bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic field and prominences of the young, solar-like, ultra-rapid rotator V530 Persei
Authors: Cang T.-Q. , Petit P. , Donati J.-F. , Folsom C. P. , Jardine M. , Villarreal D’Angelo C. , Vidotto A. A. , Marsden S. C. , Gallet F. , Zaire B.
Published: September 2020

Context. Young solar analogs reaching the main sequence experience very strong magnetic activity, generating angular momentum losses through wind and mass ejections.

Aims. We investigate signatures of magnetic fields and activity at the surface and in the prominence system of the ultra-rapid rotator V530 Per, a G-type solar-like member of the young open cluster α Persei. This object has a rotation period that is shorter than all stars with available magnetic maps.

Methods. With a time-series of spectropolarimetric observations gathered with ESPaDOnS over two nights on the Canada-France-Hawaii Telescope, we reconstructed the surface brightness and large-scale magnetic field of V530 Per using the Zeeman-Doppler imaging method, assuming an oblate stellar surface. We also estimated the short term evolution of the brightness distribution through latitudinal differential rotation. Using the same data set, we finally mapped the spatial distribution of prominences through tomography of the Hα emission.

Results. The brightness map is dominated by a large, dark spot near the pole, accompanied by a complex distribution of bright and dark features at lower latitudes. Taking the brightness map into account, the magnetic field map is reconstructed as well. Most of the large-scale magnetic field energy is stored in the toroidal field component. The main radial field structure is a positive region of about 500 G, at the location of the dark polar spot. The brightness map of V530 Per is sheared by solar-like differential rotation, with roughly a solar value for the difference in rotation rate between the pole and equator. It is important to note that Hα is observed in emission and it is mostly modulated by the stellar rotation period over one night. The prominence system is organized in a ring at the approximate location of the corotation radius, and displays significant evolution between the two observing nights.

Conclusions. V530 Per is the first example of a solar-type star to have its surface magnetic field and prominences mapped together, which will bring important observational constraints to better understand the role of slingshot prominences in the angular momentum evolution of the most active stars.
Kein Grund zur Panik – Angelman-Syndrom: Umgang mit seltenen Diagnosen
Authors: Willert Lisa
Published: September 2020

„Angelman-Syndrom? Hat das Kind Flügel?“ Das waren Lisa Willerts erste Gedanken, als sie mit dem ihr unbekannten Krankheitsbild in Berührung kam. In ihrem Artikel gibt sie Tipps, wie man sich seltenen Diagnosen nähern kann.
Coronavirus (COVID-19), Coagulation, and Exercise: Interactions That May Influence Health Outcomes
Authors: Zadow Emma Kate , Wundersitz Daniel William Taylor , Hughes Diane Louise , Adams Murray John , Kingsley Michael Ian Charles , Blacklock Hilary Anne , Wu Sam Shi Xuan , Benson Amanda Clare , Dutheil Frédéric , Gordon Brett Ashley
Published: September 2020

The proinflammatory cytokine storm associated with coronavirus disease 2019 (COVID-19) negatively affects the hematological system, leading to coagulation activation and endothelial dysfunction and thereby increasing the risk of venous and arterial thrombosis. Coagulopathy has been reported as associated with mortality in people with COVID-19 and is partially reflected by enhanced D-dimer levels. Poor vascular health, which is associated with the cardiometabolic health conditions frequently reported in people with severer forms of COVID-19, might exacerbate the risk of coagulopathy and mortality. Sedentary lifestyles might also contribute to the development of coagulopathy, and physical activity participation has been inherently lowered due to at-home regulations established to slow the spread of this highly infectious disease. It is possible that COVID-19, coagulation, and reduced physical activity may contribute to generate a “perfect storm,” where each fuels the other and potentially increases mortality risk. Several pharmaceutical agents are being explored to treat COVID-19, but potential negative consequences are associated with their use. Exercise is known to mitigate many of the identified side effects from the pharmaceutical agents being trialled but has not yet been considered as part of management for COVID-19. From the limited available evidence in people with cardiometabolic health conditions, low- to moderate-intensity exercise might have the potential to positively influence biochemical markers of coagulopathy, whereas high-intensity exercise is likely to increase thrombotic risk. Therefore, low- to moderate-intensity exercise could be an adjuvant therapy for people with mild-to-moderate COVID-19 and reduce the risk of developing severe symptoms of illness that are associated with enhanced mortality.
Drift velocity measurement in gas electron multiplier detectors for application in a time projection chamber polarimeter
Authors: Kushwah Rakhee , Vatedka Radhakrishna , Vadodariya Koushal
Published: September 2020

Drift velocity of electrons is an important parameter when signal formation is considered in detectors. In micro-pattern gas detectors such as the gas electron multiplier (GEM), the drift velocity is affected by non-uniform electric field configurations. In the context of x-ray polarimetric application of GEM, where the time projection chamber (TPC) configuration is used, the drift velocity plays an important role in forming time binned images. The accuracy of these images governs the information on polarization of incident photons. The work presented here proposes an experimental method to determine the drift velocity of electrons in such a gas detector. The gas under study is Ne/DME (50/50). The experimental setup comprising a single GEM is similar to the TPC polarimeter configuration. The effect of gas pressure and electric field on drift velocity is presented in the work. It is encouraging to find that the experimental values match well with the simulated values. We briefly discuss the effect of variation in the drift velocity on the performance parameters of the polarimeter. The implementation of this method in any future TPC polarimeter is also explored.
Suppression of Rijke tube oscillations by delay coupling
Authors: Hyodo H. , Iwasaki M. , Biwa T.
Published: September 2020

