Gene Polymorphisms That Predispose Women for Down Syndrome Child Birth

Down syndrome caused by presence of extra chromosome 21 originates from nondisjunction during parental gametogenesis. For overwhelming cases, the error occurs in oocyte and all the nondisjunction events are not stochastic. With increasing number of research efforts, it has come to know that maternal genetic architecture may be considered as risk factors for chromosomal errors. Polymorphisms of the genes involved in chromosome segregation, recombination and folic acid metabolisms have been investigated for their association with Down syndrome child birth. But the results are conflicting owing to ethnic and sociocultural differences. Here, we have discussed and summarized the outcome of the studies conducted on different population sample from different parts of world and tried to figure out the common polymorphisms, which could be used as makers for preconceptional screening of Down syndrome child birth risk among the women

Bisphenol A: Understanding Its Health Effects from the Studies Performed on Model Organisms

Bisphenol A [4,4′‐(propane‐2,2‐diyl)diphenol] (abbreviated as BPA) is a synthetic xenoestrogenic chemical and endocrine disruptor. It is a most common plasticizer that is used widely to produce epoxy resin and polycarbonate plastics, enters the living system through food and water contamination and generates health hazards. Researches are being conducted to explore the adversity that BPA exerts in living body, and for this reason, model organisms are of scientific choice. Rodents, zebrafish, Drosophila, nematodes, crustaceans and echinoderms are being used for monitoring the effect of BPA on their life history traits, nervous system, endocrine system, reproductive systems, behaviour, etc., which could help us to anticipate what kind of challenges BPA is putting in human life. This systematic review is focused on the latest research trend on BPA toxicity on different model organisms

Nonlinear Stability Assessment Of Type-4 Wind Turbines During Unbalanced Grid Faults Based On Reduced-Order Model

As the number of converter-based renewable generations in the power system is increasing, the inertia provided by the synchronous generators is reducing, which in turn is reducing the stability margins of the power system. In order to assess the large-signal stability, it is essential to model the wind power plant connections accurately. However, the actual EMT models are often unavailable, black-boxed, or computationally too heavy to model in detail. Hence, simplified reduced-order models (ROMs) resembling the actual system behaviour have gained prominence in stability studies. In this regard, an improved WT ROM was proposed to investigate large signal stability during unbalanced grid faults. The methodology presents a systematic way to model the coupled sequence components of the WT ROM for various grid faults. Based on the studies carried out in this paper, it is observed that post unbalanced grid disturbances the proposed WT ROM correctly tracks the angle and frequency, and its trajectory is a good match when compared to a detailed simulation model in PSCAD

An Improved Nonlinear Stability Assessment Methodology For Type-4 Wind Turbines via Time Reversal Trajectory

As the integration of renewable energy generation increases and as conventional generation is phased out, there is a gradual decline in the grid's strength and resilience at the connection point of wind turbines (WTs). Previous studies have shown that traditional grid-following controlled converters exhibit deteriorating dynamic characteristics and may result in an unstable system when connected to a weak grid. Due to the limitations of linear analysis, transient stability investigations are necessary. However, existing methods, such as standalone time-domain simulations or analytical Lyapunov stability criteria, have drawbacks, including computational intensity or excessive conservatism. Our prior research proposed an innovative approach to estimate the system boundary - a time-limited region of attraction (TLRoA), using a hybrid linearised Lyapunov function-based method and the time-reversal technique to compensate for the known limitations. However, in that work, the accuracy of the estimated TLRoA was not investigated, i.e. the TLRoA was not compared against a forward simulated region of attraction, and the sensitivity of the system parameters on the TLRoA was not explored. Moreover, the framework did not consider nonlinear control elements such as PLL saturation. In this paper, we not only build upon our previous work and propose directions that address these gaps but also enhance its effectiveness by introducing optimal sampling to improve further the speed of estimating the TLRoA. Furthermore, the stability boundary is verified using time-domain simulation studies in PSCAD

Nonlinear Stability Boundary Assessment Of Wind Power Plants Based on Reverse-Time Trajectory

This letter determines the nonlinear stability boundary of a wind power plant (WPP) connected to an AC power grid via a long HVAC cable. The analysis focuses on the slow Phase-Locked Loop (PLL) dynamics, with an assumption that the fast current control dynamics can be neglected. To begin, we propose an aggregated reduced-order wind turbine model. This aggregation can be applied up to a limited frequency, e.g. 400Hz, which aligns with our assumption regarding low-frequency dynamics. The WPP collector and transmission network model is established using impedance/frequency scan approximated around $\pm$5 Hz of the PLL nominal frequency, accounting for the hard saturation limits. The stability boundary of the reduced-order system is determined by reverse time trajectory, offering valuable insights into the WPP's overall stability. The work presents a routine from modelling to nonlinear stability assessment for offshore wind farm applications

Modulacijska nestabilnost visokofrekventnih površinskih valova na granici plazma – vakuum

Nonlinear propagation of surface waves in a cold electron-plasma half-space is theoretically investigated by using the method of multiple scale. It is shown that high-frequency surface waves are modulationally unstable at a plasma - vacuum interface. The growth of the modulational instability of the surface waves is discussed. It is also shown that the electric field associated with a finite amplitude surface wave can take the form of an envelope soliton which propagates along the plasma - vacuum interface with a velocity independent of the soliton height.Teorijski istražujemo nelinearno širenje površinskih valova u poluprostoru s hladnom elektronskom plazmom metodom višestruke ljestvice. Pokazuje se da su visokofrekventni površinski valovi modulacijski nestabilni na granici plazma – vakuum. Raspravlja se rast modulacijske nestabilnosti površinskih valova. Također pokazujemo da električno polje, koje je povezano s površinskim valovima konačne amplitude, može primiti oblik anvelopnog solitona koji se širi duž granice plazma – vakuum brzinom koja ne ovisi o visini solitona

Modulacijska nestabilnost visokofrekventnih površinskih valova na granici plazma – vakuum

Nonlinear propagation of surface waves in a cold electron-plasma half-space is theoretically investigated by using the method of multiple scale. It is shown that high-frequency surface waves are modulationally unstable at a plasma - vacuum interface. The growth of the modulational instability of the surface waves is discussed. It is also shown that the electric field associated with a finite amplitude surface wave can take the form of an envelope soliton which propagates along the plasma - vacuum interface with a velocity independent of the soliton height.Teorijski istražujemo nelinearno širenje površinskih valova u poluprostoru s hladnom elektronskom plazmom metodom višestruke ljestvice. Pokazuje se da su visokofrekventni površinski valovi modulacijski nestabilni na granici plazma – vakuum. Raspravlja se rast modulacijske nestabilnosti površinskih valova. Također pokazujemo da električno polje, koje je povezano s površinskim valovima konačne amplitude, može primiti oblik anvelopnog solitona koji se širi duž granice plazma – vakuum brzinom koja ne ovisi o visini solitona