bluuebunny/crossref_metadata_2025 huggingface dataset:
The Warm Ionised Medium in Spiral Galaxies: A View from Above
Authors: Walterbos René A. M.
Published: March 2011

The warm ionised medium (WIM), also referred to as diffuse ionised gas (DIG), contains most of the mass of interstellar medium in ionised form, contributing as much as 30% of the total atomic gas mass in the solar neighborhood. The advent of CCDs has enabled unprecedented study of this medium in external galaxies, probing a variety of environments. In particular, we can derive the morphology of the WIM, its distribution across disks, and the correlation with other Population I material. Spectroscopy of the WIM makes it possible to test various ionisation models. I will review here our current understanding of the properties of the WIM in spiral galaxies. A perhaps unexpected result is that the Hα emission from the WIM contributes about 40% of the total observed Hα luminosity from spirals. This places severe constraints on possible sources of ionisation, since only photoionisation by OB stars meets this requirement. Spectroscopic measurements of forbidden line strengths appear in reasonable agreement with photoionisation models. It is not yet clear if the Lyman continuum photons that ionise the WIM are mostly from OB stars located inside traditional HII regions, or from field OB stars.
Diffuse Ionised Gas in Edge-on Galaxies
Authors: Rand Richard J.
Published: March 2011

We review observations of diffuse ionised gas (DIG) in edge-on spiral galaxies. Deep imaging has revealed a variety of morphologies for ‘extraplanar’ (above the HII region layer) or ‘halo’ DIG: some show widespread prominent layers of truly diffuse gas and filamentary structures, others show just one patch or a few patches of extraplanar emission, while still others show no detectable extraplanar DIG at all. The key galactic property which appears to govern the prominence of the DIG layer is the star-formation activity. Smaller-scale connections between DIG and local star formation activity can be seen in some of the galaxies.

DIG halos are also related to radio continuum, X-ray and HI halos. Those galaxies with the most prominent DIG layers also have the most prominent radio halos. In NGC 891, there are spatial correlations between extraplanar DIG, radio emission, X-ray emission and HI, and these in turn are related to the underlying disk star-formation activity.

Progress on identifying the sources of ionisation and heating of the gas has come from spectroscopy, imaging in different emission lines, and Fabry–Perot observations. By comparing with theoretical predictions, much evidence is found for photoionisation by disk stars as the primary ionisation and heating mechanism, but recent observations are beginning to point towards the need for additional sources of ionisation and/or heating.
Cosmological Applications of Hα Surveys
Authors: Valls–Gabaud David
Published: March 2011

We briefly review three main applications of Hα surveys in cosmology, namely: (1) the diffuse Hα emission as a tracer of the free–free foreground that contaminates the fluctuations in the cosmic microwave background radiation; (2) the Hα emission from galaxies as a measure of the formation rate of massive stars, both at low and high redshift; and (3) the diffuse Hα emission from ionised clouds as a constraint on the local ionising background radiation.
Neutral and Ionised Hydrogen in NGC 4214
Authors: McIntyre V. J.
Published: March 2011

It is not clear at present how the diffuse ionised gas (DIG) component in galaxies is ionised. The leading hypothesis is that ultraviolet photons from star clusters are responsible, but this requires a rather porous interstellar medium if the photons are to travel the large distances (≥ 1 kpc) between the bright clusters and diffuse-emission regions. To examine this hypothesis, we present high-resolution VLA observations of the neutral hydrogen in the Magellanic galaxy NGC 4214, and compare them with an Hα image. The data appear consistent with the idea that enough UV photons escape from supergiant H II regions to ionise the DIG.
Quantifying the Ionising Flux escaping from the Ultra-luminous H II Regions in Four Spiral Galaxies
Authors: Rozas M. , Zurita A. , Beckman J. E.
Published: March 2011

There are two principal problems in explaining, in terms of the emission from OB stars, the ionisation of gas which emits diffuse Hα in spiral galaxies. One is the long pathlength which the ionising photons need to traverse to reach their objectives, the other is whether sufficient photons can escape from within the H II regions which surround the hot stars. Here we treat the second point, assuming that the H II regions above a certain threshold luminosity are density bounded. We calculate the escaping Lyman continuum (Lyc) fluxes from the density bounded regions in four galaxies, and show that in each of them this is easily suffcient to produce the measured diffuse Hα emission.
Image Digitisation of Outflows and the AAO/UKST Hα Survey
Authors: Zealey W. J. , Mader S. L.
Published: March 2011

The Hα emission-line survey of the Southern Sky to be carried out by the AAO/UKST will provide deep, high resolution images of Galactic Plane sources allowing the detection of new and existing filamentary sources such as Herbig–Haro objects. Used in conjunction with the existing ESO/SERC Southern Sky Survey Plates, the Hα plates will provide us with the opportunity to study the morphology and environment of new and existing star forming regions.
Hipparcos Observations of Hydrogen-deficient Carbon Stars
Authors: Cottrell P. L. , Lawson W. A.
Published: March 2011

Parallax measurements for 21 hydrogen-deficient carbon stars have been made by the Hipparcos satellite. These stars include most of the brighter R Coronae Borealis (RCB) variables, other cool hydrogen-deficient carbon (HdC) stars, and several higher-Teff extreme helium (eHe) stars. Most of these stars have either negative or statistically insignificant parallaxes, indicating that they lie beyond the detection capability of Hipparcos. Although the distances to the galactic hydrogen-deficient carbon stars remain unknown, at least the Hipparcos observations do confirm that these objects must have high luminosity like the LMC RCB stars, for which Mbol = −4 to −5. Based upon Hipparcos proper motions, we derive UVW velocities for the RCB and HdC stars, assuming Mbol = −3 and −5. The UW -velocity dispersion of the RCB/HdC stars is similar to that already reported for the eHe stars, further supporting the idea that these groups of stars have predominantly bulge distributions. However, UW Cen may be a second example of a halo RCB star currently seen transitting the Galactic plane.
Near-IR Fluorescent Molecular Hydrogen Emission from NGC 2023
Authors: Burton Michael G. , Howe J. E. , Geballe T. R. , Brand P. W. J. L.
Published: March 2011

Spectra from 1 to 2·5 μm, at 230–430 spectral resolution, are presented of the fluorescent molecular hydrogen line emission from two locations in the reflection nebula NGC 2023. Over 100 H2 lines can be identified in the spectra, although blending and poor atmospheric transmission mean that reliable level column densities can only be obtained from 35 lines. This latter group includes lines from v = 1–8 and v = 10, spanning an energy range from 6000 to 45,000 K above the ground state. These data may be used to constrain models of photodissociation regions and of fluorescent excitation for molecular hydrogen.
UNSWIRF: A Tunable Imaging Spectrometer for the Near-Infrared
Authors: Ryder Stuart D. , Sun Yin-Sheng , Ashley Michael C. B. , Burton Michael G. , Allen Lori E. , Storey John W. V.
Published: March 2011

We describe the specifications, characteristics, calibration, and analysis of data from the University of New South Wales Infrared Fabry–Perot (UNSWIRF) etalon. UNSWIRF is a near-infrared tunable imaging spectrometer, used primarily in conjunction with IRIS on the AAT, but suitable for use as a visitor instrument at other telescopes. The etalon delivers a resolving power in excess of 4000 (corresponding to a velocity resolution ∼75 km s−1), and allows imaging of fields up to 100″ in diameter on the AAT at any wavelength between 1·5 and 2·4 μm for which suitable blocking filters are available.
Torque Reversals in Disk Accreting Pulsars
Authors: Li Jianke , Wickramasinghe Dayal T.
Published: March 2011

X-ray binaries in which the accreting component is a neutron star commonly exhibit significant changes in their spin. In the system Cen X-3, a disk accreting binary system, the pulsar was observed to spin up at a rate ḟ = 8 × 10−13 Hz s−1 when averaged over the past twenty years, but significant fluctuations were observed above this mean. Recent BASTE observations have disclosed that these fluctuations are much larger than previously noted, and appeared to be a system characteristic. The change in the spin state from spin-up to spin-down or vice-versa occurs on a time scale that is much shorter than the instrument can resolve (≤1 d), but appears always to be a similar amplitude, and to occur stochastically. These observations have posed a problem for the conventional torque–mass accretion relation for accreting pulsars, because in this model the spin rate is closely related to the accretion rate, and the latter needs to be finely tuned and to change abruptly to explain the observations. Here we review recent work in this direction and present a coherent picture that explains these observations. We also draw attention to some outstanding problems for future studies.
The Las Campanas/AAT Rich Cluster Survey
Authors: O'Hely Eileen , Couch Warrick J. , Smail Ian , Edge Alastair C. , Zabludoff Ann
Published: March 2011

Some unsolved cosmological questions remain in relation to the formation of structure in the universe. One way of addressing such questions is to use rich galaxy clusters as tracers of the growth of large-scale structure. To date, studies of rich clusters of galaxies have concentrated on systems generally at either high redshift or in the local universe. The properties of clusters and their constituent galaxies at these extrema are becoming well understood. In particular, it is becoming clear that rich clusters have undergone considerable evolution both dynamically and in their galaxy populations over the last 5–8 Gyr. We are undertaking a detailed study of rich clusters of galaxies in the range 0·05 ≲ z ≲ 0·15. Our results will be directly comparable to those of previous studies both at high and low redshift and, for the first time, provide continuous coverage across this important and unexplored transitory epoch in terms of galaxy evolution and structure growth.
A Radio Survey of the SMC at 843 MHz with the MOST: I. The Survey
Authors: Turtle A. J. , Ye Taisheng , Amy S.W. , Nicholls Jennifer
Published: March 2011

A radio survey at a frequency of 843 MHz of 36 square degrees containing the Small Magellanic Cloud (SMC) has been made with the Molonglo Observatory Synthesis Telescope (MOST). The angular resolution is around 45 arcsec and the rms noise is about 1 mJy per beam. The radio image of the region is presented showing over a thousand sources with a variety of angular sizes from unresolved to 10 arcmin. Most of the sources are presumed to be background objects but about 70 of the more extended sources are H II regions or supernova remnants within the SMC.
A Statistical Comparison of Line Strength Variations in Coma and Cluster Galaxies at z ~ 0·3
Authors: Jones Lewis A. , Couch Warrick J.
Published: March 2011

We present a statistical comparison between spectral line strength variations in Coma galaxies and galaxies in three rich clusters at z ~ 0.3. Using a principal component analysis, we have transformed the observable quantities, the line strengths, into new mutually orthogonal axes and found two specific results. First, more independent parameters are required to account for the line strength variations in the distant cluster data than in the Coma data, and second, line strengths which are not correlated in the distant cluster data are strongly coupled in the Coma data. These results suggest that galaxies in clusters have been homogenised such that most of the information from the conditions present at their formation has been destroyed. Hence, it may be possible that the present-day homogeneity of early-type galaxy properties, e.g. the fundamental plane relation, does not require a single formation scenario, but that a variety of formation scenarios for different galaxies could still yield the observed behaviour of nearby galaxies.
Observational Tests of a Double Loop Model for Solar Flares
Authors: Hardy S. J. , Melrose D. B. , Hudson H. S.
Published: March 2011

