2,261 research outputs found

    Differential analysis of high-throughput quantitative genetic interaction data

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    Synthetic genetic arrays have been very effective at measuring genetic interactions in yeast in a high-throughput manner and recently have been expanded to measure quantitative changes in interaction, termed 'differential interactions', across multiple conditions. Here, we present a strategy that leverages statistical information from the experimental design to produce a novel, quantitative differential interaction score, which performs favorably compared to previous differential scores. We also discuss the added utility of differential genetic-similarity in differential network analysis. Our approach is preferred for differential network analysis, and our implementation, written in MATLAB, can be found at http://chianti.ucsd.edu/~gbean/compute_differential_scores.m

    On the growth of perturbations in interacting dark energy and dark matter fluids

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    The covariant generalizations of the background dark sector coupling suggested in G. Mangano, G. Miele and V. Pettorino, Mod. Phys. Lett. A 18, 831 (2003) are considered. The evolution of perturbations is studied with detailed attention to interaction rate that is proportional to the product of dark matter and dark energy densities. It is shown that some classes of models with coupling of this type do not suffer from early time instabilities in strong coupling regime.Comment: 11 pages, 2 figures. v3: minor changes, typos fixe

    Student Satisfaction and Performance in an Online Teacher Certification Program

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    The article presents a study which demonstrates the effectiveness of an online post baccalaureate teacher certification program developed by a Wisconsin university. The case method approach employing multiple methods and multiple data sources were used to investigate the degree to which pre-service teachers were prepared to teach. It was concluded that the study supports online delivery as an effective means of teacher preparation, but it was limited in the number of students followed into their first year of teaching

    Immigrant community integration in world cities

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    As a consequence of the accelerated globalization process, today major cities all over the world are characterized by an increasing multiculturalism. The integration of immigrant communities may be affected by social polarization and spatial segregation. How are these dynamics evolving over time? To what extent the different policies launched to tackle these problems are working? These are critical questions traditionally addressed by studies based on surveys and census data. Such sources are safe to avoid spurious biases, but the data collection becomes an intensive and rather expensive work. Here, we conduct a comprehensive study on immigrant integration in 53 world cities by introducing an innovative approach: an analysis of the spatio-temporal communication patterns of immigrant and local communities based on language detection in Twitter and on novel metrics of spatial integration. We quantify the "Power of Integration" of cities --their capacity to spatially integrate diverse cultures-- and characterize the relations between different cultures when acting as hosts or immigrants.Comment: 13 pages, 5 figures + Appendi

    A Review of the Tools Used for Marine Monitoring in the UK: Combining Historic and Contemporary Methods with Modeling and Socioeconomics to Fulfill Legislative Needs and Scientific Ambitions

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    Marine environmental monitoring is undertaken to provide evidence that environmental management targets are being met. Moreover, monitoring also provides context to marine science and over the last century has allowed development of a critical scientific understanding of the marine environment and the impacts that humans are having on it. The seas around the UK are currently monitored by targeted, impact-driven, programmes (e.g., fishery or pollution based monitoring) often using traditional techniques, many of which have not changed significantly since the early 1900s. The advent of a new wave of automated technology, in combination with changing political and economic circumstances, means that there is currently a strong drive to move toward a more refined, efficient, and effective way of monitoring. We describe the policy and scientific rationale for monitoring our seas, alongside a comprehensive description of the types of equipment and methodology currently used and the technologies that are likely to be used in the future. We contextualize the way new technologies and methodologies may impact monitoring and discuss how whole ecosystems models can give an integrated, comprehensive approach to impact assessment. Furthermore, we discuss how an understanding of the value of each data point is crucial to assess the true costs and benefits to society of a marine monitoring programme

