Increased efficiency of energy harvest, due to alterations in the gut microbiota (increased Firmicutes and decreased Bacteroidetes), has been implicated in obesity in mice and humans. However, a ...causal relationship is unproven and contributory variables include diet, genetics and age. Therefore, we explored the effect of a high-fat (HF) diet and genetically determined obesity (ob/ob) for changes in microbiota and energy harvesting capacity over time.
Seven-week-old male ob/ob mice were fed a low-fat diet and wild-type mice were fed either a low-fat diet or a HF-diet for 8 weeks (n=8/group). They were assessed at 7, 11 and 15 weeks of age for: fat and lean body mass (by NMR); faecal and caecal short-chain fatty acids (SCFA, by gas chromatography); faecal energy content (by bomb calorimetry) and microbial composition (by metagenomic pyrosequencing).
A progressive increase in Firmicutes was confirmed in both HF-fed and ob/ob mice reaching statistical significance in the former, but this phylum was unchanged over time in the lean controls. Reductions in Bacteroidetes were also found in ob/ob mice. However, changes in the microbiota were dissociated from markers of energy harvest. Thus, although the faecal energy in the ob/ob mice was significantly decreased at 7 weeks, and caecal SCFA increased, these did not persist and faecal acetate diminished over time in both ob/ob and HF-fed mice, but not in lean controls. Furthermore, the proportion of the major phyla did not correlate with energy harvest markers.
The relationship between the microbial composition and energy harvesting capacity is more complex than previously considered. While compositional changes in the faecal microbiota were confirmed, this was primarily a feature of high-fat feeding rather than genetically induced obesity. In addition, changes in the proportions of the major phyla were unrelated to markers of energy harvest which changed over time. The possibility of microbial adaptation to diet and time should be considered in future studies.
ABSTRACT
We study the rest-frame ultraviolet (UV) continuum slopes (β) of galaxies at redshifts 8 < z < 16 (〈z〉 = 10), using a combination of JWST ERO and ERS NIRCam imaging and ground-based ...near-infrared imaging of the COSMOS field. The combination of JWST and ground-based imaging provides a wide baseline in both redshift and absolute UV magnitude (−22.6 < MUV < −17.9), sufficient to allow a meaningful comparison to previous results at lower redshift. Using a power-law fitting technique, we find that our full sample (median MUV = −19.3 ± 1.3) returns an inverse-variance weighted mean value of 〈β〉 = −2.10 ± 0.05, with a corresponding median value of β = −2.29 ± 0.09. These values imply that the UV colours of galaxies at z > 8 are, on average, no bluer than the bluest galaxies in the local universe (e.g. NGC 1705; β = −2.46). We find evidence for a β − MUV relation, such that brighter UV galaxies display redder UV slopes ($\rm {d}\beta / \rm {d} M_{\rm UV} = -0.17 \pm 0.05$). Comparing to results at lower redshift, we find that the slope of our β − MUV relation is consistent with the slope observed at z ≃ 5 and that, at a given MUV, our 8 < z < 16 galaxies are bluer than their z ≃ 5 counterparts, with an inverse-variance weighted mean offset of 〈Δβ〉 = −0.38 ± 0.09. We do not find strong evidence that any objects in our sample display ultra-blue UV continuum slopes (i.e. β ≲ −3) that would require their UV emission to be dominated by ultra-young, dust-free stellar populations with high Lyman-continuum escape fractions. Comparing our results to the predictions of theoretical galaxy formation models, we find that the galaxies in our sample are consistent with the young, metal-poor, and moderately dust-reddened galaxies expected at z > 8.
Background
NYX-2925 is a novel
N
-methyl-
d
-aspartate receptor (NMDAR) modulator that has been shown to facilitate both NMDAR-dependent long-term potentiation (LTP) in vitro and learning and memory ...in vivo.
Objective
The present studies examine the effects of NYX-2925 on NMDAR-dependent auditory LTP (aLTP) in vivo.
Methods
NMDAR-dependent aLTP and NMDAR-dependent auditory mismatch negativity (MMN) was measured, as well as changes in resting-state qEEG power.
Results
NYX-2925 (1, 10 mg/kg PO) increased aLTP 1 h after auditory tetanus measured by the post- minus pre-tetanus difference waveform 140–180 ms post tone onset. NYX-2925 (0.1, 1 mg/kg PO) facilitated MMN measured by the difference waveform (i.e., deviant minus standard tones). NYX-2925 (0.1, 1, 10 mg/kg PO) also enhanced resting-state alpha qEEG power. Conversely, the NMDAR glutamate site antagonist CPP (10 mg/kg IP) reduces alpha power and MMN and produces an opposite effect as NYX-2925 on aLTP.
Conclusions
Together, these data suggest that the activation of the NMDAR by NYX-2925 enhances synaptic plasticity in vivo
,
which may both reduce symptoms of neurological disorders and serve as a biomarker for drug effects. This is the first demonstration of a long-lasting (1-h post-tetanus) effect of NMDAR modulation on synaptic plasticity processes in vivo using a noninvasive technique in freely behaving animals.
Diagnostic errors in radiology are classified as perception or interpretation errors. This study determined whether specific conditions differed when perception or interpretation errors occurred ...during neuroradiology image interpretation.
In a sample of 254 clinical error cases in diagnostic neuroradiology, we classified errors as perception or interpretation errors, then characterized imaging technique, interpreting radiologist's experience, anatomic location of the abnormality, disease etiology, time of day, and day of the week. Interpretation and perception errors were compared with hours worked per shift, cases read per shift, average cases read per shift hour, and the order of case during the shift when the error occurred.
Perception and interpretation errors were 74.8% (
= 190) and 25.2% (
= 64) of errors, respectively. Logistic regression analyses showed that the odds of an interpretation error were 2 times greater (OR, 2.09; 95% CI, 1.05-4.15;
= .04) for neuroradiology attending physicians with ≤5 years of experience. Interpretation errors were more likely with MR imaging compared with CT (OR, 2.10; 95% CI, 1.09-4.01;
= .03). Infectious/inflammatory/autoimmune diseases were more frequently associated with interpretation errors (
= .04). Perception errors were associated with faster reading rates (6.01 versus 5.03 cases read per hour;
= .004) and occurred later during the shift (24th-versus-18th case;
= .04).
Among diagnostic neuroradiology error cases, interpretation-versus-perception errors are affected by the neuroradiologist's experience, technique, and the volume and rate of cases read. Recognition of these risk factors may help guide programs for error reduction in clinical neuroradiology services.
ABSTRACT
We present a new determination of the evolving galaxy ultraviolet (UV) luminosity function (LF) over the redshift range 9.5 < z < 12.5 based on a wide-area (>250 arcmin2) data set of JWST ...NIRCam near-infrared imaging assembled from 13 public JWST surveys. Our relatively large-area search allows us to uncover a sample of 61 robust z > 9.5 candidates detected at ≥8σ, and hence place new constraints on the intermediate-to-bright end of the UV LF. When combined with our previous JWST + UltraVISTA results, this allows us to measure the form of the LF over a luminosity range corresponding to four magnitudes (M1500). At these early times we find that the galaxy UV LF is best described by a double power-law function, consistent with results obtained from recent ground-based and early JWST studies at similar redshifts. Our measurements provide further evidence for a relative lack of evolution at the bright-end of the UV LF at z = 9–11, but do favour a steep faint-end slope (α ≤ −2). The luminosity-weighted integral of our evolving UV LF provides further evidence for a gradual smooth (exponential) decline in co-moving star-formation rate density (ρSFR) at least out to z ≃ 12, with our determination of ρSFR(z = 11) lying significantly above the predictions of many theoretical models of galaxy evolution.
In active volcanic arcs such as the Andean volcanic mountain belt, magmatically sourced fluids are channeled through the brittle crust by faults and fracture networks. In the Andes, volcanoes, ...geothermal springs, and major mineral deposits have a spatial and genetic relationship with NNE trending, margin‐parallel faults and margin‐oblique, NW trending Andean Transverse Faults (ATF). The Tinguiririca and Planchón‐Peteroa volcanoes in the Andean Southern Volcanic Zone (SVZ) demonstrate this relationship, as their spatially associated thermal springs show strike alignment to the NNE oriented El Fierro Thrust Fault System. We constrain the fault system architecture and its interaction with volcanically sourced hydrothermal fluids using a combined magnetotelluric (MT) and seismic survey that was deployed for 20 months. High‐conductivity zones are located along the axis of the active volcanic chain, delineating fluids and/or melt. A distinct WNW trending cluster of seismicity correlates with resistivity contrasts, considered to be a reactivated ATF. Seismicity occurs below 4 km, suggesting activity is limited to basement rocks, and the cessation of seismicity at 9 km delineates the local brittle‐ductile transition. As seismicity is not seen west of the El Fierro fault, we hypothesize that this structure plays a key role in compartmentalizing magmatically derived hydrothermal fluids to the east, where the fault zone acts as a barrier to cross‐fault fluid migration and channels fault‐parallel fluid flow to the surface from depth. Increases in fluid pressure above hydrostatic may facilitate reactivation. This site‐specific case study provides the first three‐dimensional seismic and MT observations of the mechanics behind the reactivation of an ATF.
Key Points
In the Andean volcanic arc, margin‐parallel and blind oblique fault systems control volcanic, hydrothermal, and ore‐porphyry processes
Subsurface conductivity structure and seismicity show a WNW trending active fault in the Andean Southern Volcanic Zone
Results show magmatic/hydrothermal fluids are compartmentalized by local faults and elevated fluid pressures promote fault reactivation
ABSTRACT
We present a study of the connection between the escape fraction of Lyman-alpha ($\mathrm{Ly\, \alpha }$) and Lyman-continuum (LyC) photons within a sample of N = 152 star-forming galaxies ...selected from the VANDELS survey at 3.85 ≤ zspec ≤ 4.95 (〈zspec〉 = 4.36). By combining measurements of H$\, \alpha$ equivalent width $(W_{\rm {\lambda }}(\rm {H\, \alpha }))$ derived from broad-band photometry with measurements of Ly$\, \alpha$ equivalent width $(W_{\rm {\lambda }}(\rm {Ly\, \alpha }))$ from the VANDELS spectra, we individually estimate $f_{\rm {esc}}^{\rm {Ly\alpha }}$ for our full sample. In agreement with previous studies, we find a positive correlation between $W_{\rm {\lambda }}(\rm {Ly\, \alpha })$ and $f_{\rm {esc}}^{\rm {Ly\alpha }}$, with $f_{\rm {esc}}^{\rm {Ly\alpha }}$ increasing from $f_{\rm {esc}}^{\rm {Ly\alpha }}\simeq 0.04$ at $W_{\rm {\lambda }}(\rm {Ly\, \alpha })=10$ Å to $f_{\rm {esc}}^{\rm {Ly\alpha }}\simeq 0.1$ at $W_{\rm {\lambda }}(\rm {Ly\, \alpha })=25$ Å. For the first time at z ≃ 4–5, we investigate the relationship between $f_{\rm {esc}}^{\rm {Ly\alpha }}$ and $f_{\rm {esc}}^{\rm {LyC}}$ using $f_{\rm {esc}}^{\rm {LyC}}$ estimates derived using the equivalent widths of low-ionization, far-ultraviolet absorption lines in composite VANDELS spectra. Our results indicate that $f_{\rm {esc}}^{\rm {LyC}}$ rises monotonically with $f_{\rm {esc}}^{\rm {Ly\alpha }}$, following a relation of the form $f_{\rm {esc}}^{\rm {LyC}}$$\simeq 0.15^{+0.06}_{-0.04}$$f_{\rm {esc}}^{\rm {Ly\alpha }}$. Based on composite spectra of sub-samples with approximately constant Wλ(Lyα), but widely different $f_{\rm {esc}}^{\rm {Ly\alpha }}$, we demonstrate that the $f_{\rm {esc}}^{\rm {LyC}}$−$f_{\rm {esc}}^{\rm {Ly\alpha }}$correlation is not driven by a secondary correlation between $f_{\rm {esc}}^{\rm {Ly\alpha }}$ and Wλ(Lyα). The observed $f_{\rm {esc}}^{\rm {LyC}}$−$f_{\rm {esc}}^{\rm {Ly\alpha }}$ correlation is in good qualitative agreement with theoretical predictions and provides further evidence that estimates of $f_{\rm {esc}}^{\rm {LyC}}$ within the Epoch of Reionization should be based on proxies sensitive to neutral gas density/geometry and dust attenuation.
