Retention of mouth-to-mouth, mouth-to-mask and mouth-to-face shield ventilation

Background: Retention of mouth-to-mouth, mouth-to-mask and mouth-to-face shield ventilation techniques is poorly understood.Methods: A prospective randomised clinical trial was undertaken in January 2004 in 70 candidates randomly assigned to training in mouth-to-mouth, mouth-to-mask or mouth-to-face shield ventilation. Each candidate was trained for 10 min, after which tidal volume, respiratory rate, minute volume, peak airway pressure and the presence or absence of stomach inflation were measured. 58 subjects were reassessed 1 year later and study parameters were recorded again. Data were analysed with ANOVA, \textgreekq2 and McNemar tests.Results: Tidal volume, minute volume, peak airway pressure, ventilation rate and stomach inflation rate increased significantly at reassessment with all ventilation techniques compared with the initial assessment. However, at reassessment, mean (SD) tidal volume (960 (446) vs 1008 (366) vs 1402 (302) ml; p<0.05), minute volume (12 (5) vs 13 (7) vs 18 (3) l/min; p<0.05), peak airway pressure (14 (8) vs 17 (13) vs 25 (8) cm H2O; p<0.05) and stomach inflation rate (63% vs 58% vs 100%; p<0.05) were significantly lower with mouth-to-mask and mouth-to-face shield ventilation than with mouth-to-mouth ventilation. The ventilation rate at reassessment did not differ significantly between the ventilation techniques.Conclusions: One year after a single episode of ventilation training, lay persons tended to hyperventilate; however, the degree of hyperventilation and resulting stomach inflation were lower when a mouth-to-mask or a face shield device was employed. Regular training is therefore required to retain ventilation skills; retention of skills may be better with ventilation devices

Shade-induced reduction of stem nonstructural carbohydrates increases xylem vulnerability to embolism and impedes hydraulic recovery in Populus nigra

Nonstructural carbohydrates (NSCs) have been suggested to affect xylem transport under fluctuating water availability, but conclusive evidence is still lacking. We tested the effect of shade-induced NSC depletion on xylem vulnerability to embolism and hydraulic recovery on Populus nigra saplings. Vulnerability was assessed in light-exposed (L) and shaded (S) plants with the hydraulic method, and in vivo with the optical method and X-ray micro-computed tomography. Plants were stressed to 80% loss of hydraulic conductance (PLC) and re-irrigated to check for possible recovery. We measured PLC, bark and wood NSC content, as well as xylem sap pH, surface tension (\u3b3sap) and sugar concentration, before, during and after drought. Shading induced depletion of stem NSC (mainly starch) reserves. All methods converged in indicating higher xylem vulnerability in S than in L plants. This difference was not explained by xylem vessel and pit anatomy or by \u3b3sap. Shading impeded sap acidification and sugar accumulation during drought in S plants and prevented hydraulic recovery, which was observed in L plants. Our results highlight the importance of stem NSCs to sustain xylem hydraulic functioning during drought and suggest that light and/or adequate stem NSC thresholds are required to trigger xylem sap chemical changes involved in embolism recovery

Begleitforschung Solarthermie 2000. Entwicklung eines standardisierten Abnahmeverfahrens fuer solarthermische Grossanlagen Abschlussbericht

First, a simple and efficient tool for projecting solar thermal power systems was to be developed by ITW Stuttgart (see separate ITW Stuttgart report). Parallel to this, a fast and simple method was to be developed for in-situ assessment or the annual yield of such systems, with a maximum error of 5 percent. The following steps were taken: 1. Development of a measuring system for the task; 2. Selection of methods of evaluation for the dynamic in situ short-term test; 3. Development and testing of the method in several industrial-scale systems and validation by comparison with the results of conventional measurements. The dynamic in situ short-term test method developed on this basis consists of six steps which are described in the report. The measuring accuracy depends on the correct function of the plantZunaechst sollte fuer solarthermische Grossanlagen ein Katalog standardisierter Anlagenkonfigurationen erstellt und anschliessend in die gaengigen Planungswerkzeuge TRNSYS und TSOL uebertragen werden, um Planern ein einfaches und leistungsfaehiges Werkzeug zur Auslegung und zur Berechnung des GSR zur Verfuegung zu stellen. Damit sollen Planungsfehler aufgrund fehlender Erfahrung mit Solaranlagen vermieden und ein Standard fuer innovative Anlagenkonzepte verbreitet werden. Dieser Arbeitspunkt wurde ausschliesslich durch das ITW Stuttgart bearbeitet, siehe separater Berichtsteil des ITW Stuttgart. Parallel dazu war ein Testverfahren zu entwickeln, mit dem der Jahresertrag grosser thermischer Solaranlagen in situ, d.h. an der installierten Anlage vor Ort, ohne Eingriff in die Anlage, um die Gewaehrleistungspflicht des Anlagenbauers zu erhalten, auf 5% genau, um ein klares juristisches Kriterium fuer die Feststellung einer etwaigen Nachbesserungspflicht des Erbauers zu haben, kostenguenstig und in kurzer Zeit (maximal 6 Wochen) bestimmt werden kann. Hierzu waren folgende Arbeiten notwendig: 1. Entwicklung einer an die Aufgabenstellung angepassten Messtechnik. 2. Ermittlung geeigneter Auswerteverfahren fuer den dynamischen in situ Kurzzeittest. 3. Entwicklung und Erprobung des Verfahrens an mehreren Grossanlagen u.a. aus dem Programm Solarthermie 2000 und Validierung gegen die Ergebnisse konventioneller Messverfahren. Das entwickelte dynamische in situ Kurzzeit-Testverfahren (ISTT-Verfahren) besteht aus sechs Schritten, die im Beitrag dargestellt werden. Grundvoraussetzung, wie fuer jedes Verfahren zur Abnahmemessung, ist ein ordnungsgemaesser Zustand der Anlage, d.h. dass grobe Anlagenmaengel (z.B. Ventile, Pumpen falsch eingebaut, zu geringer Vordruck im Solarkreis etc.) behoben sein muessen. Zwar werden bei der Anwendung des ISTT-Verfahrens in einem nullten Schritt bei einer Funktionskontrolle Anlagenfehler zuverlaessig detektiert und lokalisiert. (orig./AKF)SIGLEAvailable from TIB Hannover: F01B160 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany); Bundesministerium fuer Wirtschaft und Technologie (BMWi), Berlin (Germany)DEGerman