Earth's middle age

This research was funded through Natural Environment Research Council (grant NE/J021822/1) and the APC was paid through the RCUK OA block grant.Earth's middle age, extending from 1.7 to 0.75 Ga, was characterized by environmental, evolutionary, and lithospheric stability that contrasts with the dramatic changes in preceding and succeeding eras. The period is marked by a paucity of preserved passive margins, an absence of a significant Sr anomaly in the paleoseawater record and in the εHf(t) in detrital zircon, a lack of orogenic gold and volcanic-hosted massive sulfide deposits, and an absence of glacial deposits and iron formations. In contrast, anorthosites and kindred bodies are well developed and major pulses of Mo and Cu mineralization, including the world's largest examples of these deposits, are features of this period. These trends are attributed to a relatively stable continental assemblage that was initiated during assembly of the Nuna supercontinent by ca. 1.7 Ga and continued until breakup of its closely related successor, Rodinia, ca. 0.75 Ga. The overall low abundance of passive margins is consistent with a stable continental configuration, which also provided a framework for environmental and evolutionary stability. A series of convergent margin accretionary orogens developed along the edge of the supercontinent. Abundant anorthosites and related rocks developed inboard of the plate margin. Their temporal distribution appears to link with the secular cooling of the mantle, at which time the overlying continental lithosphere was strong enough to be thickened and to support the emplacement of large plutons into the crust, yet the underlying mantle was still warm enough to result in widespread melting of the lower thickened crust.Publisher PDFPeer reviewe

Supernovae astrophysics from Middle Age documents

The supernova explosion of 1054 AD, which originated the Crab Nebula and Pulsar, is probably the astronomical event which has been most deeply studied by means of historical sources. However, many mysteries and inconsistencies, both among the different sources and between what is deduced by the historical records and the present day astronomical data, are demanding extraordinary efforts by theoretical astrophysicists in order to put all the data in a meaningful framework. An accurate analysis of the historical sources, like the one we are presenting here, may contribute to solve some of these problems.Comment: in: Proc. of the IAU Symposium no.230, "Populations of High Energy Sources in Galaxies", held in Dublin (Ireland), August 15-19, 2005. Evert J.A. Meurs & G. Fabbiano, eds. (in press

Middle-Age Job Mobility: Its Determinants and Consequences

Our paper uses the wealth of information available in the NLS to expand on previous work in several ways. First, we investigate whether there is a meaningful distinction among types of job separations. Traditional analysis has categorized job separations as either employee-initiated (quits) or employer-initiated (layoffs). We question whether this dichotomy is correct. The National Longitudinal Survey data is especially useful for studying the relationship between wages and the probability of quitting. Most theoretical work on the determinants of job separation concludes that the probability of changing jobs is related to a reservation wage. The NLS data set allows us to test this relationship since it includes information on the individual's "hypothetical wage"-- that is, the wage required to induce the individual to accept another job. Given this information, we are able to compare the effects of different measures of the individual's price of time (e.g. the current wage and the reservation wage) on the probability of quitting. In addition, we analyze the role of human capital variables, job related characteristics and family background in the determination of job mobility. The analysis of the determinants of job separations in the cross-section naturally leads to an investigation of the relationship between previous separations and future separations. In particular, we consider whether such a relationship exists, and whether the nature of previous separations is a good predictor of the nature of future separations. Finally, we analyze the effects of job mobility on earnings and on job satisfaction. We distinguish between the immediate gains to mobility and the future gains to mobility, and also consider whether the nature of the separation is an important determinant of the consequences of job mobility.

Psychosocial factors influencing risk-taking in middle age for STIs

Objectives To increase the knowledge of the psychosocial factors influencing sexual risk-taking for STIs among adults in late middle age. Methods Individual interviews were conducted either face to face or by telephone with 31 heterosexual men and women aged between 45 and 65. They were recruited from NHS sexual health services (n=16) and council run culture and leisure facilities (n=15) in a large Scottish city. A total of 18 women and 13 men were interviewed. All interviews were transcribed in full and thematically analysed. Results Analysis detailed important psychosocial and sociocultural factors; the prioritisation of intimacy above and beyond concerns about risks for STI in sexual partnerships; the importance of unwanted pregnancy in shaping risk perceptions throughout the life course; vulnerability associated with periods of relationship transition (eg, bereavement, divorce or separation); social norms and cultural expectations relating to age-appropriate sexual and health-seeking behaviours. Conclusions This is the first qualitative study to examine the factors associated with sexual risk-taking among heterosexual adults in late middle age in the UK. Many factors associated with sexual risk-taking are similar to those reported within other populations. However, we also detail population-specific factors, which should be considered in terms of the development of interventions for ‘at risk’ older adults, or the tailoring of wider behaviour change interventions to this specific age group

"The Persistence of Hardship Over the Life Course"

This paper focuses on the persistence of hardship from middle age to old age. Proposed status maintenance models suggest that stratification of economic status occurs over the life course (e.g., little mobility is seen within the income distribution). Some studies have found evidence to support this, but none have looked at broader measures of well-being. Using 29 years (1968-96) of data from the Panel Study of Income Dynamics (PSID), the author employs hypothesis tests (t-tests) and logistic regression techniques to examine the relationship between middle-age chronic hardships and adverse old-age outcomes. In almost every case, individuals who experience middle-age chronic hardships are significantly (statistically) more likely to experience adverse old-age outcomes.

思春期の子どもを持つ母親のアイデンティティと親子関係

本研究は、岡本(1996) の育児期の女性のアイデンティティ様態の捉え方をモデルとして、思春期の子どもを持つ中年期の母親のアイデンティティ様態を、個としてのアイデンティティの達成と母性意識の確立という2つの次元から捉え、アイデンティティ様態と親子関係について検討することを目的とした。150人の母親に質問紙調査を行い(有効回答69)、個としてのアイデンティティ達成度と母性意識の高さにより、統合型、伝統的母親型、独立的母親型、未熟型の4つのタイプに分類し分析した結果、伝統的母親型や統合型の母親は、「子どもへの献身と密着」の感情が高く、独立的母親型の母親は、「子どもの成長に対する寂しさ」の感情が低いことが分かつた。4つのアイデンティティ様態別に17人の母親に個別に面接を行った結果、アイデンティティ様態によって著しい相違がみられた。統合型の母親は、不安や葛藤を抱えながらも思春期の子どもと積極的に係わっており、伝統的母親型や未熟型の母親は、子どもとの問に不安や葛藤が多く、特に未熟型の母親は、自分自身への不満もみられた。一方、独立的母親型の母親は、子どもとの間に不安や葛藤はあまりなく、互いに独立性を認めていることが伺われた

Second Age, Middle Age

The recent releases of the volume The Fall of Númenor and the series The Lord of the Rings: The Rings of Power raise the question: What is the significance of the Second Age of Tolkien’s legendarium? This article suggests that Tolkien conceived of the Second Age as parallel to the Middle Ages in our world, which were the focus of his academic career in his studies of Old and Middle English language and literature. As various frameworks and overviews for the legendarium demonstrate, Tolkien thought of the Second Age, like the Middle Ages, as uniquely looking backwards and forwards in time. At the same time, the incomplete and fragmentary nature of the stories from the Second Age—in the appendices to The Lord of the Rings, The Silmarillion, Unfinished Tales, and various volumes of The History of Middle-Earth—shows that Tolkien was unsuccessful in creating a center and meaning to his legendarium. Instead of creating hope for improvement, they ultimately always exposed the corruption, decay, decline, and failure at the center of the human experience

Predicting invasive breast cancer versus DCIS in different age groups.

BackgroundIncreasing focus on potentially unnecessary diagnosis and treatment of certain breast cancers prompted our investigation of whether clinical and mammographic features predictive of invasive breast cancer versus ductal carcinoma in situ (DCIS) differ by age.MethodsWe analyzed 1,475 malignant breast biopsies, 1,063 invasive and 412 DCIS, from 35,871 prospectively collected consecutive diagnostic mammograms interpreted at University of California, San Francisco between 1/6/1997 and 6/29/2007. We constructed three logistic regression models to predict the probability of invasive cancer versus DCIS for the following groups: women ≥ 65 (older group), women 50-64 (middle age group), and women < 50 (younger group). We identified significant predictors and measured the performance in all models using area under the receiver operating characteristic curve (AUC).ResultsThe models for older and the middle age groups performed significantly better than the model for younger group (AUC = 0.848 vs, 0.778; p = 0.049 and AUC = 0.851 vs, 0.778; p = 0.022, respectively). Palpability and principal mammographic finding were significant predictors in distinguishing invasive from DCIS in all age groups. Family history of breast cancer, mass shape and mass margins were significant positive predictors of invasive cancer in the older group whereas calcification distribution was a negative predictor of invasive cancer (i.e. predicted DCIS). In the middle age group--mass margins, and in the younger group--mass size were positive predictors of invasive cancer.ConclusionsClinical and mammographic finding features predict invasive breast cancer versus DCIS better in older women than younger women. Specific predictive variables differ based on age