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Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.
SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.
SPICA instruments offer spectral resolving power ranging from R ~50 through 11 000 in the 17–230 μm domain and R ~28.000 spectroscopy between 12 and 18 μm. SPICA will provide efficient 30–37 μm broad band mapping, and small field spectroscopic and polarimetric imaging at 100, 200 and 350 μm. SPICA will provide infrared spectroscopy with an unprecedented sensitivity of ~5 × 10−20 W m−2 (5σ/1 h)—over two orders of magnitude improvement over what earlier missions. This exceptional performance leap, will open entirely new domains in infrared astronomy; galaxy evolution and metal production over cosmic time, dust formation and evolution from very early epochs onwards, the formation history of planetary systems.
Using semi-empirical isochrones, we find the age of the Taurus star-forming region to be 3-4 Myr. Comparing the disc fraction in Taurus to young massive clusters suggests discs survive longer in this low density environment. We also present a method of photometrically de-reddening young stars using iZJH data.
The Magellanic System represents one of the best places to study the formation and evolution of galaxies. Photometric surveys of various depths, areas and wavelengths have had a significant impact on our understanding of the system; however, a complete picture is still lacking. VMC (the VISTA near-infrared YJKs survey of the Magellanic System) will provide new data to derive the spatially resolved star formation history and to construct a three-dimensional map of the system. These data combined with those from other ongoing and planned surveys will give us an absolutely unique view of the system opening up the doors to truly new science!
Suicides are prone to misclassification during death-ascertainment procedures. This problem has generated frequent criticism of the validity of suicide mortality statistics. The study aim was to employ an external measure of the validity of cause-of-death statistics, national autopsy rates, to examine potential misclassification of suicide across 35 countries. Data for the time period 1979–2007, were employed to analyze the association between suicide rates and autopsy rates and death rates of undetermined and ill-defined causes, respectively. Autopsy rates among nations were associated with suicide rates. These respective associations were robust with adjustment for unemployment, degree of urbanization, and the rate of undetermined or ill-defined deaths. Associations strengthened when analyses were confined to 19 EU member countries. Based on these results, we conclude that autopsy rates may impact the validity of suicide mortality statistics. Therefore, caution should be exercised in comparing international suicide rates and evaluating interventions that target suicide rate reduction.
Associations between animal behaviour and emissions of methane (CH4) and ammonia (NH3) have been noted in studies of grazing cattle (Lockyer, 1997) and feedlot confined cattle (Harper et al., 1999, Flesch et al., 2007). Methane emissions have been predicted as being greatest during bouts of rumination (Harper et al., 1999) whereas the emissions of the indirect greenhouse gas ammonia tends to be low early in the morning but increasing rapidly in the early afternoon after which a rapid decline until sunset (Flesch et al., 2007). With the exception of Harper et al., (1999) there are few complete data sets that examine the interaction between animal behaviour and greenhouse gas emissions from intensive animal production systems. The current study aimed to investigate the relationship between animal behaviour and emissions of CH4 and NH3 in a beef feedlot system in northern Australia.
Feedlot management systems for beef cattle are becoming a more common practice in Australia reflecting opportunities to ensure quality of product whilst maintaining cost efficiencies within production. However, feedlot systems have been identified as point sources of greenhouse gases emissions (GGE: methane, nitrous oxide and the indirect greenhouse gas ammonia). It has been estimated that feedlot systems contribute 3.5% of total direct methane emissions (Alford et al. 2006), and 30% of total emissions from livestock wastes. Furthermore, approximately 1% of total N2O emissions from agriculture are attributed to livestock. This paper reports methane, N2O and NH3 emissions from an Australian feedlot system managed under summer climatic conditions. It compares actual measured emissions with estimated from three recognised models used by national governments to estimate total GGE per annum from livestock agriculture.
The response of germination and early seedling growth to levels of salinity (0, 50, 100, 150, 200 and 250 mM NaCl) were examined in single seed lots of ten modern rice genotypes. Unaged and deteriorated rice seeds were germinated in rolled paper towels and in Petri dishes. Initial seed quality, final germination, germination rate and early seedling growth were assessed. The samples of the rice genotypes differed in their initial seed quality (measured in terms of Ki). The effect of deterioration varied depending upon the initial seed quality and the severity of the treatment imposed. Ageing (using the technique of controlled deterioration, CD) for up to 24 h had no effect on final germination levels. Although CD for 30 h only reduced final germination slightly, ageing for 36 or 48 h reduced it greatly. Controlled deterioration for 36 h or longer reduced the final length and the rate of extension of both the plumule and radicle. Combining information about germination in salt solution with that about seed quality enabled a distinction to be made between varieties which performed poorly because they were genetically salt-susceptible from those which germinated poorly due to poor seed quality. It is argued that the seed vigour of seed lots used in genotype evaluation should be assessed in order to avoid discarding potentially useful genotypes because of poor physiological seed quality.
The results of field experiments in 1983/84 and 1984/85
used to test the hypotheses (i) that
cultivars and management systems which result in high biomass of
winter barley will also produce
high grain yield and (ii) that greater uniformity of tiller and
ear size is associated with greater yield.
In a set of cultivars, grain yield per plant was significantly
correlated with biomass per plant despite
no correlation with any individual yield component. Biomass per
shoot was significantly correlated
with grain yield per shoot. Treatments to increase shoot uniformity
(the mass of individual tillers
relative to that of the main stem) generally increased biomass per
shoot and grain yield per shoot.
The re-examination of data in the literature where yield and biomass
were available confirmed the
association of biomass and grain yield both on a per plant and per
shoot basis. It is argued that
harvest index is not a character which can be easily targeted for
manipulation by growers, whereas
crop management systems to increase biomass should be easier to specify.
The nova-like variable BZ Cam (also called 0623+71) is an unusual cataclysmic variable star in that it resides in a nebula, discovered by Ellis, Grayson, & Bond (1984) and designated EGB 4. It is more unusual in that its optical spectrum reveals a wind from its accretion disk. This was discovered serendipitously during a radial velocity study to find orbital period by Thorstensen, Thomas, & Patterson (1993; see also Patterson et al. 1996), who found intermittent P Cygni profiles in the He I λ 5876 Å and Hα emission lines.
The 4.2-m William Herschel Telescope and its ISIS spectrograph were used to obtain time-resolved spectra of these lines with 0.4 Å/pixel dispersion and 30-second time resolution. These new spectra have about 5 times the spectral resolution and 24 times the time resolution of those of Thorstensen et al. (1993). These observations were obtained on the nights of 1995 February 6 – 8 UT. The blue arm of ISIS was centered on the He I λ 5876 Å; the red arm covered Hα. Typical signal-to-noise ratio was 18 per resolution element.
Classical nova outbursts are thermonuclear explosions on the surfaces of the white dwarfs in cataclysmic variables. The explosion heats the surface layers of the white dwarf, which are expected to cool on a timescale of a hundred years. The hot white dwarf should have two obvious effects on the system.
(1)It will heat the surface of the accretion disc and secondary star, increasing the overall luminosity of the system.
(2)By irradiating the surface of the secondary star it may bloat it and drive more mass transfer, thus again increasing the overall luminosity.
We present infrared (IR) photometry and optical spectroscopy of the eclipsing old nova WY Sge. According to hibernation theorists the disc in a system a few centuries after outburst should be significantly fainter than in other, more recent, old novae but similar to the discs of dwarf novae in quiescence. Despite the apparent faintness of the late type star we have sufficient information to infer that the face closest to the white dwarf (WD) is irradiated.
We report on a 1-day ASCA observation of the eclipsing dwarf nova HT Cas. We confirm the presence of an X-ray eclipse, which is narrow and deep. The data are consistent with the X-rays originating entirely from the immediate neighborhood of the white dwarf. We draw some preliminary conclusions on the boundary layer and other relevant issues.
