California Institute of Technology

Electronic Properties Associated with Donor Impurities in Multivalley Semiconductors

In this thesis we treat the theory of the electronic properties of excitons bound to a neutral donor in multivalley semiconductors. The materials considered here are Si, Ge and GaP. To deal with the effect of realistic band structures on the excitons bound to a neutral donor, we...

Little Red Dots host Black Hole Stars: A unified family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy

Abstract We construct and characterise a sample of 146 little red dots (LRDs) across 2.0 < z < 9.3, selecting all sources with v-shaped UV-optical continua from JWST NIRSpec/PRISM spectra and compact morphologies in NIRCam/F444W imaging. We show that LRD continuum spectra are wel...

Morphogenesis of bacterial colonies in liquid crystalline environments

Natural bacterial habitats are often complex fluids with viscoelastic and anisotropic responses to stress; for example, they can take the form of liquid crystals (LCs), with elongated microscopic constituents that collectively align while still retaining the ability to flow. Howe...

The history of enzyme evolution embedded in metabolism.

Whereas phylogenetic reconstructions are a primary record of protein evolution, it is unknown whether the deep history of enzymes is encoded at higher levels of biological organization. Here, we demonstrate that the emergence and reuse history of enzymatic folds is embedded withi...

Neural dynamics underlying minute-timescale persistent behaviour in the human brain

Pursuing longer-term goals relies on representations of task context that can be maintained over long periods of time and switched flexibly when goals change. Little is known about the neural substrate for maintaining context representations on the minute-timescale on which human...

Resilient but Unreliable: Cross-Generational Restructuring of the Tribolium castaneum Gut Microbiome Under Contrasting Nutritional Regimes

Microbial communities are frequently exposed to environmental disturbances, yet recovery does not always lead to a single, predictable outcome. Distinguishing resilience, the capacity to recover following perturbation, from reliability, the predictability of that recovery, is ess...

Cooperative and collective quantum light emission from perovskite superball superstructures

Superfluorescence (SF), the coherent light burst from synchronized quantum emitters, has been demonstrated in perovskite quantum dot superlattices. However, limited control over self-assembly, heterogeneity and emitter properties has hindered systematic exploration of cooperative...

Clinician–Artificial Intelligence Collaboration for Mediterranean Meal-Plan Generation: Development, Technical Feasibility, and Professional Acceptability of the MAI-DIET Framework

Background/Objectives: Adherence to the Mediterranean diet has declined in recent decades, highlighting the need for practical, technology-enabled tools to support its adoption. This study developed and evaluated MAI-DIET, a clinician-supervised, data-driven, AI-assisted programm...

GRB 260310A / SN 2026fgk: A Multi-Wavelength Study of a Nearby Underluminous Long GRB and SN with a Complex Afterglow

Abstract We present a comprehensive multi-wavelength study of GRB 260310A / SN 2026fgk, a nearby (z = 0.153), long-duration gamma-ray burst (GRB) with an exceptionally underluminous prompt γ-ray emission and a Comptonized spectrum. The burst occurred at the edge of a blue host ga...

A Chronopotentiometric Study of the Participation of Various Ligands in the Oxidation of Chromium (II)

No abstract.

Stochastic tensor contraction for quantum chemistry

Many computational methods in ab initio quantum chemistry are formulated in terms of high-order tensor contractions, whose cost determines the size of system that can be studied. We introduce stochastic tensor contraction to perform such operations with greatly reduced cost, and...

The Binding of Methyl Mercury and DNA

A method for the quantitative measurement of methyl mercury (CH3Hg+) was developed in addition to a method for the quantitative study of the binding of CH3Hg+ to DNA. Preliminary results seem to indicate that CH3Hg+ binds to DNA; [CH3Hg+]/[DNA] bound reaches a maximum as [CH3Hg+]...

One sum to rule them all: a second order master rate sum rule for charm decays

A bstract We show that within the Standard Model any system of hadronic weak charm decays related by U -spin satisfies the following rate sum rule: $$ \frac{\left(\mathrm{sum}\ \mathrm{of}\ \mathrm{CF}\ \mathrm{and}\ \mathrm{DCS}\ \mathrm{CKM}-\mathrm{free}\ \mathrm{rates}\right)...

VPC Analysis of Pyrolysis Products of Saccharides

The pyrolysis products formed from the decomposition on a hot platinum coil of a number of saccharides were analyzed with a high-sensitivity vapor-phase chromatograph. Reproducibility was erratic, but the chromatographs of the pyrolysis products of mannose, dextrose, galactose, x...

Investigation of Cupric Chloride in Acetonitrile

No abstract.

Near-total loss of buttressing stresses observed on Pine Island Ice Shelf, West Antarctica

Ice shelves, the floating extensions of the Antarctic Ice Sheet, provide critical buttressing stresses that resist the seaward flow of ice and help set the position of the grounding line, where the ice goes afloat. As buttressing stresses are diminished by thinning or fracturing...

Non-ideal MHD and protostellar feedback effects on disk formation and evolution in numerical simulations of star cluster formation

Abstract While recent surveys have resolved hundreds of nearby protostellar disks, numerical simulations assuming ideal magnetohydrodynamics (MHD) have historically struggled to achieve disk formation due to efficient angular momentum removal by magnetic torques. Non-ideal MHD ef...

The Properties of Ribonuclease: a Study in Binding and Kinetics

The interaction between pancreatic ribonuclease and calf thymus DNA is studied as a function of kinetics and binding. It is found that native and denatured DNA bind strongly to RNase, and that the ratio. Kden/Knat = 5.7. It is also shown that at approximately equal concentrations...

The Interaction of the Silicotungstate Anion with Nucleic Acids and Preparation of Closed Circular DNA from HeLa Cell Mitochondria

This report describes an investigation of the interaction of the silicotungstate anion with DNA in acidic solutions. The properties of equilibrium density gradients of solutions of sodium silicotungstate were determined. It was found that the silicotungstate anion binds to proton...

The Photolysis of Diethyl, 3, 6-Dimethyl-2, 7-Octadienedioate

The title compound (4) was prepared and photolyzed to give 1, 4 Dimethyl-endo-5, exo-6-dicarboethoxy [2, 1, 1] bicyclohexane (5) exclusively. Compound 5 was characterized by its spectra and the spectra of some of its derivativer.