bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis on teacher teaching evaluation system based on clustering constant modulus
Authors: Lv Jiangyi , Jiang Cherry , Gan Zhiwang
Published: May 2022

It is compiled by referring to some dimensions of cartel 16 personality factors questionnaire (16PF) and combined with the current situation of teachers in vocational colleges. Six dimensions are designed, which are communication and expression, innovation, persistence, manual operation, teachers’ professional identity and intelligence. The clustering algorithm is used to simulate and analyze the data system and establish the big data norm. In addition to describing the whole from the data of centralized trend and discrete trend, it can also describe the position of each individual score in the whole. Here, the concept of overall distribution is used to describe the overall data state by presenting the distribution diagram.
How to promote the class engagement of graduate students in seminar teaching: An empirical research
Authors: Liu Yexin , Gao Pengbin , Wu Weiwei
Published: May 2022

Student engagement is of critical importance because it can help students gain more knowledge from the course. This paper investigates how to improve student engagement of graduate students in seminar teaching, and the results show that student self-efficacy, classmate support, and teacher support have significant positive effects on student engagement. These findings highlight the value of self-efficacy, classmate support, and teacher support. Therefore, college should take measures to promote self-efficacy, classmate support, and teacher support.
Who and which regions are at high risk of returning to poverty during the COVID-19 pandemic?
Authors: Ge Yong , Liu Mengxiao , Hu Shan , Wang Daoping , Wang Jinfeng , Wang Xiaolin , Qader Sarchil , Cleary Eimear , Tatem Andrew J. , Lai Shengjie
Published: May 2022

Pandemics such as COVID-19 and their induced lockdowns/travel restrictions have a significant impact on people’s lives, especially for lower-income groups who lack savings and rely heavily on mobility to fulfill their daily needs. Taking the COVID-19 pandemic as an example, this study analysed the risk of returning to poverty for low-income households in Hubei Province in China as a result of the COVID-19 lockdown. Employing a dataset including information on 78,931 government-identified poor households, three scenarios were analysed in an attempt to identify who is at high risk of returning to poverty, where they are located, and how the various risk factors influence their potential return to poverty. The results showed that the percentage of households at high risk of returning to poverty (falling below the poverty line) increased from 5.6% to 22% due to a 3-month lockdown. This vulnerable group tended to have a single source of income, shorter working hours, and more family members. Towns at high risk (more than 2% of households returning to poverty) doubled (from 27.3% to 46.9%) and were mainly located near railway stations; an average decrease of 10–50 km in the distance to the nearest railway station increased the risk from 1.8% to 9%. These findings, which were supported by the representativeness of the sample and a variety of robustness tests, provide new information for policymakers tasked with protecting vulnerable groups at high risk of returning to poverty and alleviating the significant socio-economic consequences of future pandemics.
Nobel discoveries pave the way for accurate climate modeling
Authors: Ikenson By Ben
Published: May 2022

Three 2021 Nobel Prize Winners bring better understanding of climate change and ability for predicting its impacts
Analysis of a stochastic logistic model with diffusion and Ornstein–Uhlenbeck process
Authors: Liu Qun , Jiang Daqing
Published: May 2022

In this paper, we develop and study a stochastic logistic model by incorporating diffusion and two Ornstein–Uhlenbeck processes, which is a stochastic non-autonomous system. We first show the existence and uniqueness of the global solution of the system with any initial value. After that, we study the pth moment boundedness, asymptotic pathwise estimation, asymptotic behavior, and global attractivity of the solutions of the stochastic system in turn. Moreover, we establish sufficient criteria for the existence and uniqueness of a stationary distribution of positive solutions of the stochastic system with the help of Lyapunov function methods. It is worth mentioning that we derive the exact expression of the local probability density for the stochastic system by solving the relevant four-dimensional Fokker–Planck equation. We find that the smaller intensity of volatility or the bigger speed of reversion is helpful for preserving the biodiversity of the species. Finally, numerical simulations are performed to support our analytical findings.
Gas chromatograph calibration of gas mixtures using a versatile precision volumetric apparatus
Authors: Raal J. David , Nelson Wayne Michael
Published: May 2022

A compact, volumetric apparatus was developed for accurate automated preparation of standard gas and gas–liquid mixtures for gas chromatograph detector calibration, with accuracies comparable to those from gravimetric or Coriolis flow methods. The method developed by the principal author is not an adaptation or extension of any other apparatus or technology, and measurements involve only stepper motor steps, temperature, and pressure ratios. Mixture preparation is accomplished via the displacement of gas between chambers in a highly uniform cylinder, separated by a movable piston. Piston movement, with piston end rods of exactly equal diameter, ensures that there is no change in interior volume, and the volume of gas displaced from the bottom into the top compartment is exactly proportional to the piston travel measured to within 10 μm. The apparatus, operation, and previously unpublished measurements on common refinery gas mixtures over large concentration ranges are described in detail. These confirmed the accuracy and versatility of the apparatus and also the principle of no pressure change during mixture preparation, from sensitive pressure measurements. Conservative expanded uncertainties in prepared mixture mole fraction ranged from 0.001 to 0.002 over extended composition ranges. Absolute average deviations for the detector response factor for the mixtures ranged from 0.001 to 0.002. An exact new mathematical solution procedure permits the use of impure “pure” gases without loss of accuracy and can be applied to other procedures for standard gas mixture preparation. An exact expression is listed for determining “pure” gas purity.
Study on bandgap of a novel phononic crystal with low-frequency sound insulation
Authors: Han Dong-Hai , Zhang Guang-Jun , Zhao Jing-Bo , Yao Hong
Published: May 2022