A model for the energetics of solar flares, developed by Melrose (1997), is based on magnetic reconnection between two current-carrying magnetic loops. A detailed numerical investigation of the model has been made to identify those configurations that lead to energy release in a flare. Our results predict a strong relation between the ratio of currents in the interacting loops for a favoured flare configuration, and provide further support for a proposed method of generating long loops connecting different active regions. Both of these predictions are amenable to observational verification.
Line Broadening Cross Sections for the Broadening of Transitions of Neutral Atoms by Collisions with Neutral Hydrogen
Authors: Barklem P. S. , Anstee S. D. , O'Mara B. J.
Published: March 2011

Line broadening cross sections for the broadening of spectral lines by collisions with neutral hydrogen atoms have been tabulated by Anstee & O'Mara (1995), Barklem & O'Mara (1997) and Barklem, O'Mara & Ross (1998) for s–p, p–s, p–d, d–p, d–f and f–d transitions. To make these data more accessible to the end user, fortran code which interpolates in these tabulations has been prepared and placed on the World Wide Web. It should be easy to incorporate this code into existing spectrum synthesis programs or to use it in a stand-alone mode to compute line broadening cross sections for specific transitions. The use of the code is demonstrated by its application to two transitions of astrophysical interest.
Gas and Galaxy Formation
Authors: Nulsen P. E. J.
Published: March 2011

The theory of galaxy formation is reviewed briefly. From the evidence of clusters today, the primordial gas fraction was 20% or more. Thus, while the Universe is dominated by dark matter, gas plays an appreciable role in galaxy formation. Collapses of dwarf protogalaxies produce predominantly cold gas. It is argued that, in such cold collapses, the collapsed gas is largely self-gravitating. As a result, gas processes play a critical role in determining the visible structure of galaxies.
HI Mass Function from HIPASS
Authors: Kilborn V. , Webster R. L. , Staveley-Smith L.
Published: March 2011

The HI Parkes All Sky Survey (HIPASS) is a blind search for extragalactic neutral hydrogen, covering the whole of the southern sky. We present the latest HI mass function (HIMF) constructed from a sample of 263 galaxies with declinations <−62°. Standard Σ1/Vmax and maximum likelihood techniques are used in the analysis. No upturn in the low-mass end of the HIMF is yet seen, though our selection procedure presently conspires against the lowest-mass galaxies.
Finding the Bivariate Brightness Distribution of Galaxies from an HI Selected Sample
Authors: Minchin R. F.
Published: March 2011

A method is presented that will enable the bivariate luminosity/surface brightness distribution of galaxies to be determined from a relatively small HI selected sample. This will be taken from the HI Parkes All Sky Survey (HIPASS). The advantages of using an HI sample in order to avoid the selection effects that are present at optical wavelengths are discussed. We are developing an algorithm to automatically extract a uniform sample of galaxies from the HIPASS data cubes and to determine the parameters of these galaxies. We have so far conducted tests involving both simulated sources injected into cubes with real noise and data from the Multibeam Deep survey. Results from these tests are encouraging.
HI Observations of Southern LSB Dwarf Galaxies from the Karachentsev Catalogue
Authors: Huchtmeier Walter K. , Ehle Matthias
Published: March 2011

In this paper, we report on HI observations of newly detected nearby dwarf galaxies from the first part of the Karachentsev catalogue which contains low surface brightness galaxies spotted on the POSS II. We performed HI observations of 220 galaxies using the 100-m radio telescope at Effelsberg, the Nançay radio telescope, and the Australia Telescope Compact Array. We discuss global parameters of the whole sample and the observations of the southern sample in more detail. Global parameters of the observed galaxies are as expected from the sample of nearby galaxies (Kraan-Korteweg & Tammann 1979). The increase of the number of known galaxies in the Local Volume (i.e. within a distance of 10 Mpc) could be as high as 20% for the whole sky.
The HI Parkes Zone of Avoidance Shallow Survey
Authors: Henning P. A. , Staveley-Smith L. , Kraan-Korteweg R. C. , Sadler E. M.
Published: March 2011

The HI Parkes Zone of Avoidance Survey is a 21 cm blind search with the multibeam receiver on the 64-m radiotelescope, looking for galaxies hidden behind the southern Milky Way. The first, shallow (15 mJy rms) phase of the survey has uncovered 107 galaxies, two-thirds of which were previously unknown. The addition of these galaxies to existing extragalactic catalogues allows the connectivity of a very long, thin filament across the Zone of Avoidance within 3500 km s−1 to become evident. No local, hidden, very massive objects were uncovered. With similar results in the north (the Dwingeloo Obscured Galaxies Survey) our census of the most dynamically important HI-rich nearby galaxies is now complete, at least for those objects whose HI profiles are not totally buried in the Galactic HI signal. Tests are being devised to better quantify this remaining ZOA for blind HI searches. The full survey is ongoing, and is expected to produce a catalogue of thousands of objects when it is finished.
Blind HI Survey in the Great Attractor Region
Authors: Juraszek S.
Published: March 2011

