545 research outputs found
High resolution observations of Cen A: Yellow and red supergiants in a region of jet-induced star formation?
We present the analysis of near infrared (NIR), adaptive optics (AO) Subaru
and archived HST imaging data of a region near the northern middle lobe (NML)
of the Centaurus A (Cen A) jet, at a distance of kpc north-east (NE)
from the center of NGC5128. Low-pass filtering of the NIR images reveals strong
-- above the background mean -- signal at the expected position of
the brightest star in the equivalent HST field. Statistical analysis of the NIR
background noise suggests that the probability to observe signal at
the same position, in three independent measurements due to stochastic
background fluctuations alone is negligible () and, therefore,
that this signal should reflect the detection of the NIR counterparts of the
brightest HST star. An extensive photometric analysis of this star yields
, visual-NIR, and NIR colors expected from a yellow supergiant (YSG) with
an estimated age Myr. Furthermore, the second and third
brighter HST stars are, likely, also supergiants in Cen A, with estimated ages
Myr and Myr, respectively. The ages of
these three supergiants are in good agreement with the ages of the young
massive stars that were previously found in the vicinity and are thought to
have formed during the later phases of the jet-HI cloud interaction that
appears to drive the star formation (SF) in the region for the past
Myr.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in Ap
Hepatic synthesis of carnitine from protein-bound trimethyl-lysine. Lysosomal digestion of methyl-lysine-labelled asialo-fetuin
The significance of sample mass in the analysis of steroid estrogens in sewage sludges and the derivation of partition coefficients in wastewaters
Optimization of an analytical method for determination of steroid estrogens, through minimizing sample size, resulted in recoveries >84%, with relative standard deviations <3% and demonstrated the significance of sample size on method performance. Limits of detection were 2.1–5.3 ng/g. Primary sludges had estrogen concentrations of up to one order of magnitude less than those found in biological sludges (up to 994 ng/g). However, partition coefficients were higher in primary sludges (except estriol), with the most hydrophobic compound (ethinylestradiol) exhibiting the highest Kp value, information which may be of value to those involved in modeling removal during wastewater treatment
Metagenomic survey of the microbiome of ancient Siberian permafrost and modern Kamchatkan cryosols
In the context of global warming, the melting of arctic permafrost raises the threat of a re-emergence of microorganisms some of which were shown to remain viable in ancient frozen soils for up to half a million years. In order to evaluate this risk, it is of interest to acquire a better knowledge of the composition of the microbial communities found in this understudied environment.
Here we present a metagenomics analysis of 12 soil samples from Russian Arctic and subarctic pristine areas: Chukotka, Yakutia, and Kamchatka, including 9 permafrost samples collected at various depths. These large datasets (9.2 1011 total bp) were assembled (525,313 contigs > 5kb), their encoded protein contents predicted, then used to perform taxonomical assignments of bacterial, archaeal, and eukaryotic organisms, as well as DNA viruses.
The various samples exhibited variable DNA contents and highly diverse taxonomic profiles showing no obvious relationship with their locations, depths or deposit ages. Bacteria represented the largely dominant DNA fraction (95%) in all samples, followed by archaea (3.2%), surprisingly little eukaryotes (0.5%), and viruses (0.4%).
Although no common taxonomic pattern was identified, the samples shared unexpected high frequencies of β-lactamase genes, almost 0.9 copy/bacterial genome. In addition of known environmental threats, the particularly intense warming of the Arctic might thus enhance the spread of bacterial antibiotic resistances, today's major challenge in public health. β-lactamases were also observed at high frequency in other types of soils, suggesting their general role in the regulation of bacterial populations
A Model for Solving the Optimal Water Allocation Problem in River Basins with Network Flow Programming When Introducing Non-Linearities
[EN] The allocation of water resources between different users is a traditional problem
in many river basins. The objective is to obtain the optimal resource distribution and the
associated circulating flows through the system. Network flow programming is a common
technique for solving this problem. This optimisation procedure has been used many times
for developing applications for concrete water systems, as well as for developing complete
decision support systems. As long as many aspects of a river basin are not purely linear, the
study of non-linearities will also be of great importance in water resources systems optimisation.
