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This paper highlights unique sites in Ladakh, India, investigated during our 2016 multidisciplinary pathfinding expedition to the region. We summarize our scientific findings and the site's potential to support science exploration, testing of new technologies and science protocols within the framework of astrobiology research. Ladakh has several accessible, diverse, pristine and extreme environments at very high altitudes (3000–5700 m above sea level). These sites include glacial passes, sand dunes, hot springs and saline lake shorelines with periglacial features. We report geological observations and environmental characteristics (of astrobiological significance) along with the development of regolith-landform maps for cold high passes. The effects of the diurnal water cycle on salt deliquescence were studied using the ExoMars Mission instrument mockup: HabitAbility: Brines, Irradiance and Temperature (HABIT). It recorded the existence of an interaction between the diurnal water cycle in the atmosphere and salts in the soil (which can serve as habitable liquid water reservoirs). Life detection assays were also tested to establish the best protocols for biomass measurements in brines, periglacial ice-mud and permafrost melt water environments in the Tso-Kar region. This campaign helped confirm the relevance of clays and brines as interest targets of research on Mars for biomarker preservation and life detection.
In this paper, two different radiating structures fed with modified L-probe, are reported using a circuit theory concept. The proposed antennas are operating in wireless local area network (WLAN) and universal mobile telecommunications system (UMTS) frequency bands. In the first design, an E-shaped patch is studied to increase the bandwidth. It is observed that the bandwidth is directly proportional to notch dimensions. In the second design, E-shaped patch is modified to reduce the antenna size up to 30% with high bandwidth. In the first design, measured bandwidth and gain achieved are 32.68% (1.92–2.67 GHz) and 8.43 dBi while in second design it is 34.19% (1.94–2.74 GHz) and 8.39 dBi, respectively. Radiation patterns for both the antennas are symmetrical and broadside in nature. The proposed antennas are fabricated and measured results compare well with the theoretical and simulated results.
The bone regeneration and healing effect of formononetin was evaluated in a cortical bone defect model that predominantly heals by intramembranous ossification. For this study, female Balb/c mice were ovariectomised (OVx) and a drill-hole injury was generated in the midfemoral bones of all animals. Treatment with formononetin commenced the day after and continued for 21 d. Parathyroid hormone (PTH1–34) was used as a reference standard. Animals were killed at days 10 and 21. Femur bones were collected at the injury site for histomorphometry studies using microcomputed tomography (μCT) and confocal microscopy. RNA and protein were harvested from the region surrounding the drill-hole injury. For immunohistochemistry, 5 µm sections of decalcified femur bone adjoining the drill-hole site were cut. μCT analysis showed that formononetin promoted bone healing at days 10 and 21 and the healing effect observed was significantly better than in Ovx mice and equal to PTH treatment in many aspects. Formononetin also significantly enhanced bone regeneration as assessed by calcein-labelling studies. In addition, formononetin enhanced the expression of osteogenic markers at the injury site in a manner similar to PTH. Formononetin treatment also led to predominant runt-related transcription factor 2 and osteocalcin localisation at the injury site. These results support the potential of formononetin to be a bone-healing agent and are suggestive of its promising role in the fracture-repair process.
Balance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of β-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT’s rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/β-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.
With increasing interest in natural products of plant origin for medicinal and health care benefits there is added emphasis on the quality of the source raw material. In most cases the vegetative tissues and organs are the source of the required raw material. However, such tissues/organs may become infested/susceptible to many diseases causing deterioration of the quality of the desired economic product and loss of genetic resources. Considerable progress has been made with respect to the identification of disease causing organisms, and their pathogenic impact at organ, cellular and biochemical level. This review focuses on various diseases caused by bacteria, fungi, nematodes, viruses and phytoplasmas threatening the yield, biomass, bioactive potential of medicinal and aromatic plants of the sub-tropics. Several studies suggest that management of diseases through biological measures is more effective to check multiple diseases. Necessary management strategies for efficient disease management to realize quality raw material and enhanced metabolite productive potential have been outlined.
