28 research outputs found
Distribution of star-forming complexes in dwarf irregular galaxies
We study the distribution of bright star-forming complexes in a homogeneous
sample of 72 late-type (``irregular'') dwarf galaxies located within the 10 Mpc
volume. Star-forming complexes are identified as bright lumps in B-band galaxy
images and isolated by means of the unsharp-masking method. For the sample as a
whole the radial number distribution of bright lumps largely traces the
underlying exponential-disk light profiles, but peaks at a 10 percent smaller
scale length. Moreover, the presence of a tail of star forming regions out to
at least six optical scale lengths provides evidence against a systematic star
formation truncation within that galaxy extension. Considering these findings,
we apply a scale length-independent concentration index, taking into account
the implied non-uniform random spread of star formation regions throughout the
disk. The number profiles frequently manifest a second, minor peak at about two
scale lengths. Relying on a two-dimensional stochastic self-propagating star
formation model, we show these secondary peaks to be consistent with triggered
star formation; for a few of the brighter galaxies a peculiar peak distribution
is observed that is conceivably due to the onset of shear provided by
differential rotation. On scales between 100 and 1000 pc, and by taking into
account exponential-disk structure, bright lumps reveal cluster dimensions
between 1.3 and 2, with a weak trend to higher dimensions for brighter
galaxies. Interpreting cluster dimension in terms of porosity of a self-similar
intragalactic medium, we derive a relation between current star formation rate,
scale length, and porosity.Comment: 16 pages, accepted for publication in Astronomy & Astrophysic
Your Unconscious Knows Your Name
One's own name constitutes a unique part of conscious awareness â but does this also hold true for unconscious processing? The present study shows that the own name has the power to bias a person's actions unconsciously even in conditions that render any other name ineffective. Participants judged whether a letter string on the screen was a name or a non-word while this target stimulus was preceded by a masked prime stimulus. Crucially, the participant's own name was among these prime stimuli and facilitated reactions to following name targets whereas the name of another, yoked participant did not. Signal detection results confirmed that participants were not aware of any of the prime stimuli, including their own name. These results extend traditional findings on âbreakthroughâ phenomena of personally relevant stimuli to the domain of unconscious processing. Thus, the brain seems to possess adroit mechanisms to identify and process such stimuli even in the absence of conscious awareness
Protocol for a randomized controlled study of Iyengar yoga for youth with irritable bowel syndrome
<p>Abstract</p> <p>Introduction</p> <p>Irritable bowel syndrome affects as many as 14% of high school-aged students. Symptoms include discomfort in the abdomen, along with diarrhea and/or constipation and other gastroenterological symptoms that can significantly impact quality of life and daily functioning. Emotional stress appears to exacerbate irritable bowel syndrome symptoms suggesting that mind-body interventions reducing arousal may prove beneficial. For many sufferers, symptoms can be traced to childhood and adolescence, making the early manifestation of irritable bowel syndrome important to understand. The current study will focus on young people aged 14-26 years with irritable bowel syndrome. The study will test the potential benefits of Iyengar yoga on clinical symptoms, psychospiritual functioning and visceral sensitivity. Yoga is thought to bring physical, psychological and spiritual benefits to practitioners and has been associated with reduced stress and pain. Through its focus on restoration and use of props, Iyengar yoga is especially designed to decrease arousal and promote psychospiritual resources in physically compromised individuals. An extensive and standardized teacher-training program support Iyengar yoga's reliability and safety. It is hypothesized that yoga will be feasible with less than 20% attrition; and the yoga group will demonstrate significantly improved outcomes compared to controls, with physiological and psychospiritual mechanisms contributing to improvements.</p> <p>Methods/Design</p> <p>Sixty irritable bowel syndrome patients aged 14-26 will be randomly assigned to a standardized 6-week twice weekly Iyengar yoga group-based program or a wait-list usual care control group. The groups will be compared on the primary clinical outcomes of irritable bowel syndrome symptoms, quality of life and global improvement at post-treatment and 2-month follow-up. Secondary outcomes will include visceral pain sensitivity assessed with a standardized laboratory task (water load task), functional disability and psychospiritual variables including catastrophizing, self-efficacy, mood, acceptance and mindfulness. Mechanisms of action involved in the proposed beneficial effects of yoga upon clinical outcomes will be explored, and include the mediating effects of visceral sensitivity, increased psychospiritual resources, regulated autonomic nervous system responses and regulated hormonal stress response assessed via salivary cortisol.</p> <p>Trial registration</p> <p>ClinicalTrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT01107977">NCT01107977</a>.</p
