Accurate and efficient linear scaling DFT calculations with universal applicability

Density Functional Theory calculations traditionally suffer from an inherent cubic scaling with respect to the size of the system, making big calculations extremely expensive. This cubic scaling can be avoided by the use of so-called linear scaling algorithms, which have been developed during the last few decades. In this way it becomes possible to perform ab-initio calculations for several tens of thousands of atoms or even more within a reasonable time frame. However, even though the use of linear scaling algorithms is physically well justified, their implementation often introduces some small errors. Consequently most implementations offering such a linear complexity either yield only a limited accuracy or, if one wants to go beyond this restriction, require a tedious fine tuning of many parameters. In our linear scaling approach within the BigDFT package, we were able to overcome this restriction. Using an ansatz based on localized support functions expressed in an underlying Daubechies wavelet basis -- which offers ideal properties for accurate linear scaling calculations -- we obtain an amazingly high accuracy and a universal applicability while still keeping the possibility of simulating large systems with only a moderate demand of computing resources

Bulking agents: an analysis of 500 cases and review of the literature

Introduction and hypothesis: Stress urinary incontinence (SUI) is common, impacts women's quality of life, and generates high costs. Physiotherapy is the first-line therapy, and if it fails, suburethral slings are the gold standard in SUI surgery. Bulking agents injected periurethrally might be a beneficial alternative, but there is a paucity of data on bulking therapy. The aim of this study was to prospectively analyze the efficacy and safety of bulking agents in the setting of a tertiary referral center. Methods: In the last 13years, 514 elderly women with SUI were treated by injection therapy with either collagen (Contigen®), hyaluronic acid (Zuidex®), ethylene vinyl alcohol (Tegress®), or polyacrylamide hydrogel (Bulkamid®). Subjective and objective outcome was recorded at the 12-month postoperative appointment using the King's Health Questionnaire, visual analogue scale (VAS) describing their incontinence severity, standardized pad test, and urethral pressure profile. Results: Demographic data were equally distributed in all four groups of agents used. Sixty-one patients were lost to follow-up (10.6%). Statistically significant changes were found for maximum urethral closure pressure (MUCP), pad weight, and VAS before and after bulking for the four agents used. Pad test was negative in 73.2% of patients after bulking therapy. Subjective assessment showed improvements in general health and role limitations. The overall complication rate was low for all agents. Conclusions: This study shows improvement in incontinence after bulking therapy according to subjective and objective outcomes in an elderly population. In contrast to earlier reports, side effects due to injections were few and mild. We can advocate bulking therapy for treating SUI, as it is simple, safe, and shows both objective and subjective improvement and relie

Action Semantic Deficits and Impaired Motor Skills in Autistic Adults Without Intellectual Impairment

Several studies indicate the functional importance of the motor cortex for higher cognition, language and semantic processing, and place the neural substrate of these processes in sensorimotor action-perception circuits linking motor, sensory and perisylvian language regions. Interestingly, in individuals with autism spectrum disorder (ASD), semantic processing of action and emotion words seems to be impaired and is associated with hypoactivity of the motor cortex during semantic processing. In this study, the relationship between semantic processing, fine motor skills and clinical symptoms was investigated in 19 individuals with ASD and 22 typically-developing matched controls. Participants completed two semantic decision tasks involving words from different semantic categories, a test of alexithymia (the Toronto Alexithymia Scale), and a test of fine motor skills (the Purdue Pegboard Test). A significant Group × Word Category interaction in accuracy (p < 0.05) demonstrated impaired semantic processing for action words, but not object words in the autistic group. There was no significant group difference when processing abstract emotional words or abstract neutral words. Moreover, our study revealed deficits in fine motor skills as well as evidence for alexithymia in the ASD group, but not in neurotypical controls. However, these motor deficits did not correlate significantly with impairments in action-semantic processing. We interpret the data in terms of an underlying dysfunction of the action-perception system in ASD and its specific impact on semantic language processing

Metrics for measuring distances in configuration spaces

In order to characterize molecular structures we introduce configurational fingerprint vectors which are counterparts of quantities used experimentally to identify structures. The Euclidean distance between the configurational fingerprint vectors satisfies the properties of a metric and can therefore safely be used to measure dissimilarities between configurations in the high dimensional configuration space. We show that these metrics correlate well with the RMSD between two configurations if this RMSD is obtained from a global minimization over all translations, rotations and permutations of atomic indices. We introduce a Monte Carlo approach to obtain this global minimum of the RMSD between configurations

Laparoscopic sacrocolpopexy mesh excision step-by-step.

INTRODUCTION AND HYPOTHESIS The objective was to demonstrate the surgical procedure of laparoscopic mesh removal after sacrocolpopexy to aid clinicians facing mesh complications. METHODS Video footage shows the laparoscopic management of mesh failure and mesh erosion after sacrocolpopexy with narrated video sequences of two patients. RESULTS Laparoscopic sacrocolpopexy represents the gold standard in advanced prolapse repair. Mesh complications occur infrequently but infections, failure of prolapse repair and mesh erosions necessitate mesh removal and repeat sacrocolpopexy if applicable. The video deals with two women referred to our tertiary referral urogynecology unit in the University Women's Hospital of Bern, Switzerland, after laparoscopic sacrocolpopexies that were carried out in remote hospitals. Both patients were asymptomatic more than 1 year after surgery. CONCLUSIONS Complete mesh removal after sacrocolpopexy and repeat prolapse surgery can be challenging but is feasible and is aimed at improving patients' complaints and symptoms

Daubechies Wavelets for Linear Scaling Density Functional Theory

We demonstrate that Daubechies wavelets can be used to construct a minimal set of optimized localized contracted basis functions in which the Kohn-Sham orbitals can be represented with an arbitrarily high, controllable precision. Ground state energies and the forces acting on the ions can be calculated in this basis with the same accuracy as if they were calculated directly in a Daubechies wavelets basis, provided that the amplitude of these contracted basis functions is sufficiently small on the surface of the localization region, which is guaranteed by the optimization procedure described in this work. This approach reduces the computational costs of DFT calculations, and can be combined with sparse matrix algebra to obtain linear scaling with respect to the number of electrons in the system. Calculations on systems of 10,000 atoms or more thus become feasible in a systematic basis set with moderate computational resources. Further computational savings can be achieved by exploiting the similarity of the contracted basis functions for closely related environments, e.g. in geometry optimizations or combined calculations of neutral and charged systems