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.

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.

Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. V. Two Giant Planets in Kepler-511 but Only One Ran Away

(2025)

Systems hosting multiple giant planets are important laboratories for understanding planetary formation and migration processes. We present a nearly decade-long Doppler spectroscopy campaign from the HIRES instrument on the Keck-I telescope to characterize the two transiting giant planets orbiting Kepler-511 on orbits of 27 days and 297 days. The radial velocity measurements yield precise masses for both planets: 0.10 0 − 0.039 + 0.036 (2.6σ) and 0.4 4 − 0.12 + 0.11 (4σ) Jupiter masses, respectively. We use these masses to infer their bulk metallicities (i.e., metal mass fraction 0.87 ± 0.03 and 0.22 ± 0.04, respectively). Strikingly, both planets contain approximately 25-30 Earth masses of heavy elements but have very different amounts of hydrogen and helium. Envelope mass loss cannot account for this difference due to the relatively large orbital distance and mass of the inner planet. We conclude that the outer planet underwent runaway gas accretion while the inner planet did not. This bifurcation in accretion histories is likely a result of the accretion of gas with very different metallicities by the two planets or the late formation of the inner planet from a merger of sub-Neptunes. Kepler-511 uniquely demonstrates how giant planet formation can produce dramatically different outcomes even for planets in the same system.

Measurement of the Lund jet plane in hadronic decays of top quarks and W bosons with the ATLAS detector

(2025)

Abstract: The Lund jet plane (LJP) is measured for the first time in $$t\bar{t}$$ t t ¯ events, using 140 $$\textrm{fb}^{-1}$$ fb - 1 of $$\sqrt{s} = 13$$ s = 13 TeV pp collision data collected with the ATLAS detector at the LHC. The LJP is a two-dimensional observable of the sub-structure of hadronic jets that acts as a proxy for the kinematics of parton showers and hadron formation. The observable is constructed from charged particles and is measured for $$R=1.0$$ R = 1.0 anti- $$k_t$$ k t jets with transverse momentum above 350 GeV containing the full decay products of either a top quark or a daughter W boson. The other top quark in the event is identified from its decay into a b-quark, an electron or a muon and a neutrino. The measurement is corrected for detector effects and compared with a range of Monte Carlo predictions sensitive to different aspects of the hadronic decays of the heavy particles. In the W-boson-initiated jets, all the predictions are incompatible with the measurement. In the top quark initiated jets, disagreement with all predictions is observed in smaller subregions of the plane, and with a subset of the predictions across the fiducial plane. The measurement could be used to improve the tuning of Monte Carlo generators, for better modelling of hadronic decays of heavy quarks and bosons, or to improve the performance of jet taggers.

Observation of tt¯ Production in Pb+Pb Collisions at sNN=5.02 TeV with the ATLAS Detector

(2025)

Top-quark pair production is observed in lead–lead (Pb+Pb) collisions at sNN=5.02 TeV at the Large Hadron Collider with the ATLAS detector. The data sample was recorded in 2015 and 2018, amounting to an integrated luminosity of 1.9 nb−1. Events with exactly one electron and one muon and at least two jets are selected. Top-quark pair production is measured with an observed (expected) significance of 5.0 (4.1) standard deviations. The measured top-quark pair production cross section is σtt¯=3.6 −0.9+1.0(stat) −0.5+0.8(syst) μb, with a total relative uncertainty of 31%, and is consistent with theoretical predictions using a range of different nuclear parton distribution functions. The observation of this process consolidates the evidence of the existence of all quark flavors in the preequilibrium stage of the quark-gluon plasma at very high energy densities, similar to the conditions present in the early Universe. © 2025 CERN, for the ATLAS Collaboration 2025 CERN

Resource partitioning among pelagic predators remains stable despite annual variability in diet composition

(2025)

Diet data are critical for describing predator resource use and partitioning among competitors. However, time series needed to properly assess variability in resource use and partitioning are limited, especially in pelagic (open ocean) ecosystems where predators and prey make broad use of horizontal and vertical habitats. We examined a diet time series spanning two decades (1998-2018) consisting of 2749 stomachs from 10 pelagic predators in the southern California Current Ecosystem (SCCE): albacore tuna (Thunnus alalunga), Pacific bluefin tuna (Thunnus orientalis), swordfish (Xiphias gladius), blue shark (Prionace glauca), shortfin mako (Isurus oxyrinchus), common thresher shark (Alopias vulpinus), bigeye thresher shark (Alopias superciliosus), short-beaked common dolphin (Delphinus delphis), long-beaked common dolphin (Delphinus capensis) and northern right whale dolphin (Lissodelphis borealis). We quantified feeding habits with respect to prey taxonomy, length, vertical habitat and horizontal habitat. From 1998 to 2015, each predator exhibited diet variability but maintained consistent resource partitioning with the other predators. Across years, the diets of predators feeding mostly on shallow-living prey (<200 m) were more variable than those feeding on deeper-dwelling prey (>200 m). Following an increase in the abundance of northern anchovy (Engraulis mordax) in the SCCE starting in 2015, the ecological niches of Pacific bluefin tuna and swordfish converged. During 2016-2018, both predators fed more heavily on northern anchovy and other prey that occupy shallow nearshore habitats. We show that pelagic predators can maintain resource partitioning under a wide range of conditions. However, we also observe that drastic changes in resource availability can alter the degree of niche partitioning among competitors, providing new perspectives on the flexibility of predator niches. As climate change continues to alter food webs, understanding how predators forage will be essential for anticipating changes to pelagic ecosystem structure and services.

Amnesia & Memory: JEP and Allende

Delgado-P., Guillermo

(2025)

The author witnessed the Chilean coup d'etat in 1973. Years later he finds José Emilio Pacheco's, the Mexican bard, report on the event.

Spatial deep convolutional neural networks

(2025)

New lumped/distributed equivalent circuit based theory for avalanche breakdown suppressed reverse-bias PIN photodetectors

(2025)

A Pipeline and Recommendations for Population and Individual Diagnostic SNP Selection in Non-Model Species.

(2025)

Despite substantial reductions in the cost of sequencing over the last decade, genetic panels remain relevant due to their cost-effectiveness and flexibility across a variety of sample types. In particular, single nucleotide polymorphism (SNP) panels are increasingly favoured for conservation applications. SNP panels are often used because of their adaptability, effectiveness with low-quality samples, and cost-efficiency for population monitoring and forensics. However, the selection of diagnostic SNPs for population assignment and individual identification can be challenging. The consequences of poor SNP selection are under-powered panels, inaccurate results, and monetary loss. Here, we develop a novel and user-friendly SNP selection pipeline (mPCRselect) that can be used to select SNPs for population assignment and/or individual identification. mPCRselect allows any researcher, who has sufficient SNP-level data, to design a successful and cost-effective SNP panel for a diploid species of conservation concern.