This introduction to quantum chromodynamics presents the basic concepts and calculations in a clear and didactic style accessible to those new to the field. Readers will find useful methods for ...obtaining numerical results, including pure gauge theory and quenched spectroscopy.
We present a lattice QCD study of Nπ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance N*(1440) resides in experiment. The study is based on the PACS-CS ensemble ...of gauge configurations with Nf=2+1 Wilson-clover dynamical fermions, mπ≃156 MeV and L≃2.9 fm. In addition to a number of qqq interpolating fields, we implement operators for Nπ in p-wave and Nσ in s-wave. In the center-of-momentum frame we find three eigenstates below 1.65 GeV. They are dominated by N(0), N(0)π(0)π(0) mixed with N(0)σ(0) and N(p)π(−p) with p≃2π/L, where momenta are given in parentheses. This is the first simulation where the expected multi-hadron states are found in this channel. The experimental Nπ phase shift would-in the approximation of purely elastic Nπ scattering-imply an additional eigenstate near the Roper mass mR≃1.43 GeV for our lattice size. We do not observe any such additional eigenstate, which indicates that Nπ elastic scattering alone does not render a low-lying Roper. Coupling with other channels, most notably with Nππ, seems to be important for generating the Roper resonance, reinforcing the notion that this state could be a dynamically generated resonance. Our results are in line with most of the previous lattice studies based just on qqq interpolators, which did not find a Roper eigenstate below 1.65 GeV. The study of the coupled-channel scattering including a three-particle decay Nππ remains a challenge.
Described is a facile, scalable route to access functional‐group‐rich gem‐difluoroalkenes. Using visible‐light‐activated catalysts in conjunction with an arsenal of carbon‐radical precursors, an ...array of trifluoromethyl‐substituted alkenes undergoes radical defluorinative alkylation. Nonstabilized primary, secondary, and tertiary radicals can be used to install functional groups in a convergent manner, which would otherwise be challenging by two‐electron pathways. The process readily extends to other perfluoroalkyl‐substituted alkenes. In addition, we report the development of an organotrifluoroborate reagent to expedite the synthesis of the requisite trifluoromethyl‐substituted alkene starting materials.
CF3 today, CF2 tomorrow: Described is a facile, scalable route to access functional‐group‐rich gem‐difluoroalkenes. Trifluoromethyl‐substituted alkenes readily undergo radical defluorinative alkylation using visible‐light‐activated catalysts and an arsenal of C‐radical precursors. Nonstabilized primary, secondary, and tertiary radicals can be used to install various functional groups. PC=photocatalyst.
Mindfulness describes a state of consciousness in which individuals attend to ongoing events and experiences in a receptive and non-judgmental way. The present research investigated the idea that ...mindfulness reduces emotional exhaustion and improves job satisfaction. The authors further suggest that these associations are mediated by the emotion regulation strategy of surface acting. Study 1 was a 5-day diary study with 219 employees and revealed that mindfulness negatively related to emotional exhaustion and positively related to job satisfaction at both the within- and the between-person levels. Both relationships were mediated by surface acting at both levels of analysis. Study 2 was an experimental field study, in which participants (N = 64) were randomly assigned to a self-training mindfulness intervention group or a control group. Results revealed that participants in the mindfulness intervention group experienced significantly less emotional exhaustion and more job satisfaction than participants in the control group. The causal effect of mindfulness self-training on emotional exhaustion was mediated by surface acting. Implications for using mindfulness and mindfulness training interventions in organizational research and practice are discussed in conclusion.
Photoredox catalysis has experienced a revitalized interest from the synthesis community during the past decade. For example, photoredox/Ni dual catalysis protocols have been developed to overcome ...several inherent limitations of palladium-catalyzed cross-couplings by invoking a single-electron transmetalation pathway. This Perspective highlights advances made by our laboratory since the inception of the photoredox/Ni cross-coupling of benzyltrifluoroborates with aryl bromides. In addition to broadening the scope of trifluoroborate coupling partners, research using readily oxidized hypervalent silicates as radical precursors that demonstrate functional group compatibility is highlighted. The pursuit of electrophilic coupling partners beyond (hetero)aryl bromides has also led to the incorporation of several new classes of C(sp2)-hybridized substrates into light-mediated cross-coupling. Advances to expand the radical toolbox by utilizing feedstock chemicals (e.g., aldehydes) to access radicals that were previously inaccessible from trifluoroborates and silicates are also emphasized. Additionally, several organic photocatalysts have been investigated as replacements for their expensive iridium- and ruthenium-based counterparts. Lastly, the net C–H functionalization of the radical partner in an effort to improve atom economy is presented. An underlying theme in all of these studies is the value of generating radicals in a catalytic manner, rather than stoichiometrically.
The
is an extraordinarily diverse and ancient group of bacteria. Previous attempts to infer its deep phylogeny have been plagued with methodological artefacts. To overcome this, we analyzed a dataset ...of 200 single-copy and conserved genes and employed diverse strategies to reduce compositional artefacts. Such strategies include using novel dataset-specific profile mixture models and recoding schemes, and removing sites, genes and taxa that are compositionally biased. We show that the
and
(both groups of intracellular parasites of eukaryotes) are not sisters to each other, but instead, the
has a derived position within the
. A synthesis of our results also leads to an updated proposal for the higher-level taxonomy of the
. Our robust consensus phylogeny will serve as a framework for future studies that aim to place mitochondria, and novel environmental diversity, within the
.
By exploiting the large body of genome data and the considerable progress in phylogenetic methodology, recent phylogenomic studies have provided new insights into the relationships among major ...eukaryotic groups. However, confident placement of the eukaryotic root remains a major challenge. This is due to the large evolutionary distance separating eukaryotes from their closest relatives, the Archaea, implying a weak phylogenetic signal and strong long-branch attraction artifacts. Here, we apply a new approach to the rooting of the eukaryotic tree by using a subset of genomic information with more recent evolutionary origin-mitochondrial sequences, whose closest relatives are α-Proteobacteria. For this, we identified and assembled a data set of 42 mitochondrial proteins (mainly encoded by the nuclear genome) and performed Bayesian and maximum likelihood analyses. Taxon sampling includes the recently sequenced Thecamonas trahens, a member of the phylogenetically elusive Apusozoa. This data set confirms the relationships of several eukaryotic supergroups seen before and places the eukaryotic root between the monophyletic "unikonts" and "bikonts." We further show that T. trahens branches sister to Opisthokonta with significant statistical support and question the bikont/excavate affiliation of Malawimonas species. The mitochondrial data set developed here (to be expanded in the future) constitutes a unique alternative means in resolving deep eukaryotic relationships.
Patients with pulmonary hypertension due to left heart disease (PH-LHD) and a diastolic pulmonary vascular pressure gradient ≥ 7 mm Hg, representing PH out of proportion to pulmonary arterial wedge ...pressure, have pulmonary vascular disease and increased mortality. Little information exists on this condition, recently labeled as "combined pre- and post-capillary PH" (Cpc-PH).
To investigate epidemiology, risk factors, right ventricular function, and outcomes in patients with chronic heart failure and Cpc-PH.
The study population was identified from a retrospective chart review of a clinical database of 3,107 stable patients who underwent first diagnostic right heart catheterization and from a prospective cohort of 800 consecutive patients at a national university-affiliated tertiary center.
The retrospective cohort had 664 patients with systolic heart failure (SHF) and 399 patients with diastolic heart failure (DHF), 12% of whom were classified as Cpc-PH. The prospective cohort had 172 patients with SHF (14% Cpc-PH) and 219 patients with DHF (12% Cpc-PH). Chronic obstructive pulmonary disease (P = 0.034) and the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio (P = 0.015) predicted Cpc-PH in SHF. Younger age (P = 0.004), valvular heart disease (P = 0.046), and the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio predicted Cpc-PH in DHF (P = 0.016). Right ventricular-pulmonary vascular coupling was worse in Cpc-PH patients (end-systolic elastance to effective arterial elastance Ees/Ea: SHF: 1.05 ± 0.25; P = 0.002; DHF: 1.17 ± 0.27; P = 0.027) than in those with isolated post-capillary PH (Ees/Ea: SHF: 1.52 ± 0.51; DHF: 1.45 ± 0.29).
Cpc-PH is rare in chronic heart failure. Right ventricular-pulmonary vascular coupling is poor in Cpc-PH and could be one explanation for dismal outcomes.
DNA-encoded library (DEL) technology is a powerful tool commonly used by the pharmaceutical industry for the identification of compounds with affinity to biomolecular targets. Success in this ...endeavor lies in sampling diverse chemical libraries. However, current DELs tend to be deficient in C(sp3) carbon counts. We report unique solutions to the challenge of increasing both the chemical diversity of these libraries and their C(sp3) carbon counts by merging Ni/photoredox dual catalytic C(sp2)–C(sp3) cross-coupling as well as photoredox-catalyzed radical/polar crossover alkylation protocols with DELs. The successful integration of multiple classes of radical sources enables the rapid incorporation of a diverse set of alkyl fragments.
Although the relationship between psychosocial workplace conditions and musculoskeletal problems has been extensively studied, the causal impact of psychosocial workplace factors in the development ...of musculoskeletal problems remains unclear. The purpose of the present study was to conduct a systematic review of baseline-adjusted prospective longitudinal studies estimating the lagged effect of psychosocial risk factors on musculoskeletal problems in industrialized work settings. A literature review was conducted by searching the MEDLINE, EMBASE, and PsychINFO databases dated until August 2009. The authors classified studies into categories of psychological work stressors and musculoskeletal problems. Available effect sizes were converted to odds ratios (OR). ORs were then pooled for each stressor–problem relationship using a random-effects model. Additionally, the possibility of publication bias was assessed with the Duval and Tweedie nonparametric “trim and fill” procedure. In total, 50 primary studies fulfilled inclusion criteria. Within these studies at least five effect sizes were available for 23 of the 45 possible psychosocial work stress–musculoskeletal problems relationships, leaving 9 psychosocial variables and four musculoskeletal problem areas for analyses. Of these 23 relationships, pooled OR estimates were positive and significant ranging from 1.15 to 1.66 with the largest pooled OR estimating the relationship between highly monotonous work and lower back pain. The lagged effect of low social support on lower limb problems was the only effect size for which the statistical test for bias was significant. Most psychosocial stressors had small but significant lagged effects on the development of musculoskeletal problems. Thus, organizational interventions to minimize these stressors may be promising in reducing one risk factor for the development of employee musculoskeletal problems.
► This is the first meta-analysis on the relationship between psychosocial risk factors at work and musculoskeletal symptoms. ► Psychosocial risk factors at work do in fact have a longitudinal effect on the development of musculoskeletal problems. ► Especially, high monotonous work and lack of social support at work have an influence on the onset of low back pain.
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