bluuebunny/crossref_metadata_2025 huggingface dataset:
Switchable quantum anomalous Hall effect in a ferromagnetic topological crystalline insulating NpSb monolayer
Authors: Sun Wenli , Li Xinying , Li Bingyang , Zou Xiaorong , Huang Baibiao , Dai Ying , Niu Chengwang
Published: April 2022

The combination of band topology and magnetic order provides an exciting platform for exploring prominent topological quantum effects, such as the quantum anomalous Hall (QAH) effect, which is well known to emerge when the ferromagnetic (FM) order is introduced in two-dimensional (2D) topological (crystalline) insulators. However, a topological phase transition between QAH insulators and magnetic topological (crystalline) insulators in 2D intrinsic magnets is seldom reported. Here, in contrast to previous magnetic doping, we predict that a switchable topological phase transition between a QAH insulator and a 2D topological crystalline insulator can emerge in an intrinsic FM NpSb monolayer via strain engineering. With the spin-up and spin-down manifolds being oppositely tunable, the calculated mirror Chern number, Chern number, and nontrivial edge states clearly confirm the topological phase transition as well as the QAH effect. Moreover, we reveal the feasibility of attaining the QAH effect while strain is introduced by an appropriate substrate. These results are of great scientific interest for exploring and understanding nontrivial topology in 2D magnets.
Independently controllable dual band filtering characteristics of a spoof surface plasmonic waveguide employing compound slot structure
Authors: Su Rong , Hu MingZhe , Zhang LePeng , Ren Yi , Yao Dayue , Xu Yanli , Zhang HaoChi
Published: April 2022

The dual band filtering characteristics of a spoof surface plasmonic waveguide (WG) loaded with a composite slot structure are studied in the present paper. The proposed composite slot structure enables the plasmonic WG to work at dual bands in the microwave region, where the working bandwidth can be flexibly adjusted with a broad isolation band between them. In particular, the second bandwidth can be adjusted independently without affecting the first passband by controlling the special parameter of the composite slot. As a demonstration, the measurement results of the proposed prototype filter illustrate that the plasmonic filtering WG has a dual bandpass performance with excellent frequency selectivity, where the insertion loss of the dual-band filter is less than −3 dB in the frequency from 2.7 GHz to 6.7 GHz and 7.7 GHz to 9.1 GHz, and the stopband rejection level is lower than −10 dB from 6.9 GHz to 7.5 GHz. Compared with the traditional dual band plasmonic filtering WG, the proposed filter has compact physical size, lower insertion loss in the passband and stronger isolation ability between the two passbands.
Two-parameter landscape of transport efficiency in mesoscopic networks: transitions from the Braess to normal regimes without a congestion relaxation
Authors: Lobanov A D , Lobanova A D , Pupasov-Maksimov A M
Published: April 2022

This paper deals with the Braess paradox in quantum transport. The scattering matrix formalism is used to consider a two-parameter family of mesoscopic conductors with the topology of the classical Braess transport network. The study investigates the mutual influence of the congestion and smoothness of the system on the Braess behavior. Both the Braess paradox and normal transport regimes coexist within the two-parametric landscape under the same congestion.
Ab initio screening of two-dimensional CuQ

x
and AgQ

x
chalcogenides
Authors: Inui Guilherme K , Silveira Julian F R V , Dias A C , Besse Rafael , Da Silva Juarez L F
Published: April 2022

Two-dimensional (2D) chalcogenides have attracted great interest from the scientific community due to their intrinsic physical–chemical properties, which are suitable for several technological applications. However, most of the reported studies focused on particular compounds and composition, e.g., MoS2, MoSe2, WS2, and WSe2. Thus, there is an increased interest to extend our knowledge on 2D chalcogenides. Here, we report a density functional theory (DFT) screening of 2D coinage-metal chalcogenides (MQ

x
), where M = Cu, Ag, Q = S, Se, Te, x = 0.5, 1.0, 1.5, 2.0, with the aim to improve our atomistic understanding of the physical–chemical properties as a function of cation (M), anion (Q), and composition (x). Based on 258 DFT calculations, we selected a set of 22 stable MQ

x
monolayers based on phonons analyses, where we identified 9 semiconductors (7 AgQ
x
and 2 CuQ
x
), with band gaps from 0.07 eV up to 1.67 eV, while the remaining systems have a metallic character. Using all 258 systems, we found a logarithmic correlation between the average weighted bond lengths and effective coordination number of cations and anions. As expected, the monolayer cohesive energies increase with the radius of the Q species (i.e., from S to Te). Furthermore, an increase in the anion size diminishes the work function for nearly all MQ

x
monolayers, which can be explained by the nature of the electronic states at the valence band maximum.
Electrokinetic separation of cfDNA in insulator-based dielectrophoresis systems: a linear model of cfDNA and investigation of effective parameters
Authors: Abdollahi Azita , Shokouhmand Hossein
Published: April 2022

In this study, a comprehensive numerical simulation was done to investigate the electrokinetic translocation of cfDNA molecule as well as the possibility of its detection and separation in insulator based dielectrophoresis (iDEP) systems. Modeling was done for the first time by solving the Poisson equation for the electrical potential, Naiver–Stokes (NS) equation for the fluid flow and energy equation for the heat transfer in the system and considering a coarse-grained bead-spring model to describe the conformational and geometrical changes of cfDNA molecule. The effect of the geometrical parameters of the system, the initial orientation of the molecule, electrical conductivity of the solution and zeta potential of the wall was investigated on the translocation and the minimum voltage required for cfDNA trapping. When the ratio of the inlet height to the constriction zone height is large enough, cfDNA molecules cannot pass through the nanopore and trap in the constriction zone. Also, it was found that the electrical conductivity of the solution is a limiting parameter to directly isolate cfDNA from pure plasma without dilution due to significant increase in the temperature of the system. Our results demonstrate the enormous potential of iDEP systems for rapid detection of cfDNA from diluted plasma under special electrical potential and geometrical parameters of the iDEP systems.
Investigation and optimization of a novel precision measurement method based on template matching
Authors: Zhao Chenyang , Xi Yueping , Shao Yizhi , Xue Wen , Deng Daxiang , Wu Yang
Published: April 2022

The polar microstructure is a 10 μm aperiodic surface pattern, which is designed to achieve nanoscale resolution and applied in the precision measurement area. In this paper, an investigation of the major factors of a novel template-matching-based precision measurement method that integrates with the polar microstructure and computer vision (IPMCV) is proposed. In order to optimize the measurement performance of the IPMCV method, three crucial factors are determined according to the template-matching method: the size of the global image, the size of the template image and the number of interpolated sub-pixels. According to the measurement accuracy, the size of the global image has little influence on the position error, but significantly influences the standard deviation value of the error gradually. In addition, the size of the template image helps to significantly improve the measurement accuracy, and the increase in the number of interpolated sub-pixels increases the measurement accuracy within a certain range but has no effect afterward. The experimental results have great significance on the determination and optimization of parameters for the IPMCV method to achieve a better measurement performance.
Pulsed eddy current testing for gap measurement of metal casing
Authors: Chen Xingle , Niu Hang
Published: April 2022

A pulsed eddy current testing (PECT) method is proposed to measure the gap of non-ferromagnetic metal casing. Firstly, the detection sensitivity to the casing gap of the voltage signal induced respectively by time-harmonic excitation current and by pulsed excitation current are calculated theoretically and compared. Then the advantages of PECT method for gap measurement are discussed. Secondly, the difference curve of the time-domain induced voltage signal between two gaps near the nominal value is presented. And the value of the induced voltage signal corresponding to the peak time of the difference curve is extracted to serve as the signal characteristic. Furthermore, using a calibrated casing, the function relationship between the signal characteristic and the casing gap is derived by curve fitting. Finally, the casing gap can be determined rapidly through the induced voltage at the peak time. This paper provides a reliable non-destructive testing method for the casing gap measurement, and compared with the existing sinusoidal ECT method, the PECT method can significantly improve the signal-to-noise ratio and the detection sensitivity to the casing gap.
Constructing MXene-PANI@MWCNTs heterojunction with high specific capacitance towards flexible micro-supercapacitor
Authors: Wang Qiangqiang , Fang Yongsheng , Cao Maosheng
Published: April 2022

Micro-supercapacitors (MSCs) are considered as the promising energy supply of miniaturized electronic devices. The electrode material, as one integral part, play a crucial role on the energy storage performance of MSCs. In our work, we constructed a heterojunction in MXene-PANI@MWCNTs (MPM) ternary composite, benefitting for the synergistic enhancement effect among MXene, polyaniline (PANI) and multiwall carbon nanotubes, an outstanding specific capacitance of 414 F g−1 (at 1 A g−1) has been achieved. MPM shows high capacitance retention at large current density (86.7%, at 10 A g−1) and long-term cycling stability of 90.4% for 10 000 cycles. Furthermore, we obtained MPM self-standing films, and constructed a flexible all-solid-state MSC based on the film electrode. A competitive charge storage capability of 30.2 mF cm−2 and long-term stability of 70.2% retention for 10 000 cycles was obtained in the MSC. Meanwhile, the MSC shows excellent flexibility, maintaining most capacitance under bending conditions. Moreover, using an integrated strategy, MSCs can obtain tunable voltages and currents that meet various practical requirements. All these results indicate that the MPM is an excellent charge storage material and will become a potential candidate for flexible energy-storage devices.
Experimental investigation of the electron sheath resonance (ESR) effect in parallel plate radio-frequency capacitively coupled plasmas
Authors: Ding Ling-ling , Lu Wen-qi , Zhang Quan-zhi , Xu Jun , Ding Zhen-feng , Wang You-nian
Published: April 2022

We have conducted a systematic experimental investigation on the electron heating mechanism named as electron sheath resonance (ESR) effect, with a parallel plate discharge configuration under various experimental conditions. In all conditions, a clear plasma density peak was observed at the magnetic field for ESR, providing a direct evidence for the effect. Further analysis suggests that the more significant ESR effect should appear at higher frequency, lower pressure discharges with larger electrodes. The results form a basis for further studies of the ESR effect, which is also meaningful to practical applications such as etching and thin film deposition processes.
A comparison of Au/n-Si Schottky diodes (SDs) with/without a nanographite (NG) interfacial layer by considering interlayer, surface states (Nss) and series resistance (Rs) effects
Authors: Demirezen Selçuk , Altındal Şemsettin , Azizian-Kalandaragh Yashar , Akbaş Ahmet Muhammed
Published: April 2022

In this paper, an organic interlayer, Rs, and Nss on the transport- mechanisms (TMs), both the Au/n-Si (MS) and Au/(Nanographite-PVP/n-Si (MPS) (SDs) were performed onto the same Si-wafer in same-conditions. Some electrical parameters of them have been investigated. The interface-traps/states (D
it
/N
ss) were extracted from the I

F
–V

F
data as function of energy (Ec–Ess). These results show that the N
ss for MPS is much-lower than MS SD and increase from the midgap-energy towards the E
c like U-shape. Double-logarithmic I

F
–V

F
graphs of them show three linear-regimes for low, intermediate, and high-voltages and in these regimes, TM are governed by ohmic, trap/space charge limited currents (TCLCs/SCLCs), respectively. All these results show that (NG:PVP) interlayer leads to an increase in rectifier-ratio (RR = I

F

/I

R
), BH, R
sh, and decrease in N
ss, reverse saturation-current (I
o), and n. Thus, (NG:PVP) can be successfully utilized as interfacial layer with high performance characteristics.
Analysis of the gradual transition from the near to the far field in single-slit diffraction
Authors: García-Sánchez Almudena , Sanz Ángel S
Published: April 2022

In Optics it is common to split up the formal analysis of diffraction according to two convenient approximations, in the near and far fields (also known as the Fresnel and Fraunhofer regimes, respectively). Within this scenario, geometrical optics, the optics describing the light phenomena observable in our everyday life, is introduced as the short-wavelength limit of near-field phenomena, assuming that the typical size of the aperture (or obstacle) that light is incident on is much larger than the light wavelength. With the purpose to provide an alternative view on how geometrical optics fits within the context of the diffraction theory, particularly how it emerges, the transition from the near to the far field is revisited here both analytically and numerically. Accordingly, first this transition is investigated in the case of Gaussian beam diffraction, since its full analyticity paves the way for a better understanding of the paradigmatic (and typical) case of diffraction by sharp-edged single slits. This latter case is then tackled both analytically, by means of some insightful approximations and guesses, and numerically. As it is shown, this analysis makes explicit the influence of the various parameters involved in diffraction processes, such as the typical size of the input (diffracted) wave or its wavelength, or the distance between the input and output planes. Moreover, analytical expressions have been determined for the critical turnover value of the slit width that separates typical Fraunhofer diffraction regimes from the behaviors eventually leading to the geometrical optics limit, finding a good agreement with both numerically simulated results and experimental data extracted from the literature.
Binding and energetics of oxygen at the CuInSe2 chalcopyrite and the CuInSe2/CdS interface
Authors: Marinopoulos A G
Published: April 2022

The introduction of oxygen in thin-film solar cells based on the CuInSe2 compound and related CuInSe2/CdS devices has been known to affect their electrical properties, with a tendency of neutralizing part of the donor density and favoring a p-type behavior for the CuInSe2 (CIS) absorber material. The present study employed calculations based on density-functional theory supplemented with a hybrid-functional approach to determine the energetics of oxygen incorporation in the bulk CIS compound and the CIS/CdS heterojunction interface. The latter was represented by two distinct faceted interface variants. Oxygen atoms were assumed to exist both as interstitial and substitutional impurities, in the latter case occupying vacant selenium sites. The calculations identified the structural relaxation patterns and examined the thermodynamic stability of the impurity as a function of the electron and the elemental chemical potentials. Oxygen was found to incorporate favourably at the core of the CIS/CdS interfaces, in most cases by taking up a bridging position within the nearest In–In pair. The sites of the lowest-energy oxygen configurations were found to be associated with a copper-poor local environment, owing to the presence of copper vacancies or the relaxation-induced breaking of a copper-oxygen bond. The electronic structures of the CIS/CdS interfaces were also studied by analyzing the site-projected and layer-resolved densities of states for several layers within the interfacial cores. Oxygen introduced deep-lying nonbonding levels and impurity-host bonding states in the valence-energy region.
Enhanced mechanical properties and corrosion resistance of nickel and nickel-phosphorous coatings fabricated by electrodeposition embedding with TiB2 ceramic particles
Authors: Zhong Ning , Ma Rong , Li Wei , Hu Yihuai , Li Wenge , Zhao Yuantao
Published: April 2022

Pure nickel (Ni), TiB2 reinforced nickel (Ni-TiB2), nickel-phosphorus (Ni-P), and TiB2 reinforced nickel-phosphorus (Ni-P-TiB2) composite coatings were deposited on AISI-1045 steel substrates from Watts bath and phosphorous-containing solution, respectively. The composition and microstructure of these coatings were analyzed by energy dispersive x-ray spectroscopy (EDS), scanning electron microscope (SEM) and x-ray diffraction (XRD) analysis. The properties of these coatings, including hardness, were assessed and compared. The electrochemical performance of these coatings was investigated in a 3.5 wt% sodium chloride solution using electrochemical spectroscopy (EIS) and the potentiodynamic polarization technique at room temperature. The effect of TiB2 on the microstructure, phase, and properties of the coatings was investigated. The results indicate that the incorporation of TiB2 particles in the nickel matrix greatly increased the hardness and anti-corrosion properties of the nickel coatings by refining of the microstructure and reducing the defects. The enhancement effect of TiB2 on Ni-P coating is not as significant as that of TiB2 on nickel coating. However, with the incorporation of TiB2 ceramic particles, the corrosion resistance and hardness of the Ni-P-TiB2 coating increased by about 50% and 10%, respectively, compared with the original Ni-P coating. The present study provides insight into the potential applications of novel TiB2 ceramic particle-reinforced nickel composite coatings in the areas of wear and corrosion resistance.
3D printed hydroxyapatite promotes congruent bone ingrowth in rat load bearing defects
Authors: Chakraborty Juhi , Roy Subhadeep , Ghosh Sourabh
Published: April 2022

3D porous hydroxyapatite (HAP) scaffolds produced by conventional foaming processes have limited control over the scaffold’s pore size, geometry, and pore interconnectivity. In addition, random internal pore architecture often results in limited clinical success. Imitating the intricate 3D architecture and the functional dynamics of skeletal deformations is a difficult task, highlighting the necessity for a custom-made, on-demand tissue replacement, for which 3D printing is a potential solution. To combat these problems, here we report the ability of 3D printed HAP scaffolds for in vivo bone regeneration in a rat tibial defect model. Rapid prototyping using the direct-write technique to fabricate 25 mm2 HAP scaffolds were employed for precise control over geometry (both external and internal) and scaffold chemistry. Bone ingrowth was determined using histomorphometry and a novel micro-computed tomography (micro-CT) image analysis. Substantial bone ingrowth was observed in implants that filled the defect site. Further validating this quantitatively by micro-CT, the Bone mineral density (BMD) of the implant at the defect site was 1024 mgHA ccm−1, which was approximately 61.5% more than the BMD found with the sham control at the defect site. In addition, no evident immunoinflammatory response was observed in the hematoxylin and eosin micrographs. Interestingly, the present study showed a positive correlation with the outcomes obtained in our previous in vitro study. Overall, the results suggest that 3D printed HAP scaffolds developed in this study offer a suitable matrix for rendering patient-specific and defect-specific bone formation and warrant further testing for clinical application.
Traditional town houses in Kyoto, Japan: present and future
Authors: Hokoi S , Iba C
Published: April 2022

Climate change is a hot topic that requires urgent countermeasures; heat islands in urban areas significantly influence our daily lives such as health problems represented by heat stroke and insomnia. The health problems caused by abnormally hot weather cannot be solved only through the passive design of buildings but require artificial measures for cooling by air conditioners. The electricity consumed by air conditioners in Japan has consistently increased annually, resulting in an increase in the consumption of fossil fuels. The heat discharged due to the cooling worsens the environmental conditions around us. From these viewpoints, energy-saving standards have been implemented as one countermeasure. In this paper, these issues and the countermeasures to be taken are investigated regarding “Kyo-machiya,” a traditional townhouse in Kyoto, Japan. Field survey on indoor environment was carried out both in summer and winter. As an example, indoor air flow is explained in detail. It is important from both thermal comfort (cooling in summer) and thermal discomfort (cold draft in winter) points of view. It is highly related to the building design such as atrium and fittings such as sliding doors used for partitioning off a house. It is also important for infection by virus. Finally, eco-friendly residences and life are discussed in connection with the Sustainable Development Goals (SDGs) through a new form of “Kyo-machiya,” the “Heisei-no-Kyo-machiya.”
Discovering pattern of space layouts from low-income housing: A discussion of the New Normal preparedness after the Covid-19 pandemic
Authors: Yahya A S , Ahmad M H , Hassan A A G
Published: April 2022

By the end of 2021, it is expected that the coronavirus (COVID-19) will shift from pandemic to endemic phase as the number of vaccinated people is increasing over time. It gives us hope as the endemic phase will allow us to live together with the virus. During the Covid-19 situation, people have become more creative and innovative for familiarising themselves with the New Normal. The next question is how is the existing housing for the low-income group ready to be suited with this situation? Therefore, this study will examine the concept of space design in housing units for the lower income group. The study adopted a case study approach based on housing layout from Kuala Lumpur, Bandung and Buckinghamshire. These housing layouts were analysed using the Space Syntax method for describing the meaning of space layout from a low-income perspective. This study found two consideration points, (1) the willingness of space to accommodate small business activities and to avoid the spread of epidemics in the domestic space, and (2) the willingness of the government to educate the public to cultivate small home entrepreneurship with the existing low-income routine and limited domestic spaces.
Onset of nonlinearity in a two-dimensional thin shear layer
Authors: Izawa Seiichiro , Oku Tatsuya , Nishio Yu , Fukunishi Yu
Published: April 2022

