Russell Square: a lifelong resource for teaching and learning

A quarter of a century ago, in 1978, Birkbeck College’s Faculty of Continuing Education (FCE, then the Department for Extra-Mural Studies of the federal University) moved to the offices that it now occupies in numbers 26 and 25 Russell Square. Then, as now, FCE was the one of the largest and most active extra-mural departments of any British university, with an enormous range of courses covering virtually every subject taught in ‘internal’ university departments and many more besides 1. Some of these courses have, from time to time, used Russell Square as a learning resource. Many more staff and students alike have (along with thousands of local workers, tourists and residents) used the square’s gardens for relaxation and recovery, without reflecting on its origins or present significance. This Occasional Paper examines the past and present fabric of Russell Square (‘the Square’) as a resource for teaching and learning. It is a composite narrative assembled by FCE staff whose disciplines range from nature conservation through garden history and architectural history to social policy. It deconstructs the Square as an entity and attempts to decipher some of its ‘meanings’ that provide links between subjects taught within FCE. We hope that it will stimulate discussion about the way this single ‘place’ – our Square - can be ‘seen’ or interpreted in different ways for diverse purposes, and about the way that it can be used as a resource for teaching and learning across disciplines

Growth and maturity of the Pacific razor clam in eastern Cook Inlet, AK

Thesis (M.S.) University of Alaska Fairbanks, 2014In Alaska, the only road-accessible fishery for the Pacific razor clam, Siliqua patula, is located in eastern Cook Inlet, and has been monitored by the Alaska Department of Fish & Game (ADF&G) since 1964. In recent years, a shift has been observed in size, age, and number of clam cohorts in this region, yet little is known about the early life history of razor clams in this region. This study aimed to provide information on length and age at maturity, growth rates, and spawn timing at two beaches in eastern Cook Inlet, Ninilchik and Clam Gulch, in 2009 and 2010. At Clam Gulch, only 20% of the sampled population was reproductive, compared with 83% at Ninilchik. At Ninilchik, clams were reproductive at a smaller size and younger age (p<0.05) than previously documented. The Ninilchik clams grew faster and had a larger size at age (p<0.05) than at Clam Gulch. A body condition index of clams from Clam Gulch was consistently 50% lower than at Ninilchik. Despite the relative proximity (25 km) of these locations, it is possible that environmental conditions may be different, resulting in differences in growth and reproductive output. This information is of special interest to fisheries managers as they address recent declines in the eastern Cook Inlet razor clam population and provides a benchmark for future management decisions

Persistent superfluid flow arising from the He-McKellar-Wilkens effect in molecular dipolar condensates

We show that the He-McKellar-Wilkens effect can induce a persistent flow in a Bose-Einstein condensate of polar molecules confined in a toroidal trap, with the dipolar interaction mediated via an electric dipole moment. For Bose-Einstein condensates of atoms with a magnetic dipole moment, we show that although it is theoretically possible to induce persistent flow via the Aharonov-Casher effect, the strength of electric field required is prohibitive. We also outline an experimental geometry tailored specifically for observing the He-McKellar-Wilkens effect in toroidally-trapped condensates.Comment: 5 pages 2 figure

Direct Improvement of Hamiltonian Lattice Gauge Theory

We demonstrate that a direct approach to improving Hamiltonian lattice gauge theory is possible. Our approach is to correct errors in the Kogut-Susskind Hamiltonian by incorporating additional gauge invariant terms. The coefficients of these terms are chosen so that the order $a^2$ classical errors vanish. We conclude with a brief discussion of tadpole improvement in Hamiltonian lattice gauge theory.Comment: 9 page

On the continuous spectral component of the Floquet operator for a periodically kicked quantum system

By a straightforward generalisation, we extend the work of Combescure from rank-1 to rank-N perturbations. The requirement for the Floquet operator to be pure point is established and compared to that in Combescure. The result matches that in McCaw. The method here is an alternative to that work. We show that if the condition for the Floquet operator to be pure point is relaxed, then in the case of the delta-kicked Harmonic oscillator, a singularly continuous component of the Floquet operator spectrum exists. We also provide an in depth discussion of the conjecture presented in Combescure of the case where the unperturbed Hamiltonian is more general. We link the physics conjecture directly to a number-theoretic conjecture of Vinogradov and show that a solution of Vinogradov's conjecture solves the physics conjecture. The result is extended to the rank-N case. The relationship between our work and the work of Bourget on the physics conjecture is discussed.Comment: 25 pages, published in Journal of Mathematical Physic

Neutrino clustering and the Z-burst model

The possibility that the observed Ultra High Energy Cosmic Rays are generated by high energy neutrinos creating "Z-bursts" in resonant interactions with the background neutrinos has been proposed, but there are difficulties in generating enough events with reasonable incident neutrino fluxes. We point out that this difficulty is overcome if the background neutrinos have coalesced into "neutrino clouds" --- a possibility previously suggested by some of us in another context. The limitations that this mechanism for the generation of UHECRs places on the high energy neutrino flux, on the masses of the background neutrinos and the characteristics of the neutrino clouds are spelled out.Comment: 13 pages and 3 figures. Contributed to the XX International Symposium on Lepton and Photon Interactions at High Energies, Rome, July 2001, and to the International Europhysics Conference on High Energy Physics, Budapest, July 2001. Preprint numbers added, misprints correcte

Construction and analysis of a simplified many-body neutrino model

In dense neutrino systems, such as found in the early Universe, or near a supernova core, neutrino flavor evolution is affected by coherent neutrino-neutrino scattering. It has been recently suggested that many-particle quantum entanglement effects may play an essential role in these systems, potentially invalidating the traditional description in terms of a set of single-particle evolution equations. We model the neutrino system by a system of interacting spins, following an earlier work which showed that such a spin system can in some cases be solved exactly. We extend this work by constructing an exact analytical solution to a more general spin system, including initial states with asymmetric spin distribution and, moreover, not necessarily aligned along the same axis. Our solution exhibits a rich set of behaviors, including coherent oscillations and dephasing and a transition from the classical to quantum regimes. We argue that the classical evolution of the spin system captures the entire coherent behavior of the neutrino system, while the quantum effects in the spin system capture some, but not all, of the neutrino incoherent evolution. By comparing the spin and neutrino systems, we find no evidence for the violation of the accepted one-body description, though the argument involves some subtleties not appreciated before. The analysis in this paper may apply to other two-state systems beyond the neutrino field.Comment: 22 pages, 7 figure

Neutrino masses or new interactions

Recent proposals to study the mass of the "electron" neutrino at a sensitivity of 0.3 eV can be used to place limits on the right handed and scalar charged currents at a level which improves on the present experimental limits. Indeed the neglect of the possibility of such interactions can lead to the inference of an incorrect value for the mass, as we illustrate.Comment: 12 pages and 3 figures. Contributed to the XX International Symposium on Lepton and Photon Interactions at High Energies, Rome, July 2001, and to the International Europhysics Conference on High Energy Physics, Budapest, July 2001. Preprint numbers added, misprints correcte

Resonances in the one-dimensional Dirac equation in the presence of a point interaction and a constant electric field

We show that the energy spectrum of the one-dimensional Dirac equation in the presence of a spatial confining point interaction exhibits a resonant behavior when one includes a weak electric field. After solving the Dirac equation in terms of parabolic cylinder functions and showing explicitly how the resonant behavior depends on the sign and strength of the electric field, we derive an approximate expression for the value of the resonance energy in terms of the electric field and delta interaction strength.Comment: 9 pages. To appear in Physics Letters