Implementation of a flexible and modular multiphase framework for the analysis of surface-tension-driven flows based on a LS-VOF approach

The mathematical modelling and numerical simulation of multi-phase flows are both a demanding and highly complex exercise. In typical problems with industrial relevance, the fluids are often in non-isothermal conditions and interfacial phenomena are a relevant part of the problem. A number of effects due to the presence of temperature differences must be adequately taken into account to make the results of numerical simulations consistent and realistic. Moreover, in general, gradients of surface tension at the interface separating two liquids are a source of numerical issues that can delay (and even prevent completely in some circumstances) the convergence of the solution algorithm. Here, we propose a fundamental and concerted approach for the simulation of the typical dynamics resulting from the presence of a dispersed phase in an external matrix in nonisothermal conditions based on the modular computer-aided design, modelling, and simulations capabilities of the OpenFOAM environment. The resulting framework is tested against the migration of a droplet induced by thermocapillary effects in the absence of gravity. The simulations are fully three-dimensional and based on an adaptive mesh refinement (AMR) strategy. We describe in detail the countermeasures taken to circumvent the problematic issues associated with the simulation of this kind of flows

Modulating proactive cognitive control by reward:Differential anticipatory effects of performance contingent and non-contingent rewards

The present study investigated the influences of two different forms of reward presentation in modulating cognitive control. In three experiments, participants performed a flanker task for which one-third of trials were precued for a chance of obtaining a reward (reward trials). In Experiment 1, a reward was provided if participants made the correct response on reward trials, but a penalty was given if they made an incorrect response on these trials. The anticipation of this performance-contingent reward increased response speed and reduced the flanker effect, but had little influence on the sequential modulation of the flanker effect after incompatible trials. In Experiment 2, participants obtained a reward randomly on two-thirds of the precued reward trials and were given a penalty on the remaining one-third, regardless of their performance. The anticipation of this non-contingent reward had little influence on the overall response speed or flanker effect, but reduced the sequential modulation of the flanker effect after incompatible trials. Experiment 3 also used performance non-contingent rewards, but participants were randomly penalized more often than they were rewarded; non-contingent penalty had little influence on the sequential modulation of the flanker effect. None of the three experiments showed a reliable influence of the actual acquisition of rewards on task performance. These results indicate anticipatory effects of performance-contingent and non-contingent rewards on cognitive control with little evidence of aftereffects

Patterns of Non-injection Drug Use Associated with Injection Cessation among Street-Involved Youth in Vancouver, Canada

Although abstinence from drug use is often a key goal of youth substance use treatment, transitioning to less harmful routes and types of drug use is desirable from both a clinical and public health perspective. Despite this, little is known about the trajectories of youth who inject drugs including changes in patterns of non-injection drug use. The At-Risk Youth Study (ARYS) is a longitudinal cohort of street-involved youth who use drugs in Vancouver, Canada. We used linear growth curve modeling to compare changes in non-injection drug use among participants who ceased injecting drugs for at least one 6-month period between September 2005 and May 2015 to matched controls who continued injecting over the same period. Of 387 eligible participants, 173 (44.7%) reported ceasing drug injection at least once. Non-injection drug use occurred during 160 (79.6%) periods of injection cessation. In adjusted linear growth curve analyses, the only non-injection drug use pattern observed to decrease significantly more than controls following injection cessation was daily crack/cocaine use (p = 0.024). With the exception of frequent crack/cocaine use, transitions out of injection drug use did not appear to coincide with increased reductions in patterns of non-injection drug use. Our findings indicate that most (80%) of the observed injection cessation events occurred in the context of ongoing substance use. Given that transitioning out of drug injection represents a significant reduction in risk and harm, efforts supporting vulnerable youth to move away from injecting may benefit from approaches that allow for ongoing non-injection drug use. &nbsp

Tsireledzani: understanding the dimensions of human trafficking in southern Africa

This report provides the first comprehensive assessment of human trafficking in South Africa. This research study was conducted by the Human Sciences Research Council (HSRC) on behalf of the 'Programme of Assistance to the South African Government to Prevent, React to Human Trafficking and Provide Support to Victims of Crime'. The programme of assistance forms part of South Africa's National Strategy to Combat Human Trafficking through prevention, response and support for victims, known as TSIRELEDZANI. The programme of assistance is being implemented by the Sexual Offences and Community Affairs (SOCA) Unit of the National Prosecuting Authority (NPA). The overall objective of South Africa?s National Strategy on Human Trafficking is to ensure full compliance with the Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children (hereafter, 'Palermo Protocol'), which supplements the United Nations Convention against Transnational Organised Crime. Compliance includes developing comprehensive legislation under-pinned by a victimcentred empowerment approach, taking full account of the Victim's Charter as well as relevant South African legislation

Decoding the Ancient Greek Astronomical Calculator Known as the Antikythera Mechanism [Letter]

The Antikythera Mechanism is a unique Greek geared device, constructed around the end of the second century bc. It is known1, 2, 3, 4, 5, 6, 7, 8, 9 that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar. Calendars were important to ancient societies10 for timing agricultural activity and fixing religious festivals. Eclipses and planetary motions were often interpreted as omens, while the calm regularity of the astronomical cycles must have been philosophically attractive in an uncertain and violent world. Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial11, 12, 13, 14 because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions9, 14, 15, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period

Inscriptions of the Antikythera Mechanism

Contents: 0. Front matter. 1. The Antikythera Mechanism Research Project: M. Allen, W. Ambrisco, M. Anastasiou, D. Bate, Y. Bitsakis, A. Crawley, M. G. Edmunds, D. Gelb, R. Hadland, P. Hockley, A. Jones, T. Malzbender, H. Mangou, X. Moussas, A. Ramsey, J. H. Seiradakis, J. M. Steele, A. Tselikas, and M. Zafeiropoulou. 1. General Preface to the Inscriptions. 4-35. 2. A. Jones. Historical Background and General Observations. 36-66. 3. Y. Bitsakis and A. Jones. The Front Dial and Parapegma Inscriptions. 68-137. 4. M. Anastasiou, Y. Bitsakis, A. Jones, J. M. Steele, and M. Zafeiropoulou. The Back Dial and Back Plate Inscriptions. 138-215. 5. Y. Bitsakis and A. Jones. 5. The Back Cover Inscription. 216-248. 6. M. Anastasiou, Y. Bitsakis, A. Jones, X. Moussas, A. Tselikas, and M. Zafeiropoulou. 6. The Front Cover Inscription. 250-297 7. Supplementary Illustrations. 298-310

Illegal aliens and demons that must be exorcised from South Africa: Framing African migrants and xenophobia in post-apartheid narratives

This article interprets narratives that have dominated the public sphere in post-apartheid South Africa, following the influx of African migrants. It uses qualitative data from personal interviews with local South Africans, excerpts from familiar political speeches and print media articles to tease out how the construction and intersection of public messages about foreigners and xenophobia have contributed to the recurrent attacks of African migrants. The article argues that although post-apartheid South Africa has become a prime migration destination, the country’s economic and psychosocial challenges have influenced the way citizens frame narratives about African migrants from other parts of the continent. These narratives are often fraught with images and metaphors that demonise and attempt to justify violence against African migrants. The article attempts to examine how the framing of such narratives provides a discursive space for understanding South Africans’ perceptions about African migrants and the multiple perspectives of xenophobia in post-apartheid South Africa