Megagauss 2.0 : a 10 capacitor system for production of megagauss fields for laser plasma experiments

textHigh magnetic fields greater than 100 Tesla applied to laser generated plasmas can generate unique and interesting conditions. High power laser systems at the University of Texas in the Center for Higher Energy Density Sciences readily produce short lived fusion plasmas in cluster targets. A strong magnetic field could increase fusion neutron yield and plasma confinement while providing a unique plasma physics environment. For this purpose, Sandia National Laboratories in collaboration with the University of Texas designed and constructed a pulsed power device to produce more than 2 megaamperes. This current produces strong magnetic fields in small coils with duration on the order of microseconds. At the University of Texas, tests with this device determined the operational characteristics. I will describe the behavior of this device with currents of approximately a megaamp and magnetic fields of more than 60 Tesla. Emphasis is placed on understanding the behavior of the fields and coils.Physic

Characterizing laser-heated plasma energy density distributions for magnetized liner inertial fusion

Magnetized Linear Inertial Fusion (MagLIF) is an inertial confinement fusion (ICF) concept being pursued at Sandia National Laboratories [1]. It uses fusion fuel preheating via a laser. A subsequent cylindrical liner implosion and magnetic flux compression brings this fuel to fusion conditions. Experiments on the Z-facility at Sandia have produced compelling neutron yields in the range of 10¹² n/shot [2]. Maximal and axially uniform energy density in the preheat plasma is important for MagLIF yield [1] [3]. We developed a preheat test platform at the Z-beamlet laser facility that includes surrogate helium gas cell targets. We fielded 2D multi-frame imaging diagnostics including shadowgraphy and x-ray pinhole cameras (PHC). Sound speed and blast wave plasma expansion provide methods for temperature and energy per unit length measurements, giving distributions across the axial length of the plasma. We used these measurements to compare energy density beyond a benchmark of 4 mm across a range of laser parameters, enabling comparisons between preheat configurations. Initial preheat configurations with a 2 ns early prepulse and a 3 ns long heating pulse produced very low energy densities of less than 200 J beyond 4 mm axially. We observed approximately a factor of 4 improvement in coupled energy beyond 4 mm from implementation of a 20 ns early prepulse. Combining a magnetic field, early prepulse, and 5 ns main heating pulse produced an approximate factor of five improvement in coupled energy beyond 4 mm. Without a magnetic field, the energy per unit length descends steeply with axial length. With a 17 T axially-oriented magnetic field, the axial energy density and temperature distribution becomes more uniform up to 6-8 mm, and total coupled energy beyond 4 mm increases by a factor in the range of 1.5-2. Transverse x-ray PHC images on magnetic field shots indicate that the laser heated region is narrower than the laser width. This is evidence for cross-field electron thermal conduction suppression and self-focusing. A Gaussian radial temperature distribution solves the diffusion equation with a diffusion coefficient that is a constant function of temperature, which is approximately the case for electron conduction above a certain temperature across magnetic field lines. This approximate temperature distribution produces a qualitatively similar x-ray profile to data if peak temperatures exceed 1.5 keV during heating. To our knowledge, we have the first indirect measurements of temperatures and energy densities in surrogate preheat plasmas, both with and without a magnetic field. The energy density and temperature distributions we have measured will provide a valuable comparison to simulations and inform both the design simulators of MagLIF and the experimental planners.Physic

Tracking Student Propositions in an Inquiry System

We built software to support student reasoning about a phenomenon and development of hypotheses to explain it. The goal is to engage students in asking questions, generating hypotheses and testing predictions. Rashi, an intelligent tutor, tracks students’ investigations (e.g., hypotheses, questions, data collection, and inferences) and helps articulate how evidence and theories are related. The tutor provides advice, such as recognizing when data does not support a hypothesis Cases are presented in geology, biology or engineering, and students are scaffolded to use an inquiry-based approach to posit a theory to explain the situation. Generic and reusable structured tools guide students through exploration of ill-structured problem spaces, supporting student knowledge and scaffolding reasoning and diagnostic skills

Long-term biocompatibility, imaging appearance and tissue effects associated with delivery of a novel radiopaque embolization bead for image-guided therapy

