44 results on '"Higgins, Christopher"'
Search Results
2. The pedagogies of morphology and gamification : linking gamification with spatial concepts
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Bruyns, Gerhard, Hasdell, Peter, Sepulveda, Diego, Qu, Lei, Endemann, Henry, Nel, Darren, Gera, Krity, Wei, Huaxin, Sun, Choi Hee, and Higgins, Christopher
- Subjects
NA - Abstract
Configurative and morphological studies harness indicators to support conceptual and spatial frameworks specific to formal models of cities. However, the presence of new indicators, the scale of territories, and morphological methods are not only revising the praxis of configurative approaches; they collectively impact how and in what way the knowledge transfer occurs within educational settings. This paper explains how the contextual setting of the Greater Bay Area (GBA) as an urban agglomeration (UA) shifts the morphological framework in both its analytic tools and in its design premise. The paper covers the crossover to gamification (gameboarding) as a 'design and test' methodology providing a step-by-step account of rapid and succinct gameboarding phases for morphological studies. With close to 17 speculative models and three years of a collaborative studio, conclusions are drawn on the value of hybridizing morphological education with gamification, challenging uniform planning practices for future development within complex ecosystems.
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- 2022
3. Mega morphologies of 21st century landscapes; the characteristics of an inverted-exterior city form
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Bruyns, Gerhard, Nel, Darren, Yixuan Peng, and Higgins, Christopher D
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- 2021
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4. Measuring mixed-use intensity in volumetric cities: density and interaction
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Higgins, Christopher D., Nel, Darren H., and Bruyns, Gerhard
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- 2021
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5. In pursuit of resilient urban form typologies: testing a quantitative approach for morphologically based urban resilience
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Nel, Darren, Bruyns, Gerhard, Higgins, Christopher D., and Yixuan Peng
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- 2021
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6. Additional file 6 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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Additional file 6. Pairwise t-test results for total sample, users with complete data sets only (sensitivity), and 1:1 matched users only (sensitivity).
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- 2020
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7. Additional file 3 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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ComputingMethodologies_PATTERNRECOGNITION ,ComputerSystemsOrganization_PROCESSORARCHITECTURES - Abstract
Additional file 3. Completed Mobile Application Rating Scale (MARS).
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- 2020
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8. Additional file 5 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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Additional file 5. ANCOVA results adjusting for pre-intervention mean daily step count for total sample, users with complete data sets only (sensitivity), and 1:1 matched users only (sensitivity).
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- 2020
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9. Additional file 9 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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Additional file 9. Completed STROBE Statement—checklist of items to be included in reports of observational studies.
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- 2020
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10. Additional file 7 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
- Abstract
Additional file 7. Mean steps per day in the pre-intervention and intervention periods by number of Step Together Challenges completed.
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- 2020
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11. Additional file 1 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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Data_FILES - Abstract
Additional file 1. Detailed description of the matching process.
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- 2020
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12. Additional file 2 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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Additional file 2. Study flowchart.
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- 2020
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13. Additional file 8 of Adding team-based financial incentives to the Carrot Rewards physical activity app increases daily step count on a population scale: a 24-week matched case control study
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Pearson, Emma, Prapavessis, Harry, Higgins, Christopher, Petrella, Robert, White, Lauren, and Mitchell, Marc
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Additional file 8. Completed TIDieR (Template for Intervention Description and Replication) Checklist.
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- 2020
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14. Reliability Analysis of Oregon Bridges Using WIM (Weigh-in-Motion) Data
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YANİK, Arcan and HIGGINS, Christopher
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Bridges,Reliability analysis,Weigh-in-Motion,Traffic ,Engineering ,Mühendislik ,Köprüler ,Güvenilirlik Analizi ,Hareket Halinde Tartma ,Trafik - Abstract
Bu çalışmada Oregon köprüleri için bir güvenilirlik analizi gerçekleştirilmiştir. Çalışma kapsamında kompozit olmayan çelik kirişli, betonarme T kesit kirişli ve öngerilmeli beton kirişli köprüler göz önüne alınmıştır. Güvenilirlik indisleri, çeşitli kiriş açıklıkları ve aralıkları için hesaplanmıştır. Yüklemelerde Amerikan otoyol ve taşıma standartlarını belirleyen kurum olan AASHTO’nun HS20 yükü ve 5 yıllık değerlendirme zamanı kullanılmıştır. Çalışma kapsamında gerçek ortalama günlük trafik (ADTT) değerleri kullanılmıştır. Hesaplamalarda Oregon eyaletine ait dört tane trafik bölgesine ait hareket halinde tartma (WIM) verileri kullanılmıştır. Bu trafik bölgeleri dört adet ADTT değerine karşı gelmektedir. Bu durumlar ADTT= 5,000, ADTT = 1,500 ve ADTT ≤ 500 değerlerine tekabül etmektedir. Bu çalışmanın mevcut çalışmalardan farkı kullanılan WIM verilerinin oldukça fazla sayıda olmasıdır. Bir yıl boyunca toplanan WIM verileri kullanılmıştır. Analizler sonucunda güvenilirlik indislerinin farklı kiriş aralıkları ve açıkları için moment ve kesme kuvveti etkisine göre 2.4 ten 6.4 e kadar değiştiği görülmüştür. Bulunan değerler literatürde yer alan değerler ile karşılaştırılmıştır., In this study a reliability analysis was carried out for Oregon bridges. Different bridge types that are non-composite steel girder, reinforced concrete T-beam, and prestressed concrete girder bridges were considered. Reliability indices were calculated for various span lengths and girder spacing. Reliability indices were estimated for AASHTO HS20 design loading considering a five-year evaluation period. The actual average daily truck traffic (ADTT) values were used during the calculation. Four WIM sites from Oregon state were taken into account in the analysis. These sites correspond to three different levels of ADTT which are approximately ADTT= 5,000, ADTT = 1,500 and ADTT ≤ 500 cases. The distinction of this paper from the existing literature is the large amount of WIM data used in the analysis. The resulting reliability indices ranged from 2.4 to 6.4 for different span lengths, girder spacing, load effects (moment or shear), type of girder and ADTT level. These indices were compared with the existing ones presented in the literature.
