Characterisation of early Archaean chemical sediments by trace element signatures

Rare earth element (REE) plus yttrium (Y) patterns of modem seawater have characteristic features that can be used as chemical fingerprints. Reliable proxies for marine REE + Y chemistry have been demonstrated from a large geological time span, including Archaean banded iron formation (BIF), stromatolitic limestone, Phanerozoic reef carbonate and Holocene microbialite. Here we present new REE + Y data for two distinct suites of early Archaean (ca. 3.7-3.8 Ga) metamorphosed rocks from southern West Greenland, whose interrelationships, if any, have been much debated in recent literature. The first suite comprises mangetite-quartz BIF, magnetite-carbonate BIF and banded magnetite-rich quartz rock, mostly from the Isua Greenstone Belt (IGB). The REE + Y patterns, particularly diagnostic anomalies (Ce/Ce*, Pr/Pr*), are closely related to those of published seawater proxies. The second suite includes banded quartz-pyroxene-amphibole +/- garnet rocks with minor magnetite from the so-called Akilia Association enclaves (in early Archaean granitoid gneisses) of the coastal region, some 150 km southwest of the IGB. Rocks of this type from one much publicised and highly debated locality (the island of Akilia) have been identified by some workers [Nature 384 (1996) 55; Geochim. Cosmochim. Acta 61 (1997) 2475] as BIF-facies, and their C-13-depleted signature in trace graphite interpreted as a proxy for earliest life on Earth. However, REE + Y patterns of the Akilia Association suite (except for one probably genuine magnetite-rich BIF from Ugpik) are inconsistent with a seawater origin. We agree with published geological and geochemical (including REE) work [Science 296 (2002) 1448] that most of the analysed Akilia rocks are not chemical sediments, and that C-isotopes in such rocks therefore cannot be used as biological proxies. Application of the REE + Y discriminant for the above two rock suites has been facilitated in this study by the use of MC-ICP technique which yields a more complete and precise REE + Y spectrum than was available in many previous studies. (C) 2004 Elsevier B.V. All rights reserved.

Signatures for generalized macroscopic superpositions

We develop criteria sufficient to enable detection of macroscopic coherence where there are not just two macroscopically distinct outcomes for a pointer measurement, but rather a spread of outcomes over a macroscopic range. The criteria provide a means to distinguish a macroscopic quantum description from a microscopic one based on mixtures of microscopic superpositions of pointer-measurement eigenstates. The criteria are applied to Gaussian-squeezed and spin-entangled states.

Particle number emissions and source signatures of an industrial facility

The work presented was conducted within the scope of a larger study investigating impacts of the Stuart Oil Shale project, a facility operating to the north of the industrial city of Gladstone, Australia. The aims of the investigations were threefold: (a) the identification of the plant signatures in terms of particle size distributions in the submicrometer range (13-830 nm) through stack measurements, (b) exploring the applicability of these signatures in tracing the source contributions at locations of interest, at a distance from the plant, and (c) assessing the contribution of the plant to the total particle number concentration at locations of interest. The stack measurements conducted for three different conditions of plant operation showed that the particle size distributions were bimodal with average modal count median diameters (CMDs) of 24 (SD 4) and 52 (SD 9) nm. The average of all the particle size distributions recorded within the plant sector at a site located 4.5 km from the plant, over the sampling period when the plant was operating, also showed a bimodal distribution. The modal CMDs in this case were 27 and 50 nm, similar to those at the stack. This bimodal size distribution is distinct from the size distribution of the most common ambient anthropogenic emission source, which is vehicle emissions, and can be considered as a signature of this source. The average contribution of the plant (for plant sector winds) was estimated to be (10.0 +/- 3.8) x 10(2) particles cm(-3) and constituted approximately a 50% increase over the local particle ambient concentration for plant sector winds. This increase in particle number concentration compared to the local background concentration, while high compared to the clean environment concentration, is not significant when compared to concentrations generally encountered in the urban environment of Brisbane.

