796 results match your criteria: "City College of the City University of New York[Affiliation]"

Kondo Breakdown and Quantum Oscillations in SmB_{6}.

Phys Rev Lett

January 2016

Center for Materials Theory, Rutgers University, Piscataway, New Jersey, 08854, USA.

Recent quantum oscillation experiments on SmB_{6} pose a paradox, for while the angular dependence of the oscillation frequencies suggest a 3D bulk Fermi surface, SmB_{6} remains robustly insulating to very high magnetic fields. Moreover, a sudden low temperature upturn in the amplitude of the oscillations raises the possibility of quantum criticality. Here we discuss recently proposed mechanisms for this effect, contrasting bulk and surface scenarios.

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Protocol dependence of the jamming transition.

Phys Rev E

January 2016

Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA.

We propose a theoretical framework for predicting the protocol dependence of the jamming transition for frictionless spherical particles that interact via repulsive contact forces. We study isostatic jammed disk packings obtained via two protocols: isotropic compression and simple shear. We show that for frictionless systems, all jammed packings can be obtained via either protocol.

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In this Letter we study the effect of time-reversal symmetric impurities on the Josephson supercurrent through two-dimensional helical metals such as on a topological insulator surface state. We show that, contrary to the usual superconducting-normal metal-superconducting junctions, the suppression of the supercurrent in the superconducting-helical metal-superconducting junction is mainly due to fluctuations of impurities in the junctions. Our results, which are a condensed matter realization of a part of the Mikheyev-Smirnov-Wolfenstein effect for neutrinos, show that the relationship between normal state conductance and the critical current of Josephson junctions is significantly modified for Josephson junctions on the surface of topological insulators.

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An important strategy for promoting voluntary movements after motor system injury is to harness activity-dependent corticospinal tract (CST) plasticity. We combine forelimb motor cortex (M1) activation with co-activation of its cervical spinal targets in rats to promote CST sprouting and skilled limb movement after pyramidal tract lesion (PTX). We used a two-step experimental design in which we first established the optimal combined stimulation protocol in intact rats and then used the optimal protocol in injured animals to promote CST repair and motor recovery.

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The New York Head-A precise standardized volume conductor model for EEG source localization and tES targeting.

Neuroimage

October 2016

Laboratory for Intelligent Imaging and Neural Computing, Columbia University, New York, NY 10027, USA; Machine Learning Department, Technische Universität Berlin, 10587, Berlin, Germany. Electronic address:

In source localization of electroencephalograpic (EEG) signals, as well as in targeted transcranial electric current stimulation (tES), a volume conductor model is required to describe the flow of electric currents in the head. Boundary element models (BEM) can be readily computed to represent major tissue compartments, but cannot encode detailed anatomical information within compartments. Finite element models (FEM) can capture more tissue types and intricate anatomical structures, but with the higher precision also comes the need for semi-automated segmentation, and a higher computational cost.

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Investigation of intramembranal protease catalysis demands the generation of intact biomembrane assemblies with structural integrity and lateral mobility. Here, we report the development of a microsphere supported-biomembrane platform enabling characterization of γ-secretase and substrate within proteolipobead assemblies via microscopy and flow cytometry. The active enzyme loading levels were tracked using an activity-based probe, with the biomembranes delineated by carbocyanine lipid reporters.

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Sepsis is a systemic inflammatory syndrome induced by bacterial infection that can lead to multiorgan failure. Endothelial surface glycocalyx (ESG) decorating the inner wall of blood vessels is a regulator of multiple vascular functions. Here, we tested a hypothesis that patchy degradation of ESG occurs early in sepsis and is a result of exocytosis of lysosome-related organelles.

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Learning and memory performance in breast cancer survivors 2 to 6 years post-treatment: the role of encoding versus forgetting.

J Cancer Surviv

June 2016

Neurocognitive Research Laboratory, Department of Psychiatry and Behavioral Sciences, Memorial Sloan Kettering Cancer Center, 641 Lexington Avenue, 7th Floor, New York, NY, 10022, USA.

