Hydroclimatic changes during the 8.2 ka event inferred from Irish subfossil pines

A significant cold event, derived from the Greenland ice cores, took place between 8200 and 8000 cal. BP. Modeling of the event suggests that higher northern latitudes would have experienced considerable decreases in precipitation and that Ireland would have witnessed one of the greatest depressions. However, no well-dated proxy record exists from the British Isles to test the model results. Here we present independent evidence for a phase of major pine recruitment on Irish bogs at around 8150 cal. BP. Dendrochronological dating of subfossil trees from three sites reveal synchronicity in germination across the region, indicative of a regional forcing, and allows for high-precision radiocarbon based dates. The inner-rings of 40% of all samples from the north of Ireland dating to the period 8,500-7,500 cal. BP fall within a 25-year window. The concurrent colonization of pine on peatland is interpreted as drier conditions in the region and provide the first substantive proxy data in support of a significant hydrological change in the north of Ireland accompanying the 8.2 ka event. Our results also indicate that the apparent temporal asynchrony between anomalies in proxy records at the time could be a result of differences in dating methods.

Hydroclimatic changes during the 8.2 ka event revealed by Irish pines

A pivotal cold event, deduced from the Greenland ice cores, took place between 8200 and 8000 cal. BP. Modelling of this climatic episode suggests that higher northern latitudes would have also experienced substantial reduction in rainfall and that Ireland would have observed a notable decline. No well-dated proxy record exists from the British Isles to test the model results. We present significant independent data for a phase of increased Scots pine initiation on Irish bogs at around 8150 cal. BP. Dendrochronological dating of sub-fossil Scots pine trees from three locations reveals synchronicity in germination across the area, indicative of a regional forcing, and allows for high-precision radiocarbon based dates. The starting rings of 40% of all samples from the north of Ireland dating to the period 8500-7500 cal. BP fall within a period of 25 years. The present colonisation model of Scots pine on peatland is interpreted as increasing drier conditions in the region and provides the first meaningful proxy data in support of a significant hydrological change in the north of Ireland accompanying the 8.2 ka event. The dating uncertainties associated with the Irish Scots pine record and the Greenland Ice Core Chronology 2005 (GICC05) do not allow for any overlap between the two. The results indicate that the discrepancy could be a result of dating inaccuracy that could have affected analysis of prior proxy alignments.

The Well-Aligned Orbit of Wasp-84b: Evidence for Disk Migration of a Hot Jupiter

We report the sky-projected orbital obliquity (spin–orbit angle) of WASP-84 b, a 0.69MJup planet in an 8.52 day orbit around a G9V/K0V star, to be λ = −0.3 ± 1.7°. We obtain a true obliquity of ψ = 17.3 ± 7.7° from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularized from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disk. This would make it the first “hot Jupiter” (P d < 10 ) to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (Teff < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets.

Mitochondrial DNA Damage Following Isolated Muscle Exercise: A Preliminary Investigation Into HO-1 Gene Expression

PURPOSE: This preliminary investigation was designed to test the hypothesis that high intensity single-leg exercise can cause extensive cell DNA damage, which subsequently may affect the expression of the HO-1 gene. METHODS: Six (n=6) apparently healthy male participants (age 27 + 7 yrs, stature 174 + 12 cm, body mass 79 + 4 kg and BMI 24 + 4 kg/m2) completed 100 isolated and continuous maximal concentric contractions (minimum force = 200 N, speed of contraction = 60°/sec) of the rectus femoris muscle. Using a spring-loaded and reusable Magnum biopsy gun with a 16-gauge core disposable biopsy needle, skeletal muscle micro biopsy tissue samples were extracted at rest and following exercise. mRNA gene expression was determined via two-step quantitative real-time PCR using GAPDH as a reference gene. RESULTS: The average muscle force production was 379 + 179 N. High intensity exercise increased mitochondrial 8-OHdG concentration (P < 0.05 vs. rest) with a concomitant decrease in total antioxidant capacity (P < 0.05 vs. rest). Exercise also increased protein oxidation as quantified by protein carbonyl concentration (P < 0.05 vs. rest). HO-1 expression increased (> 2-fold change vs. rest) following exercise, and it is postulated that this change was not significant due to low subject numbers (P > 0.05). CONCLUSION: These preliminary findings tentatively suggest that maximal concentric muscle contractions can cause intracellular DNA damage with no apparent disruption to the expression of the antioxidant stress protein HO-1. Moreover, it is likely that cell oxidant stress is required to activate the signal transduction cascade related to the expression of HO-1. A large-scale study incorporating a greater subject number is warranted to fully elucidate this relationship.

