11,179 research outputs found
Updated Mass Scaling Relations for Nuclear Star Clusters and a Comparison to Supermassive Black Holes
We investigate whether nuclear star clusters and supermassive black holes
follow a common set of mass scaling relations with their host galaxy's
properties, and hence can be considered to form a single class of central
massive object. We have compiled a large sample of galaxies with measured
nuclear star cluster masses and host galaxy properties from the literature and
fit log-linear scaling relations. We find that nuclear star cluster mass,
M_{NC}, correlates most tightly with the host galaxy's velocity dispersion: log
M_{NC} = (2.11 \pm 0.31) log (\sigma/54) + (6.63 \pm 0.09), but has a slope
dramatically shallower than the relation defined by supermassive black holes.
We find that the nuclear star cluster mass relations involving host galaxy (and
spheroid) luminosity and stellar and dynamical mass, intercept with but are in
general shallower than the corresponding black hole scaling relations. In
particular M_{NC} \propto {M}_{Gal,dyn}^{0.55 \pm 0.15}; the nuclear cluster
mass is not a constant fraction of its host galaxy or spheroid mass. We
conclude that nuclear stellar clusters and supermassive black holes do not form
a single family of central massive objects.Comment: 8 pages, 3 figure
Breaking the law: the M_{bh}-M_{spheroid} mass relations for core-Sersic and Sersic galaxies
The popular log-linear relation between supermassive black hole mass, M_bh,
and the dynamical mass of the host spheroid, M_sph, is shown to require a
significant correction. Core galaxies, typically with M_bh > 2x10^8 M_Sun and
thought to be formed in dry merger events, are shown to be well described by a
linear relation for which the median black hole mass is 0.36% - roughly double
the old value of constancy. Of greater significance is that M_bh ~ (M_sph)^2
among the (non-pseudobulge) lower-mass systems: specifically, log[M_bh/M_Sun] =
(1.92+/-0.38)log[M_sph/7x10^{10}M_Sun] + (8.38+/-0.17). `Classical' spheroids
hosting a 10^6 M_Sun black hole will have M_bh/M_sph ~ 0.025%. These new
relations (i) bring consistency to the relation M_bh ~ sigma^5 and the fact
that L ~ sigma^x with exponent x equal to 5 and 2 for bright (M_B < -20.5 mag)
and faint spheroids, respectively, (ii) mimic the non-(log-linear) behavior in
the M_bh-(Sersic n) diagram, (iii) necessitate the existence of a previously
over-looked M_bh ~ L^{2.5} relation for Sersic (i.e.\ not core-Sersic)
galaxies, and (iv) resolve past conflicts (in mass prediction) with the
M_bh-sigma relation at the low-mass end. Furthermore, the bent nature of the
M_bh-M_sph relation for `classical' spheroids will have a host of important
implications that relate to (i) galaxy/black hole formation theories, (ii)
searches for the fundamental black hole scaling relation, (iii) black hole mass
predictions in other galaxies, (iv) alleged pseudobulge detections, (v)
estimates of the black hole mass function and mass density based on luminosity
functions, (vi) predictions for space-based gravitational wave detections,
(vii) connections with nuclear star cluster scaling relations, (viii)
evolutionary studies over different cosmic epochs, (ix) comparisons and
calibrations matching inactive black hole masses with low-mass AGN data, and
more.Comment: 4.5 pages plus reference
Inconsistent models of artihmetic Part II : The general case
The paper establishes the general structure of the inconsistent models of arithmetic of [7]. It is shown that such models are constituted by a sequence of nuclei. The nuclei fall into three segments: the first contains improper nuclei: the second contains proper nuclei with linear chromosomes: the third contains proper nuclei with cyclical chromosomes. The nuclei have periods which are inherited up the ordering. It is also shown that the improper nuclei can have the order type of any ordinal. of the nationals. or of any other order type that can be embedded in the rationals in a certain way
Simulation of bipartite qudit correlations
We present a protocol to simulate the quantum correlations of an arbitrary
bipartite state, when the parties perform a measurement according to two
traceless binary observables. We show that bits of classical
communication is enough on average, where is the dimension of both systems.
To obtain this result, we use the sampling approach for simulating the quantum
correlations. We discuss how to use this method in the case of qudits.Comment: 7 page
Social creativity: Turning barriers into opportunities for collaborative design
ABSTRACT � conceptual (across different communities of practice), requiring support for common ground and shared understanding [Fischer, 2001; Resnick, 1991]; and Design is a ubiquitous activity. The complexity of design problems requires communities rather than individuals to address, frame, and solve them. These design communities have to cope with the following barriers: (1) spatial (across distance), (2) temporal (across time), (3) conceptual (across different communities of practice, and (4) technological (between persons and artifacts). Over the last decade, we have addressed these barriers and have tried to create socio-technical environments to turn them into opportunities for enhancing the social creativity of design communities
Experimental Design for the Gemini Planet Imager
The Gemini Planet Imager (GPI) is a high performance adaptive optics system
being designed and built for the Gemini Observatory. GPI is optimized for high
contrast imaging, combining precise and accurate wavefront control, diffraction
suppression, and a speckle-suppressing science camera with integral field and
polarimetry capabilities. The primary science goal for GPI is the direct
detection and characterization of young, Jovian-mass exoplanets. For plausible
assumptions about the distribution of gas giant properties at large semi-major
axes, GPI will be capable of detecting more than 10% of gas giants more massive
than 0.5 M_J around stars younger than 100 Myr and nearer than 75 parsecs. For
systems younger than 1 Gyr, gas giants more massive than 8 M_J and with
semi-major axes greater than 15 AU are detected with completeness greater than
50%. A survey targeting young stars in the solar neighborhood will help
determine the formation mechanism of gas giant planets by studying them at ages
where planet brightness depends upon formation mechanism. Such a survey will
also be sensitive to planets at semi-major axes comparable to the gas giants in
our own solar system. In the simple, and idealized, situation in which planets
formed by either the "hot-start" model of Burrows et al. (2003) or the core
accretion model of Marley et al. (2007), a few tens of detected planets are
sufficient to distinguish how planets form.Comment: 15 pages, 9 figures, revised after referee's comments and resubmitted
to PAS
Extending the M_(bh)-sigma diagram with dense nuclear star clusters
Abridged: Four new nuclear star cluster masses, M_nc, plus seven upper
limits, are provided for galaxies with previously determined black hole masses,
M_bh. Together with a sample of 64 galaxies with direct M_bh measurements, 13
of which additionally now have M_nc measurements rather than only upper limits,
plus an additional 29 dwarf galaxies with available M_nc measurements and
velocity dispersions sigma, an (M_bh + M_nc)-sigma diagram is constructed.
