Small understorey trees have greater capacity than canopy trees to adjust hydraulic traits following prolonged experimental drought in a tropical forest.

Future climate change predictions for tropical forests highlight increased frequency and intensity of extreme drought events. However, it remains unclear whether large and small trees have differential strategies to tolerate drought due to the different niches they occupy. The future of tropical forests is ultimately dependent on the capacity of small trees (<10 cm in diameter) to adjust their hydraulic system to tolerate drought. To address this question, we evaluated whether the drought tolerance of neotropical small trees can adjust to experimental water stress and was different from tall trees. We measured multiple drought resistance-related hydraulic traits across nine common neotropical genera at the world's longest-running tropical forest throughfall-exclusion experiment and compared their responses with surviving large canopy trees. Small understorey trees in both the control and the throughfall-exclusion treatment had lower minimum stomatal conductance and maximum hydraulic leaf-specific conductivity relative to large trees of the same genera, as well as a greater hydraulic safety margin (HSM), percentage loss of conductivity and embolism resistance, demonstrating that they occupy a distinct hydraulic niche. Surprisingly, in response to the drought treatment, small trees increased specific hydraulic conductivity by 56.3% and leaf:sapwood area ratio by 45.6%. The greater HSM of small understorey trees relative to large canopy trees likely enabled them to adjust other aspects of their hydraulic systems to increase hydraulic conductivity and take advantage of increases in light availability in the understorey resulting from the drought-induced mortality of canopy trees. Our results demonstrate that differences in hydraulic strategies between small understorey and large canopy trees drive hydraulic niche segregation. Small understorey trees can adjust their hydraulic systems in response to changes in water and light availability, indicating that natural regeneration of tropical forests following long-term drought may be possible.

Additional value of triple-sensor urethral catheter in demonstrating urethral pressure variations during filling cystometry.

AIMS: During filling cystometry, urethral pressure variations (UPV) can be observed. The clinical relevance and a clear definition of this phenomenon are still a matter of debate. For further research and definition of UPV, it is important to determine how this condition can best be demonstrated. The purpose of this study is to compare continuous urethral pressure measurements with a single urethral-sensor catheter and a triple urethral-sensor catheter in demonstrating UPV. METHODS: Seventy-five adult female patients requiring urodynamic investigation enrolled in this prospective study. All patients underwent two series of filling and voiding cystometry. One series was performed with a dual-air balloon sensor urodynamic catheter, the other series with a triple urethral-sensor catheter. UPV were defined as urethral pressure drop exceeding 30 cmH2O. RESULTS: The prevalence of UPV was 37.3% (28 out of 75 patients), more common than detrusor overactivity. The triple urethral-sensor catheter was more sensitive than the single urethral-sensor catheter: In eight patients UPV were demonstrated with both catheters and in 18 patients only in the measurement with the triple urethral-sensor catheter. This difference in detection was significant (P < .001). CONCLUSION: There is an additional value in measurement with the triple urethral-sensor catheter for demonstration of UPV during filling cystometry. Currently, continuous measurement of urethral pressure during filling cystometry and UPV is not defined within International Continence Society terminology. The single urethral-sensor catheter is useful for a start, however, it demonstrates less than half of all UPV.

Urethral instability: current pathophysiological concept.

The role of urethral pressure variations during filling cystometry is seldom assessed as a potential cause of voiding dysfunction and/or storage disorders. In this article, we review current research in the field of urethral pressure variations and discuss the way of determining urethral pressure variations, its value for the clinical practice and hypothesize the origin of urethral pressure variations. The observation and recognition of urethral pressure variations (urethral instability) could be valuable in the diagnosis and evaluation of therapy in functional lower urinary tract disorders.

Description of nine nutrient loss models: capabilities and suitability based on their characteristics.

