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Parvalbumin-expressing interneurons coordinate hippocampal network dynamics required for memory consolidation (vol 8, 15039, 2017)

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NATURE COMMUNICATIONS 2017年第1期8卷 1-14页

作者： Ognjanovski, Nicolette Schaeffer, Samantha Wu, Jiaxing Mofakham, Sima Maruyama, Daniel Zochowski, Michal Aton, Sara J. Department of Molecular Cellular and Developmental Biology University of Michigan Ann Arbor Michigan 48109 USA. Applied Physics Program University of Michigan Ann Arbor Michigan 48109 USA. Biophysics Program University of Michigan Ann Arbor Michigan 48109 USA. Department of Physics University of Michigan Ann Arbor Michigan 48109 USA.

Activity in hippocampal area CA1 is essential for consolidating episodic memories, but it is unclear how CA1 activity patterns drive memory formation. We find that in the hours following single-trial contextual fear conditioning (CFC), fast-spiking interneurons (which typically express parvalbumin (PV)) show greater firing coherence with CA1 network oscillations. Post-CFC inhibition of PV+ interneurons blocks fear memory consolidation. This effect is associated with loss of two network changes associated with normal consolidation: (1) augmented sleep-associated delta (0.5-4 Hz), theta (4-12 Hz) and ripple (150-250 Hz) oscillations; and (2) stabilization of CA1 neurons' functional connectivity patterns. Rhythmic activation of PV+ interneurons increases CA1 network coherence and leads to a sustained increase in the strength and stability of functional connections between neurons. Our results suggest that immediately following learning, PV+ interneurons drive CA1 oscillations and reactivation of CA1 ensembles, which directly promotes network plasticity and long-term memory formation.

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Protein Folding as a Jamming Transition

PRX Life

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PRX Life 2025年第1期3卷 013018-013018页

作者： Alex T. Grigas Zhuoyi Liu Jack A. Logan Mark D. Shattuck Corey S. O'Hern Graduate Program in Computational Biology and Biomedical Informatics Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology Yale University New Haven Connecticut 06520 USA Department of Mechanical Engineering Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA

Proteins fold to a specific functional conformation with a densely packed core that controls their stability. Despite their importance, we lack a quantitative explanation for why all protein cores, regardless of their overall fold, possess the same average packing fraction 〈ϕ〉≈0.55. However, important developments in the physics of jamming in particulate systems can shed light on the packing of protein cores. Here, we extend the framework of jamming to describe core packing in collapsed polymers, as well as in all-atom models of folded proteins. First, we show in a spherical bead-spring polymer model (with and without bond-angle constraints) that as the hydrophobic interactions increase relative to thermal fluctuations, a jamming-like transition occurs when the core packing fraction exceeds ϕc with the same power-law scaling behavior for the potential energy Vr, excess contact number ΔN, and characteristic frequency of the vibrational density of states ω* versus Δϕ=ϕ−ϕc as that for jammed particulate systems. Then, we develop an all-atom model for proteins and find that, above ϕc∼0.55, protein cores undergo a jamming-like transition, but with anomalous power-law scaling for Vr, ΔN, and ω* versus Δϕ. The all-atom protein model remains close to the native protein structure during jamming and accurately refolds from partially unfolded states.

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Identifying Materials-Level Sources of Performance Variation in Superconducting Transmon Qubits

