Machine-learning (ML) approaches have proven to be of great utility in modern materials innovation pipelines. Generally, ML models are trained on predetermined past data and then used to make predictions for new test cases. Active-learning, however, is a paradigm in which ML models can direct the learning process itself through providing dynamic suggestions/queries for the “next-best experiment.” In this work, the authors demonstrate how an active-learning framework can aid in the discovery of polymers possessing high glass transition temperatures (Tg). Starting from an initial small dataset of polymer Tg measurements, the authors use Gaussian process regression in conjunction with an active-learning framework to iteratively add Tg measurements of candidate polymers to the training dataset. The active-learning framework employs one of three decision making strategies (exploitation, exploration, or balanced exploitation/exploration) for selection of the “next-best experiment.” The active-learning workflow terminates once 10 polymers possessing a Tg greater than a certain threshold temperature are selected. The authors statistically benchmark the performance of the aforementioned three strategies (against a random selection approach) with respect to the discovery of high-Tg polymers for this particular demonstrative materials design challenge.

A mother's nutritional choices while pregnant may have a great influence on her baby's development in the womb and during infancy. There is evidence that what a mother eats during pregnancy interacts with her genes to affect her child's susceptibility to poor health outcomes including childhood obesity, pre-diabetes, allergy and asthma. Furthermore, after what an infant eats can change his or her intestinal bacteria, which can further influence the development of these poor outcomes. In the present paper, we review the importance of birth cohorts, the formation and early findings from a multi-ethnic birth cohort alliance in Canada and summarise our future research directions for this birth cohort alliance. We summarise a method for harmonising collection and analysis of self-reported dietary data across multiple cohorts and provide examples of how this birth cohort alliance has contributed to our understanding of gestational diabetes risk; ethnic and diet-influences differences in the healthy infant microbiome; and the interplay between diet, ethnicity and birth weight. Ongoing work in this birth cohort alliance will focus on the use of metabolomic profiling to measure dietary intake, discovery of unique diet–gene and diet–epigenome interactions, and qualitative interviews with families of children at risk of metabolic syndrome. Our findings to-date and future areas of research will advance the evidence base that informs dietary guidelines in pregnancy, infancy and childhood, and will be relevant to diverse and high-risk populations of Canada and other high-income countries.

Populations of Critically Endangered White-rumped Gyps bengalensis and Slender-billed G. tenuirostris Vultures in Nepal declined rapidly during the 2000s, almost certainly because of the effects of the use in livestock of the non-steroidal anti-inflammatory drug diclofenac, which is nephrotoxic to Gyps vultures. In 2006, veterinary use of diclofenac was banned in Nepal and this was followed by the gradual implementation, over most of the geographical range of the two vulture species in Nepal, of a Vulture Safe Zone (VSZ) programme to advocate vulture conservation, raise awareness about diclofenac, provide vultures with NSAID-free food and encourage the veterinary use in livestock of a vulture-safe alternative NSAID (meloxicam). We report the results of long-term monitoring of vulture populations in Nepal before and after this programme was implemented, by means of road transects. Piecewise regression analysis of the count data indicated that a rapid decline of the White-rumped Vulture population from 2002 up to about 2013 gave way to a partial recovery between about 2013 and 2018. More limited data for the Slender-billed Vulture indicated that a rapid decline also gave way to partial recovery from about 2012 onwards. The rates at which populations were increasing in the 2010s exceeded the upper end of the range of increase rates expected in a closed population under optimal conditions. The possibility that immigration from India is contributing to the changes cannot be excluded. We present evidence from open and undercover pharmacy surveys that the VSZ programme had apparently become effective in reducing the availability of diclofenac in a large part of the range of these species in Nepal by about 2011. Hence, community-based advocacy and awareness-raising actions, and possibly also provisioning of safe food, may have made an important contribution to vulture conservation by augmenting the effects of changes in the regulation of toxic veterinary drugs.

