Outer Peripheries Research Articles

Flow transitions of head-on vortex ring collisions with contaminated air–water interfaces

An experimental study was conducted on head-on collisions of Re = 2000 and 4000 vortex rings upon air–water interfaces to study the vortex dynamics and the effects of different vortex ring Reynolds numbers on the key vortex flow mechanisms. Unfiltered tap water was used where surface contaminants were present; hence, the interfacial stress levels are lower but not entirely zero like an idealized free surface. Results demonstrate that the vortex dynamics involve first, the resulting secondary and tertiary vortex rings transitioning into wavy states, before their upper loops disconnect/reconnect to the interface to form U-shaped vortex loops along the inner and outer peripheries of the primary vortex ring, respectively, in an alternating pattern. Second, tertiary vortex loops entangle around the primary vortex ring to produce counter-rotating vortex pairs that reorganize themselves along the primary vortex ring outer periphery, between the primary vortex ring and secondary vortex loops, as well as hairpin-like structures that aid ejection of primary vortex ring momentum. Third, secondary vortex loops rotate toward the collision axis before their lower segments are entrained by the primary vortex ring. A higher Reynolds number primary vortex ring would confer additional flow changes, such as a higher wave number for the secondary and tertiary vortex rings/loops, pairings of secondary vortex loops “side-arms” that reduce their instances by about half and formations of Tsai–Widnall–Moore–Saffman instabilities induced by flow perturbations. Finally, vortex flow models proposed to explain the flow mechanism at different flow stages are found to be in good agreements with the experimental visualizations.

Towards a theory of dependent democracy

Democracy is seen today as being in erosion or crisis both in the Global North and South. This article puts forward the concept of ‘dependent democracy’ in order to explain that much of the lack of success of democracy in the South in guaranteeing political participation and economic inclusion and wellbeing for the majority of the population is due to a specific tendency of democracy there. Adapting some insights from the more economics focused Dependency theory towards a more contemporary point of view from political sociology and international political sociology, dependent democracy is understood as a democracy that exists in a subaltern position within the hierarchical, post-imperial and neo-imperial global capitalist order. Dependent democracies thus tend to be less ‘democracies’ and more ‘oligarchies’ within a form of government in the South that can be understood as existing in a global pyramid of semi-peripheries, middle peripheries and outer peripheries.

Features of the organization of the concept Director at different stages of age development

The article is devoted to the study of the features of the concept “Director” at different stages of age development. The study involved 638 respondents (pupils, students, film directors, psychologists) aged from 6 to 80 years. To identify the features of the organization of mental experience, the results of a directed associative experiment were analyzed (stimulus word - Director). The results of the study indicate that, as the age development and the mastering of professional activity, there is an increase in the differentiation and hierarchy of signs - first, the core and the outer periphery are distinguished, then the core, near, far and outer peripheries, and then - the differentiation of signs within the core. In the mature group of respondents and the group of film directors, the differentiation of features decreases, but there is an increase in the integration of features, which manifests itself in a decrease in differences between the core and the center. The basic characteristics of the director's personality are clarified - smart, responsible and creative. A significant predominance of emotional and evaluative features of the concept “Director” was revealed. A hypothesis has been put forward about the relationship between the measure of severity of the emotional and evaluative features of the concept “Director” and the measure of the integration of individual mental experience.

A holistic model of health inequalities for health policy and state administration: a case study in the regions of the Czech Republic

