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James Wells

Publications and source records attributed to James Wells.

16 recordsLinked to original sources
arXiv2026

Pre-shipment optical characterization of the SCALES instrument

The Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy (SCALES) instrument is a 1-5 micron imager and 2-5 micron integral field spectrograph, currently being commissioned on the Keck II Telescope. SCALES is optimized for exoplanet high-contrast imaging and spectroscopic characterization, and will be sensitive to older, colder exoplanets than existing instrumentation. The 12.3" x 12.3" imaging channel is designed to replicate the capabilities of NIRC2, and the low (R~35-200, 2.2" x 2.2" FOV) and medium (R~2500-5000, 0.36" x 0.34" FOV) spectral resolution modes offer new capabilities compared to existing Keck instrumentation. We present preliminary optical performance results from laboratory testing and commissioning of SCALES.

astro-ph.IM↗
arXiv2026

LUCAID: Agentic Multimodal AI for Lung Cancer Precision Pathology

Lung cancer tissue diagnostics is complex, as therapy decisions in precision oncology rely on the integration of histomorphological, immunohistochemical, and molecular features. Yet pathological assessment remains largely visual and semi-quantitative and shows interobserver variability, while existing artificial intelligence (AI) tools cover only selected tasks, rarely reach generalizable expert-level performance, and lack prospective clinical validation. To address these challenges, we developed and clinically validated LUCAID, an agentic AI system for precision lung cancer pathology. An integrative agent couples diagnostic reasoning with nine modules that cover the full routine workflow, from quality control, tumor detection and segmentation, histological subtyping, tumor microenvironment profiling, tumor cellularity quantification, and predictive biomarker scoring (PD-L1, MET, TROP-2) to automated structured report generation. LUCAID enables users to interactively query the module outputs and generate reports that contextualize the results. Against large-scale expert ground-truth annotations, the analysis modules achieved F1 scores of 0.82-0.95. In prospective clinical validation, LUCAID reached 93.0% concordance with an expert-panel adjudicated reference standard across clinically actionable decisions, compared with 68.3-81.1% for five experienced thoracic pathologists.

cs.CV↗
arXiv2020

$|\Delta \mathcal{B}| =2$: A State of the Field, and Looking Forward--A brief status report of theoretical and experimental physics opportunities

The origin of the matter-antimatter asymmetry apparently obligates the laws of physics to include some mechanism of baryon number ($\mathcal{B}$) violation. Searches for interactions violating $\mathcal{B}$ and baryon-minus-lepton number $\mathcal{(B-L)}$ represent a rich and underutilized opportunity. These are complementary to the existing, broad program of searches for $\mathcal{L}$-violating modes such as neutrinoless double $\beta$-decay which could provide deeper understandings of the plausibility of leptogenesis, or $\mathcal{B}$-violating, $\mathcal{(B-L)}$-conserving processes such as proton decay. In particular, a low-scale, post-sphaleron violation mechanism of $\mathcal{(B-L)}$ could provide a \textit{testable} form of baryogenesis. Though theoretically compelling, searches for such $\mathcal{(B-L)}$-violating processes like $\Delta\mathcal{B}=2$ dinucleon decay and $n\rightarrow\bar{n}$ remain relatively underexplored experimentally compared to other rare processes. By taking advantage of upcoming facilities such as the Deep Underground Neutrino Experiment and the European Spallation Source, this gap can be addressed with new intranuclear and free searches for neutron transformations with very high sensitivity, perhaps greater than three orders of magnitude higher than previous experimental searches. This proceedings reports on recent theoretical and experimental advances and sensitivities of next-generation searches for neutron transformations were detailed as part of the Amherst Center for Fundamental Interactions Workshop, "Theoretical Innovations for Future Experiments Regarding Baryon Number Violation," directly coordinated with the Rare Processes and Precision Measurements Frontier.

hep-ph↗
arXiv2020

Lissajous scanning magnetic particle imaging as a multifunctional platform for magnetic hyperthermia therapy

