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1.
Am J Hypertens ; 33(3): 243-251, 2020 03 13.
Article in English | MEDLINE | ID: mdl-31730171

ABSTRACT

BACKGROUND: Studies have shown that self-monitoring of blood pressure (BP) is effective when combined with co-interventions, but its efficacy varies in the presence of some co-morbidities. This study examined whether self-monitoring can reduce clinic BP in patients with hypertension-related co-morbidity. METHODS: A systematic review was conducted of articles published in Medline, Embase, and the Cochrane Library up to January 2018. Randomized controlled trials of self-monitoring of BP were selected and individual patient data (IPD) were requested. Contributing studies were prospectively categorized by whether they examined a low/high-intensity co-intervention. Change in BP and likelihood of uncontrolled BP at 12 months were examined according to number and type of hypertension-related co-morbidity in a one-stage IPD meta-analysis. RESULTS: A total of 22 trials were eligible, 16 of which were able to provide IPD for the primary outcome, including 6,522 (89%) participants with follow-up data. Self-monitoring was associated with reduced clinic systolic BP compared to usual care at 12-month follow-up, regardless of the number of hypertension-related co-morbidities (-3.12 mm Hg, [95% confidence intervals -4.78, -1.46 mm Hg]; P value for interaction with number of morbidities = 0.260). Intense interventions were more effective than low-intensity interventions in patients with obesity (P < 0.001 for all outcomes), and possibly stroke (P < 0.004 for BP control outcome only), but this effect was not observed in patients with coronary heart disease, diabetes, or chronic kidney disease. CONCLUSIONS: Self-monitoring lowers BP regardless of the number of hypertension-related co-morbidities, but may only be effective in conditions such obesity or stroke when combined with high-intensity co-interventions.


Subject(s)
Blood Pressure Monitoring, Ambulatory , Blood Pressure , Hypertension/diagnosis , Hypertension/therapy , Self Care , Aged , Aged, 80 and over , Female , Humans , Hypertension/epidemiology , Hypertension/physiopathology , Male , Middle Aged , Multimorbidity , Predictive Value of Tests , Prognosis , Randomized Controlled Trials as Topic , Risk Factors , Time Factors
2.
J Fish Biol ; 92(3): 804-827, 2018 Mar.
Article in English | MEDLINE | ID: mdl-29537086

ABSTRACT

Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important challenges raised by these issues have been recognized and have led to considerable advances over past decades in managing and mitigating threats to fishes worldwide. In this review, we identify the major threats faced by fish populations alongside recent advances that are helping to address these issues. There are very significant efforts worldwide directed towards ensuring a sustainable future for the world's fishes and fisheries and those who rely on them. Although considerable challenges remain, by drawing attention to successful mitigation of threats to fish and fisheries we hope to provide the encouragement and direction that will allow these challenges to be overcome in the future.


Subject(s)
Conservation of Natural Resources/methods , Fisheries , Fishes/physiology , Animals , Ecosystem , Fishes/growth & development , Population Dynamics , Water Quality
3.
J Fish Biol ; 92(5): 1255-1272, 2018 May.
Article in English | MEDLINE | ID: mdl-29528118

ABSTRACT

Schooling behaviour in yellow-eyed mullet Aldrichetta forsteri, a common fish species in New Zealand estuarine habitats, was investigated to identify interaction rules associated with group formation. Tank-based three-dimensional studies of three group sizes (15, 75 and 150 individuals) were carried out to measure the effects of these different group sizes on school structure during control, predation risk and foraging behavioural states. Increased group size positively correlated with nearest-neighbour distance in control and foraging states. Swimming speed was the lowest in all three behavioural states in groups of 15 fish compared with 75 or 150. Immediate behavioural response following visual exposure to a simulated avian predator differed between groups resulting in loss of structure in larger groups. School shape was an oblong-oblate spheroid with a length, breadth and height ratio of 5:2:1 and the area of free space surrounding individual fish was spherical in shape with a high degree of spatial isotropy present in all size groups. These findings challenge traditional theories based on either local or global properties as key drivers of group structure. Instead, our results suggest that a more collaborative approach involving both group size and rules pertaining to nearest-neighbour interactions affects collective behaviours in this species.


