Nucleon Electromagnetic Form Factors in QCD

The nucleon electromagnetic form factors are calculated in light cone QCD sum rules framework using the most general form of the nucleon interpolating current. Using two forms of the distribution amplitudes (DA's), predictions for the form factors are presented and compared with existing experimental data. It is shown that our results describe remarkably well the existing experimental data.Comment: 21 pages, 7 figure

"Massless'' Spin-32\frac{3}{2} Fields in the de Sitter Space

In this paper, the ``massless" spin-$\frac{3}{2}$ fields in the de Sitter space are considered. This work is in the continuation of a previous paper devoted to the quantization of the de Sitter ``massive" spin-$\frac{3}{2}$ fields. Due to the appearance of gauge invariance and indefinite metric, the covariant quantization of the ``massless" spin-$\frac{3}{2}$ fields requires an indecomposable representation of the de Sitter group. The gauge fixing corresponding to the simplest Gupta-Bleuler structure is used, and gauge invariant field is discussed. The field equation is obtained by using the Casimir operator of the de Sitter group. The solutions are written in terms of the coordinate-independent de Sitter plane waves. Finally, the generalized two-point function is calculated.Comment: 18 pages, no figure, submitted in E. Phys. J. C. arXiv admin note: text overlap with arXiv:gr-qc/0608004 by other author

Vasopressin attenuates ischemia-reperfusion injury via reduction of oxidative stress and inhibition of mitochondrial permeability transition pore opening in rat hearts

Aim of this study was to investigate the involvement of the mitochondrial permeability transition pore (MPTP) and oxidative stress in the cardioprotective effect of vasopressin (AVP) on ischemia/reperfusion (I/R) injury. Anesthetized male wistar rats were subjected to regional 30 min ischemia and 120 min reperfusion and randomly divided into nine groups: (1) Control; saline was administered intravenously before ischemia, (2) vasopressin was administrated 10 min prior to ischemia, (3, 4) Atractyloside as MPTP opener, was injected 5 min prior to reperfusion without and with vasopressin, (5, 6) Cyclosporine A as a MPTP closer, was injected 5 min prior to reperfusion without and with vasopressin, (7) mitochondria were isolated from control group and CaCl2 was added as MPTP opener and swelling inducer, (8) isolated mitochondria from Control hearts was incubated with Cyclosporine A before adding the CaCl2 (9) CaCl2 was added to isolated mitochondria from vasopressin group. Infusion of vasopressin decreased infarct size (18.6±1.7% vs. control group 37.6±2.4%), biochemical parameters [LDH (Lactate Dehydrogenase), CK-MB (Creatine Kinase-MB) and MDA (Malondialdehyde) plasma levels, PAB (Prooxidant-antioxidant balance)] compared to control group. Atactyloside suppressed the cardioprotective effect of vasopressin (32.5±1.9% vs. 18.6±1.7%) but administration of the Cyclosporine A without and with vasopressin significantly reduced infarct size to 17.7±4% (P<0.001) and 22.7±3% (P<0.01) respectively, vs. 37.6±2.4% in control group. Also, vasopressin, similar to Cyclosporine A, led to decrease in CaCl2-induced swelling. It seems that vasopressin through antioxidant effect and MPTP inhibition has created a cardioprotection against ischemia/reperfusion injuries. © 2015 Elsevier B.V. All rights reserved

Magnetic Moments of Heavy ΞQ\Xi_{Q} Baryons in Light Cone QCD Sum Rules

The magnetic moments of heavy $\Xi_{Q}$ baryons containing a single charm or bottom quark are calculated in the framework of light cone QCD sum rules method. A comparison of our results with the predictions of the quark models is presented.Comment: 26 Pages, 8 Figures and 1 Tabl

