Biomedical subjects
Publications and source records attributed to G S Agarwal.
The rotational frequency shift is studied for fields of arbitrary states of coherence and polarization. It is shown that the power spectrum of the field in the rotating frame is influenced both by the degree of polarization and the degree of coherence. Examples for some model field classes are given.
We report interferences in the quantum fluctuations of the output of a parametric amplifier when the cavity is driven by a quantized field at the signal frequency. The interferences depend on the phase fluctuations of the input quantized field and result in splitting of the spectrum of the output, and thus the recent observation [H. Ma, Phys. Rev. Lett. 95, 233601 (2005)10.1103/PhysRevLett.95.233601] of interferences in the classical domain have a very interesting counterpart in the quantum domain. The interferences can be manipulated, for example, by changing the amount of squeezing in the input field.
We present a large family of exact solitary wave solutions of the one-dimensional Gross-Pitaevskii equation, with time-varying scattering length and gain or loss, in both expulsive and regular parabolic confinement regimes. The consistency condition governing the soliton profiles is shown to map onto a linear Schrödinger eigenvalue problem, thereby enabling one to find analytically the effect of a wide variety of temporal variations in the control parameters, which are experimentally realizable. Corresponding to each solvable quantum mechanical system, one can identify a soliton configuration. These include soliton trains in close analogy to experimental observations of Streckeret al. [Nature (London) 417, 150 (2002)], spatiotemporal dynamics, solitons undergoing rapid amplification, collapse and revival of condensates, and analytical expression of two-soliton bound states, to name a few.
The effectiveness of low cost agro-based materials namely, Tamarindus indica seed (TS), crushed coconut shell (CS), almond shell (AS), ground nut shell (GS) and walnut shell (WS) were evaluated for Cr(VI) removal. Batch test indicated that hexavalent chromium sorption capacity (q(e)) followed the sequence q(e)(TS) > q(e)(WS) > q(e)(AS) > q(e)(GS) > q(e)(CS). Due to high sorptive capacity, tamarind seed was selected for detailed sorption studies. Sorption kinetic data followed first order reversible kinetic fit model for all the sorbents. The equilibrium conditions were achieved within 150 min under the mixing conditions employed. Sorption equilibria exhibited better fit to Freundlich isotherms (R>0.92) than Langmuir isotherm (R approximately = 0.87). Hexavalent chromium sorption by TS decreased with increase in pH, and slightly reduced with increase in ionic strength. Cr(VI) removal by TS seems to be mainly by chemisorption. Desorption of Cr(VI) from Cr(VI) laden TS was quite less by distilled water and HCl. Whereas with NaOH, maximum desorption achieved was about 15.3%. When TS was used in downflow column mode, Cr(VI) removal was quite good but head loss increased as the run progressed and was stopped after 200 h.
We report the first measurements, to our knowledge, of the modification of spontaneous emission rates of Eu3+ ions in the visible region owing to an absorbing medium. Precise levels of the absorption coefficient are introduced by codoping with different amounts of Nd3+. We use a binary glass system PbO-B2O3 as the host, the compositional variation of which leads to a change in the real part of the refractive index. Measured lifetimes are found to follow the real cavity model, and the data are analyzed by the model proposed by Scheel et al. [Phys. Rev. A 60, 4094 (1999)]. We give estimates of the parameter that is related to the radius of the cavity around Eu3+.
The recently developed theory that unifies the treatments of polarization and coherence of random electromagnetic beams is applied to study field correlations in Young's interference experiment. It is found that at certain pairs of points the transmitted field is spatially fully coherent, irrespective of the state of coherence and polarization of the field that is incident on the two pinholes.
We develop models for the propagation of intense pulses in solid state media which can have either saturated absorption or reverse absorption. We model subluminal propagation in ruby and superluminal propagation in alexandrite as three and four level systems, respectively, coupled to Maxwell's equations. We present results well beyond the traditional pump-probe approach and explain the experiments of Bigelow et al. [Phys. Rev. Lett. 90, 113903 (2003)]Science 301, 200 (2003)]] on solid state materials.
We report experimental results on the variation of the radiative lifetime of Eu3+ ion embedded in a dielectric with the refractive index n. We dope 1 mol % of Eu3+ into the binary glass system xPbO-(1-x)B2O3. By varying x we have achieved a fairly large variation of the refractive index from 1.7 to 2.2. This enables us to study the local field effects for the first time for ions doped in a solid glassy material. Our measurements are in agreement with the so-called real cavity model. The present measurements are free from the complications arising from reorganizational effects in solvents.
We suggest a way in which entangled photons produced by a type II downconverter can be used for magneto-optical spectroscopy with district advantages. Both collinear and noncollinear geometries can be used. We present quantum mechanical results for the coincidence detection of different polarizations at the output.
We propose a method of generating multipartite entanglement by considering the interaction of a system of N two-level atoms in a cavity of high quality factor with a strong classical driving field. It is shown that, with a judicious choice of the cavity detuning and the applied coherent field detuning, vacuum Rabi coupling produces a large number of important multipartite entangled states. It is even possible to produce entangled states involving different cavity modes. Tuning of parameters also permits us to switch from Jaynes-Cummings to anti-Jaynes-Cummings-like interaction.
A new dot-ELISA kit for detection of Brucella antibodies in human sera was developed and compared with that of serum agglutination test, Rose Bengal plate test, rapid slide agglutination and Coomb's antiglobulin test. Following testing of 120 human sera from suspected patients of occupational risk, 25 gave positive reaction in Rose Bengal plate test, 25 in rapid slide agglutination test, 26 in serum agglutination test, 27 in Coomb's antiglobulin test and 28 in dot-ELISA kit. Dot-ELISA kit picked up more positive than any other Serological test, indicating its superiority over the other laboratory tests for the diagnosis of brucellosis.
We propose a scheme for slowing down decay into a continuum. We make use of a sequence of ultrashort 2pi pulses applied on an auxiliary transition of the system so that there is a destructive interference between the two transition amplitudes--one before the application of the pulse and the other after the application of the pulse. We give explicit results for a structured continuum. Our scheme can also inhibit unwanted transitions.
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Malleo-proteins from synthetic broth mallein of six strains of Pseudomonas mallei were separated by trichloroacetic acid precipitation, ammonium sulfate precipitation and Ultrogel AcA 34 gel filtration chromatography. When tested comparatively with Dutch PPD mallein as standard on P. mallei-sensitized and normal horses all the strains were found to be malleinogenic, trichloroacetic acid precipitated proteins were comparable to Dutch PPD mallein in potency and innocuity whereas ammonium sulfate-precipitated proteins elicited non-specific reactions. Ultrogel AcA 34 chromatographed high molecular weight proteins (MW range > 350,000) were having equal or higher potency and without adverse reactions and low molecular weight proteins (MW range 120,000-170,000) nearly inactive. Ultrogel AcA 34 column fractionation studies revealed that mallein activity was associated with high molecular weight proteins and represented a purer sensitin than PPD mallein for the purpose of mallein test.
Sheep red blood cells (SRBCs) stabilised with formaldehyde, glutaraldehyde, pyruvic aldehyde and double aldehyde were evaluated, in the indirect haemagglutination (IHA) test, for their suitability for the serodiagnosis of brucellosis in bovines. Serum samples from 23 standard tube agglutination test (STAT)-positive and 12 clinically suspected but STAT-negative cows were titrated by the IHA test. Double aldehyde and glutaraldehyde-stabilised SRBCs were found to be more sensitive in the IHA than the formaldehyde or pyruvic aldehyde-stabilised SRBCs. Double aldehyde and glutaraldehyde treatments enabled the IHA to clearly differentiate between the normal and the diseased cows. Double aldehyde-stabilised cells have an edge over the glutaraldehyde-stabilised SRBCs because the former treatment makes the SRBCs readily available for antigen coating without tannic acid activation.
Carbamylation of haemoglobin by methyl isocyanate (MIC) was detected by high-performance liquid chromatography (HPLC) using a photodiode array detector following cyclisation of the N-terminal valine into methyl isopropyl hydantoin (MIH). MIH was also synthesised by reaction of MIC with valine, the chromatographic conditions standardised and the spectrum derived by a photodiode array detector recorded for confirmation of the identity of MIH. This HPLC method is specific, sensitive and suitable for the detection of exposure of blood samples to methyl isocyanate.
Carbamylation of the N-terminal valine of haemoglobin with methyl isocyanate in rats and rabbits has been demonstrated in vitro and in vivo by gas chromatography. N-Methylcarbamylated haemoglobin, converted by cyclization into 3-methyl-5-isopropylhydantoin, has been quantified by gas chromatography. Standard hydantoin was synthesized, chemically characterized and used for calibration. The method is simple and reliable in the concentration range 0.06-2 nmol. Carbamylation of haemoglobin by methyl isocyanate in vivo in rats can be identified only above a dose of 1.05 mg/l in inhalation exposures. It is inferred that methyl isocyanate in the "active" form crosses the alveolar and erythrocyte membranes and carbamylates the haemoglobin.
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