To solve the problem of low-frequency noise in the environment, a two-dimensional Helmholtz-type phononic crystal with a labyrinth tube was designed in the paper. First, the low-frequency band structure was calculated by the finite element method (FEM) and transfer matrix method (TMM). Second, the bandgap formation was analyzed by using an acoustic pressure field, and the “spring-oscillator” equivalent model of the structure was established. Finally, the influences of structural parameters on the first bandgap were investigated. Results show that there are four bandgaps in the frequency range of 0–300 Hz, and the lower limit of the first bandgap can be as low as 12.15 Hz, which improves the low-frequency sound insulation ability of phononic crystals of the same size. The calculation results of the two methods (FEM and TMM) are basically consistent. Research on the influencing factors of the bandgap shows that the increase in the length of the tube will reduce the upper and lower limits of the bandgap and narrow the bandgap width. With the increase of the lattice constant, the upper limit of the bandgap decreases, while the lower limit of the bandgap remains unchanged. The design provides a new method to solve the problem of low-frequency noise reduction.
Noninvasive electroencephalogram sensors based on all-solution-processed trapezoidal electrode array
Authors: Kang Byeong-Cheol , Ha Tae-Jun
Published: May 2022

Conventional wet electrodes, such as a silver/silver chloride electrode, are limited for electroencephalogram (EEG) sensors directly attached to the scalp with existing hair due to their incomplete contact and increased impedance. In this study, an all-solution-processed trapezoidal electrode array is demonstrated for highly sensitive and reliable detection of EEG signals even when in direct contact with the scalp. The proposed noninvasive EEG sensors based on nanocomposites consisting of single-wall carbon nanotube random networks incorporated into a gelatin matrix exhibited a relatively low contact impedance of 11.16 × 102 Ω and a high sensitivity of 14.81 dB regardless of existing hair for real-time EEG recording without conductive gels or electrolytes. Furthermore, the origin of such advances induced by the soft and conductive electrode array is investigated by analyzing the effective contact area and signal-to-noise ratio on different scalp positions from 20 different subjects. A trapezoidal EEG electrode penetrates the dense hair and bypasses the hair shaft owing to its deformable shape induced by the soft and flexible nanocomposite film.
Perspectives on the importance of complex systems in understanding our climate and climate change—The Nobel Prize in Physics 2021
Authors: Gupta Shraddha , Mastrantonas Nikolaos , Masoller Cristina , Kurths Jürgen
Published: May 2022

The Nobel Prize in Physics 2021 was awarded to Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi for their “groundbreaking contributions to our understanding of complex systems,” including major advances in the understanding of our climate and climate change. In this Perspective article, we review their key contributions and discuss their relevance in relation to the present understanding of our climate. We conclude by outlining some promising research directions and open questions in climate science.
Motionless synthesis and scanning of lattice light sheets with a single digital micromirror device
Authors: Zhao Qian , Tu Shijie , Sun Hongyu , Hoenders Bernhard J. , Cai Yangjian , Gong Lei
Published: May 2022

Lattice light sheet microscopy is uniquely positioned in biomedical imaging modalities due to its superior performance in temporal-spatial resolution and low phototoxicity. However, the imaging system is commonly complicated because producing lattice light sheets involves mechanical scanning and precise alignment. In this Letter, we present an experimental scheme for motionless synthesis and scanning of lattice light sheets using a single digital micromirror device. By fully exploiting its ability of complex amplitude modulation and fast switching, single-shot construction of a uniform lattice light sheet can be achieved by digital dithering. In particular, fast scanning of the lattice light sheet in the depth direction is also realized without any mechanical motion. As a proof of concept, various lattice light sheets are generated and characterized in the experiments. Our work is expected to benefit the development of a compact and low-price lattice light-sheet microscope for biomedical imaging.
Formation and detection of metastable formic acid in a supersonic expansion: High resolution infrared spectroscopy of the jet-cooled cis-HCOOH conformer
Authors: Doney Kirstin D. , Kortyna Andrew , Chan Ya-Chu , Nesbitt David J.
Published: May 2022

