An aromatase inhibitor and tamoxifen decrease plasma levels of o,p'-DDT and its metabolites in Nile tilapia (Oreochromis niloticus)

The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p' -DDT and its metabolites, o,p'-DDD and o,p'-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p'-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p'-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p'-DDT had significantly higher levels of o,p'-DDT compared with males. Interestingly, females and males treated concomitantly with o,p'-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p'-DDT (about 50%) compared with fish treated with only o,p'-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p'-DDT.     

山西铝土矿床成矿物质来源

山西铝土矿矿石中鲕、豆、碎屑等组构均具红土性质，结合化学成分特征、稀土元素特征、氧同住素特征、锆石等副矿物特征及含矿岩系底部岩层与下伏中奥陶纪灰岩关系和矿床分布与古陆、古岛的依赖关系等方面分析，铝土矿的成矿物质多是异源的，多为古陆上的铝硅酸盐岩红土风化产物，经流水以机械碎屑形式被搬运至海盆，沉积成矿     

Web Use in Geographical and Environmental Education: An International Survey at the Primary and Secondary Level

This article aims to study Web use and Web-based co-operation and collaboration in geographical and environmental education at the primary and secondary level around the world. Recent trends and future opportunities and challenges are taken into account. The theoretical part of the study considers Web use and different forms of Web-based co-operation. Web use and co-operation in education are classified as co-operative learning, collaborative learning or communal learning. Web use in geographical and environmental education is noted to be growing in significance. Web-based co-operation at any level of intensity is associated with many opportunities and challenges. The empirical part of this study involves a survey of geographical and environmental education researchers in various countries about their views of Web use in education. The results of this survey indicate that the Web in general finds minimal use in geographical and environmental education. As access to the Web is limited and only some pupils can use it, co-operation, particularly collaborative learning on the Web, is still rare in geographical and environmental education. The most often used application is e-mail. Researchers recognise the potential of the Web to enhance local, national and international co-operation, and to facilitate a better understanding of geographical and environmental issues at the grass-root level. Web-based learning can also help to increase and deepen the pupils' cultural understanding. Before that, however, problems in access, costs and teacher training must be solved. This revised version was published online in August 2006 with corrections to the Cover Date.     

Detecting the stepwise propagation of the Eastern Sicily thrust belt (Italy): insight from thermal and thermochronological constraints

An extensive dataset of vitrinite reflectance, FTIR parameters on organic matter, illite content in mixed layers illite‐smectite, apatite fission tracks and U‐Th/He dating has been used to reconstruct the stepwise propagation of the Eastern Sicily fold‐and‐thrust belt during Late Palaeogene and Neogene times. The results indicate that the fold‐and‐thrust belt is divisible into two levels of thermal maturity. These levels consist of a less evolved level of thermal maturity that records limited sedimentary burial and minor heating, and a more evolved level of thermal maturity that indicates tectonic burial and exhumation at different times. Deformation and exhumation of shallowly buried units are linked to wedge forward propagation by low‐angle thrusts, whereas the evolution of deeply buried units is associated with tectonic imbrications by duplex formation and steep thrusts. The two tectonic styles alternate during evolution of the fold‐and‐thrust belt under low erosion rates.     

The Byers Basin: Jurassic-Cretaceous tectonic and depositional evolution of the forearc deposits of the South Shetland Islands and its implications for the northern Antarctic Peninsula

ABSTRACT

This paper addresses the Jurassic–Cretaceous stratigraphic evolution of fore-arc deposits exposed along the west coast of the northern Antarctic Peninsula. In the South Shetland Islands, Upper Jurassic deep-marine sediments are uncomformably overlain by a Lower Cretaceous volcaniclastic sequence that crops out on Livingston, Snow and Low islands. U-Pb zircon ages are presented for the upper Anchorage Formation (153.1 ± 1.7 Ma) and the Cape Wallace granodiorite of Low Island (137.1 ± 1.7 Ma) as well as ⁴⁰Ar/³⁹Ar ages of 136–139 Ma for Low Island andesites. Data are also presented for a U-Pb age of 109.0 ± 1.4 Ma for the upper volcanic succession of Snow Island. In combination with published stratigraphy, these data provide a refined chrono- and litho-stratigraphic framework for the deposits herein referred to as the Byers Basin. Tentative correlation is explored with previously described deposits on Adelaide and Alexander islands, which could suggest further continuation of the Byers Basin towards the south. We also discuss possible correlation of the Byers Basin with the Larsen Basin, a sequence that shows the evolution of foreland to back-arc deposits more or less contemporaneously with the fore-arc to intra-arc evolution of the Byers Basin.     

“Pandora box” — Matrix in the calculus of observations

Summary If the condition R(A)=k(n), whereA is the design matrix of the type n × k and k the number of parameters to be determined, is not satisfied, or if the covariance matrixH is singular, it is possible to determine the adjusted value of the unbiased estimable function of the parameters f(), its dispersion D( (x)) and ² as the unbiased estimate of the value of ² by means of an arbitrary g-inversion of the matrix . The matrix , because of its remarkable properties, is called the Pandora Box matrix. The paper gives the proofs of these properties and the manner in which they can be employed in the calculus of observations.     

