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The two-dimensional stability of vertically sheared inertial oscillations at ocean fronts is explored through a linear stability analysis and nonlinear simulations. Baroclinic effects reduce the minimum frequency of inertia-gravity waves to an extent determined by the balanced Richardson number ${{Ri}}$ of the front. Below a critical value of ${{Ri}}$, which depends on the strength of the inertial shear, the inertial oscillations become unstable to parametric subharmonic instability (PSI) resulting in growing perturbations that oscillate at half the inertial frequency $f$. Since the critical value is always greater than 1, PSI can occur at fronts stable to symmetric instability. Although modest in weak inertial shear, growth rates exceeding $f/2$ can be achieved for inertial shear greater than or equal to the thermal wind shear. Our formulation allows for non-hydrostatic perturbations and can be applied to initially unstratified geostrophic adjustment problems. We find that PSI will almost totally damp the transient oscillations that arise during geostrophic adjustment. The perturbations gain energy at the expense of the inertial oscillations through ageostrophic shear production. The perturbations then themselves become unstable to secondary Kelvin–Helmholtz instabilities creating a pathway by which the inertial oscillations can be dissipated rapidly. In contrast to symmetric and baroclinic instabilities that draw on a front's kinetic or potential energy, PSI acts to increase the energy stored in the balanced front as the convergence and divergence of the eddy-momentum fluxes set up a secondary circulation in the sense to stand up the front.
In this article, we establish three new versions of Landau-type theorems for bounded bi-analytic functions of the form $F(z)=\bar {z}G(z)+H(z)$, where G and H are analytic in the unit disk with $G(0)=H(0)=0$ and $H'(0)=1$. In particular, two of them are sharp, while the other one either generalizes or improves the corresponding result of Abdulhadi and Hajj. As consequences, several new sharp versions of Landau-type theorems for certain subclasses of bounded biharmonic mappings are proved.
‘Post-Keynesian’ became an umbrella term for those heterodox economists wanting to move away from the dominant neo-classical paradigm but not comfortable with another umbrella term of ‘political economy’. This review is about the contributions to understanding societal and economic change from an established and internationally recognised group of post-Keynesian economists. Many of the features which differentiate them from other, and sometimes fluid, subsets of post-Keynesian economists derive from their Kaleckian inspiration.
This work presents a new formulation to holistically control four cooperative multi-rotor drones controlled in two pairs. This approach uses a modular relative Jacobian with components consisting of the Jacobians of each individual drone. This type of controller relies mainly on the relative motion between the drones, consequently releasing unnecessary constraints inherent to the control of drones in absolute motion. We present the derivations of all the necessary equations of the modular relative Jacobian to control the four multi-rotor drones. We also present the derivations of the Jacobian for each drone. We implement our proposed method in the Gazebo RotorS simulation using four hexa-rotor drones modeled from Ascending Technologies called firefly drones. We present the simulation results and analyze them to show the effectiveness of our proposed approach.
As the silence of male CRSV victims continues to be debated, some argue that gender norms and a lack of agency contribute to the silence of victims, even as others assert that victims exercise agency by speaking selectively about their experiences. In northern Nigeria, the concept of kunya—a model for appropriate behaviour rooted in the importance of secrecy and discretion—plays a role in the silencing of victims. We examine how kunya contributes to the invisibility of victims and influences their silence, as well as how victims use silence to gain social tolerability and/or protect themselves from re-victimization. We argue that an attentiveness to such community-specific cultural precepts and norms can further our understanding of the silence (and silencing) of victims and survivors.
We introduce and analyze a new axiomatic theory $\mathsf {CD}$ of truth. The primitive truth predicate can be applied to sentences containing the truth predicate. The theory is thoroughly classical in the sense that $\mathsf {CD}$ is not only formulated in classical logic, but that the axiomatized notion of truth itself is classical: The truth predicate commutes with all quantifiers and connectives, and thus the theory proves that there are no truth value gaps or gluts. To avoid inconsistency, the instances of the T-schema are restricted to determinate sentences. Determinateness is introduced as a further primitive predicate and axiomatized. The semantics and proof theory of $\mathsf {CD}$ are analyzed.
Meta-analyses are used to synthesize a body of literature to produce a single summary estimate as well as to explain differences among studies. The field of political science has slowly gained an appreciation for their use in recent years; however, using meta-analyses in dissertations remains rare. This is puzzling, given the tool’s ability to map a topic, to highlight potential gaps for future research to address, and its long-lasting utility for researchers in future projects. We argue that for these and several other reasons, graduate students should consider including a meta-analysis in their dissertation. This article discusses these advantages in detail and offers advice on how to conduct a meta-analysis based on several interviews and applied examples. We also address potential challenges when using this research design in a dissertation.
We introduce prime products as a generalization of ultraproducts for positive logic. Prime products are shown to satisfy a version of Łoś’s Theorem restricted to positive formulas, as well as the following variant of the Keisler Isomorphism Theorem: under the generalized continuum hypothesis, two models have the same positive theory if and only if they have isomorphic prime powers of ultrapowers.
During the coronavirus disease 2019 pandemic, ENT-UK recommended a move from face-to-face clinics to telephone appointments. This study reviewed the safety of telephone clinics for urgent two-week-wait cancer referrals.
Methods
Patients consulted in telephone clinics between April and November 2020 were identified from an electronic database. Study patients included those diagnosed with malignant disease at six months. The Head and Neck Cancer Risk Calculator version 2 score, outcome of the initial clinic and final diagnoses were reviewed.
Results
A total of 1062 patients were triaged in clinic; 9.2 per cent (n = 98) were diagnosed with cancer at 6 months. Of these 98 patients, 69 received an urgent face-to-face appointment, 26 underwent urgent scans and 3 had a delayed telephone review. Twenty patients (20.4 per cent) diagnosed with cancer had a low-risk Head and Neck Cancer Risk Calculator score.
