Abstract
We present a comprehensive study of 29 short gamma-ray bursts (SGRBs) observed ≈0.8−60 days postburst using Chandra and XMM-Newton. We provide the inferred distributions of the SGRB jet ...opening angles and true event rates to compare against neutron star merger rates. We perform a uniform analysis and modeling of their afterglows, obtaining 10 opening angle measurements and 19 lower limits. We report on two new opening angle measurements (SGRBs 050724A and 200411A) and eight updated values, obtaining a median value of 〈
θ
j
〉 ≈ 6.°1 −3.°2, +9.°3 (68% confidence on the full distribution) from jet measurements alone. For the remaining events, we infer
θ
j
≳ 0.°5–26°. We uncover a population of SGRBs with wider jets of
θ
j
≳ 10° (including two measurements of
θ
j
≳ 15°), representing ∼28% of our sample. Coupled with multiwavelength afterglow information, we derive a total true energy of 〈
E
true,tot
〉 ≈ 10
49
–10
50
erg, which is consistent with magnetohydrodynamic jet launching mechanisms. Furthermore, we determine a range for the beaming-corrected event rate of
R
true
≈
360
−
1800
Gpc
−3
yr
−1
, set by the inclusion of a population of wide jets on the low end, and the jet measurements alone on the high end. From a comparison with the latest merger rates, our results are consistent with the majority of SGRBs originating from binary neutron star mergers. However, our inferred rates are well above the latest neutron star–black hole merger rates, consistent with at most a small fraction of SGRBs originating from such mergers.
We present the discovery of the optical afterglow and host galaxy of the Swift short-duration gamma-ray burst (SGRB) GRB 181123B. Observations with Gemini-North starting 9.1 hr after the burst reveal ...a faint optical afterglow with i 25.1 mag at an angular offset of 0 59 0 16 from its host galaxy. Using grizYJHK observations, we measure a photometric redshift of the host galaxy of . From a combination of Gemini and Keck spectroscopy of the host galaxy spanning 4500-18000 , we detect a single emission line at 13390 , inferred as Hβ at z = 1.754 0.001 and corroborating the photometric redshift. The host galaxy properties of GRB 181123B are typical of those of other SGRB hosts, with an inferred stellar mass of 9.1 × 109 M , a mass-weighted age of 0.9 Gyr, and an optical luminosity of 0.9L*. At z = 1.754, GRB 181123B is the most distant secure SGRB with an optical afterglow detection and one of only three at z > 1.5. Motivated by a growing number of high-z SGRBs, we explore the effects of a missing z > 1.5 SGRB population among the current Swift sample on delay time distribution (DTD) models. We find that lognormal models with mean delay times of 4-6 Gyr are consistent with the observed distribution but can be ruled out to 95% confidence, with an additional one to five Swift SGRBs recovered at z > 1.5. In contrast, power-law models with ∝t−1 are consistent with the redshift distribution and can accommodate up to 30 SGRBs at these redshifts. Under this model, we predict that 1/3 of the current Swift population of SGRBs is at z > 1. The future discovery or recovery of existing high-z SGRBs will provide significant discriminating power on their DTDs and thus their formation channels.
Several published polymerase chain reaction (PCR) primers to identify Pseudomonas syringae pv. actinidiae, the causal organism of bacterial canker of kiwifruit, were found not to be specific. Two new ...sets of PCR primers, PsaF1/R2 and PsaF3/R4, were designed to be complementary to a portion of the 16S-23S rDNA intertranscribed spacer (ITS) regions. These primers amplified a DNA fragment from strains of P. syringae pv. actinidiae, but not from 56 strains of bacteria from six genera and 17 species, except for a strain of the tea pathogen, P. syringae pv. theae. When tested against DNA extracted from a further 20 strains from Japan, Korea, Italy and the USA deposited in culture collections as P. syringae pv. actinidiae, all except six cultures produced the expected product of 280 bp with PsaF1/R2 and 175 bp with PsaF3/R4. Results of multilocus sequence analysis using five housekeeping genes (gyrB, acnB, rpoD, pgi and cts) showed that none of these six strains was phylogenetically similar to P. syringae pv. actinidiae. In contrast to the P. syringae pv. actinidiae type strain, these strains were positive in the determinative tests for ice nucleation and syringomycin production. It is suggested that these six strains were incorrectly identified as P. syringae pv. actinidiae. It was not possible to distinguish P. syringae pv. actinidiae from the phylogenetically similar P. syringae pv. theae using the ITS, gyrB, acnB, rpoD, pgi or cts gene regions to design PCR primers. Because P. syringae pv. theae is unlikely to be found on kiwifruit, primers PsaF1/R2 and PsaF3/R4 are recommended for screening bacteria isolated from kiwifruit tissue.
Resistance to electrical tree-induced degradation is one of the common ways of characterising solid dielectrics. This paper presents experimentally obtained distinct time-evolution patterns of ...electrical tree partial discharges (PDs) in epoxy nanocomposites of Magnesia, Silica and Alumina. Plots of the electrical tree PD magnitudes recorded every second from inception to complete failure show that the PD magnitudes in the nanodielectric epoxy are generally smaller than in neat epoxy. Furthermore the PD magnitudes and phase-resolved-patterns (PDPRP) in the nanodielectric epoxy evolve through distinct classes as the trees propagate to complete failure. The experimental findings confirm existing knowledge and give new insights into the understanding of electrical treeing phenomena in nanodielectrics.
