Time Travel Research Articles

Endel Tulving (1927-2023).

This article presents an obituary for Endel Tulving. Tulving's educational and professional careers are summarized. His work in the field of human memory is detailed. It is noted that Tulving's look at the field of verbal learning in the late 1950s persuaded him that the dominant associative tradition missed many important aspects of human memory. His research found that at the time of retrieval, memory for the original event may be successfully reinstated only by contextual cues that interact in a complementary fashion with the specifically encoded memory trace, a process that Tulving referred to as "synergistic ecphory". He is also known for his work on memory systems. In his book, Elements of Episodic Memory published in 1983, Tulving proposed that memory for experienced events, episodic memory, should be distinguished from general knowledge of the world, semantic memory, and from procedural memory, the learned ability to perform such skilled procedures as riding a bicycle or playing a musical instrument. He also proposed an evolutionary framework for these different but related systems, suggesting that simple animals show only procedural memory, more complex animals are consciously aware of their knowledge of the world, but only humans possess episodic memory-the ability to use "mental time travel" to consciously recreate past experiences and to imagine possible future events. Although known initially for his purely cognitive behavioral research, during the 1980s and 1990s, Tulving increasingly incorporated neuropsychological and neuroimaging approaches into his work. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Measuring Qubits with “Time Travel” Protocol

Measuring Qubits with “Time Travel” Protocol

Anatomical Features and Material Properties of Human Surrogate Head Models Affect Spatial and Temporal Brain Motion under Blunt Impact.

Traumatic brain injury (TBI) is a biomechanical problem where the initiating event is dynamic loading (blunt, inertial, blast) to the head. To understand the relationship between the mechanical parameters of the injury and the deformation patterns in the brain, we have previously developed a surrogate head (SH) model capable of measuring spatial and temporal deformation in a surrogate brain under blunt impact. The objective of this work was to examine how material properties and anatomical features affect the motion of the brain and the development of injurious deformations. The SH head model was modified to study six variables independently under blunt impact: surrogate brain stiffness, surrogate skull stiffness, inclusion of cerebrospinal fluid (CSF), head/skull size, inclusion of vasculature, and neck stiffness. Each experimental SH was either crown or frontally impacted at 1.3 m/s (3 mph) using a drop tower system. Surrogate brain material, the Hybrid III neck stiffness, and skull stiffness were measured and compared to published properties. Results show that the most significant variables affecting changes in brain deformation are skull stiffness, inclusion of CSF and surrogate brain stiffness. Interestingly, neck stiffness and SH size significantly affected the strain rate only suggesting these parameters are less important in blunt trauma. While the inclusion of vasculature locally created strain concentrations at the interface of the artery and brain, overall deformation was reduced.

Real-World Spatial Synchronization of Event-CMOS Cameras through Deep Learning: A Novel CNN-DGCNN Approach.

This paper presents a new deep-learning architecture designed to enhance the spatial synchronization between CMOS and event cameras by harnessing their complementary characteristics. While CMOS cameras produce high-quality imagery, they struggle in rapidly changing environments-a limitation that event cameras overcome due to their superior temporal resolution and motion clarity. However, effective integration of these two technologies relies on achieving precise spatial alignment, a challenge unaddressed by current algorithms. Our architecture leverages a dynamic graph convolutional neural network (DGCNN) to process event data directly, improving synchronization accuracy. We found that synchronization precision strongly correlates with the spatial concentration and density of events, with denser distributions yielding better alignment results. Our empirical results demonstrate that areas with denser event clusters enhance calibration accuracy, with calibration errors increasing in more uniformly distributed event scenarios. This research pioneers scene-based synchronization between CMOS and event cameras, paving the way for advancements in mixed-modality visual systems. The implications are significant for applications requiring detailed visual and temporal information, setting new directions for the future of visual perception technologies.

Time-mapping and future-oriented behavior in free-ranging wild fruit bats

Episodic memory and mental time travel have been viewed as uniquely human traits.1,2,3 This view began to shift with the development of behavioral criteria to assess what is referred to as "episodic-like memory" in animals.4,5 Key findings have ranged from evidence of what-where-when memory in scrub-jays, rats, and bees; through decision-making that impacts future foraging in frugivorous primates; to evidence of planning based on future needs in scrub-jays and tool use planning in great apes.4,6,7,8,9,10,11,12,13 Field studies of these issues have been rare, though there is field-based evidence for future-oriented behaviors in primates.8,10,14,15 We report evidence that free-ranging wild fruit bats rely on mental temporal maps and exhibit future-oriented behaviors when foraging. We tracked young bats as they navigated and foraged, documenting every tree they visited over many months. We prevented the bats from foraging outside for different time periods and monitored their foraging decisions, revealing that the bats map the spatiotemporal patterns of resources in their environment. Following a long period in captivity, the bats did not visit those trees that were no longer providing fruit. We show that this time-mapping ability requires experience and is lacking in inexperienced bats. Careful analysis of the bats' movement and foraging choices indicated that they plan which tree to visit while still in the colony, thus exhibiting future-oriented behavior and delayed gratification on a nightly basis. Our findings demonstrate how the need for spatiotemporal mental mapping can drive the evolution of high cognitive abilities that were previously considered exclusive to humans.

Temporal displacement: colonial architecture and its contestation

Between 1950 and 1979 the Danish state worked to modernise Kalaallit Nunaat (a.k.a. Greenland) and concentrate the Indigenous Inuit population in a few select cities. Technologies of urban planning and development were merged with those of the colonial state. New forms of housing materialised whose qualities aligned with assimilation schemes, but were also resisted, their uses repurposed. These movements and counter-movements, I show, speak to how the built environment scripts time and temporality. Considering architecture as a ‘material politics of time’, I develop the concept of ‘temporal displacement’ in close conversation with the empirical material examined: archival materials and documents key to shaping and effectuating Danish-led policies, and documents that speak to Kalaallit’s contestation of the new types of housing being introduced. Three main aspects to temporal displacement are emphasised: (I) the eviction of the present to the past and the anachronism that follows from this; (II) biopolitical materialisations of the so-called ‘new order’; and (III) contestation by claiming contemporaneity for temporally evicted practices, activating that which hegemonic time renders as past as being in the present. The concept of ‘active past’ is suggested to capture how ideas of the past are activated in, unsettled, and renegotiated in the present.

Reliability and Unreliability Aspects of Travel Time Analysis on the Stochastic Network Using the Target-Oriented Perspective

This study proposes a target-oriented method to study travelers’ route choice behavior under travel time variability, and discusses the resulted equilibrium flow patterns. Both travel time reliability and travel time unreliability are considered in this new method, and accordingly, there are two targets. The first one is target for travel time to ensure travel time reliability, and based on this target, another one is target for excess delay to mitigate travel time unreliability. In this model, travel time and excess delay (i.e., the random vector) are stochastically correlated with each other, which is modeled with the copula function based on Sklar’s Theorem, and the exact form of the copula is obtained by the proved comonotonicity relationship of this random vector. The target interaction, i.e., the complementarity relationship, is also modeled based on the utility functions, the meaning of which is that travelers have the will to make more targets achieved so as to obtain more utility. Furthermore, with this model, this paper formulates the user equilibrium as a variational inequality problem to study the long-term effect of the route choice behavior, and solves it with the method of successive average. Finally, numerical testings on the traffic network are conducted to show the convergence of the solution algorithm, and to illustrate the impact of targets on the equilibrium results. Results show that the flow change can be five times more than that with less risk-averse travelers.

