Molecular and Ionised Gas Motions in the Compact HII region G29.96-0.02

We present a new observation of the compact HII region, G29.96-0.02, that allows us to compare the velocity structure in the ionised gas and surrounding molecular gas directly. This allows us to remove most of the remaining ambiguity about the nature of this source. In particular, the comparison of the velocity structure present in the 4S-3P HeI lines with that found in the 1-0 S(1) of molecular hydrogern convincingly rules out a bow shock as being important to the kinematics of this source. Our new observation therefore agrees with our previous conclusion, drawn from a velocity resolved HI Br gamma map, that most of the velocity structure in G29.96-0.02 can largely be explained as a result of a champagne flow model. We also find that the best simple model must invoke a powerful stellar wind to evacuate the `head' of the cometary HII region of ionised gas. However, residual differences between model and data tend to indicate that no single simple model can adequately explain all the observed features.Comment: 10 pages, 4 postscript figures. To be published in MNRA

Locally linear embedding: dimension reduction of massive protostellar spectra

We present the results of the application of locally linear embedding (LLE) to reduce the dimensionality of dereddened and continuum subtracted near-infrared spectra using a combination of models and real spectra of massive protostars selected from the Red MSX Source survey database. A brief comparison is also made with two other dimension reduction techniques; Principal Component Analysis (PCA) and Isomap using the same set of spectra as well as a more advanced form of LLE, Hessian locally linear embedding. We find that whilst LLE certainly has its limitations, it significantly outperforms both PCA and Isomap in classification of spectra based on the presence/absence of emission lines and provides a valuable tool for classification and analysis of large spectral data sets.Comment: 8 pages, 7 figures. Accepted for publication in MNRAS 2016 June 2

Infrared Helium-Hydrogen Line Ratios as a Measure of Stellar Effective Temperature

We have observed a large sample of compact planetary nebulae in the near-infrared to determine how the 2^1P-2^1S HeI line at 2.058um varies as a function of stellar effective temperature, Teff. The ratio of this line with HI Br g at 2.166um has often been used as a measure of the highest Teff present in a stellar cluster, and hence on whether there is a cut-off in the stellar initial mass function at high masses. However, recent photoionisation modelling has revealed that the behaviour of this line is more complex than previously anticipated. Our work shows that in most aspects the photoionisation models are correct. In particular, we confirm the weakening of the 2^1P-2^1S as Teff increases beyond 40000K. However, in many cases the model underpredicts the observed ratio when we consider the detailed physical conditions in the individual planetary nebulae. Furthermore, there is evidence that there is still significant 2^1P-2^1S HeI line emission even in the planetary nebulae with very hot (Teff>100000K) central stars. It is clear from our work that this ratio cannot be considered as a reliable measure of effective temperature on its own.Comment: 24 pages 11 figures (in 62 separate postscript files) Accepted for publication in Monthly Notices of the Royal Astronomical Societ

Near Infrared Spectra of Compact Planetary Nebulae

This paper continues our study of the behaviour of near infrared helium recombination lines in planetary nebula. We find that the 1.7007um 4^3D-3^3P HeI line is a good measure of the HeI recombination rate, since it varies smoothly with the effective temperature of the central star. We were unable to reproduce the observed data using detailed photoionisation models at both low and high effective temperatures, but plausible explanations for the difference exist for both. We therefore conclude that this line could be used as an indicator of the effective temperature in obscured nebula. We also characterised the nature of the molecular hydrogen emission present in a smaller subset of our sample. The results are consistent with previous data indicating that ultraviolet excitation rather than shocks is the main cause of the molecular hydrogen emission in planetary nebulae.Comment: Accepted for publication in MNRA

The Load Alternation: Semantic Shifts and Implicit Arguments

Cette étude propose que les expressions verbales du type to load, to pack, to pile, etc. sont composées de concepts substantifs spécifiques et de concepts prédicatifs généraux. Toutes ces expressions au niveau de la surface impliquent une dérivation qui combine ces éléments. Les concepts substantifs se trouvent aussi dans les expressions nominales (e.g. a load, a pack, a pile, etc.). L’alternance dans la réalisation de la structure argumentale des verbes est possible parce que l’interprétation du concept substantif subit un changement sémantique de sorte que le concept se combine différemment avec les concepts prédicatifs pertinents. Dans une réalisation, le concept substantif est le thème et dans l’autre, c’est l’argument de lieu.This study argues that verbal expressions like to load, to pack, to pile, etc. are composed of specific substantive concepts and general predicate concepts. All surface expressions involve a derivation that combines these elements. Substantive concepts may also appear in nominal expressions (e.g. a load, a pack, a pile, etc.). The verbal expressions allow an alternate realization of their argument structure because the interpretation of the substantive concept undergoes a semantic shift so that it combines differently with the pertinent predicate concepts. In one realization, the substantive concept is an implicit theme argument; in the other, it is an implicit location

On the Distribution of Determiners in Haitian Creole

Cet article fournit des données plus détaillées sur la distribution des déterminants en créole haïtien. On soutient qu’il y a deux contraintes indépendantes qui déterminent leur distribution. Comme en anglais, en hongrois, en turc et en hébreu, un déterminant spécifique est nécessaire pour la réalisation du Cas génitif en haïtien. Du reste, il y a une contrainte générale pour le traitement des catégories fonctionelles qui empêche qu’on insère deux éléments identiques dans une séquence linéaire. Cette dernière existe d’autre part dans au moins une autre langue (le fon).The paper provides more precise data on the distribution of determiners in Haitian creole. It proposes that there are two independent constraints on the distribution of these functional categories. In Haitian, as in English, Hungarian, Turkish and Hebrew, a specific determiner is necessary to the realization of genitive Case. Moreover there is a general constraint on processing which forbids the insertion of two identical functional category signals in a linear sequence. This processing constraint can be seen in at least on other language (Fon)

Motor neuron pathfinding following rhombomere reversals in the chick embryo hindbrain

Motor neurons are segmentally organised in the developing chick hindbrain, with groups of neurons occupying pairs of hindbrain segments or rhombomeres. The branchiomotor nucleus of the trigeminal nerve occupies rhombomeres 2 and 3 (r2 and r3), that of the facial nerve r4 and r5, and that of the glossopharyngeal nerve r6 and r7. Branchiomotor neuron cell bodies lie within the basal plate, forming columns on either side of the ventral midline floor plate. Axons originating in rhombomeres 2, 4 and 6 grow laterally (dorsally) towards the exit points located in the alar plates of these rhombomeres, while axons originating in odd-numbered rhombomeres 3 and 5 grow laterally and then rostrally, crossing a rhombomere boundary to reach their exit point. Examination of the trajectories of motor axons in odd-numbered segments at late stages of development (19–25) showed stereotyped pathways, in which axons grew laterally before making a sharp turn rostrally. During the initial phase of outgrowth (stage 14–15), however, axons had meandering courses and did not grow in a directed fashion towards their exit point. When r3 or r5 was transplanted with reversed rostrocaudal polarity prior to motor axon outgrowth, the majority of axons grew to their appropriate, rostral exit point, despite the inverted neuroepithelial polarity. In r3 reversals, however, there was a considerable increase in the normally small number of axons that grew out via the caudal, r4 exit point. These findings are discussed with relevance to the factors involved in motor neuron specification and axon outgrowth in the developing hindbrain

Coordination Matters : Interpersonal Synchrony Influences Collaborative Problem-Solving

The authors thank Martha von Werthern and Caitlin Taylor for their assistance with data collection, Cathy Macpherson for her assistance with the preparation of the manuscript, and Mike Richardson, Alex Paxton, and Rick Dale for providing MATLAB code to assist with data analysis. The research was funded by the British Academy (SG131613).Peer reviewedPublisher PD