Asynchrony in key Holocene chronologies: Evidence from Irish bog pines

The Greenland Ice Core Chronology 2005 (GICC05) and the radiocarbon calibration curve (IntCal) are the foremost time scales used in paleoclimatic and paleoenvironmental studies of the most recent 10 k.y. Due to varying and often insufficient dating resolution, opportunities to test the synchrony of these two influential chronologies are rare. Here we present evidence for a phase of major pine recruitment on Irish bogs at ca. 8160 yr B.P. Dendrochronological dating of subfossil trees from three sites reveals synchronicity in germination across the study area, indicative of a regional forcing. The concurrent colonization of pine on peatland is interpreted in terms of drier surface conditions and provides the first substantive proxy data in support of a significant hydroclimatic change in the north of Ireland accompanying the 8.2 ka climate cooling event. The date of pine establishment does not overlap with the GICC05 age range for the event, and possible lags between responses are unlikely to explain the full difference. In light of recent studies highlighting a possible offset in GICC05 and IntCal dates, the Irish pine record supports the notion of ice core dates being too early during the period of study. If the suggested discrepancy in timing is an artifact of chronological error, it is likely to have affected interpretations of previous proxy comparisons and alignments.

The Cyrenaican Prehistory Project 2011: Late-Holocene environments and human activity from a cave fill in Cyrenaica, Libya

Little is known about late Holocene environmental change in Cyrenaica. The late Holocene sequence in the Haua Fteah, the key regional site, is highly discontinuous and characterised by stable-burning deposits. The geoarchaeology of the late-Holocene cave fill of a small cave, CP1565, located close to the Haua Fteah, is described. The well-stratified sequence, dating from the fourth century AD to the present day, provides a glimpse of life at the bottom of the settlement hierarchy and of changing environments over the last 1600 years, with degraded vegetation and aridity in the ‘Little Ice Age’.

Old World megadroughts and pluvials during the Common Era

Climate model projections suggestwidespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era.
The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries
reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.

Routledge International Handbook of Rural Studies.:Understanding the association between rural ethnicity and inequalities

Rural areas are facing demographic transformation. Some localities have experienced significant levels of (internal and international) immigration in recent decades. In other rural places, a shifting minority: majority ratio (arising mainly from increased minority fertility and decreases in the majority population) is altering the rural landscape. It is this context of increasingly diverse rural societies that frames this chapter. It begins by examining inequalities arising from ethnicity in a rural context. The review proceeds by identifying how different factors, including recent patterns of international migration and historical legacies of ethnic diversity, intertwine to produce multi-cultural rural areas. First of all an overview of the significance of the ‘ethnic’ label is presented, recognizing its limitations and also its usefulness. Having established this context the chapter proceeds by highlighting the way in which rural ethnic inequalities are measured and also the particular challenges of measuring rural poverty. The processes that produce inequalities among ethnic groups are examined, with particular attention on migration and space and place, but mindful of historical legacies along with economic transformations and associated recent migration patterns. Finally, the conclusion of the chapter highlights gaps and identifies areas for future research agendas.

Extreme wet conditions coincident with Bronze Age abandonment of upland areas in Britain

Abandonment of farming systems on upland areas in southwest Britain during the Late Bronze Age – some 3000 years ago – is widely considered a ‘classic’ demonstration of the impact of deteriorating climate on the vulnerability of populations in such marginal environments. Here we test the hypothesis
that climate change drove the abandonment of upland areas by developing new chronologies for humanactivity on upland areas during the Bronze Age across southwest Britain (Dartmoor, Exmoor and Bodmin Moor). We find Bronze Age activity in these areas spanned 3900–2950 calendar years ago with abandonment by 2900 calendar years ago. Holocene Irish bog and lake oak tree populations provide evidence of major shifts in hydroclimate across western Britain and Ireland, coincident with ice rafted debris layers recognized in North Atlantic marine sediments, indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region. We observe abandonment of
upland areas in southwest Britain coinciding with a sustained period of extreme wet conditions that commenced 3100 calendar years ago. Our results are consistent with the view that climate change increased the vulnerability of these early farming communities and led to a less intensive use of such marginal environments across Britain.

Stable oxygen isotopes in irish oaks: potential for reconstructing local and regional climate

The long Irish oak tree-ring chronology, developed for archaeological dating and radiocarbon calibration, is the longest of any in northwest maritime Europe, spanning most of the Holocene (7,272 years). Unfortunately, the rings widths do not carry a strong climate signal and the record hasnever been satisfactorily applied for dendroclimatic reconstruction. This pilot study explores the potential for extracting a climate signal from Irish oaks by comparing the stable oxygen isotopes ratios from 10 oak tree cores (Quercus robur and Quercus petraea L.) collected across the Armagh region of NE Ireland with local and regional climatic and stable isotopic data. Statistically significant correlations between isotope ratios and the amount of summer precipitation (r = -0.44) point to the isotopic composition of summer rainfall as the dominant signal. Including the Armagh data into an extended regional oxygen isotope series did not reduce the correlation coefficient with regional precipitation (r = -0.68, p < 0.01). Correlations of this magnitude in dendro-hydroclimatology are typically restricted to trees growing at their ecological limits. This research suggests that there is considerable potential for including living trees and ancient timbers from Ireland into a regional composite to reconstruct the summer hydroclimate of Britain and Ireland.

The Ectocarpus genome and the independent evolution of multicellularity in brown algae

Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related(1). These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1). We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae(2-5), closely related to the kelps(6,7) (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic(2) approaches to explore these and other(4,5) aspects of brown algal biology further.