bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal Structure and the Spectral Response of the Ba‐Doped SrTiO3 Incipient Ferroelectrics
Authors: Linnik Ekaterina D. , Lukyanchuk Igor A. , Mikheykin Alexey S. , Ragulya Andrey V. , Gorshunov Boris P. , Alyabyeva Liudmila N. , Zhukov Sergey S. , Mezzane Daoud , Razumnaya Anna G.
Published: April 2021

The crystal structure and lattice dynamics of quantum paraelectric BaxSr1−xTiO3 (x = 0, 0.01, 0.02) solid solutions are studied using X‐ray diffraction (XRD), Raman and terahertz‐infrared (THz‐IR) spectroscopies in a temperature range of 4–300 K. XRD and Raman spectroscopy reveal the cubic‐to‐tetragonal nonpolar structural phase transition at about 100 K. At the same time, Raman spectra manifest the presence of polar modes, TO2 and TO4, normally prohibited in paraelectric phase. Emergence of these modes indicates the appearance of the polar nanoregions in a broad temperature range. The modes become more intensive at low temperatures, and temperature dependence of their intensities on cooling reveals the kink‐like change of the slope from flat to steep, indicating on activation of polar nanoregions. The transmission THz‐IR spectra show that squared frequency of the polar TO1 soft mode, responsible for ferroelectric transition, follows Cochran's behavior at high temperatures. However, at low temperatures, it doesn't vanish at extrapolated Curie temperature but saturates, demonstrating the plateau feature below 20 K. This behavior, coherent with known saturation of the dielectric constant, indicates that transition to ferroelectric phase in BaxSr1−xTiO3 is suppressed by quantum fluctuations and the system stays in quantum paraelectric state at very low temperatures.
Single‐State Crystal Field Parametrization in the Cubic Symmetry Systems
Authors: Mulak Maciej , Mulak Jacek
Published: April 2021

A single‐state algebraic parametrization is applied to 47 free‐ion triply ionized lanthanide electronic states that originate from 11 ions embedded in four various octahedral hosts, mainly in Cs2NaLaCl6 matrix. The obtained single‐state parametrizations averaged over the considered |J⟩ states of 2J + 1 degeneracy adequately reproduce the conventional fitting parametrization, where as many pairs of the cubic B
40 and B
60 crystal field (CF) parameters as the states in the configuration are replaced by only one universal pair. This is the essence of the fitting procedure. The comparison between the single‐state parametrizations and the corresponding fitted parametrization reveals the structure of anatomy of the fitting as well as the component states of the configuration giving an untypical contribution to the mean value. The single‐state parametrization unveils directly not only the physical CF parameters of the state but also the host ligand strength, it means its position in the spectrochemical series.
Multipartite Nonlocality of Finite and Infinite Transverse‐Field Ising Model
Authors: Liu Yanhong , Bao Jia , Guo Bin , Sun Zhaoyu
Published: April 2021

The multipartite nonlocality of finite and infinite transverse‐field Ising model is investigated. For the finite chain, the exact diagonalization method is used to study the multipartite nonlocality at zero and finite temperatures. It is found that the logarithm of nonlocality S presents the linear relationship with the chain length of N at zero temperature. The multipartite nonlocality S shows a peak value near the phase transition point, which can be used to characterize the quantum phase transition of the Ising model. The inherent physical mechanics is that the nonlocality S captures the effect of low‐lying states with a small energy gap. The nonlocality S at the finite temperature is also observed to be scaled as log2
S ≈ aN + b at any fixed magnetic field B, where a and b are fitting parameters. For the infinite chain, the thermal tensor network algorithm is used to examine the multipartite nonlocality. The behaviors of nonlocality S of the infinite chain at the finite temperature are similar to those of finite chain. Compared with the finite chain, the positions of the peak values of the multipartite nonlocality shift to the larger magnetic field, and the peak values are smaller than those of finite chain.
Recent Progress on Aluminum Gallium Nitride Deep Ultraviolet Lasers by Molecular Beam Epitaxy
Authors: Zhang Qihua , Yin Xue , Zhao Songrui
Published: April 2021

Over the past decades, the aluminum gallium nitride (AlGaN) alloy system has received wide interest for the development of semiconductor deep ultraviolet (DUV) lasers due to its direct, tunable, and ultrawide bandgap energies (3.4–6.2 eV). The progress, nonetheless, has been remained slow, which is ascribed to a few major challenges, including large dislocation and defect densities, difficulty in obtaining p‐type high‐Al‐content AlGaN layers with a sufficient p‐type conduction, the large electric polarization fields, and the unfavorable optical polarization. In recent years, with AlGaN alloys grown by molecular beam epitaxy (MBE), including both thin films and nanowire structures, remarkable advancements have been made, such as highly conductive p‐type high‐Al‐content AlGaN epilayers with resistivities as low as 0.7 Ω cm and DUV lasing down to 239 nm with nanowire structures under a direct current injection. Herein, the recent progress on the DUV lasers by the MBE‐grown AlGaN is reviewed. The challenges and prospects of the MBE‐grown AlGaN for DUV lasers are also discussed.
Event‐driven disturbance rejection control for discrete time‐varying systems
Authors: Zhang Jinhui , Yin Jianfang , Xu Hao , Sun Zhongqi
Published: April 2021

In this article, the problem of event‐driven output feedback control is addressed for discrete time‐varying systems with external disturbances. To estimate the unmeasured system states and external disturbances, a novel time‐varying extended state functional observer is designed. Then, an event‐driven control scheme is proposed to reduce the utilization of the communication resources, and the optimal feedback gain is designed by minimizing the upper bound of the cost function. Moreover, the disturbance rejection analyses are performed. Finally, the effectiveness of the proposed control approaches is illustrated through the numerical simulations.
Promotion time cure rate model with a neural network estimated nonparametric component
Authors: Xie Yujing , Yu Zhangsheng
Published: April 2021

