Latitude and longitude vertical disparities

The literature on vertical disparity is complicated by the fact that several different definitions of the term “vertical disparity” are in common use, often without a clear statement about which is intended or a widespread appreciation of the properties of the different definitions. Here, we examine two definitions of retinal vertical disparity: elevation-latitude and elevation-longitude disparities. Near the fixation point, these definitions become equivalent, but in general, they have quite different dependences on object distance and binocular eye posture, which have not previously been spelt out. We present analytical approximations for each type of vertical disparity, valid for more general conditions than previous derivations in the literature: we do not restrict ourselves to objects near the fixation point or near the plane of regard, and we allow for non-zero torsion, cyclovergence, and vertical misalignments of the eyes. We use these expressions to derive estimates of the latitude and longitude vertical disparities expected at each point in the visual field, averaged over all natural viewing. Finally, we present analytical expressions showing how binocular eye position—gaze direction, convergence, torsion, cyclovergence, and vertical misalignment—can be derived from the vertical disparity field and its derivatives at the fovea

A graph-theory method for pattern identification in geographical epidemiology - a preliminary application to deprivation and mortality

Background: Graph theoretical methods are extensively used in the field of computational chemistry to search datasets of compounds to see if they contain particular molecular substructures or patterns. We describe a preliminary application of a graph theoretical method, developed in computational chemistry, to geographical epidemiology in relation to testing a prior hypothesis. We tested the methodology on the hypothesis that if a socioeconomically deprived neighbourhood is situated in a wider deprived area, then that neighbourhood would experience greater adverse effects on mortality compared with a similarly deprived neighbourhood which is situated in a wider area with generally less deprivation. Methods: We used the Trent Region Health Authority area for this study, which contained 10,665 census enumeration districts (CED). Graphs are mathematical representations of objects and their relationships and within the context of this study, nodes represented CEDs and edges were determined by whether or not CEDs were neighbours (shared a common boundary). The overall area in this study was represented by one large graph comprising all CEDs in the region, along with their adjacency information. We used mortality data from 1988-1998, CED level population estimates and the Townsend Material Deprivation Index as an indicator of neighbourhood level deprivation. We defined deprived CEDs as those in the top 20% most deprived in the Region. We then set out to classify these deprived CEDs into seven groups defined by increasing deprivation levels in the neighbouring CEDs. 506 (24.2%) of the deprived CEDs had five adjacent CEDs and we limited pattern development and searching to these CEDs. We developed seven query patterns and used the RASCAL (Rapid Similarity Calculator) program to carry out the search for each of the query patterns. This program used a maximum common subgraph isomorphism method which was modified to handle geographical data. Results: Of the 506 deprived CEDs, 10 were not identified as belonging to any of the seven groups because they were adjacent to a CED with a missing deprivation category quintile, and none fell within query Group 1 (a deprived CED for which all five adjacent CEDs were affluent). Only four CEDs fell within Group 2, which was defined as having four affluent adjacent CEDs and one non-affluent adjacent CED. The numbers of CEDs in Groups 3-7 were 17, 214, 95, 81 and 85 respectively. Age and sex adjusted mortality rate ratios showed a non-significant trend towards increasing mortality risk across Groups (Chi-square = 3.26, df = 1, p = 0.07). Conclusion: Graph theoretical methods developed in computational chemistry may be a useful addition to the current GIS based methods available for geographical epidemiology but further developmental work is required. An important requirement will be the development of methods for specifying multiple complex search patterns. Further work is also required to examine the utility of using distance, as opposed to adjacency, to describe edges in graphs, and to examine methods for pattern specification when the nodes have multiple attributes attached to them

Effects of inter-limb asymmetries on physical and sports performance: a systematic review

