6 research outputs found
Shortfalls and Solutions for Meeting National and Global Conservation Area Targets
Governments have committed to conserving greater than or equal to 17% of terrestrial and greater than or equal to 10% of marine environments globally, especially areas of particular importance for biodiversity through ecologically representative Protected Area (PA) systems or other area-based conservation measures , while individual countries have committed to conserve 3-50% of their land area. We estimate that PAs currently cover 14.6% of terrestrial and 2.8% of marine extent, but 59-68% of ecoregions, 77-78% of important sites for biodiversity, and 57% of 25,380 species have inadequate coverage. The existing 19.7 million km super(2) terrestrial PA network needs only 3.3 million km super(2) to be added to achieve 17% terrestrial coverage. However, it would require nearly doubling to achieve, cost-efficiently, coverage targets for all countries, ecoregions, important sites, and species. Poorer countries have the largest relative shortfalls. Such extensive and rapid expansion of formal PAs is unlikely to be achievable. Greater focus is therefore needed on alternative approaches, including community- and privately managed sites and other effective area-based conservation measures
SDSS-IV MaNGA IFS Galaxy Survey --- Survey Design, Execution, and Initial Data Quality
The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy (IFS) for 10K nearby galaxies at a spectral resolution of R ~ 2000 from 3622 − 10, 354Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. We describe how these science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (Re) while maximizing spatial resolution. About 2/3 of the sample is covered out to 1.5Re (Primary sample), and 1/3 of the sample is covered to 2.5Re (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specifically, the point spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r-band signal-to-noise ratio is ~ 73 per 1.4Å pixel for spectra stacked between 1–1.5 Re. Measurements of various galaxy properties from the first year data show that we are meeting or exceeding the defined requirements for the majority of our science goals
An introduction to the Australian and New Zealand flux tower network : OzFlux
OzFlux is the regional Australian and New Zealand flux tower network that aims to provide a continental-scale national research facility to monitor and assess trends, and improve predictions, of Australia's terrestrial biosphere and climate. This paper describes the evolution, design, and current status of OzFlux as well as provides an overview of data processing. We analyse measurements from all sites within the Australian portion of the OzFlux network and two sites from New Zealand. The response of the Australian biomes to climate was largely consistent with global studies except that Australian systems had a lower ecosystem water-use efficiency. Australian semi-arid/arid ecosystems are important because of their huge extent (70 %) and they have evolved with common moisture limitations. We also found that Australian ecosystems had a similar radiation-use efficiency per unit leaf area compared to global values that indicates a convergence toward a similar biochemical efficiency. The two New Zealand sites represented extremes in productivity for a moist temperate climate zone, with the grazed dairy farm site having the highest GPP of any OzFlux site (2620 gC m−2 yr−1) and the natural raised peat bog site having a very low GPP (820 gC m−2 yr−1). The paper discusses the utility of the flux data and the synergies between flux, remote sensing, and modelling. Lastly, the paper looks ahead at the future direction of the network and concludes that there has been a substantial contribution by OzFlux, and considerable opportunities remain to further advance our understanding of ecosystem response to disturbances, including drought, fire, land-use and land-cover change, land management, and climate change, which are relevant both nationally and internationally. It is suggested that a synergistic approach is required to address all of the spatial, ecological, human, and cultural challenges of managing the delicately balanced ecosystems in Australasia
Spectral density constraints on wireless communication
Environmental exposure to man-made electromagnetic field (EMF) has been rising as modern technologies
have grown and changed in social behaviour have generated more synthetic sources. For the safety of human
health, EMF levels need to be regulated. The level of EMF should be well below levels where there might be
harm, hence we do not expect to see any health effects at these levels. Current regulations fail to place a strict
limit on EMF in situations where multiple nearby devices transmit simultaneously. The way these regulations
are expressed needs great care because it will have an effect on the design of wireless communication systems.
In this paper, it is argued that transmitted power constraints on wireless communication devices should be
expressed in a different way, namely that devices should limit the EMF spectral density that they generate to
the difference between the maximum allowed, by the standard, and the amount currently present, as measured
by the device, in the spectral region where it is active. Note that the limit on EMF should be expressed in
terms of its EMF spectral density rather than as a total EMF over each of a series of separate bands. If all
devices limit their own EMF spectral density, in the spectral region where they are active, in such a way that
total EMF spectral density is below the regulated limit in that region, then it is certain that the aggregate EMF
spectral density will be below the regulated limit at all frequencies