bluuebunny/crossref_metadata_2025 huggingface dataset:
Defect-insensitive current–voltage characteristics of Schottky barrier diode formed on heteroepitaxial α-Ga2O3 grown by mist chemical vapor deposition
Authors: Maeda Takuya , Okigawa Mitsuru , Kato Yuji , Takahashi Isao , Shinohe Takashi
Published: December 2020

An n-type α-Ga2O3 layer was grown by mist chemical vapor deposition on a sapphire substrate, and a Ti/α-Ga2O3 Schottky barrier diode was fabricated. Although the α-Ga2O3 layer has a high threading dislocation density (larger than 109 cm−2), the ideality factor of 1.03 was obtained from the forward current–voltage characteristic in the range of 298 K–423 K, indicating the clear thermionic emission transport. The reverse current–voltage characteristic was also investigated, and the leakage current showed good agreement with the theoretical calculation based on the thermionic field emission model without any fitting parameter in the temperature range of 298 K–423 K.
The effect of sub-second intervals of ArF laser irradiation on the formation of periodic micro-swelling structures on silicone rubber surfaces
Authors: Yoshida Tsuyoshi , Okoshi Masayuki
Published: December 2020

Surface modification and microstructure formation of silicone rubber are gathering attention as popular methods of wettability control for microfluidic devices and biomedical applications. In this report, micro-swelling structures were fabricated on silicone rubber surfaces by ArF laser irradiation at various pulse repetition rates. The average height of the swelling structures shows a negative correlation with the pulse repetition rates of 2 Hz–20 Hz. The relationship between the microstructure height and the number of ArF laser shots was investigated at 2 Hz, 6 Hz, and 20 Hz pulse repetition rates, and it is presented that the growth of microstructures saturates with the smaller number of shots at the higher pulse repetition rate. These results imply the possibility of other competing mechanisms that disturb the swelling of silicone rubber by the ArF laser irradiation. The Attenuated Total reflection Fourier Transform Infrared spectroscopy measurement of the silicone rubber surface shows that the desorption of the –CH3 group proceeds more efficiently at the higher pulse repetition rate. It is concluded that the modification of silicone to the silica-like structure that increases in surface hardness disturbs the growth of the swelling structure, and the sub-second intervals of the ArF laser pulse suppress the modification of silicone to the silica-like structure. The understanding of the processes after photodissociation contributes not only to the effective formation of microstructures but also to the chemical modification of the silicone rubber surface.
Partial coalescence of a drop on a larger-viscosity pool
Authors: Alhareth Abdullah A. , Thoroddsen Sigurdur T.
Published: December 2020

When a low-viscosity drop coalesces with a pool surface of the same liquid, it often portrays partial coalescence, where it pinches off a daughter droplet from its top. Such partial coalescence can also occur for a drop spreading on a strongly hydrophilic solid surface. Herein, we investigate the partial coalescence of a low-viscosity drop with a pool surface, when the viscosity of the miscible pool is changed from low to very high, in other words, spanning the conditions from a pool to a solid surface. We find that above a certain pool viscosity, the partial coalescence transitions to second-stage coalescence with a much smaller satellite droplet. This occurs because higher pool viscosity prevents drainage from the drop into the pool, which, in turn, increases the axial curvature in the neck connecting the primary satellite to the drop, thereby preventing the first-stage pinch-off.
Australia and the International Astronomical Union: the 2003 Sydney General Assembly
Authors: Lomb Nick
Published: December 2020

Thirty years after the first International Astronomical Union general assembly in Australia, another was held, again in Sydney. Organisation of the 2003 general assembly was complex as the IAU and would-be participants had much greater expectations than at the previous event. Australia had been awarded the 2003 general assembly six years earlier during the assembly at Kyoto, Japan. Full advantage was taken of the intervening time with the setting up of a National Organising Committee that planned the conference together with a professional conference organiser. Formal responsibility for the conference was undertaken by the Astronomical Society of Australia since that role had to be undertaken by a legally constituted body. As the date of the general assembly approached there were fears of insufficient registered participants to cover expenses due to the discouragement of international travel by terrorist incidents, the Iraq war and, especially, the SARS epidemic. In the end, the conference had a good response so that it could go ahead with an opening at the Sydney Opera House and could offer a wide-ranging scientific program. There were numerous related meetings, such as those on women in astronomy, astronomical education and light pollution. As well, an extensive outreach program brought astronomy not only to people in Sydney, but to people around the country.
Stock structure of Pacific cod (Gadus macrocephalus) around the Korean Peninsula: an otolith microchemical perspective
Authors: Stone Kali R. , Kastelle Craig R. , Benson Irina M. , Helser Thomas E. , Short Jonathan A. , Kang Sukyung
Published: December 2020