Optically, the Zone of Avoidance (ZOA) can only be explored to within a few degrees of the Galactic Equator. This restriction does not apply to radio wavelengths where we are able to detect galaxies at great distances behind the Galactic Plane. Using the Parkes 21 cm multibeam instrument we have detected neutral hydrogen (HI) in 42 galaxies in the region of the Great Attractor. We have been able to identify nine galaxies and make positional associations with a further six from existing optical catalogues, which makes at least 60% of these galaxies new discoveries.
DENIS Observations of Multibeam Galaxies in the Zone of Avoidance
Authors: Schröder A. , Kraan-Korteweg R. C. , Mamon G. A.
Published: March 2011

Roughly 25% of the optical extragalactic sky is obscured by the dust and stars of our Milky Way. Dynamically important structures might still lie hidden in this zone. Various surveys are presently being employed to uncover the galaxy distribution in the Zone of Avoidance (ZOA), but all suffer from (different) limitations and selection effects. We illustrate the promise of using a multi-wavelength approach for extragalactic large-scale studies behind the ZOA, i.e. a combination of three surveys, optical, systematic blind HI and near-infrared (NIR), which will allow the mapping of the peculiar velocity field in the ZOA through the NIR Tully–Fisher relation. In particular, we present here the results of cross-identifying HI-detected galaxies with the DENIS NIR survey, and the use of NIR colours to determine foreground extinctions.
Deep Observations with the Parkes 21-cm Multibeam System
Authors: Disney M. J. , Boyce P. J. , Banks G. D. , Minchin R. F. , Wright A. E.
Published: March 2011

We report on a preliminary analysis of a 5600 sec per point survey of 32 square degrees in Centaurus, carried out with the Parkes 13-beam system. The signal-to-noise ratio is found to improve as for the whole integration. We have detected 102 HI sources between +250 and +12,700 km s−1 either by eye or by using the new galaxy-finding algorithm PICASSO. Over half of these are new HI detections. Around a dozen of these are not associated with catalogued galaxies and, in two of these cases, we have not identified an optical counterpart on the Digitized Sky Survey. Arguments are put forward to explain why deep integrations are needed to find low surface brightness objects.
A New HI Ring: LGG 138
Authors: Barnes David G.
Published: March 2011

A complete ring of neutral hydrogen gas (HI) in the LGG 138 group of galaxies has been found. The HI mass of the ring is greater than 109, and the gas appears to be rotating with a projected circular speed of ∼200 km s−1. Two bright galaxies are enclosed by the ring, both having radial velocities consistent with membership of the group. Faint stellar emission extends to the radial distance of the HI ring, where a small but distinct colour discontinuity of between 0·05 and 0·20 magnitudes is detected. Three simple models for the formation of the system are briefly described, the most likely appearing to be a past gas-sweeping collision between one of the two bright galaxies and an outside intruder, with the colour break being partly due to an expanding density wave that is triggering star formation, and partly to a different stellar population that has been collected from the outskirts of the intruder.
Constraints on Cold HI in the Halo of NGC 3079 from Absorption Measurements of Q0957+561
Authors: Irwin Judith A. , Widrow Lawrence M. , English Jayanne
Published: March 2011

We perform the first observational test of dark matter in the form of cold (3 K) fractal clouds, as described by Pfenniger et al. (1994) and Pfenniger & Combes (1994). This is accomplished by probing for HI absorption in the halo of NGC 3079 against the background quasar, Q 0957+561, which is separated from the centre of NGC 3079 by 64 kpc, in projection. No absorption is detected to a limit of 3ΔTb/(–Tc) = 0·01. We have considered models for HI + H2 clouds characterised by the cloud radius and fractal dimension. Using the upper limit on absorption, we have ruled out a limited but interesting region of this parameter space. The observations do not rule out the possibility that all the dark matter could be hidden in the form of cold fractal clouds. By contrast, if the gas is diffuse with unity filling factors, then HI cannot constitute more than ∼ 10−5, by mass, of the galaxy's dark matter.
New Structure in the Shapley Supercluster
Authors: Drinkwater M. J. , Proust D. , Parker Q. A. , Quintana H. , Slezak E.
Published: March 2011

We present new radial velocities for 306 bright (R < 16) galaxies in a 77 deg2 region of the Shapley supercluster, measured with the FLAIR-II spectrograph on the UK Schmidt Telescope. The galaxies we measured were uniformly distributed over the survey area, in contrast to previous samples which were concentrated in several rich Abell clusters. Most of the galaxies (230) were members of the Shapley supercluster: they trace out two previously unknown sheets of galaxies linking the Abell clusters of the supercluster. In a 44 deg2 area of the supercluster excluding the Abell clusters, these sheets alone represent an overdensity of a factor of 2·0 ± 0·2 compared to a uniform galaxy distribution. The supercluster is not flattened in the Declination direction as has been suggested in previous papers. Within our survey area the new galaxies contribute an additional 50% to the known contents of the Shapley supercluster, with a corresponding increase in its contribution to the motion of the Local Group.
Analytic Approximation to the Bounce-average Drift Angle for Gyrosynchrotron-emitting Electrons in the Magnetosphere of V471 Tauri
Authors: Nicholls Jennifer , Storey Michelle C.
Published: March 2011

