983 research outputs found
Krüger's Final Camp in Arctic Canada?
On 3 July 1999, John England, Art Dyke, and undergraduate student Michelle Laurie were surveying raised marine shorelines on Axel Heiberg Island halfway between Cape Southwest and the mouth of Surprise Fiord. During this work, they discovered a site with objects that appeared to be "of considerable antiquity." ... Only the compass and the transit were collected for preservation and identification. Protruding through the surface sand was evidence of additional material, including what appeared to be tent canvas, as well as printed material and a shirt (or long underwear) with label of German origin. ... As both England and Dyke are well acquainted with the history of Arctic exploration, they began to consider who might have left the instrument, and under what circumstances, given its evident value. ... The abandoned samples clearly identified the site as a geological camp. The abandonment of specimens would be consistent with a team in some difficulty. ... The 1999 find described here now provides the best evidence concerning the probable fate of Hans Krüger and his team. The German label on the partially buried clothing, the fragment that appears to be tent canvas, the old-style canister, the small pile of rock samples, and most significantly, the evidence gleaned from the small transit, point to new evidence concerning this 70-year-old Arctic mystery. Why would one abandon such easily transported and important possessions that would constitute the very heart of the scientific expedition? The overriding impression that one is left with at this sparse site is its abandonment under duress. The fact that so few provisions remained, and that the tent itself many have been destroyed, suggests that the camp may have suffered a late spring snowstorm that buried what remained, and the explorers had no time or energy left to excavate it before escaping eastward. Regardless, if the site is Krüger's, then his team made it several hundred kilometres farther back on their return journey than was previously thought. Sadly, Krüger's fiancé and mother never had conclusive evidence of their loss, and their anguish is revealed in letters sent to Krüger via the RCMP in 1931, now preserved in the Library and Archives Canada. His fiancé never married and tragically committed suicide in 1946. We hope that the planned archeological survey of the subsurface and the snow-filled gullies adjacent to the site will help clarify what we have presented here, further confirming that this is Krüger's final camp. Since scientific surveys, including ours, have been so widely conducted along the coastlines to the east that lead into and through Eureka Sound, it is unlikely that any subsequent camp will be found
Ultrasonic Stimulation of Mouse Skin Reverses the Healing Delays in Diabetes and Aging by Activation of Rac1
Chronic skin-healing defects are one of the leading challenges to lifelong well-being, affecting 2–5% of populations. Chronic wound formation is linked to age and diabetes and frequently leads to major limb amputation. Here we identify a strategy to reverse fibroblast senescence and improve healing rates. In healthy skin, fibronectin activates Rac1 in fibroblasts, causing migration into the wound bed, and driving wound contraction. We discover that mechanical stimulation of the skin with ultrasound can overturn healing defects by activating a calcium/CamKinaseII/Tiam1/Rac1 pathway that substitutes for fibronectin-dependent signaling and promotes fibroblast migration. Treatment of diabetic and aged mice recruits fibroblasts to the wound bed and reduces healing times by 30%, restoring healing rates to those observed in young, healthy animals. Ultrasound treatment is equally effective in rescuing the healing defects of animals lacking fibronectin receptors, and can be blocked by pharmacological inhibition of the CamKinaseII pathway. Finally, we discover that the migration defects of fibroblasts from human venous leg ulcer patients can be reversed by ultrasound, demonstrating that the approach is applicable to human chronic samples. By demonstrating that this alternative Rac1 pathway can substitute for that normally operating in the skin, we identify future opportunities for management of chronic wounds
A Hierarchical Hybrid Architecture for Mission-Oriented Robot Control
The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-03413-3_26In this work is presented a general architecture for a multi
physical agent network system based on the coordination and the behaviour
management. The system is organised in a hierarchical structure
where are distinguished the individual agent actions and the collective
ones linked to the whole agent network. Individual actions are also organised
in a hybrid layered system that take advantages from reactive and
deliberative control. Sensing system is involved as well in the behaviour
architecture improving the information acquisition performance.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness under the CICYT project Mission Based Control (COBAMI): DPI2011-28507-C02-02, under coordinated project High Integrity Partitioned Embedded Systems (Hi-PartES): TIN2011-28567-C03-03, and under the collaborative research project supported by the European Union MultiPARTES Project: FP7-ICT 287702. 2011-14.Muñoz Alcobendas, M.; Munera Sánchez, E.; Blanes Noguera, F.; Simó Ten, JE. (2013). A Hierarchical Hybrid Architecture for Mission-Oriented Robot Control. En ROBOT2013: First Iberian Robotics Conference: Advances in Robotics, Vol. 1. Springer. 363-380. https://doi.org/10.1007/978-3-319-03413-3_26S363380Aragues, R.: Consistent data association in multi-robot systems with limited communications. 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In: Fourth International System on Intelligent Robotics Systems, Lisboa, Portugal (1996)McGann, C., Py, F., Rajan, K., Thomas, H., Henthorn, R., McEwen, R.: A deliberative architecture for auv control. In: IEEE International Conference on Robotics and Automation, ICRA 2008, pp. 1049–1054. IEEE (2008)Munera, E., Muñoz, M., Simó, J., Blanes, F.: Humanoid Robot Self-Location In SPL League. In: Comité Español de Automática (CEA), XXXIII Jornadas de Automatica, 797–804 (2012)Proetzsch, M., Luksch, T., Berns, K.: Development of complex robotic systems using the behavior-based control architecture iB2C. Robotics and Autonomous Systems 58(1), 46–67 (2010)Qiu, D.: Supervisory control of fuzzy discrete event systems: a formal approach. IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics 35(1), 72–88 (2005)Aladebaran Robotics. NAO Software Documentation 1.12. 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Magnetothemopower study of quasi two-dimensional organic conductor -(BEDT-TTF)KHg(SCN)
We have used a low-frequency magneto-thermopower (MTEP) method to probe the
high magnetic field ground state behavior of
-(BEDT-TTF)KHg(SCN) along all three principal crystallographic
axes at low temperatures. The thermopower tensor coefficients (
and ) have been measured to 30 T, beyond the anomalous low temperature,
field-induced transition at 22.5 T. We find a significant anisotropy in the
MTEP signal, and also observe large quantum oscillations associated with the de
Haas - van Alphen effect. The anisotropy indicates that the ground state
properties are clearly driven by mechanisms that occur along specific
directions for the in-plane electronic structure. Both transverse and
longitudinal magnetothermopower show asymptotic behavior in field, which can be
explained in terms of magnetic breakdown of compensated closed orbits.Comment: 9 pages, 10 figure
The X10 Flare on 2003 October 29: Triggered by Magnetic Reconnection between Counter-Helical Fluxes?
