Search results for "J3"

Heritability of Lifetime Income

2013

Using 15 years of data on Finnish twins, we find that 24% (54%) of the variance of women’s (men’s) lifetime income is due to genetic factors and that the contribution of the shared environment is negligible. We link these figures to policy by showing that controlling for education reduces the variance share of genetics by 5-8 percentage points; by demonstrating that income uncertainty has a genetic component half the size of its variance share in lifetime income; and by exploring how the genetic heritability of lifetime income is related to the macroeconomic environment, as measured by GDP growth and the Gini-coefficient of income inequality.

Infinitesimal deformations of double covers of smooth algebraic varieties

2003

The goal of this paper is to give a method to compute the space of infinitesimal deformations of a double cover of a smooth algebraic variety. The space of all infinitesimal deformations has a representation as a direct sum of two subspaces. One is isomorphic to the space of simultaneous deformations of the branch locus and the base of the double covering. The second summand is the subspace of deformations of the double covering which induce trivial deformations of the branch divisor. The main result of the paper is a description of the effect of imposing singularities in the branch locus. As a special case we study deformations of Calabi--Yau threefolds which are non--singular models of do…

New fourfolds from F-theory

2015

In this paper, we apply Borcea-Voisin's construction and give new examples of fourfolds containing a del Pezzo surface of degree six, which admit an elliptic fibration on a smooth threefold. Some of these fourfolds are Calabi-Yau varieties, which are relevant for the $N=1$ compactification of Type IIB string theory known as $F$-Theory. As a by-product, we provide a new example of a Calabi--Yau threefold with Hodge numbers $h^{1,1}=h^{2,1}=10$.

On First-Passage-Time Densities for Certain Symmetric Markov Chains

2004

The spatial symmetry property of truncated birth-death processes studied in Di Crescenzo [6] is extended to a wider family of continuous-time Markov chains. We show that it yields simple expressions for first-passage-time densities and avoiding transition probabilities, and apply it to a bilateral birth-death process with jumps. It is finally proved that this symmetry property is preserved within the family of strongly similar Markov chains.

Complex multiplication, Griffiths-Yukawa couplings, and rigidity for families of hypersurfaces

2003

Let M(d,n) be the moduli stack of hypersurfaces of degree d > n in the complex projective n-space, and let M(d,n;1) be the sub-stack, parameterizing hypersurfaces obtained as a d fold cyclic covering of the projective n-1 space, ramified over a hypersurface of degree d. Iterating this construction, one obtains M(d,n;r). We show that M(d,n;1) is rigid in M(d,n), although the Griffiths-Yukawa coupling degenerates for d<2n. On the other hand, for all d>n the sub-stack M(d,n;2) deforms. We calculate the exact length of the Griffiths-Yukawa coupling over M(d,n;r), and we construct a 4-dimensional family of quintic hypersurfaces, and a dense set of points in the base, where the fibres ha…

A double mean field equation related to a curvature prescription problem

2019

We study a double mean field-type PDE related to a prescribed curvature problem on compacts surfaces with boundary. We provide a general blow-up analysis, then a Moser-Trudinger inequality, which gives energy-minimizing solutions for some range of parameters. Finally, we provide existence of min-max solutions for a wider range of parameters, which is dense in the plane if $��$ is not simply connected.

Integrability of the one dimensional Schrödinger equation

2018

We present a definition of integrability for the one dimensional Schroedinger equation, which encompasses all known integrable systems, i.e. systems for which the spectrum can be explicitly computed. For this, we introduce the class of rigid functions, built as Liouvillian functions, but containing all solutions of rigid differential operators in the sense of Katz, and a notion of natural boundary conditions. We then make a complete classification of rational integrable potentials. Many new integrable cases are found, some of them physically interesting.

A Mountain Pass Theorem for a Suitable Class of Functions

2009

Graduate employment and the returns to higher education in Africa

2013

http://cemapre.iseg.utl.pt/educonf/2e3/files/submissions_to_web/Barounia%20Mahdi_Broeckeb%20%20Stijn.docx; In this paper, we estimate the return to higher education for 12 African countries using recent data and a variety of methods. Importantly, one of our methods adjusts for the effect of higher education on the rate of joblessness, which is substantial in most African countries, and particularly for women. Our results confirm that Mincerian coefficients cannot be interpreted as a true rate of return, and that the latter (even after taking into account the employment effect) is considerably lower than what has previously been suggested in the literature (less than half). For Sub-Saharan A…

Macroeconomic Impact of Pension System Upon Private Pension Funds Scheme. Empirical Evidence from Central and Eastern European Countries

2021

Abstract The significance of retirement savings and private pension funds increased in the latest decades and gathered important amounts of capitals. The purpose of this paper is to investigate the macroeconomic effects of pension systems from an investment perspective in five Central and Eastern European countries. The analyzing process regarding several underlying macroeconomic effects of pension systems started from the premises that there is a strong connection between the structure of pension systems, the national economy and the development of the financial sector. The econometric tests were processed and applied by using pool data regression models and the method Pooled Instrumental …