This paper studies the conjecture of Hirschfeldt, Miller, and Podzorov in [13] on the complexity of order-computable sets, where a set A is order-computable if there is a computable copy of the structure $(\mathbb {N}, <,A)$ in the language of linear orders together with a unary predicate. The class of order-computable sets forms a subclass of $\Delta ^{0}_{2}$ sets. Firstly, we study the complexity of computably enumerable (c.e.) order-computable sets and prove that the index set of c.e. order-computable sets is $\Sigma ^{0}_{4}$-complete. Secondly, as a corollary of the main result on c.e. order-computable sets, we obtain that the index set of general order computable sets is $\Sigma ^{0}_{4}$-complete within the index set of $\Delta ^{0}_{2}$ sets. Finally, we continue to study the complexity of more general $\Delta ^{0}_{2}$ sets and prove that the index set of $\Delta ^{0}_{2}$ sets is $\Pi ^{0}_{3}$-complete.

Let $G$ be a group. The notion of linear sofic approximations of $G$ over an arbitrary field $F$ was introduced and systematically studied by Arzhantseva and Păunescu [3]. Inspired by one of the results of [3], we introduce and study the invariant $\kappa _F(G)$ that captures the quality of linear sofic approximations of $G$ over $F$. In this work, we show that when $F$ has characteristic zero and $G$ is linear sofic over $F$, then $\kappa _F(G)$ takes values in the interval $[1/2,1]$ and $1/2$ cannot be replaced by any larger value. Further, we show that under the same conditions, $\kappa _F(G)=1$ when $G$ is torsion-free. These results answer a question posed by Arzhantseva and Păunescu [3] for fields of characteristic zero. One of the new ingredients of our proofs is an effective non-concentration estimates for random walks on finitely generated abelian groups, which may be of independent interest.

The dynamic behaviour of helicopter during water impact, considering variations in initial downward velocity and pitching angle, have been investigated numerically and theoretically in the present study. The air-water two-phase flows are simulated by solving unsteady Reynolds-averaged Navier-Stokes equations enclosed by standard $k - \omega $ turbulence model. A treatment for computational domain in combination with a global dynamic mesh technique is applied to deal with the relative motion between the helicopter and water. Results indicate that the initial downward velocity of helicopter exhibits behaviour similar to that of a V-shaped body impacting on water, as does the initial pitching angle. To extend the theoretical approach for predicting the kinematic parameters during helicopter ditching, a shape factor capturing the combined effect of various attributes and an average deadrise angle for asymmetric wedges are also introduced.

The stratigraphic record of the Early Holocene in the Nebraska Sand Hills suggests dry climatic conditions and periods of sustained aeolian activity, which resulted in several well-documented instances of sand dunes blocking river drainages in the western Sand Hills. Here, we present evidence that drainage blockage by migrating sand dunes also occurred in the central Sand Hills, where precipitation is higher and dune morphology differs. The South Fork Dismal River valley contains a sequence of aeolian, alluvial, and lacustrine sediments that record a gradual rise of the local water table following a sand dune blockage of the river valley around 11,000 years ago. After the initial development of a wetland, a lake formed and persisted for at least 2000 years. Increased groundwater discharge due to a warm, moist climate in the region after 6500 years ago likely caused the breaching of the dune dam and eventually resulted in the decline of the local water table. Through a careful examination of the intricate relationships between ground water, surface water, and sand movement in a dune field setting, we discuss the hydrologic system's complex response to climate change. We use diatoms to reconstruct the lacustrine environment and optically stimulated luminescence and radiocarbon dating to provide chronological control, based on a careful evaluation of the strengths and limitations of each method in varied depositional environments.

Studies of colonialism often associate indirect colonial rule with continuity of the precolonial institutions. Yet, we know less about how colonialism affected the distribution of power between precolonial domestic elites within nominally continuous institutions. We argue that colonial authorities will redistribute power toward elites that are the most congruent with the colonizer’s objectives. We test our theory on the British occupation of Egypt in 1882. Using an original dataset on members of the Egyptian parliament and a difference-in-differences empirical strategy, we show that the colonial authorities shifted parliamentary representation toward the (congruent) landed elite and away from the (oppositional) rural middle class. This shift was greater in cotton-producing provinces which were more exposed to colonial economic interest. Our results demonstrate that the colonial redistribution of power within precolonial institutions can reengineer the social-structural fabric of colonized societies.

