Search query: on the accuracy o commonly used density rasander

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abstract: We have performed density functional calculations using a range of local and semi local as well as hybrid density functional approximations of the structure and elastic constants of 18 semiconductors and insulators. We find that most of the approximations have a very small error in the lattice constants, of the order of 1% while the errors in the elastic constants and bulk modulus are much larger, at about 10% or better. When comparing experimental and theoretical lattice constants and bulk modulus we have included zero point phonon effects. These effects make the experimental reference lattice constants 0.019 A smaller on average while making the bulk modulus 4.3 GPa stiffer on average. According to our study, the overall best performing density functional approximations for determining the structure and elastic properties are the PBEsol functional, the two hybrid density functionals PBE0 and HSE (Heyd, Scuseria, and Ernzerhof) as well as the AM05 functional.
author_names: Mikael Rasander

Michelle A Moram
title: On the accuracy of commonly used density functional approximations in determining the elastic constants of insulators and semiconductors.
venue: The Journal of chemical physics
year: 2015

abstract: BACKGROUND Improved patient comfort and optimal glycemic control have led to the widespread use of insulin pens, particularly in Europe. Most of the former studies on the dose accuracy of insulin pens included only a small number of doses and pens. In extension to our previous large scale study testing the dosing accuracy following a randomized dosing sequence with each pen, the present study was more directed toward the dose accuracy for one specific dose dispensed repeatedly with the same pen. This is the first study providing detailed comparative data on the accuracy of repeated dose delivery with prefilled disposable insulin pens at low, middle, and high doses, dispensed over the entire pen volume. MATERIALS AND METHODS In total, 15 previously unused insulin pens from two lots of each pen type (SoloSTAR((r) [sanofi aventis, Paris, France] FlexPen((r) [Novo Nordisk A/S, Bagsvaerd, Denmark] Next Generation FlexPen [Novo Nordisk] and KwikPen(tm) [Eli Lilly, Indianapolis, IN] were used to deliver 5 unit (low) 30 unit (middle) and 60 unit (high) doses, respectively, dispensed four times from each pen in a nonrandomized manner. Actual doses were determined gravimetrically taking the density of the respective insulin into account and were evaluated according to the guidelines (DIN EN ISO 11608 1:2000) of the International Organization for Standardization (ISO) RESULTS All tested insulin pens met the requirements for accuracy with none of the single values being outside the defined range of the ISO recommendations (1+ 1 units, 30+ 1.5 units, and 60+ 3 units, respectively) CONCLUSION The present study demonstrated a consistent and accurate dose delivery at all dosage levels for all tested insulin pens, with no clinically relevant differences among the products.
author_names: Meike Krzywon

Thomas van der Burg

Uwe Fuhr

Manfred Schubert-Zsilavecz

Mona Abdel-Tawab
title: Study on the dosing accuracy of commonly used disposable insulin pens.
venue: Diabetes technology therapeutics
year: 2012

abstract: Abstract Objective: The present study aimed to assess the dosing accuracy of commonly used disposable insulin pens including SoloStar (SR) FlexPen (FP) Next Generation FlexPen (NGFP) and KwikPen (KP) It is the first comparative study covering the whole dosing range from 1 U to 60 U. It also covers the accuracy of SR at 80 U. SoloStar (SR) is a registered trademark of sanofi aventis. FlexPen (FP) and Next Generation FlexPen (NGFP) are registered trademarks of Novo Nordisk A/S. KwikPen (KP) is a registered trademark of Eli Lilly. Research design and method: A total of sixty insulin pens from two lots of each pen type were used. From each pen 1 U, 10 U, 30 U, 40 U, 60 U and 80 U were dispensed in random order. The 80 U dose was only evaluated for the SR as the other insulin pens do not deliver this dose in one injection. The actual doses were determined gravimetrically taking density of the different insulin preparations into account. The evaluation of dose accuracy was based on the regulations of the International Organization for Standardization (DIN EN ISO 11608 1:2000) Results: All tested insulin pens met the requirements for accuracy with none of the single values at all dose levels being outside the defined range of the ISO recommendations (1 1 U, 10 1 U, 30 1.5 U, 40 2 U, 60 3 U and 80 4 U) For the investigated dosage levels the absolute average deviation of all insulin pens ranged between 0.09 and 0.81 U. Conclusion: The present study demonstrates an excellent dosing accuracy for all tested insulin pens, with no clinically relevant differences between the products.
author_names: Meike Krzywon

