A cost-effective adverse-weather precision guidance system

This SAND report documents the results of an LDRD project undertaken to study the accuracy of terrain-aided navigation coupled with highly accurate topographic maps. A revolutionary new mapping technology, interferometric synthetic aperture radar (IFSAR), has the ability to make terrain maps of extremely high accuracy and spatial resolution, more than an order of magnitude better than currently available DMA map products. Using a laser altimeter and the Sandia Labs Twin Otter Radar Testbed, fix accuracies of less than 3 meters CEP were obtained over urban and natural terrain regions

High accuracy integrated global positioning system/inertial navigation system LDRD: Final report

This report contains the results of a Sandia National Laboratories Directed Research and Development (LDRD) program to investigate the integration of Global Positioning System (GPS) and inertial navigation system (INS) technologies toward the goal of optimizing the navigational accuracy of the combined GPSANS system. The approach undertaken is to integrate the data from an INS, which has long term drifts, but excellent short term accuracy, with GPS carrier phase signal information, which is accurate to the sub-centimeter level, but requires continuous tracking of the GPS signals. The goal is to maintain a sub-meter accurate navigation solution while the vehicle is in motion by using the GPS measurements to estimate the INS navigation errors and then using the refined INS data to aid the GPS carrier phase cycle slip detection and correction and bridge dropouts in the GPS data. The work was expanded to look at GPS-based attitude determination, using multiple GPS receivers and antennas on a single platform, as a possible navigation aid. Efforts included not only the development of data processing algorithms and software, but also the collection and analysis of GPS and INS flight data aboard a Twin Otter aircraft. Finally, the application of improved navigation system accuracy to synthetic aperture radar (SAR) target location is examined

Fusion of radar data to extract 3-dimensional objects LDRD final report

Interferometric Synthetic Aperture Radar (IFSAR) is a very promising technology for remote mapping of 3-Dimensional objects. In particular, 3-D maps of urban areas are extremely important to a wide variety of users, both civilian and military. However, 3-D maps produced by traditional optical stereo (stereogrammetry) techniques can be quite expensive to obtain, and accurate urban maps can only be obtained with a large amount of human-intensive interpretation work. IFSAR has evolved over the last decade as a mapping technology that promises to eliminate much of the human-intensive work in producing elevation maps. However, IFSAR systems have only been robustly demonstrated in non-urban areas, and have not traditionally been able to produce data with enough detail to be of general use in urban areas. Sandia Laboratories Twin Otter IFSAR was the first mapping radar system with the proper parameter set to provide sufficiently detailed information in a large number of urban areas. The goal of this LDRD was to fuse previously unused information derived from IFSAR data in urban areas that can be used to extract accurate digital elevation models (DEMs) over wide areas without intensive human interaction

A high-resolution, four-band SAR testbed with real-time image formation

This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories. This SAR is a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands. The SAR features real-time image formation at fine resolution in spotlight and stripmap modes. High-quality images are formed in real time using the overlapped subaperture (OSA) image-formation and phase gradient autofocus (PGA) algorithms

Influence of the ratio of planktonic to benthic diatoms on lacustrine organic matter δ13C from Erlongwan maar lake, northeast China

Carbon isotope ratio (δ13Corg) values of organic matter in lake sediments are commonly used to reconstruct environmental change, but the factors which influence change are varied and complex. Here we report δ13C values for sediments from Erlongwan maar lake in northeast China. In this record, changes in δ13C cannot be explained by simple changes in aquatic productivity. Instead, values were likely influenced by differences in the ratio between planktonic and benthic algae, as indicated by the remains of diatoms. This is because the variation of δ13Corg in algae from different habitats is controlled by the thickness of the diffusive boundary layer, which is dependent on the turbulence of the water. Compared with benthic algae, which grow in relatively still water, pelagic algae are exposed to greater water movement. This is known to dramatically reduce the thickness of the boundary layer and was found to cause even more severe δ13C depletion. In Erlongwan maar lake, low values were linked to the dominance of planktonic diatoms during the period commonly known as the Medieval Warm Period. Values gradually increased with the onset of the Little Ice Age, which we interpret as being driven by an increase in the proportion of benthic taxa, due to effect of the colder climate. The increase in planktonic diatoms at the end of the Little Ice Age, linked to higher temperature and a reduction in ice cover, resulted in a further decline in δ13Corg

