bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adverse effects of ivermectin on the dung beetles,Caccobius jessoensisHarold, and rare species,Copris ochusMotschulsky andCopris acutidensMotschulsky (Coleoptera: Scarabaeidae), in Japan
Authors: Iwasa M. , Maruo T. , Ueda M. , Yamashita N. 
Published: November 2007

AbstractEffects of the antiparasitic drug, ivermectin, on the dung beetles,Caccobius jessoensisHarold, 1867 and the rare species,Copris ochusMotschulsky, 1860 andCopris acutidensMotschulsky, 1860 were studied in laboratory and field experiments in Hokkaido, Japan. Ivermectin was detected in dung from 1 to 21 or 28 days following treatment, with a peak on the first day after treatment in two pour-on administrations (500 μg kg−1), although there were considerable differences between the two peaks. InC. jessoensis, brood balls constructed by the female were not reduced in the dung of treated cattle except for seven days after treatment in experiment 2. Also, there was no significant difference in the mean weight of brood balls between dung from treated and control cattle. However, the emergence rates were significantly reduced in dung 1–3 days after treatment. In the field study, brood balls constructed byC. jessoensiswere more abundant in dung from treated cattle in experiment 1, but adult emergence was significantly reduced at one and seven days after treatments. Adult mortality ofC. ochusMotschulsky at 90 days after the beginning of rearing was 11.1% in dung from control cattle with 22 brood balls constructed, whereas it was 84% in dung from treated cattle with no brood balls and/or ovipositioning. Also, inC. acutidensMotschulsky, adult mortality at 90 days after the beginning of rearing was 3.6% in dung from control cattle with 13 brood balls constructed, whereas it was 94.1% in dung from treated cattle with no brood balls or ovipositioning. The environmental risk in the use of ivermectin during breeding period of dung beetles in pasture is discussed.
Influence of habitat pattern on orientation during host fruit location in the tomato fruit fly,Neoceratitis cyanescens
Authors: Brévault T. , Quilici S. 
Published: November 2007

AbstractFruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly,Neoceratitis cyanescens(Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.
Dieback and recovery in poplar and attack by the hornet clearwing moth, Sesia apiformis (Clerck) (Lepidoptera: Sesiidae)
Authors: Straw N.A. , Green G. , Williams D.T. 
Published: November 2007

AbstractA survey of 801 poplar trees in central east England in 1999 demonstrated a correlation between crown dieback and infestation by hornet clearwing moth (Sesia apiformis), induced by a period of drought in 1995–1996. To determine whether trees colonised by S. apiformis would subsequently deteriorate and die or whether they could recover despite infestation and damage to the stem, all trees in the original survey were re-assessed in 2001, 2003 and 2005. The repeat surveys showed that trees with 70% or less crown dieback in 1999 replaced their canopy and generally improved by 2005, irrespective of the numbers of S. apiformis in the stem, whereas trees that had 75% or more crown dieback in 1999 either died or declined further. The presence of S. apiformis did not prevent tree recovery, and there was little evidence that infestation slowed the rate of recovery. Populations of S. apiformis, measured in terms of the numbers of adult emergence holes visible in the base of the trees, decreased between 2001 and 2005 at the same time as the amount of dieback visible in the canopy of the poplars markedly decreased. However, the fall in numbers of emergence holes at this time reflected a decline in larval establishment 2–3 years earlier, and indicated that the moth population had responded to a more rapid restoration in the internal state of the trees, which was not reflected immediately by the gradual replacement of dead branches and reduction in dieback symptoms.
Ladybird egg cluster size: relationships between species, oviposition substrate and cannibalism
Authors: Timms J.E.L. , Leather S.R. 
Published: November 2007

