73,592 research outputs found
What We Find in the Sea
Personal essay in which the author recounts his struggle to come to terms with his lack of grief over his grandfather’s death
A fast analysis for thread-local garbage collection with dynamic class loading
Long-running, heavily multi-threaded, Java server applications make stringent demands of garbage collector (GC) performance. Synchronisation of all application threads before garbage collection is a significant bottleneck for JVMs that use native threads. We present a new static analysis and a novel GC framework designed to address this issue by allowing independent collection of thread-local heaps. In contrast to previous work, our solution safely classifies objects even in the presence of dynamic class loading, requires neither write-barriers that may do unbounded work, nor synchronisation, nor locks during thread-local collections; our analysis is sufficiently fast to permit its integration into a high-performance, production-quality virtual machine
Neutrino parameters and the -dominated scenario of leptogenesis
We briefly review the main aspects of leptogenesis, describing both the
unflavoured and the flavoured versions of the -dominated scenario. A study
of the success rates of both classes of models has been carried out. We comment
on these results and discuss corrective effects to this simplest scenario.
Focusing on the flavoured case, we consider the conditions required by strong
thermal leptogenesis, where the final asymmetry is fully independent of the
initial conditions. Barring strong cancellations in the seesaw formula and in
the flavoured decay parameters, we show that strong thermal leptogenesis
favours a lightest neutrino mass m_1\gtrsim10\,\mbox{meV} for normal ordering
(NO) and m_1\gtrsim 3\,\mbox{meV} for inverted ordering (IO). Finally, we
briefly comment on the power of absolute neutrino mass scale experiments to
either support or severely corner strong thermal leptogenesis.Comment: Contribution to the Proceedings of the NuPhys2013 Conference:
Prospects in Neutrino Physics, 19-20 December 2013, IOP, Londo
Fuelling Active Galactic Nuclei
We suggest that most nearby active galactic nuclei are fed by a series of
small--scale, randomly--oriented accretion events. Outside a certain radius
these events promote rapid star formation, while within it they fuel the
supermassive black hole. We show that the events have a characteristic time
evolution. This picture agrees with several observational facts. The expected
luminosity function is broadly in agreement with that observed for
moderate--mass black holes. The spin of the black hole is low, and aligns with
the inner disc in each individual feeding event. This implies radio jets
aligned with the axis of the obscuring torus, and uncorrelated with the
large--scale structure of the host galaxy. The ring of young stars observed
about the Galactic Centre are close to where our picture predicts that star
formation should occur.Comment: MNRAS, in pres
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