Browsing by Author "S.P. Tiwari"

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A topology for fuzzy automata
(Springer Verlag, 2002) Arun K. Srivastava; S.P. Tiwari
This work is an introductory investigation, on the lines of [9] and [10], into some topological aspects of fuzzy machines (studied in [4-8]), wherein we introduce a topology on the state-set of a fuzzy automaton and use it, together with some standard topological results, to deduce some fuzzy automata theoretic results given in [4-8]. © Springer-Verlag Berlin Heidelberg 2002.
Athermal physiological effects of microwaves on a cynobacterium Nostoc muscorum: evidence for EM-memory bits in water
(Kluwer Academic Publishers, 1994) S.P. Singh; Subas Rai; A.K. Rai; S.P. Tiwari; S.S. Singh; Samarketu; J. Abraham
Athermal physiological effects of continuous wave and modulated microwaves were studied on a cynobacterium Nostoc muscorum. The study shows that different microwave frequencies in continuous wave and modulated modes produced significantly different physiological effects on the algae. Water-mediated bioeffects further present additional proof that water has the capability to remember the imposed electromagnetic field characteristics for an extended period of time. © 1994 IFMBE.
Characterizations of rough finite state automata
(Springer Verlag, 2017) Shambhu Sharan; Arun K. Srivastava; S.P. Tiwari
The purpose of this paper is to discuss the properties such as separatedness, connectedness and retrievability of a rough finite state automaton. The results for the relationship among the above properties are discussed and the concept of product of two rough finite state automata is introduced. © 2015, Springer-Verlag Berlin Heidelberg.
Effect of modulated microwave frequencies on the physiology of a cyanobacterium, Anabaena doliolum
(1999) Subash Rai; S.P. Singh; Samarketu; S.P. Tiwari; A.K. Mishra; K.D. Pandey; A.K. Rai
The effect of microwave modulated with square waves of different pulse repetition frequencies was studied on the physiologic behavior of the cyanobacterium Anabaena doliolum. The organism was exposed either directly after inoculating the nutrient solution or indirectly by exposing the nutrient solution before inoculation with the cyanobacterium cells for 1 h to microwave (9.575 GHz) modulated with square wave pulse repetition frequencies of 1000, 700, 500, 200, 100, and 50 Hz at a fixed incident power density (0.658 mW/cm2). This study reveals that microwaves athermally induce different biologic effects, perhaps by changing the structures of water. Modulation frequency-dependent water structures appear to cause the biologic effects by differentially partitioning the ions, altering the rate and/or directions of biochemical reactions, or other mechanisms.
Effect of modulated microwave frequencies on the physiology of a cyanobacterium, Anabaena doliolum
(Marcel Dekker Inc., 1999) Subash Rai; S.P. Singh; Samarketu; S.P. Tiwari; A.K. Mishra; K.D. Pandey; A.K. Rai
The effect of microwave modulated with square waves of different pulse repetition frequencies was studied on the physiologic behavior of the cyanobacterium Anabaena doliolum. The organism was exposed either directly after inoculating the nutrient solution or indirectly by exposing the nutrient solution before inoculation with the cyanobacterium cells for 1 h to microwave (9.575 GHz) modulated with square wave pulse repetition frequencies of 1000, 700, 500, 200, 100, and 50 Hz at a fixed incident power density (0.658 mW/cm2). This study reveals that microwaves athermally induce different biologic effects, perhaps by changing the structures of water. Modulation frequency-dependent water structures appear to cause the biologic effects by differentially partitioning the ions, altering the rate and/or directions of biochemical reactions, or other mechanisms.
Effect of NaCl on nitrogen fixation of unadapted and NaCl-adapted Azolla pinnata-Anabaena azollae
(2001) Vandna Rai; S.P. Tiwari; Ashwani K. Rai
Exposure of Azolla pinnata-Anabaena azollae to NaCl induced a sharp decline in nitrogenase activity. A lethal dose of NaCl (40 mM) for the growth of A. pinnata-A. azollae complex could inhibit the nitrogenase activity by 39%, revealing for higher sensitivity of general growth to NaCl than the nitrogenase activity. Salinity caused a distinct shift in the profile of heterocyst differentiation in cavities of individual leaves with an increase in heterocyst frequency towards the apex, as well as increased the heterocyst frequency. An observed 16% heterocyst frequency in unadapted complex under non-saline condition rose to 18.7% after exposing it to 60 mM NaCl in comparison to 17.4% in adapted complex at identical NaCl concentration. The heterocyst frequency and its pattern in different leaf lobes of unadapted complex exposed to 60 mM NaCl was significantly different, whilst the difference was non-significant between unadapted complex under non-saline condition and the adapted complex at 60 mM NaCl. The increase in heterocyst frequency did not match with the nitrogenase activity. Dinitrogen fixation ability was maximum in mature median leaf cavities and minimum in apex, while NaCl-induced reduction in the nitrogenase activity was most marked in the cyanobionts occupying mature median leaf cavities. © 2001 Elsevier Science B.V. All rights reserved.
Fuzzy Chu spaces and fuzzy topologies
(World Scientific Publishing Co. Pte Ltd, 2004) Arun K. Srivastava; S.P. Tiwari
We show that each fuzzy (or in general L-) topological space can be represented as a fuzzy (or an L-) Chu space. Further, this representation preserves products, coproducts, tensor products, and hom-sets (together with the structures they are enriched with).
Fuzzy rough sets, fuzzy preorders and fuzzy topologies
(2013) S.P. Tiwari; Arun K. Srivastava
This paper shows that observations made by different authors at different times regarding one-to-one correspondence between the family of fuzzy preorders on a nonempty set and the family of all fuzzy topologies on this set satisfying certain extra conditions are essentially equivalent. © 2012 Elsevier B.V. All rights reserved.
IF-topologies and IF-automata
(2010) Arun K. Srivastava; S.P. Tiwari
The purpose of this work is to indicate that a study of IF-automata (also called, intuitionistic fuzzy automata) can be carried out much on the same lines as the one done for fuzzy automata in Srivastava and Tiwari (Proceedings of 2002 AFSS international conference on fuzzy systems. Lecture notes in artificial intelligence, vol 2275. Springer, Berlin, pp 485-490, 2002). It is also shown that two IF-topologies (also called, intuitionistic fuzzy topologies) can be associated with the state-sets of IF-fuzzy automata whose level topologies have interesting relationships with the topologies introduced by Srivastava and Tiwari (above mentioned) for fuzzy automata. © 2009 Springer-Verlag.
Intuitionistic fuzzy automata and associated fuzzy topologies
(2007) Arun K. Srivastava; S.P. Tiwari
It is shown that two intuitionistic fuzzy topologies can be associated with an intuitionistic fuzzy automata which have interesting relationships with the topologies introduced in [9] for fuzzy automata. © 2007 IEEE.
Isolation and characterization of transposon-induced chlorate resistant mutants of the cyanobacterium Anabaena species PCC 7120
(2000) A.K. Rai; S.P. Tiwari
Mutants of Anabaena sp. PCC 7120 resistant to chlorate were isolated using transposon mutagenesis. The Anabaena population of 5 x 107 cells ml-1 and log phase Escherichia coli cultures in undisturbed conditions produced maximum exconjugants. Nitrate-promoted growth and cellular constituents observed in the parent were absent in the mutants. Nitrate repressed heterocyst formation and N2-fixation in the parent, but had little or no effect on the mutants.
Magnetobiological effects on a cyanobacterium, anabaena doliolum
(Informa Healthcare, 1994) S.S. Singh; S.P. Tiwari; J. Abraham; S. Rai; Ashwani K. Rai
Exposure time and magnetic-pole-dependent physiological response of a cyanobacterium, Anabaena doliolumwere studied by exposing the samples to two poles [north (N) and south (S)] of a 0.3 Tesla permanent magnet for 1-6 h. Study revealed that both magnetic poles, N and S, produce different effects, depending on the length of exposure. However, physiological response of the cyanobacterium to N + S mixtures was significantly different from the response to either of the poles, N or S, suggesting a change in structural chemistry of the water or nutrient solution responsible for the magnetobiological effects. © 1994 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
Magnetobiological effects on a cyanobacterium, Anabaena doliolum
(1994) S.S. Singh; S.P. Tiwari; J. Abraham; S. Rai; A.K. Rai
[No abstract available]
Microbial evaluation of water bodies fRom Jaunpur, UP, India
(2010) R.K. Singh; Avanish Pandey; Rahul Pandey; S.P. Tiwari
Physicochemical properties and microbial evaluation of local water bodies of district Jaunpur were studied. Various parameters analyzed showed deviations from the normal permissible limits indicating pollution load. Microbial analysis suggested the presence of coliform bacteria in all the water bodies indicating fecal contamination. Toxic cyanobacterial strains were also observed in these water bodies. Copyright © EM International.
