Strontium isotope ratios of planktonic foraminifera from late Neogene sediment samples

A curve describing the variation of the strontium isotopic composition of seawater for the late Neogene (9 to 2 Ma) was constructed from 87Sr/86Sr analyses of marine carbonate in five Deep Sea Drilling Project (DSDP) sites: 502, 519, 588, 590, and 593. The strontium isotopic composition of the oceans increased between 9 and 2 Ma with several changes in slope. From 9 to 5.5 Ma, 87Sr/86Sr values were nearly constant at ~0.708925. Between 5.5 and 4.5 Ma, 87Sr/86Sr ratios increased monotonically at a rate of not, vert, similar 1 * 10**-4 per million years. The steep slope during this interval provides the potential for high resolution strontium isotope stratigraphy across the Miocene/Pliocene boundary. The rate of change of 87Sr/86Sr decreases to near zero again during the interval 4.5-2.5 Ma, and ratios average 0.709025. The relatively rapid increase of 87Sr/86Sr between 5.5 and 4.5 Ma must be related to changes in the flux or average 87Sr/86Sr ratios of the major inputs of Sr to the oceans. Quantitative modelling of these inputs suggests that the increase was most probably caused by an increase in the dissolved riverine flux of strontium to the oceans, an increase in the average 87Sr/86Sr composition of river water, or some combination of these parameters. Modelling of this period as a transient-state requires a pulse-like increase in the input of 87Sr to the oceans between 5.5 and 4.5 Ma. Alternatively, the 5.5-4.5 Ma period can be modelled as a simple transition from one steady-state to another if the oceanic residence time of strontium was eight times less than the currently accepted value of 4 Ma. During the time interval of steep 87Sr/86Sr increase, other geochemical and sedimentologic changes also occur including an increase in sediment accumulation rates, a drop in the calcite compensation depth (CCD), and a decrease in the delta13C of dissolved bicarbonate (i.e., "carbon shift"). The simplest mechanism to explain 87Sr/86Sr variation and these related geochemical changes is to invoke an increase in the dissolved chemical fluxes carried by rivers to the oceans. This, in turn, implies increased chemical denudation rates of the continents and shelves during the late Neogene. The increase in chemical weathering rates is attributed to increased exposure of the continents by eustatic regression, intensified glacial/interglacial cycles, and accelerated rates of global tectonism beginning at 5.5 Ma during the latest Miocene.

Standard Errors for the Blinder-Oaxaca Decomposition

The decomposition technique introduced by Blinder (1973) and Oaxaca (1973) is widely used to study outcome differences between groups. For example, the technique is commonly applied to the analysis of the gender wage gap. However, despite the procedure's frequent use, very little attention has been paid to the issue of estimating the sampling variances of the decomposition components. We therefore suggest an approach that introduces consistent variance estimators for several variants of the decomposition. The accuracy of the new estimators under ideal conditions is illustrated with the results of a Monte Carlo simulation. As a second check, the estimators are compared to bootstrap results obtained using real data. In contrast to previously proposed statistics, the new method takes into account the extra variation imposed by stochastic regressors.

Methotrexate improves the health-related quality of life of children with juvenile idiopathic arthritis

Objectives: To examine the change in health-related quality of life (HRQOL) and its determinants in children with juvenile idiopathic arthritis (JIA) treated with methotrexate (MTX). Methods: Patients were extracted from the PRINTO clinical trial which aimed to evaluate the efficacy and safety profile of MTX administered in standard, intermediate or higher doses (10, 15 and 30 mg/m2/week respectively). Children with polyarticular-course JIA, who were less than 18 years and had a complete HRQOL assessment were included. Results: A total of 521 children were included. At baseline, patients with JIA showed poorer HRQOL (p<0.01) than healthy children. In 207/412 (50%) and 63 (15%) children, HRQOL values were 2 standard deviations below the mean of healthy controls in the physical and psychosocial summary scale, respectively. After 6 months of treatment with standard dose MTX, there was a statistically significant improvement in all HRQOL health concepts, particularly the physical ones. Similar improvements were observed in those who did not respond to a standard dose of MTX and were subsequently randomised to a higher dose. The presence of marked disability at baseline was associated with a fivefold increased risk of retaining poor physical health after 6 months of active treatment with standard dose MTX. Other less important determinants of retaining poor physical well-being were the baseline level of systemic inflammation, pain intensity and an antinuclear-antibody-negative status. Conclusions: MTX treatment produces a significant improvement across a wide range of HRQOL components, particularly in the physical domains, in patients with JIA.

