20,033 results match your criteria: "California Institute Of Technology[Affiliation]"

Despite the sequencing revolution, large swaths of the genomes sequenced to date lack any information about the arrangement of transcription factor binding sites on regulatory DNA. Massively Parallel Reporter Assays (MPRAs) have the potential to dramatically accelerate our genomic annotations by making it possible to measure the gene expression levels driven by thousands of mutational variants of a regulatory region. However, the interpretation of such data often assumes that each base pair in a regulatory sequence contributes independently to gene expression.

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Utilizing Martian samples for future planetary exploration-Characterizing hazards and resources.

Proc Natl Acad Sci U S A

January 2025

Division of Space, Ecological, Arctic, and Resource-limited (SPEAR) Medicine, Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA 02114.

One of the most surprising and important findings of the first human landings on the Moon was the discovery of a very fine layer of lunar dust covering the entire surface of Moon along with the negative impacts of this dust on the well-being and operational effectiveness of the astronauts, their equipment, and instrumentation. The United States is now planning for human missions to Mars, a planet where dust can also be expected to be ubiquitous for many or most landing sites. For these missions, the design and operations of key hardware systems must take this dust into account, especially when related to crew health and safety.

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Mars Sample Return (MSR) has been the highest flagship mission priority in the last two Planetary Decadal Surveys of the National Academies of Science, Engineering, and Medicine (hereafter, "the National Academies") and was the highest priority flagship for Mars in the Decadal Survey that preceded them. This inspirational and challenging campaign, like the Apollo program's returned lunar samples, will potentially revolutionize our understanding of Mars and help inform how other planets are explored. MSR's technological advances will keep the NASA and European Space Agency at the forefront of planetary exploration, and data on returned samples will fill knowledge gaps for future human exploration.

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The NASA Mars 2020 Perseverance Rover Mission has collected samples of rock, regolith, and atmosphere within the Noachian-aged Jezero Crater, once the site of a delta-lake system with a high potential for habitability and biosignature preservation. Between sols 109 and 1,088 of the mission, 27 sample tubes have been sealed, including witness tubes. Each sealed sample tube has been collected along with detailed documentation provided by the Perseverance instrument payload, preserving geological and environmental context.

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Mars Sample Return: From collection to curation of samples from a habitable world.

Proc Natl Acad Sci U S A

January 2025

Science Group, Natural History Museum, London SW7 5BD, United Kingdom.

NASA's Mars 2020 mission has initiated collection of samples from Mars' Jezero Crater, which has a wide range of ancient rocks and rock types from lavas to lacustrine sedimentary rocks. The Mars Sample Return (MSR) Campaign, a joint effort between NASA and ESA, aims to bring the Perseverance collection back to Earth for intense scientific investigation. As the first return of samples from a habitable world, there are important challenges to overcome for the successful implementation of the MSR Campaign from the point of sample collection on Mars to the long-term curation of the samples on Earth.

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The organic carbon content of ancient rocks provides a fundamental record of the biosphere on early Earth. For over 50 y, the high organic content of Archean (>2.5 Ga) mudrocks has puzzled geologists and evolutionary biologists, because high biological primary productivity was unexpected for the nascent biosphere before the rise of O.

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Metabotropic GABA Receptor Activation Induced by G Protein Coupling.

J Am Chem Soc

January 2025

Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States.

G protein-coupled receptors (GPCRs) play central roles in regulating cellular responses through heterotrimeric G proteins (GP). Extensive studies have elucidated the complex cellular signaling mediated by GPCRs that accompany dynamic conformational changes upon activation. However, there has been less focus on the role of the GP on the activation process, particularly for class C GPCRs that function as obligate dimers.

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Ancient emergence of neuronal heterogeneity in the enteric nervous system of jawless vertebrates.

