bluuebunny/crossref_metadata_2025 huggingface dataset:
On the relationship between electrical and electro-optical characteristics in vertical cavity surface emitting lasers for chip scale Rb atomic clocks
Authors: Mikhelashvili V. , Gal L. , Marciano I. R. , Willinger A. , Sery G. , Milyutin Y. , Ternyak O. , Shacham A. , Cohen A. , Orenstein M. , Eisenstein G.
Published: October 2024

We report on a comprehensive study of the electrical and electro-optical properties of 795 nm vertical cavity surface emitting lasers (VCSELs) designed for chip scale Rb atomic clocks. We highlight several key findings including the observation that the current flow at moderate bias levels comprises several parallel paths which are identified by an analysis of the I−V characteristic also confirmed by a numerical simulation. Resistance is a key parameter in any VCSEL. We analyze it in detail at all bias levels and find that above transparency, when the VCSEL enters the high injection regime, the current flow mechanism is modified significantly from an exponential to a power law characteristic. Consequently, resistance attains a nonlinear contribution which is quadratic in the spontaneous emission regime and quasi-linear above the threshold. This nonlinear contribution is not considered in common models. The optoelectronic properties are strongly correlated with the electrical characteristics what allow to explain several peculiarities of the VCSEL performance. We designed and fabricated the VCSELs according to the requirements of miniature Rb atomic clocks, including optimal operation at high temperatures. Their minimum threshold occurs at 363 K where they emit at 794.7 nm. The modal and polarization discrimination in the bias range where these VCSELs operate in practical miniature atomic clocks is well above 30 dB.
Mixing enhancement assisted by dual plate cavity in supersonic flow
Authors: Zhang Dongdong , Xie Haiwei , Xu Zheng , Tan Jianguo
Published: October 2024

Fast and efficient mixing of high-speed shear flow formed by fuel and oxidizer is of great importance for the improvement of rocket-based combined cycle engine performance. Nevertheless, the existence of compressibility effects of high-speed flow significantly inhibits the growth process of a mixing layer. Moreover, a finite-length combustor of the engine calls for more effective enhanced-mixing strategies to complete mixing in a shorter streamwise distance. To this end, in present paper, the strategy called dual plate cavity (DPC) is proposed to promote mixing. Three cases including the benchmark, front-DPC and back-DPC cases are selected to perform the comparative study. By means of high-order direct numerical simulations, the structure evolution characteristics and turbulence intensity distributions are researched. The index of velocity thickness is utilized to assess the mixing layer growth. The results indicate that with the introduction of DPC, the mixing process is dramatically promoted. The penetration behavior of newly found T-shaped structures into the upper main stream can engulf more fluid into the mixing region. Specifically, in the back-DPC case, the coexistence of both large-scale and small-scale structures in the far flow field can improve the turbulence intensity. The spatial correlation analysis results show that with the influence of DPC, the structure sizes are much larger than that of the benchmark case in the same streamwise position. Meanwhile, the contour line equal to 0.5 possesses property of distortion for the back-DPC case. The drastic pulsation of a mixing layer edge can obviously promote the mixing process. Through exploration of the enhanced-mixing mechanisms, this work indicates that the proposed DPC strategy is a good candidate for efficient mixing, and in the future, more detailed work including three-dimensional simulations concerning the strategy optimization is suggested to be performed.
Dynamic annealing assisted near-surface structural and bond stabilization in high-temperature low-energy N2+ implanted diamond
Authors: Fischer Miriam , Maity Sayantan , Kuntumalla Mohan Kumar , Hoffman Alon
Published: October 2024

Nitrogen-rich ultra-thin (1–2 nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800 eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C–N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500–600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800 eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented.
A comprehensive review on the fundamental principles, innovative designs, and multidisciplinary applications of micromixers
Authors: Han Wenbo , Li Wei , Zhang Hongpeng
Published: October 2024

This paper comprehensively reviews the fundamental principles, innovative designs, and multidisciplinary applications of micromixers. First, it introduces the fundamental principles of fluid mixing in micromixers, including passive and active mixing mechanisms, and the flow characteristics of fluids at the microscale. Subsequently, it focuses on the innovative design of passive micromixers, covering a variety of designs, such as obstacle structures, curved serpentine structures, groove structures, separation and recombination structures, topology optimization structures, and baffle structures, and analyzes the effects of different structures on mixing efficiency and pressure drop. In addition, it also studies the innovative design of active micromixers, including magnetic field assistance, electric field assistance, surface acoustic wave assistance, and thermal effect assistance, and analyzes the effects of different driving modes on mixing efficiency. Finally, it outlines the multidisciplinary applications of micromixers in the fields of biomedicine, chemical analysis, environmental monitoring and control, and new energy. This review aims to provide a comprehensive reference for the research and application of micromixers and promote their application in more fields.
Alteration in certain growth, biochemical, and anatomical indices of grapevine (Vitis vinifera) in response to the foliar application of auxin under water deficit
Authors: Khandani Yaser , Sarikhani Hassan , Gholami Mansour , Chehregani Rad Abdolkarim , Shirani Bidabadi Siamak
Published: October 2024

