Speaking Fundamental Frequency in Monozygotic and Dizygotic Twins

The speaking fundamental frequency (SFF) and the intraindividual variation of the SFF during the reading of a Dutch standard text were measured in 30 female monozygotic twins (MT) and 30 dizygotic twins (DT), aged 15–29 years. A control group was created that consisted of 30 nonrelated paired individuals of equal age. Studying the intrapair correlation coefficients it seemed that the SFF was similar to a greater degree in MT and to a lesser degree in DT, while there was no correlation at all in nonrelated peers. These results are compatible with a genetic basis for the SFF. On the other hand, the intraindividual variation of the SFF was highly similar in MT and in DT (but not in nonrelated peers), so that for this parameter it was not possible to discern the influences of genetic disposition and shared environment.     

A process analytical approach for quality control of dapivirine in HIV preventive vaginal rings by Raman spectroscopy

An estimated 34 million people are living with human immunodeficiency virus (HIV) worldwide. A polymeric drug delivery device for women has been developed to help reduce male to female vaginal transmission of HIV‐1. The device is an intravaginal slow‐release ring containing the antiretroviral drug dapivirine as the active pharmaceutical ingredient (API). In all pharmaceutical delivery systems, API content is a critical control point. Conventional quantification of the API in vaginal rings is a stepwise, destructive and time‐consuming process involving solvent extraction and high pressure liquid chromatography. This study investigates the potential of Raman spectroscopy for fast and non‐destructive quantification of dapivirine in intravaginal rings. Wide‐area illumination measurements were carried out on rotating rings using a custom built ring spinner. Customized reference rings of known concentrations were used to build calibration models, and the models were verified by rings from production using the established method as reference analysis. Bi‐ and multivariate calibration methods were applied. Models based on band ratios and partial least squares (PLS) regression models performed similarly well resulting in low model and prediction errors. Next to an alternative reference analysis for quality assurance, Raman can also be used as a production process performance analysis and optimization tool due to its non‐destructive nature and speed of analysis. Using measurements on connected spots over the entire ring circumference, the within ring variation in API was determined. ANOVA showed that there was a statistical difference in API distribution over the rings, information that can be of use in process optimization, for example. However, Tukey's honestly significant difference (HSD) test proved that no regions of the ring were out of specifications, indicating a stable production system. Copyright © 2014 John Wiley & Sons, Ltd.     

Deep metastable eutectic nanometer-scale particles in the MgO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> system

Laboratory vapor phase condensation experiments systematically yield amorphous, homogeneous, nanoparticles with unique deep metastable eutectic compositions. They formed during the nucleation stage in rapidly cooling vapor systems. These nanoparticles evidence the complexity of the nucleation stage. Similar complex behavior may occur during the nucleation stage in quenched-melt laboratory experiments. Because of the bulk size of the quenched system many of such deep metastable eutectic nanodomains will anneal and adjust to local equilibrium but some will persist metastably depending on the time–temperature regime and melt/glass transformation.     

Layers and matroids for the traveling salesman’s paths

Gottschalk and Vygen proved that every solution of the subtour elimination linear program for traveling salesman paths is a convex combination of more and more restrictive “generalized Gao-trees”. We give a short proof of this fact, as a layered convex combination of bases of a sequence of increasingly restrictive matroids. A strongly polynomial, combinatorial algorithm follows for finding this convex combination, which is a new tool offering polyhedral insight, already instrumental in recent results for the $s?t$ path TSP.     

Perpendicular ultrasound velocity measurement by 2D cross correlation of RF data. Part B: volume flow estimation in curved vessels

A novel axial velocity profile integration method, obtained from ultrasonic perpendicular velocimetry, for flow estimation in curved tubes was validated. In an experimental set-up, physiologically relevant curved geometries and flows were considered. Axial velocity profile measurements were taken by applying particle imaging velocimetry-based methods to ultrasound data acquired by means of a linear array transducer positioned perpendicular to the axial velocity component. Comparison of the assessed asymmetric velocity profiles to computational fluid dynamics calculations showed excellent agreement. Subsequently, the recently introduced cos θ-integration method for flow estimation was compared to the presently applied Poiseuille and Womersley models. The average deviation between the cos θ-integration-based unsteady flow estimate and the reference flow was about 5%, compared to an average deviation of 20% for both the Poiseuille and Womersley approximation. Additionally, the effect of off-centre measurement was analysed for the three models. It was found that only for the cos θ-integration method, an accurate flow estimation is feasible, even when it is measured off centre.     

Fast and Quantitative NMR Metabolite Analysis Afforded by a Paramagnetic Co‐Solute

NMR spectroscopy is an indispensable technique for the determination of the chemical identity and structure of small molecules. The method is especially recognized for its robustness and intrinsically quantitative nature, and has manifested itself as a key analytical platform for diverse fields of application, ranging from chemical synthesis to metabolomics. Unfortunately, the slow recovery of nuclear spin polarization by spin‐lattice (T₁) relaxation causes most experimental time to be lost on idle waiting. Furthermore, truly quantitative NMR (qNMR) spectroscopy requires waiting times of 5‐times the longest T₁ in the sample, making qNMR spectroscopy slow and inefficient. We demonstrate here that co‐solute paramagnetic relaxation can mitigate these two problems simultaneously. The addition of a small amount of paramagnetic gadolinium chelate, available in the form of commercial contrast‐agent solutions, enables cheap, quantitative, and efficient high‐throughput mixture analysis.     

Enhancements in full‐field PIXE imaging—Large area elemental mapping with increased lateral resolution devoid of optics artefacts

The combination of a pn‐junction charge‐coupled device‐based pixel detector with a poly‐capillary X‐ray optics was installed and examined at the Helmholtz‐Zentrum Dresden‐Rossendorf. The set‐up is intended for particle‐induced X‐ray emission imaging to survey the trace elemental composition of flat/polished geological samples. In the standard configuration, a straight X‐ray optics (20 μm capillary diameter) is used to guide the emitted photons from the sample towards the detector with nearly 70 000 pixels. Their dimensions of 48 × 48 μm² are the main limitation of the lateral resolution. This limitation can be bypassed by applying a dedicated subpixel algorithm to recalculate the footprint of the photon's electron cloud in the detector. The lateral resolution is then mainly determined by the capillary's diameter. Nevertheless, images are still superimposed by the X‐ray optics pattern. The optics' capillaries are grouped in hexagonal bundles resulting in a reduced transmission of X‐rays in the boundary regions. This influence can be largely suppressed by combining a series of short measurements at slightly shifted positions using a precision stage and correcting the image data for this shifting. The use of a subpixel grid for the image reconstruction allows a further increase of the spatial resolution. This approach of image‐stacking and multiframe super‐resolution in combination with the subpixel correction algorithm is presented and illustrated with experimental data. Additionally, a flat‐field correction is shown to remove the remaining imaging inhomogeneity caused by non‐uniform X‐ray transmission. The described techniques can be used for all X‐ray spectrometry methods using an X‐ray camera to obtain high‐quality elemental images.     

Density functional theory study of the near edge X-ray absorption fine structure and infrared spectroscopy of acetylene and benzene on group IV semiconductor surfaces

The near edge X-ray absorption fine structure and infrared spectroscopy of acetylene and benzene adsorbed on C(1 0 0)-2 × 1, Si(1 0 0)-2 × 1 and Ge(1 0 0)-2 × 1 surfaces is studied with density functional theory calculations. Time dependent density functional theory calculations of the near edge X-ray absorption fine structure with a modified exchange-correlation functional agree well with experiment, and show that the spectral features arise from excitation to π^∗, and orbitals, where X represents C, Si or Ge. The excitation energies are dependent on the surface, and for acetylene, the location of the π^∗ band also varies with the surface. Calculations of the vibrational modes show the CH stretching frequencies for carbon atoms bonded directly to the surface vary significantly between the three surfaces, while those for carbon atoms not bonded to the surface do not change significantly.     

High-energy collision of two black holes

We study the head-on collision of two highly boosted equal mass, nonrotating black holes. We determine the waveforms, radiated energies, and mode excitation in the center of mass frame for a variety of boosts. For the first time we are able to compare analytic calculations, black-hole perturbation theory, and strong field, nonlinear numerical calculations for this problem. Extrapolation of our results, which include velocities of up to 0.94c, indicate that in the ultrarelativistic regime about 14+/-3% of the energy is converted into gravitational waves. This gives rise to a luminosity of order 10_(-2)c_(5)/G, the largest known so far in a black-hole merger.