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Terrestrial thermal environments can serve as analogs for subsurface environments in the search for life because they regularly host microbial communities, which may leave behind biosignatures. This study focused on an acid-sulfate hydrothermal site as an analog for a potentially habitable environment on Mars. A weathered boulder in the thermal area was dissected, revealing an interior marked with disconnected horizons of differently colored materials, very low pH, and increasing temperature. The mineralogy comprised weathering products from andesite (kaolinite, quartz, clinoptilolite) along with sulfate salts (alunite, jarosite, tschermigite, and copiapite) formed by oxidation of sulfide and ferrous iron. Characterization of organic matter in this boulder and several soil samples yielded interesting but surprising results. Both mass spectrometry and Raman spectroscopy identified organic compounds in portions of the soils and the boulder. Jarosite-associated samples showed more numerous and diverse organic signatures than did Al-bearing silicate samples, despite the lower total organic carbon content of the jarosite-associated soils (0.69 ± 0.07 wt% Corg) compared to the Al-bearing samples (1.28 ± 0.13 wt% Corg). Results from our geochemical, mineralogical, and spectroscopic study of hydrothermal alteration products and salts inform the heterogeneous distribution of inorganic and organic materials that could delineate habitats and demonstrate the limits on organic matter detectability using different analytical techniques. Furthermore, we relate our measurements and results directly to current and upcoming martian missions, and we provide recommendations for detection and characterization of minerals and organics as biosignatures on Mars using instruments on future missions.

Doppler velocity estimation in pulse-Doppler radar is done by evaluating the target returns of bursts of pulses. While this provides convenience and accuracy, it requires multiple pulses. In adaptive and cognitive radar systems, the ability to adapt on consecutive pulses, instead of bursts, brings potential performance benefits. Hence, with radar transceiver arrays growing increasingly larger in their number of elements over the years, it may be time to re-evaluate how Doppler velocity can be estimated when using large planar arrays. In this work, we present variance bounds on the estimation of velocity using the Doppler shift as it appears in the array model. We also propose an efficient method of performing the velocity estimation and we verify its performance using Monte Carlo simulations.

Glacial environments can have significant impacts on the surrounding landscape and nearby populations when affected by volcanic activity. As such, glaciovolcanic interactions and related hazards have received substantial attention during the last few decades. In contrast, the study of void spaces created by these interactions-glaciovolcanic cave systems-remains underrepresented. This review outlines the global distribution of glaciovolcanic caves and describes examples of both historical and ongoing research advances, most of which are limited to volcanoes of the Cascade Volcanic Arc and Antarctica. Examples range from a largely static fumarolic ice cave system in the crater of Mount Rainier to glaciovolcanic cave genesis and evolution in the crater of Mount St. Helens, where the advancing glacier ice is interacting with ongoing fumarolic activity and generating new cave systems. This review includes various volcanic subfields and also brings together additional disciplines including speleology, microbiology, and astrobiology. Due to the importance of glaciovolcanic caves in the hydrothermal cycle of volcanic systems, the global fight against antibiotic resistance, and their implications for understanding volcano-ice interactions beyond Earth, research on these systems is expanding. Kamchatka, Alaska, and Iceland have notable potential for further studies, while known research sites still hold open questions, including better understanding of the environmental parameters affecting cave