Toxic effect of the combined antibiotics ciprofloxacin, lincomycin, and tylosin on two species of marine diatoms

The role that antibiotics and other “emerging contaminants” play in shaping environmental microbial communities is of growing interest. The use of the prokaryotic metabolic inhibitors tylosin (T), lincomycin (L), and ciprofloxacin (C) in livestock and humans is both global and extensive. Each of these antibiotic compounds exhibits an affinity for sediment particles, increasing the likelihood of their deposition in the benthos of aquatic systems and each are often present in environmental samples. The purpose of this study was to determine if T, L, and C and their mixtures exhibit significant toxicity to two species of marine diatoms, an algal class comprised of ubiquitous eukaryotic primary producers. Subpopulations from laboratory cultures of Cylindrotheca closterium and Navicula ramosissima were reared in 24-well microtiter plates in the presence of single or combined antibiotics in dilution series. Population growth rates were assessed via epifluorescent microscopic cell counts, from which the half-max inhibitory concentrations (IC₅₀) were calculated and used as part of a toxic unit (TU) method for assessing mixture interactions. The single-compound IC₅₀'s were, for C. closterium: T = 0.27 mg L⁻¹, L = 14.16 mg L⁻¹, C = 55.43 mg L⁻¹, and for N. ramosissima: T = 0.99 mg L⁻¹, L = 11.08 mg L⁻¹, C = 72.12 mg L⁻¹. These values were generally higher than similar metrics for freshwater species. Mixture IC₅₀'s were generally synergistic against C. closterium and additive for N. ramosissima. Both single and combined treatments reduced or eliminated diatom motility. Monochemical responses were similar between species and were not useful for predicting mixture interactions. Mixtures had compound-specific and species-specific effects, favoring N. ramosissima. These results suggest that anthropogenic antibiotics may play a significant role in the ecology of environmental benthic microbial communities. They also suggest single-compound/species studies do not yield useful predictions of the ecological impact of anthropogenic pharmaceuticals.     

Welfare and population growth: The effect of the spatial dimension

This paper examines regional population growth and welfare levels in relation to the following variables: population size of the region; spatial location; and access. A theoretical model is developed relating welfare to income and range of choice, and empirically testable implications are derived. Regression equations estimated on 1960–1970 census data are used to test the implied hypotheses. It is shown that growth in both population and income (and the level of the latter) in a regional economy are directly and significantly related to the size of the regional population center and inversely related to the distance from that center. Quality of access is also found to be an important determinant of growth and welfare levels. The results suggest that national and/or local population distribution analysis or policy must take explicit account of spatial location and access quality.     

Sensitivity of marine microalgae to copper: the effect of biotic factors on copper adsorption and toxicity

Microalgae are sensitive indicators of environmental change and, as the basis of most freshwater and marine ecosystems, are widely used in the assessment of risk and development of environmental regulations for metals. However, interspecies differences in sensitivity to metals are not well understood. The relationship between metal-algal cell binding and copper sensitivity of marine microalgae was investigated using a series of 72-h growth-rate inhibition bioassays and short-term (1-h) uptake studies. A range of marine algae from different taxonomic groups were screened to determine whether copper adsorption to the cell membrane was influenced by biotic factors, such as the ultrastructure of cell walls and cell size. Minutocellus polymorphus was the most sensitive species to copper and Dunaliella tertiolecta the least sensitive, with 72-h IC50 values (concentration to inhibit growth-rate by 50%) of 0.6 and 530 microg Cu/L, respectively. Copper solution-cell partition coefficients at equilibrium (K(d)) were calculated for six species of algae on a per cell and surface area basis. The largest and smallest cells had the lowest and highest K(d) values, respectively (on a surface area basis), with a general (non-linear) trend of decreasing K(d) with increasing cell surface area (p=0.026), however, no relationship was found between K(d) and copper sensitivity, nor cell size and copper sensitivity. Interspecies differences in copper sensitivity were not related to cell size, cell wall type, taxonomic group or K(d) values. The differences in sensitivity may be due to differences in uptake rates across the plasma membrane, in internal binding mechanisms and/or detoxification mechanisms between the different microalgal species.     

