368 research outputs found
A Multicoloured View of 2S 0114+650
We report the results of radio and X-ray observations of the high mass X-ray
binary 2S 0114+650, made with the Giant Meterwave Radio Telescope and the Rossi
X-ray Timing Explorer respectively. No emission was detected at radio
wavelengths. The neutral hydrogen column density was found to vary over the
orbital period, while no variability over the the super-orbital period was
observed. We discuss the causes of the observed relationships and the
implications for the underlying mechanisms.Comment: 4 pages, 2 figures; to appear in proceedings for "The multicoloured
landscape of compact objects and their explosive progenitors", Cefalu,
Sicily, 2006 June 11-24, AIP, submitte
Ανάδειξη της αγροτικής παραγωγής στην αστική καθημερινότητα. _προβολή _ εμπόριο _ ενημέρωση στην Θήβα
An 'aggregate economic' value (H), which is a combination of genetic control and relative economic value of traits, for all traits in the breeding objective was developed to aid in multitrait selection of strawberry cultivars in the subtropical southeast Queensland program. A profitability index for 12 traits was calculated from the effect of unit changes in each trait on changes in production costs and profitability. The index was applied to the breeding values of 3008 genotypes to produce estimates of H. H was validated by its high correlation (R=0.77) with year of selection (1945-1998) for commercial cultivars. H values for 3008 genotypes ranged from -0.36 to +0.28, when the zero value was set to the value of the cultivar 'Festival', which is the main cultivar grown in southeast Queensland. Modelling indicated that the gross margins were highly linearly related (R0.98) to H values where the genotype occupied less than 50% of total area planted in the industry, but this relationship became quadratic when the genotype occupied higher percentages of the total area planted to strawberries, and variation in gross margin increased as H values increased. H is efficient in identifying economically superior genotypes, but, when deploying new genotypes with high H, impacts on farm gross margin due to high adoption rates should also be considered
Internode length of hoop pine: genetic parameters and prospects for developing a long internode breed
Selection of Corymbia citriodora for pulp productivity
Evaluation of a series of spotted gum (Corymbia citirodora) progeny trials, established in the subtropical region of Queensland, Australia, was undertaken to provide information for the development of advanced-generation breeding populations suitable for pulp production. Measurements of growth at two ages were combined with assessments of wood density and pulp yield from a selected sample of provenances to provide comparisons between provenances, to generate genetic parameter estimates and to predict genetic gain potential. Although growth at this age was moderate relative to other eucalypts, the near-infrared predictions of average wood density of 756 kg m-3 and pulp yield of 55% indicate the species has considerable potential as a pulpwood crop. A pulp productivity breeding objective was used to identify production populations using a range of selection trait weightings to determine potential genetic gain for pulp productivity. Genetic parameters indicated (1) levels of genetic control were moderate for all traits and higher for wood property traits, (2) genetic improvements could be achieved by selection among and within provenances with greater levels of improvement available from selection within populations, (3) genotype by environment interactions were negligible, (4) genetic correlations between traits were favourable, and (5) selection of volume production alone would maximise improvements in pulp productivity
Timing Noise in SGR 1806-20
We have phase connected a sequence of RXTE PCA observations of SGR 1806-20
covering 178 days. We find a simple secular spin-down model does not adequately
fit the data. The period derivative varies gradually during the observations
between 8.1 and 11.7 * 10^-11 s/s (at its highest, ~40% larger than the long
term trend), while the average burst rate as seen with BATSE drops throughout
the time interval. The phase residuals give no compelling evidence for
periodicity, but more closely resemble timing noise as seen in radio pulsars.
The magnitude of the timing noise, however, is large relative to the noise
level typically found in radio pulsars. Combining these results with the noise
levels measured for some AXPs, we find all magnetar candidates have \Delta_8
values larger than those expected from a simple extrapolation of the
correlation found in radio pulsars. We find that the timing noise in SGR
1806-20 is greater than or equal to the levels found in some accreting systems
(e.g., Vela X-1, 4U 1538-52 and 4U 1626-67), but the spin-down of SGR 1806-20
has thus far maintained coherence over 6 years. Alternatively, an orbital model
with a period P_orb = 733 days provides a statistically acceptable fit to the
data. If the phase residuals are created by Doppler shifts from a
gravitationally bound companion, then the allowed parameter space for the mass
function (small) and orbital separation (large) rule out the possibility of
accretion from the companion sufficient to power the persistent emission from
the SGR.Comment: 11 pages, accepted for publication in ApJ Letter
Discovery of a New Soft Gamma Repeater, SGR 1627-41
We report the discovery of a new soft gamma repeater (SGR), SGR 1627-41, and
present BATSE observations of the burst emission and BeppoSAX NFI observations
of the probable persistent X-ray counterpart to this SGR. All but one burst
spectrum are well fit by an optically thin thermal bremsstrahlung (OTTB) model
with kT values between 25 and 35 keV. The spectrum of the X-ray counterpart,
SAX J1635.8-4736, is similar to that of other persistent SGR X-ray
counterparts. We find weak evidence for a periodic signal at 6.41 s in the
light curve for this source. Like other SGRs, this source appears to be
associated with a young supernova remnant G337.0-0.1. Based upon the peak
luminosities of bursts observed from this SGR, we find a lower limit on the
dipole magnetic field of the neutron star B_dipole > 5 * 10^14 Gauss.Comment: 5 pages, 4 figures, submitted to ApJ Letter
Sub-tropical exotic pine taxa, growth, form and wood properties comparisons across multiple sites in coastal Queensland in: thinning and clearfall age trials; in family and clonal hybrid pine trials and in a genetics x fertiliser x weed control trial.
This project supports improved management and deployment of sub-tropical pines for solid
wood products. It had three major objectives, in respect of both growth rate and standing tree wood properties: 1) to compare major and potential pine species and hybrids for south-east Queensland; 2) to investigate selection strategies for identifying improved families and clones, and make selections; and, 3) to evaluate both the separate and combined effects of fertiliser application, weed control and genetic improvement in a young hybrid pine trial
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