Vector Spring 2017

Vector is the student engineering magazine on campus. Published by the Student Engineering Council, Vector is completely written, managed, and designed by students for students. With issues dating back to 1971, the magazine has a long-standing tradition of serving as the voice for engineering students at The University of Texas at Austin. The Vector staff publishes two issues per semester. For more information regarding the Vector magazine, please contact us at vector@ sec.engr.utexas.eduCockrell School of EngineeringCockrell School of Engineerin

An integrated optical platform for micromanipulation of cells and tissue in live animals

Thesis (Ph.D.)--Boston UniversityThe hematopoietic stem cell niche is a specialized bone marrow (BM) microenvironment where blood-forming cells reside. Interactions between these rare cells and their niche need to be studied at the single-cell level. While live animal cell tracking with optical microscopy has proven useful for this purpose, a more thorough characterization requires novel approaches. This can be accomplished by using an integrated optical platform for cell and tissue manipulations (cell transplantation and extraction) in the skull bone of live mice. The platform integrates a non-damaging laser ablation microbeam for bone removal and tissue cutting, optical tweezers for single cell trapping, and a video-rate scanning microscope. For single cell delivery, a narrow channel is ablated through bone under imaging guidance. Cells are then transferred from a micropipette into an optical trap, which brings cells into the BM through the channel. The survival and proliferation of implanted cells can be tracked in vivo by imaging. For cell extraction after laser bone thinning, different approaches can be implemented and three of them are presented

Contest-Driven Soft-Robotics Boost: The RoboSoft Grand Challenge

This paper reports the design process, the implementation and the results of a novel robotic contest addressing soft robots, named RoboSoft Grand Challenge. Application-oriented tasks were proposed in three different scenarios where soft robotics is particularly lively: manipulation, terrestrial and underwater locomotion. Starting from about sixty expressions of interest submitted by international teams distributed across the world, nineteen robots were eventually selected to participate in the challenge in two of the initially proposed scenarios, i.e. manipulation and terrestrial locomotion. Results highlight both the effectiveness and limitations of state of the art soft robots with respect to the selected tasks. The paper will also focus on some of the advantages and disadvantages of contests as technology-steering mechanisms, including what we called "reductionist design", a phenomenon in which simplistic solutions are devised to purposely tackle the proposed tasks, possibly hindering more general and desired technological advancements

Design for Social Sustainability in Digital Fabrication for Development in the Global South

Context: The demand for humanitarian and development aid has risen to an unprecedented level. With an urgent need for new solutions, the aid sector has started turning to digital fabrication (3D printing, laser cutting and computer numerical control (CNC) milling). Collectively, these initiatives are referred to as Digital Fabrication for Development (DF4D). It is commonly believed that DF4D can support more low-cost, appropriate and localised forms of production in the Global South. Problem: Despite rhetoric about the transformative potential of DF4D, there is concern that technology projects in the aid sector have historically failed to create lasting impact. It is put forward that social sustainability is currently lacking and that this is limiting the success of DF4D. Despite recognition that social sustainability is the foundation for sustainable development, it is a challenging concept that is often neglected in mainstream sustainability research. In addition, the role of design in promoting social sustainability has not been well understood. Until this problem is addressed, it is believed that DF4D will not succeed in creating the social impact it desires. Research aim: To investigate how design can promote social sustainability in DF4D. Methodology: This thesis follows a pragmatic research paradigm. First, an exploratory study is conducted with fourteen case studies to validate that social sustainability is currently lacking in DF4D. Building on these findings, the main study is conducted with three case studies: a 3D printed otoscope in Nepal; a digitally fabricated prosthesis in India; and, a digital fabricated suction pump machine in Kenya. The main study diverges in two directions, with the first part focusing on an analytical approach and the second part taking a critical systems approach. In the analytical approach, thematic coding of case study data is used to identify the key principles of Design for Social Sustainability in DF4D. In the critical systems approach, Actor-Network Theory is used to investigate the networks of DF4D projects. Results: The analytical approach results in a normative framework to support Design for Social Sustainability in DF4D. It offers practical guidelines that are relevant in project planning and evaluation. The framework highlights the need for radical, systems-focused solutions. It reveals that design can trigger social sustainability at product, process and paradigm levels. The critical systems approach explores an interpretative version of Design for Social Sustainability. It supports the development of an initial toolkit that allows actors to collaboratively map their own networks during ongoing projects. Network analysis of the case studies clarifies the linkage between participation and Design for Social Sustainability. Reciprocity is highlighted as a key network metric that reveals (in)equitable relationships. The results of the analytical and critical systems approaches are compared to identify their complementary insights. It is put forward that Design for Social Sustainability in DF4D demands several shifts in practice from: products to capabilities; exogenous to endogenous development; passive to active actors; quick fixes to open-ended solutions; and, one-off projects to scalable interventions. It is argued that Design for Social Sustainability also has the potential to shape sustainability transitions beyond the project level. Theoretical implications: Synthesis of fragmented knowledge on Design for Social Sustainability and identification of its key principles in the DF4D context. Practical implications: The development of a practical framework and an initial toolkit that can support practitioners in DF4D to develop more socially sustainable solutions. Methodological implications: Explanation of how and why analytical and critical systems approaches can provide complementary insights for exploring complex phenomena.This research was supported by the EPSRC Doctoral Training Programme, grant number EP/L504920/

