Exact theory for localized envelope modulated electrostatic wavepackets in space and dusty plasmas

Abundant evidence for the occurrence of modulated envelope plasma wave packets is provided by recent satellite missions. These excitations are characterized by a slowly varying localized envelope structure, embedding the fast carrier wave, which appears to be the result of strong modulation of the wave amplitude. This modulation may be due to parametric interactions between different modes or, simply, to the nonlinear (self-)interaction of the carrier wave. A generic exact theory is presented in this study, for the nonlinear self-modulation of known electrostatic plasma modes, by employing a collisionless fluid model. Both cold (zero-temperature) and warm fluid descriptions are discussed and the results are compared. The (moderately) nonlinear oscillation regime is investigated by applying a multiple scale technique. The calculation leads to a Nonlinear Schrodinger-type Equation (NLSE), which describes the evolution of the slowly varying wave amplitude in time and space. The NLSE admits localized envelope (solitary wave) solutions of bright(pulses) or dark- (holes, voids) type, whose characteristics (maximum amplitude, width) depend on intrinsic plasma parameters. Effects like amplitude perturbation obliqueness (with respect to the propagation direction), finite temperature and defect (dust) concentration are explicitly considered. Relevance with similar highly localized modulated wave structures observed during recent satellite missions is discussed.

Creation of persistent, straight, 2 mm long laser driven channels in underdense plasmas

The experimental study of the behavior of deuterium plasma with densities between 2 X 1018 and 2 x 10(20) cm(-3), subjected to a 6 TW, 30 ps, 3 X 10(18) W cm(-2) laser pulse, is presented Conclusive experimental proof that a single straight channel is generated when the laser pulse interacts with the lowest densities is provided This channel shows no small-scale longitudinal density modulations, extends up to 2 mm in length and persists for up to 150 ps after the peak of the interaction Bifurcation of the channel after 1 mm propagation distance is observed for the first time For higher density interactions, above the relativistic self-focusing threshold, bubblelike structures are observed to form at late times These observations have implications for both laser wakefield accelerators and fast ignition inertial fusion studies (C) 2010 American Institute of Physics [doi 10 1063/1 3505305]

Open Adoption: Adoptive Parents' Experiences of Birth Family Contact and Talking to Their Child about Adoption

The trend towards more open adoption presents adopters with unique parenting challenges associated with satisfying the child’s curiosity about their origins, and maintaining relationships with birth family through contact. This paper focuses on the experiences of 20 sets of adoptive parents who were interviewed as part of the Northern Ireland Care Pathways and Outcomes Study. Interviews were analysed following the principles of Interpretative Phenomenological Analysis (IPA). It explores adoptive parents’ experience of talking to their child about adoption, and of post-adoption contact with members of the birth family. Adopters discussed adoption sensitively with their child, but were concerned that difficult and complex family histories would present a risk to the child’s self-esteem and emotional well-being. All forms of contact proved emotionally and practically burdensome, however adopters were committed to making it work for the child’s benefit, and were open to increased contact should the child wish it in the future. There was little relationship with birth family outside of formal contact. The study reveals a need for a mechanism to facilitate communication with birth family if adopters are to be able to respond to the child’s changing need for contact and information.

Discharging not-for-profit accountability: UK charities and public discourse

Purpose: This paper aims to examine the accountability practices of large United Kingdom (UK) charities through public discourse.
Design/methodology/approach: Based on the ethical model of stakeholder theory, the paper develops a framework for classifying not-for-profit (NFP) accountability and analyzes the content of the annual reports and annual reviews of a sample of large UK charities using this framework.
Findings: The results suggest that contrary to the ethical model of stakeholder theory, the sample charities’ accountability practices are motivated by a desire to legitimize their activities and present their organizations’ activities in a positive light. These results contradict the raison d’eˆ tre of NFP organizations (NFPOs) and the values that they espouse. Research limitations/implications: Understanding the nature of accountability reporting in NFPOs has important implications for preparers and policy makers involved in furthering the NFP agenda. New research needs to examine shifts in accountability practices over time and assess the impact of the recent self-regulation developed to enhance sector accountability.
Originality/value: This paper contributes to the NFP accountability literature by: first, developing a framework of NFP accountability through public discourse using the ethical model of stakeholder theory; and second, advancing the understanding of the accountability practices of large UK charities.

