Orbital photogalvanic effects in quantum-confined structures

We report on the circular and linear photogalvanic effects caused by free-carrier absorption of terahertz radiation in electron channels on (001)-oriented and miscut silicon surfaces. The photocurrent behavior upon variation of the radiation polarization state, wavelength, gate voltage and temperature is studied. We present the microscopical and phenomenological theory of the photogalvanic effects, which describes well the experimental results. In particular, it is demonstrated that the circular (photon-helicity sensitive) photocurrent in silicon-based structures is of pure orbital nature originating from the quantum interference of different pathways contributing to the absorption of monochromatic radiation.Comment: 8 pages, 5 figures, two culumne

Gender and participation: critical reflection on Zenzeleni Networks in Mankosi, South Africa

This paper unveils the complexity of gender dynamics by reflecting on lessons learned in Zenzeleni Networks and provides a different perspective to notions of “participation” by asking “who participates and how?” The paper employs a feminist conceptual framework, particularly social constructionist theory and intersectionality, to understand women’s participation and experience, analyzing multi-layered and intersecting structural injustices that marginalize women’s choices, empowerment, scope for agency, and sense of ownership. In-depth interviews and focus group discussions gathered information from women living in Mankosi and women who are working for Zenzeleni Networks, respectively. Results show that gendered power dynamics of the community were reproduced within Zenzeleni Networks. Although women play a key role in the everyday operationalization of Zenzeleni Networks, their role has been considered part of their domestic duties, which results in misrecognition and underrepresentation of their work.CONFINE Integrated Project FIRE #288535 Telkom, Cisco and Aria Technologies via the Telkom Centre of Excellence (CoE) programme

Diversifying Future-Making Through Itinerative Design

Designed in California is a brand statement used by high-tech manufacturers to denote provenance and cachet of digital innovation and modernity. In this paper, we explore philosophically alternate design perspectives to those this statement embodies, reporting and reflecting on a long-term multi-sited project that seeks to diversify future-making by engaging communities of "emergent" users in "developing" regions. We argue that digital technologies are typically created with a design lens firmly focused on "first world" populations, assuming a base set of cultural norms, resource availabilities, and technological experience levels that do not strongly align with those of emergent users. We discuss and argue for inclusive technology design methods, present our approach, and detail indicative results and case studies as an example of the potential of these perspectives in uncovering radical innovations. Distilling findings and lessons learned, we present a methodology-itinerative design-that pivots between emergent user communities across multiple regions, driving digital innovation through the periphery of mainstream design's current remit

Walking and the social life of solar charging in rural Africa

We consider practices that sustain social and physical environments beyond those dominating sustainable HCI discourse. We describe links between walking, sociality, and using resources in a case study of community-based, solar, cellphone charging in villages in South Africa’s Eastern Cape. Like 360 million rural Africans, inhabitants of these villages are poor and, like 25% and 92% of the world, respectively, do not have domestic electricity or own motor vehicles. We describe nine practices in using the charging stations we deployed. We recorded 700 people using the stations, over a year, some regularly. We suggest that the way we frame practices limits insights about them, and consider various routines in using and sharing local resources to discover relations that might also feature in charging. Specifically, walking interconnects routines in using, storing, sharing and sustaining resources, and contributes to knowing, feeling, wanting and avoiding as well as to different aspects of sociality, social order and perspectives on sustainability. Along the way, bodies acquire literacies that make certain relationalities legible. Our study shows we cannot assert what sustainable practice means a priori and, further, that detaching practices from bodies and their paths limits solutions, at least in rural Africa. Thus, we advocate a more “alongly” integrated approach to data about practices.Web of Scienc

StreetWise: Smart Speakers vs Human Help in Public Slum Settings

This paper explores the use of conversational speech question and answer systems in the challenging context of public spaces in slums. A major part of this work is a comparison of the source and speed of the given responses; that is, either machine-powered and instant or human-powered and delayed. We examine these dimensions via a two-stage, multi-sited deployment. We report on a pilot deployment that helped refine the system, and a second deployment involving the installation of nine of each type of system within a large Mumbai slum for a 40-day period, resulting in over 12,000 queries. We present the findings from a detailed analysis and comparison of the two question-answer corpora; discuss how these insights might help improve machine-powered smart speakers; and, highlight the potential benefits of multi-sited public speech installations within slum environments. © 2019. Copyright held by the authors

