Line Emission in the Brightest Cluster Galaxies of the NOAO Fundamental Plane and Sloan Digital Sky Surveys

We examine the optical emission line properties of Brightest Cluster Galaxies (BCGs) selected from two large, homogeneous datasets. The first is the X-ray selected National Optical Astronomy Observatory Fundamental Plane Survey (NFPS), and the second is the C4 catalogue of optically selected clusters built from the Sloan Digital Sky Survey Data Release ~3 (SDSS DR3). Our goal is to better understand the optical line emission in BCGs with respect to properties of the galaxy and the host cluster. Throughout the analysis we compare the line emission of the BCGs to that of a control sample made of the other bright galaxies near the cluster centre. Overall, both the NFPS and SDSS show a modest fraction of BCGs with emission lines (~15%). No trend in the fraction of emitting BCGs as a function of galaxy mass or cluster velocity dispersion is found. However we find that, for those BCGs found in cooling flow clusters, 71^{+9}_{-14}% have optical emission. Furthermore, if we consider only BCGs within 50kpc of the X-ray centre of a cooling flow cluster, the emission-line fraction rises further to 100^{+0}_{-15}%. Excluding the cooling flow clusters, only ~10% of BCGs are line emitting, comparable to the control sample of galaxies. We show that the physical origin of the emission line activity varies: in some cases it has LINER-like line ratios, whereas in others it is a composite of star-formation and LINER-like activity. We conclude that the presence of emission lines in BCGs is directly related to the cooling of X-ray gas at the cluster centre.Comment: Accepted for publication in MNRAS. 13 pages mn2e style with 7 figures and 2 table

A note on Lysias 1.22

Solución de la notoria crux de Lys. 1.22, donde la mayoría de editores desde Reiske ha propuesto la existencia de una laguna. Propongo que la lectura preservada μεγλοις es una corrupción del original μν λλοις.Resolution of the notorious crux de Lys. 1.22, where the most part of Reiske’s editors have proposed the existence of a lagoon. I propose that the preserved reading μεγλοις is just a corruption of the original μν λλοις

A Melancholy Experience: William C. C. Claiborne and the Louisiana Militia, 1811-1815

William C. C. Claiborne found himself a stranger in a strange land. Almost more a colonial governor of a European power rather than an American statesman, Claiborne grappled with maintaining a militia force for the Territory of Orleans, now the present day state of Louisiana. He built upon the volunteer companies he found within the city of New Orleans, but had little success molding the entire militia into an effective, efficient military force. Claiborne, hoping to use the fear generated by the January 1811 slave revolt to spur militia reform, maintained an active correspondence with the state\u27s legislators, the area\u27s military commanders, the members of the Louisiana congressional delegation, and even the President of the United States for assistance with militia matters. Ultimately, Claiborne failed and the British attack on New Orleans in 1814/1815 made the matter of reform academic

A view from above : changing seas, seabirds and food sources

In this review we summarize what is known about mechanisms by which climate change may be affecting the populations of seabirds around the UK. Breeding success and adult survival are the key factors affecting changes in seabird populations, and food intake is implicated as a major determinant of both. The diet of most UK seabird species is almost exclusively sandeels, small clupeoid fish or zooplankton and it is clear that the marine pelagic food web is the key ecological system determining food supply. Hence, we develop the review by first considering how climate changes may affect primary production, and then examine how this propagates through the food web to zooplankton and fish culminating in fluctuations in seabird numbers. A trend of increasing numbers of many seabird species since 1970, particularly puffins, guillemots and razorbills, appears to have been reversed since 2000. The proximate cause of the recent declines seems to be a succession of 5 years of low breeding success for a range of species due to a shortage of food, especially sandeels. However, the connection with climate change remains uncertain, though there are indications that declines in the productivity of sandeel populations may be linked in some complex way to warming sea temperatures. The main conclusion is that no part of the marine food web, including fisheries, can be considered in isolation when trying to understand and predict the consequences of climate change for seabirds. Impacts can be expected in all parts of the system, and all parts of the system are interconnected

Operator Guidance Informed by AI-Augmented Simulations

This paper will present a multi-fidelity, data-adaptive approach with a Long Short-Term Memory (LSTM) neural network to estimate ship response statistics in bimodal, bidirectional seas. The study will employ a fast low-fidelity, volume-based tool SimpleCode and a higher-fidelity tool known as the Large Amplitude Motion Program (LAMP). SimpleCode and LAMP data were generated by common bi-modal, bi-directional sea conditions in the North Atlantic as training data. After training an LSTM network with LAMP ship motion response data, a sample route was traversed and randomly sampled historical weather was input into SimpleCode and the LSTM network, and compared against the higher fidelity results.Comment: Presented at the 22nd Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) in Drubeck, Germany on May 25th, 202

Observations of Short Period Mesospheric Wave Patterns: In Situ or Tropospheric Wave Generation

Near infrared images showing wave structure in the hydroxyl (OH) nightglow emission have been obtained from Maui, Hawaii during the ALOHA‐90 campaign. Analysis of two nights during this campaign (25 and 31 March) indicate extensive, highly coherent, linear wave patterns of very short apparent period (∼5 and 10 min respectively). Both displays exhibited several features characteristic of the in situ breakdown of a large scale, long period, upper atmospheric wave disturbance. Data in support of this mechanism was found by other ALOHA instruments which detected concurrent long period (1–2 hour) mesospheric wave disturbances on both occasions. However, a tropospheric source for these waves cannot be ruled out. At least on 25 March a weather front occurred at ∼1400 km range with a favourable orientation and location. Although its range was relatively large, background winds may have substantially increased the path length of the waves through the intervening atmosphere