Drought-induced stress represents one of the most economically detrimental natural phenomena impacting grapevine (Vitis vinifera) development, yield, and fruit characteristics. Also, auxin is one of the most important plant growth regulators that can reduce damage caused by stress in plants. In this study, the impact of exogenously sprayed auxin (0, 50, and 200 mg L−1) on growth, biochemical, and anatomical parameters was investigated in two grapevine varieties (cvs. ‘Rashe’ and ‘Fakhri’) under water deficit. According to our findings, water deficit led to a notable decrease in growth, protein content, and anatomical parameters; but significantly enhanced electrolyte leakage. Grapevines exposed to water deficit exhibited substantial increases in total phenolic compounds and antioxidant activity. Applying 50 mg L−1 napthalene acetic acid (NAA) reduced the effects of water deficit in both grapevine cultivars by decreasing electrolyte leakage (15% in ‘Rashe’ and 20% in ‘Fakhri’), and accumulating protein content (22% ‘Rashe’ and 32% ‘Fakhri’), total phenolic compounds (33% ‘Rashe’ and 40% ‘Fakhri’), and antioxidant capacity (11% ‘Rashe’ and 39% ‘Fakhri’); anantomical parameters were also improved. However, application of 200 mg L−1 NAA had adverse effects on growth and biochemical traits of grapevines, with a more pronounced impact on root growth and anatomical parameters compared to other NAA concentrations. In conclusion, the application of 50 mg L−1 NAA enhanced grapevine growth, enabling them to better thrive under water deficit.
Non-compliance and under-performance in Australian human-induced regeneration projects
Authors: Macintosh Andrew , Evans Megan C. , Butler Don , Larraondo Pablo , Edirisinghe Chamith , Hunter Kristen B. , Evans Maldwyn J. , Ansell Dean , Waschka Marie , Lindenmayer David
Published: October 2024

The ‘boom-and-bust’ nature of rangelands makes them ill-suited to nature-based solutions (NbS) involving carbon sequestration in vegetation and soils. The variability in these ecosystems makes it difficult to determine whether carbon stock changes are attributable to project activities, creating additionality risks. Low and variable rainfall also means carbon stock increases will often be impermanent, being susceptible to reversals in droughts, a risk magnified by climate change. The small potential for gains per unit area over vast regions makes it difficult to accurately measure carbon stock changes at low cost. This creates pressure to trade accuracy for simplicity in measurement approaches, increasing the risk of errors. Despite these risks, rangelands have been advanced as suitable for offset projects because of low opportunity cost and a perception they are extensively degraded. The most prominent example globally is human-induced regeneration (HIR) projects under the Australian carbon credit unit (ACCU) scheme, which are purporting to regenerate permanent even-aged native forests (≥20% canopy cover from trees ≥2 metres high) across millions of hectares of largely uncleared rangelands, predominantly by reducing grazing pressure. Previous research found limited forest regeneration in the credited areas of these projects, and that most of the observed changes in tree cover were attributable to factors other than the project activities. Here we extend this research by evaluating compliance of a sample of 116 HIR projects with regulatory requirements and their performance in increasing sequestration in regeneration. The results suggest most HIR projects are non-compliant with key regulatory requirements that are essential to project integrity, and have had minimal impact on woody vegetation cover in credited areas. The findings point to major administrative and governance failings in Australia’s carbon credit scheme, and a significant missed opportunity to restore biodiversity-rich woodlands and forests in previously cleared lands via legitimate carbon offset projects.
Postcolonial images, ambivalence and weak border zones
Authors: Gallegos Krause Eduardo
Published: October 2024

This chapter deals with the largely unknown and slightly studied travel account of Otto Nordenskjöld in the
Argentinian-Chilean Patagonia as part of the preparation to his well-known and documented travel to Antarctica. By using
several key terms of postcolonial theory, such as ambivalence, border, identity, binaries and in-between, an analysis of the
way in which Nordenskjöld’s portrays the image of the Indigenous people and how civilisation treats them (from Nordenskjöld’s
perspective) is proposed. Thus, it is argued that, in the complex relation between travel account and images, an ambiguous
representation of European values and the Indigenous people arises, which destabilises the typical binaries of the colonial
discourse. The contribution demonstrates that, as travellers transition between two realms, they may find it challenging to
shed their European viewpoint, even in situations where colonial brutality is openly denounced.
Complements and adjuncts of one
in L2 English noun drop
Authors: Bruhn de Garavito Joyce
Published: October 2024

This study examines the constraint against complements of the pro-form one in L2
English of Spanish native speakers. Complements (*The belief in Santa is greater than the one in
Elvis) are disallowed, in contrast to adjuncts (The vase in the bedroom is nicer than the one in
the kitchen). Spanish exhibits opposite tendencies in noun ellipsis: complements are productive but
adjuncts are often restricted. Advanced Spanish learners performed as well as native speakers for most relevant
properties but there was a tendency to accept complements to a greater extent than the English L1 speakers. However,
7/15 participants performed in a native-like manner, evidence that learners are capable of overcoming L1 effects in
spite of the relative infrequency of relevant contexts.
Second language acquisition of English plurals by Chinese learners
Authors: Liu Yi , Gil Kook-Hee
Published: October 2024

