Numerical studies of the scattering of light from a two-dimensional randomly rough interface between two dielectric media

The scattering of polarized light incident from one dielectric medium on its two-dimensional randomly rough interface with a second dielectric medium is studied. A reduced Rayleigh equation for the scattering amplitudes is derived for the case where p- or s-polarized light is incident on this interface, with no assumptions being made regarding the dielectric functions of the media. Rigorous, purely numerical, nonperturbative solutions of this equation are obtained. They are used to calculate the reflectivity and reflectance of the interface, the mean differential reflection coefficient, and the full angular distribution of the intensity of the scattered light. These results are obtained for both the case where the medium of incidence is the optically less dense medium, and in the case where it is the optically more dense medium. Optical analogues of the Yoneda peaks observed in the scattering of x-rays from metal surfaces are present in the results obtained in the latter case. Brewster scattering angles for diffuse scattering are investigated, reminiscent of the Brewster angle for flat-interface reflection, but strongly dependent on the angle of incidence. When the contribution from the transmitted field is added to that from the scattered field it is found that the results of these calculations satisfy unitarity with an error smaller than $10^{-4}$.Comment: 25 pages, 14 figure

Stringent Nucleotide Recognition by the Ribosome at the Middle Codon Position.

Accurate translation of the genetic code depends on mRNA:tRNA codon:anticodon base pairing. Here we exploit an emissive, isosteric adenosine surrogate that allows direct measurement of the kinetics of codon:anticodon University of California base formation during protein synthesis. Our results suggest that codon:anticodon base pairing is subject to tighter constraints at the middle position than at the 5'- and 3'-positions, and further suggest a sequential mechanism of formation of the three base pairs in the codon:anticodon helix

DSS Model for Profit Maximization at Customer Enquiry Evaluation Stage

This paper presents an optimal method and a heuristic approach which aims at maximizing the profit when responding to a set of customer enquiries under limited capacity. The model takes into consideration the quantity of available-to-promise (ATP) which measures the capability to fill customer orders, along with enquiry quantity and product price. The optimal method and the heuristic approach are tested using ATP, product price and enquiry quantity each at their different levels. From the example conducted, it is found that (1) the optimal model can help to make appropriate decision for selecting a subset of enquiries, and (2) the heuristic approach can produce a result within 5% from the optimum achieved by optimal method for most parameter settings.Singapore-MIT Alliance (SMA

The DNA-binding domain of human papillomavirus type 18 E1. Crystal structure, dimerization, and DNA binding

High risk types of human papillomavirus, such as type 18 (HPV-18), cause cervical carcinoma, one of the most frequent causes of cancer death in women worldwide. DNA replication is one of the central processes in viral maintenance, and the machinery involved is an excellent target for the design of antiviral therapy. The papillomaviral DNA replication initiation protein E1 has origin recognition and ATP-dependent DNA melting and helicase activities, and it consists of a DNA-binding domain and an ATPase/helicase domain. While monomeric in solution, E1 binds DNA as a dimer. Dimerization occurs via an interaction of hydrophobic residues on a single alpha-helix of each monomer. Here we present the crystal structure of the monomeric HPV-18 E1 DNA-binding domain refined to 1.8-A resolution. The structure reveals that the dimerization helix is significantly different from that of bovine papillomavirus type 1 (BPV-1). However, we demonstrate that the analogous residues required for E1 dimerization in BPV-1 and the low risk HPV-11 are also required for HPV-18 E1. We also present evidence that the HPV-18 E1 DNA-binding domain does not share the same nucleotide and amino acid requirements for specific DNA recognition as BPV-1 and HPV-11 E1

Framework to Manage Customer Enquiries for SMEs

For most Smaller Manufacturing Enterprises (SMEs), how to manage customer enquiries at the customer enquiry stage is of great importance to maintain the competitive advantage and secure future customer orders. A lack of co-ordination between marketing/sales and production at this stage often leads to confirmed orders being delivered later than promised and/or being produced at a loss. In the paper, the problems and the solutions for managing customer enquiries faced by many SMEs are addressed. A general process for dealing with customer enquiries at the customer enquiry stage and a corresponding DSS approach are presented in detailed. The SMEs would benefit from the proposed DSS in which the considerations of current material and production capacity are given to the customer enquiry management process.Singapore-MIT Alliance (SMA

Antibiotic Use in Some Nigerian Communities: Knowledge and Attitudes of Consumers

Purpose: To assess the knowledge and attitude of consumers in Jos, Nigeria towards the use of antibiotics. Methods: A cross-sectional questionnaire survey involving 430 clients of registered community pharmacy outlets located in some communities in Jos, Nigeria was conducted in November, 2011. Data collected were analysed using SPSS version 16 and logistic regression was used to determine independent predictors of low antibiotic knowledge. Results: About 56.5 % of respondents reported using an antibiotic within a month preceding the survey, with a prevalence of 22.3 % of self-medication use of antibiotics among respondents. The antibiotic knowledge assessment test revealed that 30.5% of respondents had low knowledge; while 40.9% and 28.6 % of respondents had intermediate and high knowledge levels respectively. Respondents’ educational level was the only demographic predictor (p < 0.01) of low antibiotic knowledge found, as those with primary level of education were more likely (OR = 13.224; CI = 3.296-53.052) to have low antibiotic knowledge than those with tertiary education. Respondents showed negative attitude (< 50 % positive response rate) in about 60 % of the attitude statements they responded to. The most common negative attitudes demonstrated by respondents were their expectation to be prescribed an antibiotic for cold (66.3 %) and taking an antibiotic when they have cold to get better quickly (60.9 %). However, respondents demonstrated positive attitudes in looking at the expiry dates of antibiotics before using them (93.3 %), and taking antibiotics according to the instructions on the label (84.2 %). Conclusion: The study showed that inadequate antibiotic knowledge and negative attitudes towards antibiotics use exists among consumers

Calculation of the Coherent Synchrotron Radiation Impedance from a Wiggler

Most studies of Coherent Synchrotron Radiation (CSR) have only considered the radiation from independent dipole magnets. However, in the damping rings of future linear colliders, a large fraction of the radiation power will be emitted in damping wigglers. In this paper, the longitudinal wakefield and impedance due to CSR in a wiggler are derived in the limit of a large wiggler parameter $K$. After an appropriate scaling, the results can be expressed in terms of universal functions, which are independent of $K$. Analytical asymptotic results are obtained for the wakefield in the limit of large and small distances, and for the impedance in the limit of small and high frequencies.Comment: 10 pages, 8 figure