In this article, we consider the global-in-time existence and singularity formation of smooth solutions for the radially symmetric relativistic Euler equations of polytropic gases. We introduce the rarefaction/compression character variables for the supersonic expanding wave with relativity and derive their Riccati type equations to establish a series of priori estimates of solutions by the characteristic method and the invariant domain idea. It is verified that, for rarefactive initial data with vacuum at the origin, smooth solutions will exist globally. On the other hand, the smooth solution develops a singularity in finite time when the initial data are compressed and include strong compression somewhere.

In recent years, prominent Republican elites have instituted statewide migrant transportation programs in which asylum-seeking migrants are “bused” to liberal cities across the country. These programs are often justified by invoking NIMBYism (not-in-my-backyard), suggesting that when people must consider the effects of immigration policy in terms of their community, their attitudes toward immigrants will vary. Despite this, extant scholarship has yet to document the extent to which American immigration preferences vary by spatial scale and gives no expectation about how important any variation is relative to other determinants of immigration attitudes. Findings from a conjoint experiment reveal that Americans, on average, oppose immigrants proposed to move into their neighborhoods, but spatial scale does not alter considerations at the national, state, or city level. The relative importance of this NIMBY effect, however, is modest compared to a host of other individual-level characteristics of an immigrant. Moreover, despite elite claims of “liberal hypocrisy” in immigration, we find no evidence that the NIMBY effect varies by partisanship. Both Democrats and Republicans exhibit modest preferences against immigrants expected to move to their neighborhoods.

Indigenous communities have long been marginalized and underrepresented in democracies, yet we know little about how publics evaluate Indigenous people who are thinking of running as candidates. Using two experimental surveys with nationally representative samples of Australian adults, we examine how citizens assess the personality traits of eight women and men who are interested in running for office. All eight have identical biographies, other than the fact that they are from White, Chinese, and both dark-skinned and light-skinned Indigenous Australian backgrounds. Surprisingly, we find an inverted hierarchy of bias, moderated by respondent ideology, in which darker-skinned Indigenous potential candidates fare better than all others. Although this may be due to a positive violation of expectations, our results have implications for theories about how people view Indigenous and ethnic minority aspirant politicians. They also point to the need for further research globally into how the public and parties evaluate Indigenous candidates.

We inquire how a commodity cartel is created by studying the negotiations between Colombia and Brazil to stabilize the international coffee market in the 1930s. We show how differences among actors involved in the industry within the negotiating countries in terms of land ownership and type of coffee produced, prevented early cartelization agreements. Cartelization was only achieved when four factors converged: financial and infrastructural capability to store excess production, in-depth knowledge of the industry by the negotiating parties, full government support, and presence of a third-party enforcer. We combine an innovative game-theoretic approach with previously unexplored archival sources.

We prove that there is an absolute constant $C{\,\gt\,}0$ such that every k-vertex connected rainbow graph R with minimum degree at least $C\log k$ has inducibility $k!/(k^k-k)$. The same result holds if $k\ge 11$, and R is a clique. This answers a question posed by Huang, that is a generalisation of an old problem of Erdös and Sós. It remains open to determine the minimum k for which this is true.

This paper presents the palaeoecological analysis of five latest Pleistocene (17,500–13,500 cal yr BP) Arctic ground squirrel (Urocitellus parryii) middens from three sites in the Klondike goldfields of central Yukon Territory. Plant and invertebrate macrofossil records were represented by 24 and 20 taxa, respectively, providing a record of the local environment and the earliest known occurrences in Yukon Territory for several taxa (e.g., the robber fly [Lasiopogon sp.] and marsh yellowcress [Rorippa cf. palustris]). The plant and invertebrate assemblages indicate the persistence of steppe-tundra to at least 13,680 cal yr BP by the preservation of taxa typically occupying dry sites, many of which remain components of grasslands and south-facing azonal steppe communities in present-day Yukon Territory. In the context of shrub expansion that is documented to have occurred by 14,000 cal yr BP in interior Alaska, we consider the taphonomic biases associated with Arctic ground squirrel middens that may lead to the lack of shrub macrofossils preserved at the sites. Our study provides an ecologically unique and chronologically constrained perspective on the local persistence of steppe-tundra in easternmost Beringia despite the regional expansion of shrubs.

Germany’s 2023 Feminist Foreign Policy (FFP) Guidelines commit to a transformative, intersectional agenda across diplomacy, security, and climate policy, but omit migration. This article examines how and why migration was excluded, despite its centrality to foreign policy and the involvement of civil society in the drafting process. Drawing on practice theory, Black feminist and postcolonial scholarship, we analyze state–civil society consultations as a community of practice shaped by epistemic hierarchies based on race and coloniality. We show how the Foreign Office’s reliance on established, Germany-based policy actors with limited expertise in gendered mobility sidelined migration as a feminist concern. The consultation format constrained participation and reinforced boundaries around what counted as legitimate feminist knowledge. Bridging literature on migration and FFP, the article advances understandings of how institutional and epistemic power shape feminist policy-making. It calls for a more inclusive FFP attentive to the gendered and racialized dynamics of mobility.

