Spin 1 inversion: a Majorana tensor force for deuteron alpha scattering

We demonstrate, for the first time, successful S-matrix to potential inversion for spin one projectiles with non-diagonal $S^j_{ll'}$ yielding a $T_{\rm R}$ interaction. The method is a generalization of the iterative-perturbative, IP, method. We present a test case indicating the degree of uniqueness of the potential. The method is adapted, using established procedures, into direct observable to potential inversion, fitting $\sigma$, ${\rm i}T_{11}$, $T_{20}$, $T_{21}$ and $T_{22}$ for d + alpha scattering over a range of energies near 10 MeV. The $T_{\rm R}$ interaction which we find is very different from that proposed elsewhere, both real and imaginary parts being very different for odd and even parity channels.Comment: 7 pages Revtex, 4 ps figure

Strongly-resonant p-wave superfluids

We study theoretically a dilute gas of identical fermions interacting via a p-wave resonance. We show that, depending on the microscopic physics, there are two distinct regimes of p-wave resonant superfluids, which we term "weak" and "strong". Although expected naively to form a BCS-BEC superfluid, a strongly-resonant p-wave superfluid is in fact unstable towards the formation of a gas of fermionic triplets. We examine this instability and estimate the lifetime of the p-wave molecules due to the collisional relaxation into triplets. We discuss consequences for the experimental achievement of p-wave superfluids in both weakly- and strongly-resonant regimes

Structure and consequences of vortex-core states in p-wave superfluids

It is now well established that in two-dimensional chiral p-wave paired superfluids, the vortices carry zero-energy modes which obey non-abelian exchange statistics and can potentially be used for topological quantum computation. In such superfluids there may also exist other excitations below the bulk gap inside the cores of vortices. We study the properties of these subgap states, and argue that their presence affects the topological protection of the zero modes. In conventional superconductors where the chemical potential is of the order of the Fermi energy of a non-interacting Fermi gas, there is a large number of subgap states and the mini-gap towards the lowest of these states is a small fraction of the Fermi energy. It is therefore difficult to cool the system to below the mini-gap and at experimentally available temperatures, transitions between the subgap states, including the zero modes, will occur and can alter the quantum states of the zero-modes. We show that compound qubits involving the zero-modes and the parity of the occupation number of the subgap states on each vortex are still well defined. However, practical schemes taking into account all subgap states would nonetheless be difficult to achieve. We propose to avoid this difficulty by working in the regime of small chemical potential mu, near the transition to a strongly paired phase, where the number of subgap states is reduced. We develop the theory to describe this regime of strong pairing interactions and we show how the subgap states are ultimately absorbed into the bulk gap. Since the bulk gap vanishes as mu -> 0 there is an optimum value mu_c which maximises the combined gap. We propose cold atomic gases as candidate systems where the regime of strong interactions can be explored, and explicitly evaluate mu_c in a Feshbach resonant K-40 gas.Comment: 19 pages, 10 figures; v2: main text as published version, additional detail included as appendice

Effects of organic and ‘low input’ production methods on food quality and safety

The intensification of agricultural production in the last century has resulted in a significant loss of biodiversity, environmental problems and associated societal costs. The use of shorter rotations or monocropping and high levels of mineral fertilisers, pesticides and crop growth regulators may also have had negative impacts on food quality and safety. To reverse the negative environmental and biodiversity impacts of agricultural intensification, a range of different ‘low input’ farming systems have been developed and are now supported by EU and government support schemes. A range of recent reviews concluded that switching to low input, integrated or organic farming practices results in significant environmental benefits and increased biodiversity in agro-ecosystems. Some recent studies also reported higher levels of nutritionally desirable compounds (e.g. vitamins, antioxidants, mineral nutrients) in foods from organic and ‘low input’ production systems compared to food from conventional systems. The increasing demand and current price premiums achieved by foods from low input and especially organic production systems were shown to be closely linked to consumer perceptions about nutritional and health benefits of such foods. However, there are other studies reporting no significant differences in composition between low input and conventional foods, or inconsistent results. There is currently a lack of (a) factorial studies, which allow the effect of individual production system components (e.g. rotation design, fertility management, crop health management, variety choice) on food composition to be assessed and (b) dietary intervention or cohort studies which compare the effect of consuming foods from different production systems on animal and/or human health. It is therefore currently not possible to draw overall conclusions about the effect of low input production on food quality and safety. This paper will (a) describe the range of organic and other ‘low input’ standards, certification and support systems currently used, (b) summarise the currently available information on effects of organic and other low input crop production systems on the environment, biodiversity and food quality, and (c) describe the methodologies and results from subproject 2 of the EU-funded Integrated project QualityLowInputFood. This project focused on improving our knowledge about the effect of organic and low input crop and livestock production systems on food quality and safety parameters

Stable Topological Superfluid Phase of Ultracold Polar Fermionic Molecules

We show that single-component fermionic polar molecules confined to a 2D geometry and dressed by a microwave field, may acquire an attractive $1/r^3$ dipole-dipole interaction leading to superfluid p-wave pairing at sufficiently low temperatures even in the BCS regime. The emerging state is the topological $p_x+ip_y$ phase promising for topologically protected quantum information processing. The main decay channel is via collisional transitions to dressed states with lower energies and is rather slow, setting a lifetime of the order of seconds at 2D densities $\sim 10^8$ cm$^{-2}$

Exact factorization of the time-dependent electron-nuclear wavefunction

We present an exact decomposition of the complete wavefunction for a system of nuclei and electrons evolving in a time-dependent external potential. We derive formally exact equations for the nuclear and electronic wavefunctions that lead to rigorous definitions of a time-dependent potential energy surface (TDPES) and a time-dependent geometric phase. For the $H_2^+$ molecular ion exposed to a laser field, the TDPES proves to be a useful interpretive tool to identify different mechanisms of dissociation.Comment: 4 pages, 2 figure

Retrospective studies of operating problems in air transport

An epidemiological model for the study of human errors in aviation is presented. In this approach, retrospective data are used as the basis for formulation of hypotheses as to system factors which may have contributed to such errors. Prospective experimental studies of aviation operations are also required in order to prove or disprove the hypotheses, and to evaluate the effectiveness of intervention techniques designed to solve operational problems in the aviation system

A survey of the status of and philosophies relating to cockpit warning systems

A survey was taken to study current cockpit caution and warning (c/w) systems, and to examine industry philosophies regarding c/w system design including current efforts to improve them. Guidelines currently in use were outlined and those which appear to have general acceptance, those which are considered ineffective or erroneous, and those with which there is broad disagreement as to validity, were delineated. Major airplane manufacturerd were surveyed and a manufacturer dealing specifically with aircraft instrumentation was consulted