MOTION OF A LARGE OBJECT IN A 2D BUBBLING FLUIDIZED BED

The motion of a large object in a bubbling fluidized bed is experimentally studied using digital image analysis. A wide range of fluidized bed applications involves the motion of large objects within the bed, such objects being reactants, catalysts, agglomerates, etc. The experiments were run in a 2D bubbling fluidized bed with glass spheres as bed material. The object motion is measured using tracking techniques, while independent measurements of the dense phase velocity (using PIV) and bubble velocity were carried out. The effect of the excess gas velocity on the object motion was also analyzed. It is generally accepted that objects with densities in a range around the bed density will describe sinking-rising cycles throughout the whole bed, where the sinking motion is similar to that of the dense phase, and the rising motion is composed of a number of sudden jerks or jumps, as a result of the raising effect of passing bubbles. This work characterized the circulation patterns of an object with a density similar to that of the bed material, but much larger in size. A comparison between the object rising motion and the local bubble motion provided evidence for the study of the bubble ability to raise the object, depending on the bubble velocity and size. A comparison between the object sinking motion and the dense phase motion served to analyze the minor effect of buoyancy forces over the object sinking motion. Finally, the combined effects of the maximum attained depth and the number of jerks in the circulation time is studied, with some insight in the multiple-jerks phenomenon

Throughflow Velocity Crossing the Dome of Erupting Bubbles in 2-D Fluidized Beds

A new non-intrusive method for measuring the throughflow velocity crossing the dome of erupting bubbles in freely bubbling 2-D fluidized beds is presented. Using a high speed video-camera, the dome acceleration, drag force and throughflow velocity profiles are obtained for different experiments, varying the superficial gas velocity. The acceleration profiles show greater values in the dome zone where the gravity component is negligible. The drag force and the throughflow velocity profiles show a uniform value in the central region of the dome (40 deg \u3c \u3c 140 deg) and the total throughflow increases with the superficial gas velocity

Hydrodynamic Characteristics of a Fluidized Bed with Rotating Distributor

The performance of a novel rotating distributor fluidized bed is presented. The pressure drop and the standard deviation of pressure fluctuations, σp, were used to find the minimum fluidization velocity, Umf, and to characterize the quality of fluidization at different rotational speeds of the distributor plate. Experiments were conducted in the freely bubbling regime in a 0.19 m i.d. fluidized bed, operating with Group B particles according to Geldart’s classification. A decrease in Umf is observed when the rotational speed increases. Frequency analysis of pressure fluctuations shows that fluidization can be controlled by the adjustable rotational speed, at several excess gas velocities

Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS

The AMADEUS system is an integral part of the ANTARES neutrino telescope in the Mediterranean Sea. The project aims at the investigation of techniques for acoustic neutrino detection in the deep sea. Installed at a depth of more than 2000m, the acoustic sensors of AMADEUS are based on piezo-ceramics elements for the broad-band recording of signals with frequencies ranging up to 125kHz. AMADEUS was completed in May 2008 and comprises six "acoustic clusters", each one holding six acoustic sensors that are arranged at distances of roughly 1m from each other. The clusters are installed with inter-spacings ranging from 15m to 340m. Acoustic data are continuously acquired and processed at a computer cluster where online filter algorithms are applied to select a high-purity sample of neutrino-like signals. 1.6 TB of data were recorded in 2008 and 3.2 TB in 2009. In order to assess the background of neutrino-like signals in the deep sea, the characteristics of ambient noise and transient signals have been investigated. In this article, the AMADEUS system will be described and recent results will be presented.Comment: 7 pages, 8 figures. Proceedings of ARENA 2010, the 4th International Workshop on Acoustic and Radio EeV Neutrino Detection Activitie

Measurement of Atmospheric Neutrino Oscillations with the ANTARES Neutrino Telescope

The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximum mixing, a mass difference of $\Delta m_{32}^2=(3.1\pm 0.9)\cdot 10^{-3}$ eV$^2$ is obtained, in good agreement with the world average value.Comment: 9 pages, 5 figure

The Emotional and Attentional Impact of Exposure to One's Own Body in Bulimia Nervosa: A Physiological View

Background: Body dissatisfaction is the most relevant body image disturbance in bulimia nervosa (BN). Research has shown that viewing one's own body evokes negative thoughts and emotions in individuals with BN. However, the psychophysiological mechanisms involved in this negative reaction have not yet been clearly established. Our aim was to examine the emotional and attentional processes that are activated when patients with BN view their own bodies. Method: We examined the effects of viewing a video of one's own body on the physiological (eye-blink startle, cardiac defense, and skin conductance) and subjective (pleasure, arousal, and control ratings) responses elicited by a burst of 110 dB white noise of 500 ms duration. The participants were 30 women with BN and 30 healthy control women. The experimental task consisted of two consecutive and counterbalanced presentations of the auditory stimulus preceded, alternatively, by a video of the participant's own body versus no such video. Results: The results showed that, when viewing their own bodies, women with BN experienced (a) greater inhibition of the startle reflex, (b) greater cardiac acceleration in the first component of the defense reaction, (c) greater skin conductance response, and (d) less subjective pleasure and control combined with greater arousal, compared with the control participants. Conclusion: Our findings suggest that, for women with BN, peripheral-physiological responses to self-images are dominated by attentional processes, which provoke an immobility reaction caused by a dysfunctional negative response to their own body.The present research was supported by grants from the Spanish Ministry of Economy and Competitiveness [PSI2009-08417 and PSI2012-31395]. P.P. was supported by grants from the Spanish Ministry of Science and Innovation and University Jaume I [ECO2011-23634, P1-1B2012-27, and JCI-2010-06790]

A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000

The Challenge of Regulation in a Minimal Photoautotroph: Non-Coding RNAs in Prochlorococcus

Prochlorococcus, an extremely small cyanobacterium that is very abundant in the world's oceans, has a very streamlined genome. On average, these cells have about 2,000 genes and very few regulatory proteins. The limited capability of regulation is thought to be a result of selection imposed by a relatively stable environment in combination with a very small genome. Furthermore, only ten non-coding RNAs (ncRNAs), which play crucial regulatory roles in all forms of life, have been described in Prochlorococcus. Most strains also lack the RNA chaperone Hfq, raising the question of how important this mode of regulation is for these cells. To explore this question, we examined the transcription of intergenic regions of Prochlorococcus MED4 cells subjected to a number of different stress conditions: changes in light qualities and quantities, phage infection, or phosphorus starvation. Analysis of Affymetrix microarray expression data from intergenic regions revealed 276 novel transcriptional units. Among these were 12 new ncRNAs, 24 antisense RNAs (asRNAs), as well as 113 short mRNAs. Two additional ncRNAs were identified by homology, and all 14 new ncRNAs were independently verified by Northern hybridization and 5′RACE. Unlike its reduced suite of regulatory proteins, the number of ncRNAs relative to genome size in Prochlorococcus is comparable to that found in other bacteria, suggesting that RNA regulators likely play a major role in regulation in this group. Moreover, the ncRNAs are concentrated in previously identified genomic islands, which carry genes of significance to the ecology of this organism, many of which are not of cyanobacterial origin. Expression profiles of some of these ncRNAs suggest involvement in light stress adaptation and/or the response to phage infection consistent with their location in the hypervariable genomic islands

Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.

Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited