15,243 research outputs found
Wireworm Control using Fodder Rape and Mustard – evaluating the use of brassica green manures for the control of wireworm (Agriotes spp.) in organic crops
In a field experiment at ADAS Pwllpeiran in 2001, brassica green manures were grown for 6 weeks and dug in before planting King Edward potatoes, to see if they suppressed wireworm in the crop. There was a trend for potatoes grown after mustard to suffer less damage from both wireworms and slugs than potatoes grown after fodder rape or no green manure, but the differences were not significant. Further trials, with longer green manuring periods, are needed to establish if there is a benefit, and whether the breakdown products of brassica green manures are toxic to wireworms
Close pairs of galaxies with different activity levels
We selected and studied 180 pairs with dV < 800 km/s and Dp < 60 kpc
containing Markarian (MRK) galaxies to investigate the dependence of galaxies'
integral parameters, star-formation (SF) and active galactic nuclei (AGN)
properties on kinematics of pairs, their structure and large-scale
environments. Projected radial separation Dp and perturbation level P are
better measures of interaction strength than dV. The latter correlates with the
density of large-scale environment and with the morphologies of galaxies. Both
galaxies in a pair are of the same nature, the only difference is that MRK
galaxies are usually righter than their neighbors. Specific star formation
rates (SSFR) of galaxies in pairs with smaller Dp or dV is in average 0.5 dex
higher than that of galaxies in pairs with larger Dp or dV. Closeness of a
neighbor with the same and later morphological type increases the SSFR, while
earlier-type neighbors do not increase SSFR. Major interactions/mergers trigger
SF and AGN more effectively than minor ones. The fraction of AGNs is higher in
more perturbed pairs and pairs with smaller Dp. AGNs typically are in stronger
interacting systems than star-forming and passive galaxies. There are
correlations of both SSFRs and spectral properties of nuclei between pair
members.Comment: 4 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:1310.024
Close neighbors of Markarian galaxies. II. Statistics and discussions
According to the database from the first paper, we select 180 pairs with dV <
800 km/s and Dp < 60 kpc containing Markarian (MRK) galaxies. We study the
dependence of galaxies integral parameters, star-formation (SF) and active
galactic nuclei (AGN) properties on kinematics of pairs, their structure and
large-scale environments. Following main results were obtained: projected
radial separation Dp between galaxies correlates with the perturbation level P
of the pairs. Both parameters do not correlate with line-of-sight velocity
difference dV of galaxies. Dp and P are better measures of interaction strength
than dV. The latter correlates with the density of large-scale environment and
with the morphologies of galaxies. Both galaxies in a pair are of the same
nature, the only difference is that MRK galaxies are usually brighter than
their neighbors in average by 0.9 mag. Specific star formation rates (SSFR) of
galaxies in pairs with smaller Dp or dV is in average 0.5 dex higher than that
of galaxies in pairs with larger Dp or dV. Closeness of a neighbor with the
same and later morphological type increases the SSFR, while earlier-type
neighbors do not increase SSFR. Major interactions/mergers trigger SF and AGN
more effectively than minor ones. The fraction of AGNs is higher in more
perturbed pairs and pairs with smaller Dp. AGNs typically are in stronger
interacting systems than star-forming and passive galaxies. There are
correlations of both SSFRs and spectral properties of nuclei between pair
members.Comment: 13 pages, 8 figures, 2 table
The GSC-II-based survey of ancient cool white dwarfs I. The sample of spectroscopically confirmed WDs
The GSC-II white dwarf survey was designed to identify faint and high proper
motion objects, which we used to define a new and independent sample of cool
white dwarfs. With this survey we aim to derive new constraints on the halo
white dwarf space density. Also, these data can provide information on the age
of thick disk and halo through the analysis of the luminosity function. On the
basis of astrometric and photometric parameters, we selected candidates with mu
> 0.28 as/yr and R_F > 16 in an area of 1150 square degrees. Then, we separated
white dwarfs from late type dwarfs and subdwarfs by means of the reduced proper
motion diagram. Finally, spectroscopic follow-up observations were carried out
to confirm the white dwarf nature of the selected candidates. We found 41 white
dwarfs of which 24 are new discoveries. Here we present the full sample and for
each object provide positions, absolute proper motions, photometry, and
spectroscopy.Comment: 14 pages, 7 figures, submitted to A&
What drives me there? The interplay of socio-psychological gratification and consumer values in social media brand engagement
The social behavioral perspective is under-researched in the extant literature. This hinders the holistic understanding of social media brand engagement. This study examines the interplay of socio-psychological gratification variables (perceived homophily, perceived critical mass, and self-status seeking) and consumer values (personal, interpersonal, and fun) on consumer participation in social media brand engagement. The conceptual model in this study is situated on the principles of Uses and Gratifications, Critical Mass, Homophily, and Values theories. Based on an online survey of 713 Facebook users, we examine the model using structural equation modeling (with Amos 23.0). The analysis disclosed insights on the interplay of motivational factors that underlie social media brand engagement. Our findings suggest that socio-psychological gratification variables (perceived homophily, perceived critical mass, and self-status seeking) drive consumers’ engagement with brand pages and brand communities on social media. This relationship is strengthened by the consumer values. These insights serve as an important basis for researchers and practitioners to understand social media brand engagement and its outcomes
Using AI/expert system technology to automate planning and replanning for the HST servicing missions
This paper describes a knowledge-based system that has been developed to automate planning and scheduling for the Hubble Space Telescope (HST) Servicing Missions. This new system is the Servicing Mission Planning and Replanning Tool (SM/PART). SM/PART has been delivered to the HST Flight Operations Team (FOT) at Goddard Space Flight Center (GSFC) where it is being used to build integrated time lines and command plans to control the activities of the HST, Shuttle, Crew and ground systems for the next HST Servicing Mission. SM/PART reuses and extends AI/expert system technology from Interactive Experimenter Planning System (IEPS) systems to build or rebuild time lines and command plans more rapidly than was possible for previous missions where they were built manually. This capability provides an important safety factor for the HST, Shuttle and Crew in case unexpected events occur during the mission
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