363 research outputs found
Formulation of Electrodynamics with an External Source in the Presence of a Minimal Measurable Length
In a series of papers, Quesne and Tkachuk (J. Phys. A: Math. Gen.
\textbf{39}, 10909 (2006); Czech. J. Phys. \textbf{56}, 1269 (2006)) presented
a -dimensional -two-parameter Lorentz-covariant deformed
algebra which leads to a nonzero minimal measurable length. In this paper, the
Lagrangian formulation of electrodynamics in a 3+1-dimensional space-time
described by Quesne-Tkachuk algebra is studied in the special case
up to first order over the deformation parameter . It is
demonstrated that at the classical level there is a similarity between
electrodynamics in the presence of a minimal measurable length (generalized
electrodynamics) and Lee-Wick electrodynamics. We obtain the free space
solutions of the inhomogeneous Maxwell's equations in the presence of a minimal
length. These solutions describe two vector particles (a massless vector
particle and a massive vector particle). We estimate two different upper bounds
on the isotropic minimal length. The first upper bound is near to the
electroweak length scale , while the
second one is near to the length scale for the strong interactions
. The relationship between the
Gaete-Spallucci nonlocal electrodynamics (J. Phys. A: Math. Theor. \textbf{45},
065401 (2012)) and electrodynamics with a minimal length is investigated.Comment: 13 pages, no figur
Reporting of Intimate Partner Violence among Men Who Have Sex with Men in an Online Survey
Objective: A growing body of literature suggests that IPV occurs within same-sex relationships and that members of the LGBT community face a number of unique challenges in accessing IPV related services. This paper examines the use of an on-line survey, marketed through a popular social networking site, to collect data on the experience and perpetration of IPV among men who have sex with men (MSM) in the US.Methods: Internet-using MSM were recruited through selective placement of banner advertisements on MySpace.com. Participants were eligible for the baseline survey if they were males ≥ 18 years of age, and reported at least one male sex partner in the last 12 months. In total 16, 597 men responded to the ad, of which 11, 681 were eligible for the study, and 5602 completed the questionnaire: in total 543 men completed the follow-up survey which included questions on the experience and perpetration of IPV. The final analysis sample was 402 MSM.Results: The prevalence of violence among the sample was relatively high: 11.8% of men reported physical violence from a current male partner, and about 4% reported experiencing coerced sex. Reporting of perpetration of violence against a partner was generally lower, with approximately 7% reporting perpetrating physical violence and less than 1% reporting perpetration of sexual violence.Conclusion: The results presented here find lower levels of experiencing both physical and sexual IPV than have been shown in previous studies, yet show relatively high levels of reporting of perpetration of IPV. Collecting IPV data through surveys administered through social networking sites is feasible and provides a new opportunity to reach currently over-looked populations in IPV research
The Relationship between Perfectionism, Achievement Motivation, Self-Esteem, and Academic Performance among Nursing Students
Background & Objective: Academic performance is the most important factor in student evaluation. Self-esteem is related to self-satisfaction and perfectionism is the setting of high goals in performance. Achievement motivation is the willingness to gain success. Because these variables can affect academic performance, the aim of this study was to investigate the relationship between students' perfectionism, achievement motivation, self-esteem, and academic performance.
Methods: This was a correlational-descriptive study. Based on Morgan's table, 97 students were randomly selected from all last year nursing students of Kerman Branch, Islamic Azad University. Due to being incomplete 7 questionnaires were excluded. The data collection tools consisted of Ahvaz Perfectionism Scale (APS), Hermans Achievement Motivation (HAMQ) Scale, and the Coppersmith Self-Esteem Inventory (SEI). Total average scores of students were considered as academic performance.
Results: Results showed a positive significant correlation between academic performance and perfectionism, achievement motivation, and self-esteem (P < 0.05). Perfectionism, achievement motivation, and self-esteem predicted 31% variances in academic performance. Nevertheless, investigation of the liner correlation of these variables showed that only the correlation between achievement motivation and academic performance was meaningful.
Conclusion: It is seems that for the improvement of students' academic achievement, perfectionism, self-esteem, and especially achievement motivation must be taken into consideration.
Keywords
Academic performance Perfectionism Self-Esteem Achievemen
Childhood Trauma Linked to Adult Waterpipe Smoking: A Survey of Health Science Students in Iran
Background: Explaining the risk and protective factors of waterpipe tobacco smoking (WTS) is the mostimportant principle in designing preventive interventions. This study examined the relationship betweenself-reported childhood abuse and WTS among health science students in Iran.Methods: This cross-sectional study was conducted among 776 health science students in Kerman City,located in southeast of Iran, who were selected by quota sampling approach. The study was performed usingtwo valid short instruments for measuring WTS and child abuse including physical, emotional, and sexualabuse using a self-report method.Findings: The prevalence of ever use and current use (last 30 days) of WTS among participants was 49.6%and 33.4%, respectively. The initiation age of WTS in 60% of students was < 18 years. Child sexual abuse(CSA) was [odds ratio (OR) = 3.05, 95% confidence interval (CI): 2.06-4.52, P < 0.001] the main predictorfor WTS among students.Conclusion: Protecting children during childhood to prevent them from becoming victims may be anessential primordial preventive strategy for WTS
Lightweight amorphous silicon photovoltaic modules on flexible plastic substrate
Solar cells on lightweight and flexible substrates have advantages over glass-or wafer-based photovoltaic devices in both terrestrial and space applications. Here, we report on development of amorphous silicon thin film photovoltaic modules fabricated at maximum deposition temperature of 150 degrees C on 100 mu m thick polyethylene-naphtalate plastic films. Each module of 10 cm x 10 cm area consists of 72 a-Si:H n-i-p rectangular structures with transparent conducting oxide top electrodes with Al fingers and metal back electrodes deposited through the shadow masks. Individual structures are connected in series forming eight rows with connection ports provided for external blocking diodes. The design optimization and device performance analysis are performed using a developed SPICE model
(E)-4-(2,5-DimethoxyÂbenzylÂidene)-2-phenyl-1,3-oxazol-5(4H)-one
The central azaÂlactone ring in the title compound, C18H15NO4, is planar (r.m.s. deviation 0.05, 0.12 Å) in both independent molÂecules comprising the asymmetric unit. The benzylÂidene substituent is coplanar with this ring [dihedral angle between the planes = 1.8 (1)° in the first molÂecule and 2.8 (1)° in the second], as is the phenyl substitutent [dihedral angle between rings = 4.6 (1) and 9.7 (1)°, respectively]
Lightweight amorphous silicon photovoltaic modules on flexible plastic substrate
Solar cells on lightweight and flexible substrates have advantages over glass-or wafer-based photovoltaic devices in both terrestrial and space applications. Here, we report on development of amorphous silicon thin film photovoltaic modules fabricated at maximum deposition temperature of 150 degrees C on 100 mu m thick polyethylene-naphtalate plastic films. Each module of 10 cm x 10 cm area consists of 72 a-Si:H n-i-p rectangular structures with transparent conducting oxide top electrodes with Al fingers and metal back electrodes deposited through the shadow masks. Individual structures are connected in series forming eight rows with connection ports provided for external blocking diodes. The design optimization and device performance analysis are performed using a developed SPICE model
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