Chemical analysis of pottery demonstrates prehistoric origin for high-altitude alpine dairying

The European high Alps are internationally renowned for their dairy produce, which are of huge cultural and economic significance to the region. Although the recent history of alpine dairying has been well studied, virtually nothing is known regarding the origins of this practice. This is due to poor preservation of high altitude archaeological sites and the ephemeral nature of transhumance economic practices. Archaeologists have suggested that stone structures that appear around 3,000 years ago are associated with more intense seasonal occupation of the high Alps and perhaps the establishment of new economic strategies. Here, we report on organic residue analysis of small fragments of pottery sherds that are occasionally preserved both at these sites and earlier prehistoric rock-shelters. Based mainly on isotopic criteria, dairy lipids could only be identified on ceramics from the stone structures, which date to the Iron Age (ca. 3,000 - 2,500 BP), providing the earliest evidence of this practice in the high Alps. Dairy production in such a marginal environment implies a high degree of risk even by today’s standards. We postulate that this practice was driven by population increase and climate deterioration that put pressure on lowland agropastoral systems and the establishment of more extensive trade networks, leading to greater demand for highly nutritious and transportable dairy products

Polyurethane scaffold with in situ swelling capacity for nucleus pulposus replacement

Nucleus pulposus (NP) replacement offers a minimally invasive alternative to spinal fusion or total disc replacement for the treatment of intervertebral disc (IVD) degeneration. This study aimed to develop a cytocompatible {NP} replacement material, which is feasible for non-invasive delivery and tunable design, and allows immediate mechanical restoration of the IVD. A bi-phasic polyurethane scaffold was fabricated consisting of a core material with rapid swelling property and a flexible electrospun envelope. The scaffold was assessed in a bovine whole {IVD} organ culture model under dynamic load for 14 days. Nucleotomy was achieved by incision through the endplate without damaging the annulus fibrosus. After implantation of the scaffold and in situ swelling, the dynamic compressive stiffness and disc height were restored immediately. The scaffold also showed favorable cytocompatibility for native disc cells. Implantation of the scaffold in a partially nucleotomized {IVD} down-regulated catabolic gene expression, increased proteoglycan and type {II} collagen intensity and decreased type I collagen intensity in remaining {NP} tissue, indicating potential to retard degeneration and preserve the {IVD} cell phenotype. The scaffold can be delivered in a minimally invasive manner, and the geometry of the scaffold post-hydration is tunable by adjusting the core material, which allows individualized design. Keywords : Intervertebral disc degeneratio

High impact: early pastoralism and environmental change during the Neolithic and Bronze Age in the Silvretta Alps (Switzerland/Austria) as evidenced by archaeological, palaeoecological and pedological proxies

The beginnings of the continuous human presence and of pastoral activities in the high mountainous region of Central Europe have recently become a frequently discussed topic in both archaeology and palaeoecology. In extreme environments such as the high Alpine main ridge and adjacent areas, highly adaptive subsistence strategies were required to exploit natural resources available in the subalpine and alpine zones. Such strategies were determined by changing environmental, social, and economic conditions. To investigate the relationships between settlement dynamics, human impact, and Holocene climatic changes, we studied the valleys of the Silvretta Massif in the central Eastern Alps between the Paznaun(Austria) and Lower Engadine valleys (Switzerland). We are presenting new archaeological, palaeoecological, and pedological evidence of continuous human activities from the Early Neolithic Period to the Bronze Age (~ 5,500–800 BC). This evidence sheds new light on the beginnings of intensified human impact on the high mountainous landscape, i.e. activities beyond Mesolithic hunting along the timberline. Archaeological data suggest a shift in subsistence strategies from hunting to herding at the end of the Neolithic Period (~ 2,800–2,500 BC). While palaeoecological data confirm this trend, they also indicate potentially earlier human and livestock impact through forest clearances by fire and grazing from about 4,200 BC onwards. In addition to archaeological sites and peat bogs, soils in high-altitude regions prove to be appropriate archives indicating former vegetation cover, shifts of timberline altitudes as well as disturbance of soil formation by human activity such as by slash-and-burn and by livestock grazing.Palaeobotan