Lead and strontium isotopic composition of some metalliferous and pelagic sediments and basalts at DSDP Leg 70 Holes

In recent years, metalliferous sediments have been discovered overlying newly generated oceanic crust in the East Pacific, North Atlantic, Indian Ocean, Red Sea, Gulf of Aden, and elsewhere (e.g., Boström, 1973; Lalou et al., 1977; Bischoff, 1969; Boström and Fisher, 1971; Cann et al., 1977, respectively). Such material has also been recovered by drilling from sediments lying upon older oceanic crust (Boström et al., 1972, 1976; Horowitz and Cronan, 1976). Hydrothermal circulation of seawater at a spreading ridge results in the leaching of Fe, Mn, and possibly other elements from the basaltic volcanic layer and their transport and discharge into ocean bottom waters, whereupon fine-grained Fe-Mn-rich precipitates form and settle into the ambient sediment (cf. Corliss, 1971; Dasch et al., 1971; Spooner and Fyfe, 1973; Bischoff and Dickson, 1975; Heath and Dymond, 1977; Corliss et al., 1979, Edmond et al., 1979). Mn-rich crusts have also been recovered from active ridges and are inferred to have formed in the vicinity of hydrothermal discharge areas (Scott et al., 1974; Moore and Vogt, 1976; Corliss et al., 1978; Hoffert et al., 1978). The source of the trace elements in the metalliferous deposits is generally not clear. They may be derived from seawater by adsorption onto the precipitates or crusts, or from hydrothermal solutions which have leached them from the basalts. Pb, however, can be used as a geochemical tracer because of the known isotopic compositional differences between oceanic basalts and seawater. Isotopic investigations of Pb in ferruginous sediments from the East Pacific have shown that it has been derived partly or mostly from a basaltic source (Bender et al., 1971; Dasch et al., 1971; Dymond et al., 1973). In the present study, Pb isotopic analyses have been made of a suite of metalliferous sediments (nontronite, Mn-oxide crust, Mn-Fe-oxide mud), pelagic sediments, and basalts from the Galapagos mounds area. The main purposes of the Pb study were to determine the source or sources of Pb in the metalliferous sediments, and whether or not stratigraphic variations exist in the isòtopic composition of Pb in the sediments.

Strontium- and lead-isotope composition of some basalts at DSDP Hole 69-504B

Seventeen whole-rock samples, generally taken at 25- to 50-meter intervals from 5 to 560 meters sub-basement in Deep Sea Drilling Project Hole 504B, were analyzed for 87Sr/86Sr ratios, and rubidium and strontium concentrations. Ten of these samples also were analyzed for Pb-isotope composition. Strontium-isotope ratios for eight samples from the upper 260 meters of the hole range from 0.70287 to 0.70377, with a mean of 0.70320. In the interval 330 to 560 meters, five samples have a restricted range of 0.70259 to 0.70279, with a mean of 0.70266, almost identical to the average value of fresh mid-ocean-ridge basalts. In the interval 260 to 330 meters, approximately intermediate strontium- isotope ratios are found. The higher 87Sr/86Sr ratios in the upper part of the hole can be interpreted in terms of strontium-isotope alteration during basalt-sea-water interaction. Relative to average fresh mid-ocean ridge basalts, the upper 260 meters of basalts are enriched by an average of about 9% in sea-water strontium 87Sr/86Sr = 0.7091). This Sr presumably is located in the smectites, which, as the main secondary minerals throughout the hole, replace olivine and matrix glass and locally fill vesicles (analyzed samples contained no veins). The strontium-isotope data strongly suggest that the integrated flux of sea water through the upper part of the Hole 504B crust has been greater than through the lower part. This is also suggested by (1) the common occurrence of Feoxide- hydroxide minerals as alteration products above 270 meters, but their near absence below 320 meters, (2) the presence of vein calcite above 320 meters, but its near absence below this level, and (3) the occurrence of vein pyrite only below a depth of 270 meters. Sea-water circulation in the lower basalts may have been partly restricted by the greater number of relatively impermeable massive lava flows below 230 meters sub-basement. Although sufficient sea water was present within the lower part of the hole to produce smectitic alteration products, the overall water /rock ratio was low enough to prevent significant modification of strontium-isotope ratios. Lead-isotope ratios of Hole 504B basalts form approximately linear arrays in plots of 208Pb/204Pb and 207Pb/204Pb versus 206Pb/204Pb. The arrays are similar to those reported for basalts from other mid-ocean ridges. There is no trend in Hole 504B lead-isotope ratios with vertical position in the basement. The arrays indicate that the lead-isotope composition of the upper mantle from which the Hole 504B basaltic melts were derived was inhomogeneous.

Hydrodynamic evaluation of kangaroo aortic valve matrices for tissue valve engineering

We evaluated the hydrodynamic performance of kangaroo aortic valve matrices (KMs) (19, 21, and 23 mm), as potential scaffolds in tissue valve engineering using a pulsatile left heart model at low and high cardiac outputs (COs) and heart rates (HRs) of 60 and 90 beats/min. Data were measured in two samples of each type, pooled in two CO levels (2.1 +/- 0.7 and 4.2 +/- 0.6 L/min; mean +/- standard errors on the mean), and analyzed using analysis of variance with CO level, HR, and valve type as fixed factors and compared to similar porcine matrices (PMs). Transvalvular pressure gradient (Delta P) was a function of HR (P < 0.001) and CO (P < 0.001) but not of valve type (P = 0.39). Delta P was consistently lower in KMs but not significantly different from PMs. The effective orifice area and performance index of kangaroo matrices was statistically larger for all sizes at both COs and HRs.

Mirror extreme BMI phenotypes associated with gene dosage at the chromosome 16p11.2 locus.

Both obesity and being underweight have been associated with increased mortality. Underweight, defined as a body mass index (BMI) ≤ 18.5 kg per m(2) in adults and ≤ -2 standard deviations from the mean in children, is the main sign of a series of heterogeneous clinical conditions including failure to thrive, feeding and eating disorder and/or anorexia nervosa. In contrast to obesity, few genetic variants underlying these clinical conditions have been reported. We previously showed that hemizygosity of a ∼600-kilobase (kb) region on the short arm of chromosome 16 causes a highly penetrant form of obesity that is often associated with hyperphagia and intellectual disabilities. Here we show that the corresponding reciprocal duplication is associated with being underweight. We identified 138 duplication carriers (including 132 novel cases and 108 unrelated carriers) from individuals clinically referred for developmental or intellectual disabilities (DD/ID) or psychiatric disorders, or recruited from population-based cohorts. These carriers show significantly reduced postnatal weight and BMI. Half of the boys younger than five years are underweight with a probable diagnosis of failure to thrive, whereas adult duplication carriers have an 8.3-fold increased risk of being clinically underweight. We observe a trend towards increased severity in males, as well as a depletion of male carriers among non-medically ascertained cases. These features are associated with an unusually high frequency of selective and restrictive eating behaviours and a significant reduction in head circumference. Each of the observed phenotypes is the converse of one reported in carriers of deletions at this locus. The phenotypes correlate with changes in transcript levels for genes mapping within the duplication but not in flanking regions. The reciprocal impact of these 16p11.2 copy-number variants indicates that severe obesity and being underweight could have mirror aetiologies, possibly through contrasting effects on energy balance.

