https://www.uni-lj.si/mma/biomedicina%20Macek%20Influenza%20virus%20budding/2013090613550890/

Influenza virus assembly and budding.

Influenza Virus M2 Protein Mediates ESCRT-Independent Membrane Scission

The Interferon-Inducible Protein Viperin Inhibits Influenza Virus Release by Perturbing Lipid Rafts

https://escholarship.org/content/qt7548q7cp/qt7548q7cp.pdf?t=qaem19

Assembly and budding of influenza virus.

We derive a stochastic nonlinear continuum theory to describe the morphological evolution of amorphous surfaces eroded by ion bombardment. Starting from Sigmund's theory of sputter erosion, we calculate the coefficients appearing in the continuum equation in terms of the physical parameters characterizing the sputtering process. We analyze the morphological features predicted by the continuum theory, comparing them with the experimentally reported morphologies. We show that for short time scales, where the effect of nonlinear terms is negligible, the continuum theory predicts ripple formation. We demonstrate that in addition to relaxation by thermal surface diffusion, the sputtering process can also contribute to the smoothing mechanisms shaping the surface morphology. We explicitly calculate an effective surface diffusion constant characterizing this smoothing effect, and show that it is responsible for the low temperature ripple formation observed in various experiments. At long time scales the nonlinear terms dominate the evolution of the surface morphology. The nonlinear terms lead to the stabilization of the ripple wavelength and we show that, depending on the experimental parameters such as angle of incidence and ion energy, different morphologies can be observed: asymptotically, sputter eroded surfaces could undergo kinetic roughening, or can display novel ordered structures with rotated ripples. Finally, we discuss in detail the existing experimental support for the proposed theory, and uncover novel features of the surface morphology and evolution, that could be directly tested experimentally.

Morphology of Ion-Sputtered Surfaces

We studied non-resonant two photon absorption (NRTPA) 5S1/2→5D5/2 of hot Rb atom using a laser emitting at 778nm. The decay channel 5D5/2→6P3/2→5S1/2 is monitored to record the blue fluorescence. T...

Studies on rubidium 5S-5d two-photon absorption

This paper deals with the analysis and experimental study of natural frequencies of vibration of a 4-rod type radio frequency quadrupole (RFQ) linear accelerator. The eigenvalue analysis of the structure has been done both analytically (multispan beam concept) as well as using blocked Lanczos eigenvalue finite element solver with an ability to extract the rigid body modes. This has been done in the mechanical design phase to find the level of agreement between the output of simplified analytical analysis results and the output of a commercial finite element method (FEM) solver, since a full scale RFQ structure is too complex to handle analytically. Experimental validation of the analysis results has been done on the physical 1.7 m RFQ at the installation site. The experimental data obtained were later analyzed and found to be in close agreement with the predicted frequencies in the lower frequency ranges. It gets more and more deviated in the higher frequency ranges. Also some frequencies were observed during experimentation, which were not found in the finite element analysis results. The source of those frequencies are to be further investigated as it may play a predominant role in the design high quality factor beam line cavities for higher operational efficiency.

Modal response of 4-rod type radio frequency quadrupole linac.

In this report, we present an experimental investigation on atomic frequency offset locking (AFOL) of a laser under ladder (Ξ) level coupling scheme. The 5S1/2 → 5P3/2 → 5D5/2 two-photon transition manifold of the rubidium (Rb) atom is chosen to demonstrate the performance of stabilization scheme in terms of frequency stability and tunability. The coherent pump–probe spectroscopy performed on the 5S → 5P → 5D levels results in signatures of two-photon absorption (TPA) and electromagnetically induced transparency (EIT). Here the pump laser is locked to the fringe of a scanning Fabry–Perot interferometer with the help of frequency modulation spectroscopy. The probe laser is subsequently stabilized on the resulting EIT (TPA) signals. It is found that the probe laser attains relative frequency stability as a square root of Allan variance calculated from the frequency noise power density under closed-loop condition. Further, the current locking scheme has wide tuning range {Doppler width of transition manifold. This particular tunable AFOL (TAFOL) scheme can provide large tuning range without compromising the frequency stability and such implementation of TAFOL may open new opportunities in research areas like metrology, ultra precision coherent spectroscopy, etc.

https://iopscience.iop.org/article/10.1088/0031-8949/88/06/065301/pdf

Tunable offset locking in a Ξ system: an experimental study on the rubidium atom

Objectives: We have isolated a total of five newer cholera phages which are novel broad host range to incorporate with the existing phage typing schemes for an extended typing scheme. Materials and Methods: These newly isolated phages were well characterized including the electron micrograph. A total of 300 Vibrio cholerae strains were isolated from the different endemic region in India were included in phage typing study. Results: These phages were found different from the existing phages. Electron microscopic results showed that the phages belonged to myophage and podophage group. Characterization of the phages based on pH, temperature, and organic solvent sensitivity showed differences among the phages used in this study. All the strains of Vibrio O1 were typeable (100%) with the five set of cholera phages. Of these, 40% strains were clustered under Type-1. Conclusion: The newer Vibrio phages are novel and broad host range and will be useful to incorporate with the existing phage typing system for more precisely discriminate the strains of Vibrio cholerae.

Isolation and characterization of novel broad host range bacteriophages of Vibrio cholerae O1 from Bengal

The decay of [sup 98]Rh has been studied using [gamma] and [beta] spectroscopy techniques. The [sup 96]Ru([alpha],[ital pn]) reaction was used to produce [sup 98]Rh and the activities were transported to a low background counting station using a He-jet system. The [beta] end point energy has been determined from the decay of [sup 98[ital g]]Rh to [sup 98]Ru. The end-point energy determined in this study differs considerably from an earlier study using similar technique but agrees well with that of an earlier ([ital p],[ital n]) reaction study. The present study has also resulted in a modified decay scheme (partial) for the decay of [sup 98]Rh.

Alok Chakrabarti

Papers

Studies on rubidium 5S-5d two-photon absorption

Modal response of 4-rod type radio frequency quadrupole linac.

Tunable offset locking in a Ξ system: an experimental study on the rubidium atom

Isolation and characterization of novel broad host range bacteriophages of Vibrio cholerae O1 from Bengal

Decay of 98Rh.