2,825 research outputs found
Dirac-boson stars
In this paper, we construct \textit{Dirac-boson stars} (DBSs) model composed
of a scalar field and two Dirac fields. The scalar field and both Dirac fields
are in the ground state. We consider the solution families of the DBSs for the
synchronized frequency and the nonsynchronized frequency
cases, respectively. We find several different solutions
when the Dirac mass and scalar field frequency
are taken in some particular ranges. In contrast, no similar
case has been found in previous studies of multistate boson stars. Moreover, we
discuss the characteristics of each type of solution family of the DBSs and
present the relationship between the ADM mass of the DBSs and the
synchronized frequency or the nonsynchronized frequency
. Finally, we calculate the binding energy of the DBSs
and investigate the relationship of with the synchronized frequency
or the nonsynchronized frequency .Comment: 26 pages, 12 figure
Excited Dirac stars with higher azimuthal harmonic index
In this paper, we investigate the properties of the first excited state Dirac
stars (DSs) with higher azimuthal harmonic index (specifically, the azimuthal
harmonic indexes = , , ), as well as the relationship
between the ADM mass and angular momentum of Dirac stars with respect to
frequency. Moreover, We find that the ergospheres of DSs appear at lower spinor
field frequencies, and both the ergospheres and the distribution of the spinor
field functions are asymmetric about the equatorial plane. Furthermore, we
introduce the ground state scalar field and examine its impact on this system,
which is known as the multi-state Dirac-boson stars (DBSs) model. We show
various types of solution families for DBSs under both synchronized frequency
and nonsynchronized frequencies and find that similar to DSs, the
spinor field and the ergospheres of DBSs are also asymmetric about the
equatorial plane, but the ergospheres appear at higher spinor field
frequencies.Comment: 22 pages, 8 figure
Tribological properties of surface dimple-textured by pellet-pressing
AbstractSurface texturing is thought to be as an effective tribological method of decreasing friction coefficient of contact pairs. Firstly, AISI1045 steel surface is dimple-textured by a convenient and economical way of pellet-pressing, then, the textured and polished samples is against SiC ball lubricated by engine oil to carry out tribological tests in reciprocating mode in tribomachine type UMT-II. It is concluded that surface dimple-texture made by pellet-pressing is beneficial to improve tribological properties lubricated by engine oil under10N load and 5mm/s sliding speed
The Experiment Research of the MoS 2
This paper investigated the theory of the friction sliding isolation structure, The MoS2 solid lubricant was adopted as isolation bearing friction materials, A new sliding isolation bearing was designed and made. The formula of the friction factor and the compression stress was proposed
Mediastinal Lymph Node Metastases in Thyroid Cancer: Characteristics, Predictive Factors, and Prognosis
Background. Mediastinal lymph node metastases (MLNM) have not been extensively studied. The aim of this study is to investigate the characteristics, predictive factors, and prognosis of MLNM in thyroid cancer. Methods. This is a retrospective study based on the thyroid cancer patients with MLNM at our institution from 2008 to 2015. Results. In total, 73 thyroid cancer patients with positive MLNM were included in this study. It contained sixty patients (82.2%) with papillary thyroid carcinoma (PTC), twelve (16.4%) with medullary thyroid carcinoma, and one (1.4%) with anaplastic thyroid carcinoma. Forty-eight patients had the surgery as initial treatment. Fifty-three (72.6%) patients remained disease-free, and fifteen (20.5%) developed a regional recurrence. Distant metastases occurred in four (5.5%) patients and five (6.8%) patients died. Five-year overall survival rate and disease-free survival (DFS) rate of the PTC patients for initial treatment are 95.4% and 77.2%, respectively. Extrathyroidal extension and multiple lymph nodes involved were associated with DFS in PTC patients. Conclusions. Initial therapeutic control is very important for the thyroid cancer patients. Extrathyroidal extension and multiple mediastinal lymph nodes involved were the influence factors of prognosis in the thyroid cancer patients with MLNM
Comparison of the Therapeutic Effects of Acupuncture at PC6 and ST36 for Chronic Myocardial Ischemia
We aimed to compare the differences of the effects on chronic myocardial ischemia (MI) of acupuncture at PC6 and ST36. The chronic MI model of minipigs was created by implanting an Ameroid constrictor on the left anterior descending coronary artery (LAD) and then two weeks’ acupuncture was stimulated at PC6 or ST36, respectively. The results showed that both acupoints’ stimulation decreased the serous cardiac troponin T (cTnT) and ischemia modified albumin (IMA) significantly and improved the ischemic ECG changes. The amplitude of pathological Q wave in the PC6 group decreased more significantly than that of the ST36 group. The cardiovascular magnetic resonance imaging (cMRI) results showed that the decreased left ventricular ejection fraction (LVEF) was not improved obviously in both groups. The left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) enlarged progressively even after acupuncture. The left ventricular wall mass (LVWM) in the ST36 group increased more obviously than that of the PC6 group, which paralleled the decreasing angiotensin II (Ang II) concentration in the plasma. These results suggested that acupuncture at PC6 or ST36 was effective for protecting the myocardium from chronic ischemic injury, and the effect of PC6 seemed to be better
Clinical and Epidemiologic Research Does Cigarette Smoking Alter the Risk of Pterygium? A Systematic Review and Meta-Analysis
PURPOSE. To determine the association of cigarette smoking with pterygium. METHODS. Potentially eligible studies published from the year 1946 to December 28, 2013 were identified from MEDLINE, EMBASE, and Cochrane Library databases, and reference lists. All studies that evaluated smoking as an independent factor for pterygium were identified. Study-specific odds ratios (ORs) were combined using the random-effects model when P < 0.1 in the test for heterogeneity, or otherwise the fixed-effects model was used. Metaregression, sensitivity analysis, and evaluation of potential biases were undertaken. The ORs with 95% confidence intervals (CIs) of smoking as an associated factor for pterygium were analyzed. RESULTS. We included 24 articles incorporating 95,279 participants from 20 cross-sectional studies, 2 hospital-based case-control studies, and 2 population-based cohort studies. The combined OR of cigarette smoking (current or ever smoked) for risk of pterygium was 0.82 (95% CI, 0.69-0.97; P ¼ 0.025). The results remained consistent among current smokers (OR, 0.68; 95% CI, 0.61-0.76; P ¼ 4.57 3 10 À12 ), but not in ex-smokers (OR, 1.05; 95% CI, 0.87-1.27; P ¼ 0.59). The impact of ultraviolet light (UV) exposure (P ¼ 0.082) and sex (P ¼ 0.553) on the effect of smoking was insignificant in meta-regression. Sensitivity analysis confirmed the protective effect and nonrelevance of these two study-level variables. Begg's funnel plots and Egger's test showed minimal publication bias. CONCLUSIONS. The results of this meta-analysis show that cigarette smoking was associated with a reduced risk of pterygium, especially in current smokers. This effect may be independent of UV exposure and sex. Investigations are needed to unveil its molecular basis serving therapeutic purposes. Keywords: smoking, cigarette smoking, pterygium, pterygia, risk factor, protective factor P terygium is an inflammatory fibrovascular mass that extends from the interpalpebral conjunctiva over the adjacent peripheral cornea. 1 Its corneal ingrowth can lead to ocular irritation and visual impairment by induction of astigmatism, blockade of visual axis, or loss of corneal transparency. 3-24 Cigarette smoking, a modifiable factor and an important public health problem, has been studied as a risk factor for pterygium. METHODS Eligibility Criteria We included studies that fulfilled the following criteria: (1) a cross-sectional, prospective cohort, or case-control study; (2) diagnosis of pterygium was based on slit-lamp examination by ophthalmologists; (3) smoking status was recorded and tested as an independent factor; (4) adjusted odds ratio (OR) and 95% confidence interval (95% CI) were estimated with multiple logistic regression; or the occurrence of pterygium in subjects with and without current/past smoking history were reported or can be resolved. Animal studies, case reports, reviews, abstracts, conference proceedings, editorials, non-English articles, and studies that did not analyze smoking as a factor were excluded
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