BackgroundHealth inequities exist within and between societies at different hierarchical levels. Despite overall improvements in health status in European Union countries, disparities persist among socially, economically, and societally disadvantaged individuals. This study aims to develop a holistic model of health determinants, examining the complex relationship between various determinants of health inequalities and their association with health condition.MethodsHealth inequalities and conditions were assessed at the territorial level of Local Administrative Units (LAU1) in the Czech Republic. A dataset of 57 indicators was created, categorized into seven determinants of health and one health condition category. The necessary data were obtained from publicly available databases. Comparisons were made between 2001–2003 and 2016–2019. Various methods were employed, including composite indicator creation, correlation analysis, the Wilcoxon test, aggregate index calculation, cluster analysis, and data visualization using the LISA method.ResultsThe correlation matrix revealed strong relationships between health inequality categories in both periods. The most significant associations were observed between Economic status and social protection and Education in the first period. However, dependencies weakened in the later period, approaching values of approximately 0.50. The Wilcoxon test confirmed variations in determinant values over time, except for three specific determinants. Data visualization identified persistently adverse or worsening health inequalities in specific LAU1, focusing on categories such as Economic status and social protection, Education, Demographic situation, Environmental status, Individual living status, and Road safety and crime. The health condition indices showed no significant change over time, while the aggregate index of health inequalities improved with widened differences.ConclusionSpatial inequalities in health persist in the Czech Republic, influenced by economic, social, demographic, and environmental factors, as well as local healthcare accessibility. Both inner and outer peripheries exhibit poor health outcomes, challenging the assumption that urban areas fare better. The combination of poverty and vulnerabilities exacerbates these inequalities. Despite the low rates of social exclusion and poverty, regional health inequalities persist in the long term. Effectively addressing health inequalities requires interdisciplinary collaboration and evidence-based policy interventions. Efforts should focus on creating supportive social and physical environments, strengthening the healthcare system, and fostering cooperation with non-medical disciplines.

Contribution of Rudolf Frič to the social architecture of interwar Czechoslovakia

Abstract Social policy in the interwar Czechoslovakia focused on the development of social housing. In Bratislava the establishment of new institutions and the related arrival of the Czech middle class of civil servants induced social change in the city population and its housing conditions. This necessitated the construction of modern residential blocks, which stabilised the internal urban structure and urbanised the outer city. A significant contribution to that field would be attributed to construction entrepreneur Rudolf Frič. Although the Slovak historiography exclusively presents him as a builder of civil engineering structures, his portfolio was more complex. The aim of the paper is to identify and critically evaluate Frič’s both architectural and construction work in the field of social housing in interwar Bratislava. The study focuses on projects of housing cooperatives, private rental blocks and partly on examples of city social housing. Cooperatives with the highest socio-economic relevance were set by the Bank of Czechoslovak Legions, for which Frič designed or constructed several buildings, such as the residential urban structure “Legiodomy”, housing colony in Koliba or the polyfunctional buildings of Legiopojišťovna and LUXOR. Frič's construction portfolio also includes individual projects of rental houses for smaller cooperatives, both in the compact city centre and at the then urbanising outer city peripheries. A specific case was housing for members of the army, like the residential blocks for military veterans in Bratislava. A critical category was social housing for the poorest and unemployed represented by the City rental house with habitable kitchens and the smallest-size flats. Finally, the paper examines private houses, the rental residential block of Irma Hanke and Helena Hudečková and the Trojan & Švarc polyfunctional department. Frič, as a construction entrepreneur, designed rental houses for his own employees, which all reflect the influence of private investors on the social and urban changes of the then modernising Bratislava metropolis.

Governance Challenge and Tiered State Assistance: The Fiscal Gap in the Chinese Ethnic Tibetan Autonomous Areas

ABSTRACT Contrary to the arguments in most of the literature, the central government of China applies diversified rather than homogenous measures to govern its Ethnic Tibetan Autonomous Areas (ETAA). Applying the analytical framework of ‘inner and outer peripheries’, this research argues that the central government has favoured the Tibetan Autonomous Region (TAR), particularly in state fiscal assistance, over the other ETAAs, due to its unique governance challenge. This research analyses the central government’s fiscal assistance to the ETAAs from 2010 to 2019 and reveals an increasing fiscal gap between them. Not only has the TAR been consistently in the lead but fiscal inequality has also grown among ETAAs in the provinces of Sichuan, Yunnan, Qinghai and Gansu. Fieldwork in the TAR, Yunnan, Gansu and Sichuan reveals that the fiscal gap, combined with varied local circumstances, has created multifaceted social and economic unevenness in the ETAAs.

Long-term demographic trends and spatio-temporal distribution of past human activity in Central Europe: Comparison of archaeological and palaeoecological proxies

Estimating past population dynamics has become a major research topic for archaeology, which uses several proxies for studying past demography. The Czech Republic represents a unique region with abundant digital archaeological and palynological datasets comprising tens of thousands of records covering the whole Holocene. We used these datasets to quantify long-term demographic trends and to delimit past human activity in space and time. Our results, based on large data from both disciplines, are one of the first quantitative results covering the whole Czech Republic. Through summed probability distributions of radiocarbon dates and spatio-temporal modelling of human activity based on archaeological sites, we identified four major demographic events and processes between 10,000 BCE and 1000 CE – the beginning of the Neolithic at 5400 BCE, the Eneolithic/Bronze Age transition in the 3rd millennium BCE, Bronze Age expansion after 1500 BCE, and mediaeval expansion after 500 CE. We identified two settlement cores in the lowlands, with additional inner and outer peripheries with different demographic histories. Our study clearly shows that prehistoric and early historic population dynamics were not a homogenised process and were regionalized according to local environmental and social conditions. The comparison of archaeological results with pollen-based vegetation proxies also showed regional aspects in human-vegetation interactions. Agro-pastoral communities dwelling in the lowlands mostly influenced the openness of the landscape, used for fields and pastures, whereas contemporary communities with a similar economic mode residing in a different region are more visible in pollen records through species and structural changes in woodlands. The agro-pastoral subsistence strategy did not start everywhere with the onset of the Neolithic: in some regions it failed after several centuries, in others, the foraging lifestyle persisted significantly longer, and farming became a major economic strategy much later. Our study shows that archaeological site-based and 14C-based demographic proxies cannot be utilized for all periods and regions due to several limitations. Only the combination of different quantitative and qualitative archaeological proxies for population does reveal important details.

On-Surface Synthesis of C144 Hexagonal Coronoid with Zigzag Edges.

Coronoids as polycyclic aromatic macrocycles enclosing a cavity have attracted a lot of attention due to their distinctive molecular and electronic structures. They can be also regarded as nanoporous graphene molecules whose electronic properties are critically dependent on the size and topology of their outer and inner peripheries. However, because of their synthetic challenges, the extended hexagonal coronoids with zigzag outer edges have not been reported yet. Here, we report the on-surface synthesis of C144 hexagonal coronoid with outer zigzag edges on a designed precursor undergoing hierarchical Ullmann coupling and cyclodehydrogenation on the Au(111) surface. The molecular structure is unambiguously characterized by bond-resolved noncontact atomic force microscopy imaging. The electronic properties are further investigated by scanning tunneling spectroscopy measurements, in combination with the density functional theory calculations. Moreover, the values of the harmonic oscillator model of aromaticity are derived from calculations that suggest that the molecular structure is ideally represented by Clar's model. Our results provide approaches toward realizing a hexagonal coronoid with zigzag edges, potentially inspiring fabrication of hexagonal zigzag coronoids with multiple radical characters in the future.

Microstructure and Fatigue Behaviors of Dissimilar A6061/Galvannealed Steel Joints Fabricated by Friction Stir Spot Welding.

The microstructures, tensile shear properties, and tensile shear fatigue properties of dissimilar A6061/Galvannealed steel joints fabricated by friction stir spot welding (FSSW) were investigated. Fe4Al13 phases form as the intermetallic compound (IMC) layer at the joint interface between the A6061 matrix and the galvannealed layer consisting of FeZn7, Fe, and Zn. At the edge of the joint, the stirred layer in which the A6061 matrix and the galvannealed layer are stirred also forms. Moreover, the solidified part of the residual melt discharged from the joint area forms at the outer peripheries of the joint. In this study, FSSW was conducted for two total welding durations: 9 and 10 s. Although the thickness of the remaining A6061 sheet in the welded area decreased with an increase in the welding time, the effects of the total welding time on tensile shear and tensile shear fatigue properties were negligible. A fatigue fracture occurred in the A6061 matrix and at the joint interface at the high cycle fatigue region and the low cycle fatigue region, respectively. In the case of the interfacial fracture, the crack was generated in the solidified part of the residual melt or at the interface between the solidified part and the stirred layer.

The new delimitation of peripheries in Czechia

Peripheries may be delimited by various methodological approaches. The aim of this article is to identify and spatially determine inner and outer peripheries at the municipal level in Czechia. With the help of 15 indicators (reflecting the demographic development, economic activity, and transportation accessibility), the municipalities are divided into five categories according to the level of their peripherality. The results are then confronted with previous research in this field to assess the dynamics of spatial distribution of peripheries in Czechia, particularly in terms of their location and size.

Facile Synthesis of Aryl-Substituted Cycloarenes via Bismuth(III) Triflate-Catalyzed Cyclization of Vinyl Ethers

Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure, but their synthesis is very challenging. Herein, we report a facile synthetic strategy prima...

The fate of socialist agricultural premises: To agricultural ‘brownfields’ and back again?

Abstract The variety of post-socialist agricultural transitions in four different rural regions located in South Bohemia (Czech Republic), with respect to the utilisation of the older premises, is subject to analysis in this article. A complete database was constructed, containing the identification of agricultural premises in 1989 and their use in 2004 and 2017. From 1989 to 2004, a number of agricultural brownfields emerged, and many sites had been utilised for non-agricultural purposes. After 2004, the acreage of agricultural brownfields was reduced and new land-use utilisation for housing and, especially other non-agricultural activities, significantly increased. The transition in the utilisation of pre-1989 agricultural premises is strongly influenced by the social and economic contexts in which particular sites are located. Proximity to an upper-level regional centre is of crucial importance for decisions with respect to how (and if) the site will be reused. The peripheral location of the site also affects the level and the selection of options for the ways in which particular pre-1989 agricultural premises are used. In the case studies reported here, the marginality of particular regions is increased by their location in the border regions of outer peripheries, where the probability of the presence of agricultural brownfields and the probability of long-term abandonment of agricultural premises is higher. For the traditional developed countryside, we found a typical low level of the share of long-term agricultural brownfields. After 2004, the re-use of pre-1989 agricultural brownfields for agriculture was ascertained, which is complemented by their use for housing.

Dynamic analysis and ecological evaluation of urban heat islands in Raipur city, India

Spatial–temporal distribution of the urban heat islands (UHI) and their changes over Raipur city have been analyzed using multitemporal Landsat satellite data from 1995 to 2016. Land surface temperature (LST) was retrieved through a mono-window algorithm. Some selected land use/land cover (LU–LC) indices were analyzed with LST using linear regression. The urban thermal field variance index (UTFVI) was applied to measure the thermal comfort level of the city. Results show that during the observed period, the study area experienced a gradual increasing rate in mean LST (>1% per annum). The UHI developed especially along the north-western industrial area and south-eastern bare land of the city. A difference in mean LST between UHI and non-UHI for different time periods (2.6°C in 1995, 2.85°C in 2006, 3.42°C in 2009, and 3.63°C in 2016) reflects the continuous warming status of the city. The LST map also shows the existence of a few urban hot spots near the industrial areas, metal roofs, and high density transport parking lots, which are more abundant in the north-western part of the city. The UTFVI map associated with UHI indicates that the inner parts of the city are ecologically more comfortable than the outer peripheries.

Mineral chemistry as a tool for understanding the petrogenesis of Cryogenian (arc-related)–Ediacaran (post-collisional) gabbros in the western Arabian Shield of Saudi Arabia

Metagabbros and gabbros in the Ablah-Shuwas belt (western Saudi Arabia) represent part of significant mafic magmatism in the Neoproterozoic Arabian Shield. The metagabbros are Cryogenian, occasionally stratified and bear calcic amphiboles (hornblende, magnesio-hornblende and actinolite) typical of calc-alkaline complexes. These amphiboles suggest low pressure (~1–3 kbar), high $$f_{{{\text{O}}_{2} }}$$ and crystallization temperature up to 727 °C, whereas it is 247–275 °C in the case of retrograde chlorite. Rutile and titanite in metagabbros are Fe-rich and replace Mn-bearing ilmenite precursors at high $$f_{{{\text{O}}_{2} }}$$ . On the other hand, younger gabbros are fresh, layered and comprised of olivine gabbro and olivine–hornblende gabbro with an uppermost layer of anorthositic gabbro. The fresh gabbros are biotite-bearing. They are characterized by secondary magnetite–orthopyroxene symplectitic intergrowth at the outer peripheries of olivine. The symplectite forms by deuteric alteration from residual pore fluids moving along olivine grain boundaries in the sub-solidus state. In fresh gabbros, ortho- and clinopyroxenes indicate crystallization at 1300–900 and 800–600 °C, respectively. Geochemically, the Cryogenian metagabbros (~850–780 Ma) are tholeiitic to calc-alkaline in composition and interpreted as arc-related. Younger, fresh gabbros are calc-alkaline and post-collisional (~620–590 Ma, i.e., Ediacaran), forming during the late stages of arc amalgamation in the southern Arabian Shield. The calc-alkaline metagabbros are related to a lithospheric mantle source previously modified by subduction. Younger, fresh gabbros were probably produced by partial melting of an enriched mantle source (e.g., garnet lherzolite).

Development of functionally graded aluminium composites using centrifugal casting and influence of reinforcements on mechanical and wear properties

Functionally graded Al/B4C, Al/SiC, Al/Al2O3 and Al/TiB2 composites with constant 12% (mass fraction) of reinforcement were fabricated by centrifugal casting and hollow cylindrical components were obtained. Microstructural characteristics were investigated at outer surface of all composites and segregation of reinforcement particles was observed. Graded property of the composites with different reinforcements was investigated through hardness and tensile measurements. Results revealed that the outer peripheries of all composites exhibit higher hardness except in Al/B4C composite and the outer zones of all composites show higher tensile strength. Abrasive wear test was conducted on the outer peripheries of all composites and Al/TiB2 composite exhibits less wear rate.

Land-Use Planning and Satellite Imagery Used for Green Areas Protection – Case Study of the City of Łódź, Poland

Abstract The article presents the issues of spatial planning on the case study of Łódź. Of significance in Łódź are its outer peripheries, which due to their natural value have become areas that must be protected and monitored in order to limit the anthropogenic impact. Protection of these areas may be carried out through the usage of instruments such as local land-use plans which help to limit the green field development phenomenon and to look after the biologically active surfaces within the borders of the city. The second step which may concern the areas with local land-use plans, as well as those without current local land-use plans, is monitoring. Such monitoring may be carried out through the analyses of satellite imagery of the city area. Such activities are a kind of low-budget enterprises which bring many benefits at a very small cost resulting from the purchase of satellite imagery. From the perspective of the authorities, a crucial fact is that the material collected during the analyses of the satellite imagery may be used in the initial phase of the planning process as an element of the inventory of areas designated for the development of land-use plans.

Pliocene–Quaternary basalts from the Harrat Tufail, western Saudi Arabia: Recycling of ancient oceanic slabs and generation of alkaline intra-plate magma

Harrat Tufail represents a Caenozoic basalt suite at the western margin of the Arabian plate. This rift-related suite includes voluminous Quaternary non-vesicular basalt (with fragments of earlier Pliocene vesicular flow) that forms a cap sheet over Miocene rhyolite and minor vesicular basalt. The contact between rhyolite and the basaltic cap is erosional with remarkable denudations indicating long time gap between the felsic and mafic eruptions. The geochemical data prove alkaline, sodic and low-Ti nature of the olivine basalt cap sheet. The combined whole-rock and mineral spot analyses by the electron microprobe (EMPA) suggest magma generation from low degree of partial melting (∼5%) from spinel- and garnet-lherzolite mantle source. Derivation from a mantle source is supported by low Na content in clinopyroxene (ferroan diopside) whereas high Mg content in ilmenite is an evidence of fractional crystallization trajectory. Accordingly, the Pliocene basaltic cap of Harrat Tufail is a product of mantle melt that originates by recycling in the asthenosphere during subduction of ancient oceanic slab(s). The whole-rock chemistry suggests an ancient ocean island basaltic slab (OIB) whereas the EMPA of Al-rich spinel inclusions in olivine phenocrysts are in favour of a mid-ocean ridge basaltic source (MORB). Calculations of oxygen fugacity based on the composition of co-existing Fe–Ti oxide suggest fluctuation from highly to moderately oxidizing conditions with propagation of crystallization (log10 fO2 from −22.09 to −12.50). Clinopyroxene composition and pressure calculation indicates low-pressure (0.4–2 kbar). Cores of olivine phenocrysts formed at highest temperature (1086–1151 °C) whereas the rims and olivine micro-phenocrysts formed at 712–9–796 °C which is contemporaneous to formation of clinopyroxene at 611–782 °C. Fe–Ti oxides crystallized over a long range (652–992 °C) where it started to form at outer peripheries of olivine phenocrysts and as interstitial phase with clinopyroxene.

Nanocone formation on ion-bombarded InP surfaces

Surfaces of InP(100) were bombarded by 2.1keV Ar+ ions under normal incidence. The total accumulated ion fluence the samples were exposed to was varied roughly from 1×1017cm−2 to 3×1018cm−2 while ion fluxes in the range of (0.1−2)×1014cm−2s−1 were used. The surface morphology resulting from these ion irradiations was examined by scanning electron microscopy (SEM). For a specific range of ion fluxes and fluences, regular closely-spaced nanocone arrays are found to form, with the cones having typical base diameters of about 100nm. Around their outer peripheries, they commonly exhibit rather distinct protrusions, an observation not reported in previous investigations. The inspection of the initial stages of nanocone formation indicates that the growth of adatom islands, first on the pristine surface and later on previously formed islands, may lead to these 3D nanostructures. This finding would imply that surface diffusion processes of adatoms constitute an important mechanism in the evolution of the observed topography.

Constrained Clar Formulas of Coronoid Hydrocarbons

Aromatic character of coronoid hydrocarbons is greatly influenced by the shapes of outer and inner peripheries. The most aromatic rings in coronoids are jutting benzene rings on the armchair edges, if any. Clar formulas of many coronoids conform to the aromaticity patterns. However, placement of all aromatic sextets on highly aromatic rings is sometimes forbidden by the presence of the central cavity. The magnitude of aromatic stabilization energy due to macrocyclic conjugation [SSE(mc)] and the NICS(1) value at the center of the cavity strongly depend on the structure of the superposed Clar formula. Localization of π-electrons in fixed aromatic sextets effectively suppresses macrocyclic conjugation. The sign of SSE(mc) is determined by the number of carbon atoms that form the hub cycle.

Coexistence of Helical Morphologies in Columnar Stacks of Star-Shaped Discotic Hydrazones

Discotic hydrazone molecules are of particular interest as they form discotic phases where the discs are rigidified by intramolecular hydrogen bonds. Here, we investigate the thermotropic behavior and solid-state organizations of three discotic hydrazone derivatives with dendritic groups attached to their outer peripheries, containing six, eight, and ten carbons of linear alkoxy chains. On the basis of two-dimensional wide angle X-ray scattering (2DWAXS), the elevated temperature liquid crystalline (LC) phases were assigned to a hexagonal columnar (Colh) organization with nontilted hydrazone discs for all three compounds. With WAXS, advanced solid-state nuclear magnetic resonance (SSNMR) techniques, and ab initio computations, the compounds with six and ten carbons of achiral alkoxy side chains were further subjected to studies at 25 °C, revealing complex crystalline phases with rigid columns and flexible side chains. This combined approach led to models of coexisting helical columnar stacking morphologies for both systems with two different tilt/pitch angles between successive hydrazone molecules. The differences in tilt/pitch angles between the two compounds illustrate that the columns with short alkoxy chains (six carbons) are more influenced by the presence of other stacks in their vicinity, while those with long side chains are less tilted due to a larger alkoxy (ten carbons) buffer zone. The formation of different packing morphologies in the crystalline phase of a columnar LC has rarely been reported so far, which suggests the possibility of complex stacking structures of similar organic LC systems, utilizing small molecules as potential materials for applications in organic electronics.