Form and function of the craniomandibular complex in subterranean rodents

Rodents are the most speciose mammalian order and are represented in arboreal, semiaquatic, subterranean and terrestrial niches. To flourish in such environments, rodents must exhibit morphological traits that can reflect functions that are needed to survive. This thesis focuses on the functional morphology of digging subterranean rodents and in particular, African mole-rats (Bathyergidae). Species dependent, subterranean rodents dig using a number of different methods. This thesis concentrates on the morphological differences in the craniomandibular complex in scratch digging and chisel-tooth digging subterranean rodents. Scratch digging rodents use only their claws to remove softer soil whilst their chisel-tooth digging counterparts use their incisors in concert with their powerful masticatory muscles to remove harder soils.Chapter two looks at morphological traits associated with bite force and gape in African mole-rats (Bathyergidae). The study shows that chisel-tooth digging rodents have morphological traits that are associated with a larger bite force at wider gapes, which is probably achieved by having a temporalis with a greater mechanical advantage.Chapter three examines a selection of chisel-tooth digging, scratch digging and terrestrial rodents. It shows that the upper incisors of chisel-tooth digging rodents have a larger radius of curvature. Also, it shows that chisel-tooth digging rodent cranial shape converges in morphospace and covaries with the upper incisors, although these results were not significant when phylogeny was accounted for.Chapter four shows that, using finite element analysis, the cranium of a chisel-tooth digging mole-rat can create larger bite forces at wider gapes, compared to a scratch digging mole-rat. Using a novel method of combining geometric morphometrics with finite element analysis, this study also shows that the cranium of the chisel-tooth digging rodent deforms less, making it more efficient at performing chisel-tooth digging tasks.Overall, this thesis shows that the craniomandibular form of subterranean rodents can be strongly influenced by function. The digging method used by a subterranean rodent is therefore important to how they have evolved.[Thesis also includes article published in:Biological journal of the Linnean Societyhttp://onlinelibrary.wiley.com/doi/10.1111/bij.12691/fullDOI: 10.1111/bij.12691

CONSTRAINTS OF THE IMAGINATION: HOW PHENOTYPES ARE SHAPED THROUGH GENETICS, THE ENVIRONMENT, AND DEVELOPMENT

Phenotypic constraints are ubiquitous throughout nature, being found throughout all stages of life and at multiple different biological levels including cellular, genetic, environmental, behavioral, evolutionary, and developmental. These constraints have shaped, not only the natural world, but the way that we perceive what is possible, or impossible, an observation made clear by François Jacob in his 1977 paper “Evolution and Tinkering”. This is reflected in the literature, repeatedly, by the regular occurrence of densely packed visualization of phenotypic space that seemingly always have large areas that go unoccupied. Despite constrained regions of space being observable across countless taxa, identifying the mechanisms of those constraints remains elusive. Given that constraints are widespread and have influenced how evolution may work, my aim was to identify mechanisms of constraint throughout multiple biological levels. Chapter one is divided into two parts, sections A and B, but largely focuses on how constraints are influenced by genetics. For this, we investigated crocc2, a protein that encodes for a structural component of the ciliary rootlet which in turn plays a major role as a mechanosensory for nearly all cells. We found dysfunctional crocc2 resulted in both dysmorphic bone development and a decrease in the plastic response potential of zebrafish (section A), as well as altered developmental trajectories in juvenile morphology, presumably due to alterations in cellular polarity and inadequate extracellular communication. Importantly, all results from this chapter point toward crocc2 play a canalizing role in the production of phenotypes at multiple life-history stages. Chapter 2 takes a different approach into understanding constrains by looking at broad ecological alterations and how those alterations may alter morphology of resident taxa. Here, we utilized the heavily altered habitat of the Tocantins River in the Amazon and the existing museum collections to evaluate how select representatives of the cichlid community had responded to such change. We found significant changes in contemporary morphology across all included cichlid species compared to their historical counterparts. These data show that alterations to the environment have resulted in changes to the local resident species, and possibly an alteration to their future evolutionary trajectories. Among the species included, one was found to have the most substantial morphological changes, which is what we followed up in the next chapter. Chapter 3 dug into the morphological changes of Satanoperca, a Geophagine cichlid with a unique feeding mechanism known as winnowing. Winnowing is a poorly understood mechanical process involving substrate manipulation. Given that anthropogenic alterations to local hydrology oft result in changes to the benthic sediment composition, we wanted to know if differing substrates was enough to induce a plastic response in winnowing fishes, and if so which traits were effected. We found significant differences across our experimental populations in both shape and disparity and present evidence in support of wide-spread integration across craniofacial traits. In addition, these data suggest that the novel anatomical structure, the epibranchial lobe, is more modular than other craniofacial traits involved in the winnowing process. Chapters 4 and 5 utilize a unique lineage of fishes, the Bramidae, to understand how developmental and evolutionary constraints are broken to produce morphological novelties. We used a combination of DNA sequences from GenBank and numerous museum specimens to illuminate constraints and determine how constraints are broken to produce complex phenotypic novelties. In Chapter 4, we found that the fanfishes had experienced greater rates of morphological evolution than other members of the Bramidae family, resulting in their occupation of an entirely novel region of phenotypic space. In Chapter 5, we elaborated on this by investigating the developmental processes involved in producing an extreme morphological novelty. The data presented in Chapter 5 provide evidence suggesting that the fanfishes have broken various constraints, resulting in prominent anatomical and morphological changes to accommodate their novel phenotype. In all, my dissertation provides examples of how constraints have shaped the variability that we see throughout life and shows examples of how constraints can be identified, what happens when they are broken, and how they work to control the pace and trajectory of evolutionary processes

The ecomorphology of facultative bipedality in Lepidosauria: implications for the evolution of reptilian bipedality

Bipedality is a distinctive locomotor characteristic of some of the most noteworthy animals of all time, including dinosaurs and humans. However, the evolution of a bipedal locomotor mode is poorly understood in reptiles. It has been repeatedly hypothesised that a facultative locomotor mode, where an animal moves both bipedally and quadrupedally under different conditions, forms an intermediate stage in the evolution of obligate bipedality. I demonstrate that the evidence supporting this hypothesis is lacking, recovering facultative bipedality as an intermediate stage only once in multiple independent evolutions of bipedality, under two different topologies. In order to better understand facultative bipedality and the associated anatomies, I performed multiple studies into the ecomorphology and evolution of this behaviour in a modern clade: Lepidosauria. Linear morphometric studies accounting for variation in body size indicate that forelimb segment lengths across locomotor modes do not differ for lepidosaurs of the same size, but that distal hindlimbs segments differ greatly, contrasting with historical tropes. Using 3D landmark-based geometric morphometrics, I demonstrate that arboreal and facultatively bipedal species share many characteristics in the bony elements of the pelvis, including a straight-to-concave iliac blade and large ischial base. These shared anatomies are functionally qualified based on anatomical studies of lepidosaur pelvic girdle myology, and indicate a similarity in mechanical demands of both arboreality and facultative bipedality. Finally, I tested for the correlated evolution of facultative bipedality with substrate preference in a derived clade of squamates: Episquamata. Findings suggest that there is no correlation between substrate and a facultative locomotor mode, instead indicating that facultative bipedality is an exaptation of anatomies associated with vertically diverse environments. This echoes the evolution facultative bipedality in hominin, macropods and rodents, and is distinct from any current hypotheses concerning the evolution of archosaurian bipedality