Sustainable management of fishery resources is predicated on a foundational understanding of the biogeography of fish stocks and the delineation of stocks into appropriate management units. Despite notable fluctuations in the catch of commercially valuable Pacific cod (Gadus macrocephalus) in South Korea, relatively little is known regarding the stock structure and migratory trends of this species in the region. Here, otolith microchemistry was used to evaluate the stock structure and ontogenetic migratory trends of Pacific cod from five spawning grounds around the Korean Peninsula. Statistically significant between-region discrimination was evident and resolved Pacific cod around the Korean Peninsula into two distinct stocks. Specimens were classified to region of capture using quadratic discriminant analysis of age-0 and capture elemental signatures with overall accuracies of 71.12 and 79.1% respectively, lending support to the notion that Pacific cod demonstrate natal philopatry. Analysis of the elemental signatures over the first 2 years of life exhibited clear trends indicative of shifts in habitat use, suggesting that trace elements function well as indicators of ontogenetic migration. Our work provides information that is complementary to other direct and indirect methods of monitoring migratory trends and delineating stocks, which are integral components of effective species and ecosystem management plans.
Young Adult Perspectives on their Respiratory Health Symptoms Since Vaping
Authors: Kechter Afton , Schiff Sara J. , Simpson Kelsey A. , Ceasar Rachel C. , Braymiller Jessica L. , McConnell Rob , Leventhal Adam M. , Barrington-Trimis Jessica L.
Published: December 2020

Background

Vaping among young adults (YA) has been associated with adverse respiratory health outcomes. However, key gaps remain in the literature including perspectives from YA vapers on perceived respiratory health symptoms since vaping, how they describe those symptoms and related experiences, and factors to which they attribute their respiratory health symptoms.

Methods

Participants ( N = 35) were 18–25 years old and self-reported as currently vaping at least once per week. In-depth, semi-structured qualitative interviews were conducted using an open-ended interview guide designed to elicit respondents’ subjective vaping-related experiences. We used a thematic analysis to interpret the transcripts.

Results

Participants reported adverse respiratory health symptoms (e.g., phlegm, cough, pain in lungs) that some attributed to vaping. Participants compared what is known about vaping to what is known about combustible cigarettes and described continued use of vaping products despite perceived adverse respiratory health consequences. Some participants attributed their symptoms to preexisting medical conditions (e.g., asthma) and to heavy vaping. Some described a decline in exercise-related endurance since vaping. Some participants also reported that they experienced worse respiratory symptoms when using specific brands and products (e.g., JUUL and nicotine salt formulation).

Conclusions

This study provides powerful accounts from YA vapers about their experience of respiratory health symptoms that they ascribe to vaping. Future research is needed to evaluate the prevalence and severity, as well as the risk and protective factors, of adverse respiratory health symptoms associated with vaping. Addiction prevention and treatment efforts for YA vapers may help curtail adverse respiratory health impact from vaping.
How should we Define “Rural” when Investigating Rural Tobacco use in the United States?
Authors: Roberts Megan E. , Doogan Nathan J. , Tanenbaum Erin , Stillman Frances A. , Mumford Elizabeth A. , Chelluri Devi , Wewers Mary Ellen
Published: December 2020

Purpose

Investigations into rural tobacco-related disparities in the U.S. are hampered by the lack of a standardized approach for identifying the rurality—and, consequently, the urbanicity—of an area. Therefore, the purpose of this study was to compare the most common urban/rural definitions (Census Bureau, OMB, RUCA, and Isolation) and determine which is preferable for explaining the geographic distribution of several tobacco-related outcomes (behavior, receiving a doctor's advice to quit, and support for secondhand smoke policies).

Methods

Data came from The Current Population Survey Tobacco Use Supplement. For each tobacco-related outcome, one logistic regression was conducted for each urban/rural measure. Models were then ranked according to their ability to explain the data using Akaike information criterion (AIC).

Results

Each definition provided very different estimates for the prevalence of the U.S. population that is considered “rural” (e.g., 5.9% for the OMB, 17.0% for the Census Bureau). The OMB definition was most sensitive at detecting urban/rural differences, followed by the Isolation scale. Both these measures use strict, less-inclusive criteria for what constitutes “rural.”

Conclusions

Overall, results demonstrate the heterogeneity across urban/rural measures. Although findings do not provide a definitive answer for which urban/rural definition is the best for examining rural tobacco use, they do suggest that the OMB and Isolation measures may be most sensitive to detecting many types of urban/rural tobacco-related disparities. Caveats and implications of these findings for rural tobacco use disparities research are discussed. Efforts such as these to better understand which rural measure is appropriate for which situation can improve the precision of rural substance use research.
Null hypersurfaces in Kerr–Newman–AdS black hole and super-entropic black hole spacetimes
Authors: Imseis Michael T N , Al Balushi Abdulrahim , Mann Robert B
Published: December 2020

A three-dimensional light-like foliation of a spacetime geometry is one particular way of studying its light cone structure and has important applications in numerical relativity. In this paper, we execute such a foliation for the Kerr–Newman–AdS black hole geometry and compare it with the lightlike foliations of the Kerr–AdS and Kerr–Newman black holes. We derive the equations that govern this slicing and study their properties. In particular, we find that these null hypersurfaces develop caustics inside the inner horizon of the Kerr–Newman–AdS black hole, in strong contrast to the Kerr–AdS case. We then take the ultra-spinning limit of the Kerr–Newman–AdS spacetime, leading to what is known as a super-entropic black hole, and show that the null hypersurfaces develop caustics at a finite distance outside the event horizon of this black hole. As an application, we construct Kruskal coordinates for both the Kerr–Newman–AdS black hole and its ultra-spinning counterpart.
Kasner-like regions near crushing singularities
*
Authors: Lott John
Published: December 2020

We consider vacuum spacetimes with a crushing singularity. Under some scale-invariant curvature bounds, we relate the existence of Kasner-like regions to the asymptotics of spatial volume densities.
Lipschitz stability for an inverse source scattering problem at a fixed frequency
*
Authors: Li Peijun , Zhai Jian , Zhao Yue
Published: December 2020

This paper is concerned with an inverse source problem for the three-dimensional Helmholtz equation by a single boundary measurement at a fixed frequency. We show the uniqueness and a Lipschitz-type stability estimate under the assumption that the source function is piecewise constant on a domain which is made of a union of disjoint convex polyhedral subdomains.
A bimodal γ′ phase precipitation in Ni–Al alloys with preaging and continuous cooling: phase-field simulation
Authors: Chen Xi , Li Yongsheng , Yan Zhengwei , Shi Shujing , Wang Dong , Lai Kunwu , Chen Jing
Published: December 2020

A bimodal precipitation with primary and secondary γ′ phase in Ni-17 at.% Al alloys was produced via preaging and continuous cooling. The morphology and composition evolution of γ′ phase during cooling process were studied by using phase-field simulation, the bimodal precipitation mechanism was declared. The content of Al in secondary γ′ phase is lower than the equilibrium composition because of the slower atom diffusion during continuous cooling. With the increase of cooling rates, the volume fraction and average radius of primary and secondary γ′ phase are reduced, the number density of secondary γ′ phase increases; in addition, the inter-distance of particle size distribution of primary and secondary γ′ phase is widen. A long time of isothermal preaging reduces the precipitation and growth of secondary γ′ phase. The hybrider precipitates with bimodal size distribution of γ′ phase help optimizing the precipitates morphology of nickel based alloys.
Characterization of the inhomogeneity of Pt/CeO
x
/Pt resistive switching devices prepared by magnetron sputtering
Authors: Li Changfang , Zhang Baolin , Qu Zhaozhu , Zhao Hongbin , Li Qixin , Zeng Zhaohui , Yang Rusen
Published: December 2020

There are unrevealed factors that bring about the performance variations of resistive switching devices. In this work, Pt/CeO
x
/Pt devices prepared by magnetron sputtering showed rectification in their asymmetrical current–voltage (I–V) curves during voltage sweeps. X-ray photoelectron spectroscopy showed that the deposited CeO
x
film had an inhomogeneous composition, and more oxygen vacancies existed in CeO
x
near the top electrode. The asymmetrical resistance change of the Pt/CeO
x
/Pt devices can be explained by the presence of more charged oxygen vacancies in CeO
x
near the top electrode, along with the Schottky conduction mechanism. This work reveals that the compositional inhomogeneity is inevitable in the magnetron sputtering of oxide targets like CeO2 and can be an important source of device-to-device and cycle-to-cycle variations of memristors.
A tale of four quadrants: disambiguating inverse tangents
Authors: Cameron Reed B
Published: December 2020

A simple algorithm for resolving directional ambiguities in inverse tangent computations is developed.
Guidelines and procedure for tailoring high-performance, steady-state traveling waves for propulsion and solid-state motion
Authors: Musgrave Patrick F , Albakri Mohammad I , Phoenix Austin A
Published: December 2020

Structure-Borne Traveling Waves (SBTWs) have significant promise as a means of underwater propulsion, solid-state motion, and drag reduction. However, there is limited understanding over how to tailor SBTWs for these applications. This study establishes guidelines and a procedure for tailoring SBTWs on thin-walled two-dimensional (2D) surfaces. These guidelines were specifically crafted to yield SBTWs favorable for propulsion and solid-state motion: propagation along a uniform direction and with consistent amplitude. SBTWs are steady-state traveling waves generated by taking advantage of a surface’s modal properties (i.e. mode shapes). This novel mechanism provides significant benefits including a minimal actuation footprint, a wide frequency bandwidth, and active variability (propagation direction, wavelength, etc). However, this mechanism also introduces a dependence on the mode shapes and actuator location. Thus, to tailor SBTWs favorable for propulsion the relationship between SBTWs, the mode shapes, and actuator locations must be understood. Eight Guidelines governing this relationship are established. These Guidelines are demonstrated using SBTWs generated on a previously validated model of a 2D plate. Among others, it is shown that the frequency bandwidth can be broken into distinct frequency regions, and each region can be classified as yielding favorable or unfavorable SBTWs. A multi-step procedure is then introduced that enables SBTWs to be tailored on any thin-walled surface. Numerically or experimentally applicable, the actuator configuration can be defined to tailor SBTWs with a specific propagation direction; all that is required is knowledge of the mode shapes. Finally, a case study is presented in which the guidelines and procedure are implemented to tailor SBTWs on a trapezoidal surface. Two different sets of SBTWs are tailored, each propagating in different directions and with various wavelengths. Thus, the established guidelines and procedure enable SBTWs to be tailored for specific applications, such as propulsion and solid-state motion.
Antibacterial and anti-viral effects of silver nanoparticles in medicine against COVID-19—a review
Authors: Teirumnieks Edmunds , Balchev Ivaylo , Ghalot Risham Singh , Lazov Lyubomir
Published: December 2020

