Amin Ahsan Ali

mPuff: automated detection of cigarette smoking puffs from respiration measurements

Smoking has been conclusively proved to be the leading cause of mortality that accounts for one in five deaths in the United States. Extensive research is conducted on developing effective smoking cessation programs. Most smoking cessation programs achieve low success rate because they are unable to intervene at the right moment. Identification of high-risk situations that may lead an abstinent smoker to relapse involve discovering the associations among various contexts that precede a smoking session or a smoking lapse. In the absence of an automated method, detection of smoking events still relies on subject self-report that is prone to failure to report and involves subject burden. Automated detection of smoking events in the natural environment can revolutionize smoking research and lead to effective intervention. In this paper, we present mPuff a novel system to automatically detect smoking puffs from respiration measurements, using which a model can be developed to automatically detect entire smoking episodes in the field. We introduce several new features from respiration that can help classify individual respiration cycles into smoking puffs or non-puffs. We then propose supervised and semi-supervised support vector models to detect smoking puffs. We train our models on data collected from 10 daily smokers and find that smoking puffs can be detected with an accuracy of 91% within a smoking session. We then consider respiration measurements during confounding events such as stress, speaking, and walking, and show that our model can still identify smoking puffs with an accuracy of 86.7%. The smoking detector presented here opens the opportunity to develop effective interventions that can be delivered on a mobile phone when and where smoking urges may occur, thereby improving the abysmal low rate of success in smoking cessation.

puffMarker: a multi-sensor approach for pinpointing the timing of first lapse in smoking cessation

Recent researches have demonstrated the feasibility of detecting smoking from wearable sensors, but their performance on real-life smoking lapse detection is unknown. In this paper, we propose a new model and evaluate its performance on 61 newly abstinent smokers for detecting a first lapse. We use two wearable sensors --- breathing pattern from respiration and arm movements from 6-axis inertial sensors worn on wrists. In 10-fold cross-validation on 40 hours of training data from 6 daily smokers, our model achieves a recall rate of 96.9%, for a false positive rate of 1.1%. When our model is applied to 3 days of post-quit data from 32 lapsers, it correctly pinpoints the timing of first lapse in 28 participants. Only 2 false episodes are detected on 20 abstinent days of these participants. When tested on 84 abstinent days from 28 abstainers, the false episode per day is limited to 1/6.

mConverse: inferring conversation episodes from respiratory measurements collected in the field

Automated detection of social interactions in the natural environment has resulted in promising advances in organizational behavior, consumer behavior, and behavioral health. Progress, however, has been limited since the primary means of assessing social interactions today (i.e., audio recording) has several issues in field usage such as microphone occlusion, lack of speaker specificity, and high energy drain, in addition to significant privacy concerns. In this paper, we present mConverse, a new mobile-based system to infer conversation episodes from respiration measurements collected in the field from an unobtrusively wearable respiratory inductive plethysmograph (RIP) band worn around the users chest. The measurements are wire-lessly transmitted to a mobile phone, where they are used in a novel machine learning model to determine whether the wearer is speaking, listening, or quiet. Our model incorporates several innovations to address issues that naturally arise in the noisy field environment such as confounding events, poor data quality due to sensor loosening and detachment, losses in the wireless channel, etc. Our basic model obtains 83% accuracy for the three class classification. We formulate a Hidden Markov Model to further improve the accuracy to 87%. Finally, we apply our model to data collected from 22 subjects who wore the sensor for 2 full days in the field to observe conversation behavior in daily life and find that people spend 25% of their day in conversations.

Are we there yet?: feasibility of continuous stress assessment via wireless physiological sensors

Stress can lead to headaches and fatigue, precipitate addictive behaviors (e.g., smoking, alcohol and drug use), and lead to cardiovascular diseases and cancer. Continuous assessment of stress from sensors can be used for timely delivery of a variety of interventions to reduce or avoid stress. We investigate the feasibility of continuous stress measurement via two field studies using wireless physiological sensors --- a four-week study with illicit drug users (n = 40), and a one-week study with daily smokers and social drinkers (n = 30). We find that 11+ hours/day of usable data can be obtained in a 4-week study. Significant learning effect is observed after the first week and data yield is seen to be increasing over time even in the fourth week. We propose a framework to analyze sensor data yield and find that losses in wireless channel is negligible; the main hurdle in further improving data yield is the attachment constraint. We show the feasibility of measuring stress minutes preceding events of interest and observe the sensor-derived stress to be rising prior to self-reported stress and smoking events.

Asynchronous leader election in mobile ad hoc networks

With the proliferation of portable computing platforms and small wireless devices, the classical dilemma of leader election in mobile ad hoc networks has received attention from the research community in recent years. The problem aims to elect a unique leader among mobile nodes regardless of their physical locations. But, existing distributed leader election algorithms do not cope with highly spontaneous nature of mobile ad hoc networks. This paper presents a consensus-based leader election algorithm that finds a local extrema among the nodes participating in leader election. The algorithm is highly adaptive with ad hoc networks in the sense that it can tolerate intermittent failures, such as link failures, sudden crash or recovery of mobile nodes, network partitions, and merging of connected network components associated with ad hoc networks. The paper also presents proofs of correctness to exhibit the fairness of this algorithm.

