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

Outer zone electrons

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

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

Identifying as in, out, or sexually inexperienced: Perception of sex-related personal disclosures

The current research explored perceptions of disclosing the information of "I am gay", "I am heterosexual", and "I am a virgin" to a variety of audiences. Participants were 842 undergraduate students who evaluated the valence of each disclosure, listed the associated feelings, and rated the comfort of disclosing such information to various audiences (e.g., a family member, online community). Participants rated the statement consistent with their own sexual orientation as being significantly more positive. No significant difference was found between gay and heterosexual participants’ ratings about disclosing virginity, and disclosure of virginity status was ranked as the most uncomfortable of the three disclosures. Both heterosexual and gay respondents indicated it would be more comfortable to disclose a heterosexual orientation than a gay one, despite gay participants rating a gay orientation as more positive. The audience ranked most to least comfortable to disclose varied with sexual orientation and disclosure content. Perceived closeness of audience was correlated with comfort of disclosure for known (family, partner, friend, colleague) audiences, but not professional (counsellor) or unknown (stranger, online) audiences. These findings are discussed with reference to the literature on “coming out”, addressing important differences in the perceptions of in-group and out-group disclosure of sexual orientation, and sex-related personal information

Numerical Hermitian Yang-Mills Connections and Kahler Cone Substructure

We further develop the numerical algorithm for computing the gauge connection of slope-stable holomorphic vector bundles on Calabi-Yau manifolds. In particular, recent work on the generalized Donaldson algorithm is extended to bundles with Kahler cone substructure on manifolds with h^{1,1}>1. Since the computation depends only on a one-dimensional ray in the Kahler moduli space, it can probe slope-stability regardless of the size of h^{1,1}. Suitably normalized error measures are introduced to quantitatively compare results for different directions in Kahler moduli space. A significantly improved numerical integration procedure based on adaptive refinements is described and implemented. Finally, an efficient numerical check is proposed for determining whether or not a vector bundle is slope-stable without computing its full connection.Comment: 38 pages, 10 figure

Influence of regional-scale anthropogenic emissions on CO2 distributions over the western North Pacific

We report here airborne measurements of atmospheric CO2 over the western North Pacific during the March-April 2001 Transport and Chemical Evolution over the Pacific (TRACE-P) mission. The CO2 spatial distributions were notably influenced by cyclogenesis-triggered transport of regionally polluted continental air masses. Examination of the CO2 to C2H2/CO ratio indicated rapid outflow of combustion-related emissions in the free troposphere below 8 km. Although the highest CO2 mixing ratios were measured within the Pacific Rim region, enhancements were also observed further east over the open ocean at locations far removed from surface sources. Near the Asian continent, discrete plumes encountered within the planetary boundary layer contained up to 393 ppmv of CO2. Coincident enhancements in the mixing ratios of C2Cl4, C2H2, and C2H4 measured concurrently revealed combustion and industrial sources. To elucidate the source distributions of CO2, an emissions database for Asia was examined in conjunction with the chemistry and 5-day backward trajectories that revealed the WNW/W sector of northeast Asia was a major contributor to these pollution events. Comparisons of NOAA/CMDL and JMA surface data with measurements obtained aloft showed a strong latitudinal gradient that peaked between 35° and 40°N. We estimated a net CO2 flux from the Asian continent of approximately 13.93 Tg C day-1 for late winter/early spring with the majority of the export (79%) occurring in the lower free troposphere (2-8 km). The apportionment of the flux between anthropogenic and biospheric sources was estimated at 6.37 Tg C day-1 and 7.56 Tg C day-1, respectively

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

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