bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of ZnO nanorods with plasmonic metal nanoparticles and semiconductor quantum dots
Authors: Prajapati K. N. , Johns Ben , Bandopadhyay K. , Silva S. Ravi P. , Mitra J.
Published: February 2020

We model the enhancement of near band edge emission from ZnO nanorods using plasmonic metal nanoparticles and compare it with emission enhancement from ZnO with semiconducting quantum dots. Selected CdSe quantum dots with absorption energies close to those of Ag and Au nanoparticles are chosen to construct model systems with ZnO to comprehend the role of ZnO’s intrinsic defects and plasmonic excitation in realizing the spectrally selective luminescence enhancement. Excitation wavelength dependent photoluminescence spectra along with theoretical models quantifying the related transitions and plasmonic absorption reveal that a complex mechanism of charge transfer between the ZnO nanorods and metal nanoparticles or quantum dots is essential along with an optimal energy band alignment for realizing emission enhancement. The theoretical model presented also provides a direct method of quantifying the relative transition rate constants associated with various electronic transitions in ZnO and their change upon the incorporation of plasmonic nanoparticles. The results indicate that, while the presence of deep level defect states may facilitate the essential charge transfer process between ZnO and the plasmonic nanoparticles, their presence alone does not guarantee UV emission enhancement and strong plasmonic coupling between the two systems. The results offer clues to designing novel multicomponent systems with coupled plasmonic and charge transfer effects for applications in charge localization, energy harvesting, and luminescence enhancement, especially in electrically triggered nanophotonic applications.
Adsorption and reaction of methanol on Fe3O4(001)
Authors: Marcinkowski Matthew D. , Adamsen Kræn C. , Doudin Nassar , Sharp Marcus A. , Smith R. Scott , Wang Yang , Wendt Stefan , Lauritsen Jeppe V. , Parkinson Gareth S. , Kay Bruce D. , Dohnálek Zdenek
Published: February 2020

The interaction of methanol with iron oxide surfaces is of interest due to its potential in hydrogen storage and from a fundamental perspective as a chemical probe of reactivity. We present here a study examining the adsorption and reaction of methanol on magnetite Fe3O4(001) at cryogenic temperatures using a combination of temperature programmed desorption, x-ray photoelectron spectroscopy, and scanning tunneling microscopy. The methanol desorption profile from Fe3O4(001) is complex, exhibiting peaks at 140 K, 173 K, 230 K, and 268 K, corresponding to the desorption of intact methanol, as well as peaks at 341 K and 495 K due to the reaction of methoxy intermediates. The saturation of a monolayer of methanol corresponds to ∼5 molecules/unit cell (u.c.), which is slightly higher than the number of surface octahedral iron atoms of 4/u.c. We probe the kinetics and thermodynamics of the desorption of molecular methanol using inversion analysis. The deconvolution of the complex desorption profile into individual peaks allows for calculations of both the desorption energy and the prefactor of each feature. The initial 0.7 methanol/u.c. reacts to form methoxy and hydroxy intermediates at 180 K, which remain on the surface above room temperature after intact methanol has desorbed. The methoxy species react via one of two channels, a recombination reaction with surface hydroxyls to form additional methanol at ∼350 K and a disproportionation reaction to form methanol and formaldehyde at ∼500 K. Only 20% of the methoxy species undergo the disproportionation reaction, with most of them reacting via the 350 K pathway.
A dual-effect solution for broadband piezoelectric energy harvesting
Authors: Zhao Bao , Wang Jiahua , Liang Junrui , Liao Wei-Hsin
Published: February 2020

Literature has shown that the bandwidth of a piezoelectric energy harvesting (PEH) system can be effectively broadened by introducing nonlinear mechanical dynamics. However, when connected to a practical PEH interface circuit for ac-to-dc conversion, the bandwidth improvement will be impaired because of the electrically induced damping effect. On the other hand, there is another bandwidth broadening solution, in which the resonant frequency is tunable to some extent by carrying out the phase-variable synchronized switch (PVSS) control in practical interface circuits. This Letter reports a synergistic design by combining these two mechanisms toward a dual-effect broadband PEH solution. The theoretical model of this nonlinear and electromechanically coupled system is derived. The experimental result shows that, by introducing the PVSS control to a PEH system, which is composed of a monostable piezoelectric cantilever beam and a practical synchronized switch interface circuit, its bandwidth can be broadened by 18.7%. This dual-effect solution incorporates two bandwidth broadening mechanisms toward practical broadband PEH systems.
Optical transitions for impurities in Ga2O3 as determined by photo-induced electron paramagnetic resonance spectroscopy
Authors: Bhandari Suman , Zvanut M. E.
Published: February 2020

Impurities such as Fe and Mg are intentionally incorporated into Ga2O3 to control the intrinsic n-type conductivity. This work examines the defect level of the intentional and unintentional impurities in β-Ga2O3 substrates grown for electronic applications. First, several dominant impurities, Fe3+, Mg0, and Ir4+, are identified using electron paramagnetic resonance spectroscopy. Then, by illuminating the crystals with selected wavelengths between 1500 and 300 nm, the photothreshold for excitation or quenching of each impurity is examined. Defect levels are estimated from the photothreshold after considering interdefect transitions and lattice relaxation. Thresholds for Ir4+ (2.0–2.3 eV) and Fe3+ (1.2–1.5 eV) support the reported values of the Ir3+/4+ and Fe2+/3+ defect levels, but the photothreshold of 1.6–1.9 eV observed for the quenching of neutral Mg requires further consideration.
Epitaxial growth of single tellurium atomic wires on a Cu2Sb surface alloy
Authors: Zhou Dechun , Li Heping , Si Nan , Jiang Yixuan , Huang Han , Li Hui , Niu Tianchao
Published: February 2020