Numerical modelling (Nicholls & Storey 1999) suggests that the eclipse of a wedge of enhanced number density of mildly relativistic electrons is responsible for the variations in quiescent radio emission of the binary system V471 Tauri. In the model, the wedge of enhanced density is created by electrons accelerated in the interaction region of the magnetospheres of the two stars, which subsequently drift in azimuth while emitting gyrosynchrotron emission. We present here an analytic approximation to the opening angle of the wedge of enhanced density and show that it is consistent with the opening angle derived from numerical modelling for reasonable values of the input parameters.
Millimetre Astronomy from the High Antarctic Plateau: Site Testing at Dome C
Authors: Valenziano L. , Dall'Oglio G.
Published: March 2011

Preliminary site testing results at Dome C (Antarctica) are presented, using both Automatic Weather Station (AWS) meteorological data (1986–1993) and Precipitable Water Vapour (PWV) measurements made by the authors. A comparison with the South Pole and other sites is made. The South Pole is a well established astrophysical observing site, where extremely good conditions are reported for a large fraction of time during the year. Dome C, where Italy and France are building a new scientific station, is a potential observing site in the millimetre and submillimetre range. AWS are operating at both sites and they have been continuously monitoring temperature, pressure and wind speed and direction for more than ten years. Site testing instruments are already operating at the South Pole (AASTO, Automated Astrophysical Site-Testing Observatory), while light experiments have been running at Dome C (APACHE, Antarctic Plateau Anisotropy CHasing Experiment) during summertime. A direct comparison between the two sites is planned in the near future, using the AASTO. The present analysis shows that the average wind speed is lower at Dome C (∼1 ms−1) than at the South Pole (∼2 ms−1), while temperature and PWV are comparable.
Angular Momentum Transfer in the Binary X-ray Pulsar GX 1+4
Authors: Greenhill J. G. , Galloway D. K. , Murray J. R.
Published: March 2011

Optical and X-ray spectroscopy indicate that the X-ray pulsar GX 1+4 is seen through a cloud of gravitationally bound matter. We discuss an unstable negative feedback mechanism (originally proposed by Kotani et al. 1999), based on X-ray heating of this matter which controls the accretion rate when the source is in a low X-ray luminosity state. A deep minimum lasting ∼6 hours occurred during observations with the RXTE satellite over 1996 July 19–21. The shape of the X-ray pulses changed remarkably from before to after the minimum. These changes may be related to the transition from neutron star spin-down to spin-up which occurred at about the same time. Smoothed particle hydrodynamic simulations of the effect of adding matter with opposite angular momentum to an existing disk, show that it is possible for a number of concentric rings with alternating senses of rotation to co-exist in a disk. This could provide an explanation for the step-like changes in Ṗ which are observed in GX 1+4. Changes at the inner boundary of the disk occur at the same timescale as that imposed at the outer boundary. Reversals of material torque on the neutron star occur at a minimum in LX.
Radio Sources in the 2dF Galaxy Redshift Survey I. Radio Source Populations
Authors: Sadler Elaine M. , McIntyre V. J. , Jackson C. A. , Cannon R. D.
Published: March 2011

We present the first results from a study of the radio continuum properties of galaxies in the 2dF Galaxy Redshift Survey, (2dFGRS) based on thirty 2dF fields covering a total area of about 100 deg2. About 1·5% of galaxies with bJ < 19·4 mag. are detected as radio continuum sources in the NRAO VLA Sky Survey (NVSS). Of these, roughly 40% are star-forming galaxies and 60% are active galaxies (mostly low-power radio galaxies and a few Seyferts). The combination of 2dFGRS and NVSS will eventually yield a homogeneous set of around 4000 radio-galaxy spectra, which will be a powerful tool for studying the distribution and evolution of both AGN and starburst galaxies out to z ∼ 0·3.
Near-infrared Integral-Field Spectrograph (NIFS): An Instrument Proposed for Gemini
Authors: McGregor Peter J. , Conroy Peter , Bloxham Gabe , van Harmelen Jan
Published: March 2011

In late 1998 the International Gemini Project Office identified a need for a low cost, near-infrared spectrograph to be commissioned on the Gemini South telescope on the shortest possible timescale. In response, the Research School of Astronomy and Astrophysics of the Australian National University proposed to design, construct, and commission a near-infrared, integral-field spectrograph on Gemini. The science drivers and novel design of the Near-infrared Integral-Field Spectrograph (NIFS) are described in this paper. NIFS will achieve significant economies in cost and schedule in several ways:

• By addressing targeted science with high efficiency. NIFS will primarily target velocity measurements in galaxies to study the demographics of black holes in galactic nuclei and the evolution of structural properties in high redshift galaxies. However, NIFS will also be applied to a wide range of general astronomical topics, but these will not dictate the instrument design.

• By adopting a largely fixed-format design. A 3·2″ × 3·2″ ‘stair-case’ integral field unit (IFU) will feed a near-infrared spectrograph with four fixed-angle gratings mounted on a single grating wheel. A single, fixed-format camera will form the spectral image on a 2048 × 2048 Rockwell HgCdTe HAWAII-2 array. Two-pixel spectral resolving powers of ∼5400 will be achieved with complete wavelength coverage in each of the J, H, and K photometric bands through 32 optimally sampled 0·1″ wide slitlets. The velocity resolution of ∼55 km s−1 will be sufficient to achieve the targeted science objectives, and will allow software rejection of OH airglow lines.

