3,885 research outputs found
A Mixed Methods Empirical Examination of Changes in Emphasis and Style in the Extremist Magazines Dabiq and Rumiyah
The change in name of ISIS’s flagship English language magazine from Dabiq to Rumiyah prompted media speculation about its significance. This article uses a mixed methods approach that integrates a qualitative social semiotic discourse analysis approach with quantitative methods of information visualisation to examine empirically changes in emphasis and approach in both magazines over time to determine whether the changes are ones of style or substance. The paper argues that, while ISIS has changed its strategic focus over time in response to its changing fortunes, the organisation’s underlying world view, values and ultimate aims remain consistent and unchanged
An Arabidopsis mutant disrupted in valine catabolism is also compromised in peroxisomal fatty acid β-oxidation
AbstractCharacterisation of the Arabidopsis dbr5 mutant, which was isolated on the basis of 2,4-dichlorophenoxybutyric acid (2,4-DB) resistance, revealed that it is disrupted in the CHY1 gene. CHY1 encodes a peroxisomal protein that is 43% identical to the mammalian β-hydroxyisobutryl-CoA hydrolase of valine catabolism. We show that 2,4-DB resistance and the associated sucrose dependent seedling growth are due to a large activity decrease of 3-ketoacyl-CoA thiolase, which is involved in peroxisomal fatty acid β-oxidation. 14C-feeding studies demonstrate that dbr5 and chy1 seedlings are reduced in valine catabolism. These data support the hypothesis that CHY1 plays a key role in peroxisomal valine catabolism and that disruption of this enzyme results in accumulation of a toxic intermediate, methacrylyl-CoA, that inhibits 3-ketoacyl-CoA thiolase activity and thus blocks peroxisomal β-oxidation. We also show that CHY1 is repressed in seedlings grown on sugars, which suggests that branched chain amino acid catabolism is transcriptionally regulated by nutritional status
The competitive NMDA antagonist CPP protects substantia nigra neurons from MPTP-induced degeneration in primates
Degeneration of nigrostriatal dopaminergic neurons is the primary histopathological feature of Parkinson's disease. The neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) induces a neurological syndrome in man and non-human primates very similar to idiopathic Parkinson's disease by selectively destroying dopaminergic nigrostriatal neurons. This gives rise to the hypothesis that Parkinson's disease may be caused by endogenous or environmental toxins. Endogenous excitatory amino acids (EAAs) such as L-glutamate could be involved in neurodegenerative disorders including Parkinson's disease. We report in this study that the competitive NMDA antagonist CPP (3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid) protects nigral tyrosine hydroxylase (TH) positive neurons from degeneration induced by systemic treatment with MPTP in common marmosets. This indicates that EAAs are involved in the pathophysiological cascade of MPTP-induced neuronal cell death and that EAA antagonists may offer a neuroprotective therapy for Parkinson's disease
Experimental investigation of ultracold atom-molecule collisions
Ultracold collisions between Cs atoms and Cs2 dimers in the electronic ground
state are observed in an optically trapped gas of atoms and molecules. The Cs2
molecules are formed in the triplet ground state by cw-photoassociation through
the outer well of the 0g-(P3/2) excited electronic state. Inelastic
atom-molecule collisions converting internal excitation into kinetic energy
lead to a loss of Cs2 molecules from the dipole trap. Rate coefficients are
determined for collisions involving Cs atoms in either the F=3 or F=4 hyperfine
ground state and Cs2 molecules in either highly vibrationally excited states
(v'=32-47) or in low vibrational states (v'=4-6) of the a ^3 Sigma_u^+ triplet
ground state. The rate coefficients beta ~10^{-10} cm^3/s are found to be
largely independent of the vibrational and rotational excitation indicating
unitary limited cross sections.Comment: 4 pages, 3 figures, submitted for publicatio
Natural Language Understanding and Multimodal Discourse Analysis for Interpreting Extremist Communications and the Re-Use of These Materials Online
This paper reports on a study that is part of a project which aims to develop a multimodal analytical approach for big data analytics, initially in the context of violent extremism. The findings reported here tested the application of natural language processing models to the text of a sample of articles from the online magazines Dabiq and Rumiyah, produced by the Islamic extremist organisation ISIS. For comparison, text of articles found by reverse image search software which re-used the lead images from the original articles in text which either reported on or opposed extremist activities was also analysed. The aim was to explore what insights the natural language processing models could provide to distinguish between texts produced as propaganda to incite violent extremism and texts which either reported on or opposed violent extremism. The results showed that some valuable insights can be gained from such an approach and that these results could be improved through integrating automated analyses with a theoretical approach with analysed language and images in their immediate and social contexts. Such an approach will inform the interpretation of results and will be used in training software so that stronger results can be achieved in the future
Government Partisanship, Labor Organization, and Macroeconomic Performance: A Corrigendum
Alvarez, Garrett and Lange (1991) used cross-national data panel data on the Organization for Economic Coordination and Development nations to show that countries with left governments and encompassing labor movements enjoyed superior economic performance. Here we show that the standard errors reported in that article are incorrect. Reestimation of the model using ordinary least squares and robust standard errors upholds the major finding of Alvarez, Garrett and Lange, regarding the political and institutional causes of economic growth but leaves the findings for unemployment and inflation open to question. We show that the model used by Alvarez, Garrett and Lange, feasible generalized least squares, cannot produce standard errors when the number of countries analyzed exceeds the length of the time period under analysis. Also, we argue that ordinary least squares with robust standard errors is superior to feasible generalized least square for typical cross-national panel studies
The external benefits of higher education
The private market benefits of education are widely studied at the micro level, although the magnitude of their macroeconomic impact is disputed. However, there are additional benefits of education, which are less well understood. In this paper the macroeconomic effects of external benefits of higher education are estimated using the “micro-to-macro” simulation approach. Two types of externalities are explored: technology spillovers and productivity spillovers in the labour market. These links are illustrated and the results suggest they could be very large. However, this is qualified by the dearth of microeconomic evidence, for which we hope to encourage further work
Predicting the response of a submillimeter bolometer to cosmic rays
Bolometers designed to detect. submillimeter radiation also respond to cosmic, gamma, and x rays. Because detectors cannot be fully shielded from such energy sources, it is necessary to understand the effect of a photon or cosmic-ray particle being absorbed. The resulting signal (known as a glitch) can then be removed from raw data. We present measurements using an Americium-241 gamma radiation source to irradiate a prototype bolometer for the High Frequency Instrument in the Planck Surveyor satellite. Our measurements showed no variation in response depending on where the radiation was absorbed, demonstrating that the bolometer absorber and thermistor thermalize quickly. The bolometer has previously been fully characterized both electrically and optically. We find that using optically measured time constants underestimates the time taken for the detector to recover from a radiation absorption event. However, a full thermal model for the bolometer, with parameters taken from electrical and optical measurements, provides accurate time constants. Slight deviations from the model were seen at high energies; these can be accounted for by use of an extended model
Stubborn Predictions in Primary Visual Cortex
Perceivers can use past experiences to make sense of ambiguous sensory signals. However, this may be inappropriate when the world changes and past experiences no longer predict what the future holds. Optimal learning models propose that observers decide whether to stick with or update their predictions by tracking the uncertainty or "precision" of their expectations. However, contrasting theories of prediction have argued that we are prone to misestimate uncertainty-leading to stubborn predictions that are difficult to dislodge. To compare these possibilities, we had participants learn novel perceptual predictions before using fMRI to record visual brain activity when predictive contingencies were disrupted-meaning that previously "expected" events become objectively improbable. Multivariate pattern analyses revealed that expected events continued to be decoded with greater fidelity from primary visual cortex, despite marked changes in the statistical structure of the environment, which rendered these expectations no longer valid. These results suggest that our perceptual systems do indeed form stubborn predictions even from short periods of learning-and more generally suggest that top-down expectations have the potential to help or hinder perceptual inference in bounded minds like ours
- …