Thick titanium dioxide films for semiconductor photocatalysis

Thick paste TiO2 films are prepared and tested for photocatalytic and photoinduced superhydrophilic (PSH) activity. The films are effective photocatalysts for the destruction of stearic acid using near or far UV and all the sol-gel films tested exhibited a quantum yield for this process of typically 0.15 %. These quantum yields are significantly greater (4-8-fold) than those for titania films produced by an APCVD technique, including the commercial self-cleaning glass product Activ(TM). The films are mechanically robust and optically clear and, as photocatalysts for stearic acid removal, are photochemically stable and reproducible. The kinetics of stearic acid photomineralisation are zero order with an activation energy of ca. 2.5 Kj mol(-1). All titania films tested, including those produced by APCVD, exhibit PSH. The light-induced fall, and dark recovery, in the water droplet contact angle made with titania paste films are similar in profile shape to those described by others for thin titania films produced by a traditional sol-gel route. (C) 2003 Elsevier Science B.V. All rights reserved.

Relativistic channeling of a picosecond laser pulse in a near-critical preformed plasma

Relativistic self-channeling of a picosecond laser pulse in a preformed plasma near critical density has been observed both experimentally and in 3D particle-in-cell simulations. Optical probing measurements indicate the formation of a single pulsating propagation channel, typically of about 5 mu m in diameter. The computational results reveal the importance in the channel formation of relativistic electrons traveling with the light pulse and of the corresponding self-generated magnetic field.

Prisons Memory Archive

Between 2006 and 2007, the Prisons Memory Archive (PMA) filmed participants, including former prisoners, prison staff, teachers, chaplains, visitors, solicitors and welfare workers back inside the Maze/Long Kesh Prison and Armagh Gaol. They shared the memory of the time spent in these prisons during the period of political violence from 1970 - 2000 in Northern Ireland, commonly known as the Troubles. Underpinning the overall methodology is co-ownership of the material, which gives participants the right to veto as well as to participate in the processes of editing and exhibiting their stories, so prioritising the value of co-authorship of their stories. The PMA adopted life-story interviewing techniques with the empty sites stimulating participants’ memory while they walked and talked their way around the empty sites. A third feature is inclusivity: the archive holds stories from across the full spectrum of the prison experience. A selection of the material, with accompanying context and links is available online www.prisonsmemoryarchive.com

Further Information:

The protocols of inclusivity, co-ownership and life-story telling make this collection significant as an initiative that engages with contemporary problems of how to negotiate narratives about a conflicted past in a society emerging out of violence. Inclusivity means that prison staff, prisoners, governors, chaplains, tutors and visitors have participated, relating their individual and collective experiences, which sit side by side on the PMA website. Co-ownership addresses the issues of ethics and sensitivity, allowing key constituencies to be involved. Life-story telling, based on oral history methodologies allows participants to be the authors of their own stories, crucial when dealing with sensitive issues from a violent past. The website hosts a selection of excerpts, e.g. the Armagh Stories page shows excerpts from 15 participants, while the Maze and Long Kesh Prison page offers interactive access to 24 participants from that prison. Using an interactive documentary structure, the site offers users opportunities to navigate their own way through the material and encourages them to hear and see the ‘other’, central to attempts at encouraging dialogue in a divided society. Further, public discussions have been held after screening of excerpts with community groups in the following locations - Belfast, Newtownabbey, Derry, Armagh, Enniskillen, London, Cork, Maynooth, Clones, and Monaghan. Extracts have been screened at international academic conferences in Valencia, Australia, Tartu, Estonia, Prague, and York. A dataset of the content, with description and links, is available for REF purposes.

Every Situation has its Rhythm: Acoustic Mimesis and Sonic Exoticism in Tambours Sur La Digue.

This article examines the soundscapes of Ariane Mnouchkine’s Tambours Sur La Digue and explores the concept of acoustic mimesis located in the performance as a dramaturgical strategy to create, aurally, an imagined Far East. In Tambours, mimesis is the performative principle exemplified by the presentation of the mise en scène, and most distinctly Mnouckine’s decision to adapt the Japanese performance tradition of Bunraku through a process of 'reversed' mimicry (in which human bodies simulate the wooden marionettes of the Japanese style). Mimesis pervades the acoustemologies of the performance as it is heard in the extracted sounds, styles, and rhythms of Asian musical modes and movements that consequently become dislocated from context; the sounds become imitated, iconicised and exoticised as sonic signatures as they reify the Orientalist spectacle. The 'oriental' soundscape, reverberating with exotic overtones, becomes the means by which the production creates an imaginary Orient – one in which the Orient Other is silenced, and is resounded only through the musical sensibilities of the Occidental Self.

