bluuebunny/crossref_metadata_2025 huggingface dataset:
Pragmatic Study of Botnet Attack Detection In An IoT Environment
Authors: Vennapureddy Rajasree , Srinivasulu T.
Published: November 2024

A comprehensive search for primary research published between 2014 and 2023 was carried across several databases. Studies that describe the application of machine learning (ML) and deep learning techniques for if they was carried out across several databases. Studies that described the application of deep learning (DL) and machine learning (ML) methods for IoT botnet attack detection. Numerous facets of contemporary life have been transformed by the Internet of Things (IoT), including home automation, industrial control systems, healthcare, and transportation. On the other hand, as more devices become connected, security risks have also increased, especially from botnets. IoT Botnet attack detection techniques utilizing ML and DL have been developed in order to reduce these dangers. The best DL and ML techniques for IoT botnet attack detection are identified by a detailed examination of evaluation criteria, and performance measures in this systematic review. Performance metrics from well-known machine learning models are used to illustrate how well these machine learning techniques detect and stop Botnet attacks. When it comes to detecting Botnet assaults, deep learning (DL) and traditional machine learning (ML) methods perform similarly well. Furthermore, traditional machine learning systems still have challenges with real-time monitoring, timely detection and adaptability to novel attack approaches.
Smart Living and Smart Environment Concepts as Elements to Create a Solo Smart City
Authors: Ardana Shildamullah Danendra Mukti , Nurmandi Achmad , Fridayani Helen Dian , Chiang Li-Chun
Published: November 2024

In the context of Smart City, there are several indicators to realize Smart City one of them is Smart Living and Smart Environment. Both indicators are important because they include parameters of good infrastructure availability, facilities, open public green spaces and waste management that is now a waste power plant (PLTSa) in Solo City. In connection with that, the Solo City Government continues to encourage development and development in order to prosper society. This research uses qualitative methods with descriptive types. Secondary data sources are obtained through mass media news, articles, journals, literature or previous studies with relevant themes or topics about Smart City that then analyze data by processing using VOSviewers and Nvivo software tools that serve as data visualization aimed to learn more in relation to the application of Smart Living and Smart Environment concepts to realize Solo Smart City. In this study, the results were obtained that the majority of the mass media talked about the City of Solo and one of the processing of its visualization data showed that facility construction as well as the availability of infrastructure in the city of Solo were quite dominant. It is supported by the entry of Solo City in the top tier of habitable cities according to the Most Livable City Index in 2022 beating four other major cities in Indonesia. The novelty in this research is to focus on a more in-depth discussion and supported by data and data visualization about the concept of smart living, whether living in a solo city is worth it, then how the city is and is combined with the smart environment concept.
The Contemporary Significance of Marxist Ecological Philosophy
Authors: Nguyen Phuoc Tai , Tran Mong Nghi
Published: November 2024

Marxist ecological philosophy carries profound implications and serves as the guiding principle for constructing an ecologically advanced society. The essence and fundamental principle of Marxist philosophy is to demand individuals to fully utilize their subjective agency and achieve the harmonization and integration of humanity and the natural world by adhering to objective rules. An extensive examination of Marxist ecological philosophy holds significant theoretical and practical significance in the pursuit of constructing a harmonious and sustainable planet.
Review of Forest Management in Indonesia Towards a Sustainable Environment
Authors: Solihah Sayidah Ummul , Nurmandi Achmad , Fridayani Helen Dian
Published: November 2024

This study aims to analyze the efforts made by Indonesia in managing the forest environment. The reason is that Indonesia is ranked 164th out of 180 countries regarding environmental performance by The Environmental Performance Index (EPI) with a score of 28.20 points which is categorized as a country with low forest management. This study uses a qualitative method with research data obtained by means of desk studies from secondary data through online mass media reports in the period 2020 – 2024 and previous studies both from photos, archives, documents, and reports. The results of the study show that the forest management process in Indonesia is more inclined to efforts to preserve nature. Although various methods have been carried out, obstacles are still found in the fragility of the forest resource asset security system, weak forest institutions in the field, and the control of licensing administration by the government are factors that worsen forest management in Indonesia. So that the efforts made by Indonesia in managing the forest environment have not been optimal and are very far from perfect.
Peer Counselor Communication Style In Increasing UMY Students’ Awareness Of Mental Health
Authors: Suciati  , Putri Devi Lianda , Ronayunita Audhi
Published: November 2024

Peer counselors’ communication style towards clients plays an important role in the success of increasing students’ mental awareness. Therefore, this research will discuss peer communication styles with clients as UMY’s efforts to promote awareness regarding mental health. This research aims to determine the communication style of peer counselors to clients at UMY in improving students’ mental well-being. This type of research is descriptive qualitative with data collection techniques of in-depth interviews with six of peer counselors and clients. The data analysis technique is carried out using interactive analysis, where interaction occurs between data collection, data presentation, and conclusion. In this research, it was found that six peer counselors had different communication styles to convey messages to each client, namely cartoon communication; open and leave a message; relaxed, friendly, and attentive. The application of this communication style is influenced by factors that arise from the start to the end of the counseling session. The communication style of peer counselors in higher education, especially UMY, has never been examined in previous research. So, it is hoped that the presence of this research can become a reference for creating a higher education environment that supports students’ overall mental well-being.
Difficulties of Non-English Study Program Students in Taking the TOEFL-Like Test at Universitas Muhammadiyah Yogyakarta: A Case Study of UMY Economics Study Program Students batch 2022
Authors: Setiawati Sri Ani Puji , Farahsani Yashinta , Febrindasari Chyndy
Published: November 2024

This study aims to examine TOEFL-like results and the challenges faced by non-English-speaking students attempting TOEFL-like questions. This examination utilized a subjective illustrative technique, with an example size of 30 understudies chosen through purposive inspecting from a more extensive populace of 100 understudies. Interviews and a TOEFL-like test are two methods of data collection. According to the data, participants found Structure and Written Expression to be the most challenging of the three sections of the TOEFL-like test, followed by Reading Comprehension and Listening Comprehension. It is possible to draw the conclusion that non-English study program students face the greatest difficulty on the TOEFL-like Structure and Written Expression section. The Design was appraised as more troublesome than the Composed Articulation part. The Reading Comprehension section is the second most challenging for students. The data indicate that the most challenging aspect of Reading Comprehension is the identification of difficult words; however, subjects, explanatory sentences, and references are deemed easier than the others. The Listening Comprehension section appears to be the most straightforward. They have trouble following conversations that are both long and short in length. Overall, this study reveals the specific challenges that non-English study program students face when answering TOEFL-like exam questions, highlighting areas in which they need additional support and attention to improve their language learning prospects.
Understanding CEFR Language Levels: A Pshycholinguistic Study
Authors: Humaini Arif , Nurdianto Talqis
Published: November 2024

This research was motivated by the increasingly widespread discussion of CEFR lea rning methods as a reference for Arabic language learning in Indonesia. A language teaching framework must always be developed in such a way that learning objectives can be achieved. This study focused on the level of understanding rather than the CEFR. This study aims to provide additional insight into academic treasures by reviewing CEFR learning references from a Psycholinguistic point of view. In the psycholinguistic view, it is explained that there are two processes in the mechanism of language in humans, namely receptive and productive, the process of receiving speech and producing speech. At the receiving stage, there will be an understanding process which is categorized by the CEFR as a comprehension level stage consisting of two proficiency activities, namely listening and reading skills. The production process is categorized in the level of speaking and writing proficiency. In addition, the category of foreign languages such as Arabic in the acquisition of language from a psycholinguistic perspective is included in the category of second language acquisition, which is the language mastered by the speaker of a particular language after he has mastered the first language. The approach used in this study is a qualitative approach using document analysis or library research.
Dictation Technique in Hiragana Writing: Implementation and Result
Authors: Wahyuni Yuli , Indraswari Thamita Islami
Published: November 2024

Mastering Hiragana is a necessity for all students majoring in Japanese, but the students often find it challenging to write Hiragana words. This study explores students’ difficulties in writing Hiragana by implementing dictation techniques in Hiragana learning. Through qualitative descriptive methods and exploring data gathered from 26 first-year students majoring in Japanese Language Education at Universitas Muhammadiyah Yogyakarta, the findings showed that the dictation technique, one of the oldest learning techniques, is still pertinent in modern learning. It can also be utilized not only as a tool in teaching hiragana words but also as a tool for identifying students’ difficulties in writing hiragana words. Findings showed that the students face difficulties distinguishing hiragana letters that look similar (such as A and O), impacting their ability to write the correct word. The students also faced difficulties in writing words containing long sounds and remembering their rules (when to write OO instead of OU, to write EI instead of EE), writing words containing ZU sounds, writing words containing TSU sounds, writing words that were unfamiliar to the students but contained similar sounds (such as TSUMAMI compared to TSUNAMI, BIYOIN compared to BYOUIN), writing words that contain more than three syllables.
Role of Technology in Facilitating International Student Mobility: Systematic Literature and Mapping Study Approaches
Authors: Aprizal Anggi , Wiranatakusuma Dimas Bagus , Rizki Mochamad , Sari Mariska Intan , Al Zahra Monica Kis , Zainal Zalina
Published: November 2024

Programs for student mobility have grown in importance as part of international higher education. as technology develops, student mobility programs also go through major changes that affect how these programs are created, conducted, and accessed. This research reviews literature related to student mobility programs and technological use published in the reputable international journal Scopus. This methodology uses a systematic literature review and mapping study approach. The results of the review show that the trends in using technology for student mobility program activities are related to skills, personal maturity, professionalism and self-confidence while providing provisions for building student careers. Apart from that, technology in student mobility program activities is benefited in terms of governance of mobility programs. In addition, future trends related to studies of the relationship between technology and student mobility programs are related to issues of academic outcomes, school climate, customer analytics, and global skill opportunities. Therefore, this study is significant for exploring the linkage between technology use and pursuing student mobility programs.
Measuring Motivation: A Statistical Lens on Gender Differences in Online Reading Activities
Authors: Puspitasari Evi , Ghozy Adhajaya Reisnanda , Ariebowo Teguh
Published: November 2024

