Laser-irradiating infrared attenuated total reflection spectroscopy of articular cartilage: Potential and challenges for diagnosing osteoarthritis.

Objective: A prototype infrared attenuated total reflection (IR-ATR) laser spectroscopic system designed for in vivo classification of human cartilage tissue according to its histological health status during arthroscopic surgery is presented. Prior to real-world in vivo applications, this so-called osteoarthritis (OA) scanner has been tested at in vitro conditions revealing the challenges associated with complex sample matrices and the accordingly obtained sparse spectral datasets. Methods: In vitro studies on human knee cartilage samples at different contact pressures (i.e., 0.2-0.5 â€‹MPa) allowed recording cartilage degeneration characteristic IR signatures comparable to in vivo conditions with high temporal resolution. Afterwards, the cartilage samples were assessed based on the clinically acknowledged osteoarthritis cartilage histopathology assessment (OARSI) system and correlated with the obtained sparse IR data. Results: Amide and carbohydrate signal behavior was observed to be almost identical between the obtained sparse IR data and previously measured FTIR data used for sparse partial least squares discriminant analysis (SPLSDA) to identify the spectral regions relevant to cartilage condition. Contact pressures between 0.3 and 0.4 â€‹MPa seem to provide the best sparse IR spectra for cylindrical (d â€‹= â€‹3 â€‹mm) probe tips. Conclusion: Laser-irradiating IR-ATR spectroscopy is a promising analytical technique for future arthroscopic applications to differentiate healthy and osteoarthritic cartilage tissue. However, this study also revealed that the flexible connection between the laser-based analyzer and the arthroscopic ATR-probe via IR-transparent fiberoptic cables may affect the robustness of the obtained IR data and requires further improvements.

Spin-1 Hopfield model under a random field.

The goal of the present work is to investigate the role of trivial disorder and nontrivial disorder in the three-state Hopfield model under a Gaussian random field. In order to control the nontrivial disorder, the Hebb interaction is used. This provides a way to control the system frustration by means of the parameter a=p/N, varying from trivial randomness to a highly frustrated regime, in the thermodynamic limit. We performed the thermodynamic analysis using the one-step replica-symmetry-breaking mean field theory to obtain the order parameters and phase diagrams for several strengths of a, the anisotropy constant, and the random field.

Attributiveness of a mass flow analysis model for integrated water resources assessment under data-scarce conditions.

Nutrients in river systems originate from multiple emission sources, follow various pathways, and are subject to processes of conversion and fate. One approach to tackle this complexity is to apply balance-oriented models. Although these models operate on a coarse temporal and spatial scale, they are capable of assessing the significance of the different emission sources and their results can be the basis for developing integrated water quality management schemes. In this paper we propose and apply a methodology to evaluate the attributiveness of such model results with regard to the modelled emission pathways. The MONERIS (MOdelling Nutrient Emissions in RIver Systems) model is set up, assuming plausible ranges of emission levels from four principal sources. The sensitivity of model performance is computed and related to the contribution from the pathways. The approach is applied for a case study in the upper Western Bug catchment (Ukraine). Coefficient of determination (R(2)) is found insensitive against the model assumptions, at levels around 0.65 for nitrogen and 0.55 for phosphorous emissions. Relative mean absolute error is minimized around 0.2 for both nutrients, but with equifinal combinations of the varied emission pathways. Model performance is constrained by the ranges of the emission assumptions to a limited extent only.

An adaptive framework to differentiate receiving water quality impacts on a multi-scale level.