Identifying optimal sites for natural recovery and restoration of impacted biogenic habitats in a special area of conservation using hydrodynamic and habitat suitability modelling

Selection of sites for successful restoration of impacted shellfish populations depends on understanding the dispersion capability and habitat requirements of the species involved. In Strangford Lough, Northern Ireland, the horse mussel (Modiolus modiolus) biogenic reefs cover only a fraction of their historical range with the remaining reefs badly damaged and requiring restoration. Previous experimental trials suggest that translocation of horse mussels accelerates reef recovery and has therefore been proposed as a suitable restoration technique. We used a series of coupled hydrodynamic and particle dispersal models to assess larval dispersion from remnant and translocated populations to identify suitable areas for adult live M. modiolus translocation in Strangford Lough, Northern Ireland. A maximum entropy model (MAXENT) was used to identify if dispersing larvae could reach habitat suitable for adult M. modiolus. From these we predicted if translocated mussels will reseed themselves or be able to act as larval sources for nearby reefs. The dispersal models showed that the remnant M. modiolus populations are largely self-recruiting with little connectivity between them. The majority of larvae settled near the sources and movement was largely dependent on the tides and not influenced by wind or waves. Higher reef elevation resulted in larvae being able to disperse further away from the release point. However, larval numbers away from the source population are likely to be too low for successful recruitment. There was also little connectivity between the Irish Sea and Strangford Lough as any larvae entering the Lough remained predominantly in the Strangford Narrows. The areas covered by these self-seeding populations are suitable for M. modiolus translocation according to the MAXENT model. As a result of this work and in conjunction with other field work we propose a combination of total protection of all remaining larval sources and small scale translocations onto suitable substrata in each of the identified self-recruiting areas.

High-capacity hydrogen and nitric oxide adsorption and storage in a metal-organic framework

Gas adsorption experiments have been carried out on a copper benzene tricarboxylate metal-organic framework material, HKUST-1. Hydrogen adsorption at 1 and 10 bar (both 77 K) gives an adsorption capacity of 11.16 mmol H-2 per g of HKUST-1 (22.7 mg g(-1), 2.27 wt %) at 1 bar and 18 mmol per g (36.28 mg g(-1), 3.6 wt %) at 10 bar. Adsorption of D-2 at 1 bar (77 K) is between 1.09 (at 1 bar) and 1.20(at < 100 mbar) times the H-2 values depending on the pressure, agreeing with the theoretical expectations. Gravimetric adsorption measurements of NO on HKUST-1 at 196 K (1 bar) gives a large adsorption capacity of similar to 9 mmol g(-1), which is significantly greater than any other adsorption capacity reported on a porous solid. At 298 K the adsorption capacity at 1 bar is just over 3 mmol g(-1). Infra red experiments show that the NO binds to the empty copper metal sites in HKUST-1. Chemiluminescence and platelet aggregometry experiments indicate that the amount of NO recovered on exposure of the resulting complex to water is enough to be biologically active, completely inhibiting platelet aggregation in platelet rich plasma.

RADIATIVE SIGNATURES OF RELATIVISTIC SHOCKS

Particle-in-cell simulations of relativistic, weakly magnetized collisionless shocks show that particles can gain energy by repeatedly crossing the shock front. This requires scattering off self-generated small length-scale magnetic fluctuations. The radiative signature of this first-order Fermi acceleration mechanism is important for models of both the prompt and afterglow emission in gamma-ray bursts and depends on the strength parameter a = lambda e/delta B/mc(2) of the fluctuations (lambda is the length scale and vertical bar delta B vertical bar is the magnitude of the fluctuations). For electrons (and positrons), acceleration saturates when the radiative losses produced by the scattering cannot be compensated by the energy gained on crossing the shock. We show that this sets an upper limit on both the electron Lorentz factor gamma <10(6) (n/1 cm(-3))(-1/6)(-1/6) and on the energy of the photons radiated during the scattering process h omega(max) <40Max(a, 1)(n/1 cm(-3))(1/6)(-1/6) eV, where n is the number density of the plasma and (gamma) over bar is the thermal Lorentz factor of the downstream plasma, provided a <a(crit) similar to 10(6). This rules out "jitter" radiation on self-excited fluctuations with a <I as a source of gamma rays, although high-energy photons might still be produced when the jitter photons are upscattered in an analog of the synchrotron self-Compton process. In fluctuations with a > 1, radiation is generated by the standard synchrotron mechanism, and the maximum photon energy rises linearly with a, until saturating at 70 MeV, when a = a(crit).

Facile Synthesis and Visualization of Janus Double-Brush Copolymers

Well-defined double-brush copolymers with each graft site carrying a polystyrene (PSt) graft and a polylactide (PLA) graft were synthesized by simultaneous reversible addition fragmentation chain transfer (RAFT) and ring-opening polymerization (ROP) processes, followed by ring-opening metathesis polymerization (ROMP) "grafting through" of the resulting diblock macromonomer (MM). Their Janus-type 1 morphologies were detected by transmission electron microscopy (TEM) imaging after thermal annealing to facilitate the intramolecular self-assembly of PSt and PLA grafts. This finding provides critical evidence to verify double-brush copolymers as Janus nanomaterials.

