Global shifts: U. S. immigration and the cultural impact of demographic change

At the turn of the millennium, we are witnessing intense new worldwide migration and refugee flows. There are now some 100 million transnational immigrants plus an estimated 30 million refugees displaced from their homelands. These flows are largely structured by the intensification of globalization--a process of economic, social, and cultural transformation rapidly accelerating in the last decade. Globalization has increased immigration in a variety of ways. First, transnational capital flows (roughly a trillion dollars cross national boundaries every day) tend to stimulate migration because where capital flows, immigrants tend to follow. Second, the new information and communication technologies that are at the heart of globalization tend to stimulate migration because they encourage new standards of consumption and life-style choices. Would-be immigrants imagine better opportunities elsewhere and mobilize to achieve them. Third, the affordability of mass transportation--last year approximately 1.5 billion airline tickets were sold--has put the migration option within the reach of millions who heretofore could not consider it. Fourth, globalization has stimulated new migration because it has produced uneven results--big winners and losers.Demography ; Economic conditions ; Emigration and immigration

Multichannel receivers from ofdm and tdma in mobile communications

This paper addresses the use of multichannel receivers for blind equalization in TDMA under frequency selective channels and OFDM systems in frequency flat fading channels. A new criteria is proposed for blind equalization of finite length mobile channels.Peer ReviewedPostprint (published version

Diversity techniques for blind channel equalization in mobile communications

A blind algorithm for channel distortion compensation is presented which can be employed in spatial or temporal diversity receivers. The proposed technique can be used in frequency selective and frequency flat fading mobile channels, using burst transmission schemes in the first case and OFDM modulation in the second one. The algorithm is base on a deterministic criteria and is suited for estimation when short sets of data are available.Peer ReviewedPostprint (published version

Transform modulations for mobile communications

A new modulation scheme called transform modulations is proposed which improves the system performance in frequency-flat fading mobile channels. They ameliorate the effect of the fadings over the transmitted signal by spreading the information in time, using a linear transform operator. The design of this scheme is discussed and its advantages are shown by means of simulations. The relationship of this scheme with OFDM modulation is also analyzed.Peer ReviewedPostprint (published version

Sobre unos afloramientos de rocas verdes de sierra de Gádor (Cordilleras Béticas)

Se estudian tres pequeños afloramientos de rocas verdes existentes en la parte occidental de sierra de Gádor (provincia de Almería).Se han identificado los siguientes minerales: oligoclasa, clorita, pistacita, actinolita, sericita, cuarzo, calcita y óxidos de hierro.Estas determinaciones se han hecho con el microscopio de polarización y, debido al pequeño tamaño de algunos cristales, nos hemos visto obligados a realizar diagramas de difracción por rayos X para completar el conocimiento de los minerales

Redundancy in block coded modulations for channel equalization based on spatial and temporal diversity

Linear block codes in the complex field can be applied in spatial and/or temporal diversity receivers in order to develop high performance schemes for (almost-) blind equalization in mobile communications. The proposed technique uses the structure of the encoded transmitted information (with redundancy) to achieve equalization schemes based on a deterministic criterion. Simulations show that the proposed technique is more efficient than other schemes that follow similar equalizer structures. The result is an algorithm that provides the design of channel equalizers in low EbNo scenarios.Peer ReviewedPostprint (published version

Blind equalization based on spatial and temporal diversity in block coded modulations

Linear block codes can be applied in spatial and/or temporal diversity receivers in order to develop high performance schemes for blind equalization in mobile communications. The proposed technique uses the structure of the encoded transmitted information (with redundancy) to achieve equalization schemes based on a deterministic criterion. Simulations show that the proposed technique is more efficient than other schemes that follow similar equalizer structures. The result is an algorithm that provides the design of blind channel equalizers in low EbNo scenarios.Peer ReviewedPostprint (published version