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The origin of chert in the Aurignacian of Vogelherd Cave investigated by infrared spectroscopy.

ABSTRACT: The analyses of raw material provenance offers the possibility of tracing short and long-distance raw material transport. So far, most studies of raw material of flint and chert in Europe have been based on macroscopic analyses. We apply infrared spectroscopy to Aurignacian assemblages from Vogelherd cave and to the Magdalenian site Randecker Maar in southwestern Germany. We compare raw material samples from three chert-bearing areas in Germany with archaeological samples from Vogelherd. Our results show that infrared spectroscopy can distinguish between different raw materials. Our archaeological samples from Vogelherd correspond to the sampled geological cherts in terms of their spectral signature. Our comparison of reference samples and archaeological samples highlights problems in commonly used macroscopic identifications of chert raw materials.

SUBMITTER: Schurch B

PROVIDER: S-EPMC9385009 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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The origin of chert in the Aurignacian of Vogelherd Cave investigated by infrared spectroscopy.

Schürch Benjamin B Wettengl Stefan S Fröhle Simon S Conard Nicholas N Schmidt Patrick P

PloS one 20220817 8

The analyses of raw material provenance offers the possibility of tracing short and long-distance raw material transport. So far, most studies of raw material of flint and chert in Europe have been based on macroscopic analyses. We apply infrared spectroscopy to Aurignacian assemblages from Vogelherd cave and to the Magdalenian site Randecker Maar in southwestern Germany. We compare raw material samples from three chert-bearing areas in Germany with archaeological samples from Vogelherd. Our res ...[more]

PMID: 35976960

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Project description:We have studied the structure of (Ala)5, a model unfolded peptide, using a combination of 2D IR spectroscopy and molecular dynamics (MD) simulation. Two different isotopomers, each bis-labeled with (13)C═O and (13)C═(18)O, were strategically designed to shift individual site frequencies and uncouple neighboring amide-I' modes. 2D IR spectra taken under the double-crossed ⟨π/4, -π/4, Y, Z⟩ polarization show that the labeled four-oscillator systems can be approximated by three two-oscillator systems. By utilizing the different polarization dependence of diagonal and cross peaks, we extracted the coupling constants and angles between three pairs of amide-I' transition dipoles through spectral fitting. These parameters were related to the peptide backbone dihedral angles through DFT calculated maps. The derived dihedral angles are all located in the polyproline-II (ppII) region of the Ramachandran plot. These results were compared to the conformations sampled by Hamiltonian replica-exchange MD simulations with three different CHARMM force fields. The C36 force field predicted that ppII is the dominant conformation, consistent with the experimental findings, whereas C22/CMAP predicted similar population for α+, β, and ppII, and the polarizable Drude-2013 predicted dominating β structure. Spectral simulation based on MD representative conformations and structure ensembles demonstrated the need to include multiple 2D spectral features, especially the cross-peak intensity ratio and shape, in structure determination. Using 2D reference spectra defined by the C36 structure ensemble, the best spectral simulation is achieved with nearly 100% ppII population, although the agreement with the experimental cross-peak intensity ratio is still insufficient. The dependence of population determination on the choice of reference structures/spectra and the current limitations on theoretical modeling relating peptide structures to spectral parameters are discussed. Compared with the previous results on alanine based oligopeptides, the dihedral angles of our fitted structure, and the most populated ppII structure from the C36 simulation are in good agreement with those suggesting a major ppII population. Our results provide further support for the importance of ppII conformation in the ensemble of unfolded peptides.

Project description:The present study aimed to investigate the effects of degraded speech perception and binaural unmasking using functional near-infrared spectroscopy (fNIRS). Normal hearing listeners were tested when attending to unprocessed or vocoded speech, presented to the left ear at two speech-to-noise ratios (SNRs). Additionally, by comparing monaural versus diotic masker noise, we measured binaural unmasking. Our primary research question was whether the prefrontal cortex and temporal cortex responded differently to varying listening configurations. Our a priori regions of interest (ROIs) were located at the left dorsolateral prefrontal cortex (DLPFC) and auditory cortex (AC). The left DLPFC has been reported to be involved in attentional processes when listening to degraded speech and in spatial hearing processing, while the AC has been reported to be sensitive to speech intelligibility. Comparisons of cortical activity between these two ROIs revealed significantly different fNIRS response patterns. Further, we showed a significant and positive correlation between self-reported task difficulty levels and fNIRS responses in the DLPFC, with a negative but non-significant correlation for the left AC, suggesting that the two ROIs played different roles in effortful speech perception. Our secondary question was whether activity within three sub-regions of the lateral PFC (LPFC) including the DLPFC was differentially affected by varying speech-noise configurations. We found significant effects of spectral degradation and SNR, and significant differences in fNIRS response amplitudes between the three regions, but no significant interaction between ROI and speech type, or between ROI and SNR. When attending to speech with monaural and diotic noises, participants reported the latter conditions being easier; however, no significant main effect of masker condition on cortical activity was observed. For cortical responses in the LPFC, a significant interaction between SNR and masker condition was observed. These findings suggest that binaural unmasking affects cortical activity through improving speech reception threshold in noise, rather than by reducing effort exerted.

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The origin of chert in the Aurignacian of Vogelherd Cave investigated by infrared spectroscopy.

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The origin of chert in the Aurignacian of Vogelherd Cave investigated by infrared spectroscopy.

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