Modeling the Formation of Giant Planet Cores I: Evaluating Key Processes

One of the most challenging problems we face in our understanding of planet formation is how Jupiter and Saturn could have formed before the the solar nebula dispersed. The most popular model of giant planet formation is the so-called 'core accretion' model. In this model a large planetary embryo formed first, mainly by two-body accretion. This is then followed by a period of inflow of nebular gas directly onto the growing planet. The core accretion model has an Achilles heel, namely the very first step. We have undertaken the most comprehensive study of this process to date. In this study we numerically integrate the orbits of a number of planetary embryos embedded in a swarm of planetesimals. In these experiments we have included: 1) aerodynamic gas drag, 2) collisional damping between planetesimals, 3) enhanced embryo cross-sections due to their atmospheres, 4) planetesimal fragmentation, and 5) planetesimal driven migration. We find that the gravitational interaction between the embryos and the planetesimals lead to the wholesale redistribution of material - regions are cleared of material and gaps open near the embryos. Indeed, in 90% of our simulations without fragmentation, the region near that embryos is cleared of planetesimals before much growth can occur. The remaining 10%, however, the embryos undergo a burst of outward migration that significantly increases growth. On timescales of ~100,000 years, the outer embryo can migrate ~6 AU and grow to roughly 30 Earth-masses. We also find that the inclusion of planetesimal fragmentation tends to inhibit growth.Comment: Accepted to AJ, 62 pages 11 figure

Magnitude Judgements Are Influenced by the Relative Positions of Data Points Within Axis Limits

When visualising data, chart designers have the freedom to choose the upper and lower limits of numerical axes. Axis limits can determine the physical characteristics of plotted values, such as the physical position of data points in dot plots. In two experiments (total N=300), we demonstrate that axis limits affect viewers' interpretations of the magnitudes of plotted values. Participants did not simply associate values presented at higher vertical positions with greater magnitudes. Instead, participants considered the relative positions of data points within the axis limits. Data points were considered to represent larger values when they were closer to the end of the axis associated with greater values, even when they were presented at the bottom of a chart. This provides further evidence of framing effects in the display of data, and offers insight into the cognitive mechanisms involved in assessing magnitude in data visualisations

Validity of the international physical activity questionnaire short form (IPAQ-SF): A systematic review

<p>Abstract</p> <p>Background</p> <p>The International Physical Activity Questionnaire - Short Form (IPAQ-SF) has been recommended as a cost-effective method to assess physical activity. Several studies validating the IPAQ-SF have been conducted with differing results, but no systematic review of these studies has been reported.</p> <p>Methods</p> <p>The keywords "IPAQ", "validation", and "validity" were searched in PubMed and Scopus. Studies published in English that validated the IPAQ-SF against an objective physical activity measuring device, doubly labeled water, or an objective fitness measure were included.</p> <p>Results</p> <p>Twenty-three validation studies were included in this review. There was a great deal of variability in the methods used across studies, but the results were largely similar. Correlations between the total physical activity level measured by the IPAQ-SF and objective standards ranged from 0.09 to 0.39; none reached the minimal acceptable standard in the literature (0.50 for objective activity measuring devices, 0.40 for fitness measures). Correlations between sections of the IPAQ-SF for vigorous activity or moderate activity level/walking and an objective standard showed even greater variability (-0.18 to 0.76), yet several reached the minimal acceptable standard. Only six studies provided comparisons between physical activity levels derived from the IPAQ-SF and those obtained from objective criterion. In most studies the IPAQ-SF overestimated physical activity level by 36 to 173 percent; one study underestimated by 28 percent.</p> <p>Conclusions</p> <p>The correlation between the IPAQ-SF and objective measures of activity or fitness in the large majority of studies was lower than the acceptable standard. Furthermore, the IPAQ-SF typically overestimated physical activity as measured by objective criterion by an average of 84 percent. Hence, the evidence to support the use of the IPAQ-SF as an indicator of relative or absolute physical activity is weak.</p

ECORD geophysical and geotechnical hazard site survey offshore Yucatan, Mexico : cruise 2013/4_ECORD

This report provides information on the University of Texas, Institute for Geophysics (UTIG) led ECORD (European Consortium for Ocean Research Drilling) geophysical and geotechnical hazard site survey offshore Yucatan aboard the R/V Justo Sierra which took place from the 16th April to the 23rd April 2013 over a study area within the Chixculub impact crater. The cruise has been carried out under contract for ECORD comprising the acquisition of geophysical data (surface tow boomer, side scan sonar, multibeam echosounder, magnetometer and CHIRP data) and geotechnical data (cone penetrometer tests (CPT)), ahead of scheduled ECORD led drilling of the Chixculub impact crater. The survey was undertaken in joint collaboration between UTIG and Universidad Nacional Autonóma de México (UNAM). Seafloor Geotec, LLC, was commissioned to carry out CPTs at selected sites within the survey area

Transient receptor potential melastatin 7 cation channel kinase new player in angiotensin II–induced hypertension

Transient receptor potential melastatin 7 (TRPM7) is a bifunctional protein comprising a magnesium (Mg2+)/cation channel and a kinase domain. We previously demonstrated that vasoactive agents regulate vascular TRPM7. Whether TRPM7 plays a role in the pathophysiology of hypertension and associated cardiovascular dysfunction is unknown. We studied TRPM7 kinase–deficient mice (TRPM7Δkinase; heterozygous for TRPM7 kinase) and wild-type (WT) mice infused with angiotensin II (Ang II; 400 ng/kg per minute, 4 weeks). TRPM7 kinase expression was lower in heart and aorta from TRPM7Δkinase versus WT mice, effects that were further reduced by Ang II infusion. Plasma Mg2+ was lower in TRPM7Δkinase versus WT mice in basal and stimulated conditions. Ang II increased blood pressure in both strains with exaggerated responses in TRPM7Δkinase versus WT groups (P&lt;0.05). Acetylcholine-induced vasorelaxation was reduced in Ang II–infused TRPM7Δkinase mice, an effect associated with Akt and endothelial nitric oxide synthase downregulation. Vascular cell adhesion molecule–1 expression was increased in Ang II–infused TRPM7 kinase–deficient mice. TRPM7 kinase targets, calpain, and annexin-1, were activated by Ang II in WT but not in TRPM7Δkinase mice. Echocardiographic and histopathologic analysis demonstrated cardiac hypertrophy and left ventricular dysfunction in Ang II–treated groups. In TRPM7 kinase–deficient mice, Ang II–induced cardiac functional and structural effects were amplified compared with WT counterparts. Our data demonstrate that in TRPM7Δkinase mice, Ang II–induced hypertension is exaggerated, cardiac remodeling and left ventricular dysfunction are amplified, and endothelial function is impaired. These processes are associated with hypomagnesemia, blunted TRPM7 kinase expression/signaling, endothelial nitric oxide synthase downregulation, and proinflammatory vascular responses. Our findings identify TRPM7 kinase as a novel player in Ang II–induced hypertension and associated vascular and target organ damage

Circulating microRNAs implicate multiple atherogenic abnormalities in the long-term cardiovascular sequelae of preeclampsia

Background: Women who have had preeclampsia (PE) are at increased risk for premature cardiovascular disease (CVD). The underlying pathophysiology of this risk remains unclear, but potentially involves subclinical vascular damage or dysfunction. Alterations in the levels of circulating microRNAs may be implicated, as they are known to play pervasive roles in vascular biology. We investigated whether levels of circulating microRNAs are altered between women with premature acute coronary syndrome (ACS), with and without a history of PE. Methods: Women with premature ACS (age ≤ 55 years) were categorized based on a prior history of PE or normotensive pregnancy. Relative plasma levels of 372 microRNAs were initially assessed by polymerase chain reaction array in a subset of subjects (n = 12–13/group) matched for age, chronic hypertension, dyslipidemia, and smoking status. Candidate microRNAs were then validated in a larger cohort of ACS patients (n = 176). Results: MicroRNAs previously linked to angiogenesis (miR-126-3p), inflammation (miR-146a-5p), and cholesterol metabolism (miR-122-5p) were significantly decreased in women with prior PE compared to women with prior normotensive pregnancy (P = 0.002, 0.017, and 0.009, respectively), even after adjustment for chronic hypertension. Conclusions: Circulating levels of miR-126-3p, -146a-5p, and -122-5p were significantly decreased in women with premature ACS who reported prior PE compared to those with prior normotensive pregnancy. These data provide novel insight into potential pathways that may contribute to the increased risk of CVD following PE

