Reversible DNA micro-patterning using the fluorous effect

We describe a new method for the immobilisation of DNA into defined patterns with sub-micron resolution, using the fluorous effect. The method is fully reversible via a simple solvent wash, allowing the patterning, regeneration and re-patterning of surfaces with no degradation in binding efficiency following multiple removal/attachment cycles of different DNA sequences

Properties of Low-Lying Heavy-Light Mesons

We present preliminary results for the B meson decay constant and masses of low-lying heavy-light mesons in the static limit. Calculations were performed on the lattice in the quenched approximation using multistate smearing functions generated from a Hamiltonian for a spinless relativistic quark. The 2S--1S and 1P--1S mass splittings are measured. Using the 1P--1S charmonium splitting to set the overall scale, the ground state decay constant, f_B, is 319 +- 11 (stat) MeV.Comment: 8 pages, 9 figures, UCLA/92/TEP/4

WEATHERING, RADIOGENIC ISOTOPES, AND MARINE RECORDS OF GLACIAL DYNAMICS

Glacial advance and retreat is related to numerous climate system feedbacks; yet, this dynamic glacial activity tends to erase its own terrestrial record. As a result, deep-sea sediments may be the best archives for studying past glacial processes. Interpretations of these archives depend on understanding terrestrial sources to the marine sediments. Systematic spatial variations in dissolved riverine and soil leachate Sr, Nd and Pb isotopes across an ~175 km transect from the Greenland Ice Sheet to the coast present an analog for temporal changes during glacial retreat. Specifically, the offset between dissolved (riverine or soil leachates) and bulk sediment (bedload or leached soil) isotopes is highest in young glacial sediments close to the ice sheet and approaches zero in 10 ky old glacial sediments at the coast. This difference is attributed to a transition from preferential chemical weathering of trace minerals and/or radiation damaged sites in freshly comminuted, ice-proximal sediments to predominant weathering of less radiogenic (Sr and Pb) and more radiogenic (Nd) isotopes from bulk major minerals in more extensively weathered coastal material. These isotopes are transported to the ocean where the residence time of Sr is too long to be an effective tracer of local or regional glacial processes; however, the short residence time of Pb makes it an excellent tracer of local chemical weathering processes and the intermediate residence time of Nd allows application to region studies. Data from IODP Sites 1302/3 (3550 m water depth) in the NW Atlantic illustrate that seawater Pb and Nd isotopes preserved in authigenic FeMn-oxide coatings respond dramatically to retreat of the Laurentide Ice Sheet during the penultimate glacial termination (T2; 135-129 ka) and to rapid variations during Dansgaard-Oeschger cycles. These data suggest deep-sea radiogenic isotopes preserve a more detailed record of the long term history of ice sheet dynamics than terrestrial proxies. The systematic variation in chemical weathering linked to ice sheet retreat and reflected in deep-sea isotope records may also help refine estimates of past and future carbon cycling and fluxes of nutrients and isotopes to the ocean associated with high latitude climate change

Exclusive semileptonic Bs→KℓνB_s\to K \ell \nu decays on the lattice

Semileptonic $B_s \to K \ell \nu$ decays provide an alternative $b$-decay channel to determine the CKM matrix element $|V_{ub}|$, and to obtain a $R$-ratio to investigate lepton-flavor-universality violations. Results for the CKM matrix element may also shed light on the discrepancies seen between analyses of inclusive or exclusive decays. We calculate the decay form factors using lattice QCD with domain-wall light quarks and a relativistic $b$-quark. We analyze data at three lattice spacings with unitary pion masses down to $268\,\mathrm{MeV}$. Our numerical results are interpolated/extrapolated to physical quark masses and to the continuum to obtain the vector and scalar form factors $f_+(q^2)$ and $f_0(q^2)$ with full error budgets at $q^2$ values spanning the range accessible in our simulations. We provide a possible explanation of tensions found between results for the form factor from different lattice collaborations. Model- and truncation-independent $z$-parameterization fits following a recently proposed Bayesian-inference approach extend our results to the entire allowed kinematic range. Our results can be combined with experimental measurements of $B_s \to D_s$ and $B_s\to K$ semileptonic decays to determine $|V_{ub}|=3.8(6)\times 10^{-3}$. The error is currently dominated by experiment. We compute differential branching fractions and two types of $R$ ratios, the one commonly used as well as a variant better suited to test lepton-flavor universality.Comment: Version accepted and published (Phys. Rev. D 107, 114512) 30 pages, 13 Figures, supplementary data fil