Within-guild dietary discrimination from 3-D textural analysis of tooth microwear in insectivorous mammals

Resource exploitation and competition for food are important selective pressures in animal evolution. A number of recent investigations have focused on linkages between diversification, trophic morphology and diet in bats, partly because their roosting habits mean that for many bat species diet can be quantified relatively easily through faecal analysis. Dietary analysis in mammals is otherwise invasive, complicated, time consuming and expensive. Here we present evidence from insectivorous bats that analysis of three-dimensional (3-D) textures of tooth microwear using International Organization for Standardization (ISO) roughness parameters derived from sub-micron surface data provides an additional, powerful tool for investigation of trophic resource exploitation in mammals. Our approach, like scale-sensitive fractal analysis, offers considerable advantages over twodimensional (2-D) methods of microwear analysis, including improvements in robustness, repeatability and comparability of studies. Our results constitute the first analysis of microwear textures in carnivorous mammals based on ISO roughness parameters. They demonstrate that the method is capable of dietary discrimination, even between cryptic species with subtly different diets within trophic guilds, and even when sample sizes are small. We find significant differences in microwear textures between insectivore species whose diet contains different proportions of ‘hard’ prey (such as beetles) and ‘soft’ prey (such as moths), and multivariate analyses are able to distinguish between species with different diets based solely on their tooth microwear textures. Our results show that, compared with previous 2-D analyses of microwear in bats, ISO roughness parameters provide a much more sophisticated characterization of the nature of microwear surfaces and can yield more robust and subtle dietary discrimination. ISO-based textural analysis of tooth microwear thus has a useful role to play, complementing existing approaches, in trophic analysis of mammals, both extant and extinct

Accordance to the Dietary Approaches to Stop Hypertension diet pattern and cardiovascular disease in a British, population-based cohort.

The dietary approaches to stop hypertension (DASH) diet could be an important population-level strategy to reduce cardiovascular disease (CVD) in the UK, but there is little UK-based evidence on this diet pattern in relation to CVD risk. We tested whether dietary accordance with DASH was associated with risk of CVD in a population-based sample of 23,655 UK adults. This prospective analysis of the EPIC-Norfolk cohort study analysed dietary intake (assessed using a validated food frequency questionnaire) to measure accordance with DASH, based on intakes of eight food groups and nutrients, ranking the sample into quintiles. Cox proportional hazards regression models tested for association between DASH accordance and incident stroke, ischemic heart disease (IHD) and total incident CVD (stroke and IHD only), as well as CVD mortality, non-CVD mortality and total mortality. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated adjusting for age, sex, behavioral and clinical risk factors and socioeconomic status. Over an average of 12.4 years follow-up, we ascertained 4129 incident CVD events, of which stroke accounted for 1011. Compared to participants with the least DASH-accordant diets, those with the most DASH-accordant diets had 20% lower risk of incident stroke (HR, 95% CI 0.80, 0.65-0.99) and 13% lower risk of total incident CVD (0.88, 0.79-0.99) but no lower risk of CHD (0.90, 0.79-1.02). CVD-related mortality also showed strong inverse associations with DASH accordance (0.72, 0.60-0.85). This study provides evidence for the cardioprotective effects of DASH diet in a UK context

Effects of Foot Position during Squatting on the Quadriceps Femoris: An Electromyographic Study

International Journal of Exercise Science 6(2) : 114-125, 2013. Weightlifters have commonly believed that changing joint position can alter specific muscle activation. The magnitude of force produced by a muscle is highly dependent upon the length of the muscle. The purpose of this study was to determine the effect of foot positioning on muscle activation of the superficial quadriceps as measured by surface electromyography (sEMG) during a functional squatting movement in healthy adults. Twenty physically active asymptomatic adults (7 females and 13 males) were included in the study while four different foot positions (Neutral, Internally Rotated, Externally Rotated, and Staggered) were assessed. Three quadriceps muscles (Rectus Femoris (RF), Vastus Medialis Oblique (VMO), and Vastus Lateralis Oblique(VLO) were measured. Raw EMG was transformed using a root mean square algorithm. Six one-way repeated measure ANOVAs were conducted to examine the peak and average RMS amplitude for each muscle across each condition, with an alpha level of 0.05 set a priori. Across all foot positions only the Staggered foot position reached statistical significance when compared to all other foot positions for each muscle group. Results suggest that altering the foot position during a partial weight squat has little to no effect on the EMG amplitudes of the quadriceps. However, more research is needed to examine the concentric and eccentric phases of the squatting motion separately with the addition of full weight bearing squats

Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

In this investigation, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to study the evolution of deformation in Al13Co4. Streaking of the Laue spots showed that the onset of plastic flow occured at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enabled the geometrically necessary dislocation density to be estimated as 1.1 x 1013 m-2

Relationship between the Romberg Test and the Wii Basic Balance Test and Cognition in Athletes with Concussion

Background: Approximately 30% of individuals with a sport-related concussion present with postural instability. Multiple clinical balance tests exist to diagnose postural instability; yet little is known about the potential relationship between these type of postural assessments and cognition post-concussion. Aim: The purpose of the current study was to assess the relationship between the Romberg test, the Wii Fit basic balance test (WBBT), and the composite scores on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test in a sample of athletes with concussions. Methods: 55 post-concussed athletes (40 male) completed the Romberg Test (RT) (−/+), the WBBT, and ImPACT test. Wii Fit basic balance test performance was operationalized as the number of successfully completed trials (of 5 trials of increasing difficulty) within 30 seconds. Pearson’s and point-biserial correlations examined univariate associations among the variables. Results: The RT and WBBT were not significantly related (r = −0.029, p = 0.832). The RT weakly correlated with ImPACT impairment scores (r= 0.26, p= 0.041), whereas WBBT the number of trials did not (r = − 0.20, p = 0.155). Romberg Test scores were significantly correlated with ImPACT Visual Processing Speed Score (r = 0.27, p = 0.036) and Reaction Time score (r = 0.34, p = 0.006). In contrast, WBBT trials were significantly correlated with the ImPACT Visual Memory Score (r = − 0.41, p = 0.003). Conclusions: These results suggest that the WBBT and RT assess unique aspects of postural control. The RT may relate directly to single sensory cognitive and motor processing, while the WBBT may relate to multi-sensory visually driven cognitive and motor processing. Relevance for patients: Clinical balance tests could point to different cognitive impairments post-concussion

Ground Contact Time Imbalances Strongly Related to Impaired Running Economy

Running economy (RE) is defined as the oxygen consumption (VO2) or caloric unit cost required to move at a specific velocity and is an important performance marker. Ground contact time (GCT) has been associated with RE; however, it has not been established how GCT imbalances between feet impact RE. Purpose: Determine the relationship between cadence, GCT, and GCT imbalances and RE. Methods: 11 NCAA Division I distance runners (7 male) completed a graded exercise test on a treadmill to determine lactate threshold (LT) and VO2max. Body composition was also assessed via DEXA. Subjects ran with a heart rate monitor capable of measuring cadence, GCT, and GCT balance between feet. VO2 and respiratory exchange ratio were recorded over the last minute of the 5-minute stages. RE expressed as caloric unit cost (kcal·kg-1· km-1) was calculated for the stage determined to be just below the LT (prior to \u3e 4mmol/L) and was correlated with cadence, GCT, and GCT imbalance by Pearson correlations. Results: Pearson correlations between RE and the running dynamics measures were as follows: cadence (r = -.444, p = .171), GCT (r = .492, p = .125), GCT Imbalance (r = .808, p \u3c .005). An independent t-test revealed greater (p = .023) leg lean mass imbalances in runners with larger GCT imbalances compared to runners with smaller GCT imbalances. Conclusion: GCT imbalances are strongly related to impaired RE. Future research should determine how to improve GCT imbalances and if doing so improves RE

Collisions of Cosmic F- and D-strings

Recent work suggests that fundamental and Dirichlet strings, and their (p,q) bound states, may be observed as cosmic strings. The evolution of cosmic string networks, and therefore their observational signals, depends on what happens when two strings collide. We study this in string perturbation theory for collisions between all possible pairs of strings; different cases involve sphere, disk, and annulus amplitudes. The result also depends on the details of compactification; the dependence on ratios of scales is only logarithmic, but this is still numerically important. We study a range of models and parameters, and find that in most cases these strings can be distinguished from cosmic strings that arise as gauge theory solitons.Comment: 42 pages, 7 figures; v.2: added references, expanded discussion of reconnection in field theor