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Search Results: 1 - 10 of 7371 matches for " Das "
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In Vitro Somatic Embryogenesis in Some Oil Yielding Tropical Tree Species  [PDF]
Premananda Das
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.22023
Abstract: Somatic embryogenesis was achieved in two oil yielding tropical tree species i.e. Simarouba glauca & Azadirachta indica using immature zygotic embryos as explants on Murashige and Skoog (MS) medium supplemented with 0.5 – 1.5 mg/l benzylaminopurine (BA) and 2.0 - 3.0 mg/l NAA (1-napthaleneacetic acid) or 2, 4-D (2,4-dichlorophenoxyacetic acid) and 3% sucrose. MS medium containing 1.0 mg/l BA and 2.0 mg/l NAA was noted to be the most effective in inducing friable embryogenic callus (FEC) in Simarouba glauca; the number of somatic embryos per culture varied in MS medium supplemented with 1.0 – 1.5 mg/l BA and 1.0 mg/l NAA. In Azadirachta indica, somatic embryos developed on MS medium supplemented with 0.5 mg/l BA and 1.5 – 2.0 mg/l 2,4-D which were in various shapes and sizes after the first subculture on MS medium supplemented with 0.25 mg/l abscisic acid. The somatic embryos which developed shoots were isolated and rooted in 1/2 strength MS medium supplemented with 0.25 mg/l abscisic acid and 2% sucrose. About 25% of embryos germinated within 20 days of culture in case of Simarouba glauca and 62% in Azadirachta indica. The somatic embryo-derived plantlets were transferred to the field after being hardened in the climate controlled hardening chamber.
Besicovitch-Eggleston Function  [PDF]
Manav Das
Advances in Pure Mathematics (APM) , 2011, DOI: 10.4236/apm.2011.15048
Abstract: In this work we introduce a function based on the well-known Besicovitch-Eggleston sets, and prove that the Hausdorff dimension of its graph is 2.
Quantized Energy Momentum and Wave for an Electromagnetic Pulse—A Single Photon inside Negative Refractive Indexed Media  [PDF]
Shantanu Das
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.212183
Abstract: An Electromagnetic (EM) radiation in dispersion less free space vacuum is represented by a photon, with corpuscular and wave nature. The discussions, for the past century aimed at the nature of photon inside a media having dispersion in the refraction property, other than free space. What about its nature if the space be of refractive index which is negative, is discussed in this paper. We call mechanical momentum, wave-momentum, and try to match our present theories with intriguing property of this ‘photon’ or pulse carrying EM energy packet, and more so we try to find its property energy, momentum inside a media a positive refractive media, and if the media show a negative refractive index behavior, then these queries are profound, and suitable explanations to these classical concepts of corpuscular-wave nature of photon inside these media are quest for the scientists dealing with these materials having negative index of refraction. Here some of this counterintuitive nature of corpuscular-wave nature of photon inside negative indexed material is brought out, with possible ‘new definition’ of its ‘wave-momentum’, the concept of ‘reactive energy’ inside negative indexed material, along with possible ‘new wave equation’. These definitions and expressions of ‘wave-momentum’ and ‘reactive energy’ pertaining to negative indexed material are new and discussed and derived by classical means.
Is There Chaos in Inflation Data?  [PDF]
Pritha Das
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.25026
Abstract: Economic indicators are snippets of financial and economic data published regularly by governmental agencies and the private sector. An exchange rate represents the value of one currency in another and it fluctuates over time. ForEx rates are affected by many highly correlated economic, political and even psychological factors. It was observed that changes in the exchange rate are related to news in the fundamentals which cover Inflation for the country concerned. In a series of work, we investigated and confirmed the chaotic property of ForEx Rates of several countries. In this perspective, we concentrate on nonlinear data analysis of inflation data of nine countries. We find existence of chaos in inflation data for some countries.
Revisiting the Curie-Von Schweidler Law for Dielectric Relaxation and Derivation of Distribution Function for Relaxation Rates as Zipf’s Power Law and Manifestation of Fractional Differential Equation for Capacitor  [PDF]
Shantanu Das
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.812120
Abstract: The classical power law relaxation, i.e. relaxation of current with inverse of power of time for a step-voltage excitation to dielectric—as popularly known as Curie-von Schweidler law is empirically derived and is observed in several relaxation experiments on various dielectrics studies since late 19th Century. This relaxation law is also regarded as “universal-law” for dielectric relaxations; and is also termed as power law. This empirical Curie-von Schewidler relaxation law is then used to derive fractional differential equations describing constituent expression for capacitor. In this paper, we give simple mathematical treatment to derive the distribution of relaxation rates of this Curie-von Schweidler law, and show that the relaxation rate follows Zipf’s power law distribution. We also show the method developed here give Zipfian power law distribution for relaxing time constants. Then we will show however mathematically correct this may be, but physical interpretation from the obtained time constants distribution are contradictory to the Zipfian rate relaxation distribution. In this paper, we develop possible explanation that as to why Zipfian distribution of relaxation rates appears for Curie-von Schweidler Law, and relate this law to time variant rate of relaxation. In this paper, we derive appearance of fractional derivative while using Zipfian power law distribution that gives notion of scale dependent relaxation rate function for Curie-von Schweidler relaxation phenomena. This paper gives analytical approach to get insight of a non-Debye relaxation and gives a new treatment to especially much used empirical Curie-von Schweidler (universal) relaxation law.
Combustion and Ball Milled Synthesis of Rare Earth Nano-Sized Ceria Powder  [PDF]
Ranjan Sen, Siddhartha Das, Karabi Das
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.25054
Abstract: This paper reports a study on nanocrystalline ceria powder prepared by high energy ball-milling and combustion synthesis methods. The combustion synthesis was carried out using ceric ammonium nitrate as oxidizer and citric acid, glycine or citric acid plus glycine as fuel. The minimum crystallite size of ceria powder is obtained by combustion synthesis of ceric ammonium nitrate and citric acid. The ceria powder produced by combustion synthesis of ceric ammonium nitrate and citric acid and glycine has less agglomeration of particles than other techniques.
How to Reap the Induced Technological Bonus? A Mechanism and Illustrative Implementation  [PDF]
Gouranga G. Das
Modern Economy (ME) , 2010, DOI: 10.4236/me.2010.12008
Abstract: Exogenous technical progress can have uneven impacts on productivity contingent on absorptive capacity, structural congruence and trade intensity. The paper illustrates the role of enabling behind-the-border factors for effective absorption and is pertinent for discussing issues like ‘Europe 2020’or Lisbon strategy for inclusive growth. Drawing on our model, we illustrate that the capture-parameter is the propellant force for effective assimilation of foreign technology of recent vintage. The capture parameter is the outcome of endogenous decision-making process. The ‘productivity bonus’ mechanism leaves room for changing the results via skill-mix composition. However, it awaits implementation in a large-scale economy-wide modeling framework for further extension.
The factorial structure of self-reported androgen-promoted physiological traits  [PDF]
Lee Ellis, Shyamal Das
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.210144
Abstract: Androgens make major contributions to average sex differences in anatomy, physiology, and behavior. Despite having established their crucial role in sexual differentiation, much remains to be learned about how androgens coordinate their influences. The present study was undertaken to shed light on androgenic effects on the body using self-reported survey data. We analyzed the ratings provided by over 11,000 college students on the magnitude of eleven traits that previous research has shown to be influenced by testosterone or other androgens. Predictably, the average values for all eleven traits were significantly greater in males than in females. Nevertheless, when data were analyzed separately according to sex of the respondents, some of the traits failed to positively correlate with one another, suggesting that not all an-drogen-influenced traits differentiate in a simple fashion. Factor analysis of these eleven traits by sex reinforced this view by identifying four factors. In men, the primary factor loaded most heavily on: masculine body build, masculine mannerisms, overall physical strength, upper body strength, and lower body strength. The primary factor for women was limited to: upper body strength, lower body strength, and overall physical strength. In both sexes, the primary factor was interpreted as reflecting the influence of perinatal and post-pubertal testosterone exposure. The other three factors may reflect the effects of other androgens (e.g., androstenediol), or the influence of female hormones such as estradiol. Findings were discussed in terms of future use of self-reported physiological measures for assessing androgenic effects on the human body.
Effect of calcium and diltiazem on phenylhydrazine-induced oxidative injury in goat erythrocytes  [PDF]
Kaushik Das, Jharna Bhattacharyya
Health (Health) , 2010, DOI: 10.4236/health.2010.210181
Abstract: Lipid peroxidation, hemolysis and thiol contents were studied in intact goat erythrocytes exposed to phenylhydrazine. An increase in lipid peroxidation, hemolysis and thiol content was observed after phenylhydrazine treatment of erythrocyte. Extracellular Ca2+ potentiates the phenylhydrazine-induced lipid peroxidation and hemoly- sis of erythrocytes significantly. Ca2+ does not influence much the thiol content of phenylhydrazine treated erythrocytes. No effect of Ca2+ on control lipid peroxidation, hemolysis and thiol contents of erythrocytes was observed. Diltiazem and EDTA inhibited the increased responses of lipid peroxidation and hemolysis due to Ca2+. However the thiol content was not much influenced by either diltiazem or EDTA. The results suggest that oxidative damage of erythrocyte caused by phenyl hydrazine could be prevented by calcium channel antagonist, diltiazem, which may act as antioxidant also.
Adaptive Processing Gain Data Services in Cellular CDMA in Presence of Soft Handoff with Truncated ARQ  [PDF]
Dipta DAS, Sumit KUNDU
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.22017
Abstract: An adaptive data transmission scheme based on variable spreading gain (VSG) is studied in cellular CDMA network in presence of soft handoff (HO). The processing gain is varied according to traffic intensity meet-ing a requirement on data bit error rate (BER). The overall performance improvement due to processing gain adaptation and soft HO is evaluated and compared with a fixed rate system. The influence of soft HO pa-rameters on rate adaptation and throughput and delay performance of data is indicated. Further truncated automatic repeat request (T-ARQ) is used in link layer to improve the performance of delay sensitive ser-vices. The joint impact of VSG based transmission in presence of soft handoff at physical layer and T-ARQ at link layer is evaluated. A variable packet size scheme is also studied to meet a constraint on packet loss.
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