On quantum corrections in higher-spin theory in flat space

We consider an interacting theory of an infinite tower of massless higher-spin fields in flat space with cubic vertices and their coupling constants found previously by Metsaev. We compute the one-loop bubble diagram part of the self-energy of the spin 0 member of the tower by summing up all higher-spin loop contributions. We find that the result contains an exponentially UV divergent part and we discuss how it could be cancelled by a tadpole contribution depending on yet to be determined quartic interaction vertex. We also compute the tree-level four-scalar scattering amplitude due to all higher-spin exchanges and discuss its inconsistency with the BCFW constructibility condition. We comment on possible relation to similar computations in AdS background in connection with AdS/CFT.Comment: 34 pages, minor corrections and references adde

Forced spreading over superhydrophobic and copper surfaces

Dynamic spreading over superhydrophobic and copper surfaces was studied experimentally under the condition of contact line movement with speed greater than 1 mm/sec. Three modes of spreading of distilled water drop over copper surfaces with sufficient typical roughness (0.591, 5.190 and 6.210 μM) were detected. The first one is drop formation when the contact line speed and dynamic contact angle increase sharply. The second mode is spreading of a drop, which is characterized by a monotonic decrease in the contact line speed and dynamic contact angle. The third one is a formation of an equilibrium contact angle at a constant wetted area (the contact line speed tends to zero, and spreading of a drop occurs as long as the driving force is greater than zero). Some features in spreading were detected on superhydrophobic surface with parameter roughness of 0.751μm compared to other substrates. During drop formation after sharp increase in the contact line speed and dynamic contact angle, there is a mode which is accompanied by a decrease in the contact line speed and monotonic increase in the advancing dynamic contact angle

Fabrication and Characterization of an 8 × 8 Terahertz Photoconductive Antenna Array for Spatially Resolved Time Domain Spectroscopy and Imaging Applications

ABSTRACT: Terahertz (THz) technology is promising in several applications such as imaging, spectroscopy and communications. Among several methods in the generation and detection of THz waves, a THz timedomain system that is developed using photoconductive antennas (PCA) as emitter and detector presents several advantages such as simple alignment, low cost, high performance etc. In this work, we report the design, fabrication and characterization of a 2-D PCA array that is capable of detecting both the amplitude and phase of the THz pulse. The PCA array is fabricated using LT-GaAs and has 8 channels with 64 pixels (8 × 8). A novel approach using a spatial light modulator (SLM) to steer and focus the infrared probe beam towards pixels of the PCA array is presented. Each channel records the photocurrent generated by the THz signal (amplitude and phase) separately and frequencies up to 1.4 THz can be detected. Furthermore, the parameters such as directional time delay of the THz pulse, crosstalk between the channels etc., were characterized. Finally, we show that the proposed 2D PCA array design is flexible and can be used for accelerated THz spectral image acquisition

Empirically Estimated Heats of Combustion of Oxygenated Hydrocarbon Bio-type Oils

An empirical method is proposed by which the heats of combustion of oxygenated hydrocarbon oils, typically found from wood pyrolysis, may be calculated additively from empirically predicted heats of combustion of individual compounds. The predicted values are in turn based on four types of energetically inequivalent carbon and four types of energetically inequivalent hydrogen atomic energy values. A method is also given to estimate the condensation heats of oil mixtures based on the presence of four types of intermolecular forces. Agreement between predicted and experimental values of combustion heats for a typical mixture of known compounds was ± 2% and < 1% for a freshly prepared mixture of known compounds