Purpose: Our previous retrospective analysis of clinically referred breast cancer survivors' performance on learning and memory measures found a primary weakness in initial encoding of information into working memory with intact retention and recall of this same information at a delay. This suggests that survivors may misinterpret cognitive lapses as being due to forgetting when, in actuality, they were not able to properly encode this information at the time of initial exposure. Our objective in this study was to replicate and extend this pattern of performance to a research sample to increase the generalizability of this finding in a sample in which subjects were not clinically referred for cognitive issues.

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Tumor cell extravasation through the endothelial barrier forming the microvessel wall is a crucial step during tumor metastasis. However, where, how and how fast tumor cells transmigrate through endothelial barriers remain unclear. Using an in vitro transwell model, we performed a transmigration assay of malignant breast tumor cells (MDA-MB-231) through brain and lung microvascular endothelial monolayers under control and pathological conditions.

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Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as "chemical herder" is sprayed onto the water surrounding the spilled oil.

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We compute the photoemission intensity and polarization for the surface states in topological insulators. Due to the chirality and linear energy dispersion the effective electron-photon coupling is normalized by the tunneling amplitude (τ) into the vacuum. We investigate a chiral Dirac Hamiltonian for different cases: helical, Zeeman and warping, allowing us to study spin textures.

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Onset and cessation of motion in hydrodynamically sheared granular beds.

Phys Rev E Stat Nonlin Soft Matter Phys

October 2015

Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA.

We performed molecular dynamics simulations of granular beds driven by a model hydrodynamic shear flow to elucidate general grain-scale mechanisms that determine the onset and cessation of sediment transport. By varying the Shields number (the nondimensional shear stress at the top of the bed) and particle Reynolds number (the ratio of particle inertia to viscous damping), we explore how variations of the fluid flow rate, particle inertia, and fluid viscosity affect the onset and cessation of bed motion. For low to moderate particle Reynolds numbers, a critical boundary separates mobile and static states.

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Transmission in near-infrared optical windows for deep brain imaging.

J Biophotonics

January 2016

Institute for Ultrafast Spectroscopy and Lasers, Department of Physics, the City College of the City University of New York, 160 Convent Avenue, New York, NY 10031, USA.

Near-infrared (NIR) radiation has been employed using one- and two-photon excitation of fluorescence imaging at wavelengths 650-950 nm (optical window I) for deep brain imaging; however, longer wavelengths in NIR have been overlooked due to a lack of suitable NIR-low band gap semiconductor imaging detectors and/or femtosecond laser sources. This research introduces three new optical windows in NIR and demonstrates their potential for deep brain tissue imaging. The transmittances are measured in rat brain tissue in the second (II, 1,100-1,350 nm), third (III, 1,600-1,870 nm), and fourth (IV, centered at 2,200 nm) NIR optical tissue windows.

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N(6)-threonylcarbamoyl-adenosine (t6A) is one of the few RNA modifications that is universally present in life. This modification occurs at high frequency at position 37 of most tRNAs that decode ANN codons, and stabilizes cognate anticodon-codon interactions. Nearly all genetic studies of the t6A pathway have focused on single-celled organisms.

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Tumor cell adhesion to the microvessel wall is a critical step during tumor metastasis. Vascular endothelial growth factor (VEGF), a secretion of tumor cells, can increase microvessel permeability and tumor cell adhesion in the microvessel. To test the hypothesis that inhibiting permeability increase can reduce tumor cell adhesion, we used in vivo fluorescence microscopy to measure both microvessel permeability and adhesion rates of human mammary carcinoma MDA-MB-231 cells in post-capillary venules of rat mesentery under the treatment of VEGF and a cAMP analog, 8-bromo-cAMP, which can decrease microvessel permeability.

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Posttraumatic Malalignment of the Humeral Shaft: Challenging the Existing Paradigm.

J Orthop Trauma

February 2016

*NYU Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY;†Department of Orthopaedics, Jamaica Hospital Medical Center, Jamaica, NY; and‡Department of Biomedical Engineering, The City College of the City University of New York, New York, NY.

Objective: To investigate the impact of posttraumatic humeral shaft malalignment on the ability to position the hand in space.

Methods: Two unique models were created: a cadaveric model and a computerized 3-dimensional (3D) model. In the cadaveric model, a midshaft transverse osteotomy of the humerus was created to simulate fracture.

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Clinically Effective Treatment of Fibromyalgia Pain With High-Definition Transcranial Direct Current Stimulation: Phase II Open-Label Dose Optimization.