The paradigm shift in recent years towards sustainable and coherent water resources management on a river basin scale has changed the subject of investigations to a multi-scale problem representing a great challenge for all actors participating in the management process. In this regard, planning engineers often face an inherent conflict to provide reliable decision support for complex questions with a minimum of effort. This trend inevitably increases the risk to base decisions upon uncertain and unverified conclusions. This paper proposes an adaptive framework for integral planning that combines several concepts (flow balancing, water quality monitoring, process modelling, multi-objective assessment) to systematically evaluate management strategies for water quality improvement. As key element, an S/P matrix is introduced to structure the differentiation of relevant 'pressures' in affected regions, i.e. 'spatial units', which helps in handling complexity. The framework is applied to a small, but typical, catchment in Flanders, Belgium. The application to the real-life case shows: (1) the proposed approach is adaptive, covers problems of different spatial and temporal scale, efficiently reduces complexity and finally leads to a transparent solution; and (2) water quality and emission-based performance evaluation must be done jointly as an emission-based performance improvement does not necessarily lead to an improved water quality status, and an assessment solely focusing on water quality criteria may mask non-compliance with emission-based standards. Recommendations derived from the theoretical analysis have been put into practice.

IWRM decision support with material flow analysis: consideration of urban system input.

A review of material flow analysis (MFA) tools, comparison of case studies and analysis of approximately 20 MFA tools (static, semi-empirical models) are performed. The evaluation of the quantification procedures revealed several deficits in the approaches. The following principal complications for a reliable quantification of inputs from the urban water system are identified: (1) frequently insufficient data for urban system model validation (e.g. combined sewer overflow (CSO) discharges); (2) the necessity for additionally quantifying diffuse sources in order to verify modelling results at basin scale, where both input pathways occur, and (3) the contradictions arising when describing the highly dynamic urban system with the help of static MFA models. However, a wise selection of appropriate calculation procedures with regard to the concrete systems characteristics and available data can minimize the model deviations significantly. Criteria and suggestions for designing adapted quantification procedures are given.

Element patterns for particulate matter in stormwater effluent.

Particulate matter in stormwater deteriorates the quality of receiving water and sediment. Characterization of stormwater particulate matter by means of its particle-associated element pattern provides an aid to determining its impact on receiving surface waters. During a 6 month measurement campaign, we determined particle-associated concentrations of major pollutants and rare earths for three combined water/stormwater outlets in the town of Stassfurt. We differentiated the particle-associated constituents on the basis of a hierarchical cluster analysis. Repeating the cluster analysis on random subsets, we gained information about the variability of the element patterns between and within the sites. In general, constituents associated with sewage and sewer sediment behave differently compared with constituents associated with runoff. The degree to which associations can be established for element patterns from site to site is limited by the variability encountered within sample sets taken from individual sites. The latter variability depends on the complexity of the catchment.

Extreme value statistics for river quality simulations.

Various methods have been proposed to assess intermittent pollution loads and impacts on rivers in urban areas. Although the variables to describe the impact are mainly the same, the standards show significant differences in the assessment of permitted concentration level, duration and return period. The probability of an event is derived using either frequencies of occurrence or predefined extreme value distributions. Both methods have drawbacks. To bypass these, an a posteriori estimation of the statistical distribution of data based on the peak-over-threshold method is proposed. The method is exemplarily demonstrated using a semi-virtual case study.

Model-based comparison of two ways to enhance WWTP capacity under stormwater conditions.

Two different approaches to increase the fraction of combined water treated in the wastewater treatment plant (WWTP) which would otherwise contribute to combined sewer overflows (CSO) are presented and compared based on modelling results with regard to their efficiencies during various rain events. The first option is to generally increase the WWTP inflow according to its actual capacity rather than pre-setting a maximum that applies to worst case loading. In the second option the WWTP inflow is also increased, however, the extra inflow of combined water is bypassing the activated sludge tank and directly discharged to the secondary clarifier. Both approaches have their advantages. For the simulated time series with various rain events, the reduction of total COD load from CSOs and WWTP effluent discharged to the receiving water was up to 20% for both approaches. The total ammonia load reduction was between 6% for the bypass and 11% for inflow increase. A combination of both approaches minimises the adverse effects and the overall emission to the receiving water.

Modelling of enhanced CSO treatment in secondary clarifiers with a modified Activated Sludge Model no. 3.