Promotion time cure rate models (PCM) are often used to model the survival data with a cure fraction. Medical images or biomarkers derived from medical images can be the key predictors in survival models. However, incorporating images in the PCM is challenging using traditional nonparametric methods such as splines. We propose to use neural network to model the nonparametric or unstructured predictors' effect in the PCM context. Expectation‐maximization algorithm with neural network for the M‐step is used for parameter estimation. Asymptotic properties of the proposed estimates are derived. Simulation studies show good performance in terms of both prediction and estimation. We finally apply our methods to analyze the brain images from open access series of imaging studies data.
Multitarget Diallyl Disulfides (DADS) against Aβ Aggregation: Screening through Molecular Docking with Aβ42 & ZnII‐Aβ16, ADME, DFT & Synthetic Strategy
Authors: Singhal Sugandha , Khanna Pankaj , Misra Neeti , Khanna Leena
Published: April 2021

The Aβ42 amyloid aggregation and its stabilization by coordination metals like ZnII through chelation, are the major pathological causes behind the occurrence of Alzheimer's disease (AD). Natural compounds like curcumin and chrysamine G have depicted Aβ42 aggregation inhibition, metal chelation and anti‐oxidant properties. Likewise garlic derived diallyl disulfide (DADS) has shown metal chelation, acetylcholinesterase (AChE) inhibition and antioxidant properties. In the present study a library of thirty four unnatural symmetrical DADS derivatives with aliphatic, aryl and new heteroaryl spacer groups, has been designed on the basis of electron releasing/withdrawing substituents and N/O heteroatom. The library was screened using various theoretical tools for their molecular properties and bioactivity with different receptors, to filter eleven potentially active derivatives. Further, Molecular docking study with Aβ42 (PDB ID: 1IYT) and ZnII‐Aβ16 (PDB ID: 1ZE9) displayed significant binding of heteroaryl DADS derivatives with highest binding energies and zinc binding ability. DFT calculations helped to predict their binding ability with free ZnII ion through disulfide linkage. MEP studies specified their reactive sites of binding. Finally, a synthetic protocol using less toxic reagents has been designed for their synthesis and an in vitro antioxidant activity has been evaluated.
Synthesis, Crystal and Hirshfeld Surface Structure of a 1D Ni(II) Coordination Polymer: Luminescent Detection for Fe3+ in H2O
Authors: Ya‐Li  , Zhao  , Li Jia‐Ming
Published: April 2021

A one‐dimensional (1D) Ni(II) coordination polymer, {[Ni(oba)(1,3‐bix)(H2O)]⋅H2O}n (1), where H2oba=4,4′‐oxybis(benzoic acid) and 1,3‐bis(imidazol‐l‐yl‐methyl)benzene=1,3‐bix, was hydrothermally synthesized and characterized through IR spectroscopy, elemental and thermal analysis, single‐crystal X‐ray diffraction, and Hirshfeld surface analyses. X‐ray diffraction structural analysis has revealed that the oba and 1,3‐bix ligands connects the Ni(II) atoms to form a square‐wave 1D chain, which is further extended into 2D supramolecular layers through O−H⋅⋅⋅O hydrogen bonds and π⋅⋅⋅π stacking interactions. 1 shows intense luminescence in H2O and exhibits a selectivity and detection for Fe3+ ions through the fluorescence quenching effect at room temperature.
Applications of Yamaguchi Method to Esterification and Macrolactonization in Total Synthesis of Bioactive Natural Products
Authors: Majhi Sasadhar
Published: April 2021

Yamaguchi protocol provides functionalized esters regioselectively from carboxylic acids and alcohols employing 2,4,6‐trichlorobenzoyl chloride as the condensation reagent in the presence of a stoichiometric amount of 4‐N,N‐dimethylaminopyridine. The key features of this method comprise a high yield of esters, short reaction time, mild conditions, macrocyclic lactone ring formation, and regioselective preparation of highly functionalized esters. Such beneficial quality of this method as a whole have motivated the organic chemist and biological community to explore the application of Yamaguchi protocol in more heights and as a result, the present overview is aimed to cover the application of this method as a key step in the area of the total synthesis of bioactive natural products. The present review tries to focus on the natural sources, structures, and biological activities of the promising natural products elegantly.
Study on the Preparation of Zn‐Al‐LDHs by Different Reaction Methods with Ion Exchange Resin
Authors: Wang Ying , Sun Jiahan
Published: April 2021

Zn‐Al layered double hydroxides (Zn‐Al‐LDHs) were successfully prepared with ion exchange resin and mixed hydroxide by pneumatic stirring, constant temperature oscillation, magnetic stirring and hydrothermal reaction methods. The products were characterized by SEM, EDS, XRD, FT‐IR and TG‐DSC. The advantages and disadvantages of various preparation methods were compared systematically. On the basis of the unique internal structure of ion exchange resin, the resin could effectively control the rate of product generation, and ensure the formation of LDHs slowly and evenly in the whole solution, so that the product morphology was more uniform and dispersed, and the product could be used directly without washing. SEM and XRD results show that the single constant temperature oscillation method and magnetic stirring method could obtain the products with better micromorphology than the pneumatic stirring method, presenting a clear hexagonal sheet structure. At the same time, the two methods can obtain nanoscale Zn‐Al‐LDHs with better crystal structure and higher purity. FT‐IR and TG‐DSC characterization further confirmed the composition of the product and the carbonate intercalation structure of the hydrotalcite.
Cu(OH)2 Nanorods/Ni(OH)2 Nanosheets as Highly Efficient Catalyst for Hydrogen Evolution Reaction
Authors: Hu Junping , Liu Youxing
Published: April 2021

Reasonably designing the catalyst in‐situ grown on conductive substrate is a promising avenue to ameliorate the hydrogen evolution reaction (HER). In this work, we fabricated Cu(OH)2 nanorods (NRs) and Ni(OH)2 nanosheets (NSs) on single crystal Cu foil for the first time. The structure and morphology of all samples were systematically investigated by XRD and SEM, respectively. XPS was carried out to measure the element composition and valence state. The synergistic effect of metal double hydroxides significantly improved the catalytic performance of hydrogen evolution in neutral electrolytes. And it also showed a high catalytic stability. The overpotential at 10 mA/cm2 and Tafel slope of Cu(OH)2 NRs @ Ni(OH)2 NSs were 200 mV and 120 mV/dec, respectively, which was markedly better than other materials reported previously.
Synthesis and Stereochemical Behavior of Dioxa[6]helicene Derivatives
Authors: Shyam Sundar M. , Lo Rabindranath , Dračínský Martin , Klepetářová Blanka
Published: April 2021

We constructed a helically chiral dioxa[6]helicene by assembling simple phenol building blocks by a combination of two simple reactions involving oxidative cross‐coupling followed by dehydrative cyclization. X‐ray analysis and density functional calculations (DFT) revealed that the compound dioxa[6]helicene has a helical structure that undergoes helical inversion rapidly at room temperature. We were able to detect the presence of resolvable helical isomers of (−)‐menthyloxycarbonyl derivative of dioxa[6]helicene by recording 1H NMR spectra below 0 °C. The investigations of photo physical properties by cyclic voltammetry, UV/Vis‐ and fluorescence properties with the aid of time‐dependent DFT calculations were undertaken.
Hydrothermal Stable Pd/γ‐Al2O3 @PA for Selective Conversion of Glutamic Acid to Bio‐Based 2‐Pyrrolidone
Authors: Shi Xiaoyu , Ye Xin , Cheng Jiong , Wang Xiaoguang , Chen Pengfei , Yang Yang , Wang Tianfu
Published: April 2021

Glutamic acid conversion to 2‐pyrrolidone provides significant effort in recycling nitrogen from nitrogen‐rich waste streams, particularly protein waste. Catalysts with good performance for this reaction have been suffered with unstableness and the disability in controlling the product selectivity. Here, by modifying the support with H3PO4 (PA), we got stable Pd/γ‐Al2O3 @PA catalyst, which not only enhanced 2‐pyrrolidone production from glutamic acid hydrothermal conversion, but more importantly, increased product selectivity by surface Brønsted acid sites. This study offered a robust and economic strategy to stabilize metal oxide‐supported catalysts, and could lead to additional merits in controlling the product selectivity by modulating the near‐surface environment.
Morphological–phylogenetic analysis of the late Cenozoic Chlamydini von Teppner (Bivalvia, Pectinidae) of southern South America
Authors: Santelli María Belén , Alvarez Maximiliano J. , del Río Claudia J.
Published: April 2021

The tribe Chlamydini was highly diversified in the marine Neogene of southern South America, reaching its maximum taxonomic diversity during the Miocene. However, the evolutionary relationships of South American taxa remain uncertain. This is the first phylogenetic analysis based on a large morphological matrix on Pectinidae, which focuses on South American taxa and species related to Chlamys s.s. The phylogenetic analysis is based on a matrix composed of 145 shell‐characters scored for 48 species, and multiple searches were conducted using equal and implied weighting. Two new monophyletic clades are defined, Multiplicata and Pauciplicata. The first includes Dietotenhosen, Ckaraosippur, Zygochlamys, Moirechlamys (South America), the North‐West Pacific Azumapecten, and the North‐East Pacific Chlamys hastata. Pauciplicata is represented by Chokekenia (Patagonia, Argentina), Laevichlamys (tropical Atlantic and Indo‐Pacific), Semipallium (Indo‐Pacific), Swiftopecten (South America and North Pacific), and Jorgechlamys + Reticulochlamys (Patagonia, Argentina). All of these genera are monophyletic except for the paraphyletic Jorgechlamys. The oldest documented occurrence of the tribe is Semipallium foulcheri from the lower Oligocene, a derived taxon that pushes the divergence time of basal genera to the Eocene–Oligocene boundary, generating ghost lineages in all clades, except Jorgechlamys + Reticulochlamys. Pauciplicata and Multiplicata diverge in the early history of the tribe, at the Eocene–Oligocene boundary. Future analyses are necessary to gain a better understanding of the taxonomic arrangement of this poorly understood tribe. Further insights into the relationships of its deepest nodes may well resolve many ghost lineages.
Temporal trajectories in metacommunity structure: Insights from interdisciplinary research in intermittent streams
Authors: Perkin Joshuah S. , Papraniku Isabel F. , Gibbs W. Keith , Hoeinghaus David J. , Walker Donald M.
Published: April 2021

Metacommunity ecology represents a framework for identifying linkages between environmental heterogeneity, spatial processes, and local communities of organisms. Despite advancements in metacommunity theory, there remains a need to understand temporal dynamics of multi‐taxa metacommunities in variable ecosystems such as intermittent streams. We present a review of literature, three recent conceptual models, and a case study regarding metacommunity temporal dynamics in intermittent streams. The literature review revealed that the cumulative number of studies addressing temporal dynamics in aquatic metacommunities steadily increased between 2012 and 2020. Intermittent streams were the fourth‐most commonly studied ecosystem and interdisciplinary studies involving multiple taxa were the third‐most common taxonomic focus. The most common analytical method was variation partitioning, and analysis of beta diversity components surpassed both distance decay and elements of metacommunity structure as the second‐most used method from 2018 to 2020. Three recent conceptual models describing metacommunity dynamics in intermittent streams predict: (a) higher local species richness (i.e., alpha diversity) during rewetting and wet hydrologic phases, (b) stronger effects of dispersal over environmental sorting during the rewetting and wet phases, and (c) emergence of primarily nested structures during the wet hydrologic phase. When tested in a case study focused on microbes, aquatic invertebrates, and fishes, each of these predictions were partially, but not completely supported. Our results reveal expanding interest in temporal aspects of aquatic metacommunity structure and highlight how research in intermittent streams is poised to simultaneously advance basic metacommunity ecology and applied conservation biology through continued refinement of new and existing conceptual syntheses.

