The oceanic cycles of the transition metals and their isotopes

The stable isotope systems of the transition metals potentially provide constraints on the current and past operation of the biological pump, and on the state of ocean redox in Earth history. Here we focus on two exemplar metals, nickel (Ni) and zinc (Zn). The oceanic dissolved pool of both elements is isotopically heavier than the known inputs, implying an output with light isotope compositions. The modern oceanic cycle of both these elements is dominated by biological uptake into photosynthesised organic matter and output to sediment. It is increasingly clear, however, that such uptake is associated with only very minor isotope fractionation. We suggest that the isotopic balance is instead closed by the sequestration of light isotopes to sulphide in anoxic and organic-rich sediments, so that it is ocean chemistry that controls these isotope systems, and suggesting a different but equally interesting array of questions in Earth history that can be addressed with these systems

On the origin of the marine zinc–silicon correlation

The close linear correlation between the distributions of dissolved zinc (Zn) and silicon (Si) in seawater has puzzled chemical oceanographers since its discovery almost forty years ago, due to the apparent lack of a mechanism for coupling these two nutrient elements. Recent research has shown that such a correlation can be produced in an ocean model without any explicit coupling between Zn and Si, via the export of Zn-rich biogenic particles in the Southern Ocean, consistent with the observation of elevated Zn quotas in Southern Ocean diatoms. Here, we investigate the physical and biological mechanisms by which Southern Ocean uptake and export control the large-scale marine Zn distribution, using suites of sensitivity simulations in an ocean general circulation model (OGCM) and a box-model ensemble. These simulations focus on the sensitivity of the Zn distribution to the stoichiometry of Zn uptake relative to phosphate (PO4), drawing directly on observations in culture. Our analysis reveals that OGCM model variants that produce a well-defined step between relatively constant, high Zn:PO4 uptake ratios in the Southern Ocean and low Zn:PO4 ratios at lower latitudes fare best in reproducing the marine Zn–Si correlation at both the global and the regional Southern Ocean scale, suggesting the presence of distinct Zn-biogeochemical regimes in the high- and low-latitude oceans that may relate to differences in physiology, ecology or (micro-)nutrient status. Furthermore, a study of the systematics of both the box model and the OGCM reveals that regional Southern Ocean Zn uptake exerts control over the global Zn distribution via its modulation of the biogeochemical characteristics of the surface Southern Ocean. Specifically, model variants with elevated Southern Ocean Zn:PO4 uptake ratios produce near-complete Zn depletion in the Si-poor surface Subantarctic Zone, where upper-ocean water masses with key roles in the global oceanic circulation are formed. By setting the main preformed covariation trend within the ocean interior, the subduction of these Zn- and Si-poor water masses produces a close correlation between the Zn and Si distributions that is barely altered by their differential remineralisation during low-latitude cycling. We speculate that analogous processes in the high-latitude oceans may operate for other trace metal micronutrients as well, splitting the ocean into two fundamentally different biogeochemical, and thus biogeographic, regimes

Re-assessing the influence of particle-hosted sulphide precipitation on the marine cadmium cycle

