Analytical Findings Research Articles

Analyzing the dynamic patterns of COVID-19 through nonstandard finite difference scheme

This paper presents a novel approach to analyzing the dynamics of COVID-19 using nonstandard finite difference (NSFD) schemes. Our model incorporates both asymptomatic and symptomatic infected individuals, allowing for a more comprehensive understanding of the epidemic's spread. We introduce an unconditionally stable NSFD system that eliminates the need for traditional Runge–Kutta methods, ensuring dynamical consistency and numerical accuracy. Through rigorous numerical analysis, we evaluate the performance of different NSFD strategies and validate our analytical findings. Our work demonstrates the benefits of using NSFD schemes for modeling infectious diseases, offering advantages in terms of stability and efficiency. We further illustrate the dynamic behavior of COVID-19 under various conditions using numerical simulations. The results from these simulations demonstrate the effectiveness of the proposed approach in capturing the epidemic's complex dynamics.

Analysis of Prey-Predator Scheme in Conjunction with Help and Gestation Delay

This paper presents a three-dimensional continuous time dynamical system of three species, two of which are competing preys and one is a predator. We also assume that during predation, the members of both teams of preys help each other and the rate of predation of both teams is different. The interaction between prey and predator is assumed to be governed by a Holling type II functional response and discrete type gestation delay of the predator for consumption of the prey. In this work, we establish the local asymptotic stability of various equilibrium points to understand the dynamics of the model system. Different conditions for the coexistence of equilibrium solutions are discussed. Persistence, permanence of the system, and global stability of the positive interior equilibrium solution are discussed by constructing suitable Lyapunov functions when the gestation delay is zero, and there is no periodic orbit within the interior of the first quadrant of state space around the interior equilibrium. As we introduced time delay due to the gestation of the predator, we also discuss the stability of the delayed model. It is observed that the existence of stability switching occurs around the interior equilibrium point as the gestation delay increases through a certain critical threshold. Here, a phenomenon of Hopf bifurcation occurs, and a stable limit cycle corresponding to the periodic solution of the system is also observed. This study reveals that the delay is taken as a bifurcation parameter and also plays a significant role for the stability of the proposed model. Computer simulations of numerical examples are given to explain our proposed model. We have also addressed critically the biological implications of our analytical findings with proper numerical examples.

Highly dispersive optical solitons with differential group delay for Sasa-Satsuma equation having multiplicative white noise

AbstractThis paper is about the retrieval of highly dispersive optical solitons for Sasa-Satsuma equation with differential group delay in presence of white noise. There are four integration schemes that make this retrieval possible. A full spectrum of optical solitons have been revealed from these schemes. The parametric restrictions for the existence of such solitons are also presented. The displayed surface plots support the analytical findings.

Adaptive bipartite output containment control of heterogeneous multi‐agent systems against FDI attacks

AbstractThis paper researches the adaptive bipartite output containment control of heterogeneous multi‐agent systems (HMASs) against false data injection (FDI) attacks. The malicious adversaries could inject attacks on the actuator to maximize damage to the HMASs, which in turn causes the compromised followers to be unable to track the output states of the leaders. To address this issue, a resilient layer is introduced that prevents attack signals from affecting the states. Moreover, an adaptive compensator is ingeniously devised to counteract these attacks, thereby ensuring that both cooperative and antagonistic agents adhere to distinct convex hulls. Leveraging the output regulation approach, conducting Lyapunov stability analysis, and drawing upon other pertinent methodologies, we have systematically constructed a robust framework for the realization of bipartite output containment control. Ultimately, the validity of the analytical findings is confirmed through a series of rigorous numerical simulations.

