A microcosm study of the common night crawler earthworm (<Emphasis Type="Italic">Lumbricus terrestris</Emphasis>) and physical,chemical and biological properties of a designed urban soil

Designed soils are used in specialized urban areas, such as under sidewalks or on roof-tops. These substrates have coarse light-weight aggregates to meet load-bearing specifications with soil in voids for rooting medium. A full-factorial microcosm approach was used to study Lumbricus terrrestris (two adult worms added and no-worms added), compaction (bulk density of 1.95 and 1.48 g cm⁻³), and litter (litter and no-litter additions) in a designed soil. Earthworm biomass, soil physical, chemical, and biological properties, anion leaching and surface C efflux was measured on days 0, 7, 14, 21, 28, 72, 112, and 140. Earthworms decreased bulk density in compacted soil, but did not impact density of un-compacted soil. Earthworm biomass increased days 7 to 14, but declined from days 28 to 140, likely as result of the abrasiveness of the aggregate component and relatively shallow depth of the soil (25 cm). During the period of increasing earthworm biomass, surface C efflux, microbial biomass N, soil Ca²⁺ and NH₄⁺ increased with earthworms. During the period of declining earthworm biomass, surface C efflux, microbial biomass N, soil Ca²⁺ and NO₃⁻, and leachate NO₃⁻ increased, and soil pH decreased with earthworms. While alive and dying, Lumbricus terrestris stimulated microbial activity and biomass and nutrient availability, but an apparent shift to nitrification was observed as earthworm biomass declined. The results show Lumbricus terrestris to improve designed soil properties for plants, but the improvements may be short-lived due to the inability of these earthworms to survive in the designed soil.     

Unequivocal majority and Maskin-monotonicity

The unequivocal majority of a social choice rule is a number of agents such that whenever at least this many agents agree on the top alternative, then this alternative (and only this) is chosen. The smaller the unequivocal majority is, the closer it is to the standard (and accepted) majority concept. The question is how small can the unequivocal majority be and still permit the Nash-implementability of the social choice rule; i.e., its Maskin-monotonicity. We show that the smallest unequivocal majority compatible with Maskin-monotonicity is n- ë \fracn-1m û{n-\left\lfloor \frac{n-1}{m} \right\rfloor} , where n ≥ 3 is the number of agents and m ≥ 3 is the number of alternatives. This value is equal to the minimal number required for a majority to ensure the non-existence of cycles in pairwise comparisons. Our result has a twofold implication: (1) there is no Condorcet consistent social choice rule satisfying Maskin-monotonicity and (2) a social choice rule satisfies k-Condorcet consistency and Maskin-monotonicity if and only if k 3 n- ë \fracn-1m û{k\geq n-\left\lfloor \frac{n-1}{m}\right\rfloor}.     

Gray squirrel density,habitat suitability,and behavior in urban parks

Increased density, increased intraspecific aggression, and a reduced fear of humans have been suggested as the more observable and frequently described characteristics of wildlife species undergoing synurbization, the process of becoming urbanized. The relationship among these variables and how they may be related to environmental variables that change with urbanization is poorly understood. In this paper we explore the relationship between density, intraspecific aggression, and reduced fear of humans in urban populations of gray squirrel. In the summer and fall of 2003 and 2004, we studied a park with a documented high density of gray squirrels, Lafayette Park, Washington, DC, and six urban parks in Baltimore, MD with unknown squirrel densities. We used linear regression (SAS Institute, SAS/STAT user’s guide. SAS Institute, Cary, NC, 2005) to determine if there was a relationship (P < 0.05) between squirrel density and intraspecific aggression, squirrel density and reduced fear of humans (wariness), and squirrel density and habitat suitability. We found a positive association between density and intraspecific aggression (R ² = 0.81, P < 0.00). A negative relationship between density and wariness (, P < 0.00). However, no relationship was evident between habitat suitability and squirrel density (, P = 0.437).     

The NIP graph of a social welfare function

We consider the fraction of pairs of m distinct alternatives on which a social welfare function f may be nondictatorially independent and Pareto when the domain of f satisfies the free k-tuple property. When k = 4 we improve the existing upper bound to . When there are at least 26 alternatives and we obtain an original upper bound, . To obtain these results we define and analyze the graph formed from the nondictatorial independent and Pareto pairs and combine the results of this analysis with known results from extremal graph theory. The authors extend special thanks to the two reviewers and the editor for their comments.     

