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Turbulent flows above a solid surface are characterised by a hydrodynamic roughness that represents, for the far velocity field, the typical length scale at which momentum mixing occurs close to the surface. Here, we are theoretically interested in the hydrodynamic roughness induced by a two-dimensional modulated surface, the elevation profile of which is decomposed in Fourier modes. We describe the flow for a sinusoidal mode of given wavelength and amplitude with Reynolds-averaged Navier–Stokes equations closed by means of a mixing-length approach that takes into account a possible surface geometrical roughness as well as the presence of a viscous sublayer. It also incorporates spatial transient effects at the laminar–turbulent transition. Performing a weekly nonlinear expansion in the bedform aspect ratio, we predict the effective hydrodynamic roughness when the surface wavelength is varied and we show that it presents a non-monotonic behaviour at the laminar–turbulent transition when the surface is hydrodynamically smooth. Further, with a self-consistent looped calculation, we are able to recover the smooth–rough transition of a flat surface, for which the hydrodynamic roughness changes from a regime where it is dominated by the viscous length to another one where it scales with the surface corrugation. We finally apply the results to natural patterns resulting from hydrodynamic instabilities such as those associated with dissolution or sediment transport. We discuss in particular the aspect ratio selection of dissolution bedforms and roughness hierarchy in superimposed ripples and dunes.
With the recent advances in artificial intelligence (AI), patients are increasingly exposed to misleading medical information. Generative AI models, including large language models such as ChatGPT, create and modify text, images, audio and video information based on training data. Commercial use of generative AI is expanding rapidly and the public will routinely receive messages created by generative AI. However, generative AI models may be unreliable, routinely make errors and widely spread misinformation. Misinformation created by generative AI about mental illness may include factual errors, nonsense, fabricated sources and dangerous advice. Psychiatrists need to recognise that patients may receive misinformation online, including about medicine and psychiatry.
The study clarified differences in understanding and satisfaction between face-to-face and online training on radiation emergency medical preparedness (REMP) training.
Methods:
The training was held at Hirosaki University between 2018 and 2022, with 46 face-to-face participants and 25 online participants.
Results:
Face-to-face training was significantly more understandable than online for the use of the Geiger counter (P < 0.05), but the educational effect of virtual reality (VR) was not significantly different from the actual practice. For the team exercise of taking care of the victims, online resulted in a significantly higher understanding (P < 0.05).
Conclusions:
Interactive exercises can be done online with equipment sent to learners, and VR is also as effective. The use of videos was more effective for first-timers to learn the practical process from a bird’s-eye view, especially for team-based medical procedures.
A theoretical and experimental investigation of two-dimensional (2-D) liquid curtains (gravitationally thinning liquid sheets) is provided under conditions where the curtain issues from a thin slot whose centreline is inclined with respect to the vertical. This analysis is motivated in part by recent works where it has been proposed that oblique liquid curtains (those exiting a non-vertical slot) may bend upwards against gravity when the relevant Weber number at the slot is less than unity ($We <1$). By contrast, Weinstein et al. (J. Fluid Mech., vol. 876, 2019, R3) have proposed that such $We<1$ curtains must be vertical and downward falling regardless of the inclination of the slot. Under low-Reynolds-number ($Re$) conditions typical of liquid film coating operations, our experiments show that the curtain shape follows the classic ballistic (parabolic) trajectory in the supercritical regime ($We>1$). In subcritical conditions ($We<1$), experiments show that the downward-falling curtain is vertical except in a relatively small region near the slot, where the combined effects of viscosity and surface tension induce the so-called teapot effect. These experimental results are confirmed by 2-D numerical simulations, which predict the curtain behaviour ranging from highly viscous ($Re = O(1)$) to nearly inviscid conditions. The one-dimensional (1-D) inviscid model of Weinstein et al. is recast in a different form to facilitate comparisons with the 2-D model, and 1-D and 2-D results agree favourably for supercritical and subcritical conditions. Despite the large parameter range explored, we have found no evidence that upward-bending curtains exist in an oblique configuration.
The Netherlands recently experienced a crisis in childcare benefits, leading to ‘unprecedented injustice’ for many parents falsely accused of defrauding the childcare benefit system. This crisis highlights multiple barriers in parents’ ability to access childcare already evident prior to the crisis, including the far-reaching digitalisation of social policies and childcare benefits in particular. Digitalisation can make parents feel childcare services are less accessible, thereby creating or exacerbating existing inequalities in childcare use. Parents may also lack the skills needed to navigate complex application procedures, which can affect their perceived access to childcare benefits, particularly in market-led systems with greater reliance on government benefits to cover the high costs of childcare. Extending recent research on childcare capabilities, we investigate the extent to which digital and functional literacy affect parents’ perceived access to childcare benefits in the Netherlands. The results from our exploratory quantitative analysis provide a starting point for understanding the understudied relationships between digitalisation, parents’ abilities to navigate complex childcare or other policy systems, and their (perceived) ability to access childcare benefits. We use these findings to develop multiple future research recommendations in the childcare policy literature.
During the Second World War, the British Government interned or asked the Holy See to replace many of the Italian clergy within the territories that it controlled. This led to a political conflict between London and the Vatican which was not resolved until the end of the war. This article addresses the development of the controversy and its causes, concluding that it stemmed from traditional imperial hegemonic goals rather than from anti-Catholicism. It also stresses that the Church's response was weakened by national rivalries within the Catholic clergy in the region, and the fundamentally different views of the war of London and the Vatican.
We investigate the gender gap in issue attention among members of parliament (MPs) by applying automated text analytic techniques to a novel data set on Italian parliamentary speeches over a remarkably long period (1948–2020). We detect a gendered specialization across issues that tends to disappear as women’s shares in parliamentary groups increase. We then investigate whether women’s access to previously male-owned issues brings with it a different agenda, operationalized as a different vocabulary. We detect a U-shaped pattern: language gender specificity is high when female MPs are tokens in parliamentary groups with a large preponderance of men; it decreases when their shares start increasing and grows again when they constitute a considerable minority. We argue that this pattern is consistent with the theory of tokenism, and it is produced by the interlinkage of commitment to shared norms and the distribution of “activation thresholds” among female MPs.
In this paper, I argue for Fit, a prudential version of the claim that attitudes must fit their objects, the claim that there is an extra benefit when one's reactions fit their objects. I argue that Fit has surprising and powerful consequences for theories of well-being. Classic versions of the objective list theory, hedonism, desire views, and loving-the-good theories do not accommodate Fit. Suitable modifications change some of the views substantially. Modified views give reactions a robust role as sources of well-being, and they accept that objects call for some attitudes but not others. I argue that objective list theories and loving-the-good theories require the most minimal changes to accommodate Fit, so we have a pro tanto reason to favor these views over alternatives.
Solving a nonsmooth and nonconvex minimization problem can be approached as finding a zero of a set-valued operator. With this perspective, we propose a novel Majorizer–Minimizer technique to find a local minimizer of a nonsmooth and nonconvex function and establish its convergence. Our approach leverages Bregman distances to generalize the classical quadratic regularization. By doing so, we generate a family of regularized problems that encompasses quadratic regularization as a special case. To further demonstrate the effectiveness of our method, we apply it on a lasso regression model, showcasing its performance.
During a pioneering aerial survey of the Near East in the 1920s, Father Antoine Poidebard recorded hundreds of fortified military buildings that traced the eastern frontier of the Roman Empire. Based on their distribution, Poidebard proposed that these forts represented a line of defence against incursions from the east. Utilising declassified images from the CORONA and HEXAGON spy satellite programmes, the authors report on the identification of a further 396 forts widely distributed across the northern Fertile Crescent. The addition of these forts questions Poidebard's defensive frontier thesis and suggests instead that the structures played a role in facilitating the movement of people and goods across the Syrian steppe.
Sufficient vitamin D status is crucial for successful pregnancy and fetal development. The assessment of 25-hydroxyvitamin D (25(OH)D) concentrations is commonly used to evaluate vitamin D status. Our objective was to examine the interrelated biodynamics of maternal and neonatal total, free and bioavailable 25(OH)D in maternal–neonatal dyads at birth and their associations with homeostasis and neonatal birth anthropometry. We analysed a cohort of seventy full-term mother–child pairs. We found positive associations between all neonatal measures of vitamin D status. Maternal forms exhibited a similar pattern of association, except for the bioavailable maternal form. In multivariate analysis, both total and free maternal 25(OH)D concentrations were correlated with all neonatal forms (neonatal total 25(OH)D: 1·29 (95 % CI, 1·12, 1·46) for maternal total 25(OH)D, 10·89 (8·16, 13·63) for maternal free 25(OH)D), (neonatal free 25(OH)D: 0·15 for maternal total 25(OH)D, 1·28 (95 % CI, 0·89, 1·68) for maternal free 25(OH)D) and (0·13 (95 % CI, 0·10, 0·16), 1·06 (95 % CI, 0·68, 1·43) for maternal free 25(OH)D), respectively, with the exclusion of the bioavailable maternal form. We observed no significant interactions within or between groups regarding maternal and neonatal vitamin D parameters and maternal calcium and parathyroid hormone concentrations, and neonatal birth anthropometry. Our study indicates that bioavailable maternal and neonatal 25(OH)D have no significant effects on vitamin D equilibrium, Ca homeostasis and neonatal anthropometry at birth. However, we observed an interaction between maternal and neonatal total and free 25(OH)D concentrations at the maternal–neonatal interface, with no associations observed with other calciotropic or anthropometric outcomes.
Plant-based substitutes (PBS) are seen as a convenient way to transition to a more plant-based diet, but their potential health benefits and nutritional concerns remain debated. Based on a review of the literature, it is concluded here that the primary risk of insufficient nutrient intake with PBS concerns iron and calcium, which are critical to the nutritional value of PBS. Other risks were identified but these would depend on the characteristics of the overall diet, as is the case for iodine in a diet containing no seafood or dairy, and vitamin B12 in a vegetarian/vegan diet. Conversely, the use of PBS is also expected to confer some benefits for long-term health because it would result in higher fibre intakes (in the case of meat PBS) and lower SFA intakes (but higher PUFA/MUFA intakes), but attention should be paid to a potential increase in sodium intake with PBS of meat products. In fact, a recurring finding in this review was that PBS is a very heterogeneous food category involving considerable variations in ingredient and nutrient composition, and whose design could be improved in order to foster nutritional and health benefits. The latter also depend on the animal food that is being replaced and are only deemed likely when PBS replace red meat. The fortification of PBS with key nutrients such as iron and calcium may constitute an actionable public health solution to further shift the balance in favour of PBS in the context of the current dietary transition in western countries.
We study the coupled settling, deformation and mixing dynamics of a dense blob of fluid falling in an axially (vertically) linearly stratified Taylor–Couette cell (operated in a laminar stable regime). This configuration allows the independent analysis of stretching dynamics, driven by radial (horizontal) velocity variations, and settling dynamics, driven by buoyancy forces associated with vertical density variations. As the blob settles, it is stretched in the horizontal plane and forms an elongated lamella. Through the competing effects of transverse compression of the lamella due to this shear-induced stretching and broadening due to diffusion, the lamella irreversibly mixes with ambient fluid, thus progressively adjusting its own density towards that of the ambient fluid. Eventually, the lamella settling stops at a final equilibrium position that depends on the ambient vertical density gradient and the rate at which it has been deformed by the horizontal shear. We show how this final position is determined by stretching-enhanced diffusion, i.e. mixing. We demonstrate that a theoretical mixing model compares favourably with experiments with various Froude numbers (quantifying the relative strength of the horizontal shear and the vertical stratification) and construct a new criterion for the energetic ‘efficiency’ of this mixing process that explicitly captures its inherently diffusive character.
In this essay, I turn to the example of the 1919 Elaine Massacre—the deadliest incident of anti-Black violence in U.S. history—in order to better understand how its economically motivated, state-sanctioned, and brutally indiscriminate violence were nearly erased from history. I find that white journalists, military officials, as well as the Governor of Arkansas himself, drew upon long-standing race-based fears in their characterizations of what took place in Elaine. In so doing, they were able to simultaneously glorify and obfuscate the anti-Black violence, as well as further protect the property and economic interests of the white residents who had putatively been “under threat.” The scale of the violence in Elaine and the near totality of its erasure from the official record make the Elaine Massacre a chilling example of what Lindsay Schakenbach Regele has described as “martial capitalism”: the use of concealed military violence to wrest economic resources away from marginalized communities and toward their white counterparts.
This article investigates the pattern of economic voting at the regional level in Italy. It focuses on the elections held in 18 out of 20 Italian regions from 1995 to 2020. Retrospective voting is examined by using the theory of economic voting, measured at the subnational level. By providing some inferential models and controlling for the impact of phases of recession, this article tests the hypothesis whereby the incumbent regional government is rewarded (or punished) by voters in the event of a good (or poor) state of the regional economy. It mainly considers macroeconomic variables, focusing on the relationship between the unemployment rate (at both national and regional levels) and the electoral performance of the incumbent executive. The empirical analysis shows that, particularly during periods of ‘quiet politics’, economic voting also occurs at the local level and thus the regional unemployment rate affects regional rulers' electoral outcomes.
To advocate for restrictive immigration policies, conservative U.S. politicians have advanced a narrative that Latino immigrants commit violent crimes against White women. This framing of immigrant threat builds on a long history of similar anti-Black discourse and activates racialized ideas about protecting femininity. I demonstrate how the identities of purported victims of immigrant crime connect attitudes about immigration with benevolent sexism—a superficially positive, protective attitude toward particular types of women. An original survey experiment shows that benevolent sexism is activated when victims of immigrant crime are White women. Using nationally representative survey data, I show that the benevolent face of sexism has a notable impact on the immigration attitudes of White Americans, particularly when it comes to the protectionist policy of policing of the U.S.-Mexico border.
A coin always floats in stable equilibrium with its longitudinal axis normal to the air–liquid interface. In contrast, a long thin cylindrical pin floats with its longitudinal axis parallel to the air–liquid interface. In this context, we present a theoretical investigation of the stability of small-scale hydrophobic cylinders floating in vertical and horizontal orientations at various aspect ratios (length/diameter). The study is limited to cylinders denser than water floating at the air–water interface. Our analysis shows that, unlike large-scale vertically floating cylinders, the stability of vertically orientated small-scale cylinders increases with an increase in aspect ratio. A similar trend is observed in the stability of small-scale horizontal cylinders. We also explain the underlying mechanics that leads to a rise in the stability of floating cylinders with an increase in aspect ratio. Unlike large-scale floating cylinders with uniform density, we show that the effect of governing forces (weight, buoyancy and surface tension) in small-scale cylinders changes from a stabilising to a destabilising force with a change in the aspect ratio. For example, in the case of a vertically floating cylinder, the buoyancy force acts as a stabilising force at a small aspect ratio whereas, at large aspect ratios, the buoyancy force has a destabilising influence. Likewise, the body's weight has a destabilising influence at a small aspect ratio and stabilising effect at a large aspect ratio. The reason behind this transformation is that, above a particular aspect ratio, the centre of gravity of small-scale floating cylinders lies below the centre of buoyancy.