Island Boundaries Research Articles

SPATIAL TEMPORAL ANALYSIS OF LAND SURFACE TEMPERATURE CHANGES IN AMBON ISLAND FROM LANDSAT 8 IMAGE DATA USING GEOGLE EARTH ENGINE

This study aims to analyze land surface temperature changes on Ambon Island using Landsat 8 imagery data and Google Earth Engine. The research method involves the use of Ambon Island boundary data from the Geospatial Information Agency (BIG) as well as Landsat 8 Collection 2 Tier 1 and Real-Time satellite image data that have been calibrated to reflect the reflectance of the Earth's surface to the atmosphere. The analysis steps include temperature conversion from Kelvin to Celsius, land surface temperature classification, and data export to Arc GIS software. The results showed an increase in land surface temperature associated with urban development in Ambon City, highlighting the importance of sustainable urban planning and good resource management to mitigate the negative impacts of land surface temperature increase and support adaptation to climate change. Keywords: Ambon Island, Geogle Earth Engine, Land Surface Temperature

Absence of Clausal Islands in Shupamem

Decades-long research on islands has led to the conclusion that island constraints are candidates for language universals. A recent surge in research on islandhood in African languages has revealed some would-be island configurations that are transparent for A¯- dependency formation. In this article, we show that in Shupamem, all clausal configurations expected to have the status of opaque island domains fail to block the formation of long-distance A¯- dependencies involving object ex situ focus. In support of the claim that A¯- movement has occurred in such cases, we rely on evidence from three wh- movement diagnostics (weak crossover effects, reconstruction phenomena and quantifier float). Furthermore, we show that non-movement dependencies across purported island boundaries in the language are also possible through the licensing of “island”-internal negative concord items by external non-local negators. We conclude that clausal island effects fail to materialize in Shupamem ex situ focus constructions and negative concord item-licensing domains. Based on an exploratory typological survey of islands in African languages, we indicate a trend toward varying degrees of island permeability in the area, concluding that while Shupamem is not an isolated example, it features one of the most permissive grammars known to date in this respect.

SAT432 Interactions Of Endocrine-disrupting Chemical (EDC) Exposure And Fear Recall On Small Noncoding RNA (sncRNA) Contents Of Rat Caput Extracellular Vesicles

Abstract Disclosure: R. Gillette: None. M. Aguirre: None. K. Bell: None. Y. Nadeem: None. L. Thompson: None. A.C. Gore: None. Extracellular vesicles (EVs) transfer a complex repertoire of small non-coding RNAs (sncRNA) to sperm as they transit the caput of the epididymis. These molecules are essential for the functional competence of sperm and are directly influenced by environmental factors such as stress, diet, and drug use. We hypothesized that prenatal exposure to EDCs would alter the sncRNA contents of caput extracellular vesicles, and that an exposure to a previously established contextual fear cue would exacerbate this effect. Pregnant dams were fed Nilla Wafers with either 3% DMSO (vehicle control) or Aroclor 1221 (1 mg/kg; a weakly estrogenic EDC) from embryonic day (E)8 until E18 and post-natal day (PND)1 to P21. In adulthood male rat offspring were subjected to a contextual fear conditioning paradigm in which each rat was exposed to an odorant paired with a shock (four 500 ms shocks at 0.7 mA) for three consecutive days. Two weeks later, all rats were returned to the conditioning chambers and exposed to the odorant for 5 minutes (no shocks). The next day, male rats were euthanized and the epididymis was dissected. EVs and total RNA isolated from the caput portion were sequenced on a NovaSeq 6000 SP in a single-end 75 bp format. Reads were checked for quality, trimmed for adapter sequences, aligned to the rat genome, and assigned an annotation designation across 10 different categories of sncRNA. We found that the majority of caput EV sncRNA were either tRNA fragments or piRNA and that unlike mice, miRNA accounted for a small portion of the total reads. The third largest category of aligned reads was in intergenic space and not associated with canonical small non-coding (snc) RNA loci. In-depth investigation determined these reads (∼19 nt) aligned strictly within the boundaries of known CpG islands (CpGi), which have not previously been reported to express any form of sncRNA. Re-exposure to a fear-associated scent 24 hours prior to sample collection substantially reduced the proportion tRNAs in EVs, which were supplanted by an increase in piRNA, CpGi sRNA, and lncRNA. This effect was exacerbated by prenatal EDC exposure and was particularly prevalent in the lncRNA and CpGi sRNA categories. Taken together our data show that the small RNA contents of caput epididymosomes of male rats is substantially different from previous observations reported in mice. We demonstrate that exposure to a contextual fear cue is a powerful influence on sncRNA composition of caput extracellular vesicles and that it is uniquely altered by prenatal EDC exposure. Finally, we provide evidence for what we believe may be a novel category of sncRNA. Presentation: Saturday, June 17, 2023