genesis and persistence, the effect of glaciovolcanic cave development on underlying hydrothermal systems, and cataloging the biodiversity of glaciovolcanic cave environments. Glazial beeinflusste Gebiete können in Verbindung mit vulkanischer Aktivität große Auswirkungen auf die umliegende Landschaft und nahegelegene Ansiedlungen haben. Aufgrund dessen haben Vulkan-Eis-Interaktionen und damit verbundene Gefahren innerhalb der letzten Jahrzehnte große Beachtung gefunden. Im Gegensatz dazu sind Studien zu Hohlräumen im Eis (sogenannten vulkanischen Gletscherhöhlen), die durch diese Interaktionen entstehen, unterrepräsentiert. Dieser Artikel zeigt das weltweite Vorkommen vulkanischer Gletscherhöhlen auf und beschreibt Beispiele vergangener und aktueller Forschung, wobei diese vor allem auf Vulkane des Kaskadengebirges und der Antarktis beschränkt ist. Beispiele reichen dabei von einem relativ statischen System vulkanischer Gletscherhöhlen in Firneis, wie sie am Mount Rainier vorkommen, bis hin zur Entstehung und Entwicklung neuer Höhlensysteme im Krater des Mount St. Helens, wo das fortschreitende Gletschereis mit anhaltender fumarolischer Tätigkeit interagiert und dadurch neue Höhlen entstehen lässt. Dieser Artikel umfasst diverse vulkanische Arbeitsbereiche, aber schließt ebenfalls andere Disziplinen wie die Speleologie, Mikro- und Astrobiologie ein. Aufgrund der Bedeutung vulkanischer Gletscherhöhlen für den hydrothermalen Kreislauf von vulkanischen Systemen, den globalen Kampf gegen Antibiotika-Resistenz sowie ihrer Bedeutung, Vulkan-Eis-Interaktionen abseits des Planeten Erde zu verstehen, erfährt die Erforschung dieser Systeme steten Zuwachs. Kamtschatka, Alaska und Island haben hohes Potenzial für weitere Forschung, während bisher bekannte Gebiete nach wie vor Fragen offen lassen. Diese beinhalten ein besseres Verständnis von natürlichen Faktoren, die Entstehung und Fortbestehen der Höhlen beeinflussen, Auswirkungen vulkanischer Gletscherhöhlensysteme auf das darunterliegende Hydrothermalsystem sowie eine Katalogisierung der Biodiversität dieser Umgebungen.

It is well known that noise-like waveforms have the inherent property of suppressing ambiguities due to their nonrepetitive nature, as opposed to the more classical linear frequency modulated (LFM) pulsed waveforms. This aperiodicity also improves the robustness against jammers, making these waveforms harder to detect and classify by an enemy. However, noise waveforms are Doppler sensitive, requiring the use of Doppler-dependent matched filters for proper range compression. Also, when processed with classical matched filters, noise waveforms have sidelobes that spread out across the whole range-Doppler plane, potentially masking weak targets in the presence of strong ones. A possible solution to reduce the sidelobe interference is to use sparse signal processing (SSP). In this article, we demonstrate with simulated and experimental data how noise waveforms can be used in combination with SSP for unambiguous detection of strong as well as weak targets, improving upon the performance of more conventional LFM pulsed waveforms. © 1986-2012 IEEE.

In the past decades, there has been an extensive research interest in the areas of both waveform diversity/design and advanced signal processing algorithms departing from the more classical solutions based on Linear Frequency Modulated (LFM) pulses and Matched Filters (MF). In the waveform diversity community, especially within the context of spectrum sharing, MIMO and cognitive radars, several waveform optimization and design methodologies have been studied, see [1], [2] and references therein. In parallel to waveform design, several signal processing techniques have also been proposed which exploit some kind of prior knowledge and/or iterative algorithms to improve the performance of the more classical MF, such as the Adaptive Pulse Compression(APC) [3], MUSIC [4], CLEAN [5] and Sparse Signal Processing (SSP) [6], [7]. In this paper we present some results and examples to show how the combination of waveform design with SSP can lead to improved performance in radar compared to the more classical approach.

