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Direct numerical simulations of turbulent flows over highly permeable porous walls were performed at various Reynolds numbers to examine the effects of the Reynolds number on permeable wall turbulence. The porous medium consisted of Kelvin cell arrays with porosity $0.95$, and the permeability Reynolds number $Re_K$ ranged from approximately 7 to 50. Simulations with thin and thick porous walls were performed to investigate the effects of spanwise roller vortices associated with the Kelvin–Helmholtz instability. The results show that the effect of the Kelvin–Helmholtz instability becomes more significant with increasing the permeability Reynolds number, and spanwise rollers, for which length scale is an order of channel height, dominate turbulence when $Re_K \gtrsim 30$. Spanwise rollers reinforce the negative correlation between the wall-normal and streamwise velocity fluctuations close to the porous/fluid interface, and intensify the turbulent velocity fluctuations away from the porous walls, leading to increased frictional resistance. An investigation of the Reynolds number dependence of the modified logarithmic law indicates that the zero-plane displacement and equivalent roughness height are proportional to the square root of permeability, whereas the von Kármán constant increases with the permeability Reynolds number because of the increased mixing length resulting from the relatively large-scale velocity fluctuations induced by spanwise rollers. We developed a model for the modified log law for permeable wall turbulence based on permeability, and confirmed that the skin friction coefficient obtained from the model reasonably predicts the skin friction coefficient for several types of high-porosity porous media. Hence, permeability is a key parameter that characterizes the logarithmic mean velocity profiles over a variety of porous media with high porosity.
For several decades, many efforts have been dedicated to enhancing the accuracy of mortar radiocarbon dating and evaluating the reliability of the results concerning the typology of the examined specimens. Several assumptions that are fundamental for the application of the method may be in many cases not fulfilled, such as (a) complete primary limestone dissociation during calcination, (b) efficient separation of geogenic carbon contained in calcareous aggregates, (c) short carbonation time, and (d) absence of secondary calcite. Many laboratories all over the world have proposed different methods to select suitable fractions of mortar.
The first intercomparison attempt, involving eight international laboratories, was organized in 2016 aiming at comparing and statistically treating the results obtained on the same materials by different laboratories with their own characterization and pre-treatment methods (Hajdas et al. 2017; Hayen et al. 2017). Following this first step, a new intercomparison experiment was proposed and set up in 2018 during the Mortar Dating International Meeting (Bordeaux, FR). A new set of three mortar samples was chosen, taking care of the selection of standardized materials (homogeneity, known mineralogical composition, absence of exogenous inclusions, known expected age).
This work describes the results of two research teams involved in the intercomparison. The samples were characterized, selected, and dated depending on each laboratory strategy. The results stress the importance of the characterization of the raw material is to better understand the mineralogical and petrographical composition of the samples. Such information can support the choice of the most appropriate strategy for the extraction of CO2 and then for data interpretation.
Beneitez et al. (Phys. Rev. Fluids, vol. 8, 2023, L101901) have recently discovered a new linear ‘polymer diffusive instability’ (PDI) in inertialess rectilinear viscoelastic shear flow using the finitely extensible nonlinear elastic constitutive model of Peterlin (FENE-P) when polymer stress diffusion is present. Here, we examine the impact of inertia on the PDI for both plane Couette and plane Poiseuille flows under varying Weissenberg number ${W}$, polymer stress diffusivity $\varepsilon$, solvent-to-total viscosity ratio $\beta$ and Reynolds number ${Re}$, considering the FENE-P and simpler Oldroyd-B constitutive relations. Both the prevalence of the instability in parameter space and the associated growth rates are found to significantly increase with ${Re}$. For instance, as $Re$ increases with $\beta$ fixed, the instability emerges at progressively lower values of $W$ and $\varepsilon$ than in the inertialess limit, and the associated growth rates increase linearly with $Re$ when all other parameters are fixed. For finite $Re$, it is also demonstrated that the Schmidt number $Sc=1/(\varepsilon Re)$ collapses curves of neutral stability obtained across various $Re$ and $\varepsilon$. The observed strengthening of PDI with inertia and the fact that stress diffusion is always present in time-stepping algorithms, either implicitly as part of the scheme or explicitly as a stabilizer, implies that the instability is likely operative in computational work using the popular Oldroyd-B and FENE-P constitutive models. The fundamental question now is whether PDI is physical and observable in experiments, or is instead an artifact of the constitutive models that must be suppressed.
