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In conservation biology, population monitoring is a critical step, particularly for endangered groups, such as steppe birds in European agro-ecosystems. Long-term population monitoring allows for determination of species population trends and also provides insights into the relative roles that environmental variability and human activities have on priority species. Here, we compare the population trends of two sympatric, closely related farmland bird species, the Little Bustard Tetrax tetrax and Great Bustard Otis tarda, in a protected area of Central Spain, which is their main stronghold in Europe. Over 12 years of monitoring, the abundance of Little and Great Bustards shifted in opposite directions in our study area. Little Bustard abundance decreased significantly (both males [-56%], and harder-to-detect females [-55%]), while Great Bustard abundance increased significantly (1,800%). Future surveys should be more precise and frequent for Little Bustards to facilitate evaluation of their population status and trends. We recommend annual surveys in 2–3 important locations by region throughout the breeding range for Little Bustards, while for Great Bustard the current regional monitoring programmes would be sufficient.
We summarize the discussion of the current status and future prospects of space and astrophysical plasma research prepared by the Panel on Space and Astrophysical plasmas, a part of the study on Physics administered by the National Research Council of the National Academy of Sciences. The Study on Physics is chaired by W. Brinkman of Bell Laboratories and will be completed in 1984.
A variety of studies over the last decade has shown molecular hydrogen to be a major constituent of the interstellar medium both in our Galaxy and in other spiral galaxies (Morris and Rickard, 1982). Our Galaxy contains roughly M(H2) = 4 × 109 M⊙; between R = 2 kpc and R = 10 kpc the H2 mass is one to three times that of HI; at the solar circle about 12 per cent of the total disk mass is in the form of H2; most of this mass is in the form of several thousand giant molecular cloud complexes (GMCs) with sizes d > 20 pc and masses M(H2) > 105 MO (Cohen et al, 1980; Sanders, 1981; Dame, 1983). These GMCs mainly consist of clumps with much smaller scales of order a few pc or less (e.g. Bally and Israel, 1983). Apart from their contribution to the total mass of the galactic interstellar medium, molecular clouds are also important as they are the major birthsite of massive early-type stars (see the review by Habing and Israel, 1979).
We have used the Estec/Utrecht heterodyne submillimetre receiver together with the 1.4 m ESO CAT at La Silla (Chile) to survey the southern Galaxy (1 = 270 − 355°) in the CO(2–1) transition at 230 GHz (1.3 mm). The beam used had a HPBW size of 5.5 arcmin, overall system efficiency was 0.35, and the system temperature was 1400 – 1750 K (DSB). Our filterbanks had velocity resolutions of 1.3 and 0.325 km s−1 and velocity ranges of 333 and 83 km s−1 respectively.
We have used the Estec/Utrecht heterodyne submillimetre receiver and the ESO 3.6-m telescope at La Silla (Chile) to observe the CO(2–1) transition at 230 GHz (1.3 mm) in the Magellanic Clouds. We used a beam of 2 arcmin HPBW (corresponding to linear resolutions of 32 and 46 pc for LMC and SMC respectively), the system temperature was 2200 K (DSB) and the overall system efficiency was 0.55. In this paper we summarize the results, which are published in more detail elsewhere (cf. Israel et al., 1982, 1983; Israel, 1984).
Spiral galaxies whose radio continuum emission is dominated by their disks show a flattening of the radio continuum spectrum at frequencies well below 1 GHz. The effect appears to be stronger for edge-on than for face-on galaxies The most feasible explanation appears to be that the flattening reflects free-free absorption of nonthermal emission by a very low temperature ionized gas. This gas is probably highly clumped, and must be well-mixed with the nonthermally emitting plasma.
The 1.2 m telescope at the Center for Astrophysics is being used to carry out the first complete CO survey of M31. To date, the entire galaxy out to a radius of at least 15 kpc —- well beyond the optical disk and H I ring — has been observed every half-beamwidth (4.5'), with ∼1 hr of integration per point yielding an rms of 20 mK in 1.3 km s—1 channels. Like H I and other Population I tracers, molecular clouds in M31 are mainly concentrated in a broad ring with a radius of ∼10 kpc, but beyond the peak of the ring molecular gas falls off more sharply than atomic gas. On the assumption of a standard Galactic value for the conversion of CO emission to H2 mass, the average molecular surface density at the peak of the ring is ∼1 M⊙ pc-2 and the total molecular mass of M31 is ∼3 × 108 M⊙. The survey will be essentially repeated during the coming year to improve the signal-to-noise.
Molecular gas is a major constituent of the interstellar medium of all late-type galaxies. Virtually all of it is in the form of cold molecular hydrogen (H2) which today cannot be observed directly. However, the tracer molecule carbon monoxide (CO) (relative abundance 10−5) is easily detected. For the Magellanic Clouds (MCs), CO studies are of specific importance. The Clouds are rich in HI, and if we can establish the presence of significant amounts of H2 as well, this will influence our estimates of the global rate of star formation and its history. Complexes of presently quiescent molecular gas may betray regions primed for star formation, but not yet in action. Detailed studies of the HI, HII and H2 and young star content may provide estimates of star formation efficiences on scales of a kiloparsec.