Analysis of losses in physiotherapy students during the COVID-19 pandemic: a phenomenological approach

BackgroundDuring the COVID-19 pandemic, young people have experienced numerous personal losses across various aspects, impacting their quality of life. This study aimed to explore and analyze the losses experienced by physiotherapy students during the first year of the COVID-19 pandemic.MethodsA qualitative phenomenological study was conducted using an open-format exercise carried out during the Clinical Specialties class from February to May 2021. Thirty-four (83% female) third-year physical therapy students participated. ATLAS.ti software was used for the analysis and coding by three researchers.ResultsAnalysis of the categories revealed various losses experienced by the participants, including losses in psychological well-being, physical health, the social sphere (friendships, relationships with partners and family members, and experiences of death), spiritual losses (loss of freedom and identity), leisure time (travel, recreational activities and physical exercise), and different losses related to university studies (motivation and enthusiasm and clinical practices).ConclusionThe COVID-19 pandemic has led to significant losses among physiotherapy students, with losses in the social sphere being the most prevalent. This study can serve as a foundation for developing resources aimed at enhancing the well-being of physiotherapy students, promoting optimal academic performance, improving self-care, and reducing psychosocial problems.

Factors affecting evacuation in intellectually disabled children: An experimental study

Children with intellectual disabilities are considered a vulnerable group in evacuations during emergencies, yet their evacuation needs have not received sufficient attention. To bridge this gap, this study provides one of the very few experimental analyses of the evacuation of intellectually disabled children. Therefore, this study aimed to gather unique evacuation data for intellectually disabled children and identify factors influencing their evacuation process. Two evacuation experiments were conducted on 49 intellectually disabled children aged 7 to 16 from a special education school. Data collected through video recordings include recognition time, response time, pre-movement time, indoor travel speed, horizontal travel speed, and vertical travel speed. This study explored whether and how several key factors (e.g., drill announcement status, sex, age, floor level, and students' dependency behavior) affect the evacuation of intellectually disabled children. Results indicate that drill announcement status significantly affected the recognition time and pre-movement time in intellectually disabled children but did not impact their response time or travel speed. The floor level on which children were located significantly influenced their evacuation process, with children on higher floors showing longer response and pre-movement time and slower indoor travel speed and horizontal travel speed compared to those on the first floor. Additionally, the dependency behavior of these children on teachers significantly influenced their recognition time. Moreover, this dependency behavior tended to be prevalent among intellectually disabled children during emergency evacuations. These findings provide valuable insights for the design of educational buildings tailored to the needs of special populations, evacuation simulation modeling, and the development of building regulations.

EDUCATION'S ROLE IN PRIMARY HEALTHCARE UTILIZATION AMONG OLDER PEOPLE IN INDONESIA

Introduction: The current situation shows that life expectancy is increasing, so the population of older people is also growing. As a vulnerable group, more senior people desperately need primary health care, and barriers to accessing services will increase vulnerability. Aim: The study aimed to investigate the impact of education on primary healthcare utilization among older people. Methods: This cross-sectional study examined 52,893 older people. It employed primary healthcare utilization as an outcome variable and education level as an exposure variable. Furthermore, the study used eight control variables: residence type, age group, gender, marital status, wealth, time travel to primary healthcare, and health insurance. We employed binary logistic regression to examine the data. Results: The study showed that older adults with primary education were 1.050 times more likely than those without to utilize primary healthcare (95% CI 1.046-1.054). Older people with secondary education were 0.643 times less likely to use primary healthcare than those without (95% CI 0.638-0.649). Older adults with secondary education were 0.378 times less likely than those without to use primary healthcare (95% CI 0.372-0.383). Furthermore, the study indicated that all control variables were significantly related to direct healthcare utilization. Conclusion: The study concluded that education level influences primary healthcare utilization among older people in Indonesia. Keywords: elderly people, education, primary healthcare, healthcare evaluation, healthcare access, public health