Previous research supported the proposal that multiplicity inferences (i.e., the more than
one interpretation) associated with English plural morphology are scalar implicatures (Tieu et al., 2014). The current study extends the research to second language
(L2) acquisition by testing Chinese-speaking learners of English. Using a Truth Value Judgment Task (TVJT) adapted
from Tieu et al. (2014), we compared the interpretations of English bare
plurals among Chinese adult learners and native English speakers. Results indicate that the interpretive pattern of
Chinese learners closely aligns with that of the English controls’. This supports the universality of scalar
implicatures in L2 and does not provide direct evidence for L1 transfer through morpheme mapping from English plural
morpheme -s to Chinese plural morpheme -men.
L2 acquisition of English flexible count and flexible mass nouns by L1-Japanese and L1-Spanish
speakers
Authors: Snape Neal , Umeda Mari , Hosoi Hironobu
Published: October 2024

We examine the acquisition of the English count-mass distinction, in particular
flexible nouns. Certain nouns are flexible in English as they can be either countable like
a cake / cakes or mass such as cake. Our study is unique
regarding the off-line and on-line tasks used and the L2 participant groups. We administered a quantity judgement task
and a self-paced reading task to L1-Japanese and L1-Spanish speakers who judged four conditions – Count, Object,
Substance and Flexible. The findings show that both L1-Japanese and L1-Spanish speakers performed differently on both
tasks from the native speaker controls. We argue that the results of the self-paced reading task are inconsistent with
the claims made by the Morphological Congruency Hypothesis (Jiang et al.,
2011).
Sensitivity to silently structured interveners
Authors: Miura Atsushi
Published: October 2024

One of the central issues in generative approaches to second language acquisition is whether second
language (L2) learners can use syntactic manipulation in the L2, as they do in the first language (L1). To explore
this issue, this study investigates sensitivity to intervention effects in sluicing structures, specifically, the
asymmetry between object and subject extraction. The results of a picture-sentence judgment task indicate that
L1-Japanese/L2-English learners with relatively low proficiency exhibit sensitivity to the intervention effect,
showing greater difficulty in the case of object extraction in both non-sluicing and sluicing structures.
Consequently, this study suggests that even learners with low L2 proficiency can achieve deep syntactic manipulations,
including building up an elided structure and moving the wh-element from it.
“And yet it moves”
Authors: Archibald John
Published: October 2024

The study of Lx phonology is under-represented in the GenSLA literature. I argue that this is
largely because the complex learnability issues in the phonological domain have been under-appreciated. Drawing on
examples from features and syllables, I illustrate that the acquisition of phonology is subject to poverty of the
stimulus effects. Consequently, it follows that phonological representations are learned and not merely noticed in the
environment. Furthermore, phonological grammars are shown to be generative, and hierarchical. By adopting abstract
representational models we can both describe and explain learner behaviour. I explore the role of phonology in
morphological and syntactic interfaces, and conclude with a discussion of real-world implications with regard to
pronunciation training, and broader societal concerns.
CCQM-K173.1 - Assay of sodium carbonate. Final report
Authors: Máriássy Michal , Hankova Zuzana , Jo Kyungmin
Published: October 2024

Main text

The CCQM key comparison CCQM-K173.1 is a subsequent comparison to CCQM-K173. It was performed to demonstrate the capability of KRISS to measure the amount content of bases. The institutes could use a method of their choice, although the use of coulometry or titrimetry with potentiometric determination of the endpoint was expected. The result of SMU was used as a link to the original comparison CCQM-K173.

The results of KRISS were in good agreement with the reference value and may serve as evidence to support respective CMC claims.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
An experiment to measure electromagnetic memory
Authors: Bieri Lydia , Garfinkle David
Published: October 2024

We describe an experiment to measure the electromagnetic analog of gravitational wave memory, the so-called electromagnetic (EM) memory. Whereas gravitational wave memory is a residual displacement of test masses, EM memory is a residual velocity (i.e. kick) of test charges. The source of gravitational wave memory is energy that is not confined to any bounded spatial region: in the case of binary black hole mergers the emitted energy of gravitational radiation as well as the recoil energy of the final black hole. Similarly, EM memory requires a source whose charges are not confined to any bounded spatial region. While particle beams can provide unbounded charges, their currents are too small to be practical for such an experiment. Instead we propose a short microwave pulse applied to the center of a long dipole antenna. In this way the measurement of the kick can be done quickly enough that the finite size of the antenna does not come into play and it acts for our purposes the same as if it were an infinite antenna.
Polarization-selective dual-band infrared metamaterial perfect absorber
Authors: Chang Fangjin , Wang Qiao , Kuang Kaili , Peng Wei
Published: October 2024

