A report on the sea otter, Enhydra lutris L., in California

This report discusses in detail findings and observations of 5 years of research on the sea otter population and its relationship to the nearshore marine environment in California. Initial efforts were directed at providing some relief to the commercial abalone fishery in the Cambria - Point Estero area north of Morro Bay. This fishery has subsequently collapsed along with other commercial and sport abalone and sport crab fisheries throughout the sea otter's range due to continued sea otter foraging. Capturing, tagging and translocation studies, censusing studies, examination of sea otter remains, habitat surveys, food habits observations and studies on otters in captivity provide a broad base of information on the expanding sea otter population in California and its effects on resources utilized by man. Recommendations for sea otter management consistent with esthetic, recreational, and commercial uses of marine resources are included in this report. (95pp.

The Design of Mechanically Compatible Fasteners for Human Mandible Reconstruction

Mechanically compatible fasteners for use with thin or weakened bone sections in the human mandible are being developed to help reduce large strain discontinuities across the bone/implant interface. Materials being considered for these fasteners are a polyetherertherketone (PEEK) resin with continuous quartz or carbon fiber for the screw. The screws were designed to have a shear strength equivalent to that of compact/trabecular bone and to be used with a conventional nut, nut plate, or an expandable shank/blind nut made of a ceramic filled polymer. Physical and finite element models of the mandible were developed in order to help select the best material fastener design. The models replicate the softer inner core of trabecular bone and the hard outer shell of compact bone. The inner core of the physical model consisted of an expanding foam and the hard outer shell consisted of ceramic particles in an epoxy matrix. This model has some of the cutting and drilling attributes of bone and may be appropriate as an educational tool for surgeons and medical students. The finite element model was exercised to establish boundary conditions consistent with the stress profiles associated with mandible bite forces and muscle loads. Work is continuing to compare stress/strain profiles of a reconstructed mandible with the results from the finite element model. When optimized, these design and fastening techniques may be applicable, not only to other skeletal structures, but to any composite structure

Relationship between continuous aerosol measurements and firn core chemistry over a 10-year period at the South Pole

Before ice core chemistry can be used to estimate past atmospheric chemistry it is necessary to establish an unambiguous link between concentrations of chemical species in the air and snow. For the first time a continuous long-term record of aerosol properties (aerosol light scattering coefficient, σsp, and Ångström exponent, å) at the South Pole are compared with the chemical record from a high resolution firn core (∼10 samples per year) covering the period from 1981 to 1991. Seasonal signals in å, associated with winter minima due to coarse mode seasalt and summer maxima due to accumulation mode sulfate aerosol, are reflected in the firn core SO42−/Na+ concentration ratio. Summertime ratios of σsp and aerosol optical depth, τ to corresponding firn core sulfur concentrations are determined and the ‘calibrations’ are applied to sulfur concentrations in snowpits from a previous study. Results show that σsp estimates from snowpit sulfur concentrations are in agreement with atmospheric measurements while τ estimates are significantly different, which is likely due to the lack of understanding of the processes that mix surface air with air aloft

Technology Available to Iowa Teachers through Area Education Agencies

Recently, we have, as a nation, come to realize the vital need for technology literacy among our citizens if we are to cope in a global society. Iowa educational leaders are striving to gain a competitive edge m this area. Working for this edge, the Iowa Department of Education has hired a technology consultant, and guides are being refined to help educators address the topic in their curricula. Standards have been adopted by the State Board of Education relative to telecommunications in Iowa classrooms

Day-length is central to maintaining consistent seasonal diversity in marine bacterioplankton

Marine bacterial diversity is vast, but seasonal variation in diversity is poorly understood. Here we present the longest bacterial diversity time series consisting of monthly (72) samples from the western English Channel over a 6 year period (2003-2008) using 747,494 16SrDNA-V6 amplicon-pyrosequences. Although there were characteristic cycles for each phylum, the overall community cycle was remarkably stable year after year. The majority of taxa were not abundant, although on occasion these rare bacteria could dominate the assemblage. Bacterial diversity peaked at the winter solstice and showed remarkable synchronicity with day-length, which had the best explanatory power compared to a combination of other variables (including temperature and nutrient concentrations). Day-length has not previously been recognised as a major force in structuring microbial communities

LEADING INDICATORS FOR REGIONAL COTTON RESPONSE: STRUCTURAL AND TIME SERIES MODELING RESULTS

Resurging southeastern cotton production compels better cotton acreage forecasts for planning seed, chemical, and other input requirements. Structural models describe leading acreage response indicators, and forecasts are compared time-series models. Cotton price, loan rate, deficiency payments, lagged corn acreage, the PIK program, and previous cotton yield significantly influence response.Crop Production/Industries,

Valuing the biodiversity gains from protecting native plant communities from bitou bush (Chrysanthemoides monilifera subsp rotundata (DC.) T.Norl.) in New South Wales: application of the defensive expenditure method

Valuation of the gains from protection of biodiversity is difficult because the services that provide the benefits do not normally pass through markets where prices can form. But the services sometimes pass through markets where consumers or producers behave in a market-oriented manner, and so the values implicit in this behaviour can be identified and derived. Estimates of the benefits of biodiversity protection are derived from the costs of protecting native plant communities from a major weed in Australia, by following this approach. In 1999, invasion of coastal areas of New South Wales by bitou bush (Chrysanthemoides monilifera subsp. rotundata (DC.) T. Norl.) was listed as a key process threatening native plants under the NSW Threatened Species Conservation Act 1995. In accordance with the Act, the Department of Environment and Climate Change prepared a Threat Abatement Plan (TAP) to reduce the impacts of bitou bush on biodiversity at each threatened site. The costs of protecting sites vary closely with the number of priority native species and communities at each site. Following standard economic assumptions about market transactions, these costs are interpreted to provide values the benefits of protecting extra species, communities, and sites. Key words: Bitou bush, Chrysanthemoides monilifera, threat abatement plan, valuation of biodiversity, benefit-cost analysis, weed control, defensive-expenditure method.Bitou bush, Chrysanthemoides monilifera, threat abatement plan, valuation of biodiversity, benefit-cost analysis, weed control, defensive-expenditure method, Demand and Price Analysis, Environmental Economics and Policy,

LEADING INDICATORS OF REGIONAL COTTON ACREAGE RESPONSE: STRUCTURAL AND TIME SERIES MODELING RESULTS

Resurgent cotton production compels better acreage forecasts for planning seed, chemical, and other input requirements. Structural models describe leading acreage response indicators, and forecasts are compared to time-series models. Cotton price, loan rate, deficiency payments, lagged corn acreage, the PIK program, and previous cotton yield significantly influence cotton acreage response.resurgent cotton production, cotton acreage, Crop Production/Industries,

Classification and analysis of emission-line galaxies using mean field independent component analysis

We present an analysis of the optical spectra of narrow emission-line galaxies, based on mean field independent component analysis (MFICA). Samples of galaxies were drawn from the Sloan Digital Sky Survey (SDSS) and used to generate compact sets of `continuum' and `emission-line' component spectra. These components can be linearly combined to reconstruct the observed spectra of a wider sample of galaxies. Only 10 components - five continuum and five emission line - are required to produce accurate reconstructions of essentially all narrow emission-line galaxies; the median absolute deviations of the reconstructed emission-line fluxes, given the signal-to-noise ratio (S/N) of the observed spectra, are 1.2-1.8 sigma for the strong lines. After applying the MFICA components to a large sample of SDSS galaxies we identify the regions of parameter space that correspond to pure star formation and pure active galactic nucleus (AGN) emission-line spectra, and produce high S/N reconstructions of these spectra. The physical properties of the pure star formation and pure AGN spectra are investigated by means of a series of photoionization models, exploiting the faint emission lines that can be measured in the reconstructions. We are able to recreate the emission line strengths of the most extreme AGN case by assuming the central engine illuminates a large number of individual clouds with radial distance and density distributions, f(r) ~ r^gamma and g(n) ~ n^beta, respectively. The best fit is obtained with gamma = -0.75 and beta = -1.4. From the reconstructed star formation spectra we are able to estimate the starburst ages. These preliminary investigations serve to demonstrate the success of the MFICA-based technique in identifying distinct emission sources, and its potential as a tool for the detailed analysis of the physical properties of galaxies in large-scale surveys.Comment: MNRAS accepted. 29 pages, 24 figures, 3 table

Interpreting the Ionization Sequence in AGN Emission-Line Spectra

We investigate the physical cause of the great range in the ionization level seen in the spectra of narrow lined active galactic nuclei (AGN). Mean field independent component analysis identifies examples of individual SDSS galaxies whose spectra are not dominated by emission due to star formation (SF), which we designate as AGN. We assembled high S/N ratio composite spectra of a sequence of these AGN defined by the ionization level of their narrow-line regions (NLR), extending down to very low-ionization cases. We used a local optimally emitting cloud (LOC) model to fit emission-line ratios in this AGN sequence. These included the weak lines that can be measured only in the co-added spectra, providing consistency checks on strong line diagnostics. After integrating over a wide range of radii and densities our models indicate that the radial extent of the NLR is the major parameter in determining the position of high to moderate ionization AGN along our sequence, providing a physical interpretation for their systematic variation. Higher ionization AGN contain optimally emitting clouds that are more concentrated towards the central continuum source than in lower ionization AGN. Our LOC models indicate that for the objects that lie on our AGN sequence, the ionizing luminosity is anticorrelated with the NLR ionization level, and hence anticorrelated with the radial concentration and physical extent of the NLR. A possible interpretation that deserves further exploration is that the ionization sequence might be an age sequence where low ionization objects are older and have systematically cleared out their central regions by radiation pressure. We consider that our AGN sequence instead represents a mixing curve of SF and AGN spectra, but argue that while many galaxies do have this type of composite spectra, our AGN sequence appears to be a special set of objects with negligible SF excitation.Comment: 57 pages; 18 figures, accepted by MNRA