10,541 research outputs found
Lyman break galaxies and the star formation rate of the Universe at z ~ 6
No full textWe determine the space density of UV-luminous starburst galaxies at z≈ 6 using deep HST ACS SDSS-i′ (F775W) and SDSS-z′ (F850LP) and VLT ISAAC J and Ks band imaging of the Chandra Deep Field South. We find eight galaxies and one star with (i′−z′) > 1.5 to a depth of z′AB= 25.6 (an 8σ detection in each of the 3 available ACS epochs). This corresponds to an unobscured star formation rate of ≈15 h−270 M⊙ yr−1 at z= 5.9, equivalent to L* for the Lyman-break population at z= 3–4 (ΩΛ= 0.7, ΩM= 0.3). We are sensitive to star-forming galaxies at 5.6 ≲z≲ 7.0 with an effective comoving volume of ≈1.8 × 105h−370 Mpc3 after accounting for incompleteness at the higher redshifts due to luminosity bias. This volume should encompass the primeval subgalactic-scale fragments of the progenitors of about a thousand L* galaxies at the current epoch. We determine a volume-averaged global star formation rate of (6.7 ± 2.7) × 10−4h70 M⊙ yr−1 Mpc−3 at z∼ 6 from rest-frame UV selected starbursts at the bright end of the luminosity function: this is a lower limit because of dust obscuration and galaxies below our sensitivity limit. This measurement shows that at z∼ 6 the star formation density at the bright end is a factor of ∼6 times less than that determined by Steidel et al. for a comparable sample of UV-selected galaxies at z= 3–4, and so extends our knowledge of the star formation history of the Universe to earlier times than previous work and into the epoch where reionization may have occurred
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
First observation of the decay Bs0→K*0K*0
No full textThe first observation of the decay B0s→K∗0K∗0 is reported using 35 pb−1 of data collected by LHCb in proton–proton collisions at a centre-of-mass energy of 7 TeV. A total of 49.8±7.5 B0s→(K+π−)(K−π+) events are observed within ±50 MeV/c2 of the B0s mass and 746 MeV/c2 < mKπ < 1046 MeV/c2, mostly coming from a resonant B0s→K∗0K∗0 signal. The branching fraction and the CP-averaged K∗0 longitudinal polarization fraction are measured to be B(B0s→K∗0K∗0)=(2.81±0.46(stat.)±0.45(syst.)±0.34(fs/ fd))×10−5 and fL =0.31±0.12(stat.)±0.04(syst.)
-actions with connected fixed point set
No full textIn this paper we describe the equivariant cobordism classification of smooth actions of the group on closed smooth
-dimensional manifolds , for which the fixed point set of the action is a connected manifold of dimension n and .
Here, is considered as the group generated by commuting smooth involutions defined on .
This generalizes a previous result of 2008 of the second author, who obtained this type of classification for and or
Self-archiving practice and the influence of publisher policies in the social sciences
No full textAuthors in different disciplines exhibit very different behaviours on the so-called ‘green’ road to open access, i.e. self-archiving. This study looks at the self-archiving behaviour of authors publishing in leading journals in six social science disciplines. It tests the hypothesis that authors are self-archiving according to the norms of their respective disciplines rather than following self-archiving policies of publishers, and that, as a result, they are self-archiving significant numbers of publisher PDF versions. It finds significant levels of
self-archiving, as well as significant self-archiving of
the publisher PDF version, in all the disciplines
investigated. Publishers’ self-archiving policies have
no influence on author self-archiving practice
