Annually resolved North Atlantic marine climate over the last millennium

This is the final version of the article. Available from Nature Publishing Group via the DOI in this record.Owing to the lack of absolutely dated oceanographic information before the modern instrumental period, there is currently significant debate as to the role played by North Atlantic Ocean dynamics in previous climate transitions (for example, Medieval Climate Anomaly-Little Ice Age, MCA-LIA). Here we present analyses of a millennial-length, annually resolved and absolutely dated marine δ(18)O archive. We interpret our record of oxygen isotope ratios from the shells of the long-lived marine bivalve Arctica islandica (δ(18)O-shell), from the North Icelandic shelf, in relation to seawater density variability and demonstrate that solar and volcanic forcing coupled with ocean circulation dynamics are key drivers of climate variability over the last millennium. During the pre-industrial period (AD 1000-1800) variability in the sub-polar North Atlantic leads changes in Northern Hemisphere surface air temperatures at multi-decadal timescales, indicating that North Atlantic Ocean dynamics played an active role in modulating the response of the atmosphere to solar and volcanic forcing.We thank the members of the RV Bjarni Sæmundsson (Cruise No. B05-2006). This work was supported by the NERC-funded ULTRA project (Grant Number NE/H023356/1), NERC-funded CLAM project; (Project No. NE/N001176/1) and EU Millennium Project (Project number 017008). This study is a contribution to the Climate Change Consortium for Wales (C3W). We thank Brian Long (Bangor University) and Dr Julia Becker (Cardiff University) for their technical support, and Dr Manfred Mudelsee for his assistance with the trend analysis. We thank Dr Jessica Tierney and an anonymous reviewer for providing the constructive comments in the reviewing process

Auditory Spatial Acuity Approximates the Resolving Power of Space-Specific Neurons

The relationship between neuronal acuity and behavioral performance was assessed in the barn owl (Tyto alba), a nocturnal raptor renowned for its ability to localize sounds and for the topographic representation of auditory space found in the midbrain. We measured discrimination of sound-source separation using a newly developed procedure involving the habituation and recovery of the pupillary dilation response. The smallest discriminable change of source location was found to be about two times finer in azimuth than in elevation. Recordings from neurons in its midbrain space map revealed that their spatial tuning, like the spatial discrimination behavior, was also better in azimuth than in elevation by a factor of about two. Because the PDR behavioral assay is mediated by the same circuitry whether discrimination is assessed in azimuth or in elevation, this difference in vertical and horizontal acuity is likely to reflect a true difference in sensory resolution, without additional confounding effects of differences in motor performance in the two dimensions. Our results, therefore, are consistent with the hypothesis that the acuity of the midbrain space map determines auditory spatial discrimination

Prevalence of Peripheral Artery Disease is Higher in Persons Living with HIV Compared to Uninfected Controls

OBJECTIVE: Ankle-brachial index (ABI) is an excellent tool for diagnosing peripheral artery disease (PAD). We aimed to determine the prevalence and risk factors for PAD in people living with HIV (PLWH) compared to uninfected controls. We hypothesized that prevalence of PAD would be higher among PLWH than among controls independent of traditional cardiovascular disease (CVD) risk factors. METHODS: PLWH aged ≥40 were recruited from the Copenhagen comorbidity in HIV infection (COCOMO) study. Sex and age matched uninfected controls were recruited from the Copenhagen General Population Study. We defined PAD as ankle-brachial index (ABI) ≤ 0.9 and assessed risk factors for PAD using logistic regression adjusting for age, sex, smoking status, dyslipidemia, diabetes, hypertension and hsCRP. RESULTS: Among 908 PLWH and 11,106 controls, PAD was detected in 112 (12% CI [95% 10-14]) and 623 (6% [95% 5-6]), respectively (p<0.001); odds ratio (OR)=2.4 [95% 1.9-2.9], adjusted OR=1.7 [95% 1.3-2.3, p<.001]. Traditional CVD risk factors, but not HIV-related variables were associated with PAD. The strength of the association between PAD and HIV tended to be higher with older age (p=0.052, adjusted test for interaction). CONCLUSION: Prevalence of PAD is higher among PLWH compared to uninfected controls, especially among older persons, and remains so after adjusting for traditional CVD risk factors. Our findings expand the evidence base that PLWH have excess arterial disease to also include PAD. The exact biological mechanisms causing this excess risk remain to be elucidated. Until then, focus on management of modifiable traditional risk factors is important

