Retrieval of interatomic separations of molecules from laser-induced high-order harmonic spectra

We illustrate an iterative method for retrieving the internuclear separations of N$_2$, O$_2$ and CO$_2$ molecules using the high-order harmonics generated from these molecules by intense infrared laser pulses. We show that accurate results can be retrieved with a small set of harmonics and with one or few alignment angles of the molecules. For linear molecules the internuclear separations can also be retrieved from harmonics generated using isotropically distributed molecules. By extracting the transition dipole moment from the high-order harmonic spectra, we further demonstrated that it is preferable to retrieve the interatomic separation iteratively by fitting the extracted dipole moment. Our results show that time-resolved chemical imaging of molecules using infrared laser pulses with femtosecond temporal resolutions is possible.Comment: 14 pages, 9 figure

Large displacements of FGSW beams in thermal environment using a finite element formulation

The large displacements of functionally graded sandwich (FGSW) beams in thermal environment  are studied using a finite element formulation. The beams are composed of three layers, a homogeneous core and two functionally graded face sheets with volume fraction of constituents following a power gradation law. The material properties of the beams are considered to be temperature-dependent.  Based on Antman beam model and the total Lagrange formulation, a two-node nonlinear beam element taking the effect of temperature rise into account  is formulated and employed in the study. The element with explicit expressions for the internal force vector and tangent stiffness matrix is derived using linear interpolations and reduced integration technique to avoid the shear locking. Newton-Raphson based iterative algorithm is employed in combination with the arc-length control method to compute the large displacement response of a cantilever FGSW beam subjected to end forces.  The accuracy of the formulated element is confirmed through a comparison study. The effects of the material inhomogeneity, temperature rise and layer thickness ratio on the large deflection response of the beam are examined and highlighted

Erratum: Mott Transition in the Mass Imbalanced Ionic Hubbard Model at Half Filling

Erratum: Mott Transition in the Mass Imbalanced Ionic Hubbard Model at Half Filling[Nguyen Thi Hai Yen, Le Duc Anh, Hoang Anh Tuan, Nguyen Toan Thang and Tran Thi Thu Trang, Communications in Physics, Vol. 29, No. 3SI (2019), pp. 305-312]This paper was published on 22 October 2019 with an omission in the text of the author’s list. The author list should read asNGUYEN THI HAI YEN$^1$, LE DUC ANH$^2$, HOANG ANH TUAN$^{1,3,\dagger}$, NGUYEN TOAN THANG$^1$, TRAN THI THU TRANG$^4$ AND NGUYEN THI HUONG$^5$$^1$Institute of Physics, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam $^2$Hanoi National University of Education, Hanoi, Vietnam $^3$Graduate University of Science and Technology, VAST, Hanoi, Vietnam $^4$Ha Long University, Quang Ninh, Vietnam $^5$Thuy Loi University, Hanoi, Vietnam$^{\dagger}$E-mail: [email protected] author’s list has been corrected as of 29 November 2019. The author’s list has been corrected in the electronic version of the journal

Challenges of Implementing Outcome-Based Assessment in Vietnamese Higher Education – A Qualitative Inquiry

This qualitative study investigates the key challenges faced by university lecturers in implementing outcome-based assessments (OBA) in higher education institutions in Vietnam, a country currently undergoing significant educational transformation. Utilizing a qualitative research design, the study conducted semi-structured interviews with 15 lecturers from diverse academic fields in a institution. The data were thematically coded and interpreted through the lenses of Constructivism, Institutional Theory, and Diffusion of Innovations Theory. Nine major challenges emerged from the findings, including pedagogical hurdles, lack of training and resources, institutional constraints, and technological limitations. These challenges are contextualized within the existing theoretical frameworks and related literature. The study offers critical insights that are deeply rooted in cultural, institutional, and structural variables. These findings are pertinent for educators, administrators, and policymakers in Vietnam and potentially for those in similar educational settings, and they hold broader implications for professional development, institutional policies, technological infrastructure, and cultural shifts within the educational landscape

Survey on Vietnamese teachers’ perspectives and perceived support during COVID-19

The COVID-19 pandemic has caused unprecedented damage to the educational system worldwide. Besides the measurable economic impacts in the short-term and long-term, there is intangible destruction within educational institutions. In particular, teachers – the most critical intellectual resources of any schools – have to face various types of financial, physical, and mental struggles due to COVID-19. To capture the current context of more than one million Vietnamese teachers during COVID-19, we distributed an e- survey to more than 2,500 randomly selected teachers from two major teacher communities on Facebook from 6th to 11th April 2020. From over 373 responses, we excluded the observations which violated our cross-check questions and retained 294 observations for further analysis. This dataset includes: (i) Demographics of participants; (ii) Teachers' perspectives regarding the operation of teaching activities during the pandemic; (iii) Teachers' received support from their schools, government bodies, other stakeholders such as teacher unions, and parents' associations; and (iv) teachers' evaluation of school readiness toward digital transformation. Further, the dataset was supplemented with an additional question on the teachers' primary source of professional development activities during the pandemic

