Treatment of dry eye: An analysis of the British Sjögren's Syndrome Association comparing substitute tear viscosity and subjective efficacy

Purpose

This study aims to address the lack of independent subjective efficacy data on artificial tear substitutes in the treatment of dry eye due to the anecdotal association of ‘thicker’ products being more effective.

Methods

This is an independent study of the subjective use and efficacy of topical treatments used by members of the British Sjögren's Syndrome Association (BSSA) related to product viscosity. 2000 members of the BSSA were sent a questionnaire regarding their physical condition and the use of artificial tear substitutes. Viscosity analysis was performed on the most popular preparations. Statistical comparison is made between subjective efficacies related to substitute tear viscosity.

Results

1088 patients responded giving information regarding their condition together with the subjective use and efficacy data of artificial tear substitutes. Visco-analysis was performed on the most popular preparations; these had more than 50 patients using them. In terms of subjective benefits related to viscosity for ‘frequency’ and ‘duration’ the data suggests a general trend toward viscous preparations being instilled less frequently and lasting longer; however this was not shown to be significantly correlated and some interesting comparisons are reported.

Conclusions

The results confirm high levels of ocular lubricant use in the BSSA population. Our data investigates the often-anecdotal evidence that thicker preparations are more effective. However, we did not find this correlation to be statistically significant suggesting further study into factors related to subjective product efficacy. These results lay foundations for the development of future products in the treatment of severe dry eye.     

Experimental and computational investigation into suppressing natural convection in chilled ceiling/displacement ventilation environments

The combination of chilled ceiling and displacement ventilation systems can cause destruction of the displacement flow pattern in some circumstances. This paper reports on the performance of a new technique for achieving stable conditions for displacement airflow in the presence of a chilled ceiling system. The technique is based on the attachment of a honeycomb slat system to the underside of a chilled ceiling, thereby suppressing downward cool natural convection. Investigations were carried out using both computational and experimental methods for a range of typical office environment conditions. The results showed that a slat depth to width ratio of 10 could suppress the natural convection by more than 80% when the Rayleigh number reached 7 × 10⁶. This confirms that the technique is capable of minimising downward cool air currents, resulting in preservation of the displacement flow pattern in the presence of the chilled ceiling. The proposed slat system can raise the general air temperature in the space allowing some displacement flow pattern to occur. The outcome of this study is the emergence of a honeycomb slat-based approach for improving the performance, together with provision of general advice for designers as regards the combination of radiant cooling/displacement ventilation systems.     

Heat transfer enhancement of finned-tube heat exchanger using nozzle- and diffuser-shaped fins instead of straight fins

In this paper, a new method has been used to improve the heat transfer rate in the finned-tube heat exchanger with nozzle- and diffuser-shaped arrangement. For this study, the effect of several parameters was studied numerically. For the computational fluid dynamics simulation, the continuity, momentum, and energy equations were solved by the finite volume method using the standard k–ԑ model. The rate of heat transfer increases with the decreasing of fin bend radius (15 < R_fb < 20) for both nozzle-shaped fin and diffuser-shaped fin. By increasing of side temperature (600 < T_side < 900) and side Reynolds number (2000 < Re_side < 5000) the heat transfer rate increased for both nozzle- and diffuser-shaped fins. Results showed that a nozzle-shaped fin with a fin bend radius of 15 mm under the condition of Re_in = 20,000, T_side = 900 K, and Re_side = 3400 has a higher effect on heat transfer in comparison with the other types of fins. The maximum heat transfer rate was almost 39% and 35% for the nozzle-shaped fin with a bend radius of 15 mm and diffuser-shaped fin with a bend radius of 15 mm compared with the simple tube, respectively. Finally, correlational equations have been suggested to forecast the average Nu number as functions of various parameters of the tube equipped with different types of outer fins involving nozzle- and diffuser-shaped.     

Offshore Software Maintenance Outsourcing Process Model Validation: A Case Study Approach

The successful execution and management of Offshore Software Maintenance Outsourcing (OSMO) can be very beneficial for OSMO vendors and the OSMO client. Although a lot of research on software outsourcing is going on, most of the existing literature on offshore outsourcing deals with the outsourcing of software development only. Several frameworks have been developed focusing on guiding software system managers concerning offshore software outsourcing. However, none of these studies delivered comprehensive guidelines for managing the whole process of OSMO. There is a considerable lack of research working on managing OSMO from a vendor’s perspective. Therefore, to find the best practices for managing an OSMO process, it is necessary to further investigate such complex and multifaceted phenomena from the vendor’s perspective. This study validated the preliminary OSMO process model via a case study research approach. The results showed that the OSMO process model is applicable in an industrial setting with few changes. The industrial data collected during the case study enabled this paper to extend the preliminary OSMO process model. The refined version of the OSMO process model has four major phases including (i) Project Assessment, (ii) SLA (iii) Execution, and (iv) Risk.