The prevalence of inter-limb asymmetries has been reported in numerous studies across a wide range of sports and physical qualities; however, few have analysed their effects on physical and sports performance. A systematic review of the literature was undertaken using the Medline and SPORT Discus databases, with all articles required to meet a specified criteria based on a quality review. Eighteen articles met the inclusion criteria, relating participant asymmetry scores to physical and sports performance measures. The findings of this systematic review indicate that inter-limb differences in strength may be detrimental to jumping, kicking and cycling performance. When inter-limb asymmetries are quantified during jumping based exercises, they have been primarily used to examine their association with change of direction speed with mixed findings. Inter-limb asymmetries have also been quantified in anthropometry, sprinting, dynamic balance and sport-specific actions, again with inconsistent findings. However, all results have been reported using associative analysis with physical or sport performance metrics with no randomised controlled trials included. Further research is warranted to understand the mechanisms that underpin inter-limb differences and the magnitude of performance changes that can be accounted for by these asymmetries

Training methods and considerations for practitioners to reduce interlimb asymmetries

Inter-limb asymmetries have been a common source of investigation in recent years with the majority of studies highlighting its prevalence in a range of athletic tasks. Few have tested whether reducing inter-limb differences are required for improved physical performance. Furthermore, there are a number of considerations that may exist which practitioners should consider prior to starting training interventions to reduce these differences. This article will discuss the available body of literature pertaining to the reduction of inter-limb asymmetries to date and provide example training programs to show how they can be addressed if their reduction is deemed necessary

Fractionalization and confinement in the U(1) and Z2Z_2 gauge theories of strongly correlated systems

Recently, we have elucidated the physics of electron fractionalization in strongly interacting electron systems using a $Z_2$ gauge theory formulation. Here we discuss the connection with the earlier U(1) gauge theory approaches based on the slave boson mean field theory. In particular, we identify the relationship between the holons and Spinons of the slave-boson theory and the true physical excitations of the fractionalized phases that are readily described in the $Z_2$ approach.Comment: 4 page

Tunneling spectroscopy studies of aluminum oxide tunnel barrier layers

We report scanning tunneling microscopy and ballistic electron emission microscopy studies of the electronic states of the uncovered and chemisorbed-oxygen covered surface of AlOx tunnel barrier layers. These states change when chemisorbed oxygen ions are moved into the oxide by either flood gun electron bombardment or by thermal annealing. The former, if sufficiently energetic, results in locally well defined conduction band onsets at ~1 V, while the latter results in a progressively higher local conduction band onset, exceeding 2.3 V for 500 and 600 C thermal anneals

Reactive strength index and its associations with measures of physical and sports performance: a systematic review with meta-analysis

Reactive strength index (RSI) is used frequently in the testing and monitoring of athletes. Associations with sports performance measures may vary dependent on the task but a literature synthesis has not been performed. The aim of this meta-analysis was to examine associations between RSI measured during rebound jumping tasks and measures of strength, linear and change of direction speed, and endurance performance. A systematic literature search with meta-analysis was conducted using databases PubMed, SPORTDiscus, Web of Science, and Ovid. Inclusion criteria required studies to (1) examine the relationship between RSI and an independent measure of physical or sporting performance for at least one variable; and (2) provide rebound test instructions to minimise ground contact time and maximise displacement of the jump. Methodological quality was assessed using a modified version of the Downs and Black Quality Index tool. Heterogeneity was examined via the Q statistic and I . Pooled effect sizes were calculated using a random-effects model, with Egger's regression test used to assess small study bias (inclusive of publication bias). Of the 1320 citations reviewed, a total of 32 studies were included in this meta-analysis. RSI was significantly and moderately associated with strength (isometric: r = 0.356 [95% CI 0.209-0.504]; isotonic: r = 0.365 [0.075-0.654]; pooled strength measures: r = 0.339 [0.209-0.469]) and endurance performance (r = 0.401 [0.173-0.629]). Significant moderate and negative associations were indicated for acceleration (r = - 0.426 [- 0.562 to - 0.290]), top speed (r = - 0.326 [- 0.502 to - 0.151]), and significant large negative associations were noted for change of direction speed (r = - 0.565 [- 0.726 to - 0.404]). Heterogeneity was trivial to moderate across all measures (I  = 0-66%), and significant for isotonic strength and change of direction speed (p < 0.1). Evidence of small study bias was apparent for both acceleration and change of direction speed (p < 0.05). We identified primarily moderate associations between RSI and independent measures of physical and sporting performance, and the strength of these relationships varied based on the task and physical quality assessed. The findings from this meta-analysis can help practitioners to develop more targeted testing and monitoring processes. Future research may wish to examine if associations are stronger in tasks that display greater specificity. [Abstract copyright: © 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.

