Island Size Research Articles

Plasma self-driven current in tokamaks with magnetic islands

Abstract Magnetic island perturbations may cause a reduction in plasma self-driven current that is needed for tokamak operation.
 A novel effect on tokamak self-driven current revealed by global gyrokinetic simulations is due to magnetic-island-induced
3D electric potential structures, which have the same dominant mode numbers as that of the magnetic island,
whereas centered at both the inner and outer edge of the island. The non-resonant potential islands
are shown to drive a current through an efficient nonlinear parallel acceleration of electrons.
In large aspect ratio (large-A) tokamak devices, this new effect can result in a significant
global reduction of the electron bootstrap current when the island size is sufficiently large,
in addition to the local current loss across the island region due to the pressure profile flattening.
It is shown that there exists a critical magnetic island width for large-A tokamaks beyond which
the electron bootstrap current loss is global and increases rapidly with the island size.
As such, this process may introduce a size limit for tolerable magnetic islands in large-A tokamak
devices in the context of steady state operation. On the other hand, the current loss caused by magnetic islands in
low-A tokamaks such as spherical tokamak (ST) NSTX/U is minor.
The reduction of the axisymmetric current by magnetic islands scales with the square of island width.
However, the loss of the current is mainly local to the island region, and the pace of current
loss as the island size increases is substantially slower compared to large-A tokamaks.
In particular, the bootstrap current reduction in STs is even smaller in the reactor-relevant
high-$\beta_p$ regime where neoclassical tearing modes are more likely to develop.

Island Biogeography Theory and the Island Rule in Orchid Bees in Panama

ABSTRACTAimThe study of the theory of island biogeographic (TIB) has focused mainly on plants and vertebrates, with support for the predictions that species richness decreases with distance from the mainland and increases with island size. However, less work has been done on invertebrates. Similarly, the study of the island rule has been studied mainly in vertebrates. A group of invertebrates that can facilitate the study of TIB and the island rule are orchid bees (Apidae: Euglossini), because they are easily collected and show powerful flight performances that allows them to travel long distances. We wondered if these bees would follow the predictions of island biogeography, given that their populations may not be isolated across islands. To test if there is an homogenitazion of orchid bee communities across islands, we evaluated orchid bees abundance and species composition across islands. Besides, we tested the island rule by examining body size variations in individuals collected across islands.LocationCoiba National Park (Panama).Time PeriodMay and June 2023.TaxaOrchid bees (Hymenoptera: Apidae: Euglossini).MethodsBy using traps with chemical attractants, we sampled male bees from five islands and the mainland in Coiba National Park in the Pacific side of Panama. We tested the TIB by evaluating whether richness decreased with distance from the mainland or whether increased with island area. To investigate the island rule, and whether there is variation in body size across islands, we used Euglossa imperialis and Euglossa mixta as models, the two most abundant species in the study area.ResultsFor the overall orchid bee community, we found that our results fit one of the predictions of IBT, increases in orchid bee abundance with island area; however, species richness did not decrease with isolation and did not increase with island area as predicted by TIB. An interesting result was that as distance from the mainland increased few species became more dominant. Regarding the island rule, we found in the two Euglossa species a marked pattern of reduction in body size as distance from the mainland increased, which seems to outweigh the effect of island size, since the largest island and one of the farthest showed some of the smallest body sizes.Main ConclusionsWhether euglossine bees travel long distances across islands in marine environments remain unclear. As distance from the mainland increases, few species become dominant, which may be caused by a decrease of resources that favours generalist species. This increase in abundance may explain the decrease in body size with isolation, as perhaps competition for resources increases. Our study provides novel insights to better appraise the dynamics of orchid bees' communities in insular habitats.