Taming the tiger by the tail: modulation of DNA damage responses by telomeres

Telomeres are by definition stable and inert chromosome ends, whereas internal chromosome breaks are potent stimulators of the DNA damage response (DDR). Telomeres do not, as might be expected, exclude DDR proteins from chromosome ends but instead engage with many DDR proteins. However, the most powerful DDRs, those that might induce chromosome fusion or cell-cycle arrest, are inhibited at telomeres. In budding yeast, many DDR proteins that accumulate most rapidly at double strand breaks (DSBs), have important functions in physiological telomere maintenance, whereas DDR proteins that arrive later tend to have less important functions. Considerable diversity in telomere structure has evolved in different organisms and, perhaps reflecting this diversity, different DDR proteins seem to have distinct roles in telomere physiology in different organisms. Drawing principally on studies in simple model organisms such as budding yeast, in which many fundamental aspects of the DDR and telomere biology have been established; current views on how telomeres harness aspects of DDR pathways to maintain telomere stability and permit cell-cycle division are discussed

Untersuchungen zu Nahrungsquellen und Nahrungsbeziehungen im Pantanal von Mato Grosso

Die dieser Dissertation zugrunde liegenden Arbeiten wurde im Rahmen des Pantanal-Ecology-Projects der Universität von Cuiabá, Brasilien in Zusammenarbeit mit dem Max-Planck-Institut für Limnologie, Plön, durchgeführt. Die Dissertation basiert auf drei Manuskripten, die bei internationalen Zeitschriften zur Veröffentlichung eingereicht wurden. Mit einer Kombination aus Freilandexperimenten und einer Sammlung von Freilanddaten sollen die Nahrungsquellen von aquatischen Konsumenten des Überschwemmungsgebietes Pantanal von Mato Grosso, Brasilien beleuchtet werden. Dazu wurde die Methode der Messung der stabilen Isotopen-Verhältnisse des Kohlenstoffs (δ¹³C) und des Stickstoffs (δ¹⁵N) angewandt. Experimente zeigten, dass die δ¹³C Werte von Makrophyten während des Abbaus stabil bleiben, während die δ¹⁵N Werte großen Variationen ausgesetzt sind. Diese Veränderungen wurden auf mikrobielle Aktivitäten zurückgeführt. Es wurden Fütterungsexperimente mit den im Untersuchungsgebiet weitverbreiteten Apfelschnecken Pomacea lineata durchgeführt. Deren Ergebnisse und die Freilanddaten geben Hinweise darauf, dass die Schnecken sich scheinbar nicht von der vorherrschenden Makrophyten-Familie Pontederiaceae ernähren. Das C₄ Gras Paspalum repens ist Bestandteil ihrer Nahrung. Das partikuläre organische Material stellt ein reichlichen Nahrungsvorrat für aquatische Herbivore dar. Die Zusammensetzung des POM unterscheidet sich je nach hydrologischer Jahreszeit und StandortInhaltsverzeichnis I Danke III Zusammenfassung V Liste der Publikationen IX A EINFÜHRUNG 1 1. Das Pantanal 1 1.1. Das Pantanal-Ökologie-Projekt 1 1.2. Das Untersuchungsgebiet 4 2. Methodische Aspekte 9 2.1. Definition der Stabilen Isotope 9 2.2. Messung der Verhältnisse Stabiler Isotope 9 2.3. Die Fraktionierung der Stabilen Isotope 12 2.4. Die natürlichen Isotopen-Verhältnisse an der Basis des Nahrungskette 13 3. Die Anwendung der Messung der stabilen Isotopen-Verhältnisse bei ökologischen Fragestellungen 17 4. Kenntnisstand und Zielstellung der Publikationen 19 B ZUSAMMENFASSUNG DER PUBLIKATIONEN 23 1. Ergebnisse und Diskussion 23 2. Schlussfolgerungen und Ausblick 33 Literaturverzeichnis 35 C DIE PUBLIKATIONEN 44 Publikation I: 45 Publikation II: 65 Publikation III: 8

Feeding and growth of apple snail Pomacea lineata in the Pantanal wetland, Brazil - a stable isotope approach