This paper proceeds from a discourse analytical perspective and asks what we can learn from Hebrews 1-2 concerning the relationship of humanity to creation through Christ. First, the exordium is examined to reveal a descent–ascent motif for the incarnate Son who is the one through whom God creates (1:2) and who sustains everything by his powerful word (1:3). The paper then explains how the Son’s sacrificial activity is subsumed within this theology as we look at the catena of scriptural citations found in the rest of chapter 1, where the catena deepens the theology of the exordium by presenting the same events in reverse order. However, towards the end of the catena, when we would expect a reference to the Son and his having inherited a name greater than the angels (1:4), we instead hear about how the angels are sent to serve humanity who inherit salvation. This enables the discourse to move on to chapter 2 and the purpose of Christ’s descent to lead humanity heavenward to glory (2:10). This paper uncovers how that glory is the Son’s own glory and posits a process of theosis by which humanity shares in the Son’s sustaining role over creation.
Tomila Lankina has written a pathbreaking book. Impressively combining theoretical ambition, sensitive attention to historical detail, and the skillful use of multiple quantitative and qualitative methods, The Estate Origins of Democracy in Russia brings the study of Soviet history squarely back onto the agenda of contemporary comparative social science. For those of us who have spent much of our careers trying to explain to academics and policy makers alike why the story of the rise and fall of the USSR still matters for understanding our contemporary world, Lankina’s book is both welcome vindication and a reason for real optimism about the future of social-scientific inquiry. This is, simply put, the best book I’ve read about the Soviet system and its legacies in many years.
Accounts of the factors that led to the drafting of the U.S. Constitutional Convention have focused on Congress' failures to levy taxes, regulate commerce, and provide security against internal unrest and foreign encroachments. Left out from history are the attempts of the founders to force Britain to return thousands of escapees from slavery they sheltered. Patriot state leaders tried to coerce the return of all fugitives from slavery evacuated with the British army by blocking payment of debts to England in violation of the Treaty of Paris. Such actions ultimately caused the breakdown of the agreement and exposed the structural inability of the Congress to enforce the terms of a duly ratified treaty over intransigent states. Ultimately, the issue of the “carried off” and with it the nation's ability to conduct foreign policy, was the paramount issue that could only be resolved by a fundamental restructuring of the federal structure of government.
Deferred prosecution agreements (DPAs) are legal means, alternative to trial, for the resolution of criminal business cases. Although DPAs are increasingly used in the US and are spreading to other jurisdictions, the ethics of DPAs has hardly been subjected to critical scrutiny. We use a multidisciplinary approach straddling the line between philosophy and law to examine the ethics of DPAs used to resolve cases of multinational enterprises’ (MNEs) foreign corruption. Deontologically, we argue that the normativity of DPAs raises critical concerns related to the notion of justice as punishment, with serious cases of international corruption resolved with minimal retribution for offending MNEs. Taking a utilitarian ethical perspective, we also evaluate the effect of DPAs on MNEs’ tendency to self-regulate or re-offend. Our conclusion, supported by critical analysis of the juridical literature and case evidence on MNEs’ recidivism, is that DPAs do not foster ethical behavior.
We prove that the local time of random walks conditioned to stay positive converges to the corresponding local time of three-dimensional Bessel processes by proper scaling. Our proof is based on Tanaka’s pathwise construction for conditioned random walks and the derivation of asymptotics for mixed moments of the local time.
This study assessed the trends in twin births and their survival in Bangladesh by analyzing over a quarter million live births during 1970–2018, pooled from all eight rounds of the Bangladesh Demographic and Health Survey. In these five decades, the twinning rate increased by 1.5 times, from 5.8 to 8.6 twins per 1000 maternities. The decadal twinning rates varied across maternal age, parity, body mass index, household wealth index, and geographic region. The gap in decadal neonatal, infant, and under-five cumulative survival probability between singleton and multiple births was found to be closing, using Kaplan-Meier curves. Child mortality decreased by 80% and 60% in singleton and multiple births respectively. However, the absolute size of child mortality in multiple births remained six times higher than in singletons and was concentrated in the neonatal period. The share of multiple births surged in all types of child mortality. We predict a further and faster rise in multiple births in the coming decades in the face of upward trends in maternal age overlapping with higher parities, education, career prospects, contraceptive use, and the future demand-supply of assisted reproductive technology. A particular focus on the improvement of perinatal and neonatal care with wider availability is warranted. Otherwise, increased multiple births might raise child mortality and create public health challenges.
When bubonic plague arrived in Britain in the mid-14th century, it caused dramatic economic and structural change. Within 50 years, the skill-premium was reduced by half, and another 50 years on, agriculture’s share of the labor force had declined by more than 20 percentage points. This paper develops a two-sector pre-industrial growth model and draws on recent data sources covering Late Medieval and Early Modern Britain to explain these and the ensuing developments. Our main findings are that the skill-premium’s decline was related to the guild and apprenticeship system and that it and the other post-Plague adjustments were crucial determinants of the British trajectory toward industrialization. In particular, prior sectoral transformation and the skill-premium’s determination were important when the Early Modern population boom (1525–1654) threatened to reverse the adjustments caused by the Plague.
Previous studies have revealed an association between dietary factors and atopic dermatitis (AD). To explore whether there was a causal relationship between diet and AD, we performed Mendelian randomisation (MR) analysis. The dataset of twenty-one dietary factors was obtained from UK Biobank. The dataset for AD was obtained from the publicly available FinnGen consortium. The main research method was the inverse-variance weighting method, which was supplemented by MR‒Egger, weighted median and weighted mode. In addition, sensitivity analysis was performed to ensure the accuracy of the results. The study revealed that beef intake (OR = 0·351; 95 % CI 0·145, 0·847; P = 0·020) and white bread intake (OR = 0·141; 95 % CI 0·030, 0·656; P = 0·012) may be protective factors against AD. There were no causal relationships between AD and any other dietary intake factors. Sensitivity analysis showed that our results were reliable, and no heterogeneity or pleiotropy was found. Therefore, we believe that beef intake may be associated with a reduced risk of AD. Although white bread was significant in the IVW analysis, there was large uncertainty in the results given the wide 95 % CI. Other factors were not associated with AD in this study.
Faith, I argue, is a value-oriented perspective, where the subject has a pro-attitude towards the object of the perspective. After summarizing the perspectival account of faith and its upshots that are relevant to the proceeding argument, I give an extended explanatory, cumulative case argument for the account by showing that the perspectival account of faith explains the data that alternative accounts of faith seek to explain, including why faith is present in paradigmatic cases of faith and the truth, or perceived truth, of various statements about faith. In addition, I argue that the perspectival account of faith explains the plausibility of alternative accounts of faith; each of the alternative accounts of faith focuses on a feature or consequence of faith, according to the perspectival account, which we would expect if other faith theorists seek but incorrectly identify the correct account of faith.
When in 1868, Alfred von Kremer (1828–89) in his Geschichte der herrschenden Ideen des Islams (“History of the Ruling Ideas of Islam”) introduced al-Suhrawardī for the first time to a Western readership, he presented him as a freethinking Sufi devoted to “theosophy.” In a long chapter on Sufism, al-Suhrawardī appears under the heading “anti-Islamic tendencies.” Von Kremer characterized al-Suhrawardī's thought as a balanced mixture of three sources: Neoplatonic philosophy, a Zoroastrian theory of light, plus Islamic monotheism. “According to the Arab biographers, his teaching was aimed at the destruction of the existing religion, which, however, they say of anyone who dared to oppose the ruling orthodox party.” Expressing views that openly contradict the ruling religion, von Kremer wrote, meant putting one's life in danger. In accordance with that explanation, al-Suhrawardī died as “a martyr for his convictions” after the all too powerful group of orthodox scholars obtained his death sentence from Saladin.
A new cornulitid genus and species, Porkuniconchus fragilis new genus and species, is here described from the Ärina Formation (Hirnantian, Porkuni Regional Stage) of northern Estonia. This new taxon differs from most cornulitids by having a fusiform ornamentation pattern that is somewhat similar to that of Kolihaia. All studied specimens are attached to a carbonate hardground. The hardground fauna is by abundance and encrustation area dominated by cornulitids. Other encrusters are represented only by a single sheet-like cystoporate bryozoan. The cornulitid specimens represent different growth stages, which suggest that the hardground was continuously colonized by cornulitid larvae. The high encrustation density indicates that the studied hardground may have represented a high-productivity site in the Hirnantian of the Baltic Basin.
In Canada, long-term care and retirement home residents have experienced high rates of COVID-19 infection and death. Early efforts to protect residents included restricting all visitors as well as movement inside homes. These restrictions, however, had significant implications for residents’ health and well-being. Engaging with those most affected by such restrictions can help us to better understand their experiences and address their needs. In this qualitative study, 43 residents of long-term care or retirement homes, family members and staff were interviewed and offered recommendations related to infection control, communication, social contact and connection, care needs, and policy and planning. The recommendations were examined using an ethical framework, providing potential relevance in policy development for public health crises. Our results highlight the harms of movement and visiting restrictions and call for effective, equitable, and transparent measures. The design of long-term care and retirement policies requires ongoing, meaningful engagement with those most affected.