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30 results on '"Atkinson, Nicola"'

3. Hierarchical Disk Galaxy Assembly as the Origin of Scatter in the z~1 Stellar Mass Tully-Fisher Relation

Author

Atkinson, Nicola, Conselice, Christopher J., and Fox, Nicole

Subjects
Astrophysics
Abstract

Recent observations of distant disk galaxies show that there is little to no evolution in the relation between maximum rotation speed and stellar mass at z < 1.2. There is however a significant scatter between these two quantities whose origin is uncertain. We show in this paper that this scatter is at least partially the result of galaxy merging, revealing that disk galaxy growth at z < 1 is fundamentally hierarchical. We carry this out by calculating CAS (concentration, asymmetry, clumpiness) structural parameters using archival Hubble Space Telescope imaging of 91 high-redshift disk galaxies at 0.4 < z < 1.0 with robustly measured stellar masses and rotational maximum velocities taken from Conselice et al. (2005). We separate our sample into two redshift bins divided at z = 0.7, and investigate deviations from the stellar-mass Tully-Fisher relation in both the M_* and V_max directions, and how these correlate with structural asymmetries. We find a significant (> 3 sigma) correlation between the residuals from the stellar-mass Tully-Fisher relation in both the M_* and V_max directions, and high asymmetries. This result holds after we remove contributions from star formation and edge-on galaxies which can produce higher asymmetries unrelated to merging. While there are a few cases in which our disk galaxies have very large asymmetries, and are potentially involved in major mergers, in general these asymmetries are smaller than the major merger limit. It is therefore likely that these galaxies are forming hierarchically through minor galaxy mergers, which is also suggested by the constant slope and zero point of the stellar mass Tully-Fisher relation during the same epoch., Comment: 12 pages, MNRAS, submitted

Published
2007

4. Plant molecular response to combined drought and nematode stress

Author

Atkinson, Nicola Jane and Urwin, P. E.

Subjects
571.217
Abstract

Plants are adapted to respond to precise environmental stress conditions, activating specific molecular and physiological changes in order to minimise damage. Response to multiple stresses is therefore different to that to individual stresses. Simultaneous biotic and abiotic stress conditions are of particular interest, as the molecular signalling pathways controlling each interact and antagonise one another. Understanding such processes is crucial for developing broad-spectrum stress-tolerant crops. This study characterised the molecular response of plants to the concurrent stresses of drought (abiotic stress) and infection with plant-parasitic nematodes (biotic stress). Drought stress increased susceptibility to infection with Heterodera schachtii in Arabidopsis thaliana. The whole-genome transcriptome response to these stresses was analysed using microarrays. Each stress induced a particular subset of differentially expressed genes. A novel programme of gene expression was activated specifically in response to a combination of drought and nematode stress, involving 2394 differentially regulated genes. A diverse range of processes was found to be important in the response to multiple stresses, including plant hormone signalling, activation of transcription factors, cell wall modification, production of secondary metabolites, amino acid metabolism and pathogen defence signalling. Ten multiple stress-induced candidate genes were selected and their functions investigated using over-expression lines and loss-of-function mutants. Altered susceptibility to drought stress (TCP9, AZI1, RALFL8) and nematode infection (TCP9, RALFL8, ATMGL, AZI1) was observed in several of these lines. The effect of combined drought and nematode infection on nutritional parameters of tomato fruits was analysed. Drought stress lengthened flowering time and negatively affected carotenoid accumulation. Infection with Meloidogyne incognita reduced yield and ripening time and had a positive effect on the accumulation of phenolic compounds. The stresses in combination increased fruit sugar content. This work comprises the first whole-genome transcriptome study into combined abiotic and biotic stress. The results highlight the importance of studying stress factors in combination.

Published
2011

10. Understanding differences in access to water fountains and sugar-sweetened beverages in childrenʼs environments: A pilot study in high and low deprivation neighbourhoods

Author

Pearson, Amber L., de Latour, Phillip, Kemp, Gabrielle, Findlay, Nohoana, Halim, Angela, Atkinson, Nicola, Chong, Mark, Cameron, Rose, Brown, Courtney, Kim, Grace, Campbell, Paul, Hills, Toby, Jayawant, Aditya, Chae, Matthew, Bhagavan, Chiranth, French, Claire, Jenkin, Gabrielle, Smith, Moira, and Signal, Louise

Published
2014
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13. Intellectual property and environmental protection.