This article is categorized under:

Water and Life > Nature of Freshwater Ecosystems

Water and Life > Stresses and Pressures on Ecosystems

Water and Life > Conservation, Management, and Awareness
Top, Higgs, diboson and electroweak fit to the Standard Model effective field theory
Authors: Ellis John , Madigan Maeve , Mimasu Ken , Sanz Veronica , You Tevong
Published: April 2021

Abstract

The search for effective field theory deformations of the Standard Model (SM) is a major goal of particle physics that can benefit from a global approach in the framework of the Standard Model Effective Field Theory (SMEFT). For the first time, we include LHC data on top production and differential distributions together with Higgs production and decay rates and Simplified Template Cross-Section (STXS) measurements in a global fit, as well as precision electroweak and diboson measurements from LEP and the LHC, in a global analysis with SMEFT operators of dimension 6 included linearly. We present the constraints on the coefficients of these operators, both individually and when marginalised, in flavour-universal and top-specific scenarios, studying the interplay of these datasets and the correlations they induce in the SMEFT. We then explore the constraints that our linear SMEFT analysis imposes on specific ultra-violet completions of the Standard Model, including those with single additional fields and low-mass stop squarks. We also present a model-independent search for deformations of the SM that contribute to between two and five SMEFT operator coefficients. In no case do we find any significant evidence for physics beyond the SM. Our underlying Fitmaker public code provides a framework for future generalisations of our analysis, including a quadratic treatment of dimension-6 operators.
Universality in asymptotic bounds and its saturation in 2D CFT
Authors: Das Diptarka , Kusuki Yuya , Pal Sridip
Published: April 2021

Abstract

We study asymptotics of three point coefficients (light-light-heavy) and two point correlators in heavy states in unitary, compact 2D CFTs. We prove an upper and lower bound on such quantities using numerically assisted Tauberian techniques. We obtain an optimal upper bound on the spectrum of operators appearing with fixed spin from the OPE of two identical scalars. While all the CFTs obey this bound, rational CFTs come close to saturating it. This mimics the scenario of bounds on asymptotic density of states and thereby pronounces an universal feature in asymptotics of 2D CFTs. Next, we clarify the role of smearing in interpreting the asymptotic results pertaining to considerations of eigenstate thermalization in 2D CFTs. In the context of light-light-heavy three point coefficients, we find that the order one number in the bound is sensitive to how close the light operators are from the $$ \frac{c}{32} $$

c
32

threshold. In context of two point correlator in heavy state, we find the presence of an enigmatic regime which separates the AdS3 thermal physics and the BTZ black hole physics. Furthermore, we present some new numerical results on the behaviour of spherical conformal block.
Subordination for sequentially equicontinuous equibounded $$C_0$$-semigroups
Authors: Kruse Karsten , Meichsner Jan , Seifert Christian
Published: April 2021

We consider operators A on a sequentially complete Hausdorff locally convex space X such that $$-A$$

-
A

generates a (sequentially) equicontinuous equibounded $$C_0$$

C
0

-semigroup. For every Bernstein function f we show that $$-f(A)$$

-
f
(
A
)

generates a semigroup which is of the same ‘kind’ as the one generated by $$-A$$

-
A

. As a special case we obtain that fractional powers $$-A^{\alpha }$$

-

A
α

, where $$\alpha \in (0,1)$$

α
∈
(
0
,
1
)

, are generators.
Fujita modified exponent for scale invariant damped semilinear wave equations
Authors: Chiarello Felisia Angela , Girardi Giovanni , Lucente Sandra
Published: April 2021

The aim of this paper is to prove a blow-up result of the solution for a semilinear scale invariant damped wave equation under a suitable decay condition on radial initial data. The admissible range for the power of the nonlinear term depends both on the damping coefficient and on the pointwise decay order of the initial data. In addition, we give an upper bound estimate for the lifespan of the solution. It depends not only on the exponent of the nonlinear term and not only on the damping coefficient but also on the size of the decay rate of the initial data.
Relaxed parameter conditions for chemotactic collapse in logistic-type parabolic–elliptic Keller–Segel systems
Authors: Black Tobias , Fuest Mario , Lankeit Johannes
Published: April 2021

We study the finite-time blow-up in two variants of the parabolic–elliptic Keller–Segel system with nonlinear diffusion and logistic source. In n-dimensional balls, we consider $$\begin{aligned} {\left\{ \begin{array}{ll} u_t = \nabla \cdot ((u+1)^{m-1}\nabla u -u \nabla v) + \lambda u - \mu u^{1+\kappa }, \\ 0 = \Delta v - \frac{1}{|\Omega |} \int \limits _\Omega u + u \end{array}\right. } \end{aligned}$$

u
t

=
∇
·

(

(
u
+
1
)

m
-
1

∇
u
-
u
∇
v
)

