The Quest for Bandwidth Estimation Techniques for large-scale Distributed Systems

In recent years the research community has developed many techniques to estimate the end-to-end available bandwidth of an Internet path. This important metric has been proposed for use in several distributed systems and, more recently, has even been considered to improve the congestion control mechanism of TCP. Thus, it has been suggested that some existing estimation techniques could be used for this purpose. However, existing tools were not designed for large-scale deployments and were mostly validated in controlled settings, considering only one measurement running at a time. In this paper, we argue that current tools, while offering good estimates when used alone, might not work in large-scale systems where several estimations severely interfere with each other. We analyze the properties of the measurement paradigms employed today and discuss their functioning, study their overhead and analyze their interference. Our testbed results show that current techniques are insufficient as they are. Finally, we will discuss and propose some principles that should be taken into account for including available bandwidth measurements in large-scale distributed systems. 1

Tanaka-Tagoshi Parametrization of post-1PN Spin-Free Gravitational Wave Chirps: Equispaced and Cardinal Interpolated Lattices For First Generation Interferometric Antennas

The spin-free binary-inspiral parameter-space introduced by Tanaka and Tagoshi to construct a uniformly-spaced lattice of templates at (and possibly beyond) $2.5PN$ order is shown to work for all first generation interferometric gravitational wave antennas. This allows to extend the minimum-redundant cardinal interpolation techniques of the correlator bank developed by the Authors to the highest available order PN templates. The total number of 2PN templates to be computed for a minimal match $\Gamma=0.97$ is reduced by a factor 4, as in the 1PN case.Comment: 9 pages, 8 figures, 3 tables, accepted for publication in Phys. Rev.

Rejection Properties of Stochastic-Resonance-Based Detectors of Weak Harmonic Signals

In (V. Galdi et al., Phys. Rev. E57, 6470, 1998) a thorough characterization in terms of receiver operating characteristics (ROCs) of stochastic-resonance (SR) detectors of weak harmonic signals of known frequency in additive gaussian noise was given. It was shown that strobed sign-counting based strategies can be used to achieve a nice trade-off between performance and cost, by comparison with non-coherent correlators. Here we discuss the more realistic case where besides the sought signal (whose frequency is assumed known) further unwanted spectrally nearby signals with comparable amplitude are present. Rejection properties are discussed in terms of suitably defined false-alarm and false-dismissal probabilities for various values of interfering signal(s) strength and spectral separation.Comment: 4 pages, 5 figures. Misprints corrected. PACS numbers added. RevTeX

Optimum Placement of Post-1PN GW Chirp Templates Made Simple at any Match Level via Tanaka-Tagoshi Coordinates

A simple recipe is given for constructing a maximally sparse regular lattice of spin-free post-1PN gravitational wave chirp templates subject to a given minimal match constraint, using Tanaka-Tagoshi coordinates.Comment: submitted to Phys. Rev.

Un archivo del folklore nacional : La Encuesta de Magisterio de 1921

En la primera mitad del siglo pasado tuvo lugar el principal proceso de relevamiento, recolección y documentación de las manifestaciones orales de la literatura nacional. El proyecto más importante de esta etapa fue la Encuesta del Magisterio de 1921, cuyos resultados fueron reunidos en la Colección de Folklore. En ese año el Ministerio de Educación de la Nación encargó a los maestros de las escuelas nacionales de todo el país la recolección de los elementos folklóricos que encontraran en su jurisdicción. Nuestra propuesta consiste en presentar la Encuesta de Magisterio en el marco de las políticas culturales en las que surge y que la convierten en una herramienta didáctica empleada por los estudiosos y colectores letrados para transmitir los "valores" nacionalesFil: Espósito, Fabio. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.Fil: Di Croce, Ely V.. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina

How Many Templates for GW Chirp Detection? The Minimal-Match Issue Revisited

In a recent paper dealing with maximum likelihood detection of gravitational wave chirps from coalescing binaries with unknown parameters we introduced an accurate representation of the no-signal cumulative distribution of the supremum of the whole correlator bank. This result can be used to derive a refined estimate of the number of templates yielding the best tradeoff between detector's performance (in terms of lost signals among those potentially detectable) and computational burden.Comment: submitted to Class. Quantum Grav. Typing error in eq. (4.8) fixed; figure replaced in version

Propagation of semantic information between orthophoto and 3D replica: a H-BIM system for the north transept of Pisa Cathedral

This contribution proposes a methodological approach for the transfer of annotations between orthophotos and 3D digital heritage models, relying on a mesh-based/point-based representation. The workflow leverages on the exploitation of 2D/3D projective relations and on the identification, propagation, modelling and tiling of virtual models of architectural heritage. Referring to the significant case study of Pisa Cathedral, the method is tested to ensure an informative continuum between 2D medias and 3D representations, in terms of morphology, geometry and semantic enrichment. At first, a high resolution ortho-photo is created to support studies related to conservation and restoration, e.g. to highlight degradation patterns and materials as well as to distinguish cracks, frescoed surfaces, decorations. Then, the information is translated from the 2D support to a virtual 3D mockup: this step is essential to ensure a complete understanding of the architectural heritage object, that can thus be studied in its entirety, considering its morphological complexities. The proposed approach provides a more effective system for the transfer and exchange of semantic information from high-resolution orthophotos to semantically rich 3D models, that can be fundamental even in view of the construction of Heritage-Building Information Modeling (H-BIM) environments

Surface roughness effect on ultracold neutron interaction with a wall and implications for computer simulations

We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that re-ported a large discrepancy of neutron lifetime with the current particle data value. Our partial re-analysis suggests the possibility of systematic effects that were not included in this publication.Comment: 39 pages, 9 figures; additional calculations include

Effect of an Acute Bout of Low-, Moderate, and High-Intensity Aerobic Exercise on Immediate and Delayed Fractionated Response Time

In the present investigation, we investigated the role of three intensities of aerobic exercise (Low Intensity [LI], Moderate Intensity [MI], High Intensity [HI]) on IPC using a unique method to fractionate RPT into three components: (1) RT, which is the interval between the onset of the stimulus signal and the onset of muscle activity in the responding muscle (cognitive-decision making component), (2) movement time (MT), which is the time interval between the onset of muscle activation and completion of the required motor response, and (3) RPT, which encompasses both RT and MT. Movement time reflects more the muscular components of the stimulus-response action, whereas RT reflects the duration of all earlier stages of information processing