One-dimensional (1D) zigzag tellurium (Te) wires on an alloyed Cu2Sb (111) surface are produced and characterized by combining molecular beam epitaxy and high-resolution scanning tunneling microscopy, respectively. These 1D Te wires with zigzag shapes exhibit a uniform width and well-defined periodicity grown in registry on a Cu2Sb (111) substrate. Density functional theory (DFT) calculations revealed a remarkable bandgap of 0.3 eV induced by spin–orbit coupling. Interestingly, the resulting Te wires became metallic on the substrate, as confirmed by scanning tunneling spectroscopy and DFT. The present study provides a platform for constructing periodic atomic wires on alloyed surfaces, which may be extended further to integrate them into circuits.
Epitaxially grown Cu2Sb-type MnGaGe films with large perpendicular magnetic anisotropy
Authors: Sun Mingling , Kubota Takahide , Ito Keita , Takahashi Shigeki , Hirayama Yoshiyuki , Sonobe Yoshiaki , Takanashi Koki
Published: February 2020

A perpendicularly magnetized film is essentially important for spintronics applications, such as spin-transfer-torque type magnetoresistive random access memories, STT-MRAMs, and large perpendicular anisotropy energy, Ku, with small saturation magnetization, Ms, is required for reducing the critical current for the STT induced magnetization switching phenomenon. In this study, an equiatomic intermetallic compound, MnGaGe, was investigated in epitaxially grown film samples. Perpendicularly magnetized films with an Ms value of about 260 emu/cm3 at 300 K were fabricated onto MgO (100) single crystal substrates. The maximum value of Ku was 8.1 × 106 erg/cm3 at room temperature. Microstructure analysis using a scanning transmission electron microscope atomically revealed the Cu2Sb type crystal structure in the film sample. First principles calculations were also carried out to discuss the electronic structure. Using the analysis of the projected density of states for 3d-orbitals, the hybridization of the 3d-orbitals was suggested as a possible factor for promoting magnetocrystalline anisotropy. The MnGaGe film with the large Ku and relatively small Ms would be potentially used for spintronics applications.
The unusual symmetry of hexafluoro-o-xylene—A microwave spectroscopy and computational study
Authors: Herbers Sven , Fritz Sean M. , Mishra Piyush , Kim Yongbin , Slipchenko Lyudmila , Zwier Timothy S.
Published: February 2020

The rotational constants and quartic centrifugal distortion coefficients of hexafluoro-o-xylene were precisely derived from the 8 GHz to 18 GHz gas phase microwave spectrum. In addition, the rotational constants of all singly substituted 13C isotopologues were determined. Instead of the intuitively expected symmetry of C2v, as in o-xylene, calculations with a variety of methods (B3LYP, CAM-B3LYP, ωB97XD, MP2, and coupled-cluster singles, doubles, and perturbative triples) predict a C2 symmetry structure in which the two CF3 groups rotate in opposite directions by about 16°. While the experimental results in this study are not capable of proving this unusual symmetry, they can support future microwave, gas phase electron diffraction or nuclear magnetic resonance studies. From the presented data, a preliminary r0 structure was determined, reproducing the experimental rotational constants with deviations of no more than 15 kHz. Analysis of the interactions between the two CF3 groups using an effective fragment potential approach identifies two major contributions to their interaction, due to exchange-repulsion and electrostatic repulsion, with electrostatic repulsion responsible for the barrier at the C2v geometry.
Giant electrocaloric response in compositional manipulated BaTiO3 relaxor–ferroelectric system
Authors: Hou Ying , Li Jiacheng , Ding Junfeng , Ye Tingting , Liang Ruihong
Published: February 2020

The compositional manipulation of the multiphase coexistence in relaxor–ferroelectrics has been reported to be an effective approach to generate the giant electrocaloric effect. In this work, we systemically investigate the temperature-dependent electrocaloric effect in BaZr0.18Ti0.82O3–BaSn0.11Ti0.89O3 relaxors, where Zr and Sn are introduced into BaTiO3 to develop the multiphase coexistence at the ferroelectric–paraelectric transition. Through the direct measurement by the heat flux sensor, a large temperature change around 4 K under an electric field of 10 MV m−1, combined with a broad temperature span (20 °C–60 °C), has been observed. For comparison, the electrocaloric properties are also indirectly deduced based on Maxwell equations and Landau–Ginzburg–Devonshire phenomenological theory, and the validity of the indirect methods in this relaxor–ferroelectric system has been discussed. This work would shed light on developing giant electrocaloric materials with a wide operating temperature range.
Multiple scattering in scanning helium microscopy
Authors: Lambrick S. M. , Vozdecký L. , Bergin M. , Halpin J. E. , MacLaren D. A. , Dastoor P. C. , Przyborski S. A. , Jardine A. P. , Ward D. J.
Published: February 2020

