Rear Admiral Richard Evelyn Byrd : a Biography

Commemorating the dedication of Richard Evelyn Bird Hall of the Virginia Institute of Marine Science

COMPARISON OF RIGHT VS. LEFT LEG GRF LANDING SYMMETRY FOR HEALTHY AND OVERUSE INJURY-PRONE RECREATIONAL ATHLETES

PURPOSE AND METHODS The purpose of the study was to compare right versus left leg symmetry during landing for healthy (n = 10) and overuse injury-prone (n = 10) recreational athletes. Landing symmetry was evaluated by examining vertical ground reaction force (GRF; 1000 Hz) magnitude and temporal variables for each leg and subject group while landing from three different heights (50, 100, and 200% of maximum vertical jump, MVJ). Magnitudes of the first (Fl) and second (F2) maximum force values were identified along with the temporal occurrences of these events (T1 and T2, respectively). Vertical GRF pattern consistency varied among subjects and across heights, therefore, when Fl and F2 could not be individually identified the maximum force magnitude and temporal values for the landing phase were assigned to the F2 and T2 variables, respectively. The F2 and T2 values were utilized to evaluate differences between legs (one-way Analysis of Variance, ANOVA; = 0.05) for each group and landing height. Additionally, GRF pattern consistency between right and left legs (for both subject groups) was monitored by a tally which tracked the number of unimodal (single peak) curves for each landing height. RESULTS Results of the ANOVA procedures indicated no significant differences (p > 0.05) between the right and left side GRF magnitude or temporal variables for the healthy subject group. The injury prone group exhibited significant right-left side differences for the 50% MVJ height (p < 0.01; right greater than left) and for the 100% MVJ height condition (p < 0.05; right greater than left). No right-left temporal differences were observed for the injury prone group. Results of the descriptive GRF tally for the occurrence of unimodal landing curve patterns suggest that the injury prone group might have been more consistent between legs in producing traditional bimodal GRF-time histories. A unimodal curve was defined as a GRF-time history that did not follow the typical bimodal (Fl-toe, F2-heel) landing pattern. The 50% MVJ height elicited a right-left unimodal curve count of 21 and 30, respectively, for the healthy group and 19 and 19, respectively, for the injury prone subjects. For the 100% MVJ height condition the healthy group exhibited a total (sum of all subjects) of two right side and three left side unimodal curves, while the injury prone group exhibited no unimodal curves from either leg. No unimodal curves were detected for either subject group while landing from the 200% MVJ height. CONCLUSIONS The functional significance of these results is not clear. However, one might speculate that the asymmetrical GRF magnitude values observed for the injury prone group are related to their injury history, although the causeeffect relationship cannot be determined from these data. The number of differences between right and left leg unimodal curves might be related to the amount of movement variability exhibited by each subject group. The fewer total number of unimodal curves and the fewer number of right-left differences suggest less performance variability for theinjury prone group

EFFECTS OF BACKWARD WALKING AS A MODALITY FOR LOW BACK PAIN REDUCTION IN ATHLETES

The therapeutic effectiveness of backward walking for treatment of low back pain (LBP) was examined among athletes experiencing LBP and healthy non-athletes. All participants were pre-tested walking backward, performed 10-15 mins of backward walking three days/week for three weeks and were post-tested. Low back sagittal and coronal plane range of motion, shock attenuation (SA), stride length (SL), stride rate (SR), velocity and LBP were evaluated (&#945;=0.05). All variables were significantly different between groups, excluding SA. Velocity, SL and SR were significantly different pre vs post. Owing to the clinical nature of this study, single-subject analyses were performed and identified unique individual responses to the intervention. Results suggest that backward walking may assist some athletes presenting with LBP

Eruption of Shallow Crystal Cumulates during Explosive Phonolitic Eruptions on Tenerife, Canary Islands

