5,650 research outputs found
Differential expression of conserved germ line markers and delayed segregation of male and female primordial germ cells in a hermaphrodite, the leech helobdella.
In sexually reproducing animals, primordial germ cells (PGCs) are often set aside early in embryogenesis, a strategy that minimizes the risk of genomic damage associated with replication and mitosis during the cell cycle. Here, we have used germ line markers (piwi, vasa, and nanos) and microinjected cell lineage tracers to show that PGC specification in the leech genus Helobdella follows a different scenario: in this hermaphrodite, the male and female PGCs segregate from somatic lineages only after more than 20 rounds of zygotic mitosis; the male and female PGCs share the same (mesodermal) cell lineage for 19 rounds of zygotic mitosis. Moreover, while all three markers are expressed in both male and female reproductive tissues of the adult, they are expressed differentially between the male and female PGCs of the developing embryo: piwi and vasa are expressed preferentially in female PGCs at a time when nanos is expressed preferentially in male PGCs. A priori, the delayed segregation of male and female PGCs from somatic tissues and from one another increases the probability of mutations affecting both male and female PGCs of a given individual. We speculate that this suite of features, combined with a capacity for self-fertilization, may contribute to the dramatically rearranged genome of Helobdella robusta relative to other animals
Is the āLinkage Principleā Valid?: Evidence from the Field
revenue comparison, auction choice, linkage principle, used-car auctions
Classification of Equivariant Complex Vector Bundles over a Circle
In this paper we characterize the fiber representations of equivariant
complex vector bundles over a circle and classify these bundles. We also treat
the triviality of equivariant complex vector bundles over a circle by
investigating the extensions of representations. As a corollary of our results,
we calculate the reduced equivariant K-group of a circle for any compact Lie
group.Comment: 15 pages, AMS-LaTeX v1.
Classification of equivariant real vector bundles over a circle
This is a continuation of the authors' previous work [math.AT/9910001] on
classification of equivariant complex vector bundles over a circle. In this
paper we classify equivariant real vector bundles over a circle with a compact
Lie group action, by characterizing the fiber representations of them, and by
using the result of the complex case. We also treat the triviality of them. The
basic phenomenon is similar to the complex case but more complicated here.Comment: 16 pages, AMS-LaTeX v1.
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Structural health monitoring (SHM) is a technique to diagnose an accurate and reliable condition of civil infrastructure by
collecting and analyzing responses from distributed sensors. In recent years, aging civil structures have been increasing and they
require further developed SHM technology for development of sustainable society. Wireless smart sensor and network technology,
which is one of the recently emerging SHM techniques, enables more effective and economic SHM system in comparison to the
existing wired systems. Researchers continue on development of the capability and extension of wireless smart sensors, and
implement performance validation in various in-laboratory and outdoor full-scale experiments. This paper presents a summary of
recent (mostly after 2010) researches on smart sensors, focused on the newly developed hardware, software, and validation
examples of the developed smart sensors.ope
LONG-TERM CLINICAL OUTCOME OF PATIENTS WITH ACUTE MYOCARDIAL INFARCTION COMPLICATED BY CARDIOGENIC SHOCK OR CARDIAC ARREST WHO RECEIVED EXTRACORPOREAL MEMBRANE OXYGENATION ASSISTED PRIMARY PERCUTANEOUS CORONARY INTERVENTION
Low off-state Leakage Currents in AlGaN/GaN High Electron Mobility Transistors By Employing A Highly Stressed SiNx Surface Passivation Layer
In this study, the impact of the stress in SiNx surface passivation layers on off-state drain and gate leakage currents and off-state breakdown voltage in AlGaN/GaN High Electron Mobility Transistors (HEMTs) is assessed. The SiNx films were deposited at room temperature by inductively coupled plasma chemical vapour deposition (ICP-CVD). Compared to unpassivated devices, the off-state drain and gate leakage currents of AlGaN/GaN HEMTs is increased by up to 2 orders of magnitude for a 200 nm thick SiNx passivation layer with 309 MPa compressive stress. The use of a bilayer SiNx passivation scheme comprising 70 nm SiNx with 309 MPa compressive stress followed by 130 nm SiNx with 880 MPa compressive stress resulted in off-state drain and gate leakage currents reduced by up to 1 order of magnitude when compared to unpassivated devices
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