341 research outputs found
Multiple Continental Radiations and Correlates of Diversification in Lupinus (Leguminosae): Testing for Key Innovation with Incomplete Taxon Sampling
Replicate radiations provide powerful comparative systems to address questions about the interplay between opportunity and innovation in driving episodes of diversification and the factors limiting their subsequent progression. However, such systems have been rarely documented at intercontinental scales. Here, we evaluate the hypothesis of multiple radiations in the genus Lupinus (Leguminosae), which exhibits some of the highest known rates of net diversification in plants. Given that incomplete taxon sampling, background extinction, and lineage-specific variation in diversification rates can confound macroevolutionary inferences regarding the timing and mechanisms of cladogenesis, we used Bayesian relaxed clock phylogenetic analyses as well as MEDUSA and BiSSE birth-death likelihood models of diversification, to evaluate the evolutionary patterns of lineage accumulation in Lupinus. We identified 3 significant shifts to increased rates of net diversification (r) relative to background levels in the genus (r = 0.18-0.48 lineages/myr). The primary shift occurred approximately 4.6 Ma (r = 0.48-1.76) in the montane regions of western North America, followed by a secondary shift approximately 2.7 Ma (r = 0.89-3.33) associated with range expansion and diversification of allopatrically distributed sister clades in the Mexican highlands and Andes. We also recovered evidence for a third independent shift approximately 6.5 Ma at the base of a lower elevation eastern South American grassland and campo rupestre clade (r = 0.36-1.33). Bayesian ancestral state reconstructions and BiSSE likelihood analyses of correlated diversification indicated that increased rates of speciation are strongly associated with the derived evolution of perennial life history and invasion of montane ecosystems. Although we currently lack hard evidence for "replicate adaptive radiationsā in the sense of convergent morphological and ecological trajectories among species in different clades, these results are consistent with the hypothesis that iteroparity functioned as an adaptive key innovation, providing a mechanism for range expansion and rapid divergence in upper elevation regions across much of the New Worl
Regulation of Star Formation by a Hot Circumgalactic Medium
Galactic outflows driven by supernovae (SNe) are thought to be a powerful
regulator of a galaxy's star-forming efficiency. Mass, energy, and metal
outflows (, , and , here normalized by the star
formation rate, the SNe energy and metal production rates, respectively) shape
galaxy properties by both ejecting gas and metals out of the galaxy and by
heating the circumgalactic medium (CGM), preventing future accretion.
Traditionally, models have assumed that galaxies self-regulate by ejecting a
large fraction of the gas which enters the interstellar medium (ISM), even
though such high mass-loadings are in growing tension with observations. To
better understand how the relative importance of ejective (i.e. high
mass-loading) vs preventative (i.e. high energy-loading) feedback affects the
present-day properties of galaxies, we develop a simple gas-regulator model of
galaxy evolution, where the stellar mass, ISM, and CGM are modeled as distinct
reservoirs which exchange mass, metals, and energy at different rates within a
growing halo. Focusing on the halo mass range from to , we demonstrate that, with reasonable parameter choices, we can
reproduce the stellar-to-halo mass relation and the ISM-to-stellar mass
relation with low mass-loaded () but high energy-loaded
() winds, with self-regulation occurring primarily through
heating and cooling of the CGM. We show that the model predictions are robust
against changes to the mass-loading of outflows but are quite sensitive to our
choice of the energy-loading, preferring for the lowest mass
halos and for Milky Way-like halos.Comment: 19 pages, 9 Figures, submitted to Ap
Impact of Cosmic Rays on Thermal Instability in the Circumgalactic Medium
Large reservoirs of cold (~10ā“ K) gas exist out to and beyond the virial radius in the circumgalactic medium (CGM) of all types of galaxies. Photoionization modeling suggests that cold CGM gas has significantly lower densities than expected by theoretical predictions based on thermal pressure equilibrium with hot CGM gas. In this work, we investigate the impact of cosmic-ray physics on the formation of cold gas via thermal instability. We use idealized three-dimensional magnetohydrodynamic simulations to follow the evolution of thermally unstable gas in a gravitationally stratified medium. We find that cosmic-ray pressure lowers the density and increases the size of cold gas clouds formed through thermal instability. We develop a simple model for how the cold cloud sizes and the relative densities of cold and hot gas depend on cosmic-ray pressure. Cosmic-ray pressure can help counteract gravity to keep cold gas in the CGM for longer, thereby increasing the predicted cold mass fraction and decreasing the predicted cold gas inflow rates. Efficient cosmic-ray transport, by streaming or diffusion, redistributes cosmic-ray pressure from the cold gas to the background medium, resulting in cold gas properties that are in between those predicted by simulations with inefficient transport and simulations without cosmic rays. We show that cosmic rays can significantly reduce galactic accretion rates and resolve the tension between theoretical models and observational constraints on the properties of cold CGM gas
