Summary of electric vehicle dc motor-controller tests

The differences in the performance of dc motors are evaluated when operating with chopper type controllers, and when operating on direct current. The interactions between the motor and the controller which cause these differences are investigated. Motor-controlled tests provided some of the data the quantified motor efficiency variations for both ripple free and chopper modes of operation

Psychosocial Challenges at a Refugee Camp: When Volunteer Preparation is Lacking

This small-scale study was undertaken to learn about training for volunteers participating in a particular nongovernmental organization (NGO) program to help refugees living at a camp in Greece. There is a dearth of research on this topic in spite of the fact that organizations rely heavily on the support of volunteers. The design was that of a pilot case study. It was conducted using observations and interviews of volunteers at the NGO. Findings indicated that volunteers were poorly trained, as the NGO staff had insufficient knowledge about refugees in general, and the refugee population at the camp, in particular. The lack of training resulted in high levels of frustration for the camp residents as well as poor morale and sadness on the part of the volunteers. There are relatively easy solutions for better preparing volunteers to support refugees in transitional camps, including pre-arrival and on-site mentoring on the culture, history, and languages of the predominant camp residents as well as clear instructions on procedures and careful oversight by NGO staff, all of which would result in improved wellbeing for both refugees and volunteers

A large, single pulmonary arteriovenous fistula presenting hours after birth

This article reports a case of a single, large pulmonary artery to left atrial fistula presenting within hours of birth. Symptomatic fistulas of this type are exceptionally rare in the neonatal period. The images of the fistula obtained during echocardiography and cardiac catheterisation is included. This case highlights the importance of intra-operative echocardigraphic guidance during surgical ligation of fistulas of this type.peer-reviewe

The Long Arm of the Law: Executive Overreach and the AUMF

Since World War II, the executive branch has dominated foreign policy and national security decisions, expanding war powers well beyond the president’s constitutional purview. Aided by a complicit Congress, the president has bypassed the legislator and unilaterally prosecuted some of the United States’ bloodiest conflicts. Continuing this tradition of executive overreach, Congress passed the Authorization for the Use of Military Force (AUMF) on September 14, 2001, which ostensibly empowered the president to pursue those responsible for the 9/11 attacks, namely al Qaeda and the nations supporting them. However, the broadly-worded force authorization and equally far-reaching legal interpretations by the executive branch turned the AUMF into a nearly limitless authorization. Since its passage, the AUMF has provided the legal backstop for the war in Afghanistan, drone strikes in Yemen, Somalia, Pakistan, and elsewhere, National Security Agency surveillance, and the Guantanamo Bay detention facility. Enabled by the AUMF, the “war on terror” has eroded civil liberties, allowed extrajudicial killings, and transformed the conflict with al Qaeda into a war without end. In order to end the destructive legacies of the war on terror and begin to reverse the trend of executive overreach, Congress and the president should repeal the AUMF and update the force authorization regime

Using a published scheme for Key Stage 3 design and technology

This article details the way in which one school developed and implemented its Key Stage 3 curriculum by working from a published scheme - in this case the Nuffield materials. The account highlights:the importance of the departmental team establishing their own guiding aims and principles in advance of looking at the published materialsthe value of providing quality professional development for the teachers and quality time for planning and developmentthe importance of including, from the outset, implementing, monitoring and evaluating procedures in the agend

The effect of Poly I:C induced inflammation on hematopoietic stem and progenitor cell behaviour in the zebrafish hematopoietic transplant model