Using atom beams to image the surface of samples in real space is an emerging technique that delivers unique contrast from delicate samples. Here, we explore the contrast that arises from multiple scattering of helium atoms, a specific process that plays an important role in forming topographic contrast in scanning helium microscopy (SHeM) images. A test sample consisting of a series of trenches of varying depths was prepared by ion beam milling. SHeM images of shallow trenches (depth/width < 1) exhibited the established contrast associated with masking of the illuminating atom beam. The size of the masks was used to estimate the trench depths and showed good agreement with the known values. In contrast, deep trenches (depth/width > 1) exhibited an enhanced intensity. The scattered helium signal was modeled analytically and simulated numerically using Monte Carlo ray tracing. Both approaches gave excellent agreement with the experimental data and confirmed that the enhancement was due to localization of scattered helium atoms due to multiple scattering. The results were used to interpret SHeM images of a bio-technologically relevant sample with a deep porous structure, highlighting the relevance of multiple scattering in SHeM image interpretation.
Phylogenetic placement of the Australian Pharetis, gen. nov., and Spherita, gen. nov., in a revised classification of the circum-Antarctic Moriomorphini (Coleoptera : Carabidae)
Authors: Liebherr James K.
Published: February 2020

The carabid beetle tribe Moriomorphini attains a disjunct austral geographical distribution, with member taxa occupying Australia, New Zealand, New Caledonia, the Sundas, southern South America and Polynesia. The group arose in Australia, the area exhibiting the greatest generic diversity for the tribe. In this contribution, two new genera are added to the Australian fauna. Pharetis thayerae, gen. nov., sp. nov., is described from Grenvillia, New South Wales, and Spherita newtoni, gen. nov., sp. nov., is described from Avon Valley National Park, Western Australia. Their phylogenetic placement within the tribe is accomplished by parsimony analysis based on 208 morphological characters across 124 taxa, 114 in-group species and 10 outgroup taxa representing Trechini, Psydrini and Patrobini. Nearly all polytypic moriomorphine genera are represented in the analysis by at least two exemplars, allowing initial tests of generic monophyly. A revised classification is proposed for Moriomorphini, with subtribal clades related as (Amblytelina + (Moriomorphina + Tropopterina)). The Western Australian genus Spherita is placed as adelphotaxon to Sitaphe Moore, a genus restricted to tropical montane Queensland. From the phylogenetic analysis, other non-contemporaneous east–west Australian disjunctions can be inferred, as well as multiple trans-Tasman area relationships between eastern Australia and New Zealand, all proposed to be of Miocene age. Pharetis exhibits a disjunct, trans-Antarctic relationship with Tropopterus Solier, its sister-group, distributed in southern South America. Alternative vicariance-based and dispersal-based hypotheses are discussed for the origin of Tropopterus. A review of the taxonomic development of the tribe illustrates the signal importance of monotypic genera in elucidating biological diversity.
Separatists or terrorists? Jews or Nigerians?
Authors: Chiluwa Innocent , Chiluwa Isioma M.
Published: February 2020

This study adopts a discourse analytical approach to examine the contested identity of the Igbos of the southeast of Nigeria. It analyses the significance of the social and political discourses in the media and the Internet about their claim to the Jewish ancestry and as “Biafrans” rather than Nigerians. The study highlights the implications of these claims and their larger political implications for Nigeria. The study also shows that ideological construction of group identity by IPOB consistently portrays them as the victim and the marginalized. And their claim to Jewish ancestry is possibly a way of seeking foreign support.
To Thine Own Self, be True: Examining Change in Self-Reported Alcohol Measures over Time as Related to Socially Desirable Responding Bias among People with Unhealthy Alcohol Use
Authors: Schell Christina , Godinho Alexandra , Cunningham John A.
Published: February 2020

Background

Due to a conscious or unconscious desire to be perceived favorably by others, some participants may under or overexaggerate when reporting sensitive behaviors or attitudes, including those related to addictions. This socially desirable responding bias should be considered when using self-reports in predictive models since it introduces error.

Methods

A total of 1711 participants were recruited using Amazon's Mechanical Turk crowdsourcing platform for two randomized controlled trials investigating the effectiveness of brief online interventions for hazardous alcohol use. At baseline, participants completed the Balanced Inventory of Desirable Responding (BIDR). Four measures of alcohol use were collected at baseline and follow-up: number of drinks consumed in a typical week, on one occasion, consequences experienced, and amount of perceived risk of injury or illness from alcohol use.

Results

As expected, individuals scoring high on the BIDR subscales reported less alcohol use and related behaviors ( p < 0.05); however, repeating the analyses for each gender showed no difference for females asked direct questions about the frequency of their alcohol use. Mixed-effects models investigating the interaction of socially desirable responding bias over time on alcohol-related measures showed some significant differences in the amount of change reported depending on BIDR scores. Participants with higher self-deceptive enhancement scores reported less change over time in their ratings of risk of illness or injury ( p = 0.001) compared to lower-scoring participants. Likewise, high-scoring participants reported less change in the number of consequences experienced due to alcohol use over time on both BIDR subscales. Neither direct measure of alcohol use seemed affected by BIDR scores over time. A different pattern was found in males and females analyzed separately.

