Moving embedded lattice solitons

It was recently proved that isolated unstable "embedded lattice solitons" (ELS) may exist in discrete systems. The discovery of these ELS gives rise to relevant questions such as the following: are there continuous families of ELS?, can ELS be stable?, is it possible for ELS to move along the lattice?, how do ELS interact?. The present work addresses these questions by showing that a novel differential-difference equation (a discrete version of a complex mKdV equation) has a two-parameter continuous family of exact ELS. The numerical tests reveal that these solitons are stable and robust enough to withstand collisions. The model may apply to the description of a Bose-Einstein condensate with dipole-dipole interactions between the atoms, trapped in a deep optical-lattice potential.Comment: 13 pages, 11 figure

The nature of GRB-selected submillimeter galaxies: hot and young

We present detailed fits of the spectral energy distributions (SEDs) of four submillimeter (submm) galaxies selected by the presence of a gamma-ray burst (GRB) event (GRBs 980703, 000210, 000418 and 010222). These faint ~3 mJy submm emitters at redshift ~1 are characterized by an unusual combination of long- and short-wavelength properties, namely enhanced submm and/or radio emission combined with optical faintness and blue colors. We exclude an active galactic nucleus as the source of long-wavelength emission. From the SED fits we conclude that the four galaxies are young (ages <2 Gyr), highly starforming (star formation rates ~150 MSun/yr), low-mass (stellar masses ~10^10 MSun) and dusty (dust masses ~3x10^8 MSun). Their high dust temperatures (Td>45 K) indicate that GRB host galaxies are hotter, younger, and less massive counterparts to submm-selected galaxies detected so far. Future facilities like Herschel, JCMT/SCUBA-2 and ALMA will test this hypothesis enabling measurement of dust temperatures of fainter GRB-selected galaxies.Comment: 9 pages, 2 figures, submitted to ApJ, for SED templates, see http://archive.dark-cosmology.dk

Technology and teaching in higher education: A simulation applied to the integration of concepts taught in postgraduate courses

Introducción: El objetivo de este trabajo fue implementar tecnologías de la información y la comunicación (TIC) a nivel de posgrado. En este caso particular se usó USINA, un simulador para la toma de decisiones diseñado por el Centro de Innovaciones en Tecnología y Pedagogía (CITEP), de la Universidad de Buenos Aires. Ésta permite trabajar con narraciones, estudio de casos y utilizar el “error” como método pedagógico. Métodos: 1) Diseñar una secuencia de pantallas para ser montadas en USINA utilizándola como herramienta de integración de conceptos en dos cursos de posgrado: Downstream Processing de proteínas (DSP) y Aplicaciones, Síntesis y Análisis de Péptidos Sintéticos (ASAP). 2) Aplicar una encuesta anónima para evaluar la eficiencia de USINA. 3) Realizar una clase presencial para intercambiar opiniones sobre la experiencia. Resultados y Discusión: En ambos cursos (DSP y ASAP) la experiencia resultó exitosa. El alumnado consideró que el uso de USINA permitió el andamiaje de conocimientos y la integración de conceptos al situarlo en el rol de experto. El uso de las TIC en los niveles educativos superiores sigue siendo una asignatura pendiente. A través de la experiencia aquí analizada, se abre la posibilidad de llevar esta herramienta a cursos de pregrado y con mayor número de estudiantesIntroduction: The aim of this work was to implement information and communication technologies (ICTs) at postgraduate level. In this particular case, USINA, a decision-making simulator designed by the Center for Innovation in Technology and Education (CITEP), of the University of Buenos Aires, was used. It allows working with stories, case studies and uses the "error" as a teaching method. Methods: 1) Design a sequence of screens to be mounted in the USINA platform to use it as a tool for the integration of concepts in two postgraduate courses: Protein Downstream Processing (DSP) and Applications, Synthesis and Analysis of Synthetic Peptides (ASAP). 2) Apply anonymous quiz to evaluate the efficiency of USINA. 3) Perform a class attendance to exchange opinions on the experience. Results: During both courses (DSP and ASAP) the experience was very successful. The students felt that the use of USINA enhanced learning and helped integrating concepts by situating them in the role of experts. Discussion: The use of ICTs in higher levels of education remains a pending issue. Through the experience here analyzed the possibility to bring this tool to undergraduate courses and more students is opene

Atorvastatin and sildenafil decrease vascular TGF-β levels and MMP-2 activity and ameliorate arterial remodeling in a model of renovascular hypertension

AbstractImbalanced matrix metalloproteinase (MMP)-2 activity and transforming growth factor expression (TGF-β) are involved in vascular remodeling of hypertension. Atorvastatin and sildenafil exert antioxidant and pleiotropic effects that may result in cardiovascular protection. We hypothesized that atorvastatin and sildenafil alone or in association exert antiproliferative effects by down-regulating MMP-2 and TGF-β, thus reducing the vascular hypertrophy induced by two kidney, one clip (2K1C) hypertension.Sham and 2K1C rats were treated with oral atorvastatin 50mg/kg, sildenafil 45mg/kg, or both, daily for 8 weeks. Blood pressure was monitored weekly. Morphologic changes in the aortas were studied. TGF-β levels were determined by immunofluorescence. MMP-2 activity and expression were determined by in situ zymography, gel zymography, Western blotting, and immunofluorescence. The effects of both drugs on proliferative responses of aortic smooth muscle cells to PDGF and on on MMP-2 activity in vitro were determined. Atorvastatin, sildenafil, or both drugs exerted antiproliferative effects in vitro. All treatments attenuated 2K1C-induced hypertension and prevented the increases in the aortic cross-sectional area and media/lumen ratio in 2K1C rats. Aortas from 2K1C rats showed higher collagen deposition, TGF-β levels and MMP-2 activity and expression when compared with Sham-operated animals. Treatment with atorvastatin and/or sildenafil was associated with attenuation of 2K1C hypertension-induced increases in these pro-fibrotic factors. However, these drugs had no in vitro effects on hr-MMP-2 activity.Atorvastatin and sildenafil was associated with decreased vascular TGF-β levels and MMP-2 activity in renovascular hypertensive rats, thus ameliorating the vascular remodeling. These novel pleiotropic effects of both drugs may translate into protective effects in patients

The very red afterglow of GRB 000418 - further evidence for dust extinction in a GRB host galaxy

We report near-infrared and optical follow-up observations of the afterglow of the Gamma-Ray Burst 000418 starting 2.5 days after the occurrence of the burst and extending over nearly seven weeks. GRB 000418 represents the second case for which the afterglow was initially identified by observations in the near-infrared. During the first 10 days its R-band afterglow was well characterized by a single power-law decay with a slope of 0.86. However, at later times the temporal evolution of the afterglow flattens with respect to a simple power-law decay. Attributing this to an underlying host galaxy we find its magnitude to be R=23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K=4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long) bursts are associated with events in star-forming regions.Comment: Accepted for publication in The Astrophysical Journal. 12 pages; citations & references updated; minor textual change

The politics of fission: an analysis of Faction Breakaways among Italian Parties (1946&#8211;2011)

This article investigates intra-party politics and explores the determinants of factional breakaways, going beyond the unitary actor assumption. It presents a game-theoretic model that focuses on intra-party competition and bargaining dynamics to analyse the interplay between party leaders and minority factions. It tests several hypotheses based on the formal model using a new dataset that contains information about the strength and policy positions of factions inside Italian parties, from 1946 to 2011, measured through quantitative content analysis of motions presented during party congresses. The results show that office, policy and electoral motives influence factions' decisions to break away. Other elements - such as intra-party democracy, the electoral system and party system competitiveness - also affect leaders' attitudes toward compromising and alter the likelihood of a split

Binge flying: Behavioural addiction and climate change

Recent popular press suggests that ‘binge flying’ constitutes a new site of behavioural addiction. We theoretically appraise and empirically support this proposition through interviews with consumers in Norway and the United Kingdom conducted in 2009. Consistent findings from across two national contexts evidence a growing negative discourse towards frequent short-haul tourist air travel and illustrate strategies of guilt suppression and denial used to span a cognitive dissonance between the short-term personal benefits of tourism and the air travel’s associated long-term consequences for climate change. Tensions between tourism consumption and changing social norms towards acceptable flying practice exemplify how this social group is beginning to (re)frame what constitutes ‘excessive’ holiday flying, despite concomitantly continuing their own frequent air travels

Intra-party politics in 140 characters

Scholars have emphasized the need to deepen investigation of intraparty politics. Recent studies look at social media as a source of information on the ideological preferences of politicians and political actors. In this regard, the present article tests whether social media messages published by politicians are a suitable source of data. It applies quantitative text analysis to the public statements released by politicians on social media in order to measure intraparty heterogeneity and assess its effects. Three different applications to the Italian case are discussed. Indeed, the content of messages posted online is informative on the ideological preferences of politicians and proved to be useful to understand intraparty dynamics. Intraparty divergences measured through social media analysis explain: (a) a politician\u2019s choice to endorse one or another party leader, (b) a politician\u2019s likelihood to switch off from his or her parliamentary party group; and (c) a politician\u2019s probability to be appointed as a minister

Changing politics, changing language : The effect of institutional and communicative changes on political language measured through content analysis of Italian intra-party debates

This paper examines the changes in political language that occurred after 1989 in Italy and focuses on textual documents drafted by intra-party subgroups between 1946 and 2010 that were related to the internal debates of Italian political parties. These documents, which are addressed to party members and activists rather than the wider public, have been analyzed through quantitative text analysis of word frequencies. The results confirm that a few relevant changes occurred that involve the lexicon, tone, and content of messages. However, concepts such as left and right are still relevant, and we observed neither a strong decline in the use of ideological terms nor a wider usage of populist words. Despite the growing personalization of politics, the main political leaders are not frequently mentioned, with two exceptions: Prodi and Berlusconi. Overall, there is a distance between intra-party politics and the logic of entertainment