10 results on '"Condensed-matter physics"'
Search Results
2. Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke
- Author
-
Srinivasan, Vivek J., Mandeville, Emiri T., Can, Anil, Blasi, Francesco, Climov, Mihail, Daneshmand, Ali, Lee, Jeong Hyun, Yu, Esther, Radhakrishnan, Harsha, Lo, Eng H., Sakadžić, Sava, Eikermann-Haerter, Katharina, and Ayata, Cenk
- Subjects
Biology ,Biotechnology ,Bioengineering ,Biomedical Engineering ,Model Organisms ,Animal Models ,Mouse ,Neuroscience ,Cellular Neuroscience ,Neuronal Morphology ,Neuroimaging ,Engineering ,Signal Processing ,Medicine ,Cardiovascular ,Hemodynamics ,Stroke ,Neurology ,Cerebrovascular Diseases ,Ischemic Stroke ,Physics ,Condensed-Matter Physics ,Optics - Abstract
Progress in experimental stroke and translational medicine could be accelerated by high-resolution in vivo imaging of disease progression in the mouse cortex. Here, we introduce optical microscopic methods that monitor brain injury progression using intrinsic optical scattering properties of cortical tissue. A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described. In the acute stages, the spatiotemporal interplay between hemodynamics and cell viability, a key determinant of pathogenesis, was imaged. In acute stroke, microscopic biomarkers for eventual infarction, including capillary non-perfusion, cerebral blood flow deficiency, altered cellular scattering, and impaired autoregulation of cerebral blood flow, were quantified and correlated with histology. Additionally, longitudinal microscopy revealed remodeling and flow recovery after one week of chronic stroke. Intrinsic scattering properties serve as reporters of acute cellular and vascular injury and recovery in experimental stroke. Multi-parametric OCT represents a robust in vivo imaging platform to comprehensively investigate these properties.
- Published
- 2013
- Full Text
- View/download PDF
3. Tracking Single Cells in Live Animals Using a Photoconvertible Near-Infrared Cell Membrane Label
- Author
-
Carlson, Alicia L., Fujisaki, Joji, Wu, Juwell, Runnels, Judith M., Turcotte, Raphaël, Celso, Cristina Lo, Scadden, David T., Strom, Terry B., and Lin, Charles P.
- Subjects
Biology ,Biotechnology ,Bioengineering ,Biomedical Engineering ,Developmental Biology ,Stem Cells ,Hematopoietic Stem Cells ,Stem Cell Niche ,Immunology ,Immune Cells ,T Cells ,Model Organisms ,Animal Models ,Molecular Cell Biology ,Cellular Types ,Engineering ,Medicine ,Hematology ,Bone Marrow and Stem Cell Transplantation ,Physics ,Condensed-Matter Physics ,Optics - Abstract
We describe a novel photoconversion technique to track individual cells in vivo using a commercial lipophilic membrane dye, DiR. We show that DiR exhibits a permanent fluorescence emission shift (photoconversion) after light exposure and does not reacquire the original color over time. Ratiometric imaging can be used to distinguish photoconverted from non-converted cells with high sensitivity. Combining the use of this photoconvertible dye with intravital microscopy, we tracked the division of individual hematopoietic stem/progenitor cells within the calvarium bone marrow of live mice. We also studied the peripheral differentiation of individual T cells by tracking the gain or loss of FoxP3-GFP expression, a marker of the immune suppressive function of CD4+ T cells. With the near-infrared photoconvertible membrane dye, the entire visible spectral range is available for simultaneous use with other fluorescent proteins to monitor gene expression or to trace cell lineage commitment in vivo with high spatial and temporal resolution.
- Published
- 2013
- Full Text
- View/download PDF
4. Molecular Threading: Mechanical Extraction, Stretching and Placement of DNA Molecules from a Liquid-Air Interface
- Author
-
Payne, Andrew C., Andregg, Michael, Kemmish, Kent, Hamalainen, Mark, Bowell, Charlotte, Bleloch, Andrew, Klejwa, Nathan, Lehrach, Wolfgang, Schatz, Ken, Stark, Heather, Marblestone, Adam, Church, George, Own, Christopher S., and Andregg, William
- Subjects
Engineering ,Bioengineering ,Mechanical Engineering ,Nanoengineering ,Robotics ,Materials Science ,Biomaterials ,Microtechnology ,Nanotechnology ,Bionanotechnology ,Nanorobotics ,Physics ,Condensed-Matter Physics ,Condensed Matter ,Condensed Matter Fluids - Abstract
We present “molecular threading”, a surface independent tip-based method for stretching and depositing single and double-stranded DNA molecules. DNA is stretched into air at a liquid-air interface, and can be subsequently deposited onto a dry substrate isolated from solution. The design of an apparatus used for molecular threading is presented, and fluorescence and electron microscopies are used to characterize the angular distribution, straightness, and reproducibility of stretched DNA deposited in arrays onto elastomeric surfaces and thin membranes. Molecular threading demonstrates high straightness and uniformity over length scales from nanometers to micrometers, and represents an alternative to existing DNA deposition and linearization methods. These results point towards scalable and high-throughput precision manipulation of single-molecule polymers.
