Energy upper bound for structurally-stable N-passive states

Passive states are special configurations of a quantum system which exhibit no energy decrement at the end of an arbitrary cyclic driving of the model Hamiltonian. When applied to an increasing number of copies of the initial density matrix, the requirement of passivity induces a hierarchical ordering which, in the asymptotic limit of infinitely many elements, pinpoints ground states and thermal Gibbs states. In particular, for large values of N the energy content of a N-passive state which is also structurally stable (i.e. capable to maintain its passivity status under small perturbations of the model Hamiltonian), is expected to be close to the corresponding value of the thermal Gibbs state which has the same entropy. In the present paper we provide a quantitative assessment of this fact, by producing an upper bound for the energy of an arbitrary N-passive, structurally stable state which only depends on the spectral properties of the Hamiltonian of the system. We also show the condition under which our inequality can be saturated. A generalization of the bound is finally presented that, for sufficiently large N, applies to states which are N-passive, but not necessarily structurally stable

Seeking the Optimal Dimension of Local Administrative Units: A Reflection on Urban Concentration and Changes in Municipal Size

In the search for a better administrative functioning as a key dimension of economic performances, changes in municipal boundaries and the creation (or suppression) of local administrative units reflect a progressive adjustment to a spatially varying population size and density. With intense population growth, municipal size reflects the overall amount (and spatial concentration) of services and infrastructures, being functionally related with agglomeration economies, land availability for building, and specific sociodemographic attributes of local communities. Based on these premises, the intrinsic relationship between settlement expansion, population growth, and municipal size in a metropolitan region of Southern Europe (Attica, hosting the Greater Athens’ area in Central Greece) was investigated in this study over nearly one century as a contribution to a refined investigation of the (changing) organization of local administrative units under a complete metropolitan cycle from urbanization to reurbanization. Based on descriptive statistics, mapping, (parametric and nonparametric) correlation coefficients, and econometric techniques, a quantitative analysis of the relationship between population size and density and municipal area provides pivotal knowledge to policy and planning adjustments toward a more balanced spatial distribution of population and administered land among local government units. Together with a slight decrease in the average municipal size over time, the average population density per municipal unit increased systematically, with a considerable reduction in spatial heterogeneity of settlements. The observed goodness-of-fit of the linear model explaining municipal area with population density, increased significantly over time. Empirical results of our study indicate that municipal size has slowly adjusted to population density across metropolitan areas, determining an imbalanced spatial distribution of resident population and a supposedly less efficient government partition. The recent administrative reform of local authorities in Greece (the so-called ‘Kallikratis’ law) seems to consolidate–rather than rebalance this organizational structure over space, reflecting spatially polarized settlements. Such conditions represent a base for informed analysis of the spatial structure of local administrative units as a pivotal element of economic sustainability and may contribute to the debate on the optimal size of municipalities at both urban and metropolitan scales of governance

Agro-forest management and soil degradation in Mediterranean environments. Towards a strategy for sustainable land use in vineyard and Olive Cropland

Landscape fragmentation typical of the Mediterranean region is the result of long-term settlement history and continuous socioeconomic interactions among countries. In complex agro-ecosystems of the Mediterranean basin, formulation of practical guidelines aimed at counteract soil and land degradation, water depletion, rural area depopulation, and the loss of agricultural knowledge is imperative. Based on a multidisciplinary, integrated approach, the present contribution discusses the role of traditional agricultural systems in ecosystem services provision, considering together economic sustainability and the medium-term ecological benefits. A permanent monitoring of rural areas specialized in traditional crop production such as olive and vine may support optimal selection of cultivars finely adapted to a warm climate. A competitive agricultural system may consider human well-being, social equity, and conservation of natural resources, to ensure a high level of services for current and future generations. Recovery and conservation of agricultural resources provide positive externalities and social benefits at both local and regional levels. Understanding the multiple use and functions of tree crop landscapes will contribute to improve food security, land quality, and the provision of related ecosystem services

Mixed Land Use as an Intrinsic Feature of Sprawl: A Short-Term Analysis of Settlement Growth and Population Distribution Using European Urban Atlas

This study investigates the land-use/population mix over time as the base to derive an indicator of urban sprawl. Land-use individual patches (provided by Urban Atlas, hereafter UA, with a detailed spatial geometry at 1:10,000 scale) were associated with the total (resident) population based on official statistics (census enumeration districts and other public data sources), providing a comprehensive mapping of the spatial distribution of population density by land-use class in a representative case study for the Mediterranean region (metropolitan Athens, Greece). Data analysis adopted a mix of statistical techniques, such as descriptive statistics, non-parametric curve interpolation (smoothing splines), and exploratory multivariate statistics, namely hierarchical clustering, non-metric multi-dimensional scaling and confirmative factor analysis. The results of this study indicate a non-linear gradient of density decline from downtown (dominated by compact settlements) to peripheral locations (dominated by natural land). Population density in agricultural land was locally high and increasing over time; this result suggests how mixed land use may be the base of intense sprawl in large metropolitan regions. The methodology implemented in this study can be generalized over the whole sample of European cities included in Urban Atlas, providing a semi-automatic assessment of exurban development and population re-distribution over larger metropolitan regions

Rapidity of change in population age structures: A local approach based on multiway factor analysis

In the light of complex adaptive system thinking, population age structures in Europe have increasingly reflected the interplay between 'fast' and 'slow' socioeconomic dynamics driven by natural population growth and migration. Assuming the importance of demographic dynamics shaping regional growth in recent times, a diachronic analysis of local-scale population age structures was developed for 156 districts of Greece between 1971 and 2011. By using appropriate indicators, the analysis was aimed at demonstrating how 'fast' and 'slow' transitions contribute to socioeconomic change in both urban and rural areas. Acomprehensive analysis of change in population age structures between 1971 and 2011 allows identification of latent spatial structures as a result of population re-distribution from urban cores to broader rural regions. Following residential mobility, the empirical results of this study indicate (i) a late phase of urbanization (1971-1981) with population densification and settlement compactness, (i) a rapid suburbanization (1981-1991) consolidating distinctive demographic structures in urban and rural areas, (ii) a mild counter-urbanization (1991-2001) with moderate aging of suburban populations and (iii) a latent re-urbanization (2001-2011) reducing the suburban-urban divide in population age structures. Residential mobility contributed to a more balanced age structure during suburbanization and an increased demographic divide in the subsequent urban waves. A refined analysis of long-term population dynamics in metropolitan regions reflects spatial outcomes and latent aspects of demographic transitions shedding light on the debate over the future development of urban and rural societies in advanced economies

Investigating Metropolitan Hierarchies through a Spatially Explicit (Local) Approach

Assuming a non-neutral impact of space, an explicit assessment of metropolitan hierarchies based on local regression models produces a refined description of population settlement patterns and processes over time. We used Geographically Weighted Regressions (GWR) to provide an enriched interpretation of the density gradient in Greece, estimating a spatially explicit rank–size relationship inspired by Zipf’s law. The empirical results of the GWR models quantified the adherence of real data (municipal population density as a predictor of metropolitan hierarchy) to the operational assumptions of the rank–size relationship. Local deviations from its prediction were explained considering the peculiarity of the metropolitan cycle (1961–2011) in the country. Although preliminary and exploratory, these findings decomposed representative population dynamics in two stages of the cycle (namely urbanization, 1961–1991, and suburbanization, 1991–2011). Being in line with earlier studies, this timing allowed a geographical interpretation of the evolution of a particularly complex metropolitan system with intense (urban) primacy and a weak level of rural development over a sufficiently long time interval. Introducing a spatially explicit estimation of the rank–size relationship at detailed territorial resolutions provided an original contribution to regional science, covering broad geographical scales

Effects of omeprazole on mechanisms of gastroesophageal reflux in childhood

Prolonged recordings of esophageal motility have shown that dynamic changes of lower esophageal sphincter (LES) pressure such as transient LES relaxation and LES pressure drifts are the most common mechanisms underlying gastroesophageal reflux (GER). The coexistence of a delayed gastric emptying has also been reported in a high proportion of patients with reflux disease. However, not much information is available on the effects of antireflux therapy on the pathogenetic mechanisms of GER. The purpose of this study was to determine in a group of children with severe reflux disease the effect of omeprazole therapy on motor changes of LES underlying GER as well as on gastric emptying time. Twenty-two children (median age: 6.6 years) with GER disease, refractory to combined ranitidine and cisapride administration, entered into an eight-week omeprazole course. Ten subjects with moderate GER disease served as controls (median age: 6.0 years). Before and after omeprazole administration, the following variables were assessed: esophagitis grading, fasting and fed simultaneous prolonged recording of distal esophageal sphincter pressure (with a sleeve catheter) and intraesophageal pH, LES and esophageal peristalsis amplitude, and gastric emptying time of a mixed solid-liquid meal (measured with gastric ultrasound). As compared to controls, patients showed a higher rate of transient LES relaxation and LES pressure drift (P < 0.01), a reduced amplitude of basal sphincter pressure (P < 0.01) and peristalsis (P < 0.05), and a more prolonged gastric emptying time (P < 0.05). After ending omeprazole, there was no significant change in any of the motor abnormalities of the esophagus and in gastric emptying time despite a marked improvement of symptoms and esophagitis in all patients. Sixteen patients were symptomatic when reevaluated on a clinical basis two months after ending therapy. We conclude that in children with severe GER disease, an abnormally high rate of both transient LES relaxation and LES pressure drift and slow gastric emptying are not affected by omperazole treatment, even though esophageal mucosal damage is markedly improved or cured. These abnormalities represent a primary motor disorder and can be implicated in the refractoriness of reflux disease

Towards local forms of sprawl: A brief reflection on mediterranean urbanization

Urban sprawl is a complex phenomenon that requires a comprehensive reflection on the most significant patterns and underlying processes. While the "sprawl" notion parallels hegemonic concepts such as economic competitiveness, social cohesion, and polycentric development, an integrated analysis of sprawl patterns and processes in paradigmatic socioeconomic contexts is increasingly required to reconcile dierent disciplinary visions, contributing to a holistic interpretation of metropolitan change. At the same time, sprawl is an increasingly evident product of local socioeconomic contexts all over the world. A comprehensive investigation of multifaceted, form-function relationships underlying sprawl-based on a quali-quantitative analysis of representative cases-is a crucial pre-requisite of both monitoring and policy actions at multiple spatial scales, from urban/regional to national/continental levels. The present contribution proposes a contextualization of the sprawl notion in Southern Europe-a socioeconomic context characterized by compact and continuous urbanization for a long time. An integrated approach based on a visual analysis of urban and peri-urban landscapes-integrated with an extended literature survey-allows for a definition of a specific sprawl model in Southern Europe, sharing some features with the United States ideal type of sprawl and showing peculiarities with respect to common models of urban dispersion typical of Northern and Western Europe. Policies aimed at containing urban dispersion may definitely benefit from a local-based definition of sprawl, considering the specificity of form-function relationships and the underlying socioeconomic context

Lipid digestibility and polyphenols bioaccessibility of oil-in-water emulsions containing avocado peel and seed extracts as affected by the presence of low methoxyl pectin

In this study, the digestibility of oil-in-water (O/W) emulsions using low methoxyl pectin (LMP) as surfactant and in combination with avocado peel (AP) or seed (AS) extracts was assessed, in terms of its free fatty acid (FFA) release and the phenolic compound (PC) bioaccessibility. With this purpose, AP and AS were characterized by UPLC-ESI-MS/MS before their incorporation into O/W emulsions stabilized using LMP. In that sense, AP extract had a higher content of PCs (6836.32 ± 64.66 mg/100 g of extract) compared to AS extract (1514.62 ± 578.33 mg/100 g of extract). Both extracts enhanced LMP’s emulsifying properties, leading to narrower distributions and smaller particle sizes compared to those without extracts. Similarly, when both LMP and the extracts were present in the emulsions the FFA release significantly increased. Regarding bioaccessibility, the PCs from the AS extracts had a higher bioaccessibility than those from the AP extracts, regardless of the presence of LMP. However, the presence of LMP reduced the bioaccessibility of flavonoids from emulsions containing either AP or AS extracts. These results provide new insights regarding the use of PC extracts from avocado peel and seed residues, and the effect of LMP on emulsion digestibility, and its influence on flavonoids bioaccessibility.This study was supported by the Ministry of Economy and Competitiveness, Spain throughout the projects AGL2015-65975-R (MINECO/FEDER, UE) and RTI2018-094268-B-C21 (MINECO/FEDER, UE). Gustavo R. Velderrain-Rodríguez (CVU 426539) also thank to the CONACyT for the postdoctoral gran