Performance analysis of 5G and beyond mixed THz/FSO relaying communication systems

This paper explores the potential of relay-assisted transmission to mitigate fading in free-space optical (FSO) systems. Our investigation focuses on assessing the performance of a dual-hop relay system for Terahertz/FSO (THz/FSO) communication. We develop an aggregated channel model incorporating various factors, including pointing errors, channel fading, and deterministic path loss. Specifically, the THz link encounters α−μ fading with pointing errors, while the FSO link experiences Gamma–Gamma fading and pointing errors. We utilize amplify-and-forward relaying and derive mathematical expressions for the probability density function and cumulative distribution function of the end-to-end signal-to-noise ratio, considering the combined effects of channel fading and pointing errors. Employing the derived statistical expressions, we evaluate crucial performance metrics for the considered relaying schemes, including the outage probability and the average bit error rate. To validate our analytical findings, we conducted Monte-Carlo simulations. The results demonstrate a strong correlation between the performance of the system and the particular pointing errors and fading parameters linked to the THz/FSO connections.

Long-term equilibrium in electricity markets with renewables and energy storage only

AbstractIn this paper, we study the optimal generation mix in power systems where only two technologies are available: variable renewable energy (VRE) and electric energy storage (EES). By using a net load duration curve approach, we formulate a least-cost optimization model in which EES is only limited by its power capacity. We solve this problem analytically and find least-cost and market equilibrium conditions that lead to the optimal capacities of VRE and EES. We show that, mathematically, an electricity price structure that depends on the period of the year (i.e. EES charging or discharging, VRE curtailment, load shedding) and on investments costs leads to cost recovery for VRE and EES. We show that when EES is the marginal technology (either charging or discharging) the price must be non-zero. More specifically, the equilibrium prices during EES charge or discharge are functions of the EES and VRE fixed costs. We confirm our analytical findings using a numerical model. We argue that, although the system we study is hypothetical and simplified, our findings provide insights and research directions for how to recover fixed costs in a future electricity market based on VRE and EES only.

Performance analysis of energy harvesting‐enabled relay networks in κ‐μ fading channels

AbstractIn this paper, we investigate the performance of an energy harvesting (EH)‐enabled multiple relay network operating over generalized ‐ fading channels. Our approach involves utilizing a partial relay selection strategy and employing an amplify and forward relay protocol for efficient EH from RF signals. Additionally, we integrate a selection combining scheme at the receiver to combine both direct and relaying path signals. In our research, we first obtain the exact closed‐form expression of the cumulative distribution function (CDF) for the system under investigation. Subsequently, we derive expressions for the outage probability (OP) and the moment generating function (MGF) using the derived CDF expression. Furthermore, with the assistance of a CDF‐based approach, we derive closed‐form expressions for the average symbol error rate (ASER) for coherent quadrature amplitude modulation (QAM) schemes, including rectangular QAM (RQAM) and hexagonal QAM (HQAM). We also analyze the ASER expression for non‐coherent frequency shift keying (NCFSK), leveraging the derived MGF expression. To gain valuable insights into the performance of EH‐enabled multiple relay networks, we assess the asymptotic expression of the OP. The outcomes indicate how the behavior of the system is affected by various factors such as time switching ratio, channel fading components, number of relays, and the distance between nodes. To corroborate the accuracy of the analytical findings, Monte Carlo simulations are executed.

A Mathematical Modeling of the Vaccination Effect on the SARS-CoV-2 Transmission: Analysis and Simulation

     Several illustrative studies on the mathematical modeling and analysis of the Coronavirus have been carried out in a short period of time. There is not enough work that accounts for the vaccination campaign's two stages. In this work, a mathematical model is created to show the impact of the recent two-stage vaccination treatment on the Coronavirus. In the proposed model, five compartments are constructed, namely the susceptible individuals , the first dose of vaccination  , the second dose of vaccination , infected  and recovered population . The uniqueness, boundedness and existence of the solutions of this model have been discussed. All potential model equilibrium points are determined. The local as well as global stability of the system in terms of the basic reproduction number is investigated. Numerical simulation is also carried out to investigate the influence of parameters affecting the dynamics of the model and to support the gathered analytical findings of the model.

