7,935 research outputs found
Aerobic Energy Expenditure Comparisons Between One Traditional and CrossFit-Based Exercise Session
This study sought to compare aerobic energy expenditure, recovery VO2, peak heart rate, and peak VO2 achieved across 45 min of exercise and 15 min of recovery performing both traditional and CrossFit®-based exercise. Thirty healthy, physically active participants of both genders (15 men, 15 women) performed a workout following the guidelines of the American College of Sports Medicine (traditional) and a workout following the CrossFit® method. Each workout consisted of a 5 min warm-up (light aerobic exercise and stretching), resistance exercise (both focused on leg exercises), cardiorespiratory exercise (a treadmill run for the traditional exercise and circuit training for the CrossFit®-based exercise) and 5 min cool-down (walking). The cool-down was followed by 10 min of sitting to record recovery values. During each workout the participants wore a K4b2 Cosmed unit to measure energy expenditure and VO2, and a Polar heart rate monitor to measure heart rate. Each measure was compared using a Dependent t-Test. Energy expenditure (468 ± 116 vs. 431 ± 96 kcal, p\u3c0.001), peak heart rate (189 ± 8 vs. 172 ± 8 bpm, p\u3c0.001), peak VO2 (3.22 ± 0.73 vs. 2.81 ± 0.63 L/min, p\u3c0.001) and average 15 min recovery VO2 (0.89 ± 0.24 vs. 0.78 ± 0.18 L/min, p\u3c0.001) were significantly greater in the CrossFit®-based workout. The present study suggests that CrossFit®-based exercise may result in greater aerobic energy expenditure than traditional exercise
Equivalences between spin models induced by defects
The spectrum of integrable spin chains are shown to be independent of the
ordering of their spins. As an application we introduce defects (local spin
inhomogeneities in homogenous chains) in two-boundary spin systems and, by
changing their locations, we show the spectral equivalence of different
boundary conditions. In particular we relate certain nondiagonal boundary
conditions to diagonal ones.Comment: 14 pages, 16 figures, LaTeX, Extended versio
Structure of the two-boundary XXZ model with non-diagonal boundary terms
We study the integrable XXZ model with general non-diagonal boundary terms at
both ends. The Hamiltonian is considered in terms of a two boundary extension
of the Temperley-Lieb algebra.
We use a basis that diagonalizes a conserved charge in the one-boundary case.
The action of the second boundary generator on this space is computed. For the
L-site chain and generic values of the parameters we have an irreducible space
of dimension 2^L. However at certain critical points there exists a smaller
irreducible subspace that is invariant under the action of all the bulk and
boundary generators. These are precisely the points at which Bethe Ansatz
equations have been formulated. We compute the dimension of the invariant
subspace at each critical point and show that it agrees with the splitting of
eigenvalues, found numerically, between the two Bethe Ansatz equations.Comment: 9 pages Latex. Minor correction
Outer jet X-ray and radio emission in R Aquarii: 1999.8 to 2004.0
Chandra and VLA observations of the symbiotic star R Aqr in 2004 reveal
significant changes over the three to four year interval between these
observations and previous observations taken with the VLA in 1999 and with
Chandra in 2000. This paper reports on the evolution of the outer thermal X-ray
lobe-jets and radio jets. The emission from the outer X-ray lobe-jets lies
farther away from the central binary than the outer radio jets, and comes from
material interpreted as being shock heated to ~10^6 K, a likely result of
collision between high speed material ejected from the central binary and
regions of enhanced gas density. Between 2000 and 2004, the Northeast (NE)
outer X-ray lobe-jet moved out away from the central binary, with an apparent
projected motion of ~580 km s^-1. The Southwest (SW) outer X-ray lobe-jet
almost disappeared between 2000 and 2004, presumably due to adiabatic expansion
and cooling. The NE radio bright spot also moved away from the central binary
between 2000 and 2004, but with a smaller apparent velocity than of the NE
X-ray bright spot. The SW outer lobe-jet was not detected in the radio in
either 1999 or 2004. The density and mass of the X-ray emitting material is
estimated. Cooling times, shock speeds, pressure and confinement are discussed.Comment: 23 pages, 8 figure
SlipChip for immunoassays in nanoliter volumes
This article describes a SlipChip-based approach to
perform bead-based heterogeneous immunoassays with
multiple nanoliter-volume samples. As a potential device
to analyze the output of the chemistrode, the performance
of this platform was tested using low concentrations of
biomolecules. Two strategies to perform the immunoassay
in the SlipChip were tested: (1) a unidirectional slipping
method to combine the well containing a sample with a
series of wells preloaded with reagents and (2) a back-and-forth slipping method to introduce a series of reagents
to a well containing the sample by reloading and slipping
the well containing the reagent. The SlipChips were
fabricated with hydrophilic surfaces on the interior of the
wells and with hydrophobic surfaces on the face of the
SlipChip to enhance filling, transferring, and maintaining
aqueous solutions in shallow wells. Nanopatterning was
used to increase the hydrophobic nature of the SlipChip
surface. Magnetic beads containing the capture antibody
were efficiently transferred between wells and washed by
serial dilution. An insulin immunoenzymatic assay showed
a detection of limit of ∼13 pM. A total of 48 droplets of
nanoliter volume were analyzed in parallel, including an
on-chip calibration. The design of the SlipChip is flexible
to accommodate other types of immunoassays, both
heterogeneous and homogeneous. This work establishes
the possibility of using SlipChip-based immunoassays in
small volumes for a range of possible applications, including analysis of plugs from a chemistrode, detection of
molecules from single cells, and diagnostic monitoring
X-Atlas: An Online Archive of Chandra's Stellar High Energy Transmission Gratings Observations
The high-resolution X-ray spectroscopy made possible by the 1999 deployment
of the Chandra X-ray Observatory has revolutionized our understanding of
stellar X-ray emission. Many puzzles remain, though, particularly regarding the
mechanisms of X-ray emission from OB stars. Although numerous individual stars
have been observed in high-resolution, realizing the full scientific potential
of these observations will necessitate studying the high-resolution Chandra
dataset as a whole. To facilitate the rapid comparison and characterization of
stellar spectra, we have compiled a uniformly processed database of all stars
observed with the Chandra High Energy Transmission Grating (HETG). This
database, known as X-Atlas, is accessible through a web interface with
searching, data retrieval, and interactive plotting capabilities. For each
target, X-Atlas also features predictions of the low-resolution ACIS spectra
convolved from the HETG data for comparison with stellar sources in archival
ACIS images. Preliminary analyses of the hardness ratios, quantiles, and
spectral fits derived from the predicted ACIS spectra reveal systematic
differences between the high-mass and low-mass stars in the atlas and offer
evidence for at least two distinct classes of high-mass stars. A high degree of
X-ray variability is also seen in both high and low-mass stars, including
Capella, long thought to exhibit minimal variability. X-Atlas contains over 130
observations of approximately 25 high-mass stars and 40 low-mass stars and will
be updated as additional stellar HETG observations become public. The atlas has
recently expanded to non-stellar point sources, and Low Energy Transmission
Grating (LETG) observations are currently being added as well
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