Search for: All records

Abstract BackgroundSince the 1980s, Pacific Black Brant (Branta bernicla nigricans, hereafter brant) have shifted their winter distribution northward from Mexico to Alaska (approximately 4500 km) with changes in climate. Alongside this shift, the primary breeding population of brant has declined. To understand the population-level implications of the changing migration strategy of brant, it is important to connect movement and demographic data. Our objectives were to calculate migratory connectivity, a measure of spatial and temporal overlap during the non-breeding period, for Arctic and subarctic breeding populations of brant, and to determine if variation in migration strategies affected nesting phenology and nest survival. MethodsWe derived a migratory network using light-level geolocator migration tracks from an Arctic site (Colville River Delta) and a subarctic site (Tutakoke River) in Alaska. Using this network, we quantified the migratory connectivity of the two populations during the winter. We also compared nest success rates among brant that used different combinations of winter sites and breeding sites. ResultsThe two breeding populations were well mixed during the winter, as indicated by a migratory connectivity score close to 0 (− 0.06) at the primary wintering sites of Izembek Lagoon, Alaska (n = 11 brant) and Baja California, Mexico (n = 48). However, Arctic birds were more likely to migrate the shorter distance to Izembek (transition probability = 0.24) compared to subarctic birds (transition probability = 0.09). Nest survival for both breeding populations was relatively high (0.88–0.92), and we did not detect an effect of wintering site on nest success the following year. ConclusionsNest survival of brant did not differ among brant that used wintering sites despite a 4500 km difference in migration distances. Our results also suggested that the growing Arctic breeding population is unlikely to compensate for declines in the larger breeding population of brant in the subarctic. However, this study took place in 2011–2014 and wintering at Izembek Lagoon may have greater implications for reproductive success under future climate conditions. 

The growing adoption of intelligent Electric Vehicles (EVs) has also created an opportunity for malicious actors to initiate attacks on the EV infrastructure, which can include a number of data exchange protocols across the various entities that are part of the EV charging ecosystem. These protocols possess a range of underlying vulnerabilities that attackers can exploit to disrupt the regular flow of information and energy. While researchers have considered vulnerabilities of particular components within an EV charging ecosystem, there is still a notable gap in vulnerability analysis of charging protocols and the potential threats to these. We investigate threat vectors within the most widely adopted protocols used in EV infrastructure, explore the potential impact of cyberattacks and suggest various mitigation techniques investigated in literature. Potential future research directions are also identified. 

Abstract We construct a quantum Frobenius map for the $$SL_{3}$$ skein module of any oriented 3-manifold specialized at a root of unity, and describe the map by way of threading certain polynomials along links. The homomorphism is a higher rank version of the Chebyshev–Frobenius homomorphism of Bonahon–Wong. The strategy builds on a previous construction of the Frobenius map for $$SL_{3}$$ skein algebras of punctured surfaces, using the Frobenius map of Parshall–Wang for the quantum group $$\mathcal{O}_{q}(SL_{3}).$$ 

This study presents a comprehensive analysis of the etching effects on β-Ga2O3 using two methods: H2_N2 (a mixture of hydrogen and nitrogen) etching and triethylgallium (TEGa) in situ etching performed in a metal-organic chemical vapor deposition system. By employing a mix of H2 and N2 gases at varying chamber pressures and maintaining a constant etching temperature of 750 °C, we investigated the etching dynamics across three different β-Ga2O3 orientations: (010), (001), and (2¯01). Field emission scanning electron microscopy analysis showed that the etching behavior of β-Ga2O3 depends on the crystal orientation, with the (010) orientation showing notably uniform and smooth surfaces, indicating its suitability for vertical device applications. High-aspect-ratio β-Ga2O3 fin arrays were fabricated on (010) substrates using H2_N2 etching, yielding fin structures with widths of 2 μm and depths of 3.1 μm, along with smooth and well-defined sidewalls. The etching process achieved exceptionally high etch rates (>18 μm/h) with a strong dependence on pressure and sidewall orientation, revealing the trade-off between etch depth and surface smoothness. Separately, TEGa in situ etching was investigated as an alternative etching technique for both β-Ga2O3 and β-(AlxGa1−x)2O3 films. The results revealed that the (010) orientation exhibited relatively high etching rates while maintaining smoother sidewalls and top surfaces, making it favorable for device processing. In contrast, the (001) orientation showed strong resistance to TEGa etching. Furthermore, Al-incorporated β-(AlxGa1−x)2O3 films showed substantially lower etch rates compared to pure β-Ga2O3, suggesting their potential use as an effective etch-stop layer in advanced device fabrication. 

