UC Santa Cruz Previously Published Works

Total Cost of Ownership and Evaluation of Google Cloud Resources for the ATLAS Experiment at the LHC

(2025)

Abstract: The ATLAS Google Project was established as part of an ongoing evaluation of the use of commercial clouds by the ATLAS Collaboration, in anticipation of the potential future adoption of such resources by WLCG grid sites to fulfil or complement their computing pledges. Seamless integration of Google cloud resources into the worldwide ATLAS distributed computing infrastructure was achieved at large scale and for an extended period of time, and hence cloud resources are shown to be an effective mechanism to provide additional, flexible computing capacity to ATLAS. For the first time a total cost of ownership analysis has been performed, to identify the dominant cost drivers and explore effective mechanisms for cost control. Network usage significantly impacts the costs of certain ATLAS workflows, underscoring the importance of implementing such mechanisms. Resource bursting has been successfully demonstrated, whilst exposing the true cost of this type of activity. A follow-up to the project is underway to investigate methods for improving the integration of cloud resources in data-intensive distributed computing environments and reducing costs related to network connectivity, which represents the primary expense when extensively utilising cloud resources.

Quantifying local fishing mortality rates to inform monitoring design for marine reserves

(2025)

In the spatial management of marine resources, there are a variety of contexts in which it is valuable to estimate local, site-specific demographic rates, particularly harvest rates. For example, in the case of no-take marine reserves, estimating the fishing mortality rate (F) prior to reserve implementation can inform quantitative expectations for increases in the abundance of protected populations in the reserve. Additionally, estimating F after implementation could be used to detect poaching. Often the data available for these estimates are length-abundance survey data, such as from visual diver or camera surveys. One can estimate F by fitting models to population size-structure data; understanding how the accuracy of such estimates depends on sampling effort and fish life history can inform monitoring approaches. Here, we quantified the capacity of a state-space integral projection model (SS-IPM) to estimate local F, and how that depends on life history, the true value of F, and monitoring sampling design. We found that estimates of F were (a) more accurate for species with lower natural mortality rates and (b) less precise for higher values of F. Yet, with enough sampling effort, estimates of F were generally within 10% of the true value. In general, estimating local F reliably requires sampling ≥ 100 fish each year over at least 12–15 years. We used empirical data from California to illustrate these general results, which could inform adaptive management plans for other marine reserves globally.

Cover page of Rapid synthesis of single-layer iron-doped 2H tungsten sulfide via magnetic induction heating for piezocatalytic reduction of oxygen to hydrogen peroxide

Rapid synthesis of single-layer iron-doped 2H tungsten sulfide via magnetic induction heating for piezocatalytic reduction of oxygen to hydrogen peroxide

(2025)

Transition metal dichalcogenides have been attracting extensive attention as effective piezocatalysts for a wide range of applications, in particular, environmental remediation. Herein, WS2 nanoflowers with 2H-rich ultrathin petals are prepared by rapid synthesis based on magnetic induction heating (MIH) of sodium tungstate and thiourea, and the 2H phase is further enriched by Fe doping, in contrast to conventional pyrolysis that produces largely 1 T phase. Among the series, the sample prepared at 400 A for 10 s with an iron loading of ca. 0.1 wt% (3-Fe/WS2-400) exhibits the strongest piezoelectric response and greatest catalytic activity towards the selective reduction of oxygen to hydrogen peroxide under ultrasonic irradiation, reaching an ultrahigh H2O2 generation rate of 4.68 mM g⁻¹ h⁻¹, over 47 times higher than that of bulk-like WS₂. This is due to enhanced adsorption of O2 and manipulation of the electronic band structure by Fe doping that becomes favorable for oxygen reduction to H2O2, as manifested in theoretical studies based on density functional theory calculations. This unique property can be exploited for environmental remediation, as exemplified in the effective degradation of a range of organic pollutants. Results from this study highlight the unique potential of MIH in the structural engineering of functional nanomaterials for sustainable energy technologies.

Observation of VVZ production at s = 13 TeV with the ATLAS detector

(2025)

A search for the production of three massive vector bosons, VVZ(V=W,Z), in proton–proton collisions at s=13 TeV is performed using data with an integrated luminosity of 140 fb−1 recorded by the ATLAS detector at the Large Hadron Collider. Events produced in the leptonic final states WWZ→ℓνℓνℓℓ (ℓ=e,μ), WZZ→ℓνℓℓℓℓ, ZZZ→ℓℓℓℓℓℓ, and the semileptonic final states WWZ→qqℓνℓℓ and WZZ→ℓνqqℓℓ, are analysed. The measured cross section for the pp→VVZ process is 660−90+93(stat.)−81+88(syst.) fb, and the observed (expected) significance is 6.4 (4.7) standard deviations, representing the observation of VVZ production. In addition, the measured cross section for the pp→WWZ process is 442±94(stat.)−52+60(syst.) fb, and the observed (expected) significance is 4.4 (3.6) standard deviations, representing evidence of WWZ production. The measured cross sections are consistent with the Standard Model predictions. Constraints on physics beyond the Standard Model are also derived in the effective field theory framework by setting limits on Wilson coefficients for dimension-8 operators describing anomalous quartic gauge boson couplings.

