Floquet oscillations in periodically driven Dirac systems

Electrons in a lattice exhibit time-periodic motion, known as Bloch oscillation, when subject to an additional static electric field. Here, we show that a corresponding dynamics can occur upon replacing the spatially periodic potential by a time-periodic driving: Floquet oscillations of charge carriers in a spatially homogeneous system. The time lattice of the driving gives rise to Floquet bands that take on the role of the usual Bloch bands. For two different drivings (harmonic driving and periodic kicking through pulses) of systems with linear dispersion we demonstrate the existence of such oscillations, both by directly propagating wave packets and based on a complementary Floquet analysis. The Floquet oscillations feature richer oscillation patterns than their Bloch counterpart and enable the imaging of Floquet bands. Moreover, their period can be directly tuned through the driving frequency. Such oscillations should be experimentally observable in effective Dirac systems, such as graphene, when illuminated with circularly polarized light

IMAGENS DE ANÚNCIOS PUBLICITÁRIOS E CONSUMO: CONTRIBUIÇÕES PEDAGÓGICAS E AMBIENTAIS

http://dx.doi.org/10.5902/2236117010739This paper discusses the relationship between advertisements images, consumer culture and educational environment. We start from an experience with teachers from public schools, where are discussed the relationship between publicity images and product consumption, and reflected the importance of addressing this issue in the educational context, with a focus on environmental issues. In this sense, the images served as advertising tools to reflect the pedagogical practice of teachers located in São Gabriel - RS. The empirical data of this study were produced through part of a workshop held with 23 teachers in October 2012.http://dx.doi.org/10.5902/2236117010739O presente texto pretende discutir a estreita relação existente entre imagens de anúncios publicitários, a cultura consumista e o espaço educativo. Partimos de uma experiência com docentes da rede pública, onde se discutiu a relação entre imagens publicitárias e o consumo de produtos, e se refletiu sobre a importância de se abordar esta temática no contexto educativo, com foco na questão ambiental. Nesse sentido, as imagens publicitárias serviram de subsídios para pensar a prática pedagógica de docentes da rede pública de São Gabriel - RS. Os dados empíricos desse estudo foram produzidos através de parte de uma oficina realizada com 23 professores no mês de outubro de 2012

IMAGENS DE ANÚNCIOS PUBLICITÁRIOS E CONSUMO: CONTRIBUIÇÕES PEDAGÓGICAS E AMBIENTAIS

http://dx.doi.org/10.5902/2236117010739This paper discusses the relationship between advertisements images, consumer culture and educational environment. We start from an experience with teachers from public schools, where are discussed the relationship between publicity images and product consumption, and reflected the importance of addressing this issue in the educational context, with a focus on environmental issues. In this sense, the images served as advertising tools to reflect the pedagogical practice of teachers located in São Gabriel - RS. The empirical data of this study were produced through part of a workshop held with 23 teachers in October 2012.http://dx.doi.org/10.5902/2236117010739O presente texto pretende discutir a estreita relação existente entre imagens de anúncios publicitários, a cultura consumista e o espaço educativo. Partimos de uma experiência com docentes da rede pública, onde se discutiu a relação entre imagens publicitárias e o consumo de produtos, e se refletiu sobre a importância de se abordar esta temática no contexto educativo, com foco na questão ambiental. Nesse sentido, as imagens publicitárias serviram de subsídios para pensar a prática pedagógica de docentes da rede pública de São Gabriel - RS. Os dados empíricos desse estudo foram produzidos através de parte de uma oficina realizada com 23 professores no mês de outubro de 2012

The Unexpected Effects of Beneficial and Adverse Social Experiences during Adolescence on Anxiety and Aggression and Their Modulation by Genotype

Anxiety and aggression are part of the behavioral repertoire of humans and animals. However, in their exaggerated form both can become maladaptive and result in psychiatric disorders. On the one hand, genetic predisposition has been shown to play a crucial modulatory role in anxiety and aggression. On the other hand, social experiences have been implicated in the modulation of these traits. However, so far, mainly experiences in early life phases have been considered crucial for shaping anxiety-like and aggressive behavior, while the phase of adolescence has largely been neglected. Therefore, the aim of the present study was to elucidate how levels of anxiety-like and aggressive behavior are shaped by social experiences during adolescence and serotonin transporter (5-HTT) genotype. For this purpose, male mice of a 5-HTT knockout mouse model including all three genotypes (wildtype, heterozygous and homozygous 5-HTT knockout mice) were either exposed to an adverse social situation or a beneficial social environment during adolescence. This was accomplished in a custom-made cage system where mice experiencing the adverse environment were repeatedly introduced to the territory of a dominant opponent but had the possibility to escape to a refuge cage. Mice encountering beneficial social conditions had free access to a female mating partner. Afterwards, anxiety-like and aggressive behavior was assessed in a battery of tests. Surprisingly, unfavorable conditions during adolescence led to a decrease in anxiety-like behavior and an increase in exploratory locomotion. Additionally, aggressive behavior was augmented in animals that experienced social adversity. Concerning genotype, homozygous 5-HTT knockout mice were more anxious and less aggressive than heterozygous 5-HTT knockout and wildtype mice. In summary, adolescence is clearly an important phase in which anxiety-like and aggressive behavior can be shaped. Furthermore, it seems that having to cope with challenge during adolescence instead of experiencing throughout beneficial social conditions leads to reduced levels of anxiety-like behavior

Formaldehyde evolution in US wildfire plumes during the Fire Influence on Regional to Global Environments and Air Quality experiment (FIREX-AQ)

Formaldehyde (HCHO) is one of the most abundant non-methane volatile organic compounds (VOCs) emitted by fires. HCHO also undergoes chemical production and loss as a fire plume ages, and it can be an important oxidant precursor. In this study, we disentangle the processes controlling HCHO by examining its evolution in wildfire plumes sampled by the NASA DC-8 during the Fire Influence on Regional to Global Environments and Air Quality experiment (FIREX-AQ) field campaign. In 9 of the 12 analyzed plumes, dilution-normalized HCHO increases with physical age (range 1&ndash;6&thinsp;h). The balance of HCHO loss (mainly via photolysis) and production (via OH-initiated VOC oxidation) seems to control the sign and magnitude of this trend. Plume-average OH concentrations, calculated from VOC decays, range from &minus;0.5 (&plusmn;&thinsp;0.5)&thinsp;&times;&thinsp;106 to 5.3 (&plusmn;&thinsp;0.7)&thinsp;&times;&thinsp;106&thinsp;cm&minus;3. The production and loss rates of dilution-normalized HCHO seem to decrease with plume age. Plume-to-plume variability in dilution-normalized secondary HCHO production correlates with OH abundance rather than normalized OH reactivity, suggesting that OH is the main driver of fire-to-fire variability in HCHO secondary production. Analysis suggests an effective HCHO yield of 0.33 (&plusmn;&thinsp;0.05) per VOC molecule oxidized for the 12 wildfire plumes. This finding can help connect space-based HCHO observations to the oxidizing capacity of the atmosphere and to VOC emissions. &nbsp; Full List of Authors Jin Liao1,2, Glenn M. Wolfe1, Reem A. Hannun1,3, Jason M. St. Clair1,3, Thomas F. Hanisco1, Jessica B. Gilman4, Aaron Lamplugh4,5, Vanessa Selimovic6, Glenn S. Diskin7, John B. Nowak7, Hannah S. Halliday8, Joshua P. DiGangi7, Samuel R. Hall9, Kirk Ullmann9, Christopher D. Holmes10, Charles H. Fite10, Anxhelo Agastra10, Thomas B. Ryerson4,a, Jeff Peischl4,5, Ilann Bourgeois4,5, Carsten Warneke4, Matthew M. Coggon4,5, Georgios I. Gkatzelis4,5,b, Kanako Sekimoto11, Alan Fried12, Dirk Richter12, Petter Weibring12, Eric C. Apel9, Rebecca S. Hornbrook9, Steven S. Brown4, Caroline C. Womack4,5, Michael A. Robinson4,5, Rebecca A. Washenfelder4, Patrick R. Veres4, and J. Andrew Neuman4,5 1Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA 2Goddard Earth Science Technology and Research (GESTAR) II, University of Maryland Baltimore County, Baltimore, MD, USA 3Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD, USA 4NOAA Chemical Science Laboratory (CSL), Boulder, CO, USA 5Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder, CO, USA 6Department of Chemistry, University of Montana, Missoula, MT, USA 7NASA Langley Research Center, Hampton, VA, USA 8Environmental Protection Agency, Durham, NC, USA 9Atmospheric Chemistry Observations &amp; Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA 10Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, USA 11Yokohama City University, Yokohama, Japan 12Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, CO, USA anow at: Scientific Aviation, Boulder, CO, USA bnow at: Forschungszentrum J&uuml;lich GmbH, J&uuml;lich, Nordrhein-Westfalen, Germany </ul