Dimensions of religious and national identity among Irish adolescents growing up in two jurisdictions

This poster explores the impact of growing up in different socio-political environments in the border areas of the Republic of Ireland (RoI) and Northern Ireland (NI) on adolescents’ evaluations of their religious and national identities. The vast majority of the population of the Republic of Ireland are Catholic and Irish whereas in Northern Ireland, the majority are Protestant and British. 713 adolescents (NI= 415; RoI=298), who categorised their religious identity as Catholic and their nationality as Irish completed the Collective Self – Esteem (CSE) scale (Crocker & Luhtanen, 1990) with reference to either their religious (N=350) or national identity (n=363). The overall rating of CSE for the Irish identity was significantly higher than the rating of CSE for the Catholic Identity. This result was modified by a significant interaction - adolescents in the Republic of Ireland rated the CSE of their Irish nationality higher than those in Northern Ireland (20.99 vs. 19.95), whereas adolescents in Northern Ireland rated the CSE of their Catholic religious identity higher than their peers in the Republic of Ireland (19.97 vs 18.87). Further analysis of the CSE subscales revealed differing patterns of relationships according to the scale. The evaluation of the Public Collective Self-Esteem of national and religious identities were significantly higher in the Republic of Ireland than in Northern Ireland, however Private Collective Self-esteem did not differ according to jurisdiction. These findings are discussed in relation to the social context and current theoretical accounts of collective identification processes.

They’re not racist…’ Prejudice denial, mitigation and suppression in dialogue

Social scientific work on the suppression, mitigation or denial of prejudiced attitudes has tended to focus on the strategic self-presentation and self-monitoring undertaken by individual social actors on their own behalf. In this paper, we argue that existing perspectives might usefully be extended to incorporate three additional considerations. First, that social actors may, on some occasions, act to defend not only themselves, but also others from charges of prejudice. Second, that over the course of any social encounter, interactants may take joint responsibility for policing conversation and for correcting and suppressing the articulation of prejudiced talk. Third, that a focus on the dialogic character of conversation affords an appreciation of the ways in which the status of any particular utterance, action or event as 'racist' or 'prejudiced' may constitute a social accomplishment. Finally, we note the logical corollary of these observations - that in everyday life, the occurrence of 'racist discourse' is likely to represent a collaborative accomplishment, the responsibility for which is shared jointly between the person of the speaker and those other co-present individuals who occasion, reinforce or simply fail to suppress it.

Trajectories of Learning Dispositions and Attitudes in Upper Primary Schools in Northern Ireland: What exactly is going on?

There is increasing research and policy interest in the importance of attitudes to learning, learning orientations and learning dispositions (however they are labelled), not only because they influence traditional measures of school achievement but also because they facilitate how well children function at school, with implications for their future learning. This paper reports the findings on pupils’ learning dispositions and attitudes from two separate cohorts of pupils as they progress through upper primary school (Key Stage 2) in 50 schools in Northern Ireland. (These data are drawn from two different longitudinal studies and the data collection period predates the introduction of the new Northern Ireland Curriculum.) Approximately 1200 pupils completed seven scales from the Assessment of Learner-Centred Practices, ALCPs (McCombs and Lauer, 1997) at three time points, at the end of P5 (9 year olds), at the end of P6 (10 years olds) and at the end of P7 (11 year olds). ALCPs draws on an extensive research base that has identified cognitive and motivational dispositions and attitudes that are associated with a positive orientation to learning, and ultimately with positive progress in school (Alexander and Murphy, 1998). Although each scale can be considered separately, the seven scales cluster into two groups: self-efficacy, mastery orientation, active learning strategies and curiosity are all predicted to be pro-learning; and challenge avoidance, work avoidance, and – to a lesser extent – performance orientation, are predicted to be negatively associated with learning. The general trajectory in the children’s self-evaluations shows that they are becoming less pro-learning over time, with significant decreases in their self-ratings of active learning, curiosity, mastery orientation and self-efficacy. At the same time, there is some evidence that they work harder and put more effort into their work but this is not accompanied by maintaining their previous pro-learning motivations and strategies. The pattern is consistently more negative for boys than for girls. There are very few differences between the two cohorts indicating that the pattern is not confined to a specific cohort. These findings are challenging and will be interrogated with regard to two questions – are the changes related to the influence of the children’s school experiences per se or are they more related to developmental differences as children adopt more critical appraisals of their personal attributes and efforts as they get older? Whatever the reason, these learning dispositions and attitudes are important as they contribute significantly to school achievement even when the more traditional predictors like gender and ability are taken into account.