Corticotropin-releasing hormone as the homeostatic rheostat of feto-maternal symbiosis and developmental programming In utero and neonatal life

A balanced interaction between the homeostatic mechanisms of mother and the devel- oping organism during pregnancy and in early neonatal life is essential in order to ensure optimal fetal development, ability to respond to various external and internal challenges, protection from adverse programming, and safeguard maternal care availability after parturition. In the majority of pregnancies, this relationship is highly effective resulting in successful outcomes. However, in a number of pathological settings, perturbations of the maternal homeostasis disrupt this symbiosis and initiate adaptive responses with unpre- dictable outcomes for the fetus or even the neonate. This may lead to development of pathological phenotypes arising from developmental reprogramming involving interaction of genetic, epigenetic, and environmental-driven pathways, sometimes with acute conse- quences (e.g., growth impairment) and sometimes delayed (e.g., enhanced susceptibility to disease) that last well into adulthood. Most of these adaptive mechanisms are activated and controlled by hormones of the hypothalamo-pituitary adrenal axis under the influ- ence of placental steroid and peptide hormones. In particular, the hypothalamic peptide corticotropin-releasing hormone (CRH) plays a key role in feto-maternal communication by orchestrating and integrating a series of neuroendocrine, immune, metabolic, and behavioral responses. CRH also regulates neural networks involved in maternal behavior and this determines efficiency of maternal care and neonate interactions. This review will summarize our current understanding of CRH actions during the perinatal period, focusing on the physiological roles for both mother and offspring and also how external challenges can alter CRH actions and potentially impact on fetus/neonate health

Effect of sedimentary heterogeneities in the sealing formation on predictive analysis of geological CO₂ storage

Numerical models of geologic carbon sequestration (GCS) in saline aquifers use multiphase fluid flow-characteristic curves (relative permeability and capillary pressure) to represent the interactions of the non-wetting CO2 and the wetting brine. Relative permeability data for many sedimentary formations is very scarce, resulting in the utilisation of mathematical correlations to generate the fluid flow characteristics in these formations. The flow models are essential for the prediction of CO2 storage capacity and trapping mechanisms in the geological media. The observation of pressure dissipation across the storage and sealing formations is relevant for storage capacity and geomechanical analysis during CO2 injection. This paper evaluates the relevance of representing relative permeability variations in the sealing formation when modelling geological CO2 sequestration processes. Here we concentrate on gradational changes in the lower part of the caprock, particularly how they affect pressure evolution within the entire sealing formation when duly represented by relative permeability functions. The results demonstrate the importance of accounting for pore size variations in the mathematical model adopted to generate the characteristic curves for GCS analysis. Gradational changes at the base of the caprock influence the magnitude of pressure that propagates vertically into the caprock from the aquifer, especially at the critical zone (i.e. the region overlying the CO2 plume accumulating at the reservoir-seal interface). A higher degree of overpressure and CO2 storage capacity was observed at the base of caprocks that showed gradation. These results illustrate the need to obtain reliable relative permeability functions for GCS, beyond just permeability and porosity data. The study provides a formative principle for geomechanical simulations that study the possibility of pressure-induced caprock failure during CO2 sequestration

Post-collisional Tertiary–Quaternary mafic alkalic magmatism in the Carpathian–Pannonian region: a review

Mafic alkalic volcanism was widespread in the Carpathian–Pannonian region (CPR) between 11 and 0.2 Ma. It followed the Miocene continental collision of the Alcapa and Tisia blocks with the European plate, as subduction-related calc-alkaline magmatism was waning. Several groups of mafic alkalic rocks from different regions within the CPR have been distinguished on the basis of ages and/or trace-element compositions. Their trace element and Sr–Nd–Pb isotope systematics are consistent with derivation from complex mantle-source regions, which included both depleted asthenosphere and metasomatized lithosphere. The mixing of DMM-HIMU-EMII mantle components within asthenosphere-derived magmas indicates variable contamination of the shallow asthenosphere and/or thermal boundary layer of the lithosphere by a HIMU-like component prior to and following the introduction of subduction components. Various mantle sources have been identified: Lower lithospheric mantle modified by several ancient asthenospheric enrichments (source A); Young asthenospheric plumes with OIB-like trace element signatures that are either isotopically enriched (source B) or variably depleted (source C); Old upper asthenosphere heterogeneously contaminated by DM-HIMU-EMII-EMI components and slightly influenced by Miocene subduction-related enrichment (source D); Old upper asthenosphere heterogeneously contaminated by DM-HIMU-EMII components and significantly influenced by Miocene subduction-related enrichment (source E). Melt generation was initiated either by: (i) finger-like young asthenospheric plumes rising to and heating up the base of the lithosphere (below the Alcapa block), or (ii) decompressional melting of old asthenosphere upwelling to replace any lower lithosphere or heating and melting former subducted slabs (the Tisia block)

