All-fiber optical supercontinuum sources in 1.7-3.2 μm range

We report supercontinuum generation in the 1.7-2.9 μm range with up to 3.08 W of output power and in the range of 1.93-3.18 μm with up to 3.8 W of output power from all-fiber MOPA pulsed systems with Tm-doped fiber mode-locked seed laser. Supercontinuum generation was demonstrated in nonlinear germanate fibers and fluoride (ZBLAN) fibers. The supercontinuum bandwidth reached 1250 nm at -10 dB level

Features of disease course of some forms of herpesvirus infection

Among the many factors that directly affect the immune system, infections caused by the herpes virus deserve special attention. In recent years, there has been an increase in the number of patients suffering from chronic recurrent herpesvirus infections, which in many cases are accompanied by severe general malaise and a number of therapeutic complaints. Today about 80-95% of the population is infected with Epstein-Barr virus EBV. Primary infection of EBV leads to lifelong persistence of the pathogen with possible periodic reactivation under the action of various immunosuppressive factors, which leads to chronic forms of the disease. EBV can cause chronic manifest and erased forms of the disease, running on the type of chronic mononucleosis. Thus, the study of the nature of clinical and laboratory changes in patients with chronic EBV infection and the peculiarities of the disease is an urgent problem of our time. The aim of this work was to study the features of the course of chronic EBV infection. We performed a comprehensive clinical and laboratory examination of 128 patients with chronic EBV infection (reactivation period). The diagnosis of chronic EBV infection was established on the basis of medical history, complaints, the presence of specific antibodies to EBV antigens and the detection of virus DNA in the blood. Studies of clinical blood tests of patients with chronic EBV infection and the control group showed differences. Thus, in patients with chronic EBV infection, a significantly elevated ESR level was found - 12.6 ± 1.8 versus 4.5 ± 1.1 inthe control group (p <0.05). The levels of erythrocytes, hemoglobin and platelets did not differ significantly from the control group. In patients with chronic EBV infection, there was a decrease in the level of leukocytes (5.13 ± 0.22) x 109/ l against (6.20 ± 1.8) x 109/l in the control group (p> 0.05), but these changes did not go beyond the norms established for healthy people. Analysis of the leukocyte formula revealed the presence of patients with chronic WEB infection with a significant increase in the relative content of lymphocytes - 42.50 ± 2.0% against 33.70 ± 2.68% (p <0.05) and monocytes - 11.15 ± 0.9% vs. 3.0 ± 0.6% (p <0.05), which was the basis for confirming the presence of a chronic infectious process. In general, 94.8% of patients with chronic EBV infection had lymphocytosis and 82.5% had monocytosis. The relative number of neutrophils in patients with chronic WEB infection averaged 45.35 ± 4.1% against 61.7 ± 3.8% in the control group (p <0.05); the relative number of eosinophils and basophils was within normal limits. When studying the absolute number of lymphocytes and monocytes in patients with chronic EBV infection, there was a tendency to increase them and their level was on average (2.13 ± 0.7) x 109/ l and (0.51 ± 0.08) x 109/ l against (2.39 ± 0.7) x 109/ l and (0.47 ± 0.08) x 109/ l in the control group (p> 0.05). The absolute number of neutrophils in patients with chronic WEB infection was significantly lower than in the control group and was 2.70 x 109/ l versus 4.21 x 109/ l (p <0.05). The study of the absolute number of eosinophils and basophils in patients with chronic EBV infection did not reveal statistically significant differences compared with the control group. Thus, according to the results of our study, we found that patients with chronic EBV infection among the clinical manifestations were most often chronic tonsillitis, chronic fatigue syndrome and peripheral lymphadenopathy. Analysis of the results of laboratory studies revealed a significant increase in ESR, relative lymphocytes and monocytes, as well as a decrease in absolute and relative neutrophils, compared with the control group of patients, indicating a shift in white blood cell count, characteristic of the viral etiology of the disease what associated with the EBV.DOI: 10.5281/zenodo.403896

YDFL operating in 1150-1200-nm spectral domain

A family of high-power Yb-doped fiber lasers operated in the range of 1150-1180 nm with output powers of up to 35 W and optical efficiencies up to 60% is realized. Operation at 1200 nm is also demonstrated. Amplified spontaneous emission increase with output power increase is analyzed in frames of the inhomogeneous broadening concept

Flat-top supercontinuum and tunable femtosecond fiber laser sources at 1.9-2.5 μm

We report the high-energy flat-top supercontinuum covering the mid-infrared wavelength range of 1.9-2.5 μm as well as electronically tunable femtosecond pulses between 1.98-2.22 μm directly from the thulium-doped fiber laser amplifier. Comparison of experimental results with numerical simulations confirms that both sources employ the same nonlinear optical mechanism - Raman soliton frequency shift occurring inside the Tm-fiber amplifier. To illustrate that, we investigate two versions of the compact diode-pumped SESAM mode-locked femtosecond thulium-doped all-silica-fiber-based laser system providing either broadband supercontinuum or tunable Raman soliton output, depending on the parameters of the system. The first system operates in the Raman soliton regime providing femtosecond pulses tunable between 1.98-2.22 μm. Wide and continuous spectral tunability over 240 nm was realized by changing only the amplifier pump diode current. The second system generates high-energy supercontinuum with the superior spectral flatness of better than 1 dB covering the wavelength range of 1.9-2.5 μm, with the total output energy as high as 0.284 μJ, the average power of 2.1 W at 7.5 MHz repetition rate. We simulate the amplifier operation in the Raman soliton self-frequency shift regime and discuss the role of induced Raman scattering in supercontinuum formation inside the fiber amplifier. We compare this system with a more traditional 1.85-2.53 μm supercontinuum source in the external highly-nonlinear commercial chalcogenide fiber using the Raman soliton MOPA as an excitation source. The reported systems1 can be readily applied to a number of industrial applications in the mid-IR, including sensing, stand-off detection, medical surgery and fine material processing

Li+ protects nerve cells against destabilization of Ca2+ homeostasis and delayed death caused by removal of external Na+

AbstractIn experiments with fura-2 loaded cultured rat cerebellar granule cells we have compared the changes in [Ca2+]i homeostasis produced by replacement of external Na+ with the organic cation N-methyl-d-glucamine (NMDG) or Li+. The Na+/NMDG replacement caused an increase in baseline [Ca2+]i and a considerable delay in [Ca2+]i recovery following a glutamate (Glu) pulse in almost all the cells. In contrast Na+/Li+ replacement usually did not change baseline [Ca2+]i and produced only a small (if any) delay in the post-glutamate [Ca2+]i recovery. Previously [Storozhevykh et al. (1998) FEBS Lett. 431, 215–218] we revealed that perturbation of [Ca2+]i homeostasis caused by Na+/NMDG replacement cannot be explained by a reversal of the Na+/Ca2+ exchange but is mainly due to Ca2+ influx through NMDA channels activated by Na+ dependent release of endogenous excitatory amino acids (`reversed Glu uptake'). In the present work we confirmed this conclusion and obtained evidence suggesting that in contrast to NMDG Li+ interferes with the `reversed Glu uptake' triggered by removal of external Na+. Thus it has been shown that the addition of Li+ (20 mM) to a Na+-free NMDGcontaining solution suppressed both the perturbation of [Ca2+]i homeostasis and delayed neuronal death caused by Na+/NMDG replacement. Li+ is also able to abolish the [Ca2+]i response induced by PDC which at high concentrations (>200 μM) is shown to stimulate the release of endogenous Glu. In contrast to Na+/Li+, Na+/NMDG replacement greatly enhances [Ca2+]i increase caused by PDC. Control experiments showed that Na+/Li+ replacement does not decrease the [Ca2+]i response to the Glu pulse. Therefore we concluded that a considerable quantitative difference between the effects of Na+/NMDG and Na+/Li+ replacements on both [Ca2+]i homeostasis and cell viability resulted mainly from the ability of Li+ to attenuate the release of endogenous Glu in response to the removal of external Na+

A route to high peak power and energy scaling in the mid-IR chirped-pulse oscillator-amplifier laser systems

The paper introduces a new route towards the ultrafast high laser peak power and energy scaling in a hybrid mid-IR chirped pulse oscillator-amplifier (CPO-CPA) system, without sacrificing neither the pulse duration nor energy. The method is based on using a CPO as a seed source allowing the beneficial implementation of a dissipative soliton (DS) energy scaling approach, coupled with a universal CPA technique. The key is avoiding a destructive nonlinearity in the final stages of an amplifier and compressor elements by using a chirped high-fidelity pulse from CPO. Our main intention is to realize this approach in a Cr2+:ZnS-based CPO as a source of energy-scalable DSs with well-controllable phase characteristics for a single-pass Cr2+:ZnS amplifier. A qualitative comparison of experimental and theoretical results provides a road map for the development and energy scaling of the hybrid CPO-CPA laser systems, without compromising pulse duration. The suggested technique opens up a route towards extremely intense ultra-short pulses and frequency combs from the multi-pass CPO-CPA laser systems that are particularly interesting for real-life applications in the mid-IR spectral range from 1 to 20 um.Comment: 16 pages, 14 figure

Supercontinuum generation in mid-IR using chalcogenide and germanate nonlinear fiber

We demonstrate mid-infrared (mid-IR) supercontinuum generation with bandwidth from 2 to 2.8 μm at 20 dB below the peak in nonlinear step-index chalcogenide fiber using femtosecond mid-IR pulses directly from the oscillator. We compare the results with a supercontinuum generated in a silica-based high germanium content fiber. Supercontinuum generation occurs at 90 mW of launched average pump power that is equal to the 0.9 nJ pulse energy. The distinctive feature of the obtained supercontinuum is its stability and coherence due to the deterministic supercontinuum generation by the femtosecond pump pulses

Shock Breakout in Type II Plateau Supernovae: Prospects for High Redshift Supernova Surveys

Shock breakout is the brightest radiative phenomenon in a supernova (SN) but is difficult to be observed owing to the short duration and X-ray/ultraviolet (UV)-peaked spectra. After the first observation from the rising phase reported in 2008, its observability at high redshift is attracting enormous attention. We perform multigroup radiation hydrodynamics calculations of explosions for evolutionary presupernova models with various main-sequence masses $M_{\rm MS}$, metallicities $Z$, and explosion energies $E$. We present multicolor light curves of shock breakout in Type II plateau SNe, being the most frequent core-collapse SNe, and predict apparent multicolor light curves of shock breakout at various redshifts $z$. We derive the observable SN rate and reachable redshift as functions of filter $x$ and limiting magnitude $m_{x,{\rm lim}}$ by taking into account an initial mass function, cosmic star formation history, intergalactic absorption, and host galaxy extinction. We propose a realistic survey strategy optimized for shock breakout. For example, the $g'$-band observable SN rate for $m_{g',{\rm lim}}=27.5$ mag is 3.3 SNe degree$^{-2}$ day$^{-1}$ and a half of them locates at $z\geq1.2$. It is clear that the shock breakout is a beneficial clue to probe high-$z$ core-collapse SNe. We also establish ways to identify shock breakout and constrain SN properties from the observations of shock breakout, brightness, time scale, and color. We emphasize that the multicolor observations in blue optical bands with $\sim$ hour intervals, preferably over $\geq2$ continuous nights, are essential to efficiently detect, identify, and interpret shock breakout.Comment: 26 pages, 23 figures. Accepted for publication in the Astrophysical Journal Supplement Serie