3,173 research outputs found
Relationship Between Mechanical And Physiological Energy Costs And Efficiency Of Treadmill Walking In Active And Inactive Females
Energy costs of walking are traditionally examined from two perspectives biomechanical and physiological. Biomechanists use mechanical energy costs to calculate mechanical work (MW) performed by the body. Physiologists use energy expenditure to calculate metabolic cost (MC) of the activity. These two values are then used to calculate efficiency values for walking. However, few researchers have examined the rela tionship between these two forms of energy cost (MW and MC) and the calculated efficiency value (EFF). The purpose of this study was to examine the relationship between MW and MC, MW and EFF, and MC and EFF during treadmill walking in active (ACT) and inactive (INCT) females. It was hypothesized that a high correlation would exist between MW and MC because the amount of work done by the segments would be dependent on the amount of energy expended by the muscles for muscle contraction to move the segments. Two groups (ACT and INCT) of 12 females participated in a 10-min submax walking test. Submax V02 and 3D film records (100 fps) were obtained during the final minute of the test. MW, MC, and EFF were calculated using the method recommended by Cavanagh and Williams (1983). Correlations for each group were calculated between MW and MC (ACT: r= .340; INCT: r= .429), MC and EFF (ACT: r= -.271; INCT: r = -.149), and MW and EFF (ACT: r= .854; INCT: r= .817). Significant correlations were found between MW and EFF for both groups (p f. .01). No relationship was found between MW and MC for either group.
Biomechanists have attempted to adjust MW by developing methods for approximating the amount of mechanical energy conserved by energy transfer within and between segments, by the storage of elastic energy, and by the performance of negative work as opposed to positive work. This leads to a more accurate representation of mechanical energy cost related
Precision Flavour Physics with and
We show that a combined analysis of and
allows for new physics tests practically free of form factor uncertainties.
Residual theory errors are at the level of several percent. Our study
underlines the excellent motivation for measuring these modes at a Super
Flavour Factory.Comment: 26 pages, 2 figure
Probing New Physics via an Angular Analysis of B --> V1 V2 decays
We show that an angular analysis of B --> V1 V2 decays yields numerous tests
for new physics in the decay amplitudes. Unlike direct CP asymmetries, many of
these new-physics observables are nonzero even if the strong phase differences
vanish. For certain observables, neither time-dependent measurements nor
tagging is necessary. Should a signal for new physics be found, one can place a
lower limit on the size of the new-physics parameters, as well as on their
effect on the measurement of the phase of B0--Bbar0 mixing.Comment: 9 pages, plain latex, no figures. Title modified slightly. Paragraph
added about viability of method. Conclusions unchanged. To be published in
Europhysics Letter
Variability in supply and cross-shelf transport of pink shrimp (Farfantepenaeus duorarum) postlarvae into western Florida Bay
The variability in the supply of pink shrimp (Farfantepenaeus duorarum) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation
results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp
R-parity-violating SUSY and CP violation in B --> phi K_s
Recent measurements of CP asymmetry in B --> phi K_S appear to be
inconsistent with Standard Model expectations. We explore the effect of
R-parity-violating SUSY to understand the data.Comment: Equations corrected. Conclusions unchanged. Latex, 6 pages, one fi
High-Dimensional Stochastic Design Optimization by Adaptive-Sparse Polynomial Dimensional Decomposition
This paper presents a novel adaptive-sparse polynomial dimensional
decomposition (PDD) method for stochastic design optimization of complex
systems. The method entails an adaptive-sparse PDD approximation of a
high-dimensional stochastic response for statistical moment and reliability
analyses; a novel integration of the adaptive-sparse PDD approximation and
score functions for estimating the first-order design sensitivities of the
statistical moments and failure probability; and standard gradient-based
optimization algorithms. New analytical formulae are presented for the design
sensitivities that are simultaneously determined along with the moments or the
failure probability. Numerical results stemming from mathematical functions
indicate that the new method provides more computationally efficient design
solutions than the existing methods. Finally, stochastic shape optimization of
a jet engine bracket with 79 variables was performed, demonstrating the power
of the new method to tackle practical engineering problems.Comment: 18 pages, 2 figures, to appear in Sparse Grids and
Applications--Stuttgart 2014, Lecture Notes in Computational Science and
Engineering 109, edited by J. Garcke and D. Pfl\"{u}ger, Springer
International Publishing, 201
A study of semi-inclusive charmless decays
We study semi-inclusive charmless decays in detail, such as
, , , where does not contain a charm (anti)quark. We find that
the process () can be particularly
useful for determination of the CKM matrix element . We calculate and
present the branching ratio (BR) of as a function of
, with an estimate of possible uncertainties. It is expected that the
BR is an order of . Our estimation indicates that one can
phenomenologically determine with reasonable accuracy by measuring
the BR of ().Comment: 18 pages, 7 figures; Revtex; version accepted for publication in Eur.
Phys. J.
Right-handed currents in rare exclusive B -> (K, K*) nu bar{nu} decays
The effects of possible right-handed weak hadronic currents in rare exclusive
semileptonic decays B -> (K, K*) nu bar{nu} are investigated using a
lattice-constrained dispersion quark model for the calculation of the relevant
mesonic form factors. The results obtained for the branching ratios and the
missing energy spectra are presented and the sensitivity of various observables
to long-distance physics is investigated. It is shown that the asymmetry of
transversely polarized K*(T) mesons as well as the K / K*(T) production ratio
are only slightly sensitive to long-distance contributions and mostly governed
by the relative strength and phase of right-handed currents. In particular,
within the Standard Model the production of right-handed K*(T) mesons turns out
to be largely suppressed with respect to left-handed ones, thanks to the
smallness of the final to initial meson mass ratio. Therefore, the measurement
of produced right-handed K*(T) mesons in rare B -> K* nu bar{nu} decays offers
a very interesting tool to investigate right-handed weak hadronic currents.Comment: latex, 10 pp., 4 figures with epsfig.st
Enhanced CP Violation with Modes and Extraction of the CKM Angle gamma
The Gronau-London-Wyler (GLW) method extracts the CKM angle by
measuring decay rates involving mesons. Since that
method necessitates the interference between two amplitudes that are
significantly different in magnitude, the resulting asymmetries tend to be
small. CP violation can be greatly enhanced for decays to final states that are
common to both D^0 and and that are not CP eigenstates. In
particular, large asymmetries are possible for final states f such that is doubly Cabibbo suppressed while is Cabibbo allowed.
The measurement of interference effects in two such modes allows the extraction
of without prior knowledge of , which
may be difficult to determine due to backgrounds.Comment: 12 pages, LaTeX, no figure
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