Marx and the mirage of change: Notes from South Africa

There is little doubt that the understanding of the dynamics of capitalism has been enriched by Geography. Moreover, geographers utilizing Marxist/Marxian lenses have provided valuable insights into the spatial content of the system. Over the past two decades or so, geographers in no small way have contributed to the demystification of capitalism/capitalist development in its neoliberal incarnation – change as mirage. Furthermore, poverty, inequality, unemployment and related social ills are directly linked to the system. Indeed, they are produced by the system. In this paper, the geographical evolution of the capitalist system in South Africa is examined. Critical thinkers, among them Marxists, influenced the theorization of the relationship(s) between capitalism, apartheid, class and race. In this paper, I focus on the spatial aspects, which in my view have been neglected. I reflect on various historical periods – the apartheid era and the post-apartheid era, in particular. What is apparent is that neoliberalism in South Africa has entered a phase which I label “accumulation by corrupt means”. The class basis of this strategy is examined. Critical (Marxist) geographers are shaped by the direct experiences of material conditions. I describe my experiences in this regard.

An Improved Version of the Generalized Laplacian Pyramid Algorithm for Pansharpening

The spatial resolution of multispectral data can be synthetically improved by exploiting the spatial content of a companion panchromatic image. This process, named pansharpening, is widely employed by data providers to augment the quality of images made available for many applications. The huge demand requires the utilization of efficient fusion algorithms that do not require specific training phases, but rather exploit physical considerations to combine the available data. For this reason, classical model-based approaches are still widely used in practice. We created and assessed a method for improving a widespread approach, based on the generalized Laplacian pyramid decomposition, by combining two different cost-effective upgrades: the estimation of the detail-extraction filter from data and the utilization of an improved injection scheme based on multilinear regression. The proposed method was compared with several existing efficient pansharpening algorithms, employing the most credited performance evaluation protocols. The capability of achieving optimal results in very different scenarios was demonstrated by employing data acquired by the IKONOS and WorldView-3 satellites.

Chromatic micromaps in primary visual cortex

The clustering of neurons with similar response properties is a conspicuous feature of neocortex. In primary visual cortex (V1), maps of several properties like orientation preference are well described, but the functional architecture of color, central to visual perception in trichromatic primates, is not. Here we used two-photon calcium imaging in macaques to examine the fine structure of chromatic representation and found that neurons responsive to spatially uniform, chromatic stimuli form unambiguous clusters that coincide with blobs. Further, these responsive groups have marked substructure, segregating into smaller ensembles or micromaps with distinct chromatic signatures that appear columnar in upper layer 2/3. Spatially structured chromatic stimuli revealed maps built on the same micromap framework but with larger subdomains that go well beyond blobs. We conclude that V1 has an architecture for color representation that switches between blobs and a combined blob/interblob system based on the spatial content of the visual scene.

Genre, “Apocalypse,” and the Gospel of John

Comparing the Gospel of John with Jewish apocalypses requires some understanding of what an apocalypse is. This chapter discusses contemporary understandings of what genre is and how it is determined by readers and authors. Recent genre studies have shown that humans categorize things in relation to cognitive prototypes (i.e., how closely something relates to a prototypical example). The Semeia 14 definition of “apocalypse” functions as a prototype definition, especially with its underlying “master-paradigm.” The genre of apocalypse should not be determined only by eschatological content but also by its revelatory form, spatial content, and function. The Gospel of John has been noted to share some similarities with Jewish apocalypses, but the most methodologically sound way of comparing John’s apocalyptic characteristics is to compare the Fourth Gospel with the genre of apocalypse.

Hippocampal replay of experience at real-world speeds

Representations of past and possible future experiences play a critical role in memory and decision-making processes. The hippocampus expresses these types of representations during sharp-wave ripple (SWR) events, and previous work identified a minority of SWRs that contain “replay” of spatial trajectories at ~20x real-world speeds. Efforts to understand replay typically make multiple assumptions about which events to examine and what sorts of representations constitute replay. We therefore lack a clear understanding of both the prevalence and the range of representational dynamics associated with replay. Here we develop a state space model that uses a combination of movement dynamics of different speeds to capture the spatial content and time evolution of replay during SWRs. Using this model, we find that the large majority of replay events contain spatially coherent, interpretable content. Furthermore, most events progress at real-world, rather than accelerated, movement speeds, consistent with actual experiences.