Evidence for solar cycles in a late Holocene speleothem record from Dongge Cave, China

The association between solar activity and Asian monsoon (AM) remains unclear. Here we evaluate the possible connection between them based on a precisely-dated, high-resolution speleothem oxygen isotope record from Dongge Cave, southwest China during the past 4.2 thousand years (ka). Without being adjusted chronologically to the solar signal, our record shows a distinct peak-to-peak correlation with cosmogenic nuclide 14C, total solar irradiance (TSI) and sunspot number (SN) at multi-decadal to centennial timescales. Further cross-wavelet analyses between our calcite δ18O and atmospheric 14C show statistically strong coherence at three typical periodicities of ~80, 200 and 340 years, suggesting important roles of solar activities in modulating AM changes at those timescales. Our result has further indicated a better correlation between our calcite δ18O record and atmospheric 14C than between our record and TSI. This better correlation may imply that the Sun–monsoon connection is dominated most likely by cosmic rays and oceanic circulation (both associated to atmospheric 14C), instead of the direct solar heating (TSI)

Floral advertisement scent in a changing plant-pollinators market

Plant-pollinator systems may be considered as biological markets in which pollinators choose between different flowers that advertise their nectar/pollen rewards. Although expected to play a major role in structuring plant-pollinator interactions, community-wide patterns of flower scent signals remain largely unexplored. Here we show for the first time that scent advertisement is higher in plant species that bloom early in the flowering period when pollinators are scarce relative to flowers than in species blooming later in the season when there is a surplus of pollinators relative to flowers. We also show that less abundant flowering species that may compete with dominant species for pollinator visitation early in the flowering period emit much higher proportions of the generalist attractant β-ocimene. Overall, we provide a first community-wide description of the key role of seasonal dynamics of plant-specific flower scent emissions, and reveal the coexistence of contrasting plant signaling strategies in a plant-pollinator market

Long-lasting alterations in adipose tissue density and adiponectin production in people living with HIV after thymidine analogues exposure

BACKGROUND: Thymidine analogues (TA) and didanosine (ddI) are associated with long-lasting adipose tissue redistribution. Adiponectin is a widely used marker of adipocyte activity, and adipose tissue density assessed by CT-scan is associated with adipocyte size and function. We hypothesized that prior exposure to TA and ddI was associated with long-lasting adipose tissue dysfunction in people living with HIV (PLWH). Thus, we tested possible associations between markers of adipose tissue dysfunction (adipose tissue density and adiponectin) and prior exposure to TA and/or ddI, years after treatment discontinuation. METHODS: Eight hundred forty-eight PLWH from the COCOMO study were included and stratified according to prior exposure to TA and/or ddI (with, n = 451; without n = 397). Visceral (VAT) and subcutaneous (SAT) adipose tissue area and density were determined by single slice abdominal CT-scan at lumbar 4th level. Venous blood was collected and analyzed for adiponectin. Multivariable linear and logistic regression analyses were used to test our hypotheses. Multivariable models were adjusted for age, sex, smoking, origin, physical activity, BMI, and adipose tissue area (VAT or SAT area, accordingly to the outcome). RESULTS: prior exposure to TA and/or ddI was associated with excess risk of low VAT (adjusted OR (aOR) 1.74 [1.14; 2.67]) and SAT density (aOR 1.74 [1.18; 2.58]), for a given VAT and SAT area, respectively. No association between VAT and SAT density with time since TA and/or ddI discontinuation was found. 10 HU increase in VAT density was associated with higher adiponectin plasma level and this association was not modified by prior exposure to TA and/or ddI. Prior exposure to TA and/or ddI was associated with 9% lower [- 17;-2] plasma adiponectin levels and with excess risk of low adiponectin (aOR 1.74 [1.10; 2.76]). CONCLUSIONS: We described low adipose tissue density and impaired adiponectin production to be associated with prior exposure to TA and/or ddI even years after treatment discontinuation and independently of adipose tissue area. These findings suggest that prior TA and ddI exposure may have long-lasting detrimental effects on adipose tissue function and, consequently, on cardiometabolic health in PLWH