    Planck 2013 results. XXII. Constraints on inflation

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    We analyse the implications of the Planck data for cosmic inflation. The Planck nominal mission temperature anisotropy measurements, combined with the WMAP large-angle polarization, constrain the scalar spectral index to be ns = 0:9603 _ 0:0073, ruling out exact scale invariance at over 5_: Planck establishes an upper bound on the tensor-to-scalar ratio of r < 0:11 (95% CL). The Planck data thus shrink the space of allowed standard inflationary models, preferring potentials with V00 < 0. Exponential potential models, the simplest hybrid inflationary models, and monomial potential models of degree n _ 2 do not provide a good fit to the data. Planck does not find statistically significant running of the scalar spectral index, obtaining dns=dln k = 0:0134 _ 0:0090. We verify these conclusions through a numerical analysis, which makes no slowroll approximation, and carry out a Bayesian parameter estimation and model-selection analysis for a number of inflationary models including monomial, natural, and hilltop potentials. For each model, we present the Planck constraints on the parameters of the potential and explore several possibilities for the post-inflationary entropy generation epoch, thus obtaining nontrivial data-driven constraints. We also present a direct reconstruction of the observable range of the inflaton potential. Unless a quartic term is allowed in the potential, we find results consistent with second-order slow-roll predictions. We also investigate whether the primordial power spectrum contains any features. We find that models with a parameterized oscillatory feature improve the fit by __2 e_ _ 10; however, Bayesian evidence does not prefer these models. We constrain several single-field inflation models with generalized Lagrangians by combining power spectrum data with Planck bounds on fNL. Planck constrains with unprecedented accuracy the amplitude and possible correlation (with the adiabatic mode) of non-decaying isocurvature fluctuations. The fractional primordial contributions of cold dark matter (CDM) isocurvature modes of the types expected in the curvaton and axion scenarios have upper bounds of 0.25% and 3.9% (95% CL), respectively. In models with arbitrarily correlated CDM or neutrino isocurvature modes, an anticorrelated isocurvature component can improve the _2 e_ by approximately 4 as a result of slightly lowering the theoretical prediction for the ` <_ 40 multipoles relative to the higher multipoles. Nonetheless, the data are consistent with adiabatic initial conditions

    Intersectional Differences in Segmented Assimilation: Skill and Gender in the Context of Reception

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    Purpose - Segmented assimilation theory predicts that contemporary non-white groups follow three patterns of assimilation: mainstream, downward, or delayed. Yet, the homogenous treatment and primacy of ethnicity resigns all group members to a similar fate. Whereas few studies of ethnic incorporation consider both the classed and gendered nature of the labor market, this study investigates the extent to which intersectional group differences within the highly stratified American economy shape segmented assimilation trajectories. Methodology/approach - This study introduces an intersectional approach to segmented assimilation theory. Using the 2000 census, this study examines how within group differences in skill and gender condition the hourly earnings, joblessness and self-employment participation outcomes of five ethnic minority groups from the first to the second generation, compared against US-born, non-Hispanic whites.Findings - Findings generally support the mainstream assimilation hypothesis for all groups; a downward assimilation trajectory among Chinese men only; and a delayed assimilation trajectory for low-skilled Filipinas and high-skilled Cuban men and women. This study reveals that intra-group differences in skill and gender shape divergent segmented assimilation trajectories among members of the same ethnic group. Originality/value - This study challenges the emphasis on and primacy of ethnicity in predicting segmented assimilation in favor of an intersectional approach that considers how multiple, interdependent, and intersecting dimensions of identity and not only ethnicity shape the process of economic incorporation among ethnic groups

    Probing BFKL Dynamics in the Dijet Cross Section at Large Rapidity Intervals in ppbar Collisions at sqrt{s}=1800 and 630 GeV

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    Inclusive dijet production at large pseudorapidity intervals (delta_eta) between the two jets has been suggested as a regime for observing BFKL dynamics. We have measured the dijet cross section for large delta_eta in ppbar collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic cross section increases strongly with the size of delta_eta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of a_{BFKL}(20GeV)=1.65+/-0.07.Comment: Published in Physical Review Letter

    Search for Electroweak Production of Single Top Quarks in ppbar Collisions

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    We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb.Comment: 11 pages, 2 figures. This is the published versio

    Spin Correlation in tt-bar Production from pp-bar Collisions at sqrt(s)=1.8 TeV

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    The D0 collaboration has performed a study of spin correlation in tt-bar production for the process tt-bar to bb-bar W^+W^-, where the W bosons decay to e-nu or mu-nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb^-1 of sqrt{s}=1.8 TeV pp-bar collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the tt-bar decay products. The degree of spin correlation is characterized by a correlation coefficient k. We find that k>-0.25 at the 68% confidence level, in agreement with the SM prediction of k=0.88.Comment: Submitted to PRL, Added references, minor changes to tex
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