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C A Chatzidimitriou-Dreismann

Publications and source records attributed to C A Chatzidimitriou-Dreismann.

8 recordsLinked to original sources
PubMed2003

Comparison of electron and neutron compton scattering from entangled protons in a solid polymer.

We present, for the first time, a direct comparison between electron (ECS) and neutron (NCS) Compton scattering results from protons of a solid polymer. The momentum distributions of hydrogen obtained from ECS and NCS are in excellent agreement. In both experiments, a strong "anomalous" shortfall in the scattering intensity of protons [first detected in liquid water with NCS [Phys. Rev. Lett. 79, 2839 (1997)]]] is found ranging from about 20% up to 50%, depending on the momentum transfer applied. The characteristic times of electron- and neutron-proton collisions lie in the subfemtosecond range. The presented ECS and NCS results provide further direct evidence for this striking effect, which has been ascribed to attosecond quantum entanglement of the protons.

Journal Article↗
PubMed2001

Entanglement of protons in organic molecules: an attosecond neutron scattering study of C [bond] H bond breaking.

Interactions between adjacent particles of condensed phases can lead to quantum correlation phenomena, like quantum interference, entanglement, delocalization, and "Schrödinger's cat" states. Such correlations are theoretically expected to be extremely short-lived because of environmental disturbances. Here, we present experimental evidence for quantum entanglement between well localized protons of C [bond] H bonds of 2-isobutoxyethanol dissolved in D(2)O. The applied experimental method is neutron Compton scattering (NCS), which has a characteristic time window in the subfemtosecond time range. Our NCS results reveal that, in the subfemtosecond time scale, the measured cross-section density, and thus, in simple terms, the effectively present concentration, of the H atoms is "anomalously" reduced by approximately 20%. Affecting the microdynamics of protons of covalent C [bond] H bonds, this novel effect may have a broad range of chemical and biological applications.

Journal Article↗
PubMed1996

Lack of biological significance in the 'linguistic features' of noncoding DNA--a quantitative analysis.

Recently, the application of two statistical methods (related to Zipf's distribution and Shannon's redundancy), called 'linguistic' tests, to the primary structure of DNA sequences of living organisms has excited considerable interest. Of particular importance is the claim that noncoding DNA sequences in eukaryotes display specific 'linguistic' features, being reminiscent of natural languages. Furthermore, this implies that noncoding regions of DNA may carry some new, thus far unknown, biological information which is revealed by these tests. In this paper these claims are tested quantitatively. With the aid of computer simulations of natural DNA sequences, and by applying the same 'linguistic' tests to both natural and artificial sequences, we investigate in detail the reasons of the appearance of the claimed 'linguistic' features and the associated differences between coding and noncoding DNAs. The presented results show quantitatively that the 'linguistic' tests failed to reveal any new biological information in (noncoding or coding) DNA.

Base Composition↗
PubMed1994

A quantitative test of long-range correlations and compositional fluctuations in DNA sequences.

Recent findings concerning long-range correlations and fractals in intron-containing DNA sequences of living organisms are tested qualitatively and quantitatively. Extending previous studies, we demonstrate that these findings are trivially equivalent to variations of the base-pair composition in different regions of a DNA sequence. It is shown explicitly that a well-defined scaling or fractal exponent does not exist anywhere. Comparisons of natural DNAs with computer-generated, artificial sequences are made. The present study reveals that certain natural DNA sequences (especially those with compact genomes) do have stochastic characteristics which are intrinsically different from artificial sequences. The results for 21 DNA sequences of various types from widely different taxa are reported.

Animals↗
PubMed1994

Variations in base pair composition and associated long-range correlations in DNA sequences--computer simulation results.

Recently, the possible occurrence of long-range correlations between nucleotides in DNA sequences of living organisms has excited considerable interest. Of particular importance is the claim that only intron-containing sequences exhibit these correlations. Different investigations, however, have disproved the claimed difference between intron-containing and intron-less DNA sequences. Moreover, very recent investigations pointed out that the long-range correlations appear only if relatively large variations in nucleotide composition along the DNA sequence are present. Furthermore, some examples demonstrated that these variations may have clear biological reasons. In this paper we investigate in detail, with the aid of computer simulations, the connection between compositional heterogeneity of a DNA sequence and the appearance of long-range correlations. As an explicit example, the DNA sequence of the lambda-phage is compared with different artificial sequences of similar compositional heterogeneity. The results demonstrate that the variations of the nucleotide composition along the sequence can fully account for all properties of the claimed long-range correlations. New results of extensive computer simulations are presented which clearly demonstrate how the apparent 'fractal' (or 'long-range-correlated') character of a sequence gradually evaporates, as the frequency of the compositional variations of a simulated sequence continuously increases.

Bacteriophage lambda↗
PubMed1993

Biological origins of long-range correlations and compositional variations in DNA.

The occurrence of certain long-range correlations between nucleotides in DNA sequences of living organisms has recently been reported. The biological origin of these correlations was unknown. The correlations were proposed to be concerned with fractal structure and differences between intron-containing and intron-less sequences. We and others have reported that no consistent difference exists between intron-containing and intron-less sequences. In agreement with this, we demonstrate here that the long-range correlations are trivially equivalent to the varying ratio R between pyrimidines and purines (or any other nucleotide combinations) in different regions of a DNA sequence. Moreover, we show that this variation of R has simple biological explanations: Differences in base composition occur along most DNA sequences and are associated with (i) simple repeats (ii) differences in codon composition (due to the amino acid composition in the encoded protein), (iii) change of the direction of transcription (and thus also translation), and (iv) differences between protein- and rRNA-encoding segments. Seven biological examples are given.

Animals↗