Applicability of the Long Chain Diol Index (LDI) as a Sea Surface Temperature Proxy in the Arabian Sea

The long-chain diol index (LDI) is a relatively new proxy for sea surface temperature (SST) which has been rarely applied in upwelling regions. Here, we evaluated its application by comparison with other SST records obtained by commonly used proxies, that is, the Mg/Ca ratio of the planktonic foraminifera species Globigerinoides ruber and the alkenone paleothermometer U-37(K '). We focused on the last glacial-interglacial transition of four different sedimentary archives from the western and northern Arabian Sea, which are currently under the influence of monsoon-induced upwelling and the associated development of an oxygen minimum zone. The UK ' 37 ${{\mathrm{U}}{\mathrm{K}\prime }}_{37}$ and Mg/Ca-G.ruber SST records revealed an increase of 0.6-3.4 degrees C from the Last Glacial Maximum to the late Holocene with somewhat higher amplitude in the northern part of the Arabian Sea than compared to the western part. In contrast, the LDI SSTs did not reveal major changes during the last glacial-interglacial transition which was followed by a decreasing trend during the Holocene. The LGM versus the Holocene LDI SSTs ranged between -0.2 and -2.7 degrees C. Particularly at one record, offshore Oman, the SST decrease during the Holocene was high in amplitude, suggesting a potential cold bias, possibly related to changes in upwelling intensity. This indicates that care has to be taken when applying the LDI for annual mean SST reconstruction in upwelling regions

Hydrogen isotopic ratios of long-chain diols reflect salinity

Long-chain diols (LCDs) are ubiquitous lipids produced by freshwater and marine algae. A combination of semi-preparative high performance liquid chromatography and gas chromatography isotope ratio monitoring mass spectrometry, allowed the measurement of δ2H of individual LCDs from cultures, which indicated a correlation with the hydrogen isotope composition of the growth water and a species-specific effect. Results from environmental samples along a salinity gradient indicated the potential of δ2H ratios of LCDs to trace the hydrogen isotopic composition of water and sea surface salinity.ISSN:0146-638

Earthworm management in tropical agroecosystems

Ecological and demographic parameters of 26 species of native and exotic earthworms species common in tropical agroecosystems, with large environmental tolerance and/or extended distribution were investigated. Principal component analysis (PCA) isolated four groups : (i) large native endogeic and anecic species (16-32 g individual fresh wt) with long generation time (2-4 years), low fecundity (0.5-3.1 cocoons/year/adult) and one hatchling per cocoon ; (ii) medium size species (1.2-6 g) endogeic mesohumic, with intermediate fecundity (1.3-45 cocoons/year/adult) ; (iii) small species (0.17-1.25 g f.w.) mainly endogeic polyhumic, with short generation time (3-7 months), intermediate fecundity (10-68 cocoons/year/adult) and one hatchling per cocoon ; and (iv) generally small (80-150 mg f.w.) species mainly exotic and epigeic, with short generation time (1-3 months), very high fecundity (50-350 cocoons/year/adult) and up to three hatchlings per cocoon. Casts may be either large globular or small granular. The selective investigations of large organic particles and small mineral particles (clays) concentrates total organic matter in the casts. There is an intense mineralization rate of nitrogen in the casts (6-29% of organic N), exotic worms seeming to be less efficient than natives at mineralizing N. The mineral phosphorus content of casts is always at least 30% higher than in the non-ingested soil. All these worms ingest daily, on average, three times their own weight of soil at the adult stage (1-9) and much more when juvenile ; up to 1000 Mg dry soil/ha may transit yearly through earthworm guts. (Résumé d'auteur

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum