Mass loss processes are a key uncertainty in the evolution of massive stars. They determine the amount of mass and angular momentum retained by the star, thus influencing its evolution and ...presupernova structure. Because of the high complexity of the physical processes driving mass loss, stellar evolution calculations must employ parametric algorithms, and usually only include wind mass loss. We carried out an extensive parameter study of wind mass loss and its effects on massive star evolution using the open-source stellar evolution code MESA. We provide a systematic comparison of wind mass loss algorithms for solar-metallicity, nonrotating, single stars in the initial mass range of 15 M⊙ to 35 M⊙. We consider combinations drawn from two hot phase (i.e., roughly the main sequence) algorithms, three cool phase (i.e., post-main-sequence) algorithms, and two Wolf-Rayet mass loss algorithms. We discuss separately the effects of mass loss in each of these phases. In addition, we consider linear wind efficiency scale factors of 1, 0.33, and 0.1 to account for suggested reductions in mass loss rates due to wind inhomogeneities. We find that the initial to final mass mapping for each zero-age main-sequence (ZAMS) mass has a ~ 50% uncertainty if all algorithm combinations and wind efficiencies are considered. The ad-hoc efficiency scale factor dominates this uncertainty. While the final total mass and internal structure of our models vary tremendously with mass loss treatment, final luminosity and effective temperature are much less sensitive for stars with ZAMS mass ≲ 30 M⊙. This indicates that uncertainty in wind mass loss does not negatively affect estimates of the ZAMS mass of most single-star supernova progenitors from pre-explosion observations. Our results furthermore show that the internal structure of presupernova stars is sensitive to variations in both main sequence and post main-sequence mass loss. The compactness parameter ξ ∝ ℳ /R(ℳ) has been identified as a proxy for the “explodability” of a given presupernova model. We find that ξ varies by as much as 30% for models of the same ZAMS mass evolved with different wind efficiencies and mass loss algorithm combinations. This suggests that the details of the mass loss treatment might bias the outcome of detailed core-collapse supernova calculations and the predictions for neutron star and black hole formation.
We present a state-of-the-art scenario for newly born magnetars as strong sources of gravitational waves (GWs) in the early days after formation. We address several aspects of the astrophysics of ...rapidly rotating, ultra-magnetized neutron stars (NSs), including early cooling before transition to superfluidity, the effects of the magnetic field on the equilibrium shape of NSs, the internal dynamical state of a fully degenerate, oblique rotator and the strength of the electromagnetic torque on the newly born NS. We show that our scenario is consistent with recent studies of supernova remnant surrounding Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) in the Galaxy that constrains the electromagnetic energy input from the central NS to be ≤ 1051 erg. We further show that if this condition is met, then the GW signal from such sources is potentially detectable with the forthcoming generation of GW detectors up to Virgo cluster distances where an event rate ∼1 yr−1 can be estimated. Finally, we point out that the decay of an internal magnetic field in the 1016 G range couples strongly with the NS cooling at very early stages, thus significantly slowing down both processes: the field can remain this strong for at least 103 yr, during which the core temperature stays higher than several times 108 K.
This chapter reviews evidence for functional connections of the somatosensory and auditory systems at the very lowest levels of the nervous system. Neural inputs from the dosal root and trigeminal ...ganglia, as well as their brain stem nuclei, cuneate, gracillis and trigeminal, terminate in the cochlear nuclei. Terminations are primarily in the shell regions surrounding the cochlear nuclei but some terminals are found in the magnocellular regions of cochlear nucleus. The effects of stimulating these inputs on multisensory integration are shown as short and long-term, both suppressive and enhancing. Evidence that these projections are glutamatergic and are altered after cochlear damage is provided in the light of probable influences on the modulation and generation of tinnitus.
► The cochlear nucleus receives non-auditory as well as auditory inputs. ► Many of these inputs arise in the somatosensory system. ► Somatosensory inputs to the cochlear nucleus are glutamatergic. ► Somatosensory inputs to the cochlear nucleus are enhanced after cochlear damage. ► Enhanced somatosensory input may lead to hyperactivity that represents tinnitus.
The Introduction word by the thematic editor of the issue reveals the main current tasks related to the challenges of growing
up individuals with autism spectrum disorders. A brief analysis of the ...content of thematic publications included in the current issue of the journal is carried out. A new rubric “Remote support for people with autism” introduced in connection with changes in living conditions caused by the COVID-19 epidemic is presented.
Во вступительном слове тематического редактора раскрыты основные актуальные задачи, связанные с проблемой взросления детей с расстройствами аутистического спектра. Проводится краткий анализ содержания тематических публикаций, вошедших в текущий номер журнала. Представлена новая рубрика «Дистанционная поддержка людей с аутизмом», появившаяся в связи с изменениями жизненных условий, вызванными эпидемией COVID-19.
ABSTRACT We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii ...2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ∼2 days after their first optical peaks. Significant γ-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longer-duration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the time spans of the observed γ-rays. The γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT are discussed.
A necessary requirement for multisensory integration is the convergence of pathways from different senses. The dorsal cochlear nucleus (DCN) receives auditory input directly via the VIIIth nerve and ...somatosensory input indirectly from the Vth nerve via granule cells. Multisensory integration may occur in DCN cells that receive both trigeminal and auditory nerve input, such as the fusiform cell. We investigated trigeminal system influences on guinea pig DCN cells by stimulating the trigeminal ganglion while recording spontaneous and sound‐driven activity from DCN neurons. A bipolar stimulating electrode was placed into the trigeminal ganglion of anesthetized guinea pigs using stereotaxic co‐ordinates. Electrical stimuli were applied as bipolar pulses (100 µs per phase) with amplitudes ranging from 10 to 100 µA. Responses from DCN units were obtained using a 16‐channel, four‐shank electrode. Current pulses were presented alone or preceding 100‐ or 200‐ms broadband noise (BBN) bursts. Thirty percent of DCN units showed either excitatory, inhibitory or excitatory–inhibitory responses to trigeminal ganglion stimulation. When paired with BBN stimulation, trigeminal stimulation suppressed or facilitated the firing rate in response to BBN in 78% of units, reflecting multisensory integration. Pulses preceding the acoustic stimuli by as much as 95 ms were able to alter responses to BBN. Bimodal suppression may play a role in attenuating body‐generated sounds, such as vocalization or respiration, whereas bimodal enhancement may serve to direct attention in low signal‐to‐noise environments.
Hearing impairment without threshold elevations can occur when there is damage to high‐threshold auditory nerve fibre synapses with cochlear inner hair cells. Instead, cochlear synaptopathy produces ...suprathreshold deficits, especially in older patients, which affect conversational speech. Given that listening in noise at suprathreshold levels presents significant challenges to the ageing population, we examined the effects of synaptopathy on tone‐in‐noise coding on the central recipients of auditory nerve fibres, i.e. the cochlear nucleus neurons. To induce synaptopathy, guinea pigs received a unilateral sound overexposure to the left ears. A separate group received sham exposures. At 4 weeks post‐exposure, thresholds had recovered but reduced auditory brainstem response wave 1 amplitudes and auditory nerve synapse loss remained on the left side. Single‐unit responses were recorded from several cell types in the ventral cochlear nucleus to pure‐tone and noise stimuli. Receptive fields and rate–level functions in the presence of continuous broadband noise were examined. The synaptopathy‐inducing noise exposure did not affect mean unit tone‐in‐noise thresholds, nor the tone‐in‐noise thresholds in each animal, demonstrating equivalent tone‐in‐noise detection thresholds to sham animals. However, synaptopathy reduced single‐unit responses to suprathreshold tones in the presence of background noise, particularly in the cochlear nucleus small cells. These data demonstrate that suprathreshold tone‐in‐noise deficits following cochlear synaptopathy are evident in the first neural station of the auditory brain, the cochlear nucleus neurons, and provide a potential target for assessment and treatment of listening‐in‐noise deficits in humans.
Key points
Recording from multiple central auditory neurons can determine tone‐in‐noise deficits in animals with quantified cochlear synapse damage.
Using this technique, we found that tone‐in‐noise thresholds are not altered by cochlear synaptopathy, whereas coding of suprathreshold tones‐in‐noise is disrupted.
Suprathreshold deficits occur in small cells and primary‐like neurons of the cochlear nucleus.
These data provide important insights into the mechanisms underlying difficulties associated with hearing in noisy environments.
figure legend A, unilateral noise exposure induces synaptopathy and temporary threshold shift (TTS) in guinea pigs. B, auditory thresholds of single units in the cochlear nucleus are shifted in background noise, and this shift is not affected by synaptopathy. C, suprathreshold firing rates are decreased by background sound, and this decrease is correlated with cochlear synaptopathy.
Context. The binary star system RS Ophiuchi is a recurrent nova, with outbursts occurring about every 22 years. It consists of a red giant star (RG) and a wind accreting white dwarf close to the ...Chandrasekhar limit. This system is considered a prime candidate for evolving into an SNIa. For its most recent outbursts in 1985 and 2006, exquisite multiwavelength observational data are available. Aims. Deeper physical insight is needed regarding the inter-outburst accretion phase and the dynamical effects of the subsequent nova explosion in order to improve the interpretation of the observed data and to shed light on whether the system is an SNIa progenitor. Methods. We present a 3D hydrodynamic simulation of the quiescent accretion with the subsequent explosive phase. Results. The computed circumstellar mass distribution in the quiescent phase is highly structured with a mass enhancement in the orbital plane of about a factor of 2 as compared to the poleward directions. The simulated nova remnant evolves aspherically, propagating faster toward the poles. The shock velocities derived from the simulations agree with those derived from observations. For $v_{\rm RG} = 20$ km s-1 and for nearly isothermal flows, we find that 10% of the mass lost by the RG is transfered to the WD. For an RG mass loss of $10^{-7}~M_{\odot}$ yr-1, the orbit of the system decays by 3% per million years. With the derived mass transfer rate, multi-cycle nova models provide a qualitatively correct recurrence time, amplitude, and fastness of the nova. Conclusions. Our 3D hydrodynamic simulations provide, along with the observations and nova models, the third ingredient for a deeper understanding of the recurrent novae of the RS Oph type. In combination with recent multi-cycle nova models, our results suggest that the WD in RS Oph will increase in mass. Several speculative outcomes then seem plausible. The WD may reach the Chandrasekhar limit and explode as an SN Ia. Alternatively, the mass loss of the RG could result in a smaller Roch volume, a common envelope phase, and a narrow WD + WD system. Angular momentum loss due to gravitational wave emission could trigger the merger of the two WDs and – perhaps – an SN Ia via the double degenerate scenario.
Both asthma and obesity are large and growing public health issues. Mounting evidence now implicates obesity as a major risk factor for asthma, thus linking these 2 major epidemics. Moreover, both in ...human subjects and in mice, obesity appears to predispose toward airway hyperresponsiveness. This review describes potential mechanisms whereby obesity might modify airway smooth muscle function to explain these observations. These mechanisms include both static and dynamic mechanical factors attributable to decreases in functional residual capacity and decreases in tidal volume that are observed in the obese. They include also obesity-related changes in lung development, chronic systemic inflammation (including increased serum levels of inflammatory cytokines and chemokines), and adipocyte-derived factors, including leptin, adiponectin, and plasminogen activator inhibitor.
ABSTRACT
On 2021 August 8, the recurrent nova RS Ophiuchi (RS Oph) erupted again, after an interval of 15.5 yr. Regular monitoring by the Neil Gehrels Swift Observatory began promptly, on August 9.9 ...(0.37 d after the optical peak), and continued until the source passed behind the Sun at the start of November, 86 d later. Observations then restarted on day 197, once RS Oph emerged from the Sun constraint. This makes RS Oph the first Galactic recurrent nova to have been monitored by Swift throughout two eruptions. Here we investigate the extensive X-ray data sets between 2006 and 2021, as well as the more limited data collected by the European X-ray Observatory Satellite (EXOSAT) in 1985. The hard X-rays arising from shock interactions between the nova ejecta and red giant wind are similar following the last two eruptions. In contrast, the early supersoft source (SSS) in 2021 was both less variable and significantly fainter than in 2006. However, 0.3–1 keV light curves from 2021 reveal a 35 s quasi-periodic oscillation consistent in frequency with the 2006 data. The Swift X-ray spectra from 2021 are featureless, with the soft emission typically being well parametrized by a simple blackbody, while the 2006 spectra showed much stronger evidence for superimposed ionized absorption edges. Considering the data after day 60 following each eruption, during the supersoft phase the 2021 spectra are hotter, with smaller effective radii and lower wind absorption, leading to an apparently reduced bolometric luminosity. We explore possible explanations for the gross differences in observed SSS behaviour between the 2006 and 2021 outbursts.
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