This study experimentally analyzes the cessation of self-sustained periodic oscillations of gas columns in delay-coupled Rijke tube oscillators. The Rijke tube oscillator comprised an open-ended resonance tube with a Bunsen burner inserted into it. Delay coupling was introduced using acoustic waves propagating through a gas-filled tube with both ends connected to the resonance tubes. Two coupling methods, single- and double-tube coupling, were tested for comparison. A significant reduction in the acoustic amplitude was observed with relatively narrow tubes in double-tube coupling when the tube lengths were equal to half the wavelength and one wavelength of the acoustic waves of the uncoupled oscillator. The experimental results were analyzed using the theoretical model of the delay-coupled Rijke tube oscillators, whose coupling strength varied with the delay time. The present results would be useful in establishing a simple method for suppressing unwanted acoustic oscillations observed in various combustors.
Explicitly correlated coupled cluster method for accurate treatment of open-shell molecules with hundreds of atoms
Authors: Kumar Ashutosh , Neese Frank , Valeev Edward F.
Published: September 2020

We present a near-linear scaling formulation of the explicitly correlated coupled-cluster singles and doubles with the perturbative triples method [CCSD(T)F12¯] for high-spin states of open-shell species. The approach is based on the conventional open-shell CCSD formalism [M. Saitow et al., J. Chem. Phys. 146, 164105 (2017)] utilizing the domain local pair-natural orbitals (DLPNO) framework. The use of spin-independent set of pair-natural orbitals ensures exact agreement with the closed-shell formalism reported previously, with only marginally impact on the cost (e.g., the open-shell formalism is only 1.5 times slower than the closed-shell counterpart for the C160H322 n-alkane, with the measured size complexity of ≈1.2). Evaluation of coupled-cluster energies near the complete-basis-set (CBS) limit for open-shell systems with more than 550 atoms and 5000 basis functions is feasible on a single multi-core computer in less than 3 days. The aug-cc-pVTZ DLPNO-CCSD(T)F12¯ contribution to the heat of formation for the 50 largest molecules among the 348 core combustion species benchmark set [J. Klippenstein et al., J. Phys. Chem. A 121, 6580–6602 (2017)] had root-mean-square deviation (RMSD) from the extrapolated CBS CCSD(T) reference values of 0.3 kcal/mol. For a more challenging set of 50 reactions involving small closed- and open-shell molecules [G. Knizia et al., J. Chem. Phys. 130, 054104 (2009)], the aug-cc-pVQ(+d)Z DLPNO-CCSD(T)F12¯ yielded a RMSD of ∼0.4 kcal/mol with respect to the CBS CCSD(T) estimate.
An entropy-maximization approach to automated training set generation for interatomic potentials
Authors: Karabin Mariia , Perez Danny
Published: September 2020

Machine learning-based interatomic potentials are currently garnering a lot of attention as they strive to achieve the accuracy of electronic structure methods at the computational cost of empirical potentials. Given their generic functional forms, the transferability of these potentials is highly dependent on the quality of the training set, the generation of which can be highly labor-intensive. Good training sets should at once contain a very diverse set of configurations while avoiding redundancies that incur cost without providing benefits. We formalize these requirements in a local entropy-maximization framework and propose an automated sampling scheme to sample from this objective function. We show that this approach generates much more diverse training sets than unbiased sampling and is competitive with hand-crafted training sets.
Synthesis and characterization of bulk Si–Ti nanocomposite and comparisons of approaches for enhanced thermoelectric properties in nanocomposites composed of Si and various metal silicides
Authors: Tanusilp Sora-at , Ohishi Yuji , Muta Hiroaki , Kurosaki Ken
Published: September 2020

Si-based materials are considered as promising candidates for thermoelectric materials, owing to several advantages such as non-toxicity, abundance, and high stability. One of the strategies to develop high-efficiency Si-based thermoelectric materials with enhanced figure of merit zT is increasing the μH/κlat ratio, where μH and κlat are the Hall mobility and lattice thermal conductivity, respectively. In the present study, we synthesize a bulk Si–Ti nanocomposite composed of Si and Ti silicide by a combined method of melt-spinning and spark plasma sintering and examine the thermoelectric properties. The obtained results are compared with the data for Si–V and Si–Ni nanocomposites reported previously by the authors’ group. In the comparison, we focus on (1) size and distribution of the precipitates, (2) the interface between Si and the precipitates, and (3) volume fraction of the precipitates; and investigate the effects of these three factors on keeping high μH and reduction of κlat. Based on the comparison, it is revealed that the uniform distribution of the precipitates and the coherent interface between Si and metal silicide lead to large μH/κlat ratio and thus enhanced zT in the nanocomposites composed of Si and metal silicides.
Improvement of sound absorption and insulation using a double-layer metamaterial
Authors: Zheng Qiquan , Zhao Honggang , Wang Yang , Cao Junhui , Wen Jihong
Published: September 2020