Conclusions

These findings suggest that researchers should consider including measures of socially desirable responding bias in longitudinal studies involving self-reported alcohol use, particularly when modeling alcohol-related measures using rating scales across time. In addition, separate gender analyses may be appropriate. Trial registration: ClinicalTrials.gov NCT03008928. Registered 30 December 2016; ClinicalTrials.gov NCT03060135. Registered 17 February 2017
Syncrip/hnRNP Q is required for activity-induced Msp300/Nesprin-1 expression and new synapse formation
Authors: Titlow Joshua , Robertson Francesca , Järvelin Aino , Ish-Horowicz David , Smith Carlas , Gratton Enrico , Davis Ilan
Published: February 2020

Memory and learning involve activity-driven expression of proteins and cytoskeletal reorganization at new synapses, requiring posttranscriptional regulation of localized mRNA a long distance from corresponding nuclei. A key factor expressed early in synapse formation is Msp300/Nesprin-1, which organizes actin filaments around the new synapse. How Msp300 expression is regulated during synaptic plasticity is poorly understood. Here, we show that activity-dependent accumulation of Msp300 in the postsynaptic compartment of theDrosophila larval neuromuscular junction is regulated by the conserved RNA binding protein Syncrip/hnRNP Q. Syncrip (Syp) binds tomsp300 transcripts and is essential for plasticity. Single-molecule imaging shows that msp300 is associated with Syp in vivo and forms ribosome-rich granules that contain the translation factor eIF4E. Elevated neural activity alters the dynamics of Syp and the number ofmsp300:Syp:eIF4E RNP granules at the synapse, suggesting that these particles facilitate translation. These results introduce Syp as an important early acting activity-dependent regulator of a plasticity gene that is strongly associated with human ataxias.
CDK1 couples proliferation with protein synthesis
Authors: Haneke Katharina , Schott Johanna , Lindner Doris , Hollensen Anne Kruse , Damgaard Christian Kroun , Mongis Cyril , Knop Michael , Palm Wilhelm , Ruggieri Alessia , Stoecklin Georg
Published: February 2020

Cell proliferation exerts a high demand on protein synthesis, yet the mechanisms coupling the two processes are not fully understood. A kinase and phosphatase screen for activators of translation, based on the formation of stress granules in human cells, revealed cell cycle–associated kinases as major candidates. CDK1 was identified as a positive regulator of global translation, and cell synchronization experiments showed that this is an extramitotic function of CDK1. Different pathways including eIF2α, 4EBP, and S6K1 signaling contribute to controlling global translation downstream of CDK1. Moreover, Ribo-Seq analysis uncovered that CDK1 exerts a particularly strong effect on the translation of 5′TOP mRNAs, which includes mRNAs encoding ribosomal proteins and several translation factors. This effect requires the 5′TOP mRNA-binding protein LARP1, concurrent to our finding that LARP1 phosphorylation is strongly dependent on CDK1. Thus, CDK1 provides a direct means to couple cell proliferation with biosynthesis of the translation machinery and the rate of protein synthesis.
Wavefront Shaping for Fast Focusing Light through Scattering Media Based on Parallel Wavefront Optimization and Superpixel Method*
Authors: Ding Yingchun , Lv Xinjing , Jia Youquan , Zhang Bin , Chen Zhaoyang , Liu Qiang
Published: February 2020

When light travels in biological tissues, it undergoes multiple scattering and forms speckles, which seriously restricts the penetration depth of optical imaging in biological tissues. With wavefront shaping method, by modulating the wavefront of incident light to compensate for the wavefront aberration, light focusing and scanning imaging through scattering media can be achieved. However, wavefront shaping must be accomplished within the speckle decorrelation time. Considering the short speckle decorrelation time of living tissues, the speed of wavefront shaping is rather essential. We propose a new iterative optimization wavefront shaping method to improve the speed of wavefront shaping in which the existing parallel optimization wavefront shaping method is improved and is combined with the superpixel method. Compared with the traditional multi-frequency parallel optimization method, the modulation rate of our method is doubled. Moreover, we combine the high frame rate amplitude modulator, i.e., the digital micromirror device (DMD), with the superpixel method to replace the traditional phase modulator (i.e., spatial light modulator), which further increases the optimization speed. In our experiment, when the number of the optical modes is 400, light focusing is achieved with only 1000 DMD superpixel masks and the enhancement factor reaches 223. Our approach provides a new path for fast light focusing through wavefront shaping.
Adsorption of Perylene on Si(111)(7 × 7)*
Authors: Guan Dandan , Wang Xinwei , Mao Hongying , Bao Shining , Jia Jin-Feng
Published: February 2020

We investigate the adsorption of organic molecular semiconductor perylene on (7 × 7) reconstructed Si(111) surface by ultraviolet photoemission spectroscopy. It is observed that seven features that derive from the organic material are located at 0.71, 2.24, 4.0, 5.9, 7.46, 8.65 and 9.95 eV in binding energy. The theoretical calculation results reveal the most stable adsorption geometry of organic molecule perylene on Si(111) (7 × 7) substrates is at the beginning of deposition.
Physical Properties of Half-Heusler Antiferromagnet MnPtSn Single Crystal*
Authors: Wang Qi , Du Qianheng , Petrovic Cedomir , Lei Hechang
Published: February 2020

We report the growth of ternary half-Heusler MnPtSn single crystals and detailed study on its structural and physical properties. MnPtSn single crystal has a larger lattice parameter than that in polycrystal and it exhibits antiferromagnetism with transition temperature T
N at about 215 K, distinctly different from the ferromagnetism of MnPtSn polycrystal. Hall resistivity measurement indicates that the dominant carriers are hole-type and the nearly temperature-independent carrier concentration reaches about 2.86 × 1022 cm−3 at 5 K. Moreover, the carrier mobility is also rather low (4.7 cm2⋅V−1s−1 at 5 K). The above results strongly suggest that the significant Mn/Sn anti-site defects, i.e., the content of Mn in MnPtSn single crystal, play a vital role on structural, magnetic and transport properties.
Modulation of heat transport in two-dimensional group-III chalcogenides
Authors: Wan Wenhui , Song Ziwei , Zhao Shan , Ge Yanfeng , Liu Yong
Published: February 2020

We systematically investigated the modulation of heat transport of experimentally accessible two-dimensional (2D) group-III chalcogenides by first-principles calculations. It was found that intrinsic thermal conductivity (κ) of chalcogenides MX (M = Ga, In; X = S, Se) were desirable for efficient heat dissipation. Meanwhile, we showed that the long-ranged harmonic and anharmonic interactions played an important role in heat transport of the chalcogenides. The difference of κ among the 2D group-III chalcogenides can be well described by the Slack model and can be mainly attributed to phonon group velocity. Based on that, we proposed three methods including strain engineering, size effect and making Janus structures to effectively modulate the κ of 2D group-III chalcogenides, with different underlying mechanisms. We found that tensile strain and rough boundary scattering could continuously decrease the κ while compressive strain could increase the κ of 2D group-III chalcogenides. On the other side, the change of κ by producing Janus structures is permanent and dependent on the structural details. These results provide guilds to modulate heat transport properties of 2D group-III chalcogenides for devices application.
Identifying the graphene d-wave superconducting symmetry by an anomalous splitting zero-bias conductance peak
Authors: Huang Chuan-Shuai , Yang Yang , Tao Y C , Wang Jun
Published: February 2020

Not until recently, was a gate-tunable, high-temperature superconducting proximity effect in graphene demonstrated experimentally. And usually in d-wave superconductor (SC) hybrid structure, ferromagnetism and spin-triplet states could result in a splitting zero-bias conductance peak (ZBCP). Herein, we theoretically present an anomalous splitting ZBCP in a graphene-based ferromagnet/Rashba spin–orbit coupling (RSOC)/insulator/d-wave SC hybrid structure. With increasing the exchange field from h/E
F = 0, the ZBCP starts to turn into a splitting one with a zero-bias conductance dip (ZBCD) sandwiched in between two subpeaks, while from h/E
F = 1, the two subpeaks and ZBCD begin to gradually shrink till the ZBCP reappears. The anomalous splitting ZBCP can be modulated by the RSOC strength, magnitude of Fermi wave vector mismatch as well as insulator barrier strength. These peculiar features are ascribed to the novel spin-triplet Andreev reflection in the context of the RSOC, characteristic by the anisotropic d-wave pair symmetry combined with the relativistic nodal fermions, which in turn can be experimentally used to directly identify not only the proximity-induced ferromagnetism and RSOC but d-wave pair symmetry in graphene. These results pave the way to a new class of tunable, high-temperature superconducting spintronic devices based on large-scale graphene.
Cross sections for (n, 2n), (n, p), (n, a) and (n, n′) reactions on hafnium isotopes around the neutron energy of 14 MeV
Authors: Li Yong , Zhou Fengqun , Song Yueli , Chang Xinyi , Ji Pengfei , Sun Xiaojun , Li Guoqiang
Published: February 2020

In view of the fact that the fast-neutron experimental cross-section data of hafnium which is an important structural material of fusion reactor are few and there are the great differences in their evaluation values, several activation cross sections of (n, 2n), (n, p), (n, a) and (n, n′) reactions on hafnium isotopes have been investigated by neutrons generated from the T(d, n)4He reaction at the K-400 Neutron Generator at China Academy of Engineering Physics (CAEP). The gamma activities of the product nuclei were measured by a high-resolution gamma-ray spectrometer with a coaxial high-purity germanium detector. The 93Nb(n, 2n)92mNb reaction was used as neutron fluence standard, these experimental cross sections of the 174Hf(n, 2n)173Hf, 176Hf(n, 2n)175Hf, 178Hf(n, α)175m+gYb, 178Hf(n, p)178gLu, 178Hf(n, p)178mLu, 180Hf(n, 2n)179m2Hf, 180Hf(n, α)177m+gYb and 180Hf(n, n′)180mHf reactions were obtained in the neutron energy range of 13.5–14.8 MeV. These measured cross sections were discussed and compared with some previous experimental results from the literature and with the evaluation data from ENDF/B-VIII.0, CENDL-3.1, JEFF-3.3 and the theoretical results by using the computer code system Talys-1.9.
Spin decoherence in inhomogeneous media
Authors: Crosse J A
Published: February 2020

A Green’s function formalism for describing the decoherence of a ‘central spin’ in inhomogeneous media is developed. By embedding the ‘central spin’ in a background medium and performing real-cavity, local-field corrections on the macroscopic fields at the location of the ‘central spin’ one can show that the Green’s function splits up into two main contributions, a contribution that is related to the bulk properties of the background medium and a contribution that is related inhomogeneities within the background medium. As an example, the coherence time of a shallowNVcenter in diamond close to a planar interface, both in the absence and presence of surface spins, is computed. It is found that the coherence time of theNVcenter increases as it moves away from the interface and, at distances greater than ≈1 nm, the interaction with the interface is negligible with the main source of decoherence coming from the interaction with the surface spins. Above ≈50 nm the interaction with the surface spins is also negligible and one recovers the bulk coherence time.
Anisotropic critical behavior of current-driven skyrmion dynamics in chiral magnets with disorder
Authors: Xiong L , Zheng B , Jin M H , Zhou N J
Published: February 2020

The dynamic pinning effects are significant in manipulating skymions in chiral magnetic materials with quenched disorder. Through numerical simulations of the non-stationary current-driven dynamics of skyrmions with the Landau–Lifshitz–Gilbert equation, the critical current, static and dynamic critical exponents of the depenning phase transition are accurately determined for both adiabatic and non-adiabatic spin-transfer torques and with different strengths of disorder, based on the dynamic scaling behavior far from stationary. We find that the threshold current is insensitive to a small non-adiabatic coefficient of the spin-transfer torque, but dramatically reduced for a large one. The critical exponents indicate that the critical dynamic behavior is robust for different spin-transfer torques in the perpendicular component of the Hall motion, while exhibits a weak universality class in the direction of the driving current. The anisotropic behavior around the depinning phase transition provides a quantitative analysis of the drive-dependent skyrmion Hall effect in experiments. Further, the theoretical analysis using the Thiele’s approach is presented, and the critical current and the static exponents support the simulation results.
Plasticity to drought and ecotypic differentiation in populations of a crop wild relative
Authors: Matesanz S , Ramos-Muñoz M , Moncalvillo B , Rubio Teso M L , García de Dionisio S L , Romero J , Iriondo J M
Published: February 2020

Populations of widely distributed species often exhibit geographic variation in functional traits in response to environmental heterogeneity. Such trait variation may be the result of different adaptive mechanisms, including genetically based differentiation, phenotypic plasticity or a combination of both. Disentangling the genetic and environmental components of trait variation may be particularly interesting in crop wild relatives, since they may provide unique reservoirs of genetic diversity for crop improvement. In this study, we assessed ecotypic differentiation and patterns of plasticity to drought in populations of Lupinus angustifolius, a Mediterranean crop wild relative, from two climatically distinct regions in the Iberian Peninsula. Using an outdoor common garden, we compared phenotypic responses of inbred maternal families to two ecologically meaningful water availability treatments (drought and high-moisture). We measured 18 different functional traits related to growth, morphology, phenology and reproduction. Plants in the drought treatment grew less, had lower leaf chlorophyll content and photochemical efficiency, but also reproduced faster, produced larger seeds and altered leaflet morphology through increased leaflet thickness, higher leaflet dry matter content and lower specific leaf area. We also found significant differences between regions that likely reflect adaptation to climatically distinct environments, with populations from the south showing a faster onset of reproduction, higher leaf thickness and higher seed size, consistent with the drier conditions experienced in southern sites. Plasticity to drought was in most cases in the same direction as quantitative genetic differentiation (i.e. cogradient variation), providing evidence of the adaptive value of the plastic change. Our results show that both genetic differentiation and plasticity can generate adaptive phenotypic variation in L. angustifolius, and help to identify potentially valuable genetic resources to incorporate into breeding programmes.
GeneSwitches: ordering gene expression and functional events in single-cell experiments
Authors: Cao Elaine Y , Ouyang John F , Rackham Owen J L
Published: February 2020

Emerging single-cell RNA-sequencing data technologies has made it possible to capture and assess the gene expression of individual cells. Based on the similarity of gene expression profiles, many tools have been developed to generate an in silico ordering of cells in the form of pseudo-time trajectories. However, these tools do not provide a means to find the ordering of critical gene expression changes over pseudo-time. We present GeneSwitches, a tool that takes any single-cell pseudo-time trajectory and determines the precise order of gene expression and functional-event changes over time. GeneSwitches uses a statistical framework based on logistic regression to identify the order in which genes are either switched on or off along pseudo-time. With this information, users can identify the order in which surface markers appear, investigate how functional ontologies are gained or lost over time and compare the ordering of switching genes from two related pseudo-temporal processes.

Availability

GeneSwitches is available at https://geneswitches.ddnetbio.com.

