per cent of fixation points in the central circle were classified as ‘predominantly eccentric fixation’. As per the protocol given by Fujii et al.,2002 the fixation was further classified as: ‘stable fixation’, when 75 per cent of fixation points fall within the central two degrees; ‘relatively unstable’, when 75 per cent of points are within the central four degrees; and ‘unstable’, when less than 75 per cent are within four degrees.
Mass spectrometry-based phospholipid imaging: methods and findings
Published in Expert Review of Proteomics, 2020
Al Mamun, Ariful Islam, Fumihiro Eto, Tomohito Sato, Tomoaki Kahyo, Mitsutoshi Setou
PLs imaging at the cellular level has been made possible by SIMS imaging as it offers the capability of resolving very small features which can be as low as a hundred nanometers. Sample for single-cell analysis includes the isolated cells from the specimen or cultured cell. Unfortunately, live cells cannot be analyzed directly in SIMS as it works under a high vacuum condition. Generally, cells are extracted or grown on an appropriate substrate such as silicon wafer or gold-coated silicon wafer [58] followed by fixation to minimize sample degradation. Two fixation methods are commonly applied: (i) chemical fixation using glutaraldehyde, and (ii) cryofixation. A cryofixation method, namely plunge fixation, has been shown to be advantageous for single-cell lipid imaging [59]. In plunge freezing, samples are stored in liquid nitrogen at −196°C after washing by a mixture of propane and isopentane (3:1). Interestingly, enhanced signal intensity for PLs has been reported when matrix solution is added on the cell surface prior to the fixation [58]. After fixation, frozen samples are freeze-dried and stored until analysis.
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