2,073 research outputs found

    Differential Hawthorne Effect by Cueing, Sex, and Relevance

    Get PDF
    This study attempted to create experimentally the Hawthorne effect in a freshman general psychology class at Utah State University during tall quarter of 1967. It also attempted to discover the differential effect of cueing, sex, and relevance on the experimental creation of the Hawthorne effect as measured by six general psychology criterion tests. The design of this study included a control group and three experimental groups. The following five hypotheses were postulated: The experimental groups will show greater influence from the Hawthorne effect than the control group. Within the three experimental groups there will be an increasing Hawthorne effect with the least effect in the subject-object cue group and the greatest effect in the subject-object-observer group as compared to the control group. The females in all experimental groups will show significantly greater Hawthorne effect than males within the same groups. The group rating high on the Relevance scale will show significantly greater Hawthorne effect than the groups rating low in relevance. There will be sufficient interactive effects between factors to the extent that some will reach significance. The hypotheses were tested by means of analysis of covariance with ACT predicted grade point average as the covariate. None of the differences were significant at the .05 level. It was concluded that the Hawthorne effect does not exist as a potent enough variable to distort the influence of the independent variable on the dependent variable in educational and psychological investigations of short duration involving freshman university students. It was also concluded that the variables of Cueing, Sex, and Relevance are not functionally related to the creation of the Hawthorne effect and, therefore, need not be controlled

    The impact of sarcoptic mange Sarcoptes scabiei on the British fox Vulpes vulpes population

    Get PDF
    1. Disease epizootics can significantly influence host population dynamics and the structure and functioning of ecological communities. Sarcoptic mange Sarcoptes scabiei has dramatically reduced red fox populations Vulpes vulpes in several countries, including Britain, although impacts on demographic processes are poorly understood. We review the literature on the impact of mange on red fox populations, assess its current distribution in Britain through a questionnaire survey and present new data on resultant demographic changes in foxes in Bristol, UK. 2. A mange epizootic in Sweden spread across the entire country in < 10 years resulting in a decline in fox density of up to 95%; density remained lowered for 15–20 years. In Spain, mange has been enzootic for > 75 years and is widely distributed; mange presence was negatively correlated with habitat quality. 3. Localized outbreaks have occurred sporadically in Britain during the last 100 years. The most recent large-scale outbreak arose in the 1990s, although mange has been present in south London and surrounding environs since the 1940s. The questionnaire survey indicated that mange was broadly distributed across Britain, but areas of perceived high prevalence (> 50% affected) were mainly in central and southern England. Habitat type did not significantly affect the presence/absence of mange or perceived prevalence rates. Subjective assessments suggested that populations take 15–20 years to recover. 4. Mange appeared in Bristol’s foxes in 1994. During the epizootic phase (1994–95), mange spread through the city at a rate of 0.6–0.9 km/month, with a rise in infection in domestic dogs Canis familiaris c. 1–2 months later. Juvenile and adult fox mortality increased and the proportion of females that reproduced declined but litter size was unaffected. Population density declined by > 95%. 5. In the enzootic phase (1996–present), mange was the most significant mortality factor. Juvenile mortality was significantly higher than in the pre-mange period, and the number of juveniles classified as dispersers declined. Mange infection reduced the reproductive potential of males and females: females with advanced mange did not breed; severely infected males failed to undergo spermatogenesis. In 2004, Bristol fox population density was only 15% of that in 1994

    Fisheries and Aquaculture and Their Potential Roles in Development: An Assessment of the Current Evidence

    Get PDF
    Commissioned by the International Sustainability Unity, this report investigates a number of innovative solutions that have been developed to deal with five key challenges that are impeding progress in achieving sustainable fisheries: overcapacity; perverse subsidies; poor governance; lack of data; and by-catch and discards. These key challenges are interlinked and affect the sustainability of fisheries both directly as well as indirectly by undermining instances of good management. Through 22 case studies demonstrating good practice, we explore how these challenges have been addressed around the world and how these approaches might be scaled up and applied in other fisheries. Each case study draws on published material and interviews with key people involved in the fishery. The main report draws lessons from these case studies

    The Control of Armyworms and Cutworms

    Get PDF
    The armyworm and several species of cutworms are always present in the gardens and fields of Iowa. Cutworms cause great annoyance here and there in the spring by cutting off transplanted and other young plants in vegetable and flower gardens. Young corn plants also are particularly susceptible to their attack. The armyworm Is most frequently found In low-lying grassland and generally feeds singly, as do cutworms. The Injury by armyworms and cutworms In fields or pastures of timothy, bluegrass and of certain cereal crops, Is not so noticeable and is usually entirely overlooked by the grower