An alternative approach for combined water treatment as opposed to its CSO discharge into receiving water is its bypass to the inlet of secondary clarifiers (SC). To analyse the processes and to evaluate the performance of this approach, experiments and numerical modelling were carried out. In batch and pilot scale experiments major effects were identified and quantified. The Activated Sludge Model No. 3 (ASM3) was modified to simulate the batch and pilot scale experiments for implementation of the bypass-specific processes and thus to set up an overall balance of the relevant compounds. With some modifications of ASM3, good agreement of the modelling results with measurements of COD, nitrogen and phosphorus were achieved.

Towards a better understanding of sewer exfiltration.

This paper gives a full review of the importance of sewer leakage, which has received increased attention throughout the last decades. Despite the intensive interdisciplinary research that has been invested, its magnitude is still unclear and a comprehensive solution for the assessment of sewer exfiltration does not seem to be at hand. However, given that mechanisms of exfiltration and the factors influencing its extent are similar all over the world, it seems possible to develop a generic leakage approach. Several methods for modelling sewer leakage are reviewed and the available measuring techniques are critically evaluated. Based on this evaluation, we suggest a unifying framework to facilitate focused model building. Specifically, we identify open research questions and propose to (i) standardise measurement results to enable better understanding, (ii) perform more long-term experiments under realistic field conditions, and (iii) assess the uncertainty of measurement and model results so that findings are not over-interpreted.

Dynamic optimisation of WWTP inflow to reduce total emission.

A prerequisite for an integrated control of sewer and wastewater treatment plant (WWTP) is a capacity driven inflow control to WWTP. This requires reliable information about the current status of WWTP operation and its behaviour on varying hydraulic, COD and nutrient loads. So far most of the proposed control strategies are based on hypothetical modelling studies. In this paper the behaviour of three large WWTPs on increased storm water loads is analysed based on online measurements of several years. In all cases the main limiting factors for an increase of load were the sedimentation processes in the secondary clarifier and the nitrification capacity. In one case study predictive control strategies have been developed observing these processes which are backboned by effluent control. Tests using an integrated model of sewer and WWTP demonstrate that inflow control on emission load varies significantly with rain intensity.

Quantification of sewer leakage: a review.

One of the goals of the APUSS project (assessing infiltration and exfiltration on the performance of urban sewer systems) is to assess sewer exfiltration, in order to support cities and operators to define problem-oriented rehabilitation strategies. In this paper, we review various methods currently used for the estimation of exfiltration and discuss data needs and applicability for rehabilitation planning. Although each approach has its individual advantages and drawbacks, we identified pressure tests and tracer methods to have the highest potential for decision support in rehabilitation planning. With regard to future challenges (e.g., micropollutants) such methods might play a key role in integrated sewer management.

Statistical methods towards more efficient infiltration measurements.

A comprehensive knowledge about the infiltration situation in a catchment is required for operation and maintenance. Due to the high expenditures, an optimisation of necessary measurement campaigns is essential. Methods based on multivariate statistics were developed to improve the information yield of measurements by identifying appropriate gauge locations. The methods have a high degree of freedom against data needs. They were successfully tested on real and artificial data. For suitable catchments, it is estimated that the optimisation potential amounts up to 30% accuracy improvement compared to nonoptimised gauge distributions. Beside this, a correlation between independent reach parameters and dependent infiltration rates could be identified, which is not dominated by the groundwater head.

One-photon photodetachment of I- in glycerol: spectra and yield of solvated electrons in the temperature range 329

Solvated electrons in glycerol were generated via a resonant one-photon photodetachment of the charge-transfer-to-solvent (CTTS) band of I- in glycerol (Gl) after irradiation with a 248 nm excimer laser. Optical absorption spectra of solvated electrons (esolv-) in Gl were recorded as a function of temperature (381

Identification of overall degradation in sewer systems from long-term measurements and consequences for WWTP simulations.

In-sewer transformation processes affect significantly design and operation of large wastewater treatment plants. Especially for long-term simulations the degradation has to be considered in order to avoid over- and underestimation. In this paper a method is presented to derive the overall degradation from available operation data. The application of the results in a long-term simulation of a WWTP shows the relevance of the degradation for design and operation of an activated sludge plant.

