Size Spectrum Research Articles

The role of mineralogical stratifications in controlling brine flow behavior in shale at a pore-scale perspective based on integrated imaging and compositional methods

Pore-scale multiphase flow has always been a research hotspot petroleum engineering. However, the complexity of pore structure and the variability of the flow process have plagued researchers. More specifically, the controlling mechanisms behind mineral characteristics on brine flow behavior in shale at a pore-scale perspective are not well understood. So far, a limited number of scholars have tried to provide evidence of the underlying mechanisms based on integrated imaging and compositional methods, and the shale classification methods were mainly based on the content variation. This paper provided a new aspect concerning the mineralogical stratifications to investigate the controlling factors of movable fluid properties. Imaging and compositional techniques were used, and the samples with different mineralogical stratifications (inapparent grading sequence shale, apparent grading sequence shale, and microscopic block-shaped shale) were tested. Integrated methods showed that, compared to minerals compositions, the mineralogical stratifications would be more vital for storage capacity and fluid flow behavior in shales. Thick organic minerals bands or chunks would occlude the seepage paths, and pores below 100 nm might be the predominant storage spaces for shales. By combining the results of these methodologies, the pore size spectrum of shales can be determined more accurately. High movable fluid properties were observed for inapparent grading sequence shale. The mechanisms are discussed in terms of mineralogical stratifications and pore networks evolution Low porosity would decrease the movable fluid saturation due to the short storage spaces, and serious mineralogical stratification variations would restrict the flow path, leading to weak mobility of brine.

A Detailed Ecological Exploration of the Distribution Patterns of Wild Poaceae from the Jhelum District (Punjab), Pakistan

The purpose of this study was to investigate the taxonomic diversity, richness, and distribution patterns of Poaceae in relation to abiotic factors in the Jhelum district of the Pakistan Himalayas. We used a random sampling technique from 80 grids within 240 sites with a rich diversity of wild grasses and 720 quadrates in triplets from each site across the Jhelum district between 2019 and 2021 to collect data on grass species and the associated environmental factors and conditions. After evaluating the important value index for each plant taxa and for the environmental data, we analyzed the data using ordination and cluster analysis techniques. Fifty-two Poaceae taxa from twenty-nine genera were recorded within the study area. From a total of 52 recorded Poaceae species, 45 were native and 7 were invasive species. The life form (biological) showed the dominancy of 27 therophyte species, followed by 24 hemicryptophyte species, and 1 geophyte species. Microphyll had the leading leaf size spectra (27 species), followed by nanophyll (12 species), macrophyll (10 species), and leptophyll (3 species). The trend of the life cycle was the maximum (27 spp.) during the monsoon season, followed by spring (11 spp.), winter (8 spp.), and summer (6 spp.). The leading genera were Setaria with 9.61% of the species, followed by Panicum, Cenchrus, and Brachiaria with 7.69% of the species. Aristida and Echinochloa made up 5.76% of the species while Chrysopogon, Digitaria, Eragrostis, Pennisetum, and Poa made up 3.84% of the species. Other genera recorded single species. The leaf size spectra of grasses were dominated by microphylls (50%) followed by nanophylls (23.07%), macrophylls (19.23%), and leptophylls (7.69%). On the basis of the importance value index, the most dominant species was Cynodon dactylon (68), followed by Dichanthium annulatum (58), Brachiaria ramose (38), Dactyloctenium aegyptium (37), Eleusine indica (35), Saccharum bengalense (33), and Cenchrus biflorus (28). Two-way cluster analyses classified the grasses into three plant community associations based on the indicator plant species. Soil parameters as subsamples were tested for moisture, pH, EC, OM, macronutrients (CaCO3, N, P, and K), and saturation while the ordination analysis revealed that they had a significant (p ≤ 0.002) effect on vegetation associations. Overall, this study contributes to a better understanding of the influence of environmental factors on the composition and associations of grass species and the development of scientifically informed management solutions for the ecological restoration of degraded habitats in this Himalayan region.

Phytoplankton and particle size spectra indicate intense mixotrophic dinoflagellates grazing from summer to winter.

Mixotrophic dinoflagellates (MTD) are a diverse group of organisms often responsible for the formation of harmful algal blooms. However, the development of dinoflagellate blooms and their effects on the plankton community are still not well explored. Here we relate the species succession of MTD with parallel changes of phytoplankton size spectra during periods of MTD dominance. We used FlowCAM analysis to acquire size spectra in the range 2–200 μm every one or two weeks from July to December 2007 at Helgoland Roads (Southern North Sea). Most size spectra of dinoflagellates were bimodal, whereas for other groups, e.g. diatoms and autotrophic flagellates, the spectra were unimodal, which indicates different resource use strategies of autotrophs and mixotrophs. The biomass lost in the size spectrum correlates with the potential grazing pressure of MTD. Based on size-based analysis of trophic linkages, we suggest that mixotrophy, including detritivory, drives species succession and facilitates the formation of bimodal size spectra. Bimodality in particular indicates niche differentiation through grazing of large MTD on smaller MTD. Phagotrophy of larger MTD may exceed one of the smaller MTD since larger prey was more abundant than smaller prey. Under strong light limitation, a usually overlooked refuge strategy may derive from detritivory. The critical role of trophic links of MTD as a central component of the plankton community may guide future observational and theoretical research.

The mechanics of acoustic signal evolution in field crickets.

Field crickets (Family Gryllidae, Subfamily Gryllinae) typically produce tonal calls with carrier frequencies in the range 3-8 kHz. In this study, we explored the use of a finite element model (FEM) of the stridulatory apparatus of a field cricket, Gryllus bimaculatus, based on experimental measurements of resonator geometry and mechanical properties, to predict the measured call carrier frequencies of eight other field cricket species, ranging between 3 and 7 kHz. The model allowed accurate predictions of carrier frequencies for all eight species to within a few hundred hertz from morphological measurements of their resonators. We then used the model to explore the plausible evolutionary design space for field cricket call carrier frequency along the axes of resonator size and thickness, and mapped the locations of the nine experimentally measured species in this design space. Although the nine species spanned the evolutionarily conserved spectrum of carrier frequency and body size in field crickets, they were clustered in a small region of the available design space. We then explored the reasons for this apparent evolutionary constraint on field cricket carrier frequencies at both the lower and higher limit. We found that body size and sound radiation efficiency were the main constraints at the lower limits, whereas the energetics of stridulation using the clockwork mechanism may pose a constraint at higher frequencies.

Multidecadal changes in the demersal community structure in an urban bay: Shift from a bottom- to a top-heavy pyramid

Fish community structures in urban bays have changed over time as a result of anthropogenic activities, leading to changes in species richness, diversity, fish assemblage composition, and abundance. Tokyo Bay is one of the most eutrophic urban bays in Japan, and hypoxia occurs every summer in the bottom water of the bay. Accordingly, the demersal community in the bay has undergone drastic changes in taxonomic composition over the past several decades. We analyzed data from a bottom trawl survey spanning 35 years to characterize multidecadal changes in the slopes of body size spectra of the demersal community in Tokyo Bay, as a reliable index to represent shifts in community structure. We found that the community shifted from bottom-heavy pyramids in the past (1977–1995) to top-heavy pyramids in recent years (2003–2019) due to a decrease in the biomass of small-sized crustaceans and an increase in the biomass of large-sized elasmobranchs. Human-induced hypoxia can promote the formation of top-heavy pyramids, as it decimates the number of small-sized individuals. The existence of energy subsidies to large-sized individuals from the inner-shallow and outer bay areas as well as the pelagic community provides a possible explanation for the persistence of top-heavy pyramids.

Early Holocene palaeoceanographic and glaciological changes in southeast Greenland

Sediment core ER11-16 from Køge Bugt in Southeast Greenland is used to assess early Holocene palaeoceanographic changes and sediment rafting from icebergs calved from the large outlet glaciers in the area. Diatom analysis reconstructs variability in surface water temperature, salinity and sea-ice concentrations, and benthic foraminiferal assemblages is used to reconstruct subsurface ocean conditions. We report Holocene Thermal Maximum in Southeast Greenland during the early Holocene (at least since onset of the record 9100 cal yr BP) until around 4500 cal yr BP, which contrasts with a delay until the mid-Holocene of the Holocene Thermal Maximum in South and Southwest Greenland. The early Holocene warming in Southeast Greenland was caused by a combination of high solar insolation and a weakened subpolar gyre, both of which served to warm the Irminger Current waters subducting onto the shelf. At the same time, the surface temperature was relatively high and sea-ice cover in the polar surface waters of the East Greenland Current was relatively low. High levels of iceberg rafting occurred in Køge Bugt during the early Holocene, synchronously with these warm oceanic temperatures. This is attributed to an increase in iceberg production from the extensive, but retreating, Greenland Ice Sheet. The warm surface conditions were interrupted by a marked and short-lived increase in sea ice around 8200 years ago, providing the first evidence of this global cold episode in Southeast Greenland. After 4500 cal. yr BP, sea-ice cover increased with an expansion of the East Greenland Current, suppressing the inflow of warmer subsurface Irminger Current water to the Southeast Greenland shelf. We relate this oceanic shift to the decreased Northern Hemisphere summer solar insolation. Multi-centennial variability is observed in the grain size spectrum of iceberg rafted debris; a finding we interpret in the context of palaeoceanographic changes.

ВЛИЯНИЕ СИЛЬНОГО АЭРОЗОЛЬНОГО ЗАГРЯЗНЕНИЯ ВОЗДУХА НА ЭВОЛЮЦИЮ КОНВЕКТИВНЫХ ОБЛАКОВ ВО ВРЕМЯ ГРОЗЫ В КИТАЕ ПО РЕЗУЛЬТАТАМ ТРЕХМЕРНОГО ЧИСЛЕННОГО МОДЕЛИРОВАНИЯ

Numerical simulation of evolution of a convective cloud and precipitation during a thunderstorm event that took place on August 11, 2017 in Beijing (China) against a background of high aerosol air pollution was performed using a numerical nonstationary three-dimensional model. Different microphysical parameters of drops and ice particles which depend on aerosol pollution of the atmosphere, were varied: an autoconversion threshold for cloud droplets and raindrops and parameters of raindrop and hailstone size distribution. It was found for this case that liquid drops do not play a significant role in the convective cloud evolution. The effect of aerosol pollution both on the raindrop size spectrum and on the transition of cloud droplets to raindrops does not influence significantly dynamic, microphysical and electrical properties of the cloud. At the same time, the change in the ice particle spectrum towards the size decrease that happens under the influence of increased aerosol pollution, has a significant impact on the evolution of the cloud and precipitation. The amount of precipitation decreases both within the cloud and on the underlying surface. However, the lightning activity of the cloud changes little

Aquatic macrophyte fluctuations since the 1900s in the third largest Chinese freshwater lake (Lake Taihu): Evidences, drivers and management implications

Diverse aquatic macrophyte communities represent an essential component of healthy shallow lake ecosystems, and information on changes in macrophytes abundance and composition is crucial for restoration initiatives and management. However, the long-term dynamics of aquatic macrophyte communities are poorly understood for most subtropical freshwater lakes. This study used macrophyte surveys from 1960 to 2014 alongside plant macrofossil and pollen remains deposited in the sediment to reconstruct, macrophyte community change over the two centuries in the southeastern bay of Lake Taihu, China. Plant macrofossils efficiently captured the main historical recorded macrophyte species, including four unrecorded submerged taxa (Vallisneria spinulosa, Zannichellia palustris, Nitella sp., and Chara sp.) by the monitoring surveys. Aquatic pollen failed to reflect the main species composition in the bay, but provided additional information on species with no macrofossils and few seeds, especially the floating-leaved and free-floating taxa (e.g., Nymphoides and Azolla). We conducted a constrained incremental sum of squares cluster analysis and a multiple factor analysis (MFA) to the macrophyte community in the core and identified three major changes over the past century, with a shift from Potamogeton malaianus (pre-1960), to Vallisneria natans, P. malaianus, Potamogeton maackianus, and charophyte species (1960–1998), followed by the proliferation of pollutant-resistant species Ceratophyllum demersum and Myriophyllum spicatum, as well as the floating-leaved plant Nymphoides (post-1998). MFA also clearly elucidated the relationships between macrophyte shifts and changes in various environmental stressors (i.e., cladocerans, particle size spectra and geochemical data). The results confirmed our hypothesis, which stated that hydrological alterations and increased nutrient inputs, driven by the increasing anthropogenic pressures were likely the main drivers of the alteration in the macrophyte composition and succession in the bay. Our study provides a unique perspective on the pre-disturbance macrophyte community composition of Eastern Lake Taihu, thereby offering useful information not only for lake managers in the Yangtze region, but also for the global decision-making for the eutrophication and restoration of large shallow lakes.

Zooplankton Size Structure in Relation to Environmental Factors in the Xiangxi Bay of Three Gorges Reservoir, China

Body size is sensitive to environmental changes and one of the fundamental traits linking ecological functions. Size structure has been suggested as a useful indicator for environmental monitoring and assessment in aquatic ecosystems. However, the organisms’ size structure and the relationship with environmental factors remain seldom addressed in reservoir ecosystems. In this study, we investigated the size spectrum, size diversity of the zooplankton and their relationships with environmental conditions across nitrogen and phosphorus gradients in the Xiangxi Bay of Three Gorges Reservoir, China. We further tested the hypotheses that how nutrient and water temperature affect zooplankton size structure: nutrients indirectly affect zooplankton size spectrum and size diversity via phytoplankton (H1); increasing water temperature will reduce size diversity and result in a steeper size spectrum (H2); size diversity is a more robust metric indicating environment changes than the size spectrum in high dynamic ecosystems (H3). We found that both the size spectrum and size diversity showed high spatiotemporal dynamics. The size spectrum ranged from −3.373 to −0.984. The size diversity ranged from 0.631 to 3.291. Spatially, the lowest values of the size spectrum and size diversity were observed in the upstream areas of Xiangxi Bay, where nitrogen and phosphorus concentrations are high and low, respectively. And in temporal dynamics, lower values of the size spectrum and size diversity were generally observed in March and April. Further analyses based on the structural equation model (SEM) found a clear pathway revealing that nutrient variables affect the zooplankton abundance and size structure, supporting hypothesis H1. That is, dissolved inorganic nitrogen had an indirect effect on the zooplankton abundance, size spectrum, and size diversity by influencing the concentration of phytoplankton chlorophyll a. In addition, results of SEM suggested that increased water temperature had a significant negative effect on the size diversity but had non-significant effects on zooplankton abundance and size spectrum. This finding suggests that size diversity is a reliable and useful index in measuring the zooplankton size structure in reservoir ecosystems with high dynamics, which may have a wide application in environmental monitoring and assessment, especially for complex and dynamic aquatic ecosystems.

Evaluation of advanced accumulator in a VVER-1000 reactor in loss of coolant accident

The advanced accumulator is a passive system which gradually decreases the high flow into a low flow. The role of the fluidic device is to obtain an additional safety margin by increasing golden time to cope in the LOCA. In this paper, the effect of using the safety injection tank and the fluidic device, called advanced accumulator, in a wide spectrum of LOCA break sizes without emergency core cooling systems (ECCS) of a VVER-1000 is evaluated. Firstly, the main component of primary and secondary loops of Bushehr nuclear power plant (BNPP) is modeled by RELAP5. Secondly, the performance of the model is assessed in steady-state and LOCA conditions by comparing the obtained results with the plant’s FSAR. Thirdly, a model is developed in RELAP5 to simulate the behavior of advanced accumulator and validated by blowdown test in a test facility and MARS-KS code. Finally, the performance of advanced accumulator in the spectrum of 200–300 mm break sizes of LOCA without ECCS. In this range of breaks, the core damage times (CDT) developed from peak cladding temperature (PCT) of 1204 °C have been calculated. In accordance with the results, the advanced accumulators can increase the CDT in the whole range of breaks.

Using femtosecond laser pulses to investigate the nonlinear optical properties of silver nanoparticles colloids in distilled water synthesized by laser ablation

The nonlinear optical properties of silver nanoparticles (AgNPs) colloids in distilled water, when irradiated with 100 fs laser pulses, were investigated experimentally using the Z-scan technique. At a constant wavelength of 760 nm and different excitation powers, the nonlinear absorption coefficient and nonlinear refractive index were measured. The AgNPs colloids are synthesized by laser ablation of silver bulk in distilled water using a 532 nm Nd: YAG laser with different ablation energies fluence of 9, 15.5, and 26 ⨯104 (J/cm2) over a 30min ablation time. The nanoparticle size, shape, and absorption spectra of nanoparticle colloids were determined using transmission electron microscopy and an ultraviolet–visible spectrophotometer. Spherical AgNPs are formed with an average diameter ranging from 7.5 to 12 nm. As the laser ablation energy fluence increases, the average size of the AgNPs decreases while the bandgap energy increases. As the excitation laser power and AgNPs size increase, the nonlinear absorption coefficient and nonlinear refractive index decrease. The optical limiting performance of AgNPs improves with increasing laser ablation energy fluence, with the best performance at 26⨯104 (J/cm2).

Synthesis mechanisms and effects of BaTiO3 doping on the optical properties of Bi0.5Na0.5TiO3 lead-free ceramics

Research in (1-x)Bi0.5Na0.5TiO3-xBaTiO3, (x ​= ​0.01 to 0.09), (known as BNT-BT) perovskite materials ranges from fundamental scientific analysis like crystal structure, optical and electrical properties to technologies for advanced energy storage batteries, low-power electronics, sensors, and energy conversion devices. The properties observed in this versatile materials class originate, in part, from the ability to connect crystallographic structures with several applications. The aim of this review article is the emerging technologies in BNT-BT materials by several syntheses aimed to reach unexplored portions of the crystallographic structure with optical property for rational materials design. The four chemistry dependent strategies have been reviewed: crystal structure with the domain-super lattice, synthesis routes, comparison of particle size, microstructure and Raman spectra. Finally, this article touches on the new functionalities of BNT-BT that the material could attain through external applications and highlight unresolved problems.

Assessing the size spectra of marine fish communities with hydroacoustics: examining the challenges of abundant schools, diverse assemblages, and variable orientations

Assessing marine fish community size spectra with hydroacoustics is challenging, as communities are diverse, schooling and swim-bladder-less fishes are common, and fish orientation is variable. We developed an approach to examine these challenges and applied it to data from 51 optic–acoustic surveys of fishes at petroleum platforms throughout the US Gulf of Mexico. When in situ target strength (TS; dB re 1 m2) distributions were used to calculate the density (and subsequently abundance) of schooling fishes, fish lengths and size spectra slopes were significantly smaller than in simulated communities and fish community censuses at platforms (i.e., reference datasets). However, acoustic slopes were comparable to reference slopes when simulated TS values (based on species composition) were used to calculate schooling fish abundance. These findings held regardless of whether specific or general models were used to convert TS to length. Fish orientation was not a useful predictor of TS or slope, but may explain why in situ TS measurements from small groups of fishes around schools were unsuitable for abundance calculations. By examining the challenges associated with assessing size spectra with acoustics, this study aids progress towards using acoustic size spectra metrics for ecological inferences.

Bivalve body-size distribution through the Late Triassic mass extinction event

AbstractThe synergic relationship between physiology, ecology, and evolutionary process makes the body-size distribution (BSD) an essential component of the community ecology. Body size is highly susceptible to environmental change, and extreme upheavals, such as during a mass extinction event, could exert drastic changes on a taxon's BSD. It has been hypothesized that the Late Triassic mass extinction event (LTE) was triggered by intense global warming, linked to massive volcanic activity associated with the Central Atlantic Magmatic Province. We test the effects of the LTE on the BSD of fossil bivalve assemblages from three study sites spanning the Triassic/Jurassic boundary in the United Kingdom. Our results show that the effects of the LTE were rapid and synchronous across sites, and the BSDs of the bivalves record drastic changes associated with species turnover. No phylogenetic signal of size selectivity was recorded, although semi-infaunal species were apparently most susceptible to change. Each size class had the same likelihood of extinction during the LTE, which resulted in a platykurtic BSD with negative skew. The immediate postextinction assemblage exhibits a leptokurtic BSD, although with negative skew, wherein surviving species and newly appearing small-sized colonizers exhibit body sizes near the modal size. Recovery was relatively rapid (~100 kyr), and larger bivalves began to appear during the pre-Planorbis Zone, despite recurrent dysoxic/anoxic conditions. This study demonstrates how a mass extinction acts across the size spectrum in bivalves and shows how BSDs emerge from evolutionary and ecological processes.

Synthetic Mechanism of UiO‐66‐NH2/BiVO4/BiOBr Spherical and Lamellar Dual Z‐scheme Heterojunction and Efficient Photocatalytic Degradation of Tetracycline Under Visible Light

AbstractIn order to solve antibiotic pollution, it is necessary to design photocatalysts with high specific surface area and efficient electron transfer performance. In this study, we report that two‐dimensional (2D) BiVO4/BiOBr flakes were anchored on the smooth surface of UIO‐66‐NH2 using a two‐step solvothermal‐hydrothermal approach, which forms the dual Z‐scheme mechanism and has rich specific surface area (306.5 m2/g), uniform particle size (2.05 nm) and wide absorption spectrum (2.76 eV). It shows 89.56 % tetracycline (TC) degradation efficiency within 180 min under visible light illumination due to the excellent adsorption properties and ample active sites. This work provides an effective strategy for designing a novel ternary photocatalyst to the degradation of refractory organic pollutants.

Patient-Centered Care for Obesity: How Health Care Providers Can Treat Obesity While Actively Addressing Weight Stigma and Eating Disorder Risk

Patient-Centered Care for Obesity: How Health Care Providers Can Treat Obesity While Actively Addressing Weight Stigma and Eating Disorder Risk

A generalized solution to the combo-crack problem—I. Pressure load on crack surface

The axisymmetric elasticity problem of crack combo containing an externally circular crack (ECC) and a coplanar concentric penny-shaped crack (PSC) is mathematically equivalent to the annular contact problem. This problem has been attempted by using Love's strain potential approach, which eventually comes down to solving a pair of simultaneous Fredholm integral equations. Finding the closed-form solutions to the integral equations is difficult, if not impossible. Approximate solutions have been proposed in power series representations, which suffer from two major deficiencies. First, the solutions apply only to a special loading case in which uniform pressure is applied to the whole surface of the interior PSC. Secondly, the accuracy of the solution becomes unsatisfactory when the interior PSC tip is close to the ECC tip. To address these issues, in this paper we revisit this problem by considering a more general loading case in which uniform pressure is applied to a circular region of any size at the center of the PSC's surface. To overcome the lower accuracy caused by power series with limited terms, we numerically solve the pair of simultaneous Fredholm integral equations based on the Gauss-Lobatto quadrature. The high accuracy of our solution in the whole size spectra of the PSC and ECC is verified by finite element simulations. Our paper provides a generalized and more accurate solution to the annular contact problem or the combo crack problem, which deserves to be included in the updated library of the solutions to basic crack problems.

The effect of niche filtering on plant species abundance in temperate grassland communities

Abstract Niche filtering predicts that abundant species in communities have similar traits that are suitable for the environment. However, niche filtering can operate on distinct axes of trait variation in response to different ecological conditions. Here, we use a trait‐based approach to infer niche filtering processes and (a) test if abundant and rare species in grassland communities are differently positioned along distinct axes of trait variation, (b) determine if these trait variation axes, as well as phylogenetic and functional similarities, drive species relative abundance (above‐ground cover) within communities, and (c) explore whether these relationships vary across grassland types and macro‐climatic gradients. We analysed species abundance in vegetation plots from temperate grasslands in Central Europe as a function of species position along three axes of trait variation: the ‘Plant Size Spectrum’ (PSS), the ‘Leaf Economics Spectrum’ (LES) and the ‘Life span/Clonality Spectrum’ (LCS). We also used phylogenetic and functional similarities in the multi‐dimensional trait space as predictors of species abundance. We compared our results among alpine, wet, mesic and dry grasslands and tested whether the effect of the predictors on species abundance was significant across macro‐climatic gradients. Compared to abundant species, rare species in grassland communities were more commonly annual and non‐clonal, had lower stature and smaller leaves and seeds, and relied on more acquisitive leaf economics. Our predictors significantly explained species abundance in approximately one‐third of the plots. LES was the most important predictor across all plots, with the most prominent effect in alpine and dry grasslands and areas with more extreme temperatures. In contrast, in mesic and wet grasslands and grasslands located in warmer and less seasonal regions, species abundance was best predicted by phylogenetic similarities between species, with Poaceae species becoming more abundant. Our study explored trait–abundance relationships for different community types across a large area and broad macro‐climatic gradients. We conclude that niche filtering, and particularly resource‐acquisition trade‐offs, drives species abundance in temperate grassland communities of Central Europe. Our findings emphasize the interaction between local environmental conditions and plant function in determining community assembly. A free Plain Language Summary can be found within the Supporting Information of this article.

Selected aspects of indirect R&D support in the Czech Republic

Sustainable economic development and current global challenges accentuate businesses’ innovative activities across the size spectrum. Developed countries are looking for ways to support the acceleration of R&D activities. A mix of direct and indirect instruments is used for this purpose. Indirect instruments are implemented in the corporate environment primarily through various tax incentives. A widespread form of tax incentives represents the possibility of reducing the tax base by expenses related to R&D activities. The article analyses the amount and structure of companies in the Czech Republic, which use the deduction for research and development. The research sample includes all companies that filled out their tax returns between 2009 and 2020. The established hypotheses are tested using the methods of descriptive statistics, the Chi-Square test of independence, and the analysis of variance. The research results confirm a statistically significant difference between the average number of companies using deduction for research and development if those companies are classified according to their size. In addition, it was revealed that the number of companies using deduction for research and development has gradually declined since 2015. Furthermore, it was found that the structure of companies using the deduction for research and development changes over time.

竞争-耐胁迫-杂草型植物对策理论及其应用研究进展

竞争-耐胁迫-杂草型植物（CSR）对策理论主要研究植物对环境胁迫和干扰的适应性特化。从功能生态学角度讲，CSR理论是通过解释各种功能性状协同变异的主导维度来反映植物的生态对策。而物种所采取的生态对策将决定其在群落中的生态位，并最终会影响生态系统过程与功能。自1974年Grime首次提出CSR对策的概念以来，CSR对策思想就受到了生态学家很大的关注，经过近半个世纪的发展，目前已经形成了比较完整的理论和研究方法体系。试图在回顾CSR理论及其研究方法发展的基础上，阐述其基本内涵，并重点从功能性状变异空间、植物适应性、群落过程和生态系统特性等4个方面概述CSR理论及其分析模型的验证及应用，梳理其最新研究进展。CSR理论已经得到了很多研究的广泛验证并应用于多种尺度上的植物生态学研究，但仍有一些方面值得进一步发展完善，如第四区缺失问题、功能性状变异主轴以外的变异、CSR对策与功能性状种内变异和谱系关系的联系等方面需要深入研究。;Competitor, stress-tolerator, ruderal (CSR) theory, regarded as one of the best developed plant ecological strategy schemes, mainly studies the adaptive specialisation that plants evolve to achieve fitness in response to natural selection pressures, resulting in a triangular distribution of species optima along axes of habitat productivity and disturbance. From the perspective of functional ecology, the CSR theory reflects plant ecological strategies by explaining the principal functional spectra in the multidimensional trait space, that is, the world-wide economics spectrum and the size spectrum as fundamental gradients of plant evolution are major components of the CSR strategy variation. The ecological strategies adopted by plants then determine their ecological niche in the community and ultimately affect ecosystem processes and functions. Thus the CSR theory could not only be used as a framework for functionally classifying plants and predicting impacts of environmental change on vegetation, but also serves as a conceptual framework for investigating and interpreting community processes and ecosystem functioning. Since the concept of CSR strategies was first raised by Grime in 1974, the idea of CSR strategies has attracted much attention from ecologists, and the CSR theory has formed a relatively complete system of theories and research methods over the last half century. In this paper, we introduce the development and characteristics of the CSR theory and its methods to expound the core philosophy of the theory, review the verification and application of the CSR theory and its models by addressing the relevance of CSR strategies to functional trait variations, species adaptation, community processes and ecosystem properties, and summarize the advances in this theory. The CSR theory has been extensively validated by many studies and widely applied as a very useful analysis tool to plant ecology research on a variety of scales, but it needs further research, such as the missing fourth corner in the Grime's C-S-R triangular model, the rest functional variations beyond the principally functional trait spectra that are not explained by the CSR scheme, and the relationships between CSR strategies and the intraspecific trait variation and phylogenetic signal. Especially for the rest functional variations, the CSR theory does not preclude the existence of additional axes of variability subordinate to the principal functional spectra, nor that these may be certainly key to fitness and survival in specific cases. The CSR theory could be seen as a general adaptive strategy, since it is consistent with economics and size tradeoffs evident throughout the tree of life, hinting at overarching natural selection filters operating universally within the biosphere.