293,794 research outputs found
Interaction of gravitational waves with an elastic solid medium
Contents. 1. Introduction. 2. Kinematics of a Material Medium: Material
Representation. 3. Kinematics of a Material Medium: Convected Differentials. 4.
Kinematics of a Perfect Elastic Medium. 5. Small Gravitational Perturbations of
an Elastic Medium.Comment: 14 pages TeX file of contrib. to proc. Gravitational Radiation, Les
Houches 1982, ed N. Deruelle, T. Piran, 455-464 (North Holland, Amsterdam,
1983
An Analytic Result for the Two-Loop Hexagon Wilson Loop in N = 4 SYM
In the planar N=4 supersymmetric Yang-Mills theory, the conformal symmetry
constrains multi-loop n-edged Wilson loops to be basically given in terms of
the one-loop n-edged Wilson loop, augmented, for n greater than 6, by a
function of conformally invariant cross ratios. We identify a class of
kinematics for which the Wilson loop exhibits exact Regge factorisation and
which leave invariant the analytic form of the multi-loop n-edged Wilson loop.
In those kinematics, the analytic result for the Wilson loop is the same as in
general kinematics, although the computation is remarkably simplified with
respect to general kinematics. Using the simplest of those kinematics, we have
performed the first analytic computation of the two-loop six-edged Wilson loop
in general kinematics.Comment: 17 pages. Extended discussion on how the QMRK limit is taken. Version
accepted by JHEP. A text file containing the Mathematica code with the
analytic expression for the 6-point remainder function is include
A preliminary investigation of trunk and wrist kinematics when using drivers with different shaft properties
It is unknown whether skilled golfers will modify their kinematics when using drivers of different shaft properties. This study aimed to firstly, determine if golf swing kinematics and swing parameters and related launch conditions differed when using modified drivers, then secondly, determine which kinematics were associated with clubhead speed. Twenty high level amateur male golfers (Mean ± SD: handicap = 1.9 ± 1.9 score) had their three-dimensional trunk and wrist kinematics collected for two driver trials. Swing parameters and related launch conditions were collected using a launch monitor. A one-way repeated measures ANOVA revealed significant (p ≤ 0.003) between-driver differences; specifically, faster trunk axial rotation velocity and an early wrist release for the low kick point driver. Launch angle was shown to be 2° lower for the high kick point driver. Regression models for both drivers explained a significant amount of variance (60 – 67%) in clubhead speed. Wrist kinematics were most associated with clubhead speed, indicating the importance of the wrists in producing clubhead speed regardless of driver shaft properties
Baryon Magnetic Moments in Relativistic Quark Models
It is shown that the phenomenological description of the baryon magnetic
moments in the quark model carries over to the Poincar\'e covariant extension
of the model. This applies to all the three common forms of relativistic
kinematics with structureless constituent currents, which are covariant under
the corresponding kinematic subgroups. In instant and front form kinematics the
calculated magnetic moments depend strongly on the constituent masses, while in
point form kinematics the magnetic moments are fairly insensitive to both the
quark masses and the wave function model. The baryon charge radii and magnetic
moments are determined in the different forms of kinematics for the
light-flavor, strange and charm hyperons. The wave function model is determined
by a fit to the electromagnetic form factor of the proton.Comment: Six references and one paragraph adde
Kinematics of Clustering
The dynamical system for inertial particles in fluid flow has both attracting
and repelling regions, the interplay of which can localize particles. In
laminar flow experiments we find that particles, initially moving throughout
the fluid domain, can undergo an instability and cluster into subdomains of the
fluid when the flow Reynolds number exceeds a critical value that depends on
particle and fluid inertia. We derive an expression for the instability
boundary and for a universal curve that describes the clustering rate for all
particles.Comment: 13 pages, 6 figure
Internal kinematics of spiral galaxies in distant clusters IV. Gas kinematics of spiral galaxies in intermediate redshift clusters and in the field
(Abridged) We trace the interaction processes of galaxies at intermediate
redshift by measuring the irregularity of their ionized gas kinematics, and
investigate these irregularities as a function of the environment (cluster
versus field) and of morphological type (spiral versus irregular). Our sample
consists of 92 distant galaxies. 16 cluster (z~0.3 and z~0.5) and 29 field
galaxies (mean z=0.44) of these have velocity fields with sufficient signal to
be analyzed. We find that the fraction of galaxies that have irregular gas
kinematics is remarkably similar in galaxy clusters and in the field at
intermediate redshifts. The distribution of the field and cluster galaxies in
(ir)regularity parameters space is also similar. On the other hand galaxies
with small central concentration of light, that we see in the field sample, are
absent in the cluster sample. We find that field galaxies at intermediate
redshifts have more irregular velocity fields as well as more clumpy and less
centrally concentrated light distributions than their local counterparts.
Comparison with a SINS sample of 11 z ~ 2 galaxies shows that these distant
galaxies have more irregular gas kinematics than our intermediate redshift
cluster and field sample. We do not find a dependence of the irregularities in
gas kinematics on morphological type. We find that two different indicators of
star formation correlate with irregularity in the gas kinematics. More
irregular gas kinematics, also more clumpy and less centrally concentrated
light distributions of spiral field galaxies at intermediate redshifts in
comparison to their local counterparts indicate that these galaxies are
probably still in the process of building their disks via mechanisms such as
accretion and mergers. On the other hand, they have less irregular gas
kinematics compared to galaxies at z ~ 2.Comment: Accepted for publication in A&A, high resolution version available at
http://www.astro.rug.nl/~kutdemir/13262/13262_hr.p
Galactic outflows and the kinematics of damped Lyman alpha absorbers
The kinematics of damped Lyman alpha absorbers (DLAs) are difficult to
reproduce in hierarchical galaxy formation models, particularly the
preponderance of wide systems. We investigate DLA kinematics at z=3 using
high-resolution cosmological hydrodynamical simulations that include a
heuristic model for galactic outflows. Without outflows, our simulations fail
to yield enough wide DLAs, as in previous studies. With outflows, predicted DLA
kinematics are in much better agreement with observations. Comparing two
outflow models, we find that a model based on momentum-driven wind scalings
provides the best match to the observed DLA kinematic statistics of Prochaska &
Wolfe. In this model, DLAs typically arise a few kpc away from galaxies that
would be identified in emission. Narrow DLAs can arise from any halo and galaxy
mass, but wide ones only arise in halos with mass >10^11 Mo, from either large
central or small satellite galaxies. This implies that the success of this
outflow model originates from being most efficient at pushing gas out from
small satellite galaxies living in larger halos. This increases the
cross-section for large halos relative to smaller ones, thereby yielding wider
kinematics. Our simulations do not include radiative transfer effects or
detailed metal tracking, and outflows are modeled heuristically, but they
strongly suggest that galactic outflows are central to understanding DLA
kinematics. An interesting consequence is that DLA kinematics may place
constraints on the nature and efficiency of gas ejection from high-z galaxies.Comment: submitted to MNRA
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