Interactions between ecology, demography, capture stress, and profiles of corticosterone and glucose in a free-living population of Australian freshwater crocodiles

In this study we examined three aspects pertaining to adrenocortical responsiveness in free-ranging Australian freshwater crocodiles (Crocodylus johnstoni). First, we examined the ability of freshwater crocodiles to produce corticosterone in response to a typical capture-stress protocol. A second objective addressed the relationship between capture stress, plasma glucose and corticosterone. Next we examined if variation in basal and capture-stress-induced levels of plasma corticosterone was linked to ecological or demographic factors for individuals in this free-ranging population. Blood samples obtained on three field trips were taken from a cross-sectional sample of the population. Crocodiles were bled once during four time categories at 0, 0. 5, 6, and 10 h post-capture. Plasma corticosterone increased significantly with time post-capture. Plasma glucose also significantly increased with duration of capture-stress and exhibited a positive and significant relationship with plasma corticosterone. Significant variation in basal or stress induced levels of corticosterone in crocodiles was not associated with any ecological or demographic factors including sex, age class or the year of capture that the crocodiles were sampled from. However, three immature males had basal levels of plasma corticosterone greater than 2 standard deviations above the mean. While crocodiles exhibited a pronounced, adrenocortical and hyperglycaemic response to capture stress, limited variation in adrenocortical responsiveness due to ecological and demographic factors was not evident. This feature could arise in part because this population was sampled during a period of environmental benigness. (C) 2003 Elsevier Science (USA). All rights reserved.

Estudo teórico da contribuição a dose de partículas secundárias geradas por prótons de energias entre 100-200 MeV num phantom de músculo estriado

In the treatment plans in conventional Proton therapy are considered only the elastic interactions of protons with electrons and/or nuclei, it means, mainly ionization and coulomb excitation processes. As the energy needed to reach the deep tumors should be of several hundred of MeVs, certainly the nuclear inelastic channels are open. Only some previous studies of the contribution of these processes in the full dose have been made towards targets composed of water. In this study will be presented the results of the simulation of the processes of interaction of beams of protons in the range of 100-200 MeV of energy with a cylindrical phantom composed by striated muscle (ICRU), emphasizing in the contribution to total dose due to the deposition of energy by secondary particles alpha (α), deuterium (2H), tritium (3H), neutron (n) and hélio3 (3He), originated by nuclear inelastic processes. The simulations were performed by using the method of Monte Carlo, via the computer code MCNPX v2.50 (Monte Carlo N-Particle eXtended). The results will be shown demonstrated through the graphics of the deposited dose with or without nuclear interaction, the percentual of dose deposited by secondary particles, the radial dispersion of neutrons, as well as the multiplicity of secondary particles

The impact of inter-fraction set-up errors on the probability of pulmonary and cardiac complication in left-sided breast cancer patients

Purpose This study evaluated the impact of patient set-up errors on the probability of pulmonary and cardiac complications in the irradiation of left-sided breast cancer. Methods and Materials Using the CMS XiO Version 4.6 (CMS Inc., St Louis, MO) radiotherapy planning system's NTCP algorithm and the Lyman -Kutcher-Burman (LKB) model, we calculated the DVH indices for the ipsilateral lung and heart and the resultant normal tissue complication probabilities (NTCP) for radiation-induced pneumonitis and excess cardiac mortality in 12 left-sided breast cancer patients. Results Isocenter shifts in the posterior direction had the greatest effect on the lung V20, heart V25, mean and maximum doses to the lung and the heart. Dose volume histograms (DVH) results show that the ipsilateral lung V20 tolerance was exceeded in 58% of the patients after 1cm posterior shifts. Similarly, the heart V25 tolerance was exceeded after 1cm antero-posterior and left-right isocentric shifts in 70% of the patients. The baseline NTCPs for radiation-induced pneumonitis ranged from 0.73% - 3.4% with a mean value of 1.7%. The maximum reported NTCP for radiation-induced pneumonitis was 5.8% (mean 2.6%) after 1cm posterior isocentric shift. The NTCP for excess cardiac mortality were 0 % in 100% of the patients (n=12) before and after setup error simulations. Conclusions Set-up errors in left sided breast cancer patients have a statistically significant impact on the Lung NTCPs and DVH indices. However, with a central lung distance of 3cm or less (CLD <3cm), and a maximum heart distance of 1.5cm or less (MHD<1.5cm), the treatment plans could tolerate set-up errors of up to 1cm without any change in the NTCP to the heart.