This study numerically investigates an early stage of nonlinear interaction for the better understanding of the onset of nonlinear behaviors. Two-dimensional shear flow is chosen as a canonical flow. When two disturbances of different wavenumbers satisfying no resonance condition are initially given, new components appear one after another while the original disturbances grow. The vorticity budget analysis shows that the beat of the two exciting modes plays an essential role in forming the sum and difference nonlinear components, namely the secondary modes. For the nonlinear interaction mechanism, the high vorticity around the center of the shear layer is locally transported in the transverse direction at specific streamwise sections where the amplitude of the vertical velocity fluctuation becomes relatively larger compared to other sections. The distance between these specific sections corresponds to the wavelength of the beat. The vertically dispersed vorticity will then be convected in the horizontal directions by the mean flow. As a result, several regions of concentrated vorticity appear which eventually develop into vortices. The amplification mechanism is found to be the same for both the primary and secondary modes, though the secondary modes arise from the additional perturbation deriving from the initial perturbation.
Thermal stress analysis and structural optimization of ladle nozzle based on finite element simulation
Authors: Rong Zichao , Yi Jianhong , Li Fengxian , Liu Yichun , Eckert Jürgen
Published: April 2022

The ladle nozzle is one of the most important components in metal smelting. The cracking phenomenon occurs due to excessive thermal stress, which seriously affects the performance and life of the ladle nozzle. In this paper, a new composite structure of ladle nozzle is proposed, which consists of two materials with different properties and costs. The thermal physical parameters of the material are measured by high temperature dynamic Young’s modulus test method, thermal expansion test and flashing method. Based on the new structural model of the composite ladle nozzle, finite element simulation is used to combine the material ontology model, contact mechanics model and heat transfer model to study the temperature and thermal stress distribution inside the composite structure of the ladle nozzle during the casting process by taking representative key points inside the ladle nozzle. There is a large temperature gradient in the area near the casting hole, and the farther away from the casting hole, the smaller the temperature change. The ladle nozzle structure was optimized and compared with the existing ladle nozzle structure. The results show that the optimized composite structure of the ladle nozzle has significantly lowered thermal stress extremes under thermal shock, while the thermal stress distribution tends to be more uniform, which can largely reduce the chance of crack generation. This study is of great significance for improving the reliability and service life of the ladle nozzle and reducing its production cost.
Hybrid short-term runoff prediction model based on optimal variational mode decomposition, improved Harris hawks algorithm and long short-term memory network
Authors: Sun Wei , Peng Tian , Luo Yuanlin , Zhang Chu , Hua Lei , Ji Chunlei , Ma Huixin
Published: April 2022

Runoff prediction is an important basis for rational allocation of basin water resources and plays a very important role in regional water resources management. In this study, a hybrid short-term runoff prediction model based on long short-term memory network (LSTM), improved Harris hawks optimization algorithm (IHHO) and optimal variational mode decomposition (OVMD) are proposed. Firstly, the original runoff data is decomposed into several sub-modes by OVMD, and then the sub-modes are reconstructed by phase space reconstruction (PSR). Secondly, the Harris hawks optimization algorithm is improved by the chaos map and the hill climbing algorithm. Then, the LSTM model is established for each sub-mode, and the improved Harris hawks optimization algorithm (IHHO) is used to optimize the number of hidden layer neurons and learning rate of the LSTM network. Finally, the results of all sub-modes are combined to obtain the finally runoff prediction result. In this study, seven control models are constructed and compared with the proposed model to verify the effectiveness of the proposed model in runoff prediction.
Where Is Air Quality Improving, and Who Benefits? A Study of PM2.5 and Ozone Over 15 Years
Authors: Bravo Mercedes A , Warren Joshua L , Leong Man Chong , Deziel Nicole C , Kimbro Rachel T , Bell Michelle L , Miranda Marie Lynn
Published: April 2022

In the United States, concentrations of criteria air pollutants have declined in recent decades. Questions remain regarding whether improvements in air quality are equitably distributed across subpopulations. We assessed spatial variability and temporal trends in concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) and ozone (O3) across North Carolina from 2002–2016, and associations with community characteristics. Estimated daily PM2.5 and O3 concentrations at 2010 Census tracts were obtained from the Fused Air Quality Surface Using Downscaling archive and averaged to create tract-level annual PM2.5 and O3 estimates. We calculated tract-level measures of: racial isolation of non-Hispanic Black individuals, educational isolation of non–college educated individuals, the neighborhood deprivation index (NDI), and percentage of the population in urban areas. We fitted hierarchical Bayesian space-time models to estimate baseline concentrations of and time trends in PM2.5 and O3 for each tract, accounting for spatial between-tract correlation. Concentrations of PM2.5 and O3 declined by 6.4 μg/m3 and 13.5 ppb, respectively. Tracts with lower educational isolation and higher urbanicity had higher PM2.5 and more pronounced declines in PM2.5. Racial isolation was associated with higher PM2.5 but not with the rate of decline in PM2.5. Despite declines in pollutant concentrations, over time, disparities in exposure increased for racially and educationally isolated communities.
Racial and Ethnic Inequities in Health: Examining the Contributions of the American Journal of Epidemiology to Advancing the Science
Authors: Borrell Luisa N , Crawford Natalie D
Published: April 2022

