High power-high voltage waterload Patent

Variable water load for dissipating large amounts of electrical power during high voltage power supply test

Adiabatic Motion of a Quantum Particle in a Two-Dimensional Magnetic Field

The adiabatic motion of a charged, spinning, quantum particle in a two - dimensional magnetic field is studied. A suitable set of operators generalizing the cinematical momenta and the guiding center operators of a particle moving in a homogeneous magnetic field is constructed. This allows us to separate the two degrees of freedom of the system into a {\sl fast} and a {\sl slow} one, in the classical limit, the rapid rotation of the particle around the guiding center and the slow guiding center drift. In terms of these operators the Hamiltonian of the system rewrites as a power series in the magnetic length \lb=\sqrt{\hbar c\over eB} and the fast and slow dynamics separates. The effective guiding center Hamiltonian is obtained to the second order in the adiabatic parameter \lb and reproduces correctly the classical limit.Comment: 17 pages, LaTe

Diagonalization of multicomponent wave equations with a Born-Oppenheimer example

A general method to decouple multicomponent linear wave equations is presented. First, the Weyl calculus is used to transform operator relations into relations between c-number valued matrices. Then it is shown that the symbol representing the wave operator can be diagonalized systematically up to arbitrary order in an appropriate expansion parameter. After transforming the symbols back to operators, the original problem is reduced to solving a set of linear uncoupled scalar wave equations. The procedure is exemplified for a particle with a Born-Oppenheimer-type Hamiltonian valid through second order in h. The resulting effective scalar Hamiltonians are seen to contain an additional velocity-dependent potential. This contribution has not been reported in recent studies investigating the adiabatic motion of a neutral particle moving in an inhomogeneous magnetic field. Finally, the relation of the general method to standard quantum-mechanical perturbation theory is discussed

Spectrometric study of condensed phase species of thorium and palladium-based modifiers in a complex matrix for electrothermal atomic absorption spectrometry

The chemical and morphological transformations of condensed phase species of a thorium-based modifier were studied over the temperature range 200–2500 °C, without and with the presence of aluminium and silicon as matrix components, and in some instances, arsenic as an analyte element. A similar study was also conducted with palladium as the modifier, for comparison. Results were derived using scanning electron microscopy (SEM), energy dispersive (ED) X-ray spectrometry, Raman microanalysis and attenuated total reflectance (ATR) Fourier transform-infrared (FT-IR) spectrometry. Comparable results were found using pyrolytic and non-pyrolytic graphite platforms, with processes occurring at slightly higher temperatures on the pyrolytic graphite platform. With thorium as the modifier, metal oxides were the predominant species on the platform surface at relatively low temperatures (<1500 °C), whereas metal phases became prevalent at high temperatures, when thorium and aluminium tended to behave independently from one other. Some spatial variations in the composition of the salt residues on different regions of the platform were observed (from the region closest to the slot in the tube, to the region furthest from the slot). Nonetheless, thorium metal remained on the graphite platform to higher temperatures than did aluminium metal. In the presence of arsenic, the existence of mixtures of thorium and arsenic oxides, just before the appearance temperature of gas phase arsenic atoms, was confirmed by SEM studies, ED X-ray spectra and Raman microanalysis. This suggests that any modifying effect of thorium on arsenic occurs while the modifier is in the oxide phase rather than in the metal phase. The presence of silicon added as silica, did not influence significantly the thermochemical behaviour of mixtures of thorium and aluminium. However, coexistence of silicon and arsenic oxides at the appearance temperature of the atomic absorption signal of arsenic was obtained, confirming that silicon can act as an internal modifier for arsenic. In the presence of palladium, aluminium exhibited greater interaction with the modifier; consequently, aluminium metal was retained on the platform surface to higher temperatures than thorium, which could explain how interference effects of aluminium on e.g. arsenic are avoided or reduced. Similarly, there was evidence for interaction of palladium and arsenic in the reduced state. However, when aluminium and silicon were present, the transformation of the palladium oxide to the metallic state was affected, which could diminish the modifying benefits of palladium for arsenic in the presence of aluminium

You make yourself entirely available”: Emotional Labour in a caring approach to teaching

