THERMOMECHANICAL MECHANISMS THAT CAUSE ADHESION OF ALUMINUM HIGH PRESSURE DIE CASTINGS TO THE DIE

In high pressure die casting (HPDC) of aluminum, cast material adhering to die is a significant defect. Adhesion occurs in two primary ways. The casting may stick preventing its removal from the die. Aluminum can also adhere to the die and buildup in local areas on the die surface with additional casting cycles. This second form of adhesion is called soldering. Lubricant is the best technology to control all forms of adhesion, but it comes at the cost of casting porosity, blisters, reduced die life, and increased die casting machine wear. New strategies to prevent adhesion are desired to eliminate the downsides of spray lubricants. Thermodynamically, there is a drive to form intermetallic phases between the aluminum casting and steel die. The kinetically controlled formation of these phases has been understood as the primary mechanism which causes sticking and soldering. Assuming this mechanism, adhesion should be eliminated by coating the die surface with a non-reactive material, but laboratory and industrial experiments show that this approach is partially effective. Also, kinetics based predictions cannot identify the areas where adhesion is most severe. Additional mechanisms are needed to further predict and reduce these defects. Friction is such a mechanism, and it has been overlooked as a significant cause of sticking and soldering in HPDC. Sticking results from the thermal contraction of the casting onto the die. This creates a friction force that resists ejection and may be larger than the ejection force capability of the die casting machine. Soldering is a special case where the local shear stress due to friction exceeds the local shear strength of the casting. This typically happens at high temperatures and can be predicted by the ratio of the local ejection shear stress and temperature dependent shear strength. Four aspects of HPDC adhesion were investigated to support this friction mechanism. First, the accepted theory of a kinetically controlled approach to the thermodynamic equilibrium does not adequately predict sticking and soldering. Next, the decrease in sticking force with increasing draft angle is predicted by a friction model. Third, soldering is shown to occur when the shear stress at ejection exceeds the strength of the casting via hot ejection test and computer models of industrial castings. Finally, the friction approach is applied to a range of casting conditions and alloys with discussion of optimization opportunities

AWARE: Analyzing the Impact of an Anti-Human Trafficking Advocacy Curriculum using Sixth Grade Students in Colorado

Human trafficking is an international problem that penetrates every society on the globe. Trafficking in children for the purposes of commercial sexual exploitation, forced labor, and domestic servitude occurs in every state of the United States. Education is key in preventing human trafficking and American students lack proper knowledge of the issue. This study seeks to bridge this shortcoming through the creation and implementation of a holistic anti-trafficking advocacy curriculum that not only informs and motivates students and educators toward advocacy, but also meets Colorado state academic standards. Case studies using sixth grade students in Denver show the impact that such a curriculum has, not only on knowledge gained, but student empowerment and civic responsibility through advocacy. The author analyzes the impact of the Aware Curriculum through formative and summative assessments, classroom observation, and diagnostic written assessments to gauge knowledge, comprehension of key concepts, and student thought processes about anti-trafficking advocacy

The Shadow Space of Allegorical Machines: Situating Locative Media

This dissertation utilizes a media archaeological approach to the analysis of locative media, which are technologies that organize an experience of spatial orientation. For instance, a user can use a mobile phone to connect to a cellular network and generate a visualization of the material space in which he or she is positioned with annotated or interactive information on the screen. My critical approach to locative media is influenced by a historical constellation of orientation technologies, their contributions to the social imaginations of space, and the resulting experiences and expectations that are negotiated by the material, symbolic, and ideal. Four case studies on the astrolabe, magnetic compass, divining rod, and digital locative media make up a broader historical arrangement of which, I argue, digital locative media are the latest manifestation. Like other media technologies such as radio or television, these spatial technologies offer a window onto another world while also offering (other)spaces of symbolic and cultural codes that are layered over material space. The ability to reveal these otherspaces is associated with the recurring transcendent logic of locative media as individuals are encouraged to unveil the real behind the apparent in order to become united with a hybrid (and enchanted) ecology of the virtual and real. My locative media archaeology involves a theorization of allegorical machines, which is a term I use to analyze the interfaced interpretation of a shadow (imagined or informational) otherspace in relation to a porous correspondence between subject and space. This theorization is an interrogation of how engineers, technological promoters, and users position allegorical machines as making the supersensible sensible through an interface with the sublime. In other words, locative media are technological attempts to make the vague intelligible by bringing what lies outside the realm of physical experience into contact with the senses. Transcending to otherspaces such as the electromagnetic spectrum or the digital network involves an inherent metaphysics of the interface, which as liaisons between bodies and spaces generate animations such as the one that is the focus of this dissertation: the sublime desire or fear of unveiling the unknown space beyond space.Doctor of Philosoph

Generation of continuous variable squeezing and entanglement of trapped ions in time-varying potentials

We investigate the generation of squeezing and entanglement for the motional degrees of freedom of ions in linear traps, confined by time-varying and oscillating potentials, comprised of an DC and an AC component. We show that high degrees of squeezing and entanglement can be obtained by controlling either the DC or the AC trapping component (or both), and by exploiting transient dynamics in regions where the ions' motion is unstable, without any added optical control. Furthermore, we investigate the time-scales over which the potentials should be switched in order for the manipulations to be most effective.Comment: 10 pages, submitted to Quantum Information Processing (special issue on Quantum Decoherence and Entanglement