Improvement of sound absorption and insulation using a double-layer metamaterial (DM) in the acoustic free field is proposed in the present paper. The front layer of the DM is composed of a flexible micro-perforated plate with periodic local resonators, the backing layer is a flexible plate attached with periodic local resonators too, and an air gap exists between the double plates. Good agreement is gained between the results of the theoretical prediction and finite element simulation for the DM and the original double-layer plate (DP) while considering the vibroacoustic coupling between the sound excitation and the plates. Both theoretical and simulation results verify that the local resonators can improve the sound absorption and insulation of the DP. The underlying mechanism of the DM is investigated using the acoustic impedance and displacement pattern. Filling the gap with the porous material can further improve the sound absorption and insulation of the DM. Finally, the influences of the number and additional mass ratio of local resonators on the acoustic performance of the DM are investigated, and the practical realization of the DM is verified. The present design shows great potential for practical noise reduction in the free field.
Tuning the charge transfer character of the multiexciton state in singlet fission
Authors: Chen Michelle , Shin Jae Yoon , Young Ryan M. , Wasielewski Michael R.
Published: September 2020

Intramolecular singlet fission (SF) produces the multiexciton correlated triplet pair state, (T1T1), prior to the formation of free triplet excitons. The nature of the multiexciton state is complex, as generation of the (T1T1) state may involve a charge transfer (CT) intermediate and has been shown to have both mixed electronic and spin characters. According to transient absorption spectroscopy, a linear terrylene-3,4:11,12-bis(dicarboximide) dimer (TDI2) exhibits solvent-dependent excited-state dynamics. As solvent polarity increases from 1,2,4-trichlorobenzene (ε = 2.2) to chlorobenzene (ε = 5.6) to 1,2-dichlorobenzene (ε = 9.9), the SF rate in TDI2 increases and the multiexciton state, which can be thought of as a linear combination of the 1(S1S0), CT, and (T1T1) states, gains more CT character. Eventually, the CT state becomes a trap state as indicated by symmetry-breaking charge separation in TDI2 in pyridine (ε = 12.3). The dielectric environment influences not only the SF rate and the relative contributions of the 1(S1S0), CT, and (T1T1) states to the overall multiexciton state but also the rate at which the state mixing evolves, with faster dynamics in higher polarity solvents. More importantly, the tunability and presence of strong CT character in the multiexciton state have implications for SF applications since they often rely on electron transfer from the free triplet excitons. This enhanced CT character in the (T1T1) state may assist with two-electron transfer directly from the (T1T1) state, allowing for facile extraction of charges in intramolecular SF systems whose (T1T1) states do not always efficiently dissociate to two triplet excitons.
Pressure statistics of gas nuclei in homogeneous isotropic turbulence with an application to cavitation inception
Authors: Bappy Mehedi H. , Carrica Pablo M. , Vela-Martín Alberto , Freire Livia S. , Buscaglia Gustavo C.
Published: September 2020

The behavior of the pressure along the trajectories of finite-sized nuclei in isotropic homogeneous turbulence is investigated using direct numerical simulations at Reλ = 150. The trajectories of nuclei of different sizes are computed by solving a modified Maxey–Riley equation under different buoyancy conditions. Results show that larger nuclei are more attracted to the vortex cores and spend more time at low-pressure regions than smaller nuclei. The average frequency of pressure fluctuations toward negative values also increases with size. These effects level off as the Stokes number becomes greater than 1. Buoyancy, characterized by the terminal velocity w, counteracts the attraction force toward vortex cores while simultaneously imposing an average vertical drift between the nuclei and the fluid. Computational results indicate that weak vortices, associated with moderately low pressures, lose their ability to capture finite-sized nuclei if w ≥ u′. The attraction exerted by the strongest vortices on the largest of the considered nuclei, on the other hand, can only be overcome by buoyancy if w ≥ 8u′. The quantitative results of this study are shown to have a significant impact on modeling cavitation inception in water. For this purpose, the Rayleigh–Plesset equation is solved along the nuclei trajectories with realistic sizes and turbulence intensities. The simulations predict cavitation inception at mean pressures several kPa above vapor pressure.
Spectroscopic identification of the •SSNO isomers
Authors: Wang Lina , Wu Zhuang , Lu Bo , Eckhardt André K. , Schreiner Peter R. , Trabelsi Tarek , Francisco Joseph S. , Yao Qian , Xie Changjian , Guo Hua , Zeng Xiaoqing
Published: September 2020

Elusive [S, S, N, O] isomers including the perthiyl radical •SSNO are S/N hybrid species in the complex bioinorganic chemistry of signaling molecules H2S and •NO. By mixing thermally generated disulfur (S2) with •NO in the gas phase, •SSNO was generated and subsequently isolated in cryogenic Ar- and N2-matrices at 10.0 K and 15.0 K, respectively. Upon irradiation with a 266 nm laser, •SSNO isomerizes to novel sulfinyl radicals cis-NSSO• and trans-NSSO• as well as thiyl radicals cis-OSNS• and trans-OSNS•, which have been characterized by combining matrix-isolation IR (15N-labeling) and UV/Vis spectroscopy and quantum chemical calculations at the CCSD(T)-F12/cc-pVTZ-F12 level of theory. The photo-induced reversible interconversion between NSSO• and OSNS• has also been observed.
Heat transfer of a hybrid nanofluid past a circular cylinder in the presence of thermal radiation and viscous dissipation
Authors: Roy Nepal Chandra , Saha Litan Kumar , Sheikholeslami Mohsen
Published: September 2020

