17,228 research outputs found
Time-domain Brillouin Scattering as a Local Temperature Probe in Liquids
We present results of time-domain Brillouin scattering (TDBS) to determine
the local temperature of liquids in contact to an optical transducer. TDBS is
based on an ultrafast pump-probe technique to determine the light scattering
frequency shift caused by the propagation of coherent acoustic waves in a
sample. Since the temperature influences the Brillouin scattering frequency
shift, the TDBS signal probes the local temperature of the liquid. Results for
the extracted Brillouin scattering frequencies recorded at different liquid
temperatures and at different laser powers - i.e. different steady state
background temperatures- are shown to demonstrate the usefulness of TDBS as a
temperature probe. This TDBS experimental scheme is a first step towards the
investigation of ultrathin liquids measured by GHz ultrasonic probing.Comment: arXiv admin note: substantial text overlap with arXiv:1702.0107
Resonant pairing between Fermions with unequal masses
We study the pairing between Fermions of different masses, especially at the
unitary limit. At equal populations, the thermodynamic properties are identical
with the equal mass case provided an appropriate rescaling is made. At unequal
populations, for sufficiently light majority species, the system does not phase
separate. For sufficiently heavy majority species, the phase separated normal
phase have a density larger than that of the superfluid. For atoms in harmonic
traps, the density profiles for unequal mass Fermions can be drastically
different from their equal-mass counterparts.Comment: 10 pages, 4 figure
Observation of Phase Separation in a Strongly-Interacting Imbalanced Fermi Gas
We have observed phase separation between the superfluid and the normal
component in a strongly interacting Fermi gas with imbalanced spin populations.
The in situ distribution of the density difference between two trapped spin
components is obtained using phase-contrast imaging and 3D image
reconstruction. A shell structure is clearly identified where the superfluid
region of equal densities is surrounded by a normal gas of unequal densities.
The phase transition induces a dramatic change in the density profiles as
excess fermions are expelled from the superfluid.Comment: 5 pages, 7 figure
A COMPARISON OF ACCURACY AND STROKE CHARACTERISTICS BETWEEN TWO PUTTING GRIP TECHNIQUES
Nowadays PGA golfers are experimenting with various golf putting grips. The purpose of this study was to investigate the traits of using two putting grips; reverse overlapping grip and finger bone grip at three different putting distances. 20 subjects with no previous golf experience participated in this study. The kinematic data of the subject and the putter’s shaft and head was recorded by 8 Qualisys cameras at 100Hz. There was no significant difference between the success rate of getting the ball in the hole at all distances. The finger bone grip produced statistically smaller radial error values than the reverse overlapping grip at the distances for 7 and 11 metres. The finger bone grip provided straighter putter head trajectories and less change in the movement of the COG, which implies more stability of the player and that the ball will travel in the desired path. In conclusion, the finger bone putting technique gave radial errors less than the reverse overlapping grip technique which seems to be due to the added stability and straighter putter head trajectories
Superfluid stability in BEC-BCS crossover
We consider a dilute atomic gas of two species of fermions with unequal
concentrations under a Feshbach resonance. We find that the system can have
distinct properties due to the unbound fermions. The uniform state is stable
only when either (a) beyond a critical coupling strength, where it is a gapless
superfluid, or (b) when the coupling strength is sufficiently weak, where it is
a normal Fermi gas mixture. Phase transition(s) must therefore occur when the
resonance is crossed.Comment: 4 pages, 4 figure
A supermassive binary black hole with triple disks
Hierarchical structure formation inevitably leads to the formation of
supermassive binary black holes (BBHs) with a sub-parsec separation in galactic
nuclei. However, to date there has been no unambiguous detection of such
systems. In an effort to search for potential observational signatures of
supermassive BBHs, we performed high-resolution smoothed particle hydrodynamics
(SPH) simulations of two black holes in a binary of moderate eccentricity
surrounded by a circumbinary disk. Building on our previous work, which has
shown that gas can periodically transfer from the circumbinary disk to the
black holes when the binary is on an eccentric orbit, the current set of
simulations focuses on the formation of the individual accretion disks, their
evolution and mutual interaction, and the predicted radiative signature. The
variation in mass transfer with orbital phase from the circumbinary disk
induces periodic variations in the light curve of the two accretion disks at
ultraviolet wavelengths, but not in the optical or near-infrared. Searches for
this signal offer a promising method to detect supermassive BBHs.Comment: Accepted for publication in the Astrophysical Journal, 16 pages, 11
figures. High Resolution Version is Available at
http://www2.yukawa.kyoto-u.ac.jp/~kimitake/bbhs.htm
MATURATION EFFECTS ON LOWER EXTREMITY KINEMATICS IN A DROP VERTICAL JUMP
As children increase in biologic age, body height and weight increase, and subsequent maturation of the nervous, endocrine, muscular, and cardiovascular systems leads to alterations in neuromuscular performance (Naughton et al., 2000). It is important to understand the effects of growth and development on sports performance and sports injuries. The purpose of this study were to investigate maturation effects on lower extremity kinematics in a drop vertical jump
Parity-violating asymmetry in with a pionless effective theory
Nuclear parity violation is studied with polarized neutrons in the
photodisintegration of the deuteron at low energies. A pionless effective field
theory with di-baryon fields is used for the investigation. Hadronic weak
interactions are treated by parity-violating di-baryon-nucleon-nucleon
vertices, which have undetermined coupling contants. A parity-violating
asymmetry in the process is calculated for the incident photon energy up to 30
MeV. If experimental data for the parity-violating asymmetry become available
in the future, we will be able to determine the unknown coupling contants in
the parity-violating vertices.Comment: 4 pages. A contribution to APFB2011, August 22-26, 2011, Seoul, Kore
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