Dev Biol

January 2025

Division of Biology and Biological Engineering, California Institute of Technology, 91125, Pasadena, CA, USA. Electronic address:

While the enteric nervous system (ENS) of jawed vertebrates is largely derived from the vagal neural crest, lamprey are jawless vertebrates that lack the vagal neural crest, yet possess enteric neurons derived from late-migrating Schwann cell precursors. To illuminate homologies between the ENS of jawed and jawless vertebrates, here we examine the diversity and distribution of neuronal subtypes within the intestine of the sea lamprey during late embryonic and ammocete stages. In addition to previously described 5-HT-immunoreactive serotonergic neurons, we identified NOS and VIP neurons, consistent with motor neuron identity.

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A New Global Mangrove Height Map with a 12 meter spatial resolution.

Sci Data

January 2025

ETH Zürich, Institut für Umweltingenieurwissenschaften, Zürich, Switzerland.

Mangrove forests thrive along global tropical coasts, acting as a barrier that protects coastlines against storm surges and as nurseries for an entire food web. They are also known for their high carbon sequestration rates and soil carbon stocks. We introduce a new global mangrove canopy height map generated from TanDEM-X spaceborne elevation measurements collected during the 2011-2013 period with a 12-meter spatial resolution and an accuracy of 2.

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GLiDe: a web-based genome-scale CRISPRi sgRNA design tool for prokaryotes.

BMC Bioinformatics

January 2025

MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China.

Background: CRISPRi screening has become a powerful approach for functional genomic research. However, the off-target effects resulting from the mismatch tolerance between sgRNAs and their intended targets is a primary concern in CRISPRi applications.

Results: We introduce Guide Library Designer (GLiDe), a web-based tool specifically created for the genome-scale design of sgRNA libraries tailored for CRISPRi screening in prokaryotic organisms.

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In view of the high propensity of tertiary alkyl amines to be bioactive, the development of new methods for their synthesis is an important challenge. Transition-metal catalysis has the potential to greatly expand the scope of nucleophilic substitution reactions of alkyl electrophiles; unfortunately, in the case of alkyl amines as nucleophiles, only one success has been described so far: the selective mono-alkylation of primary amines to form secondary amines. Here, using photoinduced copper catalysis, we report the synthesis of tertiary alkyl amines from secondary amines and unactivated alkyl electrophiles, two readily available coupling partners.

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Rapid growth in bio-logging-the use of animal-borne electronic tags to document the movements, behaviour, physiology and environments of wildlife-offers opportunities to mitigate biodiversity threats and expand digital natural history archives. Here we present a vision to achieve such benefits by accounting for the heterogeneity inherent to bio-logging data and the concerns of those who collect and use them. First, we can enable data integration through standard vocabularies, transfer protocols and aggregation protocols, and drive their wide adoption.

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Curvature Dependence of Gravitational-Wave Tests of General Relativity.

Phys Rev Lett

December 2024

Center for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, New York, New York 10010, USA.

High-energy extensions to general relativity modify the Einstein-Hilbert action with higher-order curvature corrections and theory-specific coupling constants. The order of these corrections imprints a universal curvature dependence on observations while the coupling constant controls the deviation strength. In this Letter, we leverage the theory-independent expectation that modifications to the action of a given order in spacetime curvature (Riemann tensor and contractions) lead to observational deviations that scale with the system length scale to a corresponding power.

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Bootstrap Principle for the Spectrum and Scattering of Strings.

Phys Rev Lett

December 2024

Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, New York 10003, USA.

We show that the Veneziano amplitude of string theory is the unique solution to an analytically solvable bootstrap problem. Uniqueness follows from two assumptions: faster than power-law falloff in high-energy scattering and the existence of some infinite sequence in momentum transfer at which higher-spin exchanges cancel. The string amplitude-including the mass spectrum-is an output of this bootstrap.

