Representative Democracy and Marginal Rate Progressive Income Taxation

This paper develops a political economy model that is consistent with the fact that democracies have a preference for increasing marginal tax rates on income. We present a model in which there is an exogenous set of political parties with preferences over the set of admissible tax schedules. This set contains virtually any increasing and piecewise linear continuous function. Each party decides whether or not to present a candidate for election. There is a fixed cost of running. The elected candidate implements one of her preferred tax policies. Our main results provide conditions under which a Strong Nash Equilibrium exists, and a tax schedule with increasing marginal tax rates is implemented in some Nash Equilibria and in any Strong Nash Equilibrium.REPRESENTATIVE DEMOCRACY; MARGINAL RATE PROGRESSIVE INCOME TAXATION.

On the possibility of generating a 4-neutron resonance with a {\boldmath T=3/2T=3/2} isospin 3-neutron force

We consider the theoretical possibility to generate a narrow resonance in the four neutron system as suggested by a recent experimental result. To that end, a phenomenological $T=3/2$ three neutron force is introduced, in addition to a realistic $NN$ interaction. We inquire what should be the strength of the $3n$ force in order to generate such a resonance. The reliability of the three-neutron force in the $T=3/2$ channel is exmined, by analyzing its consistency with the low-lying $T=1$ states of $^4$H, $^4$He and $^4$Li and the $^3{\rm H} + n$ scattering. The {\it ab initio} solution of the $4n$ Schr\"{o}dinger equation is obtained using the complex scaling method with boundary conditions appropiate to the four-body resonances. We find that in order to generate narrow $4n$ resonant states a remarkably attractive $3N$ force in the $T=3/2$ channel is required.Comment: 11 pages, 11 figures, minor change, published version, to be published in Physical Review

Aligator.jl - A Julia Package for Loop Invariant Generation

We describe the Aligator.jl software package for automatically generating all polynomial invariants of the rich class of extended P-solvable loops with nested conditionals. Aligator.jl is written in the programming language Julia and is open-source. Aligator.jl transforms program loops into a system of algebraic recurrences and implements techniques from symbolic computation to solve recurrences, derive closed form solutions of loop variables and infer the ideal of polynomial invariants by variable elimination based on Gr\"obner basis computation

“In a newe plantation it is not knowen whether man or woman be more necessary”: Gender Relations in Seventeenth-Century Virginia

The historical narrative of colonial Virginia has traditionally been that of a testosterone-fueled society of aggressive men competing to make a profit from tobacco. Accounts of seventeenth-century Virginia rarely include references to female settlers, and those that do merely mention the skewed gender ratio during the first century. However, a female presence was critical to Virginia’s transition from economic outpost to settlement. Although their numbers were limited, women played essential roles in the social fabric of early Virginia society. Men on both sides of the Atlantic believed that there was a direct correlation between women’s behavior and the future stability of the colony. In their efforts to establish patriarchal order within the colony, men strictly regulated women’s actions. In an environment that lacked many of the traditional English social, religious and political structures, gender roles appeared surprisingly analogous to those in England. However, differences in Virginia’s institutional development such as the system of indentured servitude and the high mortality rates influenced the emergence of new patterns of gendered interactions. This thesis explores the question of Virginian exceptionalism by looking at gender in an attempt to understand the extent to which a distinctive environment in Virginia led to similarly distinct gender norms. Using court records and early legislation, I examine women in their conventional positions as servants, wives, and widows and highlight the ways that women violated these norms

Antiproton-deuteron annihilation at low energies

Recent experimental studies of the antiproton-deuteron system at low energies have shown that the imaginary part of the antiproton-deuteron scattering length is smaller than the antiproton-proton one. Two- and three-body systems with strong annihilation are investigated and a mechanism explaining this unexpected relation between the imaginary parts of the scattering lengths is proposed.Comment: 6 pages, 3 figures, to be published in The European Physical Journal

Generating all polynomial invariants in simple loops

AbstractThis paper presents a method for automatically generating all polynomial invariants in simple loops. It is first shown that the set of polynomials serving as loop invariants has the algebraic structure of an ideal. Based on this connection, a fixpoint procedure using operations on ideals and Gröbner basis constructions is proposed for finding all polynomial invariants. Most importantly, it is proved that the procedure terminates in at most m+1 iterations, where m is the number of program variables. The proof relies on showing that the irreducible components of the varieties associated with the ideals generated by the procedure either remain the same or increase their dimension at every iteration of the fixpoint procedure. This yields a correct and complete algorithm for inferring conjunctions of polynomial equalities as invariants. The method has been implemented in Maple using the Groebner package. The implementation has been used to automatically discover non-trivial invariants for several examples to illustrate the power of the technique

Artificial Small RNA-Based Silencing Tools for Antiviral Resistance in Plants

[EN] Artificial small RNAs (art-sRNAs), such as artificial microRNAs (amiRNAs) and synthetic trans-acting small interfering RNAs (syn-tasiRNAs), are highly specific 21-nucleotide small RNAs designed to recognize and silence complementary target RNAs. Art-sRNAs are extensively used in gene function studies or for improving crops, particularly to protect plants against viruses. Typically, antiviral art-sRNAs are computationally designed to target one or multiple sites in viral RNAs with high specificity, and art-sRNA constructs are generated and introduced into plants that are subsequently challenged with the target virus(es). Numerous studies have reported the successful application of art-sRNAs to induce resistance against a large number of RNA and DNA viruses in model and crop species. However, the application of art-sRNAs as an antiviral tool has limitations, such as the difficulty to predict the efficacy of a particular art-sRNA or the emergence of virus variants with mutated target sites escaping to art-sRNA-mediated degradation. Here, we review the different classes, features, and uses of art-sRNA-based tools to induce antiviral resistance in plants. We also provide strategies for the rational design of antiviral art-sRNAs and discuss the latest advances in developing art-sRNA-based methodologies for enhanced resistance to plant viruses.This research was funded by grants RYC-2017-21648 and RTI2018-095118-A-100 from the Ministerio de Ciencia, Innovacion y Universidades (MCIU, Spain), Agencia Estatal de Investigacion (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, European Union) to AC.Cisneros, AE.; Carbonell, A. (2020). Artificial Small RNA-Based Silencing Tools for Antiviral Resistance in Plants. Plants. 9(6):1-16. https://doi.org/10.3390/plants9060669S1169