Magnetic state of plutonium ion in metallic Pu and its compounds

By LDA+U method with spin-orbit coupling (LDA+U+SO) the magnetic state and electronic structure have been investigated for plutonium in \delta and \alpha phases and for Pu compounds: PuN, PuCoGa5, PuRh2, PuSi2, PuTe, and PuSb. For metallic plutonium in both phases in agreement with experiment a nonmagnetic ground state was found with Pu ions in f^6 configuration with zero values of spin, orbital, and total moments. This result is determined by a strong spin-orbit coupling in 5f shell that gives in LDA calculation a pronounced splitting of 5f states on f^{5/2} and f^{7/2} subbands. A Fermi level is in a pseudogap between them, so that f^{5/2} subshell is already nearly completely filled with six electrons before Coulomb correlation effects were taken into account. The competition between spin-orbit coupling and exchange (Hund) interaction (favoring magnetic ground state) in 5f shell is so delicately balanced, that a small increase (less than 15%) of exchange interaction parameter value from J_H=0.48eV obtained in constrain LDA calculation would result in a magnetic ground state with nonzero spin and orbital moment values. For Pu compounds investigated in the present work, predominantly f^6 configuration with nonzero magnetic moments was found in PuCoGa5, PuSi2, and PuTe, while PuN, PuRh2, and PuSb have f^5 configuration with sizeable magnetic moment values. Whereas pure jj coupling scheme was found to be valid for metallic plutonium, intermediate coupling scheme is needed to describe 5f shell in Pu compounds. The results of our calculations show that both spin-orbit coupling and exchange interaction terms in the Hamiltonian must be treated in a general matrix form for Pu and its compounds.Comment: 20 pages, LaTeX; changed discussion on reference pape

Female bone physiology resilience in 750-300 BP ‘Polynesian Outlier’ community

Remodelling is a fundamental biological process involved in the maintenance of bone physiology and function. We know that a range of health and lifestyle factors can impact this process in living and past societies, but there is a notable gap in bone remodelling data for populations from the Pacific Islands. We conducted the first examination of femoral cortical histology in n = 69 individuals from 750 – 300 BP Taumako in Solomon Islands, a remote ‘Polynesian Outlier’ island in Melanesia. We tested whether bone remodelling indicators differed between age-at-death groups, and biological sex validated using ancient DNA. Bone vascular canal and osteon size, vascular porosity, and localised osteon densities, corrected by femoral robusticity indices were examined. Females had statistically significantly higher vascular porosities when compared to males, but osteon densities and ratios of canal-to-osteon (~10%) did not differ between the sexes. Compared to males, the femora of Taumako females experienced higher frequencies of remodelling events, which mirrors bone health paradigms through the life-course today. However, contrary to modern populations, female femoral bone tissue did not decline with age. This matches findings in other archaeological samples, and is testament to ancient female bone physiology resilience also in the Pacific region.Introduction - The importance of bone remodelling through human life-course - Bone remodelling in archaeological humans Results - Trends in bone remodelling at Taumako Discussion - Sex-specific trends in cortical bone remodelling - Bone remodelling with age at Taumako Limitations and remarks on temporal and spatial data Conslusions Materials and Method

Female bone physiology resilience in a past Polynesian Outlier community

Remodelling is a fundamental biological process involved in the maintenance of bone physiology and function. We know that a range of health and lifestyle factors can impact this process in living and past societies, but there is a notable gap in bone remodelling data for populations from the Pacific Islands. We conducted the first examination of femoral cortical histology in 69 individuals from ca. 440–150 BP Taumako in Solomon Islands, a remote ‘Polynesian Outlier’ island in Melanesia. We tested whether bone remodelling indicators differed between age groups, and biological sex validated using ancient DNA. Bone vascular canal and osteon size, vascular porosity, and localised osteon densities, corrected by femoral robusticity indices were examined. Females had statistically significantly higher vascular porosities when compared to males, but osteon densities and ratios of canal-osteon (~ 8%) did not differ between the sexes. Our results indicate that, compared to males, localised femoral bone tissue of the Taumako females did not drastically decline with age, contrary to what is often observed in modern populations. However, our results match findings in other archaeological samples—a testament to past female bone physiology resilience, also now observed in the Pacific region.Introduction - Bone remodelling through human life‑course. - Bone remodelling in archaeological humans. Results - Femoral vascular porosity and bone remodelling indicators at Taumako. Discussion - Sex and cortical bone histology at Taumako. - The effect of age on bone histology at Taumako. Remarks on temporal and spatial bone histology data Limitations Conclusions Materials and method

Long-Term Seizure Suppression and Optogenetic Analyses of Synaptic Connectivity in Epileptic Mice with Hippocampal Grafts of GABAergic Interneurons

