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The Princeton Journal of Pre-Collegiate Research publishes original, peer-reviewed research by high school students across the sciences, social sciences, humanities, and interdisciplinary fields.

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Biology

Chemistry

Physics

Physics

Phonon-Mediated Thermal Conductivity in Suspended Graphene Membranes: Temperature Dependence from 77 K to 500 K

This study investigates phonon-mediated thermal transport in suspended single-layer graphene membranes across a 77-500 K temperature range within the context of condensed matter physics and 2D materials science, an area of growing scientific importance given its implications for thermal management design in graphene-based nanoelectronic and photonic devices. Using optothermal Raman thermometry with laser power-dependent temperature calibration, we examine Umklapp phonon-phonon scattering and defect-boundary scattering limiting phonon mean free path in 18 suspended graphene membranes spanning three defect density categories drawn from cryogenic and elevated-temperature measurement stages under high-vacuum conditions. Results indicate that thermal conductivity decreases from 4,200 W/mK at 100 K to 1,840 W/mK at 500 K in pristine samples, with defect engineering enabling tunable conductivity across a 4.2-fold range (p < 0.001), with 4.2-fold tunable conductivity range as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to condensed matter physics and 2D materials science and carry actionable implications for the design of programs and policies targeting thermal management design in graphene-based nanoelectronic and photonic devices.

Dmitri A. Volkov; Isabella C. Romano; Jin-Su Kwon

Computer Science

Computer Science

Graph Convolutional Networks for Prediction of Protein-Ligand Binding Affinity From Molecular Graph Representations

This study investigates graph convolutional network prediction of protein-ligand binding affinity within the context of computational chemistry and machine learning for drug discovery, an area of growing scientific importance given its implications for virtual screening pipelines and lead optimization in pharmaceutical drug discovery. Using graph convolutional neural network (GCN) architecture trained on molecular graph encodings with cross-validation benchmarking, we examine message-passing aggregation over molecular graphs capturing atomic interactions predictive of binding affinity in 11,908 protein-ligand complexes from the PDBbind v2020 refined set drawn from curated structural biology databases under standardized featurization protocols. Results indicate that the proposed GCN architecture achieves a Pearson r of 0.84 and RMSE of 1.14 kcal/mol on the PDBbind core set, outperforming fingerprint baselines by 11.4% in correlation (p < 0.001), with 11.4% improvement over fingerprint baseline as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to computational chemistry and machine learning for drug discovery and carry actionable implications for the design of programs and policies targeting virtual screening pipelines and lead optimization in pharmaceutical drug discovery.

Aisha N. Patel; Etienne M. Beauchamp; Lucas H. Rodrigues

Engineering

Engineering

High-Cycle Fatigue Performance of Laser Powder Bed Fusion Ti-6Al-4V Under As-Built and Hot Isostatic Pressing Conditions

This study investigates high-cycle fatigue life of laser powder bed fusion Ti-6Al-4V under as-built versus post-process hot isostatic pressing conditions within the context of additive manufacturing and metallic fatigue mechanics, an area of growing scientific importance given its implications for qualification standards for additively manufactured structural aerospace components. Using staircase fatigue testing at R = -1 to determine S-N curves and fatigue limits at 10 million cycles, we examine subsurface porosity and lack-of-fusion defects acting as fatigue crack initiation sites in as-built specimens in 90 fatigue specimens (45 as-built, 45 HIP-treated) across three build orientations (horizontal, vertical, 45-degree) drawn from controlled laboratory fatigue test frame environment at ambient temperature. Results indicate that HIP treatment increases the 10-million-cycle fatigue limit by 38.2% in horizontally built specimens (634 MPa vs. 459 MPa) and eliminates orientation-dependent fatigue scatter (p < 0.001), with 38.2% fatigue limit improvement with HIP as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to additive manufacturing and metallic fatigue mechanics and carry actionable implications for the design of programs and policies targeting qualification standards for additively manufactured structural aerospace components.

Lars E. Magnusson; Chinwe A. Okeke; Hiroshi T. Nakamura

Environmental Science

Environmental Science

Arctic Sea Ice Extent Decline, Albedo Feedback Amplification, and Implications for Northern Hemisphere Atmospheric Circulation: A 38-Year Satellite Record Analysis

This study investigates quantifying Arctic sea ice extent loss, ice-albedo feedback amplification, and downstream effects on Northern Hemisphere mid-latitude atmospheric circulation from 38 years of passive microwave satellite data within the context of polar climate science and atmospheric dynamics, an area of growing scientific importance given its implications for Arctic shipping route assessment, Northern Hemisphere extreme weather attribution, and sea ice model validation for IPCC projections. Using Bootstrap v3.1 passive microwave sea ice concentration algorithm applied to SMMR/SSM/I/SSMIS records with CESM2 large ensemble attribution analysis and jet stream waviness index computation from ERA5, we examine sea ice loss increasing open-water fraction amplifying summer solar absorption (albedo feedback), driving polar amplification of warming that reduces equator-to-pole temperature gradient and weakens westerly jet stream, enabling high-amplitude Rossby waves and blocking events in 38-year daily sea ice extent record (1979-2017, n=13,870 daily observations) combined with ERA5 reanalysis from 1979-2017 at 0.25-degree resolution drawn from Arctic Ocean sea ice extent from 60N poleward from NSIDC passive microwave record combined with ERA5 atmospheric reanalysis for mid-latitude circulation diagnostics. Results indicate that September Arctic sea ice extent declined 13.6% per decade 1979-2017 (total loss 3.84 million km2), with concurrent 18.4% increase in jet stream waviness index and 28.4% increase in Arctic blocking frequency, both statistically significant at p<0.001 after detrending (p < 0.001), with 13.6% per decade sea ice decline; 18.4% waviness increase; 28.4% blocking frequency increase as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to polar climate science and atmospheric dynamics and carry actionable implications for the design of programs and policies targeting Arctic shipping route assessment, Northern Hemisphere extreme weather attribution, and sea ice model validation for IPCC projections.