Serum oxidizability potential is associated with age and exercise test results

The purpose of this paper is to find out whether serum oxidizability potential measured before an exercise test (EXT) correlates with age and ischemic heart disease severity. Oxidizability potential was determined in 3 age groups, in gr. I patients < 45 years, in gr. II age range = 45 - 70years {\hbox{range}} = {45} - {7}0{\hbox{years}} , and in gr. III patients > 70 years. Included subjects had chronic ischemic heart disease (IHD) and underwent a symptom-limited EXT upon initiation of a cardiac rehabilitation program. The thermo-chemiluminescence (TCL) assay was used to assess serum oxidizability potential. This assay is based on heat-induced oxidation of serum, leading to the formation of electronically excited species in the form of unstable carbonyls, which further decompose into stable carbonyls and light energy (low chemiluminescence). Measured photons emission is represented by a kinetic curve which is described by its amplitude and slope (=ratio). We assessed the correlations of TCL ratio with age, exercise duration, metabolic equivalents (METS), maximal heart rate (mHR), maximal systolic BP, >1 mm S-T depression, diabetes, hypertension, smoking, left ventricular ejection fraction (LVEF)> or <40%, previous myocardial infarction, and aorto-coronary bypass surgery. A high TCL ratio (%) correlated well with METS (r = 0.82), mHR (r = 0.77) and with exercise-induced S-T segment shift (r = 0.86, p < 0.05). A lower serum oxidizability potential, expressed as a low TCL ratio, thus suggestive of a previous high oxidative stress, was found in the two older age groups compared to gr. I (<45 years), p = 0.041, and in particular, in gr. III patients with low LVEF%. The TCL ratio (%) in gr. III was 188.7 ± 14.5, 192 ± 17 in gr. II, and 214 ± 13 in gr. I (p < 0.05), and was 166 ± 13.1 in gr. III with LVEF < 45% as compared to 271 ± 15.7 in gr. I patients with LVEF > 45% (p < 0.01). A trend for lower TCL ratio (%) was found in diabetic, hypertensive, and post-coronary bypass surgery patients. A paradoxically low TCL ratio (low oxidizability potential) was observed in patients without S-T depression compared to patients with S-T depression (189 ± 22 vs. 201 ± 15, p = NS), due to the fact these patients had a much lower LVEF% and a lower exercise capacity. Serum oxidizability potential is associated with age, EXT parameters, results, and IHD severity. TCL ratio is an “easy-to-measure marker” that might be incorporated into risk assessment and prediction in aged IHD patients.     

The inverse Banzhaf problem

Let ${\mathcal{F}}Let F{\mathcal{F}} be a family of subsets of the ground set [n] = {1, 2, . . . , n}. For each i ? [n]{i \in [n]} we let p(F,i){p(\mathcal{F},i)} be the number of pairs of subsets that differ in the element i and exactly one of them is in F{\mathcal{F}}. We interpret p(F,i){p(\mathcal{F},i)} as the influence of that element. The normalized Banzhaf vector of F{\mathcal{F}}, denoted B(F){B(\mathcal{F})}, is the vector (B(F,1),...,B(F,n)){(B(\mathcal{F},1),\dots,B(\mathcal{F},n))}, where B(F,i)=\fracp(F,i)p(F){B(\mathcal{F},i)=\frac{p(\mathcal{F},i)}{p(\mathcal{F})}} and p(F){p(\mathcal{F})} is the sum of all p(F,i){p(\mathcal{F},i)}. The Banzhaf vector has been studied in the context of measuring voting power in voting games as well as in Boolean circuit theory. In this paper we investigate which non-negative vectors of sum 1 can be closely approximated by Banzhaf vectors of simple voting games. In particular, we show that if a vector has most of its weight concentrated in k < n coordinates, then it must be essentially the Banzhaf vector of some simple voting game with n − k dummy voters.     

Notes on Craven's conjecture

Craven's conjecture says that 2 ^n–1 is the maximum number of linear orders on {1, 2,...n} that simultaneously satisfy certain restrictions on three-element subsets of {1, 2,...n}. This is true for n=3, but the maximum exceeds 2 ^n–1 for n4. There is a set of nine linear orders on {1, 2, 3, 4} that satisfy the restrictions. As n gets large, the ratio of the size of the maximum satisfying set to 2 ^n–1 approaches infinity.     

Media Discussion on the Naturalization Policy for Syrians in Turkey

This study focuses on the public opinion on the naturalization policy for Syrians in Turkey. It analyses news media coverage in the religious, far‐right newspaper (Yeni Akit), a centre‐right newspaper (Hürriyet), a social democrat newspaper (Cumhuriyet), and a socialist‐left news portal (Solportal). The research question is: What are the metaphors, arguments, and omissions produced by media of different ideologies about the possible citizenship of Syrians in Turkey? The results show that metaphors and arguments differ according to ideological stance, suggesting that the current political polarization in Turkey affects the public's acceptance of Syrians and challenges Turkey's established migration policy. Each ideological stance accepts Syrians on a selective basis, implying that universal naturalization of Syrians is not welcome; instead, there seems to be consensus favouring naturalization according to socio‐economic criteria. These results indicate a need for a change in migration policy, especially concerning disadvantaged Syrians.     