Probing the charge state of threading dislocations in indium nitride through advanced atomic force microscopy

Indium nitride (InN) plays an imperative role in continuing the success of III-nitride technology and extending its footprint into new application fields. However, the development of InN-based devices is hindered by the unusually high residual electron concentration in unintentionally-doped InN, whose origin remains unresolved. In this work, pits are observed at regions around the InN island boundaries, which are assigned to threading dislocations (TDs). Since the surface band bending of InN is found to be intrinsically downward, the positive currents detected exclusively at the InN island boundary regions upon applying positive sample bias are leakage currents. This further points to the presence of TDs in these regions, which can act as localized conductive leakage paths. Interestingly, the surface potentials at the InN island boundary regions are found to be 35–45 mV more positive compared to the InN islands. This can be attributed to the presence of positively charged TDs due to the formation of donor-type point defects along their dislocation cores. Hence, TDs in InN can donate electrons and serve as one of the factors contributing to its high n-type conductivity.

Integrative systematics and conservation of endangered Carabus nankotaizanus (Coleoptera: Carabidae) in Taiwan

Abstract The endangered endemic ground beetle, Carabus nankotaizanus Kano, 1932 (Coleoptera: Carabidae), consists of 4 subspecies distributed across the lowlands to mountain forests of Taiwan. However, continuous morphological variation among the subspecies and large altitudinal range gaps between lowland and mountain populations of C. nankotaizanus raise questions concerning its species boundaries. We assessed the species boundaries between lowland and mountain populations of C. nankotaizanus using an integrative approach combining morphological, molecular, life-history, and ecological traits. Future suitable habitats were predicted using ecological niche models to evaluate the effect of range shifts driven by climate warming. The analyses of morphological and ecological traits indicate that the lowland and mountain populations of C. nankotaizanus are 2 distinct phenetic and ecological species. The molecular phylogeny further supported 4 divergent groups (paraphyletic C. nankotaizanus sp. 1 of the northern lowland + monophyletic C. nankotaizanus sp. 2 of the northern mountain, paraphyletic C. nankotaizanus sp. 3 of the southeastern lowland + monophyletic C. nankotaizanus sp. 4 of the mountain groups). We recommend the designation of the 4 cryptic C. nankotaizanus as candidate species and officially protected evolutionary lineages. Future range shifts of C. nankotaizanus sp. 1 to higher latitudinal lowlands of northern Taiwan may pose significant challenges to its conservation due to urban development and island boundary. By contrast, upcoming range shifts of the mountain C. nankotaizanus species to higher altitudes of protected national parks and forest reserves in the Central Mountain Range may not represent a major threat to its survival.

Page curve and island in EGB gravity

In this paper, the information paradox on lower-dimensional Gauss–Bonnet gravity, known as a three-dimensional EGB black hole, is studied using the quantum extremal island approach. For that, we connect an auxiliary flat bath system to this timelike singularity spacetime and estimate the entropy of hawking radiation in its asymptotic regions when gravity is weak. The addition of island areas to the entanglement wedge of radiation causes its entropy to obey the Page curve, as shown. The quantum extremal surface, or island boundary, is outside the horizon. This yields a time-independent equation for Hawking radiation fine-grained entropy compatible with the appropriate Page curve. We also discover the modifications to this entropy and Page time.

Self-generated vortex flows in a tokamak magnetic island with a background flow

We present a gyrokinetic theory of self-generated E × B vortex flows in a magnetic island in a collisionless tokamak plasma with a background vortex flow. We find that the long-term evolution of the self-generated vortex flows can be classified into two regimes by the background vortex flow potential Φ, with an asymptotic criterion given by , where T is temperature, ε is the inverse aspect ratio and r is the radial coordinate. We find that the background vortex flow above the criterion significantly weakens the toroidal precession-induced long-term damping and structure change of the self-generated vortex flows. That is, the finite background vortex flow is beneficial to maintain the self-generated vortex flows, favorable to an internal transport barrier formation. Our result indicates that the island boundary region is a prominent location for triggering the transition to an enhanced confinement state of the magnetic island.

Quality Assessment of Global Ocean Island Datasets

Ocean Island data are essential to the conservation and management of islands and coastal ecosystems, and have also been adopted by the United Nations as a sustainable development goal (SDG 14). Currently, two categories of island datasets, i.e., global shoreline vector (GSV) and OpenStreetMap (OSM), are freely available on a global scale. However, few studies have focused on accessing and comparing the data quality of these two datasets, which is the main purpose of our study. Specifically, these two datasets were accessed using four 100 × 100 (km2) study areas, in terms of three aspects of measures, i.e., accuracy (including overall accuracy (OA), precision, recall and F1), completeness (including area completeness and count completeness) and shape complexity. The results showed that: (1) Both the two datasets perform well in terms of the OA (98% or above) and F1 (0.9 or above); the OSM dataset performs better in terms of precision, but the GSV dataset performs better in terms of recall. (2) The area completeness is almost 100%, but the count completeness is much higher than 100%, indicating the total areas of the two datasets are almost the same, but there are many more islands in the OSM dataset. (3) In most cases, the fractal dimension of the OSM dataset is relatively larger than the GSV dataset in terms of the shape complexity, indicating that the OSM dataset has more detail in terms of the island boundary or coastline. We concluded that both of the datasets (GSV and OSM) are effective for island mapping, but the OSM dataset can identify more small islands and has more detail.

Investigating the corrosion resistance of Cu-doped Ni-Mo low alloy steel through electrochemical tests

Corrosion resistance of Cu-doped Ni-Mo low alloy steel (Ni-Mo steel) in marine environments was systematically investigated through microstructure observation and galvanostatic polarization tests. Results show that solid solution Cu improved the corrosion thermodynamic stability of steel. The increasing Cu content promoted the formation of Cu-rich precipitates, martensite-austenite island, granular bainitic and high angle grain boundary, increasing the surface potential difference and the occurrence probability of local galvanic corrosion on steel surface. The addition of Cu improved the protectiveness of corrosion product film after galvanostatic polarization tests relying on the functions of CuFeO2 and CuO, whose formation was mainly related to the solid solution Cu in Ni-Mo steel.

Invariant regions in piecewise linear area-preserving map

This paper studies regular islands (invariant regions) associated with elliptic periodic points of a piecewise linear area-preserving map. We reveal why regular island chains are interspersed in a chaotic sea, which is typical of the behavior exhibited by the area-preserving map. We find that regular islands may be ellipses or polygons and this depends on whether the rotation number of the rotation matrix that defines the linear map is irrational or rational. We also present a method for determining the boundary of these regular islands and chaotic seas (the largest invariant set). We show that critical lines play an important role in determining the boundaries of regular islands and chaotic seas.

Antiferromagnetism-driven two-dimensional topological nodal-point superconductivity

Magnet/superconductor hybrids (MSHs) hold the promise to host emergent topological superconducting phases. Both one-dimensional (1D) and two-dimensional (2D) magnetic systems in proximity to s-wave superconductors have shown evidence of gapped topological superconductivity with zero-energy end states and chiral edge modes. Recently, it was proposed that the bulk transition-metal dichalcogenide 4Hb-TaS2 is a gapless topological nodal-point superconductor (TNPSC). However, there has been no experimental realization of a TNPSC in a MSH system yet. Here we present the discovery of TNPSC in antiferromagnetic (AFM) monolayers on top of an s-wave superconductor. Our calculations show that the topological phase is driven by the AFM order, resulting in the emergence of a gapless time-reversal invariant topological superconducting state. Using low-temperature scanning tunneling microscopy we observe a low-energy edge mode, which separates the topological phase from the trivial one, at the boundaries of antiferromagnetic islands. As predicted by the calculations, we find that the relative spectral weight of the edge mode depends on the edge’s atomic configuration. Our results establish the combination of antiferromagnetism and superconductivity as a novel route to design 2D topological quantum phases.

Effects of Scanning Strategy on the Densification and Microhardness of Selective Laser Melting Mg–Y–Sm–Zn–Zr Alloy

Herein, Mg–Y–Sm–Zn–Zr alloy samples are prepared using selective laser melting (SLM). The effect of the scanning strategy on pore defects and microhardness is investigated. Pore defects are classified into lack of fusion (LOF) defects, gas pore (GP) and keyhole (KH) defects, and irregular pore (IRP) defects according to lengths and roundness. The LOF defect is caused by powder accumulation, spheroidization, droplet solidification preferentially, and pore defects accumulation. The recoil pressure causes the GP and KH defect, and different remelting zones affect its release. The filling behavior of LOF defects at different layer rotation angles and the connection of GPs and KH defects will form IRP defects. The microhardness test shows that the average microhardness is inversely proportional to porosity. The island size of 4 × 4 mm eases the accumulation of powder at the island boundaries, prevents spheroidization, and facilitates adequate spreading of droplets. The layer rotation angle of 67° inhibits the accumulation of pore defects and facilitates the filling of pore defects. The sample with the maximum densification (98.53%) and the highest average microhardness value (95.64 HV) is obtained under this scanning strategy.

Minimal Controlled Islanding With Similarity-Based Coherency Identification Using Phasor Measurement Data

Controlled islanding is the last protective scheme to prevent passive islanding or total system blackout caused by cascading failures. In this article, a novel coherency detection approach is proposed, which is based on a density and distance clustering algorithm. The coherency detection approach is parameter free and requires only the frequency measurement data since the approach utilizes the cosine similarity combined by the Gaussian principle. Following the coherency detection, the proposed island reduction algorithm utilizes frequency deviation at center-of-inertia reference and locates the fault-affected generators plus the faulted area to construct the islanding scenarios. To find a practical splitting strategy with better network reconnection, an island reduction algorithm is presented to reduce the number of islands and isolate the faulted area from the rest of the system considering the coherency and system operational constraints. Additionally, an mixed integer liner programming (MILP) optimization model based on the linearized ac power flow is employed to find the optimal island boundaries and guarantee the efficient isolation of critical or most affected islands. The efficiency and performance of the proposed islanding approach are tested on the IEEE 118-bus test system.

Cosmologies, singularities and quantum extremal surfaces

Following [1], we study quantum extremal surfaces in various families of cosmologies with Big-Crunch singularities, by extremizing the generalized entropy in 2-dimensional backgrounds which can be thought of as arising from dimensional reduction. Focussing first on the isotropic AdS Kasner case, introducing a spatial regulator enables relating the locations in time of the quantum extremal surface and the observer. This shows that the quantum extremal surface lags behind the observer location. A potential island-like region, upon analysing more closely near the island boundary, turns out to be inconsistent. Similar results arise for other holographic cosmologies. We then study certain families of null Kasner singularities where we find that the quantum extremal surface can reach the near singularity region although the on-shell generalized entropy is generically singular. We also study other cosmologies including de Sitter (Poincare slicing) and FRW cosmologies under certain conditions.

Unpredictability in Hamiltonian systems with a hierarchical phase space

One of the main consequences of the complex hierarchical structure of chaotic regions and stability islands in the phase space of a typical nonlinear Hamiltonian system is the phenomenon of stickiness. The chaotic orbits that approach an island are trapped in its neighborhood for arbitrarily long times, in which the orbits behave similarly as quasiperiodic orbits. In this paper, we characterize the boundary between chaos and regular motion in the phase space of the standard map for distinct parameter values. The orbits are distinguished between regular and chaotic employing a recently proposed method of weighted Birkhoff averages. We quantify the dimension of the boundaries of the islands using the uncertainty exponent. In our simulations, we show that the dimension of the island's boundary depends on the scale of the initial condition uncertainty and the level of the hierarchical structure. We also show that the trapping in the vicinity of the islands causes an obstruction in the predictability of the final state of an orbit. We present how this loss of predictability results in larger dimensions at the inner levels of the islands.

Topographic Influences on the Wind-Driven Exchange between Marginal Seas and the Open Ocean

AbstractThe wind-driven exchange through complex ridges and islands between marginal seas and the open ocean is studied using both numerical and analytical models. The models are forced by a steady, spatially uniform northward wind stress intended to represent the large-scale, low-frequency wind patterns typical of the seasonal monsoons in the western Pacific Ocean. There is an eastward surface Ekman transport out of the marginal sea and westward geostrophic inflows into the marginal sea. The interaction between the Ekman transport and an island chain produces strong baroclinic flows along the island boundaries with a vertical depth that scales with the ratio of the inertial boundary layer thickness to the baroclinic deformation radius. The throughflows in the gaps are characterized by maximum transport in the center gap and decreasing transports toward the southern and northern tips of the island chain. An extended island rule theory demonstrates that throughflows are determined by the collective balance between viscosity on the meridional boundaries and the eastern side boundary of the islands. The outflowing transport is balanced primarily by a shallow current that enters the marginal sea along its equatorward boundary. The islands can block some direct exchange and result in a wind-driven overturning cell within the marginal sea, but this is compensated for by eastward zonal jets around the southern and northern tips of the island chain. Topography in the form of a deep slope, a ridge, or shallow shelves around the islands alters the current pathways but ultimately is unable to limit the total wind-driven exchange between the marginal sea and the open ocean.

An algorithm for computing phase space structures in chemical reaction dynamics using Voronoi tessellation

An efficient sampling algorithm is proposed for computing reactive islands, which consist of intersections of reactive trajectories and a Poincaré surface of section (PSOS), and are characterized by the number of times the reactive trajectories intersect the PSOS before/after reactions take place. The boundaries of reactive islands are series of intersections of cylindrical stable and unstable invariant manifolds emanated from a normally hyperbolic invariant manifold located, typically, nearby a rank-one potential energy saddle, which forms “reactivity boundaries”. The reactive islands structures enable us to predict the fate of trajectories. The proposed algorithm estimates regions of reactive islands on the PSOS as a Voronoi diagram constructed from the set of labeled intersections of computed molecular dynamics trajectories. The algorithm iteratively refines the boundaries of the estimated reactive islands efficiently, by computing trajectories of which initial condition is sampled from the estimated boundaries of reactive islands in the Voronoi diagram of the previous iteration step. The efficiency of the proposed algorithm is scrutinized, compared with random sampling algorithm and using a two-degrees of freedom Hamiltonian system of a double well potential, and further possible extensions of the proposed algorithm are addressed.

Coalescence of islands in freely suspended smectic films

Smectic liquid crystal films a few molecular layers thick that are freely suspended in air are used as a model system to study the coalescence of fluids in two dimensions. High-speed video microscopy is used to observe the coalescence of islands, which are thicker, disk-shaped regions of the film, in a process driven by the line tension associated with edge dislocations along the island boundaries and limited by viscous dissipation in the liquid crystal and in the surrounding air. The early time growth of the bridge connecting the merging islands reveals much slower dynamics than predicted by Hopper's classical hydrodynamic model of coalescence of two infinitely long, fluid cylinders in vacuum, a discrepancy proposed to be due to significant dissipation in the background film and in the air that is not included in Hopper's theory. At late times, the elliptical merged island relaxes exponentially to a circular shape, at rates that are described quantitatively by a model originally developed for the evolution of fluid domains in Langmuir films.

Impact of magnetic islands on plasma flow and turbulence in W7-X

The effect of magnetic islands on plasma flow and turbulence has been experimentally investigated in the stellarator W7-X. Magnetic configurations with the 5/5 magnetic island positioned at the plasma edge, inside the last closed flux surface, are studied. The main diagnostic used in the present work is a V-band Doppler reflectometer that allows the measurement of the perpendicular plasma flow and density fluctuations with good spatial resolution. A characteristic signature of the 5/5 magnetic island is clearly detected in the perpendicular flow profile. The comparison of the experimental flow and the neoclassically driven E × B flow indicates that the island contribution to the flow is maximum at the island boundaries and close to zero at the island O-point. Besides, a reduction in the density fluctuation level is found nearby the island O-point. The similarities between these observations and those found in other devices and in gyrokinetic simulations are discussed.

Natural aging of Ni60Nb40 metallic glass thin film: Evolution of microstructure and mechanical properties

Since metallic glass thin films (MGTFs) are commonly used in the atmosphere of air, the study on the evolution of structure, morphology, and mechanical properties of MGTFs exposed to air is of great significance for the practical application of MGTFs. The oxide formation mechanisms are investigated by experimental and calculation methods in this work. The results indicated that the crystalline oxide NiNb2O6 can be formed when exposed to air. The crystal structure of the oxide is orthorhombic, and the lattice constants can be calculated as: a = 14.022, b = 5.675 and c = 5.015 nm. The oxide NiNb2O6 was initiated around the amorphous island-like boundary during natural aging. The island boundary of amorphous matrix can provide the formation condition of nucleation and growth for crystalline oxide. The averaged Young's modulus and hardness of NiNb2O6 oxide are much higher than that of the amorphous matrix based on the results of experiments and first-principle calculations, indicating that the presence of crystalline oxides might improve the wear-resistance performance of the films.