758 research outputs found
Excretion of low molecular weight, folin-positive metabolites by the female receptor mycelium, in response to mating.
Excretion of low molecular weight, folin-positive metabolites by the female receptor mycelium, in response to mating
Storm-Surge Flooding on the Yukon-Kuskokwim Delta, Alaska
Coastal regions of Alaska are regularly affected by intense storms of ocean origin, the frequency and intensity of which are expected to increase as a result of global climate change. The Yukon-Kuskokwim Delta (YKD), situated in western Alaska on the eastern edge of the Bering Sea, is one of the largest deltaic systems in North America. Its low relief makes it especially susceptible to storm-driven flood tides and increases in sea level. Little information exists on the extent of flooding caused by storm surges in western Alaska and its effects on salinization, shoreline erosion, permafrost thaw, vegetation, wildlife, and the subsistence-based economy. In this paper, we summarize storm flooding events in the Bering Sea region of western Alaska during 1913 – 2011 and map both the extent of inland flooding caused by autumn storms on the central YKD, using Radarsat-1 and MODIS satellite imagery, and the drift lines, using high-resolution IKONOS satellite imagery and field surveys. The largest storm surges occurred in autumn and were associated with high tides and strong (> 65 km hr-1) southwest winds. Maximum inland extent of flooding from storm surges was 30.3 km in 2005, 27.4 km in 2006, and 32.3 km in 2011, with total flood area covering 47.1%, 32.5%, and 39.4% of the 6730 km2 study area, respectively. Peak stages for the 2005 and 2011 storms were 3.1 m and 3.3 m above mean sea level, respectively—almost as high as the 3.5 m amsl elevation estimated for the largest storm observed (in November 1974). Several historically abandoned village sites lie within the area of inundation of the largest flood events. With projected sea level rise, large storms are expected to become more frequent and cover larger areas, with deleterious effects on freshwater ponds, non-saline habitats, permafrost, and landscapes used by nesting birds and local people.Les rĂ©gions cĂ´tières de l’Alaska sont souvent touchĂ©es par d’intenses tempĂŞtes d’origine ocĂ©anique. La frĂ©quence et l’intensitĂ© de ces tempĂŞtes devraient augmenter en raison du changement climatique qui s’opère Ă l’échelle mondiale. Le delta Yukon-Kuskokwim, dans l’ouest de l’Alaska, du cĂ´tĂ© est de la mer de BĂ©ring, est l’un des systèmes deltaĂŻques les plus imposants de l’AmĂ©rique du Nord. Son relief peu accidentĂ© le rend particulièrement susceptible aux marĂ©es montantes dĂ©coulant des tempĂŞtes et aux augmentations du niveau de la mer. Peu d’information existe au sujet de l’ampleur des inondations attribuables aux ondes de tempĂŞtes dans l’ouest de l’Alaska de mĂŞme que sur leurs effets en matière de saliniÂsation, d’érosion des berges, de dĂ©gel, de pergĂ©lisol, de vĂ©gĂ©tation, de faune et d’économie de subsistance. Dans cet article, nous rĂ©sumons les ondes de tempĂŞtes qui ont eu lieu dans la rĂ©gion de la mer de BĂ©ring de l’ouest de l’Alaska entre 1913 et 2011 et nous cartographions Ă l’aide de Radarsat-1 et de l’imagerie satellitaire MODIS l’étendue des inondations fluviales causĂ©es par les tempĂŞtes automnales dans le centre du delta Yukon-Kuskokwim, de mĂŞme que les lignes de dĂ©rive au moyen de l’imagerie satellitaire IKONOS Ă haute rĂ©solution et de levĂ©s sur le terrain. Les ondes de tempĂŞtes les plus importantes se sont produites Ă l’automne. Elles s’accompagnaient de marĂ©es hautes et de vents forts (> 65 km h-1) en provenance du sud-ouest. L’étendue maximale des inondations fluviales dĂ©coulant des ondes de tempĂŞtes a atteint 30,3 km en 2005, 27,4 km en 2006 et 32,3 km en 2011. Au total, la zone inondĂ©e couvrait respectivement 47,1 %, 32,5 % et 39,4 % de l’aire de 6 730 km2 visĂ©e par l’étude. Le niveau maximal des tempĂŞtes de 2005 et 2011 Ă©tait de 3,1 m et de 3,3 m au-dessus du niveau moyen de la mer, respectivement, ce qui est presque aussi Ă©levĂ© que la hauteur estimĂ©e de 3,5 m au-dessus du niveau moyen de la mer pour la plus grosse des tempĂŞtes observĂ©es (en novembre 1974). Plusieurs villages abandonnĂ©s au fil des ans se trouvent dans la zone touchĂ©e par les plus grandes inondations. Compte tenu de l’élĂ©vation projetĂ©e du niveau de la mer, la frĂ©quence des tempĂŞtes d’envergure devrait augmenter et les tempĂŞtes devraient couvrir des zones plus grandes, ce qui aura des effets dĂ©lĂ©tères sur les Ă©tangs d’eau douce, les habitats non salins, le pergĂ©lisol et les paysages dont se servent les oiseaux nicheurs et les gens de la rĂ©gion
