18,493 research outputs found
On the Intracluster Medium in Cooling Flow & Non-Cooling Flow Clusters
Recent X-ray observations have highlighted clusters that lack entropy cores.
At first glance, these results appear to invalidate the preheated ICM models.
We show that a self-consistent preheating model, which factors in the effects
of radiative cooling, is in excellent agreement with the observations.
Moreover, the model naturally explains the intrinsic scatter in the L-T
relation, with ``cooling flow'' and ``non-cooling flow'' systems corresponding
to mildly and strongly preheated systems, respectively. We discuss why
preheating ought to be favoured over merging as a mechanism for the origin of
``non-cooling flow'' clusters.Comment: 4 pages, to appear in the proceedings of the "Multiwavelength
Cosmology" Conference held in Mykonos, Greece, June 2003, ed. M. Plionis
(Kluwer
Impact of sustainable agriculture practices on farmland value
falsefile:///C:/Users/imccarth/Downloads/TPF_RuralValuation_report(v3)DIGITAL.pdfThe Property Foundatio
A comparative study of terminal business curricula in public junior colleges and private business schools
Thesis (Ed.M.)--Boston University, 1947. This item was digitized by the Internet Archive
Cosmology with velocity dispersion counts: an alternative to measuring cluster halo masses
The evolution of galaxy cluster counts is a powerful probe of several
fundamental cosmological parameters. A number of recent studies using this
probe have claimed tension with the cosmology preferred by the analysis of the
Planck primary CMB data, in the sense that there are fewer clusters observed
than predicted based on the primary CMB cosmology. One possible resolution to
this problem is systematic errors in the absolute halo mass calibration in
cluster studies, which is required to convert the standard theoretical
prediction (the halo mass function) into counts as a function of the observable
(e.g., X-ray luminosity, Sunyaev-Zel'dovich flux, optical richness). Here we
propose an alternative strategy, which is to directly compare predicted and
observed cluster counts as a function of the one-dimensional velocity
dispersion of the cluster galaxies. We argue that the velocity dispersion of
groups/clusters can be theoretically predicted as robustly as mass but, unlike
mass, it can also be directly observed, thus circumventing the main systematic
bias in traditional cluster counts studies. With the aid of the BAHAMAS suite
of cosmological hydrodynamical simulations, we demonstrate the potential of the
velocity dispersion counts for discriminating even similar CDM models.
These predictions can be compared with the results from existing redshift
surveys such as the highly-complete Galaxy And Mass Assembly (GAMA) survey, and
upcoming wide-field spectroscopic surveys such as the Wide Area Vista
Extragalactic Survey (WAVES) and the Dark Energy Survey Instrument (DESI).Comment: 15 pages, 13 figures. Accepted for publication in MNRAS. New section
on cosmological forecasts adde
Exploring the unknown: assumptions about allelic architecture and strategies for susceptibility variant discovery
Identification of common-variant associations for many common disorders has been highly effective, but the loci detected so far typically explain only a small proportion of the genetic predisposition to disease. Extending explained genetic variance is one of the major near-term goals of human genetic research. Next-generation sequencing technologies offer great promise, but optimal strategies for their deployment remain uncertain, not least because we lack a clear view of the characteristics of the variants being sought. Here, I discuss what can and cannot be inferred about complex trait disease architecture from the information currently available and review the implications for future research strategies
Business Succession in the New Zealand Horticulture Industry
falsehttps://www.mpi.govt.nz/dmsdocument/44617-Business-Succession-in-the-New-Zealand-Horticulture-IndustryMinistry for Primary Industrie
Sum rule of the correlation function
We discuss a sum rule satisfied by the correlation function of two particles
with small relative momenta. The sum rule, which results from the completeness
condition of the quantum states of the two particles, is first derived and then
we check how it works in practice. The sum rule is shown to be trivially
satisfied by free particle pair, and then there are considered three different
systems of interacting particles. We discuss a pair of neutron and proton in
the s-wave approximation and the case of the so-called hard spheres with the
phase shifts taken into account up to l=4. Finally, the Coulomb system of two
charged particles is analyzed.Comment: 18 pages, 18 figures, revised, to appear in Phys. Rev.
Barrier and internal wave contributions to the quantum probability density and flux in light heavy-ion elastic scattering
We investigate the properties of the optical model wave function for light
heavy-ion systems where absorption is incomplete, such as Ca
and O around 30 MeV incident energy. Strong focusing effects
are predicted to occur well inside the nucleus, where the probability density
can reach values much higher than that of the incident wave. This focusing is
shown to be correlated with the presence at back angles of a strong enhancement
in the elastic cross section, the so-called ALAS (anomalous large angle
scattering) phenomenon; this is substantiated by calculations of the quantum
probability flux and of classical trajectories. To clarify this mechanism, we
decompose the scattering wave function and the associated probability flux into
their barrier and internal wave contributions within a fully quantal
calculation. Finally, a calculation of the divergence of the quantum flux shows
that when absorption is incomplete, the focal region gives a sizeable
contribution to nonelastic processes.Comment: 16 pages, 15 figures. RevTeX file. To appear in Phys. Rev. C. The
figures are only available via anonynous FTP on
ftp://umhsp02.umh.ac.be/pub/ftp_pnt/figscat
An alternative derivation of the gravitomagnetic clock effect
The possibility of detecting the gravitomagnetic clock effect using
artificial Earth satellites provides the incentive to develop a more intuitive
approach to its derivation. We first consider two test electric charges moving
on the same circular orbit but in opposite directions in orthogonal electric
and magnetic fields and show that the particles take different times in
describing a full orbit. The expression for the time difference is completely
analogous to that of the general relativistic gravitomagnetic clock effect in
the weak-field and slow-motion approximation. The latter is obtained by
considering the gravitomagnetic force as a small classical non-central
perturbation of the main central Newtonian monopole force. A general expression
for the clock effect is given for a spherical orbit with an arbitrary
inclination angle. This formula differs from the result of the general
relativistic calculations by terms of order c^{-4}.Comment: LaTex2e, 11 pages, 1 figure, IOP macros. Submitted to Classical and
Quantum Gravit
- …