Studies supporting an upper-atmosphere chemical release program. Part I - Experimental studies on chemiluminescence. Part II - A model of releases leading to upper-atmospheric chemi-ion formation Final report, May 1965 - May 1966

Chemiluminescence of chemical compounds released in upper atmosphere and model of releases leading to upper atmospheric chemi-ionizatio

Characterization of a spark ignition system for flameholding cavities

This paper presents an experimental investigation of a capacitive-discharge spark ignition system designed to promote ignition in CH- and CH-fuelled supersonic combustors. The purpose of this study is the characterization of the ignition system and the plasma generated in the discharge. Schlieren and luminescence imaging are used to visualize the temporal evolution of the spark plasma. Transient voltages and currents across the primary-side of the ignition coil and input-side of the ignition unit are recorded using a high-speed data acquisition system. Three different ignition coils are tested with two different spark plug gaps in an attempt to increase the performance of the ignition system which is evaluated through spatially and temporally integrated luminescence recordings as well as temporally integrated photo diode signals. The data suggests that an increase in performance of a factor of 4-5 over the baseline setup can be achieved. A capacitive ignition lead is used to assess whether or not any capacitance on the coil secondary side can increase the performance of the ignition system. The experiments have also shown that the ignition system parameters can be set to cause sufficient heating of the electrodes to support ignition from a combined glow-spark plug setup

4D Imaging and Diffraction Dynamics of Single-Particle Phase Transition in Heterogeneous Ensembles

In this Letter, we introduce conical-scanning dark-field imaging in four-dimensional (4D) ultrafast electron microscopy to visualize single-particle dynamics of a polycrystalline ensemble undergoing phase transitions. Specifically, the ultrafast metal–insulator phase transition of vanadium dioxide is induced using laser excitation and followed by taking electron-pulsed, time-resolved images and diffraction patterns. The single-particle selectivity is achieved by identifying the origin of all constituent Bragg spots on Debye–Scherrer rings from the ensemble. Orientation mapping and dynamic scattering simulation of the electron diffraction patterns in the monoclinic and tetragonal phase during the transition confirm the observed behavior of Bragg spots change with time. We found that the threshold temperature for phase recovery increases with increasing particle sizes and we quantified the observation through a theoretical model developed for single-particle phase transitions. The reported methodology of conical scanning, orientation mapping in 4D imaging promises to be powerful for heterogeneous ensemble, as it enables imaging and diffraction at a given time with a full archive of structural information for each particle, for example, size, morphology, and orientation while minimizing radiation damage to the specimen

Current issues in medically assisted reproduction and genetics in Europe: research, clinical practice, ethics, legal issues and policy. European Society of Human Genetics and European Society of Human Reproduction and Embryology.

In March 2005, a group of experts from the European Society of Human Genetics and European Society of Human Reproduction and Embryology met to discuss the interface between genetics and assisted reproductive technology (ART), and published an extended background paper, recommendations and two Editorials. Seven years later, in March 2012, a follow-up interdisciplinary workshop was held, involving representatives of both professional societies, including experts from the European Union Eurogentest2 Coordination Action Project. The main goal of this meeting was to discuss developments at the interface between clinical genetics and ARTs. As more genetic causes of reproductive failure are now recognised and an increasing number of patients undergo testing of their genome before conception, either in regular health care or in the context of direct-to-consumer testing, the need for genetic counselling and preimplantation genetic diagnosis (PGD) may increase. Preimplantation genetic screening (PGS) thus far does not have evidence from randomised clinical trials to substantiate that the technique is both effective and efficient. Whole-genome sequencing may create greater challenges both in the technological and interpretational domains, and requires further reflection about the ethics of genetic testing in ART and PGD/PGS. Diagnostic laboratories should be reporting their results according to internationally accepted accreditation standards (International Standards Organisation - ISO 15189). Further studies are needed in order to address issues related to the impact of ART on epigenetic reprogramming of the early embryo. The legal landscape regarding assisted reproduction is evolving but still remains very heterogeneous and often contradictory. The lack of legal harmonisation and uneven access to infertility treatment and PGD/PGS fosters considerable cross-border reproductive care in Europe and beyond. The aim of this paper is to complement previous publications and provide an update of selected topics that have evolved since 2005

Serum screening with Down's syndrome markers to predict pre-eclampsia and small for gestational age: Systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Reliable antenatal identification of pre-eclampsia and small for gestational age is crucial to judicious allocation of monitoring resources and use of preventative treatment with the prospect of improving maternal/perinatal outcome. The purpose of this systematic review was to determine the accuracy of five serum analytes used in Down's serum screening for prediction of pre-eclampsia and/or small for gestational age.</p> <p>Methods</p> <p>The data sources included Medline, Embase, Cochrane library, Medion (inception to February 2007), hand searching of relevant journals, reference list checking of included articles, contact with experts. Two reviewers independently selected the articles in which the accuracy of an analyte used in Downs's serum screening before the 25^thgestational week was associated with the occurrence of pre-eclampsia and/or small for gestational age without language restrictions. Two authors independently extracted data on study characteristics, quality and results.</p> <p>Results</p> <p>Five serum screening markers were evaluated. 44 studies, testing 169,637 pregnant women (4376 pre-eclampsia cases) and 86 studies, testing 382,005 women (20,339 fetal growth restriction cases) met the selection criteria. The results showed low predictive accuracy overall. For pre-eclampsia the best predictor was inhibin A>2.79MoM positive likelihood ratio 19.52 (8.33,45.79) and negative likelihood ratio 0.30 (0.13,0.68) (single study). For small for gestational age it was AFP>2.0MoM to predict birth weight < 10^thcentile with birth < 37 weeks positive likelihood ratio 27.96 (8.02,97.48) and negative likelihood ratio 0.78 (0.55,1.11) (single study). A potential clinical application using aspirin as a treatment is given as an example.</p> <p>There were methodological and reporting limitations in the included studies thus studies were heterogeneous giving pooled results with wide confidence intervals.</p> <p>Conclusion</p> <p>Down's serum screening analytes have low predictive accuracy for pre-eclampsia and small for gestational age. They may be a useful means of risk assessment or of use in prediction when combined with other tests.</p

Shock tunnel experiments on oxygen enrichment in a hydrogen fuelled scramjet

Extension of scramjet operation into the hypervelocity regime (u > 3 km/s, M > 10) is critical for their use in access-to-space systems. As flight speeds increase, the net thrust of a scramjet engine is limited by increased fuel/air mixing length requirements, as well as the decreased ratio of energy available from stoichiometric fuel/air combustion relative to the specific kinetic energy of the captured air. One possible method for addressing these issues, known as oxygen enrichment, involves the premixing of oxygen with fuel before injection. This method provides a head start for mixing and also allows the possibility of fuel combustion at greater than stoichiometric proportions. This paper describes some exploratory shock tunnel experiments involving oxygen enrichment of gaseous hydrogen fuel in a scramjet at hypervelocity conditions. These experiments were conducted in a simple rectangular duct with a central strut injector and varying levels of enrichment. The measured pressure distributions show a positive effect of enrichment and indicate how this technique could be best used to extend the performance of hypervelocity scramjets to higher flight Mach number