The recent eruptive history on the island of Tenerife is characterized in part by the presence of zoned phonolitic ignimbrites, some of which prominently display two types of juvenile clasts (i.e. light-colored, aphyric pumices alongside darker, more crystal-rich pumices, here dubbed ‘crystal-poor' and ‘crystal-rich', respectively). Petrographic observation of the crystal-rich pumices reveals intensely resorbed and intergrown mineral textures, consistent with the system reaching a high crystallinity, followed by perturbation and remobilization prior to eruption. Some trace elements show anomalous concentrations in such crystal-rich pumices (e.g. bulk Ba > 2000 ppm alongside low Zr and a positive Eu anomaly) indicative of crystal accumulation (of feldspar ± biotite). Many biotite and feldspar crystals are reversely zoned, with rim concentrations that are high in Ba but low in Sr, implying crystallization from an ‘enriched' melt, potentially derived from remobilization by partial melting of the aforementioned cumulate zones. Given (1) the presence of cumulates in the eruptive record on Tenerife and a bimodality of pumice textures, (2) the presence of three dominant compositions (basanite, phonotephrite, phonolite, separated by compositional gaps) in the volcanic record, and (3) abundant support for crystal fractionation as the dominant drive for magmatic evolution in Tenerife, it is hypothesized that crystal-poor magmas are extracted from mushy reservoirs in both the lower and upper crust. The thermodynamic software MELTS is used to test a polybaric differentiation model whereby phonolites (sensu lato) are generated by extraction of residual liquids from an intermediate-crystallinity phonotephritic mush in the upper crust, which is in turn generated from the residual liquids of an intermediate-crystallinity basanitic mush at deeper levels. Latent heat spikes following crystallization of successive phases in the upper crustal reservoir provide a thermal buffering mechanism to slow down cooling and crystallization, permitting enhanced melt extraction at a particular crystallinity interval (mostly ∼40-60 vol. % crystals). MELTS modeling typically fits the observed chemical data adequately, although some major elements (mostly Al2O3) also indicate partial ‘cannibalization' of feldspar along with some magma mixing (and potentially minor crustal contamination

Impaired Self-Other Distinction and Subcortical Gray-Matter Alterations Characterize Socio-Cognitive Disturbances in Multiple Sclerosis

Introduction: Recent studies of patients with multiple sclerosis (MS) have revealed disturbances in distinct components of social cognition, such as impaired mentalizing and empathy. The present study investigated this socio-cognitive profile in MS patients in more detail, by examining their performance on tasks measuring more fundamental components of social cognition and any associated disruptions to gray-matter volume (GMV). Methods: We compared 43 patients with relapse-remitting MS with 43 age- and sex-matched healthy controls (HCs) on clinical characteristics (depression, fatigue), cognitive processing speed, and three aspects of low-level social cognition; specifically, imitative tendencies, visual perspective taking, and emotion recognition. Using voxel-based morphometry, we then explored relationships between GMV and these clinical and behavioral measures. Results: Patients exhibited significantly slower processing speed, poorer perspective taking, and less imitation compared with HCs. These impairments were related to reduced GMV throughout the putamen, thalami, and anterior insula, predominantly in the left hemisphere. Surprisingly, differences between the groups in emotion recognition were not significant. Conclusion: Less imitation and poorer perspective taking indicate a cognitive self-bias when faced with conflicting self- and other-representations. This suggests that impaired self-other distinction, and an associated subcortical pattern of GM atrophy, might underlie the socio-cognitive disturbances observed in MS

Structural, Electronic, and Magnetic Properties of MnO

We calculate the structural, electronic, and magnetic properties of MnO from first principles, using the full-potential linearized augmented planewave method, with both local-density and generalized-gradient approximations to exchange and correlation. We find the ground state to be of rhombohedrally distorted B1 structure with compression along the [111] direction, antiferromagnetic with type-II ordering, and insulating, consistent with experiment. We show that the distortion can be understood in terms of a Heisenberg model with distance dependent nearest-neighbor and next-nearest-neighbor couplings determined from first principles. Finally, we show that magnetic ordering can induce significant charge anisotropy, and give predictions for electric field gradients in the ground-state rhombohedrally distorted structure.Comment: Submitted to Physical Review B. Replaced: regenerated figures to resolve font problems in automatically generated pd