27 research outputs found
SURVEY OF THE DEPENDENCE ON TEMPERATURE OF THE COERCIVITY OF GARNET-FILMS
The temperature dependence of the domain-wall coercive field of epitaxial magnetic garnets films
has been investigated in the entire temperature range of the ferrimagnetic phase, and has been found
to be described by a set of parametric exponents. In subsequent temperature regions different slopes
were observed, with breaking points whose position was found to be sample dependent. A survey
ba.ed on literature Data as well as on a large number of our own samples shows the general
existence of this piecewise exponential dependence and the presence of the breaking points. This
type of domain-wall coercive field temperature dependence was found in all samples in the large
family of the epitaxial garnets (about 30 specimens of more than ten chemical compositionsj and
also in another strongly anisotropic material (TbFeCo)
A holin and an endopeptidase are essential for chitinolytic protein secretion in <i>Serratia marcescens</i>
Pathogenic bacteria adapt to their environment and manipulate the biochemistry of hosts by secretion of effector molecules. Serratia marcescens is an opportunistic pathogen associated with healthcare-acquired infections and is a prolific secretor of proteins, including three chitinases (ChiA, ChiB, and ChiC) and a chitin binding protein (Cbp21). In this work, genetic, biochemical, and proteomic approaches identified genes that were required for secretion of all three chitinases and Cbp21. A genetic screen identified a holin-like protein (ChiW) and a putative l-alanyl-d-glutamate endopeptidase (ChiX), and subsequent biochemical analyses established that both were required for nonlytic secretion of the entire chitinolytic machinery, with chitinase secretion being blocked at a late stage in the mutants. In addition, live-cell imaging experiments demonstrated bimodal and coordinated expression of chiX and chiA and revealed that cells expressing chiA remained viable. It is proposed that ChiW and ChiX operate in tandem as components of a protein secretion system used by gram-negative bacteria
Palaeoclimatic events, dispersal and migratory losses along the Afro-European axis as drivers of biogeographic distribution in Sylvia warblers
<p>Abstract</p> <p>Background</p> <p>The Old World warbler genus <it>Sylvia </it>has been used extensively as a model system in a variety of ecological, genetic, and morphological studies. The genus is comprised of about 25 species, and 70% of these species have distributions at or near the Mediterranean Sea. This distribution pattern suggests a possible role for the Messinian Salinity Crisis (from 5.96-5.33 Ma) as a driving force in lineage diversification. Other species distributions suggest that Late Miocene to Pliocene Afro-tropical forest dynamics have also been important in the evolution of <it>Sylvia </it>lineages. Using a molecular phylogenetic hypothesis and other methods, we seek to develop a biogeographic hypothesis for <it>Sylvia </it>and to explicitly assess the roles of these climate-driven events.</p> <p>Results</p> <p>We present the first strongly supported molecular phylogeny for <it>Sylvia</it>. With one exception, species fall into one of three strongly supported clades: one small clade of species distributed mainly in Africa and Europe, one large clade of species distributed mainly in Africa and Asia, and another large clade with primarily a circum-Mediterranean distribution. Asia is reconstructed as the ancestral area for <it>Sylvia</it>. Long-distance migration is reconstructed as the ancestral character state for the genus, and sedentary behavior subsequently evolved seven times.</p> <p>Conclusion</p> <p>Molecular clock calibration suggests that <it>Sylvia </it>arose in the early Miocene and diverged into three main clades by 12.6 Ma. Divergence estimates indicate that the Messinian Salinity Crisis had a minor impact on <it>Sylvia</it>. Instead, over-water dispersals, repeated loss of long-distance migration, and palaeo-climatic events in Africa played primary roles in <it>Sylvia </it>divergence and distribution.</p
Genome-wide Analyses Identify KIF5A as a Novel ALS Gene
To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.Peer reviewe
The Activities and Impact of State Programs to Address Hereditary Breast and Ovarian Cancer, 2011–2014
In 2011, the Division of Cancer Prevention and Control (DCPC), at the United States Centers for Disease Control and Prevention (CDC), released a three-year funding opportunity announcement (FOA) for a competitive, non-research cooperative agreement. The agreement enhanced the capacities of state health departments to promote the application of best practices for evidence-based breast cancer genomics through education, surveillance, and policy activities. The FOA required that applicants focus on activities related to hereditary breast and ovarian cancer (HBOC). The DCPC funded three states: Georgia, Michigan, and Oregon. Georgia was a first-time recipient of cancer genomics funding, whereas Michigan and Oregon had long standing activities in cancer genomics and had received CDC funding in the past. By the end of the funding period, each state had well-functioning and impactful state-based programs in breast cancer genomics. This article highlights the impact of a few key state activities by using CDC’s Science Impact Framework. There were challenges to implementing public health genomics programs, including the need to develop relevant partnerships, the highly technical nature of the subject matter, a lack of genetic services in certain areas, and the difficulty in funding genetic services. Georgia, Michigan, and Oregon have served as models for others interested in initiating or expanding cancer genomics programs, and they helped to determine what works well for promoting and integrating public health genomics into existing systems
Product Differentiation and the Use of Information Technology: New Evidence from the Trucking Industry,&quot; mimeo
Institute’s third annual conference at Atlantic City for many helpful comments. Research assistance wa