Identifying drug (cocaine) intake events from acute physiological response in the presence of free-living physical activity

A variety of health and behavioral states can potentially be inferred from physiological measurements that can now be collected in the natural free-living environment. The major challenge, however, is to develop computational models for automated detection of health events that can work reliably in the natural field environment. In this paper, we develop a physiologically-informed model to automatically detect drug (cocaine) use events in the free-living environment of participants from their electrocardiogram (ECG) measurements. The key to reliably detecting drug use events in the field is to incorporate the knowledge of autonomic nervous system (ANS) behavior in the model development so as to decompose the activation effect of cocaine from the natural recovery behavior of the parasympathetic nervous system (after an episode of physical activity). We collect 89 days of data from 9 active drug users in two residential lab environments and 922 days of data from 42 active drug users in the field environment, for a total of 11,283 hours. We develop a model that tracks the natural recovery by the parasympathetic nervous system and then estimates the dampening caused to the recovery by the activation of the sympathetic nervous system due to cocaine. We develop efficient methods to screen and clean the ECG time series data and extract candidate windows to assess for potential drug use. We then apply our model on the recovery segments from these windows. Our model achieves 100% true positive rate while keeping the false positive rate to 0.87/day over (9+ hours/day of) lab data and to 1.13/day over (11+ hours/day of) field data.

Continuous in-the-field measurement of heart rate: Correlates of drug use, craving, stress, and mood in polydrug users

BACKGROUND Ambulatory physiological monitoring could clarify antecedents and consequences of drug use and could contribute to a sensor-triggered mobile intervention that automatically detects behaviorally risky situations. Our goal was to show that such monitoring is feasible and can produce meaningful data. METHODS We assessed heart rate (HR) with AutoSense, a suite of biosensors that wirelessly transmits data to a smartphone, for up to 4 weeks in 40 polydrug users in opioid-agonist maintenance as they went about their daily lives. Participants also self-reported drug use, mood, and activities on electronic diaries. We compared HR with self-report using multilevel modeling (SAS Proc Mixed). RESULTS Compliance with AutoSense was good; the data yield from the wireless electrocardiographs was 85.7%. HR was higher when participants reported cocaine use than when they reported heroin use (F(2,9)=250.3, p<.0001) and was also higher as a function of the dose of cocaine reported (F(1,8)=207.7, p<.0001). HR was higher when participants reported craving heroin (F(1,16)=230.9, p<.0001) or cocaine (F(1,14)=157.2, p<.0001) than when they reported of not craving. HR was lower (p<.05) in randomly prompted entries in which participants reported feeling relaxed, feeling happy, or watching TV, and was higher when they reported feeling stressed, being hassled, or walking. CONCLUSIONS High-yield, high-quality heart-rate data can be obtained from drug users in their natural environment as they go about their daily lives, and the resultant data robustly reflect episodes of cocaine and heroin use and other mental and behavioral events of interest.

A consensus-based l -Exclusion algorithm for mobile ad hoc networks

This paper addresses the @?-Exclusion problem for mobile ad hoc networks. The @?-Exclusion problem, a generalization of distributed mutual exclusion problem, involves a group of processes, each of which intermittently requires access to one of @? identical resources or pieces of code called the critical section (CS). This paper presents a consensus-based mobility-aware @?-Exclusion (LE) algorithm that operates asynchronously and copes explicitly with arbitrary (possibly concurrent) topology changes associated with such networks. The algorithm can tolerate link changes or failures, sudden crashes or recoveries of at most @?-1 mobile nodes. The algorithm is based on collection of enough consensuses for a mobile node intending to enter CS, and uses diffusing computations for this purpose. This paper presents a simulation to demonstrate that the proposed algorithm, as compared to the k-Reverse Link (KRL) algorithm, is quite effective to variety of operating conditions, and is highly adaptive to frequent and unpredictable topology changes due to link changes or failures.

A technique for logic design of voltage-mode pass transistor based multi-valued multiple-output logic circuits

An approach for designing multi-valued logic circuits is proposed in this paper. We also describe a systematic method for implementing a set of binary logic functions, as multi-valued logic functions, and the heuristic algorithms for different stages of the design process are provided along with it. Experimental results are included for a number of benchmark functions and the proposed method has been found to be quite efficient, in terms of number of transistors, in the implementation of some of these functions. The proposed circuits are essentially voltage-mode circuits with multi-valued outputs and in the case of implementing multiple-output binary logic functions this approach produces circuits with reduced number of output pins. The circuits described here are also suitable to be implemented in VLSI technology since they are composed of simple enhancement/depletion mode MOS transistors and pass transistors.

Fish activity tracking and species identification in underwater video

In this paper we propose an automatic marine life monitoring system. First task in the monitoring process is to detect underwater moving objects as fishes. Second Task is to identify the species of the detected fish. Third task is to track the detected fish to avoid multiple counting and record their activities. Detection is performed using GMM based background subtraction method, classification is performed using Pyramid Histogram Of visual Words (PHOW) features with SVM classifier and finally identified fishes are tracked using “Kalman Filter”. This experiment is performed using data-set from the CLEF 2015. The proposed system can detect and track fishes with 48.94 percent accuracy in videos, and it can identify fishes in high resolution still image with 91.7 percent accuracy where as in the low quality video fishes are detected with 40.1 percent accuracy.