2,127 research outputs found
Canonical circuit quantization with linear nonreciprocal devices
Nonreciprocal devices effectively mimic the breaking of time-reversal
symmetry for the subspace of dynamical variables that they couple, and can be
used to create chiral information processing networks. We study the systematic
inclusion of ideal gyrators and circulators into Lagrangian and Hamiltonian
descriptions of lumped-element electrical networks. The proposed theory is of
wide applicability in general nonreciprocal networks on the quantum regime. We
apply it to pedagogical and pathological examples of circuits containing
Josephson junctions and ideal nonreciprocal elements described by admittance
matrices, and compare it with the more involved treatment of circuits based on
nonreciprocal devices characterized by impedance or scattering matrices.
Finally, we discuss the dual quantization of circuits containing phase-slip
junctions and nonreciprocal devices.Comment: 12 pages, 4 figures; changes made to match the accepted version in
PR
Geometrical description and Faddeev-Jackiw quantization of electrical networks
In lumped-element electrical circuit theory, the problem of solving Maxwell's
equations in the presence of media is reduced to two sets of equations. Those
addressing the local dynamics of a confined energy density, the constitutive
equations, encapsulating local geometry and dynamics, and those that enforce
the conservation of charge and energy in a larger scale that we express
topologically, the Kirchhoff equations. Following a consistent geometrical
description, we develop a new and systematic way to write the dynamics of
general lumped-element electrical circuits as first order differential
equations derivable from a Lagrangian and a Rayleigh dissipation function.
Leveraging the Faddeev-Jackiw method, we identify and classify all
singularities that arise in the search for Hamiltonian descriptions of general
networks. Furthermore we provide systematics to solve those singularities,
which is a key problem in the context of canonical quantization of
superconducting circuits. The core of our solution relies on the correct
identification of the reduced manifold in which the circuit state is
expressible, e.g., a mix of flux and charge degrees of freedom, including the
presence of compact ones. We apply the fully programmable method to obtain
(canonically quantizable) Hamiltonian descriptions of nonlinear and
nonreciprocal circuits which would be cumbersome/singular if pure node-flux or
loop-charge variables are used as a starting configuration space. This work
unifies diverse existent geometrical pictures of electrical network theory, and
will prove useful, for instance, to automatize the computation of exact
Hamiltonian descriptions of superconducting quantum chips.Comment: 19 pages and 10 figures. Comments are welcom
On the sensitivity reach of LQ production with preferential couplings to third generation fermions at the LHC
Leptoquarks (LQs) are hypothetical particles that appear in various
extensions of the Standard Model (SM) that can explain observed differences
between SM theory predictions and experimental results. The production of these
particles has been widely studied at various experiments, most recently at the
Large Hadron Collider (LHC), and stringent bounds have been placed on their
masses and couplings, assuming the simplest beyond-SM (BSM) hypotheses.
However, the limits are significantly weaker for LQ models with family
non-universal couplings containing enhanced couplings to third-generation
fermions. We present a new study on the production of a LQ at the LHC, with
preferential couplings to third-generation fermions, considering proton-proton
collisions at and
. Such a hypothesis is well motivated theoretically and it can
explain the recent anomalies in the precision measurements of
-meson decay rates, specifically the ratios. Under a
simplified model where the LQ masses and couplings are free parameters, we
focus on cases where the LQ decays to a lepton and a quark,
and study how the results are affected by different assumptions about chiral
currents and interference effects with other BSM processes with the same final
states, such as diagrams with a heavy vector boson, . The
analysis is performed using machine learning techniques, resulting in an
increased discovery reach at the LHC and allowing us to probe the entirety of
the new physics phase space which addresses the -meson anomalies,
for LQ masses up to 2.25 .Comment: 26 pages, 13 figure
Graph-Based Permutation Patterns for the Analysis of Task-Related fMRI Signals on DTI Networks in Mild Cognitive Impairment
Permutation Entropy () is a powerful nonlinear analysis technique for
univariate time series. Very recently, Permutation Entropy for Graph signals
() has been proposed to extend to data residing on irregular
domains. However, is limited as it provides a single value to
characterise a whole graph signal. Here, we introduce a novel approach to
evaluate graph signals at the vertex level: graph-based permutation patterns.
