Diversity in Parametric Families of Number Fields

Let X be a projective curve defined over Q and t a non-constant Q-rational function on X of degree at least 2. For every integer n pick a point P_n on X such that t(P_n)=n. A result of Dvornicich and Zannier implies that, for large N, among the number fields Q(P_1),...,Q(P_N) there are at least cN/\log N distinct, where c>0. We prove that there are at least N/(\log N)^{1-c} distinct fields, where c>0.Comment: Minor inaccuracies detected by the referees are correcte

The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects

We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides and peptide synthesis. TOAC was the first spin label probe incorporated in peptides by means of a peptide bond. In view of the rigid character of this cyclic molecule and its attachment to the peptide backbone via a peptide bond, TOAC incorporation has been very useful to analyze backbone dynamics and peptide secondary structure. Many of these studies were performed making use of EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, and FT-IR, have been employed. The use of double-labeled synthetic peptides has allowed the investigation of their secondary structure. A large number of studies have focused on the interaction of peptides, both synthetic and biologically active, with membranes. In the latter case, work has been reported on ligands and fragments of GPCR, host defense peptides, phospholamban, and β-amyloid. EPR studies of macroscopically aligned samples have provided information on the orientation of peptides in membranes. More recent studies have focused on peptide–protein and peptide–nucleic acid interactions. Moreover, TOAC has been shown to be a valuable probe for paramagnetic relaxation enhancement NMR studies of the interaction of labeled peptides with proteins. The growth of the number of TOAC-related publications suggests that this unnatural amino acid will find increasing applications in the future

Implementation of Two-Mode Gaussian States Whose Covariance Matrix Has the Standard Form

This paper deals with the covariance matrix (CM) of two-mode Gaussian states, which, together with the mean vector, fully describes these states. In the two-mode states, the (ordinary) CM is a real symmetric matrix of order 4; therefore, it depends on 10 real variables. However, there is a very efficient representation of the CM called the standard form (SF) that reduces the degrees of freedom to four real variables, while preserving all the relevant information on the state. The SF can be easily evaluated using a set of symplectic invariants. The paper starts from the SF, introducing an architecture that implements with primitive components the given two-mode Gaussian state having the CM with the SF. The architecture consists of a beam splitter, followed by the parallel set of two single-mode real squeezers, followed by another beam splitter. The advantage of this architecture is that it gives a precise non-redundant physical meaning of the generation of the Gaussian state. Essentially, all the relevant information is contained in this simple architecture

DSP Implementation of Packet Synchronization for OFDM

This work presents the packet synchronization in the baseband implementation of an OFDM system on a DSP board. The basic system blocks, following the design parameters of the HIPERLAN/2 standard, have been implemented. This work focuses on the packet synchronization aspects, presenting some results in terms of the packet loss probability determined by a wrong synchronization. The implementation has been tested on a Texas Instruments C64 fixed-point DSP and is part of a more general project to achieve the implementation of a OFDM transmission system, up to an IF analog output, using high speed ADCs and DACs

Sarcopenia: looking to muscle mass to better manage pancreatic cancer patients

4nonenoneBasile D.; Corvaja C.; Caccialanza R.; Aprile G.Basile, D.; Corvaja, C.; Caccialanza, R.; Aprile, G

Instantaneous wideband channel sounding for 1.7 GHz PCS

This paper presents the technique for channel sounding experiments carried out at the Hewlett-Packard Laboratories in Bristol. The channel sounding measurements were taken at 1.7225 GHz, a frequency similar to those used by DCS 1800 and DECT, and to those which will be employed by other emerging PCS standards. Due to the time-varying characteristics of these radio channels, it is important to reflect the variations of the channel impulse response in the experiments, since the average impulse response gives only limited information for the analysis of radio communication systems. The technique presented is based on a software correlation between the input and the output of the channel, and the dynamic performance achieved is better than that obtained with conventional techniques. In particular, unlike conventional correlation sounders, this technique does not suffer from the trade-off between dynamic range and maximum resolvable Doppler shif

Diversity in Parametric Families of Number Fields

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