1,065 research outputs found
Transmission electron microscopy investigation of segregation and critical floating-layer content of indium for island formation in InGaAs
We have investigated InGaAs layers grown by molecular-beam epitaxy on
GaAs(001) by transmission electron microscopy (TEM) and photoluminescence
spectroscopy. InGaAs layers with In-concentrations of 16, 25 and 28 % and
respective thicknesses of 20, 22 and 23 monolayers were deposited at 535 C. The
parameters were chosen to grow layers slightly above and below the transition
between the two- and three-dimensional growth mode. In-concentration profiles
were obtained from high-resolution TEM images by composition evaluation by
lattice fringe analysis. The measured profiles can be well described applying
the segregation model of Muraki et al. [Appl. Phys. Lett. 61 (1992) 557].
Calculated photoluminescence peak positions on the basis of the measured
concentration profiles are in good agreement with the experimental ones.
Evaluating experimental In-concentration profiles it is found that the
transition from the two-dimensional to the three-dimensional growth mode occurs
if the indium content in the In-floating layer exceeds 1.1+/-0.2 monolayers.
The measured exponential decrease of the In-concentration within the cap layer
on top of the islands reveals that the In-floating layer is not consumed during
island formation. The segregation efficiency above the islands is increased
compared to the quantum wells which is explained tentatively by
strain-dependent lattice-site selection of In. In addition, In0.25Ga0.75As
quantum wells were grown at different temperatures between 500 oC and 550 oC.
The evaluation of concentration profiles shows that the segregation efficiency
increases from R=0.65 to R=0.83.Comment: 16 pages, 6 figures, 1 table, sbmitted in Phys. Rev.
Unusual features in the nonlinear microwave surface impedance of Y-Ba-Cu-O thin films
Striking features have been found in the nonlinear microwave (8 GHz) surface
impedance of high-quality YBaCuO thin films with comparable
low power characteristics [ and ]. The surface resistance is found to increase,
decrease, or remain independent of the microwave field (up to 60 mT)
at different temperatures and for different samples. However, the surface
reactance always follows the same functional form. Mechanisms which may
be responsible for the observed variations in and are briefly
discussed.Comment: 4 pages, 4 figure
Incommensurate Spin Density Waves in Iron Aluminides
Neutron diffraction in Fe(Al) reveals incommensurate spin density waves (SDWs) in alloys known to be spin glasses. The wave vectors for crystals of Fe(34Al), Fe(40Al), and Fe(43Al) show n varying from 11 to 6 for →q=2π(h±1/n,k±1/n,l±1/n)/a0, where (h,k,l) and a0 characterize the parent bcc lattice of the CsCl structure. The magnetic reflections are present far above the spin-glass freezing temperatures. These SDWs keep the spins on nearest-neighbor Fe atoms close to parallel, in contrast with SDWs in Cr, which keep nearest-neighbor spins close to antiparallel
The Serums Tool-Chain:Ensuring Security and Privacy of Medical Data in Smart Patient-Centric Healthcare Systems
Digital technology is permeating all aspects of human society and life. This leads to humans becoming highly dependent on digital devices, including upon digital: assistance, intelligence, and decisions. A major concern of this digital dependence is the lack of human oversight or intervention in many of the ways humans use this technology. This dependence and reliance on digital technology raises concerns in how humans trust such systems, and how to ensure digital technology behaves appropriately. This works considers recent developments and projects that combine digital technology and artificial intelligence with human society. The focus is on critical scenarios where failure of digital technology can lead to significant harm or even death. We explore how to build trust for users of digital technology in such scenarios and considering many different challenges for digital technology. The approaches applied and proposed here address user trust along many dimensions and aim to build collaborative and empowering use of digital technologies in critical aspects of human society
Materializing digital collecting: an extended view of digital materiality
If digital objects are abundant and ubiquitous, why should consumers pay for, much less collect them? The qualities of digital code present numerous challenges for collecting, yet digital collecting can and does occur. We explore the role of companies in constructing digital consumption objects that encourage and support collecting behaviours, identifying material configuration techniques that materialise these objects as elusive and authentic. Such techniques, we argue, may facilitate those pleasures of collecting otherwise absent in the digital realm. We extend theories of collecting by highlighting the role of objects and the companies that construct them in materialising digital collecting. More broadly, we extend theories of digital materiality by highlighting processes of digital material configuration that occur in the pre-objectification phase of materialisation, acknowledging the role of marketing and design in shaping the qualities exhibited by digital consumption objects and consequently related consumption behaviours and experiences
Addicting via hashtags: How is Twitter making addiction?
