5,723 research outputs found
Fermion masses in the economical 3-3-1 model
We show that, in frameworks of the economical 3-3-1 model, all fermions get
masses. At the tree level, one up-quark and two down-quarks are massless, but
the one-loop corrections give all quarks the consistent masses. This conclusion
is in contradiction to the previous analysis in which, the third scalar triplet
has been introduced. This result is based on the key properties of the model:
First, there are three quite different scales of vacuum expectation values:
\om \sim {\cal O}(1) \mathrm{TeV}, v \approx 246 \mathrm{GeV} and . Second, there exist two types of Yukawa couplings
with different strengths: the lepton-number conserving couplings 's and the
lepton-number violating ones 's satisfying the condition in which the second
are much smaller than the first ones: .
With the acceptable set of parameters, numerical evaluation shows that in
this model, masses of the exotic quarks also have different scales, namely, the
exotic quark () gains mass GeV, while the
D_\al exotic quarks (q_{D_\al} = -1/3) have masses in the TeV scale:
m_{D_\al} \in 10 \div 80 TeV.Comment: 20 pages, 8 figure
Neutrino masses in the economical 3-3-1 model
We show that, in frameworks of the economical 3-3-1 model, the suitable
pattern of neutrino masses arises from the three quite different sources - the
lepton-number conserving, the spontaneous lepton-number breaking and the
explicit lepton-number violating, widely ranging over the mass scales including
the GUT one: , , \om\sim
O(1) \mathrm{TeV} and . At
the tree-level, the model contains three Dirac neutrinos: one massless, two
large with degenerate masses in the order of the electron mass. At the one-loop
level, the left-handed and right-handed neutrinos obtain Majorana masses
in orders of and degenerate in
, while the Dirac masses get a large reduction down to
scale through a finite mass renormalization. In this model, the contributions
of new physics are strongly signified, the degenerations in the masses and the
last hierarchy between the Majorana and Dirac masses can be completely removed
by heavy particles. All the neutrinos get mass and can fit the data.Comment: 15 pages, 8 figure
Geometric effects on mixing performance in a novel passive micromixer with trapezoidal-zigzag channels
A novel passive micromixer, called a trapezoidal-zigzag micromixer (TZM), is reported. A TZM is composed of trapezoidal channels in a zigzag and split–recombine arrangement that enables multiple mixing mechanisms, including splitting–recombining, twisting, transversal flows, vortices, and chaotic advection. The effects of geometric parameters of the TZM on mixing performance are systematically investigated by the Taguchi method and numerical simulations in COMSOL Multiphysics. The number of mixing units, the slope angle of the trapezoidal channel, the height of the constriction element, and the width ratio between the middle-trapezoidal channel and the side-trapezoidal channel are the four parameters under study. The mixing performance of the TZM is investigated at three different Reynolds number (Re) values of 0.5, 5, and 50. The results showed that a TZM with six mixing units, a trapezoidal slope angle of 75°, a constricting height of 100 µm, and a width ratio of 0.5 has the highest mixing efficiency. This optimal TZM has a mixing efficiency greater than 85% for Re values from 0.1 to 80. In particular, for Re  ≤  0.9 and Re  ≥  20, the mixing efficiency of the optimal TZM is greater than 90%. The proposed TZM has a higher mixing efficiency and a smaller footprint than previously reported micromixers
Modeling the Combined Effects of River Stage and Groundwater Flow on Riverbank Stability Before and After Dam Removal
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive
Assessment of Dam Removal in Dajia River Basin with Numerical Modeling
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive
Factors affecting the decision to choose a university of high school students: A study in An Giang Province, Vietnam