Integer-order calculus fails to capture the long-range dependence (LRD) and memory effects found in many complex systems. Fractional calculus addresses these gaps through fractional-order integrals and derivatives, but fractional-order dynamical systems pose substantial challenges in system identification and optimal control tasks. In this paper, we theoretically derive the optimal control via linear quadratic regulator (LQR) for fractional-order linear time-invariant (FOLTI) systems and develop an end-to-end deep learning framework based on this theoretical foundation. Our approach establishes a rigorous mathematical model, derives analytical solutions, and incorporates deep learning to achieve data-driven optimal control of FOLTI systems. Our key contributions include: (i) proposing a novel method for system identification and optimal control strategy in FOLTI systems, (ii) developing the first end-to-end data-driven learning framework, Fractional-Order Learning for Optimal Control (FOLOC), that learns control policies from observed trajectories, and (iii) deriving theoretical bounds on the sample complexity for learning accurate control policies under fractional-order dynamics. Experimental results indicate that our method accurately approximates fractional-order system behaviors without relying on Gaussian noise assumptions, pointing to promising avenues for advanced optimal control. 

In 1979, Hylland and Zeckhauser [26] gave a simple and general mechanism for a 6 one-sided matching market, given cardinal utilities of agents over goods. They use the power of a 7 pricing mechanism, which endows their mechanism with several desirable properties – it produces an 8 allocation that is Pareto optimal and envy-free, and the mechanism is incentive compatible in the 9 large. It therefore provides an attractive, off-the-shelf method for running an application involving 10 such a market. With matching markets becoming ever more prevalent and impactful, it is imperative 11 to characterize the computational complexity of this mechanism. 12 We present the following results: 13 1. A combinatorial, strongly polynomial time algorithm for the dichotomous case, i.e., 0/1 14 utilities, and more generally, when each agent’s utilities come from a bi-valued set. 15 2. An example that has only irrational equilibria; hence this problem is not in PPAD. 16 3. A proof of membership of the problem in the class FIXP; as a corollary we get that an 17 HZ equilibrium can always be expressed via algebraic numbers. For this purpose, we give 18 a new proof of the existence of an HZ equilibrium using Brouwer’s fixed point theorem; 19 the proof of Hylland and Zeckhauser used Kakutani’s fixed point theorem, which is more 20 involved. 21 4. A proof of membership of the problem of computing an approximate HZ equilibrium in the 22 class PPAD. 

ABSTRACT Given a reversible Markov chain on states, and another chain obtained by perturbing each row of by at most in total variation, we study the total variation distance between the two stationary distributions, . We show that for chains withcutoff, converges to 0, is asymptotically at most (with a sequence of perturbations for which convergence to this bound occurs), and converges to 1, respectively, if the product of and the mixing time of converges to 0, , and , respectively. This echoes recent results for specific random walks that exhibit cutoff, suggesting that cutoff is the key property underlying such results. Moreover, we show is maximized byrestart perturbations, for which “restarts” at a random state with probability at each step. Finally, we show thatpre‐cutoffis (almost) equivalent to a notion of “sensitivity to restart perturbations,” suggesting that chains with sharper convergence to stationarity are inherently less robust.