Mona Abdel-Tawab

Thomas van der Burg

Uwe Fuhr

Manfred Schubert-Zsilavecz
title: Dosing accuracy of commonly used disposable insulin pens
venue: Current medical research and opinion
year: 2010

abstract: Importance Accurate long term breast cancer risk assessment for women attending routine screening could help reduce the disease burden and intervention associated harms by personalizing screening recommendations and preventive interventions. Objective To report the accuracy of risk assessment for breast cancer during a period of 19 years. Design, Setting, and Participants This cohort study of the Kaiser Permanente Washington breast imaging registry included women without previous breast cancer, aged 40 to 73 years, who attended screening from January 1, 1996, through December 31, 2013. Follow up was completed on December 31, 2014, and data were analyzed from March 2, 2016, through November 13, 2017. Exposures Risk factors from a questionnaire and breast density from the Breast Imaging and Reporting Data System at entry; primary risk was assessed using the Tyrer Cuzick model. Main Outcomes and Measures Incidence of invasive breast cancer was estimated with and without breast density. Follow up began 6 months after the entry mammogram and extended to the earliest diagnosis of invasive breast cancer, censoring at 75 years of age, 2014, diagnosis of ductal carcinoma in situ, death, or health plan disenrollment. Observed divided by expected (O/E) numbers of cancer cases were compared using exact Poisson 95% CIs. Hazard ratios for the top decile of 10 year risk relative to the middle 80% of the study population were estimated. Constancy of relative risk calibration during follow up was tested using a time dependent proportional hazards effect. Results In this cohort study of 132 139 women (median age at entry, 50 years; interquartile range, 44 58 years) 2699 invasive breast cancers were subsequently diagnosed after a median 5.2 years of follow up (interquartile range, 2.4 11.1 years; maximum follow up, 19 years; annual incidence rate [IR] per 1000 women, 2.9) Observed number of cancer diagnoses was close to the expected number (O/E for the Tyrer Cuzick model, 1.02 [95% CI, 0.98 1.06] O/E for the Tyrer Cuzick model with density, 0.98 [95% CI, 0.94 1.02] The Tyrer Cuzick model estimated 2554 women (1.9% to be at high risk (10 year risk of =8% of whom 147 subsequently developed invasive breast cancer (O/E, 0.79; 95% CI, 0.67 0.93; IR per 1000 women, 8.7) The Tyrer Cuzick model with density estimated more women to be at high risk (4645 [3.5% 273 cancers [10.1% O/E, 0.78; 95% CI, 0.69 0.88; IR per 1000 women, 9.2) The hazard ratio for the highest risk decile compared with the middle 80% was 2.22 (95% CI, 2.02 2.45) for the Tyrer Cuzick model and 2.55 (95% CI, 2.33 2.80) for the Tyrer Cuzick model with density. Little evidence was found for a decrease in relative risk calibration throughout follow up for the Tyrer Cuzick model (age adjusted slope, 0.003; 95% CI, 0.018 to 0.012) or the Tyrer Cuzick model with density (age adjusted slope, 0.008; 95% CI, 0.020 to 0.004) Conclusions and Relevance Breast cancer risk assessment combining classic risk factors with mammographic density may provide useful data for 10 years or more and could be used to guide long term, systematic, risk adapted screening and prevention strategies.
author_names: Adam R Brentnall

Jack M Cuzick

Diana S M Buist

Erin J Aiello Bowles
title: Long term Accuracy of Breast Cancer Risk Assessment Combining Classic Risk Factors and Breast Density
venue: JAMA oncology
year: 2018

abstract: We perform extensive benchmark comparisons of surface hopping dynamics with numerically exact calculations for the spin boson model over a wide range of energetic and coupling parameters as well as temperature. We find that deviations from golden rule scaling in the Marcus regime are generally small and depend sensitively on the energetic bias between electronic states. Fewest switches surface hopping (FSSH) is found to be surprisingly accurate over a large swath of parameter space. The inclusion of decoherence corrections via the augmented FSSH algorithm improves the accuracy of dynamical behavior compared to exact simulations, but the effects are generally not dramatic, at least for the case of an environment modeled with the commonly used Debye spectral density.
author_names: Hsing-Ta Chen

