3,055 research outputs found
HAS DEPARTMENT OF DEFENSE ACQUISITION REFORM POLICY ADDRESSED THE PROBLEMS FACING ACQUISITIONS PROFESSIONALS?
This qualitative study analyzes how well recent acquisitions reform policies have addressed the modern difficulties facing acquisition professionals in an attempt to improve acquisition policy. The study reviews literature, case studies, surveys and interviews from previous program managers, and policy and legislation, and then compiles the aggregate results to develop a clearer view of how acquisition reform policy is addressing the problems faced by acquisition professionals. The primary goals of the study are to a) identify the main problems facing DOD acquisition, b) examine recent acquisition reform policies to determine if they address those issues identified, and c) provide recommendations for policy makers to shape acquisitions reforms and legislation in the future. Analysis of our findings suggests that defense acquisition policies and legislation are not addressing the critical issues faced by acquisition professionals and add layers of bureaucracy, further complicating the acquisitions process. Additional research into the factors effecting successful and unsuccessful acquisitions is warranted for a more thorough analysis.Lieutenant Commander, United States NavyLieutenant Commander, United States NavyLieutenant Commander, United States NavyApproved for public release. Distribution is unlimited
Relative effects of different non-vitamin K antagonist oral anticoagulants on global thrombotic status in atrial fibrillation
This is an Accepted Manuscript of an article published by Taylor & Francis GroupNon-vitamin K antagonist oral anticoagulants (NOACs) reduce the risk of thromboembolism in patients with atrial fibrillation (AF). There has been no head-to-head comparison of the effect of these agents on ex vivo thrombotic and thrombolytic status. Enhanced platelet reactivity and impaired endogenous thrombolysis are risk factors for recurrent thrombotic events. We aimed to assess the comparative effect of NOACs and warfarin using an ex vivo test of thrombosis and thrombolysis. Eighty patients with newly diagnosed non-valvular AF were tested before, and after being established on apixaban (n = 20), dabigatran (n = 20), rivaroxaban (n = 20), or warfarin (n = 20). Thrombotic status was assessed with the automated, point-of-care Global Thrombosis Test (GTT) that assesses both platelet reactivity and endogenous thrombolysis from native blood. The time taken to form an occlusive thrombus (occlusion time, OT) and the time required to restore flow through endogenous thrombolysis (lysis time, LT) were measured. All anticoagulants caused OT prolongation compared to baseline (apixaban 403 Β± 102s vs. 496 Β± 125s, p = 0.006; dabigatran 471 Β± 106s vs. 656 Β± 165s, p < 0.00001; rivaroxaban 381 Β± 119s vs. 579 Β± 158, p < 0.00001; warfarin 420 Β± 145s vs. 604 Β± 124s, p < 0.00001). Apixaban reduced LT from baseline (1895[1702-2167]s vs. 1435[347-1990]s; p = 0.006). A trend for LT reduction was seen with other NOACs (dabigatran 1594[1226-2069]s vs. 1539[561-2316]s, p = 0.499; rivaroxaban 2085[1366-2428]s vs. 1885[724-2420]s, p = 0.295) but not with warfarin (1490[1206-1960]s vs. 1776[1545-2334], p = 0.601). Our results suggest that NOACs and warfarin have a similar favorable effect on reducing platelet reactivity. All NOACs exhibited a trend toward enhancing endogenous thrombolytic status, although this was significant only for apixaban. This raises the possibility of using NOACs to enhance impaired endogenous fibrinolysis in patients at high-thrombotic risk.Peer reviewedFinal Accepted Versio
Examining student work for evidence of teacher uptake of educative curriculum materials
The purpose of this study was to identify evidence in student work of teachers' uptake of educative features in educative curriculum materials. These are features in curriculum materials designed with the specific intent of supporting teacher learning and enactment. This study was prompted by previous work on educative curriculum materials and the need to determine how teachers' use of educative curriculum materials can influence student learning. Student work from two fourthβgrade teachers' enactment of an electric circuits unit was analyzed for evidence of teachers' uptake of educative features, which included characteristics of quality for particular science practices. Findings from the student work revealed that the teachers used many of the supports in the educative curriculum materials, especially those that could be used directly with students. The student work also reflected characteristics of highβquality science practices, which were only supported within the educative features. This study supports and extends other work related to how teachers' use of educative curriculum materials may influence student learning and has implications for supporting teachers' productive engagement in teaching that supports the integration of science content and scientific practices, as emphasized in current reform efforts. Β© 2015 Wiley Periodicals, Inc. J Res Sci Teach 52: 816β846, 2015.