• By packaging the NIFS instrument within a duplicate of the Near-Infrared Imager (NIRI) cryostat. The NIRI cryostat, On-Instrument Wavefront Sensor (OIWFS), detector focusing mechanism, control system, and EPICS software will all be duplicated with only minimal change. Construction of the duplicate NIRI cryostat, OIWFS, and control system will be done by the University of Hawaii.
The Introduction of Tech Pan Film at the UK Schmidt Telescope
Authors: Parker Quentin A. , Malin David
Published: March 2011

Kodak Technical Pan (Tech Pan) emulsion on a film base has been in use at the UK Schmidt Telescope (UKST) since 1992. This material is extremely fine grained and its resolution is well matched to images produced by the UKST under good conditions. Tech Pan yields wide-angle photographs that are about 1 (stellar) magnitude fainter than equivalent IIIa-F plates but have considerably lower grain noise. A wide variety of new projects are under way which take advantage of this remarkable material. In this paper empirical results from experiments with Tech Pan from a number of sources are tied in with UKST experience to present an overview of the properties of the emulsion from an astronomical perspective. We compare Tech Pan's properties with those of equivalent IIIa-F emulsion, to which it seems superior in almost every respect. This overview and groundwork are currently missing from the published astronomical literature. The technical background and developments leading to adoption of this material at the UKST are presented.
Effectiveness of the photochemical reflectance index to track photosynthetic activity over a range of forest tree species and plant water statuses
Authors: Ripullone F. , Rivelli A. R. , Baraldi R. , Guarini R. , Guerrieri R. , Magnani F. , Peñuelas J. , Raddi S. , Borghetti M.
Published: March 2011

In this study, we investigated the potential of the photochemical resistance index (PRI) to track photosynthetic activity under water stress conditions by measuring PRI, leaf fluorescence, the xanthophyll cycle and photosynthetic activity in different forest tree species subjected to progressive drought. The PRI declined with pre-dawn water potential and a significant relationship between PRI and the xanthophyll de-epoxidation state (DEPS) was observed, although with large interspecific variability in the sensitivity of PRI to changes in DEPS. For single tree species, a strong relationship was observed on either PRI light saturated photosynthesis or PRI maximum photochemical efficiency of PSII (ΔF/Fm′); a larger variability in both relationships was apparent when data from different species were pooled together. However, an improved correlation was shown only in the former relationship by plotting the ΔPRI (dawn PRI minus the midday PRI values). Thus, we conclude that PRI is able to provide a good estimate of maximum CO2 assimilation at saturating light and ΔF/Fm′ for single tree species, despite the severe drought conditions applied. PRI should be applied more cautiously when dealing with multispecific forests because of confounding factors such as the strong interspecific differences in the initial value of PRI and in the sensitivity of PRI to changes in DEPS in response to drought.
The continuous accumulation of Na+ in detached leaf sections is associated with over-expression of NTHK1 and salt tolerance in poplar plants
Authors: Zhang Ying , Yang Ying-Xia , Zhou Xiangming , Jia Yan-Hong , Nie Li-Li , Zhang Yue , Chen Shou-Yi , Wang Jing-An , Liu Zhong-Qi
Published: March 2011

Detached leaf sections (2 × 2 cm2) from transgenic poplar line 18-1 and its wild type (WT) (Populus × euramericana ‘Neva’) were used to test their salt tolerance and gene expression under controlled environment conditions. The sections from line 18-1 displayed better tolerance to NaCl stress, indicated by high chlorophyll retention and K+ content but low relative electrolyte leakage (REL). Transient overexpression of NTHK1 (Nicotiana tabacum histidine kinase 1) and V-H+-PPase was found in the detached young leaves from line 18-1 after they had been stressed for a few minutes. The activities of vacuolar-type H+-ATPase and H+-PPase in line 18-1 were boosted initially and then decreased to normal level as in unstressed leaves. After sections were stressed for 10 days, the maximal Na+ concentration in line 18-1 was much higher than that in the WT. The higher capacity for Na+ accumulation in line 18-1 may be due to stable Na+ sequestration into the vacuoles. Osmotic stress imposed little effect on REL and chlorophyll content of the sections. The capacity of detached leaf sections in NaCl solution to tolerate stress and to accumulate Na+ may be useful for identifying genotypes with good salt tolerance in poplar and other plants.
Spatial cyberinfrastructures, ontologies, and the humanities
Authors: Sieber Renee E. , Wellen Christopher C. , Jin Yuan
Published: March 2011

We report on research into building a cyberinfrastructure for Chinese biographical and geographic data. Our cyberinfrastructure contains (
i
) the McGill-Harvard-Yenching Library Ming Qing Women's Writings database (MQWW), the only online database on historical Chinese women's writings, (
ii
) the China Biographical Database, the authority for Chinese historical people, and (
iii
) the China Historical Geographical Information System, one of the first historical geographic information systems. Key to this integration is that linked databases retain separate identities as bases of knowledge, while they possess sufficient semantic interoperability to allow for multidatabase concepts and to support cross-database queries on an ad hoc basis. Computational ontologies create underlying semantics for database access. This paper focuses on the spatial component in a humanities cyberinfrastructure, which includes issues of conflicting data, heterogeneous data models, disambiguation, and geographic scale. First, we describe the methodology for integrating the databases. Then we detail the system architecture, which includes a tier of ontologies and schema. We describe the user interface and applications that allow for cross-database queries. For instance, users should be able to analyze the data, examine hypotheses on spatial and temporal relationships, and generate historical maps with datasets from MQWW for research, teaching, and publication on Chinese women writers, their familial relations, publishing venues, and the literary and social communities. Last, we discuss the social side of cyberinfrastructure development, as people are considered to be as critical as the technical components for its success.
The Briançon-Skoda theorem and coefficient ideals for non-𝔪-primary ideals
Authors: Aberbach Ian , Hosry Aline
Published: March 2011