Supplementary information

Supplementary data are available at Bioinformatics online.
White matter basis for the hub-and-spoke semantic representation: evidence from semantic dementia
Authors: Chen Yan , Huang Lin , Chen Keliang , Ding Junhua , Zhang Yumei , Yang Qing , Lv Yingru , Han Zaizhu , Guo Qihao
Published: February 2020

The hub-and-spoke semantic representation theory posits that semantic knowledge is processed in a neural network, which contains an amodal hub, the sensorimotor modality-specific regions, and the connections between them. The exact neural basis of the hub, regions and connectivity remains unclear. Semantic dementia could be an ideal lesion model to construct the semantic network as this disease presents both amodal and modality-specific semantic processing (e.g. colour) deficits. The goal of the present study was to identify, using an unbiased data-driven approach, the semantic hub and its general and modality-specific semantic white matter connections by investigating the relationship between the lesion degree of the network and the severity of semantic deficits in 33 patients with semantic dementia. Data of diffusion-weighted imaging and behavioural performance in processing knowledge of general semantic and six sensorimotor modalities (i.e. object form, colour, motion, sound, manipulation and function) were collected from each subject. Specifically, to identify the semantic hub, we mapped the white matter nodal degree value (a graph theoretical index) of the 90 regions in the automated anatomical labelling atlas with the general semantic abilities of the patients. Of the regions, only the left fusiform gyrus was identified as the hub because its structural connectivity strength (i.e. nodal degree value) could significantly predict the general semantic processing of the patients. To identify the general and modality-specific semantic connections of the semantic hub, we separately correlated the white matter integrity values of each tract connected with the left fusiform gyrus, with the performance for general semantic processing and each of six semantic modality processing. The results showed that the hub region worked in concert with nine other regions in the semantic memory network for general semantic processing. Moreover, the connection between the hub and the left calcarine was associated with colour-specific semantic processing. The observed effects could not be accounted for by potential confounding variables (e.g. total grey matter volume, regional grey matter volume and performance on non-semantic control tasks). Our findings refine the neuroanatomical structure of the semantic network and underline the critical role of the left fusiform gyrus and its connectivity in the network.
High miR-133a levels in the circulation anticipates presentation of clinical events in familial hypercholesterolaemia patients
Authors: Escate Rafael , Padró Teresa , Suades Rosa , Camino Sandra , Muñiz Ovidio , Diaz-Diaz Jose Luis , Sionis Alessandro , Mata Pedro , Badimon Lina
Published: February 2020

Aims

Presentation of acute events in patients with atherosclerosis remains unpredictable even after controlling for classical risk factors. MicroRNAs (miRNAs) measured in liquid biopsies could be good candidate biomarkers to improve risk prediction. Here, we hypothesized that miRNAs could predict atherosclerotic plaque progression and clinical event presentation in familial hypercholesterolaemia (FH) patients.

Methods and results

Circulating miRNAs (plasma, exosomes, and microvesicles) were investigated by TaqMan Array and RT-qPCR assays. Patients with genetic diagnosis of FH and healthy relatives from the SAFEHEART cohort were included. A differential signature of 10 miRNA was obtained by comparing two extreme phenotypes consisting of FH patients suffering a cardiovascular event (CVE) within a 8-year follow-up period (FH-CVE, N = 42) and non-FH hypercholesterolaemic relatives from the same cohort, matched for age and treatment, without CVE during the same period (nFH-nCVE, N = 30). The validation studies included two independent groups of patients with FH background (discovery group, N = 89, validation group N = 196), developing a future CVE (FH-CVE) or not (FH-nCVE) within the same time period of follow-up. Of the 10 miRNAs initially selected, miR-133a was significantly higher in FH-CVE than in FH-nCVE patients. Receiver operating characteristic analysis confirmed miR-133a as the best microRNA for predicting CVE in FH patients (0.76 ± 0.054; P < 0.001). Furthermore, Kaplan–Meier and COX analysis showed that high plasma miR-133a levels associated to the higher risk of presenting a CVE within the next 8 years (hazard ratio 3.89, 95% confidence interval 1.88–8.07; P < 0.001). In silico analysis of curate biological interactions related miR-133a with target genes involved in regulation of the cell-membrane lipid-receptor LRP6 and inflammatory cytokines (CXCL8, IL6, and TNF). These predictions were experimentally proven in human macrophages and endothelial cells transfected with agomiR-133a.

Conclusion

Elevated levels of miR-133a in the circulation anticipate those FH patients that are going to present a clinical CVE within the next 2 years (average). Mechanistically, miR-133a is directly related with lipid- and inflammatory signalling in key cells for atherosclerosis progression.
Preoperative renal malperfusion is an independent predictor for acute kidney injury and operative death but not associated with late mortality after surgery for acute type A aortic dissection
Authors: Nishigawa Kosaku , Fukui Toshihiro , Uemura Kohei , Takanashi Shuichiro , Shimokawa Tomoki
Published: February 2020

OBJECTIVES

This study was aimed to investigate the impact of preoperative renal malperfusion on early and late outcomes after surgery for acute type A aortic dissection (AAAD).

METHODS

Of 915 patients who underwent surgery for AAAD between September 2004 and September 2017, we enrolled 534 patients whose preoperative enhanced computed tomography images were retrospectively available in this study. Exclusion criteria were single kidney (n = 3) and dialysis-dependent preoperatively (n = 12). We compared early and late outcomes between patients who had preoperative renal malperfusion (n = 64) and those who did not have renal malperfusion (n = 470).

