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Multisite campaign on the open cluster M67 – III. δ Scuti pulsations in the blue stragglers
Bruntt, H.,Stello, D.,Suá,rez, J. C.,Arentoft, T.,Bedding, T. R.,Bouzid, M. Y.,Csubry, Z.,Dall, T. H.,Dind, Z. E.,Frandsen, S.,Gilliland, R. L.,Jacob, A. P.,Jensen, H. R.,Kang, Y. B.,Kim, S.-L. Blackwell Publishing Ltd 2007 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.378 No.4
<P>ABSTRACT</P><P>We have made an asteroseismic analysis of the variable blue stragglers in the open cluster M67. The data set consists of photometric time-series from eight sites using nine 0.6–2.1 m telescopes with a time-baseline of 43 d. In two stars, EW Cnc and EX Cnc, we detect the highest number of frequencies (41 and 26) detected in δ Scuti stars belonging to a stellar cluster, and EW Cnc has the second highest number of frequencies detected in any δ Scuti star. We have computed a grid of pulsation models that take the effects of rotation into account. The distribution of observed and theoretical frequencies shows that in a wide frequency range a significant fraction of the radial and non-radial low-degree modes are excited to detectable amplitudes. Despite the large number of observed frequencies we cannot constrain the fundamental parameters of the stars. To make progress we need to identify the degrees of some of the modes from either multicolour photometry or spectroscopy.</P>
Stello, D.,Bruntt, H.,Kjeldsen, H.,Bedding, T. R.,Arentoft, T.,Gilliland, R. L.,Nuspl, J.,Kim, S.-L.,Kang, Y. B.,Koo, J.-R.,Lee, J.-A.,Sterken, C.,Lee, C.-U.,Jensen, H. R.,Jacob, A. P.,Szabó,, R Blackwell Publishing Ltd 2007 Monthly notices of the Royal Astronomical Society Vol.377 No.2
<P>ABSTRACT</P><P>Measuring solar-like oscillations in an ensemble of stars in a cluster, holds promise for testing stellar structure and evolution more stringently than just fitting parameters to single field stars. The most-ambitious attempt to pursue these prospects was by Gilliland et al. who targeted 11 turn-off stars in the open cluster M67 (NGC 2682), but the oscillation amplitudes were too small (<20 μmag) to obtain unambiguous detections. Like Gilliland et al. we also aim at detecting solar-like oscillations in M67, but we target red giant stars with expected amplitudes in the range 50–500 μmag and periods of 1 to 8 h. We analyse our recently published photometry measurements, obtained during a six-week multisite campaign using nine telescopes around the world. The observations are compared with simulations and with estimated properties of the stellar oscillations. Noise levels in the Fourier spectra as low as 27 μmag are obtained for single sites, while the combined data reach 19 μmag, making this the best photometric time series of an ensemble of red giant stars. These data enable us to make the first test of the scaling relations (used to estimate frequency and amplitude) with an homogeneous ensemble of stars. The detected excess power is consistent with the expected signal from stellar oscillations, both in terms of its frequency range and amplitude. However, our results are limited by apparent high levels of non-white noise, which cannot be clearly separated from the stellar signal.</P>
Jacob P. Walsh,Natasha DesRochers,Justin B. Renaud,Keith A. Seifert,Ken K.-C. Yeung,Mark W. Sumarah 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.1
Background: It is estimated that 20-30% of ginseng crops in Canada are lost to root rot each harvest. This disease is commonly caused by fungal infection with Ilyonectria, previously known as Cylindrocarpon. Previous reports have linked the virulence of fungal disease to the production of siderophores, a class of small-molecule iron chelators. However, these siderophores have not been identified in Ilyonectria. Methods: High-resolution LC-MS/MS was used to screen Ilyonectria and Cylindrocarpon strain extracts for secondary metabolite production. These strains were also tested for their ability to cause root rot in American ginseng and categorized as virulent or avirulent. The differences in detected metabolites between the virulent and avirulent strains were compared with a focus on siderophores. Results: For the first time, a siderophore N,N",N""-triacetylfusarinine C (TAFC) has been identified in Ilyonectria, and it appears to be linked to disease virulence. Siderophore production was suppressed as the concentration of iron increased, which is in agreement with previous reports. Conclusion: The identification of the siderophore produced by Ilyonectria gives us further insight into the root rot disease that heavily affects ginseng crop yields. This research identifies a molecular pathway previously unknown for ginseng root rot and could lead to new disease treatment options.
Multisite campaign on the open cluster M67 – I. Observations and photometric reductions
Stello, D.,Arentoft, T.,Bedding, T. R.,Bouzid, M. Y.,Bruntt, H.,Csubry, Z.,Dall, T. H.,Dind, Z. E.,Frandsen, S.,Gilliland, R. L.,Jacob, A. P.,Jensen, H. R.,Kang, Y. B.,Kim, S.-L.,Kiss, L. L.,Kjeldsen, Blackwell Publishing Ltd 2006 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.373 No.3
<P>ABSTRACT</P><P>We report on an ambitious multisite campaign aimed at detecting stellar variability, particularly solar-like oscillations, in the red giant stars in the open cluster M67 (NGC 2682). During the six-week observing run, which comprised 164 telescope nights, we used nine 0.6-m to 2.1-m class telescopes located around the world to obtain uninterrupted time series photometry. We outline here the data acquisition and reduction, with emphasis on the optimization of the signal-to-noise ratio of the low-amplitude (50–500 μmag) solar-like oscillations. This includes a new and efficient method for obtaining the linearity profile of the CCD response at ultrahigh precision (∼10 parts per million). The noise in the final time series is 0.50 mmag per minute integration for the best site, while the noise in the Fourier spectrum of all sites combined is 20 μmag. In addition to the red giant stars, this data set proves to be very valuable for studying high-amplitude variable stars such as eclipsing binaries, W UMa systems and δ Scuti stars.</P>
Digital Soil Mapping by Hyperspectral Imagery for Environmental Modelling in Mediterranean Regions
Lagacherie, P.,Gomez, C.,Bacha, S.,Ben Mechlia, M.,Baret, F.,Blanca, Y.,Coulouma,Derouiche, M.G.,Follain, S.,Hamrouni, H.,Jacob, F.,Le Bissonnais, Y.,Le Martret, H.,Masmoudi, M.M.,McBratney, A.B.,Mina 한국토양비료학회 2009 한국토양비료학회 학술발표회 초록집 Vol.2009 No.10
James D. St. Louis,이철,Hiromi Kurosawa,Richard A. Jonas,Sakamoto Kisaburo,Christo I. Tchervenkov,Jeffery P. Jacobs,James K. Kirklin 대한흉부외과학회 2018 Journal of Chest Surgery (J Chest Surg) Vol.51 No.1
More than a decade has elapsed since the historic inaugural meeting of the World Society for Pediatric and Congenital Heart Surgery (WSPCHS). The leaders and participants of this event were motivated and inspired by the prospect of a new era of global communication in the field of congenital heart disease. Their mission, galvanized by the ratification of the society’s constitution, directed new members to promulgate efforts to “promote the highest quality of comprehensive cardiac care to all patients with congenital heart disease across the globe,” with a message that would be realized for decades to come [1].
Surface ozone background in the United States: Canadian and Mexican pollution influences
Wang, H.,Jacob, D.J.,Le Sager, P.,Streets, D.G.,Park, R.J.,Gilliland, A.B.,van Donkelaar, A. Pergamon Press ; Elsevier [distribution] 2009 Atmospheric environment Vol.43 No.6
We use a global chemical transport model (GEOS-Chem) with 1<SUP>o</SUP>x1<SUP>o</SUP> horizontal resolution to quantify the effects of anthropogenic emissions from Canada, Mexico, and outside North America on daily maximum 8-hour average ozone concentrations in US surface air. Simulations for summer 2001 indicate mean North American and US background concentrations of 26+/-8ppb and 30+/-8ppb, as obtained by eliminating anthropogenic emissions in North America vs. in the US only. The US background never exceeds 60ppb in the model. The Canadian and Mexican pollution enhancement averages 3+/-4ppb in the US in summer but can be occasionally much higher in downwind regions of the northeast and southwest, peaking at 33ppb in upstate New York (on a day with 75ppb total ozone) and 18ppb in southern California (on a day with 68ppb total ozone). The model is successful in reproducing the observed variability of ozone in these regions, including the occurrence and magnitude of high-ozone episodes influenced by transboundary pollution. We find that exceedances of the 75ppb US air quality standard in eastern Michigan, western New York, New Jersey, and southern California are often associated with Canadian and Mexican pollution enhancements in excess of 10ppb. Sensitivity simulations with 2020 emission projections suggest that Canadian pollution influence in the Northeast US will become comparable in magnitude to that from domestic power plants.
Development of Symmetrical Fault Detection During Power Swing Based on Entropy
Devi R.,Kirthika A.,Divya Priyadharshini M.,Ladha Akash,Anju A.,Rajesh Kumar T.,Ganesh Prabhu S.,Varghese Lijo Jacob,Santhosh P. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3
This paper proposes the new technique for detecting symmetrical faults occurred during power swing. The proposed technique is simulated for the protection of two machine system, distribution system with distributed generation and WSCC 9-bus system in Matlab. Symmetrical fault detection during power swing is a critical issue. Hence, in this paper, modifi ed weighted wavelet packet entropy technique is proposed to detect symmetrical fault during power swing. This entropy criterion is applied to wavelet packet coeffi cients to enhance the energy of fault signals and to reduce the vector size of the wavelet packet transform coeffi cients. This technique provides better results irrespective of various fault locations, fault inception angle and power swing frequencies. This technique is compared with conventional scheme and the results are tabulated. Moreover, this technique is also able to detect asymmetrical faults with high impedance during power swing. Mathematical derivation support system performance through simulation.
Yihui Wang,Joseph P. Hoffmann,Chau-Wen Chou,Kerstin Höner zu Bentrup,Joseph A. Fuselier,Jacob P. Bitoun,William C. Wimley,Lisa A. Morici 한국미생물학회 2020 The journal of microbiology Vol.58 No.7
Gram-negative bacteria secrete outer membrane vesicles (OMVs) that play critical roles in intraspecies, interspecies, and bacteria-environment interactions. Some OMVs, such as those produced by Pseudomonas aeruginosa, have previously been shown to possess antimicrobial activity against competitor species. In the current study, we demonstrate that OMVs from Burkholderia thailandensis inhibit the growth of drug-sensitive and drug-resistant bacteria and fungi. We show that a number of antimicrobial compounds, including peptidoglycan hydrolases, 4-hydroxy-3-methyl-2-(2-nonenyl)- quinoline (HMNQ) and long-chain rhamnolipid are present in or tightly associate with B. thailandensis OMVs. Furthermore, we demonstrate that HMNQ and rhamnolipid possess antimicrobial and antibiofilm properties against methicillin- resistant Staphylococcus aureus (MRSA). These findings indicate that B. thailandensis secretes antimicrobial OMVs that may impart a survival advantage by eliminating competition. In addition, bacterial OMVs may represent an untapped resource of novel therapeutics effective against biofilm- forming and multidrug-resistant organisms.