1,721,398 research outputs found
Creighton Law Review
No full textINTRODUCTION|The Employee Retirement Income Security Act, as amended ("ERISA"), was enacted in 1974. The primary purpose and special nature of ERISA is to secure the protection of private individual pension rights and retirement viability of participants. In the second quarter of fiscal year 2015, between April and June 30, private and public pension net assets totaled $390. billion. Recently, ERISA litigation has burgeoned and the United States Supreme Court has acknowledged the importance of ERISA. The Supreme Court's decision in Fifth Third Bancorp v. Dudenhoeffer began to shed light on the shifting burden of proof in ERISA litigation. However, the Supreme Court has refrained from entering into the litigation landscape post Dudenhoeffer, rendering the landscape unclear as to who bears the burden of proof in ERISA fiduciary breach litigation proceedings...222015-2016437-466494
Reconstructing Holocene climate change in Scotland utilising peat stratigraphy and tephrochronology
No full textIn 2 vols.Available from British Library Document Supply Centre-DSC:DX206534 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Summer temperature gradients in northwest Europe during the Lateglacial to early Holocene transition (15-8 ka BP) inferred from chironomid assemblages
Full text linkThe raster temperature data was interpolated from site temperature data estimated from Chironomid records using Kriging. Temperatures are in Degrees Centigrage. The dataset covers all of Northern Europe including Iceland and Scandanavia.</span
Critical transitions in ecosystem state may be driven by coupled feedback mechanisms: a case study from Erhai lake, China
No full textCritical transitions between ecosystem states can be triggered by relatively small external forces or internal perturbations and may show time-lagged or hysteretic recovery. Understanding the precise mechanisms of a transition is important for ecosystem management, but it is hampered by a lack of information about the preceding interactions and associated feedback between different components in an ecosystem. This paper employs a range of data, including paleolimnological, environmental monitoring and documentary sources from lake Erhai and its catchment, to investigate the ecosystem structure and dynamics across multiple trophic levels through the process of eutrophication. A long-term perspective shows the growth and decline of two distinct, but coupled, positive feedback loops: a macrophyte-loop and a phosphorus-recycling-loop. The macrophyte-loop becameweaker, and the phosphorus-recycling-loop became stronger during the process of lake eutrophication, indicating that the critical transition was propelled by the interaction of two positive feedback loops with different strengths. For lake restoration, future weakening of the phosphorus-recycling loop or a reduction in external pressures is expected to trigger macrophyte growth and eventuallyproduce clear water conditions, but the speed of recovery will probably depend on the rates of feedback loops and the strength of their coupling
Summer temperature gradients in northwest Europe during the Lateglacial to early Holocene transition (15–8 ka BP) inferred from chironomid assemblages
No full textWe present a series of summer air temperature isotherm maps based on chironomid-inferred temperatures from northwest Europe, covering the Lateglacial and early Holocene (15–8 ka BP). These maps are the first of their kind, and use data derived from 22 Lateglacial sites and 34 early Holocene sites. The isotherms are generated by weighted spatial interpolation (kriging). The major patterns of chironomid-inferred summer temperatures are spatially well-resolved in both the Lateglacial and early Holocene. The isotherm maps indicate that there was a strong west to east gradient during the Lateglacial Interstadial (GI-1) due to the influence of thermohaline circulation in the regions bordering the north Atlantic, which diminishes eastwards. A strong north to south temperature gradient is also apparent, particularly in eastern regions, influenced by the extent of the Scandinavian ice-cap. Peak temperatures are achieved early in the Interstadial in the south of the region but occur towards the end of the Interstadial in the north. Holocene warming varies spatially and temporally and is earliest in the south and east, but later in the north and west. During the period covered in our study maximum warmth is reached ca. 10 ka BP. The chironomid-based Lateglacial isotherm maps are compared with previously published isotherm maps from the same region based on beetle-inferred temperatures. While the trends shown in the two datasets are similar, beetle-inferred temperatures are often warmer than chironomid-inferred temperatures. This is especially marked in GI-1e and may be due to microclimatic effects causing the chironomids to underestimate air temperatures and/or the beetles to over-estimate air temperatures. The spatial coherence between sites in both the Lateglacial and early Holocene suggest that the chironomid-based temperature estimates are largely reliable, although data testing suggests that estimates from southern Scandinavia may be less reliable perhaps due to high topographical relief influencing local climate. More data points are required, particularly from northwest Scotland, southwest England and Wales, northeast France, Denmark, Finland and the Baltic States, to confirm trends and provide even coverage and a denser network of site
A 3000-year multiproxy palaeoclimate record from Killorn Moss, Stirlingshire, Scotland
Full text linkPeatlands across the United Kingdom and Europe represent an important source of palaeoenvironmental and palaeoclimatological data for the Holocene time period. Here we derive a detailed 3000-year record of inferred changes in water table from the raised bog at Killorn Moss in central Scotland, employing a multiproxy approach. Proxies are compared and contrasted, and the merits of a multiproxy approach are highlighted. Ten changes to wetter conditions supported by at least two proxies are evident at Killorn, with substantial shifts related to the Sub-boreal/Sub-atlantic transition and post Roman and Dark Age deteriorations. Inferred changes in climate are compared with a local record from another raised bog and with more geographically widespread locations highlighting corresponding events, but also evidencing the importance of robust dating
Subfossil chironomid variability in surface sediment samples from Icelandic lakes: implications for the development and use of training sets
No full textA suite of surface sediment samples from
three Icelandic lakes was analysed for subfossil
chironomid head capsules, and a quantitative July
air temperature inference model was applied to the
data to investigate whether there was significant
variability among samples taken from a lake. Ordination
and simple regression methods were used to
analyse the relationships between environmental and
sedimentological variables and the chironomid
assemblages and inferred temperature data. Substrate
was the most important influence on the chironomid
assemblages and inferred temperatures, while water
depth at the sampling location had no relationship
with the chironomid-inferred temperatures. Withinlake
variability of the chironomid assemblages and
their inferred temperatures, however, were not significant
statistically, suggesting that in lakes of
western and northwest Iceland within-lake sampling
location has no effect on the data obtained, and
therefore on training set samples
Environmental controls on modern chironomid faunas from NW Iceland and implications for reconstructing climate change
No full textReconstructing climate change quantitatively over millennial timescales is crucial for understanding the processes that affect the climate system. One of the best methods for producing high resolution, low error, quantitative summer air temperature reconstructions is through chironomid analyses. We analysed over 50 lakes from NW and W Iceland covering a range of environmental gradients in order to test whether the distribution of the Icelandic chironomid fauna was driven by summer temperature, or whether other environmental factors were more dominant. A range of analyses showed the main environmental controls on chironomid communities to be substrate (identified through loss-on-ignition and carbon content) and mean July air temperature, although other factors such as lake depth and lake area were also important. The nature of the Icelandic landscape, with numerous volcanic centres (many of which are covered by ice caps) that produce large quantities of ash, means that relative lake carbon content and summer air temperature do not co-vary, as they often do in other chironomid datasets within the Arctic as well as more temperate environments. As the chironomid-environment relationships are thus different in Iceland compared to other chironomid training sets, we suggest that using an Icelandic model is most appropriate for reconstructing past environmental change from fossil Icelandic datasets. Analogue matching of Icelandic fossil chironomid datasets with the Icelandic training set and another European chironomid training set support this assertion. Analyses of a range of chironomid-inferred temperature transfer functions suggest the best to be a two component WA-PLS model with r2jack = 0.66 and RMSEP = 1.095 °C. Using this model, chironomid-inferred temperature reconstructions of early Holocene Icelandic sequences show the magnitude of temperature change compared to contemporary temperatures to be similar to other NW European chironomid sequences, suggesting that the predictive power of the model is good
High resolution scanning of South Pacific lake sediment: relative benefits offered by state-of-the-art micro-XRF and SEM systems
No full textA methodological evaluation for the efficient investigation of laminated core material collected from the South Pacific islands is presented that is expected to be of broad interest to the core scanning community. Efficient identification of laminae, their number, chemistry and mineralogy provide crucial information in inferring sediment accumulation rates and environmental and climate change. The material investigated was collected as part of NERC grant NE/N006674/1 - The legacy of cyclone Pam: a unique opportunity to build a long term record of cyclone activity in the western tropical Pacific (PIs David Sear, Pete Langdon and Ian Croudace). The project is part of a multi-party study involving the PIs, 3 PhD students and collaborating specialists. Analytical data obtained from measurements of a 10 cm section of resin impregnated lake sediment from Lake Te Roto (Atiu Island, Cook Islands) will be discussed. Investigation of the sediment block was made using Itrax, Bruker M4+ micro-XRF and Leo SEM systems. The benefits of using the different approaches are evaluated with the purpose of establishing a preferred approach that would be applied to detailed investigation of all or selected core material collected from two field campaigns. The analytical timeline including an efficiency budget (sample preparation, analysis) as well as the robustness and comparability of analytical outputs (textural, density and elemental variations) will be presented
Climate of the Little Ice Age and the past 2000 years in northeast Iceland inferred from chironomids and other lake sediment proxies
No full textA sedimentary record from lake Stora
Viðarvatn in northeast Iceland records environmental
changes over the past 2000 years. Downcore data
include chironomid (Diptera: Chironomidae) assemblage
data and total organic carbon, nitrogen, and
biogenic silica content. Sample scores from detrended
correspondence analysis (DCA) of chironomid
assemblage data are well correlated with measured
temperatures at Stykkisho´lmur over the 170 year
instrumental record, indicating that chironomid
assemblages at Stora Viðarvatn have responded sensitively
to past temperature changes. DCA scores
appear to be useful for quantitatively inferring past
temperatures at this site. In contrast, a quantitative
chironomid-temperature transfer function developed
for northwestern Iceland does a relatively poor job of
reconstructing temperature shifts, possibly due to the
lake’s large size and depth relative to the calibration
sites or to the limited resolution of the subfossil
taxonomy. The pre-instrumental climate history
inferred from chironomids and other paleolimnological
proxies is supported by prior inferences from
historical documents, glacier reconstructions, and
paleoceanographic studies. Much of the first millennium
AD was relatively warm, with temperatures
comparable to warm decades of the twentieth century.
Temperatures during parts of the tenth and eleventh
centuries AD may have been comparably warm.
Biogenic silica concentrations declined, carbon:nitrogen
ratios increased, and some chironomid taxa
disappeared from the lake between the thirteenth and
nineteenth centuries, recording the decline of temperatures
into the Little Ice Age, increasing soil erosion,
and declining lake productivity. All the proxy reconstructions
indicate that the most severe Little Ice Age
conditions occurred during the eighteenth and nineteenth
centuries, a period historically associated with
maximum sea-ice and glacier extent around Iceland
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