David R Reichman
title: On the accuracy of surface hopping dynamics in condensed phase non adiabatic problems.
venue: The Journal of chemical physics
year: 2016

abstract: Abstract Background An accurate model to stratify breast cancer risk is required to move from a one size fits all screening paradigm to more personalised risk based screening strategies. Most risk models have limited accuracy and have been calibrated for white women. Considering the rapid increase in breast cancer incidence in China, in this study we aimed to develop a breast cancer model for Chinese women. Methods We recruited women from Fudan University Shanghai Cancer Centre. Information about their height, weight, body mass index, age at menarche, age at first delivery, age at menopause, menopause status, parity history, number of children, breastfeeding history, personal history of breast cancer, family history of breast cancer, and degree of consanguinity was obtained. Mammograms were acquired from all recruited women. We used AutoDensity software to segment the mammographic dense area. To ensure that the breast density had not been affected by presence of the lesion, we measured the mammographic breast density of patients with cancer from the cancer free breast contralateral to the biopsy proven cancer. The breast area, dense area, percentage density, and demographic variables were input into an ensemble of 50 decision trees, the results of which we combined using a hybrid sampling and boosting algorithm (RUSBoost) The variables were also fed into the logistic and stepwise logistic regression models, which are two commonly used linear models. Leave one out cross validation was used to assess the performance of the models and the receiver operating characteristics (ROC) curves were generated for each model. Findings In total, 1079 women (85 women with biopsy proven breast cancer and 994 women without breast cancer) were recruited. The classifier had an area under ROC curve (AUC) of 0*86 (95% CI 0*82 0*89) for classifying the cases as normal or high risk. It outperformed the accuracy of traditionally employed logistic and stepwise logistic regression models, which resulted in AUC values of 0*739 (0*67 0*81) and 0*757 (0*69 0*81) respectively. Interpretation When compared with linear models, use of a machine learning approach, which models data non linearity, could lead to improvement in the accuracy of a breast cancer risk stratification model. Such a model can be used to recommend intensified surveillance for women at a high risk of future breast cancer. Funding None.
author_names: Ziba Gandomkar

Tong Li

Zhi-Ming Shao

L Tang

Qin Xiao

Yajia Gu

Gen-Hong Di

Claudia R Mello-Thoms

Patrick C Brennan
title: A machine learning approach for stratifying breast cancer risk in Chinese women on the basis of epidemiological factors and mammographic density
venue: The Lancet
year: 2019

abstract: Significance Numerous empirical studies in population genetics have used a summary statistic called the sample frequency spectrum (SFS) which summarizes the information in a sample of DNA sequences. Despite their popularity, the accuracy of inference methods based on the SFS is difficult to characterize theoretically, and it is currently unknown how the estimation accuracy improves as more sites in the genome are used. Here, we establish information theoretic limits on the accuracy of all estimators that use the SFS to infer population size histories. We study the rate of convergence to the true answer as the amount of data increases, and obtain the surprising result that it is exponentially worse than known convergence rates for many classical estimation problems in statistics. The sample frequency spectrum (SFS) of DNA sequences from a collection of individuals is a summary statistic that is commonly used for parametric inference in population genetics. Despite the popularity of SFS based inference methods, little is currently known about the information theoretic limit on the estimation accuracy as a function of sample size. Here, we show that using the SFS to estimate the size history of a population has a minimax error of at least O(1/log s) where s is the number of independent segregating sites used in the analysis. This rate is exponentially worse than known convergence rates for many classical estimation problems in statistics. Another surprising aspect of our theoretical bound is that it does not depend on the dimension of the SFS, which is related to the number of sampled individuals. This means that, for a fixed number s of segregating sites considered, using more individuals does not help to reduce the minimax error bound. Our result pertains to populations that have experienced a bottleneck, and we argue that it can be expected to apply to many populations in nature.
author_names: Jonathan Terhorst

