Biomedical subjects

A Liénard

Publications and source records attributed to A Liénard.

7 recordsLinked to original sources

PubMed2006

Factors that influence cancer patients' anxiety following a medical consultation: impact of a communication skills training programme for physicians.

BACKGROUND: No study has yet assessed the impact of physicians' skills acquisition after a communication skills training programme on the evolution of patients' anxiety following a medical consultation. This study aimed to compare the impact, on patients' anxiety, of a basic communication skills training programme (BT) and the same programme consolidated by consolidation workshops (CW), and to investigate physicians' communication variables associated with patients' anxiety. PATIENTS AND METHODS: Physicians, after attending the BT, were randomly assigned to CW or to a waiting list. The control group was not a non-intervention group. Consultations with a cancer patient were recorded. Patients' anxiety was assessed with the State Trait Anxiety Inventory before and after a consultation. Communication skills were analysed according to the Cancer Research Campaign Workshop Evaluation Manual. RESULTS: No statistically significant change over time and between groups was observed. Mixed-effects modelling showed that a decrease in patients' anxiety was linked with screening questions (P = 0.045), physicians' satisfaction about support given (P = 0.004) and with patients' distress (P < 0.001). An increase in anxiety was linked with breaking bad news (P = 0.050) and with supportive skills (P = 0.013). No impact of the training programme was observed. CONCLUSIONS: This study shows the influence of some communication skills on the evolution of patients' anxiety. Physicians should be aware of these influences.

Adult↗

PubMed2006

Effect of reeds and feeding operations on hydraulic behaviour of vertical flow constructed wetlands under hydraulic overloads.

Vertical flow constructed wetlands (VFCWs) have been very successful in France over the last 5 years. The sizing of VFCWs is still roughly based on organic load acceptance with slight clear water intrusion into the sewerage system which is often wrong in the context of small communities. To specify the hydraulic limits would be of great help to Water Authorities in deciding at what point is it preferable to build separate sewers rather than adapt the wastewater treatment plant. The study of the hydraulic limits of reed beds, based on the knowledge of hydrodynamics in unsaturated porous media, shows the ability of the system to accept flow overloads. Measuring different parameters (flow, pollutant removal, infiltration rate (IR), pressure head profiles) in pilot and full-scale studies, we explain the hydraulic behaviour of the filter, and the role of reeds and batch frequency on the IRs. Consequently, new hydraulic limits with accompanying sizing rules and operational recommendations according to the level of deposit on the filter surface are suggested. The study shows the robustness of reed beds systems as designed in France to accept hydraulic overloads. Overloads up to ten times the dry weather flow are possible whilst still complying with the European standards.

Biodegradation, Environmental↗

PubMed2005

Apatite as an interesting seed to remove phosphorus from wastewater in constructed wetlands.

Intensive use of phosphates has resulted in high P levels in surface waters and therefore eutrophication problems. Over the last decade many studies have revealed the advantage of using specific materials with efficient phosphorus retention capacities. Recent studies state that Ca materials are of particular interest for long-term retention of P, but can induce negative effects. To improve P retention and avoid negative counter-effects we tested the potential of natural apatites. Apatite sorption was evaluated using batch and open reactor experiments. Batch experiments identify sorption mechanisms and the influence of the ionic characteristics of the solution; open reactor experiments evaluate sorption capacities in relation to the ionic composition of the solution and biomass development. In parallel, observation of the material by electron microscopy was used to give more precision information about the mechanisms involved. This work reveals the strong chemical affinity between apatites and phosphorus. Compared to other calcareous materials apatite is better able to maintain low outlet P levels. After more than 550 days feeding, sorption was still present and low P outlet levels were still being obtained when sufficient contact time and calcium content in the solution were ensured. This work demonstrates the advantages of using apatites for phosphorus removal in constructed wetlands. The behaviour of apatite in phosphorus retention is explained and its suitability for use in such extensive systems defined.