With the detection of strong PAH features and H2 emission in selected knots of the N159, N11A, and 30 Dor regions in the LMC, we present the first results of a study that is part of a coordinated Guaranteed Time ISO programme to investigate star formation in the Magellanic Clouds. The PAH features have different ratios than the ones in Galactic reflection nebulae.
This report coveres the period 1 July 1993 to 30 June 1996. In contrast to reports from previous triennia, which were written by commission officers, committee members, and chairs of working groups, all members of the comission were invited, through a newsletter, to volunteer to write sections on topics that interested them. About a dozen people volunteered, not all of whom were able to complete the reports they had suggested.
Over the last year we obtained X-ray (ROSAT, BeppoSAX and ASCA) and optical (at ESO and at the Astronomical Observatory of Loiano) to infra-red (AAO) observations of a sample of newly discovered X-ray pulsars. Among this sample we discovered the likely optical counterpart of three of them located in the Galactic plane: GS 0834–43, 1WGA J1958.2+3232 and AX J1820.5–1434.
We used the ESO 3.6 m telescope at La Silla (Chile) in conjunction with the Estec heterodyne receiver to observe CO (J=2-1) emission from southern sources. The telescope HPBW was 2.2 arcmin, the beam efficiency 43 per cent. The receiver used backward-wave oscillators and Schottky barrier diode mixers. It had a single-sideband noise temperature of 4000 K at 230 GHz. The backend was a 256 channel filterbank of 1 MHz (1.3 km s−1) bandwidth per channel. Calibration was done in the usual way.
We used the new OVRO 10 meter millimeter telescope together with the Estec heterodyne receiver and backend to observe 12CO (J=2-1) emission in the direction of several galactic HII regions. At a frequency of 230 GHz our angular resolution was 30 arcsec and our velocity resolutions were 0.3 and 1.3 km s-1. We observed the cores of 16 molecular clouds associated mainly with compact and subcompact HII regions: S88, S106, S157, S158 (NGC 7538), S159, S187, S228, S255 (IC 2162), S269, ON-1, G45.5-0.1, Wl (center), W58 (K3-50), Cep A and Mon R2. Observations of all sources were in a cross pattern of at least five points. Four sources - Cep A, Mon R2, S158 and W58 - were mapped in more detail. Results for the latter two are shown in Figures 1 and 2.
The Westerbork Synthesis Radio Telescope was used to map the continuum radiation of M33 at 1415 MHz. Of 67 radio sources with fluxes S> 1.8 mJy (3σ), 60% coincide with Hα sources. These are all intrinsically stronger than 4 × the Orion nebula, i.e., they are giant Hiiregions. The two strongest sources, NGC 604 (58 mJy) and NGC 595 (20 mJy), are similar to W51.
Supernovae play an integral role in the feedback of processed material back into the interstellar medium (ISM) of galaxies and are responsible for most of the chemical enrichment of the universe. The rate of supernovae can also reveal the star formation histories. In a sample of 11 nearby galaxies observed with SINFONI, a strong linear correlation between [FeII]1.26 luminosity and Starburst 99-derived supernova rate is found on a pixel-pixel basis. In the very nearby archetypal starburst galaxy NGC 253, the excitation of molecular gas is a subject of debate. Using the correlation between [FeII] and supernova rate, we can determine if supernovae can account for the excitation of the bright observed near-infrared H2 emission.
We present new imaging and spectral analysis of the recently discovered extended X–ray emission around the high-magnetic-field rotating radio transient RRAT J1819–1458. We used two Chandra observations, taken on 2008 May 31 and 2011 May 28. The diffuse X–ray emission was detected with a significance of ~19σ in the image obtained by combining the two observations. Long-term spectral variability has not been observed. Possible scenarios for the origin of this diffuse X–ray emission, further detailed in Camero–Arranz et al. (2012), are here discussed.
Frederick Carder popularized art glass in America and is remembered as the founder of Steuben Glass. He was a designer and glass technologist whose factory produced colored and highly decorated glass vessels that competed with but were less expensive than those of Tiffany Studios. To understand the differences in technology between the competing products of Carder and Tiffany, opalescent white glass formulations, fumed gold lusters and silver-containing glasses used in trailed decoration were analyzed and compared by electron beam microprobe analysis and scanning-electron microscopy with simultaneous energy dispersive x-ray analysis. Analytical results show standardized processing that includes opalescent compositions in a narrow range of soda-lime-silicate and lead-alkali-silicate glasses, fumed “golden” lusters made from tin and silver, and iridized surface layers formed by multiple heat treatments.