The objective of this study was to undertake a comprehensive long-term biocompatibility and imaging assessment of a new intrinsically radiopaque bead (LC Bead LUMI™) for use in transarterial embolization. The sterilized device and its extracts were subjected to the raft of ISO10993 biocompatibility tests that demonstrated safety with respect to cytotoxicity, mutagenicity, blood contact, irritation, sensitization, systemic toxicity and tissue reaction. Intra-arterial administration was performed in a swine model of hepatic arterial embolization in which 0.22–1 mL of sedimented bead volume was administered to the targeted lobe(s) of the liver. The beads could be visualized during the embolization procedure with fluoroscopy, DSA and single X-ray snapshot imaging modalities. CT imaging was performed before and 1 h after embolization and then again at 7, 14, 30 and 90 days. LC Bead LUMI™ could be clearly visualized in the hepatic arteries with or without administration of IV contrast and appeared more dense than soluble contrast agent. The CT density of the beads did not deteriorate during the 90 day evaluation period. The beads embolized predictably and effectively, resulting in areas devoid of contrast enhancement on CT imaging suggesting ischaemia-induced necrosis nearby the sites of occlusion. Instances of off target embolization were easily detected on imaging and confirmed pathologically. Histopathology revealed a classic foreign body response at 14 days, which resolved over time leading to fibrosis and eventual integration of the beads into the tissue, demonstrating excellent long-term tissue compatibility

Studying the [OIII]λ\lambda5007A emission-line width in a sample of ∼\sim80 local active galaxies: A surrogate for σ⋆\sigma_{\star}?

For a sample of $\sim$80 local ($0.02 \leq z \leq 0.1$) Seyfert-1 galaxies with high-quality long-slit Keck spectra and spatially-resolved stellar-velocity dispersion ($\sigma_{\star}$) measurements, we study the profile of the [OIII]$\lambda$5007A emission line to test the validity of using its width as a surrogate for $\sigma_{\star}$. Such an approach has often been used in the literature, since it is difficult to measure $\sigma_{\star}$ for type-1 active galactic nuclei (AGNs) due to the AGN continuum outshining the stellar-absorption lines. Fitting the [OIII] line with a single Gaussian or Gauss-Hermite polynomials overestimates $\sigma_{\star}$ by 50-100%. When line asymmetries from non-gravitational gas motion are excluded in a double Gaussian fit, the average ratio between the core [OIII] width ($\sigma_{\rm {[OIII],D}}$) and $\sigma_{\star}$ is $\sim$1, but with individual data points off by up to a factor of two. The resulting black-hole-mass-$\sigma_{\rm {[OIII],D}}$ relation scatters around that of quiescent galaxies and reverberation-mapped AGNs. However, a direct comparison between $\sigma_{\star}$ and $\sigma_{\rm {[OIII],D}}$ shows no close correlation, only that both quantities have the same range, average and standard deviation, probably because they feel the same gravitational potential. The large scatter is likely due to the fact that line profiles are a luminosity-weighted average, dependent on the light distribution and underlying kinematic field. Within the range probed by our sample (80-260 km s$^{-1}$), our results strongly caution against the use of [OIII] width as a surrogate for $\sigma_{\star}$ on an individual basis. Even though our sample consists of radio-quiet AGNs, FIRST radio-detected objects have, on average, a $\sim$10% larger [OIII] core width.Comment: 15 pages, 10 figures, 6 tables. Accepted for publication in the Monthly Notices of the Royal Astronomical Societ

Comparison of foam swabs and toothbrushes as oral hygiene interventions in mechanically ventilated patients: a randomised split mouth study