Research experience provides critical training for new biomedical research scientists. Students from underrepresented populations studying science, technology, engineering, and mathematics (STEM) are increasingly recruited into research pathways to diversify STEM fields. However, support structures outside of research settings designed to help these students navigate biomedical research pathways are not always available; nor are program support components outside the context of laboratory technical skills training and formal mentorship well understood. This study leveraged a multi-institutional research training program, Enhancing Cross-Disciplinary Infrastructure and Training at Oregon (EXITO), to explore how nine institutions designed a new curricular structure (Enrichment) to meet a common goal of enhancing undergraduate research training and student success. EXITO undergraduates participated in a comprehensive, 3-year research training program with the Enrichment component offered across nine sites: three universities and six community colleges, highly diverse in size, demographics, and location. Sites’ approaches to supporting students in the training program were studied over a 30-month period. All sites independently created their own nonformal curricular structures, implemented interprofessionally via facilitated peer groups. Site data describing design and implementation were thematically coded to identify essential programmatic components across sites, with student feedback used to triangulate findings. Enrichment offered students time to critically reflect on their interests, experiences, and identities in research; network with peers and professionals; and support negotiation of hidden and implicit curricula. Students reported the low-pressure setting and student-centered curriculum balanced the high demands associated with academics and research. Core curricular themes described Enrichment as fostering a sense of community among students, exposing students to career paths and skills, and supporting development of students’ professional identities. The non-formal, interprofessional curricula enabled students to model diverse biomedical identities and pathways for each other while informing institutional structures to improve diverse undergraduate students’ success in academia and research.

Automotive engineers are repeatedly faced with the issue of choosing radars with the best angular resolution while having reduced processing times. In this paper, a novel extrapolation method is presented to estimate the amplitudes and phases for virtual antenna elements at the receiver periphery. This method has shown to resolve two targets where the (real) baseline receiver antenna cannot. Furthermore, a comparison study is provided which considers different extrapolation methods that can be applied to the system. Together with other techniques for improving resolution, such as Multiple-Input Multiple-Output (MIMO) radars, beamsteering for increased power distribution, and compressed sensing for optimising sampling requirements, a radar system based on the fusion of these techniques can provide a powerful new platform which can fast process and accurately detect targets.

Infrastructure maintenance programs establish schedules for routine inspections of highway bridges with little consideration of their current conditions. The time interval between two inspections is traditionally set based on experience and on engineering judgment. For example, in the US considerable expenditures are incurred to meet the required biennial routine inspection of all bridges many of which may be in good condition. It is therefore of great interest for the engineering community to develop an approach to control inspection schedules of individual bridges and minimize their associated costs using rational criteria that account for the lower risk of postponing the inspection of bridges that are subject to reduced deterioration mechanisms and low traffic loadings. The implementation of such a risk-based approach would go a long way in helping optimize the limited resources available for maintaining the vast highway infrastructure system. The object of this Ph.D. dissertation is to develop a rational approach for determining a risk-based optimum time interval between bridge inspections. The proposed theoretical approach subsequently serves for proposing a simple procedure that is implementable in routine practice by bridge engineers using easily available bridge-specific data. To illustrate the proposed procedure using actual bridge data, the work uses highway data from the state of New York (NYS) in the United States of America (USA) in the form of Weigh-in-Motion (WIM) truck traffic data and bridge records provided through the National Bridge Inventory (NBI) database. These data are used to develop a theoretical framework able to define the capacity of bridges probabilistically and the risk of bridge failure if a bridge’s inspection is deferred for a limited period of time. The calculations performed in this dissertation