The article reviews the research on disinfecting the air through air filters and ventilation systems using silver nanoparticles (Ag NPs) (encouraged from the present situation of COVID-19) focusing on stopping the spreading of deadly viruses. The primary goal of the research is to demonstrate possible antiviral Ag NP formulations to be delivered by inhalation, to minimize the worsening of respiratory system infections. The basic design of the study includes a bibliometric analysis of the study of the effect of Ag NPs on the disinfection of viral infections. The research will discuss the idea of the use of laser ablation with Ag NPs for antiviral and antibacterial effects. The research article results in compelling evidence for the use of Ag NPs for medicinal purposes for infectious diseases/viruses and will contribute to the progress of medical science to protect healthcare workers from dangerous viruses at medical institutions. Practically, the research will generate a sterile system, which might be employed by every public or private institution economically with Ag NPs (because of their antimicrobial properties).
Cumulative loading of the ion trap by laser ablation of thorium target in buffer gas
Authors: Derevyashkin S P , Borisyuk P V , Khabarova K Yu , Kolachevsky N N , Strelkin S A , Tkalya E V , Tregubov D O , Tronin I V , Yakovlev V P
Published: December 2020

We describe a method that allows accumulation in a Paul trap of a large number of ions obtained from multiple laser ablation pulses, and therefore solving the problem of a single pulse that usualy gives rise to final trapping of too few ions. The proposed method of the cumulative trap loading was based on interaction with a buffer gas that provided a friction force. The method was applied to triply charged thorium ions and trapped a total of 106 ions. Numerical analysis of the ion motion allowed the experimental parameters to be optimized for the most effective implementation of the technique.
Generation of non-integer high-order harmonics and significant enhancement of harmonic intensity*
Authors: Xia Chang-Long , Lan Yue-Yue , Miao Xiang-Yang
Published: December 2020

High-order harmonics from helium atom in the orthogonally two-color (OTC) laser field are investigated by solving the two-dimensional time-dependent Schrödinger equation. Non-integer high-order harmonics are obtained in some ratio of frequencies of two components. Pure odd and even harmonics from atoms could be separated in two components by adjusting the ratio of frequencies in OTC scheme, and the resolution of harmonics is improved at the same time. The physical mechanism is explained by the periodicity of dipole. With the same intensity of the incident laser, the intensity of the high-order harmonics from the OTC field scheme is improved by three orders of magnitude compared to the monochromatic laser field scheme. A theoretical scheme is provided for experimentally achieving improving energy resolution and separation of pure odd and even harmonics in atoms. Also, we provide a means for improving harmonic intensity.
Numerical simulation of super-continuum laser propagation in turbulent atmosphere*
Authors: Li Ya-Qian , Zhu Wen-Yue , Qian Xian-Mei
Published: December 2020

Considering the atmospheric extinction and turbulence effects, we investigate the propagation performances of super-continuum laser sources in atmospheric turbulence statistically by using the numerical simulation method, and the differences in propagation properties between the super-continuum (SC) laser and its pump laser are also analyzed. It is found that the propagation characteristics of super-continuum laser are almost similar to those of the pump laser. The degradation of source coherence degree may cause the relative beam spreading and scintillation indexes to decrease at different propagation distances or different turbulence strengths. The root-mean-square value of beam wandering is insensitive to the variation of source correlation length, and less aperture averaging occurs when the laser source becomes less coherent. Additionally, from the point of view of beam wandering, the SC laser has no advantage over the pump laser. Although the pump laser can bring about a bigger aperture average, the SC laser has a lower scintillation which may be due to the multiple wavelength homogenization effects on intensity fluctuations. This would be the most important virtue of the SC laser that can be utilized to improve the performance of laser engineering.
Local dynamical characteristics of Bessel beams upon reflection near the Brewster angle*
Authors: Cui Zhi-Wei , Guo Shen-Yan , Hui Yuan-Fei , Wang Ju , Han Yi-Ping
Published: December 2020

We analytically and numerically study the local dynamical characteristics of the Bessel beams reflected from an air—glass interface near the Brewster angle. A Taylor series expansion based on the angular spectrum component is applied to correct the reflection coefficients near the Brewster angle. Using a hybrid angular spectrum representation and vector potential method, the explicit expressions for the electric and magnetic field components of the reflected Bessel beams are derived analytically under paraxial approximation. The local energy, momentum, spin, and orbital angular momentum of the Bessel beams upon reflection near the Brewster angle are examined numerically by utilizing a canonical approach. Numerical simulation results show that the properties of these dynamical quantities for the Bessel beams near Brewster angle incidence change abruptly, and are significantly affected by their topological charge, half-cone angle, and polarization state. The present study has its importance in understanding the dynamical aspects of optical beams with vortex structure and diffraction-free nature during the reflection process.
Characteristics and mechanisms of subthreshold voltage hysteresis in 4H-SiC MOSFETs*
Authors: Chen Xi-Ming , Shi Bang-Bing , Li Xuan , Fan Huai-Yun , Li Chen-Zhan , Deng Xiao-Chuan , Luo Hai-Hui , Wu Yu-Dong , Zhang Bo
Published: December 2020

