Steiner triple systems of order 21 with subsystems

The smallest open case for classifying Steiner triple systems is order 21. A Steiner triple system of order 21, an STS((21)), can have subsystems of orders 7 and 9, and it is known that there are 12,661,527,336 isomorphism classes of STS((21))s with sub-STS((9))s. Here, the classification of STS((21))s with subsystems is completed by settling the case of STS((21))s with sub-STS((7))s. There are 116,635,963,205,551 isomorphism classes of such systems. An estimation of the number of isomorphism classes of STS((21))s is given

63^{63}Cu(I) binding to human kidney 68^{68}Zn7_7-βα MT1A: determination of Cu(I)-thiolate cluster domain specificity from ESI-MS and room temperature phosphorescence spectroscopy

Mammalian metallothioneins (MTs) are important proteins in Zn(II) and Cu(I) homeostasis with the Zn(II) and Cu(I) binding to the 20 cysteines in metal-thiolate clusters. Previous electrospray ionization (ESI) mass spectrometric (MS) analyses of Cu(I) binding to Zn$_7$-MT were complicated by significant overlap of the natural abundance isotopic patterns for Zn(II) and Cu(I) leading to impossibly ambiguous stoichiometries. In this paper, isotopically pure $^{63}$Cu(I) and $^{68}$Zn(II) allowed determination of the specific stoichiometries in the $^{68}$Zn,$^{63}$Cu-βα MT1A species formed following the stepwise addition of $^{63}$Cu(I) to $^{68}$Zn$_7$-βα MT1A. These species were characterized by ESI-MS and room temperature emission spectroscopy. The key species that form and their emission band centres are Zn$_5$Cu$_5$-βα MT1A (λ = 684 nm), Zn$_4$Cu$_6$-βα MT1A (λ = 750 nm), Zn$_3$Cu$_9$-βα MT1A (λ = 750 nm), Zn$_2$Cu$_{10}$-βα MT1A (λ = 750 nm), and Zn$_1$Cu$_{14}$-βα MT1A (λ = 634 nm). The specific domain stoichiometry of each species was determined by assessing the species forming following $^{63}$Cu(I) addition to the $^{68}$Zn$_3$-β MT1A and $^{68}$Zn$_4$-α MT1A domain fragments. The domain fragment emission suggests that Zn$_5$Cu$_5$-βα MT1A contains a Zn$_1$Cu$_5$-β cluster and the Zn$_4$Cu$_6$-βα MT1A, Zn$_3$Cu$_9$-βα MT1A, and Zn$_2$Cu$_{10}$-βα MT1A each contain a Cu$_6$-β cluster. The species forming with >10 mol. eq. of $^{63}$Cu(I) in βα-MT1A exhibit emission from the Cu$_6$-β cluster and an α domain cluster. This high emission intensity is seen at the end of the titrations of $^{68}$Zn$_7$-βα MT1A and the $^{68}$Zn$_4$-α MT1A domain fragment suggesting that the initial presence of the Zn(II) results in clustered Cu(I) binding in the α domain

Improved thickness measurement on rough surfaces by using guided wave cut-off frequency

Substantial variability is seen when thickness measurements using conventional ultrasonic time of flight measurements are carried out on rough surfaces; this makes it difficult to estimate corrosion rates when the corrosion mechanism leads to surface roughness. It has been shown that thickness measurements using guided wave cut-off frequencies (through thickness resonance frequencies) can be done at much lower frequencies than conventional time of flight thickness gauging for the same minimum thickness resolution. The lower frequency measurements are less susceptible to variations caused by surface roughness and so will give more consistent and reliable results in cases where corrosion leads to increased surface roughness. Measurements were carried out using guided wave cut-off frequencies on four plates with different surface roughness. On a plate with root mean square (rms) surface roughness of 0.3 mm, the thickness estimates followed the trend predicted from the plate geometry and probe footprint, whereas higher frequency measurements reported in the literature deviated from this trend at an rms roughness of 0.1 mm. The guided wave cut-offcut-off frequency measurements can be done using the same transduction system as that used for large area guided wave monitoring so it is possible to combine large and small area monitoring in a single unit. Frequent measurements enable the wall thickness obtained with guided wave cut-off measurements to be tracked with time, and the low susceptibility of the measurements to surface roughness means that accurate corrosion rates will be obtained

