Systems Engineering on the James Webb Space Telescope

The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2014. System-level verification of critical performance requirements will rely on integrated observatory models that predict the wavefront error accurately enough to verify that allocated top-level wavefront error of 150 nm root-mean-squared (rms) through to the wave-front sensor focal plane is met. This paper describes the systems engineering approach used on the JWST through the detailed design phase

ADVANCEMENTS IN CONTROLLED RELEASE GASTRORETENTIVE DRUG DELIVERY SYSTEM: A REVIEW

Oral delivery of the drug is by far the most preferable route of drug delivery due to the ease of administration, patient compliance and flexibility in the formulations  but has a drawback of non-site specificity and short gastric resident time. In order to overcome the drawbacks of conventional oral drug delivery systems, several technical advancements have led to the development of gastro retentive  drug delivery system that could revolutionize method of medication and provide a number of therapeutic benefits. In order to understand various physiological difficulties to achieve gastric retention, we have summarized important factors controlling gastric retention. Afterwards, we have reviewed various gastroretentive approaches designed and developed until now, i.e. floating drug delivery system(FDDS), bio- or mucoadhesive system, expandable, unfoldable system, high density system, raft forming system, super porous hydrogel system and magnetic systems. Among these systems, FDDS have been most commonly used. Finally, advantages, disadvantages, evaluation, marketed preparation and future potential  of gastro retentive drug delivery systems were covere

NOVEL INSITU POLYMERIC DRUG DELIVERY SYSTEM: A REVIEW

In situ forming polymeric formulations are drug delivery systems that are in sol form before administration in the body, but once administered, undergo gelation in situ, to form a gel. The formation of gels depends on factors like temperature modulation, pH change, presence of ions and ultra violet irradiation, electrical sensitivity, enzyme sensitive from which the drug gets released in a sustained and controlled manner. Routes of administration are oral, ocular, rectal, vaginal, injectable and intraperitoneal. Various biodegradable polymers that are used for the formulation of in situ gels include gellan gum, alginic acid, xyloglucan, pectin, chitosan, poly (DL lactic acid), poly (DL-lactide-co-glycolide) and poly-caprolactone. The in situ gel forming polymeric formulations offer several advantages like sustained and prolonged action in comparison to conventional drug delivery systems and good patient compliance, good stability and biocompatibility characteristics make the in situ gel dosage forms very reliable. Evaluation of In situ gel systems include in vitro drug release studies, sol-gel transition temperature and gelling time, gel strength, viscosity & rheology, texture analysis, clarity. Commercial formulations of in situ polymeric systems are Regel Depot Technology, Cytoryn and Timoptic-Xe. Recent developments in the field of polymer science and technology has led to the development of various stimuli sensitive hydrogels like pH, temperature sensitive, which are used for the targeted delivery of proteins to colon, and chemotherapeutic agents to tumors. Sustained and prolonged release of the drug, good stability and biocompatibility characteristics make the in situ gel dosage forms very reliable. From a manufacturing point of view, the production of such devices is less complex and thus lowers the investment and manufacturing.   KEYWORDS: Biodegradable polymers, polymeric gel, controlled release, in situ gels, poly (lactic-co-glycolic acid), sustained release

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure