Spontaneous photon emission by shaped quantum electron wavepackets and the QED origin of bunched electron beam superradiance.

It has been shown that the spontaneous emission rate of photons by free electrons, unlike stimulated emission, is independent of the shape or modulation of the quantum electron wavefunction (QEW). Nevertheless, here we show that the quantum state of the emitted photons is non-classical and does depend on the QEW shape. This non-classicality originates from the shape dependent off-diagonal terms of the photon density matrix.

Algorithm for solving a pump-probe model for an arbitrary number of energy levels.

We describe a generalized algorithm for evaluating the steady-state solution of the density matrix equation of motion, for the pump-probe scheme, when two fields oscillating at different frequencies couple the same set of atomic transitions involving an arbitrary number of energy levels, to an arbitrary order of the harmonics of the pump-probe frequency difference. We developed a numerical approach and a symbolic approach for this algorithm. We have verified that both approaches yield the same result for all cases studied, but require different computation time.

Towards a unified picture of polarization transfer - pulsed DNP and chemically equivalent PHIP.

Nuclear spin hyperpolarization techniques, such as dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP), have revolutionized nuclear magnetic resonance and magnetic resonance imaging. In these methods, a readily available source of high spin order, either electron spins in DNP or singlet states in hydrogen for PHIP, is brought into close proximity with nuclear spin targets, enabling efficient transfer of spin order under external quantum control. Despite vast disparities in energy scales and interaction mechanisms between electron spins in DNP and nuclear singlet states in PHIP, a pseudo-spin formalism allows us to establish an intriguing equivalence.

Meta-holograms under incoherent illumination: image properties and spackle pattern.

We study the properties of the images projected by meta-holograms under broadband incoherent/polychromatic illumination. We show that despite the broadband illumination, some of the coherent properties of the images such as the speckle pattern are retained even for sources with bandwidth of 20 nm. We study the projected images and their speckle pattern properties under various illumination spectra using a set of monochromatic images obtained at different wavelengths.

Single-pumped gain profile for a superluminal ring laser.

We present an approach for realizing a superluminal ring laser using a single isotope of atomic Rb vapor by producing electromagnetically induced transparency (EIT) in self-pumped Raman gain. Only a single pump laser is used for generating a Raman gain profile containing a dip at its center. The position and depth of this dip can be tuned by adjusting the intensity of the pump laser, allowing for optimizing the degree of enhancement in sensitivity within a certain operating range.

Solution-State 2D NMR Spectroscopy of Mixtures HyperpolarizedUsing Optically Polarized Crystals.

The HYPNOESYS method (Hyperpolarized NOE System), which relies on the dissolution of optically polarized crystals, has recently emerged as a promising approach to enhance the sensitivity of NMR spectroscopy in the solution state. However, HYPNOESYS is a single-shot method that is not generally compatible with multidimensional NMR. Here we show that 2D NMR spectra can be obtained from HYPNOESYS-polarized samples, using single-scan acquisition methods.

Translating evidence-based knowledge objects into practice.

This paper aims to show how organizational translation theories and models may supplement implementation science with a new process perspective on how knowledge objects such as Cochrane reviews, clinical guidelines and reference programs are implemented in practice in healthcare organizations. They build on Bruno Latour's idea about translation that states that the spread in time and space of anything-including knowledge objects-is in the hands of people and that each of these people may act in many different ways, letting the token drop, modifying it, deflecting it, betraying it, adding to it, or appropriating it. Implementation science theories, models and frameworks often try to identify general aspects of processes and variables that influence implementation processes.

Parahydrogen-Polarized [1- C]Pyruvate for Reliable and Fast Preclinical Metabolic Magnetic Resonance Imaging.

Hyperpolarization techniques increase nuclear spin polarization by more than four orders of magnitude, enabling metabolic MRI. Even though hyperpolarization has shown clear value in clinical studies, the complexity, cost and slowness of current equipment limits its widespread use. Here, a polarization procedure of [1- C]pyruvate based on parahydrogen-induced polarization by side-arm hydrogenation (PHIP-SAH) in an automated polarizer is demonstrated.

Demonstration of a superluminal laser using electromagnetically induced transparency in Raman gain.

We report the realization of a superluminal laser in which the dip in the gain profile necessary for anomalous dispersion is produced via electromagnetically induced transparency caused by the optical pumping laser. This laser also creates the ground state population inversion necessary for generating Raman gain. Compared to a conventional Raman laser with similar operating parameters but without the dip in the gain profile, the spectral sensitivity of this approach is explicitly demonstrated to be enhanced by a factor of ∼12.

Long-Lived, Transportable Reservoir of Nuclear Polarization Used to Strongly Enhance Solution-State NMR Signals.

There is a fundamental issue with the use of dynamic nuclear polarization (DNP) to enhance nuclear spin polarization: the same polarizing agent (PA) needed for DNP is also responsible for shortening the lifetime of the hyperpolarization. As a result, long-term storage and transport of hyperpolarized samples is severely restricted and the apparatus for DNP is necessarily located near or integrated with the apparatus using the hyperpolarized spins. In this paper, we demonstrate that naphthalene single crystals can serve as a long-lived reservoir of proton polarization that can be exploited to enhance signals in benchtop and high-field NMR of target molecules in solution at a site 300 km away by a factor of several thousand.

