Comparison of post-Newtonian templates for extreme mass ratio inspirals

Extreme mass ratio inspirals (EMRIs), the inspirals of compact objects into supermassive black holes, are important gravitational wave sources for the Laser Interferometer Space Antenna (LISA). We study the performance of various post-Newtonian (PN) template families relative to the high precision numerical waveforms in the context of EMRI parameter estimation with LISA. Expressions for the time domain waveforms TaylorT1, TaylorT2, TaylorT3, TaylorT4 and TaylorEt are derived up to 22PN order, i.e $\mathcal{O}(v^{44})$ ($v$ is the characteristic velocity of the binary) beyond the Newtonian term, for a test particle in a circular orbit around a Schwarzschild black hole. The phase difference between the above 22PN waveform families and numerical waveforms are evaluated during two-year inspirals for two prototypical EMRI systems with mass ratios $10^{-4}$ and $10^{-5}$. We find that the dephases (in radians) for TaylorT1 and TaylorT2, respectively, are about $10^{-9}$ ($10^{-2}$) and $10^{-9}$ ($10^{-3}$) for mass ratio $10^{-4}$ ($10^{-5}$). This suggests that using 22PN TaylorT1 or TaylorT2 waveforms for parameter estimation of EMRIs will result in accuracies comparable to numerical waveform accuracy for most of the LISA parameter space. On the other hand, from the dephase results, we find that TaylorT3, TaylorT4 and TaylorEt fare relatively poorly as one approaches the last stable orbit. This implies that, as for comparable mass binaries using the 3.5PN phase of waveforms, the 22PN TaylorT3 and TaylorEt approximants do not perform well enough for the EMRIs. The reason underlying the poor performance of TaylorT3, TaylorT4 and TaylorEt relative to TaylorT1 and TaylorT2 is finally examined.Comment: 10 page

Being Home: Jazz Authority and the Politics of Place

Songs of the Unsung: The Musical and Social Journey of Horace Tapscott sets forth an astonishing, searingly honest view of one segment of music history that is indeed unsung. Tapscott (1934-1999) was a pianist, composer, bandleader, and social activist who spent most of his life in the Mrican American communities of Los Angeles. In 1998, sociologist Steven Isoardi collaborated with several generations of Los Angeles jazz musicians to compile a vital oral history of that city's rich, undervalued role in African American music and culture (Bryant et al. 1998). Among Isoardi's interview subjects was Tapscott, who also served as a co-editor of the compilation. Several hours of conversation with Tapscott were distilled into a handful of pages for his entry in that volume. Subsequent to Tapscott's death, Isoardi arranged these transcribed recollections into a coherent, compelling autobiography. The resultant memoir reminds us with stunning candor that too much has happened under the radar of the jazz industry. Released in time for the holiday season in 2000, The Oxford Companion to Jazz (hereafter OCJ) endeavors to be viewed as "the one indispensable publication in the field," to quote a highlighted phrase in the back-of-thejacket testimonial by seasoned producer George Avakian. Editor Bill Kirchner commissioned sixty brief thematic chapters by fifty-nine different contributors, including journalists, critics, scholars, and musicians. Many of the chapters take the form of mini-histories, covering important individual figures of jazz, single canonical stylistic eras by decade and genre, notable musicians by instrument, or specific jazz histories by region

A Cellular Resolution Map of Barrel Cortex Activity during Tactile Behavior

SummaryComprehensive measurement of neural activity remains challenging due to the large numbers of neurons in each brain area. We used volumetric two-photon imaging in mice expressing GCaMP6s and nuclear red fluorescent proteins to sample activity in 75% of superficial barrel cortex neurons across the relevant cortical columns, approximately 12,000 neurons per animal, during performance of a single whisker object localization task. Task-related activity peaked during object palpation. An encoding model related activity to behavioral variables. In the column corresponding to the spared whisker, 300 layer (L) 2/3 pyramidal neurons (17%) each encoded touch and whisker movements. Touch representation declined by half in surrounding columns; whisker movement representation was unchanged. Following the emergence of stereotyped task-related movement, sensory representations showed no measurable plasticity. Touch direction was topographically organized, with distinct organization for passive and active touch. Our work reveals sparse and spatially intermingled representations of multiple tactile features.Video Abstrac

Remedy: Network-Aware Steady State VM Management for Data Centers

Abstract. Steady state VM management in data centers should be network-aware so that VM migrations do not degrade network performance of other flows in the network, and if required, a VM migration can be intelligently orchestrated to decongest a network hotspot. Recent research in network-aware management of VMs has focused mainly on an optimal network-aware initial placement of VMs and has largely ignored steady state management. In this context, we present the design and implementation of Remedy. Remedy ranks target hosts for a VM migration based on the associated cost of migration, available bandwidth for mi-gration and the network bandwidth balance achieved by a migration. It models the cost of migration in terms of additional network traffic generated during mi-gration. We have implemented Remedy as an OpenFlow controller application that detects the most congested links in the network and migrates a set of VMs in a network-aware manner to decongest these links. Our choice of target hosts ensures that neither the migration traffic nor the flows that get rerouted as a result of migration cause congestion in any part of the network. We validate our cost of migration model on a virtual software testbed using real VM migrations. Our simulation results using real data center traffic data demonstrate that selective network aware VM migrations can help reduce unsatisfied bandwidth by up to 80-100%