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1. 6Fit-A-Part: A Protocol for Physical Distancing on a Custom Wearable Device

   https://doi.org/10.1109/ICNP49622.2020.9259374  

   Cao, Yifeng; Dhekne, Ashutosh; Ammar, Mostafa (October 2020, 2020 IEEE 28th International Conference on Network Protocols (ICNP))

   null (Ed.)

   The coronavirus pandemic is altering our way of life. As more establishments open, there is an expectation that people will follow physical distancing guidelines. The implementation, however, is poor; just putting up warning signs appealing the general public to keep a distance of 6 feet from others is hardly enough. In this paper we consider the design of a wearable device that raises an alarm if another similar device is detected within a set distance. It uses off-the-shelf ultra-wideband radio technology for real-time, accurate distance estimation from others in the vicinity. We design an one-to-all ranging protocol that is able to accurately estimate distance to neighboring devices and warn the user if the distance falls below a certain established threshold within a short time. The device must compensate for human occlusions and avoid unnecessary warnings when physical barriers exist between devices. We implement and evaluate our protocol in a small testbed with custom prototype hardware as well as in simulation. Our ranging protocol is capable of performing up to 10 distance measurements per second, while avoiding packet collisions. The overall percentage of rangings completed is around 65% in a 10-node network, and the distance accuracy is around 20cm even with frequent human occlusions. We believe this prototype will provide the first steps to ensure physical distancing in various real-world settings. 

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2. A Phone in a Basket Looks Like a Knife in a Cup: Role-Filler Independence in Visual Processing

   https://doi.org/10.1162/opmi_a_00146  

   Hafri, Alon; Bonner, Michael F; Landau, Barbara; Firestone, Chaz (January 2024, Open Mind)

   Abstract When a piece of fruit is in a bowl, and the bowl is on a table, we appreciate not only the individual objects and their features, but also the relations containment and support, which abstract away from the particular objects involved. Independent representation of roles (e.g., containers vs. supporters) and “fillers” of those roles (e.g., bowls vs. cups, tables vs. chairs) is a core principle of language and higher-level reasoning. But does such role-filler independence also arise in automatic visual processing? Here, we show that it does, by exploring a surprising error that such independence can produce. In four experiments, participants saw a stream of images containing different objects arranged in force-dynamic relations—e.g., a phone contained in a basket, a marker resting on a garbage can, or a knife sitting in a cup. Participants had to respond to a single target image (e.g., a phone in a basket) within a stream of distractors presented under time constraints. Surprisingly, even though participants completed this task quickly and accurately, they false-alarmed more often to images matching the target’s relational category than to those that did not—even when those images involved completely different objects. In other words, participants searching for a phone in a basket were more likely to mistakenly respond to a knife in a cup than to a marker on a garbage can. Follow-up experiments ruled out strategic responses and also controlled for various confounding image features. We suggest that visual processing represents relations abstractly, in ways that separate roles from fillers. 

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3. A throughput optimal scheduling policy for a quantum switch

   https://doi.org/10.1117/12.2616950  

   Vasantam, Thirupathaiah; Towsley, Don (March 2022, Proceedings Volume 12015, Quantum Computing, Communication, and Simulation II;)

   Hemmer, Philip R.; Migdall, Alan L. (Ed.)

   We study a quantum switch that creates shared end-to-end entangled quantum states to multiple sets of users that are connected to it. Each user is connected to the switch via an optical link across which bipartite Bell-state entangled states are generated in each time-slot with certain probabilities, and the switch merges entanglements of links to create end-to-end entanglements for users. One qubit of an entanglement of a link is stored at the switch and the other qubit of the entanglement is stored at the user corresponding to the link. Assuming that qubits of entanglements of links decipher after one time-slot, we characterize the capacity region, which is defined as the set of arrival rates of requests for end-to-end entanglements for which there exists a scheduling policy that stabilizes the switch. We propose a Max-Weight scheduling policy and show that it stabilizes the switch for all arrival rates that lie in the capacity region. We also provide numerical results to support our analysis. 

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4. A note on a Newtonian approximation in a Schwarzschild background

   BENSON, B. A.; DISCONZI, M. M. (April 2018, African physical reviews)

   We consider a (very) simple version of the restricted three body problem in general relativity. The background geometry is given by a Schwarzschild solution governing the motion of two bodies of masses $$m_1$$ and $$m_2$$. We assume that corrections to the trajectory of the body of mass $$m_1$$ due to the presence of the mass $$m_2$$ are given by a Newtonian approximation where Poisson's equation is solved with respect to the Schwarzschild background geometry. Under these assumptions, we derive approximate equations of motion for the corrections to the trajectory of the body of mass $$m_1$$. 

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5. On the propulsion of a rigid body in a viscous liquid under the action of a time-periodic force

   https://doi.org/10.1007/s40687-025-00510-0  

   Galdi, Giovanni P; Karakouzian, Mher M (June 2025, Research in the Mathematical Sciences)

   Arigid body B moves in an otherwise quiescent viscous liquid filling the whole space outside B, under the action of a time-periodic force f of period T applied to a given point of B and of fixed direction. We assume that the average of f over an interval of length T does not vanish, and that the amplitude, δ,off is sufficiently small. Our goal is to investigate when B executes a nonzero net motion; that is, B is able to cover any prescribed distance in a finite time. We show that, at the order δ, this happens if and only if f and B satisfy a certain condition. We also show that this is always the case if B is prevented from spinning. Finally, we provide explicit examples where the condition above is satisfied or not. All our analysis is performed in a general class of weak solutions to the coupled system body-liquid problem. 

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