In EUROHARP, an EC Framework V project, which started in 2002 with 21 partners in 17 countries across Europe, a detailed intercomparison of contemporary catchment-scale modelling approaches was undertaken to characterise the relative importance of point and diffuse pollution of nutrients in surface freshwater systems. The study focused on the scientific evaluation of different modelling approaches, which were validated on three core catchments (the Ouse, UK; the Vansjo-Hobøl, Norway; and the Enza, Italy), and the application of each tool to three additional, randomly chosen catchments across Europe. The tools involved differ profoundly in their complexity, level of process representation and data requirements. The tools include simple loading models, statistical, conceptual and empirical model approaches, and physics-based (mechanistic) models. The results of a scientific intercomparison of the characteristics of these different model approaches are described. This includes an analysis of potential strengths and weaknesses of the nutrient models.

Subannual models for catchment management: evaluating model performance on three European catchments.

Models' abilities to predict nutrient losses at subannual timesteps is highly significant for evaluating policy measures, as it enables trends and the frequency of exceedance of water quality thresholds to be predicted. Subannual predictions also permit assessments of seasonality in nutrient concentrations, which are necessary to determine susceptibility to eutrophic conditions and the impact of management practices on water quality. Predictions of subannual concentrations are pertinent to EC Directives, whereas load estimates are relevant to the 50% target reduction in nutrient loading to the maritime area under OSPAR. This article considers the ability of four models (ranging from conceptual to fully mechanistic), to predict river flows, concentrations and loads of nitrogen and phosphorus on a subannual basis in catchments in Norway, England, and Italy. Results demonstrate that model performance deemed satisfactory on an annual basis may conceal considerable divergence in performance when scrutinised on a weekly or monthly basis. In most cases the four models performed satisfactorily, and mismatches between measurements and model predictions were primarily ascribed to the limitations in input data (soils in the Norwegian catchment; weather in the Italian catchment). However, results identified limitations in model conceptualisation associated with the damping and lagging effect of a large lake leading to contrasts in model performance upstream and downstream of this feature in the Norwegian catchment. For SWAT applied to the Norwegian catchment, although flow predictions were reasonable, the large number of parameters requiring identification, and the lack of familiarity with this environment, led to poor predictions of river nutrient concentrations.

Evaluation of the difference of eight model applications to assess diffuse annual nutrient losses from agricultural land.

The capability of eight nutrient models to predict annual nutrient losses (nitrogen and phosphorus) at catchment scale have been studied in the EUROHARP project. The methodologies involved in these models differ profoundly in their complexity, level of process representation and data requirements. This evaluation is focused on model performance in three core catchments: the Vansjø-Hobøl (Norway), the Ouse (Yorkshire, UK) and the Enza (Italy). These three different model applications have been evaluated by comparing calculated annual nutrient loads (total N or nitrate and total P), based on observed flow and total nitrogen or nitrate and total phosphorus concentrations, and the annual nutrient loads that were simulated by the eight nutrient models. Four statistics have been applied for this purpose: the root mean squared error (RMSE), the mean absolute error (MAE), the mean error (ME), and Nash-Sutcliffe's model efficiency (NS). The results show that all model approaches can predict the calculated annual discharges. Depending on the observed statistics (RMSE, MAE, ME and NS) the scores of the model application differed, therefore no overall 'best model' could be identified. Although the water and nutrient loads from (sub)catchments can be predicted, the modelled pathways of nutrients within agricultural land and the nutrient losses to surface waters from agricultural land vary among the catchments and among those model approaches which are able to make this distinction.

Evaluation of diffuse pollution model applications in EUROHARP catchments with limited data.

The application of diffuse pollution models included in EUROHARP encompassed varying levels of parameterisation and approaches to the preparation of input data depending on the model and modelling team involved. Modellers consistently faced important decisions in relation to data interpretation, especially in those catchments with unfamiliar physical or climatic characteristics, where catchment conditions were beyond the range for which a particular model was originally developed, or where only limited input data were available. In addition to a broad discussion of data issues, this paper compares the performance of the four sub-annual output models tested in EUROHARP (EveNFlow, NL-CAT, SWAT and TRK) in three test catchments without the modelling teams having sight of measured flow and nitrate concentration data. Model performance in this "blind test" indicate that the range of predictions generated by any individual models pre and post calibration exceed the differences between the estimates yielded by all four models. Comparison of Analysis of Variance (ANOVA) statistics for simulated and observed flow, concentration and loads underscores the benefits of calibration for these intermediate and complex model formulations. Interpretation of input data (e.g. rainfall interpolation method and pedotransfer functions selected) appeared equally (or more) important than process representation. In the absence of calibration data, modeller unfamiliarity with a particular catchment and its environmental processes sometimes resulted in questionable assumptions and input errors which highlight the problems facing modellers charged with implementing policies under the Water Framework Directive (2000/60/EC) in poorly monitored catchments. Catchment data owners and modellers must therefore work more closely given that the output from diffuse pollution models is clearly modeller-limited as well as model-limited.

Ensemble modelling of nutrient loads and nutrient load partitioning in 17 European catchments.

An ensemble of nutrient models was applied in 17 European catchments to analyse the variation that appears after simulation of net nutrient loads and partitioning of nutrient loads at catchment scale. Eight models for N and five models for P were applied in three core catchments covering European-wide gradients in climate, topography, soil types and land use (Vansjø-Hobøl (Norway), Ouse (Yorkshire, UK) and Enza (Italy)). Moreover, each of the models was applied in 3-14 other EUROHARP catchments in order to inter-compare the outcome of the nutrient load partitioning at a wider European scale. The results of the nutrient load partitioning show a variation in the computed average annual nitrogen and phosphorus loss from agricultural land within the 17 catchments between 19.1-34.6 kg N ha(-1) and 0.12-1.67 kg P ha(-1). All the applied nutrient models show that the catchment specific variation (range and standard deviation) in the model results is lowest when simulating the net nutrient load and becomes increasingly higher for simulation of the gross nutrient loss from agricultural land and highest for the simulations of the gross nutrient loss from other diffuse sources in the core catchments. The average coefficient of variation for the model simulations of gross P loss from agricultural land is nearly twice as high (67%) as for the model simulations of gross N loss from agricultural land (40%). The variation involved in model simulations of net nutrient load and gross nutrient losses in European catchments was due to regional factors and the presence or absence of large lakes within the catchment.

Nitrogen and phosphorus retention in surface waters: an inter-comparison of predictions by catchment models of different complexity.

Nitrogen and phosphorus retention estimates in streams and standing water bodies were compared for four European catchments by a series of catchment-scale modelling tools of different complexity, ranging from a simple, equilibrium input-output type to dynamic, physical-based models: source apportionment, MONERIS, EveNFlow, TRK, SWAT, and NL-CAT. The four catchments represent diverse climate, hydrology, and nutrient loads from diffuse and point sources in Norway, the UK, Italy, and the Czech Republic. The models' retention values varied largely, with tendencies towards higher scatters for phosphorus than for nitrogen, and for catchments with lakes (Vansjø-Hobøl, Zelivka) compared to mostly or entirely lakeless catchments (Ouse or Enza, respectively). A comparison of retention values with the size of nutrient sources showed that the modelled nutrient export from diffuse sources was directly proportional to retention estimates, hence implying that the uncertainty in quantification of diffuse catchment sources of nutrients was also related to the uncertainty in nutrient retention determination. This study demonstrates that realistic modelling of nutrient export from large catchments is very difficult without a certain level of measured data. In particular, even complex process oriented models require information on the retention capabilities of water bodies within the receiving surface water system and on the nutrient export from micro-catchments representing the major types of diffuse sources to surface waters.

Comparative study of model prediction of diffuse nutrient losses in response to changes in agricultural practices.

