4,906 research outputs found
Surface-brightness profiles of dwarf galaxies in the NGC 5044 Group: Implications for the luminosity-shape and scalelength-shape relationships as distance indicators
No full textIn a recent paper, which presents CCD photometry for fifteen dwarf and intermediate early-type galaxies in the NGC 5044 Group. it has been claimed that "a few relatively bright galaxies with ''convex" profiles destroy :he known relation between total magnitude and the "shape" parameter... thus ruling out the use of this relation as a distance indicator for individual galaxies". In the same paper, further reasons were cited supposedly "limiting also its use as a distance indicator for groups of galaxies''. We demonstrate that none of the three relatively bright galaxies cited as possessing "convex" profiles actually has a convex profile, and that one of these objects should be excluded because it is a late-type galaxy. Of the two remaining objects, one has an anomalous profile shape whilst the other is brighter than one might expect from its colour alone, However, we show that all of the other issues raised have already been accounted for by Young & Currie (1994. 1995 & 1998). The main implications of the new observations are: (1) that the case of one galaxy with an anomalous profile shape, N42, highlights the need for some a priori criteria to be defined in order to establish objectively which objects are not suitable for distance determinations: and (2) on the basis of another unusual galaxy, N50. colour has now been shown to be a poorer discriminant between objects of the same profile shape and scalelength (but of different central surface brightness) than previously thought. How significant this latter problem is depends on how common N50-like objects are. This consideration reinforces the case for always using the more general scalelength-shape relationships of Young & Currie (1995) in preference to the luminosity-shape one of Young & Currie (1994). Reassuringly, through a re-analysis of the same CCD photometry, we find that NGC 5044 Group galaxies observe a tight scalelength-shape relationship. This finding supports the view that the scalelength-shape relationship is a viable distance indicator
Self-compression of 4.9 µm pulses to sub-40 fs with 2 mJ energy in Zinc Sulfide
No full textNonlinear self-compression of few-cycle multi-mJ pulses at 4.9 µm in ZnS is presented. 80 fs input pulses are compressed to 37 fs with 2.1 mJ energy at a 1 kHz repetition rate. © 2024 The Author(s
Export of nitrogen and phosphorus from artificially drained dairy pastures in the Hauraki Plains
No full textThis work forms part of the MBIE-funded Transfer Pathways Programme, which targets quantification of the pathway-specific transfers of nitrogen (N) and phosphorus (P) from the land to receiving waters, taking lag times and attenuation potentials of the specific pathways into account. Artificial drainage is one of the shallowest and fastest transfer pathways from the paddock to surface waters. N and P lost from the root zone can reach surface waters essentially un-attenuated, as the P-adsorption and denitrification potentials for N removal existing in the subsurface are largely bypassed.
We report here on the N and P exports via subsurface drainage measured during the first season of our monitoring programme at two Hauraki Plains field sites with relatively high land use intensities. Subsurface drains at both dairy farms are installed in approx. 0.7 m depth and both field sites have similar ‘catchment areas’ (Waharoa 3.9 ha and Tatuanui 4.3 ha). The field sites have only relatively small differences in soil profile properties, but more pronounced differences in the characteristics of the underlying deposits. As a result, the partitioning of the total water and nutrient flows between shallow lateral flows through the subsurface drains and vertical recharge into the underlying deeper groundwater system is distinctly different between the two sites.
At the Waharoa site, the soil profile becomes saturated from the “top down” due to low permeability zones within the soil profile, with drainage discharge beginning eight weeks earlier (mid-May) than at the Tatuanui site (mid-July). A shallow groundwater table seasonally rising into a relatively permeable soil zone is suspected to cause the wetting up of the soil profile from the “bottom up” at Tatuanui.