Subject(s)
Smegmamorpha , Social Behavior , Animal Distribution , Animals , Fishes/physiology , New Zealand , Predatory Behavior , Swimming
4.
Int J STD AIDS ; 23(2): 133-5, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22422689

ABSTRACT

Our management of anogenital warts was audited. By case-note review 95% were clear of original warts by three months (assuming wart clearance if patients stopped attending). However, by confirmed outcome (documented in case-notes or verified by telephone) only 81% were clear. The main reason for failure was inconsistent patient attendance. Subsequently, clinic staff were advised to emphasize the importance of regular treatment. A second audit was performed after 12 months. By case-note review 127/134 (95%) had achieved wart clearance, but by confirmed outcome only 74/89 (83%) were clear (P = 0.004). More men (89%) achieved clearance than women (80%). Again, the main reason for failure was inconsistent attendance. There are few data of outcomes in clinical practice at three months. Auditable outcome measures should be challenging yet achievable. Perhaps 90% clearance at three months is not achievable in clinical practice when allowing for the evidence base and patient choice. Is it time to revise the standard?


Subject(s)
Clinical Audit/methods , Condylomata Acuminata/therapy , Genital Diseases, Female/therapy , Genital Diseases, Male/therapy , Condylomata Acuminata/pathology , Disease Management , Female , Genital Diseases, Female/pathology , Genital Diseases, Male/pathology , Hospital Departments , Humans , Interviews as Topic , Male , Retrospective Studies , Treatment Outcome
5.
J Fish Biol ; 79(7): 1883-94, 2011 Dec.
Article in English | MEDLINE | ID: mdl-22141893

ABSTRACT

Visual acuity of the commercially important sparid Pagrus auratus was tested using the optomotor response. Juvenile fish were categorized by size as group 1 (50 g), group 2 (100 g), group 3 (150 g), group 4 (300 g), group 5 (500 g) and group 6 (800 g). Group 3 fish demonstrated excellent visual acuity (minimum separable angle, M(SA), 1°), which was improved compared with the smaller fish groups (groups 1 and 2, M(SA), 2°). In the larger fish groups, however, a reduction in visual acuity was observed (groups 4, 5 and 6 M(SA), 4°). Group 2 (100 g) fish displayed positive optomotor responses in long wavelength light (red) but reduced responses in short wavelengths (blue). Red light sensitivity is beneficial for the estuarine lifestyle of these fish, where light is predominantly at long wavelengths. In contrast, group 6 (800 g) fish displayed improved acuity in blue and green light and reduced acuity in red light. Fish of this size move away from the estuary to open oceans, where light is predominantly in the shorter wavelengths (blue-green). These results support the sensitivity hypothesis for the relationship between fish visual systems and the light environment they inhabit.


Subject(s)
Body Size/physiology , Light , Perciformes/physiology , Visual Acuity/physiology , Animals , Lens, Crystalline/anatomy & histology , Perciformes/anatomy & histology
6.
J Fish Biol ; 79(1): 280-9, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21722124

ABSTRACT

The rate of velar movement in Eptatretus cirrhatus, as determined by electromyography, increased with Q(10) 3·2 during exposure to temperatures between 7 and 19° C and increased 3·9 fold during exposure to hypoxia (oxygen partial pressure = 6·67 kPa). This confirms the role of the velum in generating respiratory currents and modification of its activity in response to changes in metabolic demand or environmental oxygen availability. The maximum velar rate observed was 168 beats min(-1) , higher than that recorded in any hagfish species to date. Fibres of musculus craniovelaris were exclusively small, red (slow-twitch) fibres, consistent with a high aerobic capacity required by fibres involved in rhythmic, ongoing activity.


Subject(s)
Hagfishes/physiology , Hypoxia , Muscles/physiology , Temperature , Animals , Heart Rate , New Zealand , Oxygen/physiology
7.
J Fish Biol ; 74(3): 535-52, 2009 Feb.
Article in English | MEDLINE | ID: mdl-20735577

ABSTRACT

Extrinsic neural and humoral influences on heart rate (fH) and ventilation frequency (fV) were examined following varying periods of post-surgical recovery in eight related Antarctic fish species inhabiting an array of inshore niches. Resting fH after recovery from handling was lower than previous reports, and the novel measurement of routine fH in free-swimming Dissostichus mawsoni (6.14 beats min(-1), bpm) is the lowest recorded for any fish. The extent of cardio-depressive cholinergic (vagal) tonus explained the large range of fH among species and varied with behavioural repertoire, being lower in the more active species, apart from Notothenia coriiceps. Adrenergic tonus was low compared with cholinergic tonus, with the exception of Trematomus newnesi. Hence, high cardiac cholinergic tonus may be a genotypic trait of the notothenioids that diverged with ecotype. Power spectral analysis showed that the vagal influence produced comparable spectra among species of similar morphology and ecotype. Removal of autonomic tonus resulted in a remarkably similar intrinsic fH between species. Simultaneous measurements of cardio-respiratory variables and oxygen consumption (M(O(2))) were made in the benthic Trematomus bernacchii and cryopelagic Pagothenia borchgrevinki. The slopes of the relationship between fH and M(O(2)) were similar. Trematomus bernacchii, however, had a higher M(O(2)) for a given fH than P. borchgrevinki, and P. borchgrevinki required a two-fold larger range in fH to reach a similar maximum M(O(2)), suggesting that there is a difference in cardiovascular fitness between the two species. Overall, the data suggest that cardio-respiratory control in Antarctic nototheniids is largely determined by activity levels associated with a given ecotype.


Subject(s)
Fishes/physiology , Heart Rate , Oxygen Consumption , Animals , Antarctic Regions , Fishes/anatomy & histology
8.
Chemosphere ; 71(4): 795-801, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18035392

ABSTRACT

Diffusive gradients in thin films (DGT) is a dynamic, in situ measuring technique that can be used to supply diverse information on concentrations and behaviour of solutes. When deployed in soils and sediments, quantitative interpretation of DGT measurements requires the use of a numerical model. An improved version of the DGT induced fluxes in soils and sediments model (DIFS), working in two dimensions (2D DIFS), was used to investigate the accuracy with which DGT measurements can be used to estimate the distribution coefficient for labile metal (KD) and the response time of the soil to depletion (TC). The 2D DIFS model was used to obtain values of KD and TC for Cd, Zn and Ni in three different soils, which were compared to values determined previously using 1D DIFS for these cases. While the 1D model was shown to provide reasonable estimates of KD, the 2D model refined the estimates of the kinetic parameters. Desorption rate constants were shown to be similar for all three metals and lower than previously thought. Calculation of an error function as KD and TC are systematically varied showed the spread of KD and TC values that fit the experimental data equally well. These automatically generated error maps reflected the quality of the data and provided an appraisal of the accuracy of parameter estimation. They showed that in some cases parameter accuracy could be improved by fitting the model to a sub-set of data.


Subject(s)
Models, Chemical , Soil , Diffusion , Reproducibility of Results , Time Factors
9.
Lipids Health Dis ; 6: 30, 2007 Oct 31.
Article in English | MEDLINE | ID: mdl-17973988

ABSTRACT

Postprandial lipaemia may lead to an increase in oxidative stress, inducing endothelial dysfunction. Exercise can slow gastric emptying rates, moderating postprandial lipaemia. The purpose of this study was to determine if moderate exercise, prior to fat ingestion, influences gastrointestinal transit, lipaemia, oxidative stress and arterial wall function. Eight apparently healthy males (age 23.6 +/- 2.8 yrs; height 181.4 +/- 8.1 cm; weight 83.4 +/- 16.2 kg; all data mean +/- SD) participated in the randomised, crossover design, where (i) subjects ingested a high-fat meal alone (control), and (ii) ingested a high-fat meal, preceded by 1 h of moderate exercise. Pulse Wave Velocity (PWV) was examined at baseline, post-exercise, and in the postprandial period. Gastric emptying was measured using the 13C-octanoic acid breath test. Measures of venous blood were obtained prior to and following exercise and at 2, 4 and 6 hours post-ingestion. PWV increased (6.5 +/- 1.9 m/sec) at 2 (8.9 +/- 1.7 m/sec) and 4 hrs (9.0 +/- 1.6 m/sec) post-ingestion in the control group (time x group interaction, P < 0.05). PWV was increased at 2 hrs post-ingestion in the control compared to the exercise trial; 8.9 +/- 1.7 vs. 6.2 +/- 1.5 m/sec (time x group interaction, P < 0.05). Lipid hydroperoxides increased over time (pooled exercise and control data, P < 0.05). Serum triacylglycerols were elevated postprandially (pooled exercise and control data, P < 0.05). There were no changes in gastric emptying, cholesterol, or C-reactive protein levels. These data suggest that acute exercise prior to the consumption of a high-fat meal has the potential to reduce vascular impairments.