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- 2019
15. Suspect Screening of Hydrocarbon Surfactants in AFFFs and AFFF-Contaminated Groundwater by High-Resolution Mass Spectrometry
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García, Raymmah Aleyda, Chiaia-Hernández, Aurea, Lara-Martin, Pablo A., Loos, Martin, Hollender, Juliane, Oetjen, Karl, Higgins, Christopher P., and Field, Jennifer A.
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540 Chemistry ,910 Geography & travel - Abstract
Aqueous film-forming foams (AFFFs) are proprietary mixtures containing hydrocarbon surfactants and per- and polyfluoroalkyl substances (PFASs) that are used to extinguish hydrocarbonbased fuel fires. There is limited information on hydrocarbon surfactants in AFFFs and AFFF-contaminated groundwater even though hydrocarbon surfactants are more abundant (5−10% w/w) than PFASs (0.9−1.5% w/w) in AFFFs. Eight commercial AFFFs manufactured between 1988 and 2012 and 10 AFFF-contaminated groundwaters collected from near source zones of fire-fighter training areas were analyzed for suspect hydrocarbon surfactants by liquid chromatography quadrupole time-of-flight mass spectrometry. A suspect list and a homologous series detection computational tool, enviMass, were combined to screen for hydrocarbon surfactants. Nine classes of hydrocarbon surfactants were detected in AFFFs including octylphenol polyethoxylates, linear alcohol ethoxylates, ethoxylated cocoamines, alkyl ether sulfates, alkyl amido dipropionates, linear alkyl benzenesulfonates, alkyl sulfates, and polyethylene glycols. Of those, six were also found in groundwater along with diethanolamines and alkyl amido betaines, which were not found in the eight archived AFFFs. This indicates that although aerobically biodegradable, hydrocarbon surfactants likely persist in groundwater due to anaerobic aquifer conditions. To the best of our knowledge, this is the first screening for hydrocarbon surfactants in AFFFs and in AFFFcontaminated groundwater.
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- 2019
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16. AN ANALYTICAL STUDY ON STEEL GUSSET PLATES
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YANIK, Arcan, HIGGINS, Christopher, and SCOTT, Michael H.
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Köprüler,Çelik yapılar,Çelik guse plakları,İnşaat mühendisliği,Köprü birleşim elemanları ,Bridges,Bridge connections,Civil engineering,Steel structures,Steel gusset plates ,İnşaat Mühendisliği ,Civil Engineering - Abstract
1Ağustos 2007 tarihinde, Minnesota Amerika’da, Mississipi Nehri üzerindebulunan, Eyaletlerarası 35W (I-35W) adlı köprü çökmüştür. Bu trajik vaka, 13ölüm, 145 de yaralı ile sonuçlanmıştır. Bu üzücü kazaya çelik guse plakasındakitasarım kusuru nedeni ile oluşan zayıf birleşimin yol açtığı tespit edilmiştir.Bu trajik kaza, çelik guse plaklarının köprülerde tasarımının ve tatbikinin canalıcı öneme sahip olduğunu göstermiştir. Tasarım mühendislerinin çelik guse plaklarının dizaynına kayda değerehemniyet vermesi gerekmektedir. Bu çalışmada çelik guse plakların burkulmadavranışları incelenmiştir. Çelik guse plaklarının sonlu elemanlar yönteminegöre basınç yükü altındaki analizinde, (Higgins et al., 2016 ; Scottet al., 2008) tarafindan hazırlanmış bir program kullanılmıştır. Analizlerdetek eksenli gerilme şekil değiştirme plastisite modeli göz önüne alınmıştır.Çelik guse plaklarının üç boyutlu gerilme şekil değiştirme durumu tanımlanmışve doğrusal olmayan statik analizler gerçekleştirilmiştir. Analizler esnasında,çelik guse plaklarına, farklı düzlem dışı kusurların, farklı narinlikkatsayılarının ve farklı eleman boyutlarının etkisi incelenmiştir. Çelik guse plakalarındabulunan civataların plak içerisinde konumlarının değişiminin davranışa etkisi dearaştırılmıştır. Bu parametrelerdeki değişimin, maksimum göçme yükünün kritik Euler burkulmayükü oranına etkisi de incelenmiştir. Analizler sonucunda düzlem dışıkusurların çelik guse plaklarının basınç yükleri etkisi altındakideplasmanlarına önemli derecede etki ettiği görülmüştür., On August 1, 2007, the Interstate 35W (I-35W) bridge over theMississippi River in Minneapolis, Minnesota USA, collapsed, resulting in 13deaths and 145 injuries. The cause of the collapse was a design flaw resultedin week gusset plate connection. This very tragic example showed us again that,gusset plate design and implementation on bridges have crucial importance. Designers should give significantconsideration during the design of steel gusset plate connections. In this study, thebuckling behavior of steel gusset plates was investigated. An automatedfinite-element analysis program (Higgins et al.,2016 ; Scott et al., 2008), wasused to analyze the steel gusset plates behavior under compression load. Anuniaxial stress strain plasticity model was considered in the analysis. Thestress-strain relationship of the steel gusset plates was defined in threedimensions. Nonlinear static analysis of the gusset plates were performed. Differentout of plane imperfection, different slenderness ratios, different element sizeswere considered during the analysis. The effect ofchange in the fastener(bolt) location on the steel gusset plates were alsoexamined. Normalization of the ultimate failure loads of the given gusset platewith the critical Euler’s buckling load was defined. The variation of thisnormalization with respect to the change in the steel gusset plate parameters wasanalyzed. It was obtained that, imperfections have significant effect on thedisplacement capacity of the steel gusset plates under compression loads.
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- 2018
17. Zürich Statement on Future Actions on Per - and Polyfluoroalkyl Substances (PFASs)
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Ritscher, Amélie, Wang, Zhanyun, Scheringer, Martin, Boucher, Justin M., Ahrens, Lutz, Berger, Urs, Bintein, Sylvain, Bopp, Stephanie K., Borg, Daniel, Buser, Andreas M., Cousins, Ian, DeWitt, Jamie, Fletcher, Tony, Green, Christopher, Herzke, Dorte, Higgins, Christopher, Huang, Jun, Hung, Hayley, Knepper, Thomas, and Lau, Christopher S.
- Abstract
Per- and polyfluoroalkyl substances (PFASs) are man-made chemicals that contain at least one perfluoroalkyl moiety,–CnF2n–. To date,over 4,000 unique PFASs have been used in technical applications and consumer products, and some of them have been detected globally in humanand wildlife biomonitoring studies. Because of their extraordinary persistence, human and environmental exposure to PFASs will be a long-termsource of concern. Some PFASs such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) have been investigated extensivelyand thus regulated, but for many other PFASs, knowledge about their current uses and hazards is still very limited or missing entirely. To addressthis problem and prepare an action plan for the assessment and management of PFASs in the coming years, a group of more than 50 internationalscientists and regulators held a two-day workshop in November, 2017. The group identified both the respective needs of and common goals sharedby the scientific and the policy communities, made recommendations for cooperative actions, and outlined how the science–policy interfaceregarding PFASs can be strengthened using new approaches for assessing and managing highly persistent chemicals such as PFASs., Environmental Health Perspectives, 126 (8), ISSN:1552-9924, ISSN:0091-6765
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- 2018
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18. Organic carbon amendments for enhanced biological attenuation of trace organic contaminants in biochar-amended stormwater biofilters
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Ulrich, Bridget A., Vignola, Marta, Edgehouse, Katelynn, Werner, David, and Higgins, Christopher P.
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fungi ,QD ,complex mixtures - Abstract
This study sought to evaluate how dissolved organic carbon (DOC) affects attenuation of trace organic contaminants (TOrCs) in biochar-amended stormwater biofilters. It was hypothesized that (1) DOC-augmented runoff would demonstrate enhanced TOrC biodegradation and (2) biochar-amended sand bearing DOC-cultivated biofilms would achieve enhanced TOrC attenuation due to sorptive retention and biodegradation. Microcosm and column experiments were conducted utilizing actual runoff, DOC from straw and compost, and a suite of TOrCs. Biodegradation of TOrCs in runoff was more enhanced by compost DOC than straw DOC (particularly for atrazine, prometon, benzotriazole, and fipronil). 16S rRNA gene quantification and sequencing revealed that growth-induced microbial community changes were, among replicates, most consistent for compost-augmented microcosms and least consistent for raw runoff microcosms. Compost DOC most robustly enhanced utilization of TOrCs as carbon substrates, possibly due to higher residual nutrient levels upon TOrC exposure. Sand columns containing just 0.5 wt % biochar maintained sorptive TOrC retention in the presence of compost-DOC-cultivated biofilms, and TOrC removal was further enhanced by biological activity. Overall, these results suggest that coamendment with biochar and compost may robustly enhance TOrC attenuation in stormwater biofilters, a finding of significance for efforts to mitigate the impacts of runoff on water quality.
- Published
- 2017
19. Rapid Transit, Transit-Oriented Development, and the Contextual Sensitivity of Land Value Uplift in Toronto
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Higgins, Christopher D, Kanaroglou, Pavlos S, and School of Geography and Geology
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Transit-oriented Development ,Applied Econometrics ,Urban Planning ,Land-use Planning - Abstract
Rapid transit projects that increase accessibility should result in a localized land value uplift (LVU) benefit for locations near stations. A rich history of research has tested this hypothesis, generally operationalizing transit accessibility by proxy through distance from a transit station. However, a growing body of research has also demonstrated LVU effects from transit-oriented development (TOD) as individuals sort themselves into locations that best match their preferences and willingness to pay. Considering the interdependence of transportation and land use in the urban system, we argue that these benefits create a spatial bundle of TOD goods around transit stations and hypothesize that households are willing to pay a premium for locations in more transit-oriented station catchment areas. Utilizing latent class analysis, we quantify station area TOD submarkets. Next, interactions between these submarkets and station proximity in spatial hedonic regressions reveal that TOD is capitalized into land values in Toronto, though the maximum amount and spatial impact area of this capitalization differs by TOD context.
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- 2017
20. SERDP and ESTCP Workshop on Research and Demonstration Needs for Management of AFFF-Impacted Sites
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Stroo, Hans, Leeson, Andrea, Deeb, Rula A, Higgins, Christopher, Mills, Marc Allyn, Patton, Cara, Porter, Ron, Sedlak, David, Sepulveda, Marisol, Thompson, Tim, Schaefer, Charles, Willey, Janice, and Xavier, Macrina
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- 2017
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21. Performance of and amendments to urban bioretention systems for removal of stormwater contaminants
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Eisenbraun, Emma, Halpin, Brittnee, Portmann, Andrea, McDonough, Carrie, and Higgins, Christopher P.
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As urbanization has expanded, polluted urban stormwater runoff has become a greater concern. While originally installed to control water quantity by smoothing out urban runoff hydrographs, best management practices such as bioretention systems may also remove contaminants in runoff. This project had three primary goals: 1) to evaluate the performance of the Iris Rain Garden with respect to the removal of dissolved trace organic contaminants, 2) to determine the hydraulic conductivity of various geomedia, and 3) to determine the removal of targeted metal contaminants by various geomedia. It was found that the Iris Rain Garden reduced the amount of atrazine, caffeine, carbendazim, and triphenyl phosphate in stormwater runoff. Furthermore, hydraulic conductivity values for various types of geomedia were determined. Currently, work is being done with various geomedia to characterize the removal of heavy metals.
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- 2017
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22. Biodegradation of trace organic contaminants in stormwater infiltration systems
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Edgehouse, Katelynn J., Ulrich, Bridget A., and Higgins, Christopher P.
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- 2017
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23. Benchmarking, Planning, and Promoting Transit- Oriented Intensification in Rapid Transit Station Areas: Project Key Indicators
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Higgins, Christopher D, Mahmoud, Moataz M, and Geography and Earth Sciences
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Rapid Transit ,Transit-Oriented Development - Abstract
As population and employment in the Greater Golden Horseshoe (GGH) region increase, there is a need to continue investing in rapid transit infrastructure to connect people and jobs, reduce harmful greenhouse gas emissions from transportation, and ensure that congestion does not negatively affect Ontario’s economic growth. But for rapid transit to have a meaningful impact on shaping travel patterns in the region, new and existing rapid transit infrastructure projects must be integrated with land use planning to promote transit-oriented development (TOD). TOD can offer a number of quality of life benefits for individuals, and for planners and policymakers, TOD is a great way to maximize the return on investment from existing and new rapid transit infrastructure. However, there cannot be a one-size-fits-all approach to TOD in the GGH. With more than 400 rapid transit stations either in existence or in various stages of planning, there is considerable diversity in station area contexts throughout the region. The present project develops and applies an innovative planning tool that distils station area characteristics into a typology of similar station types. Next, this tool is applied to benchmark TOD in present and future rapid transit station areas in the GGH, identifying TOD performance and contrasting this performance with existing and proposed policy and planning to identify areas that can benefit from more targeted interventions. Finally, the project uses the information from the typology to perform a detailed case study of the Hamilton A-Line and B-Line LRT. This project was produced by MITL with support from the Government of Ontario's Places to Grow Implementation Fund
- Published
- 2016
24. Benchmarking, Planning, and Promoting Transit-Oriented Intensification in Rapid Transit Station Areas
- Author
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Higgins, Christopher D and Geography and Earth Sciences
- Abstract
As population and employment in the Greater Golden Horseshoe (GGH) region increase, there is a need to continue investing in rapid transit infrastructure to connect people and jobs, reduce harmful greenhouse gas emissions from transportation, and ensure that congestion does not negatively affect Ontario’s economic growth. But for rapid transit to have a meaningful impact on shaping travel patterns in the region, new and existing rapid transit infrastructure projects must be integrated with land use planning to promote transit-oriented development (TOD). TOD can offer a number of quality of life benefits for individuals, and for planners and policymakers, TOD is a great way to maximize the return on investment from existing and new rapid transit infrastructure. However, there cannot be a one-size-fits-all approach to TOD in the GGH. With more than 400 rapid transit stations either in existence or in various stages of planning, there is considerable diversity in station area contexts throughout the region. The present project develops and applies an innovative planning tool that distils station area characteristics into a typology of similar station types. Next, this tool is applied to benchmark TOD in present and future rapid transit station areas in the GGH, identifying TOD performance and contrasting this performance with existing and proposed policy and planning to identify areas that can benefit from more targeted interventions. Finally, the project uses the information from the typology to perform a detailed case study of the Hamilton A-Line and B-Line LRT. This project was produced by MITL with support from the Government of Ontario's Places to Grow Implementation Fund
- Published
- 2016
25. Unbundling the Hedonic Price Effects of Rapid Transit and Transit-Oriented Development in Toronto
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Higgins, Christopher D. and Kanaroglou, Pavlos S.
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Public Economics - Abstract
Presented at the 51st CTRF (57th TRF) Joint Conference, May 1-4, 2016, Toronto, Ontario
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- 2016
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26. Investigating Molecular Mechanisms Underlying Morphogenetic Cell Shape Change
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Higgins, Christopher
- Abstract
Changes in cell shape are a fundamental feature of animal development driving the formation of ordered tissues from disordered groups of cells. One common type of animal cell shape change is apical constriction, where a cell or group of cells shrinks down one side more than others. Here, we seek to understand the molecular underpinnings that drive apical constriction using a simplified model system, the roundworm Caenorhabditis elegans. Early in C. elegans development, the endoderm precursor (E) cells undergo apical constriction. This cell shape change drives the internalization of the E cells. Previous work showed that the molecular motor non-muscle myosin II (NMY-2 in C. elegans) is required for E cell internalization, and is enriched and activated at the apical side of E cells where it is thought to generate force by pulling on a meshwork of filamentous actin in the cell cortex. We use particle image velocimetry to show that NMY-2 tagged with green fluorescent protein (GFP) localizes into distinct punctae which undergo centripetally-directed flow in the apical cortex of the E cells. We show that this flow occurs, surprisingly, before the initiation of cell shape change. We use laser nanosurgery to show that tension is established in the E cells’ apical cortices prior to cell shape change, that this tension does not change as cells change shape, and that this tension exceeds that of a neighboring, non-apically constricting cell. This work suggests that apical constriction may be governed not by the activation of myosin dynamics, but by a molecular clutch mechanically linking apical myosin dynamics to cell-cell junctions. We, therefore, sought to characterize the molecular nature of cell-cell junctions in the E cells to identify components that may contribute to this molecular clutch. We started by tagging with GFP all three essential members of the C. elegans cadherin-catenin complex (CCC), a complex known to contribute (albeit, redundantly) to apical constriction in the E cells. Spinning disk confocal fluorescence microscopy revealed that HMP-1/α-catenin-GFP, GFP-HMP-2/β-catenin, and HMR-1/cadherin-GFP all enriched at apical junctions as the E cells were undergoing apical constriction. We next showed that some CCC components require others to enrich apically. For example, HMR-1/cadherin requires HMP-1/α-catenin to enrich apically, suggesting that linking to the contractile actomyosin cytoskeleton might be required for apical enrichment. To test this we disrupted myosin dynamics using a temperature sensitive allele of nmy-2 or by using RNA interference to disrupt mrck-1, a kinase required for myosin activation. Both treatments disrupted the apical localization of cadherin, indicating that myosin activity is required to establish an apicobasally polarized cell-cell junction in apically constricting cells.
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- 2016
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27. A Value Planning Framework for Predicting and Recapturing the Value of Rapid Transit Infrastructure
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Higgins, Christopher, Kanaroglou, Pavlos, and Geography and Earth Sciences
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Greater Toronto and Hamilton Area ,Rapid Transit ,Transit-Oriented Development ,Value Planning ,Land Value Capture ,Land Value Uplift - Abstract
Land value capture (LVC) has been used to capitalize on the symbiotic relationship between rapid transit and its potential land value uplift (LVU) benefits for more than a century. For the public sector in particular, the rationale to engage in LVC to recapture the ‘unearned increment’ is strong. While interest in LVC has wavered over this time, planners and policymakers in Ontario and around the world are increasingly looking to value capture as a potential solution for raising more revenue to fund the construction and operation of rapid transit projects. However, significant theoretical, conceptual, and practical gaps remain in our knowledge of LVU and LVC that prevent the wider adoption of value capture as a strategy. First, a fundamental flaw in applications of LVC is that the value increment caused by rapid transit must to some degree be known a priori to set benchmark levels and ensure LVC tools capture the actual changes in land values caused by the project. Yet despite a rich history of research into the LVU benefits of rapid transit in cities around the world, a method for arriving at more empirical predictions of future LVU beyond simple approximation remains elusive. This leads to a second issue. Previous research into the LVU effects of rapid transit has produced a body of work that exhibits significant heterogeneity in results. Such diversity in research outcomes is due to a singular focus on expectations of LVU from rapid transit accessibility, which has led previous research to ignore the potential for additional land value impacts from sorting into different bundles of transit-oriented development (TOD) based on individual preferences. As such, the results of previous studies consider the value placed on a bundle of transit and TOD characteristics. This context-dependency makes them unsuitable for extensions to estimate the potential for LVC in future transit corridors. To overcome these issues, the present dissertation develops a value planning framework for rapid transit. This is accomplished through five objectives. First, Chapter 2 establishes a theoretical framework for understanding the LVU effects of rapid transit accessibility and TOD. Second, Chapter 3 develops a typology of station area TOD to reduce the complexity of station area heterogeneity and control for such contextual factors in further research. Third, Chapter 4 applies the TOD typology to unbundle the LVU effects of existing rapid transit in the City of Toronto. Fourth, Chapter 5 develops the value planning framework to better conceptualize the drivers of LVU benefits and capturable revenues, the policy interventions to maximize them, and the beginnings of a model to utilize unbundled estimates of LVU in other study areas to derive context-sensitive predictions of LVU in future transit station areas. Finally, Chapter 6 conducts a theoretical application of the value planning framework to the case of a light rail transit line in Hamilton, Ontario, to demonstrate a rationale for engaging in value planning to promote value capture. In accomplishing these objectives, the present dissertation makes a number of contributions to research and practice. However, it also raises a number of questions for future research. Nevertheless, this work presents a significant first step towards realizing research on rapid transit’s LVU effects that is more theoretically comprehensive and practical for better informing LVC planning and policy around the world. Dissertation Doctor of Philosophy (PhD)
- Published
- 2015
28. Truck Freight Generators & Attractors in the Province of Ontario
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Ferguson, Mark, Lavery, Tom, Higgins, Christopher, and Geography and Earth Sciences
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Freight Transportation ,Ontario, Canada - Abstract
This work is being carried out in partnership with the Ontario Ministry of Transportation as a follow up to a study that examined some of the more internationally-oriented freight generators in the Province. The purpose here is use available data sources to accurately screen out a large number of second-tier freight generators scattered throughout regions of the province and to perform a round of survey work to gather further details about each generator. NAmacsphere
- Published
- 2014
29. Emerging Contaminants from the Microscopic Perspective: The Effects of Perfluoroalkyl Substances on a Common Soil Microbe
- Author
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Weathers, Tess S, Higgins, Christopher P, and Sharp, Jonathan O
- Published
- 2013
- Full Text
- View/download PDF
30. OGC® Engineering Report for the OWS Shibboleth Interoperability Experiment
- Author
-
Higgins, Christopher
- Abstract
This document reports on outcomes from the OGC Web Services Shibboleth Interoperability Experiment (OSI). The main objective of OSI was to advance the use of Shibboleth (an open source implementation of SAML) as a means of protecting OWS. In the process, OSI helped develop further understanding of this approach to establishing trusted federations of OWS. This report documents these findings and is intended to be of use to those interested in how Shibboleth/SAML access management federations may function as an organisational model for operational Spatial Data Infrastructure.
- Published
- 2012
31. The North American Light Rail Experience: Insights for Hamilton
- Author
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Higgins, Christopher, Ferguson, Mark, and Geography and Earth Sciences
- Subjects
Light Rail Transit ,Hamilton, Ontario - Published
- 2012
32. Solubility of nano-zinc oxide in environmentally and biologically important matrices
- Author
-
Reed, Robert B., Ladner, David A., Higgins, Christopher P., Westerhoff, Paul, and Ranville, James F.
- Subjects
Solubility ,Surface Properties ,Nanoparticles ,Environment ,Particle Size ,Zinc Oxide ,Article ,Water Pollutants, Chemical - Abstract
Increasing manufacture and use of engineered nanoparticles (NPs) is leading to a greater probability for release of ENPs into the environment and exposure to organisms. In particular, zinc oxide (ZnO) is toxic, although it is unclear whether this toxicity is due to the zinc oxide nanoparticles (ZnO), dissolution to Zn2+, or some combination thereof. The goal of this study was to determine the relative solubilites of both commercially available and in-house synthesized ZnO in matrices used for environmental fate and transport or biological toxicity studies. Dissolution of ZnO was observed in nanopure water (7.18– 7.40 mg/L dissolved Zn, as measured by filtration) and Roswell Park Memorial Institute medium (RPMI-1640) (~5 mg/L), but much more dissolution was observed in Dulbecco’s Modified Eagle’s Medium (DMEM), where the dissolved Zn concentration exceeded 34 mg/L. Moderately hard water exhibited low zinc solubility, likely due to precipitation of a zinc carbonate solid phase. Precipitation of a zinc-containing solid phase in RPMI also appeared to limit zinc solubility. Equilibrium conditions with respect to ZnO solubility were not apparent in these matrices, even after more than 1,000 h of dissolution. These results suggest that solution chemistry exerts a strong influence on ZnO dissolution and can result in limits on zinc solubility due to precipitation of less soluble solid phases.
- Published
- 2012
33. An Exploration of the Freight Village Concept and its Applicability to Ontario
- Author
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Higgins, Christopher, Ferguson, Mark, and Geography and Earth Sciences
- Subjects
Freight Villages ,Logistics Centres - Abstract
This research was carried out for the Ontario Ministry of Transportation. The purpose of the research was to explore the concept of a freight village and provide some high level insights on the applicability of the concept in the province of Ontario. A freight village is an advanced form of logistics centre where a cluster of goods movement oriented and logistics facilities are co-located and co-ordinated to achieve synergies. Key attributes include an intermodal terminal, warehousing, manufacturing, wholesaling, logistics services and access to shared facilities, equipment and services. Centralized management and ownership and partnership between the public and private sectors are also central elements. In its pure form, a freight village can serve as an incubator for smaller logistics and related firms.
- Published
- 2011
34. Functional groupings of stream fishes: spatiotemporal variation, predictability, and patterns of diversity
- Author
-
Higgins, Christopher L., Wilde, Gene R., Schmidt, Kenneth A., Willig, Michael R., Winemiller, Kirk O., and Strauss, Richard E.
- Subjects
Functional gain ,Functional groups ,Biodiversity ,Macroecology ,Stream fish - Abstract
Biodiversity and ecosystem function is a contemporary topic at the forefront of ecology. It is driven by the fundamental need to understand how the loss of biodiversity, which is occurring all around the world, affects goods and services obtained from ecosystems. The scientific literature indicates functional attributes of species strongly influence ecosystem properties; however, a lack of understanding exists regarding the relationship among functional diversity, taxonomic diversity, and community structure. As a result, this dissertation contributes to our understanding of the relationship between biodiversity and ecosystem function by analyzing the organization of stream-fish assemblages from a functional and taxonomic perspective and by synthesizing the relationship between the two aspects of biodiversity. I used a combination of previously published data, which covered broad biogeographic areas, and my own field work to address various issues on multiple spatial and temporal scales. I focused exclusively on stream-fish assemblages because they are one of the most underrepresented groups of animals in biodiversity and ecosystem function research and because they play an important role in aquatic ecosystems by removing other plants and animals from the community, actively produce fragments or feces containing the bodies of their prey, and by mechanically disturbing substrates, thereby increasing suspension of materials in the water column. In general, I found functional redundancy within stream-fish assemblages, with functional groups dividing niche space more evenly than species whether looking at the entire state, ecoregions, river basins, or individual locations, and the spatial and temporal structure of stream-fish assemblages is similar for functional and taxonomic perspectives. These results indicate the need for future studies on biodiversity and ecosystem function to explicitly examine functional diversity, or at least incorporate functional attributes of individuals, in order to gain a holistic understanding.
- Published
- 2005
35. P-glycoprotein in blood-brain barrier endothelial cells: interaction and oligomerization with caveolins
- Author
-
Jodoin, Julie, Demeule, Michel, Fenart, Laurence, Cecchelli, Roméo, Farmer, Sarah, Linton, Kenneth J., Higgins, Christopher F., Béliveau, Richard, Laboratoire de Physiopathologie de la Barrière Hémato-Encéphalique (LBHE), Université d'Artois (UA), Medical Research Council, Imperial College London, Laboratoire de Médecine Moléculaire Ste-Justine-UQAM, Centre de Cancérologie Charles-Bruneau, Hôpital Ste-Justine-Université du Québec à Montréal = University of Québec in Montréal (UQAM), Service d'Hématologie-Oncologie, and Hôpital Ste-Justine
- Subjects
Caveolin ,Endothelial cell ,Brain ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,P-glycoprotein ,Caveolae ,Blood-brain barrier - Abstract
International audience; P-glycoprotein (P-gp), an adenosine triphosphate (ATP)-binding cassette transporter which acts as a drug efflux pump, is highly expressed at the blood–brain barrier (BBB) where it plays an important role in brain protection. Recently, P-gp has been reported to be located in the caveolae of multidrugresistant cells. In this study, we investigated the localization and the activity of P-gp in the caveolae of endothelial cells of the BBB. We used an in vitro model of the BBB which is formed by co-culture of bovine brain capillary endothelial cells (BBCEC) with astrocytes. Caveolar microdomains isolated from BBCEC are enriched in P-gp, cholesterol, caveolin-1, and caveolin-2. Moreover, P-gp interacts with caveolin-1 and caveolin-2; together, they form a high molecular mass complex. P-gp in isolated caveolae is able to bind its substrates, and the caveolae-disrupting agents filipin III and nystatin decrease P-gp transport activity. In addition, mutations in the caveolin-binding motif present in P-gp reduced the interaction of P-gp with caveolin-1 and increased the transport activity of P-gp. Thus, P-gp expressed at the BBB is mainly localized in caveolae and its activity may be modulated by interaction with caveolin-1.
- Published
- 2003
36. Bacterial multidrug resistance mediated by ABC transporters
- Author
-
Poelarends, Gerrit J., Vigano, C, Ruysschaert, J.M., Konings, W.N, Holland, Barry, Cole, Susan, Kuchler, Karl, Higgins, Christopher, Biopharmaceuticals, Discovery, Design and Delivery (BDDD), and Medicinal Chemistry and Bioanalysis (MCB)
- Subjects
ABC transport system - Published
- 2003
37. Das Glück des Lehrers
- Author
-
Higgins, Christopher
- Subjects
Ethik ,Erziehung, Schul- und Bildungswesen ,Berufsethos ,Schulpädagogik ,Egoism ,370 Erziehung, Schul- und Bildungswesen ,Morals ,Education ,Lehrerrolle ,ddc:370 ,Rollenerwartung ,Sonstige ,Role expectation ,Glück ,Lehrer ,Teacher's role ,Ethics ,Motivation ,Williams, Bernard ,Teacher ,Altruismus ,Moral ,Philosophie ,Altruism ,Teacher role ,FOS: Philosophy, ethics and religion ,Philosophy ,Bliss ,Egoismus ,370 Education - Abstract
Zeitschrift für Pädagogik 48 (2002) 4, S. 495-513, Im Rückgriff auf Bernard Williams' Unterscheidung zwischen Ethik und Moral [vertritt der Autor] die These, dass die Ethik des Lehrens sich mit der Beziehung zwischen dem Leben, dass [man] als Lehrer(in) führt, und dem guten Leben beschäftigt. Die Ethik des Lehrens führt die Frage: "Warum lehre ich?" mit der Frage: "Wie möchte ich leben?" zusammen. Die moderne Gegenüberstellung von egoistischem Interesse und Altruismus führt zu einer Vernachlässigung des Wohlergehens des Lehrers / der Lehrerin. [Der Autor plädiert dafür], diese moralische Kurzsichtigkeit [zu] verlassen um zu fragen: Warum ist die Praxis des Lehrens es wert, dass sie im Zentrum meines Lebens steht? Wie bringt mich das Lehren zu den Gütern in Verbindung, die ich am meisten schätze? Wie unterstützt meine Sorge um Wachstum anderer auch mein Wachstum? (DIPF/Orig.), Using Bernard Williams' ethics/morality distinction, I argue that the ethics of teaching concerns the relation between the teaching life and the good life, connecting the question "why teach?" with the question "how should I live?" The modern dichotomy between self-interest and altruism leads us to neglect the flourishing of the teacher. We must transcend this moral myopia to ask: Why is the practice of teaching worth putting at the center of my life? How does teaching put me in touch with the goods I prize most? How does tending to the growth of others nourish my own growth? (DIPF/Orig.)
- Published
- 2002
- Full Text
- View/download PDF
38. Discrimination of foraging paths produced by different search tactics
- Author
-
Higgins, Christopher L.
- Subjects
Forage ,Animals ,Animal behavior - Abstract
Search tactics are cognitive processes, or decision mechanisms, that organisms utilize to elicit a group of related and sequential behaviors that allow them to locate available resources such as food, mates, refugia, and habitats. However, our knowledge of the actual tactics that animals utilize while searching for resources is limited, and very little empirical evidence has been gathered. As a result, a suite of models of theoretical search tactics was developed to emulate the searching behaviors of mobile individuals so that inferences might be made about their decision mechanisms, and to determine whether individuals are capable of searching with a globally optimal solution. The theoretical tactics included four deterministic tactics (maximum-distance search, minimum-distance search, nearest-neighbor search, and trajectory-directed search) and five probabilistic tactics (reciprocal-distance search, inverse-squared-distance search, uniformly random search, Pearson random walk, and Levy random walk). These tactics included variations of random walks and systematic searches in an attempt to characterize biologically realistic searching behaviors. The theoretical search tactics were simulated with hypothetical predators finding and consuming the same sets of resources, assuming no satiation or learning, so that comparisons among the resulting search paths could be made. Correlated measures of path length, consistency of movement, path linearity and turn rate were used to characterize the geometry of the resulting search paths. Classieal multivariate analysis, including discriminant function analysis (DFA) and non-linear artificial neural networks (ANN), were used to discriminate among the theoretical tactics and to classify "unknown" search paths into one of the underlying search tactics, both based on the geometry of the resulting paths. Both linear and non-linear discriminatory anah ses revealed a strong overlap between the nearest-neighbor search and the minimum-distance search tactics. This overlap implies that it is possible for animals to utilize search tactics that mirror the globally optimal solution without having complete knowledge of the specific location of available resources. Furthermore, both methods of analyses demonstrated that inferences could be made about the actual tactics that animals utilize while searching for resources based on the geometry of the search paths, but with varying degrees of reliability.
- Published
- 2001
39. Comparative assessment of fluorescent proteins for in vivo imaging in an animal model system
- Author
-
Heppert, Jennifer K, Dickinson, Daniel J, Pani, Ariel M, Higgins, Christopher D, Steward, Annette, Ahringer, Julie, Kuhn, Jeffrey R, and Goldstein, Bob
- Subjects
Disease Models, Animal ,Luminescent Proteins ,Microscopy, Fluorescence ,Green Fluorescent Proteins ,Optical Imaging ,Animals ,Caenorhabditis elegans ,3. Good health ,Fluorescent Dyes - Abstract
Fluorescent protein tags are fundamental tools used to visualize gene products and analyze their dynamics in vivo. Recent advances in genome editing have expedited the precise insertion of fluorescent protein tags into the genomes of diverse organisms. These advances expand the potential of in vivo imaging experiments and facilitate experimentation with new, bright, photostable fluorescent proteins. Most quantitative comparisons of the brightness and photostability of different fluorescent proteins have been made in vitro, removed from biological variables that govern their performance in cells or organisms. To address the gap, we quantitatively assessed fluorescent protein properties in vivo in an animal model system. We generated transgenic Caenorhabditis elegans strains expressing green, yellow, or red fluorescent proteins in embryos and imaged embryos expressing different fluorescent proteins under the same conditions for direct comparison. We found that mNeonGreen was not as bright in vivo as predicted based on in vitro data but is a better tag than GFP for specific kinds of experiments, and we report on optimal red fluorescent proteins. These results identify ideal fluorescent proteins for imaging in vivo in C. elegans embryos and suggest good candidate fluorescent proteins to test in other animal model systems for in vivo imaging experiments.
40. Comparative assessment of fluorescent proteins for in vivo imaging in an animal model system
- Author
-
Higgins, Christopher D., Kuhn, Jeffrey R., Goldstein, Bob, Steward, Annette, Dickinson, Daniel J., Ahringer, Julie, Pani, Ariel M., and Heppert, Jennifer K.
- Subjects
3. Good health - Abstract
Fluorescent protein tags are fundamental tools used to visualize gene products and analyze their dynamics in vivo. Recent advances in genome editing have expedited the precise insertion of fluorescent protein tags into the genomes of diverse organisms. These advances expand the potential of in vivo imaging experiments and facilitate experimentation with new, bright, photostable fluorescent proteins. Most quantitative comparisons of the brightness and photostability of different fluorescent proteins have been made in vitro, removed from biological variables that govern their performance in cells or organisms. To address the gap, we quantitatively assessed fluorescent protein properties in vivo in an animal model system. We generated transgenic Caenorhabditis elegans strains expressing green, yellow, or red fluorescent proteins in embryos and imaged embryos expressing different fluorescent proteins under the same conditions for direct comparison. We found that mNeonGreen was not as bright in vivo as predicted based on in vitro data but is a better tag than GFP for specific kinds of experiments, and we report on optimal red fluorescent proteins. These results identify ideal fluorescent proteins for imaging in vivo in C. elegans embryos and suggest good candidate fluorescent proteins to test in other animal model systems for in vivo imaging experiments.
41. Computer Modelling of English Grammar
- Author
-
Ritchie, Graeme D., Longuet-Higgins, Christopher, and Dewar, Hamish
- Subjects
TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES ,computer science - Abstract
Recent work in artificial intelligence has developed a number of techniques which are particularly appropriate for constructing a model of the process of understanding English sentences. These methods are used here in the definition of a framework for linguistic description, called "computational grammar". This framework is employed to explore the - details of the operations involved in transforming an representation English sentence into a general semantic Computational grammar includes both "syntactic" and "semantic" constructs, in order to clarify the interactions between all the various kinds of information, and treats the sentence-analysis process as having a semantic goal which may require syntactic means to achieve it. The sentence-analyser is based on the concept of an "augmented transition network grammar", modified to minimise unwanted top-down processing and unnecessary era bedding. The analyser does not build a purely syntactic ,structure for a sentence, but the semantic rules operate hierarchically in a way which reflects the traditional tree structure. The processing operations are simplified by using temporary storage to postpone premature decisions or to conflate different options. The computational grammar framework has been applied to a few areas of English, including relative clauses, referring expressions, verb phrases and tense. A computer program ( "MCHINE") has been written which implements the constructs of computational grammar and some of the linguistic descriptions of English. A number of sentences have been successfully processed by the program, which can carry on a simple. dialogue as well as building semantic representations for isolated sentences .
- Published
- 1977
42. Relaxation and its Role in Vision
- Author
-
Hinton, Geoffrey E. and Longuet-Higgins, Christopher
- Subjects
computer science - Abstract
It is argued that a visual system, especially one which handles imperfect data, needs a way of selecting the best consistent combination from among the many interrelated, locally plausible hypotheses about how parts or aspects of the visual input may be interpreted. A method is presented in which each hypothesis is given a supposition value between 0 and 1. A parallel relaxation I operator, based on the plausibilities of hypotheses and the logical relations between them, is then used to modify the supposition values, and the process is repeated until the best consistent set of hypotheses have supposition values of approximately 1, and the rest have values of approximately 0. The method is incorporated in a program which can interpret configurations of overlapping rectangles as puppets. For this task it is possible to formulate all the potentially relevant hypotheses before using relaxation to select the best consistent set. For more complex tasks, it is necessary to use relaxation on the locally plausible interpretations to guide the search for locally less obvious ones. Ways of doing this are discussed. Finally, an implemented system is presented which allows the user to specify schemas and inference rules, and uses relaxation to control the building of a network of instances of the schemas, when presented with data about some instances and relations between them
- Published
- 1977
43. The formal description of musical perception
- Author
-
Steedman, Mark and Longuet-Higgins, Christopher
- Subjects
computer science - Abstract
This work concerns a problem in modelling people's understanding of music. The problem is cast in the terms of discovering formal rules for transcribing melodies into musical notation, as this might be done by a student in a harmony class, taking musical dictation from a 'deadpan' performance on the keyboard. The score that results reflects important aspects of the structure and interpretation of the piece, which are only implicit in the performance. In Part I it is argued that this paradigm raises questions of general relevance to the study of our perception of music. In carrying out the task of notating a piece, two kinds of problem arise: what are the harmonic relations between the notes, and what are the metric units into which they are grouped? These two problems are considered in isolation from one another. In Part II, algorithms which embody two kinds of rule for the inference of metre are presented . In Part III the harmonic problem is considered. It arises from the fact that the number of keyboard semitones between two notes does not, by itself, identify their harmonic relation, which is what the notation has to express. Among other considerations, the key of the piece is an important characterisation of this identification - but the key is not explicit in the performance, and must itself be inferred. An earlier theory of harmonic relations is further developed into algorithms for assigning key-signatures and notation to melodies. By -the definition of the problem, we are committed to the concern of music belonging to the tradition of Western tonal music, to which the idea of key applies. Most of' the musical examples discussed will be taken from the work of one of its outstanding exponents, J.S. Bach, and in particular we shall be dealing with the fugue subjects of his “Well-Tempered Clavier". Some of the contents of Part II, Section § 2, and of Part III, Section § 3, have already appeared in a paper published in collaboration with H.C. Longuet-Higgins. Part III, Section § 2.1, describes his prior work in formulating the theory of harmonic relations, mentioned above, which forms the foundation of the work described in that section and has been published elsewhere by him.
- Published
- 1972
44. Models of Distributed Associative Memory
- Author
-
Willshaw, David and Longuet-Higgins, Christopher
- Subjects
Annexe Thesis Digitisation Project 2016 Block 3 ,computer science - Abstract
This work is concerned with the problem of constructing associative memory models which store and retrieve information in a distributed fashion - that is each store location can be involved in the storage of more than one piece of information. The models are to be logically simple in form and efficient in their use of store. It is hoped that those proposed may find a place in neurophysiological theories of memory. From the starting point of seeking a less complex representation of a holographic model of memory called the Holophone, several memory models have been proposed and their properties investigated by analytical and computer simulation methods. All the systems considered belong to a family of memory models which are described by a pair of matrix equations. It is found that the models which perform well are non-linear devices which have to store and retrieve highly redundant information. One of these, the Associative Net, is closely related to a recent theory of the cerebellum. Some of the contents of Chapters 3, 4 and 5 have already appeared in papers published in collaboration with H.C. Longuet-Higgins and O.P. Buneman. Otherwise this dissertation is believed to be original in content and in arrangement.
- Published
- 1971
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