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This paper proposes an algorithm for synthesis of clock-follow-data designs that provides robustness against timing violations for RSFQ circuits while maintaining high performance and minimizing area costs. Since superconducting logic gates must be clocked, managing data flow is a challenging problem that often requires the insertion of many path balancing D Flips (DFFs) to properly sequence data, leading to a substantial increase in area. To address this challenge, we present an algorithm to insert DFFs into clock-follow-data RSFQ circuits that partially balances the delays within the circuit to achieve a target throughput while minimizing area. Our algorithm can account for expected timing variations and, by adjusting the bias of the clock network and clock frequency, we can mitigate unexpected timing violations post-fabrication. Quantifying the benefits of our approach with a benchmark suite with nominal delays, our designs offer an average 1.48x improvement in area delay product (ADP) over high frequency full path balancing (FPB) designs and a 2.07x improvement in ADP over the state of the art robust circuits provided by state-of-the-art (SOTA) multi-phase clocking solutions.

For an untilted Frenkel-Kontorova chain and any rational $p/q$, Aubry and Mather proved there are minimising equilibrium states that are left- and right-asymptotic to neighbouring pairs of spatially periodic minimisers of type $(p,q)$. They are known as {\em discommensurations} (or kinks or fronts), {\em advancing }if the right-asymptotic equilibrium is to the right of the left-asymptotic one, {\em retreating} otherwise. Following work of Middleton, Floria \& Mazo and Baesens \& MacKay, there is a threshold tilt $F_d(p/q)\ge 0$ up to which there continue to be periodic equilibria of type $(p,q)$ and above which there is a globally attracting periodically sliding solution in the space of sequences of type $(p,q)$. In this paper, we prove that there are values $F_d(p/q\pm)$ of tilt with $0\le F_d(p/q\pm) \le F_d(p/q)$, generically positive and less than $F_d(p/q)$, up to which there continue to be equilibrium advancing or retreating discommensurations, respectively, and such that for $F_d(p/q\pm) < F < F_d(p/q)$ there are periodically sliding discommensurations, apart perhaps from exceptional cases with both a degenerate type $(p,q)$ equilibrium and a degenerate advancing equilibrium discommensuration. We give examples, however, to show that equilibrium and periodically sliding discommensurations may co-exist, both above and below $F_d(p/q\pm)$, so the case of discommensurations is not as clean as that of periodic configurations. On the way, we prove that $F_d(\omega) \to F_d(p/q\pm)$ as $\omega \searrow p/q$ or $\nearrow p/q$ respectively. Finally, we prove that $F_d(p/q\pm)=0$ is equivalent to the existence of a rotational invariant circle consisting of periodic orbits of type $(p,q)$ and right-going (respectively left-going) separatrices, for the corresponding twist map on the cylinder., Comment: 50 pages

Cuvier's beaked whales (Ziphius cavirostris) are the deepest diving marine mammal, consistently diving to depths exceeding 1,000m for durations longer than an hour, making them difficult animals to study. They are important to study because they are sensitive to disturbances from naval sonar. Satellite-linked telemetry devices provide up to 14-day long records of dive behavior. However, the time series of depths is discretized to coarse bins due to bandwidth limitations. We analyze telemetry data from beaked whales that were exposed to moderate levels of sonar within controlled exposure experiments (CEEs) to study behavioral responses to sound exposure. We model the data as a hidden Markov model (HMM) over the time series of discrete depth bins, introducing partially observed movement types and recent diving activity covariates to model marginal non-stationarity. Movement types provide more flexible modeling for CEEs than partially observed dive stages, which are more commonly used in dive behavior HMMs. We estimate the proposed model within a hierarchical Bayesian framework, using HMM methods to compute marginalized likelihoods and posterior predictive distributions. We assess behavioral response by comparing observed post-exposure behavior to usual unexposed behavior via the posterior predictive distribution. The model quantifies patterns in baseline diving behavior and finds evidence that beaked whales deviate in response to sound. We find evidence that (i) beaked whales initially shorten the time they spend between deep dives, which may have physiological effects and (ii) subsequently avoid deep dives, which can result in lost foraging opportunities., Comment: 23 pages, 7 figures, 1 table

Feature selection is vital for identifying relevant variables in classification and regression models, especially in single-cell RNA sequencing (scRNA-seq) data analysis. Traditional methods like LASSO often struggle with the nonlinearities and multicollinearities in scRNA-seq data due to complex gene expression and extensive gene interactions. Quantum annealing, a form of quantum computing, offers a promising solution. In this study, we apply quantum annealing-empowered quadratic unconstrained binary optimization (QUBO) for feature selection in scRNA-seq data. Using data from a human cell differentiation system, we show that QUBO identifies genes with nonlinear expression patterns related to differentiation time, many of which play roles in the differentiation process. In contrast, LASSO tends to select genes with more linear expression changes. Our findings suggest that the QUBO method, powered by quantum annealing, can reveal complex gene expression patterns that traditional methods might overlook, enhancing scRNA-seq data analysis and interpretation.

This work explores the conditions under which global contraction manifests in the leaky continuous time reservoirs, thus guaranteeing Generalized Synchronization. Results on continuous time reservoirs make use of the logarithmic norm of the connectivity matrix. Further analysis yields some simple guidelines on how to better construct the connectivity matrix in these systems. Additionally, we outline how the Universal Approximation Property of discrete time reservoirs is readily satisfied by virtue of the activation function being contracting, and how continuous time reservoirs may inherit a limited form of universal approximation by virtue of them overlapping with Neural Ordinary Differential Equations. The ability of the Reservoir Computing framework to universally approximate topological conjugates, along with their fast training, make them a compelling data-driven, black-box surrogate of dynamical systems, and a potential mechanism for developing digital twins.

Spatially-resolved heating and cooling in nanostructures is nowadays measured with various nanoscale thermometry techniques, including scanning thermometry. Yet the most commonly used theory of nanoscale heating and thermoelectricity -- Landauer scattering theory -- is not appropriate to model such measurements. Hence, we analyze a minimal model of spatially-resolved heat transfer between electrons and phonons in simple thermoelectric nanostructures. This combines Landauer scattering formalism with a Boltzmann equation for transport, revealing the non-locality of Joule heating and Peltier cooling induced by a scatterer in a nanowire. The corresponding heating or cooling of the phonons is caused by the voltage drop at the scatterer, but is often maximal at a certain distance from the scatterer. This distance is of the order of the electron-phonon scattering length. Scanning thermal microscopy, such as SQUID-on-tip thermometers, should detect this non-locality as phonon hot spots and cold spots, spatially separated from the scatterer. We provide physical arguments explaining the thermoelectric response of the combined system of wire and scatterer, and in particular, why the resulting heating and cooling is sometimes the opposite to that predicted by the standard Landauer scattering theory., Comment: Version 2: added 2 references, some other very minor improvements

The paper describes ways that the computation of the volume enclosed by an invariant torus (flux surface) for a magnetic field can be reduced from a 3D integral to a 2D integral.

Perfect colouring of isonemal fabrics by thin and thick striping of warp and weft with more than two colours is examined where the cells with warps and wefts of the same colour do not appear along diagonal lines (not twilly redundancy). In species 33 to 39, all fabrics of specific orders (linear periods) can be perfectly coloured by thin striping with satin redundancy. In fewer species, all fabrics of specific orders can be perfectly coloured by thick striping in two different ways with doubled satin redundancy. The isonemal fabric 6-1-1 can be used as a redundancy configuration. All these colourings allow the coloured weaving of flat tori and -- a few of them -- cubes.

In this article, the effect a moving target has on the signal-to-interference-plus-noise-ratio (SINR) for high time-bandwidth noise radars is investigated. To compensate for cell migration we apply a computationally efficient stretch processing algorithm that is tailored for batched processing and suitable for implementation onto a real-time radar processor. The performance of the algorithm is studied using experimental data. In the experiment, pseudorandom noise, with a bandwidth of 100 MHz, is generated and transmitted in real-time. An unmanned aerial vehicle (UAV), flown at a speed of 11 m/s, is acting as a target. For an integration time of 1 s, the algorithm is shown to yield an increase in SINR of roughly 13 dB, compared to no compensation. It is also shown that coherent integration times of 2.5 s can be achieved., Comment: Presented at 2023 20th European Radar Conference (EuRAD)

We consider Riesz energy problems with radial external fields. We study the question of whether or not the equilibrium is the uniform distribution on a sphere. We develop general necessary as well as general sufficient conditions on the external field that apply to powers of the Euclidean norm as well as certain Lennard--Jones type fields. Additionally, in the former case, we completely characterize the values of the power for which dimension reduction occurs in the sense that the support of the equilibrium measure becomes a sphere. We also briefly discuss the relation between these problems and certain constrained optimization problems. Our approach involves the Frostman characterization, the Funk--Hecke formula, and the calculus of hypergeometric functions., Comment: 34 pages, 6 figures

Sound is assumed to be the primary modality of communication among marine mammal species. Analyzing acoustic recordings helps to understand the function of the acoustic signals as well as the possible impact of anthropogenic noise on acoustic behavior. Motivated by a dataset from a network of hydrophones in Cape Cod Bay, Massachusetts, utilizing automatically detected calls in recordings, we study the communication process of the endangered North Atlantic right whale. For right whales an "up-call" is known as a contact call, and ensuing counter-calling between individuals is presumed to facilitate group cohesion. We present novel spatiotemporal excitement modeling consisting of a background process and a counter-call process. The background process intensity incorporates the influences of diel patterns and ambient noise on occurrence. The counter-call intensity captures potential excitement, that calling elicits calling behavior. Call incidence is found to be clustered in space and time; a call seems to excite more calls nearer to it in time and space. We find evidence that whales make more calls during twilight hours, respond to other whales nearby, and are likely to remain quiet in the presence of increased ambient noise.

