Designing the pressure-dependent shear modulus using tessellated granular metamaterials

Jammed packings of granular materials display complex mechanical response. For example, the ensemble-averaged shear modulus $\left\langle G \right\rangle$ increases as a power-law in pressure $p$ for static packings of soft spherical particles that can rearrange during compression. We seek to design granular materials with shear moduli that can either increase {\it or} decrease with pressure without particle rearrangements even in the large-system limit. To do this, we construct {\it tessellated} granular metamaterials by joining multiple particle-filled cells together. We focus on cells that contain a small number of bidisperse disks in two dimensions. We first study the mechanical properties of individual disk-filled cells with three types of boundaries: periodic boundary conditions (PBC), fixed-length walls (FXW), and flexible walls (FLW). Hypostatic jammed packings are found for cells with FLW, but not in cells with PBC and FXW, and they are stabilized by quartic modes of the dynamical matrix. The shear modulus of a single cell depends linearly on $p$. We find that the slope of the shear modulus with pressure, $\lambda_c < 0$ for all packings in single cells with PBC where the number of particles per cell $N \ge 6$. In contrast, single cells with FXW and FLW can possess $\lambda_c > 0$, as well as $\lambda_c < 0$, for $N \le 16$. We show that we can force the mechanical properties of multi-cell granular metamaterials to possess those of single cells by constraining the endpoints of the outer walls and enforcing an affine shear response. These studies demonstrate that tessellated granular metamaterials provide a novel platform for the design of soft materials with specified mechanical properties

Flight Deck Technologies to Enable NextGen Low Visibility Surface Operations

Many key capabilities are being identified to enable Next Generation Air Transportation System (NextGen), including the concept of Equivalent Visual Operations (EVO) . replicating the capacity and safety of today.s visual flight rules (VFR) in all-weather conditions. NASA is striving to develop the technologies and knowledge to enable EVO and to extend EVO towards a Better-Than-Visual operational concept. This operational concept envisions an .equivalent visual. paradigm where an electronic means provides sufficient visual references of the external world and other required flight references on flight deck displays that enable Visual Flight Rules (VFR)-like operational tempos while maintaining and improving safety of VFR while using VFR-like procedures in all-weather conditions. The Langley Research Center (LaRC) has recently completed preliminary research on flight deck technologies for low visibility surface operations. The work assessed the potential of enhanced vision and airport moving map displays to achieve equivalent levels of safety and performance to existing low visibility operational requirements. The work has the potential to better enable NextGen by perhaps providing an operational credit for conducting safe low visibility surface operations by use of the flight deck technologies

Potential Deaths Averted and Serious Adverse Events Incurred From Adoption of the SPRINT (Systolic Blood Pressure Intervention Trial) Intensive Blood Pressure Regimen in the United States: Projections From NHANES (National Health and Nutrition Examination Survey)

BACKGROUND: SPRINT (Systolic Blood Pressure Intervention Trial) demonstrated a 27% reduction in all-cause mortality with a systolic blood pressure (SBP) goal ofmellitus, stroke, or heart failure. To quantify the potential benefits and risks of SPRINT intensive goal implementation, we estimated the deaths prevented and excess serious adverse events incurred if the SPRINT intensive SBP treatment goal were implemented in all eligible US adults. METHODS: SPRINT eligibility criteria were applied to the 1999 to 2006 National Health and Nutrition Examination Survey and linked with the National Death Index through December 2011. SPRINT eligibility included age ≥50 years, SBP of 130 to 180 mm Hg (depending on the number of antihypertensive medications being taken), and high cardiovascular disease risk. Exclusion criteria were diabetes mellitus, history of stroke, \u3e1 g proteinuria, heart failure, estimated glomerular filtration ratemL·min RESULTS: The mean age was 68.6 years, and 83.2% and 7.4% were non-Hispanic white and non-Hispanic black, respectively. The annual mortality rate was 2.20% (95% confidence interval [CI], 1.91-2.48), and intensive SBP treatment was projected to prevent ≈107 500 deaths per year (95% CI, 93 300-121 200) and give rise to 56 100 (95% CI, 50 800-61 400) episodes of hypotension, 34 400 (95% CI, 31 200-37 600) episodes of syncope, 43 400 (95% CI, 39 400-47 500) serious electrolyte disorders, and 88 700 (95% CI, 80 400-97 000) cases of acute kidney injury per year. The analysis-of-extremes approach indicated that the range of estimated lower- and upper-bound number of deaths prevented per year with intensive SBP control was 34 600 to 179 600. Intensive SBP control was projected to prevent 46 100 (95% CI, 41 800-50 400) cases of heart failure annually. CONCLUSIONS: If fully implemented in eligible US adults, intensive SBP treatment could prevent ≈107 500 deaths per year. A consequence of this treatment strategy, however, could be an increase in serious adverse events