Properties of Bicentric Circles for Three-Sided Polygons

We define and construct bicentric circles with respect to three-sided polygons. Then using inherent properties of these circles, we explore both tangent properties, and areas generated from bicentric circles

The HST Cosmos Project: Contribution from the Subaru Telescope

The Cosmic Evolution Survey (COSMOS) is a Hubble Space Telescope (HST) treasury project.The COSMOS aims to perform a 2 square degree imaging survey of an equatorial field in $I$(F814W) band, using the Advanced Camera for Surveys (ACS). Such a wide field survey, combined with ground-based photometric and spectroscopic data, is essential to understand the interplay between large scale structure, evolution and formation of galaxies and dark matter. In 2004, we have obtained high-quality, broad band images of the COSMOS field ($B, V, r^\prime, i^\prime,$ and $z^\prime$) using Suprime-Cam on the Subaru Telescope, and we have started our new optical multi-band program, COSMOS-21 in 2005. Here, we present a brief summary of the current status of the COSMOS project together with contributions from the Subaru Telescope. Our future Subaru program, COSMOS-21, is also discussed briefly.Comment: 4 pages, 3 figures, to appear in the Proceedings of the 6th East Asian Meeting on Astronomy, JKAS, 39, in pres

Arabidopsis KCBP interacts with AIR9 but stays in the cortical division zone throughout mitosis via its MyTH4-FERM domain

The preprophase band of microtubules performs the crucial function of marking the plane of cell division. Although the preprophase band depolymerises at the onset of mitosis, the division plane is 'memorized' by a cortical division zone to which the phragmoplast is attracted during cytokinesis. Proteins have been discovered that are part of the molecular memory but little is known about how they contribute to phragmoplast guidance. Previously, we found that the microtubule-associated protein AIR9 is found in the cortical division zone at preprophase and returns during cell plate insertion but is absent from the cortex during the intervening mitosis. To identify new components of the preprophase memory, we searched for proteins that interact with AIR9. We detected the kinesin-like calmodulin-binding protein, KCBP, which can be visualized at the predicted cortical site throughout division. A truncation study of KCBP indicates that its MyTH4-FERM domain is required for linking the motor domain to the cortex. These results suggest a mechanism by which minus-end-directed KCBP helps guide the centrifugally expanding phragmoplast to the cortical division site.Instituto de Biotecnologia y Biologia Molecula

Dual roles for LUBAC signaling in thymic epithelial cell development and survival

Thymic epithelial cells (TECs) form a unique microenvironment that orchestrates T cell differentiation and immunological tolerance. Despite the importance of TECs for adaptive immunity, there is an incomplete understanding of the signalling networks that support their differentiation and survival. We report that the linear ubiquitin chain assembly complex (LUBAC) is essential for medullary TEC (mTEC) differentiation, cortical TEC survival and prevention of premature thymic atrophy. TEC-specific loss of LUBAC proteins, HOIL-1 or HOIP, severely impaired expansion of the thymic medulla and AIRE-expressing cells. Furthermore, HOIL-1-deficiency caused early thymic atrophy due to Caspase-8/MLKL-dependent apoptosis/necroptosis of cortical TECs. By contrast, deficiency in the LUBAC component, SHARPIN, caused relatively mild defects only in mTECs. These distinct roles for LUBAC components in TECs correlate with their function in linear ubiquitination, NFκB activation and cell survival. Thus, our findings reveal dual roles for LUBAC signaling in TEC differentiation and survival

Trajectory and orbit of the unique carbonaceous meteorite Flensburg

Stars and planetary system