Political scientists commonly use survey experiments–often conducted online–to study the attitudes of the mass public. In these experiments, compensation is usually small and researcher control is limited, which introduces the potential for low respondent effort and attention. This lack of engagement may result in noncompliance with experimental protocols, threatening causal inferences. However, in reviewing the literature, we find that despite the discipline’s general familiarity with experimental noncompliance, researchers rarely consider it when analyzing survey experiments. This oversight is important because it may unknowingly prevent researchers from estimating their causal quantities of greatest substantive interest. We urge scholars to address this particular manifestation of an otherwise familiar problem and suggest two strategies for formally measuring noncompliance in survey experiments: recording vignette screen time latency and repurposing manipulation checks. We demonstrate and discuss the substantive consequences of these recommendations by revisiting several published survey experiments.

OBJECTIVES/SPECIFIC AIMS: The purpose of the study was to describe patient characteristics associated with subsequent development of bowel ischemia. Primary outcomes were survival to discharge, 30-day and 1-year survival in patients with LVAD who subsequently develop bowel ischemia. Secondary outcomes included characteristics of patients who survive to discharge after bowel ischemia and those who do not. These included markers of patient condition prior to surgical/endoscopic intervention such as lactate levels, ICU admission, ventilator dependence, vasopressor and renal replacement requirements, as well as presence of sepsis. Of these, we predicted that lactate levels and white blood cell count would be significantly elevated pre- and post-operatively in patients who do not recover from bowel ischemic event. We used Mann-Whitney U Test to examine lactate levels between the two groups as our sample size was <30 and therefore necessitated the use of non-parametric testing. METHODS/STUDY POPULATION: In this single-center retrospective study, we analyzed all patients who underwent durable, CF-LVAD implantation at Duke University Medical Center (DUMC) between January 2008 and November 2018. Patients were screened using CPT codes for abdominal surgical exploration or ICD codes for intestinal vascular insufficiency. Final cohort was selected with confirmed diagnosis of intestinal ischemia based on surgical exploration or endoscopic intervention. Patient characteristics including pre-LVAD comorbidities, indication for LVAD implant, and clinical picture prior to bowel ischemic event were collected. Specific characteristics related to bowel ischemia were summarized, including diagnostic imaging, time from imaging study to operative intervention, and intraoperative details. Patient outcomes including survival to discharge, 30-day-, and 1-year survival were summarized. Patients were stratified based on survival to discharge status. Continuous variables were reported as median and interquartile range and compared using Mann-Whitney U test. Categorical variables were reported as proportions and compared using Fisher’s exact test as appropriate. RESULTS/ANTICIPATED RESULTS: A total of 754 patients underwent durable, CF-LVAD implant at DUMC, of which 21 subsequently developed intestinal ischemia (incidence 2.8%). The majority were male (81%) and treated as destination therapy (76.2%). Ten patients (50%) survived to discharge (one remains hospitalized). The proportions of patients receiving HeartMate II (60% vs. 50%, p=1.0), HeartMate III (20% vs. 10%, p=1.0), and HeartWare (20% vs. 40%, p=0.6) were not significantly different between patients who survived to discharge and patients who did not. Median time from LVAD implant to diagnosis of bowel ischemia did not vary significantly between the patient groups (11.5 days, IQR 34.75 vs. 16.5 days, IQR 173.8; p=0.40), nor did the median time from diagnosis to surgical intervention (264.5 minutes, IQR 497.8 vs. 323 minutes, IQR 440, p=0.82). In the 48 hours leading to diagnosis and intervention, renal replacement therapy (50% vs. 0%, p=0.033) was more prevalent in patients who did not survive to discharge. Differences in pre- and post-operative lactate levels were not significantly different in patient groups. A similar pattern of diagnostic study preference emerged from both groups, with CT being the most common (76.2%) followed by KUB (42.9%). Upper endoscopy/colonoscopy was performed in 7 patients (33.3%), of which 5 also had operative exploration. A total of 19 patients underwent abdominal exploration (90.5%). Nine had large bowel resection (42.9%) while 14 had small bowel resection (66.7% with average 75cm removed). Overall survival at 1-year was 33%. For those making it to discharge (n=10), one year survival was 60%. DISCUSSION/SIGNIFICANCE OF IMPACT: This is the first institutional study to our knowledge to describe intestinal ischemia in patients receiving CF-LVAD therapy. Intestinal ischemia in patients receiving CF-LVAD therapy is associated with high mortality and morbidity. Diagnosis of bowel ischemia should be considered in patients presenting with clinical symptoms of bowel ischemia in addition to requirement of renal replacement therapy. Imaging modalities used were dependent on the clinical situation and were not always necessary prior to intervention. Further investigation is warranted to identify predictors of this morbid complication.

