Quantitative prediction of microbial growth calculated from time-temperature profiles: Practical examples for Salmonella Typhimurium growth in cooked ground beef

The preservation of food safety requires risk analyses and the implementation of preventive measures, as well as the availability of quantitative criteria to help the decision process. Up until now, the main difficulty was to quantify the microbial growth in foodstuffs. This article presents criteria used to calculate the bacterial growth potential, based on predictive microbiology models. In combination with a microbial expert’s report, these criteria predict growth based on time-temperature profiles of a given food. Two practical examples, including a description of the method of calculation, are also given.L'analyse des dangers et la mise en place de mesures de prévention sont des démarches nécessaires à la maîtrise de la sécurité sanitaire. Pour ce faire, des critères quantitatifs sont à rechercher en vue d'aider à la décision. Jusqu'à présent, le principal obstacle résidait dans la difficulté à quantifier la croissance microbienne dans les denrées. Sur les bases de la microbiologie prévisionnelle, des critères de calcul du potentiel de croissance sont présentés. Associés à l'expertise microbiologique ils permettent de prédire cette croissance à partir des profils temps-température associés à un aliment. Deux exemples pratiques, dont l'un détaille le mode de calcul, sont donnés en complément

Radiotherapy of choroidal metastases.

Abstract Purpose: This retrospective study was undertaken to clarify the role of high energy external beam radiation therapy (EBRT) and to determine its safety and efficacy on local control and visual acuity in patients suffering from choroidal metastases (CM). Materials and methods: The records of 58 consecutive patients treated with EBRT between 1970 and 1993 were analyzed. The female to male ratio was 2.9 and the median age was 59 years (range 40–81 years). Thirty-six patients (62%) had unilateral CM and 22 patients had bilateral CM. The mean number of lesions per eye was two. Retinal detachment was present in 65% of cases. The primary tumour (PT) was breast carcinoma for 38 patients (75%), lung carcinoma for 10 patients (17%) and gastrointestinal, genitourinary or unknown PT for the remaining 10 patients. The median interval of time between the PT and the CM was 55 months (range 0–228 months). All patients were treated with megavoltage irradiation. The median prescribed dose was 35.5 Gy (range 20–53 Gy) normalized at a 2 Gy per fraction schedule with an a/b value of 10 Gy. Various techniques were used and whenever possible the lens was spared. Ten patients with unilateral disease were treated in both eyes. Results: The tumour response was slow. When assessed after 3 months or more, the complete response rate was 53% with significantly better results for doses higher than 35.5 Gy (72 versus 33%; P = 0.009). Visual acuity was improved or stabilized in 62% of patients, with also significantly better results when doses higher than 35.5 Gy (P = 0.014) were administered. Amongst 26 patients with unilateral CM who had no elective contralateral irradiation, three developed metastasis in the opposite eye versus none of the 10 patients who had bilateral irradiation. Five complications occurred (three cataracts, one retinopathy and one glaucoma). Conclusion: Radiation therapy is an efficient and safe palliative treatment for choroidal metastases and it helps the preservation of vision. Thus, there is a major impact on the quality of life in a group of patients with an almost uniformly fatal prognosis. Both tumour response and visual acuity are significantly improved if doses higher than 35.5 Gy are administered. Whenever possible, a lens sparing technique should be used. Ó 1998 Elsevier Science Ireland Ltd

Azores seismogenic zones

One condition to perform seismic hazard analysis is knowledge about seismogenic zones that is an invaluable source of information and play an important role because it is fundamental know the processes and properties that control the seismogenic zone. The aim of this work is distinguishing seismogenic zones in the Azores region applying different parameters such as the earthquake density, b-values, focal mechanism, historical seismicity and all of these conjugated within the geodynamic framework of the Azores. We identified 10 seismogenic zones plus the well known Mid Atlantic Ridge. The 10 zones we identified are over the major tectonic structures of the Archipelago, namely Terceira Rift and Linear Volcanic Ridges

Ion-implanted compliant and patternable electrodes for miniaturized dielectric elastomer actuators

This article presents metal ion implantation as an alternative technique to fabricate compliant electrodes for small-size dielectric elastomer actuators. When reducing the size of these actuators to below 1 cm, the ability to pattern the electrodes is added to the need for compliance. Metal ion implantation on Polydimethylsiloxane (PDMS) layers allows the creation of conductive and compliant electrodes, which can be easily defined by photolithography or with a shadow mask. Mechanical testing show that implantation has a limited impact on the PDMS' properties, with a Young's modulus increase of 50%-200% depending on the dose. Uniaxial stretching tests show that conductivity is conserved for strains up to 50% and present no hysteresis. Dielectric breakdown tests were conducted for Au and Pd implantations, which exhibited high breakdown fields (>100 V/um), similar to non-implanted PDMS layers. Other advantages of ion implanted electrodes include transparency and a negligible mass. Buckling mode diaphragm actuators were fabricated with ion-implanted electrodes and exhibited out-of-plane displacements up to 7% of their lateral dimensions

Performance characterization of miniaturized dielectric elastomer actuators fabricated using metal ion implantation

We report measurements of displacement and mechanical work for miniaturized Dielectric Elastomer Actuators (DEAs) whose compliant electrodes were fabricated using metal ion implantation. 20 to 30 μm thick Polydimethylsiloxane (PDMS) membranes were bonded to silicon chips with through holes of diameter 2 to 3 mm and were implanted on both sides with gold ions. Out-of-plane deflection recorded as a function of voltage and applied mechanical distributed load was in very good agreement with an analytical model. Unloaded vertical displacements up to 7% of the membrane's diameter were recorded and mechanical work up to 0.3 μJ was obtained with an applied pressure of 1 kPa. This performance data and associated model allow such miniaturized polymer actuators to be efficiently dimensioned for different applications, for instance in micropumps and active optical devices

[Decision process in oncology: the importance of multidisciplinary meeting]

International audienceMultidisciplinary meeting (MDM) in oncology has been institutionalised in France by the Cancer Plan. This study aims to determine the place of MDM in the decision process. From November 2004 to July 2005, we observed 29 meetings at the Tours Hospital and 324 case presentations, 80 in orthopaedics, 151 in gastroenterology and 93 in chest medicine. Forty physicians attending the meetings answered a questionnaire exploring their opinions on MDM and the collegial decision. We found that MDM is mostly the place for technical discussions and that patients' wishes are rarely addressed. The different medical specialities are well represented but we observed that only physicians attend MDM. Decisions for straightforward cases are rapidly validated. For more complex clinical situations (25 to 40% of case presentations), the multidisciplinary approach allows to adapt guidelines or to choose alternative treatments. All the physicians interviewed express that MDM legitimates the medical decision. It occurs that they disagree with the RCP decision. We discuss how MDM impacts on the medical decision as well as the shift from the individual decision to the collective one, particularly in term of responsibility

Mechanical properties of electroactive polymer microactuators with ion-implanted electrodes

We report on the use of the bulge test method to characterize the mechanical properties of miniaturized buckling mode dielectric elastomer actuators (DEA). Our actuator consists of a Polydimethylsiloxane (PDMS) membrane bonded to a silicon chip with through holes. Compliant electrodes are fabricated on both sides of the membrane by metal ion implantation. The membrane buckles when a critical voltage is applied to the electrodes. The maximum displacements as well as the efficiency of such actuators strongly depend on the mechanical parameters of the combined electrode-elastomer-electrode layer, mainly effective Young's modulus E and residual stress S. We report measured E and S obtained from bulge tests on PDMS membranes for two PDMS brands and for several different curing methods, which allows tuning the residual stress by controlling the rate of solvent evaporation. Bulge test measurements were then used to study the change in membranes' mechanical properties due to titanium ion implantation, compared to the properties obtained from depositing an 8 nm thick gold electrode. At the doses required to create a conductive layer, we find that the Ti ion implantation has a low impact on the membrane's overall rigidity (doubling of the Young's modulus and reducing the tensile stress) compared to the Au film (400% increase in E). The ion implantation method is an excellent candidate for DEAs' electrodes, which need to be compliant in order to achieve large displacements