2,592 research outputs found
Shaping 21st Century Journalism: Leveraging a "Teaching Hospital Model" in Journalism Education
Calls on journalism programs to become "anchor institutions" in the digitally networked age by pursuing a broader, community-oriented mission, testing new journalism models, exploring how journalistic ecosystems evolve, and shaping policymaking processes
Cytogenomic Analyses of the genus Sorghum
A phylogenetic tree based on ITS1, Adh1 and ndhF grouped the species of the
genus Sorghum into one distinct monophyletic group, but including two sister lineages,
one with x=5, the other with x=10 as basic chromosome numbers. The goal of this study was to elucidate major patterns in Sorghum genome evolution, particularly n=5 vs. n=10 genomes. A very recent molecular cytogenetic study in our laboratory revealed striking structural karyotypic rearrangements between S. bicolor (x=10) and an x=5 Sorghum species, S. angustum; so an immediate objective here was to determine if identical or similar rearrangements exist in other wild Sorghum species. Our approach was [1] to extend similar methods to additional species, i.e., fluorescent in situ hybridization (FISH) analyses of sorghum genomic bacterial artificial chromosome clones and multi-BAC cocktail probes to mitotic chromosomes of S. angustum, S. versicolor, S. brachypodum and S. intrans; and [2] to augment the BAC-FISH findings by comparing telomeric and ribosomal DNA FISH signal distributions to x=5 and x=10 Sorghum species. Signals from in situ hybridizations of BAC-based probes were insufficiently robust and insufficiently localized to delineate FISH signal patterns akin to those discovered previously in S. angustum. Southern blots of the same BACs to restricted DNA of these species revealed relatively moderate affinity to smeared DNA, suggesting homology to non-tandemized sequences. FISH of the A-type TRS (Arabidopsis-like telomeric repeat sequence) revealed its presence is limited to terminal chromosomal regions of the Sorghum species tested, except S. brachypodum, which displayed intercalary signal on one chromosome and no detachable signal at its termini region. The hybridization of 45S and 5S rDNA revealed that the respective sites of tandemized clusters differ among species in terms of size, number and location, except S. angustum versus S. versicolor.
Well localized BAC-FISH signals normally occur when signals from low-copy sequences discernibly exceed background signal, including those from hybridization of dispersed repetitive elements. The low level of signal intensity from BAC low-copy sequences relative to the background signal "noise" seems most likely due to low homology and(or) technical constraints. Extensive dispersal of low-copy sequences that are syntenic in S. bicolor seems unlikely, but possible.
In conclusion, the result was a lack of clear experimental success with BAC-FISH and an inability to effectively screen for S. angustum-like rearrangements using BAC-FISH. The telomeric and rDNA FISH indicated that the x=5 genomes vary extensively. One can surmise that although the arrangements seen in S. angustum might extend to S. versicolor, they certainly do not extend to S. versicolor, they certainly do not extend to S. intrans or S. brachypodum. It is clear that S. brachypodum has telomeric repeats that are either very short or rely on some sequence other than the A-type TRS
Speed Management and Speed Reduction in Portland, OR
In 2015, the Portland City Council unanimously passed a resolution committing Portland to Vision Zero, the goal to eliminate traffic deaths and serious injuries. An underpinning of Vision Zero is that streets are managed for safe speeds. This presentation will summarize Portland\u27s speed management process, how it relates to achieving Vision Zero, and present two case studies in which speed limits were reduced: (1) a 25 mi/h to 20 mi/h reduction on residential streets and (2) various reductions on arterials and collectors. Reduction sites in which additional treatments were implemented, such as speed humps and fixed speed safety cameras, will also be discussed. Results of the data analysis will be shared, along with next steps in Portland\u27s speed management process.https://pdxscholar.library.pdx.edu/trec_seminar/1229/thumbnail.jp
Understanding Factors Affecting Arterial Reliability Performance Metrics
In recent years, the importance of travel time reliability has become equally important as average travel time. However, the majority focus of travel time research is average travel time or travel time reliability on freeways. In addition, the identification of specific factors (i.e., peak hours, nighttime hours, etc.) and their effects on average travel time and travel time variability are often unknown. The current study addresses these two issues through a travel time-based study on urban arterials. Using travel times collected via Bluetooth data, a series of analyses are conducted to understand factors affecting reliability metrics on urban arterials. Analyses include outlier detection, a detailed descriptive analysis of select corridors, median travel time analysis, assessment of travel time reliability metrics recommended by the Federal Highway Administration (FHWA), and a bivariate Tobit model. Results show that day of the week, time of day, and holidays have varying effects on average travel time, travel time reliability, and travel time variability. Results also show that evening peak hours have the greatest effects in regards to increasing travel time, nighttime hours have the greatest effects in regards to decreasing travel time, and directionality plays a vital role in all travel time-related metrics
A Temporal Investigation of Crash Severity Factors in Worker-Involved Work Zone Crashes: Random Parameters and Machine Learning Approaches
In the context of work zone safety, worker presence and its impact on crash severity has been less explored. Moreover, there is a lack of research on contributing factors by time-of-day. To accomplish this, first a mixed logit model was used to determine statistically significant crash severity contributing factors and their effects. Significant factors in both models included work-zone-specific characteristics and crash-specific characteristics, where environmental characteristics were only significant in the daytime model. In addition, results from parameter transferability test provided evidence that daytime and nighttime crashes need to be modeled separately. Further, to explore the nonlinear relationship between crash severity levels and time-of-day, as well as compare the effects of variables to that of the logit model and assess prediction performance, a Support Vector Machines (SVM) model trained by Cuckoo Search (CS) algorithm was utilized. Opening the SVM black-box, a variable impact analysis was also performed. In addition to the characteristics identified in the logit models, the SVM models also included the impacts of vehicle-level characteristics. The variable impact analysis illustrated that the termination area of the work zone is most critical for both daytime and nighttime crashes, as this location has the highest increase in severe injury likelihood. In summary, results of this study demonstrate that work zone crashes need to be modeled separately by time-of-day with a high level of confidence. Furthermore, results show that the CS-SVM models provide better prediction performance compared to the SVM and logit models
Using Temporal Changes in Drought Indices to Generate Probabilistic Drought Intensification Forecasts
In this study, the potential utility of using rapid temporal changes in drought indices to provide early warning of an elevated risk for drought development over subseasonal time scales is assessed. Standardized change anomalies were computed each week during the 2000–13 growing seasons for drought indices depicting anomalies in evapotranspiration, precipitation, and soil moisture. A rapid change index (RCI) that encapsulates the accumulated magnitude of rapid changes in the weekly anomalies was computed each week for each drought index, and then a simple statistical method was used to convert the RCI values into drought intensification probabilities depicting the likelihood that drought severity as analyzed by the U.S. Drought Monitor (USDM) would worsen in subsequent weeks. Local and regional case study analyses revealed that elevated drought intensification probabilities often occur several weeks prior to changes in the USDM and in topsoil moisture and crop condition datasets compiled by the National Agricultural Statistics Service. Statistical analyses showed that the RCI-derived probabilities are most reliable and skillful over the central and eastern United States in regions most susceptible to rapid drought development. Taken together, these results suggest that tools used to identify areas experiencing rapid changes in drought indices may be useful components of future drought early warning systems
Cytogenomic Analyses of the genus Sorghum
A phylogenetic tree based on ITS1, Adh1 and ndhF grouped the species of the
genus Sorghum into one distinct monophyletic group, but including two sister lineages,
one with x=5, the other with x=10 as basic chromosome numbers. The goal of this study was to elucidate major patterns in Sorghum genome evolution, particularly n=5 vs. n=10 genomes. A very recent molecular cytogenetic study in our laboratory revealed striking structural karyotypic rearrangements between S. bicolor (x=10) and an x=5 Sorghum species, S. angustum; so an immediate objective here was to determine if identical or similar rearrangements exist in other wild Sorghum species. Our approach was [1] to extend similar methods to additional species, i.e., fluorescent in situ hybridization (FISH) analyses of sorghum genomic bacterial artificial chromosome clones and multi-BAC cocktail probes to mitotic chromosomes of S. angustum, S. versicolor, S. brachypodum and S. intrans; and [2] to augment the BAC-FISH findings by comparing telomeric and ribosomal DNA FISH signal distributions to x=5 and x=10 Sorghum species. Signals from in situ hybridizations of BAC-based probes were insufficiently robust and insufficiently localized to delineate FISH signal patterns akin to those discovered previously in S. angustum. Southern blots of the same BACs to restricted DNA of these species revealed relatively moderate affinity to smeared DNA, suggesting homology to non-tandemized sequences. FISH of the A-type TRS (Arabidopsis-like telomeric repeat sequence) revealed its presence is limited to terminal chromosomal regions of the Sorghum species tested, except S. brachypodum, which displayed intercalary signal on one chromosome and no detachable signal at its termini region. The hybridization of 45S and 5S rDNA revealed that the respective sites of tandemized clusters differ among species in terms of size, number and location, except S. angustum versus S. versicolor.
Well localized BAC-FISH signals normally occur when signals from low-copy sequences discernibly exceed background signal, including those from hybridization of dispersed repetitive elements. The low level of signal intensity from BAC low-copy sequences relative to the background signal "noise" seems most likely due to low homology and(or) technical constraints. Extensive dispersal of low-copy sequences that are syntenic in S. bicolor seems unlikely, but possible.
In conclusion, the result was a lack of clear experimental success with BAC-FISH and an inability to effectively screen for S. angustum-like rearrangements using BAC-FISH. The telomeric and rDNA FISH indicated that the x=5 genomes vary extensively. One can surmise that although the arrangements seen in S. angustum might extend to S. versicolor, they certainly do not extend to S. versicolor, they certainly do not extend to S. intrans or S. brachypodum. It is clear that S. brachypodum has telomeric repeats that are either very short or rely on some sequence other than the A-type TRS
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Unobserved Heterogeneity and Spatial Correlation: Statistical and Econometric Analyses of Heavy-Vehicle Hard Braking and Crash Frequency by Crash Type
This dissertation provides a comparison of statistical and econometric frameworks, using a previously unused freight data source, to study crash frequency by crash type and heavy-vehicle hard braking in Oregon. Hard braking can serve as a proxy for several factors, one of which is safety. Therefore, with the hard braking literature being limited to regenerative braking of electric vehicles, behavior modeling, and stopping performance, this dissertation uniquely fills the gap in literature as it pertains to hard braking of heavy-vehicles explicitly in a safety context. Hence, based on the data, the four most occurring crash types at areas prone to heavy-vehicle hard braking are analyzed: rear-end crashes, turning movement crashes, fixed-object crashes, and sideswipe (overtaking) crashes.
The new norm in transportation safety analyses is to account for the unobserved heterogeneity (unobservables) in the crash data. However, specific events may be linked spatially, which can result in spatial correlation. With this in mind, this dissertation seeks to analyze each crash type by fitting a model that accounts for unobserved heterogeneity and a model that accounts for spatial correlation. This is accomplished through a detailed data process and spatial analysis. To compare these analytic methods, overall model fit (log-likelihood values) and the rate of correctly predicted crash frequencies are assessed. With crash frequencies being non-negative integer count values, specific count-data models are applied: Poisson regression if the data is not over- or under-dispersed, Negative Binomial regression if the data is over- or under-dispersed, and Spatial Lag of X variants of these models if there is significant spatial correlation. Results show that three of the four crash frequency models have a better fit when accounting for spatial autocorrelation. But, the rate of correctly predicted crash frequencies for each crash type is substantially higher when accounting for unobserved heterogeneity.
As stated previously, through the comparison of the crash frequency analysis frameworks, the predictability power of the “heterogeneity” models outperformed the predictability of the spatial models. In addition to identifying a preferred method to model crash frequency, this dissertation shows the viability of a new freight data source for transportation research. More, the importance of studies regarding hard braking and crash frequency have been presented. This dissertation uniquely fills this gap in literature.
Finally, an analytical foundation and recommendations have been provided. With regard to the analytical method, several Departments of Transportation (DOT) use traditional crash frequency analysis methods; but, they typically do not account for unobserved heterogeneity. This work has shown that the Oregon DOT (location of the current study) can generate a higher rate of prediction by accounting for these unobservables in crash data. For recommendations, this dissertation identifies methods to monitor hard braking (both for heavy-vehicles and other classes of vehicles). In addition, the locations of heavy-vehicle hard braking hot spots, along with the significant crash frequency contributing factors, can assist the Oregon DOT in identifying specific countermeasures to mitigate hard braking events and crash frequency by crash type
Soil-less Agriculture at the Wat Pathumwanaram School: Expansion through an Aeroponic Garden and Educational Material
Working in a multinational team with students from a Thai university, we created an aeroponic garden for the Wat Pathumwanaram School\u27s soil-less agriculture program. Further, we created educational material to teach the practices of soil-less agriculture. These two objectives help the school demonstrate the role of soil-less agriculture as a sustainable technology. To develop the aeroponic garden we used engineering design, guiding us to a feasible solution to meet the needs of the school. In developing the curricular materials, we defined goals and outcomes that were matched to practices already used. This ensured that the changes could be seamlessly integrated into daily practice. Overall, we were able to help demonstrate the potential that technology has to meet the needs of a society
Knowledge-based vision and simple visual machines
The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the knowledge-based vision approach in the understanding of evolved systems (machines or animals) may well lead to theories and models that are internally consistent, computationally plausible, and entirely wrong
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