When it comes to online reading activities, every student has a different motivation to read, particularly male and female students. The purpose of this study was to test the hypothesis (H1) saying that there is a significant difference between male and female students’ motivations in reading online. 31 male and 72 female students from ED of Sunville University, Indonesia are samples used in this quantitative study. To collect data, the researcher employed a questionnaire that was modified from Wigfield and Guthrie (1997). According to the data, male students’ reading motivation averages 2.58, while female students’ averages are 2.78 in using online platforms. The average score obtained from gender demonstrates a positive attitude. If the 2-tailed Sig. value is less than 0.05, a significant difference exists between male and female students’ reading motivations. This study has figures (.027) showing a significant difference between women and men in reading motivation. Thus, the H1 is accepted This suggests that the females and males have a different motivation level in reading online.
Intrahepatic Cholangiocarcinoma Presenting as an Incidentaloma on F-18 PYL PSMA PET/CT
Authors: Patel Rishi R. , Grewal Udhayvir Singh , Xiong Yiqin , Fei Naomi
Published: November 2024

Cholangiocarcinoma is an aggressive malignancy arising from the biliary tract epithelium with rising incidence and mortality. Imaging commonly used for diagnostic workup includes computed tomography (CT) scan and magnetic resonance imaging (MRI). Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) scans can be used for investigating equivocal findings on radiographic imaging. Prostate-specific membrane antigen (PSMA) is known to be highly expressed in prostate adenocarcinoma, allowing it to be leveraged as a target for both imaging and radioligand therapy in prostate cancer. However, PSMA is also commonly expressed in other malignancies such as breast cancer, thyroid carcinomas, and head and neck malignancies, which increase the chances of their incidental diagnosis on PSMA PET scans. Biliary tract cancers, including cholangiocarcinoma, are not commonly expected to be incidentally diagnosed on PSMA PET imaging. Here, we describe the case of a patient with known prostate adenocarcinoma who was later incidentally diagnosed with advanced intrahepatic cholangiocarcinoma on PSMA PET/computed tomography (CT). This case highlights the unexpected finding of cholangiocarcinoma on PSMA PET/CT and suggests further investigation into the role of PSMA PET in diagnosing ambiguous cases of cholangiocarcinoma and its potential theranostic applications.
Low-temperature structural phase transition in cesium-dysprosium molydate
Authors: Zvyagin A. I. , El'chaninova S. D. , Stetsenko T. S. , Pelikh L. N. , Khatsko E. N.
Published: November 2024

Studies on the temperature dependences of the IR absorption spectrum and magnetic susceptibility of CsDy(MoO4)2 revealed a structural phase transition at a temperature of ∼38°K. The phase transition is accompanied by a temperature hysterisis in the range of ∼ 1 °C, and is apparently a transition of the first kind.
Problem of generation of current oscillations in bismuth
Authors: Bogod Yu. A. , Valeev R. G. , Onokienko G. P.
Published: November 2024

It is shown that the frequency of the damped current oscillations in bismuth at 20.4°K discovered previously by Bogod, Valeev, and Onokienko is determined by the dimension of the sample d in the direction [E × H]. With a given value of the current passing through the sample, and with other conditions being equal, the amplitude of the oscillations depends on the shape of the input signal, and the attenuation is determined, to a considerable degree, by its derivative with respect to time. A nonmonotonic dependence is observed for the amplitude of the oscillations on the rate of change of the input signal when it is increased. At 20.4°K, undamped oscillations are observed with a frequency of ≈4(s/d).
Effect of working fluid temperature on flow characteristics of jet cavitation reactor
Authors: Gou Jinlan , Xiao Qi , Zou Zhenhai , Li Bangming
Published: November 2024

The huge amount of energy generated by cavitation in liquids can be used to achieve more ecologically friendly and efficient removal of algae. Jet pumps readily induce cavitation owing to their tapering section structure and thus have the potential to be used as jet cavitation reactors (JCRs) to achieve hydrodynamic cavitation and algal removal under suitable pressure conditions. In this paper, we examine the cavitation characteristics of a JCR at different working fluid temperatures, using large eddy simulation. The vortex structure created by high-speed jets at the nozzle of the JCR is continuous and orderly, whereas the downstream vortex structure becomes chaotic and fragmented under the actions of flow mixing and bubble development. An increase in water temperature can reduce vorticity. As the water temperature rises, the cavitation number decreases, the total cavity volume increases, and cavitation changes from an unstable to a stable limit state. When cavitation is in its unstable limit state, the total bubble volume exhibits quasi-periodic changes and the cavitation cloud pulsates strongly, while when cavitation is in its stable limit state, cavitation cloud pulsation is seen only at the outlet.
Co-evolutionary dynamics for two adaptively coupled Theta neurons
Authors: Augustsson Felix , Martens Erik A.
Published: November 2024

Natural and technological networks exhibit dynamics that can lead to complex cooperative behaviors, such as synchronization in coupled oscillators and rhythmic activity in neuronal networks. Understanding these collective dynamics is crucial for deciphering a range of phenomena from brain activity to power grid stability. Recent interest in co-evolutionary networks has highlighted the intricate interplay between dynamics on and of the network with mixed time scales. Here, we explore the collective behavior of excitable oscillators in a simple network of two Theta neurons with adaptive coupling without self-interaction. Through a combination of bifurcation analysis and numerical simulations, we seek to understand how the level of adaptivity in the coupling strength, a, influences the dynamics. We first investigate the dynamics possible in the non-adaptive limit; our bifurcation analysis reveals stability regions of quiescence and spiking behaviors, where the spiking frequencies mode-lock in a variety of configurations. Second, as we increase the adaptivity a, we observe a widening of the associated Arnol’d tongues, which may overlap and give room for multi-stable configurations. For larger adaptivity, the mode-locked regions may further undergo a period-doubling cascade into chaos. Our findings contribute to the mathematical theory of adaptive networks and offer insights into the potential mechanisms underlying neuronal communication and synchronization.
Improvement on the screening of nonlinear commutator operations in selective coupled-cluster using Lagrangian
Authors: Basumallick Suhita , Xu Enhua , Ten-no Seiichiro L.
Published: November 2024

We introduce a Lagrangian implementation of the full coupled-cluster reduction [Xu et al., Phys. Rev. Lett. 121, 113001 (2018)], that is, a selected coupled-cluster (CC) based on an arbitrary-order full CC expansion using direct commutator expansions. In this method, the screening for the products of cluster amplitudes plays a central role to reduce the computational cost for the nonlinear commutator operations, while the convergence of the total energy in the standard energy expression is not rapid with tightening the threshold. The new implementation using Lagrangian is robust, containing error only quadratic to those of amplitudes, allowing a much larger screening threshold. We demonstrate the performance of the new implementation by investigating the calculations of N2 and C6H6. The accuracy and applicability are also demonstrated for the potential energy curve of H2O in comparison with conventional quantum chemical methods.
Rheological behavior of amine-functionalized liquid polybutadiene
Authors: Malmir Amir , Ataie Saeed , Yavitt Benjamin M. , Schafer Laurel L. , Hatzikiriakos Savvas G.
Published: November 2024

Varying quantities of hydrogen-bonding stickers (amines) are introduced to liquid polybutadiene through the hydroaminoalkylation method. Amination significantly affects both the glassy and rubbery dynamics of these materials. The amination process results in a delay of the transition from the glassy to rubbery state, attributed to the lower mobility of hydrogen-bonding sites compared to the backbone segments. As the density of stickers increases, a liquid to solid transition is observed, and the emergence of a plateau rubbery modulus due to hydrogen bonding between amine functional groups. Rheological analysis reveals a failure in time-temperature superposition near the gel point. This failure is due to the decrease in the intensity of the elastically effective network strands with rising temperature from the weakening of the strength of hydrogen bonds. Moreover, the terminal relaxation timescale lengthens considerably as the degree of gelation increases, indicating the impact of many cooperative intermolecular associations. Compared to high molecular weight polybutadiene, the functionalized low molecular weight polybutadienes possess similar plateau modulus, highlighting the effectiveness of post-polymerization modifications in enhancing the mechanical properties of the amine-functionalized low molecular weight polybutadiene.
Enhanced tungsten wire energy deposition during copper–tungsten intertwined electrical explosion in atmospheric air
Authors: Li Tuan , Shi Huantong , Wang Tongquan , Zhang Peizhou , Wang Dongsheng , Hu Yujia , Wu Jian , Li Xingwen
Published: November 2024

Intertwined electrical wire explosion (EWE) is considered as a potential method for large-scale synthesis of high-entropy alloy nanoparticles, while the helical structure, close contact, and different electrothermal properties of wires add to the difficulties of controlling the Joule energy distribution among the wires. In this paper, two very dissimilar materials, copper and tungsten, are chosen as representatives of nonrefractory and refractory metals, and the Cu–W intertwined EWE is compared to parallel EWE of spaced straight Cu and W wires. It is found that for the intertwined load, the majority of the tungsten wire is located in the center and encapsulated by copper vapor, with a low-density spiral plasma belt surrounding the exploding product, and the tungsten wire is transformed into a highly vaporized state instead of a typical core–corona structure, with expansion velocity ∼1.8 times and average energy deposition more than three times that of the parallel load. This dramatic difference is attributed to the high-density and high-pressure vapor medium created by early explosion of the copper wire, which surrounds the tungsten wire and suppresses the formation and expansion of conductive surface plasma channel. These findings can serve to improve the load design for achieving simultaneous dispersion and uniform mixing of dissimilar materials via intertwined EWE.
Dimensional analysis of diffusive association rate equations
Authors: Chen Jixin
Published: November 2024

Diffusive adsorption/association is a fundamental step in almost all chemical reactions in diluted solutions, such as organic synthesis, polymerization, self-assembly, biomolecular interactions, electrode dynamics, catalysis, chromatography, air and water environmental dynamics, and social and market dynamics. However, predicting the rate of such a reaction is challenging using the equations established over 100 years ago. Several orders of magnitude differences between the theoretical predictions and experimental measurements for various systems, from self-assembled monolayers to protein-protein aggregations, make such calculations meaningless in many situations. I believe the major problem is that the time-dependent evolution curve of Fick’s gradient is an ideal assumption in most cases, and its slope is significantly overestimated. This paper digs into Fick’s gradient problem for 3D cases and provides a solution using the single-molecule diffusion probability density function discretely.
Impact of mechanical tolerances on partial turn skipping in helical flux compression generator
Authors: Schriner K. , Fryar N. , Watson T. , Stephens J. , Dickens J. , Young A. , Neuber A.
Published: November 2024

Maintaining tight mechanical tolerances of the components used in helical flux compression generators is crucial for optimizing device performance. Moving beyond current literature, which provides various approximations for acceptable tolerances, a 3D simulation of the armature stator interaction during generator operation was developed, revealing that existing equations frequently misestimate the tolerance limits. Without restricting the generality of the presented approach, the focus was primarily on the armature’s concentricity and roundness, comparing the acceptable tolerance limits between generators of different sizes. An analytical approach for select geometries was developed, confirming the 3D results. Quantitative results reveal that a steeper Gurney angle and increased winding pitch allow for less restrictive tolerances for eccentricity and ellipticity. Even small deviations from the ideal armature positioning and shape will result in fluctuations of the output current time-derivative, observed experimentally and in simulation. Larger deviations then cause partial turn skipping, associated with loss of magnetic flux. The simulation elucidates the impact of tolerance deviations on generator performance by offering precise tolerance ranges for various generator sizes, thereby facilitating informed design decisions.
A priori assessment of a simple approach to evaluating burning rate in large eddy simulations of premixed turbulent combustion
Authors: Lipatnikov Andrei N.
Published: November 2024

This paper aims at assessing a hypothesis that resolution required to evaluate fuel consumption and heat release rates by directly (i.e., without a subgrid model of unresolved influence of small-scale turbulent eddies on the local flame) processing filtered fields of density, temperature, and species mass fractions should be significantly finer than resolution required to directly compute flame surface density by processing the same filtered fields. For this purpose, box filters of various widths Δ are applied to three-dimensional direct numerical simulation data obtained earlier from a statistically one-dimensional and planar, moderately lean H2/air complex-chemistry flame propagating in a box under conditions of sufficiently intense small-scale turbulence (Karlovitz number is larger than unity, and a ratio of laminar flame thickness δL to Kolmogorov length scale is about 20). Results confirm this hypothesis and show that the mean flame surface density and area can be predicted with acceptable accuracy by processing filtered combustion progress variable fields computed using a sufficiently wide filter, e.g., Δ/δL=4/3. Such an approach does not require a model of the influence of subgrid turbulent eddies on flame surface density provided that Δ and δL are of the same order of magnitude. Good performance of this approach is attributed to inability of small-scale (when compared to δL) turbulent eddies to substantially change the local flame structure, which, nevertheless, is significantly perturbed by larger turbulent eddies that strain the local flame.
Monocytes give rise to Langerhans cells that preferentially migrate to lymph nodes at steady state
Authors: Raquer-McKay Hayley M. , Maqueda-Alfaro Raul A. , Saravanan Sanjana , Arroyo Hornero Rebeca , Clausen Björn E. , Gottfried-Blackmore Andres , Idoyaga Juliana
Published: November 2024

Current evidence suggests that ontogeny may account for the functional heterogeneity of some tissue macrophages, but not others. Here, we asked whether developmental origin drives different functions of skin Langerhans cells (LCs), an embryo-derived mononuclear phagocyte with features of both tissue macrophages and dendritic cells. Using time-course analyses, bone marrow chimeras, and fate tracing models, we found that the complete elimination of embryo-derived LCs at steady state results in their repopulation from circulating monocytes. However, monocyte-derived LCs inefficiently replenished the epidermal niche. Instead, these cells preferentially migrated to skin-draining lymph nodes. Mechanistically, we show that the enhanced migratory capability of monocyte-derived LCs is associated with higher expression of CD207/Langerin, a C-type lectin involved in the capture of skin microbes. Our data demonstrate that ontogeny plays a role in the migratory behavior of epidermal LCs.
Engaging children in activities and interactions
Authors: Masson Caroline , Bertin Tiphanie , Martel Karine , Salazar Orvig Anne , da Silva-Genest Christine , Chartier Eloïse
Published: November 2024

