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Horizontal Line (horizontal + line)

Distribution by Scientific Domains

Medical Sciences	42%
Life Sciences	42%

Selected Abstracts

Fluid flow and heat transfer of natural convection at a slightly inclined, upward-facing, heated plate

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2002
Fumiyoshi Kimura
Abstract Natural convective flows over upward-facing, inclined plates were investigated experimentally, with an emphasis on the role of opposing flows that appear over the plates inclined slightly from the horizontal line. The flow fields over the plates and the surface temperatures of the heated plates were visualized with both dye and a liquid-crystal thermometry. The results showed that both the descending and ascending flows appeared over the plates when the inclination angles of the plates were less than 15°. The two flows collided with each other at a certain distance from the plate edge, and then detached from the plate to become a thermal plume. It was found that the above distance was determined solely by the inclination angles and was independent of sizes and heat fluxes of the plates. The local heat transfer coefficients of the plates were also measured. The results showed that the heat transfer from the plate was enhanced by the occurrence of the descending flows. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(5): 362,375, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10036 [source]

The effect of perceived length on visuomotor localization

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2001
Nick Fogt
Summary Purpose: The purpose of this experiment was to study visuomotor localization in the presence of either a horizontal array of equally spaced dots or a thin horizontal line. Methods: Pointing behavior was used to assess directional localization. In experiment 1, subjects were made myopic using a contact lens and then corrected with a spectacle lens. Subjects were tested in the presence and absence of a regularly spaced, horizontal array of dots with and without the contact lens/spectacle combination. In experiment 2, subjects wore the contact lens/spectacle in all cases. Some subjects were tested in the presence and then in the absence of a regularly spaced, horizontal array of dots while the order of conditions was reversed for other subjects. In experiments 3 and 4, subjects were tested without the contact lens/spectacle combination. In experiment 3, subjects were tested in the absence and then in the presence of a regularly spaced, horizontal arrays of dots. In experiment 4, subjects were tested in the absence and then in the presence of a thin horizontal line. Results: In experiment 1, in the absence of the array of dots, subjects undershot targets with the contact lens/spectacle combination. When the array was present, pointing with the contact lens/spectacle combination was accurate. In experiment 2, subjects undershot targets in the absence of the array of dots if this condition was performed first. If the array was present in the initial condition, the pointing undershoot in the second condition (array absent) was reduced. In all cases, the pointing undershoot was reduced in the presence of the array. In experiments 3 and 4, a pointing overshoot was found in the presence of an array of dots or a thin line. Conclusions: It is concluded that extraretinal eye position information is not the primary determinant of visuomotor localization in the presence of a horizontal contour. The overshoot produced by a horizontal contour may be related to a length illusion brought about by spatial filtering in the visual system or inaccurate distance judgments. [source]

Patterns of Innervation of the Anterior Maxilla: A Cadaver Study with Relevance to Canine Fossa Puncture of the Maxillary Sinus,

THE LARYNGOSCOPE, Issue 10 2005
Simon Robinson FRACS
Abstract Objectives/Hypothesis: Complications from canine fossa puncture of the maxillary sinus are caused by damage to the anterior superior alveolar nerve (ASAN) and the middle superior alveolar nerve (MSAN). The aim of this study was to elucidate the pattern of ASAN and MSAN within the anterior maxilla and to secondly determine suitable surgical landmarks to aid in accurately localizing the area of the canine fossa least likely to produce complications when a trocar is passed into the maxillary sinus. Methods: Anatomic dissection of the anterior face of the maxilla from 20 cadaver heads was performed. The pattern and presence of the ASAN and MSAN was identified on each side and tabulated. Landmarks for the safest entry point for canine fossa puncture were determined, and each side had a puncture placed using these landmarks. Any disruption of nerves was noted. Results: Multiple differing patterns of ASAN were identified. The ASAN emerged from its foramen as a single trunk in 30 (75%) sides and in a double trunk in 10 (25%). In 24 (60%), single or multiple branches from the ASAN trunks were identified. A MSAN was identified in 9 (23%) maxillae. The safest entry point for a canine fossa puncture was where a vertical line drawn through the mid-pupillary line was bisected by a horizontal line drawn through the floor of the pyriform aperture. Conclusions: There is significant variation in the pattern of ASAN and MSAN within the anterior face of the maxilla. By using the newly described landmarks when performing a canine fossa puncture, there is reduced risk of damage to these nerves and provides a reliable point to enter the maxillary sinus. [source]

Optimising tracheal intubation success rate using the Airtraq laryngoscope

ANAESTHESIA, Issue 3 2009
G. Dhonneur
Summary In this study we have used a video-recording, retrospective analysis technique to evaluate the influence of the AirtraqÔ laryngoscope manipulations and the resulting changes in position of the glottic opening and inter-arytenoids cleft, on the success rate of tracheal intubation. The video recordings of the internal views of 109 tracheal intubation attempts, in 50 anaesthetised patients were analysed. We demonstrated that successful tracheal intubation using the Airtraq laryngoscope require the glottic opening to be centred in the view, and positioning the inter-arytenoid cleft medially below the horizontal line in the centre of the view. We also demonstrated that repositioning of the Airtraq laryngoscope following a failed tracheal intubation attempt required the performance of a standard series of manoeuvres. [source]

Comparing the anatomical consistency of the posterior superior iliac spine to the iliac crest as reference landmarks for the lumbopelvic spine: A retrospective radiological study

CLINICAL ANATOMY, Issue 7 2007
J.M. McGaugh
Abstract A palpation reference line coursing between the superior-most aspect of the iliac crests has been reported to cross the L4 spinous process or L4/L5 intervertebral space in ,80% of the population. Comparable data have not been defined for the line coursing between the posterior superior iliac spines (PSIS). The purpose of this study was to compare the anatomical consistency of the PSIS to the iliac crest as landmarks used for spinal palpation. One hundred computerized tomographic images were reviewed in a three-dimensional setting. Two horizontal lines were constructed on each image: Line 1 representing the superior-most aspect of the iliac crest and Line 2 representing the inferior margin of the PSIS. The vertical distance between each horizontal line and the inferior edge of its respective spinous process were measured. The PSIS corresponded to the S2 spinous process in 81% of subjects and the iliac crest to the L4 spinous process in 59% of subjects. Distance measures suggest that the PSIS was closer to S2 versus the iliac crest to L4 (t = 6.998; P < 0.01). The PSIS crossed S2 more frequently than the iliac crest crossed L4 (,2 = 12.719, P , 0.01). The study findings support the relationship between the PSIS, and the spinous process of S2 is more consistent when compared to the iliac crest and the spinous process of L4. The PSIS reference line may be used to find S2 as a reference standard in validity and reliability palpation studies in the lower lumbar spine. Clin. Anat. 20:819,825, 2007. © 2007 Wiley-Liss, Inc. [source]

Reviving a neglected celestial underwater polarization compass for aquatic animals

BIOLOGICAL REVIEWS, Issue 1 2006
Talbot H. Waterman
ABSTRACT Substantial in situ measurements on clear days in a variety of marine environments at depths in the water down to 200 m have demonstrated the ubiquitous daytime presence of sun-related e-vector (= plane of polarization) patterns. In most lines of sight the e-vectors tilt from horizontal towards the sun at angles equal to the apparent underwater refracted zenith angle of the sun. A maximum tilt-angle of approximately 48.5°, is reached in horizontal lines of sight at 90° to the sun's bearing (the plane of incidence). This tilt limit is set by Snell's window, when the sun is on the horizon. The biological literature since the 1980s has been pervaded with assumptions that daytime aquatic e-vectors are mainly horizontal. This review attempts to set the record straight concerning the potential use of underwater e-vectors as a visual compass and to reopen the field to productive research on aquatic animals' orientation and navigation. [source]

Comparing the anatomical consistency of the posterior superior iliac spine to the iliac crest as reference landmarks for the lumbopelvic spine: A retrospective radiological study