3,162 research outputs found
The Pseudoscalar Meson and Heavy Vector Meson Scattering Lengths
We have systematically studied the S-wave pseudoscalar meson and heavy vector
meson scattering lengths to the third order with the chiral perturbation
theory, which will be helpful to reveal their strong interaction. For
comparison, we have presented the numerical results of the scattering lengths
(1) in the framework of the heavy meson chiral perturbation theory and (2) in
the framework of the infrared regularization. The chiral expansion converges
well in some channels.Comment: 10 pages, 1 figures, 4 tables. Corrected typos, Improved numerical
results, and More dicussions. Accepted for publication by Phys.Rev.
A Driving Risk Surrogate and Its Application in Car-Following Scenario at Expressway
Traffic safety is important in reducing death and building a harmonious
society. In addition to studies of accident incidences, the perception of
driving risk is significant in guiding the implementation of appropriate
driving countermeasures. Risk assessment can be conducted in real-time for
traffic safety due to the rapid development of communication technology and
computing capabilities. This paper aims at the problems of difficult
calibration and inconsistent thresholds in the existing risk assessment
methods. It proposes a risk assessment model based on the potential field to
quantify the driving risk of vehicles. Firstly, virtual energy is proposed as
an attribute considering vehicle sizes and velocity. Secondly, the driving risk
surrogate(DRS) is proposed based on potential field theory to describe the risk
degree of vehicles. Risk factors are quantified by establishing submodels,
including an interactive vehicle risk surrogate, a restrictions risk surrogate,
and a speed risk surrogate. To unify the risk threshold, acceleration for
implementation guidance is derived from the risk field strength. Finally, a
naturalistic driving dataset in Nanjing, China, is selected, and 3063 pairs of
following naturalistic trajectories are screened out. Based on that, the
proposed model and other models use for comparisons are calibrated through the
improved particle optimization algorithm. Simulations prove that the proposed
model performs better than other algorithms in risk perception and response,
car-following trajectory, and velocity estimation. In addition, the proposed
model exhibits better car-following ability than existing car-following models
Knowledge networks in science-based start-ups : actors and strategies
The paper investigates the strategic choices made by young science-based firms’ regarding the selection of knowledge sources. Drawing on two streams of research – on alliances and on social networks – two different dimensions of this strategy are considered: the activation of the entrepreneurs’ social capital and the intentional inclusion of new knowledge sources. The data collected for a subset of the Portuguese biotechnology sector are analysed with a view to answer to three research questions: i) To what do extent firms’ rely on entrepreneurs’ personal networks, activating their social capital to access scientific and technological knowledge at start-up; ii) To what extent are new actors added to knowledge networks at start-up; iii) Are there differences between existing and new ties in terms of strength and formalisation. The results obtained confirm the consideration of the strategies underlying network building is vital for an understanding of the configuration of young science-based firms’ knowledge networks. They reveal the existence of different knowledge network building strategies that often combine tie persistence with search for novelty. They also suggest that differences in the network building strategies may be the behind the somewhat contradictory results presented in the literature about the network configuration that is more favourable for innovation
Expanded CURB-65: A new score system predicts severity of community-acquired pneumonia with superior efficiency
Aim of this study was to develop a new simpler and more effective severity score for communityacquired pneumonia (CAP) patients. A total of 1640 consecutive hospitalized CAP patients in Second
Affiliated Hospital of Zhejiang University were included. The effectiveness of different pneumonia
severity scores to predict mortality was compared, and the performance of the new score was validated
on an external cohort of 1164 patients with pneumonia admitted to a teaching hospital in Italy.
Using age≥ 65 years, LDH>230u/L, albumin<3.5g/dL, platelet count<100×109/L, confusion,
urea>7mmol/L, respiratory rate≥30/min, low blood pressure, we assembled a new severity score
named as expanded-CURB-65. The 30-day mortality and length of stay were increased along with
increased risk score. The AUCs in the prediction of 30-day mortality in the main cohort were 0.826
(95%CI, 0.807–0.844), 0.801 (95%CI, 0.781–0.820), 0.756 (95%CI, 0.735–0.777), 0.793 (95%CI,
0.773–0.813) and 0.759 (95%CI, 0.737–0.779) for the expanded-CURB-65, PSI, CURB-65, SMART-COP
and A-DROP, respectively. The performance of this bedside score was confirmed in CAP patients of
the validation cohort although calibration was not successful in patients with health care-associated
pneumonia (HCAP). The expanded CURB-65 is objective, simpler and more accurate scoring system for
evaluation of CAP severity, and the predictive efficiency was better than other score systems
Magnetically-targetable outer-membrane vesicles for sonodynamic eradication of antibiotic-tolerant bacteria in bacterial meningitis