A spar buoy design for oceanographic data telemetry

Abstract

The design of a spar buoy, employed as one component of a current monitoring system deployed during 1980 in Davis Strait, and some of its response characteristics to ocean waves are presented. The buoy was 36.5 ft (11.13 m) in length with upper and lower masts 0.5ft (15.2 cm) in diameter and buoyancy hulls, centrally located, 2 ft (61.0 cm) in diameter. Power for the system was supplied from lead‐acid batteries in a ballast tank on the lower end. Telemetry electronics were located in a 1‐ft (30.5‐cm) diameter case on the upper end, below the antenna. The buoy weighed about 1,635 lb (746kg) and could be man‐handled at sea with relatively light lifting equipment. It had a damped period of 16s and a significant heave response of about 62% of the significant wave height of the forcing spectrum. Scale model tests indicated that the buoy would be operational in heavy sea swell up to about 20ft in height with pitching angles of less than 10° off vertical. Observations at sea have shown that the buoy followed swell waves better than the 62% heave response figure would imply and had negligible pitching motions except during severe storms. The design was judged to be successful in providing a stable base for VHF transmission and is recommended for use in other applications.     

The atmospheric signature of Io's Prometheus plume and anti-jovian hemisphere: evidence for a sublimation atmosphere

Using the Hubble Space Telescope's Space Telescope Imaging Spectrograph we have obtained for the first time spatially resolved 2000-3000 Å spectra of Io's Prometheus plume and adjoining regions on Io's anti-jovian hemisphere in the latitude range 60° N-60° S, using a 0.1″ slit centered on Prometheus and tilted roughly 45° to the spin axis. The SO₂ column density peaked at 1.25×10¹⁷ cm⁻² near the equator, with an additional 5×10¹⁶ cm⁻² enhancement over Prometheus corresponding to a model volcanic SO₂ output of 10⁵ kg s⁻¹. Apart from the Prometheus peak, the SO₂ column density dropped fairly smoothly away from the subsolar point, even over regions that included potential volcanic sources. At latitudes less than ±30°, the dropoff rate was consistent with control by vapor pressure equilibrium with surface frost with subsolar temperature 117.3±0.6 K, though SO₂ abundance was higher than predicted by vapor pressure control at mid-latitudes, especially in the northern hemisphere. We conclude that, at least at low latitudes on the anti-jovian hemisphere where there are extensive deposits of optically-thick SO₂ frost, the atmosphere is probably primarily supported by sublimation of surface frost. Although the 45° tilt of our slit prevents us from separating the dependence of atmospheric density on solar zenith angle from its dependence on latitude, the pattern is consistent with a sublimation atmosphere regardless of which parameter is the dominant control. The observed drop in gas abundance towards higher latitudes is consistent with the interpretation of previous Lyman alpha images of Io as indicating an atmosphere concentrated at low latitudes. Comparison with previous disk-resolved UV spectroscopy, Lyman-alpha images, and mid-infrared spectroscopy suggests that Io's atmosphere is denser and more widespread on the anti-jovian hemisphere than at other longitudes. SO₂ gas temperatures were in the range of 150-250 K over the majority of the anti-jovian hemisphere, consistent with previous observations. SO was not definitively detected in our spectra, with upper limits to the SO/SO₂ ratio in the range 1-10%, roughly consistent with previous observations. S₂ gas was not seen anywhere, with an upper limit of 7.5×10¹⁴ cm⁻² for the Prometheus plume, confirming that this plume is significantly poorer in S₂ than the Pele plume (S₂ /SO₂<0.005, compared to 0.08-0.3 at Pele). In addition to the gas absorption signatures, we have observed continuum emission in the near ultraviolet (near 2800 Å) for the first time. The brightness of the observed emission was directly correlated with the SO₂ abundance, strongly peaking in the equatorial region over Prometheus. Emission brightness was modestly anti-correlated with the jovian magnetic latitude, decreasing when Io intersected the torus centrifugal equator.     

Vulnerability of Aboriginal health systems in Canada to climate change

Climate change has been identified as potentially the biggest health threat of the 21st century. Canada in general has a well developed public health system and low burden of health which will moderate vulnerability. However, there is significant heterogeneity in health outcomes, and health inequality is particularly pronounced among Aboriginal Canadians. Intervention is needed to prevent, prepare for, and manage climate change effects on Aboriginal health but is constrained by a limited understanding of vulnerability and its determinants. Despite limited research on climate change and Aboriginal health, however, there is a well established literature on Aboriginal health outcomes, determinants, and trends in Canada; characteristics that will determine vulnerability to climate change. In this paper we systematically review this literature, using a vulnerability framework to identify the broad level factors constraining adaptive capacity and increasing sensitivity to climate change. Determinants identified include: poverty, technological capacity constraints, socio-political values and inequality, institutional capacity challenges, and information deficit. The magnitude and nature of these determinants will be distributed unevenly within and between Aboriginal populations necessitating place-based and regional level studies to examine how these broad factors will affect vulnerability at lower levels. The study also supports the need for collaboration across all sectors and levels of government, open and meaningful dialogue between policy makers, scientists, health professionals, and Aboriginal communities, and capacity building at a local level, to plan for climate change. Ultimately, however, efforts to reduce the vulnerability of Aboriginal Canadians to climate change and intervene to prevent, reduce, and manage climate-sensitive health outcomes, will fail unless the broader determinants of socio-economic and health inequality are addressed.