Planetary Nebula Candidates in Extragalactic Young Star Clusters

During an analysis of optical spectra of 80 young star clusters in several nearby spiral galaxies, [O III] and [N II] emission lines were noted in some cases. Three of these emission line sources are identified as likely planetary nebula (PN) candidates and may represent a rare opportunity to study PNe whose progenitor stars are known to be of intermediate masses. This paper presents and discusses basic properties of the PN candidates and their host clusters. Based on the observed emission line fluxes, the excitation parameters and luminosities of the nebulae are derived. This allows a crude placement of the central stars in two of the objects on the H-R diagram, and their temperatures and luminosities are found to be consistent with post-AGB model tracks for a central star mass of about 0.60 Msun. Host cluster ages and masses are estimated from broad-band colours and by comparison with model SSP spectra. One of the host clusters has an age of 32-65 Myrs, corresponding to a main sequence turn-off mass of M(TO) = 6.6-9.0 Msun. For the other cluster the age is 282-407 Myrs, corresponding to M(TO) = 3.2-3.6 Msun. By estimating the number of stars evolving off the main sequence per year, a total of 6 PNe are expected in our full sample of 80 clusters for aPN lifetime of 10000 years. The factor of two disagreement with the actual observed number may be due, among other things, to uncertainties in PN lifetimes. It is interesting to note that all three PN candidates are associated with clusters which are more diffuse than average. While PNe have previously been found in some old globular clusters, the candidates identified here are among the first identified in young star clusters.Comment: 10 pages, 9 figures. Accepted for publication in A&

Context dependence of the event-related brain potential associated with reward and punishment

The error-related negativity (ERN) is an event-related brain potential elicited by error commission and by presentation of feedback stimuli indicating incorrect performance. In this study, the authors report two experiments in which participants tried to learn to select between response options by trial and error, using feedback stimuli indicating monetary gains and losses. The results demonstrate that the amplitude of the ERN is determined by the value of the eliciting outcome relative to the range of outcomes possible, rather than by the objective value of the outcome. This result is discussed in terms of a recent theory that holds that the ERN reflects a reward prediction error signal associated with a neural system for reinforcement learning

Observations of mesoscale vertical velocities around frontal zones

Vertical velocity and reflectivity data obtained with a VHF Doppler radar over a 15-day period in October and November of 1981 are analyzed. Standard radiosonde data and surface observations were used to locate two occluded fronts, two warm fronts, and a cold front that passed the radar site. These fronts are also evident in the radar reflectivity data. Most studies of the vertical circulation patterns associated with mososcale systems have used precipitation and cloud formations as tracers. Unlike other observational techniques, the VHF radar permits the continuous measurement of the three-dimensional air velocity vector in time and height from a fixed location. With the beam in a vertically pointing position, signals are scattered from turbulent variations in the refractive index with half the scale of the radar wavelength and by regions with sudden changes in the refractive index associated with horizontally stratified layers. Generally, the strongest echoes occur at the maximum in the vertical gradient of refractivity, usually at the base of a temperature inversion, such as the tropopause. VHF radars can also be used to locate atmospheric fronts, which are characterized by static stability, large horizontal temperature gradients, large vorticities, and vertical wind shears. These radars can provide the velocity field data needed to study wave motions associated with fronts and compare the actual vertical circulation to theoretical predictions

Comparison of vertical velocities analyzed by a numerical model and measured by a VHF wind profiler

The use of wind profilers for measuring vertical velocities in the troposphere and lower stratosphere is potentially of great interest for verification of forecasts, diagnosis of mesoscale circulations, and studies of wave motions. The studies of profiler vertical velocities to date have shown that the observed patterns of ascent and subsidence are reasonable when compared to the synoptic conditions. However, difficulties arise when a direct verification of the profiler vertical winds is sought. Since no other technique can measure the vertical velocities over the same height range and with the same claimed accuracy as the profilers, direct comparisons are impossible. The only alternative is to compare the measurements to analyzed vertical velocity fields. Here, researchers compare vertical measurements made with the SOUSY VHF radar over a period of 11 days at the beginning of November 1981 to the analyzed vertical velocities produced by the European Center for Medium-range Weather Forecasting (ECMWF) model for grid points near the radar site

ALICE TPC control and read-out system

ALICE is a dedicated heavy-ion experiment at CERN LHC aiming to study the properties of the quark–gluon plasma. A lead– lead collision might produce several ten thousand new particles. Detailed study of the event requires precise measurements of the particle tracks. A 90 m3 Time Projection Chamber (TPC) with more than 500 000 read-out pads was built as the main central barrel tracker. Collisions can be recorded at a rate of up to about 1 kHz. The front-end electronics, designed from FPGAs and custom ASICs, performs shaping, amplification, digitisation and digital filtering of the signals. The data is forwarded to DAQ via 216 1.25 Gb/s fibre-optical links. Configuration, control and monitoring is done by an embedded Linux system on the front-end electronics. First results on the performance of the front-end electronics and the distributed detector control system are presented

Influence of Conjugated Linoliec Acid (CLA) on Belly and Bacon Quality From Pigs Fed Various Diets

A study was initiated to investigate the feeding of conjugated linoleic acid (CLA) to market barrows to achieve improvements of bacon quality characteristics. CLA was fed at 55 kg of body weight to 113 kg of body weight. CLA improved belly firmness (P\u3c0.05) for all diets according to the belly bar firmness test but CLA did not improve bacon sliceability. Bacon slabs from CLA-supplemented pigs were firmer according to the compression test. Dietary CLA increased the percentage of saturated fatty acids and CLA isomers in bacon

Suppression and triggering of Arabidopsis immunity by Albugo species

Albugo species are obligate biotrophic phytopathogens. Like other biotrophs, they are anticipated to secrete effectors that can suppress or trigger plant defenses; the nature of Albugo effectors is currently unknown. Sequencing of A. laibachii isolate Nc14 (AlNc14) genome reveals 13032 genes encoded in a ~37 Mb genome. We analyze the effector complement of AlNc14 and find known effector classes but also classes unique to A. laibachii. Experiments reveal that CHXCs are a novel class of effectors that suppress host defense. We functionally characterize two predicted AlNc14 effectors in detail; CHXC1 a potential core effector conserved in other oomycete species, and SSP6, a fast-evolving effector specific to A. laibachii. CHXC1 encodes a nuclear localized HECT E3 ligase homolog, which suppresses host defenses dependent on cys651. We find 7 variants of SSP6 that are under diversifying selection. Two highly expressed variants SSP6-2c and SSP6-A are plasma membrane localized when expressed in planta. Interestingly, SSP6-2c but not SSP6-A, is able to enhance growth of P. infestans race blue 13 and suppress flg22-dependent ROS production. In Arabidopsis cells we find SSP6-2c localizes around AlNc14 haustoria. We propose that AlNc14 secretes the effectors SSP6-2c and CHXC1 into the plant cell to suppress defense and promote infection. Current methods to screen for virulence of effector candidates predominantly rely on measuring growth of bacterial pathogens. Quantitative assessment of resistance and susceptibility to eukaryotic pathogens is more difficult. We develop a semi-automated high-throughput system for assaying Hpa growth. We investigate the genetic basis of resistance to Albugo in Arabidopsis. We find that resistance to AlNc14 is linked to RAC1 and RAC3 in Ksk-1. In contrast, resistance to A. candida Nc2 (AcNc2) is linked to WRR4 in Col-0, Col-5 and Ksk-1. A second dominant locus, WRR5a/b in Col-5 also confers resistance to AlNc2. Thus, different R-genes and presumably different effectors govern resistance to AlNc14 and AcNc2.