+
λ
u
-
μ

u

1
+
κ

,

0
=
Δ
v
-

1

|
Ω
|

∫
Ω

u
+
u

and $$\begin{aligned} {\left\{ \begin{array}{ll} u_t = \nabla \cdot ((u+1)^{m-1}\nabla u -u \nabla v) + \lambda u - \mu u^{1+\kappa }, \\ 0 = \Delta v - v + u, \end{array}\right. } \end{aligned}$$

u
t

=
∇
·

(

(
u
+
1
)

m
-
1

∇
u
-
u
∇
v
)

+
λ
u
-
μ

u

1
+
κ

,

0
=
Δ
v
-
v
+
u
,

where $$\lambda $$
λ
and $$\mu $$
μ
are given spatially radial nonnegative functions and $$m, \kappa > 0$$

m
,
κ
>
0

are given parameters subject to further conditions. In a unified treatment, we establish a bridge between previously employed methods on blow-up detection and relatively new results on pointwise upper estimates of solutions in both of the systems above and then, making use of this newly found connection, provide extended parameter ranges for $$m,\kappa $$

m
,
κ

leading to the existence of finite-time blow-up solutions in space dimensions three and above. In particular, for constant $$\lambda , \mu > 0$$

λ
,
μ
>
0

, we find that there are initial data which lead to blow-up in (JL) if $$\begin{aligned} 0 \le \kappa&< \min \left\{ \frac{1}{2}, \frac{n - 2}{n} - (m-1)_+ \right\}&\quad \text {if } m\in \left[ \frac{2}{n},\frac{2n-2}{n}\right) \\ \text { or }\quad 0 \le \kappa&<\min \left\{ \frac{1}{2},\frac{n-1}{n}-\frac{m}{2}\right\}&\quad \text {if } m\in \left( 0,\frac{2}{n}\right) , \end{aligned}$$

0
≤
κ

<
min

1
2

,

n
-
2

n

-

(
m
-
1
)

+

if

m
∈

2
n

,

2
n
-
2

n

or

0
≤
κ

<
min

1
2

,

n
-
1

n

-

m
2

if

m
∈

0
,

2
n

,

and in (PE) if $$m \in [1, \frac{2n-2}{n})$$

m
∈
[
1
,

2
n
-
2

n

)

and $$\begin{aligned} 0 \le \kappa < \min \left\{ \frac{(m-1) n + 1}{2(n-1)}, \frac{n - 2 - (m-1) n}{n(n-1)} \right\} . \end{aligned}$$

0
≤
κ
<
min

(
m
-
1
)
n
+
1

2
(
n
-
1
)

,

n
-
2
-
(
m
-
1
)
n

n
(
n
-
1
)

.
Ein Airbag kann auch tödlich sein
Authors: Hahn M. , Dreimann M. , Matschke J. , Lohner L. , Püschel K.
Published: April 2021

Es wird das Verletzungsschema eines Fahrers nach Frontalzusammenstoß mit Airbag-Auslösung bei nichtangelegtem Gurt dargestellt. Der Patient wies bei Erstuntersuchung nur geringe äußere Verletzungen auf. Im CT zeigte sich eine nichtdislozierte Densfraktur. Im späteren MRT waren eine sekundäre Dislokation der Fraktur mit Myelonkontusion und diskoligamentäre Zerreißungen bei C5–T1 zu erkennen. Nach operativer Versorgung verstarb der Patient an den Folgen eines kompletten Querschnittsyndroms. Bei der Sektion fanden sich eine Hirnschwellung und eine Quetschungszone im oberen Halsmark. Unerwartet bestanden hier keine Blutungen und Einreißungen des Gewebes. Es wird auf die strukturelle Besonderheit des Axis eingegangen und das Unfallgeschehen anhand des Verletzungsmusters sowie der Sektionsbefunde rekonstruiert.
Immune infiltrate diversity confers a good prognosis in follicular lymphoma
Authors: Tsakiroglou Anna-Maria , Astley Susan , Dave Manàs , Fergie Martin , Harkness Elaine , Rosenberg Adeline , Sperrin Matthew , West Catharine , Byers Richard , Linton Kim
Published: April 2021

Background

Follicular lymphoma (FL) prognosis is influenced by the composition of the tumour microenvironment. We tested an automated approach to quantitatively assess the phenotypic and spatial immune infiltrate diversity as a prognostic biomarker for FL patients.

Methods

Diagnostic biopsies were collected from 127 FL patients initially treated with rituximab-based therapy (52%), radiotherapy (28%), or active surveillance (20%). Tissue microarrays were constructed and stained using multiplex immunofluorescence (CD4, CD8, FOXP3, CD21, PD-1, CD68, and DAPI). Subsequently, sections underwent automated cell scoring and analysis of spatial interactions, defined as cells co-occurring within 30 μm. Shannon’s entropy, a metric describing species biodiversity in ecological habitats, was applied to quantify immune infiltrate diversity of cell types and spatial interactions. Immune infiltrate diversity indices were tested in multivariable Cox regression and Kaplan–Meier analysis for overall (OS) and progression-free survival (PFS).

Results

Increased diversity of cell types (HR = 0.19 95% CI 0.06–0.65, p = 0.008) and cell spatial interactions (HR = 0.39, 95% CI 0.20–0.75, p = 0.005) was associated with favourable OS, independent of the Follicular Lymphoma International Prognostic Index. In the rituximab-treated subset, the favourable trend between diversity and PFS did not reach statistical significance.

Conclusion

Multiplex immunofluorescence and Shannon’s entropy can objectively quantify immune infiltrate diversity and generate prognostic information in FL. This automated approach warrants validation in additional FL cohorts, and its applicability as a pre-treatment biomarker to identify high-risk patients should be further explored. The multiplex image dataset generated by this study is shared publicly to encourage further research on the FL microenvironment.
Different phenotypes of neuropsychiatric systemic lupus erythematosus are related to a distinct pattern of structural changes on brain MRI
Authors: Inglese Francesca , Kant Ilse M. J. , Monahan Rory C. , Steup-Beekman Gerda M. , Huizinga Tom W. J. , van Buchem Mark A. , Magro-Checa Cesar , Ronen Itamar , de Bresser Jeroen
Published: April 2021

Objectives

The underlying structural brain correlates of neuropsychiatric involvement in systemic lupus erythematosus (NPSLE) remain unclear, thus hindering correct diagnosis.

