1,508 research outputs found
Symmetries of SU(2) Skyrmion in Hamiltonian and Lagrangian approaches
We apply the Batalin-Fradkin-Tyutin (BFT) method to the SU(2) Skyrmion to
study the full symmetry structure of the model at the first class Hamiltonian
level. On the other hand, we also analyze the symmetry structure of the action
having the WZ term, which corresponds to this Hamiltonian, in the framework of
the Lagrangian approach. Furthermore, following the BFV formalism we derive the
BRST invariant gauge fixed Lagrangian from the above extended action.Comment: 14 pages, final revised version, to appear in Mod. Phys. Lett.
Pattern Formation in a Two-Dimensional Array of Oscillators with Phase-Shifted Coupling
We investigate the dynamics of a two-dimensional array of oscillators with
phase-shifted coupling. Each oscillator is allowed to interact with its
neighbors within a finite radius. The system exhibits various patterns
including squarelike pinwheels, (anti)spirals with phase-randomized cores, and
antiferro patterns embedded in (anti)spirals. We consider the symmetry
properties of the system to explain the observed behaviors, and estimate the
wavelengths of the patterns by linear analysis. Finally, we point out the
implications of our work for biological neural networks
model with Hopf term and fractional spin statistics
We reconsider the model with the Hopf term by using the
Batalin-Fradkin-Tyutin (BFT) scheme, which is an improved version of the Dirac
quantization method. We also perform a semi-classical quantization of the
topological charge Q sector by exploiting the collective coordinates to
explicitly show the fractional spin statistics.Comment: 15 page
Symplectic embedding and Hamilton-Jacobi analysis of Proca model
Following the symplectic approach we show how to embed the Abelian Proca
model into a first-class system by extending the configuration space to include
an additional pair of scalar fields, and compare it with the improved Dirac
scheme. We obtain in this way the desired Wess-Zumino and gauge fixing terms of
BRST invariant Lagrangian. Furthermore, the integrability properties of the
second-class system described by the Abelian Proca model are investigated using
the Hamilton-Jacobi formalism, where we construct the closed Lie algebra by
introducing operators associated with the generalized Poisson brackets.Comment: 24 page
Appropriate number of observations for determining hand hygiene compliance among healthcare workers
Abstract
We sought to determine the minimum number of observations needed to determine hand hygiene (HH) compliance among healthcare workers. The study was conducted at a referral hospital in South Korea. We retrospectively analyzed the result of HH monitoring from January to December 2018. HH compliance was calculated by dividing the number of observed HH actions by the total number of opportunities. Optimal HH compliance rates were calculated based on adherence to the six-step technique recommended by the World Health Organization. The minimum number of required observations (n) was calculated by the following equation using overall mean value (ρ), absolute precision (d), and confidence interval (CI) (1 − α) [the equation:
n
≥
Z
α
/
2
2
×
ρ
×
1
-
ρ
/
d
2
]. We considered ds of 5%, 10%, 20%, and 30%, with CIs of 99%, 95%, and 90%. During the study period, 8791 HH opportunities among 1168 healthcare workers were monitored. Mean HH compliance and optimal HH compliance rates were 80.3% and 59.7%, respectively. The minimum number of observations required to determine HH compliance rates ranged from 2 (
d
: 30%, CI: 90%) to 624 (
d
: 5%, CI: 99%), and that for optimal HH compliance ranged from 5 (
d
: 30%, CI: 90%) to 642 (
d
: 5%, CI: 99%). Therefore, we found that our hospital required at least five observations to determine optimal HH compliance
Targeted gene suppression through double-stranded RNA application using easy-to-use methods in Arabidopsis thaliana
Abstract
RNA interference (RNAi) is an RNA-dependent gene silencing process that is regulated by the interaction between the RNA-induced silencing complex (RISC) and double-stranded RNA (dsRNA). Exogenous dsRNAs are imported directly into the cytoplasm, where they are cleaved by Dicer into short dsRNA fragments of 20–25 base pairs. These short dsRNA fragments, called small interfering RNAs (siRNAs) have sequence-specific interaction with target genes. The guide strand, onto which siRNAs are incorporated in the RISC interacts with the target mRNA sequence, thereby inducing cleavage and degradation of target messenger RNAs (mRNAs) by ribonucleases. Recent studies have shown that plant dsRNA treatments can induce RNAi. However, the dsRNA application methods and delivery systems involved have not been well examined. In this study, dsRNA was introduced to Arabidopsis thaliana by two methods: dipping and spray. We synthesized two dsRNAs designed to target mRNAs encoding enhanced green fluorescent protein (EGFP). After applying dsRNAs that target EGFP, we found an obvious reduction in GFP expression. This was determined using fluorescence microscopy and quantitative reverse transcription PCR to assess the mRNA levels of the auxin-sensitive reporter DR5-EGFP Arabidopsis thaliana. Our data revealed that applying target gene-specific exogenous dsRNAs can induce suppression of target genes of interest whether the dipping or spray method is used. This study therefore provides a foundation for understanding how to apply and deliver dsRNAs in plants
Visualization of a mammalian mitochondrion by coherent x-ray diffractive imaging
We report a three dimensional (3D) quantitative visualization of a mammalian mitochondrion by coherent x-ray diffractive imaging (CXDI) using synchrotron radiation. The internal structures of a mitochondrion from a mouse embryonic fibroblast cell line (NIH3T3) were visualized by tomographic imaging at approximately 60 nm resolution without the need for sectioning or staining. The overall structure consisted of a high electron density region, composed of the outer and inner membranes and the cristae cluster, which enclosed the lower density mitochondrial matrix. The average mass density of the mitochondrion was about 1.36 g/cm3. Sectioned images of the cristae reveal that they have neither a baffle nor septa shape but were instead irregular. In addition, a high resolution, about 14 nm, 2D projection image was captured of a similar mitochondrion with the aid of strongly scattering Au reference objects. Obtaining 3D images at this improved resolution will allow CXDI to be an effective and nondestructive method for investigating the innate structure of mitochondria and other important life supporting organelles. ? 2017 The Author(s).11Ysciescopu
Comparison of the kinematics, repeatability, and reproducibility of five different multi-segment foot models
Abstract
Background
Multi-segment foot models (MFMs) for assessing three-dimensional segmental foot motions are calculated via various analytical methods. Although validation studies have already been conducted, we cannot compare their results because the experimental environments in previous studies were different from each other. This study aims to compare the kinematics, repeatability, and reproducibility of five MFMs in the same experimental conditions.
Methods
Eleven healthy males with a mean age of 26.5 years participated in this study. We created a merged 29-marker set including five MFMs: Oxford (OFM), modified Rizzoli (mRFM), DuPont (DFM), Milwaukee (MiFM), and modified Shriners Hospital for Children Greenville (mSHCG). Two operators applied the merged model to participants twice, and then we analysed two relative angles of three segments: shank-hindfoot (HF) and hindfoot-forefoot (FF). Coefficients of multiple correlation (CMC) and mean standard errors were used to assess repeatability and reproducibility, and statistical parametric mapping (SPM) of the t-value was employed to compare kinematics.
Results
HF varus/valgus of the MiFM and mSHCG models, which rotated the segment according to radiographic or goniometric measurements during the reference frame construction, were significantly more repeatable and reproducible, compared to other models. They showed significantly more dorsiflexed HF and plantarflexed FF due to their static offset angles. DFM and mSHCG showed a greater range of motion (ROM), and some models had significantly different FF points of peak angle.
Conclusions
Under the same conditions, rotating the segment according to the appropriate offset angle obtained from radiographic or goniometric measurement increased reliability, but all MFMs had clinically acceptable reliability compared to previous studies. Moreover, in some models, especially HF varus/valgus, there were differences in ROM and points of peak angle even with no statistical difference in SPM curves. Therefore, based on the results of this study, clinicians and researchers involved in the evaluation of foot and ankle dysfunction need an understanding of the specific features of each MFM to make accurate decisions
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