RESUMO
Although Earth's continental crust is thought to have been derived from the mantle, the timing and mode of crust formation have proven to be elusive issues. The area of preserved crust diminishes markedly with age, and this can be interpreted as being the result of either the progressive accumulation of new crust or the tectonic recycling of old crust. However, there is a disproportionate amount of crust of certain ages, with the main peaks being 1.2, 1.9, 2.7 and 3.3 billion years old; this has led to a third model in which the crust has grown through time in pulses, although peaks in continental crust ages could also record preferential preservation. The 187Re-187Os decay system is unique in its ability to track melt depletion events within the mantle and could therefore potentially link the crust and mantle differentiation records. Here we employ a laser ablation technique to analyse large numbers of osmium alloy grains to quantify the distribution of depletion ages in the Earth's upper mantle. Statistical analysis of these data, combined with other samples of the upper mantle, show that depletion ages are not evenly distributed but cluster in distinct periods, around 1.2, 1.9 and 2.7 billion years. These mantle depletion events coincide with peaks in the generation of continental crust and so provide evidence of coupled, global and pulsed mantle-crust differentiation, lending strong support to pulsed models of continental growth by means of large-scale mantle melting events.
RESUMO
Early Medieval England is described historically as a time when people migrated from the Continent to English shores. This study tests the hypothesis that those buried in the Bowl Hole cemetery, Bamburgh, Northumberland were nonlocally born, because of its royal status. Ninety-one male and female adult, and nonadult, skeletons were studied. Isotope ratios of strontium ((87) Sr/(86) Sr) and oxygen (δ(18) O) were generated for 78 individuals (28 females, 27 males, five "adults," 18 nonadults). The mean Sr value for human enamel was 0.71044, standard deviation (sd) 0.001, and the mean O (δw) value is -5.9, sd 1.6. Additionally, animal tooth enamel (mean Sr value 0.710587, sd 0.001; mean O value -6.5, sd 1.5), local soil (mean Sr value 0.709184, sd 0.0006), snail shells (mean Sr value 0.708888, sd 0.0001), and soil samples from a 5 km transect heading inland (mean Sr value 0.709121, sd 0.0003), were analyzed for an indication of the isotopic composition of bioavailable Sr in the modern environment and to assess the impact of sea-spray; water samples from a well, local rivers, and standing water were analyzed for local δ(18) O values (mean O value -6.4, relative to VSMOW, sd 2.8). Over 50% of those buried at Bamburgh were nonlocal. All ages and both sexes produced "nonlocal" signatures; some suggested childhood origins in Scandinavia, the southern Mediterranean or North Africa. Stature and other indicators of health status indicated differences in quality of life between local and migrant groups. These differences did not extend to burial practices.
Assuntos
Exoesqueleto/química , Osso e Ossos/química , Esmalte Dentário/química , Caramujos/química , Solo/química , Migrantes , Adolescente , Adulto , Animais , Cemitérios , Criança , Pré-Escolar , Inglaterra , Feminino , Nível de Saúde , História Medieval , Humanos , Lactente , Masculino , Espectrometria de Massas , Pessoa de Meia-Idade , Isótopos de Oxigênio/metabolismo , Isótopos de Estrôncio/metabolismoRESUMO
Treponematosis has been one of the most studied and debated infectious diseases in paleopathology, particularly from the standpoint of its origin, evolution, and transmission. This study links evidence for treponematosis in skeletons from the 14th-16th century AD cemetery of the Augustinian friary of Hull Magistrates Court, England, with data from stable isotope analysis to test the hypothesis that the people with treponemal disease buried at this site were not locally born and raised. The objective is to explore the potential of using stable isotope data to track the place of origin and extent of mobility of individuals with an infectious disease. Dental enamel samples of 12 skeletons were selected for strontium ((87) Sr/(86) Sr ratio) and oxygen (δ(18) O) stable isotope analysis based on the presence (six - diseased) or absence (six - controls) of bone changes associated with treponemal disease. The oxygen isotope ratios of all but three individuals (1047, 1121, 823) overlapped at two standard deviations with the inferred local precipitation range, and only one individual (1216) had a strontium isotope ratio outside the regional range. Two of the four had probable/possible treponemal bone changes. Those with treponemal bone changes were not demonstrably more likely to be migrants than those without such lesions. However, because of extensive documentary evidence for trade with the Baltic Sea area, and for merchants from towns such as Stralsund, Danzig and Elbing being in Hull, it is very plausible that the four migrants came from the Baltic area or even southern Sweden.
