Tuning magnetic chirality by dipolar interactions

Chiral magnetism has gained enormous interest in recent years because of the anticipated wealth of applications in nanoelectronics. The demonstrated stabilization of chiral magnetic domain walls and skyrmions has been attributed to the actively investigated Dzyaloshinskii-Moriya interaction. Recently, however, predictions were made that suggest dipolar interactions can also stabilize chiral domain walls and skyrmions, but direct experimental evidence has been lacking. Here we show that dipolar interactions can indeed stabilize chiral domain walls by directly imaging the magnetic domain walls using scanning electron microscopy with polarization analysis. We further show that the competition between the Dzyaloshinskii-Moriya and dipolar interactions can reverse the domain-wall chirality. Finally, we suggest that this competition can be tailored by a Ruderman-Kittel-Kasuya-Yosida interaction. Our work therefore reveals that dipolar interactions play a key role in the stabilization of chiral spin textures. This insight will open up new routes towards balancing interactions for the stabilization of chiral magnetism

Asymmetric magnetic bubble expansion under in-plane field in Pt/Co/Pt: effect of interface engineering

We analyse the impact of growth conditions on asymmetric magnetic bubble expansion under in-plane field in ultrathin Pt / Co / Pt films. Specifically, using sputter deposition we vary the Ar pressure during the growth of the top Pt layer. This induces a large change in the interfacial structure as evidenced by a factor three change in the effective perpendicular magnetic anisotropy. Strikingly, a discrepancy between the current theory for domain-wall propagation based on a simple domain-wall energy density and our experimental results is found. This calls for further theoretical development of domain-wall creep under in-plane fields and varying structural asymmetry.Comment: 16 pages, 3 figure

Microwave and RF Applications for Micro-resonator based Frequency Combs

Photonic integrated circuits that exploit nonlinear optics in order to generate and process signals all-optically have achieved performance far superior to that possible electronically - particularly with respect to speed. We review the recent achievements based in new CMOS-compatible platforms that are better suited than SOI for nonlinear optics, focusing on radio frequency (RF) and microwave based applications that exploit micro-resonator based frequency combs. We highlight their potential as well as the challenges to achieving practical solutions for many key applications. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement. We review recent work on a photonic RF Hilbert transformer for broadband microwave in-phase and quadrature-phase generation based on an integrated frequency optical comb. The comb is generated using a nonlinear microring resonator based on a CMOS compatible, high-index contrast, doped-silica glass platform. The high quality and large frequency spacing of the comb enables filters with up to 20 taps, allowing us to demonstrate a quadrature filter with more than a 5-octave (3 dB) bandwidth and an almost uniform phase response.Comment: 10 pages, 6 figures, 68 references. arXiv admin note: substantial text overlap with arXiv:1512.0174

Estudios postcoloniales : ensayos fundamentales

278 p. : il. ; 22 cm.Libro ElectrónicoEste libro presenta una amplia panorámica de los estudios postcoloniales, un campo heterogéneo de prácticas teóricas que se ha ido constituyendo en el mundo académico anglosajón a partir de la mitad de la década de 1980. Se ofrecen aquí traducidos al castellano dos de los textos fundamentales que pueden situarse en el origen de los estudios postcoloniales —el de Gayatri Spivak, «Los Estudios de la Subalternidad. Deconstruyendo la historiografía » (1984), y el de Chandra Talpade Mohanty, «Bajo los ojos de Occidente» (1985). Las intervenciones de Ella Shohat y Stuart Hall documentan la discusión que se desarrolló, con particular intensidad a lo largo de la primera mitad de la década de 1990, sobre el «significado de lo “post” en el término postcolonial». Los artículos de Dipesh Chakrabarty, Achille Mbembe, Robert Young, Nirmal Puwar, Sandro Mezzadra y Federico Rahola dan cuenta, por último, de la evolución del debate en los últimos años a partir de distintas perspectivas teóricas y posiciones «geográficas».índice INTRODUCCIÓN. Sandro Mezzadra 15 1. Estudios de la Subalternidad. Deconstruyendo la Historiografía. Gayatri Chakravorty Spivak 33 2. Bajo los ojos de Occidente. Saber académico y discursos coloniales. Chandra Talpade Mohanty 69 3. Notas sobre lo «postcolonial» Ella Shohat 103 4. ¿Cuándo fue lo postcolonial? Pensar al límite. Stuart Hall 121 5. La historia subalterna como pensamiento político. Dipesh Chakrabarty 145 6. Al borde del mundo. Fronteras, territorialidad y soberanía en África. Achille Mbembe 167 7. Nuevo recorrido por (las) Mitologías Blancas. Robert J. C. Young 197 8. Poses y construcciones melodramáticas. Nirmal Puwar 237 9. La condición postcolonial. Unas notas sobre la cualidad del tiempo histórico en el presente global. Sandro Mezzadra y Federico Rahola 26

El activismo religioso conservador en Latinoamérica

Pertenece a la colección Religión, Género y Sexualidad / dirigida por Juan M. Vaggione ; v.3El libro reúne un conjunto de análisis que ponen en evidencia la heterogeneidad y la complejidad de las estrategias de influencia de la religión como uno de los principales sostenes de sistemas heteronormativos en nuestras sociedades contemporáneas. Tanto al nivel de los actores como de los discursos, las formas en que las religiones influencian las discusiones sobre políticas de sexualidad han adoptado diversas modalidades de actuación adaptándose a los momentos políticos. Así, los artículos que integran la compilación se dirigen a complejizar el rol de lo religioso en la política sexual contemporánea incluyendo en esta problematización distintos ejes de análisis y marcos teóricos. Haciendo foco en diferentes países de América Latina, con sus escenarios y problemas, los artículos abordan las variadas dimensiones del activismo religioso conservador en nuestra región