In order to investigate the characteristics and mechanisms of subthreshold voltage hysteresis (ΔV
th,sub) of 4H-SiC metal–oxide–semiconductor field-effect transistors (MOSFETs), 4H-SiC planar and trench MOSFETs and corresponding P-type planar and trench metal–oxide-semiconductor (MOS) capacitors are fabricated and characterized. Compared with planar MOSFEF, the trench MOSFET shows hardly larger ΔV
th,sub in wide temperature range from 25 °C to 300 °C. When operating temperature range is from 25 °C to 300 °C, the off-state negative V
gs of planar and trench MOSFETs should be safely above –4 V and –2 V, respectively, to alleviate the effect of ΔV
th,sub on the normal operation. With the help of P-type planar and trench MOS capacitors, it is confirmed that the obvious ΔV
th,sub of 4H-SiC MOSFET originates from the high density of the hole interface traps between intrinsic Fermi energy level (E
i) and valence band (E
v). The maximum ΔV
th,sub of trench MOSFET is about twelve times larger than that of planar MOSFET, owing to higher density of interface states (D
it) between E
i and E
v. These research results will be very helpful for the application of 4H-SiC MOSFET and the improvement of ΔV
th,sub of 4H-SiC MOSFET, especially in 4H-SiC trench MOSFET.
Preparation of AlN film grown on sputter-deposited and annealed AlN buffer layer via HVPE*
Authors: Li Di-Di , Chen Jing-Jing , Su Xu-Jun , Huang Jun , Niu Mu-Tong , Xu Jin-Tong , Xu Ke
Published: December 2020

AlN films grown on sputter-deposited and annealed AlN buffer layer by high temperature hydride vapor phase epitaxy (HVPE) have been fabricated and structurally characterized. The crystalline quality and surface morphology of as-grown AlN films with various V/III ratios were studied and compared. The XRD results showed that the crystalline quality of the AlN film could be optimized when the growth V/III ratio was 150. At the same time, the full width at half-maximum (FWHM) values of (0002)- and (

10

1
¯

2

)-plane were 64 arcsec and 648 arcsec, respectively. As revealed by AFM, the AlN films grown with higher V/III ratios of 150 and 300 exhibited apparent hillock-like surface structure due to the low density of screw threading dislocation (TD). The defects microstructure and strain field around the HVPE-AlN/sputtered-AlN/sapphire interfaces have been investigated by transmission electron microscopy (TEM) technique combined with geometric phase analysis (GPA). It was found that the screw TDs within AlN films intend to turn into loops or half-loops after originating from the AlN/sapphire interface, while the edge ones would bend first and then reacted with others within a region of 400 nm above the interface. Consequently, part of the edge TDs propagated to the surface vertically. The GPA analysis indicated that the voids extending from sapphire to HVPE-AlN layer were beneficial to relax the interfacial strain of the best quality AlN film grown with a V/III ratio of 150.
Super-strong interactions between multivalent anions and graphene*
Authors: Liu Xing , Shi Guosheng
Published: December 2020

Based on the density functional theory (DFT) calculations, we showed that the interactions between different valence anions (

PO

4

3
−

,

CH

3

PO

4

2
−

,

(

CH

3

)

2

PO

4
−

) and graphene significantly increased as the valence of anion increased from negative monovalence to negative trivalence. The adsorption energy of

(

CH

3

)

2

PO

4
−

on the electron-rich graphene flake (C84H24) is −8.3 kcal/mol. The adsorption energy of

CH

3

PO

4

2
−

on the electron-rich graphene flake (C84H24) is –48.0 kcal/mol, which is about six times that of

(

CH

3

)

2

PO

4
−

adsorption on electron-rich graphene flake (C84H24) and is even much larger than that of

CO

3

2
−

adsorption on electron-deficient aromatic ring C6F6 (–28.4 kcal/mol). The adsorption energy of

PO

4

3
−

on the electron-rich graphene flake (C84H24) is –159.2 kcal/mol, which is about 20 times that of

(

CH

3

)

2

PO

4
−

adsorption on the graphene flake (C84H24). The super-strong adsorption energy is mainly attributed to the orbital interactions between multivalent anions and graphene. This work provides new insights for understanding the interaction between multivalent anions and π–electron-rich carbon-based nanomaterials and is helpful for the design of graphene-based DNA biosensor.
Interannual variability on methane emissions in monsoon Asia derived from GOSAT and surface observations
Authors: Wang Fenjuan , Maksyutov Shamil , Janardanan Rajesh , Tsuruta Aki , Ito Akihiko , Morino Isamu , Yoshida Yukio , Tohjima Yasunori , Kaiser Johannes W , Janssens-Maenhout Greet , Lan Xin , Mammarella Ivan , Lavric Jost V , Matsunaga Tsuneo
Published: December 2020

