Evaluation of genetic diversity of Vietnamese dogs based on mitochondrial DNA hypervariable-1 region

Haplogroup E were detected with high frequency in the population of Phu Quoc ridgeback dogs suggesting that this Vietnamese valuable dog breed originated from domestic dogs harbouring haplogroup E from Vietnam’s mainland or from East Asia where the presence of haplogroup E was reported. Evaluation of the genetic diversity of the Vietnam’s mainland dogs and haplogroup Escreening would support us in tracking out the origin of Phu Quoc ridgeback dog

Caenorhabditis Elegans Sperm Chemotaxis

Survival of animal species depends on fertilization, the union of an egg and a sperm. The sperm\u27s ability to find an egg quickly allows it to pass on male genetic material. It is challenging to record sperm targeting or guidance efficiency and motility in utero. We use the Caenorhabditis elegans model organism to study sperm guidance, primarily because its epidermis is transparent, allowing the observation of live fluorescent sperm in the hermaphrodite uterus. Using genome-editing techniques, genetic analyses, fluorescent microscopy, and mass spectrometry, we aim to address the following two questions: how hermaphrodites regulate sperm motility in the uterus, and how males respond to hermaphrodite cues. Chapter one gives a general introduction about fertilization, factors affecting fertilization, and sperm motility. Next, background on sperm guidance in externally and internally fertilizing species is given. Given the difficulty of observing sperm in utero in mammals, Caenorhabditis elegans provides a powerful model system to study sperm guidance. Recent findings suggest that prostaglandin-like lipids derived from C. elegans oocytes may be sperm chemoattractants. An introduction to prostaglandins, their diverse roles, their synthesis, and receptors is provided. Then background is presented on the potential impact of environment on fertility and sperm guidance. Finally, the C. elegans sensory nervous system, which is used to sense environmental cues, is discussed. In chapter two, we use genetics, liquid chromatography, and electrospray ionization tandem mass spectrometry (LC-MS/MS) to investigate prostaglandin metabolism in C. elegans hermaphrodites. Our results show that C. elegans oocytes or their precursors produce more than ten structurally related F-series prostaglandins (PGFs), which function redundantly to promote sperm targeting. PGFs are derived from omega-3 and omega-6 polyunsaturated fatty acids (PUFAs). Specifically, PGF1 stereoisomers are derived from dihomo-gamma-linolenic acid (DGLA), PGF2 stereoisomers are derived from arachidonic acid (AA) and omega-3-arachidonic acid (O3AA), and PGF3 stereoisomers are derived from eicosapentaenoic (EPA) acid. Genetic ablation of omega-3 PUFA synthesis causes a compensatory increase in production of PGFs derived from omega-6 PUFAs. C. elegans PGF synthesis occurs independent of cyclooxygenase (COX) enzymes, which initiate PGF synthesis in mammals. COX-independent PGFs containing different stereochemical configurations than PGF2α are found in mouse tissues. Finally, we identify an evolutionarily conserved cytochrome P450 enzyme that negatively regulates PGF synthesis. In chapter three, we use genome-editing and transgenic techniques, fluorescence microscopy, quantitative RT-PCR, and RNAseq to investigate the role of a G-protein coupled receptor (GPCR) subfamily in sperm guidance. We show that at least three candidate chemoreceptor GPCRs called SRB-13, SRB-16, and SRB-5 are essential in males to promote efficient sperm guidance. These SRB subfamily chemoreceptors act in at least two parallel pathways. The GOA-1 Gαi/o protein appears to be a common downstream component required for sperm guidance. srb mutant sperm are activated and motile, but do not efficiently target the fertilization site and thus, appear of poor quality. Surprisingly, SRB chemoreceptors are not expressed in sperm. Instead, they (e.g. SRB-13 and SRB-16) are expressed in male head neurons, including amphid sensory neurons that perceive environmental cues. SRB-13 is specifically expressed in the cilia of ASI and ASK amphid sensory neurons, whereas SRB-16 is expressed in cell bodies and dendrites of ASH, ASI, ASK, and AWB amphid sensory neurons. SRB-16 is also expressed in I1 pharyngeal interneurons, pm4 and pm5 pharyngeal muscles, and other unidentified male neurons. Expressing srb-16 in neurons rescues the srb-16 null mutant sperm guidance defect. Similarly, expressing srb-13 in sensory neurons rescues the srb-13 null mutant defect. RNAseq studies suggest that SRB-13 and SRB-16 regulate spermatogenic gene transcription, possibly by modulating a neuroendocrine pathway(s). Together, these data support the unexpected model that male SRB chemoreceptors couple environmental information to sperm quality. Chapter four ends the thesis by discussing additional published and unpublished data, as well as discussing remaining outstanding questions. Experimental evidence is provided that COX knockout mice synthesize PGFs. These data were published in a collaborative study with Dr. Katherine McKnight. Unpublished data document efforts to identify enzymes essential for PGF synthesis. The thesis ends with a model for the mechanisms controlling sperm guidance (a.k.a. chemotaxis) and concluding remarks on the power of the C. elegans model for generating endless exciting questions

