32,379 research outputs found
Barefoot running improves economy at high intensities and peak treadmill velocity
Aim: Barefoot running can improve running economy (RE) compared to shod running at low exercise intensities, but data is lacking for the higher intensities typical during many distance running competitions. The influence of barefoot running on the velocity at maximal oxygen uptake (vVO2max) and peak incremental treadmill test velocity (vmax) is unknown. The present study tested the hypotheses that barefoot running would improve RE, vVO2max and vmax relative to shod running.
Methods: Using a balanced within-subject repeated measures design, eight male runners (aged 23.1±4.5 years, height 1.80±0.06 m, mass 73.8±11.5 kg, VO2max 4.08±0.39 L·min-1) completed a familiarization followed by one barefoot and one shod treadmill running trial, 2-14 days apart. Trial sessions consisted of a 5 minute warm-up, 5 minute rest, followed by 4×4 minute stages, at speeds corresponding to ~67, 75, 84 and 91% shod VO2max respectively, separated by a 1 minute rest. After the 4th stage treadmill speed was incremented by 0.1 km·h-1 every 15 s until participants reached volitional exhaustion.
Results: RE was improved by 4.4±7.0% across intensities in the barefoot condition (P=0.040). The improvement in RE was related to removed shoe mass (r2=0.80, P=0.003) with an intercept at 0% improvement for RE at 0.520 kg total shoe mass. Both vVO2max (by 4.5±5.0%, P=0.048) and vmax (by 3.9±4.0%, P=0.030) also improved but VO2max was unchanged (p=0.747).
Conclusion: Barefoot running improves RE at high exercise intensities and increases vVO2max and vmax, but further research is required to clarify the influence of very light shoe weights on RE
Measuring the Hidden Aspects of Solar Magnetism
2008 marks the 100th anniversary of the discovery of astrophysical magnetic
fields, when George Ellery Hale recorded the Zeeman splitting of spectral lines
in sunspots. With the introduction of Babcock's photoelectric magnetograph it
soon became clear that the Sun's magnetic field outside sunspots is extremely
structured. The field strengths that were measured were found to get larger
when the spatial resolution was improved. It was therefore necessary to come up
with methods to go beyond the spatial resolution limit and diagnose the
intrinsic magnetic-field properties without dependence on the quality of the
telescope used. The line-ratio technique that was developed in the early 1970s
revealed a picture where most flux that we see in magnetograms originates in
highly bundled, kG fields with a tiny volume filling factor. This led to
interpretations in terms of discrete, strong-field magnetic flux tubes embedded
in a rather field-free medium, and a whole industry of flux tube models at
increasing levels of sophistication. This magnetic-field paradigm has now been
shattered with the advent of high-precision imaging polarimeters that allow us
to apply the so-called "Second Solar Spectrum" to diagnose aspects of solar
magnetism that have been hidden to Zeeman diagnostics. It is found that the
bulk of the photospheric volume is seething with intermediately strong, tangled
fields. In the new paradigm the field behaves like a fractal with a high degree
of self-similarity, spanning about 8 orders of magnitude in scale size, down to
scales of order 10 m.Comment: To appear in "Magnetic Coupling between the Interior and the
Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and
Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 200
Universality classes and crossover behaviors in non-Abelian directed sandpiles
We study universality classes and crossover behaviors in non-Abelian directed
sandpile models, in terms of the metastable pattern analysis. The non-Abelian
property induces spatially correlated metastable patterns, characterized by the
algebraic decay of the grain density along the propagation direction of an
avalanche. Crossover scaling behaviors are observed in the grain density due to
the interplay between the toppling randomness and the parity of the threshold
value. In the presence of such crossovers, we show that the broadness of the
grain distribution plays a crucial role in resolving the ambiguity of the
universality class. Finally, we claim that the metastable pattern analysis is
important as much as the conventional analysis of avalanche dynamics.Comment: 10 pages, 7 figures, 1 table; published in PRE as the full paper of
PRL v101, 218001 (2008
Three-loop HTL gluon thermodynamics at intermediate coupling
We calculate the thermodynamic functions of pure-glue QCD to three-loop order
using the hard-thermal-loop perturbation theory (HTLpt) reorganization of
finite temperature quantum field theory. We show that at three-loop order
hard-thermal-loop perturbation theory is compatible with lattice results for
the pressure, energy density, and entropy down to temperatures .
Our results suggest that HTLpt provides a systematic framework that can used to
calculate static and dynamic quantities for temperatures relevant at LHC.Comment: 24 pages, 13 figs. 2nd version: improved discussion and fixing typos.