The control segment in satellite navigation systems is responsible for estimating satellite orbit and clock bias which is required for a reliable Position, Navigation and Timing (PNT) user service. Initial orbit determination is a crucial step which accounts for all unknowns/anomalous parameters such as satellite orbit manoeuvres, on board and receiver clock frequency variations and environmental effects. It is vital that the estimates of the orbits and clock are insensitive to these factors. In this paper, an initial orbit determination method is presented using existing robust methodology for estimation of initial satellite position and its propagation using a variant of the Kalman Filter (KF) which allows the initial position determination process to be independent of satellite and receiver anomalies. The derivation of this KF variant is presented. Preliminary results obtained from simulated data are shown. The said method is checked for robustness by comparing results obtained for a given satellite position data set with that from the conventional Kalman Filter. The conventional KF exhibits divergence due to anomalies which are eliminated by the use of the method presented in this paper.

We present a flexible linear optimization model for correcting multi-angle curtaining effects in plasma focused ion beam scanning electron microscopy (PFIB-SEM) images produced by rocking-polishing schemes. When PFIB-SEM is employed in a serial sectioning tomography workow, it is capable of imaging large three-dimensional volumes quickly, providing rich information in the critical 10–100 nm feature length scale. During tomogram acquisition, a “rocking polish” is often used to reduce straight-line “curtaining” gradations in the milled sample surface. While this mitigation scheme is effective for deep curtains, it leaves shallower line artifacts at two discretized angles. Segmentation and other automated processing of the image set requires that these artifacts be corrected for accurate microstructural quantification. Our work details a new Fourier-based linear optimization model for correcting curtaining artifacts by targeting curtains at two discrete angles. We demonstrate its capabilities by processing images from a tomogram from a multiphase, heterogeneous concrete sample. We present methods for selecting the parameters which meet the user’s goals most appropriately. Compared to previous works, we show that our model provides effective multi-angle curtain correction without introducing artifacts into the image, modifying non-curtain structures or causing changes to the contrast of voids. Our algorithm can be easily parallelized to take advantage of multi-core hardware.

The effect of an electric field on the coalescence of two water drops suspended in an insulating oil is investigated. We report four new results. (i) The cone angle for the non-coalescence of drops can be significantly smaller (as small as $19^{\circ }$ ) than the value of $30.8^{\circ }$ reported by Bird et al. (Phys. Rev. Lett., vol. 103 (16), 2009, 164502). (ii) A surprising observation of the dependence of the mode of coalescence/non-coalescence on the type of insulating oil is seen. A cone–cone mode for silicone oil is observed as against cone–dimple mode for castor oil. (iii) The critical capillary number for non-coalescence decreases with increase in the conductivity of the droplet phase. (iv) Systematic experiments prove that the apparent bridge during non-coalescence is indeed transitory and not permanent, as reported elsewhere. Theoretical calculations using analytical theory and the boundary integral method explain the formation of the cone–dimple mode as well as the transitory bridge length. The numerical calculation and thereby the physical mechanism to explain the occurrence of very small non-coalescence angles as well as the dependence of the phenomenon on the conductivity of the insulating oil and the water droplets remain unexplained.

In recent work, Teele and Thelen (2017) documented the underrepresentation of female-authored scholarship in a broad selection of political science journals. To better understand these patterns, we present the results of an original, individual-level survey of political scientists conducted in the spring of 2017. Confirming Teele and Thelen’s speculation, our evidence indicates that differences in submission rates underlie the gender gap in publication—a pattern particularly pronounced for the discipline’s “top three” journals. Leveraging original survey items, we pursue explanations of the submission gap, finding that both methodological specialization and attitudes toward publication strategies play roles. Importantly, we also conclude that men and women obtain differential returns on their investments in coauthorship: although male and female respondents report identical propensities to coauthor, coauthorship boosts submission and publication rates more strongly for men than women. We discuss the implications of our findings for ongoing conversations about inequality in political science.