Technical Note—Production Management with General Demands and Lost Sales

Analyzing Production-Inventory Systems with General Demand: Cost Minimization and Risk Analytics Frequent production rate changes are prohibitive because of high setup costs or setup times in producing such items as sugar, glass, computer displays, and cell-free proteins. Thus, constant production rates are deployed for producing these items even when their demands are random. In “Production Management with General Demands and Lost Sales,” Han, Li, Sethi, Siu, and Yam obtain the optimal constant production rate for a production-inventory system with Lévy demand for long-run average and expected discounted cost objectives, explicitly in some cases and numerically in general with a Fourier-cosine scheme they develop. This scheme can help in computing risk analytics of the inventory system, such as stockout probability and expected shortfall. These measures are particularly significant for assessing supply resilience, especially for emergency products or services like medicines and healthcare equipment. This study’s analytical and numerical findings contribute to enhancing efficiency and decision making in production management.

Linguistic tone in Chinese rap: an interdisciplinary approach

This study, integrating linguistics, computer science, statistics, musicology, and cultural study, explores how the lexical tones of Mandarin Chinese interact with rap music. Building upon [Dong, H. Y. (2015). Musicality meets tonality: A tonal congruence index (ITG) for Chinese vocal music. In H. Y. Tao et al. (Ed.), Proceedings of the 27th North American conference on Chinese linguistics (Vol. 2, pp. 322–339).], we develop an algorithm to compute the Tonal Congruence Index (ITG ), measuring the extent to which tones are preserved in vocal music. Analysis of a dataset with over 8000 syllables from Mandarin Chinese rap songs shows that the tonal congruence is related to subgenres that have evolved over time: while tones are largely preserved in the earlier boom-bap style, tonal distortion occurs more frequently in recent trap music. Moreover, we find that the falling fourth tone in standard Mandarin accounts for 38% of line-ending syllables in the lyrics of 140 rap songs and further suggests that the pre-eminence of the fourth tone may be a generic feature of Mandarin Chinese rap, particularly in boom bap. In addition, Chinese rappers have increasingly utilised English words over time to achieve musical flow. Integrating analytic findings with qualitative interviews of five national award-winning Chinese rappers, we conclude that the restriction of linguistic tones in Mandarin Chinese rap has gradually weakened over time and that there is a decreasing correlation between tone and rap with the emergence of new rap styles such as mumble rap and melodic rap.

Two-way communications empowered by reconfigurable intelligent surfaces and direct link: Outage analysis under hardware impairments and Nakagami-m fading

In this article, we consider a two-way communication system empowered by a reconfigurable intelligent surface (RIS), consisting of N passive reflective elements, in the presence of transceiver hardware impairments (HIs). To exploit the existence of a direct link between the end communication nodes, we utilize two time slots for their information exchange. We particularly analyze the instantaneous end-to-end signal-to-noise-plus-distortion-ratios (SNDRs) under HIs. The exact distribution of the magnitude of the end-to-end channel coefficients of the studied RIS-empowered communication system is derived under HIs and Nakagami-m fading channels. Using different settings for the level of HIs and the transmit powers at the end nodes, we also deduce novel exact and upper bound analytical expressions for the overall outage probability (OOP). For the high signal-to-noise ratio regime, an asymptotic OOP analysis is derived, which unveils the system’s diversity order. The presented numerical and simulation results corroborate our derived analytical findings, and demonstrate the impact of different system and channel parameters on the system’s OOP performance.

Out‐of‐band transaction pool sync for large dynamic blockchain networks

AbstractSynchronization of transaction pools (mempools) has shown potential for improving the performance and block propagation delay of state‐of‐the‐art blockchains. Indeed, various heuristics have been proposed in the literature to incorporate early exchanges of unconfirmed transactions into the block propagation protocol. In this work, we take a different approach, maintaining transaction synchronization externally (and independently) of the block propagation channel. In the process, we formalize the synchronization problem within a graph theoretic framework and introduce a novel algorithm (SREP—set reconciliation‐enhanced propagation) with quantifiable guarantees. We analyze the algorithm's performance for various realistic network topologies and show that it converges on static connected graphs in a time bounded by the diameter of the graph. In graphs with dynamic edges, SREP converges in an expected time that is linear in the number of nodes. We confirm our analytical findings through extensive simulations that include comparisons with MempoolSync, a recent approach from the literature. Our simulations show that SREP incurs reasonable bandwidth overhead and scales gracefully with the size of the network (unlike MempoolSync).

