Robot Navigation in Unseen Spaces using an Abstract Map

Human navigation in built environments depends on symbolic spatial information which has unrealised potential to enhance robot navigation capabilities. Information sources such as labels, signs, maps, planners, spoken directions, and navigational gestures communicate a wealth of spatial information to the navigators of built environments; a wealth of information that robots typically ignore. We present a robot navigation system that uses the same symbolic spatial information employed by humans to purposefully navigate in unseen built environments with a level of performance comparable to humans. The navigation system uses a novel data structure called the abstract map to imagine malleable spatial models for unseen spaces from spatial symbols. Sensorimotor perceptions from a robot are then employed to provide purposeful navigation to symbolic goal locations in the unseen environment. We show how a dynamic system can be used to create malleable spatial models for the abstract map, and provide an open source implementation to encourage future work in the area of symbolic navigation. Symbolic navigation performance of humans and a robot is evaluated in a real-world built environment. The paper concludes with a qualitative analysis of human navigation strategies, providing further insights into how the symbolic navigation capabilities of robots in unseen built environments can be improved in the future.Comment: 15 pages, published in IEEE Transactions on Cognitive and Developmental Systems (http://doi.org/10.1109/TCDS.2020.2993855), see https://btalb.github.io/abstract_map/ for access to softwar

Condensate density and superfluid mass density of a dilute Bose gas near the condensation transition

We derive, through analysis of the structure of diagrammatic perturbation theory, the scaling behavior of the condensate and superfluid mass density of a dilute Bose gas just below the condensation transition. Sufficiently below the critical temperature, $T_c$, the system is governed by the mean field (Bogoliubov) description of the particle excitations. Close to $T_c$, however, mean field breaks down and the system undergoes a second order phase transition, rather than the first order transition predicted in Bogoliubov theory. Both condensation and superfluidity occur at the same critical temperature, $T_c$ and have similar scaling functions below $T_c$, but different finite size scaling at $T_c$ to leading order in the system size. Through a simple self-consistent two loop calculation we derive the critical exponent for the condensate fraction, $2\beta\simeq 0.66$.Comment: 4 page

Place Categorization and Semantic Mapping on a Mobile Robot

In this paper we focus on the challenging problem of place categorization and semantic mapping on a robot without environment-specific training. Motivated by their ongoing success in various visual recognition tasks, we build our system upon a state-of-the-art convolutional network. We overcome its closed-set limitations by complementing the network with a series of one-vs-all classifiers that can learn to recognize new semantic classes online. Prior domain knowledge is incorporated by embedding the classification system into a Bayesian filter framework that also ensures temporal coherence. We evaluate the classification accuracy of the system on a robot that maps a variety of places on our campus in real-time. We show how semantic information can boost robotic object detection performance and how the semantic map can be used to modulate the robot's behaviour during navigation tasks. The system is made available to the community as a ROS module

My Body, My Post: Emerging Adult Women and Presentation of Body and Sexuality on Social Networking Sites

Thesis advisor: Usha Tummala-NarraWomen receive many contradictory messages about what their bodies should look like and how they should behave. These messages necessarily impact how women are socialized to use social media and how they engage with online platforms. Little attention has been paid to the impact of these mixed messages on women’s self-concept and social engagement online, or to the mental health and social consequences of these interactions. The present study, guided by Objectification Theory (Fredrickson & Roberts, 1997) and Relational Cultural Theory (Miller, 1976), intended to gain a deeper understanding of how emerging adult women understand the messages they receive about their bodies and what they should be used for and how these messages influence their relational behaviors online. Semi-structured interviews were conducted with 14 women (ages 19-25), focusing on messages concerning expectations of women’s bodies and sexuality, performance of body and sexuality in social media spaces, social media activism, and social interactions online. Conventional content analysis was used to examine the interviews. Interview data revealed multiple themes, composing four broad domains: (1) expectations of women; (2) social media curation; (3) mental health and social effects of social media use; and (4) activism and advocacy. Notions about how women wanted to perform their identities online were shaped by several factors, including aspirational goals for self-love and body acceptance, an interest in portraying themselves authentically and in the best possible light, and a desire to be part of a movement of social change. The study underscores the impact of social media in individual functioning and wellbeing and reveals deep-seated conflict that women face in integrating messages about who they should be with performance of their own identities. This study highlights the need for situationally responsive clinical practice, intervention, and future research.Thesis (PhD) — Boston College, 2022.Submitted to: Boston College. Lynch School of Education.Discipline: Counseling, Developmental and Educational Psychology

The symmetric quasi-classical model using on-the-fly time-dependent density functional theory within the Tamm-Dancoff approximation

The primary computational challenge when simulating nonadiabatic ab initio molecular dynamics is the unfavorable compute costs of electronic structure calculations with molecular size. Simple electronic structure theories, like time-dependent density functional theory within the Tamm-Dancoff approximation (TDDFT/TDA), alleviate this cost for moderately sized molecular systems simulated on realistic time scales. Although TDDFT/TDA does have some limitations in accuracy, an appealing feature is that, in addition to including electron correlation through the use of a density functional, the cost of calculating analytic nuclear gradients and nonadiabatic coupling vectors is often computationally feasible even for moderately-sized basis sets. In this work, some of the benefits and limitations of TDDFT/TDA are discussed and analyzed with regard to its applicability as a "back-end" electronic structure method for the symmetric quasi-classical Meyer-Miller model (SQC/MM). In order to investigate the benefits and limitations of TDDFT/TDA, SQC/MM is employed to predict and analyze a prototypical example of excited-state hydrogen transfer in gas-phase malonaldehyde. Then, the ring-opening dynamics of selenophene are simulated which highlight some of the deficiencies of TDDFT/TDA. Additionally, some new algorithms are proposed that speed up the calculation of analytic nuclear gradients and nonadiabatic coupling vectors for a set of excited electronic states.Comment: 35 pages, 8 figures, 2 table

‘Just another hurricane’: the lived experience of everyday life in Plaquemines Parish, Louisiana in the aftermath of Hurricane Katrina and the BP oil spill

This thesis offers an ethnographic analysis of everyday life in a post-catastrophe landscape shaped by two major disaster-processes – Hurricane Katrina (in 2005) and the BP oil spill (in 2010). By exploring local cultural ‘becoming’, it argues that the impact of these disaster-processes should not be conceptualised within a bounded period of ‘recovery’, but should be understood as forming part of the on-going construction of local landscape and everyday lived experience. The community of southern Plaquemines Parish, Louisiana, where this study was based, has an on-going relationship with hurricanes and oil spills, which occur (or threaten to occur) with such frequency as to normalise the experience of disaster in local social life. Katrina and the BP oil spill were outliers of experience due to their vast scale and relative impact, but they were experienced by a community where local narratives of past catastrophes (such as the major hurricanes of the 1960s), and the direct experience of multiple smaller disaster-processes were deeply woven into local culture. Furthermore, beyond the impact of these catastrophes this community was already experiencing widespread cultural and economic precariousness. Firstly, where local hierarchies of power (largely centred around White men) had become increasingly threatened in the latter part of the 20th century, and secondly, where local economic activity was characterised by high levels of instability and irregular employment. These catastrophes were therefore experienced in a context of already on-going structural precariousness, which in turn was impacted by the on-going ‘recovery’ from these large disaster-processes. It argues that while material or institutional reconstruction may be successfully measured in terms of recovery goals or milestones, the cultural impact and ‘recovery’ from these catastrophes should be conceptualised as forming part of the never-ending process of ‘becoming’, ultimately woven into the on-going experience of mundane everyday life

Switching anti-CGRP monoclonal antibodies in chronic migraine:real-world observations of erenumab, fremanezumab and galcanezumab

Objectives: The anti-calcitonin gene-related peptide monoclonal antibodies (anti-CGRP-mAb) are effective in migraine; however, few studies have examined the benefit of switching from one anti-CGRP-mAb to another. In order to better inform clinical practice in this situation, we present our real-world findings of switching anti-CGRP-mAb in chronic migraine. Methods: Individuals with chronic migraine that switched anti-CGRP-mAb treatment (erenumab, fremanezumab or galcanezumab) due to ineffectiveness or adverse effects were retrospectively identified. Headache diary data before and up to 6 months after anti-CGRP-mAb switch were analysed. Main outcome measures were monthly red days (days with headaches limiting activity or requiring triptans), headache days (days with any kind of headache), triptan use, other analgesic use and headache disability (Headache Impact Test-6 (HIT-6) score) at 3 months. Results: The analysis included 66 instances of switching among 54 individuals. There were non-significant reductions of −1.2 (−2.7, 0.3) red days from baseline at 3 months, with 10 individuals (15%) showing ≥50% improvement and 22 (33%) experiencing a ≥30% improvement. Improvements in headache days, triptan days, other painkiller use and HIT-6 score were non-significant. When individuals that switched due to side effects were excluded from the analysis, significant reductions in headache (Friedman p=0.044) and a trend for improvement in red days (Friedman p=0.083) were observed. With regard to side effects, on 12 occasions these improved or resolved on switching to a different anti-CGRP-mAb, while new symptoms were reported on eight occasions following a switch. Conclusion: We recorded modest improvements in headache outcomes, although significant results were only observed in those that switched anti-CGRP-mAb due to ineffectiveness. Switching may therefore be a viable option for these individuals

Fantastical Excited State Optimized Structures and Where to Find Them

The quantum chemistry community has developed analytic forces for approximate electronic excited states to enable walking on excited state potential energy surfaces (PES). One can thereby computationally characterize excited state minima and saddle points. Always implicit in using this machinery is the fact that an excited state PES only exists within the realm of the Born-Oppenheimer approximation, where the nuclear and electronic degrees of freedom separate. This work demonstrates through ab initio calculations and simple nonadiabatic dynamics that some excited state minimum structures are fantastical: they appear to exist as stable configurations only as a consequence of the PES construct, rather than being physically observable. One such case is the S2 excited state of phosphine and a second case are local minima of a number of states of tris(bipyridine)ruthenium(II). Each fantastical structure exhibits an unphysically high predicted harmonic frequency and associated force constant. This fact can serve as a valuable diagnostic of when an optimized excited state structure is non-observable. Their origin lies in the coupling between different electronic states, and the resulting avoided crossings. The upper state may exhibit a minimum very close to the crossing, where the force constant relates to the strength of the electronic coupling rather than to any characteristic excited state vibration. Nonadiabatic dynamics results using a Landau-Zener model illustrate that fantastical excited state structures have extremely short lifetimes on the order of a few femtoseconds. Their appearance in a calculation signals the presence of a nearby avoided crossing or conical intersection through which the system will rapidly cross to a lower surface.Comment: 7 pages, 4 figure

How medical students demonstrate their professionalism when reflecting on experience

Objectives:  This paper aims to examine the discourses used by students in a formal assessment of their ability to demonstrate professional values when reflecting on their experiences. Methods:  We carried out a discourse analysis of 50 randomly selected essays from a summative assessment undertaken by all five year groups of students in one UK medical school. Results:  Students were able to identify a wealth of relevant examples and to articulate key principles of professional practice. They were also able to critique behaviours and draw appropriate conclusions for their own intended professional development. Detailed textual analysis provided linguistic clues to the depth of apparent reflection: recurrent use of rhetorical language with minimal use of first-person reflections, lack of analysis of underlying factors, and simplistic views of solutions may all indicate students whose ability to learn by reflection on experience needs further development. There were also areas in which cohorts as a whole appeared to have a limited grasp of the important professional issues being addressed. Conclusions:  Assessing written reflections is a useful way of making students link their experiences with professional development. The detailed analysis of language usage may help to refine marking criteria, and to detect students and course components where reflective learning competencies are not being achieved