Glitches correspond to sudden jumps of rotation frequency ( ) and its derivative ( ) of pulsars, the origin of which remains not well understood yet, partly because the jump processes of most ...glitches are not well time-resolved. There are three large glitches of the Crab pulsar, detected in 1989, 1996, and 2017, which were found to have delayed spin-up processes before the normal recovery processes. Here we report two additional glitches of this pulsar that occurred in 2004 and 2011 for which we discovered delayed spin-up processes, and present refined parameters of the largest glitch, which occurred in 2017. The initial rising time of the glitch is determined as <0.48 hr. The two glitches that occurred in 2004 and 2011 had delayed spin-up time scales (τ1) of 1.7 0.8 days and 1.6 0.4 days, respectively. We also carried out a statistical study of these five glitches with observed spin-up processes. We find that the Δ versus relation of these five glitches is similar to those with no detected delayed spin-up process, indicating that they are similar to the others in nature except that they have larger amplitudes. For these five glitches, the amplitudes of the delayed spin-up process ( ) and recovery process (Δ d2), their time scales (τ1, τ2), and permanent changes in spin frequency (Δ p) and total frequency step (Δ g) have positive correlations. From these correlations, we suggest that the delayed spin-up processes are common for all glitches, but are too short and thus difficult to be detected for most glitches.
The mass concentration of black carbon (BC) particles in the
atmosphere has traditionally been quantified with two methods: as elemental
carbon (EC) concentrations measured by thermal–optical ...analysis and as
equivalent black carbon (eBC) concentrations when BC mass is derived from
particle light absorption coefficient measurements. Over the last decade,
ambient measurements of refractory black carbon (rBC) mass concentrations
based on laser-induced incandescence (LII) have become more common, mostly
due to the development of the Single Particle Soot Photometer (SP2)
instrument. In this work, EC and rBC mass concentration measurements from
field campaigns across several background European sites (Palaiseau,
Bologna, Cabauw and Melpitz) have been collated and examined to identify the
similarities and differences between BC mass concentrations measured by the
two techniques. All EC concentration measurements in PM2.5 were
performed with the EUSAAR-2 thermal–optical protocol. All rBC
concentration measurements were performed with SP2 instruments calibrated with the same
calibration material as recommended in the literature. The observed values
of median rBC-to-EC mass concentration ratios on the single-campaign level were
0.53, 0.65, 0.97, 1.20 and 1.29, respectively, and the geometric standard
deviation (GSD) was 1.5 when considering all data points from all five
campaigns. This shows that substantial systematic bias between these two
quantities occurred during some campaigns, which also contributes to the
large overall GSD. Despite considerable variability in BC properties and
sources across the whole dataset, it was not possible to clearly assign
reasons for discrepancies to one or the other method, both known to have
their own specific limitations and uncertainties. However, differences in
the particle size range covered by these two methods were identified as one
likely reason for discrepancies. Overall, the observed correlation between rBC and EC mass reveals a linear
relationship with a constant ratio, thus providing clear evidence that both
methods essentially quantify the same property of atmospheric aerosols,
whereas systematic differences in measured absolute values by up to a factor
of 2 can occur. This finding for the level of agreement between two current
state-of-the-art techniques has important implications for studies based
on BC mass concentration measurements, for example for the interpretation of
uncertainties in inferred BC mass absorption coefficient values, which are
required for modeling the radiative forcing of BC. Homogeneity between BC
mass determination techniques is also very important for moving towards a routine BC
mass measurement for air quality regulations.
We present the discovery of HD 221416 b, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. HD 221416 ...b (HIP 116158, TOI-197) is a bright (V = 8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 Hz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (R = 2.943 0.064 R ), mass (M = 1.212 0.074 M ), and age (4.9 1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a "hot Saturn" (Rp = 9.17 0.33 R⊕) with an orbital period of ∼14.3 days, irradiance of F = 343 24 F⊕, and moderate mass (Mp = 60.5 5.7 M⊕) and density ( p = 0.431 0.062 g cm−3). The properties of HD 221416 b show that the host-star metallicity-planet mass correlation found in sub-Saturns (4-8 R⊕) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to ∼15%, HD 221416 b is one of the best characterized Saturn-size planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology.
Abstract Receptor-activated Ca2+ influx is mediated largely by store-operated channels (SOCs). TRPC channels mediate a significant portion of the receptor-activated Ca2+ influx. However, whether any ...of the TRPC channels function as a SOC remains controversial. Our understanding of the regulation of TRPC channels and their function as SOCs is being reshaped with the discovery of the role of STIM1 in the regulation of Ca2+ influx channels. The findings that STIM1 is an ER resident Ca2+ binding protein that regulates SOCs allow an expanded and molecular definition of SOCs. SOCs can be considered as channels that are regulated by STIM1 and require the clustering of STIM1 in response to depletion of the ER Ca2+ stores and its translocation towards the plasma membrane. TRPC1 and other TRPC channels fulfill these criteria. STIM1 binds to TRPC1, TRPC2, TRPC4 and TRPC5 but not to TRPC3, TRPC6 and TRPC7, and STIM1 regulates TRPC1 channel activity. Structure–function analysis reveals that the C-terminus of STIM1 contains the binding and gating function of STIM1. The ERM domain of STIM1 binds to TRPC channels and a lysine-rich region participates in the gating of SOCs and TRPC1. Knock-down of STIM1 by siRNA and prevention of its translocation to the plasma membrane inhibit the activity of native SOCs and TRPC1. These findings support the conclusion that TRPC1 is a SOC. Similar studies with other TRPC channels demonstrate their regulation by STIM1 and indicate that all TRPC channels, except TRPC7, function as SOCs.
