To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The effect of a counter-current gas flow on the linear stability of an inclined falling liquid film switches from destabilizing to stabilizing, as the flow confinement is increased. We confront this linear effect with the response of nonlinear surface waves resulting from long-wave interfacial instability. For the strongest confinement studied, the gas flow damps both the linear growth rate and the amplitude of nonlinear travelling waves, and this holds for waves of the most-amplified frequency and for low-frequency solitary waves. In the latter case, waves are shaped into elongated humps with a flat top that resist secondary instabilities. For intermediate confinement, the linear and nonlinear responses are opposed and can be non-monotonic. The linear growth rate of the most-amplified waves first decreases and then increases as the gas velocity is increased, whereas their nonlinear amplitude is first amplified and then damped. Conversely, solitary waves are amplified linearly but damped nonlinearly. For the weakest confinement, solitary waves are prone to two secondary instability modes that are not observed in unconfined falling films. The first involves waves of diminishing amplitude slipstreaming towards their growing leading neighbours. The second causes wave splitting events that lead to a train of smaller, shorter waves.
We study the three-dimensional structure of turbulent velocity fields around extreme events of local energy transfer in the dissipative range. Velocity fields are measured by tomographic particle velocimetry at the centre of a von Kármán flow with resolution reaching the Kolmogorov scale. The characterization is performed through both direct observation and an analysis of the velocity gradient tensor invariants at the extremes. The conditional average of local energy transfer on the second and third invariants seems to be the largest in the sheet zone, but the most extreme events of local energy transfer mostly correspond to the vortex stretching topology. The direct observation of the velocity fields allows for identification of three different structures: the screw and roll vortices, and the U-turn. They may correspond to a single structure seen at different times or in different frames of reference. The extreme events of local energy transfer come along with large velocity and vorticity norms, and the structure of the vorticity field around these events agrees with previous observations of numerical works at similar Reynolds numbers.
We have conducted an extensive study of the scaling properties of small scale turbulence using both numerical and experimental data of a flow in the same von Kármán geometry. We have computed the wavelet structure functions, and the structure functions of the vortical part of the flow and of the local energy transfers. We find that the latter obey a generalized extended scaling, similar to that already observed for the wavelet structure functions. We compute the multi-fractal spectra of all the structure functions and show that they all coincide with each other, providing a local refined hypothesis. We find that both areas of strong vorticity and strong local energy transfer are highly intermittent and are correlated. For most cases, the location of local maximum of the energy transfer is shifted with respect to the location of local maximum of the vorticity. We, however, observe a much stronger correlation between vorticity and local energy transfer in the shear layer, that may be an indication of a self-similar quasi-singular structure that may dominate the scaling properties of large order structure functions.
Despite the ample database of research findings on the benefits of Processing Instruction (PI), research thus has primarily made use of offline measures to establish how L2 learners comprehend and process sentences. Using online methodology, such as eye-tracking, allows research to more directly measure implicit knowledge. The sensitivity of these measures requires meticulous design choices to ensure validity and replicability. This study provides an overview of the linguistic and physical design considerations necessary for creating eye-tracking materials in SLA research. The present study demonstrates the application of these design considerations in an eye-tracking study, comparing the changes in processing patterns between two types of instruction: PI and Traditional Instruction (TI) on low intermediate L2 adult learners’ acquisition of the French imperfect aspect. The results of the experimental study show beneficial gains made by L2 learners who received PI on the French imperfect tense, this was seen in both a significant increase in accuracy scores from pre-test to post-test and change in their cognitive processing as shown by eye-movement data. The present study emphasizes the need for future studies to consider methodological reflections and key design principles in eye-tracking research.
Impairments in self-recognition (i.e. recognition of own thoughts and actions) have been repeatedly shown in individuals with schizophrenia. According to classical clinical characterizations, schizophrenia is included in a continuum encompassing a large range of genetic statuses, psychotic states and symptoms. The current meta-analysis aims to determine whether self-recognition is affected by individuals within the psychosis continuum.
Three populations were considered: people with an at-risk mental state for psychosis (ARMS), hallucination-prone individuals and unaffected relatives of patients with schizophrenia. Eleven studies contrasted self-recognition between these three populations (n = 386) and healthy controls (n = 315) and four studies used correlational analysis to estimate comparable effects (n = 629). Eligible studies used experimental paradigms including source-monitoring and self-monitoring.
We observed significantly reduced self-recognition accuracy in these populations [g = −0.44 (−0.71 to −0.17), p = 0.002] compared to controls. No influence of the type of population, experimental paradigm or study design was observed.
The present analysis argues for self-recognition deficits in populations with no full-blown psychotic symptoms represented across the continuum of psychosis.
Based on the observed clinical overlap between obsessive–compulsive disorder (OCD) and schizophrenia (SCZ), both conditions may share, at least in part, common cognitive underpinnings. Among the cognitive deficits that could be involved, it has been hypothesized that patients share a failure in their abilities to monitor their own thoughts (source monitoring), leading to confusion between what they actually did or perceived and what they imagined. Although little is known regarding source-monitoring performances in patients with OCD, numerous studies in patients with SCZ have observed a relationship between delusions and/or hallucinations and deficits in both internal source- and reality-monitoring abilities.
The present work compared source-monitoring performances (internal source and reality monitoring) between patients with OCD (n = 32), patients with SCZ (n = 38), and healthy controls (HC; n = 29).
We observed that patients with OCD and patients with SCZ displayed abnormal internal source-monitoring abilities compared to HC. Only patients with SCZ displayed abnormalities in reality monitoring compared to both patients with OCD and HC.
Internal source-monitoring deficits are shared by patients with OCD and SCZ and may contribute to the shared cognitive deficits that lead to obsessions and delusions. In contrast, reality-monitoring performance seems to differentiate patients with OCD from patients with SCZ.
We study a gravity-driven wavy liquid film falling down the inner surface of a narrow cylindrical tube in the presence of an active core gas flow. We employ the model of Dietze and Ruyer-Quil (J. Fluid Mech., vol. 762, 2015, pp. 68–109) to investigate the role of surface waves in the occlusion of the tube. We consider four real working liquids and reproduce several experiments from the literature, focusing on conditions where the Bond number is greater or equal to unity. We prove that occlusion is triggered by spatially growing surface waves beyond the limit of saturated travelling-wave solutions, and delimit three possible regimes for a naturally evolving wavy film: (i) certain occlusion, when the liquid Reynolds number is greater than the limit of the spatially most amplified travelling waves. Occlusion is caused by surface waves emerging from linear wave selection (scenario I); (ii) conditional occlusion, when the most amplified waves possess travelling states but longer waves do not. Occlusion is triggered by secondary instability, generating long waves through nonlinear coarsening dynamics (scenario II); and (iii) impossible occlusion, when travelling waves always exist, no matter how great their wavelength. We show that certain occlusion is delayed by gravity and precipitated by a counter-current gas flow, axial viscous diffusion (high-viscosity liquids) and inertia (low-viscosity liquids). The latter two effects are also found to determine whether the occlusion mechanism is dictated by loss of travelling-wave solutions or absolute instability. Finally, we show that occlusion can be prevented through coherent inlet forcing. As a side benefit, we introduce an augmented version of our model based on a localized additional force term that allows representing stable travelling liquid pseudo-plugs.
Over recent decades there has been considerable mental health research in Sierra Leone but little on local conceptualisations of mental health conditions. Understanding these is crucial both for identifying the experienced needs of the population and utilising relevant community-based resources to address them. This study took a grounded approach to identify the ways in which adults in Sierra Leone express psychological distress.
Rapid ethnographic methods deployed included 75 case study interviews with community members, 12 key informant (KI) pile sorts and 55 KI interviews. Thematic analysis of data was supported by frequency analysis and multi-dimensional scaling.
Thirty signs of distress were identified. The only consistent ‘syndrome’ identified with respect to these was a general concept of crase, which referred to psychosis-related presentation but also a wide range of other signs of distress. We did not find consensus on locally defined concepts for mild-moderate forms of mental disorder: people use multiple overlapping signs and terms indicating psychological distress.
Analysis supports calls to view mental health problems as a ‘continuum of distress’ rather than as discrete categories. This framing is coherent with opportunities for prevention and response in Sierra Leone which do not focus primarily on formal healthcare service providers but rather involve a range of community-based actors. It also enables attention to be paid to the identification of milder signs of distress with a view to early response and prevention of more severe mental health problems.
The presence of visual hallucinations in addition to auditory hallucinations (V + AH) is associated with poor prognosis in patients with schizophrenia. However, little consideration has been given to these symptoms and their underlying cognitive bases remain unclear. Based on cognitive models of hallucinations, we hypothesized that V + AH are underpinned by an impairment in reality-monitoring processes. The objective of the present study was to test whether reality-monitoring deficits were associated with V + AH in schizophrenia. This study examined reality-monitoring abilities in two groups of patients with schizophrenia: a group of patients with V + AH (n = 24) and a group of patients with AH only (n = 22). Patients with V + AH were significantly more likely to misremember imagined words as being perceived from an external source, compared to patients with AH only (p = 0.008, d = -0.82). In other words, V + AH patients display a larger externalization bias than patients with AH only. One explanation for these results could be that experiencing hallucinations in two sensory modalities may contribute to increased vividness of mental imagery and, in turn, lead to disruption in reality-monitoring processes. This study helps to refine our understanding of the cognitive processes underlying the presence of both auditory and visual hallucinations in patients with schizophrenia.
