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The dynamics of self-excited shock train oscillations in a back pressured axisymmetric duct was investigated to deepen the understanding of the isolator/combustor coupling in high-speed propulsion systems. The test article consisted of an internal compression inlet followed by a constant area isolator, both having a circular cross-section. A systematic back pressure variation was implemented by using a combination of aerodynamic and physical blockages at the isolator exit. High bandwidth two-dimensional pressure field imaging was performed at $8\,{\rm kHz}$ repetition rate within the isolator for different back pressure settings. The acquisition rate was considerably higher than the dominant frequency of the shock train oscillations across the different back pressure settings. The power spectral density of the pressure fluctuations beneath the leading shock foot exhibited broadband low frequency oscillations across all back pressures that resembled the motions of canonical shock–boundary layer interaction units. A node in the vicinity of reattachment location that originated the pressure perturbations within the separation shock was also identified, which further ascertained that the leading shock low frequency motions were driven by the separation bubble pulsations. Above a threshold back pressure, additional peaks appeared at distinct higher frequencies that resembled the acoustic modes within the duct. However, none of the earlier expressions of the resonance acoustic frequency within a straight duct agreed with the experimentally observed value. Cross-spectral analyses suggested that these modes were caused by the shock interactions with upstream propagating acoustic waves that emanate from the reattachment location, originally proposed for transonic diffusers by Robinet & Casalis (2001) Phys.Fluids13, 1047–1059. Feedback interactions described using one-dimensional stability analysis of the shock perturbations by obliquely travelling acoustic waves (Robinet & Casalis 2001 Phys.Fluids13, 1047–1059) made favourable comparisons on the back pressure threshold that emanated the acoustic modes as well as the acoustic mode frequencies.
Care theorists have had enough. Decades of neoliberalism, followed by financial crisis, austerity, gender backlash, and, in 2020, a worldwide infectious disease pandemic, have clearly tested their patience. The titles alone of three recent books on the ethics and politics of care suggest a change in tone; indeed, “radical,” “revolutionary,” and “manifesto” are generally not words we associate with the scholarship of those interested in the everyday practices of responding to the needs of others. And yet for Maurice Hamington, Lynne Segal, and co-authors Jennifer Nedelsky and Tom Malleson, these quotidian practices, and the ethos that underlies them, are more radical than they seem. Indeed, these volumes suggest that a commitment to care—a commitment that is both ideational/ethical and material—is necessary to usher in the kind of politics we so desperately need today. It could be, then, that with their latest books, these authors are edifying and formalizing what we might call the “radical turn” in research on care—a turn that can be roughly said to have begun in 2020 with the Care Collective’s The Care Manifesto (Verso) and the parallel Care Manifesto (Femnet) written by and for women of Africa, Asia, and Latin America a year later.
Over the past two decades, political science has produced varied examples of ethnographic approaches. These approaches have not only tackled epistemological dilemmas but also exposed a second methodological dimension of ethnographic practice that is not so systematically explored: the relationship of researchers to their research participants. In this article, we focus on this second dimension, using emblematic texts in political science, especially in comparative politics, to develop a fourfold typology of political ethnographies that takes into account the emotional dynamics between researchers and participants. We use this typology to analyze various gradations through which these emotional dynamics develop in fieldwork. Focusing on the navigation between distance and proximity that these dynamics entail, we propose the concept of “emotional proximity” to capture relations between the researcher and the participant. We investigate the validity of this novel typology by applying it to ethnographic studies of far-right actors. The political distance separating researchers and participants in these studies allows us to investigate the methodologies of disconnecting political from emotional dynamics across this fourfold schema of ethnographic varieties. We argue that the “infidelity” of emotional distance (instead of proximity) is not an objectivist epistemological necessity but a methodological tool that is indispensable to the practice of participant observation.
In natural speech, phonetic cues that distinguish lexical items can be hyperarticulated when there is a minimal pair competitor, a process known as contrastive hyperarticulation. Building upon prior work, this article examines the cue-specific nature of contrastive hyperarticulation in Japanese, focussing on stop voice onset time (VOT) using a speech corpus. We confirmed that the existence of a voicing minimal pair competitor in the lexicon triggers hyperarticulation of VOT duration on the target segment (shorter for voiced stops and longer for voiceless stops), while other contrasts (singleton vs. geminate) did not. The results also suggest that contrastive hyperarticulation (a) is more compatible with casual speech than slow/clear speech, (b) is sensitive to position in a word (greater in word-initial position than in non-initial position) and (c) applies to a greater degree in Japanese than in English due to properties of stops. This provides further evidence that the phonetic specificity of contrastive hyperarticulation is cross-linguistically relevant.