The effects of thermal radiation and viscous dissipation on the flow and heat transfer of a hybrid nanofluid (Cu–Al2O3/water) past a circular cylinder are investigated for both assisting and opposing flows. The numerical results reveal that the flow and energy fields adjacent to the rear stagnation point are strongly affected by the opposing flow rather than the assisting flow. For the assisting flow, the size of the vortex increases for the higher volume fraction of Cu nanoparticles and Reynolds number, but it decreases with an increase in the Eckert number, conduction–radiation parameter, surface temperature parameter, and Grashof number. In the case of the opposing flow, the converse scenario is observed for all parameters except the Eckert number. For a certain set of parameters, the size of the vortex for the assisting flow is always smaller than that for the opposing flow. In general, the heat transfer for the assisting flow is stronger than that for the opposing flow. For both types of flows, the Nusselt number significantly increases owing to the increase in the volume fraction of Cu nanoparticles and Reynolds number; however, it diminishes for the higher values of the Eckert number, conduction–radiation parameter, and surface temperature parameter. It is remarkable that the Nusselt number for the Cu–Al2O3/water hybrid nanofluid is found to be higher than that for the Al2O3/water nanofluid.
Stereodynamics of rotationally inelastic scattering in cold He + HD collisions
Authors: Morita Masato , Balakrishnan Naduvalath
Published: September 2020

Stereodynamics of cold collisions has become a fertile ground for sensitive probe of molecular collisions and control of the collision outcome. A benchmark system for stereodynamic control of rotational transition is He + HD. This system was recently probed experimentally by Perreault et al. by examining quenching from j = 2 to j′ = 0 state in the v = 1 vibrational manifold of HD. Here, through explicit quantum scattering calculations on a highly accurate ab initio interaction potential for He + H2, we reveal how a combination of two shape resonances arising from l = 1 and l = 2 partial waves controls the stereodynamic outcome rather than a single l = 2 partial wave attributed in the experiment. Furthermore, for collision energies below 0.5 cm−1, it is shown that stereodynamic preference for the integral cross section follows a simple universal trend.
Transmission of airborne virus through sneezed and coughed droplets
Authors: Das Santosh K. , Alam Jan-e , Plumari Salvatore , Greco Vincenzo
Published: September 2020

The spread of COVID19 through droplets ejected by infected individuals during sneezing and coughing has been considered a matter of key concern. Therefore, a quantitative understanding of the propagation of droplets containing the virus assumes immense importance. Here, we investigate the evolution of droplets in space and time under varying external conditions of temperature, humidity, and wind flow by using laws of statistical and fluid mechanics. The effects of drag, diffusion, and gravity on droplets of different sizes and ejection velocities have been considered during their motion in air. In still air, we found that bigger droplets traverse a larger distance, but smaller droplets remain suspended in air for a longer time. Therefore, in still air, the horizontal distance that a healthy individual should maintain from an infected one is based on the bigger droplets, but the time interval to be maintained is based on the smaller droplets. We show that in places with wind flow, the lighter droplets travel a larger distance and remain suspended in air for a longer time. Therefore, we conclude that both temporal and geometric distance that a healthy individual should maintain from an infected one is based on the smaller droplets under flowing air, which makes the use of a mask mandatory to prevent the virus. Maintenance of only stationary separation between healthy and infected individuals is not substantiated. The quantitative results obtained here will be useful to devise strategies for preventing the spread of other types of droplets containing microorganisms.
Experimental investigation on pulsating pressure of a cone-cylinder-hemisphere model under different flow velocities
Authors: Miao Xuhong , Li Yuhui , Pang Fuzhen , Xiao Jingping , Jia Di
Published: September 2020

This paper presents the results of wall pulsating pressure experiments on a cone-cylinder-hemisphere model with lengths of 95 cm and maximum diameters of 20 cm under conditions of different flow velocities. By comparative analysis of experimental data, it has been found that the pulsating pressure on the wall surface of the flow-induced structure continues to rise as the flow velocity increases. It was also found that the pulsating pressure value of the shoulder and stern of the cone-cylinder-hemisphere structure is larger than in other positions. Additionally, the reliability and accuracy of the test results are verified by comparing the measured results with numerical simulation, and the characteristics and rules of the pulsating pressure of the flow-induced structure are analyzed. The pulsating pressure level is higher at the highest point and decays rapidly within 500 Hz; then, the decay rate slows down, and the pulsating pressure gradually decreases with frequency. Underwater vehicles usually adopt the form of a cone-cylindrical-hemisphere. Therefore, studying the pulsating pressure of a cone-cylinder-hemisphere structure is of great significance to the research of pulsating pressure and flow-induced noise of underwater vehicles.
CHD7 and Runx1 interaction provides a braking mechanism for hematopoietic differentiation
Authors: Hsu Jingmei , Huang Hsuan-Ting , Lee Chung-Tsai , Choudhuri Avik , Wilson Nicola K. , Abraham Brian J. , Moignard Victoria , Kucinski Iwo , Yu Shuqian , Hyde R. Katherine , Tober Joanna , Cai Xiongwei , Li Yan , Guo Yalin , Yang Song , Superdock Michael , Trompouki Eirini , Calero-Nieto Fernando J. , Ghamari Alireza , Jiang Jing , Gao Peng , Gao Long , Nguyen Vy , Robertson Anne L. , Durand Ellen M. , Kathrein Katie L. , Aifantis Iannis , Gerber Scott A. , Tong Wei , Tan Kai , Cantor Alan B. , Zhou Yi , Liu P. Paul , Young Richard A. , Göttgens Berthold , Speck Nancy A. , Zon Leonard I.
Published: September 2020