AbstractThe success or not of ladybirds as biological control agents is dependent on both their foraging behaviour and their individual survival rates. The former is a function of the habitats they utilise; the latter, a consequence of their reproductive strategy. Egg clustering was investigated in two ladybird species, Aphidecta obliterata, a conifer specialist, and Adalia bipunctata, an arboreal woodland generalist. The effect of oviposition substrate (filter papers vs. spruce needles) on clutch size and oviposition preference was also tested. Adalia bipunctata laid significantly more eggs than A. obliterata. The size of egg clusters laid by the two coccinellids varied between species and substrate types. Adalia bipunctata laid larger egg clusters than A. obliterata, with batches reaching a maximum size of 32 eggs on spruce and 41 eggs on paper, while those of A. obliterata contained a maximum of 5 eggs on spruce and 9 eggs on paper. Of the clusters laid by A. obliterata, 18.6% of those on paper and 21.4% of those on spruce contained only a single egg, whereas a minimum of two eggs per cluster were laid by A. bipunctata. Smaller clusters were laid on the spruce cuttings by both species when compared with those laid on the filter paper, but A. obliterata laid significantly more eggs on spruce than on the filter paper (77% vs. 23%), whilst A. bipunctata laid significantly more eggs on the filter paper (91%). It is suggested that coccinellid eggs are more likely to be washed off spruce needles than broad leaves and that, by laying smaller egg clusters on spruce, A. obliterata reduces this risk. Adalia bipunctata usually lays its eggs on the underside of broad leaved trees and thus does not face this risk and thus can lay larger egg clusters. No differences in cannibalism rates were found between the two species. These findings have implications for the use of ladybirds as biological control agents in spruce forests.
The South Sudan Defence Force: patriots, collaborators or spoilers?
Authors: Arnold Matthew B. 
Published: November 2007

ABSTRACTDespite stipulations in the Sudan's 2005 Comprehensive Peace Agreement (CPA) that all ‘other armed groups’ be demobilised by January 2006, the South Sudan Defence Force (SSDF) continued to maintain a significant armed presence in South Sudan. This paper analyses the dynamics of the organisation, the impact of its ongoing presence on the security situation and reconstruction efforts, and attempts by the government of South Sudan to counteract the SSDF from January to August 2006. It argues that the strategies implemented by the government to counter the SSDF were fairly successful in that there was no major return to conflict. However, it concludes that the SSDF's continued presence, while hindered, has the potential to spark a return to civil war.
White-collar fundamentalism: interrogating youth religiosity on Nigerian university campuses
Authors: Obadare Ebenezer 
Published: November 2007

ABSTRACTHome historically to a politically engaged youth sector, Nigeria has, over the past two decades, witnessed a growing incidence of religious extremism involving educated youth, especially within university campuses. For all its important ramifications, and despite the continued infusion of social and political activity in the country by religious impulse, this phenomenon has yet to receive a systematic or coherent treatment in the relevant literature. This paper aims to locate youthful angst displayed by Nigerian university students within the context of postcolonial anomie and the attendant immiseration of civil society. Youth religious extremism on Nigerian campuses reflects both young people's frustration with national processes, and their perceived alienation from modernity's ‘cosmopolitan conversation’.
When men do women's work: structural adjustment, unemployment and changing gender relations in the informal economy of Accra, Ghana
Authors: Overå Ragnhild 
Published: November 2007

ABSTRACTEconomic crisis and structural adjustment in Ghana have put large numbers of formal sector employees and civil servants out of work. This informalisation process has gendered consequences. Unemployed people, rural–urban migrants and school-leavers of both genders seek employment in the urban informal economy, and increasingly take up ‘female’ occupations – particularly in retail trade. Overcrowding in women's economic domains thus occurs. This study examines the livelihood strategies of informally employed men and women in Accra. It is argued that gender ideologies regarding appropriate occupations for women and men are continuously adapted in response to a changing political economy. Thus, even if female traders face competition, declining returnsanda heavier dependency burden, frustration with government policies failing to create decent jobs (for men) is more prevalent than gender antagonism and ridicule of those who find gender-atypical ways of eking out a living.
Business success, Angola-style: postcolonial politics and the rise and rise of Sonangol
Authors: de Oliveira Ricardo Soares 
Published: November 2007

ABSTRACTThis paper investigates a paradoxical case of business success in one of the world's worst-governed states, Angola. Founded in 1976 as the essential tool of the Angolan end of the oil business, Sonangol, the national oil company, was from the very start protected from the dominant (both predatory and centrally planned) logic of Angola's political economy. Throughout its first years, the pragmatic senior management of Sonangol accumulated technical and managerial experience, often in partnership with Western oil and consulting firms. By the time the ruling party dropped Marxism in the early 1990s, Sonangol was the key domestic actor in the economy, an island of competence thriving in tandem with the implosion of most other Angolan state institutions. However, the growing sophistication of Sonangol (now employing thousands of people, active in four continents, and controlling a vast parallel budget of offshore accounts and myriad assets) has not led to the benign developmental outcomes one would expect from the successful ‘capacity building’ of the last thirty years. Instead, Sonangol has primarily been at the service of the presidency and its rentier ambitions. Amongst other themes, the paper seeks to highlight the extent to which a nominal ‘failed state’ can be successful amidst widespread human destitution, provided that basic tools for elite empowerment (in this case, Sonangol and the means of coercion) exist to ensure the viability of incumbents.
How does neopatrimonialism affect the African state's revenues? The case of tax collection in Zambia
Authors: Soest Christian von 
Published: November 2007

