848 research outputs found

    The 2dF Galaxy Redshift Survey: spectral types and luminosity functions

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    We describe the 2dF Galaxy Redshift Survey (2dFGRS) and the current status of the observations. In this exploratory paper, we apply a principal component analysis to a preliminary sample of 5869 galaxy spectra and use the two most significant components to split the sample into five spectral classes. These classes are defined by considering visual classifications of a subset of the 2dF spectra, and also by comparison with high-quality spectra of local galaxies. We calculate a luminosity function for each of the different classes and find that later-type galaxies have a fainter characteristic magnitude, and a steeper faint-end slope. For the whole sample we find M*=-19.7 (for Ω=1, H_0=100kms^-1Mpc^-1), α=-1.3, φ*=0.017. For class 1 (`early-type') we find M*=-19.6, α=-0.7, while for class 5 (`late-type') we find M*=-19.0, α=-1.7. The derived 2dF luminosity functions agree well with other recent luminosity function estimates

    A measurement of the cosmological mass density from clustering in the 2dF Galaxy Redshift Survey

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    The large-scale structure in the distribution of galaxies is thought to arise from the gravitational instability of small fluctuations in the initial density field of the Universe. A key test of this hypothesis is that forming superclusters of galaxies should generate a systematic infall of other galaxies. This would be evident in the pattern of recessional velocities, causing an anisotropy in the inferred spatial clustering of galaxies. Here we report a precise measurement of this clustering, using the redshifts of more than 141,000 galaxies from the two-degree-field (2dF) galaxy redshift survey. We determine the parameter β = Ω0.6/b = 0.43 +/- 0.07, where Ω is the total mass-density parameter of the Universe and b is a measure of the `bias' of the luminous galaxies in the survey. (Bias is the difference between the clustering of visible galaxies and of the total mass, most of which is dark.) Combined with the anisotropy of the cosmic microwave background, our results favour a low-density Universe with Ω ~ 0.3

    An integrated model for predicting KRAS dependency

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    The clinical approvals of KRAS G12C inhibitors have been a revolutionary advance in precision oncology, but response rates are often modest. To improve patient selection, we developed an integrated model to predict KRAS dependency. By integrating molecular profiles of a large panel of cell lines from the DEMETER2 dataset, we built a binary classifier to predict a tumor's KRAS dependency. Monte Carlo cross validation via ElasticNet within the training set was used to compare model performance and to tune parameters α and λ. The final model was then applied to the validation set. We validated the model with genetic depletion assays and an external dataset of lung cancer cells treated with a G12C inhibitor. We then applied the model to several Cancer Genome Atlas (TCGA) datasets. The final "K20" model contains 20 features, including expression of 19 genes and KRAS mutation status. In the validation cohort, K20 had an AUC of 0.94 and accurately predicted KRAS dependency in both mutant and KRAS wild-type cell lines following genetic depletion. It was also highly predictive across an external dataset of lung cancer lines treated with KRAS G12C inhibition. When applied to TCGA datasets, specific subpopulations such as the invasive subtype in colorectal cancer and copy number high pancreatic adenocarcinoma were predicted to have higher KRAS dependency. The K20 model has simple yet robust predictive capabilities that may provide a useful tool to select patients with KRAS mutant tumors that are most likely to respond to direct KRAS inhibitors

    Genetic determinants of cellular addiction to DNA polymerase theta

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    Polymerase theta (Pol θ, gene name Polq) is a widely conserved DNA polymerase that mediates a microhomology-mediated, error-prone, double strand break (DSB) repair pathway, referred to as Theta Mediated End Joining (TMEJ). Cells with homologous recombination deficiency are reliant on TMEJ for DSB repair. It is unknown whether deficiencies in other components of the DNA damage response (DDR) also result in Pol θ addiction. Here we use a CRISPR genetic screen to uncover 140 Polq synthetic lethal (PolqSL) genes, the majority of which were previously unknown. Functional analyses indicate that Pol θ/TMEJ addiction is associated with increased levels of replication-associated DSBs, regardless of the initial source of damage. We further demonstrate that approximately 30% of TCGA breast cancers have genetic alterations in PolqSL genes and exhibit genomic scars of Pol θ/TMEJ hyperactivity, thereby substantially expanding the subset of human cancers for which Pol θ inhibition represents a promising therapeutic strategy

