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Stochastic dynamics and probability analysis for a generalized epidemic model with environmental noise
No full textIn this paper we consider a stochastic SEIQR (Susceptible–Exposed–Infected–Quarantined–Recovered) epidemic model with a generalized incidence function. Using the Lyapunov method, we establish the existence and uniqueness of a global positive solution to the model, ensuring that it remains well-defined over time. We further establish V-geometric ergodicity, which guarantees the exponential convergence of the system's probability distribution to its stationary measure, providing a quantitative measure of the system's stability over time. By leveraging Young's and Chebyshev's inequalities, we demonstrate the concepts of stochastic ultimate boundedness and stochastic permanence, providing insights into the long-term behavior of the epidemic dynamics under random perturbations. Additionally, we derive conditions for stochastic extinction, which describes scenarios where the epidemic may eventually die out. Finally, we perform numerical simulations to verify our theoretical results and assess the model's behavior under different parameters
Power law behavior of center-like decaying oscillation: Exponent through Perturbation Theory and Optimization
No full textIn dynamical systems theory, there is a lack of a straightforward rule to distinguish exact center solutions from decaying center-like solutions, as both require the damping force function to be zero (Sarkar et al., 2011; Saha and Gangopadhyay, 2018). By adopting a multi-scale perturbative method, we have demonstrated a general rule for the decaying center-like power law behavior, characterized by an exponent of [Formula presented]. The investigation began with a physical question about the higher-order nonlinearity in a damping force function, which exhibits birhythmic and trirhythmic behavior under a transition to a decaying center-type solution. Using numerical optimization algorithms, we identified the power law exponent for decaying center-type behavior across various rhythmic conditions. For all scenarios, we consistently observed a decaying power law with an exponent of [Formula presented]. Our study aims to elucidate their dynamical differences, contributing to theoretical insights and practical applications where distinguishing between different types of center-like behavior is crucial. This key result would be beneficial for studying the multi-rhythmic nature of biological and engineering systems.SS acknowledges Prof. Gautam Gangopadhyay (SNBNCBS Kolkata), Prof. Deb Shankar Ray (IACS Kolkata), Prof. Jesper. N. Tegnér (KAUST, KSA), Dr. Debasish Mondal (IIT Tirupati), Dr. Pushpita Ghosh (IISER TVM), Prof. Sandip Kar (IIT Bombay), Dr. Somrita Ray (IISER BBSR), Dr. Subhadip Chakraborti (FAU Germany), Prof. Sagar Chakraborty (IIT Kanpur) and Dr. Ankan Pandey for their valuable support and insightful discussions. SS would also like to thank ChatGPT for assisting with language improvements and editing suggestions
Design and Process Development of Graphene-Based Geometric Diodes for Enhanced Performance
No full textGraphene geometric diodes (GGDs) are innovative nanoscale devices that utilize asymmetric structural designs and ballistic transport mechanism to enable rectification without relying on traditional semiconductor junctions. This unique approach allows for directional charge transport, resulting in high-speed and broadband operation, offering promising potential for applications in energy harvesting, terahertz (THz) detection, and high-speed logic circuits. Despite their promise, the field faces significant challenges, including limitations in scalable fabrication, difficulties in achieving improved asymmetry ratios for enhanced performance, and lack of effective geometry design strategies. In addition, graphene's unique properties (particularly its electrical tunability) have not been fully explored in the previous works. This thesis tackles these challenges by advancing the understanding of GGDs and presenting innovative solutions through advanced nanofabrication approaches and computational methodologies, including artificial intelligence (AI).
The first issue of device scalability is studied in the first work of this thesis. Previous research on GGDs primarily relied on exfoliated graphene to achieve high mobility but was constrained by its limited size. In contrast, this study explores the use of chemical vapor deposition (CVD)-grown monolayer graphene, which, despite its lower mobility making ballistic transport more challenging to achieve, offers greater suitability for mass production. These advancements enable scalable production of GGDs and establish a definitive correlation between device performance and neck width.
The second challenge in enhancing device performance arises from the need for graphene with extremely high mobility and the requirement for ultra-small geometric feature sizes. To address this, this work integrates high-quality h-BN/Graphene/h-BN heterojunctions with advanced high-resolution electron beam lithography, achieving significant improvements in device performance. Additionally, this work also studies device gate-tunable functionalities that enable multi-state rectification. This innovation expands the operational versatility of GGDs and demonstrates their suitability for advanced electronic applications.
Finally, this thesis addresses the bottleneck in GGD design optimization due to the extensive simulation and time-intensive fabrication process required for such devices, by integrating deep learning methodologies with drift-diffusion simulations. The developed framework rapidly identifies a novel enhanced device geometry, achieving record-breaking asymmetry ratios while reducing fabrication iterations and aligning experimental results with theoretical predictions.
By integrating innovative methodologies, this thesis enhances the understanding and optimization of GGDs, establishing a solid foundation for their development and offering valuable guidance for future advancements in the field
Functional Time Series Analysis and Visualization Based on Records
No full textThis research was supported by the King Abdullah University of Science and Technology (KAUST). The authors thank the King Abdullah City for Atomic and Renewable Energy (K.A. CARE) for providing the wind speed observational data. Also, the authors thank the associate editor and the referees for their thoughtful and constructive comments and suggestions
The Triple-C Paradigm: Cooperative, Complementary, and Competitive Modes for TBS-HAPS-LEO Integration
No full textThe growing demands of ubiquitous and resilient global coverage have pushed existing networks to their operational limits, making it increasingly difficult to meet all requirements on their own. Integrating \emph{Terrestrial Base Stations (TBS), High Altitude Platform Stations (HAPS)} and \emph{Low-Earth-Orbit (LEO)} satellites is envisioned as a promising solution, yet the coordination across these heterogeneous platforms remains an open challenge. This paper proposes a novel unifying \emph{Triple-C framework: Cooperation, Complementarity, and Competition}, that systematically defines the TBS-HAPS-LEO interaction to deliver seamless resilient and scalable connectivity. For each C, we detail the architectural methodology, required pre-requisites, and measurable deliverables that govern when and how the three layers should collaborate, complement each other, or contend. We further identify the enabling technologies across physical, logical, and cognitive layers to operationalize the proposed 3C paradigm. A rich portfolio of use cases and targeted applications demonstrates how this technological leap will make such integration both feasible and impactful. Comprehensive performance analysis and emulation results quantify the trade-offs of such integrated networks. In addition, we examine the economical, environmental, safety, privacy, standardization, and regulatory implications that shape the real-world implementation of the proposed framework. eventually, we provide the gap analysis, outline key technical/non-technical challenges, and a road-map of future research directions needed to unlock the full potential of Cooperation, Complementarity, and Competition operations in TBS-HAPS-LEO integrated networks.We would like to express our gratitude to AI(ChatGPT) for its invaluable assistance in refining the grammar, enhancing clarity, and rephrasing sentences, particularly in the introduction section. While ChatGPT has contributed to enhancing the linguistic quality of our work, it’s important to note that the core concepts, construction of the 3C paradigm, supporting arguments, and performance analysis were achieved independently, without the assistance of AI
Role of Phosphorus on ZSM-5 Zeolite for the Methanol-to-Hydrocarbon Reaction
