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Comparative anatomical features of Prosopis cineraria (L.) Druce and Prosopis juliflora (Sw.) DC (Mimosaceae)
Robertson Stellaa,Narayanan N,Deattu N,Ravi Nargis N
International Journal of Green Pharmacy , 2010,
Abstract: A comparative study of the leaflets of two domestic species of Prosopis is reported. Both the species, Prosopis cineraria and Prosopis juliflora, have been reported to possess antibacterial, antifungal, anti-inflammatory and the most concerning anticancer properties. In view of its medicinal importance and taxonomic confusion, the individual morphological and histological characteristics of these two species have been described through certain parameters such as structural profile of the leaflets, stomatal morphology, venation pattern, petiolule and vascular system of the rachis. Evaluation of the fresh and anatomical sections of the leaves of both species was carried out to determine its macro- and microscopical (histological) characters. The studies indicated the presence of bipinnately compound leaf, an entire margin, apiculate apex, obtuse base, reticulate venation, thick and straight anticlinal walled epidermal cells, prismatic type of calcium oxalate crystals in the mesophyll tissue, dense deposition of tannin content and paracytic type stomata in the P. cineraria, whereas P. juliflora has a bipinnately compound leaf with an entire margin, blunt apex, round base, reticulate venation, thick and straight walled epidermal cells, large mucilage cavities in the mesophyll tissue and paracytic type stomata. The above findings provided referential information for identification of the species P. cineraria and P. juliflora.
Effects of Parasitism on the Development and Food Consumption of Larva of Spilosoma obliqua (Walker) by its Parasitoid Apanteles obliquae Wilkinson
Nargis Sultana
Journal of Biological Sciences , 2003,
Abstract: The effects of parasitism of braconid wasp, Apanteles obliquae Wilkinson (Hymenoptera: Braconidae) on the developmental stages and food consumption of larva of Spilosoma obliqua (Walker) were studied in the laboratory. The differences in growth and development of host larvae were marked with regard to ecdysis (moult) and size in parasitised larvae. The reduction in host size due to parasitism was observed in parasitised larvae. S. obliqua larvae that were parasitised consumed significantly less leaf area than the non-parasitised larvae. The greater portion (96.95 sq.cm. of jute leaf) of feeding by non-parasitised larva occurred after the host larva reached the 5th instar stage, whereas feeding by parasitised larva of same age remained at low level (32.54 sq.cm. of jute leaf). Results indicated that larva parasitised at 3rd instar stage cause considerably less damage (one third of healthy larva) to the host plant than non- parasitised larva.
Exergy Analysis of Porous Medium Combustion Engine Cycle
N. Ravi Kumar
ISRN Mechanical Engineering , 2011, DOI: 10.5402/2011/542840
Abstract: The need of the fossil fuels is ever increasing in the areas of manufacturing, transportation, heating, and electricity. Nearly 90% of the energy requirement in transport sector is met by combustion of fossil fuels only. Porous media (PM) combustion is an effective method, which can increase the combustion efficiency as well as minimize environmental pollution. The present paper is aimed at thermodynamic analysis of ideal IC engine cycles with porous media combustion. Two practically possible cycles, namely, periodic and permanent contact of gas with porous medium are considered, and the ideal cycle analyses are made. It is found that PM engine with periodic contact is more efficient than permanent contact type. The exergy analysis also reveals that the energy loss due to irreversibilities in the periodic contact type is less than that of the permanent contact type. With the help of model calculations and graphs, the performance of these two cycles is compared and optimal operating conditions are also evaluated and presented along with the suggestions for enhancing the performance of homogeneous PM combustion in IC engines. 1. Introduction Combustion is one of the oldest technologies of mankind. It has been used for more than one million years for different purposes. At present, about ninety percent worldwide energy demand is met by combustion of fuels derived from depletion fossil fuel reserves. To cope up with the impending fuel crisis due to the increasing demand and depleting fossil fuel reserves, there is a need to further improve the performance of existing combustion systems and also to reduce the emissions levels to meet the emission norms. Porous medium combustion (PMC) is one such technology that has many advantages over the existing combustion systems. The steadily increasing use of fossil fuel has threatened the sustainability of life on the earth, since combustion of fossil fuel leads to increase in the emission levels in the atmosphere. Hence, to reduce the pollution level, there is always a demand for development and use of modern efficient technology for combustion of fossil fuel. In recent times, many researchers have developed several newer methods for efficient combustion of fossil fuel. Durst and Weclas [1] established that porous media combustion (PMC) is one such effective method, which can increase the system efficiency as well as minimize environmental pollution. This technology is entirely different from conventional combustion, which is characterized by a free flame, thin reaction zone, and high temperature gradients. It has
Manipulation of Costimulatory Molecules by Intracellular Pathogens: Veni, Vidi, Vici!!
Nargis Khan equal contributor,Uthaman Gowthaman equal contributor,Susanta Pahari,Javed N. Agrewala
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002676
Abstract: Some of the most successful pathogens of human, such as Mycobacterium tuberculosis (Mtb), HIV, and Leishmania donovani not only establish chronic infections but also remain a grave global threat. These pathogens have developed innovative strategies to evade immune responses such as antigenic shift and drift, interference with antigen processing/presentation, subversion of phagocytosis, induction of immune regulatory pathways, and manipulation of the costimulatory molecules. Costimulatory molecules expressed on the surface of various cells play a decisive role in the initiation and sustenance of immunity. Exploitation of the “code of conduct” of costimulation pathways provides evolutionary incentive to the pathogens and thereby abates the functioning of the immune system. Here we review how Mtb, HIV, Leishmania sp., and other pathogens manipulate costimulatory molecules to establish chronic infection. Impairment by pathogens in the signaling events delivered by costimulatory molecules may be responsible for defective T-cell responses; consequently organisms grow unhindered in the host cells. This review summarizes the convergent devices that pathogens employ to tune and tame the immune system using costimulatory molecules. Studying host-pathogen interaction in context with costimulatory signals may unveil the molecular mechanism that will help in understanding the survival/death of the pathogens. We emphasize that the very same pathways can potentially be exploited to develop immunotherapeutic strategies to eliminate intracellular pathogens.
A New Approach to find Total Float time and Critical Path in a fuzzy Project Network
V. Sireesha,N. Ravi Shankar
International Journal of Engineering Science and Technology , 2010,
Abstract: The purpose of the critical path method (CPM) is to identify the critical activities in the critical path of an activity network. In the real world for many projects we have to use human judgment for estimating the duration of activities. However, the unknowns or vagueness about the time duration for activities in network planning, has led to the development of fuzzy CPM. A way to deal with this imprecise data is to employ the concept of fuzziness, where the vague activity times can be represented by fuzzy sets. In this paper a new method based on fuzzy theory is developed to solve the project scheduling problem under fuzzy environment. Assuming that the duration of activities are triangular fuzzy numbers, in this method we compute total float time of each activity and fuzzy criticalpath without computing forward and backward pass calculations. Through a numerical example, calculation steps in this method and the results are illustrated. Compare with other fuzzy critical method the proposed method is simple, fast and effective to find total float time of each activity and fuzzy critical path in a fuzzy project network.
Discussing large dams in Asia after the World Commission on Dams: Is a political ecology approach the way forward?
Ravi Baghel,Marcus Nüsser
Water Alternatives , 2010,
Abstract: The guidelines proposed in the World Commission on Dams (WCD) final report were vehemently rejected by several Asian governments, and dam building has continued apace in most Asian countries. This reaction is in line with the simplistic dam debate, where dam critics offer laundry lists of socioeconomic and environmental costs, and dam proponents highlight the benefits while underestimating associated costs. Whereas the WCD sought to evaluate dams in terms of 'costs and benefits', this approach is self-defeating due to the very subjectivity of such measurements. This paper argues that the way ahead must be to move beyond a consensus evaluation of dams, and instead examine the shifting asymmetries and discursive flows that sustain and promote dam building over time. However, such an analysis of the dam discourse must incorporate an understanding of the multiple actors and driving forces, as well as the underlying power relations within this politicised environment. We therefore suggest that a post-structural political ecology approach provides a suitable framework for the future examination of large dams in Asia.
No Parity Violation without R Parity Violation
Ravi Kuchimanchi,R. N. Mohapatra
Physics , 1993, DOI: 10.1103/PhysRevD.48.4352
Abstract: In a class of supersymmetric left-right models (SUSYLR) of weak interactions where R-parity is automatically conserved, we show that spontaneous breakdown of parity CANNOT occur without spontaneous breakdown of R-parity. This intriguing result connects two physically different scales in supersymmetric models.
Circular orbit spacecraft control at the L4 point using Lyapunov functions
Rachana Agrawal,Ravi N Banavar
Physics , 2015,
Abstract: The objective of this work is to demonstrate the utility of Lyapunov functions in control synthesis for the purpose of maintaining and stabilizing a spacecraft in a circular orbit around the L4 point in the circular restricted three body problem (CRTBP). Incorporating the requirements of a fixed radius orbit and a desired angular momentum, a Lyapunov function is constructed and the requisite analysis is performed to obtain a controller. Asymptotic stability is proved in a defined region around the L4 point using LaSalle's principle.
A novel super resolution reconstruction of low reoslution images progressively using dct and zonal filter based denoising
Liyakathunisa,C. N . Ravi Kumar
Computer Science , 2011,
Abstract: Due to the factors like processing power limitations and channel capabilities images are often down sampled and transmitted at low bit rates resulting in a low resolution compressed image. High resolution images can be reconstructed from several blurred, noisy and down sampled low resolution images using a computational process know as super resolution reconstruction. Super-resolution is the process of combining multiple aliased low-quality images to produce a high resolution, high-quality image. The problem of recovering a high resolution image progressively from a sequence of low resolution compressed images is considered. In this paper we propose a novel DCT based progressive image display algorithm by stressing on the encoding and decoding process. At the encoder we consider a set of low resolution images which are corrupted by additive white Gaussian noise and motion blur. The low resolution images are compressed using 8 by 8 blocks DCT and noise is filtered using our proposed novel zonal filter. Multiframe fusion is performed in order to obtain a single noise free image. At the decoder the image is reconstructed progressively by transmitting the coarser image first followed by the detail image. And finally a super resolution image is reconstructed by applying our proposed novel adaptive interpolation technique. We have performed both objective and subjective analysis of the reconstructed image, and the resultant image has better super resolution factor, and a higher ISNR and PSNR. A comparative study done with Iterative Back Projection (IBP) and Projection on to Convex Sets (POCS),Papoulis Grechberg, FFT based Super resolution Reconstruction shows that our method has out performed the previous contributions.
Geometric approach to tracking and stabilization for a spherical robot actuated by internal rotors
Sneha Gajbhiye,Ravi N. Banavar
Computer Science , 2015,
Abstract: The paper adopts a geometric approach to stabilization and tracking of a spherical robot actuated by three internal rotors mounted on three mutually orthogonal axes inside the robot. The system is underactuated and subject to nonholonomic constraints. Initially, the equations of motion are derived through Euler-Poincar\'{e} reduction. Then two feedback control laws are synthesized: the first control law addresses orientation of the robot alone, keeping the contact point arbitrary; the second control law is a tracking law that addresses the contact position and angular velocity tracking.
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