Institution

# University of Cambridge

Education•Cambridge, United Kingdom•

About: University of Cambridge is a(n) education organization based out in Cambridge, United Kingdom. It is known for research contribution in the topic(s): Population & Galaxy. The organization has 118293 authors who have published 282289 publication(s) receiving 14497093 citation(s). The organization is also known as: Cambridge University & Cambridge.

Topics: Population, Galaxy, Transplantation, Redshift, Gene

##### Papers

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TL;DR: The PHENIX software for macromolecular structure determination is described and its uses and benefits are described.

Abstract: Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. However, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallographic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a tight integration between the algorithms.

15,827 citations

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TL;DR: A description is given of Phaser-2.1: software for phasing macromolecular crystal structures by molecular replacement and single-wavelength anomalous dispersion phasing.

Abstract: Phaser is a program for phasing macromolecular crystal structures by both molecular replacement and experimental phasing methods. The novel phasing algorithms implemented in Phaser have been developed using maximum likelihood and multivariate statistics. For molecular replacement, the new algorithms have proved to be significantly better than traditional methods in discriminating correct solutions from noise, and for single-wavelength anomalous dispersion experimental phasing, the new algorithms, which account for correlations between F+ and F−, give better phases (lower mean phase error with respect to the phases given by the refined structure) than those that use mean F and anomalous differences ΔF. One of the design concepts of Phaser was that it be capable of a high degree of automation. To this end, Phaser (written in C++) can be called directly from Python, although it can also be called using traditional CCP4 keyword-style input. Phaser is a platform for future development of improved phasing methods and their release, including source code, to the crystallographic community.

15,505 citations

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Lawrence Berkeley National Laboratory

^{1}, University of California, Berkeley^{2}, Instituto Superior Técnico^{3}, Pierre-and-Marie-Curie University^{4}, Stockholm University^{5}, European Southern Observatory^{6}, Collège de France^{7}, University of Cambridge^{8}, University of Barcelona^{9}, Yale University^{10}, Space Telescope Science Institute^{11}, European Space Agency^{12}, University of New South Wales^{13}Abstract: We report measurements of the mass density, Omega_M, and
cosmological-constant energy density, Omega_Lambda, of the universe based on
the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology
Project. The magnitude-redshift data for these SNe, at redshifts between 0.18
and 0.83, are fit jointly with a set of SNe from the Calan/Tololo Supernova
Survey, at redshifts below 0.1, to yield values for the cosmological
parameters. All SN peak magnitudes are standardized using a SN Ia lightcurve
width-luminosity relation. The measurement yields a joint probability
distribution of the cosmological parameters that is approximated by the
relation 0.8 Omega_M - 0.6 Omega_Lambda ~= -0.2 +/- 0.1 in the region of
interest (Omega_M <~ 1.5). For a flat (Omega_M + Omega_Lambda = 1) cosmology we
find Omega_M = 0.28{+0.09,-0.08} (1 sigma statistical) {+0.05,-0.04}
(identified systematics). The data are strongly inconsistent with a Lambda = 0
flat cosmology, the simplest inflationary universe model. An open, Lambda = 0
cosmology also does not fit the data well: the data indicate that the
cosmological constant is non-zero and positive, with a confidence of P(Lambda >
0) = 99%, including the identified systematic uncertainties. The best-fit age
of the universe relative to the Hubble time is t_0 = 14.9{+1.4,-1.1} (0.63/h)
Gyr for a flat cosmology. The size of our sample allows us to perform a variety
of statistical tests to check for possible systematic errors and biases. We
find no significant differences in either the host reddening distribution or
Malmquist bias between the low-redshift Calan/Tololo sample and our
high-redshift sample. The conclusions are robust whether or not a
width-luminosity relation is used to standardize the SN peak magnitudes.

15,392 citations

14

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University of Cambridge

^{1}, Max Planck Society^{2}, IPG Photonics^{3}, University of Manchester^{4}TL;DR: This work shows that graphene's electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers, and allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.

Abstract: Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process The G peak slightly down-shifts This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area

12,229 citations

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Abstract: This paper proposes unit root tests for dynamic heterogeneous panels based on the mean of individual unit root statistics. In particular it proposes a standardized t-bar test statistic based on the (augmented) Dickey–Fuller statistics averaged across the groups. Under a general setting this statistic is shown to converge in probability to a standard normal variate sequentially with T (the time series dimension) →∞, followed by N (the cross sectional dimension) →∞. A diagonal convergence result with T and N→∞ while N/T→k, k being a finite non-negative constant, is also conjectured. In the special case where errors in individual Dickey–Fuller (DF) regressions are serially uncorrelated a modified version of the standardized t-bar statistic is shown to be distributed as standard normal as N→∞ for a fixed T, so long as T>5 in the case of DF regressions with intercepts and T>6 in the case of DF regressions with intercepts and linear time trends. An exact fixed N and T test is also developed using the simple average of the DF statistics. Monte Carlo results show that if a large enough lag order is selected for the underlying ADF regressions, then the small sample performances of the t-bar test is reasonably satisfactory and generally better than the test proposed by Levin and Lin (Unpublished manuscript, University of California, San Diego, 1993).

11,149 citations

##### Authors

Showing all 118293 results

Name | H-index | Papers | Citations |
---|---|---|---|

Albert Hofman | 267 | 2530 | 321405 |

Zhong Lin Wang | 245 | 2529 | 259003 |

Solomon H. Snyder | 232 | 1222 | 200444 |

Trevor W. Robbins | 231 | 1137 | 164437 |

George Davey Smith | 224 | 2540 | 248373 |

Nicholas J. Wareham | 212 | 1657 | 204896 |

Cyrus Cooper | 204 | 1869 | 206782 |

Eric B. Rimm | 196 | 988 | 147119 |

Martin White | 196 | 2038 | 232387 |

Simon D. M. White | 189 | 795 | 231645 |

Michael Rutter | 188 | 676 | 151592 |

George Efstathiou | 187 | 637 | 156228 |

Mark Hallett | 186 | 1170 | 123741 |

David H. Weinberg | 183 | 700 | 171424 |

Paul G. Richardson | 183 | 1533 | 155912 |