Sound velocities of cementite Fe3C have been measured up to 1.5 Mbar and at 300 K in a diamond anvil cell using the nuclear resonant inelastic X-ray scattering (NRIXS) technique. From the partial phonon density of states (pDOS) and equation of state (EOS) of Fe3C, we derived its elastic parameters including shear modulus, compressional (V-p) and shear-wave (V-s) velocities to core pressures. A pressure-induced spin-pairing transition in the powdered Fe3C sample was found to occur gradually between 10 and 50 GPa by the X-ray Emission Spectroscopy (XES) measurements. Following the completion of the spin-pairing transition, the V-p and V-s of low-spin Fe3C increased with pressure at a markedly lower rate than its high-spin counterpart. Our results suggest that the incorporation of carbon in solid iron to form iron carbide phases, Fe3C and Fe7C3, could effectively lower the V-s but respectively raise the Poisson's ratio by 0.05 and 0.07 to approach the seismically observed values for the Earth's inner core. The comparison with the preliminary reference Earth model (PREM) implies that an inner core composition containing iron and its carbon-rich alloys can satisfactorily explain the observed seismic properties of the inner core. (C) 2018 Elsevier B.V. All rights reserved.

Much effort has been devoted to understand how chromatin modification regulates development and disease. Despite recent progress, however, it remains difficult to obtain high-quality epigenomic maps using chromatin-immunoprecipitation-coupled deep sequencing (ChIP-seq) in samples with low-cell numbers. Here, we present an Atlantis dsDNase-based technology, aFARP-ChIP-seq, that provides accurate profiling of genome-wide histone modifications in as few as 100 cells. By mapping histone lysine trimethylation (H3K4me3) and acetylation (H3K27Ac) in group I innate lymphoid cells (ILC1) sorted from different tissues in parallel, aFARP-ChIP-seq uncovers putative active promoter and enhancer landscapes of several tissue-specific Natural Killer cells (NK) and ILC1. aFARP-ChIP-seq is also highly effective in mapping transcription factor binding sites in small number of cells. Thus, aFARP-ChIP-seq offers multiplexing mapping of both epigenome and transcription factor binding sites using a small number of cells.

Supernova (SN) 2017cbv in NGC 5643 is one of a handful of Type Ia supernovae (SNe Ia) reported to have excess blue emission at early times. This paper presents extensive BVRIYJHK(s)-band light curves of SN 2017cbv, covering the phase from -16 to +125 days relative to B-band maximum light. The SN 2017cbv reached a B-band maximum of 11.710 0.006 mag, with a postmaximum magnitude decline of Delta m(15)(B) = 0.990 0.013 mag. The SN suffered no host reddening based on Phillips intrinsic color, the Lira-Phillips relation, and the CMAGIC diagram. By employing the CMAGIC distance modulus mu = 30.58 0.05 mag and assuming H-0 = 72 km s(-1) Mpc(-1), we found that 0.73 M Ni-56 was synthesized during the explosion of SN 2017cbv, which is consistent with estimates using reddening- and distance-free methods via the phases of the secondary maximum of the near-IR- (NIR-) band light curves. We also present 14 NIR spectra from -18 to +49 days relative to the B-band maximum light, providing constraints on the amount of swept-up hydrogen from the companion star in the context of the single degenerate progenitor scenario. No Pa beta emission feature was detected from our postmaximum NIR spectra, placing a hydrogen mass upper limit of 0.1 M. The overall optical/NIR photometric and NIR spectral evolution of SN 2017cbv is similar to that of a normal SN Ia, even though its early evolution is marked by a flux excess not seen in most other well-observed normal SNe Ia. We also compare the exquisite light curves of SN 2017cbv with some M-ch delayed detonation models and sub-M-ch double detonation models.

Here we review the achievements of volcano geodesy in Iceland during the last 15 years. Extensive measurements of crustal deformation have been conducted using a variety of geodetic techniques, including leveling, electronic distance measurements, campaign and continuous Global Positioning System (GPS) geodesy, and interferometric analysis of synthetic aperture radar images (InSAR). Results from these measurements provide a comprehensive view of the behavior of Icelandic volcanoes. Between inflation, intrusion, and eruption episodes, volcanoes are likely to deflate or show no sign of seismic activity. Subsidence rates are often in the range of a few millimeters to a few centimeters a year, reducing progressively with time since the last eruption or intrusion at the volcano. Subsidence can be caused by cooling and contraction of magma, outflow of magma, it can be related to plate spreading. Volcano subsidence or lack of deformation is often interrupted by episodic magma flow towards near-surface locations. Such magma recharge has been observed geodetically at Hengill, Hekla, Eyjafiallajokull, Katla, Grimsvotn, and Krafla volcanoes, with inflow inferred to last from a few months up to two decades. In the last 15 years, five volcanic eruptions, three intrusive events and two > M6 earthquakes have occurred. In recent years, the Grimsvotn and Katla volcanoes have exhibited continuous inflation of a few centimeters per year, which at Grimsvotn culminated in an eruption on I November 2004. Hekla and Torfajokull volcanoes have inflated at rates an order-of-magnitude less. Subsidence is occurring presently at the Askja and Krafla volcanoes. Within the period of geodetic measurement, signals consistent with no deformation are typical for most of the 35 active volcanoes in Iceland. (c) 2005 Elsevier B.V. All rights reserved.

Supernova (SN) 2017cbv in NGC 5643 is one of a handful of Type Ia supernovae (SNe Ia) reported to have excess blue emission at early times. This paper presents extensive BVRIYJHK(s)-band light curves of SN 2017cbv, covering the phase from -16 to +125 days relative to B-band maximum light. The SN 2017cbv reached a B-band maximum of 11.710 0.006 mag, with a postmaximum magnitude decline of Delta m(15)(B) = 0.990 0.013 mag. The SN suffered no host reddening based on Phillips intrinsic color, the Lira-Phillips relation, and the CMAGIC diagram. By employing the CMAGIC distance modulus mu = 30.58 0.05 mag and assuming H-0 = 72 km s(-1) Mpc(-1), we found that 0.73 M Ni-56 was synthesized during the explosion of SN 2017cbv, which is consistent with estimates using reddening- and distance-free methods via the phases of the secondary maximum of the near-IR- (NIR-) band light curves. We also present 14 NIR spectra from -18 to +49 days relative to the B-band maximum light, providing constraints on the amount of swept-up hydrogen from the companion star in the context of the single degenerate progenitor scenario. No Pa beta emission feature was detected from our postmaximum NIR spectra, placing a hydrogen mass upper limit of 0.1 M. The overall optical/NIR photometric and NIR spectral evolution of SN 2017cbv is similar to that of a normal SN Ia, even though its early evolution is marked by a flux excess not seen in most other well-observed normal SNe Ia. We also compare the exquisite light curves of SN 2017cbv with some M-ch delayed detonation models and sub-M-ch double detonation models.

Hekla is one of Iceland's most active volcanoes; its eruptions, characterized by surface fissuring and repeated lava flows during its post-glacial activity, have built up an 800 m high elongated mountain. Since 1970 it has erupted every similar to 10 years; the previous repose interval averaged similar to 60 years. For the last eruption in 2000 we constrain the magma geometry by using a wide variety of deformation data: campaign GPS; an InSAR interferogram; dry tilt data, and borehole strain data. The dike that causes surface fissuring extends no more than similar to 0.5 km in depth, and the reservoir depth is similar to 10 km. These are connected by a conduit of small lateral extent. Data for previous eruptions are consistent with this model. We propose that the marked change in eruption interval is because this conduit remains liquid during the short interval between recent eruptions; only a small pressure increase is required to rupture the thin crustal seat Such a state is consistent with precursory seismicity being confined to very shallow depths and may be applicable to other volcanoes that undergo abrupt changes in eruption interval. (C) 2013 Published by Elsevier B.V.

Some organelles cannot be synthesized anew, so they are segregated into daughter cells during cell division. In Saccharomyces cerevisiae, daughter cells bud from mother cells and are populated by organelles inherited from the mothers. To determine whether this organelle inheritance occurs in a stereotyped manner, we tracked organelles using fluorescence microscopy. We describe a program for organelle inheritance in budding yeast. The cortical endoplasmic reticulum (ER) and peroxisomes are inherited concomitantly with bud emergence. Next, vacuoles are inherited in small buds, followed closely by mitochondria. Finally, the nucleus and perinuclear ER are inherited when buds have nearly reached their maximal size. Because organelle inheritance timing correlates with bud morphology, which is coupled to the cell cycle, we tested whether disrupting the cell cycle alters organelle inheritance order. By arresting cell cycle progression but allowing continued bud growth, we determined that organelle inheritance still occurs when DNA replication is blocked, and that the general inheritance order is maintained. Thus, organelle inheritance follows a preferred order during polarized cell division and does not require completion of S-phase.

Yeast Rcl1 is a potential endonuclease that mediates pre-RNA cleavage at the A(2)-site to separate 18S rRNA from 5.8S and 25S rRNAs. However, the biological function of Rcl1 in opisthokonta is poorly defined. Moreover, there is no information regarding the exact positions of 18S pre-rRNA processing in zebrafish. Here, we report that zebrafish pre-rRNA harbours three major cleavage sites in the 5 ' ETS, namely -477nt (A '-site), -97nt (A(0)-site) and the 5 ' ETS and 18S rRNA link (A(1)-site), as well as two major cleavage regions within the ITS1, namely 208-218nt (site 2) and 20-33nt (site E). We also demonstrate that depletion of zebrafish Rcl1 mainly impairs cleavage at the A(1)-site. Phenotypically, rcl1(-/-) mutants exhibit a small liver and exocrine pancreas and die before 15 days post-fertilization. RNA-seq analysis revealed that the most significant event in rcl1(-/-) mutants is the up-regulated expression of a cohort of genes related to ribosome biogenesis and tRNA production. Our data demonstrate that Rcl1 is essential for 18S rRNA maturation at the A(1)-site and for digestive organogenesis in zebrafish. Rcl1 deficiency, similar to deficiencies in other ribosome biogenesis factors, might trigger a common mechanism to upregulate the expression of genes responsible for ribosome biogenesis.

We report a combined conventional Mossbauer and synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS) study of a series of basalt, andesite, dacite, and rhyolite glasses at temperatures ranging from 5 to 1223 K. These glasses were synthesized under controlled oxygen fugacities and span a wide range of Fe3+/Fe-tot ratios. As expected from theory, we find that in these glasses, the inverse of the Lamb-Mossbauer factor (the recoil-free fraction) correlates linearly with the fraction of the conventional Mossbauer spectrum that can be ascribed to Fe3+. Extrapolating the linear relationships to pure Fe3+ and Fe2+ endmembers yields a ratio for the Lamb-Mossbauer factors C of Fe3+ and Fe2+ of 1.203 & nbsp;+/- 0.017 (1r), with no clear dependence on the chemical composition of the glass. We show that the materials studied follow the harmonic approximation up to 1223 K for olivine and 773 K for basaltic glass, allowing us to extrapolate C in temperature. The temperature-dependence of C is well approximated by the formula C =& nbsp;(1.203 +/-& nbsp;0.033)(T=300) over the temperature range 50-750 K. This calibration is used to correct previous redox ratio determinations. We investigate how chemical composition and iron redox state influence the mean force constant of iron in glasses, a key driver of Fe isotopic fractionation during magma generation and differentiation. As previously documented by Dauphas et al. (2014), we find clear correlation between bond strength and iron redox ratio that is secondarily modulated by coordination effects in more alkali-rich felsic magmas. New data on sim-plified glass compositions reveal that network modifiers, notably K and Na, seem to exert an important control on Fe2+ bond strengths. The refined ratio of Mossbauer factors for Fe(2+ )and Fe3+ is used to improve on calibrations of iron redox state in geological glasses using XANES spectroscopy. We reevaluate the Fe3+/Fe-tot ratio of MORBs based on previously published XANES and Mossbauer data. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.

To further understand the long-debated origin of the high-pressure cubic-rhombohedral transition in FeO, we investigated the domain wall structure in Fe0.94O using high-pressure microdiffraction imaging techniques. The results reveal a non-reflection type domain wall structure forming due to the cubic-rhombohedral transition in Fe0.94O, which suggests the transformation could be associated with defects and is unlikely to be ferroelastic in nature. (C) 2012 American Institute of Physics. [doi:10.1063/1.3679117]