Suppression laws for multi-particle interference in Sylvester interferometers

Quantum interference of correlated particles is a fundamental quantum phenomenon which carries signatures of the statistics properties of the particles, such as bunching or anti-bunching. In presence of particular symmetries, interference effects take place with high visibility, one of the simplest cases being the suppression of coincident detection in the Hong-Ou-Mandel effect. Tichy et al. recently demonstrated a simple sufficient criterion for the suppression of output events in the more general case of Fourier multi-port beam splitters. Here we study the case in which $2^q$ particles (either bosonic or fermionic) are injected simultaneously in different ports of a Sylvester interferometer with $2^p \geq 2^q$ modes. In particular, we prove a necessary and sufficient criterion for a significant fraction of output states to be suppressed, for specific input configurations. This may find application in assessing the indistinguishability of multiple single photon sources and in the validation of boson sampling machines

Michel Hockx. A snowy morning : eight Chinese poets on the road to modernity

This article reviews the book A Snowy Morning: Eight Chinese Poets on the Road to Modernity , written by Michel Hockx

Serotonin, how to find it...

Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system (CNS) of animals, including humans. Discovered and crystallized over sixty years ago, serotonin operates as a short-range neurotransmitter as well as a long-range signalling modulator, with multiple effects on whole organism functions via plasma, platelet and neuroendocrine, gut, adrenal and other peripheral systems across many species. All of the important functions of serotonin in the brain and body were identified over the ensuing years by neurochemical, physiological and pharmacological investigations. Mainly, all these investigations have been performed via invasive methodologies, particularly in the CNS studies. Here we present a rapid overview of such methodological approaches focussing on voltammetry, one of the most recent technical approaches for serotonin analysis in vivo, in situ and in real time. Furthermore, we introduce a late technical evolution in the attempt to obtain in vivo non invasive measurement of brain serotonin.peer-reviewe

Land Use Law in New York State: Playing Hide & SEQRA with the Elusive Comprehensive Plan

In this comment, the author discusses comprehensive planning and land-use regulation in New York, and SEQRA\u27s role and influence in the planning and land-use decision making process. In addition to discussing SEQRA\u27s positive influence in bringing environmental issues into the forefront, the author focuses on the potential use of SEQRA\u27s procedural devices as a substitute for formal comprehensive planning, and the possible dangers which may result. The author suggests how SEQRA would best serve the planning process and proposes that mandatory planning be required from local to regional levels

Productivity And Firm Heterogeneity In Chile

We analyze productivity growth in Chilean manufacturing 1979-2000 using the newly available panel of establishments drawn from the Census of Manufacturing. We examine the contribution to productivity growth of ?internal? restructuring (such as new technology and organizational change among survivors) and ?external? restructuring (exit, entry and market share change). We find that (a) ?external restructuring? accounts for 52% of industry labour productivity growth and 57% of industry TFP growth; (b) much of the external restructuring effect comes from the closing down of poorly-performing plants due to import penetration, and (c) import penetration is also an important determinant of internal restructuring in the long term.Productivity, TFP, Firm, Chile

Notes on the Determinants of Innovation: A Multi-Perspective Analysis

The study of innovation and technological change is an increasing field of economic enquire because innovation can be considered a major engine of growth. This paper is concerned with the determinants of innovation and technological change. Different theoretical approaches present in the literature are systematically considered. The aim of this work is to offer an overview of contributions emerging from different perspectives trying to place them in their proper theoretical framework. The paper will be divided in different subsections in which each determinant is individually treated through the presentation of the most relevant results achieved by the literature on the specific issue. Policy considerations and hints for further research are also provided.Determinants of innovation, Innovation and knowledge, National systems of innovation, Intellectual property rights, Technology policy

Algebraic properties of structured context-free languages: old approaches and novel developments

The historical research line on the algebraic properties of structured CF languages initiated by McNaughton's Parenthesis Languages has recently attracted much renewed interest with the Balanced Languages, the Visibly Pushdown Automata languages (VPDA), the Synchronized Languages, and the Height-deterministic ones. Such families preserve to a varying degree the basic algebraic properties of Regular languages: boolean closure, closure under reversal, under concatenation, and Kleene star. We prove that the VPDA family is strictly contained within the Floyd Grammars (FG) family historically known as operator precedence. Languages over the same precedence matrix are known to be closed under boolean operations, and are recognized by a machine whose pop or push operations on the stack are purely determined by terminal letters. We characterize VPDA's as the subclass of FG having a peculiarly structured set of precedence relations, and balanced grammars as a further restricted case. The non-counting invariance property of FG has a direct implication for VPDA too.Comment: Extended version of paper presented at WORDS2009, Salerno,Italy, September 200

GENERIC COMMODITY PROMOTION AND PRODUCT DIFFERENTIATION

This paper considers whether generic promotion lowers the differentiation among competing brands as claimed in the 1997 Supreme Court case (Wileman et al. v. Glickman). Commodity promotion is modeled as a multi-stage game where products are vertically differentiated. Analytical results show that if the benefits of generic advertising from increased demand are outweighed by the costs from lower product differentiation then high-quality producers will not benefit from generic promotion but producers of lower-quality goods may.generic advertising, product differentiation, spatial model, Marketing,

Higher-Order Operator Precedence Languages

Floyd's Operator Precedence (OP) languages are a deterministic context-free family having many desirable properties. They are locally and parallely parsable, and languages having a compatible structure are closed under Boolean operations, concatenation and star; they properly include the family of Visibly Pushdown (or Input Driven) languages. OP languages are based on three relations between any two consecutive terminal symbols, which assign syntax structure to words. We extend such relations to k-tuples of consecutive terminal symbols, by using the model of strictly locally testable regular languages of order k at least 3. The new corresponding class of Higher-order Operator Precedence languages (HOP) properly includes the OP languages, and it is still included in the deterministic (also in reverse) context free family. We prove Boolean closure for each subfamily of structurally compatible HOP languages. In each subfamily, the top language is called max-language. We show that such languages are defined by a simple cancellation rule and we prove several properties, in particular that max-languages make an infinite hierarchy ordered by parameter k. HOP languages are a candidate for replacing OP languages in the various applications where they have have been successful though sometimes too restrictive.Comment: In Proceedings AFL 2017, arXiv:1708.0622