Islands Of Various Sizes Research Articles

Transport dynamics in a complex coastal archipelago

Abstract. The Archipelago Sea (in the Baltic Sea) is characterised by thousands of islands of various sizes and steep gradients of the bottom topography. Together with the much deeper Åland Sea, the Archipelago Sea acts as a pathway to the water exchange between the neighbouring basins, Baltic proper and Bothnian Sea. We studied circulation and water transports in the Archipelago Sea using a new configuration of the NEMO 3D hydrodynamic model that covers the Åland Sea–Archipelago Sea region with a horizontal resolution of around 500 m. The results show that currents are steered by the geometry of the islands and straits and the bottom topography. Currents are highest and strongly aligned in the narrow channels in the northern part of the area, with the directions alternating between south and north. In more open areas, the currents are weaker with wider directional distribution. During our study period of 2013–2017, southward currents were more frequent in the surface layer. In the bottom layer, in areas deeper than 25 m, northward currents dominated in the southern part of the Archipelago Sea, while in the northern part southward and northward currents were more evenly represented. Due to the variation in current directions, both northward and southward transports occur. During our study period, the net transport in the upper 20 m layer was southward. Below 20 m depth, the net transport was southward at the northern edge and northward at the southern edge of the Archipelago Sea. There were seasonal and inter-annual variations in the transport volumes and directions in the upper layer. Southward transport was usually largest in spring and summer months, and northward transport was largest in autumn and winter months. The transport dynamics in the Archipelago Sea show different variabilities in the north and south. A single transect cannot describe water transport through the whole area in all cases. Further studies on the water exchange processes between the Baltic proper and the Bothnian Sea through the Archipelago Sea would benefit from using a two-way nested model set-up for the region.

Histological examination of cranial synchondroses as functionally significant elements in the cranial osteopathic concept

Introduction. In recent decades, medical science has accumulated convincing evidence of the fact that the normal activity of a human brain depends on the functional integration of its vascular system, a circulation system of cerebrospinal fluid and biomechanical features of a skull, forming a single structural and functional system.The aim of the study is to research the histological structure of functionally significant cranial synchondroses in the middle and elderly age group, to find possible points of osteopathic influence application in their structure. Materials and methods. The study was performed on cadaver material of 27 persons (7 men — 26 %, 20 women — 74 %) who died at the age from 49 to 66 years (57,5±5,3 years) from various somatic pathologies, but had no history of craniocerebral injuries with fractures of osseous structures. Small bone fragments with sutures of interest/synchondroses (spheno-occipital synchondrosis, petro-jugular synchondrosis, sphenopetrosal synchondrosis) were subjected to standard histological processing followed by microscopy.Results. Evaluating histological specimens of spheno-occipital synchondrosis, we observed the similar pattern: highly mineralized tissues at the edges of the bodies of the sphenoid and occipital bones were connected without elements of cartilagi-nous or connective tissue. In all cases, no fibrous or nerve tissue elements were found during the in situ immunohistochemical reactions. Reactions with the CD34 antibody mark multiple vessels of the Volkmann's or Haversian canals. Evaluating histological specimens of petro-jugular and sphenopetrosal synchondroses, we found the presence of cartilage tissue in the suture in the form of small islands of various sizes (from 20 to 120 microns) with signs of degeneration and a small number of remained chondrocytes. When evaluating specimens with immunohistochemical reactions with antibodies against the S100 protein, no elements of the nervous tissue were detected.Conclusion. Spheno-occipital synchondrosis has a temporary nature. With age, its cartilaginous tissue is replaced by osseous one. According to the histological structure, sphenobasilar synchondrosis demonstrates the complete absence of a cartilaginous component in the middle and elderly age groups. Petro-jugular and sphenopetrosal synchondroses retain the cartilaginous component in their suture throughout lifetime. During histological examination of the petro-jugular and sphenopetrosal synchondroses, the cartilaginous component is represented by variety of small islands. In all synchondroses, there is an absence of vascular and nervous components. At the same time, we revealed the presence of a prominent vascular bed in the bone tissue. The fact requires emphasizing the importance of liquid potency and elastic component in cartilaginous and osseous tissues as an application point for osteopathic techniques.

Can Off-grid Islands Powered by Renewable Energy Microgrids be Operated Sustainably without Subsidies? A Techno-economic Case Study in the Philippines

The Philippines is home to thousands of off grid islands that are too distant from the mainland and consequently expensive to connect to the main grid. These islands are typically powered by diesel generators, which will require more subsidies as fuel costs continue to increase. Hybrid renewable energy systems (HRES) are an alternative energy source with lower reliance on fuel and generation costs. In this work, the financial sustainability of deploying HRES in Philippine off grid islands of various sizes was evaluated. Patongong Island, Lapinigan Island, Balabac Island, and Sibuyan Island were selected as case studies as their peak electrical demand varies from 4.4 kW in Patongong Island to 3.2 MW in Sibuyan Island, representing a large fraction of off-grid islands in the country. HRES consisting of solar photovoltaics, wind turbines, lithium ion batteries, and diesel generators in these islands were modeled in Island Systems LCOEmin Algorithm (ISLA), an in house energy systems modeling tool. Profitability metrics, such as the net present value, internal rate of return (IRR), and payback period (PBP), were then calculated at varying electricity prices. The large Sibuyan island was already profitable at 0.2 USD/kWh, comparable to the mainland rate, which suggests that subsidies in large islands can be removed. The low 11 % IRR and 13 year PBP may not be attractive to private investors, but this may be alleviated by raising electricity prices. Other islands, however, will still require subsidies as the small Patongong Island becomes profitable only at 1.5 times the mainland rate. This work encourages private sector participation by providing financial insights absent in many techno economic studies. Moreover, this study enlightens the public sector about the necessity of subsidies for providing energy access in small off grid islands.

Distance-dependent seed\u2012seedling transition in the tree Castanopsis sclerophylla is altered by fragment size

Negative distance-dependence of conspecific seedling mortality (NDisDM) is a crucial stabilizing force that regulates plant diversity, but it remains unclear whether and how fragment size shifts the strength of NDisDM. Here, we surveyed the seed‒seedling transition process for a total of 25,500 seeds of a local dominant tree species on islands of various sizes in a reservoir and on the nearby mainland. We found significant NDisDM on the mainland and large and medium islands, with significantly stronger NDisDM on medium islands. However, positive distance-dependent mortality was detected on small islands. Changes in distance-dependence were critically driven by both rodent attack and pathogen infestation, which were significantly affected by fragment size. Our results emphasize the necessity of incorporating the effects of fragment size on distance-dependent regeneration of dominant plant species into the existing frameworks for better predicting the consequences of habitat fragmentation.

Modeling diploid male dynamics in Hymenoptera: Effects of the number of alleles, dispersal by random walk and simple spatial structuring

Insects in the order Hymenoptera such as wasps, ants and bees exhibit a haplodiploid system of sexual determination in which females result from fertilized eggs and males from unfertilized eggs. Genetic information for sex determination is contained in a single multiallelic locus, so that the heterozygous individuals become females, and the hemizygous or homozygous individuals, haploid or diploid males, respectively. This mechanism is called single locus complementary sex determination (sl-CSD). While females and haploid males are regarded to be fertile, the opposite occurs for diploid males, so the significant production of diploid males (DM) may lead a population to an extinction scenario called the “diploid male vortex”. In the present work, we investigate the dynamics of populations of an organism with sl-CSD under various combinations of three parameters: male flight skills, number of sexual alleles and concentration of prohibited zones in a terrain represented by a square lattice. Sites of this lattice were randomly chosen as prohibited, where individuals could not pass, so the terrain was divided into islands of various sizes where individuals were confined. After a given simulation, the number of DM was measured. The main results that come from our simulations are: (i) the DM number depends more on the number of random steps in the male flight than on the number of alleles; (ii) the DM frequency in the small fragments becomes the same as the entire network when the limit of percolation is reached; (iii) the number of random steps explains the difference between the DM number found in the largest fragment and in the small fragments when the limit of percolation is reached.

Patch and landscape effects on forest-dependent dung beetles are masked by matrix-tolerant dung beetles in a mountaintop rainforest archipelago

Naturally fragmented landscapes provide suitable scenarios through which to investigate patch and landscape effects on biodiversity patterns in areas that are isolated from the disturbances usually associated with human-made fragments. We aimed to investigate the patch and landscape effects on the diversity of forest-dependent and matrix-tolerant dung beetles in a naturally fragmented landscape. We also assessed the influence that seasonal and vegetation variations had on these dung beetles. We sampled dung beetles during two summers and two winters in 14 forest islands of various sizes and shapes within a natural mountainous forest archipelago in southeast Brazil. We measured the patch and landscape variables based on high-resolution multispectral images of circular sectors with radii of 100, 250, and 500 m. We used generalized linear mixed models to relate dung beetle metrics to patch and landscape attributes. The interaction between canopy cover and season influenced both species' richness and abundance of the dung beetle metacommunity. The forest-dependent species' richness increased with greater canopy cover, regardless of the season. Patch attributes (e.g., size, canopy cover, distance to the closest patch, and distance to continuous forest) and landscape attributes (e.g., percentage of forest in the landscape, total edge, number of patches, distance to the nearest neighbor, and shape complexity) had small general effects on dung beetle species as a whole and on matrix-tolerant species in particular. However, these values strongly influenced forest-dependent species' richness, abundance, and temporal beta diversity. The matrix-tolerant species, therefore, mask the effects of patch and landscape effects on forest-dependent species within the mountainous forest archipelago. In other words, the changes in these patch and landscape attributes influenced forest-dependent and matrix-tolerant species differently. Therefore, the evaluation of entire metacommunities may not be helpful when evaluating species-specific responses in mixed landscapes—a fact that impairs the conservation of forest-dependent species.

Even the smallest non-crop habitat islands could be beneficial: distribution of carabid beetles and spiders in agricultural landscape.

Carabid beetles and ground-dwelling spiders inhabiting agroecosystems are beneficial organisms with a potential to control pest species. Intensification of agricultural management and reduction of areas covered by non-crop vegetation during recent decades in some areas has led to many potentially serious environmental problems including a decline in the diversity and abundance of beneficial arthropods in agricultural landscapes. This study investigated carabid beetle and spider assemblages in non-crop habitat islands of various sizes (50 to 18,000 square metres) within one large field, as well as the arable land within the field, using pitfall traps in two consecutive sampling periods (spring to early summer and peak summer). The non-crop habitat islands situated inside arable land hosted many unique ground-dwelling arthropod species that were not present within the surrounding arable land. Even the smallest non-crop habitat islands with areas of tens of square metres were inhabited by assemblages substantially different from these inhabiting arable land and thus enhanced the biodiversity of agricultural landscapes. The non-crop habitat area substantially affected the activity density, recorded species richness and recorded species composition of carabid and ground-dwelling spider assemblages; however, the effects were weakened when species specialised to non-crop habitats species were analysed separately. Interestingly, recorded species richness of spiders increased with non-crop habitat area, whereas recorded species richness of carabid beetles exhibited an opposite trend. There was substantial temporal variation in the spatial distribution of ground-dwelling arthropods, and contrasting patterns were observed for particular taxa (carabid beetles and spiders). In general, local environmental conditions (i.e., non-crop habitat island tree cover, shrub cover, grass cover and litter depth) were better determinants of arthropod assemblages than non-crop habitat island size, indicating that the creation of quite small but diversified (e.g., differing in vegetation cover) non-crop habitat islands could be the most efficient tool for the maintenance and enhancement of diversity of ground-dwelling carabids and spiders in agricultural landscapes.

Kinetically driven shape changes in early stages of two-dimensional island coarsening: Ag/Ag(111)

We present here a detailed analysis of the shapes of two-dimensional Ag islands of various sizes observed during the early stages of coarsening on the Ag(111) surface, using kinetic Monte Carlo (KMC) simulations, and show that selectivity is due to the formation of kinetically stable island shapes that survive longer than nonselected sizes, which decay into nearby selected sizes. The stable shapes have a closed-shell structure---one in which every atom on the periphery has at least three nearest neighbors. These findings further explain our earlier study in which we found that in the early stages coarsening proceeds as a sequence of selected island sizes resulting in peaks and valleys in the island size distribution [G. Nandipati, A. Kara, S. I. Shah, and T. S. Rahman, J. Phys.: Condens. Matter 23, 262001 (2011)]. This selectivity is dictated by the relative energetics of edge-atom diffusion and detachment and attachment processes and by the large activation barrier for kink detachment. Our simulations were carried out using a very large database of processes identified by each atom's unique local environment using the self-learning KMC scheme. The activation barriers were calculated using semiempirical interaction potentials based on the embedded-atom method.

Self-diffusion of small Ni clusters on the Ni(111) surface: A self-learning kinetic Monte Carlo study

We studied self-diffusion of small 2D Ni islands (consisting of up to 10 atoms) on Ni (111) surface using a self-learning kinetic Monte Carlo (SLKMC-II) method with an improved pattern-recognition scheme that allows inclusion of both fcc and hcp sites in the simulations. In an SLKMC simulation, a database holds information about the local neighborhood of an atom and associated processes that is accumulated on-the-fly as the simulation proceeds. In this study, these diffusion processes were identified using the drag method, and their activation barriers calculated using a semi-empirical interaction potential based on the embedded-atom method. Although a variety of concerted, multi-atom and single-atom processes were automatically revealed in our simulations, we found that these small islands diffuse primarily via concerted diffusion processes. We report diffusion coefficients for each island size at various tepmratures, the effective energy barrier for islands of each size and the processes most responsible for diffusion of islands of various sizes, including concerted and multi-atom processes that are not accessible under SLKMC-I or in short time-scale MD simulations.

Malignant Pilomatricoma in a Dog

An 11-year-old female German shepherd dog was presented with a history of lameness and pain in the left forelimb. Clinical examination revealed ataxia of the hindlimbs and a subcutaneous mass in the left prescapular region. Radiography revealed metastatic foci in the left humerus, lung and abdomen. Gross necropsy examination revealed a firm, white mass in the left prescapular region. Multiple nodules with similar characteristics were observed in the lung, liver and spleen. Bone lysis was noted in the humerus and the fifth to seventh lumbar vertebrae. Microscopical examination revealed a proliferation of basal cells forming irregular islands of various sizes and surrounding extensive zones of keratinized 'ghost' cells. A definitive diagnosis of malignant pilomatricoma was made. This is a rare tumour in dogs with no previous report of metastasis to the spleen and liver.

Direct Observation and Measurement of Mobile Charge Carriers in a Monolayer Organic Semiconductor on a Dielectric Substrate

We report the electrical characterization of a single layer of an organic semiconductor grown on a dielectric surface. The dynamic response of the charge carriers in the monolayer film of pentacene was characterized through the electrostatic interactions between an electric force microscope (EFM) probe and pentacene islands of various sizes. These islands were formed in situ by segmenting a coalesced pentacene monolayer into separated regions. The size-dependent dielectric responses of the pentacene islands suggest that mobile charges exist in the organic monolayer. Local capacitance spectroscopy revealed that the charge carriers in the p-type pentacene monolayer could be depleted at high bias voltages, enabling a further determination of the charge-carrier concentration in the organic semiconductor ultrathin film.

Structural evolution of GaN layers grown on (0 0 0 1) sapphire by hydride vapor phase epitaxy

GaN was grown directly on (0 0 0 1) sapphire by a two-step process using hydride vapor phase epitaxy (HVPE). Nucleation layers deposited on sapphire at ∼450–500 °C consisted of localized epitaxial wurtzite GaN nano-crystals. In between and above the epitaxial nano-crystals were randomly oriented wurtzite GaN nano-crystals. GaN islands of various sizes and shapes were formed, after annealing between ∼900 and 1000 °C, through a decomposition–redeposition process. Preferential growth of GaN occurred on the islands that had an epitaxial relationship with sapphire during the subsequent high-temperature overgrowth. Threading dislocations were observed in isolated GaN islands that were formed after annealing.

Insights into the Roles of Non-Muscle Myosin IIA in Human Keratinocyte Migration

Epidermal cell migration is a key factor in wound healing responses, regulated by the F-actin-myosin II systems. Previous reports have established the importance of non-muscle myosin II (NMII) in regulating cell migration. However, the role of NMII in primary human keratinocytes has not been investigated. In this study we used a microfabrication-based two-dimensional migration assay to examine the role of NMII in keratinocyte migration. We developed confluent cell islands of various sizes (0.025 - 0.25 mm(2)) and quantified migration as Fold Increase in island area over time. We report here that NMII was expressed and activated in migrating keratinocytes. Inhibition of NMIIA motor activity with blebbistatin increased migration significantly in all cell island sizes in six hours compared to control. Inhibition of Rho-kinase by Y-27632 did not alter migration while inhibition of myosin light chain kinase by ML-7 suppressed migration significantly in six hours. Both blebbistatin and Y-27632 induced formation of large membrane ruffles and elongated tails. In contrast, ML-7 blocked cell spreading, resulting in a rounded morphology. Taken together, these data suggest that NMIIA decreases migration in keratinocytes, but the mechanism may be differentially regulated by upstream kinases.

Thin films of porphyrin molecules imaged with the atomic force microscope

The assembly of two-dimensional molecular structures of zinc porphyrin molecules arising from the dewetting of a porphyrin solution on mica and graphite is investigated using atomic force microscopy. Both a near equilibrium nucleation and growth process, and a far from equilibrium spinodal dewetting process are observed. Nucleation and growth around pre-existing surface defects on mica produces single layer disks, ∼ 10 μm in diameter, of densely packed molecules. Spinodal dewetting gives rise to the formation of much smaller, single layer, molecular islands of various sizes on both mica and graphite.

Present situation and future prospects of electricity generation in Aegean Archipelago islands

The Aegean Archipelago is a remote Hellenic area, including several hundreds of scattered islands of various sizes. In these islands more than 600,000 people are living mainly in small remote communities. The main economical activities of the islanders are apart from tourism, seafaring, fishery, agriculture and stock farming. One of the major problems of the area is the insufficient infrastructure, strongly related with the absence of an integrated and cost-effective electrification plan. In this context, the present work is concentrated on analyzing the present situation and demonstrating the future prospects of electricity generation in the Aegean Archipelago islands. For this purpose, one should first investigate the time evolution of the corresponding electricity generation parameters (i.e. annual electricity consumption, peak power demand, capacity factor, specific fuel consumption) for the last 30 years. Subsequently, the corresponding diesel and heavy-oil consumption along with the electricity production cost for every specific autonomous power station of the area are investigated. Special attention is paid in order to estimate the contribution of renewable energy sources (RES) in the energy balance of each island. Finally, an attempt is made to describe in brief the most realistic electricity production solutions available, including the operation of hybrid RES-based power plants in collaboration with appropriate energy storage facilities. Additionally, the idea of connecting the islands of the area with the mainland and interconnecting them is also taken into consideration.

High resolution magnetic force microscopy study of e-beam lithography patterned Co∕Pt nanodots

E-beam lithography has been used to pattern a continuous Co∕Pt multilayer film with perpendicular anisotropy into circular islands of various sizes down to 25nm diameter on a 60nm pitch. High resolution magnetic force microscopy with in situ applied field has been used to directly determine the switching field distribution (SFD) and hysteresis loop of the islands. For the smallest islands, the coercivity is reduced and the width of the SFD is increased, indicating that they would not be well suited to data storage applications.

The effects of neighbouring tree islands on pollinator density and diversity, and on pollination of a wet prairie species, Asclepias lanceolata (Apocynaceae)

Summary The Everglades (Florida, USA) is a mosaic of different habitats. Tropical and temperate trees grow on patches of high ground (tree islands) surrounded by lower elevation wetland communities (marl prairie). Tree islands of various sizes provide nesting substrate, larval host plants and floral resources for insect pollinators. Herbaceous plants in the open surrounding wetlands may also depend on these pollinators. We investigated pollinator diversity and abundances in both tree island and marl prairie habitats using transect sampling methods and estimated pollination success of the milkweed Asclepias lanceolata, an insect‐pollinated marl prairie species, in relation to distance from and size of the closest tree island. On a total of 11 bayhead tree islands, we found that insect diversity and abundance were greater on the edge of larger tree islands (20–30 m2) than on smaller tree islands (5–10 m2). Pollinator diversity and abundance in the marl prairie decreased with increasing distance from tree islands. Pairs of potted A. lanceolata plants were placed in the marl prairie at distances up to 1000 m from small and large tree islands. Fruit and seed production were highest for plants placed less than 25 m from tree islands and decreased with increasing distance. Our results suggest that tree islands are an important source of pollinators for the plants in the tree island and surrounding wetland habitats. This landscape‐based study illustrates how overall landscape structure affects important biotic interactions, particularly plant–pollinator relationships. Our findings have far‐reaching ecological implications for the reproductive success of plants in small, isolated populations that may depend on insect vectors for pollination.

InN Nanostructures: Strain and Morphology

ABSTRACTWe presented an experimental work on InN nanostructures grown on a GaN buffer layer deposited on sapphire (0001) by Metal Organic Vapor Phase Epitaxy. InN islands of controlled sizes were fabricated by using specific growth conditions and taking advantage of self-organization that results from Stranski-Krastanov growth mode. Then nanometric islands as small as 25 nm were characterized by using atomic force microscopy (AFM) and micro-Raman spectroscopy. AFM measurements revealed that the current shape of islands correspond to truncated hexagons. In-plane residual strain field was deduced from the E2 phonon frequency shift in micro-Raman spectra recorded on islands of various sizes. Careful analysis of these data made clear that the key parameter in determining the strain magnitude was the height of the islands: this was not surprising, keeping in mind that the shape was roughly independent of the size. Nevertheless, the dislocation density was believed to increase as function of the island thickness, leading to various degrees of strained relaxation, as probed by the present micro-Raman study. This conclusion was reinforced by the strain variation on the facets of single islands with respect to its value at the centre.

Time correlations and statistics of atomistic processes in island diffusion on fcc [formula omitted] metal surfaces

The diffusion of 2D adatom islands on fcc(1 0 0) metal surfaces has recently been studied with large-scale Monte Carlo simulations of a lattice-gas model, with energetics based on effective medium theory calculations. It has been shown that in the limit of large islands the diffusive motion crosses over from periphery dominated mechanism to a regime where vacancies diffuse inside the island. Here we consider the role and statistics of various atomistic processes for diffusion of islands of various sizes. This analysis reveals the nature of the crossover behavior in terms of the underlying microscopic processes. We also study the memory effects by examining the temporal behavior of the velocity autocorrelation function. It reveals that there are no anomalities in the long-time correlations of the microscopic processes.

Patterning and Composition Arrays of Supported Lipid Bilayers by Microcontact Printing

Fluid-supported lipid bilayers self-assemble on glass and SiO2 surfaces. We have found that it is also possible to assemble fluid bilayers on plasma-oxidized polydimethyl siloxane (PDMS) surfaces. Furthermore, it is possible to transfer or print the supported bilayer from raised PDMS surfaces, such as are typically used for microcontact printing, to fresh glass surfaces creating a supported bilayer membrane replica of the patterned PDMS surface on glass. These patterned islands of bilayer are fully fluid and indefinitely stable under water. The pattern is erased upon addition of more vesicles leaving a continuous bilayer surface. By printing membrane islands of various sizes onto a glass surface that is prepatterned with a material that forms permanent barriers to lateral diffusion and then backfilling the open region with vesicles, it is possible to create arbitrary concentration or composition arrays of membrane-associated components. These arrays may be useful for studies of membrane biophysics, for high throughput screening of compounds that target membrane components, and for probing and possibly controlling living cell−synthetic membrane interactions.