5,825 research outputs found
Making sense of the manufacturing belt : determinants of U.S. industrial location, 1880-1920
This paper investigates the ability of the new economic geography to explain the persistence of the manufacturing belt in the United States around the turn of the 20th century using a model which subsumes both market-potential and factor-endowment arguments. The results show that market potential was central to the existence of the manufacturing belt, that it mattered more than factor endowments, and that its impact
came through interactions both with scale economies and with linkage effects. Natural advantage played a role in industrial location but only through agricultural inputs which were important for a small subset of manufacturing
Computational Urban Planning: Using the Value Lab as Control Center
Urban planning involves many aspects and various disciplines, demanding an asynchronous planning approach. The level of complexity rises with each aspect to be considered and makes it difficult to find universally satisfactory solutions. To improve this situation we propose a new approach, which complement traditional design methods with a computational urban plan- ning method that can fulfil formalizable design requirements automatically. Based on this approach we present a design space exploration framework for complex urban planning projects. For a better understanding of the idea of design space exploration, we introduce the concept of a digital scout which guides planners through the design space and assists them in their creative explorations. The scout can support planners during manual design by informing them about potential im- pacts or by suggesting different solutions that fulfill predefined quality requirements. The planner can change flexibly between a manually controlled and a completely automated design process. The developed system is presented using an exemplary urban planning scenario on two levels from the street layout to the placement of building volumes. Based on Self-Organizing Maps we implemented a method which makes it possible to visualize the multi-dimensional solution space in an easily analysable and comprehensible form
Lightweight urban computation interchange (LUCI) system
In this paper we introduce LUCI, a Lightweight Urban Calculation Interchange system, designed to bring the advantages of a calculation and content co-ordination system to small planning and design groups by the means of an open source middle-ware. The middle-ware focuses on problems typical to urban planning and therefore features a geo-data repository as well as a job runtime administration, to coordinate simulation models and its multiple views. The described system architecture is accompanied by two exemplary use cases that have been used to test and further develop our concepts and implementations
A Recurrent Neural Network Survival Model: Predicting Web User Return Time
The size of a website's active user base directly affects its value. Thus, it
is important to monitor and influence a user's likelihood to return to a site.
Essential to this is predicting when a user will return. Current state of the
art approaches to solve this problem come in two flavors: (1) Recurrent Neural
Network (RNN) based solutions and (2) survival analysis methods. We observe
that both techniques are severely limited when applied to this problem.
Survival models can only incorporate aggregate representations of users instead
of automatically learning a representation directly from a raw time series of
user actions. RNNs can automatically learn features, but can not be directly
trained with examples of non-returning users who have no target value for their
return time. We develop a novel RNN survival model that removes the limitations
of the state of the art methods. We demonstrate that this model can
successfully be applied to return time prediction on a large e-commerce dataset
with a superior ability to discriminate between returning and non-returning
users than either method applied in isolation.Comment: Accepted into ECML PKDD 2018; 8 figures and 1 tabl
An Experimental Framework to Examine the Influence of Promoter Architecture and Genomic Context on Gene Expression
Transcription is a fundamental process of gene expression. Information stored in DNA is transcribed into different types of mobile RNA, which play a role in various essential processes of the cell, e.g. translation. However, cells do not need all the information stored in their DNA at the same time. Therefore, the process of transcription gets regulated by a plethora of mechanisms. One frequently discussed but poorly understood mechanism of transcription regulation is DNA supercoiling [Travers and Muskhelishvili, 2005]. Whereby, the process of transcription itself affects the DNA-topology up- and downstream of the transcription machinery as described in the twin supercoiling domain model [Liu and Wang, 1987]. This phenomenon is called Transcription Coupled DNA Supercoiling (TCDS). It has also been shown that genes react individually to changes in DNA supercoiling and that there is a selection pressure on adapting to the DNA supercoiling levels emitted by neighbouring gene expression [Sobetzko, 2016]. The system in which promoters react to changes in DNA supercoiling is as diverse as there are promoters; notably, some promoters seem not to respond to DNA supercoiling at all. Thus, this raises the question as to which elements within different promoter types cause them to respond to TCDS so differently. In this thesis, I built a pipeline to investigate the effects of TCDS and DNA supercoiling on promoters. Firstly, I created a plasmid toolbox, which allows modular assembly of transcription units. The central feature of this toolbox is the flexibility to test different arrangements of multiple transcription units. I achieved this by adapting the well established Modular Cloning (MoClo) standard [Weber et al., 2011] and build my toolbox around it. I thus created a system that works on both its own and is compatible with the existing standard MoClo protocol.
