Variational fitting of the Fock exchange potential with modified Cholesky decomposition.

The variational fitting of the Fock potential employing localized molecular orbitals requires either the inversion of the local two-center Coulomb matrices or alternatively the solution of corresponding linear equation systems with these matrices. In both cases, the method of choice is the Cholesky decomposition of the formally positive definite local two-center Coulomb matrices. However, due to finite-precision round-off errors, the local Coulomb matrices may be indefinite, and thus, the Cholesky decomposition is not applicable.

Variational Density Fitting with a Krylov Subspace Method.

In this work, we present the implementation of a variational density fitting methodology that uses iterative linear algebra for solving the associated system of linear equations. It is well known that most difficulties with this system arise from the fact that the coefficient matrix is in general ill-conditioned and, due to finite precision round-off errors, it may not be positive definite. The dimensionality, given by the number of auxiliary functions, also poses a challenge in terms of memory and time demand since the coefficient matrix is dense.

Asymmetric Density Fitting with Modified Cholesky Decomposition Applied to Second-Order Electron Propagator.

Computation of molecular orbital electron repulsion integrals (MO-ERIs) as a transformation from atomic orbital ERIs (AO-ERIs) is the bottleneck of second-order electron propagator calculations when a single orbital is studied. In this contribution, asymmetric density fitting is combined with modified Cholesky decomposition to generate efficiently the required MO-ERIs. The key point of the presented algorithms is to keep track of integrals through partial contractions performed on three-center AO-ERIs; these contractions are stored in RAM instead of the AO-ERIs.

Comparison of the amount and patterns of late enhancement in Chagas disease according to the presence and type of ventricular tachycardia.

Background: Ventricular tachycardia (VT) is one of the main predictors of mortality in Chagas cardiomyopathy (CC). Although the substrate of sustained and nonsustained-VT (NS-VT) seems to be the same, little is known about the distribution of late enhancement (LE). Our aim was to compare the clinical findings and the amount and patterns of LE in Chagas disease according to the presence and type of VT.

Influence of renal dysfunction phenotype on mortality in decompensated heart failure with preserved and mid-range ejection fraction.

Background: Natriuretic peptides or the blood urea nitrogen to creatinine ratio (BUN/creat) can identify high- vs low-risk renal impairment (RI) in patients with heart failure and reduced ejection fraction (HF-REF). However, the situation in HF patients with preserved ejection fraction (HF-PEF) and mid-range ejection fraction (HF-MREF) remains unclear.

Methods: We evaluated patients from the Spanish National Registry of Heart Failure (RICA) that were admitted to Internal Medicine units with acute decompensated HF.

[Discriminant analysis to predict the clinical diagnosis of primary immunodeficiencies: a preliminary report].

Background: The features in a clinical history from a patient with suspected primary immunodeficiency (PID) direct the differential diagnosis through pattern recognition. PIDs are a heterogeneous group of more than 250 congenital diseases with increased susceptibility to infection, inflammation, autoimmunity, allergy and malignancy. Linear discriminant analysis (LDA) is a multivariate supervised classification method to sort objects of study into groups by finding linear combinations of a number of variables.

Emotional response to virtual reality exposure across different cultures: the role of the attribution process.

Many studies have shown the ability of media--television, movies, and virtual reality (VR) experiences--to elicit emotions. Nevertheless, it is still unclear how the different factors involved--user related and medium related--play a role in producing an emotional response during a VR experience. We investigate this issue, analyzing the role played by the cultural and technological backgrounds of the users in the emotional responses to VR.

Robust and efficient density fitting.

In this paper we propose an iterative method for solving the inhomogeneous systems of linear equations associated with density fitting. The proposed method is based on a version of the conjugate gradient method that makes use of automatically built quasi-Newton preconditioners. The paper gives a detailed description of a parallel implementation of the new method.

Characterization of the antiallergic drugs 3-[2-(2-phenylethyl) benzoimidazole-4-yl]-3-hydroxypropanoic acid and ethyl 3-hydroxy-3-[2-(2-phenylethyl)benzoimidazol-4-yl]propanoate as full aryl hydrocarbon receptor agonists.

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates most of the toxic effects of numerous chlorinated (e.g., TCDD) and nonchlorinated polycyclic aromatic compounds (e.