arXiv subjects

Jason Smith

Publications and source records attributed to Jason Smith.

16 recordsLinked to original sources

arXiv2026

From Human Factors to Human-Technology Factors: An HCI Perspective on Technology in Avalanche Safety

The avalanche safety literature has identified human factors that contribute to accidents, yet researchers note a persistent gap between these insights and effective product design. Meanwhile, interactive technologies are shaping backcountry decision making with or without grounding in theory and research. We broaden the discussion of human factors into ``human-technology factors," examining how technology can both support and undermine judgment in avalanche terrain, from a human-computer interaction (HCI) perspective. We summarize relevant HCI concepts along four dimensions - attention, cognition, trust, and social interaction - and use them to revisit McCammon's FACETS framework, cataloging ways in which specific technologies may mitigate or exacerbate classic heuristic traps, grounded in accident reports and literature where possible. We identify recurring patterns, including technologies with dual-sided effects and a pervasive ``digital expert halo."

cs.HC↗

arXiv2025

Scalable registration of single quantum emitters within solid immersion lenses through femtosecond laser writing

The precise registration of solid-state quantum emitters to photonic structures is a major technological challenge for fundamental research (e.g. in cavity quantum electrodynamics) and applications to quantum technology. Standard approaches include the complex multi-step fabrication of photonic structures on pre-existing emitters, both registered within a grid of lithographically-defined markers. Here, we demonstrate a marker-free, femtosecond laser writing technique to generate individual quantum emitters within photonic structures. Characterization of 28 defect centers, laser-written at the centers of pre-existing solid immersion lens structures, showed offsets relative to the photonic structure's center of 260~nm in the x-direction and 60~nm in the y-direction, with standard deviations of $\pm 170$~nm and $\pm 90$~nm, respectively, resulting in an average 4.5 times enhancement of the optical collection efficiency. This method is scalable for developing integrated quantum devices using spin-photon interfaces in silicon carbide and is easily extendable to other materials.

quant-ph↗

arXiv2025

A Hodge-FAST Framework for High-Resolution Dynamic Functional Connectivity Analysis of Higher Order Interactions in EEG Signals

We introduce a novel framework that integrates Hodge decomposition with Filtered Average Short-Term (FAST) functional connectivity to analyze dynamic functional connectivity (DFC) in EEG signals. This method leverages graph-based topology and simplicial analysis to explore transient connectivity patterns at multiple scales, addressing noise, sparsity, and computational efficiency. The temporal EEG data are first sparsified by keeping only the most globally important connections, instantaneous connectivity at these connections is then filtered by global long-term stable correlations. This tensor is then decomposed into three orthogonal components to study signal flows over higher-order structures such as triangle and loop structures. Our analysis of Alzheimer-related MCI patients show significant temporal differences related to higher-order interactions that a pairwise analysis on its own does not implicate. This allows us for the first time to capture higher-dimensional interactions at high temporal resolution in noisy EEG signal recordings.

eess.SP↗

arXiv2024

Shape Measurement of Single Gold Nanorods in Water Using Open-access Optical Microcavities

Shape measurement of rod-shaped particles in fluids is an outstanding challenge with applications in characterising synthetic functional nanoparticles and in early warning detection of rod-shaped pathogens in water supplies. However, it is challenging to achieve accurate and real-time measurements at a single particle scale in solution with existing methods. Here we introduce a novel technique to measure the aspect ratio of rod-shaped particles by analysing changes in the polarisation state of a laser beam transmitted through an optical microcavity through which the particle diffuses. The resolution in aspect ratio measurement is found to be around 1%. Our work opens the new possibility of in-situ and single-particle shape measurements, which have promising applications in nanoparticle characterisation, water monitoring, and beyond.

physics.optics↗

arXiv2023

Dynamic Training of Liquid State Machines

Spiking Neural Networks (SNNs) emerged as a promising solution in the field of Artificial Neural Networks (ANNs), attracting the attention of researchers due to their ability to mimic the human brain and process complex information with remarkable speed and accuracy. This research aimed to optimise the training process of Liquid State Machines (LSMs), a recurrent architecture of SNNs, by identifying the most effective weight range to be assigned in SNN to achieve the least difference between desired and actual output. The experimental results showed that by using spike metrics and a range of weights, the desired output and the actual output of spiking neurons could be effectively optimised, leading to improved performance of SNNs. The results were tested and confirmed using three different weight initialisation approaches, with the best results obtained using the Barabasi-Albert random graph method.

cs.NE↗

arXiv2022

Real-time adaptive estimation of decoherence timescales for a single qubit

Characterising the time over which quantum coherence survives is critical for any implementation of quantum bits, memories and sensors. The usual method for determining a quantum system's decoherence rate involves a suite of experiments probing the entire expected range of this parameter, and extracting the resulting estimation in post-processing. Here we present an adaptive multi-parameter Bayesian approach, based on a simple analytical update rule, to estimate the key decoherence timescales ($T_1$, $T_2^*$ and $T_2$) and the corresponding decay exponent of a quantum system in real time, using information gained in preceding experiments. This approach reduces the time required to reach a given uncertainty by a factor up to an order of magnitude, depending on the specific experiment, compared to the standard protocol of curve fitting. A further speed-up of a factor $\sim 2$ can be realised by performing our optimisation with respect to sensitivity as opposed to variance.

quant-ph↗

arXiv2019

Learning from History: Recreating and Repurposing Sister Harriet Padberg's Computer Composed Canon and Free Fugue

Harriet Padberg wrote Computer-Composed Canon and Free Fugue as part of her 1964 dissertation in Mathematics and Music at Saint Louis University. This program is one of the earliest examples of text-to-music software and algorithmic composition, which are areas of great interest in the present-day field of music technology. This paper aims to analyze the technological innovation, aesthetic design process, and impact of Harriet Padberg's original 1964 thesis as well as the design of a modern recreation and utilization, in order to gain insight to the nature of revisiting older works. Here, we present our open source recreation of Padberg's program with a modern interface and, through its use as an artistic tool by three composers, show how historical works can be effectively used for new creative purposes in contemporary contexts. Not Even One by Molly Jones draws on the historical and social significance of Harriet Padberg through using her program in a piece about the lack of representation of women judges in composition competitions. Brevity by Anna Savery utilizes the original software design as a composition tool, and The Padberg Piano by Anthony Caulkins uses the melodic generation of the original to create a software instrument.

cs.MM↗

arXiv2019

Computing persistent homology of directed flag complexes

We present a new computing package Flagser, designed to construct the directed flag complex of a finite directed graph, and compute persistent homology for flexibly defined filtrations on the graph and the resulting complex. The persistent homology computation part of Flagser is based on the program Ripser [Bau18a], but is optimized specifically for large computations. The construction of the directed flag complex is done in a way that allows easy parallelization by arbitrarily many cores. Flagser also has the option of working with undirected graphs. For homology computations Flagser has an Approximate option, which shortens compute time with remarkable accuracy. We demonstrate the power of Flagser by applying it to the construction of the directed flag complex of digital reconstructions of brain microcircuitry by the Blue Brain Project and several other examples. In some instances we perform computation of homology. For a more complete performance analysis, we also apply Flagser to some other data collections. In all cases the hardware used in the computation, the use of memory and the compute time are recorded.

math.AT↗

arXiv2017

Lithium-loaded scintillators coupled to a custom-designed silicon photomultiplier array for neutron and gamma-ray detection

Scintillators capable of detecting both neutrons and gamma-rays have generated considerable interest. In particular, the use of such scintillators with silicon photomultipliers (SiPMs) enables low-power and compact-geometry applications. Three types of Li-loaded scintillators, CLYC, CLLB, and NaIL, have been tested with a custom-designed SiPM array for temperatures between --20 and 50$^{\circ}$C. The array consists of four 6x6~mm$^2$ SiPMs arranged in a 2x2 configuration. Pulse shape discrimination is used for neutron and gamma identification. Because the pulse shape changes with temperature, the quality of neutron and gamma discrimination varies with temperature. Furthermore, the larger dark current in SiPMs at high temperatures results in poorer energy resolution and neutron-gamma discrimination. Comparison of the energy resolution and the neutron-gamma discrimination for the three scintillators coupled to the custom SiPM array will be discussed.

physics.ins-det↗

arXiv2016

Scintillation detectors constructed with an optimized 2x2 silicon photomultiplier array

Silicon photomultipliers (SiPMs) are a good alternative to photomultiplier tubes (PMTs) because their gain and quantum efficiency are comparable to PMTs. However, the largest single-chip SiPM is still less than 1~cm$^2$. In order to use SiPMs with scintillators that have reasonable sensitivity, it is necessary to use multiple SiPMs. In this work, scintillation detectors are constructed and tested with a custom 2x2 SiPM array. The layout of the SiPMs and the geometry of the scintillator were determined by performing Geant4 simulations. Cubic NaI, CsI, and CLYC with 18~mm sides have been tested. The output of the scintillation detectors are stabilized over the temperature range between --20 and 50~$^{\circ}$C by matching the gain of the SiPMs in the array. The energy resolution for these detectors has been measured as a function of temperature. Furthermore, neutron detection for the CLYC detector was studied in the same temperature range. Using pulse-shape discrimination, neutrons can be cleanly identified without contribution from $\gamma$-photons. As a result, these detectors are suitable for deploying in spectroscopic personal radiation detectors (SPRD).

physics.ins-det↗

arXiv2016

Google's Neural Machine Translation System: Bridging the Gap between Human and Machine Translation

Neural Machine Translation (NMT) is an end-to-end learning approach for automated translation, with the potential to overcome many of the weaknesses of conventional phrase-based translation systems. Unfortunately, NMT systems are known to be computationally expensive both in training and in translation inference. Also, most NMT systems have difficulty with rare words. These issues have hindered NMT's use in practical deployments and services, where both accuracy and speed are essential. In this work, we present GNMT, Google's Neural Machine Translation system, which attempts to address many of these issues. Our model consists of a deep LSTM network with 8 encoder and 8 decoder layers using attention and residual connections. To improve parallelism and therefore decrease training time, our attention mechanism connects the bottom layer of the decoder to the top layer of the encoder. To accelerate the final translation speed, we employ low-precision arithmetic during inference computations. To improve handling of rare words, we divide words into a limited set of common sub-word units ("wordpieces") for both input and output. This method provides a good balance between the flexibility of "character"-delimited models and the efficiency of "word"-delimited models, naturally handles translation of rare words, and ultimately improves the overall accuracy of the system. Our beam search technique employs a length-normalization procedure and uses a coverage penalty, which encourages generation of an output sentence that is most likely to cover all the words in the source sentence. On the WMT'14 English-to-French and English-to-German benchmarks, GNMT achieves competitive results to state-of-the-art. Using a human side-by-side evaluation on a set of isolated simple sentences, it reduces translation errors by an average of 60% compared to Google's phrase-based production system.

cs.CL↗

arXiv2015

Information equilibrium as an economic principle

A general information equilibrium model in the case of ideal information transfer is defined and then used to derive the relationship between supply (information destination) and demand (information source) with the price as the detector of information exchange between demand and supply. We recover the properties of the traditional economic supply-demand diagram. Information equilibrium is then applied to macroeconomic problems, recovering some common macroeconomic models in particular limits like the AD-AS model, IS-LM model (in a low inflation limit), the quantity theory of money (in a high inflation limit) and the Solow-Swan growth model. Information equilibrium results in empirically accurate models of inflation and interest rates, and can be used to motivate a 'statistical economics', analogous to statistical mechanics for thermodynamics.

econ.GN↗

arXiv2008

Program for calculating bounds on the minimum rank of a graph using Sage

math.CO↗

arXiv2008

Table of minimum ranks of graphs of order at most 7 and selected optimal matrices

The minimum rank of a simple graph $G$ is defined to be the smallest possible rank over all symmetric real matrices whose $ij$th entry (for $i\neq j$) is nonzero whenever $\{i,j\}$ is an edge in $G$ and is zero otherwise. Minimum rank is a difficult parameter to compute. However, there are now a number of known reduction techniques and bounds that can be programmed on a computer; we have developed a program using the open-source mathematics software Sage to implement several techniques. We have also established several additional strategies for computation of minimum rank. These techniques have been used to determine the minimum ranks of all graphs of order 7. This paper contains a list of minimum ranks for all graphs of order at most 7. We also present selected optimal matrices.

math.CO↗

arXiv2004

Quantum Process

The exact scattering solutions of the Klein-Gordon equation in cylindrically symmetric field are constructed as eigenfunctions of a complete set of commuting operators. The matrix elements and the corresponding differential scattering cross-section are calculated. Properties of the pair production at various limits are discussed.

quant-ph↗

arXiv2003

GridMonitor: Integration of Large Scale Facility Fabric Monitoring with Meta Data Service in Grid Environment

Grid computing consists of the coordinated use of large sets of diverse, geographically distributed resources for high performance computation. Effective monitoring of these computing resources is extremely important to allow efficient use on the Grid. The large number of heterogeneous computing entities available in Grids makes the task challenging. In this work, we describe a Grid monitoring system, called GridMonitor, that captures and makes available the most important information from a large computing facility. The Grid monitoring system consists of four tiers: local monitoring, archiving, publishing and harnessing. This architecture was applied on a large scale linux farm and network infrastructure. It can be used by many higher-level Grid services including scheduling services and resource brokering.

cs.DC↗