Incorporating Spatial Complexity into Economic Models of Land Markets and Land Use Change

Recent work in regional science, geography, and urban economics has advanced spatial modeling of land markets and land use by incorporating greater spatial complexity, including multiple sources of spatial heterogeneity, multiple spatial scales, and spatial dynamics. Doing so has required a move away from relying solely on analytical models to partial or full reliance on computational methods that can account for these added features of spatial complexity. In the first part of the paper, we review economic models of urban land development that have incorporated greater spatial complexity, focusing on spatial simulation models with spatial endogenous feedbacks and multiple sources of spatial heterogeneity. The second part of the paper presents a spatial simulation model of exurban land development using an auction model to represent household bidding that extends the traditional Capozza and Helsley (1990) model of urban growth to account for spatial dynamics in the form of local land use spillovers and spatially heterogeneous land characteristics.urban growth, urbanization, land development, spatial dynamics, heterogeneity, agent-based models, spatial interactions, Land Economics/Use, Research Methods/ Statistical Methods,

An Agent-Based Model of Exurban Land Development

In contrast to urban areas that are aptly characterized by a large population base and scarce land supply, exurban regions have limited households and plentiful land. This basic difference has far reaching implications for spatial equilibrium in exurban land markets. Rather than bidding their maximum willingness-to-pay and reaching a spatial equilibrium in which households are indifferent to location, as is the central condition of urban economic models, we argue that exurban households will be able to retain some amount of surplus in moving to an exurban location and therefore will choose the location that maximizes this locational surplus. In this paper, we first review the handful of structural spatial models of exurban land development that have been developed. We then develop a structural spatial model of exurban land development that captures these hypothesized features of exurban land markets using an auction model to represent household bidding and adapting the Capooza and Helsley (1990) model to represent landowners’ optimal timing of development. A key innovation of our approach is that, in the absence of full capitalization of land or location differences into land prices, households have preferences for some locations over others and thus it is possible to order household location choices in time and space. This greatly facilitates modeling of land use dynamics by enabling us to model location and land use decisions sequentially in time rather than assuming that all development is instantaneous for given levels of population and income in the region. In addition, the spatial agent-based simulation method that is used to implement the model permits an explicit examination of the implications of exurban land market conditions for the evolution of urban development pattern. Specifically, we ask whether these exurban market conditions explain the emergence and persistence of so-called leapfrog development that is characteristic of exurban regions.Land Economics/Use,

A Dynamic Model of Household Location, Regional Growth and Endogenous Natural Amenities with Cross-Scale Interactions

We develop a coupled model of regional migration and lake ecology to study the influence of ecological-economic interactions and relative time scales on transient and asymptotic dynamics. Cross-scale interactions fundamentally change system dynamics by eliminating steady states that are present in the decoupled economic model and introduce important time dependence. We find that the relative time scales of interacting variables are a key determinant in system dynamics and resilience and that the system's asymptotic behavior cannot be determined without considering the full dynamics of the system. Other time-dependent effects are found to matter, e.g., when households base their perceptions of environmental amenities on past observation, a path dependence is introduced that can lead to oscillations or decline in transient population. Finally, interactions are found to multiply the costs and benefits of policy by inducing a positive feedback between the ecological and economic components that can reinforce or offset the direct effect of the policy. Such effects imply that the economic and ecological costs of getting the policy wrong can be large. Our findings underscore the critical importance of accounting for multiple time scales and time dependence and suggest that models that ignore such complications can be quite misleading. At best, such models will fail to capture the full dynamics of the system and at worst, could provide a misleading characterization of the basic dynamical structure of these systems.Community/Rural/Urban Development, Resource /Energy Economics and Policy,

