bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Sensitivities of Energetic Materials using the Python Language and Libraries
Authors: Mathieu Didier
Published: February 2020

Assessing the value of new compounds as components of energetic materials requires the determination of a significant amount of data, including sensitivities to various stimuli. Unfortunately, the dependence of these properties on molecular structure is still poorly understood. In view of estimating their values for putative high energy molecules, standard quantitative structure‐property relationship (QSPR) methodologies are widely used. In doing so, a special focus is put on standard descriptors and formalisms. To foster further progress through consideration of alternative approaches, this article emphasizes how the Python language and associated libraries make it straightforward to implement arbitrary models, including schemes à la Keshavarz based on the occurrences of highly specific molecular fragments as well as the non‐linear expressions naturally arising from physics‐based approaches to sensitivities. Two previously published models are implemented for illustrative purposes. The first one is a simple fragment‐based equation for electric spark sensitivity of nitroarenes. The second one is a model for impact sensitivity of general molecular energetic materials. In each case a Python implementation is provided as supporting information and may be used as is or serve as a template to implement alternative schemes.
Biochemical analysis of a sugar 4,6‐dehydratase from Acanthamoeba polyphaga Mimivirus
Authors: Ferek Justin D. , Thoden James B. , Holden Hazel M.
Published: February 2020

The exciting discovery of the giant DNA Mimivirus in 2003 challenged the conventional description of viruses in a radical way, and since then, dozens of additional giant viruses have been identified. It has now been demonstrated that the Mimivirus genome encodes for the two enzymes required for the production of the unusual sugar 4‐amino‐4,6‐dideoxy‐d‐glucose, namely a 4,6‐dehydratase and an aminotransferase. In light of our long‐standing interest in the bacterial 4,6‐dehydratases and in unusual sugars in general, we conducted a combined structural and functional analysis of the Mimivirus 4,6‐dehydratase referred to as R141. For this investigation, the three‐dimensional X‐ray structure of R141 was determined to 2.05 Å resolution and refined to an R‐factor of 18.3%. The overall fold of R141 places it into the short‐chain dehydrogenase/reductase (SDR) superfamily of proteins. Whereas its molecular architecture is similar to that observed for the bacterial 4,6‐dehydratases, there are two key regions where the polypeptide chain adopts different conformations. In particular, the conserved tyrosine that has been implicated as a catalytic acid or base in SDR superfamily members is splayed away from the active site by nearly 12 Å, thereby suggesting that a major conformational change must occur upon substrate binding. In addition to the structural analysis, the kinetic parameters for R141 using either dTDP‐d‐glucose or UDP‐d‐glucose as substrates were determined. Contrary to a previous report, R141 demonstrates nearly identical catalytic efficiency with either nucleotide‐linked sugar. The data presented herein represent the first three‐dimensional model for a viral 4,6‐dehydratase and thus expands our understanding of these fascinating enzymes.
Growth and Characterization of Nitrogen‐Polar AlGaN/AlN Heterostructure for High‐Electron‐Mobility Transistor
Authors: Ito Tadatoshi , Sakamoto Ryota , Isono Tatsuya , Yao Yongzhao , Ishikawa Yukari , Okada Narihito , Tadatomo Kazuyuki
Published: February 2020

A nitrogen‐polar (N‐polar) AlGaN/AlN high‐electron‐mobility transistor (HEMT) is proposed, and the generation of a 2D electron gas (2DEG) is simulated. The band diagram of N‐polar (Al)GaN/AlN shows the generation of the 2DEG, whereas that of the conventional metal‐polar (Al)GaN/AlN structure shows the generation of a 2D hole gas. Furthermore, the concentration of the 2DEG is considerably high even when the (Al)GaN layer is as thin as a few nanometers. N‐polar AlGaN/AlN is grown on sapphire substrates with a misorientation angle of 2°; furthermore, atomic force microscope measurements in a range of 5 × 5 μm2 demonstrate that the root‐mean‐square value obtained from atomic force microscopy of N‐polar AlGaN is approximately 0.7 nm. N‐polar AlGaN layers with a thickness of approximately 40–60 nm with more than 50% Al content are almost coherently grown on the N‐polar AlN layer with a thickness of approximately 400 nm.
Improvement of a Terahertz Detector Performance Using the Terajet Effect in a Mesoscale Dielectric Cube: Proof of Concept
Authors: Minin Igor V. , Minin Oleg V. , Delgado-Notario Juan A. , Calvo-Gallego Jaime , Velázquez-Pérez Jesus E. , Ferrando-Bataller Miguel , Meziani Yahya Moubarak
Published: February 2020

Herein, a simple terahertz (THz) receiver that uses subwavelength focusing of the THz beam on the detector area is proposed. As a proof of concept, a THz detection system with an original optical coupling scheme is implemented, where the signal to be detected is coupled to a THz detector through a mesoscale dielectric particle lens. Coherent detection is successfully demonstrated with an enhancement of the detector sensitivity of about 4.3 dB, compared with that of a direct detection system with the slight decreasing (≈1.67 times) of noise equivalent power value. The results show that the proposed method can reduce the size and increase the sensitivity of various THz systems, including imaging, sensing, and ranging, which would enable significant progress in different fields such as physics, medicine, biology, astronomy, security, etc.
Growth and water relations of riparian poplar forests under pressure in Central Asia's Tarim River Basin
Authors: Thomas Frank M. , Lang Petra
Published: February 2020

The riparian forests in the Tarim Basin (NW China) are mainly composed of poplar species (Populus euphratica, Populus pruinosa). In the hyper‐arid climate of this region, the trees are phreatophytes, which rely on access to groundwater. Essential ecosystem services (ESS) of these forests comprise provisioning, regulating, and cultural services. The ESS of the forests are threatened by overuse and a continuous decrease in the groundwater level due to excessive use of water for agriculture, which resulted in a severe reduction of the poplar forest area during the past decades.