Metamaterial absorbers have significant effects and great potential for applications in a variety of important sciences and technologies, including infrared imaging, thermal emitters, electromagnetic shielding, and photodetectors. However, conventional absorbers with a single function are difficult to meet the growing demand of devices, especially for the situations where the absorption and polarization are simultaneously required in infrared detection. If the polarization absorption function is realized by integrating absorption and polarization elements, it will lead to a large overall system size and slow response time. To solve this problem, we propose a dual-band polarization-selective metamaterial perfect absorber, whose maximum absorptions at resonant wavelengths of

λ
1

=
2.824

μ

m

and

λ
2

=
7.622

μ

m

are 99.99% and 99.88%, respectively. The absorber exhibits strong polarization sensitivity, absorbing TM-polarized incident light and reflecting TE-polarized incident light at the two resonant wavelengths. The extinction ratios of the absorber at the two referred resonant wavelengths are 90.9 and 142.7, respectively. The proposed absorber would be beneficial for infrared polarization detection and imaging.
Mechanisms and models of interface trap annealing in positively-biased MOS devices
Authors: Song Yu , Qiu Chen , Zhou Hang , Liu Yang , Chen Xiang , Wei Su-Huai
Published: October 2024

We propose a hydrogen anion (H−) passivation mechanism for the interface trap annealing (ITA) in positively-biased metal–oxide–semiconductor (MOS) devices. It is demonstrated that, the protons (H+) released in SiO2 due to H2 cracking on oxide traps can migrate into Si at relatively high temperature (HT), therefore passivating the interfacial Pb
centers by capturing two electrons provided by the positive bias. This new mechanism explains the elimination temperature of about 100 ∘C in experiments, which is much lower than temperature above 220 ∘C predicted by the traditional H2 passivation mechanism. We also derive analytic models of the ITA, based on the coupling transformation dynamics between oxide and interface traps, as well as the concept of hierarchically constrained dynamics in glassy materials. These models can universally describe a generation-to-elimination transition of Pb
, and predict the enhanced elimination of

E
γ

′

as observed when the annealing temperature is elevated. Moreover, we demonstrate that, the defect annealing models can be applied to analysis the nonmonotonic temperature dependence of the annealing of threshold voltage shift in nMOS devices. Our findings provide a theoretical basis for achieving the low temperature elimination of interface traps, and for setting the HT stages of accelerated aging and damage evaluations of MOS devices.
RABV antigenic peptide loaded polymeric nanoparticle production, characterization, and preliminary investigation of its biological activity
Authors: Bezir Kübra , Pelit Arayici Pelin , Akgül Buşra , Abamor Emrah Şefik , Acar Serap
Published: October 2024

Nanoparticle-based antigen carrier systems have become a significant area of research with the advancement of nanotechnology. Biodegradable polymers have emerged as particularly promising carrier vehicles due to their ability to address the limitations of existing vaccine systems. In this study, we successfully encapsulated the G5-24 linear peptide, located between amino acids 253 and 275 in the primary sequence of the rabies virus G protein, into biodegradable and biocompatible PLGA copolymer using the double emulsion solvent evaporation method. The resulting nanoparticles had a size of approximately 230.9 ± 0.9074 nm, with a PDI value of 0.168 ± 0.017 and a zeta potential value of −9.86 ± 0.132 mV. SEM images confirmed that the synthesized nanoparticles were uniform in size and distribution. Additionally, FTIR spectra indicated successful peptide loading into the nanoparticles. The encapsulation efficiency of the peptide-loaded nanoparticles was 73.3%, with a peptide loading capacity of 48.2% and a reaction yield of 30.4%. Peptide release studies demonstrated that 65.55% of the peptide was released in a controlled manner over 28 d, following a ‘biphasic burst release’ profile consistent with the degradation profile of PLGA. This controlled release is particularly beneficial for vaccine studies. Cytotoxicity tests revealed that the R-NP formulation did not induce cytotoxicity in fibroblast cells and enhanced NO production in macrophages, indicating its potential for vaccine development.
Ultra-high PDCR(>109) of vacuum-UV photodetector based on Al-doped Ga2O3 microbelts
Authors: Hu Zhi-Pin , Chen Hai-Feng , Ding Zi-Jie , Lu Qin , Li Li-Jun , Liu Xiang-Tai , Wang Shao-Qing , Wang Zhan , Jia Yi-Fan
Published: October 2024

Al-doped Ga2O3 microbelts with widths ranging from 20 to 154 μm and lengths up to 2 mm were grown using carbothermal reduction. Based on these ultra-wide microbelts, single-microbelt (37 μm wide) and double-microbelts(38 μm/42 μm wide) metal-semiconductor-metal photoconductive ultraviolet (UV) detectors PDs were fabricated and their optoelectronic performances were investigated at Vacuum-UV (VUV) wavelengths of 185 nm. Under irradiation of 185 nm, the Al-doped Ga2O3 PD has a very-high photocurrent (I
ph) of 192.07 μA and extremely low dark current (I
d) of 156 fA at 10 V, and presents a ultra-high light-to-dark current ratio of 1.23 × 109. The responsivity (R), external quantum efficiency (EQE), and detectivity (D*) of the double-microbelts detector device were 1920 A W−1, 9.36 × 105%, and 8.6 × 1016 Jones, respectively. Since the bandgap of the Al-doped microbelts becomes wider, and the fabricated detector has weaker sensitivity to radiation in the 254/365 nm wavelengths. Compared with the 254 nm and 365 nm UV cases, the devices under 185 nm VUV show the excellent high selectivity ratios of 1.47 × 106 and 1.7× 107, respectively. This paper should provide a new insight on the VUV photodetectors utilizing Ga2O3 microbelts.
Real-time measurement of two-dimensional LET distributions of proton beams using scintillators
Authors: Isomura Taiki , Kamizawa Satoshi , Takada Kenta , Mori Yutaro , Sakae Takeji
Published: October 2024

