Modelling submillimetre spectra of the protostellar infall candidates NGC1333-IRAS2 and Serpens SMM4

We present a radiative transfer model, which is applicable to the study of submillimetre spectral line observations of protostellar envelopes. The model uses an exact, non-LTE, spherically symmetric radiative transfer `Stenholm' method, which numerically solves the radiative transfer problem by the process of `Lambda-iteration'. We also present submillimetre spectral line data of the Class 0 protostars NGC1333-IRAS2 and Serpens SMM4. We examine the physical constraints which can be used to limit the number and range of parameters used in protostellar envelope models, and identify the turbulent velocity and tracer molecule abundance as the principle sources of uncertainty in the radiative transfer modelling. We explore the trends in the appearance of the predicted line profiles as key parameters in the models are varied. We find that the separation of the two peaks of a typical infall profile is dependent not on the evolutionary status of the collapsing protostar, but on the turbulent velocity dispersion in the envelope. We also find that the line shapes can be significantly altered by rotation. Fits are found for the observed line profiles of IRAS2 and SMM4 using plausible infall model parameters. The density and velocity profiles in our best fit models are inconsistent with a singular isothermal sphere model. We find better agreement with a form of collapse which assumes non-static initial conditions. We also find some evidence that the infall velocities are retarded from free-fall towards the centre of the cloud, probably by rotation, and that the envelope of SMM4 is rotationally flattened.Comment: Accepted by MNRA

Airborne particulate matter monitoring in Kenya using calibrated low cost sensors [discussion paper]

East African countries face an increasing threat from poor air quality, stemming from rapid urbanisation, population growth and a steep rise in fuel use and motorization rates. With few air quality monitoring systems available, this study provides the much needed high temporal resolution data to investigate the concentrations of particulate matter (PM) air pollution in Kenya. Calibrated low cost optical particle counters (OPCs) were deployed in Kenya in three locations: two in the capital of Nairobi and one in a rural location in the outskirts of Nanyuki, which is upwind of Nairobi. The two Nairobi sites consist of an urban background site and a roadside site. The instruments were composed of an Alphasense OPC-N2 optical particle counter (OPC) ran with a raspberry pi low cost microcomputer, packaged in a weather proof box. Measurements were conducted over a two-month period (February–March 2017) with an intensive study period when all measurements were active at all sites lasting two weeks. When collocated, the three OPC-N2 instruments demonstrated good inter-instrument precision with a coefficient of variance of 8.8±2.0% in the PM2.5 fraction. The low cost sensors had an absolute PM mass concentration calibration using a collocated gravimetric measurement at the urban background site in Nairobi. The mean daily PM1 mass concentration measured at the urban roadside, urban background and rural background sites were 23.9, 16.1, 8.8µgm−3. The mean daily PM2.5 mass concentration measured at the urban roadside, urban background and rural background sites were 36.6, 24.8, 13.0µgm−3. The mean daily PM10 mass concentration measured at the urban roadside, urban background and rural background sites were 93.7, 53.0, 19.5µgm−3. The urban measurements in Nairobi showed that particulate matter concentrations regularly exceed WHO guidelines in both the PM10 and PM2.5 size ranges. Following a Lenschow type approach we can estimate the urban and roadside increments that are applicable to Nairobi. Median urban and roadside increments are 33.1 and 43.3µgm−3 for PM10, respectively, the median urban and roadside increments are 7.1 and 18.3µgm−3 for PM2.5, respectively, and the median urban and roadside increments are 4.7 and 12.6µgm−3 for PM1, respectively. These increments highlight the importance of both the urban and roadside increments to urban air pollution in Nairobi. A clear diurnal behaviour in PM mass concentration was observed at both urban sites, which peaks during the morning and evening Nairobi rush hours; this was consistent with the high measured roadside increment indicating vehicular traffic being a dominant source of particulate matter in the city, accounting for approximately 48.1, 47.5, and 57.2% of the total particulate matter loading in the PM10, PM2.5 and PM1 size ranges, respectively. Collocated meteorological measurements at the urban sites were collected, allowing for an understanding of the location of major sources of particulate matter at the two sites. The potential problems of using low cost sensors for PM measurement without gravimetric calibration available at all sites are discussed. This study shows that calibrated low cost sensors can be used successfully to measure air pollution in cities like Nairobi. It demonstrates that low cost sensors could be used to create an affordable and reliable network to monitor air quality in cities

Airborne particulate matter monitoring in Kenya using calibrated low-cost sensors [final revised article]

East African countries face an increasing threat from poor air quality stemming from rapid urbanization, population growth, and a steep rise in fuel use and motorization rates. With few air quality monitoring systems available, this study provides much needed high temporal resolution data to investigate the concentrations of particulate matter (PM) air pollution in Kenya. Calibrated low-cost optical particle counters (OPCs) were deployed in Kenya in three locations: two in the capital Nairobi and one in a rural location in the outskirts of Nanyuki, which is upwind of Nairobi. The two Nairobi sites consist of an urban background site and a roadside site. The instruments were composed of an AlphaSense OPC-N2 ran with a Raspberry Pi low-cost microcomputer, packaged in a weather-proof box. Measurements were conducted over a 2-month period (February–March 2017) with an intensive study period when all measurements were active at all sites lasting 2 weeks. When collocated, the three OPCN2 instruments demonstrated good inter-instrument precision with a coefficient of variance of 8.8 ± 2.0 % in the fine particle fraction (PM2.5). The low-cost sensors had an absolute PM mass concentration calibration using a collocated gravimetric measurement at the urban background site in Nairobi. The mean daily PM1 mass concentration measured at the urban roadside, urban background and rural background sites were 23.9, 16.1 and 8.8 µg m−3 , respectively. The mean daily PM2.5 mass concentration measured at the urban roadside, urban background and rural background sites were 36.6, 24.8 and 13.0 µg m−3, respectively. The mean daily PM10 mass concentration measured at the urban roadside, urban background and rural background sites were 93.7, 53.0 and 19.5 µg m−3, respectively. The urban measurements in Nairobi showed that PM concentrations regularly exceed WHO guidelines in both the PM10 and PM2.5 size ranges. Following a “Lenschow”-type approach we can estimate the urban and roadside increments that are applicable to Nairobi (Lenschow et al., 2001). The median urban increment is 33.1 µg m−3 and the median roadside increment is 43.3 µg m−3 for PM2.5. For PM1, the median urban increment is 4.7 µg m−3 and the median roadside increment is 12.6 µg m−3. These increments highlight the importance of both the urban and roadside increments to urban air pollution in Nairobi. A clear diurnal behaviour in PM mass concentration was observed at both urban sites, which peaks during the morning and evening Nairobi rush hours; this was consistent with the high roadside increment indicating that vehicular traffic is a dominant source of PM in the city, accounting for approximately 48.1 %, 47.5 % and 57.2 % of the total PM loading in the PM10, PM2.5 and PM1 size ranges, respectively. Collocated meteorological measurements at the urban sites were collected, allowing for an understanding of the location of major sources of particulate matter at the two sites. The potential problems of using low-cost sensors for PM measurement without gravimetric calibration available at all sites are discussed. This study shows that calibrated low-cost sensors can be successfully used to measure air pollution in cities like Nairobi. It demonstrates that low-cost sensors could be used to create an affordable and reliable network to monitor air quality in cities

The Regeneration Games: Commodities, Gifts and the Economics of London 2012

This paper considers contradictions between two concurrent and tacit conceptions of the Olympic ‘legacy’, setting out one conception that understands the games and their legacies as gifts alongside and as counterpoint to the prevailing discourse, which conceives Olympic assets as commodities. The paper critically examines press and governmental discussion of legacy, in order to locate these in the context of a wider perspective contrasting ‘gift’ and ‘commodity’ Olympics – setting anthropological conceptions of gift-based sociality as a necessary supplement to contractual and dis-embedded socioeconomic organizational assumptions underpinning the commodity Olympics. Costbenefit planning is central to modern city building and mega-event delivery. The paper considers the insufficiency of this approach as the exclusive paradigm within which to frame and manage a dynamic socio-economic and cultural legacy arising from the 2012 games

Native fish in Northland: application of the River Values Assessment System (RiVAS and RiVAS+)

The fourth application of the River Values Assessment System (RiVAS and RiVAS+) for native fisheries value was made in the Northland region. Data for nine out of ten indicators were provided from modelling undertaken by Cawthron Institute using a variety of databases including the NZFFD and FENZ. The expert panel then checked the modelling results and adjusted where appropriate based on local knowledge, and it populated the Population Stronghold indicator. Of 27 river catchment/clusters evaluated, nine were considered of national significance, namely the Bay of Islands North, Bay of Islands South, East Coast, Herekino, Hokianga, Mangamuka, Waihou, Waipoua and Wairoa. The Wairoa scored very poorly for all attributes other than presence of many at risk species. The remaining 18 are of regional significance. No river catchment/clusters were identified as being of local significance. The RIVAS+ identified work that can be done to reduce the inference on migratory fish movements caused by a barrier on the Waipoua River.This work was funded by Northland Regional Council and we gratefully acknowledge their support

The Endogenous Th17 Response in NO<inf>2</inf>-Promoted Allergic Airway Disease Is Dispensable for Airway Hyperresponsiveness and Distinct from Th17 Adoptive Transfer

Severe, glucocorticoid-resistant asthma comprises 5-7% of patients with asthma. IL-17 is a biomarker of severe asthma, and the adoptive transfer of Th17 cells in mice is sufficient to induce glucocorticoid-resistant allergic airway disease. Nitrogen dioxide (NO2) is an environmental toxin that correlates with asthma severity, exacerbation, and risk of adverse outcomes. Mice that are allergically sensitized to the antigen ovalbumin by exposure to NO2 exhibit a mixed Th2/Th17 adaptive immune response and eosinophil and neutrophil recruitment to the airway following antigen challenge, a phenotype reminiscent of severe clinical asthma. Because IL-1 receptor (IL-1R) signaling is critical in the generation of the Th17 response in vivo, we hypothesized that the IL-1R/Th17 axis contributes to pulmonary inflammation and airway hyperresponsiveness (AHR) in NO2-promoted allergic airway disease and manifests in glucocorticoid-resistant cytokine production. IL-17A neutralization at the time of antigen challenge or genetic deficiency in IL-1R resulted in decreased neutrophil recruitment to the airway following antigen challenge but did not protect against the development of AHR. Instead, IL-1R-/- mice developed exacerbated AHR compared to WT mice. Lung cells from NO2-allergically inflamed mice that were treated in vitro with dexamethasone (Dex) during antigen restimulation exhibited reduced Th17 cytokine production, whereas Th17 cytokine production by lung cells from recipient mice of in vitro Th17-polarized OTII T-cells was resistant to Dex. These results demonstrate that the IL-1R/Th17 axis does not contribute to AHR development in NO2-promoted allergic airway disease, that Th17 adoptive transfer does not necessarily reflect an endogenously-generated Th17 response, and that functions of Th17 responses are contingent on the experimental conditions in which they are generated. © 2013 Martin et al

Dynamic Analysis of Vascular Morphogenesis Using Transgenic Quail Embryos

Background: One of the least understood and most central questions confronting biologists is how initially simple clusters or sheet-like cell collectives can assemble into highly complex three-dimensional functional tissues and organs. Due to the limits of oxygen diffusion, blood vessels are an essential and ubiquitous presence in all amniote tissues and organs. Vasculogenesis, the de novo self-assembly of endothelial cell (EC) precursors into endothelial tubes, is the first step in blood vessel formation [1]. Static imaging and in vitro models are wholly inadequate to capture many aspects of vascular pattern formation in vivo, because vasculogenesis involves dynamic changes of the endothelial cells and of the forming blood vessels, in an embryo that is changing size and shape. Methodology/Principal Findings: We have generated Tie1 transgenic quail lines Tg(tie1:H2B-eYFP) that express H2B-eYFP in all of their endothelial cells which permit investigations into early embryonic vascular morphogenesis with unprecedented clarity and insight. By combining the power of molecular genetics with the elegance of dynamic imaging, we follow the precise patterning of endothelial cells in space and time. We show that during vasculogenesis within the vascular plexus, ECs move independently to form the rudiments of blood vessels, all while collectively moving with gastrulating tissues that flow toward the embryo midline. The aortae are a composite of somatic derived ECs forming its dorsal regions and the splanchnic derived ECs forming its ventral region. The ECs in the dorsal regions of the forming aortae exhibit variable mediolateral motions as they move rostrally; those in more ventral regions show significant lateral-to-medial movement as they course rostrally. Conclusions/Significance: The present results offer a powerful approach to the major challenge of studying the relative role(s) of the mechanical, molecular, and cellular mechanisms of vascular development. In past studies, the advantages of the molecular genetic tools available in mouse were counterbalanced by the limited experimental accessibility needed for imaging and perturbation studies. Avian embryos provide the needed accessibility, but few genetic resources. The creation of transgenic quail with labeled endothelia builds upon the important roles that avian embryos have played in previous studies of vascular development

Visual onset expands subjective time

We report a distortion of subjective time perception in which the duration of a first interval is perceived to be longer than the succeeding interval of the same duration. The amount of time expansion depends on the onset type defining the first interval. When a stimulus appears abruptly, its duration is perceived to be longer than when it appears following a stationary array. The difference in the processing time for the stimulus onset and motion onset, measured as reaction times, agrees with the difference in time expansion. Our results suggest that initial transient responses for a visual onset serve as a temporal marker for time estimation, and a systematic change in the processing time for onsets affects perceived time

Local festivals, social capital and sustainable destination development: experiences in East London

This paper explores the nature of social capital arising from engagement in local festivals and the implications of this for the social sustainability of an emerging destination. Two case studies are developed from a longitudinal research project which investigates local festivals staged in the Hackney Wick and Fish Island area adjacent to Queen Elizabeth Olympic Park in East London, UK between 2008 and 2014. This area has been directly affected by extensive development and regeneration efforts associated with the staging of the London 2012 Olympic Games. The two festivals considered here respond to the challenges and opportunities arising for local people as the area changes. One festival aims to foster a sense of community by creating shared experiences and improving communication across diverse groups. The other draws together the cultural community, links them to the opportunities arising as the area emerges as a destination, and attracts visitors. These festivals increase social capital in the area, but its distribution is very uneven. The accrual of social capital exacerbates existing inequalities within the host community, favouring the “haves” at the expense of the “have nots”. There are tensions between the development of social capital and social sustainability in this emerging destination