Zitterbewegung is not an observable

It has recently been claimed that Zitterbewegung has been observed. However, we argue that it is not an observable and that the authors' observations must be reinterpreted

Families and Food in Hard Times: European Comparative Research

Food is fundamental to health and social participation, yet food poverty has increased in the global North. Adopting a realist ontology and taking a comparative case approach, Families and Food in Hard Times addresses the global problem of economic retrenchment and how those most affected are those with the least resources. Based on research carried out with low-income families with children aged 11-15, this timely book examines food poverty in the UK, Portugal and Norway in the decade following the 2008 financial crisis. It examines the resources to which families have access in relation to public policies, local institutions and kinship and friendship networks, and how they intersect. Through ‘thick description’ of families’ everyday lives, it explores the ways in which low income impacts upon practices of household food provisioning, the types of formal and informal support on which families draw to get by, the provision and role of school meals in children’s lives, and the constraints upon families’ social participation involving food. Providing extensive and intensive knowledge concerning the conditions and experiences of low-income parents as they endeavour to feed their families, as well as children’s perspectives of food and eating in the context of low income, the book also draws on the European social science literature on food and families to shed light on the causes and consequences of food poverty in austerity Europe

Note on the derivative of the hyperbolic cotangent

In a letter to Nature (Ford G W and O'Connell R F 1996 Nature 380 113) we presented a formula for the derivative of the hyperbolic cotangent that differs from the standard one in the literature by an additional term proportional to the Dirac delta function. Since our letter was necessarily brief, shortly after its appearance we prepared a more extensive unpublished note giving a detailed explanation of our argument. Since this note has been referenced in a recent article (Estrada R and Fulling S A 2002 J. Phys. A: Math. Gen. 35 3079) we think it appropriate that it now appear in print. We have made no alteration to the original note

Self reported aggravating activities do not demonstrate a consistent directional pattern in chronic non specific low back pain patients: An observational study

Question: Do the self-reported aggravating activities of chronic non-specific low back pain patients demonstrate a consistent directional pattern? Design: Cross-sectional observational study. Participants: 240 chronic non specific low back pain patients. Outcome measure: We invited experienced clinicians to classify each of the three self-nominated aggravating activities from the Patient Specific Functional Scale by the direction of lumbar spine movement. Patients were described as demonstrating a directional pattern if all nominated activities moved the spine into the same direction. Analyses were undertaken to determine if the proportion of patients demonstrating a directional pattern was greater than would be expected by chance. Results: In some patients, all tasks did move the spine into the same direction, but this proportion did not differ from chance (p = 0.328). There were no clinical or demographic differences between those who displayed a directional pattern and those who did not (all p > 0.05). Conclusion: Using patient self-reported aggravating activities we were unable to demonstrate the existence of a consistent pattern of adverse movement in patients with chronic non-specific low back pain