- Published
- 2013
- Full Text
- View/download PDF
5. Local Thermometry of Neutral Modes on the Quantum Hall Edge
- Author
-
Venkatachalam, Vivek, Hart, Sean, Pfeiffer, Loren, West, Ken, and Yacoby, Amir
- Subjects
Condensed-matter physics - Abstract
Electrons in two dimensions and strong magnetic fields can form an insulating two-dimensional system with conducting one-dimensional channels along the edge. Electron interactions in these edges can lead to independent transport of charge and heat, even in opposite directions. Here, we heat the outer edge of such a quantum Hall system using a quantum point contact. By placing quantum dots upstream and downstream from the heater, we measure both the chemical potential and temperature of that edge to study charge and heat transport, respectively. We find that charge is transported exclusively downstream, but heat can be transported upstream when the edge has additional structure related to fractional quantum Hall (FQH) physics. Surprisingly, this can occur even when the bulk is in an integer quantum Hall state and the edge contains no signatures of FQH charge transport. We also find an unexpected bulk contribution to heat transport at ν = 1., Physics
- Published
- 2012
- Full Text
- View/download PDF
6. Raman Spectroscopy Provides a Powerful Diagnostic Tool for Accurate Determination of Albumin Glycation
- Author
-
Dingari, Narahara Chari, Kang, Jeon Woong, Dasari, Ramachandra R., Barman, Ishan, and Horowitz, Gary Leigh
- Subjects
Biology ,Biochemistry ,Biotechnology ,Bioengineering ,Chemistry ,Analytical Chemistry ,Medicine ,Diagnostic Medicine ,Pathology ,General Pathology ,Endocrinology ,Diabetic Endocrinology ,Physics ,Condensed-Matter Physics - Abstract
We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.
- Published
- 2012
- Full Text
- View/download PDF
7. Algebraic Charge Liquids
- Author
-
Kaul, Ribhu, Kim, Yong, Senthil, T., and Sachdev, Subir
- Subjects
condensed-matter physics ,materials physics ,strongly correlated electrons ,superconductivity - Abstract
High temperature superconductivity emerges in the cuprate compounds upon changing the electron density of an insulator in which the electron spins are antiferromagnetically ordered. A key characteristic of the superconductor is that electrons can be extracted from them at zero energy only if their momenta take one of four specific values (the 'nodal points'). A central enigma has been the evolution of the zero energy electrons in the metallic state between the antiferromagnet and the superconductor, and recent experiments yield apparently contradictory results. The oscillation of the resistance in this metal as a function of magnetic field indicate that the zero energy electrons carry momenta which lie on elliptical 'Fermi pockets', while ejection of electrons by high intensity light indicates that the zero energy electrons have momenta only along arc-like regions. We present a theory of new states of matter, which we call 'algebraic charge liquids', which arise naturally between the antiferromagnet and the superconductor, and reconcile these observations. Our theory also explains a puzzling dependence of the density of superconducting electrons on the total electron density, and makes a number of unique predictions for future experiments., Physics
- Published
- 2008
- Full Text
- View/download PDF
8. Quantum Magnetism and Criticality
- Author
-
Sachdev, Subir
- Subjects
condensed-matter physics ,quantum physics ,statistical physics ,thermodynamics and nonlinear dynamics - Abstract
Magnetic insulators have proved to be fertile ground for studying new types of quantum many body states, and I survey recent experimental and theoretical examples. The insights and methods transfer also to novel superconducting and metallic states. Of particular interest are critical quantum states, sometimes found at quantum phase transitions, which have gapless excitations with no particle- or wave-like interpretation, and control a significant portion of the finite temperature phase diagram. Remarkably, their theory is connected to holographic descriptions of Hawking radiation from black holes., Physics
- Published
- 2008
- Full Text
- View/download PDF
9. Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor
- Author
-
Luan, Lan, Liang, Ruixing, Koshnick, Nicholas C., Hardy, Walter N., Hoffman, Jennifer, Zeldov, Eli, Bonn, Douglas A., Straver, Eric W. J., Auslaender, Ophir M., and Moler, Kathryn A.
- Subjects
condensed-matter physics - Abstract
Superconductors often contain quantized microscopic whirlpools of electrons, called vortices, that can be modelled as one-dimensional elastic objects1. Vortices are a diverse area of study for condensed matter because of the interplay between thermal fluctuations, vortex–vortex interactions and the interaction of the vortex core with the three-dimensional disorder landscape. Although vortex matter has been studied extensively, the static and dynamic properties of an individual vortex have not. Here, we use magnetic force microscopy (MFM) to image and manipulate individual vortices in a detwinned YBa2Cu3O6.991 single crystal, directly measuring the interaction of a moving vortex with the local disorder potential. We find an unexpected and marked enhancement of the response of a vortex to pulling when we wiggle it transversely. In addition, we find enhanced vortex pinning anisotropy that suggests clustering of oxygen vacancies in our sample and demonstrates the power of MFM to probe vortex structure and microscopic defects that cause pinning., Physics
- Published
- 2009
- Full Text
- View/download PDF
10. Charge Fractionalization in Quantum Wires
- Author
-
Barak, Gilad, Halperin, Bertrand, Steinberg, Hadar, Yacoby, Amir, Pfeiffer, Loren N., West, Ken W., and Le Hur, Karyn
- Subjects
electronics ,photonics and device physics ,condensed-matter physics ,nanotechnology - Abstract
Although the unit of charge in nature is a fundamental constant, the charge of individual quasiparticles in some low-dimensional systems may be fractionalized. Quantum one-dimensional (1D) systems, for instance, are theoretically predicted to carry charge in units smaller than the electron charge e. Unlike 2D systems, the charge of these excitations is not quantized and depends directly on the strength of the Coulomb interactions. For example, in a 1D system with momentum conservation, it is predicted that the charge of a unidirectional electron that is injected into the wire decomposes into right- and left-moving charge excitations carrying fractional charges f0e and (1-f0)e respectively. f0 approaches unity for non-interacting electrons and is less than one for repulsive interactions. Here, we provide the first experimental evidence for charge fractionalization in one dimension. Unidirectional electrons are injected at the bulk of a wire and the imbalance in the currents detected at two drains on opposite sides of the injection region is used to determine f0. Our results elucidate further the collective nature of electrons in one dimension., Physics
- Published
- 2008
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.