Atoms in microcavities : detection and spectroscopy

This thesis presents work undertaken with cold rubidium atoms interacting with an optical microcavity. The optical microcavity used is unique in its design, being formed between an optical fibre and silicon micromirror. This allows direct optical access to the cavity mode, whilst the use of microfabrication techniques in the design means that elements of the system are inherently scalable. In addition, the parameters of the system are such that a single atom has a substantial impact on the cavity field. In this system, two types of signal arise from the atoms' interaction with the cavity field; a `reflection' signal and a `fluorescence' signal. A theoretical description for these signals is presented, followed by experiments which characterise the signals under a variety of experimental conditions. The thesis then explores two areas: the use of the microcavity signals for atom detection and the investigation of how higher atom numbers and, as a result, a larger cooperative interaction between the atoms and the cavity field, impacts the signals. First, the use of these signals to detect an effective single atom and individual atoms whilst falling and trapped is explored. The effectiveness of detection is parameterised in terms of detection confidence and signal to noise ratio, detection fidelity and dynamic range. In the second part of this thesis, the effect of higher atom numbers on the reflection and fluorescence signals is investigated. A method for increasing the atom number is presented, alongside experiments investigating the impact on the measured signals. This is followed by experiments which explore the dispersive nature of the atom-cavity interaction by measuring the excitation spectrum of the system in reflection and fluorescence. In doing so, it is shown that, for weak coupling, these two signals are manifestly different

The current distribution of signal and native crayfish in the Broadmead Brook, Wiltshire

Signal crayfish (Pacifastacus leniusculus) have existed in the upper reaches of Broadmead Brook in Wiltshire since 200 individuals were introduced at West Kington in 1981. The population has expanded upstream and downstream since this introduction, however, giving rise to concerns that it may potentially threaten the native crayfish population further downstream. Signal crayfish can act as a vector of crayfish plague - a disease caused by the fungus Aphanomyces astaci Schikora which results in almost complete mortality to the native, white-clawed crayfish Austropotamobius pallipes. The native crayfish in Broadmead Brook have not yet succumbed to crayfish plague and are currently free of the disease. However, as signal crayfish appear to out-compete the native species, the native population could still be under threat. In this article, we highlight the findings of previous crayfish surveys on Broadmead Brook and describe work undertaken in summer 2001 to map the current distribution of native and signal crayfish. Finally, options for controlling the spread of signal crayfish are discussed

Goodbye Polsko, Hello Anglio

Joanna Czechowska Speaks with Joanna KosmalskaThis interview is part of a literature project DEC-2011/01/B/HS2/05120 financed by the National Science Centre

Cynicism Starts Young: Age and Entrepreneurship over Transition

Studies of self-employment determinants in developed market economies comprise the effects of business cycle, changing social structures or legal framework, industrial organization regulations and government policies. This paper contributes to the literature by analysing the cyclical patterns of self-employment determinants taking into account both the trends associated with the transition and the variability induced by economic and labour market fluctuations. We construct a consistent panel of entrepreneurship choice models based on consecutive quarterly labour force surveys for Poland - a country with nearly highest self-employment rates in CEECs and the EU - across the time span 1995q1-2008q4 and trace changes in the marginal effects estimators. We find that the notion of self-employment as survival strategy emphasised previously in the literature exhibits stronger in the periods of the labour market contraction. We also demonstrate that young university graduates prefer wage employment to entrepreneurship.self-employment, transition, cyclicality, selection models

Native Birth: Identity and Territory in Postcolonial Guinea-Bissau, West Africa

Author's final manuscript

Hedging China? The Meaning of the ASEAN Member States’ Interests in Forging their Policies Towards China

Rozdział z: The Quandaries and Foreign Development, ed. D. Mierzejewski, “Contemporary Asian Studies Series

Positive harmonic functions on comb-like domains

This paper investigates positive harmonic functions on a domain which contains an infinite cylinder, and whose boundary is contained in the union of parallel hyperplanes. (In the plane its boundary consists of two sets of vertical semi-infinite lines.) It characterizes, in terms of the spacing between the hyperplanes, those domains for which there exist minimal harmonic functions with a certain exponential growth.Comment: 18 page

Measurement of the double longitudinal spin asymmetry in inclusive jet production in polarized p+p collisions at sqrt(s) = 200 GeV

We present preliminary results for the first measurements of the double longitudinal spin asymmetry A_LL in inclusive jet production at mid-rapidity in polarized proton-proton collisions at sqrt(s) = 200 GeV. The data amount to ~ 0.5 pb-1 collected at RHIC in 2003 and 2004 with beam polarizations up to 45%. The jet transverse energies are in the range of 5 < pT < 17 GeV/c. The data are consistent with theoretical evaluations using deep-inelastic scattering parametrizations for gluon polarization in the nucleon, and tend to disfavor large positive values of gluon polarization.Comment: 4 pages, 1 figure. To appear in the proceedings of the Particles and Nuclei International Conference (PANIC05), October 24-28, 2005 Santa Fe, NM, USA; Corrected figur