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2D3D2D: a diagnostic approach to textile and fashion research practice
In the School of Art and Design, at Nottingham Trent University, a range of research methods and practices have developed through PhD and post doctoral study in relation to printed textile design and new technology. Individual research projects have addressed pattern (Bunce 1993); photographic imagery (Briggs 1997); colour (Leak 2001); non-repeating pattern (Carlisle 2003) and 2D/3D (Townsend 2003). Post-doctoral research (Briggs-Goode & Bunce 2001) and Townsend's research into 2D/3D informed a group project and exhibition Transforming Shape (2004). The outcomes created by Gillian Bunce, Amanda Briggs-Goode, Gillian Bunce, Rosemary Goulding and Katherine Townsend explored the relationships between innovative surface imagery and three-dimensional prototypes, based on the simple geometric forms of square, rectangle and circle
Moderate temperature detector development
P-side backside reflecting constant, photodiode characterization, and photodiode diffusion and G-R currents were investigated in an effort to develop an 8 m to 12 m infrared quantum detector using mercury cadmium telluride. Anodization, phosphorus implantation, and the graded band gap concept were approaches considered for backside formation. Variable thickness diodes were fabricated with a back surface anodic oxide to investigate the effect of this surface preparation on the diffusion limited zero bias impedance. A modeling technique was refined to thoroughly model diode characteristics. Values for the surface recombination velocity in the depletion region were obtained. These values were improved by implementing better surface damage removal techniques
An XMM-Newton observation of the young open cluster NGC 2547: coronal activity at 30 Myr
We report XMM-Newton observations of the young open cluster NGC 2547 which
allow us to characterise coronal activity in solar-type stars at an age of 30
Myr. X-ray emission peaks among G-stars at luminosities (0.3-3keV) of
Lx~10^{30.5} erg/s and declines to Lx<=10^{29.0} erg/s among M-stars. Coronal
spectra show evidence for multi-temperature differential emission measures and
low coronal metal abundances (Z~0.3). The G- and K-type stars follow the same
relationship between X-ray activity and Rossby number established in older
clusters and field stars, although most solar-type stars in NGC 2547 exhibit
saturated/super-saturated X-ray activity levels. Median levels of Lx and
Lx/Lbol in the solar-type stars of NGC 2547 are similar to T-Tauri stars of the
Orion Nebula cluster (ONC), but an order of magnitude higher than in the older
Pleiades. The spread in X-ray activity levels among solar-type stars in NGC
2547 is much smaller than in older or younger clusters. Coronal temperatures
increase with Lx, Lx/Lbol and surface X-ray flux. Active solar-type stars in
NGC 2547 have coronal temperatures between those in the ONC and the most active
older ZAMS stars. A flaring rate (for total flare energies [0.3-3keV] >10^{34}
erg) of 1 every 350^{+350}_{-120} ks was found for solar-type stars, similar to
rates found in the ONC and Pleiades. Comparison with ROSAT HRI data taken 7
years previously reveals that only 10-15 percent of solar-type stars or stars
with Lx>3x10^{29} erg/s exhibit X-ray variability by more than a factor of two.
The similar levels of X-ray activity and rate of occurrence for large flares in
NGC 2547 and the ONC demonstrate that the X-ray radiation environment around
young solar-type stars remains relatively constant over their first 30 Myr
(abridged).Comment: Accepted for publication in MNRAS. Electronic tables available from
the autho
Enhanced electron correlations, local moments, and Curie temperature in strained MnAs nanocrystals embedded in GaAs
We have studied the electronic structure of hexagonal MnAs, as epitaxial
continuous film on GaAs(001) and as nanocrystals embedded in GaAs, by Mn 2p
core-level photoemission spectroscopy. Configuration-interaction analyses based
on a cluster model show that the ground state of the embedded MnAs nanocrystals
is dominated by a d5 configuration that maximizes the local Mn moment.
Nanoscaling and strain significantly alter the properties of MnAs. Internal
strain in the nanocrystals results in reduced p-d hybridization and enhanced
ionic character of the Mn-As bonding interactions. The spatial confinement and
reduced p-d hybridization in the nanocrystals lead to enhanced d-electron
localization, triggering d-d electron correlations and enhancing local Mn
moments. These changes in the electronic structure of MnAs have an advantageous
effect on the Curie temperature of the nanocrystals, which is measured to be
remarkably higher than that of bulk MnAs.Comment: 4 figures, 2 table
Heat Stress and Reproduction in Beef Cattle
Reproduction could be considered the most important production trait on a cow-calf operation. Economic outputs are sustained when cattle rebreed and calve every year in a timely manner. However, when cattle are unable to rebreed efficiently, profits may decrease for producers. It is well known that heat stress can negatively impact reproduction in cattle (Jordan, 2003). The Intermountain West has been impacted by drought and increasing temperatures, both of which can impact reproduction rates in cattle. This fact sheet helps producers understand the consequences of heat stress on cattle reproduction and how they can manage reproduction during increasing temperatures
X-rays from T Tau: A test case for accreting T Tauri stars
We test models for the generation of X-rays in accreting T Tauri stars (TTS),
using X-ray data from the classical TTS T Tau. High-resolution spectroscopy
from the Reflection Grating Spectrometers on XMM-Newton is used to infer
electron densities, element abundances and the thermal structure of the X-ray
source. We also discuss the ultraviolet light curve obtained by the Optical
Monitor, and complementary ground-based photometry. A high-resolution image
from Chandra constrains contributions from the two companions of T Tau N. The
X-ray grating spectrum is rich in emission lines, but shows an unusual mixture
of features from very hot (~30 MK) and very cool (1-3 MK) plasma, both emitted
by similar amounts of emission measure. The cool plasma confirms the picture of
a soft excess in the form of an enhanced OVII/OVIII Lya flux ratio, similar to
that previously reported for other accreting TTS. Diagnostics from lines formed
by this plasma indicate low electron densities (<~ 1E10 cm-3). The Ne/Fe
abundance ratio is consistent with a trend in pre-main sequence stars in which
this ratio depends on spectral type, but not on accretion. On the basis of line
density diagnostics, we conclude that the density of the cool ``soft-excess''
plasma is orders of magnitude below that predicted for an accretion shock,
assuming previously determined accretion rates of (3-6)E-8 M_sun/y. We argue
that loading of magnetic field lines with infalling material suppresses the
heating process in a part of the corona. We thus suggest that the X-ray
production of T Tau is influenced by the accretion process although the X-rays
may not form in the bulk of the accretion footpoints.Comment: 12 pages, 7 figures, A&A style. Accepted by A&A, to appear in a
special section/issue dedicated to the XMM-Newton Extended Survey of the
Taurus Molecular Cloud (XEST). See also
http://www.issibern.ch/teams/Taurus/papers.htm
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