(WP 2010-02) The Demand for Historic Preservation

Historic preservation is commonly used to protect old buildings and neighborhoods from deterioration. In 1981, the City of Milwaukee established a historic preservation commission to develop and maintain a local register of places with historical importance to the area. The commission also reviews all applications for historic status as well as any requests for exterior alterations. As such, there are numerous rules and restrictions that are imposed on property owners once it has been declared a historic site. Thus, while historic designation can serve to internalize the externalities in neighborhoods with historic buildings, it also imposes costs on homeowners who wish to make improvements to their homes. This paper uses a hedonic model to estimate the impact of historic preservation on the sale price of a single family home in the Milwaukee area. Preliminary results show that the impact of historic preservation is positive when it is significant, with the average impact at 26.6%. However, there was significant variation between districts, with the impact significantly positive in 13 of 22 districts used in the sample. Specifically, the positive impact ranged between 11% and 65%, holding other factors constant. None of the 22 districts had a negative and significant impact. An evaluation of spillover effects reveal that just over one third of them displayed positive and significant spillover effects, whereas 21% had negative and significant spillover effects. The remainder were insignificant. An important question is what factors influence this variability in historic preservation effects. The eventual goal of this research is to extend our preliminary analysis to two stages using a recently developed method that employs spatial econometric methods to solve the unique identification problems inherent in hedonic models (Carruthers and Clark, forthcoming in Journal of Regional Science). This will permit us to determine the specific factors that influence these premiums. While the spatial estimates presented in this preliminary work do not permit a two-stage model, we did explore whether implicit prices appear to be correlated with the household income and racial makeup of the neighborhoods in which they are located. The findings show little evidence that the implicit values of historic districts are correlated, but the implicit price associated with historic district spillovers was positively correlated with both neighborhood measures

Classical models of urban population density. The case of Barcelona Metropolitan Area

In this paper, we study the classical functional forms density-distance and its relation with the suburbanization for the Barcelona Metropolitan Area. The investigation of population concentration will be based on a mesure of the population density gradients derived from the classical models of urban population density. The monocentric urban density analysis has received considerable attention in urban geography and regional science as an empirical issue as well as from a theorical standpoint. The classic study by Colin Clark (1951), followed by the work of Muth (1969) and Mills (1970, 1972), has led to an extensive body of literature dealing with empirical implementations for a wide range of metropolitan areas and cities, in different countries and moments of time. In this work we analize the classical econometric models of urban density. Some of them have been used in studies about the traffic planning and some others in theoretical models on housing market. Quantitative geography has also attempted to model the urban population density. The functions have been estimated from the data sets of Barcelona Metropolitan Area (for six periods of time, 1975-1998) and eleven subcenters whose population ranges from 50.000 to over 200.000 (for one period, 1991). The data are taken from the municipality and census tract area and population data from the Census of Population

Measuring Spatial Dynamics in Metropolitan Areas

This paper introduces a new approach to measuring neighborhood change. Instead of the traditional method of identifying “neighborhoods†a priori and then studying how resident attributes change over time, our approach looks at the neighborhood more intrinsically as a unit that has both a geographic footprint and a socioeconomic composition. Therefore, change is identified when both as- pects of a neighborhood transform from one period to the next. Our approach is based on a spatial clustering algorithm that identifies neighborhoods at two points in time for one city. We also develop indicators of spatial change at both the macro (city) level as well as local (neighborhood) scale. We illustrate these methods in an application to an extensive database of time-consistent census tracts for 359 of the largest metropolitan areas in the US for the period 1990-2000.

Visual feedback alters force control and functional activity in the visuomotor network after stroke.

Modulating visual feedback may be a viable option to improve motor function after stroke, but the neurophysiological basis for this improvement is not clear. Visual gain can be manipulated by increasing or decreasing the spatial amplitude of an error signal. Here, we combined a unilateral visually guided grip force task with functional MRI to understand how changes in the gain of visual feedback alter brain activity in the chronic phase after stroke. Analyses focused on brain activation when force was produced by the most impaired hand of the stroke group as compared to the non-dominant hand of the control group. Our experiment produced three novel results. First, gain-related improvements in force control were associated with an increase in activity in many regions within the visuomotor network in both the stroke and control groups. These regions include the extrastriate visual cortex, inferior parietal lobule, ventral premotor cortex, cerebellum, and supplementary motor area. Second, the stroke group showed gain-related increases in activity in additional regions of lobules VI and VIIb of the ipsilateral cerebellum. Third, relative to the control group, the stroke group showed increased activity in the ipsilateral primary motor cortex, and activity in this region did not vary as a function of visual feedback gain. The visuomotor network, cerebellum, and ipsilateral primary motor cortex have each been targeted in rehabilitation interventions after stroke. Our observations provide new insight into the role these regions play in processing visual gain during a precisely controlled visuomotor task in the chronic phase after stroke

Neuroimaging Evidence of Major Morpho-Anatomical and Functional Abnormalities in the BTBR T+TF/J Mouse Model of Autism

BTBR T+tf/J (BTBR) mice display prominent behavioural deficits analogous to the defining symptoms of autism, a feature that has prompted a widespread use of the model in preclinical autism research. Because neuro-behavioural traits are described with respect to reference populations, multiple investigators have examined and described the behaviour of BTBR mice against that exhibited by C57BL/6J (B6), a mouse line characterised by high sociability and low self-grooming. In an attempt to probe the translational relevance of this comparison for autism research, we used Magnetic Resonance Imaging (MRI) to map in both strain multiple morpho-anatomical and functional neuroimaging readouts that have been extensively used in patient populations. Diffusion tensor tractography confirmed previous reports of callosal agenesis and lack of hippocampal commissure in BTBR mice, and revealed a concomitant rostro-caudal reorganisation of major cortical white matter bundles. Intact inter-hemispheric tracts were found in the anterior commissure, ventro-medial thalamus, and in a strain-specific white matter formation located above the third ventricle. BTBR also exhibited decreased fronto-cortical, occipital and thalamic gray matter volume and widespread reductions in cortical thickness with respect to control B6 mice. Foci of increased gray matter volume and thickness were observed in the medial prefrontal and insular cortex. Mapping of resting-state brain activity using cerebral blood volume weighted fMRI revealed reduced cortico-thalamic function together with foci of increased activity in the hypothalamus and dorsal hippocampus of BTBR mice. Collectively, our results show pronounced functional and structural abnormalities in the brain of BTBR mice with respect to control B6 mice. The large and widespread white and gray matter abnormalities observed do not appear to be representative of the neuroanatomical alterations typically observed in autistic patients. The presence of reduced fronto-cortical metabolism is of potential translational relevance, as this feature recapitulates previously-reported clinical observations