    Evaluating the effects of cohesive processes on sediment distribution in an idealized, partially-mixed estuary using a numerical model

    Get PDF
    An idealized two-dimensional model is designed to represent a longitudinal section of a partially-mixed estuary, accounting for a freshwater source, tides, and estuarine circulation, but neglecting across-channel variations. The Community Sediment Transport Modeling System (CSTMS) is used to simulate suspended transport, erosion, and deposition within the Regional Ocean Modeling System (ROMS). This version of the model also includes cohesive processes such as consolidation and swelling of the sediment bed; sediment-induced stratification; and variable settling velocities. To better understand the processes controlling fine-grained sediment transport in the York River, VA, the primary features of the idealized estuary mimic that system, and the model uses site-specific field measurements of erodibility and settling properties to constrain sediment transport model parameters. Simulations that include different combinations of cohesive processes are used to determine the impact of bed consolidation and swelling, and sediment-induced stratification on the depositional patterns of various sediment types along the idealized estuary and over a tidal cycle. The sediment classes represent the range of particle settling velocities (ws) seen from in situ observations; and include resilient muddy fecal pellets (ws = 2.4 mm s-1 ), very fine sand (ws = 6 mm s-1 ), lowerdensity flocs (ws = 0.8 mm s-1 ), and unflocculated primary particles (ws = 0.1 mm s-1 ). Slower settling particles preferentially remain in suspension, leading to a more even spatial distribution. Faster settling sediment is more readily trapped in the estuarine region of convergence or estuarine turbidity maximum (ETM). Considering sedimentinduced stratification traps sediment in the lower water column, and bed consolidation limits suspension of lower ws sediment, then the incorporation of these processes are likely to enhance the trapping of relatively higher ws sediment in the ETM region

    Cep70 and Cep131 contribute to ciliogenesis in zebrafish embryos.

    Get PDF
    BACKGROUND: The centrosome is the cell's microtubule organising centre, an organelle with important roles in cell division, migration and polarity. However, cells can divide and flies can, for a large part of development, develop without them. Many centrosome proteins have been identified but the roles of most are still poorly understood. The centrioles of the centrosome are similar to the basal bodies of cilia, hair-like extensions of many cells that have important roles in cell signalling and development. In a number of human diseases, such Bardet-Biedl syndrome, centrosome/cilium proteins are mutated, leading to polycystic kidney disease, situs inversus, and neurological problems, amongst other symptoms. RESULTS: We describe zebrafish (Danio rerio) embryos depleted for two uncharacterised, centrosome proteins, Cep70 and Cep131. The phenotype of these embryos resembles that of zebrafish mutants for intraflagellar transport proteins (IFTs), with kidney and ear development affected and left-right asymmetry randomised. These organs and processes are those affected in Bardet-Biedl syndrome and other similar diseases. Like these diseases, the root cause of the phenotype lies, in fact, in dysfunctional cilia, which are shortened but not eliminated in several tissues in the morphants. Centrosomes and basal bodies, on the other hand, are present. Both Cep70 and Cep131 possess a putative HDAC (histone deacetylase) interacting domain. However, we could not detect in yeast two-hybrid assays any interaction with the deacetylase that controls cilium length, HDAC6, or any of the IFTs that we tested. CONCLUSION: Cep70 and Cep131 contribute to ciliogenesis in many tissues in the zebrafish embryo: cilia are made in cep70 and cep131 morphant zebrafish embryos but are shortened. We propose that the role of these centrosomal/basal body proteins is in making the cilium and that they are involved in determination of the length of the axoneme.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

    The Vertical Wind Tunnel of the National Advisory Committee for Aeronautics

    Get PDF
    The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics is described in this report. The tunnel was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the spin of an airplane. Satisfactory air flow has been attained with a velocity that is uniform over the jet to within plus or minus 0.5 per cent. The turbulence present in the tunnel has been compared with that of several other tunnels by means of the results of sphere drag tests and was found to average well with the values of those tunnels. Included also in the report are comparisons of results of stable autorotation and of rolling-moment test obtained both in the vertical tunnel and in the old horizontal 5-foot atmospheric tunnel. (author

    Preliminary wind-tunnel investigation of an NACA 23012 airfoil with various arrangements of venetian-blind flaps

    Get PDF
    Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a large-chord NACA 23012 airfoil with several arrangements of venetian-blind flaps to determine the aerodynamic section characteristics as affected by the over-all flap chord, the chords of the slats used to form the flap, the slat spacing, the number of slats and the position of the flap with respect to the wing. Complete section data are given in the form of graphs for all the combinations tested
    corecore