Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Population & Thin film. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Optical properties of the Indo-Asian haze layer over the tropical Indian Ocean

Abstract: [1] Multiwavelength backscatter and extinction profiling was performed with a unique aerosol Raman lidar at Hulhule (4� N, 73� E), Maldives, as part of the Indian Ocean Experiment (INDOEX) between February 1999 and March 2000. The Raman lidar allowed a direct determination of the volume extinction coefficient of the particles at 355 and 532 nm at ambient conditions. Heavily polluted air masses from the Asian continent passed over the Maldives during the northeast monsoon seasons. The mean 532-nm particle optical depth was about 0.3; maximum values of 0.7 were measured. Above the polluted marine boundary layer, lofted plumes were found up to 4000-m height. On average, the freetropospheric aerosol layers contributed 30–60% to the particle optical depth. The volume extinction coefficient at 532 nm typically ranged from 25 to 175 Mm � 1 in the elevated layers. The pollution plumes are characterized separately for the air masses from Southeast Asia, North India, and South India. The analysis includes backward trajectories and emission inventory data for India. The extinction-to-backscatter ratio (lidar ratio) at 532 nm was mostly between 30 and 100 sr, and accumulated at 50–80 sr for highly absorbing particles from northern India. The shift of the lidar-ratio distribution for northern Indian aerosols by about 20 sr toward larger values compared to European values is consistent

Structured learning for non-smooth ranking losses

Abstract: Learning to rank from relevance judgment is an active research area. Itemwise score regression, pairwise preference satisfaction, and listwise structured learning are the major techniques in use. Listwise structured learning has been applied recently to optimize important non-decomposable ranking criteria like AUC (area under ROC curve) and MAP (mean average precision). We propose new, almost-linear-time algorithms to optimize for two other criteria widely used to evaluate search systems: MRR (mean reciprocal rank) and NDCG (normalized discounted cumulative gain) in the max-margin structured learning framework. We also demonstrate that, for different ranking criteria, one may need to use different feature maps. Search applications should not be optimized in favor of a single criterion, because they need to cater to a variety of queries. E.g., MRR is best for navigational queries, while NDCG is best for informational queries. A key contribution of this paper is to fold multiple ranking loss functions into a multi-criteria max-margin optimization. The result is a single, robust ranking model that is close to the best accuracy of learners trained on individual criteria. In fact, experiments over the popular LETOR and TREC data sets show that, contrary to conventional wisdom, a test criterion is often not best served by training with the same individual criterion.

Reviewing the relationship between human resource practices and psychological contract and their impact on employee attitude and behaviours: A conceptual model

Abstract: Purpose – The purpose of this paper is to review and synthesise literature on the role of human resource practices (HRP) in shaping employee psychological contract (PC). Based on this review, a conceptual framework for examining the relationship between HRP and PC and their impact on employee attitudes as well as behaviour has been put forward for further examination.Design/methodological/approach – An extensive review of the literature, examining the role of HRP in influencing PC of employees, between the periods 1972 to 2007 has been conducted. Adopting the multi‐level approach, the paper discusses the role of individual variable (PC) and organisational variable (HRP) on employee attitudes and behaviours.Findings – The review brings to fore the following: the role of business and employment relationship strategy on HRP; the relationship between HRP and organisation culture as well as employees attitudes and behaviours; the relationship between HRP on and employee's psychological contract; and the modera...