Automatic construction of known-item finding test beds

This work is an initial study on the utility of automatically generated queries for evaluating known-item retrieval and how such queries compare to real queries. The main advantage of automatically generating queries is that for any given test collection numerous queries can be produced at minimal cost. For evaluation, this has huge ramifications as state-of-the-art algorithms can be tested on different types of generated queries which mimic particular querying styles that a user may adopt. Our approach draws upon previous research in IR which has probabilistically generated simulated queries for other purposes [2, 3]

Building simulated queries for known-item topics: an analysis using six european languages

There has been increased interest in the use of simulated queries for evaluation and estimation purposes in Information Retrieval. However, there are still many unaddressed issues regarding their usage and impact on evaluation because their quality, in terms of retrieval performance, is unlike real queries. In this paper, we focus on methods for building simulated known-item topics and explore their quality against real known-item topics. Using existing generation models as our starting point, we explore factors which may influence the generation of the known-item topic. Informed by this detailed analysis (on six European languages) we propose a model with improved document and term selection properties, showing that simulated known-item topics can be generated that are comparable to real known-item topics. This is a significant step towards validating the potential usefulness of simulated queries: for evaluation purposes, and because building models of querying behavior provides a deeper insight into the querying process so that better retrieval mechanisms can be developed to support the user

Broad expertise retrieval in sparse data environments

Expertise retrieval has been largely unexplored on data other than the W3C collection. At the same time, many intranets of universities and other knowledge-intensive organisations offer examples of relatively small but clean multilingual expertise data, covering broad ranges of expertise areas. We first present two main expertise retrieval tasks, along with a set of baseline approaches based on generative language modeling, aimed at finding expertise relations between topics and people. For our experimental evaluation, we introduce (and release) a new test set based on a crawl of a university site. Using this test set, we conduct two series of experiments. The first is aimed at determining the effectiveness of baseline expertise retrieval methods applied to the new test set. The second is aimed at assessing refined models that exploit characteristic features of the new test set, such as the organizational structure of the university, and the hierarchical structure of the topics in the test set. Expertise retrieval models are shown to be robust with respect to environments smaller than the W3C collection, and current techniques appear to be generalizable to other settings

VAChT knock-down mice show normal prepulse inhibition but disrupted long-term habituation

The neurotransmitter acetylcholine (ACh) plays a crucial role in both the central and peripheral nervous system. Central cholinergic transmission is important for cognitive functions and cholinergic disruptions have been associated with different neural disorders. We here tested the role of cholinergic transmission in basic cognitive functions, i.e. in prepulse inhibition (PPI) and short-term habituation (STH) as well as long-term habituation (LTH) of startle using mice with a 65% knockdown (KD) of the vesicular ACh transporter (VAChT). These mice are slow in refilling cholinergic synaptic transmitter vesicles, leading to a reduced cholinergic tone. Prepulse inhibition has been assumed to be mediated by cholinergic projections from the midbrain to the reticular formation. Surprisingly, PPI and STH were normal in these mice, whereas LTH was disrupted. This disruption could be rescued by pre-testing injections of the ACh esterase inhibitor galantamine, but not by post-testing injections. The lack of a PPI deficit might be because of the fact that VAChT KD mice show disruptions mainly in prolonged cholinergic activity, therefore the transient activation by prepulse processing might not be sufficient to deplete synaptic vesicles. The disruption of LTH indicates that the latter depends on a tonic cholinergic inhibition. Future experiments will address which cholinergic cell group is responsible for this effect

The Wolf-Rayet Content of M33

Wolf-Rayet stars (WRs) are evolved massive stars, and the relative number of WC-type and WN-type WRs should vary with metallicity, providing a sensitive test of stellar evolutionary theory. The observed WC/WN ratio is much higher than that predicted by theory in some galaxies but this could be due to observational incompleteness for WN-types, which have weaker lines. Previous studies of M33's WR content show a galactocentric gradient in the relative numbers of WCs and WNs, but only small regions have been surveyed with sufficient sensitivity to detect all of the WNs. Here we present a sensitive survey for WRs covering all of M33, finding 55 new WRs, mostly of WN type. Our spectroscopy also improves the spectral types of many previously known WRs, establishing in one case that the star is actually a background quasar. The total number of spectroscopically confirmed WRs in M33 is 206, a number we argue is complete to approximately 5%, with most WRs residing in OB associations, although approximately 2% are truly isolated. The WC/WN ratio in the central regions (<2 kpc) of M33 is much higher than that predicted by the current Geneva evolutionary models, while the WC/WN ratios in the outer regions are in good accord, as are the values in the SMC and LMC. The WC/WN ratio and the WC subtype distribution both argue that the oxygen abundance gradient in M33 is significantly larger than found by some recent studies, but are consistent with the two-component model proposed by Magrini et al.Comment: ApJ, in pres

Spitzer SAGE-SMC Infrared Photometry of Massive Stars in the Small Magellanic Cloud

We present a catalog of 5324 massive stars in the Small Magellanic Cloud (SMC), with accurate spectral types compiled from the literature, and a photometric catalog for a subset of 3654 of these stars, with the goal of exploring their infrared properties. The photometric catalog consists of stars with infrared counterparts in the Spitzer, SAGE-SMC survey database, for which we present uniform photometry from 0.3-24 um in the UBVIJHKs+IRAC+MIPS24 bands. We compare the color magnitude diagrams and color-color diagrams to those of the Large Magellanic Cloud (LMC), finding that the brightest infrared sources in the SMC are also the red supergiants, supergiant B[e] (sgB[e]) stars, luminous blue variables, and Wolf-Rayet stars, with the latter exhibiting less infrared excess, the red supergiants being less dusty and the sgB[e] stars being on average less luminous. Among the objects detected at 24 um are a few very luminous hypergiants, 4 B-type stars with peculiar, flat spectral energy distributions, and all 3 known luminous blue variables. We detect a distinct Be star sequence, displaced to the red, and suggest a novel method of confirming Be star candidates photometrically. We find a higher fraction of Oe and Be stars among O and early-B stars in the SMC, respectively, when compared to the LMC, and that the SMC Be stars occur at higher luminosities. We estimate mass-loss rates for the red supergiants, confirming the correlation with luminosity even at the metallicity of the SMC. Finally, we confirm the new class of stars displaying composite A & F type spectra, the sgB[e] nature of 2dFS1804 and find the F0 supergiant 2dFS3528 to be a candidate luminous blue variable with cold dust.Comment: 23 pages, 17 figures, 5 tables, accepted for publication in the Astronomical Journa

Decreasing prevalence in cerebral palsy: a multi-site European population-based study, 1980 to 2003

Aim: To monitor the trends in prevalence of cerebral palsy (CP) by birthweight in Europe, 1980 to 2003. Method: Data were collated from 20 population-based registers contributing to the Surveillance of Cerebral Palsy in Europe database. Trend analyses were conducted in four birthweight groups: 2499g (normal birthweight [NBW]). Results: The overall prevalence of CP decreased from 1.90 to 1.77 per 1000 live births, p<0.001, with a mean annual fall of 0.7% (95% confidence interval [CI] −0.3% to −1.0%). Prevalence in NBW children showed a non-significant trend from 1.17 to 0.89 per 1000 live births (p=0.22). Prevalence in MLBW children decreased from 8.5 to 6.2 per 1000 live births (p<0.001), but not linearly. Prevalence in VLBW children also declined from 70.9 to 35.9 per 1000 live births (p<0.001) with a mean annual fall of 3.4% (95% CI −2.4% to −4.3%). Prevalence in ELBW children remained stable, at a mean rate of 42.4 per 1000 live births. Interpretation: The decline in prevalence of CP in children of VLBW continues, and confirms that previously reported. For the first time, there is also a significant decline among those of MLBW, resulting in a significant overall decrease in the prevalence of CP

The VLT-FLAMES survey of massive stars: Mass loss and rotation of early-type stars in the SMC

We have studied the optical spectra of a sample of 31 O- and early B-type stars in the Small Magellanic Cloud, 21 of which are associated with the young massive cluster NGC 346. Stellar parameters are determined using an automated fitting method. Comparison with predictions of stellar evolution that account for stellar rotation does not result in a unique age, though most stars are best represented by an age of 1-3 Myr. The present day v_sini distribution of the 21 dwarf stars in our sample is consistent with an underlying rotational velocity (v_r) distribution that can be characterised by a mean velocity of about 160-190 km/s and an effective half width of 100-150 km/s. The v_r distribution must include a small percentage of slowly rotating stars. If predictions of the time evolution of the equatorial velocity for massive stars within the environment of the SMC are correct, the young age of the cluster implies that this underlying distribution is representative for the initial rotational velocity distribution. The location in the Hertzsprung-Russell diagram of the stars showing helium enrichment is in qualitative agreement with evolutionary tracks accounting for rotation, but not for those ignoring v_r. The mass loss rates of the SMC objects having luminosities of log L/L_sun > 5.4 are in excellent agreement with predictions. However, for lower luminosity stars the winds are too weak to determine M_dot accurately from the optical spectrum. Two of three spectroscopically classified Vz stars from our sample are located close to the theoretical zero age main sequence, as expected.Comment: 35 pages, accepted for publication in A&