Conclusion
The late diagnosis rate of 0.28 per cent suggests a small proportion of cancer could have been missed. Telephone clinics, whilst a pragmatic means to maintain patient flow during the pandemic, could result in late diagnoses.
Compassion fatigue is a condition that occurs in individuals who are continuously involved in providing care or emotional support to others who are experiencing suffering or difficulties. This condition can affect the physical, emotional, and psychological well-being of health professionals. The results of a literature review show that music therapy can effectively reduce stress levels, emotional exhaustion, and burnout symptoms associated with compassion fatigue. This article proposes the use of music therapy as an effective alternative to reduce compassion fatigue.
Given $\alpha \gt 0$ and an integer $\ell \geq 5$, we prove that every sufficiently large $3$-uniform hypergraph $H$ on $n$ vertices in which every two vertices are contained in at least $\alpha n$ edges contains a copy of $C_\ell ^{-}$, a tight cycle on $\ell$ vertices minus one edge. This improves a previous result by Balogh, Clemen, and Lidický.
With a growing interest in low Reynolds number compressible flows, compressibility effects on the secondary instabilities developing on the circular cylinder periodic wake are investigated. The unsteady and time-averaged two-dimensional flows are characterised for Reynolds numbers ${{Re}} \in [200;350]$ and Mach numbers up to ${{M}}_{\infty }=0.5$, revealing different flow structures which influence the characteristics of the secondary unstable modes. The two-dimensional time-periodic solution is used as the base state for a global linear stability analysis performed by means of Floquet theory coupled with a time-stepping finite-difference approach of the nonlinear operator. The influence of compressibility on mode A and mode B secondary instabilities which are responsible for the three-dimensionalisation of the two-dimensional periodic wake is analysed. A stabilising or a destabilising effect of compressibility is observed on mode A, depending on the Reynolds number and the spanwise wavelength of the mode, while mode B is stabilised by the increase of the Mach number. Compressibility is indeed found to decrease the mode kinetic energy production due to base flow shear conversion, which drives the growth of mode B. This results in a delay of the three-dimensionalisation process of the wake due to compressibility.
We use New York City (NYC) taxi data to identify trips between mutual fund offices and local firm headquarters. NYC funds overweight the stocks of local firms they visit via taxi, and firm visits are associated with superior investment performance. Firm visits are elevated prior to earnings announcements, and mutual fund trades that are associated with firm taxi visits predict earnings surprises. The results are generally stronger when fund and firm executives share educational connections. Additional tests support the conclusion that funds’ local bias and investment performance are driven by portfolio managers’ efforts and ability to actively gather material information.
The use of prostaglandin E1 is well documented in ductus arteriosus-dependent CHD or in neonatal pulmonary pathologies that cause severe pulmonary hypertension. The intravenous infusion is well established in loading infusion and maintenance with an onset of action of 30 minutes until 2 hours or even more. Our aim is to report three patients with pulmonary atresia that presented hypercyanotic spell due to a ductal spasm during cardiac catheterisation in whom the administration of a bolus of alprostadil reversed the spasm and increased pulmonary flow, immediately stabilising the condition of the patients allowing subsequent successful stent placement with no serious complications or sequelae after the administration of the bolus. More studies are needed to make a recommendation regarding the use of alprostadil in bolus in cases where the ductal spasm might jeopardise the life of the patient.
Developmentalists have increasingly concluded that systems approaches to resilience provide a useful higher-order home for the study of the development of coping. Building on previous work on the complementarity of resilience and coping, this paper had two goals: (1) to propose a set of strategies for examining the role of coping in processes of resilience, and (2) to test their utility in the academic domain, using poor relationships with the teacher as a risk factor, and classroom engagement as an outcome. This study examined whether coping serves as a: (1) promotive factor, supporting positive development at any level of risk; (2) pathway through which risk contributes to development; (3) protective factor that mitigates the effects of risk; (4) reciprocal process generating risk; (5) mechanism through which other promotive factors operate; (6) mechanism through which other protective factors operate; and (7) participant with other supports that shows cumulative or compensatory effects. Analyses showed that academic coping at this age was primarily a mediator of risk and support, and a promotive factor that added to engagement for students with multiple combinations of risk and support. Implications are discussed, along with next steps in exploring the role of coping in processes of resilience.
During the early first millennium BC, Phoenician peoples settled the Iberian coasts instigating cultural innovations known as the orientalising; indigenous communities of the interior have long been considered as passively dependent on, or isolated from, these developments. Recent excavations at the Early Iron Age village of Cerro de San Vicente in central Spain, however, have yielded domestic contexts that prompt reconsideration of this relationship. The authors use settlement layout, architecture and locally made tablewares to identify heterarchical organisation around virilocal and bilateral kinship and hybrid practices that attest to adoption of know-how and practices from distant places. Emphasis is placed on the role of embodied craftworking skills and female mobility in transculturation processes.
Robinson’s unification algorithm can be identified as the underlying machinery of both C. Meredith’s rule D (condensed detachment) in propositional logic and of the construction of principal types in lambda calculus and combinatory logic. In combinatory logic, it also plays a crucial role in the construction of Meyer, Bunder & Powers’ Fool’s model. This paper now considers pattern matching, the unidirectional variant of unification, as a basis for logical inference, typing, and a very simple and natural model for untyped combinatory logic. An analysis of the new typing scheme will enable us to characterize a large class of terms of combinatory logic which do not change their principal type when being weakly reduced. We also consider the question whether the major or the minor premisse should be used as the fixed pattern.