The use of engineered nanoscale magnetic materials in healthcare and biomedical technologies is rapidly growing. Two examples which have recently attracted significant attention are magnetic particle imaging (MPI) for biological monitoring, and magnetic field hyperthermia (MFH) for cancer therapy. Here for the first time, the capability of a Lissajous scanning MPI device to act as a standalone platform to support the application of MFH cancer treatment is presented. The platform is shown to offer functionalities for nanoparticle localization, focused hyperthermia therapy application, and non-invasive tissue thermometry in one device. Combined, these capabilities have the potential to significantly enhance the accuracy, effectiveness and safety of MFH therapy. Measurements of nanoparticle hyperthermia during protracted exposure to the MPI scanner's 3D imaging field sequence revealed spatially focused heating, with a maximum that is significantly enhanced compared with a simple 1-dimensional sinusoidal excitation. The observed spatial heating behavior is qualitatively described based on a phenomenological model considering torques exerted in the Brownian regime. In-vitro cell studies using a human acute monocytic leukemia cell line (THP-1) demonstrated strong suppression of both structural integrity and metabolic activity within 24 h following a 40 min MFH treatment actuated within the Lissajous MPI scanner. Furthermore, reconstructed MPI images of the nanoparticles distributed among the cells, and the temperature-sensitivity of the MPI imaging signal obtained during treatment are demonstrated. In summary, combined Lissajous MPI and MFH technologies are presented; demonstrating for the first time their potential for cancer treatment with maximum effectiveness, and minimal collateral damage to surrounding tissues.

physics.med-ph↗
arXiv2020

Extending Modified Module Analysis to Include Correct Responses: An Analysis of the Force Concept Inventory

Brewe, Bruun, and Bearden first applied network analysis to understand patterns of incorrect conceptual physics reasoning in multiple-choice instruments introducing the Module Analysis for Multiple-Choice Responses (MAMCR) algorithm. Wells {\it et al.} proposed an extension to the algorithm which allowed the analysis of large datasets called Modified Module Analysis (MMA). This method analyzed the network structure of the correlation matrix of the responses to a multiple-choice instrument. Both MAMCR and MMA could only be applied to networks of incorrect responses. In this study, an extension of MMA is explored which allows the analysis of networks involving both correct and incorrect responses. The extension analyzes the network structure of the partial correlation matrix instead of the correlation matrix. The new algorithm, called MMA-P, was applied to the FCI and recovered much of the structure identified by MMA. The algorithm also identified sets of correct answers requiring similar physical reasoning reported in previous studies. Beyond groups of all correct and all incorrect responses, some groups of responses which mixed correct and incorrect responses were also identified. Some of these mixed response groups were produced when a correct response was selected for incorrect reasons; some of the groups helped to explain the gender unfairness previously reported for the FCI.

physics.ed-ph↗
arXiv2020

Exploring the Structure of Misconceptions in the Force and Motion Conceptual Evaluation with Modified Module Analysis

Investigating student learning and understanding of conceptual physics is a primary research area within Physics Education Research (PER). Multiple quantitative methods have been employed to analyze commonly used mechanics conceptual inventories: the Force Concept Inventory (FCI) and the Force and Motion Conceptual Evaluation (FMCE). Recently, researchers have applied network analytic techniques to explore the structure of the incorrect responses to the FCI identifying communities of incorrect responses which could be mapped on to common misconceptions. In this study, the method used to analyze the FCI, Modified Module Analysis (MMA), was applied to a large sample of FMCE pretest and post-test responses ($N_{pre}=3956$, $N_{post}=3719$). The communities of incorrect responses identified were consistent with the item groups described in previous works. As in the work with the FCI, the network was simplified by only retaining nodes selected by a substantial number of students. Retaining nodes selected by 20\% of the students produced communities associated with only four misconceptions. The incorrect response communities identified for men and women were substantially different, as was the change in these communities from pretest to post-test. The 20% threshold was far more restrictive than the 4% threshold applied to the FCI in the prior work which generated similar structures. Retaining nodes selected by 5% or 10% of students generated a large number of complex communities. The communities identified at the 10\% threshold were generally associated with common misconceptions producing a far richer set of incorrect communities than the FCI; this may indicate that the FMCE is a superior instrument for characterizing the breadth of student misconceptions about Newtonian mechanics.

physics.ed-ph↗
arXiv2019

3D-Imaging and Quantification of Magnetic Nanoparticle Uptake by Living Cells

Magnetic particle imaging (MPI) is a non-invasive, non-ionizing imaging technique for the visualization and quantification of magnetic nanoparticles (MNPs). The technique is especially suitable for cell imaging as it offers zero background contribution from the surrounding tissue, high sensitivity, and good spatial and temporal resolutions. Previous studies have demonstrated that the dynamic magnetic behaviour of MNPs changes during cellular binding and internalization. In this study, we demonstrate how this information is encoded in the MPI imaging signal. Through MPI imaging we are able to discriminate between free and cell-bound MNPs in reconstructed images. This technique was used to image and quantify the changes that occur in-vitro when free MNPs come into contact with cells and undergo cellularuptake over time. The quantitative MPI results were verified by a phenanthroline assay. The results showed a mean relative difference of 23.8% for the quantification of cell-bound MNPs. The insights gained from such observations provide a new window into fundamental biological processes and associated pathological changes occurring at a cellular level. This technique could therefore offer new opportunities for the early diagnosis of inflammatory diseases.

physics.med-ph↗
arXiv2019

European research on magnetic nanoparticles for biomedical applications: standardisation aspects

Magnetic nanoparticles have many applications in biomedicine and other technical areas. Despite their huge economic impact, there are no standardised procedures available to measure their basic magnetic properties. The International Organization for Standardization is working on a series of documents on the definition of characteristics of magnetic nanomaterials. We review previous and ongoing European research projects on characteristics of magnetic nanoparticles and present results of an online survey among European researchers.

physics.med-ph↗
arXiv2019

Exploring the Structure of Misconceptions in the Force Concept Inventory with Modified Module Analysis

Module Analysis for Multiple-Choice Responses (MAMCR) was applied to a large sample of Force Concept Inventory (FCI) pretest and post-test responses ($N_{pre}=4509$ and $N_{post}=4716$) to replicate the results of the original MAMCR study and to understand the origins of the gender differences reported in a previous study of this data set. When the results of MAMCR could not be replicated, a modification of the method was introduced, Modified Module Analysis (MMA). MMA was productive in understanding the structure of the incorrect answers in the FCI, identifying 9 groups of incorrect answers on the pretest and 11 groups on the post-test. These groups, in most cases, could be mapped on to common misconceptions used by the authors of the FCI to create distactors for the instrument. Of these incorrect answer groups, 6 of the pretest groups and 8 of the post-test groups were the same for men and women. Two of the male-only pretest groups disappeared with instruction while the third male-only pretest group was identified for both men and women post-instruction. Three of the groups identified for both men and women on the post-test were not present for either on the pretest. The rest of the identified incorrect answer groups did not represent misconceptions, but were rather related to the the blocked structure of some FCI items where multiple items are related to a common stem. The groups identified had little relation to the gender unfair items previously identified for this data set, and therefore, differences in the structure of student misconceptions between men and women cannot explain the gender differences reported for the FCI.

physics.ed-ph↗
arXiv2016

Nano scale thermo-electrical detection of magnetic domain wall propagation

In magnetic nanowires with perpendicular magnetic anisotropy (PMA) magnetic domain walls (DW) are narrow and can move rapidly driven by current induced torques. This enables important applications like high-density memories for which the precise detection of the position and motion of a propagating DW is of utmost interest. Today's DW detection tools are often limited in resolution, or acquisition speed, or can only be applied on specific materials. Here, we show that the anomalous Nernst effect provides a simple and powerful tool to precisely track the position and motion of a single DW propagating in a PMA nanowire. We detect field and current driven DW propagation in both metallic heterostructures and dilute magnetic semiconductors over a broad temperature range. The demonstrated spatial resolution below 20 nm is comparable to the DW width in typical metallic PMA systems.