Unveiling the veil: cultic,status, and ethnic representations of early imperial freedwomen

ABSTRACT

To corroborate that the veil was the standard mode of dress that symbolized pudicitia (virtue or chastity) for Roman matrons during the Augustan period (27 BCE—CE 14), scholars have frequently turned to the ancient material record, especially funerary monuments depicting freedwomen. In this article I demonstrate that there are several difficulties with the evidence and methodological approaches applied to this corpus of evidence. I offer a new approach to show that questions that anthropologists and historians of religion are currently asking about veiling in the Muslim world can be used to formulate the basis for the wide-ranging representations of ancient Roman veiling practices. This coupled with a reevaluation of both the iconographic and epigraphic evidence on Italian funerary monuments of freedslaves reveals various cultic, social, and ethnic factors that may have influenced depictions of Roman freedwomen with or without the veil.     

The distribution of cadmium between the marine alga Chlorella stigmatophora and sea water medium: Effect on algal growth

Distribution of dissolved cadmium between Chlorella stigmatophora and sea water medium—and possible effects of cadmium on the alga's growth—were investigated at cadmium concentrations between 1–10 mg 1⁻¹. Results show considerable cadmium uptake by Chlorella stigmatophora along the growth curve. No effect of cadmium uptake on growth expressed by number of cells was recorded but a considerable decrease in chlorophyll content per cell was established. A mathematical expression was developed for the distribution of cadmium between Chlorella stigmatophora and sea water medium.     

Artificial recharge of groundwater through sprinkling infiltration: Impacts on forest soil and the nutrient status and growth of Scots pine

We studied the chemical changes in forest soil and the effects on Scots pine trees caused by continuous sprinkling infiltration over a period of two years, followed by a recovery period of two years. Infiltration increased the water input onto the forest soil by a factor of approximately 1000. After one year of infiltration, the pH of the organic layer had risen from about 4.0 to 6.7. The NH₄-N concentration in the organic layer increased, most probably due to the NH₄ ions in the infiltration water, as the net N mineralization rate did not increase. Sprinkling infiltration initiated nitrification in the mineral soil. Macronutrient concentrations generally increased in the organic layer and mineral soil. An exception, however, was the concentration of extractable phosphorus, which decreased strongly during the infiltration period and did not show a recovery within two years. The NO₃-N and K concentrations had reverted back to their initial level during the two-year recovery period, while the concentrations of Ca, Mg and NH₄-N were still elevated. Nutrient concentrations in the pine needles increased on the infiltrated plots. However, the needle P concentration increased, despite the decrease in plant-available P in the soil. Despite the increase in the nutrient status, there were some visible signs of chlorosis in the current-year needles after two years of infiltration. The radial growth of the pines more than doubled on the infiltrated plots, which suggests that the very large increase in the water input onto the forest floor had no adverse effect on the functioning of the trees. However, a monitoring period of four years is not sufficient for detecting potential long term detrimental effects on forest trees.     

Homeownership, family and the gift effect: the case of Cyprus

Among the welfare pillars, family has been important relative to state or market in housing provision in Cyprus. In this respect Cyprus is similar to other southern European/Mediterranean countries, which are generally considered to have welfare systems characterised by the importance of family. Influence of family, described here by the term ‘familiocracy’, is reflected in what seems to be an extremely high rate of housing gifts in Cyprus, where parents provide their children with a gift of a dwelling when they get married. That this is a form of de-commodification in housing, is reflected in the fact that income and homeownership are not significantly related. Income and receipt of house as gift are also not significantly related. Gift-receiving households do have different consumption patterns from non-gift-receiving households however, but this is also shown to be related to familiocracy.     