Abstract Introduction During critical illness, dental plaque may serve as a reservoir of respiratory pathogens. This study compared the effectiveness of toothbrushing with a small-headed toothbrush or a foam-headed swab in mechanically ventilated patients. Methods This was a randomised, assessor-blinded, split-mouth trial, performed at a single critical care unit. Adult, orally intubated patients with >20 teeth, where >24 hours of mechanical ventilation was expected were included. Teeth were cleaned 12-hourly using a foam swab or toothbrush (each randomly assigned to one side of the mouth). Cleaning efficacy was based on plaque scores, gingival index and microbial plaque counts. Results High initial plaque (mean=2.1 (SD 0.45)) and gingival (mean=2.0 (SD 0.54)) scores were recorded for 21 patients. A significant reduction compared with initial plaque index occurred using both toothbrushes (mean change=−1.26, 95% CI −1.57 to −0.95; p<0.001) and foam swabs (mean change=−1.28, 95% CI −1.54 to −1.01; p<0.001). There was significant reduction in gingival index over time using toothbrushes (mean change=−0.92; 95% CI −1.19 to −0.64; p<0.001) and foam swabs (mean change=−0.85; 95% CI −1.10 to −0.61; p<0.001). Differences between cleaning methods were not statistically significant (p=0.12 for change in gingival index; p=0.24 for change in plaque index). There was no significant change in bacterial dental plaque counts between toothbrushing (mean change 3.7×104 colony-forming units (CFUs); minimum to maximum (−2.5×1010 CFUs, 8.7×107 CFUs)) and foam swabs (mean change 9×104 CFUs; minimum to maximum (−3.1×1010 CFUs, 3.0×107 CFUs)). Conclusions Patients admitted to adult intensive care had poor oral health, which improved after brushing with a toothbrush or foam swab. Both interventions were equally effective at removing plaque and reducing gingival inflammation. Trial registration number NCT01154257; Pre-results

Pristine carbon nanotube scaffolds for the growth of chondrocytes

The effective growth of chondrocytes and the formation of cartilage is demonstrated on scaffolds of aligned carbon nanotubes; as two dimensional sheets and on three dimensional textiles. Raman spectroscopy is used to confirm the presence of chondroitin sulfate, which is critical in light of the unreliability of traditional dye based assays for carbon nanomaterial substrates. The textile exhibits a very high affinity for chondrocyte growth and could present a route to implantable, flexible cartilage scaffolds with tuneable mechanical properties

Parent-reported child appetite moderates relationships between child genetic obesity risk and parental feeding practices

BackgroundFood parenting practices are associated with child weight. Such associations may reflect the effects of parents' practices on children's food intake and weight. However, longitudinal, qualitative, and behavioral genetic evidence suggests these associations could, in some cases, reflect parents' response to children's genetic risk for obesity, an instance of gene–environment correlation. We tested for gene–environment correlations across multiple domains of food parenting practices and explored the role of parent-reported child appetite in these relationships.Materials and methodsData on relevant variables were available for N = 197 parent–child dyads (7.54 ± 2.67 years; 44.4% girls) participating in RESONANCE, an ongoing pediatric cohort study. Children's body mass index (BMI) polygenic risk score (PRS) were derived based on adult GWAS data. Parents reported on their feeding practices (Comprehensive Feeding Practices Questionnaire) and their child's eating behavior (Child Eating Behavior Questionnaire). Moderation effects of child eating behaviors on associations between child BMI PRS and parental feeding practices were examined, adjusting for relevant covariates.ResultsOf the 12 parental feeding practices, 2 were associated with child BMI PRS, namely, restriction for weight control (β = 0.182, p = 0.011) and teaching about nutrition (β = −0.217, p = 0.003). Moderation analyses demonstrated that when children had high genetic obesity risk and showed moderate/high (vs. low) food responsiveness, parents were more likely to restrict food intake to control weight.ConclusionOur results indicate that parents may adjust their feeding practices in response to a child's genetic propensity toward higher or lower bodyweight, and the adoption of food restriction to control weight may depend on parental perceptions of the child's appetite. Research using prospective data on child weight and appetite and food parenting from infancy is needed to further investigate how gene–environment relationships evolve through development

Author Correction: Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Correction to this paper has been published: https://doi.org/10.1038/s41467-020-20128-w

Author Correction:Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples (Nature Communications, (2020), 11, 1, (4748), 10.1038/s41467-020-18151-y)

The original version of this Article omitted from the author list the 9th author Yize Li, who is from the ‘The McDonnell Genome Institute at Washington University, St. Louis, MO 63108, USA and Department of Medicine, Division of Oncology, Washington University School of Medicine, St. Louis, MO 63108, USA’. This has been corrected in both the PDF and HTML versions of the Article