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Impact of population aging on future temperature-related mortality at different global warming levels
Data availability:
All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Data were collected within the MCC Collaborative Research Network under a data sharing agreement and cannot be made publicly available.Code availability:
A sample of the analysis code is available from https://github.com/CHENlab-Yale/MCC_ProjAging_Temp .Supplementary information is available online at: https://link-springer-com.ezproxytest.brunel.ac.uk/article/10.1038/s41467-024-45901-z#Sec15 .Older adults are generally amongst the most vulnerable to heat and cold. While temperature-related health impacts are projected to increase with global warming, the influence of population aging on these trends remains unclear. Here we show that at 1.5â°C, 2â°C, and 3â°C of global warming, heat-related mortality in 800 locations across 50 countries/areas will increase by 0.5%, 1.0%, and 2.5%, respectively; among which 1 in 5 to 1 in 4 heat-related deaths can be attributed to population aging. Despite a projected decrease in cold-related mortality due to progressive warming alone, population aging will mostly counteract this trend, leading to a net increase in cold-related mortality by 0.1%â0.4% at 1.5â3â°C global warming. Our findings indicate that population aging constitutes a crucial driver for future heat- and cold-related deaths, with increasing mortality burden for both heat and cold due to the aging population.We acknowledge the World Climate Research Programme, which, through its Working Group on Coupled Modeling, coordinated and promoted CMIP6. We thank the climate modeling groups for producing and making available their model output, the Earth System Grid Federation (ESGF) for archiving the data and providing access, and the multiple funding agencies who support CMIP6 and ESGF. K.C. was supported by the Yale Planetary Solutions Project seed grant. A.G., A.S., and S.R. were supported by the European Unionâs Horizon 2020 Project Exhaustion grant (820655). A.G. was also supported by the Medical Research Council UK grant (MR/V034162/1). J.M. received funding from the Fundação para a CiĂŞncia e a Tecnlogia Grant (SFRH/BPD/115112/2016). A.T. was supported by the MCIN/AEI/10.13039/501100011033 grant (CEX2018-000794-S). A.U. and J.K. were supported by the Czech Science Foundation (22-24920S). F.S. was supported by the Italian Ministry of University and Research (MUR), Department of Excellence project 2023-2027 ReDS âRethinking Data Scienceâ - Department of Statistics, Computer Science and Applications - University of Florence. MNM. was supported by the European Commission (H2020-MSCA-IF-2020) under REA grant agreement no. 101022870. A.V.C. acknowledges the support of the Swiss National Foundation (TMSGI3_211626). V.H. received funding from the European Unionâs Horizon 2020 research and innovation program (Marie SkĹodowska-Curie Grant Agreement No.: 101032087)
Directed Evolution Mimics Allosteric Activation by Stepwise Tuning of the Conformational Ensemble
Allosteric enzymes contain a wealth
of catalytic diversity that
remains distinctly underutilized for biocatalysis. Tryptophan synthase
is a model allosteric system and a valuable enzyme for the synthesis
of noncanonical amino acids (ncAA). Previously, we evolved the β-subunit
from <i>Pyrococcus furiosus</i>, <i>Pf</i>TrpB,
for ncAA synthase activity in the absence of its native partner protein <i>Pf</i>TrpA. However, the precise mechanism by which mutation
activated TrpB to afford a stand-alone catalyst remained enigmatic.
Here, we show that directed evolution caused a gradual change in the
rate-limiting step of the catalytic cycle. Concomitantly, the steady-state
distribution of the intermediates shifts to favor covalently bound
Trp adducts, which have increased thermodynamic stability. The biochemical
properties of these evolved, stand-alone TrpBs converge on those induced
in the native system by allosteric activation. High-resolution crystal
structures of the wild-type enzyme, an intermediate in the lineage,
and the final variant, encompassing five distinct chemical states,
show that activating mutations have only minor structural effects
on their immediate environment. Instead, mutation stabilizes the large-scale
motion of a subdomain to favor an otherwise transiently populated
closed conformational state. This increase in stability enabled the
first structural description of Trp covalently bound in a catalytically
active TrpB, confirming key features of catalysis. These data combine
to show that sophisticated models of allostery are not a prerequisite
to recapitulating its complex effects via directed evolution, opening
the way to engineering stand-alone versions of diverse allosteric
enzymes