K-theory for group C*-algebras
No full textThese notes are based on a lecture course given by the first author in the Sedano Winter School on K-theory held in Sedano, Spain, on January 22-27th of 2007. They aim at introducing K-theory of C*-algebras, equivariant K-homology and KK-theory in the context of the Baum-Connes conjectur
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
A deuterium NMR study of molecular dynamics and geometry in two classes of onium salts:(CH3) 3E+ X-and C6H5M (CH3) 3+ I
No full textDeuterium NMR measurements are reported for two types of onium salts: (CH3)3E+I-, where E = O (counterion is BF4-), S, Se, or Te, and C6H5M(CH3)3+I-, where M = N, P, or As. Within each class of compounds the activation energy for rotation of the trimethyl groups about the C3' axis increases with increasing size of the central atom. In the first class of compounds the C-E-C bond angle decreases with the size of the atom E. In addition the magnitude of the quadrupolar coupling constant, chi, varies with E, ranging from 160 kHz for E = O to 190 kHz for E = Te. This is in qualitative agreement with molecular orbital calculations of the electric field gradients. At low temperatures the H-2 NMR spectrum of C6H5N(CH3)3+I- Can only be rationalized with a model in which trimethyl rotation is faster than methyl rotation. The H-2 NMR of ring (predominantly ortho and para)-deuterated C6H5N(CH3)3+I- is consistent with rapid n-site (n greater-than-or-equal-to 3) rotation of the phenyl ring above 390 K. Below 390 K spectra characteristic of two-site, 180-degrees, flips of the phenyl ring are observed. Below 280 K the motion of the phenyl ring is in the rigid lattice limit.PT: J; CR: COLLINS MJ, 1988, J AM CHEM SOC, V110, P8583 DAVIS JH, 1976, CHEM PHYS LETT, V42, P390 DAVIS JH, 1991, ISOTOPES PHYSICAL BI, V3 EINSTEIN F, 1967, J CHEM SOC A, P2018 FECHER G, 1986, BER BUNSEN PHYS CHEM, V90, P10 FISCH MJ, 1990, GAUSSIAN 90 FURUKAWA Y, 1989, Z NATURFORSCH A, V44, P112 GREENFIELD MS, 1987, J MAGN RESON, V72, P89 GRIFFIN RG, 1981, METHOD ENZYMOL, V72, P108 GRUWEL MLH, 1990, Z NATURFORSCH A, V45, P55 HAYS GR, 1978, THESIS U E ANGLIA HIROKAWA K, 1988, Z NATURFORSCH A, V43, P187 HOPE H, 1966, ACTA CRYSTALLOGR, V20, P610 IKEDA R, 1989, J PHYS CHEM-US, V93, P7315 ISHIDA H, 1989, Z NATURFORSCH A, V44, P741 ISHIDA H, 1991, Z NATURFORSCH A, V46, P265 KOBAYASHI A, 1988, Z NATURFORSCH A, V43, P233 KORFER M, 1989, Z NATURFORSCH A, V44, P1177 KRUG V, 1989, ACTA CRYSTALLOGR C, V45, P2022 LAMBERT JB, 1968, J AM CHEM SOC, V90, P1349 MANTSCH HH, 1977, PROG NUCL MAG RES SP, V11, P211 MOOIBROEK S, 1988, CAN J CHEM, V66, P734 MOOIBROEK S, 1989, CAN J CHEM, V63, P2926 OLAH GA, 1984, J ORG CHEM, V49, P2112 PALMER MH, 1986, Z NATURFORSCH A, V41, P1471 PALMER MH, 1990, Z NATURFORSCH A, V45, P357 PENNER GH, 1992, CAN J CHEM, V70, P2420 PENNER GH, 1992, J PHYS CHEM-US, V96, P5121 PETTITT BA, 1981, J MAGN RESON, V44, P508 RATCLIFFE CI, 1979, FARADAY DISC CHEM SO, V13, P142 RATCLIFFE CI, 1986, CAN J CHEM, V64, P1348 RATCLIFFE CI, 1990, J PHYS CHEM-US, V94, P152 RIPMEESTER JA, 1987, DYNAMICS MOL CRYSTAL SCHWARTZ LJ, 1983, J PHYS CHEM-US, V87, P4457 SPIESS HW, 1985, ADV POLYM SCI, V66, P23 THOMAS AF, 1971, DEUTERIUM LABELING O TSAU J, 1970, CAN J CHEM, V48, P717 VEGA AJ, 1987, J CHEM PHYS, V86, P1803 WATKINS MI, 1982, J AM CHEM SOC, V104, P2365 WITTEBORT RJ, 1987, J CHEM PHYS, V86, P5411 XU Q, 1991, Z NATURFORSCH A, V46, P240 ZUCCARO DE, 1959, Z KRISTALLOGR, V112, P26; NR: 42; TC: 6; J9: CAN J CHEM; PG: 10; GA: LC512Source type: Electronic(1
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