This paper presents a generalised model for solving the optimal allocation of water
resources in schemes where the objectives are minimising the demand deficits, complying
with the required flows in the river and storing water in reservoirs. Evaporation from
reservoirs and returns from demands are considered, and an iterative methodology is
followed to solve these two non-network constraints. The model was applied to the Duero
River basin (Spain). Three different network flow algorithms (Out-of-Kilter, RELAX-IVand
NETFLO) were used to solve the allocation problem. Certain convergence issues were
detected during the iterative process. There is a need to relate the data from the studied
systems with the convergence criterion to be able to find the convergence criterion which
yields the best results possible without requiring a long calculation time.We thank the Spanish Ministry of Economy and Competitivity (Comision Interministerial de Ciencia y Tecnologia, CICYT) for funding the projects INTEGRAME (contract CGL2009-11798) and SCARCE (program Consolider-Ingenio 2010, project CSD2009-00065). We also thank the European Commission (Directorate-General for Research & Innovation) for funding the project DROUGHT-R&SPI (program FP7-ENV-2011, project 282769). And last, but not least, to the Fundacion Instituto Euromediterraneo del Agua with the project "Estudio de Adaptaciones varias del modelo de optimizacion de gestiones de recursos hidricos Optiges".Haro Monteagudo, D.; Paredes Arquiola, J.; Solera Solera, A.; Andreu Álvarez, J. (2012). A Model for Solving the Optimal Water Allocation Problem in River Basins with Network Flow Programming When Introducing Non-Linearities. 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J Water Resour Plan Manag 135:48–55Kennington JL, Helgason RV (1980) Algorithms for network programming. John Wiley and Sons, New YorkKhaliquzzaman, Chander S (1997) Network flow programming model for multireservoir sizing. J Water Resour Plan Manag 123:15–21Kuczera G (1989) Fast Multireservoir Mulltiperiod Linear Programming Models. Water Resour Res 25:169–176Kuczera G (1993) Network linear programming codes for water-supply headworks modeling. J Water Resour Plan Manag 119:412–417Labadie J (2004) Optimal operation of multireservoir systems: state-of-the-art review. J Water Resour Plan Manag 130:93–111Labadie J (2006) MODSIM: river basin management decision support system. In: Singh W, Frevert D (eds) Watershed models. CRC, Boca Raton, pp 569–592Labadie J, Baldo M, Larson R (2000) MODSIM: decision support system for river basin management. Documentation and user manual. Dept. Of Civil Engineering, CSU, Fort CollinsManca A, Sechi G, Zuddas P (2010) Water supply network optimisation using equal flow algorithms. Water Resour Manag 24:3665–3678MMA (2000) Libro blanco del agua en España. Ministerio de Medio Ambiente, Secretaría general Técnica, Centro de PublicacionesMMA (2008) Confederación Hidrográfica del Duero. Memoria 2008. http://www.chduero.es/Inicio/Publicaciones/tabid/159/Default.aspx . Last accessed 25 June 2012Perera B, James B, Kularathna M (2005) computer software tool REALM for sustainable water allocation and management. J Environ Manag 77:291–300Rani D, Moreira M (2010) Simulation-optimization modeling: a survey and potential application in reservoir systems operation. Water Resour Manag 24:1107–1138Reca J, Roldán J, Alcaide M, López R, Camacho E (2001a) Optimisation model for water allocation in deficit irrigation systems I. Description of the model. Agric Water Manag 48:103–116Reca J, Roldán J, Alcaide M, López R, Camacho E (2001b) Optimisation model for water allocation in deficit irrigation systems II. Application to the Bembézar irrigation system. Agric Water Manag 48:117–132Sechi G, Zuddas P (2008) Multiperiod hypergraph models for water systems optimization. Water Resour Manag 22:307–320Sun H, Yeh W, Hsu N, Louie P (1995) Generalized network algorithm for water-supply-system optimization. J Water Resour Plan Manag 121:392–398Wurbs R (1993) Reservoir-system simulation and optimization models. J Water Resour Plan Manag 119:455–472Wurbs R (2005) Modeling river/reservoir system management, water allocation, and supply reliability. J Hydrol 300:100–113Yamout G, El-Fadel M (2005) An optimization approach for multi-sectoral water supply management in the greater Beirut area. Water Resour Manag 19:791–812Yates D, Sieber J, Purkey D, Hubert-Lee A (2005) WEAP21 – a demand-, priority-, and preference-driven water planning model. 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KELT-11b: A Highly Inflated Sub-Saturn Exoplanet Transiting the V=8 Subgiant HD 93396
We report the discovery of a transiting exoplanet, KELT-11b, orbiting the
bright () subgiant HD 93396. A global analysis of the system shows that
the host star is an evolved subgiant star with K,
, , log , and [Fe/H].