The perverseness of racial and ethnic inequities in the United States continues to implore the investigation of their causes. While there have been improvements in the health of the US population, these improvements have not been equally distributed. To commemorate the 100th anniversary of the American Journal of Epidemiology, in this commentary, we aim to highlight the Journal’s contributions to: 1) the definition and use of race and ethnicity in research, and 2) understanding racial and ethnic inequities, both empirically and methodologically, over the past decade. We commend the Journal for its contributions and for spearheading many of the challenges related to measuring and interpreting racial and ethnic data for the past 20 years. We identify 3 additional areas in which the Journal could make further impact to address racial and ethnic inequities: 1) devote a section in every issue of the Journal to scientific papers that make substantive epidemiologic or methodological contributions to racial and ethnic inequities in health; 2) update the Journal’s guidelines for authors to include justifying the use of race and ethnicity; and 3) diversify the field of epidemiology by bringing a new cadre of scholars from minoritized racial and ethnic groups who represent the most affected communities into the research process.
Testing generalized linear models with high-dimensional nuisance parameters
Authors: Chen Jinsong , Li Quefeng , Chen Hua Yun
Published: April 2022

Generalized linear models often have high-dimensional nuisance parameters, as seen in applications such as testing gene-environment interactions or gene-gene interactions. In these scenarios, it is essential to test the significance of a high-dimensional subvector of the model’s coefficients. Although some existing methods can tackle this problem, they often rely on the bootstrap to approximate the asymptotic distribution of the test statistic, and are thus computationally expensive. Here, we propose a computationally efficient test with a closed-form limiting distribution, which allows the parameter being tested to be either sparse or dense. We show that, under certain regularity conditions, the Type-I error of the proposed method is asymptotically correct, and we establish its power under high-dimensional alternatives. Extensive simulations demonstrate the good performance of the proposed test and its robustness when certain sparsity assumptions are violated. We also apply the proposed method to Chinese famine sample data in order to show its performance when testing the significance of gene-environment interactions.
Microbial community response to simulated diluted bitumen spills in coastal seawater and implications for oil spill response
Authors: Cobanli Susan E , Wohlgeschaffen Gary , Ryther Camilla , MacDonald Jessica , Gladwell Alison , Watts Taylor , Greer Charles W , Elias Miria , Wasserscheid Jessica , Robinson Brian , King Thomas L , Ortmann Alice C
Published: April 2022

Oil spills in coastal waters can have devastating impacts on local ecosystems, from the microscopic base through to mammals and seabirds. Increasing transport of diluted bitumen has led to concerns about how this novel product might impact coastal ecosystems. A mesocosm study determined that the type of diluent and the season can affect the concentrations of hydrocarbons entering the water column from a surface spill. Those same mesocosms were sampled to determine whether diluent type and season also affected the microbial response to a surface spill. Overall, there were no differences in impacts among the three types of diluted bitumen, but there were consistent responses to all products within each season. Although microbial abundances with diluted bitumen rarely differed from unoiled controls, community structure in these organisms shifted in response to hydrocarbons, with hydrocarbon-degrading bacteria becoming more abundant. The relative abundance of heterotrophic eukaryotes also increased with diluted bitumen, with few photosynthetic organisms responding positively to oil. Overall shifts in the microbial communities were minimal relative to spills of conventional oil products, with low concentrations of hydrocarbons in the water column. Oil spill response should focus on addressing the surface slick to prevent sinking or stranding to minimize ecosystem impacts.
Effects of Transcranial Direct Current Stimulation on Attentional Bias to Methamphetamine Cues and Its Association With EEG-Derived Functional Brain Network Topology
Authors: Khajehpour Hassan , Parvaz Muhammad A , Kouti Mayadeh , Hosseini Rafsanjani Taherehalsadat , Ekhtiari Hamed , Bakht Sepideh , Noroozi Alireza , Makkiabadi Bahador , Mahmoodi Maryam
Published: April 2022

Background

Although transcranial direct current stimulation (tDCS) has shown to potentially mitigate drug craving and attentional bias to drug-related stimuli, individual differences in such modulatory effects of tDCS are less understood. In this study, we aimed to investigate a source of the inter-subject variability in the tDCS effects that can be useful for tDCS-based treatments of individuals with methamphetamine (MA) use disorder (IMUD).

Methods

Forty-two IMUD (all male) were randomly assigned to receive a single-session of either sham or real bilateral tDCS (anodal right/cathodal left) over the dorsolateral prefrontal cortex. The tDCS effect on MA craving and biased attention to drug stimuli were investigated by quantifying EEG-derived P3 (a measure of initial attentional bias) and late positive potential (LPP; a measure of sustained motivated attention) elicited by these stimuli. To assess the association of changes in P3 and LPP with brain connectivity network (BCN) topology, the correlation between topology metrics, specifically those related to the efficiency of information processing, and the tDCS effect was investigated.

Results

The P3 amplitude significantly decreased following the tDCS session, whereas the amplitudes increased in the sham group. The changes in P3 amplitudes were significantly correlated with communication efficiency measured by BCN topology metrics (r = −0.47, P = .03; r = −0.49, P = .02). There was no significant change in LPP amplitude due to the tDCS application.

