12,184 research outputs found
Evaporation in fen wetlands
Full text linkWicken Fen represents a remnant of the once extensive peat fenlands of East Anglia, which survived large-scale drainage efforts intended to bring land into agricultural production due to its importance within the local economy and subsequently as a site of interest to scientists. Wicken Fen is managed so as to conserve a variety of habitats lost as a result of drainage and therefore does not represent a truly natural environment. Traditional management practices on Sedge Fen, the largest part of Wicken Fen, involve maintaining a 3 – 4 year harvesting cycle and controlling soil water levels. Previous hydrological studies of Wicken Fen have determined that soil water levels are strongly influenced by precipitation and evapotranspiration. The evaporative flux at Sedge Fen is commonly estimated by using meteorological data within empirical formulae such as the Penman Monteith equation owing to measurement difficulties. Furthermore, there has been little investigation of the evaporative loss from fens within the UK. This study aims to investigate the evaporative loss from Sedge Fen so as to better inform hydrological management and to describe evapotranspiration estimation techniques which may be employed at other fen sites. Eddy covariance measurements demonstrated that evapotranspiration from Sedge Fen was typically less than reference evapotranspiration estimates. Evapotranspiration estimates may be improved by consideration of surface parameters which can be described using meteorological data. Meteorological differences existed between Sedge Fen and the surrounding area, resulting in differing evapotranspiration estimates depending on where data was collected. Evapotranspiration measurements were used within a simple water budget model of Sedge Fen and demonstrated the lateral movement of soil water, a hydrological flux previously assumed to be of little consequence within the hydrological balance of Sedge Fen
Comparison of Ranges of Cervical Motion Measured by Gravity-Based Goniometry and Ultrasound-Based Motion Analysis System
No full textThe Effect of Transcutaneous Electric Nerve Stimulation on Somatosensory Evoked Potentials and Subjective Pain
No full textSpatial Organization of Premotor Neurons Related to Vertical Upward and Downward Saccadic Eye Movements in the Rostral Interstitial Nucleus of the Medial Longitudinal Fasciculus (Rimlf) in the Cat
No full text The rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) contains premotor-neurons that are related to the control of vertical and torsional saccadic eye movements. In the present-study, complimentary light microscopic anterograde biocytin and retrograde horseradish peroxidase experiments have been performed to determine the organization of premotor neurons in the riLF in the cat that are related intimately to the vertical motoneuron populations in the oculomotor and trochlear nuclei. The results indicate a rostral-caudal topographic arrangement of neurons in the riMLF that is related to the target projections to vertical downward(inferior rectus and superior oblique) and vertical upward (superior rectus and inferior oblique) retrograde studies are consistent in demonstrating the tendency for downward and upward riMLF neurons to be spatially separated by a distance of approximately 0.5 mm in the rostral motoneurons, however, are bilateral and presumably provide one means for assuring the conjugacy of vertical saccadic eye movements. Since premotor burst neurons that encode parameters for upward or downward saccades are intermingled within the riMLF, and excitatory and inhibitory premotor neurons also coexist in this region, the findings from this study suggest that subregions of the riMLF contain coexistent populations of excitatory and inhibitory neurons that are related to opposite directions of vertical eye movements. The spatial segregation of excitatory premotor neurons in the riMLF that are related to vertical upward versus downward movements furthermore provides a basis for the interpretation of vertical upward and/or downward gaze palsies that might result from discrete lesions at the mesodiencephalic junction in humans
Reliability of Thickness Measurements of the Dorsal Muscles of the Upper Cervical Spine: An Ultrasonographic Study
No full textSTUDY DESIGN: Clinical measurement, reliability. OBJECTIVES: To examine the intraday intrarater reliability of measuring thickness of the upper dorsal neck muscles at rest, as well as at 50% of maximum voluntary isometric contraction (MVIC) , for upper cervical extension. BACKGROUND: Methodology for measuring the thickness of the lower dorsal neck muscles, including semispinalis capitis and multifidus muscles, during contraction using ultrasonography has been established. Thickness measurements for the upper dorsal neck muscles have not been documented. METHODS: Ten subjects (21 to 30 years of age) without neck pain and headache were recruited. Their upper dorsal neck muscles were measured both at rest and during 50% MVIC for upper cervical extension in sitting position using rehabilitative ultrasound imaging (RUST). Muscles measured included the rectus capitis posterior major, oblique capitis superior, semispinalis capitis, and splenius capitis. All measurements were repeated after 10 minutes of rest, on the same day, by the same rater. Descriptive statistics were supplemented by calculations of intraclass correlation coefficient (ICC3,1 , standard error of measurement (SEM), within-subject coefficient of variation (CVw), and minimal detectable change (MDC). RESULTS: ICC3,1 results ranged from 0.87 to 0. 99 for thickness measurements made at rest and from 0.90 to 0.98 for thickness measurements made with a 50% MVIC. The SEMs for thickness measurements at rest and at 50% MVIC ranged from 0.11 to 0.46 mm and 0.23 to 0.52 mm, while the CV(w)s ranged from 3.5% to 6.1% and 3.7% to 6.4%, and MDC95 ranged from 0.35 to 1.46 mm and 0.73 to 1.65 mm, respectively. The thickness of all upper dorsal neck muscles measured during a 50% MVIC was greater than when measured at rest (P < .029). CONCLUSION: Thickness measurements of the upper dorsal neck muscles using RUSI were reliable both at rest and during a 50% effort isometric contraction
Position accuracy and electromyographic responses during head reposition in young adults with chronic neck pain
No full textOrganization and Synaptic Connections of Premotor Neurones Related to Vertical Saccadic Movements in the Cat
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