Significance

Hematopoiesis involves the control of gene expression that regulates the processes of proliferation and differentiation. We found that the chromatin remodeler CHD7 controls the differentiation process. Knockdown or knockout of CHD7 leads to enhanced hematopoietic differentiation in zebrafish and mice, suggesting that CHD7 acts as a brake on gene expression associated with terminally differentiated blood cells.
Secondary structure of the mRNA encoding listeriolysin O is essential to establish the replicative niche of
L. monocytogenes
Authors: Peterson Bret N. , Portman Jonathan L. , Feng Ying , Wang Jeffrey , Portnoy Daniel A.
Published: September 2020

Significance

Intracellular pathogens utilize specialized mechanisms for replicating within host cells while minimizing cytotoxicity. Misregulation of bacterial virulence factors that are responsible for infection can cause host cell death and the consequent loss of virulence. The results presented here reveal that the translation of a cytolysin that is responsible for host infection is reduced during bacterial growth, due to the formation of an mRNA secondary structure that results in translational inhibition. The coding domain that occludes the ribosome binding site regulates the synthesis and activity of the cytolysin inside the host cytosol, highlighting multiple levels of LLO control from this domain. These findings provide insight into how expression of a virulence factor can be translationally regulated within alternate host cellular compartments.
Most invasive species largely conserve their climatic niche
Authors: Liu Chunlong , Wolter Christian , Xian Weiwei , Jeschke Jonathan M.
Published: September 2020

Significance

There has been a widespread debate whether the ecological niche of species is conserved across space and time. This niche conservatism hypothesis is of high practical relevance for conserving biodiversity. Here, we synthesized empirical evidence on this hypothesis for invasive species to investigate how their climatic niche changes between their native and introduced ranges. Our results supported the hypothesis overall, but we also found important differences among taxa with different characteristics and for different types of data. Our findings are not only relevant for predicting spatial distributions of invasive species in their exotic ranges but also for forecasting species responses to changing environments in the Anthropocene.
Reduced development of COVID-19 in children reveals molecular checkpoints gating pathogenesis illuminating potential therapeutics
Authors: Steinman Jonathan Baruch , Lum Fok Moon , Ho Peggy Pui-Kay , Kaminski Naftali , Steinman Lawrence
Published: September 2020

The reduced development of COVID-19 for children compared to adults provides some tantalizing clues on the pathogenesis and transmissibility of this pandemic virus. First, ACE2, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor, is reduced in the respiratory tract in children. Second, coronavirus associated with common colds in children may offer some protection, due to cross-reactive humoral immunity and T cell immunity between common coronaviruses and SARS-CoV-2. Third, T helper 2 immune responses are protective in children. Fourth, surprisingly, eosinophilia, associated with T helper 2, may be protective. Fifth, children generally produce lower levels of inflammatory cytokines. Finally, the influence of the downturn in the global economy, the impact of living in quarters among families who are the most at risk, and factors including the openings of some schools, are considered. Those most disadvantaged socioeconomically may suffer disproportionately with COVID-19.
Multi-domain functional metasurface with selectivity of polarization in operation frequency and time
Authors: Li Weihan , Qiu Tianshuo , Wang Jiafu , Yan Mingbao , Wang Xiaofeng , Wang Aiai , Jia Yuxiang , Han Yajuan , Qu Shaobo
Published: September 2020

In this paper, we propose the design of a multi-domain functional metasurface (MDFM) that can achieve selectivity of polarization in operation frequency and time. The MDFM consists of a wire grating as the front layer, a frequency selective surface as the middle layer and an active orthogonal wire grating loaded with positive-intrinsic-negative (PIN) diodes as the back layer. The front wire grating serves as a polarization selective surface that only passes electromagnetic (EM) waves polarized perpendicular to the wire, whereas the middle frequency selective surfaces exerts a pass-band in the frequency-domain. To further obtain selectivity in the time-domain, another orthogonal wire grating loaded with PIN diodes is adopted to switch on/off the pass-band. Three functional layers are combined to integrate the three selective functions. To verify this design idea, a MDFM operating at 3.19 GHz was designed, with a total thickness about λ/11. A prototype was fabricated and measured to validate the design. The experimental results are in satisfactory agreement with the simulated ones. Due to multi-fold selectivity, the MDFM can achieve high rejection for unwanted signals and may find wide applications in areas such as wireless communication, EM compatibility and stealthy radomes.
Impact of crystallization process in multilevel optical switching in Ge2Sb2Te5 and Ag5In5Sb60Te30 phase-change materials
Authors: Arjunan M S , Mondal Anirban , Durai Suresh , Adarsh K V , Manivannan Anbarasu
Published: September 2020

