Conductor losses calculation in two-dimensional simulations of H-plane rectangular waveguides

This paper presents a novel numerical approach to simulate H-plane rectangular-waveguide microwave circuits considering a reduced quasi-2D simulation domain with benefits for computational cost and time. With the aim to evaluate the attenuation of the full height 3D component, we propose a modified expression for the waveguide top/bottom wall conductivity. Numerical 2D simulations are validated against results from full wave 3-D commercial electromagnetic simulator. After a benchmark on a simple straight waveguide model, the method has been successfully applied to an asymmetric un-balanced power splitter, where an accurate power loss prediction is mandatory. Simulation time and memory consumption can be reduced by a factor ten and seven respectively, in comparison with complete 3D geometries. Finally, we show that, also for quasi-2D E-bend waveguide, a case where the translational H-plane symmetry is broken, the error on conductor losses computation is mitigated by our approach since the method remains still valid in a first approximation

Implicancias jurídico-institucionales de la puesta en disposición de las obras de autor en entornos digitales

El presente trabajo tiene por objetivo realizar un análisis de la gestión universitaria que desarrolla el área de la Biblioteca Digital de la Universidad Nacional de Cuyo, en particular a partir de la problemática de la puesta en disposición de las obras de los docentes investigadores de la comunidad universitaria, en entornos digitales de libre acceso. En el marco de esta temática se deben tener en cuenta grandes desafíos de la gestión universitaria que involucran el acceso y la protección de las obras intelectuales en un mismo sistema. Siendo este último el ámbito de interacción de las tensiones del modelo productivo de la reconocida “Sociedad de la Información

Reviw: Business associations as a defensive response to post-communist predatory states

Book review Building Business in Post-Communist Russia, Eastern Europe, and Eurasia: Collective Goods, Selective Incentives, and Predatory States, by Dinissa Duvanova, 2013, New York: Cambridge University Press

A Scientific Approach to Understanding the Head Trauma Endured by a Mixed Martial Arts Fighter

The purpose of this research is to gain some insight on the type of head trauma an athlete may encounter during mixed martial arts (MMA) competition. These athletes endure continuous blows to the head throughout their training and fighting career. The knowledge obtained from this research may assist MMA athletes and trainers in assessing the way they train, how they compete and, more importantly, how long they choose to compete in their amateur or professional MMA career. The analysis is performed by first creating a three-dimensional solid model of the human head based on geometric coordinates originally obtained from a cadaver. The geometry is then imported into a Finite Element Analysis (FEA) software and validated by simulating a benchmark model based on experimental results. This research utilizes experimental data provided by the National Geographic on impact loads of various MMA striking techniques applied to the already validated geometry and FEA model to obtain the resulting pressure that occurs in the brain of the human head. These results are subsequently analyzed to determine how severe this trauma may be to an athlete. Key points such as ways to further improve the FEA results are also discussed

About the screening of the charge of a proton migrating in a metal

The amount of screening of a proton in a metal, migrating under the influence of an applied electric field, is calculated using different theoretical formulations. First the lowest order screening expression derived by Sham (1975) is evaluated. In addition 'exact' expressions are evaluated which were derived according to different approaches. For a proton in a metal modeled as a jellium the screening appears to be 15 +/- 10 %, which is neither negligible not reconcilable with the controversial full-screening point of view of Bosvieux and Friedel (1962). In reconsidering the theory of electromigration, a new simplified linear-response expression for the driving force is shown to lead to essentially the same result as found by Sorbello (1985), who has used a rather complicated technique. The expressions allow for a reduction such that only the scattering phase shifts of the migrating impurity are required. Finally it is shown that the starting formula for the driving force of Bosvieux and Friedel leads exactly to the zero-temperature limit of well-established linear response descriptions, by which the sting of the controversy has been removed.Comment: 14 pages, 5 figure