The planet is a low-mass gas giant in a day orbit,
with , , g cm, surface gravity log , and equilibrium temperature K. KELT-11 is the brightest known transiting exoplanet host
in the southern hemisphere by more than a magnitude, and is the 6th brightest
transit host to date. The planet is one of the most inflated planets known,
with an exceptionally large atmospheric scale height (2763 km), and an
associated size of the expected atmospheric transmission signal of 5.6%. These
attributes make the KELT-11 system a valuable target for follow-up and
atmospheric characterization, and it promises to become one of the benchmark
systems for the study of inflated exoplanets.Comment: 15 pages, Submitted to AAS Journal
KELT-20b: A Giant Planet With A Period Of P ~ 3.5 Days Transiting The V ~ 7.6 Early A Star HD 185603
We report the discovery of KELT-20b, a hot Jupiter transiting a early A star, HD 185603, with an orbital period of days. Archival and follow-up photometry, Gaia parallax, radial velocities, Doppler tomography, and AO imaging were used to confirm the planetary nature of KELT-20b and characterize the system. From global modeling we infer that KELT-20 is a rapidly rotating ( ) A2V star with an effective temperature of K, mass of , radius of , surface gravity of , and age of . The planetary companion has a radius of , a semimajor axis of au, and a linear ephemeris of . We place a upper limit of on the mass of the planet. Doppler tomographic measurements indicate that the planetary orbit normal is well aligned with the projected spin axis of the star ( ). The inclination of the star is constrained to , implying a three-dimensional spin–orbit alignment of . KELT-20b receives an insolation flux of , implying an equilibrium temperature of of ∼2250 K, assuming zero albedo and complete heat redistribution. Due to the high stellar , KELT-20b also receives an ultraviolet (wavelength nm) insolation flux of , possibly indicating significant atmospheric ablation. Together with WASP-33, Kepler-13 A, HAT-P-57, KELT-17, and KELT-9, KELT-20 is the sixth A star host of a transiting giant planet, and the third-brightest host (in V ) of a transiting planet
A Bright Short Period M-M Eclipsing Binary from the KELT Survey: Magnetic Activity and the Mass–Radius Relationship for M Dwarfs
We report the discovery of KELT J041621-620046, a moderately bright (J ~ 10.2) M-dwarf eclipsing binary system at a distance of 39 ± 3 pc. KELT J041621-620046 was first identified as an eclipsing binary using observations from the Kilodegree Extremely Little Telescope (KELT) survey. The system has a short orbital period of ~1.11 days and consists of components with and in nearly circular orbits. The radii of the two stars are and . Full system and orbital properties were determined (to ∼10% error) by conducting an EBOP (Eclipsing Binary Orbit Program) global modeling of the high precision photometric and spectroscopic observations obtained by the KELT Follow-up Network. Each star is larger by 17%–28% and cooler by 4%–10% than predicted by standard (non-magnetic) stellar models. Strong H α emission indicates chromospheric activity in both stars. The observed radii and temperature discrepancies for both components are more consistent with those predicted by empirical relations that account for convective suppression due to magnetic activity
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