40,349 research outputs found

    Reply on `comment on our paper `Single two-level ion in an anharmonic-oscillator trap: Time evolution of the Q function and population inversion ''

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    We show here that the model Hamiltonian used in our paper for ion vibrating in a q-analog harmonic oscillator trap and interacting with a classical single-mode light field is indeed obtained by replacing the usual bosonic creation and annihilation operators of the harmonic trap model by their q-deformed counterparts. The approximations made in our paper amount to using for the ion-laser interaction in a q-analog harmonic oscillator trap, the operator F_{q}=exp{-(|\epsilon|^2}/2)}exp{i\epsilon A^{\dagger}}exp{i\epsilon A}, which is analogous to the corresponding operator for ion in a harmonic oscillator trap that is F=exp(ϵ2/2)expiϵaexpiϵaF=exp{-(|\epsilon|^2 /2)}exp{i\epsilon a^{\dagger }}exp{i\epsilon a}. In our article we do not claim to have diagonalized the operator, Fq=expiϵ(A+A)F_q = exp{i \epsilon (A^{\dagger}+A)}, for which the basis states |g,m> and |e,m> are not analytic vectors.Comment: Revtex, 4pages. To be Published in Physical Review A59, NO.4(April 99

    Differences in intention to use educational RSS feeds between Lebanese and British students: A multi‑group analysis based on the technology acceptance model

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    Really Simple Syndication (RSS) offers a means for university students to receive timely updates from virtual learning environments. However, despite its utility, only 21% of home students surveyed at a university in Lebanon claim to have ever used the technology. To investigate whether national culture could be an influence on intention to use RSS, the survey was extended to British students in the UK. Using the Technology Adoption Model (TAM) as a research framework, 437 students responded to a questionnaire containing four constructs: behavioral intention to use; attitude towards benefit; perceived usefulness; and perceived ease of use. Principle components analysis and structural equation modelling were used to explore the psychometric qualities and utility of TAM in both contexts. The results show that adoption was significantly higher, but also modest, in the British context at 36%. Configural and metric invariance were fully supported, while scalar and factorial invariance were partially supported. Further analysis shows significant differences between perceived usefulness and perceived ease of use across the two contexts studied. Therefore, it is recommended that faculty demonstrate to students how educational RSS feeds can be used effectively to increase awareness and emphasize usefulness in both contexts

    Schr\"{o}dinger cat state of trapped ions in harmonic and anharmonic oscillator traps

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    We examine the time evolution of a two level ion interacting with a light field in harmonic oscillator trap and in a trap with anharmonicities. The anharmonicities of the trap are quantified in terms of the deformation parameter τ\tau characterizing the q-analog of the harmonic oscillator trap. Initially the ion is prepared in a Schr\"{o}dinger cat state. The entanglement of the center of mass motional states and the internal degrees of freedom of the ion results in characteristic collapse and revival pattern. We calculate numerically the population inversion I(t), quasi-probabilities Q(t),Q(t), and partial mutual quantum entropy S(P), for the system as a function of time. Interestingly, small deformations of the trap enhance the contrast between population inversion collapse and revival peaks as compared to the zero deformation case. For \beta =3 and 4,(4,(% \beta determines the average number of trap quanta linked to center of mass motion) the best collapse and revival sequence is obtained for \tau =0.0047 and \tau =0.004 respectively. For large values of \tau decoherence sets in accompanied by loss of amplitude of population inversion and for \tau \sim 0.1 the collapse and revival phenomenon disappear. Each collapse or revival of population inversion is characterized by a peak in S(P) versus t plot. During the transition from collapse to revival and vice-versa we have minimum mutual entropy value that is S(P)=0. Successive revival peaks show a lowering of the local maximum point indicating a dissipative irreversible change in the ionic state. Improved definition of collapse and revival pattern as the anharminicity of the trapping potential increases is also reflected in the Quasi- probability versus t plots.Comment: Revised version, 16 pages,6 figures. Revte

    Effect of nitrogen and sulphur nutrition on storage protein quality in soybean [Glycine max (L.) Merrill]

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    The relative availabilities of nitrogen and sulphur can modulate seed storage protein composition in grain legumes and cereals. Soybean contains two major seed storage proteins, glycinins and ?-conglycinins that account for approximately 70% of total protein and their composition is affected by nitrogen and sulphur supplies. The present study demonstrated the effect of sulphur (Gypsum @ 20 kg S ha-1 ) and recommended a dose of nitrogen (Urea @ 31.25 kg N ha-1 ) alone or in combination on accumulation patterns of various protein fractions and protein quality in soybean seeds under agro-climatic conditions of Punjab. Application of nitrogen or sulphur alone decreased the relative proportion of ?-subunit of purified ?-conglycinin fraction than control. The acidic polypeptides of glycinin fraction of globulin and 11S/7S ratio were increased in all the treatments in comparison to control, and the maximum increase was reported in the combined application of gypsum with the recommended dose of urea. The lower proportion of total 7S, increased acidic polypeptides and improved 11S:7S ratio by combined treatment of nitrogen and sulphur suggests that gypsum @ 20 kg S ha-1 can be beneficial when applied along the recommended nitrogen dose to improve soybean protein quality