123 research outputs found
Cadmium transport in sediments by tubificid bioturbation: An assessment of model complexity
Biogeochemistry of metals in aquatic sediments is strongly influenced by bioturbation. To determine the effects of biological transport on cadmium distribution in freshwater sediments, a bioturbation model is explored that describes the conveyor-belt feeding of tubificid oligochaetes. A stepwise modelling strategy was adopted to constrain the many parameters of the model: (i) the tubificid transport model was first calibrated on four sets of microspheres (inert solid tracer) profiles to constrain tubificid transport; (ii) the resulting transport coefficients were subsequently applied to simulate the distribution of both particulate and dissolved cadmium. Firstly, these simulations provide quantitative insight into the mechanism of tubificid bioturbation. Values of transport coefficients compare very well with the literature, and based on this, a generic model of tubificid bioturbation is proposed. Secondly, the application of the model to cadmium dataset sheds a light on the behaviour of cadmium under tubificid bioturbation. Cadmium enters the sediment in two ways. In one pathway, cadmium enters the sediment in the dissolved phase, is rapidly absorbed onto solid particles, which are then rapidly transported to depth by the tubificids. In the other pathway, cadmium is adsorbed to particles in suspension in the overlying water, which then settle on the sediment surface, and are transported downwards by bioturbation. In a final step, we assessed the optimal model complexity for the present dataset. To this end, the two-phase conveyor-belt model was compared to two simplified versions. A solid phase-only conveyorbelt model also provides good results: the dissolved phase should not be explicitly incorporated because cadmium adsorption is fast and bioirrigation is weak. Yet, a solid phase-only biodiffusive model does not perform adequately, as it does not mechanistically capture the conveyor-belt transport at short time-scales
Guide to best practices for ocean CO2 measurements
CHAP 1 - Introduction to the Guide
CHAP 2 - Solution chemistry of carbon dioxide in sea water
CHAP 3 - Quality assurance
CHAP 4 - Recommended standard operating procedures (SOPs)
SOP 1 - Water sampling for the parameters of the oceanic carbon dioxide system
SOP 2 - Determination of total dissolved inorganic carbon in sea water
SOP 3a - Determination of total alkalinity in sea water using a closed-cell titration
SOP 3b - Determination of total alkalinity in sea water using an open-cell titration
SOP 4 - Determination of p(CO2) in air that is in equilibrium with a discrete sample of sea water
SOP 5 - Determination of p(CO2) in air that is in equilibrium with a continuous stream of sea water
SOP 6a - Determination of the pH of sea water using a glass/reference electrode cell
SOP 6b - Determination of the pH of sea water using the indicator dye m-cresol purple
SOP 7 - Determination of dissolved organic carbon and total dissolved nitrogen in sea water
SOP 7 en Español - Determinacion de carbono organico disuelto y nitrogeno total disuelto en agua de mar
SOP 11 - Gravimetric calibration of the volume of a gas loop using water
SOP 12 - Gravimetric calibration of volume delivered using water
SOP 13 - Gravimetric calibration of volume contained using water
SOP 14 - Procedure for preparing sodium carbonate solutions for the calibration of coulometric CT measurements
SOP 21 - Applying air buoyancy corrections
SOP 22 - Preparation of control charts
SOP 23 - Statistical techniques used in quality assessment
SOP 24 - Calculation of the fugacity of carbon dioxide in the pure gas or in air
CHAP 5 - Physical and thermodynamic data
Errata - to the hard copy of the Guide to best practices for ocean CO2 measurement
High-dose chemotherapy (HDCT) with hematopoietic stem cell transplantation (HSCT) in high-risk breast cancer (BC) patients with ≥4 involved axillary lymph nodes (ALN): 20-year follow-up of a randomized phase 3 study
Relative expression of mRNAs related to cavitation process in bovine embryos produced in vivo and in vitro
2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation
Changing geographical patterns and trends in cancer incidence in children and adolescents in Europe, 1991–2010 (Automated Childhood Cancer Information System): a population-based study
Background: A deceleration in the increase in cancer incidence in children and adolescents has been reported in several national and regional studies in Europe. Based on a large database representing 1·3 billion person-years over the period 1991–2010, we provide a consolidated report on cancer incidence trends at ages 0–19 years. Methods: We invited all population-based cancer registries operating in European countries to participate in this population-based registry study. We requested a listing of individual records of cancer cases, including sex, age, date of birth, date of cancer diagnosis, tumour sequence number, primary site, morphology, behaviour, and the most valid basis of diagnosis. We also requested population counts in each calendar year by sex and age for the registration area, from official national sources, and specific information about the covered area and registration practices. An eligible registry could become a contributor if it provided quality data for all complete calendar years in the period 1991–2010. Incidence rates and the average annual percentage change with 95% CIs were reported for all cancers and major diagnostic groups, by region and overall, separately for children (age 0–14 years) and adolescents (age 15–19 years). We examined and quantified the stability of the trends with joinpoint analyses. Findings: For the years 1991–2010, 53 registries in 19 countries contributed a total of 180 335 unique cases. We excluded 15 162 (8·4%) of 180 335 cases due to differing practices of registration, and considered the quality indicators for the 165 173 cases included to be satisfactory. The average annual age-standardised incidence was 137·5 (95% CI 136·7–138·3) per million person-years and incidence increased significantly by 0·54% (0·44–0·65) per year in children (age 0–14 years) with no change in trend. In adolescents, the combined European incidence was 176·2 (174·4–178·0) per million person-years based on all 35 138 eligible cases and increased significantly by 0·96% (0·73–1·19) per year, although recent changes in rates among adolescents suggest a deceleration in this increasing trend. We observed temporal variations in trends by age group, geographical region, and diagnostic group. The combined age-standardised incidence of leukaemia based on 48 458 cases in children was 46·9 (46·5–47·3) per million person-years and increased significantly by 0·66% (0·48–0·84) per year. The average overall incidence of leukaemia in adolescents was 23·6 (22·9–24·3) per million person-years, based on 4702 cases, and the average annual change was 0·93% (0·49–1·37). We also observed increasing incidence of lymphoma in adolescents (average annual change 1·04% [0·65–1·44], malignant CNS tumours in children (average annual change 0·49% [0·20–0·77]), and other tumours in both children (average annual change 0·56 [0·40–0·72]) and adolescents (average annual change 1·17 [0·82–1·53]). Interpretation: Improvements in the diagnosis and registration of cancers over time could partly explain the observed increase in incidence, although some changes in underlying putative risk factors cannot be excluded. Cancer incidence trends in this young population require continued monitoring at an international level. Funding: Federal Ministry of Health of the Federal German Government, the European Union's Seventh Framework Programme, and International Agency for Research on Cancer
Regulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in rat liver and Morris hepatomas 5123C, 9618A and 5123t.c.