Phase change materials including GeSbTe and AgInSbTe have successfully demonstrated multilevel switching capabilities, yet achieving precise controllability and reproducibility are crucial towards technological applications. In this study, we demonstrate nine distinct optical levels in Ge2Sb2Te5 (GST225) and Ag5In5Sb60Te30 (AIST) phase-change materials using pump-probe experiments under identical device conditions and the role of the crystallization mechanism is examined for realization of reliable multi-level programming. Nucleation-dominated GST225 material corroborates improved performance characteristics of low threshold fluence (6 mJ cm−2), least optical variation (±0.25%), and high reflectivity contrast (∼2.5%) between any two consecutive levels as compared to growth-dominated AIST material. Furthermore, the opto-thermal simulations depict a gradual change in the crystalline fraction in GST225 and an abrupt change in AIST, which further confirms the improved controllability in nucleation-dominated crystallization. Hence, these identical measurements along with the opto-thermal simulations elucidate that the role and nature of crystallization play a critical role in precise control of variation of reflectivity in multi-level states of GST225 and AIST, respectively. These findings will be useful towards the development of reliable multi-bit phase-change photonic memory devices.
Time-varying fault feature extraction of rolling bearing via time–frequency sparsity
Authors: Yi Cancan , Qin Jiaqi , Huang Tao , Jin Zhangmin
Published: September 2020

The joint time–frequency (TF) distribution is a critical method of describing the instantaneous frequency that changes with time. To eliminate the errors caused by strong modulation and noise interference in the process of time-varying fault feature extraction, this paper proposes a novel approach called second-order time–frequency sparse representation (SOTFSR), which is based on convex optimization in the domain of second-order short-time Fourier transform (SOSTFT) where the TF feature manifests itself as a relative sparsity. According to the second-order local estimation of the phase function, SOSTFT can provide a sparse TF coefficient in the short-time Fourier transform (STFT) domain. To obtain the optimal TF coefficient matrix from noisy observations, it is innovatively formulated as a typical convex optimization problem. Subsequently, a multivariate generalized minimax concave penalty is employed to maintain the convexity of the least-squares cost function to be minimized. The aim of the proposed SOTFSR is to obtain the optimal STFT coefficient in the TF domain for extraction of time-varying features and for perfect signal reconstruction. To verify the superiority of the proposed method, we collect the multi-component simulation signals and the signals under variable speed from a rolling bearing with an inner ring fault. The experimental results show that the proposed method can effectively extract the time-varying fault characteristics.
The vortex state in FeSe superconducting thin film
Authors: Zhao Wan-Li , Zhu Xin , He Zhi-Hao , Gao Kuang-Hong , Li Zhi-Qing
Published: September 2020

We have investigated the low temperature isothermal current-voltage characteristics of FeSe epitaxial films with thickness of ∼ 360 nm at different magnetic fields parallel to the c axis. At zero magnetic field, with decreasing temperature a Berezinskii–Kosterlitz–Thouless transition, which often appears in two-dimensional (2D) superconductors, is observed. The current dependence of the voltage obeys the scaling relation V ∼ I
3 at the transition temperature

T

B
K
T

≈
4.7

 K, and the temperature dependence of sheet resistance follows the prediction of the Halperin-Nelson formula in the vicinity of

T

B
K
T

. When a magnetic field with magnitude 0.1 T

≲

μ
0

H
≲
6

 T is applied, the low temperature isothermal current-voltage data in each field can be scaled onto two different branches by using the scaling relation predicted by the vortex-glass theory. When comparing with the scaling relation, the dimensionality D can only be taken as 2, indicating a vortex-liquid phase to quasi-2D vortex-glass phase transition occurs in the FeSe film. The presence of Berezinskii–Kosterlitz–Thouless transition and the quasi-2D vortex-glass phase are related to the weak coupling between Fe-Se layers in the FeSe film.
SALT HRS Capabilities for Time Resolved Pulsation Analysis: A Test with the roAp Star α Circini*
Authors: Holdsworth D. L. , Brunsden E.
Published: September 2020

Spectroscopy is a powerful tool for detecting variability in the rapidly oscillating Ap (roAp) stars. The technique requires short integrations times and high resolution, and so is limited to only a few telescopes and instruments. To test the capabilities of the High Resolution Spectrograph (HRS) at the Southern African Large Telescope (SALT) for the study of pulsations in roAp stars, we collected 2.45 hr of high-resolution data of the well studied roAp star α Cir in a previously unused instrument configuration. We extracted radial velocity measurements using different rare earth elements, and the core of H
α
, via the cross correlation method. We performed the same analysis with a set of α Cir data collected with the High Accuracy Radial velocity Planet Searcher spectrograph to provide a benchmark for our SALT HRS test. We measured significant radial velocity variations in the HRS data and show that our results are in excellent agreement between the two data sets, with similar signal-to-noise ratio detections of the principal pulsation mode. With the HRS data, we report the detection of a second mode, showing the instrument is capable of detecting multiple and low-amplitude signals in a short observing window. We concluded that SALT HRS is well-suited for characterizing pulsations in Ap stars, opening a new science window for the telescope. Although our analysis focused on roAp stars, the fundamental results are applicable to other areas of astrophysics where high temporal and spectral resolution observations are required.
Anomalous

decay and its interference effects on gluon–gluon contribution at the LHC *
Authors: He Hua-Rong , Wan Xia , Wang You-Kai
Published: September 2020