In-action reflective teaching in Vietnam: A qualitative exploration of practices, influences and implications

Reflective teaching plays a crucial role in the field of education though its intricacies in particular cultural contexts like Vietnam are still little understood. This study aims to investigate reflective teaching practices in more detail within the context of Vietnamese education.  This study used a qualitative methodology and semi-structured interviews with twelve Vietnamese teachers, each representing a different stage of their careers to shed light on the many forms of in-action reflective practices and their implementation, benefits, drawbacks and even cultural influences. The results of this in-depth investigation provided an overview of the wide range of in-action reflective practices that are actively used in the classroom.  The enhancement of adaptive teaching methodologies and the bolstering of student engagement are prominent among the many advantages that were noted.  Teaching in the Vietnamese context also presents unique challenges. Teachers often struggle with the demands of multitasking, the complexities of navigating uncertainties in real-time classroom scenarios   and the predominant challenge of managing large class sizes. Moreover, it was surprising to learn how many Vietnamese cultural, social   and educational factors influenced teacher understanding and use of in-action reflection.  The understanding of reflective teaching practices is enhanced by the research findings which also have broad implications for areas such as instructional strategies, teacher preparation programmes, academic research perspectives and even the development of educational policies.  The study strongly emphasizes the pressing need for more context-specific investigations into reflective teaching and underscores the indispensable role of reflection in fostering an environment conducive to effective teaching and learning

Multi-faceted identities of teacher assessors: A qualitative study in the Vietnamese educational context

Within the educational landscape of Vietnam, the professional identity of teachers when acting as assessors remains a comparatively uncharted domain and requires further explorations. Consequently, this qualitative investigation was initiated to delve deeper into the intricate identities Vietnamese teachers adopt in their capacities as assessors. Relying upon frameworks such as Constructivist Grounded Theory and Identity Theory, the study meticulously analyzed self-reported narratives from 15 tertiary lecturers based in Vietnam. Through this rigorous analysis, a spectrum of fifteen distinct identities was uncovered. These identities included “Gatekeepers of Knowledge and Competency”, “Nurturers”, “Diplomatists”, “Auditors”, “Confusian Sages”, “Innovators”, “Social Justice Advocators”, “Cultural Mediators”, “Emotional Anchors”, “Scalfolders”, “Technological Navigators”, “Lifelong Learners”, “Community Builders”, “Ethical Guardians”, and “Democratic Facilitators.” Intriguingly, these identities were not merely seen as additional layers to their professional duties; instead, they emerged as foundational components of teachers’ professional self-image. The forces molding these roles are diverse, encompassing deep-seated cultural values, prevailing educational paradigms, and personal lived experiences of educators. Unraveling these identities offers consequential implications for the broader educational sector. It underscores the imperative to holistically re-envision teacher training programs and assessment design, ensuring they resonate with the multifaceted roles educators play in steering both academic achievements and wider societal outcomes

Determination of the Administration Routes, Doses and Appropriate Age to Vaccinate With Ornitin Triple Vaccine For Cross-breed Colored Broilers in Vietnam

The study was to determine the appropriate dose and administration route of Ornitin Triple vaccine in cross-breed coloured broilers in Vietnam by evaluating the antibody titer against Ornithobacterium rhinotracheale (ORT) and local reactions at injection sites on chickens after vaccination. The study was divided into 2 trials. Both trials were designed with 3 vaccine dose groups: 0.0ml (control group), 0.25ml and 0.5ml and 2 different administration routes: subcutaneous at neck (SC) and intramuscular at breast (IM) injection. The result showed that, no statistically significant difference was found between antibody titer of two administration routes as well as 2 vaccine doses until 13-week-old. Local reactions at the injection sites of IM route was less severe than SC at neck and in higher dose would produce a more severe swelling reaction. Daily weight gain was found to have a slight decrease in the vaccinated groups within 2 weeks after vaccination, however, no statistically significant difference was found in later stage (P > 0.05). In conclusion, Ornitin Triple can be used to vaccinate by IM with the dose of 0.25ml for coloured broilers at early age (3-week-old), or 0.5ml for older birds and should be careful for some reactions at the injection sites