62 research outputs found
Tetraquarks, hadronic molecules, meson-meson scattering and disconnected contributions in lattice QCD
There are generally two types of Wick contractions in lattice QCD
calculations of a correlation function --- connected and disconnected ones. The
disconnected contribution is difficult to calculate and noisy, thus it is often
neglected. In the context of studying tetraquarks, hadronic molecules and
meson-meson scattering, we show that whenever there are both connected and
singly disconnected contractions, the singly disconnected part gives the
leading order contribution, and thus should never be neglected. As an explicit
example, we show that information about the scalar mesons sigma, f0(980),
a0(980) and kappa will be lost when neglecting the disconnected contributions.Comment: 9 pages, 2 figure
Lake volume variation in the endorheic basin of the Tibetan Plateau from 1989 to 2019
Lake storage change serves as a unique indicator of natural climate change on the Tibetan Plateau (TP). However, comprehensive lake storage data, especially for lakes smaller than 10 km2, are still lacking in the region. In this dataset, we completed a census of annual relative lake volume (RLV) for 976 lakes, which are larger than 1 km2, on the endorheic basin of the Tibetan Plateau (EBTP) during 1989–2019 using Landsat imagery and digital terrain models. Our method first identifies individual lakes, determines their analysis extents and calculates annual lake area from Landsat imagery. It then derives lake area-elevation relationship, estimates lake surface elevation, and calculates RLV. Validation and comparison with several existing datasets indicate our data are more reliable and comprehensive. Our study complements existing lake datasets by providing a complete and long-term lake water volume change data for the region
Release Profile of Nitrogen during Thermal Treatment of Waste Wooden Packaging Materials
In this paper, the fast pyrolysis experiment of particle board was carried out on a fixed bed reactor and a Py-GC/MS equipment. The effects of temperature and gas phase residence time on the product yields and its components distribution were investigated. The effect of components of particle board on product yields and its components distribution was also investigated. The results showed that the temperature has a great influence on the yields of fast pyrolysis products, and the yield of pyrolysis oil reached the highest at 550°C. The urea-formaldehyde resin would prevent the pyrolysis of particle board. Compared with the bio-oil from fast pyrolysis of wood, the major components of the bio-oil from fast pyrolysis of particle board did not change much
mixing From Lattice QCD
In heavy quark limit, the lowest-lying charmed baryons with two light quarks
can form an SU(3) triplet and sextet. The in the SU(3) triplet and
in the sextet have the same quantum number and can mix due to
the finite charm quark mass and the fact the strange quark is heavier than the
up/down quark. We explore the - mixing by calculating the
two-point correlation functions of the and baryons from
lattice QCD. Based on the lattice data, we adopt two independent methods to
determine the mixing angle between and . After making the
chiral and continuum extrapolation, it is found that the mixing angle
is , which seems insufficient to account for the
large SU(3) symmetry breaking effects found in weak decays of charmed baryons
Effects of Different Freezing Temperatures on the Quality of Rice Dumpling Dough
To investigate the effects of different freezing temperatures on the quality of rice dumpling dough, this paper investigated the effects of freezing at −20, −30, −80, −196 ℃ (liquid nitrogen) on the physicochemical indexes of rice dumpling dough, such as texture characteristics, water loss rate and color. The water distribution and microstructures of rice dumpling dough were studied by NMR, MRI, SEM and other analytical techniques. The results showed that the lower the freezing temperature, the faster the freezing rate. With the decrease of freezing temperature, the water loss rate and light transmittance of rice dumpling dough improved significantly (P0.05) in whiteness, and the magnitude of textural changes was small. The microstructure of the rice dumpling dough was more complete at ultra-low temperature freezing. During the freezing process, the internal water state of the rice dumpling dough was changed, free water and multilayer water were transformed into bound water, liquid water molecules were reduced, and hydrogen proton density was decreased. Combined with the actual situation, the freezing temperature below −30 ℃ could significantly improve the quality of rice dumpling dough
Perioperative management of patients with suspected or confirmed COVID-19:review and recommendations for perioperative management from a retrospective cohort study
Impact of sex and age on respiratory support and length of hospital stay among 1792 patients with COVID-19 in Wuhan, China
Low-energy Scattering of System And the Resonance-like Structure
In this exploratory lattice study, low-energy scattering of the
meson system is analyzed using lattice QCD with
twisted mass fermion configurations with three pion mass values. The
calculation is performed within single-channel L\"uscher's finite-size
formalism. The threshold scattering parameters, namely the scattering length
and the effective range , for the -wave scattering in
channel are extracted. For the cases in our study, the interaction between the
two charmed mesons is weakly repulsive. Our lattice results therefore do not
support the possibility of a shallow bound state for the two mesons for the
pion mass values we studied. This calculation provides some useful information
on the nature of the newly discovered resonance-like structure by
various experimental groups.Comment: 14 pages, 6 figures. Version accepted by PR
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Summary
Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally.
Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies
have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of
the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income
countries globally, and identified factors associated with mortality.
Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to
hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis,
exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a
minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical
status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary
intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause,
in-hospital mortality for all conditions combined and each condition individually, stratified by country income status.
We did a complete case analysis.
Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital
diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal
malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome
countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male.
Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3).
Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income
countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups).
Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome
countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries;
p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients
combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11],
p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20
[1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention
(ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety
checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed
(ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of
parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65
[0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality.
Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome,
middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will
be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger
than 5 years by 2030
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