ABSTRACTFollowing the neopatrimonialism paradigm, it can be hypothesised that in African states informal politics of the rulers infringe on the collection of taxes and in turn reduce state revenue. This article tests this proposition for the case of Zambia. Neopatrimonial continuity in the country is evidenced by three factors: the concentration of political power, the award of personal favours, and the misuse of state resources. Despite this continuity, the revenue performance increased considerably with the creation of the semi-autonomous Zambia Revenue Authority. Donor pressure has been the most important intervening variable accounting for this improvement. Yet, strengthening the collection of central state revenue has been consistent with a neopatrimonial rationale, and may even have fed neopatrimonialism overall, by providing increased resources for particularistic expenditure.
Impacts of Chinese imports and coping strategies of local producers: the case of small-scale footwear enterprises in Ethiopia
Authors: Gebre-Egziabher Tegegne 
Published: November 2007

ABSTRACTThe footwear sector in Ethiopia is dominated by cheap imports from Asia, particularly from China. This has inflicted heavy impacts on the sector, and threatened its competitiveness in the domestic market. This study examines the impact of imports and coping strategies of firms to withstand the competition. Firm level data were gathered from micro, small and medium footwear enterprises. The findings revealed that Chinese shoes are superior in design, price and quality, with the result that they have taken over the domestic market. The impact of Chinese imports on local producers varied from downsizing, bankruptcy, loss of assets and property, to downgrading activities and informalising operations. Firms have pursued coping strategies that focused on improving design and quality, as well as lowering prices and profit margins. Coping strategies appear to be differentiated by size of firms, and have some association with the performance of firms. The ways forward for local producers should focus on collaborative engagements of stakeholders and government to overcome the competitive disadvantages of firms. Training, technology, quality control, benchmarking and reorganization of production should be designed as a package of intervention. In addition, strengthening local producers to engage in collective actions and promoting exports should also be given proper attention.
The accretion disk paradigm for young stars
Authors: Bertout Claude 
Published: November 2007

AbstractAccretion and magnetic fields play major roles in several of the many models put forward to explain the properties of T Tauri stars since their discovery by Alfred Joy in the 1940s. Early investigators already recognized in the 1950s that a source of energy external to the star was needed to account for the emission properties of these stars in the optical range.The opening of new spectral windows from the infrared to the ultraviolet in the 1970s and 1980s showed that the excess emission of T Tauri stars and related objects extends into all wavelength domains, while evidence of outflow and/or infall in their circumstellar medium was accumulating.Although the disk hypothesis had been put forward by Merle Walker as early as 1972 to explain properties of YY Orionis stars and although Lynden-Bell and Pringle worked out the accretion disk model and applied it specifically to T Tauri stars in 1974, the prevailing model for young stellar objects until the mid-1980s assumed that they experienced extreme solar-type activity. It then took until the late 1980s before the indirect evidence of disks presented by several teams of researchers became so compelling that a paradigm shift occurred, leading to the current consensual picture.I briefly review the various models proposed for explaining the properties of young stellar objects, from their discovery to the direct observations of circumstellar disks that have so elegantly confirmed the nature of young stars. I will go on to discuss more modern issues concerning their accretion disk properties and conclude with some results obtained in a recent attempt to better understand the evolution of Taurus-Auriga young stellar objects.
Measurements of magnetic fields on T Tauri stars
Authors: Johns–Krull Christopher M. 
Published: November 2007

AbstractStellar magnetic fields including a strong dipole component are believed to play a critical role in the early evolution of newly formed stars and their circumstellar accretion disks. It is currently believed that the stellar magnetic field truncates the accretion disk several stellar radii above the star. This action forces accreting material to flow along the field lines and accrete onto the star preferentially at high stellar latitudes. It is also thought that the stellar rotation rate becomes locked to the Keplerian velocity near the radius where the disk is truncated. This paper reviews recent efforts to measure the magnetic field properties of low mass pre-main sequence stars, focussing on how the observations compare with the theoretical expectations. A picture is emerging indicating that quite strong fields do indeed cover the majority of the surface on these stars; however, the dipole component of the field appears to be alarmingly small. On the other hand, at least one accretion model which takes into account the non-dipole nature of the magnetic field provides predictions relating various stellar and accretion parameters which are present in the current data.
Magnetic field at the inner disk edge
Authors: Jardine Moira , Gregory Scott G. , Donati Jean-François 
Published: November 2007

