The relationship between absenteeism and employer-sponsored child care

Given the high loss of revenue due to absenteeism, exploring differentways of managing absenteeism in South African companies, such asfamily-friendly practices, has become important. Establishing onsiteemployer-sponsored child-care facilities is an example of suchpractices.4The purpose of this article is, firstly, to report on exploratory researchthat was done to examine the relationship between absenteeism andon-site employer-sponsored child care. The following dimensionsof absenteeism were examined over a period of one year: absencefrequency, absence severity, attitudinal absence and medicalabsence. The results of two companies, one with a facility and onewithout a facility, were then compared in order to establish therelationship between absenteeism and an on-site facility. Secondly,this article also reports on the relationship between demographicvariables and absenteeism.5The results indicate a significant negative relationship between onsiteemployer-sponsored child care and absenteeism. Regardingthe influence of demographical variables, significant differenceswere found with respect to absenteeism-based marital status andage, while no significant difference was found with respect toabsenteeism based on gender and race.6This article makes a specific contribution to studies on the useof on-site employer-sponsored child-care facilities for managingabsenteeism, specifically in the South African context, and also sheds new light on the influence of demographical variables onabsenteeism

Airborne observations of the tropospheric CO2 distribution and its controlling factors over the South Pacific Basin

Highly precise measurements of CO2 mixing ratios were recorded aboard both the NASA DC-8 and P3-B aircraft during the Pacific Exploratory Mission-Tropics conducted in August-October 1996. Data were obtained at altitudes ranging from 0.1 to 12 km over a large portion of the South Pacific Basin representing the most geographically extensive CO2 data set recorded in this region. These data along with CO2 surface measurements from the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) and the National Institute of Water and Atmospheric Research (NIWA) were examined to establish vertical and meridional gradients. The CO2 spatial distribution in the southern hemisphere appeared to be largely determined by interhemispheric transport as air masses with depleted CO2 levels characteristic of northern hemispheric air were frequently observed south of the Intertropical Convergence Zone. However, regional processes also played a role in modulating background concentrations. Comparisons of CO2 with other trace gases indicated that CO2 values were influenced by continental sources. Large scale plumes from biomass burning activities produced enhanced CO2 mixing ratios within the lower to midtroposphere over portions of the remote Pacific. An apparent CO2 source was observed in the NOAA/ CMDL surface data between 15° N and 15° S and in the lower altitude flight data between 8° N and 8.5° S with a zone of intensity from 6.5° N to 1° S. Inferred from these data is the presence of a Southern Ocean sink from south of 15° S having two distinct zones seasonally out of phase with one another. Copyright 1999 by the American Geophysical Union

Superconductivity Phase Diagram of Na(x)CoO(2).1.3H(2)O

Although the microscopic origin of the superconductivity in high Tc copper oxides remains the subject of active inquiry, several of their electronic characteristics are well established as universal to all the known materials, forming the experimental foundation that all theories must address. The most fundamental of those characteristics is the dependence of the superconducting transition temperature on the degree of electronic band filling. Since the discovery of cuprate superconductivity in 1986 (1), the search for other families of superconductors that might help shed light on the superconducting mechanism of the cuprates has been of great interest. The recent report of superconductivity near 4K in the triangular lattice, layered sodium cobalt oxyhydrate, Na0.35CoO2.1.3H2O, is the best indication that superconductors related to the cuprates may be found (2). Here we show that the superconducting transition temperature of this compound displays the same kind of band-filling behavior that is observed in the cuprates. Specifically, that the optimal superconducting Tc occurs in a narrow range of band filling, and decreases for both underdoped and overdoped materials, in dramatic analogy to the phase diagram of the cuprate superconductors. Our results suggest that characterization of the detailed electronic and magnetic behavior of these new materials may help establish which of the many special characteristics of the cuprates is fundamental to their high Tc superconductivity.Comment: revised, publication information adde

Mechanical behaviour of sustainable concrete with waste ceramic aggregate replacement

Sustainability and material use have been becoming increasingly important in industry and academia in recent years, prompting investigations for ways to improve sustainability in construction materials. Past studies have investigated natural aggregate replacement in concrete with a variety of materials, including recycled concrete, glass, bricks, ceramics, and even automobile tires. These studies have produced varied results. Ceramic materials are a great prospective material for aggregate replacement due to their desirable mechanical properties and availability in waste streams worldwide. This study focusses on coarse aggregate replacement with ceramic tile materials of virgin and waste origins, reaching as high as 100% replacement. To limit the variability experienced in previous studies, great emphasis was placed on limiting parameters tested between series to the physical properties of the replacement ceramic materials alone. Test results thus far have shown that natural coarse aggregate can be replaced in ratios as high as 100%, with only minimal effects on the mechanical properties of the resulting concrete. Compressive, tensile, and flexural strengths have shown minor change, with only a slight increase in elastic modulus. This study shows that ceramic waste material has great potential for use in concrete when a suitable preparation method is used.published_or_final_versio

