Although there have been numerous studies of individual cities or groups of cities, there has never been a study of the urbanism of the Roman world as a whole, meaning that we have been poorly ...informed not only about the number of cities and how they were distributed and changed over time, but also about their sizes and populations, monumentality, and civic status. This book provides a new account of the urbanism of the Roman world between 100 BC and AD 300. To do so, it draws on a combination of textual sources and archaeological material to provide a new catalogue of cities, calculates new estimates of their areas and uses a range of population densities to estimate their populations, and brings together available information about their monumentality and civic status for the first time. This evidence demonstrates that, although there were relatively few cities, many had considerable sizes and populations, substantial amounts of monumentality, and held various kinds of civic status. This indicates that there was significant economic growth in this period, including both extensive and intensive economic growth, which resulted from an influx of wealth through conquest and the intrinsic changes that came with Roman rule (including the expansion of urbanism). This evidence also suggests that there was a system that was characterized by areas of intense urban demand, which was met through an efficient system for the extraction of necessity and luxury goods from immediate hinterlands and an effective system for bringing these items from further afield. The disruption of these links seems to have put this system under considerable strain towards the end of this period and may have been sufficient to cause its ultimate collapse. This appears to have been in marked contrast to the medieval and early modern periods, when urbanism was more able to respond to changes in supply and demand.
Despite the recent flurry of interest in various aspects of ancient urbanism, we still know little about how much traffic flowed in and out of ancient cities, in part because of problems with using ...commodities as proxies for trade. This article investigates another approach, which is to estimate these flows from the built environment, concentrating on transport infrastructure such as city gates. To do this, I begin by discussing a new model for how we would expect this kind of infrastructure to expand with population, before investigating the relationship between the populations of sites and the total numbers and widths of city gates, focusing on the Greek and Roman world. The results suggest that there is indeed a systematic relationship between the estimated populations of cities and transport infrastructure, which is entirely consistent with broader theoretical and empirical expectations. This gives us a new way of exploring the connectivity and integration of ancient cities, contributing to a growing body of general theory about how settlements operate across space and time.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Oxide nanoparticles can exhibit unique chemical products due to size limitations and a high density of corner or edge surface sites. Fernandez-Garcia, et al provide a review of recent studies that ...deal with the chemistry of nanostructured oxides.
The design of power magnetic components for operation at high frequency (HF, 3-30 MHz) has been hindered by a lack of magnetic material performance data and by the limited design theory in that ...frequency range. To address these deficiencies, we have measured and present core loss data for a variety of commercially available magnetic materials in the HF range. In addition, we extend the theory of performance factor for appropriate use in the HF design. Since magnetic materials suitable for HF applications tend to have low permeability, we also consider the impact of low permeability on design. We conclude that, with appropriate material selection and design, increased frequencies can continue to yield improved power density well into the HF regime.
Emergence and spread of antibiotic resistance has become a global health threat and is often linked with overuse and misuse of clinical and veterinary chemotherapeutic agents. Modern industrial-scale ...animal feeding operations rely extensively on veterinary pharmaceuticals, including antibiotics, to augment animal growth. Following excretion, antibiotics are transported through the environment via runoff, leaching, and land application of manure; however, airborne transport from feed yards has not been characterized.
The goal of this study was to determine the extent to which antibiotics, antibiotic resistance genes (ARG), and ruminant-associated microbes are aerially dispersed via particulate matter (PM) derived from large-scale beef cattle feed yards.
PM was collected downwind and upwind of 10 beef cattle feed yards. After extraction from PM, five veterinary antibiotics were quantified via high-performance liquid chromatography with tandem mass spectrometry, ARG were quantified via targeted quantitative polymerase chain reaction, and microbial community diversity was analyzed via 16S rRNA amplification and sequencing.
Airborne PM derived from feed yards facilitated dispersal of several veterinary antibiotics, as well as microbial communities containing ARG. Concentrations of several antibiotics in airborne PM immediately downwind of feed yards ranged from 0.5 to 4.6 μg/g of PM. Microbial communities of PM collected downwind of feed yards were enriched with ruminant-associated taxa and were distinct when compared to upwind PM assemblages. Furthermore, genes encoding resistance to tetracycline antibiotics were significantly more abundant in PM collected downwind of feed yards as compared to upwind.
Wind-dispersed PM from feed yards harbors antibiotics, bacteria, and ARGs.
Celotno besedilo
Dostopno za:
CEKLJ, DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
There has recently been a great deal of interest in the effects of the sizes of communities on the social and economic conditions of settlements, drawing on theoretical and empirical work on complex ...systems. However, although it is clear that there is a series of relationships between the sizes of sites and their various attributes in a range of modern and non-modern contexts, it is not yet known whether these relationships extend to life
within
settlements, between different neighbourhoods, blocks, or individual households. In this article, I investigate whether this is the case by focusing on one site, Pompeii. The results show that there is indeed a series of relationships between the sizes of structures, the numbers and different kinds of rooms within them, and the numbers and different kinds of artefacts associated with them, which increase at a similar rate to those from other contexts. This demonstrates, for the first time, that the same scaling phenomena that have been identified across both contemporary and non-modern urban systems can also be found within the built environment of a single, well-documented ancient settlement. This suggests that the same, or similar, social network effects exist at multiple social, spatial, and temporal scales, from individual houses to entire cities, opening up the possibility of building a series of much more ambitious theoretical and empirical models of urbanism in future, which trace the variation both within and across settlements back to the net socio-economic and infrastructural consequences of embedding social networks within built environments.
A novel inverse CeO2/CuO catalyst for preferential oxidation of CO in H2-rich stream (CO-PROX) has been developed on the basis of a hypothesis extracted from previous work of the group (JACS 2007, ...129, 12064). Possible separation of the two competing oxidation reactions involved in the process (of CO and H2, respectively) is the key to modulation of overall CO-PROX activity and is based on involvement of different sites as most active ones for each of the two reactions. Achievement of large size CuO particles and adequate CeO2−CuO interfacial configurations in the inverse catalyst apparently allows appreciable enhancement of the catalytic properties of this kind of system for CO-PROX, constituting an interesting alternative to classic direct configurations so far explored for this process. Reasons for such behavior are analyzed on the basis of operando-XRD, -XAFS, and -DRIFTS studies.
Cell differentiation in yeast species is controlled by a reversible, programmed DNA-rearrangement process called mating-type switching. Switching is achieved by two functionally similar but ...structurally distinct processes in the budding yeast
and the fission yeast
In both species, haploid cells possess one active and two silent copies of the mating-type locus (a three-cassette structure), the active locus is cleaved, and synthesis-dependent strand annealing is used to replace it with a copy of a silent locus encoding the opposite mating-type information. Each species has its own set of components responsible for regulating these processes. In this review, we summarize knowledge about the function and evolution of mating-type switching components in these species, including mechanisms of heterochromatin formation,
locus cleavage, donor bias, lineage tracking, and environmental regulation of switching. We compare switching in these well-studied species to others such as
and the methylotrophic yeasts
and
We focus on some key questions: Which cells switch mating type? What molecular apparatus is required for switching? Where did it come from? And what is the evolutionary purpose of switching?
Peatlands contain one-third of the world's soil carbon (C). If destabilized, decomposition of this vast C bank could accelerate climate warming; however, the likelihood of this outcome remains ...unknown. Here, we examine peatland C stability through five years of whole-ecosystem warming and two years of elevated atmospheric carbon dioxide concentrations (eCO
). Warming exponentially increased methane (CH
) emissions and enhanced CH
production rates throughout the entire soil profile; although surface CH
production rates remain much greater than those at depth. Additionally, older deeper C sources played a larger role in decomposition following prolonged warming. Most troubling, decreases in CO
:CH
ratios in gas production, porewater concentrations, and emissions, indicate that the peatland is becoming more methanogenic with warming. We observed limited evidence of eCO
effects. Our results suggest that ecosystem responses are largely driven by surface peat, but that the vast C bank at depth in peatlands is responsive to prolonged warming.
Density pumpout and edge-localized mode (ELM) suppression by applied n=2 magnetic fields in low-collisionality DIII-D plasmas are shown to be correlated with the magnitude of the plasma response ...driven on the high-field side (HFS) of the magnetic axis but not the low-field side (LFS) midplane. These distinct responses are a direct measurement of a multimodal magnetic plasma response, with each structure preferentially excited by a different n=2 applied spectrum and preferentially detected on the LFS or HFS. Ideal and resistive magneto-hydrodynamic (MHD) calculations find that the LFS measurement is primarily sensitive to the excitation of stable kink modes, while the HFS measurement is primarily sensitive to resonant currents (whether fully shielding or partially penetrated). The resonant currents are themselves strongly modified by kink excitation, with the optimal applied field pitch for pumpout and ELM suppression significantly differing from equilibrium field alignment.
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