The initial nitrate-N concentrations in Tatuanui drainage water were low (< 1 mg/l NO₃-N). However, two weeks later nitrate-N concentrations had increased to nearly 9 mg/l NO₃-N coinciding with peak drainage flow rates of 10 l/s. The initially low nitrate-N concentrations are considered to be due to mixing occurring below the depth of the drainage pipes of the leachate draining from the soil zone with underlying reduced shallow groundwater. This reduced groundwater is due to decomposing peat material residing below the mineral soil in approx. 1 to 10.5 m depth. Once the groundwater table has risen to the depth of the subsurface drainage pipes, the water percolating through the soil zone in response to excess rain is directly intercepted by these drainage pipes. The strong increase in nitrate-N concentrations is thought to be a result of the soil zone leachate entering the drains before any significant mixing with the underlying reduced groundwater can occur. At Tatuanui nitrate-N2 represented 76% of the total-N discharged in the drainage waters over the 2016 drainage season, while NH₄-N and organic N made up the remainder in nearly equal proportions. At the Waharoa site, nitrate-N made up 86% of the total-N exported, however NH₄-N only contributed approx. 1%, with organic N contributing the remaining 13%. The highest total-P concentrations at Tatuanui occurredin the early and mid-part of the drainage season at the peak flows in the drainage hydrograph. Again, his is considered to be due to the influence of the reduced groundwater residing in the peat layer underlying the mineral soil at the Tatuanui site. Once the drainage was dominated by soil leachate, the total-P concentrations were generally low (< 0.004 mg/l). At Tatuanui and Waharoa, dissolved-P represented approx. 58% of the total-P measured, and dissolved reactive P accounted for 27% of total-P.
As the subsurface system is considered to be effectively sealed at the Tatuanui site, with very little groundwater flow occurring, the artificial drainage pathway is considered to be almost exclusively the pathway for contaminant export from this site. In contrast, at the Waharoa site it appears that the shallow groundwater is probably an important contaminant export pathway additionally to the artificial drainage pathway
A framework for understanding the linkages between land and water quality impacts
No full textDifferent soils, landscapes and water pathways vary at a range of spatial and temporal scales in their propensity to yield, transport and attenuate contaminants. This affects a land's suitability t various types and intensities of use. For instance, one national-scale study has found that , on average, 55% of nitrogen (N) and phosphorus (P) lost from productive land uses in New Zealand are attenuated as they make their way through catchments to the sea, but proportions attenuated vary widely across and between landscapes. Thus, the limit setting processes and the actual limits applied to land uses by regulators under the NPS-FM (National Policy Statement for Freshwater Management) to safeguard the life-supporting capacity of freshwaters and the associated health of people and communities need to take into account these differences in transport and attenuation between contaminant sources and sites where water quality attributes are defined. The Sources & Flows programme in the Our Land & Water National Science Challenge aims to develop a framework that will synthesise our existing knowledge of contaminant sources and pathways to predict the spatial and temporal effect of these attenuating factors on contaminant transport. The proposed framework will build on existing frameworks that operate at smaller scales e.g. the farm dairy effluent risk framework. This framework will be supported by a national scale "source-delivery-attenuation" analysis that will identify the gaps in the state of our current knowledge (with existing models) and measured stream loads. We will also investigate the use of "indirect" methods, such as hydrograph and pollutograph analysis, and tracers, to verify contaminant pathways. Such analyses will support development of the framework and allow us to extrapolate to areas where little base-line data are available. With appropriate knowledge, productive enterprises will have the opportunity to adapt and tailor their land use and management practices to work within the natural and built attenuation capacities of their landscape
Nutrients’ interactions with biochar’s surface chemistry
No full textSoil nutrients (NO3- and NH4+) are essential for crop growth. However, the presence of excess nutrients poses a significant environmental threat. Pyrogenic carbon materials, such as biochar, have gained attention in recent studies as fertilizer aids which can potentially mitigate nutrients from agricultural runoffs. Understanding interactions of NO3- and NH4+ with biochar’s surface chemistry is critical in evaluating effectiveness of biochar in mitigating risks of nutrient leaching. Surface chemical properties of biochar such as surface functional groups, pH, and elemental and mineral composition have been found to influence NO3- and NH4+ chemisorption mechanisms. The paper summarises the pertinent literature in this domain.https://www.massey.ac.nz/~flrc/workshops/17/Programme_Final_2017.pd
Integrating value chains to reward sustainable land use practices
No full textAn unusual feature of the New Zealand economy compared to other developed countries is that it has a relatively low ratio of exports to gross domestic product, but the percentage of merchandise exports devoted to agri-food products is very high (Dalziel et al, 2017). Indeed, the country’s primary production is focused on exports. This is shown in Figure 1, which depicts the share of final sales that is exported for the major agri-food industries in New Zealand; with two exceptions, the share is more than 70 per cent, rising to 90 per cent for dairy products. Consequently, global agri-food value chains are very important for New Zealand’s economic wellbeing
Using monthly stream water quality data to quantify nitrate transfer pathways in three Waikato catchments
No full textMonthly water quality sampling at the catchment outlet is carried out at many sites across New Zealand for state of the environment monitoring. This data is used for trend analysis, but little else. We have been exploring approaches for using this data in conjunction with concurrent stream flow data to identify and quantify the principal nutrient transfer pathways within catchments. In particular, monthly data may provide sufficient information for an inverse modelling approach.
