Zur Interpretation der Dosiswirkungsbeziehungen in der Strahlenbiologie

Der Zufallscharakter zellulärer Strahleneffekte muß nicht stets auf einer Variabilität der Strahlenempfindlichkeit oder auf einer inhomogenen Verteilung der absorbierten Energie auf die Einheiten einer bestrahlten Population oder ihre ldquorTreffbereicheldquo beruhen, sondern kann auch bei einer kontinuierlich mit der Dosis zunehmenden ldquordispersen Vorschädigungldquoaller Einheiten zustandekommen, wenn diese die inhärente Labilität des lebenden Systems erhöht. Das zufallsartige ldquorkritische Ereignisldquo, das über das Eintreten der Testreaktion entscheidet, muß daher nicht unbedingt schon durch die Energieabsorption gegeben sein, sondern kann in einem späteren Glied der Ursachenkette liegen. Charakteristisch für den Verlauf von Überlebenskurven ist ihre Neigung in halblogarithmischer Darstellung; wir bezeichnen diese Größe als ldquorReaktivitätldquo. Kurvenformen, die bisher durch den Mehrtreffer- oder Mehrbereichsansatz gedeutet wurden, ergeben sich auch, wenn man allein die Tatsache berücksichtigt, daß die Reaktivität mit der Dosis ansteigen kann. Strebt die Reaktivität mit steigender Dosis einem Endwert zu, so kann dies darauf beruhen, daß eine dem vitalen Objekt inhärente Kompensationsfähigkeit sich mit der Dosis erschöpft. In einigen Fällen wird die biochemische Natur einer solchen Kompensationsfähigkeit bereits deutlich

Advantages and disadvantages of different nasal CPAP systems in newborns

Objective: To compare three different systems of continuous positive airway pressure (CPAP): the naso-pharyngeal tube and two-prong systems in newborns, focusing on duration of CPAP, side effects and cost. Design: Randomized clinical study. Patients: Between July 2000 and September 2001 newborns were randomized to three different CPAP systems. Forty infants in two weight groups (>2500g and 1250-2500g; 20 patients in each group) were included. Results: In the group >2500g the median duration of CPAP was 1.1days (range 0.25-14.3days). The median time on a naso-pharyngeal CPAP was 1day (range 0.25-14.3days), on Hudson prongs 1.6days (range 0.5-3.3days) and on the Infant Flow system 0.7days (range 0.3-13.6days; p>0.05 for comparison between groups, Fisher's exact test). With naso-pharyngeal CPAP, 2 patients developed moderate nasal injuries. On Hudson, 2 patients developed moderate and three mild nasal injuries. One patient on the Infant Flow showed mild and one moderate nasal injuries. In the weight group 1250-2500g the median duration of CPAP was 1.1days (range 0.1-7.0days). The median time on the naso-pharyngeal tube was 0.9days (range 0.1-7days), on Hudson prongs 1.1days (range 0.7-6.6days) and on the Infant Flow system 1.3days (range 0.25-5.9days; p>0.05 for comparison between groups, Fisher's exact test). With a naso-pharygeal tube, one infant developed mild and one moderate nasal injuries. On Hudson prongs, two had moderate nasal injuries. On Infant Flow, one newborn showed a severe nasal injury and two mild injuries. None of the patients developed a pneumothorax. Conclusion: The naso-pharyngeal tube is an easy, safe and economical CPAP system usable with every common ventilator. For very low birth weight newborns, a prong system may have advantage

Thermal preference of adult mosquitoes (Culicidae) and biting midges (Ceratopogonidae) at different altitudes in Switzerland

Mosquitoes (Diptera: Culicidae) and biting midges (Diptera: Ceratopogonidae) are among the most important vectors of human and veterinary pathogens. For modelling the distribution of these pathogens, entomological aspects are essential, which in turn are highly dependent on environmental factors, such as temperature. In this study, mosquitoes and biting midges were sampled in multiple microclimates at two low (360, 480 meters above sea level, m.a.s.l.) and two high (1250, 1530 m.a.s.l.) altitude locations in Switzerland. Sets of various traps (CO2 -baited CDC, LED-UV, resting boxes, oviposition cups) equipped with dataloggers were placed in transects at five sites with similar vegetation at each location. Only the CDC and the LED-UV traps collected enough insects for analyses. Taxonomic diversity was greater for mosquitoes but lower for biting midges at lower altitudes. Both mosquitoes and biting midges had a thermal preference. Culicoides preferred the traps with warmer microclimate, especially at lower altitudes, whereas mosquito preferences depended on the species, but not on altitude. Relative humidity had a significant positive impact on catches of biting midges but not mosquitoes. To obtain better data on thermal preferences of resting and ovipositing vectors in addition to host seeking individuals, new and improved collecting methods are needed

Peer review and citation data in predicting university rankings, a large-scale analysis

Most Performance-based Research Funding Systems (PRFS) draw on peer review and bibliometric indicators, two different method- ologies which are sometimes combined. A common argument against the use of indicators in such research evaluation exercises is their low corre- lation at the article level with peer review judgments. In this study, we analyse 191,000 papers from 154 higher education institutes which were peer reviewed in a national research evaluation exercise. We combine these data with 6.95 million citations to the original papers. We show that when citation-based indicators are applied at the institutional or departmental level, rather than at the level of individual papers, surpris- ingly large correlations with peer review judgments can be observed, up to r <= 0.802, n = 37, p < 0.001 for some disciplines. In our evaluation of ranking prediction performance based on citation data, we show we can reduce the mean rank prediction error by 25% compared to previous work. This suggests that citation-based indicators are sufficiently aligned with peer review results at the institutional level to be used to lessen the overall burden of peer review on national evaluation exercises leading to considerable cost savings

Lab Scale Fixed-Bed Reactor for Operando X-Ray Absorption Spectroscopy for Structure Activity Studies of Supported Metal Oxide Catalysts

Lab scale fixed-bed reactor is applied for operando transmission X-ray absorption spectroscopy (XAS) for structure-activity studies of supported metal oxide catalysts under real reaction conditions. This setup includes many properties of an optimal fixed-bed reactor for operando transmission XAS studies. For instance, it is usable in a wide range of temperature (up to 1,000°C), pressure and space velocity. Besides, this operando setup can be used for transmission XAS measurements in a wide edge energy range. The potential of this reactor for operando transmission XAS is demonstrated by, as examples, the three-way catalytic performance of Pd/Al2O3/CeZrO2 and Rh/Al2O

Partial Grid Forming Concept for 100% Inverter-Based Transmission Systems

With the current trends in renewable energy integration, the concept of a 100% inverter-based power system is becoming more of a reality. However, the existing Voltage Source Converter (VSC) control schemes for such systems focus mostly on the operation of low-voltage microgrids, which have different requirements from the transmission system perspective. This paper proposes a new classification of VSC control strategies depending on their mode of operation. Then, the concept of partial grid forming VSC is introduced and it is shown that a system with zero rotational inertia can operate without a dedicated grid-forming VSC unit, but rather with partial forming of key system characteristics distributed across different VSC units. The performance of this approach is tested on detailed VSC models developed in both MATLAB Simulink and virtual Hardware-In-the-Loop (vHIL) platforms. Furthermore, an investigation towards necessary converter and network criteria for providing a stable system under the proposed control concepts is presented