Linking human behaviours and malaria vector biting risk in south-eastern Tanzania

To accelerate malaria elimination in areas where core interventions such as insecticide-treated nets (ITNs) are already widely used, it is crucial to consider additional factors associated with persistent transmission. Qualitative data on human behaviours and perceptions regarding malaria risk was triangulated with quantitative data on Anopheles mosquito bites occurring indoors and outdoors in south-eastern Tanzania communities where ITNS are already used but lower level malaria transmission persists. Each night (18:00h-07:00h), trained residents recorded human activities indoors, in peri-domestic outdoor areas, and in communal gatherings. Host-seeking mosquitoes were repeatedly collected indoors and outdoors hourly, using miniaturized exposure-free double net traps (DN-Mini) occupied by volunteers. In-depth interviews were conducted with household representatives to explore perceptions on persistent malaria and its control. Higher proportions of people stayed outdoors than indoors in early-evening and early-morning hours, resulting in higher exposures outdoors than indoors during these times. However, exposure during late-night hours (22:00h-05:00h) occurred mostly indoors. Some of the popular activities that kept people outdoors included cooking, eating, relaxing and playing. All households had at least one bed net, and 83.9% of people had access to ITNs. Average ITN use was 96.3%, preventing most indoor exposure. Participants recorgnized the importance of ITNs but also noted that the nets were not perfect. No complementary interventions were reported being used widely. Most people believed transmission happens after midnight. We conclude that insecticide-treated nets, where properly used, can still prevent most indoor exposures, but significant risk continues unabated before bedtime, outdoors and at communal gatherings. Such exposure is greatest for rural and low-income households. There is therefore an urgent need for complementary interventions, particularly those targeting outdoor-biting and are applicable for all people including the marginalised populations such as migratory farmers and fishermen. Besides, the differences in community understanding of ongoing transmission, and feedback on imperfections of ITNs should be considered when updating malaria-related communication and interventions

Reduced evolutionary rate in reemerged Ebola virus transmission chains

On 29 June 2015, Liberia’s respite from Ebola virus disease (EVD) was interrupted for the second time by a renewed outbreak (“flare-up”) of seven confirmed cases. We demonstrate that, similar to the March 2015 flare-up associated with sexual transmission, this new flare-up was a reemergence of a Liberian transmission chain originating from a persistently infected source rather than a reintroduction from a reservoir or a neighboring country with active transmission. Although distinct, Ebola virus (EBOV) genomes from both flare-ups exhibit significantly low genetic divergence, indicating a reduced rate of EBOV evolution during persistent infection. Using this rate of change as a signature, we identified two additional EVD clusters that possibly arose from persistently infected sources. These findings highlight the risk of EVD flare-ups even after an outbreak is declared over

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Proceedings of the 3rd Biennial Conference of the Society for Implementation Research Collaboration (SIRC) 2015: advancing efficient methodologies through community partnerships and team science

It is well documented that the majority of adults, children and families in need of evidence-based behavioral health interventionsi do not receive them [1, 2] and that few robust empirically supported methods for implementing evidence-based practices (EBPs) exist. The Society for Implementation Research Collaboration (SIRC) represents a burgeoning effort to advance the innovation and rigor of implementation research and is uniquely focused on bringing together researchers and stakeholders committed to evaluating the implementation of complex evidence-based behavioral health interventions. Through its diverse activities and membership, SIRC aims to foster the promise of implementation research to better serve the behavioral health needs of the population by identifying rigorous, relevant, and efficient strategies that successfully transfer scientific evidence to clinical knowledge for use in real world settings [3]. SIRC began as a National Institute of Mental Health (NIMH)-funded conference series in 2010 (previously titled the “Seattle Implementation Research Conference”; $150,000 USD for 3 conferences in 2011, 2013, and 2015) with the recognition that there were multiple researchers and stakeholdersi working in parallel on innovative implementation science projects in behavioral health, but that formal channels for communicating and collaborating with one another were relatively unavailable. There was a significant need for a forum within which implementation researchers and stakeholders could learn from one another, refine approaches to science and practice, and develop an implementation research agenda using common measures, methods, and research principles to improve both the frequency and quality with which behavioral health treatment implementation is evaluated. SIRC’s membership growth is a testament to this identified need with more than 1000 members from 2011 to the present.ii SIRC’s primary objectives are to: (1) foster communication and collaboration across diverse groups, including implementation researchers, intermediariesi, as well as community stakeholders (SIRC uses the term “EBP champions” for these groups) – and to do so across multiple career levels (e.g., students, early career faculty, established investigators); and (2) enhance and disseminate rigorous measures and methodologies for implementing EBPs and evaluating EBP implementation efforts. These objectives are well aligned with Glasgow and colleagues’ [4] five core tenets deemed critical for advancing implementation science: collaboration, efficiency and speed, rigor and relevance, improved capacity, and cumulative knowledge. SIRC advances these objectives and tenets through in-person conferences, which bring together multidisciplinary implementation researchers and those implementing evidence-based behavioral health interventions in the community to share their work and create professional connections and collaborations