6,848 research outputs found

    Towards Informative Statistical Flow Inversion

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    This is the accepted version of 'Towards Informative Statistical Flow Inversion', archived originally at arXiv:0705.1939v1 [cs.NI] 14 May 2007.A problem which has recently attracted research attention is that of estimating the distribution of flow sizes in internet traffic. On high traffic links it is sometimes impossible to record every packet. Researchers have approached the problem of estimating flow lengths from sampled packet data in two separate ways. Firstly, different sampling methodologies can be tried to more accurately measure the desired system parameters. One such method is the sample-and-hold method where, if a packet is sampled, all subsequent packets in that flow are sampled. Secondly, statistical methods can be used to ``invert'' the sampled data and produce an estimate of flow lengths from a sample. In this paper we propose, implement and test two variants on the sample-and-hold method. In addition we show how the sample-and-hold method can be inverted to get an estimation of the genuine distribution of flow sizes. Experiments are carried out on real network traces to compare standard packet sampling with three variants of sample-and-hold. The methods are compared for their ability to reconstruct the genuine distribution of flow sizes in the traffic

    Particle-stabilized oscillating diver: a self-assembled responsive capsule

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    We report the experimental discovery of a self-assembled capsule, with density set by interfacial glass beads and an internal bubble, that automatically performs regular oscillations up and down a vial in response to a temperature gradient. Similar composites featuring interfacial particles and multiple internal compartments could be the solution to a variety of application challenges.Comment: 7 pages, 3 figure

    Native Spanish Speaker Intuition in Noun Gender Assignment

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    When an English word is borrowed into Spanish it has no specific gender and in order for the word to be used in the language it must be assigned a gender, either masculine or feminine. There are many different factors that may play a role in the assignment of gender to new English-origin words. This paper concentrates on English word final phonemes that do not correspond with the phonemes usually found in word final position in Spanish. For this study, words that are phonotactically possible in English but do not, in fact, exist were given to native Spanish speakers. The native Spanish speakers were then asked to assign the new words a gender. The words used in the study were designed to appear to be one gender according to their terminal phoneme. (ie. words ending in /o/ are generally masculine and words ending in /a/ are feminine) The definitions given to the words were designed to contradict the predictable gender associated with the terminal phoneme. In 90% of the cases the participants overlooked the definition and assigned the word to the gender associated with the terminal phoneme. This indicates that the meaning of the word and its function does not directly influence gender assignment. This study does indicate that the single most important factor in assigning gender to words borrowed from English into Spanish is the terminal phoneme

    Emulsification in binary liquids containing colloidal particles: a structure-factor analysis

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    We present a quantitative confocal-microscopy study of the transient and final microstructure of particle-stabilised emulsions formed via demixing in a binary liquid. To this end, we have developed an image-analysis method that relies on structure factors obtained from discrete Fourier transforms of individual frames in confocal image sequences. Radially averaging the squared modulus of these Fourier transforms before peak fitting allows extraction of dominant length scales over the entire temperature range of the quench. Our procedure even yields information just after droplet nucleation, when the (fluorescence) contrast between the two separating phases is scarcely discernable in the images. We find that our emulsions are stabilised on experimental time scales by interfacial particles and that they are likely to have bimodal droplet-size distributions. We attribute the latter to coalescence together with creaming being the main coarsening mechanism during the late stages of emulsification and we support this claim with (direct) confocal-microscopy observations. In addition, our results imply that the observed droplets emerge from particle-promoted nucleation, possibly followed by a free-growth regime. Finally, we argue that creaming strongly affects droplet growth during the early stages of emulsification. Future investigations could clarify the link between quench conditions and resulting microstructure, paving the way for tailor-made particle-stabilised emulsions from binary liquids.Comment: http://iopscience.iop.org/0953-8984/22/45/455102

    Walking in Sync: Two is Company, Three's a Crowd.

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    Eventual gait synchronization between two individuals while walking and talking with each other has been shown to be an indicator of agreeableness and companionship. The inferred physical signal from this subconscious phenomenon can po-tentially be an indicator of cooperation or relation between two individuals. In this paper we investigate this effect, and whether having a third person actively engaging in the same act or conversation can reduce this synchronization level. Using high frequency accelerometer data from a ded-icated smartphone app, we perform a number of controlled experiments on a number of individuals in different group configuration. Our results bring an interesting insight: it is the non-verbal social signals such as the gaze, head orienta-tion and gestures that is the key factor in synchronization, not necessarily the number or configuration of the walkers. These early results can lead us on detecting relationships between individuals or detecting the group formation and numbers for crowd-sensing applications when only partial data is available. Categories and Subject Descriptors Human-centered computing [Ubiquitous and mobile com-puting]: Empirical studies in ubiquitous and mobile com-putin

    A new infrared band in the Interstellar and Circumstellar Clouds: C_4 or C_4H?

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    We report on the detection with the Infrared Space Observatory (ISO) of a molecular band at 57.5 microns (174 cm^{-1}) in carbon-rich evolved stars and in Sgr B2. Taking into account the chemistry of these objects the most likelihood carrier is a carbon chain. We tentatively assign the band to the nu_5 bending mode of C_4 for which a wavenumber of 170-172.4 cm^{-1} has been derived in matrix experiments (Withey et al. 1991). An alternate carrier might be C_4H, although the frequency of its lowest energy vibrational bending mode, nu_7, is poorly known (130-226 cm^{-1}). If the carrier is C_4, the derived maximum abundance is nearly similar to that found for C_3 in the interstellar and circumstellar media by Cernicharo, Goicoechea & Caux (2000). Hence, tetra-atomic carbon could be one of the most abundant carbon chain molecules in these media.Comment: 11 pages, 1 figure, accepted in ApJ Letter

    Detecting Group Formations using iBeacon Technology

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