Personal identity and mental time travel

This paper examines the role of episodic memory, and the broader notion of “mental time travel” (MTT), in constituting personal identity. After arguing that the construal of memory’s role in personal identity found in traditional psychological continuity theories of personal identity is both unrealistic and unsatisfying, the paper endeavors to provide a better account. This begins with recent work in the science and philosophy of memory that sees episodic memory as part of a broader faculty for MTT (which also involves imagination and counterfactual thought). Some of the basic ideas expressed in this work are developed into an account of the connection between MTT with “strong identification” and personal identity. According to this alternative approach, we regularly “borrow affect” from our pasts and futures through forms of remembering, imagining, and counterfactual thinking that involve a particular form of identification with our past and future selves. This activity generates a strong diachronic experience of self, which contributes in important ways to diachronic personal identity. The sense of self generated through MTT is, however, only one piece of a more comprehensive account of personal identity. The paper concludes by describing its place in the larger picture.

Social-STGMLP: A Social Spatio-Temporal Graph Multi-Layer Perceptron for Pedestrian Trajectory Prediction

As autonomous driving technology advances, the imperative of ensuring pedestrian traffic safety becomes increasingly prominent within the design framework of autonomous driving systems. Pedestrian trajectory prediction stands out as a pivotal technology aiming to address this challenge by striving to precisely forecast pedestrians’ future trajectories, thereby enabling autonomous driving systems to execute timely and accurate decisions. However, the prevailing state-of-the-art models often rely on intricate structures and a substantial number of parameters, posing challenges in meeting the imperative demand for lightweight models within autonomous driving systems. To address these challenges, we introduce Social Spatio-Temporal Graph Multi-Layer Perceptron (Social-STGMLP), a novel approach that utilizes solely fully connected layers and layer normalization. Social-STGMLP operates by abstracting pedestrian trajectories into a spatio-temporal graph, facilitating the modeling of both the spatial social interaction among pedestrians and the temporal motion tendency inherent to pedestrians themselves. Our evaluation of Social-STGMLP reveals its superiority over the reference method, as evidenced by experimental results indicating reductions of 5% in average displacement error (ADE) and 17% in final displacement error (FDE).

The hippocampus dissociates present from past and future goals

Our brain adeptly navigates goals across time frames, distinguishing between urgent needs and those of the past or future. The hippocampus is a region known for supporting mental time travel and organizing information along its longitudinal axis, transitioning from detailed posterior representations to generalized anterior ones. This study investigates the role of the hippocampus in distinguishing goals over time: whether the hippocampus encodes time regardless of detail or abstraction, and whether the hippocampus preferentially activates its anterior region for temporally distant goals (past and future) and its posterior region for immediate goals. We use a space-themed experiment with 7T functional MRI on 31 participants to examine how the hippocampus encodes the temporal distance of goals. During a simulated Mars mission, we find that the hippocampus tracks goals solely by temporal proximity. We show that past and future goals activate the left anterior hippocampus, while current goals engage the left posterior hippocampus. This suggests that the hippocampus maps goals using timestamps, extending its long axis system to include temporal goal organization.

On causality violation in different classes of Ricci inverse gravity

In this paper, we investigate a causality-violating four-dimensional space-time, an extension of the two-dimensional Misner space within the framework of modified gravity theories, specifically in the context of Ricci-inverse gravity. To explore this, we focus on two classes of models denoted as f(R,AμνAμν)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f({\\mathcal {R}}, A^{\\mu \ u }\\,A_{\\mu \ u })$$\\end{document} and f(R,A,AμνAμν)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f({\\mathcal {R}}, {\\mathcal {A}}, A^{\\mu \ u }\\,A_{\\mu \ u })$$\\end{document}, and derive the modified field equations using the four-dimensional space-time under consideration. Here, Aμν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$A^{\\mu \ u }$$\\end{document} is the anti-curvature tensor defined by inverse of the Ricci tensor Rμν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R_{\\mu \ u }$$\\end{document}, that is, Aμν=Rμν-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$A^{\\mu \ u }=R^{-1}_{\\mu \ u }$$\\end{document}. Additionally, A\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {A}}$$\\end{document} denotes its scalar, defined as A=gμνAμν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {A}}=g_{\\mu \ u }\\,A^{\\mu \ u }$$\\end{document}. Our analysis shows that in both models, the modified field equations can be solved by considering the matter energy content as a pure radiation field including the cosmological constant. Furthermore, we demonstrate that the energy density of the pure radiation field and the cosmological constant undergo modifications due to the coupling parameters, and these modifications converge to the results of general relativity when these parameters are set to zero. This observation confirms the possibility of causality violation in the form of closed time-like curves within the framework of Ricci-inverse gravity theory.

