Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation

We apply hydrodynamic evaporation models to different synthetic planet populations that were obtained from a planet formation code based on a core-accretion paradigm. We investigated the evolution of the planet populations using several evaporation models, which are distinguished by the driving force of the escape flow (X-ray or EUV), the heating efficiency in energy-limited evaporation regimes, or both. Although the mass distribution of the planet populations is barely affected by evaporation, the radius distribution clearly shows a break at approximately 2 $R_{\oplus}$. We find that evaporation can lead to a bimodal distribution of planetary sizes (Owen & Wu 2013) and to an "evaporation valley" running diagonally downwards in the orbital distance - planetary radius plane, separating bare cores from low-mass planet that have kept some primordial H/He. Furthermore, this bimodal distribution is related to the initial characteristics of the planetary populations because low-mass planetary cores can only accrete small primordial H/He envelopes and their envelope masses are proportional to their core masses. We also find that the population-wide effect of evaporation is not sensitive to the heating efficiency of energy-limited description. However, in two extreme cases, namely without evaporation or with a 100\% heating efficiency in an evaporation model, the final size distributions show significant differences; these two scenarios can be ruled out from the size distribution of $Kepler$ candidates.Comment: Accepted for publication in ApJ; 24 pages, 16 figure

Toward an Optimal Online Checkpoint Solution under a Two-Level HPC Checkpoint Model

The traditional single-level checkpointing method suffers from significantoverhead on large-scale platforms. Hence, multilevel checkpointing protocols have been studied extensively in recent years. The multilevel checkpoint approach allows different levels of checkpoints to be set (each with different checkpoint overheads and recovery abilities), in order to further improve the fault tolerance performance of extreme-scale HPC applications. How to optimize the checkpoint intervals for each level, however, is an extremely difficult problem. In this paper, we construct an easy-to-use two-level checkpoint model. Checkpoint level 1 deals with errors with low checkpoint/recovery overheads such as transient memory errors, while checkpoint level 2 deals with hardware crashes such as node failures.Compared with previous optimization work, our new optimal checkpoint solution offers two improvements: (1) it is an online solution without requiring knowledge of the job length in advance, and (2) it shows that periodic patterns are optimal and determines the best pattern. We evaluate the proposed solution and compare it with the most up-to-date related approaches on an extreme-scale simulation testbed constructed based on a real HPC application execution. Simulation results show that our proposed solution outperforms other optimized solutions and can improve the performance significantly in some cases. Specifically, with the new solution the wall-clock time can be reduced by up to 25.3\% over that of other state-of-the-art approaches. Finally, a brute-force comparison with all possible patterns shows that our solution is always within $1\%$ of the best pattern in the experiments

ROS from menadione induces astrocytic damage: protective effects of apocynin

Abstract only availableOxidative stress is a core cause of neurodegenerative diseases such as Alzheimer's disease. When cells are under oxidative stress, they will produce a high amount of reactive oxygen species (ROS). ROS are small and highly reactive and include compounds such as oxygen ions, free radicals, and peroxides. Understanding what triggers oxidative stress and how to ameliorate its damaging effects is a crucial step in discovering a cure for Alzheimer's disease. Menadione, a vitamin precursor of K2, is an oxidative compound that is capable of delivering ROS to the cells. Apocynin, a natural organic compound that has been isolated from Picrorhiza curroa grown in the Himalayan Mountains, is an inhibitor of NADPH oxidase, an enzyme for ROS production in cells. In this experiment, we studied whether apocynin may neutralize the effects of menadione using an immortalized astrocyte cell line DITNC. Astrocytes are glial cells that play a crucial role in the brain by providing necessary nutrient to surrounding neurons. We had three sample groups and treated each group with different drugs. The first group was the control, the second group was treated with menadione, and the third group was treated with both menadione and apocynin. After treating the cells, we recorded morphological changes of the cells by taking pictures of each sample group at three different time intervals (30 min, 1 and 2 hours). In addition to the morphological evidence, we also did a MTT assay to assess cell viability and later a data analysis based on the result from the MTT test. MTT assay measures mitochondrial activity and thus indirectly measures cell viability. Both morphological data and MTT analysis showed menadione caused DITNC cell damage with decreased mitochondrial activity. When cells are treated with menadione, they formed processes, shrink, and then round up. We also found apocynin protects against the oxidative damage caused by menadione to a certain extent. Since apocynin is an inhibitor of NADPH oxidase, this also indicates oxidative stress is generated by NADPH oxidase, suggesting apocynin may be a potential means to treat Alzheimer's disease.Alzheimer disease program project grant 2P01 AG018357 to G. Su

The ability of pandemic influenza virus hemagglutinins to induce lower respiratory pathology is associated with decreased surfactant protein D binding

AbstractPandemic influenza viral infections have been associated with viral pneumonia. Chimeric influenza viruses with the hemagglutinin segment of the 1918, 1957, 1968, or 2009 pandemic influenza viruses in the context of a seasonal H1N1 influenza genome were constructed to analyze the role of hemagglutinin (HA) in pathogenesis and cell tropism in a mouse model. We also explored whether there was an association between the ability of lung surfactant protein D (SP-D) to bind to the HA and the ability of the corresponding chimeric virus to infect bronchiolar and alveolar epithelial cells of the lower respiratory tract. Viruses expressing the hemagglutinin of pandemic viruses were associated with significant pathology in the lower respiratory tract, including acute inflammation, and showed low binding activity for SP-D. In contrast, the virus expressing the HA of a seasonal influenza strain induced only mild disease with little lung pathology in infected mice and exhibited strong in vitro binding to SP-D

Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S=1 quantum antiferromagnet

The magnetic ground state of the quasi-one-dimensional spin-1 antiferromagnetic chain is sensitive to the relative sizes of the single-ion anisotropy (D) and the intrachain (J) and interchain (J') exchange interactions. The ratios D/J and J'/J dictate the material's placement in one of three competing phases: a Haldane gapped phase, a quantum paramagnet and an XY-ordered state, with a quantum critical point at their junction. We have identified [Ni(HF)2(pyz)_2]SbF6, where pyz = pyrazine, as a rare candidate in which this behavior can be explored in detail. Combining neutron scattering (elastic and inelastic) in applied magnetic fields of up to 10~tesla and magnetization measurements in fields of up to 60~tesla with numerical modeling of experimental observables, we are able to obtain accurate values of all of the parameters of the Hamiltonian [D = 13.3(1)~K, J = 10.4(3)~K and J' = 1.4(2)~K], despite the polycrystalline nature of the sample. Density-functional theory calculations result in similar couplings (J = 9.2~K, J' = 1.8~K) and predict that the majority of the total spin population resides on the Ni(II) ion, while the remaining spin density is delocalized over both ligand types. The general procedures outlined in this paper permit phase boundaries and quantum-critical points to be explored in anisotropic systems for which single crystals are as yet unavailable

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) : A Hot Corino Survey toward Protostellar Cores in the Orion Cloud

The presence of complex organic molecules (COMs) in the interstellar medium is of great interest since it may link to the origin and prevalence of life in the universe. Aiming to investigate the occurrence of COMs and their possible origins, we conducted a chemical census toward a sample of protostellar cores as part of the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps project. We report the detection of 11 hot corino sources, which exhibit compact emissions from warm and abundant COMs, among 56 Class 0/I protostellar cores. All of the hot corino sources discovered are likely Class 0, and their sizes of the warm region (>100 K) are comparable to 100 au. The luminosity of the hot corino sources exhibits positive correlations with the total number of methanol and the extent of its emissions. Such correlations are consistent with the thermal desorption picture for the presence of hot corinos and suggest that the lower-luminosity (Class 0) sources likely have a smaller region with COM emissions. With the same sample selection method and detection criteria being applied, the detection rates of the warm methanol in the Orion cloud (15/37) and the Perseus cloud (28/50) are statistically similar when the cloud distances and the limited sample size are considered. Observing the same set of COM transitions will bring a more informative comparison between the cloud properties.Peer reviewe

Women and leadership in higher education in China: discourse and the discursive construction of identity

Prior research indicates that just 4.5 percent of mainland China’s higher educational institution leaders are female. This article extends theory and research by drawing attention to identity and Discourse as an important, yet under-researched, aspect of the problem of women’s underrepresentation in higher education leadership. Drawing on in-depth qualitative interviews with nine female academics in Chinese universities and informed by discursive approaches to identity and constructionist views, we analyze how women construct multiple identities, the interplay of identities, and the influence of broader societal Discourses of gender and leadership. The findings highlight the interplay between competing multiple identities, and illustrate how the women’s identities are shaped and constrained by dominant historical and cultural Discourses in Chinese society, which results in identity regulation (Alvesson and Billing 2009), notably identity positioning that is congruent with social norms and conventions. A key finding is that the female academics reject the leader identity. This is true for those in middle management positions, as well as women in early career stages, who might otherwise aspire to leadership. Implications for the leadership pipeline in China’s universities is discussed and recommendations are made for future research directions

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP). I. Detection of New Hot Corinos with the ACA

We report the detection of four new hot corino sources, G211.47-19.27S, G208.68-19.20N1, G210.49-19.79W, and G192.12-11.10, from a survey study of Planck Galactic Cold Clumps in the Orion Molecular Cloud Complex with the Atacama Compact Array. Three sources had been identified as low-mass Class 0 protostars in the Herschel Orion Protostar Survey. One source in the lambda Orionis region is first reported as a protostellar core. We have observed abundant complex organic molecules (COMs), primarily methanol but also other oxygen-bearing COMs (in G211.47-19.27S and G208.68-19.20N1) and the molecule of prebiotic interest NH2CHO (in G211.47-19.27S), signifying the presence of hot corinos. While our spatial resolution is not sufficient to resolve most of the molecular emission structure, the large line width and high rotational temperature of COMs suggest that they likely reside in the hotter and innermost region immediately surrounding the protostar. In G211.47-19.27S, the D/H ratio of methanol ([CH2DOH]/[CH3OH]) and the(12)C/C-13 ratio of methanol ([CH3OH]/[(CH3OH)-C-13]) are comparable to those of other hot corinos. Hydrocarbons and long-carbon-chain molecules such as c-C(3)H(2)and HCCCN are also detected in the four sources, likely tracing the outer and cooler molecular envelopes.Peer reviewe