12,604 research outputs found
Wireworm Control using Fodder Rape and Mustard â 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
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&
Charge-coupled devices with fast timing for astrophysics and space physics research
A charge coupled device is under development with fast timing capability (15 millisecond full frame readout, 30 microsecond resolution for measuring the time of individual pixel hits). The fast timing CCD will be used in conjunction with a CsI microfiber array or segmented scintillator matrix detector to detect x rays and gamma rays with submillimeter position resolution. The initial application will be in conjunction with a coded aperture hard x ray/gamma ray astronomy instrument. We describe the concept and the readout architecture of the device
The Rest-Frame Optical Spectrum of MS 1512-cB58
Moderate resolution, near-IR spectroscopy of MS1512-cB58 is presented,
obtained during commissioning of the the Near IR Spectrometer (NIRSPEC) on the
Keck II telescope. The strong lensing of this z=2.72 galaxy by the foreground
cluster MS1512+36 makes it the best candidate for detailed study of the
rest-frame optical properties of Lyman Break Galaxies.
A redshift of z=2.7290+/-0.0007 is inferred from the emission lines, in
contrast to the z=2.7233 calculated from UV observations of interstellar
absorption lines. Using the Balmer line ratios, we find an extinction of
E(B-V)=0.27. Using the line strengths, we infer an SFR=620+/-18 Msun/yr
(H_0=75, q_0=0.1, Lambda =0), a factor of 2 higher than that measured from
narrow-band imaging observations of the galaxy, but a factor of almost 4 lower
than the SFR inferred from the UV continuum luminosity. The width of the Balmer
lines yields a mass of M_vir=1.2x10^10 Msun. We find that the oxygen abundance
is 1/3 solar, in good agreement with other estimates of the metallicity.
However, we infer a high nitrogen abundance, which may argue for the presence
of an older stellar population.Comment: 14 pages, including 3 figures. Accepted for publication in ApJ
Letter
Peer mentorship and positive effects on student mentor and mentee retention and academic success
This study examined how the introduction of peer mentorship in an undergraduate health and social welfare programme at a large northern university affected student learning. Using an ethnographic case study approach, the study draws upon data collected from a small group of mentors and their mentees over a period of one academic year using interviews, reflective journals, assessment and course evaluation data.
Analysis of the data collected identified a number of key findings: peer mentorship improves assessment performance for both mentee and mentor; reduces stress and anxiety, enhances participation and engagement in the academic community, and adds value to student outcomes
- âŠ