Performance of a spin-based insulated gate field effect transistor

Fundamental physical properties limiting the performance of spin field effect transistors are compared to those of ordinary (charge-based) field effect transistors. Instead of raising and lowering a barrier to current flow these spin transistors use static spin-selective barriers and gate control of spin relaxation. The different origins of transistor action lead to distinct size dependences of the power dissipation in these transistors and permit sufficiently small spin-based transistors to surpass the performance of charge-based transistors at room temperature or above. This includes lower threshold voltages, smaller gate capacitances, reduced gate switching energies and smaller source-drain leakage currents.Comment: 4 pages including 3 figures, APL in pres

One-pot multicomponent synthesis of 2,3-dihydropyrans: new access to furanose–pyranose 1,3-C–C-linked-disaccharides

An efficient synthesis of 2,3-dihydropyrans starting from different terminal alkynes was developed. The 2,3-dihydropyrans were obtained in a few minutes through a microwave-assisted multicomponent enyne cross-metathesis/hetero-Diels–Alder reaction. Starting from C-ethynyl-ribofuranose, a new multicomponent approach to furanose–pyranose 1,3-C–C-linked disaccharides was also developed

A wildland fire model with data assimilation

A wildfire model is formulated based on balance equations for energy and fuel, where the fuel loss due to combustion corresponds to the fuel reaction rate. The resulting coupled partial differential equations have coefficients that can be approximated from prior measurements of wildfires. An ensemble Kalman filter technique with regularization is then used to assimilate temperatures measured at selected points into running wildfire simulations. The assimilation technique is able to modify the simulations to track the measurements correctly even if the simulations were started with an erroneous ignition location that is quite far away from the correct one.Comment: 35 pages, 12 figures; minor revision January 2008. Original version available from http://www-math.cudenver.edu/ccm/report

Petrogenesis of lavas from Detroit Seamount: Geochemical differences between Emperor Chain and Hawaiian volcanoes

The Hawaiian Ridge and Emperor Seamount Chain define a hot spot track that provides an 80 Myr record of Hawaiian magmatism. Detroit Seamount (∼76 to 81 Ma) is one of the oldest Emperor Seamounts. Volcanic rocks forming this seamount have been cored by the Ocean Drilling Program at six locations. Only tholeiitic basalt occurs at Site 884 on the eastern flank and only alkalic basalt, probably postshield lavas, occurs at Sites 883 and 1204 on the summit plateau. However, at Site 1203 the basement core (453 m penetration) includes four thick flows of pahoehoe alkalic basalt underlying ∼300 m of volcaniclastic rocks interbedded with submarine erupted tholeiitic basalt. The geochemical characteristics of these alkalic lavas indicate that phlogopite was important in their petrogenesis; they may represent preshield stage volcanism. The surprising upward transition from subaerial to submarine eruptives implies rapid subsidence of the volcano, which can be explained by the inferred near-ridge axis setting of the seamount at ∼80 Ma. A near-ridge axis setting with thin lithosphere is also consistent with a shallow depth of melt segregation for Detroit Seamount magmas relative to Hawaiian magmas, and the significant role for plagioclase fractionation as the Detroit Seamount magmas evolved in the crust. An important long-term trend along the hot spot track is that 87Sr/86Sr decreases in lavas erupted from ∼40 to 80 Ma. Tholeiitic basalt at Site 884 on Detroit Seamount is the extreme and overlaps with the 87Sr/86Sr-143Nd/144Nd field of Pacific mid-ocean ridge basalts (MORB). Complementary evidence for a depleted component in Detroit Seamount lavas is that relative to Hawaiian basalt, Detroit Seamount lavas have lower abundances of incompatible elements at a given MgO content. These lavas, especially from Sites 883 and 884, trend to extremely unradiogenic Pb isotopic ratios which are unlike MORB erupted at the East Pacific Rise. A component with relatively low 87Sr/86Sr and 206Pb/204Pb is required. Lavas erupted from a spreading center in the Garrett transform fault, 13°28′S on the East Pacific Rise, have this characteristic. A plausible hypothesis is mixing of a plume-related component with a component similar to that expressed in lavas from the Garrett transform fault. However, basaltic glasses from Detroit Seamount also have relatively high Ba/Th, a distinctive characteristic of Hawaiian lavas. We argue that all Detroit Seamount lavas, including those from Site 884, are related to the Hawaiian hot spot. Rejuvenated stage Hawaiian lavas also have high Ba/Th and define a trend to low 87Sr/86Sr and 206Pb/204Pb. We speculate that rejuvenated stage lavas and Detroit Seamount lavas sample a depleted mantle component, intrinsic to the plume, over the past 80 Myr