413 research outputs found

    Experimental evidence for vibrational resonance and enhanced signal transmission in Chua's circuit

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    We consider a single Chua's circuit and a system of a unidirectionally coupled n-Chua's circuits driven by a biharmonic signal with two widely different frequencies \omega and \Omega, where \Omega >> \omega. We show experimental evidence for vibrational resonance in the single Chua's circuit and undamped signal propagation of a low-frequency signal in the system of n-coupled Chua's circuits where only the first circuit is driven by the biharmonic signal. In the single circuit, we illustrate the mechanism of vibrational resonance and the influence of the biharmonic signal parameters on the resonance. In the n(= 75)-coupled Chua's circuits enhanced propagation of low-frequency signal is found to occur for a wide range of values of the amplitude of the high-frequency input signal and coupling parameter. The response amplitude of the ith circuit increases with i and attains a saturation. Moreover, the unidirectional coupling is found to act as a low-pass filter.Comment: 15 pages, 12 figures, Accepted for Publication in International Journal of Bifurcation and Chao

    Characterization of uniform and hybrid cellular automata with null boundary

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    In this article, we dispute about the characterization of Cellular automata with restricted vertical neighborhood and Von neumann neighborhood of null boundary conditions over the field Z₂ in uniform cellular automata and hybrid cellular automata. Transition rule matrix for uniform and hybrid cellular automara with null boundary condition is obtained and the reversibility of the uniform cellular automata studied.Publisher's Versio

    Cultural Components in Karisal Region in the works of K.Ra

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    Among the literary personalities of Tamil language K. Ra (K.Rajanarayanan) has won a good place in people's minds through his works. K. Rajanarayanan lived in Karisal region created literary works based on the karisal region. He documented the traditions and cultural aspects of the Karisal land people through his works. He called himself as a vernacular artist and his works are very unique. This article explains about the beliefs, customs, rituals, weddings, festivals, worships and practices followed in the Karisal land and it expresses their culture

    Estimation of alkaloid content of Ashwagandha (Withania somnifera) with HPLC methods

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    Withania somnifera (Family; Solanaceae) is commonly known as Ashwagandha and is used in traditionally system of medicine since long time. Many compounds have been reported from the root part of the plant. In present study, comparative evaluation of microbial consortium and uninoculated control plant root collected from different geographically sources was done by HPLC. Methanol soluble root extract of the plant was subjected to Column chromatography to isolate and purify the phyto-constituents which can be termed as markers. Three compounds were isolated and purified. Compounds were characterized as withanone and withaferin-A. The third compound was found to be impure. Novel HPLC methods were developed for assessment of purity, for standardization and for estimation of the compounds. Simplicity of isolation and HPLC analysis for the compounds suggests that the compounds may be termed as markers for the standardization of the methanol extracts and preparations containing Withania somnifera

    Effect of microbial consortium on plant growth and improvement of alkaloid content in Withania somnifera (Ashwagandha)

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    The effect of microbial consortium consisting Plant Growth Promoting Rhizobacteria (PGPR) like Azospirillum, Azotobacter, Pseudomonas and Bacillus were tested separately and in combination on Withania somnifera for two consecutive years (2009 and 2010). The combinations of above mentioned PGPR strains significantly increased plant height, root length, and alkaloid content in Withania somnifera when compared to the uninoculated control. Plant growth promoting rhizobacteria (PGPR) exhibit direct and indirect mechanisms as plant growth promoters and biological control agents. Direct mechanism by PGPR, include the provision of bio-available phosphorus for plant uptake, nitrogen fixation for plant. The results of this study suggest that the PGPR applied in combination have the potential to increase the plant growth, alkaloid content of Withania somnifera

    Design and Performance Validation of Vapour Absorption Solar Air Conditioning System

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    The Solar based absorption systems are used for the reduction of power load that is caused because of the utilization of the compressors. There have been different absorption sets that are tried for space cooling applications by bringing in different solar based heat inputs. The NH3 � H2O based absorption system need a working temperature of 120�C to 150�C, and requires concentrators with tracking and attracting higher qualities, however NH3 � H2O vapour absorption systems can operate at lower temperatures and can utilize FPC or ETC solar water heating frameworks as generators. In the near future, this will bring in low cost and low maintenance. The single effect 1 KW, NH3 � H2O absorption system with evacuated tube solar collector is attempted in this research work. The testing of the system and comparison of COPs with standard vapour absorption Solar Air Conditioning system are done