In this paper, we generalise to the family of Fermat quartics $X^4 + Y^4 = 2^m, m \in \mathbb {Z}$, a result of Aigner [‘Über die Möglichkeit von $x^4 + y^4 = z^4$ in quadratischen Körpern’, Jahresber. Deutsch. Math.-Ver.43 (1934), 226–228], which proves that there is only one quadratic field, namely $\mathbb {Q}(\sqrt {-7})$, that contains solutions to the Fermat quartic $X^4 + Y^4 = 1$. The $m \equiv 0 \pmod 4$ case is due to Aigner. The $m \equiv 2 \pmod 4$ case follows from a result of Emory [‘The Diophantine equation $X^4 + Y^4 = D^2Z^4$ in quadratic fields’, Integers12 (2012), Article no. A65, 8 pages]. This paper focuses on the two cases $m \equiv 1, 3 \pmod 4$, classifying for $m \equiv 1 \pmod 4$ the infinitely many quadratic number fields that contain solutions, and proving for $m \equiv 3 \pmod 4$ that $\mathbb {Q}(\sqrt {2})$ and $\mathbb {Q}(\sqrt {-2})$ are the only quadratic number fields that contain solutions.
Meaning-making in psychotic experiences may affect mental health recovery by influencing the degree to which a person experiences Meaning in Life (MIL). However, how meaning made in such experiences impacts MIL is poorly understood. We aimed to explore how service users engage in meaning-making in their experience of a first-episode psychosis (FEP) (as well as subsequent and current psychotic experiences), and to identify if and how this meaning has influenced their current perspective on MIL.
Methods:
The study aim was addressed using Interpretative Phenomenological Analysis (IPA). We used purposive maximum variation sampling and conducted semi-structured interviews with 16 members of an epidemiologically complete FEP incidence cohort in the Republic of Ireland. Data analysis was guided by IPA procedures.
Results:
We found psychotic experiences both contributed to and eroded MIL but also created memory blanks, blocking the process of meaning-making. Meaning-making in psychotic experiences involved: Living with the impact of psychosis on the self and identity (Survival); Reconnecting with time to move forward in time (Restoring temporality); Navigating agency and powerlessness in chaos (Reclaiming control); Generating Meaning in Life in a vacuum (Presence in absence); and Trying to find a home for psychosis or not needing to (Narrative re-storying).
Conclusions:
Findings challenge current meaning-making theory; suggesting that it may not be fully applicable to the lives of people experiencing psychosis. Our data also have implications for the implementation of trauma informed care, the recovery approach in mental health, clinical practice, and research.
In recent years, integrating physical constraints within deep neural networks has emerged as an effective approach for expediting direct numerical simulations in two-phase flow. This paper introduces physics-informed neural networks (PINNs) that utilise the phase-field method to model three-dimensional two-phase flows. We present a fully connected neural network architecture with residual blocks and spatial parallel training using the overlapping domain decomposition method across multiple graphics processing units to enhance the accuracy and computational efficiency of PINNs for the phase-field method (PF-PINNs). The proposed PINNs framework is applied to a bubble rising scenario in a three-dimensional infinite water tank to quantitatively assess the performance of PF-PINNs. Furthermore, the computational cost and parallel efficiency of the proposed method was evaluated, demonstrating its potential for widespread application in complex training environments.
This article examines the reception of Sappho in Julius Pollux’s Onomasticon. The article shows that Pollux primarily quotes Sappho as an authoritative source on clothing and textiles. This presentation of Sappho is unusual, given that other ancient sources largely locate her poetry within an erotic, and sometimes sympotic, framework; and it is particularly notable for the way in which it emphasizes Sappho’s status as a specifically female poet with special insight into, and expertise in, the feminine domestic world. The article argues that this domestication of Sappho’s verses is not (primarily) an act of sexist belittlement, but rather demonstrates how Pollux reimagines Sappho in his own image. In the material world of the Onomasticon, Sappho becomes in turn an emblem of (feminine) materiality, whose apparent preoccupation with the fabric of everyday life productively mirrors the encyclopaedia’s own. As a whole, the article argues that Pollux’s creative engagement with Sappho’s poetry is both an important constituent part of, and a foil to, her wider reception in both antiquity and modernity.
Numerical studies on the statistical properties of irregular waves in finite depth have to date been based on models founded on weak nonlinearity; as a consequence, only lower-order (usually third-order) nonlinear interactions have thus far been investigated. The present study performs numerical simulations with a fully nonlinear, spectrally accurate model to investigate the statistics of irregular, unidirectional wave fields in finite water depth initially given by a Texel, Marsen and Arsloe spectrum. A series of random unidirectional wave fields are considered, covering a wide range of water depth. The wave spectrum and statistical properties, including the probability density function of the surface elevation, exceedance probability of wave crests and occurrence probability of extreme (rogue) waves, are investigated. The importance of full nonlinearity in comparison with third-order results is likewise evaluated. The results show that full nonlinearity increases kurtosis and enhances the occurrence probability of large wave crests and rogue waves substantially, in both deep water and finite water depth. Therefore, we propose that full nonlinearity may contribute significantly to the formation of rogue waves. Furthermore, to account for the effects of higher-order nonlinearity on modulational instability, we analyse the relationship between the Benjamin–Feir index (BFI) and maximal excess kurtosis. Our results show a strong linear relationship i.e. $({\mathcal{K}}_{max}-3)\propto {\textrm{BFI}}$, in contrast to $({\mathcal{K}}_{max}-3)\propto {\textrm{BFI}}^2$ based on the assumptions of weak nonlinearity, a narrow-banded spectrum and deep-water conditions. Above, $\mathcal{K}_{max}$ is the maximal kurtosis.