Treatment of acute bacterial meningitis is difficult due to the impermeability of the blood-brain barrier, greatly limiting the antibiotic concentrations that can be achieved in the brain. Escherichia coli grown in presence of iron-oxide magnetic nanoparticles secrete large amounts of magnetic outer-membrane vesicles (OMVs) in order to remove excess Fe from their cytoplasm. OMVs are fully biomimetic nanocarriers, but can be inflammatory. Here, non-inflammatory magnetic OMVs were prepared from an E. coli strain in which the synthesis of inflammatory lipid A acyltransferase was inhibited using CRISPR/Cas9 mediated gene knockout. OMVs were loaded with ceftriaxone (CRO) and meso-tetra-(4-carboxyphenyl)porphine (TCPP) and magnetically driven across the blood-brain barrier for sonodynamic treatment of bacterial meningitis. ROS-generation upon ultrasound application of CRO- and TCPP-loaded OMVs yielded similar ROS-generation as by TCPP in solution. In vitro, ROS-generation by CRO- and TCPP-loaded OMVs upon ultrasound application operated synergistically with CRO to kill a hard-to-kill, CRO-tolerant E. coli strain. In a mouse model of CRO-tolerant E. coli meningitis, CRO- and TCPP-loaded OMVs improved survival rates and clinical behavioral scores of infected mice after magnetic targeting and ultrasound application. Recurrence did not occur for at least two weeks after arresting treatment.</p
Genetic Polymorphism and mRNA Expression Studies Reveal IL6R and LEPR Gene Associations with Reproductive Traits in Chinese Holsteins
Genetic selection of milk yield traits alters the energy distribution of high producing cows, resulting in gene-induced negative energy balance, and consequently, poor body condition scores and reduced reproductive performances. Here, we investigated two metabolic-syndrome pathway genes, IL6R (Interleukin 6 receptor) and LEPR (Leptin receptor), for their polymorphism effects on reproductive performance in dairy cows, by applying polymorphism association analyses in 1588 Chinese Holstein cows (at population level) and gene expression analyses in granulosa cells isolated from eight cows (at cell level). Among the six single nucleotide polymorphisms we examined (two SNPs for IL6R and four SNPs for LEPR), five were significantly associated with at least one reproductive trait, including female fertility traits covering both the ability to recycle after calving and the ability to conceive and keep pregnancy when inseminated properly, as well as calving traits. Notably, the identified variant SNP g.80143337A/C in LEPR is a missense variant. The role of IL6R and LEPR in cattle reproduction were further confirmed by observed differences in relative gene expression levels amongst granulosa cells with different developmental stages. Collectively, the functional validation of IL6R and LEPR performed in this study improved our understanding of cattle reproduction while providing important molecular markers for genetic selection of reproductive traits in high-yielding dairy cattle
In-situ electrical and thermal transport properties of FeySe1-xTex films with ionic liquid gating
We combine in-situ electrical transport and Seebeck coefficient measurements
with the ionic liquid gating technique to investigate superconductivity and the
normal state of FeySe1-xTex (FST) films. We find that the pristine FST films
feature a non-Fermi liquid temperature dependence of the Seebeck coefficient,
i.e., S/T ~ AS lnT, and AS is strongly correlated with the superconducting
transition temperature (Tc). Ionic liquid gating significantly raises Tc of FST
films, for which the Seebeck coefficient displays a novel scaling behavior and
retains the logarithmic temperature dependence. Moreover, a quantitative
relationship between the slope of T-linear resistivity (A\r{ho}) and Tc for
gated films is observed, i.e., (A\r{ho})1/2 ~ Tc, consistent with previous
reports on cuprates and FeSe. The scaling behaviors of AS and A\r{ho} point to
a spin-fluctuation-associated transport mechanism in gated FeySe1-xTex
superconductors.Comment: 12 pages,5 figure
Synthetic Optimization Model and Algorithm for Railway Freight Center Station Location and Wagon Flow Organization Problem
Discovery and identification of potential biomarkers of papillary thyroid carcinoma
<p>Abstract</p> <p>Background</p> <p>Thyroid carcinoma is the most common endocrine malignancy and a common cancer among the malignancies of head and neck. Noninvasive and convenient biomarkers for diagnosis of papillary thyroid carcinoma (PTC) as early as possible remain an urgent need. The aim of this study was to discover and identify potential protein biomarkers for PTC specifically.</p> <p>Methods</p> <p>Two hundred and twenty four (224) serum samples with 108 PTC and 116 controls were randomly divided into a training set and a blind testing set. Serum proteomic profiles were analyzed using SELDI-TOF-MS. Candidate biomarkers were purified by HPLC, identified by LC-MS/MS and validated using ProteinChip immunoassays.</p> <p>Results</p> <p>A total of 3 peaks (<it>m/z </it>with 9190, 6631 and 8697 Da) were screened out by support vector machine (SVM) to construct the classification model with high discriminatory power in the training set. The sensitivity and specificity of the model were 95.15% and 93.97% respectively in the blind testing set. The candidate biomarker with <it>m/z </it>of 9190 Da was found to be up-regulated in PTC patients, and was identified as haptoglobin alpha-1 chain. Another two candidate biomarkers (6631, 8697 Da) were found down-regulated in PTC and identified as apolipoprotein C-I and apolipoprotein C-III, respectively. In addition, the level of haptoglobin alpha-1 chain (9190 Da) progressively increased with the clinical stage I, II, III and IV, and the expression of apolipoprotein C-I and apolipoprotein C-III (6631, 8697 Da) gradually decreased in higher stages.</p> <p>Conclusion</p> <p>We have identified a set of biomarkers that could discriminate PTC from non-cancer controls. An efficient strategy, including SELDI-TOF-MS analysis, HPLC purification, MALDI-TOF-MS trace and LC-MS/MS identification, has been proved successful.</p
- …