High-resolution direct absorption infrared spectra of metastable cis-formic acid (HCOOH) trapped in a cis-well resonance behind a 15 kcal/mol barrier are reported for the first time, with the energetically unstable conformer produced in a supersonic slit plasma expansion of trans-formic acid/H2 mixtures. We present a detailed high-resolution rovibrational analysis for cis-formic acid species in the OH stretch (ν1) fundamental, providing first precision vibrational band origin, rotational constants, and term values, which in conjunction with ab initio calculations at the couple-cluster with single, double, and perturbative triple [CCSD(T)]/ANOn (n = 0, 1, 2) level support the experimental assignments and establish critical points on the potential energy surface for internal rotor trans-to-cis isomerization. Relative intensities for a- and b-type transitions observed in the spectra permit the transition dipole moment components to be determined in the body fixed frame and prove to be in good agreement with ab initio CCSD(T) theoretical estimates but in poor agreement with simple bond-dipole predictions. The observed signal dependence on H2 in the discharge suggests the presence of a novel H atom radical chemical mechanism for strongly endothermic “up-hill” internal rotor isomerization between trans- and cis-formic acid conformers.
The competition between the hydrodynamic instability from noise and magnetorotational instability in the Keplerian disks
Authors: Ghosh Subham , Mukhopadhyay Banibrata
Published: May 2022

We venture for the comparison between growth rates for magnetorotational instability (MRI) and hydrodynamics instability in the presence of an extra force in the local Keplerian accretion flow. The underlying model is described by the Orr–Sommerfeld and Squire equations in the presence of rotation, magnetic field, and an extra force, plausibly noise with a nonzero mean. We obtain MRI using the Wentzel–Kramers–Brillouin approximation without extra force for a purely vertical magnetic field and vertical wavevector of the perturbations. Expectedly, MRI is active within a range of magnetic field, which changes depending on the perturbation wavevector magnitude. Next, to check the effect of noise on the growth rates, a quartic dispersion relation has been obtained. Among those four solutions for the growth rate, the one that reduces to the MRI growth rate at the limit of vanishing mean of noise in the MRI active region of the magnetic field is mostly dominated by MRI. However, in the MRI inactive region, in the presence of noise, the solution turns out to be unstable, which is almost independent of the magnetic field. Another growth rate, which is almost complementary to the previous one, leads to stability at the limit of vanishing noise. The remaining two growth rates, which correspond to the hydrodynamical growth rates at the limit of the vanishing magnetic field, are completely different from the MRI growth rate. More interestingly, the latter growth rates are larger than that of the MRI. If we consider viscosity, the growth rates decrease depending on the Reynolds number.
Structural control of fibrin bioactivity by mechanical deformation
Authors: Kumar Sachin , Wang Yujen , Hedayati Mohammadhasan , Fleissner Frederik , Rausch Manuel K. , Parekh Sapun H.
Published: May 2022

Significance

Fibrin plays a vital role in biology as the fibrous network that stabilizes blood clots and also through interaction with numerous blood components. While much is known about fibrin mechanics, comparatively little is known about how fibrin’s mechanics influence its biochemistry. We show that structural changes in fibrin under mechanical tension reduces binding of tissue plasminogen activator, an enzyme that initiates lysis. Furthermore, these structural transitions also led to decreased platelet activation through suppressed binding between platelet integrins and fibrin. Our work shows that fibrin possesses an intrinsic mechano-chemical feedback loop that regulates its bioactivity via molecular structural rearrangements.
Thalamocortical axons regulate neurogenesis and laminar fates in the early sensory cortex
Authors: Monko Timothy , Rebertus Jaclyn , Stolley Jeff , Salton Stephen R. , Nakagawa Yasushi
Published: May 2022

Significance

This study addresses how the cerebral cortex is partitioned into specialized areas during development. Although both early embryonic patterning and postnatal synaptic input from sensory thalamic nuclei are known to be critical, early roles of thalamic axons in area-specific regulation of cortical neurogenesis are poorly understood. We examined this by developing a genetic mouse model in which thalamocortical projections fail to properly form during embryogenesis, and found these axons are required not only for an enhanced production of superficial layer neurons but also for promoting the layer 4 cell fate, a hallmark of the primary sensory cortex. These findings provide a mechanism by which thalamocortical axons complement the intrinsic programs of neurogenesis and early fate specification.
Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor
Authors: Shen Shiwei , Qin Tian , Gao Jingjing , Wen Chenhaoping , Wang Jinghui , Wang Wei , Li Jun , Luo Xuan , Lu Wenjian , Sun Yuping , Yan Shichao
Published: May 2022

Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation, but also is helpful for further understanding the heavy fermion superconductivity. Here we report a low-temperature and vector-magnetic-field scanning tunneling microscopy and spectroscopy study on a superconducting compound (4Hb-TaS2) with alternate stacking of 1T-TaS2 and 1H-TaS2 layers. We observe the quasi-two-dimensional superconductivity in the 1H-TaS2 layer with anisotropic response to the in-plane and out-of-plane magnetic fields. In the 1T-TaS2 layer, we detect the Kondo resonance peak that results from the Kondo screening of the unpaired electrons in the Star-of-David clusters. We also find that the intensity of the Kondo resonance peak is sensitive to its relative position with the Fermi level, and it can be significantly enhanced when it is further shifted towards the Fermi level by evaporating Pb atoms onto the 1T-TaS2 surface. Our results not only are important for fully understanding the electronic properties of 4Hb-TaS2, but also pave the way for creating tunable Kondo lattice in the superconducting van der Waals materials.
Low-thermal-budget n-type ohmic contacts for ultrathin Si/Ge superlattice materials
Authors: Zhang Di , Yuan Guodong , Zhao Shuai , Lu Jun , Luo Junwei
Published: May 2022

