163,188 research outputs found
Comment on ``Nonlinear band structure in Bose-Einstein condensates: Nonlinear Sch\"odinger equation with a Kronig Penney potential"
In their recent paper [Phys. Rev. A 71, 033622], B. T. Seaman et al. studied
Bloch states of the condensate wave function in a Kronig-Penney potential and
calculated the band structure. They argued that the effective mass is always
positive when a swallow-tail energy loop is present in the band structure. In
this comment, we reexamine their argument by actually calculating the effective
mass. It is found that there exists a region where the effective mass is
negative even when a swallow-tail is present. Based on this fact, we discuss
the interpretation of swallow-tails in terms of superfluidity.Comment: 3 pages, 3 figure
Sexual selection in the Swallow Hirundo rustica - A review
Darwinian theory of sexual selection and its development up to the present state
of knowledge are sketched. The most important results of empirical studies on sexual selection
in the Swallow Hirundo rustica are reviewed. The Swallow is a socially monogamous, slightly
sexually dimorphic avian species. Long tail streamers are considered as sexual ornaments of
males. Female preference for long and symmetric male tails has been inferred on both
observational and experimental grounds. Experimental elongation of the tail causes short-term
benefits and long-term costs in male reproductive performance. Behavioural consequences of
sexual selection acting in the Swallow are discussed. An aerodynamic role of male tail
streamers is also considered.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę
Overview of Swallow --- A Scalable 480-core System for Investigating the Performance and Energy Efficiency of Many-core Applications and Operating Systems
We present Swallow, a scalable many-core architecture, with a current
configuration of 480 x 32-bit processors.
Swallow is an open-source architecture, designed from the ground up to
deliver scalable increases in usable computational power to allow
experimentation with many-core applications and the operating systems that
support them.
Scalability is enabled by the creation of a tile-able system with a
low-latency interconnect, featuring an attractive communication-to-computation
ratio and the use of a distributed memory configuration.
We analyse the energy and computational and communication performances of
Swallow. The system provides 240GIPS with each core consuming 71--193mW,
dependent on workload. Power consumption per instruction is lower than almost
all systems of comparable scale.
We also show how the use of a distributed operating system (nOS) allows the
easy creation of scalable software to exploit Swallow's potential. Finally, we
show two use case studies: modelling neurons and the overlay of shared memory
on a distributed memory system.Comment: An open source release of the Swallow system design and code will
follow and references to these will be added at a later dat
A Meal for the Man on the Redline
These words will bite,
Acid bubbling
At the pit of your bowels
Vowels volatile won’t
Be easy to swallow. [excerpt
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