based on data collected in the state of New York are limited to simple span composite steel-concrete superstructures that constitute a large proportion of short to medium span bridges in North America. However, the same concepts can be extended to other types of superstructures and other regions of the world as appropriate data become available. The conclusions of this study include the demonstration of the inadequacy of utilizing a standard two-year inspection interval for all bridges. To overcome this problem a simplified procedure is proposed for an easy practical engineers’ application. Els programes de manteniment d'infraestructures estableixen plans periòdics d'inspecció bàsica en els quals l'estat actual dels ponts té relativament poca importància a l'hora de definir l'interval de temps. L'interval temporal entre dues inspeccions es basa normalment en la practica habitual i en la experiència passada. Per exemple, als Estats Units d'Amèrica una gran part del pressupost de despesa destinat al manteniment de la xarxa d'infraestructures es deriva al pla d'inspeccions biennal de ponts tot i que, aquests, en molts casos mostren bones condicions estructurals. Per això la comunitat enginyeril està interessada en el desenvolupament de protocols que controlin el pla d'inspecció de ponts i que minimitzin els costos associats a traves de criteris racionals. Aquets criteris han de ser capaços de reconèixer els ponts que presenten un risc alt degut a la elevada exposició a processos de deteriorament i a sobrecarrega de tràfic intens i minimitzar els costos d'inspecció associats. La implementació d'estratègies basades en el càlcul del risc permet optimitzar el pressupost total disponible per al manteniment de les xarxes de carreteres. L'objecte d'aquesta tesi doctoral es el desenvolupament d'un procediment racional basat en el càlcul del risc per a estimar l'interval òptim entre dues inspeccions bàsiques. L'estratègia teòrica proposada es fa servir posteriorment per a la aplicació pràctica d'aquests criteris utilitzant dades inicials fàcils d'obtenir per l'usuari final que estigui interessat en aplicar el mètode per a un pont en concret. La metodologia proposada en aquest treball utilitza dades de la xarxa de carreteres de l'estat de Nova York (NYS) als Estats Units d'Amèrica (USA), a partir de mesures de tràfic del tipus Weigh-in-Motion (WIM) i de informacions provinents de la base de dades del National Bridge Inventory (NBI). Aquestes dades es fan servir per a desenvolupar una eina metodològica capaç de calcular la capacitat estructural de superestructures des del punt de vista probabilista i quantificar l'increment de risc al que la societat està sotmesa en cas de decidir incrementar l'interval d'inspecció per damunt dels 2 anys. Per al càlcul dels intervals d'inspecció es fa servir el concepte de risc, que a la vegada es basa en models de càlcul probabilistes. L'interval d'inspecció òptim s'obté minimitzant el risc de fallada obtingut combinant la probabilitat de fallada amb el cost associat. El cost de fallada s'obté estimant els costos potencials relatius com víctimes, ferits, reconstrucció del pont, interrupció del tràfic vehicular, impacte ambiental i cost d'inspecció. Els càlculs duts a terme en aquesta tesi estan basats en dades de la regió del estat de Nova York i limitats a ponts simplement recolzats amb superestructura mixta acer-formigó que constitueix una important tipologia en l'àmbit nord americà. No obstant, els mateixos conceptes poden ser aplicats a altres regions del mon a mesura que la informació necessària estigui a disposició. L'estudi demostra la ineficiència d'utilitzar un interval d'inspecció de dos anys per a tots els ponts i proposa una metodologia simplificada per calcular l'interval d'inspecció recomanat per ser implementat en la pràctica engineril d'una manera senzilla. Los programas de mantenimiento de infraestructuras establecen planes periódicos de inspección básica en los cuales el posible estado de los puentes en el momento de la inspección tiene relativamente poca importancia. El intervalo temporal entre dos inspecciones se fija sobre la base de la práctica habitual y sobre experiencia pasada. Por ejemplo, en los Estados Unidos de América una gran parte del presupuesto de gasto destinado al mantenimiento de la red de infraestructuras se deriva al plan de inspecciones bienales de puentes aunque en muchos casos muestran buenas condiciones estructurales. Por esta razón, es de suma importancia para la comunidad el desarrollo de protocolos para controlar el plan de inspección de puentes y minimizar los costes asociados a través de criterios racionales, para poder destinar los recursos asignados a inspección allí donde más falta hacen. Dichos criterios tienen que ser capaces de reconocer aquellos puentes que presentan mayor riesgo debido a la exposición a procesos de deterioro y a sobrecarga de tráfico intenso y minimizar los costes de inspección asociados. La implementación de estrategias basadas en criterios de riesgo permite optimizar el presupuesto total disponible