The zero order regular approximation for relativistic effects: the effect of spin-orbit coupling in closed shell molecules.

In this paper we will calculate the effect of spin–orbit coupling on properties of closed shell molecules, using the zero‐order regular approximation to the Dirac equation. Results are obtained using density functionals including density gradient corrections. Close agreement with experiment is obtained for the calculated molecular properties of a number of heavy element diatomic molecules

Public Transportation Use and Cognitive Function in Older Age: A Quasiexperimental Evaluation of the Free Bus Pass Policy in the United Kingdom

In this quasiexperimental study, we examined whether the introduction of an age-friendly transportation policy- free bus passes for older adults-increased public transport use and in turn affected cognitive function among older people in England. Data came from 7 waves (2002-2014) of the English Longitudinal Study of Ageing (n = 17,953), which measured total cognitive function, memory, executive function, and processing speed before and after the bus pass was introduced in 2006. The analytical strategy was an instrumental-variable approach with fixed effects, which made use of the age-eligibility criteria for free bus passes and addressed bias due to reverse causality, measurement error, and time-invariant confounding. Eligibility for the bus pass was associated with a 7% increase in public transport use. The increase in public transportation use was associated with a 0.346 (95% confidence interval: 0.017, 0.674) increase in the total cognitive function z score and with a 0.546 (95% confidence interval: 0.111, 0.982) increase in memory z score. Free bus passes were associated with an increase in public transport use and, in turn, benefits to cognitive function in older age. Public transport use might promote cognitive health through encouraging intellectually, socially, and physically active lifestyles. Transport policies could serve as public health tools to promote cognitive health in aging populations

The authors reply

We thank Blakely et al. (1) for their observations. We welcome their stance that researchers conducting instrumental variable (IV)–fixed-effects (FE) analysis should be wary of potential violations of the exclusion restriction—in our study (2), the assumption that eligibility for the free bus pass only impacts cognitive function through the effect on public transportation use. The exclusion restriction is essentially untestable and must be supported by strong arguments. We argue that Blakely et al.’s concerns do not offer convincing evidence to conclude that the difference in magnitude between our FE estimates and our IV-FE estimates is due to an exclusion restriction violation

Construction of the Foldy-Wouthuysen transformation and solution of the Dirac equation using large components only

It is shown that it is possible to construct, within the framework of a basis set expansion method, the full Foldy–Wouthuysen transformation (i.e., to all orders in the inverse velocity of light) for an arbitrary potential once the Dirac equation has been solved. On this basis an iterative procedure to solve the Dirac equation is suggested that involves only the large component, obviating the time‐consuming (at least in molecular calculations) introduction of large basis sets for a proper description of just the small components. The methods are used to compare the expectation value of the radial distance operator in the Dirac picture and in the Schrödinger picture for the orbitals of the Uranium atom

Quantification of 3D microstructural parameters of trabecular bone is affected by the analysis software

Over the last decades, the use of high-resolution imaging systems to assess bone microstructural parameters has grown immensely. Yet, no standard defining the quantification of these parameters exists. It has been reported that different voxel size and/or segmentation techniques lead to different results. However, the effect of the evaluation software has not been investigated so far. Therefore, the aim of this study was to compare the bone microstructural parameters obtained with two commonly used commercial software packages, namely IPL (Scanco, Switzerland) and CTan (Bruker, Belgium). We hypothesized that even when starting from the same segmented scans, different software packages will report different results. Nineteen trapezia and nineteen distal radii were scanned at two resolutions (20 mu m voxel size with microCT and HR-pQCT 60 mu m). The scans were segmented using the scanners' default protocol. The segmented images were analyzed twice, once with IPL and once with CTan, to quantify bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N) and specific bone surface (BS/BV). Only small differences between IPL and CTan were found for BV/TV. For Tb.Th, Tb.Sp and BS/BV high correlations (R-2 >= 0.99) were observed between the two software packages, but important relative offsets were observed. For microCT scans, the offsets were relative constant, e.g., around 15% for Tb.Th. However, for the HR-pQCT scans the mean relative offsets ranged over the different bone samples (e.g., for Tb.Th from 14.5% to 19.8%). For Tb.N, poor correlations (0.43 We conclude that trabecular bone microstructural parameters obtained with IPL and CTan cannot be directly compared except for BV/TV. For Tb.Th, Tb.Sp and BS/BV, correction factors can be determined, but these depend on both the image voxel size and specific anatomic location. The two software packages did not produce consistent data on Tb.N. The development of a universal standard seems desirable

Embracing ligands. Synthesis, characterisation and the correlation between 59Co NMR and ligand field parameters of Co(III) complexes with a new class of nitrogen-thioether multidentate ligand

The syntheses of the hexadentate ligands 2,2,10,10-tetra(methyleneamine)-4,8-dithiaundecane (PrN(4)S(2)amp), 2,2,11,11-tetra(methyleneamine)-4,9-dithiadodecane (BuN(4)S(2)amp), and 1,2-bis(4,4-methyleneamine)-2-thiapentyl)benzene (XyN(4)S(2)amp) are reported and the complexes [Co(RN(4)S(2)amp)](3+) (R = Pr, Bu, Xy) characterised by single crystal X-ray study. The low-temperature (11 K) absorption spectra have been measured in Nafion films. From the observed positions of both spin-allowed (1)A(1g) --> T-1(1g) and (1)A(1g) --> T-1(2g) and spin forbidden (1)A(1g) --> T-3(1g) and (1)A(1g) --> T-3(2g) bands, octahedral ligand-field parameters (10D(q), B and C) have been determined. DFT calculations suggest that significant interaction between the d-d and CT excitations occurs for the complexes. The calculations offer an explanation for the observed deviations from linearity of the relationship between Co-59 magnetogyric ratio and beta(DeltaE)(-1) (beta = the nephelauxetic ratio; DeltaE the energy of the (1)A(1g) --> T-1(1g) transition) for a series of amine and mixed amine/thioether donor complexes

High-Resolution Cone-Beam Computed Tomography is a Fast and Promising Technique to Quantify Bone Microstructure and Mechanics of the Distal Radius

Obtaining high-resolution scans of bones and joints for clinical applications is challenging. HR-pQCT is considered the best technology to acquire high-resolution images of the peripheral skeleton in vivo, but a breakthrough for widespread clinical applications is still lacking. Recently, we showed on trapezia that CBCT is a promising alternative providing a larger FOV at a shorter scanning time. The goals of this study were to evaluate the accuracy of CBCT in quantifying trabecular bone microstructural and predicted mechanical parameters of the distal radius, the most often investigated skeletal site with HR-pQCT, and to compare it with HR-pQCT. Nineteen radii were scanned with four scanners: (1) HR-pQCT (XtremeCT, Scanco Medical AG, @ (voxel size) 82 mu m), (2) HR-pQCT (XtremeCT-II, Scanco, @60.7 mu m), (3) CBCT (NewTom 5G, Cefla, @75 mu m) reconstructed and segmented using in-house developed software and (4) microCT (VivaCT40, Scanco, @19 mu m-gold standard). The following parameters were evaluated: predicted stiffness, strength, bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), separation (Tb.Sp) and number (Tb.N). The overall accuracy of CBCT with in-house optimized algorithms in quantifying bone microstructural parameters was comparable (R-2 = 0.79) to XtremeCT (R-2 = 0.76) and slightly worse than XtremeCT-II (R-2 = 0.86) which were both processed with the standard manufacturer's technique. CBCT had higher accuracy for BV/TV and Tb.Th but lower for Tb.Sp and Tb.N compared to XtremeCT. Regarding the mechanical parameters, all scanners had high accuracy (R-2 >= 0.96). While HR-pQCT is optimized for research, the fast scanning time and good accuracy renders CBCT a promising technique for high-resolution clinical scanning

Компьютерная томография и магнитно-резонансная томография в диагностике опухолей средостения

Резюме. Проанализированы результаты обследования 95 больных с опухолями средостения (ОС) с использованием рентгенологических методов: компьютерной томографии (КТ), магнитно-резонансной томографии (МРТ). Приведена КТ- и МРТ-семиотика ОС, оценена информативность результатов каждого метода в зависимости от локализации опухоли. На основании полученных данных обоснованы показания к применению и последовательность использования неинвазивных лучевых методов в целях диагностики ОС. В частности, МРТ наиболее показана при локализации опухоли в заднем и передневерхнем отделах средостения, тогда как КТ целесообразнее проводить, если опухоль располагается в переднесреднем, передненижнем или среднем отделах средостения. Ключевые слова: опухоли средостения, рентгенологическое исследование, компьютерная томография, магнитно-резонансная томография, диагностическая эффективность.Summary. The paper reports findings of examination of 95 patients with mediastinum tumors (MS) using the following roentgenologic methods: computed tomography (CT) and magnetic resonance tomography (MRT). CR and MRT semeiology of MS is described and the informative value of each method is assessed in dependence on tumor’s localization. Based on these findings, indications for application of non-invasive radiation methods in examination of mediastinum tumors are developed as well as the sequence of their using. In particular, MRT is especially promising in tumors localized in posterior and antero-superior portions of the mediastinum, while CT is more appropriate in tumors localized in antero-medial, antero-lower or medial portions of the mediastinum. Key Words: mediastinum tumors, roentgenologic examination, computed tomography, magnetic resonance tomography, diagnostic efficiency