Generation of Large Vortex-Free Superfluid Helium Nanodroplets.

Superfluid helium nanodroplets are an ideal environment for the formation of metastable, self-organized dopant nanostructures. However, the presence of vortices often hinders their formation. Here, we demonstrate the generation of vortex-free helium nanodroplets and explore the size range in which they can be produced. From x-ray diffraction images of xenon-doped droplets, we identify that single compact structures, assigned to vortex-free aggregation, prevail up to 10^{8} atoms per droplet. This finding builds the basis for exploring the assembly of far-from-equilibrium nanostructures at low temperatures.

Three-dimensional femtosecond snapshots of isolated faceted nanostructures.

The structure and dynamics of isolated nanosamples in free flight can be directly visualized via single-shot coherent diffractive imaging using the intense and short pulses of x-ray free-electron lasers. Wide-angle scattering images encode three-dimensional (3D) morphological information of the samples, but its retrieval remains a challenge. Up to now, effective 3D morphology reconstructions from single shots were only achieved via fitting with highly constrained models, requiring a priori knowledge about possible geometries. Here, we present a much more generic imaging approach. Relying on a model that allows for any sample morphology described by a convex polyhedron, we reconstruct wide-angle diffraction patterns from individual silver nanoparticles. In addition to known structural motives with high symmetries, we retrieve imperfect shapes and agglomerates that were not previously accessible. Our results open unexplored routes toward true 3D structure determination of single nanoparticles and, ultimately, 3D movies of ultrafast nanoscale dynamics.

The Scatman: an approximate method for fast wide-angle scattering simulations.

Single-shot coherent diffraction imaging (CDI) is a powerful approach to characterize the structure and dynamics of isolated nanoscale objects such as single viruses, aerosols, nanocrystals and droplets. Using X-ray wavelengths, the diffraction images in CDI experiments usually cover only small scattering angles of a few degrees. These small-angle patterns represent the magnitude of the Fourier transform of the 2D projection of the sample's electron density, which can be reconstructed efficiently but lacks any depth information. In cases where the diffracted signal can be measured up to scattering angles exceeding ∼10°, i.e. in the wide-angle regime, some 3D morphological information of the target is contained in a single-shot diffraction pattern. However, the extraction of the 3D structural information is no longer straightforward and defines the key challenge in wide-angle CDI. So far, the most convenient approach relies on iterative forward fitting of the scattering pattern using scattering simulations. Here the Scatman is presented, an approximate and fast numerical tool for the simulation and iterative fitting of wide-angle scattering images of isolated samples. Furthermore, the open-source software implementation of the Scatman algorithm, PyScatman, is published and described in detail. The Scatman approach, which has already been applied in previous work for forward-fitting-based shape retrieval, adopts the multi-slice Fourier transform method. The effects of optical properties are partially included, yielding quantitative results for small, isolated and weakly interacting samples. PyScatman is capable of computing wide-angle scattering patterns in a few milliseconds even on consumer-level computing hardware, potentially enabling new data analysis schemes for wide-angle coherent diffraction experiments.

[Fetal Alcohol Spectrum Disorders in Adults - Results from a Diagnostic Outpatient Clinic]. / Fetale Alkoholspektrum-Störungen im Erwachsenenalter ­ Ergebnisse aus einer diagnostischen Sprechstunde.

AIM OF THE STUDY: Fetal alcohol spectrum disorders (FASD) are quite common and, due to the risk of psychiatric comorbidities, highly relevant until adulthood. Diagnostic clarification in adulthood is a prerequisite for targeted treatment and needs-based support. METHODS: In a German metropolitan region, 80 people with suspicion of FASD were assessed from May 2015 to July 2020. The results of this interdisciplinary diagnostic assessment were systematically evaluated and the clinical characteristics of the persons with or without FASD were analysed. RESULTS: Approximately 70% of the population accessing relevant health care was diagnosed with an entity from the FAS spectrum. People with FASD were more likely to have learning disabilities (50 vs. 33%) or intellectual disabilities (40 vs. 10%), while there were no group differences for age and gender. Psychiatric comorbidities, particularly depression (39%) and addiction disorders (31%), were common in both groups. CONCLUSION: As part of a multi-professional standardized diagnosis, FASD clarification is also possible and necessary in adulthood. The diagnostic criteria for FASD should be further evaluated and specified for adults.

[Fetal alcohol spectrum disorders in adults]. / Fetale Alkoholspektrumstörungen bei Erwachsenen.

Fetal alcohol spectrum disorders (FASD) are a common cause of a congenital developmental disability acquired in the womb due to alcohol consumption by the mother during pregnancy. The physical and mental consequences persist into adulthood. The 4­digit code is an evidence-based method for diagnosing the full spectrum of outcomes, i.e. the full picture of fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (pFAS), alcohol-related neurodevelopmental disorder (ARND) and alcohol-related birth defects (ARBD). The four key diagnostic features are (1) growth disorder, (2) facial dysmorphia, (3) central nervous system (CNS) structural and functional abnormalities and (4) prenatal alcohol exposure. Even if the disorder cannot be cured, supportive therapeutic interventions can improve the quality of life and independence and psychiatric comorbidities can be treated.

[Dementia in Adults with Down Syndrome: A Frequent Reason for Admission to Psychiatry]. / Demenz bei Down-Syndrom: Ein häufiger psychiatrischer Vorstellungsgrund.

INTRODUCTION: This study aimed to assess the prevalence and clinical characteristics of dementia in a clinical sample of adults with Down syndrome. Consequences for clinical practice were deduced. METHODS: Patient characteristics and prevalence rates of dementia were evaluated in adults with Down syndrome who were admitted to psychiatry from 2005 to 2012 (N = 75). RESULTS: In every third patient with Down syndrome, dementia was diagnosed in a second assessment 6 to 12 months after initial hospital admission. Patients with dementia were older and more often female, while no association was found with the level of intellectual disability. Thyroid function and calcium values were often abnormal in those with and without dementia. DISCUSSION: In persons with Down syndrome, dementia is a prevalent cause for admission to psychiatry, especially in females and those of advanced age. Services should be adapted to the increased demands.

Digital volume tomography in the diagnosis of peri-implant defects: an in vitro study on native pig mandibles.

BACKGROUND: The aim of this study of native pig mandibles was to investigate the accuracy and quality of the representation of peri-implant defects by intraoral radiography (IR), panoramic radiography (PR), computer tomography (CT), and digital volume tomography (DVT). METHODS: The examination was carried out on 19 native pig mandibles. In the toothless sections of the mandibles, one or two implants were inserted. Following the standardized preparation of peri-implant defects (11 each of dehiscences, fenestrations, and 2- to 3-walled intrabony defects), IR, PR, CT, and DVT were performed. The peri-implant defects were measured using appropriate software on the digitized IR and PR image programs. As a control method, the peri-implant bone defects were measured directly using a reflecting stereomicroscope with measuring ocular. The statistical comparison between the measurements of the radiographic scans and those of the direct readings of the peri-implant defects was performed with Pearson's correlation coefficient. The quality of the radiographic scans was determined through the subjective perception and detectability of the peri-implant defects by five independent observers. RESULTS: In the DVT and CT scans, it was possible to measure all the bone defects in three planes. Comparison with the direct peri-implant defect measurements yielded a mean deviation of 0.17+/-0.11 mm for the DVT scans and 0.18+/-0.12 mm for the CT scans. On the IR and PR images, the defects could be detected only in the mesio-distal and cranio-caudal planes. In comparison with the direct measurements of the peri-implant defects, the IR images revealed a mean deviation of 0.34+/-0.30 mm, and the PR images revealed a mean deviation of 0.41+/-0.35 mm. The quality rating of the radiographic images was highest for the DVT scans. CONCLUSIONS: Overall, the CT and DVT scans displayed only a slight deviation in the extent of the peri-implant defects. Both radiographic imaging techniques permitted imaging of peri-implant defects in three planes, true to scale, and without overlay or distortion. The DVT scans showed the best imaging quality.

Revised Kubelka-Munk theory. I. Theory and application.

Using a statistical analysis of light propagation in media, we propose a revision to Kubelka-Munk (K-M) theory by taking into account the effect of scattering on the path length of light propagation (path variation). This leads to new relationships between the K-M scattering S and absorbing K coefficients and the intrinsic scattering s and absorbing a coefficients of a material that indicate that the S and K coefficients depend non-linearly on both a and s. The additivity law that bridges K-M S and K coefficients of a composite medium, such as dye-dispersed paper (dyed paper) and those of its material components (dye and paper), is also revised. It is further shown that experimental findings on dyed paper that the original K-M theory failed to explain can be clearly understood and accommodated by the new K-M theoretical framework (two-flux approach). Numerical simulations with the revised theory on model ink, paper, and dyed paper have been carried out.

Revised Kubelka-Munk theory. II. Unified framework for homogeneous and inhomogeneous optical media.

We extend the applicability of the recently revised Kubelka-Munk (K-M) theory to inhomogeneous optical media by treating inhomogeneous ink penetration of the substrate. We propose a method for describing light propagation in either homogeneous or inhomogeneous layers using series representations for the K-M scattering and absorption coefficients as well as for intensities of the upward and downward light streams. The conventional and matrix expressions for spectral reflectance and transmittance values of optically homogeneous media in the K-M theory are shown to be special cases of the present framework. Three types of ink distribution-homogeneous, linear, and exponential-have been studied. Simulations of spectral reflectance predict a depression of reflectance peaks and reduction of absorption bands characteristic of hue shifts and significant reduction of saturation and, in turn, color gamut.