Yun S Song
title: Fundamental limits on the accuracy of demographic inference based on the sample frequency spectrum
venue: Proceedings of the National Academy of Sciences
year: 2015

abstract: Integral equation theories provide an efficient route for computing the solvation free energy (SFE) of molecular systems in water. The accuracy of those theories is usually tested against small molecules via comparison of SFE with reference data. However, tests against larger molecules in the nanometer regime are scarce in literature despite recent applications to such systems. Here, we thus study the accuracy and validity of a commonly used integral equation theory, namely, a three dimensional reference interaction site model (3D RISM) by considering the following problems: (1) solvation of a small to large Lennard Jones particle, (2) binding of planar hydrophobic systems with varying size and hydrophobicity, and (3) self assembly of amphiphilic molecules into a nanocapsule. The energy representation method is also utilized for comparison. The results show that the 3D RISM method works successfully for small molecules, while the accuracy degrades systematically with system size and hydrophobicity. The size dependent error in SFE does not cancel adequately between two solute configurations, resulting in a substantial error in the free energy difference. It is also shown that the free energy profiles for hydrophobic association exhibit a fictitious high energy barrier, suggesting that care must be taken for studying such systems. The numerical difficulties observed above are discussed based on the relation between hypernetted chain approximation, classical density functional theory with quadratic expansion, and the size dependent error arising from the cavity region of the system.
author_names: Takatoshi Fujita

Takeshi Yamamoto
title: Assessing the accuracy of integral equation theories for nano sized hydrophobic solutes in water.
venue: The Journal of chemical physics
year: 2017

abstract: We have investigated the suitability of Time Dependent Density Functional Theory (TD DFT) to describe vertical low energy excitations in naked and hydrated titanium dioxide nanoparticles. Specifically, we compared TD DFT results obtained using different exchange correlation (XC) potentials with those calculated using Equation of Motion Coupled Cluster (EOM CC) quantum chemistry methods. We demonstrate that TD DFT calculations with commonly used XC potentials (e.g. B3LYP) and EOM CC methods give qualitatively similar results for most TiO2 nanoparticles investigated. More importantly, however, we also show that, for a significant subset of structures, TD DFT gives qualitatively different results depending upon the XC potential used and that only TD CAM B3LYP and TD BHLYP calculations yield results that are consistent with those obtained using EOM CC theory. Moreover, we demonstrate that the discrepancies for such structures originate from a particular combination of defects that give rise to charge transfer excitations, which are poorly described by XC potentials that do not contain sufficient Hartree Fock like exchange. Finally, we consider that such defects are readily healed in the presence of ubiquitously present water and that, as a result, the description of vertical low energy excitations for hydrated TiO2 nanoparticles is nonproblematic.
author_names: Enrico Berardo

Han-Shi Hu

Stephen Andrew Shevlin

Scott M Woodley

Karol Kowalski

Martijn A Zwijnenburg
title: Modeling Excited States in TiO2 Nanoparticles: On the Accuracy of a TD DFT Based Description
venue: Journal of chemical theory and computation
year: 2014

abstract: Meteorological drought indices are commonly calculated using data from weather stations and then interpolated to create a map of moisture conditions. These maps are used to communicate drought information to decision makers and the general public. This study analyzes five of the factors (drought index, interpolation method, seasonality, climate region, and station density) that influence the accuracy of these maps. This study compared the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) using data from the Cooperative Observer Network (COOP) and United States Historical Climatology Network (USHCN) The accuracy of the drought maps varied significantly over time and space. The most significant factor affecting the accuracy of the meteorological drought maps was seasonality. Errors were higher in regions (e.g. southeastern U.S. and months (e.g. summer) dominated by convective precipitation. The choice of interpolation method also had an influence. We found that Ordinary Kriging (OK) performed better than Inverse Distance Weighting (IDW) in all cases and therefore it was recommended for interpolating drought indices. Not surprisingly, maps that were created using more stations (COOP) were more accurate. The normalized errors of SPI and SPEI were very similar and so the choice of drought index had little impact on the accuracy of the drought maps.
author_names: Shanshui Yuan

Steven M Quiring

S Patil
title: Spatial and temporal variations in the accuracy of meteorological drought indices
venue: CIG 2016
year: 2016