235 research outputs found
Observation of a new electronic state of CO perturbing W¹Π1(v=1)
We observe photoabsorption of the W(1) ← X(0) band in five carbon monoxide isotopologues with a vacuum-ultraviolet Fourier-transform spectrometer and a synchrotron radiation source. We deduce transition energies, integrated cross sections, and natural linewidths of the observed rotational transitions and find a perturbation affecting these. Following a deperturbation analysis of all five isotopologues, the perturbing state is assigned to the v = 0 level of a previously unobserved (1)Π state predicted by ab initio calculations to occur with the correct symmetry and equilibrium internuclear distance. We label this new state E″ (1)Π. Both of the interacting levels W(1) and E″(0) are predissociated, leading to dramatic interference effects in their corresponding linewidths.A.H. was supported by
Grant No. 648.000.002 from the Netherlands Organisation
for Scientific Research (NWO) via the Dutch Astrochemistry
Network. This research was supported by funds from National
Aeronautics and Space Administration (NASA) (Grant
Nos. NNX09AC5GG to Wellesley College and NNG 06-
GG70G and NNX10AD80G to the University of Toledo),
CNRS (France), and Programme National Physico-Chimie du
Milieu Interstellaire (PCMI). L.G. and J.L.L. acknowledge
the financial support of the European Community 7th Framework
Programme (FP7/2007-2013) Marie Curie ITN under
Grant Agreement # 238258
High-Resolution Oscillator Strength Measurements of the v\u27 = 0,1 Bands of the B-X, C-X, and E-X Systems in Five Isotopologues of Carbon Monoxide
We report oscillator strengths for six strong vibrational bands between 105.0 and 115.2 nm, associated with transitions from the v = 0 level of the X 1Σ+ ground state to the v = 0 and 1 levels of the B 1Σ+, C 1Σ+, and E 1Π states, in 12C16O, 12C17O, 12C18O, 13C16O, and 13C18O. These measurements extend the development of a comprehensive database of line positions, oscillator strengths, and linewidths of photodissociating transitions for all astrophysically relevant CO isotopologues. The E–X bands, in particular, play central roles in CO photodissociation and fractionationmodels of interstellar clouds and circumstellar disks including the early solar nebula. The resolving powers of the room-temperature measurements, R = 300,000–400,000, allow for the analysis of individual line strengths within bands; the measurements reveal J-dependences in the branch intensities of the C(v = 0,1)–X(0) and E(v = 0,1)–X(0) bands in all isotopologues. Minimal or no isotopologue dependence was found in the f-values of the C(v = 0,1)–X(0) and E(v = 0,1)–X(0) bands at a ∼5% uncertainty level. Revised dissociation branching ratios for the C(v = 0,1) and E(v = 0,1) levels are computed based on these f-values. The weak isotopologue dependence of the f-values presented here eliminates this mechanism as an explanation for the large 17O enrichments seen in recent laboratory photolysis experiments on CO at wavelengths from 105 to 108 nm
Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand.
OBJECTIVE: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. DESIGN: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. METHODS: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. RESULTS: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. CONCLUSION: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age
Relationships between body growth indices and environmental factors on the reproductive cycle of the Gymnodactylus geckoides Spix, 1825 (Squamata, Gymnophthalmidae) in Northeast Brazil
In this study, we analyzed the energy and reproductive cycles of female and male Gymnodactylus geckoides in the Caatinga area of northeast Brazil. We investigated whether these proxies of body condition, such as reproductive cells maturation and cellular structures changed in response to variation in abiotic and biotic factors (i.e., humidity, temperature, seasonality, body temperature, growing rate and gonad volume), using individuals stored under scientific conditions collected between September 2018 and December 2021. The condition factor showed an isometric growth pattern in the population studied. Meanwhile, the lipid, hepatic, and gonad factors correlated with body growth and showed monthly and seasonal variations, as well as reproductive cell maturation and cellular structure morphology. The cycles displayed constant replacement of energy reserves and mature reproductive cells, indicating constant and acyclic reproduction in G. geckoides. Energy reserves appear to be used for many reproductive activities, including meeting, gestation, and egg laying that occur at different frequencies during different periods in the dry and rainy seasons. Therefore, the reproductive cycle is likely to be strongly controlled by biotic factors, which are modeled using abiotic factors and environmental conditions (environmental patterns which proportionate greater resource availability). Our study is the first to investigate energy cycles and reproductive strategies in G. geckoides. It has shown that this species stores greater amounts of energy during the rainy season and then depletes these reserves during the dry period, since the rainy season correspond to the increase in energy consumption, mainly because of gestation and egg laying.Asociación Herpetológica Argentin
Essential role of proteasomes in maintaining self-renewal in neural progenitor cells
Protein turnover and homeostasis are regulated by the proteasomal system, which is critical for cell function and viability. Pluripotency of stem cells also relies on normal proteasomal activity that mitigates senescent phenotypes induced by intensive cell replications, as previously demonstrated in human bone marrow stromal cells. In this study, we investigated the role of proteasomes in self-renewal of neural progenitor cells (NPCs). Through both in vivo and in vitro analyses, we found that the expression of proteasomes was progressively decreased during aging. Likewise, proliferation and self-renewal of NPCs were also impaired in aged mice, suggesting that the down-regulation of proteasomes might be responsible for this senescent phenotype. Lowering proteasomal activity by loss-of-function manipulations mimicked the senescence of NPCs both in vitro and in vivo; conversely, enhancing proteasomal activity restored and improved self-renewal in aged NPCs. These results collectively indicate that proteasomes work as a key regulator in promoting self-renewal of NPCs. This potentially provides a promising therapeutic target for age-dependent neurodegenerative diseases
Extra virgin olive oil consumption reduces the risk of osteoporotic fractures in the PREDIMED trial
BACKGROUND & AIMS:
The incidence of osteoporotic fractures is lower in countries in the Mediterranean basin. Virgin olive oil, a key component of the Mediterranean Diet (MDiet), with recognised beneficial effects on metabolism and cardiovascular health, may decrease the risk of osteoporotic fractures. The aim to this study was to explore the effect of chronic consumption of total olive oil and its varieties on the risk of osteoporosis-related fractures in a middle-aged and elderly Mediterranean population.