We calculate the spinor helicity amplitudes of anomalous

decay. After embedding these analytic formulas into the MCFM package, we study the interference effects between the anomalous

process and the SM processes, which are indispensable in the Higgs off-shell region. Subsequently, the constraints on the anomalous couplings are estimated using LHC experimental data.
Two-neutron transfer reactions as a tool to study the interplay between shape coexistence and quantum phase transitions *
Authors: García-Ramos J.E. , Arias J.M. , Vitturi A.
Published: September 2020

The atomic mass table presents zones where the structure of the states changes rapidly as a function of the neutron or proton number. Among them, notable examples are the A ≈ 100 Zr region, the Pb region around the neutron midshell (N = 104), and the N ≈ 90 rare-earth region. The observed phenomena can be understood in terms of either shape coexistence or quantum phase transitions. The objective of this study is to find an observable that can distinguish between both shape coexistence and quantum phase transitions. As an observable to be analyzed, we selected the two-neutron transfer intensity between the 0+ states in the parent and daughter nuclei. The framework used for this study is the Interacting Boson Model (IBM), including its version with configuration mixing (IBM-CM). To generate wave functions of isotope chains of interest needed for calculating transfer intensities, previous systematic studies using IBM and IBM-CM were used without changing the parameters. The results of two-neutron transfer intensities are presented for Zr, Hg, and Pt isotopic chains using IBM-CM. Moreover, for Zr, Pt, and Sm isotopic chains, the results are presented using IBM with only a single configuration, i.e., without using configuration mixing. For Zr, the two-neutron transfer intensities between the ground states provide a clear observable, indicating that normal and intruder configurations coexist in the low-lying spectrum and cross at A = 98 → 100. This can help clarify whether shape coexistence induces a given quantum phase transition. For Pt, in which shape coexistence is present and the regular and intruder configurations cross for the ground state, there is almost no impact on the value of the two-neutron transfer intensity. Similar is the situation with Hg, where the ground state always has a regular nature. For the Sm isotope chain, which is one of the quantum phase transition paradigms, the value of the two-neutron transfer intensity is affected strongly.
Description of alpha-clustering of 8Be nucleus states in high-precision theoretical approach
Authors: Rodkin D. M. , Tchuvil’sky Yu. M.
Published: September 2020

Scrupulous theoretical study of 8Be nucleus states, both clustered and non-clustered, is performed over a wide range of excitation energies. The quantities that characterize the degree of the alpha-clustering of these states, i.e., spectroscopic factors, cluster form factors, and alpha-decay widths, are computed in the framework of the developed accurate ab initio approach. Other basic properties of the 8Be spectrum, including the binding and excitation energies and the mean values of the isospin, are calculated simultaneously. In the majority of instances, the results of the computation turn out to be in good agreement with the spectroscopic data. A number of predictions are made, and corresponding verification experiments are proposed. Prospects of the developed approach for nuclear spectroscopy are demonstrated.
Observational constraints on dark matter decaying via gravity portals *
Authors: Sun Xu-Dong , Dai Ben-Zhong
Published: September 2020

Global symmetry can guarantee the stability of dark matter particles (DMps). However, the nonminimal coupling between dark matter (DM) and gravity can break the global symmetry of DMps, which in turn leads to their decay. Under the framework of nonminimal coupling between scalar singlet dark matter (ssDM) and gravity, it is worth exploring the extent to which the symmetry of ssDM is broken. It is suggested that the total number of decay products of ssDM cannot exceed current observational constraints. Along these lines, the data obtained with satellites such as Fermi-LAT and AMS-02 suggest that the scale of ssDM global symmetry breaking can be limited. Because the mass of many promising DM candidates is likely to be in the GeV-TeV range, we determine reasonable parameters for the ssDM lifetime within this range. We find that when the mass of ssDM is around the electroweak scale (246 GeV), the corresponding 3σ lower limit of the lifetime of ssDM is

s. Our analysis of ssDM around the electroweak scale encompasses the most abundant decay channels of all mass ranges so that the analysis of the behavior of ssDM under the influence of gravity is more comprehensive.
Voronoi diagrams in quasi-2D hard sphere systems
Authors: Morley David Ormrod , Wilson Mark
Published: September 2020

Variants of the Voronoi construction, commonly applied to divide space, are analysed for quasi-two-dimensional hard sphere systems. Configurations are constructed from a polydisperse lognormal distribution of sphere radii, mimicking recent experimental investigations. In addition, experimental conditions are replicated where spheres lie on a surface such that their respective centres do not occupy a single plane. Significantly, we demonstrate that using an unweighted (no dependence on sphere size) two-dimensional Voronoi construction (in which the sphere centres are simply projected onto a single plane) is topologically equivalent to taking the lowest horizontal section through a three-dimensional construction in which the division of space is weighted in terms of sphere size. The problem is then generalised by considering the tessellations formed from horizontal sections through the three-dimensional construction at arbitrary cut height above the basal plane. This further suggests a definition of the commonly-applied packing fraction which avoids the counter-intuitive possibility of it becoming greater than unity. Key network and Voronoi cell properties (the fraction of six-membered rings, assortativity and cell height) and are analysed as a function of separation from the basal plane and the limits discussed. Finally, practical conclusions are drawn of direct relevance to on-going experimental investigations.
Results of ultra-high-energy cosmic rays from the Telescope Array
Authors: Sagawa H.
Published: September 2020

