Indosinian high-strain deformation for the Yunkaidashan tectonic belt, south China : Kinematics and 40Ar/39Ar geochronological constraints

Structural and 40Ar/39Ar data from the Yunkaidashan Belt document kinematic and tectonothermal characteristics of early Mesozoic Indosinian orogenesis in the southern part of the South China Block. The Yunkaidashan Belt is tectonically divided from east to west into the Wuchuang-Sihui shear zone, Xinyi-Gaozhou block, and the Fengshan-Qinxi shear zone. Indosinian structural elements ascribed to the Indosinian orogeny include D2 and D3 deformation. The early D2 phase is characterized by folding and thrusting with associated foliation and lineation development, related to NW-SE transpression under amphibolite- to greenschist-facies conditions. This event is heterogeneously overprinted by D3 deformation characterized by a gentle-dipping S-3 foliation, subhorizontally to shallowly plunging L3 lineation, some reactived-D2 folds and low-angle normal faults. The D3 fabrics suggest a sinistral transtensional regime under greenschist-facies metamorphism. The timing of the D2 and D3 events have been constrained to the early to middle Triassic (similar to 248-220 Ma) and late Triassic (similar to 220-200 Ma) respectively on the basis of 40Ar/39Ar geochronology and regional geological relations. The change from oblique thrusting (D2) to sinistral transtension (D3) may reflect oblique convergence and crustal thickening followed by relaxation of the overthickened crust. In combination with the regional relations from Xuefengshan to Yunkaidashan and on to Wuyishan, the early phase of the Indosinian orogeny constituted a large-scale positive flower structure and is related to the intracontinental convergence during the assembly of Pangea in which the less competent South China Orogen was squeezed between the more competent North China and Indosinian Blocks.Peer reviewe

Analyzing Childlessness

Childlessness has been on the rise in many European societies. In Germany, the UK, Austria, the Netherlands, and Switzerland, childlessness has increased starting with the 1950s cohorts. In these countries, about 20 % of the women born around 1965 will remain childless. In southern Europe and the former state-socialist countries of Central and Eastern Europe, the rise in levels of childlessness is a more recent phenomenon. Yet among younger cohorts in these countries, childlessness has reached levels of 15 % or higher. In this introductory chapter, we summarize the long-term trends in childlessness and discuss the differences between European countries in the prevalence of childlessness. We also outline the structure and the logic of this volume

African ancestry of New World, Bemisia tabaci-whitefly species

Bemisia tabaci whitefly species are some of the world’s most devastating agricultural pests and plant-virus disease vectors. Elucidation of the phylogenetic relationships in the group is the basis for understanding their evolution, biogeography, gene-functions and development of novel control technologies. We report here the discovery of five new Sub-Saharan Africa (SSA) B. tabaci putative species, using the partial mitochondrial cytochrome oxidase 1 gene: SSA9, SSA10, SSA11, SSA12 and SSA13. Two of them, SSA10 and SSA11 clustered with the New World species and shared 84.8‒86.5% sequence identities. SSA10 and SSA11 provide new evidence for a close evolutionary link between the Old and New World species. Re-analysis of the evolutionary history of B. tabaci species group indicates that the new African species (SSA10 and SSA11) diverged from the New World clade c. 25 million years ago. The new putative species enable us to: (i) re-evaluate current models of B. tabaci evolution, (ii) recognise increased diversity within this cryptic species group and (iii) re-estimate divergence dates in evolutionary time

Environmental factors, epigenetics, and developmental origin of reproductive disorders