Objective. The linear energy transfer (LET) of proton therapy beams increases rapidly from the Bragg peak to the end of the beam. Although the LET can be determined using analytical or computational methods, a technique for efficiently measuring its spatial distribution has not yet been established. Thus, the purpose of this study is to develop a technique to measure the two-dimensional LET distribution in proton therapy in real time using a combination of multiple scintillators with different quenching. Approach. Inorganic and organic scintillator sheets were layered and irradiated with proton beams. Two-color signals of the CMOS sensor were obtained from the scintillation light and calibration curves were generated using LET. LET was calculated using Monte Carlo simulations as

LE

T

t

and

LE

T

d

weighted by fluence and dose, respectively. The accuracy of the calibration curve was evaluated by comparing the calculated and measured LET values for the 200 MeV monoenergetic and spread-out Bragg peak (SOBP) beams. LET distributions were obtained from the calibration curves. Main results. The deviation between the calculated and measured LET values was evaluated. For both

LE

T

t

and

LE

T

d

, the deviation in the plateau region of the monoenergetic and SOBP beams tended to be larger than those in the peak region. The deviation was smaller for

LE

T

d

. In the obtained

LE

T

d

distribution, the deviation between the calculated and measured values agreed within 3% in the peak region, while the deviation was larger in other regions. Significance. The LET distribution can be measured with a single irradiation using two scintillator sheets. This method may be effective for verifying LET in daily clinical practice and for quality control.
Principles and prospects of Bose-Einstein correlation study at BESIII*
Authors: Hu 胡 Hai-Ming 海明 , Huang 黄 Guang-Shun 光顺
Published: October 2024

One method for determining the characteristic parameters of a hadron production source is to measure the Bose-Einstein correlation functions. In this study, we present fundamental concepts and formulas related to the Bose-Einstein correlations, focusing on the measurement principles and the Lund model from an experimental perspective. We perform Monte Carlo simulations using the Lund model generator in the 2–3 GeV energy range. Through these feasibility studies, we identify key features of the Bose-Einstein correlations that offer valuable insights for experimental measurements. Utilizing data samples collected at BESIII, we perform measurements of the Bose-Einstein correlation functions, with an expected experimental precision of a few percent for the hadron source radius and incoherence parameter.
Optimized BP-LSTM neural network based on IGA for heat exchanger outlet temperature prediction
Authors: Zhang Yu , Xu Bing
Published: October 2024

In this paper, an improved Genetic Algorithm (IGA) is proposed to optimize the BP-LSTM neural network for predicting heat exchanger temperature. The study introduces an enhanced genetic algorithm designed to optimize both short- and long-term memory networks (LSTM) in conjunction with the BP neural network temperature prediction model and the BP-LSTM neural network model. Simulation and comparison results demonstrate that the proposed prediction method can effectively forecast heat exchanger temperatures.
Application of improved deep learning algorithm in obstacle avoidance of UAV
Authors: Lu Qi , Guo Lejiang , Sun Xu
Published: October 2024

To enhance the intelligent obstacle avoidance capabilities of unmanned aerial vehicles (UAVs), we introduce a refined version of the You Only Look Once (YOLO) algorithm, termed Improved YOLO (I-YOLO). This novel algorithm not only maintains the swift detection speed inherent in the original YOLO but also augments its feature enhancement network. Specifically, we propose a three-branch parallel feature pyramid network (TBPFP) to capture richer semantic information pertaining to the context of small obstacles. Furthermore, we incorporate a generative adversarial network (GAN) in a cascaded manner to synthesize more realistic super-resolution images, thereby bolstering detection accuracy. Experimental evaluations demonstrate that, in comparison to the baseline YOLO algorithm, our I-YOLO variant exhibits superior detection precision and feature extraction capabilities in the perception of intricate environmental targets. While there is a modest decrement in detection speed, it remains adequate to fulfill real-time requirements, particularly in the context of video stream processing.
Metagenomic analysis of sedimentary archives reveals ‘historical’ antibiotic resistance genes diversity increased over recent decades in the environment
Authors: Yan Dongna , Han Yongming , Liu Jinzhao , Zan Sifan , Lu Yanfeng , An Zhisheng , Capo Eric
Published: October 2024