Divergent Time Scales in a Coupled Ecological-Economic Model of Regional Growth

This paper establishes a coupled human-ecological model where slow-varying migration is interacting with fast-varying nutrient dynamics in lake ecology. The nonlinearity and fast-slow dynamics built in the model can generate regime shifts (that is, shifts between different equilibrium states) and slowly-reversible ecological changes. Because ecological conditions do affect and are affected by uncoordinated individual decisions on migration and land-use, the policy challenge does not only lie in the optimal use of ecological service but also in the provision of the right incentives that regulates individual behavior. The possibility of regime shifts and slowly-reversible changes in this coupled model makes policy analysis more interesting and technically challenging. Within this framework, this paper shows that specification of relative time scale between the fast and slow dynamic processes is crucial for the analysis of the system dynamics with/without policy intervention. The calculated solutions show that specification of relative time scale can significantly change the cost, magnitude and length of active intervention in optimal policy. This paper shows that optimal policy (even when resilience does not enter into optimization problem) will always increase the resilience of the desirable equilibrium in the coupled system. The extent of this improvement in resilience depends crucially on the relative time scale. It also shows that simplifying assumptions on the relative time scale can lead to incorrect predictions for both the short-and long-run dynamics.Environmental Economics and Policy,

The Indian oil sardine

The Indian oil sardine, Sardinella longiceps Val, supports a neritic pelagic fishery contributing 2 to 33 % of the annual marine fish production in India. Though distributed all along the Indian coast the species sustains a commercial fishery of high magnitude along the coasts of Kerala, Karnataka , Goa and southern part oJ Maharashtra. During the last fifty years the annual all India production oscillated between 14.000 t in 1952 to 3 lakh t during 1968. Presently the west coast indicates a declining trend compared to an ascending pattern along the east coasl. The production from east coast surpassed that of the west coast contributing 52% of the all India production of 2.03 lakh t in 1998. The fishery along the west coast is known for its fiuctuating nature. Further, the species indicates a cyclic pattern of abundance. A variety of traditional gears were engaged in exploiting the resource till the introduction of modern and sophisticated gear like the purse seines in the late seventies and the ring seines in the late eighties. In fact oil sardine is one among the few species that have ever remained a subject matter of intensive research. The focus of this compilation is to present a comprehensive picture of the Indian oil sardine, its fishery, biology, stock, future prospects of exploitation and management measures needed for yield optimisation

Studies on chromosomal characteristics of Ctenus indicus (Gravely 1931) (Araneae: Ctenidae)

The karyological information gathered for the Indian spiders taxa thus far were cytologically derived from only few species but none for the representatives belonging to the genus Ctenus. Ctenus indicus (Gravely 1931), an Indian ctenid spider was cytogenetically analyzed following conventional, C- and NOR-banding techniques so as to gather substantial data for future course of understanding of karyotypic evolution among spider species. The karyotypic data for Ctenus indicus revealed the complement consisting of (2n = 28) 26AA + X1X2� and (2n = 30) 26AA + X1X1X2X2� acrocentric chromosomes. A closer scrutiny of meiotic progression disclosed many male pachytenic cells displaying the occurrence of �bouquet� formation. The results of C-banding enabled in identifying centromeric constitutive heterochromatin locales, and in some chromosomes also the distal ends of telomeric regions. Silver nitrate stained NOR-specifications were noticed at the distal telomeric regions of two pairs of chromosomes (#8 and #10) in the complement. Cytological evidence procured from the present study not only adds to the ever-growing list of the spider cytogenetic assessments but also offers as a baseline data towards establishing evolutionary relationships within this important group. © 2016, Archana Sharma Foundation of Calcutta

Optogenetic Interrogation of Functional Synapse Formation by Corticospinal Tract Axons in the Injured Spinal Cord

To restore function after injury to the CNS, axons must be stimulated to extend into denervated territory and, critically, must form functional synapses with appropriate targets. We showed previously that forced overexpression of the transcription factor Sox11 increases axon growth by corticospinal tract (CST) neurons after spinal injury. However, behavioral outcomes were not improved, raising the question of whether the newly sprouted axons are able to form functional synapses. Here we developed an optogenetic strategy, paired with single-unit extracellular recordings, to assess the ability of Sox11-stimulated CST axons to functionally integrate in the circuitry of the cervical spinal cord. Initial time course experiments established the expression and function of virally expressed Channelrhodopsin (ChR2) in CST cell bodies and in axon terminals in cervical spinal cord. Pyramidotomies were performed in adult mice to deprive the left side of the spinal cord of CST input, and the right CST was treated with adeno-associated virus (AAV)–Sox11 or AAV–EBFP control, along with AAV–ChR2. As expected, Sox11 treatment caused robust midline crossing of CST axons into previously denervated left spinal cord. Clear postsynaptic responses resulted from optogenetic activation of CST terminals, demonstrating the ability of Sox11-stimulated axons to form functional synapses. Mapping of the distribution of CST-evoked spinal activity revealed overall similarity between intact and newly innervated spinal tissue. These data demonstrate the formation of functional synapses by Sox11-stimulated CST axons without significant behavioral benefit, suggesting that new synapses may be mistargeted or otherwise impaired in the ability to coordinate functional output. SIGNIFICANCE STATEMENT As continued progress is made in promoting the regeneration of CNS axons, questions of synaptic integration are increasingly prominent. Demonstrating direct synaptic integration by regenerated axons and distinguishing its function from indirect relay circuits and target field plasticity have presented technical challenges. Here we force the overexpression of Sox11 to stimulate the growth of corticospinal tract axons in the cervical spinal cord and then use specific optogenetic activation to assess their ability to directly drive postsynaptic activity in spinal cord neurons. By confirming successful synaptic integration, these data illustrate a novel optogenetic-based strategy to monitor and optimize functional reconnection by newly sprouted axons in the injured CNS

Status and scope of research on pelagic fisheries of India

Extensive and indiscriminate exploitation of marine natural resources, during the last three decades is leading to a situation where no more commercial fish stocks may be left in the sea by year 2050 unless ecosystems are protected and the biodiversity is revived, warns a new study cataloging the global collapse of marine ecosystems (Worm et al., 2006). The task of understanding the dynamics of large marine ecosystems to offer effective and relevant scientific advice to develop management interventions is a difficult, complex, expensive and lengthy process. This is especially true in the Indian context where the country has an EEZ of 2.02 million km2, which contributes nearly 40% of the total fish production from the Indian Ocean. Fishes have been mentioned in the ancient literature of India including the epics such as Ramayana and Mahabaratha. Excavations from Mohenjodaro and Harappa indicate that fishing with hooks and nets was common as back as 3000 B.C. and over the years fishing and fisheries in India have evolved at a rapid pace (Ayyappan et al., 2004). Marine fisheries is basically harnessing a natural resource and therefore its management must anchor on knowledge- based interventions generated through close monitoring of their distribution, abundance, exploitation, population dynamics and fluctuations of fish stocks in relation to natural factors and anthropogenic interventions. Against a scenario of an ever-increasing population and stagnant marine fish production in recent years, per capita seafood availability is a serious concern. The countr

Fishery and biology of yellowfin tuna occurring in the coastal fishery in Indian seas

In the recently convened Workshop on "Stock assessment of yellowfin tuna in the Indian Ocean" (FAO/IPTP, 1991) the present status of the fishery, biology and stock structure of yellawfiil tuna taken by different countries bordering the Indian Ocean have been discussed, and recommednations on the development of the fishery for this species made

Drift gill net fishery for large pelagics at Cochin - A case study on by-catch of pelagic sharks

In India, the elasmobranchs contributed on an average 60,8(X) t during 1986 to 1999 forming 2.7% of the total marine fish landings. The production varied from 50,000t in 1990 to a highest of 75,(X)0 t in 1998. The sharks dominated forming 62.4%, followed by rays (33.5%) and skates the rest. The west coast accounted for 55.5% and east coast 44.5%. The highest contribution of 30.2% was from Gujarat followed by Tamilnadu (26.2%). The drift gillnets, sharing 48.5% of the production, was the major gear, followed by trawls (31.5%) and hooks and line (6.1%). Since the drift gillnets (DGN), apart from the scombroids, exploit a variety of larger pelagics, a case study of the shark fishery by the gear at Kochi was made based on the data from 1979 to 1999 and the results are presented her