419 research outputs found
RF-thermal-structural-RF coupled analysis on the travelling wave disk-loaded accelerating structure
Travelling wave (TW) disk-loaded accelerating structure is one of the key
components in normal conducting (NC) linear accelerators, and has been studied
for many years. In the design process, usually after the dimensions of each
cell and the two couplers are finalized, the structure is fabricated and tuned,
and then the whole structure characteristics can be measured by the vector
network analyzer. Before the structure fabrication, the whole structure
characteristics are less simulated limited by the available computer
capability. In this paper, we described the method to do the
RF-thermal-structural-RF coupled analysis on the TW disk-loaded structure with
one single PC. In order to validate our method, we first analyzed and compared
our RF simulation results on the 3m long BEPCII structure with the
corresponding experimental results, which shows very good consistency. Finally,
the RF-thermal-structure-RF coupled analysis results on the 1.35m long NSC KIPT
linac accelerating structure are presented.Comment: 5 pages, 16 figures, Submitted to the Chinese Physics C (Formerly
High Energy Physics and Nuclear Physics
Prenatal Diagnosis of Pulmonary Sequestration by Ultrasound and Magnetic Resonance Imaging
A 36-year-old multigravida, G2P1, underwent routine ultrasound scan at 22+1 weeks of gestation, which revealed a single normally growing fetus with left intrathoracic mass and left displacement of the cardiac apex. The left intrathoracic wedge-shaped hyperechogenic mass, measuring 32 Ă— 25 mm in size, was situated at the lower portion of the left lung. A combination of color and power Doppler ultrasound allowed visualization of a vessel arising from the descending aorta, which supplied the mass. The diagnosis of extralobar pulmonary sequestration was made. Magnetic resonance imaging (MRI) was also performed and revealed a well-defined mass with homogeneous high-signal intensity when compared with normal lung tissue in the left upper lung field, which was compatible with pulmonary sequestration. The pulmonary mass was followed up by color and power Doppler every 2 weeks. The peak velocity of 11.85 cm/sec and the diameter of the feeding artery of 1.19 mm gradually decreased and disappeared 8 weeks later. The intrathoracic mass disappeared 10 weeks later at 32+1 gestational weeks. Repeat MRI also revealed spontaneous regression of the mass in favor of resorption of sequestration. The fetus was delivered at 38+1 gestational weeks. A male newborn weighing 2,520 g was spontaneously delivered with an Apgar score of 8 at 1 minute and 9 at 5 minutes. In our patient, it is suggested that progressive decreases in the peak velocity of the feeding vessel heralded the spontaneous regression of pulmonary sequestration not associated with hydrops/hydrothorax
Metal-bonded perovskite lead hydride with phonon-mediated superconductivity up to 46 K under atmospheric pressure
In the search for high-temperature superconductivity in hydrides, a plethora
of multi-hydrogen superconductors have been theoretically predicted, and some
have been synthesized experimentally under ultrahigh pressures of several
hundred GPa. However, the impracticality of these high-pressure methods has
been a persistent issue. In response, we propose a new approach to achieve
high-temperature superconductivity under atmospheric pressure by implanting
hydrogen into lead to create a stable few-hydrogen metal-bonded perovskite,
PbH. This approach diverges from the popular design methodology of
multi-hydrogen covalent high critical temperature () superconductors under
ultrahigh pressure. By solving the anisotropic Migdal-Eliashberg (ME)
equations, we demonstrate that perovskite PbH is a typical phonon-mediated
superconductor with a of 46 K, which is six times higher than that of
bulk Pb (7.22 K) and higher than that of MgB (39 K). The high can be
attributed to the strong electron-phonon coupling (EPC) strength of 2.45, which
arises from hydrogen implantation in lead that induces several high-frequency
optical phonon modes with a relatively large phonon linewidth resulting from H
atom vibration. The metallic-bonding in perovskite PbH not only improves
the structural stability but also guarantees better ductility than the widely
investigated multi-hydrogen, iron-based, and cuprate superconductors. These
results suggest that there is potential for the exploration of new
high-temperature superconductors under atmospheric pressure and may reignite
interest in their experimental synthesis soon.Comment: 6 pages, 4 figure
Associations of personal care products use with reproductive outcomes of IVF/ICSI treatment