3D protein structure matching by patch signatures

For determining functionality dependencies between two proteins, both represented as 3D structures, it is an essential condition that they have one or more matching structural regions called patches. As 3D structures for proteins are large, complex and constantly evolving, it is computationally expensive and very time-consuming to identify possible locations and sizes of patches for a given protein against a large protein database. In this paper, we address a vector space based representation for protein structures, where a patch is formed by the vectors within the region. Based on our previews work, a compact representation of the patch named patch signature is applied here. A similarity measure of two patches is then derived based on their signatures. To achieve fast patch matching in large protein databases, a match-and-expand strategy is proposed. Given a query patch, a set of small k-sized matching patches, called candidate patches, is generated in match stage. The candidate patches are further filtered by enlarging k in expand stage. Our extensive experimental results demonstrate encouraging performances with respect to this biologically critical but previously computationally prohibitive problem.

Specific lipidome signatures in central nervous system from methionine-restricted mice

Membrane lipid composition is an important correlate of the rate of aging of animals. Dietary methionine restriction (MetR) increases lifespan in rodents. The underlying mechanisms have not been elucidated but could include changes in tissue lipidomes. In this work, we demonstrate that 80% MetR in mice induces marked changes in the brain, spinal cord, and liver lipidomes. Further, at least 50% of the lipids changed are common in the brain and spinal cord but not in the liver, suggesting a nervous system-specific lipidomic profile of MetR. The differentially expressed lipids includes (a) specific phospholipid species, which could reflect adaptive membrane responses, (b) sphingolipids, which could lead to changes in ceramide signaling pathways, and (c) the physiologically redox-relevant ubiquinone 9, indicating adaptations in phase II antioxidant response metabolism. In addition, specific oxidation products derived from cholesterol, phosphatidylcholine, and phosphatidylethanolamine were significantly decreased in the brain, spinal cord, and liver from MetR mice. These results demonstrate the importance of adaptive responses of membrane lipids leading to increased stress resistance as a major mechanistic contributor to the lowered rate of aging in MetR mice. © 2013 American Chemical Society.

Improving the scientific reliability of biological detection of explosives by Canis familiaris: Active odour signatures and their implications

The use of canines as a method of detection of explosives is well established worldwide and those applying this technology range from police forces and law enforcement to humanitarian agencies in the developing world. Despite the recent surge in publication of novel instrumental sensors for explosives detection, canines are still regarded by many to be the most effective real-time field method of explosives detection. However, unlike instrumental methods, currently it is difficult to determine detection levels, perform calibration of the canines' ability or produce scientifically valid quality control checks. Accordingly, amongst increasingly strict requirements regarding forensic evidence admission such as Frye and Daubert, there is a need for better scientific understanding of the process of canine detection. ^ When translated to the field of canine detection, just like any instrumental technique, peer reviewed publication of the reliability, success and error rates, is required for admissibility. Commonly training is focussed towards high explosives such as TNT and Composition 4, and the low explosives such as Black and Smokeless Powders are added often only for completeness. ^ Headspace analyses of explosive samples, performed by Solid Phase Microextraction (SPME) paired with Gas Chromatography - Mass Spectrometry (GC-MS), and Gas Chromatography - Electron Capture Detection (GC-ECD) was conducted, highlighting common odour chemicals. The odour chemicals detected were then presented to previously trained and certified explosives detection canines, and the activity/inactivity of the odour determined through field trials and experiments. ^ It was demonstrated that TNT and cast explosives share a common odour signature, and the same may be said for plasticized explosives such as Composition C-4 and Deta Sheet. Conversely, smokeless powders were demonstrated not to share common odours. An evaluation of the effectiveness of commercially available pseudo aids reported limited success. The implications of the explosive odour studies upon canine training then led to the development of novel inert training aids based upon the active odours determined. ^

Size-based variation in intertissue comparisons of stable carbon and nitrogen isotopic signatures of bull sharks (Carcharhinus leucas) and tiger sharks (Galeocerdo cuvier)

