Experiments on Roll Waves in Air-Water Pipe Flow

Experiments on air-water two phase flow in inclined pipes have been made, with emphasis on the roll wave regime. The motivation for the work is the improving of 1D flow models for multiphase pipeline transport of oil and gas mixtures. Pressure and liquid fractions are recorded in time, together with video recordings. The results show that large amplitude roll waves have associated pressure jumps across the fronts. Some implications for the flow modelling are discussed

Time-averaged MSD of Brownian motion

We study the statistical properties of the time-averaged mean-square displacements (TAMSD). This is a standard non-local quadratic functional for inferring the diffusion coefficient from an individual random trajectory of a diffusing tracer in single-particle tracking experiments. For Brownian motion, we derive an exact formula for the Laplace transform of the probability density of the TAMSD by mapping the original problem onto chains of coupled harmonic oscillators. From this formula, we deduce the first four cumulant moments of the TAMSD, the asymptotic behavior of the probability density and its accurate approximation by a generalized Gamma distribution

The effect of discrete vs. continuous-valued ratings on reputation and ranking systems

When users rate objects, a sophisticated algorithm that takes into account ability or reputation may produce a fairer or more accurate aggregation of ratings than the straightforward arithmetic average. Recently a number of authors have proposed different co-determination algorithms where estimates of user and object reputation are refined iteratively together, permitting accurate measures of both to be derived directly from the rating data. However, simulations demonstrating these methods' efficacy assumed a continuum of rating values, consistent with typical physical modelling practice, whereas in most actual rating systems only a limited range of discrete values (such as a 5-star system) is employed. We perform a comparative test of several co-determination algorithms with different scales of discrete ratings and show that this seemingly minor modification in fact has a significant impact on algorithms' performance. Paradoxically, where rating resolution is low, increased noise in users' ratings may even improve the overall performance of the system.Comment: 6 pages, 2 figure

Phonon Universal Transmission Fluctuations and Localization in Semiconductor Superlattices with a Controlled Degree of Order

We study both analytically and numerically phonon transmission fluctuations and localization in partially ordered superlattices with correlations among neighboring layers. In order to generate a sequence of layers with a varying degree of order we employ a model proposed by Hendricks and Teller as well as partially ordered versions of deterministic aperiodic superlattices. By changing a parameter measuring the correlation among adjacent layers, the Hendricks- Teller superlattice exhibits a transition from periodic ordering, with alterna- ting layers, to the phase separated opposite limit; including many intermediate arrangements and the completely random case. In the partially ordered versions of deterministic superlattices, there is short-range order (among any $N$ conse- cutive layers) and long range disorder, as in the N-state Markov chains. The average and fluctuations in the transmission, the backscattering rate, and the localization length in these multilayered systems are calculated based on the superlattice structure factors we derive analytically. The standard deviation of the transmission versus the average transmission lies on a {\it universal\/} curve irrespective of the specific type of disorder of the SL. We illustrate these general results by applying them to several GaAs-AlAs superlattices for the proposed experimental observation of phonon universal transmission fluctuations.Comment: 16-pages, Revte

Performance analysis of MIMO-SESS with Alamouti scheme over Rayleigh fading channels

Las unidades fraseológicas han estado presentes en los repertorios desde los comienzos de la lexicografía. Y no solamente en los diccionarios generales, sino también en las catalogaciones especializadas, tanto de naturaleza monolingüe como bilingüe. No obstante, siempre ha existido dificultad terminológica para la categorización de los diferentes fenómenos del discurso repetido. Si bien esto no ha sido un inconveniente para que se hayan publicado numerosas compilaciones, sobre todo de refranes en un principio, ya que en la actualidad, fundamentalmente, gracias al auge de los estudios teóricos sobre fraseología, han proliferado otras obras (algunas aplicadas a la glosodidáctica, dada su importancia hoy en día) en las que se da cabida con mayor frecuencia a enunciados de valor específico y a locuciones; en unas ocasiones, ahondando en el origen que les dio entidad y, en otras, estableciendo etiquetados precisos que hasta el momento solían estar ausentes, pero con la finalidad, al fin y al cabo, de desentrañar el sentido, dada la escasa deducibilidad que presentan estas secuencias fijadas por la simple suma de sus elementos constitutivos. Un análisis de estos repertorios a través de los siglos, es, por tanto, el objetivo de este trabajo.Since the beginning of lexicography, phraseological units have been included in repertoires; not only in general dictionaries, but also in monolingual and bilingual specialized catalogues. However, there have always been terminological difficulties for classifying various phenomena of repeated speech. Although this has not been inconvenient for publishing many compilations of sayings, especially at the beginning, because nowadays they frequently include utterances with precise value and idioms, mainly due to the rise of theoretical studies on phraseology (some applied to ASL Linguistics, given its importance today). In them, sometimes, the origin of the phraseological unit is included and, in others, accurate labels that were absent before are determined in order, finally and ultimately, to unravel the meaning, given the reduced deductibility that these sequences present from the simple sum of their constituent elements. The objective of this work is, therefore, an analysis of these repertories throughout the centuries

Merleau-Ponty and the Measuring Body

In recent years a growing number of scholars in science studies and related fields are developing new ontologies to displace entrenched dualisms. These efforts often go together with a renewed interest in the roles played by symbolisms and tools in knowledge and being. This article brings Maurice Merleau-Ponty into these conversations, positioning him as a precursor of today’s innovative recastings of technoscience. While Merleau-Ponty is often invoked in relation to his early work on the body and embodiment, this article focuses on his later work, where the investigation of perception is integrated with an ontological exploration. The resulting approach revolves around the highly original idea of the body as a standard of measurement. We further develop this idea by coining the term ‘the measuring body’, which to a greater extent than did Merleau-Ponty accentuates the relative autonomy of symbolisms and tools and their capacity to decentre the perceiving body

Reciprocal relations between workplace bullying, anxiety and vigor: A two-wave longitudinal study

Background and Objectives: Workplace bullying has been classified as an extreme social stressor in work contexts and has been repeatedly linked to several negative consequences. However, little research has examined reversed or reciprocal relations of bullying and outcomes. Design: We conducted a two-wave longitudinal study with a time lag of six months. Methods: The study sample consisted of 348 employees of the Spanish workforce. The present study examined longitudinal relationships between workplace bullying, psychological health, and well-being. On the basis of conservation of resources theory, we hypothesized that we would find reciprocal relations among study variables over time. Results: Results of cross-lagged structural equation modeling analyses supported our hypotheses. Specifically, it was found that Time 1 (T1) workplace bullying was negatively related to Time 2 (T2) vigor and positively related to T2 anxiety. Additionally, T1 anxiety and vigor had an effect on T2 workplace bullying. Conclusions: Overall, these findings support the validity of the theoretical models postulating a reciprocal bullying–outcome relationship, rather than simple one-way causal pathways approaches