It has been inferred that the marine distributions of the micronutrient cadmium (Cd) and its stable isotope composition (expressed as δ114Cd) bear widespread and unambiguous evidence for loss of Cd from the shallow water column through the formation of particle-associated cadmium sulphide (CdS) in oxygen minimum zones (OMZs). In this review, we bring together elemental and isotopic datasets from the dissolved and particulate Cd pools in order to unravel the multiple, overlapping controls on the distribution of Cd and δ114Cd, and demonstrate that the global dataset challenges this view. By far the most important control on the marine Cd distribution is the extreme plasticity in the cadmium:phosphorus (Cd:P) stoichiometry of biological uptake and, in consequence, particulate export. We show that δ114Cd systematics in low-latitude OMZs that have been taken to reflect Cd loss in fact come about mainly through the interaction between the physical circulation and the variable stoichiometry of biological Cd uptake at high and low latitudes; water-column evidence for Cd loss is thus much less widespread than has previously been inferred. Subtle but consistent signals in particulate elemental and dissolved isotopic data from the open tropical Atlantic and Pacific Oceans allow us to identify the signal of a Cd loss associated with the oxycline of the shallow tropical subsurface, as has previously been suggested. However, this Cd loss appears to be ubiquitous throughout the tropics, rather than confined to oxygen-poor waters, speaking against CdS formation as the driving mechanism. Although its true identity remains unknown, this tropical Cd loss may be related to biological activity. Finally, we show how the processes we consider – the remineralisation of biogenic particles with variable Cd:P stoichiometry, and ubiquitous tropical oxycline Cd loss – bear upon the role of particle-hosted CdS formation in the marine mass balance of Cd, which is likely to be much smaller than recent estimates have suggested

An ex vivo, assessor blind, randomised, parallel group, comparative efficacy trial of the ovicidal activity of three pediculicides after a single application - melaleuca oil and lavender oil, eucalyptus oil and lemon tea tree oil, and a "suffocation" pediculicide

Background: There are two components to the clinical efficacy of pediculicides: (i) efficacy against the crawling-stages (lousicidal efficacy); and (ii) efficacy against the eggs (ovicidal efficacy). Lousicidal efficacy and ovicidal efficacy are confounded in clinical trials. Here we report on a trial that was specially designed to rank the clinical ovicidal efficacy of pediculicides. Eggs were collected, pre-treatment and post-treatment, from subjects with different types of hair, different coloured hair and hair of different length.Method: Subjects with at least 20 live eggs of Pediculus capitis (head lice) were randomised to one of three treatment-groups: a melaleuca oil (commonly called tea tree oil) and lavender oil pediculicide (TTO/LO); a eucalyptus oil and lemon tea tree oil pediculicide (EO/LTTO); or a "suffocation" pediculicide. Pre-treatment: 10 to 22 live eggs were taken from the head by cutting the single hair with the live egg attached, before the treatment (total of 1,062 eggs). Treatment: The subjects then received a single treatment of one of the three pediculicides, according to the manufacturers' instructions. Post-treatment: 10 to 41 treated live eggs were taken from the head by cutting the single hair with the egg attached (total of 1,183 eggs). Eggs were incubated for 14 days. The proportion of eggs that had hatched after 14 days in the pre-treatment group was compared with the proportion of eggs that hatched in the post-treatment group. The primary outcome measure was % ovicidal efficacy for each of the three pediculicides.Results: 722 subjects were examined for the presence of eggs of head lice. 92 of these subjects were recruited and randomly assigned to: the "suffocation" pediculicide (n = 31); the melaleuca oil and lavender oil pediculicide (n = 31); and the eucalyptus oil and lemon tea tree oil pediculicide (n = 30 subjects). The group treated with eucalyptus oil and lemon tea tree oil had an ovicidal efficacy of 3.3% (SD 16%) whereas the group treated with melaleuca oil and lavender oil had an ovicidal efficacy of 44.4% (SD 23%) and the group treated with the "suffocation" pediculicide had an ovicidal efficacy of 68.3% (SD 38%).Conclusion: Ovicidal efficacy varied substantially among treatments, from 3.3% to 68.3%. The "suffocation" pediculicide and the melaleuca oil and lavender oil pediculicide (TTO/LO) were significantly more ovicidal than eucalyptus oil and lemon tea tree oil pediculicide (EO/LTTO) (P < 0.0001). Ranking: 1. "Suffocation" pediculicide (68.3% efficacy against eggs); 2. Melaleuca oil and lavender oil (44.4%) pediculicide; 3. Eucalyptus oil and lemon tea tree oil (3.3%) pediculicide. The "suffocation" pediculicide and TTO/LO are also highly efficacious against the crawling-stages. Thus, the "suffocation" pediculicide and TTO/LO should be recommended as first line treatments.Trial Registration: The study was listed at the Australian/New Zealand Clinical Trial Registry (ANZCTR): reg. no. 12609000884202