    Reduction of visual complexity in dynamic graphs

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    Genetically variant human pluripotent stem cells selectively eliminate wild-type counterparts through YAP-mediated cell competition

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    The appearance of genetic changes in human pluripotent stem cells (hPSCs) presents a concern for their use in research and regenerative medicine. Variant hPSCs that harbor recurrent culture-acquired aneuploidies display growth advantages over wild-type diploid cells, but the mechanisms that yield a drift from predominantly wild-type to variant cell populations remain poorly understood. Here, we show that the dominance of variant clones in mosaic cultures is enhanced through competitive interactions that result in the elimination of wild-type cells. This elimination occurs through corralling and mechanical compression by faster-growing variants, causing a redistribution of F-actin and sequestration of yes-associated protein (YAP) in the cytoplasm that induces apoptosis in wild-type cells. YAP overexpression or promotion of YAP nuclear localization in wild-type cells alleviates their “loser” phenotype. Our results demonstrate that hPSC fate is coupled to mechanical cues imposed by neighboring cells and reveal that hijacking this mechanism allows variants to achieve clonal dominance in cultures

    Two phase 3, double-blind, placebo-controlled studies of the efficacy and safety of Astodrimer 1% Gel for the treatment of bacterial vaginosis

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    Objective Astodrimer is a dendrimer formulated in a vaginal gel to treat bacterial vaginosis (BV) and prevent recurrence. The objective of these studies was to confirm the efficacy and safety of Astodrimer 1 % Gel for treatment of BV. Study Design Women with bacterial vaginosis were randomized 1:1 to Astodrimer 1 % Gel (Study 1 conducted in the United States, N = 127; Study 2 conducted in the United States, Germany and Belgium, N = 128) or placebo gel (Study 1, N = 123; Study 2, N = 123) at a dose of 5 g vaginally once daily for 7 days. The primary endpoint was clinical cure, defined as i) absence of bacterial vaginosis vaginal discharge; ii) <20 % clue cells; and iii) negative whiff test at day 9–12. Secondary efficacy analyses included clinical cure at day 21–30. Other endpoints at days 9–12 and 21–30 included Nugent cure (Nugent score ≤3), absence of symptoms, and adverse events. The primary analysis in the modified intent-to-treat population used the Cochran Mantel Haenszel test stratified by analysis center with a two-sided significance level of α = .05. Results Astodrimer 1 % Gel was superior to placebo for the primary and selected secondary efficacy measures. Clinical cure rates at day 9–12 were 50.4 % (59/117) vs 16.5 % (19/115, P < .001) (Study 1) and 56.7 % (68/120) vs 21.4 % (25/117, P < .001) (Study 2) for astodrimer vs placebo. At day 21–30, clinical cure results showed a similar trend but the difference to placebo was not statistically significant. Nugent cure rates at day 9–12 were 12.8 % (15/117) vs 2.6 % (3/115, P = .004) (Study 1) and 13.3 % (16/120) vs 5.1 % (6/117, P = .030) (Study 2) for astodrimer vs placebo. A greater proportion of women receiving astodrimer reported absence of vaginal discharge and absence of vaginal odor at day 9–12 and day 21–30 compared with placebo. Adverse events were generally mild and self-limiting. For the combined studies, adverse events potentially related to treatment occurred in 14.7 % (37/252) of astodrimer patients vs 9.4 % (23/244) for placebo, including vulvovaginal candidiasis reported for 2.4 % (6/252) of astodrimer patients. Conclusion These results support a role for Astodrimer 1 % Gel as an effective, safe and well-tolerated treatment for women with bacterial vaginosis

    The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

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    Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

    Results of the Search for Strange Quark Matter and Q-balls with the SLIM Experiment

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    The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls, which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m^2 of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.Comment: 14 pages, 11 EPS figure

    Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players

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    Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a pre-participation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. 25 pre and 25 post-peak height velocity (PHV) elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test, re-test design was used to explore the within-subject inter-session reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90 – 1.01 in pre and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, Kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test, re-test comparison
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