Structural and Mechanical Changes of Soft and Firm Polyurethane Stents: A Benchtop Study

INTRODUCTION AND OBJECTIVES: Ureteral stents help relieve obstruction and maintain ureteral drainage. However, chronic indwelling stents carry complications including fragmentation, migration, and encrustation. Other than indwelling time, factors contributing to stent encrustation are unknown. The purpose of this study is to compare the risk for encrustation and force required for removal in soft, firm, multi-length, and fixed length stents in a controlled artificial urine bath. METHODS: Twenty four double pigtail stent coils (6 firm multi-length, 6 soft multi-length soft, 6 firm fixed length, 6 soft fixed length stent coils) were bathed in an vitro artificial urine solution to stimulate a rapid encrustation model. The stents were bathed for 15 days in an incubator at human body temperature. The urine bath was exchanged every 3 days and the length and diameter of the stent coils were measured. The force required for stent extraction from a ureteral benchtop model was measured using a force gauge before and after the urine bath. Mann-Whitney U test was used for statistical analysis with p\u3c0.05 considered significant. RESULTS: After 15 days, all stents showed evidence of encrustation on gross evaluation and scanning electron microscopy. The mean force required for stent removal after the urine bath was 0.664N (firm fixed), 0.549N (firm multi), 0.502N (soft fixed), 0.475N (soft multi). Firm stents required significantly more force for removal than soft stents prior to the urine bath (0.290N vs 0.162N respectively; p\u3c0.001) and after the urine bath (0.606N vs 0.488N respectively; p=0.01) regardless of whether these stents were fixed or multi-length. Soft stents increased in both length (9.5 to 12.7 cm; p\u3c0.001) and diameter (1.4 to 3.3 mm; p\u3c0.001) while firm stents only increased in diameter (1.4 to 2.3 mm; p\u3c0.001). CONCLUSIONS: Signs of stent encrustation occurred as early as 15 days. While firm stents required more force for removal, soft stents demonstrated significant spatial changes in vitro. These transformations should be considered at time of stent selection to optimize patient comfort and quality of life

Cats with thermal burn injuries from California wildfires show echocardiographic evidence of myocardial thickening and intracardiac thrombi.

Recent increases in the prevalence and severity of wildfires in some regions have resulted in an increased frequency of veterinary burn patients. Few studies exist regarding diagnostics and management of burn wounds in veterinary patients and current knowledge is extrapolated from human literature and research models. Post-burn cardiac injury is a common finding and predictor of mortality in human patients and echocardiography is an important tool in monitoring response to therapy and predicting outcome. We describe the notable findings from cats naturally exposed to California wildfires in 2017 and 2018. Domestic cats (n = 51) sustaining burn injuries from the Tubbs (2017) and Camp (2018) wildfires were prospectively enrolled and serial echocardiograms and cardiac troponin I evaluations were performed. Echocardiograms of affected cats revealed a high prevalence of myocardial thickening (18/51) and spontaneous echocardiographic contrast and thrombi formation (16/51). Forty-two cats survived to discharge and 6 died or were euthanized due to a possible cardiac cause. For the first time, we describe cardiovascular and coagulation effects of thermal burn and smoke inhalation in cats. Further studies in veterinary burn victims are warranted and serve as a translational research opportunity for uncovering novel disease mechanisms and therapies

A Preliminary Roadmap for LLMs as Assistants in Exploring, Analyzing, and Visualizing Knowledge Graphs

We present a mixed-methods study to explore how large language models (LLMs) can assist users in the visual exploration and analysis of knowledge graphs (KGs). We surveyed and interviewed 20 professionals from industry, government laboratories, and academia who regularly work with KGs and LLMs, either collaboratively or concurrently. Our findings show that participants overwhelmingly want an LLM to facilitate data retrieval from KGs through joint query construction, to identify interesting relationships in the KG through multi-turn conversation, and to create on-demand visualizations from the KG that enhance their trust in the LLM's outputs. To interact with an LLM, participants strongly prefer a chat-based 'widget,' built on top of their regular analysis workflows, with the ability to guide the LLM using their interactions with a visualization. When viewing an LLM's outputs, participants similarly prefer a combination of annotated visuals (e.g., subgraphs or tables extracted from the KG) alongside summarizing text. However, participants also expressed concerns about an LLM's ability to maintain semantic intent when translating natural language questions into KG queries, the risk of an LLM 'hallucinating' false data from the KG, and the difficulties of engineering a 'perfect prompt.' From the analysis of our interviews, we contribute a preliminary roadmap for the design of LLM-driven knowledge graph exploration systems and outline future opportunities in this emergent design space

Sn-modification of Pt7/alumina model catalysts: Suppression of carbon deposition and enhanced thermal stability.