Genetic diversity of a red clover global collection was assessed using 36 simple sequence repeat (SSR) primers representing all seven linkage groups (LGs). The number of fragments amplified ranged from 1 to 6 for all the primers. Primer RCS0060 detected highest number of fragments, whereas four SSRs viz., RCS0899, RCS1594, TPSSR40 and RCS6927 amplified single fragment. Size range of amplicons generated by all the primers varied from 100 to 400 bp. Polymorphism information content values ranged from 0.301 to 0.719 with an average value of 0.605. LG wise diversity analysis showed that LG 3 was most diverse (I = 0.65, Ht = 0.44), whereas LG-1 showed minimum diversity (I = 0.48, Ht = 0.26) for the microsatellites used. Bayesian model-based clustering inferred three genetically distinct populations in the red clover germplasm holding and showed considerable admixture in individuals within clusters. Neighbour-joining analysis showed intermixing of accessions within groups. Principal component analysis plot complemented the clustering shown by Structure and distinguished three populations to greater extent. Analysis of molecular variance showed that 91% of the genetic variation was residing within populations, while 9% variation was among populations. Overall, the results showed that a high level of genetic diversity is prevailing in this worldwide collection of red clover, which can be exploited for its genetic improvement through breeding approaches.
The concept of stealth or radar cross section (RCS) reduction and control has been a topic of interest since World War II. Attempts were initially made to reduce the detectability of the aircraft by employing wood and other composites as aircraft materials since they were less reflective to the radar waves than a metal. Following the initial systematisation, one realised that shaping and coating [by radar-absorbing materials (RAMs)] emerged as the primary techniques for the RCS reduction (RCSR).
RCSR through shaping is readily apparent in case of stealth fighter aircraft F-22. The edges at principal and drooping ends of wings and rear end of the aircraft have similar angular sweep. Further, the fuselage and canopy are smooth-surfaced with slopes at sides. The shapes of the surface interfaces, such as the doors at bay and the seam of the canopy, are saw-wave-type. The vertical airfoil of aircraft tails is slant. The front side of its engine is obliterated and includes a serpentine-shaped engine duct. Finally, all the weapons are stored within the aircraft itself. These alterations in the conventional shape of the aircraft resulted in considerable RCSR of the aircraft.
In contrast, RAM coatings have been used since 1950s to achieve low-RCS aircraft design. RAM was also useful in mitigating the coupling effect and cross talk between the antennas mounted on the surface of the aircraft. The reconnaissance airplane Lockheed U-2 and the fighter aircraft F-117 are few examples where RAM has been used for RCSR.
Sufficient knowledge base was created over time regarding the scattering behaviour of aircraft structures. The parameters that played a significant role in overall scattering characteristics of these structures were identified. For example, flat plates and cavities were observed to result in large radar return at normal incidence. Similarly, the inlet and exhaust systems of the fighter aircraft were identified as significant contributors towards the aircraft RCS in front-on and rear-on angles, while its vertical tail dominated the radar signature from other angles at the sides.
Optimum array processors find applications in diverse areas as versatile sensors. They are used in radar and communication systems that are subject to various types of interference and jamming. The sidelobe cancellers mainly perform the function of separating an unwanted signal from the desired signal to extract the relevant information from the signal while simultaneously reducing the noise power level. Various schemes of cancellers being proposed and implemented have better interference suppression capabilities and faster convergence (Li and Stoica 2005). This interference suppression capability of sidelobe cancellers can be used towards active radar cross section reduction (RCSR). Moreover, the application of an efficient adaptive algorithm like least mean square (LMS) in sidelobe cancellers can reduce the implementation complexity. In other words, sidelobe cancellers implementing an appropriate algorithm for weight optimisation can effectively suppress correlated and uncorrelated interfering signals. These interfering signals can be narrowband sources with single frequency, i.e. zero bandwidth or broadband sources distributed over a spectral band with some finite bandwidth.
Generalised sidelobe canceller (GSC) is especially useful when the information regarding the direction of arrival (DOA) of the interfering signal is not available a priori. The GSC is quite effective in reducing the computational burden when used with proper weight adaptation algorithms. The GSC employs linearly constrained minimum variance (LCMV) criterion to suppress the hostile sources incident from different directions but at the same time retains high output signal-to-interference noise ratio (SINR) towards the sources looking from desired directions. However, the performance of the GSC degrades considerably in case of discrepancy between the calculated and actual DOA (Figure 7.1). Moreover, the input signal of GSC is included in the stochastic gradient. Thus, the gradient becomes big and requires small step-size for weight adaptation for achieving converged solution.
This reduces the speed of convergence and, hence, the response of array towards the signal environment.