para el mantenimiento de las redes de carreteras El objeto de esta tesis doctoral es el desarrollo de un procedimiento racional basado en el cálculo del riesgo para determinar el intervalo óptimo entre dos inspecciones básicas. El enfoque teórico propuesto se emplea posteriormente para la aplicación en la práctica de dichos criterios utilizando datos de partida fáciles de obtener para el usuario final que esté interesado en aplicar el método para un puente en concreto. La metodología propuesta en este trabajo se materializa a través de los datos disponibles de la red de carreteras del estado de Nueva York (NYS) en Estados Unidos de América (USA), desde mediciones de tráfico del tipo Weigh-in-Motion (WIM) hasta informaciones en el marco de la base de datos del National Bridge Inventory (NBI). Esos datos se utilizan para desarrollar una base metodológica capaz de calcular la capacidad portante de superestructuras desde el punto de vista probabilista y cuantificar el incremento de riesgo que supone incrementar el intervalo de la inspección básica, actualmente fijado en dos años En la práctica actual, el cálculo de la capacidad portante de puentes sujetos a sobrecarga de tráfico (en estado límite de servicio y último) se lleva a cabo a partir de modelos típicamente elástico-lineales en los que se evalúan los esfuerzos para el elemento más crítico y sucesivamente se considera el cálculo no lineal para la verificación de dicho elemento. Este enfoque está aceptado y ha demostrado su validez y fiabilidad en numerosas aplicaciones. Sin embargo, a pesar de que estos modelos pueden tener en cuenta el deterioro detectado en las campañas de inspección, normalmente no consideran sobrecargas de tráfico realistas, el comportamiento estructural del conjunto del puentes y no sólo de sus elementos por separado, o la evolución posible del deterioro entre intervalos de inspección. En este estudio, se emplean datos de tráfico real obtenidos de sistemas WIM para estimar la sobrecarga de tráfico máxima esperada que puede ser bastante diferente de la que típicamente sugieren los códigos de diseño y evaluación estructural de puentes. De la misma manera, la respuesta conjunta de la estructura se tiene en cuenta en este trabajo utilizando modelos capaces de simular el comportamiento no-lineal de los materiales y la evolución de la redistribución de los esfuerzos cuando la estructura se encuentra en rangos de deformaciones próximos a rotura. Esto permite mejorar el cálculo de la capacidad estructural y detectar aquellos puentes cuya configuración tipológica y topológica resulta en un comportamiento redundante que no es posible tener en cuenta en los modelos de cálculo tradicionales. Además, se incluye en el modelo el deterioro de los materiales tras estudiar datos históricos sobre la pérdida de capacidad portante de una gran cantidad de puentes seleccionados del NBI. Para el cálculo de los intervalos de inspección se emplea el concepto de riesgo, que a su vez se basa en modelos de cálculo probabilistas. El intervalo de inspección óptimo se obtiene minimizando el riesgo de fallo obtenido combinando la probabilidad de fallo con el coste asociado. El coste del fallo se obtiene estimando los costes potenciales relativos como víctimas, heridos, reconstrucción del puente, interrupción del tráfico vehicular, impacto ambiental y coste de inspección. Los cálculos llevados a cabo en esta tesis están basados en datos de la región del estado de Nueva York y limitados a puentes simplemente apoyados con superestructura mixta acero-hormigón que constituye una importante tipología en el ámbito norteamericano. Sin embargo los mismos conceptos pueden ser aplicados a otras regiones del mundo a medida que la información necesaria se encuentre disponible. El estudio demuestra la ineficiencia de utilizar un intervalo de inspección de dos años para todos los puentes y propone una metodología simplificada para calcular el intervalo de inspección recomendado para ser implementada en la práctica ingenieril de una forma sencilla. Enginyeria de la construcció

In this article a novel waveform based on agile (or irregular) pulse intervals is presented as a potential approach to simultaneously resolve both range and Doppler ambiguities using a single burst in radar measurements containing very far away and/or very fast targets. The paper shows that, the combination of irregularly spaced transmitted pulses with Sparse Signal Processing (SSP) on receive can be used to resolve radar ambiguous measurements within a single burst, in contrast to the more conventional PRF Staggering approach which uses multiple bursts, each with a different pulse repetition frequency. In addition to reducing the total time needed to measure the target parameters unambiguously, the proposed waveform offers also some robustness against certain types of Electronic Counter Measures. The claims of the paper are validated by means of simulations as well as with a set of experimental measurements that were carried out at the University of Warsaw, which preliminarily confirm our findings.