J Pain

January 2016

Laboratory of Neuromodulation, Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts. Electronic address:

Unlabelled: Despite promising preliminary results in treating fibromyalgia (FM) pain, no neuromodulation technique has been adopted in clinical practice because of limited efficacy, low response rate, or poor tolerability. This phase II open-label trial aims to define a methodology for a clinically effective treatment of pain in FM by establishing treatment protocols and screening procedures to maximize efficacy and response rate. High-definition transcranial direct current stimulation (HD-tDCS) provides targeted subthreshold brain stimulation, combining tolerability with specificity.

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Motor Cortex Activity Organizes the Developing Rubrospinal System.

J Neurosci

September 2015

Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, New York 10031

The corticospinal and rubrospinal systems function in skilled movement control. A key question is how do these systems develop the capacity to coordinate their motor functions and, in turn, if the red nucleus/rubrospinal tract (RN/RST) compensates for developmental corticospinal injury? We used the cat to investigate whether the developing rubrospinal system is shaped by activity-dependent interactions with the developing corticospinal system. We unilaterally inactivated M1 by muscimol microinfusion between postnatal weeks 5 and 7 to examine activity-dependent interactions and whether the RN/RST compensates for corticospinal tract (CST) developmental motor impairments and CST misprojections after M1 inactivation.

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Aquaporin-1 shifts the critical transmural pressure to compress the aortic intima and change transmural flow: theory and implications.

Am J Physiol Heart Circ Physiol

December 2015

Department of Chemical Engineering, City College of the City University of New York, New York; and Department of Medicine, College of Physicians and Surgeons, Columbia University, New York

Transmural-pressure (ΔP)-driven plasma advection carries macromolecules into the vessel wall, the earliest prelesion atherosclerotic event. The wall's hydraulic conductivity, LP, the water flux-to-ΔP ratio, is high at low pressures, rapidly decreases, and remains flat to high pressures (Baldwin AL, Wilson LM. Am J Physiol Heart Circ Physiol 264: H26-H32, 1993; Nguyen T, Toussaint, Xue JD, Raval Y, Cancel CB, Russell LM, Shou S, Sedes Y, Sun O, Yakobov Y, Tarbell JM, Jan KM, Rumschitzki DS.

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The expression of specific transcription factors determines the differentiated features of postmitotic neurons. However, the mechanism by which specific molecules determine neuronal cell fate and the extent to which the functions of transcription factors are conserved in evolution are not fully understood. In C.

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The interfacial adsorption of proteins in surfactant laden systems occurs both in nature and industrial processing, yet much of the fundamental behavior behind these systems is still not well understood. We report the development of a system that monitors optical transitions of a liquid-crystalline/aqueous interface to examine the dynamics of adsorption of two rationally designed model peptide molecules. The two molecules synthesized in this study were both designed to become surface-active upon folding and contain the same net charge of +3, but one of the peptides, K-2.

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Conservative phase-field lattice Boltzmann model for interface tracking equation.

Phys Rev E Stat Nonlin Soft Matter Phys

June 2015

Department of Mechanical Engineering, the City College of the City University of New York, New York, New York 10031, USA.

Based on the phase-field theory, we propose a conservative lattice Boltzmann method to track the interface between two different fluids. The presented model recovers the conservative phase-field equation and conserves mass locally and globally. Two entirely different approaches are used to calculate the gradient of the phase field, which is needed in computation of the normal to the interface.

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The "burnout syndrome" has been defined as a combination of emotional exhaustion, depersonalization, and reduced personal accomplishment caused by chronic occupational stress. Although there has been increasing medical interest in burnout over the last decades, it is argued in this paper that the syndrome cannot be elevated to the status of diagnostic category, based on (1) an analysis of the genesis of the burnout construct, (2) a review of the latest literature on burnout-depression overlap, (3) a questioning of the three-dimensional structure of the burnout syndrome, and (4) a critical examination of the notion that burnout is singularized by its job-related character. It turns out that the burnout construct is built on a fragile foundation, both from a clinical and a theoretical standpoint.

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Assessment of the correlation between aerosol optical depth (AOD) and particulate matter (PM) is critical to satellite remote sensing of air quality, e.g. ground PM10 and ground PM2.

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