Distribution Of Islands Research Articles

Parallel Detection Based on a Generalized Partial Response Target for Staggered Bit-Patterned Media Recording Systems

We consider a prospective island distribution of bit-patterned media recording (BPMR) that consists of a hexagonal array called a staggered BPMR. Although the staggered BPMR can reduce two-dimensional interference, including intersymbol interference from the downtrack direction and intertrack interference from the cross-track direction, the structure of the staggered BPMR is unsuitable for the detection schemes of regular BPMR. In the staggered BPMR, the islands along the neighboring tracks are skewed by a half period from the islands on the main track. Consequently, an island on the main track is distorted by the four closest islands on the neighboring tracks and the two closest islands on the main track. To detect the main data, based on the generalized partial response target, we divided the interference into three parts and applied three one-dimensional detectors. Then, to estimate the original signal, we averaged the three outputs of the three detectors. The simulation results demonstrate that the proposed model improves performance compared with those described in previous studies.

Study of Niobium Mononitride Thin Films Grown Using High Power Impulse Magnetron Sputtering

Herein, the effect of microstructure on the electronic, and superconducting properties of niobium mononitride (NbN) thin films grown using a high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (dcMS) is studied. X‐ray reflectivity, cross‐sectional scanning electron microscopy and atomic force microscopy measurements suggest that the film grown with dcMS has a non‐uniform distribution of islands with loosely packed columns while the HiPIMS grown film has a smoother surface and a denser microstructure. Although the X‐ray diffraction measurements show a single‐phase rock‐salt‐type crystal structure in both cases, the local and electronic structure analyzed using N K‐edge X‐ray absorption near edge structure measurements reveals the evidence of a large amount of Nb vacancies in dcMS‐NbN while HiPIMS‐NbN film is closer to stoichiometry. The ordered structure of HiPIMS‐NbN sample results in a relatively higher superconducting transition temperature of 15.2 K and lower normal state resistivity of 90 μΩ cm with a moderate critical field of 18 T and smaller coherence length of 4.2 nm. These results suggest HiPIMS can be utilized to grow high‐quality superconducting thin films of few nanometers required in modern technological devices such as single‐photon detectors, superconducting quantum interference devices.

Statistical description of coalescing magnetic islands via magnetic reconnection

The physical picture of interacting magnetic islands provides a useful paradigm for certain plasma dynamics in a variety of physical environments, such as the solar corona, the heliosheath and the Earth's magnetosphere. In this work, we derive an island kinetic equation to describe the evolution of the island distribution function (in area and in flux of islands) subject to a collisional integral designed to account for the role of magnetic reconnection during island mergers. This equation is used to study the inverse transfer of magnetic energy through the coalescence of magnetic islands in two dimensions. We solve our island kinetic equation numerically for three different types of initial distribution: Dirac delta, Gaussian and power-law distributions. The time evolution of several key quantities is found to agree well with our analytical predictions: magnetic energy decays as$\tilde {t}^{-1}$, the number of islands decreases as$\tilde {t}^{-1}$and the averaged area of islands grows as$\tilde {t}$, where$\tilde {t}$is the time normalised to the characteristic reconnection time scale of islands. General properties of the distribution function and the magnetic energy spectrum are also studied. Finally, we discuss the underlying connection of our island-merger models to the (self-similar) decay of magnetohydrodynamic turbulence.

The influence of El Niño Southern Oscillation on urban heat island formation at tropical city: Case of Kuching City, Sarawak

El-Niño Southern Oscillation (ENSO) is an opposing natural climate phenomenon in which the El Niño event causes droughts and the La Niña event causes floods. Literature studies stated there is still a lack of studies on the application of remote sensing in studying the effect of ENSO on Urban Heat Island (UHI) distribution patterns. The effect of UHI amplifies temperature, especially during El Niño. The objective of this study is to examine the influence of ENSO on UHI formation in tropical cities on a local scale. This study uses MODIS data and Landsat satellite data from 1988 to 2019. This study uses a combination of both data to investigate the influence of ENSO on UHI formation. The data must undergo pre-processing before the digital number is converted to Land Surface Temperature (LST). This study found that La Niña and El Niño events influenced the pattern of UHI variation. The strength of El Niño and La Niña differences influenced the value of LST and the total UHI area with a temperature of 30 °C. The result discovered that during the El Niño event, the maximum, minimum and mean temperature values of LST were higher than during the La Niña event and the total of the area hot spots that have temperatures above 30 ºC is higher during El Niño than during La Niña. The result of the study is very important to the community, local governments, and urban planners because remote sensing provides spatial information that represents the hot spot and cold spot. Keywords: ENSO, UHI, remote sensing, spatial pattern.

Study on the spatial heterogeneity of urban heat islands and influencing factors

Conflicts between urban expansion and urban heat islands (UHIs) are increasing markedly, because of accelerated urbanization, and it is urgent to mitigate the UHI effect. In this study, we explored the spatial heterogeneity of UHIs from a neighborhood perspective via inversion of land surface temperature (LST) based on Landsat-8 remote sensing image data and using local Moran's I; the central urban area of Jinan City was selected as the study area. Furthermore, by constructing a system of urban spatial structure indicators and adopting methods such as correlation coefficient analysis and spatial econometric modeling, the factors influencing UHI were further revealed. The results showed that (1) There was spatial heterogeneity of the UHI in the central urban area of Jinan. The High-High cluster was mainly distributed in the north of the central urban area of Jinan; the Low-Low cluster was primarily distributed in the south of the central urban area of Jinan and the waters. Agglomeration distribution approximately coincided with heat island distribution. (2) The correlations between urban spatial structure indicators and LST in different dimensions were generally high and varied significantly. The two-dimensional and three-dimensional indicators all showed a highly significant positive relationship with LST. The mean and standard deviation of the DEM and absolute building height in the one-dimensional indicators were both negatively and significantly correlated with LST. (3) Building height standard deviation had a significantly positive spillover effect on the LST of the neighboring areas; this spillover effect was greater than the direct effect on these regions.

Computational characterization of domain-segregated 3D chromatin structure and segmented DNA methylation status in carcinogenesis.

The high‐order chromatin structure, together with DNA methylation and other epigenetic marks, plays a vital role in gene regulation and displays abnormal status in cancer cells. Theoretical analyses are expected to provide a more unified understanding of the multi‐omics data on the large variety of samples, and hopefully a common picture of carcinogenesis. In particular, we are interested in the question of whether an underlying origin DNA sequence exists for these epigenetic alterations. The human genome consists of two types of megabase‐sized domain based on the distribution of CpG islands (CGIs) that show distinct structural, epigenetic, and transcriptional properties: CGI‐rich and CGI‐poor domains. Through an integrated analysis of chromatin structure, DNA methylation, and RNA sequencing data, we found that, in carcinogenesis, the two different types of domain display different structural changes and have an increased number of DNA methylation differences and transcriptional‐level differences, compared with in noncancer cells. We also compared the structural features among carcinogenesis, senescence, and mitosis, showing the possible connection between chromatin structure and cell state, which could affect vital cancer‐related properties. In summary, chromatin structure, DNA methylation, and gene expression, as well as their changes observed in several types of cancers, show a dependence on multiscale DNA sequence heterogeneity.

Geographical isolation versus dispersal: Relictual alpine grasshoppers support a model of interglacial diversification with limited hybridization