Studies in rodent epilepsy models suggest that GABAergic interneuron progenitor grafts can reduce hyperexcitability and seizures in temporal lobe epilepsy (TLE). Although integration of the transplanted cells has been proposed as the underlying mechanism for these disease-modifying effects, prior studies have not explicitly examined cell types and synaptic mechanisms for long-term seizure suppression. To address this gap, we transplanted medial ganglionic eminence (MGE) cells from embryonic day 13.5 VGAT-Venus or VGAT-ChR2-EYFP transgenic embryos into the dentate gyrus (DG) of adult mice 2 weeks after induction of TLE with pilocarpine. Beginning 3–4 weeks after status epilepticus, we conducted continuous video-electroencephalographic recording until 90–100 d. TLE mice with bilateral MGE cell grafts in the DG had significantly fewer and milder electrographic seizures, compared with TLE controls. Immunohistochemical studies showed that the transplants contained multiple neuropeptide or calcium-binding protein-expressing interneuron types and these cells established dense terminal arborizations onto the somas, apical dendrites, and axon initial segments of dentate granule cells (GCs). A majority of the synaptic terminals formed by the transplanted cells were apposed to large postsynaptic clusters of gephyrin, indicative of mature inhibitory synaptic complexes. Functionality of these new inhibitory synapses was demonstrated by optogenetically activating VGAT-ChR2-EYFP-expressing transplanted neurons, which generated robust hyperpolarizations in GCs. These findings suggest that fetal GABAergic interneuron grafts may suppress pharmacoresistant seizures by enhancing synaptic inhibition in DG neural circuits

A contiguous de novo genome assembly of sugar beet EL10 (Beta vulgaris L.)

A contiguous assembly of the inbred ‘EL10’ sugar beet (Beta vulgaris ssp. vulgaris) genome was constructed using PacBio long-read sequencing, BioNano optical mapping, Hi-C scaffolding, and Illumina short-read error correction. The EL10.1 assembly was 540 Mb, of which 96.2% was contained in nine chromosome-sized pseudomolecules with lengths from 52 to 65 Mb, and 31 contigs with a median size of 282 kb that remained unassembled. Gene annotation incorporating RNA-seq data and curated sequences via the MAKER annotation pipeline generated 24,255 gene models. Results indicated that the EL10.1 genome assembly is a contiguous genome assembly highly congruent with the published sugar beet reference genome. Gross duplicate gene analyses of EL10.1 revealed little large-scale intra-genome duplication. Reduced gene copy number for well-annotated gene families relative to other core eudicots was observed, especially for transcription factors. Variation in genome size in B. vulgaris was investigated by flow cytometry among 50 individuals producing estimates from 633 to 875 Mb/1C. Read-depth mapping with short-read whole-genome sequences from other sugar beet germplasm suggested that relatively few regions of the sugar beet genome appeared associated with high-copy number variation

Absence of system xc⁻ on immune cells invading the central nervous system alleviates experimental autoimmune encephalitis

Background: Multiple sclerosis (MS) is an autoimmune demyelinating disease that affects the central nervous system (CNS), leading to neurodegeneration and chronic disability. Accumulating evidence points to a key role for neuroinflammation, oxidative stress, and excitotoxicity in this degenerative process. System x(c)- or the cystine/glutamate antiporter could tie these pathological mechanisms together: its activity is enhanced by reactive oxygen species and inflammatory stimuli, and its enhancement might lead to the release of toxic amounts of glutamate, thereby triggering excitotoxicity and neurodegeneration. Methods: Semi-quantitative Western blotting served to study protein expression of xCT, the specific subunit of system x(c)-, as well as of regulators of xCT transcription, in the normal appearing white matter (NAWM) of MS patients and in the CNS and spleen of mice exposed to experimental autoimmune encephalomyelitis (EAE), an accepted mouse model of MS. We next compared the clinical course of the EAE disease, the extent of demyelination, the infiltration of immune cells and microglial activation in xCT-knockout (xCT(-/-)) mice and irradiated mice reconstituted in xCT(-/-) bone marrow (BM), to their proper wild type (xCT(+/+)) controls. Results: xCT protein expression levels were upregulated in the NAWM of MS patients and in the brain, spinal cord, and spleen of EAE mice. The pathways involved in this upregulation in NAWM of MS patients remain unresolved. Compared to xCT(+/+) mice, xCT(-/-) mice were equally susceptible to EAE, whereas mice transplanted with xCT(-/-) BM, and as such only exhibiting loss of xCT in their immune cells, were less susceptible to EAE. In none of the above-described conditions, demyelination, microglial activation, or infiltration of immune cells were affected. Conclusions: Our findings demonstrate enhancement of xCT protein expression in MS pathology and suggest that system x(c)- on immune cells invading the CNS participates to EAE. Since a total loss of system x(c)- had no net beneficial effects, these results have important implications for targeting system x(c)- for treatment of MS

Nature of the 5f states in actinide metals

Actinide elements produce a plethora of interesting physical behaviors due to the 5f states. This review compiles and analyzes progress in understanding of the electronic and magnetic structure of the 5f states in actinide metals. Particular interest is given to electron energy-loss spectroscopy and many-electron atomic spectral calculations, since there is now an appreciable library of core d -> valence f transitions for Th, U, Np, Pu, Am, and Cm. These results are interwoven and discussed against published experimental data, such as x-ray photoemission and absorption spectroscopy, transport measurements, and electron, x-ray, and neutron diffraction, as well as theoretical results, such as density-functional theory and dynamical mean-field theory.Comment: 136 pages in Word format, 29 Figures; Accepted to Reviews of Modern Physic

Electronic structure and magnetic properties of selected lanthanide and actinide intermetallic Laves-phase alloys

The electronic structure and magnetic properties of some yttrium and uranium Laves-phase pseudobinary alloys with 3d elements have been calculated. The calculations were done by simulating the electronic structure of the alloy by that of an ordered compound with the same stoichiometry. In general a good agreement between the experimental and theoretical magnetic moment was found, indicating that the spurious long-range order of the calculations is of minor importance. A comparison between the present supercell cluster approach and the virtual-crystal approximation for the electronic structure and cohesive properties is presented for Y(Fe0.75Co0.25)2 and U(Fe0.5Ni0.5)2