The Radiated Energy Budget of Chromospheric Plasma in a Major Solar Flare Deduced From Multi-Wavelength Observations

This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form of nonthermal electrons. Hard X-ray observations from RHESSI were used to track the evolution of the parameters of the nonthermal electron distribution to reveal the total power contained in flare accelerated electrons. By integrating over the duration of the impulsive phase, the total energy contained in the nonthermal electrons was found to be $>2\times10^{31}$ erg. The response of the lower solar atmosphere was measured in the free-bound EUV continua of H I (Lyman), He I, and He II, plus the emission lines of He II at 304\AA\ and H I (Ly$\alpha$) at 1216\AA\ by SDO/EVE, the UV continua at 1600\AA\ and 1700\AA\ by SDO/AIA, and the WL continuum at 4504\AA, 5550\AA, and 6684\AA, along with the Ca II H line at 3968\AA\ using Hinode/SOT. The summed energy detected by these instruments amounted to $\sim3\times10^{30}$ erg; about 15% of the total nonthermal energy. The Ly$\alpha$ line was found to dominate the measured radiative losses. Parameters of both the driving electron distribution and the resulting chromospheric response are presented in detail to encourage the numerical modelling of flare heating for this event, to determine the depth of the solar atmosphere at which these line and continuum processes originate, and the mechanism(s) responsible for their generation.Comment: 14 pages, 18 figures. Accepted for publication in Astrophysics Journa

Nonlinear optics: Nonlinear virtues of multimode fibre

Supercontinuum generation — the extreme spectral broadening of laser light (a span from the ultraviolet to the mid-infrared is possible) — is a fascinating process that takes place in a dispersive and strongly nonlinear optical medium

A phase-space approach to non-stationary nonlinear systems

A phase-space formulation of non-stationary nonlinear dynamics including both Hamiltonian (e.g., quantum-cosmological) and dissipative (e.g., dissipative laser) systems reveals an unexpected affinity between seemly different branches of physics such as nonlinear dynamics far from equilibrium, statistical mechanics, thermodynamics, and quantum physics. One of the key insights is a clear distinction between the "vacuum" and "squeezed" states of a non-stationary system. For a dissipative system, the "squeezed state" (or the coherent "concentrate") mimics vacuum one and can be very attractable in praxis, in particular, for energy harvesting at the ultrashort time scales in a laser or "material laser" physics including quantum computing. The promising advantage of the phase-space formulation of the dissipative soliton dynamics is the possibility of direct calculation of statistical (including quantum) properties of coherent, partially-coherent, and non-coherent dissipative structure without numerically consuming statistic harvesting.Comment: 11th CHAOS Conference, 5 - 8 June 2018, Rome, Italy; 13 pages, 9 figure

Natural evolution of desmoplastic fibroblastoma on magnetic resonance imaging: a case report

<p>Abstract</p> <p>Introduction</p> <p>Desmoplastic fibroblastoma (collagenous fibroma) is a recently described tumor thought to arise predominantly from subcutaneous tissue or skeletal muscle. The natural evolution of this tumor on magnetic resonance imaging has never been described, to the best of our knowledge. We herein report a case of desmoplastic fibroblastoma arising in the thigh and show the longitudinal magnetic resonance imaging findings.</p> <p>Case presentation</p> <p>A 60-year-old Japanese man presented with swelling of the medial side of his right thigh, and he complained of nighttime pain and slight tenderness. Magnetic resonance imaging demonstrated a 4 × 4 cm mass in the right thigh. Open biopsy was performed. The mass was diagnosed histologically as a benign fibrous tumor, and we maintained follow-up without surgical therapy. After one year, magnetic resonance imaging showed an increase in tumor size to 4 × 5 cm, but the histologic findings were the same as those obtained one year earlier. Resection was performed with narrow surgical margins. Pathologic diagnosis was desmoplastic fibroblastoma. Two years after surgery, the patient is free from pain and shows no signs or symptoms of recurrence.</p> <p>Conclusion</p> <p>The natural evolution of desmoplastic fibroblastoma is characterized by no changes in patterns on magnetic resonance imaging despite increasing size. This finding is clinically helpful for distinguishing desmoplastic fibroblastoma with increasing pain from the desmoid tumor.</p

Gain through losses in nonlinear optics

Instabilities of uniform states are ubiquitous processes occurring in a variety of spatially extended nonlinear systems. These instabilities are at the heart of symmetry breaking, condensate dynamics, self-organization, pattern formation and noise amplification across diverse disciplines, including physics, chemistry, engineering and biology. In nonlinear optics, modulation instabilities are generally linked to the so-called parametric amplification process, which occurs when certain phase-matching or quasi-phase-matching conditions are satisfied. In the present review article, we summarize the principle results on modulation instabilities and parametric amplification in nonlinear optics, with special emphasis on optical fibres. We then review state-of-the-art research about a peculiar class of modulation instabilities and signal amplification processes induced by dissipation in nonlinear optical systems. Losses applied to certain parts of the spectrum counterintuitively lead to the exponential growth of the damped mode themselves, causing gain through losses. We discuss the concept of imaging of losses into gain, showing how to map a given spectral loss profile into a gain spectrum. We demonstrate with concrete examples that dissipation-induced modulation instability, apart from being of fundamental theoretical interest, may pave the way towards the design of a new class of tuneable fibre-based optical amplifiers, optical parametric oscillators, frequency comb sources and pulsed lasers

Oral Insulin

Oral insulin is an exciting area of research and development in the field of diabetology. This brief review covers the various approaches used in the development of oral insulin, and highlights some of the recent data related to novel oral insulin preparation

Stokes solitons in optical microcavities

Solitons are wave packets that resist dispersion through a self-induced potential well. They are studied in many fields, but are especially well known in optics on account of the relative ease of their formation and control in optical fibre waveguides. Besides their many interesting properties, solitons are important to optical continuum generation, in mode-locked lasers, and have been considered as a natural way to convey data over great distances. Recently, solitons have been realized in microcavities, thereby bringing the power of microfabrication methods to future applications. This work reports a soliton not previously observed in optical systems, the Stokes soliton. The Stokes soliton forms and regenerates by optimizing its Raman interaction in space and time within an optical potential well shared with another soliton. The Stokes and the initial soliton belong to distinct transverse mode families and benefit from a form of soliton trapping that is new to microcavities and soliton lasers in general. The discovery of a new optical soliton can impact work in other areas of photonics, including nonlinear optics and spectroscopy

Cellular Radiosensitivity: How much better do we understand it?

Purpose: Ionizing radiation exposure gives rise to a variety of lesions in DNA that result in genetic instability and potentially tumorigenesis or cell death. Radiation extends its effects on DNA by direct interaction or by radiolysis of H2O that generates free radicals or aqueous electrons capable of interacting with and causing indirect damage to DNA. While the various lesions arising in DNA after radiation exposure can contribute to the mutagenising effects of this agent, the potentially most damaging lesion is the DNA double strand break (DSB) that contributes to genome instability and/or cell death. Thus in many cases failure to recognise and/or repair this lesion determines the radiosensitivity status of the cell. DNA repair mechanisms including homologous recombination (HR) and non-homologous end-joining (NHEJ) have evolved to protect cells against DNA DSB. Mutations in proteins that constitute these repair pathways are characterised by radiosensitivity and genome instability. Defects in a number of these proteins also give rise to genetic disorders that feature not only genetic instability but also immunodeficiency, cancer predisposition, neurodegeneration and other pathologies. Conclusions: In the past fifty years our understanding of the cellular response to radiation damage has advanced enormously with insight being gained from a wide range of approaches extending from more basic early studies to the sophisticated approaches used today. In this review we discuss our current understanding of the impact of radiation on the cell and the organism gained from the array of past and present studies and attempt to provide an explanation for what it is that determines the response to radiation