175 research outputs found
Action Search: Spotting Actions in Videos and Its Application to Temporal Action Localization
State-of-the-art temporal action detectors inefficiently search the entire
video for specific actions. Despite the encouraging progress these methods
achieve, it is crucial to design automated approaches that only explore parts
of the video which are the most relevant to the actions being searched for. To
address this need, we propose the new problem of action spotting in video,
which we define as finding a specific action in a video while observing a small
portion of that video. Inspired by the observation that humans are extremely
efficient and accurate in spotting and finding action instances in video, we
propose Action Search, a novel Recurrent Neural Network approach that mimics
the way humans spot actions. Moreover, to address the absence of data recording
the behavior of human annotators, we put forward the Human Searches dataset,
which compiles the search sequences employed by human annotators spotting
actions in the AVA and THUMOS14 datasets. We consider temporal action
localization as an application of the action spotting problem. Experiments on
the THUMOS14 dataset reveal that our model is not only able to explore the
video efficiently (observing on average 17.3% of the video) but it also
accurately finds human activities with 30.8% mAP.Comment: Accepted to ECCV 201
Temporal Relational Reasoning in Videos
Temporal relational reasoning, the ability to link meaningful transformations
of objects or entities over time, is a fundamental property of intelligent
species. In this paper, we introduce an effective and interpretable network
module, the Temporal Relation Network (TRN), designed to learn and reason about
temporal dependencies between video frames at multiple time scales. We evaluate
TRN-equipped networks on activity recognition tasks using three recent video
datasets - Something-Something, Jester, and Charades - which fundamentally
depend on temporal relational reasoning. Our results demonstrate that the
proposed TRN gives convolutional neural networks a remarkable capacity to
discover temporal relations in videos. Through only sparsely sampled video
frames, TRN-equipped networks can accurately predict human-object interactions
in the Something-Something dataset and identify various human gestures on the
Jester dataset with very competitive performance. TRN-equipped networks also
outperform two-stream networks and 3D convolution networks in recognizing daily
activities in the Charades dataset. Further analyses show that the models learn
intuitive and interpretable visual common sense knowledge in videos.Comment: camera-ready version for ECCV'1
In-Home Daily-Life Captioning Using Radio Signals
This paper aims to caption daily life --i.e., to create a textual description
of people's activities and interactions with objects in their homes. Addressing
this problem requires novel methods beyond traditional video captioning, as
most people would have privacy concerns about deploying cameras throughout
their homes. We introduce RF-Diary, a new model for captioning daily life by
analyzing the privacy-preserving radio signal in the home with the home's
floormap. RF-Diary can further observe and caption people's life through walls
and occlusions and in dark settings. In designing RF-Diary, we exploit the
ability of radio signals to capture people's 3D dynamics, and use the floormap
to help the model learn people's interactions with objects. We also use a
multi-modal feature alignment training scheme that leverages existing
video-based captioning datasets to improve the performance of our radio-based
captioning model. Extensive experimental results demonstrate that RF-Diary
generates accurate captions under visible conditions. It also sustains its good
performance in dark or occluded settings, where video-based captioning
approaches fail to generate meaningful captions. For more information, please
visit our project webpage: http://rf-diary.csail.mit.eduComment: ECCV 2020. The first two authors contributed equally to this pape
Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii
Background: The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Methodology/Principal Findings: Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250uC hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. Conclusions/Significance: This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius an
Mixing of rhyolite, trachyte and basalt magma erupted from a vertically and laterally zoned reservoir, composite flow P1, Gran Canaria
The 14.1 Ma composite welded ignimbrite P1 (45 km3 DRE) on Gran Canaria is compositionally zoned from a felsic lower part to a basaltic top. It is composed of four component magmas mixed in vertically varying proportions: (1) Na-rhyolite (10 km3) zoned from crystal-poor to highly phyric; (2) a continuously zoned, evolved trachyte to sodic trachyandesite magma group (6 km3); (3) a minor fraction of Na-poor trachyandesite (<1 km3); and (4) nearly aphyric basalt (26 km3) zoned from 4.3 to 5.2 wt% MgO. We distinguish three sites and phases of mixing: (a) Mutual mineral inclusions show that mixing between trachytic and rhyolitic magmas occurred during early stages of their intratelluric crystallization, providing evidence for long-term residence in a common reservoir prior to eruption. This first phase of mixing was retarded by increasing viscosity of the rhyolite magma upon massive anorthoclase precipitation and accumulation. (b) All component magmas probably erupted through a ring-fissure from a common upper-crustal reservoir into which the basalt intruded during eruption. The second phase of mixing occurred during simultaneous withdrawal of magmas from the chamber and ascent through the conduit. The overall withdrawal and mixing pattern evolved in response to pre-eruptive chamber zonation and density and viscosity relationships among the magmas. Minor sectorial variations around the caldera reflect both varying configurations at the conduit entrance and unsteady discharge. (c) During each eruptive pulse, fragmentation and particulate transport in the vent and as pyroclastic flows caused additional mixing by reducing the length scale of heterogeneities. Based on considerations of magma density changes during crystallization, magma temperature constraints, and the pattern of withdrawal during eruption, we propose that eruption tapped the P1 magma chamber during a transient state of concentric zonation, which had resulted from destruction of a formerly layered zonation in order to maintain gravitational equilibrium. Our model of magma chamber zonation at the time of eruption envisages a basal high-density Na-poor trachyandesite layer that was overlain by a central mass of highly phyric rhyolite magma mantled by a sheath of vertically zoned trachyte-trachyandesite magma along the chamber walls. A conventional model of vertically stacked horizontal layers cannot account for the deduced density relationships nor for the withdrawal pattern
Erythropoietic protoporphyria without skin symptoms-you do not always see what they feel