Studies revealed that the wood of the forests could be sustainably used through a moderate harvesting intensity. Rejuvenation of the forests from seeds is only possible after sediment deposition and wetting of the soil surface upon flooding and at relatively short distances to the groundwater. At sites with larger groundwater distances, trees can only regenerate vegetatively through root suckers emerging from underground root spacers. With increasing distance from the water table, the stands become older and sparser and, ultimately, are doomed to die off. The research results can contribute to develop suitable management schemes for the conservation and protection of Central Asia's riparian forests. The lower reaches of the Tarim River have been subjected to a water release programme for the past 20 years. We recommend focusing the diversion of such additional (“ecological”) water to stands with a short distance to the groundwater to keep these forests fully functional and to maintain their ability to regenerate from seeds.
An algorithm to compare two‐dimensional footwear outsole images using maximum cliques and speeded‐up robust feature
Authors: Park Soyoung , Carriquiry Alicia
Published: February 2020

Footwear examiners are tasked with comparing an outsole impression (Q) left at a crime scene with an impression (K) from a database or from the suspect's shoe. We propose a method for comparing two shoe outsole impressions that relies on robust features (speeded‐up robust feature; SURF) on each impression and aligns them using a maximum clique (MC). After alignment, an algorithm we denote MC‐COMP is used to extract additional features that are then combined into a univariate similarity score using a random forest (RF). We use a database of shoe outsole impressions that includes images from two models of athletic shoes that were purchased new and then worn by study participants for about 6 months. The shoes share class characteristics such as outsole pattern and size, and thus the comparison is challenging. We find that the RF implemented on SURF outperforms other methods recently proposed in the literature in terms of classification precision. In more realistic scenarios where crime scene impressions may be degraded and smudged, the algorithm we propose—denoted MC‐COMP‐SURF—shows the best classification performance by detecting unique features better than other methods. The algorithm can be implemented with the R‐package shoeprintr.
Effect of SDBS solution on the surface potential properties of the Zhaozhuang coal
Authors: Meng Junqing , Meng Hanxie , Xia Junkai , Niu Jiaxing , Wang Chen
Published: February 2020

It is of great significance to study the effect of surfactants on the coal surface potential for effective dust suppression in mining faces. The effect of different concentrations of sodium dodecyl benzene sulfonate (SDBS) solution on the surface potential of the Zhaozhuang coal was measured by atomic force microscopy (AFM). The experimental results show that the SDBS solution has significant influence on the surface potential of the Zhaozhuang coal. The electrical characteristics of the coal surface at the nanometer scale are different from those of macroscopic or the mesoscopic level. The surface potential of coal is basically a normal distribution, showing certain electrical characteristics. The mean value of the surface potential of the Zhaozhuang coal is increased with the increase in concentration of the SDBS solution; when the concentration of the SDBS solution is 0.3%, the mean value of surface potential is 5.59 mv, which is about two times of the mean value of the surface potential without SDBS solution added. With the increase of the concentration of the SDBS solution, the maximum value of the surface potential of the Zhaozhuang coal increases, and the minimum value decreases. It shows that the SDBS solution has a significant effect on the potential distribution law and the magnitude of the coal surface. Subsequently, on the basis of the constructed Zhaozhuang coal macromolecule model, xtb and Multiwfn simulation software were used to calculate the molecular surface electrostatic potential value and electron density value of the Zhaozhuang coal molecules after adding water molecules. The variation law for the electrostatic potential surface of the molecule was obtained after adding numbers of water molecules to the surface of the coal molecule. The simulation results show that the area proportion of absolute molecular surface electrostatic potential greater than 10 kcal/mol is increased with the growth in the number of water molecules, while the area proportion of absolute molecular surface electrostatic potential less than 10 kcal/mol is decreased. Because of the free state O─H bond polarity of water molecules, the charges on the molecular surface are rearranged in order to change the electron density on the surface of coal molecules, which affects the overall electrostatic potential of the configuration.
Superresilient Hard Carbon Nanofabrics for Sodium‐Ion Batteries
Authors: Ding Chenfeng , Huang Lingbo , Lan Jinle , Yu Yunhua , Zhong Wei‐Hong , Yang Xiaoping
Published: February 2020

Developing supermechanically resilient hard carbon materials that can quickly accommodate sodium ions is highly demanded in fabricating durable anodes for wearable sodium‐ion batteries. Here, an interconnected spiral nanofibrous hard carbon fabric with both remarkable resiliency (e.g., recovery rate as high as 1200 mm s−1) and high Young's modulus is reported. The hard carbon nanofabrics are prepared by spinning and then carbonizing the reaction product of polyacrylonitrile and polar molecules (melamine). The resulting unique hard carbon possesses a highly disordered carbonaceous structure with enlarged interlayer spacing contributed from the strong electrostatic repulsion of dense pyrrolic nitrogen atoms. Its excellent resiliency remains after intercalation/deintercalation of sodium ions. The outstanding sodium‐storage performance of the derived anode includes excellent gravimetric capacity, high‐power capability, and long‐term cyclic stability. More significantly, with a high loading mass, the hard carbon anode displays a high‐power capacity (1.05 mAh cm−2 at 2 A g−1) and excellent cyclic stability. This study provides a unique strategy for the design and fabrication of new hard carbon materials for advanced wearable energy storage systems.
Facilitate Gas Transport through Metal‐Organic Polyhedra Constructed Porous Liquid Membrane
Authors: Deng Zheng , Ying Wen , Gong Ke , Zeng Yu‐Jia , Yan Youguo , Peng Xinsheng
Published: February 2020

