Technique for lowering the noise figure in RF amplifiers

Low-level RF amplifiers are operated at noise figures at or near the theoretical minimum, while maintaining high-gain stability. Formulas for the minimum amplifier noise figure value are derived from the analytical noise-figure expression involving the parameters of the equivalent circuit representing the actual system

On the dynamics of social conflicts: looking for the Black Swan

This paper deals with the modeling of social competition, possibly resulting in the onset of extreme conflicts. More precisely, we discuss models describing the interplay between individual competition for wealth distribution that, when coupled with political stances coming from support or opposition to a government, may give rise to strongly self-enhanced effects. The latter may be thought of as the early stages of massive, unpredictable events known as Black Swans, although no analysis of any fully-developed Black Swan is provided here. Our approach makes use of the framework of the kinetic theory for active particles, where nonlinear interactions among subjects are modeled according to game-theoretical tools.Comment: 26 pages, 7 figure

Sums, numbers and infinity:Collections in Bolzano's mathematics and philosophy

This dissertation is a collection of essays almost exclusively focussing on Bernard Bolzano's theory of collections, and its connections to his conception of mathematics. The first significant contribution of this work is that it develops a novel approach for comparing and appraising Bolzano’s collections against the alternatives offered by set theory and mereology. This approach consists in focusing not on the metaphysical comparison but on the role Bolzano's collections play in his mathematics vis à vis the role the sets of set theory (ZFC) play for modern-day mathematics. The second important contribution of this dissertation is a novel interpretation of the interaction between Bolzano's theory of concepts on the one hand, and his way of comparing the size of infinite collections of natural numbers on the other. This culminates in a completely new interpretation of Bolzano's famous Paradoxes of the Infinite as a work that is not an anticipation of Cantorian set theory, but an attempt at deploying philosophical insights on the infinite to develop a sound treatment of infinite series, both converging and diverging ones

What to Fix? Distinguishing between design and non-design rules in automated tools

Technical debt---design shortcuts taken to optimize for delivery speed---is a critical part of long-term software costs. Consequently, automatically detecting technical debt is a high priority for software practitioners. Software quality tool vendors have responded to this need by positioning their tools to detect and manage technical debt. While these tools bundle a number of rules, it is hard for users to understand which rules identify design issues, as opposed to syntactic quality. This is important, since previous studies have revealed the most significant technical debt is related to design issues. Other research has focused on comparing these tools on open source projects, but these comparisons have not looked at whether the rules were relevant to design. We conducted an empirical study using a structured categorization approach, and manually classify 466 software quality rules from three industry tools---CAST, SonarQube, and NDepend. We found that most of these rules were easily labeled as either not design (55%) or design (19%). The remainder (26%) resulted in disagreements among the labelers. Our results are a first step in formalizing a definition of a design rule, in order to support automatic detection.Comment: Long version of accepted short paper at International Conference on Software Architecture 2017 (Gothenburg, SE

Dynamics of Entanglement and Bell-nonlocality for Two Stochastic Qubits with Dipole-Dipole Interaction

We have studied the analytical dynamics of Bell nonlocality as measured by CHSH inequality and entanglement as measured by concurrence for two noisy qubits that have dipole-dipole interaction. The nonlocal entanglement created by the dipole-dipole interaction is found to be protected from sudden death for certain initial states

Classical Evolution of Quantum Elliptic States

The hydrogen atom in weak external fields is a very accurate model for the multiphoton excitation of ultrastable high angular momentum Rydberg states, a process which classical mechanics describes with astonishing precision. In this paper we show that the simplest treatment of the intramanifold dynamics of a hydrogenic electron in external fields is based on the elliptic states of the hydrogen atom, i.e., the coherent states of SO(4), which is the dynamical symmetry group of the Kepler problem. Moreover, we also show that classical perturbation theory yields the {\it exact} evolution in time of these quantum states, and so we explain the surprising match between purely classical perturbative calculations and experiments. Finally, as a first application, we propose a fast method for the excitation of circular states; these are ultrastable hydrogenic eigenstates which have maximum total angular momentum and also maximum projection of the angular momentum along a fixed direction. %Comment: 8 Pages, 2 Figures. Accepted for publication in Phys. Rev.

Entanglement degradation in the solid state: interplay of adiabatic and quantum noise

We study entanglement degradation of two non-interacting qubits subject to independent baths with broadband spectra typical of solid state nanodevices. We obtain the analytic form of the concurrence in the presence of adiabatic noise for classes of entangled initial states presently achievable in experiments. We find that adiabatic (low frequency) noise affects entanglement reduction analogously to pure dephasing noise. Due to quantum (high frequency) noise, entanglement is totally lost in a state-dependent finite time. The possibility to implement on-chip both local and entangling operations is briefly discussed.Comment: Replaced with published version. Minor change

Derivation of new chemotaxis models by asymptotic analysis of kinetic models for large binary cell mixtures

This paper deals with the derivation of macroscopic tissue models from the underlying description delivered by a class of equations modeling, by methods of the kinetic theory, binary mixtures of multi-cellular systems. The analysis refers to a suitable parabolic approximation to show how the macroscopic tissue behavior can be described from the underlying cellular description. The approach is specifically focused on the modeling of classical chemotaxis phenomena, and the chemotaxis–flui

Hemofiltration in sepsis: where do we go from here?

Hemofiltration as an adjunct to therapy for sepsis is now 10 years old. Despite early successes and significant theoretical advantages, the treatment remains experimental. Although feasibility has been established, efficacy has proved to be much more difficult. Clinical as well as technical difficulties remain important considerations to future studies. These issues are discussed and the brief history of hemofiltration in sepsis is reviewed