In Asia, much effort is put into reducing methane (CH4) emissions due to the region’s contribution to the recent rapid global atmospheric CH4 concentration growth. Accurate quantification of Asia’s CH4 budgets is critical for conducting global stocktake and achieving the long-term temperature goal of the Paris Agreement. In this study, we present top-down estimates of CH4 emissions from 2009 to 2018 deduced from atmospheric observations from surface network and GOSAT satellite with the high-resolution global inverse model NIES-TM-FLEXPART-VAR. The optimized average CH4 budgets are 63.40 ± 10.52 Tg y−1 from East Asia (EA), 45.20 ± 6.22 Tg y−1 from Southeast Asia (SEA), and 64.35 ± 9.28 Tg y−1 from South Asia (SA) within the 10 years. We analyzed two 5 years CH4 emission budgets for three subregions and 13 top-emitting countries with an emission budget larger than 1 Tg y−1, and interannual variabilities for these subregions. Statistically significant increasing trends in emissions are found in EA with a lower emission growth rate during 2014–2018 compared to that during 2009–2013, while trends in SEA are not significant. In contrast to the prior emission, the posterior emission shows a significant decreasing trend in SA. The flux decrease is associated with the transition from strong La Ninña (2010–2011) to strong El Ninño (2015–2016) events, which modulate the surface air temperature and rainfall patterns. The interannual variability in CH4 flux anomalies was larger in SA compared to EA and SEA. The Southern Oscillation Index correlates strongly with interannual CH4 flux anomalies for SA. Our findings suggest that the interannual variability in the total CH4 flux is dominated by climate variability in SA. The contribution of climate variability driving interannual variability in natural and anthropogenic CH4 emissions should be further quantified, especially for tropical countries. Accounting for climate variability may be necessary to improve anthropogenic emission inventories.
Contact network models matching the dynamics of the COVID-19 spreading
Authors: Medo Matúš
Published: December 2020

We study the epidemic spreading on spatial networks where the probability that two nodes are connected decays with their distance as a power law. As the exponent of the distance dependence grows, model networks smoothly transition from the random network limit to the regular lattice limit. We show that despite keeping the average number of contacts constant, the increasing exponent hampers the epidemic spreading by making long-distance connections less frequent. The spreading dynamics is influenced by the distance-dependence exponent as well and changes from exponential growth to power-law growth. The observed power-law growth is compatible with recent analyses of empirical data on the spreading of COVID-19 in numerous countries.
Remarks on dispersion-improved shallow water equations with uneven bottom
Authors: Clamond Didier
Published: December 2020

It is shown that asymptotically consistent modifications of (Boussinesq-like) shallow water approximations, in order to improve their dispersive properties, can fail for uneven bottoms (i.e., the dispersion is actually not improved). It is also shown that these modifications can lead to ill-posed equations when the water depth is not constant. These drawbacks are illustrated with the (fully nonlinear, weakly dispersive) Serre equations. We also derive asymptotically consistent, well-posed, modified Serre equations with improved dispersive properties for constant slopes of the bottom.
Generalised expression of the noise figure of phase sensitive amplifiers for an arbitrary number of modes
Authors: Bouasria Yousra , Chatterjee Debanuj , Goldfarb Fabienne , Hassouni Yassine , Bretenaker Fabien
Published: December 2020

Phase sensitive amplifiers (PSA), contrary to usual phase insensitive amplifiers (PIA), are in principle capable to achieve noiseless amplification, i.e. exhibit a quantum-limited noise figure (NF) of 0 db. When implemented using four-wave mixing (FWM) in a non-linear fibre, extra waves can be generated by undesired FWM processes, which may introduce extra input ports for vacuum fluctuations, thus potentially degrading the NF. In this situation, we give here a general analytical quantum derivation of the PSA NF, valid for an arbitrary number of nonlinearly coupled modes. This expression is usable as soon as a linear input-output relation can be found for the annihilation and creation operators of the involved modes. It predicts that the noise level depends on the number of interacting waves. We illustrate the usefulness of this expression in the case of six waves, corresponding to four interacting quantum modes. In this example the signal NF is degraded by 0.4 db, compared to 10 db obtained for PIA operation of the same scheme.
Automated measurements of morphological parameters of muscles and tendons
Authors: Jabbar Shaima Ibraheem , Day Charles , Chadwick Edward
Published: December 2020

Capturing accurate representations of musculoskeletal system morphology is a core aspect of musculoskeletal modelling of the upper limb. Measurements of important geometric parameters such as the thickness of muscles and tendons are key descriptors of the underlying morphology. Though the measurement of those parameters can be estimated manually using cadaveric measurements, this is not an appropriate technique for constructing a personalised musculoskeletal model for an individual. Therefore, this work proposes and applies a novel method for evaluating the geometric parameters of the upper extremity based on automated ultrasound image analysis. The proposed algorithm involves advanced techniques from artificial intelligence and image processing to outline the necessary details of the musculoskeletal morphology from appropriately enhanced ultrasound images. The ultrasound images were collected from 25 healthy volunteers from different parts of upper limb. The results were compared with measurements of a manual evaluation. Our results showed that the average discrepancy between the manual and automatic measures of triceps thickness is 0.115 mm. This represents improved accuracy compared to several current approaches.
Mg
x
Zn1−x
O contact to CuGa3Se5 absorber for photovoltaic and photoelectrochemical devices
Authors: Khan Imran S , Muzzillo Christopher P , Perkins Craig L , Norman Andrew G , Young James L , Gaillard Nicolas , Zakutayev Andriy
Published: December 2020