Chemical transport across the ITCZ in the central Pacific during an El Niño-Southern Oscillation cold phase event in March-April 1999

We examine interhemispheric transport processes that occurred over the central Pacific during the PEM-Tropics B mission (PTB) in March-April 1999 by correlating the observed distribution of chemical tracers with the prevailing and anomalous windfields. The Intertropical Convergence Zone (ITCZ) had a double structure during PTB, and interhemispheric mixing occurred in the equatorial region between ITCZ branches. The anomalously strong tropical easterly surface wind had a large northerly component across the equator in the central Pacific, causing transport of aged, polluted air into the Southern Hemisphere (SH) at altitudes below 4 km. Elevated concentrations of chemical tracers from the Northern Hemisphere (NH) measured south of the equator in the central Pacific during PTB may represent an upper limit because the coincidence of seasonal and cold phase ENSO conditions are optimum for this transport. Stronger and more consistent surface convergence between the northeasterly and southeasterly trade winds in the Southern Hemisphere (SH) resulted in more total convective activity in the SH branch of the ITCZ, at about 6° S. The middle troposphere between 4-7 km was a complex shear zone between prevailing northeasterly winds at low altitudes and southwesterly winds at higher altitudes. Persistent anomalous streamline patterns and the chemical tracer distribution show that during PTB most transport in the central Pacific was from SH to NH across the equator in the upper troposphere. Seasonal differences in source strength caused larger interhemispheric gradients of chemical tracers during PTB than during the complementary PEM-Tropics A mission in September-October 1996. Copyright 2001 by the American Geophysical Union

The Development of Low Cost Sensor technology to provide Augmented Feedback for On-Water Rowing

Investigations to identify ways to improve stroke technique of rowers are on going (Anderson et al 2005). However, the majority of these studies are laboratory based and thus neglect the effects of the oar and water have on the rowing stroke. Traditionally on-water testing has tended to concentrate on the forces produced by the rower at the oar handle, foot stretcher and on boat by the rower but not the actual rowing technique (Hill, 2001). The purpose of this study was to design and develop a system that would provide quantitative feedback of the rowers’ technique on the water. This was accomplished through the integration of low cost electronic sensors, specific software interface and use of wireless technology (Anderson & Collins 2004)

Determinants of Rolling Stock Maintenance Cost in Metros

This study examines the economies of scale and the determinants of rolling stock maintenance costs for 24 urban rail transit operators. The estimates reveal significant returns to scale in maintenance for both per car and per car kilometre. The econometric analysis also provides statistically significant cost elasticities for wages and staff hours, suggesting substitution effects between factors. Staff outsourcing is found to significantly decrease costs, whereas higher levels of fleet availability at the peak and rolling stock failures increase it. The effect of the age of rolling stock and the network is negligible on rolling stock maintenance costs; however, the analysis reveals a downward trend in rolling stock costs among the metros in the CoMET and Nova consortia

Impacts of Unattended Train Operations (UTO) on Productivity and Efficiency in Metropolitan Railways

Urban metro subway systems (metros) around the world are choosing increasing levels of automation for new and existing lines: the global length of metro lines capable of unattended train operation (UTO) is predicted to triple in the next 10 years. Despite significant investment in this technology, empirical evidence for the financial and service quality impacts of UTO in metros remains scarce. This study used questionnaires and semistructured interviews with the Community of Metros and Nova Group benchmarking groups to assemble emerging evidence of how automation affected costs, staffing, service capacity, and reliability. The results from an analysis of data from 23 lines suggested that UTO could reduce staff numbers by 30% to 70%, with the amount of wage cost reduction depending on whether staff on UTO lines were paid more. On the basis of the experience of seven metros, the capital costs of lines capable of UTO were higher, but the internal rate of return had been estimated by two metros at 10% to 15%. Automated lines were capable of operating at the highest service frequencies of up to 42 trains per hour, and the limited available data suggested that automated lines were more reliable. The findings indicated that UTO was a means to a more flexible and reliable operating model that could increase metro productivity and efficiency. The study identified important work needed to understand the impacts of UTO and identify where statistical analyses would add value once sufficiently large data sets became available

Outer zone electrons

Spatial and temporal behavior of high energy trapped electrons in outer zone of magnetospher