Internal structure of preformed Cooper pairs

In order to obtain information about the internal structure of the preformed pairs in the pseudogap state of high $T_c$ superconductors, we calculate the propagator of a singlet pair with center of mass coordinate $\mathbf{r}$, and relative distance $\pmb{\rho}$, by solving the Bethe-Salpeter equation, representing the sum over repeated two-particle scattering events due to a distance dependent attraction. We define then a ``pair structure function'' $g_{P}(\mathbf{P},\pmb{\rho})$ that depends on the internal distance $\pmb{\rho}$ between the partners and on the momentum $\mathbf{P}$ of the pair. We calculate this function both for a local potential and $s-$wave symmetry of the order parameter and for a separable potential and $d-$wave symmetry of the order parameter. The influence of the center of mass momentum, strenght of the interaction, temperature, density of particles and of the pseudogap in the one-electron spectrum is studied for both cases.Comment: 12 pages, REVTeX4, 8 EPS figure

Charge-Spin Separation in 2D Fermi Systems: Singular Interactions as Modified Commutators, and Solution of 2D Hubbard Model in Bosonized Approximation

The general 2-dimensional fermion system with repulsive interactions (typified by the Hubbard Model) is bosonized, taking into account the finite on-shell forward scattering phase shift derived in earlier papers. By taking this phase shift into account in the bosonic commutation relations a consistent picture emerges showing the charge-spin separation and anomalous exponents of the Luttinger liquid.Comment: Latex file 14 pages. email: [email protected]

WHAT IS HAPPENING IN AN INDIVIDUAL SUPERVISION SESSION? REFLECTIONS OF SOCIAL WORKERS IN SOUTH AFRICA

This article reports on qualitative research, aimed at acquiring an understanding of what transpires in an individual social work supervision session in South Africa. Findings reveal that supervision sessions are chiefly “open door” and “on the run”, with minimal evidence of critical reflection. A key recommendation stresses that the evolution of supervision in the country should enter a new phase as response to the hegemony of a neoliberal inspired managerial discourse in social work. The deliberate utilisation of more clinical educational and supportive elements, and critical reflection-in-action and reflection-on-action in supervision sessions is therefore recommended

One-Particle Excitation of the Two-Dimensional Hubbard Model

The real part of the self-energy of interacting two-dimensional electrons has been calculated in the t-matrix approximation. It is shown that the forward scattering results in an anomalous term leading to the vanishing renormalization factor of the one-particle Green function, which is a non-perturbative effect of the interaction U. The present result is a microscopic demonstration of the claim by Anderson based on the conventional many-body theory. The effect of the damping of the interacting electrons, which has been ignored in reaching above conclusion, has been briefly discussed.Comment: 7 pages, LaTeX, 1 figure, uses jpsj.sty, to be published in J. Phys. Soc. Jpn. 66 No. 3 (1997

A multifaceted hospital-wide intervention increases hand hygiene compliance

Background. Hand hygiene is an important and basic practice that should be used by all healthcare staff to protect both themselves and their patients against infection. Unfortunately hand hygiene compliance remains poor.Objective. To show an improvement in hand hygiene compliance using a multifaceted approach.Methods. This was a quasiexperimental pre-post intervention study design with a number of standardised interventions to promote hand hygiene. The World Health Organization hand hygiene multimodal (five-step) intervention approach was used. The study ran from June 2015 to August 2015 in 11 selected wards of a 975-bed tertiary and quaternary care public hospital (Groote Schuur Hospital, Cape Town, South Africa). The outcome was to assess improvement in hand hygiene compliance monthly over the 3 months, compared with nonintervention wards and compared with the wards’ own performance measured in 2014. The study included both descriptive and analytical components.Results. Post intervention, hand hygiene compliance showed a statistically significant improvement for before patient contact from 34% in 2014 to 76% in 2015 (p<0.05) and for after patient contact from 47% in 2014 to 82% in 2015 (p<0.05).Conclusion. The intervention improved hand hygiene compliance and can easily be replicated in other wards, resulting in sustaining a culture of hand hygiene improvement and behavioural change throughout the hospital

Animal-assisted pedagogy:human-animal bond, developmental benefits and practical considerations

Abstract. In recent years, animal-assisted pedagogy (AAP) has gained more attention both in the media and in the educational field. Some schools and libraries have seemed to include animals as a common support in the learning process. This has sparked interest also in educational research, and thus the effects of animals as a part of education have been studied more closely. For this reason, we aim to provide insight to AAP with a literature review that explores this topic from the points of view of human-animal bond, the developmental benefits, and the practical considerations related to it. In addition, we aspire to challenge our own views of AAP and discuss how it might be brought into practice. Based on our research, the human-animal bond is a mutually beneficial relationship that takes place between a human and an animal. Its significance in society and the multitude of benefits it offers, provide a good foundation from which to view AAP. Implementing AAP positively affects the social and emotional competences and motivation of students by the support of the comfort of the animal’s presence, which enables positive experiences and interactions. The animals help to create a safe space that allows the students to feel more confident and secure, and as a result the motivation of learning increases. However, it appears that applying AAP to practice is quite challenging due to the amount of limitations and consideration of bringing an animal into a working environment. For example, allergies, fears and lack of resources may dictate whether it is possible for an educator to practice AAP

Numerical Evidence of Luttinger and Fermi Liquid Behaviour in the 2D Hubbard Model

The two dimensional Hubbard model with a single spin-up electron interacting with a finite density of spin-down electrons is studied using the quantum Monte Carlotechnique, a new conjugate gradient method for the evaluation of the Edwards wavefunction ansatz, and the standard second order perturbation theory. We performed simulations up to 242 sites at $U/t=4$ reaching the zero temperature properties with no ``fermion sign problem'' and found a surprisingly good accuracy of the Edwards wavefunction ansatz at low density or low doping. The conjugate gradient method was then applied to system up to 1922 sites and infinite $U$ for the Edwards state. Fermi liquid theory seems to remain stable in 2D for all cases studied with the exception of the half filling case where a ``Luttinger like behavior'' survives in the Hubbard model , yielding a vanishing quasiparticle weight in the thermodynamic limit.Comment: 10 pages + 4 pictures, RevTex, SISSA 121/93/CM/M

Consistency in Leadership during a Pandemic: Managing Academics at a Private Higher Education Institution in South Africa

The Covid-19 pandemic forced leaders to adapt their leadership approaches to the online environment. This chapter reviews the leadership approaches applied by managers at a Private Higher Education Institution (PHEI) in response to the Covid-19 pandemic and examines how these managers ensured that academics perform optimally while working remotely. A qualitative research methodology, combined with semi-structured interviews, enabled the researcher to source rich data from the managers and academics at the PHEI in question. Most managers indicated that only minor adjustments to their leadership approaches were required to work in a remote online environment. Participants also noted that a combination of various leadership approaches in a specific context enhances a leader’s efficiency, as it allows them to analyze a situation and consider the impact of proposed approaches on stakeholders before a decision is made

Elliptical double corrugated tubes for enhanced heat transfer

The thermal performance at constant pumping power conditions was numerically investigated in ellipse and super ellipse-based double corrugated tubes. A significant increase in thermal efficiency in double corrugated tubes is accompanied with a reasonable penalty in flow reduction for the cases modelled. An ellipse and a super ellipse-based double corrugated tubes were modelled at laminar fully hydraulically developed incompressible flow. Each base geometry was analysed holding either hydraulic diameter constant or the cross-sectional area constant. The pressure drop was normalized to the length of each modelled tube in order to maintain the pumping power. Thermal analysis was conducted under constant wall temperature boundary condition. The governing equations for non-isothermal flow were solved using the finite element method, and the results of the simulations were normalized to an equivalent straight tube. Numerical results predict a thermal efficiency enhanced by 400% maintaining 4.2 times lower volumetric flow rate in double corrugated tubes at the same pressure drop. The global performance evaluation criterion increases up to 14% for the double corrugated tubes with an ellipse-base and up to 11% for the tubes with super ellipse-base

From a magnet to a heat pump

The magnetocaloric effect (MCE) is the thermal response of a magnetic material to an applied magnetic field. Magnetic cooling is a promising alternative to conventional vapor compression technology in near room temperature applications and has experienced significant developments over the last five years. Although further improvements are necessary before the technology can be commercialized.Researchers were mainly focused on the development of materials and optimization of a flow system in order to increase the efficiency of magnetic heat pumps. The project, presented in this paper, is devoted to the improvement of heat pump and cooling technologies through simple tests of prospective regenerator designs. A brief literature review and expected results are presented in the paper. It is mainly focused on MCE technologies and provides a brief introduction to the magnetic cooling as an alternative for conventional vapor compression technology