Circulating miR-206 and Wnt-signaling are associated with cardiovascular complications and a history of preeclampsia in women

Women with a history of preeclampsia (PE) have increased risk of cardiovascular disease (CVD) later in life. However, the molecular determinants underlying this risk remain unclear. We sought to understand how circulating miRNA levels are impacted by prior PE, and relate to biological pathways underpinning cardiovascular disease. RNA sequencing was used to profile plasma levels of 2578 miRNAs in a retrospective study of women with a history of PE or normotensive pregnancy, in two independent cohorts with either acute coronary syndrome (ACS) (n=17-18/group) or no ACS (n=20/group). Differential miRNA alterations were assessed in relation to a history of PE (within each cohort) or ACS (across cohorts), and compared to miRNAs previously reported to be altered during PE. A history of PE was associated with altered levels of 30 and 20 miRNAs in the ACS and non-ACS cohorts, respectively, whereas ACS exposure was associated with alterations in 259 miRNAs. MiR-206 was identified at the intersection of all comparisons relating to past/current PE and ACS exposure, and has previously been implicated in atherogenic activities related to hepatocytes, vascular smooth muscle cells and macrophages. Integration of all differentially altered miRNAs with their predicted and experimentally-validated targets in silico revealed a number of highly targeted genes with potential atherogenic functions (including NFAT5, CCND2 and SMAD2), and one significantly enriched KEGG biological pathway (Wnt signaling) that was shared between all exposure groups. This study provides novel insights into miRNAs, target genes and biological pathways that may underlie the long term cardiovascular sequelae of PE

Designing and Implementing an Assessment Plan for a Virtual Engineering Lab

This article describes the process of creating, implementing, and assessing an innovative learning tool. The game based laboratory simulation, “Gaming for Applied Materials Engineering” (GAME), incorporated into the Engineering curriculum at a large public university, is intended to facilitate the same learning previously taught in a traditional hands-on laboratory. Through this technological tool, researchers hope to extend an integral learning opportunity to students currently unable to access physical labs, as well as, to augment and reinforce the material taught to those currently enrolled in physical lab courses. Throughout the article, the research team discusses the assessment methodology, describes several challenges overcome, and offers recommendations for others interested in utilizing game-based technology in educational settings.  

Emphysema Is-at the Most-Only a Mild Phenotype in the Sugen/Hypoxia Rat Model of Pulmonary Arterial Hypertension.

Translational research is essential to develop strategies for the treatment of pulmonary arterial hypertension (PAH) using animal models which reproduce the severity, the progressive nature and resistance to treatment of human PAH, including severe arterial remodeling and progressive right ventricular (RV) failure. We read with interest the letter by Kojonazariov et al. who propose to have found “severe emphysema in the SU5416/Hypoxia (SuHx) rat model of pulmonary hypertension”. The authors report that Wistar-Kyoto rats exposed to the combination of VEGFR2 inhibition by SU5416 and chronic hypoxia had moderately increased RVSP and RV mass compared to normoxic untreated animals. They applied in vivo micro-computed tomography (CT) to demonstrate an increase in lung volume and decreased lung density, an unaltered amount of lung tissue, but an increased air-to-tissue ratio, and claim these findings were confirmed by histological analysis, including mean linear intercept as surrogate of emphysema. Indeed, SU5416 has been previously shown to induce emphysema in normoxia, but this required repetitive SU5416 dosing (3 times weekly over 3 weeks) and occurred more predominantly in rats younger than 4 weeks of age (Norbert Voelkel, personal communication). In addition, emphysema could be negated, at the cost of the development of severe angioproliferative hypertension, by concomitant exposure to hypoxia