123 research outputs found
Efficient microwave-assisted synthetic protocols and in silico behaviour prediction of per-substituted β-cyclodextrins
Coherent-incoherent transition in the sub-Ohmic spin-boson model
We study the spin-boson model with a sub-Ohmic bath using a variational
method. The transition from coherent dynamics to incoherent tunneling is found
to be abrupt as a function of the coupling strength and to exist for
any power , where the bath coupling is described by . We find non-monotonic temperature dependence of the
two-level gap and a re-entrance regime close to the transition due
to non-adiabatic low-frequency bath modes. Differences between thermodynamic
and dynamic conditions for the transition as well as the limitations of the
simplified bath description are discussed.Comment: 12 pages, 4 figure
Environmental dependence of 8 μm luminosity functions of galaxies at z ~ 0.8: Comparison between RXJ1716.4+6708 and the AKARI NEP-deep field
Aims. We aim to reveal environmental dependence of infrared luminosity functions (IR LFs) of galaxies at z ~ 0.8 using the AKARI
satellite. AKARI’s wide field of view and unique mid-IR filters help us to construct restframe 8 μm LFs directly without relying on
SED models.
Methods. We construct restframe 8 μm IR LFs in the cluster region RXJ1716.4+6708 at z = 0.81, and compare them with a blank
field using the AKARI north ecliptic pole deep field data at the same redshift. AKARI’s wide field of view (10' × 10') is suitable to
investigate wide range of galaxy environments. AKARI’s 15 μm filter is advantageous here since it directly probes restframe 8 μm at
z ~ 0.8, without relying on a large extrapolation based on a SED fit, which was the largest uncertainty in previous work.
Results. We have found that cluster IR LFs at restframe 8 μm have a factor of 2.4 smaller L^∗ and a steeper faint-end slope than that
of the field. Confirming this trend, we also found that faint-end slopes of the cluster LFs becomes flatter and flatter with decreasing
local galaxy density. These changes in LFs cannot be explained by a simple infall of field galaxy population into a cluster. Physics
that can preferentially suppress IR luminous galaxies in high density regions is required to explain the observed results
A Bose-Einstein condensation model for high-temperature superconductivity
I propose that a dopant charge singlet bonding state may arise from the
hybridization of molecular orbitals in a cluster containing 13 Cu atoms in the
CuO2 plane of the superconducting cuprates. This singlet state forms a
pre-formed pair with low binding energy that is spatially bounded and weakly
interacting, and that can undergo Bose-Einstein condensation. I show that this
model is able to account, in a quantitative and natural way, for many of the
thermodynamic and electronic characteristics of the superconducting cuprates,
including many of the key experimental ARPES, muSR and microwave results on the
temperature and doping dependencies of both the superfluid density and the
pairing strengths (superconducting gap, leading-edge-midpoint and psuedogap) in
these high-temperature superconductors.Comment: 28 pages, 9 figures, submitted to Phys. Rev.
Developmental expression of the cucumber <i>Cs-XTH1</i> and <i>Cs-XTH3</i> genes, encoding xyloglucan endotransglucosylase/hydrolases, can be influenced by mechanical stimuli
Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: I. The role of ISM pressure & the Molecular Cloud Dissipation Timescale
In this paper, we combine the stellar spectral synthesis code STARBURST 99,
the nebular modelling code MAPPINGS IIIq, a 1-D dynamical evolution model of
\HII regions around massive clusters of young stars and a simplified model of
synchrotron emissivity to produce purely theoretical self-consistent synthetic
spectral energy distributions (SEDs) for (solar metallicity) starbursts lasting
some years. These SEDs extend from the Lyman Limit to beyond 21 cm. We
find that two ISM parameters control the form of the SED; the pressure in the
diffuse phase of the ISM (or, equivalently, its density), and the molecular
cloud dissipation timescale. We present detailed SED fits to Arp 220 and NGC
6240, and we give the predicted colors for starburst galaxies derived from our
models for the IRAS and the Spitzer Space Observatory MIPS and IRAC
instruments. Our models reproduce the spread in observed colors of starburst
galaxies. Finally, we present absolute calibrations to convert observed fluxes
into star formation rates in the UV (GALEX), at optical wavelengths
(H), and in the IR (IRAS or the Spitzer Space Observatory). (Abstract
Truncated)Comment: 56 pages, 16 figures, accepted by The Apstrophysical Journal For
version with full, colour figures go to
http://www.mso.anu.edu.au/~bgroves/starburst
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