CuGa3Se5 is a promising candidate material with wide band gap for top cells in tandem photovoltaic and photoelectrochemical (PEC) devices. However, traditional CdS contact layers used with other chalcopyrite absorbers are not suitable for CuGa3Se5 due to the higher position of its conduction band (CB) minimum. Mg
x
Zn1−

x
O (MZO) is a transparent oxide with adjustable band gap and CB position as a function of magnesium composition, but its direct application is hindered by CuGa3Se5 surface oxidation. Here, MZO is investigated as a contact (n-type ‘buffer’ or ‘window’) material to CuGa3Se5 absorbers pretreated in Cd2+ solution, and an onset potential close to 1 V vs reversible hydrogen electrode in 10 mM hexaammineruthenium (III) chloride electrolyte is demonstrated. The Cd2+ surface treatment changes the chemical composition and electronic structure of the CuGa3Se5 surface, as demonstrated by photoelectron spectroscopy measurements. The performance of CuGa3Se5 absorber with Cd2+ treated surface in the solid-state test structure depends on the Zn/Mg ratio in the MZO layer. The measured open circuit voltage of 925 mV is promising for tandem PEC water splitting with CuGa3Se5/MZO top cells.
Pathways to help-seeking for sexual difficulties in older adults: qualitative findings from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)
Authors: Hinchliff Sharron , Lewis Ruth , Wellings Kaye , Datta Jessica , Mitchell Kirstin
Published: December 2020

Background

Older adults are at an increased risk of sexual difficulties due to ageing and chronic health conditions. While they experience barriers to seeking and receiving help for sexual difficulties there is a dearth of research about the help-seeking journey.

Objective

To explore decision-making in context; particularly, the reasons why older adults do, or do not, seek help for sexual difficulties.

Methods

Semi-structured interviews were conducted with 11 men and 12 women aged 58–75 who reported having a health condition, disability or medication that had affected their sex life in the last year. Participants were part of the third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3). Data were analysed thematically.

Results

Help-seeking was rarely a predictable or linear process. Participants tended to wait and see if the sexual difficulty got better on its own or improved as a result of lifestyle changes. An often-lengthy period of thinking, researching and planning could end with a decision to seek professional help, to not seek help, or do nothing for now. A significant barrier was concern about the interaction of medicines prescribed for the sexual difficulty with those already taken for chronic health conditions. Patient fear of not being taken seriously and doctor reticence to ask thwarted potential conversations. Help-seeking journeys often ended without resolution, even when professional help was sought.

Conclusions

To give patients and practitioners permission to raise the topic, suggestions include providing patients with a pre-consultation card which lists topics they would like to talk about, including sexual issues.
Are you my baby? Testing whether paternity affects behavior of cobreeder male acorn woodpeckers
Authors: Koenig Walter D , Prinz Anna C B , Haydock Joseph , Dugdale Hannah L , Walters Eric L
Published: December 2020

Natural selection is expected to favor males that invest more in offspring they sire. We investigated the relationship between paternity and male behavior in the acorn woodpecker (Melanerpes formicivorus), a cooperative breeder that lives in family groups including offspring that remain on their natal territory, sometimes for years, and cobreeders of both sexes. Regardless of group composition, only one communal nest is attended at a time. Whereas cobreeding females share maternity equally, one male usually sires the majority of young in the group’s communal nest. Copulations are rarely observed, and thus it has not been possible to link paternity to sexual behavior. There were no differences among cobreeder males that did or did not sire young in their propensity to roost in the nest cavity at night. However, cobreeder males that attended females continuously prior to egg-laying were more likely to successfully sire young than males that did not, and the relative share of feeding visits and time spent at the subsequent nest were positively related to a male’s realized paternity. These differences in male behavior were partly due to differences among males and partly to plasticity in male behavior covarying with paternity share. Feedings by males successfully siring young also involved a larger proportion of nutritionally valuable insect prey. Males are aware of their paternity success, apparently because of their relative access to females prior to egg laying, and provide more paternal care at nests in which they are more likely to have sired young.
ChemGenerator: a web server for generating potential ligands for specific targets
Authors: Yang Jing , Hou Ling , Liu Kun-Meng , He Wen-Bin , Cai Yong , Yang Feng-Qing , Hu Yuan-Jia
Published: December 2020

In drug discovery, one of the most important tasks is to find novel and biologically active molecules. Given that only a tip of iceberg of drugs was founded in nearly one-century’s experimental exploration, it shows great significance to use in silico methods to expand chemical database and profile drug-target linkages. In this study, a web server named ChemGenerator was proposed to generate novel activates for specific targets based on users’ input. The ChemGenerator relies on an autoencoder-based algorithm of Recurrent Neural Networks with Long Short-Term Memory by training of 7 million of molecular Simplified Molecular-Input Line-Entry System as the basic model, and further develops target guided generation by transfer learning. As results, ChemGenerator gains lower loss (<0.01) than existing reference model (0.2~0.4) and shows good performance in the case of Epidermal Growth Factor Receptor. Meanwhile, ChemGenerator is now freely accessible to the public by http://smiles.tcmobile.org. In proportion to endless molecular enumeration and time-consuming expensive experiments, this work demonstrates an efficient alternative way for the first virtual screening in drug discovery.
BiCoN: network-constrained biclustering of patients and omics data
Authors: Lazareva Olga , Canzar Stefan , Yuan Kevin , Baumbach Jan , Blumenthal David B , Tieri Paolo , Kacprowski Tim , List Markus
Published: December 2020

Motivation

Unsupervised learning approaches are frequently used to stratify patients into clinically relevant subgroups and to identify biomarkers such as disease-associated genes. However, clustering and biclustering techniques are oblivious to the functional relationship of genes and are thus not ideally suited to pinpoint molecular mechanisms along with patient subgroups.