Three contrasting mesoscale catchments were chosen for this study: (1) the Tahunaatara Stream (208 km²) in the Upper Waikato subregion, (2) the Puniu River (519 km²) in the Waipa subregion, and (3) the Mangatangi River (195 km²) in the Lower Waikato subregion. By considering four years of monthly water quality data from these catchments, alongside daily rainfall, potential evapotranspiration, and stream flow measurements, we were able to use the daily time step, spatially lumped catchment model “StreamGEM” with the Markov Chain Monte Carlo algorithm “DREAMZS” to predict daily stream flow and nitrate fluxes arriving at the catchment outlet via near-surface (NS), shallow fast seasonal groundwater (F), and deep slow older groundwater (S) flow paths, as well as to estimate the reliability/uncertainty of these predictions.
Despite high uncertainty in some model parameters, the flow and nitrate calibration data was well reproduced across all catchments (Nash-Sutcliffe model efficiency in the range 0.70–0.83 for daily flow, and 0.17–0.88 for nitrate concentration, both on log scale). Proportions of flow attributed to near-surface, fast seasonal groundwater and slow older groundwater were well defined, and consistent with expectations based on catchment geology. Fast groundwater contributed the bulk of the annual average nitrate yield in all of these catchments (range 31–97%), although contributions from slow groundwater were also high at Tahunaatara (range 18–63%), while contributions from near-surface flow were high at Mangatangi (range 24–63%).
This research highlights the potential of process based, spatially lumped modelling with commonly available monthly stream sample data, to elucidate high resolution catchment function, when appropriate calibration methods are used that correctly handle the inherent uncertainties
Next generation systems; A framework for prioritising innovation
No full textPrimary production industries are constantly changing in response to external factors such as new market opportunities, consumer demands, changing community expectations of the social and environmental outcomes associated with the primary sector, and technological innovation (Gerber et al., 2010). These external forces for change will likely intensify over the next 10 years (MfE, 2016; DairyNZ, 2016; NZHEA, 2016).
To enable primary producers to meet government targets such as doubling the value of New Zealand export returns while improving environmental performance, next generation land-based primary production systems (NGS) will be required. Next-generation systems may include redevelopment or redesign of existing enterprises and production systems, wholly new or novel enterprises, and new technologies that add options across temporal and spatial scales. The systems may cover a broad range of pastoral, arable, horticultural and forestry industries
Correction to: Chamoun et al., Bacterial pathogenesis and interleukin-17: interconnecting mechanisms of immune regulation, host genetics, and microbial virulence that influence severity of infection
No full textChamoun MN, Blumenthal A, Sullivan MJ, Schembri MA, Ulett GC. 2018. Bacterial pathogenesis and interleukin-17: interconnecting mechanisms of immune regulation, host genetics, and microbial virulence that influence severity of infection. Critical Reviews in Microbiology. https://doi.org/10.1080/1040841X.2018.1426556.
When the above article was first published online, the below three corrections were missed.
The author ‘Antje Blumenthal’ was wrongly affiliated to the affiliation “cSchool of Chemistry and Molecular Biosciences, and Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia”. Now this affiliation has been removed for this author.
The affiliation ‘bTranslational Research Institute, The University of Queensland Diamantina Institute, Woolloongabba, Australia’ of the author ‘Antje Blumenthal’ should read ‘bThe University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Australia’.
In Table 3, the sentence ‘Benefit of manipulating IL-17 levels to improve immunization strategies M. tuberculosis’ should read “Benefit of manipulating IL-17 levels to improve immunization strategies against M. tuberculosis”.No Full Tex
Generation of 22-mJ, 2.0-ps Pulses from a 1-kHz Ho:YLF Regenerative Chirped Pulse Amplifier
No full textWe report a CW-pumped Ho:YLF regenerative amplifier (RA) delivering pulses with 22.5-mJ energy and 2.0-ps duration at 1 kHz. The RA emitting at 2051 nm is broadband-seeded and implemented in a chirped pulse amplification system. © 2024 The Author(s
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