5,178 research outputs found

    Relative Price Adjustment and the UK Philips Curve

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    We find that measures of the distribution of relative price changes are significant when included in a standard model of the UK Phillips curve based on time dependent price adjustment. Since the inclusion of these variables is not implied by this model but is implied by a state-dependent model of price adjustment or by a time-dependent model with allowance for heterogeneity among price-setters, we conclude that the familiar time-dependent model does not provide a complete account of the Phillips curve.New Keynesian Phillips curve, Relative Price Changes, Labour share

    Explaining Small-Business Development: A Small-Business Development Model Combining the Maslow and the Hayes and Wheelwright Models

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    This paper looks at small-business management from the standpoint of Maslow’s hierarchy of needs and Hayes and Wheelwright’s four-stage model. The paper adapts Maslow’s hierarchy of needs model to small- business development and evolution. Additionally, Hayes and Wheelwright’s four-stage model is combined with the adapted Maslow small-business development model. The implications of the new model on the development of small businesses and future research are discussed

    Weak Gravitational Lensing and Cluster Mass Estimates

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    Hierarchical theories of structure formation predict that clusters of galaxies should be embedded in a web like structure, with filaments emanating from them to large distances. The amount of mass contained within such filaments near a cluster can be comparable to the collapsed mass of the cluster itself. Diffuse infalling material also contains a large amount of mass. Both these components can contribute to the cluster weak lensing signal. This ``projection bias'' is maximized if a filament lies close to the line-of-sight to a cluster. Using large--scale numerical simulations of structure formation in a cosmological constant dominated cold dark matter model, we show that the projected mass typically exceeds the actual mass by several tens of percent. This effect is significant for attempts to estimate cluster masses through weak lensing observations, and will affect weak lensing surveys aimed at constructing the cluster mass function.Comment: 4 pages, 3 figures. LaTeX2e, uses emulateapj.sty and onecolfloat.sty. To be submitted to the Astrophysical Journal Letter

    Landscape Sustainability in a Sonoran Desert City

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    The objective of this paper is to discuss concepts of landscape sustainability in the Phoenix metropolitan area. Phoenix is situated in the greater Salt River Valley of the lower Sonoran Desert in the southwest United States. In this paper I use the ecological frameworks of ecosystem services and resiliency as a metric for understanding landscape sustainability. An assessment of landscape sustainability performance benchmarks were made by surveying research findings of scientists affiliated with the Central Arizona Phoenix Long Term Ecological Research Project (CAP LTER). In Phoenix, present day emphases on cultural, aesthetic, and habitat formation ecosystem services within an arid ecoregion of low natural resilience coupled to a complex matrix of socioeconomic stratification, excessive landscape water use and pruning practices has had the undesired effect of degrading landscape sustainability. This has been measured as mixed patterns of plant diversity and human-altered patterns of carbon regulation, microclimate control, and trophic dynamics. In the future, sustainable residential landscaping in desert cities such as Phoenix may be fostered through use of water-conserving irrigation technologies, oasis-style landscape designs motifs, recycling of landscape green waste, and conservative plant pruning strategies

    Stratosphere-troposphere separation of nitrogen dioxide columns from the TEMPO geostationary satellite instrument

