Pieces of nilpotent cones for classical groups

We compare orbits in the nilpotent cone of type $B_n$, that of type $C_n$, and Kato's exotic nilpotent cone. We prove that the number of \F_q-points in each nilpotent orbit of type $B_n$ or $C_n$ equals that in a corresponding union of orbits, called a type-$B$ or type-$C$ piece, in the exotic nilpotent cone. This is a finer version of Lusztig's result that corresponding special pieces in types $B_n$ and $C_n$ have the same number of \F_q-points. The proof requires studying the case of characteristic 2, where more direct connections between the three nilpotent cones can be established. We also prove that the type-$B$ and type-$C$ pieces of the exotic nilpotent cone are smooth in any characteristic.Comment: 32 page

The Chemical and Physical Properties of Tourmaline

The decomposition temperature of schorl was found to be 880 ± 10°C using X-ray and optical methods. The main crystalline product in decomposed schorl and dravite was found to be a boron containing mullrte, the composition of this phase was found to become closer to that of mullite (3Al203.2Si02) as the decomposition temperature was increased. The size of these possibly slightly.orientated needle shaped microcrystals was approximately 25 ± 10 u by 3 ± 2 u by 3 ± 2 u. The main decompostion products obtained in reducing conditions, in addition to the boron containing mudite, were hercynite {FeO-Al203} at low temperatures and oC— iron at higher temperatures. The decomposition temperature:; of schorl in the presence of activated charcoal was found to be at least 60^C lower than that for air decomposed schorl. This decrease was thought to be associated wcth the formation of hercynite by a low temperature reaction between schorl and activated charcoal. The boric oxide and Iron oxide in air decomposed schorl were both extracted by dilute acid. The rate of extraction was found to increase as the original schorl decomposition temperature was increased. The activation energy for the extraction of boric oxide as a function of the schorl decomposition temperature was found to be equal to 19.2 ± 0.4 kcal/mole. This increase in the rate of extraction of boric oxide was suggested to be associated with the separation and growth of micro-regions of a boron rich phase within the silica-iron oxide amorphous matrix. The activation energy for the extraction of boric oxide as a function of the leaching temperature was found to be equal to 7.99 ± 0.19 kcal/mole, whilst the activation energy for the extraction of iron oxide from air decomposed schorl was found to be equal to 7.13 ± 1.06 kcal/mole. The similarity between these values and that of 6.8 kcal/mole for the activation energy oftacTid leaching of phase-separated borosilicate glass (138), was thought to provide further indirect evidence for the suggestion that the amorphous phase in decomposed schorl contains phase separated micro-regions. The rate of extraction of both boric oxide and iron from schorl decomposed in reducing conditions was found to be considerably faster than from air decomposed schorl. This increased extractability was thought to be connected with the presence of micro-crystals of iron in the decomposed reduced schorl. The boric oxide present in both schorl and dravlte was found to be extractable if water vapour was passed over the decomposed minerals at temperatures above 1000*c. The activation energy for the extraction of boric oxide by pyrohydrolysis from decomposed schorl was found to be equal to 85 ± 8 kcal/mole, whilst the activation energy for the extraction of boric oxide by pyrohydrolysis from both decomposed dravite and "pyrex" glass was found to be equal to 22 ±1 kcal/mole. The higher value was thought to be due to the incorporation of Fe2+ ions into the amorphous silica lattice in decomposed schorl. This process was suggested to lead to an increase in the energy barrier towards the diffusion of water vapour through the silica-iron oxide amorphous matrix to the boron rich reaction surface

Monovalent cation induced structural transitions in telomeric DNAs: G-DNA folding intermediates

Telomeric DNA consists of G- and C-rich strands that are always polarized such that the G-rich strand extends past the 3’ end of the duplex to form a 12-16-base overhang. These overhanging strands can self-associate in vitro to form intramolecular structures that have several unusual physical properties and at least one common feature, the presence of non-Watson-Crick G-G base pairs. The term “G-DNA” was coined for this class of structures (Cech, 1988). On the basis of gel electrophoresis, imino proton NMR, and circular dichroism (CD) results, we find that changing the counterions from sodium to potassium (in 20 mM phosphate buffers) specifically induces conformational transitions in the G-rich telomeric DNA from Tetrahymena, d(T2G4)4 (TET4), which results in a change from the intramolecular species to an apparent multistranded structure, accompanied by an increase in the melting temperature of the base pairs of \u3e 2 5 O , as monitored by loss of the imino proton NMR signals. NMR semiselective spin-lattice relaxation rate measurements and HPLC size-exclusion chromatography studies show that in 20 mM potassium phosphate (pH 7) buffer (KP) TET4 is approximately twice the length of the form obtained in 20 mM sodium phosphate (pH 7) buffer (Nap) and that mixtures of Na+ and K+ produce mixtures of the two forms whose populations depend on the ratio of the cations. Since K+ and NH4+ are known to stabilize a parallel-stranded quadruplex structure of poly[r(I),], we infer that the multistranded structure is a quadruplex. Our results indicate that specific differences in ionic interactions can result in a switch in telomeric DNAs between intramolecular hairpin-like or quadruplex-containing species and intermolecular quadruplex structures, all of which involve G G base pairing interactions. We propose a model in which duplex or hairpin forms of G-DNA are folding intermediates in the formation of either 1-, 2-, or 4-stranded quadruplex structures. In this model monovalent cations stabilize the duplex and quadruplex forms via two distinct mechanisms, counterion condensation and octahedral coordination to the carbonyl groups in stacked planar guanine “quartet” base assemblies. Substituting one of the guanosine residues in each of the repeats of the Tetrahymena sequence to give the human telomeric DNA, d(T2AG,)4, results in less effective K+-dependent stabilization. Thus, the ion-dependent stabilization is attenuated by altering the sequence. Upon addition of the Watson-Crick (WC) complementary strand, only the Na+-stabilized structure dissociates quickly to form a WC double helix. This demonstrates that under some circumstances the K+-stabilized G-DNA structure can be kinetically preferred over WC DNA