Published in JHE
The physiological expression of inducible nitric oxide synthase (iNOS) in the human colon
Inducible nitric oxide synthase (iNOS) is expressed in the colonic epithelium in both inflammatory bowel disease and colorectal cancer. Nitric oxide (NO), the product of this enzyme, has been implicated in the pathogenesis of both conditions. However, there are conflicting data on whether iNOS is expressed in the normal, uninflamed human colon. To evaluate the expression of iNOS in histologically normal, non-inflamed human colonic mucosa. Reverse transcription polymerase chain reaction (RT-PCR), immunoblotting, and immunohistochemistry were used to investigate the expression of iNOS in 17 histologically normal specimens obtained at colectomy performed for colorectal neoplasia. In addition, 16 endoscopic mucosal biopsies, taken from normal individuals, were also evaluated. Eleven surgical specimens and 16 endoscopic biopsies from patients with refractory ulcerative colitis were used as inflammatory controls. All types of specimens expressed iNOS mRNA. Immunoblotting revealed a protein of approximately 130 kDa consistent with iNOS in mucosal extracts of 77% of normal individuals, and 85% of diseased controls. Immunolabelling localised this protein to the surface epithelium in most of the normal specimens and also to the crypt epithelium and inflammatory cells in the diseased controls. These findings provide evidence that iNOS is often expressed in the surface epithelium of non-inflamed human colon, suggesting that it is induced by local luminal factors, such as bacterial lipopolysaccharide (endotoxin). The resultant NO produced at this site might act as an oxidative barrier, reducing bacterial translocation and providing a means of defence against pathogenic microorganisms
Southern Families and Their Daughters: The Self and the System in Selected Texts by Grau, Gilchrist, Welty, Spencer, and Douglas.
In this interdisciplinary study, I apply the materials of family systems theory to the study of five twentieth-century literary texts, each written by a Southern white woman. Arranged in the order they will appear in this study, the five texts are The Keepers of the House (1964) by Shirley Ann Grau; Net of Jewels (1992) by Ellen Gilchrist; The Golden Apples (1949) by Eudora Welty; The Voice at the Back Door (1956) by Elizabeth Spencer; and Can\u27t Quit You, Baby (1988) by Ellen Douglas. In the analysis of these books--all examples of domestic and social realism--I analyze and measure the effects of the family system on the individuation process of each female protagonist, particularly (as the texts are arranged) the increasing degrees of differentiation that the female protagonist achieves as she conforms to or resists the family and cultural forms she faces. A second purpose is to explore and evaluate the potential of family systems theory as a reliable tool for the analysis of imaginative fiction in general and these texts by these Southern women writers in particular. These results indicate that both the specific family structure and the communication processes of each of the five families supported and fostered the traditional Southern roles of Southern belle and lady. Each of the protagonists also found these roles restrictive, yet how each one reacted to these roles was a measure of her family\u27s particular destructive qualities and her unique temperament. From family to family, the central problem varied. Abigail Howland faced neglect and abandonment; Rhoda Manning endured a patriarchal, controlling father; Virgie Rainey experienced the diminished presence of a mother who loved an outsider; Marcia Mae grew up amid secrets and forbidden speech topics; and Cornelia also faced lies and family secrets. Each protagonist, facing various difficulties, employed strategies that were designed to distinguish and differentiate her from the family. They met with varying degrees of success, in their efforts to overcome family difficulties and to integrate the desire for individuality with the demands of family and community
Interaction-induced Interlayer Charge Transfer in the Extreme Quantum Limit
An interacting bilayer electron system provides an extended platform to study
electron-electron interaction beyond single layers. We report here experiments
demonstrating that the layer densities of an asymmetric bilayer electron system
oscillate as a function of perpendicular magnetic field that quantizes the
energy levels. At intermediate fields, this interlayer charge transfer can be
well explained by the alignment of the Landau levels in the two layers. At the
highest fields where both layers reach the extreme quantum limit, however,
there is an anomalous, enhanced charge transfer to the majority layer.
Surprisingly, when the minority layer becomes extremely dilute, this charge
transfer slows down as the electrons in the minority layer condense into a
Wigner crystal. Furthermore, by examining the quantum capacitance of the dilute
layer at high fields, the screening induced by the composite fermions in an
adjacent layer is unveiled. The results highlight the influence of strong
interaction in interlayer charge transfer in the regime of very high fields and
low Landau level filling factors.Comment: Please see the formal version on PR
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