Role of fourth-order phase-space moments in collective modes of trapped Fermi gases

We study the transition from hydrodynamic to collisionless behavior in collective modes of ultracold trapped Fermi gases. To that end, we solve the Boltzmann equation for the trapped Fermi gas via the moments method. We showed previously that it is necessary to go beyond second-order moments if one wants to reproduce the results of a numerical solution of the Boltzmann equation. Here, we will give the detailed description of the method including fourth-order moments. We apply this method to the case of realistic parameters, and compare the results for the radial quadrupole and scissors modes at unitarity to experimental data obtained by the Innsbruck group. It turns out that the inclusion of fourth-order moments clearly improves the agreement with the experimental data. In particular, the fourth-order moments reduce the effect of collisions and therefore partially compensate the effect of the enhanced in-medium cross section at low temperatures.Comment: 10 pages, 2 figures; published versio

Age-related changes in 100-km ultra-marathon running performance

The aims of this study were (1) to investigate the participation and performance trends at the ‘100km Lauf Biel' in Switzerland from 1998 to 2010, and (2) to compare the age-related changes in 100-km running performance between males and females. For both sexes, the percent of finishers significantly (P < 0.01) decreased for the 18-29 and the 30-39-year age groups, while it significantly (P < 0.01) increased for the 40-49 and the 50-59-year age groups over the studied period. From 1998 to 2010, the mean age of the top ten finishers increased by 0.4years per annum for both females (P = 0.02) and males (P = 0.003). The running time for the top ten finishers remained stable for females, while it significantly (P = 0.001) increased by 2.4min per annum for males. There was a significant (P < 0.001) age effect on running times for both sexes. The best 100-km running times was observed for the age comprised between 30 and 49years for males, and between 30 and 54years for females, respectively. The age-related decline in running performance was similar until 60-64years between males and females, but was greater for females compared to males after 65years. Future studies should investigate the lifespan from 65 to 75years to better understand the performance difference between male and female master ultra-marathoner

Numerical solution of the Boltzmann equation for the collective modes of trapped Fermi gases

We numerically solve the Boltzmann equation for trapped fermions in the normal phase using the test-particle method. After discussing a couple of tests in order to estimate the reliability of the method, we apply it to the description of collective modes in a spherical harmonic trap. The numerical results are compared with those obtained previously by taking moments of the Boltzmann equation. We find that the general shape of the response function is very similar in both methods, but the relaxation time obtained from the simulation is significantly longer than that predicted by the method of moments. It is shown that the result of the method of moments can be corrected by including fourth-order moments in addition to the usual second-order ones and that this method agrees very well with our numerical simulations.Comment: 13 pages, 8 figures, accepted for publication in Phys. Rev.

The effects of course length on freestyle swimming speed in elite female and male swimmers - a comparison of swimmers at national and international level

Freestyle swimming performance over 50 m, 100 m, 200 m, 400 m, 800 m and 1,500 m was compared on short (25 m) and long (50 m) course for 92,196 national swimmers (i.e. annual high score list Switzerland) and 1,104 international swimmers (i.e. finalists FINA World Championships) from 2000 to 2012. National and international swimmers of both sexes were on average 2.0 ± 0.6% faster on short than on long course. Sex-related differences in swimming speed were greater on short than on long course for international and national swimmers from 50 m to 800 m. Freestyle swimming performance improved across years for international swimmers in both short- and long-course whereas only male national swimmers were able to improve on short and long course events except for short course events on 800 m and 1,500 m. Performance in national women competing in short and long course events showed only improvements on 50 m, 100 m and 1,500 m across years. The sex-related differences in freestyle swimming performance showed no change for international swimmers. For national swimmers, the sex-related differences in freestyle swimming performance increased over time in long course from 50 m to 800 m, but decreased for 1,500 m. In conclusion, elite female and male freestyle swimmers at national and international level were about 2% faster on 25 m compared to 50 m course. During the 2000-2012 period, international as well as national swimmers (i.e. for national level predominantly men) improved freestyle swimming performance in both long and short course. More vigorous and optimized training programs focused on muscular force production in combination with efficient swimming skills might close the performance gap between elite swimmers at national level and FINA finalists. Further research especially including effects of anthropometric, biomechanical, and physiological factors is required to fully understand the effects of course length on freestyle swimming performance, and to determine whether course length has similar effects on other swim styles

Elite triathletes in ‘Ironman Hawaii' get older but faster

The age of peak performance has been well investigated for elite athletes in endurance events such as marathon running, but not for ultra-endurance (>6h) events such as an Ironman triathlon covering 3.8km swimming, 180km cycling and 42km running. The aim of this study was to analyze the changes in the age and performances of the annual top ten women and men at the Ironman World Championship the ‘Ironman Hawaii' from 1983 to 2012. Age and performances of the annual top ten women and men in overall race time and in each split discipline were analyzed. The age of the annual top ten finishers increased over time from 26 ± 5 to 35 ± 5years (r 2 = 0.35, P < 0.01) for women and from 27 ± 2 to 34 ± 3years (r 2 = 0.28, P < 0.01) for men. Overall race time of the annual top ten finishers decreased across years from 671 ± 16 to 566 ± 8min (r 2 = 0.44, P < 0.01) for women and from 583 ± 24 to 509 ± 6min (r 2 = 0.41, P < 0.01) for men. To conclude, the age of annual top ten female and male triathletes in the ‘Ironman Hawaii' increased over the last three decades while their performances improved. These findings suggest that the maturity of elite long-distance triathletes has changed during this period and raises the question of the upper limits of the age of peak performance in elite ultra-endurance performance

Age of peak swim speed and sex difference in performance in medley and freestyle swimming – A comparison between 200 m and 400 m in Swiss elite swimmers

The aims of the present study were to examine (i) the age of peak swim speed and (ii) the sex difference in peak swim times in 200m and 400m medley versus freestyle. Swim times and ages of 5,524 swimmers (2,785 males and 2,739 females) from the Swiss high score list from 2006 to 2010 were analyzed using one-way analysis of variance (ANOVA). The age of peak swim speed was younger for females (~20-21 years) compared to males (~22-25 years) for both distances and both swimming styles. The sex differences in peak swim times for age group 10-39 years were 9.7% (SD=3.4) and 7.1% (SD=5.1) for 200m and 400m individual medley, and 10.1% (SD=5.0) and 6.1% (SD=4.0) for 200m and 400m freestyle, respectively. The sex differences were neither different between the two distances nor between the two disciplines (p > .05). There were no differences within each sex (i.e. females to females, and males to males) in the age of reaching peak swim speed in 200m and 400m individual medley and freestyle. However, females reached the peak swim speed at a younger age than males. The sex differences in peak swim times were similar for 200m than for 400m for both swim styles. To summarize, the present findings suggest no difference in the age of peak swim times in 200m and 400m individual medley and freestyle. However, females reached peak swim times earlier than males, which might be dependent on a different development of the genders in puberty and the related physiological and anthropometric factors. Sex differences in peak swim times were similar for 200m than for 400m for both swim styles

Participation and Performance Trends in Triple Iron Ultra-triathlon - a Cross-sectional and Longitudinal Data Analysis

PURPOSE: The aims of the present study were to investigate (i) the changes in participation and performance and (ii) the gender difference in Triple Iron ultra-triathlon (11.4 km swimming, 540 km cycling and 126.6 km running) across years from 1988 to 2011. METHODS: For the cross-sectional data analysis, the association between with overall race times and split times was investigated using simple linear regression analyses and analysis of variance. For the longitudinal data analysis, the changes in race times for the five men and women with the highest number of participations were analysed using simple linear regression analyses. RESULTS: During the studied period, the number of finishers were 824 (71.4%) for men and 80 (78.4%) for women. Participation increased for men (r(2)=0.27, P<0.01) while it remained stable for women (8%). Total race times were 2,146 ± 127.3 min for men and 2,615 ± 327.2 min for women (P<0.001). Total race time decreased for men (r(2)=0.17; P=0.043), while it increased for women (r(2)=0.49; P=0.001) across years. The gender difference in overall race time for winners increased from 10% in 1992 to 42% in 2011 (r(2)=0.63; P<0.001). The longitudinal analysis of the five women and five men with the highest number of participations showed that performance decreased in one female (r(2)=0.45; P=0.01). The four other women as well as all five men showed no change in overall race times across years. CONCLUSIONS: Participation increased and performance improved for male Triple Iron ultra-triathletes while participation remained unchanged and performance decreased for females between 1988 and 2011. The reasons for the increase of the gap between female and male Triple Iron ultra-triathletes need further investigations

The assessment of neuromuscular fatigue during 120 min of simulated soccer exercise

Purpose This investigation examined the development of neuromuscular fatigue during a simulated soccer match incorporating a period of extra time (ET) and the reliability of these responses on repeated test occasions. Methods Ten male amateur football players completed a 120 min soccer match simulation (SMS). Before, at half time (HT), full time (FT), and following a period of ET, twitch responses to supramaximal femoral nerve and transcranial magnetic stimulation (TMS) were obtained from the knee-extensors to measure neuromuscular fatigue. Within 7 days of the first SMS, a second 120 min SMS was performed by eight of the original ten participants to assess the reliability of the fatigue response. Results At HT, FT, and ET, reductions in maximal voluntary force (MVC; −11, −20 and −27%, respectively, P ≤ 0.01), potentiated twitch force (−15, −23 and −23%, respectively, P < 0.05), voluntary activation (FT, −15 and ET, −18%, P ≤ 0.01), and voluntary activation measured with TMS (−11, −15 and −17%, respectively, P ≤ 0.01) were evident. The fatigue response was robust across both trials; the change in MVC at each time point demonstrated a good level of reliability (CV range 6–11%; ICC2,1 0.83–0.94), whilst the responses identified with motor nerve stimulation showed a moderate level of reliability (CV range 5–18%; ICC2,1 0.63–0.89) and the data obtained with motor cortex stimulation showed an excellent level of reliability (CV range 3–6%; ICC2,1 0.90–0.98). Conclusion Simulated soccer exercise induces a significant level of fatigue, which is consistent on repeat tests, and involves both central and peripheral mechanisms

Effectiveness of Protected Areas in Maintaining Plant Production

Given the central importance of protected area systems in local, regional and global conservation strategies, it is vital that there is a good understanding of their effectiveness in maintaining ecological functioning. Here, we provide, to our knowledge, the first such global analysis, focusing on plant production, a “supporting” ecosystem function necessary for multiple other ecosystem services. We use data on the normalized difference vegetation index (NDVI) as a measure of variation in plant production in the core, boundary and surroundings of more than 1000 large protected areas over a 25 year period. Forested protected areas were higher (or similar), and those non-forested were lower (or similar), in NDVI than their surrounding areas, and these differences have been sustained. The differences from surrounding areas have increased for evergreen broadleaf forests and barren grounds, decreased for grasslands, and remained similar for deciduous forests, woodlands, and shrublands, reflecting different pressures on those surroundings. These results are consistent with protected areas being effective both in the representation and maintenance of plant production. However, widespread overall increases in NDVI during the study period suggest that plant production within the core of non-forested protected areas has become higher than it was in the surroundings of those areas in 1982, highlighting that whilst the distinctiveness of protected areas from their surroundings has persisted the nature of that difference has changed