Assuntos
Isótopos de Oxigênio/análise , Isótopos de Estrôncio/análise , Migrantes/estatística & dados numéricos , Infecções por Treponema/história , Infecções por Treponema/patologia , Adolescente , Adulto , Antropologia Física , Osso e Ossos/química , Osso e Ossos/patologia , Cemitérios , Inglaterra , Feminino , História do Século XV , História do Século XVI , História Medieval , Humanos , Masculino , Pessoa de Meia-Idade , Migrantes/históriaRESUMO
Unit managers do need formal supervisory training. Training should focus on their approach to the decision making process as well as their performance within it. Quality circle training was deemed most appropriate, because it focuses on team management and the development of skills needed to handle interactions in team settings.
Assuntos
Pessoal Administrativo/educação , Unidades Hospitalares/organização & administração , Capacitação em Serviço , Humanos , Inquéritos e Questionários , Estados UnidosRESUMO
The study indicates the use of participative managerial techniques can improve the quality and quantity of communications within HUM systems; foster greater cooperation from nurses, as reflected in their willingness to do extra work; and reduce nurse aggression toward unit managers and system procedures, as reflected in chronic complaints.
Assuntos
Atitude do Pessoal de Saúde , Participação nas Decisões , Serviço Hospitalar de Enfermagem/organização & administração , Supervisão de Enfermagem , Gestão de Recursos Humanos , Humanos , Inquéritos e Questionários , Estados UnidosRESUMO
Coastal areas and estuaries are particularly sensitive to metal contamination from anthropogenic sources and in the last few decades the study of space-time distribution and variation of metals has been extensively researched. The Gulf of Cadiz is no exception, with several rivers draining one of the largest concentrations of sulphide deposits in the world, the Iberian Pyrite Belt (IPB). Of these rivers, the Guadiana, one of the most important in the Iberian Peninsula, together with smaller rivers like the Tinto and Odiel, delivers a very high metal load to the adjacent coastal areas. The purpose of this work was to study the source and impact of lead (Pb) drained from historical or active mining areas in the IPB on the activity of a Pb inhibited enzyme (δ-aminolevulinic acid dehydratase, ALAD) in several bivalve species along the Gulf of Cadiz. Seven marine species (Chamelea gallina, Mactra corallina, Donax trunculus, Cerastoderma edule, Mytilus galloprovincialis, Scrobicularia plana and Crassostrea angulata) were collected at 12 sites from Mazagón, near the mouth of the rivers Tinto and Odiel (Spain), to Cacela Velha (Ria Formosa lagoon system, Portugal). Lead concentrations, ALAD activity and lead isotope ratios ((206)Pb/(204)Pb, (207)Pb/(204)Pb and (208)Pb/(204)Pb) were determined in the whole soft tissues. The highest Pb concentrations were determined in S. plana (3.50±1.09 µg g(-1) Pb d.w.) and D. trunculus (1.95±0.10 µg g(-1) Pb d.w.), while M. galloprovincialis and C. angulata showed the lowest Pb levels (<0.38 µg g(-1) Pb d.w.). In general, ALAD activity is negatively correlated with total Pb concentration. However this relationship is species dependent (e.g. linear for C. gallina ALAD=-0.36[Pb]+0.79; r=0.837; or exponential for M. galloprovincialis ALAD=2.48e(-8.3[Pb]); r=0.911). This indicates that ALAD activity has considerable potential as a biomarker of Pb and moreover, in marine bivalve species with different feeding habits. Lead isotope data showed significant seasonal and spatial changes in bivalve isotopic composition reflecting seasonal and geographic differences in bioaccumulation. Within the study area, Pb can be modelled as a mixing between geogenic Pb and mine-related, discharges of Pb from the IPB. For some sites at the mouth of the Guadiana River, the bivalves show contamination from other anthropogenic sources, such as leaded boat/aviation fuel and/or leaded paint. Finally, the study demonstrates convincingly the need to consider species-specific variation when using bivalve ALAD activity as a biomarker for Pb.
