421 research outputs found
The organic seed regulations framework in Europe â current status and recommendations for future development
Organic agriculture regulations, in particular European regulation EC 889/2008, prescribe the use of organically produced seed. For many cultivated plants, however, organic seed is often not available. This is mainly because investment in organic plant breeding and seed production has been low in the past. To bridge the gap between organic seed supply and demand, national and European regulations define certain circumstances under which organic producers are permitted to use non-organically produced seed. While the organic sector currently depends on these concessions, they also threaten to impede a further increase in the demand for organic seed, thereby potentially restraining present and future investment in organic seed production and plant breeding. We review the current status of the organic seed regulations framework by analysing key issues such as the role of the national derogation regimes, the role of expert groups, databases and seed prices. Key points are that (a) the situation of the organic seed sector has improved over the last few years; however, (b) reporting on organic seed to the EU by different countries needs to be harmonised; (c) the success of the organic seed sector depends critically on the implementation and improvement of national expert groups; and (d) to protect genetic diversity, the use of local varieties and landraces should not be impeded by organic seed regulations
The Detection of Low Mass Companions in Hyades Cluster Spectroscopic Binary Stars
We have observed a large sample of spectroscopic binary stars in the Hyades
Cluster, using high resolution infrared spectroscopy to detect low mass
companions. We combine our double-lined infrared measurements with well
constrained orbital parameters from visible light single-lined observations to
derive dynamical mass ratios. Using these results, along with photometry and
theoretical mass-luminosity relationships, we estimate the masses of the
individual components in our binaries. In this paper we present double-lined
solutions for 25 binaries in our sample, with mass ratios from ~0.1-0.8. This
corresponds to secondary masses as small as ~0.15 Msun. We include here our
preliminary detection of the companion to vB 142, with a very small mass ratio
of q=0.06+-0.04; this indicates that the companion may be a brown dwarf. This
paper is an initial step in a program to produce distributions of mass ratio
and secondary mass for Hyades cluster binaries with a wide range of periods, in
order to better understand binary star formation. As such, our emphasis is on
measuring these distributions, not on measuring precise orbital parameters for
individual binaries.Comment: 36 pages, 8 figures, accepted for publication in The Astrophysical
Journa
Using natural resource inventory data to improve the management of dryland salinity in the Great Southern, Western Australia
The synoptic assessment of salinity risk and the likely costs and benefits associated with various management options is crucial to natural resource management decision-making in southern Australia. A variety of methods have been proposed and tested for assessing various aspects of salinity risks and costs, but no large region of Australia has ever had a comprehensive risk assessment across the range of biophysical and economic issues with forecasts of the effectiveness of different levels of intervention. This National Land and Water Resources Audit Implementation Project (referred to locally as Salt Scenarios 2020, or SS2020 for short) attempted to provide such an assessment (at a scale of around 1:100,000).
The existing methods of monitoring and predicting salinity (based on variables derived from widely-available Landsat TM data and existing contour data; albeit with improved variable extraction from the DEMs) are being applied to the rest of the agricultural area of WA as part of the Land Monitor Project, funded in part by NHT. Collecting accurate contour data (2-metre) is a major part of the NHT project. This Audit project was proposed to allow other fundamental data sets, and especially groundwater levels from bore-hole data, to be used to significantly improve predictions in lower-rainfall areas as well as refine the predictions in the high rainfall areas.
The Great Southern is an area of considerable economic and environmental value populated by 60,000 people. In 1996, it was estimated that about 30% of the cleared land and associated vegetation and water resources are at risk from becoming salt-affected over the next 30 years unless high-water use farming systems and farm forestry are adopted over large parts of the region(Ferdowsian et al., 1996).
Four key questions arise with respect to the future of this region as affected by dryland salinity:
âąHow large will the problem eventually be under current land practices? How large might it be in the year 2020?
âąWhat is at risk if the area under threat grows that large?
âąTo what degree can we change the eventual extent of salinity with land use alternatives that are both feasible and available?
âąWhat are the costs and benefits of intervening with these alternative land uses?
Ultimately, the SS2020 Project aimed to provide some guidance to state, regional and local planners and managers regarding salinity risk in the Great Southern. The analyses underpinning this guidance were based on similar data employed by NLWRA projects under Theme 2 â Dryland Salinit
Manipulation and removal of defects in spontaneous optical patterns
Defects play an important role in a number of fields dealing with ordered
structures. They are often described in terms of their topology, mutual
interaction and their statistical characteristics. We demonstrate theoretically
and experimentally the possibility of an active manipulation and removal of
defects. We focus on the spontaneous formation of two-dimensional spatial
structures in a nonlinear optical system, a liquid crystal light valve under
single optical feedback. With increasing distance from threshold, the
spontaneously formed hexagonal pattern becomes disordered and contains several
defects. A scheme based on Fourier filtering allows us to remove defects and to
restore spatial order. Starting without control, the controlled area is
progressively expanded, such that defects are swept out of the active area.Comment: 4 pages, 4 figure
Caby Photometry of the Hyades: Comparisons to the Field Stars
Intermediate-band photometry of the Hyades cluster on the Caby system is
presented for dwarf stars ranging from spectral type A through late K. A mean
hk, b-y relation is constructed using only single stars without anomalous
atmospheres and compared to the field stars of the solar neighborhood. For the
F dwarfs, the Hyades relation defines an approximate LOWER bound in the
two-color diagram, consistent with an [Fe/H] between +0.10 and +0.15. These
index-color diagrams follow the common convention of presenting stars with
highest abundance at the bottom of the plot although the index values for the
metal-rich stars are numerically larger. For field F dwarfs in the range [Fe/H]
between +0.4 and -1.0, [Fe/H] = -5.6 delta-hk + 0.125, with no evidence for a
color dependence in the slope. For the G and K dwarfs, the Hyades mean relation
crosses the field star distribution in the two-color diagram, defining an
approximate UPPER bound for the local disk stars. Stars found above the Hyades
stars fall in at least one of three categories: [Fe/H] below -0.7, [Fe/H] above
that of the Hyades, or chromospherically active. It is concluded that, contrary
to the predictions of model atmospheres, the hk index for cool dwarfs at a
given color hits a maximum value for stars below solar composition and, with
increasing [Fe/H] above some critical value, declines. This trend is
consistent, however, with the predictions from synthetic indices based upon
much narrower Ca filters where the crossover is caused by the metallicity
sensitivity of b-y.Comment: 13 pages, 9 eps figures, 1 tex table, 1 ascii tabl
On the determination of oxygen abundances in chromospherically active stars
We discuss oxygen abundances derived from [O I] 6300 and the O I triplet in
stars spanning a wide range in chromospheric activity level, and show that
these two indicators yield increasingly discrepant results with higher
chromospheric/coronal activity measures. While the forbidden and permitted
lines give fairly consistent results for solar-type disk dwarfs, spuriously
high O I triplet abundances are observed in young Hyades and Pleiades stars, as
well as in individual components of RS CVn binaries (up to 1.8 dex). The
distinct behaviour of the [O I]-based abundances which consistently remain
near-solar suggests that this phenomenon mostly results from large departures
from LTE affecting the O I triplet at high activity level that are currently
unaccounted for, but also possibly from a failure to adequately model the
atmospheres of K-type stars. These results suggest that some caution should be
exercised when interpreting oxygen abundances in active binaries or young open
cluster stars.Comment: 8 pages, accepted for publication in A&
International Childrenâs Rights: Reflections on a Complex, Dynamic, and Relatively Young Area of Law
This chapter reflects on the aim of the International Childrenâs Rights volume to provide those wishing to study, research, and practice international childrenâs rights law with a contemporary and comprehensive legal text. It recaps on the themes that emerged from the process of commissioning and editing the various contributions from some of the worldâs leading and emerging legal scholars in the area of childrenâs rights. It marks the progress that has been made in the implementation of childrenâs rights law and the many challenges that still exist in the implementation of the CRC and associated international instruments. It notes that legal scholarship in the field of childrenâs rights is still developing and that, although multidisciplinary research and analysis is valuable, it is important to reaffirm childrenâs rights as a field of law and legal practice. International childrenâs rights is a complex, dynamic, and relatively young area of law. As the contributions to the collection show, it is diverse and evolving, with many new aspects and issues worthy of analysis and scrutiny. This chapter encapsulates the aspiration of the volume editors that the book contribute to the scrutiny of the legal implications of the CRC, recognizing the unique features of international childrenâs rights law, adding to the ongoing development of this important area of law.Effective Protection of Fundamental Rights in a pluralist worl
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