Type II porous liquids are demonstrated to be promise porous materials. However, the category of porous hosts is very limited. Here, a porous host metal–organic polyhedra (MOP‐18) is reported to construct type II porous liquids. MOP‐18 is dissolved into 15‐crown‐5 as an individual cage (5 nm). Both the molecular dynamics simulations and experimental gravimetric CO2 solubility test indicate that the inner cavity of MOP‐18 in porous liquids is unoccupied by 15‐crown‐5 and is accessible to CO2. Thus, the prepared porous liquids show enhanced gas solubility. Furthermore, the prepared porous liquid is encapsulated into graphene oxide (GO) nanoslits to form a GO‐supported porous liquid membrane (GO‐SPLM). Owing to the empty cavity of MOP‐18 unit cages in porous liquids that reduces the gas diffusion barrier, GO‐SPLM significantly enhances the permeability of gas.
Comparison of Nonmetallic Inclusion Characteristics in Metal Samples Using 2D and 3D Methods
Authors: Wang Yong , Karasev Andrey , Jönsson Pär G.
Published: February 2020

The characteristics of different shapes of nonmetallic inclusions (NMIs) are determined using different methods. In this respect, various shapes of NMIs, including spherical, octahedral, elongated, bar‐like, plate‐like, polyhedral, and irregular inclusions, are observed in different steels and ferroalloys. The inclusions are investigated using three methods: 1) 2D investigations on a polished cross section (2D method); 2) 3D investigations on a film filter after electrolytic extraction and filtration (EE method); and 3) 3D investigations on a metal surface after electrolytic extraction (MS method). In addition, scanning electron microscopy (SEM) with an energy‐dispersive spectrometer (EDS) is used for the determination of the chemical composition of inclusions. The advantages and limitations of different methods for investigations of different shaped inclusions are discussed. The results show that the 2D method is less precise to detect the morphology, size, and number of inclusions; however, the EE and MS methods are used to determine a more accurate morphology. Furthermore, the MS method is found to be more advantageous in detecting large‐sized inclusions. This study also shows that the results on both the film filter and metal surface should be grouped together to obtain more comprehensive information of the inclusion characteristics.
Cell immaturity and white/beige adipocyte potential of primary human adipose-derived stromal cells are restrained by culture-medium TGFβ1
Authors: Leménager Hélène , Fiévet Loïc M. A. , Guilloton Fabien , Naji Abderrahim , Descamps Jean-Gérard , Chaput Benoît , Suganuma Narufumi , Pagès Jean-Christophe , Sensebé Luc , Carrière Audrey , Casteilla Louis , Deschaseaux Frédéric
Published: February 2020

Human adipose-derived stem/stromal cells (hASCs) can differentiate into specialized cell types and thereby contribute to tissue regeneration. As such, hASCs have drawn increasing attention in cell therapy and regenerative medicine, not to mention the ease to isolate them from donors. Culture conditions are critical for expanding hASCs while maintaining optimal therapeutic capabilities. Here, we identified a role for transforming growth factor β1 (TGFβ1) in culture medium in influencing the fate of hASCs during in vitro cell expansion. Human ASCs obtained after expansion in standard culture medium (Standard-hASCs) and in endothelial cell growth medium 2 (EGM2-hASCs) were characterized by high-throughput transcriptional studies, gene set enrichment analysis and functional properties. EGM2-hASCs exhibited enhanced multipotency capabilities and an immature phenotype compared with Standard-hASCs. Moreover, the adipogenic potential of EGM2-hASCs was enhanced, including toward beige adipogenesis, compared with Standard-hASCs. In these conditions, TGFβ1 acts as a critical factor affecting the immaturity and multipotency of Standard-hASCs, as suggested by small mother of decapentaplegic homolog 3 (SMAD3) nuclear localization and phosphorylation in Standard-hASCs vs EGM2-hASCs. Finally, the typical priming of Standard-hASCs into osteoblast, chondroblast, and vascular smooth muscle cell (VSMC) lineages was counteracted by pharmacological inhibition of the TGFβ1 receptor, which allowed retention of SMAD3 into the cytoplasm and a decrease in expression of osteoblast and VSMC lineage markers. Overall, the TGFβ1 pathway appears critical in influencing the commitment of hASCs toward osteoblast, chondroblast, and VSMC lineages, thus reducing their adipogenic potential. These effects can be counteracted by using EGM2 culture medium or chemical inhibition of the TGFβ1 pathway.
An integrated damping system for tall buildings
Authors: Martinez‐Paneda Miguel , Elghazouli Ahmed Y.
Published: February 2020