Author

Atkinson, Nicola and Sherman, Brad

Subjects
Intellectual property -- Environmental aspects, Environmental law -- Interpretation and construction, United Kingdom. Environmental Protection Act 1990
Published
1991

21. U-Pb zircon age constraints for the Ordovician Fishguard Volcanic Group and further evidence for the provenance of the Stonehenge bluestones.

Author

Bevins, Richard, Atkinson, Nicola, Ixer, Rob, and Evans, Jane

Subjects
*ORDOVICIAN Period, *ZIRCON, *LEAD, *BUILDING stones, *PETROLOGY, *GEOCHEMISTRY, *DEBITAGE (Stone implements)
Abstract

New U-Pb zircon ages from rhyolite samples of the Fishguard Volcanic Group, SW Wales, confirm a Middle Ordovician (Darriwilian) age for the group. One of the samples is from Craig Rhos-y-felin, which has recently been identified on petrological and geochemical grounds as the source of much of the debitage (struck flakes) at Stonehenge. Analysis of a Stonehenge rhyolite fragment yields an age comparable with that of the Craig Rhos-y-felin sample. Another Stonehenge fragment, thought to come from orthostat (standing stone) 48 and on petrographical grounds to be derived from the Fishguard Volcanic Group (but not Craig Rhos-y-felin), yields an age also consistent with a Fishguard Volcanic Group source. [ABSTRACT FROM AUTHOR]

Published
2017
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26. Longitudinal size distributions of bluegill bullies (Gobiomorphus hubbsi) and torrentfish (Cheimarrichthys fosteri) in two large New Zealand rivers.

Author

Atkinson, Nicola K. and Joy, Michael K.

Subjects
*BLUEGILL, *COMPETITION (Biology), *DISTRIBUTION (Probability theory), *REGRESSION analysis, *SIZE of fishes, *FRESHWATER fishes, *RIVERS
Abstract

The article presents a study which examines the longitudinal distribution of torrentfish (Cheimarrichthys fosteri) and bluegill bully (Gobiomorphus hubbsi). The study aims to establish any variation within and between longitudinal size distributions of both species. New Zealand Rivers were the locations of the study, one in Hutt River in Wellington, and another in Rakaia river in Canterbury. Quantile regression analysis has showed variation in migration rate within each specie.

Published
2009
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27. Response of Gobiomorphus hubbsi (bluegill bully) to odours of conspecific fish in the presence of natural stream odours: does habitat have an influence?

Author

Atkinson, Nicola K. and Joy, Michael K.

Subjects
*GOBIOMORPHUS, *GOBIIDAE, *AQUATIC habitats, *ODORS, *FISH odor, *BLUEGILL, *AQUATIC ecology, *LEPOMIS, *STREAM animals
Abstract

The article discusses the findings of the study related to the response of bluegill bullies or Gobiomorphus hubbsi to odours of conspecific fish in the presence of natural stream odours. It notes that the result was not consistent under naturally odoured water conditions, wherein no attraction towards conspecific odour occurred at low odour concentrations and only the weak avoidance of odour occurred at high concentrations. It further notes that the differences between natural and neutral water trials suggested the use of habitat odours over conspecific odours.

Published
2008
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30. Highly Efficient Gene Knockout in Medicago truncatula Genotype R108 Using CRISPR-Cas9 System and an Optimized Agrobacterium Transformation Method.

Author

Lawrenson T, Atkinson N, Forner M, and Harwood W

Subjects
CRISPR-Cas Systems genetics, Gene Knockout Techniques, Genotype, Agrobacterium genetics, Medicago truncatula genetics
Abstract

Medicago truncatula is the model plant species for studying symbioses with nitrogen-fixing rhizobia and arbuscular mycorrhizae, where edited mutants are invaluable for elucidating the contributions of known genes in these processes. Streptococcus pyogenes Cas9 (SpCas9)-based genome editing is a facile means of achieving loss of function, including where multiple gene knockouts are desired in a single generation. We describe how the user can customize our vector to target single or multiple genes, then how the vector is used to make M. truncatula transgenic plants containing target site mutations. Finally, obtaining transgene-free homozygous mutants is covered., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Published
2023
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