In early childhood education and care (ECEC), children do not
participate in the same way and to the same extent in various kinds of
interactions. One of the challenges for educators is to succeed in involving
every child in the proposed activities, thereby enabling them to benefit from
these experiences for language acquisition. The present exploratory study was
conducted through video recordings of educator-child interactions in French
ECEC contexts. The analysis focused on sequences where one or more children
either withdrew or stayed in the background of the ongoing activities. The
sequences were categorised according to the type of activity, the educators’
language strategies, and their outcomes in terms of the children’s
participation. By focusing on the role and impact of language practices, our
discussion re-examines the notion of involvement/engagement, its achievements in
ECEC, and the effects of the educators’ moves on child involvement.
Trace-free Einstein gravity as two interacting constrained BF theories
Authors: Montesinos Merced , Gonzalez Diego
Published: November 2024

A theory of gravity alternative to general relativity is trace-free Einstein gravity, which has the remarkable property that the cosmological constant emerges as an integration constant. In this paper, we report two fully diffeomorphism-invariant actions for trace-free Einstein gravity. They describe the theory as two BF theories supplemented with some constraints. The first action comprises two copies of the constrained BF theory for the Husain–Kuchař model plus an interaction term involving the fields that impose the constraints on the B fields. The second action employs two copies of the chiral Plebanski action for general relativity plus an additional constraint. Both actions use complex variables, and naturally include one of the reality conditions imposed in the Plebanski formulation of general relativity. The new actions have the advantage of not involving any nondynamical fields or unimodular condition, and their only gravitational sector is trace-free Einstein gravity.
Stability analysis and improvement of the covariant BSSN formulation against the FLRW spacetime background
Authors: Hoshino Hidetomo , Tsuchiya Takuya , Yoneda Gen
Published: November 2024

In this study, we investigate the numerical stability of the covariant Baumgarte–Shapiro–Shibata–Nakamura (cBSSN) formulation against the Friedmann–Lemaitre–Robertson–Walker spacetime. To evaluate the numerical stability, we calculate the constraint amplification factor by the eigenvalue analysis of the evolution of the constraint. We propose a modification to the time evolution equations of the cBSSN formulation for higher numerical stability. Furthermore, we perform numerical simulations using the modified formulation to confirm its improved stability.
Nonlinearity helps the convergence of the inverse Born series
Authors: DeFilippis Nicholas , Moskow Shari , Schotland John C
Published: November 2024

In previous work of the authors, we investigated the Born and inverse Born series for a scalar wave equation with linear and nonlinear terms, the nonlinearity being cubic of Kerr type (DeFilippis et al 2023 Inverse Problems
39 125015). We reported conditions which guarantee convergence of the inverse Born series, enabling recovery of the coefficients of the linear and nonlinear terms. In this work, we show that if the coefficient of the linear term is known, an arbitrarily strong Kerr nonlinearity can be reconstructed, for sufficiently small data. Additionally, we show that similar convergence results hold for general polynomial nonlinearities. Our results are illustrated with numerical examples.
Photoluminescence intensity enhancement of nanorod micro-LEDs via localized surface plasmon coupling
Authors: Du Zaifa , Fang Aoqi , Tang Penghao , Fan Xinmin , Sun Jie , Guo Weiling , Wang Yan , Zhang Jianxin
Published: November 2024

Nano-light-emitting diodes (LEDs) are ideal for ultra-high resolution displays due to their small size and high pixel density. However, traditional photolithography techniques fall short in meeting the requirements for nanoscale LED fabrication. Besides, as the size decreases and the specific surface area increases, non-radiative recombination generated by sidewalls defects becomes a significant issue, affecting the efficiency of nano-LEDs. To address this challenge, a nano-LED array with a single nanorod size of 800 nm was fabricated in this work by using nanosphere lithography and etching technology. Meanwhile, localized surface plasmons (LSPs) coupling technology was employed to enhance the PL efficiency of these nano-LEDs. By comparing with bare nano-LEDs, the PL intensity was boosted by about 43% and 129% when Ag and Ag@SiO2 nanoparticles were added separately. The existence of LSPs coupling process has been further confirmed through time-resolved photoluminescence measurement and finite element simulation analysis of different samples. The results provide compelling evidence for the LSPs coupling technology in enhancing the efficiency of nanoscale LEDs.
Finite-frequency noise, Fano factor, ΔT-noise and cross-correlations in double quantum dots
Authors: Crépieux A , Duong T Q , Lavagna M
Published: November 2024

A theoretical study on electrical current fluctuations in a double quantum dot connected to electronic reservoirs is presented, with the aim of deriving the finite-frequency noise, the Fano factor and the ΔT-noise. We establish a general expression for the noise in terms of Green functions in the double quantum dot and self-energies in the reservoirs. This result is then applied to model double quantum dots in various situations. For a non-interacting double quantum dot, we highlight several interesting features in the physical properties of this system. In particular, we demonstrate the possibility of obtaining a significant reduction in zero-frequency noise and Fano factor either when the system is placed in a given operating regime, or when a temperature gradient is applied between the two reservoirs, resulting in a negative ΔT-noise being generated. In addition, in the vicinity of honeycomb vertices, a sign change is observed in the finite-frequency cross-correlator between the two reservoirs, in contrast to what is obtained for the zero-frequency cross-correlator, which remains negative throughout the