IntroductionPersonal care products (PCPs) contain a number of endocrine-disrupting chemicals (EDCs) that could potentially affect the reproductive function in women of childbearing age. However, studies focused on the effects of PCPs use on reproductive outcomes are very limited. The current study aimed to explore the relationships between PCPs use patterns and reproductive outcomes in women undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment.MethodsA total of 1500 women from the Tongji Reproductive and Environmental (TREE) study between December 2018 and January 2020 were included in this study. Participants provided characteristics of PCPs use within the previous three months. Retrieved oocyte number, mature oocyte number, two distinct pronuclei (2PN) zygote number, fertilization rate, cleavage rate, blastocyst formation rate, implantation, clinical pregnancy, miscarriage, and live birth were followed up as reproductive endpoints. Generalized linear regression model was utilized to assess the associations between various categories of PCPs use and reproductive endpoints of IVF/ICSI.ResultsAfter adjusting for relevant covariates, women who used skin care products ≥14 times per week had a reduction of 22.4% in the maturation rate (95% CI: -39.2%, -1.6%) compared to participants who did not use skin care products. After transferring fresh embryos, women who used cosmetics 1–2 times per week (adjusted OR = 2.2, 95% CI: 1.0, 4.8) or 3–7 times per week (adjusted OR = 2.5, 95% CI: 1.2, 5.2) had a higher possibility of miscarriage than those who did not use cosmetics. There was negative association between the use of gel or soap and the cleavage rate among women aged < 30 years old (P for interaction = 0.01). Among women with BMI ≥ 24 kg/m2, the use of gel or soap was negatively associated with the blastocyst formation rate (P for interaction = 0.04), while cosmetics use was negatively associated with the maturation rate (P for interaction = 0.001).ConclusionOur findings suggest that the use of PCPs in women of reproductive age have a potential adverse impact on IVF/ICSI outcomes, particularly skin care and cosmetic products
Comparison of bacterial communities of conventional and A-stage activated sludge systems
The bacterial community structure of 10 different wastewater treatment systems and their influents
has been investigated through pyrosequencing, yielding a total of 283486 reads. These bioreactors
had different technological configurations: conventional activated sludge (CAS) systems and very
highly loaded A-stage systems. A-stage processes are proposed as the first step in an energy producing
municipal wastewater treatment process. Pyrosequencing analysis indicated that bacterial community
structure of all influents was similar. Also the bacterial community of all CAS bioreactors was similar.
Bacterial community structure of A-stage bioreactors showed a more case-specific pattern. A core
of genera was consistently found for all influents, all CAS bioreactors and all A-stage bioreactors,
respectively, showing that different geographical locations in The Netherlands and Spain did not affect
the functional bacterial communities in these technologies. The ecological roles of these bacteria
were discussed. Influents and A-stage bioreactors shared several core genera, while none of these
were shared with CAS bioreactors communities. This difference is thought to reside in the different
operational conditions of the two technologies. This study shows that bacterial community structure of
CAS and A-stage bioreactors are mostly driven by solids retention time (SRT) and hydraulic retention
time (HRT), as suggested by multivariate redundancy analysis.Department of Civil EngineeringInstitute of Water Research from the University of GranadaDepartment of Environmental Biotechnology of the Delft University of Technolog
Spatio-temporal divergence in the responses of Finland's boreal forests to climate variables
Spring greening in boreal forest ecosystems has been widely linked to increasing temperature, but few studies have attempted to unravel the relative effects of climate variables such as maximum temperature (TMX), minimum temperature (TMN), mean temperature (TMP), precipitation (PRE) and radiation (RAD) on vegetation growth at different stages of growing season. However, clarifying these effects is fundamental to better understand the relationship between vegetation and climate change. This study investigated spatio-temporal divergence in the responses of Finland's boreal forests to climate variables using the plant phenology index (PPI) calculated based on the latest Collection V006 MODIS BRDF-corrected surface reflectance products (MCD43C4) from 2002 to 2018, and identified the dominant climate variables controlling vegetation change during the growing season (May-September) on a monthly basis. Partial least squares (PLS) regression was used to quantify the response of PPI to climate variables and distinguish the separate impacts of different variables. The study results show the dominant effects of temperature on the PPI in May and June, with TMX, TMN and TMP being the most important explanatory variables for the variation of PPI depending on the location, respectively. Meanwhile, drought had an unexpectedly positive impact on vegetation in few areas. More than 50 % of the variation of PPI could be explained by climate variables for 68.5 % of the entire forest area in May and 87.7 % in June, respectively. During July to September, the PPI variance explained by climate and corresponding spatial extent rapidly decreased. Nevertheless, the RAD was found be the most important explanatory variable to July PPI in some areas. In contrast, the PPI in August and September was insensitive to climate in almost all of the regions studied. Our study gives useful insights on quantifying and identifying the relative importance of climate variables to boreal forest, which can be used to predict the possible response of forest under future warming.Peer reviewe
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