Toward a comprehensive account of orientation selectivity in the retina.

Retinal Ganglion Cells (RGCs) form functionally distinct signaling channels that selectively encode features of the visual input including direction of motion, contrast polarity, size, and color. A highly conserved visual channel amongst vertebrates conveys orientation selectivity, i.e., the selective firing of neuronal cells in response to elongated stimuli along a preferred orientation. Orientation selectivity is an apparent critical computation and several studies have reported aspects of it, including cell type identity in anatomical reconstructions, and functional characterization of at least four different identified RGC types. But how cell types in the different studies relate is not well resolved; the mechanisms that generate the orientation selective responses in mice remain incompletely understood; and the retinofugal projections of OS RGC types are unknown. The goal of this study was to comprehensively characterize Orientation Selective (OS) RGC types in the mouse retina, and to elucidate the mechanisms that contribute to their tuning properties. We used population calcium imaging and hierarchical clustering to identify orientation selective RCGs in retinal explants. We then targeted these cells for detailed morphological and electrophysiological study. Our survey of RGC populations and subsequent morphological analysis distinguished 10 morphological types with apparent OS tuning. Electrophysiological analysis of 5 types identified specific tuning mechanisms, including a type with tuned excitation and inhibition, and a type with just tuned inhibition. Retrograde tracing from dLGN indicates that OS cells project to the shell region of the dorsal Lateral Geniculate Nucleus (dLGN), indicating that at least some OS RGC types contribute to dLGN OS tuning. This work provides new insight into the morphology and function of RGC types that exhibit OS properties. Additional studies will be necessary to further solidify the full complement of OS types in the retina and resolve their detailed circuit-level mechanisms, synaptic partners, molecular profiles, and retinofugal projections

An Agent-based Collective Model to Simulate Peer Pressure Effect on Energy Consumption

This paper presents a novel model for simulating peer pressure effect on energy awareness and consumption of families. The model is built on two well-established theories of human behaviour to obtain realistic peer effect: the collective behaviour theory and the theory of cognitive dissonance. These theories are implemented in a collective agentbased model that produces fine-grained behaviour and consumption data based on social parameters. The model enables the application of different energy efficiency interventions which aim to obtain more aware occupants and achieve more energy saving. The presented experiments show that the implemented model reflects the human behaviour theories. They also provide examples of how the model can be used as an analytical tool to interpret the effect of energy interventions in the given social parameters and decide the optimal intervention needed in different cases

Urban Biodiversity and Landscape Ecology: Patterns, Processes and Planning

Effective planning for biodiversity in cities and towns is increasingly important as urban areas and their human populations grow, both to achieve conservation goals and because ecological communities support services on which humans depend. Landscape ecology provides important frameworks for understanding and conserving urban biodiversity both within cities and considering whole cities in their regional context, and has played an important role in the development of a substantial and expanding body of knowledge about urban landscapes and communities. Characteristics of the whole city including size, overall amount of green space, age and regional context are important considerations for understanding and planning for biotic assemblages at the scale of entire cities, but have received relatively little research attention. Studies of biodiversity within cities are more abundant and show that longstanding principles regarding how patch size, configuration and composition influence biodiversity apply to urban areas as they do in other habitats. However, the fine spatial scales at which urban areas are fragmented and the altered temporal dynamics compared to non-urban areas indicate a need to apply hierarchical multi-scalar landscape ecology models to urban environments. Transferring results from landscape-scale urban biodiversity research into planning remains challenging, not least because of the requirements for urban green space to provide multiple functions. An increasing array of tools is available to meet this challenge and increasingly requires ecologists to work with planners to address biodiversity challenges. Biodiversity conservation and enhancement is just one strand in urban planning, but is increasingly important in a rapidly urbanising world

Characterization of Masticated Fuelbeds and Fuel Treatment Effectiveness in Southeastern US Pine Ecosystems.

Mechanical fuels treatments are being widely used in fire prone ecosystems where fuel loading poses a hazard, yet little research examining fuel dynamics, fire behavior, and ecological effects exists, especially in the southeastern US. In order to broaden our understanding of these treatments, effects of mechanical mastication ( mowing ) were examined in a common pine ecosystem of the southeastern US Coastal Plain, where the post-mastication fuel environment is unique among ecosystems where mastication is being employed. Foliar litter dominates surface fuels after understory mastication in palmetto/gallberry pine flatwoods, however rapid recovery of shrubs quickly regains control over fire behavior. Treatments were effective at reducing flame heights during post-treatment prescribed burning in these sites, however compact surface fuels were observed to cause long-duration heating during laboratory burning. Overstory tree mortality observed following summer burning in mowed treatments may have resulted from combustion of the compact surface fuels beneath the shrub layer. Although temperature and humidity at the shrub level were minimally impacted, drier surface fuels existed in masticated sites where shrub cover was reduced, potentially exacerbating combustibility of the surface fuel layer. Treatments had little impact on understory vegetation communities or soil nutrients, however, observed reduction in saw palmetto may alter future groundcover, as slight increases in grass cover were observed. The fast recovery of understory vegetation and generally low impact to ecosystem attributes suggest resiliency of these pine flatwoods following mechanical treatments. However, their effectiveness at reducing fire hazard is likely short-lived. Treatment regimes that utilize prescribed burning to reduce post-mastication fuels will require special attention to treatment timing in order to ensure surface litter consumption, while minimizing potential impacts to the overstory

Cycles of Demand and Distribution and Monetary Policy in the US Economy

The role of monetary policy on the cyclical behavior of the labor share and capacity utilization in the US economy is studied empirically. Previous estimation results remain robust; the inclusion of the rate of interest does not alter the underlying specification of the distributive demand regime. Next, the role of monetary policy on net borrowing flows for four institutional sectors are analyzed. Interest rate effects appear most important for households. Based on this finding, implications for countercyclical stabilization policy are spelled out. (author's abstract