1,196 research outputs found
Henri Mitterand, Le roman à l’œuvre – genèse et valeurs
Henri Mitterand, Le roman à l’œuvre – genèse et valeurs
Designing Virtual Reality Headsets to Prevent Myopia
Virtual reality (VR) headsets are currently being designed and developed for consumer use. Simultaneously, the rate of myopic development is increasing around the world. Little is known about the connection between the proximity viewing in VR headsets and myopic development. The past three decades of research have indicated a probable relationship between near-work activities and the development of myopia. Based on the current research, VR headsets do not appear to induce a strong myopiagenic stimulus on axial elongation. This paper offers a potential explanation and proposes a set of design recommendations for designing future VR headsets that prevent myopia
Implementing Non-Invasive Prenatal Testing (NIPT): Perspectives of patients and professionals
Cornel, M.C. [Promotor]Henneman, L. [Copromotor]Pajkrt, E. [Copromotor
Investigation of magnetization structures in ferromagnetic and superconducting samples by magnetic force microscopy
Even though the phenomenon of magnetic ordering in solids was already known to the
ancient Greek, the microscopic understanding of why certain materials show magnetic
order dates from this century. In particular, even though some form of magnetic domains
was already expected by Weiss when he formulated his theory of Ferromagnetic
ordering in 1907, direct experimental evidence of their existence was only provided
in 1931 by measurements of v. Hámod and Thiessen and Bitter. In these experiments,
the domain structure was determined by the imaging of small magnetic particles
that decorate regions with high magnetic stray fields. This decoration is due to the interaction
force between these particles and the sample stray field. Interestingly enough,
the reason why the domains were formed was still unclear, and was only clarified in
1935 by Landau and Lifschitz.
The phenomenon of Superconductivity on the other hand, was discovered much
more recently in 1911 by Kamerlingh Onnes. After its discovery, it took until 1933, when
Meissner and Ochsenfeld found that superconductors are ideal diamagnets, repelling
the magnetic flux from their inside, even if the field is applied before the superconductor
becomes superconductive. Again, the existence of domains was first predicted from the
theory published by Landau in 1937, but it took until the fifties before the first magnetic
flux structures in superconductors were imaged, again using the decoration technique.
Thus, even though the theoretical understanding of the domains in ferromagnets
and superconductors evolved almost simultaneously, the first direct observation of the
latter took 23 years longer, which was probably due to the experimental diffculties of
studying superconductors.
Magnetic force microscopy (MFM) is a relatively new technique for imaging these
magnetization structures. It combines the properties of the decoration technique (the
contrast formation is due the magnetic interaction between the stray field of the sample
and a small magnetic particle) with the properties of the scanning force microscopy
technique developed by Binnig, Quate and Gerber (measuring the interaction be-
tween the particle and the sample as a function of position through the deflection of
a cantilever beam). The first MFM measurements were made on ferromagnets.
Again, the first observation of magnetization structures in superconductors took somewhat
longer, until 1994. Nowadays with time and effort, the experimental diffculties
of working with MFM at low temperatures have been diminished by the development of
better instruments and improved measurement methods. The measurements presented
in this thesis were made with such an instrument, the design of which is discussed in
chapter 2.
Compared to other types of magnetic imaging,2 the advantages of the MFM technique
are a high spatial resolution imaging and relatively low requirements for sample
preparation. Another, unique property of the MFM is that it can be used as a tool for
determining the response of the sample to a local applied field and for modifying the
sample. One of the main disadvantages of the MFM until now has been the diffculty
to interpret the measured signal. In recent years, the improvement in the quality of
the instrument and the subsequent improvement of the measurement quality has allowed
the development of procedures that allow the quantitative interpretation of the
measured contrast. The methods developed for quantitative evaluation of the MFM
measurements as part of this thesis-work are described in more detail in chapter 3.
The application of the MFM method to the analysis of ferromagnetic materials is
described in chapter 4. A point of interest in the research of these materials is the
influence of the interfaces between ferromagnetic and other materials on the magnetic
properties of the sample. Here, this influence was studied using Cu/Ni/Cu/Si(001)
sandwich structures, because they show a particularly interesting dependence of the
preferred orientation of the magnetization on the thickness of the nickel layer.
Finally, the application of the MFM method to the study of superconductors is
described in chapter 5. In addition to the imaging of the magnetic structures occurring
in the superconductor, the use of the MFM to study the response of the superconductor
to a local applied field is discussed
Rethinking the Bangladesh state
The study of the Bangladesh state continues to be a path less travelled for scholars of South Asia. The articles in this special issue aim to offer fresh perspectives based on recent ethnographic work on a variety of aspects of the state by new young national and international scholars. Overall, there is a pressing need to pay closer attention to the state and to think about it in new ways, and in this brief concluding article, we offer some thoughts on where we are and some pointers towards where we may need to go. While there are many strengths to the small quantity of literature that exists on this theme, there are also some important limitations
Labour Migration and Human Trafficking: An Introduction
Anti-trafficking initiatives grew exponentially since the United Nations passed the UN Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children (hereafter the UN Trafficking Protocol) in 2000. This book contributes to the growing critique of the anti-trafficking agenda by exploring the ways in which the UN Trafficking Protocol has been taken up by policy-makers, non-governmental organizations, and international agencies in Southeast Asia. This region is recognized internationally as a ‘hotspot’ for human trafficking, but there have been few attempts to critically evaluate the vast numbers of anti-trafficking programs and projects or counter-trafficking laws and regulations in operation in the region. Instead, much of the literature has focused on documenting the role that international agencies and NGOs have played in counter-trafficking programs; the development of anti-trafficking laws and policies; or empirical studies of human trafficking cases and/or trends.2 In order to address this gap, the authors in this collection focus their attention at the local level and pay careful, systematic attention to the ways that anti-trafficking initiatives have been taken up and translated by different stakeholders at different scales. As these cases show, anti-trafficking initiatives include rescue and repatriation programs for ‘victims’; education programs about the dangerous habits of smugglers and traffickers; development programs aimed at improving economic livelihoods in ‘hotspots’; and international and bilateral policing efforts aimed at securing borders and arresting people smugglers and traffickers. Associated with the rise of a strong discourse of transnational crime prevention, these initiatives have been accompanied by numerous anti-trafficking laws and protocols passed at local, national and regional levels
- …