Probe-spectroscopy of multi-Doppleron processes

We calculate the weak probe response of a Doppler broadened two-level system, saturated by a strong standing wave. We find that strong coherence features smear the multi-Doppleron resonances. Their origin is discussed.     

Solvent effects of pyridine on the NMR spectra of carboxylic acids. I—study of the acrylic,trans-crotonic and 3-butenoic acids

Proton magnetic resonance spectral parameters of acrylic, trans-crotonic and 3-butenoic acids, their methyl esters and the corresponding alcohols (COOH substituted by CH₂OH) have been measured for 5% (w/v) solutions in carbon tetrachloride and in pyridine-d₅ at 33·5 °C. The total solvent effect of pyridine on the shifts of the skeleton protons of the acid was found to consist of three different effects independently measured from the reference samples.     

It from bit: AI and the laws of nature

The present rate of growth of powerful AI systems motivates an accurate comparison between the notion of computers and the workings of natural sciences. Statements such as “intelligence doesn't require flesh, blood or carbon atoms” or “it's computation all the way down” incite a substrate-independent view, providing shortcuts for Darwinian evolution and the possible appearance of sentient machines. This view is discussed and contrasted from a quantum chemical perspective. The qualitative difference between the developed AI and the evolved HI is recognized and the importance of a material constituent, formulated in terms of energy-temperature, conjugate to an immaterial ingredient, in the context of time-entropy, is pointed out as a necessary feature. The popular dictum “it from bit” does not appear valid unless amended with its obverse “bit from it.”     

Constructing a binary tree from its traversals

This paper shows that a binary tree can be constructed from its preorder and inorder traversals in linear time and space.     

Determination of toxic PCB congeners in biological samples by multidimensional gas chromatography-mass spectrometry (GC/GC/MS)

Summary Multidimensional gas chromatography-mass spectrometry (GC/GC/MS) was used for the determination of coplanar PCB congeners in biological samples. A quadrupole low resolution mass spectrometer was used as the main detector in order to increase the reliability of identification and enable the use of ¹³C-labelled internal standards. The technique was capable to separate these toxic congeners from the complex matrix and decreased the need of sample purification.     

Indexing text with approximate q-grams

We present a new index for approximate string matching. The index collects text q-samples, that is, disjoint text substrings of length q, at fixed intervals and stores their positions. At search time, part of the text is filtered out by noticing that any occurrence of the pattern must be reflected in the presence of some text q-samples that match approximately inside the pattern. Hence the index points out the text areas that could contain occurrences and must be verified. The index parameters permit load balancing between filtering and verification work, and provide a compromise between the space requirement of the index and the error level for which the filtration is still efficient. We show experimentally that the index is competitive against others that take more space, being in fact the fastest choice for intermediate error levels, an area where no current index is useful.     

Detector-Based Calibration Method for High-Accuracy Solar UV Measurements

A novel method for calibrating the absolute responsivity of solar UV spectroradiometers has been developed and tested. The method is based on calibrated filter radiometers constructed from a detector, a precision aperture, a band-pass filter and devices for temperature stabilization. The filter radiometers utilize a trap detector with very low reflectance. The filter and the detector can therefore be characterized separately. As an example the detector-based calibration is compared at 312 nm wavelength with lamp-based calibration by measuring the irradiance of a deuterium lamp with both the filter radiometer and the lamp-calibrated spectroradiometer. The agreement between the results is at the level of 1%, well within the estimated uncertainties of both methods.