852 research outputs found
Comparing Travel Time Estimates of Routing Applications in Vienna.
How are travel times displayed by different navigation apps? Do the way in which these work differ for
different modes of transportation? We found unexpected divergence in the way travel time is displayed
both between apps and within apps, when conducting testing on travel routing apps in Vienna. As a result,
this paper will provide a brief overview of how travel times are displayed by commonly used apps in
Vienna and how these differ. In conclusion, we will suggest different avenues for additional research based
on these findings and illustrate the challenges of user accountability associated with these apps
Bias in Geographic Information Systems: The Case of Google Maps
Users\u27 perception of geographic space depends heavily on geographic information systems (GIS). GIS are the most common way for users to estimate travel time, provide routing information and recommend appropriate forms of transportation. This article analyses how predictions made by Google Maps, one of the most popular GIS, influence users\u27 perceptions and travel choices. To analyze this influence, a pre-study in a classroom setting (n=36) as well as an online survey (n=521) were conducted. We study users intuitive perception of travel time, before using the Google Maps Mobile App as a \u27treatment\u27 to see how it influences their perceptions of travel time and choice of transportation type. We then contrast this original Google Maps treatment to a mock-up \u27warning label version\u27 of Google which informs users about biases in Google Maps and an \u27unbiased version\u27 of Google Maps based on ground truth data. Our analysis suggests that Google Maps systematically underestimates necessary car driving time, which has an impact on users\u27 choice of transportation
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Elastocapillarity: adhesion and large deformations of thin sheets
This thesis is concerned with the deformation and adhesion of thin elastic sheets that come into contact with an underlying substrate. The focus of this work is on the interplay between material and geometric properties of a system and how this interplay determines the equilibrium states of sheet and substrate, particularly in the regime of geometrically nonlinear deformations.
We first consider the form of an elastic sheet that is partially adhered to a rigid substrate, accounting for deflections with large slope: the Sticky Elastica. Starting from the classical Euler Elastica we provide numerical results for the profiles of such blisters and present asymptotic expressions that go beyond the previously known, linear, approximations. Our theoretical predictions are confirmed by desktop experiments and suggest a new method for the measurement of material properties for systems undergoing large deformations.
With the aim to gain better understanding of the initial appearance of blisters we next investigate the deformation of a thin elastic sheet floating on a liquid surface. We show that, after the appearance of initial wrinkles, the sheet delaminates from the liquid over a finite region at a critical compression, forming a delamination blister. We determine the initial blister size and the evolution of blister size with continuing compression before verifying our theoretical results with experiments at a macroscopic scale.
We next study theoretically the deposition of thin sheets onto a grooved substrate, in the context of graphene adhesion. We develop a model to understand the equilibrium of the sheet allowing for partial conformation of sheet to substrate. This model gives phys- ical insight into recent observations of ‘snap-through’ from flat to conforming states and emphasises the crucial role of substrate shape in determining the nature of this transition.
We finally present a theoretical investigation of stiction in nanoscale electromechanical contact switches. Our model captures the elastic bending of the switch in response to both electrostatic and van der Waals forces and accounts for geometrically nonlinear deflections. We solve the resulting equations numerically to study how a cantilever beam adheres to a fixed bottom electrode: transitions between free, pinned and clamped states are shown to be discontinuous and to exhibit significant hysteresis. The implications for nanoscale switch design are discussed
A Journey, not a Destination—A Synthesized Process of Digital Transformation
Digital transformation (DT) continues to shake up firms and societies at large. Despite a growing number of studies covering a wide array of aspects of DT’s content, evidence of how DT unfolds in firms remains fragmented. Thus far, the literature has provided punctual insights into firms’ DT processes through single and multiple case studies. However, we lack a holistic understanding of the DT process. Adopting a qualitative meta-synthesis, we analyze 64 cases to inductively develop a DT process model depicting six phases (i.e., initiating, preparing, mobilizing, implementing, disseminating, and iterating). The process evolves on two levels—one rather sequential and one non-linear. We contribute to literature by introducing a synthesized process model tailored to DT’s complex nature. Besides, our model provides practitioners with a frame for assessing the progress of their DT journey and outlining a roadmap for their digital endeavor
Response of Lactobacillus casei BL23 to phenolic compounds
2 tables, 2 figures.-- Article first published online: 17 OCT 2011.-- The definitive version is available at www3.interscience.wiley.comAims: To determine the inhibitory effect of phenolic compounds on Lactobacillus casei BL23, the role of two component signal transduction systems (TCS) and the response of Lact. casei BL23 to p-coumaric acid.
Methods and Results: Growth of Lact. casei BL23 and 17 derivative strains defective in each TCS harboured by this strain in the presence of p-coumaric acid, ferulic acid, caffeic acid or methyl gallate was monitored. Furthermore, changes in the protein content of Lact. casei BL23 when exposed to p-coumaric acid were evaluated by 2D-SDS-PAGE. Eleven proteins differentially expressed in the presence of p-coumaric acid were detected. Six of them could be identified: ClpP and HtrA, involved in protein turnover and folding, acetyl-CoA carboxylase, involved in lipid metabolism, and an arginyl-tRNA synthetase were more abundant, whereas PurL and PurN, involved in purine biosynthesis, were less abundant.
Conclusions: No significant differences were observed between the parental strain and the TCS-defective mutants. p-Coumaric acid elicited a response against membrane and cytoplasmic damages.
Significance and Impact of the Study: The inhibitory effect of phenolic compounds on Lact. casei BL23 has been determined. For the first time, cytoplasmic proteins presumably involved in the response of Lact. casei BL23 against p-coumaric acid have been identified.This work was financed by AGL2010-15679 and Consolider Fun-C-Food CSD2007-00063 funds from the Spanish Ministry of Science and Innovation (MICINN) and FEDER. J.M. Landete enjoyed a postdoctoral contract of the programme ‘Juan de la Cierva’ (MICINN).Peer reviewe
Can gadolinium contrast agents be replaced with saline for direct MR arthrography of the hip? A pilot study with arthroscopic comparison.
OBJECTIVE
To compare image quality and diagnostic performance of preoperative direct hip magnetic resonance arthrography (MRA) performed with gadolinium contrast agent and saline solution.
METHODS
IRB-approved retrospective study of 140 age and sex-matched symptomatic patients with femoroacetabular impingement, who either underwent intra-articular injection of 15-20 mL gadopentetate dimeglumine (GBCA), 2.0 mmol/L ("GBCA-MRA" group, n = 70), or 0.9% saline solution ("Saline-MRA" group, n = 70) for preoperative hip MRA and subsequent hip arthroscopy. 1.5 T hip MRA was performed including leg traction. Two readers assessed image quality using a 5-point Likert scale (1-5, excellent-poor), labrum and femoroacetabular cartilage lesions. Arthroscopic diagnosis was used to calculate diagnostic accuracy which was compared between groups with Fisher's exact tests. Image quality was compared with the Mann-Whitney U tests.
RESULTS
Mean age was 33 years ± 9, 21% female patients. Image quality was excellent (GBCA-MRA mean range, 1.1-1.3 vs 1.1-1.2 points for Saline-MRA) and not different between groups (all p > 0.05) except for image contrast which was lower for Saline-MRA group (GBCA-MRA 1.1 ± 0.4 vs Saline-MRA 1.8 ± 0.5; p 0.999/p = 0.904) and acetabular (GBCA-MRA 86%/ 83% versus Saline-MRA 89%/87%; p = 0.902/p = 0.901) and femoral cartilage lesions (GBCA-MRA 97%/ 99% versus Saline-MRA 97%/97%; both p > 0.999).
CONCLUSION
Diagnostic accuracy and image quality of Saline-MRA and GBCA-MRA is high in assessing chondrolabral lesions underlining the potential role of non-gadolinium-based hip MRA.
KEY POINTS
• Image quality of Saline-MRA and GBCA-MRA was excellent for labrum, acetabular and femoral cartilage, ligamentum teres, and the capsule (all p > 0.18). • The overall image contrast was lower for Saline-MRA (Saline-MRA 1.8 ± 0.5 vs. GBCA-MRA 1.1 ± 0.4; p 0.999), acetabular cartilage damage (89% vs. 86%; p = 0.902), femoral cartilage damage (97% vs. 97%; p > 0.999), and extensive cartilage damage (97% vs. 93%; p = 0.904)
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