    A Comparative study of 150μg of Buprenorphine with 0.3% Bupivacaine and 0.3% Bupivacaine alone in Brachial Plexus Block by Low Interscalene Approach in Upper Limb Surgeries

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    INTRODUCTION: Regional Anaesthesia is the blocking of peripheral nerve conduction in a reversible way by using local anesthetic agents, thereby one region of the body is made insensitive to pain and is devoid of reflex response to surgical stimuli. In this the CNS is spared, so that the patient is conscious, fully aware during the surgical procedure without recognizing pain. Regional Anaesthesia has many advantages over general anaesthesia for surgeries on upper extremities particularly in emergency surgeries. They are: (i) Proven to be the safest anaesthesia for high risk patients who are in greater risk due to stress imposed by general anaesthesia. (ii) Only method of anaesthesia which prevents all afferent impulses from the site of surgery reaching the CNS. Hence the need of poly pharmacy and its side effects are eliminated. (iii) Along with complete pain relief and total muscle relaxation it produces vasodilatation, which improve blood circulation, and prevents tissue hypoxia. (iv) Causes least disturbance to the normal physiology than any other type of anaesthesia. (v) Postoperative pain relief is ensured for a longer duration by using long acting anaesthetic drug and for several days if continuous block using catheter technique is employed. (vi) Many intra operative, postoperative complication of general anaesthesia are avoided. (vii) It is cost effective and safe. (viii) Avoids theatre pollution. (ix) Safest technique for patients with full stomach. The use of pneumatic tourniquet provides a bloodless field during upper extremity surgeries. The tourniquet pain is a concern because of the technical difficulty to block individual nerves. Brachial plexus block by supraclavicular approach is the solution in such a situation. There are different approaches for blocking brachial plexus, the common approaches are (a) Supraclavicular approach, (b) Interscalene approach, (c) Axillary approach, Axillary approach has the lowest incidence of serious complication and can be performed with ease. Still there is limitation associated with axillary approach like, • It is inadequate for operation on the arm and shoulder. • It is difficult to block the musculocutaneous nerve predictably with resultant sparing of the radial aspect of forearm and dorsum of hand. • Tourniquet pain is not well tolerated. • Also abducting the arm by 90° for giving the block may be painful and even dangerous in traumatic lesions of the upper extremities. Hence the brachial plexus block by low scalene approach is the method of choice for upper limb surgeries. In 1970 Alon Winne first demonstered interscalene approach of brachial block. William Steward Halsted first performed brachial plexus block in 1885. In 1911 Kulenkampff and Hirschel described the first percutanceous brachial plexus block by supraclavicular and axillary routes respectively. Since then several techniques have been used to prolong the brachial plexus block. • Continues infusion of local anaesthetic through catheters. • Addition of epinephrine and α2 agonist like clonidine. • Addition of opioids are being used as adjuvant to local anaesthetic solution e.g. Morphine, Buprenorphine and butorphanol. Buprenorphine, a thebaine derivative of semi synthetic opioid compound acts both on muopioids receptor and Kappa receptors. It is used for pain relief and this is given by intra muscular, intra venous, epidural and spinal routes and the dose in 0.3 to 0.6mg. It is many times more potent than morphine and it has side effects of nausea, vomiting, respiratory depression etc. This study compares the effects of addition of Buprenorphine to local anaethetic solution with plain local anaesthetic solution for brachial plexus block, with regard to onset, time for total blockade, duration and quality of blockade. AIM OF STUDY: The opioid receptors are found in the central nervous system. The presence of these receptors in the somatic and sympathetic peripheral nerves has also been documented. In this study an alternate is made to compare the effects of addition of buprenorphine to 0.3% bupivacaine versus 0.3% bupivacaine, and also to evaluate the action of buprenorphine on the peripheral nerve receptors in brachial plexus block. So, this is the study to 1. To compare the effects and actions of 0.3% bupivacaine and addition of 150μg buprenorphine to 0.3% bupivaccine in brachial plexus block by low interscalene approach. 2. To compare the onset, time taken for total blockade, duration and intensity of motor and sensory blockade. 3. To evaluate the action of opioid, buprenorphine on the peripheral nerves. MATERIAL AND METHODOLOGY: Forty adult patients of both sexes in the age group of 18 to 58 belonging to ASA I/II attending the Plastic & hand reconstructive surgery department at Stanley Medical College Hospital, Chennai-1 formed the material for the study. They were randomly divided into 2 groups I and II. Group I - 20 patients received 30 ml of 0.3% bupivacaine plus 1ml of isotonic sodium chloride solution making the solution 0.3%. Group II - 20 patients received 18ml of 0.5% bupivacaine plus 1ml of 150 microgram of buprenorphine. Patient selection: 1. Only ASA I & ASA II were included. 2. Age group between 18 to 58 years. 3. Weight between 40 to 70kg. 4. Both emergency and elective procedure involving the upper limb were included. 5. Both in patients and outpatients were included. Exclusion criteria: 1. Patient refusal, 2. Clinically significant coagulopathy bacterial, fungal infection the injection site, 3. Pneumothorax, 4. Known epileptic. SUMMARY: 1. Onset time of sensory and motor blockade is shorter in Group II than control Group I. 2. There was no difference in the time for total sensory and motor blockade in both the groups. 3. These was significant increase in the duration of blockade in the Group II than Group I. 4. There was significant increase in the intensity of sensory and motor blockade in the Group II than Group I. 5. There was no complication due to addition of 150 micrograms of buprenorphine to 0.3% bupivacaine. CONCLUSION: We conclude that in brachial plexus block by low interscalne approach, the addition of 150μg of buprenorphine with 0.3% bupivacaine provides intense, prolonged sensory and motor blockade without complication when it is compared to the block produced by plain 0.3% of bupivacaine solution alone