Subject(s)
Dietary Fats/metabolism , Endothelium, Vascular/physiology , Exercise/physiology , Gastrointestinal Motility/physiology , Lipids/blood , Oxidative Stress/physiology , Postprandial Period/physiology , Adult , Blood Flow Velocity/physiology , Blood Glucose/metabolism , Blood Pressure/physiology , Cross-Over Studies , Gastric Emptying/physiology , Humans , Male , Oxidative Stress/drug effects , Pain Measurement
10.
J Environ Qual ; 35(5): 1903-13, 2006.
Article in English | MEDLINE | ID: mdl-16973632

ABSTRACT

The theoretical basis for using measurements of metal uptake by the technique of diffusive gradients in thinfilms (DGT) to mimic processes in soils that affect uptake of metals by plants is examined. The uptake of metals by plants and DGT were compared conceptually and quantitatively by using the classic Barber model of plant uptake and the DIFS (DGT-induced fluxes in soils) model of uptake by DGT. For most metals and plants considered, uptake fluxes were similar to those induced by DGT using the most common gel layer thicknesses of 0.2 to 2 mm. Consequently DGT perturbs the chemical equilibrium of metals in the soil solution and between soil solution and solid phase, to a similar extent to plants, and therefore induces a similar balance in supply by diffusion and by release from the solid phase. DIFS was used to show that desorption kinetics, which are not considered by the plant uptake model, are likely important for uptake when the capacity of the soil solid phase is large. Model calculations showed that mass flow into a plant root would only contribute appreciably to the total flux of metal under circumstances when the solid phase reservoir of metal was very low. Generally, however, DGT is likely to emulate supply processes from the soil that govern uptake of metal by plants. Exceptions are likely to be found in poorly buffered soils (typically sandy and/or low pH), and at very high concentrations of metals in soil solution, such that the soil solution concentration at the plant root interface is higher than the Michaelis-Menten constant (Km).


Subject(s)
Metals/metabolism , Models, Biological , Plant Roots/metabolism , Plants/metabolism , Soil , Diffusion , Kinetics
11.
Sci Total Environ ; 357(1-3): 208-20, 2006 Mar 15.
Article in English | MEDLINE | ID: mdl-15936802

ABSTRACT

The insolubility of metal sulphides is believed to limit the bioavailability of trace metals in sulphidic sediments. However, if non-equilibrium conditions are important, metals may be more available than simple thermodynamic calculations suggest. To investigate the possible dynamic supply of Cu, Ni and Zn in a sulphidic freshwater sediment, they were measured, along with iron, manganese and sulphide, by the technique of diffusive gradients in thin-films (DGT). DGT measures the supply of solute from sediment to solution in response to a local solute sink. Release of Mn, Cu, Zn and Ni was observed at the sediment surface and attributed to the supply from reductive dissolution of manganese oxides. The depth profile of simultaneously extractable metals (SEM) for Cu and Ni followed the shape of the Mn profile more closely than the profiles of either acid volatile sulphur (AVS) or Fe, again consistent with supply from Mn oxides. Solubility calculations for a mesocosm of homogenised sediment indicated supersaturation with respect to the sulphides of Fe, Cu, Ni and Zn, yet DGT measurements demonstrated a substantial supply of both trace metals and sulphide from the solid phase to the pore waters. Ratios of metals measured in pore waters by DGT were consistent with their release from iron and manganese oxides, indicating that supply, as much as removal processes, determines the pseudo-steady state concentrations in the pore waters. The observations suggest that trace metals are not immediately bound in an insoluble, inert form when they are in contact with sulphide. This has consequences for modelling metal processes in sediment, as well as for uptake by some biota.