This paper proposes an integrated damping system that aims at providing relatively high damping levels through the mobilization of a proportion of the structure's own mass. This offers significantly higher mass levels and, consequently, considerably more damping compared to conventional tuned mass dampers. Fluid viscous dampers are used to control accelerations in parallel with springs to resist the static loads applied to the moving mass. The advantages of employing relatively large mass levels in achieving considerable damping and reducing sensitivity to tuning are first analyzed using an idealized two degree of freedom structural representation. This is then followed by a description of the proposed “integrated damping system,” which is illustrated through a case study of a 250‐m tall building. The benefits of the proposed damping system are demonstrated through several numerical parametric assessments, as well as a selected suite of earthquake records. For the adopted case study, it is shown that, besides reducing the level of perceivable accelerations, the use of the suggested arrangement can offer an equivalent damping exceeding 50% of the critical damping, resulting in more than 40% reduction in the wind loads as well as over 60% reduction in displacement and acceleration response under seismic excitations.
From boundary data to bound states. Part II. Scattering angle to dynamical invariants (with twist)
Authors: Kälin Gregor , Porto Rafael A.
Published: February 2020

Abstract

We recently introduced in [9] aboundary-to-bounddictionary between gravitational scattering data and observables for bound states of non-spinning bodies. In this paper, we elaborate further on thisholographicmap. We start by deriving the following — remarkably simple — formula relating the periastron advance to the scattering angle:$$ \Delta \Phi \left(J,\mathcal{E}\right)=\upchi \left(J,\mathcal{E}\right)+\upchi \left(-J,\mathcal{E}\right) $$ΔΦJE=χJE+χ−JE, via analytic continuation in angular momentum and binding energy. Using explicit expressions from [9], we confirm its validity to all orders in the Post-Minkowskian (PM) expansion. Furthermore, we reconstruct the radial action for the bound state directly from the knowledge of the scattering angle. The radial action enables us to write compact expressions for dynamical invariants in terms of the deflection angle to all PM orders, which can also be written as a function of the PM-expanded amplitude. As an example, we reproduce our result in [9] for the periastron advance, and compute the radial and azimuthal frequencies and redshift variable to two-loops. Agreement is found in the overlap between PM and Post-Newtonian (PN) schemes. Last but not least, we initiate the study of our dictionary including spin. We demonstrate that the same relation between deflection angle and periastron advance applies for aligned-spin contributions, withJthe (canonical)totalangular momentum. Explicit checks are performed to display perfect agreement using state-of-the-art PN results in the literature. Using the map between test- and two-body dynamics, we also compute the periastron advance up to quadratic order in spin, to one-loop and to all orders in velocity. We conclude with a discussion on the generalized ‘impetus formula’ for spinning bodies and black holes as ‘elementary particles’. Our findings here and in [9] imply that the deflection angle already encodes vast amount of physical information for bound orbits, encouraging independent derivations using numerical and/or self-force methodologies.
Stepwise development and model checking of adistributed interlocking system using RAISE
Authors: Geisler S. , Haxthausen A. E.
Published: February 2020

This paper considers the challenge of designing and verifying control protocols for geographically distributed railway interlocking systems. It describes how this challenge can be tackled by stepwise development and model checking of state transition system models in a new extension of the RAISE Specification Language.

Railway interlocking systems are reconfigurable systems which can be configured by supplying data describing the network to be controlled and other details. Therefore, such systems are natural candidates for being modelled by generic state transition systems, which abstract away from the concrete configuration at the time of modelling, and can later be instantiated with concrete data.

For a real-world case study, a generic state transition system is developed in steps, starting with an abstract model of the essential system behaviour and incrementally adding details and restrictions. The stepwise development method allows different variants of the control protocol to be explored. The generic models are instantiated with concrete configuration data, after which desired properties, in particular safety properties, of the system models are verified using model checking.
Effective Behaviour of Critical-Contrast PDEs: Micro-resonances, Frequency Conversion, and Time Dispersive Properties. I
Authors: Cherednichenko Kirill D. , Ershova Yulia Yu. , Kiselev Alexander V.
Published: February 2020

A novel approach to critical-contrast homogenisation for periodic PDEs is proposed, via an explicit asymptotic analysis of Dirichlet-to-Neumann operators. Norm-resolvent asymptotics for non-uniformly elliptic problems with highly oscillating coefficients are explicitly constructed. An essential feature of the new technique is that it relates homogenisation limits to a class of time-dispersive media.
Post-contrast acute kidney injury in a hospitalized population: short-, mid-, and long-term outcome and risk factors for adverse events
Authors: Cheng Wei , Wu Xi , Liu Qian , Wang Hong-Shen , Zhang Ning-Ya , Xiao Ye-Qing , Yan Ping , Li Xu-Wei , Duan Xiang-Jie , Peng Jing-Cheng , Feng Song , Duan Shao-Bin
Published: February 2020

Objectives

To investigate the prognosis including major adverse kidney events within 30 days (MAKE30) and 90-day and 1-year adverse outcome in hospitalized patients with post-contrast acute kidney injury (PC-AKI) to identify high-risk factors.

Methods

This retrospective observational study included 288 PC-AKI patients selected from 277,898 patients admitted to hospitals from January 2015 to December 2015. PC-AKI was defined according to the 2018 guideline of European Society of Urogenital Radiology. Multivariable Cox regression and logistic regression analyses were used to analyze main outcome and risk factors.

Results

PC-AKI patients with AKI stage ≥ 2 had much higher incidence of MAKE30 than those with AKI stage 1 (RR = 7.027, 95% CI 4.918–10.039). Persistent renal dysfunction, heart failure, central nervous system failure, baseline eGFR < 60 mL/min/1.73 m2, oliguria or anuria, blood urea nitrogen ≥ 7.14 mmol/L, respiratory failure, and shock were independent risk factors of 90-day or 1-year adverse prognosis (p < 0.05). Compared with transient renal dysfunction, PC-AKI patients with persistent renal dysfunction had a higher all-cause mortality rate (RR = 3.768, 95% CI 1.612–8.810; RR = 4.106, 95% CI 1.765–9.551) as well as combined endpoints of death, chronic kidney disease, or end-stage renal disease (OR = 3.685, 95% CI 1.628–8.340; OR = 5.209, 95% CI 1.730–15.681) within 90 days or 1 year.

Conclusions

PC-AKI is not always a transient, benign creatininopathy, but can result in adverse outcome. AKI stage is independently correlated to MAKE30 and persistent renal dysfunction may exaggerate the risk of long-term adverse events.

Key Points

• PC-AKI can result in adverse outcome such as persistent renal dysfunction, dialysis, chronic kidney disease (CKD), end-stage renal disease (ESRD), or death.

• AKI stage is independently correlated to MAKE30.

• Persistent renal dysfunction may exaggerate the risk of long-term adverse events.
Hepatocellular adenomas: is there additional value in using Gd-EOB-enhanced MRI for subtype differentiation?
Authors: Auer Timo Alexander , Fehrenbach Uli , Grieser Christian , Penzkofer Tobias , Geisel Dominik , Schmelzle Moritz , Müller Tobias , Bläker Hendrik , Seehofer Daniel , Denecke Timm
Published: February 2020

Purpose

To differentiate subtypes of hepatocellular adenoma (HCA) based on enhancement characteristics in gadoxetic acid (Gd-EOB) magnetic resonance imaging (MRI).

Materials and methods

Forty-eight patients with 79 histopathologically proven HCAs who underwent Gd-EOB-enhanced MRI were enrolled (standard of reference: surgical resection). Two blinded radiologists performed quantitative measurements (lesion-to-liver enhancement) and evaluated qualitative imaging features. Inter-reader variability was tested. Advanced texture analysis was used to evaluate lesion heterogeneity three-dimensionally.

Results

Overall, there were 19 (24%) hepatocyte nuclear factor (HNF)-1a-mutated (HHCAs), 37 (47%) inflammatory (IHCAs), 5 (6.5%) b-catenin-activated (bHCA), and 18 (22.5%) unclassified (UHCAs) adenomas. In the hepatobiliary phase (HBP), 49.5% (39/79) of all adenomas were rated as hypointense and 50.5% (40/79) as significantly enhancing (defined as > 25% intralesional GD-EOB uptake). 82.5% (33/40) of significantly enhancing adenomas were IHCAs, while only 4% (1/40) were in the HHCA subgroup (p < 0.001). When Gd-EOB uptake behavior was considered in conjunction with established MRI features (binary regression model), the area under the curve (AUC) increased from 0.785 to 0.953 for differentiation of IHCA (atoll sign + hyperintensity), from 0.859 to 0.903 for bHCA (scar + hyperintensity), and from 0.899 to 0.957 for HHCA (steatosis + hypointensity). Three-dimensional region of interest (3D ROI) analysis showed significantly increased voxel heterogeneity for IHCAs (p = 0.038).

Conclusion

Gd-EOB MRI is of added value for subtype differentiation of HCAs and reliably identifies the typical heterogeneous HBP uptake of IHCAs. Diagnostic accuracy can be improved significantly by the combined analysis of established morphologic MR appearances and intralesional Gd-EOB uptake.

Key Points

•Gd-EOB-enhanced MRI is of added value for subtype differentiation of HCA.

•IHCA and HHCA can be identified reliably based on their typical Gd-EOB uptake patterns, and accuracy increases significantly when additionally taking established MR appearances into account.

•The small numbers of bHCAs and UHCAs remain the source of diagnostic uncertainty.
PIV-based pressure estimation in the canopy of urban-like roughness
Authors: Ferreira M. Aguiar , Ganapathisubramani B.
Published: February 2020

In-plane velocity measurements from PIV are used to estimate the pressure field above and within the canopy of two staggered arrays of cuboids, with distinct height distributions, via 2D-RANS and 2D-TH. The viability of this approach is examined by first comparing the mean drag profiles against reported wind-tunnel measurements that were carried out under similar test conditions and numerical simulations (LES and DNS). The surface drag is extrapolated from the nearest data point surrounding the roughness elements. Second, estimates of the friction velocity $$U_{\tau }^p$$Uτp and the zero-plane displacement height $$d^p$$dp are obtained by integrating the axial pressure difference across each individual obstacle, assuming it is spanwise uniform. These are compared against direct measurements of the wall-shear stress from a floating-element balance and a pressure-tapped cube, as well as against estimates from indirect methods. In addition to mean pressure maps, snapshots of the pressure field are obtained via 2D-TH, based on Taylor’s Hypothesis, which are used to compute the RMS of the pressure fluctuations on the surface of a cube. The results indicate that 2D-RANS and 2D-TH perform adequately, providing reasonable estimates of the mean pressure distribution and of the boundary-layer flow parameters, outperforming indirect methods which rely on equilibrium assumptions that are often not verified.