Application of three-dimensional MHD equilibrium calculation coupled with plasma response to island divertor experiments on J-TEXT

Three-dimensional (3D) equilibrium calculations, including the plasma rotation shielding effect to resonant magnetic perturbations (RMPs) produced by the island divertor (ID) coils, were carried out using the HINT and MARS-F codes on J-TEXT. Validation of 3D equilibrium calculations with experimental observations demonstrates that the shielding effect will prevent the penetration of the edge m/n = 3/1 mode component when the ID coil current is 4 kA, while change the size of magnetic islands once the current exceeds the penetration threshold. This indicates that equilibrium calculations including the plasma rotation shielding effect to RMPs can lead to better agreements with experimental observations compared to the vacuum approximation method. Additionally, the magnetic topology at the boundary undergoes changes, impacting the interaction between the plasma and the target plate. These results may be important in understanding RMP effects on edge transport and magnetohydrodynamic (MHD) instability control, as well as divertor heat and particle flux distribution control.

Island change framework defines dominant modes of atoll island dynamics in response to environmental change

Climatic change threatens the persistence of atoll islands and the cultural and ecosystem services they support. However, adaptation and ecosystem management are constrained by lack of knowledge of island-specific transformations. We present an empirically-based island change framework that characterises the physical trajectory of islands, based on high-resolution shoreline analysis on 509 atoll islands in the central Pacific over the past half-century. Using changes in island size and position we identify seven distinct styles of island transformation in the Pacific, including contraction (21.4%), stability (46.1%) and expansion (32.4%), and show that 40% of islands are currently mobile on reef surfaces. Results challenge the framing of islands as erosional, which misrepresents island behaviour and constrains understanding of island futures. The island change framework highlights a broader set of island-specific management considerations, and opportunities, that scale with the style and rate of island change, and provides an empirical basis to inform management.

Bi-intercalated epitaxial graphene on SiC(0001)

Abstract The intercalation of graphene with suitable atomic species is one of the most frequently applied methods to decouple the graphene layer from the substrate in order to establish the classical electronic properties of graphene. In this context, we studied the bismuth (Bi) intercalation of the (6√3×6√3)R30° reconstructed so-called "zeroth layer graphene'' on SiC(0001). 
As reported earlier by Sohn et al. [J. Korean Phys. Soc. 78, 157 (2021)], two phases are formed depending on the amount of intercalated Bi, which in turn is controlled by the annealing temperature: The α phase, showing a 1×1 periodicity with respect to the substrate, and, at higher temperatures, the √3×√3 reconstructed β phase. We characterise both phases and the transformation from the α to the β phase by photoelectron spectroscopy, normal incidence x-ray standing waves, electron diffraction and electron microscopy. We clearly see an almost complete intercalation of the graphene layers in both phases, with strong (covalent) interaction between the topmost Si atoms of the substrate and the Bi intercalant, but only weak (van der Waals) interaction between Bi and the graphene layer. The n-doping of the graphene found for the α phase decreases continuously during the phase transformation, in agreement with a reduced density of the Bi intercalating layer. Missing core level shifts of the surface species as well as the normal incidence x-ray standing waves results indicate that all surface Si atoms remain saturated during the transition and no dangling bonds are formed. Low energy electron microscopy and diffraction reveal the coexistance of both phases after annealing to intermediate temperatures and allow a quantitative analysis of island sizes and numbers.

On the Conservation of the Canarian Laurel Forest: What Do Lichens Have to Say?

The fragmentation and degradation of primary forests are serious threats to the long-term persistence not only of the tree species they comprise, but also of many organisms inhabiting them. The Canarian laurel forest, known as monteverde, is a highly threatened endemic forest of the Macaronesian region. Lichens are considered ideal bioindicators for assessing the effects of human disturbances on ecosystems and anticipating the response of other less sensitive organisms. However, no studies have used them as model organisms to analyze the conservation status of this primary forest in the Macaronesian region. In the present study, we analyzed several variables of the lichen biota of the Canarian laurel forest on the islands with the highest representation within this archipelago: La Gomera, La Palma, and Tenerife. We analyzed the species richness (and its relationship to island size with the real and potential vegetation areas of the laurel forest); the lichen diversity value, the number of shared and exclusive species on each of the islands as well as lichen functional traits as they have become important for evaluating the response of epiphytic lichens to environmental changes. The results indicate that there are signs of a potential extinction debt occurring in the diversity of epiphytic lichens in some areas. Furthermore, it has been observed that, despite the presence of some exclusive species on each island, the overall composition does not differ between them. Considering the functional traits of lichens, there are patterns that can provide information about the unique characteristics of the laurel forest of each of the studied islands.

Arsenic-flux dependence of surface morphology in InAs homoepitaxy

Surface morphology in molecular-beam epitaxy of InAs(001), (111)A, and (111)B has been studied using scanning tunneling microscopy. The surface morphologies of InAs strongly depend on substrate temperature, substrate orientation, and As/In flux ratio. The size and density of two-dimensional InAs islands on the (001) surface decreases and increases, respectively, as the As/In flux ratio is increased. On the other hand, island size (density) is increased (decreased) with the increase in As flux on (111)A and (111)B surfaces. Surface reconstructions on growing surfaces strongly affect the diffusion and incorporation kinetics of In atoms, thereby resulting in the observed surface morphologies.

Electron transport barrier and high confinement in configurations with internal islands close to the plasma edge of W7-X

Abstract The low magnetic shear in the Wendelstein 7-X (W7-X) stellarator makes it feasible to shape the separatrix by the large islands constituting an island-divertor, and this can be exploited to access various magnetic configurations, including samples of different internal island sizes and locations. To investigate the configuration effects on the plasma confinement, a configuration scan was performed by changing the coil currents to vary the rotational transform between values 5 / 4 and 5 / 6 at the plasma boundary with different power levels (2, 4, 6 MW) of electron cyclotron resonance heating (ECRH) at a maximum plasma density of 8 × 10 19 m − 2 . neutral beam injection (NBI) heating was also applied during some configurations of the scan to create a density ramp and access high densities beyond the X2 ECRH cutoff. For the magnetic configurations, where the 5 / 5 and 5 / 6 island chains were moved closer to separatrix but remaining inside the last closed flux surface, the electron cyclotron emission shows that an electron temperature, T e , pedestal develops already during ECRH heated plasma buildup phase indicating a transport barrier, and the barrier sustains irrespective of changed plasma heating conditions such as NBI in the later part of discharge. The transport barrier is broken by subsequent fast crashes, observed with multiple plasma diagnostics with characteristics such as tokamak edge localized modes, and the corresponding crash amplitude and frequency vary with plasma pressure. The impact of the transport barrier on plasma confinement can be seen through the increased core T e profile, which could be responsible for the overall increase in the stored diamagnetic energy by approximately 10% for these configurations. After the plasma heating is terminated, a backwards transition to a degraded confinement state is also observed. These observations indicate a configuration triggered high confinement mode in low shear W7-X. This work focuses on the occurrence of this transport barrier for different magnetic configurations and its relation to internal magnetic islands.

The diversity of ants in moderately isolated islands of Japan: towards understanding of factors affecting their colonisation success

ABSTRACT How species diversity is determined is an old question in community ecology but is not yet well understood. Island biotas offer opportunities to address this issue. Here, the ant fauna was studied in five moderately isolated islands of Japan and compared with those in reference regions on the nearby main islands to assess whether ants’ ecological characteristics affect their island colonisation success. Species that were more abundant in the reference regions were more frequently found on the islands, suggesting that ant communities on these islands are likely to have a nested subset structure. Species inhabiting both forests and open lands tended to occur more frequently in the study islands at least than those exclusively inhabiting forests, but this difference was not significant. In addition, nest sites and worker body size did not have significant effects on their occurrence in these islands. These results seem to suggest that the study islands as a whole offer various environments that support a variety of ant species with different ecological characteristics. It is suggested in this study that island size affects the species richness, as has often been reported.