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112188/1/tea21220-sup-0001-SuppFig_S3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112188/2/tea21220-sup-0001-SuppFig_S2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112188/3/tea21220.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112188/4/tea21220-sup-0001-SuppFig_S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112188/5/tea21220-sup-0001-SuppFig_S4.pd
SWI/SNF-like chromatin remodeling factor Fun30 supports point centromere function in S. cerevisiae
Budding yeast centromeres are sequence-defined point centromeres and are, unlike in many other organisms, not
embedded in heterochromatin. Here we show that Fun30, a poorly understood SWI/SNF-like chromatin remodeling factor
conserved in humans, promotes point centromere function through the formation of correct chromatin architecture at
centromeres. Our determination of the genome-wide binding and nucleosome positioning properties of Fun30 shows that
this enzyme is consistently enriched over centromeres and that a majority of CENs show Fun30-dependent changes in
flanking nucleosome position and/or CEN core micrococcal nuclease accessibility. Fun30 deletion leads to defects in histone
variant Htz1 occupancy genome-wide, including at and around most centromeres. FUN30 genetically interacts with CSE4,
coding for the centromere-specific variant of histone H3, and counteracts the detrimental effect of transcription through centromeres on chromosome segregation and suppresses transcriptional noise over centromere CEN3. Previous work has shown a requirement for fission yeast and mammalian homologs of Fun30 in heterochromatin assembly. As centromeres in budding yeast are not embedded in heterochromatin, our findings indicate a direct role of Fun30 in centromere chromatin by promoting correct chromatin architecture
Increased responsiveness of murine eosinophils to MIPΓ’ 1ΓΒ² (CCL4) and TCAΓ’ 3 (CCL1) is mediated by their specific receptors, CCR5 and CCR8
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141970/1/jlb1019.pd
Nucleotide, Cytogenetic and Expression Impact of the Human Chromosome 8p23.1 Inversion Polymorphism
Background: the human chromosome 8p23.1 region contains a 3.8-4.5 Mb segment which can be found in different orientations (defined as genomic inversion) among individuals. The identification of single nucleotide polymorphisms (SNPs) tightly linked to the genomic orientation of a given region should be useful to indirectly evaluate the genotypes of large genomic orientations in the individuals. Results: we have identified 16 SNPs, which are in linkage disequilibrium (LD) with the 8p23.1 inversion as detected by fluorescent in situ hybridization (FISH). The variability of the 8p23.1 orientation in 150 HapMap samples was predicted using this set of SNPs and was verified by FISH in a subset of samples. Four genes (NEIL2, MSRA, CTSB and BLK) were found differentially expressed (p<0.0005) according to the orientation of the 8p23.1 region. Finally, we have found variable levels of mosaicism for the orientation of the 8p23.1 as determined by FISH. Conclusion: by means of dense SNP genotyping of the region, haplotype-based computational analyses and FISH experiments we could infer and verify the orientation status of alleles in the 8p23.1 region by detecting two short haplotype stretches at both ends of the inverted region, which are likely the relic of the chromosome in which the original inversion occurred. Moreover, an impact of 8p23.1 inversion on gene expression levels cannot be ruled out, since four genes from this region have statistically significant different expression levels depending on the inversion status. FISH results in lymphoblastoid cell lines suggest the presence of mosaicism regarding the 8p23.1 inversion
H3 K36 Methylation Helps Determine the Timing of Cdc45 Association with Replication Origins
Replication origins fire at different times during S-phase. Such timing is determined by the chromosomal context, which includes the activity of nearby genes, telomeric position effects and chromatin structure, such as the acetylation state of the surrounding chromatin. Activation of replication origins involves the conversion of a pre-replicative complex to a replicative complex. A pivotal step during this conversion is the binding of the replication factor Cdc45, which associates with replication origins at approximately their time of activation in a manner partially controlled by histone acetylation.Here we identify histone H3 K36 methylation (H3 K36me) by Set2 as a novel regulator of the time of Cdc45 association with replication origins. Deletion of SET2 abolishes all forms of H3 K36 methylation. This causes a delay in Cdc45 binding to origins and renders the dynamics of this interaction insensitive to the state of histone acetylation of the surrounding chromosomal region. Furthermore, a decrease in H3 K36me3 and a concomitant increase in H3 K36me1 around the time of Cdc45 binding to replication origins suggests opposing functions for these two methylation states. Indeed, we find K36me3 depleted from early firing origins when compared to late origins genomewide, supporting a delaying effect of this histone modification for the association of replication factors with origins.We propose a model in which K36me1 together with histone acetylation advance, while K36me3 and histone deacetylation delay, the time of Cdc45 association with replication origins. The involvement of the transcriptionally induced H3 K36 methylation mark in regulating the timing of Cdc45 binding to replication origins provides a novel means of how gene expression may affect origin dynamics during S-phase
Viral elements and their potential influence on microbial processes along the permanently stratified Cariaco Basin redoxcline
Β© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mara, P., Vik, D., Pachiadaki, M. G., Suter, E. A., Poulos, B., Taylor, G. T., Sullivan, M. B., & Edgcomb, V. P. Viral elements and their potential influence on microbial processes along the permanently stratified Cariaco Basin redoxcline. ISME Journal, (2020), doi:10.1038/s41396-020-00739-3.Little is known about viruses in oxygen-deficient water columns (ODWCs). In surface ocean waters, viruses are known to act as gene vectors among susceptible hosts. Some of these genes may have metabolic functions and are thus termed auxiliary metabolic genes (AMGs). AMGs introduced to new hosts by viruses can enhance viral replication and/or potentially affect biogeochemical cycles by modulating key microbial pathways. Here we identify 748 viral populations that cluster into 94 genera along a vertical geochemical gradient in the Cariaco Basin, a permanently stratified and euxinic ocean basin. The viral communities in this ODWC appear to be relatively novel as 80 of these viral genera contained no reference viral sequences, likely due to the isolation and unique features of this system. We identify viral elements that encode AMGs implicated in distinctive processes, such as sulfur cycling, acetate fermentation, signal transduction, [FeβS] formation, and N-glycosylation. These AMG-encoding viruses include two putative Mu-like viruses, and viral-like regions that may constitute degraded prophages that have been modified by transposable elements. Our results provide an insight into the ecological and biogeochemical impact of viruses oxygen-depleted and euxinic habitats.This work was supported by the National Science Foundation grant OCE-1336082 to VPE, OCE-1335436 to GTT, OCE-1536989, a Moore Foundation Award (#3790) to MBS, and WHOI subaward A101259 to MP. The sequencing conducted by the U.S. Department of Energy Joint Genome Institute is supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC02-05CH11231
Secondary somatic mutations restoring RAD51C and RAD51D associated with acquired resistance to the PARP inhibitor rucaparib in high-grade ovarian carcinoma
High-grade epithelial ovarian carcinomas (OC) containing mutated BRCA1 or BRCA2 (BRCA1/2) homologous recombination (HR) genes are sensitive to platinum-based chemotherapy and poly(ADP-ribose) polymerase inhibitors (PARPi), while restoration of HR function due to secondary mutations in BRCA1/2 has been recognized as an important resistance mechanism. We sequenced core HR pathway genes in 12 pairs of pre-treatment and post-progression tumor biopsy samples collected from patients in ARIEL2 Part 1, a phase 2 study of the PARPi rucaparib as treatment for platinum-sensitive, relapsed OC. In six of 12 pre-treatment biopsies, a truncation mutation in BRCA1, RAD51C or RAD51D was identified. In five of six paired post-progression biopsies, one or more secondary mutations restored the open reading frame. Four distinct secondary mutations and spatial heterogeneity were observed for RAD51C. In vitro complementation assays and a patient-derived xenograft (PDX), as well as predictive molecular modeling, confirmed that resistance to rucaparib was associated with secondary mutations
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