Parahydrogen-Polarized Fumarate for Preclinical Metabolic Magnetic Resonance Imaging.

We present a versatile method for the preparation of hyperpolarized [1-C]fumarate as a contrast agent for preclinical MRI, using parahydrogen-induced polarization (PHIP). To benchmark this process, we compared a prototype PHIP polarizer to a state-of-the-art dissolution dynamic nuclear polarization (d-DNP) system. We found comparable polarization, volume, and concentration levels of the prepared solutions, while the preparation effort is significantly lower for the PHIP process, which can provide a preclinical dose every 10 min, opposed to around 90 min for d-DNP systems.

High efficiency coupling to metal-insulator-metal plasmonic waveguides.

A periodic array of dual-Vivaldi antennas integrated with metal-insulator-metal (MIM) plasmonic waveguides was designed and investigated for its infrared light absorbance efficiency. Full-wave analysis was used to optimize MIM waveguides compatible with parallel and series connected DC leads without sacrificing radiation efficiency. Free-space to MIM waveguide in-coupling efficiency as high as 41% has been obtained in a sub-wavelength unit cell geometry at a wavelength of 1373 nm.

Extraordinary broadband impedance matching in highly dispersive media - the white light cavity approach.

Suppressing reflections from material boundaries has always been an objective, common to many disciplines, where wave phenomena play a role. While impedance difference between materials necessarily leads to a wave reflection, introducing matching elements can almost completely suppress this phenomenon. However, many impedance matching approaches are based on resonant conditions, which come at a price of narrow bandwidth operation.

Hyperpolarized Solution-State NMR Spectroscopy with Optically Polarized Crystals.

Nuclear spin hyperpolarization provides a promising route to overcome the challenges imposed by the limited sensitivity of nuclear magnetic resonance. Here we demonstrate that dissolution of spin-polarized pentacene-doped naphthalene crystals enables transfer of polarization to target molecules via intermolecular cross-relaxation at room temperature and moderate magnetic fields (1.45 T).

Neural networks enabled forward and inverse design of reconfigurable metasurfaces.

Nanophotonics has joined the application areas of deep neural networks (DNNs) in recent years. Various network architectures and learning approaches have been employed to design and simulate nanophotonic structures and devices. Design and simulation of reconfigurable metasurfaces is another promising application area for neural network enabled nanophotonic design.

Quantum Wave-Particle Duality in Free-Electron-Bound-Electron Interaction.

We present a comprehensive relativistic quantum-mechanical theory for interaction of a free electron with a bound electron in a model, where the free electron is represented as a finite-size quantum electron wave packet (QEW) and the bound electron is modeled by a quantum two-level system (TLS). The analysis reveals the wave-particle duality nature of the QEW, delineating the point-particle-like and wavelike interaction regimes and manifesting the physical reality of the wave function dimensions when interacting with matter. This QEW size dependence may be used for interrogation and coherent control of superposition states in a TLS and for enhancement of cathodoluminescence and electron energy-loss spectroscopy in electron microscopy.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run.

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection.

Electromagnetically induced transparency in Raman gain for realizing a superluminal ring laser.

We describe an approach for realizing a superluminal ring laser using a single isotope of Rb vapor by producing electromagnetically induced transparency (EIT) in Raman gain. We show that by modifying the detuning and the intensity of the optical pump field used for generating the two-photon population inversion needed for generating Raman gain, it is possible to generate a dip in the center of the gain profile that can be tuned to produce a vanishingly small group index, as needed for making the Raman laser superluminal. We show that two such lasers, employing two different vapor cells, can be realized simultaneously, operating in counter-propagating directions in the same cavity, as needed for realizing a superluminal ring laser gyroscope.

Outcomes of ST-elevation myocardial infarction by age and sex in a low-income urban community: The Montefiore STEMI Registry.

Objectives: To compare outcomes by age and sex in race/ethnic minorities presenting with ST-elevation myocardial infarction (STEMI), as studies are limited.

Methods: We studied sociodemographics, management, and outcomes in 1208 STEMI patients evaluated for primary percutaneous coronary intervention between 2008 and 2014 at Montefiore Health System (Bronx, NY). A majority of patients self-identified as nonwhite, and nearly two-thirds were young (<45 years) or middle-aged (45-64 years).

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA.

We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star-black hole, and binary black hole systems.

Association of human immunodeficiency virus and hepatitis C virus infection with long-term outcomes post-ST segment elevation myocardial infarction in a disadvantaged urban community.

Background: HIV and HCV have been linked to an increased risk of cardiovascular disease (CVD). Their impact on long-term outcomes following ST-segment myocardial infarction (STEMI) has not been previously studied.

Methods: We leveraged data from a STEMI registry (n = 1208) at an inner-city health system to assess the influence of HIV and HCV on post-STEMI outcomes.