Wavelet analysis of cycle-to-cycle pressure variations in an internal combustion engine

Using a continuous wavelet transform we have analyzed the cycle-to-cycle variations of pressure in an internal combustion engine. The time series of maximum pressure variations are examined for different loading and their wavelet power spectrum is calculated for each load. From the wavelet power spectrum we detected the presence of long, intermediate and short-term periodicities in the pressure signal. It is found that depending on the load, the long and intermediate-term periodicities may span several cycles, whereas the short-period oscillations tend to appear intermittently. Knowledge of these periodicities may be useful to develop effective control strategies for efficient combustion.     

Photochemical synthesis of benz[h]isoquinolines

The synthesis of benz[h]isoquinolines has been achieved using a highly convergent photochemical method. The approach presented provides ready access to biologically active compounds and building blocks not readily available through other methods.     

Quantum Gravity Experimental Physics?

Canonical quantum gravity theories predict apolymer-like structure for space time at the Plancksize. This granularity can be probed using gamma rayburst observations. Quantum gravity effects typically amount to corrections of Planck length size perwavelength. Because the distance to gamma ray burst isvery large as measured in the wavelength of gamma rays,the effects accumulate and are on the brink of being observable. These observations canconstrain certain aspects of the quantum stateunderlying our universe.     

First Measurement of the Nuclear Charge Radii of Short-Lived Lithium Isotopes

A novel method for the determination of nuclear charge radii of lithium isotopes is presented. Precise laser spectroscopic measurements of the isotope shift in the lithium 2s → 3s transition are combined with highly accurate atomic physics calculation of the mass dependent isotope shift to extract the charge-distribution-sensitive information. This approach has been used to determine the charge radii of ^8,9Li for the first time.     

Studien in der Anthracenreihe

Ohne Zusammenfassung     

Black holes in loop quantum gravity: the complete space-time

We consider the quantization of the complete extension of the Schwarzschild space-time using spherically symmetric loop quantum gravity. We find an exact solution corresponding to the semiclassical theory. The singularity is eliminated but the space-time still contains a horizon. Although the solution is known partially numerically and therefore a proper global analysis is not possible, a global structure akin to a singularity-free Reissner-Nordstr?m space-time including a Cauchy horizon is suggested.     

On‐Surface Synthesis of Ethynylene‐Bridged Anthracene Polymers

Engineering low‐band‐gap π‐conjugated polymers is a growing area in basic and applied research. The main synthetic challenge lies in the solubility of the starting materials, which precludes advancements in the field. Here, we report an on‐surface synthesis protocol to overcome such difficulties and produce poly(p‐anthracene ethynylene) molecular wires on Au(111). To this aim, a quinoid anthracene precursor with =CBr₂ moieties is deposited and annealed to 400 K, resulting in anthracene‐based polymers. High‐resolution nc‐AFM measurements confirm the nature of the ethynylene‐bridge bond between the anthracene moieties. Theoretical simulations illustrate the mechanism of the chemical reaction, highlighting three major steps: dehalogenation, diffusion of surface‐stabilized carbenes, and homocoupling, which enables the formation of an ethynylene bridge. Our results introduce a novel chemical protocol to design π‐conjugated polymers based on oligoacene precursors and pave new avenues for advancing the emerging field of on‐surface synthesis.     

Thermally induced cascade pericyclic reaction pathways from tetraene esters

A novel thermally induced cascade pericyclic transformation of a tetraene ester into a complex tricyclic core is reported. This transformation is high yielding and highly selective.     

Realistic clocks, universal decoherence, and the black hole information paradox

Ordinary quantum mechanics is formulated on the basis of the existence of an ideal classical clock external to the system under study. This is clearly an idealization. As emphasized originally by Salecker and Wigner and more recently by others, there exist limits in nature to how "classical" even the best possible clock can be. With realistic clocks, quantum mechanics ceases to be unitary and a fundamental mechanism of decoherence of quantum states arises. We estimate the rate of the universal loss of unitarity using optimal realistic clocks. In particular, we observe that the rate is rapid enough to eliminate the black hole information puzzle: all information is lost through the fundamental decoherence before the black hole can evaporate. This improves on a previous calculation we presented with a suboptimal clock in which only part of the information was lost by the time of evaporation.