Thermal budget is a vital element of Si-based superlattice material processing. In this work, a novel n-type ohmic contact scheme with a low thermal budget process is developed by combining high-dose ion implantation and low-temperature alloying techniques. The optimized specific contact resistivity (ρ
c) is reduced to 6.18 × 10−3 Ω cm2 at a low thermal budget of 400 °C, and this is a result of the efficient low-temperature electrical activation of amorphous substances. It is indicated that both the high doping concentration and the formation of a NiSi(Ge) alloy phase contribute to the linear ohmic contact behavior. The ohmic contact resistance dependence on processing temperature is further revealed by a detailed Ni/Si(Ge)alloying model. A minimum ρ
c of 2.51 × 10−4 Ω cm2 is achieved at a thermal budget of 450 °C, which is related to the high bonding intensity at the metal–semiconductor interface. Note that this technique is compatible with standard Si-based CMOS process flows and can be applied in high-performance insulated-gate field-effect transistor (IGFET) fabrication. Furthermore, it is verified that the Si/Ge superlattice structures in our IGFETs can serve as an efficient potential barrier to constrain electrons.
Research on the influence of temperature on the sensing function of Faraday effect optical magnetic field sensor
Authors: Li Jiaxun , Wen Tao , Fan Xing , Chen Boyan , Jin Mingkai , Zhao Yi , Zhang Qiaogen , Chen Weijiang
Published: May 2022

The Faraday effect optical magnetic field sensor has broad application prospects in power systems, and the temperature stability of the sensor has always been the focus of research. Existing researches mostly focus on the influence of temperature on the Verdet constant of the magneto-optical material, but there are other temperature factors that are not taken into account, which limits the improvement of the temperature stability of the sensor. In this paper, the effect of magneto-optical crystal (TGG) temperature on the optical rotation coefficient and static operating point of the sensor’s sensing function was studied. It was found that the crystal temperature has a significant effect on the optical rotation coefficient and static operating point in the sensing function. The optical rotation coefficient and static operating point fluctuate periodically with the change of crystal temperature. Through the theoretical analysis of the influence mechanism of temperature, it was found that the interference of multiple reflected light in the magneto-optical crystal has a significant influence on the optical rotation coefficient and static operating point. The mechanism of temperature affecting the sensing function was proposed: temperature affects the phase of reflected light through thermo-optical effect and thermal expansion effect, changes the interference state of reflected light, and then affects the optical rotation coefficient and static operating point. Quantitative calculations were carried out on the influence of temperature using the theoretical model. The calculation results are in good agreement with the experimental data. This article provides a theoretical basis for the optimal design of such sensors.
A theoretical insight into phonon heat transport in graphene/biphenylene superlattice nanoribbons: a molecular dynamic study
Authors: Farzadian Omid , Dehaghani Maryam Zarghami , Kostas Konstantinos V , Mashhadzadeh Amin Hamed , Spitas Christos
Published: May 2022

Manipulating the thermal conductivity of nanomaterials is an efficacious approach to fabricate tailor-made nanodevices for thermoelectric applications. To this end, superlattice nanostructures can be used to achieve minimal thermal conductivity for the employed nanomaterials. Two-dimensional biphenylene is a recently-synthesized sp2-hybridized allotrope of carbon atoms that can be employed in superlattice nanostructures and therefore further investigation in this context is due. In this study, we first determined the thermal conductivity of biphenylene at 142.8 W mK−1 which is significantly lower than that of graphene. As a second step, we studied the effect of the superlattice period (

l

p

) on thermal conductivities of the employed graphene/biphenylene superlattice nanoribbons, using molecular dynamics simulations. We calculated a minimum thermal conductivity of 105.5 W mK−1 at

l

p

= 5.066 nm which indicates an achieved thermal conductivity reduction of approximately 97% and 26% when compared to pristine graphene and biphenylene, respectively. This superlattice period denotes the phonon coherent length at which the wave-like behavior of phonons starts prevailing over the particle-like behavior. Finally, the effects of temperature and temperature gradient on the thermal conductivity of superlattice were also investigated.
Investigation of hardware and software techniques to enhance the characteristics of focused ultrasound (FUS) spectra
Authors: Smith Michael , Khan Sonia , Curiel Laura
Published: May 2022