Stakeholder engagement in eight comparative effectiveness trials in African Americans and Latinos with asthma

BACKGROUND: The effects of stakeholder engagement, particularly in comparative effectiveness trials, have not been widely reported. In 2014, eight comparative effectiveness studies targeting African Americans and Hispanics/Latinos with uncontrolled asthma were funded by the Patient-Centered Outcomes Research Institute (PCORI) as part of its Addressing Disparities Program. Awardees were required to meaningfully involve patients and other stakeholders. Using specific examples, we describe how these stakeholders substantially changed the research protocols and in other ways participated meaningfully as full partners in the development and conduct of the eight studies. METHODS: Using the method content analysis of cases, we identified themes regarding the types of stakeholders, methods of engagement, input from the stakeholders, changes made to the research protocols and processes, and perceived benefits and challenges of the engagement process. We used summaries from meetings of the eight teams, results from an engagement survey, and the final research reports as our data source to obtain detailed information. The descriptive data were assessed by multiple reviewers using inductive and deductive qualitative methods and discussed in the context of engagement literature. RESULTS: Stakeholders participated in the planning, conduct, and dissemination phases of all eight asthma studies. All the studies included clinicians and community representatives as stakeholders. Other stakeholders included patients with asthma, their caregivers, advocacy organizations, and health-system representatives. Engagement was primarily by participation in advisory boards, although six of the eight studies (75%) also utilized focus groups and one-on-one interviews. Difficulty finding a time and location to meet was the most reported challenge to engagement, noted by four of the eight teams (50%). Other reported challenges and barriers to engagement included recruitment of stakeholders, varying levels of enthusiasm among stakeholders, controlling power dynamics, and ensuring that stakeholder involvement was reflected and had true influence on the project. CONCLUSION: Engagement-driven modifications led to specific changes in study design and conduct that were felt to have increased enrollment and the general level of trust and support of the targeted communities. The level of interaction described, between investigators and stakeholders in each study and between investigator-stakeholder groups, is-we believe-unprecedented and may provide useful guidance for other studies seeking to improve the effectiveness of community-driven research

Doctoral Recital

List of performers and performances

Integrations between Autonomous System and Modern Computing Techniques: A Mini-review

The emulation of human behavior for autonomous problem solving has been an interdisciplinary field of research. Generally, classical control systems are used for static environments, where external disturbances and changes in internal parameters can be fully modulated before or neglected during operation. However, classical control systems are inadequate at addressing environmental uncertainty. By contrast, autonomous systems, which were first studied in the field of control systems, can be applied in an unknown environment. This paper summarizes the state of the art autonomous systems by first discussing the definition, modeling, and system structure of autonomous systems and then providing a perspective on how autonomous systems can be integrated with advanced resources (e.g., the Internet of Things, big data, Over-the-Air, and federated learning). Finally, what comes after reaching full autonomy is briefly discussed

CYP2A6 metabolism in the development of smoking behaviors in young adults

Cytochrome P450 2A6 (CYP2A6) encodes the enzyme responsible for the majority of nicotine metabolism. Previous studies support that slow metabolizers smoke fewer cigarettes once nicotine dependent but provide conflicting results on the role of CYP2A6 in the development of dependence. By focusing on the critical period of young adulthood, this study examines the relationship of CYP2A6 variation and smoking milestones. A total of 1209 European American young adults enrolled in the Collaborative Study on the Genetics of Alcoholism were genotyped for CYP2A6 variants to calculate a previously well-validated metric that estimates nicotine metabolism. This metric was not associated with the transition from never smoking to smoking initiation nor with the transition from initiation to daily smoking (P > 0.4). But among young adults who had become daily smokers (n = 506), decreased metabolism was associated with increased risk of nicotine dependence (P = 0.03) (defined as Fagerström Test for Nicotine Dependence score ≥4). This finding was replicated in the Collaborative Genetic Study of Nicotine Dependence with 335 young adult daily smokers (P = 0.02). Secondary meta-analysis indicated that slow metabolizers had a 53 percent increased odds (OR = 1.53, 95 percent CI 1.11-2.11, P = 0.009) of developing nicotine dependence compared with normal metabolizers. Furthermore, secondary analyses examining four-level response of time to first cigarette after waking (>60, 31-60, 6-30, ≤5 minutes) demonstrated a robust effect of the metabolism metric in Collaborative Study on the Genetics of Alcoholism (P = 0.03) and Collaborative Genetic Study of Nicotine Dependence (P = 0.004), illustrating the important role of this measure of dependence. These findings highlight the complex role of CYP2A6 variation across different developmental stages of smoking behaviors

