4,987 research outputs found
Wind song: song with piano accompaniment
https://digitalcommons.ithaca.edu/sheetmusic/1171/thumbnail.jp
Exoplanet atmosphere evolution: emulation with random forests
Atmospheric mass-loss is known to play a leading role in sculpting the
demographics of small, close-in exoplanets. Understanding the impact of such
mass-loss driven evolution requires modelling large populations of planets to
compare with the observed exoplanet distributions. As the quality of planet
observations increases, so should the accuracy of the models used to understand
them. However, to date, only simple semi-analytic models have been used in such
comparisons since modelling populations of planets with high accuracy demands a
high computational cost. To address this, we turn to machine learning. We
implement random forests trained on atmospheric evolution models, including XUV
photoevaporation, to predict a given planet's final radius and atmospheric
mass. This evolution emulator is found to have an RMS fractional radius error
of 1 from the original models and is times faster to evaluate.
As a test case, we use the emulator to infer the initial properties of
Kepler-36b and c, confirming that their architecture is consistent with
atmospheric mass loss. Our new approach opens the door to highly sophisticated
models of atmospheric evolution being used in demographic analysis, which will
yield further insight into planet formation and evolution.Comment: 5 pages, 3 figures. Submitted to MNRAS letter
Recommended from our members
Early changes in pro-inflammatory cytokine levels in neonates with encephalopathy are associated with remote epilepsy.
BackgroundNeonatal seizures are associated with adverse neurologic sequelae including epilepsy in childhood. Here we aim to determine whether levels of cytokines in neonates with brain injury are associated with acute symptomatic seizures or remote epilepsy.MethodsThis is a cohort study of term newborns with encephalopathy at UCSF between 10/1993 and 1/2000 who had dried blood spots. Maternal, perinatal/postnatal, neuroimaging, and epilepsy variables were abstracted by chart review. Logistic regression was used to compare levels of cytokines with acute seizures and the development of epilepsy.ResultsIn a cohort of 26 newborns with neonatal encephalopathy at risk for hypoxic ischemic encephalopathy with blood spots for analysis, diffuse alterations in both pro- and anti-inflammatory cytokine levels were observed between those with (11/28, 39%) and without acute symptomatic seizures. Seventeen of the 26 (63%) patients had >2 years of follow-up and 4/17 (24%) developed epilepsy. Higher levels of pro-inflammatory cytokines IL-6 and TNF-α within the IL-1β pathway were significantly associated with epilepsy.ConclusionsElevations in pro-inflammatory cytokines in the IL-1β pathway were associated with later onset of epilepsy. Larger cohort studies are needed to confirm the predictive value of these circulating biomarkers
Ramipril for claudication?
This ACE inhibitor can help patients with peripheral artery disease walk longer while remaining pain free
"Making Safety Happen" Through Probabilistic Risk Assessment at NASA
NASA is using Probabilistic Risk Assessment (PRA) as one of the tools in its Safety & Mission Assurance (S&MA) tool belt to identify and quantify risks associated with human spaceflight. This paper discusses some of the challenges and benefits associated with developing and using PRA for NASA human space programs. Some programs have entered operation prior to developing a PRA, while some have implemented PRA from the start of the program. It has been observed that the earlier a design change is made in the concept or design phase, the less impact it has on cost and schedule. Not finding risks until the operation phase yields much costlier design changes and major delays, which can result in discussions of just accepting the risk. Risk contributors identified by PRA are not just associated with hardware failures. They include but are not limited to crew fatality due to medical causes, the environment the vehicle and crew are exposed to, the software being used, and the reliability of the crew performing required actions. Some programs have entered operation prior to developing a PRA, and while PRA can still provide a benefit for operations and future design trades, the benefit of implementing PRA from the start of the program provides the added benefit of informing design and reducing risk early in program development. Currently, NASAs International Space Station (ISS) program is in its 20th year of on-orbit operations around the Earth and has several new programs in the design phase preparing to enter the operation phase all of which have active (or living) PRAs. These programs incorporate PRA as part of their Risk-Informed, Decision-Making (RIDM) process. For new NASA human spaceflight programs discussion begins with mission concept, establishing requirements, forming the PRA team, and continues through the design cycles into the operational phase. Several examples of PRA related applications and observed lessons are included
Is native speaker intuition reliable for high-frequency context creation?
This study determined whether native speaker intuition could be relied upon to producecontextual content that mostly fell into what is considered high-frequency vocabulary. Native speakers wrote over 160,000 tokens worth of example sentences for high-frequency multi-word units derived from a corpus. The resulting database was examined to determine whether the content added by the native speakers mostly stayed within the high-frequency realm.Results showed that not only did the vast majority of native speakers\u27 tokens fall into the high-frequency realm, the percentage that fell into the high-frequency realm only dropped by 0.84 percent in comparison to the multi-word units alone despite the large amount of data beingadded. This study highlighted how the intuition of experienced ESL practitioners can be relied upon to produce high-frequency contextual content
Early changes in brain structure correlate with language outcomes in children with neonatal encephalopathy.
Global patterns of brain injury correlate with motor, cognitive, and language outcomes in survivors of neonatal encephalopathy (NE). However, it is still unclear whether local changes in brain structure predict specific deficits. We therefore examined whether differences in brain structure at 6 months of age are associated with neurodevelopmental outcomes in this population. We enrolled 32 children with NE, performed structural brain MR imaging at 6 months, and assessed neurodevelopmental outcomes at 30 months. All subjects underwent T1-weighted imaging at 3 T using a 3D IR-SPGR sequence. Images were normalized in intensity and nonlinearly registered to a template constructed specifically for this population, creating a deformation field map. We then used deformation based morphometry (DBM) to correlate variation in the local volume of gray and white matter with composite scores on the Bayley Scales of Infant and Toddler Development (Bayley-III) at 30 months. Our general linear model included gestational age, sex, birth weight, and treatment with hypothermia as covariates. Regional brain volume was significantly associated with language scores, particularly in perisylvian cortical regions including the left supramarginal gyrus, posterior superior and middle temporal gyri, and right insula, as well as inferior frontoparietal subcortical white matter. We did not find significant correlations between regional brain volume and motor or cognitive scale scores. We conclude that, in children with a history of NE, local changes in the volume of perisylvian gray and white matter at 6 months are correlated with language outcome at 30 months. Quantitative measures of brain volume on early MRI may help identify infants at risk for poor language outcomes
A critical role for the Sp1-binding sites in the transforming growth factor-β-mediated inhibition of lipoprotein lipase gene expression in macrophages
Increasing evidence suggests that the cytokine transforming growth factor-β (TGF-β) inhibits the development of atherosclerosis. The lipoprotein lipase (LPL) enzyme expressed by macrophages has been implicated in the pathogenesis of atherosclerosis by stimulating the uptake of lipoprotein particles. Unfortunately, the action of TGF-β on the expression of LPL in macrophages remains largely unclear. We show that TGF-β inhibits LPL gene expression at the transcriptional level. Transient transfection assays reveal that the −31/+187 sequence contains the minimal TGF-β-responsive elements. Electrophoretic mobility shift assays show that Sp1 and Sp3 interact with two regions in the −31/+187 sequence. Mutations of these Sp1/Sp3 sites abolish the TGF-β-mediated suppression whereas multimers of the sequence impart the response to a heterologous promoter. TGF-β has no effect on the binding or steady-state polypeptide levels of Sp1 and Sp3. These results, therefore, suggest a novel mechanism for the TGF-β-mediated repression of LPL gene transcription that involves regulation of the action of Sp1 and Sp3
- …