Risk classification in an emergency room: agreement level between a Brazilian institutional and the Manchester Protocol

The aim of this study was to assess the level of agreement between an institutional protocol and the Manchester protocol for the risk assessment of patients attended in an emergency room of a public hospital in Belo Horizonte - MG - Brazil. This is a descriptive and comparative study, in which 382 patients' reports were evaluated and the risk was classified, using the institutional protocol and the Manchester protocol. Rates were calculated through weighted and unweighted kappa, in order to determine the level of agreement between the protocols. The results showed that the correlation between the protocols is average when considering that classification errors occurred between neighboring colors (kappa=0.48), and good when considering that classification errors occurred between extreme colors (kappa=0.61). The Manchester protocol increased the patients' level of priority of patients and has been considered more inclusive.Este estudio tuvo por objetivo verificar el grado de concordancia entre un protocolo institucional y el protocolo de Manchester para la clasificación de riesgo de pacientes atendidos en primeros auxilios de un hospital público de Belo Horizonte - MG - Brasil. Se trata de estudio descriptivo comparativo en el cual 382 fichas fueron evaluadas y, realizada la clasificación de riesgo utilizando los protocolos mencionados encima, a partir del registro realizado por los enfermeros. Índices kappa ponderado y no ponderado fueron calculados para determinar el grado de concordancia entre los protocolos. Los resultados mostraron que la concordancia entre los protocolos es media, cuando considerados los errores de clasificación ocurridos entre colores vecinos (kappa=0,48) y buena, cuando considerados los errores de clasificación ocurridos entre colores extremos (kappa=0,61). Se concluye que el protocolo de Manchester aumentó el nivel de prioridad de los pacientes, demostrando ser un protocolo que incluye más.Este estudo teve por objetivo verificar o grau de concordância entre um protocolo institucional e o protocolo de Manchester, para a classificação de risco de pacientes atendidos no pronto-socorro de um hospital público de Belo Horizonte, MG, Brasil. Trata-se de estudo descritivo comparativo, no qual 382 prontuários foram avaliados e realizada a classificação de risco, utilizando os protocolos mencionados acima, a partir do registro realizado pelos enfermeiros. Índices Kappa ponderado e não ponderado foram calculados para determinar o grau de concordância entre os protocolos. Os resultados mostraram que a concordância entre os protocolos é média, quando considerados os erros de classificação, ocorridos entre cores vizinhas (Kappa=0,48) e boa, quando considerados os erros de classificação, ocorridos entre cores extremas (Kappa=0,61). Conclui-se que o protocolo de Manchester aumentou o nível de prioridade dos pacientes, demonstrando ser protocolo mais inclusivo

Geographic Coincidence of Increased Malaria Transmission Hazard and Vulnerability Occurring at the Periphery of two Tanzanian Villages.

The goal of malaria elimination necessitates an improved understanding of any fine-scale geographic variations in transmission risk so that complementary vector control tools can be integrated into current vector control programmes as supplementary measures that are spatially targeted to maximize impact upon residual transmission. This study examines the distribution of host-seeking malaria vectors at households within two villages in rural Tanzania. Host-seeking mosquitoes were sampled from 72 randomly selected households in two villages on a monthly basis throughout 2008 using CDC light-traps placed beside occupied nets. Spatial autocorrelation in the dataset was examined using the Moran's I statistic and the location of any clusters was identified using the Getis-Ord Gi* statistic. Statistical associations between the household characteristics and clusters of mosquitoes were assessed using a generalized linear model for each species. For both Anopheles gambiae sensu lato and Anopheles funestus, the density of host-seeking females was spatially autocorrelated, or clustered. For both species, houses with low densities were clustered in the semi-urban village centre while houses with high densities were clustered in the periphery of the villages. Clusters of houses with low or high densities of An. gambiae s.l. were influenced by the number of residents in nearby houses. The occurrence of high-density clusters of An. gambiae s.l. was associated with lower elevations while An. funestus was also associated with higher elevations. Distance from the village centre was also positively correlated with the number of household occupants and having houses constructed with open eaves. The results of the current study highlight that complementary vector control tools could be most effectively targeted to the periphery of villages where the households potentially have a higher hazard (mosquito densities) and vulnerability (open eaves and larger households) to malaria infection

