A preliminery study on length-weight relationship of the mudskipper Boleophthalmus boddarti in Soc Trang

Boleophthalmus boddarti (Pallas, 1770) is one of mudskippers (Gobiidae), and a potential commercial fish in Mekong Delta, Vietnam. The study on the goby B. boddarti was investigated in Tran De district, Soc Trang province, Mekong Delta, Vietnam, to establish some basic population biology parameters. A total of 117 individuals were caught in mudflats of Tran De beach by deep net to determine length-weight relationships of this species. After determining sex by external features, total length (TL in cm), and body weight (W in g) of this goby were measured. This study ran for six months, from January 2013 to June 2013. The mean lengths of female significantly differed from value of male, whereas the average body weights of male and female were quite similar. The proportion of male and female groups were not substantially different. The length-weight relationships of total fish, male and female were highly correlated with high regression values which were 0.813, 0.866 and 0.767, respectively. The slope values of this mudskipper was 3.21±0.32 which was not significant higher cubic value (three), suggesting the growth relationship of this species was isometric growth and could be a potential fish for future aquaculture

Preliminary study on dietary composition, feeding activity and fullness index of Boleophthalmus boddarti in Mekong delta, Vietnam

The mudskipper Boleophthalmus boddarti (Pallas, 1770) is an important commercial fish, but information on its dietary composition has been limited. This study was carried out from March 2013 to February 2014, in Tran De, Soc Trang, Mekong Delta, Vietnam to understand its food, foraging intensity and fullness index. A total of 120 fish specimens including 63 females (8-15 cm in TL) and 57 males (9.5-15.1 cm in  TL) were collected and analysed. The results showed that the sex ratio of B. boddarti was close to 1:1 and this mudskipper would be a herbivorous fish due to high relative gut length value (RGL1) based on 120 gastrointestinal tract length analysis. Among them, 75 fish stomachs were used for food item determination. The B. boddarti fed mainly on Bacillariophyta (82.97%), and detritus was also composed in its stomach contents (13.26%). The mudskipper showed high in foraging intensity due to high fullness index value. The variation of food composition of this fish depended on season, but not in gender and fish size. The results provided useful information on diet composition of B. boddarti and contributed to our knowledge for other gobies living in the monsoonal regions.

A model with vectorlike fermions and U(1)XU(1)_X symmetry: CKM unitarity, b→sb \rightarrow s transitions, and prospect at Belle II

To address the muon $g-2$ anomaly and the violation of the lepton flavor universality in the semileptonic decays of $B$ mesons, B\'elanger, Delaunay, and Westhoff introduced a new sector consisting of vectorlike fermions and two scalar charged under an extra $U(1)_X$ gauge symmetry. The exotic Yukawa interactions in this model lead to the quark mixing responsible for the additional contributions to the flavor changing neutral currents in $B$-meson decays. In this paper, we derive the analytic expression of the new physics contributions to the Wilson coefficient $C_7$ in the effective Hamiltonian. By calculating the branching ratio of the inclusive radiative $B$ decay, the impact of current experimental data of the $b \rightarrow s \gamma$ transition on the model and the future prospect at the Belle II experiment are investigated. Taking into account the recent data on the CKM unitarity violation, the updated constraints on the flavor observables relevant to the $b \rightarrow s$ transitions, and the perturbation limits of the couplings, the viable parameter regions of the model are identified.Comment: 28 pages, 14 figure

Muon g−2g-2 and semileptonic BB decays in B\'elanger-Delaunay-Westhoff model with gauge kinetic mixing

In the model proposed by B\'elanger, Delaunay and Westhoff (BDW), a new sector consisted of vectorlike fermions and two complex scalars is charged under an extra Abelian symmetry $U(1)_X$. In this paper, we generalize the BDW model by introducing the kinetic mixing between the $U(1)_X$ and the standard model $U(1)_Y$ gauge fields. The new physics contributions to the muon anomalous magnetic moment and the Wilson coefficients $C_{9,10}^{(')}$ are obtained analytically. We have explored the free parameter space of the model, taking into account various constraints on the muon $g-2$ using recent data from the E989 experiment at Fermilab, the lepton universality violation in terms of $R_K$ and $R_{K^*}$, and the branching ratios of the semileptonic decays, $B^+ \rightarrow K^+ \mu^+ \mu^-$ and $B^0 \rightarrow K^{*0} \mu^+ \mu^-$, the LEP and LHC searches for sleptons and $Z'$ boson, as well as the perturbative requirement. The viable parameter regions of the model are identified. In the presence of the gauge kinetic mixing term, those regions are enlarged and significantly deformed in comparison to the case with vanishing kinetic mixing. In the near future, the E989 experiment with the projected sensitivity will be able to test significant parts of the currently allowed parameter regions.Comment: 36 pages, 23 figures. Version to be published in Physical Review

On a Standard Model Extension with Vector-like Fermions and Abelian Symmetry

We investigate an extension of the standard model with vector-like fermions and an extra Abelian gauge symmetry. The particle mass spectrum is calculated explicitly. The Lagrangian terms for all the gauge interactions of leptons and quarks in the model are derived. We observe that while there is no new mixing in the lepton sector, the quark mixing plays an important role in the magnitudes of gauge interactions for quarks, particularly the interactions with massive $W$, $Z$ and $Z'$ bosons. We calculate the contributions of the new vector-like leptons and quarks to the Peskin-Takeuchi parameters as well as the $\rho$ parameter of the electroweak precision tests, and show that the model is realistic

