Resolving the Crab pulsar wind nebula at teraelectronvolt energies

The Crab nebula is one of the most-studied cosmic particle accelerators, shining brightly across the entire electromagnetic spectrum up to very-high-energy gamma rays1,2. It is known from observations in the radio to gamma-ray part of the spectrum that the nebula is powered by a pulsar, which converts most of its rotational energy losses into a highly relativistic outflow. This outflow powers a pulsar wind nebula, a region of up to ten light-years across, filled with relativistic electrons and positrons. These particles emit synchrotron photons in the ambient magnetic field and produce very-high-energy gamma rays by Compton up-scattering of ambient low-energy photons. Although the synchrotron morphology of the nebula is well established, it has not been known from which region the very-high-energy gamma rays are emitted3,4,5,6,7,8. Here we report that the Crab nebula has an angular extension at gamma-ray energies of 52 arcseconds (assuming a Gaussian source width), much larger than at X-ray energies. This result closes a gap in the multi-wavelength coverage of the nebula, revealing the emission region of the highest-energy gamma rays. These gamma rays enable us to probe a previously inaccessible electron and positron energy range. We find that simulations of the electromagnetic emission reproduce our measurement, pro

Guidelines to design tangible tabletop activities for children with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder is one of the most frequent neurodevelopmental disorders among children. In spite of this, there is a lack of HCI research specifically devoted to these children. This paper describes efforts to transfer previous experience with other neurodiverse children in the field of tangible tabletops to ADHD children. The results of evaluation sessions carried out in conjunction with an ADHD association, complemented with an in-depth study of their special characteristics and needs, have led to a set of guidelines oriented to the design of tangible tabletop activities. These guidelines are mostly general and applicable to the design of any interactive application oriented to ADHD children. They are also appropriate for applications for other neurodiverse children or, in fact, any child from a more inclusive perspective

INTERACTIVE POLYPHENOLS-BASED BIOPACKAGING FOR FOOD PRESERVATION: AN IN VITRO STUDY

Producing green, sustainable and renewable materials is one of the major challenge nowadays in the food-packaging sector. In this context, the aim of our study is to develop an active cellulose-based packaging, cellulose in fact is one of the most plentiful polymer on the earth. Tetrahydrocurcumin (THC), a derivative of curcuma, chosen as antioxidant and antimicrobial natural substance, was added into a cellulose matrix (1.5% w/w) and the resulting material was then studied. In addition to this active compound, the paper also contained chitosan and carboxymethylcellulose, to improve the retention of THC and the mechanical properties. Mechanical, chemical and microbiological analyses were done to completely characterize the active papers. Grammage, dry and wet strength were determined. The polyphenol content was determined by the Folin-Ciolcalteu method. Antimicrobial activity of THC, in solution and after its incorporation into the papers, was tested against Gram negative bacteria (Escherichia coli and Pseudomonas putida), Gram positive bacteria (Staphylococcus aureus and Listeria innocua) and moulds (Penicillium chrysogenum and Aspergillus niger). Antioxidant capacity was also tested through the DPPH method. THC solution presented a good antioxidant capacity: it showed an EC50 equal to 4,49 ppm ( EC50 of Trolox was 2,86 ppm). Its minimal inhibitory concentration is 0,4 g/L for Gram positive bacteria, and higher than 0,6 g/L for Gram negative. THC solution was found effective in delaying the development of moulds. THC polyphenols were quantified as 0,8% on paper weight for the paper containing THC and these quantities together with chitosan resulted able to slow down the growth of microorganism. Pseudomonas is inhibited by the presence of chitosan and THC is able to amplify the antimicrobial activity of chitosan, by inhibiting also the growth of Staphylococcus and E. Coli. The presence of THC does neither affect the mechanical properties of papers, nor the color and the odor. Based on these results, it is possible to conclude that THC exhibits good antioxidant and moderate antimicrobial properties. Paper sheets didn’t lose their mechanical properties. These data will pave the way to the use of THC for the production of an active paper-based packaging to improve the shelf life of food items