Estimating the mean and standard deviation of concentration distributions using censored samples

Environmental data sets of pollutant concentrations in air, water, and soil frequently include unquantified sample values reported only as being below the analytical method detection limit. These values, referred to as censored values, should be considered in the estimation of distribution parameters as each represents some value of pollutant concentration between zero and the detection limit. Most of the currently accepted methods for estimating the population parameters of environmental data sets containing censored values rely upon the assumption of an underlying normal (or transformed normal) distribution. This assumption can result in unacceptable levels of error in parameter estimation due to the unbounded left tail of the normal distribution. With the beta distribution, which is bounded by the same range of a distribution of concentrations, $\rm\lbrack0\le x\le1\rbrack,$ parameter estimation errors resulting from improper distribution bounds are avoided. This work developed a method that uses the beta distribution to estimate population parameters from censored environmental data sets and evaluated its performance in comparison to currently accepted methods that rely upon an underlying normal (or transformed normal) distribution. Data sets were generated assuming typical values encountered in environmental pollutant evaluation for mean, standard deviation, and number of variates. For each set of model values, data sets were generated assuming that the data was distributed either normally, lognormally, or according to a beta distribution. For varying levels of censoring, two established methods of parameter estimation, regression on normal ordered statistics, and regression on lognormal ordered statistics, were used to estimate the known mean and standard deviation of each data set. The method developed for this study, employing a beta distribution assumption, was also used to estimate parameters and the relative accuracy of all three methods were compared. For data sets of all three distribution types, and for censoring levels up to 50%, the performance of the new method equaled, if not exceeded, the performance of the two established methods. Because of its robustness in parameter estimation regardless of distribution type or censoring level, the method employing the beta distribution should be considered for full development in estimating parameters for censored environmental data sets. ^

Meiofauna and the structure of the benthic community in the Iberian deep sea basin

1. On the cruises 3 and 15 of R.V. "Meteor" 6 grab samples, and 6 hauls with the 6 m Agassiztrawl were taken and at 2 stations the deep sea camera was lowered. This material gave quantitative results on the meiofauna and minimum counts of the macrofauna. 2. The nematodes constitute nearly 95% of the meiofauna, the copepoda only 2%. With increasing sediment depth the density of animals decrease gradually. In the uppermost centimeter of sediment 42.6% of the meiofauna are found while only 3.7% live in layer 6-7 cm. Meiofauna weight ranges from 0.6-5.7 mg/25 m**2 surface i.e. 0.24-2.8 g/m**2. 3. Mean numbers of individuals and weights show standard errors of 20-30 %. As an approximate average values for further considerations the weight of the meiofauna in the area was taken as 1 g/m**2 4. Quantitative information on the macrofauna is derived from the trawls and the photographs for the actinia Chitonanthus abyssorum only, which is found in the rate of 1 individual/36-72 m**2, but seems to be less abundant generally. 5. Animal density does not decrease steadily from nearshore to offshore biocoenoses, i.e. generally with increasing depth. The decrease is more pronounced for macro- than for meiofauna. For the deep sea the weight proportion of macrofauna : meiofauna is of the order of 1 : 1. 6. With the assumption, that adaptation of metabolism to deep sea conditions is similar in macro- and meiofauna total metabolism of invertebrates is ascribed to meiofauna to more than 80%. 7. The structure of the biocoenosis of the deep sea floor is characterized by the meiofauna living on and in the sediment and by the dominance of sediment feeders in the macrofauna. 8. Considering the large numbets and high partition rates of bacteria a comparative large part of the metabolism in the deep sea sediment must be ascribed to bacteria. This favours the hypothesis, that with increasing depth and decreasing addition of organic material to the sediment, the importance of meiofauna and microorganisms for total metabolism increases. 9. Considering the different modes of food transport to the deep sea environment, i.e. sinking of dead particles, transport by vertical migration of organisms, aggregation of organic particles, adsorption of dissoloved organic substance to inorganic particles, and heterotrophy, the sediment may be assumed to contain more food for invertebrates than the water above the bottom. 10. Suspensions feeders of macrofauna are fixed to hard substrates in the sediment surface. Some of them are shown to bend themselves down to the bottom in underwater photographs. This suggests the idea that some deep sea suspension feeders partly depend on food from the sediment surface, on which they feed directly.

What aspects of the scoliosis correction are most important to the teenager who has keyhole scoliosis correction surgery? A prospective series of 100 patients

Introduction. Surgical treatment of scoliosis is assessed in the spine clinic by the surgeon making numerous measurements on X-Rays as well as the rib hump. But it is important to understand which of these measures correlate with self-reported improvements in patients’ quality of life following surgery. The objective of this study was to examine the relationship between patient satisfaction after thoracoscopic (keyhole) anterior scoliosis surgery and standard deformity correction measures using the Scoliosis Research Society (SRS) adolescent questionnaire. Methods. A series of 100 consecutive adolescent idiopathic scoliosis patients received a single anterior rod via a keyhole approach at the Mater Children’s Hospital, Brisbane. Patients completed SRS outcomes questionnaires before surgery and again at 24 months after surgery. Multiple regression and t-tests were used to investigate the relationship between SRS scores and deformity correction achieved after surgery. Results. There were 94 females and 6 males with a mean age of 16.1 years. The mean Cobb angle improved from 52º pre-operatively to 21º for the instrumented levels post-operatively (59% correction) and the mean rib hump improved from 16º to 8º (51% correction). The mean total SRS score for the cohort was 99.4/120 which indicated a high level of satisfaction with the results of their scoliosis surgery. None of the deformity related parameters in the multiple regressions were significant. However, the twenty patients with the smallest Cobb angles after surgery reported significantly higher SRS scores than the twenty patients with the largest Cobb angles after surgery, but there was no difference on the basis of rib hump correction. Discussion. Patients undergoing thoracoscopic (keyhole) anterior scoliosis correction report good SRS scores which are comparable to those in previous studies. We suggest that the absence of any statistically significant difference in SRS scores between patients with and without rod or screw complications is because these complications are not associated with any clinically significant loss of correction in our patient group. The Cobb angle after surgery was the only significant predictor of patient satisfaction when comparing subgroups of patients with the largest and smallest Cobb angles after surgery.

Optical Properties of Nanocrystalline Potassium Lithium Niobate in the Glass System (100-x) TeO2-x(1.5K(2)O-Li2O-2.5Nb(2)O(5))

Optically clear glasses of various compositions in the system (100-x) TeO2-x(1.5K(2)O-Li2O-2.5Nb(2)O(5)) (2 <= x <= 12, in molar ratio) were prepared by the melt-quenching technique. The glassy nature of the as-quenched samples was established via differential scanning calorimetry (DSC). The amorphous and the crystalline nature of the as-quenched and heat-treated samples were confirmed by the X-ray powder diffraction and transmission electron microscopic (TEM) studies. Transparent glasses comprising potassium lithium niobate (K3Li2Nb5O15) microcrystallites on the surface and nanocrystallites within the glass were obtained by controlled heat-treatment of the as-quenched glasses just above the glass transition temperature (T-g). The optical transmission spectra of these glasses and glass-crystal composites of various compositions were recorded in the 200-2500 nm wavelength range. Various optical parameters such as optical band gap, Urbach energy, refractive index were determined. Second order optical non-linearity was established in the heat-treated samples by employing the Maker-Fringe method.