In the second part of this thesis, I established an experimental pipeline using synthetic Ï70-promoters to investigate the influence of DNA supercoiling on transcription. The experimental setup allowed precise changes in parts of the promoter and at the same time created a library of these promoters. Using this pipeline to investigate the spacer region of the promoter, I was able to confirm that the spacer influences the promoter strength. Further, I showed that the promoter spacer has only a limited effect on the supercoiling sensitivity of a promoter. I also showed that a 5â-TGTG-3â motif in the spacer region could lower transcription by enhancing RNA-polymerase (RNAP)-binding. Moreover, the experimental setup also showed the constraints of using the DNA-relaxing drug novobiocin on a plasmid-based system. Hence, to further investigate the effects of TCDS on neighbouring transcription, I applied an optogenetically-controllable promoter to the previously established pipeline. Finally, I began to explore the possibility of integrating my experimental promoter setup into any genomic position. As such, a CRISPR/Cas9-based homologous re-combination system was developed further to make it modular and compatible with the Modular Cloning protocol. I could show the first features of this system to work
How Sex Offenders are Causing Unneeded Moral Panic in the Current Day
4th Annual Lyceum at The University of Texas at Tylerhttps://scholarworks.uttyler.edu/student_posters/1034/thumbnail.jp
Comparison of Written and Spoken Instruction to Foster Coordination between Diagram and Equation in Undergraduate Physics Education
Visualâgraphical representations are used to visualise information and are therefore key components of learning materials. An important type of convention-based representation in everyday contexts as well as in science, technology, engineering, and math (STEM) disciplines are vector field plots. Based on the cognitive theory of multimedia learning, we aim to optimize an instruction with symbolical-mathematical and visual-graphical representations in undergraduate physics education through spoken instruction combined with dynamic visual cues. For this purpose, we conduct a pre-post study with 38 natural science students who are divided into two groups and instructed via different modalities and with visual cues on the graphical interpretation of vector field plots. Afterward, the students rate their cognitive load. During the computer-based experiment, we record the participantsâ eye movements. Our results indicate that students with spoken instruction perform better than students with written instruction. This suggests that the modality effect is also applicable to mathematical-symbolical and convention-based visual-graphical representations. The differences in visual strategies imply that spoken instruction might lead to increased effort in organising and integrating information. The finding of the modality effect with higher performance during spoken instruction could be explained by deeper cognitive processing of the material
Visual cues improve studentsâ understanding of divergence and curl: Evidence from eye movements during reading and problem solving
The coordination of multiple external representations is important for learning, but yet a difficult task for students, requiring instructional support. The subject in this study covers a typical relation in physics between abstract mathematical equations (definitions of divergence and curl) and a visual representation (vector field plot). To support the connection across both representations, two instructions with written explanations, equations, and visual representations (differing only in the presence of visual cues) were designed and their impact on studentsâ performance was tested. We captured studentsâ eye movements while they processed the written instruction and solved subsequent coordination tasks. The results show that students instructed with visual cues (VC students) performed better, responded with higher confidence, experienced less mental effort, and rated the instructional quality better than students instructed without cues. Advanced eye-tracking data analysis methods reveal that cognitive integration processes appear in both groups at the same point in time but they are significantly more pronounced for VC students, reflecting a greater attempt to construct a coherent mental representation during the learning process. Furthermore, visual cues increase the fixation count and total fixation duration on relevant information. During problem solving, the saccadic eye movement pattern of VC students is similar to experts in this domain. The outcomes imply that visual cues can be beneficial in coordination tasks, even for students with high domain knowledge. The study strongly confirms an important multimedia design principle in instruction, that is, that highlighting conceptually relevant information shifts attention to relevant information and thus promotes learning and problem solving. Even more, visual cues can positively influence studentsâ perception of course materials
Die Demethylierung von Dimethylselenid ist eine adaptive Antwort des Archaeons Methanococcus voltae
Im natĂŒrlichen Lebensraum von Methanococcus voltae
kommt Selen in unterschiedlichen Verbindungen und Konzentration
vor. So variiert der Selengehalt im MĂŒndungswasser
verschiedener FlĂŒsse zwischen 0,1 und 63 nM. Aufgrund der guten
Löslichkeit sind die Oxianionen des Selens biologisch am
interessantesten. Sie sind daher aber auch in hohen
Konzentrationen toxisch. Selen in geringen Mengen ist dagegen
essentiell, da es als Selenomethionin oder -cystein in
Proteinen vorkommen kann. Eine hÀufig anzutreffende organische
Selenverbindungen ist das Dimethylselenid (DMSe). Diese
flĂŒchtige Substanz wird von einer Vielzahl Organismen zur
Detoxifizierung gebildet. Aus M. voltae sind insgesamt 4
Hydrogenasen bekannt, wovon zwei ein Selenocystein aufweisen
und konstitutiv exprimiert werden. Die Induktion der
Transkription der selenfreien Isoenzyme erfolgt dagegen bei
Selenmangel. In Expressionsanalysen zeigte sich, dass 5 weitere
Proteine ebenfalls nur unter Selenlimitierung synthetisiert
werden. Von zweien wurde jeweils die N-terminale Peptidsequenz
und von einem zusÀtzlich interne Peptidsequenzen bestimmt. In
der vorliegenden Arbeit wurde zunÀchst das Gen eines dieser
Proteine identifiziert. In einer Datenbanksuche stellte sich
dann heraus, dass es SequenzidentitÀten mit Corrinoid-Proteinen
aus Methanosarcina aufwies. Es wurde als SdmA bezeichnet (fĂŒr
Dimethylselenid Demethylierung). Das Gen sdmA liegt zusammen
mit sdmB und sdmC auf einem gemeinsamen polycistronischen
Messenger, der nur bei Selenmangel nachweisbar war. SdmB und
SdmC haben gemeinsame Sequenzmotive mit Methyltransferasen, die
in einigen Methanoarchaeen an der methylotrophen Methanogenese
beteiligt sind. Dabei ĂŒbertragen diese die Methylgruppe von
Corrinoid-Proteinen auf den Akzeptor Coenzym M. Die
Methylgruppe stammt dabei beispielsweise aus methylierten
Aminen bzw. Thiolen oder aus Methanol. Normalerweise werden von
M. voltae fĂŒr die Methanogenese nur Formiat oder H2/CO2
erschlossen, so bestÀtigte sich die Vermutung nicht, dass bei
Selenmangel SdmA, SdmB und SdmC die ErschlieĂung der oben
genannten methylierten Substrate erlauben könnten. Versetzt man
das Selenmangelmedium jedoch mit DMSe, dann fĂŒhrt dies zur
Repression des Promotors der Gene einer selenfreien
Hydrogenase, der normalerweise nur unter Selenlimitierung aktiv
wĂ€re. Eine Deletion von sdmA oder sdmC fĂŒhrte zur AktivitĂ€t des
Promotors trotz der Anwesenheit von DMSe. Der Austausch von
sdmB hatte dagegen keinen Effekt. Zudem waren die
Wachstumsraten der Mutanten delta sdmA und delta sdmB im
Vergleich zum Wildtyp trotz DMSe-Zugabe reduziert. In M. voltae
scheint es daher zwei verschiedene Anpassungsmechanismen an
Selenmangel zu geben. Zum einen werden unter Selenlimitierung
die selenfreien Isoenzyme der selenhaltigen Hydrogenasen
exprimiert und zum anderen lÀsst sich unter diesen Bedingungen
ein alternatives Selensubstrat, wie das DMSe, von M. voltae zur
Biosynthese der Selenoproteine erschlieĂen. Daran ist
vermutlich das Corrinoid-Proteine SdmA und die
Methyltransferase SdmC beteiligt
- âŠ