Graphic abstract
Non-localised contact between beams with
circular and elliptical cross-sections
Authors: Magliulo Marco , Lengiewicz Jakub , Zilian Andreas , Beex Lars A. A.
Published: February 2020

The key novelty of this contribution is a dedicated technique to
efficiently determine the distance (gap) function between parallel or almost parallel
beams with circular and elliptical cross-sections. The technique consists of
parametrizing the surfaces of the two beams in contact, fixing a point on the centroid
line of one of the beams and searching for a constrained minimum distance between the
surfaces (two variants are investigated). The resulting unilateral (frictionless)
contact condition is then enforced with the Penalty method, which introduces compliance
to the, otherwise rigid, beams’ cross-sections. Two contact integration schemes are
considered: the conventional slave-master approach (which is biased as the contact
virtual work is only integrated over the slave surface) and the so-called two-half-pass
approach (which is unbiased as the contact virtual work is integrated over the two
contacting surfaces). Details of the finite element formulation, which is suitably
implemented using Automatic Differentiation techniques, are presented. A set of
numerical experiments shows the overall performance of the framework and allows a
quantitative comparison of the investigated variants.
The impact of the verbal instruction and task characteristics on effect-based action control
Authors: Vogel Diana , Rudolf Matthias , Scherbaum Stefan
Published: February 2020

According to ideomotor theory, when people perform a movement and observe its subsequent effect, they acquire a bidirectional action-effect association. If at a later point they want to produce the effect, its anticipation activates and allows executing the corresponding action. In ideomotor induction tasks, several task characteristics determine whether participants use the experimentally induced action-effect associations to pre-activate the corresponding actions. Here, we assess the impact of the verbal instruction, the task relevance of the effect stimuli and the presentation of post-response effects on the expression of action-effect associations. The results show that an instruction stressing the stimulus–effect correspondence prompts participants to utilize the presented effects more than an instruction stressing the stimulus-response correspondence. Furthermore, the induced action-effect associations were only expressed when the effects were relevant for the task and when post-response effects were presented in the test phase. These findings show the importance of the particular task construction for the expression of the experimentally manipulated action-effect knowledge.
Examining the Relationship Between Autism Traits and Sleep Duration as Predictors of Suicidality
Authors: Hochard K. D. , Pendrous R. , Mari T. , Flynn S.
Published: February 2020

Short sleep duration is a known risk factor for suicidality in the general population, yet it is unclear how short sleep interacts with autism traits in predicting suicidality. In this cross-sectional online study, a general population sample (N = 650) completed measures assessing autism traits, suicidal ideation, and sleep duration. Moderated hierarchical regressions demonstrated that higher autism traits and shorter sleep were independent predictors of increased suicide ideation. However, sleep duration did not significantly moderate the autism trait to suicide ideation relationship. Future work should explore this relationship longitudinally using objective measures before considering intervention work to increase sleep duration in those with elevated autism traits.
Growing a small firm; experiences and managing difficult processes
Authors: Tunberg Maria , Anderson Alistair R.
Published: February 2020

Contrary to a simple model of small firm growth where increased inputs produce greater outputs, we consider growth is a complex and difficult process. Accordingly, the paper is concerned with how small firms grow, especially how they make sense of the growth process. We collected narratives of the experiences of small firm growth in an extended case study to draw out how growth is understood and managed. We saw how owners became entangled in the process of growing, especially where a change in one aspect led to problems in other dimensions of growth. Their narratives were about trying to make sense, and give some sense to the complexity of growth and some direction to what they should manage. We identified a repertoire of narrative forms: Growth is understood through output indicators, growth is treated as the internal development of the firm and finally, growth is taken to be inevitable - a necessity to which the firm has to conform. These illustrate how growth can be understood as processes of growing, bound up in the context, created in space and time, and contingent on how growth is understood and experienced. Far from a smooth trajectory, enacting growth reflects the experience of the moment, it is shaped by reactions rather than strategy and it is messy rather than ordered. This study contributes to the literature by complementing the functionalist and output oriented view by understanding firm growth as a social phenomenon constructed and reconstructed in the interactions between people and experiences of context.
Analyzing prospective mathematics teachers’ diagnostic processes in a simulated environment
Authors: Wildgans-Lang Angelika , Scheuerer Sarah , Obersteiner Andreas , Fischer Frank , Reiss Kristina
Published: February 2020

Diagnostic competences are an essential facet of teacher competence. Many studies have investigated the quality of teachers’ judgments of students’ competences. However, little is known about the processes that lead to these judgments and about the ways to promote these processes in the early phase of teacher training. The aim of the research project on which we report in this paper was to develop a simulated computer-based environment that allows assessing and promoting the diagnostic processes of prospective teachers. In the simulated environment, ‘virtual third-graders’ solve mathematical problems. Participants are asked to diagnose the students’ competence levels according to a theoretical model, which has been empirically validated. Participants can repeatedly select mathematical problems of varying difficulty levels, assign them to a virtual student, and then receive the student’s written solution. In this paper, we present the conceptualization of the simulated environment. We also report on the results of a pilot study with 91 prospective primary school mathematics teachers to analyze whether the environment allows an assessment of individual differences in diagnostic processes. The majority of participants rated the environment as authentic and as one in which they could become immersed. Overall, participants were fairly accurate in their diagnoses concerning the student’s competence level. However, log data and participants’ written notes indicated that there was large variability in their diagnostic processes. Participants varied greatly in the number of mathematical problems they assigned to a student during their diagnostic process, and in how strongly the difficulty of these problems deviated from the student’s true competence level. Overall, the data suggest that the simulated environment has the potential to assess diagnostic processes in a valid way. We discuss open questions and issues for further development.
Qualities of mathematical discourses in kindergartens
Authors: Hundeland Per Sigurd , Carlsen Martin , Erfjord Ingvald
Published: February 2020

