Abstract:The conformational preferences of the alicyclic C","-disubstituted glycines Ac,c (I-amino-I-cycloalkane-carboxylic acid; n = 4 , 7, 9, 1 2 ) were assessed in selected model compounds, including homopeptides and Ala (or Aib, a-aminoisobutyric acid) lAc,c peptides containing a small total number of residues, by Fourier transform ir absorption, 'H-nmr, and x-ray diffraction analyses. The results obtained indicate that p-turn and 310-helicalstructures are preferentially adopted by short peptides rich in these cycloaliphatic a-amino acids.

1 In-region location verification (IRLV) aims at verifying whether a user is inside a region of interest (ROI). In wireless networks, IRLV can exploit the features of the channel between the user and a set of trusted access points. In practice, the channel feature statistics is not available and we resort to machine learning (ML) solutions for IRLV. We first show that solutions based on either neural networks (NNs) or support vector machines (SVMs) and typical loss functions are Neyman-Pearson (N-P)-optimal at learning convergence for sufficiently complex learning machines and large training datasets . Indeed, for finite training, ML solutions are more accurate than the N-P test based on estimated channel statistics.Then, as estimating channel features outside the ROI may be difficult, we consider one-class classifiers, namely auto-encoders NNs and one-class SVMs, which however are not equivalent to the generalized likelihood ratio test (GLRT), typically replacing the N-P test in the one-class problem. Numerical results support the results in realistic wireless networks, with channel models including path-loss, shadowing, and fading. Index TermsAuto-encoder, in-region location verification, machine learning, neural network, support vector machine.

The preferred conformations of C"-methyl phenylglycine, C"-methyl phenylalanine, and C"-methyl homophenylalanine residues, as determined in model peptides (including homopeptides) by Fourier transform ir absorption, 'H-nmr, CD, and x-ray diffraction techniques

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