METHODS:
We included all participants (n = 870) recruited in the Reus (Spain) centre of the PREvención con DIeta MEDiterránea (PREDIMED) trial. Individuals, aged 55-80 years at high cardiovascular risk, were randomized to a MedDiet supplemented with extra-virgin olive oil, a MedDiet supplemented with nuts, or a low-fat diet. The present analysis was an observational cohort study nested in the trial. A validated food frequency questionnaire was used to assess dietary habits and olive oil consumption. Information on total osteoporotic fractures was obtained from a systematic review of medical records. The association between yearly repeated measurements of olive oil consumption and fracture risk was assessed by multivariate Cox proportional hazards.
RESULTS:
We documented 114 incident cases of osteoporosis-related fractures during a median follow-up of 8.9 years. Treatment allocation had no effect on fracture risk. Participants in the highest tertile of extra-virgin olive oil consumption had a 51% lower risk of fractures (HR:0.49; 95% CI:0.29-0.81. P for trend = 0.004) compared to those in the lowest tertile after adjusting for potential confounders. Total and common olive oil consumption was not associated with fracture risk.
CONCLUSIONS:
Higher consumption of extra-virgin olive oil is associated with a lower risk of osteoporosis-related fractures in middle-aged and elderly Mediterranean population at high cardiovascular risk
Ellenberg-type indicator values for European vascular plant species
Aims: Ellenberg-type indicator values are expert-based rankings of plant species according to their ecological optima on main environmental gradients. Here we extend the indicator-value system proposed by Heinz Ellenberg and co-authors for Central Europe by incorporating other systems of Ellenberg-type indicator values (i.e., those using scales compatible with Ellenberg values) developed for other European regions. Our aim is to create a harmonized data set of Ellenberg-type indicator values applicable at the European scale. Methods: We collected European data sets of indicator values for vascular plants and selected 13 data sets that used the nine-, ten- or twelve-degree scales defined by Ellenberg for light, temperature, moisture, reaction, nutrients and salinity. We compared these values with the original Ellenberg values and used those that showed consistent trends in regression slope and coefficient of determination. We calculated the average value for each combination of species and indicator values from these data sets. Based on species’ co-occurrences in European vegetation plots, we also calculated new values for species that were not assigned an indicator value. Results: We provide a new data set of Ellenberg-type indicator values for 8908 European vascular plant species (8168 for light, 7400 for temperature, 8030 for moisture, 7282 for reaction, 7193 for nutrients, and 7507 for salinity), of which 398 species have been newly assigned to at least one indicator value. Conclusions: The newly introduced indicator values are compatible with the original Ellenberg values. They can be used for large-scale studies of the European flora and vegetation or for gap-filling in regional data sets. The European indicator values and the original and taxonomically harmonized regional data sets of Ellenberg-type indicator values are available in the Supporting Information and the Zenodo repository
Synaptic Proteins Linked to HIV-1 Infection and Immunoproteasome Induction: Proteomic Analysis of Human Synaptosomes
Infection of the central nervous system with human immunodeficiency virus type 1 (HIV-1) can produce morphological changes in the neocortical synaptodendritic arbor that are correlated with neurocognitive impairment. To determine whether HIV-1 infection influences the protein composition of human synapses, a proteomic study of isolated nerve endings was undertaken. Synaptosomes from frontal neocortex were isolated using isopyknic centrifugation from 19 human brain specimens. Purity and enrichment were assessed by measuring pre- and postsynaptic protein markers. Two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry was used to screen for proteins differentially expressed in HIV/AIDS. The concentrations of 31 candidate protein spots were potentially abnormal in HIV-infected decedents with HIV encephalitis and/or increased expression of immunoproteasome subunits. Immunoblots showed that the concentration of some of them was related to HIV-1 infection of the brain and immunoproteasome (IPS) induction. Synapsin 1b and stathmin were inversely related to brain HIV-1 load; 14-3-3ζ and 14-4-4ε proteins were higher in subjects with HIV-1 loads. Perturbed synaptosome proteins were linked with IPS subunit composition, and 14-3-3ζ was histologically colocalized with IPS subunits in stained neocortical neurons. Proteomics illustrates that certain human proteins within the synaptic compartment are involved with changes in the synaptodendritic arbor and neurocognitive impairment in HIV-1-infected people
Wage inequality, segregation by skill and the price of capital in an assignment model
Some pieces of empirical evidence suggest that in the U.S., over the last few decades, (i) wage inequality between-plants has risen much more than wage inequality within-plants and (ii) there has been an increase in the segregation of workers by skill into separate plants. This paper presents a frictionless assignment model in which these two features can be explained simultaneously as the result of the decline in the relative price of capital. Additional implications of the model regarding the skill premium and the dispersion in labor productivity across plants are also consistent with the empirical evidence. [resumen de autor
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