Impact of rRNA methylations on ribosome recycling and fidelity of initiation in Escherichia coli

Ribosomal RNA (rRNA) contains a number of modified nucleosides in functionally important regions including the intersubunit bridge regions. As the activity of ribosome recycling factor (RRF) in separating the large and the small subunits of the ribosome involves disruption of intersubunit bridges, we investigated the impact of rRNA methylations on ribosome recycling. We show that deficiency of rRNA methylations, especially at positions 1518 and 1519 of 16S rRNA near the interface with the 50S subunit and in the vicinity of the IF3 binding site, adversely affects the efficiency of RRF-mediated ribosome recycling. In addition, we show that a compromise in the RRF activity affords increased initiation with a mutant tRNA(fMet) wherein the three consecutive G-C base pairs ((29)GGG(31):39CCC41), a highly conserved feature of the initiator tRNAs, were mutated to those found in the elongator tRNA(Met) ((29)UCA(31):(39)psi GA(41)). This observation has allowed us to uncover a new role of RRF as a factor that contributes to fidelity of initiator tRNA selection on the ribosome. We discuss these and earlier findings to propose that RRF plays a crucial role during all the steps of protein synthesis.

X-ray absorption spectra of niobium dichalcogenides and their first-row transition-metal intercalates

X-ra!. K-absorption spectra of niobium in niobium dichalcogenides. namely NbS, and NbSe, and their first-row transition-metal intercalates Mi P 3N bSz (M = Cr. Mn. Fe. Co. Ni) and Ml#,NbSe2 (M = Fe. CO). have been measured together with those in niobium metal. The spectra of these materials are \er? similar to one another. They reflect the transitions to the partially filled niobium d band with some p character. A bariety of x-ray absorption nearedge structures (XASES) associated with the K edges of intercalated atoms are also presented and discussed.

A nuclear magnetic resonance study of tetramethylammonium tribromocadmate

Proton spin lattice relaxation (T1) in (CH3)4NCdBr3 at different Larmor frequencies (10, 20 and 30 MHz) has been studied in the temperature range 77 to 400 K. The variations in T1 at high temperature are independent of frequency and show a maximum due to spin rotation- interaction. The other features are interpreted as being due to isotropic tumbling of the tetramethylammonium ion and random reorientation of the CH3 group. The CW spectrum remained narrow up to 77 K and develops a wing structure at low temperatures. This observation is attributed to a possible tunnelling motion of the CH3 group, which has rather low activation energy as demonstrated by the study of T1.

Risk Minimizing Option Pricing in a Semi-Markov Modulated Market

We address risk minimizing option pricing in a semi-Markov modulated market where the floating interest rate depends on a finite state semi-Markov process. The growth rate and the volatility of the stock also depend on the semi-Markov process. Using the Föllmer–Schweizer decomposition we find the locally risk minimizing price for European options and the corresponding hedging strategy. We develop suitable numerical methods for computing option prices.

On the orientation of grain boundaries in cadmium recrystallized during hot deformatio

The authors are grateful to Professor K. P. Abraham for the provision of facilities and encouragement. One of us (PRR) acknowledges the award of a National Associateship by the UGC which facilitated a short-time visit to the Indian Institute of Science.

Influence of Band Non-Parabolicity on Few Ballistic Properties of III-V Quantum Wire Field Effect Transistors Under Strong Inversion

A simplified yet analytical approach on few ballistic properties of III-V quantum wire transistor has been presented by considering the band non-parabolicity of the electrons in accordance with Kane's energy band model using the Bohr-Sommerfeld's technique. The confinement of the electrons in the vertical and lateral directions are modeled by an infinite triangular and square well potentials respectively, giving rise to a two dimensional electron confinement. It has been shown that the quantum gate capacitance, the drain currents and the channel conductance in such systems are oscillatory functions of the applied gate and drain voltages at the strong inversion regime. The formation of subbands due to the electrical and structural quantization leads to the discreetness in the characteristics of such 1D ballistic transistors. A comparison has also been sought out between the self-consistent solution of the Poisson's-Schrodinger's equations using numerical techniques and analytical results using Bohr-Sommerfeld's method. The results as derived in this paper for all the energy band models gets simplified to the well known results under certain limiting conditions which forms the mathematical compatibility of our generalized theoretical formalism.

Orientation Of Grain-Boundaries In Cadmium Recrystallized During Hot Deformation

The authors are grateful to Professor K. P. Abraham for the provision of facilities and encouragement. One of us (PRR) acknowledges the award of a National Associateship by the UGC which facilitated a short-time visit to the Indian Institute of Science.

Coalition Formation With Communication Ranges and Moving Targets

A team of unmanned aerial vehicles (UAVs) with limited communication ranges and limited resources are deployed in a region to search and destroy stationary and moving targets. When a UAV detects a target, depending on the target resource requirement, it is tasked to form a coalition over the dynamic network formed by the UAVs. In this paper, we develop a mechanism to find potential coalition members over the network using principles from internet protocol and introduce an algorithm using Particle Swarm Optimization to generate a coalition that destroys the target is minimum time. Monte-Carlo simulations are carried out to study how coalition are formed and the effects of coalition process delays.

Regioselective synthesis of bicyclo[4.2.1]nonane-2,8-diones via BF3.Et2O mediated intramolecular diazo ketone insertion reaction

Treatment of the diazo diones 11a-d with boron trifluoride diethyl etherate furnished the bicyclo[4.2.1]nonane-2,g-diones 15a-d in a highly regioselective manner. (C) 1999 Elsevier Science Ltd. All rights reserved.

Accelerating Information Diffusion in Social Networks Under the Susceptible-Infected-Susceptible Epidemic Model

Standard Susceptible-Infected-Susceptible (SIS) epidemic models assume that a message spreads from the infected to the susceptible nodes due to only susceptible-infected epidemic contact. We modify the standard SIS epidemic model to include direct recruitment of susceptible individuals to the infected class at a constant rate (independent of epidemic contacts), to accelerate information spreading in a social network. Such recruitment can be carried out by placing advertisements in the media. We provide a closed form analytical solution for system evolution in the proposed model and use it to study campaigning in two different scenarios. In the first, the net cost function is a linear combination of the reward due to extent of information diffusion and the cost due to application of control. In the second, the campaign budget is fixed. Results reveal the effectiveness of the proposed system in accelerating and improving the extent of information diffusion. Our work is useful for devising effective strategies for product marketing and political/social-awareness/crowd-funding campaigns that target individuals in a social network.