Evaporation of a packet of quantized vorticity

A recent experiment has confirmed the existence of quantized turbulence in superfluid He3-B and suggested that turbulence is inhomogenous and spreads away from the region around the vibrating wire where it is created. To interpret the experiment we study numerically the diffusion of a packet of quantized vortex lines which is initially confined inside a small region of space. We find that reconnections fragment the packet into a gas of small vortex loops which fly away. We determine the time scale of the process and find that it is in order of magnitude agreement with the experiment.Comment: figure 1a,b,c and d, figure2, figure

Can Cash Transfer Programmes Have 'Transformative' Effects?

Cash transfers (CTs), for all their evident success in relieving poverty, have been criticised for failing to incorporate transformative elements into their programme design. In recent years changes have been introduced into the design of CT programmes that go some way towards addressing this concern. This article critically engages the meaning of transformative social protection and introduces a collection of papers that examine whether and under what conditions cash transfers can be ‘transformative’. Among the issues addressed are whether CTs can be catalysts leading to positive changes, material, subjective and relational in the lives of poor people; what are the social effects of CTs for beneficiaries, their households and communities; and can they foster horizontal relationships within communities and vertical relationship with the state through developing forms of social accountability and citizenship engagement

Reconnection of superfluid vortex bundles

Using the vortex filament model and the Gross Pitaevskii nonlinear Schroedinger equation, we show that bundles of quantised vortex lines in helium II are structurally robust and can reconnect with each other maintaining their identity. We discuss vortex stretching in superfluid turbulence and show that, during the bundle reconnection process, Kelvin waves of large amplitude are generated, in agreement with the finding that helicity is produced by nearly singular vortex interactions in classical Euler flows.Comment: 10 pages, 7 figure

Polarization of superfluid turbulence

We show that normal fluid eddies in turbulent helium II polarize the tangle of quantized vortex lines present in the flow, thus inducing superfluid vorticity patterns similar to the driving normal fluid eddies. We also show that the polarization is effective over the entire inertial range. The results help explain the surprising analogies between classical and superfluid turbulence which have been observed recently.Comment: 3 figure

Developing and Assessing Respect for Human Dignity in College Students

Academic institutions are now expected to engage in developing and assessing learning outcomes; however, responsibility outcomes, such as respect for human dignity (RFHD), can be particularly challenging. As part of our Biopsychology course and Sensation and Perception course over the past decade, we applied the scientist-educator model of learning and drew from the literature on prejudice reduction to develop our RFHD interventions, which involved face-to-face interactions with others who had sensory deficits or brain/spinal cord injuries. We iteratively created two pre-post measures to assess development of different aspects of RFHD: a Behavioral Tendencies Questionnaire and a 4-Factor RFHD Model Questionnaire. Recently, we modified the intervention and the assessments for adoption in our Class, Race, and Ethnicity in Society course. This paper reports findings from these three courses and a control course in engineering (n = 153). Findings support our two sets of hypotheses, regarding 1) the efficacy of the assessments to capture different likelihoods for interacting with others targeted by the interventions and changes over time in these factors, and 2) positive effects of the face-to-face intervention activities. This study demonstrates RFHD can be developed and assessed in a college course and provides new assessments for RFHD that are easily modified for a variety of types of others (e.g., individuals who are homeless versus blind or of a particular race). Click here to read the corresponding ISSOTL blog post

Valuing the Expertise of Mobile Herders in Arid South Africa--A Photographic Essay

Pastoralism has been practiced for millennia in numerous ecosystems across the world. Throughout history, pastoral systems and in particular herding have been replaced by the commercialization of livestock production, which essentially made herders redundant in many sub-Sahara countries resulting in job losses. Herding is however still practiced in many countries, but the essential role of the herder is in many instances snubbed upon and disregarded as trivial work, hence their low social standing within the community. Literature however indicates that herding does offer many benefits over commercial paddock systems e.g. improving rural livelihoods, reviving customary practice, reducing stock theft, reducing predation and improving biodiversity management. The contribution of herders is often underestimated, even within livestock-keeping communities, but is in fact much more complicated and they do far more than meets the eye. This paper (in the form of a photo essay) is an attempt not only to give a human face to herders through a series of photographic images, but to highlight particular activities of herders in the semi-arid Namaqualand region of South Africa. The images show the complexity of herding, which is in fact an artisanal task. It depicts herders in their daily activities as botanists with an in depth botanical knowledge including, taxonomy, phytochemistry, nutritional value, toxicity, cultural, and ritual value. It also depicts herders as midwives during lambing season, practicing nursing, and shows the interaction with their guarding dogs. Furthermore, the images illustrate the gender identity with shepherdesses functioning in an extremely harsh semi-arid landscape. It also shows the interaction between herders at the water point which acts as the gathering point for the exchange of knowledge between these artisans. These results show that the value of herders in dryland farming systems deserve more recognition and they should be key players in policy development

Specific heat of the Kelvin modes in low temperature superfluid turbulence

It is pointed out that the specific heat of helical vortex line excitations, in low temperature superfluid turbulence experiments carried out in helium II, can be of the same order as the specific heat of the phononic quasiparticles. The ratio of Kelvin mode and phonon specific heats scales with L_0 T^{-5/2}, where L_0 represents the smoothed line length per volume within the vortex tangle, such that the contribution of the vortex mode specific heat should be observable for L_0 = 10^6-10^8 cm^{-2}, and at temperatures which are of order 1-10 mK.Comment: 3 pages, 1 figur

Nutritional Quality of Available Forages for Small Stock during a Drought in an Arid Pastoral Landscape in South Africa

This study aimed to assess the nutritional quality of the available forage species during a drought in an arid pastoral system in South Africa. Forage biomass was collected during the wet and dry seasons whilst following livestock herds consisting of boer goats, swakara sheep and mixed breed sheep, in both the summer and winter rainfall regions of the pastoral system. Mineral nutrient content in the plant species revealed that the forages utilized by the livestock generally contained adequate concentrations of Mg, Ca, Na, and K to meet the dietary requirements of the small stock in both the winter and summer rainfall areas. Zinc concentrations in more than half of the forages sampled in the summer rainfall area, during both wet and dry seasons, however, were below the required concentrations for small stock. When considering all plant species utilised, the diets were generally adequate in all mineral nutrients. However, none of the forage species contained sufficiently high concentrations of protein to meet the minimum requirements for small stock. These findings therefore show that pastoralists have to deal with chronic low levels of protein during droughts, and their inability to purchase supplementary feed, or to cultivate fodder crops, or temporary emigrate out of the system puts their livelihoods at high risk to climate change