Predicted distribution of the Sunda Stink-badger Mydaus javanensis (Mammalia: Carnivora: Mephitidae) on Borneo

The Sunda stink-badger Mydaus javanensis is a small carnivore inhabiting the South-east Asian islands of Java, Sumatra, Borneo and Natuna Islands. It occurs in a wide variety of vegetation types and is presently listed by The IUCN Red List of Threatened Species as Least Concern. We analysed 15 (Balanced Model) or 77 (Spatial Filtering Model) location records to predict habitat suitability across Borneo. The analysis suggests that most of the suitable habitat is located in Sabah, northeast Sarawak and North Kalimantan. In addition, this species is also recorded, mostly historically, patchily in west Sarawak, and West, Central, South and East Kalimantan. Although this species appears to be disturbance-tolerant and is frequently observed in village areas, some conservation action – such as limiting large-scale forest conversion to oil palm plantations – is warranted because most lowland habitat is unprotected. Further research in central and southern Borneo needs to focus on showing if there are any further sizable populations. Also, hunting of Sunda stink-badger has been reported in some parts of Borneo and might be a possible driver for the species’s patchy distribution. More research is warranted to understand what determines the species’s distribution and density, based on which proper conservation strategies, if needed, can be developed to preserve the species

Predicted distribution of the yellow-throated marten Martes flavigula (Mammalia: Carnivora: Mustelidae) on Borneo

The yellow-throated marten Martes flavigula is a wide-ranging species across much of Asia. It is active mainly during the day, is semi-arboreal and has an omnivorous diet. On Borneo, it has a wide elevation range, from coastal lowland to lower montane habitat of 1700 m a.s.l. Records from camera-trapping and other wildlife surveys imply a widespread distribution, but the species is encountered less frequently than in many other parts of its global range. We collected a total of 195 occurrence records from all political units of Borneo except South Kalimantan. To reduce possibly confounding effects of sampling bias on habitat suitability we used 56 records in a Balanced Model and 94 records in a Spatial Filtering Model. Respondents’ opinions on habitat preference showed large variation, except for lowland and upland dipterocarp forests, which were consistently perceived as highly suitable; disturbed areas such as burnt forests and bare areas were perceived to be less favourable. The habitat suitability model predicted that the yellow-throated marten is widespread within Borneo, likely to occur in mosaics of lowland and upland forests, including old plantations and active logging areas; but unlikely to use young plantations and crops, perhaps including oil palm plantations. The effects of logging on yellow-throated marten are not well understood, yet the species’s population size on Borneo will depend on how tree plantations and logging concessions are managed and harvested. More surveys above about 1200 m a.s.l., where information is still limited, would enable more confident habitat assessments. Further research could determine if the Bornean subspecies, M. f. saba, could be a cryptic species

High-level integration of murine intestinal transcriptomics data highlights the importance of the complement system in mucosal homeostasis.

BACKGROUND: The mammalian intestine is a complex biological system that exhibits functional plasticity in its response to diverse stimuli to maintain homeostasis. To improve our understanding of this plasticity, we performed a high-level data integration of 14 whole-genome transcriptomics datasets from samples of intestinal mouse mucosa. We used the tool Centrality based Pathway Analysis (CePa), along with information from the Reactome database. RESULTS: The results show an integrated response of the mouse intestinal mucosa to challenges with agents introduced orally that were expected to perturb homeostasis. We observed that a common set of pathways respond to different stimuli, of which the most reactive was the Regulation of Complement Cascade pathway. Altered expression of the Regulation of Complement Cascade pathway was verified in mouse organoids challenged with different stimuli in vitro. CONCLUSIONS: Results of the integrated transcriptomics analysis and data driven experiment suggest an important role of epithelial production of complement and host complement defence factors in the maintenance of homeostasis