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We investigate the submerged collapse of weakly polydisperse, loosely packed cohesive granular columns, as a function of aspect ratio and cohesive force strength, via grain-resolving direct numerical simulations. The cohesive forces act to prevent the detachment of individual particles from the main body of the collapsing column, reduce its front velocity, and yield a shorter and thicker final deposit. All of these effects can be captured accurately across a broad range of parameters by piecewise power-law relationships. The cohesive forces reduce significantly the amount of available potential energy released by the particles. For shallow columns, the particle and fluid kinetic energy decreases for stronger cohesion. For tall columns, on the other hand, moderate cohesive forces increase the maximum particle kinetic energy, since they accelerate the initial free-fall of the upper column section. Only for larger cohesive forces does the peak kinetic energy of the particles decrease. Computational particle tracking indicates that the cohesive forces reduce the mixing of particles within the collapsing column, and it identifies the regions of origin of those particles that travel the farthest. The simulations demonstrate that cohesion promotes aggregation and the formation of aggregates. Furthermore, they provide complete information on the temporally and spatially evolving network of cohesive and direct contact force bonds. While the normal contact forces are aligned primarily in the vertical direction, the cohesive bonds adjust their preferred spatial orientation throughout the collapse. They result in a net macroscopic stress that counteracts deformation and slows the spreading of the advancing particle front.
Biblical ethics reflects upon maxims of moral behavior from the perspective of normative good and examines its legitimations and justifications, as well as the consequences of what can be called a morally positive or negative behavior. If maxims of good behavior are to be derived from historical narrative traditions, such an undertaking is confronted with the problem that implicit maxims of moral behavior are entangled with a number of other motifs and can never be isolated purely. The narratives of the Bible are subject to this challenge for any reconstruction of a historical ethos and its ethics. Their moral maxims were also anchored in the cultural contexts and ideals of their time. Although biblical narratives, including some in the book of Genesis, were ethically self-reflecting, they participated in the historicity of the cultural ideal motifs of their time.1 The solution for the resulting hermeneutical problem for any historical ethics due to the “nasty gap of history” (Gotthold Ephraim Lessing) – the tensions between modern ethical maxims and those of the Bible – is the main problem for any biblical ethics of the Torah or more specifically, the book of Genesis.
Describe nutrition and physical activity practices, nutrition self-efficacy and barriers and food programme knowledge within Family Child Care Homes (FCCH) and differences by staffing.
Design:
Baseline, cross-sectional analyses of the Happy Healthy Homes randomised trial (NCT03560050).
Setting:
FCCH in Oklahoma, USA.
Participants:
FCCH providers (n 49, 100 % women, 30·6 % Non-Hispanic Black, 2·0 % Hispanic, 4·1 % American Indian/Alaska Native, 51·0 % Non-Hispanic white, 44·2 ± 14·2 years of age. 53·1 % had additional staff) self-reported nutrition and physical activity practices and policies, nutrition self-efficacy and barriers and food programme knowledge. Differences between providers with and without additional staff were adjusted for multiple comparisons (P < 0·01).
Results:
The prevalence of meeting all nutrition and physical activity best practices ranged from 0·0–43·8 % to 4·1–16·7 %, respectively. Average nutrition and physical activity scores were 3·2 ± 0·3 and 3·0 ± 0·5 (max 4·0), respectively. Sum nutrition and physical activity scores were 137·5 ± 12·6 (max 172·0) and 48·4 ± 7·5 (max 64·0), respectively. Providers reported high nutrition self-efficacy and few barriers. The majority of providers (73·9–84·7 %) felt that they could meet food programme best practices; however, knowledge of food programme best practices was lower than anticipated (median 63–67 % accuracy). More providers with additional staff had higher self-efficacy in family-style meal service than did those who did not (P = 0·006).
Conclusions:
Providers had high self-efficacy in meeting nutrition best practices and reported few barriers. While providers were successfully meeting some individual best practices, few met all. Few differences were observed between FCCH providers with and without additional staff. FCCH providers need additional nutrition training on implementation of best practices.
The reforms initiated by Reza Shah's urban modernization drive led to changes not only in cultural patterns of urban life in Iran and the economic structure of the country, but even in spatial organization. The full effect of these initiatives only started to be felt under Mohammad Reza Shah, who continued to pursue the policy of his predecessor. For our specific purpose—urban change under Reza Shah—we will focus on an analysis of the development of the Iranian city, specifically the following three aspects: spatial reorganization; economic changes; and consequences of urban change.
Our basic assumption is that the city, unlike any other phenomenon, became the symbol of political and socioeconomic transformation in Iran and that, to this day, it has preserved this character of Pahlavi modernization and change like no other institution or phenomenon.
By Definition, an Encyclopaedia is “A Work that Aims at Giving a comprehensive summary of all branches of knowledge… Encyclopaedias usually consist of articles on separate subjects arranged in dictionary or alphabetical order to facilitate use… .” A more differentiated view is given by the New Encyclopaedia Britannica, which describes encyclopaedias as follows: “Today most people think of an encyclopaedia as a multivolume compendium of all available knowledge, complete with maps and a detailed index, as well as numerous adjuncts such as bibliographies, illustrations, list of abbreviations and foreign expressions, gazetteers, and so on…”
Unlike the Encyclopaedia Americana or the Encyclopaedia Britannica, whose primary goals have been and still are to serve as comprehensive and always up-to-date works of reference of general knowledge, the Encyclopaedia Iranica would fall under the category of specialized encyclopaedias “that have deliberately been planned for a special purpose” or even better: encyclopaedias of countries and regions “dealing with a single country and region.”
The chapter tries to establish a systematic framework which allows us to structure the examination of human rights cases by indicating the necessary legal components and putting these elements in their proper place and in context to each other. Substantive human rights guarantees as, e.g., enshrined in the International Covenant on Civil and Political Rights or the European Convention, cannot be fully understood without taking account of their explicit or implicit limitations; only together do they form the basis for their successful invocation. Therefore the legal limits of and restrictions to human rights as well as the limitations drawn to the use of restrictions, as particularly the principle of proportionality, are discussed. Primacy of freedom, (strict) interpretation, balancing of rights, absolute rights, margin of appreciation and derogation from human rights are other issues that have to be dealt with in the given context.
Emerging technologies such as deep-sea mining and geoengineering pose fundamentally new questions regarding the dynamics of gravity currents. Such activities can continuously release dense sediment plumes from moving locations, thereafter propagating as gravity currents. Here, we present the results of idealized numerical simulations of this novel configuration, and investigate the propagation of a gravity current that results from a moving source of buoyancy, as a function of the ratio of source speed to buoyancy velocity. We show that above a certain value of this ratio, the flow enters a supercritical regime in which the source moves more rapidly than the generated current, resulting in a statistically steady state in the reference frame of the moving source. Once in the supercritical regime, the current goes through a second transition beyond which fluid in the head of the current moves approximately in the direction normal to the direction of motion of the source, and the time evolution of the front in the lateral direction is well described by an equivalent constant volume lock-release gravity current. We use our findings to gain insight into the propagation of sediment plumes released by deep-sea mining collector vehicles, and present proof-of-concept tow-tank laboratory experiments of a model deep-sea mining collector discharging dense dyed fluid in its wake. The experiments reveal the formation a wedge-shaped gravity current front which narrows as the ratio of collector-to-buoyancy velocity increases. The time-averaged front position shows good agreement with the results of the numerical model in the supercritical regime.
