Energy selection experiments: The total phosphorescence spectrum of 1,4-diazatriphenylene

Shifts of object-based attention (OBA) are affected by object closure in the double-rectangle cueing paradigm (Marino & Scholl, 2005). The effect of closure on object-based selection and attentional filtering strength have not previously been investigated. Using a modified flanker paradigm (Eriksen & Eriksen, 1974), we presented subjects either a set of vertically oriented rectangles (rectangle condition) or those same rectangles with the horizontal top/bottom of each rectangle removed (line condition). In Experiments 1 & 2, a centrally presented object was flanked by four identical objects. One end of the central (target containing) object was then exogenously cued. Subjects performed a letter discrimination task on a color singleton target letter appearing on the central object in the presence of flanker letters (on flanking objects) that were either compatible or incompatible with the target response. Experiment 1 (homogeneously rectangle or line objects) showed that OBA selection is strong when objects are closed, preventing flankers from influencing performance. Experiment 2 (spatial attention control) showed that closure does not affect performance without OBA selection. Experiments 3 (flanking line objects) and 4 (flanking rectangle objects) showed that both target & flanking objects play a role in attentional filtering of distracters. During object-based attentional selection, flanking (non-selected) perceptual objects may serve to confine the effects of distracters while target (selected) perceptual objects may serve to shield the target from the effects of distracters.

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A SIMULATION STUDY OF TRUNCATION SELECTION FOR A QUANTITATIVE TRAIT OPPOSED BY NATURAL SELECTION

Genetics ◽

10.1093/genetics/94.4.989 ◽

1980 ◽

Vol 94 (4) ◽

pp. 989-1000

Author(s):

Francis Minvielle

Keyword(s):

Natural Selection ◽

Artificial Selection ◽

Random Mating ◽

Selection Response ◽

Quantitative Character ◽

Mass Selection ◽

Frequency Selection ◽

Selection Experiments ◽

Selection For ◽

Selective Process

ABSTRACT A quantitative character controlled at one locus with two alleles was submitted to artificial (mass) selection and to three modes of opposing natural selection (directional selection, overdominance and underdominance) in a large random-mating population. The selection response and the limits of the selective process were studied by deterministic simulation. The lifetime of the process was generally between 20 and 100 generations and did not appear to depend on the mode of natural selection. However, depending on the values of the parameters (initial gene frequency, selection intensity, ratio of the effect of the gene to the environmental standard deviation, fitness values) the following outcomes of selection were observed: fixation of the allele favored by artificial selection, stable nontrivial equilibrium, unstable equilibrium and loss of the allele favored by artificial selection. Finally, the results of the simulation were compared to the results of selection experiments.

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Requirement for HLA-DR+ accessory cells in natural killing of cytomegalovirus-infected fibroblasts.

Journal of Experimental Medicine ◽

10.1084/jem.164.1.180 ◽

1986 ◽

Vol 164 (1) ◽

pp. 180-195 ◽

Cited By ~ 68

Author(s):

S Bandyopadhyay ◽

B Perussia ◽

G Trinchieri ◽

D S Miller ◽

S E Starr

Keyword(s):

Negative Selection ◽

Target Cells ◽

Nk Activity ◽

Ifn Alpha ◽

Accessory Function ◽

Hla Dr ◽

Erythroleukemia Cells ◽

Accessory Cells ◽

Selection Experiments

The role of HLA-DR+ cells in NK activity against CMV-infected FS4 foreskin fibroblasts and K562 erythroleukemia cells was examined. When nonadherent PBMC were depleted of either HLA-DR+ or Leu-11b+ cells by treatment with mAbs plus C, NK activity against CMV-FS4 target cells was markedly reduced. In contrast, depletion of HLA-DR+ cells had no effect on NK activity against K562 target cells. When HLA-DR-depleted cells were added to Leu-11b-depleted cells, NK activity against CMV-FS4 was restored. Negative selection experiments indicated that the HLA-DR+ cells contributing to NK activity against CMV-FS4 are not B or T cells, while negative and positive selection experiments excluded a role for monocytes. Experiments in which HLA-DR- and Leu-11b- cells were mixed in varying proportions indicated that NK(CMV-FS4) is mediated by Leu-11b+ cells, while HLA-DR+ cells provide an accessory function. Irradiation (50 GY) abolished the NK effector function of Leu-11b+ cells, but not the accessory function of HLA-DR+ cells. The NK activity against CMV-FS4 of HLA-DR- cells was restored by the addition of rIFN-alpha or of cell-free supernatants generated by coculturing PBMC or Leu-11b- cells with CMV-FS4. The ability of these supernatants to restore NK activity of HLA-DR- cells was completely abrogated by the addition of neutralizing amounts of antibody to IFN-alpha. In related experiments, neutralization of IFN-alpha in NK assays had little or no effect on NK activity against CMV-FS4, suggesting that the accessory function of HLA-DR+ cells might be mediated by alternative mechanisms in addition to the secretion of extracellular IFN-alpha.

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