Synthetic datasets show the efficacy of our method. We reveal that dynamics in
graph signals, undetectable with , can be discerned using our graph-based
permutation patterns. These are then validated in the analysis of DTI and fMRI
data acquired during a working memory task in mild cognitive impairment, where
we explore functional brain signals on structural white matter networks. Our
findings suggest that graph-based permutation patterns change in individual
brain regions as the disease progresses. Thus, graph-based permutation patterns
offer promise by enabling the granular scale analysis of graph signals.Comment: 5 pages, 5 figures, 1 tabl
A Measurement Study of Online Tracking and Advertising in Ibero-America
The ability of the online marketing industry to track and profile users’ Web-browsing activity is what enables effective, tailored-made advertising services. The intrusiveness of these practices and the increasing invasiveness of digital advertising, however, have raised serious concerns regarding user privacy. Although the level of ubiquity of tracking and advertising has been investigated in top-world sites based in North America and Western Europe, the extent to which those practices are carried out in territories with less or no legal coverage —in terms of data protection— has not been studied so far. In this work, we present the first detailed measurement of online tracking and advertising conducted to date in one of those regions, namely, Ibero-America, by analyzing local websites (e.g., education and government sites). In doing so, our measurement study aims to find out how user location as well as the type of publisher may impact on tracking and advertising and thus user privacy. Lastly, our thorough, extensive analysis also explores whether differences are appreciated between Latin America and the EU with regard to the third-party tracking conducted from and towards the corresponding countries
Promising developments in neuropsychological approaches for the detection of preclinical Alzheimer’s disease: a selective review
Recently published guidelines suggest that the most opportune time to treat individuals with Alzheimer’s disease is during the preclinical phase of the disease. This is a phase when individuals are defined as clinically normal but exhibit evidence of amyloidosis, neurodegeneration and subtle cognitive/behavioral decline. While our standard cognitive tests are useful for detecting cognitive decline at the stage of mild cognitive impairment, they were not designed for detecting the subtle cognitive variations associated with this biomarker stage of preclinical Alzheimer’s disease. However, neuropsychologists are attempting to meet this challenge by designing newer cognitive measures and questionnaires derived from translational efforts in neuroimaging, cognitive neuroscience and clinical/experimental neuropsychology. This review is a selective summary of several novel, potentially promising, approaches that are being explored for detecting early cognitive evidence of preclinical Alzheimer’s disease in presymptomatic individuals
Prevalence and risk factors for asthma, rhinitis, eczema, and atopy among preschool children in an Andean city.
BACKGROUND: Limited data are available on prevalence and associated risk factors for atopy and allergic diseases from high-altitude urban settings in Latin America. OBJECTIVE: To estimate the prevalence of atopy, asthma, rhinitis, and eczema, and associations with relevant risk factors in preschool children in the Andean city of Cuenca. METHODS: A cross-sectional study was undertaken using a representative sample of 535 children aged 3-5 years attending 30 nursery schools in the city of Cuenca, Ecuador. Data on allergic diseases and risk factors were collected by parental questionnaire. Atopy was measured by skin prick test (SPT) reactivity to a panel of relevant aeroallergens. Associations between risk factors and the prevalence of atopy and allergic diseases were estimated using multivariable logistic regression. RESULTS: Asthma symptoms were reported for 18% of children, rhinitis for 48%, and eczema for 28%, while SPT reactivity was present in 33%. Population fractions of asthma, rhinitis, and eczema attributable to SPT were 3.4%, 7.9%, and 2.9%, respectively. In multivariable models, an increased risk of asthma was observed among children with a maternal history of rhinitis (OR 1.85); rhinitis was significantly increased in children of high compared to low socioeconomic level (OR 2.09), among children with a maternal history of rhinitis (OR 2.29) or paternal history of eczema (OR 2.07), but reduced among children attending daycare (OR 0.64); eczema was associated with a paternal history of eczema (OR 3.73), and SPT was associated with having a dog inside the house (OR 1.67). CONCLUSIONS: A high prevalence of asthma, rhinitis, and eczema symptoms were observed among preschool children in a high-altitude Andean setting. Despite a high prevalence of atopy, only a small fraction of symptoms was associated with atopy. Parental history of allergic diseases was the most consistent risk factor for symptoms in preschool children
Optimization of an Exploratory Oncology Panel for Immunoprofiling Tissues in the Tumor Microenvironment using CO-Detection by indEXing (CODEX) Methodology
https://openworks.mdanderson.org/sumexp21/1205/thumbnail.jp
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