Subject(s)
Chemistry Techniques, Analytical/methods , Geologic Sediments/analysis , Metals, Heavy/analysis , Sulfides/analysis , Water Pollutants, Chemical/analysis , Acrylic Resins/chemistry , Diffusion , Environmental Monitoring/methods , Fresh Water , Geologic Sediments/chemistry , Iodides/chemistry , Kinetics , Metals, Heavy/chemistry , Resins, Synthetic/chemistry , Silver Compounds/chemistry , Sulfides/chemistry
12.
Environ Sci Technol ; 39(6): 1591-7, 2005 Mar 15.
Article in English | MEDLINE | ID: mdl-15819214

ABSTRACT

DGT (diffusive gradients in thin films) was used to measure the distribution and rates of exchange of Zn, Cd, and Ni between solid phase and solution in five different soils. Soil texture ranged from sandy loam to clay, pH ranged from 4.9 to 7.1, and organic carbon content ranged from 0.8% to 5.8%. DGT devices continuously remove metal to a Chelex gel layer after passage through a well-defined diffusion layer. The magnitude of the induced remobilization flux from the solid phase is related to the pool size of labile metal and the exchange kinetics between dissolved and sorbed metal. DGT devices were deployed over a series of times (4 h to 3 weeks), and the DIFS model (DGT induced fluxes in soils) was used to derive distribution coefficients for labile metal (Kdl) and the rate at which the soil system can supply metal from solid phase to solution, expressed as a response time. Response times for Zn and Cd were short generally (<8 min). They were so short in some soils (<1 min) that no distinction could be made between supply of metal being controlled by diffusion or the rate of release. Generally longer response times for Ni (5-20 min) were consistent with its slow desorption. The major factor influencing Kdl for Zn and Cd was pH, but association with humic substances in the solid phase also appeared to be important. The systematic decline, with increasing pH, in both the pool size of Ni available to the DGT device and the rate constant for its release is consistent with a part of the soil Ni pool being unavailable within a time scale of 1-20 min. This kinetic limitation is likely to limit the availability of Ni to plants.


Subject(s)
Cadmium/analysis , Cadmium/chemistry , Nickel/analysis , Nickel/chemistry , Soil Pollutants/analysis , Zinc/analysis , Zinc/chemistry , Diffusion , Environmental Monitoring , Hydrogen-Ion Concentration , Kinetics , Solubility
13.
Article in English | MEDLINE | ID: mdl-15748865

ABSTRACT

Postprandial changes in haemolymph glucose concentration ([Glc]H) were measured in 4-day-fasted juvenile intermoult spiny lobsters, Jasus edwardsii, provided with meals composed of glycogen, maltose, sucrose, glucose, or fructose in a gelatine base, or with gels of the algal glycans agar, alginate and carrageenan. Baseline [Glc]H was 0.61+/-0.02 mmol L(-1). After consumption of glycogen, maltose or sucrose, [Glc]H approximately doubled, peaked after 3 h and returned to baseline between 12 and 24 h. Glucose and fructose meals were followed by periods of sustained hyperglycaemia lasting more than 24 h (peaking at approximately 2.5 times baseline at 6 and 3 h respectively). Suggested explanations for augmented hyperglycaemic responses to glucose and fructose are: 1) these monosaccharides by-passed contact digestion and absorption in the R-cells of the digestive gland, directing them away from storage and toward transepithelial scavenging routes; or 2) glucose and fructose directly elicited release of crustacean hyperglycaemic hormone via a chemosensory reflex. Agar and alginate induced significant postprandial glycaemic responses, consistent with reports of carbohydrases in this species and indicating their potential for inclusion in artificial diets as both binders and energy sources. Carrageenan, a highly sulphated galactan, did not produce a glycaemic response. The measurement of glycaemic responses is a quick method of obtaining nutritional information on carbohydrates considered for inclusion in formulated diets prior to lengthy growth trials.


