First-row transition-metal-mediated reactions constitute an important and growing area of research due to the low cost, low toxicity, and exceptional synthetic versatility of these metals. Currently, ...there is considerable effort to replace existing precious-metal-catalyzed reactions with first-row analogs. More importantly, there are a plethora of unique transformations mediated by first-row metals, which have no classical second- or third-row counterpart. Herein, the application of first-row metal-mediated methods to the total synthesis of natural products is discussed. This Review is intended to highlight strategic uses of these metals to realize efficient syntheses and highlight the future potential of these reagents and catalysts in organic synthesis.
The COVID-19 lockdown interrupted normal daily activities, which may have led to an increase in sedentary behavior (Castelnuovo et al., 2020). The aim of this study was to investigate the effect of ...the COVID-19 pandemic on the level of physical activity among Swiss office workers.
Office workers from two Swiss organizations, aged 18-65 years, were included. Baseline data from January 2020 before the COVID-19 pandemic became effective in Switzerland were compared with follow-up data during the lockdown phase in April 2020. Levels of physical activity were assessed using the International Physical Activity Questionnaire. Paired sample
-tests or Wilcoxon signed-rank test were performed for statistical analysis.
Data from 76 participants were analyzed. Fifty-four participants were female (71.1%). The mean age was 42.7 years (range from 21.8 to 62.7) at baseline. About 75% of the participants met the recommendations on minimal physical activity, both before the COVID-19 pandemic and during the lockdown. Weak statistical evidence for a decline in total physical activity in metabolic equivalent of task minutes per week (MET min/week) was found (estimate = -292, 95% CI from - ∞ to 74,
-value = 0.09), with no evidence for a decrease in the three types of activity: walking (estimate = -189, 95% CI from - ∞ to 100,
-value = 0.28), moderate-intensity activity (estimate = -200, 95% CI from - ∞ to 30,
-value = 0.22) and vigorous-intensity activity (estimate = 80, 95% CI from - ∞ to 460,
-value = 0.74). Across the three categories "high," "moderate," and "low" physical activity, 17% of the participants became less active during the lockdown while 29% became more active.
The COVID-19 pandemic did not result in a reduction in total physical activity levels among a sample of Swiss office workers during the first weeks of lockdown. Improved work-life balance and working times may have contributed to this finding.
www.ClinicalTrials.gov, NCT04169646. Registered 15 November 2019 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04169646.
Searches for dark matter with liquid xenon time projection chamber experiments have traditionally focused on the region of the parameter space that is characteristic of weakly interacting massive ...particles, ranging from a few GeV/c2 to a few TeV/c2. Models of dark matter with a mass much heavier than this are well motivated by early production mechanisms different from the standard thermal freeze-out, but they have generally been less explored experimentally. In this work, we present a reanalysis of the first science run of the LZ experiment, with an exposure of 0.9 tonne x yr, to search for ultraheavy particle dark matter. The signal topology consists of multiple energy deposits in the active region of the detector forming a straight line, from which the velocity of the incoming particle can be reconstructed on an event-by-event basis. Zero events with this topology were observed after applying the data selection calibrated on a simulated sample of signal-like events. New experimental constraints are derived, which rule out previously unexplored regions of the dark matter parameter space of spin-independent interactions beyond a mass of 1017 GeV/c2.
A new class of bidirectionally quantitative photoswitches based on the hemithioindigo (HTI) scaffold is reported. Incorporation of a pyrrole hydrogen-bond donor leads to a bathochromic shift allowing ...for quantitative bidirectional isomerization. Additionally, extending conjugation from the electron-rich pyrrole results in quantitative visible-light photoswitches, as well as photoswitches that isomerize with red and near-infrared light. The presence of the hydrogen bond leading to the observed redshift is supported by computational and spectroscopic evidence.
We report the total syntheses of two indole diterpenoid natural products, paspaline A and emindole PB. Paspaline A is synthesized in a 9-step sequence from commercially available materials. The first ...total synthesis of emindole PB is accomplished in 13 steps and confirms a previously ambiguous structural assignment. Density functional theory calculations are utilized to interrogate the key carbocationic rearrangement in a predictive capacity to aid in the selection of the most favorable precursor substrate. This work highlights how retrosynthetic design can be augmented with quantum chemical calculations to reveal energetically feasible synthetic disconnections, minimizing time-consuming and expensive empirical evaluation.
Knowledge hiding in organizations Connelly, Catherine E.; Zweig, David; Webster, Jane ...
Journal of organizational behavior,
January 2012, Letnik:
33, Številka:
1
Journal Article
Recenzirano
Despite the efforts to enhance knowledge transfer in organizations, success has been elusive. It is becoming clear that in many instances employees are unwilling to share their knowledge even when ...organizational practices are designed to facilitate transfer. Consequently, this paper develops and investigates a novel construct, knowledge hiding. We establish that knowledge hiding exists, we distinguish knowledge hiding from related concepts (knowledge hoarding and knowledge sharing), and we develop a multidimensional measure of this construct. We also identify several predictors of knowledge hiding in organizations. The results of three studies, using different methods, suggest that knowledge hiding is comprised of three related factors: evasive hiding, rationalized hiding, and playing dumb. Each of these hiding behaviors is predicted by distrust, yet each also has a different set of interpersonal and organizational predictors. We draw implications for future research on knowledge management.
Activation of the antioxidant regulatory transcription factor NRF2 (Nuclear factor erythroid-derived 2) regulates cellular bioenergetics and improves neuronal health in aging. Yet how NRF2 ...participates in maintaining synaptic, mitochondrial and cognitive function has not been fully elucidated. This study investigates how loss of NRF2 affects neuronal metabolism, synaptic density and cognitive performance in aged mice.
Dendritic arborization as well as synaptic and mitochondrial gene expression was evaluated in hippocampal neurons isolated from mice lacking NRF2 (NRF2KO) and from wild-type (WT) C57BL6 mice. Mitochondrial function of these neurons was evaluated using the Seahorse XF platform. Additionally learning, memory and executive function were assessed in 20 month old NRF2KO and age-matched WT mice using conditioned fear response (CFR) and odor discrimination reversal learning (ODRL) tests. Hippocampal bioenergetics was profiled using mitochondria isolated from these animals and tissue was harvested for assessment of mitochondrial and synaptic genes.
NRF2KO neurons had reduced dendritic complexity and diminished synaptic gene expression. This was accompanied by impaired mitochondrial function and decreased mitochondrial gene expression. Similar mitochondrial deficits were observed in the brains of aged NRF2KO mice. These animals also had significantly impaired cognitive performance and reduced synaptic gene expression as well.
These data point to a role for NRF2 in maintaining mitochondrial and cognitive function during aging and suggest that the transcription factor may be a viable target for cognitive enhancing interventions. Because mitochondrial dysfunction and cognitive impairment also occur together in many neurodegenerative conditions there may be broad therapeutic potential of NRF2 activating agents.
•Neurons lacking NRF2 have reduced synaptic density and dendritic arborization.•Neurons lacking NRF2 have increased oxidative stress and mitochondrial dysfunction.•Aged NRF2KO mice display deficits in learning, memory and executive function.•No differences in cognitive function are observed in young NRF2KO mice.
Research has begun to document the negative organizational consequences of knowledge hiding, or the intentional attempt to conceal knowledge, among employees. However, different knowledge hiding ...behaviours exist, and we explore whether some types of knowledge hiding are more harmful than others. Although theory would suggest that knowledge hiders rationalize their behaviours and fail to anticipate the negative consequences of their behaviours, we found that they did anticipate harmed relationships and retaliation. In addition, targets of knowledge hiding did not always construe the behaviour as harmful or as necessitating retaliation. Overall, our research suggests that not all knowledge hiding is equally harmful. Some types of knowledge hiding may actually enhance the relationships between colleagues and might break the cycle of knowledge hiding in organizations.
The University of California, Santa Cruz Genome Browser (http://genome.ucsc.edu) offers online access to a database of genomic sequence and annotation data for a wide variety of organisms. The ...Browser also has many tools for visualizing, comparing and analyzing both publicly available and user-generated genomic data sets, aligning sequences and uploading user data. Among the features released this year are a gene search tool and annotation track drag-reorder functionality as well as support for BAM and BigWig/BigBed file formats. New display enhancements include overlay of multiple wiggle tracks through use of transparent coloring, options for displaying transformed wiggle data, a 'mean+whiskers' windowing function for display of wiggle data at high zoom levels, and more color schemes for microarray data. New data highlights include seven new genome assemblies, a Neandertal genome data portal, phenotype and disease association data, a human RNA editing track, and a zebrafish Conservation track. We also describe updates to existing tracks.
The University of California, Santa Cruz (UCSC) Genome Browser website (http://genome.ucsc.edu/) provides a large database of publicly available sequence and annotation data along with an integrated ...tool set for examining and comparing the genomes of organisms, aligning sequence to genomes, and displaying and sharing users' own annotation data. As of September 2009, genomic sequence and a basic set of annotation 'tracks' are provided for 47 organisms, including 14 mammals, 10 non-mammal vertebrates, 3 invertebrate deuterostomes, 13 insects, 6 worms and a yeast. New data highlights this year include an updated human genome browser, a 44-species multiple sequence alignment track, improved variation and phenotype tracks and 16 new genome-wide ENCODE tracks. New features include drag-and-zoom navigation, a Wiki track for user-added annotations, new custom track formats for large datasets (bigBed and bigWig), a new multiple alignment output tool, links to variation and protein structure tools, in silico PCR utility enhancements, and improved track configuration tools.
PDF
