Comparison of Boost-Based MPPT Topologies for Space Applications

Several boost-derived topologies are analyzed and compared for an aerospace application that uses a 100 V voltage bus. All these topologies have been designed and optimized considering the electrical requirements and the reduced number of space-qualified components. The comparison evaluates the power losses, mass, and dynamic response. Special attention has been paid to those topologies that may cancel the inherent right half plane zero (RHP) zero of the boost topology. Experimental results of the less common topologies are presented.

Por la patria : colección de artículos (Manila 1895-1897) /

Mode of access: Internet.

YouTube - en främjare av demokrati eller demokratism? : En fallstudie i svenska riksdagspartiers politiska kommunikation på YouTube

Bakgrunden till studien är att Sverigedemokraterna kom in i riksdagen vid valet 2014. De sägs även vara mest aktiva på sociala medier av partierna, samtidigt som användningen av dessa medier som kanalen YouTube är vanligt för alla partier att sprida sin politiska kommunikation. Vårt syfte består av flera delar: dels att undersöka riksdagspartiernas YouTube-användning; dels att analysera text, diskursiv- och social praktik i politiska kommunikation hos partier med öppna kommentarfält. För att studera detta använder vi begreppen  “det goda samhället” och demokratism med avsikten att förstå och problematisera politisk kommunikationen på YouTube utifrån ett demokratiskt perspektiv. Teoretisk ram är Arthos (etisk propagandaanvändning), Calderaro (web 2.0s demokratifrämjande), Dahlgren (“det goda samhället” och demokratism), Ekman (extremhögergruppers YouTube-användning), Falkheimer & Heide (historisk överblick av strategisk kommunikaiton), Giansante (demokrati i social medier), Halpern & Gibbs (politiska diskussioner i kommentarfält) och Neumayer (politiskt oliktänkandes diskussion i kommentarfält). Materialet är alla åtta riksdagspartiers (Vänsterpartiet, Socialdemokraterna, Miljöpartiet, Centerpartiet, Kristdemokraterna, Liberalerna, Nya Moderaterna och Sverigedemokraterna) YouTube-kanaler med  kommentarfält och tre filmer och deras kommentarfält. Filmerna är en valfilm från 2014 från både Centern respektive Vänstern samt en reklamfilm från 2015 från SD. Metoden för analysen av YouTube-kanalerna och kommentarerna är en liten översiktlig kvantitativ deskriptiv innehållsanalys, medan den djupgående analysen av filmer och kommentarfält är Faircloughs kvalitativa kritiska diskursanalys kompletterad med semiotisk analys. Resultatet visar att äldre och stora har sedan 2014 många stängda fält och lägre videouppladdningsfrekvens, medan yngre och mindre partier generellt sedan 2014 har många öppna fält och hög videouppladdningsfrekvens. Av de tre undersökta partiernas filmer och fält tillåter minst två av dem kritisk dialog mellan politiskt oliktänkande i dessa vilket främjar demokratin. Slutsatsen är då att YouTube bidrar till utvecklingen av politisk kommunikation mot det demokratiskt goda samhället.

Cytochrome P450-mediated metabolism of haloperidol and reduced haloperidol to pyridinium metabolites

Haloperidol ( HP) has been reported to undergo cytochrome P450 (P450)-mediated metabolism to potentially neurotoxic pyridinium metabolites; however, the chemical pathways and specific enzymes involved in these reactions remain to be identified. The aims of the current study were to (i) fully identify the cytochrome P450 enzymes capable of metabolizing HP to the pyridinium metabolite, 4-(4-chlorophenyl)- 1-(4-fluorophenyl)-4-oxobutylpyridinium (HPP+), and reduced HP (RHP) to 4-(4-chlorophenyl)- 1-(4-fluorophenyl)-4-hydroxybutylpyridinium (RHPP+); and (ii) determine whether 4-(4-chlorophenyl)- 1-(4-fluorophenyl)-4-oxobutyl-1,2,3,6-tetrahydropyridine (HPTP) and 4-(4-chlorophenyl)1-( 4-fluorophenyl)-4-hydroxybutyl-1,2,3,6-tetrahydropyridine (RHPTP) were metabolic intermediates in these pathways. In vitro studies were conducted using human liver microsomal preparations and recombinant human cytochrome P450 enzymes (P450s 1A1, 1A2, 1B1, 2A6, 2B6, 2C9, 2C19 2D6, 2E1, 3A4, 3A5, and 3A7) expressed in bicistronic format with human NADPH cytochrome P450 reductase in Escherichia coli membranes. Pyridinium formation from HP and RHP was highly correlated across liver preparations, suggesting the same enzyme or enzymes were responsible for both reactions. Cytochrome P450s 3A4, 3A5, and 3A7 were the only recombinant enzymes which demonstrated significant catalytic activity under optimized conditions, although trace levels of activity could be catalyzed by NADPHP450 reductase alone. NADPH-P450 reductase-mediated activity was inhibited by reduced glutathione but not catalase or superoxide dismutase, suggesting O-2-dependent oxidation. No evidence was obtained to support the contention that HPTP and RHPTP are intermediates in these pathways. K-m values for HPP+ (34 +/- 5 mu M) and RHPP+ (64 +/- 4 mu M) formation by recombinant P450 3A4 agreed well with those obtained with human liver microsomes, consistent with P450 3A4 being the major catalyst of pyridinium metabolite formation in human liver.

Riemann-Hilbert Problems with Canonical Normalization and Families of Commuting Operators

2010 Mathematics Subject Classification: 35Q15, 31A25, 37K10, 35Q58.

Complex contests and the influence of aggressiveness in pigs

Animal contests vary greatly in behavioural tactics used and intensity reached, with some encounters resolved without physical contact while others escalate to damaging fighting. However, the reasons for such variation remains to be fully explained. Aggressiveness, in terms of a personality trait, offers a potentially important source of variation that has typically been overlooked. Therefore, we studied how aggressiveness as a personality trait influenced escalation between contestants matched for resource holding potential (RHP), using detailed observations of the contest behaviour, contest dynamics, and escalation levels. We predicted that winner and loser behaviour would differ depending on personality. This was tested by examining 52 dyadic contests between pigs (Sus scrofa). Aggressiveness was assayed in resident-intruder tests prior to the contest. Contests were then staged between pigs matched for RHP in terms of body weight but differing in their aggressiveness. In 27% of the contests a winner emerged without escalated physical fighting, demonstrating that a fight is not a prerequisite between RHP-matched contestants. However, the duration of contests with or without fighting was the same. In contests without a fight, opponents spent more time on mutual investigation and non-contact displays such as parallel walking, which suggests that ritualized display may facilitate assessment and decision making. Winners low in aggressiveness invested more time in opponent investigation and display and showed substantially less aggression towards the loser after its retreat compared to aggressive winners. Aggressiveness influenced contest dynamics but did not predict the level of escalation. Prominent behavioural differences were found for the interaction between personality and outcome and we therefore recommend including this interaction in models where personality is considered. Analyses based on contest duration only would miss many of the subtleties which are shown here and we therefore encourage more detailed analyses of animal contests, irrespective of the level of contest escalation.