Our previous studies have indicated that non-muscle myosin heavy chain IIA (NMMHC IIA) is involved in H
O
-induced neuronal apoptosis, which is associated with the positive feedback loop of ...caspase-3/ROCK1/MLC pathway. However, the neuroprotective effect of NMMHC IIA inhibition with an adeno-associated virus (AAV) vector after transient middle cerebral artery occlusion (MCAO) and its role in caspases-3/ROCK1/MLC pathway remain blurred.
Green fluorescent protein (GFP) and a small hairpin RNA targeting Myh9 (encoding NMMHC IIA) were cloned and packaged into the AAV9 vector. AAV-shMyh9 or control vector were injected into C57BL/6J mice four weeks prior to 60 min MCAO. Twenty-four hours after reperfusion, functional and histological analyses of the mice were performed.
In this study, AAV-shMyh9 was used to down-regulate NMMHC IIA expression in mice. We found that down-regulation of NMMHC IIA could improve neurological scores and histological injury in ischemic mice. Ischemic attack also activated neuronal apoptosis, and this effect was partially attenuated when NMMHC IIA was inhibited by AAV-shMyh9. In addition, AAV-shMyh9 significantly reduced cerebral ischemic/reperfusion (I/R)-induced NMMHC IIA-actin interaction, caspase-3 cleavage, Rho-associated kinase1 (ROCK1) activation and myosin light-chains (MLC) phosphorylation.
Consequently, we showed that AAV-shMyh9 inhibits I/R-induced neuronal apoptosis linked with caspase-3/ROCK1/MLC/NMMHC IIA-actin cascade, which has also been confirmed to be a positive feedback loop. These findings put some insights into the neuroprotective effect of AAV-shMyh9 associated with the regulation of NMMHC IIA-related pathway under ischemic attack and provide a therapeutic strategy for ischemic stroke.
A
bstract
By analyzing 4
.
48 × 10
8
ψ
(3686) events collected with the BESIII detector, we observe the decays
χ
cJ
→
nK
S
0
Λ
¯
+ c
.
c
.
(
J
= 0, 1, 2) for the first time, via the radiative ...transition
ψ
(3686) →
γχ
cJ
. The branching fractions are determined to be (6
.
65 ± 0
.
26
stat
± 0
.
41
syst
) × 10
−
4
, (1
.
66 ± 0
.
12
stat
± 0
.
12
syst
) × 10
−
4
, and (3
.
58 ± 0
.
16
stat
± 0
.
23
syst
) × 10
−
4
for
J
= 0, 1, and 2, respectively.
We report here an extension of the measurement of the all-particle cosmic-ray spectrum with IceTop to lower energy. The new measurement gives full coverage of the knee region of the spectrum and ...reduces the gap in energy between previous IceTop and direct measurements. With a new trigger that selects events in closely spaced detectors in the center of the array, the IceTop energy threshold is lowered by almost an order of magnitude below its previous threshold of 2 PeV. In this paper we explain how the new trigger is implemented, and we describe the new machine-learning method developed to deal with events with very few detectors hit. We compare the results with previous measurements by IceTop and others that overlap at higher energy and with HAWC and Tibet in the 100 TeV range.
Superconductivity was recently observed in CrAs as the helimagnetic order is suppressed by applying pressure, suggesting possible unconventional superconductivity. To reveal the nature of the ...superconducting order parameter of CrAs, here we report the angular dependence of the upper critical field under pressure. Upon rotating the field by 360∘ in the bc plane, six maxima are observed in the upper critical field, where the oscillations have both sixfold- and twofold-symmetric components. Our analysis suggests the presence of an unconventional odd-parity spin-triplet state.
In a superhigh magnetic field, direct Urca reactions can proceed for an arbitrary proton concentration. Since only the electrons with high energy
E
(
E
>
Q
,
Q
is the threshold energy of inverse
β
...-decay) at large Landau levels can be captured, we introduce the Landau level effect coefficient
q
and the effective electron capture rate Γ
eff
. By using Γ
eff
, the values of
L
X
and
L
ν
are calculated, where
L
X
and
L
ν
are the average neutrino luminosity of AXPs and the average X-ray luminosity of AXPs
L
X
, respectively. The complete process of electron capture inside a magnetar is simulated numerically.
Type-II multiferroic materials, in which ferroelectric polarization is induced by inversion nonsymmetric magnetic order, promise new and highly efficient multifunctional applications based on the ...mutual control of magnetic and electric properties. Although this phenomenon has to date been limited to low temperatures, here we report a giant pressure dependence of the multiferroic critical temperature in CuBr_{2}. At 4.5 GPa, T_{C} is enhanced from 73.5 to 162 K, to our knowledge the highest value yet reported for a nonoxide type-II multiferroic. This growth shows no sign of saturating and the dielectric loss remains small under these high pressures. We establish the structure under pressure and demonstrate a 60% increase in the two-magnon Raman energy scale up to 3.6 GPa. First-principles structural and magnetic energy calculations provide a quantitative explanation in terms of dramatically pressure-enhanced interactions between CuBr_{2} chains. These large, pressure-tuned magnetic interactions motivate structural control in cuprous halides as a route to applied high-temperature multiferroicity.
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