Objective. Microbubble cavitation generated by focused ultrasound (FUS) can induce safe blood-brain-barrier (BBB) opening allowing therapeutic drug passage. Spectral changes in the hydrophone sensor signal are currently used to distinguish stable cavitation from inertial cavitation that can damage the BBB. Gibbs’ ringing, peak intensity loss and peak width increase are well-known distortions evident when using the discrete Fourier transform (DFT) to transform data containing a few hundred points. We investigate overcoming the fact that FUS time signals (10 ms providing 312 500 points sampled at 32 ns intervals) can generate such sharp spectral peaks that variations in their DFT-related distortions can significantly impact the values of the key metrics used for cavitation characterization. Approach. We introduce low-pass filter hardware to improve how the analogue to digital convertor handles high-frequency noise components and the orders of magnitude differences between FUS harmonic intensities. We investigate the enhanced FUS spectral stability and resolution obtained from a new technique, physical sparsification (PH-SP), customized to the a-priori information that all key FUS components are harmonically related. Results are compared with standard DFT optimizations involving time data windowing and Fourier interpolation. Main results. A new simulation model showed peak intensity, widths and metrics modified by small changes in the transformed signal’s length when removing the noisy starting transient of the FUS hydrophone signal or following minor excitation frequency or sampling rate adjustments. 25%–60% area-under-the-curve changes occurred in phantom studies at different pressure levels. Spectral peak sharpness was best optimized and stabilized with PH-SP. Significance. Special FUS characteristics mean starting transients and minor variations in experimental procedures lead to significant changes in the spectral metrics used to monitor cavitation levels. Customizing PH-SP to these characteristics led to sharper, more stable spectra with the potential to track the impact of microbubble environment changes.
Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run: 1. Measurement of strain
Authors: James Stephen W , Kissinger Thomas , Weber Simone , Mullaney Kevin , Chehura Edmond , Pekmezci Huseyin H , Barrington James H , E Staines Stephen , Charrett Thomas O H , Lawson Nicholas J , Lone Mudassir , Atack Richard , Tatam Ralph P
Published: May 2022

Optical fibre strain and shape measurement sensors were deployed on a 5-m long rotor blade during a full-speed (rotation rate 6.6 Hz) helicopter ground run, with real-time data wirelessly streamed from rotor hub-mounted sensor interrogators. In Part 1 of a 2-part paper series, the strain sensing capabilities of the two optical fibre-based sensing techniques, optical fibre Bragg grating (FBG) and fibre segment interferometry (FSI), are compared, while Part 2 (Kissinger et al 2022 Smart Mater. Struct. accepted) specifically investigates the blade shape measurement based on the FSI approach. In part 1, the rotor hub-mounted instrumentation is described, and data on the dynamics of the blade obtained from a sequence of controlled pilot inputs are analysed both in the time and spectral domains. It is shown that this can provide insights into the aeroelastic properties of the blade. Noise standard deviations of 0.2 n

ϵ

/

Hz

and 30 n

ϵ

/

Hz

for the FSI and FBG-based sensing approaches, respectively, were observed over a strain range of 3500 µϵ.
Thermodynamic parameters of atomically thin superconductors derived from the upper critical field
Authors: Talantsev Evgeny F
Published: May 2022

The amplitude of the ground-state superconducting energy gap Δ(0) and relative jump in the electronic specific heat at the transition temperature

Δ

C

γ

T
c

are the primary fundamental parameters of any superconductor. Several well-established techniques are available for measuring these values in bulk samples. However, a limited number of techniques can be used to measure these parameters in atomically thin superconductors. Here, we propose a new approach for extracting Δ(0) and

Δ

C

γ

T
c

in atomically thin superconductors by utilizing the upper critical field data from perpendicular, B
c2,Δ(T) (when a magnetic field is applied perpendicular to the film surface) and parallel, B
c2,‖(T) (when a magnetic field is applied in the direction parallel to the film surface), external field directions. The deduced parameters for few-layer-thick Al, Sn, NbSe2, MoS2, magic angle twisted trilayer graphene, and WTe2 are well-matched values expected for strongly and moderately strongly coupled electron-phonon-mediated superconductors. In many reports, the enhancement of B
c2,‖(0) above the Pauli–Clogston–Chandrasekhar limiting field (i.e. magnetic field required to break the Cooper pair) in atomically thin superconductors has been explained based on the assumption of exotic pairing mechanisms, for instance, Ising-type pairing. Here, we explain the observed B
c2,‖(0) enhancement based on the geometrical enhancement factor that originates from the sample geometry. This approach does not assume the existence of novel exotic pairing mechanisms in atomically thin superconductors.
Resource speed limits: maximal rate of resource variation
Authors: Campaioli Francesco , Yu Chang-shui , Pollock Felix A , Modi Kavan
Published: May 2022

Recent advances in quantum resource theories have been driven by the fact that many quantum information protocols make use of different facets of the same physical features, e.g. entanglement, coherence, etc. Resource theories formalise the role of these important physical features in a given protocol. One question that remains open until now is: how quickly can a resource be generated or degraded? Using the toolkit of quantum speed limits we construct bounds on the minimum time required for a given resource to change by a fixed increment, which might be thought of as the power of said resource, i.e., the rate of resource variation. We show that the derived bounds are tight by considering several examples. Finally, we discuss some applications of our results, which include generalisations of thermodynamic work, heat, and power to any given resource, as well as fundamental bounds on the computation rate in leading quantum processing architectures.
Complete conversion between one and two photons in nonlinear waveguides: theory of dispersion engineering
Authors: Solntsev Alexander S , Batalov Sergey V , Langford Nathan K , Sukhorukov Andrey A
Published: May 2022