Pseudoscalar--meson decuplet--baryon coupling constants in light cone QCD

Taking into account the $SU(3)_f$ breaking effects, the strong coupling constants of the $\pi$, $K$ and $\eta$ mesons with decuplet baryons are calculated within light cone QCD sum rules method. It is shown that all coupling constants, even in the case of $SU(3)_f$ breaking, are described in terms of only one universal function. It is shown that for $\Xi^{\ast 0} \to \Xi^{\ast 0} \eta$ transition violation of $SU(3)_f$ symmetry is very large and for other channels when $SU(3)_f$ symmetry is violated, its maximum value constitutes $10$.Comment: 17 Pages, one Figure and 3 Table

Investigation on the functionality of thermoresponsive origami structures

Additive manufacturing (AM) has recently been introduced as a reliable technique for the fabrication of highly complex geometries that were not possible before. Due to the flexibility in the organization of material properties such as responsive elements in space, AM is now a capable technology for the production of smart structures that can transform their geometry, for example, from a compact state to a deployed configuration. Among others, fused deposition modeling (FDM) can reliably be used to manufacture polymeric constructs with high resolution. Polylactide (PLA), the most popular polymer in FDM printing is a shape-memory polymer. Therefore, the manufacturing of shape-transforming constructs can be simplified to the construction of foldable products that can be programmed simply by applying mechanical forces. Origami can then be used as a simple platform in which the shape-transforming of a programmed construct is via the folding of material through the thinner sections (hinges). Herein, PLA and FDM are used to fabricate foldable structures. The effects of different parameters namely total thickness, layer height, nozzle temperature, and activation temperature on the shape recovery of the manually programmed origami structures are then investigated

Nonlinear Vibrational Analysis of Nanobeams Embedded in an Elastic Medium including Surface Stress Effects

Due to size-dependent behavior of nanostructures, the classical continuum models are not applicable for the analyses at this submicron size. Surface stress effect is one of the most important matters which make the nanoscale structures have different properties compared to the conventional structures due to high surface to volume ratio. In the present study, nonlinear free vibrational characteristics of embedded nanobeams are investigated including surface stress effects. To this end, a thin surface layer is assumed on the upper and lower surfaces of the cross section to separate the surface and bulk of nanobeams with their own different material properties. Based on harmonic balance method, closed-form analytical solution is conducted for nonlinear vibrations to obtain natural frequencies of embedded nanobeams with and without considerations of surface elasticity and residual surface tension effects corresponding to the various values of nondimensional amplitude, elastic foundation modulus, and geometrical variables of the system. Selected numerical results are given to indicate the influence of each one in detail

Critical Thinking Skills in Nursing Students: a Comparison Between Freshmen and Senior Students

Background: Critical thinking is one of the most important concepts in the field of education. Despite studies published on nursing students’ critical thinking skills (CTS), some suggest that there is not enough evidence supporting the relationship between content of nursing education programs and nursing students’ CTS. Objectives: Given the existing discrepancies, this study aimed to compare the critical thinking skills of freshmen and senior nursing students. Patients and Methods: This comparative study was conducted on 150 undergraduate freshmen and senior nursing students in Kashan University of Medical Sciences, during 2012. The students in the first and the last semesters of their study in nursing were entered in the study using the census method. Data were collected using a questionnaire including questions on demographic data and the California Critical Thinking Skills Test, form B. Data analysis was performed using the SPSS v.13 software. Descriptive statistics were calculated. Moreover, independent sample t-test and Spearman and Pearson’s correlation coefficients were used in the data analysis. Results: Both the freshmen and senior nursing students had low CTS. The mean critical thinking scores were 11.79 ± 4.80 and 11.21 ± 3.17 for the freshmen and the senior students, respectively (P = 0.511). Moreover, no significant correlation was found between the students’ score in CTS and their age, gender, high school grade point average (GPA), rank in university entrance examination (RUEE) and interest in the nursing profession. Conclusions: The students were low skilled in critical thinking and their CTS did not significantly change during their nursing degree. Thus it may be concluded that the nursing education program did not affect the CTS of its students. Longitudinal studies are suggested for assessing nursing students’ critical thinking over time. Moreover, revising the curriculum and preparing nursing educators for implementing innovative and active teaching strategies are suggested