Effects of Short Range Correlations on Ca Isotopes

The effect of Short Range Correlations (SRC) on Ca isotopes is studied using a simple phenomenological model. Theoretical expressions for the charge (proton) form factors, densities and moments of Ca nuclei are derived. The role of SRC in reproducing the empirical data for the charge density differences is examined. Their influence on the depletion of the nuclear Fermi surface is studied and the fractional occupation probabilities of the shell model orbits of Ca nuclei are calculated. The variation of SRC as function of the mass number is also discussed.Comment: 11 pages (RevTex), 6 Postscript figures available upon request at [email protected] Physical Review C in prin

Systematic study of the effect of short range correlations on the form factors and densities of s-p and s-d shell nuclei

Analytical expressions of the one- and two-body terms in the cluster expansion of the charge form factors and densities of the s-p and s-d shell nuclei with N=Z are derived. They depend on the harmonic oscillator parameter b and the parameter $\beta$ which originates from the Jastrow correlation function. These expressions are used for the systematic study of the effect of short range correlations on the form factors and densities and of the mass dependence of the parameters b and $\beta$. These parameters have been determined by fit to the experimental charge form factors. The inclusion of the correlations reproduces the experimental charge form factors at the high momentum transfers ($q\geq 2 1/fm$). It is found that while the parameter $\beta$ is almost constant for the closed shell nuclei, $^4$He, $^{16}$O and $^{40}$Ca, its values are larger (less correlated systems) for the open shell nuclei, indicating a shell effect in the closed shell nuclei.Comment: Latex, 21 pages, 6 figures, 1 tabl

Application of information entropy to nuclei

Shannon's information entropies in position- and momentum- space and their sum $S$ are calculated for various $s$-$p$ and $s$-$d$ shell nuclei using a correlated one-body density matrix depending on the harmonic oscillator size $b_0$ and the short range correlation parameter $y$ which originates from a Jastrow correlation function. It is found that the information entropy sum for a nucleus depends only on the correlation parameter $y$ through the simple relation $S= s_{0A} + s_{1A} y^{-\lambda_{sA}}$, where $s_{0A}$, $s_{1A}$ and $\lambda_{sA}$ depend on the mass number $A$. A similar approximate expression is also valid for the root mean square radius of the nucleus as function of $y$ leading to an approximate expression which connects $S$ with the root mean square radius. Finally, we propose a method to determine the correlation parameter from the above property of $S$ as well as the linear dependence of $S$ on the logarithm of the number of nucleons.Comment: 10 pages, 10 EPS figures, RevTeX, Phys.Rev.C accepted for publicatio

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Differential recognition of vascular and parenchymal beta amyloid deposition

By phage display, llama-derived heavy chain antibody fragments were selected from non-immune and immune libraries and tested for their affinity and specificity for beta amyloid by phage-ELISA, immunohistochemistry and surface plasmon resonance. We identified eight distinct heavy chain antibody fragments specific for beta amyloid. While three of them recognized vascular and parenchymal beta amyloid deposits, the remaining five heavy chain antibody fragments recognized vascular beta amyloid specifically, failing to bind to parenchymal beta amyloid. These heavy chain antibody fragments, selected from different libraries, demonstrated differential affinity for different epitopes when used for immunohistochemistry. These observations indicate that the llama heavy chain antibody fragments are the first immunologic probes with the ability to differentiate between parenchymal and vascular beta amyloid aggregates. This indicates that vascular and parenchymal beta amyloid deposits are heterogeneous in epitope presence/availability. The properties of these heavy chain antibody fragments make them potential candidates for use in in vivo differential diagnosis of Alzheimer disease and cerebral amyloid angiopathy. Continued use and characterization of these reagents will be necessary to fully understand the performance of these immunoreagents. (C) 2009 Elsevier Inc. All rights reserved.NEUR

Decoupling genetics, lineages, and microenvironment in IDH-mutant gliomas by single-cell RNA-seq.

Tumor subclasses differ according to the genotypes and phenotypes of malignant cells as well as the composition of the tumor microenvironment (TME). We dissected these influences in isocitrate dehydrogenase (IDH)-mutant gliomas by combining 14,226 single-cell RNA sequencing (RNA-seq) profiles from 16 patient samples with bulk RNA-seq profiles from 165 patient samples. Differences in bulk profiles between IDH-mutant astrocytoma and oligodendroglioma can be primarily explained by distinct TME and signature genetic events, whereas both tumor types share similar developmental hierarchies and lineages of glial differentiation. As tumor grade increases, we find enhanced proliferation of malignant cells, larger pools of undifferentiated glioma cells, and an increase in macrophage over microglia expression programs in TME. Our work provides a unifying model for IDH-mutant gliomas and a general framework for dissecting the differences among human tumor subclasses

Target gene sequencing to characterize the penicillin G susceptibility of Neisseria meningitidis36789

Clinical isolates of Neisseria meningitidis with reduced susceptibility to penicillin G (intermediate isolates, Pen(I)) harbor alterations in the penA gene encoding the penicillin binding protein 2 (PBP2). A 402-bp DNA fragment in the 3&#039; half of penA was sequenced from a collection of 1,670 meningococcal clinical isolates from 22 countries that spanned 60 years. Phenotyping, genotyping, and the determination of MICs of penicillin G were also performed. A total of 139 different penA alleles were detected with 38 alleles that were highly related, clustered together in maximum-likelihood analysis and corresponded to the penicillin G-susceptible isolates. The remaining 101 penA alleles were highly diverse, corresponded to different genotypes or phenotypes, and accounted for 38% of isolates, but no clonal expansion was detected. Analysis of the altered alleles that were represented by at least five isolates showed high correlation with the Pen(I) phenotype. The deduced amino acid sequence of the corresponding PBP2 comprised five amino acid residues that were always altered. This correlation was not complete for rare alleles, suggesting that other mechanisms may also be involved in conferring reduced susceptibility to penicillin. Evidence of mosaic structures through events of interspecies recombination was also detected in altered alleles. A new website was created based on the data from this work (http://neisseria.org/nm/typing/penA). These data argue for the use of penA sequencing to identify isolates with reduced susceptibility to penicillin G and as a tool to improve typing of meningococcal isolates, as well as to analyze DNA exchange among Neisseria species</p

Developmental and oncogenic programs in H3K27M gliomas dissected by single-cell RNA-seq.

Gliomas with histone H3 lysine27-to-methionine mutations (H3K27M-glioma) arise primarily in the midline of the central nervous system of young children, suggesting a cooperation between genetics and cellular context in tumorigenesis. Although the genetics of H3K27M-glioma are well characterized, their cellular architecture remains uncharted. We performed single-cell RNA sequencing in 3321 cells from six primary H3K27M-glioma and matched models. We found that H3K27M-glioma primarily contain cells that resemble oligodendrocyte precursor cells (OPC-like), whereas more differentiated malignant cells are a minority. OPC-like cells exhibit greater proliferation and tumor-propagating potential than their more differentiated counterparts and are at least in part sustained by &lt;i&gt;PDGFRA&lt;/i&gt; signaling. Our study characterizes oncogenic and developmental programs in H3K27M-glioma at single-cell resolution and across genetic subclones, suggesting potential therapeutic targets in this disease