Magnetic field hourly averages from the Rome-GSFC experiment aboard Helios 1 and Helio 2
Plots of all the hourly averages computed from the solar magnetic field measurements obtained during the mission are given separately for Helios 1 and Helios 2. The magnitude and the direction of the averaged field are plotted versus the number of solar rotations as seen from Helios, counted from launch
Neuronavigation and intraoperative imaging system in orbital tumor surgery: a review of recent literature
Orbit is a small complex anatomic space that contains important structures, ocular globe, extrinsic muscles, cranial nerves, blood vessels, fat, lacrimal gland. In presence of orbital tumors it is mandatory to use a surgical approach that allows to achieve an adequate surgical field while preserving neurological function. Neuronavigation is the set of computer-assisted technologies used to guide or "navigate” the edges of the tumor to allow the surgeon during resection or biopsy. This technology started with use of CT data to get some landmarks of human anatomy defined “targets” that could be readily used in surgery. Finally, the evolution of modern neuroimaging technologies such intraoperative CT and MRI boosted the surgery accuracy. In order to identify advantages and practical use of these technologies we performed a nonsystematic review of the current literature using the keywords “orbital tumor or orbital neoplasia or orbital mass or orbital lesion” and “neuronavigation or navigation” published in last 10 years. We evaluated 29 papers and we can conclude that navigation in orbital surgery helps to reduce surgical damage while at the same time, allowing a more radical tumor resection. CT and MRI scans are complementary in diagnosing and in intraoperative navigation allow the surgeon to avoid and preserve vital structures, particularly in a complex surgical procedure without real anatomical landmarks for intraoperative orientation. Future is going towards rapid changes and the integration with intraoperative procedures is carrying on to new technologies further our contemporary bounds
Planck Low Frequency Instrument: Beam Patterns
The Low Frequency Instrument on board the ESA Planck satellite is coupled to
the Planck 1.5 meter off-axis dual reflector telescope by an array of 27
corrugated feed horns operating at 30, 44, 70, and 100 GHz. We briefly present
here a detailed study of the optical interface devoted to optimize the angular
resolution (10 arcmin at 100 GHz as a goal) and at the same time to minimize
all the systematics coming from the sidelobes of the radiation pattern. Through
optical simulations, we provide shapes, locations on the sky, angular
resolutions, and polarization properties of each beam.Comment: On behalf of the Planck collaboration. 3 pages, 1 figure. Article
published in the Proceedings of the 2K1BC Experimental Cosmology at
millimetre wavelength
Towards a reappraisal of the phenotype of the cell wall deficient fz;sg;os-1 ( slime ) triple mutant of Neurospora crassa
Morphological mutants represent roughly 23% of seven hundred-odd distinct chromosomal loci of N. crassa, as listed by Perkins et al. (1982, Microbiol. Rev. 46:426). Probably the most radical phenotype among these strains is that of the fz;sg;os-1 ( slime ) triple mutant, which was isolated by Sterling Emerson (1963, Genetica 34:162) in a mutagenic experiment using an os-1 strain. The slime strain has been systematically referred to in the literature as a strain lacking cell wall and growing as protoplasts or plasmodium (Perkins et al. 1982). Through the years, the fragile slime structures were frequently used as a source of organelles (Martinoia et al. 1979. Arch. Microbiol. 120:31), membranes (Scarborough, 1975. J. Biol. Chem. 250:1106) or for the study of membrane-bound enzymes (Brooks et al. 1983. J. Biol. Chem. 258:13909). Slime spheroplasts practically never revert to hyphal morphology; thus, the causes for impaired cell wall synthesis were investigated and attributed either to the lack of glucan synthase activity (Leal-Morales and Ruiz-Herrera, 1985. Exp. Mycol 9:28) or to improper ultrastructural characteristics of the organelles responsible for chitin synthesis: the chitosomes (Martinez et al. 1989. Biochem. Biophys. Acta 990:45)