Results

We developed the network-constrained biclustering approach Biclustering Constrained by Networks (BiCoN) which (i) restricts biclusters to functionally related genes connected in molecular interaction networks and (ii) maximizes the difference in gene expression between two subgroups of patients. This allows BiCoN to simultaneously pinpoint molecular mechanisms responsible for the patient grouping. Network-constrained clustering of genes makes BiCoN more robust to noise and batch effects than typical clustering and biclustering methods. BiCoN can faithfully reproduce known disease subtypes as well as novel, clinically relevant patient subgroups, as we could demonstrate using breast and lung cancer datasets. In summary, BiCoN is a novel systems medicine tool that combines several heuristic optimization strategies for robust disease mechanism extraction. BiCoN is well-documented and freely available as a python package or a web interface.

Availability and implementation

PyPI package: https://pypi.org/project/bicon.

Web interface

https://exbio.wzw.tum.de/bicon.

Supplementary information

Supplementary data are available at Bioinformatics online.
Teaching an Old Shell New Tricks: Extracting DNA from Current, Historical, and Ancient Mollusk Shells
Authors: Martin Kelly R , Waits Lisette P , Parent Christine E
Published: December 2020

The use of unconventional DNA sources has increased because the acquisition of traditional samples can be invasive, destructive, or impossible. Mollusks are one group for which novel genetic sources are crucial, but methodology remains relatively undeveloped. Many species are important ecologically and in aquaculture production. However, mollusks have the highest number of extinctions of any taxonomic group. Traditionally, mollusk shell material was used for morphological research and only recently has been used in DNA studies. In the present article, we review the studies in which shell DNA was extracted and found that effective procedures consider taxon-specific biological characteristics, environmental conditions, laboratory methods, and the study objectives. Importantly, these factors cannot be considered in isolation because of their fundamental, sometimes reciprocal, relationships and influence in the long-term preservation and recovery of shell DNA. Successful recovery of shell DNA can facilitate research on pressing ecological and evolutionary questions and inform conservation strategies to protect molluscan diversity.
Rapid and Sensitive LC-MS/MS Method for Simultaneous Determination of Three First-Line Oral Antituberculosis Drug in Plasma
Authors: Han Fei , Li Weiwei , Jin Yi , Wang Fang , Yuan Bo , Xu Haiyan
Published: December 2020

A bioanalytical method for simultaneous quantification of isoniazid (INH), pyrazinamide (PZA) and ethambutol (EMB) in plasma was developed and validated using high-performance liquid chromatography with tandem mass spectrometry. After extracted by protein precipitation with acetonitrile, the analytes were separated on a Waters XBridge Amide column by isocratic elution with acetonitrile and 5 mM ammonium acetate solution containing 0.3% formic acid (77:23, v/v) at a flow rate of 0.5 mL/min. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with an electrospray ionization source in positive mode by monitoring the selected ion transitions at m/z 205.2 → 116.1, m/z 137.9 → 121.2, m/z 124.3 → 78.9 and m/z 213.1 → 122.4 for EMB, INH, PZA and EMB-d8 Internal standard (IS), respectively. The calibration curves were linear over the range of 0.0125–2.00 μg/mL for EMB, 0.0625–10.0 μg/mL for INH and 0.250–40.0 μg/mL for PZA. Neither cross-analytes inter-conversion nor matrix effects were observed. The intra- and inter-assay precision (%RSD) values were within 8.80%, and accuracy (%RE) ranged from −11.13 to 13.49%, indicating that the precision and accuracy were well within the acceptable limits of variation. The method would be helpful for analysis of EMB, INH and PZA in plasma samples from clinical pharmacokinetics and therapeutic drug monitoring.
Channel Estimation for Millimeter Wave Massive MIMO System: Proposed Hybrid Optimization with Heuristic-Enabled Precoding and Combining
Authors: Srinivasa Rao Y , Madhu R
Published: December 2020

In multiple-input multiple-output (MIMO), millimeter wave (mmWave) is considered as a promising technology for advanced communication over wireless networks due to its rich frequency spectral resources. However, recognizing the mmWave in MIMO remains a complex task that faces the issues like increased propagation loss. Therefore, this paper proposes a new optimization-assisted estimation algorithm to estimate the mmWave channel parameters. The channel estimation and hybrid precoding performance on mmWave massive MIMO system are proposed by adopting optimization process in the codebook design principles. In fact, the existing works have performed uniform distribution of azimuth angles in the codebook design, whereas the proposed work evaluates it as a single objective optimization problem without excluding the angle characteristics. In order to solve the mentioned optimization problem, dragonfly-evaluated gray wolf optimization (DA-GWO) model is introduced that hybridizes the concepts of dragonfly algorithm and GWO, respectively. Finally, the performance of proposed work is compared and validated over other state-of-the-art models with respect to channel state information and error measures. Accordingly, from the analysis, the proposed DA-GWO model concerning (64, 64) combination for 400th channel bandwidth is 80% and 95.53% superior to adaptive channel estimation and projected gradient factorization algorithms.