This article presents a comparative study of modelled changes in nutrient losses from two European catchments caused by modifications in agricultural practices. The purpose was not to compare the actual models used, but rather to assess the uncertainties a manager may be faced with after receiving decision support from consultants using different models. Seven modelling teams were given the same data about two catchments and their management characteristics and were asked to model the same changes in management practices using the model of their own choice. This can potentially cause accumulated 'errors' due to differences in the modelling teams' interpretation of relevant processes and definitions of boundary conditions (inputs). The study was carried out within the framework of the EUROHARP project, which aimed at harmonising procedures for quantifying diffuse losses of nitrogen and phosphorus from agriculture. Models are important for assessing river basin management plans (RBMPs) as required e.g. under the EC Water Framework Directive and Action Plans under the EC Nitrates Directive. This article illustrates some challenges with respect to interpreting such modelling results. The selected management scenarios include changes in fertiliser application levels, changes in livestock numbers and changes in land-use and crop rotation systems. Seven models were applied for the same scenarios in the Enza catchment in Italy and the Zelivka catchment in the Czech Republic. All models had been calibrated and validated with respect to historical data of climatic conditions, water quality and discharge measurements. The modelling results reveal a variation in predicted effects of the management scenarios, causing different conclusions with respect to choice of best management practice for reducing nutrient losses. The study demonstrates that it is important that care is taken by modellers and involved decision makers throughout the entire modelling process, both with regard to a common understanding of the problem definition, understanding of boundary conditions, and uncertainty of outputs and interpretation of results.

Extracorporeal magnetic innervation therapy: assessment of clinical efficacy in relation to urodynamic parameters.

OBJECTIVE: Clinical efficacy and urodynamic changes in women treated by extracorporeal magnetic innervation therapy (ExMI) were studied. MATERIAL AND METHODS: Women, presenting with urge, stress and mixed urinary incontinence, were included in a prospective study. ExMI was applied by an electromagnetic chair. To document clinical efficacy, a voiding diary and visual analogue scale were completed before and after treatment, together with a pad test. Detrusor overactivity (DO) and urethral instability (URI) were urodynamically documented. Clinical success was defined as more than 50% improvement in symptoms. RESULTS: Sixteen patients were included. At baseline, DO was observed in 10 patients, and URI in 12 patients. DO did disappear at follow-up in 60%, and a decrease in URI was seen in 66%. No significant clinical improvement was seen at follow-up. CONCLUSION: Although significant changes in urodynamic variables were observed, no significant improvement in clinical efficacy was seen after ExMI.

Uncertainty analysis at large scales: limitations and subjectivity of current practices--a water quality case study.

Uncertainty analysis for large-scale model studies is a challenging activity that requires a different approach to uncertainty analysis at a smaller scale. However, in river basin studies, the practice of uncertainty analysis at a large scale is mostly derived from practice at a small scale. The limitations and inherent subjectivity of some current practices and assumptions are identified, based on the results of a quantitative uncertainty analysis exploring the effects of input data and parameter uncertainty on surface water nutrient concentration. We show that: (i) although the results from small- scale sensitivity analysis are often applied at larger scales, this is not always valid; (ii) the current restriction of the uncertainty assessment to uncertainty types with a strong evidence base gives structurally conservative estimates; (iii) uncertainty due to bias is usually not assessed, but it may easily outweigh the effects of variability; (iv) the uncertainty bandwidth may increase for higher aggregation levels, although the opposite is the standard assumption.

Urethral instability and sacral nerve stimulation-a better parameter to predict efficacy?

PURPOSE: Urodynamic parameters that predict the outcome of sacral nerve stimulation are difficult to define. We studied the predictive value of urethral instability and other urodynamic parameters on the efficacy of sacral nerve stimulation. MATERIALS AND METHODS: Patients with refractory voiding disorders were implanted with a neurostimulator after responding with more than 50% improvement in main symptoms after percutaneous nerve evaluation. Filling cystometry was performed with 3 urethral sensors and 1 bladder sensor at baseline and 6 months after implantation. Urethral pressure variations more than 15 cm H(2)O were considered pathological and defined as urethral instability. Clinical efficacy was evaluated by voiding diary data and defined as successful when greater than 50% improvement was observed. RESULTS: A total of 19 female patients enrolled in the study. At baseline detrusor overactivity was observed in 9 patients, while 18 showed urethral instability. Sacral nerve stimulation therapy was successful in 13 patients (68%). The number of pads used per day and the severity of leakage decreased significantly. Of the 13 successfully treated patients 12 showed urethral instability at baseline. Detrusor overactivity was present in 4 successfully treated patients. Urethral instability disappeared in 7 of the 13 successfully treated patients and detrusor overactivity disappeared in only 1 of these patients. CONCLUSIONS: In this study urethral instability appeared to be a valuable urodynamic parameter for predicting the outcome of sacral nerve stimulation.

