The role of interfaces in CoFe/IrMn exchange biased systems

A trilayer system consisting of an IrMn layer exchanged coupled to two CoFe layers of equal thickness has been studied. A single stage reversal was observed over a wide range of temperatures. Two bilayers with the same thicknesses of the pinning layer but different ferromagnetic thicknesses were also studied. By comparing the magnetic properties of these three stacks the effect of the interfacial area on the exchange field and the coercivity has been determined. We find that the interfacial area has a very minor effect on the exchange field H-ex and the blocking temperature (T-B) but causes a doubling of the coercivity (H-c). This indicates that H-c is dominated by the interface whereas the exchange bias is controlled by volumetric effects

Identifying genetic determinants of T cell-dependent autoimmunity using forward genetics

Rheumatoid arthritis (RA) affects 0.5-1% of the population and is an important health and socioeconomic problem. RA has a high degree of heritability. Thus, extensive efforts have been made to better understand the genetic variability contributing to disease susceptibility. However, dissecting the genetic component of RA in humans has been difficult due to heterogeneity in the human population, multiple testing issues, and lack of accessibility to relevant tissues for proof-of-concept studies. Genetic studies in mouse model systems circumvent these problems, enhancing the possibility to identify disease regulating genetic variants. Here, we use a forward genetics approach in mice to identify and characterize genetic determinants of RA and related autoimmune diseases. First, we have mapped quantitative trait loci (QTL) regulating experimental arthritis using linkage analysis, and then isolated these QTL in congenic strains for in depth functional characterization. Using this approach, we make several important observations. In the first study, we find that promoter polymorphisms regulating expression of the vitamin D receptor affect T cell activation and T cell-driven collagen-induced arthritis. These findings are particularly interesting considering the long-standing association between serum vitamin D and several autoimmune diseases. In the second study, we discover a spontaneous insertion of a long terminal repeat which leads to a deficiency in the SH3GL1 gene (Endophilin A2), protecting mice in several arthritis models. We are first to identify the immunomodulatory properties of SH3GL1, which may prove to be a valuable therapeutic target. In the third study, we identify a polymorphic estrogen receptor binding site that regulates susceptibility to experimental arthritis and other autoimmune models by interfering with estrogen regulation of the T cell marker CD2. These results suggest an important role for CD2 and estrogen in shaping the sexually dimorphic immune response. Collectively, our findings make a significant contribution towards the understanding of RA genetics while demonstrating the value of animal models

La deposición de Fotino de Sirmio

[email protected] artículo estudia la condena y deposición del obispo Fotino de Sirmio en los años 346 y 347 d.C. Las fuentes principales son Código Teodosiano, Epifanio de Salamina (Panarion Haereticon), Nestorio de Constantinopla (Sermo XII), Hilario de Poitiers (Fragrnenta Historica), Atanasio de Alejandría (Apologia confra arianos e Historia arianorum ad monachos), Sozomeno (Historia Ecciesiastica), Libanio de Antioquía (Oratio XVIII) y Sócrates (Historia Ecclesiastica).Ibis article deals with Bishop Photin of Sirmiums sentence and deposition in years 346 and 347 AD. The main sources are Theodosian Code, Epiphanius of Salamis (Panarion Haereticon), Nestorius of Constantinople (Sermo XII), Hilary of Poitiers (Fragmenta Historica), Athanasius of Alexandria (Apologia contra arianos and Historia arianorum ad monachos), Sozomen (Historia Ecciesiastica), Libanius of Antioch (Oratio XVIII) and Socrates (Historia Ecclesiastica)

La agonía del Imperio Romano de Occidente

[email protected] presente artículo afronta algunos problemas relativos a la historia romana de los años 472-476 d.C. Las fuentes principales son: Juan de Antioquía, Procopio de Cesarea y Malco.This article deals with some problems concerning roman history in years 472 – 476 A.D. The main sources are John of Antioch, Priscus, Procopius of Caesarea and Malchus

La controversia historiográfica en torno al fin de la Edad Antigua

[email protected] las doctrinas que aluden al término de la Edad Antigua pueden efectuarse tres grupos. El primero se halla constituido por aquéllas que lo relacionan con las luchas de cristianos contra paganos. Forman el segundo las hipótesis que lo unen a las trayectorias de ambos sectores del Imperio Romano en los siglos IV, V y VI d.C. El tercero abarca las ideas que lo vinculan a la génesis del Islam y sus consecuencias

Cryptanalysis of a new chaotic cryptosystem based on ergodicity

This paper analyzes the security of a recent cryptosystem based on the ergodicity property of chaotic maps. It is shown how to obtain the secret key using a chosen-ciphertext attack. Some other design weaknesses are also shown.Comment: 10 pages, 5 figure