13,230 research outputs found
Microcircuit testing and fabrication, using scanning electron microscopes
Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances
Gamow-Teller properties of the double beta-decay partners 116Cd(Sn) and 150Nd(Sm)
The two Gamow-Teller (GT) branches connecting the double-beta decay partners
(116Cd, 116Sn) and (150Nd, 150Sm) with the intermediate nuclei 116In and 150Pm
are studied within a microscopic approach based on a deformed proton-neutron
quasiparticle random-phase approximation built on a Skyrme selfconsistent mean
field with pairing correlations and spin-isospin residual forces. The results
are compared with the experimental GT strength distributions extracted from
charge-exchange reactions. Combining the two branches, the nuclear matrix
elements for the two-neutrino double-beta decay are evaluated and compared to
experimental values derived from the measured half-lives.Comment: 10 pages, 16 figure
Regulating Mobile Mental Health Apps
Mobile medical apps (MMAs) are a fast‐growing category of software typically installed on personal smartphones and wearable devices. A subset of MMAs are aimed at helping consumers identify mental states and/or mental illnesses. Although this is a fledgling domain, there are already enough extant mental health MMAs both to suggest a typology and to detail some of the regulatory issues they pose. As to the former, the current generation of apps includes those that facilitate self‐assessment or self‐help, connect patients with online support groups, connect patients with therapists, or predict mental health issues. Regulatory concerns with these apps include their quality, safety, and data protection. Unfortunately, the regulatory frameworks that apply have failed to provide coherent risk‐assessment models. As a result, prudent providers will need to progress with caution when it comes to recommending apps to patients or relying on app‐generated data to guide treatment
Single-particle dispersion in stably stratified turbulence
We present models for single-particle dispersion in vertical and horizontal
directions of stably stratified flows. The model in the vertical direction is
based on the observed Lagrangian spectrum of the vertical velocity, while the
model in the horizontal direction is a combination of a continuous-time
eddy-constrained random walk process with a contribution to transport from
horizontal winds. Transport at times larger than the Lagrangian turnover time
is not universal and dependent on these winds. The models yield results in good
agreement with direct numerical simulations of stratified turbulence, for which
single-particle dispersion differs from the well studied case of homogeneous
and isotropic turbulence
New Internal Stress Driven on-Chip Micromachines for Extracting Mechanical Properties of Thin Films
A new concept of micromachines has been developed for measuring the
mechanical properties of thin metallic films. The actuator is a beam undergoing
large internal stresses built up during the deposition process. Al thin films
are deposited partly on the actuator beam and on the substrate. By etching the
structure, the actuator contracts and pulls the Al film. Full stress strain
curves can be generated by designing a set of micromachines with various
actuator lengths. In the present study, the displacements have been measured by
scanning electronic microscopy. The stress is derived from simple continuum
mechanics relationships. The tensile properties of Al films of various
thicknesses have been tested. A marked increase of the strength with decreasing
film thickness is observed.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
On connectivity-dependent resource requirements for digital quantum simulation of -level particles
A primary objective of quantum computation is to efficiently simulate quantum
physics. Scientifically and technologically important quantum Hamiltonians
include those with spin-, vibrational, photonic, and other bosonic degrees
of freedom, i.e. problems composed of or approximated by -level particles
(qudits). Recently, several methods for encoding these systems into a set of
qubits have been introduced, where each encoding's efficiency was studied in
terms of qubit and gate counts. Here, we build on previous results by including
effects of hardware connectivity. To study the number of SWAP gates required to
Trotterize commonly used quantum operators, we use both analytical arguments
and automatic tools that optimize the schedule in multiple stages. We study the
unary (or one-hot), Gray, standard binary, and block unary encodings, with
three connectivities: linear array, ladder array, and square grid. Among other
trends, we find that while the ladder array leads to substantial efficiencies
over the linear array, the advantage of the square over the ladder array is
less pronounced. These results are applicable in hardware co-design and in
choosing efficient qudit encodings for a given set of near-term quantum
hardware. Additionally, this work may be relevant to the scheduling of other
quantum algorithms for which matrix exponentiation is a subroutine.Comment: Accepted to QCE20 (IEEE Quantum Week). Corrected erroneous circuits
in Figure
Cram\'er-Rao bounds for synchronization of rotations
Synchronization of rotations is the problem of estimating a set of rotations
R_i in SO(n), i = 1, ..., N, based on noisy measurements of relative rotations
R_i R_j^T. This fundamental problem has found many recent applications, most
importantly in structural biology. We provide a framework to study
synchronization as estimation on Riemannian manifolds for arbitrary n under a
large family of noise models. The noise models we address encompass zero-mean
isotropic noise, and we develop tools for Gaussian-like as well as heavy-tail
types of noise in particular. As a main contribution, we derive the
Cram\'er-Rao bounds of synchronization, that is, lower-bounds on the variance
of unbiased estimators. We find that these bounds are structured by the
pseudoinverse of the measurement graph Laplacian, where edge weights are
proportional to measurement quality. We leverage this to provide interpretation
in terms of random walks and visualization tools for these bounds in both the
anchored and anchor-free scenarios. Similar bounds previously established were
limited to rotations in the plane and Gaussian-like noise
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