Feminists really do count : the complexity of feminist methodologies

We are delighted to be presenting this special issue on the topic of feminism and quantitative methods. We believe that such an issue is exceptionally timely. This is not simply because of ongoing debates around quantification within the field of feminism and women‟s studies. It is also because of debates within the wider research community about the development of appropriate methodologies that take account of new technological and philosophical concerns and are fit-for-purpose for researching contemporary social, philosophical, cultural and global issues. Two areas serve as exemplars in this respect and both speak to these combined wider social science and specifically feminist methodological concerns. The first is the increasing concern amongst social scientists with how the complexity of social life can be captured and analysed. Within feminism, this can be seen in debates about intersectionality that recognise the concerns arising from multiple social positions/divisions and associated power issues. As Denis (2008: 688) comments in respect of intersectional analysis „The challenge of integrating multiple, concurrent, yet often contradictory social locations into analyses of power relations has been issued. Theorising to accomplish this end is evolving, and we are struggling to develop effective methodological tools in order to marry theorising with necessary complex analyses of empirical data.‟ Secondly, new techniques and new data sources are now coming on line. This includes work in the UK of the ESRC National Data Strategy which has been setting out the priorities for the development of research data resources both within and across the boundaries of the social sciences. This will facilitate historical, longitudinal, interdisciplinary and mixed methodological research. And it may be the case that these developments facilitate the achievement of a longstanding feminist aim not simply for interdisciplinarity but for transdisciplinarity in epistemological and methodological terms

Quantum-degenerate mixture of fermionic lithium and bosonic rubidium gases

We report on the observation of sympathetic cooling of a cloud of fermionic 6-Li atoms which are thermally coupled to evaporatively cooled bosonic 87-Rb. Using this technique we obtain a mixture of quantum-degenerate gases, where the Rb cloud is colder than the critical temperature for Bose-Einstein condensation and the Li cloud colder than the Fermi temperature. From measurements of the thermalization velocity we estimate the interspecies s-wave triplet scattering length |a_s|=20_{-6}^{+9} a_B. We found that the presence of residual rubidium atoms in the |2,1> and the |1,-1> Zeeman substates gives rise to important losses due to inelastic collisions.Comment: 4 pages, 3 figure

Creation and manipulation of Feshbach resonances with radio-frequency radiation

We present a simple technique for studying collisions of ultracold atoms in the presence of a magnetic field and radio-frequency radiation (rf). Resonant control of scattering properties can be achieved by using rf to couple a colliding pair of atoms to a bound state. We show, using the example of 6Li, that in some ranges of rf frequency and magnetic field this can be done without giving rise to losses. We also show that halo molecules of large spatial extent require much less rf power than deeply bound states. Another way to exert resonant control is with a set of rf-coupled bound states, linked to the colliding pair through the molecular interactions that give rise to magnetically tunable Feshbach resonances. This was recently demonstrated for 87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the underlying atomic and molecular physics which made this possible. Lastly, we consider the control that may be exerted over atomic collisions by placing atoms in superpositions of Zeeman states, and suggest that it could be useful where small changes in scattering length are required. We suggest other species for which rf and magnetic field control could together provide a useful tuning mechanism.Comment: 21 pages, 8 figures, submitted to New Journal of Physic

Feshbach spectroscopy and analysis of the interaction potentials of ultracold sodium

We have studied magnetic Feshbach resonances in an ultracold sample of Na prepared in the absolute hyperfine ground state. We report on the observation of three s-, eight d-, and three g-wave Feshbach resonances, including a more precise determination of two known s-wave resonances, and one s-wave resonance at a magnetic field exceeding 200mT. Using a coupled-channels calculation we have improved the sodium ground-state potentials by taking into account these new experimental data, and derived values for the scattering lengths. In addition, a description of the molecular states leading to the Feshbach resonances in terms of the asymptotic-bound-state model is presented.Comment: 11 pages, 4 figure

Photoassociation spectroscopy of cold alkaline earth atoms near the intercombination line

The properties of photoassociation (PA) spectra near the intercombination line (the weak transition between $^{1}S_{0}$ and $^{3}P_{1}$ states) of group II atoms are theoretically investigated. As an example we have carried out a calculation for Calcium atoms colliding at ultra low temperatures of 1 mK, 1 $\mu$K, and 1 nK. Unlike in most current photoassociation spectroscopy the Doppler effect can significantly affect the shape of the investigated lines. Spectra are obtained using Ca--Ca and Ca--Ca$^*$ short-range {\it ab initio} potentials and long-range van der Waals and resonance dipole potentials. The similar van der Waals coefficients of ground $^{1}S_{0} + ^{1}S_{0}$ and excited $^{1}S_{0} + ^{3}P_{1}$ states cause the PA to differ greatly from those of strong, allowed transitions with resonant dipole interactions. The density of spectral lines is lower, the Condon points are at relatively short range, and the reflection approximation for the Franck-Condon factors is not applicable, and the spontaneous decay to bound ground-state molecules is efficient. Finally, the possibility of efficient production of cold molecules is discussed