Conclusions

These findings validate that tDCS mitigates initial attentional bias, but not the sustained motivated attention, to MA stimuli. Importantly, however, results also show that the individual differences in the effects of tDCS may be underpinned by communication efficiency of the BCN topology, and therefore, these BCN topology metrics may have the potential to robustly predict the effectiveness of tDCS-based interventions on MA craving and attentional bias to MA stimuli among IMUD.
A Cohort Study on the Duration of Plasmodium falciparum Infections During the Dry Season in The Gambia
Authors: Collins Katharine A , Ceesay Sukai , Drammeh Sainabou , Jaiteh Fatou K , Guery Marc Antoine , Lanke Kjerstin , Grignard Lynn , Stone Will , Conway David J , D’Alessandro Umberto , Bousema Teun , Claessens Antoine
Published: April 2022

Background

In areas where Plasmodium falciparum malaria is seasonal, a dry season reservoir of blood-stage infection is essential for initiating transmission during the following wet season.

Methods

In The Gambia, a cohort of 42 individuals with quantitative polymerase chain reaction-positive P falciparum infections at the end of the transmission season (December) were followed monthly until the end of the dry season (May) to evaluate infection persistence. The influence of human host and parasitological factors was investigated.

Results

A large proportion of individuals infected at the end of the wet season had detectable infections until the end of the dry season (40.0%; 16 of 40). At the start of the dry season, the majority of these persistent infections (82%) had parasite densities >10 p/µL compared to only 5.9% of short-lived infections. Persistent infections (59%) were also more likely to be multiclonal than short-lived infections (5.9%) and were associated with individuals having higher levels of P falciparum-specific antibodies (P = .02).

Conclusions

Asymptomatic persistent infections were multiclonal with higher parasite densities at the beginning of the dry season. Screening and treating asymptomatic infections during the dry season may reduce the human reservoir of malaria responsible for initiating transmission in the wet season.
Modelling the ionization state of Type Ia supernovae in the nebular phase
Authors: Shingles Luke J , Flörs Andreas , Sim Stuart A , Collins Christine E , Röpke Friedrich K , Seitenzahl Ivo R , Shen Ken J
Published: April 2022

The nebular spectra of Type Ia supernovae (⪆100 d after explosion) consist mainly of emission lines from singly and doubly ionized Fe-group nuclei. However, theoretical models for many scenarios predict that non-thermal ionization leads to multiply ionized species whose recombination photons ionize and deplete Fe+, resulting in negligible [Fe ii] emission. We investigate a method to determine the collisional excitation conditions from [Fe ii] line ratios independently from the ionization state and find that it cannot be applied to highly ionized models due to the influence of recombination cascades on Fe+ level populations. When the ionization state is artificially lowered, the line ratios (and excitation conditions) are too similar to distinguish between explosion scenarios. We investigate changes to the treatment of non-thermal energy deposition as a way to reconcile overionized theoretical models with observations and find that a simple work function approximation provides closer agreement with the data for sub-Mch models than a detailed Spencer–Fano treatment with widely used cross-section data. To quantify the magnitude of additional heating processes that would be required to sufficiently reduce ionization from fast leptons, we artificially boost the rate of energy loss to free electrons. We find that the equivalent of as much as an eight times increase to the plasma loss rate would be needed to reconcile the sub-Mch model with observed spectra. Future studies could distinguish between reductions in the non-thermal ionization rates and increased recombination rates, such as by clumping.
The origin of correlations between mass, metallicity, and morphology in galaxies from the eagle simulation
Authors: Zenocratti L J , De Rossi M E , Theuns T , Lara-López M A
Published: April 2022

Observed and simulated galaxies exhibit correlations between stellar mass, metallicity, and morphology. We use the eagle cosmological simulation to examine the origin of these correlations for galaxies in the stellar mass range $10^9~\rm {M_\odot } \leqslant \ {\it M}_\star \leqslant 10^{10}~\rm {M_\odot }$, and the extent to which they contribute to the scatter in the mass–metallicity relation. We find that rotationally supported disc galaxies have lower metallicity than dispersion supported spheroidal galaxies at a given mass, in agreement with previous findings. In eagle, this correlation arises because discs form stars at later times, redshift $z \leqslant 1$, from the accretion of low-metallicity gas, whereas spheroidal galaxies galaxies typically form stars earlier, mainly by consumption of their gas reservoir. The different behaviour reflects the growth of their host dark matter halo: at a given stellar mass, disc galaxies inhabit dark matter haloes with lower mass that formed later compared to the haloes of spheroidal galaxies. Halo concentration plays a secondary role.
Probing spectral and temporal evolution of the neutron star low-mass X-ray binary 4U 1724–30 with AstroSat
Authors: Kashyap Unnati , Chakraborty Manoneeta , Bhattacharyya Sudip
Published: April 2022

We report the broad-band spectro-temporal study of the poorly studied accreting neutron star (NS) low mass X-ray binary (LMXB) 4U 1724–30 using data from Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counters (LAXPC) instruments on board AstroSat. The dim persistent LMXB source was observed with AstroSat over 4 epochs in 2017, all of which corresponded to a low-luminosity non-thermal emission dominated (hard/island) emission state with modest spectral evolution. All the X-ray broad-band spectra can be modelled by a combination of thermal emission from the NS boundary layer (BL) or NS surface and a non-thermal emission component possibly originating from the inverse Comptonization of the disc seed photons. We investigate the presence of frequency and energy-dependent variabilities to probe the origin of the disc/coronal fluctuations. We also report the detection of a Type-I X-ray burst displaying a photospheric radius expansion (PRE). During the burst, a hard X-ray shortage in the 30–80 keV energy band and the enhancement of the persistent emission reveal the burst feedback on the overall accretion process. Using the touch-down burst flux ∼4.25 × 10−8 erg s−1 cm−2, the distance of the source is estimated as ∼8.4 kpc.
Confirming new changing-look AGNs discovered through optical variability using a random forest-based light-curve classifier
Authors: López-Navas E , Martínez-Aldama M L , Bernal S , Sánchez-Sáez P , Arévalo P , Graham Matthew J , Hernández-García L , Lira P , Rojas Lobos P A
Published: April 2022