cond-mat.mes-hall↗
arXiv2012

CLIC e+e- Linear Collider Studies

This document provides input from the CLIC e+e- linear collider studies to the update process of the European Strategy for Particle Physics. It is submitted on behalf of the CLIC/CTF3 collaboration and the CLIC physics and detector study. It describes the exploration of fundamental questions in particle physics at the energy frontier with a future TeV-scale e+e- linear collider based on the Compact Linear Collider (CLIC) two-beam acceleration technique. A high-luminosity high-energy e+e- collider allows for the exploration of Standard Model physics, such as precise measurements of the Higgs, top and gauge sectors, as well as for a multitude of searches for New Physics, either through direct discovery or indirectly, via high-precision observables. Given the current state of knowledge, following the observation of a \sim125 GeV Higgs-like particle at the LHC, and pending further LHC results at 8 TeV and 14 TeV, a linear e+e- collider built and operated in centre-of-mass energy stages from a few-hundred GeV up to a few TeV will be an ideal physics exploration tool, complementing the LHC. Two example scenarios are presented for a CLIC accelerator built in three main stages of 500 GeV, 1.4 (1.5) TeV, and 3 TeV, together with the layout and performance of the experiments and accompanied by cost estimates. The resulting CLIC physics potential and measurement precisions are illustrated through detector simulations under realistic beam conditions.

physics.acc-ph↗
arXiv2007

Narrow Trans-TeV Higgs Bosons and $H\to hh$ Decays: Two LHC Search Paths for a Hidden Sector Higgs Boson

We consider the addition of a condensing singlet scalar field to the Standard Model. Such a scenario may be motivated by any number of theoretical ideas, including the common result in string-inspired model building of singlet scalar fields charged under some hidden sector gauge symmetry. For concreteness, we specify an example model of this type, and consider the relevant constraints on Higgs physics, such as triviality, perturbative unitarity and precision electroweak analysis. We then show that there are two unique features of the phenomenology that present opportunities for discovery at the Large Hadron Collider (LHC). First, it is possible to identify and discover a narrow trans-TeV Higgs boson in this scenario -- a mass scale that is well above the scale at which it is meaningful to discuss a SM Higgs boson. Second, the decays of the heavier scalar state into the lighter Higgs bosons can proceed at a high rate and may be the first discovery mode in the Higgs sector.

hep-ph↗
arXiv2002

Experimental Approaches at Linear Colliders

This report summarises the activity of the E3 working group "Experimental Approaches at Linear Colliders". The group was charged with examining critically the physics case for a linear collider of energy of order 1 TeV as well as the cases for higher energy machines, assessing the performance requirements and exploring the viability of several special options. In addition it was asked to identify the critical areas where R&D is required.

hep-ex↗
arXiv2001

Superlight gravitinos in electron-photon collisions

Motivated by recent studies of supersymmetry in higher-dimensional spaces, we discuss the experimental signatures of a superlight gravitino, mass < 0.001 eV. We concentrate on the process (e- gamma -> selectronR gravitino) as a probe of supersymmetry, where a single heavy superpartner and a superlight gravitino are produced. The fact that there is only one heavy superpartner in the final state in this process would require a lower center-of-mass energy for on-shell production compared to conventional pair production. For instance, for a 500 GeV machine, we find that a positive signal will be found if the supersymmetry breaking scale is less than about 2 TeV. If no positive signal is found, this process puts a bound on the supersymmetry breaking scale.

hep-ph↗
arXiv2000

Detecting a light Higgs boson at the Fermilab Tevatron through enhanced decays to photon pairs

We analyze the prospects of the Tevatron for finding a Higgs boson in the two photon decay mode. We conclude that the Standard Model (SM) Higgs boson will likely not be discovered in this mode. However, we motivate several theories beyond the SM, including the MSSM, that predict a Higgs boson with enhanced branching fractions into photons, and calculate the luminosity needed to discover a general Higgs boson at the Tevatron by a two-photon invariant mass peak at large transverse momentum. We find that a high luminosity Tevatron will play a significant role in discovering or constraining these theories.

hep-ph↗