Methodius of Olympus has often been relegated to unique status, somehow cut off from the wider trends of late Imperial literature. This is partially due to the difficult status of his corpus and the opaque nature of his biography, but also partially due to the period in which he lived. Because we do not know much about the late third century, scholars are often left to think about this period very quickly and as a transition. And while there have been many attempts to look squarely at it as a period of political transition, there have been fewer attempts to linger over this period as a holistic literary landscape. The despair of either well-known primary sources or ancient historical narratives to guide such a study has not encouraged scholars to dedicate much energy to such a task, and even those who have tried often ignore the writer who is the subject of this book. In neglecting Methodius, scholarship has also neglected the opportunity to create a fuller picture of the literary world of the third century.
Literature in the Imperial period often displays a love of collection and compilation. The miscellanies of Aelian (both historical and animal), the crazy quilt of Clement of Alexandria’s theological musings in the Stromata and the collected biographies of Diogenes Laertius are only a few of the Severan-era examples of miscellanies. Jason König and Tim Whitmarsh have gone so far as to say that “it is sometimes hard to avoid the impression that accumulation of knowledge is the driving force of all Imperial prose literature” (König and Whitmarsh 2007: 3). And while miscellany could find a home in a variety of genres, there was one genre that was found to be particularly welcoming to the addition of bit upon bit – the Symposium.
In 362 CE, Julian the Apostate issued his famous School Edict, which effectively forbade Christians from teaching pagan texts. Decried by pagan and Christian alike, it also led to a rush of creative writing from a Christian father and son of the same name who were already well known as rhetoricians, the Apollinarii. The church historians Socrates and Sozomen relate that they took to transforming the Christian scriptures into new genres, to provide substitutes for the traditional pagan texts that were now forbidden for Christian teachers to use. The historical books of the Old Testament were translated into a mixture of heroic verse and tragedy, the Psalms into dactylic hexameter. But the Gospels were transformed into Platonic dialogues. In many ways, the intuition of the Apollinarii was a natural one: Jesus, like Socrates, was a wise man who spread his teaching through personal conversation and interaction, sometimes in the context of celebratory meals, until suffering death at the hands of the state for his subversive teaching. However, the choice seems far from natural to other readers and thinkers, especially certain modern scholars. For them, the playful seriousness and genuine openness of the Socratic-inspired dialogues of Plato (and presumably the other Socratics) is antipathetical to the spirit of Christianity.
Writers of the Greek Imperial period believed that they were living in a great period of prose; it was an element of their self-conscious periodization. When a visitor to Delphi asks in Plutarch’s The Oracles at Delphi are No Longer Given in Verse why the Pythia no longer gives poetic prophecies, the interlocutor Theon explains that it is not only the Pythia that has moved from verse to prose, but a large number of other genres of literature have made the change as well, such as history and philosophy. Modern scholars tend to agree with this ancient assessment. The rise of the novel, the Gospels, the cultural capital of display oratory, even the emphasized innovation of Aelius Aristides’ composition of prose hymns is adduced by modern scholars as evidence of a change that was noticed by authors of the time.
Silence is a good thing … If you will learn and discover, silence is a friend and a fellow-worker. But seeking eloquence and aptitude, you will find it in speech and nowhere else, or in words and in their continuous practice.
If dialogues should lead to new dialogues, to the opening up of new topics to explore and discuss, then it is my hope that this book will do the same. In particular, I have had little room in this book to look at the other surviving dialogues of Methodius, although On Free Will, On the Resurrection and On Leprosy have had a certain role to play in the story that I have told. My hope is that future scholars interested in the literature of the transitional period of the Crisis of the Third Century will take up the challenge of reading and analyzing these fascinating and woefully understudied texts. Even more fundamentally, I hope that this book has contributed to two larger scholarly projects. I hope that it has convinced scholars of Imperial literature that they ignore Christian evidence to their own loss, and I hope that I have convinced scholars of Late Antiquity that interesting things are happening in the field of literature.
As driving instructors and philosophers alike tell us, where you look has a lot to do with where you end up going. Focusing on a billboard may result with you and your car in a ditch. And where your imagination lovingly lingers forms who you become. This book examines a moment when authors were struggling to redirect the gaze, and thereby the path, of a generation during the period of the “Crisis of the Third Century,” the tipping-point between the period typically referred to as the “Second Sophistic” and the period that has come to be known as “Late Antiquity.” Through the prism of a particularly creative author of the late third century, I will argue in this book that Greek Imperial literature can be read with more depth and subtlety as an aesthetic battle between a rhetoric of the old and a rhetoric of the new.