193 research outputs found
Portfolio Assessment in Liberal Arts Mathematics
This paper describes my efforts to incorporate problem-solving portfolios into my liberal arts mathematics course. I begin with a description of the components of the portfolios and the factors I consider in evaluating them. I then address some of the more significant obstacles I have encountered as well as what I consider to be among the major benefits. A selection from one studentâs portfolio is appended
Optimised access to user analysis data using the gLite DPM
The ScotGrid distributed Tier-2 now provides more that 4MSI2K and 500TB for LHC computing, which is spread across three sites at Durham, Edinburgh and Glasgow. Tier-2 sites have a dual role to play in the computing models of the LHC VOs. Firstly, their CPU resources are used for the generation of Monte Carlo event data. Secondly, the end user analysis data is distributed across the grid to the site's storage system and held on disk ready for processing by physicists' analysis jobs. In this paper we show how we have designed the ScotGrid storage and data management resources in order to optimise access by physicists to LHC data. Within ScotGrid, all sites use the gLite DPM storage manager middleware. Using the EGEE grid to submit real ATLAS analysis code to process VO data stored on the ScotGrid sites, we present an analysis of the performance of the architecture at one site, and procedures that may be undertaken to improve such. The results will be presented from the point of view of the end user (in terms of number of events processed/second) and from the point of view of the site, which wishes to minimise load and the impact that analysis activity has on other users of the system
Commodity study: Wool production by small-scale farmers
Small-scale wool production, especially in former bantustan areas, has the potential for significant expansion and ongoing and successful farmer support should be expanded. The small proportion of sheep and wool farmers in bantustan areas who are prepared to relocate to private land, preferably in nearby districts with similar physical and climatic characteristics, should be one priority for support through land redistribution programmes. The success or failure of expanded production and class mobility should be measured over the medium to long term, including over multiple generations and may depend on ongoing and effective support programmes. New employment opportunities are likely to be modest, especially as there is very limited processing of wool before export.
Farming for wool is extensive farming, optimally with low turnover but decent margins, compared to dairy farming which may also be extensive but is high in turnover with low margins. Net farm profit is a useful indicator of success or failure, rather than turnover. It may also be useful in defining emergent farmers. Net farm profit may be very different from household income as a measure of wealth/poverty and inequality. This is especially so in trust land areas where livestock and livestock products may constitute a small component of household income or a component used as savings or reserve capital for annual expenses, family events and emergencies
The Periodic Spectroscopic Variability of FU Orionis
FU Orionis systems are young stars undergoing outbursts of disc accretion and
where the optical spectrum contains lines associated with both the disc
photosphere and a wind component. Previous observations of the prototype FU
Orionis have suggested that the wind lines and the photospheric lines are
modulated with periods of 14.54 and 3.54 days respectively (Herbig et al.
2003). We have re-observed the system at higher spectral resolution, by
monitoring variations of optical line profiles over 21 nights in 2007 and have
found periods of 13.48 and 3.6 days in the wind and disc components consistent
with the above: this implies variability mechanisms that are stable over at
least a decade. In addition we have found: i) that the variations in the
photospheric absorption lines are confined to the blue wing of the line (around
-9km/s): we tentatively ascribe this to an orbiting hotspot in the disc which
is obscured by a disc warp during its receding phase. ii) The wind period is
manifested not only in blue-shifted Halpha absorption, but also in red-shifted
emission of Halpha and Hbeta, as well as in blue-shifted absorption of Na I D,
Li I and Fe II. iii) We find that the periodic modulation of blue-shifted
Halpha absorption at around -100km/s, is phase lagged with respect to
variations in the other lines by ~1.8days. This is consistent with a picture in
which variations at the wind base first affect chromospheric emission and then
low velocity blue-shifted absorption, followed - after a lag equal to the
propagation time of disturbances across the wind's acceleration region - by a
response in high velocity blue-shifted absorption. Such arguments constrain the
size of the acceleration region to ~10^12cm. We discuss possible mechanisms for
periodic variations within the innermost 0.1AU of the disc, including the
possibility that these variations indicate the presence of an embedded hot
Jupiter.Comment: 20 pages, 23 figures. Accepted for publication in MNRAS. See
http://www.ast.cam.ac.uk/~slp65/FUOripaperHRes.pdf for a pdf version of the
paper with high-resolution images; footnote added to the titl
Crew Exploration Vehicle Ascent Abort Overview
One of the primary design drivers for NASA's Crew Exploration Vehicle (CEV) is to ensure crew safety. Aborts during the critical ascent flight phase require the design and operation of CEV systems to escape from the Crew Launch Vehicle and return the crew safely to the Earth. To accomplish this requirement of continuous abort coverage, CEV ascent abort modes are being designed and analyzed to accommodate the velocity, altitude, atmospheric, and vehicle configuration changes that occur during ascent. The analysis involves an evaluation of the feasibility and survivability of each abort mode and an assessment of the abort mode coverage. These studies and design trades are being conducted so that more informed decisions can be made regarding the vehicle abort requirements, design, and operation. This paper presents an overview of the CEV, driving requirements for abort scenarios, and an overview of current ascent abort modes. Example analysis results are then discussed. Finally, future areas for abort analysis are addressed
The Stellar Population of h and chi Persei: Cluster Properties, Membership, and the Intrinsic Colors and Temperatures of Stars
(Abridged) From photometric observations of 47,000 stars and
spectroscopy of 11,000 stars, we describe the first extensive study of
the stellar population of the famous Double Cluster, h and Persei, down
to subsolar masses. Both clusters have E(B-V) 0.52--0.55 and dM =
11.8--11.85; the halo population, while more poorly constrained, likely has
identical properties. As determined from the main sequence turnoff, the
luminosity of M supergiants, and pre-main sequence isochrones, ages for h
Persei, Persei and the halo population all converge on 14 Myr.
