IUE observations of Fe 2 galaxies

Repeated observations of the Seyfert 1 galaxies I Zw 1 and II Zw 136, which have very strong Fe II emission lines in the optical region, were made at low resolution with the IUE Satellite. The ultraviolet spectra are very similar: both are variable and show broad emission features of Fe II (especially the UV multiplets 1, 33, 60, 62, and 63) as well as the emission lines usually strong in Seyferts and quasars. The data strongly support the hypothesis that the optical Fe II emission lines are primarily due to collisional excitation and that resonance fluorescence makes only a minor contribution to the excitation of these lines

Resolved Spectroscopy of the Narrow-Line Region in NGC 1068. I. The Nature of the Continuum Emission

We present the first long-slit spectra of the Seyfert 2 galaxy NGC 1068 obtained by the Space Telescope Imaging Spectrograph (STIS); the spectra cover the wavelength range 1150 - 10,270 Angstroms at a spatial resolution of 0.05 - 0.1 arcsec and a spectral resolving power of 1000. In this first paper, we concentrate on the far-UV to near-IR continuum emission from the continuum ``hot spot'' and surrounding regions extending out to +/- 6 arcsec (+/-432 pc) at a position angle of 202 degrees In addition to the broad emission lines detected by spectropolarimetry, the hot spot shows the ``little blue bump'' in the 2000 - 4000 Ang. range, which is due to Fe II and Balmer continuum emission. The continuum shape of the hot spot is indistinguishable from that of NGC 4151 and other Seyfert 1 galaxies. Thus, the hot spot is reflected emission from the hidden nucleus, due to electron scattering (as opposed to wavelength-dependent dust scattering). The hot spot is ~0.3 arcsec in extent and accounts for 20% of the scattered light in the inner 500 pc. We are able to deconvolve the extended continuum emission in this region into two components: electron-scattered light from the hidden nucleus (which dominates in the UV) and stellar light (which dominates in the optical and near-IR). The scattered light is heavily concentrated towards the hot spot, is stronger in the northeast, and is enhanced in regions of strong narrow-line emission. The stellar component is more extended, concentrated southwest of the hot spot, dominated by an old (> 2 x 10 Gyr) stellar population, and includes a nuclear stellar cluster which is ~200 pc in extent.Comment: 32 pages, Latex, includes 11 figures (postscript), to appear in the Astrophysical Journa

Genomic alterations in primary gastric adenocarcinomas correlate with clinicopathological characteristics and survival.

Background & aimsPathogenesis of gastric cancer is driven by an accumulation of genetic changes that to a large extent occur at the chromosomal level. In order to investigate the patterns of chromosomal aberrations in gastric carcinomas, we performed genome-wide microarray based comparative genomic hybridisation (microarray CGH). With this recently developed technique chromosomal aberrations can be studied with high resolution and sensitivity.MethodsArray CGH was applied to a series of 35 gastric adenocarcinomas using a genome-wide scanning array with 2275 BAC and P1 clones spotted in triplicate. Each clone contains at least one STS for linkage to the sequence of the human genome. These arrays provide an average resolution of 1.4 Mb across the genome. DNA copy number changes were correlated with clinicopathological tumour characteristics as well as survival.ResultsAll thirty-five cancers showed chromosomal aberrations and 16 of the 35 tumours showed one or more amplifications. The most frequent aberrations are gains of 8q24.2, 8q24.1, 20q13.12, 20q13.2, 7p11.2, 1q32.3, 8p23.1-p23.3, losses of 5q14.1, 18q22.1, 19p13.12-p13.3, 9p21.3-p24.3, 17p13.1-p13.3, 13q31.1, 16q22.1, 21q21.3, and amplifications of 7q21-q22, and 12q14.1-q21.1. These aberrations were correlated to clinicopathological characteristics and survival. Gain of 1q32.3 was significantly correlated with lymph node status (p=0.007). Tumours with loss of 18q22.1, as well as tumours with amplifications were associated with poor survival (p=0.02, both).ConclusionsMicroarray CGH has revealed several chromosomal regions that have not been described before in gastric cancer at this frequency and resolution, such as amplification of at 7q21-q22 and 12q14.1-q21.1, as well gains at 1q32.3, 7p11.2, and losses at 13q13.1. Interestingly, gain of 1q32.3 and loss of 18q22.1 are associated with a bad prognosis indicating that these regions could harbour gene(s) that may determine aggressive tumour behaviour and poor clinical outcome

Extended polarized semiclassical model for quantum-dot cavity QED and its application to single-photon sources

We present a simple extension of the semi-classical model for a two-level system in a cavity, in order to incorporate multiple polarized transitions, such as those appearing in neutral and charged quantum dots (QDs), and two nondegenerate linearly polarized cavity modes. We verify the model by exact quantum master equation calculations, and experimentally using a neutral QD in a polarization non-degenerate micro-cavity, in both cases we observe excellent agreement. Finally, the usefulness of this approach is demonstrated by optimizing a single-photon source based on polarization postselection, where we find an increase in the brightness for optimal polarization conditions as predicted by the model.Comment: 8 pages, for simple code see https://doi.org/10.5281/zenodo.347666

Pilot experiment with the aim to reduce salmonella prevalence in pork by logistic slaughter of pigs

A pilot experiment was carried out with the aim to evaluate the possibilities and results of logistic slaughter of pigs (separate slaughter of salmonella-free and salmonella-infected pig herds) under usual circumstances in a Dutch slaughterhouse. During the experiment salmonella-free herds were delivered and slaughtered on Tuesday mornings. Herds delivered on Thursday mornings served as a control group. No significant difference could be found in the number of salmonella-positive carcasses on Tuesdays and Thursdays. This was mainly caused by contamination of carcasses by contaminated slaughter equipment; 80% of all salmonella strains on carcasses were equal to strains isolated from slaughter equipment. If these salmonella strains were not included in the results, logistic slaughter did result in a significantly lower prevalence of salmonella on carcasses on Tuesdays. It was concluded that separate slaughter of salmonella free pig herds can result in a lower salmonella prevalence on carcasses, but only if slaughter hygiene and especially cleaning and disinfection before and during processing will be improved

Comparison of an excision and a sponge sampling method for measuring salmonella contamination of pig carcasses

The aim of this study was to determine if an excision sampling method and a sponge sampling method give comparable results when trying to isolate salmonella from pig carcasses. During ten sampling days in one abattoir in total 312 carcasses were sampled; each carcass was sampled with both sampling methods to get paired observations. The number of salmonella positive excision samples (31 of 312) was significantly higher (P=0.00013) than the number of salmonella positive sponge samples (9 of 312). Sensitivity of the sponge method compared to the excision method was 6.5% and the comparability of both tests was low (kappa value was 0.08). As it seems that salmonella contamination levels of fresh pork are highly underestimated with the actually used sampling methods, the authors recommend that EU-authorities prescribe a destructive salmonella test for monitoring pig carcasses after slaughter in all EU-countries or a swab/sponge method with a comparable sensitivity

Solution of the 2-star model of a network

The p-star model or exponential random graph is among the oldest and best-known of network models. Here we give an analytic solution for the particular case of the 2-star model, which is one of the most fundamental of exponential random graphs. We derive expressions for a number of quantities of interest in the model and show that the degenerate region of the parameter space observed in computer simulations is a spontaneously symmetry broken phase separated from the normal phase of the model by a conventional continuous phase transition.Comment: 5 pages, 3 figure