Dynamics of a tunable superfluid junction

We study the population dynamics of a Bose-Einstein condensate in a double-well potential throughout the crossover from Josephson dynamics to hydrodynamics. At barriers higher than the chemical potential, we observe slow oscillations well described by a Josephson model. In the limit of low barriers, the fundamental frequency agrees with a simple hydrodynamic model, but we also observe a second, higher frequency. A full numerical simulation of the Gross-Pitaevskii equation giving the frequencies and amplitudes of the observed modes between these two limits is compared to the data and is used to understand the origin of the higher mode. Implications for trapped matter-wave interferometers are discussed.Comment: 8 pages, 7 figures; v3: Journal reference added, minor changes to tex

Introduction of the Circular Economy to Expanded Polystyrene Household Waste: A Case Study From an Ecuadorian Plastic Manufacturer

[Abstract] Transition towards a more sustainable society is a complex task. The depletion of natural resources and waste generation cannot be sustained indefinitely, i.e. as waste increases, local landfills keep growing and land availability reduces. The introduction of circular economy in effective household solid waste management practices should be considered especially for third world countries, such as Ecuador. In this context, plastic recycling is an important step, particularly the case of expanded polystyrene containers that currently are single-use only and later end up in local landfills. This paper presents a methodology for recycling Expanded Polystyrene by means of a case study from an Ecuadorian Plastic Manufacturer. First, the manufacture of resin from post-consume EPS containers was demonstrated possible by the manufacturer. Second, results show that using 30% of post-consume resin in the mix produce satisfactory laboratory results and operational recycled containers.The authors would like to thank Marco Roche, Eng.; Technical Manager of Plásticos del Litoral S.A. (PLASTLIT) for its involvement and compromise in this project. This paper is supported by the National Secretary of Superior Education, Science, Technology and Innovation (SENESCYT) – INEDITA program, project “Characterization of urban household waste in Guayaquil for the classification of plastic and organic waste and reuse in local industry

Introduction

May you live in interesting times, runs the legendary Chinese curese. These are interesting times: almost anything can happen except a return to the delicate but enduring balance between two blocs that marked international relations for nearly half a century after World War II. The possibilities include nuclear war, not in the form of the long-feared mutual destruction of the Soviet Union and the United States, but as a last resort in the course of escalating regional conflicts in the Middle East or South Asia. In the aftermath of the 1991 Gulf War, United Nations inspectors found evidence of strong steps toward the production of nuclear weapons in Iraq, a country whose leaders did not hesitate to rain missiles on noncombatant Israel during their struggle to hold Kuwait; the same science is available to many other small, rich despots throughout the world. While the chances that two of the world\u27s largest countries would annihilate each other simultaneously have surely receded, the risk of nuclear war has by no means vanished

Circular Economy of Expanded Polystyrene Container Production: Environmental Benefits of Household Waste Recycling Considering Renewable Energies

[Abstract] Plastic industry is ubiquitous worldwide, and the generation of “plastic waste” has been steadily increasing to the point of being considered a high impact pollutant. The expanded polystyrene (EPS) plastic industry aware of the issue is interested on trying recycling post-consumer material. Through a recent study made in an alliance between the private sector and the academy, the feasibility of the EPS “mechanical” recycling was proven; therefore, a possible solution through a circular economy model. The aim of the present paper was to investigate the potential environmental impacts avoided by the circular economy scenario previously developed, through a life cycle assessment (LCA) performed for the city of Guayaquil, where 64% of all the plastic manufacturing industries in the country are located. The entire life cycle of 1.00 kg of 5 × 5 inch. food containers were assessed from the production stage until its end-of-life stage: focusing on three different valorization paths, circular economy closed-loop (container-to-container) proposal with electricity share of 2019 and another with the 2027 future one, and traditional linear economy (container-to-landfill). Results showed that the scenario C that considers the recycling of post-consumer EPS waste and the electricity share proposed for 2027 have lower impacts in 14 out of 16 categories, in specific for the Land use (−31%), Ozone Depletion (−28%), Acidification (−24%) and Terrestrial and Marine Eutrophication (−21%). These results strongly suggest that the recycling of these kind of plastic waste could benefit the environment greatly

Open-circuit dissolution of platinum from the cathode in polymer electrolyte membrane water electrolysers

Platinum is the state-of-the-art catalyst for hydrogen evolution in polymer electrolyte membrane (PEM) water electrolysers; however, its stability has only been characterized to a limited extent in situ. This study measures platinum dissolving from the cathode during intermittent operation of a 3-electrode PEM electrolyser cell, using a differential pulse voltammetry technique that provided detection limits for platinum of less than 2 ng L−1. Water samples were periodically taken during on-off current cycling, and during periods of open-circuit voltage (OCV) platinum dissolution was detected when the cathode potential rose above 0.85 V NHE due to diffusion of oxygen from the anode. This reached a maximum dissolution rate at the highest cathode potential of 1.02 V NHE, and gradually decayed over a 90 h period. The average total amount of platinum dissolved per 90 h OCV period was estimated to be 152 ng cm−2 or 0.005% of the initial electrode catalyst mass. The dissolution mechanism was predicted to be the same as that occurring in PEM fuel cell cathodes, although being kinetically hindered in PEM electrolysers by the slow diffusion of oxygen from the anode to the cathode

Shifts in Global Security Policies: Why They Matter for the South

The global security order has been evolving since 1989, led initially by the USA to expand its post?1945 order in Europe to the rest of the world but propelled as well by competition and debates within that post?Second World War alliance, as collective victors in the Cold War, about how to define a new international order. This article identifies three US policies that began this restructuring; their parallel redefinitions of security, and the tensions provoked by this agenda and its consequences, both within the ‘North’, replacing the ‘West’, between North and ‘South’, replacing the‘East’and the resulting multiple opportunities for alternative political coalitions, North against South, between North and South, and within the South, that have yet to play themselves out fully. The resulting fluidity has not yet stabilised into a new international security order

Rapid Preparation of Geometrically Optimal Battery Electrode Samples for Nano Scale X-ray Characterisation

Rechargeable lithium-based batteries are one of the key enabling technologies driving the shift to renewable energy, and research into novel technologies has intensified to meet growing demands in applications requiring higher energy and power density. The mechanisms behind battery degradation can be investigated across multiple length-scales with X-ray imaging methods; at the nanoscale severe constraints are imposed on sample size in order to obtain adequate signal to noise. Here, we present a novel lasermilling technique to prepare geometrically optimal samples for X-ray nano-tomography. Advantages of this technique include significantly reduced sample preparation time, and a suitable geometry for mosaic acquisition, enabling a larger field of view to be captured at high spatial resolution, thus improving statistics. The geometry of the resulting electrode remains highly suitable for nano-tomography, and yet permits in situ and operando experiments to be carried out on standard electrode coatings, providing new insights into transient phenomena whilst closely mimicking standard electrochemical cells

Research encounters, reflexivity and supervision

Reflexivity in qualitative and ethnographic social science research can provide a rich source of data, especially regarding the affective, performative and relational aspects of interviews with research subjects. This paper explores by means of three case examples different ways of accessing and using such reflexivity. The examples are drawn from an empirical psycho-social study into the identity transitions of first-time mothers in an inner-city multicultural environment. Fieldnotes and supervision were used to engage with researcher subjectivity, to enhance the productive use of reflexivity and to address the emotional work of research. The methodology of the supervision was psychoanalytic, in its use of a boundaried frame and of psychoanalytic forms of noticing oneself, of staying engaged emotionally as well as creating a reflective distance. The examples illustrate how this can enhance the knowledge gained about the research subjects

The dietary impact of the Norman Conquest: A multiproxy archaeological investigation of Oxford, UK

Archaeology has yet to capitalise on the opportunities offered by bioarchaeological approaches to examine the impact of the 11th-century AD Norman Conquest of England. This study utilises an integrated multiproxy analytical approach to identify and explain changes and continuities in diet and foodways between the 10th and 13th centuries in the city of Oxford, UK. The integration of organic residue analysis of ceramics, carbon (δ13C) and nitrogen (δ15N) isotope analysis of human and animal bones, incremental analysis of δ13C and δ15N from human tooth dentine and palaeopathological analysis of human skeletal remains has revealed a broad pattern of increasing intensification and marketisation across various areas of economic practice, with a much lesser and more short-term impact of the Conquest on everyday lifestyles than is suggested by documentary sources. Nonetheless, isotope data indicate short-term periods of instability, particularly food insecurity, did impact individuals. Evidence of preferences for certain foodstuffs and cooking techniques documented among the elite classes were also observed among lower-status townspeople, suggesting that Anglo-Norman fashions could be adopted across the social spectrum. This study demonstrates the potential for future archaeological research to generate more nuanced understanding of the cultural impact of the Norman Conquest of England, while showcasing a method which can be used to elucidate the undocumented, everyday implications of other large-scale political events on non-elites