Abstract
A novel isochronous mass spectrometry, termed as
$$B\rho $$
B
ρ
-defined IMS, has been established at the experimental cooler-storage ring CSRe in Lanzhou. Its potential has been studied ...through high precision mass measurements of
$$^{58}$$
58
Ni projectile fragments. Two time-of-flight detectors were installed in one of the straight sections of CSRe, thus enabling simultaneous measurements of the velocity and the revolution time of each stored short-lived ion. This allows for calculating the magnetic rigidity
$$B\rho $$
B
ρ
and the orbit length
C
of each ion. The accurate
$$B\rho (C)$$
B
ρ
(
C
)
function has been constructed, which is a universal calibration curve used to deduce the masses of the stored nuclides. The sensitivity to single stored ions, fast measurement time, and background-free characteristics of the method are ideally suited to address nuclides with very short lifetimes and smallest production yields. In the limiting case of just a single particle, the achieved mass resolving power allows one to determine its mass-over-charge ratio
m
/
q
with a remarkable precision of merely
$$\sim 5$$
∼
5
keV. Masses of
$$T_z=-3/2$$
T
z
=
-
3
/
2
fp
-shell nuclides are re-determined with high accuracy, and the validity of the isospin multiplet mass equation is tested up to the heaviest isospin quartet with
$$A=55$$
A
=
55
. The new masses are also used to investigate the mirror symmetry of empirical residual proton-neutron interactions.
We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each ...case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos.
The focal plane camera is the core component of the Wide Field-of-view Cherenkov/fluorescence Telescope Array (WFCTA) of the Large High-Altitude Air Shower Observatory (LHAASO). Because of the ...capability of working under moonlight without aging, silicon photomultipliers (SiPM) have been proven to be not only an alternative but also an improvement to conventional photomultiplier tubes (PMT) in this application. Eighteen SiPM-based cameras with square light funnels have been built for WFCTA. The telescopes have collected more than 100 million cosmic ray events and preliminary results indicate that these cameras are capable of working under moonlight. The characteristics of the light funnels and SiPMs pose challenges (e.g. dynamic range, dark count rate, assembly techniques). In this paper, we present the design features, manufacturing techniques and performances of these cameras. Finally, the test facilities, the test methods and results of SiPMs in the cameras are reported here.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Beverloo’s law describes the flow rate of grains discharging from hoppers, where the assumption of a free-fall arch (FFA) is very useful in understanding the physical picture of this process. The FFA ...has been observed in previous experiments but a clear systematic study of the FFA is still necessary. In this paper, dense granular flow in hoppers was studied by numerical simulations, in attempts to explore the free-fall region and its boundary. Generally, the numerical simulation results support the free-fall arch assumption, although the statistical description of the FFA is not exactly equivalent to its strict definition.
•DEM simulation of hopper flows were performed on GPUs.•The free-fall arch structures in hopper flows were plotted by statistical methods.•Spatial profiles in the hopper flows were investigated statistically.•The arch structure is consistent with the profiles but different from ideal FFAs.
The recent success in optical pumping of valley polarization in two-dimensional transition metal dichalcogenides (TMDs) has greatly promoted the concept of valley-based informatics and electronics. ...However, between the demonstrated valley polarization of transient electron-hole pair excitations and practical valleytronic operations, there exist obvious gaps to fill, among which is the valley pump of long-lived charge carriers. Here we discover that the quested valley pump of electrons or holes can be realized simply by scattering at the ubiquitous nonmagnetic disorders, not relying on any specific material property. The mechanism is rooted in the nature of the valley as a momentum space index: the intervalley backscattering in general has a valley contrasted rate due to the distinct momentum transfers, causing a net transfer of population from one valley to another. As examples, we numerically demonstrate the sizable valley pump effects driven by charge current in nanoribbons of monolayer TMDs, where the spin-orbit scattering by nonmagnetic disorders also realizes a spin pump for the spin-valley locked holes. Our finding points to a new opportunity towards valley spintronics, turning disorders from a deleterious factor to a resource of valley and spin polarization.
We previously showed that MYC promoted Burkitt lymphoma (BL) growth by inhibiting the tumor suppressor miR-150, resulting in release of miR-150 targets MYB and ZDHHC11. The ZDHHC11 gene encodes three ...different transcripts including a mRNA (pcZDHHC11), a linear long non-coding RNA (lncZDHHC11) and a circular RNA (circZDHHC11). All transcripts contain the same region with 18 miR-150 binding sites. Here we studied the relevance of circZDHHC11, including this miR-150 binding site region, for growth of BL cells. CircZDHHC11 was mainly present in the cytoplasmic fraction in BL cells and its localization was not altered upon miR-150 overexpression. Knockdown of circZDHHC11 caused a strong inhibition of BL growth without affecting the expression levels of MYC, MYB, miR-150 and other genes. Overexpression of circZDHHC11 neither affected cell growth, nor rescued the phenotype induced by miR-150 overexpression. Genomic deletion of the miR-150 binding site region did not affect growth, nor did it change the effect of circZDHHC11 knockdown. This indicated that the miR-150 binding site region is dispensable for the growth promoting role of circZDHHC11. To conclude, our results show that circZDHHC11 is a crucial factor supporting BL cell growth independent of its ability to sponge miR-150.
Abstract
In laser-driven inertial confinement fusion, driving pressure boosting and smoothing are major challenges. A proposed hybrid-drive (HD) scheme can offer such ideal HD pressure performing ...stable implosion and nonstagnation ignition. Here we report that in the hemispherical and planar ablator targets installed in the semicylindrical hohlraum scaled down from the spherical hohlraum of the designed ignition target, under indirect-drive (ID) laser energies of ~43–50 kJ, the peak radiation temperature of 200 ± 6 eV is achieved. And using only direct-drive (DD) laser energies of 3.6–4.0 kJ at an intensity of 1.8 × 10
15
W/cm
2
, in the hemispherical and planar targets the boosted HD pressures reach 3.8–4.0 and 3.5–3.6 times the radiation ablation pressure respectively. In all the above experiments, significant HD pressure smoothing and the important phenomenon of how a symmetric strong HD shock suppresses the asymmetric ID shock pre-compressed fuel are demonstrated. The backscattering and hot-electron energy fractions both of which are about one-third of that in the DD scheme are also measured.
Aim To determine and compare the diagnostic value of computed tomography (CT)-guided percutaneous core needle biopsy (PCNB) and percutaneous fine-needle aspiration biopsy (PNAB) in pulmonary lesions. ...Materials and methods PubMed, EMBASE, and the Web of Science were systematically searched for relevant studies that investigated the diagnostic accuracy of CT-guided PCNB and/or PNAB for pulmonary lesions up to December 2014. After study selection, data extraction, and quality assessment, the sensitivity (SEN), specificity (SPE), diagnostic odds rate (DOR), positive likelihood ratios (PLR), negative likelihood ratios (NLR), and summary receiver operating characteristic (SROC) curves were calculated using the Meta-Disc 1.4 software. Results Nineteen publications, including 21 independent studies, met the inclusion criteria. Of them, 15 studies were included in the PCNB group and six studies in the PNAB group. The pooled SEN, SPE, DOR, PLR, NLR, and SROC were 0.95, 0.99, 54.72, 0.06, 821.90, and 0.98 in the PCNB group and 0.90, 0.99, 24.71, 0.14, 210.72, and 0.98 in the PNAB group, respectively. Conclusion Based on current evidence, both PCNB and PNAB can be used as diagnostic methods to distinguish benign and malignant pulmonary lesions; the difference between PCNB and PNAB regarding diagnostic accuracy of benign or malignant pulmonary lesions is not obvious.
In this paper, effects of ambient temperature and nanoparticles on surface charge and discharge behavior of epoxy/aluminum nitride (AlN) nanocomposites were investigated. With the rise of ambient ...temperature, the surface discharge strength of epoxy resin decreases and the conductivity shows significant increase. The charges obtain higher energy, their movement becomes more violent and makes it easier for secondary electron emission avalanche. Meanwhile, the specimen’s trap level increases and trap density decreases. 1, 3 and 5 wt% proportions of AlN nanoparticles were added to the epoxy resin to increase the surface discharge strength at different operation temperatures. With the rise of filler content, the trap level, trap density and surface discharge strength increase first and then decrease at 20 °C. The specimen with 5 wt% filler content shows the highest shallow trap density and the one with 1 wt% filler content shows the highest deep trap density at 80 °C. As shallow traps can handle the migration of charges while deep traps may mainly cause electric field distortion, the specimen with 1 wt% filler content shows the highest surface discharge strength at 20 °C while the one with 5 wt% filler content shows the highest at 80 °C. The conclusions can help with finding different formulas to increase epoxy resin’s surface discharge strength at different operation temperatures.
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