Erythropoietic protoporphyria (EPP) is an inherited disorder of the porphyrin metabolism that often remains undiagnosed in children. We report on a 4-year-old girl who had been suffering for 1 year from recurrent painful crises affecting her hands, feet, and nose following sun exposure. Objective skin lesions were absent until the age of 6. Porphyrin analysis revealed elevated free erythrocyte protoporphyrin (FEP) levels confirming the diagnosis of EPP. This illustrates that skin lesions might be completely absent in children affected with EPP, a fact that has only been reported once previously. Because EPP can manifest with few and unspecific cutaneous symptoms or no skin lesions at all, like in this patient, the diagnosis of EPP might be delayed or missed. EPP should be excluded in all photosensitive children, especially when discomfort is disproportionate to the extent of the cutaneous lesions. The clinic, pathophysiology, diagnosis, complications, and therapy of EPP are discussed
Controversies concerning the diagnosis and treatment of bipolar disorder in children
This commentary grows out of an interdisciplinary workshop focused on controversies surrounding the diagnosis and treatment of bipolar disorder (BP) in children. Although debate about the occurrence and frequency of BP in children is more than 50 years old, it increased in the mid 1990s when researchers adapted the DSM account of bipolar symptoms to diagnose children. We offer a brief history of the debate from the mid 90s through the present, ending with current efforts to distinguish between a small number of children whose behaviors closely fit DSM criteria for BP, and a significantly larger number of children who have been receiving a BP diagnosis but whose behaviors do not closely fit those criteria. We agree with one emerging approach, which gives part or all of that larger number of children a new diagnosis called Severe Mood Dysregulation or Temper Dysregulation Disorder with Dysphoria
Unrecognized Non-Q-Wave Myocardial Infarction: Prevalence and Prognostic Significance in Patients with Suspected Coronary Disease
Using delayed-enhancement cardiovascular magnetic resonance, Han Kim and colleagues show that in patients with suspected coronary disease the prevalence of unrecognized myocardial infarction without Q-waves is more than 3-fold higher than that with Q-waves and predicts subsequent mortality
Hippocampal - diencephalic - cingulate networks for memory and emotion: An anatomical guide
This review brings together current knowledge from tract tracing studies to update and reconsider those limbic connections initially highlighted by Papez for their presumed role in emotion. These connections link hippocampal and parahippocampal regions with the mammillary bodies, the anterior thalamic nuclei, and the cingulate gyrus, all structures now strongly implicated in memory functions. An additional goal of this review is to describe the routes taken by the various connections within this network. The original descriptions of these limbic connections saw their interconnecting pathways forming a serial circuit that began and finished in the hippocampal formation. It is now clear that with the exception of the mammillary bodies, these various sites are multiply interconnected with each other, including many reciprocal connections. In addition, these same connections are topographically organised, creating further subsystems. This complex pattern of connectivity helps explain the difficulty of interpreting the functional outcome of damage to any individual site within the network. For these same reasons, Papezâs initial concept of a loop beginning and ending in the hippocampal formation needs to be seen as a much more complex system of hippocampalâdiencephalicâcingulate connections. The functions of these multiple interactions might be better viewed as principally providing efferent information from the posterior medial temporal lobe. Both a subcortical diencephalic route (via the fornix) and a cortical cingulate route (via retrosplenial cortex) can be distinguished. These routes provide indirect pathways for hippocampal interactions with prefrontal cortex, with the preponderance of both sets of connections arising from the more posterior hippocampal regions. These multi-stage connections complement the direct hippocampal projections to prefrontal cortex, which principally arise from the anterior hippocampus, thereby creating longitudinal functional differences along the anteriorâposterior plane of the hippocampus
Training in crisis communication and volcanic eruption forecasting:Design and evaluation of an authentic role-play simulation
We present an interactive, immersive, authentic role-play simulation designed to teach tertiary geoscience students
in New Zealand to forecast and mitigate a volcanic crisis. Half of the participating group (i.e., the Geoscience Team)
focuses on interpreting real volcano monitoring data (e.g., seismographs, gas output etc.) while the other half of the
group (i.e., the Emergency Management Team) forecasts and manages likely impacts, and communicates emergency
response decisions and advice to local communities. These authentic learning experiences were aimed at enhancing
upper-year undergraduate studentsâ transferable and geologic reasoning skills. An important goal of the simulation was
specifically to improve studentsâ science communication through interdisciplinary team discussions, jointly prepared,
and delivered media releases, and real-time, high-pressure, press conferences.
By playing roles, students experienced the specific responsibilities of a professional within authentic organisational
structures. A qualitative, design-based educational research study was carried out to assess the overall student experience
and self-reported learning of skills. A pilot and four subsequent iterations were investigated.
Results from this study indicate that students found these role-plays to be a highly challenging and engaging learning
experience and reported improved skills. Data from classroom observations and interviews indicate that the students
valued the authenticity and challenging nature of the role-play although personal experiences and team dynamics
(within, and between the teams) varied depending on the studentsâ background, preparedness, and personality.
During early iterations, observation and interviews from students and instructors indicate that some of the goals of the
simulation were not fully achieved due to: A) lack of preparedness, B) insufficient time to respond appropriately, C)
appropriateness of roles and team structure, and D) poor communication skills. Small modifications to the design of
Iterations 3 and 4 showed an overall improvement in the studentsâ skills and goals being reached.
A communication skills instrument (SPCC) was used to measure self-reported pre- and post- communication competence
in the last two iterations. Results showed that this instrument recorded positive shifts in all categories of self-perceived
abilities, the largest shifts seen in students who participated in press conferences. Future research will be aimed
at adapting this curricula to new volcanic and earthquake scenarios
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