Dynamics of rain-induced pollutographs of solubles in sewers.

When looking at acute receiving water impacts due to combined sewer overflows the characteristics of the background diurnal sewage flux variation may influence the peak loads from combined sewer overflows (CSO) and wastewater treatment plant (WWTP) effluent significantly. In this paper, effects on the dynamic compounds transported in the sewer, on CSO discharges and WWTP loading are evaluated by means of hydrodynamic simulations. The simulations are based on different scenarios for diurnal dry-weather flow variations induced by different infiltration rates.

Integrated operation of sewer system and WWTP by simulation-based control of the WWTP inflow.

In recent years numerical modelling became a standard procedure to optimise urban wastewater systems design and operation by integration. For dynamic control of the wastewater teatment plant (WWTP) inflow, a model-based predictive concept is introduced aiming at improving the receiving water quality. An on-line simulator running parallel to the real WWTP operation reflects the actual state of operation and provides this model information to a prognosis tool which determines the best option for the WWTP inflow. The investigations showed that it is possible to reduce the NH4-N peak concentrations in the receiving water by dynamic WWTP inflow control based on predictive scenario analysis.

Integrated modelling for the evaluation of infiltration effects.

The objective of the present study is the estimation of the potential benefits of sewer pipe rehabilitation for the performance of the drainage system and the wastewater treatment plant (WWTP) as well as for the receiving water quality. The relation of sewer system status and the infiltration rate is assessed based on statistical analysis of 470 km of CCTV (Closed Circuit Television) inspected sewers of the city of Dresden. The potential reduction of infiltration rates and the consequent performance improvements of the urban wastewater system are simulated as a function of rehabilitation activities in the network. The integrated model is applied to an artificial system with input from a real sewer network. In this paper, the general design of the integrated model and its data requirements are presented. For an exemplary study, the consequences of the simulations are discussed with respect to the prioritisation of rehabilitation activities in the network.

Application of a leakage model to assess exfiltration from sewers.

The exfiltration of wastewater from sewer systems in urban areas causes a deterioration of soil and possibly groundwater quality. Beside the simulation of transport and degradation processes in the unsaturated zone and in the aquifer the analysis of the potential impact requires the estimation of quantity and temporal variation of wastewater exfiltration. Exfiltration can be assessed by the application of a leakage model. The hydrological approach was originally developed to simulate the interactions between the groundwater and surface water, it was adapted to allow for modelling of interactions between groundwater and sewer system. In order to approximate the exfiltration specific model parameters infiltration specific parameters were used as a basis. Scenario analysis of the exfiltration in the City of Dresden from 1997 to 1999 and during the flood event in August 2002 shows the variation and the extent of exfiltration rates.

ArcEGMO-URBAN--hydrological model for point sources in river basins.

The new model ArcEGMO-URBAN aims at deterministic and spatiotemporal modelling of water, nitrogen and phosphorus fluxes from all urbanised areas of a river basin considering all potential sources. Pollution loads are calculated for discrete urban patches and balanced on the level of hydrological subbasins. Modelling results can be defined by the user of any level of spatial and/or temporal aggregation, e.g. matter balances for river basins or river sections and years or months, respectively. To process spatial data, a Geographic Information System is linked to the model. Information on urban land use and general characteristics of river basins is based on digital coverages, partly generated from remote-sensing data. Moreover, statistical data, e.g. on population, sewer systems, wastewater treatment plants etc. are included. Stormwater runoff from impervious surfaces is calculated as one input to the sewer network. Wastewater is considered with its main sewer system, pumping stations and treatment plants. Finally, the discharge is balanced for discrete river sections. Modelling results attest ArcEGMO-URBAN its ability to realistically quantify matter fluxes and major pollution sources as well as their seasonal variation. This makes the model an applicable tool for the analysis of scenarios with e.g. varying population distribution or climatic and technological conditions.