Antibiotic Resistance Genes (ARGs) are widespread in freshwater environments and represent a concealed threat to public health and aquatic eco-system safety. To date, only a limited number of studies have investigated the historical distribution of ARGs and their hosts through the analysis of freshwater sedimentary archives. This research gap constrains our comprehensive of the mechanisms underlying natural bacterial resistance formation during pre-antibiotic era (prior to the 1940s) and the development of human-induced bacterial resistance in post-antibiotic era (since the 1940s). In this study, we examined the vertical distribution patterns of ARGs and their associated hosts within a sedimentary core from a eutrophic lake, employing shotgun sequencing methodology. The findings revealed a marked increase in ARG diversity during post-antibiotic era, and the predominant ARG types identified included those conferring resistance to multidrug, bacitracin, macrolide–lincosamide–streptogramin, beta-lactam, tetracycline, fluoroquinolone, glycopeptide and aminoglycoside, collectively accounting for 78.3%–85.6% of total ARG abundance. A total of 127 ARG subtypes were identified in samples, and 48 ARG subtypes shared across vertical sediment resistome profile with two of them, bacA and bcrA, occurring only in post-antibiotic era. Further, 137 metagenome-assembled genomes (83 species belonging to 12 phyla) were identified as ARG hosts, mainly belonging to the phyla Proteobacteria, Nitrospirota, Chloroflexota, Bacteroidota, Actinobacteriota, Cyanobacteria, and Firmicutes. Significant correlation was found between the diversity of ARG and the concentrations of organic matter and heavy metals, suggesting a common source of contamination. Aside the fact that human-induced eutrophication is a forcing factor acting in parallel to increase ARGs releases in water systems, both being indicators of increased urbanization in the catchment, eutrophication may significantly increase bacterial activity, thereby facilitating the spread of antibiotic-resistant bacteria in environment. This study reveals the marked increased in ARG diversity with the onset of antibiotic use by human societies with potential impact of aquatic ecosystem.
The level of preparedness of the local community for sustainable community tourism development in Mai Hich commune, Mai Chau district, Hoa Binh province, Vietnam
Authors: Thao N P , Trang D H , Huong P L , Tien N V , Thao P T
Published: October 2024

This study aims to assess the community’s readiness for implementing sustainable community tourism development in Mai Hich commune, Mai Chau district, Hoa Binh province. Evaluating the community’s readiness for sustainable tourism development is crucial to mitigate potential negative impacts from tourism activities. The research utilizes a mixed-methods approach, combining qualitative and quantitative research to determine the local community’s level of readiness for sustainable tourism development. The community’s readiness is found to be high in social and cultural aspects, while economic aspects reveal certain challenges. Additionally, the study analyzes various forms of community service provision. Survey results indicate that the local community’s involvement in tourism activities is rather limited, sporadic, and primarily characterized by small-scale, self-initiated endeavors. There is a lack of investment in products and services catering to tourists. These findings pose challenges for the development of sustainable community tourism in Mai Hich commune, Mai Chau district, Hoa Binh province.
Dual-mode 1 × 2 optical switch with simultaneous modulation based on inverse design devices
Authors: Wang Junqing , Jia Hao , Yang Shanglin
Published: October 2024

Mode division multiplexing (MDM) technology, based on the parallelism inherent in mode dimensions, provides an advancement in enhancing on-chip optical communication channel capacity. In MDM communication systems, the routing and switching of optical signals are of essential importance. However, conventional multimode optical switches typically follow the demultiplexing-processing-multiplexing technological route, leading to an unavoidable increase in device size. In scenarios where multiple modes need to be routed synchronously, the implementation of simultaneous modulation optical switches offers a more efficient and feasible solution. Here, we propose two 1 × 2 dual-mode optical switches with simultaneous modulation on a silicon-on-insulator platform in the 1525–1565 nm wavelength range, utilizing two optical phase modulation techniques: mode transformation and waveguide widening. Simultaneously, we employ inverse design methodologies based on the adjoint variable method and level-set method to create the compact single-connected devices, which are compatible with complementary metal-oxide semiconductor fabrication processes. The experimental results show that the insertion losses for both TE0 and TE1 modes are less than 1.6 dB (2.5 dB), with the worst modal crosstalk at most −13.5 dB (−12.7 dB) for the switch based on mode transformation (waveguide widening) strategy at the wavelength of 1550 nm. The extinction ratio of the two proposed optical switches exceeds 25 dB at the same wavelength. Furthermore, the switches exhibit a 10%–90% rise time of 15.2 μs and a 90%–10% fall time of 19.5 μs at 1550 nm, indicating the switching speed can be up to kilohertz. Our proposed 1 × 2 optical switches hold potential as a fundamental unit for optical signal switching in high-integration multimode optical communication systems.
Multi task deep learning phase unwrapping method based on semantic segmentation
Authors: Wang Linlin , Liang Wenjie , Guo Wanyi , Wang Zhujun , Wang Chuanyun , Gao Qian
Published: October 2024