This study examines the challenges experienced, and the pedagogy adopted, by university teachers as they transferred their teaching online during the Covid-19 pandemic. Thematic analysis of survey and interview data show that teachers engaged regularly in emotional support of students, and a pedagogy of care was discernible in the ways teachers described seeking out signals that the students’ needs were being met online. However, technology mediated communication made this more difficult in online teaching than face-to-face, increasing teachers’ emotional labour. Teachers’ efforts to achieve interaction with, and feedback from, students to inform their teaching approach, incurred a heavy burden of emotional labour that is insufficiently recognised or rewarded. This study has implications for the debate around the justification of equivalent fees for online teaching, since it reveals more emotional labour is involved. Universities risk burnout of experienced educators unless the emotional labour in online teaching is acknowledged and supported. Moreover, since emotional labour is often borne by the least privileged sections of the university workforce, this study uncovers uncomfortable questions about the persistence of systemic problems causing staff inequalities that cannot afford to be ignored

Gender and the Lived Body Experience of Academic Work during Covid19

The rapid transition to online teaching in response to Covid-19 presented unprecedented challenges for academic communities. Staff had vastly different experiences of engaging with technology, and these experiences are shaped by factors including gender, (dis)ability, socio-economic resources and caring responsibilities. We report findings from an intersectional interview examination of how 412 staff in a large London-based university adapted to teaching and researching from home at the beginning of lockdown during the COVID-19 pandemic. In this article, we construct grounded theory around the divisibility of the body, and the conflicts arising from the need to span home and work-life, our findings illustrate how patterns of inequity for women academics converge to construct ways of managing the boundary work of home and work with different degrees of successes. We document how management support and/ or existing expertise were vital to enable women academics to overcome obstacles to equitable work.

Maternal and infant food insecurity in the UK: a problem hiding in plain sight?

Lone parents with children under five are amongst the most food insecure in the UK (Cheong et al, 2021; Tobi et al, 2022). Yet maternal and infant food insecurity experience remains poorly understood in the UK. Drawing on findings from qualitative research conducted with parents of infants and young children, and early years health professionals, this paper highlights the hidden nature of poverty and food insecurity amongst young mothers and asks questions about the extent to which this problem is recognised and understood within health care. Two interview studies were conducted during 2020 and 2021 with 22 participants in north-east Scotland, including pregnant women and mothers with at least one child under five. One study included interviews with 18 midwives, health visitors and family nurses (HCP). The studies investigated experiences of parenting on a low income, and health professional support related to financial hardship challenges during pregnancy and early infancy. health professionals' perceptions of poverty within caseloads and experiences of raising financial issues during practice were also investigated. Data were thematically analysed using Grounded Theory principles. Key parent themes included: inadequate social security income co-existing with restricted access to paid employment; anxieties around food and other resource provision for their children; going without food themselves; and relying on charity or extended family for help with feeding. Fear of raising child protection concerns, shame and embarrassment, and exacerbating partner abuse prevented parents disclosing financial hardship and food insecurity to health professionals. Health professionals themselves were aware of poverty within some households, but not universally confident they could recognise the problem. They were also inhibited from raising the issue both because of poverty stigma, and further because of a lack of time and knowledge regarding how to do so effectively. Our findings point to the economic, nutritional and social vulnerability of lone parents that existed before the current cost-of-living crisis. As mothers continue to remain responsible for infant feeding - either as food producers themselves or through infant formula procurement from commercial sources (Frank, 2018; Doonan, 2018) - there is an urgent need to develop a better understanding of the nature and extent of maternal and infant food security in the UK, to develop more effective public policy and health care practice

Product rule for gauge invariant Weyl symbols and its application to the semiclassical description of guiding center motion

We derive a product rule for gauge invariant Weyl symbols which provides a generalization of the well-known Moyal formula to the case of non-vanishing electromagnetic fields. Applying our result to the guiding center problem we expand the guiding center Hamiltonian into an asymptotic power series with respect to both Planck's constant $\hbar$ and an adiabaticity parameter already present in the classical theory. This expansion is used to determine the influence of quantum mechanical effects on guiding center motion.Comment: 24 pages, RevTeX, no figures; shortened version will be published in J.Phys.

Standing in a Garden of Forking Paths

According to the Path Principle, it is permissible to expand your set of beliefs iff (and because) the evidence you possess provides adequate support for such beliefs. If there is no path from here to there, you cannot add a belief to your belief set. If some thinker with the same type of evidential support has a path that they can take, so do you. The paths exist because of the evidence you possess and the support it provides. Evidential support grounds propositional justification. The principle is mistaken. There are permissible steps you may take that others may not even if you have the very same evidence. There are permissible steps that you cannot take that others can even if your beliefs receive the same type of evidential support. Because we have to assume almost nothing about the nature of evidential support to establish these results, we should reject evidentialism