We have performed an ecliptic survey of the Kuiper belt, with an areal coverage of 8.9 square degrees to a 50% limiting magnitude of
r
Sloan
′
=
24.7
, and have detected 88 Kuiper belt objects, ...roughly half of which received follow-up 1–2 months after detection. Using this survey data alone, we have measured the luminosity function of the Kuiper belt, thus avoiding any biases that might come from the inclusion of other observations. We have found that the
Cold population defined as having inclinations less than 5° has a luminosity function slope
α
Cold
=
0.82
±
0.23, and is different from the
Hot population, which has inclinations greater than 5° and a luminosity function slope
α
Hot
=
0.35
±
0.21. As well, we have found that those objects closer than 38
AU have virtually the same luminosity function slope as the
Hot population. This result, along with similar findings of past surveys demonstrates that the dynamically
Cold Kuiper belt objects likely have a steep size distribution, and are unique from all of the excited populations which have much shallower distributions. This suggests that the dynamically excited population underwent a different accretion history and achieved a more evolved state of accretion than the
Cold population. As well, we discuss the similarities of the
Cold and
Hot populations with the size distributions of other planetesimal populations. We find that while the Jupiter family comets and the scattered disk exhibit similar size distributions, a power-law extrapolation to small sizes for the scattered disk cannot account for the observed influx of comets. As well, we have found that the Jupiter Trojan and
Hot populations cannot have originated from the same parent population, a result that is difficult to reconcile with scattering models similar to the NICE model. We conclude that the similarity between the size distributions of the
Cold population and the Jupiter Trojan population is a striking coincidence.
ABSTRACT
Discovering exoplanets orbiting young Suns can provide insight into the formation and early evolution of our own solar system, but the extreme magnetic activity of young stars obfuscates ...exoplanet detection. Here we monitor the long-term magnetic field and chromospheric activity variability of the young solar analogue V889 Her, model the activity-induced radial velocity variations, and evaluate the impacts of extreme magnetism on exoplanet detection thresholds. We map the magnetic field and surface brightness for 14 epochs between 2004 and 2019. Our results show potential 3–4 yr variations of the magnetic field that evolves from weak and simple during chromospheric activity minima to strong and complex during activity maxima but without any polarity reversals. A persistent, temporally varying polar spot coexists with weaker, short-lived lower-latitude spots. Due to their different decay time-scales, significant differential rotation, and the limited temporal coverage of our legacy data, we were unable to reliably model the activity-induced radial velocity using Gaussian Process regression. Doppler Imaging can be a useful method for modelling the magnetic activity jitter of extremely active stars using data with large phase gaps. Given our data and using Doppler Imaging to filter activity jitter, we estimate that we could detect Jupiter-mass planets with orbital periods of $\sim$3 d. A longer baseline of continuous observations is the best observing strategy for the detection of exoplanets orbiting highly active stars.
In many tissues, including brain, prolactin action is predominantly mediated by the Janus kinase/signal transducer and activator of transcription (STAT) signal transduction pathway, leading to ...changes in gene transcription. However, prolactin can also exert rapid actions on electrical activity of hypothalamic neurons. Here, we investigate whether both responses occur in a single cell type, focusing on three specific populations known to be influenced by prolactin: GnRH neurons, tuberoinfundibular dopamine (TIDA) neurons, and neurons in the anteroventral-periventricular nucleus in female mice. We performed phosphorylated STAT5 (pSTAT5) immunohistochemistry to identify prolactin-responsive neurons after in vivo prolactin treatment. In addition, we carried out in vitro electrophysiology in slices from transgenic mice expressing green fluorescent protein driven by the GnRH or tyrosine hydroxylase promoters as well as from C57BL/6J mice to assess acute electrical responses to prolactin. Approximately 88% of TIDA neurons expressed pSTAT5 in diestrous mice, rising to 97% after prolactin treatment. All TIDA neurons also showed a rapid increase in firing rate after prolactin treatment. In contrast, very few GnRH neurons (11%) showed pSTAT5 in response to prolactin, and none showed a change in electrical activity. Finally, in the anteroventral-periventricular nucleus, most neurons (69%) responded to prolactin treatment with an increase in pSTAT5, but only 2/38 (∼5%) showed changes in electrical activity in response to prolactin. These observations show that prolactin recruits different combinations of electrical and transcriptional responses in neurons depending upon their anatomical location and phenotype. This may be critical in establishing appropriate responses to prolactin under different physiological conditions.
Leaching of nitrate from fertilisers diminishes nitrogen use efficiency (the portion of nitrogen used by a plant) and is a major source of agricultural pollution. To improve nitrogen capture, grasses ...such as brachiaria are increasingly used, especially in South America and Africa, as a cover crop, either via intercropping or in rotation. However, the complex interactions between soil structure, nitrogen and the root systems of maize and different species of forage grasses remain poorly understood. This study explored how soil structure modification by the roots of maize (Zea maize), palisade grass (Brachiaria brizantha cv. Marandu) and ruzigrass (Brachiaria ruziziensis) affected nitrate leaching and retention, measured via chemical breakthrough curves. All plants were found to increase the rate of nitrate transport suggesting root systems increase the tendency for preferential flow. The greater density of fine roots produced by palisade grass, subtly decreased nitrate leaching potential through increased complexity of the soil pore network assessed with X-ray Computed Tomography. A dominance of larger roots in ruzigrass and maize increased nitrate loss through enhanced solute flow bypassing the soil matrix. These results suggest palisade grass could be a more efficient nitrate catch crop than ruzigrass (the most extensively used currently in countries such as Brazil) due to retardation in solute flow associated with the fine root system and the complex pore network.
Major depressive disorder is common in people with asthma. Yet, few studies have evaluated depression treatment in those with asthma.
To explore the relationship between antidepressant use, ...depressive symptoms, and asthma control, pooled data from 3 randomized trials of either citalopram or escitalopram were assessed.
Linear fixed effects and binary logistic regression analyses were conducted with between-subject covariates including treatment group, (original) study, and demographics. The within-subject effect of visit, and a treatment group-visit (between-within) interaction effect, were also evaluated. Analyses were repeated in a high asthma exacerbation subgroup having at least 3 oral corticosteroid bursts in the previous 12 months. Outcomes included the Hamilton rating scale for depression (HAM-D
), the 7-item asthma control questionnaire (ACQ), and oral corticosteroid use (yes or no).
In the pooled sample (n = 255), the antidepressant treatment group exhibited lower HAM-D
overall (P ≤ .001) and a lower likelihood for oral corticosteroid use (P ≤ .001) relative to the placebo group. In the high-exacerbation subgroup (n = 96), treatment group participants had lower overall asthma control questionnaire (P = .004) and HAM-D
scores (P ≤ .001), and a lower likelihood of oral corticosteroid use (P = .003), relative to placebo participants. All treatment group interaction effects were not significant.
Citalopram or escitalopram exhibited efficacy in reducing depressive symptoms and the need for rescue oral corticosteroids in patients with asthma and major depressive disorder. Future work should determine whether selective serotonin reuptake inhibitors are effective at improving asthma outcomes in those with asthma who are not depressed.
Clinicaltrials.gov Identifier: NCT00621946 and NCT01324700 (one study was conducted before ClinicalTrials.gov requirements).
Novel invertebrate‐killing compounds are required in agriculture and medicine to overcome resistance to existing treatments. Because insecticides and anthelmintics are discovered in phenotypic ...screens, a crucial step in the discovery process is determining the mode of action of hits. Visible whole‐organism symptoms are combined with molecular and physiological data to determine mode of action. However, manual symptomology is laborious and requires symptoms that are strong enough to see by eye. Here, we use high‐throughput imaging and quantitative phenotyping to measure Caenorhabditis elegans behavioral responses to compounds and train a classifier that predicts mode of action with an accuracy of 88% for a set of ten common modes of action. We also classify compounds within each mode of action to discover substructure that is not captured in broad mode‐of‐action labels. High‐throughput imaging and automated phenotyping could therefore accelerate mode‐of‐action discovery in invertebrate‐targeting compound development and help to refine mode‐of‐action categories.
Synopsis
A combination of imaging and machine learning is used to predict compound mode of action using the unique behavioural responses of the roundworm C. elegans to different pesticides and anthelmintics.
Insecticides affect phenotypes in multiple behavioural dimensions.
Compounds with the same mode of action have similar effects on behaviour.
Combining classifiers by voting enables mode of action prediction.
The approach allows mode of action deconvolution within classes.
A combination of imaging and machine learning is used to predict compound mode of action using the unique behavioural responses of the roundworm C. elegans to different pesticides and anthelmintics.
Ocular exposure to early morning room light can significantly advance the timing of the human circadian pacemaker. The resetting
response to such light has a non-linear relationship to illuminance. ...The dose-response relationship of the human circadian
pacemaker to late evening light of dim to moderate intensity has not been well established.
Twenty-three healthy young male and female volunteers took part in a 9 day protocol in which a single experimental light exposure6.5
h in duration was given in the early biological night. The effects of the light exposure on the endogenous circadian phase
of the melatonin rhythm and the acute effects of the light exposure on plasma melatonin concentration were calculated.
We demonstrate that humans are highly responsive to the phase-delaying effects of light during the early biological night
and that both the phase resetting response to light and the acute suppressive effects of light on plasma melatonin follow
a logistic dose-response curve, as do many circadian responses to light in mammals.
Contrary to expectations, we found that half of the maximal phase-delaying response achieved in response to a single episode
of evening bright light (â¼9000 lux (lx)) can be obtained with just over 1 % of this light (dim room light of â¼100 lx). The
same held true for the acute suppressive effects of light on plasma melatonin concentrations. This indicates that even small
changes in ordinary light exposure during the late evening hours can significantly affect both plasma melatonin concentrations
and the entrained phase of the human circadian pacemaker.
Abstract
The observation of X-rays during quiescence from transiently accreting neutron stars provides unique clues about the nature of dense matter. This, however, requires extensive modeling of the ...crusts and matching the results to observations. The pycnonuclear fusion reaction rates implemented in these models are theoretically calculated by extending phenomenological expressions and have large uncertainties spanning many orders of magnitude. We present the first sensitivity studies of these pycnonuclear fusion reactions in realistic network calculations. We also couple the reaction network with the thermal evolution code
dStar
to further study their impact on the neutron star cooling curves in quiescence. Varying the pycnonuclear fusion reaction rates alters the depth at which nuclear heat is deposited although the total heating remains constant. The enhancement of the pycnonuclear fusion reaction rates leads to an overall shallower deposition of nuclear heat. The impurity factors are also altered depending on the type of ashes deposited on the crust. These total changes correspond to a variation of up to 9 eV in the modeled cooling curves. While this is not sufficient to explain the shallow heat source, it is comparable to the observational uncertainties and can still be important for modeling the neutron star crust.
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