Harmonic maps and constant mean curvature surfaces in \H^2 \times \R

We introduce a hyperbolic Gauss map into the Poincare disk for any surface in H^2xR with regular vertical projection, and prove that if the surface has constant mean curvature H=1/2, this hyperbolic Gauss map is harmonic. Conversely, we show that every nowhere holomorphic harmonic map from an open simply connected Riemann surface into the Poincare disk is the hyperbolic Gauss map of a two-parameter family of such surfaces. As an application we obtain that any holomorphic quadratic differential on the surface can be realized as the Abresch-Rosenberg holomorphic differential of some, and generically infinitely many, complete surfaces with H=1/2 in H^2xR. A similar result applies to minimal surfaces in the Heisenberg group Nil_3. Finally, we classify all complete minimal vertical graphs in H^2xR.Comment: 37 pages, 1 figur

Constant mean curvature surfaces in 3-dimensional Thurston geometries

This is a survey on the global theory of constant mean curvature surfaces in Riemannian homogeneous 3-manifolds. These ambient 3-manifolds include the eight canonical Thurston 3-dimensional geometries, i.e. R3, H3, S3, H2 \times R, S2 \times R, the Heisenberg space Nil3, the universal cover of PSL2(R) and the Lie group Sol3. We will focus on the problems of classifying compact CMC surfaces and entire CMC graphs in these spaces. A collection of important open problems of the theory is also presented

The space of complete embedded maximal surfaces with isolated singularities in the 3-dimensional Lorentz-Minkowski space \l^3

We show that a complete embedded maximal surface in the 3-dimensional Lorentz-Minkowski space $L^3$ with a finite number of singularities is, up to a Lorentzian isometry, an entire graph over any spacelike plane asymptotic to a vertical half catenoid or a horizontal plane and with conelike singular points. We study the space $G_n$ of entire maximal graphs over $\{x_3=0\}$ in $L^3$ with $n+1 \geq 2$ conelike singularities and vertical limit normal vector at infinity. We show that $G_n$ is a real analytic manifold of dimension $3n+4,$ and the coordinates are given by the position of the singular points in $R^3$ and the logarithmic growth at the end. We also introduce the moduli space $M_n$ of {\em marked} graphs with $n+1$ singular points (a mark in a graph is an ordering of its singularities), which is a $(n+1)$-sheeted covering of $G_n.$ We prove that identifying marked graphs differing by translations, rotations about a vertical axis, homotheties or symmetries about a horizontal plane, the corresponding quotient space $M_n$ is an analytic manifold of dimension $3n-1.$Comment: 32 pages, 4 figures, corrected typos, former Theorem 3.3 (now Theorem 2.2) modifie

Bending the Pipeline? Executive Search and Gender Inequality in Hiring for Top Management Jobs

We study the sources of women’s underrepresentation in hiring for top management jobs by focusing on the context of executive search. Using data that include proprietary information on 10,970 individuals considered by a search firm, we examine the sources of the low proportion of women placed in senior roles. Contrary to received wisdom, we find limited evidence that demand-side screeners strongly contribute to gender disadvantage in this setting. What gender differences exist tend to play out at the start of the hiring process and are driven both by supply-side and demand-side actors. Once considered for a position, women are no less likely than men to be hired—though they are slightly less likely to be interviewed by the search firm. Our findings highlight the theoretical importance of disentangling candidates’ “self-steering” behavior from the “pipeline bending” of hiring agents. We discuss the implications of our results for understanding gender inequality at upper echelons of the labor market

Wavelet analysis of the ionospheric response at mid-latitudes during the April 200 storm using magnetograms and vTEC from GPS

In this work we pursue the idea of computing a parameter that allows us to estimate the local ionospheric response to a geospheric event that triggers an ionospheric storm. For that, wavelet technique has been chosen because of its ability to analyze non-stationary signals. The advantage of the time-frequency analysis method called Wavelet Transform resides in providing information not only about the frequencies of the event but also about its location in the time series. Specifically, we compute the Scale Average Wavelet Power (SAWP) of two parameters that describe the local geomagnetic field variation at the Earth surface caused by a geospheric storm and ionospheric response to the storm event. In particular, we propose the time delay between the maximum values of SAWP applied to the vTEC (vertical Total Electron Content) and the horizontal component of the geomagnetic field (H) variations as parameters to characterize the local behavior of the ionospheric storm. We applied the parameter to the geomagnetic and ionospheric disturbances caused by a coronal mass ejection (CME) that took place on April 4, 2000. We used vTEC values computed from GPS observations and H at the surface of the Earth, measured in stations near to each GPS station chosen. The vTEC values used came from the GPS permanent stations belonging to the global IGS (International GNSS Service) network. We chose stations located at magnetic mid-latitudes. Moreover, three-longitude bands representing the ionospheric behavior at different local times (LT) were studied. Because the April 2000 storm has been extensively studied for many authors, the results are compared with those in the literature and we found a very good agreement as expected.En este trabajo perseguimos la idea de estimar un parámetro que nos permita calcular la respuesta ionosférica local a un evento geosférico desencadenante de una tormenta ionosférica. Para ello, se eligió la aplicación de la técnica ondeleta debido a su capacidad para analizar señales no estacionarias. La ventaja del método de análisis en tiempo y frecuencia llamada Transformada Ondeleta reside en el hecho de que provee información, no sólo acerca de las frecuencias del evento, sino también sobre su ubicación en la serie de tiempo. En concreto, se calcula el promedio por escalas de la potencia de la transformada ondeleta (SWAP, de su sigla en inglés Scale Average Wavelet Power) para dos parámetros que describen la respuesta local de la magnetosfera y la ionosfera a una tormenta. En particular, se propone el retraso de tiempo entre los valores máximos de SAWP aplicadas al vTEC (Contenido Electrónico Total en dirección Vertical) y la componente horizontal del campo geomagnético (H), como parámetros cuyas variaciones caracterizan el comportamiento local de la tormenta ionosférica. El parámetro propuesto se aplicó a las perturbaciones geomagnética e ionosférica causadas por una eyección de masa coronal (CME, Coronal Mass Ejection), que tuvo lugar el 4 de abril de 2000. Se utilizaron valores vTEC calculados a partir de las observaciones GPS y H en la superficie de la Tierra, medida en las estaciones cercanas a cada estación de GPS elegida. Los valores de vTEC utilizados provinieron de las estaciones GPS permanentes que pertenecen a la red del servicio internacional IGS (International GNSS Service). Entre todas, elegimos estaciones situadas en latitudes magnéticas medias. Por otra parte, estudiamos tres bandas de longitud que representan el comportamiento de la ionosfera a distintas horas locales (LT). Debido a que la tormenta de abril de 2000 ha sido ampliamente estudiada por muchos autores, los resultados se comparan con los de la literatura y nos encontramos con un muy buen acuerdo entre los datos publicados y nuestros resultados, tal y como se esperaba.Fil: Fernandez, Laura Isabel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Meza, Amalia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Van Zele, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin