The concentration of power in the market for contemporary art: an empirical analysis of ArtReview’s “Power 100”

Art experts and intermediaries play a crucial role in art markets. Artworks are goods whose quality is difficult to determine. Therefore, it seems necessary to restrict competition in the market for art experts to a certain extent, but not too much, in order to provide high-quality know-how. This paper contains an empirical analysis of the extent to which the market for art experts is concentrated. To this end, different methods for measuring the market concentration are applied, with an emphasis on the determination of the distribution function of a newly defined Power Index. The annual Power 100 ranking in the magazine ArtReview from 2002 to 2019 is used to study concentration in the art expert market. The results reveal not only several indications of a hierarchically tiered, but also highly concentrated market power in this market. First, the selection of nationalities of the so-called power members is biased, given that particularly Americans and western Europeans are overrepresented in relation to their world population shares, in contrast to underrepresented Asians, Africans, and Latin Americans. Second, although there is considerable variability in the low tiers of the ranking, the top positions in the rankings are very stable, as shown by the Power Dominance Index. Third, the main empirical result of this paper is that the Top 99 ranking positions follow an extreme value Fréchet distribution with a fat tail. This is interpreted as an indication of excessive concentration on the highest tier of art experts. Liberalizing the art expert market to a certain extent may provide more diversity and less dominance in high-end art markets.

The structure community of zooplankton and environmental conditions of the Kalimireng River estuary, Gresik, East Java

Water quality monitoring is a key component in the management of these important water resources and ecosystems. Biological indicators can be monitored continuously and are easy instructions for monitoring the occurrence of pollution. One of the biological parameters that can be used as a marker of environmental conditions is plankton. zooplankton can be used as study material to determine the quality and water productivity. The method used in this research is descriptive to determine the water quality condition in the estuary of the Kalimireng river biologically through the identification and characterization of zooplankton. Observations of plankton identification, plankton abundance, dominance index, and characterization of zooplankton were analyzed by fluorescence microscope observation. Three species of zooplankton were found in the waters of the Kalimireng estuary, Leptodiaptomus sp., Canthocamptus staphylinus, and Diaphanosoma bracyurum. Zooplankton is more abundant in water conditions at high tide compared to water conditions at low tide. At high tide, the highest abundance value was obtained at the station I at week 3, 843 ind/mL. At low tide, the highest abundance value was obtained at the station I at week 2,251 ind/L. The highest Dominance Index (D) at tidal water conditions is shown at station 2. This indicates that there is a community that dominates at that station.

Biodiversity And Arthropod Abundance In Organic Semi Rice In Swamp Lowland in Palangka Raya City

Palangka Raya has the potential for swamp lowland to be used for rice farming. For this purpose, knowledge of arthropod biodiversity is required. The study aims to determine the biodiversity and abundance of arthropods and arthropods dominant in semi-organic rice plantations in swamp lowlands. The study was conducted from September to November 2019 in Palangka Raya City. The study was carried out on 1.148m2 farmer's paddy fields. The land is divided into three trial plots, each measuring 28x13 m2. Observations were made at the age of 8-15 WAP. Samples were taken using a net trap (Sweep net). Arthropod biodiversity was analyzed using the Shannon-Weaver diversity index (H'). The results showed that in the semi-organic rice ecosystem were obtained 10 orders, 58 families with a total of 8973 individuals, consisting of pests 92.61%, predators 6.59%, parasitoids 0.28%, pollinators 0.06%, Detrivore 0.35%, and 0.07% neutral insects. Diversity index (H') is low to moderate (0.10-2.19), dominance index (C) is in the low to high (0.18-0.97); Evenness index shows that the community is depressed until unstable (0.04-0.67); and The abundance index on the criteria of less to very much (8.96-25.03). The dominant arthropods are dominated by the Rice bug (Leptocorisa acuta).

KEANEKARAGAMAN JAMUR MAKROSKOPIS DI KAWASAN AIR TERJUN CURUG EMBUN KOTA LUBUKLINGGAU

This study aims to determine the types, diversity index, species evenness index, dominance index, and relative density of macroscopic fungi in the Waterfall area of ​​Curug Embun, Marga Bakti Village, North Lubuklinggau District I. This research is quantitative descriptive. Data collection techniques in this study using the roaming method with sampling using purposive sampling technique. The results of the analysis of the macroscopic fungal diversity index in the Curug Embun Waterfall area were 1.3530, the species evenness index was 0.4516, the dominance index was 0.4776 and the highest relative density was 68.027%. There are 3 edible species and 17 non-edible mushrooms. 17 species of macroscopic mushrooms in the Waterfall area of ​​Curug Embun were found. The diversity index, dominance, and Simpson index are in the medium category. Schizophyllum commune is the most commonly found species.

KEANEKARAGAMAN TUMBUHAN PAKU DI BUKIT BOTAK KABUPATEN MUSI RAWAS SUMATERA SELATAN

This study aimed to determine the types of Pteridophyta and to determine the index of diversity, dominance, and evenness in the Botak Hill. The research method used is descriptive quantitative. The data collection techniques in this study were exploratory methods and purposive sampling techniques. Based on the results of the study found as many as 1620 individual, consist of 24 species, 16 genera, 8 families and 4 orders. The results of the analysis of the diversity index of 2.851 (medium category), the dominance index value of 0.06 (low category), the evenness index of 0.679 (high category). There were 24 species of ferns found in Botak Hill, diversity was in the medium category, dominance was in the medium category and evenness was in the high category.

Study of Fish Community in Ulak Lia Lake Sekayu, Musi Banyuasin Regency

This study aims to determine fish's diversity, abundance, and dominance in Ulak Lia Lake, Sekayu District. This research was conducted at Lake Ulak Lia, Sekayu District, Musi Banyuasin Regency, from February to March 2021. The fish sampling method was performed by direct catching at three predetermined observation stations using nets. Netting was carried out for 12 hours, taking catches with traps that have been installed in the morning from 7 a.m. to 9 a.m., depending on conditions or weather. Sampling was marked using a bamboo buffer and the help of the Global Positioning System (GPS). The results showed that the Diversity Index ranged from 1.85 to 1.91 indicating low diversity. The fish abundance index ranged from 30.16 to 36.87 indicating low fish abundance. Where the Dominance Index 0.71-0.72 shows a moderate dominance index. Meanwhile, the dominant fish in Ulak Lia Lake is the Sapil fish (Helostoma temminckii).

Changes in Habitat Conditions of Invaded Forest Communities in Podunajská Nížina and the Impact of Non-Native Species on Biodiversity (SW Slovakia)

With the phytocenological research of riparian mixed forests and pannonic woods in the Podunajská nížina in 2018 and 2019, we obtained 113 phytocenological relevés of invaded and non-invaded stands. Using the Modified Permutation Test, we derived modified Ellenberg indication values (EIVs) in order to determine statistically significant differences and correlation relationships between diversity indices and EIVs. We recorded 15 invasive species in the stands, for example, Ailanthus altissima, Ambrosia artemisiifolia, Asclepias syriaca, Aster lanceolatus, Helianthus tuberosus, Impatiens parviflora, Negundo aceroides, Solidago canadensis, S. gigantea and Robinia pseudoacacia. We also confirmed the occurrence of species important for conservation: Epipactis helleborine agg., E. voethii, Cephalanthera longifolia, Clematis integrifolia and the like. We tested the statistical significance of EIVs as explanatory variables by redundancy analysis and Monte Carlo permutation test (stepwise selection, number of permutations 499, p < 0.05). In addition to the EIV continentality, the contribution of light, moisture, nutrients, soil reaction and temperature was higher than random. The model explains 20.21% of the variability pursuant to the coefficient of determination (R 2), with its adjusted (more accurate) variant (R 2 adj) capturing 15.70% of the variability of the model. Using the Kruskal–Wallis test, we confirmed the statistically significant differences (p*) in mean values between count of species, Shannon–Wiener index, Simpson dominance index and taxonomic diversity of invaded and non-invaded vegetation. For EIVs, we found significant differences in the mean values for moisture and soil reaction factors. In our model, count of species, Shannon–Wiener index, Simpson dominance index and taxonomic diversity index were positively correlated with invaded stands. Non-invaded stands showed statistically significant negative correlation with the EIVs moisture, soil reaction and nutrients. Biotic indices are appropriate and sensitive metrics for assessing the rate of community invasion. Lowland riparian forests are dynamic ecosystems through the structure of their stands and the dynamics of the nutrient and energy cycle of the river landscape. After disturbance (fire, wind, logging), the high degree of invasibility makes them vulnerable to the infiltration and spread of non-native species, which is a problem, especially in protected areas.

Combined application of animal manure and straw benefit soil fauna community in dryland farming

Addition of organic wastes such as animal manures and straw is a feasible practice to alleviate soil degradation, and the mitigation is closely related to the activities of soil-dwelling fauna. In this study, the community structure of soil fauna were compared under four treatment regimes: straw only, and straw combined with the use of chicken manure, ox manure and pig manure. A total of 12459 soil fauna were captured, belonging to 23 groups. Treatments animal manure combined with straw led to increased the number of soil fauna groups and individuals, diversity index, richness index and dominance index, while reduced the evenness index of soil fauna. Compared to the other treatments, maize straw plus chicken manure and maize straw plus pig manure treatments had the largest number of soil fauna groups. Among all the treatments, Oribatida, Astigmata, Desoria and Folsomia were the dominant species, accounting for 69.94 % of the total number of individuals. Maize straw plus pig manure treatment had the largest diversity index soil fauna community. The richness index of soil fauna community in maize straw plus chicken manure and maize straw plus pig manure treatments were higher compared to other treatments. The highest dominance index of soil fauna was recorded in maize straw plus ox manure treatment. In conclusion, our findings suggested that animal manure combined with straw, especially the application of maize straw plus pig manure was the most effective treatment for enhancing soil fauna community.

Intestinal Helminth Communities of Grey Partridge Perdix perdix and Common Pheasant Phasianus colchicus in Poland

The aim of this study was to describe the morphology and means of identification of helminths in native partridges (65) and introduced pheasants (32) in Poland and to determine the level of intestinal infection of these birds by helminths using parasitological and ecological indices. The birds were acquired during the hunting season in the years 2015–2017. Nematodes, Capillaria phasianina, cestodes, Railietina friedbergeri, and one trematode, Brachylaima sp. were recorded for the first time in partridges in Poland. Our findings indicate that parasites are more prevalent in pheasants (prevalence 70.4%) than in partridges (prevalence 50.0%). The component community and infracommunity of parasites of partridges are more diverse (Simpson’s diversity index: 0.63 and mean Brillouin diversity index: 0.10 ± 0.17) and less dominated by a single parasite species (Capillaria sp., Berger-Parker dominance index: 0.53) than the pheasant parasite community (Simpson’s diversity index: 0.07, mean Brillouin diversity index: 0.005 ± 0.02, dominant species Heterakis gallinarum, Berger-Parker dominance index: 0.96). There were statistically significant differences between partridges and pheasants in the Brillouin diversity index and in the prevalence of Heterakis gallinarum (55.6% in pheasants vs. 19.0 in partridges). There were significant differences between wild and farmed partridges in the prevalence of infection by Capillaria sp. (4.3% vs. 37.5%) and H. gallinarum (39.1 vs. 6.2%). In conclusion, the pheasant was shown to be a reservoir, carrier, and shedder of nematodes, which may increase the risk of infection in partridges.

Diversity of Butterflies (Hexapoda: Lepidoptera: Rhopalocera) Around Campus 4 of Universitas Ahmad Dahlan

The conversion of land functions can result in a decrease of environmental quality, which can reduce the diversity of butterflies. This study aimed to determine the diversity level and to find the most abundant and less abundant butterfly species around campus 4 UAD. The sampling was done at campus area, vacant land, rice fields and housing sites. Each of these sites had 2 plots and consisted of 5 subplots, respectively. Sampling was carried out four times, which was done in the morning at 08.00 - 11.00 and in the afternoon at 15.00 - 17.00. Butterflies caught using a sweep net. The data were analyzed by inferential analysis, namely Pearson correlation test. The calculation of the diversity level of butterflies was carried out by calculating the importance value index, the diversity Shannon-Wiener index, and the Simpson dominance index. The results showed that the diversity level of Shannon Wiener index of butterflies around the campus 4 UAD showed a low level (0.67). The species of butterflies found around campus 4 UAD were Acraea violae, Aphrissa statira, Appias libythea, Appias olferna, Catopsilia pyranthe, Catopsilia Scylla, Danaus Chrysippus, Elymnias hypermnestra, Junonia almana, and Junonia atlites. The most abundant butterfly was C. pyranthe with 125 individuals whereas the least abundant was A. libythea with 1 individual. This suggested that the ecosystem around campus 4 UAD is disturbed category; causing instability of the diversity that exists, including butterflies.