665 research outputs found
New insights into electron spin dynamics in the presence of correlated noise
The changes of the spin depolarization length in zinc-blende semiconductors
when an external component of correlated noise is added to a static driving
electric field are analyzed for different values of field strength, noise
amplitude and correlation time. Electron dynamics is simulated by a Monte Carlo
procedure which keeps into account all the possible scattering phenomena of the
hot electrons in the medium and includes the evolution of spin polarization.
Spin depolarization is studied by examinating the decay of the initial spin
polarization of the conduction electrons through the D'yakonov-Perel process,
the only relevant relaxation mechanism in III-V crystals. Our results show
that, for electric field amplitude lower than the Gunn field, the dephasing
length shortens with the increasing of the noise intensity. Moreover, a
nonmonotonic behavior of spin depolarization length with the noise correlation
time is found, characterized by a maximum variation for values of noise
correlation time comparable with the dephasing time. Instead, in high field
conditions, we find that, critically depending on the noise correlation time,
external fluctuations can positively affect the relaxation length. The
influence of the inclusion of the electron-electron scattering mechanism is
also shown and discussed.Comment: Published on "Journal of Physics: Condensed Matter" as "Fast Track
Communications", 11 pages, 9 figure
On Rationality
Rationality is an enduring topic of interest across the disciplines and has become even more so, given the current crises that are unfolding in our society. The four books reviewed here, which are written by academics working in economics, political science, political theory and philosophy, provide an interdisciplinary engagement with the idea of rationality and the way it has shaped the institutional frameworks and global political economy of our time. Rational choice theory has certainly proved to be a useful analytic tool in certain contexts, and instrumental reason has been a key tenet of human progress in several periods of history, including the industrial revolution and the modernity that emerged in the nineteenth century. Given the complexity of our current challenges, however, is it time to ask whether this paradigm might be better complemented by more holistic and heterodox approaches? Hindmoor A and Taylor TY (2015) Rational Choice (Political Analysis), 2nd edn. London; New York: Palgrave Macmillan. Massumi (2015) The Power at the End of the Economy. Durham: Duke University Press. Brown (2015) Undoing the Demos: Neoliberalismâs Stealth Revolution. New York: Zone Books. Ludovisi SG (ed.) (2015) Critical Theory and the Challenge of Praxis: Beyond Reification. Farnham; Burlington, VT: Ashgate
Relaxation of Electron Spin during High-Field Transport in GaAs Bulk
A semiclassical Monte Carlo approach is adopted to study the multivalley spin
depolarization of drifting electrons in a doped n-type GaAs bulk semiconductor,
in a wide range of lattice temperature ( K) and doping density
(cm). The decay of the initial non-equilibrium spin
polarization of the conduction electrons is investigated as a function of the
amplitude of the driving static electric field, ranging between 0.1 and 6
kV/cm, by considering the spin dynamics of electrons in both the and
the upper valleys of the semiconductor. Doping density considerably affects
spin relaxation at low temperature and weak intensity of the driving electric
field. At high values of the electric field, the strong spin-orbit coupling of
electrons in the -valleys significantly reduces the average spin
polarization lifetime, but, unexpectedly, for field amplitudes greater than 2.5
kV/cm, the spin lifetime increases with the lattice temperature. Our numerical
findings are validated by a good agreement with the available experimental
results and with calculations recently obtained by a different theoretical
approach.Comment: 14 pages, 6 figure
Hybrid kinematic control for rigid body pose stabilization using dual quaternions
In this paper, we address the rigid body pose stabilization problem using dual quaternion formalism. We propose a hybrid control strategy to design a switching control law with hysteresis in such a way that the global asymptotic stability of the closed-loop system is guaranteed and such that the global attractivity of the stabilization pose does not exhibit chattering, a problem that is present in all discontinuous-based feedback controllers. Using numerical simulations, we illustrate the problems that arise from existing results in the literatureâas unwinding and chatteringâand verify the effectiveness of the proposed controller to solve the robust global pose stability problem
An innovative tailored instructional design for computer programming courses in engineering
Industry 4.0 and 5.0 topics are emerging fields and have seen rising demand recently. There is a critical need, on the other hand, for improved methods of instructing programming languages since a growing lack of student motivation during the pandemic has had a deleterious influence on the education of programmers. In this context, online/hybrid computer programming courses must be addressed with innovative solutions to support the field with well-educated professionals. In this paper, we present a case study to propose an innovative tailored instructional design for the online/hybrid learning environments for programming courses in engineering faculties. To develop the instructional design, the Kemp Instructional Design Model was followed. The instructional design is a result of the main outputs of the RECOM âRedesigning Introductory Computer Programming Using Innovative Online Modulesâ project, which aims to bridge the gap between the existing course design in programming courses and the needs of "Covidâ and âpost-Covidâ generation students
Young Women and Consumer Culture
This article is presented as an intervention in the field of feminist media and cultural studies with particular reference to consumer culture. It is concerned with the seeming evasion of critique which can be detected in a number of recent feminist responses to the way in which modalities of âpopular feminismâ have found themselves incorporated into women's genres of television, such as, in particular, the US series Sex in the City. This usage or instrumentalization of feminism (in its most conventionally liberal feminist guise) also provides corporate culture with the means of presenting itself to young women as their ally and even champion of âgirlsâ while at the same time earning seeming approval for adopting the mantle of social responsibility, which makes the concept of popular feminism more problematic than it first appeared. Such appropriation of popular feminist discourse by the commercial domain prompts a self-critique on the part of the author alongside an analysis of recent approaches toward consumer culture in cultural studies. The article continues by presenting a schematic account of how the commercial domain increasingly supplants state and public sector institutions in the intensity and dedication of its address to girls and young women. Whilst some may argue that the intersection of youthful femininity and the commercial sphere is not a new phenomenon, what is being explored here is the connection between this intensification of attention and the logic of current neo-liberal economic rationalities. The argument is, therefore, that it is by these means including the instrumentalization of a specific modality of âfeminismâ that there emerges into existence a neo-liberal culture, with global aspirations, which has as its ideal subject the category of âgirlâ
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