High-efficiency photon-pair production is a long-sought-after goal for many optical quantum technologies, and coherent photon conversion (CPC) processes are promising candidates for achieving this. We show theoretically how to control coherent conversion between a narrow-band pump photon and broadband photon pairs in nonlinear optical waveguides by tailoring frequency dispersion for broadband quantum frequency mixing. We reveal that complete deterministic conversion as well as pump-photon revival can be achieved at a finite propagation distance. We also find that high conversion efficiencies can be realised robustly over long propagation distances. These results demonstrate that dispersion engineering is a promising way to tune and optimise the CPC process.
Evaporation of dark matter from celestial bodies
Authors: Garani Raghuveer , Palomares-Ruiz Sergio
Published: May 2022

Scatterings of galactic dark matter (DM) particles with the constituents of celestial bodies could result in their accumulation within these objects. Nevertheless, the finite temperature of the medium sets a minimum mass, the evaporation mass, that DM particles must have in order to remain trapped. DM particles below this mass are very likely to scatter to speeds higher than the escape velocity, so they would be kicked out of the capturing object and escape. Here, we compute the DM evaporation mass for all spherical celestial bodies in hydrostatic equilibrium, spanning the mass range [10-10 - 102] M⊙, for constant scattering cross sections and s-wave annihilations. We illustrate the critical importance of the exponential tail of the evaporation rate, which has not always been appreciated in recent literature, and obtain a robust result: for the geometric value of the scattering cross section and for interactions with nucleons, at the local galactic position, the DM evaporation mass for all spherical celestial bodies in hydrostatic equilibrium is approximately given by Ec/Tχ
∼ 30, where Ec
is the escape energy of DM particles at the core of the object and Tχ
is their temperature. In that case, the minimum value of the DM evaporation mass is obtained for super-Jupiters and brown dwarfs, m
evap ≃ 0.7 GeV. For other values of the scattering cross section, the DM evaporation mass only varies by a factor smaller than three within the range 10-41 cm2 ≤ σp
≤ 10-31 cm2, where σp
is the spin-independent DM-nucleon scattering cross section. Its dependence on parameters such as the galactic DM density and velocity, or the scattering and annihilation cross sections is only logarithmic, and details on the density and temperature profiles of celestial bodies have also a small impact.
Double-balanced mixer based on monolayer graphene field-effect transistors
Authors: Wu Min , Hong Weida , Liu Guanyu , Zhang Jiejun , Tian Ziao , Zhang Miao
Published: May 2022

Graphene field-effect transistors (GFET) have attracted much attention in the radio frequency (RF) and microwave fields because of its extremely high carrier mobility. In this paper, a GFET with a gate length of 5 μm is fabricated through the van der Walls (vdW) transfer process, and then the existing large-signal GFET model is described, and the model is implemented in Verilog-A for analysis in RF and microwave circuits. Next a double-balanced mixer based on four GFETs is designed and analyzed in advanced design system (ADS) tools. Finally, the simulation results show that with the input of 300 and 280 MHz, the IIP3 of the mixed signal is 24.5 dBm.
Algorithm for optimization of methanol consumption in the «gas inhibitor pipeline-well-gathering system»
Authors: Proshutinskiy M S , Raupov I R , Brovin N M
Published: May 2022

The article proposes an algorithm of actions to optimize the consumption of methanol which is used as an inhibitor of hydrate formation in the process chain of oil and gas production. The proposed approach was developed in the process of analyzing the methanol supply system and planning measures to optimize it for the Eastern section of the Orenburg oil and gas condensate field. The algorithm consists of five sections which to a greater extent affect the efficiency of the inhibition system and are closely related to each other. These are data preparation, determination of equilibrium conditions of hydrate formation, calculation of methanol consumption rates, analysis of the inhibition system flexibility, operational control. The proposed solution in the form of an algorithm makes it possible to carry out a complex analysis of the hydrate formation prevention system, to determine the most optimal solutions to reduce the consumption of methanol.
Survey of knowledge and practice related health risks of mercury exposure among gold craft workers in Rappocini area, Makassar city
Authors: Rahmadani Nanang , Syafri Muhammad
Published: May 2022

Mercury (Hg) can cause acute and chronic intoxications in humans, such as damage to the central nervous system, lungs, and kidneys. Goldsmiths pose the risk of exposure to Hg through direct skin contact or inhalation of Hg vapor during the amalgam burning process. This study aims to assess the level of workers' knowledge regarding the risk of exposure to Hg and investigate the practice of preventing health risks from exposure to Hg in household-level gold-crafting activities. The study used a descriptive observational approach. The population of the study was 110 gold craftsmen in the Rapokkaling Village, Makassar City. The number of samples was 52 people determined by the purposive sampling technique. The data collection instruments included a structured questionnaire, camera, recorder, and field note. The results of the data analysis showed that the proportion of respondents with a sufficient level of knowledge was greater than that with a low level of knowledge (65.4% and 34.6%, respectively). On the other hand, the results of the observation showed that 100% of gold craft workers had unsecure work practices. Sufficient knowledge about the risks of exposure to Hg does not guarantee the discipline of implementing secure work practices including using personal protective equipment.
UV spectroscopy for discrimination of two arabica coffee cultivars in West Java Indonesia: a feasibility study
Authors: Yulia M , Ningtyas K R , Suharyatun S , Rahmawati W , Suhandy D
Published: May 2022

