At Physiological Temperatures the ATPase Rates of Shortening Soleus and Psoas Myofibrils Are Similar

AbstractWe obtained the temperature dependences of the adenosine triphosphatase (ATPase) activities (calcium-activated and relaxed) of myofibrils from a slow muscle, which we compared with those from a fast muscle. We chose rabbit soleus and psoas because their myosin heavy chains are almost pure: isoforms I and IIX, respectively. The Arrhenius plots of the ATPases are linear (4–35°C) with energies of activation for soleus myofibrils 155kJmol−1 (activated) and 78kJmol−1 (relaxed). With psoas myofibrils, the energies of activation were 71kJmol−1 (activated) and 60kJmol−1 (relaxed). When extrapolated to 42°C the ATPase rates of the two types of myofibril were identical: 50s−1 (activated) and 0.23s−1 (relaxed). Whereas with psoas myofibrils the Km for adenosine triphosphate (activated ATPase) is relatively insensitive to temperature, that for soleus myofibrils increased from 0.3μM at 4°C to 66.5μM at 35°C. Our results illustrate the importance of temperature when comparing the mechanochemical coupling in different types of muscle. We discuss the problem of how to reconcile the similarity of the myofibrillar ATPase rates at physiological temperatures with their different mechanical properties

Topiramate in the treatment of severe myoclonic epilepsy in infancy

AbstractThe aim of this study was to assess the effectiveness of topiramate (TPM) as an add-on regimen in reducing seizure rate in a population sample of patients diagnosed with severe myoclonic epilepsy in infancy (SME). Eighteen patients were evaluated. The mean observation time was 10.5 months (range, 6–18 months). Seizure frequency and type were recorded. Topiramate was administered as an add-on regimen at a starting dose of 1 mg kg−1and titrated to a maximum of 6–8 mg per kg per day. Different escalation rates were used, mainly weekly or fortnightly increments of dose. Three patients (16.6%) became seizure free, and 10 (55.6%) had a >50% reduction in seizure frequency: six of them (22.2%) achieved a reduction greater than 75%. Side-effects were observed in nine patients , eight with a weekly titration schedule and one with a fortnightly schedule. TPM is effective as adjunctive therapy for SME. Side-effects were mild and transient, generally related to rapid dosage titration

Self-similar chain conformations in polymer gels

We use molecular dynamics simulations to study the swelling of randomly end-cross-linked polymer networks in good solvent conditions. We find that the equilibrium degree of swelling saturates at Q_eq = N_e**(3/5) for mean strand lengths N_s exceeding the melt entanglement length N_e. The internal structure of the network strands in the swollen state is characterized by a new exponent nu=0.72. Our findings are in contradiction to de Gennes' c*-theorem, which predicts Q_eq proportional N_s**(4/5) and nu=0.588. We present a simple Flory argument for a self-similar structure of mutually interpenetrating network strands, which yields nu=7/10 and otherwise recovers the classical Flory-Rehner theory. In particular, Q_eq = N_e**(3/5), if N_e is used as effective strand length.Comment: 4 pages, RevTex, 3 Figure

''Remembering'' World War II and willingness to fight : sociocultural factors in the social representation of historical warfare across 22 societies

Students from 22 nations answered a survey on the most important events in world history. At the national level, free recalling and a positive evaluation of World War II (WWII) were associated with World Values Survey willingness to fight for the country in a war and being a victorious nation. Willingness to fight, a more benign evaluation of WWII, and recall of WWII were associ- ated with nation-level scores on power distance and low postmaterialism, suggesting that values stressing obedience and competition between nations are associated with support for collective violence, whereas values of expressive individualism are negatively related. Internal political vio- lence was unrelated to willingness to fight, excluding direct learning as an explanation of legit- imization of violence. Recall of wars in general (operationalized by WWI recall) was also unrelated to willingness to fight. Results replicate and extend Archer and Gartner’s classic study showing the legitimization of violence by war to the domain of collective remembering

Topological Defects and Interactions in Nematic Emulsions

Inverse nematic emulsions in which surfactant-coated water droplets are dispersed in a nematic host fluid have distinctive properties that set them apart from dispersions of two isotropic fluids or of nematic droplets in an isotropic fluid. We present a comprehensive theoretical study of the distortions produced in the nematic host by the dispersed droplets and of solvent mediated dipolar interactions between droplets that lead to their experimentally observed chaining. A single droplet in a nematic host acts like a macroscopic hedgehog defect. Global boundary conditions force the nucleation of compensating topological defects in the nematic host. Using variational techniques, we show that in the lowest energy configuration, a single water droplet draws a single hedgehog out of the nematic host to form a tightly bound dipole. Configurations in which the water droplet is encircled by a disclination ring have higher energy. The droplet-dipole induces distortions in the nematic host that lead to an effective dipole-dipole interaction between droplets and hence to chaining.Comment: 17 double column pages prepared by RevTex, 15 eps figures included in text, 2 gif figures for Fig. 1

Social representations of history, wars and politics in Latin America, Europe and Africa

