Results 31 to 40 of about 18,081 (306)

On the Completely Positive and Positive Semidefinite-Preserving Cones—Part III [PDF]

ISRN Algebra, 2012
This paper studies the extremals and other faces of the completely positive and positive semidefinite-preserving linear transformations.
Andrew J. Klimas, Richard D. Hill
openaire   +2 more sources

\({K}\)-Positivity Preservers and Their Generators

SIAM Journal on Applied Algebra and Geometry
We study $K$-positivity preservers with given closed $K\subseteq\mathbb{R}^n$, i.e., linear maps $T:\mathbb{R}[x_1,\dots,x_n]\to\mathbb{R}[x_1,\dots,x_n]$ such that $T\mathrm{Pos}(K)\subseteq\mathrm{Pos}(K)$ holds, and their generators $A:\mathbb{R}[x_1,\dots,x_n]\to\mathbb{R}[x_1,\dots,x_n]$, i.e., $e^{tA}\mathrm{Pos}(K)\subseteq\mathrm{Pos}(K)$ holds
Philipp Di Dio, Konrad Schmüdgen
openaire   +2 more sources

Total positivity order and the normal distribution

, 2006
International audienceUnlike the usual stochastic order, total positivity order is closed under conditioning. Here we provide a general formulation of the preservation properties of the order under conditioning; we study certain properties of the order ...
Marco Scarsini, Scarsini, Marco, Rinott, Yosef, Yosef Rinott   +3 more
core   +2 more sources

Positivity-preserving strategies and their comparision based on staggered CPR methods

Kongqi donglixue xuebao
High-order accurate algorithms often encounter numerical instabilities, such as negative density or pressure, when simulating flow fields with strong discontinuities, extremely low density, or low pressure.
Weizhe Wang, Zhen-Guo Yan, Huajun Zhu, Xinlong Feng   +3 more
doaj   +1 more source

Stability and Positivity Preservation in Conventional Methods for Space-Fractional Diffusion Problems: Analysis and Algorithms

Algorithms
The numerical solution of space-fractional diffusion problems is investigated focusing on stability and non-negativity issues. The extension of classical schemes is analyzed for the case of the spectral fractional Dirichlet Laplacian operator.
Menghis T. Bahlibi, Ferenc Izsák
doaj   +1 more source

Positivity Preserving non-Markovian Master Equation for Open Quantum System Dynamics: Stochastic Schr\"{o}dinger Equation Approach

, 2023
Positivity preservation is naturally guaranteed in exact non-Markovian master equations for open quantum system dynamics. However, in many approximated non-Markovian master equations, the positivity of the reduced density matrix is not guaranteed.
Chen, Yusui, Wang, Jin, Ding, Quanzhen, Shi, Wufu, Yu, Ting   +4 more
core   +1 more source

On positivity preservation for free quantum fields

, 1975
Let A be a real Bose or Fermi one-particle operator with ∥ A ∥ ⩽ I. Using Kaplansky's density theorem, a simple proof is given of the fact that Γ(A), the operator in Fock space induced by A, is positivity preserving in the relevant L2 ...
Perez, J.Fernando, Wilde, Ivan F
core   +2 more sources

On a positivity preservation property for Schrödinger operators on Riemannian manifolds

, 2015
We study a positivity preservation property for Schrödinger operators with singular potential on geodesically complete Riemannian manifolds with non-negative Ricci curvature.
Milatovic, Ognjen, Ognjen Milatovic
core   +1 more source

Positivity-preserving scheme for two-dimensional advection-diffusion equations including mixed derivatives [PDF]

, 2018
In this work, we propose a positivity-preserving scheme for solving two-dimensional advection-diffusion equations including mixed derivative terms, in order to improve the accuracy of lower-order methods.
Vann, Roderick G L, E.J. du Toit, O'Brien, Martin R., Du Toit, Erasmus J., M.R. O’Brien, R.G.L. Vann   +5 more
core   +1 more source

European Standard Clinical Practice Guideline and EXPeRT Recommendations for the Diagnosis and Management of Gastroenteropancreatic Neuroendocrine Neoplasms in Children and Adolescents

Pediatric Blood &Cancer, EarlyView.
ABSTRACT Pediatric gastroenteropancreatic neuroendocrine neoplasms (GEP‐NENs) are extremely rare and clinically heterogeneous. Management has largely been extrapolated from adult practice. This European Standard Clinical Practice Guideline (ESCP), developed by the EXPeRT network in collaboration with adult NEN experts, provides (adult) evidence ...
Michaela Kuhlen, Calogero Virgone, Antje Redlich, Michael Abele, Ricardo Lopez‐Almaraz, Tal Ben‐Ami, Ewa Bien, Gianni Bisogno, Maja Mazic Cesen, Andrea Ferrari, Malgorzata A. Krawczyk, Yves Reguerre, Dominik T. Schneider, Ines B. Brecht, Charlotte Rigaud, Bilgehan Yalcin, Rainer Claus, Christian Vokuhl, Constantin Lapa, Jörg Fuchs, Segolene Hescot, Thomas Walter, Julien Hadoux, Daniel Orbach   +23 more
wiley   +1 more source