Understanding the emergence of tipping points is essential for safeguarding populations and maintaining ecosystem stability. This study investigates the influence of environmental stochasticity on tipping phenomena within a planktonic system. Plankton populations in aquatic ecosystems are highly sensitive to environmental fluctuations, driven by factors such as the bioavailability of essential nutrients, acid content, and aquatic thermal conditions. To explore these dynamics, we formulate and analyze a two-dimensional stochastic model involving toxin-producing phytoplankton and zooplankton. In the absence of noise, the deterministic system exhibits a rich array of bifurcations, including saddle-node, transcritical, Hopf, and BT bifurcations. A persistence and extinction analysis is conducted to assess species viability under varying ecological conditions. Bistability emerges between coexistence states and a zooplankton-free equilibrium, governed by toxin liberation rates. Furthermore, we identify three distinct types of noise-induced tipping: transitions between two coexistence states and shifts between coexistence and zooplankton extinction states. Our results underscore the critical role of initial species abundance in triggering these tipping events. To quantify the likelihood of state switching, we construct confidence ellipses and estimate threshold noise intensities using numerical simulations informed by stochastic sensitivity analysis. Overall, this study offers novel insights into the mechanisms underlying ecological tipping points and provides a foundation for identifying potential control strategies within the framework of plankton ecology.
In this research work, the authors have developed a highly efficient optical switch based on exotic GaN/Al0.45Ga0.55N/GaN/GaN p+-n-n−-n+ High Electron Mobility Avalanche Photodiode (HEM-APD) in 200 nm to 500 nm wavelength. The optical characteristics of a designed optical switch are analysed by developing a Quantum Modified Carrier Transport Model (QMCTM) coupled with the Monte Carlo simulation technique in terms of absorption coefficient, extinction coefficient, transmission, and reflection spectrum, gain and excess noise factor. Due to the incorporation of a small mole fraction of Al into the GAN, the 2-D Electron Gas (2-DEG) is formed at the interface between the GaN and AlGaN. The 2-DEG significantly enhances electron mobility in the active region of the device at low temperatures. Hence, the electron can travel quickly without restraint through the active region of the device. This phenomenon leads to quicker operation of the device. Additionally, the performance of the designed HEM-APD based optical switch is compared with its flat AlGaN/GaN counterpart. It is observed that the performance of the designed HEM-APD based optical switch is significantly higher compared to its counterpart. The authors have also validated the developed Quantum Modified Carrier Transport Model (QMCTM) coupled with the Monte Carlo simulation technique through experimental verification. This is the first report on development of highly efficient optical switch based on an exotic GaN/Al0.45Ga0.55N/GaN/GaN type p+-n-n–n+ High Electron Mobility Avalanche Photodiode (HEM-APD) in 200 nm to 500 nm wavelength.
Lung cancer accounts for the highest number of deaths due to cancer in the world. Precise and prompt identification on the basis of histopathology pictures is vital in enhancing survival outcomes. This study proposes to create a fast and intelligible CNN with high accuracy and an easy-to-use CBQA model that can be deployed in the clinical setting. To do this, we created a bespoke model of CNN with four convolutional layers, group normalisation, dropout and SoftMax output. A small balanced dataset of 15,000 histopathology images (5000 adenocarcinoma, 5000 squamous cell carcinoma, 5000 benign) out of Kaggle dataset of Lung Cancer Histopathological Images was adopted with a 70–15–15
BACKGROUND:Neurovascular electronic devices, including brain-computer interfaces (BCIs), offer a minimally invasive approach to diagnosing and treating neurological disorders. Implanting BCIs in superficial cortical veins, owing to their proximity to sensorimotor cortices, may improve motor function restoration. However, marked anatomical variability and the complex anteriorly directed connection with the superior sagittal sinus (SSS) complicate device navigation. This exploratory study aimed to characterize cortical venous anatomy to inform device design and procedural planning. METHODS:Retrospective imaging data from 25 patients were analyzed using magnetic resonance venography (MRV) and computed tomography venography (CTV). Vessel segmentation and analysis quantified parameters such as vein presence, diameter, length, angulation, and tortuosity. In 12 patients, T1-weighted magnetic resonance imaging (MRI) was used to extract cortical gyri and sulci, assessing vessel-cortex relationships. RESULTS:The superior anastomotic vein (vein of Trolard) was identified bilaterally in 84% of patients, with a mean entrance diameter of 4.4 mm. Frequent transient constrictions (<2 mm) were reported. The precentral vein was present bilaterally in 52% of cases. Most cortical veins exhibited take-off angles >90 degrees from the SSS, presenting challenges for endovascular navigation, with overall considerable anatomical variability observed. CONCLUSION:The vein of Trolard shows promise as a target for endovascular BCIs given its consistent presence and favorable dimensions. Nonetheless, constrictions and steep angulation at the SSS confluence pose challenges for device deployment. A new framework is necessary for the classification of cortical venous anatomy, to guide patient selection and procedural planning, which will require further development and validation.
This paper presents a new single-switch flyback converter with passive leakage recovery snubber comprising of three diodes, a clamp capacitor, and a small transformer, rated only 5
