University of Toronto

About: University of Toronto is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 126067 authors who have published 294940 publications receiving 13536856 citations. The organization is also known as: UToronto & U of T.

Non-Interactive Zero-Knowledge Proof of Knowledge and Chosen Ciphertext Attack

Abstract: The zero-knowledge proof of knowledge, first denned by Fiat, Fiege and Shamir, was used by Galil, Haber and Yung as a means of constructing (out of a trapdoor function) an interactive public-key cryptosystem provably secure against chosen ciphertext attack. We introduce a revised setting which permits the definition of a non-interactive analogue, the non-interactive zero-knowledge proof of knowledge, and show how it may be constructed in that setting from a non-interactive zero-knowledge proof system for NP (of the type introduced by Blum, Feldman and Micali). We give a formalization of chosen ciphertext attack in our model which is stronger than the "lunchtime attack" considered by Naor and Yung, and prove a non-interactive public-key cryptosystem based on non-interactive zero-knowledge proof of knowledge to be secure against it.

The immediate psychological and occupational impact of the 2003 SARS outbreak in a teaching hospital

Abstract: Background: The outbreak of severe acute respiratory syndrome (SARS) in Toronto, which began on Mar. 7, 2003, resulted in extraordinary public health and infection control measures. We aimed to describe the psychological and occupational impact of this event within a large hospital in the first 4 weeks of the outbreak and the subsequent administrative and mental health response. Methods: Two principal authors met with core team members and mental health care providers at Mount Sinai Hospital, Toronto, to compile retrospectively descriptions of the experiences of staff and patients based on informal observation. All authors reviewed and analyzed the descriptions in an iterative process between Apr. 3 and Apr. 13, 2003. Results: In a 4-week period, 19 individuals developed SARS, including 11 health care workers. The hospital’s response included establishing a leadership command team and a SARS isolation unit, implementing mental health support interventions for patients and staff, overcoming problems with logistics and communication, and overcoming resistance to directives. Patients with SARS reported fear, loneliness, boredom and anger, and they worried about the effects of quarantine and contagion on family members and friends. They experienced anxiety about fever and the effects of insomnia. Staff were adversely affected by fear of contagion and of infecting family, friends and colleagues. Caring for health care workers as patients and colleagues was emotionally difficult. Uncertainty and stigmatization were prominent themes for both staff and patients. Interpretation: The hospital’s response required clear communication, sensitivity to individual responses to stress, collaboration between disciplines, authoritative leadership and provision of relevant support. The emotional and behavioural reactions of patients and staff are understood to be a normal, adaptive response to stress in the face of an overwhelming event.

Early infancy microbial and metabolic alterations affect risk of childhood asthma

Abstract: Asthma is the most prevalent pediatric chronic disease and affects more than 300 million people worldwide. Recent evidence in mice has identified a "critical window" early in life where gut microbial changes (dysbiosis) are most influential in experimental asthma. However, current research has yet to establish whether these changes precede or are involved in human asthma. We compared the gut microbiota of 319 subjects enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) Study, and show that infants at risk of asthma exhibited transient gut microbial dysbiosis during the first 100 days of life. The relative abundance of the bacterial genera Lachnospira, Veillonella, Faecalibacterium, and Rothia was significantly decreased in children at risk of asthma. This reduction in bacterial taxa was accompanied by reduced levels of fecal acetate and dysregulation of enterohepatic metabolites. Inoculation of germ-free mice with these four bacterial taxa ameliorated airway inflammation in their adult progeny, demonstrating a causal role of these bacterial taxa in averting asthma development. These results enhance the potential for future microbe-based diagnostics and therapies, potentially in the form of probiotics, to prevent the development of asthma and other related allergic diseases in children.

The Apache Point Observatory Galactic Evolution Experiment (APOGEE)

Abstract: National Science Foundation [AST-1109178, AST-1616636]; Gemini Observatory; Spanish Ministry of Economy and Competitiveness [AYA-2011-27754]; NASA [NNX12AE17G]; Hungarian Academy of Sciences; Hungarian NKFI of the Hungarian National Research, Development and Innovation Office [K-119517]; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science

Clock-drawing: is it the ideal cognitive screening test?

Abstract: Objective. The clock-drawing test has achieved widespread clinical use in recent years as a cognitive screening instrument and a significant amount of literature relates to its psychometric properties and clinical utility. This review aims to synthesize the available evidence and assess the value of this screening test according to well-defined criteria. Design. A Medline and Psycho-info literature search of all languages was done from 1983 to 1998 including manual cross-referencing of bibliographies. A brief summary of all original scoring systems is provided as well as a review of replication studies. Psychometric data including correlations with other cognitive tests were recorded. Qualitative aspects of the test are also described. Results. Among published studies, the mean sensitivity (85%) and specificity (85%) of the clock-drawing test are impressive. Correlations with the Mini-Mental State Examination and other cognitive tests was high, generally greater than r = 0.5. High levels of inter-rater and test–re-test reliability and positive predictive value are recorded and despite significant variability in the scoring systems, all report similar psychometric properties. The clock test also shows a sensitivity to cognitive change with good predictive validity. Conclusions. The clock-drawing test meets defined criteria for a cognitive screening instrument. It taps into a wide range of cognitive abilities including executive functions, is quick and easy to administer and score with excellent acceptability by subjects. Together with informant reports, the clock-drawing test is complementary to the widely used and validated Mini-Mental State Examination and should provide a significant advance in the early detection of dementia and in monitoring cognitive change. A simple scoring system with emphasis on the qualitative aspects of clock-drawing should maximize its utility. Copyright © 2000 John Wiley & Sons, Ltd.