Rate limit for photoassociation of a Bose-Einstein condensate

We simulate numerically the photodissociation of molecules into noncondensate atom pairs that accompanies photoassociation of an atomic Bose-Einstein condensate into a molecular condensate. Such rogue photodissociation sets a limit on the achievable rate of photoassociation. Given the atom density \rho and mass m, the limit is approximately 6\hbar\rho^{2/3}/m. At low temperatures this is a more stringent restriction than the unitary limit of scattering theory.Comment: 5 pgs, 18 refs., 3 figs., submitted to Phys. Rev. Let

Sub-Natural-Linewidth Quantum Interference Features Observed in Photoassociation of a Thermal Gas

By driving photoassociation transitions we form electronically excited molecules (Na$_2^*$) from ultra-cold (50-300 $\mu$K) Na atoms. Using a second laser to drive transitions from the excited state to a level in the molecular ground state, we are able to split the photoassociation line and observe features with a width smaller than the natural linewidth of the excited molecular state. The quantum interference which gives rise to this effect is analogous to that which leads to electromagnetically induced transparency in three level atomic $\Lambda$ systems, but here one of the ground states is a pair of free atoms while the other is a bound molecule. The linewidth is limited primarily by the finite temperature of the atoms.Comment: 4 pages, 5 figure

The incidence, severity, timing and circadian variation of hypophosphataemia in Glasgow Royal Infirmary Intensive Care Unit [poster]

No abstract available

The use and effectiveness of the eLib subject gateways: a preliminary investigation

Internet subject gateways were set up under the Electronic Libraries Programme (eLib) in order to address some of the problems of searching the Internet which have been identified by information professionals, i.e. locating relevant, good quality information. This preliminary study examines the extent to which academics in two universities use three eLib subject gateways (EEVL, OMNI and SOSIG). The results are generally encouraging for the eLib programme, but it is necessary for the gateways to be more effectively promoted. The study also found that academics do not have the same misgivings about the general search engines as the information professionals and seem to use them more readily than the gateways

Lecturer Attitudes Towards Teacher Trainees in a New South Wales College - 1955 and 1985

All who have worked in teacher education institutions for any length of time will know that significant changes have occurred in the way in which lecturers relate to their students and the sorts of behaviour which they expect from them. One hears lecturers speak of the good old days , especially when irritated by some particularly liberal student behaviour or some seemingly cavalier student attitude, but it would be unusual to find someone who genuinely believes that the old days were better than the new . It occurred to us that it would be an interesting exercise to look at some of the changes which have taken place in lecturer-student relationships over the years. We have chosen Armidale College of AdYanced Education as the subject of our discussion. simply because of our long association with it. No doubt, peculiarities of this College, especially in its residential aspects, would not apply to some other institutions but we feel that the general trends and directions we discuss will be common to all teacher education institutions in New South Wales and, quite possibly, to others throughout Australia. The year 1955, apart from being a neat thirty years (or one generation) from the present, also has a special significance. Both of us were at the College in that year, one as a lecturer and the other as a student. W\u27e have both been closely associated with it in one way or another ever since and the observations we make are based on first hand experience. In our discussion, we concentrate on four aspects of the past and present functioning of Armidale College. We examine each of these aspects in turn and then try to offer some possible explanations for the changes that have taken place over the last thirty years

Atom-molecule coherence in a one-dimensional system

We study a model of one-dimensional fermionic atoms that can bind in pairs to form bosonic molecules. We show that at low energy, a coherence develops between the molecule and fermion Luttinger liquids. At the same time, a gap opens in the spin excitation spectrum. The coherence implies that the order parameters for the molecular Bose-Einstein Condensation and the atomic BCS pairing become identical. Moreover, both bosonic and fermionic charge density wave correlations decay exponentially, in contrast with a usual Luttinger liquid. We exhibit a Luther-Emery point where the systems can be described in terms of noninteracting pseudofermions. At this point, we provide closed form expressions for the density-density response functions.Comment: 5 pages, no figures, Revtex 4; (v2) added a reference to cond-mat/0505681 where related results are reported; (v3) Expression of correlation functions given in terms of generalized hypergeometric function

Superposition of macroscopic numbers of atoms and molecules

We theoretically examine photoassociation of a non-ideal Bose-Einstein condensate, focusing on evidence for a macroscopic superposition of atoms and molecules. This problem raises an interest because, rather than two states of a given object, an atom-molecule system is a seemingly impossible macroscopic superposition of different objects. Nevertheless, photoassociation enables coherent intraparticle conversion, and we thereby propose a viable scheme for creating a superposition of a macroscopic number of atoms with a macroscopic number of molecules.Comment: 4 pages, 2 figs, to appear in Phys. Rev. Let

The incidence, severity, timing and circadian variation of hypophosphataemia in Glasgow Royal Infirmary Intensive Care Unit [poster]

No abstract available

Comparison of acquired activated protein C resistance, using the CAT and ST-genesia® analysers and three thrombin generation methods, in APS and SLE patients

Background: Acquired activated protein C resistance (APCr) has been identified in antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE). Objective: To assess agreement between the ST-Genesia® and CAT analysers in identifying APCr prevalence in APS/SLE patients, using three thrombin generation (TG) methods. Methods: APCr was assessed with the ST- Genesia using STG-ThromboScreen and with the CAT using recombinant human activated protein C and Protac® in 105 APS, 53 SLE patients and 36 thrombotic controls. Agreement was expressed in % and by Cohenʹs kappa coefficient. Results: APCr values were consistently lower with the ST- Genesia® compared to the CAT, using either method, in both APS and SLE patients. Agreement between the two analysers in identifying APS and SLE patients with APCr was poor (≤65.9%, ≤0.20) or fair (≤68.5%, ≥0.29), regardless of TG method, respectively; no agreement was observed in thrombotic controls. APCr with both the ST Genesia and the CAT using Protac®, but not the CAT using rhAPC, was significantly greater in triple antiphospholipid antibody (aPL) APS patients compared to double/single aPL patients (p <0.04) and in thrombotic SLE patients compared to non-thrombotic SLE patients (p < 0.05). Notably, the ST-Genesia®, unlike the CAT, with either method, identified significantly greater APCr in pregnancy morbidity (median, confidence intervals; 36.9%, 21.9–49.0%) compared to thrombotic (45.7%, 39.6–55.5%) APS patients (p = 0.03). Conclusion: Despite the broadly similar methodology used by CAT and ST-Genesia®, agreement in APCr was poor/fair, with results not being interchangeable. This may reflect differences in the TG method, use of different reagents, and analyser data handling