We compared brain tissue volumes between a clinically well-defined cohort of patients with NPSLE and SLE patients with neuropsychiatric syndromes not attributed to SLE (non-NPSLE). Within the NPSLE patients, we also examined differences between patients with two distinct disease phenotypes: ischemic and inflammatory.

Methods

In this prospective (May 2007 to April 2015) cohort study, we included 38 NPSLE patients (26 inflammatory and 12 ischemic) and 117 non-NPSLE patients. All patients underwent a 3-T brain MRI scan that was used to automatically determine white matter, grey matter, white matter hyperintensities (WMH) and total brain volumes. Group differences in brain tissue volumes were studied with linear regression analyses corrected for age, gender, and total intracranial volume and expressed as B values and 95% confidence intervals.

Results

NPSLE patients showed higher WMH volume compared to non-NPSLE patients (p = 0.004). NPSLE inflammatory patients showed lower total brain (p = 0.014) and white matter volumes (p = 0.020), and higher WMH volume (p = 0.002) compared to non-NPSLE patients. Additionally, NPSLE inflammatory patients showed lower white matter (p = 0.020) and total brain volumes (p = 0.038) compared to NPSLE ischemic patients.

Conclusion

We showed that different phenotypes of NPSLE were related to distinct patterns of underlying structural brain MRI changes. Especially the inflammatory phenotype of NPSLE was associated with the most pronounced brain volume changes, which might facilitate the diagnostic process in SLE patients with neuropsychiatric symptoms.

Key Points

• Neuropsychiatric systemic lupus erythematosus (NPSLE) patients showed a higher WMH volume compared to SLE patients with neuropsychiatric syndromes not attributed to SLE (non-NPSLE).

• NPSLE patients with inflammatory phenotype showed a lower total brain and white matter volume, and a higher volume of white matter hyperintensities, compared to non-NPSLE patients.

• NPSLE patients with inflammatory phenotype showed lower white matter and total brain volumes compared to NPSLE patients with ischemic phenotype.
Correlation Structures between Satellite All-Sky Infrared Brightness Temperatures and the Atmospheric State at Storm Scales
Authors: Zhang Yunji , Clothiaux Eugene E. , Stensrud David J.
Published: April 2021

This study explores the structures of the correlations between infrared (IR) brightness temperatures (BTs) from the three water vapor channels of the Advanced Baseline Imager (ABI) onboard the GOES-16 satellite and the atmospheric state. Ensemble-based data assimilation techniques such as the ensemble Kalman filter (EnKF) rely on correlations to propagate innovations of BTs to increments of model state variables. Because the three water vapor channels are sensitive to moisture in different layers of the troposphere, the heights of the strongest correlations between these channels and moisture in clear-sky regions are closely related to the peaks of their respective weighting functions. In cloudy regions, the strongest correlations appear at the cloud tops of deep clouds, and ice hydrometeors generally have stronger correlations with BT than liquid hydrometeors. The magnitudes of the correlations decrease from the peak value in a column with both vertical and horizontal distance. Just how the correlations decrease depend on both the cloud scenes and the cloud structures, as well as the model variables. Horizontal correlations between BTs and moisture, as well as hydrometeors, in fully cloudy regions decrease to almost 0 at about 30 km. The horizontal correlations with atmospheric state variables in clear-sky regions are broader, maintaining non-zero values out to ∼100 km. The results in this study provide information on the proper choice of cut-off radii in horizontal and vertical localization schemes for the assimilation of BTs. They also provide insights on the most efficient and effective use of the different water vapor channels.
Neurological update: COVID-19
Authors: Ren A. L. , Digby R. J. , Needham E. J.
Published: April 2021

Coronavirus Disease 2019 is predominantly a disorder of the respiratory system, but neurological complications have been recognised since early in the pandemic. The major pathophysiological processes leading to neurological damage in COVID-19 are cerebrovascular disease, immunologically mediated neurological disorders and the detrimental effects of critical illness on the nervous system. It is still unclear whether direct invasion of the nervous system by the Severe Acute Respiratory Syndrome Coronavirus 2 occurs; given the vast numbers of people infected at this point, this uncertainty suggests that nervous system infection is unlikely to represent a significant issue if it occurs at all. In this review, we explore what has been learnt about the neurological complications of COVID-19 over the course of the pandemic, and by which mechanisms these complications most commonly occur.
Modelling Rock Fracture Induced By Hydraulic Pulses
Authors: Xi Xun , Yang Shangtong , McDermott Christopher I. , Shipton Zoe K. , Fraser-Harris Andrew , Edlmann Katriona
Published: April 2021

