3,084 research outputs found

    Depth of interocular suppression associated with continuous flash suppression, flash suppression, and binocular rivalry

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    When conflicting images are presented to the corresponding regions of the two eyes, only one image may be consciously perceived. In binocular rivalry (BR), two images alternate in phenomenal visibility; even a salient image is eventually suppressed by an image of low saliency. Recently, N. Tsuchiya and C. Koch (2005) reported a technique called continuous flash suppression (CFS), extending the suppression duration more than 10-fold. Here, we investigated the depth of this prolonged form of interocular suppression as well as conventional BR and flash suppression (FS) using a probe detection task. Compared to monocular viewing condition, CFS elevated detection thresholds more than 20-fold, whereas BR did so by 3-fold. In subsequent experiments, we dissected CFS into several components. By manipulating the number and timing of flashes with respect to the probe, we found that the stronger suppression in CFS is not due to summation between BR and FS but is caused by the summation of the suppression due to multiple flashes. Our results support the view that CFS is not a stronger version of BR but is due to the accumulated suppressive effects of multiple flashes

    Challenging the empire

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    This paper considers how Paul Gilroy transformed hitherto dominant understandings of the relationship between race and class by developing an innovative account that foregrounded questions of racist oppression and collective resistance amid the organic crisis of British capitalism. The returns from this rethinking were profound in that he was able to make transparent both the structuring power of racism within the working class, and the necessity for autonomous black resistance. At the same time, significant lacunae in his account are identified, including the neglect of the episodic emergence of working-class anti-racism and the part played by socialists, particularly those of racialized minority descent in fashioning a major anti-racist social movement. The paper concludes with a lament for the disappearance of such work informed by a ‘Marxism without guarantees’ in the contemporary field of racism studies, and asks readers to consider the gains to be derived from such a re-engagement

    Synthesis, Characterization, and Pre-Ceramic Properties of π-Conjugated Polymers Based on Ni(II) Complexes of Goedken’s Macrocycle

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    Nickel(II) complexes of Goedken’s macrocycle bearing alkyne substituents were copolymerized with 2,7-dibromo-9,9-dihexylfluorene, 2,5-dibromo-3-hexylthiophene, and 1,4-dibromo-2,5-bis(hexyloxy)benzene via microwave-induced Sonogashira cross-coupling reactions to produce copolymers 6F, 6T, and 6B. The spectroscopic and electrochemical properties of the copolymers were examined and compared to model compounds. Specifically, each polymer exhibited a nickel-based absorption centered at ca. 589 nm and two π → π* transitions between 272 and 387 nm. While the copolymers did not exhibit extended π conjugation, the nature of the organic spacer did affect the high energy transitions. Furthermore, each copolymer underwent two ligand-based one-electron oxidations at potentials of ca. 0.24 V and ca. 0.75 V relative to the ferrocene/ferrocenium redox couple. Post-polymerization functionalization of the alkyne group in 6F with Co2(CO)8 afforded a novel heterobimetallic copolymer that yielded amorphous nanomaterials containing Ni/Co when pyrolyzed at 800 °C for 3 h under an atmosphere of N2/H2 (95:5)

    Racism and anti-racism in Europe: a critical analysis of concepts and frameworks

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    The targets and expressions of racism vary across Europe. This article discusses the relevance of different descriptions and analyses of racism despite the different terms used in different countries such as ‘ethnic minority’, ‘foreigner’ or ‘black’ and different interpretations of which differences matter. It shows the significance of a cross-national European perspective on racism. There are important convergences across European countries in the discourses and practices of racism, particularly the distinction between ‘useful’ and ‘abusive’ migrants. A cross-European perspective can be an important inspiration for anti-racist struggles

    Mixed messengers, unified message: spatial grouping from temporal structure

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    AbstractIn dynamic visual environments, objects can differ from their backgrounds in terms of their associated temporal structure—the time course of changes in some stimulus property defining object and background. In a series of experiments, we investigated whether different “messengers” of temporal structure group into coherent spatial forms. Observers viewed arrays of Gabor patches in which different temporal structures designated figure and ground regions; extracting the figure required grouping across synchronized orientation, spatial frequency, phase, and/or contrast changes. Observers were able to extract spatial form from temporal structure even when information had to be combined across different messengers. Further, mixing messengers of temporal structure proved cost-free: task performance when grouping across messengers approximated performance when all information resided within a single messenger. Thus, the visual system can abstract temporal structure regardless of the messenger of the dynamic event; a coherent spatial structure emerges from this abstracted temporal structure

    Metal-containing polymers bearing pendant nickel(II) complexes of Goedken\u27s macrocycle

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    The design, synthesis, and polymerization of a norbornene-based monomer bearing a nickel(II) complex of Goedken\u27s macrocycle (endo-13) and the characterization of the resulting polymer are described. Detailed studies of the ring-opening metathesis polymerization of endo-13 using the 3-bromopyridine adduct of Grubbs\u27 3rd generation catalyst revealed that the polymerization shares many characteristics associated with a living polymer, but deviated from ideal behavior when high degrees of polymerization were targeted. The installation of a 3-hexylphenyl substituent at the macrocyclic backbone allowed for the realization of soluble polymers (14) and shut down an oxidative dimerization pathway commonly associated with metal complexes of Goedken\u27s macrocycle. The cyclic voltammogram of the polymer 14 was comprised of two one-electron oxidation waves (0.21 V and 0.70 V relative to ferrocene/ferrocenium) associated with the stepwise oxidation of the macrocyclic ligand backbone and a one electron reduction wave associated with the reduction of nickel(II) to nickel(I) (-2.07 V). Solution and solid-state UV-vis absorption spectra recorded for polymer 14 revealed a strong p®p* absorption (lmax = 390 nm) and a ligand-to-metal charge transfer band (lmax = 590 nm) typical of nickel(II) complexes of Goedken\u27s macrocycle, and confirmed the absence of macrocycle-macrocycle interactions. This work has ultimately led to the development of a controlled polymerization route to a rare example of a side-chain nickel-containing polymer with potentially useful properties