Determining the frequency and duration of changing-look (CL) active galactic nuclei (AGNs) phenomena, where the optical broad emission lines appear or disappear, is crucial to understand the evolution of the accretion flow around supermassive black holes. We present a strategy to select new CL candidates starting from a spectroscopic type 2 AGN sample and searching for current type 1 photometric variability. We use the publicly available Zwicky Transient Facility alert stream and the Automatic Learning for the Rapid Classification of Events light-curve classifier to produce a list of CL candidates with a highly automated algorithm, resulting in 60 candidates. Visual inspection reduced the sample to 30. We performed new spectroscopic observations of six candidates of our clean sample, without further refinement, finding the appearance of clear broad Balmer lines in four of them and tentative evidence of type changes in the remaining two, which suggests a promising success rate of ≥66 per cent for this CL selection method.
High-throughput site-specific N-glycoproteomics reveals glyco-signatures for liver disease diagnosis
Authors: Sun Zhenyu , Fu Bin , Wang Guoli , Zhang Lei , Xu Ruofan , Zhang Ying , Lu Haojie
Published: April 2022

The glycoproteome has emerged as a prominent target for screening biomarkers, as altered glycosylation is a hallmark of cancer cells. In this work, we incorporated tandem mass tag labeling into quantitative glycoproteomics by developing a chemical labeling-assisted complementary dissociation method for the multiplexed analysis of intact N-glycopeptides. Benefiting from the complementary nature of two different mass spectrometry dissociation methods for identification and multiplex labeling for quantification of intact N-glycopeptides, we conducted the most comprehensive site-specific and subclass-specific N-glycosylation profiling of human serum immunoglobulin G (IgG) to date. By analysing the serum of 90 human patients with varying severities of liver diseases, as well as healthy controls, we identified that the combination of IgG1-H3N5F1 and IgG4-H4N3 can be used for distinguishing between different stages of liver diseases. Finally, we used targeted parallel reaction monitoring to successfully validate the expression changes of glycosylation in liver diseases in a different sample cohort that included 45 serum samples.
Reconciling Garnet Lu–Hf and Sm–Nd and Monazite U–Pb Ages for a Prolonged Metamorphic Event, Northern New Mexico
Authors: Bollen Elizabeth M , Stowell Harold H , Aronoff Ruth F , Stotter Sara V , Daniel Christopher G , McFarlane Christopher R M , Vervoort Jeffrey D
Published: April 2022

Garnet Sm–Nd and Lu–Hf isotopic data are increasingly used in tandem to characterize tectono-metamorphic events and their duration because the two chronometers may yield a progression from older Lu–Hf to younger Sm–Nd ages. In this contribution, we utilize garnet compositional zoning and monazite U–Pb ages to evaluate explanations for differences in garnet Sm–Nd and Lu–Hf ages for low- to mid-amphibolite facies rocks from the Picuris and Tusas Mountains, New Mexico. Ten Sm–Nd ages, eight Lu–Hf garnet ages (6 previously published), and four matrix monazite U–Pb dates span 1422–1370 Ma, 1456–1399 Ma, and 1377–1356 Ma, respectively. The weighted means of garnet ages are 1398 ± 11 Ma for Sm–Nd (N = 10/10) and 1402 ± 4 Ma for Lu–Hf (N = 6/8); however, Sm–Nd and Lu–Hf ages from three samples differ by 29, 34, and 55 my with differences between 2σ age envelopes of 12, 9, and 38 my., respectively. In these samples, primary Lu and Sm zoning in garnet, diffusion modification of zoning, or disequilibrium is sufficient to cause older Lu–Hf ages and younger Sm–Nd ages. Alternatively, two of the three Lu–Hf ages, c. 1450 Ma, may reflect the onset of a prolonged regional event or an earlier thermal event, and the three c. 1370 Ma garnet Sm–Nd ages may reflect diffusional re-equilibration. These three c. 1370 Ma ages are indistinguishable from the monazite ages, and garnet have trace element zoning consistent with diffusional alteration of growth zoning in Sm and Nd but not Lu and Hf. Garnet from the other seven samples have prograde zoning with little to no evidence for diffusional relaxation of zoning in these elements. We conclude that the majority of garnet preserve primary compositions and indistinguishable garnet ages of c. 1400 Ma, indicating a c. 22 my garnet growth history based on weighted mean. The two oldest c. 1450 Lu–Hf and three youngest c. 1370 Sm–Nd garnet ages require an earlier thermal history and modification of garnet composition, respectively. Results of this study redefine the youngest extent of amphibolite facies metamorphism during the Picuris orogeny to at least c. 1370 Ma.