In this study we investigated qualities of the mathematical discourse in four kindergarten classes in which kindergarten teachers and 5-year-old children engaged in mathematical learning activities. We analysed differences in the mathematical discourses in two experimental kindergarten classes and two control kindergarten classes, in a research and development project. The overarching research question guiding our study was as follows: what characterises the mathematical discourse unfolding in kindergarten classes? In our study we drew on the theoretical framework Mathematical Discourse in Instruction coined by Adler and Ronda, as we quantified the collected qualitative data. Our analyses identified significant characteristics of mathematical discourse with respect to the children’s opportunities to contribute with ideas and arguments. The discourse in the kindergartens differed both with respect to the extent and nature of verbal utterances among the participants, as well as the mathematical engagement nurtured amongst the children. Moreover, the mathematical discourse within the experimental kindergarten classes, to a greater extent than that in the control kindergarten classes, initiated opportunities for the participating children’s mathematical learning.
Krankheitsbedingte Fehlzeiten des Pflegepersonals eines Maximalversorgers – Analyse und Handlungsanweisungen
Authors: Röper Johann , Fleßa Steffen
Published: February 2020

Hintergrund

Krankheitsbedingte Fehlzeiten stellen im gesundheitsbetrieblichen Leistungserstellungsprozess Produktivitätsminderungen dar. Angesichts knapper Pflegefachkräfte, des demografischen Wandels und der Veränderung des Krankheitspanoramas sind die Kenntnis und das Management von Ausfällen in der betrieblichen Zielkonzeption zu verankern, um die Leistungsbereitschaft sicherzustellen. Für die systematische Einordnung möglicher Ausfallursachen und Ableitung von Maßnahmen zur Vermeidung von Produktivitätsverlusten wird ein auf die Krankenpflege ausgerichtetes Modell entwickelt und vorgestellt. Dieses soll die Analyse von Fehlzeitendaten der Pflegekräfte eines maximalversorgenden Krankenhauses strukturieren.

Ziel

Ziele dieser Studie sind die Entwicklung eines Analysemodells für Fehlzeiten von Pflegepersonal in Krankenhäusern und dessen Anwendung auf Fehlzeitendaten eines maximalversorgenden Krankenhauses. Mithilfe des Modells sollen die Ursachen für Fehlzeiten systematisch erfasst, strukturiert und schließlich analysiert werden. Aus den Analyseergebnissen sollen schließlich Ansatzpunkte, wie sich Fehlzeiten betrieblich steuern lassen könnten, abgeleitet werden.

Methodik

Zur Analyse von Fehlzeiten im Pflegeberuf wird ein systematischer Ordnungsrahmen entwickelt. Die Anwendung der Analysemethode erfolgt am Beispiel eines deutschen maximalversorgenden Krankenhauses, das Daten zur wissenschaftlichen Auswertung zur Verfügung stellte. Im Betrachtungszeitraum von 2 Jahren wurde ein Datensatz von 73.996 registrierten Ausfällen von rund 1500 Pflegekräften explorativ analysiert.

Ergebnisse

Das Modell zur Analyse von Fehlzeiten beweist seine Anwendbarkeit für die Strukturierung und die systematische Erfassung von Ausfallursachen. Der erarbeitete Denkrahmen liefert damit sowohl einen wissenschaftlichen als auch praktischen Beitrag und kann in weiteren Fehlzeitenanalysen Anwendung finden. Als wichtiger Ansatzpunkt zur Reduktion der Fehlzeiten am Erfahrungsobjekt erweist sich die Homogenisierung der Personalstruktur, die an den Organisationeinheiten ansetzen sollte. Diese kann z. B. über den Altersdurchschnitt gesteuert werden, da den Ergebnissen zufolge ältere Pflegekräfte im Durchschnitt deutlich höhere krankheitsbedingte Fehlzeiten verursachen als junge. Männliche Pflegekräfte fehlten indes krankheitsbedingt öfter als weibliche. Darüber hinaus sollte anhand von Mitarbeitergesprächen regelmäßig der Kontakt zur Belegschaft gesucht werden, um motivationsbedingte Fehlzeiten zu verhindern und frühzeitig Kenntnis über etwaige Probleme zu erlangen.

Fazit

Die erarbeitete Analysemethode ermöglicht die systematische Erfassung und Untersuchung von Fehlzeiten. Eine Reduktion der Fehlzeiten ist möglich. Sie erfordert die konsequente Umsetzung von Maßnahmen, die sich in der betrieblichen Zielkonzeption wiederfinden müssen.
Herausforderungen und Entwicklungsperspektiven des Steuersystems
Authors: Niemann Rainer , Schreiber Ulrich
Published: February 2020

