This research examines the relationship between social control and social learning variables on involvement in violent vs. non-violent extremism. Using data from the Profiles of Individual ...Radicalization in the United States (PIRUS) database (n = 1,757), this study presents a series of logistic regressions. Among radicalized individuals, weaker social control and stronger social learning of violence were associated violent over non-violent behavior. These results hold across all models. Taken together, these findings support the role of control and learning theories in identifying correlates of violent and non-violent extremism and suggest the possibility of reciprocal and interaction effects for future work.
Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical ...processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α'/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.
As nascent polypeptides exit ribosomes, they are engaged by a series of processing, targeting, and folding factors. Here, we present a selective ribosome profiling strategy that enables global ...monitoring of when these factors engage polypeptides in the complex cellular environment. Studies of the
Escherichia coli chaperone trigger factor (TF) reveal that, though TF can interact with many polypeptides, β-barrel outer-membrane proteins are the most prominent substrates. Loss of TF leads to broad outer-membrane defects and premature, cotranslational protein translocation. Whereas in vitro studies suggested that TF is prebound to ribosomes waiting for polypeptides to emerge from the exit channel, we find that in vivo TF engages ribosomes only after ∼100 amino acids are translated. Moreover, excess TF interferes with cotranslational removal of the N-terminal formyl methionine. Our studies support a triaging model in which proper protein biogenesis relies on the fine-tuned, sequential engagement of processing, targeting, and folding factors.
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► Ribosome profiling broadly enables quantitative analysis of translation in bacteria ► Selective ribosome profiling reveals cotranslational chaperone action of trigger factor ► Trigger factor engages nascent chains only after ∼100 residues have been translated ► Outer-membrane porins are highly enriched among trigger factor substrates
Ribosome profiling offers a dynamic view of a chaperone's engagement with nascent polypeptides, yielding insights into its selective activity that have been opaque to more traditional biochemical and genetic analyses.
How nascent polypeptides emerging from ribosomes fold into functional structures is poorly understood. Here, we monitor disulfide bond formation, protease resistance, and enzymatic activity in ...nascent polypeptides to show that in close proximity to the ribosome, conformational space and kinetics of folding are restricted. Folding constraints decrease incrementally with distance from the ribosome surface. Upon ribosome binding, the chaperone Trigger Factor counters folding also of longer nascent chains, to extents varying between different chain segments. Trigger Factor even binds and unfolds pre-existing folded structures, the unfolding activity being limited by the thermodynamic stability of nascent chains. Folding retardation and unfolding activities are not shared by the DnaK chaperone assisting later folding steps. These ribosome- and Trigger Factor-specific activities together constitute an efficient mechanism to prevent or even revert premature folding, effectively limiting misfolded intermediates during protein synthesis.
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► Nascent polypeptide folding is constrained by ribosome proximity or Trigger Factor ► The influence of Trigger Factor varies for different segments of nascent chains ► Trigger Factor unfolds prefolded domains and rescues folding intermediates ► Unfolding activity is Trigger Factor specific and not shared by other chaperones
ABSTRACT We present the discovery of nine quasars at identified in the Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey of quasars in the SDSS footprint. Our final sample ...consists of 52 quasars at , including 29 quasars with mag selected from 11,240 deg2 of the SDSS single-epoch imaging survey (the main survey), 10 quasars with selected from 4223 deg2 of the SDSS overlap regions (regions with two or more imaging scans), and 13 quasars down to mag from the 277 deg2 in Stripe 82. They span a wide luminosity range of . This well-defined sample is used to derive the quasar luminosity function (QLF) at . After combining our SDSS sample with two faint ( mag) quasars from the literature, we obtain the parameters for a double power-law fit to the QLF. The bright-end slope β of the QLF is well constrained to be . Due to the small number of low-luminosity quasars, the faint-end slope and the characteristic magnitude are less well constrained, with and mag. The spatial density of luminous quasars, parametrized as , drops rapidly from to 6, with . Based on our fitted QLF and assuming an intergalactic medium (IGM) clumping factor of C = 3, we find that the observed quasar population cannot provide enough photons to ionize the IGM at ∼90% confidence. Quasars may still provide a significant fraction of the required photons, although much larger samples of faint quasars are needed for more stringent constraints on the quasar contribution to reionization.
Telomere length is associated with cellular senescence, lifestyle and ageing. Short telomeres indicate poor health in humans and reduced life expectancy in several bird species, but little is known ...about telomeres in relation to phenotypic quality in wild animals. We investigated telomere lengths in erythrocytes of known-age common terns (Sterna hirundo), a migratory seabird, in relation to arrival date and reproductive performance. Cross-sectional data revealed that, independent of age, individuals with short telomeres performed better: they arrived and reproduced earlier in the season and had more chicks in the nest. The latter effect was stronger the older the brood and stronger in males, which do most of the chick provisioning. Longitudinal data confirmed this pattern: compared with birds that lost their brood, birds that raised chicks beyond the 10th nestling day experienced higher telomere attrition from one year to the next. However, more detailed analysis revealed that the least and most successful individuals lost the fewest base pairs compared with birds with intermediate success. Our results suggest that reproductive success is achieved at the expense of telomeres, but that individual heterogeneity in susceptibility to such detrimental effects is important, as indicated by low telomere loss in the most successful birds.
Purpose
This systematic review summarises the literature on patient selection, decision-making, effectiveness and outcomes in the surgical treatment of lumbar degenerative spondylolisthesis (LDS).
...Introduction
In daily practice, decision-making in the treatment of LDS is challenging. There is little consensus on either the precise indications or prognostic factors for any specific therapy (operative or non-operative).
Methods
We searched for LDS trials published between 01.01.1990 and 16.11.2011 in Medline, Embase, Cochrane Library and Cinahl. Two independent reviewers selected studies according to the inclusion criteria. Data were then extracted by two of the authors. Quality assessment was performed using the Downs and Black list for the clinical trials/studies and AMSTAR for the reviews.
Results
Data synthesis: 21 papers met the inclusion criteria (2 studies comprising both a RCT and a concurrent observational analysis, 1 RCT, 6 prospective studies, 8 retrospective studies, 3 reviews, 1 review guideline). The quality of the clinical studies was on average “fair” mean score 15.6 points (range 10–19) out of 24 points (Downs and Black). The quality of the reviews ranged from 1 to 7 out of 11 points with an average of 5 points (AMSTAR). The study outcomes could not be subject to meta-analysis due to heterogeneity of study design and variable measure used.
Conclusions
Despite there being many articles describing and/or comparing different surgical options for LDS, there was insufficient evidence to draw conclusions concerning clear indications for specific types of surgical treatment, predictors of outcome or complication rates. There remains a need to establish a decision-making tool to facilitate daily clinical practice and to assure appropriate treatment for patients with LDS.
The abundances of the highly siderophile elements (HSE) Re, Os, Ir, Ru, Pt, Rh, Pd and Au, and
187Os/
188Os isotope ratios have been determined for a set of carbonaceous, ordinary, enstatite and ...Rumuruti chondrites, using an analytical technique that permits the precise and accurate measurement of
all HSE from the same digestion aliquot. Concentrations of Re, Os, Ir, Ru, Pt and Pd were determined by isotope dilution ICP-MS and N-TIMS analysis. The monoisotopic elements Rh and Au were quantified relative to the abundance of Ir.
Differences in HSE abundances and ratios such as Re/Os,
187Os/
188Os, Pd/Ir and Au/Ir between different chondrite classes are further substantiated with new data, and additional Rh and Au data, including new data for CI chondrites. Systematically different relative abundances of Rh between different chondrite classes are reminiscent of the behaviour of Re. Carbonaceous chondrites are characterized by low average Rh/Ir of 0.27
±
0.03 (1s) which is about 20% lower than the ratio for ordinary (0.34
±
0.02) and enstatite chondrites (EH: 0.33
±
0.01; EL: 0.32
±
0.01). R chondrites show higher and somewhat variable Rh/Ir of 0.37
±
0.07.
Well-defined linear correlations of HSE, in particular for bulk samples of ordinary and EL chondrites, are explained by binary mixing and/or dilution by silicates. The HSE carriers responsible for these correlations have a uniform chemical composition, indicating efficient homogenization of local nebular heterogeneities during or prior to the formation of the host minerals in chondrite components. Excepting Rumuruti chondrites and Au in carbonaceous chondrites, these correlations also suggest that metamorphism, alteration and igneous processes had negligible influence on the HSE distribution on the bulk sample scale.
Depletion patterns for Rh, Pd and Au in carbonaceous chondrites other than CI are smoothly related to condensation temperatures and therefore consistent with the general depletion of moderately volatile elements in carbonaceous chondrites. Fractionated HSE abundance patterns of ordinary, enstatite and Rumuruti chondrites, however, are more difficult to explain. Fractional condensation combined with the removal of metal phases at various times, and later mixing of early and late formed metal phases may provide a viable explanation. Planetary fractionation processes that may have affected precursor material of chondrite components cannot explain the HSE abundance patterns of chondrite groups. HSE abundances of some, but not all Rumuruti chondrites may be consistent with solid sulphide–liquid sulphide fractionation processes during impact induced melting.
We present Hubble Space Telescope ACS images of 13 dust-reddened type 1 quasars selected from the FIRST/2MASS Red Quasar Survey. These quasars have high intrinsic luminosities after correction for ...dust obscuration (-23.5 greater than or equal to M sub(B) greater than or equal to -26.2 from K-magnitude). The images show strong evidence of recent or ongoing interaction in 11 of the 13 cases, even before the quasar nucleus is subtracted. None of the host galaxies are well fit by a simple elliptical profile. The fraction of quasars showing interaction is significantly higher than the 30% seen in samples of host galaxies of normal, unobscured quasars. There is a weak correlation between the amount of dust reddening and the magnitude of interaction In the host galaxy, measured using the Gini coefficient and the concentration index. Although few host galaxy studies of normal quasars are matched to ours in intrinsic quasar luminosity, no evidence has been found for a strong dependence of merger activity on host luminosity in samples of the host galaxies of normal quasars. We thus belleve that the high merger fraction in our sample is related to their obscured nature, with a significant amount of reddening occurring in the host galaxy. The red quasar phenomenon seems to have an evolutionary explanation, with the young quasar spending the early part of its lifetime enshrouded in an interacting galaxy. This might be further indication of a link between AGNs and starburst galaxies.
Co-translational mechanisms of protein maturation Gloge, Felix; Becker, Annemarie H; Kramer, Günter ...
Current opinion in structural biology,
February 2014, 2014-Feb, 2014-02-00, 20140201, Letnik:
24
Journal Article
Recenzirano
•Co-translational folding is influenced by translational pausing mechanisms.•The ribosome is providing a folding environment for nascent chains.•Action of nascent chain maturation factors is ...coordinated with translation.
Protein biogenesis integrates multiple finely regulated mechanisms, ensuring nascent polypeptide chains are correctly enzymatically processed, targeted to membranes and folded to native structure. Recent studies show that the cellular translation machinery serves as hub that coordinates the maturation events in space and time at various levels. The ribosome itself serves as docking site for a multitude of nascent chain-interacting factors. The movement of ribosomes along open reading frames is non-uniformous and includes pausing sites, which facilitates nascent chain folding and perhaps factor engagement. Here we summarize current knowledge and discuss emerging concepts underlying the critical interplay between translation and protein maturation in E. coli.
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