Mutants of the cyanobacterium Anabaena sp. PCC 7120 altered in nitrate transport and reduction
(1999) Ashwani K. Rai; S.P. Tiwari
Nitrate assimilation-defective mutants SP7, SP9, and SP17 of the cyanobacterium Anabaena sp. PCC 7120 were isolated by use of transposon mutagenesis and screened on medium containing chlorate, SP7 and SP17 represented nitrate reductase-defective nature, while mutant SP9 appeared to be a regulatory mutant exhibiting pleiotropic behavior. Kinetics of nitrate uptake system exhibited K(s) values of 31-38 μM for parent, SP7, and SP17 strains; however, mutant SP9 exhibited a high K(s) value of 109.5 μM. Defective nitrate reductase was apparent in mutant SP7 and SP9, while mutant SP17 exhibited partial defective nature. Methyl viologen-dependent NR activity in parent strain presented a biphasic nature with K(m) values of 0.13 and 2.47 mM, whereas a single K(m) value (2.96 mM) was observed for mutant sP17. Mutant SP9 was also defective in nitrite uptake and reduction. Mutant strains exhibited derepressed nitrogenase activity in the presence of nitrate, while glutamine synthetase activity remained unaltered.
NO3- nutrition and salt tolerance in the cyanobacterium Anabaena sp. PCC 7120 and mutant strains
(Blackwell Publishing Ltd., 1999) A.K. Rai; S.P. Tiwari
PCC 7120 and its nitrate assimilation-defective mutants was inversely proportional to the NaCl concentration in the medium. Presence of nitrate in the saline medium protected the growth of the parent but not of the mutant strains from salt toxicity. On the other hand, ammonium nitrogen protected the growth of all the strains from salt toxicity. However, the effect was less than that of nitrate. An altered sodium transport system was evident in the mutant strains and was most marked in mutant SP9. The cellular sodium concentration in parent and mutant strains also varied. Although mutant SP9 exhibited the lowest level of cellular sodium, it was as sensitive to salt toxicity as other strains. It is assumed that merely the presence of a toxic level of NaCl in the ambient environment is sufficient to damage the structural and functional components of the plasma membrane.
On a decomposition of fuzzy automata
(2005) S.P. Tiwari; Arun K. Srivastava
The purpose of the present work is to obtain a unique decomposition of a fuzzy automaton (possibly with infinite state-set) as a union of a regular closed decomposable subautomaton and a source-splitting subautomaton. © 2004 Elsevier B.V. All rights reserved.
On another decomposition of Fuzzy Automata
(2011) Arun K. Srivastava; S.P. Tiwari
After introducing the notion of an f-primary of a fuzzy automaton, this paper presents a decomposition of a fuzzy automaton (possibly with infinite state-set) as a union of its f-primaries. En route, it is also shown that the concepts of primaries and f-primaries of a fuzzy automaton coincide in the case of compact fuzzy automaton. © 2011 World Academic Press, UK. All rights reserved.
On categories of fuzzy Petri nets
(2011) S.P. Tiwari; Arun K. Srivastava
We introduce the concepts of fuzzy Petri nets and marked fuzzy Petri nets along with their appropriate morphisms, which leads to two categories of such Petri nets. Some aspects of the internal structures of these categories are then explored, for example, their reflectiveness/coreflectiveness and symmetrical monoidal closed structure. © 2011 Arun K. Srivastava and S. P. Tiwari.
On relationships among fuzzy approximation operators, fuzzy topology, and fuzzy automata
(2003) Arun K. Srivastava; S.P. Tiwari
The fuzzy approximation operator associated with an approximation space (X,R) turns out to be a (saturated) Kuratowski fuzzy closure operator on X precisely when the relation R on X is reflexive and transitive. It is shown that all the level topologies of the fuzzy topology so obtained on X coincide. These observations are then applied to fuzzy automata. © 2002 Elsevier B.V. All rights reserved.