925 research outputs found
The Christian voice in philosophy
In this paper the Rev. Stuart Fowler outlines a Christian voice in Philosophy and urges the Christian philosopher to investigate his position and his stance with integrity and honesty
Chaos and order in education
The relation between chaos and order in social systems has been a recurring theme in educational literature over the last decade. Discussions commonly propose links with developments in mathematics and physics. The authors take a critically constructive look at some of the fundamental questions that underlie the discussion. They look at the nature of the relevant developments in mathematics and physics in their possible relation to educational theory and practice. They proceed to explore the role of order, predictability and control and the place of religion in the education systems, and in academic discourse, of today's pluralist societies.
South African Journal of Education Vol.24(1) 2004: 64-6
M12L8 metallo-supramolecular cube with cyclotriguaiacylene-type ligand: spontaneous resolution of cube and its constituent host ligand.
Data to support study of Ag12L8 metallo-cube and clathrate complexes of tris-(4-methylthiazolyl)cyclotriguaiacylene, where both Ag12L8 cube and clathrate complexes show spontaneous chiral resolution on crystallisation
Investigation of Systematic Bias in Radiometric Diameter Determination of Near-Earth Asteroids: the Night Emission Simulated Thermal Model (NESTM)
The Near-Earth Asteroid Thermal Model (NEATM, Harris, 1998) has proven to be
a reliable simple thermal model for radiometric diameter determination. However
NEATM assumes zero thermal emission on the night side of an asteroid. We
investigate how this assumption affects the best-fit beaming parameter,
overestimates the effective diameter and underestimates the albedo at large
phase angles, by testing NEATM on thermal IR fluxes generated from simulated
asteroid surfaces with different thermal inertia. We compare NEATM to radar
diameters and find that NEATM overestimates the diameter when the beaming
parameter is fitted to multi-wavelength observations and underestimates the
diameter when the default beaming parameter is used. The Night Emission
Simulated Thermal Model (NESTM) is introduced. NESTM models the night side
temperature as an iso-latitudinal fraction (f) of the maximum day side
temperature (Maximum temperature calculated for NEATM with beaming parameter =
1). A range of f is found for different thermal parameters, which depend on the
thermal inertia. NESTM diameters are compared with NEATM and radar diameters,
and it is shown that NESTM may reduce the systematic bias in overestimating
diameters. It is suggested that a version of the NESTM which assumes the
thermal inertia = 200 S.I. units is adopted as a default model when the solar
phase angle is greater than 45 degrees.Comment: 48 pages, 10 Figures, 5 Table
Recommended from our members
Accounting for model error in strong-constraint 4DVar data assimilation
The strong constraint formulation of four-dimensional variational data assimilation (4DVar) assumes that the model used in the process perfectly describes the true dynamics of the system. However, this assumption often does not hold and the use of an erroneous model in strong constraint 4DVar can lead to a sub-optimal estimation of the initial conditions. We show how the presence of model error can be correctly accounted for in strong constraint 4D-Var by allowing for errors in both the observations and the model when considering the statistics of the innovation vector. We demonstrate that when these combined model error and observation error statistics are used in place of the standard observation error statistics in the strong constraint formulation of 4DVar, a statistically more accurate estimate of the initial state is obtained.
The calculation of the combined model error and observation error statistics requires the specification of model error covariances, which in practice are often unknown. We present a method to estimate the combined statistics from innovation data that does not require explicit specification of the model error covariances. Numerical experiments using the linear advection equation and a simple nonlinear coupled model demonstrate the success of the new methods in reducing the error in the estimate of the initial state, even in the case when only the uncorrelated part of the model error is accounted for
Multiple trait dimensions mediate stress gradient effects on plant biomass allocation, with implications for coastal ecosystem services
The plant economic spectrum (PES) predicts a suite of correlated traits in a continuum from resource conservation to rapid resource acquisition. In addition to competing for resources, plants need to cope with other environmental stresses to persist and reproduce. Yet, it is unclear how multiple strategies (i.e. traits uncorrelated with the PES) affect plant biomass allocation, hindering our ability to connect environmental gradients to ecosystem services.We examined intraspecific dimensionality of leaf and root traits in the salt marsh pioneer species Spartina anglica across salinity, redox and sand content gradients, and related them to above-ground and below-ground plant biomass—properties associated with wave attenuation and sediment stabilization in coastal marshes.Through principal component analysis, we did not find support for a single PES trait dimension (strategy), but instead identified four trait dimensions: (a) leaf economic spectrum (LES, leaf analogue of PES); (b) fine roots-rhizomes; (c) coarse roots; and (d) salt extrusion. Structural equation modelling showed a shift towards the conservative side of the LES under increasing salinity, while redox had a positive influence on the coarse roots dimension. In turn, these trait dimensions were strongly associated with above-ground and below-ground biomass (BLW biomass) allocation.These results indicate that under high salinity, plants will adopt a conservative strategy and will invest more in BLW biomass. Yet, high sediment redox would still allow plants to invest in above-ground biomass. Therefore, plants' trait-mediated biomass allocation depends on the specific combination of abiotic factors experienced at the local scale.Synthesis. Our study highlights the importance of considering multiple ecological strategies for understanding the effect of the environment on plants. Abiotic stresses can influence multiple trait strategy-dimensions, with consequences for ecosystem functioning
Knowledge and Awareness of Congenital Cytomegalovirus Among Women
Background. Congenital cytomegalovirus (CMV) infection is a leading cause of disabilities in children, yet the general public appears to have little awareness of CMV. Methods. Women were surveyed about newborn infections at 7 different geographic locations. Results. Of the 643 women surveyed, 142 (22%) had heard of congenital CMV. Awareness increased with increasing levels of education (P < .0001). Women who had worked as a healthcare professional had a higher prevalence of awareness of CMV than had other women (56% versus 16%, P < .0001). Women who were aware of CMV were most likely to have heard about it from a healthcare provider (54%), but most could not correctly identify modes of CMV transmission or prevention. Among common causes of birth defects and childhood illnesses, women's awareness of CMV ranked last. Conclusion. Despite its large public health burden, few women had heard of congenital CMV, and even fewer were aware of prevention strategies
Cytomegalovirus Infections among African-Americans
<p>Abstract</p> <p>Background</p> <p>Since African-Americans have twice the prevalence of cytomegalovirus (CMV) infections as age-matched Caucasians we sought to determine the ages and possible sources of infection of African-American children.</p> <p>Methods</p> <p>Subjects were 157 African-American healthy children and adolescents and their 113 household adults in Richmond VA. Families completed a questionnaire, provided saliva for antibody testing, and adolescents were interviewed regarding sexual activity.</p> <p>Results</p> <p>Regardless of age CMV seropositivity was not associated with gender, breast feeding, health insurance, sexual activity, or household income, education, or size. In the final regression model, prior CMV infection in adults was over two-fold higher than in children (chi-square = 18.8, p < 0.0001). At one year of age the CMV seropositivity rate was 11% (95%CI = 4% – 24%) and increased 1.8% each year until age 13 years. Between ages 13 and 20 years the CMV seropositivity rate remained between 22% and 33%. For adults, the CMV seropositivity rate was 84% in 21 year olds (95%CI = 69%–.92%). There was no association between CMV infections of the children and their mothers but CMV infections among siblings were associated.</p> <p>Conclusion</p> <p>We observed that African-American children had CMV seroprevalence rates by age 20 years at less than one-half of that of their adult mothers and caregivers. Sibling-to-sibling transmission was a likely source of CMV infections for the children. The next generation of African-American women may be highly susceptible to a primary CMV infection during pregnancy and may benefit from a CMV vaccine.</p
Recruitment of the exotic weakfish at its southernmost limit in Europe: a preliminary assessment.
Since its first record in Europe as an exotic species back in 2009 at the Schelde estuary (Belgium), the weakfish Cynoscion regalis -native from North America East coast- has increased its presence in the Iberian Peninsula waters. Identified for the first time in the Guadalquivir River estuary (2011) and later in the Sado estuary (2014), C. regalis population is increasing in the Gulf of Cadiz and is becoming a fisheries resource. Its introduction into Europe probably occurred through maritime transatlantic trade. Morais et al (2017) suggested that weakfish could have been introduced through multiple independent ballast water release events. The Guadalquivir, Sado and Schelde estuaries show similar transoceanic ship traffic to upstream important commercial ports, supporting multiple direct or secondary transatlantic introductions among European ports. The first genetic studies suggest that C. regalis populations in southern European estuaries are connected and come from a single transoceanic commercial route. Currently, the Gulf of Cadiz maintains a well-established population with frequent catches by artisanal fishing, especially in coastal waters and the estuary, where it is sold in local markets of the surrounding cities.
The population in the area is constituted by mature specimens (ranging from 234 to 453 mm) that are using the estuary as a spawning area, where larvae and juvenile have also been found. In recent years, an increase in the abundance of larvae and juvenile has been observed through monthly samplings in the estuary, which indicates the culmination of the complete life cycle in the Gulf of Cadiz. These findings represent new evidence that the Guadalquivir estuary constitutes a remarkable nursery habitat for this species. This could have effects on native fauna and the ecosystem, which is why it is currently under study and evaluation (EcoInvadiz project) for helping the local Administration to establish, if needed, an appropriate management program
- …