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The community composition of zooplankton with an emphasis on copepods was assessed in the frontal zones of the Indian sector of the Southern Ocean (SO) during summer 2013. Copepods were the dominant group in both the bongo net and multiple plankton sampler across the entire region. High zooplankton abundance was recorded along each transect in the Polar Front (PF). Community structure in this front was dominated by common taxa, including Ctenocalanus citer, Clausocalanus spp., Calanoides acutus, Calanus propinquus, Calanus australis and Rhincalanus gigas, which together accounted for > 62% of the total abundance. Calocalanus spp., Neocalanus tonsus and C. propinquus were indicator species in the Sub-Tropical Front (STF), Sub-Antarctic Front and PF, respectively. A strong contrast in population structure and biovolume was observed between then PF and the STF. The community structure of smaller copepods was associated with the high-temperature region, whereas communities of larger copepods were associated with the low-temperature region. Thus, it seems probable that physical and biological characteristics of the SO frontal regions are controlling the abundance and distribution of zooplankton community structure by restricting some species to the warmer stratified zones and some species to the well-mixed zone.
For the first time in the literature, experimental determination of entire sets of exact interdiffusion coefficients in quaternary and quinary alloy systems is reported. Using the method of body-diagonal diffusion couple, a set of nine quaternary interdiffusion coefficients were evaluated in Fe–Ni–Co–Cr and a set of sixteen quinary interdiffusion coefficients were determined in a Fe–Ni–Co–Cr–Mn system, both at approximately equimolar compositions. Regions of uphill interdiffusion and zero flux planes were observed for nickel and cobalt in quinary couples, indicating the existence of strong diffusional interactions in Fe–Ni–Co–Cr–Mn alloys. The strong diffusional interactions were also manifested in the large magnitudes of cross coefficients in both the systems. The existence of strong diffusional interactions in high-entropy alloys (HEAs) as observed through experimentally determined interdiffusion coefficients in this study establishes beyond doubt the fact that cross interdiffusion coefficients cannot be ignored in HEAs.
While the burden of dementia is increasing in low- and middle-income countries, there is a low rate of diagnosis and paucity of research in these regions. A major challenge to study dementia is the limited availability of standardised diagnostic tools for use in populations with linguistic and educational diversity. The objectives of the study were to develop a standardised and comprehensive neurocognitive test battery to diagnose dementia and mild cognitive impairment (MCI) due to varied etiologies, across different languages and educational levels in India, to facilitate research efforts in diverse settings.
A multidisciplinary expert group formed by Indian Council of Medical Research (ICMR) collaborated towards adapting and validating a neurocognitive test battery, that is, the ICMR Neurocognitive Tool Box (ICMR-NCTB) in five Indian languages (Hindi, Bengali, Telugu, Kannada, and Malayalam), for illiterates and literates, to standardise diagnosis of dementia and MCI in India.
Following a review of existing international and national efforts at standardising dementia diagnosis, the ICMR-NCTB was developed and adapted to the Indian setting of sociolinguistic diversity. The battery consisted of tests of cognition, behaviour, and functional activities. A uniform protocol for diagnosis of normal cognition, MCI, and dementia due to neurodegenerative diseases and stroke was followed in six centres. A systematic plan for validating the ICMR-NCTB and establishing cut-off values in a diverse multicentric cohort was developed.
A key outcome was the development of a comprehensive diagnostic tool for diagnosis of dementia and MCI due to varied etiologies, in the diverse socio-demographic setting of India.
This paper dwells upon investigating the effect of aspect ratio (AR) variation on the aerodynamic performance of unconventional control surfaces called grid fins by virtue of a series of subsonic experiments on a simplified grid fin variant called the cascade fin. Wind tunnel tests were performed for different AR (variable span) grid fins. The same had been investigated for different gap-to-chord ratio (g/c) variants. Results demonstrated a tangible increase in the aerodynamic efficiency as well as stall angle reduction for higher AR. Moreover, higher AR leads to increased pitching moment, which emphasizes elevated hinge moment requirements. The study ensued the presence of higher deviation between the low AR fins, that is
compared to the pertinent deviations between the high AR fins, that is
. The effect associated with these variations was termed as span effect in this paper. It was established that, the deviations arising due to this phenomena were lesser for higher g/c and higher AR. The analysis of AR variation for different g/c presented a limiting value of AR reduction for stall performance enhancement. Thus, optimised selection of the g/c and AR values can lead to enhanced aerodynamic efficiency alongside an improved stalling characteristic.
Cerebral malaria (CM) is the severe neurological complication causing acute non-traumatic encephalopathy in tropical countries. The mechanisms underlying the fatal cerebral complications are still not fully understood. Glutamate, a major excitatory neurotransmitter in the central nervous system of the mammalian brain, plays a key role in the development of neuronal cells, motor function, synaptic plasticity, learning and memory processes under normal physiological conditions. The subtypes of ionotropic glutamate receptor are N-methyl-D-aspartate receptors (NMDARs) which are involved in cellular mechanisms of learning and memory, synaptic plasticity and also mediate excitotoxic neuronal injury. In the present study, we found that glutamate level in synaptosomes, as well as expression of NMDAR, was elevated during the extreme condition of CM in C57BL6 mice. Arteether at 50 mg kg−1 × 1, 25 mg kg−1 × 2, days decreased the NMDAR expression and increased the overall survival of the experimental CM mice.
The present study investigated if the presence of encircling granulosa cells protected against di(2-ethylhexyl)phthalate (DEHP)-induced oxidative stress in rat oocytes cultured in vitro. Denuded oocytes and cumulus–oocyte complexes (COCs) were treated with or without various doses of DEHP (0.0, 25.0, 50.0, 100, 200, 400 and 800 μM) in vitro. Morphological apoptotic changes, levels of oxidative stress and reactive oxygen species (ROS), mitochondrial membrane potential, and expression levels of apoptotic markers (Bcl2, Bax, cytochrome c) were analyzed. Our results showed that DEHP induced morphological apoptotic changes in a dose-dependent manner in denuded oocytes cultured in vitro. The effective dose of DEHP (400 µg) significantly (P>0.05) increased oxidative stress by elevating ROS levels and the mitochondrial membrane potential with higher mRNA expression and protein levels of apoptotic markers (Bax, cytochrome c). Encircling granulosa cells protected oocytes from DEHP-induced morphological changes, increased oxidative stress and ROS levels, as well as increased expression of apoptotic markers. Taken together our data suggested that encircling granulosa cells protected oocytes against DEHP-induced apoptosis and that the presence of granulosa cells could act positively towards the survival of oocytes under in vitro culture conditions and may be helpful during assisted reproductive technique programmes.
Particle-in-cell (PIC) and Vlasov simulations both solve the Vlasov equation. The Vlasov equation (cf. Chapter 2) governs the evolution of the distribution function of charged particles (electrons, ions) in the six-dimensional phase space, consisting of three velocity (or momentum) dimensions and three position dimensions, plus time. It offers an accurate description of a plasma in the collisionless limit; that is, when the particles are affected by long-range electric and magnetic fields only, and when short-range fields from their nearest neighbors can be neglected.
PIC simulations resolve the distribution function statistically with macro-particles (or super-particles) and follows the solution over trajectories along which the distribution function is constant; the characteristics are given by the equations of motion for the charged particles. This is the Lagrangian description. Many PIC codes have been developed over the years; modern PIC codes include the plasma simulation code (PSC) originally developed by Hartmut Ruhl, the implicit iPIC3D code aimed at connecting kinetic and magnetohydrodynamic time scales, the EPOCH code, partially based on PSC, the VSIM/VORPAL code, the OSIRIS code, and QuickPIC. PIC simulations are very adaptive and efficient for many problems, such as high-energy beam–plasma and laser–plasma interactions. On the other hand, they also have limitations; the numerical noise and slow convergence with increasing number of particles are some issues. There is also the need to resolve the Debye length with particles to avoid artificial numerical heating.
A different strategy is followed in Vlasov simulations using a Eulerian description. Here, the distribution function is treated as a phase fluid resolved on a fixed numerical grid. Vlasov simulations do not have the statistical noise of PIC simulations; they can also more accurately resolve the high-velocity tail of the particle distribution functions. On the other hand, Vlasov simulations in higher dimensions are very memory demanding due to the need to resolve the six-dimensional phase space on a numerical grid. In some cases, the distribution function can also become oscillatory in phase space, leading to sharp gradients and a need to introduce numerical dissipation in velocity space whilst avoiding artificial numerical heating due to the broadening of the distribution in velocity space. Hence, the choice between PIC and Eulerian Vlasov simulations strongly depends on the physical problem at hand.
The laser, with its coherent, monochromatic, and well collimated character, has been a most remarkable discovery of the twentieth century. Along with semiconductors, its multifaceted applications have broadly touched and greatly improved our lives – it has made an indelible mark in the field of sensing, printing, barcode scanning, surgery, communications, and so on. It has also become a major tool for scientific research. For example, Thomson scattering and laser induced fluorescence are important tools for plasma diagnostics. Lasers have been used successfully for cooling of atoms and heating of plasmas.
The laser peak power has increased about a 1000 fold every decade since its invention. Starting from hundred watts in the 1960s, table top terawatt Ti: sapphire lasers became available in the 1990s following the discovery of the chirped pulse amplification (CPA) by Mourou and Strickland in 1985. These lasers do not only have high power but also very short pulses of a few femtoseconds, opening a new field of ultra-short pulse lasers and their interactions with matter, such as electron dynamics in molecules. In the past few years, we have seen worldwide efforts to build high power laser infrastructures. The Extreme Light Infrastructure (ELI) has been approved to construct three petawat laser facilities in Eastern Europe. Similar efforts are being made in Korea, Japan and China.
With the rise in laser power, there has been a phenomenal growth in the field of high power laser-plasma interaction with diverse applications, ranging from laser driven fusion and laser acceleration of charged particles to laser ablation of materials. The field has revealed a rich variety of fascinating new phenomena. Parametric coupling between lasers and plasma eigenmodes and quasi-modes gives rise to stimulated Raman, Brillouin, and Compton scattering, two-plasmon decay, and four-wave processes of filamentation, modulational, and oscillating two-stream instabilities of the laser. Nonlinear refraction gives rise to selffocusing and self-guiding of lasers over long distances in plasma and air, offsetting diffraction divergence. Laser interaction with rough metallic surfaces reveals surface-enhanced Raman scattering (SERS) where Raman scattered power from adsorbed molecules rises a million times due to surface plasmon resonance. Laser mode conversion to surface plasma waves (SPWs) on metallic surfaces has been shown to enhance the ablation yield and thin film deposition rates by orders of magnitude, making pulsed laser deposition a very attractive scheme.