843 research outputs found
Influence of Micro-Cantilever Geometry and Gap on Pull-in Voltage
In this paper, we study the behaviour of a microcantilever beam under
electrostatic actuation using finite difference method. This problem has a lot
of applications in MEMS based devices like accelerometers, switches and others.
In this paper, we formulated the problem of a cantilever beam with proof mass
at its end and carried out the finite difference solution. we studied the
effects of length, width, and the gap size on the pull-in voltage using data
that are available in the literature. Also, the stability limit is compared
with the single degree of freedom commonly used in the earlier literature as an
approximation to calculate the pull-in voltage.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Existence of the Bogoliubov S(g) operator for the quantum field theory
We prove the existence of the Bogoliubov S(g) operator for the
quantum field theory for coupling functions of compact support in space and
time. The construction is nonperturbative and relies on a theorem of
Kisy\'nski. It implies almost automatically the properties of unitarity and
causality for disjoint supports in the time variable.Comment: LaTeX, 24 pages, minor modifications, typos correcte
Renormalized energy concentration in random matrices
We define a "renormalized energy" as an explicit functional on arbitrary
point configurations of constant average density in the plane and on the real
line. The definition is inspired by ideas of [SS1,SS3]. Roughly speaking, it is
obtained by subtracting two leading terms from the Coulomb potential on a
growing number of charges. The functional is expected to be a good measure of
disorder of a configuration of points. We give certain formulas for its
expectation for general stationary random point processes. For the random
matrix -sine processes on the real line (beta=1,2,4), and Ginibre point
process and zeros of Gaussian analytic functions process in the plane, we
compute the expectation explicitly. Moreover, we prove that for these processes
the variance of the renormalized energy vanishes, which shows concentration
near the expected value. We also prove that the beta=2 sine process minimizes
the renormalized energy in the class of determinantal point processes with
translation invariant correlation kernels.Comment: last version, to appear in Communications in Mathematical Physic
The Escape Problem in a Classical Field Theory With Two Coupled Fields
We introduce and analyze a system of two coupled partial differential
equations with external noise. The equations are constructed to model
transitions of monovalent metallic nanowires with non-axisymmetric intermediate
or end states, but also have more general applicability. They provide a rare
example of a system for which an exact solution of nonuniform stationary states
can be found. We find a transition in activation behavior as the interval
length on which the fields are defined is varied. We discuss several
applications to physical problems.Comment: 24 page
Resonant Inelastic X-Ray Scattering from Valence Excitations in Insulating Copper-Oxides
We report resonant inelastic x-ray measurements of insulating LaCuO
and SrCuOCl taken with the incident energy tuned near the Cu K
absorption edge. We show that the spectra are well described in a shakeup
picture in 3rd order perturbation theory which exhibits both incoming and
outgoing resonances, and demonstrate how to extract a spectral function from
the raw data. We conclude by showing {\bf q}-dependent measurements of the
charge transfer gap.Comment: minor notational changes, discussion of anderson impurity model
fixed, references added; accepted by PR
Universality of the Wigner time delay distribution for one-dimensional random potentials
We show that the distribution of the time delay for one-dimensional random
potentials is universal in the high energy or weak disorder limit. Our
analytical results are in excellent agreement with extensive numerical
simulations carried out on samples whose sizes are large compared to the
localisation length (localised regime). The case of small samples is also
discussed (ballistic regime). We provide a physical argument which explains in
a quantitative way the origin of the exponential divergence of the moments. The
occurence of a log-normal tail for finite size systems is analysed. Finally, we
present exact results in the low energy limit which clearly show a departure
from the universal behaviour.Comment: 4 pages, 3 PostScript figure
Femtosecond Nuclear Motion of HCl Probed by Resonant X-ray Raman Scattering in the Cl 1s Region
Femtosecond dynamics are observed by resonant x-ray Raman scattering (RXS) after excitation along the dissociative Cl 1sâ6ÆĄ* resonance of gas-phase HCl. The short core-hole lifetime results in a complete breakdown of the common nondispersive behavior of soft-x-ray transitions between parallel potentials. We evidence a general phenomenon of RXS in the hard-x-ray region: a complete quenching of vibrational broadening. This opens up a unique opportunity for superhigh resolution x-ray spectroscopy beyond vibrational and lifetime limitations
Thomson-resonant Interference Effects in Elastic X-ray Scattering Near the Cl K Edge of HCl
We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl K edge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions
On the distribution of the Wigner time delay in one-dimensional disordered systems
We consider the scattering by a one-dimensional random potential and derive
the probability distribution of the corresponding Wigner time delay. It is
shown that the limiting distribution is the same for two different models and
coincides with the one predicted by random matrix theory. It is also shown that
the corresponding stochastic process is given by an exponential functional of
the potential.Comment: 11 pages, four references adde
Protocol: the effects of flipped classrooms to improve learning outcomes in undergraduate health professional education: a systematic review
[Extract] The teaching and learning activities of any undergraduate curriculum will have a specific set of learning outcomes that should be successfully achieved by the students. The balance between the workload of a student and the available time to achieve the learning outcomes plays a major role in achieving these learning outcomes, as well as a good student satisfaction score and excellent final grades for that particular module (Whillier & Lystad, 2013). In a traditional educational experience, a teacher stands in front of the classroom, delivers a lecture to a group of students, who sit in rows, quietly listening to the lecture and taking notes. At the end of the lecture, students are given homework or an assignment to be completed outside of the classroom environment. This characterises the principle of âsageâonâthe stageâ, and is synonymous with the present day term of teacherâcentered learning. This is also referred to as the transmittal model (King, 1993), which assumes that the students are passive noteâtakers, receivers of the content or accumulators of factoids (Morrison, 2014). Usually, the teacher does not have time to interact with the students individually during the class (Hamdan, McKnight, McKnight & Arfstorm, 2013), thus neglecting those students who do not understand the lecture. The traditional didactic way of teaching is primarily unidirectional and consists of limited interactions between the source of knowledge (teacher) and the passive recipients (students)
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