Subject(s)
Dietary Carbohydrates/metabolism , Glucose/metabolism , Hemolymph/metabolism , Palinuridae/physiology , Agar/metabolism , Alginates/metabolism , Animals , Carrageenan/metabolism , Eating , Eukaryota , Fructose/metabolism , Glycogen/metabolism , Maltose/metabolism , Sucrose/metabolism
14.
Sci Total Environ ; 328(1-3): 275-86, 2004 Jul 26.
Article in English | MEDLINE | ID: mdl-15207590

ABSTRACT

The technique of DGT (Diffusive Gradients in Thin Films) was further developed to allow simultaneous measurement of sulfide and trace metals at the same location in sediment. The new combined DGT probe consisted of a layer of gel impregnated with AgI, overlain by (1) a layer of gel containing Chelex, (2) a layer of gel and (3) a filter membrane. Diffusion of sulfide was controlled by layers (1) to (3), while diffusion of metals was controlled by layers (2) and (3). The Chelex gel trapped metals that were measured after elution with acid. The AgI gel trapped sulfide through the formation of Ag2S. This was then measured densitometrically as the colour changed from pale yellow to grey. Experiments demonstrated that concentrations of metal or sulfide measured by the combined device were no different to the concentrations measured by more conventional devices. The presence of Chelex in the gel did not impede the diffusion of sulfide. Deployment of a combined probe in marine sediment revealed simultaneous remobilisation of metals and sulfide at the same location. Solubility calculations indicated that some precipitation of amorphous FeS was probably occurring at the maxima in sulfide concentrations. There was general undersaturation with respect to NiS, but ZnS was supersaturated at all locations. There appeared to be localised active zones of organic matter decomposition, where reduction of manganese oxides, iron oxides and sulfate occurred simultaneously. Mass balance calculations indicated that Ni could not be supplied by release from decomposing organic matter. Manganese oxides were the most likely source, but supply from reductive dissolution of iron oxides could not be entirely discounted. Supply from either Fe or Mn oxides could account for the Zn maxima. Application of the newly developed combined probe provides new information that helps understanding of the complex nature of trace metal and sulfur chemistry in sediments.


Subject(s)
Chemistry Techniques, Analytical/methods , Environmental Monitoring/methods , Geologic Sediments , Metals, Heavy/analysis , Sulfides/analysis , Chemistry Techniques, Analytical/instrumentation , Densitometry , Environmental Monitoring/instrumentation , Polystyrenes , Polyvinyls , Silver Compounds/chemistry
15.
Anal Bioanal Chem ; 373(8): 873-9, 2002 Apr.
Article in English | MEDLINE | ID: mdl-12194053

ABSTRACT

The techniques of diffusive gradients (DGT) and equilibration (DET) in thin-films have been combined in a single probe that can determine Cr(III) and Cr(VI) simultaneously in solution. The assembly has a layer of polyacrylamide hydrogel overlying a separate layer of resin embedded in gel. Cr(III) species accumulate exclusively and quantitatively in the resin layer, while Cr(VI) species equilibrate with both hydrogel and resin layers. The species are separated by peeling the two layers apart. Chromium is then eluted from each of the two layers. Cr(III) and Cr(VI) were determined quantitatively in standard, mixed solutions by in situ separation with DGT and detection by GF-AAS. With this method, Cr(III) is typically preconcentrated by a factor of 10 over a 24 h deployment, and limits of detection of 8 ng/L Cr(III) and 0.3 micro g/L Cr(VI) were achieved. Due to the inbuilt preconcentration of Cr(III), the technique is particularly good at measuring low concentrations of Cr(III) in the presence of an excess of Cr(VI). Measurements were performed in three soils with various levels of chromium contamination. A concentration of 3 micro g/L of labile Cr(III) was measured reproducibly in the presence of 290 micro g/L of unreactive Cr species and 0.2 micro g/L of labile Cr(III) was measured in the presence of 24 micro g/L of unreactive Cr. The unique feature of the method is that the separation of Cr(III) from Cr(VI) occurs in situ. The Cr species are then stable in the resin and gel prior to analysis, eliminating the artefacts associated with sampling and storage, which are particularly prevalent for redox-sensitive elements. Therefore, it has great potential for assessing Cr(III) and Cr(VI) concentrations in situ in environments near redox boundaries where possible dynamic changes in Cr(III) and Cr(VI) concentrations are occurring.