About a class of Hadamard propelinear codes

This article aims to explore the algebraic structure of Hadamard propelinear codes, which are not abelian in general but they have good algebraic and combinatorial properties. We construct a subclass of Hadamard propelinear codes which enlarges the family of the Hadamard translation invariant propelinear codes. Several papers have been devoted to the relations between difference sets, t-designs, cocyclic-matrices and Hadamard groups, and we present a link between them and a class of Hadamard propelinear codes, which we call full propelinear. Finally, as an exemplification, we provide a full propelinear structure for all Hadamard codes of length sixteen

Kronecker sums to construct Hadamard full propelinear codes of type CnQ₈

Publicació amb motiu de la 21st Conference on Applications of Computer Algebra (July 20-24, 2015, Kalamata, Greece

Production of carboxylates from high rate activated sludge through fermentation

The aim of this work was to study the key parameters affecting fermentation of high rate activated A-sludge to carboxylates, including pH, temperature, inoculum, sludge composition and iron content. The maximum volatile fatty acids production was 141 mg C g1 VSSfed, at pH 7. Subsequently the potentialfor carboxylate and methane production for A-sludge from four different plants at pH 7 and 35 C were compared. Initial BOD of the sludge appeared to be key determining carboxylate yield from A-sludge. Whereas methanogenesis could be correlated linearly to the quantity of ferric used for coagulation, fermentation did not show a dependency on iron presence. This difference may enable a strategywhereby A-stage sludge is separated to achieve fermentation, and iron dosing for phosphate removal is only implemented at the B-stage

Insuficiencia cardíaca. Tratamiento farmacológico actual

Treatment of heart failure (HF) has changed in recent years, despite the paucity of new approved drugs. Current treatment is directed not only towards improving symptoms, but also to preventing the development from asymptomatic systolic dysfunction to symptomatic heart failure, to preventing cardiac remodelling, renal dysfunction and to reducing mortality. The main families of drugs currently used are: cardiac glycosides, diuretics, angiotensin-converting enzyme inhibitors (ACEI), beta-blocking drugs (BB), angiotensin-II receptor blockers (ARB) and aldosterone receptor antagonists. The combination isosorbide dinitrate + hydralazine is hardly used due to its side effects and none of the new positive inotropic drugs has been approved in chronic HF, because all of them increase mortality. Levosimendan is a new positive inotropic agent approved for acute HF by an intravenous route, with a favourable effect on prognosis vs placebo and vs dobutamine (which worsens the prognosis). The approved oral drugs can be given at the same time if the patient tolerates them, because their beneficial effect is additive. Mortality in two years in mild to moderate HF is 34% with glycosides + diuretics. It falls to 22% when an ACEI is added, to 14% when a BB is added and to 10% when an aldosterone antagonist is added. ARB can be given instead of an ACEI or be added to the other drugs

Environmental constraints influencing survival of an African parasite in a north temperate habitat: effects of temperature on egg development

SUMMARYFactors affecting survival of parasites introduced to new geographical regions include changes in environmental temperature. Protopolystoma xenopodis is a monogenean introduced with the amphibian Xenopus laevis from South Africa to Wales (probably in the 1960s) where low water temperatures impose major constraints on life-cycle processes. Effects were quantified by maintenance of eggs from infections in Wales under controlled conditions at 10, 12, 15, 18, 20 and 25°C. The threshold for egg viability/ development was 15°C. Mean times to hatching were 22 days at 25°C, 32 days at 20°C, extending to 66 days at 15°C. Field temperature records provided calibration of transmission schedules. Although egg production continues year-round, all eggs produced during >8 months/ year die without hatching. Output contributing significantly to transmission is restricted to 10 weeks (May-mid-July). Host infection, beginning after a time lag of 8 weeks for egg development, is also restricted to 10 weeks (July-September). Habitat temperatures (mean 15·5°C in summer 2008) allow only a narrow margin for life-cycle progress: even small temperature increases, predicted with 'global warming', enhance infection. This system provides empirical data on the metrics of transmission permitting long-term persistence of isolated parasite populations in limiting environments

Will all scientists working on snails and the diseases they transmit please stand up?

Copyright © 2012 Adema et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.No abstract available