Assuntos
Bivalves/metabolismo , Monitoramento Ambiental/métodos , Chumbo/toxicidade , Mineração , Sintase do Porfobilinogênio/metabolismo , Rios/química , Água do Mar/química , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Monitoramento Ambiental/estatística & dados numéricos , Isótopos/análise , Chumbo/análise , Espanha , Especificidade da Espécie , Poluentes Químicos da Água/análiseRESUMO
The geochemical signature of diamond-forming fluids can be used to unravel diamond-forming processes and is of potential use in the detection of so-called 'conflict' diamonds. While fluid-rich fibrous diamonds can be analyzed by a variety of techniques, very few data have been published for fluid-poor, gem-quality diamonds because of their very low impurity levels. Here we present a new ICPMS-based (ICPMS: inductively coupled plasma mass spectrometry) method for the analysis of trace element concentrations within fluid-poor, gem-quality diamonds. The method employs a closed-system laser ablation cell. Diamonds are ablated and the products trapped for later pre-concentration into solutions that are analyzed by sector-field ICPMS. We show that our limits of quantification for a wide range of elements are at the sub-pg to low pg level. The method is applied to a suite of 10 diamonds from the Cullinan Mine (previously known as Premier), South Africa, along with other diamonds from Siberia (Mir and Udachnaya) and Venezuela. The concentrations of a wide range of elements for all the samples (expressed by weight in the solid) are very low, with rare earth elements along with Y, Nb, Cs ranging from 0.01 to 2 ppb. Large ion lithophile elements (LILE) such as Rb and Ba vary from 1 to 30 ppb. Ti ranges from ppb levels up to 2 ppm. From the combined, currently small data set we observe two kinds of diamond-forming fluids within gem diamonds. One group has enrichments in LILE over Nb, whereas a second group has normalized LILE abundances more similar to those of Nb. These two groups bear some similarity to different groups of fluid-rich diamonds, providing some supporting evidence of a link between the parental fluids for both fluid-inclusion-rich and gem diamonds.
RESUMO
A pharmacokinetic-pharmacodynamic study was carried out to investigate the feasibility and potential importance of therapeutic monitoring following high-dose carboplatin treatment in children. High-dose carboplatin was administered over 3 or 5 days, with the initial dose based on renal function, to achieve target area under the plasma concentration-time curve (AUC) values of 21 or 20 mg ml(-1).min, respectively. Dose adjustment was carried out based on observed individual daily AUC values, to obtain the defined target exposures. Platinum-DNA adduct levels were determined in peripheral blood leucocytes and toxicity data were obtained. Twenty-eight children were studied. Based on observed AUC values, carboplatin dose adjustment was performed in 75% (21 out of 28) patients. Therapeutic monitoring resulted in the achievement of carboplatin exposures within 80-126% of target AUC values, as compared to estimated exposures of 65-213% of target values without dose adjustment. The carboplatin AUC predicted with no dose modification was positively correlated with pretreatment glomerular filtration rate (GFR) values. Higher GFR values were observed in those patients who would have experienced AUC values >25% above the target AUC than those patients attaining AUC values >25% below the target AUC, following renal function-based dosing. Platinum-DNA adduct levels correlated with observed AUC values on day 1 of carboplatin and increased over a 5-day course of treatment. Real-time monitoring of carboplatin pharmacokinetics with adaptive dosing is both feasible and necessary for the attainment of consistent AUC values in children receiving high-dose carboplatin treatment. Pharmacodynamic data suggest a strong correlation between carboplatin pharmacokinetics and the drug-target interaction.
