A spectral optimally interpolated mean sea surface from satellite radar altimetry

 A technique is presented for the development of a high-precision and high-resolution mean sea surface model utilising radar altimetric sea surface heights extracted from the geodetic phase of the European Space Agency (ESA) ERS-1 mission. The methodology uses a cubic-spline fit of dual ERS-1 and TOPEX crossovers for the minimisation of radial orbit error. Fourier domain processing techniques are used for spectral optimal interpolation of the mean sea surface in order to reduce residual errors within the initial model. The EGM96 gravity field and sea surface topography models are used as reference fields as part of the determination of spectral components required for the optimal interpolation algorithm. A comparison between the final model and 10 cycles of TOPEX sea surface heights shows differences of between 12.3 and 13.8 cm root mean square (RMS). An un-optimally interpolated surface comparison with TOPEX data gave differences of between 15.7 and 16.2 cm RMS. The methodology results in an approximately 10-cm improvement in accuracy. Further improvement will be attained with the inclusion of stacked altimetry from both current and future missions. Received: 22 December 1999 / Accepted: 6 November 2000     

Plastic particles in three procellariiform seabirds from the Benguela Current,South Africa

Small plastic particles were found in White-chinned Petrels and Great Shearwaters collected in the Benguela Current, but not in Sooty Shearwaters collected in the same region. The origin of these particles is unclear. They may have originated in the Antarctic or subantarctic, or, in the case of those found in the Great Shearwaters, in the North Atlantic. Plastic particle pollution of seabirds is an increasing phenomenon, and of concern in view of the possible damage caused to the birds. As such it should be carefully monitored.     

Need for and access to supportive services in the child welfare system

The purpose of this paper is to examine how geographical availability of social services is related to foster care entry rates and referrals for child maltreatment investigations. The primary concerns are to (1) determine locations across Los Angeles County where the availability of social services is low but display a high need for those services and (2) begin to examine how the geographic distribution of social services is related to rates of referrals and foster care entries in child maltreatment. Archival data for all 288 zip codes within Los Angeles County were collected on rates of referrals, foster care entries, location and types of social service agencies, and zip code demographics. Data were analyzed using point process models and spatial regressions. Higher densities of child welfare services in local areas (for referrals) and lagged areas (for referrals and foster care entries) were related to lower rates of child maltreatment. The density of housing and housing-related services was negatively related to referrals in local areas and foster care entry rates in lagged areas. Areas with higher densities of substance abuse and domestic violence service agencies had significantly higher rates of both Child Protective Services referrals and entries into foster care in local areas. While the total density of child welfare services within and surrounding zip code areas is related to lower rates of referrals and foster care entries, the findings are less clear about what those specific services are. Living in and around “resource rich” zip codes may reduce rates of child maltreatment.     

Are input controls required in individual transferable quota fisheries to address ecosystem based fisheries management objectives?

This study examined the use of Individual Transferable Quotas (ITQs) to effectively manage fishing impacts on all ecosystem components, as required under Ecosystem Based Fisheries Management (EBFM) principles. A consequence of changing from input controls to output-based (catch) management is that the control of the regulating authority tends to be reduced, which may affect the outcomes for ecosystem management. This study reviewed the use of input controls across six fishing methods in 18 ITQ fisheries, which have been independently accredited as ecologically sustainable by the Marine Stewardship Council (12 fisheries) or under Australian environmental legislation for Wildlife Trade Operation (six fisheries). Input controls were retained across a range of ITQ fisheries, with non-selective fisheries such as trawl, gillnet and line employing more input controls than selective fisheries such as purse-seine, pot/trap and dredge. Further case-studies confirmed the widespread and recent use of input controls (spatial and temporal closures) with the aim of managing ecosystem impacts of fishing. The retention of input controls, particularly closures affects the security (quality of title) characteristic of the fishing use right and the theoretical ability of fishers to manage their right for their future benefit. The security characteristic is weakened by closures through loss of access, which undermines industry trust and incentive for long-term decision making. By reducing the security of ITQs, individual fisher incentives and behaviour may separate from societal objectives for sustainability, which was one of the foremost reasons for introducing ITQ management.     

