Multiple vanishing tumours simulating pulmonary neoplasms. A case report

CITATION: Van Gelderen, W.F.C. 1989. Multiple vanishing tumours simulating pulmonary neoplasms. A case report. S Afr Med J, 75:498-499.The original publication is available at http://www.samj.org.zaVanishing fluid collection (or tumour) in an interlobar fissure associated with congestive cardiac failure is not common. Multiple vanishing tumours are most uncommon and can resemble other multiple opacities, e.g. metastases. The disappearance of these so-called tumours after treatment for cardiac failure provided proof of the diagnosis in the patient reported. This diagnosis is important to consider in order to prevent unnecessary investigation and treatment.Publisher’s versio

Writing-to-learn in biology and mathematics teacher education:Promoting students’ topic knowledge and insight

In the present study, effects of Genre Writing instruction added with planning and revising activities (GWPR) are investigated in teacher education. This type of instruction was considered promising because it appeared to lead to positive effects on topic knowledge and insight in previous studies conducted in secondary education. Researchers’ expectation was that writing-to-learn activities by means of GWPR support teacher candidates in acquiring topic knowledge and insight into subject matter. Two studies were undertaken, one in biology and one in mathematics teacher education, each comprising a quasi-experiment and a think-aloud study. Both studies were embedded in regular courses. Researchers co-created writing-to-learn tasks with the teacher educators involved. Both experiments showed positive effects on learning. Results of the think-aloud studies provided evidence for specific indicators (students’ reflections) of the process of writing-to-learn, in which experimental teacher candidates differed from the control group. Finally, we discuss the impact of the results for the theory, follow-up studies and teaching practice

Cervical intra-epithelial neoplasia in HIV-positive women after excision of the transformation zone – does the grade change?

Objective. After previously reporting the presence of disease by cytology findings after treatment for cervical intra-epithelial neoplasia (CIN) in 64.6% of HIV-infected women and in 13.0% of HIV-negative women, we aimed to determine the severity of cytological disease after treatment in HIV-infected women.Methods. We studied HIV-infected (N=571) women treated at the Colposcopy Clinic at Chris Hani Baragwanath Hospital, Gauteng, between April 2003 and December 2006. We compared the initial histology results with Pap smears .6 months later, and evaluated factors associated with reduction in the grade of disease.Results. Mean age was 36.68 (SD+7.33) years; mean parity was 2 (SD+1.46); mean CD4+ count was 242.70 cells/ƒÊl (SD+187.56); 262 (45.80%) were receiving antiretroviral treatment. Persistent disease was detected on the repeat Pap smear in 199 (65.03%); of these, 223 (72.88%) were of a lesser grade than in the original histology results. Of the 152 with histologically confirmed CIN3, 67 (44.08%) had improved to a lesser grade, and 54 (44.63%) had normal cytology results. Among the latter two subject groups (n=141) who had CIN2 histologically, 91 (64.53%) had improved, 29 (20.57%) remained unchanged, and 20 (14.88%) had CIN3; 13 (4.25%) patients with CIN1 returned for follow-up; 11 (84.62%) of these had normal Pap smears and 2 (15.38%) had CIN3.Conclusion. Recurrences were of a lesser degree than initial histology results. This reduction in the grade of disease was related to CD4+ count, complete excision and parity. Antiretroviral therapy use did not improve outcome, perhaps owing to low initial CD4 counts

Exposure-related cortisol predicts outcome of psychotherapy in veterans with treatment-resistant posttraumatic stress disorder

Background: Hypothalamic-pituitary-adrenal axis functioning has been related to treatment outcome in posttraumatic stress disorder (PTSD). Previous studies have primarily focused on cortisol levels before and after a course of therapy and findings have not been fully consistent. This study investigated session-related cortisol levels in veterans with treatment-resistant PTSD over the course of a novel motion-assisted virtual reality exposure therapy and aimed to determine whether cortisol levels were related to changes in PTSD symptom severity.Methods: Veterans (N = 22) received six exposure sessions during which salivary cortisol samples were collected pre-session, post-session and in the late afternoon following sessions. PTSD symptom severity was assessed by structured clinical interviews at pre- and post-treatment. Average cortisol levels were compared between responders and non-responders. Linear regression analyses were conducted with PTSD symptom change as criterion variable, average cortisol levels as predictor, and timing of sampling and baseline PTSD symptoms as covariates.Results: Responders to treatment tended to have higher average cortisol levels at pre-session (p = 0.064) and postsession (p = 0.050) compared to non-responders. Higher average pre-session and post-session cortisol levels predicted greater PTSD symptom improvement (pre: b = 1.83, p = 0.009; post: b = 3.57, p = 0.004).Conclusion: This study provides preliminary evidence for session-related cortisol as biomarker of response to exposure-based therapies for PTSD. Higher cortisol levels may have facilitated fear extinction and reconsolidation, and may indicate increased physiological stress activation necessary for appropriate treatment engagement. Further work involving comparable methodology is encouraged to establish session-related cortisol as biomarker and to determine the mechanisms through which it interacts with treatment outcome.Metabolic health: pathophysiological trajectories and therap

Quantum dots and spin qubits in graphene

This is a review on graphene quantum dots and their use as a host for spin qubits. We discuss the advantages but also the challenges to use graphene quantum dots for spin qubits as compared to the more standard materials like GaAs. We start with an overview of this young and fascinating field and will then discuss gate-tunable quantum dots in detail. We calculate the bound states for three different quantum dot architectures where a bulk gap allows for confinement via electrostatic fields: (i) graphene nanoribbons with armchair boundary, (ii) a disc in single-layer graphene, and (iii) a disc in bilayer graphene. In order for graphene quantum dots to be useful in the context of spin qubits, one needs to find reliable ways to break the valley-degeneracy. This is achieved here, either by a specific termination of graphene in (i) or in (ii) and (iii) by a magnetic field, without the need of a specific boundary. We further discuss how to manipulate spin in these quantum dots and explain the mechanism of spin decoherence and relaxation caused by spin-orbit interaction in combination with electron-phonon coupling, and by hyperfine interaction with the nuclear spin system.Comment: 23 pages, 10 figures, topical review prepared for Nanotechnolog

CaB_6: a new semiconducting material for spin electronics

Ferromagnetism was recently observed at unexpectedly high temperatures in La-doped CaB_6. The starting point of all theoretical proposals to explain this observation is a semimetallic electronic structure calculated for CaB_6 within the local density approximation. Here we report the results of parameter-free quasiparticle calculations of the single-particle excitation spectrum which show that CaB_6 is not a semimetal but a semiconductor with a band gap of 0.8 eV. Magnetism in La_xCa_{1-x}B_6 occurs just on the metallic side of a Mott transition in the La-induced impurity band.Comment: 4 pages, 1 postscript figur

Edge States of Monolayer and Bilayer Graphene Nanoribbons

On the basis of tight-binding lattice model, the edge states of monolayer and bilayer graphene nanoribbons (GNRs) with different edge terminations are studied. The effects of edge-hopping modulation, spin-orbital coupling (SOC), and bias voltage on bilayer GNRs are discussed. We observe the following: (i) Some new extra edge states can be created by edge-hopping modulation for monolayer GNRs. (ii) Intralayer Rashba SOC plays a role in depressing the band energy gap $E_g$ opened by intrinsic SOC for both monolayer and bilayer GNRs. An almost linear dependent relation, i.e., $E_g\sim \lambda_R$, is found. (iii) Although the bias voltage favors a bulk energy gap for bilayer graphene without intrinsic SOC, it tends to reduce the gap induced by intrinsic SOC. (iv) The topological phase of the quantum spin Hall effect can be destroyed completely by interlayer Rashba SOC for bilayer GNRs.Comment: 6 pages, 6 figure

Electronic Structure of Calcium Hexaboride within the Weighted Density Approximation

We report calculations of the electronic structure of CaB$_6$ using the weighted density approximation (WDA) to density functional theory. We find a semiconducting band structure with a sizable gap, in contrast to local density approximation (LDA) results, but in accord with recent experimental data. In particular, we find an $X$-point band gap of 0.8 eV. The WDA correction of the LDA error in describing the electronic structure of CaB$_6$ is discussed in terms of the orbital character of the bands and the better cancelation of self-interactions within the WDA.Comment: 1 figur

Nonlinear Magneto-Optics of Fe Monolayers from first principles: Structural dependence and spin-orbit coupling strength

We calculate the nonlinear magneto-optical response of free-standing fcc (001), (110) and (111) oriented Fe monolayers. The bandstructures are determined from first principles using a full-potential LAPW method with the additional implementation of spin-orbit coupling. The variation of the spin-orbit coupling strength and the nonlinear magneto-optical spectra upon layer orientation are investigated. We find characteristic differences which indicate an enhanced sensitivity of nonlinear magneto-optics to surface orientation and variation of the in-plane lattice constants. In particular the crossover from onedimensional stripe structures to twodimensional films of (111) layers exhibits a clean signature in the nonlinear Kerr-spectra and demonstrates the versatility of nonlinear magneto-optics as a tool for in situ thin-film analysis.Comment: 28 pages, RevTeX, psfig, submitted to PR