Asymmetries of the lower limb: the calculation conundrum in strength training and conditioning

Asymmetry detection has been a topic of interest in the strength and conditioning (S&C) literature with numerous studies proposing many different equations for calculating between-limb differences. However, there does not appear to be a clear delineation as to which equation should be used when quantifying asymmetries. Consequently, the authors have uncovered nine different equations which pose confusion as to which method the S&C specialist should employ during data interpretation. This article aims to identify the different equations currently being used to calculate asymmetries and offer practitioners a guide as to which method may be most appropriate when measuring asymmetries

Vertical and horizontal asymmetries are related to slower sprinting and jump performance in elite youth female soccer players

Inter-limb asymmetries have been shown to be greater during vertical jumping compared to horizontal jumping. Notable inter-limb differences have also been established at an early age in male youth soccer players. Furthermore, given the multi-planar nature of soccer, establishing between-limb differences from multiple jump tests is warranted. At present, a paucity of data exists regarding asymmetries in youth female soccer players and their effects on physical performance. The aims of this study were to quantify inter-limb asymmetries from unilateral jump tests and examine their effects on speed and jump performance. Nineteen elite youth female soccer players performed a single leg countermovement jump (SLCMJ), single, triple, and crossover hops for distance and a 20 m sprint test. Test reliability was good to excellent (ICC = 0.81-0.99) and variability acceptable (CV = 1.74-5.42%). A one-way ANOVA highlighted larger asymmetries from the SLCMJ compared to all other jump tests (p < 0.05). Pearson’s correlations portrayed significant relationships between vertical asymmetries from the SLCMJ and slower sprint times (r = 0.49-0.59). Significant negative relationships were also found between horizontal asymmetries during the triple hop test and horizontal jump performance (r = -0.47 to -0.58) and vertical asymmetries during the SLCMJ and vertical jump performance (r = -0.47 to -0.53). The results from this study highlight that the SLCMJ appears to be the most appropriate jump test for identifying between-limb differences with values ~12% showing negative associations with sprint times. Furthermore, larger asymmetries are associated with reduced jump performance and would appear to be direction-specific. Practitioners can use this information as normative data to be mindful of when quantifying inter-limb asymmetries and assessing their potential impact on physical performance in youth female soccer players

Effects of soccer match-play on unilateral jumping and Inter-limb asymmetry: a repeated measures design

The aims of the present study were twofold: 1) determine the effects of repeated soccer match-play on unilateral jump performance and inter-limb asymmetries and, 2) examine associations between asymmetry and commonly reported external load variables collected during competition. Single leg countermovement jumps (SLCMJ) and drop jumps (SLDJ) were collected pre and immediately post five soccer matches in elite academy soccer players. GPS data was also collected each match as part of the routine match-day procedures. SLCMJ height and concentric impulse showed significant reductions post-matches (p 0.05; ES: -0.05 to -0.13). SLDJ height and reactive strength also showed significant reductions post-matches (p < 0.01; ES: -0.39 to -0.58). No meaningful reductions in asymmetry were present at the group level, but individual responses were highly variable. Significant associations between post-match reactive strength asymmetry and explosive distance (r = 0.29; p < 0.05), relative explosive distance (r = 0.34; p < 0.05), high speed running (r = 0.35; p < 0.05) and relative high speed running (r = 0.44; p < 0.01). These findings show that unilateral jump tests are more appropriate than asymmetry to detect real change post soccer competition and practitioners should be cautious about using asymmetry to inform decision-making during the temporal recovery period