No full textPhosphorus modification is a widely adopted strategy for modulating the performance of ZSM-5 catalysts in methanol-to-hydrocarbon (MTH) reactions. However, the underlying modification mechanism for the structure–performance relationship is not yet fully understood. In this study, a series of phosphorus-modified ZSM-5 (P-ZSM-5) catalysts were synthesized via direct impregnation using ammonium phosphate dibasic as the phosphorus source. With this synthetic method, the aluminum content and structural properties of zeolite are preserved. Our findings showed that phosphorus loading significantly alters the acidity and microporous properties of ZSM-5. To explore the underlying reasons for these changes, we employed 31P and 27Al solid-state magic angle spining (MAS) nuclear magnetic resonance (NMR), which provided chemical and structural insights. The lower amount of strong acid sites resulted in a prolonged lifetime in the MTH reaction and enhanced selectivity toward alkenes for P-ZSM-5. Additionally, the pore narrowing created by adding phosphorus had an additional effect on product selectivity by suppressing o-xylene yields. By using the 13C, 13C–13C, and 1H–13C MAS NMR analysis conducted on the 13C-methanol-reacted catalysts, we demonstrated direct evidence that P-ZSM-5 preserved the same MTH pathways but suppressed the formation of one of the key coke precursors, the 1,2,3-trimethylcyclopentenyl cation. This was further confirmed by the operando UV–vis results, along with the reduced accumulation rate of other coke precursors such as naphthalene and polyaromatics.The authors are grateful for the funding support from King Abdullah University of Science and Technology, Competitive Research Grant URF/1/5083-01-01. This work was also supported by the Soonchunhyang University Research Fund. We especially thank Dr. Edy Abou–Hamad and Dr. Chris Canlas for technical support for solid-state NMR spectroscopy; Polina Lavrik for transmission electron microscopy analysis; Cristina Queiros Da Silva for supporting NH3-TPD analysis and technical support; Eganathan Kaliyamoorthy for ICP–OES; Marina Chernova, Jurjen Cazemier, and Teng Li for the technical support and silicalite-1 offering; and Sohrab Askarli for scientific discussion
Early and Sustained Shift in Headache Day Frequency Following Eptinezumab Treatment in Adults With Migraine for Whom 2–4 Previous Preventive Treatments Have Failed: A Post Hoc Analysis of the Randomized <scp>DELIVER</scp> Trial
No full textABSTRACT
Background
This post hoc analysis examined the reduction in monthly headache days (MHDs) by frequency category shifts and associated improvements following eptinezumab treatment.
Methods
The DELIVER trial evaluated eptinezumab in adults with migraine for whom 2–4 previous preventive treatments failed. During a 24-week, double-blind, placebo-controlled period followed by a 48-week extension period, participants received IV eptinezumab 100 mg, 300 mg, or placebo every 12 weeks, with all receiving eptinezumab beginning Week 25 (dose-blinded). Participants were categorized by MHD frequency: > 14, 8–14, 4 to 14 baseline MHDs and early ≥ 50% responders). In participants reporting < 8 MHDs after all doses, the associated changes in headache intensity and disease status were evaluated.
Results
Of randomized participants, 88% (782/890) completed the trial. The percentage of participants randomized initially to eptinezumab who reported 14 to < 8 MHDs, 66% (49/74) reported < 8 MHDs for the rest of the trial. Reduction to < 8 MHDs was associated with robust improvements in headache intensity and disease burden.
Conclusions
Eptinezumab was associated with sustained reduction in MHD category, with some achieving headache/migraine freedom in patients with a history of preventive treatments that failed.Medical writing and manuscript preparation support was funded by
H. Lundbeck A/S and provided by Mary Tom, PhD, Nicole Coolbaugh,
CMPP, and Brittany Friedson, PhD, of The Medicine Group LLC
(New Hope, PA, USA) in accordance with Good Publication Practice
guidelines.
The trial and medical writing support were sponsored and funded by H.
Lundbeck A/S. In collaboration with the academic authors, the sponsor
participated in the design and conduct of the trial and in the collection,
management, analysis, and interpretation of the data. The preparation,
review, and approval of the manuscript were undertaken by all authors
and by a professional medical writer and editor funded by the sponsor.