Arabica coffee variety is one of the key parameters that highly influence the cup quality of arabica coffee. The objective of this current research is to evaluate the possible application of UV spectroscopy for the discrimination of arabica coffee with different cultivars. Green beans from two arabica coffee cultivars (Coffea arabica) of Typica and Sigarar Utang were collected from the same origin in Papandayan mountain West Java, Indonesia. The samples were subjected to the same postharvest treatments (wet cherry processing method). All samples were roasted in medium roasting with 200°C for 16 minutes using a portable roasting machine. A total of 40 samples of Typica and Sigarar Utang were provided by weighing 1 gram of coffee powder (mesh 40) for each sample. The extraction of coffee samples was performed based on previously reported work. The UV-visible spectral data of aqueous coffee samples were acquired by using a benchtop of UV-vis spectrometer in the range of 190-1100 nm. The first two PCs (principal components) with 94% of CEV (cumulative explained variance) could be used to separate between the Typica and Sigarar Utang samples. The Typica samples were situated on the left of PC1 (PC1<0) and Sigarar Utang samples were on the right of PC1 (PC1>0). In the future, it is promising to apply UV spectroscopy for simple and reliable discrimination of arabica coffee cultivar.
Conditions for Successful Local Collective Action in Mangrove Forest Management: Some Evidences from Eastern Coastal Area of South Sulawesi, Indonesia
Authors: Suharti S , Darusman D , Nugroho B , Sundawati L
Published: May 2022

Resource management characterized by Common Pool Resources (CPRs) requires collective action for its sustainable management. CPRs with “rivalry” and “non-excludable” features face overexploitation problems because unlike the nature of pure public goods, the use of CPRs by one user will reduce the chances of other users taking advantage of it. This study aims to analyze the most appropriate local institutions and tenure arrangements for sustainable mangrove management in Eastern coast area of South Sulawesi, Indonesia. Data and information were collected through in-depth interviews involving key informants selected by using snow-ball method and continued by Focus Group Discussion. Design principles for sustainable management of common pool resources of Ostrom has been used in this study as an analytical framework which illustrate the structure of rules established and imposed by the local CPR’s institutions. The findings show that collective action in sustainable mangrove management can be achieved through accepted rules and agreements that are participatory formulated. The agreed norms and rules have enacted as a benchmark for collective action in maintaining mangrove and to enforce sanctions for violators. The success of the community in sustainable mangrove resources management is mainly supported by the existence of several prerequisites that facilitate collective action. It is necessary to strengthen regulations both at the local and higher level through socialization to the community along with the development of incentive and disincentives system.
Bioethanol production from seaweed solid waste biomass of agar processing
Authors: Winarni I , Uju  , Santoso J , Wibowo T
Published: May 2022

This paper describes about the potential application of renewable energy sources from biomass (seaweed waste) to replace fossil fuels combustion which produced CO2 emission and heavy metal pollution. The objective of the research is to utilize the seaweed solid waste from agar production industry for bioethanol feedstock. The enzymatic method was carried out for glucose production with the addition 1% of surfactant Tween 20 during the saccharification process of three kinds of substrate concentration (20, 25, 30% dw) and 10 FPU/g substrate for the cellulose concentration and usedS. cerevisaeas yeast in the fermentation process for bioethanol production. The result showed that the highest reducing sugar value (122.4 mg/mL) and 2.86% for the bioethanol content were from 30% dw treatment of substrate concentration of solid agar waste. Therefore, the waste from agar industry is a potential raw material to be used as biofuel and could reduce the heavy metal problems.
Farmers perceptions of paddy rice cultivation technology in Jakarta city
Authors: Ammatillah Chery Soraya , Sutardi Susi , Aminah Syarifah , Nurmalinda Dan
Published: May 2022

Rice cultivation technology from the IAARD has been introduced to several rice farmers in DKI Jakarta. The introduction carried out to optimize rice productivity amid all the limited urban agricultural resources. Farmers in urban areas have different characteristics. Easy access to information and access to farming locations should influence farmers' perceptions of the technology introduced. Therefore, this research aims to determine the characteristics of rice farmers in Jakarta and to find out the farmers' perceptions of introducing rice cultivation technology. The study was conducted in DKI Jakarta involving 25 farmers. Qualitative descriptive analysis was used to determine the characteristics of rice farmers in Jakarta. Quantitative analysis was used to determine perception of paddy rice cultivation technology. Perception analysis with a Likert scale approach was used to determine farmers' perceptions. The results show that although most of the rice farmers in Jakarta are not owners of cultivated rice fields and have limited land in various aspects, they have good accessibility. The analysis results also show that most respondent farmers have good/positive perceptions of introducing rice cultivation technology.
On dynamics of elliptic solitons in lossy optical fibers
Authors: Nfor Nkeh Oma , Jaja Mangeh Elsie
Published: May 2022

