We present the discovery of ASASSN-18ey (MAXI J1820+070), a new black hole low-mass X-ray binary (LMXB) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). A week after ASAS-SN ...discovered ASASSN-18ey as an optical transient, it was detected as an X-ray transient by MAXI/GCS. Here, we analyze ASAS-SN and Asteroid Terrestrial-impact Last Alert System pre-outburst optical light curves, finding evidence of intrinsic variability for several years prior to the outburst. While there was no long-term rise leading to the outburst, as has been seen in several other systems, the start of the outburst in the optical preceded that in the X-rays by 7.20 0.97 days. We analyze the spectroscopic evolution of ASASSN-18ey from pre-maximum to >100 days post-maximum. The spectra of ASASSN-18ey exhibit broad, asymmetric, double-peaked H emission. The Bowen blend (λ 4650 ) in the post-maximum spectra shows highly variable double-peaked profiles, likely arising from irradiation of the companion by the accretion disk, typical of low-mass X-ray binaries. The optical and X-ray luminosities of ASASSN-18ey are consistent with black hole low-mass X-ray binaries, both in outburst and quiescence.
A
bstract
We address the impact of a modified
W ℓν
coupling on a wide range of observables, such as τ leptonic and mesonic decays, leptonic decays of pseudoscalar mesons, as well as semileptonic ...meson decays. In particular, we concentrate on deviations from lepton flavour universality, focusing on the ratios
R
P
= Γ(
P
→
ℓν
)
/
Γ(
P
→
ℓ′ν
), with
P
=
K,π,D,D
s
,
R
(
D
) = Γ(
B
+
→
Dτ
+
ν
)
/
Γ(
B
+
→
Dℓ
+
ν
),
R
τ
= Γ(
τ
→
μνν
)
/
Γ(
τ
→ eνν),
= Γ(
τ
→
Pν
)
/
Γ(
P
→
ℓν
), and BR(
B
→
τν
). We further consider leptonic gauge boson decays, such as
W
→
ℓν
and
Z
→
νν
. For all the above observables, we provide the corresponding complete analytical expressions, derived for the case of massive neutrinos. Working in the framework of the Standard Model extended by additional sterile fermions, which mix with the active (left-handed) neutrinos, we numerically study the impact of active-sterile mixings on the above mentioned observables.
Elastic and viscoelastic characterization of agar Nayar, V.T.; Weiland, J.D.; Nelson, C.S. ...
Journal of the mechanical behavior of biomedical materials,
March 2012, 2012-Mar, 2012-3-00, 20120301, Letnik:
7
Journal Article
Recenzirano
Agar is a biological polymer, frequently used in tissue engineering research; due to its consistency, controllable size, and concentration-based properties, it often serves as a representative ...material for actual biological tissues. In this study, nanoindentation was used to characterize both the time-independent and time-dependent response of agar samples having various concentrations (0.5%–5.0% by weight). Quasi-static indentation was performed at different loads and depths using both open- and closed-loop controls. Reduced modulus (Er) values change with agar concentration, ranging from ∼30 kPa for 0.5% samples to ∼700 kPa for 5.0% samples, which is the same modulus range as usually encountered in soft biological materials. Dynamic indentation was performed to assess the effects of load, dynamic frequency and amplitude. Storage modulus values ranged from approximately 30 to 2300 kPa depending on agar concentration. Loss modulus remained consistently less than 30 kPa at all conditions, indicating a diminished damping response in agar.
Display omitted
► Instrumented nanoindentation characterizes soft biological materials with Er<1 MPa. ► Comparison of the effects of load as well as dynamic frequency and amplitude upon biological polymers. ► Quasi-static and dynamic measurements are compared for a range of soft biological polymers.
We present the discovery of PS18kh, a tidal disruption event discovered at the center of SDSS J075654.53+341543.6 (d 322 Mpc) by the Pan-STARRS Survey for Transients. Our data set includes ...pre-discovery survey data from Pan-STARRS, the All-sky Automated Survey for Supernovae, and the Asteroid Terrestrial-impact Last Alert System as well as high-cadence, multiwavelength follow-up data from ground-based telescopes and Swift, spanning from 56 days before peak light until 75 days after. The optical/UV emission from PS18kh is well-fit as a blackbody with temperatures ranging from T 12,000 K to T 25,000 K and it peaked at a luminosity of L 8.8 × 1043 erg s−1. PS18kh radiated E = (3.45 0.22) × 1050 erg over the period of observation, with (1.42 0.20) × 1050 erg being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked H emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the H line and its evolution. We find that at early times the high accretion rate leads the disk to emit a wind which modifies the shape of the line profile and makes it bell-shaped. At late times, the wind becomes optically thin, allowing the non-axisymmetric perturbations to show up in the line profile. The line-emitting portion of the disk extends from rin ∼ 60rg to an outer radius of rout ∼ 1400rg and the perturbations can be represented either as an eccentricity in the outer rings of the disk or as a spiral arm in the inner disk.
In the developed world, extreme prematurity is the leading cause of neonatal mortality and morbidity due to a combination of organ immaturity and iatrogenic injury. Until now, efforts to extend ...gestation using extracorporeal systems have achieved limited success. Here we report the development of a system that incorporates a pumpless oxygenator circuit connected to the fetus of a lamb via an umbilical cord interface that is maintained within a closed 'amniotic fluid' circuit that closely reproduces the environment of the womb. We show that fetal lambs that are developmentally equivalent to the extreme premature human infant can be physiologically supported in this extra-uterine device for up to 4 weeks. Lambs on support maintain stable haemodynamics, have normal blood gas and oxygenation parameters and maintain patency of the fetal circulation. With appropriate nutritional support, lambs on the system demonstrate normal somatic growth, lung maturation and brain growth and myelination.
Salmon recovery and the potential detrimental effects of dams on fish have been attracting national attention due to the environmental and economic implications. In recent years acoustic telemetry ...has been the primary method for studying salmon passage. However, the size of the existing transmitters limits the minimum size of fish that can be studied, introducing a bias to the study results. We developed the first acoustic fish transmitter that can be implanted by injection instead of surgery. The new injectable transmitter lasts four times longer and weighs 30% less than other transmitters. Because the new transmitter costs significantly less to use and may substantially reduce adverse effects of implantation and tag burden, it will allow for study of migration behavior and survival of species and sizes of fish that have never been studied before. The new technology will lead to critical information needed for salmon recovery and the development of fish-friendly hydroelectric systems.
Absence of a functional interferon-λ 4 (IFN-λ4) gene (IFNL4) predicts spontaneous resolution of acute hepatitis C virus (HCV) infections in regions with a predominance of genotype 1, whereas variants ...of the inosine triphosphate pyrophosphatase (ITPase) gene (ITPA) entailing reduced activity associate with increased sustained virologic response rates following some therapeutic regimens. This study aimed at investigating the impact of IFNL4 on acute HCV genotype 2 or 3 infections, and whether ITPase activity influenced outcome.
Two hundred and seven people who injected drugs (PWID) with documented anti-HCV seroconversion, and 57 PWID with reinfection with HCV were analyzed regarding IFNL4 (rs368234815 and rs12979860) and ITPA (rs1127354 and rs7270101), and longitudinally followed regarding HCV RNA.
The spontaneous clearance of HCV infection in anti-HCV seronegative PWID was enhanced when IFN-λ4 was absent (44% vs. 20% for IFNL4 TT/TT
rs1368234815
and ΔG
rs1368234815
respectively, p < .001; OR 3.2) across genotypes 1-3. The proportion lacking IFN-λ4 was further increased following resolution of repeated re-exposure to HCV (74% among re-infected participants who had cleared at least two documented HCV infections). ITPA genetic variants did not independently impact on the outcome, but among males lacking IFN-λ4, reduced ITPase activity markedly augmented the likelihood of resolution (65% vs. 29% for <100% and 100% ITPase activity, p = .006).
Absence of IFN-λ4 entails an enhanced likelihood of spontaneous resolution both following primary acute infection and repeated re-exposure to HCV across genotypes 1-3. Among men lacking IFN-λ4, reduced ITPase activity improved outcome.
Summary
Despite a rise in blood pressure, cerebral oxygenation decreases following phenylephrine administration, and we hypothesised that phenylephrine reduces cerebral oxygenation by activating ...cerebral α1 receptors. We studied patients on cardiopulmonary bypass during constant flow. Phenylephrine raised mean arterial pressure (α1‐mediated) from mean (SD) 69 (8) mmHg to 79 (8) mmHg; p = 0.001, and vasopressin raised mean arterial pressure (V1 mediated) from 69 (8) mmHg to 83 (6) mmHg; p = 0.001. Both drugs elicited a comparable decrease in cerebral oxygenation from 61 (7)% to 60 (7)%; p = 0.023 and 61 (8)% to 59 (8)%; p = 0.022, respectively. This implies that after phenylephrine or vasopressin administration, cerebral oxygenation declines as a result of cerebral vasoconstriction, due to either both cerebral α1 and V1 receptors being equipotentially activated or to an intrinsic myogenic mechanism of cerebral vasculature in reaction to blood pressure elevation.
International comparative studies, investigating whether disease incidence or prevalence rates differ between populations and, if so, which factors explain the observed differences, have made ...important contributions to the understanding of disease aetiology in many areas. In Phase I of the International Study of Asthma and Allergies in Childhood (ISAAC), the prevalence rates of symptoms of asthma, allergic rhinitis and atopic eczema in 13-14-yr-olds, assessed by standardised questionnaires, were found to differ >20-fold between the 155 study centres around the world. Phase II of ISAAC aims to identify determinants of these differences by studying informative populations. A detailed study protocol was developed for use in community-based random samples of children aged 9-11 yrs. The study modules include standardised questionnaires with detailed questions on the occurrence and severity of symptoms of asthma, allergic rhinitis and atopic eczema, their clinical management, and a broad range of previous and current exposure conditions. In addition, standardised protocols were applied for examination of flexural dermatitis, skin-prick testing, bronchial challenge with hypertonic saline, blood sampling for immunoglobulin E analyses and genotyping, and dust sampling for assessment of indoor exposures to allergens and endotoxin. To date, ISAAC II field work had been completed or started in 30 study centres in 22 countries. The majority of centres are in countries that participated in International Study of Asthma and Allergies in Childhood Phase I and reflect almost the full range of the observed variability in Phase I prevalence rates.
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