Characteristics of 3-hydroxy-3-methylglutaryl-CoA reductase from normal liver, Morris hepatomas 5123C, 5123t.c. and 9618A, and host liver were studied. Animals were fed on control and 5%-cholesterol diets. Microsomal membranes from all tissues were found to accumulate cholesterol after 3 days on the 5%-cholesterol diet. The enzyme of the tumours showed no feedback inhibition by dietary cholesterol, and that of host liver gave a variable response, whereas that of control liver was constantly inhibited by 90% or more. Arrhenius-plot analysis was conducted on the microsomal enzyme isolated from the various tissues. Control animals showed that the phase transition present at 27°C was removed when animals were fed on 5%-cholesterol diet for 12 h. The hepatomas failed to show this change even after 3 days of 5%-cholesterol diet and a significant increase in microsomal cholesterol. This failure to remove the break in Arrhenius plots also occurred in host liver, even though enzyme inhibition occurred. The reason why hepatomas fail to regulate 3-hydroxy-3-methylglutaryl-CoA reductase activity in response to dietary cholesterol may be a decreased membrane-enzyme interaction
Long-term trends in aerosol and precipitation composition over the western North Atlantic Ocean at Bermuda
Since the 1980s, emissions of SO2 and NOx (NO +
NO2) from anthropogenic sources in the United States (US), Canada,
and Europe have decreased significantly suggesting that the export of
oxidized S and N compounds from surrounding continents to the atmosphere
overlying the North Atlantic Ocean (NAO) has also decreased. The chemical
compositions of aerosols and precipitation sampled daily on Bermuda
(32.27° N, 64.87° W) from 1989 to 1997 and from 2006 to
2009 were evaluated to quantify the magnitudes, significance, and
implications of associated tends in atmospheric composition. The chemical
data were stratified based on FLEXPART (FLEXible PARTicle dispersion model)
retroplumes into four discrete transport regimes: westerly flow from eastern
North America (NEUS/SEUS); easterly trade-wind flow from northern Africa and
the subtropical NAO (Africa); long, open-ocean, anticyclonic flow around the
Bermuda High (Oceanic); and transitional flow from the relatively clean open
ocean to the polluted eastern North America (North). Based on all data,
annual average concentrations of non-sea-salt (nss) SO42– associated
with aerosols and annual volume-weighted-average (VWA) concentrations in
precipitation decreased significantly (by 22% and 49%,
respectively) whereas annual VWA concentrations of NH4+ in
precipitation increased significantly (by 70%). Corresponding trends in
aerosol and precipitation NO3– and of aerosol NH4+ were
insignificant. Nss SO42– in precipitation under NEUS/SEUS and Oceanic
flow decreased significantly (61% each) whereas corresponding trends in
particulate nss SO42– under both flow regimes were insignificant.
Trends in precipitation composition were driven in part by decreasing
emissions of SO2 over upwind continents and associated decreases in
anthropogenic contributions to nss SO42– concentrations. Under
NEUS/SEUS and Oceanic flow, the ratio of anthropogenic to biogenic
contributions to nss SO42– in the column scavenged by precipitation
were relatively greater than those in near surface aerosol, which implies
that, for these flow regimes, precipitation is a better indicator of overall
anthropogenic impacts on the lower troposphere. Particulate nss SO42–
under African flow also decreased significantly (34%) whereas the
corresponding decrease in nss SO42– associated with precipitation was
insignificant. We infer that these trends were driven in part by reductions
in the emissions and transport of oxidized S compounds from Europe. The lack
of significant trends in NO3– associated with aerosols and
precipitation under NEUS/SEUS flow is notable in light of the large decrease
(37%) in NOx emissions in the US and Canada over the period of
record. Rapid chemical processing of oxidized N in marine air contributed to
this lack of correspondence. Decreasing ratios of nss SO42– to
NH4+ and the significant decreasing trend in precipitation acidity
(37%) indicate that the total amount of acidity in the multiphase
gas–aerosol system in the western NAO troposphere decreased over the period
of record. Decreasing aerosol acidities would have shifted the phase
partitioning of total NH3 (NH3 + particulate NH4+ towards
the gas phase thereby decreasing the atmospheric lifetime of total NH3
against wet plus dry deposition. The trend of increasing NH4+ in
precipitation at Bermuda over the period of record suggests that NH3
emissions from surrounding continents also increased. Decreasing particulate
nss SO42– in near-surface air under NEUS/SEUS flow over the period of
record implies that the corresponding shortwave scattering and absorption by
nss S and associated aerosols constituents also decreased. These changes in
radiative transfer suggest a corresponding lower limit for net warming over
the period in the range of 0.1–0.3 W m–2
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