Optical pumping via incoherent Raman transitions

A new optical pumping scheme is presented that uses incoherent Raman transitions to prepare a trapped Cesium atom in a specific Zeeman state within the 6S_{1/2}, F=3 hyperfine manifold. An important advantage of this scheme over existing optical pumping schemes is that the atom can be prepared in any of the F=3 Zeeman states. We demonstrate the scheme in the context of cavity quantum electrodynamics, but the technique is equally applicable to a wide variety of atomic systems with hyperfine ground-state structure.Comment: 8 pages, 4 figure

Frequency Tracking and Parameter Estimation for Robust Quantum State-Estimation

In this paper we consider the problem of tracking the state of a quantum system via a continuous measurement. If the system Hamiltonian is known precisely, this merely requires integrating the appropriate stochastic master equation. However, even a small error in the assumed Hamiltonian can render this approach useless. The natural answer to this problem is to include the parameters of the Hamiltonian as part of the estimation problem, and the full Bayesian solution to this task provides a state-estimate that is robust against uncertainties. However, this approach requires considerable computational overhead. Here we consider a single qubit in which the Hamiltonian contains a single unknown parameter. We show that classical frequency estimation techniques greatly reduce the computational overhead associated with Bayesian estimation and provide accurate estimates for the qubit frequencyComment: 6 figures, 13 page

An interleaved sampling scheme for the characterization of single qubit dynamics

In this paper, we demonstrate that interleaved sampling techniques can be used to characterize the Hamiltonian of a qubit and its environmental decoherence rate. The technique offers a significant advantage in terms of the number of measurements that are required to characterize a qubit. When compared to the standard Nyquist-Shannon sampling rate, the saving in the total measurement time for the interleaved method is approximately proportional to the ratio of the sample rates.Comment: 9 pages, 4 figure

Experimental investigations on fibre reinforced geopolymer concrete as repair material for pavements

Geopolymer is a relatively new construction material which could be produced by the chemical action between alumino-silicate material such as fly ash and alkaline solutions like sodium silicate or sodium hydroxide. Geopolymer concrete (GPC) reduces the CO2 emission by 9 % compared to the concrete made with ordinary portland cement. Fibre reinforced geopolymer concrete (FRGPC) has already been used as a repair material for different construction purposes such as for tunnel linings and sewage pipes repairs due to its improved tensile characteristics and crack control properties. This study involves the experimental investigations on FRGPC as a repair material for rigid pavements. A mixture of sodium silicate and 8M sodium hydroxide solution is used as the alkaline activator to prepare the fly ash based geopolymer concrete. To increase the mechanical properties at ambient temperature calcium additives in the forms of calcium hydroxide and calcium oxide are added separately by replacing fly ash in the proportion 3%, 5% and 7% by weight of fly ash. Further to increase the low tensile strength of GPC, addition of polypropylene fibre in 0.2%, 0.4% and 0.6% by volume of concrete were also incorporated. The aspect ratio of the polypropylene fibres used is 300. The optimum values were determined based on the fresh concrete properties and mechanical properties. The results showed that the 7 day compressive and tensile strengths of FRGPC were increased by 36% and 14% respectively from fly ash GPC. The bond strength between the pavement substrate and the geopolymer repair material is also studied. The bond strength of the fibre reinforced repair material is found to be more than the permissible values as per relevant codes of practice. Abrasion resistance of the repair material is also tested as a measure of durability aspects to check the suitability for usage on rigid pavements. Keywords—Geopolymer Concrete, Alumino-Silicate, Rigid pavements, Substrate, Alkaline solution, Repair materia

Mercaptobenzothiazole or the mercapto-mix: which should be in the standard series?

Mercaptobenzothiazole (MBT) compounds are well known contact allergens. To detect rubber allergic patients we use both MBT (2% in petrolatum) and a mercapto-mix with 4 constituents of 0.5% each in our standard series. In this article the EECDRG presents data of in total 32,475 consecutive tested patients attending the respective contact dermatitis clinics from 11 centres in Europe to determine if the mix and MBT detected the same allergic patients. We found 327 patients positive to the mix or MBT, or to both. 261 were positive to the mix and 254 to MBT. MBT was negative in 73 patients who were positive to the mix. If the mix had not been in the standard series, on average 22% of patients allergic to a mercapto-compound would have been missed, for MBT this would have been on average 20%. All clinics would have missed a significant number of positive reactions if both compounds had not been tested. We conclude, that both the mercapto mix and MBT are required in the standard series

Examining the Relationship between Tobacco Use and Perceptions of a New Tobacco-Free Campus Policy

The purpose of this study was to examine the perceptions of tobacco-free policy benefits and enforcement on a campus with a tobacco free policy. Young adults aged 18 to 24 have the highest rate of tobacco use compared with all other age groups in the United States, and are the most targeted by the tobacco industry. Experts recommend that smoke-free and tobacco-free areas are the most effective ways to reduce exposure to secondhand smoke and encourage cessation. Surveys were distributed on a campus three years after the implementation of the tobacco-free policy. The study included 198 participants (n=198) and 14% of the participants self-reported as tobacco-users. The results confirmed that students who use tobacco products do have a different perception of the tobacco-free campus policy

Durability of geopolymer concrete exposed to acidic environment – a review

Acids attack concrete by dissolving both hydrated and unhydrated cement compounds as well as calcareous aggregates and the subsequent chemical reaction forms water soluble calcium compounds which are then leached away. The aggressiveness of the reaction depends on the pH of the acidic medium and the types of salts formed. Concrete pipes made of ordinary portland cement (OPC) carrying sewage water have always the presence acidic solutions in it. They deteriorate and service life of the pipes is affected along with the increased maintenance costs and that process cause environmental impacts.  Geopolymer binders are novel binders that relies on alumina silicate rather calcium silicate bonds for structural integrity so they have been reported as being acid resistant. Those could be produced by the chemical action between alumino-silicate material such as fly ash(FA), granulated blast furnaces slag (GGBS), metakaoline or silica fume with alkaline solutions like sodium silicate or sodium hydroxide. Geopolymers show superior performance in terms of corrosion and fire resistance due to the absence of water and calcium in their structure.Utilisation of waste materials like FA and GGBS makes geopolymer    concrete (GPC) an environment friendly construction material. This review paper looks in to the effect of various acids such as sulphuric acid, acetic acid, nitric acids on durability properties of OPC specimens, GPC specimens and GPC composite specimens when immersed in acidic solutions for certain period. The performance of geopolymer is analysed by the visual inspection and studying the parameters like weight loss, loss in compressive strength and maximum depth of penetration. Keywords- Geopolymer concrete, Sodium hydroxide, sodium silicate, metakaoline, silica fume, alumina silicat