Vector magnetograms taken at Huairou Solar Observing Station (HSOS) and Mees
Solar Observatory (MSO) reveal that the super active region (AR) NOAA 10486 was
a complex region containing current helicity flux of opposite signs. The main
positive sunspots were dominated by negative helicity fields, while positive
helicity patches persisted both inside and around the main positive sunspots.
Based on a comparison of two days of deduced current helicity density,
pronounced changes were noticed which were associated with the occurrence of an
X10 flare that peaked at 20:49 UT, 2003 October 29. The average current
helicity density (negative) of the main sunspots decreased significantly by
about 50. Accordingly, the helicity densities of counter-helical patches
(positive) were also found to decay by the same proportion or more. In
addition, two hard X-ray (HXR) `footpoints' were observed by the Reuven Ramaty
High Energy Solar Spectroscopic Imager (RHESSI} during the flare in the 50-100
keV energy range. The cores of these two HXR footpoints were adjacent to the
positions of two patches with positive current helicity which disappeared after
the flare. This strongly suggested that the X10 flare on 2003 Oct. 29 resulted
from reconnection between magnetic flux tubes having opposite current helicity.
Finally, the global decrease of current helicity in AR 10486 by ~50% can be
understood as the helicity launched away by the halo coronal mass ejection
(CME) associated with the X10 flare.Comment: Solar Physics, 2007, in pres
Modeling of droplet generation in a top blowing steelmaking process
Quantification of metal droplets ejected due to impinging gas jet on the surface of liquid metal is an important parameter for the understanding and for the modeling of the refining kinetics of reactions in slag-metal emulsion zone. In the present work, a numerical study has been carried out to critically examine the applicability of droplet generation rate correlation previously proposed by Subagyo et al. on the basis of dimensionless blowing number (N B). The blowing number was re-evaluated at the impingement point of jet with taking into account the temperature effect of change in density and velocity of the gas jet. The result obtained from the work shows that the modified blowing number N B,T at the furnace temperature of 1873 K (1600 °C) is approximately double in magnitude compared to N B calculated by Subagyo and co-workers. When N B,T has been employed to the Subagyo’s empirical correlation for droplet generation, a wide mismatch is observed between the experimental data obtained from cold model and hot model experiments. The reason for this large deviation has been investigated in the current study, and a theoretical approach to estimate the droplet generation rate has been proposed. The suitability of the proposed model has been tested by numerically calculating the amount of metals in slag. The study shows that the weight of metals in emulsion falls in the range of 0 to 21 wt pct of hot metal weight when droplet generation rate has been calculated at ambient furnace temperature of 1873 K (1600 °C)
Transfer learning for galaxy morphology from one survey to another
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.Deep Learning (DL) algorithms for morphological classification of galaxies have proven very successful, mimicking (or even improving) visual classifications. However, these algorithms rely on large training samples of labelled galaxies (typically thousands of them). A key question for using DL classifications in future Big Data surveys is how much of the knowledge acquired from an existing survey can be exported to a new dataset, i.e. if the features learned by the machines are meaningful for different data. We test the performance of DL models, trained with Sloan Digital Sky Survey (SDSS) data, on Dark Energy survey (DES) using images for a sample of 5000 galaxies with a similar redshift distribution to SDSS. Applying the models directly to DES data provides a reasonable global accuracy ( 90%), but small completeness and purity values. A fast domain adaptation step, consisting in a further training with a small DES sample of galaxies (500-300), is enough for obtaining an accuracy > 95% and a significant improvement in the completeness and purity values. This demonstrates that, once trained with a particular dataset, machines can quickly adapt to new instrument characteristics (e.g., PSF, seeing, depth), reducing by almost one order of magnitude the necessary training sample for morphological classification. Redshift evolution effects or significant depth differences are not taken into account in this study.Peer reviewedFinal Accepted Versio
Microbiological profile of donor corneas stored for tectonic transplantation purposes in rabbits
DES15E2mlf: a spectroscopically confirmed superluminous supernova that exploded 3.5 Gyr after the big bang
We present the Dark Energy Survey (DES) discovery of DES15E2mlf, the most distant superluminous supernova (SLSN) spectroscopically confirmed to date. The light curves and Gemini spectroscopy of DES15E2mlf indicate that it is a Type I superluminous supernova (SLSN-I) at z = 1.861 (a lookback time of ∼10 Gyr) and peaking at MAB = −22.3 ± 0.1 mag. Given the high redshift, our data probe the rest-frame ultraviolet (1400–3500 Å) properties of the SN, finding velocity of the C III feature changes by ∼5600 km s−1 over 14 d around maximum light. We find the host galaxy of DES15E2mlf has a stellar mass of 3.5+3.6 −2.4 × 109 M, which is more massive than the typical SLSN-I host galaxy
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