RESULTS

The incidence of postoperative acute kidney injury, defined using the Kidney Disease: Improving Global Outcomes criteria, was higher in the renal malperfusion group than in the no renal malperfusion group (76.6% vs 39.4%; P < 0.001). Similarly, operative death was more frequently seen in the renal malperfusion group (12.5% vs 3.8%; P = 0.003). Multivariate analyses showed that renal malperfusion was the independent predictor for postoperative acute kidney injury [odds ratio 4.32, 95% confidence interval (CI) 2.25–8.67; P < 0.001] and operative death (odds ratio 3.08, 95% CI 1.02–8.86; P = 0.046). The median follow-up period in the hospital survivors was 3.3 years (interquartile range 2.1–6.7 years). The cumulative survival rate at 8 years was similar between the groups (74.6% in the renal malperfusion group and 76.0% in the no renal malperfusion group; P = 0.349).

CONCLUSIONS

Preoperative renal malperfusion is an independent predictor for postoperative acute kidney injury and operative death but not associated with late mortality after surgery for acute type A aortic dissection.
The Impact of Obstructive Sleep Apnea on Balance, Gait, and Falls Risk: A Narrative Review of the Literature
Authors: Stevens David , Jackson Brianna , Carberry Jayne , McLoughlin James , Barr Chris , Mukherjee Sutapa , Oh Aaron , McEvoy R Doug , Crotty Maria , Vakulin Andrew
Published: February 2020

Falls-related hospitalization and injury rates are steadily increasing globally due to a growth in the aging population, and the associated health problems that increase risk of falls. One such associated health problem is sleep disturbances and disorders. Recent cohort studies have shown that subjectively reported poor quality sleep is associated with an increased risk of falls. Obstructive sleep apnea (OSA) is a common sleep disorder characterized by the repetitive reductions, or cessation, of airflow. Some studies have shown that OSA impairs posture/balance and gait with nocturnal hypoxemia the likely main cause. Emerging evidence suggests that treating OSA by continuous positive airway pressure (CPAP) can improve gait, but no studies to date have examined the effect of CPAP on posture/balance. The overall control of balance relies on a complex interaction between several physiological functions including vestibular, muscle, visual, and cognitive functions. We postulate that OSA impacts balance by affecting these different systems to various degrees, with the nocturnal hypoxic burden likely playing an important role. Importantly, these impairments in balance/posture and possible falls risk may be alleviated by OSA treatment. Larger mechanistic studies are needed to properly elucidate how OSA affects falls risk and future large-scale randomized control trials are needed to determine the effectiveness of OSA treatment in reducing the risk of falls.
Green technologies and firms’ market value: a micro-econometric analysis of European firms
Authors: Colombelli Alessandra , Ghisetti Claudia , Quatraro Francesco
Published: February 2020

This paper investigates the impact of the generation of green (environmental) technologies on the market value (MV) of a sample of listed companies. The analysis is grounded on the combination of two different theoretical approaches, that is the one focusing on the relationship between MV and innovation and the one pertaining to the economic effects of eco-innovation. Environmental regulation, based on the regulatory push–pull effect, induces firms to cope with more stringent rules through innovation efforts, and this eventually leads to the emergence of new markets for the suppliers of green technologies (GTs). Our main hypothesis is that firms able to generate GTs can be expected to show better stock market performances in this framework, because of the prospects of regulation-driven profitability gains. The empirical analysis has been carried out on a sample of listed firms from France, Germany, Italy, the Netherlands, and the UK observed over the 1985–2011 time span, and it is based on the implementation of the most recent version of the MV equation, corrected for selection bias. Results are consistent with those of previous literature and highlight the positive impact of innovation on MV. When narrowing the focus to firms operating in sectors with a high propensity to generate GTs, we have found that the stringency of the environmental regulatory framework also yields a positive a significant impact, as does the stock of GTs vis-à-vis non-GTs. Moreover, environmental regulatory framework positively moderates the positive effect of the stock of GTs. Lastly, the quality of firms’ own knowledge stocks is also found to positively influence firms’ MV.
Temporal recalibration for improving prognostic model development and risk predictions in settings where survival is improving over time
Authors: Booth Sarah , Riley Richard D , Ensor Joie , Lambert Paul C , Rutherford Mark J
Published: February 2020

Background

Prognostic models are typically developed in studies covering long time periods. However, if more recent years have seen improvements in survival, then using the full dataset may lead to out-of-date survival predictions. Period analysis addresses this by developing the model in a subset of the data from a recent time window, but results in a reduction of sample size.

Methods

We propose a new approach, called temporal recalibration, to combine the advantages of period analysis and full cohort analysis. This approach develops a model in the entire dataset and then recalibrates the baseline survival using a period analysis sample. The approaches are demonstrated utilizing a prognostic model in colon cancer built using both Cox proportional hazards and flexible parametric survival models with data from 1996–2005 from the Surveillance, Epidemiology, and End Results (SEER) Program database. Comparison of model predictions with observed survival estimates were made for new patients subsequently diagnosed in 2006 and followed-up until 2015.

Results

Period analysis and temporal recalibration provided more up-to-date survival predictions that more closely matched observed survival in subsequent data than the standard full cohort models. In addition, temporal recalibration provided more precise estimates of predictor effects.

Conclusion

Prognostic models are typically developed using a full cohort analysis that can result in out-of-date long-term survival estimates when survival has improved in recent years. Temporal recalibration is a simple method to address this, which can be used when developing and updating prognostic models to ensure survival predictions are more closely calibrated with the observed survival of individuals diagnosed subsequently.