Sex-specific differentiation, development, and function of the reproductive system are largely dependent on steroid hormones. For this reason, developmental exposure to estrogenic and anti-androgenic endocrine disrupting chemicals (EDCs) is associated with reproductive dysfunction in adulthood. Human data in support of “Developmental Origins of Health and Disease” (DOHaD) comes from multigenerational studies on offspring of diethylstilbestrol-exposed mothers/grandmothers. Animal data indicate that ovarian reserve, female cycling, adult uterine abnormalities, sperm quality, prostate disease, and mating behavior are susceptible to DOHaD effects induced by EDCs such as bisphenol A, genistein, diethylstilbestrol, p,p′-dichlorodiphenyl-dichloroethylene, phthalates, and polyaromatic hydrocarbons. Mechanisms underlying these EDC effects include direct mimicry of sex steroids or morphogens and interference with epigenomic sculpting during cell and tissue differentiation. Exposure to EDCs is associated with abnormal DNA methylation and other epigenetic modifications, as well as altered expression of genes important for development and function of reproductive tissues. Here we review the literature exploring the connections between developmental exposure to EDCs and adult reproductive dysfunction, and the mechanisms underlying these effects

“Never Say Never?”: Heterosexual, bisexual, and lesbian women’s accounts of being childfree

Feminist scholars have identified a “motherhood imperative” in Western cultures, where heterosexual women are understood to both want, and have, children. However, social shifts have resulted in a decrease in pronatalism as well as an increase in social recognition of the parenting desires of same-sex parents. Despite a resurgence of interest in childfree identities, research to date has predominantly focused on heterosexual women’s explanations for being childfree and their experiences of marginalisation. Our aim in the current study was to explore how childfree heterosexual, lesbian, bisexual, and queer women negotiate their childfree lives and identities in the context of their personal and social relationships within changing cultural contexts. Data from 23 interviews with women in the United Kingdom, who responded to a call for childfree participants, were thematically analysed. We constructed two themes: 1) Never say never? Negotiating being childfree as ever precarious, shows how women constructed being childfree as requiring constant revisiting and renegotiating to maintain; 2) An ordinary life: Constructing being childfree as rational and reasonable, in which we identify the rhetorical efforts of participants to establish their being childfree as an ordinary, reasonable, and rational position. We conclude that for these women, childfreedom was constantly in flux and that maintaining a positive childfree identity required considerable identity work in order to manage intimate personal relationships and wider friendships

Early Jurassic palaeoenvironments in the Surat Basin, Australia - marine incursion into eastern Gondwana

Interpretations of palaeodepositional environments are important for reconstructing Earth history. Only a few maps showing the Jurassic depositional environments in eastern Australia currently exist. Consequently, a detailed understanding of the setting of Australia in Gondwana is lacking. Core, wireline logs, two‐dimensional and three‐dimensional seismic from the Precipice Sandstone and Evergreen Formation in the Surat Basin have been used to construct maps showing the evolution of depositional environments through the Early Jurassic. The results indicate the succession consists of three third‐order sequences (Sequence 1 to Sequence 3) that were controlled by eustatic sea level. The lowstand systems tract in Sequence 1 comprises braidplain deposits, confined to a fairway that parallels the basin centre. The strata were initially deposited in two sub‐basins, with rivers flowing in different orientations in each sub‐basin. The transgressive systems tract of Sequence 1 to lowstand systems tract of Sequence 3 is dominated by fluvio–deltaic systems infilling a single merged basin centre. Finally, the transgressive and highstand systems tracts of Sequence 3 show nearshore environments depositing sediment into a shallow marine basin. In the youngest part of this interval, ironstone shoals are the most conspicuous facies, the thickness and number of which increase towards the north and east. This study interprets a corridor to the open ocean through the Clarence–Moreton Basin, or the Carpentaria and Papuan basins, evidence of which has been eroded. These results challenge a commonly held view that eastern Australia was not influenced by eustasy, and propose a more dynamic palaeogeographic setting comprising a mixture of fluvial, deltaic and shallow marine sedimentary environments. This work can be used to unravel the stratigraphic relationships between Mesozoic eastern Australian basins, or in other basins globally as an analogue for understanding the complex interplay of paralic depositional systems in data poor areas

The planform of epeirogeny: vertical motions of Australia during the Cretaceous

Estimates of dynamic motion of Australia since the end of the Jurassic have been made by modeling marine flooding and comparing it with palaeogeographical reconstructions of marine inundation. First, sediment isopachs were back stripped from present-day topography. Dynamic motion was determined by the displacement needed to approximate observed flooding when allowance is made for changes in eustatic sea-level. The reconstructed inundation patterns suggest that during the Cretaceous, Australia remained a relatively stable platform, and flooding in the eastern interior during the Early Cretaceous was primarily the result of the regional tectonic motion. Vertical motion during the Cretaceous was much smaller than the movement since the end of the Cretaceous. Subsidence and marine flooding in the Eromanga and Surat Basins, and the subsequent 500 m of uplift of the eastern portion of the basin, may have been driven by changes in plate dynamics during the Mesozoic. Convergence along the north-east edge of Australia between 200 and 100 Ma coincides with platform sedimentation and subsidence within the Eromanga and Surat Basins. A major shift in the position of subduction at 140 Ma was coeval with the marine incursion into the Eromanga. When subduction ended at 95 Ma, marine inundation of the Eromanga also ended. Subsidence and uplift of the eastern interior is consistent with dynamic models of subduction in which subsidence is generated when the dip angle of the slab decreases and uplift is generated when subduction terminates (i.e. the dynamic load vanishes). Since the end of the Cretaceous, Australia has uniformly subsided by about 250 m with little apparent tilting. This vertical subsidence may have resulted from the northward migration of the continent from a dynamic topography high and geoid low toward lower dynamic topography and a higher geoid.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71983/1/j.1365-2117.1994.tb00076.x.pd

Multiple Motherhoods: The Effect of the Internalization of Motherhood Ideals on Life Satisfaction

Purpose – This study examined whether life satisfaction varied among women who occupy different motherhood statuses, and if these variations were influenced by differences in women’s internalization of cultural motherhood norms. We distinguished among women as biological mothers, stepmothers, and “double mothers,” who were both biological and stepmothers. We also included two groups of women without children: voluntary childfree and involuntary childless women. Design/methodology/approach – Data were drawn from the National Study of Fertility Barriers and analyzed using OLS regression. Findings – Biological mothers reported greater life satisfaction than women in other motherhood statuses. Accounting for the internalization of motherhood norms, double mothers had significantly lower life satisfaction compared to biological mothers, but voluntary childfree women had significantly greater life satisfaction. More detailed analyses indicated that internalization of cultural norms only appears to influence the life satisfaction of women with biological children. Research limitations/implications – The results suggest that it may not simply be motherhood that affects women’s well-being, but rather that women’s internalization of motherhood ideals, particularly when it corresponds with their motherhood status, significantly impacts well-being. Limitations of this study include small cell sizes for some categories of women where additional distinctions may have been useful, such as lesbian or adoptive mothers. Future work should incorporate diverse family forms and expand on the newly named category “double mothers.” Originality/value – By providing a more nuanced approach to categorizing motherhood status, including identifying double mothers, stepmothers-only, and two groups of childless women, the study added detail that has been overlooked in previous work on well-being

Growth Dynamics of Australia's Polar Dinosaurs

Analysis of bone microstructure in ornithopod and theropod dinosaurs from Victoria, Australia, documents ontogenetic changes, providing insight into the dinosaurs' successful habitation of Cretaceous Antarctic environments. Woven-fibered bone tissue in the smallest specimens indicates rapid growth rates during early ontogeny. Later ontogeny is marked by parallel-fibered tissue, suggesting reduced growth rates approaching skeletal maturity. Bone microstructure similarities between the ornithopods and theropods, including the presence of LAGs in each group, suggest there is no osteohistologic evidence supporting the hypothesis that polar theropods hibernated seasonally. Results instead suggest high-latitude dinosaurs had growth trajectories similar to their lower-latitude relatives and thus, rapid early ontogenetic growth and the cyclical suspensions of growth inherent in the theropod and ornithopod lineages enabled them to successfully exploit polar regions