Minimal Length Scale in Annihilation

Experimental data suggest the existence of a minimal length scale in annihilation process for the reaction e+e- --> gamma gamma (gamma). Nonlinear electrodynamics coupled to gravity and satisfying the weak energy condition predicts, for an arbitrary gauge invariant lagrangian, the existence of a spinning charged electromagnetic soliton asymptotically Kerr-Newman for a distant observer with a gyromagnetic ratio g=2. Its internal structure includes an equatorial disk of de Sitter vacuum which has properties of a perfect conductor and ideal diamagnetic, and displays superconducting behavior within a single spinning soliton. De Sitter vacuum supplies a particle with the finite positive electromagnetic mass related to breaking of space-time symmetry. We apply this approach to interpret the existence of a minimal characteristic length scale in annihilation.Comment: 16 pages, 3 figure

In-Situ Defect Detection in Laser Powder Bed Fusion by Using Thermography and Optical Tomography—Comparison to Computed Tomography

Among additive manufacturing (AM) technologies, the laser powder bed fusion (L-PBF) is one of the most important technologies to produce metallic components. The layer-wise build-up of components and the complex process conditions increase the probability of the occurrence of defects. However, due to the iterative nature of its manufacturing process and in contrast to conventional manufacturing technologies such as casting, L-PBF offers unique opportunities for in-situ monitoring. In this study, two cameras were successfully tested simultaneously as a machine manufacturer independent process monitoring setup: a high-frequency infrared camera and a camera for long time exposure, working in the visible and infrared spectrum and equipped with a near infrared filter. An AISI 316L stainless steel specimen with integrated artificial defects has been monitored during the build. The acquired camera data was compared to data obtained by computed tomography. A promising and easy to use examination method for data analysis was developed and correlations between measured signals and defects were identified. Moreover, sources of possible data misinterpretation were specified. Lastly, attempts for automatic data analysis by data integration are presented

Comparative study of the growth of sputtered aluminum oxide films on organic and inorganic substrates

We present a comparative study of the growth of the technologically highly relevant gate dielectric and encapsulation material aluminum oxide in inorganic and also organic heterostructures. Atomic force microscopy studies indicate strong similarities in the surface morphology of aluminum oxide films grown on these chemically different substrates. In addition, from X-ray reflectivity measurements we extract the roughness exponent \beta of aluminum oxide growth on both substrates. By renormalising the aluminum oxide roughness by the roughness of the underlying organic film we find good agreement with \beta as obtained from the aluminum oxide on silicon oxide (\beta = 0.38 \pm 0.02), suggesting a remarkable similarity of the aluminum oxide growth on the two substrates under the conditions employed

Toward a User Acceptance Model of Autonomous Driving

Autonomous driving is becoming the next big digital disruption in the automotive industry. However, the possibility of integrating autonomous driving vehicles into current transportation systems not only involves technological issues but also requires the acceptance and adoption of users. Therefore, this paper develops a conceptual model for user acceptance of autonomous driving vehicles. The corresponding model is tested through a standardized survey of 470 respondents in Germany. Finally, the findings are discussed in relation to the current developments in the automotive industry, and recommendations for further research are given

Possible Manifestation of a Non-Pointness of the Electron in e+e−e^+e^- Annihilation Reaction at Centre of Mass Energies 55-207 GeV

The experimental data from VENUS, TOPAS, OPAL, DELPHI, ALEPH and L3 collaborations, collected from 1989 to 2003, are applied to study the QED framework through direct contact interaction terms approach, using the annihilation reaction $\rm e^+ e^-\rightarrow \gamma\gamma(\gamma)$. The analysis involves performing of a $\chi^{2}$ test to detect the presence of an excited electron $e^{*}$ and evidence of non-point like behavior in the $e^+e^-$ annihilation zone. The results of the analysis indicate a strong signal, with a confidence level of approximately $5\sigma$, for the presence of an excited electron with a mass of $308\pm 14$ GeV, and a deviation from a point-like behavior of the charge distribution of the electron. The radius of this deviation is $1.57\pm0.07\times 10^{-17}$ cm, which can be interpreted as the size of the electron.Comment: 47 pages, 15 figures, 6 tables. The revised versio

Postsynthesis modification of a cellulose acetate ultrafiltration membrane for applications in water and wastewater treatment

A technique for postsynthesis modification of a cellulose acetate ultrafiltration membrane with possible application in water and wastewater treatment is studied. The technique used an oxidizing agent (persulfate) to develop free radicals on the membrane surface, and that was expected to promote grafting of hydrophilic macromolecules (polyethylene glycol). A chain-transfer agent (2-mercaptoethanol) was tested to control the grafting process, avoiding the formation of long chains that usually lead to high permeability losses in other graft techniques. The modifications aimed at the decrease of the fouling susceptibility of the membrane studied. The possibility of an increase in rejection was also investigated. The membrane was characterized before and after modification, by attenuated total reflectance-Fourier transform-infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and in terms of the rejection of neutral reference solutes. The information given by the different techniques of characterization provided strong evidences of the occurrence of modification, although permeation of (real) foulants was the decisive test. To obtain information about the fouling tendency of the nonmodified and modified membranes, two different kinds of foulants were used: a humic acid (usually found in surface waters) and textile auxiliaries (representing one of the most important industries in Portugal). The results showed an increase in the rejections of the humic acid, and significant improvements in the performance of the membrane with respect to fouling tendency in the case of the textile auxiliarie

Application to the Analysis of Germinal Center Reactions In Vivo

Simultaneous detection of multiple cellular and molecular players in their native environment, one of the keys to a full understanding of immune processes, remains challenging for in vivo microscopy. Here, we present a synergistic strategy for spectrally multiplexed in vivo imaging composed of (i) triple two-photon excitation using spatiotemporal synchronization of two femtosecond lasers, (ii) a broad set of fluorophores with emission ranging from blue to near infrared, (iii) an effective spectral unmixing algorithm. Using our approach, we simultaneously excite and detect seven fluorophores expressed in distinct cellular and tissue compartments, plus second harmonics generation from collagen fibers in lymph nodes. This enables us to visualize the dynamic interplay of all the central cellular players during germinal center reactions. While current in vivo imaging typically enables recording the dynamics of 4 tissue components at a time, our strategy allows a more comprehensive analysis of cellular dynamics involving 8 single-labeled compartments. It enables to investigate the orchestration of multiple cellular subsets determining tissue function, thus, opening the way for a mechanistic understanding of complex pathophysiologic processes in vivo. In the future, the design of transgenic mice combining a larger spectrum of fluorescent proteins will reveal the full potential of our method

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Rapid cooling rates and steep temperature gradients are characteristic of additively manufactured parts and important factors for the residual stress formation. This study examined the influence of heat accumulation on the distribution of residual stress in two prisms produced by Laser Powder Bed Fusion (LPBF) of austenitic stainless steel 316L. The layers of the prisms were exposed using two different border fill scan strategies: one scanned from the centre to the perimeter and the other from the perimeter to the centre. The goal was to reveal the effect of different heat inputs on samples featuring the same solidification shrinkage. Residual stress was characterised in one plane perpendicular to the building direction at the mid height using Neutron and Lab X-ray diffraction. Thermography data obtained during the build process were analysed in order to correlate the cooling rates and apparent surface temperatures with the residual stress results. Optical microscopy and micro computed tomography were used to correlate defect populations with the residual stress distribution. The two scanning strategies led to residual stress distributions that were typical for additively manufactured components: compressive stresses in the bulk and tensile stresses at the surface. However, due to the different heat accumulation, the maximum residual stress levels differed. We concluded that solidification shrinkage plays a major role in determining the shape of the residual stress distribution, while the temperature gradient mechanism appears to determine the magnitude of peak residual stresses