We present and discuss the results of a qualitative analysis of visual representations from images. We labeled each image's essential stimuli, the removal of which would render a visualization uninterpretable. As a result, we derive a typology of 10 visualization types of defined groups. We describe the typology derivation process in which we engaged. The resulting typology and image analysis can serve a number of purposes: enabling researchers to study the evolution of the community and its research output over time, facilitating the categorization of visualization images for the purpose of research and teaching, allowing researchers and practitioners to identify visual design styles to further align the quantification of any visual information processor, be that a person or an algorithm observer, and it facilitates a discussion of standardization in visualization. In addition to the visualization typology from images, we provide a dataset of 6,833 tagged images and an online tool that can be used to explore and analyze the large set of labeled images. The tool and data set enable scholars to closely examine the diverse visual designs used and how they are published and communicated in our community. A pre-registration, a free copy of this paper, and all supplemental materials are available via osf.io/dxjwt., Comment: arXiv admin note: text overlap with arXiv:2209.07533

Mini-magnetospheres are small ion-scale structures that are well-suited to studying kinetic-scale physics of collisionless space plasmas. Such ion-scale magnetospheres can be found on local regions of the Moon, associated with the lunar crustal magnetic field. In this paper, we report on the laboratory experimental study of magnetic reconnection in laser-driven, lunar-like ion-scale magnetospheres on the Large Plasma Device (LAPD) at the University of California - Los Angeles. In the experiment, a high-repetition rate (1 Hz), nanosecond laser is used to drive a fast moving, collisionless plasma that expands into the field generated by a pulsed magnetic dipole embedded into a background plasma and magnetic field. The high-repetition rate enables the acquisition of time-resolved volumetric data of the magnetic and electric fields to characterize magnetic reconnection and calculate the reconnection rate. We notably observe the formation of Hall fields associated with reconnection. Particle-in-cell simulations reproducing the experimental results were performed to study the micro-physics of the interaction. By analyzing the generalized Ohm's law terms, we find that the electron-only reconnection is driven by kinetic effects, through the electron pressure anisotropy. These results are compared to recent satellite measurements that found evidence of magnetic reconnection near the lunar surface.

Adiabatic Quantum-Flux-Parametron (AQFP) logic is a promising emerging device technology with six orders of magnitude lower power than CMOS. However, AQFP is challenged by the fact that every gate must be clocked, where proper data transfer requires connected gates to have shifted but overlapping clocks. As a result, buffers need to be used to balance re-convergent logic paths, a problem that is exacerbated by every multi-node fanout needing a tree of clocked splitters. Recent AQFP circuit design techniques have offered an opportunity to reduce buffer costs by supporting a notion of phase-skipping but the EDA support for these advanced circuits is limited. This paper proposes the first algorithm to optimize buffer and splitter insertion for phase-skipping AQFP circuits and achieves over 31\% savings over existing buffer reduction schemes and up to 74\% savings in buffers and splitter costs over the SOTA non-phase skipping circuits.

A key distinguishing feature of single flux quantum (SFQ) circuits is that each logic gate is clocked. This feature forces the introduction of path-balancing flip-flops to ensure proper synchronization of inputs at each gate. This paper proposes a polynomial time complexity approximation algorithm for clocking assignments that minimizes the insertion of path balancing buffers for multi-threaded multi-phase clocking of SFQ circuits. Existing SFQ multi-phase clocking solutions have been shown to effectively reduce the number of required buffers inserted while maintaining high throughput, however, the associated clock assignment algorithms have exponential complexity and can have prohibitively long runtimes for large circuits, limiting the scalability of this approach. Our proposed algorithm is based on a linear program (LP) that leads to solutions that are experimentally on average within 5% of the optimum and helps accelerate convergence towards the optimal integer linear program (ILP) based solution. The improved LP and ILP runtimes permit multi-phase clocking schemes to scale to larger SFQ circuits than previous state of the art clocking assignment methods. We further extend the existing algorithm to support fanout sharing of the added buffers, saving, on average, an additional 10% of the inserted DFFs. Compared to traditional full path balancing (FPB) methods across 10 benchmarks, our enhanced LP saves 79.9%, 87.8%, and 91.2% of the inserted buffers for 2, 3, and 4 clock phases respectively. Finally, we extend this approach to the generation of circuits that completely mitigate potential hold-time violations at the cost of either adding on average less than 10% more buffers (for designs with 3 or more clock phases) or, more generally, adding a clock phase and thereby reducing throughput.

Using hybrid molecular dynamics/SWAP Monte Carlo (MD/SMC) simulations, we show that the terminal relaxation times $\tau$ for FIRE energy minimization of soft-sphere glasses exhibit thermal onset as samples become increasingly well-equilibrated. Although $\tau(\phi)$ can decrease by orders of magnitude as equilibration proceeds and the jamming density $\phi_{\rm J}$ increases via thermal onset, it always scales as $\tau(\phi) \sim (\phi_{\rm J} - \phi)^{-2} \sim [Z_{\rm iso} - Z_{\rm ms}(\tau)]^{-2}$, where $\phi_{\rm J}$ is the jamming density and $Z_{\rm ms}(\tau)$ is the average coordination number of particles satisfying a minimal local mechanical stability criterion ($Z \geq d+1$) at the top of the final potential-energy-landscape (PEL) sub-basin the system encounters. This scaling allows us to collapse $\tau$ datasets that look very different when plotted as a function of $\phi$, and to address a closely related question: how does the character of the PEL basins that dense thermal glasses most typically occupy evolve as the glasses age at constant $\phi$ and $T$?, Comment: resubmitted in response to referee comments

Fibromyalgia is a complicated and multifaceted disorder marked by widespread chronic pain, fatigue, and muscle tenderness. Current explanations for the pathophysiology of this condition include the Central Sensitization Theory, Cytokine Inflammation Theory, Muscle Hypoxia, Muscle Tender Point Theory, and Small Fiber Neuropathy Theory. The objective of this review article is to examine and explain each of these current theories and to provide a background on our current understanding of fibromyalgia. The medical literature on this disorder, as well as on the roles of functional magnetic resonance imaging (fMRI) and elastography as diagnostic tools, was reviewed from the 1970s to early 2023, primarily using the PubMed database. Five prominent theories of fibromyalgia etiology were examined: 1) Central Sensitization Theory; 2) Cytokine Inflammation Theory; 3) Muscle Hypoxia; 4) Muscle Tender Point Theory; and 5) Small Fiber Neuropathy Theory. Previous fMRI studies of FMS have revealed two key findings. First, patients with FMS show altered activation patterns in brain regions involved in pain processing. Second, the connectivity between brain structures in individuals diagnosed with FMS and healthy controls is different. Both of these findings will be expanded upon in this paper. The article also explores the potential for future research in fibromyalgia due to the advancements in fMRI and elastography techniques, such as shear wave ultrasound. Increased understanding of the underlying mechanisms contributing to fibromyalgia symptoms is necessary for improved diagnosis and treatment, and advanced imaging techniques can aid in this process.

We report the first observation of homogeneous crystallization in simulated high-dimensional ($d > 3$) liquids that follow physically realistic dynamics and have system sizes that are large enough to eliminate the possibility that crystallization was induced by the periodic boundary conditions. Supercooled four-dimensional (4D) Lennard-Jones liquids maintained at zero pressure and constant temperatures $0.59 < T < 0.63$ crystallized within $\sim 2 \times 10^4\tau$, where $\tau$ is the LJ time unit. WCA liquids that were maintained at the same densities and temperatures at which their LJ counterparts nucleated did not crystallize even after $2.5\times 10^5\tau$, showing that the presence of long-ranged attractive interactions dramatically speeds up 4D crystallization, much as it does in 3D. However, the overlap of the liquid and crystalline phases' local-bond-order distributions is much smaller for LJ than for WCA systems, which is the opposite of the 3D trend. This implies that the widely accepted hypothesis that increasing geometrical frustration rapidly suppresses crystallization as the spatial dimension $d$ increases is only generally valid in the absence of attractive interparticle forces.

Flat bands coupled with magnetism and topological orders near or at the Fermi level are well known to drive exotic correlation physics and unconventional superconductivity. Here, based on first-principles modeling combined with an in-depth symmetry analysis, we reveal the presence of topological flat bands involving low-energy Ni-$3d_{z^2}$ states in the recently discovered superconductor LaNiO$_{2}$. Our analysis demonstrates that LaNiO$_2$ is an Axion insulator with $\mathbb{Z}_{4} = 2$ and that it supports topological crystalline insulating states protected by the glide mirror symmetries. The topological flat bands in LaNiO$_{2}$ are also shown to host odd-parity superconductivity. Our study indicates that the nickelates would provide an interesting materials platform for exploring the interplay of flat bands, topological states, and superconductivity., Comment: 8, 3 figures, 1 table