Height referencing biochemical cassette

A height referencing biochemical cassette comprising of a surface suitable to act as a coupling agent, a height referencing indicator, and molecules bonded to the surface. This cassette is a capable of use to test for bonding to these molecules through measuring the height difference between the indicator and the surface. This invention provides an efficient means to quickly and easily test for bonding of molecules to other molecules

Structured Visions In The Novels Of John Hawkes

John Hawkes\u27 novels can be seen as expressing a dialectic between the act of fictional ordering and the chaos of a reality which is potentially subject to the ordering process but which ultimately threatens to dissolve such designs as are present in created or fictional reality. Both Hawkes and many of his protagonists, particularly his first-person narrators, are determined to create a world. As creators and visionary artists, they manifest a need to transform or transcend those forces which oppress them and oppose their efforts to create self-contained worlds based on principles of order, design and clarity; as embodiments of an ordering aesthetic, they battle against the powers of anti-art and often a specific antagonist who represents these powers.;The worlds of such visionary artists are unstable; they reflect creative man\u27s endeavors to impose meaningful order rather than the enduring strength of aesthetic imperatives. In Hawkes\u27 earliest fiction, the artist-figure is stifled by external forces; anti-art in its various forms dominates the worlds of The Cannibal and The Beetle Leg. It is Hawkes himself, through linguistic and stylistic devices, through the structuring capacity, who exhibits the authorial (and authoritarian) need to impose a sense of order and coherence on a world characterized by random eruptions of violence and chaotic disturbances emanating from undefined and unacknowledged human motivations and impulses. From the constant authorial presence manifested in early novels, Hawkes becomes concerned, in his first-person narratives, with filtering a sense of authoritarian will through the visions of narrators who are intent on shaping their own worlds and utilizing the energies of the unconscious and their imaginative capacity. The artist comes to define himself through his thorough isolation from others and from external reality: his quest is for an artistic purity to which he obsessively dedicates himself.;As the worlds of these artists become more confining, they also become more problematical. Many of the concerns of the visionary artist reflect Hawkes\u27 own fictional values. In novels like Travesty and Virginie Hawkes seems to be testing these values, exploring the ultimate reaches of a fictional aesthetic he has consistently expressed in interviews and essays throughout his career

Monitoring transfected cells without selection agents by using the dual-cassette expression EGFP vectors

Conventional methods of selecting gene transfected cells by toxic agents may yield ambiguous results. It is difficult to determine whether cell death is due to selection agents or gene transfection, owing to the substantial overlap of the time-courses for both effects. Therefore, to determine transfection-induced cell toxicity, the mammalian expression vector pEGFP-N1 (CLONTECH Lab., Palo Alto, CA, USA) has been modified to the dual-cassette expression vectors named pEGFP-Ks by the relocation of its EGFP expression cassette. We have precisely monitored the cells transfected with this vector on our custom culture dishes, thereby bypassing the need for selection agent or fluorescent cell sorting. This is a useful method to screen genes encoding potential toxic or useful proteins without performing undesirable selection agent and also can be used to monitor the transfected cells for various purposes, either the inhibition or proliferation of mammalian cells for applications in biotechnology

The cohomology of real De Concini-Procesi models of Coxeter type

We study the rational cohomology groups of the real De Concini-Procesi model corresponding to a finite Coxeter group, generalizing the type-A case of the moduli space of stable genus 0 curves with marked points. We compute the Betti numbers in the exceptional types, and give formulae for them in types B and D. We give a generating-function formula for the characters of the representations of a Coxeter group of type B on the rational cohomology groups of the corresponding real De Concini-Procesi model, and deduce the multiplicities of one-dimensional characters in the representations, and a formula for the Euler character. We also give a moduli space interpretation of this type-B variety, and hence show that the action of the Coxeter group extends to a slightly larger group.Comment: 27 pages. The main change in Version 2 is a type-independent proof of Cohen-Macaulaynes

Ultrastructural characterization of colloidal metal films for bioanalytical applications by scanning force microscopy

Colloidal metal films (CMFs) are prepared by the attachment of silver, gold, or platinum (or other metal) particles to a glass slide modified by silanization with 3‐mercaptopropyl silane. The covalent attachment of the metal particles occurs through the metal–sulfur bond. In these samples the local electromagnetic field is enhanced near the surface of the CMF due to excitation of plasmon resonances. This phenomenon can be used for a variety of analytical applications. Because the optical properties are strongly dependent on the morphology of the film, its structural characterization becomes of great importance. To further characterize CMFs we have used scanning force microscopy (SFM). Initial studies revealed lateral dimensions of the particles as well as the particle density. Height measurements were made using the three‐dimensional topographic image of the surface yielded by SFM, and were used to evaluate the selective deposition of a silica spacer layer onto the metal particles. Comparative SFM measurements in water and air using different imaging modes were performed to investigate the mechanical stability of CMFs against the forces exerted by the scanning tip