Vizualizacija dišnog puta: oči vide ono što mozak zna

Airway management is basic for anesthesia practice, and sometimes it can represent a really dramatic scenario for both the patient and the physicians. Laryngoscopy has been the gold standard of airway visualization for more than 60 years, showing its limitations and failure rates with time. New technology has made available an opportunity to move the physician’s eye inside patient airways thanks to video laryngoscopy and video assisted airway management technique. Undoubtedly, we have entered a new era of high resolution airway visualization and different approach in airway instrumentation. Nevertheless, each new technology needs time to be tested and considered reliable, and pitfalls and limitations may come out with careful and long lasting analysis, so it is probably not the right time yet to promote video assisted approach as a new gold standard for airway visualization, despite the fact that it certainly offers some new prospects. In any case, whatever the visualization approach, no patient dies because of missed airway visualization or failed intubation, but due to failed ventilation, which remains without doubt the gold standard of any patient safety goal and airway management technique.Održavanje dišnog puta je osnovna anesteziološka vještina koja ponekad predstavlja u pravom smislu dramatičan scenarij za bolesnika i liječnika. Laringoskopija, sa svim svojim ograničenjima i neuspjesima, predstavlja zlatni standard vizualizacije dišnog puta već više od 60 godina. Nove tehnologije, zahvaljujući videolaringoskopiji i video asistiranim tehnikamaodržavanja dišnog puta, omogućile su pomicanje očiju liječnika unutar dišnog puta bolesnika. Bez sumnje, ušli smo u novu eru visoke rezolucije vizualizacije dišnog puta i različitog pristupa instrumentalizaciji dišnog puta. Međutim, svaka nova tehnologija zahtijeva vrijeme da bi se testirala i smatrala pouzdanom. Zapreke i ograničenja mogu se iznjedriti nakon pažljive i dugotrajne analize, stoga vjerojatno još nije vrijeme da se promovira video asistirani pristup kao novi zlatni standard u vizualizaciji dišnog puta, iako on definitivno predstavlja novu budućnost. U svakom slučaju, koji kod bio pristup vizualizaciji, nijedan bolesnik ne umire zbog propuštene vizualizacije ili neuspjele intubacije, već umire zbog neuspješne ventilacije koja ostaje bez sumnje zlatni standard bilo kojeg cilja za sigurnost bolesnika i tehnike zbrinjavanja dišnog puta

Fiberoptička bronhoskopija prema video laringoskopiji u zbrinjavanju pedijatrijskog dišnog puta

The primary goal of pediatric airway management is to ensure oxygenation and ventilation. Routine airway management in healthy pediatric patients is normally easy in experienced hands. Really difficult pediatric airway is rare and usually is associated with anatomically and physiologically important findings such as congenital abnormalities and syndromes, trauma, infection, swelling and burns. Using predictors of difficult intubation should be mandatory preoperative assessment in pediatric patients. Difficult airway algorithm for pediatric patients has to consist of three parts: oxygenation (A), tracheal intubation (B), and rescue (C). According to this new algorithm, if conventional direct laryngoscopy fails, we have to use alternative glottic visualization device. Do we really need video laryngoscopy? If we look at numbers, we might estimate that conventional laryngoscopy is successful and effective in around 98.5% of cases. Do we need to replace Macintosh laryngoscope with video laryngoscope completely in our routine practice? Should video laryngoscope be available to replace fiberoptic intubation in pediatric airway management? According to the algorithm, fiberoptic-assisted tracheal intubation combined with extraglottic airway devices is the standard of care. Establishment of protocols for equipping and maintaining airway trolleys and regular training in their use must be provided to avoid tissue hypoxia in children with compromised airway.Primarni cilj u upravljanju pedijatrijskim dišnim putem je osigurati oksigenaciju i ventilaciju. Upravljanje dišnim putem kod pedijatrijskih bolesnika je rutina u rukama iskusnog pedijatrijskog anesteziologa. Problematičan dišni put kod pedijatrijskih bolesnika je rijetkost i vezan je za anatomske i fiziološke nalaze kao što su kongenitalne anomalije i sindromi, traume, infekcije, oticanje i opekline. U prijeoperacijskoj pripremi pedijatrijskih bolesnika obvezno je korištenje prediktora za procjenu dišnog puta. Algoritam za teški dišni put kod pedijatrijskih bolesnika sastoji se od tri dijela: oksigenacije (A), intubacije (B) i spašavanja (C). Prema ovom algoritmu, ako se konvencionalnom laringoskopijom ne uspije vizualizirati glotis i realizirati intubacija, potrebno je koristiti alternativne alatke za vizualizaciju glotisa i intubaciju bolesnika. Ako se pogleda statistika, konvencionalna laringoskopija je uspješna i učinkovita u oko 98,5% slučajeva. Trebamo li zamijeniti Macintosh laringoskop video laringoskopom u našem svakodnevnom radu s pedijatrijskim bolesnicima? Je li video laringoskopska (indirektna) intubacija dostojna zamjena za fiberoptičku intubaciju kada je pedijatrijski dišni put u pitanju? Prema algoritmu fiberoptička intubacija u kombinaciji sa supraglotičnim alatkama za zbrinjavanje pedijatrijskog dišnog puta je standard. Uspostava protokola za opremanje, upravljanje i održavanje dišnih putova kod pedijatrijskih bolesnika te redovita obuka u uporabi alatki za zbrinjavanje dišnog puta je neophodna