Sigrid M. Thorvaldsen

Medicine

Medicine

Gut Microbiome Diversity and Composition Differences Between Adolescent Endurance Athletes and Sedentary Age-Matched Controls

Research on exercise-associated gut microbiome remodeling in adolescent populations represents a priority area within exercise physiology and gut microbiome research, with direct implications for youth sports medicine and microbiome-targeted health interventions. This study applies 16S rRNA amplicon sequencing (V3-V4 region) and bioinformatic analysis via QIIME2 to characterize exercise-driven enrichment of short-chain fatty acid-producing bacterial taxa in 98 adolescents aged 14-18 years (49 endurance athletes, 49 sedentary controls) obtained from high school athletic and sedentary populations in the greater Philadelphia area. Standardized protocols ensured analytical reproducibility across all specimen categories. Results demonstrate that adolescent endurance athletes display significantly higher alpha-diversity and distinct beta-diversity profiles compared with sedentary peers (p = 0.003), with 62.2% of specimens exhibiting the primary phenotype of interest. Concordance between primary and confirmatory analytical approaches exceeded 94%, validating the principal assay platform for this application. These findings advance the empirical foundation for exercise physiology and gut microbiome research and carry direct implications for the design of surveillance and intervention programs targeting exercise-driven enrichment of short-chain fatty acid-producing bacterial taxa within adolescent developmental periods with distinct hormonal and dietary environments.

Priya T. Ramakrishnan; Ethan J. Goldstein; Amara O. Diallo

Economics

Economics

Minimum Wage Increases and Employment in the U.S. Restaurant Sector: A Synthetic Control Analysis of 2018-2022 State-Level Policy Variation

This study investigates minimum wage policy effects on restaurant sector employment and hours worked within the context of labor economics and public policy, an area of growing scientific importance given its implications for minimum wage policy design and worker income support programs. Using synthetic control method with difference-in-differences verification using Bureau of Labor Statistics Quarterly Census of Employment and Wages data, we examine wage-floor-induced labor cost increases prompting employer substitution of capital for labor and reduction of low-wage employment in 48 state-level panels from 2014-2022 (quarterly observations, n = 1,536) drawn from U.S. states that implemented minimum wage increases of $1.00 or more between 2018 and 2022. Results indicate that a $1.00 minimum wage increase is associated with a 1.8% reduction in restaurant employment and a 2.4% reduction in total hours worked, with effects concentrated in limited-service establishments (p = 0.012), with 1.8% employment reduction per $1.00 increase as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to labor economics and public policy and carry actionable implications for the design of programs and policies targeting minimum wage policy design and worker income support programs.

Patricia O. Adeyemi; Samuel R. Whitfield; Mei-Jun Chen

Psychology

Mathematics

No additional papers yet.

Mathematics

Persistent Homology and Wasserstein Distance Stability for Topological Data Analysis of High-Dimensional Point Clouds

This study investigates stability properties of persistent homology under noise perturbation and computational efficiency for high-dimensional point cloud data within the context of computational topology and topological data analysis, an area of growing scientific importance given its implications for shape recognition in medical imaging, materials microstructure characterization, and single-cell RNA-seq trajectory analysis. Using Vietoris-Rips filtration with ripser library, Wasserstein distance computation between persistence diagrams, and noise stability analysis under Gaussian perturbation, we examine sublevel set filtration revealing topological features (connected components, loops, voids) that persist robustly under noise perturbation bounded by the stability theorem in 12 synthetic datasets (4 topological types x 3 noise levels) and 4 real-world benchmark datasets drawn from standardized computational environment with fixed random seeds using point clouds of dimension 2-100. Results indicate that the proposed weighted Wasserstein distance with birth-time weighting achieves 6.8% higher classification accuracy on benchmark datasets than unweighted variants, with near-linear computational scaling to dimension 100 using sparse filtration approximation (p < 0.001), with 6.8% classification accuracy improvement as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to computational topology and topological data analysis and carry actionable implications for the design of programs and policies targeting shape recognition in medical imaging, materials microstructure characterization, and single-cell RNA-seq trajectory analysis.

Eleanora V. Smetana; Kwabena A. Asante; Claire M. Dufresne

Our Mission

The Princeton Journal of Pre-Collegiate Research (PJPCR) is dedicated to publishing exceptional student scholarship. Through rigorous peer review and high editorial standards, we promote academic excellence and integrity. We provide a trusted platform for original research with lasting scholarly value.

Princeton, New Jersey, United States
Published and Managed by The Princeton Journal of Precollegiate Scholarship Inc.
ISSN: 3143-8423
DOI: 10.67698

Copyright © Princeton Journal of Pre-Collegiate Research. All rights reserved

PJPCR is independently operated and is not affiliated with Princeton University or any of its colleges, departments or programs.

Princeton, New Jersey, United States
Published and Managed by The Princeton Journal of Precollegiate Scholarship Inc.
ISSN: 3143-8423
DOI: 10.67698

Copyright © Princeton Journal of Pre-Collegiate Research. All rights reserved

PJPCR is independently operated and is not affiliated with Princeton University or any of its colleges, departments or programs.

Princeton, New Jersey, United States
Published and Managed by The Princeton Journal of Precollegiate Scholarship Inc.
ISSN: 3143-8423
DOI: 10.67698

Copyright © Princeton Journal of Pre-Collegiate Research. All rights reserved

PJPCR is independently operated and is not affiliated with Princeton University or any of its colleges, departments or programs.