Social behaviour of Jackass penguins at sea

This paper reports flocking, communal feeding and other aspects of sea-based social behaviour in the jackass penguin (Spheniscus demersus). Penguins tend to occur within about 15 km of the mainland, but range farther afield from the islands used for breeding and/or roosting. Relatively large groups of 50 and more birds occur more than 50 km from the nearest island, but seldom more than 15 km from the mainland. The majority of the sea-going population consists of birds occurring in groups. Mean group size is eight birds. In any one particular group the members all tend to perform the same behaviour at the same time. The tendency to form foraging groups and the highly synchronized diving and cohesion of these groups indicate that this behaviour is socially facilitated, suggesting that it is adaptive in terms of both enhanced prey location and capture. Feeding penguins do not submerge for long and do not dive deeply. Birds in diving groups perform head-dipping movements which might signal readiness to dive and thus promote synchronous activity. The paper points out how little is known about jackass penguins at sea - the environment in which they probably spend the majority of their time. Lack of information on the birds at sea precludes proper interpretation of many land-based events attending the biology of the bird and its conservation

Correlation structure in nondipole photoionization

The nondipole parameters that characterize the angular disribution of the photoelectrons from the 3d subshell of Cs are found to be altered qualitatively by the inclusion of correlation in the form of interchannel coupling between the $3d_{3/2}$ and $3d_{5/2}$ photoionization channels. A prominent characteristic maximum is predicted only in the parameters for $3d_{5/2}$ photoionization, while the effect for $3d_{3/2}$ is rather weak. The results are obtained within the framework of the Generalized Random Phase Approximation with Exchange (GRPAE), which in addition to the RPAE effects takes into account the rearrangement of all atomic electrons due to the creation of a 3d vacancy

Cladoceran birth and death rates estimates

I. Birth and death rates of natural cladoceran populations cannot be measured directly. Estimates of these population parameters must be calculated using methods that make assumptions about the form of population growth. These methods generally assume that the population has a stable age distribution. 2. To assess the effect of variable age distributions, we tested six egg ratio methods for estimating birth and death rates with data from thirty-seven laboratory populations of Daphnia pulicaria. The populations were grown under constant conditions, but the initial age distributions and egg ratios of the populations varied. Actual death rates were virtually zero, so the difference between the estimated and actual death rates measured the error in both birth and death rate estimates. 3. The results demonstrate that unstable population structures may produce large errors in the birth and death rates estimated by any of these methods. Among the methods tested, Taylor and Slatkin's formula and Paloheimo's formula were most reliable for the experimental data. 4. Further analyses of three of the methods were made using computer simulations of growth of age-structured populations with initially unstable age distributions. These analyses show that the time interval between sampling strongly influences the reliability of birth and death rate estimates. At a sampling interval of 2.5 days (equal to the duration of the egg stage), Paloheimo's formula was most accurate. At longer intervals (7.5–10 days), Taylor and Slatkin's formula which includes information on population structure was most accurate

‘Stumbling through’? Relationship-based social work practice in austere times

In recent times relationship-based practice has become a familiar term in social work practice and education. Despite its widespread adoption, how relationship-based practice is understood varies widely. Drawing on contemporary conceptualisations of the child and family and individuals as psychosocial subjects experiencing social suffering, this paper explores how current social work practice can be understood in the context of neoliberalism and austerity. Setting these ideas in an historical context helps to inform our understanding as to why social work seems to be the focus of sustained political discontent and scrutiny, making it difficult to retain a balanced relationship-based professional stance. Contemporary responses to the current challenges of everyday practice are outlined and the contribution of psychodynamic and systemic ideas to promoting relationship-based practice is explored. The paper concludes by considering how the concept of social systems as defences against anxiety can inform our understanding of the resistance amongst practitioners to relationship-based practice and emphasises the importance of reflective spaces and places for developing and maintaining integrated, mature relational approaches to practice which impact on practice at both the individual casework and social structural level

Eureka and beyond: mining's impact on African urbanisation

This collection brings separate literatures on mining and urbanisation together at a time when both artisanal and large-scale mining are expanding in many African economies. While much has been written about contestation over land and mineral rights, the impact of mining on settlement, notably its catalytic and fluctuating effects on migration and urban growth, has been largely ignored. African nation-states’ urbanisation trends have shown considerable variation over the past half century. The current surge in ‘new’ mining countries and the slow-down in ‘old’ mining countries are generating some remarkable settlement patterns and welfare outcomes. Presently, the African continent is a laboratory of national mining experiences. This special issue on African mining and urbanisation encompasses a wide cross-section of country case studies: beginning with the historical experiences of mining in Southern Africa (South Africa, Zambia, Zimbabwe), followed by more recent mineralizing trends in comparatively new mineral-producing countries (Tanzania) and an established West African gold producer (Ghana), before turning to the influence of conflict minerals (Angola, the Democratic Republic of Congo and Sierra Leone)

Crystal chemistry search of multiferroics with the stereochemically active lone pair

On the basis of our previous studies of magnetoelectric ordering of BiFeO3, TbMnO3, TbMn2O5 and BiMn2O5 we formulate the crystal chemistry criteria for the search of multiferroics and reveal potential multiferroics Pb2Cu(OH)4Cl2, Pb5Cr3F19, Mn(SeO3){\dot}H2O and BiPbSr2MnO6 each containing the ion with a lone pair.Comment: 4 pages, 8 figures,submitted to J Supercond Nov Mag

Relativistic calculation of nuclear transparency in (e,e'p) reactions

Nuclear transparency in (e,e'p) reactions is evaluated in a fully relativistic distorted wave impulse approximation model. The relativistic mean field theory is used for the bound state and the Pauli reduction for the scattering state, which is calculated from a relativistic optical potential. Results for selected nuclei are displayed in a Q^2 range between 0.3 and 1.8 (GeV/c)^2 and compared with recent electron scattering data. For Q^2 = 0.3 (GeV/c)^2 the results are lower than data; for higher Q^2 they are in reasonable agreement with data. The sensitivity of the model to different prescriptions for the one-body current operator is investigated. The off-shell ambiguities are rather large for the distorted cross sections and small for the plane wave cross sections.Comment: 8 pages, 3 figure

D* Production in Deep Inelastic Scattering at HERA

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+$ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.Comment: 17 pages including 4 figure