On the Robustness of Randomized Ensembles to Adversarial Perturbations

Randomized ensemble classifiers (RECs), where one classifier is randomly selected during inference, have emerged as an attractive alternative to traditional ensembling methods for realizing adversarially robust classifiers with limited compute requirements. However, recent works have shown that existing methods for constructing RECs are more vulnerable than initially claimed, casting major doubts on their efficacy and prompting fundamental questions such as: "When are RECs useful?", "What are their limits?", and "How do we train them?". In this work, we first demystify RECs as we derive fundamental results regarding their theoretical limits, necessary and sufficient conditions for them to be useful, and more. Leveraging this new understanding, we propose a new boosting algorithm (BARRE) for training robust RECs, and empirically demonstrate its effectiveness at defending against strong $\ell_\infty$ norm-bounded adversaries across various network architectures and datasets. Our code can be found at https://github.com/hsndbk4/BARRE.Comment: Published as a conference paper in ICML 202

Members of opposite sex mutually regulate gonadal recrudescence in the lizard Calotes versicolor (Agamidae)

Adult males and females of the seasonally breeding lizard Calotes versicolor were subjected to various social situations under semi-natural conditions to explain the role of socio-sexual factors in gonadal recrudescence. They were grouped as: (i) males and females, (ii) males and females separated by a wire mesh, (iii) same sex groups of males or females, (iv) castrated males with intact females and (v) ovariectomized (OvX) females with intact males from postbreeding to breeding phase. Specimens collected from the wild during breeding season served as the control group. Plasma sex steroid levels (testosterone in male and 17β-estradiol in female), spermatogenetic activity and vitellogenesis were the criteria to judge gonadal recrudescence. In intact males and females that were kept together, gonadal recrudescence and plasma sex steroids levels were comparable to those in wild-caught individuals. Gonadal recrudescence was at its least in all male and all female groups, and plasma sex steroids were at basal levels. Association with OvX females initiated testicular recrudescence but spermatogenetic activity progressed only up to the spermatid stage while males separated from females by wire mesh showed spermatogenetic activity for a shorter period. Females grouped with castrated males and those separated from males by wire mesh produced vitellogenic follicles. However, the total number and diameter of vitellogenic follicles, and plasma estradiol levels were lower than in the females grouped with intact males. The findings indicate that association with members of the opposite sex with progressively rising titers of sex steroids is crucial in both initiating and sustaining gonadal recrudescence in the lizard. Thus, members of the opposite sex mutually regulate gonadal recrudescence in the C. versicolor

AdaptDB: Adaptive Partitioning for Distributed Joins

Big data analytics often involves complex join queries over two or more tables. Such join processing is expensive in a distributed setting both because large amounts of data must be read from disk, and because of data shuffling across the network. Many techniques based on data partitioning have been proposed to reduce the amount of data that must be accessed, often focusing on finding the best partitioning scheme for a particular workload, rather than adapting to changes in the workload over time. In this paper, we present AdaptDB, an adaptive storage manager for analytical database workloads in a distributed setting. It works by partitioning datasets across a cluster and incrementally refining data partitioning as queries are run. AdaptDB introduces a novel hyper-join that avoids expensive data shuffling by identifying storage blocks of the joining tables that overlap on the join attribute, and only joining those blocks. Hyper-join performs well when each block in one table overlaps with few blocks in the other table, since that will minimize the number of blocks that have to be accessed. To minimize the number of overlapping blocks for common join queries, AdaptDB users smooth repartitioning to repartition small portions of the tables on join attributes as queries run. A prototype of AdaptDB running on top of Spark improves query performance by 2-3x on TPC-H as well as real-world dataset, versus a system that employs scans and shuffle-joins

Drug prescribing pattern in ulcerative colitis in a tertiary care hospital: an observational study

Background: Ulcerative colitis (UC) is an inflammatory disease of colon and rectum of uncertain etiology. The clinical course of UC is marked by exacerbations and remissions. Furthermore there is limited data available on the management of ulcerative colitis from India. Hence, the present study was undertaken to study the drug prescribing pattern in ulcerative colitis.Methods: A retrospective case record based observational study was done at Kasturba Hospital, Manipal, India from 1st January 2009 to 31st December 2010. Patients diagnosed to have UC during our study period based on clinical, endoscopic and histopathological evidence were included in the study. SPSS 17 software package was used for statistical calculations. Descriptive statistics was used to analyze the data.Results: The total number of patients diagnosed to have UC during our study period was 83.The peak incidence of disease was in the age group of 30-39 years and it was more common in males. The prescription rate of aminosalicylates, glucocorticoids and immunosuppressants were 96.3, 54.3, and 18.5% respectively. Mesalamine, prednisolone, and azathioprine were the commonly prescribed drugs in each class. The commonly prescribed treatment regimen was combination of aminosalicylates with glucocorticoids (43.2%).Conclusions: Ulcerative colitis was more common in males. Aminosalicylates were the commonly prescribed drugs and a combination of aminosalicylate and steroid was frequently used regimen in our study

Termite and Ecosystem Processes: A Study from Western Ghats, South India

Termites are undoubtedly key soil organisms in tropical and subtropical soils. They greatly influence the physical, chemical, biological properties of soils and, consequently, water dynamics hence well known as “soil engineers”. Their effect on the ecosystem can be appreciated only if we have the detailed knowledge about the process and functions carried out by them in the tropical soil. Some studies from Africa and Vietnam gave a glimpse of services provided by the termite and under that particular vegetation but under Indian context, no such studies were conducted as result we don’t have much data regarding their effect on soil properties, water infiltration and vice versa. Hence, field studies were carried out to understand the effect of termite activity and the ecological benefits derived in terms of soil dynamics and water infiltration.The study was conducted at Uttara Kannada district located at the lavishing western ghat. Mound building termite species Odontotermes obesus, was considered as study species as it is the widespread and dominant termite species of the Indo-oriental region. Numerical density, mound height and soil properties of O. obesus mounds were only analysed along with the neighbouring soil without termite activity in forest areas. To assess the influence of the vegetation on termite mound properties, the forest types were classified into plantations, evergreen, semi-evergreen or deciduous. In the forest, termite active sites, as well as sites devoid of termite activity, were selected and the rate of water infiltration in these sites was also measured using Beerkan method. Bulk density and water humidity were measured. Data obtained were analysed. Results revealed that the amount of rainfall defined termite mound abundance, and it has a remarkable influence on the density/height of termite mounds. In terms of soil properties, clay and C content in the soil which is known to bring the stability to the termite mounds did not show any significant relationship with density or height of the termite mound. But a positive linear relationship was observed between clay content in termite mound walls and that in the surrounding topsoil. The result of water infiltration studies at the sites showed that there was a significant variation in the rate of water infiltration in the termite active sites. The study presented here is the important one as it aims towards the efficient determination of the functional influence of soil biodiversity (termites) in tropical ecosystem functioning and a better evaluation of their impacts on soil erosion and water dynamic at the local and global scale. Moreover, the link between soil biodiversity and ecosystem services, such as water availability and quality, is often mentioned but rarely demonstrated. This paper is therefore original in its approach and in it quantifies the importance of biodiversity on soil erosion, water dynamic and quality in tropical ecosystems. There is a clear lack of information on the functional impact of termites on ecosystem functioning in India, in comparison with Africa where most of the studies have been carried out. This study aims to counterbalance this trend through this paper.Keywords: Termites, Soil and water dynamics, Water infiltratio