(

ε
1

,

ε
2

)

-plane,

ε

1
,
2

being the level energies in each of the two dots. By using an approximate first-level numerical approach, we finally study how the finite-frequency noise in a double quantum dot evolves under the influence of Coulomb interactions.
On the Hausdorff dimension and Cantor set structure of sliding Shilnikov invariant sets
Authors: Cunha Matheus G C , Novaes Douglas D , Ponce Gabriel
Published: November 2024

The concept of sliding Shilnikov connection has been recently introduced and represents an important notion in Filippov systems, because its existence implies chaotic behavior on an invariant subset of the system. The investigation of its properties has just begun, and understanding the topology and complexity of its invariant set is of interest. In this paper, we conduct a local analysis on the first return map associated to a sliding Shilnikov connection, which reveals a conformal iterated function system (CIFS) structure. By using the theory of CIFS, we estimate the Hausdorff dimension of the local invariant set of the first return map, showing, in particular, that is a positive number smaller than 1, and with one-dimensional Lebesgue measure equal to zero. Moreover, we prove that the closure of the local invariant set is a Cantor set and retains both the Hausdorff dimension and Lebesgue measure of the local invariant set. Furthermore, this closure consists of the local invariant set along with the set of all pre-images, under the first return map, of the visible fold-regular point contained in the connection.
A first-principle study on the band structure of GePb alloys
Authors: Xia Shilong , Yu Jiulong , Wang Jinghang , Huang Wei , Wen Yuhua , Li Cheng , Li Jun , Chen SongYan
Published: November 2024

Single crystal GePb alloys have been considered as potential direct bandgap materials for optoelectronics application. In this work, density-functional theory calculations were performed to investigate the crystalline and electronic structures of the GePb alloys. The lattice constants of the unstrained GePb alloys are found positively deviating from Vegard’s law with a bowing coefficient of 0.587 Å. GePb has a higher Poisson’s ratios than GeSn with a similar alloying concentration. With the increasing Pb concentration x in Ge1−x
Pb
x
, a new alloying energy level brought by Pb appears at the bottom of the conduction band and continuously decreases. The new energy level is constructed to a new valley as compared to the initial Γ valley and the new energy level is acquiring its higher spectra weights with increasing Pb concentration. An indirect-to-direct bandgap transition occurs with a Pb concentration of 3.3%. The effective masses of holes and electrons in the GePb Γ valley are calculated to decrease with the increasing Pb concentration, while the effective masses of the electrons in the L valley only change slightly. The small effective masses of the electrons in the Γ valley are favorable for high-speed GePb device application.
Theoretical investigation to study the influence of strain on the band lineups of core/shell nanostructures
Authors: Paul Payal , Chattopadhyay Saikat , Biswas Joydeep , Kabi Sanjib
Published: November 2024

A class of quantum dots (QD) known as core–shell quantum dots (CSQDs) where a lower band gap material is enclosed by a higher band gap material, are highly confined nanoparticles, that project altered properties like enhanced carrier confinement, stability, and reduced recombination. The strain generated, due to the formation of a heterojunction-like structure near the CSQD boundary, has a direct impact on its opto-electronic properties by altering the band positions of the materials. In this work, we aimed to understand the impact of strain generated near such heterojunction due to the presence of two different materials as core and shell on its optical band lineup to comprehend the observed enhanced optical properties of such structures. Here, we have assumed a general model comprising ZnTe core surrounded by a ZnSe shell. Initially, to start, the CSQD structure was considered with a core size of 3 nm and a shell of 1.2 nm. A crossover from type-I to type-II in optical band line up was observed with an increase in shell thickness. The estimated value of the highest conduction band offset ∼60% was obtained for a shell width of 1.2 nm, i.e. the unstrained state, while the largest valence band offset ∼100% was obtained for the shell width of 1 nm.
Multi-station Meteor Monitoring (M3) System. II. System Upgrade and a Pathfinder Network
Authors: Li Zhenye , Zou Hu , Liu Jifeng , Ma Jun , Meng Qingyu , Cai Yingjie , Zhao Xinlin , Li Xue , Tu Zhijun , Zhang Bowen , Wang Rui , Wang Shaohan , Feng Lu
Published: November 2024

