Assembling/Worlding Cities

This article explores the assembling and worlding of cities as both aspirational and evaluative processes in which cities are assembled, compared, and “positioned.” These practices involve the global circulation of expertise, best practices, models, and technologies related to how best to develop and govern cities. From specific examples from the authors' research, it is argued that the two distinct but overlapping notions of assembling and worlding help us conceptualize the contemporary urban–global condition. Building on the article's insights, we end this Urban Pulse with some questions for future global urban studies.     

Actor-networks and implementation: examples from conservation GIS in Ecuador

Recommendations for implementation and evaluation of Geographical Information Systems (GIS) can benfit from a broader theoretical foundation to support investigation, understanding and improvement. This paper discusses Actor-Network Theory (ANT) as a framework to delineate and evaluate the social and technical interactions involved in GIS implementation. The proposed process traces actor-network interactions through texts, technical objects, people, money and control. Actor alignment, actor-network stability and obligatory points of passage are evaluated to compare actor-networks. Case study research on conservation GIS implementation in Ecuador illustrates these methods. The strength of these actor-networks is examined through analysis of actors' interactions and the presence and function of an obligatory point of passage. Stronger actor-networks exhibit alignment among actors, co-location of an obligatory point of passage with the center of calculation and credit sharing.     

64层锥束CT扫描的优化系统

近年来X射线断层成像(CT)技术获得了突飞猛进的发展,自1998年推出4层螺旋CT后,CT扫描设备在容积覆盖,空间分辨率,扫描速度,切片数方面取得了长足进展.这不仅给医学应用带来了深远的影响,同时也给CT系统设计提出了巨大的挑战.容积CT(VCT)的设计过程引入了各种策略来战胜其复杂性.这些方法学包括:理论分析,系统性能预测的图像分析工具,各种基于专家背对背评价的参数优化.本文论述了64层CT系统设计中的一些考虑因素及优化过程.这些设计过程保证了锥束CT的优化性能.首批客户的应用反馈显示了我们设计实践的有效率性.     

The morphological response of foredunes at a breached barrier system to winter 2013/2014 storms on the southwest coast of Ireland

The level of storminess in Ireland during the winter of 2013/2014 was exceptional, the effects of which cost the Irish state in excess of €260 million in infrastructure repair and insurance claims. In Ireland, a lack of coastal process data from monitoring programmes means that the response of protective barrier coasts to such events remains largely un‐investigated. This study addresses this issue through an examination of the geomorphic impacts of recent storms, including those that occurred during the winter 2013/2014, on a breached barrier on the southwest coast of Ireland. Data from a two‐year terrestrial laser scanning (TLS) monitoring campaign shows that the winter 2013/2014 events caused a major (>50 m) dune recession at Rossbehy, County Kerry. Results from a simple linear regression analysis indicate storm duration plays an important role in the removal of foredunes at the study site. Given the fact that the frequency of intense storms in the vicinity of Ireland is forecast to increase within the next century, a scientific understanding of barrier response to such events is critical to inform sound management practices. Copyright © 2016 John Wiley & Sons, Ltd.     

Comments on Buzan et al. “Positive Relationships between Freshwater Inflow and Oyster Abundance in Galveston Bay,Texas”

Buzan et al. critique Turner’s (Estuaries and Coasts 29:345–352, 2006) analysis of the relationship between freshwater inflow and oyster productivity in the Gulf of Mexico, using 16 years of fisheries-independent data for Galveston Bay. They conclude that the catch-per-unit effort (CPUE; number h⁻¹) of marketable oysters increase 1 to 2 years after years with increased freshwater inflows, and they express concerns that water supply managers may mis-apply the results of Turner (Estuaries and Coasts 29:345–352, 2006) to justify a reduced freshwater inflow to Galveston Bay. I find no relationship between the CPUE of oyster spat or marketable oyster density and the commercial harvest, but do find a strong inverse relationship between harvest and river discharge in Galveston Bay. There are three possible factors that may explain why the annual variations in the fisheries-independent data are not coherent with the annual variations in commercial harvest: variable levels of water quality, inconsistent fishing effort, and the fact that the fisheries-independent data are not prorated for the area of the reefs actually fished. I concur, completely, with the apprehension that reductions in freshwater inflow will be implemented without examining the full set of assumptions and consequences, and thereby compromise estuarine ecosystem quality, and perhaps permanently, before mistakes can be seen or reversed.     

A molecular dynamics study of natural organic matter: 1. Lignin, kerogen and soot

Molecular dynamics (MD) simulations were performed on molecular models of a spectrum of natural organic matter (NOM) samples represented by two lignin samples (a softwood lignin and a hardwood lignin), a kerogen (Green River Shale kerogen) and a soot sample (n-hexane soot). Simulated thermodynamic properties of each model, including glass transition temperature (T_g), thermal expansion coefficient (α), density (ρ) and solubility parameter (δ) were compared against experimental data for corresponding samples. Results revealed relatively good agreement for glass transition temperature and solubility parameter for softwood lignin, Green River Shale kerogen and n-hexane soot models. An unexpectedly low solubility parameter for a hardwood lignin model suggests, however, certain model deficiencies in terms of intermolecular interactions. In addition, a lower density for a n-hexane soot model relative to the sample was attributed to the small cluster size and poor parallel stacking of aromatic clusters in the model. Discussion of the results is provided in the context of utilizing thermodynamic properties as constraints for improved structural modeling of NOM.     

The US army in operations other than War: A time to revive military geography

This paper revisits and interrelates the scope of military geography and the changing role of the military, two themes previously addressed in the 1993 and 1994 special editions ofGeoJournal. I begin by tracing the evolution of military geography in the US from World War I through the end of the Gulf War to reveal the demise of the subfield within American academic geography. Within the context of the post-Cold War era, I describe the military's reorientation and emphasize the need and opportunity to broaden the scope of military geography accordingly. The military's current operating environment is best characterized by operations other than war, undertaken on an unprecedented scale. Military geographers and regional, systematic, and technical experts throughout the discipline now have an unparalleled opportunity to contribute to the success of peacekeeping, humanitarian, and disaster assistance missions with which the military is currently preoccupied. Initiatives by academic geographers would not only enhance mission accomplishment from the military and federal government's perspective, but might also help to revive military geography as a legitimate subfield by demonstrating that military geographic endeavors can be both socially responsible and politically correct, particularly within operations other than war.     

Magombedze: A new H-chondrite with light-dark structure

Abstract— Magombedze is a light-dark structured H-chondrite breccia that fell in Zimbabwe on 1990 July 2 at 15:30 GMT. White clasts are moderately shocked and have equilibrated mafic silicates (pyroxene Fs_16–18, olivine Fa_18–19) together with clear optically-recognizable plagioclase of variable composition (An_9–13 found); chondrules are distinct but contain no trace of preserved glass. The darker surrounding material contains a higher proportion of fine-grained metal and sulfide than the white clasts, and many of its constituent grains show little evidence of shock. Mafic silicates in the dark lithology are distinctly less-equilibrated (pyroxene Fs_5–21, olivine Fa_11–20) than those in the white clasts, and many chondrules preserve brown devitrified glass; some metamorphic plagioclase of variable composition (An_11–22, found) is present. Some monoclinic pyroxene occurs in both fractions, but it is relatively common in the dark fraction. The white clasts are classified as H5, and the enclosing dark material is H3–5.     

Morphological variation of Stephanodiscus niagarae Ehrenb. (Bacillariophyta) in a Lake Ontario sediment core

Stephanodiscus niagarae populations in a core from Lake Ontario show systematic variation in radial puncta number and mean valve diameter. Puncta number is stable in specimens from samples deposited between 1720 and 1844. Puncta number gradually increases in samples deposited between 1860 and 1947, then increases rapidly to high numbers in samples deposited after 1964. Mean valve diameter is relatively high in specimens from samples deposited between 1720 and 1959. Diameter of specimens deposited during this period fluctuates around a mean of 63.2 m. Mean diameter of specimens deposited from 1959 to 1980 is only 42.5 m. We conclude that the trend in puncta number reflects the time course of eutrophication in Lake Ontario. We interpret the precipitous decline in mean diameter as an indication that conditions in the lake after the late 1950's did not permit sexual reproduction in this species.     

Broadband submillimeter measurements of the full Moon center brightness temperature and application to a lunar eclipse

We report on observations of the full Moon brightness temperature covering the frequency range of 300-950 GHz, and also on observations of the lunar eclipse of July 16, 2000, though only covering the frequency range of 165-365 GHz due to poor atmospheric transmission at higher frequencies. All observations were performed from the summit of Mauna Kea (HI) using a Fourier Transform Spectrometer mounted on the Caltech Submillimeter Observatory and supplemented by measurements of the atmospheric opacity using a 183 GHz Water Vapor Monitor. The telescope was pointed to the center of the lunar disk (with a footprint of ∼45-15 km on the Moon at 300 through 900 GHz). In order to obtain the correct values of the Moon brightness temperatures at all frequencies we carefully corrected for the atmospheric absorption, which varies across the submillimeter domain. This correction is fully described. The measured pre-eclipse brightness temperature is around 337 K in the 165-365 GHz range. This temperature slightly increases with frequency to reach ∼353 K at 950 GHz, according to previous broader band data. The magnitude of the temperature drop observed during the eclipse at 265 GHz (central frequency of the band covered) was about ∼70 K, in very good agreement with previous millimeter-wave measurements of other lunar eclipses. We detected, in addition, a clear frequency trend in the temperature drop that has been compared to a thermal and microwave emission model of the lunar regolith, with the result of a good match of the relative flux drop at different frequencies between model and measurements.