Dynamic validation of the Planck/LFI thermal model
The Low Frequency Instrument (LFI) is an array of cryogenically cooled
radiometers on board the Planck satellite, designed to measure the temperature
and polarization anisotropies of the cosmic microwave backgrond (CMB) at 30, 44
and 70 GHz. The thermal requirements of the LFI, and in particular the
stringent limits to acceptable thermal fluctuations in the 20 K focal plane,
are a critical element to achieve the instrument scientific performance.
Thermal tests were carried out as part of the on-ground calibration campaign at
various stages of instrument integration. In this paper we describe the results
and analysis of the tests on the LFI flight model (FM) performed at Thales
Laboratories in Milan (Italy) during 2006, with the purpose of experimentally
sampling the thermal transfer functions and consequently validating the
numerical thermal model describing the dynamic response of the LFI focal plane.
This model has been used extensively to assess the ability of LFI to achieve
its scientific goals: its validation is therefore extremely important in the
context of the Planck mission. Our analysis shows that the measured thermal
properties of the instrument show a thermal damping level better than
predicted, therefore further reducing the expected systematic effect induced in
the LFI maps. We then propose an explanation of the increased damping in terms
of non-ideal thermal contacts.Comment: Planck LFI technical papers published by JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/1748-022
Planck-LFI radiometers tuning
"This paper is part of the Prelaunch status LFI papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jinst"
This paper describes the Planck Low Frequency Instrument tuning activities
performed through the ground test campaigns, from Unit to Satellite Levels.
Tuning is key to achieve the best possible instrument performance and tuning
parameters strongly depend on thermal and electrical conditions. For this
reason tuning has been repeated several times during ground tests and it has
been repeated in flight before starting nominal operations. The paper discusses
the tuning philosophy, the activities and the obtained results, highlighting
developments and changes occurred during test campaigns. The paper concludes
with an overview of tuning performed during the satellite cryogenic test
campaign (Summer 2008) and of the plans for the just started in-flight
calibration.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in JINST. IOP Publishing Ltd is not responsible for
any errors or omissions in this version of the manuscript or any version
derived from it. The definitive publisher authenticated version is available
online at http://dx.doi.org/10.1088/1748-0221/4/12/T12013
Altered Immunoregulation in Rheumatoid Arthritis: The Role of Regulatory T Cells and Proinflammatory Th17 Cells and Therapeutic Implications
In recent years several studies investigated the role of T lymphocyte subpopulations in the pathogenesis of rheumatoid arthritis (RA). Pathogenic Th17 cells mediate pannus growth, osteoclastogenesis, and synovial neoangiogenesis; hence they are key players in the development of the disease. On the other hand, regulatory T (Treg) cells are a T cell subset whose peculiar function is to suppress autoreactive lymphocytes. The imbalance between Th17 and Treg cells has been identified as a crucial event in the pathogenesis of RA. In addition, the effects of currently employed RA therapeutic strategies on these lymphocyte subpopulations have been extensively investigated. This review article aims to discuss current knowledge on Treg and Th17 cells in RA and possible implications of their therapeutic targeting in this disorder
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