16.
Environ Sci Technol ; 36(5): 982-8, 2002 Mar 01.
Article in English | MEDLINE | ID: mdl-11924544

ABSTRACT

An isotopic dilution assay was developed to measure radiolabile As concentration in a diverse range of soils (pH 3.30-7.62; % C = 1.00-6.55). Soils amended with 50 mg of As kg(-1) (as Na2HAsO4 x 7H2O) were incubated for over 800 d in an aerated "microcosm" experiment. After 818 d, radiolabile As ranged from 27 to 57% of total applied As and showed a pH-dependent increase above pH 6. The radiolabile assay was also applied to three sets of soils historically contaminated with sewage sludge or mine-spoil. Results reflected the various geochemical forms in which the arsenic was present. On soils from a sewage disposal facility, radiolabile arsenate ranged from 3 to 60% of total As; mean lability was lower than in the equivalent pH range of the microcosm soils, suggesting occlusion of As into calcium phosphate compounds in the sludge-amended soils. In soils from mining areas in the U.K. and Malaysia, radiolabile As accounted for 0.44-19% of total As. The lowest levels of lability were associated with extremely large As concentrations, up to 17,000 mg kg(-1), from arsenopyrite. Soil pore water was extracted from the microcosm experiment and speciated using "GEOCHEM". The solid<==>solution equilibria of As in the microcosm soils was described by a simple model based on competition between HAsO4(2-) and HPO4(2-) for "labile" adsorption sites.


Subject(s)
Arsenic/chemistry , Models, Theoretical , Soil Pollutants , Environmental Monitoring , Forecasting , Isotopes , Mining , Sewage , Solubility
17.
Water Res ; 36(5): 1286-96, 2002 Mar.
Article in English | MEDLINE | ID: mdl-11902783

ABSTRACT

Synthetic solutions that emulate the major ion compositions of natural waters are useful in experiments aimed at understanding biogeochemical processes. Standard recipes exist for preparing synthetic analogues of seawater, with its relatively constant composition, but, due to the diversity of freshwaters, a range of compositions and recipes is required. Generic protocols are developed for preparing synthetic freshwaters of any desired composition. The major problems encountered in preparing hard and soft waters include dissolving sparingly soluble calcium carbonate, ensuring that the ionic components of each concentrated stock solution cannot form an insoluble salt and dealing with the supersaturation of calcium carbonate in many hard waters. For acidic waters the poor solubility of aluminium salts requires attention. These problems are overcome by preparing concentrated stock solutions according to carefully designed reaction paths that were tested using a combination of experiment and equilibrium modeling. These stock solutions must then be added in a prescribed order to prepare a final solution that is brought into equilibrium with the atmosphere. The example calculations for preparing hard, soft and acidic freshwater surrogates with major ion compositions the same as published analyses, are presented in a generalized fashion that should allow preparation of any synthetic freshwater according to its known analysis.


Subject(s)
Calcium Carbonate/chemistry , Environmental Monitoring/methods , Models, Theoretical , Water/chemistry , Aluminum , Hydrogen-Ion Concentration , Kinetics , Solubility
18.
Environ Sci Technol ; 35(12): 2602-7, 2001 Jun 15.
Article in English | MEDLINE | ID: mdl-11432571