Stable isotopes are important tools for understanding the trophic roles of elasmobranchs. However, whether different tissues provide consistent stable isotope values within an individual are largely unknown. To address this, the relationships among carbon and nitrogen isotope values were quantified for blood, muscle, and fin from juvenile bull sharks (Carcharhinus leucas) and blood and fin from large tiger sharks (Galeocerdo cuvier) collected in two different ecosystems. We also investigated the relationship between shark size and the magnitude of differences in isotopic values between tissues. Isotope values were significantly positively correlated for all paired tissue comparisons, but R2 values were much higher for δ13C than for δ15N. Paired differences between isotopic values of tissues were relatively small but varied significantly with shark total length, suggesting that shark size can be an important factor influencing the magnitude of differences in isotope values of different tissues. For studies of juvenile sharks, care should be taken in using slow turnover tissues like muscle and fin, because they may retain a maternal signature for an extended time. Although correlations were relatively strong, results suggest that correction factors should be generated for the desired study species and may only allow coarse-scale comparisons between studies using different tissue types.

Elemental microchemistry, fatty acid profile and geometric morphometrics signatures of goose barnacles (Pollicipes pollicipes) reveal their place of origin

Os produtos provenientes do mar têm um importante papel a nível socioeconómico, gastronómico e no legado cultural das comunidades piscatórias e costeiras de Portugal. O Percebe Pollicipes pollicipes é na Península Ibérica o recurso biológico do intertidal mais explorado pelo ser humano, devido à sua enorme popularidade e consequente procura, fazendo em algumas ocasiões disparar o preço de mercado até 150€/kg, gerando na sobreexploração dos stocks existentes. No entanto, na área marinha protegida da Reserva Natural da Berlenga, a apanha do percebe é fortemente regulada, tendo-se tornado em Portugal num bom exemplo da gestão de recursos marinhos. Com o intuito de prevenir fraudes, adulteração alimentar ou quaisquer outras práticas que possam induzir o consumidor em erro a Comissão Europeia declara que, o consumidor tem o direito de receber informação correcta acerca dos produtos que adquire, para além de definir regras para a correcta aplicação destas regras. Métodos analíticos que possibilitem identificar a origem do percebe, tornam-se deste modo importantes ferramantas no desenvolvimento de um selo de Denominação de Origem Protegida (DOP) e na gestão comercial do produto. Deste modo, investigou-se se o Percebe possui diferenças específicas de cada local de captura, através da forma da unha (CS), da composição microquímica da unha (EM) e do perfil de ácidos gordos (FA). A análise foi efectuada em indivíduos recolhidos em 3 locais na Reserva Natural das Berlengas e 7 ao longo de 300 km da costa Portuguesa. Em cada indivíduo analisou-se a forma da unha (CS) através da morfometria geométrica, a composição microquímica da unha (EM) através de ICP-MS e o perfil de ácidos gordos do músculo através de GC-FID. A análise das funções discriminantes (DFA) quer para a EM quer para a FA em separado obteve um elevado sucesso de reclassificação (77,6 % e 99% respectivamente, através de validação cruzada), enquanto que EM combinado com FA permitiu um sucesso de reclassificação de 100 %. A análise discriminante baseada apenas na CS, demonstrou um baixo sucesso (29,6 %) .Estes resultados demonstram que a composição microquímica da unha e o perfil de ácidos gordos do músculo de Percebe, poderá ser uma ferramenta de elevada importância, na determinação da origem do Percebe. Esta abordagem poderá ser utilizada para identificar a origem dos percebes comercializados, bem como ajudar no desenvolvimento de um selo DOP, aumentando ao mesmo tempo o valor potencial dos recursos biológicos provenientes de áreas marinhas protegidas em Portugal.