Wir gehen von den großen ökonomischen und gesellschaftlichen Herausforderungen Digitalisierung, ökonomische Ungleichheit und Klimawandel aus und untersuchen daraus resultierende Entwicklungsperspektiven für die Steuersysteme Deutschlands und Österreichs. Die Digitalisierung erschwert die Besteuerung wegen abnehmender physischer Präsenz und zunehmender internationaler Mobilität der Steuerbasen. Da Arbeitseinkommen international wenig mobil sind, werden Steuern auf Arbeitseinkommen ein wesentlicher Bestandteil der beiden Steuersysteme bleiben. Auch die Umsatzsteuer, die den international kaum mobilen lokalen Konsum trifft, wird ihre Bedeutung behalten. Dagegen werden Steuern, welche international mobile Unternehmensgewinne treffen, an Bedeutung verlieren, solange der Steuerwettbewerb nicht wirksam durch internationale Kooperation eingedämmt wird. Die Besteuerung der Gewinne sollte deshalb stärker auf die weitgehend immobilen, letztbegünstigten natürlichen Personen ausgerichtet sein. Zur steuerlichen Korrektur ökonomischer Ungleichheit ist die Vermögensteuer vor allem wegen der internationalen Ausweichmöglichkeiten und der hohen Erhebungs- und Befolgungskosten wenig geeignet. Hier bietet sich eher die Erbschaft- und Schenkungsteuer an; die Verschonung von Unternehmensvermögen ist damit aber nicht zu vereinbaren. Sofern die Besteuerung dem Klimaschutz dienen soll, ist eine einheitliche globale Steuer auf CO2erforderlich, deren Höhe sich nach der zu erreichenden Emissionsminderung richtet. Da es auf kurze und mittlere Sicht schwer ist, Umweltsteuern auszuweichen, sind deren Verteilungswirkungen zu beachten.
Vitamin D and Haematopoiesis
Authors: Brown Geoffrey , Kutner Andrzej , Marcinkowska Ewa
Published: February 2020

Purpose of Review

This review examines the influences of active vitamin D on ‘developmental’ haematopoiesis and the immune cells produced. Haematopoiesis gives rise to the platelets, erythrocytes and a wide range of immune cell types each of which performs a specific role to protect the organism from a myriad of infectious agents. The newly produced immune cells, for example, monocytes, dendritic cells and T and B lymphocytes, are activated in response to the presence of an infectious agent and differentiate further to perform their roles.

Recent Findings

Binding of 1α,25-dihydroxyvitamin D3, the most active metabolite of vitamin D3, to its receptor, the vitamin D receptor, regulates the expression of very many different genes and therefore a mode(s) of action of vitamin D relates to the regulation of expression of cell-specific genes. The haematopoietic cytokines are essential regulators of haematopoiesis and the further maturation and functionality of the immune cell types. We now know that some cytokines also instruct the development of a particular type of blood cell.

Vitamin D influences the ‘early’ development of monocytes and invariant natural killer T cells and the further maturation of some immune cell types. Findings regarding the regulation of gene expression have revealed that there are links between the actions of vitamin D and cytokines. Whilst we do not have as yet an entirely clear picture on this matter, there are benefits to ‘health’ of the immune system from vitamin D supplementation.
Peridynamic Modelling of Fracture in Polycrystalline Ice
Authors: Lu Wei , Li Mingyang , Vazic Bozo , Oterkus Selda , Oterkus Erkan , Wang Qing
Published: February 2020

In this study, a peridynamic material model for a polycrystalline ice is utilised to investigate its fracture behaviour under dynamic loading condition. First, the material model was validated by considering a single grain, double grains and polycrystalline structure under tension loading condition. Peridynamic results are compared against finite element analysis results without allowing failure. After validating the material model, dynamic analysis of a polycrystalline ice material with two pre-existing cracks under tension loading is performed by considering weak and strong grain boundaries with respect to grain interiors. Numerical results show that the effect of microstructure is significant for weak grain boundaries. On the other hand, for strong grain boundaries, the effect of microstructure is insignificant. The evaluated results have demonstrated that peridynamics can be a very good alternative numerical tool for fracture analysis of polycrystalline ice material.
A sediment-mixing process model of till genesis, using texture and clay mineralogy data from Saginaw lobe (Michigan, USA) tills
Authors: Schaetzl Randall J. , Baish Christopher , Colgan Patrick M. , Knauff Jarrod , Bilintoh Thomas , Wanyama Dan , Church Michelle , McKeehan Kevin , Fulton Albert , Arbogast Alan F.
Published: February 2020

We present a sediment-mixing process model of till genesis based on data from surface tills of the Saginaw lobe terrain in lower Michigan. Our research uses a spatial approach to understanding glacial landsystems and till genesis. We sampled calcareous till at 336 upland sites and at 17 sites in lacustrine sediment of the Saginaw Lake plain. The loamy tills have bimodal grain-size curves, with a fine-texture mode near the silt–clay boundary and a sand mode. Spatial grouping analysis suggests that tills can be divided into six groups, each with different textures and clay mineral compositions that vary systematically down-ice. The similarity among groups with respect to the silt–clay mode and clay mineralogy argues for a common origin for the fines—illite-rich lacustrine sediment of the Saginaw Lake plain. Fine-textured sediments were probably entrained, transported, and deposited down-ice as till, which also becomes sandier and enriched in kaolinite, reflecting increasing mixing with shallow sandstone bedrock with distance from the lacustrine clay source. Clayey tills on the flanks of the Saginaw terrain may reflect proglacial ponding against nearby uplands. A process model of progressive down-ice mixing of preexisting fine lake sediments with crushed/abraded sandstone bedrock helps to better explain till textures compared with a purely crushing/abrasion process model.