ABSTRACT
We present a spectrophotometric study of a mass-complete sample of quiescent galaxies at 1.0 < z < 1.3 with $\mathrm{log_{10}}(M_{\star }/\mathrm{{\rm M}_{\odot }}) \ge 10.3$ drawn from the ...VANDELS survey, exploring the relationship between stellar mass, age, and star-formation history. Within our sample of 114 galaxies, we derive a stellar–mass versus stellar–age relation with a slope of $1.20^{+0.28}_{-0.27}$ Gyr per decade in stellar mass. When combined with recent literature results, we find evidence that the slope of this relation remains consistent over the redshift interval 0 < z < 4. The galaxies within the VANDELS quiescent sample display a wide range of star-formation histories, with a mean quenching time-scale of 1.4 ± 0.1 Gyr. We also find a large scatter in the quenching time-scales of the VANDELS quiescent galaxies, in agreement with previous evidence that galaxies at z ∼ 1 cease star formation via multiple mechanisms. We then focus on the oldest galaxies in our sample, finding that the number density of galaxies that quenched before z = 3 with stellar masses $\mathrm{log_{10}}(M_{\star }/\mathrm{{\rm M}_{\odot }}) \ge 10.6$ is $1.12_{-0.72}^{+1.47} \times 10^{-5} \ \mathrm{Mpc}^{-3}$. Although uncertain, this estimate is in good agreement with the latest observational results at 3 < z < 4, tentatively suggesting that neither rejuvenation nor merger events are playing a major role in the evolution of the oldest massive quiescent galaxies within the redshift interval 1 < z < 3.
ABSTRACT We present an analysis of the ultraviolet (UV) continuum slopes (β) for a sample of 172 galaxy candidates at 8 < zphot < 16 selected from a combination of JWST NIRCam imaging and ...COSMOS/UltraVISTA ground-based near-infrared imaging. Focusing primarily on a new sample of 121 galaxies at 〈z〉 ≃ 11 selected from ≃ 320 arcmin2 of public JWST imaging data across 15 independent data sets, we investigate the evolution of β in the galaxy population at z ≥ 9. We find a significant trend between β and redshift, with the inverse-variance weighted mean UV slope evolving from 〈β〉 = −2.17 ± 0.06 at z = 9.5 to 〈β〉 = −2.59 ± 0.06 at z = 11.5. Based on a comparison with stellar population models including nebular continuum emission, we find that at z > 10.5 the average UV continuum slope is consistent with the intrinsic blue limit of dust-free stellar populations (βint ≃ −2.6). These results suggest that the moderately dust-reddened galaxy population at z < 10 was essentially unattenuated at z ≃ 11. The extremely blue galaxies being uncovered at z > 10 place important constraints on dust attenuation in galaxies in the early Universe, and imply that the already observed galaxy population is likely supplying an ionizing photon budget capable of maintaining ionized intergalactic medium fractions of ≳ 5 per cent at z ≃ 11.
Mutualistic interactions are diverse and widespread and often involve multispecies guilds of mutualists competing for access to one or more partner species. Despite the ubiquity of these ...interactions, we know little about the dynamics of competition and coexistence within these guilds or how interactions between mutualists and their shared resource (the partner species) may influence these dynamics. In this article, we review the evidence for interspecific competition for partners within mutualist guilds in both plant‐pollinator and ant‐myrmecophyte systems. We then review evidence for the operation of different coexistence mechanisms within these guilds and discuss how the dynamics of competition and coexistence may be uniquely shaped by multispecies mutualist interactions. In particular, we note that adaptive and plastic responses by mutualists to variation in partner quality are likely to play an important role in determining these dynamics. We summarize by considering the ecological conditions that are likely to restrict or promote species coexistence within mutualist guilds. We suggest that these guilds may provide powerful model systems for exploring multiple mechanisms of species coexistence, and we discuss how these mechanisms may be modified by evolutionary adaptation.
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