Actuator faults in unmanned aerial vehicles (UAVs) can have significant and potentially adverse effects on their safety and performance, highlighting the critical importance of fault diagnosis in UAV design. Ensuring the reliability of these systems in various applications often requires the use of advanced diagnostic algorithms. Artificial intelligence methods, such as deep learning and machine learning techniques, enable fault diagnosis through sample-based learning without the need for prior knowledge of fault mechanisms or physics-based models. However, UAV fault datasets are typically small due to stringent safety standards, which presents challenges for achieving high-performance fault diagnosis. To address this, deep reinforcement learning (DRL) algorithms offer a unique advantage by combining deep learning’s automatic feature extraction with reinforcement learning’s interactive learning approach, improving both learning capabilities and robustness. In this study, we propose and evaluate two DRL-based fault diagnosis models, which demonstrate remarkable accuracy in fault diagnosis, consistently exceeding $99{\rm{\% }}$. Notably, under small sample scenarios, the proposed models significantly outperform traditional classifiers such as decision trees, support vector machines, and multilayer perceptron neural networks. These findings suggest that the integration of DRL enhances fault diagnosis performance, particularly in data-limited environments.

Obruchevodid petalodonts are rare small chondrichthyans known from nearly complete to partial skeletons from the Upper Mississippian (Serpukhovian) Bear Gulch Limestone of central Montana and isolated teeth from the Upper Mississippian Bangor Limestone of northern Alabama. New records of obruchevodid petalodonts are presented here from the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky. Obruchevodids are here represented by multiple teeth of a new taxon, Clavusodens mcginnisi n. gen. n. sp., and a single tooth referred to ?Netsepoye sp. Clavusodens mcginnisi n. gen. n. sp. is characterized by teeth with pointed mesiodistal and lingual margins and more robust chisel-like cusps on the anterolateral and distolateral teeth. The suggestion that obruchevodid petalodonts evolved to inhabit complex reef-like environments and other nearshore habitats with a feeding ecology analogous to extant triggerfish is explored and discussed.

UUID: http://zoobank.org/0955c37a-c458-4a4d-89c4-01d6915adeca

We propose a consumption-based model to explain puzzling unstable (i.e., sometimes positive and sometimes negative) relations between stock market variance with both stock market risk premia and prices. In the model, market risk premia depend positively (negatively) on fear (euphoria) variance. Market prices, which decrease with discount rates, correlate negatively (positively) with fear (euphoria) variance. Because it is the sum of fear and euphoria variances, the market variance may correlate positively or negatively with expected returns and prices, depending on the relative importance of the two variances. Our empirical results support the model’s key assumptions and many novel implications.

Looking at Canadian provincial pediatric health care policies and laws, the best interest standard (BIS) enjoys support. Within philosophy, however, the BIS faces serious opposition. Granted, there remain a few fervent defenders of the BIS in the contemporary literature; however, I argue that while some authors nominally defend the BIS, my analysis reveals that what they really defend is at best a watered down version of it. In this article, I argue that not only must the BIS be understood narrowly, but a substitute decision-maker (SDM) must satisfy the BIS — for an SDM is her patient's fiduciary.

The excavation of a stratified sequence of deposits spanning the Initial Late Formative period (250 BC–AD 120) at Iruhito, in the upper Desaguadero Valley of Bolivia, provides insight into this previously unrecognized, four-century period separating the well-documented Middle Formative (800–250 BC) from the Late Formative (~AD 120–590) period. By tracking subtle shifts in ceramic, architectural, lithic, and faunal data, we can explore tempos of change in social life during this dynamic time. These data lead us to suggest that, rather than being a “transitional” period or a “hiatus” in regional occupation, the Initial Late Formative period was a distinct mode of sociality characterized by the realignment and expansion of interaction networks, on the one hand, and rejection of the decorative aesthetics, monumentality, and public-oriented performances of earlier periods, on the other. We argue that the Late Formative period centers emerging after ~AD 120 intentionally cited architecture and aesthetics that were distant in time and space, constituting a sophisticated political strategy. Finally, these data suggest that the chronological schemata we use to build regional histories often obscure social variability.

Alasdair MacIntyre’s moral approach is ranked among the very important formulations in contemporary philosophical ethics. Yet, MacIntyre and his commentators have overlooked basic requirements of teleological ethical theories (end- or goal-oriented ethical theories). In the article, we will see just where MacIntyre has erred in constructing his Aristotelian-Thomist teleological moral approach, the most fundamental error being his failure to pursue and develop ultimate ends. MacIntyre’s moral approach, which heroically attempts to combine basic ancient and medieval foundational elements while assigning social practices a prominent role in shaping moral thinking, fails to provide a determinate teleological justificatory foundation.