Service Platform for Converged Interactive Broadband Broadcast and Cellular Wireless

A converged broadcast and telecommunication service platform is presented that is able to create, deliver, and manage interactive, multimedia content and services for consumption on three different terminal types. The motivations of service providers for designing converged interactive multimedia services, which are crafted for their individual requirements, are investigated. The overall design of the system is presented with particular emphasis placed on the operational features of each of the sub-systems, the flows of media and metadata through the sub-systems and the formats and protocols required for inter-communication between them. The key features of tools required for creating converged interactive multimedia content for a range of different end-user terminal types are examined. Finally possible enhancements to this system are discussed. This study is of particular interest to those organizations currently conducting trials and commercial launches of DVB-H services because it provides them with an insight of the various additional functions required in the service provisioning platforms to provide fully interactive services to a range of different mobile terminal types

Atom-molecule equilibration in a degenerate Fermi gas with resonant interactions

We present a nonequilibrium kinetic theory describing atom-molecule population dynamics in a two-component Fermi gas with a Feshbach resonance. Key collision integrals emerge that govern the relaxation of the atom-molecule mixture to chemical and thermal equilibrium. Our focus is on the pseudogap regime where molecules form above the superfluid transition temperature. In this regime, we formulate a simple model for the atom-molecule population dynamics. The model predicts the saturation of molecule formation that has been observed in recent experiments, and indicates that a dramatic enhancement of the atom-molecule conversion efficiency occurs at low temperatures.Comment: Updated manuscript on July 5, 2004. Four pages with three embedded figure

Laser Intensity Dependence of Photoassociation in Ultracold Metastable Helium

Photoassociation of spin-polarized metastable helium to the three lowest rovibrational levels of the J=1, $0_u^+$ state asymptoting to 2$s {}^{3}$S$_{1}+2p {}^{3}$P$_{0}$ is studied using a second-order perturbative treatment of the line shifts valid for low laser intensities, and two variants of a non-perturbative close-coupled treatment, one based upon dressed states of the matter plus laser system, and the other on a modified radiative coupling which vanishes asymptotically, thus simulating experimental conditions. These non-perturbative treatments are valid for arbitrary laser intensities and yield the complete photoassociation resonance profile. Both variants give nearly identical results for the line shifts and widths of the resonances and show that their dependence upon laser intensity is very close to linear and quadratic respectively for the two lowest levels. The resonance profiles are superimposed upon a significant background loss, a feature for this metastable helium system not present in studies of photoassociation in other systems, which is due to the very shallow nature of the excited state $0_u^+$ potential. The results for the line shifts from the close-coupled and perturbative calculations agree very closely at low laser intensities.Comment: 14 pages, 7 figures, title altered, text reduce

Clinical characterization of 66 patients with congenital retinal disease due to the deep-intronic c.2991+1655A>G mutation in CEP290

Purpose: To describe the phenotypic spectrum of retinal disease caused by the c.2991+1655A>G mutation in CEP290 and to compare disease severity between homozygous and compound heterozygous patients. Methods: Medical records were reviewed for best-corrected visual acuity (BCVA), age of onset, fundoscopy descriptions. Foveal outer nuclear layer (ONL) and ellipsoid zone (EZ) presence was assessed using spectral-domain optical coherence tomography (SD-OCT). Differences between compound heterozygous and homozygous patients were analyzed based on visual performance and visual development. Results: A total of 66 patients were included. The majority of patients had either light perception or no light perception. In the remaining group of 14 patients, median BCVA was 20/195 Snellen (0.99 LogMAR; range 0.12-1.90) for the right eye, and 20/148 Snellen (0.87 LogMAR; range 0.22-1.90) for the left. Homozygous patients tended to be more likely to develop light perception compared to more severely affected compound heterozygous patients (P = 0.080) and are more likely to improve from no light perception to light perception (P = 0.022) before the age of 6 years. OCT data were available in 12 patients, 11 of whom had retained foveal ONL and EZ integrity up to 48 years (median 23 years) of age. Conclusions: Homozygous patients seem less severely affected compared to their compound-heterozygous peers. Improvement of visual function may occur in the early years of life, suggesting a time window for therapeutic intervention up to the approximate age of 17 years. This period may be extended by an intact foveal ONL and EZ on OCT

Interfering Doorway States and Giant Resonances. II: Transition Strengths

The mixing of the doorway components of a giant resonance (GR) due to the interaction via common decay channels influences significantly the distribution of the multipole strength and the energy spectrum of the decay products of the GR. The concept of the partial widths of a GR becomes ambiguous when the mixing is strong. In this case, the partial widths determined in terms of the $K$- and $S$-matrices must be distinguished. The photoemission turns out to be most sensitive to the overlapping of the doorway states. At high excitation energies, the interference between the doorway states leads to a restructuring towards lower energies and apparent quenching of the dipole strength.Comment: 17 pages, LaTeX, 5 figures as JPEG, to appear in PRC (July 1997