Vision-Based Reactive Temporal Logic Motion Planning for Quadruped Robots in Unstructured Dynamic Environments

Vision-Based Reactive Temporal Logic Motion Planning for Quadruped Robots in Unstructured Dynamic Environments

Potential Sunda Strait tsunami hazard due to the current deformation of Anak Krakatau

Abstract The tsunami Sunda Strait event at 2018 is a prove that volcanic activity may trigger a devastating and unpredictable tsunami. Several findings indicate that this catasrophe generated by flank collapse caused by the instability of Gunung Anak Krakatau (AK). Other processes of volcanic activity that cause tsunamis include pyroclastic flows, subaerial and submarine landslides, underwater explosions, blasts, and caldera collapse. In the 1883, Krakatau Mount produced the largest tsunami event, and it is apparent that AK is one of threats in Sunda Strait that may potentially produce tsunami in the future since it is still active until now. Some latest research shows there are two submarine landslide threats near Gunung Anak Krakatau; in the northeast part of AK and an elliptical landslide source in the west part of AK with the estimated landslide volume about 0.014 km3 and 0.6 km3, respectively. Those threats will be simulated by shallow water equation model to obtain the tsunami wave height near the source and at crucial areas along Sunda Strait as well as its tsunami time arrival. The first scenario is sourced from a new deposit from the 2018 eruption, and the latter is a change of slopes bathymetry due to volcanic or seismic activity. It is observed that the highest elevation of tsunami from the first scenario reached only 2.5 cm at Tanjung Lesung, Banten and 80 cm at the nearest island, Panjang Island. The second scenario has the height of 50 cm at Labuan, Banten and 70 cm at Panjang Island. The tsunami time travel at the surrounding islands is ranging between 0.6 - 5.8 minutes (scenario 1) and 0.7-4.9 minutes (scenario 2). Both scenario reached the inexpensive device of sea level monitoring at the east side of Rakata after 5 minutes and the height is 30 cm and 1.6 cm respectively for scenario 1 and 2.

Improved Transcranial Plane-Wave Imaging With Learned Speed-of-Sound Maps.

Although transcranial ultrasound plane-wave imaging (PWI) has promising clinical application prospects, studies have shown that variable speed-of-sound (SoS) would seriously damage the quality of ultrasound images. The mismatch between the conventional constant velocity assumption and the actual SoS distribution leads to the general blurring of ultrasound images. The optimization scheme for reconstructing transcranial ultrasound image is often solved using iterative methods like full-waveform inversion. These iterative methods are computationally expensive and based on prior magnetic resonance imaging (MRI) or computed tomography (CT) information. In contrast, the multi-stencils fast marching (MSFM) method can produce accurate time travel maps for the skull with heterogeneous acoustic speed. In this study, we first propose a convolutional neural network (CNN) to predict SoS maps of the skull from PWI channel data. Then, use these maps to correct the travel time to reduce transcranial aberration. To validate the performance of the proposed method, numerical, phantom and intact human skull studies were conducted using a linear array transducer (L11-5v, 128 elements, pitch = 0.3 mm). Numerical simulations demonstrate that for point targets, the lateral resolution of MSFM-restored images increased by 65%, and the center position shift decreased by 89%. For the cyst targets, the eccentricity of the fitting ellipse decreased by 75%, and the center position shift decreased by 58%. In the phantom study, the lateral resolution of MSFM-restored images was increased by 49%, and the position shift was reduced by 1.72 mm. This pipeline, termed AutoSoS, thus shows the potential to correct distortions in real-time transcranial ultrasound imaging, as demonstrated by experiments on the intact human skull.

Racial Biases in AIs and Gemini's Inability to Write Narratives About Black People

This article addresses the racism that emerges in artificial intelligence based on an experiment carried out in Gemini, Google's text-generative tool that uses natural language. In an attempt to observe possible racial biases in the chatbot's responses, commands reproduced for the binary matrices man/woman and white/black were submitted in order to compare the responses, but Gemini, despite having text production as its primary function, was unable to generate narratives that involved black people. This empirical experimentation was analyzed according to a bibliographical review of authors who deal with racial themes, mainly considering the view of Denise Ferreira da Silva in relation to the idea of a transparent subjectivity, the temporal displacement of the black body discussed by Bhabha and the overlap between technology and race brought by Noble and Faustino and Lippold. This erasure of minoritized racial groups is not restricted to the tool or the algorithmic means, but is a symptom of other exclusionary practices observed in society.

Laparoscopic distal gastrectomy skill evaluation from video: a new artificial intelligence-based instrument identification system

The advent of Artificial Intelligence (AI)-based object detection technology has made identification of position coordinates of surgical instruments from videos possible. This study aimed to find kinematic differences by surgical skill level. An AI algorithm was developed to identify X and Y coordinates of surgical instrument tips accurately from video. Kinematic analysis including fluctuation analysis was performed on 18 laparoscopic distal gastrectomy videos from three expert and three novice surgeons (3 videos/surgeon, 11.6 h, 1,254,010 frames). Analysis showed the expert surgeon cohort moved more efficiently and regularly, with significantly less operation time and total travel distance. Instrument tip movement did not differ in velocity, acceleration, or jerk between skill levels. The evaluation index of fluctuation β was significantly higher in experts. ROC curve cutoff value at 1.4 determined sensitivity and specificity of 77.8% for experts and novices. Despite the small sample, this study suggests AI-based object detection with fluctuation analysis is promising because skill evaluation can be calculated in real time with potential for peri-operational evaluation.

Influence of a Pair of Unequal Rotational Fluxes on Entrained Gaseous Filament

Abstract Efforts are made to elucidate a comprehensive analysis of entrainment dynamics triggered by a couple of unequal rotational fluxes within a viscous pool. Cylindrical rollers are employed to establish the rotational field. The top drum is equally submerged in both phases and also it provides a constant rotational inertia. Concomitantly, the bottom roller is completely submerged in the viscous bath, and it provides an unequal rotational strength in reference to top roller. The average rotational strength of both rollers is measured using average Capillary number (Caavg). The entrainment phenomenon is strongly influenced by both Caavg and gap between the rollers (W/D). Characterization of entrained filament is elucidated by predicting the horizontal distance (L*), radial distance (r*), temporal vertical displacement (Y*), maximum vertical displacement (Ymax*), width (H*), and location of V-shaped diversion (Øs*). Characterization of liquid tip is performed by measuring the travel rate (γ*) along periphery of drum from receding to advancing junction. Air mass ejection from filament tip is analyzed by estimating the first bubble ejection time (t1st*), volume of accumulated of ejected gaseous masses (v*), and ejection frequency (f). Furthermore, the effect of gravitational pull (specified by Archimedes number, Ar) and viscous drag (measured by Morton number, Mo) on the pattern of entrained air filament is described. Lastly, an analytical framework is established to determine the width of the V-junction by balancing the important influencing forces, which are strongly affecting the filament. Analytical observations show a satisfactory agreement with numerical findings.