arXiv

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arXiv 2025年

作者： Murthy, Akshay A. Bal, Mustafa Bedzyk, Michael J. Cansizoglu, Hilal Chan, Randall K. Chandrasekhar, Venkat Crisa, Francesco Datta, Amlan Deng, Yanpei Matute Diaz, Celeo D. Dravid, Vinayak P. Garcia-Wetten, David A. Garattoni, Sabrina Ghimire, Sunil Goronzy, Dominic P. de Graaf, Sebastian E. Haeuser, Sam Hersam, Mark C. Isheim, Dieter Joshi, Kamal Kim, Richard Kolachina, Saagar Kopas, Cameron J. Kramer, Matthew J. Lachman, Ella O. Lee, Jaeyel Lim, Peter G. Lunin, Andrei Mah, William Marshall, Jayss Mutus, Josh Y. Oh, Jin-Su Pappas, David P. Park, Joong-Mok Prozorov, Ruslan dos Reis, Roberto Seidman, David N. Sung, Zuhawn Tanatar, Makariy Walker, Mitchell J. Wang, Jigang Wu, Haotian Zhou, Lin Zhu, Shaojiang Grassellino, Anna Romanenko, Alexander BataviaIL60510 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Rigetti Computing BerkeleyCA94710 United States Ames National Laboratory AmesIA50011 United States Department of Physics & Astronomy Iowa State University AmesIA50011 United States Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States The NUANCE Center Northwestern University EvanstonIL60208 United States International Institute of Nanotechnology Northwestern University EvanstonIL60208 United States National Physical Laboratory TeddingtonTW11 0LW United Kingdom Department of Chemistry Northwestern University EvanstonIL60208 United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL60208 United States Applied Physics Graduate Program Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Iowa State University AmesIA50011 United States

The Superconducting Materials and Systems (SQMS) Center, a DOE National Quantum Information Science Research Center, has conducted a comprehensive and coordinated study using superconducting transmon qubit chips with known performance metrics to identify the underlying materials-level sources of device-to-device performance variation. Following qubit coherence measurements, these qubits of varying base superconducting metals and substrates have been examined with various nondestructive and invasive material characterization techniques at Northwestern University, Ames National Laboratory, and Fermilab as part of a blind study. We find trends in variations of the depth of the etched substrate trench, the thickness of the surface oxide, and the geometry of the sidewall, which when combined, lead to correlations with the T1 lifetime across different devices. In addition, we provide a list of features that varied from device to device, for which the impact on performance requires further studies. Finally, we identify two low-temperature characterization techniques that may potentially serve as proxy tools for qubit measurements. These insights provide materials-oriented solutions to not only reduce performance variations across neighboring devices, but also to engineer and fabricate devices with optimal geometries to achieve performance metrics beyond the state-of-the-art values. © 2025, CC BY.

关键词： Qubits

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Precessional frequency tuning in Ni81Fe19/(Ni 81Fe19)1-xEux (50 nm) bilayers

Precessional frequency tuning in Ni81Fe19/(Ni 81Fe19)1-xEux ...

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作者： Cheng, Lili Song, Hajung Bailey, William E. Materials Science Program Department of Applied Physics Columbia University New York NY 10027 United States

We present a study of the precessional dynamics of exchange coupled Ni 81Fe19/Ni81Fe19:Eux, bilayers, 50 nm thick. Eu codopants are of interest in soft ferromagnetic films since they can be used to enhance the gigahertz precessional frequency (f p) in Ni81Fe19 thin films without contributing to damping. Under-damped precessional dynamics with fp 'tunable' by as much as roughly 0.3 GHz were observed. Dynamical behavior agrees well with a single-domain Landau-Lifshitz simulation at constant relaxation rate λ/4π = 150 MHz across the series. The variation of precessional frequency with bias field shows that the enhancement of resonant frequency arises from an increase of dynamic anisotropy HK, matched well by static HK as measured by SQUID. An increasing contribution in g factor (2.1-2.4) is mostly balanced by a decreasing saturation magnetization Ms.

关键词： Magnetic thin films

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Improving radiotherapy precision through MLC model optimization for a Monaco treatment planning system

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Radiation physics and Chemistry 2025年

作者： Son, Nguyen Khac Long, Ngo Hoang Tu, Ha Anh Lam, Bao Tai, Duong Thanh Tamam, Nissren Sulieman, Abdelmoneim Sandwall, Peter Chow, James C.L. Department of Radiation Oncology Lam Dong General Hospital 1 Pham Ngoc Thach Str Ward 6 Lam Dong Da Lat City670000 Viet Nam Elekta AB Stockholm Sweden Department of Medical Physics Faculty of Medicine Nguyen Tat Thanh University 298-300A Nguyen Tat Thanh Street Ward 13 District 4 Ho Chi Minh City Viet Nam Department of Radiological Sciences College of Applied Medical Sciences King Saud Bin Abdulaziz University for Health Sciences Saudi Arabia Department of Physics College of Science Princess Nourah Bint Abdulrahman University P.O Box 84428 Riyadh11671 Saudi Arabia Imaging Physics Section Research and Innovation Department King Faisal Specialist Hospital & Research Center Riyadh Saudi Arabia Department of Radiation Oncology OhioHealth Mansfield OH United States Department of Radiation Oncology University of Toronto TorontoONN5T 1P5 Canada Radiation Medicine Program Princess Margaret Cancer Centre University Health Network ONM5G 1X6 Canada