Adsorption↗

PubMed2003

Phosphorus retention in subsurface constructed wetlands: investigations focused on calcareous materials and their chemical reactions.

Phosphorus removal from wastewater has been of growing interest for some decades to avoid eutrophication in surface water. In subsurface constructed wetlands precipitation and adsorption are the main mechanisms responsible for P uptake. Two media (calcite and recycled crushed concrete (RCC)) were examined in batch and continuous systems. Batch experiments show attractive sorption capacities, however experiments carried out in open reactors pointed out some limitation in retention capacities and effluent quality. RCC is sensitive to a strong dissolution leading to a quick phosphorus precipitation but induces high conductivity and pH values in the treated water. Calcite efficiency depends on the carbonate equilibrium of the solution. Microscopic observations of the calcite surface show crystal growth of phosphorus precipitate. Crystallisation seems to be the main P uptake once a material's surface is covered.

Adsorption↗

PubMed2002

Use of recycling through medium size granular filters to treat small food processing industry effluents.

Currently there are no suitable wastewater treatment systems for effluents from small food processing industries (dairy, cheese, wine production). Such raw sewages are characterized by high organic matter concentrations (about 10 g COD L-1) and relatively low daily volumes (about 2 m3). An adaptation of attached-growth cultures on fine media processes, known to be easy and inexpensive to use, could fit both the technical and economical context of those industries. Coarser filter particle size distributions than those normally used allow a better aeration and reduce clogging risk. The transit time of the effluent through the porous filter materials is shortened and requires recycling to increase the contact time between the biomass and the substrate. A pilot plant was built to compare the efficiency of two kinds of filter materials, gravel (2-5 mm) and pozzolana (3-7 mm). Two measurement campaigns were undertaken on a full-scale unit dealing with cheese dairy effluents. Both pilot-scale and full-scale plants show high COD removal rates (> 95%). Pilot-scale experiments show that accumulation of organic matter leads to the clogging of the recycling filter. To prevent early clogging, a better definition of feeding cycles is needed.

Conservation of Natural Resources↗

PubMed2002

Modelling of a recirculating granular medium filter's processes.

The effluents of French small farm factories will soon be submitted to regulation. Only a few treatment techniques are available to deal with these kind of effluent (high concentration and small daily volumes). To allow the treatment, in the particular economic context of small food processing industries, Cemagref is trying to adapt a treatment based on attached growth cultures on fine media, a system known to be easy to operate and relatively inexpensive. A model, based on four sub-models (hydrodynamic characteristics, oxygen transport, solute transport in the mobile and immobile phases and bacterial evolution) describes this process. Based on wastewater concentration, hydraulic load, applied organic loads, feeding/rest cycles and recycling phases number, this model predicts: eliminated organic loads and the discharge concentration as a function of time, oxygen and biomass contents as a function of time and depth. The determination of the model's parameters is based on a comparison between simulations and performances achieved on experimental columns. This model would be helpful in sizing full-scale filters treating different types of agro-food wastewater. The aim of this article is to present the model's structure, to give all parameter values and to compare the simulations with the results obtained on pilot and full scale plants.

Agriculture↗

PubMed2001

Choice of the sand for sand filters used for secondary treatment of wastewater.

In a range from 100 to about 1,000 People Equivalent (PE), Secondary Wastewater Sand Filters (SWSF) are used by a lot of rural communities in France. A series of case studies however point out that several criteria concerning global and detailed design and implementation of these systems have to be approached scientifically, in order to obtain the expected results on a long-term basis. The choice of the sand constituting the infiltration bed, core of the biological reactor, is of course one of the key elements and is the main subject of this article. It must have a sufficient initial permeability in order to ensure an adapted infiltration speed, after colonisation by the purifying biomass. The d10 fines content and degree of uniformity mainly control this permeability. The quarry or the aggregate extractor, who masters his production this way, usually gives these elements, based on granulometric analysis. However the adjustment of an infiltration test with clear water is essential to check on site the conformity of the deliveries.

Biomass↗