Неустойчивость двухслойных течений в проливах Черного моря

Рассмотрена плоская задача о прогрессивных гравитационных внутренних волнах в горизонтальном двухслойном течении Кельвина-Гельмгольца. Найдено аналитическое решение задачи и условия существования внутренних волн. Для течений с параметрами, типичными для пролива Босфор и Керченского пролива, рассчитаны характеристики бароклинных волн. В пространстве волновых чисел определены диапазоны устойчивости и неустойчивости двухслойных течений с характерными для этих проливов параметрами относительно малых возмущений в форме прогрессивных волн.Розглянуто плоску задачу про прогресивні гравітаційні внутрішні хвилі у горизонтальній двошаровій течії Кельвіна-Гельмгольца. Знайдено аналітичне рішення задачі та умови існування внутрішніх хвиль. Для течій з параметрами, типовими для протоки Босфор і Керченської протоки, розраховані характеристики бароклінних хвиль. У просторі хвильових чисел визначені діапазони стійкості і нестійкості двошарових течій з характерними для цих проток параметрами відносно малих збурень у формі прогресивних хвиль.The plane problem of the progressive internal gravity waves in a horizontal two-layer Kelvin-Helmholtz flow is considered. The analytical solution of the problem and the conditions of existence of internal waves are found. For the flows with the typical parameters for the Bosphorus Strait and the Strait of Kerch, characteristics of baroclinic waves are calculated. The stability and instability regimes of two-layer currents with characteristic parameters of these straits with respect to small wave disturbances are found in the space of wave numbers

Three dimensions of central bank credibility and inferential expectations: The Euro zone

We use the behavior of inflation among Eurozone countries to provide information about the degree of credibility of the European Central Bank (ECB) since 2008. We define credibility along three dimensions–official target credibility, cohesion credibility and anchoring credibility–and show in a new econometric framework that the latter has deteriorated in recent history; that is, price setters are less likely to rely on the ECB target when forming inflation expectations

Developing the potential for change: Challenging power through social entrepreneurship in the Netherlands

Most research on social entrepreneurship overemphasizes agency by presenting social enterprising as something that originates solely from the intrinsic motivations of individual entrepreneurs. Research that does regard the impact of state power is almost exclusively anchored in and geared toward neoliberal policy contexts. This article examines the dialectics between state power and entrepreneurial counterpower in the institutional context of the Netherlands. Moreover, since social entrepreneurs develop different tactics and strategies for responding to challenges, we use Gaventa’s power cube to distinguish forms of power and counterpower, which we then combine with the following inductively derived social entrepreneur typologies: successful hybrids, antagonistic organizers, and autonomous entrepreneurs. This offers insights into the development of theory in relation to the social entrepreneurial potential for change and civic participation

Scalariform-to-simple transition in vessel perforation plates triggered by differences in climate during the evolution of Adoxaceae

Background and Aims Angiosperms with simple vessel perforations have evolved many times independently of species having scalariform perforations, but detailed studies to understand why these transitions in wood evolution have happened are lacking. We focus on the striking difference in wood anatomy between two closely related genera of Adoxaceae, Viburnum and Sambucus, and link the anatomical divergence with climatic and physiological insights.[br/] Methods After performing wood anatomical observations, we used a molecular phylogenetic framework to estimate divergence times for 127 Adoxaceae species. The conditions under which the genera diversified were estimated using ancestral area reconstruction and optimization of ancestral climates, and xylem-specific conductivity measurements were performed.[br/] Key Results Viburnum, characterized by scalariform vessel perforations (ancestral), diversified earlier than Sambucus, having simple perforations (derived). Ancestral climate reconstruction analyses point to cold temperate preference for Viburnum and warm temperate for Sambucus. This is reflected in the xylem-specific conductivity rates of the co-occurring species investigated, showing that Viburnum lantana has rates much lower than Sambucus nigra.[br/] Conclusions The lack of selective pressure for high conductive efficiency during early diversification of Viburnum and the potentially adaptive value of scalariform perforations in frost-prone cold temperate climates have led to retention of the ancestral vessel perforation type, while higher temperatures during early diversification of Sambucus have triggered the evolution of simple vessel perforations, allowing more efficient long-distance water transport

Scalariform-to-simple transition in vessel perforation plates triggered by differences in climate during the evolution of Adoxaceae

Background and Aims Angiosperms with simple vessel perforations have evolved many times independently of species having scalariform perforations, but detailed studies to understand why these transitions in wood evolution have happened are lacking. We focus on the striking difference in wood anatomy between two closely related genera of Adoxaceae, Viburnum and Sambucus, and link the anatomical divergence with climatic and physiological insights.[br/] Methods After performing wood anatomical observations, we used a molecular phylogenetic framework to estimate divergence times for 127 Adoxaceae species. The conditions under which the genera diversified were estimated using ancestral area reconstruction and optimization of ancestral climates, and xylem-specific conductivity measurements were performed.[br/] Key Results Viburnum, characterized by scalariform vessel perforations (ancestral), diversified earlier than Sambucus, having simple perforations (derived). Ancestral climate reconstruction analyses point to cold temperate preference for Viburnum and warm temperate for Sambucus. This is reflected in the xylem-specific conductivity rates of the co-occurring species investigated, showing that Viburnum lantana has rates much lower than Sambucus nigra.[br/] Conclusions The lack of selective pressure for high conductive efficiency during early diversification of Viburnum and the potentially adaptive value of scalariform perforations in frost-prone cold temperate climates have led to retention of the ancestral vessel perforation type, while higher temperatures during early diversification of Sambucus have triggered the evolution of simple vessel perforations, allowing more efficient long-distance water transport