This study analyzes how people perceive world history on three continents: Latin America, Europe and Africa. A total of 1179 university students form Argentina, Brazil, Peru, Portugal, Spain, Guinea-Bissau, and Cape Verde were asked to evaluate world events and leaders in terms of their valence and importance. The results demonstrated that social representations of history show a Euro/North American-centric, long-term positive evaluation, recency, and socio- centric bias. Euro/North American-centric events and leaders were found to be rated as more important and were more positively perceived in general. Distant political events, like French or American Revolution, were considered to be more positive than XX century similar events, which supports the long-term positive evaluation bias hypothesis. The hypothesis on recency bias was partially substantiated. Confirming the existence of such bias, World War II was rated as more important than the previous XX century wars and revolutions. Socio-centric bias also received partial support. African participants rated Mandela as a more important leader than other participants did. Latin Americans rated Che Guevara less positively, which suggests that some leaders are generally idealized icons, not based on group belongingness. However, results did not bring support to the centrality of war hypothesis. Wars were indeed negatively evaluated and World War II was rated as an important and negative event. Nevertheless, war- and politics-related events were not perceived as more important than the Industrial Revolution, suggesting that people appraise the importance of long-term socioeconomic factors of history when responding to close-ended quantitative measures (vs. open-ended salience measures). Results are discussed in the framework of social representations of history.El estudio analiza como las personas perciben la historia mundial en tres continentes: Latinoamérica, Europa y África. 1179 estudiantes universitarios de Argentina, Brasil, Perú, Portugal, España, Guinea-Bissau y Cabo Verde evaluaron una lista de eventos mundiales y líderes en lo que concierne a su valoración e importancia. Los resultados han mostrado que la representación social de la historia se caracteriza por un Euro centrismo, una evaluación positiva a largo plazo, y por sesgos socio-céntricos. Los eventos “Occidentales” (vinculados a Europa y Norteamérica) fueron evaluados como más importantes y percibidos más positivamente que los no-Occidentales. Eventos políticos distantes, como la Revolución Francesa o Americana, fueron evaluados más positivamente que eventos similares del siglo XX, apoyando la hipótesis de la evaluación positiva del pasado lejano. La hipótesis del sesgo de recencia o proximidad fue parcialmente confirmada, ya que la II Guerra Mundial fue evaluada como más importante que revoluciones o guerras anteriores al siglo XX. El sesgo socio-céntrico también recibe apoyo parcial. Los africanos consideraron a Mandela como un líder más importante comparado con los otros participantes. Los Latinos americanos evaluaron Che Guevara menos positivamente, lo que sugiere que ciertos líderes son generalmente íconos idealizados, y su valoración positiva no se basa en la proximidad o la pertenencia grupal. Sin embargo, los resultados no apoyaron la hipótesis de la centralidad de la guerra. Las guerras fueron efectivamente evaluadas negativamente y la II Guerra Mundial fue evaluado como la guerra más importante y como un evento muy negativo. No obstante, las guerras y eventos políticos relacionados con la violencia no fueron percibidos como más importantes que la Revolución industrial, sugiriendo que las personas valoran la importancia general de los factores históricos socioeconómicos cuando responden a medidas cuantitativas cerradas (vs. medidas abiertas). Los resultados se analizan desde el marco teórico de las representaciones sociales de la Historia

Tuning bilayer twist using chiral counterions

From seashells to DNA, chirality is expressed at every level of biological structures. In self-assembled structures it may emerge cooperatively from chirality at the molecular scale. Amphiphilic molecules, for example, can form a variety of aggregates and mesophases that express the chirality of their constituent molecules at a supramolecular scale of micrometres (refs 1-3), Quantitative prediction of the large-scale chirality based on that at the molecular scale remains a largely unsolved problem. Furthermore, experimental control over the expression of chirality at the supramolecular level is difficult to achieve(4-7): mixing of different enantiomers usually results in phase separation(18). Here we present an experimental and theoretical description of a system in which chirality can be varied continuously and controllably ('tuned') in micrometre-scale structures. we observe the formation of twisted ribbons consisting of bilayers of gemini surfactants (two surfactant molecules covalently linked at their charged head groups). We find that the degree of twist and the pitch of the ribbons can be tuned by the introduction of opposite-handed chiral counterions in various proportions. This degree of control might be of practical value; for example, in the use of the helical structures as templates for helical crystallization of macromolecules(8,9).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62619/1/399566a0.pd

An Assessment of the UK’s Trade with Developing Countries under the Generalised System of Preferences

The European Union (EU) Generalised System of Preferences (GSP Scheme) grants preferential treatment to 88 eligible countries. There are, however, concerns that the restrictive features (such as Rules of Origin, Low Preference Margin and Low Coverage) of the existing scheme indicate gravitation towards commercial trade agenda to which efficiency imperatives appear subordinated. Whether these concerns are genuine is an empirical question whose answer largely determines whether, after Brexit, the UK continues with the existing specifics of the EU scheme or develops a more inclusive UK-specific GSP framework. This study quantitatively examines the efficiency of the EU GSP as it relates to UK beneficiaries from 2014 to 2017. We draw on the descriptive efficiency estimation (The utilisation Rate, Potential Coverage Rate, and the Utility Rate) using import data across 88 beneficiary countries and agricultural products of the Harmonised System Code Chapter 1 to 24. Asides the Rules of Origin that, generally, harm the uptake of GSP, low preference margin is found to cause low utilisation rates in a non-linear manner. Essentially, a more robust option (such that allows “global Cumulation” or broader product coverage) could, substantially, lower the existing barriers to trade and upsurge the efficiency of the GSP scheme