The Avicennan text De congelatione et conglutinatione lapidum had a great influence on the alchemical thought of the thirteenth century. This Latin text disputed both the veracity of alchemy and the possibility of alchemical transmutation by arguing that art is inferior to nature and that the alchemists cannot manipulate a metal because its true characteristics are hidden from our senses; thus an alchemist cannot change something which is unknown to him. Newman’s pioneer studies examined the diffusion and impact of the first Avicennan argument on medieval alchemy and he shed light on the art-versus-nature debate. This paper has a twofold aim: on the one hand it aims to further Newman’s study by focusing on the second Avicennan argument, which is closely related to the problem of substantial form, and on the other hand it aims to show how the aforesaid problem paved the way for the emergence of corpuscularianism, which flourished during the early modern period. In this regard, it will become clear that the historiographical case of alchemy and its problem of substantial form can serve as an exegetical tool for ‘bridging’ the Middle Ages and the early modern period with respect to the relation between Aristotelianism and corpuscularianism.
In the American Southwest and northern Mexico, it has long been argued that ceramic vessels with exterior surfaces that are covered with small nodes are Datura seed pod effigies. Datura is a genus of flowering plants containing psychoactive alkaloids that, when consumed, can induce hallucinations. Scholars have argued that these noded vessels were part of a ritual complex originating in Mexico and spreading throughout the Southwest. In his 2012 article, Lankford hypothesized that this ritual complex made its way into the southeastern United States based on the presence of the ceramic type Fortune Noded in the Mississippi River Valley. In this article, we evaluate three hypotheses suggested by Lankford. Our absorbed residue study did not support his first hypothesis that Fortune Noded vessels were directly related to Datura consumption. However, existing archaeological data do support the idea that a ritual complex including noded vessels moved through the Caddoan region to the Central Mississippi Valley. Those data also confirm Lankford’s final hypothesis that Datura was used in Mississippian period contexts in the Central Mississippi Valley. We conclude that Lankford’s hypothesis has merit and suggest that noded vessels and other ritual equipment be considered inalienable objects that moved through a network of ritual practitioners.
In many developing countries, law students face challenges in accessing authoritative legal resources, including statutes, case law, and journal articles, due to the high costs of subscription-based databases such as LexisNexis, HeinOnline, and Westlaw. In Nigeria, additional subscription online resources are available, including LawPavilion, Legalpedia, and Compulaw. These platforms are all rich in content and currency; however, they are often unaffordable for both law students and law libraries. To overcome these challenges, there are many initiatives and movements administered by government institutions, universities, and non-governmental organizations (NGOs) that provide access to both primary and secondary sources of law. Included in the latter group are the Legal Information Institutes (LIIs), Google Scholar, the Social Science Research Network (SSRN), and Justia. This paper examines the role of free legal databases as an alternative for law students and how these freely accessible platforms can support the access gaps that subscription-based legal research tools have often created. The study is conceptual in nature, with reliance on existing literature and analysis of freely available legal information resources to support legal education.
In this article, which has a strong methodological focus, we establish the labour relations that characterized the urban population of the Swedish town of Västerås in 1820. Several sources are combined: the so-called Tabellverket (an early form of demographic statistics) and observations made in, primarily, local court records. To assign labour relations as defined by the Global Collaboratory on the History of Labour Relations project, the preliminary picture based on the Tabellverket is complemented by systematically adding information from court records analysed in the Gender and Work project. This information captures both what people did and also, to some extent, what labour relations they were involved in. Subsequently, all the information is collated to estimate the labour relations characterizing the whole population in the selected town. The result of this experiment is a much more encompassing and richer picture of the labour relations within the selected community, one that acknowledges both women’s work and multiple employments. In a broader perspective, the case study contributes to our understanding of the gradual increase of commodified labour in the world.
The opening of Book 4 of Valerius Flaccus’ Argonautica finds its protagonists confounded by the loss of Hercules, their hero-of-heroes whom Juno has caused to run off. As the Argonauts deliberate, loyalty to the man contends with the desire to carry on his heroic labor, presented in terms of Vergilian arma uirumque. This paper uses the debate over Hercules’ abandonment as a case study for Valerius’ engagement with Vergil’s celebration of the fides, pietas and magnanimitas of his hero as the foundation of Roman political legitimacy. By setting Valerius’ Vergilian framing in dialogue with his engagement with Lucan’s Bellum Ciuile and Horace’s Epodes, I argue that the Argonautica rereads Aeneas’ exemplary model as a guide to internecine conflict, exploring how the essential Augustan concepts of duty and familial fidelity may be encoded and reproduced to a very different effect.