2,085 research outputs found
Normal forms and entanglement measures for multipartite quantum states
A general mathematical framework is presented to describe local equivalence
classes of multipartite quantum states under the action of local unitary and
local filtering operations. This yields multipartite generalizations of the
singular value decomposition. The analysis naturally leads to the introduction
of entanglement measures quantifying the multipartite entanglement (as
generalizations of the concurrence and the 3-tangle), and the optimal local
filtering operations maximizing these entanglement monotones are obtained.
Moreover a natural extension of the definition of GHZ-states to e.g. systems is obtained.Comment: Proof of uniqueness of normal form adde
Identification method based on Zadeh filter models
Mathematical modeling which provides the description of objects and proper organization of control operations in future is an integral stage in the automation of production. One of the approaches to build a mathematical model of an object is to represent nonlinear systems as combinations of inertial and nonlinear inertialess elements. The models thus obtained are called block-oriented. In this paper, we consider nonlinear dynamic objects represented as the models of the Zadeh filter class. In the process of the method development the identification equations were derived for the case when the test signal is a single sinusoid. Then the case of two sinusoids was considered. Such investigations allowed us to identify the patterns and describe the general case for several test components in the signal. The results of digital modeling using the sum of harmonic signals confirm the feasibility and validity of the proposed approach for identifying nonlinear models of the Zadeh filter class
Josephson-like spin current in junctions composed of antiferromagnets and ferromagnets
We study Josephson-like junctions formed by materials with antiferromagnetic
(AF) order parameters. As an antiferromagnet, we consider a two-band material
in which a spin density wave (SDW) arises. This could be Fe-based pnictides in
the temperature interval , where and
are the critical temperatures for the superconducting and
antiferromagnetic transitions, respectively. The spin current
in AF/F/AF junctions with a ballistic ferromagnetic layer and in tunnel AF/I/AF
junctions is calculated. It depends on the angle between the magnetization
vectors in the AF leads in the same way as the Josephson current depends on the
phase difference of the superconducting order parameters in S/I/S tunnel
junctions. It turns out that in AF/F/AF junctions, two components of the SDW
order parameter are induced in the F\nobreakdash-layer. One of them oscillates
in space with a short period
while the other decays monotonously from the interfaces over a long distance of
the order (where , and
are the Fermi velocity, the exchange energy and the temperature, respectively;
the subindex denotes the ballistic case). This is a clear analogy
with the case of Josephson S/F/S junctions with a nonhomogeneous magnetization
where short- and long\nobreakdash-range condensate components are induced in
the F\nobreakdash-layer. However, in contrast to the charge Josephson current
in S/F/S junctions, the spin current in AF/F/AF junctions is not constant in
space, but oscillates in the ballistic F\nobreakdash-layer. We also calculate
the dependence of on the deviation from the ideal nesting in
the AF/I/AF junctions.Comment: 10 pages, 8 figures; Typos corrected; Journal reference adde
Prediction of recovery from multiple organ dysfunction syndrome in pediatric sepsis patients.
MOTIVATION
Sepsis is a leading cause of death and disability in children globally, accounting for ∼3 million childhood deaths per year. In pediatric sepsis patients, the multiple organ dysfunction syndrome (MODS) is considered a significant risk factor for adverse clinical outcomes characterized by high mortality and morbidity in the pediatric intensive care unit. The recent rapidly growing availability of electronic health records (EHRs) has allowed researchers to vastly develop data-driven approaches like machine learning in healthcare and achieved great successes. However, effective machine learning models which could make the accurate early prediction of the recovery in pediatric sepsis patients from MODS to a mild state and thus assist the clinicians in the decision-making process is still lacking.
RESULTS
This study develops a machine learning-based approach to predict the recovery from MODS to zero or single organ dysfunction by 1 week in advance in the Swiss Pediatric Sepsis Study cohort of children with blood-culture confirmed bacteremia. Our model achieves internal validation performance on the SPSS cohort with an area under the receiver operating characteristic (AUROC) of 79.1% and area under the precision-recall curve (AUPRC) of 73.6%, and it was also externally validated on another pediatric sepsis patients cohort collected in the USA, yielding an AUROC of 76.4% and AUPRC of 72.4%. These results indicate that our model has the potential to be included into the EHRs system and contribute to patient assessment and triage in pediatric sepsis patient care.
AVAILABILITY AND IMPLEMENTATION
Code available at https://github.com/BorgwardtLab/MODS-recovery. The data underlying this article is not publicly available for the privacy of individuals that participated in the study.
SUPPLEMENTARY INFORMATION
Supplementary data are available at Bioinformatics online
The Electromagnetic Lorentz Condition Problem and Symplectic Properties of Maxwell and Yang-Mills Type Dynamical Systems
Symplectic structures associated to connection forms on certain types of
principal fiber bundles are constructed via analysis of reduced geometric
structures on fibered manifolds invariant under naturally related symmetry
groups. This approach is then applied to nonstandard Hamiltonian analysis of of
dynamical systems of Maxwell and Yang-Mills type. A symplectic reduction theory
of the classical Maxwell equations is formulated so as to naturally include the
Lorentz condition (ensuring the existence of electromagnetic waves), thereby
solving the well known Dirac -Fock - Podolsky problem. Symplectically reduced
Poissonian structures and the related classical minimal interaction principle
for the Yang-Mills equations are also considered. 1
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