This study optimizes the Multileaf Collimator (MLC) model in the Monaco Treatment Planning System (TPS), seeking to enhance dose calculation accuracy in radiotherapy. The focus is on refining key parameters such as leaf transmission, leaf groove width, and leaf offset to improve the alignment between calculated and measured dose distributions. The optimization process was conducted at Lam Dong General Hospital using the Elekta MLCi2 system. Iterative adjustments were made to the MLC parameters by analyzing the dose profiles of various test fields, such as FOURL, 3ABUT, and 7SEGA configurations. These profiles were used to detect discrepancies between calculated and measured doses, guiding the adjustments. After each adjustment, gamma analysis was applied to assess whether the refinements improved the quality of dose distribution. The refined MLC model was further validated using complex fields like DMLC, HIMRT, and HDMLC, and applied to clinical treatment plans to evaluate its effectiveness in real-world scenarios. Significant improvements in dose conformity and precision were observed. For instance, optimization of leaf transmission reduced the difference between measured and calculated doses, improving from −2.238 cGy to 0.037 cGy. Adjustments to leaf groove width and leaf offset similarly enhanced dose accuracy. Validation results showed notable improvements in gamma pass rates, particularly for the stringent 1 %/1 mm criterion. The optimized model also demonstrated substantial improvements in gamma pass rates across various clinical scenarios, including rectum, prostate, esophageal, head-neck, breast, and lung cases. Optimization of the MLC model within the Monaco TPS has proven to be a valuable approach in enhancing dose calculation accuracy. The study highlights the importance of continuous quality assurance and fine-tuning of MLC parameters to maintain high standards of treatment accuracy, ultimately contributing to better clinical outcomes for patients. © 20

关键词： Radiotherapy

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Dynamics of one-dimensional spin models via complex-time evolution of tensor networks

arXiv

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arXiv 2025年

作者： Cha, Jeong Hyeok Lee, Hyun-Yong Kim, Heung-Sik Department of Semiconductor Physics Kangwon National University Chuncheon24341 Korea Republic of Interdisciplinary Program in Earth Environmental System Science and Engineering Kangwon National University Chuncheon24341 Korea Republic of Division of Semiconductor Physics Korea University Sejong30019 Korea Republic of Department of Applied Physics Graduate School Korea University Sejong30019 Korea Republic of Institute of Quantum Convergence Technology Kangwon National University Chuncheon24341 Korea Republic of

Studying the real-time dynamics of strongly correlated systems poses significant challenges, which have recently become more manageable thanks to advances in density matrix renormalization group (DMRG) and tensor network methods. A notable development in this area is the introduction of a complex-time evolution scheme for tensor network states, originally suggested for solving Anderson impurity model and designed to suppress the growth of entanglement under time evolution. In this study, we employ the complex-time evolution scheme to investigate the dynamics of one-dimensional spin systems, specifically the transverse-field Ising model (TFIM) and the XXZ model. Our analysis revisits the dynamic critical exponent z of the TFIM and explores the dynamical structure factor in both gapped and gapless states of the XXZ model. Importantly, the complex-time evolution reproduces the results of real-time evolution while mitigating the rapid growth of quantum entanglement typically associated with the latter. These results demonstrate that the combination of complex-time evolution and extrapolation provides a robust and efficient framework for studying the dynamics of complex quantum systems, enabling more comprehensive insights into their behavior. © 2025, CC BY.

