Lattice results for D/Ds leptonic and semileptonic decays

This review article summarizes recent lattice QCD results for D and D_s meson leptonic and semileptonic decays. Knowing the meson decay constants and semileptonic form factors from theory, one can extract CKM elements V_cd and V_cs from experimental results. At present, the most accurate results for decay constants are from the Fermilab Lattice and MILC Collaborations: f_D=212.5±0.5_{stat}+0.6−1.5|_{syst} MeV and fDs=248.9±0.2_{stat}+0.5−1.6|_{syst} MeV, giving V_cd=0.2184±0.009_{expt}+0.0008−0.0016|_{lattice} and V_cs=1.017±0.02_{expt}+0.002−0.007|_{lattice}. The shapes of the semileptonic form factors from lattice QCD agree very well with experiment, and the accuracy is currently at the 2-5% level for D→πℓν and 1-2% for D→Kℓν. Extracting the CKM elements from the semileptonic decays yields V_cd=0.225(6)_{expt}(10)_{lattice} (HPQCD Collaboration) and V_cs=0.963(5)_{expt}(14)_{lattice} (HPQCD Collaboration). These lattice calculations also revealed that the semileptonic form factors are insensitive to whether the spectator quark is a light or strange quark

Bryophyte flora of Western Melanesia

A project dealing with the hepatic and moss floras of New Guinea and the Solomon Islands has proceeded more than halfway. The revision of the flora is based on the study of ca 17000 specimens collected in 1981. Two new genera and ca 50 new species have been described in 33 published papers and seven manuscripts. Many families, genera and species not previously recorded for the area have been added to the flora. More than 300 names have been reduced to synonyms. The percentage of endemic species of liverworts (40 %) is higher than that of mosses (18 %). Most of the endemic species occur at elevations above 1700 m. The geological history of New Guinea suggests that these high altitude endemics may be relatively young, i.e. less than 10 million years old. The moss flora is more closely related to the floras of Indonesia and the Philippines and continental Asia than to that of Australia. This can be explained by plate tectonics. The altitudinal distribution of hepatic and moss floras partly coincides with the zonation of vegetation proposed earlier. Human influence on bryophyte floras is devastating but a part of the flora may survive in gardens and plantations

Ground-living spiders (Araneae) at polluted sites in the Subarctic

Spiders were studied around the Pechenganikel smelter combine, Kola Peninsula, north-western Russia. The average spider density was 6-fold greater and the density of Linyphiidae specimens 11.5-fold higher at slightly polluted sites, compared with heavily polluted sites. Altogether, 18 species from 10 families were found at heavily polluted sites, the theridiid Robertus scoticus clearly dominating (23.3 % of identifiable specimens), also Neon reticulatus (9.6 %), Thanatus formicinus (9.6 %) and Xysticus audax (8.2 %) were abundant. The most numerous among 58 species found at slightly polluted sites were Tapinocyba pallens (18.5 %), Robertus scoticus (13.7 %), Maso sundevalli (9.5 %) and Alopecosa aculeata (8.2 %). The family Linyphiidae dominated at slightly polluted sites, 64 % of species and 60 % of individuals; compared with heavily polluted sites, 23 % and 38 % respectively

Binary simple homogeneous structures are supersimple with finite rank

Suppose that M is an infinite structure with finite relational vocabulary such that every relation symbol has arity at most 2. If M is simple and homogeneous then its complete theory is supersimple with finite SU-rank which cannot exceed the number of complete 2-types over the empty set

A limit law of almost ll-partite graphs

For integers $l \geq 2$, $d \geq 1$ we study (undirected) graphs with vertices $1, ..., n$ such that the vertices can be partitioned into $l$ parts such that every vertex has at most $d$ neighbours in its own part. The set of all such graphs is denoted \mbP_n(l,d). We prove a labelled first-order limit law, i.e., for every first-order sentence $\varphi$, the proportion of graphs in \mbP_n(l,d) that satisfy $\varphi$ converges as $n \to \infty$. By combining this result with a result of Hundack, Pr\"omel and Steger \cite{HPS} we also prove that if $1 \leq s_1 \leq ... \leq s_l$ are integers, then \mb{Forb}(\mcK_{1, s_1, ..., s_l}) has a labelled first-order limit law, where \mb{Forb}(\mcK_{1, s_1, ..., s_l}) denotes the set of all graphs with vertices $1, ..., n$, for some $n$, in which there is no subgraph isomorphic to the complete $(l+1)$-partite graph with parts of sizes $1, s_1, ..., s_l$. In the course of doing this we also prove that there exists a first-order formula $\xi$ (depending only on $l$ and $d$) such that the proportion of \mcG \in \mbP_n(l,d) with the following property approaches 1 as $n \to \infty$: there is a unique partition of $\{1, ..., n\}$ into $l$ parts such that every vertex has at most $d$ neighbours in its own part, and this partition, viewed as an equivalence relation, is defined by $\xi$

Random graphs with bounded maximum degree: asymptotic structure and a logical limit law

For any fixed integer $R \geq 2$ we characterise the typical structure of undirected graphs with vertices $1, ..., n$ and maximum degree $R$, as $n$ tends to infinity. The information is used to prove that such graphs satisfy a labelled limit law for first-order logic. If $R \geq 5$ then also an unlabelled limit law holds