During the Ordovician, the brachiopod order Atrypida originated and diversified. However, speciation patterns and evolutionary drivers within three atrypide Laurentian genera, Anazyga, Catazyga, and Zygospira, remain poorly known. Herein, we propose a Bayesian phylogenetic framework for these clades. Morphological character data, including 34 internal and external characters, were collected for 20 species, including seven species assigned to Zygospira, six species previously assigned to Anazyga, and seven species previously assigned to Catazyga. Morphological data were analyzed in BEAST2.5 via an Mk Model of morphological character evolution implementing the fossilized birth–death (FBD) model. In addition, FBD-based rates of extinction, origination, and fossil sampling were estimated across four Late Ordovician time intervals. Primary results include: (1) each genus was polyphyletic as traditionally established; (2) proposed transfer of all Anazyga and two Catazyga species to Zygospira based on reconstructed evolutionary relationships; (3) recognition of one new species, Zygospira idahoensis Vilela-Andrade n. sp., and the elevation of Z. multicostata Howe, 1965, originally a subspecies, to species status; and (4) updated understanding of clade origination and speciation. The origination age for the clade is calibrated to be 453 Ma (Sandbian 2). Recovered biodiversification rates indicate that the highest speciation and extinction rates occurred in the Katian 3 stage slice, when the number of species in the clade peaked. Subsequently, a decline in biodiversification led to an extinction episode in the Katian 4 for all lineages. Catazyga and Zygospira are interpreted as early Late Ordovician atrypids that experienced both rapid radiation and extinction during the Katian.

UUID: http://zoobank.org/442febc2-f7bb-4c04-b454-d43180237ebc

Afrikaans is spoken by a wide range of ethnic groups in Namibia, both as an L1 and an L2. Stell (2021) showed that, in its phonetic variation, Namibian Afrikaans forms a continuum between Whites and Blacks with Coloureds1 located in between. This article aims to find out whether a continuum can likewise be observed in the grammatical patterns of Namibian Afrikaans varieties. The dataset is based on a translation task, administered to L1 Afrikaans-speaking Whites and Coloureds and to L2 Afrikaans-speaking Damaras and Ovambos, whose respective L1s are Khoekhoegowab and Oshiwambo. The article finds a contrast between L1 and L2 speakers as the Damara and Ovambo Afrikaans varieties show evidence of L1 transfers. However, it also finds evidence of a continuum linking the Whites, Coloureds, and Damaras in the form of commonly shared Orange River Afrikaans features. The fact that Ovambo Afrikaans does not quite fit into this continuum, the article argues, has to do with the historically late exposure of Oshiwambo speakers to L1 Afrikaans varieties. Finally, the article attempts to match evidence of Khoekhoegowab influence on Damara Afrikaans with Den Besten’s (2001) and Roberge’s (1994a) reflections on historical contact between Khoekhoe and Cape Dutch.

This study reconstructs the fluvial dynamics of the Bras de Fer distributary in the Rhône Delta (France) during the Little Ice Age (LIA) in response to short-term climatic forcing. A multiproxy approach combining historical cartography, sedimentology, geochemistry, magnetic susceptibility, and hydrological archives reveals accelerated meander migration and extensive overbank accretion between the late seventeenth and early eighteenth centuries CE. Increased flood frequency, coinciding with positive phases of the Atlantic Multidecadal Oscillation (AMO+), promoted rapid lateral channel shifts and the formation of crevasse splay complexes along the outside bank of the Grande Ponche meander. The results demonstrate that, despite stable relative sea levels, deltaic morphology remained highly sensitive to decadal-scale climatic variability, highlighting the dominant role of hydrological extremes in shaping fluvial-deltaic environments of Rhône delta during the late LIA.

How does racial inequality shape who dies in war? Focusing on the era of United States military segregation, we argue that discriminatory societal institutions and prejudicial attitudes combined to reduce commanders’ beliefs about Black soldiers’ combat effectiveness. These biased assessments decreased the likelihood that Black soldiers were assigned combat occupational specialties, and that Black combat units received key frontline assignments. However, commanders’ biases also created a desire to preserve white lives. Accordingly, we expect Black soldiers received worse support. These choices shaped soldiers’ risk of death. Analyzing the case of World War I (WWI), we leverage data on over 44,000 infantry fatalities and show that white units incurred four times as many combat fatalities as comparable Black units. However, holding fixed exposure to combat, Black units suffered higher levels of noncombat deaths. Commanders thus deemed Black soldiers insufficiently qualified to fight as equals, but sufficiently expendable to die in war’s least consequential conditions.

This paper provides a preliminary investigation into the use of a novel passive aircraft flight loads alleviation device called the Superelastic Monostable Spoiler. The work focuses primarily on understanding the behaviour of such a device and the related loads alleviation performance during dynamic gust events. A number of different design parameters are explored, such as the trigger condition and the activation speed. The main aim of the paper is to define the preliminary operational requirements of such a device in order to guide the future detailed design, which is not addressed here. It was found that the Superelastic Monostable Spoiler could potentially provide loads alleviation performance comparable with typical gust loads alleviation technologies currently used in modern civil aviation based on the use of ailerons and spoilers.

We give a new criterion which guarantees that a free group admits a bi-ordering that is invariant under a given automorphism. As an application, we show that the fundamental group of the “magic manifold” is bi-orderable, answering a question of Kin and Rolfsen.