We generalize a Briançon-Skoda type theorem first studied by Aberbach and Huneke. With some conditions on a regular local ring

(
R
,

m

)

(R,\mathfrak {m})

containing a field, and an ideal

I
I

of

R
R

with analytic spread

ℓ
\ell

and a minimal reduction

J
J

, we prove that for all

w
≥
−
1

w \geq -1

,

I

ℓ
+
w

¯

⊆

J

w
+
1

a

(
I
,
J
)
,

\overline {I^{\ell +w}} \subseteq J^{w+1} \mathfrak {a} (I,J),

where

a

(
I
,
J
)

\mathfrak {a}(I,J)

is the coefficient ideal of

I
I

relative to

J
J

, i.e. the largest ideal

b

\mathfrak {b}

such that

I

b

=
J

b

I\mathfrak {b}=J\mathfrak {b}

. Previously, this result was known only for

m

\mathfrak {m}

-primary ideals.
Multi-point variations of the Schwarz lemma with diameter and width conditions
Authors: Betsakos Dimitrios
Published: March 2011

Suppose that

f
f

is holomorphic in the unit disk

D

\mathbb D

and

f
(

D

)
⊂

D

f(\mathbb D)\subset \mathbb D

,

f
(
0
)
=
0

f(0)=0

. A classical inequality due to Littlewood generalizes the Schwarz lemma and asserts that for every

w
∈
f
(

D

)

w\in f(\mathbb D)

, we have

|

w

|

≤

∏
j

|

z
j

(
w
)

|

|w|\leq \prod _j |z_j(w)|

, where

z
j

(
w
)

z_j(w)

is the sequence of pre-images of

w
w

. We prove a similar inequality by replacing the assumption

f
(

D

)
⊂

D

f(\mathbb D)\subset \mathbb D

with the weaker assumption Diam

f
(

D

)
=
2

f(\mathbb D)=2

. This inequality generalizes a growth bound involving only one pre-image, proven recently by Burckel et al. We also prove growth bounds for holomorphic

f
f

mapping

D

\mathbb D

onto a region having fixed horizontal width. We give a complete characterization of the equality cases. The main tools in the proofs are the Green function and the Steiner symmetrization.
Genetic variation in a tropical tree species influences the associated epiphytic plant and invertebrate communities in a complex forest ecosystem
Authors: Zytynska Sharon E. , Fay Michael F. , Penney David , Preziosi Richard F.
Published: March 2011

Genetic differences among tree species, their hybrids and within tree species are known to influence associated ecological communities and ecosystem processes in areas of limited species diversity. The extent to which this same phenomenon occurs based on genetic variation within a single tree species, in a diverse complex ecosystem such as a tropical forest, is unknown. The level of biodiversity and complexity of the ecosystem may reduce the impact of a single tree species on associated communities. We assessed the influence of within-species genetic variation in the treeBrosimum alicastrum(Moraceae) on associated epiphytic and invertebrate communities in a neotropical rainforest. We found a significant positive association between genetic distance of trees and community difference of the epiphytic plants growing on the tree, the invertebrates living among the leaf litter around the base of the tree, and the invertebrates found on the tree trunk. This means that the more genetically similar trees are host to more similar epiphyte and invertebrate communities. Our work has implications for whole ecosystem conservation management, since maintaining sufficient genetic diversity at the primary producer level will enhance species diversity of other plants and animals.
Evolution in metacommunities
Authors: Goodnight Charles J.
Published: March 2011

A metacommunity can be defined as a set of communities that are linked by migration, and extinction and recolonization. In metacommunities, evolution can occur not only by processes that occur within communities such as drift and individual selection, but also by among-community processes, such as divergent selection owing to random differences among communities in species composition, and group and community-level selection. The effect of these among-community-level processes depends on the pattern of migration among communities. Migrating units may be individuals (migrant pool model), groups of individuals (single-species propagule pool model) or multi-species associations (multi-species propagule pool model). The most interesting case is the multi-species propagule pool model. Although this pattern of migration may
a priori
seem rare, it becomes more plausible in small well-defined ‘communities’ such as symbiotic associations between two or a few species. Theoretical models and experimental studies show that community selection is potentially an effective evolutionary force. Such evolution can occur either through genetic changes within species or through changes in the species composition of the communities. Although laboratory studies show that community selection can be important, little is known about how important it is in natural populations.
Morphological, morphometric, meristic and osteological evidence for two species of hake (Actinopterygii: Gadiformes: Merluccius) in Argentinean waters
Authors: Díaz de Astarloa J. M. , Bezzi S. I. , González Castro M. , Mabragaña E. , Hernández D. , Delpiani S. M. , Figueroa D. E. , Cousseau M. B. , Deli Antoni M. Y. , Tringali L.
Published: March 2011