Phase unwrapping is a key step to obtain continuous phase distribution in optical phase measurement. When the wrapped phase obtained from the interference pattern is unclear and noisy, estimating the unwrapped phase becomes more challenging. As deep learning advances in optical image processing, it will enhance processing efficiency and accuracy, bringing broader possibilities for various applications. This paper introduces an innovative phase unwrapping method based on multi-task learning, aiming to simultaneously enhancing denoised images and predicting wrap count. The proposed network, named ICER-Net, comprises an encoder and two decoders, transforming the input low-luminance, noisy wrapped phase into two intermediate outputs: enhanced wrapped phase and wrap count. Finally, these two intermediate results are fused to obtain the unwrapped phase. Experimental results demonstrate that ICER-Net not only enhances the accuracy of phase unwrapping, particularly when facing challenges of various noise levels and luminance sizes but also exhibits outstanding performance in actual collected speckle phase images. This indicates that ICER-Net holds significant superiority in addressing complex issues in optical image processing.
Gate voltage dependence on the density of state of 30° twisted bilayer graphene using Trotter–Suzuki tight-binding time propagation method
Authors: Susanto Jaysen Brian , Widianto Eri , Subama Emmistasega , Nurwantoro Pekik , Santoso Iman
Published: October 2024

Twisted multilayer structures are considered a helpful framework for exploring strongly correlated many-particle systems, where phenomena of physics correlation emerge. Here, we present the Trotter–Suzuki tight-binding time propagation method for computing the density of states (DOS) in a 30° twisted bilayer graphene (TBG). This method solves the time-dependent Schrödinger equation by decomposing Hamiltonian matrices to derive the correlation function. The Fourier transform of this correlation function yields the DOS of the system up to ≈ 1000 000 atoms. Our calculation proves that geometry makes an outstanding contribution to our final results. Additionally, applying additional gate voltage induces shifts in Van Hove singularities, potentially leading to the emergence of new states at the Fermi energy level. The results demonstrate that TBG systems can be easily adjusted and modified for further investigation of optoelectronic features.
Systematic review of experimental paradigms and deep neural networks for electroencephalography-based cognitive workload detection
Authors: K N Vishnu , Gupta Cota Navin
Published: October 2024

This article summarizes a systematic literature review of deep neural network-based cognitive workload (CWL) estimation from electroencephalographic (EEG) signals. The focus of this article can be delineated into two main elements: first is the identification of experimental paradigms prevalently employed for CWL induction, and second, is an inquiry about the data structure and input formulations commonly utilized in deep neural networks (DNN)—based CWL detection. The survey revealed several experimental paradigms that can reliably induce either graded levels of CWL or a desired cognitive state due to sustained induction of CWL. This article has characterized them with respect to the number of distinct CWL levels, cognitive states, experimental environment, and agents in focus. Further, this literature analysis found that DNNs can successfully detect distinct levels of CWL despite the inter-subject and inter-session variability typically observed in EEG signals. Several methodologies were found using EEG signals in its native representation of a two-dimensional matrix as input to the classification algorithm, bypassing traditional feature selection steps. More often than not, researchers used DNNs as black-box type models, and only a few studies employed interpretable or explainable DNNs for CWL detection. However, these algorithms were mostly post hoc data analysis and classification schemes, and only a few studies adopted real-time CWL estimation methodologies. Further, it has been suggested that using interpretable deep learning methodologies may shed light on EEG correlates of CWL, but this remains mostly an unexplored area. This systematic review suggests using networks sensitive to temporal dependencies and appropriate input formulations for each type of DNN architecture to achieve robust classification performance. An additional suggestion is to utilize transfer learning methods to achieve high generalizability across tasks (task-independent classifiers), while simple cross-subject data pooling may achieve the same for subject-independent classifiers.
A space-time mixed finite element method for reduced fracture flow models on nonmatching grids
Authors: Hoang Thi-Thao-Phuong , Yotov Ivan
Published: October 2024

This paper is concerned with the numerical solution of the flow problem in a fractured porous medium where the fracture is treated as a lower dimensional object embedded in the rock matrix. We consider a space-time mixed variational formulation of such a reduced fracture model with mixed finite element approximations in space and discontinuous Galerkin discretization in time. Different spatial and temporal grids are used in the subdomains and in the fracture to adapt to the heterogeneity of the problem. Analysis of the numerical scheme, including well-posedness of the discrete problem, stability and a priori error estimates, is presented. Using substructuring techniques, the coupled subdomain and fracture system is reduced to a space-time interface problem which is solved iteratively by GMRES. Each GMRES iteration involves solution of time-dependent problems in the subdomains using the method of lines with local spatial and temporal discretizations. The convergence of GMRES is proved by using the field-of-values analysis and the properties of the discrete space-time interface operator. Numerical experiments are carried out to illustrate the performance of the proposed iterative algorithm and the accuracy of the numerical solution.
Reducing polynomial degree by one for inner-stage operators affects neither stability type nor accuracy order of the Runge–Kutta discontinuous Galerkin method
Authors: Sun Zheng
Published: October 2024

The Runge–Kutta (RK) discontinuous Galerkin (DG) method is a mainstream numerical algorithm for solving hyperbolic equations. In this paper, we use the linear advection equation in one and two dimensions as a model problem to prove the following results: For an arbitrarily high-order RKDG scheme in Butcher form, as long as we use the