ABSTRACT

Risk assessments of metal contaminated soils need to address metal bioavailability. To predict the bioavailability of metals to plants, it is necessary to understand both solution and solid phase supply processes in soils. In striving to find surrogate chemical measurements, scientists have focused either on soil solution chemistry, including free ion activities, or operationally defined fractions of metals. Here we introduce the new concept of effective concentration, CE, which includes both the soil solution concentration and an additional term, expressed as a concentration, that represents metal supplied from the solid phase. CE was measured using the technique of diffusive gradients in thin films (DGT) which, like a plant, locally lowers soil solution concentrations, inducing metal supply from the solid phase, as shown by a dynamic model of the DGT-soil system. Measurements of Cu as CE, soil solution concentration, by EDTA extraction and as free Cu2+ activity in soil solution were made on 29 different soils covering a large range of copper concentrations. Theywere compared to Cu concentrations in the plant material of Lepidium heterophyllum grown on the same soils. Plant concentrations were linearly related and highly correlated with CE but were more scattered and nonlinear with respect to free Cu2+ activity, EDTA extraction, or soil solution concentrations. These results demonstrate that the dominant supply processes in these soils are diffusion and labile metal release, which the DGT-soil system mimics. The quantity CE is shown to have promise as a quantitative measure of the bioavailable metal in soils.


Subject(s)
Copper/pharmacokinetics , Models, Theoretical , Plants , Soil Pollutants/pharmacokinetics , Biological Availability , Copper/analysis , Diffusion , Forecasting , Kinetics , Linear Models , Risk Assessment , Soil Pollutants/analysis , Solubility
19.
J Comp Physiol B ; 171(4): 263-9, 2001 May.
Article in English | MEDLINE | ID: mdl-11409623

ABSTRACT

We examined the burst swimming performance of two Antarctic fishes, Trematomus bernacchii and T. centronotus, at five temperatures between -1 degrees C and 10 degrees C. As Antarctic fishes are considered one of the most cold specialised and stenothermal of all ectotherms, we predicted they would possess a narrow thermal performance breadth for burst swimming and a correlative decrease in performance at high temperatures. Burst swimming was assessed by videotaping swimming sequences with a 50-Hz video camera and analysing the sequences frame-by-frame to determine maximum velocity, the distance moved throughout the initial 200 ms, and the time taken to reach maximum velocity. In contrast to our prediction, we found both species possessed a wide thermal performance breadth for burst swimming. Although maximum swimming velocity for both T. bernacchii and T. centronotus was significantly highest at 6 degrees C, maximum velocity at all other test temperatures was less than 20% lower. Thus, it appears that specialisation to a highly stable and cold environment is not necessarily associated with a narrow thermal performance breadth for burst swimming in Antarctic fish. We also examined the ability of the Antarctic fish Pagothenia borchgrevinki to acclimate their burst-swimming performance to different temperatures. We exposed P. borchgrevinki to either -1 degrees C or 4 degrees C for 4 weeks and tested their burst-swimming performance at four temperatures between -1 degrees C and 10 degrees C. Burst-swimming performance of Pagothenia borchgrevinki was unaffected by exposure to either -1 degrees C or 4 degrees C for 4 weeks. Maximum swimming velocity of both acclimation groups was thermally independent over the total temperature range of 1 degrees C to 10 degrees C. Therefore, the loss of any capacity to restructure the phenotype and an inability to thermally acclimate swimming performance appears to be associated with inhabiting a highly stable thermal environment.


Subject(s)
Cold Temperature , Fishes/physiology , Swimming/physiology , Acclimatization/physiology , Animals , Antarctic Regions , Phenotype , Temperature , Videotape Recording
20.
J Am Psychoanal Assoc ; 49(1): 217-34, 2001.
Article in English | MEDLINE | ID: mdl-11379722

ABSTRACT

From a set of seventeen complete and tape-recorded psychoanalyses, a sample of findings is presented: (a) the level of agreement of two clinical judges on the psychological health of these patients is adequate for the late sessions, but not for the early sessions; (b) the amount of change during psychoanalysis appears to be similar to that in the Menninger Foundation Psychotherapy Research Project; (c) psychiatric severity measures from the early sessions can yield a significant level of prediction of the later benefits from psychoanalysis. Finally, further research uses of this collection of psychoanalyses are suggested.


Subject(s)
Mental Disorders/diagnosis , Mental Disorders/therapy , Psychoanalytic Therapy , Adult , Databases, Factual , Female , Humans , Male , Observer Variation , Psychiatric Status Rating Scales , Retrospective Studies , Treatment Outcome
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