2,469 research outputs found
Transition of amorphous to crystalline oxide film in initial oxide overgrowth on liquid metals
It is important to understand the mechanism of oxidation in the initial stage on the free surface of liquid metals. Mittemeijer and co-workers recently developed a thermodynamic model to study the oxide overgrowth on a solid metal surface. Based on this model, we have developed a thermodynamic model to analyse the thermodynamic stability of oxide overgrowth on liquid metals. The thermodynamic model calculation revealed that the amorphous oxide phase is thermodynamically preferred up to 1.3 and 0.35 nm respectively, in the initial oxide overgrowth on liquid Al and Ga at the corresponding melting point. However, the amorphous phase is thermodynamically unstable in the initial oxide overgrowth on liquid Mg. The thermodynamic stability of amorphous phase in the Al and Ga oxide systems is attributed to lower sums of surface and interfacial energies for amorphous phases, compared to that of the corresponding crystalline phases.Financial support under grant EP/H026177/1 from the EPSRC was used
Digital Accessibility in Iran: An Investigation Focusing on Iran\u27s National Policies on Accessibility and Disability Support
Digital accessibility has become an important topic in the field of HCI, but when looking at accessibility on a global scale, we find that the representation of accessibility research is mostly centered in the Global North with countries that are WEIRD (Western, Educated, Industrialized, Rich, and Democratic). Our paper explores digital accessibility in Iran, focusing exclusively on its national policies on accessibility. Iran is a non-WEIRD country located in the Global South, with no reports on its digital accessibility status from the Global Initiative for Inclusive Information and Communication Technologies (G3ict). We found that there is not enough focus on accessibility in Iran\u27s regulations and we conclude our paper by recommending directions for improving this situation such as HCI and disability organizations in Iran cooperating with G3ict
Exploring Accessibility Features and Plug-ins for Digital Prototyping Tools
Many digital systems are found to be inaccessible and a large part of the issue is that accessibility is not considered early enough in the design process. Digital prototyping tools are a powerful resource for designers to quickly explore both low and high fidelity design mockups during initial stages of product design and development. We evaluated 10 popular prototyping tools to understand their built-in and third-party accessibility features. We found that accessible design support is largely from third-party plug-ins rather than prototyping tools\u27 built-in features, and the availability of accessibility support varies from tool to tool. There is potential to improve accessible design by increasing the potential for accessibility to be consider earlier in the design process
Website Builders Still Contribute To Inaccessible Web Design
Website builders enable individuals without design or technical skills to create websites. However, it is unclear if modern websites created by website builders meet accessibility standards. We reviewed six popular website building platforms and found a lack of accessibility support. Wix provided the most comprehensive accessibility documentation and robust accessibility features. However, during an accessibility audit of 90 Wix webpages, we found many accessibility issues, raising concerns about how users are supported
Global Optical Control of a Quantum Spin Chain
Quantum processors which combine the long decoherence times of spin qubits
together with fast optical manipulation of excitons have recently been the
subject of several proposals. I show here that arbitrary single- and entangling
two-qubit gates can be performed in a chain of perpetually coupled spin qubits
solely by using laser pulses to excite higher lying states. It is also
demonstrated that universal quantum computing is possible even if these pulses
are applied {\it globally} to a chain; by employing a repeating pattern of four
distinct qubit units the need for individual qubit addressing is removed. Some
current experimental qubit systems would lend themselves to implementing this
idea.Comment: 5 pages, 3 figure
Phase transitions of a tethered surface model with a deficit angle term
Nambu-Goto model is investigated by using the canonical Monte Carlo
simulations on fixed connectivity surfaces of spherical topology. Three
distinct phases are found: crumpled, tubular, and smooth. The crumpled and the
tubular phases are smoothly connected, and the tubular and the smooth phases
are connected by a discontinuous transition. The surface in the tubular phase
forms an oblong and one-dimensional object similar to a one-dimensional linear
subspace in the Euclidean three-dimensional space R^3. This indicates that the
rotational symmetry inherent in the model is spontaneously broken in the
tubular phase, and it is restored in the smooth and the crumpled phases.Comment: 6 pages with 6 figure
Particle Acceleration and Magnetic Dissipation in Relativistic Current Sheet of Pair Plasmas
We study linear and nonlinear development of relativistic and
ultrarelativistic current sheets of pair plasmas with antiparallel magnetic
fields. Two types of two-dimensional problems are investigated by
particle-in-cell simulations. First, we present the development of relativistic
magnetic reconnection, whose outflow speed is an order of the light speed c. It
is demonstrated that particles are strongly accelerated in and around the
reconnection region, and that most of magnetic energy is converted into
"nonthermal" part of plasma kinetic energy. Second, we present another
two-dimensional problem of a current sheet in a cross-field plane. In this
case, the relativistic drift kink instability (RDKI) occurs. Particle
acceleration also takes place, but the RDKI fast dissipates the magnetic energy
into plasma heat. We discuss the mechanism of particle acceleration and the
theory of the RDKI in detail. It is important that properties of these two
processes are similar in the relativistic regime of T > mc^2, as long as we
consider the kinetics. Comparison of the two processes indicates that magnetic
dissipation by the RDKI is more favorable process in the relativistic current
sheet. Therefore the striped pulsar wind scenario should be reconsidered by the
RDKI.Comment: To appear in ApJ vol. 670; 60 pages, 27 figures; References and typos
are fixe
Controlling for Confounders in Multimodal Emotion Classification via Adversarial Learning
Various psychological factors affect how individuals express emotions. Yet,
when we collect data intended for use in building emotion recognition systems,
we often try to do so by creating paradigms that are designed just with a focus
on eliciting emotional behavior. Algorithms trained with these types of data
are unlikely to function outside of controlled environments because our
emotions naturally change as a function of these other factors. In this work,
we study how the multimodal expressions of emotion change when an individual is
under varying levels of stress. We hypothesize that stress produces modulations
that can hide the true underlying emotions of individuals and that we can make
emotion recognition algorithms more generalizable by controlling for variations
in stress. To this end, we use adversarial networks to decorrelate stress
modulations from emotion representations. We study how stress alters acoustic
and lexical emotional predictions, paying special attention to how modulations
due to stress affect the transferability of learned emotion recognition models
across domains. Our results show that stress is indeed encoded in trained
emotion classifiers and that this encoding varies across levels of emotions and
across the lexical and acoustic modalities. Our results also show that emotion
recognition models that control for stress during training have better
generalizability when applied to new domains, compared to models that do not
control for stress during training. We conclude that is is necessary to
consider the effect of extraneous psychological factors when building and
testing emotion recognition models.Comment: 10 pages, ICMI 201
Electron spin coherence in metallofullerenes: Y, Sc and La@C82
Endohedral fullerenes encapsulating a spin-active atom or ion within a carbon
cage offer a route to self-assembled arrays such as spin chains. In the case of
metallofullerenes the charge transfer between the atom and the fullerene cage
has been thought to limit the electron spin phase coherence time (T2) to the
order of a few microseconds. We study electron spin relaxation in several
species of metallofullerene as a function of temperature and solvent
environment, yielding a maximum T2 in deuterated o-terphenyl greater than 200
microseconds for Y, Sc and La@C82. The mechanisms governing relaxation (T1, T2)
arise from metal-cage vibrational modes, spin-orbit coupling and the nuclear
spin environment. The T2 times are over 2 orders of magnitude longer than
previously reported and consequently make metallofullerenes of interest in
areas such as spin-labelling, spintronics and quantum computing.Comment: 5 pages, 4 figure
Liesegang patterns: Effect of dissociation of the invading electrolyte
The effect of dissociation of the invading electrolyte on the formation of
Liesegang bands is investigated. We find, using organic compounds with known
dissociation constants, that the spacing coefficient, 1+p, that characterizes
the position of the n-th band as x_n ~ (1+p)^n, decreases with increasing
dissociation constant, K_d. Theoretical arguments are developed to explain
these experimental findings and to calculate explicitly the K_d dependence of
1+p.Comment: RevTex, 8 pages, 3 eps figure
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