Soft cyclic hydraulic fracturing has become an effective technology used in subsurface energy extraction which utilises cyclic hydraulic flow pressure to fracture rock. This new technique induces fatigue of rock to reduce the breakdown pressure and potentially the associated risk of seismicity. To control the fracturing process and achieve desirable fracture networks for enhanced permeability, the rock response under cyclic hydraulic stimulation needs to be understood. However, the mechanism for cyclic stimulation-induced fatigue of rock is rather unclear and to date there is no implementation of fatigue degradation in modelling the rock response under hydraulic cyclic loading. This makes accurate prediction of rock fracture under cyclic hydraulic pressure impossible. This paper develops a numerical method to model rock fracture induced by hydraulic pulses with consideration of rock fatigue. The fatigue degradation is based on S–N curves (S for cyclic stress and N for cycles to failure) and implemented into the constitutive relationship for fracture of rock using in-house FORTRAN scripts and ABAQUS solver. The cohesive crack model is used to simulate discrete crack propagation in the rock which is coupled with hydraulic flow and pore pressure capability. The developed numerical model is validated via experimental results of pulsating hydraulic fracturing of the rock. The effects of flow rate and frequency of cyclic injection on borehole pressure development are investigated. A new loading strategy for pulsating hydraulic fracturing is proposed. It has been found that hydraulic pulses can reduce the breakdown pressure of rock by 10–18% upon 10–4000 cycles. Using the new loading strategy, a slow and steady rock fracture process is obtained while the failure pressure is reduced.
Holistic simulation of wind turbines with fully aero-elastic and electrical model
Authors: Wiens Marcus , Frahm Sebastian , Thomas Philipp , Kahn Shoaib
Published: April 2021

Requirements for the design of wind turbines advance facing the challenges of a high content of renewable energy sources in the public grid. A high percentage of renewable energy weaken the grid and grid faults become more likely, which add additional loads on the wind turbine. Load calculations with aero-elastic models are standard for the design of wind turbines. Components of the electric system are usually roughly modeled in aero-elastic models and therefore the effect of detailed electrical models on the load calculations is unclear. A holistic wind turbine model is obtained, by combining an aero-elastic model and detailed electrical model into one co-simulation. The holistic model, representing a DFIG turbine is compared to a standard aero-elastic model for load calculations. It is shown that a detailed modelling of the electrical components e.g., generator, converter, and grid, have an influence on the results of load calculations. An analysis of low-voltage-ride-trough events during turbulent wind shows massive increase of loads on the drive train and effects the tower loads. Furthermore, the presented holistic model could be used to investigate different control approaches on the wind turbine dynamics and loads. This approach is applicable to the modelling of a holistic wind park to investigate interaction on the electrical level and simultaneously evaluate the loads on the wind turbine.
Optimierung des Eigenspannungszustands kaltfließgepresster austenitischer Stähle durch einen kontrollierten Ausstoßvorgang
Authors: Jaeger Fabian , Franceschi Alessandro , Hoche Holger , Groche Peter , Oechsner Matthias
Published: April 2021

Ausgehend von vorherigen Ergebnissen zur Prozessoptimierung fließgepresster Proben aus dem austenitischen Werkstoff 1.4404 mittels einer aktiven Prozessführung zur Verbesserung des Eigenspannungszustands, wurde das gleiche Verfahren auf den metastabilen austenitischen Werkstoff 1.4307 angewandt. Es wurden neue Erkenntnisse erwartet, da dieses Material bereits bei geringen Umformgraden zur Bildung von verformungsinduziertem Martensit neigt. Zum Vergleich der erwarteten Optimierung des Eigenspannungszustands wurden konventionell fließgepresste Proben hegestellt und spannungsarmgeglüht.

Es wurde gezeigt, dass die Reduktion der Zugeigenspannungen durch die aktive Prozessführung beim 1.4307 insbesondere in der martensitischen Phase auftritt, während diese beim 1.4404 im Austenit erfolgt. Durch einen zusätzlichen Prozessschritt der Wärmebehandlung konventionell fließgepresster Proben werden ebenfalls Zugeigenspannungen abgebaut. Allerdings zeigt die Kaltumformung mit aktiver Prozessführung ein höheres Potenzial zur Verbesserung des Eigenspannungszustands.
Gezielte Steuerung der Bauteileigenspannungen durch inkrementelle Blechumformung
Authors: Maaß Fabian , Dobecki Mateus , Hahn Marlon , Reimers Walter , Tekkaya A. Erman
Published: April 2021

Die Prozessführung der inkrementellen Blechumformung beeinflusst maßgeblich den Eigenspannungszustand einer gefertigten Komponente und damit die Produkteigenschaften. Eine kontinuierliche Variation des Zustellinkrements im Umformprozess ermöglicht die lokale Ausbildung vordefinierter Eigenspannungen im Bauteil. Um die lokale Beeinflussung von Eigenspannungen zu analysieren, werden vier Prozessrouten mit unterschiedlichen Zustellinkrement-Kombinationen zur Herstellung einer Kegelstumpfgeometrie experimentell verglichen. Eine Änderung der Zustellinkremente im Prozess verursacht eine Erhöhung des Eigenspannungsniveaus bei sonst gleichbleibenden Produkteigenschaften.
“Keep it simple, scholar”: an experimental analysis of few-parameter segmentation networks for retinal vessels in fundus imaging
Authors: Fu Weilin , Breininger Katharina , Schaffert Roman , Pan Zhaoya , Maier Andreas
Published: April 2021

Purpose

With the recent development of deep learning technologies, various neural networks have been proposed for fundus retinal vessel segmentation. Among them, the U-Net is regarded as one of the most successful architectures. In this work, we start with simplification of the U-Net, and explore the performance of few-parameter networks on this task.

Methods

We firstly modify the model with popular functional blocks and additional resolution levels, then we switch to exploring the limits for compression of the network architecture. Experiments are designed to simplify the network structure, decrease the number of trainable parameters, and reduce the amount of training data. Performance evaluation is carried out on four public databases, namely DRIVE, STARE, HRF and CHASE_DB1. In addition, the generalization ability of the few-parameter networks are compared against the state-of-the-art segmentation network.

Results

We demonstrate that the additive variants do not significantly improve the segmentation performance. The performance of the models are not severely harmed unless they are harshly degenerated: one level, or one filter in the input convolutional layer, or trained with one image. We also demonstrate that few-parameter networks have strong generalization ability.