Some strains of Pseudomonas syringae pv. actinidiae (Psa), the causal agent of bacterial canker of kiwifruit, produce plant hormones and toxins which alter the plant hormonal balance and result in ...the suppression of the salicylic acid (SA)‐dependent plant defences. To determine whether Psa could be affected by stimulation of the SA pathway, Actinidia deliciosa and A. chinensis were treated with compounds which interfere with this pathway, then inoculated with Psa. On A. deliciosa, compounds which stimulate the SA pathway SA, or its synthetic analogue, acibenzolar‐S‐methyl (ASM) or close stomata (ABA) resulted in disease reduction, while methyl‐jasmonate (MJA) or ethylene increased disease development. On A. chinensis, similar results were obtained except that SA and MJA did not affect disease development. Reduction in disease incidence and severity on A. deliciosa using ASM was correlated with a superoxide burst, the formation of necrotic spots and callose deposition, while on A. chinensis no superoxide burst or callose deposition was detected. Genes involved in plant–pathogen interactions were induced after treatment with ASM in A. deliciosa and, to a lesser extent, in A. chinensis. Those differences in gene expression and physiological responses after treatment with ASM are consistent with the different susceptibility to Psa observed between A. chinensis and A. deliciosa.
Summary
Background
Antenatal factors including maternal diet may predispose to airway disease, possibly by impacting on fetal airway development.
Objective
This cohort study tested the hypothesis ...that maternal vitamin D and E status in early pregnancy is associated with airway epithelial cell (AEC) responses in new born infants and examined constitutive and TNFα/IL‐1β, house dust mite (HDM) extract or lipopolysaccharide (LPS)‐stimulated neonatal AEC responses in vitro.
Methods
Maternal dietary vitamin D and E intakes (plasma 25OHD3 or α‐tocopherol) were characterized at 10–12 weeks gestation. Neonatal nasal AECs were collected soon after birth and cultured to tertiary passage. Constitutive and stimulated – TNFα/IL‐1β, HDM extract or LPS – secretory responses (VEGF, RANTES, MCP‐1, IL‐17A, IFN‐γ, GM‐CSF, eotaxin, MIP1‐α, MIP1‐β, ICAM, IL‐6, IL‐8, IL‐10, TNF) in 139 AEC cultures were quantified.
Results
AEC mediator release was greater following TNF‐α/IL‐1β, HDM or LPS stimulation compared to constitutive release. Increased maternal dietary vitamin D was associated with significant increases in IL‐10 release by AEC after stimulation with TNF‐α/IL‐1β (P = 0.024) or HDM (P = 0.049). Maternal plasma α‐tocopherol at 10–12 weeks gestation was positively associated with MIP1α (Spearman's rho 0.242, P = 0.009) and IL‐3 (ρ 0.189, P = 0.043) responses after TNF‐α/IL‐1β stimulation and negatively associated with TNF (ρ ‐0.404, P = 0.011) and MIP1β (ρ ‐0.322, P = 0.046) responses after LPS stimulation.
Discussion
Neonatal AECs respond to pro‐inflammatory and allergenic stimuli in vitro demonstrating their potential to function as components of the innate immune response. Our findings suggest that associations exist between maternal micronutrient intake during early pregnancy and aspects of stimulated neonatal airway epithelial cell secretory function that may in turn impact on the development of asthma and/or allergic rhinitis in later life.
Abstract
We present X-ray and multiband optical observations of the afterglow and host galaxy of GRB 180418A, discovered by Swift/BAT and Fermi/GBM. We present a reanalysis of the GBM and BAT data ...deriving durations of the prompt emission of
T
90
≈ 2.56 and 1.90 s, respectively. Modeling the Fermi/GBM catalog of 1405 bursts (2008–2014) in the hardness–
T
90
plane, we obtain a probability of ≈60% that GRB 180418A is a short-hard burst. From a combination of Swift/XRT and Chandra observations, the X-ray afterglow is detected to ≈38.5 days after the burst and exhibits a single power-law decline with
F
X
∝
t
−0.98
. Late-time Gemini observations reveal a faint
r
≈ 25.69 mag host galaxy at an angular offset of ≈0.″16. At the likely redshift range of
z
≈ 1–2.25, we find that the X-ray afterglow luminosity of GRB 180418A is intermediate between short and long gamma-ray bursts (GRBs) at all epochs during which there are contemporaneous data and that GRB 180418A lies closer to the
E
γ
,peak
–
E
γ
,iso
correlation for short GRBs. Modeling the multiwavelength afterglow with the standard synchrotron model, we derive the burst explosion properties and find a jet opening angle of
θ
j
≳ 9°–14°. If GRB 180418A is a short GRB that originated from a neutron star merger, it has one of the brightest and longest-lived afterglows along with an extremely faint host galaxy. If, instead, the event is a long GRB that originated from a massive star collapse, it has among the lowest-luminosity afterglows and lies in a peculiar space in terms of the hardness–
T
90
and
E
γ
,peak
–
E
γ
,iso
planes.
Two patients from Eritrea, recently arrived in the Netherlands, presented with fever and were investigated for malaria. Bloodfilms showed spirochetes but no blood parasites. Louse-borne relapsing ...fever caused by Borrelia recurrentis was diagnosed. Treatment was complicated by severe Jarisch-Herxheimer reactions in both patients. Physicians should be aware of the possibility of B. recurrentis infection in migrant populations who travel under crowded conditions, especially after passing through endemic areas such as Ethiopia and neighbouring countries.
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