Clients’ first names in social work encounters: maintaining and mitigating asymmetry in institutional interaction

ABSTRACT In encounters between social workers and clients, social workers occasionally address clients by their first name, while clients more rarely use social workers’ names. In this article, we examine uses of clients’ first names in social work encounters set in public employment services. Drawing on conversation analytic findings and methods, we focus particularly on the sequential environment surrounding the use of clients’ names to discuss their role in the interaction. The article offers new contributions in two main respects: one is to the field of social work by exploring in detail how a recurrent practice such as the use of clients’ first names is involved in the production and maintenance of institutional roles and in managing power and asymmetry in the client–worker relationship. The second is that the analyses demonstrate how first name address terms are involved in performing context-specific functions in encounters between social workers and clients in a welfare-to-work setting.

Morphological characterization of Maize (Zea mays.) utilising the stage-wise structural and architectural perspective from temporal fully-polarimetric SAR

The morphological shape and structure of the crop vary with phenological stages. Model and eigen based decomposition model parameters extracted from the Radarsat-2 data and the trend with respect to ground truth crop phenology were analysed. Sensitive parameters were devised through stepwise approach under 7 combinations of polarimetric variables of increasing complexity were assessed. Compared under the three machine learning algorithms (ANN, RF and SVM) where ANN rendered the maximum correlation with 0.92 with a MAE of 4 days which was implemented on a large parcel of maize mask in the study area. SVM performed poorly with highly overlapping parameters such as backscatter but performed well (r = 0.85). For assessing the crop biophysical parameters, the three algorithms were evaluated and sensitivity analysis for statistically significant polarimetric variables for biophysical parameters was performed. The assessment was performed on Multi-Layer Perception (MLP) neural network. The networks were trained with algorithms and hidden layer nodes until the MAE achieved permissible limits. Plant height could be estimated more profoundly with an r = 0.8 with a considerably good MAE of 24.9 cm but other parameters (WB, DB and LAI) were estimated in moderate correlation of 0.6–0.65 where the MAE of WB, DB and LAI were found to be 1317gm−2, 553 gm−2 and 0.78 respectively. This is the first step towards understanding the complex scattering mechanisms in Indian maize scenario assessing the growth parameters from polarimetric data. Thus, the analytical findings brought out possess the potential to serve as the reference for the future research initiatives.

Synthetic strategies and anticancer evaluation for the novel 3-(6-heteroaryltriazolo[3,4-b][1,3,4]thiadiazol-3-yl)chromeno [2,3-b]pyridines

The novel chromonyltriazolo[3,4-b][1,3,4]thiadiazole derivative 5 was efficiently synthesized and utilized as key intermediate for construction of a diversity of heterocyclic rings; through reactions with binucleophilic reagents. Treating electron deficient substrate 5 with hydrazine hydrate, phenylhydrazine and hydroxylamine furnished pyrazolyl/isoxazolyltriazolo[3,4-b][1,3,4]thiadiazoles 6-8. Also, reacting substrate 5 with guanidine, cyanoguanidine and thiourea provided pyrimidinyltriazolo[3,4-b][1,3,4]thiadiazoles 9-11. Reaction of substrate 5 with ethylenediamine and o-phenylenediamine afforded diazepine derivatives 12 and 13. Reaction of substrate 5 with malononitrile, ethyl cyanoacetate and cyanoacetamide afforded pyrans 14, 15 and pyridine 16 linked triazolo[3,4-b][1,3,4]thiadiazolyl chromeno[2,3-b]pyridines. The anticancer efficiency of the current compounds presented diverse inhibitory action against certain cancer cell lines. On the basis of analytical and spectral findings, the structures of the synthesized products were confirmed.