Hematopoietic stem cells are a small but significant population of cells fundamental for generating and maintaining the hematopoietic system. These cells are used in the treatment of cancer and auto-immune patients. Studies in mammals suggest that inflammation and infection can modulate the biology of these cells, affecting their location, self-renewal capacity and directing differentiation. The aim of this work was to study the effect of repeated stimulation on the hematopoietic stem and progenitor (HSPCs) population in zebrafish (Danio rerio) to benefit from the live imaging potential of this model organism. It was hypothesised that early post-transplant HSPC behaviour (e.g. lodgement in the niche, self-renewal, mobilisation and differentiation) could be observed and would be indicative of the success or failure of HCT. Double transgenic Tg (cd41:GFP; lysc:dsRed) donors, in which HSPCs express green fluorescent protein (GFP+) and myeloid cells express red fluorescent protein (dsRed+) were used. HSPCs were sorted from donor whole kidney marrow (WKM) and transplanted into irradiated optically-transparent recipients, which were then imaged using wide-field microscopy, individually tracked for survival and hematopoietic reconstitution was assessed after 28 days by flow cytometry. Indeed, initial experiments showed that early observations of cells in the WKM correlated with hematopoietic recovery and survival of recipients, although the strength of the correlation was not sufficiently powerful for predicting recipient outcome. This refinement of the HCT protocol lead to the potentiality of studying the behaviour of HSPCs in the context of inflammation. Inflammation was initiated with repeated intra-peritoneal injections of the viral mimic Polyinosinic:polycytidylic acid (poly I:C) in either the donor or recipient prior to transplant. Poly I:C injection of donors prior to transplant causes HSPCs to colonise the recipient WKM at a greater rate than HSPCs from sham (PBS-injected) donors. However, this did not appear to affect recipient survival or WKM reconstitution at 28 days. Poly I:C injection of recipients prior to transplant did not affect early post-transplant repopulation of the WKM, myelopoiesis, recipient survival, or WKM reconstitution at 28 days. Future work will use competitive transplants to confirm these findings and will explore alternative inflammation models. Furthermore, the confounding factor of irradiation-caused inflammation will be mitigated by transplanting HSPCs into optically-transparent bloodless recipients. Overall, this thesis has demonstrated that the zebrafish can provide valuable in vivo data for studying HSPC behaviour in the recipient post-transplant.Open Acces

Novel applications of the Josephson Effect: Ferroelectric Characterisation and Capacitively Shunted Grain Boundary Junctions

This thesis describes applications of the ac Josephson effect. Firstly, results are presented from bicrystal grain boundary YBa2Cu3O7-d junctions shunted with a YBa2Cu3O7-d/SrTiO3/Au multilayer external capacitor, to make a junction with a hysteretic current voltage characteristic operating at high temperatures. A hysteretic junction with a McCumber parameter of 1.01 at 72.3K, with a critical current of 451mA and a resistance of 0.56W was achieved for a junction shunted with a 150mm2 external capacitor with a 50nm SrTiO3 dielectric. The measured capacitance was less than that expected from a calculation of the parallel plate shunt capacitance. The explanation was thermal noise suppression of the hysteresis and the junction saw the shunt capacitor as a distributed impedance rather than a lumped circuit element. It was found during these investigations that the influence of the SrTiO3 substrate on the intrinsic junction capacitance was poorly understood. The permittivity of SrTiO3 is 24000 at 4.2K. A series of YBa2Cu3O7-d Josephson junctions of lengths from 2mm to 20mm was patterned on a SrTiO3 bicrystal and the Fiske resonance dispersion relation was measured. The dispersion relation consisted of two branches, one at low frequencies with a high resonator capacitance per unit length and a high frequency branch with a low resonator capacitance per unit length. This was due to the frequency dependence of the permittivity of bulk SrTiO3, which drops above the soft optic phonon frequency. From the dispersion relation, the permittivity of bulk SrTiO3 was 750 and the soft optic phonon frequency was 145GHz. The ac Josephson effect was exploited to measure the permittivity of thin films of SrTiO3 at microwave frequencies using Josephson junctions coupled to external resonators. The permittivity of 50nm, 100nm and 200nm SrTiO3 films was frequency independent between 100GHz and 900GHz and to decrease with film thickness. The permittivity of the 50nm film was 35 and that of the 200nm film was 187 at 4.2K. The permittivity of the 200nm film was tunable with a dc voltage bias between 245 and 112 at 30K and 116GHz. The grain boundary capacitance was used to probe grain boundary current transport. The capacitance per unit area scaled inversely with resistance area product and increased linearly with critical current density, for undoped and Ca doped YBa2Cu3O7-d grain boundaries on 24° bicrystals. This behaviour could not be explained by tunneling models of grain boundary current transport, and requires current flow over a fraction of the area of the grain boundary.EPSR