关键词： Quantum entanglement

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Amplification of enzymatic and microbial fuel cells using organic electrochemical transistors

Device

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Device 2025年

作者： Saxena, Ravindra Zhang, Xu Cai, Rong Suggs, Olivia Bruggeman, Chase Hickey, David P. Ajo-Franklin, Caroline M. Verduzco, Rafael Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston 77005 TX United States Department of Biosciences Rice University Houston 77005 TX United States Department of Chemical Engineering and Materials Science Michigan State University East Lansing 48824 MI United States Department of Bioengineering Rice University Houston 77005 TX United States Department of Chemical and Biomolecular Engineering Rice University Houston 77005 TX United States Rice Advanced Materials Institute Rice University Houston 77005 TX United States

Organic electrochemical transistors (OECTs) are thin-film devices operated in aqueous and biological environments for sensing chemicals and biomolecules. However, most sensor configurations involve introducing the target biomolecule directly in the OECT device. This has drawbacks because it may not be possible to have an electrolyte compatible with the target biomolecule or an environment optimal for the OECT. Here, we demonstrate a general and modular approach to building electrochemical sensors by coupling OECTs electronically with either an enzymatic fuel cell (EFC) or microbial fuel cell (MFC). We demonstrate that this modular approach can amplify currents by three orders of magnitude and enhance the signal-to-noise ratio. We also show that the power generated by the fuel cell can help tune the sensor's response for different applications. This work demonstrates a simple and versatile approach for amplifying currents from MFCs and EFCs useful for the development of bioelectronic sensors. © 2025 The Authors

关键词： amplification biosensors DTI-3: Develop electro-active bacteria enzymatic fuel cells microbial fuel cells organic electrochemical transistors power

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Magnetocrystalline anisotropy enhancement via epitaxial growth of Ni/Co/Cu thin films on MgO (001) and (111) substrates

Magnetocrystalline anisotropy enhancement via epitaxial grow...

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2002 IEEE International Magnetics Conference-2002 IEEE INTERMAG

作者： Stoica, Vladimir Alexandru Lukaszew, Rosa Alejandra Cionca, Codrin Clarke, Roy Applied Physics Program University of Michigan 500 E University Ann Arbor MI 48109 United States Department of Physics and Astronomy University of Toledo Toledo OH United States

ISBN: (纸本)0780373650

The epitaxial growth of Ni/Co/Cu thin films on MgO (001) and (111) substrates was studied. The samples with larger Co thickness were found to had a more abundant relaxed-lattice content of Co, enhancing the magnetocrystalline anisotropy contribution. The uniaxial magnetic anisotropy in the thinner samples was reduced as the thickness increased.

关键词： Magnetic thin films

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Inducing coherent quantum dot interactions

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Physical Review B 2018年第8期97卷 081301(R)-081301(R)页

作者： Eric W. Martin Steven T. Cundiff Applied Physics Program Department of Physics University of Michigan Ann Arbor 48109-1040 MI United States

We measure many-body interactions in isolated quantum dot states using double-quantum multidimensional coherent spectroscopy. Few states are probed in a diffraction limited spot, which is enabled by a collinear scheme in which radiated four-wave-mixing signals are measured with phase resolution. Many-body interactions are enhanced by an additional prepulse tuned to the delocalized quasicontinuum states. We propose this as a method for controlling coupling between quantum states.

关键词： Excitons Quantum information with solid state qubits Double quantum dots III-V semiconductors Quantum dots Quantum wells Four-wave mixing Photoluminescence

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Nucleation-Initiated Solidification of Thin Si Films

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MRS Online Proceedings Library 2011年第1期979卷 1-6页

作者： S. Hazair P. C. van der Wilt Y. Deng U. J. Chung A. B. Limanov James S. Im Program of Materials Science Department of Applied Physics and Applied Mathematics Columbia University New York USA

Thin Si films on SiO2 that are completely melted by pulsed laser irradiation cool rapidly and eventually solidify via nucleation and growth of solids. It has been observed that a variety of solidified microstructures can be obtained, depending primarily (but not exclusively) on the degree of supercooling achieved prior to the onset of nucleation. This paper focuses on investigating one particular and unusual polycrystalline microstructure that consists of “flowerlike” grains, the interiors of which can be described as being made up of two distinct regions: (1) an extremely defective core region consisting of fine-grained material, and (2) an outer region consisting of relatively defect-free crystal “petals” that radiate outwards. After considering the microstructural details and experimental behavior of the microstructure, we have formulated a growth-based physical model to account for the formation of the microstructure. The model is found to be also capable of accounting for other complex and unusual microstructures obtained via nucleation and growth in the complete melting regime.

关键词： Si nucleation & growth thin film

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