Biological Characteristics of Some Fish Species in the Mekong Delta, Vietnam

Vietnam, with a rich river system, many lagoons, and a long coastline, the fish fauna comprises both brackish and freshwater fish. The system of Mekong river is an extensive river located in the south of Vietnam. There are all kinds of brackish and freshwater fish in this river system. This chapter reveals data on the fish species composition and their roles in the Vietnamese Mekong delta. Moreover, the growth pattern and condition factor of some commercial fishes are also presented in this chapter. Their population structure and fishing status are also reported in this chapter

Procedure for performing a fixed microscopic specimen of the gonads of fish

This study aims to provide a procedure for performing microscopy in fish gonads. Specimens used in this study were the ovaries and testes of fish collected in the Mekong Delta from April to July 2022. Organs at five different stages for each sex (ovary diameter from 1.16 cm in stage I to 4.04 cm in stage V; testis diameter from 0.42 in stage I to 2.39 in stage V) were studied in this procedure. The results showed that both ovaries and testes needed to be fixed at 4% formol for 24 h and under running water for eight hours. Ovaries and testes were then immersed in 500 ethanol for 24 h to initiate dehydration. Results showed that the time for dehydration and paraffin infiltration was longer in the ovary (26 to 55 h across stages) than in the testis (25 to 26 h across stages). The mean staining time of the ovary was 1.5 min (stage I) to 3.5 min (stage V) in Hematoxylin and 50 s (stage I) to 140 s (stage V) in Eosin. Whereas the staining time of testis was shorter, 1 min (stage I) to 3 min (stage V) in Hematoxylin and 30 s (stage I) to 90 s (stage V) in Eosin. This study provides a reference for further studies on the histological structure of fish gonads. These results could be applied to fish species inside and outside the Mekong Delta

Optimal control and real-time simulation of hybrid marine power plants

With significantly increasing concerns about greenhouse effects and sustainable economy, the marine industry presents great potential for reducing its environmental impact. Recent developments in power electronics and hybridisation technologies create new opportunities for innovative marine power plants which utilize both traditional diesel generators and energy storage like batteries and/or supercapacitors as the power sources. However, power management of such complex systems in order to achieve the best efficiency becomes one of the major challenges. Acknowledging this importance, this research aims to develop an optimal control strategy (OCS) for hybrid marine power plants. First, architecture of the researched marine power plant is briefly discussed and a simple plant model is presented. The generator can be used to charge the batteries when the ship works with low power demands. Conversely, this battery energy can be used as an additional power source to drive the propulsion or assist the generators when necessary. In addition, energy losses through braking can be recuperated and stored in the battery for later use. Second, the OCS is developed based on equivalent fuel consumption minimisation (EFCM) approach to manage efficiently the power flow between the power sources. This helps the generators to work at the optimal operating conditions, conserving fuel and lowering emissions. In principle, the EFCM is based on the simple concept that discharging the battery at present is equivalent to a fuel burn in the future and vice-versa and, is suitable for real-time implementation. However, instantaneously regulating the power sources’ demands could affect the system stability as well as the lifetime of the components. To overcome this drawback and to achieve smooth energy management, the OCS is designed with a number of penalty factors by considering carefully the system states, such as generators’ fuel consumption and dynamics (stop/start and cranking behaviour), battery state of charge and power demands. Moreover, adaptive energy conversion factors are designed using artificial intelligence and integrated in the OCS design to improve the management performance. The system therefore is capable of operating in the highest fuel economy zone and without sacrificing the overall performance. Furthermore, a real-time simulation platform has been developed for the future investigation of the control logic. The effectiveness of the proposed OCS is then verified through numerical simulations with a number of test cases

RESEARCH ON NEARSHORE WAVE CONDITIONS AT NHAT LE COASTAL AREA (QUANG BINH PROVINCE) BY USING MIKE21-SW

Research on marine dynamics, including coastal wave motions, is a concern of countries in the world in general and Vietnam in particular. Coastal wave dynamics has a direct impact on human activities including coastal construction, shipping, irrigation, aquatic resources exploitation, etc. The coastal area of Nhat Le, Quang Binh is one of the areas strongly influenced by the coastal wave regime which increases the risk of coastal erosion, estuarine sedimentation, destroys the economic life, affects marine fishing and directly affects the tourist beach area. This article aims to introduce some research results based on the application of MIKE21-SW model of the Danish Hydraulic Institute (DHI) to simulate coastal wave regime in Nhat Le coastal zone, Quang Binh province. The model results are verified by real-time wave data in long-term from the WaMoS® II Radar System at Quang Binh station. The results show that there are many similarities in wave height and direction between the computational model and the actual observation data from the radar system. This result will be an important basis for research and application for coastal protection, reduction in river mouth sedimentation, clearing and flood drainage in the study area

Analysis of Electromagnetic Parameters of Hybrid Externally Excited Synchronous Motors for Electric Vehicle Applications

This paper presents two different approaches to improve the electromagnetic torque and output power of the hybrid Externally Excited Synchronous Motor (EESM) applied to Electric Vehicles (EVs). An analytical approach is first considered to define the main parameters of the proposed machine. Based on the obtained results from the analytical model, the hybrid EESM is designed with different rotor shapes and step-skewing magnet segments to reduce the total losses and improve torque ripple. Then, Finite Element Analysis (FEA) is applied to compute and simulate electromagnetic parameters, such as the magnetic flux density, mean torque, and output power. The development of these two approaches is validated on an actual EESM machine and the agreement with the theory is shown