Summary1. Over recent years, a major breakthrough in marine animal tracking has occurred with the advent of Fastloc-GPS that provides highly accurate location data even for animals that only surface briefly such as sea turtles, marine mammals and penguins. 2. We assessed the accuracy of Fastloc-GPS locations using fixed trials of tags in which >45 000 locations were obtained. Procedures for determining the speed of travel and heading were developed by simulating tracks and then adding Fastloc-GPS location errors. The levels of detail achievable for speed and heading estimates were illustrated by using empirical Fastloc-GPS data for a green turtle (Chelonia mydas, Linnaeus, 1758) travelling over 3000 km across the Indian Ocean. 3. The accuracy of Fastloc-GPS locations varied as a function of the number of GPS satellites used in the location calculation. For example, when Fastloc-GPS locations were calculated using 4 GPS satellites, 50% of locations were within 36 m and 95% within 724 m of the true position. These values improved to 18 and 70 m, respectively, when 6 satellites were used. Simulations indicated that for animals travelling around 2Á5 km h À1 (e.g. turtles, penguins and seals) and depending on the number of satellites used in the location calculation, robust speed and heading estimates would usually be obtained for locations only 1-6 h apart. 4. Fastloc-GPS accuracy is several orders of magnitude better that conventional Argos tracking or light-based geolocation and consequently will allow new insights into small-scale movement patterns of marine animals.
An exercise programme that aims to enhance motor control of the cervical spine improves the specificity of neck muscle activity and reduces pain and disability in patients with neck pain.
Background: Patients with neck pain normally showed alterations in cervical motion and pressure pain sensitivity. Cervical joints show scattered motions opposite to (anti-directional) the primary motion direction (prodirectional) during dynamic cervical flexion and extension. This study aimed to assess dynamic cervical joint motion and pressure pain sensitivity when pain originated from different cervical muscles which may have clinical relevance in diagnosis of impairments related with neck pain. Methods: Fluoroscopic video recordings of cervical flexion and extension were collected from fifteen healthy subjects before and during hypertonic saline-induced pain in right multifidus and trapezius muscles. Cervical flexion and extension motions were divided into 10 epochs with respect to time. Pro-directional, anti-directional, and total joint motion were extracted across epochs as well as joint motion variability. Pressure pain thresholds (PPTs) were assessed bilaterally over C2/C3 and C5/C6 facet joints. Findings: Compared with baseline: 1) Multifidus muscle pain increased the C3/C4 anti-directional motion (P < 0.01), decreased the C6/C7 anti-directional motion (P < 0.05) during extension, and redistributed total joint motion between joints and between half ranges during flexion (P < 0.05). 2) Trapezius muscle pain decreased pro-directional motion (P < 0.05), anti-directional motion (P < 0.05), and joint motion variability (P < 0.05) during extension. 3) Trapezius and multifidus muscle pain increased the PPTs bilaterally over C2/C3 and on the left side of C5/C6 facet joints (P < 0.05). Interpretation: The direction of motion influenced the effects of experimental muscle pain on dynamic cervical joint kinematics, and deep muscle pain showed local effects on individual joints while superficial muscle pain showed global effects spread to all joints.
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