Evidence of ostarine excretion in oral fluid after a single controlled oral administration

The presence of ostarine, a selective androgen receptor modulator (SARM) in an athlete’s urine specimen constitutes one of the most frequent anti-doping rules violation as the drug is listed as a member of the S1.2 class “other anabolic agents” of the World Anti-doping Agency Prohibited List, forbidden in- and out-competition. It is possible to challenge this violation but it is at the charge of the athlete to prove innocence. The conditions to evidence no fault or negligence are mostly based on 2 points: 1. the athlete must present verified circumstances of contamination and the source of contamination must be identified; and 2. there must be verified claims by the athlete that the violation was not intentional.Some months before the Olympic games, a female athlete was suspended by a national anti-doping agency because of an adverse analytical finding for ostarine. She claimed that her violation was due to drug transfer when kissing her boyfriend, who did not inform her about his ostarine daily intake. To document this claim (excretion of ostarine in oral fluid in sufficient amounts), a male volunteer ingested 17.3 mg of ostarine (dose verified by 1H NMR). Oral fluid was collected over 8 h using the NeoSal™ collection device and was tested by liquid chromatography coupled to tandem mass spectrometry. Maximal ostarine concentration was 468 ng/mL at T + 15 min, which can also be partially attributed to mouth contamination. Ostarine was detectable during the whole period of test, with concentrations at 1–2 ng/mL after T + 4 h. These results support drug transfer during kissing and subsequent possible contamination of the partner.

Far-zone analytical expressions for electromagnetic waves produced by a uniform-current loop placed in a uniaxial dielectric-magnetic material

We investigate the radiation generated by a current loop situated within an unbounded uniaxial dielectric-magnetic material characterized by a uniform current distribution. We employ dyadic Green functions in the frequency domain to derive closed-form expressions for the far-field radiation. Our analytical findings distinguish between two scenarios: one in which the loop’s axis aligns parallel to the optic axis and another where it is perpendicular to the optic axis. In cases where the loop’s axis parallel’s the optic axis, only magnetically extraordinary wave is emitted as a consequence. However, when the loop’s axis is perpendicular to the optic axis, both electrically and magnetically extraordinary waves are emitted. Our results demonstrate a pronounced dependence of the radiation pattern on the loop’s size, as observed for various loop radii.

Enhancing Network Security Through Router-Based Firewalls: An Investigation into Design, Effectiveness, and Human Factors

A firewall serves as a crucial computer program designed to block malicious software, thereby safeguarding the user's system. It helps prevent the unauthorized dissemination of personal information and the incursion of harmful viruses. Taking inspiration from China's "Great Firewall"—a sophisticated system utilizing advanced software and hardware to automatically filter, censor, and monitor internet content—this research aims to devise a router-based firewall system capable of autonomously shielding users' computers from viruses and unauthorized websites. A comprehensive questionnaire was deployed to unearth the predominant sources of information leakage among computer users and ascertain the role of firewalls within computer systems. The analytical findings underscore that the majority of information leakage security risks stem from a significant lack of personal privacy awareness and a deficient understanding of firewall security systems. The proposed firewall system harnesses router-based control to address the limitations inherent in PC software-based firmware systems. This innovation enhances the control of viral threats and the prevention of user privacy leaks. Serving as a tangible barrier, the router-based firewall obstructs the route of viruses or malevolent programs before reaching the user's computer. This strategic design substantially reduces user intervention, ensuring the continuous operation of the firewall to steadfastly protect the user's computing environment.

Body fluid contamination in the context of an adverse analytical finding in doping: About a case involving ostarine

Ostarine, also known as MK-2866 or enobosarm, is a selective androgen receptor modulator (SARM). It has anabolic properties and as such is widely used in doping, accounting in 2021 for 25 % of the adverse analytical findings (AAF) among the class S1.2 “Other anabolic agents” of products banned by the World Anti-Doping Agency, to which it belongs. But in some cases, it can be responsible for an AAF following contamination. We report the case of an athlete who contaminated herself by exchanging body fluids while kissing her boyfriend, who took 25 mg per day of MK-2866 for 9 days prior to the athlete's AAF (urinary concentration evaluated at 13 ng/mL) without her knowledge. Both subjects came to our lab for hair testing. The athlete's hair was black and slightly frizzy. Six segments of 2 cm then 7 × 3 cm (33 cm) were analysed and showed increasing concentrations, from 2 pg/mg on the first segment to 17.8 pg/mg on the last segment. The boyfriend's hair, light-brown, analyzed on 4 × 2 cm, also showed increasing values, from 65 to 143 pg/mg. These gradients of concentration in the hair’s athlete and in her boyfriend were compatible with external contamination of the hair, confirmed by analysis of washing baths, pillowcases (150 pg on each), and the athlete's hairbrush (250 pg).Fingernails were also contaminated, with 21 pg/mg in the athlete and 1041 pg/mg in the boyfriend, with highly contaminated washing baths, and toenails were less contaminated, with 2 pg/mg in the athlete and 17.3 pg/mg in the boyfriend. Urine samples taken 35 days after the start of MK-2866 treatment showed a value of 3690 ng/mL in the boyfriend and 5.7 ng/mL in the athlete. After 6 days off, these concentrations were 3.3 ng/mL and 0.1 ng/mL, respectively. A controlled transfer study was carried out 12 days after discontinuation (urine concentrations returned to negative level). After administration of 17 mg (the 25 mg/mL vial having been controlled at 17 mg/mL), urine samples were taken from the boyfriend and the athlete (n = 10 for each) for more than 25 h after they had been living normally with each other (regular kissing in particular). The boyfriend's urine concentrations ranged from 681 ng/mL to 12822 ng/mL (Tmax = 8:30 hrs), and the athlete's from 0.3 ng/mL to 13 ng/mL with Tmax = 8:30 hrs, i.e. at 22:30 hrs, which corresponded exactly to the time of collection of the urine that showed AAF, with a similar concentration. The dose ingested by the athlete was estimated at 15 µg. These results demonstrate the transfer of ostarine via body fluids between two subjects, with a high risk of AAF in one athlete, as observed in our case.

Sorption Efficacy of Weathered Basalt Rock for Metal Ions of Nuclear Importance

Background:: A safe and long-term isolation of radionuclides is crucial for efficient waste management in the nuclear fuel cycle. Clay minerals of geological origin are considered candidate barrier materials for the sequestration of nuclear waste for geological disposal applications. Objective:: The present study encompasses a systematic characterization of weathered basalt rock and the influence of its constituent clay minerals (formed mainly due to the weathering process) in the uptake of metal ions of nuclear importance, such as cesium (Cs+) and strontium (Sr2+). Method:: The structural profile of the weathered basalt has been investigated using different analytical techniques, including polarizing microscope, XRD, FTIR and EDXRF. The sorption behaviour of the rock sample for Cs+ and Sr2+ has been investigated in a comprehensive batch mode by varying the experimental conditions. The analytical findings for structure and batch sorption performance of the material have been further correlated to understand the influence of different parameters on the uptake of metal ions and the underlying mechanism. Results:: Structural analyses confirmed the presence of clay minerals viz., kaolinite, illite and montmorillonite in the sample. A comprehensive sorption performance assessment carried out in batch mode at different experimental conditions revealed that the uptake of both the metal ions was rapid and dependent on initial metal ion concentration and solution pH. The uptake of Cs+ ions was found to be higher as compared to the Sr2+ ions. EDXRF analysis confirmed the loading of Cs+ and Sr2+ on the weathered basalt. Experimental batch sorption data presented a better agreement with the theoretical Freundlich isotherm pertaining to the heterogeneous nature of the sorbent. Conclusion:: The studies highlight that the clay minerals formed by structural alteration of basalt rock upon intense weathering could be very useful in fixing the nuclear fission waste components such as Cs+ and Sr2+.