Spatial Contraction Research Articles

Territorial Structure and Organization of Agriculture in Tyumen Oblast in 1973 and 2014: Comparative Analysis

The reduction in agricultural areas is a vivid manifestation of the spatial contraction of post-Soviet Russia’s socio-geographical space. Based on a case study of Tyumen oblast, the author examines the changes in the territorial structure of agriculture. He compares agricultural indicators in two time slices: 1973 and 2014. The sources for the work were the 1976 Atlas of Tyumen Oblast, Rosstat statistical materials, and also freely accessible Rosstat data on the accounting statements of enterprises. The results of the study showed that individual elements of the spatial structure of agrarian industry established in the Soviet period have been preserved and reproduced in modern conditions. The transition to the market led to the spatial contraction of agrarian production; however, the structure of sown areas remains close to the early 1960s model, where in terms of farm distribution, the prior cores and confinedness to large landscape and transport axes remain. Major shifts have been revealed in how the contribution of individual territories to gross regional product is distributed. The main revenue in the region’s agricultural sector is concentrated with a small number of agroindustrial enterprises located close to the regional capital. This indicates (1) an increased dependence of the location of production on the accessibility to a large city as a source of qualified personnel and a market outlet, and (2) an altered model of organizing production, towards its greater centralization and strict specialization, as well as a functional distinction between head (processing) and subsidiary (raw materials) companies united in a closed production chain.

1980s–2010s: The world's largest mangrove ecosystem is becoming homogeneous

Knowledge gaps in spatiotemporal changes in mangrove diversity and composition have obstructed mangrove conservation programs across the tropics, but particularly in the Sundarbans (10,017 km2), the world's largest remaining natural mangrove ecosystem. Using mangrove tree data collected from Earth's largest permanent sample plot network at four historical time points (1986, 1994, 1999 and 2014), this study establishes spatially explicit baseline biodiversity information for the Sundarbans. We determined the spatial and temporal differences in alpha, beta, and gamma diversity in three ecological zones (hypo-, meso-, and hypersaline) and also uncovered changes in the mangroves' overall geographic range and abundances therein. Spatially, the hyposaline mangrove communities were the most diverse and heterogeneous in species composition while the hypersaline communities were the least diverse and most homogeneous at all historical time points. Since 1986, we detect an increasing trend of compositional homogeneity (between-site similarity in species composition) and a significant spatial contraction of distinct and diverse areas over the entire ecosystem. Temporally, the western and southern hypersaline communities have undergone radical shifts in species composition due to population increase and range expansion of the native invasive species Ceriops decandra and local extinction or range contraction of specialists including the globally endangered Heritiera fomes. The surviving biodiversity hotspots are distributed outside the legislated protected area network. In addition to suggesting the immediate coverage of these hotspots under protected area management, our novel biodiversity insights and spatial maps can form the basis for spatial conservation planning, biodiversity monitoring and protection initiatives for the Sundarbans.

Spatial contraction of demersal fish populations in a large marine ecosystem

AbstractAimThe interdependencies between trophic interactions, environmental factors and anthropogenic forcing determine how species distributions change over time. Large changes in species distributions have occurred as a result of climate change. The objective of this study was to analyse how the spatial distribution of cod and flounder has changed in the Baltic Sea during the past four decades characterized by large hydrological changes.LocationBaltic SeaTaxonCod (Gadus morhua) and flounder (Platichthys flesus).MethodsCatch per unit of effort (CPUE) data for adult and juvenile cod and for adult flounder were modelled using Delta‐Generalized additive models including environmental and geographical variables between 1979 and 2016. From the annual CPUE predictions for each species, yearly distribution maps and depth distribution curves were obtained. Mean depth and the depth range were estimated to provide an indication on preferred depth and habitat occupancy.ResultsAdult and juvenile cod showed a contraction in their distribution in the southern areas of the Baltic Sea. Flounder, instead, showed an expansion in its distribution with an increase in abundance in the northern areas. The depth distributions showed a progressive shift of the mean depth of occurrence towards shallower waters for adult cod and flounder and towards deeper waters for juvenile cod, as well as a contraction of the species depth ranges, evident mainly from the late 1980s.Main conclusionsOur study illustrates large changes in the spatial distribution of cod and flounder in the Baltic Sea. The changes in depth distribution occurred from the late 1980s are probably due to a combination of expanded areas of hypoxia in deep waters and an increase in predation risk in shallow waters. The net effect of these changes is an increased spatial overlap between life stages and species, which may amplify cod cannibalism and the interaction strength between cod and flounder.

Experiencing regularisation in Accra, Cape Town and Rio de Janeiro

In the prolific contemporary discussions on the right to the city, little attention has been paid to the multifaceted political meaning of the reshaping of city dwellers’ rights, duties and responsibilities through regularisation processes inspired by neoliberal logics. This paper fills in this gap by engaging in an analysis of the dialectical relation between the political dimension of everyday life, urban rights, neoliberal urban policies and political emancipation. We thereby break from a radical reading of Lefebvre’s notion and from a focus on political mobilisation in order to cast a new light on the debate on the right to the city. Three regularisation policies, all linked to the affirmation of a commercial or fiscal relationship to the state are considered through a cross-case analysis: the regularisation that followed the forced displacement of street traders in central Accra; an in situ process of regularisation of street trading in a Cape Town central market; the regularisation of electricity services in the favelas of Rio de Janeiro, a policy that seeks to re-establish a commercial relationship with favela residents by redefining their rights and responsibilities as registered customers of a private electricity provider. We resort to an exploratory notion, the actual right to the city, to examine how these forms of administrative regularisation have reshaped urban life. We argue that these processes of regularisation convey de-politicisation dynamics, such as the fragmentation and individualisation of political identities, along with the possible re-politicisation of certain stakes, such as the strengthening of individual and collective political expectations toward the State. This tension is due to the ambiguous nature of the new social and spatial contract between State and citizens emerging from regularisation. Beyond the necessary analysis of political struggles against neoliberal policies, and the essential assessment of their impact on urban inequalities, we therefore call for a better consideration of the ambiguous and less visible political impact of processes of selective inclusion and recognition by the State on the way city dwellers envision their rights and duties.

Edge, common space and the spatial contract: A three-way conversation with Ed Casey, Stavros Stavrides and Antonis Vradis

Edge, common space and the spatial contract: A three-way conversation with Ed Casey, Stavros Stavrides and Antonis Vradis

Traffic dynamics of carnival processions

The traffic dynamics of processions are described in this study. GPS data from participating groups in the Cologne Rose Monday processions 2014–2017 are used to analyze the kinematic characteristics. The preparation of the measured data requires an adjustment by a specially adapted algorithm for the map matching method. A higher average velocity is observed for the last participant, the Carnival Prince, than for the leading participant of the parade. Based on the results of the data analysis, for the first time a model can be established for defilading parade groups as a modified Nagel-Schreckenberg model. This model can reproduce the observed characteristics in simulations. They can be explained partly by the constantly moving vehicle driving ahead of the parade leaving the pathway and partly due to a spatial contraction of the parade during the procession.

Changes and drivers of freshwater mussel diversity and distribution in northern Borneo