Mineralogical, geochemical and magnetic signatures of surface sediments from the Canadian Beaufort Shelf and Amundsen Gulf (Canadian Arctic)

Mineralogical, geochemical, magnetic, and siliciclastic grain-size signatures of 34 surface sediment samples from the Mackenzie-Beaufort Sea Slope and Amundsen Gulf were studied in order to better constrain the redox status, detrital particle provenance, and sediment dynamics in the western Canadian Arctic. Redox-sensitive elements (Mn, Fe, V, Cr, Zn) indicate that modern sedimentary deposition within the Mackenzie-Beaufort Sea Slope and Amundsen Gulf took place under oxic bottom-water conditions, with more turbulent mixing conditions and thus a well-oxygenated water column prevailing within the Amundsen Gulf. The analytical data obtained, combined with multivariate statistical (notably, principal component and fuzzy c-means clustering analyses) and spatial analyses, allowed the division of the study area into four provinces with distinct sedimentary compositions: (1) the Mackenzie Trough-Canadian Beaufort Shelf with high phyllosilicate-Fe oxide-magnetite and Al-K-Ti-Fe-Cr-V-Zn-P contents; (2) Southwestern Banks Island, characterized by high dolomite-K-feldspar and Ca-Mg-LOI contents; (3) the Central Amundsen Gulf, a transitional zone typified by intermediate phyllosilicate-magnetite-K-feldspar-dolomite and Al-K-Ti-Fe-Mn-V-Zn-Sr-Ca-Mg-LOI contents; and (4) mud volcanoes on the Canadian Beaufort Shelf distinguished by poorly sorted coarse-silt with high quartz-plagioclase-authigenic carbonate and Si-Zr contents, as well as high magnetic susceptibility. Our results also confirm that the present-day sedimentary dynamics on the Canadian Beaufort Shelf is mainly controlled by sediment supply from the Mackenzie River. Overall, these insights provide a basis for future studies using mineralogical, geochemical, and magnetic signatures of Canadian Arctic sediments in order to reconstruct past variations in sediment inputs and transport pathways related to late Quaternary climate and oceanographic changes.

Greenlandic Inuit show genetic signatures of diet and climate adaptation

The indigenous people of Greenland, the Inuit, have lived for a long time in the extreme conditions of the Arctic, including low annual temperatures, and with a specialized diet rich in protein and fatty acids, particularly omega-3 polyunsaturated fatty acids (PUFAs). A scan of Inuit genomes for signatures of adaptation revealed signals at several loci, with the strongest signal located in a cluster of fatty acid desaturases that determine PUFA levels. The selected alleles are associated with multiple metabolic and anthropometric phenotypes and have large effect sizes for weight and height, with the effect on height replicated in Europeans. By analyzing membrane lipids, we found that the selected alleles modulate fatty acid composition, which may affect the regulation of growth hormones. Thus, the Inuit have genetic and physiological adaptations to a diet rich in PUFAs.

Upper-Pleistocene terrace deposits in Mediterranean climate: geomorphological and source-rock control on mineral and geochemical signatures (Betic Cordillera, SE Spain)

Mineral and chemical composition of alluvial Upper-Pleistocene deposits from the Alto Guadalquivir Basin (SE Spain) were studied as a tool to identify sedimentary and geomorphological processes controlling its formation. Sediments located upstream, in the north-eastern sector of the basin, are rich in dolomite, illite, MgO and KB2BO. Downstream, sediments at the sequence base are enriched in calcite, smectite and CaO, whereas the upper sediments have similar features to those from upstream. Elevated rare-earth elements (REE) values can be related to low carbonate content in the sediments and the increase of silicate material produced and concentrated during soil formation processes in the neighbouring source areas. Two mineralogical and geochemical signatures related to different sediment source areas were identified. Basal levels were deposited during a predominantly erosive initial stage, and are mainly composed of calcite and smectite materials enriched in REE coming from Neogene marls and limestones. Then the deposition of the upper levels of the alluvial sequences, made of dolomite and illitic materials depleted in REE coming from the surrounding Sierra de Cazorla area took place during a less erosive later stage of the fluvial system. Such modification was responsible of the change in the mineralogical and geochemical composition of the alluvial sediments.