2,181 research outputs found
Influences of Teachers, Students and School Climate on Bullying Victimization: Evidence from China
Given the common occurrence of school bullying incidents and high prevalence rates of victimization in China, this study aims to explore the association between multiple school-related predictors and Chinese adolescents’ overall experiences with bullying victimization. Guided by the social-ecological framework for violence prevention, this study integrated different factors involving teachers, students, and school climate into one single research to detect the bullying problem more systematically and holistically. Further, the study applied the data from the 2018 Program for International Student Assessment while utilizing binary logistic regression analyses to perceive anti-bullying variables and their relationships with bullying victimization. The study revealed that teachers’ emotional, instrumental, and informational support other than appraisal support were negatively associated with students’ experiences of being bullied and victimized. The research also indicated that students’ sense of belonging, a cooperative school environment, and classroom disciplinary climate played a buffering role in bullying victimization while competition in school settings adversely increased overall bullying exposure. The results have highlighted the integration of various predictors in influencing multiple social relations and school environments to battle against in-person bullying. The results also have implications for stopping cyberbullying to achieve inclusive school education for all in the post-COVID-19 era
The global symmetry in the flavor-unified theories
We study the origin of the global symmetry in a class of flavor-unified
theories with gauge groups of . In particular, we focus on
the theory which can minimally embed three-generational SM
fermions non-trivially. A reformulation of the third law for the flavor sector
proposed by Georgi is useful to manifest the underlying global symmetries. The
't Hooft anomaly matching and the generalized neutrality conditions for Higgs
fields play the key roles in defining the symmetry. Based on the global
symmetry, we count the Higgs fields that can develop the VEVs and the
massless sterile neutrinos in the theory. We also prove that a
global symmetry can always be defined in any theory
when it is spontaneously broken to the SM gauge symmetry.Comment: 34 pages, 11 table
Reductive dechlorination of polychlorinated biphenyls is coupled to nitrogen fixation by a legume-rhizobium symbiosis
Chlorinated persistent organic pollutants, including polychlorinated biphenyls (PCBs), represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic bacteria (rhizobia) are important components of the biogeochemical cycling of nitrogen in both agricultural and natural ecosystems. However, there have been relatively few detailed studies of the remediation of PCB-contaminated soils by legume-rhizobia symbionts. Here we report for the first time evidence of the reductive dechlorination of 2,4,4'-trichlorobiphenyl (PCB 28) by an alfalfa-rhizobium nitrogen fixing symbiont. Alfalfa (Medicago sativa L.) inoculated with wild-type Sinorhizobium meliloti had significantly larger biomass and PCB 28 accumulation than alfalfa inoculated with the nitrogenase negative mutant rhizobium SmY. Dechlorination products of PCB 28, 2,4'-dichlorobiphenyl (PCB 8), and the emission of chloride ion (Cl-) were also found to decrease significantly in the ineffective nodules infected by the mutant strain SmY. We therefore hypothesize that N2-fixation by the legume-rhizobium symbiont is coupled with the reductive dechlorination of PCBs within the nodules. The combination of these two processes is of great importance to the biogeochemical cycling and bioremediation of organochlorine pollutants in terrestrial ecosystems.</p
First-principles study on the effective masses of zinc-blend-derived Cu_2Zn-IV-VI_4 (IV = Sn, Ge, Si and VI = S, Se)
The electron and hole effective masses of kesterite (KS) and stannite (ST)
structured Cu_2Zn-IV-VI_4 (IV = Sn, Ge, Si and VI = S, Se) semiconductors are
systematically studied using first-principles calculations. We find that the
electron effective masses are almost isotropic, while strong anisotropy is
observed for the hole effective mass. The electron effective masses are
typically much smaller than the hole effective masses for all studied
compounds. The ordering of the topmost three valence bands and the
corresponding hole effective masses of the KS and ST structures are different
due to the different sign of the crystal-field splitting. The electron and hole
effective masses of Se-based compounds are significantly smaller compared to
the corresponding S-based compounds. They also decrease as the atomic number of
the group IV elements (Si, Ge, Sn) increases, but the decrease is less notable
than that caused by the substitution of S by Se.Comment: 14 pages, 6 figures, 2 table
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