Abstract Based on an investigation already completed and a resurgence of migration policies and border control over the past four decades, this dossier exposes the emergence, action and contribution of organized civil society in the promotion and human rights protection of the human rights of migrants and refugees in the western border region of Mexico and the United States. In exposing the main intrinsic and extrinsic factors of the participation of different civil society organizations (CSO) on both sides of the border, it has been found that their emergence and humanitarian actions are mainly motivated by religious values and international solidarity and that regardless of being assistance-oriented or anti-establishment, they go through an institutionalization process that allows them to form networks and alliances and make a greater political impact. Revisiting the object of study, the “humanitarian reason” of the French sociologist-anthropologist Didier Fassin was taken into account. Thus, forms of "humanitarian government" could be observed from the bottom up. This is due to the fact that the CSO were formed from different social movements and/or due to the lack of attention from the State and local governments with respect to the migrants.

Resumen Partiendo de una investigación ya concluida y un recrudecimiento de políticas migratorias y control fronterizo durante las últimas cuatro décadas, este dossier expone la emergencia, la acción y la contribución de la sociedad civil organizada en la promoción y protección de los derechos humanos de migrantes y refugiados en la región fronteriza occidental de México y los Estados Unidos. Al exponer los principales factores que llevaron a una creciente participación de diferentes organizaciones de la sociedad civil (OSC) en ambos lados de la frontera, se ha encontrado que su surgimiento y acciones humanitarias son motivados principalmente por valores religiosos, humanitarios y de solidaridad internacional y que independientemente de ser asistencialistas o contestatarias recorren un proceso de institucionalización que les permita conformar redes y alianzas y realizar una mayor incidencia política. Volviendo al objeto de estudio de dicha investigación concluida, se tomó en cuenta la perspectiva de la “razón humanitaria” del sociólogo-antropólogo francés Didier Fassin. Así se pudieron observar formas de “gobierno humanitario” desde abajo hacia arriba. Esto se debe a que las OSC se formaron desde diferentes movimientos sociales y/o por la falta de atención del Estado y los gobiernos locales con respecto a los migrantes.

For linear time-invariant (LTI) state space systems it is well-known that its asymptotic stability can be related to solution properties of the Lyapunov matrix equation according to so-called inertia theorems. The question now arises how analogous results can be obtained for LTI descriptor systems (singular systems, differential-algebraic equations). The stability behaviour of a LTI descriptor system is characterized by the eigenvalues of the related matrix pencil. Additionally, by a quadratic Lyapunov function the stability problem can be discussed by solution properties of a generalized Lyapunov matrix equation including a singular coefficient matrix. To overcome this difficult problem of singularity, the Lyapunov matrix equation will be modified such that a regular Lyapunov matrix equation appears and asymptotic stability is preserved. This aim can be reached by shifting the system matrices in a well defined manner. For that the a priori knowledge of an upper bound of the eigenvalues is assumed. It will be discussed how to get such bound. The paper ends with an inertia theorem where the solution properties of a regular modified Lyapunov matrix equation are uniquely related to the asymptotic stability of the LTI descriptor system.

In recent years the analysis and synthesis of (mechanical) control systems in descriptor form has been established. This general description of dynamical systems is important for many applications in mechanics and mechatronics, in electrical and electronic engineering, and in chemical engineering as well. This contribution deals with linear mechanical descriptor systems and its control design with respect to a quadratic performance criterion. Here, the notion of properness plays an important role whether the standard Riccati approach can be applied as usual or not. Properness and non-properness distinguish between the cases if the descriptor system is exclusively governed by the control input or by its higher-order time-derivatives additionally. In the unusual case of non-proper systems a quite different problem of optimal control design has to be considered. Both cases will be solved completely.