Wireless laser spectroscopic sensor node for atmospheric CO2 monitoring—laboratory and field test

We developed a low-power, portable, wireless laser spectroscopic sensor for atmospheric CO₂ monitoring. The sensor is based on tunable diode laser absorption spectroscopy with a 2-μm wavelength VCSEL as a source and wavelength modulation technique for spectroscopic signal detection. The sensor allows measurement of CO₂ concentration changes with a 1σ sensitivity of 0.14 ppmv?Hz^?1/2. This sensor was both laboratory and field tested under varying environmental conditions. It was used to measure a soil respiration rate of topsoil in the lab and of forest floors in the field. Measurement results are compared with those of commercial non-dispersive infrared sensors and very good agreement is found.     

Artificial Neural Networks Performance in WIG20 Index Options Pricing

In this paper, the performance of artificial neural networks in option pricing was analyzed and compared with the results obtained from the Black–Scholes–Merton model, based on the historical volatility. The results were compared based on various error metrics calculated separately between three moneyness ratios. The market data-driven approach was taken to train and test the neural network on the real-world options data from 2009 to 2019, quoted on the Warsaw Stock Exchange. The artificial neural network did not provide more accurate option prices, even though its hyperparameters were properly tuned. The Black–Scholes–Merton model turned out to be more precise and robust to various market conditions. In addition, the bias of the forecasts obtained from the neural network differed significantly between moneyness states. This study provides an initial insight into the application of deep learning methods to pricing options in emerging markets with low liquidity and high volatility.     

Implosion of solid liner for compression of field reversedconfiguration

The design and first successful demonstration of an imploding solid liner with height to diameter ratio, radial convergence, and uniformity suitable for compressing a field reversed configuration is discussed. Radiographs indicated a very symmetric implosion with no instability growth, with ~13x radial compression of the inner liner surface prior to impacting a central measurement unit. The implosion kinetic energy was 1.5 megajoules, 34% of the capacitor stored energy of 4.4 megajoules     

Surface-Induced Dissociation of Multiply Protonated Peptides

We report here surface-induced dissociation spectra of three multiply charged peptides: doubly protonated angiotensin I, doubly protonated renin substrate, and triply protonated melittin. For comparison, the collision-activated dissociation spectra of renin substrate and melittin are also presented. The spectra show that surface-induced dissociation provides structural information on multiply charged peptides at the picomole per microliter sample concentrations compatible with electrospray ionization. For multiply protonated angiotensin I, renin substrate, and melittin, surface collisions (100–165 eV) favor a limited number of fragmentation pathways, which are the same as those favored in collision-activated dissociation experiments.     

Laser desorption ionization of small molecules assisted by tungsten oxide and rhenium oxide particles

Inorganic metal oxides have shown potential as matrices for assisting in laser desorption ionization with advantages over the aromatic acids typically used. Rhenium and tungsten oxides are attractive options due to their high work functions and relative chemical inertness. In this work, it is shown that ReO₃ and WO₃, in microparticle (μP) powder forms, can efficiently facilitate ionization of various types of small molecules and provide minimized background contamination at analyte concentrations below 1 ng/µL. This study shows that untreated inorganic WO₃ and ReO₃ particles are valid matrix options for detection of protonatable, radical, and precharged species under laser desorption ionization. Qualitatively, the WO₃ μP showed improved detection of apigenin, sodiated glucose, and precharged analyte choline, while the ReO₃ μP allowed better detection of protonated cocaine, quinuclidine, ametryn, and radical ions of polyaromatic hydrocarbons at detection levels as low as 50 pg/µL. For thermometer ion survival yield experiments, it was also shown that the ReO₃ powder was significantly softer than α‐cyano‐4‐hydroxycinnaminic acid. Furthermore, it provided higher intensities of cocaine and polyaromatic hydrocarbons, at laser flux values equal to those used with α‐cyano‐4‐hydroxycinnaminic acid. Copyright © 2015 John Wiley & Sons, Ltd.     

Constructing archimedean copulas from diagonal sections

We introduce a family $?$ of functions called diagonal generators. These are convex functions with the properties of diagonal sections of archimedean copulas. We show that to each diagonal generator $f$ there corresponds an archimedean copula $C^f$ with the asymptotic representation $C^f(u_1,u_2)={lim}_{k\to \infty }{f}^k[f^{?k}\left(u_1\right)+f^{?k}\left(u_2\right)?1]$. Moreover, the diagonal section of $C^f$ equals $f$.We characterize archimedean copulas in terms of their asymptotic form. We construct a family ${?}_F$ of diagonal generators, induced by a regular distribution function $F$. We study a differential equation (depending on a function parameter), whose solution is $F$. We give four applications of diagonal generators: to concordance, quadrant dependence, measures of dependence and convergence of copulas.