P
k

P^k

approximation in the final stage, even if we drop the

k
k

th-order polynomial modes and use the

P

k
−
1

P^{k-1}

approximation for the DG operators at all inner RK stages, the resulting numerical method still maintains the same type of stability and convergence rate as those of the original RKDG method. Numerical examples are provided to validate the analysis. The numerical method analyzed in this paper is a special case of the Class A RKDG method with stage-dependent polynomial spaces proposed by Chen, Sun, and Xing [arXiv preprint, arXiv:2402.15150, 2024]. Our analysis provides theoretical justifications for employing cost-effective and low-order spatial discretization at specific RK stages for developing more efficient DG schemes without affecting stability type and accuracy order of the original method.
Chromosome 8 inversion mutation in congenital generalized hypertrichosis: localization of precise breakpoints
Authors: Zhao Anqi , Cao Qiaoyu , Pan Chaolan , Wang Xiaoxiao , Wang Yumeng , Li Ming
Published: October 2024

We report a three-generation family with congenital generalized hypertrichosis (CGH), identifying an inversion variant on chromosome 8: inv(8)(q24.13q24.3) through comprehensive genetics analysis. Our report enriches the spectrum of CGH and its mutation profile.
Regulating composition and structure of coal-based graphene and its electrochemical characteristics
Authors: Liu Wenfeng , Li Jun , Zhang Yating , Li Keke , Liu Zhen , Guo Cliff Yi , Wang Jingjing , Wei Linlin
Published: October 2024

Coal, a carbon-rich mineral with plentiful reserves, serves not only as a fuel but also as a raw material, presenting lower pollution emissions in the latter use. From a materials chemistry standpoint, coal is a viable raw material for graphene production. This study develops a promising and sustainable method to convert coal into graphene, leveraging its unique macromolecular aromatic structure and high carbon content. The investigation includes an analysis of the lateral size, morphology, and chemical composition of coal-derived graphene using techniques such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and optical microscopy. Results confirm that coal can effectively replace natural graphite flakes in graphene production, with the derived graphene featuring three to six exfoliated layers and an oxygen content below 5.5%. While the graphene from coal shares a similar morphology to that derived from graphite, it exhibits more structural defects. Interestingly, the macroscopic size of the coal does not influence the microscopic composition and structure of the graphene. However, the thermal reduction method for oxidized graphene proves more effective at repairing structural defects than chemical reduction. Employing coal-derived graphene as a supercapacitor electrode demonstrates excellent cycling stability and ultra-high capacitance storage capacity. The H-CG-325 shows the highest discharge area-specific capacitance across various current densities. At an increased current density of 10 A/g, the H-CG-325 maintains 80.6% of its initial capacitance of 79 F/g observed at 1 A/g. Electrochemical tests reveal that coal-based graphene holds significant potential as a supercapacitor material, indicating promising applications in energy storage and conversion.
Advanced electrocardiography heart age: a prognostic, explainable machine learning approach applicable to sinus and non-sinus rhythms
Authors: Al-Falahi Zaidon S , Schlegel Todd T , Palencia-Lamela Israel , Li Annie , Schelbert Erik B , Niklasson Louise , Maanja Maren , Lindow Thomas , Ugander Martin
Published: October 2024

Aims

An explainable advanced electrocardiography (A-ECG) Heart Age gap is the difference between A-ECG Heart Age and chronological age. This gap is an estimate of accelerated cardiovascular aging expressed in years of healthy human aging, and can intuitively communicate cardiovascular risk to the general population. However, existing A-ECG Heart Age requires sinus rhythm. We aim to develop and prognostically validate a revised, explainable A-ECG Heart Age applicable to both sinus and non-sinus rhythms.

Methods and results

An A-ECG Heart Age excluding P-wave measures was derived from the 10-s 12-lead ECG in a derivation cohort using multivariable regression machine learning with Bayesian 5-min 12-lead A-ECG Heart Age as reference. The Heart Age was externally validated in a separate cohort of patients referred for cardiovascular magnetic resonance imaging by describing its association with heart failure hospitalization or death using Cox regression, and its association with comorbidities. In the derivation cohort (n = 2771), A-ECG Heart Age agreed with the 5-min Heart Age (R2 = 0.91, bias 0.0 ± 6.7 years), and increased with increasing comorbidity. In the validation cohort [n = 731, mean age 54 ± 15 years, 43% female, n = 139 events over 5.7 (4.8–6.7) years follow-up], increased A-ECG Heart Age gap (≥10 years) associated with events [hazard ratio, HR (95% confidence interval, CI) 2.04 (1.38–3.00), C-statistic 0.58 (0.54–0.62)], and the presence of hypertension, diabetes mellitus, hypercholesterolaemia, and heart failure (P ≤ 0.009 for all).

Conclusion

An explainable A-ECG Heart Age gap applicable to both sinus and non-sinus rhythm associates with cardiovascular risk, cardiovascular morbidity, and survival.