PERCEPTIONS OF SCIENCE HIGH SCHOOL STUDENTS TOWARD BLENDED TEACHING

Under the impact of the COVID 19 pandemic, it is a must for education institutes all over the world to incorporate online teaching into their teaching program. In Vietnam, high school teachers and students are now familiar with blended teaching in which students will learn from at least 30% of their lessons online and 70% face-to-face. This research aims at investigating Vietnamese high school students’ perceptions toward the benefits and challenges of blended teaching. Two research questions will be answered (1) “What are high school students’ perceptions toward the benefits of blended teaching?” and (2) “What are high school students’ perceptions toward the challenges of blended teaching?”. There were 200 sciences students (72 participants majoring in Physics, 60 in Chemistry, and 68 in Biology) from 3 high schools for the gifted in Vietnam who participated in the study. The results of the research show that the majority of participants agreed on the benefits and challenges of blended teaching in the context of high school for the gifted in Vietnam. The current study suggests that teachers should have an effective lecture design to help their students acquire science knowledge better in blended classes.  Article visualizations

Buckling and postbuckling of axially-loaded CNT-reinforced composite cylindrical shell surrounded by an elastic medium in thermal environment

Buckling and postbuckling behaviors of nanocomposite cylindrical shells reinforced by single walled carbon nanotubes (SWCNTs), surrounded by an elastic medium, exposed to a thermal environment and subjected to uniform axial compression are investigated in this paper. Material properties of carbon nanotubes (CNTs) and isotropic matrix are assumed to be temperature dependent, and effective properties of nanocomposite are estimated by extended rule of mixture. The CNTs are embedded into matrix via uniform distribution (UD) or functionally graded (FG) distribution along the thickness direction. Governing equations are based on Donnell’s classical shell theory taking into account von Karman-Donnell nonlinear terms and interaction between the shell and surrounding elastic medium. Three-term form of deflection and stress function are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to obtain load-deflection relation from which buckling and postbuckling behaviors are analyzed. Numerical examples are carried out to analyze the effects of CNT volume fraction and distribution types, geometrical ratios, environment temperature and surrounding elastic foundation on the buckling loads and postbuckling strength of CNTRC cylindrical shells

The QCD heavy-quark potential to order v^2: one loop matching conditions

The one-loop QCD heavy quark potential is computed to order v^2 in the color singlet and octet channels. Several errors in the previous literature are corrected. To be consistent with the velocity power counting, the full dependence on |p' + p|/|p' - p| is kept. The matching conditions for the NRQCD one-loop potential are computed by comparing the QCD calculation with that in the effective theory. The graphs in the effective theory are also compared to terms from the hard, soft, potential, and ultrasoft regimes in the threshold expansion. The issue of off-shell versus on-shell matching and gauge dependence is discussed in detail for the 1/(m k) term in the potential. Matching on-shell gives a 1/(m k) potential that is gauge independent and does not vanish for QED.Comment: 28 pages, References added and minor changes to section III, results unchange

FOC-Based Soft Start of Induction Motors Using Trigonometric S-Curve

This paper presents a novel approach to improving the starting performance of three-phase induction motors by integrating an optimized S-curve acceleration profile based on trigonometric functions into a Field-Oriented Control (FOC) framework. Unlike conventional third- and fifth-order polynomial trajectories that suffer from limited jerk continuity and insufficient mechanical damping, the proposed method ensures smooth transitions in acceleration and jerk using sinusoidal functions. The core contribution of this work lies in the development and application of a second-order continuous trigonometric velocity trajectory that significantly reduces mechanical shocks and current oscillations during motor startup and stop phases. Furthermore, the method is designed for real-time implementation on FPGA hardware, enabling high-resolution pulse-width modulation (PWM) suitable for embedded motion control systems. Simulation and experimental results demonstrate superior motion smoothness, improved torque tracking, and enhanced mechanical reliability compared to traditional methods. This research provides a practical and effective solution for applications requiring precise soft-start/stop capabilities, particularly in elevator systems and other high-performance industrial drives