From these data, we establish the first spectroscopic and photometric
membership lists of cluster stars down to early/mid M dwarfs. At minimum, there
are 5,000 members within 10' of the cluster centers, while the entire h
and Persei region has at least 13,000 and as many as 20,000
members. The Double Cluster contains 8,400 M of stars
within 10' of the cluster centers. We estimate a total mass of at least 20,000
M. We conclude our study by outlining outstanding questions regarding
the properties of h and Persei. From comparing recent work, we compile a
list of intrinsic colors and derive a new effective temperature scale for O--M
dwarfs, giants, and supergiants.Comment: 88 pages, many figures, Accepted for publication in The Astrophysical
Journal Supplements. Contact lead author for version with high-resolution
figure
Establishing Applicability of SSDs to LHC Tier-2 Hardware Configuration
Solid State Disk technologies are increasingly replacing high-speed hard
disks as the storage technology in high-random-I/O environments. There are
several potentially I/O bound services within the typical LHC Tier-2 - in the
back-end, with the trend towards many-core architectures continuing, worker
nodes running many single-threaded jobs and storage nodes delivering many
simultaneous files can both exhibit I/O limited efficiency. We estimate the
effectiveness of affordable SSDs in the context of worker nodes, on a large
Tier-2 production setup using both low level tools and real LHC I/O intensive
data analysis jobs comparing and contrasting with high performance spinning
disk based solutions. We consider the applicability of each solution in the
context of its price/performance metrics, with an eye on the pragmatic issues
facing Tier-2 provision and upgradesComment: 6 pages, 1 figure, 4 tables. Conference proceedings for CHEP201
Diurnal and stress-induced intra-hippocampal corticosterone rise attenuated in 11β-HSD1-deficient mice:a microdialysis study in young and aged mice
11βâHydroxysteroid dehydrogenase type 1 (11βâHSD1) locally regenerates active glucocorticoids from their inert forms thereby amplifying intracellular levels within target tissues including the brain. We previously showed greater increases in intraâhippocampal corticosterone (CORT) levels upon Yâmaze testing in aged wildâtype than in 11βâHSD1(â/â) mice coinciding with impaired and intact spatial memory, respectively. Here we examined whether ageing influences 11βâHSD1 regulation of CORT in the dorsal hippocampus under basal conditions during the diurnal cycle and following stress. Intraâhippocampal CORT levels measured by in vivo microdialysis in freely behaving wildâtype mice displayed a diurnal variation with peak levels in the evening that were significantly elevated with ageing. In contrast, the diurnal rise in intraâhippocampal CORT levels was greatly diminished in 11βâHSD1(â/â) mice and there was no rise with ageing; basal intraâhippocampal CORT levels were similar to wildâtype controls. Furthermore, a short (3 min) swim stress induced a longer lasting increase in intraâhippocampal CORT levels in wildâtype mice than in 11βâHSD1(â/â) mice despite no genotypic differences in elevation of plasma CORT. These data indicate that 11βâHSD1 activity contributes substantially to diurnal and stressâinduced increases in hippocampal CORT levels. This contribution is even greater with ageing. Thus, 11βâHSD1 inhibition may be an attractive target for treating cognitive impairments associated with stress or ageing
ScotGrid: Providing an Effective Distributed Tier-2 in the LHC Era
ScotGrid is a distributed Tier-2 centre in the UK with sites in Durham,
Edinburgh and Glasgow. ScotGrid has undergone a huge expansion in hardware in
anticipation of the LHC and now provides more than 4MSI2K and 500TB to the LHC
VOs. Scaling up to this level of provision has brought many challenges to the
Tier-2 and we show in this paper how we have adopted new methods of organising
the centres, from fabric management and monitoring to remote management of
sites to management and operational procedures, to meet these challenges. We
describe how we have coped with different operational models at the sites,
where Glagsow and Durham sites are managed "in house" but resources at
Edinburgh are managed as a central university resource. This required the
adoption of a different fabric management model at Edinburgh and a special
engagement with the cluster managers. Challenges arose from the different job
models of local and grid submission that required special attention to resolve.
We show how ScotGrid has successfully provided an infrastructure for ATLAS and
LHCb Monte Carlo production. Special attention has been paid to ensuring that
user analysis functions efficiently, which has required optimisation of local
storage and networking to cope with the demands of user analysis. Finally,
although these Tier-2 resources are pledged to the whole VO, we have
established close links with our local physics user communities as being the
best way to ensure that the Tier-2 functions effectively as a part of the LHC
grid computing framework..Comment: Preprint for 17th International Conference on Computing in High
Energy and Nuclear Physics, 7 pages, 1 figur
Sheep Updates 2006 - part 3
This session covers six papers from different authors:
GRAZING
1. Making better use of clover, Karen Venning and Andrew Thompson, Department of Primary Industries, Victoria
2. Grazing systems demonstration to optimise pasture utilisation and stocking rate, Mike Hyder, Sue-Ellen Shaw, Kelly Hill and Ron McTaggart, Department of Agriculture and Food Western Australia.
3. Know your audience to increase their rate of practice change - Lifetime Wool as an example, Gus Rose, Department of Agriculture and Food Western Australia, Carolyn Kabore, Kazresearch
REPRODUCTION
4. Lifetime Wool - Ewe Management Guidlines, Mandy Curnow, Department of Agriculture and Food Western Australia
5. Achieving the best reproductive performance from your hoggets, Kenyon PR, Morris ST, West DM, Perkins NR, Pinchbeck GL., Institute of Veterinary, Animal and Biomedical Sciences, Massey University, New Zealand.
6. Lifetime Wool: Twin futures, Dr Ralph Behrendt, Department of Primary Industries, Victori
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