By exploiting the theory of electromagnetic waves from Maxwell’s equations, the damped nonlinear Schrödinger (DNLS) equation is shown to govern the evolution of nonlinear periodic optical signals in a lossy optical fiber. These optical periodic pulses are mainly generated by the classical process of modulational instability (MI) in which nonlinearity is balanced by chromatic dispersion in the anomalous regime, with the linear loss generally suppressing the existence of soliton trains during propagation down the lossy fiber. When the periodic optical wave trains are subjected to weak external perturbations, this leads to the exposure of some internal modes of the system which are bound states solutions of the first order Lamé equation. These modes generally characterize various fundamental background excitations that co-propagate with the optical periodic signals in the fiber. Direct numerical simulations of the DNLS amplitude equation depict the exponential decrease in the amplitude and corresponding increase in the width of the wave trains during propagation. Power lasers are used in order to compensate for fiber losses; this is realized via time-division multiplexing of optical pulses which are periodically pumped into the lossy fiber at regular distances within the framework of a distributed amplification scheme. This leads to the regular energy restoration in the lossy fiber as a result of the interactions between the energized multiplexed light signals (generated by the power lasers) and the propagating damped optical pulses, hence ensuring effective transmission over long distances.
The life
Authors: Bonds Mark Evan
Published: May 2022

‘The life’ presents an outline of the composer’s life from his early years in Bonn to his move to Vienna in 1792 to his death there in 1827. We know more about Beethoven than any composer who lived before him, and for that matter a great many who have come since. The sheer quantity of the historical record can seem overwhelming at times. The correspondence—more than 2,000 letters to and from him—extends across six hefty, printed volumes. The document now known as the Heiligenstadt Testament, written in 1802 but secreted away and not discovered until after his death, is a deeply personal and emotionally direct confrontation with the growing reality that he was losing his sense of hearing. In his later years, when his deafness had become severe, visitors often communicated by a combination of shouting and writing, and the 139 conversation books that have survived give us detailed insights into his daily concerns, with entries that range from the mundane to the metaphysical. The diary he kept sporadically between 1812 and 1818 records both philosophical and practical observations. Reminiscences of those who knew him personally fill two substantial volumes. And we have some 8,000 pages of musical sketches that range from brief melodic fragments to extensively drafted complete movements. These sketches allow us to trace the step-by-step growth of many of Beethoven’s landmark compositions, along with countless others he abandoned.
Love
Authors: Bonds Mark Evan
Published: May 2022

‘Love’ notes that Beethoven was “frequent in love, but usually only for a very short time,” according to his pupil Ferdinand Ries. The most intense of his many relationships was with a woman whose identity to this day remains disputed, known only as the “Immortal Beloved,” the composer’s appellation to her in a passionate letter of 1812. Antonie Brentano and Josephine von Brunsvick-Deym-Stackelberg are the two most plausible candidates. The letter was discovered in a secret compartment of Beethoven’s desk after his death. How and to what extent this affair affected Beethoven’s composition remains altogether unclear: the work most often associated with the Immortal Beloved—the song cycle An die ferne Geliebte, op. 98—has recently been shown to have been written as a commissioned memorial to the late wife of Prince Lobkowitz, one of the composer’s most important patrons in Vienna.
Composing
Authors: Bonds Mark Evan
Published: May 2022

‘Composing’ argues that the act of artistic creation of any kind is a process shrouded in mystery, and perhaps nowhere more so than in the realm of purely instrumental music, the kind on which Beethoven’s reputation has always rested. We nevertheless have a good sense of how Beethoven went about composing, thanks to the many sketchbooks he left behind. They document in fascinating detail the progression of a brief idea, sometimes little more than a simple interval, into a full-fledged theme which in turn undergoes multiple transformations of its own. The principal large-scale forms in which Beethoven and his contemporaries worked include sonata form, variation, and rondo. The fantasia, which follows no conventional outline, reflects Beethoven’s storied ability to improvise on the spot.
Evangelicalism: A Very Short Introduction
Authors: Stackhouse Jr. John G.
Published: May 2022

Evangelicalism: A Very Short Introduction examines the heart of the evangelical phenomenon. Evangelicalism encompasses many Protestant denominations that share core tenets of Christianity. It is foremost defined by its fervent worship, its regard for the Bible as the ultimate theological and ethical authority, the desire to evangelize, and the insistence on religious conversion known as being “born again.” As the Evangelical movement has grown rapidly, so has its influence on the political stage. This VSI tells the evangelical story from the preacher-led revivals of the eighteenth century, through the frontier camp meetings of the nineteenth, to the mass urban rallies of the twentieth and the global megachurches of the twenty-first.
Theodor W. Adorno: A Very Short Introduction
Authors: Bowie Andrew
Published: May 2022

Adorno: A Very Short Introduction studies the life and work of German philosopher and cultural theorist Theodor Adorno. It explains his most important ideas, and the historical, cultural, and political context of his writings. Adorno sought to understand the pathologies of modern societies epitomised by the Holocaust through critical engagement with fundamental ideas in philosophy, and social and cultural theory. He explored how human rationality can have irrational consequences, leading him to offer radical alternatives to ways of thinking about key issues in Western philosophy, such as ‘nature’, ‘history’, and ‘freedom’. The book also examines Adorno's critical assessments of how modern capitalism affects music and the other arts.