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Article Synopsis
  • The study addresses the challenges of creating precise models for the nuclear force and managing uncertainties in quantum many-body calculations, which are crucial for understanding nuclei and nuclear matter.
  • Researchers use generative machine learning to develop new nucleon-nucleon interaction instances by training on existing potential data from literature.
  • The generative model successfully creates nucleon-nucleon potentials that yield high-quality scattering phase shifts, aiding in better estimation of theoretical uncertainties in nuclear calculations related to different nuclear interactions and resolution scales.
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The proteome is a terminal electron acceptor.

Proc Natl Acad Sci U S A

January 2025

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125.

Article Synopsis
  • Microbial metabolism is highly adaptable, allowing growth on varying carbon sources through fermentation and respiration.
  • A mathematical framework was developed to analyze cellular resource allocation alongside redox chemistry, highlighting how metabolism balances carbon, electrons, and energy while treating biomass as both a product and catalyst for growth.
  • The study found that proteins in microbes evolve to enhance redox matching, suggesting that genetic changes that may not benefit individual proteins can still be favored if they improve the overall fitness of the microbial population.
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Diversity in Notch ligand-receptor signaling interactions.

Elife

January 2025

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.

The Notch signaling pathway uses families of ligands and receptors to transmit signals to nearby cells. These components are expressed in diverse combinations in different cell types, interact in a many-to-many fashion, both within the same cell (in cis) and between cells (in trans), and their interactions are modulated by Fringe glycosyltransferases. A fundamental question is how the strength of Notch signaling depends on which pathway components are expressed, at what levels, and in which cells.

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Distinguishing whether a system supports alternate low-energy (locally stable) states-stable (true vacuum) versus metastable (false vacuum)-by direct observation can be difficult when the lifetime of the state is very long but otherwise unknown. Here we demonstrate, in a tractable model system, that there are physical phenomena on much shorter timescales that can diagnose the difference. Specifically, we study the time evolution of the magnetization following a quench in the tilted quantum Ising model, and show that its magnitude spectrum is an effective diagnostic.

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The coherent structure of the energy cascade in isotropic turbulence.

Sci Rep

January 2025

Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.

The energy cascade, i.e. the transfer of kinetic energy from large-scale to small-scale flow motions, has been the cornerstone of turbulence theories and models since the 1940s.

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The emergence of a local effective theory from a more fundamental theory of quantum gravity with seemingly fewer degrees of freedom is a major puzzle of theoretical physics. A recent approach to this problem is to consider general features of the Hilbert space maps relating these theories. In this work, we construct approximately local observables, or overlapping qubits, from such non-isometric maps.

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During memory formation, the hippocampus is presumed to represent the content of stimuli, but how it does so is unknown. Using computational modelling and human single-neuron recordings, we show that the more precisely hippocampal spiking variability tracks the composite features of each individual stimulus, the better those stimuli are later remembered. We propose that moment-to-moment spiking variability may provide a new window into how the hippocampus constructs memories from the building blocks of our sensory world.

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The iridium oxide (IrO) catalyst for the oxygen evolution reaction used industrially (in proton exchange membrane water electrolyzers) is scarce and costly. Although ruthenium oxide (RuO) is a promising alternative, its poor stability has hindered practical application. We used well-defined extended surface models to identify that RuO undergoes structure-dependent corrosion that causes Ru dissolution.

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Sensors are indispensable tools of modern life that are ubiquitously used in diverse settings ranging from smartphones and autonomous vehicles to the healthcare industry and space technology. By interfacing multiple sensors that collectively interact with the signal to be measured, one can go beyond the signal-to-noise ratios (SNR) attainable by the individual constituting elements. Such techniques have also been implemented in the quantum regime, where a linear increase in the SNR has been achieved via using entangled states.

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The benefits of sleep extend beyond the nervous system. Peripheral tissues impact sleep regulation, and increased sleep is observed in response to damaging conditions, even those that selectively affect non-neuronal cells. However, the 'sleep need' signal released by stressed tissues is not known.

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