Urban growth,transportation and the spatial dimension of the labour market: A note

Recently, Duranton and Turner estimated the impact of interstate highways on the average growth of US cities between 1983 and 2003. By estimating a structural model, one of their striking points is that increasing a city's initial stock of highways by 10 per cent leads to a 1.5 per cent positive respond of the city's employment over the sample period. This note mainly argues that their investigation leaves out potential spillovers of labour input from neighbouring growth centres/cities in the steady‐state directly implied by the open city assumption. More specifically, this contribution readily extends Duranton and Turner's work by a general equilibrium effect induced by the urban system's labour market fluctuations which is a direct consequence of the open city assumption.     

Determination of hydrophobicity of NOM by RP-HPLC,and the effect of pH and ionic strength

A reverse phase high performance liquid chromatography method for the determination of the hydrophobicity of natural organic matter (NOM) was developed by modification of an existing method based on elution with acetic acid/acetonitrile. The modified method separates the NOM into two well-defined groups according to their retention on a C18 column. The recovery was 101±11% for samples containing between 4 and 40 mg/L dissolved organic carbon (DOC). The method was tested for effects of ionic strength up to 0.8 eq. /L. Testing the method on eleven well-described NOM samples at pH 4.7 and 7.0 revealed the strong pH dependency of the hydrophobicity. The effect of pH on the hydrophobicity could be predicted from the proton binding properties of the NOM. Application of the method to NOM samples fractionated by HPSEC demonstrated considerable variations in hydrophobicity among the fractions, particularly at low pH.     

浅谈我国塑料绝阻燃和耐火电缆的现状及发展方向

一、概述电缆是社会经济发展的重要产品 ,近十年需求量大幅上升 ,生产电缆的企业也不断增加。由于电缆的护套和绝缘层一般由塑料及橡胶材料制成 ,因此随着电缆使用量的增加 ,特别是电缆密集敷设的场所 ,极易引起火灾。电缆密集敷设主要集中在高层及超高层建筑、大型娱乐场馆等人员密集的地方和邮电通信系统、大型工矿企业及地下工程。在高层及超高层建筑中 ,电缆往往密集敷设在电缆通道内 ,一旦火灾发生 ,火将顺着电缆延燃而蔓延到其他部位和其他楼层 ,使火势扩大 ,从而造成重大经济损失 ,并且严重威胁人们生命安全。从消防部门统计的火灾数…     

The history of urban growth management in South Africa: tracking the origin and current status of urban edge policies in three metropolitan municipalities

ABSTRACT

For many cities in the Global South, colonialism played a dominant role in shaping their urban form. The historical objective of planning in colonial mother-cities was dealing with poor health and living conditions, therefore a planning approach similar to that followed in post-war Britain would appear beneficial in post-colonial cities, characterized by environmental and physical infrastructure unable to cope with massive population growth. Urban growth management is a discourse born in an attempt to control the growing industrial city in the early twentieth century, and in recent years applied through instruments such as urban edges or growth boundaries to limit urban sprawl and encourage higher density urban development. In South Africa, the principles of compaction and urban growth management formed part of the post-apartheid planning agenda towards transforming the inefficient and fragmented landscape inherited from separate spatial development. Consequently, urban edges and urban growth boundaries formed key components of municipal spatial planning frameworks since the early 2000s. The purpose of this paper is to explore the origin and status of urban edges in three metropolitan municipalities in South Africa to aid in understanding of these spatial instruments in the south.     

Heterotrophic and mixotrophic growth of Micractinium pusillum Fresenius in the presence of acetate and glucose: effect of light and acetate gradient concentration

The main objective of this study was to determine the importance of secondary mechanism of organic carbon utilization (mixotrophic and heterotrophic modes) in addition to CO2 fixation (photoautotrophic mode) in the green alga, Micractinium pusillum Fresenius (chlorophyta), isolated from a waste stabilization pond. The growth was studied in the presence of acetate and glucose. The incorporation rate of 14C- acetate was measured in the light and in the dark at different concentrations. Finally, in order to underline the role of photosynthesis and respiration processes in the acetate assimilation, the effect of two specific metabolic inhibitors, a specific inhibitor of photosystem II (DCMU) and an uncoupler respiratory (DNP), has been studied. The obtained results showed that M. pusillum grows in the presence of organic substrates, i.e., glucose and acetate, in the light (mixotrophic growth) as well as in the dark (Heterotrophic growth). The growth was much more important in the light than in the dark and more in the presence of glucose than of acetate. In the light, the presence of acetate led to a variation of growth parameters mumax, iotaopt, and beta. The effect of acetate gradient on the growth of the microalga was severe as soon as its concentration in the medium was higher. The acetate uptake followed a Michaelis-Menten kinetic in the light as well as in the dark. The capacity of assimilation was slightly higher in the dark. The utilization of DNP and DCMU indicates that acetate incorporation is an active process depending on both anabolic (photosynthesis) and catabolic (respiration) metabolisms, corroborating the model of the Michaelis-Menten kinetic.     

‘Generation rent’ and the emotions of private renting: self-worth,status and insecurity amongst low-income renters

Abstract

The UK private-rented sector is increasingly accommodating a diverse range of households, many of whom are young people struggling to access other forms of housing. For those at the bottom end of the sector, who typically have limited economic resources, it is a precarious housing tenure due to its expense and insecurity, yet few studies have explored qualitatively the emotional consequences of this for well-being. We address this gap in the ‘generation rent’ literature by focusing attention on those voices that have been less prominent in the literature. Informed by the theoretical lens of ‘residential alienation’, our study illustrates the emotional toll of private renting upon low-income groups in a national context where state regulation is more limited. In doing so, we add nuance to the literature surrounding socio-economic differentiation within the UK private-rented sector. Our arguments are also relevant to an international audience given global concerns about housing precarity and the politics of housing.     

Valley of the sun-drenched parking space: The growth,extent, and implications of parking infrastructure in Phoenix

There is little knowledge of how much parking infrastructure exists in cities despite clear evidence that abundant and underpriced parking has economic, environmental, and social consequences. Urban parking requirements are very precise and routinely enforced despite the fact that most cities have little to no knowledge about their own parking supply. To further explore these issues, a parking inventory for metropolitan Phoenix, Arizona, USA is developed by cross-referencing geospatial cadastral and roadway data with minimum parking requirements. Metropolitan Phoenix is chosen because it is relatively young, rapidly growing, highly sprawled, and car dependent. Historical growth of parking is also estimated by linking year of property development to required off-street and nearby on-street parking spaces. As of 2017, we estimate that there were 12.2 million parking spaces in the metropolitan region with 4.04 million inhabitants, 2.86 million registered personal vehicles, and 1.84 million jobs. Growth of parking in metro Phoenix has also been significant; since 1960, 10.9 million spaces have been added to the region compared to a population growth of 3.41 million, vehicle fleet growth of 2.63 million, and employment growth of 1.56 million jobs. Since the 2008 recession, parking growth in metro Phoenix has significantly slowed, but continued urban growth combined with substantial minimum parking requirements may promote more parking infrastructure than is needed. Planners and policy makers should value quantifying the growth and supply of parking in urban areas and consider reforming parking standards to promote sustainable urban growth.     

Intrinsic growth rate: a new approach to evaluate the effects of temperature, photoperiod and phosphorus-nitrogen concentrations on duckweed growth under controlled eutrophication

A comprehensive model based on a new approach was developed to simulate the duckweed growth under controlled conditions. Contrary to other approaches which use the specific growth rate, this approach uses the intrinsic growth rate which permits to differentiate the effect of duckweed mat density from that of temperature, photoperiod and phosphorus-nitrogen concentrations. The model was calibrated using data from laboratory experiments carried out during the present study and validated using other data from two literature sources. In both cases, the results demonstrated that the model was capable of predicting duckweed growth with a reliability of 95%.     

Place as layered and segmentary commodity: place branding,smart growth and the creation of product and value

Smart growth is a comprehensive version of spatial planning that can guide sustainable development and tackle negative social and environmental consequences of urbanization. In this paper we explore how an integration of spatial planning and place branding strategies can further the concept of smart growth and improve its chance at implementation. A review of the parallel evolutions of place branding and smart growth shows their shared interest in comprehensive visions, sensitivity for narratives of place and self, and the proposed embedding in participatory governance. The concept of layered and segmenatary commodification offers a novel perspective on value creation in smart growth and helps to develop new forms of smart growth, that combine and integrate elements of spatial planning and place branding.     

Trace metals in the marine bivalve Macoma balthica in the westerschelde estuary, The Nertherlands. Part 3: Variability of the role of cytosol in metal uptake by the clams

Tellinid clams Macoma balthica were sampled every 2 months for 2.5 years at two locations from the Westerschelde estuary (The Netherlands) and submitted to in vitro short-term exposure to Cd, Cu and Zn. Total and heat-stable cytosolic metal concentrations have been measured before and after exposure to study the effects of the sampling season on metal uptake by the bivalve. We observed much higher uptakes of Cd and, to a lesser extent, Cu in winter than in summer, while Zn appears to be constantly regulated. These phenomena are amplified in the cytosol, especially for Cd, a non-essential element, for which the concentrations after exposure can reach 35–45 μg·g⁻¹ (dry wt.) in winter, but only a maximum of 0.5 μg·g⁻¹ in summer, all natural values being between 0.01 and 0.1 μg·g⁻¹ on average. The contents (μg) of the various elements, either at the total or at the cytosolic level, are not constant, hence showing that the seasonal body weight fluctuation of the clams (dilution or concentration effect) is not the only parameter responsible for the metal uptake variability. Furthermore, we have shown that the proportion of cytosolic metal is not constant, but increases with the absolute cytosolic concentration up to 35–40. Therefore, the cytosolic phase of the cells plays a growing role in Cd, Cu and Zn storage as long as their total concentration increases.     

Cadmium(II) and zinc(II) adsorption by the aquatic moss Fontinalis antipyretica: effect of temperature, pH and water hardness

The biosorption of cadmium(II) and zinc(II) ions onto dried Fontinalis antipyretica, a widely spread aquatic moss, was studied under different values of temperature, initial pH and water hardness. The equilibrium was well described by Langmuir adsorption isotherms. Maximum biosorption capacity of cadmium was independent on temperature and averaged 28.0 mg g(-1) moss, whereas for zinc, capacity increased with temperature, from 11.5 mg g(-1) moss at 5 degrees C to 14.7 mg g(-1) moss at 30 degrees C. Optimum adsorption pH value was determined as 5.0 for both metal ions. Cadmium uptake was unaffected by the presence of calcium ions, but zinc sorption was improved when water hardness increased from 101.1 to 116.3 mg CaCO(3)l(-1). Inversely, as hardness increases, the competition with calcium ions strongly reduces the affinity of the biosorbent for zinc.     

Green growth machines,LEED ratings and value free development: the case of the Philadelphia property tax abatement

In this paper we examine an attempt in Philadelphia in 2009 to alter a popular and longstanding city property tax abatement program by connecting it to LEED building standards. We argue that the attempt to change the property tax abatement was an attempt by an insurgent growth coalition – what we call a ‘green growth machine' – to capture a greater proportion of the returns from land investment from the city's traditional growth machine. LEED was an important tool in the green growth machine's strategy, because the rating system has become a means by which growth machines have established green building as a component of the ideology of value free development. The attempt to alter the property tax abatement limited the extent to which LEED could be used as a tool in the construction of an ideology of value free development, which suggests both the limits to the power of that ideology, and how components of that ideology might be used to challenge a traditional growth machine.