Binocular contrast interactions:Dichoptic masking is not a single process

To decouple interocular suppression and binocular summation we varied the relative phase of mask and target in a 2IFC contrast-masking paradigm. In Experiment I, dichoptic mask gratings had the same orientation and spatial frequency as the target. For in-phase masking, suppression was strong (a log-log slope of ∼1) and there was weak facilitation at low mask contrasts. Anti-phase masking was weaker (a log-log slope of ∼0.7) and there was no facilitation. A two-stage model of contrast gain control [Meese, T.S., Georgeson, M.A. and Baker, D.H. (2006). Binocular contrast vision at and above threshold. Journal of Vision, 6: 1224-1243] provided a good fit to the in-phase results and fixed its free parameters. It made successful predictions (with no free parameters) for the anti-phase results when (A) interocular suppression was phase-indifferent but (B) binocular summation was phase sensitive. Experiments II and III showed that interocular suppression comprised two components: (i) a tuned effect with an orientation bandwidth of ∼±33° and a spatial frequency bandwidth of >3 octaves, and (ii) an untuned effect that elevated threshold by a factor of between 2 and 4. Operationally, binocular summation was more tightly tuned, having an orientation bandwidth of ∼±8°, and a spatial frequency bandwidth of ∼0.5 octaves. Our results replicate the unusual shapes of the in-phase dichoptic tuning functions reported by Legge [Legge, G.E. (1979). Spatial frequency masking in human vision: Binocular interactions. Journal of the Optical Society of America, 69: 838-847]. These can now be seen as the envelope of the direct effects from interocular suppression and the indirect effect from binocular summation, which contaminates the signal channel with a mask that has been suppressed by the target. © 2007 Elsevier Ltd. All rights reserved.

Differential localization of GABAA receptor subunits in relation to rat striatopallidal and pallidopallidal synapses

As a central integrator of basal ganglia function, the external segment of the globus pallidus (GP) plays a critical role in the control of voluntary movement. The GP is composed of a network of inhibitory GABA-containing projection neurons which receive GABAergic input from axons of the striatum (Str) and local collaterals of GP neurons. Here, using electrophysiological techniques and immunofluorescent labeling we have investigated the differential cellular distribution of a1, a2 and a3 GABAA receptor subunits in relation to striatopallidal (Str-GP) and pallidopallidal (GP-GP) synapses. Electrophysiological investigations showed that zolpidem (100 nm; selective for the a1 subunit) increased the amplitude and the decay time of both Str-GP and GP-GP IPSCs, indicating the presence of the a1 subunits at both synapses. However, the application of drugs selective for the a2, a3 and a5 subunits (zolpidem at 400 nm, L-838,417 and TP003) revealed differential effects on amplitude and decay time of IPSCs, suggesting the nonuniform distribution of non-a1 subunits. Immunofluorescence revealed widespread distribution of the a1 subunit at both soma and dendrites, while double- and triple-immunofluorescent labeling for parvalbumin, enkephalin, gephyrin and the ?2 subunit indicated strong immunoreactivity for GABAAa3 subunits in perisomatic synapses, a region mainly targeted by local axon collaterals. In contrast, immunoreactivity for synaptic GABAAa2 subunits was observed in dendritic compartments where striatal synapses are preferentially located. Due to the kinetic properties which each GABAAa subunit confers, this distribution is likely to contribute differentially to both physiological and pathological patterns of activity.

Autonomic response in depersonalisation disorder

Background Emotional-processing inhibition has been suggested as a mechanism underlying some of the clinical features of depersonalization and/or derealization. In this study, we tested the prediction that autonomic response to emotional stimuli would be reduced in patients with depersonalization disorder. Methods The skin conductance responses of 15 patients with chronic depersonalization disorder according to DSM-IV, 15 controls, and 11 individuals with anxiety disorders according to DSM-IV, were recorded in response to nonspecific elicitors (an unexpected clap and taking a sigh) and in response to 15 randomized pictures with different emotional valences: 5 unpleasant, 5 pleasant, and 5 neutral. Results The skin conductance response to unpleasant pictures was significantly reduced in patients with depersonalization disorder (magnitude of 0.017 µsiemens in controls and 0.103 µsiemens in patients with anxiety disorders; P = .01). Also, the latency of response to these stimuli was significantly prolonged in the group with depersonalization disorder (3.01 seconds compared with 2.5 and 2.1 seconds in the control and anxiety groups, respectively; P = .02). In contrast, latency to nonspecific stimuli (clap and sigh) was significantly shorter in the depersonalization and anxiety groups (1.6 seconds) than in controls (2.3 seconds) (P = .03). Conclusions In depersonalization disorder, autonomic response to unpleasant stimuli is reduced. The fact that patients with depersonalization disorder respond earlier to a startling noise suggests that they are in a heightened state of alertness and that the reduced response to unpleasant stimuli is caused by a selective inhibitory mechanism on emotional processing.

