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The influence of surface roughness on transition to turbulence in a Mach 4.5 boundary layer is studied using direct numerical simulations. Transition is initiated by the nonlinearly most dangerous inflow disturbance, which causes the earliest possible breakdown on a flat plate for the prescribed inflow energy and Mach number. This disturbance primarily comprises two normal second-mode instability waves and an oblique first mode. When localized roughness is introduced, its shape and location relative to the synchronization points of the inflow waves are confirmed to have a clear impact on the amplification of the second-mode instabilities. The change in modal amplification coincides with the change in the height of the near-wall region where the instability wave speed is supersonic relative to the mean flow; the net effect of a protruding roughness is destabilizing when placed upstream of the synchronization point and stabilizing when placed downstream. Assessment of the effect of the roughness location is followed by an optimization of the roughness height, abruptness and width with the objective of achieving maximum transition delay. The optimization is performed using an ensemble-variational (EnVar) approach, while the location of the roughness is fixed upstream of the synchronization points of the two second-mode waves. The optimal roughness disrupts the phase of the near-wall pressure waves, suppresses the amplification of the primary instability waves and mitigates the nonlinear interactions that lead to breakdown to turbulence. The outcome is a sustained non-turbulent flow throughout the computational domain.
Recent developmental state research highlights state-society configurations and contentious politics in shaping industrialization. Still, much of this work focuses on East Asia and tends to sidestep racialized labor exploitation, imperialism, and uneven incorporation into the global capitalist system through the trans-Atlantic slave trade and colonialism as important drivers. Through an historical analysis of Trinidad and Tobago, this paper examines how interventionist industrial policies emerged out of such structures and conditions. It highlights the role of anti-imperial and anti-racist struggles exemplified by the Black Power Movement in Trinidad and Tobago – a social movement comprising workers, marginalized youth, and civic leaders, which sought to overturn a colonial economy, reconfigure hierarchical race relations, address economic injustices, promote democratically negotiated industrialization, and chart a new course for a post-independent, multiracial Trinidad and Tobago. Utilizing archival data, this paper argues that Trinidad and Tobago’s government shifted from a passive industrial strategy characteristic of the colonial era to a more active approach from 1970 to 1984 largely in response to forceful demands and demonstrations by the Black Power Movement, which, in turn, led to improved social conditions, nationalization of key industries, the creation of state-owned enterprises, new skills and technological investments, and more. These findings advance developmental state theory by specifying the heretofore largely unacknowledged role of racial justice and anti-imperialist social movements in bringing about a different path from the East Asian model toward industrial and social transformation.
In the last two decades, the Chinese government has made serious attempts to enhance social provision by contracting out social services. Empirical evidence suggests that openness and flexibility of resource allocation gradually decrease from Guangzhou in southern China to Beijing in northern China, amongst China’s three first-tier cities. This study further reveals that state–non-governmental organisation (NGO) relations vary not only across geographical locations but also amongst service sectors governed by government departments and mass organisations. The varied state–NGO relations across geographical locations and service sectors manifest the complexity of the state–NGO collaboration under China’s fragmented authoritarian governance system. Different local circumstances and diverse considerations of local officials involving vertical and horizontal lines of authority accounted for the variations and complexity from the eyes of NGO practitioners.
In the Global North, mass warfare created a huge demand for social protection, pushing governments to provide income for invalids, war victims, and the survivors of fallen soldiers. Most European colonial powers, including France and Great Britain, recruited soldiers and other security forces not only from their metropoles but also from their colonies during both World Wars. However, the question of how mass warfare influenced social reforms in former colonies has not been systematically addressed, particularly with respect to how these influences varied across colonial powers. To begin to address this gap, this paper explores the warfare–welfare nexus in the context of British and French colonies of West Africa around World War I (WWI). The paper finds that, while Britain and France had similar overarching imperial and military objectives in West Africa of securing their colonies, enforcing order within them, and promoting commerce to increase profit, they went about achieving them very differently, with direct and indirect implications for social reforms after WWI. While only a first step, research on the distinct nature of the warfare–welfare nexus in colonial contexts is critical in order to historicize and close research gaps by widening and deepening our understanding of social policy trajectories in countries of the Global South.
Arazyme, an alkaline metalloprotease, is produced by Serratia proteamaculans, a symbiotic bacterium isolated from the intestinal ecosystem of Nephila clavata. Arazyme is known to play a crucial role in facilitating the digestion process in N. clavata. Recently, there has been increasing interest in exploring invertebrate-associated gut symbionts as a valuable source of novel and biologically active enzymes. Animal husbandry has shown significant interest in this spider-derived bioactive enzyme. This paper aims to provide a comprehensive review of the current understanding and knowledge of arazyme in the context of animal husbandry, offering valuable references for potential applications of this enzyme.
The distinction between ‘Singapore English’ and ‘Singaporean English’ is interesting. It appears that small places tend to use the bare name of the country, while larger countries use the derived adjective. So we find: Singapore English, Hong Kong English, Brunei English; but American English, German English, Malaysian English. On this basis, we might favour Chinese English over China English, because China is big.
There is a pressing need for studies of large sample sizes and variable age ranges to delineate the mechanism underlying reduced visual attention to biological motion in autism. Here we focused on the basic movement of the eyes or mouth in guiding attention. The stimuli face blinked continuously or moved the mouth silently. In a large sample (145 autistic and 132 non-autistic participants) ranging from 3 to 17 years old, we assessed whether autistic participants showed reduced visual attention to basic movement of the eyes or mouth using a free-viewing eye-tracking task. We found that, like non-autistic participants, autistic participants increased their eye-looking time when viewing the blinking face and increased mouth-looking time when viewing the mouth-moving face. Furthermore, these effects were stable across ages, suggesting the presence of a developmentally stable attentional capture by basic face movements in both groups. We also found that autistic participants looked less at basic face movement than non-autistic participants. Our results suggest that autistic children and adolescents could modulate their visual attention to the basic face movements, but their modulation effect is weaker than non-autistic participants. These results further our understanding of the mechanism underlying visual attention-to-face movement in autistic people.
The trade of intermediates now accounts for a growing share of global trade. In this highly fragmented global production system, any change in tariff rates can generate a higher impact than that of initial direct tariffs. To assess the impact of tariffs on global value chain participation, this study uses value-added trade statistics and cumulative tariff rates for 12 sectors from 168 countries for the years 1990–2015. The visual inspection suggests that initial tariffs result in higher tariff rates (almost 14%) due to a knock-on impact along with supply chains. The main empirical finding is that both faced and imposed tariff rates have significant negative impacts on sectoral global value chain participation. The effect is also persistent in the analysis if we employ cumulative tariff rates. Apart from these policy determinants, sector- and country-level endowments, such as higher relative length, capital intensity, foreign direct investment stock, and human capital appear to be the major drivers for higher total, forward, and backward global value chains participation. Even if our main results are robust, there are also some distinctions in the effects of tariff rates depending on the country- and sector-level heterogeneities. In a policy-related debate, given the cascading impacts of these liberalization initiatives, autonomous, regional, and global liberalization efforts are critical for all sectors to reap the benefits from the global production system.
The aim of this paper is to contribute to debate on Hegel's conception of the relationship between religion and philosophy by proposing that it can be a read as a division of labour between Christian religion and speculative philosophy. This reading allows us to understand better Hegel's idea that religion and philosophy have the same content in two different forms. I distinguish between the institutional and the intrapersonal dimensions of Hegel's claim of a division of labour between religion and philosophy. I then turn to a critique of Hegel's philosophy of religion by showing how David Friedrich Strauss's concluding dissertation from The Life of Jesus, Critically Examined can call our attention to some internal tensions within Hegel's conception. Although Strauss's interpretation does not present an insurmountable objection against Hegel's conception of a division of labour, it can help to illuminate to what extent Hegel oversimplified the practical implications that his conception might have for the priest's attempt to continue his instruction to the members of his community.
There is currently disagreement in the international sports world about whether Russian and Belarusian athletes should be admitted to international competitions. While initially proposing to ban these athletes, the International Olympic Committee (IOC) is now recommending that sports federations readmit Russian and Belarusian athletes under certain conditions. The IOC believes that this is unavoidable in order to respect human rights. Sports federations are invoking their autonomy on this issue, with some following the IOC’s advice, some maintaining a ban, and others allowing unconditional participation. This piece seeks to correct the IOC’s interpretation of the applicable human rights standard. It asserts that sporting bodies must respect human rights, and that the principles of autonomy and neutrality of sport must be considered in light of internationally recognised human rights standards. If these are used as a yardstick, it becomes clear that collective exclusion can be justified in the extreme case of a war of aggression.
Recently there has been a revival of interest in both the historical and archaeological dimensions of the destruction of cities. The destruction of the principal settlement of a polis is one thing, the effective eradication of the political community quite another. What did it take to destroy a political community? The historical record is full of references to destructions of one polis by another in late Classical to Hellenistic times in Crete. And though not all of these destructions led to the end of the political community in question, some did, and between the Classical period (where we know of 49 poleis) and the Roman conquest of Metellus (where we know of only 24) the numbers of Cretan poleis were drastically reduced. The destruction of Praisos by Hierapytna between 145 and 140 BC (Strabo 10.4.12) was one such case. This seems to form part of a horizon of destructions (of Dreros, Apollonia and Phaistos) that took place between 200 and 140 BC. Florence Gaignerot-Driessen has demonstrated that there is a clear ritual dimension to this in the case of Dreros, a dimension indicated elsewhere by the use of the verb κατέσκαψαν. Excavations at Praisos have shed light on this question. This paper argues that, while there is no evidence for a widespread destruction by fire, there is clear evidence for the ending of Praisian sanctuaries and the forced abandonment of houses and (most intriguingly) the abandonment of large storage vessels. A particular archaeological ‘signature’ of these abandonments, evident at Dreros, Phaistos and Praisos, is the abandonment of the ‘household pithos’, which in many cases seem to be older than the houses in which they have been found. The paper also argues that these archaeological signatures of what had to be destroyed in order to eradicate a political community in turn shed light on what made this particular form of ‘citizen state’ so resilient.
We propose a modification to the random destruction of graphs: given a finite network with a distinguished set of sources and targets, remove (cut) vertices at random, discarding components that do not contain a source node. We investigate the number of cuts required until all targets are removed, and the size of the remaining graph. This model interpolates between the random cutting model going back to Meir and Moon (J. Austral. Math. Soc.11, 1970) and site percolation. We prove several general results, including that the size of the remaining graph is a tight family of random variables for compatible sequences of expander-type graphs, and determine limiting distributions for binary caterpillar trees and complete binary trees.
The formation process of the leading vortex ring in starting jets with uniform background co- and counter-flow has been studied numerically for $-0.5\leq R_v\leq 0.5$, where $R_v$ is the ratio of background velocity to jet velocity. For the cases with background counter-flow, the normal formation process of the leading vortex ring would be destroyed when $R_v<-0.4$, i.e. the trailing jet would overtake the leading vortex ring through the centre, a phenomenon reminiscent of vortex leapfrogging. As the velocity ratio $R_v$ increases, the formation number $F_{t^*}$ decreases from $9.6$ at $R_v=-0.4$ to $1.92$ at $R_v=0.5$. An analytical model based on the kinematic criterion has been developed so as to describe the relationship between the formation number $F_{t^*}$ and velocity ratio $R_v$. A linear relationship between the vortex core parameter and stroke ratio of starting jet ($\varepsilon \sim k_1L/D$) for the Norbury vortex ring has been established and used effectively to close the model. For co-flow with $0< R_v\leq 0.5$, the results from this model are consistent with the present numerical simulation and the experiments by Krueger et al. (J. Fluid Mech., vol. 556, 2006, pp. 147–166). For counter-flow, two different equations are proposed for $-0.4\leq R_v\leq -0.2$ and $-0.2< R_v<0$, respectively.
We consider parallel single-server queues in heavy traffic with randomly split Hawkes arrival processes. The service times are assumed to be independent and identically distributed (i.i.d.) in each queue and are independent in different queues. In the critically loaded regime at each queue, it is shown that the diffusion-scaled queueing and workload processes converge to a multidimensional reflected Brownian motion in the non-negative orthant with orthonormal reflections. For the model with abandonment, we also show that the corresponding limit is a multidimensional reflected Ornstein–Uhlenbeck diffusion in the non-negative orthant.
This article presents the results of a preliminary bioarchaeological study of 10 funerary urns containing human burned remains from the Los Tamarindos urn-field cemetery dated to the Postclassic period. I was able to determine the basic biological profile data. In addition, I determined the fragmentation rate as well as the thermal alternation of bones from funerary urns from Los Tamarindos, which allowed me to propose the first observations about the Pretarascan cremation burial practices in this region. The low weight of bones indicates that burials should be determined as partial burials; however, they contain fragments of bones from each anatomical region. The structure of the bones and the chromatic discoloration caused by the thermal alternation indicate that temperature during the cremation did not exceed 900°C, given that the cremains did not exhibit the recrystallization structure, which is interpreted as a characteristic feature of the high maximum temperature of a funerary pyre during the cremation.
After their ejection from the Church of England, it is said that the English Presbyterians split into two factions. The ‘Dons’, led by Richard Baxter, pursued comprehension and reunion with the national Church, whilst the ‘Ducklings’ petitioned for an indulgence of their separation. In this article, it is argued that this twofold distinction is largely false. Rather, all English Presbyterians sought unity; their divergence in terms of practical policy stemmed from subtly different conceptions of catholicity. Thus, paradoxically, indulgence came to be seen as a pathway towards comprehension. Conventicle preaching, meanwhile, became a curious form of curacy, operating in tandem with the parish ministry.