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On the boundary behavior of the holomorphic sectional curvature of the Bergman metric
Elisabetta Barletta
Le Matematiche , 2006,
Abstract: We obtain a conceptually new differential geometric proof of P. F. Klembeck’s result (cf. [9]) that the holomorphic sectional curvature k g (z ) of the Bergman metric of a strictly pseudoconvex domain Ω n approaches 4/(n + 1) (the constant sectional curvature of the Bergman metric of the unit ball) as z → Ω.
Masochistic Ritual and Rebirth in Fern o Mendes Pinto’s Peregrina o
Barletta, Vincent
Ellipsis , 2009,
Abstract: The present study examines the ontogenetically productive role of humiliation and violence within Fern o Mendes Pinto’s (1509?-1583) Peregrina o, a canonical work of the Portuguese Renaissance. Explicitly adapting Gilles Deleuze’s reading of the work of Leopold von Sacher-Masoch (Coldness and Cruelty) to the Peregrina o, this study engages in a focused analysis of masochistic rituals encoded within Mendes Pinto’s narrative. Focusing on two specific episodes in the text, both of them ritual murders – one carried out by Portuguese captains in the Red Sea and another by Southeast Asians in the Kingdom of Pegu – this study explores the ways in which the Peregrina o employs the logic of the masochistic contract, and the rituals that sustain it, in strategic ways.
Comparative study of Rare Gas-H$_2$ triatomic complexes
Paolo Barletta
Physics , 2008, DOI: 10.1140/epjd/e2009-00058-0
Abstract: This paper presents a comparative analysis of complexes made of one Rare Gas (Rg) atom and molecular hydrogen, for all five stable Rg atoms. In particular, the vibrational band origins have been calculated, as well as the structural properties of the associated wavefunctions. The study is extended to cold Rg-H$_2$ scattering. The molecular systems are studied variationally using a very simple, yet effective, trial wavefunction. A large number of Potential Energy Surfaces available from the literature is considered. A comparative analysis shows that differences of up to two orders of magnitude exist for the zero energy elastic cross sections of the five complexes. Corrections to the model have also been considered, showing no significant effect.
Local energy balance, specific heats and the Oberbeck-Boussinesq approximation
A. Barletta
Physics , 2009, DOI: 10.1016/j.ijheatmasstransfer.2009.06.006
Abstract: A thermodynamic argument is proposed in order to discuss the most appropriate form of the local energy balance equation within the Oberbeck-Boussinesq approximation. The study is devoted to establish the correct thermodynamic property to be used in order to express the relationship between the change of internal energy and the temperature change. It is noted that, if the fluid is a perfect gas, this property must be identified with the specific heat at constant volume. If the fluid is a liquid, a definitely reliable approximation identifies this thermodynamic property with the specific heat at constant pressure. No explicit pressure work term must be present in the energy balance. The reasoning is extended to the case of fluid saturated porous media.
An Introduction to Quantum Mechanics ... for those who dwell in the macroscopic world
Antonio Barletta
Physics , 2012,
Abstract: There is a huge number of excellent and comprehensive textbooks on quantum mechanics. They mainly differ for the approach, more or less oriented to the formalism rather than to the phenomenology, as well as for the topics covered. These lectures have been based mainly on the classical textbook by Gasiorowicz (1974). I must confess that the main reason for my choice of Gasiorowicz (1974) is affective, as it was the textbook were I first learned the basic principles of quantum mechanics. Beyond my personal taste, I now recognize that Gasiorowicz (1974) is still a very good textbook on quantum mechanics, with a rigorous theoretical approach accompanied by a wide collection of applications. If the textbook by Gasiorowicz was my main basis, I have taken much also from other textbooks such as Phillips (2003), as well as from the excellent classical textbook by Dirac (1981).
On the pseudohermitian sectional curvature of a strictly pseudoconvex CR manifold
Elisabetta Barletta
Mathematics , 2006,
Abstract: We study the pseudohermitian sectional curvature of a CR manifold.
The Lichnerowicz theorem on CR manifolds
Elisabetta Barletta
Mathematics , 2006,
Abstract: We obtain a Bochner type formula and an estimate from below on the spectrum of the sublaplacian of a compact strictly pseudoconvex CR manifold.
On the boundary behavior of the holomorphic sectional curvature of the Bergman metric
Elisabetta Barletta
Mathematics , 2006,
Abstract: We obtain a conceptually new differential geometric proof of P.F. Klembeck's result that the holomorphic sectional curvature of a strictly pseudoconvex domain approaches (in the boundary limit) the constant sectional curvature of the Bergman metric of the unit ball.
Design of Short, High-Rate DVB-S2-Like Semi-Regular LDPC Codes
Luca Barletta,Arnaldo Spalvieri
Journal of Electrical and Computer Engineering , 2008, DOI: 10.1155/2008/324503
Abstract: This work focuses on high-rate (>4/5) moderate-length (1000≤<5000) low-density parity-check codes. High-rate codes allow to maintain good quality of the preliminary decisions that are used in carrier recovery, while a moderate code length allows to keep the latency low. The interleaver of the LDPC matrix that we consider is inspired to the DVB-S2 standard one. A novel approach for avoiding short cycles is analyzed. A modified BP decoding algorithm is applied in order to deal with longer cycles. Simulations and results for the AWGN channel are presented, both for BPSK signalling and for coded modulation based on the partition ?2/4?2.
Optimal Filtering in Pilot-Aided Carrier Recovery
Arnaldo Spalvieri,Luca Barletta
Journal of Electrical and Computer Engineering , 2009, DOI: 10.1155/2009/645615
Abstract: The paper deals with carrier recovery based on pilot symbols in single-carrier systems. Wiener's method is used to determine the optimal unconstrained filter in estimation of phase noise assuming that a sequence of equally spaced pilot symbols is available. Our analysis allows to capture two effects that are not considered in the existing literature: the impact of aliasing due to sampling of the phase noise sequence at the pilot rate and the cyclostationary nature of the estimate hence of its performance. Experimental results are derived also for the case, where the filter is constrained to the cascade of two moving averages. These results show that, in the considered example, the mean-square phase error of the constrained filter is within 0.35?dB from the MSE of the optimal filter. 1. Introduction The performance of single-carrier microwave radio systems operating at high spectral efficiency is often limited by the phase noise introduced by local oscillators that generate the sinusoid used for up/down-conversion. As the number of constellation points grows, the S-curve of the conventional decision-directed phase detector used in carrier recovery based on phase-locked loop becomes narrow and narrow. As a consequence, the receiver becomes less and less able to recover the phase noise that affects the incoming carrier, up to the appearance of the phenomenon of cycle slip, that definitively degrades performance. To overcome this limit, pilot symbols can be periodically introduced in the data sequence to improve the robustness of the receiver in estimating the carrier phase, as proposed in [1] for synchronous transmission systems. In [2] the influence of the pilot pattern in burst transmission is investigated. Pilot symbols have proven their usefulness also in iterative joint decoding and synchronization [3, 4]. In the present paper, we consider the optimization of the filter that produces the phase estimate at symbol rate from the noisy observation of the phase noise at pilot rate. One crucial point in pilot-aided carrier recovery is the design of the pilot rate. The pilot rate should be kept as small as possible to maintain low the overhead due to the pilot symbols. However, a too small pilot rate induces substantial aliasing in the sequence of sampled phase noise, compromising the performance of carrier recovery. The novelty of the present contribution is the consideration of aliasing in the design of the carrier recovery mechanism and in the evaluation of its performance. The paper is organized as follows. In Section 2 the system model is introduced,
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