Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

Blood-vessel closure using photosensitizers engineered for two-photon excitation

Abstract: The spatial control of optical absorption provided by two-photon excitation has led to tremendous advances in microscopy1 and microfabrication2. Medical applications of two-photon excitation in photodynamic therapy3,4 have been widely suggested5,6,7,8,9,10,11,12,13,14,15,16,17,18, but thus far have been rendered impractical by the low two-photon cross-sections of photosensitizer drugs (which are compounds taken up by living tissues that become toxic on absorption of light). The invention of efficient two-photon activated drugs will allow precise three-dimensional manipulation of treatment volumes, providing a level of targeting unattainable with current therapeutic techniques. Here we present a new family of photodynamic therapy drugs designed for efficient two-photon excitation and use one of them to demonstrate selective closure of blood vessels through two-photon excitation photodynamic therapy in vivo. These conjugated porphyrin dimers have two-photon cross-sections that are more than two orders of magnitude greater than those of standard clinical photosensitizers17. This is the first demonstration of in vivo photodynamic therapy using a photosensitizer engineered for efficient two-photon excitation. Two-photon excitation is attractive for photodynamic therapy as it potentially allows deeper penetration within biological tissue and targeting with better precision. However, two-photon cross-sections of light-sensitive drugs are typically small, which has until now limited their practical utility. Now Anderson and colleagues have come up with a new family of light-sensitive drugs that are designed for efficient two-photon excitation. They demonstrate selective closure of blood vessels in mice using one of their new drugs.

Recommender systems in e-commerce

Abstract: Internet is speeding up and modifying the manner in which daily tasks such as online shopping, paying utility bills, watching new movies, communicating, etc., are accomplished. As an example, in older shopping methods, products were mass produced for a single market and audience but that approach is no longer viable. Markets based on long product and development cycles can no longer survive. To stay competitive, markets need to provide different products and services to different customers with different needs. The shift to online shopping has made it incumbent on producers and retailers to customize for customers' needs while providing more options than were possible before. This, however, poses a problem for customers who must now analyze every offering in order to determine what they actually need and will benefit from. To aid customers in this scenario, we discuss about common recommender systems techniques that have been employed and their associated trade-offs.