Fluorescence from relaxed and unrelaxed excited state of benzil

This note reports the detection of fluorescence from unrelaxed S₁ state of benzil using Boxcar gating technique. The new emission exhibits mirror image relationship with absorption and blue shift in hydroxylic solvent. In order to ascertain wheter geometrical relaxation occurs in S₁ state, intensities of fluorescence from relaxed and unrelaxed state have been compared at various temperatures.     

Spectroscopic evidences for grafting of N-vinyl carbazole on cellulose-acetate film

N-vinyl carbazole (VCZ) was grafted on cellulose acetate film using simultaneous cobalt-60-γ ray irradiation grafting technique. Absorption, excitation, and emission spectral studies on the grafted film were carried out to ascertain the grafting of VCZ on the polymer matrix. Laser-flash photolysis studies with the solution of grafted film indicate the opening of the double bond of VCZ, which leads to the grafting. On the basis of the observed results, the mechanism of grafting in the system was proposed. © 1994 John Wiley & Sons, Inc.     

Reactions of cobalt(III) complexes with free radicals derived from thymine

The nature of interaction of Co(III) complexes such as Co(III)EDTA and Co(III)NTA with transient adducts of thymine such as TOH^˙, T^˙?, and TH^˙ formed in the gamma radiolysis of thymine were studied. The study shows that TOH radicals do not undergo electron transfer reaction with Co(III) complexes whence no radiosensitization of thymine by Co(III) complexes was observed. Electron transfer however, takes place from T^˙? and TH^˙ to Co(III) complexes. A plausible mechanism of radiolysis of thymine in presence of Co(III) complexes is discussed. © 1994 John Wiley & Sons, Inc.     

Reductive nitrosylation of tetraoxometallates. Part VIII1. A virtually single step synthesis of azido-nitrosyl derivatives of chromium(I) directly from chromate in aqueous-aerobic media.

Azido-nitrosyl complexes and their derivatives of the types [Cr(NO)(N₃)₅]^3? and [Cr(NO)(N₃)₂(L-L)] [L-L = 2,2′bipyridine (bipy) and 1,10 phenanthroline (phen)] were synthesised directly from chromate ion using hydroxylamine hydrochloride, azide ion and hydroxyl ion and other appropriate ligands virtually in a single step process in an aqueous aerobic medium. The compounds are characterised by IR, molecular weight, molar conductance, magnetic susceptibility, esr and electronic spectral data.     

Estimation of the Sea Level Muon Spectra at Different Zenith Angles below 10 TeV Energy

The moderate energy primary cosmic ray nucleon spectrum has been calculated from the direct measurements of Webber et al., Seo et al., and Menn et al. along with the other results surveyed by Swordy. Using these directly measured primary mass composition results all particle primary nucleon energy spectrum has been constructed using superposition model to estimate the energy spectra of muons from the decay of the cosmic ray non-prompt and prompt mesons in the atmosphere. The Z-factors have been estimated from the CERN LEBC-EHS on the Lorentz invariant cross section results on pp ^±X and pp K^±X inclusive reactions and FNAL data on ^±p ^±X reactions, and duly corrected for A--A collisions. Using these Z-factors the meson energy spectra in the atmosphere have been calculated. The sea level muon energy spectra at zenith angles 0°, 45°, 72°, and 75° have been derived from the decay of non-prompt mesons by adopting standard diffusion equation of hadronic cascades. The contribution of charmed mesons to muon spectrum has also been accounted by adapting the conventional procedure. The derived differential sea level muon energy spectra for energies 10 TeV have been found to follow the power law fits of the form N (E) const. E ^-. Our estimated muon energy spectra at zenith angles 75° have been found comparable with the global spectrograph muon flux results of MARS, DEIS, and MSU groups.     

Implementing EPR Dosimetry for Life-Threatening Incidents: Factors Beyond Technical Performance

Starting with the assumption that a device to detect unplanned radiation exposures is technically superior to current technology, we examine the additional stakeholders and processes that must be considered to move the device from the lab into use. The use is to provide reliable information to triage people for early treatment of exposure to ionizing radiation that could lead to the Acute Radiation Syndrome. The scenario is a major accident or terrorist event that leaves a large number of people potentially exposed, with the resulting need to identify those to treat promptly or not. In vivo EPR dosimetry is the exemplar of such a technique.Three major areas are reviewed: policy considerations, regulatory clearance, and production of the device. Our analysis of policy-making indicates that the current system is very complex, with multiple significant decision-makers who may have conflicting agendas. Adoption of new technologies by policy-makers is further complicated because many sources of expert input already have made public stances or have reasons to prefer current solutions, e.g., some may have conflicts of interest in approving new devices because they are involved with the development or adoption of competing techniques. Regulatory clearance is complicated by not being able to collect evidence via clinical trials of its intended use, but pathways for approval for emergency use are under development by the FDA. The production of the new device could be problematical if the perceived market is too limited, particularly for private manufacturers; for in vivo EPR dosimetry the potential for other uses may be a mitigating factor.Overall we conclude that technical superiority of a technique does not in itself assure its rapid and effective adoption, even where the need is great and the alternatives are not satisfactory for large populations. Many important steps remain to achieve the goals of approval and adoption for use.     

Chance constrained uncertain classification via robust optimization

This paper studies the problem of constructing robust classifiers when the training is plagued with uncertainty. The problem is posed as a Chance-Constrained Program (CCP) which ensures that the uncertain data points are classified correctly with high probability. Unfortunately such a CCP turns out to be intractable. The key novelty is in employing Bernstein bounding schemes to relax the CCP as a convex second order cone program whose solution is guaranteed to satisfy the probabilistic constraint. Prior to this work, only the Chebyshev based relaxations were exploited in learning algorithms. Bernstein bounds employ richer partial information and hence can be far less conservative than Chebyshev bounds. Due to this efficient modeling of uncertainty, the resulting classifiers achieve higher classification margins and hence better generalization. Methodologies for classifying uncertain test data points and error measures for evaluating classifiers robust to uncertain data are discussed. Experimental results on synthetic and real-world datasets show that the proposed classifiers are better equipped to handle data uncertainty and outperform state-of-the-art in many cases.     

Variational formulae for Fuchsian groups over families of algebraic curves

We study the problem of understanding the uniformizing Fuchsian groups for a family of plane algebraic curves by determining explicit first variational formulae for the generators.     

Modelling of Drop Size Distribution of Rain from Rain Rate and Attenuation Measurements at Millimeter and Optical Wavelengths

This paper describes a technique for modelling of rain drop size distributions at Calcutta in terms of negative exponential function, from the measurements of rain rate and attenuation over a dual wavelength LOS link at millimeter and optical frequencies. The DSD model obtained is then used to determine the attenuation at 94 GHz, for comparison with experimentally obtained attenuation at 94 GHz. This is also compared with the attenuation calculated by considering other experimentally obtained DSD models. The best fit negative exponential distribution function (modified M-P model) is presented along with some other experimentally obtained and reference models.     

Nature of the emission band of Dergaon meteorite in the region 5700x2013;6700 Å

An emission band system in the region 5700–6700 Å from Dergaon stoney iron meteorite which fell at Dergaon, India on March 2, 16.40 local time (2001) was excited with the help of a continuous 500 mW Ar⁺ laser. The band system is attributed to silicate (olivine), a major component of the meteorite.