Contrasting soil nitrogen dynamics across a montane meadow and urban lawn in a semi-arid watershed

Urbanization substantially increases nitrogen (N) inputs and hydrologic losses relative to wildland ecosystems, although the fate of N additions to lawns and remnant grasslands remains contested. In montane semi-arid ecosystems, N cycling is often closely coupled to snowmelt (the dominant period of infiltration) and snow cover, which impact soil temperature and moisture. Here, we compared soil N dynamics between a fertilized and irrigated urban lawn and nearby riparian meadow in Salt Lake City, Utah during a snow manipulation experiment. Snow removal increased freeze/thaw events but did not affect N pools, microbial biomass, denitrification potential, or soil oxygen (O₂). Mineral N was similar between sites despite lawn fertilization, but dissolved organic N (DON) was four-fold greater (2.1 ± 0.1 mg N l^?1) in lawn soil water. Infiltration was lower in the lawn subsoil, and leaching losses (modeled with Hydrus) were small at both sites (< 2 kg N ha^?1 y^?1) despite substantial lawn fertilization. Lawn soil O₂ fluctuated between 20.9 and 1.6 % following snowmelt and irrigation, but remained near 20 % in the meadow; the lawn had more reducing microsites as indicated by iron speciation. Post-snowmelt potential denitrification was six-fold greater in the lawn than the meadow. Lawns can potentially provide hotspots of denitrification in a semi-arid landscape that exceed some natural riparian ecosystems, whereas DON may represent an increasingly important form of N loss from lawns.     

Acyclic sets of linear orders

 A set of linear orders on {1,2, ℕ, n} is acyclic if no three of its orders have an embedded permutation 3-cycle {abc, cab, bca}. Let f (n) be the maximum cardinality of an acyclic set of linear orders on {1,2, ℕ, n}. The problem of determining f (n) has interested social choice theorists for many years because it is the greatest number of linear orders on a set of n alternatives that guarantees transitivity of majority preferences when every voter in an arbitrary finite set has any one of those orders as his or her preference order. This paper gives improved lower and upper bounds for f (n). We note that f (5)=20 and that all maximum acyclic sets at n=4, 5 are generated by an “alternating scheme.” This procedure becomes suboptimal at least by n=16, where a “replacement scheme” overtakes it. The presently-best large-n lower bound is approximately f (n)≥(2.1708) ⁿ . Received: 5 April 1995/Accepted: 10 November 1995     

Impact of soil compaction on soil biodiversity – does it matter in urban context?

Soil invertebrates are poorly studied in an urban context. Here we examine soil compaction in an urban environment, focusing on its persistence and its impact on biodiversity. This is achieved by studying a sensitive taxon, the collembolan (springtails). Soil core samples were taken in different location of a residential neighbourhood under construction, and collembolan species were extracted using a Berlese-Tullgren funnel. Soil compaction was determined by measuring bulk density. We documented soil compaction, ranging from 1 g/cm3 to 1.6 g/cm3. While collembolans are normally affected by compaction, such an effect was not observed in terms of species diversity, which remains relatively constant under all compaction levels. However, compaction was correlated with differences in the structure of collembolan communities. Indeed, we were able to discriminate different levels of compaction using collembolan community data alone. Moreover, this study confirms that compaction decreases with time. However, differences in species community structure can be observed one year after the end of the disturbance. Finally, we provide some insights into the reality of soil compaction in an urban environment, and highlight that the classical biodiversity indices may be insufficient for assessing the impact of an environmental disturbance, and that more detailed analyses at the community level may be very useful, or even indispensable.     

Existence of a multicameral core

When a single group uses majority rule to select a set of policies from an n-dimensional compact and convex set, a core generally exists if and only if n = 1. Finding analogous conditions for core existence when an n-dimensional action requires agreement from m groups has been an open problem. This paper provides a solution to this problem by establishing sufficient conditions for core existence and characterizing the location and dimensionality of the core for settings in which voters have Euclidean preferences. The conditions establish that a core may exist in any number of dimensions whenever n ≤ m as long as there is sufficient preference homogeneity within groups and heterogeneity between groups. With m > 1 the core is however generically empty for . These results provide a generalization of the median voter theorem and of non-existence results for contexts of concern to students of multiparty negotiation, comparative politics and international relations.     

Subgroup independence conditions on preferences

The concept of n-scale independence is introduced for a preference relation defined on ${\mathbb{R}^{n}=\mathbb{R}^{n_{1}}\times \cdots \times \mathbb{R}^{n_{p}}}$ . In addition to zero-independence and upper semicontinuity at zero, n-scale independence allows us to characterizate linear oligarchies as well as to offer a (semi)continuous welfarist analogue of Wilson’s theorem. We also include a characterization of the class of continuous, n-separable and n-scale independent, p ≥ 3, social orderings in terms of what we call homogeneous oligarchies.     

Location and visa-category determinants of naturalization in Australia

Immigrants' naturalization is conditioned by demographic, socioeconomic and contextual factors, but little is known about how it is affected by permanent visa category and geographic location at the destination. Using the 2016 Australian Census and Migrants Integrated Dataset (ACMID) and Probit regression analysis, we examined how visa category and location of residence influence naturalization rates for Chinese and Indian migrants arriving in Australia between 2000 and 2016. Chinese migrants were most likely to naturalize if entering under a Humanitarian visa, and Indian migrants if under a Skilled Independent visa. Migrants in the Australian Capital Territory were the most likely to naturalize, and those in Victoria the least likely—a distinction sharpened by metropolitan as opposed to regional location. The transnational perspective, allied with cost–benefit and integration theories, performs well in accounting for these heterogeneities. The differences have clear policy and practice in Australia and for countries of origin.     

Soil-atmosphere exchange of carbon dioxide,methane and nitrous oxide in urban garden systems: impact of irrigation,fertiliser and mulch

Urban green spaces provide important ecosystem services, such as amenity, biodiversity, productivity, climate amelioration, hydrological and biogeochemical cycling. Intensively managed urban gardens can sequester carbon through vegetation growth and soil C increase, but may experience nitrous oxide (N₂O) emissions and reduced soil methane (CH₄) uptake from irrigation and fertiliser use. Soil atmosphere exchange of N₂O, CH₄ and carbon dioxide (CO₂) was measured in lawn and wood chip mulched garden areas in Melbourne, Australia in winter, spring and summer under various water and fertiliser regimes. Gas exchange before and after lawn fertiliser application was measured continuously for three weeks using an automated chamber system. Applying fertiliser led to a peak N₂O emission of >60 μg N m⁻² h⁻¹, but overall only weekly irrigation (10 mm) significantly increased mean soil N₂O emissions above that in other treatments. Under mulch, mean soil N₂O emissions (14.0 μg N m⁻² h⁻¹) were significantly smaller than from irrigated lawn (27.9 μg N m⁻² h⁻¹), whereas mean soil CH₄ uptake under mulch (−30.7 μg C m⁻² h⁻¹) was significantly greater (p < 0.01) than in any lawn treatment. Lawns were either a weak CH₄ sink or source. Soil C density (0–25 cm) under mulch (12.5 kg C m⁻²) was greater that under lawn (8.0 kg C m⁻²). On a carbon dioxide equivalent (CO₂-e) basis, soil N₂O emissions offset the benefits of soil CH₄ uptake. Mulched garden areas provide greatest C sequestration potential in soil and vegetation and the smallest non-CO₂ emissions, as soil CH₄ uptake offsets a large fraction of soil N₂O emissions. Results of this study suggest that reducing the irrigation and fertiliser application to lawns can help mitigate GHG emissions from urban garden systems, and increasing the area of mulched perennial garden beds can also provide net GHG benefits; however, this needs to be tested in other garden systems with different soil types and environmental conditions.     

Aggregation of smooth preferences

Suppose p is a smooth preference profile (for a society, N) belonging to a domain P ^N . Let σ be a voting rule, and σ(p)(x) be the set of alternatives in the space, W, which is preferred to x. The equilibrium E(σ(p)) is the set {x∈W:σ(p)(x) is empty}. A sufficient condition for existence of E(σ(p)) when p is convex is that a “dual”, or generalized gradient, dσ(p)(x), is non-empty at all x. Under certain conditions the dual “field”, dσ(p), admits a “social gradient field”Γ(p). Γ is called an “aggregator” on the domain P ^N if Γ is continuous for all p in P ^N . It is shown here that the “minmax” voting rule, σ, admits an aggregator when P ^N is the set of smooth, convex preference profiles (on a compact, convex topological vector space, W) and P ^N is endowed with a C ¹-topology. An aggregator can also be constructed on a domain of smooth, non-convex preferences when W is the compact interval. The construction of an aggregator for a general political economy is also discussed. Some remarks are addressed to the relationship between these results and the Chichilnisky-Heal theorem on the non-existence of a preference aggregator when P ^N is not contractible. Received: 4 July 1995 / Accepted: 26 August 1996     

Acyclic sets of linear orders: A progress report

Let f(n) be the maximum cardinality of an acyclic set of linear orders on {1, 2, … , n}. It is known that f(3)=4, f(4)=9, f(5)=20, and that all maximum-cardinality acyclic sets for n≤ 5 are constructed by an “alternating scheme”. We outline a proof that this scheme is optimal for n=6, where f (6)=45. It is known for large n that f (n) >(2.17)ⁿ and that no maximum-cardinality acyclic set conforms to the alternating scheme. Ran Raz recently proved that f (n)<c ⁿ for some c>0 and all n. We conjecture that f (n + m)≤f (n + 1) f (m + 1) for n , m≥ 1, which would imply f (n)<(2.591)^{n − 2} for all large n. Received: 12 April 2000/Accepted: 4 December 2000     

Heights of representative systems: A proof of Fishburn's conjecture

Representative systems with n-voters are hierarchical choice functions from {-1, 0, 1} ⁿ to {-1, 0, 1} constructed as iterations of weighted majority voting. The height of a representative system is the minimal number of iterations necessary for this construction.In the paper we give an upper bound for (n), the maximal height of any n-voter representative system, and show that goes to zero as n goes to infinity, thus proving a conjecture made by Fishburn. Technically, the results are obtained by transferring the problem to the context of proper simple games, which have a similar hierarchical structure, and using known results on heights of simple games.     

Soil microbial community of urban green infrastructures in a polar city

Urban and technogenic landscapes in subarctic zones are not considered comfortable habitats for soil microbiota. However, green infrastructures in polar cities can provide a new niche for the development of a microbial soil community. Soil microbial biomass and the diversity of cultivable microfungi have been studied in relation to the chemical and morphological properties of urban soils in the polar city of Apatity. The quantitative indicators based on fluorescence microscopy and PCR real-time methods as well as the qualitative composition of the cultivable microfungal community were used to characterize the microbial community. Changes in the morphological and chemical composition of urban soils included a shift in pH and increased C and N content compared with forest soil. Studies have shown that the biomass of microfungi and actinomycetes in urban soils was lower than in forest soils and equals 0.12–0.19 mg/g and 0.06–0.44?×?10^?3 mg/g, respectively. Bacterial biomass, on the contrary, increased in urban soils up to 2.6?×?10^–3 – 5.6?×?10^–3 mg/g. The number of ITS gene copies of fungi in urban soils varied from 5.0?×?10⁹ to 1.45?×?10¹⁰ copies/g of soil, reaching the highest values in the courtyard. The number of rRNA gene copies of bacteria and archaea in urban soils increased compared with forest soil and amounted to 2.37?×?10¹⁰ – 9.99?×?10¹⁰ and 0.4?×?10¹⁰ – 0.8?×?10¹⁰ copies/g of soil, respectively. In urban soils, morphological changes in microfungi, including the predominance of small spores, were revealed in comparison with forest soils, where mycelium prevailed. An increase in the diversity of microfungi in urban soil and changes in the structure of their communities compared with forest soil was noted. Microfungi found in urban soils are not typical of the background soils of the region and would be expected in more southern conditions. Among them, opportunistic fungi species have been identified in humans, which increases the risk of diseases in residents of the northern region.

     

Interactions between birds, fruit bats and exotic plants in urban Hong Kong, South China

I observed the use of exotic plant species by native birds and bats in 8 km² of urban Hong Kong. Twenty-nine plant taxa were used repeatedly. Five species accounted for most interactions with birds: Cinnamomum camphora (10 bird species), Ficus religiosa (6), Livistona chinensis (7) and Pyracantha crenulata (6) provided fruits, while Bombax ceiba (6) supplied nectar. Panicum maximum (2) and C. camphora (1) provided seeds for granivorous birds and Leucaena leucocephala is host to a psyllid consumed by small insectivores in winter. Most trophic interactions between exotics and fruit bats involved the fruits or flowers of Syzygium jambos, while Livistona chinensis provided roosting sites for Cynopterus sphinx. The fruiting phenologies of the exotic species differed from the local flora, with fruit of some species available for the majority of the year. Fruit characteristics for the most commonly eaten species are within the range for native fruit species, although most are larger and have a lower seed load than the medians for native species. Seed dispersal by birds and/or fruit bats is a necessary, but not sufficient, condition for the naturalization of fleshy-fruited plants in Hong Kong, but S. jambos is the only naturalizing exotic species that needs vertebrates for pollination.