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  • 1
    Electronic Resource
    Electronic Resource
    Gastro-oesophageal reflux is more prevalent in Western dyspeptics: a prospective comparison of British and South-East Asian patients with dyspepsia (2005)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 21 (2005), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : There is a paucity of data directly comparing dyspepsia in Western and Eastern populations.Aim : To compare clinical symptoms, epidemiological factors and endoscopic diagnoses in two sample populations with dyspepsia from the United Kingdom and South-East Asia in a cross-sectional study.Methods : Patients with uncomplicated dyspepsia attending endoscopy units in Leeds, UK, and Kuala Lumpur, Malaysia, were prospectively interviewed and underwent subsequent endoscopy.Results : A total of 1003 Malaysian patients (January 2002 to August 2003) and 597 Caucasian British patients (January 2000 to October 2002) were studied. The mean age was 48.7 ± 15.8 and 47.5 ± 13.8 years for the Malaysian and British patients respectively (P = NS). There was a higher proportion of cigarette smoking (35.7% vs. 12.4%, P 〈 0.0001) and alcohol consumption (34.4% vs. 2.0%, P 〈 0.0001) amongst British patients, but no difference in non-steroidal anti-inflammatory drug use nor having Helicobacter pylori infection. Gastro-oesophageal reflux disease (GERD) symptoms were more common in British compared with South-East Asian patients [heartburn (72% vs. 41%), regurgitation (66% vs. 29.8%) and dysphagia (21.1% vs. 7.3%), P 〈 0.0001]. This correlated with an increased endoscopic finding of oesophagitis (26.8% vs. 5.8%) and columnar-lined oesophagus (4.4% vs. 0.9%) amongst British patients (P 〈 0.001). A logistic regression model revealed that British Caucasian race (OR 9.7; 95% CI = 5.0–18.8), male gender (OR 2.0; 95% CI = 1.4–2.9) and not having H. pylori infection (OR 0.5; 95% CI = 0.3–0.7) were independent predictors for oesophagitis.Conclusion : GERD is more common in British compared with South-East Asian dyspeptic patients suggesting that race and/or western lifestyle are important risk factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.2005.02455.x
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A highly sensitive nuclear recoil detector based on superfluid3He-B (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 9-16 
    Details
    ISSN: 1573-7357
    Keywords: 29.40.Ym 67.57.Bc 95.55.Vj 95.35.+d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The excitations in superfluid3He have a dispersion curve in which the energy minimum does not coincide with the momentum minimum. As a result, when a mechanical resonator moves through a gas of such excitations, normal and Andreev scattering processes introduce a large asymmetry into the momentum exchange and the mechanical resonator experiences a very large drag force. A gas of such excitations is thus very easy to detect even at very low densities. We have exploited this effect to monitor the increase in excitation density in a small volume caused by a particle interaction. The working volume is filled with superfluid3He-B at around 100 μK. A particle undergoing an interaction in the volume releases a shower of quasiparticle excitations which can be detected by the increase in damping on a vibrating wire resonator. A small hole in the container allows the excitations to leak out into the outside colder liquid to reset the working liquid to the resting state. Using an existing experiment we can detect nuclear recoil interactions depositing energies as low as 500 eV. Two simple modifications should allow us to detect interactions in the 10 eV range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754556
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    Paper (German National Licenses)
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  • 3
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    When is a biogeochemical model too complex? Objective model reduction for North Atlantic time-series sites (2013)
    Elsevier
    In:  Progress in Oceanography, 116 . pp. 49-65.
    Details
    Publication Date: 2019-07-30
    Description: Highlights • We objectively identify and remove unconstrained parameters from a marine ecosystem model. • Optimal model complexity is identified using three model selection metrics. • As many as 14 of the model’s 30 parameters can be removed, with no significant reduction in model-data misfit. • Optimal model structures and parameters are different at two different North Atlantic locations. • The specialised structures and parameters at each site may be unsuitable for new environments The degree of structural complexity that should be incorporated in marine biogeochemical models is unclear. We know that the marine ecosystem is complex, and that its observed behaviour is attributable to the interaction of a large number of separate processes, but observations are scarce and often insufficient to constrain more than a small number of model parameters. This issue is addressed using a novel algorithm that systematically removes model processes that are not constrained by observations. The algorithm is applied to a one-dimensional, eight component ecosystem-biogeochemistry model at two North Atlantic time-series sites. Between 11 and 14 of the 30 model parameters can be removed at each site with no significant reduction in the model’s ability to fit upper ocean (0–200 m) biogeochemical tracer and productivity data. The statistically optimal model structures and parameters provide estimates of the most likely state variables and fluxes at each site. Differences in these estimates between the two sites indicate that the optimal models are specialised to both the physical environment and the assimilated observations. At each site the heavily reduced models may thus be suitable for diagnostic purposes but may not be sufficiently complex for more general applications, such as in global ocean general circulation models, or for predicting the response of marine systems to environmental change.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.pocean.2013.06.002
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Top-down control of marine phytoplankton diversity and ecosystem functioning in a global ecosystem model (2012)
    In:  [Poster] In: ClimECO3 Summer school, 23.-28.07.2012, Ankara, Turkey .
    Details
    Publication Date: 2018-12-14
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Poster
  • 5
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    Top-down control of biodiversity (2010)
    In:  [Poster] In: ClimECO2 summer school, 23.-27.08.2010, IUEM, Brest, France .
    Details
    Publication Date: 2012-07-06
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
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    OceanRep: Poster
  • 6
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    Top-down control of biodiversity (2010)
    In:  [Poster] In: Advanced School on Complexity, Adaptation and Emergence in Marine Ecosystems, ICTP, Miramare, 18.10.2010, Triest, Italy .
    Details
    Publication Date: 2012-07-06
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
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    OceanRep: Poster
  • 7
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    Effects of zooplankton feeding strategies on community structure in a simple plankton model (2010)
    In:  [Talk] In: Ocean Sciences Meeting 2010 "Plankton Grazing Rates in the Sea: So Many Methods, So Much Learned, So Much To Do", 22.02.-26.02.2010, Portland, Oregon, USA .
    Details
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 8
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    Marine phytoplankton diversity: top-down control and the diversity-productivity relationship (2011)
    In:  [Talk] In: 3. Advances in Marine Ecosystem Modelling Research Symposium (AMEMR III 'The Next Generation'), 27.-30.06.2011, Plymouth, UK .
    Details
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 9
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    Top-down control of marine phytoplankton diversity in a global ecosystem model (2012)
    Elsevier
    In:  Progress in Oceanography, 101 . pp. 1-13.
    Details
    Publication Date: 2020-10-16
    Description: The potential of marine ecosystems to adapt to ongoing environmental change is largely unknown, making prediction of consequences for nutrient and carbon cycles particularly challenging. Realizing that biodiversity might influence the adaptation potential, recent model approaches have identified bottom-up controls on patterns of phytoplankton diversity regulated by nutrient availability and seasonality. Top-down control of biodiversity, however, has not been considered in depth in such models. Here we demonstrate how zooplankton predation with prey-ratio based food preferences can enhance phytoplankton diversity in a ecosystem-circulation model with self-assembling community structure. Simulated diversity increases more than threefold under preferential grazing relative to standard density-dependent predation, and yields better agreement with observed distributions of phytoplankton diversity. The variable grazing pressure creates refuges for less competitive phytoplankton types, which reduces exclusion and improves the representation of seasonal phytoplankton succession during blooms. The type of grazing parameterization also has a significant impact on primary and net community production. Our results demonstrate how a simple parameterization of a zooplankton community response affects simulated phytoplankton community structure, diversity and dynamics, and motivates development of more detailed representations of top-down processes essential for investigating the role of diversity in marine ecosystems.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.pocean.2011.11.016
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Co-existence of distinct Ostreococcus ecotypes at an oceanic front (2017)
    ASLO (Association for the Sciences of Limnology and Oceanography)
    In:  Limnology and Oceanography, 62 (1). pp. 75-88.
    Details
    Publication Date: 2020-02-06
    Description: Western boundary currents support high primary production and carbon export. Here, we performed a survey of photosynthetic picoeukaryotes in the North Pacific Ocean in four transects crossing the Kuroshio Front. Prasinophyte algae comprised 85% of 18S rRNA gene sequences for photosynthetic taxa in the 〈5 μm size fraction. The picoplanktonic (〈2 μm) genera Micromonas and Ostreococcus comprised 30% and 51% of the total photosynthetic 18S rDNA sequences from five stations. Phylogenetic analysis showed that two Ostreococcus ecotypes, until now rarely found to co‐occur, were both present in the majority of samples. Ostreococcus ecotype OI reached 6,830 ± 343 gene copies mL−1, while Ostreococcus ecotype OII reached 50,190 ± 971 gene copies mL−1 based on qPCR analysis of the 18S rRNA gene. These values are higher than in studies of other oceanographic regions by a factor of 10 for OII. The data suggest that meso‐ and finer‐scale physical dynamics had a significant impact on the populations at the front, either by mingling ecotypes from different source regions at fine scales (∼10s km) or by stimulating their growth through vertical nutrient injections. We investigate this hypothesis with an idealized diffusion‐reaction model, and find that only a combination of mixing and positive net growth can explain the observed distributions and overlap of the two Ostreococcus ecotypes. Our field observations support larger‐scale numerical ocean simulations that predict enhanced biodiversity at western boundary current fronts, and suggest a strategy for systematically testing that hypothesis.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/lno.10373
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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