Apple snails Pomacea lineata (SPIX 1827) are widespread in the tropical regions of Brazil as well as in the Pantanal wetland of Mato Grosso in the western part of the country. They have a key position in the Pantanal food web and serve as food for many animals e.g. fishes, birds, and caimans. However, little is known about their feeding preferences and growth rates. Stable isotopes have been used successfully on numerous studies as food source indicator. Therefore, the i15N and i13C values of snails from 0.45 to 3.03vcm in length, which were collected in the rainy season from March through May, were analyzed. Snails signatures revealed ambiguous evidence for food preferences. i15N and i13C values ranged between m2.8 and 12.4‰ and between m24.2 and m16.4‰, respectively. This range of values mirrors the highly variable isotope values of possible food sources comprising C3 and C4 macrophytes. To test whether all common food sources were similarly assimilated, feeding experiments with different diets were conducted. Snail eggs were reared in tanks and offered different but single plants. Snails fed different diets and i13C values of the food were reflected in the animal tissue. Growth varied considerably in experiments with different diets indicating the preference for certain food sources. Also, the fractionation of nitrogen isotopes between food and animal varied from 0.1 to 17.0‰. The results are explained by different feeding habits, and it is supposed that animals fed either on the plant itself or on bacteria mats growing in the tanks. In an additional experiment juvenile snails were offered one single food with a distinctive C4 grass signature. These snails did not grow detectably, but nevertheless isotope signatures approached to values of the diet

Untersuchungen zu Nahrungsquellen und Nahrungsbeziehungen im Pantanal von Mato Grosso

Die dieser Dissertation zugrunde liegenden Arbeiten wurde im Rahmen des Pantanal-Ecology-Projects der Universität von Cuiabá, Brasilien in Zusammenarbeit mit dem Max-Planck-Institut für Limnologie, Plön, durchgeführt. Die Dissertation basiert auf drei Manuskripten, die bei internationalen Zeitschriften zur Veröffentlichung eingereicht wurden. Mit einer Kombination aus Freilandexperimenten und einer Sammlung von Freilanddaten sollen die Nahrungsquellen von aquatischen Konsumenten des Überschwemmungsgebietes Pantanal von Mato Grosso, Brasilien beleuchtet werden. Dazu wurde die Methode der Messung der stabilen Isotopen-Verhältnisse des Kohlenstoffs (δ¹³C) und des Stickstoffs (δ¹⁵N) angewandt. Experimente zeigten, dass die δ¹³C Werte von Makrophyten während des Abbaus stabil bleiben, während die δ¹⁵N Werte großen Variationen ausgesetzt sind. Diese Veränderungen wurden auf mikrobielle Aktivitäten zurückgeführt. Es wurden Fütterungsexperimente mit den im Untersuchungsgebiet weitverbreiteten Apfelschnecken Pomacea lineata durchgeführt. Deren Ergebnisse und die Freilanddaten geben Hinweise darauf, dass die Schnecken sich scheinbar nicht von der vorherrschenden Makrophyten-Familie Pontederiaceae ernähren. Das C₄ Gras Paspalum repens ist Bestandteil ihrer Nahrung. Das partikuläre organische Material stellt ein reichlichen Nahrungsvorrat für aquatische Herbivore dar. Die Zusammensetzung des POM unterscheidet sich je nach hydrologischer Jahreszeit und StandortInhaltsverzeichnis I Danke III Zusammenfassung V Liste der Publikationen IX A EINFÜHRUNG 1 1. Das Pantanal 1 1.1. Das Pantanal-Ökologie-Projekt 1 1.2. Das Untersuchungsgebiet 4 2. Methodische Aspekte 9 2.1. Definition der Stabilen Isotope 9 2.2. Messung der Verhältnisse Stabiler Isotope 9 2.3. Die Fraktionierung der Stabilen Isotope 12 2.4. Die natürlichen Isotopen-Verhältnisse an der Basis des Nahrungskette 13 3. Die Anwendung der Messung der stabilen Isotopen-Verhältnisse bei ökologischen Fragestellungen 17 4. Kenntnisstand und Zielstellung der Publikationen 19 B ZUSAMMENFASSUNG DER PUBLIKATIONEN 23 1. Ergebnisse und Diskussion 23 2. Schlussfolgerungen und Ausblick 33 Literaturverzeichnis 35 C DIE PUBLIKATIONEN 44 Publikation I: 45 Publikation II: 65 Publikation III: 8