Mechanisms producing different precipitation patterns over north‐eastern Italy: insights from HyMeX‐SOP1 and previous events

During the first HyMeX Special Observation Period (SOP1) field campaign, the target site of north‐eastern Italy (NEI) experienced a large amount of precipitation, locally exceeding the climatological values and distributed among several heavy‐rainfall episodes. In particular, two events that occurred during the last period of the campaign drew our attention. These events had common large‐scale patterns and a similar mesoscale setting, characterised by southerly low‐level flow interacting with the Alpine orography, but the precipitation distribution was very different. During Intensive Observing Period IOP18 (31 October–1 November 2012), convective systems were responsible for intense rainfall mainly located over a flat area of the eastern Po Valley, well upstream of the orography. Conversely, during IOP19 (4/5 November 2012), heavy precipitation affected only the Alpine area. In addition to IOP18 and IOP19, the present study analyses other heavy‐precipitation episodes that display similar characteristics and which occurred over NEI during the autumn of recent years. A high‐resolution (2 km grid spacing) non‐hydrostatic NWP model and available observations are used for this purpose. The two different observed precipitation patterns are explained in terms of interaction between the impinging flow and the Alps. Depending on the thermodynamic profile, convection can be triggered when the impinging flow is forced to rise over a pre‐existing cold‐air layer at the base of the orography. In this situation a persistent blocked‐flow condition and upstream convergence are responsible for heavy rain localized over the plain. Conversely, if convection does not develop, flow‐over conditions are established and heavy rain affects the Alps. Numerical parameters proposed in the literature are used to support the analysis. Finally, the role of evaporative cooling beneath the convective systems is evaluated. It turns out that the stationarity of the systems upstream of the Alps is mainly attributable to persistent blocked‐flow conditions, while convective outflow slightly modifies the location of precipitation

On the relation between standard and μ\mu-symmetries for PDEs

We give a geometrical interpretation of the notion of $\mu$-prolongations of vector fields and of the related concept of $\mu$-symmetry for partial differential equations (extending to PDEs the notion of $\lambda$-symmetry for ODEs). We give in particular a result concerning the relationship between $\mu$-symmetries and standard exact symmetries. The notion is also extended to the case of conditional and partial symmetries, and we analyze the relation between local $\mu$-symmetries and nonlocal standard symmetries.Comment: 25 pages, no figures, latex. to be published in J. Phys.

Poincare' normal forms and simple compact Lie groups

We classify the possible behaviour of Poincar\'e-Dulac normal forms for dynamical systems in $R^n$ with nonvanishing linear part and which are equivariant under (the fundamental representation of) all the simple compact Lie algebras and thus the corresponding simple compact Lie groups. The ``renormalized forms'' (in the sense of previous work by the author) of these systems is also discussed; in this way we are able to simplify the classification and moreover to analyze systems with zero linear part. We also briefly discuss the convergence of the normalizing transformations.Comment: 17 pages; minor corrections in revised versio

Refugiados en Argentina. El rol de las organizaciones de derechos humanos de la comunidad peruana.

Desde 1985 hasta hoy, Argentina se ha convertido en uno de los países en el mundo que más estatutos de refugio ha otorgado. Pero a pesar de ello, el Estado argentino no cumple a menudo con sus obligaciones. En este artículo se describirán, través del análisis del trabajo de campo realizado en esas organizaciones, las acciones llevadas a cabo por las O.N.G. formadas en el seno de la comunidad peruana, las cuales asumieron el rol de protectoras de los derechos humanos de los solicitantes de refugio y refugiados que viven en Buenos Aires

Algunas consideraciones acerca de la experiencia en la investigación de poblaciones desplazadas en Buenos Aires (Argentina)

En Argentina, desde 1985 hasta el año 2006, han llegado nueve mil seiscientos ochenta y un (9.681) solicitantes de refugio y el Estado Nacional, a través de las instituciones competentes en la materia, les ha otorgado el estatuto de refugiado a dos mil quinientos ochenta y un (2.581) personas, acorde a lo prescripto por la Convención sobre el Estatuto de los Refugiados de 1951 (de aquí en adelante llamada “la Convención”)(C.E.Pa.Re., 20062). El estudio de esta población conlleva varias dificultades debido a la naturaleza intrínseca de la misma, sumado a otros factores que se analizarán en este artículo. El problema estudiado versa acerca de la relación entre los solicitantes de refugio y los refugiados con las instituciones (áreas del Estado, organismos internacionales y ONG nacionales e internacionales). El Estado argentino recién en el año 2006 aprobó la ley que regula la normativa general sobre refugio, luego de diez años de proyectos postergados en el Poder Legislativo. Desde 1961, año en que Argentina adoptó la normativa internacional, hasta 1985, el Gobierno argentino no había creado ninguna institución específica acorde a lo que estipula la Convención.Encuentro realizado junto con las V Jornadas de Sociología de la UNLP.Facultad de Humanidades y Ciencias de la Educació

¿Se puede estar excluido si no está incluido? : El caso de los Solicitantes de refugio en la Argentina

Los que eligen a la República Argentina como país de asilo ignoran que deben comenzar a transitar un largo camino hasta la obtener la condición de Refugiado, en el caso que se comprobara que su testimonio se atiene a lo establecido por la normativa vigente. El problema que se evidencia es que hasta alcanzar el Estatuto de Refugiada, porque cada un mes tiene que renovar su permiso de residencia para poder permanecer mientras su pedido está en consideración ante las autoridades competentes.Facultad de Humanidades y Ciencias de la Educació

On the notion of conditional symmetry of differential equations

Symmetry properties of PDE's are considered within a systematic and unifying scheme: particular attention is devoted to the notion of conditional symmetry, leading to the distinction and a precise characterization of the notions of ``true'' and ``weak'' conditional symmetry. Their relationship with exact and partial symmetries is also discussed. An extensive use of ``symmetry-adapted'' variables is made; several clarifying examples, including the case of Boussinesq equation, are also provided.Comment: 18 page

Weak Transversality and Partially Invariant Solutions

New exact solutions are obtained for several nonlinear physical equations, namely the Navier-Stokes and Euler systems, an isentropic compressible fluid system and a vector nonlinear Schroedinger equation. The solution methods make use of the symmetry group of the system in situations when the standard Lie method of symmetry reduction is not applicable.Comment: 23 pages, preprint CRM-284

Local and nonlocal solvable structures in ODEs reduction

Solvable structures, likewise solvable algebras of local symmetries, can be used to integrate scalar ODEs by quadratures. Solvable structures, however, are particularly suitable for the integration of ODEs with a lack of local symmetries. In fact, under regularity assumptions, any given ODE always admits solvable structures even though finding them in general could be a very difficult task. In practice a noteworthy simplification may come by computing solvable structures which are adapted to some admitted symmetry algebra. In this paper we consider solvable structures adapted to local and nonlocal symmetry algebras of any order (i.e., classical and higher). In particular we introduce the notion of nonlocal solvable structure