Meteors are important phenomena reflecting many properties of interplanetary dust particles. The study of their origin, mass distribution, and orbit evolution requires a large data volume, which can only be obtained using large meteor networks. After meteor networks in Europe and America, we present our designs and upgrades of a proposed network in China. The new designs are mainly aimed at facilitating the data gathering process. Each of the newly designed meteor stations can now support up to four cameras to cover the full sky. A newer version of the meteor station software now works as an integral system, which can streamline the process of detecting, measuring, and uploading meteors. We have built a meteor data platform to store, process, and display the meteor data automatically. The software and data platform are designed to be easy to learn and use, so they can attract more people to join and operate meteor stations. Four stations are installed as the first phase of the network, and during the operation, in 10 months, the network detected 8683 orbits; we find that half of the orbits can be related to established meteoroid streams. The statistical analysis of sporadic meteoroids shows a bimodal distribution of the velocities, which coincides with previous studies. The distribution of Tisserand parameters, T

j
, shows the two peaks at T

j
= 0 and 3, indicating the different orbits of parent bodies (isotropic and ecliptic), which are divided by T

j
= 2. The falling trajectory of a meteorite was also predicted using the observational data of the network. We are currently expanding the network, and in the future, we will carry out a detailed analysis of the key parameters of the distribution of the meteoroids.
Electronic band structures of topological kagome materials
Authors: Li 李 Man 满 , Ma 马 Huan 欢 , Lou 娄 Rui 睿 , Wang 王 Shancai 善才
Published: November 2024

The kagome lattice has garnered significant attention due to its ability to host quantum spin Fermi liquid states. Recently, the combination of unique lattice geometry, electron–electron correlations, and adjustable magnetism in solid kagome materials has led to the discovery of numerous fascinating quantum properties. These include unconventional superconductivity, charge and spin density waves (CDW/SDW), pair density waves (PDW), and Chern insulator phases. These emergent states are closely associated with the distinctive characteristics of the kagome lattice’s electronic structure, such as van Hove singularities, Dirac fermions, and flat bands, which can exhibit exotic quasi-particle excitations under different symmetries and magnetic conditions. Recently, various quantum kagome materials have been developed, typically consisting of kagome layers stacked along the z-axis with atoms either filling the geometric centers of the kagome lattice or embedded between the layers. In this topical review, we begin by introducing the fundamental properties of several kagome materials. To gain an in-depth understanding of the relationship between topology and correlation, we then discuss the complex phenomena observed in these systems. These include the simplest kagome metal T
3
X, kagome intercalation metal TX, and the ternary compounds AT
6
X
6 and RT
3
X
5 (A = Li, Mg, Ca, or rare earth; T = V, Cr, Mn, Fe, Co, Ni; X = Sn, Ge; R = K, Rb, Cs). Finally, we provide a perspective on future experimental work in this field.
Gyrokinetic simulation of the interplay between ion temperature gradient turbulence and reversed shear Alfvén Eigenmodes
Authors: Yang Yuheng , Ye Lei , Chen Yang , Xiang Nong , Sun Youwen
Published: November 2024

A nonlinear gyrokinetic simulation, which incorporates both the reversed shear Alfvén eigenmode (RSAE) and the ion temperature gradient (ITG) turbulence, has been performed using the electromagnetic gyrokinetic Particle-In-Cell (PIC) code GEM. Strong nonlinear wave coupling and energy transfer between RSAE and ITG turbulence have been observed. Specific analyses show that the n = 4 Alfvén eigenmode primarily interacts with the ITG harmonics with long wavelength (

n
⩽
16

). It is found that a background ITG turbulence can suppress the saturation level of RSAE and change the energetic particle transport. The frequency up-shift of RSAE and the frequency modulation on ITG components by RSAE are also observed. The impacts of the initial condition on the RSAE-ITG turbulence simulation are also discussed.
Direct and semi-direct aerosol effects on the scaling of extreme sub-daily precipitation over East China
Authors: Li Shuping , Su Tao , Xiang Ruolan , Schär Christoph
Published: November 2024

Aerosols can alter atmospheric stability through radiative forcing, thereby changing mean and daily extreme precipitation on regional scales. However, it is unclear how extreme sub-daily precipitation responds to aerosol radiative effects. In this study, we use the regional climate model (RCM) Consortium for Small-scale Modeling (COSMO) to perform convection-permitting climate simulations at a kilometer-scale (0.04°/~4.4 km) resolution for the period 2001–2010. By evaluating against the observed hourly precipitation-gauge data, the COSMO model with explicit deep convection can effectively reproduce sub-daily and daily extreme precipitation events, as well as diurnal cycles of summer mean precipitation and wet hour frequency. Moreover, aerosol sensitivity simulations are conducted with sulfate and black carbon aerosol perturbations to assess the direct and semi-direct aerosol effects on extreme sub-daily precipitation in the COSMO model. The destabilizing effects associated with decreased sulfate aerosols intensify extreme sub-daily precipitation, while increased sulfate aerosols tend to induce an opposite change. In contrast, the response of extreme sub-daily precipitation to black carbon aerosol perturbations exhibits a nonlinear behavior and potentially relies on geographical location. Overall, the scaling rates of extreme precipitation intensities decrease and approach the Clausius–Clapeyron rate from hourly to daily time scales, and the responses to sulfate and black carbon aerosols vary with precipitation durations. This study improves the understanding of aerosol radiative effects on sub-daily extreme precipitation events in RCMs.