We investigate the removal of a dense bottom layer by a gravity current, via Navier–Stokes simulations in the Boussinesq limit. The problem is governed by a dimensionless thickness parameter for the bottom layer, and by the ratio of the density differences between bottom layer, gravity current and ambient fluids. A quasisteady gravity current forms that propagates along the interface and displaces some of the dense bottom fluid, which accumulates ahead of the gravity current and forms an undular bore or a series of internal gravity waves. Depending on the ratio of the gravity current front velocity to the linear shallow-water wave velocity, we observe the existence of different regimes, characterized by small-amplitude waves or by a train of steep, nonlinear internal waves. We develop a semiempirical model that provides reasonable estimates of several important flow properties. We also formulate a more sophisticated, self-contained model based on the conservation principles for mass and vorticity that does not require empirical closure assumptions. This model is able to predict such quantities as the gravity current height and the internal wave or bore velocity as a function of the governing dimensionless parameters, generally to within approximately a 10 $\%$ accuracy. An energy budget analysis provides information on the rates at which potential energy is converted into kinetic energy and then dissipated, and on the processes by which energy is transferred from the gravity current fluid to the dense and ambient fluids. We observe that the energy content of thicker and denser bottom layers grows more rapidly.
We study to what extent the Milky Way was used as an orientation tool at the beginning of the Islamic period covering the 8th to the 15th century, with a focus on the first half of that era. We compare the texts of three authors from three different periods and give detailed comments on their astronomical and traditional content. The text of al-Marzūqī summarises the information on the Milky Way put forward by the astronomer and geographer ʾAbū Ḥanīfa al-Dīnawarī. The text makes it clear that in some areas the Milky Way could be used as a geographical guide to determine the approximate direction toward a region on Earth or the direction of prayer. In the 15th century, the famous navigator Aḥmad b. Māǧid describes the Milky Way in his nautical instructions. He frequently demonstrates that the Milky Way serves as a guidance aid to find constellations and stars that are useful for precise navigation on land and at sea. On the other hand, Ibn Qutayba quotes in his description of the Milky Way a saying from the famous Bedouin poet Ḏū al-Rumma, which is also mentioned by al-Marzūqī. In this saying the Milky Way is used to indicate the hot summer times in which travelling the desert was particularly difficult. Hence, the Milky Way was useful for orientation in space and time and was used for agricultural and navigational purposes.
Laboratory experiments and direct numerical simulations are employed to investigate lock-exchange gravity currents propagating over close-packed, fixed porous beds of monodisperse spherical particles, and to quantify the mass and momentum transfer between the currents and the bed. The simulations show that the mass exchange of the current with the bed involves two separate steps that operate on different time scales. In a first step, the dense current front rapidly sweeps away the resident fluid in the exposed pore spaces between the top layer of spheres, while in a second step, a buoyancy-driven vertical exchange flow between the current and the deeper pores is set up that takes significantly longer to develop. This process depends on the permeability of the bed, which in turn is a function of the particle diameter. The momentum exchange between the current and the bed strongly depends on the ratio of the particle size to the viscous sublayer of the current. The bottom friction is moderate when the particle size is smaller than or comparable to the thickness of the viscous sublayer, but it jumps for particles that strongly protrude from the sublayer, leading to a more rapid deceleration of the flow.
When the density of a gravitationally stable fluid depends on a fast diffusing scalar and a slowly diffusing scalar of opposite contribution to the stability, ‘double diffusive’ instabilities may develop and drive convection. When the slow diffuser settles under gravity, as is for instance the case for small sediment particles in water, settling-driven double-diffusive instabilities can additionally occur. Such instabilities are relevant in a variety of naturally occurring settings, such as particle-laden river discharges, or underground inflows in lakes. Inspired by the dynamics of the more traditional thermohaline double-diffusive instabilities, we ask whether large-scale ‘mean-field’ instabilities can develop as a result of sedimentary double-diffusive convection. We first apply the mean-field instability theory of Traxler et al. (J. Fluid Mech., vol. 677, 2011, pp. 530–553) to high-Prandtl-number fluids, and find that these are unstable to Radko's layering instability, yet collectively stable. We then extend the theory of Traxler et al. (2011) to include settling and study its impact on the development of the collective instability. We find that two distinct regimes exist. At low settling velocities, the double-diffusive turbulence in the fingering regime is relatively unaffected by settling and remains stable to the classical collective instability. It is, however, unstable to a new instability in which large-scale gravity waves are excited by the phase shift between the salinity and particle concentration fields. At higher settling velocities, the double-diffusive turbulence is substantially affected by settling, and becomes unstable to the classic collective instability. Our findings, validated by direct numerical simulations, reveal new opportunities to observe settling-driven layering in laboratory and field experiments.
We show how settling and phase change can combine to drive an instability, as a simple model for the formation of mammatus clouds. Our idealised system consists of a layer (an ‘anvil’) of air mixed with saturated water vapour and monodisperse water droplets, sitting atop dry air. The water droplets in the anvil settle under gravity due to their finite size, evaporating as they enter dry air and cooling the layer of air just below the anvil. The colder air just below the anvil thus becomes denser than the dry air below it, forming a density ‘overhang’, which is unstable. The strength of the instability depends on the density difference between the density overhang and the dry ambient, and the depth of the overhang. Using linear stability analysis and nonlinear simulations in one, two and three dimensions, we study how the amplitude and depth of the density layer depend on the initial conditions, finding that their variations can be explained in terms only of the size of the droplets making up the liquid content of the anvil and by the total amount of liquid water contained in the anvil. We find that the size of the water droplets is the controlling factor in the structure of the clouds: mammatus-like lobes form for large droplet sizes; and small droplet sizes lead to a ‘leaky’ instability resulting in a stringy cloud structure resembling the newly designated asperitas.
A series of well-preserved specimens of the little-known Palaeogene species Biselenaria placentula (Reuss, 1867) warrant the designation of a new family of free-living cheilostome bryozoans, Biselenariidae n. fam. In contrast to the structural organization of all other free-living, lunulitiform cheilostomes, all zooids are enclosed almost completely by cuticular, exterior walls. Yet, like other lunulitiforms, the colony must be regarded as a highly integrated functional unit, as revealed through the unique, highly complex interior architecture. In creating the new monotypic family, the type species Biselenaria placentula is described in detail, while the ambiguous taxonomic status of the only other taxon, B. offa Gregory, 1893, is discussed.
– Earlier studies on the influence of pregnancy and postpartum period on the course of panic disorder have been inconsistent. The present study aims to quantify panic manifestations in these periods in large sample of women.
Method
– Panic manifestations, including exacerbations and new manifestations of panic disorder, were assessed retrospectively in a sample of 128 women with panic disorder with or without agoraphobia, 93 of whom had had 195 pregnancies.
Results
– Panic manifestations were fewer during pregnancy and more frequent in the postpartum period when compared with the control period. Women who had never been pregnant had significantly more panic manifestations than women with prior pregnancies. Breastfeeding and miscarriages did not have a significant effect. Women with postpartum panic reported more psychosocial stress events during this period.
Conclusions
– Possible reasons for postpartum panic and the protective effects of pregnancy are discussed, including psychosocial or hormonal factors and other neurobiological changes. Postpartum panic coincides with a sudden drop of hormones after delivery.
Applying broad notions of adaptation, this chapter seeks to bring “recombinant adaptation” – mashups and remixes on digital platforms – in dialogue with Gerard Genette's idea of the paratext as a text's “relations with the public.” It takes four steps towards investigating how literary publishing houses such as Quirk Books respond to recombinant adaptation. Firstly, it delineates the paratexts of mashup novels as performative zones of transaction. Secondly, it examines the question of how paratexts regulate the quasi-religious textuality of fandom participation. Thirdly, it looks at the role of paratextual canonization within this textuality. And finally, it argues that printed products within the field attempt to perform a nostalgic authorization and re-materialization of literature, highlighting the haptic and material qualities of the book. Adapting the term “polytext,” the chapter calls these multifarious paratextual transactions the “polyprocess.”
This essay seeks to bring the field of “recombinant adaptation” – mashups and remixes on digital platforms – in dialogue with the Genettian idea of the paratext. Genette held that paratexts shape a given text's “relations with the public.” More recently, Jonathan Gray has applied the notion of paratext to media franchises, highlighting the active role of paratexts in creating and continuing franchise texts. Dorothee Birke and Birte Christ have elaborated Genette's ideas for a situation of convergence culture and transmedia storytelling, examining how paratexts fulfill interpretive, commercial, or navigational functions in determining contemporary readers’ transmedia experience of narratives.
This chapter takes four steps towards investigating how literary publishing houses respond to the ubiquitous remixes and mashups to be found on lowthreshold digital platforms of participation. It will, first, delineate paratexts as zones of transaction, shifting research emphases from textual towards performative concerns and highlighting the way cultures negotiate textual distribution and circulation. Secondly, it will examine the question of how paratexts regulate the quasi-religious textuality of fandom participation; thirdly, the role of paratextual canonization will be a special focus within this textuality. Finally, the chapter argues that printed products within the field attempt to perform a nostalgic authorization and re-materialization of literature, highlighting the haptic and material qualities of “bookishness.”
Ibn Raḥīq is an 11th century scholar who compiled a book on popular astronomy. This work included a section in which he summarizes basic knowledge of the Milky Way as it was wide spread in the first centuries after the hejira. Ibn Raḥīq gives a comprehensive overview of the perception of the Milky Way that reaches from its use as a test for knowledge of the religious tradition and for agricultural purposes on the one hand to an exact astronomical description of its shape in the sky during the year and to theories of its nature and composition on the other hand. We use a comparison of his text to those of Ibn al-Haytham and others to investigate the role the Milky Way played in early Islamic civilization from its beginning until the 15th century.
We investigate the interaction of a downslope gravity current with an internal wave propagating along a two-layer density jump. Direct numerical simulations confirm earlier experimental findings of a reduced gravity current mass flux, as well as the partial removal of the gravity current head from its body by large-amplitude waves (Hogg et al., Environ. Fluid Mech., vol. 18 (2), 2018, pp. 383–394). The current is observed to split into an intrusion of diluted fluid that propagates along the interface and a hyperpycnal current that continues to move downslope. The simulations provide detailed quantitative information on the energy budget components and the mixing dynamics of the current–wave interaction, which demonstrates the existence of two distinct parameter regimes. Small-amplitude waves affect the current in a largely transient fashion, so that the post-interaction properties of the current approach those in the absence of a wave. Large-amplitude waves, on the other hand, perform a sufficiently large amount of work on the gravity current fluid so as to modify its properties over the long term. The ‘decapitation’ of the current by large waves, along with the associated formation of an upslope current, enhance both viscous dissipation and irreversible mixing, thereby strongly reducing the available potential energy of the flow.
Edited by
Beatrice de Graaf, Universiteit Utrecht, The Netherlands,Ido de Haan, Universiteit Utrecht, The Netherlands,Brian Vick, Emory University, Atlanta
As a historical model of how to end an extended period of international conflict and to establish a stable and peaceful international order, the Vienna Congress has claimed the attention of academics and politicians ever since 1815. Against this background the chapter will deal with the question of how the Congress of Vienna and the Vienna system were regarded by various actors and under changing political circumstances. Rather than merely collecting views and interpretations of the Congress and the international system taking shape in 1814/15, the chapter will ask how the varying interpretations of Vienna and the Vienna system reflected changing ideas and visions of international order and what they can tell us about national and international security cultures in the nineteenth and twentieth centuries.
Miscible liquids often come into contact with one another in natural and technological situations, commonly as a drop of one liquid present in a second, miscible liquid. The shape of a liquid droplet present in a miscible environment evolves spontaneously in time, in a distinctly different fashion than drops present in immiscible environments, which have been reported previously. We consider drops of two classical types, pendant and sessile, in building upon our prior work with miscible systems. Here we present experimental findings of the shape evolution of pendant drops along with an expanded study of the spreading of sessile drops in miscible environments. We develop scalings considering the diffusion of mass to group volumetric data of the evolving pendant drops and the diffusion of momentum to group leading-edge radial data of the spreading sessile drops. These treatments are effective in obtaining single responses for the measurements of each type of droplet, where the volume of a pendant drop diminishes exponentially in time and the leading-edge radius of a sessile drop grows following a power law of $t^{1/2}$ at long times. A complementary numerical approach to compute the concentration and velocity fields of these systems using a simplified set of governing equations is paired with our experimental findings.