Persons, substances, bodies, consumption: an ever widening process of ‘‘addicting’’ is underway in Western societies. In this article, we turn our attention to the production of addiction on the microblogging social media platform, Twitter, as an important emerging site in which the addicting of contemporary societies is also occurring. Our analysis explores two questions. First, we investigate the ways in which addiction is enacted via Twitter. How is addiction being made on Twitter? Second, we ask how the technology of Twitter itself is shaping meaning: how do the technological ‘‘affordances’’ of Twitter help constitute the kinds of addiction being materialized? While we find a multiplicity of meanings in the 140-character messages, we also find a pattern: a tendency toward extremes—addiction riven between pain and pleasure. In addition, we find significant areas of commonality between approaches and notable silences around alternatives to common understandings of addiction. We argue that the constraints on communication imposed by Twitter technology afford a ‘‘shorthand’’ of addiction that is both revealing and productive. Illuminated is the importance of addiction as a piece of cultural shorthand that draws on and simultaneously reproduces simplistic, reductive addiction objects. In concluding, we consider what these realities of addiction being enacted through Twitter can tell us about contemporary conditions of possibility for drug use in society and for individual subjectivities and experiences
Exploring Appropriation of Global Cultural Rituals
Adolescents, as a consequence of identification with popular culture, have been described as having homogenous consumption patterns. More recently, however, it has been recognised that ‘glocalisation’ (global practices reworked to fit local contexts) affords an opportunity for differentiation. This paper considers a recent UK phenomenon, namely that of the US high school prom, and seeks to explore the ways in which this ritual has been adopted or adapted as part of youth culture. The method employed here was mixed methods and included in-depth interviews with those who attended a prom in the last three years as well as a questionnaire distributed amongst high school pupils who were anticipating a high school prom. The findings illustrate that the high school prom in the UK is becoming increasingly integrated into the fabric of youth culture although, depending on the agentic abilities employed by the emerging adults in the sample, there is differing appropriation of this ritual event particularly in relation to attitudes towards and motivations for attending the prom. A typology of prom attendees is posited. This paper contributes to our understanding of this practice in a local context
Culinary communication practices:The role of retail spaces in producing field-specific cultural capital
Purpose: This chapter explores the practices underpinning the production of field-specific cultural capital at festivals, understood here as retail spaces that gather a plethora of distinct market actors. Methodology/Approach: This research presents evidence from an ethnographic study employing an interpretative paradigm and multiple data collection processes. The empirical research has been undertaken in the context of food festivals associated with the foodie taste regime. Findings: Three categories of practices that play a role in the production of field-specific cultural capital, namely representational, exchange, and experiential practices, are presented. Practical Implications: Our chapter provides recommendations for food festival organizers and participants who need to improve their practices when facing challenges such as increasing international competition and costs or declining sponsorship. Research Limitations/Implications: This chapter contributes to the growing body of field-level market analysis by showing how practices enabled by complex retail spaces contribute to the production of field-specific cultural capital. However, this chapter is limited by its focus on food festivals. Originality/Value of the Paper: This chapter theorizes how practices enable the acceleration and diversification of field-specific capital exchange, as well as its integration with other forms of capital
How Can Consumer Research Contribute to Increased Understanding of Tourist Experiences? A Conceptual Review
Author's accepted version (postprint).This is an Accepted Manuscript of an article published by Taylor & Francis in Scandinavian Journal of Hospitality and Tourism on 24/07/2015, available online: http://wwww.tandfonline.com/10.1080/15022250.2015.1065591
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