Vestibular inputs make a key contribution to the sense of one’s own spatial location. While the effects of vestibular stimulation on visuo-spatial processing in neurological patients have been extensively described, the normal contribution of vestibular inputs to spatial perception remains unclear. To address this issue, we used a line bisection task to investigate the effects of galvanic vestibular stimulation (GVS) on spatial perception, and on the transition between near and far space. Brief left-anodal and right-cathodal GVS or right-anodal and left-cathodal GVS were delivered. A sham stimulation condition was also included. Participants bisected lines of different lengths at six distances from the body using a laser pointer. Consistent with previous results, our data showed an overall shift in the bisection bias from left to right as viewing distance increased. This pattern suggests leftward bias in near space, and rightward bias in far space. GVS induced strong polarity dependent effects in spatial perception, broadly consistent with those previously reported in patients: left-anodal and right-cathodal GVS induced a leftward bisection bias, while right-anodal and left-cathodal GVS reversed this effect, and produced bisection bias toward the right side of the space. Interestingly, the effects of GVS were comparable in near and far space. We speculate that vestibular-induced biases in space perception may optimize gathering of information from different parts of the environment.
This study looked at whether drivers overtaking a bicyclist changed the proximities of their passes in response to the level of experience and skill signalled by the bicyclist’s appearance. Seven outfits were tested, ranging from a stereotypical sport rider’s outfit, portraying high experience and skill, to a vest with ‘novice cyclist’ printed on the back, portraying low experience. A high-visibility bicycling jacket was also used, as were two commercially available safety vests, one featuring a prominent mention of the word ‘police’ and a warning that the rider was video-recording their journey, and one modelled after a police officer’s jacket but with a letter changed so it read ‘POLITE’. An ultrasonic distance sensor recorded the space left by vehicles passing the bicyclist on a regular commuting route. 5690 data points fulfilled the criteria for the study and were included in the analyses. The only outfit associated with a significant change in mean passing proximities was the police/video-recording jacket. Contrary to predictions, drivers treated the sports outfit and the ‘novice cyclist’ outfit equivalently, suggesting they do not adjust overtaking proximity as a function of a rider’s perceived experience. Notably, whilst some outfits seemed to discourage motorists from passing within 1m of the rider, approximately 1-2% of overtakes came within 50 cm no matter what outfit was worn. This suggests there is little riders can do, by altering their appearance, to prevent the very closest overtakes; it is suggested that infrastructural, educational or legal measures are more promising for preventing drivers from passing extremely close to bicyclists.
- Journal of strength and conditioning research / National Strength & Conditioning Association
- Published about 6 years ago
The purpose of this study was to compare the distances covered during a 11-a-side soccer match after players had consumed either a high carbohydrate (CHO) or a low CHO diet. Twenty two male professional soccer players formed two teams (A and B), of similar age, body characteristics, and training experience. The two teams played against each other twice with a week interval between. For 3.5 days before the 1 match the players of team A followed a high CHO diet that provided 8 g CHO per Kg body mass (BM) (HC), whereas team B players followed a low CHO diet that provided 3 g CHO / Kg BM (LC) for the same time period. Before the 2 match the dietary treatment was reversed and followed for the same time period. Training during the study was controlled and distances covered were measured using GPS technology. Every player covered a greater total distance in HC compared to the distance covered in LC (HC: 9380 ± 98 m vs. LC: 8077 ± 109 m; p< 0.01). All distances covered from easy jogging (7.15 Km.h) to sprinting (24.15 Km.h) were also higher in HC compared to LC (p< 0.01). When players followed the HC treatment won the match (Team A vs. Team B: 3-1 for the first game and 1-2 for the 2 game). The HC diet probably helped players to cover a greater distance compared to LC. Soccer players should avoid eating a low (3 g CHO / Kg BM) CHO diet 3-4 days before an important soccer match and have a high CHO intake that provides at least 8 g CHO / Kg BM.
To evaluate the quality of evidence reporting, breadth of coverage, and timeliness of content updating of 10 selected online medical texts.