All authors and H. Lundbeck A/S prepared, reviewed, and approved
the final version of the manuscript and made the decision to submit the
manuscript for publication
Interannual variations of mixed layer temperature and salinity in the South Indian Ocean salinity maxima region
No full textThe study explores mixed layer temperature (MLT) and salinity (MLS) variability in the salinity maxima region present in the South Indian Ocean (SIO) on interannual time scale using ECCOv4r4 and Argo observations. It is observed that MLT and MLS are in tandem with surface heat flux and evaporation changes during the austral summer and winter seasons. Although the monthly evolution of high salinity in the SIO shows that the high salinity core is primarily located near 30° S, with notable seasonal variability south of 30° S. The region exhibits high interannual variability in MLT compared to MLS. Covariance and budget analysis show that net heat flux is the primary and significant component that contributes to the mixed-layer heat budget. However, changes in MLS are mainly attributed to meridional advection and entrainment. Furthermore, MLT variability is separated into two phases (I) 1992−2006, where the temperature is mostly below climatological value and (II) after 2007, the temperature is seen increasing with a hiatus-like signature from 2010−2015. During phase I, the MLT tendency is driven by meridional advection followed by net heat flux. However, in phase II, net heat flux mainly drives the temperature tendency, and meridional advection plays a secondary role. Whereas, salinity tendency is mainly driven by meridional advection. Further, in 1992−2006 period, downward Ekman pumping results from the strengthening of wind stress curl, led to the deepening of the mixed layer, while after 2006 MLD shoals due to weakening of wind stress curl. Additionally, during the second phase, the reduced meridional velocities in the mixed layer contribute to warming and salinification in the region.This work has been carried out at Indian Institute of Technology Kharagpur, India. Authors would like to thank Institute for providing all needed support to carry out this research. We would like to thank the anonymous reviewers for their comments and suggestions which helped to improve the manuscript significantly. Madhu Kaundal thanks Ministry of Education, Government of India for the research fellowship. All the analysis and plotting are done in python using packages numpy, xarray, and matplotlib
Molecular Structure and Thermodynamics of CO<sub>2</sub> and Water Adsorption on Mica
No full textThe adsorption of CO2 and water on clay surfaces plays a key role in applications, such as gas storage in saline aquifers and depleted hydrocarbon reservoirs, but is not yet fully understood. Here, we study the adsorption of CO2 and water vapor using Grand Canonical Monte Carlo and molecular dynamics simulations. At a bulk pressure of 100 bar, pure CO2 adsorbs strongly on mica and forms extensive layers next to it. CO2 adsorption is lowered substantially if introducing water vapor above mica and is largely eliminated when the relative humidity (RH) approaches about 60%. When pure water vapor is introduced above a mica surface, a subnanometer thick liquid water film develops on it to form apparent liquid-solid and liquid-vapor interfaces simultaneously. Using the identification of truly interfacial molecules (ITIM) analysis, we delineate how individual water layers develop in this film as RH increases. We highlight that the water film is spatially heterogeneous and the true liquid-vapor interface emerges only at an RH of 60-80%. Introducing 100 bar of CO2 into the water vapor above the mica surface modulates water adsorption nonlinearly: at RH = 0.01%, the water adsorption is reduced by ∼30%; as RH increases, the reduction is weakened, and eventually, enhancement of water adsorption by about 7% occurs at RH = 90%. These variations are attributed to the interplay of film thinning by high-pressure CO2, competition of mica surface sites by CO2 molecules, and energetic and entropic stabilization of interfacial water by CO2 molecules.This article has been authored by UT-Battelle, LLC, under Contract DE-AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). Acknowledgment
Towards decarbonized heavy-duty road transportation: Design and carbon footprint of adsorption-based carbon capture technologies using life cycle thinking
No full textRoad transportation is a necessity for global economic activities because it not only moves goods but also connects people. On the contrary, it contributes significantly to climate change. The rising demand for heavy-duty transportation, coupled with increasing global warming concerns, has necessitated solutions for decarbonization. The transition to zero-emissions is challenging due to factors such as high energy–density demand, high reliability, and the need to travel long distances, which stem from fossil fuel combustion. This study designs a carbon capture and storage adsorption-based system to mitigate CO2 emissions from heavy-duty vehicles. The method integrates three classes of adsorbent materials, including metal–organic frameworks (MOFs), zeolites, and solid amines for capture and Cr-soc-MOF for storage. The study calculates the size, CO2 purity and recovery, and power demand of the system. Further, it quantifies the effective global warming potential reduction based on a comparative life cycle assessment study. The results of the study show the feasibility of decarbonization of heavy-duty vehicles through onboard carbon capture and storage.The authors acknowledge funding provided by King Abdullah University of Science and Technology and the Clean Energy Research Platform