Space Based Real-Time Kinematic GPS for National Geodetic Survey Texas Height Modernization

Height Modernization is a program in NOAA\u27s National Geodetic Survey (NGS) that uses the Global Positioning System (GPS) and other new technologies to increase the accuracy of elevation measurements that comprise the vertical portion of the National Spatial Reference System (NSRS). Height Modernization Program within NGS is working with states to improve the height component of their survey control networks and related products. Texas A&M University- Corpus Christi (A&M-CC) was designated as the recipient of a grant under the Program during the most recent Congressional cycle. In order to best coordinate and manage the activities funded by the grant, A&M-CC has established the Texas Spatial Reference Center (TxSRC). TxSRC will assist state agencies, private companies, public utilities and federal agencies in their efforts to improve the statewide network of control points as well as to support their use of GPS Continuing Operating Reference Stations (CORS). TxSRC plans to support the development of a statewide system of broadcasting Networked Transport of RTCM via Internet Protocol (NTRIP) for RTK-GPS. TxSRC will research methods of using NTRIP to locate and to collect information on geodetic monuments. NTRIP use is being considered as a way to overcome the limitations of RTK. Current RTKGPS implementations require cellular or radio modem connections as the mechanism for receiving differential corrections. This infrastructure is not available in many remote and rural areas of Texas. It is proposed that a space-based (SB) RTK-GPS should be used to provide corrections in areas where no other corrections can be obtained without additional terrestrial infrastructure development. The proposed solution uses the Hughes Network System\u27s Directway broadband internet satellite to send corrections to remote sites. Data would be received at the remote site and then locally broadcast to rover users. This SB-RTK-GPS will allow TxSRC to utilize the existing network of CORS sites. The CORS will be used to generate the corrections that provide NTRIP. This research will investigate the configuration concerns and other and technical aspects of this proposed methodology. Reprinted with permission from The Institute of Navigation (http://ion.org/) and The Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation, (pp. 1079-1082). Fairfax, VA: The Institute of Navigation

Quadruplex digital flight control system assessment

Described are the development and validation of a double fail-operational digital flight control system architecture for critical pitch axis functions. Architectural tradeoffs are assessed, system simulator modifications are described, and demonstration testing results are critiqued. Assessment tools and their application are also illustrated. Ultimately, the vital role of system simulation, tailored to digital mechanization attributes, is shown to be essential to validating the airworthiness of full-time critical functions such as augmented fly-by-wire systems for relaxed static stability airplanes

Analytical sensor redundancy assessment

The rationale and mechanization of sensor fault tolerance based on analytical redundancy principles are described. The concept involves the substitution of software procedures, such as an observer algorithm, to supplant additional hardware components. The observer synthesizes values of sensor states in lieu of their direct measurement. Such information can then be used, for example, to determine which of two disagreeing sensors is more correct, thus enhancing sensor fault survivability. Here a stability augmentation system is used as an example application, with required modifications being made to a quadruplex digital flight control system. The impact on software structure and the resultant revalidation effort are illustrated as well. Also, the use of an observer algorithm for wind gust filtering of the angle-of-attack sensor signal is presented

The Origins of Lactase Persistence in Europe

Lactase persistence (LP) is common among people of European ancestry, but with the exception of some African, Middle Eastern and southern Asian groups, is rare or absent elsewhere in the world. Lactase gene haplotype conservation around a polymorphism strongly associated with LP in Europeans (−13,910 C/T) indicates that the derived allele is recent in origin and has been subject to strong positive selection. Furthermore, ancient DNA work has shown that the −13,910*T (derived) allele was very rare or absent in early Neolithic central Europeans. It is unlikely that LP would provide a selective advantage without a supply of fresh milk, and this has lead to a gene-culture coevolutionary model where lactase persistence is only favoured in cultures practicing dairying, and dairying is more favoured in lactase persistent populations. We have developed a flexible demic computer simulation model to explore the spread of lactase persistence, dairying, other subsistence practices and unlinked genetic markers in Europe and western Asia's geographic space. Using data on −13,910*T allele frequency and farming arrival dates across Europe, and approximate Bayesian computation to estimate parameters of interest, we infer that the −13,910*T allele first underwent selection among dairying farmers around 7,500 years ago in a region between the central Balkans and central Europe, possibly in association with the dissemination of the Neolithic Linearbandkeramik culture over Central Europe. Furthermore, our results suggest that natural selection favouring a lactase persistence allele was not higher in northern latitudes through an increased requirement for dietary vitamin D. Our results provide a coherent and spatially explicit picture of the coevolution of lactase persistence and dairying in Europe

A novel polymorphism associated with lactose tolerance in Africa: multiple causes for lactase persistence?

Persistence or non-persistence of lactase expression into adult life is a polymorphic trait that has been attributed to a single nucleotide polymorphism (C-13910T) in an enhancer element 13.9 kb upstream of the lactase gene (LCT). The -13910*T allele occurs at very high frequency in northern Europeans as part of a very long haplotype (known as A), and promotes binding of the transcription factor Oct-1. However, -13910*T is at very low frequency in many African milk drinking pastoralist groups where lactase persistence phenotype has been reported at high frequency. We report here for the first time, a cohort study of lactose digester and non-digester Sudanese volunteers and show there is no association of -13910*T or the A haplotype with lactase persistence. We support this finding with new genotype/phenotype frequency comparisons in pastoralist groups of eastern African and Middle Eastern origin. Resequencing revealed three new SNPs in close proximity to -13910*T, two of which are within the Oct-1 binding site. The most frequent of these (-13915*G) is associated with lactose tolerance in the cohort study, providing evidence for a cis -acting effect. Despite its location, -13915*G abolishes, rather than enhances Oct-1 binding, indicating that this particular interaction is unlikely to be involved in lactase persistence. This study reveals the complexity of this phenotypic polymorphism and highlights the limitations of C-13910T as a diagnostic test for lactase persistence status, at least for people with non-European ancestry. © Springer-Verlag 2006

Geriatric Emergency Medicine Fellowships: Current State of Specialized Training for Emergency Physicians in Optimizing Care for Older Adults

Improving emergency department (ED) care for older adults is a critical issue in emergency medicine. Institutions throughout the United States and Canada have recognized the growing need for a workforce of emergency physician (EP) leaders focused on clinical innovation, education, and research and have developed specialized fellowship training in geriatric emergency medicine (GEM). We describe here the overview, structure, and curricula of these fellowships as well as successes and challenges they have encountered. Seven GEM fellowships are active in the United States and Canada, with five offering postresidency training only, one offering fellowship training during residency only, and one offering both. The backbone of the curriculum for all fellowships is the achievement of core competencies in various aspects of GEM, and each includes clinical rotations, teaching, and a research project. Evaluation strategies and feedback have allowed for significant curricular changes as well as customization of the fellowship experience for individual fellows. Key successes include an improved collaborative relationship with geriatrics faculty that has led to additional initiatives and projects and former fellows already becoming regional and national leaders in GEM. The most critical challenges have been ensuring adequate funding and recruiting new fellows each year who are interested in this clinical area. We believe that interest in GEM fellowships will grow and that opportunities exist to combine GEM fellowship training with a focus in research, administration, or health policy to create unique new types of highly impactful specialized training. Future research may include exploring former fellows' postfellowship experiences, careers, accomplishments, and contributions to GEM to better understand the impact of GEM fellowships