Alpine biotas are paradigmatic of the countervailing roles of geographical isolation and dispersal during diversification. In temperate regions, repeated distributional shifts driven by Pleistocene climatic oscillations produced both recurrent pulses of population fragmentation and opportunities for gene flow during range expansions. Here, we test whether a model of divergence in isolation vs. with gene flow is more likely in the diversification of flightless alpine grasshoppers of the genus Podisma from the Iberian Peninsula. The answer to this question can also provide key insights about the pace of evolution. Specifically, if the data fit a divergence in isolation model, this suggests rapid evolution of reproductive isolation. Genomic data confirm a Pleistocene origin of the species complex, and multiple analytical approaches revealed limited asymmetric historical hybridization between two taxa. Genomic-based demographic reconstructions, spatial patterns of genetic structure and range shifts inferred from palaeodistribution modelling suggest severe range contraction accompanied by declines in effective population sizes during interglacials (i.e., contemporary populations confined to sky islands are relicts) and expansions during the coldest stages of the Pleistocene in each taxon. Although limited hybridization during secondary contact leads to phylogenetic uncertainty if gene flow is not accommodated when estimating evolutionary relationships, all species exhibit strong genetic cohesiveness. Our study lends support to the notion that the accumulation of incipient differences during periods of isolation were sufficient to lead to lineage persistence, but also that the demographic changes, dispersal constraints and spatial distribution of the sky islands themselves mediated species diversification in temperate alpine biotas.

Spatiotemporal Variations in Atmospheric Urban Heat Island Effects and Their Driving Factors in 84 Major Chinese Cities

Accelerating urbanization seriously intensifies urban heat island effects in China, which in turn affects regional environment and human health. However, the spatiotemporal patterns of atmospheric urban heat island effects remain poorly understood in China as previous research is mostly based on satellite-sensed radiation temperatures. Using long-term daily meteorological observations from 1960 to 2017, this study explored the geographical distribution of atmospheric urban heat islands over diurnal, intra-annual, and inter-annual timescales in 84 major cities in China. The results show that on average, the intensity of the urban heat island reaches(0.9±1.1)℃, although large geographical variations were detected. The intensity was, overall, larger in northern China than in southern China; North China showed the largest annual intensity of(1.4±1.4)℃, and seasonal intensity variations were high in northeast and northwest China. Here, significantly higher intensity effects were measured at night[(1.2±1.1)℃] than during the day[(0.5±1.2)℃], and in summer than winter during the day, and in winter than summer during the night. Inter-annually, the annual mean urban heat island effect has increased by an average of 0.040℃ per decade, although this trend weakens after 2009. Furthermore, we found that the spatial patterns of atmospheric heat island intensity was greatly affected by climatic background conditions and the location of meteorological stations, while the long-term trends were strongly influenced by the impervious surface area. This study improves understanding of the atmospheric urban heat island effect in China and provides important insights for formulating urban land-use strategies to alleviate high temperatures and heatwaves.

The influence of land use on the spatial distribution and intensity of heat islands in Slovenia

Heat islands (HI) are a common anthropogenic phenomenon and are defined as artificial surfaces (urban areas) that have a higher average temperature than their surroundings (rural areas). The aim of this work was to determine the influence of land use on the spatial distribution and intensity (HIi ) of HI in Slovenia. The MODIS Land Surface Temperature (LST) and Corine Land Cover (CLC) databases were used to perform the analysis. Within the identified HI, two HI levels were determined based on temperature difference. The results revealed a statistically significant negative correlation between HIi and both forest co%ver and forest fragmentation (forest edge density and ratio of mean forest patch size to HI size). Artificial surface was positively correlated with HIi . The results contribute to the understanding of the spatial distribution of HI and HIi and provide informati%on for spatial planning and policy-making to reduce the negative impact of HI.

Taxonomy with an absence of evidence results in unnecessary nomenclatural change: the case of Tetragonia trigyna Banks & Sol. ex Hook.f. (Aizoaceae) from New Zealand

ABSTRACT Tetragonia trigyna Banks & Sol. ex Hook.f. was the accepted name for a well-known coastal species in New Zealand from when it was formally named by J. D. Hooker in 1864 until the 1990s. In 1994, a Flora of Australia volume covering Norfolk and Lord Howe Islands reduced T. trigyna to synonymy of the Australian T. implexicoma (Miq.) Hook.f.. This was followed in 1999 by the first acceptance of T. implexicoma in New Zealand botanical literature when the name was used in a checklist of plant species from Aorangi Island, Poor Knights Islands. In a departure from what is generally considered accepted taxonomic practice, no empirical evidence or discussion of characters was provided in support of either decision. Subsequently, T. implexicoma has become widely used in New Zealand. The taxonomic study of T. implexicoma and T. trigyna reported here provides empirical data from herbarium specimens and cultivated plants, and concludes both species should be recognised. Tetragonia trigyna differs from T. implexicoma by its broader leaves, shorter pedicels, shorter tepals, and fewer and shorter stamens. Images in the citizen science iNaturalist platform confirm the diagnostic characters and distribution, and recently published nrDNA ITS sequence data distinguish both species. Accordingly, T. trigyna is reinstated with a distribution of New Zealand (including Chatham, Kermadec and Three Kings islands), Norfolk Island and Lord Howe Island, and T. implexicoma is considered restricted to continental Australia and Tasmania.

Growth temperature effect on physical and mechanical properties of nitrogen rich InN epilayers

A set of N-polar InN epilayers has been grown at different temperatures by plasma–assisted molecular beam epitaxy (PA-MBE) on GaN/AlN/Al2O3(0001) templates. The purpose is to understand how the variation of crucial factor, such as the temperature, impacts the growth process and the resulting samples’ properties. The characterization of these InN samples using atomic force microscopy and scanning electron microscopy showed different island distributions and shapes by varying the growth temperature. High resolution-X-ray diffraction (HRXRD) enabled to identify a single crystalline phase (hexagonal wurtzite), whatever the growth temperature. Actually, the increase of growth temperature up to 560 °C has improved the crystalline quality; whereas for high temperature, the crystalline quality degrades. The dislocation density of the epilayer grown at this optimum temperature (around 560 °C) is about 1.9 × 1010 cm−2, which is determined using HRXRD spectra analysis. High compressive residual stress value of 0.54 GPa was derived using Raman spectroscopy. Room temperature photoluminescence (PL) displays a band gap energy around 0.69 eV. Besides, Burstein-Moss effect, the PL band gap energy measured at 10 K is dictated by the biaxial compressive residual stresses. Nanoindentation tests were carried out on InN epilayers. Only, the sample grown at 560 °C exhibited a pop-in event, for which the measured hardness and Young’s modulus are of 4.5 ± 0.5 GPa and of 171 ± 8 GPa, respectively. Accordingly, the growth temperature of InN epilayers influences the resulting physical and mechanical performances, thus a good compromise between physical and mechanical features permits to manufacture efficient devices.

In situ radiation explains the frequency of dioecious palms on islands.

Dioecy has evolved up to 5000 times in angiosperms, despite the potentially high intrinsic costs to unisexuality. Dioecy prevents inbreeding, which is especially relevant on isolated islands when gene pools are small. Dioecy is also associated with certain dispersal traits, such as fruit size and type. However, the influence of dioecy on other life history traits and island distribution remains poorly understood. Here, we test the effect of dioecy on palm (Arecaceae) speciation rates, fruit size and frequency on islands. We used phylogenetic comparative methods to estimate the ancestral state of the sexual system and its impact on speciation rates and fruit size. Frequency of sexual systems, effect of insularity on the probability of being dioecious, and phylogenetic clustering of island dioecious vs. mainland species were inferred. Lastly, we determined the interplay of insularity and sexual system on speciation rates. Palms repeatedly evolved different sexual systems (dioecy, monoecy and polygamy) from a hermaphrodite origin. Differences in speciation rates and fruit size among the different sexual systems were not identified. An effect of islands on the probability of the palms being dioecious was also not found. However, we found a high frequency and phylogenetic clustering of dioecious palms on islands, which were not correlated with higher speciation rates. The high frequency and phylogenetic clustering may be the result of in situ radiation and suggest an 'island effect' for dioecious palms, which was not explained by differential speciation rates. This island effect also cannot be attributed to long-distance dispersal due to the lack of fruit size difference among sexual systems, and particularly because palm dispersal to islands is highly constrained by the interaction between the sizes of fruit and frugivores. Taken together, we suggest that trait flexibility in sexual system evolution and the in situ radiation of dioecious lineages are the underlying causes of the outstanding distribution of palms on islands.

Prevalence, population structure, distribution of serotypes, pilus islands and resistance genes among erythromycin-resistant colonizing and invasive Streptococcus agalactiae isolates recovered from pregnant and non-pregnant women in Isfahan, Iran

BackgroundThe information on antibiotic resistance and molecular features of Group B Streptococcus (GBS) are essential for epidemiological purposes as well as vaccine development. Therefore, we aimed to assess the antimicrobial resistance profiles and molecular characteristics of GBS isolates in Isfahan, Iran. A total number of 72 colonizing and invasive GBS were collected from pregnant and non-pregnant women. The GBS isolates were analyzed for resistance profiles, capsular genotyping, and detection of PI-1, PI-2a, PI-2b, hvgA, ermB, ermTR, lnuB and, mefA genes. Besides, erythromycin-resistant strains were subjected to multilocus sequence typing (MLST).ResultsThe prevalence of colonizing and invasive GBS were 11 and 0.05%, respectively. The frequency of capsular serotypes was as follows: III (26.3%), Ia (20.83%), Ib and V (each 15.2%), IV (9.7%), II (8.3%), VII (2.7%), and VI (1.3%). Overall frequencies of PIs were as follows: PI-1, 37.5%, PI-1 + PI-2a, 30.5%, PI-1 + PI-2b, 29.1% and PI-2b, 2.7%. Two maternal colonizing GBS (2.6%) were hvgA positive and were belonged to ST-17/CPS-III/PI-1 + PI-2b lineage. Among 30(41.6%) erythromycin resistant GBS, 21 isolates (70%) harbored ermB gene, followed by ermTR (23.3%) and mefA (10%). One clindamycin-resistant isolate harbored the lnuB gene. MLST analysis revealed the following five clonal complexes (CCs) and nine STs: (CC-19/ST-335, ST-19, and ST-197), (CC-12/ST-43, ST-12), (CC-23/ST-163, ST-23), (CC-17/ST-17) and (CC-4/ST-16).ConclusionThe study shows an alarmingly high prevalence of erythromycin-resistant GBS in Iran. In addition, we report dissemination of ST-335/CPS-III clone associated with tetracycline and erythromycin resistance in our region. The distribution of capsular and pilus genotypes varies between invasive and colonizing GBS that could be helpful for vaccine development.

Monitoring Islands and Reefs Area Based on Satellite Remote Sensing Image

The distribution of islands and reefs is wide, and the field survey cost is high and difficult. After the identification of islands and reefs, how to carry out effective monitoring is also a problem. By comparing three remote sensing monitoring methods, this paper analyzes the advantages of satellite remote sensing image to obtain islands and reefs area monitoring methods, and puts forward three methods based on satellite remote sensing to monitor islands and reefs area, so as to provide reference for islands and reefs area monitoring.

Exploring diversification drivers in golden orbweavers

Heterogeneity in species diversity is driven by the dynamics of speciation and extinction, potentially influenced by organismal and environmental factors. Here, we explore macroevolutionary trends on a phylogeny of golden orbweavers (spider family Nephilidae). Our initial inference detects heterogeneity in speciation and extinction, with accelerated extinction rates in the extremely sexually size dimorphic Nephila and accelerated speciation in Herennia, a lineage defined by highly derived, arboricolous webs, and pronounced island endemism. We evaluate potential drivers of this heterogeneity that relate to organisms and their environment. Primarily, we test two continuous organismal factors for correlation with diversification in nephilids: phenotypic extremeness (female and male body length, and sexual size dimorphism as their ratio) and dispersal propensity (through range sizes as a proxy). We predict a bell-shaped relationship between factor values and speciation, with intermediate phenotypes exhibiting highest diversification rates. Analyses using SSE-class models fail to support our two predictions, suggesting that phenotypic extremeness and dispersal propensity cannot explain patterns of nephilid diversification. Furthermore, two environmental factors (tropical versus subtropical and island versus continental species distribution) indicate only marginal support for higher speciation in the tropics. Although our results may be affected by methodological limitations imposed by a relatively small phylogeny, it seems that the tested organismal and environmental factors play little to no role in nephilid diversification. In the phylogeny of golden orbweavers, the recent hypothesis of universal diversification dynamics may be the simplest explanation of macroevolutionary patterns.

Analysis of precise climate pattern of Maldives. A complex island structure

Republic of Maldives is located on the south and south-western region of the coast of India. The country is one of the most geographically dispersed nations in the world, with 1192 coral islands grouped into 26 natural atolls in the middle of the Indian Ocean. A descriptive study of its climatic conditions is presented in this work. We have used geostatistical technique of kriging (described below) for the estimation of meteorological variables. Complexity related to the structure of the region, with diverse distribution of islands of varying sizes, is discussed in connection to the analysis. Climatic characteristics explored in the current work indicate the need for subsequent studies of seasonal patterns in climate change, especially temperatures and precipitation across the country, and also to identify the effect of extreme climatic conditions and natural disasters such as Tsunamis. The results do not show periodicity over the study period. It emphasizes that climatic patterns appearing in the study area must be analyzed more extensively over time, with the inclusion of a greater number of meteorological stations for precise spatio-temporal analysis.

Investigating the land surface temperature reaction to the land cover patterns during three decades using landsat data

Land use Land cover changes have a momentous influence on land surface temperature. Therefore, investigating spatial distribution of heat islands is a remarkable issue in environmental studies. The purpose of this study was to assess the interaction between land surface temperature variations with land cover change by using Landsat time-series and utilizing Normalized Vegetation Difference Index in Arsanjan County, Fars, Iran from 1987 to 2018. After estimating Normalized Vegetation Difference Index and land surface temperature time-series value in the experimental areas, index differencing technique was applied to identify their changes. Based on the findings, the reducing or rising trends of land surface temperature in vegetation stratums was related to the increasing or decreasing trend of Normalized Vegetation Difference Index from 1987 to 2003 and 2003 to 2018, respectively. Compared to the period 1987–2003, it is noteworthy that the noticeable increase in changed land surface temperature in the rangeland, farmland and Bakhtegan Lake by 18.2 °C, 21.2 °C and 18.3 °C, respectively, were attributed to the significant shift of Normalized Vegetation Difference Index by − 0.04, − 0.33 and + 0.6 in the mentioned area during the period 2003–2018. The correlations between land cover and land surface temperature were considerably positive in the water area by 0.95 and 0.83 from 1987 to 2003 and 2003 to 2018, respectively, while some negative coefficients were estimated by − 0.95 and − 0.94 in farmland in the mentioned period. These results are applicable with regard to managing heat islands by improving the cultivated area, afforestation and artificial Bakhtegan Lake recharge.

Rhode Island's Opioid Overdose Hospital Standards and Emergency Department Naloxone Distribution, Behavioral Counseling, and Referral to Treatment

We sought to determine the influence of the Levels of Care for Rhode Island Emergency Departments and Hospitals for Treating Overdose and Opioid Use Disorder (Levels of Care) on emergency department (ED) provision of take-home naloxone, behavioral counseling, and referral to treatment. A retrospective analysis of Rhode Island ED visits for opioid overdose from 2017 to 2018 was performed using data from a statewide opioid overdose surveillance system. Changes in provision of take-home naloxone, behavioral counseling, and referral to treatment before and after Levels of Care implementation were assessed using interrupted time series analysis. We compared outcomes by hospital type using multivariable modified Poisson regression models with generalized estimating equation estimation to account for hospital-level variation. We analyzed 245 overdose visits prior to Levels of Care implementation (January to March 2017) and 1340 overdose visits after implementation (hospital certification to December 2018). After implementation, the proportion of patients offered naloxone increased on average by 13% (95% confidence interval [CI] 5.6% to 20.4%). Prior to implementation, the proportion of patients receiving behavioral counseling and treatment referral was declining. After implementation, this decline slowed and stabilized, and on average 18.6% more patients received behavioral counseling (95% CI 1.3% to 35.9%) and 23.1% more patients received referral to treatment (95% CI 2.7% to 43.5%). Multivariable analysis showed that after implementation, there was a significant increase in the likelihood of being offered naloxone at Level 1 (adjusted relative risk [aRR] 1.31 [95% CI 1.06 to 1.61]) and Level 3 (aRR 3.13 [95% CI 1.08 to 9.06]) hospitals and an increase in referrals for medication for opioid use disorder (from 2.5% to 17.8%) at Level 1 hospitals (RR 7.73 [95% CI 3.22 to 18.55]). Despite these increases, less than half of the patients treated for an opioid overdose received behavioral counseling or referral to treatment CONCLUSION: The establishment of ED policies for treatment and services after opioid overdose improved naloxone distribution, behavioral counseling, and referral to treatment at hospitals without previously established opioid overdose services. Future investigations are needed to better characterize implementation barriers and evaluate policy influence on patient outcomes.

Predicting Plastic Flow Behaviour, Failure Mechanisms and Severe Deformation Localisation of Dual-Phase Steel using RVE Simulation

In this work, the von Mises stress and plastic strain distribution of Ferrite-Martensite–Dual-Phase (FMDP) steels are predicted at various stages of deformation. The failure modes and volume fraction effect are identified based on Representative Volume Element (RVE). FMDP steel consists of a typical ferrite-matrix phase, in which martensite-islands are dispersed. Recently FMDP steels are increasingly used to the various car parts in demand. 2D-RVEs are also utilised to predict the orientations effect of the martensite phase in the FMDP steels. Based on the position of the element, the boundary conditions (BC) are given in the RVE of FMDP steel microstructures. The failure modes are examined in the form of severe plastic strain localisation. While the distribution of islands in the microstructure varies, as a result, the deformation inhomogeneity increases with a rise of martensite fraction. The results of numerical computation and the trend of experimental failure shown in the literature are compared. This is signifying that the overall macro-behaviour of FMDP steel, as a consequence of stress-strain partitioning and influence of martensite-island volume fractions (MVFs), can be predicted by the finite element (FE) based 2D-RVE modelling.

Lateral Distribution of Optical Excitation at Boundaries around Rubrene Islands Visualized by Microspot Two-Photon Photoemission Spectroscopy

The lateral distribution of optical excitation occurring at the edge part of rubrene (5,6,11,12-tetraphenyltetracene) molecular islands formed on highly oriented pyrolytic graphite (HOPG) substrate has been visualized with microspot two-photon photoemission (2PPE) spectroscopy of 0.4 µm resolution. As we reported previously [T. Ueba, et al., J. Phys. Chem. C 117 (2013) 20098–20103], an unoccupied peak labeled Ln is strongly enhanced in 2PPE spectroscopy by a resonant optical excitation between a diffuse unoccupied Ln molecular orbital and the HOMO. The strong enhancement is due to the hybridization of Ln with the image potential state (IPS) on the HOPG substrate. In this study, using the spatially-resolved microspot 2PPE method, we obtained the real space image of the area where the optical excitation occurs. One-photon photoelectron emission microscope (1PPE-PEEM) with 50 nm resolution is used to compare with the microspot 2PPE. The 1PPE-PEEM images are homogeneous for films below and above 1 monolayer (ML) coverage, indicating that the molecular density of rubrene is homogeneous within the lateral resolution. On the other hand, microspot 2PPE images for sub-ML films show inhomogeneous areas of several µm sizes. The images depend on the detected unoccupied levels of interest. The inhomogeneity is very significant when the image is recorded at the energy of Ln peak. The different appearance between 1PPE-PEEM and microspot 2PPE images is explained on the basis that the Ln excitation occurs at the edges of islands smaller than the resolution of the PEEM. Though the microspot 2PPE achieves only moderate lateral resolution, it is sensitive to the resonant excitation occurring at nm-scale boundaries of the molecular islands. The distribution of the nm-scale islands is the origin of the µm-scale lateral inhomogeneity. The microspot 2PPE images become homogeneous for films thicker than 1 ML, reflecting the quenching of the resonant excitation. These results demonstrate a possibility that spatially- and energy-resolved microspot 2PPE can be a powerful tool to clarify nanoscale geometric and electronic structures at the molecule/substrate interfaces.