976 research outputs found

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    Second generation of AVTIS FMCW millimeter wave radars for mapping volcanic terrain

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    The second generation AVTIS ground-based millimeter wave instruments designed for monitoring topography of volcanic lava domes are solid state 94 GHz FMCW rastered, real beam radars operating at ranges of up to ~7 km with a range resolution of ~2.5 m. Operating ten times faster than the prototype with reduced power consumption suitable for battery powered portable use as well as installation at a telemetered site under solar power, we examine their performance as tools for monitoring topography over time and report on the operational statistics both as a radar sensor and as a means of generating digital elevation maps.Publisher PD

    A review of Sarcocystis spp. shed by opossums (Didelphis spp.) in Brazil

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    Os gambás Sul-americanos são os hospedeiros definitivos de Sarcocystis falcatula, Sarcocystis neurona, Sarcocystis speeri e Sarcocystis lindsayi. Estas espécies de Sarcocystis são morfologicamente similares, mas podem ser distinguidas por sua patogenicidade e infectividade em hospedeiros intermediários (aves e camundongos imunodeficientes) e técnicas moleculares. Os gambás são animais silvestres e sinantrópicos e amplamente distribuídos no território nacional. Estudos anteriores demonstraram uma alta contaminação ambiental com esporocistos de S. neurona em diversas regiões brasileiras. Este artigo revisa informações sobre Sarcocystis spp. excretados por gambás e sua ocorrência no Brasil.South American opossums are the definitive hosts of Sarcocystis neurona, Sarcocystis falcatula, Sarcocystis speeri and Sarcocystis lindsayi. The sporocysts of these species of Sarcocystis are morphologically similar and methods like infectivity and pathogenicity for intermediate hosts (immunodeficient mice and psittacine birds) and molecular tools are used for identification. Opossums are synanthropic wild animals, and widely distributed in Brazilian territory. Previous studies have shown high environmental contamination with S. neurona sporocysts in several Brazilian regions. This paper reviews information on Sarcocystis spp. shed by various opossum species and its occurrence in Brazil

    The MILO Space Science Institute: Enabling New, Science-Focused Deep Space SmallSat Missions

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    •Initial activity: Design and development of inaugural mission concepts to achieve Decadal Survey-quality science relatively quickly to serve as a proof-of-concept for the MILO funding and management model •Inaugural mission costs significantly lower than those of NASA Discovery missions •Three inaugural small sat missions are being developed: two to explore Near-Earth Objects and one to explore the Moon •In discussions about MILO membership with more than 150 entities in 40 countrie

    Bringing home the trash: Do colony-based differences in foraging distribution lead to increased plastic ingestion in Laysan albatrosses?

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    When searching for prey, animals should maximize energetic gain, while minimizing energy expenditure by altering their movements relative to prey availability. However, with increasing amounts of marine debris, what once may have been ‘optimal’ foraging strategies for top marine predators, are leading to sub-optimal diets comprised in large part of plastic. Indeed, the highly vagile Laysan albatross (Phoebastria immutabilis) which forages throughout the North Pacific, are well known for their tendency to ingest plastic. Here we examine whether Laysan albatrosses nesting on Kure Atoll and Oahu Island, 2,150 km apart, experience different levels of plastic ingestion. Twenty two geolocators were deployed on breeding adults for up to two years. Regurgitated boluses of undigestable material were also collected from chicks at each site to compare the amount of plastic vs. natural foods. Chicks from Kure Atoll were fed almost ten times the amount of plastic compared to chicks from Oahu despite boluses from both colonies having similar amounts of natural food. Tracking data indicated that adults from either colony did not have core overlapping distributions during the early half of the breeding period and that adults from Kure had a greater overlap with the putative range of the Western Garbage Patch corroborating our observation of higher plastic loads at this colony. At-sea distributions also varied throughout the year suggesting that Laysan albatrosses either adjusted their foraging behavior according to constraints on time away from the nest or to variation in resources. However, in the non-breeding season, distributional overlap was greater indicating that the energy required to reach the foraging grounds was less important than the total energy available. These results demonstrate how a marine predator that is not dispersal limited alters its foraging strategy throughout the reproductive cycle to maximize energetic gain and how this has led to differences in plastic ingestion

    Submillimetre wave 3D imaging radar for security applications

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    There is ongoing worldwide interest in finding solutions to enhance the security of civilians at airports, borders and high risk public areas in ways which are safe, ethical and streamlined. One promising approach is to use submillimetre wave 3D imaging radar to detect concealed threats as it offers the advantages of high volumetric resolution (~1 cm3) with practically sized antennas (<0.5 m) such that even quite small objects can be resolved through clothing. The Millimetre Wave Group at the University of St Andrews has been developing submillimetre wave 3D imaging radars for security applications since 2007. A significant goal is to achieve near real-time frame rates of at least 10 Hz, to cope with dynamic scenes, over wide fields of view at short range with high pixel counts. We review the radar systems we have developed at 340 and 220 GHz and the underpinning technologies which we have employed to realise these goals.PostprintNon peer reviewe

    Hypogravity reduces trunk admittance and lumbar muscle activation in response to external perturbations

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    Reduced paraspinal muscle size and flattening of spinal curvatures have been documented after spaceflight. Assessment of trunk adaptations to hypogravity can contribute to develop specific countermeasures. In this study, parabolic flights were used to investigate spinal curvature and muscle responses to hypogravity. Data from five trials at 0.25g, 0.50g and 0.75g were recorded from six participants, positioned in a kneeling-seated position. During the first two trials, participants maintained a normal, upright posture. In the last three trials, small-amplitude perturbations were delivered in the anterior direction at the T10 level. Spinal curvature was estimated using motion capture cameras. Trunk displacement and contact force between the actuator and participant were recorded. Muscle activity responses were collected using intramuscular electromyography (iEMG) of the deep and superficial lumbar multifidus, iliocostalis lumborum, longissimus thoracis, quadratus lumborum, transversus abdominis, obliquus internus and obliquus externus muscles. The root mean square iEMG and the average spinal angles were calculated. Trunk admittance and muscle responses to perturbations were calculated as closed-loop frequency response functions. Compared with 0.75g, 0.25g resulted in: lower activation of the longissimus thoracis (P=0.002); lower responses of the superficial multifidus at low frequencies (P=0.043); lower responses of the superficial multifidus (P=0.029) and iliocostalis lumborum (P=0.043); lower trunk admittance (P=0.037) at intermediate frequencies; and stronger responses of the transversus abdominis at higher frequencies (p=0.032). These findings indicate that exposure to hypogravity reduces trunk admittance, partially compensated by weaker stabilizing contributions of the paraspinal muscles and coinciding with an apparent increase of the deep abdominal muscle activity
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