Temporal Alignment of Dual Monitor Accelerometry Recordings

Combining accelerometry from multiple independent activity monitors worn by the same subject have gained widespread interest with the assessment of physical activity behavior. However, a difference in the real time clock accuracy of the activity monitor introduces a substantial temporal misalignment with long duration recordings which is commonly not considered. In this study, a novel method not requiring human interaction is described for the temporal alignment of triaxial acceleration measured with two independent activity monitors and evaluating the performance with the misalignment manually identified. The method was evaluated with free-living recordings using both combined wrist/hip (n = 9) and thigh/hip device (n = 30) wear locations, and descriptive data on initial offset and accumulated day 7 drift in a large-scale population-based study (n = 2513) were calculated. The results from the Bland–Altman analysis show good agreement between the proposed algorithm and the reference suggesting that the described method is valid for reducing the temporal misalignment and thus reduce the measurement error with aggregated data. Applying the algorithm to the n = 2513 samples worn for 7-days suggest a wide and substantial issue with drift over time when each subject wears two independent activity monitors.

Synchronous facial action binds dynamic facial features

We asked how dynamic facial features are perceptually grouped. To address this question, we varied the timing of mouth movements relative to eyebrow movements, while measuring the detectability of a small temporal misalignment between a pair of oscillating eyebrows—an eyebrow wave. We found eyebrow wave detection performance was worse for synchronous movements of the eyebrows and mouth. Subsequently, we found this effect was specific to stimuli presented to the right visual field, implicating the involvement of left lateralised visual speech areas. Adaptation has been used as a tool in low-level vision to establish the presence of separable visual channels. Adaptation to moving eyebrows and mouths with various relative timings reduced eyebrow wave detection but only when the adapting mouth and eyebrows moved asynchronously. Inverting the face led to a greater reduction in detection after adaptation particularly for asynchronous facial motion at test. We conclude that synchronous motion binds dynamic facial features whereas asynchronous motion releases them, allowing adaptation to impair eyebrow wave detection.

Realized and potential efficiency for post-stratified estimation in a national forest inventory

Post-stratification is often used to increase the precision of estimates arising from large-area forest inventories with plots established at permanent locations. Remotely sensed data and associated spatial products are often used for developing the post-stratification, which offers a mechanism to increase precision for less cost than increasing the sample size. While important variance reductions have been shown from post-stratification, it remains unknown where observed gains lie along the continuum of possible gains. This information is needed to determine whether efforts to further improve post-stratification outcomes are warranted. In this study, two types of ‘optimal’ post-stratification were compared to typical production-based post-stratifications to estimate the magnitude of remaining gains possible. Although the ‘optimal’ post-stratifications were derived using methods inappropriate for operational usage, the results indicated that substantial further increases in precision for estimates of both forest area and total tree biomass could be obtained with better post-stratifications. The potential gains differed by the attribute being estimated, the population being studied, and the number of strata. Practitioners seeking to optimize post-stratification face challenges such as evaluation of numerous auxiliary data sources, temporal misalignment between plot observations and remotely sensed data acquisition, and spatial misalignment between plot locations and remotely sensed data due to positional errors in both data types.

Getting Ahead of Time—Performing Temporal Boundaries to Coordinate Routines under Temporal Uncertainty

In this ethnographic study of firefighters we explore how routines are coordinated under high levels of temporal uncertainty—when the timing of critical events cannot be known in advance and temporal misalignment creates substantial risks. Such conditions render time-consuming incremental and situated forms of temporal structuring—the focus of previous research on temporal coordination—unfeasible. Our findings show that firefighters focused their efforts on enacting temporal autonomy or, as they called it, “getting ahead of time.” They gained temporal autonomy—the capacity to temporally uncouple from the unfolding situation to preserve the ability to adapt to autonomously selected events—by relying on rhythms they developed during training in performing individual routines and by opening up to the evolving situation only when transitioning between routines. Our study contributes to literature on temporal structuring by introducing temporal autonomy as a novel strategy for dealing with temporal contingencies. We also contribute to research on routine dynamics by introducing the performance of temporal boundaries as a previously unrecognized form of coordination within and among routines. Finally, we contribute to process research a method that allows analyzing complex temporal patterns and thus provides a novel way of visualizing processes.

La France à l’heure anglaise

During the Second World War, Germany often imposed its own time zone onto those countries it occupied. Chapter 5 looks at the case of France, and examines responses to a perceived temporal misalignment with Britain which occurred with its capitulation to Germany in June 1940. Surveying a series of wartime propaganda films, including those by the GPO Film Unit, the chapter demonstrates how war time was expressed through pastoral tropes, and through notions of Allied temporal guardianship. It turns to the activist writer Storm Jameson, whose novel Cloudless May (1943) conveys a kind of ‘international regionalism’ to cultivate British support for France. Through affective, embodied landscapes, she reinforces what she sees as modernism’s strengths, and revises what she sees as its weaknesses, for a geopolitical agenda.

Adversarial Cross-Domain Action Recognition with Co-Attention

Action recognition has been a widely studied topic with a heavy focus on supervised learning involving sufficient labeled videos. However, the problem of cross-domain action recognition, where training and testing videos are drawn from different underlying distributions, remains largely under-explored. Previous methods directly employ techniques for cross-domain image recognition, which tend to suffer from the severe temporal misalignment problem. This paper proposes a Temporal Co-attention Network (TCoN), which matches the distributions of temporally aligned action features between source and target domains using a novel cross-domain co-attention mechanism. Experimental results on three cross-domain action recognition datasets demonstrate that TCoN improves both previous single-domain and cross-domain methods significantly under the cross-domain setting.

Improved Temporal Calibration of Tracked Ultrasound: An Open-Source Solution

In tracked ultrasound systems, temporal misalignment between image and tracker data results in incorrect image pose. We present a fully automatic temporal calibration. We image a flat plate in water with a tracked probe undergoing periodic uniaxial freehand translation. Using robust line detection scheme, we compute temporal misalignment as difference between probe and corresponding image position. From 240 sequences, standard deviation was under 5 ms for standard imaging parameters. Source code is available in Public Library for Ultrasound Research, PLUS ( www.plustoolkit.org ).