3,205 research outputs found
The Tully-Fisher and mass-size relations from halo abundance matching
The Tully-Fisher relation (TFR) expresses the connection between rotating
galaxies and the dark matter haloes they inhabit, and therefore contains a
wealth of information about galaxy formation. We construct a general framework
to investigate whether models based on halo abundance matching are able to
reproduce the observed stellar mass TFR and mass-size relation (MSR), and use
the data to constrain galaxy formation parameters. Our model tests a range of
plausible scenarios, differing in the response of haloes to disc formation, the
relative angular momentum of baryons and dark matter, the impact of selection
effects, and the abundance matching parameters. We show that agreement with the
observed TFR puts an upper limit on the scatter between galaxy and halo
properties, requires weak or reversed halo contraction, and favours selection
effects that preferentially eliminate fast-rotating galaxies. The MSR
constrains the ratio of the disc to halo specific angular momentum to be
approximately in the range 0.6-1.2. We identify and quantify two problems that
models of this nature face. (1) They predict too large an intrinsic scatter for
the MSR, and (2) they predict too strong an anticorrelation between the TFR and
MSR residuals. We argue that resolving these problems requires introducing a
correlation between stellar surface density and enclosed dark matter mass.
Finally, we explore the expected difference between the TFRs of central and
satellite galaxies, finding that in the favoured models this difference should
be detectable in a sample of ~700 galaxies.Comment: 27 pages, 10 figures; revised to match published MNRAS versio
"They Punish Murderers, Thieves, Traitors and Sorcerers": Aboriginal Criminal Justice as Reported by Early French Observers
A common theme in the writings of European explorers, historians, and religious
emissaries who were among the first to comment on the inhabitants of the western
hemisphere was the absence in Aboriginal society of any concept of law. In some
cases these early commentators may not have interpreted what they saw correctly,
and they used French words with specific legal definitions that were not relevant in
the context of the behaviour they attempted to describe. Evidence from their writings,
especially those of the Jesuits, shows that there was in fact law among the
Native peoples of the northeast, and particularly criminal law, albeit of a different
kind and process than French law. In France, with retribution or deterrence as the
objective of the judicial system, the individual alone was responsible for his or her
actions and suffered punishment accordingly. In contrast, apart from cases of sorcery
or betrayal, which were punishable by death, Aboriginal justice sought to
restore social cohesion and harmony among the group by restitution, which was a
collective responsibility.L’absence de tout concept de droit dans la société autochtone est un thème récurrent
des écrits des explorateurs, historiens et émissaires religieux européens, qui furent
parmi les premiers à commenter le mode de vie des habitants de l’hémisphère ouest.
Dans certains cas, ces premiers commentateurs ont peut-être mal interprété ce
qu’ils ont vu et ils utilisaient des termes français à définition juridique précise ne
s’appliquant pas, dans le contexte, au comportement qu’ils tentaient de décrire.
Leurs écrits, surtout ceux des Jésuites, révèlent que le droit existait bel et bien chez
les peuples autochtones du Nord-Est, surtout une justice pénale, bien que d’un type
et aux mécanismes différents de ceux du droit français. En France, la rétribution et
la dissuasion étant l’objectif du système judiciaire, la personne était seule responsable
de ses actes et se voyait infliger des peines correspondantes. En revanche,
hormis les cas de sorcellerie ou de trahison, passibles de mort, la justice autochtone
cherchait à restaurer la cohésion et l’harmonie sociales au sein du groupe par la
restitution, ce qui était une responsabilité collective
Accurate and efficient spin integration for particle accelerators
Accurate spin tracking is a valuable tool for understanding spin dynamics in
particle accelerators and can help improve the performance of an accelerator.
In this paper, we present a detailed discussion of the integrators in the spin
tracking code gpuSpinTrack. We have implemented orbital integrators based on
drift-kick, bend-kick, and matrix-kick splits. On top of the orbital
integrators, we have implemented various integrators for the spin motion. These
integrators use quaternions and Romberg quadratures to accelerate both the
computation and the convergence of spin rotations. We evaluate their
performance and accuracy in quantitative detail for individual elements as well
as for the entire RHIC lattice. We exploit the inherently data-parallel nature
of spin tracking to accelerate our algorithms on graphics processing units.Comment: 43 pages, 17 figure
Advantages of 3D time-of-flight range imaging cameras in machine vision applications
Machine vision using image processing of traditional intensity images is in wide spread use. In many situations environmental conditions or object colours or shades cannot be controlled, leading to difficulties in correctly processing the images and requiring complicated processing algorithms. Many of these complications can be avoided by using range image data, instead of intensity data. This is because range image data represents the physical properties of object location and shape, practically independently of object colour or shading. The advantages of range image processing are presented, along with three example applications that show how robust machine vision results can be obtained with relatively simple range image processing in real-time applications
Montana Tribal Courts: Influencing the Development of Contemporary Indian Law
Montana Tribal Courts: Influencing the Development of Contemporary Indian La
Montana Tribal Courts: Influencing the Development of Contemporary Indian Law
Montana Tribal Courts: Influencing the Development of Contemporary Indian La
The Skn7 Response Regulator of \u3ci\u3eSaccharomyces cerevisiae\u3c/i\u3e Interacts with Hsf1 In Vivo and Is Required for the Induction of Heat Shock Genes by Oxidative Stress
The Skn7 response regulator has previously been shown to play a role in the induction of stress-responsive genes in yeast, e.g., in the induction of the thioredoxin gene in response to hydrogen peroxide. The yeast Heat Shock Factor, Hsf1, is central to the induction of another set of stress-inducible genes, namely the heat shock genes. These two regulatory trans-activators, Hsf1 and Skn7, share certain structural homologies, particularly in their DNA-binding domains and the presence of adjacent regions of coiled-coil structure, which are known to mediate protein–protein interactions. Here, we provide evidence that Hsf1 and Skn7 interact in vitro and in vivo and we show that Skn7 can bind to the same regulatory sequences as Hsf1, namely heat shock elements. Furthermore, we demonstrate that a strain deleted for the SKN7 gene and containing a temperature-sensitive mutation in Hsf1 is hypersensitive to oxidative stress. Our data suggest that Skn7 and Hsf1 cooperate to achieve maximal induction of heat shock genes in response specifically to oxidative stress. We further show that, like Hsf1, Skn7 can interact with itself and is localized to the nucleus under normal growth conditions as well as during oxidative stress
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