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Frequency Reduction and Attenuation of the Tire Air Cavity Mode due to a Porous Lining
Get PDFThe tire air cavity mode is known to be a significant source of vehicle structure-borne road noise near 200 Hz. A porous lining placed on the inner surface of a tire is an effective countermeasure to attenuate that resonance. The two noticeable effects of such a lining are the reduction in the cavity resonance frequency and the attenuation of the air cavity mode. In this paper, through both theoretical and numerical analysis, the mechanisms underlyiing the effects of a porous lining were studied. A two-dimensional duct-shaped theoretical model and a torus-shaped numerical model were created to investigate the lined tire in conjunction with the Johnson-Champoux-Allard model describing the viscous and thermal dissipative effects of the porous material. Design parameters of the porous lining were varied to study their impact and optimal ranges of the design parameters were identified. Finally, in an experimental analysis, the sound attenuation and the frequency drop were observed in measurements of force, acceleration, and sound pressure. In conclusion, it was demonstrated that the suggested theoretical and numerical models successfully predict the effects of porous linings and that the frequency reduction results from the decreased sound speed within the tire owing to the presence of the liner
CAN DIGITAL MARKETING ON INSTAGRAM HELP TO PROMOTE SUSTAINABLE TRAVEL? Abstract
Get PDFThe contribution of digitalization and digital platforms to tourism sustainability is a timely topic. In this research we analyze if a digital platform such as Instagram could contribute and be used as a tool to promote sustainability by destinations and by travelers. To this aim, we implement a methodology comprised of four steps: identifying the most recognized sustainable destinations in the world (i.e. Slovenia, New Zealand and Costa Rica), downloading and analyzing the last posts from the official accounts of the DMOs of these destinations, identifying the most frequently used hashtags related to sustainable tourism (#ecoturismo, #ecotourism, #sustainabletravel, #ecotravel and #sustainabletourism), and downloading and analyzing 500 posts from these accounts. Our results are mixed, and show some opportunities but also significant challenges and puzzling outcomes. In general, there does not seem to be a consistent use of sustainability concepts in the publications analyzed
Young Indigenous Entrepreneurs- Supporting Changemakers Through Entrepreneurship and Advocacy of Indigenous Issues
Get PDFIndigenous youth are reclaiming their language, customs and land. They are at the forefront of Canada’s fastest-growing population, yet continue to face barriers in health, education and justice systems. Indigenous tourism often exploits Indigenous communities. However, self-driven Indigenous tourism is an opportunity for Indigenous communities to strengthen their culture and economy. Many Indigenous youth aspire to start businesses. Their products are often sold not just nationally, but also to international customers. Hence, a program that provides financial literacy courses and personalized business advice can support young Indigenous entrepreneurs. Based on the experience of a young Indigenous entrepreneur who sells beadwork through social media, this case explores best business practices and strategies for success through accounting concepts. In this case, two post-secondary student consultants are tasked with supporting a young Indigenous entrepreneur by developing a business model, in an effort to contribute to Alberta’s Indigenous tourism. With the development of the United Nations Declaration on the Rights of Indigenous People, Indigenous rights have become a prominent global issue and this case is relevant in the context of Indigenous socio-economic development
Battle Tactics: Ralstonia Solanacearum K60 Type III Effector Impacts Plant Cytoskeleton
No full textUnlike mammals, plants lack an adaptive immune system and rely solely on innate immunity to recognize microbial pathogens. To further defend against pathogens, plants evolved two layers of immune systems to recognize and fend off pathogens. The first branch, PAMPs-Triggered Immunity (PTI), relies on cell-surface localized and intracellular receptors (pathogen recognition receptors; PRRs) to recognize PAMPs (pathogenic associated molecular patterns). This recognition activates several immune outputs, such as calcium influx, reactive oxygen species (ROS), and callose deposition. In a second layer, plants can launch a more specific and robust immune response called ETI (Effector Triggered Immunity).To counter plant immunity, bacterial pathogens deliver virulence proteins, known as T3Es (type III effectors), into plant cells through a needle-like apparatus called the type III secretion system (T3SS). To perform their functions, T3E localizes to different subcellular compartments to affect host cell functionality; therefore, knowing T3E localization is informative for developing hypotheses about effectors and their potential targets. Thus, to gain insight into the function of Ralstonia T3Es, we examined the in planta localization of 19 T3Es from Ralstonia species. This localization screening revealed a novel T3E that localizes to the host cytoskeleton.The plant cytoskeleton is commonly considered a vital component of cell growth and development; however, it also plays a critical role in plant immunity. During plant immunity, the cytoskeleton orchestrates rapid and precise immune-associated processes. For instance, the cytoskeleton mobilizes and orients the movement of organelles, proteins, and chemical signaling. Currently, only eight documented bacterial T3Es impact the cytoskeleton: four from Pseudomonas syringae (HopW1, HopG1, HopZa1, HopE1), three from Xanthomonas spp. (XopR, AvrBsT, and XopL) and one from Acidovorax citrulli (AopW1).A novel T3E, called RipU, interacts with the cytoskeleton. Data has shown that RipU co-localizes with cytoskeletal markers in tobacco leaves. Ectopic expression of RipU can suppress PTI responses like ROS bursts or seedling growth inhibition. Tomato plants inoculated with Rs K60 lacking RipU showed less wilting and root colonization, suggesting that RipU plays a role in pathogenesis and virulence. Furthermore, inducible expression of RipU in Arabidopsis dramatically alters plant development. These plants have wavy roots, branching root hairs, and underdeveloped true leaves. Our results suggest that by targeting the cytoskeleton, RipU contributes to Rs K60s pathogenicity and virulence
Experimental Approaches to Advance Hellbender Headstarting
No full textThe Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) is a fully aquatic salamander found throughout the eastern United States. Hellbenders require cool, fast-moving rivers and streams with flat rock substrates for shelter. Due to habitat degradation and anthropogenic changes across landscapes, Hellbenders have required intervention programs to reduce extirpation and extinction risks. Over 5000 Hellbenders are found in captive-rearing and breeding programs throughout 15 different states. However, captive-rearing standards vary from facility to facility.Currently, Hellbender captive-rearing programs are based on established zoo guidelines that recommend rearing in traditional glass aquaria until they reach releasable mass (~60 g) at approximately three years of age. To achieve releasable size, the guidelines provide density and food availability requirements based on the amount of available floor space of the enclosure. Unfortunately, because these guidelines lack empirical data, it is unclear whether these recommendations are optimizing captive-rearing efforts for Hellbenders and, therefore, optimizing conservation potential.There is an overall lack of available information on housing conditions and requirements for Hellbenders outside of intraspecies aggression or cannibalism. Because many facilities use different types of housing conditions, there is substantial variation in the time needed to achieve the release size threshold. Our objectives were to: 1) understand how different raceway sizes impact growth rates of juvenile Hellbenders and 2) understand the effects of density and food availability on larval Hellbender growth. Both of these goals will allow us to develop optimal housing and husbandry standards and optimizing conservation potential within rearing facilities. Our study will build on our current knowledge of Hellbender captive-rearing techniques and provide empirical data to create optimal rearing standards nationwide
An Analysis of African American Undergraduate Students’ and Mentors’ Perceptions of the Impact of their Mentorship Community on College Persistence at a Predominantly White Institution
No full textMentorship has served as an effective strategy in helping African American college students persist at predominantly White institutions of higher education (Sinanan, 2016). African American students have reported finding these campus environments to be unwelcoming, even racist. These environmental challenges along with the challenges of unfamiliar academic terrain merge to form frequently formidable barriers to their satisfaction and success. The presence of African American mentors has helped African American students overcome the wide range of challenges they face on such campuses. This qualitative study analyzed the perceptions of African American mentors and mentees about the impact of mentorship on the college persistence of the mentees. The target mentorship community was situated at a private school in the Midwest. Semistructured interviews were used to solicit the experiential knowledge of participants about their lived experiences. The data was codified and thematically analyzed. Six themes emerged from participant responses including (1) targeted mentorship and modeling, (2) belonging, (3) connections (4) advocacy, (5) racism and anti-Blackness, and (6) persistence. These themes fortify the existing research affirming mentorship as an invaluable tool in helping African American undergraduates persist through degree completion. The assertions and recommendations at the conclusion of the study are purposed to assist scholar-activists, university staff, and students with improving the conditions in which African American students’ study and push toward persistence
The Pursuit of Effective Artificial Tactile Speech Communication: Improvements and Cognitive Characteristics of a Phonemic-Based Approach
No full textTactile speech communication allows individuals to understand speech by sensations transmitted through the sense of touch. Devices that enable tactile speech communication can be an effective means to transmit important messages when the visual and/or auditory systems are overloaded or impaired. This has applications in silent communication and for people with hearing and/or visual impairments. An effective artificial speech communication system must be learned in a reasonable time and be easily remembered. Moreover, it must transmit any word at suitable rates for speech communication. The pursuit of a system that fulfills these requirements is a complex task that requires work in different areas. This thesis presents advancements in four of them. First is the matter of encoding speech information. Here, a phonemic-based approach allowed participants to recognize of tactile phonemes, words, phrases and full sentences. Second is the issue of training users in the use of the system. To this end, this thesis investigated the phenomenon of incidental categorization of vibrotactile stimuli as the foundation of more natural methods to learn a tactile speech communication system. Third is the matter of the neural processing of the tactile speech information. Here, an exploration of the functional characteristics of the phonemic-based approach using EEG was conducted. Finally, there is the matter of implementing the system for consumer use. In this area, this work addresses practical considerations of delivering rich haptic effects with current wearable technologies. These are informative for the design of actuators used in tactile speech communication devices
On the Topology of Symmetric Semialgebraic Sets
No full textThis work strengthens and extends an algorithm for computing Betti numbers of symmetric semialgebraic sets developed by Basu and Riener in [11]. We first adapt a construction of Gabrielov and Vorobjov in [18] for replacing arbitrary definable sets by compact ones to the symmetric case. The original construction provided maps from the homotopy and homology groups of the replacement set to those of the original; we show that for sets symmetric relative to the action of some finite reflection group G, we may construct these maps to be equivariant. This modification to the construction for compact replacement allows us to extend Basu and Riener’s theorem on which submodules appear in the isotypic decomposition of each cohomology space to sets not necessarily closed and bounded. Furthermore, by utilizing this equivariant compact approximation, we may obtain a precise description of the aforementioned decomposition of each cohomology space, and not merely the final dimension of the space, from Basu and Riener’s algorithm.Though our equivariant compact replacement holds for G any finite reflection group, Basu and Riener’s results only consider the case of the action the of symmetric group, sometimes termed type A. As a first step towards generalizing Basu and Riener’s work, we examine the next major class of symmetry: the action of the group of signed permutations (known as type B). We focus our attention on Vandermonde varieties, a key object in Basu and Riener’s proofs. We show that the intersection of a type B Vandermonde variety with a fundamental region of type B symmetry is topologically regular. We also prove a result about the intersection of a type B Vandermonde variety with the walls of this fundamental region, leading to the elimination of factors in a different decomposition of the homology spaces
The Challenge of Misclassification Error in the European Union’s Deforestation Regulation
Get PDFThe European Union’s Regulation 2023/1115, which requires firms to undertake significant due diligence efforts to minimize the import of deforestation-linked commodities into the Union, relies heavily on cutting-edge geospatial technologies. While several studies of zero-deforestation supply chain efforts have pointed to the political and logistical challenges such initiatives face, there has been less consideration of the role that the measurement errors that are unavoidable in geospatial technologies might affect emerging zero-deforestation governance systems. Using information on misclassification error rates for forest areas from 20 recent validation studies of global land-cover datasets, I simulate the misclassification risks we might expect from a proposed global system designed to facilitate implementing the regulation. I argue that misclassification errors could pose problems for small operators, particularly in mosaic forest landscapes, as well as producers engaging in agroforestry. While some strategies could mitigate these risks, they are unlikely to be eliminated entirely, and their inevitability should be considered in implementing the Regulation
Inkjet-printed morphogenesis of tumor-stroma interface using bi-cellular bioinks of collagen-poly(N-isopropyl acrylamide-co-methyl methacrylate) mixture
Get PDFRecent advances in biomaterials and 3D printing/culture methods enable various tissue-engineered tumor models. However, it is still challenging to achieve native tumor-like characteristics due to lower cell density than native tissues and prolonged culture duration for maturation. Here, we report a new method to create tumoroids with a mechanically active tumor-stroma interface at extremely high cell density. This method, named “inkjet-printed morphogenesis” (iPM) of the tumor-stroma interface, is based on a hypothesis that cellular contractile force can significantly remodel the cell-laden polymer matrix to form densely-packed tissue-like constructs. Thus, differential cell-derived compaction of tumor cells and cancer-associated fibroblasts (CAFs) can be used to build a mechanically active tumor-stroma interface. In this methods, two kinds of bioinks are prepared, in which tumor cells and CAFs are suspended respectively in the mixture of collagen and poly (N-isopropyl acrylamide-co-methyl methacrylate) solution. These two cellular inks are inkjet-printed in multi-line or multi-layer patterns. As a result of cell-derived compaction, the resulting structure forms tumoroids with mechanically active tumor-stroma interface at extremely high cell density. We further test our working hypothesis that the morphogenesis can be controlled by manipulating the force balance between cellular contractile force and matrix stiffness. Furthermore, this new concept of “morphogenetic printing” is demonstrated to create more complex structures beyond current 3D bioprinting techniques