Functional extracorporeal magnetic stimulation as a treatment for female urinary incontinence: 'the chair'.

OBJECTIVE: To evaluate, in a prospective study, the efficiency and applicability of functional magnetic stimulation (FMS) of the pelvic floor for treating urinary incontinence in women. PATIENTS AND METHODS: FMS was provided by a 'magnetic chair'; 24 patients were treated twice weekly for 8 weeks (12 with urge incontinence and 12 with a mixture of urge and stress incontinence). The outcome was assessed urodynamically, by a pad test, and by patient satisfaction. RESULTS: In 58% of the patients there was an objective improvement in incontinence; three patients were completely dry and 71% reported a subjective improvement (P < 0.001). CONCLUSION: FMS is a safe, noninvasive and painless treatment for urinary incontinence; it is effective and easy to administer as an outpatient treatment.

The plication procedure for penile curvature: surgical outcome and postoperative sexual functioning.

OBJECTIVE: This study evaluates the patients' judgement of the surgical outcome of the plication procedure, as described by Schröder and Essed, and the postoperative sexual functioning of patients with congenital curvatures and Peyronie's disease. PATIENTS AND METHODS: Of 98 patients treated for penile curvatures between 1985 and 1996, 85 patients received postoperatively a 'Questionnaire Assessing the Outcome of Surgery' and a short version of the 'Questionnaire for Screening Sexual Dysfunctions'. RESULTS: 28 patients with congenital curvatures and 31 with Peyronie's disease were evaluated. 75% of the patients with congenital curvatures and 58% of the patients with Peyronie's disease were satisfied with the result. Patients treated for Peyronie's disease reported diminished penile length and inability to have sexual intercourse more often than patients with congenital curvatures (90 vs. 64%, and 29 vs. 0%). After correction for age, patients with Peyronie's disease were less satisfied with their present sex life, had more frequent erectile problems and more trouble with considerable sexual desire than a group of 42 controls. For patients with Peyronie's disease satisfaction with the result was positively correlated with satisfaction with their present sex life and negatively correlated with the frequency of erectile problems. For patients with congenital curvatures satisfaction with the result was negatively correlated with both a postoperative curvature and a repeat operation. CONCLUSIONS: Some patients with Peyronie's disease may not benefit from surgical correction (alone). Because of the occurrence of sexual problems, future evaluation of the role of pre- and postoperative sexological counselling in achieving better results is recommended.

Development of the inlet portion of the right ventricle in the embryonic rat heart: the basis for tricuspid valve development.

BACKGROUND: Before septation the entire atrioventricular canal is connected with the ventricular inlet segment (primitive left ventricle) whereas the mature heart exhibits an exclusive connection of the right atrium to the right ventricle. The process which is responsible for this change is controversial. METHODS: Graphic reconstructions of serially sectioned embryonic rat hearts as well as scanning electron micrographs of similar specimens were made. RESULTS: The first indication of a right atrioventricular connection was seen as a groove in the atrioventricular junctional myocardium to the right of the inferior endocardial cushion. This groove expanded to form the right ventricular inlet portion. The right, inferior, and superior walls of this newly formed cavity were formed from junctional myocardium, which demarcated it from the trabeculated right ventricular portion in all developmental stages. The left wall equally developed from this junctional myocardium and formed the ventricular inlet septum. The junctional myocardium between right ventricular inlet and trabeculated portions was seen to develop into the tricuspid valve and its tension apparatus. CONCLUSIONS: The preseptation embryonic heart has no inlet portion to the right ventricle. This new cavity is created by remodelling of atrioventricular junctional myocardium. This myocardium also provides the material contribution to the tricuspid valve and its tension apparatus. Malformations of the right ventricular inlet portion and of the tricuspid valve are indissolubly linked.