Physical lumping methods for developing linear reduced models for high speed propulsion systems

In gasdynamic systems, information travels in one direction for supersonic flow and in both directions for subsonic flow. A shock occurs at the transition from supersonic to subsonic flow. Thus, to simulate these systems, any simulation method implemented for the quasi-one-dimensional Euler equations must have the ability to capture the shock. In this paper, a technique combining both backward and central differencing is presented. The equations are subsequently linearized about an operating point and formulated into a linear state space model. After proper implementation of the boundary conditions, the model order is reduced from 123 to less than 10 using the Schur method of balancing. Simulations comparing frequency and step response of the reduced order model and the original system models are presented

Measurement of the Cosmic Optical Background using the Long Range Reconnaissance Imager on New Horizons

The cosmic optical background is an important observable that constrains energy production in stars and more exotic physical processes in the universe, and provides a crucial cosmological benchmark against which to judge theories of structure formation. Measurement of the absolute brightness of this background is complicated by local foregrounds like the Earth's atmosphere and sunlight reflected from local interplanetary dust, and large discrepancies in the inferred brightness of the optical background have resulted. Observations from probes far from the Earth are not affected by these bright foregrounds. Here we analyze data from the Long Range Reconnaissance Imager (LORRI) instrument on NASA's New Horizons mission acquired during cruise phase outside the orbit of Jupiter, and find a statistical upper limit on the optical background's brightness similar to the integrated light from galaxies. We conclude that a carefully performed survey with LORRI could yield uncertainties comparable to those from galaxy counting measurements.Comment: 35 pages, 11 figures, published in Nature Communication

Comparative ergonomic workflow and user experience analysis of MRI versus fluoroscopy-guided vascular interventions:an iliac angioplasty exemplar case study

Purpose A methodological framework is introduced to assess and compare a conventional fluoroscopy protocol for peripheral angioplasty with a new magnetic resonant imaging (MRI)-guided protocol. Different scenarios were considered during interventions on a perfused arterial phantom with regard to time-based and cognitive task analysis, user experience and ergonomics. Methods Three clinicians with different expertise performed a total of 43 simulated common iliac angioplasties (9 fluoroscopic, 34 MRI-guided) in two blocks of sessions. Six different configurations for MRI guidance were tested in the first block. Four of them were evaluated in the second block and compared to the fluoroscopy protocol. Relevant stages’ durations were collected, and interventions were audio-visually recorded from different perspectives. A cued retrospective protocol analysis (CRPA) was undertaken, including personal interviews. In addition, ergonomic constraints in the MRI suite were evaluated. Results Significant differences were found when comparing the performance between MRI configurations versus fluoroscopy. Two configurations [with times of 8.56 (0.64) and 9.48 (1.13) min] led to reduce procedure time for MRI guidance, comparable to fluoroscopy [8.49 (0.75) min]. The CRPA pointed out the main influential factors for clinical procedure performance. The ergonomic analysis quantified musculoskeletal risks for interventional radiologists when utilising MRI. Several alternatives were suggested to prevent potential low-back injuries. Conclusions This work presents a step towards the implementation of efficient operational protocols for MRI-guided procedures based on an integral and multidisciplinary framework, applicable to the assessment of current vascular protocols. The use of first-user perspective raises the possibility of establishing new forms of clinical training and education

Biomineralisations en carbonate de calcium chez les métazoaires : tendances macro-évolutives - Défis pour la décennie à venir.

16 pagesInternational audienceCalcium carbonate-based biominerals, also referred as biocalcifications, are the most abundant biogenic mineralized products at the surface of the Earth. In this paper, we summarize general concepts on biocalcifications and we sketch macro-evolutionary trends throughout the history of the Earth, from Archean to Phanerozoic times. Then, we expose five fundamental issues that represent key-challenges in biocalcification researches for the coming decade: the first one concerns the comprehension of the micro- and nano-structure of calcium carbonate biominerals from a mineral viewpoint, while the second one deals with the understanding of the dynamic process of their fabrication. The third one treats the subtle interplay between organics and the mineral phase. The fourth issue focuses on an environmental challenge related to ocean acidification (OA); at last, the diagenetic processes that affect biogenic calcium carbonate mineral constitute the fifth issue.Les biocalcifications, ou biominéraux en carbonate de calcium, sont les minéralisations biogéniques les plusabondantes à la surface du globe. Le présent article montre comment les biocalcifications sont à l’origine de certainsconcepts scientifiques d’importance, et comment elles ont évolué au cours des temps géologiques, de l’Archéen au Phanérozoïque.Cinq défis majeurs y ayant trait sont ensuite identifiés pour les années à venir : le premier vise à comprendrela structure des biocalcifications aux échelles micro- et nanométriques, tandis que le second s’interroge sur leprocessus dynamique de leur formation. Le troisième défi traite des interactions complexes entre constituants organiqueset phase minérale. Le quatrième se focalise sur des questions environnementales cruciales, notamment l’acidificationocéanique. Le dernier défi consiste à comprendre comment les phénomènes diagénétiques et la fossilisationaffectent les biocalcifications dans leur globalité

North-south asymmetry of the high-latitude thermospheric density:IMF BY effect

Previous studies have established that the y component of the interplanetary magnetic field (IMF By) plays a role in the north-south asymmetry of the high-latitude plasma convection and wind. The effect of the positive/negative IMF By in the Northern Hemisphere resembles the effect that the negative/positive IMF By would have in the Southern Hemisphere. In this study, we demonstrate that the IMF By effect can also contribute to the hemispheric asymmetry of the thermospheric density. We use high-accuracy air drag measurements from the CHAllenging Minisatellite Payload (CHAMP) satellite and SuperMAG AE index during the period 2001–2006 to examine the response of the high-latitude thermospheric density to geomagnetic activity. Our statistical analysis reveals that the density response at 400 km is greater in the Southern Hemisphere under positive IMF By conditions, and greater in the Northern Hemisphere under negative IMF By conditions. The results suggest that the IMF By effect needs to be taken into account in upper atmospheric modeling for an accurate description of high-latitude densities during periods of enhanced geomagnetic activity

Family Naming Practices and Intergenerational Kinship Affiliations

The study of naming practices has captured the interest of researchers in a variety of related disciplines. Studies of names and naming have led to a body of literature suggesting that naming practices are infused with meaning and reflect emotional ties between family members. This study examined four research hypotheses related to family naming practices in an intergenerational sample of Mormon women. Ninety women from three generations of 30 families participated in the study. Through telephone interviews, each woman completed a survey designed to gather information about sources of children\u27s names, kinship affiliations, and religiosity. The information gathered from the surveys was analyzed using three statistical analyses: descriptive statistics, the chi square test of significance, and multiple regression. Data analyses indicated that there were no significant differences in naming practices in this group and that naming practices were similar across generations. Analyses of the relationship between family closeness and naming indicated that there was no significant relationship between closeness to the family of origin and naming for family members. However, closeness to the family of procreation was found to be inversely related to naming for relatives. Both of the religiosity items --level of church activity and frequency of church attendance for both husbands and wives--were found to be inversely related to naming children for relatives. Further data analyses revealed that child gender was the factor that contributed most heavily to whether or not children were named for relatives

Applications of DNA capture in ancient DNA research

Ancient DNA has become an indispensable resource of fundamental research. Especially the combination of DNA capture methods and Next Generation Sequencing (NGS) has allowed to exploit the full potential of ancient DNA. In this dissertation I present three studies which involve capture of ancient DNA to answer different scientific questions. In my first study I bioinformatically reconstruct the mitochondrial genome of the extinct giant deer Megaloceros giganteus after applying mitochondrial DNA capture and sequencing. Using the giant deer's reconstructed mitochondrial genome I then apply phylogenetic analyses that allow to resolve the giant deer's placement within the cervid family tree and reaffirm the fallow deer being its closest extant relative. Mitochondrial DNA capture also provides the basis for the next study, in which I investigate the effects of X-rays on ancient DNA. Different radiation settings are explored including those commonly used in computed tomography (CT) of anthropological and palaeontological specimens. The results allow to define 200 Gray (Gy) as the maximum absorbed X-ray dose which can still be regarded harmless to ancient DNA molecules. No X-radiation induced effects can be observed below this threshold. In my third study I develop and apply capture of 488 human immunity genes in order to compare the immunogenetic makeup of Late Medieval plague (Yersinia pestis) victims and their modern day successors from Ellwangen, Southern Germany. Applying bioinformatic tools allows me to investigate kinship within both populations, determine genetic continuity between past and present, and reconstruct the Human Leukocyte Antigen (HLA) allelic profiles of both populations. While the majority of HLA alleles do not differ in their frequencies, HLA-B51:01 and HLA-DRB113 show significant frequency differences between both populations, potentially indicative of selective pressure through Yersinia pestis