Whither human capital? The woeful tale of transition to tertiary education in India

In this article, we examine the issue of high dropout rates in India which has adverse implications for human capital formation and hence for the country's long-term growth potential. Using the 2004–2005 National Sample Survey (NSS) employment–unemployment data, we estimate transition probabilities of moving from a number of different educational levels to higher educational levels using a sequential logit model. Our results suggest that the overall probability of reaching tertiary education is very low. Further, even by the woeful overall standards, women are significantly worse off, particularly in rural areas.

Vulnerability and disobedience:new repertoires in French environmental protests

The emergence of the counter-globalisation movement in France has been accompanied by an apparent diversification of social protest repertoires. Protest events carried out by groups associated with a wide array of issues have been remarkable for their use of spectacular and novel actions, while civil disobedience campaigns have been prominent features of environmental and civil rights protests in particular. Drawing on a number of examples of contemporary environmental and global justice campaigns, opposing advertising, four-wheeled drive vehicles, nuclear energy and, especially, open field trials of genetically modified crops, this article discusses the rise of such new forms of protest, placing them in the wider context of transformations in protest repertoires in France. It identifies key examples of innovation, before discussing the twin processes of diffusion and domestication that shape them. It is argued that, although transnational agents and processes are key determinants of repertoire innovation, it is vital to identify the national, movement and sectoral contexts and discourses which enable the naturalisation and legitimisation of new action forms.

574-647 nm wavelength tuning by second-harmonic generation from diode-pumped PPKTP waveguides

We present a compact, all-room-temperature continuous-wave laser source in the visible spectral region between 574 and 647 nm by frequency doubling of a broadly tunable InAs/GaAs quantum-dot external-cavity diode laser in a periodically poled potassium titanyl phosphate crystal containing three waveguides with different cross-sectional areas (4 × 4, 3 × 5, and 2 μm × 6 μm). The influence of a waveguide's design on tunability, output power, and mode distribution of second-harmonic generated light, as well as possibilities to increase the conversion efficiency via an optimization of a waveguide's cross-sectional area, was systematically investigated. A maximum output power of 12.04 mW with a conversion efficiency of 10.29% at 605.6 nm was demonstrated in the wider waveguide with the cross-sectional area of 4 μm × 4 μm.

Advocacy coalitions:influencing the policy process in the EU

The aim of this contribution is to critically evaluate one of the theoretical approaches used to study the European Union (EU) political system and interest groups activity: the advocacy coalition framework (ACF). ACF considers that the outcome of legislative procedures is influenced by the alignment and role played by advocacy coalitions. This contribution assesses the impact of ACF on our understanding of the influences on the EU policy processes, highlighting the strengths and weaknesses of the approach. The main argument is that the ACF, although very useful in studying the EU political system, shows shortcomings when applied to the study of EU interest groups' performance. The contribution ends with a consideration of future directions for theoretical and empirical ACF research, alone and as part of wider integrated theoretical approaches to understanding the dynamics of influence in the EU. © 2013 Copyright Taylor and Francis Group, LLC.

Overcoming bottlenecks in the membrane protein structural biology pipeline

Membrane proteins account for a third of the eukaryotic proteome, but are greatly under-represented in the Protein Data Bank. Unfortunately, recent technological advances in X-ray crystallography and EM cannot account for the poor solubility and stability of membrane protein samples. A limitation of conventional detergent-based methods is that detergent molecules destabilize membrane proteins, leading to their aggregation. The use of orthologues, mutants and fusion tags has helped improve protein stability, but at the expense of not working with the sequence of interest. Novel detergents such as glucose neopentyl glycol (GNG), maltose neopentyl glycol (MNG) and calixarene-based detergents can improve protein stability without compromising their solubilizing properties. Styrene maleic acid lipid particles (SMALPs) focus on retaining the native lipid bilayer of a membrane protein during purification and biophysical analysis. Overcoming bottlenecks in the membrane protein structural biology pipeline, primarily by maintaining protein stability, will facilitate the elucidation of many more membrane protein structures in the near future.