AbstractOur present understanding of the coronal structure of T Tauri stars is fragmentary and observations in different wavelength regimes often appear to give contradictory results. X-ray data suggest the presence of magnetic loops on a variety of scales, from compact loops of size less than a stellar radius, up to very large loops of up to 10 stellar radii which may connect to the disk. While some stars show a clear rotational modulation in X-rays, implying distinct bright and dark regions, many do not. This picture is complicated by the accretion process itself, which also contributes to the X-ray emission. The location of the inner edge of the accretion disk and the nature of the magnetic field there are still hotly-contested issues. Accretion indicators often suggest the presence of discrete accretion funnels. This has implications for the structure of the corona, as does the presence of an outflowing wind. All of these factors are linked to the structure of the magnetic field, which we are now beginning to unravel through Zeeman-Doppler imaging. In this review I will describe the present state of our understanding of the magnetic structure of T Tauri coronae and the impact this has during such an early evolutionary stage.
Submillimetre polarimetric observations of magnetic fields in star-forming regions
Authors: Curran Rachel L. , Chrysostomou Antonio , Matthews Brenda C. 
Published: November 2007

AbstractSubmillimetre imaging polarimetry is one of the most powerful tools at present for studying magnetic fields in star-forming regions, and the only way to gain significant information on the structure of these fields. We present analysis of the largest sample (to date) of both high- and low-mass star-forming regions observed using this technique. A variety of magnetic field morphologies are observed, with no single field morphology favoured. Both the continuum emission morphologies and the field morphologies are generally more complex for the high-mass sample than the low-mass sample. The large scale magnetic field (observed with the JCMT; 14″ resolution) of NGC1333 IRAS2 is interpreted to be weak (compared to the energetic contributions due to turbulence) from the random field pattern observed. On smaller scales (observed with the BIMA array; 3″ resolution) the field is observed to be almost radial, consistent with the polarisation nulls in the JCMT data – suggesting that on smaller scales, the field may be more important to the star formation process. An analysis of the magnetic field direction and the jet/outflow axis is also discussed. Cumulative distribution functions of the difference between the mean position angle of the magnetic field vectors and the jet/outflow axis reveal no correlation. However, visual inspection of the maps reveal alignment of the magnetic field and jet/outflow axis in 7 out of 15 high-mass regions and 3 out of 8 low-mass regions.
Time variable funnel flows
Authors: Alencar Silvia H. P. 
Published: November 2007

AbstractMagnetospheric accretion models are the current consensus to explain the main observed characteristics of classical T Tauri stars. In recent years the concept of a static magnetosphere has been challenged by synoptic studies of classical T Tauri stars that show strong evidence for the accretion process to be dynamic on several timescales and governed by changes in the magnetic field configuration. At the same time numerical simulation results predict evolving funnel flows due to the interaction between the stellar magnetosphere and the inner disk region. In this contribution we will focus on the main recent observational evidences for time variable funnel flows and compare them with model predictions.
Radiative-transfer modelling of funnel flows
Authors: Harries Tim J. 
Published: November 2007

AbstractEmission line profiles from pre-main-sequence objects accreting via magnetically-controlled funnel flows encode information on the geometry and kinematics of the material on stellar radius scales. In order to extract this information it is necessary to perform radiative-transfer modelling of the gas to produce synthetic line profiles. In this review I discuss the physics that needs to be included in such models, and the numerical methods and assumptions that are used to render the problem tractable. I review the progress made in the field over the last decade, and summarize the main successes and failures of the modelling work.
Measuring the physical conditions of accreting gas in T Tauri systems
Authors: Bary Jeffrey S. , Matt Sean P. 
Published: November 2007

AbstractHydrogen emission lines observed from T Tauri stars (TTS) are associated with the accretion/outflow of gas in these young star forming systems. Magnetospheric accretion models have been moderately successful at reproducing the shapes of several Hi emission line profiles, suggesting that the emission arises in the accretion funnels. Despite considerable effort to model and observe these emission features, the physical conditions of the gas confined to the funnel flows remain poorly constrained by observation. We conducted a mutli-epoch near-infrared spectroscopic survey of 16 actively accreting classical TTS in the Taurus-Auriga star forming region. We present an analysis of these simultaneously acquired line flux ratios of many Paschen and Brackett series emission lines, in which we compare the observed ratios to those predicted by the Case B approximation of hydrogen recombination line theory. We find that the line flux ratios for the Paschen and Brackett decrements as well as a comparison between Brγ and Paschen transitions agree well with the Case B models with T < 5000 K and ne ≈ 1010 cm−3.