A Living Experiment in Concept Formation: Hacking on the Creation of a Language for Autistic Experience

Dinishak, Janette

(2025)

Reference genome of the kidnapper ant, Polyergus mexicanus

(2025)

Polyergus kidnapper ants are widely distributed, but relatively uncommon, throughout the Holarctic, spanning an elevational range from sea level to over 3000 m. These species are well known for their obligate social parasitism with various Formica ant species, which they kidnap in dramatic, highly coordinated raids. Kidnapped Formica larvae and pupae become integrated into the Polyergus colony where they develop into adults and perform nearly all of the necessary colony tasks for the benefit of their captors. In California, Polyergus mexicanus is the most widely distributed Polyergus, but recent evidence has identified substantial genetic polymorphism within this species, including genetically divergent lineages associated with the use of different Formica host species. Given its unique behavior and genetic diversity, Polyergus mexicanus plays a critical role in maintaining ecosystem balance by influencing the population dynamics and genetic diversity of its host ant species, Formica, highlighting its conservation value and importance in the context of biodiversity preservation. Here, we present a high-quality genome assembly of P. mexicanus from a sample collected in Plumas County, CA, USA, in the foothills of the central Sierra Nevada. This genome assembly consists of 364 scaffolds spanning 252.31 Mb, with contig N50 of 481,250 kb, scaffold N50 of 10.36 Mb, and BUSCO completeness of 95.4%. We also assembled the genome of the Wolbachia endosymbiont of P. mexicanus - a single, circular contig spanning 1.23 Mb. These genome sequences provide essential resources for future studies of conservation genetics, population genetics, speciation, and behavioral ecology in this charismatic social insect.

Microscope Upcycling: Transforming legacy microscopes into automated cloud-integrated imaging systems

(2025)

Computerized microscopes improve repeatability, throughput, antisepsis, data analysis and data sharing in the biological laboratory, but these machines are cost-prohibitive in most academic environments. This is a barrier into collecting the large and consistent datasets required for machine learning analyses of microscopy data. We demonstrate hardware modifications and software to bring the features of modern computerized microscopes to decades-old legacy laboratory inverted microscopes. We demonstrate automation of X-Y positioning, focus stacking, image acquisition and image storage.

Cover page of Rapid synthesis of carbon-supported CoS2/CoSe2 heterostructures by magnetic induction heating for efficient hydrogen evolution reaction in acidic media

Rapid synthesis of carbon-supported CoS2/CoSe2 heterostructures by magnetic induction heating for efficient hydrogen evolution reaction in acidic media

(2025)

Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector

(2025)

Abstract: A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair $$(t\bar{t}H/A),$$ ( t t ¯ H / A ) , and with the H/A decaying into a $$t\bar{t}$$ t t ¯ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of $$139~\text {fb}^{-1}.$$ 139 fb - 1 . Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the $$t\bar{t}$$ t t ¯ +jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the $$t\bar{t}H/A \rightarrow t\bar{t}t\bar{t}$$ t t ¯ H / A → t t ¯ t t ¯ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 $$\text {GeV}$$ GeV and 1000 $$\text {GeV}$$ GeV , respectively. Assuming that both the H and A contribute to the $$t\bar{t}t\bar{t}$$ t t ¯ t t ¯ cross-section, $$\tan \beta $$ tan β values below 1.7 or 0.7 are excluded for a mass of 400 $$\text {GeV}$$ GeV or 1000 $$\text {GeV}$$ GeV , respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a $$t\bar{t}$$ t t ¯ pair.

Reconstruction and identification of pairs of collimated τ-leptons decaying hadronically using s=13 TeV pp collision data with the ATLAS detector

(2025)

Abstract: This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying $$\tau $$ τ -lepton pair with low transverse momentum. When two $$\tau $$ τ -leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for each of the $$\tau $$ τ -leptons. A dedicated treatment attempting to tag the $$\tau $$ τ -lepton pair as a single object is required. The reconstruction algorithm is based on a large radius jet and its associated two leading subjets, and the identification uses a boosted decision tree to discriminate between signatures from $$\tau ^+\tau ^-$$ τ + τ - systems and those arising from QCD jets. The efficiency of the identification algorithm is measured in $$Z\gamma $$ Z γ events using proton–proton collision data at $$\sqrt{s}=13$$ s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of $$139\,\text{ fb}^{-1}$$ 139 fb - 1 . The resulting data-to-simulation scale factors are close to unity with uncertainties ranging from 26 to 37%.