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    Separating the stratospheric and tropospheric contributions in satellite retrievals of atmospheric NO2 column abundance is a crucial step in the interpretation and application of the satellite observations. A variety of stratosphere–troposphere separation algorithms have been developed for sun-synchronous instruments in low Earth orbit (LEO) that benefit from global coverage, including broad clean regions with negligible tropospheric NO2 compared to stratospheric NO2. These global sun-synchronous algorithms need to be evaluated and refined for forthcoming geostationary instruments focused on continental regions, which lack this global context and require hourly estimates of the stratospheric column. Here we develop and assess a spatial filtering algorithm for the upcoming TEMPO geostationary instrument that will target North America. Developments include using independent satellite observations to identify likely locations of tropospheric enhancements, using independent LEO observations for spatial context, consideration of diurnally varying partial fields of regard, and a filter based on stratospheric to tropospheric air mass factor ratios. We test the algorithm with LEO observations from the OMI instrument with an afternoon overpass, and from the GOME-2 instrument with a morning overpass. We compare our TEMPO field of regard algorithm against an identical global algorithm to investigate the penalty resulting from the limited spatial coverage in geostationary orbit, and find excellent agreement in the estimated mean daily tropospheric NO2 column densities (R2=0.999, slope=1.009 for July and R2=0.998, slope=0.999 for January). The algorithm performs well even when only small parts of the continent are observed by TEMPO. The algorithm is challenged the most by east coast morning retrievals in the wintertime (e.g., R2=0.995, slope=1.038 at 14:00 UTC). We find independent global LEO observations (corrected for time of day) provide important context near the field-of-regard edges. We also test the performance of the TEMPO algorithm without these supporting global observations. Most of the continent is unaffected (R2=0.924 and slope=0.973 for July and R2=0.996 and slope=1.008 for January), with 90 % of the pixels having differences of less than ±0.2×1015 molecules cm−2 between the TEMPO tropospheric NO2 column density and the global algorithm. For near-real-time retrieval, even a climatological estimate of the stratospheric NO2 surrounding the field of regard would improve this agreement. In general, the additional penalty of a limited field of regard from TEMPO introduces no more error than normally expected in most global stratosphere–troposphere separation algorithms. Overall, we conclude that hourly near-real-time stratosphere–troposphere separation for the retrieval of NO2 tropospheric column densities by the TEMPO geostationary instrument is both feasible and robust, regardless of the diurnally varying limited field of regard.The authors are grateful to Kelly Chance, Xiong Liu, John Houck, Peter Zoogman, and other members of the TEMPO trace gas retrieval team for their input in preparation of this paper. Work at Dalhousie University was supported by Environment and Climate Change Canada. The authors also gratefully acknowledge the free use of TEMIS NO2 data from the GOME-2 sensor provided by http://www.temis.nl, last access: 12 November 2018, and the NASA Standard Product NO2 data from OMI provided by https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary, last access: 9 November 2018. (Environment and Climate Change Canada)https://www.atmos-meas-tech.net/11/6271/2018/Published versio

    Optimizing baryon acoustic oscillation surveys – I. Testing the concordance ΛCDM cosmology

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    We optimize the design of future spectroscopic redshift surveys for constraining the dark energy via precision measurements of the baryon acoustic oscillations (BAO), with particular emphasis on the design of the Wide-Field Multi-Object Spectrograph (WFMOS). We develop a model that predicts the number density of possible target galaxies as a function of exposure time and redshift. We use this number counts model together with fitting formulae for the accuracy of the BAO measurements to determine the effectiveness of different surveys and instrument designs. We search through the available survey parameter space to find the optimal survey with respect to the dark energy equation-of-state parameters according to the Dark Energy Task Force Figure-of-Merit, including predictions of future measurements from the Planck satellite. We optimize the survey to test the LambdaCDM model, assuming that galaxies are pre-selected using photometric redshifts to have a constant number density with redshift, and using a non-linear cut-off for the matter power spectrum that evolves with redshift. We find that line-emission galaxies are strongly preferred as targets over continuum emission galaxies. The optimal survey covers a redshift range 0.8 < z < 1.4, over the widest possible area (6000 sq. degs from 1500 hours observing time). The most efficient number of fibres for the spectrograph is 2,000, and the survey performance continues to improve with the addition of extra fibres until a plateau is reached at 10,000 fibres. The optimal point in the survey parameter space is not highly peaked and is not significantly affected by including constraints from upcoming supernovae surveys and other BAO experiments.Comment: 15 pages, 9 figure

    The importance of scale in spatially varying coefficient modeling

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    While spatially varying coefficient (SVC) models have attracted considerable attention in applied science, they have been criticized as being unstable. The objective of this study is to show that capturing the "spatial scale" of each data relationship is crucially important to make SVC modeling more stable, and in doing so, adds flexibility. Here, the analytical properties of six SVC models are summarized in terms of their characterization of scale. Models are examined through a series of Monte Carlo simulation experiments to assess the extent to which spatial scale influences model stability and the accuracy of their SVC estimates. The following models are studied: (i) geographically weighted regression (GWR) with a fixed distance or (ii) an adaptive distance bandwidth (GWRa), (iii) flexible bandwidth GWR (FB-GWR) with fixed distance or (iv) adaptive distance bandwidths (FB-GWRa), (v) eigenvector spatial filtering (ESF), and (vi) random effects ESF (RE-ESF). Results reveal that the SVC models designed to capture scale dependencies in local relationships (FB-GWR, FB-GWRa and RE-ESF) most accurately estimate the simulated SVCs, where RE-ESF is the most computationally efficient. Conversely GWR and ESF, where SVC estimates are naively assumed to operate at the same spatial scale for each relationship, perform poorly. Results also confirm that the adaptive bandwidth GWR models (GWRa and FB-GWRa) are superior to their fixed bandwidth counterparts (GWR and FB-GWR)

    The Attitudes about Complex Therapy Scale (ACTS) in Type 2 Diabetes and Cardiovascular Disease: Development, Validity and Reliability

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    Background: Type 2 diabetes is associated with cardiovascular disease, and patients with both conditions are prescribed complex medication regimens. Aim: The aim was to develop a reliable and valid measure of attitudes associated with the prescription and management of multiple medicines in patients with Type 2 diabetes and cardiovascular disease. Methods: Principal component analysis (PCA) and Cronbach alpha assessed the reliability of the Attitudes about Complex Therapy Scale (ACTS). Examinations of relationships with related measures inform concurrent validity. Questionnaires were sent to a cross-sectional sample of 480 people prescribed multiple medicines for co-morbid Type 2 diabetes. Results: Cronbach alpha was 0.76, indicating the scale had good internal reliability. PCA rotated a four factor model accounting for 37% of the variance. Four subscales identified; 1. Concerns about multiple medicines and increasing numbers of medicines; 2.Anxiety over missed medicines; 3. Desires to substitute medicines and reduce the number of medicines prescribed and; 4. Perceptions related to organising and managing complex therapy. The ACTS showed significant relationships with measures of anxiety, depression, general beliefs about medicines and self-efficacy. Also, the ACTS significantly correlated with adherence to medicines, showing good predictive validity. Conclusion: The ACTS was designed to assess negative attitudes towards complex therapy and multiple medication management. This tool could aid prescribing decisions and may identify people who are intentionally non-adherent to all or some of their medicines

    Application of computational fluid dynamics modelling to an ozone contactor

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    Computational fluid dynamics (CFD) modelling has been applied to examine the operation of the pre-ozonation system at Wiggins Waterworks, operated by Umgeni Water in Durban, South Africa. A hydraulic model has been satisfactorily verified by experimental tracer tests. The turbulence effect induced by the gas injection was modelled by increasing the level of turbulence intensity at the ozone contactor inlet. The simulated tracer response corresponded closely to the experimental results. The framework of ozone reaction modelling was subsequently investigated using values of rate constants from the literature. The predicted profile of residual ozone concentration suggests the current operating strategy can be improved to optimise the ozone utilisation. The wide range of values found in the literature suggests that the ozone reactions are strongly dependent on site-specific characteristics of the water. Further experimental work is required to determine rate constants which are applicable to water from the Inanda Dam. Water SA Vol.30(1): 51-5

    Effects of participant and target system lability upon PK performance using an I Ching task

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    Relatively few parapsychological experiments investigating micro-PK effects have been designed to consider psychological or individual differences factors, and those variables that have been considered have been subject to too few replications to give a clear indication of which persons may perform best under which conditions. Previous research by the first author discovered and replicated an interaction effect between an individual differences factor, participant lability, and a situational factor, target system lability. The present study was designed to conceptually replicate that finding using a novel task so as to control for possible artifacts. An alternative task was built around the I Ching divination procedure, which it was felt retained important characteristics of being personally relevant for the participant and intuitively straightforward to understand. An opportunity sample of 34 participants completed a measure of lability and decided upon a personal question that the I Ching could help with. Participants were run individually and completed a Q-sort of all 64 hexagram descriptions based on their applicability to their question. Once completed they cast three hexagrams using a computer based program that used a live random number generator (Live), the pseudorandom function of the computer (Pseudo) and a predetermined list of random numbers derived from published tables (Table). The Q-sort positions were used to rate the applicability of the selected hexagrams. Although the general pattern of performance was in line with prediction, with the highest average ratings awarded to hexagrams selected by the most labile Live method, next highest for the moderately labile Pseudo method and worst ratings for the most stabile Table method, the mean shifts were small and nonsignificant. Similarly, although the highest overall performance was achieved by the most labile participant group, an intermediate level of performance was recorded by the intermediate group and worst performance was by the stabile group, the modest differences were not significant. Therefore, despite the pattern of performance being superficially similar to that reported in previous studies, this experiment was not able to replicate the interaction between participant and target system lability. Possible causes for this failure to replicate are considered
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