Evaluating the importance of footloose-type failure in ice island deterioration modeling

The drift and deterioration of large and tabular icebergs, also known as “ice islands” in the Arctic, are modeled for both operational (e.g., offshore risk mitigation) and research (e.g., oceanographic impact of melt water input) purposes. In this paper, we build a theoretical argument to show that the lateral deterioration of ice islands is controlled by the rate of sidewall notch growth at the waterline, with this growth leading to the development of underwater rams and buoyancy-induced calving via the ‘footloose’ mechanism. This dominance of footloose-type lateral deterioration allows for the majority of ice island deterioration to be simulated with only three oceanic variables: wave height, wave period, and sea-surface temperature. Information regarding the size and lineage of ice islands tracked in the Canadian Ice Island Drift, Deterioration and Detection (CI2D3) Database provides opportunity to assess our theoretical work, as the database serves as a validation dataset for simulations of ice island length and area change. When simulating the length reduction over time of ice islands tracked in the CI2D3 Database, the footloose model reduced the mean error over 80 d to +277 m, compared to −1545 and −1403 m with no-melt and thermal-melt models, respectively. We also demonstrate a new approach to simulating the areal deterioration of ice islands resulting from discrete footloose calving events. The approach utilizes two parameters: the length-to-width ratio of the ice island (r) and the width of a footloose calving event relative to the ice island's length (K). With r = 1.6 and K = 0.8, the mean error in modeled area was close to zero after 20 d. A comparison of stresses associated with footloose events from a 1D-beam model and those simulated with 3D finite-element modeling showed that the 1D and 3D simulations produce broadly similar results. This supports our approaches and parameter assignments for simulating ice island length and area reduction from footloose calving. These approaches can now be incorporated into ice island deterioration models. The benefit of this incorporation will be greatest for those interested in research of longer-term impacts of ice island deterioration on ocean properties given the greater improvements to model error over periods of time that are longer than those that usually concern offshore ice management operations.

Island geologic connections: Reimagining Guernsey's spatial dynamics through land–sea–geologic relations, past and present

AbstractThis paper explores the resizing, reshaping and connectivity of islands by examining ongoing relations between land and sea in the context of the Channel Island of Guernsey. Ideas of materiality, temporality and vertical depth are employed to explore how contemporary tides and past sea‐level change impact island–island connections, and island–mainland connections between Guernsey and France. By focusing on the littoral zone as a space of encounter between land and sea, the paper explores some of the processes that challenge the notion of an island having fixed edges, emphasising the island's shape and size as always in flux. The paper then explores how tides alternatively reveal and hide material structures such as rocks and causeways, making the underwater scape temporally visible and differently accessible as an extension of land. It enables connections to be made and remade. This is demonstrated through the example of Guernsey and the tidal island of Lihou. The paper subsequently considers these ideas in the context of Quaternary sea‐level change. The land known as Guernsey alternated between literal island surrounded by water, and a steep‐sided plateau on the Normanno‐Breton plain, coinciding with interglacials and glacials. This connection is referred to as geologic. I argue that by acknowledging Guernsey's former visible connection with France, lack of contemporary visibility in the underwater scape does not render this a disconnection. Rather, the geologic, as further evidenced in the contemporary natural and built environment of Guernsey, continues through an underwater scape. It reappears in other Channal Islands and France, demonstrating ongoing connections at a land–sea–geologic interface. The paper argues for geology as a form of vertical depth. It calls for greater consideration of the geologic in the human geographical study of islands.

Multiphase superconductivity at the interface between ultrathin FeTe islands and Bi2Te3

FeTe monolayer islands situated on a topological insulator Bi2Te3 (0001) surface were recently reported to exhibit the opening of an energy gap below temperatures T ~ 6 K, which could be due to a superconducting phase transition. In this work, we present a magnetic field dependent transport study proving that this gap is indeed of superconducting origin. Upon cooling, several drops in resistance are observed in the temperature range between 6 K and 2 K, indicating multiple transitions. Using the Ginzburg-Landau theory, we show that the critical magnetic field of the dominant high-temperature transition at ~ 6 K is governed by orbital Cooper pair breaking in larger FeTe islands, large enough to exceed the superconductive coherence length ξ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\xi$$\\end{document}. At smaller island sizes, transitions at lower temperatures < 6 K become more prominent, showing significantly increased critical fields dominated by paramagnetic pair breaking. The multiphase superconducting behaviour is in line with an observed wide distribution of FeTe islands width 5–100 nm and seems to reflect disorder effects at the interface to Bi2Te3. The proof of local superconductivity makes the FeTe interface to the topological insulator Bi2Te3 substrate a potential host of topological superconductivity.

Formation and coarsening of epitaxially-supported metal nanoclusters

This mini-review describes developments over the last ∼30 years in characterizing the nucleation & growth of epitaxially-supported metal nanoclusters (NCs) or islands during vapor deposition, as well as their post-deposition coarsening. A beyond-mean-field treatment for homogeneous nucleation & growth corrects the deficiencies of traditional treatments in describing, e.g., the island size distribution, but also necessitates consideration of the spatial distribution of islands and their capture zones. We discuss advances in modeling capabilities, including those based upon on an ab-initio level treatment of periphery diffusion kinetics, for description of the non-equilibrium growth shapes of these NCs, focusing on 2D NCs. For post-deposition coarsening of arrays of NCs, there is generally a competition between Ostwald Ripening (OR) and Smoluchowski Ripening (SR). SR is also known as Particle Migration & Coalescence. For 2D NCs in homoepitaxial systems, conventional OR is observed on pristine fcc(111) surfaces, dramatically enhanced OR in the presence of even trace amounts of chalcogens for Cu(111) and Ag(111), and anomalous OR on anisotropic fcc(110) surfaces. The unexpected discovery of SR for fcc(100) homoepitaxial systems prompted extensive analysis of the underlying diffusivities of 2D NCs as a function of size, as well as of NC coalescence dynamics. A comprehensive understanding of these processes is now available. Self-assembly of 3D NCs during deposition, issues related to heterogeneous nucleation, directed assembly, NC growth structure selection, and coarsening are addressed. For SR of 3D epitaxial NCs, recent insights into the size-dependence of diffusivity are described.

Low-intensity urbanisation alters community composition across multiple trophic levels on Lipsi Island, Greece.

Urbanisation has reduced the abundance and diversity of many taxonomic groups, and the effects may be more pronounced on islands, which have a smaller regional species pool to compensate. Green spaces within urban environments may help to safeguard wildlife assemblages, and the associated habitat heterogeneity can even increase species diversity. Here, total abundance and species diversity of butterflies, birds, and vegetation at nine rural and nine urban locations were quantified on Lipsi Island, Greece. Sites were assessed using Pollard walks for butterflies, point-count surveys for birds, and quadrats for vegetation. There was no significant difference in the abundance or species diversity of butterflies or vegetation among rural and urban locations, which could pertain to the low building density within urbanised areas and the minimal extent of urbanisation on the island. However, urban areas hosted a significantly greater abundance, richness, and diversity of birds compared to rural sites. The community composition of butterflies, birds, and vegetation also differed significantly between urban and rural locations, highlighting the impact of urbanisation on species across a broad range of trophic groups. This study contributes to ecological knowledge on the impacts of urbanisation across multiple trophic levels in island ecosystems, with comparisons across a gradient of island size and urbanisation intensity needed in future research.

The herpetofauna of the Sporades Islands (Aegean Sea, Greece): New discoveries and a review of a century of research

The Sporades are one of the most biologically important archipelagos in the Aegean Sea (Greece) and have received priority conservation over the last 50 years. However, despite numerous early efforts, its herpetofauna is only partially described, resulting in many distributional gaps that have prevented adequate understanding and management of the resident species communities. We review one century of bibliography from the Northern Sporades and combine this information with a review of museum specimens and insights from numerous extensive field surveys over the last near-decade to provide for the first time a comprehensive picture of the reptiles and amphibians of the archipelago. We report here on 26 new island records and find that the herptile communities of the region are largely derived from the herpetofauna of the nearby Thessaly mainland, with only a few introduced taxa. There is also a small but significant set of endemic taxa in the archipelago. Island species richness declines with decreasing island size and increasing duration of island isolation. Herptile communities on smaller islands are progressively nested subsets of the communities on larger islands. The presence of reptile species depends sensitively on the condition and management of native ecosystems. While non-aquatic species maintain largely healthy populations, most populations are under pressure from the combined effects of rampant tourist development, the destruction and degradation of rare wetland habitats, and the abandonment of traditional agricultural landscapes. We provide recommendations regarding sustainable management of the local reptile and amphibian populations.

Analysis of Runs of Homozygosity in Aberdeen Angus Cattle.

A large number of cattle breeds have marked phenotypic differences. They are valuable models for studying genome evolution. ROH analysis can facilitate the discovery of genomic regions that may explain phenotypic differences between breeds affecting traits of economic importance. This paper investigates genome-wide ROH of 189 Aberdeen Angus bulls using the Illumina Bovine GGP HD Beadchip150K to structurally and functionally annotate genes located within or in close ROH of the Aberdeen Angus cattle genome. The method of sequential SNP detection was used to determine the ROH. Based on this parameter, two ROH classes were allocated. The total length of all ROH islands was 11,493 Mb. As a result of studying the genomic architecture of the experimental population of Aberdeen Angus bulls, nine ROH islands and 255 SNPs were identified. Thirteen of these overlapped with regions bearing 'selection imprints' previously identified in other breeds of cattle, and five of these regions were identified in other Aberdeen Angus populations. The total length of the ROH islands was 11,493 Mb. The size of individual islands ranged from 0.038 to 1.812 Mb. Structural annotation showed the presence of 87 genes within the identified ROH islets.

Decadal timescale evolution of coral islands: insights from Lakshadweep Archipelago

Low–lying coral islands are susceptible to rising sea levels and climate change, posing risks to island habitability over the next century. The decadal timescale evolution of the islands can provide an understanding of the governing controls of change and island response. This study investigates variations in the shoreline morphology of the Lakshadweep coral islands (Northern Indian Ocean/Arabian Sea) using satellite datasets (2003–2022; CNES/Airbus;0.3m – 0.7m resolution) and sedimentological data. Of the thirty islands (ten inhabited), six islands (Bangaram, Thinnakara, Suheli, Minicoy, Androth and Bitra) have been studied. Most of these islands are less than 1 km2 in size except Androth and Minicoy (&amp;gt;4 km2). While the data is discontinuous for the islands due to cloud obscuring, the shoreline morphology depicts variations for all the islands’ studied, irrespective of habitation and size. Larger islands have undergone consistent erosion since 2007 (total land loss is approximately 3 - 5% cumulatively). Smaller islands have undergone lateral migration, with sediment erosion usually along the southern edge and sediment migration and accumulation northwards, however, overall, their size remains consistently stable. The migration of sediments is observed only from 2007–2017, which coincides with severe El–Nino Southern Oscillation (ENSO) and low amplitude positive Indian Ocean Dipole (IOD) events. Furthermore, sedimentological analysis along Bangaram’s (small island) accreting margin reveals unconsolidated bio-detrital grainstones with predominant sand-sized fractions (2 – 0.25mm). Corals (43%), molluscs (33%), forams (13%), and algae (8%) are the major sediment producers (with 3% unidentified bioclasts). The ongoing climate warming and ocean acidification will influence the carbonate sediment budget in addition to the changing hydrodynamics owing to monsoons, cyclones, and coupled ocean-atmospheric regional phenomenon, altering the sediment production, transport and accumulation on these islands. Furthermore, rising sea levels and consequent erosion by wave action might lead to rapid drowning in the next few centuries. Our study identifies the current status of the island size variability in the Lakshadweep Archipelago and how site-specific and global factors influence them, thus providing insights into assessing the habitability within these low-lying coral islands.

Analysis of the evolution of terrestrial relief through inverse elevation transition

Through an examination of the Theory of Seismic Energy and the Theory of Volcanic Energy, we come to comprehend that the interplay of internal and external energies in conducive terrain has led to immeasurable transformations, assessable within geological time frames. Consequently, this study posits that the intricate evolution of Earth's crust relief stems from the inverse shift in elevations and the mobility of oceanic water masses. This, in turn, influences the location, size, shape, and quantity of continents, islands, and oceans. It is crucial to recognize that the geographical features we currently observe merely capture a momentary snapshot, due to the constant movement of the Earth's surface.

Island area and diet predict diversity and distribution of bats in a Pacific Northwest archipelago

Abstract The island biogeography theory predicts that species richness in islands and island-like systems is the ultimate result of island isolation and area. Species with high dispersal capabilities are predicted to be less affected by these factors because of their capacity to move more efficiently between islands or habitats, and here we test this idea in bats, the only mammals capable of flight. We conducted mist net and acoustic surveys across 21 islands in the San Juan Archipelago (Washington State, United States) and adjacent northwest mainland to: (i) investigate the effects of island area, distance from mainland, and habitat on bat diversity; and (ii) evaluate whether differences in morphological (body mass, forearm length, wing loading) and ecological (dietary niche breadth, foraging guild) traits among species influence their prevalence across islands. We found that island size strongly influenced patterns of species richness, with larger islands having a greater number of bat species. However, neither island distance from mainland nor any measure of habitat availability was a significant predictor of species richness at the scale of this study. Additionally, we found that dietary niche breadth, as opposed to any morphological trait, best predicted the prevalence of species across the islands. Our results suggest that species with more specialized diets may be more vulnerable to habitat fragmentation, and provide insight into how geographic and ecological factors affect the diversity of insular bat communities, adding to growing knowledge about the role of species traits as mediators of their responses to large-scale landscape structure.

Epitaxial Growth of Nano‐Sized Pb Islands on SrTiO3 Substrate: Competition Between Electron Correlation and Enhanced Superconductivity

AbstractThe discovery of the interface‐enhanced superconductivity in the single‐layer film of FeSe epitaxially grown on SrTiO3 substrates has triggered a flurry of activity in the field of superconductivity. It raised the hope to find more conventional high transition temperature (Tc) superconductors that are purely driven by the electron‐phonon interaction at ambient pressure. Here the epitaxial growth of the Pb nano‐sized islands on SrTiO3 (001) substrates with the island volumes ranging from 286 to 4945 nm3 is reported by molecular beam epitaxy, followed by systematic scanning tunneling microscopic/spectroscopic (STM/S) investigation. The observed STS gap for the nanoscale islands highly dependent on the volumes of nano‐sized islands, can be divided into three regions. By performing a detailed spectroscopic investigation, it is founded that superconductivity in the volume above 3700 nm3 (Region I) has a zero temperature energy gap (Δ(0)) and Tc of 6.8 meV and 9.8 K obtained by BCS fitting, showing the largely‐enhanced Δ and slightly‐increased Tc by comparing to the bulk Pb (1.4 meV and 7.2 K). As the volume in the range from 1300 to 3700 nm3 (Region II), a large Coulomb gap induced by electron correlation emerged and shows a volume‐dependent behavior, suggesting the reduced size can enhance electron correlation in Pb islands. As the volume decreases down to Region III, enhanced electron correlation and Coulomb gap become more dominant and superconductivity is totally suppressed. The experiment reveals that an electron‐electron interaction in nano‐sized Pb islands can be significantly enhanced by reducing the island sizes and suppresses the superconductivity, thus demonstrates a competition between superconductivity and electron correlation as the volume varies.