Quadrat Size Research Articles

Constructing red-black spanners for mixed-charging vehicular networks

Motivated by the recent trend of increasing number of e-cars and hybrid cars, we investigate the problem of building a red-black spanner for a mixed-charging vehicular network. In such a network, we have two kinds of gas/charging stations: electric (black) and the traditional gas (red) stations. Our requirement is that one cannot connect two gas stations directly in the spanner (i.e., no red-red edge), and the goal is to build a linear-size spanner with a bounded stretch factor under this requirement. (In 2-d, it can be shown that a spanner with an optimal stretch factor could have a quadratic size and if one is constrained to build the spanner purely from a given road network then it is impossible to obtain a bounded stretch factor.) Our main results are summarized as follows.1.In 1-d, a linear-size red-black spanner is built to satisfy the ‘no red-red edge’ requirement which achieves the optimal stretch factor.2.In 2-d and under the L2 metric, we build a linear-size red-black spanner satisfying the ‘no red-red edge’ requirement which achieves a stretch factor of 1.998.3.In 2-d and under the L1 metric, a linear-size red-black spanner is built to satisfy the ‘no red-red edge’ requirement which achieves a stretch factor of 3.613.

Baseline Survey of Plant Species Along Salang Road in Afghanistan

The Salang Road, a critical transportation corridor, serves as a vital link connecting the northern and southern parts of Afghanistan. In response to the government's decision to upgrade this road, assessing and documenting the plant species in the region is crucial. This study was conducted to catalog the plant species along the Salang Road, aiming to establish a comprehensive understanding of the area's botanical diversity. Plants were recorded using the quadrate sampling method at 35 sampling points. A transect line was set up at each sampling point, 5 quadrats were established along each line, and the occurrence of plants within the quadrat frame was recorded. Quadrat sizes, determined using the minimal area method, were 10×10 m for trees, 2×5 m for shrubs, and 1 m2 for herbs. Plants were identified with the help of literature and by comparing with the deposited specimen of Kabul University Faculty of Sciences Herbarium (KUFS). Data were analyzed using Microsoft Excel. 135 diverse species, including trees, shrubs, and herbs, representing various ecological niches were documented. These species belong to 46 plant families, and the most abundant ones were Asteraceae, Apiaceae, Rosaceae, Lamiaceae, Fabaceae, and Polygonaceae. The survey additionally examined road construction's impact on plant species' distribution and diversity. The survey provides valuable insights into the Salang corridor area's botanical diversity and ecological significance, serving as a foundational dataset for future environmental conservation and land management efforts. The information obtained from this study can support qualified decision-making and sustainable development practices in the region.

Long-term grazing changed the spatial distributions of dominant species in typical steppe of Inner Mongolia

Dominant species occupy a pivotal role in plant community, influencing the structure and function of the ecosystem. The spatial distributions of dominant species can react to the effect of different grazing intensities, thereby reflecting their tolerance and adaptive strategies toward grazing. In this study, geostatistical methods were mainly used to study the spatial distribution characteristics of Stipa krylovii Roshev. and Leymus chinensis (Trin.) Tzvel. species at two interval scales (quadrat size 5 m × 5 m, 10 m × 10 m) and two treatments (free grazing, FG, 1.66 sheep·ha− 1·a− 1; control, CK, 0 sheep·ha− 1·a− 1) in typical steppe of Inner Mongolia. A systematic sampling method was used in each 100 m × 100 m representative sample plots to obtain the height, coverage, and density of all species in the community. The results showed that grazing altered the concentrated distribution of S. krylovii and the spatial mosaic distribution pattern of S. krylovii and L. chinensis while having no effect on the spatial clumped distribution of L. chinensis. It also found that the spatial distributions of dominant species are primarily affected by structural factors, and random factors such as long-term grazing led to a transition of S. krylovii from a concentrated distribution to a small patchy random pattern should not be overlooked. Our findings suggest that long-term grazing alters the spatial distribution pattern of dominant species and that adaptive strategies may be the key for maintaining the dominant role of structural factors.

Heavy metals accumulation in lichens Parmeliaceae and mahogany bark as an indicator of air and pollution levels in several locations in Bandung City

Background: Lichens and tree bark are well-known biomonitoring tools for accumulating pollutants in their tissues over an extended period. Objective: This study aims to determine the concentration of heavy metals accumulated in lichens and tree bark across various locations in Bandung City, analyze the impact of heavy metal accumulation on lichen diversity, and assess the lichen cover area on tree bark. Methods: Lichen and bark samples were collected from mahogany trees using plotless sampling at a height of 100 cm, employing a quadrat size of 20x32 cm² above the ground. A total of 25 sampling stations were distributed across five locations in Bandung City, including city parks, an urban forest park, and a bus station. The samples were analyzed using Atomic Absorption Spectrophotometry (AAS) to measure the concentration of heavy metals. Results: The results revealed that lichens and bark from Persib City Park (PCP) contained the highest concentration of chromium (Cr), with 17.08 μg/kg in lichens and 30.03 μg/kg in the bark, as well as lead (Pb), with 24.38 μg/kg in lichens and 15.49 μg/kg in the bark. Conversely, lichens and bark from Djuanda Forest Park (DFP) exhibited the lowest concentration of chromium (3.74 μg/kg in lichens and 3.56 μg/kg in the bark) and lead (3.74 μg/kg in lichens and 2.06 μg/kg in the bark). PCA analysis indicated that the accumulation of heavy metals in lichens and bark was associated with environmental factors, such as traffic density and bark pH. Conclusion: The accumulation of heavy metals in lichens and bark exhibited a negative correlation with lichen diversity and the area of lichen cover on the bark.

A computational approach to identify the material parameters of the relaxed micromorphic model

We determine the material parameters in the relaxed micromorphic generalized continuum model for a given periodic microstructure in this work. This is achieved through a least squares fitting of the total energy of the relaxed micromorphic homogeneous continuum to the total energy of the fully-resolved heterogeneous microstructure, governed by classical linear elasticity. We avoid establishing exact micro–macro transition relations, as in classical homogenization theory, because defining a representative volume element is not feasible in the absence of scale separation, as such an element does not exist. The relaxed micromorphic model is a generalized continuum that utilizes the Curl of a micro-distortion field instead of its full gradient as in the classical micromorphic theory, leading to several advantages and differences. The most crucial advantage is that it operates between two well-defined scales. These scales are determined by linear elasticity with microscopic and macroscopic elasticity tensors, which respectively bound the stiffness of the relaxed micromorphic continuum from above and below. While the macroscopic elasticity tensor is established a priori through standard periodic first-order homogenization, the microscopic elasticity tensor remains to be determined. Additionally, the characteristic length parameter, associated with curvature measurement, controls the transition between the micro- and macro-scales. Both the microscopic elasticity tensor and the characteristic length parameter are here determined using a computational approach based on the least squares fitting of energies. This process involves the consideration of an adequate number of quadratic deformation modes and different specimen sizes. We conduct a comparative analysis between the least square fitting results of the relaxed micromorphic model, the fitting of a skew-symmetric micro-distortion field (Cosserat-micropolar model), and the fitting of the classical micromorphic model with two different formulations for the curvature; one simplified formulation involving only one single characteristic length and a simplified isotropic curvature with three parameters. The relaxed micromorphic model demonstrates good agreement with the fully-resolved heterogeneous solution after optimizing only four parameters. The “simplified” full micromorphic model, which includes isotropic curvature and involves the optimization of seven parameters, does not achieve superior results, while the Cosserat model exhibits the poorest fitting.

The Cerebellar Response to Visual Portion Size Cues Is Associated with the Portion Size Effect in Children.

The neural mechanisms underlying susceptibility to eating more in response to large portions (i.e., the portion size effect) remain unclear. Thus, the present study examined how neural responses to portion size relate to changes in weight and energy consumed as portions increase. Associations were examined across brain regions traditionally implicated in appetite control (i.e., an appetitive network) as well as the cerebellum, which has recently been implicated in appetite-related processes. Children without obesity (i.e., BMI-for-age-and-sex percentile < 90; N = 63; 55% female) viewed images of larger and smaller portions of food during fMRI and, in separate sessions, ate four meals that varied in portion size. Individual-level linear and quadratic associations between intake (kcal, grams) and portion size (i.e., portion size slopes) were estimated. The response to portion size in cerebellar lobules IV-VI was associated with the quadratic portion size slope estimated from gram intake; a greater response to images depicting smaller compared to larger portions was associated with steeper increases in intake with increasing portion sizes. Within the appetitive network, neural responses were not associated with portion size slopes. A decreased cerebellar response to larger amounts of food may increase children's susceptibility to overeating when excessively large portions are served.

Distribution and Regeneration Status of Albizia gummifera and Prunus africana along Agroecology in Agroforestry: The Case of Gombora District, Southern Ethiopia

Empirical evidence on the patterns of the multipurpose trees distribution and regeneration status, which are under threats pressure is necessary for the proper management and conservation of the species. Prunus africana is listed as vulnerable while Albizia gummifera is listed as least concern amongst the multipurpose trees. This study was aimed to investigate the distribution, abundance, density, and regeneration status of Prunus africana and Albizia gummifera along agroecology and farmers’ wealth status in agroforestry. Stratification sampling and equal sampling techniques were employed. A total of 162 quadrats were laid within the randomly selected 54 households’ farms. A nested quadrat size was 20 m × 20 m for enset tree-based homegarden and parklands. For live fencing, a quadrat size was 4 m × 10 m. Abundance, diameter (cm), height (m), and growth habits of both trees were recorded. Density (stems per ha), diameter class (cm), height (m) class of both trees, and mean of growth habit were analyzed and considered. One-way ANOVA analysis and independent t-test were employed for means comparison by using SPSS V. 23.0. A total of 132 individual A. gummifera was recorded along agroecology while a total of 55 individual P. africana was recorded along agroecology. Mean density (stem/ha) of A. gummifera and P. africana showed significant difference between agroecology and farmers’ wealth groups (P&lt;0.05). A. gummifera and P. africana were sparsely distributed in the enset tree-based homegarden, parklands, and live fencing along agroecology. The overall diameter (cm) class and height (m) class distribution pattern of these tree species were observed as a J-shaped curve. The regeneration status of A. gummifera and P. africana was poor. In conclusion, distribution, abundance, and regeneration status of A. gummifera and P. africana were influenced by agroecology and farmers’ wealth status needing appropriate conservation measures.

Influence of soil physicochemical properties on diversity and distribution of aquatic vegetation in the riverine forested habitats

Riverine flora is one of the most dynamic aspects of a landscape, and it involves species which are adapted and specialised to grow in a range of environmental conditions. An ecological analysis was conducted to describe the phyto-sociological and floristic structure of the plant species in the riverine forest at Balloki along moisture gradients caused by river bank. A random quadrat method with a quadrat size of 1 × 1 m was used for sampling of the riverine site. All plant species growing in the riverine habitats were collected and identified. A detailed survey was conducted to record the ecological attributes such as density, frequency, cover, and importance value. These values were then used to calculate the relative values of these ecological indicators. These ecological indicators were correlated with various soil physical parameters (soil texture, moisture contents and saturation percentage), chemical properties (ECe and pH), and nutrients (Na, Ca, K and N). Most of the species were linked to sites 3 and 4 with high moisture content, low ECe, acidic pH and moderate nutrient composition. The species with the highest ecological importance were Cynodon dactylon, Rumex dentatus and Saccharum spontaneum which accounted for more than 80% of the total abundance. It was concluded that species distribution differed significantly along the four study sites mainly depending on the soil-physicochemical features of the study sites.

Dual-Matrix Domain Wall: A Novel Technique for Generating Permutations by QUBO and Ising Models with Quadratic Sizes

The Ising model is defined by an objective function using a quadratic formula of qubit variables. The problem of an Ising model aims to determine the qubit values of the variables that minimize the objective function, and many optimization problems can be reduced to this problem. In this paper, we focus on optimization problems related to permutations, where the goal is to find the optimal permutation out of the n! possible permutations of n elements. To represent these problems as Ising models, a commonly employed approach is to use a kernel that applies one-hot encoding to find any one of the n! permutations as the optimal solution. However, this kernel contains a large number of quadratic terms and high absolute coefficient values. The main contribution of this paper is the introduction of a novel permutation encoding technique called the dual-matrix domain wall, which significantly reduces the number of quadratic terms and the maximum absolute coefficient values in the kernel. Surprisingly, our dual-matrix domain-wall encoding reduces the quadratic term count and maximum absolute coefficient values from n3−n2 and 2n−4 to 6n2−12n+4 and 2, respectively. We also demonstrate the applicability of our encoding technique to partial permutations and Quadratic Unconstrained Binary Optimization (QUBO) models. Furthermore, we discuss a family of permutation problems that can be efficiently implemented using Ising/QUBO models with our dual-matrix domain-wall encoding.

Efficient block contrastive learning via parameter-free meta-node approximation

Contrastive learning has recently achieved remarkable success in many domains including graphs. However contrastive loss, especially for graphs, requires a large number of negative samples which is unscalable and computationally prohibitive with a quadratic time complexity. Sub-sampling is not optimal. Incorrect negative sampling leads to sampling bias. In this work, we propose a meta-node based approximation technique that is (a) simple, (b) canproxy all negative combinations (c) in quadratic cluster size time complexity, (d) at graph level, not node level, and (e) exploit graph sparsity. By replacing node-pairs with additive cluster-pairs, we compute the negatives in cluster-time at graph level. The resulting Proxy approximated meta-node Contrastive (PamC) loss, based on simple optimized GPU operations, captures the full set of negatives, yet is efficient with a linear time complexity. By avoiding sampling, we effectively eliminate sample bias. We meet the criterion for larger number of samples, thus achieving block-contrastiveness, which is proven to outperform pair-wise losses. We use learnt soft cluster assignments for the meta-node construction, and avoid possible heterophily and noise added during edge creation. Theoretically, we show that real world graphs easily satisfy conditions necessary for our approximation. Empirically, we show promising accuracy gains over state-of-the-art graph clustering on 6 benchmarks. Importantly, we gain substantially in efficiency; over 2x reduction in training time and over 5x in GPU memory reduction. Additionally, our embeddings, combined with a single learnt linear transformation, is sufficient for node classification; we achieve state-of-the-art on Citeseer classification benchmark. code:https://github.com/gayanku/PAMC

Assessment of Plants Biodiversity in Innerline Reserve Forest, Hailakandi, Assam, India

The study deals with the “Assessment of Plant biodiversity of Innerline Reserve Forest, Hailakandi (Assam)” India. that was carried out in six sites. A total of 54 species of trees belonging to 32 families with 2,303 individuals, 17 species of shrubs belonging to 13 families with 2,195 individuals and 27 species of grasses and herbs belonging to 13 families with a total of 1,595 individuals were encountered. Quadrate size of 400 m2 for trees, 100 m2 for shrubs, 20 m2 grasses and herbs. Compared to all the six sites, Site-III shows the highest Basal area (243.67 m2). In terms of IVI, Tectona grandis was found to be the most dominant tree species, Clerodendrum infortunatum was found to be the most dominant shrub species and Oplismenus compositus was found to be the most dominant grasses and herb species. In aspects for all the sites it can be concluded that Site-III showed the highest value for Shannon-Weiner Diversity Index (Hˈ) (3.2) for trees species, Site-V showed the highest value for Shannon- Weiner Diversity Index (Hˈ) (2.27) for shrubs species and Site-III showed the highest value for Shannon- Weiner Diversity Index (Hˈ) (2.32) for grass &amp; herb species.

Quadrat misuse: Confessions of a cover crop researcher's biomass sampling journey

AbstractRectangular quadrats (1 m2 or less) are commonly used in cover crop research to sample shoot biomass in fields where the cover crops are planted in narrow rows. However, in drilled cover crops, quadrats do not accurately estimate cover crop biomass unless the width dimension of the quadrat, that runs perpendicular to the rows, is a multiple of the cover crop row spacing. Illustrations are provided with correctly sized and placed quadrats for sampling drilled cover crops along with calculations to convert sampled biomass to field‐scale units. Examples with various quadrat sizes, row spacings, and quadrat placements are used to illustrate how researchers can inadvertently underestimate or overestimate biomass by up to 49% and 27%, respectively. A survey of 92 articles with cover crop biomass data published in the Agronomy Journal and Weed Technology from 2017 to 2021 found that many studies used an incorrect quadrat size, which suggests that they may have inaccurately estimated cover crop biomass. However, assumptions were made to reach this conclusion because only a few papers provided the dimensions, orientation, and shape of the quadrat used. These results (1) raise important questions about possible errors made in papers reporting cover crop biomass data and associated metrics (nitrogen uptake, weed biomass, etc.), and (2) highlight the need for describing sampling methods in greater detail to ensure that accurate data and analysis are published in the literature. Approaches to correct possible errors in published research are described along with biomass sampling suggestions for future cover crop research.

Study of Plant Diversity in Red Sanders Park in Chittoor District of Andhra Pradesh, India

The study deals with the assessment of plant diversity in Red Sanders park in Chittoor district of Andhra Pradesh, India. A total of nine species of trees belonging to six families with 1625 individuals, 25 species of shrubs belonging to 18 families with 2,042 individuals and 40 species of grasses and herbs belonging to 14 families with a total of 1,016 individuals were encountered. Quadrat size of 400 m2 were established for trees, 100 m2 for shrubs, 20 m2 for grasses and herbs. In terms of IVI, Pterocarpus santalinus was found to be the most dominant tree species, chromolaena odorata was found to be the most dominant shrub species and Bothriochloa ischaemumwas found to be the most dominant grasses and herb species. The result of the phytosociological aspects in all four sites concluded that for trees, Site-IV showed the highest value for Shannon-Weiner Diversity Index (H) (1.73). For shrubs, Site-I showed the highest value for Shannon-Weiner Diversity Index (H’) (2.52). For grasses and herb, Site-III had a Shannon-Weiner Diversity Index (Hˈ) of 2.62. The quantitative analysis of diversity and phytosociological attributes of tree species recorded from the present study may provide baseline information for formulating a working plan for conservation and management strategies for the forest.

Soil vegetation status of a forest fragment in Akwa Ibom State, Nigeria

As efforts are geared towards preventing the utter destruction of our ecosystem and ensuring the conservation of our rich biodiversity, adequate quantitative and qualitative ecological data of the flora and fauna species are imperative. Accordingly, the status of phytodiversity and pedological properties were assessed in a tropical forest fragment namely Mkpok Village Forest (MVF) in Akwa Ibom State (AKS). This was with a view to providing insights into its environmental determinants; as well as baseline for the management and conservation of the forest fragment. Systematic sampling method was used to sample the vegetation using a quadrat size of 10 m x 10 m. The frequency, density, height, basal area and crown cover of plant species encountered were determined. Twelve composite soil samples were collected and analyzed for pedological properties (soil pH, texture and chemical constituents) using standard analytical procedures. Forty-two plant species belonging to thirty families were encountered. Family Fabaceae had the highest number of 6 plant species followed by Meliaceae, Arecaceae, and Euphorbiaceae with 3 plant species each. The tallest and shortest tree species were Piptadeniastrum africanum (22.91 ± 2.33 m) and Cannarium schweinfurthii (2.00 ± 0.51 m). Shannon-Wiener and Simpson diversity indices of 2.88 and 0.90 were recorded respectively. Pedological analyses revealed that in MVF the soils were moderately acidic and highly sandy, having low concentrations of some plant nutrients. Correlation analysis indicated relationships between some vegetation parameters and soil chemical constituents (p=0.05). It is concluded that the forest was not structurally complex as expected of a tropical rainforest partly due to anthropogenic activities but possessed attributes of a typical rainforest of Nigeria thus reinforced the hope that this forest fragment if preserved can return to its primary status.

Constructing an Evolutionary Tree and Path–Cycle Graph Evolution along It

The paper solves the problem of constructing an evolutionary tree and the evolution of structures along it. This problem has long been posed and extensively researched; it is formulated and discussed below. As a result, we construct an exact cubic-time algorithm which outputs a tree with the minimum cost of embedding into it and of embedding it into a given network (Theorem 1). We construct an algorithm that outputs a minimum embedding of a tree into a network, taking into account incomplete linear sorting; the algorithm depends linearly on the number of nodes in the network and is exact if the sorting cost is not less than the sum of the duplication cost and the loss cost (Theorem 3). We construct an exact approximately quadratic-time algorithm which, for arbitrary costs of SCJ operations, solves the problem of reconstruction of given structures on any two-star tree (Theorem 4). We construct an exact algorithm which reduced the problem of DCJ reconstruction of given structures on any star to a logarithmic-length sequence of SAT problems, each of them being of approximately quadratic size (Theorem 5). The theorems have rigorous and complete proofs of correctness and complexity of the algorithms, and are accompanied by numerical examples and numerous explanatory illustrations, including flowcharts.

Greenwood regeneration status in community forests of Chiti Lamjung Nepal

Forest regeneration is the process by which new tree seedlings become entrenched after forest trees have been harvested or destroyed by fire, insects, or diseases. The process is key to sustainable forestry and can be accomplished through natural regeneration, which occurs when new seedlings or sprouts are produced by trees left on or near the site. The study is to calculate the regeneration status of the tree species in community-managed forests. The sampling points were generated by using the random table. The sample quadrate size was taken 20m×20m for a tree, 5m×5m for a sapling, and 1m×1m for the seedling. In five community forests, altogether 30 quadrates were taken for a tree, 60 nested quadrates were taken for a sapling and 120 nested quadrates were taken for a seedling. The tree layer, sapling layer and seedling layer were differentiated by taking reference tothe Diameter at Breast Height (DBH) class. An individual having DBH ≥ 5cm is considered a tree, an individual having DBH value between 1cm to &lt; 5cm is considered a sapling, and individuals having 1cm to &lt; 5cm DBH are considered as a seedling. The DBH distribution curve was obtained by plotting diameter class in x- axis and density on y- axis. All studied community forests are mixed forest dominated by tree species Castanopsis indica, Diospyros embryopteris (Diospyros malabarica), Shorea robusta, and Schima wallichii (Schima wallichii choisy). The regeneration potential of the Tilahar community forest(CF) is found high despite high grazing and other human intervention. The DBH class distribution curve of tree species is found as inverse J-shape, indicating that the overall forest has a sustainable regeneration.

Species Composition and Diversity of Tree Species in Nanta Forest Region in Kota District, Rajasthan, India

The objective of this work was to study species composition and diversity of tree species between two vegetation stands, one is a protected vegetation stand and the other is a non-protected vegetation stand. The tree species composition and community structure were analyzed by field visits in Nanta forest region. Random sampling was done by using a standard size of quadrat i.e., 10x10m2. Results showed that a total of 30 species belonging to 25 genera and 11 families are present in the protected site whereas 8 species belonging to 7 genera and 5 families are present in the unprotected site. Anogeissus pendula (Edgew) and Dichrostachys cinerea (L.) were the most important species in protected and non-protected sites respectively. The Simpson’s index is higher in protected vegetation stands showing greater sample diversity. Family Fabaceae is dominant in both the vegetation stand which shows the ecological importance of this family.

VARIATION IN SHORELINE MACROPHYTES AND WATER QUALITY OF BEESHAZARI LAKE, CENTRAL NEPAL

The research has been designed to examine the variation of macrophyte diversity with references to water parameters, which determines the ecological status of Beeshazari Lake (a Ramsar site). Field data were collected in two seasons (monsoon and winter) from 42 plots with 1 m x 1 m quadrat size, laid down at shoreline of the Beeshazari Lake, each plot being 30 m apart from adjacent plot along the lake perimeter for the quantitative analysis of the macrophytes. A total of 42 macrophytes (40 in monsoon and 31 in winter) were recorded during the sampling seasons. Poaceae was the dominant during both seasons, followed by Asteraceae and Euphorbiaceae families during monsoon, whereas Asteraceae and Polygonaceae were found to be dominant during winter seasons. On the basis of growth form, emergent macrophytes were dominant during both seasons. The Shannon-Weiner Diversity Index (SWI) value of macrophytes was higher during the winter (H = 0.98± 0.04) than monsoon (H = 0.97± 0.04). Lemna perpusilla (Importance Value Index, IVI = 22.8) was the dominant species during the monsoon and Azolla pinnata (IVI = 38.2) during the winter. Macrophytes species richness was positively correlated with temperature, pH, DO, and conductivity whereas negatively correlated with TDS during the monsoon season. Further, in the winter season, the richness was positively correlated with pH, DO, TDS, and electric conductivity, whereas negatively correlated with temperature.

A new quadratic asymmetric error correction model: does size matter?

We introduce a new quadratic asymmetric error correction model that comprehensively accounts for both sign and size asymmetries. We also propose a test protocol that allows to rigorously identify different sources of long-run nonlinearity, namely quadratic nonlinearity, size asymmetry and sign asymmetry. We use a nonparametric residual recursive bootstrap technique to report p-values for the long-run tests. Simulation results confirm the consistency of our proposed estimator in finite samples and show that the bootstrapped tests have reasonably good size and power properties. Although our estimation of the Okun’s Law for the USA confirms previous findings on the direction of the sign asymmetry, its reveals that the magnitude of the impact of economic downturns on unemployment decreases faster than the impact of upturns. Forecasting results show that our new model performs better than NARDL.

Determination of Minimum Quadrat Size for Herbaceous Species in Andhra University, Andhra Pradesh, India

In this study we analysed herbaceous species diversity in Andhra University campus by using minimum quadrat size method. For this analysis we used 10 × 10 sq. cm as the minimum size of the quadrat and we gradually increased the quadrate size and the count was repeated each time. We repeated the same procedure for 20 × 20 sq. cm, 30 × 30 sq. cm, 40 × 40 sq. cm and so on till 1 × 1 sq. metre area is covered and we noted the number of additional species every time. The vegetation analysis was carried out by total 10, 1 m × 1m sample plots placed randomly from study area. From the collected data we obtained species-area curve and the curve shows that 80 × 80 sq. cm size is the minimum size of quadrat for herbaceous species diversity analysis in Andhra University, Andhra Pradesh, India.