Morphologically, both classic and landmark‐based morphometry and meristic analyses of 241 specimens of Merluccius, along with the re‐examination of six paratype specimens of Merluccius hubbsi, the holotype and three paratypes of Merluccius patagonicus and the syntype of Merluccius australis revealed the presence of only two species of Merluccius in Argentinean waters. Internal structures (hyomandibula, urohyal and sagitta otolith) of M. hubbsi were compared to those reported for M. patagonicus and were shown to have identical morphology. Type specimens of M. patagonicus showed a complete overlap in morphometric and meristic characters with M. hubbsi, whereas M. australis had a greater number of second dorsal and anal‐fin rays, and more lateral‐line scales. In addition, M. australis had a smaller eye and longer snout than M. hubbsi and M. patagonicus. The results indicate that there is no evidence for a third hake species in Argentinean waters. Merluccius patagonicus is a synonym of M. hubbsi.
Behavioural responses of hatchery‐reared and wild codGadus morhuato mechano‐acoustic predator signals
Authors: Meager J. J. , Rodewald P. , Domenici P. , Fernö A. , Järvi T. , Skjæraasen J. E. , Sverdrup G. K.
Published: March 2011

The behavioural responses of wild (predator‐experienced) and hatchery‐reared (predator‐naive) codGadus morhuato standardized mechano‐acoustic (MA) stimuli were compared in the laboratory. Wild fish responded mainly with freezing and fast‐start escapes away from the stimulus, whereas hatchery‐reared fish often ignored or approached the stimulus. Wild fish also had stronger responses, turning faster during escapes and reducing activity immediately after the stimulus. Both fish types were less active on a ‘risky’ bare substratum after the stimulus. The antipredator responses of wild fish were consistent to repeated stimuli, whereas hatchery‐reared fish that had generally only encountered harmless stimuli showed more variable responses with lower repeatability. This suggests that experience plays a role in shaping the behavioural response of fishes to MA stimuli.
Expression of coordinately regulated defence response genes and analysis of their role in disease resistance in Medicago truncatula
Authors: SAMAC DEBORAH A. , PEÑUELA SILVIA , SCHNURR JUDY A. , HUNT E. NICOLE , FOSTER‐HARTNETT DAWN , VANDENBOSCH KATHRYN A. , GANTT J. STEPHEN
Published: March 2011

Microarray technology was used to identify the genes associated with disease defence responses in the model legume Medicago truncatula. Transcript profiles from M. truncatula cv. Jemalong genotype A17 leaves inoculated with Colletotrichum trifolii and Erysiphe pisi and roots infected with Phytophthora medicaginis were compared to identify the genes expressed in response to all three pathogens and genes unique to an interaction. The A17 genotype is resistant to C. trifolii and E. pisi, exhibiting a hypersensitive response after inoculation, and is moderately susceptible to P. medicaginis. Among the most strongly up‐regulated genes in all three interactions were those encoding a hevein‐like protein, thaumatin‐like protein (TLP) and members of the pathogenesis response (PR)10 family. Transcripts of genes for enzymes in the phenylpropanoid pathway leading to the production of isoflavonoid phytoalexins increased dramatically in response to inoculation with the foliar pathogens. In P. medicaginis‐inoculated roots, transcripts of genes in the phenylpropanoid pathway peaked at 5 days post‐inoculation, when symptoms became visible. Transcript accumulation of three PR10 family members, a TLP and chalcone synthase (CHS) was assessed in M. truncatula genotype R108 plants. The R108 plants are resistant to C. trifolii and moderately susceptible to E. pisi and P. medicaginis. Transcript accumulation paralleled the stages of pathogen development. To evaluate the role of a TLP, a PR10 family member and CHS in disease resistance, transgenic R108 plants containing interfering RNA (RNAi) constructs were produced. Reduced expression of PR10 and TLP had no effect on the disease phenotype, whereas reduced expression of CHS resulted in increased susceptibility to necrotrophic pathogens.
A novel ambulatory closed circuit breathing system for use during exercise
Authors: McMorrow R. C. N. , Windsor J. S. , Mythen M. G. , Grocott M. P. W. ,   the Caudwell Xtreme Everest Research Group
Published: March 2011

We describe a unique ambulatory closed circuit for delivering high fractions of inspired oxygen to an exercising user who does not require isolation from their environment. We describe the major components and their function and suggest potential applications for such a circuit. This circuit may benefit patients who are chronically dependant on oxygen, are unable to exercise due to hypoxia, or require oxygen supplementation at high altitude.
Measurement of carbon flux through the MEP pathway for isoprenoid synthesis by 31P‐NMR spectroscopy after specific inhibition of 2‐C‐methyl‐d‐erythritol 2,4‐cyclodiphosphate reductase. Effect of light and temperature
Authors: MONGÉLARD GAËLLE , SEEMANN MYRIAM , BOISSON ANNE‐MARIE , ROHMER MICHEL , BLIGNY RICHARD , RIVASSEAU CORINNE
Published: March 2011

The methylerythritol 4‐phosphate (MEP) and the mevalonate pathways are the unique synthesis routes for the precursors of all isoprenoids. An original mean to measure the carbon flux through the MEP pathway in plants is proposed by using cadmium as a total short‐term inhibitor of 2‐C‐methyl‐d‐erythritol 2,4‐cyclodiphosphate (MEcDP) reductase (GcpE) and measuring the accumulation rate of its substrate MEcDP by 31P‐NMR spectroscopy. The MEP pathway metabolic flux was determined in spinach (Spinacia oleracea), pea (Pisum sativum), Oregon grape (Mahonia aquifolium) and boxwood (Buxus sempervirens) leaves. In spinach, flux values were compared with the synthesis rate of major isoprenoids. The flux increases with light intensity (fourfold in the 200–1200 µmol m−2 s−1 PPFR range) and temperature (sevenfold in the 25–37 °C range). The relationship with the light and the temperature dependency of isoprenoid production downstream of the MEP pathway is discussed.