Primary fibroblast co-culture stimulates growth and metabolism in Sdhb-impaired mouse pheochromocytoma MTT cells

Pheochromocytomas and paragangliomas (PGLs) due to mutations of succinate dehydrogenase (SDH) B, a subunit of the SDH complex with a role in the Krebs cycle and the respiratory chain, tend to be larger at diagnosis and more prone to metastatic disease than other tumors. This presentation contrasts with the behavior of some cell line models of SDHB impairment, which show reduced growth compared to wild type. We hypothesize that reduced growth of SDHB-impaired monolayer culture models might reflect lack of support from sources within the tumor microenvironment. The present study therefore investigates how the microenvironment, modeled here by fibroblast co-culture, modulates cell metabolism, growth and invasion in an Sdhb-impaired mouse pheochromocytoma cell line. We employed two different constructs of short hairpin RNA to knockdown Sdhb and compared growth in a monolayer with and without fibroblast co-culture. Sdhb-silenced cells showed functional impairment of SDH with elevated succinate to fumarate ratio and decreased oxidative capacity. Cell growth was delayed with an increase in doubling time of 2&nbsp;h or 20&nbsp;h. Clonogenic cell survival and viability, on the other hand, were either unchanged or increased compared to control. In standard monolayer culture, no differences in pro-metastatic features were present. Co-culture with primary mouse fibroblast reversed the difference of proliferation between control and Sdhb knockdown but was unable to significantly influence invasiveness under these culture conditions. Metabolic studies identified that lactate secreted by fibroblasts was taken up preferentially by Sdhb-silenced cells. In summary, the present study identified a potential role for the tumor microenvironment in influencing phenotypic features of SDHB-mutated PGLs, providing a basis for the use of therapies targeted towards the tumor microenvironment

Evaluierung des mechanischen Komforts von Sitzpolstern in Radhosen - Eine initiale Datenanalyse

Um den Einfluss des Sitzpolsters in Radhosen auf den mechanischen Komfort besser zu verstehen, wurden der Satteldruck und die Beckenbewegung in Abhängigkeit der Belastungsintensität sowie -dauer beim Radfahren analysiert. Die Ergebnisse der initialen Datenanalyse deuten darauf hin, dass weniger die Stabilitätsparameter, sondern eher die Druckwahrnehmung für die Beurteilung des mechanischen Komforts maßgeblich ist.In order to better understand the influence of the seat pad in cycling shorts on mechanical comfort, saddle pressure and pelvic movement were analyzed as a function of load intensity as well as duration during cycling. The results of the initial data analysis indicate that it is not so much the stability parameters but rather the pressure perception that is decisive for the assessment of mechanical comfort