It is important to provide high school students with the necessary information for them to consult and make a decision to choose a university. The study aims to identify and evaluate the influence of factors in the decision to choose a university for high school students. The questionnaire survey method was used to collect data from 393 students from eight high schools in An Giang Province, Vietnam. Exploratory factor analysis and linear regression were used to analyze the data. The research results show that students are quite satisfied and quite certain with their decision to choose a university, while there are six important factors affecting the decision to choose a university. Influential factors with decreasing order of magnitude are: i) Factors consulted by teachers, family, friends, and relatives; ii) Factors of future job opportunities; iii) Factors of media activities; iv) Factors of learning conditions; v) Factors of university reputation; vi) Factors belong to the students themselves. The findings of the study show that there is no statistically significant difference between the group of males and females, between grades 10, 11, and 12. Besides, there is a statistically significant difference between students in high schools. The findings of this study have theoretical and practical implications for university admissions in Vietnam. Proposals made to university administrators were discussed. From the research results, we want to help students find the right university, and support universities to improve the efficiency of admissions
Exploring the heterogeneity of effects of corticosteroids on acute respiratory distress syndrome: a systematic review and meta-analysis
INTRODUCTION: The effectiveness of corticosteroid therapy on the mortality of acute respiratory distress syndrome (ARDS) remains under debate. We aimed to explore the grounds for the inconsistent results in previous studies and update the evidence. METHODS: We searched MEDLINE, Cochrane Central Register of Controlled Trials and Web of Science up to December 2013. Eligible studies included randomized clinical trials (RCTs) and cohort studies that reported mortality and that had corticosteroid nonusers for comparison. The effect of corticosteroids on ARDS mortality was assessed by relative risk (RR) and risk difference (RD) for ICU, hospital, and 60-day mortality using a random-effects model. RESULTS: Eight RCTs and 10 cohort studies were included for analysis. In RCTs, corticosteroids had a possible but statistically insignificant effect on ICU mortality (RD, −0.28; 95% confidence interval (CI), −0.53 to −0.03 and RR, 0.55; 95% CI, 0.24 to 1.25) but no effect on 60-day mortality (RD, −0.01; 95% CI, −0.12 to 0.10 and RR, 0.97; 95% CI, 0.75 to 1.26). In cohort studies, corticosteroids had no effect on ICU mortality (RR, 1.05; 95% CI, 0.74 to 1.49) but non-significantly increased 60-day mortality (RR, 1.30; 95% CI, 0.96 to 1.78). In the subgroup analysis by ARDS etiology, corticosteroids significantly increased mortality in influenza-related ARDS (three cohort studies, RR, 2.45, 95% CI, 1.40 to 4.27). CONCLUSIONS: The effects of corticosteroids on the mortality of ARDS differed by duration of outcome measures and etiologies. Corticosteroids did not improve longer-term outcomes and may cause harm in certain subgroups. Current data do not support routine use of corticosteroids in ARDS. More clinical trials are needed to specify the favorable and unfavorable subgroups for corticosteroid therapy
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Design and simulation of superconducting Lorentz Force Electrical Impedance Tomography (LFEIT)
Study of Critical Current and n-Values of 2G HTS Tapes: Their Magnetic Field-Angular Dependence
Since many applications of YBCO tapes operate in external magnetic fields, it is necessary to investigate the magneto-angular dependence of critical current and n-values in coated conductors. In this paper, five commercial YBCO tapes with different microstructures produced by three different manufacturers are chosen. The selected samples have width of 2.0, 4.0, 4.8, 6.0 or 12mm, with copper, brass or stainless steel laminations. The critical current density dependence Jc (B,θ) and n-values characteristics n(B,θ) of the tapes are comprehensively measured under various magnetic fields and orientations. Afterwards, the obtained experimental data sets are successfully fitted using a novel multi-objective model which considers the material anisotropy. By using this approach a fitting function Ic (B,θ) can always be obtained to accurately describe the experimental data, regardless of the fabrication and width differences of the superconducting tapes. Moreover, our experiment shows that when subject to different external magnetic fields, the angular dependence of n-values characteristics are directly correlated with the corresponding critical current profiles. Our results are helpful to predict the critical current of electromagnetically interacting 2G HTS wires and thereby improving the design and performance of the devices made from YBCO tapes
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