Iatrogenesis in Intensive Care Units: dramatization of Contemporary Bio/Ethical Problems

This qualitative investigation, based in Foucauldian analysis with approximations to the post-structuralism theoretical framework, explores iatrogenesis as one of the tensions in the nursing to do/to know which can be discursively articulated to bioethics and to technobiomedicine. The documentary sources and intensive interviews with nurses, permitted the activation of a reflection on the act of the nurse in a context permeated by the ever-present possibility of failure in both the procedure and in the conduct and, from this possibility, they should meet their obligation to correct this failure not so much or not only in knowledge, not so much or not only in law but in practice itself.Se trata de una investigación cualitativa, fundamentada en la perspectiva foucaultiana con aproximaciones en el referencial teórico post-estructuralista, explora las iatrogenias como una de las tensiones en el hacer/saber enfermería que pueden ser discursivamente articuladas a la bioética y a la tecnobiomedicina. Las fuentes documentales y de entrevistas con enfermeros intensivistas permitieron activar una reflexión sobre el actuar del enfermero en un contexto impregnado por la posibilidad siempre latente de fallar tanto en el procedimiento, como en la conducta y, a partir de esta posibilidad, estos profesionales encuentra que es su obligación corregir esta falla no tanto o no apenas en el conocimiento, no tanto o no apenas en la ley, pero más bien en la práctica de sí mismo.Esta é uma investigação qualitativa, balizada na analítica foucaultiana com aproximações ao referencial teórico pós-estruturalista, explora as iatrogenias como uma das tensões no fazer/saber enfermagem que podem ser discursivamente articuladas à bioética e à tecnobiomedicina. As fontes documentais e de entrevistas com enfermeiros(as) intensivistas permitiram ativar reflexão sobre o agir do(a) enfermeiro(a) em contexto permeado pela possibilidade, sempre latente, de falhar tanto no procedimento como na conduta, e, a partir dessa possibilidade, ele(a) encontra sua obrigação de corrigir essa falha não tanto ou não apenas no conhecimento, não tanto ou não apenas na lei, mas na prática de si mesmo

Neuromagnetic Evidence for Early Auditory Restoration of Fundamental Pitch

Background: Understanding the time course of how listeners reconstruct a missing fundamental component in an auditory stimulus remains elusive. We report MEG evidence that the missing fundamental component of a complex auditory stimulus is recovered in auditory cortex within 100 ms post stimulus onset. Methodology: Two outside tones of four-tone complex stimuli were held constant (1200 Hz and 2400 Hz), while two inside tones were systematically modulated (between 1300 Hz and 2300 Hz), such that the restored fundamental (also knows as ‘‘virtual pitch’’) changed from 100 Hz to 600 Hz. Constructing the auditory stimuli in this manner controls for a number of spectral properties known to modulate the neuromagnetic signal. The tone complex stimuli only diverged on the value of the missing fundamental component. Principal Findings: We compared the M100 latencies of these tone complexes to the M100 latencies elicited by their respective pure tone (spectral pitch) counterparts. The M100 latencies for the tone complexes matched their pure sinusoid counterparts, while also replicating the M100 temporal latency response curve found in previous studies. Conclusions: Our findings suggest that listeners are reconstructing the inferred pitch by roughly 100 ms after stimulus onset and are consistent with previous electrophysiological research suggesting that the inferential pitch is perceived i