The Telescope Array (TA) is the largest ultra-high-energy cosmic ray (UHECR) observatory in the northern hemisphere. It consists of 507 surface scintillator detectors covering approximately 700 km2, and three fluorescence telescope sites overlooking the surface array. The aim of the TA is to explore the origin and nature of UHECR by measuring the energy spectrum and the distribution of arrival directions and mass composition of UHECR. Here, the recent results obtained by the TA are reported. Additionally, two extensions are presented: an extension of the observation area (TAx4) for detecting the highest-energy cosmic rays and the TA Low-Energy extension (TALE) exploring the transition from galactic to extragalactic cosmic rays.
Lower bound estimate for buckling in axially graded cantilever rods
Authors: Abdalla Hassan Mohamed Abdelalim , Novak Srnec Jelena , Casagrande Daniele
Published: September 2020

Functionally graded beams, bars and rods have been gaining a relevant consideration in engineering practice and research, taking into account variations of the material properties either in the transverse or in the longitudinal direction. Yet existing literature dealing with analytical study of structural instability for an arbitrary material longitudinal variation is still limited. In this paper, a variational approach to the buckling in axially graded cantilevers is developed within Euler-Bernoulli beam theory. Considering the large deflection static behavior and interpreting the first variation of the corresponding Action integral as a weak form of the associated Euler–Lagrange equation, the problem of analytically finding a lower bound estimate for the buckling load is investigated and solved for arbitrary variations of mechanical properties within an imposed condition on the maximal deflection of the free end. In particular, two examples of widely used material gradient forms have been considered and their lower bound buckling forces have been estimated in a closed form, compared with numerical results from literature developed within the linearized version of governing equations and validated using nonlinear finite element forecasts, showing promising results in terms of buckling prediction.
Romosozumab: A first-in-class sclerostin inhibitor for osteoporosis
Authors: Prather Caitlin , Adams Erin , Zentgraf Whitney
Published: September 2020

Purpose

The purpose of this article is to review the pharmacology, efficacy, and safety of the sclerostin inhibitor romosozumab for the treatment of osteoporosis, including data from clinical trials of the drug.

A review of the literature was performed by searching PubMed and MEDLINE for all relevant articles published between January 2014 and February 2020 using the keywords romosozumab, romosozumab-aqqg, osteoporosis, and fracture. All relevant English-language articles evaluating the pharmacology, efficacy, or safety of romosozumab for the treatment of osteoporosis in humans were included; poster presentations were excluded. Romosozumab has been approved by the Food and Drug Administration and is considered both safe and effective for the treatment of osteoporosis in high-risk postmenopausal females. Phase 2 and phase 3 clinical trials have shown a statistically significant decrease in new vertebral fractures and an increase in bone mineral density with romosozumab use, as compared with both placebo use and use of alternative osteoporosis therapies. The primary safety concern is a potential risk of cardiovascular events; additionally, hypocalcemia must be corrected prior to initiation. Romosozumab is the first anabolic medication that both increases bone formation and decreases bone resorption. Data suggest that romosozumab is more effective than oral bisphosphonates in preventing osteoporotic fractures, though cost and safety concerns must be considered.

Conclusion

Romosozumab is a novel, 12-month treatment option for postmenopausal women at high risk for osteoporotic fracture that both increases bone formation and decreases bone resorption.
GuidingNet: revealing transcriptional cofactor and predicting binding for DNA methyltransferase by network regularization
Authors: Ren Lixin , Gao Caixia , Duren Zhana , Wang Yong
Published: September 2020

The DNA methyltransferases (DNMTs) (DNMT3A, DNMT3B and DNMT3L) are primarily responsible for the establishment of genomic locus-specific DNA methylation patterns, which play an important role in gene regulation and animal development. However, this important protein family’s binding mechanism, i.e. how and where the DNMTs bind to genome, is still missing in most tissues and cell lines. This motivates us to explore DNMTs and TF’s cooperation and develop a network regularized logistic regression model, GuidingNet, to predict DNMTs’ genome-wide binding by integrating gene expression, chromatin accessibility, sequence and protein–protein interaction data. GuidingNet accurately predicted methylation experimental data validated DNMTs’ binding, outperformed single data source based and sparsity regularized methods and performed well in within and across tissue prediction for several DNMTs in human and mouse. Importantly, GuidingNet can reveal transcription cofactors assisting DNMTs for methylation establishment. This provides biological understanding in the DNMTs’ binding specificity in different tissues and demonstrate the advantage of network regularization. In addition to DNMTs, GuidingNet achieves good performance for other chromatin regulators’ binding. GuidingNet is freely available at https://github.com/AMSSwanglab/GuidingNet.