Secular and orbital variability of Cir X-1 observed in optical spectra

We have observed variations in the optical emission lines from the X-ray binary Circinus X-1. These variations may be attributed both to orbital variations and to long term secular changes in line strength. We have detected double-peaked H α emission lines on two occasions, providing the first direct evidence for an accretion disc in the system. The separation of the peaks was different on the two occasions, suggesting that the disc might have a different size. The equivalent width of the emission lines dropped by more than a factor of three between 1999 and 2000; this continues the trend seen in earlier data, so that the H α equivalent width has now declined by a factor of 20 since 1976. The emission lines do not appear to show signature of orbital motion, except for the data taken near phase 0, which show a significant velocity shift.
We have observed an absorption component to the He  i lines on one occasion. We suggest that, unlike the P Cygni profiles seen in X-ray spectra, this absorption does not arise in the accelerating zone of a radiatively driven wind. Instead, the absorption arises in material previously ejected from the system. It was only seen on this one occasion because the strength of the emission line had dropped dramatically.     

Making Sense of Claims across Institutional Divides: critical PGIS and mapping customary land in Timor-Leste

This article explores land-tenure issues faced by Timor-Leste, specifically with reference to customary land, and the significance of mapping in resolving those difficulties. A critical review is undertaken of the pitfalls of Indigenous mapping and applications of Participatory Geographic Information Systems (PGIS) to achieve sensitive and empowering outcomes for customary groups seeking land claims. A methodology for mapping customary land in Timor-Leste is described and an analysis of the author's on-the-ground research is presented. Although the importance of customary institutions for rural land management across Timor-Leste is ascertained, this article does not advance a definitive land rights framework for the country or prescribe national mapping of customary areas. Instead, it argues for a mapping methodology to support land-use decision-making that can make sense of Indigenous knowledge and appropriate cultural practices in rural land-use claims. Identified as crucial in the process is the equal value attributed to evidence presented in myriad forms that may act as key information bridges across epistemological divides and knowledges. PGIS is a potentially important tool for resolving land-use conflicts in rural Timor-Leste when resolution occurs within a formalised institutional framework.     

Chloride loading in the South Fork of the Shenandoah River,Virginia, U.S.A.

Loading trends and sources of CI^– in the South Fork of the Shenandoah River, Virginia were analyzed for the period 1929–1982. CI^– has increased from approximately 2 mg/L (2,776 tons/yr) to over 10 mg/L (14,256 tons/yr). Natural CI^– is estimated to be 1.01 mg/L (1,388 tons/yr) with precipitation providing 0.99 mg/L and rocks 0.02 mg/L. From 1929 to 1949 CI^– concentrations were relatively constant and independent of discharge, conforming to the Type II curve of Davis and Zobrist (1978), indicative of natural or relatively uncontaminated streams. Since 1952 CI^– concentrations increased exponentially as river discharge decreases conforming to the Type I curve of Davis and Zobrist for polluted streams. Since 1965 anthropogenic CI^– loading at 12,868 tons/yr has remained relatively constant. Four major sources contribute 92.2 percent (11,871 tons/yr) of the anthropogenic CI^–: (1) deicing salts—4,149 tons/yr, (2) domestic sewage—3,015 tons/yr, (3) livestock and poultry wastes—2,458 tons/yr, and (4) commercial fertilizers—2,249 tons/yr.     

The study of fluorescence characteristics and biochemical composition of a marine diatom Thalassiosira pseudonana 3H in light and dark cycles-Ⅱ. The effects of light

The effects of light on the fluorescence characteristics and biochemical composition of a marine diatom Tha-lassiosira pseudonana in light and dark cycles were investigated with semi-continuous culture. The results indicate that, with the increase of growing light intensity, DCMU enhanced fluorescence yield (Fd/Chl), enhanced fluorescence ratio (Fd/F) , cellular carbohydrate content. carbohydrate/chlorophyll a and carbohydrate/protein ratio increased , but the fluorescence yield and cellular chlorophyll a content decreased; The protein content declined with the increase of light intensity in the range of 10- 100 μmol/ (m2·s) and increased at higher than 100 μmol/ (m2·s). Sampling time during the day had great effect on the relationships between growing light intensity and cellular chlorophyll a , carbohydrate content , carbohydrate/chlorophyll a and carbohydrate/protein ratio.