Human activities are threatening Borneo's unique biodiversity, but little is known on the status of freshwater invertebrates. We assessed changes in diversity and distribution of freshwater mussels (Bivalvia: Unionida) in northern Borneo, and identified drivers of present distribution and threats. Past distribution data were collected from literature and museum resources. Present distribution data were collected from 21 river basins, and 47 water quality, climatic, landscape and human variables explored as potential predictors of species presence/absence. Species delimitations were identified by morphology and COI barcoding, and haplotype networks generated. Our data indicate that over the past 50 years, four of originally five native species have become very rare or possibly locally extirpated. Since these four species are endemic to Borneo, other Bornean river basins should urgently be surveyed to identify any remaining populations. In the same time span, the non-native Sinanodonta woodiana has become the most widespread freshwater mussel in northern Borneo. The fifth native species was identified as Rectidens sumatrensis and found in four Sarawakian river basins, thus contradicting previous assumptions of an endemic Bornean Rectidens species. Although a number of stable R. sumatrensis populations are retained across Sarawak, the species' strong spatial contraction in mainland Sundaland and apparent low tolerance to eutrophication suggest that it is vulnerable to further habitat alteration. Our results indicate that Borneo's (endemic) freshwater invertebrate biodiversity is declining rapidly. Comprehensive surveys targeting an array of invertebrate and vertebrate taxa are needed to identify Borneo's freshwater biodiversity hotspots, where conservation efforts should be concentrated.

On the consistency of the Oppenheimer-Snyder solution for a dust star. Reply to Marshall’s criticism

The recent alternative to the Oppenheimer-Snyder (OS) solution for a dust star proposed by Marshall in the paper “Gravitational collapse without black holes” (Astrophys. Space Sci. 342:329, 2012) is analyzed. It is shown that this proposal leads to a non-diagonal metric, with which the Einstein equations become practically unsolvable. Any ansatz proposed as their exact solution turns out to be arbitrary and may be unlimited number of the such solutions. This is due to the fact that an auxiliary function $y(R,r)$ , introduced by OS as $t=M(y)$ , is unambiguously fixed by the diagonality condition and the matching on the surface, and thus in the non-diagonal case it remains arbitrary. It is also shown that the OS solution, as a description in terms of the Schwarzschild coordinates, leads to a frozen star (or frozar) picture not only for the surface, asymptotically freezing outside the gravitational radius, but for interior layers too which also freeze near their own asymptotes. At most of the inner region these asymptotes are located almost equidistantly and only for layers initially close to the surface they become denser. The reason for the such densifying is not “a gravitational repulsion”, but their later freezing and higher spatial contractions, while they remain be uniform and free falling in the comoving frames.

Woody plant encroachment following grazing abandonment in the subalpine belt: a case study in northern Spain

The montane and subalpine belts in European mountains were affected by intense land use/land cover changes during the twentieth century. In the case of the subalpine belt, most European mountains were affected by complex deforestation processes from Neolithic times, leading to the expansion of summer grasslands to support grazing by transhumant sheep and goats flocks. This resulted in an altitudinal reduction of the tree line and the occurrence of severe soil erosion and shallow landsliding. The intense livestock pressure over centuries explains why the landscape remained without major change until the middle of the twentieth century. Since then, depopulation, land abandonment, and the disappearance of the transhumant system have resulted in a marked decline in livestock numbers and subsequent encroachment of shrubs and trees in the subalpine belt. The Urbion Mountains (Iberian Range, northern Spain) provides one of the clearest examples in the Iberian Peninsula, where there was intense deforestation since the Neolithic period to enlarge the area of subalpine summer grasslands. The recent reversal of this situation in the last decades led to (i) a marked trend to dense forest, which resulted in an average 200 m altitudinal advance, and (ii) the spatial contraction of shrublands, which have been replaced by dense forest in the highest areas. Changes will continue in the future, possibly enhanced by global warming.

A conjecture concerning determinism, reduction, and measurement in quantum mechanics

It is shown that it is possible to introduce determinism into quantum mechanics by tracing the probabilities in the Born rules back to pseudorandomness in the absolute phase constants of the wave functions. Each wave function is conceived to contain an individual phase factor exp(iα). In an ensemble of systems the phase constants α are taken to be pseudorandom numbers. A reduction process (collapse), independent of any measurement, is conceived to be a spatial contraction of two wavepackets when they meet and satisfy a certain criterion. The criterion depends on the phase constants of both wavepackets. The measurement apparatus fans out the incoming wavepacket into spatially separated eigenpackets of the observable and a reduction associates the point of contraction with an eigenvalue of the observable. The theory is nonlocal and contextual.

On the Dynamics of the Formation of the Kelvin Cat’s-Eye in Tropical Cyclogenesis. Part II: Numerical Simulation

Abstract A shallow-water model is used to study the role of critical layers in tropical cyclogenesis. Forced and unforced problems of disturbances on a parabolic jet associated with weak basic-state meridional potential vorticity (PV) gradients, leading to Kelvin cat’s-eye formation around the jet axis, are first investigated. Numerical simulations with various initial disturbance magnitudes and structures suggest that the results of previous studies can be extended to the next level of complexity toward the more realistic atmosphere. The model is therefore initialized using an observed jet profile obtained from the reanalysis data presented in Part I of this study. For this asymmetric marginally stable basic-state profile, unforced (free) and forced linear integrations show spatial contraction of the perturbation structures in the meridional direction, similar to what occurred in experiments on the parabolic jet. Nonlinear free simulations highlight the role of nonlinear processes in redistributing PV within the critical-layer region. However, they do not yield a realistic time scale for the formation of the cat’s-eye. By including diabatic heating as a mass sink term to represent convective PV generation, the nonlinear forced simulation is found to produce a realistic time scale for cat’s-eye formation, and confirms the analytical solution of τeτQ ~ O(ε−1) obtained in Part I. These results highlight the synergic role of the dynamical mechanisms, including wave breaking and PV redistribution within the nonlinear critical layer characterized by weak PV gradients and the thermodynamical mechanisms such as convectively generated PV anomalies in the cat’s-eye formation in tropical cyclogenesis.

Pearl mussels (Margaritifera marocana) in Morocco: Conservation status of the rarest bivalve in African fresh waters

Margaritifera marocana is one of the rarest freshwater mussel species (listed as critically endangered), and is endemic to Morocco. Despite its constrained distribution and low abundance, to date there are no quantitative studies addressing the conservation status of this species. Surveys were conducted in 36 sites along the Oum Er Rbia river basin (Rivers Derna, Laabid and Oum Er Rbia) to assess the distribution, abundance, population structure and genetic diversity of M. marocana. Just one specimen was found on River Oum Er Rbia and none on River Derna; however, a high abundance was found in the lower section of River Laabid (e.g., site Laabid 6 reached a mean density of 11.0±6.8ind.m−2). Contrary to earlier information, which reported an overall population size fewer than 250 individuals in a restricted area and no juvenile presence, this study showed that a much higher abundance exists in River Laabid alone. In addition, the species is present in more than 50km of this river and is still recruiting since small specimens were found. Regarding genetic diversity, six of nine loci previously used in Margaritifera margaritifera were polymorphic and suitable in M. marocana. The spatial range contraction of this species is likely to be very recent, since no strong signature was detected by the molecular diversity indices. Information gathered in this study can be used as a reference to the present conservation status of M. marocana, and guide future research and management initiatives to better conserve it. We conclude discussing the potential major threats for the future survival of M. marocana and suggest some management measures (and research needs) that should be urgently applied.

Recovery of a Surf Clam Donax deltoides Population in Southern Australia: Successful Outcomes of Fishery‐Independent Surveys

AbstractEstimates of biomass or relative biomass are required for monitoring the recovery of depleted bivalve resources and for the management of newly exploited resources. Uncertainty around fishery catch per unit effort (CPUE) as a proxy for biomass highlights the need for fishery‐independent assessments. Following a prolonged period of decline in Australia's largest fishery for surf clam Donax deltoides, robust estimates of biomass were required to monitor recovery and to set appropriate total allowable commercial catches. Estimates of relative biomass were derived from fishery‐independent surveys (FIS) conducted cooperatively by researchers and fishers. The FIS assessed both the spatial (m to km) and temporal (months to years) dynamics of the fishery and enabled comparisons with CPUE. Concurrent size‐frequency distributions provided information on the mechanisms underlying variability in resource status across the fishery. Increasing relative biomass and complexity of size structures indicated recovery of the resource from 2009, although spatial contraction of the resource also occurred. Relative biomass from FIS provides a robust fishery performance indicator that is appropriate to the scale of the fishery and has advantages over fishery‐dependent CPUE of finer temporal and spatial resolution and consistent sampling efficiency. Performance indicators based on FIS provide improved understanding of the changes in resource status. Active engagement of fishers contributes to enhanced economic and environmental outcomes.Received December 9, 2014; accepted September 3, 2015

Implications of spatial contraction for density dependence and conservation in a depressed population of anadromous fish

Changes in density-independent mortality can alter the spatial extent of populations through patch extinction and colonization, and spatial contraction may alter population productivity and compensatory capacity. Here, we analyze a time series of steelhead (Oncorhynchus mykiss) abundance and examine the hypothesis that spatial contraction can decrease compensatory capacity. Over the last 20 years, steelhead in the Keogh River have declined by an order of magnitude because of a period of poor smolt-to-adult survival. Low abundance has been associated with more depressed production of out-migrating smolts than would be expected based on traditional models of compensatory dynamics. Patterns of juvenile density over time show changes in the spatial distribution of the population. We developed a spatially explicit population model to explore spatial structure and juvenile recruitment under varying marine survival. Results suggest that spatial contraction during a period of poor marine survival can strengthen density-dependent population regulation, reducing smolt production at the watershed scale. Our results highlight that spatial contraction can alter the fundamental density-dependent relationships that define population dynamics, recovery trajectories, and sustainable harvest levels of spatially structured populations.

Obtaining General Relativity's N‐body non‐linear Lagrangian from iterative, linear algebraic scaling equations

AbstractA local system of bodies in General Relativity whose exterior metric field asymptotically approaches the Minkowski metric effaces any effects of the matter distribution exterior to its Minkowski boundary condition. To enforce to all orders this property of gravity which appears to hold in nature, a method using linear algebraic scaling equations is developed which generates by an iterative process an N‐body Lagrangian expansion for gravity's motion‐independent potentials which fulfills exterior effacement along with needed metric potential expansions. Then additional properties of gravity – interior effacement and Lorentz time dilation and spatial contraction – produce additional iterative, linear algebraic equations for obtaining the full non‐linear and motion‐dependent N‐body gravity Lagrangian potentials as well. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

On nonlinear Schrödinger equations derived from the nonrelativistic limit of nonlinear Klein–Gordon equations in de Sitter spacetime

Some Schrödinger equations with weighted nonlinear terms are derived from the nonrelativistic limit of nonlinear Klein–Gordon equations in de Sitter spacetime. Local and global solutions for the Cauchy problem are considered in Sobolev spaces for power type and exponential type nonlinear terms. The roles of spatial expansion and contraction on the problem are studied. And a dissipative property of the equations is remarked.

Can General Relativity’s N-body Lagrangian be obtained from iterative algebraic scaling equations? II. Interior effacement and time dilation

In the companion paper [1], iterative algebraic scaling equations were developed which yield motion-independent potentials to all non-linear orders for gravity’s N-body Lagrangian which enforce exterior effacement—that local gravity expressed in local proper coordinates is not affected by the distribution of matter in the universe exterior and far from the local system of bodies. This paper deals with determination of the motion-dependent potentials of gravity’s N-body Lagrangian. Additional algebraic scaling conditions are developed for this purpose which exploit other invariances desired for gravity—that a local gravitational system must have dynamics which manifest Lorentz time dilation and spatial contractions upon boosts and does not reveal a preferred inertial frame in the cosmos; and additionally, for composite body sources, interior effacement is enforced in which only a single total mass-energy parameter represents the body in its spherical limit in all N-body Lagrangian potentials. Iterative algebraic equations for enforcing these conditions as well as the exterior effacement condition are applied to obtain a 1/c 4 order N-body Lagrangian for gravity.

Can General Relativity’s N-body Lagrangian be obtained from iterative algebraic scaling equations? I. Exterior effacement

A local system of bodies in General Relativity whose exterior metric field asymptotically approaches the Minkowski metric effaces any effects of the matter distribution exterior to the Minkowski boundary condition. To enforce to all orders this property of gravity which appears to hold in nature, a method using linear algebraic scaling equations is developed, which generates by an iterative process an Nbody Lagrangian expansion for gravity’s motion-independent potentials, which fulfills the exterior effacement. The algebraic method is then applied in this first of two papers to produce the motion-independent N-body gravity Lagrangian to the 1/c4 order of expansion. A subsequent paper supplements exterior effacement conditions with others—interior effacement and Lorentz time dilation and spatial contraction—to create additional iterative algebraic equations for obtaining the nonlinear, motion-dependent N-body gravity Lagrangian potentials as well. The scaling conditions developed in these papers may also serve as validation checks on more traditional determinations of higher-order gravity which employ perturbative solutions of gravity’s nonlinear field equations.

CT imaging during microwave ablation: analysis of spatial and temporal tissue contraction.

To analyze the spatial distribution and temporal development of liver tissue contraction during high-temperature ablation by using intraprocedural computed tomography (CT) imaging. A total of 46 aluminum fiducial markers were positioned in a 60 × 45 mm grid, in a single plane, around a microwave ablation antenna in each of six ex vivo bovine liver samples. Ablations were performed for 10 min at 100 W. CT data of the liver sample were acquired every 30 s during ablation. Fiducial motion between acquisitions was tracked in postprocessing and used to calculate measures of tissue contraction and contraction rates. The spatial distribution and temporal evolution of contraction were analyzed. Fiducial displacement indicated that the zone measured postablation was 8.2 ± 1.8 mm (∼20%) smaller in the radial direction and 7.1 ± 1.0 mm (∼10%) shorter in the longitudinal direction than the preablation tissue dimension. Therefore, the total ablation volume was reduced from its preablation value by approximately 45%. Very little longitudinal contraction was noted in the distal portion of the ablation zone. Central tissues contracted more than 60%, which was near an estimated limit of ∼70% based on initial water content. More peripheral tissues contracted only 15% in any direction. Contraction rates peaked during the first 60 s of heating with a roughly exponential decay over time. Ablation zones measured posttreatment are significantly smaller than the pretreatment tissue dimensions. Tissue contraction is spatially dependent, with the greatest effect occurring in the central ablation zone. Contraction rate peaks early and decays over time.

Biophysical transport model suggests climate variability determines distribution of Walleye Pollock early life stages in the eastern Bering Sea through effects on spawning

The eastern Bering Sea recently experienced an anomalously warm period followed by an anomalously cold period. These periods varied with respect to sea ice extent, water temperature, wind patterns, and ocean circulation. The distributions of Walleye Pollock early life stages also differed between periods, with larval stages found further eastward on the shelf in warm years. Statistical analyses indicated that these spatial distributions were more closely related to temperature than to other covariates, though a mechanism has not been identified. The objective of this study was to determine if variable transport could be driving the observed differences in pollock distributions. An individual-based model of pollock early life stages was developed by coupling a hydrodynamic model to a particle-tracking model with biology and behavior. Simulation experiments were performed with the model to investigate the effects of wind on transport, ice presence on time of spawning, and water temperature on location of spawning. This modeling approach benefited from the ability to individually test mechanisms to quantitatively assess the impact of each on the distribution of pollock. Neither interannual variability in advection nor advances or delays in spawning time could adequately represent the observed differences in distribution between warm and cold years. Changes to spawning areas, particularly spatial contractions of spawning areas in cold years, resulted in modeled distributions that were most similar to observations. The location of spawning pollock in reference to cross-shelf circulation patterns is important in determining the distribution of eggs and larvae, warranting further study on the relationship between spawning adults and the physical environment. The different distributions of pollock early life stages between warm and cold years may ultimately affect recruitment by influencing the spatial overlap of pollock juveniles with prey and predators.