An atomic layer deposition process is used to modify size-selected Pt7/alumina model catalysts by Sn addition, both before and after Pt7 cluster deposition. Surface science methods are used to probe the effects of Sn-modification on the electronic properties, reactivity, and morphology of the clusters. Sn addition, either before or after cluster deposition, is found to strongly affect the binding properties of a model alkene, ethylene, changing the number and type of binding sites, and suppressing decomposition leading to carbon deposition and poisoning of the catalyst. Density functional theory on a model system, Pt4Sn3/alumina, shows that the Sn and Pt atoms are mixed, forming alloy clusters with substantial electron transfer from Sn to Pt. The presence of Sn also makes all the thermally accessible structures closed shell, such that ethylene binds only by π-bonding to a single Pt atom. The Sn-modified catalysts are quite stable in repeated ethylene temperature programmed reaction experiments, suggesting that the presence of Sn also reduces the tendency of the sub-nano-clusters to undergo thermal sintering

Tracking The Field: Volume 5 - Analyzing Trends In Environmental Grantmaking

This report builds on the Environmental Grantmakers Association's (EGA) grant research from 2007 to 2013, deepening our understanding of trends and gaps in environmental philanthropy.Analyzing grant data from the supply side of funding within the environment movement, the Tracking the Field report provides an avenue for EGA members to see where their grantmaking fits into the larger environmental movement and how they can optimize their grant dollars to be more strategic and effective.Tracking the Field: Volume 5 analyzes 66,340 grants, totaling more than $6.8 billion between 2007 and 2013. With six grant years of data, we are able to see the impact of outside influences on environmental philanthropy in addition to shifts within the field

Peer Knowledge Sharing Outside the Undergraduate STEM Classroom

Student interest is associated with persistence in STEM courses of study (Maltese, Melki, Wiebke, 2014). If peers decide, of their own accord, to discuss knowledge among each other outside of the classroom context, the behavior is indicative of deepening interest in the information being shared (Renninger Hidi, 2002). Understanding outside classroom knowledge sharing behaviors among peers involved in a STEM course may help educators construct learning contexts that promote interest and persistence in STEM subjects. To that end, this study examined two important research questions: (1) what are the key factors that influence peer to peer knowledge sharing outside the classroom? and (2) what are the methods the student use to share content knowledge? In order to explore these questions, a qualitative study was designed to explore knowledge sharing between peers outside the classroom. A semi-structured interview protocol with eight students from a Mid-Atlantic community college was conducted to explore students’ perceptions of knowledge sharing between peers. Data were coded and analyzed by a group of researchers and themes were identified and theoretical and practical implications of the study were recorded. Several key facilitators of knowledge sharing were identified: self-efficacy, interpersonal relationships, interpersonal similarity and media richness. Implications for teachers are presented. Limitations and future research are included in the end of the study. Keywords: knowledge sharing, peer to peer, peer learning, knowledge transfer, content knowledge, college science teaching, community colleg

A correlation-test-based validation procedure for identified neural networks

In this study, an enhanced correlation-test-based validation procedure is developed to check the quality of identified neural networks in modeling of nonlinear systems. The new computation algorithm upgrades the validation power by including a direct correlation test between residuals and delayed outputs that have been quoted indirectly in the most previous approaches. Furthermore, based on the new validation procedure, three guidelines are proposed in this study to help explain the validation results and the statistic properties of the residuals. It is hoped that this study could promote awareness of why the correlation tests are an effective method of validating identified neural networks, and provide examples how to use the tests in user applications. © 2008 IEEE