Assuntos
Antineoplásicos/administração & dosagem , Antineoplásicos/farmacocinética , Carboplatina/administração & dosagem , Carboplatina/farmacocinética , Adutos de DNA/sangue , Neoplasias/tratamento farmacológico , Adolescente , Adulto , Área Sob a Curva , Criança , Pré-Escolar , Ensaios Clínicos como Assunto , Relação Dose-Resposta a Droga , Feminino , Taxa de Filtração Glomerular , Humanos , Lactente , MasculinoRESUMO
The Miles system of ageing, based upon analysis of the rate of molar wear, was evaluated using the available dental sample from Tepe Hissar, Iran. The independently estimated ages for the mandibles and maxillae of the same individuals were found to be highly correlated (r = 0.87, p less than 0.001). Ages of a subsample of the dentitions were compared with skeletal ages for the same individuals estimated from pubic symphyseal faces and found to be significantly correlated (r = 0.82, p less than 0.005) with no significant differences in the mean ages. Although a complete evaluation of the Miles method would require its testing on a controlled population, the available dental sample from Tepe Hissar provided evidence of the reliability and validity of the Miles method of ageing archeological populations on the basis of dental wear. Due to selective retention of burial remains, the available skeletal sample from Tepe Hissar I-III is not representative of the human populations of the site and can not be used to generate meaningful demographic statistics.
Assuntos
Determinação da Idade pelos Dentes , Determinação da Idade pelo Esqueleto , Humanos , Irã (Geográfico) , Mandíbula/anatomia & histologia , Maxila/anatomia & histologia , Métodos , Abrasão DentáriaRESUMO
The continental lithospheric mantle (CLM) is a small-volumed (ca. 2.5% of the total mantle), chemically distinct mantle reservoir that has been suggested to play a role in the source of continental and oceanic magmatism. It is our most easily identifiable reservoir for preserving chemical heterogeneity in the mantle. Petrological and geophysical constraints indicate that the maximum depth of the CLM is ca. 250 km. There is a clear secular variation of CLM composition, such that CLM formed in the last 2 Gyr is less depleted and therefore less dynamically stable than ancient CLM formed in the Archean. We present new trace-element data for kimberlite-hosted lithospheric peridotites and metasomites. These data, combined with other data for spinel peridotites from non-cratonic regions, show that neither hydrous nor anhydrous lithospheric mantle xenoliths make suitable sources for continental or oceanic basalts. Addition of a hydrous phase, either amphibole or phlogopite, to depleted peridotite results in positive Nb and Ti anomalies that are the opposite of those predicted for some flood-basalt sources on the basis of their trace-element abundances. Overall, the Sr and Nd isotopic composition of cratonic and non-cratonic CLM is close to bulk Earth, with cratonic CLM showing small numbers of extreme compositions. Thus, while the CLM is certainly ancient in many locations, its average composition is not significantly 'enriched' over primitive upper mantle, in terms of either radiogenic isotopes or trace elements. These characteristics, plus a change in lithospheric chemistry with depth, indicate that the elemental and isotopic composition of lithospheric mantle likely to be re-incorporated into convecting mantle via delamination/thermal erosion processes is probably not very distinct from that of the convecting mantle. These observations lead us to question the requirement for CLM participation in the source of oceanic magmas and to promote consideration of a mantle that is chemically heterogeneous on all scales. Hf and Nd isotope compositions identify a distinctive source component in deeply derived alkaline volcanics associated with continents. This component cannot be constrained to the CLM but may originate from a deeper reservoir of ancient, subducted oceanic crust stored in the mantle.