Formation of radioactive waste in Estonian water treatment plants.

In northern Estonia, higher levels of Ra-226 and Ra-228 concentrations give rise to problems with water treatment plants (WTPs) using Cambrian-Vendian (Cm-V) aquifer. During water treatment processes, radionuclides accumulate in the filter material to a level where the material could be classified as a radioactive material. In order to understand the scope of the problem, a nation-wide survey was carried out among the Cm-V fed treatment plants. Filter material and water samples were collected from 18 Estonian WTPs to analyse the activity concentration of Ra-226 and Ra-228 in filter materials and also the radium treatment efficiency was determined. Sixteen WTPs exceeded the exemption levels of 1 kBq * kg-1 set by the EC directive 2013/59/Euratom. The quantity of filter material exceeding the exemption levels was approximately 300 tons, average concentrations values for Ra-226, Ra-228 and Th-228 were, accordingly, 7.6 kBq * kg-1, 8.0 kBq * kg-1 and 5.6 kBq * kg-1. That includes WTPs not designed for radium removal. The results suggest a need to investigate further NORM generation in WTPs, as uncontrollable disposal of NORM may occur.

Direct Observation of the Injection Dynamics of a Laser Wakefield Accelerator Using Few-Femtosecond Shadowgraphy.

We present few-femtosecond shadowgraphic snapshots taken during the nonlinear evolution of the plasma wave in a laser wakefield accelerator with transverse synchronized few-cycle probe pulses. These snapshots can be directly associated with the electron density distribution within the plasma wave and give quantitative information about its size and shape. Our results show that self-injection of electrons into the first plasma-wave period is induced by a lengthening of the first plasma period. Three-dimensional particle-in-cell simulations support our observations.

[HME filter versus patient-related replacement of tubes from the ventilation circuit for anaesthesia: a cost-benefit analysis]. / HME-Filter versus patientenbezogener Wechsel der Beatmungsschlauchsysteme von Narkosegeräten: Eine Kosten-Nutzen-Analyse.

Procedure-related costs were calculated for an operating theatre with 10 operating rooms. The variable parameter was the different hygiene regimens for the preparation of the anaesthesia circuit. In April 2003 a change was made for the whole anaesthesia area. Either change of the anaesthesia tube system after every patient or the use of a hydrophobic HME-F (heat and moisture exchange filter) with daily or weekly change of the anaesthesia tube system were calculated. All costs were ascertained on real findings and typical procedures. Data according to safety and hygienic value were discussed and supplemented by our own findings about perioperative pneumonia. The additional costs for the HME-F are covered by the savings for CO(2) lines and the reduction of reprocessing expenses and overall material costs were reduced. The operational work on anaesthesia machines decreased considerably. Combined cost types revealed savings up to 9,72 EUR for a single anaesthesia procedure. Filtration of the respiratory gases for particles, bacteria, viruses and airway climatisation is an additional positive effect of HME-F use. Incidence of postoperative pneumonia on intensive care units was monitored by KISS (German hospital infection surveillance system) and the change to the HME-F regimen did not indicate a higher risk of infection. By the implementation of a weekly change of the anaesthesia tube system using HME filters a hygienic management for anaesthesia circuit reprocessing was found which could mobilize considerable resources.

[The effects of active and passive humidification on ventilation-associated nosocomial pneumonia]. / Einfluss von aktiver und passiver Befeuchtung auf die beatmungsassoziierte nosokomiale Pneumonie.

STUDY OBJECTIVE: Airway humidification of ventilated patients in an intensive care unit may be established by heated humidifying systems (active) or by the means of a (passive) heat and moisture exchange filter (HMEF). There is a controversial discussion about the influence of the type of humidification on the rate of ventilator-associated pneumonia (VAP). Among 3,585 patients both methods were tested over a period of 21 months in an open, non-randomized cohort study. The aim of the investigation was to compare the incidence of VAP caused by a change of humidification strategy. METHOD: All patients in a 16-bed surgical intensive care unit who required mechanical ventilation, were included. In the first period (period AB) 1,887 cases were handled with a heated humidifier. During the second period (period PB) 1,698 patients were treated using a HMEF. Infection control was established according to the national Infection Surveillance Program (KISS) based on the CDC criteria for VAP. RESULTS: During the period of 42 months, 99 cases of VAP were reported. The incidence for VAP was found to be 13.5 (AB) and 9.6 (PB) per 1,000 ventilator days, a rate of 32.3 and 22.4 VAP per 1,000 patients, respectively. The rate of VAP among the groups ( p=0.068) and the incidence of VAP per 1,000 ventilator days ( p=0.089) only just failed to reach a significant level, but in the group of patients requiring mechanical ventilation for more than 2 days, the difference did reach statistical significance ( p=0.012). CONCLUSION: Our results showed that the rate of VAP could be significantly reduced by changing the strategy from active to passive humidification devices, especially concerning patients requiring long-term respirator therapy. A more physiological humidification and a reduced number of airway manipulations are discussed as a possible explanation.

[A comparison of the Proseal laryngeal mask to the standard laryngeal mask on anesthesized, non-relaxed patients]. / Ein Vergleich der Larynxmaske (LMA) vom Typ Proseal gegen die Standard-LMA bei anästhesierten, nicht relaxierten Patienten. Ergebnisse einer deutschen Multizenterstudie.

It was our goal to compare the Proseal-laryngeal mask airway (PLMA) with the classical laryngeal mask airway (LMA) in a german multicenter trial. Handling of the instruments and application criteria were to be tested. 7 anaesthesia departments were able to take part in this study. 280 patients could be investigated after approval of the ethics committee of the medical faculty of the university of Goettingen. 145 patients received the PLMA and 135 the LMA. The surgical interventions were small to moderate procedures with a duration of at least 20 minutes in the sections general surgery, trauma/orthopedic surgery, urology, vascular surgery, gynecology, ENT-surgery and ophthalmology. There was equivalence of the two instruments PLMA and LMA concerning duration and ease of insertion, endoscopic position check, observations on emergence, potential for injury and some postoperative complaints. This equivalence could be confirmed statistically. Laryngospasm was observed in three, Bronchospasm in two patients with the PLMA, in no one with the LMA. In one case of laryngospasm and another of bronchospasm a mechanism of supraglottic laryngeal stenosis has been involved which may occur in rare instances with the PLMA. This mechanism is due to the double cuff of the PLMA with the instruments proximity to the laryngeal inlet. The seal pressure in both groups differs significantly (p = 0.001). The mean value for the seal pressure was 29,3 +/- 0,21 mbar for the PLMA and 20,9 +/- 0,21 mbar for the LMA. In the PLMA the gastric tube could be positioned with the first attempt in 118 patients, with the second attempt in 17 cases. In 10 patients the gastric tube could not be placed. Contrary to the LMA the tip of the PLMA cuff may be bent in some cases with loss of airway safety and positioning of the gastric tube. The symptoms sore throat and painful swallowing on the first postoperative day were more frequent with LMA application. These differences could be confirmed statistically (sore throat p = 0.01, painful swallowing p = 0.04). They may be explained by the more rigid LMA compared to the PLMA and by the fact that the LMA in this study was older than the PLMA, loosing plasticizer. The drainage tube within the PLMA offers safety from aspiration in patients with no primary aspiration risk, additional reassurance for a correct position and a better stability of the airway. Our data may support a wider indication range for the PLMA compared with the LMA. The PLMA may be applied in laparoscopies and lower abdominal surgical interventions. Careful clinical observation will show, if the minimal invasiveness of the PLMA offers an advantage for these patients. The PLMA should not be applied in patients with increased aspiration risk.