Given that major dry galaxy merger events preserve the M_bh/L ratio, and given
that L ~ sigma^5 for luminous galaxies, it is first noted that the observation
M_bh ~ sigma^5 is consistent with expectations. For the fainter elliptical
galaxies it is known that L ~ sigma^2, and assuming a constant M_nc/L ratio
(Ferrarese et al.), the expectation that M_nc ~ sigma^2 is in broad agreement
with our new observational result that M_nc ~ sigma^{1.57\pm0.24}. This
exponent is however in contrast to the value of ~4 which has been reported
previously and interpreted in terms of a regulating feedback mechanism from
stellar winds.Comment: 6 pages, 2 figures. Submitted 08/08/2011 to MNRAS, first referee
report received 19/01/2012, accepted 10/02/201
Dynamical preparation of EPR entanglement in two-well Bose-Einstein condensates
We propose to generate Einstein-Podolsky-Rosen (EPR) entanglement between
groups of atoms in a two-well Bose-Einstein condensate using a dynamical
process similar to that employed in quantum optics. The local nonlinear S-wave
scattering interaction has the effect of creating a spin squeezing at each
well, while the tunneling, analogous to a beam splitter in optics, introduces
an interference between these fields that results in an inter-well
entanglement. We consider two internal modes at each well, so that the
entanglement can be detected by measuring a reduction in the variances of the
sums of local Schwinger spin observables. As is typical of continuous variable
(CV) entanglement, the entanglement is predicted to increase with atom number,
and becomes sufficiently strong at higher numbers of atoms that the EPR paradox
and steering non-locality can be realized. The entanglement is predicted using
an analytical approach and, for larger atom numbers, stochastic simulations
based on truncated Wigner function. We find generally that strong tunnelling is
favourable, and that entanglement persists and is even enhanced in the presence
of realistic nonlinear losses.Comment: 15 pages, 19 figure
The JCMT Transient Survey: An Extraordinary Submillimetre Flare in the T Tauri Binary System JW 566
The binary T Tauri system JW 566 in the Orion Molecular Cloud underwent an
energetic, short-lived flare observed at submillimetre wavelengths by the
SCUBA-2 instrument on 26 November 2016 (UT). The emission faded by nearly 50%
during the 31 minute integration. The simultaneous source fluxes averaged over
the observation are 500 +/- 107 mJy/beam at 450 microns and 466 +/- 47 mJy/beam
at 850 microns. The 850 micron flux corresponds to a radio luminosity of
erg/s/Hz, approximately one order of magnitude
brighter (in terms of ) than that of a flare of the young star
GMR-A, detected in Orion in 2003 at 3mm. The event may be the most luminous
known flare associated with a young stellar object and is also the first
coronal flare discovered at sub-mm wavelengths. The spectral index between 450
microns and 850 microns of is broadly consistent with
non-thermal emission. The brightness temperature was in excess of
K. We interpret this event to be a magnetic reconnection that
energised charged particles to emit gyrosynchrotron/synchrotron radiation.Comment: Accepted in ApJ. 16 pages (single column), 6 figure
The role of Cytochrome P450s towards the control of ticks and other arthropods
Introduction
Ticks most notably Rhipicephalus (Boophilus) microplus are becoming increasingly resistant to acaricides .This resistance is often broken down into the 3 main mechanisms of detoxification involving 3 groups of enzymes; Cytochrome P450s (CYPs), Glutathione-S-transferases (GST) or Esterases (EST or carboxylesterases) (Foil et al., 2004)
Material and Methods
Acaricide resistance research to date, has focused on identifying which acaricides are becoming redundant in terms of effectiveness to kill the arthropod. Often, this research uses mortality based experimental procedures (Li et al., 2003; Miller et al., 2005), and investigations into the molecular/enzymatic basis of resistance have focused on GSTs and ESTs rather than CYPs. Another method used in our laboratory investigating the role of CYPs in resistance is employing tick cell cultures as a model system developed in partnership with the Roslin Institute (Bell-Sakyi et al., 2007). This system provides an ideal way to monitor CYP expression before, during and after various treatments such as acaricides. In Anopheles gambiae, expression levels of CYPs, GSTs and ESTs were monitored using a microarray following infection of the mosquito by Plasmodium (Felix et al., 2010). A similar micro array approach could be employed with ticks and mites as more data becomes available.
Results
Our group is monitoring the expression levels of different CYPs in tick cell lines as well as looking to identify novel CYPs and work on phylogenetic links for those genes between different arthropod groups. We are also investigating polymorphisms between different tick cell lines and different arthropod species.
Discussion and Conclusions
Among the arthropods, research strongly suggests that the CYP6 (Hemingway et al., 2004) and CYP9families are most highly associated with xenobiotic resistance and a lot of research has been carried out looking at these CYP families in various insect species. In mosquito species some resistance to pesticides is due to their CYP enzymes evolving to detoxify these chemicals at increasing concentrations (Nikou et al., 2003
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