This article explores intraspeaker malleability in the realisation of the first-person possessive in the North-East of England ([maɪ], versus [mi] and [ma]). The analysis relies on a combination of a trend sample and a novel dynamic panel corpus that covers the entire adult lifespan. While [mi] has been around at least since the 1970s on Tyneside, [ma] appears to have made its way into the system during the 1980s and 1990s. The panel data add intraspeaker information to this ongoing change, revealing a turnover in the proportional usage of possessive variants between two recordings that are on average ten years apart. Regression modelling provides differentiated information about intraspeaker changes across the lifespan, suggesting that, with only a few exceptions, intraspeaker grammars are stable across the lifespan. The analysis supports recent panel research that has argued for the importance of considering the socio-demographic trajectory of the individual: while speakers who are part of the ‘marché scolaire’ (Bourdieu & Boltanski 1975: 7) orient towards the standard, speakers working as professional carers (e.g. nurses) tend to retain high rates of the reduced variants across their lifespans to do local identity work and establish better interpersonal relations with their clients.

This essay argues that Russia's war on Ukraine and the post-Soviet experience, more generally, reveal ethical, empirical, and theoretical problems in the study of nationalism in the region; namely, the tendency to designate anti-colonial, non-Russian nationalism as a “bad” ethnic type and the related tendency to see opposition to it as a “good” civic, nationalist agenda while in reality, the latter agenda can be imperial. Conflation of imperialism with civic nationalism and underappreciation of the democratic potential of non-Russian nationalism are problematic. The essay argues that these problems stem from theorizing about ethnic and civic nationalism that is rooted in abstract principles and does not take into account the empirical realities in which specific policies originate. I suggest that a more ethically and theoretically accurate characterization of types of nationalism as good or bad can be achieved by applying a methodology that takes into account not only formal markers of “ethnic” and “civic” policies but also the realities proponents and opponents of a given policy seek to establish and undo, the methods by which these realities come into being, and the constraints on employing illiberal methods that political actors face.

This paper uses newly digitized data on the growth of the telegraph network in America during 1840–1852 to study the impacts of the electric telegraph on national elections. Exploiting the expansion of the telegraph network in a difference-in-difference approach, I find that access to telegraphed news from Washington significantly increased voter turnout in national elections. Newspapers facilitated the dissemination of national news to local areas. Text analysis on historical newspapers shows that the improved access to news from Washington led local newspapers to cover more national political news, including coverage of Congress, the presidency, and sectional divisions involving slavery.

Using high-frequency data on over 7 million import transactions, we study the disruptions to U.S. firms’ trade patterns and growth immediately following the initial COVID-19 trade shock. While large firms were not direct recipients of government fiscal support, they experienced fewer disruptions when located in counties where small businesses (SMEs) received government stimulus loans under the Paycheck Protection Program. These effects were largest in counties with greater share of SMEs and stronger input–output linkages between large firms and SMEs. Our results point to local spillovers between SMEs and large firms as being an important determinant of firm resiliency during crises.

In this article, $\mathcal{F}_{S}(G)$ denotes the fusion category of G on a Sylow p-subgroup S of G where p denotes a prime. A subgroup K of G has normal complement in G if there is a normal subgroup T of G satisfying that G = KT and $T \cap K = 1$. We investigate the supersolvability of $\mathcal{F}_{S}(G)$ under the assumption that some subgroups of S are normal in G or have normal complement in G.

Rubicline, RbAlSi3O8, is one of three known minerals containing essential rubidium and a geochemically significant member of the feldspar family. In the course of current work, RbAlGe3O8 (germanium analogue of rubicline) was grown hydrothermally via the formation of leucite-like RbAlGe2O6 as an intermediate phase. The crystal structure of RbAlGe3O8 was determined for the first time by direct methods from single crystal X-ray diffraction data and refined to R1 = 0.0528. It has monoclinic symmetry (space group C2/m, a = 9.1237(9), b = 13.5679(6), c = 7.4677(4) Å, β = 116.687(6)° and V = 825.95(11) Å3), with cell parameters typical for disordered feldspars. According to the high-temperature study, feldspar-like RbAlGe3O8 irreversibly transforms into the leucite-like phase RbAlGe2O6 at 1050°C. The thermal expansion of studied material displays a small negative change along the b axis. Its volume thermal expansion, fitted according to a linear model between 30 and 840°C (αV = 20.3(1) ×10–6 °C–1), is slightly higher than that of other feldspar-related compounds with essential rubidium.

In this article, we study a class of convective diffusive elliptic problem with Dirichlet boundary condition and measure data in variable exponent spaces. We begin by introducing an approximate problem via a truncation approach and Yosida’s regularization. Then, we apply the technique of maximal monotone operators in Banach spaces to obtain a sequence of approximate solutions. Finally, we pass to the limit and prove that this sequence of solutions converges to at least one weak or entropy solution of the original problem. Furthermore, under some additional assumptions on the convective diffusive term, we prove the uniqueness of the entropy solution.