Homogeneous Map Research Articles

The BINGO Project

Context.The Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) telescope was designed to measure the fluctuations of the 21 cm radiation arising from the hyperfine transition of neutral hydrogen. It is also aimed at measuring the baryon acoustic oscillations (BAO) from such fluctuations, thereby serving as a pathfinder to future, deeper intensity mapping surveys. The requirements for the Phase 1 of the projects consider a large reflector system (two 40 m-class dishes in a crossed-Dragone configuration) illuminating a focal plane with 28 horns to measure the sky, with two circular polarizations in a drift scan mode to produce measurements of the radiation in intensity (I) as well as the circular (V) polarization.Aims.In this paper, we present the optical design for the instrument. We describe the optical arrangement of the horns in the focal plane to produce a homogeneous and well-sampled map after the end of Phase 1, as well as the intensity and polarization properties of the beams. Our analysis provides an optimal model for the location of the horns in the focal plane, producing a homogeneous and Nyquist-sampled map after the nominal survey time.Methods.We used the GRASP package to model the focal plane arrangement and performed several optimization tasks to arrive at the current configuration, including an estimation of the sidelobes corresponding to the diffraction patterns of the two mirrors. The final model for the focal plane was defined through a combination of neural network and other direct optimization methods.Results.We arrived at an optimal configuration for the optical system that includes the focal plane positioning and the beam behavior of the instrument. We present an estimate of the expected sidelobes both for intensity and polarization, as well as the effect of band averaging on the final sidelobes, as well as an estimation of the cross-polarization leakage for the final configuration.Conclusions.We conclude that the chosen optical design meets the requirements for the project in terms of polarization purity and area coverage as well as a homogeneity of coverage so that BINGO can perform a successful BAO experiment. We further conclude that the requirements on the placement and rms error on the mirrors are also achievable so that a successful experiment can be conducted.

Threshold dynamics of a nonlocal and time-delayed West Nile virus model with seasonality

In this paper, we study a nonlocal periodic reaction–diffusion system modeling the West Nile virus transmission between mosquitoes and birds. For the subsystem of mosquito growth, we establish a global stability result on the extinction and persistence in terms of mosquito reproduction number RM, which is defined as the cone spectral radius of a monotone homogeneous map. For the full model, we introduce the basic reproduction number R0 and show that the disease transmission dynamics is determined by the sign of R0−1 under the assumption that RM>1. Moreover, we obtain the global attractivity of the positive constant steady state in the case where all the coefficients are constants. We also conduct numerical simulations to reveal the effects of diffusion, heterogeneity and periodic delay on R0.

The Łojasiewicz exponent of weighted homogeneous polynomials at infinity

Let f: Cn⟶C be a weighted homogeneous polynomial with a finite number of critical points. The aim of this paper is to give a formula for the Łojasiewicz exponent of f at infinity in terms of its weights wi, when wi≥2. We also give a characterization of properness for weighted homogeneous polynomial mapppings. As a corollary, we prove the Jacobian conjecture for weighted and preweighted homogeneous polynomial mappings with positive weights.

Altered Spontaneous Brain Activity in Patients With Diabetic Osteoporosis Using Regional Homogeneity: A Resting-State Functional Magnetic Resonance Imaging Study.

BackgroundThe pathophysiological mechanism of cognitive impairment by osteoporosis in type 2 diabetes mellitus (T2DM) remains unclear. This study aims to further investigate the regional spontaneous brain activity changes of patients with diabetic osteoporosis (DOP), and the correlation between abnormal brain regions and bone metabolites.MethodsA total of 29 subjects with T2DM were recruited, including fourteen patients with DOP and thirteen patients without osteoporosis (Control group). Based on the resting-state functional magnetic resonance imaging (rs-fMRI) datasets acquired from all the subjects, a two-sample t-test was performed on individual normalized regional homogeneity (ReHo) maps. Spearman correlation analysis was performed between the abnormal ReHo regions with the clinical parameters and Montreal Cognitive Assessment (MOCA) scores.ResultsIn the DOP group, we demonstrated the significantly increased ReHo values in the left middle temporal gyrus (MTG), right superior occipital gyrus (SOG), aright superior parietal lobule (SPL), right angular gyrus (AG), and left precuneus (PE). Additionally, we also found a significant positive correlation between increased ReHo values in the left MTG and the average bone mineral density (BMD AVG), and average T scores (T AVG). The ReHo values of the right SOG and right SPL showed a negative correlation with MOCA scores, as well as a negative correlation between increased ReHo values in the right SPL and osteocalcin (OC) level.ConclusionPatients with DOP showed increased spontaneous activity in multiple brain regions. The results indicated that osteoporosis exacerbated cognitive impairment and brain damage. Also, the OC might be considered as a bone marker to track the progression of cognitive impairment.

Image-Scale-Symmetric Cooperative Network for Defocus Blur Detection

Defocus blur detection (DBD) for natural images is a challenging vision task especially in the presence of homogeneous regions and gradual boundaries. In this paper, we propose a novel image-scale-symmetric cooperative network (IS2CNet) for DBD. On one hand, in the process of image scales from large to small, IS2CNet gradually spreads the recept of image content. Thus, the homogeneous region detection map can be optimized gradually. On the other hand, in the process of image scales from small to large, IS2CNet gradually feels the high-resolution image content, thereby gradually refining transition region detection. In addition, we propose a hierarchical feature integration and bi-directional delivering mechanism to transfer the hierarchical feature of previous image scale network to the input and tail of the current image scale network for guiding the current image scale network to better learn the residual. The proposed approach achieves state-of-the-art performance on existing datasets. <i>Codes and results are available at: <uri>https://github.com/wdzhao123/IS2CNet</uri></i>.

EVALUASI KESESUAIAN LAHAN KERING UNTUK TANAMAN PANGAN DI KECAMATAN KUBUTAMBAHAN KABUPATEN BULELENG

Dry land is land whose use for the development of agricultural commodities is limited, due to constraints on the availability of nutrients and water. The research objectives are: to identify the suitability of dry land for upland rice, corn and peanuts; identify limiting factors and improvement efforts to increase land productivity. The method used is a survey to determine the characteristics of the land in the field and to take soil samples that are analyzed in the laboratory. Determination of sample points based on the results of overlapping maps of soil types, land use maps, slope maps using QGIS 3.4, so that a homogeneous land unit map (SLH) is obtained, and 6 SLH is obtained as observation points. The results of field and laboratory data analysis were matched with the growing requirements for upland rice, corn and peanuts. The actual land suitability for upland rice, corn, and peanuts is classified as S2 (fairly suitable) to N (not suitable). The limiting factors are slope, erosion hazard, temperature, texture, rainfall, pH, N-total, P2O5, Cation Exchange Capacity, Base Saturation, availability of oxygen, and C-organic. Improvement efforts that must be done are making terraces, fertilizing urea, fertilizers containing phosphate, mulching using plant residues, giving organic matter, and improving drainage. After improving the limiting factors that can be improved, the potential land suitability classes for upland rice, corn and peanuts are S1 (very suitable), S2 (fairly suitable) and S3 (marginally appropriate).

Forest Degradation Impact on Soil Organic Carbon - A Geospatial Approach

Soil organic carbon (SOC) is one of the soil health indicators. Forest soils are negatively impacted by biotic interference and the authors impact from forest canopy cover amenable to Earth Observation data. We mapped forest cover types and canopy density using remote sensing data. Sample design and size were based on the stratification and homogeneity map. The soil samples were collected from three depths using the pit method for analysis and SOC stock estimation. A linear and positive correlation between SOC and forest cover density was observed, indicating the negative impact of forest degradation on SOC. The maximum SOC stock of 61.16 ± SE3.96 Mg ha -1 was observed in top 30 cm soil in Sal forests with &gt;80% canopy density and minimum (25.64 Mg ha -1 ) in Sal-mixed Teak forests with 40-60% canopy density. Total SOC ranged from 68.98 ± SE11.38 Mg ha -1 in the Hill Sal forest with 10-40% canopy density to 179.05 ± SE11.20 Mg ha -1 in pure Sal forests with &gt;80% canopy density. It revealed that forest canopy degradation due to biotic interference caused loss of SOC in almost all the soil layers. SOC geospatial map shows areas for protection and reforestation/enrichment planting to enhance soil carbon stock.

Tail measures and regular variation

A general framework for the study of regular variation (RV) is that of Polish star-shaped metric spaces, while recent developments in [1] have discussed RV with respect to some properly localised boundedness $\mathcal{B}$ imposing weak assumptions on the structure of Polish space. Along the lines of the latter approach, we discuss the RV of Borel measures and random processes on general Polish metric spaces. Tail measures introduced in [2] appear naturally as limiting measures of regularly varying time series. We define tail measures on a measurable space indexed by $\mathcal{H}(D)$, a countable family of homogeneous coordinate maps, and show some tractable instances for the investigation of RV when $\mathcal{B}$ is determined by $\mathcal{H}(D)$. This allows us to study the regular variation of cadlag processes on $D(R^l, R^d)$ retrieving in particular results obtained in [1] for RV of stationary cadlag processes on the real line removing $l=1$ therein. Further, we discuss potential applications and open questions.

Impact on ALFF and ReHO mapping of lifestyle multidomain intervention: The SUPERBRAIN study

AbstractBackgroundIn the South Korean study to prevent cognitive impairment and protect brain health through lifestyle intervention in at‐risk elderly people (SUPERBRAIN), we explored impact on amplitude of low‐frequency fluctuation (ALFF) and regional homogeneity (ReHo) mapping of 24‐week facility‐based multidomain intervention (FMI) and home‐based MI (HMI).MethodA total of 152 participants, aged 60‐79 years without dementia but with ≥ 1 modifiable dementia risk factor, were randomly assigned to the FMI, HMI, or control groups. Among them, 56 participants (20 FMI, 20 HMI, and 16 control) took brain MRIs at baseline and 24 weeks. We compared between each intervention and control groups in change of ALFF and ReHo mapping. The changes in ALFF and ReHo mapping were compared using analysis of covariance with age, sex, education, and scan centers as covariates. ROI‐based analysis was controlled for multiple comparisons with a false discovery rate threshold of P &lt; 0.05.ResultOnly in the FMI group, a significant increase of ALFF in left medial orbitofrontal gyrus was observed after intervention. When 24‐week ALFF change in the left medial orbitofrontal gyrus was compared between each intervention and control groups, there was no difference. In HMI, increased ReHo was evident in right cuneus at follow‐up, whereas increased ReHo in left medial orbitofrontal gyrus and left anterior cingulate and decreased ReHo in right superior parietal lobule and right precuneus were observed in FMI group. The ReHo change in right cuneus was significantly higher in HMI group compared to the control group. The ReHo change in left medial orbitofrontal gyrus was notably higher in FMI compared to the control group. The correlation analysis revealed a positive correlation between the ReHo change in left medial orbitofrontal gyrus and change of serum brain‐derived neurotrophic factor (BDNF) levels in FMI group.ConclusionSignificant differences between the FMI and control groups on changes in ReHo in at‐risk elderly without substantial impairment in the SUPERBRAIN suggest that group preventive strategies at the facility may be beneficial on cognition through neuroplastic changes of functional processing circuits in the brain areas which play a crucial role in processing social information.

A Multimodal Fusion Analysis of Pretreatment Anatomical and Functional Cortical Abnormalities in Responsive and Non-responsive Schizophrenia.

Background: Antipsychotic medications provide limited long-term benefit to ~30% of schizophrenia patients. Multimodal magnetic resonance imaging (MRI) data have been used to investigate brain features between responders and nonresponders to antipsychotic treatment; however, these analytical techniques are unable to weigh the interrelationships between modalities. Here, we used multiset canonical correlation and joint independent component analysis (mCCA + jICA) to fuse MRI data to examine the shared and specific multimodal features between the patients and healthy controls (HCs) and between the responders and non-responders.Method: Resting-state functional and structural MRI data were collected from 55 patients with drug-naïve first-episode schizophrenia (FES) and demographically matched HCs. Based on the decrease in Positive and Negative Syndrome Scale scores from baseline to the 1-year follow-up, FES patients were divided into a responder group (RG) and a non-responder group (NRG). Gray matter volume (GMV), fractional amplitude of low-frequency fluctuation (fALFF), and regional homogeneity (ReHo) maps were used as features in mCCA + jICA.Results: Between FES patients and HCs, there were three modality-specific discriminative independent components (ICs) showing the difference in mixing coefficients (GMV-IC7, GMV-IC8, and fALFF-IC5). The fusion analysis indicated one modality-shared IC (GMV-IC2 and ReHo-IC2) and three modality-specific ICs (GMV-IC1, GMV-IC3, and GMV-IC6) between the RG and NRG. The right postcentral gyrus showed a significant difference in GMV features between FES patients and HCs and modality-shared features (GMV and ReHo) between responders and nonresponders. The modality-shared component findings were highlighted by GMV, mainly in the bilateral temporal gyrus and the right cerebellum associated with ReHo in the right postcentral gyrus.Conclusions: This study suggests that joint anatomical and functional features of the cortices may reflect an early pathophysiological mechanism that is related to a 1-year treatment response.

Maternal pre-pregnancy BMI associates with neonate local and distal functional connectivity of the left superior frontal gyrus

Maternal obesity/overweight during pregnancy has reached epidemic proportions and has been linked with adverse outcomes for the offspring, including cognitive impairment and increased risk for neuropsychiatric disorders. Prior neuroimaging investigations have reported widespread aberrant functional connectivity and white matter tract abnormalities in neonates born to obese mothers. Here we explored whether maternal pre-pregnancy adiposity is associated with alterations in local neuronal synchrony and distal connectivity in the neonate brain. 21 healthy mother-neonate dyads from uncomplicated pregnancies were included in this study (age at scanning 26.14 ± 6.28 days, 12 male). The neonates were scanned with a 6-min resting-state functional magnetic resonance imaging (rs-fMRI) during natural sleep. Regional homogeneity (ReHo) maps were computed from obtained rs-fMRI data. Multiple regression analysis was performed to assess the association of pre-pregnancy maternal body-mass-index (BMI) and ReHo. Seed-based connectivity analysis with multiple regression was subsequently performed with seed-ROI derived from ReHo analysis. Maternal adiposity measured by pre-pregnancy BMI was positively associated with neonate ReHo values within the left superior frontal gyrus (SFG) (FWE-corrected p < 0.005). Additionally, we found both positive and negative associations (p < 0.05, FWE-corrected) for maternal pre-pregnancy BMI and seed-based connectivity between left SFG and prefrontal, amygdalae, basal ganglia and insular regions. Our results imply that maternal pre-pregnancy BMI associates with local and distal functional connectivity within the neonate left superior frontal gyrus. These findings add to the evidence that increased maternal pre-pregnancy BMI has a programming influence on the developing neonate brain functional networks.

Mapping Crop Types and Cropping Systems in Nigeria with Sentinel-2 Imagery

Reliable crop type maps from satellite data are an essential prerequisite for quantifying crop growth, health, and yields. However, such maps do not exist for most parts of Africa, where smallholder farming is the dominant system. Prevalent cloud cover, small farm sizes, and mixed cropping systems pose substantial challenges when creating crop type maps for sub-Saharan Africa. In this study, we provide a mapping scheme based on freely available Sentinel-2A/B (S2) time series and very high-resolution SkySat data to map the main crops—maize and potato—and intercropping systems including these two crops on the Jos Plateau, Nigeria. We analyzed the spectral-temporal behavior of mixed crop classes to improve our understanding of inter-class spectral mixing. Building on the Framework for Operational Radiometric Correction for Environmental monitoring (FORCE), we preprocessed S2 time series and derived spectral-temporal metrics from S2 spectral bands for the main temporal cropping windows. These STMs were used as input features in a hierarchical random forest classification. Our results provide the first wall-to-wall crop type map for this key agricultural region of Nigeria. Our cropland identification had an overall accuracy of 84%, while the crop type map achieved an average accuracy of 72% for the five relevant crop classes. Our crop type map shows distinctive regional variations in the distribution of crop types. Maize is the dominant crop, followed by mixed cropping systems, including maize–cereals and potato–maize cropping; potato was found to be the least prevalent class. Plot analyses based on a sample of 1166 fields revealed largely homogeneous mapping patterns, demonstrating the effectiveness of our classification system also for intercropped classes, which are temporally and spatially highly heterogeneous. Moreover, we found that small field sizes were dominant in all crop types, regardless of whether or not intercropping was used. Maize–legume and maize exhibited the largest plots, with an area of up to 3 ha and slightly more than 10 ha, respectively; potato was mainly cultivated on fields smaller than 0.5 ha and only a few plots were larger than 1 ha. Besides providing the first spatially explicit map of cropping practices in the core production area of the Jos Plateau, Nigeria, the study also offers guidance for the creation of crop type maps for smallholder-dominated systems with intercropping. Critical temporal windows for crop type differentiation will enable the creation of mapping approaches in support of future smart agricultural practices for aspects such as food security, early warning systems, policies, and extension services.

An asymmetrical whole-body birdcage RF coil without RF shield for hyperpolarized 129 Xe lung MR imaging at 1.5 T.

This study describes the development and testing of an asymmetrical xenon-129 (129 Xe) birdcage radiofrequency (RF) coil for 129 Xe lung ventilation imaging at 1.5 Tesla, which allows proton (1 H) system body coil transmit-receive functionality. The 129 Xe RF coil is a whole-body asymmetrical elliptical birdcage constructed without an outer RF shield to enable 1 H imaging. field homogeneity and flip angle mapping of the 129 Xe birdcage RF coil and 1 H system body RF coil with the 129 Xe RF coil in situ were evaluated in the MR scanner. The functionality of the 129 Xe birdcage RF coil was demonstrated through hyperpolarized 129 Xe lung ventilation imaging with the birdcage in both transceiver configuration and transmit-only configuration when combined with an 8-channel 129 Xe receive-only RF coil array. The functionality of 1 H system body coil with the 129 Xe RF coil in situ was demonstrated by acquiring coregistered 1 H lung anatomical MR images. The asymmetrical birdcage produced a homogeneous field (±10%) in agreement with electromagnetic simulations. Simulations indicated an optimal detuning configuration with 4 diodes. The obtained g-factor of 1.4 for acceleration factor of R = 2 indicates optimal array configuration. Coregistered 1 H anatomical images from the system body coil along with 129 Xe lung images demonstrated concurrent and compatible arrangement of the RF coils. A large asymmetrical birdcage for homogenous transmission with high sensitivity reception for 129 Xe lung MRI at 1.5 Tesla has been demonstrated. The unshielded asymmetrical birdcage design enables 1 H structural lung MR imaging in the same exam.

Improving parametric estimation in the brain from multispin-echo sequences using a fusion bootstrap moves solver.

To simultaneously estimate the field (along with the T2 ) in the brain with multispin-echo (MSE) sequences and dictionary matching. T2 mapping provides clinically relevant information such as in the assessment of brain degenerative diseases. It is commonly obtained with MSE sequences, and accuracy can be further improved by matching the MSE signal to a precomputed dictionary of echo-modulation curves. For additional T1 quantification, transmit field knowledge is also required. Preliminary work has shown that although simultaneous brain estimation along with T2 is possible, it presents a bimodal distribution with the main peak coinciding with the true value. By taking advantage of this, the maps are expected to be spatially smooth by applying an iterative method that takes into account each pixel neighborhood known as the fusion bootstrap moves solver (FBMS). The effect of the FBMS on accuracy and piecewise smoothness is investigated and different spatial regularization levels are compared. Total variation regularization was used for both and T2 simultaneous estimation because of its simplicity as an initial proof-of-concept; future work could explore non edge-preserving regularization independently for . Improvements in accuracy (up to 45.37% and 16.81% error decrease) and recovery of spatially homogeneous maps are shown in simulations and in vivo 3.0T brain data, respectively. Accurate estimated values can be obtained from widely available MSE sequences while jointly estimating T2 maps with the use of echo-modulation curve matching and FBMS at no further cost.

Unique solvability of weakly homogeneous generalized variational inequalities

An interesting observation is that most pairs of weakly homogeneous mappings do not possess strongly monotonic property, which is one of the key conditions to ensure the unique solvability of the generalized variational inequality. This paper focuses on studying the uniqueness and solvability of the generalized variational inequality with a pair of weakly homogeneous mappings. By using a weaker condition than the strong monotonicity and some additional conditions, we achieve several results on the unique solvability to the underlying problem, which are exported by making use of the exceptional family of elements. As an adjunct, we also obtain the nonemptiness and compactness of the solution sets to the weakly homogeneous generalized variational inequality under some appropriate conditions. The conclusions presented in this paper are new or supplements to the existing ones even when the problem comes down to its important subclasses studied in recent years.

Sharing Soil and Building Geophysical Data for Seismic Characterization of Cities Using CLARA WebGIS: A Case Study of Matera (Southern Italy)

In the context of seismic risk, studying the characteristics of urban soils and of the built environment means adopting a holistic vision of the city, taking a step forward compared to the current microzonation approach. Based on this principle, CLARA WebGIS aims to collect, organize, and disseminate the available information on soils and buildings in the urban area of Matera. The geodatabase is populated with (i) 488 downloadable geological, geotechnical, and geophysical surveys; (ii) geological, geomorphological, and seismic homogeneous microzone maps; and (iii) a new Digital Surface Model. The CLARA WebGIS is the first publicly available database that reports for the whole urban area the spatial distribution of the fundamental frequencies for soils and the overlying 4043 buildings, along with probability levels of soil-building resonance. The WebGIS is aimed at a broad range of end users (local government, engineers, geologists, etc.) as a support to the implementation of seismic risk mitigation strategies in terms of urban planning, seismic retrofitting, and management of post-earthquake crises. We recommend that the database be managed by local administrators, who would also have the task of deciding on future developments and continuous updating as new data becomes available.

GAKTpore: Stereological Characterisation Methods for Porous Foams in Biomedical Applications.

In tissue engineering, scaffolds are a key component that possess a highly elaborate pore structure. Careful characterisation of such porous structures enables the prediction of a variety of large-scale biological responses. In this work, a rapid, efficient, and accurate methodology for 2D bulk porous structure analysis is proposed. The algorithm, “GAKTpore”, creates a morphology map allowing quantification and visualisation of spatial feature variation. The software achieves 99.6% and 99.1% mean accuracy for pore diameter and shape factor identification, respectively. There are two main algorithm novelties within this work: (1) feature-dependant homogeneity map; (2) a new waviness function providing insights into the convexity/concavity of pores, important for understanding the influence on cell adhesion and proliferation. The algorithm is applied to foam structures, providing a full characterisation of a 10 mm diameter SEM micrograph (14,784 × 14,915 px) with 190,249 pores in ~9 min and has elucidated new insights into collagen scaffold formation by relating microstructural formation to the bulk formation environment. This novel porosity characterisation algorithm demonstrates its versatility, where accuracy, repeatability, and time are paramount. Thus, GAKTpore offers enormous potential to optimise and enhance scaffolds within tissue engineering.

Seamless maps of major elements of the Moon: Results from high-resolution geostationary satellite

Major elements such as Fe, Ti, Mg, Al, Ca and Si play very important roles in understanding the origin and evolution of the Moon. Previous maps of these major elements derived from orbital data are based on mosaic images or low-resolution gamma-ray data. The hue variations and gaps among orbital boundaries in the mosaic images are not conducive to geological studies. This paper aims to produce seamless and homogenous distribution maps of major elements using the single-exposure image of the whole lunar disk obtained by China’s high-resolution geostationary satellite, Gaofen-4, with a spatial resolution of ∼ 500 m. The elemental contents of soil samples returned by Apollo and Luna missions are regarded as ground truth, and are correlated with the reflectance of the sampling sites extracted from Gaofen-4 data. The final distribution maps of these major oxides are generated with the statistical regression model. With these products, the average contents and proportions of the major elements for maria and highlands were estimated and compared. The results showed that SiO2 and TiO2 have the highest and lowest fractions in mare and highland areas, respectively. Moreover, the relative concentrations of these elements could serve as indicators of geologic processes, e.g., the obviously asymmetric distributions of Al2O3, CaO and SiO2 around Tycho crater may suggest that Tycho crater was formed by an oblique impact from the southwest direction.

A rapid qualitative methodology for ecological integrity assessment across a Mediterranean island's landscapes

Rapid qualitative field methods can be used to evaluate ecological integrity (EI) at a landscape level. This study evaluates the EI of 63 landscape types (LCTs) in Cyprus derived from Landscape Character Mapping. Following a stratified sampling, LCTs were evaluated using 209 Land Description Units (LDUs) i.e., homogeneous map entities, sharing a similar pattern of natural and cultural elements. In every LDU, six ecological integrity (EI) indicators were visually assessed consistently namely naturalness, habitat continuity, number of habitats, dominant habitat type, management intensity and scale. TwoStep Cluster Analysis was employed to identify EI categories, and Categorical Principal Components Analysis (CATPCA) to associate the individual indicators with overall EI in the LDUs. Linear regressions were used to predict EI based on the most important indicators. Forested and shrubland landscapes have consistently good EI with low variation, while urbanized and agricultural landscapes have lower EI. There is great variation in the number of agricultural landscape types and their EI. There are significant linear relationships between EI and naturalness, habitat continuity and intensity. The novelty of this work lies with the fact that it provides the first island-wide study in the Mediterranean assessing EI spatially through a small number of indicators. Results indicate that LCA can be an appropriate consistent and inexpensive spatial framework for assessing EI, which can be directly associated with management intervention to maintain or improve EI.

Quadratic maps in two variables on arbitrary fields

Let F be a field of characteristic different from 2 and 3, and let V be a vector space of dimension 2 over F. The generic classification of homogeneous quadratic maps f : V → V under the action of the linear group of V , is given and efficient computational criteria to recognize equivalence are provided.