Impact of hedging pressure on implied volatility in Financial Times and London Stock Exchange (FTSE) market

This paper examines the impact of net buying pressure and the event of 9/11 on the implied volatility of the U.K. FTSE 100 (Financial Times and the London Stock Exchange) index options. Our findings indicate that when effects such as financial leverage, information flow and mean reversion are held constant, the net buying pressure of the out-of-the-money put options plays a dominant role in determining the shape of the implied volatility function. Further, the event of 9/11 has a transitory influence on the implied volatility change. Our results also support the notion that hedging pressure can help explain the difference between implied volatility and realized volatility

Positive exchange bias in ferromagnetic La0.67Sr0.33MnO3 / SrRuO3 bilayers

Epitaxial La0.67Sr0.33MnO3 (LSMO)/ SrRuO3 (SRO) ferromagnetic bilayers have been grown on (001) SrTiO3 (STO) substrates by pulsed laser deposition with atomic layer control. We observe a shift in the magnetic hysteresis loop of the LSMO layer in the same direction as the applied biasing field (positive exchange bias). The effect is not present above the Curie temperature of the SRO layer (), and its magnitude increases rapidly as the temperature is lowered below . The direction of the shift is consistent with an antiferromagnetic exchange coupling between the ferromagnetic LSMO layer and the ferromagnetic SRO layer. We propose that atomic layer charge transfer modifies the electronic state at the interface, resulting in the observed antiferromagnetic interfacial exchange coupling.Comment: accepted to Applied Physics Letter

Towards run-time monitoring of web services conformance to business-level agreements

Web service behaviour is currently specified in a mixture of ways, often using methods that are only partially complete. These range from static functional specifications, based on interfaces in WSDL and preconditions in RIF, to business process simulations using executable process-based models such as BPEL, to detailed quality of service (QoS) agreements laid down in a service level agreement (SLA). This paper recognises that something similar to a SLA is required at the higher business level to govern the contract between service producers, brokers and consumers. We call this a business level agreement (BLA) and within this framework, seek to unify disparate aspects of functional specification, QoS and run-time verification. We propose that the method for validating a web service with respect to its advertised BLA should be based on run-time service monitoring. This is a position paper towards defining these goals

Search for Zs1+Z^{+}_{s1} and Zs2+Z^{+}_{s2} strangeonium-like structures

Theoretically, it has been presumed from an effective Lagrangian calculation that there could exist two charged strangeonium-like molecular states $Z^{+}_{s1}$ and $Z^{+}_{s2}$, with $K\bar{K}^{*}$ and $K^{*}\bar{K}^{*}$ configurations respectively. In the framework of QCD sum rules, we predict that masses of $Z^{+}_{s1}$ ($K\bar{K}^{*}$) and $Z^{+}_{s2}$ ($K^{*}\bar{K}^{*}$) are $1.85\pm0.14 GeV$ and $2.02\pm0.15 GeV$ respectively, which are both above their respective two meson thresholds. We suggest to put in practice the search for these two charged strangeonium-like structures in future experiments.Comment: 7 pages, 4 eps figures; the version accepted for publication in PRD. arXiv admin note: text overlap with arXiv:1203.070

Energy Calibration of the JLab Bremsstrahlung Tagging System

In this report, we present the energy calibration of the Hall B bremsstrahlung tagging system at the Thomas Jefferson National Accelerator Facility. The calibration was performed using a magnetic pair spectrometer. The tagged photon energy spectrum was measured in coincidence with $e^+e^-$ pairs as a function of the pair spectrometer magnetic field. Taking advantage of the internal linearity of the pair spectrometer, the energy of the tagging system was calibrated at the level of $\pm 0.1$. The absolute energy scale was determined using the $e^+e^-$ rate measurements close to the end-point of the photon spectrum. The energy variations across the full tagging range were found to be $<3$ MeV.Comment: 15 pages, 12 figure

Alloying effect on the oxidation behavior of a ductile Al0.5Cr0.25Nb0.5Ta0.5Ti1.5 refractory high-entropy alloy

Refractory high-entropy alloys (RHEAs) are widely studied because of their promising potential for ultrahigh-temperature applications. One key challenge towards the development of RHEAs as high temperature structural materials is to concurrently achieve optimum oxidation resistance and mechanical properties. Here in this work, the effect of alloying on the oxidation behavior of ductile RHEAs was studied. Specifically, a ductile RHEA, Al0.5Cr0.25Nb0.5Ta0.5Ti1.5, was alloyed with Al and Zr aiming to improve its oxidation resistance. The two modified RHEAs, Al0.75Cr0.25Nb0.5Ta0.5Ti1.5 and Al0.5Cr0.25Nb0.5Ta0.5Ti1.5Zr0.01, indeed show enhanced oxidation resistance at 800 degrees C and 1,100 degrees C, compared with Al0.5Cr0.25Nb0.5Ta0.5Ti1.5. In addition, all three RHEAs studied here show an excellent oxidation resistance at 800 degrees C compared with other RHEAs, although there is still a large space to further improve their performance at 1,100 degrees C. Internal oxidation and even nitridation are still present after oxidation exposure, indicating further efforts are required to form protective oxide scales on the surface of ductile RHEAs. Nevertheless, the work is expected to shed some light on future directions of improving the oxidation of ductile RHEAs, via the alloying route

Scaling of the time-mean characteristics in the polygonal cylinder near-wake

The near wake of the polygonal cylinder with the side number N = 3 ~ ∞ is systematically studied based on particle image velocimetry (PIV) and load-cell measurements. Each cylinder is examined for two orientations, with either one leading side or leading corner. The Reynolds number Re = (1.0 ∼ 6.0) × 104 , defined by the longitudinally projected cylinder width. The dependence of the wake characteristic parameters on the cylinder orientation and N is discussed, and wake scaling analysis is conducted based on these parameters. It is found that the velocity deficit and half width of the wake scale well with the reverse flow zone length and recirculation bubble width, whilst the Strouhal number, drag and fluctuating lift coefficients scale well with the vortex formation length and wake width. The unveiled scaling relationships cast insight into the intrinsic physical connections between the aerodynamic forces and vortex formation and between the polygonal cylinder wakes of N = 3 ~ ∞, suggesting that the understanding of the time-mean wake behind individual polygonal cylinder can be unified to that of the circular cylinder wake

In situ tropical peatland ire emission factors and their variability, as determined by field measurements in peninsula Malaysia

Fires in tropical peatlands account for >25% of estimated total greenhouse gas emissions from deforestation and degradation. Despite significant global and regional impacts, our understanding of specific gaseous fire emission factors (EFs) from tropical peat burning is limited to a handful of studies. Furthermore, there is substantial variability in EFs between sampled fires and/or studies. For example, methane EFs vary by 91% between studies. Here we present new fire EFs for the tropical peatland ecosystem; the first EFs measured for Malaysian peatlands, and only the second comprehensive study of EFs in this crucial environment. During August 2015 (under El Niño conditions) and July 2016, we embarked on field campaigns to measure gaseous emissions at multiple peatland fires burning on deforested land in Southeast Pahang (2015) and oil palm plantations in North Selangor (2016), Peninsula Malaysia. Gaseous emissions were measured using open-path Fourier transform infrared spectroscopy. The IR spectra were used to retrieve mole fractions of 12 different gases present within the smoke (including carbon dioxide and methane), and these measurements used to calculate EFs. Peat samples were taken at each burn site for physicochemical analysis and to explore possible relationships between specific physicochemical properties and fire EFs. Here we present the first evidence to indicate that substrate bulk density affects methane fire EFs reported here. This novel explanation of interplume, within-biome variability, should be considered by those undertaking greenhouse gas accounting and haze forecasting in this region and is of importance to peatland management, particularly with respect to artificial compaction