    Larvicidal and repellent activity of tetradecanoic acid against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say.) (Diptera:Culicidae)

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    AbstractObjectiveTo investigate the larvicidal and repellent efficacy of tetradecanoic acid against Aedes aegypti (Ae. aegypti) L. and Culex quinquefasciatus (Cx. quinquefasciatus) Say (Diptera: Culicidae).MethodsLarvicidal efficacy of tetradecanoic acid was tested at various concentrations against the early third instar larvae of Ae. aegypti and Cx. quinquefasciatus. The repellent activity was determined against two mosquito species at three concentrations viz., 1.0,2.5 and 5.0 ppm under the laboratory conditions.ResultsThe tetradecanoic acid was found to be more effective against Cx. quinquefasciatus than Ae. aegypti larvae. The LC50 values were 14.08 ppm and 25.10 ppm, respectively. Tetradecanoic acid showed lesser repellency against Ae. aegypti and Cx. quinquefasciatus. The highest repellency was observed in higher concentration of 5.0 mg/cm2 provided 100% protection up to 60 and 90 min against Ae. aegypti and Cx. quinquefasciatus respectively.ConclusionsFrom the results it can be concluded the tetradecanoic acid is a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes

    Analysis of Antioxidant Enzyme activity in various genotypes of Helianthus annuus L. (Sunflower) under varied irrigation regimes

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    In this investigation, a pot culture experiment was conducted to estimate the effect of drought stress of Helianthus annuus L. (Sunflower). Sunflower is one of the most important oil crop and due to its high content of unsaturated fatty acids, a lack of cholesterol and the oil benefits from a desirable quality. Plant growth and productivity is adversely affected by nature’s wrath in the form of various biotic and abiotic stress factors. Water deficit is one of the major abiotic stresses, which   adversely affects crop growth and yield. The present study was aimed to understand the effects of drought stress on antioxidant enzymes like peroxidase, superoxide dismutase, catalase and ascorbate peroxidase activity on five different cultivars (SH 3322, A-110, K-618, SH 416, and S-275) of sunflower. All the sunflower cultivars showed reduced growth and altered enzymes activities under drought conditions. The antioxidant enzymes activities were increased under drought stress in all parts of the sunflower cultivars. The maximum activity was observed in K-618 and the minimum in S-275 cultivar. Among the five cultivars studied, K-618 showed better tolerance capacity in pot culture conditions under drought stress when compared to other cultivars studied.    Â