Anakinra reduces blood pressure and renal fibrosis in one kidney/DOCA/salt-induced hypertension
OBJECTIVE: To determine whether a clinically-utilised IL-1 receptor antagonist, anakinra, reduces renal inflammation, structural damage and blood pressure (BP) in mice with established hypertension. METHODS: Hypertension was induced in male mice by uninephrectomy, deoxycorticosterone acetate (2.4mg/d,s.c.) and replacement of drinking water with saline (1K/DOCA/salt). Control mice received uninephrectomy, a placebo pellet and normal drinking water. 10days post-surgery, mice commenced treatment with anakinra (75mg/kg/d, i.p.) or vehicle (0.9% saline, i.p.) for 11 days. Systolic BP was measured by tail cuff while qPCR, immunohistochemistry and flow cytometry were used to measure inflammatory markers, collagen and immune cell infiltration in the kidneys. RESULTS: By 10 days post-surgery, 1K/DOCA/salt-treated mice displayed elevated systolic BP (148.3+/-2.4mmHg) compared to control mice (121.7+/-2.7mmHg; n=18, P\u3c0.0001). The intervention with anakinra reduced BP in 1K/DOCA/salt-treated mice by approximately 20mmHg (n=16, P\u3c0.05), but had no effect in controls. In 1K/DOCA/salt-treated mice, anakinra modestly reduced ( approximately 30%) renal expression of some (CCL5, CCL2; n=7-8; P\u3c0.05) but not all (ICAM-1, IL-6) inflammatory markers, and had no effect on immune cell infiltration (n=7-8, P \u3e 0.05). Anakinra reduced renal collagen content (n=6, P\u3c0.01) but paradoxically appeared to exacerbate the renal and glomerular hypertrophy (n=8-9, P\u3c0.001) that accompanied 1K/DOCA/salt-induced hypertension. CONCLUSION: Despite its anti-hypertensive and renal anti-fibrotic actions, anakinra had minimal effects on inflammation and leukocyte infiltration in mice with 1K/DOCA/salt-induced hypertension. Future studies will assess whether the anti-hypertensive actions of anakinra are mediated by protective actions in other BP-regulating or salt-handling organs such as the arteries, skin and brain
Differential effects of sertraline and cognitive behavioural therapy on behavioural inhibition in patients with obsessive compulsive disorder
Ā© 2024 The Author(s). Published by Wolters Kluwer Health, Inc. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Patients with obsessive compulsive disorder (OCD) randomised to sertraline, manualised cognitive behavioural therapy (CBT), or combination (sertralineā
+ā
CBT), underwent cognitive assessment. Cognitive testing was conducted at baseline and at week 16. The stop signal reaction time task (SSRT) was used to evaluate motor impulsivity and attentional flexibility was evaluated using the intra/extra-dimensional set shifting task. Paired-samples t-tests or nonparametric variants were used to compare baseline and posttreatment scores within each treatment group. Forty-five patients were tested at baseline (sertraline nā
=ā
14; CBT nā
=ā
14; sertralineā
+ā
CBT nā
=ā
17) and 23 patients at week 16 (sertraline nā
=ā
6; CBT nā
=ā
7; sertralineā
+ā
CBT nā
=ā
10). The mean dosage of sertraline was numerically higher in those taking sertraline as a monotherapy (166.67ā
mg) compared with those taking sertraline in combination with CBT (100ā
mg). Analysis of pre-post treatment scores using an intent-to-treat-analysis found a significant reduction in the SSRT in those treated with sertraline, whilst there was no significant change on this task for those treated with CBT or the combination. This study found that motor inhibition improved significantly following sertraline monotherapy. Suboptimal sertraline dosing might explain the failure to detect an effect on motor inhibition in the group receiving combination of sertralineā
+ā
CBT. Higher dose sertraline may have broader cognitive effects than CBT for OCD, motor impulsivity may have value as a measure of treatment outcome and, by extension, the SSRT could serve as a biomarker for personalising care.Peer reviewe
Land Cover Trends Dataset, 1973ā2000
The U.S. Geological Survey Land Cover Trends Project is releasing a 1973ā2000 time-series land-use/land-cover dataset for the conterminous United States. The dataset contains 5 dates of land-use/land-cover data for 2,688 sample blocks randomly selected within 84 ecological regions. The nominal dates of the land-use/land-cover maps are 1973, 1980, 1986, 1992, and 2000. The land-use/land-cover maps were classified manually from Landsat Multispectral Scanner, Thematic Mapper, and Enhanced Thematic Mapper Plus imagery using a modified Anderson Level I classification scheme. The resulting land-use/land-cover data has a 60-meter resolution and the projection is set to Albers Equal-Area Conic, North American Datum of 1983. The files are labeled using a standard file naming convention that contains the number of the ecoregion, sample block, and Landsat year. The downloadable files are organized by ecoregion, and are available in the ERDAS IMAGINETM (.img) raster file format
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