Ages for exoplanet host stars

Age is an important characteristic of a planetary system, but also one that is difficult to determine. Assuming that the host star and the planets are formed at the same time, the challenge is to determine the stellar age. Asteroseismology provides precise age determination, but in many cases the required detailed pulsation observations are not available. Here we concentrate on other techniques, which may have broader applicability but also serious limitations. Further development of this area requires improvements in our understanding of the evolution of stars and their age-dependent characteristics, combined with observations that allow reliable calibration of the various techniques.Comment: To appear in "Handbook of Exoplanets", eds. Deeg, H.J. & Belmonte, J.A, Springer (2018

Targeted sequencing to identify novel genetic risk factors for deep vein thrombosis: a study of 734 genes

Essentials Deep vein thrombosis (DVT) has a large unknown genetic component. We sequenced coding areas of 734 hemostasis-related genes in 899 DVT patients and 599 controls. Variants in F5, FGA-FGG, CYP4V2-KLKB1-F11, and ABO were associated with DVT risk. Associations in KLKB1 and F5 suggest a more complex genetic architecture than previously thought. Summary: Background Although several genetic risk factors for deep vein thrombosis (DVT) are known, almost all related to hemostasis, a large genetic component remains unexplained. Objectives To identify novel genetic determinants by using targeted DNA sequencing. Patients/Methods We included 899 DVT patients and 599 controls from three case\u2013control studies (DVT-Milan, Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis [MEGA], and the Thrombophilia, Hypercoagulability and Environmental Risks in Venous Thromboembolism [THE-VTE] study) for sequencing of the coding regions of 734 genes involved in hemostasis or related pathways. We performed single-variant association tests for common variants (minor allele frequency [MAF] 65 1%) and gene-based tests for rare variants (MAF 64 1%), accounting for multiple testing by use of the false discovery rate (FDR). Results Sixty-two of 3617 common variants were associated with DVT risk (FDR 0.2). Conclusions We confirmed associations between DVT and common variants in F5,ABO,FGA\u2013FGG, and CYP4V2\u2013KLKB1\u2013F11, and observed secondary signals in F5 and CYP4V2\u2013KLKB1\u2013F11 that warrant replication and fine-mapping in larger studies

バレイショ近縁種における種の分化 XIII. S.acaule X S.demissumより得た7倍雑種の染色体行動と両親ゲノムの類縁関係

中央アンデス産Acaulia群4倍種S. acaule (acl, 2n=48)とメキシコ産Demissa群6倍種S. demissum (dms, 2n=72)のゲノムの類縁関係を明らかにするために, 前者を母本として得た7倍雑種(2n=84)の還元分裂における染色体行動と稔性を調べた。以下その結果を要約する。両種間の交雑は極めて困難で, aclを母とした時のみ受粉花数当り0.02の低率で雑種が得られたにすぎない。得られた雑種は, 両親との形態的比較から, aclの非還元性卵とdmsの還元性花粉の受精に起因するものと推定された。この雑種の第1中期における染色体対合行動は甚だしく多様であったが, その対合型のモードは(12)_+(20)_+8_I, その平均対合頻度は(0.18)_V+(1.11)_+(11.73)_+(18.11)_+(7.26)_Iで, 著しく高頻度の3価形成を示す点が特徴的であった。このような対合行動はその後の染色体行動にも反映し, 第1後期では観察細胞のすべてに平均4.8の遅滞染色体がみられ, 第2中期では94%の細胞が分散染色体を示し, 数的平衡核板頻度は0.6%にすぎなかった。稔性は極めて低く, 調査花粉粒数の27%が一見正常であったが, 自殖及び戻交配のいずれにおいても全く種子を生じなかった。上記の観察結果, 特に高頻度で出現した3価染色体の成因を考察して次の知見を得た。すでにaclはAAA^aA^a, dmsはA^dA^dC_1C_1C_2C_2のゲノム型をもつことが知られているので, 当雑種のゲノム型はAAA^aA^aA^dC_1C_2となる。A^dゲノムは若干の構造的差異はもつもののAゲノム群に属することも知られている。したがって, 当雑種にみられる3価形成は, 主に, aclからのAAとdmsからのA^dの3ゲノム間の染色体対合に由来すると推論でき, 両種はこれらのゲノムの相同性によって相互に関係づけられているものと考えられる。 / Meiotic behavior and fertility were studied in a heptaploid F_1 hybrid (2n=84) obtained from crossing S. acaule (acl, 2n=48) with S. demissum (dms, 2n=72), with the aim of assessing a genomic relationship between the parent species. Crossability between the two species was very low, the number of hybrid plants per pollination being only 0.02. Morphological evidence indicated that the hybrid arose through the union of an unreduced egg of acl and a reduced pollen grain of dms. The hybrid had the mean pairing frequency of (0.18)_V+(1.11)_+(11.73)_+(18.11)_+(7.26)_I per cell at metaphase I, with (12)_+(20)_+8_I as the modal configuration. Its subsequent behaviors were extremely irregular, showing several laggards in all the cells and chromatid bridges in occasional cells at anaphase I and also scattered chromosomes in 94% of the cells at metaphase II. The hybrid gave only 27% stainable pollen and no seed either on selfing or on backcrossing with both parents. The pattern of chromosome pairing found in the hybrid was interpreted in terms of genomic relationship between both parent species. From this, it was suggested that one (A) of the two genomes (designated AA^a) which acl possess in its gametes seems to be closely similar to, but not identical with, one (A^d) of the three genomes (A^dC_1C_2) which dms possess in its gemetes

Optimal cutoff values for high-risk waist circumference in older adults based on related health outcomes.

The authors aimed to explore optimal cutoffs for high-risk waist circumference (WC) in older adults to assess the health risks of obesity. Prospective data from 4,996 measurements in 2,232 participants aged ≥70 years were collected during 5 triennial measurement cycles (1992/1993-2005/2006) of a population-based cohort study, the Longitudinal Aging Study Amsterdam (Amsterdam, the Netherlands). Cross-sectional associations of WC with pain, mobility limitations, incontinence, knee osteoarthritis, cardiovascular disease, and diabetes were studied. Generalized estimating equations models were fitted with restricted cubic spline functions in order to carefully study the shapes of the associations. Model fits for applying different cutoffs to categorize WC in the association with all outcomes were tested using the quasi-likelihood under the Independence Criterion (QIC). On the basis of the spline regression curves, potential WC cutoffs of approximately 109 cm in men and 98 cm in women were proposed. Based on the model fit, cutoffs between 100 cm and 106 cm were equally applicable in men but should not be higher. In women, the QIC confirmed an optimal cutoff of 99 cm