IP Peg is a U Gem-type dwarf nova with a very high orbital inclination such that the secondary star eclipses the white dwarf primary, accretion disc and hot spot in each orbit. An observing project was set up by ‘The Astronomer’ (TA) magazine and the British Astronomical Association Variable Star Section to make visual and CCD eclipse observations of IP Peg during outbursts in the 1994/95 season.
This paper reports the observation of high-n lines in emission from n = 12-11, 13-12, 14-13 and 16-15 Rydberg transitions in H, Mg and Si in solar far IR spectra taken from balloon altitudes, in which the H I line intensities are found to exceed those from the heavier elements. Tentative identification is also made of the n = 8-7 hydrogen line in emission on 20 μm spectra taken from Mauna Kea. The characteristics of the hydrogen lines are compared with lower-n transitions seen in the Space Shuttle ATMOS spectra, in which Brackett, Pfund and n = 6 lines with Δn = 1, 2, 3 and 4 are seen as broad absorption features, while the n = 7-6 line shows a small emission peak within a broader absorption line and the n = 9-7, and possibly the 11-8, transitions appear as weak emission lines. These results indicate that the transformation from absorption to emission occurs at longer wavelengths for hydrogen lines than for those of heavier elements.
A two-beam Martin-Puplett polarizing interferometer has been used in the rapid-scan mode on the 15 meter JCMT in conjunction with the facility detector, UKT14, to survey the solar sub-millimeter and millimeter spectrum in the four wavebands at 7-11, 11-15, 21-24 and 27-30 cm–1 to a spectral resolution of 0.01 cm–1 and at spatial resolutions of 19″, 16″, 7″ and 6″, respectively. Overall atmospheric transmission through these windows has been evaluated by comparison with synthetic spectra generated with FASCOD/HITRAN. A search has been made for contributions to these spectra from high-n transitions of H and heavier elements by several methods, including the comparison of solar with lunar and limb with disk center spectra.
Near IR total eclipse measurements have provided clear evidence during both 2nd and 3rd contacts for a limb extension of about 125 km for wavelengths in the range containing the CO fundamental vibration-rotation bands between 4.3 and 5.5 μm, when compared to the limb at nearby shorter wavelengths. This is interpreted as a “flash” spectrum in the CO lines, with the above extension representing the outer level of the CO emission layer. This height can be compared to the τCO = 1.0 level incorporated into recent representative atmospheric models (Ayres and Wiedemann, 1989) which is 90 km above the visible limb for a semi-empirical “hot chromosphere” model (Avrett, 1985) and 220 km for a “cool” radiative equilibrium model based upon work by Anderson (1989).
We present ultraviolet and X-ray observations of the eclipsing SU UMa dwarf nova OY Car early in the decline from a superoutburst. From the UV emission line spectrum and lack of X-ray eclipse, we deduce the presence of an extended coronal region.
We present optical and IR observations of the dwarf nova OY Car during the May 1985 superoutburst. From them we find that the superhump has a temperature of ~8000K and an area of order half the size of the red dwarf or accretion disk. We also compare the behaviour during two simultaneous optical/IR observations. Whilst the light curves in the two pass bands are similar during one observation, in the other observation they show marked differences that may be due to a cool region in the outer disk.
Atmospheric gas samples (0.1m3) were collected at ground level during January/February 1984 in Las Vegas, Nevada for 14C/13C accelerator mass spectrometry and total abundance measurements of CO and CH4. During winter months in this locale, CO concentrations can occur at 10 to 100 times background, occasionally exceeding the National Ambient Air Quality Standard (NAAQS). Methane concentrations show a slight enhancement (∼24%) above the background (non-urban troposphere) level. A comparison of CO and CH4 concentrations shows a good linear correlation which may indicate a common source. Preliminary 14C/13C results of the two species suggest that fossil emissions are the predominant source of excess CO and CH4 in the samples taken. Estimates of anthropogenic CO and CH4 are important for source apportionment of combustion emissions. In addition, this information is valuable for understanding the global CO and CH4 cycles and, therefore, human impact on climate and the stratospheric ozone layer.