Conclusion

It is counter-intuitive that the U-Net produces reasonably good segmentation predictions until reaching the mentioned limits. Our work has two main contributions. On the one hand, the importance of different elements of the U-Net is evaluated, and the minimal U-Net which is capable of the task is presented. On the other hand, our work demonstrates that retinal vessel segmentation can be tackled by surprisingly simple configurations of U-Net reaching almost state-of-the-art performance. We also show that the simple configurations have better generalization ability than state-of-the-art models with high model complexity. These observations seem to be in contradiction to the current trend of continued increase in model complexity and capacity for the task under consideration.
Differences in Health-Related Quality of Life After Gastric Bypass Surgery: a Cross-Sectional Study
Authors: Antonsson Tobias , Wennersten André , Sörensen Kaisa , Regnér Sara , Ekelund Mikael
Published: April 2021

Background

Gastric bypass (GBP) is a surgical method with good evidence of sustainable weight loss, reduced obesity-related comorbidities, and improved health-related quality of life (HRQoL). However, long-term data post-GBP is scarce on HRQoL related to other factors than weight loss, such as impact of socio-economic, age, and gender.

Aim

To investigate long-term HRQoL in GBP patients.

Methods

The study was conducted as a cross-sectional study covering 3 to 9 years post-GBP measuring HRQoL using RAND-36. Association to weight loss, time since surgery, gender, educational level, occupation, and age was analyzed. The participants were included on the basis that they had received a GBP that was performed by Region Skåne, the southernmost administrative healthcare region in Sweden. Recruitment to the study was by mail invitation for an online survey.

Results

Of the total population of 5310 persons receiving the questionnaire, 1339 of the 1372 responders fulfilled the inclusion criteria. Those with low educational level, unemployed, persons on sick leave or disability support, and those with less weight loss reported the lowest HRQoL. The longer time since surgery, the lower the HRQoL.

Conclusion

Less weight loss, longer time since GBP, lower educational level, and lower degree of employment all affect HRQoL negatively after GBP surgery.

Graphical abstract
The impact of articulatory consciousness training on reading and spelling literacy in students with severe dyslexia: an experimental single case study
Authors: Thurmann-Moe Anne Cathrine , Melby-Lervåg Monica , Lervåg Arne
Published: April 2021

This study evaluates the effect of an intervention whose aim is to make articulatory consciousness a tool in decoding and spelling. The sample comprises 11 students with severe dyslexia (2 SD below the mean pseudoword scores), and the intervention programme consists of 32 individual sessions over 8 weeks. The study applies a multiple baseline/probe design with five baseline tests that correspond to a control condition, eight tests during the intervention and five post-intervention tests. On average, the results show significant improvement in all reading and spelling outcomes. However, there were also significant effects on an irrelevant control task (the pegboard test), perhaps indicating testing effects on the dependent variables, making it difficult to draw firm conclusions from the study. Consequently, testing the intervention in randomised trials of children with severe dyslexia is recommended to draw more firm conclusions about its efficacy for this group.
We Mostly Think Alike: Individual Differences in Attitude Towards AI in Sweden and Japan
Authors: Persson Anders , Laaksoharju Mikael , Koga Hiroshi
Published: April 2021

Attitudes towards artificial intelligence (AI) and social robots are often depicted as different in Japan, compared to other western countries, such as Sweden. Several different reasons for why there are general differences in attitudes have been suggested. In this study, five hypotheses based on previous literature were investigated. Rather than attempting to establish general differences between groups, subjects were sampled from the respective populations, and correlations between the hypothesized confounding factors and attitudes were investigated within the groups between individuals. The hypotheses in this exploratory study concerned: (H1) animistic beliefs in inanimate objects and phenomena, (H2) worry about unemployment due to AI deployment, (H3) perceived positive or negative portrayal of AI in popular culture, (H4) familiarity with AI, and (H5) relational closeness and privacy with AI. No clear correlations between attitudes and animistic belief (H1), or portrayal of AI in popular culture (H3) could be observed. When it comes to the other attributes, worry about unemployment (H2), familiarity with AI (H4), and relational closeness and privacy (H5), the correlations were similar for the individuals in both groups and in line with the hypotheses. Thus, the general picture following this exploratory study is that individuals in the two populations are more alike than different.
Enhanced Reversible Zinc Ion Intercalation in Deficient Ammonium Vanadate for High-Performance Aqueous Zinc-Ion Battery
Authors: Zong Quan , Du Wei , Liu Chaofeng , Yang Hui , Zhang Qilong , Zhou Zheng , Atif Muhammad , Alsalhi Mohamad , Cao Guozhong
Published: April 2021

Ammonium vanadate with bronze structure (NH4V4O10) is a promising cathode material for zinc-ion batteries due to its high specific capacity and low cost. However, the extraction of $${\text{NH}}_{{4}}^{ + }$$

NH

4

+

at a high voltage during charge/discharge processes leads to irreversible reaction and structure degradation. In this work, partial $${\text{NH}}_{{4}}^{ + }$$

NH

4

+

ions were pre-removed from NH4V4O10 through heat treatment; NH4V4O10 nanosheets were directly grown on carbon cloth through hydrothermal method. Deficient NH4V4O10 (denoted as NVO), with enlarged interlayer spacing, facilitated fast zinc ions transport and high storage capacity and ensured the highly reversible electrochemical reaction and the good stability of layered structure. The NVO nanosheets delivered a high specific capacity of 457 mAh g−1 at a current density of 100 mA g−1 and a capacity retention of 81% over 1000 cycles at 2 A g−1. The initial Coulombic efficiency of NVO could reach up to 97% compared to 85% of NH4V4O10 and maintain almost 100% during cycling, indicating the high reaction reversibility in NVO electrode.