Elites rioplatenses del siglo XIX : Biografías, representaciones, disidencias y fracasos

Rioplatenses elites of the 19th century : Biographies, representations, dissidences and failuresPublishedDesde la independencia hispanoamericana, los políticos continentales llevaron una vida intensa, afanosa y, en ocasiones contradictoria, en sus luchas por el poder. En diferentes circunstancias, actuaron como militares, periodistas, diplomáticos, abogados, profesores o escritores. Sus vidas simbolizan la antigua confrontación entre liberalismo y conservadurismo; centralismo y federalismo, cuyo destino dejó una impronta en el balance de poder regional. Este libro tiene como objetivo general introducirse a ese mundo de los políticos hispanoamericanos, y los problemas de la historia política continental del primer siglo de vida independiente, en particular en la región del Río de la Plata

The National Security Education Program and Its Service Requirement: An Exploratory Study of What Areas of Government and for What Duration National Security Education Program Recipients Have Worked

The National Security Education Program, established under the National Security Education Act of 1991, has had a post-funding service requirement in the Federal Government for undergraduate scholarship and graduate fellowship recipients since its inception. The service requirement, along with the concern that the National Security Education Program was and remains funded by the United States Department of Defense, was very controversial in the early years of the program and remains a concern for some faculty and scholarly organizations to this day. Questions arise about whether the National Security Education Program is successfully achieving government objectives of employing National Security Education Program Alumni in critical areas of federal service and how long National Security Education Program Alumni are working in such positions. The research question of this study is: In what areas of government and for what duration (retention) National Security Education Program Alumni worked? This research project surveyed National Security Education Program Alumni from the first ten years of the program as a means to answer the research question. The project was a quantitative endeavor and the results demonstrate that the National Security Education Program is successful in meeting the goals, both past and present, set forth in the legislation for the scholarship and fellowship initiatives of the program

Pathological evaluation to the effect of some probiotics on the health and immune status of Nile Tilapia (Oreochromis niloticus)

SUMMARY T he safety and efficiency of Bacillus subtilis and/or Lactobacillus acidophilus, as potential probiotics, were evaluated histopathologically and immnunologically besides after challenge infection through an experiment using 960 Nile tilapia (Oreochromis niloticus) reared in aquaria. The experimented fish divided into 4 equal groups. Groups 1-3 fed daily on a basal diet supplemented with probiotics, the 4 th group served as a control and fed on basal diet only. All fish fed at a rate of 5% of the body weight for 1 and 2 months. The feed conversion and specific growth rates showed no significant change after one month of application but a significant to non-significant increase were remarkable after 2 months of treatment. The survival rate was significantly increased in the fish given B. subtilis and L. acidophilus for one and two months after application. The histopathological studies revealed minimal pathological alterations, in the examined organs of Nile tilapia from different supplemented groups, but an obvious activation in the hematopoietic tissues and melanomacrophage centers were recognized. The serum bactericidal activity and the mortality after the challenge infections were varied with the type of probiotic bacteria used, type of pathogen tested and period of application but as a general observation, it was high in the group that given a mixture of B. subtilis and L. acidophilus and groups treated for 2 months. Based on the following observations where, the tested bacteria proved to have a potential probiotic effect, enhancing the immunity and health status of the experimental fish. Such probiotics promoted the resistance against the bacterial infections. No remarkable pathological alterations were recognized in groups treated with single or mixed probiotic candidate. It could be concluded that, one month application was sufficient and a mixture of the two probiotics was superior. However, full commercial cost benefit analysis is recommended

Pathological and clinicopathological studies on reperfusion of ischemic intestine

SUMMARY The present work was carried on dogs as experimental model to assess the histological and clinicopathological changes that associated with ischemiareperfusion injury of intestine. Serum biochemical changes with correlation to histopathological alterations as a result of induction of ischemia-reperfusion were clarified. A total 15 healthy male mongrel dogs of weighing 9 to 12 kg and ageing one to five years old were allocated into 3 groups according to the pathway of induction of intestinal ischemia. Blood samples were taken from dogs before and after induction of ischemia-reperfusion injury for determination serum biochemical and blood coagulation changes. A significant hypercoagulability in all groups at the end of ischemic and reperfusion times were recorded. Serum biochemical changes associated with IRI in intestine revealed a significant increase in (ALT, AST, ALP, LDH and AMYL), enzymes activities with ischemic and reperfusion times, when compared with their activity at zero-time. Blood urea, creatinine and glucose determination showed significant increase in their concentration during ischemia and reperfusion times. Also C-reactive protein revealed a significant increase in their titer with all groups at the end of ischemic time and with reperfusion time. Ischemia/ reperfusion lesions of intestinal region revealed congestion, hemorrhages and cyanosis associated with damage of intestinal epithelium and serosal layer with different grades. The histological findings demonstrated severe destruction of intestinal segment after reperfusion in comparison with ischemia. On the other hand, ischemia/ reperfusion were reflected on hepatic and renal parenchyma with different grades according to ischemic pathway