Abstract The aims of this study were to examine the 1) individual playing area, 2) length and width of the rectangle encompassing the individual playing area and 3) distance between the goalkeepers and their nearest team-mates during professional soccer matches and compare these to previously reported pitch sizes for small-sided games (SSGs). Data were collected from four Spanish La Liga matches of the 2002-03 season, and notated post-event using the Amisco® system. The pitch sizes obtained from real matches were smaller and different from those used previously for SSGs. In addition, the current pitch sizes show significant (P < 0.001) effect of ball location in all variables examined. For example, overall individual playing area (F [5, 2562] = 19.99, P < 0.001, η(2 )= 0.04) varied significantly across six different zones of the pitch. Based on these empirical results, pitch sizes with individual playing areas ranging from 65 m(2) to 110 m(2) and length to width ratio of 1:1 and 1:1.3 are generally recommended for training tactical aspects according to different phases of play. It is possible to design SSGs with a more valid representation of the tactical conditions experienced in full-size matches and their use may improve the training effect of tactical aspects of match performance in soccer.
- IEEE transactions on pattern analysis and machine intelligence
- Published about 6 years ago
We consider the problem of categorizing video sequences of dynamic textures, i.e., nonrigid dynamical objects such as fire, water, steam, flags, etc. This problem is extremely challenging because the shape and appearance of a dynamic texture continuously change as a function of time. State-of-the-art dynamic texture categorization methods have been successful at classifying videos taken from the same viewpoint and scale by using a Linear Dynamical System (LDS) to model each video, and using distances or kernels in the space of LDSs to classify the videos. However, these methods perform poorly when the video sequences are taken under a different viewpoint or scale. In this paper, we propose a novel dynamic texture categorization framework that can handle such changes. We model each video sequence with a collection of LDSs, each one describing a small spatiotemporal patch extracted from the video. This Bag-of-Systems (BoS) representation is analogous to the Bag-of-Features (BoF) representation for object recognition, except that we use LDSs as feature descriptors. This choice poses several technical challenges in adopting the traditional BoF approach. Most notably, the space of LDSs is not euclidean; hence, novel methods for clustering LDSs and computing codewords of LDSs need to be developed. We propose a framework that makes use of nonlinear dimensionality reduction and clustering techniques combined with the Martin distance for LDSs to tackle these issues. Our experiments compare the proposed BoS approach to existing dynamic texture categorization methods and show that it can be used for recognizing dynamic textures in challenging scenarios which could not be handled by existing methods.
PURPOSE: This study compared the status of suture knots immediately after repair and after shoulder motion to evaluate the possibility of movement-induced knot migration to a location nearer the glenoid. METHODS: We included 10 shoulders from 5 cadavers in the study. After posterior capsulotomy, a Bankart lesion was created. A capsulolabral repair was then performed with 3 knot-tying suture anchors. All knots were positioned on the capsular side, far from the articular surface. After the repair was complete, a photograph was taken with a metal rod placed to reference absolute distance. After passive pendulum motion was applied, another photograph was taken. The length of the suture strand from the knot base to the anchor insertion site was measured during both the initial repair and post-motion periods. RESULTS: Initial distances were 4.83 ± 1.09 mm for the inferior knot, 4.70 ± 0.97 mm for the middle knot, and 3.84 ± 1.25 mm for the superior knot. After motion, the distances were 3.52 ± 1.21 mm (P = .01), 3.07 ± 0.81 mm (P < .001), and 2.69 ± 1.18 mm (P = .016), respectively. Additional observations showed changes in direction and security of the knot. The change in knot direction from an initial orientation facing the capsular side to a new orientation facing the glenoid was observed in 5 of 10 inferior, 7 of 10 middle, and 6 of 10 superior knots. In addition, knot loosening was noted for the last half-hitches in 4 inferior knots and 1 middle knot. CONCLUSIONS: Intentional placement of suture knots away from the joint surface was not maintained after motion at the shoulder. CLINICAL RELEVANCE: Movement-induced knot migration may be detrimental to articular cartilage in the event that a knot becomes interposed between the glenoid and humeral head.
The study evaluated the potential mismatch between classroom furniture dimensions and anthropometric characteristics of 978 Iranian high school students (498 girls, 480 boys), aged 15-18 years. Nine anthropometric measurements (stature, sitting height, sitting shoulder height, popliteal height, hip breadth, elbow-seat height, buttock-popliteal length, buttock-knee length and thigh clearance) and five dimensions from the existing classroom furniture were measured and then compared together (using match criterion equations) to identify any potential mismatch between them. The results indicated a considerable mismatch between body dimensions of the students and the existing classroom furniture, with seat height (60.9%), seat width (54.7%) and desktop height (51.7%) being the furniture dimensions with a higher level of mismatch. The levels of mismatch varied between the high-school grade levels and between genders, indicating their special requirements and possible problems. The proposed dimensions of the classroom furniture more appropriate for the students were given. This additional information on students' anthropometry can be used by local furniture industries as a starting point for designing more appropriate furniture for school children, or used by schools to aid in furniture selection.
A neutral marker of the electroosmotic flow (EOF) can gain a nonzero effective mobility because of its possible interaction with a charged complexing agent, such as a chiral selector in capillary electrophoresis. We determined effective mobilities of four compounds often used as EOF markers (dimethyl sulfoxide, mesityl oxide, nitromethane and thiourea) in the background electrolyte (BGE) containing sulfated β-cyclodextrin (60g/L). All the compounds studied were measurably mobilized by their interaction with the selector. The highest effective mobility (-3.0·10(-9) m(2) s(-1) V(-1) ) was observed for thiourea and the lowest (-1.5·10(-9) m(2) s(-1) V(-1) ) for dimethyl sulfoxide and nitromethane. The mobilities were determined by a new two-detector pressure mobilization method (2d method), which we propose, and the results were confirmed by standard capillary electrophoresis measurements. In the 2d method, one marker zone is situated in the BGE containing the charged selector, while the second marker zone is surrounded with a selector free BGE, which prevents its complexation. The initial distance between the two marker zones equals the capillary length from the inlet to the first detector. After a brief voltage application, the final distance between the marker zones is determined based on known capillary length from the first to the second detector. The difference between these two distances determines the effective mobility.
PURPOSE: The aim of this study was to define a safety margin for coracoid process osteotomy that does not compromise the coracoclavicular ligaments and that can be used in the coracoid transfer procedures. METHODS: Thirty shoulders from 15 cadavers were dissected, exposing the coracoid process and attached anatomic structures. The distance of the insertion of these structures to the coracoid process apex was measured. RESULTS: The average length of the coracoid process was 4.26 ± 0.26 cm. The average width and height at the tip were 2.11 ± 0.2 and 1.49 ± 0.12 cm, respectively. The average distance from the tip to the anterior and posterior margin of the pectoralis minor was 0.1 ± 1.17 and 1.59 ± 0.27 cm, respectively. The average distance from the tip to the posterior margin of the coracoacromial ligament was 2.79 ± 0.33 cm. The average distance from the apex to the most anterior part of the trapezoid ligament was 3.33 ± 0.38 cm. We obtained a constant value of 0.85 cm for this measure, and the value increased with each 1.0-cm increase in the distance from the tip to the posterior margin of the pectoralis minor. The safety margin for osteotomy (i.e., available bone distance for the coracoid process transfer) was 2.64 cm. CONCLUSIONS: This study established a safety margin of 2.64 cm for the osteotomy of the coracoid process and its relation with the posterior margin of the pectoralis minor. The anatomic descriptions of bone and soft tissue, as well as a measure of correlation for the safety margin of the coracoid, provide tools for surgeons performing anatomic surgical procedures to correct glenohumeral instability with significant bone loss. CLINICAL RELEVANCE: Knowing the safety margin allows the surgeon to perform a safe osteotomy without direct visualization of the coracoclavicular ligaments attachments, thereby making procedures more anatomic.